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• Convergent synthetic approaches to polycyclic aromatic dicarboximides. Shoyama, Kazutaka; Würthner, Frank. In Org. Chem. Front., 12(1), pp. 328–345. 2025.
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  Polycyclic aromatic dicarboximides (PADIs) as represented by naphthalene and perylene bis(dicarboximides) are useful molecules for a variety of functional materials and remain important synthetic targets for organic chemists. In this review, we summarize recent developments in the convergent synthetic approaches using palladium-catalysed annulation of peri-activated naphthalimides. Contrary to conventional linear synthetic methods where a single starting material is converted into a target molecule through a stepwise manner, the herein discussed convergent synthetic method enables rapid extension of the π-scaffold by combining multiple polyaromatic substrates into one. This method opened new possibilities for π-extended dicarboximides with so far up to five imide groups. Further exploration of annulation strategies may allow the preparation of previously inaccessible PADIs with fascinating molecular and material properties.

  @article{D4QO01828A, abstract = {Polycyclic aromatic dicarboximides (PADIs) as represented by naphthalene and perylene bis(dicarboximides) are useful molecules for a variety of functional materials and remain important synthetic targets for organic chemists. In this review{,} we summarize recent developments in the convergent synthetic approaches using palladium-catalysed annulation of peri-activated naphthalimides. Contrary to conventional linear synthetic methods where a single starting material is converted into a target molecule through a stepwise manner{,} the herein discussed convergent synthetic method enables rapid extension of the π-scaffold by combining multiple polyaromatic substrates into one. This method opened new possibilities for π-extended dicarboximides with so far up to five imide groups. Further exploration of annulation strategies may allow the preparation of previously inaccessible PADIs with fascinating molecular and material properties.}, author = {Shoyama, Kazutaka and Würthner, Frank}, journal = {Org. Chem. Front.}, keywords = {myown}, number = 1, pages = {328-345}, publisher = {The Royal Society of Chemistry}, title = {Convergent synthetic approaches to polycyclic aromatic dicarboximides}, volume = 12, year = 2025 }

  %0 Journal Article %1 D4QO01828A %A Shoyama, Kazutaka %A Würthner, Frank %D 2025 %I The Royal Society of Chemistry %J Org. Chem. Front. %N 1 %P 328-345 %R 10.1039/D4QO01828A %T Convergent synthetic approaches to polycyclic aromatic dicarboximides %U http://dx.doi.org/10.1039/D4QO01828A %V 12 %X Polycyclic aromatic dicarboximides (PADIs) as represented by naphthalene and perylene bis(dicarboximides) are useful molecules for a variety of functional materials and remain important synthetic targets for organic chemists. In this review, we summarize recent developments in the convergent synthetic approaches using palladium-catalysed annulation of peri-activated naphthalimides. Contrary to conventional linear synthetic methods where a single starting material is converted into a target molecule through a stepwise manner, the herein discussed convergent synthetic method enables rapid extension of the π-scaffold by combining multiple polyaromatic substrates into one. This method opened new possibilities for π-extended dicarboximides with so far up to five imide groups. Further exploration of annulation strategies may allow the preparation of previously inaccessible PADIs with fascinating molecular and material properties.

• Ternary π–π Stacking Complexes by Allosteric Regulation in Multilayer Nanographenes. Niyas, M. A.; Shoyama, Kazutaka; Würthner, Frank. In J. Am. Chem. Soc., 146(43), pp. 29728–29734. 2024.
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  Construction of π–π stacking supramolecular complexes with more than two different components is challenging due to the weak and directionless nature of dispersion interactions. Here, we report ternary complexes of a ditopic nanographene tetraimide (1), α-substituted phthalocyanine (Pc), and polyaromatic hydrocarbons (PAHs) in solution and the crystalline state via allosteric regulation. Binding of one Pc gives rise to significant distortion and conformational changes in 1 that in turn lead to the inhibition of the second binding of Pc. The conformational changes associated with first binding allowed an allosteric binding of a third component (PAHs) to form ternary complexes in solution. 1H NMR titration revealed moderately high thermodynamic stability for the ternary complexes in CDCl3. Competition between allosterically regulated ternary complexes ([Pc·1·PAH]) and 1:2 stoichiometric binary complexes of 1 with PAHs ([PAH·1·PAH]) was elucidated. Further, the selective formation of ternary complexes in solution led to the generation of ternary cocrystals from a 1:1:1 mixture of three components in solution. Our work shows that large π-conjugated nanographenes designed with allosteric recognition sites allow the construction of multilayer ternary complexes in solution and the solid state even with dispersive π–π interactions.

  @article{Niyas_2024, abstract = {Construction of π–π stacking supramolecular complexes with more than two different components is challenging due to the weak and directionless nature of dispersion interactions. Here, we report ternary complexes of a ditopic nanographene tetraimide (1), α-substituted phthalocyanine (Pc), and polyaromatic hydrocarbons (PAHs) in solution and the crystalline state via allosteric regulation. Binding of one Pc gives rise to significant distortion and conformational changes in 1 that in turn lead to the inhibition of the second binding of Pc. The conformational changes associated with first binding allowed an allosteric binding of a third component (PAHs) to form ternary complexes in solution. 1H NMR titration revealed moderately high thermodynamic stability for the ternary complexes in CDCl3. Competition between allosterically regulated ternary complexes ([Pc·1·PAH]) and 1:2 stoichiometric binary complexes of 1 with PAHs ([PAH·1·PAH]) was elucidated. Further, the selective formation of ternary complexes in solution led to the generation of ternary cocrystals from a 1:1:1 mixture of three components in solution. Our work shows that large π-conjugated nanographenes designed with allosteric recognition sites allow the construction of multilayer ternary complexes in solution and the solid state even with dispersive π–π interactions.}, author = {Niyas, M. A. and Shoyama, Kazutaka and Würthner, Frank}, journal = {J. Am. Chem. Soc.}, keywords = {myown}, month = 10, number = 43, pages = {29728–29734}, publisher = {American Chemical Society (ACS)}, title = {Ternary π–π Stacking Complexes by Allosteric Regulation in Multilayer Nanographenes}, volume = 146, year = 2024 }

  %0 Journal Article %1 Niyas_2024 %A Niyas, M. A. %A Shoyama, Kazutaka %A Würthner, Frank %D 2024 %I American Chemical Society (ACS) %J J. Am. Chem. Soc. %N 43 %P 29728–29734 %R 10.1021/jacs.4c11119 %T Ternary π–π Stacking Complexes by Allosteric Regulation in Multilayer Nanographenes %U http://dx.doi.org/10.1021/jacs.4c11119 %V 146 %X Construction of π–π stacking supramolecular complexes with more than two different components is challenging due to the weak and directionless nature of dispersion interactions. Here, we report ternary complexes of a ditopic nanographene tetraimide (1), α-substituted phthalocyanine (Pc), and polyaromatic hydrocarbons (PAHs) in solution and the crystalline state via allosteric regulation. Binding of one Pc gives rise to significant distortion and conformational changes in 1 that in turn lead to the inhibition of the second binding of Pc. The conformational changes associated with first binding allowed an allosteric binding of a third component (PAHs) to form ternary complexes in solution. 1H NMR titration revealed moderately high thermodynamic stability for the ternary complexes in CDCl3. Competition between allosterically regulated ternary complexes ([Pc·1·PAH]) and 1:2 stoichiometric binary complexes of 1 with PAHs ([PAH·1·PAH]) was elucidated. Further, the selective formation of ternary complexes in solution led to the generation of ternary cocrystals from a 1:1:1 mixture of three components in solution. Our work shows that large π-conjugated nanographenes designed with allosteric recognition sites allow the construction of multilayer ternary complexes in solution and the solid state even with dispersive π–π interactions.
• A Monodisperse, End‐Capped Ru(bda) Oligomer with Outstanding Performance in Heterogeneous Electrochemical Water Oxidation. Schneider, Tilman; Seebauer, Florian; Beuerle, Florian; Würthner, Frank. In Adv. Mater. Technol., 9(11). 2024.
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  Water oxidation catalysis is a key step for sustainable fuel production by water splitting into hydrogen and oxygen. The synthesis of a novel coordination oligomer based on four Ru(bda) (bda = 2,2′-bipyridine-6,6′-dicarboxylate) centers, three 4,4′-bipyridine (4,4′-bpy) linkers, and two 4-picoline (4-pic) end caps is reported. The monodispersity of this tetranuclear compound is characterized by NMR techniques. Heterogeneous electrochemical water oxidation after immobilization on multi-walled carbon nanotubes (MWCNTs) shows catalytic performance unprecedented for this compound class, with a turnover frequency (TOF) of 133 s−1 and a turnover number (TON) of 4.89 × 106, at a current density of 43.8 mA cm−2 and a potential of 1.45 V versus normal hydrogen electrode (NHE).

  @article{Schneider_2024, abstract = {Water oxidation catalysis is a key step for sustainable fuel production by water splitting into hydrogen and oxygen. The synthesis of a novel coordination oligomer based on four Ru(bda) (bda = 2,2′-bipyridine-6,6′-dicarboxylate) centers, three 4,4′-bipyridine (4,4′-bpy) linkers, and two 4-picoline (4-pic) end caps is reported. The monodispersity of this tetranuclear compound is characterized by NMR techniques. Heterogeneous electrochemical water oxidation after immobilization on multi-walled carbon nanotubes (MWCNTs) shows catalytic performance unprecedented for this compound class, with a turnover frequency (TOF) of 133 s−1 and a turnover number (TON) of 4.89 × 106, at a current density of 43.8 mA cm−2 and a potential of 1.45 V versus normal hydrogen electrode (NHE).}, author = {Schneider, Tilman and Seebauer, Florian and Beuerle, Florian and Würthner, Frank}, journal = {Adv. Mater. Technol.}, keywords = {myown}, month = {01}, number = 11, publisher = {Wiley}, title = {A Monodisperse, End‐Capped Ru(bda) Oligomer with Outstanding Performance in Heterogeneous Electrochemical Water Oxidation}, volume = 9, year = 2024 }

  %0 Journal Article %1 Schneider_2024 %A Schneider, Tilman %A Seebauer, Florian %A Beuerle, Florian %A Würthner, Frank %D 2024 %I Wiley %J Adv. Mater. Technol. %N 11 %R 10.1002/admt.202301721 %T A Monodisperse, End‐Capped Ru(bda) Oligomer with Outstanding Performance in Heterogeneous Electrochemical Water Oxidation %U http://dx.doi.org/10.1002/admt.202301721 %V 9 %X Water oxidation catalysis is a key step for sustainable fuel production by water splitting into hydrogen and oxygen. The synthesis of a novel coordination oligomer based on four Ru(bda) (bda = 2,2′-bipyridine-6,6′-dicarboxylate) centers, three 4,4′-bipyridine (4,4′-bpy) linkers, and two 4-picoline (4-pic) end caps is reported. The monodispersity of this tetranuclear compound is characterized by NMR techniques. Heterogeneous electrochemical water oxidation after immobilization on multi-walled carbon nanotubes (MWCNTs) shows catalytic performance unprecedented for this compound class, with a turnover frequency (TOF) of 133 s−1 and a turnover number (TON) of 4.89 × 106, at a current density of 43.8 mA cm−2 and a potential of 1.45 V versus normal hydrogen electrode (NHE).
• Isothermal Phase Transitions in Liquid Crystals Driven by Dynamic Covalent Chemistry. Martínez, Daniel; Schlossarek, Tim; Würthner, Frank; Soberats, Bartolome. In Angew. Chem. Int. Ed., 63(26). 2024.
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  The dynamic nature of calamitic liquid crystals is exploited to perform isothermal phase transitions driven by dynamic covalent chemistry. For this purpose, nematic (N) arrays based on aldehyde 1 were treated with different amines (A–E) in an on-surface process, which resulted in different isothermal phase transitions. These phase transformations were caused by in situ imination reactions and are dependent on the nature of the added amine. Transitions from the N to crystal (1A, 1E), isotropic (1B), and smectic (Sm) (1C, 1D) phases were achieved, while the resulting materials feature thermotropic liquid crystal behavior. A sequential trans- formation from the N 1 to the Sm 1C and then to the N 1B was achieved by coupling an imination to a transimination processes and adjusting the temperature. All of these processes were well characterized by micro- scopic, spectroscopic, and X-ray techniques, unlocking not only the constitutional but also the structural aspects of the phase transitions. This work provides new insights into designing constitutionally and structurally adaptable liquid crystal systems, paving the way toward the conception of programable evolutive pathways and adaptive materials.

  @article{Mart_nez_2024, abstract = {The dynamic nature of calamitic liquid crystals is exploited to perform isothermal phase transitions driven by dynamic covalent chemistry. For this purpose, nematic (N) arrays based on aldehyde 1 were treated with different amines (A–E) in an on-surface process, which resulted in different isothermal phase transitions. These phase transformations were caused by in situ imination reactions and are dependent on the nature of the added amine. Transitions from the N to crystal (1A, 1E), isotropic (1B), and smectic (Sm) (1C, 1D) phases were achieved, while the resulting materials feature thermotropic liquid crystal behavior. A sequential trans- formation from the N 1 to the Sm 1C and then to the N 1B was achieved by coupling an imination to a transimination processes and adjusting the temperature. All of these processes were well characterized by micro- scopic, spectroscopic, and X-ray techniques, unlocking not only the constitutional but also the structural aspects of the phase transitions. This work provides new insights into designing constitutionally and structurally adaptable liquid crystal systems, paving the way toward the conception of programable evolutive pathways and adaptive materials.}, author = {Martínez, Daniel and Schlossarek, Tim and Würthner, Frank and Soberats, Bartolome}, journal = {Angew. Chem. Int. Ed.}, keywords = {myown}, month = {05}, number = 26, publisher = {Wiley}, title = {Isothermal Phase Transitions in Liquid Crystals Driven by Dynamic Covalent Chemistry}, volume = 63, year = 2024 }

  %0 Journal Article %1 Mart_nez_2024 %A Martínez, Daniel %A Schlossarek, Tim %A Würthner, Frank %A Soberats, Bartolome %D 2024 %I Wiley %J Angew. Chem. Int. Ed. %N 26 %R 10.1002/anie.202403910 %T Isothermal Phase Transitions in Liquid Crystals Driven by Dynamic Covalent Chemistry %U http://dx.doi.org/10.1002/anie.202403910 %V 63 %X The dynamic nature of calamitic liquid crystals is exploited to perform isothermal phase transitions driven by dynamic covalent chemistry. For this purpose, nematic (N) arrays based on aldehyde 1 were treated with different amines (A–E) in an on-surface process, which resulted in different isothermal phase transitions. These phase transformations were caused by in situ imination reactions and are dependent on the nature of the added amine. Transitions from the N to crystal (1A, 1E), isotropic (1B), and smectic (Sm) (1C, 1D) phases were achieved, while the resulting materials feature thermotropic liquid crystal behavior. A sequential trans- formation from the N 1 to the Sm 1C and then to the N 1B was achieved by coupling an imination to a transimination processes and adjusting the temperature. All of these processes were well characterized by micro- scopic, spectroscopic, and X-ray techniques, unlocking not only the constitutional but also the structural aspects of the phase transitions. This work provides new insights into designing constitutionally and structurally adaptable liquid crystal systems, paving the way toward the conception of programable evolutive pathways and adaptive materials.
• Panchromatic light-harvesting antenna by supramolecular exciton band engineering for heteromeric dye foldamer. Schulz, Alexander; Fröhlich, Rebecca; Jayachandran, Ajay; Schneider, Franziska; Stolte, Matthias; Brixner, Tobias; Würthner, Frank. In Chem, 10(9), pp. 2887–2900. 2024.
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  Natural photosystems accomplish panchromatic light absorption by different chromophores that are non-covalently embedded in protein matrices and mostly lack close dye-dye interactions. In this article, we introduce a light-harvesting (LH) system established by four different merocyanine dyes that are co-facially stacked by dipole-dipole interactions and a peptide-like backbone in a folded heteromer architecture to afford a panchromatic absorption band consisting of several strongly coupled exciton states. This exciton manifold allows for ultrafast and efficient energy transport in the artificial antenna. Furthermore, due to the tight stacking of the dyes in their folded state, non-radiative processes are slowed down, thereby increasing the lifetime of the excited state and the fluorescence quantum yield from <3% for the individual dyes up to 38% for the folda-heteromer. Together with the panchromatic absorption, this leads to a substantial improvement of the fluorescence brightness upon broadband excitation in comparison with its constituent chromophores.

  @article{Schulz_2024, abstract = {Natural photosystems accomplish panchromatic light absorption by different chromophores that are non-covalently embedded in protein matrices and mostly lack close dye-dye interactions. In this article, we introduce a light-harvesting (LH) system established by four different merocyanine dyes that are co-facially stacked by dipole-dipole interactions and a peptide-like backbone in a folded heteromer architecture to afford a panchromatic absorption band consisting of several strongly coupled exciton states. This exciton manifold allows for ultrafast and efficient energy transport in the artificial antenna. Furthermore, due to the tight stacking of the dyes in their folded state, non-radiative processes are slowed down, thereby increasing the lifetime of the excited state and the fluorescence quantum yield from <3% for the individual dyes up to 38% for the folda-heteromer. Together with the panchromatic absorption, this leads to a substantial improvement of the fluorescence brightness upon broadband excitation in comparison with its constituent chromophores.}, author = {Schulz, Alexander and Fröhlich, Rebecca and Jayachandran, Ajay and Schneider, Franziska and Stolte, Matthias and Brixner, Tobias and Würthner, Frank}, journal = {Chem}, keywords = {myown}, month = {06}, number = 9, pages = {2887-2900}, publisher = {Elsevier BV}, title = {Panchromatic light-harvesting antenna by supramolecular exciton band engineering for heteromeric dye foldamer}, volume = 10, year = 2024 }

  %0 Journal Article %1 Schulz_2024 %A Schulz, Alexander %A Fröhlich, Rebecca %A Jayachandran, Ajay %A Schneider, Franziska %A Stolte, Matthias %A Brixner, Tobias %A Würthner, Frank %D 2024 %I Elsevier BV %J Chem %N 9 %P 2887-2900 %R 10.1016/j.chempr.2024.05.023 %T Panchromatic light-harvesting antenna by supramolecular exciton band engineering for heteromeric dye foldamer %U http://dx.doi.org/10.1016/j.chempr.2024.05.023 %V 10 %X Natural photosystems accomplish panchromatic light absorption by different chromophores that are non-covalently embedded in protein matrices and mostly lack close dye-dye interactions. In this article, we introduce a light-harvesting (LH) system established by four different merocyanine dyes that are co-facially stacked by dipole-dipole interactions and a peptide-like backbone in a folded heteromer architecture to afford a panchromatic absorption band consisting of several strongly coupled exciton states. This exciton manifold allows for ultrafast and efficient energy transport in the artificial antenna. Furthermore, due to the tight stacking of the dyes in their folded state, non-radiative processes are slowed down, thereby increasing the lifetime of the excited state and the fluorescence quantum yield from <3% for the individual dyes up to 38% for the folda-heteromer. Together with the panchromatic absorption, this leads to a substantial improvement of the fluorescence brightness upon broadband excitation in comparison with its constituent chromophores.
• Diboraperylene Diborinic Acid Self‐Assembly on Ag(111)—Kagome Flat Band Localized States Imaged by Scanning Tunneling Microscopy and Spectroscopy. Pan, Wun‐Chang; Mützel, Carina; Haldar, Soumyajyoti; Hohmann, Hendrik; Heinze, Stefan; Farrell, Jeffrey M.; Thomale, Ronny; Bode, Matthias; Würthner, Frank; Qi, Jing. In Angew. Chem. Int. Ed., 63(15). 2024.
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  Replacement of sp2-hybridized carbon in polycyclic aromatic hydrocarbons (PAHs) by boron affords electron-deficient π-scaffolds due to the vacant pz-orbital of three-coordinate boron with the potential for pronounced electronic interactions with electron-rich metal surfaces. Using a diboraperylene diborinic acid derivative as precursor and a controlled on-surface non-covalent synthesis approach, we report on a self-assembled chiral supramolecular kagome network on an Ag(111) surface stabilized by intermolecular hydrogen-bonding interactions at low temperature. Scanning tunneling microscopy (STM) and spectroscopy (STS) reveal a flat band at ca. 0.33 eV above the Fermi level which is localized at the molecule center, in good agreement with tight-binding model calculations of flat bands characteristic for kagome lattices.

  @article{Pan_2024, abstract = {Replacement of sp2-hybridized carbon in polycyclic aromatic hydrocarbons (PAHs) by boron affords electron-deficient π-scaffolds due to the vacant pz-orbital of three-coordinate boron with the potential for pronounced electronic interactions with electron-rich metal surfaces. Using a diboraperylene diborinic acid derivative as precursor and a controlled on-surface non-covalent synthesis approach, we report on a self-assembled chiral supramolecular kagome network on an Ag(111) surface stabilized by intermolecular hydrogen-bonding interactions at low temperature. Scanning tunneling microscopy (STM) and spectroscopy (STS) reveal a flat band at ca. 0.33 eV above the Fermi level which is localized at the molecule center, in good agreement with tight-binding model calculations of flat bands characteristic for kagome lattices.}, author = {Pan, Wun‐Chang and Mützel, Carina and Haldar, Soumyajyoti and Hohmann, Hendrik and Heinze, Stefan and Farrell, Jeffrey M. and Thomale, Ronny and Bode, Matthias and Würthner, Frank and Qi, Jing}, journal = {Angew. Chem. Int. Ed.}, keywords = {myown}, month = {02}, number = 15, publisher = {Wiley}, title = {Diboraperylene Diborinic Acid Self‐Assembly on Ag(111)—Kagome Flat Band Localized States Imaged by Scanning Tunneling Microscopy and Spectroscopy}, volume = 63, year = 2024 }

  %0 Journal Article %1 Pan_2024 %A Pan, Wun‐Chang %A Mützel, Carina %A Haldar, Soumyajyoti %A Hohmann, Hendrik %A Heinze, Stefan %A Farrell, Jeffrey M. %A Thomale, Ronny %A Bode, Matthias %A Würthner, Frank %A Qi, Jing %D 2024 %I Wiley %J Angew. Chem. Int. Ed. %N 15 %R 10.1002/anie.202400313 %T Diboraperylene Diborinic Acid Self‐Assembly on Ag(111)—Kagome Flat Band Localized States Imaged by Scanning Tunneling Microscopy and Spectroscopy %U http://dx.doi.org/10.1002/anie.202400313 %V 63 %X Replacement of sp2-hybridized carbon in polycyclic aromatic hydrocarbons (PAHs) by boron affords electron-deficient π-scaffolds due to the vacant pz-orbital of three-coordinate boron with the potential for pronounced electronic interactions with electron-rich metal surfaces. Using a diboraperylene diborinic acid derivative as precursor and a controlled on-surface non-covalent synthesis approach, we report on a self-assembled chiral supramolecular kagome network on an Ag(111) surface stabilized by intermolecular hydrogen-bonding interactions at low temperature. Scanning tunneling microscopy (STM) and spectroscopy (STS) reveal a flat band at ca. 0.33 eV above the Fermi level which is localized at the molecule center, in good agreement with tight-binding model calculations of flat bands characteristic for kagome lattices.
• Mutual induced fit transition structure stabilization of corannulene’s bowl-to-bowl inversion in a perylene bisimide cyclophane. Weh, Manuel; Kroeger, Asja A.; Anhalt, Olga; Karton, Amir; Würthner, Frank. In Chem. Sci., 15(2), pp. 609–617. 2024.
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  Corannulene is known to undergo a fast bowl-to-bowl inversion at r.t. via a planar transition structure (TS). Herein we present the catalysis of this process within a perylene bisimide (PBI) cyclophane composed of chirally twisted, non-planar chromophores, linked by para-xylylene spacers. Variable temperature NMR studies reveal that the bowl-to-bowl inversion is significantly accelerated within the cyclophane template despite the structural non-complementarity between the binding site of the host and the TS of the guest. The observed acceleration corresponds to a decrease in the bowl-to-bowl inversion barrier of 11.6 kJ mol−1 compared to the uncatalyzed process. Comparative binding studies for corannulene (20 π-electrons) and other planar polycyclic aromatic hydrocarbons (PAHs) with 14 to 24 π-electrons were applied to rationalize this barrier reduction. They revealed high binding constants that reach, in tetrachloromethane as a solvent, the picomolar range for the largest guest coronene. Computational models corroborate these experimental results and suggest that both TS stabilization and ground state destabilization contribute to the observed catalytic effect. Hereby, we find a “mutual induced fit” between host and guest in the TS complex, such that mutual geometric adaptation of the energetically favored planar TS and curved π-systems of the host results in an unprecedented non-planar TS of corannulene. Concomitant partial planarization of the PBI units optimizes noncovalent TS stabilization by π–π stacking interactions. This observation of a “mutual induced fit” in the TS of a host–guest complex was further validated experimentally by single crystal X-ray analysis of a host–guest complex with coronene as a qualitative transition state analogue.

  @article{D3SC05341E, abstract = {Corannulene is known to undergo a fast bowl-to-bowl inversion at r.t. via a planar transition structure (TS). Herein we present the catalysis of this process within a perylene bisimide (PBI) cyclophane composed of chirally twisted{,} non-planar chromophores{,} linked by para-xylylene spacers. Variable temperature NMR studies reveal that the bowl-to-bowl inversion is significantly accelerated within the cyclophane template despite the structural non-complementarity between the binding site of the host and the TS of the guest. The observed acceleration corresponds to a decrease in the bowl-to-bowl inversion barrier of 11.6 kJ mol−1 compared to the uncatalyzed process. Comparative binding studies for corannulene (20 π-electrons) and other planar polycyclic aromatic hydrocarbons (PAHs) with 14 to 24 π-electrons were applied to rationalize this barrier reduction. They revealed high binding constants that reach{,} in tetrachloromethane as a solvent{,} the picomolar range for the largest guest coronene. Computational models corroborate these experimental results and suggest that both TS stabilization and ground state destabilization contribute to the observed catalytic effect. Hereby{,} we find a “mutual induced fit” between host and guest in the TS complex{,} such that mutual geometric adaptation of the energetically favored planar TS and curved π-systems of the host results in an unprecedented non-planar TS of corannulene. Concomitant partial planarization of the PBI units optimizes noncovalent TS stabilization by π–π stacking interactions. This observation of a “mutual induced fit” in the TS of a host–guest complex was further validated experimentally by single crystal X-ray analysis of a host–guest complex with coronene as a qualitative transition state analogue.}, author = {Weh, Manuel and Kroeger, Asja A. and Anhalt, Olga and Karton, Amir and Würthner, Frank}, journal = {Chem. Sci.}, keywords = {myown}, number = 2, pages = {609-617}, title = {Mutual induced fit transition structure stabilization of corannulene's bowl-to-bowl inversion in a perylene bisimide cyclophane}, volume = 15, year = 2024 }

  %0 Journal Article %1 D3SC05341E %A Weh, Manuel %A Kroeger, Asja A. %A Anhalt, Olga %A Karton, Amir %A Würthner, Frank %D 2024 %J Chem. Sci. %N 2 %P 609-617 %R 10.1039/D3SC05341E %T Mutual induced fit transition structure stabilization of corannulene's bowl-to-bowl inversion in a perylene bisimide cyclophane %U http://dx.doi.org/10.1039/D3SC05341E %V 15 %X Corannulene is known to undergo a fast bowl-to-bowl inversion at r.t. via a planar transition structure (TS). Herein we present the catalysis of this process within a perylene bisimide (PBI) cyclophane composed of chirally twisted, non-planar chromophores, linked by para-xylylene spacers. Variable temperature NMR studies reveal that the bowl-to-bowl inversion is significantly accelerated within the cyclophane template despite the structural non-complementarity between the binding site of the host and the TS of the guest. The observed acceleration corresponds to a decrease in the bowl-to-bowl inversion barrier of 11.6 kJ mol−1 compared to the uncatalyzed process. Comparative binding studies for corannulene (20 π-electrons) and other planar polycyclic aromatic hydrocarbons (PAHs) with 14 to 24 π-electrons were applied to rationalize this barrier reduction. They revealed high binding constants that reach, in tetrachloromethane as a solvent, the picomolar range for the largest guest coronene. Computational models corroborate these experimental results and suggest that both TS stabilization and ground state destabilization contribute to the observed catalytic effect. Hereby, we find a “mutual induced fit” between host and guest in the TS complex, such that mutual geometric adaptation of the energetically favored planar TS and curved π-systems of the host results in an unprecedented non-planar TS of corannulene. Concomitant partial planarization of the PBI units optimizes noncovalent TS stabilization by π–π stacking interactions. This observation of a “mutual induced fit” in the TS of a host–guest complex was further validated experimentally by single crystal X-ray analysis of a host–guest complex with coronene as a qualitative transition state analogue.
• A highly fluorescent bora[6]helicene exhibiting circularly polarized light emission. Schnitzlein, Matthias; Shoyama, Kazutaka; Würthner, Frank. In Chem. Sci., 15(8), pp. 2984–2989. 2024.
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  Heteroatom-doped helicenes have attracted great research interest due to their inherent chirality enabling fascinating new applications. Herein we present our successful synthesis of 19c-boratribenzo[gh,jk,mn][6]helicene, the hitherto longest and first configurationally stable pristine bora[n]helicene. It displays intense orange fluorescence and circularly polarized light (CPL) emission with a high quantum yield of up to 84%. X-ray single crystal analysis reveals a highly twisted, helical shape and intriguing intermolecular stacking. Complexation with a size-complemental aza[4]helicene yielded an unprecedented hetero-chiral π–π-stacked helicene dimer.

  @article{D3SC05171D, abstract = {Heteroatom-doped helicenes have attracted great research interest due to their inherent chirality enabling fascinating new applications. Herein we present our successful synthesis of 19c-boratribenzo[gh{,}jk{,}mn][6]helicene{,} the hitherto longest and first configurationally stable pristine bora[n]helicene. It displays intense orange fluorescence and circularly polarized light (CPL) emission with a high quantum yield of up to 84%. X-ray single crystal analysis reveals a highly twisted{,} helical shape and intriguing intermolecular stacking. Complexation with a size-complemental aza[4]helicene yielded an unprecedented hetero-chiral π–π-stacked helicene dimer.}, author = {Schnitzlein, Matthias and Shoyama, Kazutaka and Würthner, Frank}, journal = {Chem. Sci.}, keywords = {myown}, number = 8, pages = {2984-2989}, publisher = {The Royal Society of Chemistry}, title = {A highly fluorescent bora[6]helicene exhibiting circularly polarized light emission}, volume = 15, year = 2024 }

  %0 Journal Article %1 D3SC05171D %A Schnitzlein, Matthias %A Shoyama, Kazutaka %A Würthner, Frank %D 2024 %I The Royal Society of Chemistry %J Chem. Sci. %N 8 %P 2984-2989 %R 10.1039/D3SC05171D %T A highly fluorescent bora[6]helicene exhibiting circularly polarized light emission %U http://dx.doi.org/10.1039/D3SC05171D %V 15 %X Heteroatom-doped helicenes have attracted great research interest due to their inherent chirality enabling fascinating new applications. Herein we present our successful synthesis of 19c-boratribenzo[gh,jk,mn][6]helicene, the hitherto longest and first configurationally stable pristine bora[n]helicene. It displays intense orange fluorescence and circularly polarized light (CPL) emission with a high quantum yield of up to 84%. X-ray single crystal analysis reveals a highly twisted, helical shape and intriguing intermolecular stacking. Complexation with a size-complemental aza[4]helicene yielded an unprecedented hetero-chiral π–π-stacked helicene dimer.
• Sequential Synthesis and Secondary Structure Analysis of Two Classes of Perylene Bisimide Oligomers. Teichmann, Ben; Liu, Bin; Hirsch, Marcel; Dubey, Rajeev K.; Würthner, Frank. In Org. Lett., 26(26), pp. 5544–5548. 2024.
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  An iterative step-by-step synthetic approach is employed to form perylene bisimide (PBI) oligomers of defined sizes by connecting the PBI units through their imide positions via a benzyl linker. The versatility of this approach was showcased by its successful implementation on two different PBI building blocks to achieve two separate series of oligomers (up to the pentamer) with modulated conformations: one with an open random coil oligomer and one with an H-type foldamer architecture.

  @article{Teichmann_2024, abstract = {An iterative step-by-step synthetic approach is employed to form perylene bisimide (PBI) oligomers of defined sizes by connecting the PBI units through their imide positions via a benzyl linker. The versatility of this approach was showcased by its successful implementation on two different PBI building blocks to achieve two separate series of oligomers (up to the pentamer) with modulated conformations: one with an open random coil oligomer and one with an H-type foldamer architecture.}, author = {Teichmann, Ben and Liu, Bin and Hirsch, Marcel and Dubey, Rajeev K. and Würthner, Frank}, journal = {Org. Lett.}, keywords = {myown}, month = {06}, number = 26, pages = {5544–5548}, publisher = {American Chemical Society (ACS)}, title = {Sequential Synthesis and Secondary Structure Analysis of Two Classes of Perylene Bisimide Oligomers}, volume = 26, year = 2024 }

  %0 Journal Article %1 Teichmann_2024 %A Teichmann, Ben %A Liu, Bin %A Hirsch, Marcel %A Dubey, Rajeev K. %A Würthner, Frank %D 2024 %I American Chemical Society (ACS) %J Org. Lett. %N 26 %P 5544–5548 %R 10.1021/acs.orglett.4c01928 %T Sequential Synthesis and Secondary Structure Analysis of Two Classes of Perylene Bisimide Oligomers %U http://dx.doi.org/10.1021/acs.orglett.4c01928 %V 26 %X An iterative step-by-step synthetic approach is employed to form perylene bisimide (PBI) oligomers of defined sizes by connecting the PBI units through their imide positions via a benzyl linker. The versatility of this approach was showcased by its successful implementation on two different PBI building blocks to achieve two separate series of oligomers (up to the pentamer) with modulated conformations: one with an open random coil oligomer and one with an H-type foldamer architecture.
• Dynamics of reduced perylene bisimide cyclophane redox species by ultrafast spectroelectrochemistry. Fröhlich, Rebecca; Rühe, Jessica; Moos, Michael; Kontschak, Laura; Ehrmann, Patrik; Würthner, Frank; Lambert, Christoph; Brixner, Tobias. In J. Chem. Phys., 160(23). 2024.
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  Charged molecules play essential roles in many natural and artificial functional processes, ranging from photosynthesis to photovoltaics to chemical reactions and more. It is often difficult to identify the optical dynamic properties of relevant redox species because they cannot be easily prepared, their spectra overlap, or they evolve on a femtosecond timescale. Here, we address these challenges by combining spec- troelectrochemistry, ultrafast transient absorption spectroscopy, and suitable data analysis. We illustrate the method with the various redox species of a cyclophane composed of two perylene bisimide subunits. While singular-value decomposition is a well-established tool in the analysis of time-dependent spectra of a single molecular species, we here use it additionally to separate transient maps of individual redox species. This is relevant because at any specific applied electrochemical potential, several redox species coexist in the ensemble, and our pro- cedure allows disentangling their spectroscopic response. In the second step, global analysis is then employed to retrieve the excited-state lifetimes and decay-associated difference spectra. Our approach is generally suitable for unraveling ultrafast dynamics in materials featuring charge-transfer processes.

  @article{Fr_hlich_2024, abstract = {Charged molecules play essential roles in many natural and artificial functional processes, ranging from photosynthesis to photovoltaics to chemical reactions and more. It is often difficult to identify the optical dynamic properties of relevant redox species because they cannot be easily prepared, their spectra overlap, or they evolve on a femtosecond timescale. Here, we address these challenges by combining spec- troelectrochemistry, ultrafast transient absorption spectroscopy, and suitable data analysis. We illustrate the method with the various redox species of a cyclophane composed of two perylene bisimide subunits. While singular-value decomposition is a well-established tool in the analysis of time-dependent spectra of a single molecular species, we here use it additionally to separate transient maps of individual redox species. This is relevant because at any specific applied electrochemical potential, several redox species coexist in the ensemble, and our pro- cedure allows disentangling their spectroscopic response. In the second step, global analysis is then employed to retrieve the excited-state lifetimes and decay-associated difference spectra. Our approach is generally suitable for unraveling ultrafast dynamics in materials featuring charge-transfer processes.}, author = {Fröhlich, Rebecca and Rühe, Jessica and Moos, Michael and Kontschak, Laura and Ehrmann, Patrik and Würthner, Frank and Lambert, Christoph and Brixner, Tobias}, journal = {J. Chem. Phys.}, keywords = {myown}, month = {06}, number = 23, publisher = {AIP Publishing}, title = {Dynamics of reduced perylene bisimide cyclophane redox species by ultrafast spectroelectrochemistry}, volume = 160, year = 2024 }

  %0 Journal Article %1 Fr_hlich_2024 %A Fröhlich, Rebecca %A Rühe, Jessica %A Moos, Michael %A Kontschak, Laura %A Ehrmann, Patrik %A Würthner, Frank %A Lambert, Christoph %A Brixner, Tobias %D 2024 %I AIP Publishing %J J. Chem. Phys. %N 23 %R 10.1063/5.0210490 %T Dynamics of reduced perylene bisimide cyclophane redox species by ultrafast spectroelectrochemistry %U http://dx.doi.org/10.1063/5.0210490 %V 160 %X Charged molecules play essential roles in many natural and artificial functional processes, ranging from photosynthesis to photovoltaics to chemical reactions and more. It is often difficult to identify the optical dynamic properties of relevant redox species because they cannot be easily prepared, their spectra overlap, or they evolve on a femtosecond timescale. Here, we address these challenges by combining spec- troelectrochemistry, ultrafast transient absorption spectroscopy, and suitable data analysis. We illustrate the method with the various redox species of a cyclophane composed of two perylene bisimide subunits. While singular-value decomposition is a well-established tool in the analysis of time-dependent spectra of a single molecular species, we here use it additionally to separate transient maps of individual redox species. This is relevant because at any specific applied electrochemical potential, several redox species coexist in the ensemble, and our pro- cedure allows disentangling their spectroscopic response. In the second step, global analysis is then employed to retrieve the excited-state lifetimes and decay-associated difference spectra. Our approach is generally suitable for unraveling ultrafast dynamics in materials featuring charge-transfer processes.
• 2,3 : 6,7‐Naphthalene Bis(dicarboximide) Cyclophane: A Photofunctional Host for Ambient Delayed Fluorescence in Solution. Garain, Swadhin; Li, Pei‐Lun; Shoyama, Kazutaka; Würthner, Frank. In Angew. Chem. Int. Ed., 63(43). 2024.
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  Harvesting triplet excitons of heavy atom-free purely organic chromophores under aerated conditions is challenging due to the quenching of long-lived triplet states by molecular oxygen and vibrational dissipation. Herein, we show a supramolecular approach of triplet harvesting via mitigating quenching pathways of a triplet harvester. Specifically, we used a host–guest system based on 2,3 : 6,7-naphthalene bis(dicarboximide)-derived cyclophane (NBICy) and carbazole derivative (EtCz). Complexation studies and single-crystal X-ray analysis showed the formation of a rigid host–guest complex (K≈104 M−1 in CCl4), resulting in triplet-exciton stabilization under aerated conditions via mitigating vibrational interference and oxygen quenching. Photophysical studies elucidate the delayed fluorescence emission from the charge-transfer state (1CT) with a quantum yield (QY) of 6–8 % under ambient conditions which increased up to 36 % in an inert atmosphere.

  @article{Garain_2024, abstract = {Harvesting triplet excitons of heavy atom-free purely organic chromophores under aerated conditions is challenging due to the quenching of long-lived triplet states by molecular oxygen and vibrational dissipation. Herein, we show a supramolecular approach of triplet harvesting via mitigating quenching pathways of a triplet harvester. Specifically, we used a host–guest system based on 2,3 : 6,7-naphthalene bis(dicarboximide)-derived cyclophane (NBICy) and carbazole derivative (EtCz). Complexation studies and single-crystal X-ray analysis showed the formation of a rigid host–guest complex (K≈104 M−1 in CCl4), resulting in triplet-exciton stabilization under aerated conditions via mitigating vibrational interference and oxygen quenching. Photophysical studies elucidate the delayed fluorescence emission from the charge-transfer state (1CT) with a quantum yield (QY) of 6–8 % under ambient conditions which increased up to 36 % in an inert atmosphere.}, author = {Garain, Swadhin and Li, Pei‐Lun and Shoyama, Kazutaka and Würthner, Frank}, journal = {Angew. Chem. Int. Ed.}, keywords = {myown}, month = {09}, number = 43, publisher = {Wiley}, title = {2,3 : 6,7‐Naphthalene Bis(dicarboximide) Cyclophane: A Photofunctional Host for Ambient Delayed Fluorescence in Solution}, volume = 63, year = 2024 }

  %0 Journal Article %1 Garain_2024 %A Garain, Swadhin %A Li, Pei‐Lun %A Shoyama, Kazutaka %A Würthner, Frank %D 2024 %I Wiley %J Angew. Chem. Int. Ed. %N 43 %R 10.1002/anie.202411102 %T 2,3 : 6,7‐Naphthalene Bis(dicarboximide) Cyclophane: A Photofunctional Host for Ambient Delayed Fluorescence in Solution %U http://dx.doi.org/10.1002/anie.202411102 %V 63 %X Harvesting triplet excitons of heavy atom-free purely organic chromophores under aerated conditions is challenging due to the quenching of long-lived triplet states by molecular oxygen and vibrational dissipation. Herein, we show a supramolecular approach of triplet harvesting via mitigating quenching pathways of a triplet harvester. Specifically, we used a host–guest system based on 2,3 : 6,7-naphthalene bis(dicarboximide)-derived cyclophane (NBICy) and carbazole derivative (EtCz). Complexation studies and single-crystal X-ray analysis showed the formation of a rigid host–guest complex (K≈104 M−1 in CCl4), resulting in triplet-exciton stabilization under aerated conditions via mitigating vibrational interference and oxygen quenching. Photophysical studies elucidate the delayed fluorescence emission from the charge-transfer state (1CT) with a quantum yield (QY) of 6–8 % under ambient conditions which increased up to 36 % in an inert atmosphere.
• A Water-Stable Boronate Ester Cage. Kirchner, Philipp H.; Schramm, Louis; Ivanova, Svetlana; Shoyama, Kazutaka; Würthner, Frank; Beuerle, Florian. In J. Am. Chem. Soc., 146(8), pp. 5305–5315. 2024.
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  The reversible condensation of catechols and boronic acids to boronate esters is a paradigm reaction in dynamic covalent chemistry. However, facile backward hydrolysis is detrimental for stability and has so far prevented applications for boronate-based materials. Here, we introduce cubic boronate ester cages 6 derived from hexahydroxy tribenzotriquinacenes and phenylene diboronic acids with ortho-t-butyl substituents. Due to steric shielding, dynamic exchange at the Lewis acidic boron sites is feasible only under acid or base catalysis but fully prevented at neutral conditions. For the first time, boronate ester cages 6 tolerate substantial amounts of water or alcohols both in solution and solid state. The unprecedented applicability of these materials under ambient and aqueous conditions is showcased by efficient encapsulation and on-demand release of β-carotene dyes and heterogeneous water oxidation catalysis after the encapsulation of ruthenium catalysts.

  @article{Kirchner_2024, abstract = {The reversible condensation of catechols and boronic acids to boronate esters is a paradigm reaction in dynamic covalent chemistry. However, facile backward hydrolysis is detrimental for stability and has so far prevented applications for boronate-based materials. Here, we introduce cubic boronate ester cages 6 derived from hexahydroxy tribenzotriquinacenes and phenylene diboronic acids with ortho-t-butyl substituents. Due to steric shielding, dynamic exchange at the Lewis acidic boron sites is feasible only under acid or base catalysis but fully prevented at neutral conditions. For the first time, boronate ester cages 6 tolerate substantial amounts of water or alcohols both in solution and solid state. The unprecedented applicability of these materials under ambient and aqueous conditions is showcased by efficient encapsulation and on-demand release of β-carotene dyes and heterogeneous water oxidation catalysis after the encapsulation of ruthenium catalysts.}, author = {Kirchner, Philipp H. and Schramm, Louis and Ivanova, Svetlana and Shoyama, Kazutaka and Würthner, Frank and Beuerle, Florian}, journal = {J. Am. Chem. Soc.}, keywords = {myown}, month = {02}, number = 8, pages = {5305–5315}, publisher = {American Chemical Society (ACS)}, title = {A Water-Stable Boronate Ester Cage}, volume = 146, year = 2024 }

  %0 Journal Article %1 Kirchner_2024 %A Kirchner, Philipp H. %A Schramm, Louis %A Ivanova, Svetlana %A Shoyama, Kazutaka %A Würthner, Frank %A Beuerle, Florian %D 2024 %I American Chemical Society (ACS) %J J. Am. Chem. Soc. %N 8 %P 5305–5315 %R 10.1021/jacs.3c12002 %T A Water-Stable Boronate Ester Cage %U http://dx.doi.org/10.1021/jacs.3c12002 %V 146 %X The reversible condensation of catechols and boronic acids to boronate esters is a paradigm reaction in dynamic covalent chemistry. However, facile backward hydrolysis is detrimental for stability and has so far prevented applications for boronate-based materials. Here, we introduce cubic boronate ester cages 6 derived from hexahydroxy tribenzotriquinacenes and phenylene diboronic acids with ortho-t-butyl substituents. Due to steric shielding, dynamic exchange at the Lewis acidic boron sites is feasible only under acid or base catalysis but fully prevented at neutral conditions. For the first time, boronate ester cages 6 tolerate substantial amounts of water or alcohols both in solution and solid state. The unprecedented applicability of these materials under ambient and aqueous conditions is showcased by efficient encapsulation and on-demand release of β-carotene dyes and heterogeneous water oxidation catalysis after the encapsulation of ruthenium catalysts.
• Bioinspired Water Preorganization in Confined Space for Efficient Water Oxidation Catalysis in Metallosupramolecular Ruthenium Architectures. Noll, Niklas; Würthner, Frank. In Acc. Chem. Res., 57(10), pp. 1538–1549. 2024.
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  CONSPECTUS: Nature has established a sustainable way to maintain aerobic life on earth by inventing one of the most sophisticated biological processes, namely, natural photosynthesis, which delivers us with organic matter and molecular oxygen derived from the two abundant resources sunlight and water. The thermodynamically demanding photosynthetic water splitting is catalyzed by the oxygen-evolving complex in photosystem II (OEC-PSII), which comprises a distorted tetramanganese−calcium cluster (CaMn4O5) as catalytic core. As an ubiquitous concept for fine-tuning and regulating the reactivity of the active site of metalloenzymes, the surrounding protein domain creates a sophisticated environment that promotes substrate preorganization through secondary, noncovalent interactions such as hydrogen bonding or electrostatic interactions. Based on the high-resolution X-ray structure of PSII, several water channels were identified near the active site, which are filled with extensive hydrogen-bonding networks of preorganized water molecules, connecting the OEC with the protein surface. As an integral part of the outer coordination sphere of natural metalloenzymes, these channels control the substrate and product delivery, carefully regulate the proton flow by promoting pivotal proton-coupled electron transfer processes, and simultaneously stabilize short-lived oxidized intermediates, thus highlighting the importance of an ordered water network for the remarkable efficiency of the natural OEC. Transferring this concept from nature to the engineering of artificial metal catalysts for fuel production has fostered the fascinating field of metallosupramolecular chemistry by generating defined cavities that conceptually mimic enzymatic pockets. However, the application of supramolecular approaches to generate artificial water oxidation catalysts remained scarce prior to our initial reports, since such molecular design strategies for efficient activation of substrate water molecules in confined nanoenvironments were lacking. In this Account, we describe our research efforts on combining the state-of-the art Ru(bda) catalytic framework with structurally programmed ditopic ligands to guide the water oxidation process in defined metallosupramolecular assemblies in spatial proximity. We will elucidate the governing factors that control the quality of hydrogen-bonding water networks in multinuclear cavities of varying sizes and geometries to obtain high-performance, state-of-the-art water oxidation catalysts. Pushing the boundaries of artificial catalyst design, embedding a single catalytic Ru center into a well-defined molecular pocket enabled sophisticated water preorganization in front of the active site through an encoded basic recognition site, resulting in high catalytic rates comparable to those of the natural counterpart OEC-PSII. To fully explore their potential for solar fuel devices, the suitability of our metallosupramolecular assemblies was demonstrated under (electro)chemical and photocatalytic water oxidation conditions. In addition, testing the limits of structural diversity allowed the fabrication of self-assembled linear coordination oligomers as novel photocatalytic materials and long-range ordered covalent organic framework (COF) materials as recyclable and long-term stable solid-state materials for future applications.

  @article{Noll_2024, abstract = {CONSPECTUS: Nature has established a sustainable way to maintain aerobic life on earth by inventing one of the most sophisticated biological processes, namely, natural photosynthesis, which delivers us with organic matter and molecular oxygen derived from the two abundant resources sunlight and water. The thermodynamically demanding photosynthetic water splitting is catalyzed by the oxygen-evolving complex in photosystem II (OEC-PSII), which comprises a distorted tetramanganese−calcium cluster (CaMn4O5) as catalytic core. As an ubiquitous concept for fine-tuning and regulating the reactivity of the active site of metalloenzymes, the surrounding protein domain creates a sophisticated environment that promotes substrate preorganization through secondary, noncovalent interactions such as hydrogen bonding or electrostatic interactions. Based on the high-resolution X-ray structure of PSII, several water channels were identified near the active site, which are filled with extensive hydrogen-bonding networks of preorganized water molecules, connecting the OEC with the protein surface. As an integral part of the outer coordination sphere of natural metalloenzymes, these channels control the substrate and product delivery, carefully regulate the proton flow by promoting pivotal proton-coupled electron transfer processes, and simultaneously stabilize short-lived oxidized intermediates, thus highlighting the importance of an ordered water network for the remarkable efficiency of the natural OEC. Transferring this concept from nature to the engineering of artificial metal catalysts for fuel production has fostered the fascinating field of metallosupramolecular chemistry by generating defined cavities that conceptually mimic enzymatic pockets. However, the application of supramolecular approaches to generate artificial water oxidation catalysts remained scarce prior to our initial reports, since such molecular design strategies for efficient activation of substrate water molecules in confined nanoenvironments were lacking. In this Account, we describe our research efforts on combining the state-of-the art Ru(bda) catalytic framework with structurally programmed ditopic ligands to guide the water oxidation process in defined metallosupramolecular assemblies in spatial proximity. We will elucidate the governing factors that control the quality of hydrogen-bonding water networks in multinuclear cavities of varying sizes and geometries to obtain high-performance, state-of-the-art water oxidation catalysts. Pushing the boundaries of artificial catalyst design, embedding a single catalytic Ru center into a well-defined molecular pocket enabled sophisticated water preorganization in front of the active site through an encoded basic recognition site, resulting in high catalytic rates comparable to those of the natural counterpart OEC-PSII. To fully explore their potential for solar fuel devices, the suitability of our metallosupramolecular assemblies was demonstrated under (electro)chemical and photocatalytic water oxidation conditions. In addition, testing the limits of structural diversity allowed the fabrication of self-assembled linear coordination oligomers as novel photocatalytic materials and long-range ordered covalent organic framework (COF) materials as recyclable and long-term stable solid-state materials for future applications.}, author = {Noll, Niklas and Würthner, Frank}, journal = {Acc. Chem. Res.}, keywords = {myown}, month = {05}, number = 10, pages = {1538–1549}, publisher = {American Chemical Society (ACS)}, title = {Bioinspired Water Preorganization in Confined Space for Efficient Water Oxidation Catalysis in Metallosupramolecular Ruthenium Architectures}, volume = 57, year = 2024 }

  %0 Journal Article %1 Noll_2024 %A Noll, Niklas %A Würthner, Frank %D 2024 %I American Chemical Society (ACS) %J Acc. Chem. Res. %N 10 %P 1538–1549 %R 10.1021/acs.accounts.4c00148 %T Bioinspired Water Preorganization in Confined Space for Efficient Water Oxidation Catalysis in Metallosupramolecular Ruthenium Architectures %U http://dx.doi.org/10.1021/acs.accounts.4c00148 %V 57 %X CONSPECTUS: Nature has established a sustainable way to maintain aerobic life on earth by inventing one of the most sophisticated biological processes, namely, natural photosynthesis, which delivers us with organic matter and molecular oxygen derived from the two abundant resources sunlight and water. The thermodynamically demanding photosynthetic water splitting is catalyzed by the oxygen-evolving complex in photosystem II (OEC-PSII), which comprises a distorted tetramanganese−calcium cluster (CaMn4O5) as catalytic core. As an ubiquitous concept for fine-tuning and regulating the reactivity of the active site of metalloenzymes, the surrounding protein domain creates a sophisticated environment that promotes substrate preorganization through secondary, noncovalent interactions such as hydrogen bonding or electrostatic interactions. Based on the high-resolution X-ray structure of PSII, several water channels were identified near the active site, which are filled with extensive hydrogen-bonding networks of preorganized water molecules, connecting the OEC with the protein surface. As an integral part of the outer coordination sphere of natural metalloenzymes, these channels control the substrate and product delivery, carefully regulate the proton flow by promoting pivotal proton-coupled electron transfer processes, and simultaneously stabilize short-lived oxidized intermediates, thus highlighting the importance of an ordered water network for the remarkable efficiency of the natural OEC. Transferring this concept from nature to the engineering of artificial metal catalysts for fuel production has fostered the fascinating field of metallosupramolecular chemistry by generating defined cavities that conceptually mimic enzymatic pockets. However, the application of supramolecular approaches to generate artificial water oxidation catalysts remained scarce prior to our initial reports, since such molecular design strategies for efficient activation of substrate water molecules in confined nanoenvironments were lacking. In this Account, we describe our research efforts on combining the state-of-the art Ru(bda) catalytic framework with structurally programmed ditopic ligands to guide the water oxidation process in defined metallosupramolecular assemblies in spatial proximity. We will elucidate the governing factors that control the quality of hydrogen-bonding water networks in multinuclear cavities of varying sizes and geometries to obtain high-performance, state-of-the-art water oxidation catalysts. Pushing the boundaries of artificial catalyst design, embedding a single catalytic Ru center into a well-defined molecular pocket enabled sophisticated water preorganization in front of the active site through an encoded basic recognition site, resulting in high catalytic rates comparable to those of the natural counterpart OEC-PSII. To fully explore their potential for solar fuel devices, the suitability of our metallosupramolecular assemblies was demonstrated under (electro)chemical and photocatalytic water oxidation conditions. In addition, testing the limits of structural diversity allowed the fabrication of self-assembled linear coordination oligomers as novel photocatalytic materials and long-range ordered covalent organic framework (COF) materials as recyclable and long-term stable solid-state materials for future applications.
• Polarized, color-selective and semi-transparent organic photodiode of aligned merocyanine H-aggregates. Schembri, Tim; Kolb, Leonhard; Stolte, Matthias; Würthner, Frank. In J. Mater. Chem. C, 12(14), pp. 4948–4953. 2024.
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  Highly anisotropic thin films of H-type coupled dipolar merocyanines with large dichroic ratios of over 50 were deposited by solution shearing. These layers were incorporated into simultaneously color- and polarization-selective organic photodiodes. Using a transparent non-fullerene acceptor, polarization-sensitive planar-heterojunction devices with an average visible transmittance of 93% were obtained.

  @article{D4TC00678J, abstract = {Highly anisotropic thin films of H-type coupled dipolar merocyanines with large dichroic ratios of over 50 were deposited by solution shearing. These layers were incorporated into simultaneously color- and polarization-selective organic photodiodes. Using a transparent non-fullerene acceptor{,} polarization-sensitive planar-heterojunction devices with an average visible transmittance of 93% were obtained.}, author = {Schembri, Tim and Kolb, Leonhard and Stolte, Matthias and Würthner, Frank}, journal = {J. Mater. Chem. C}, keywords = {myown}, number = 14, pages = {4948-4953}, publisher = {The Royal Society of Chemistry}, title = {Polarized{,} color-selective and semi-transparent organic photodiode of aligned merocyanine H-aggregates}, volume = 12, year = 2024 }

  %0 Journal Article %1 D4TC00678J %A Schembri, Tim %A Kolb, Leonhard %A Stolte, Matthias %A Würthner, Frank %D 2024 %I The Royal Society of Chemistry %J J. Mater. Chem. C %N 14 %P 4948-4953 %R 10.1039/D4TC00678J %T Polarized, color-selective and semi-transparent organic photodiode of aligned merocyanine H-aggregates %U http://dx.doi.org/10.1039/D4TC00678J %V 12 %X Highly anisotropic thin films of H-type coupled dipolar merocyanines with large dichroic ratios of over 50 were deposited by solution shearing. These layers were incorporated into simultaneously color- and polarization-selective organic photodiodes. Using a transparent non-fullerene acceptor, polarization-sensitive planar-heterojunction devices with an average visible transmittance of 93% were obtained.
• Dissymmetrical Chiral Peropyrenes: Synthesis via Iridium-Catalyzed C–H Activation/Alkyne Benzannulation and Study of Their Properties. George, Stephen P.; Spengler, Jonas; Malone, Ryan J.; Krzoska, James; Würthner, Frank; Chalifoux, Wesley A. In J. Org. Chem., 89(7), pp. 5159–5163. 2024.
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  Dissymmetrical chiral peropyrenes with electron-rich and electron-deficient aryl substituents in the bay regions were synthesized via iridium-catalyzed C–H activation and alkyne benzannulation. The electronic properties were studied using cyclic and differential pulse voltammetry. The enantiomers were separated and exhibited high glum and gabs values in circularly polarized luminescence (CPL) and circular dichroism (CD), respectively. Variable-temperature NMR experiments were conducted on symmetrical and dissymmetrical chiral peropyrenes to compare the barrier to rotation of the aryl groups in the bay region.

  @article{George_2024, abstract = {Dissymmetrical chiral peropyrenes with electron-rich and electron-deficient aryl substituents in the bay regions were synthesized via iridium-catalyzed C–H activation and alkyne benzannulation. The electronic properties were studied using cyclic and differential pulse voltammetry. The enantiomers were separated and exhibited high glum and gabs values in circularly polarized luminescence (CPL) and circular dichroism (CD), respectively. Variable-temperature NMR experiments were conducted on symmetrical and dissymmetrical chiral peropyrenes to compare the barrier to rotation of the aryl groups in the bay region.}, author = {George, Stephen P. and Spengler, Jonas and Malone, Ryan J. and Krzoska, James and Würthner, Frank and Chalifoux, Wesley A.}, journal = {J. Org. Chem.}, keywords = {myown}, month = {03}, number = 7, pages = {5159–5163}, publisher = {American Chemical Society (ACS)}, title = {Dissymmetrical Chiral Peropyrenes: Synthesis via Iridium-Catalyzed C–H Activation/Alkyne Benzannulation and Study of Their Properties}, volume = 89, year = 2024 }

  %0 Journal Article %1 George_2024 %A George, Stephen P. %A Spengler, Jonas %A Malone, Ryan J. %A Krzoska, James %A Würthner, Frank %A Chalifoux, Wesley A. %D 2024 %I American Chemical Society (ACS) %J J. Org. Chem. %N 7 %P 5159–5163 %R 10.1021/acs.joc.3c02985 %T Dissymmetrical Chiral Peropyrenes: Synthesis via Iridium-Catalyzed C–H Activation/Alkyne Benzannulation and Study of Their Properties %U http://dx.doi.org/10.1021/acs.joc.3c02985 %V 89 %X Dissymmetrical chiral peropyrenes with electron-rich and electron-deficient aryl substituents in the bay regions were synthesized via iridium-catalyzed C–H activation and alkyne benzannulation. The electronic properties were studied using cyclic and differential pulse voltammetry. The enantiomers were separated and exhibited high glum and gabs values in circularly polarized luminescence (CPL) and circular dichroism (CD), respectively. Variable-temperature NMR experiments were conducted on symmetrical and dissymmetrical chiral peropyrenes to compare the barrier to rotation of the aryl groups in the bay region.
• A Terrylene Bisimide based Universal Host for Aromatic Guests to Derive Contact Surface‐Dependent Dispersion Energies. Rühe, Jessica; Rajeevan, Megha; Shoyama, Kazutaka; Swathi, Rotti Srinivasamurthy; Würthner, Frank. In Angew. Chem. Int. Ed., 63(17). 2024.
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  π–π interactions are among the most important intermolecular interactions in supramolecular systems. Here we determine experimentally a universal parameter for their strength that is simply based on the size of the interacting contact surfaces. Toward this goal we designed a new cyclophane based on terrylene bisimide (TBI) π-walls connected by para-xylylene spacer units. With its extended π-surface this cyclophane proved to be an excellent and universal host for the complexation of π-conjugated guests, including small and large polycyclic aromatic hydrocarbons (PAHs) as well as dye molecules. The observed binding constants range up to 108 M−1 and show a linear dependence on the 2D area size of the guest molecules. This correlation can be used for the prediction of binding constants and for the design of new host–guest systems based on the herewith derived universal Gibbs interaction energy parameter of 0.31 kJ/molÅ2 in chloroform.

  @article{R_he_2024, abstract = {π–π interactions are among the most important intermolecular interactions in supramolecular systems. Here we determine experimentally a universal parameter for their strength that is simply based on the size of the interacting contact surfaces. Toward this goal we designed a new cyclophane based on terrylene bisimide (TBI) π-walls connected by para-xylylene spacer units. With its extended π-surface this cyclophane proved to be an excellent and universal host for the complexation of π-conjugated guests, including small and large polycyclic aromatic hydrocarbons (PAHs) as well as dye molecules. The observed binding constants range up to 108 M−1 and show a linear dependence on the 2D area size of the guest molecules. This correlation can be used for the prediction of binding constants and for the design of new host–guest systems based on the herewith derived universal Gibbs interaction energy parameter of 0.31 kJ/molÅ2 in chloroform.}, author = {Rühe, Jessica and Rajeevan, Megha and Shoyama, Kazutaka and Swathi, Rotti Srinivasamurthy and Würthner, Frank}, journal = {Angew. Chem. Int. Ed.}, keywords = {myown}, month = {03}, number = 17, publisher = {Wiley}, title = {A Terrylene Bisimide based Universal Host for Aromatic Guests to Derive Contact Surface‐Dependent Dispersion Energies}, volume = 63, year = 2024 }

  %0 Journal Article %1 R_he_2024 %A Rühe, Jessica %A Rajeevan, Megha %A Shoyama, Kazutaka %A Swathi, Rotti Srinivasamurthy %A Würthner, Frank %D 2024 %I Wiley %J Angew. Chem. Int. Ed. %N 17 %R 10.1002/anie.202318451 %T A Terrylene Bisimide based Universal Host for Aromatic Guests to Derive Contact Surface‐Dependent Dispersion Energies %U http://dx.doi.org/10.1002/anie.202318451 %V 63 %X π–π interactions are among the most important intermolecular interactions in supramolecular systems. Here we determine experimentally a universal parameter for their strength that is simply based on the size of the interacting contact surfaces. Toward this goal we designed a new cyclophane based on terrylene bisimide (TBI) π-walls connected by para-xylylene spacer units. With its extended π-surface this cyclophane proved to be an excellent and universal host for the complexation of π-conjugated guests, including small and large polycyclic aromatic hydrocarbons (PAHs) as well as dye molecules. The observed binding constants range up to 108 M−1 and show a linear dependence on the 2D area size of the guest molecules. This correlation can be used for the prediction of binding constants and for the design of new host–guest systems based on the herewith derived universal Gibbs interaction energy parameter of 0.31 kJ/molÅ2 in chloroform.
• Room‐Temperature Near‐Infrared Phosphorescence from C64 Nanographene Tetraimide by π‐Stacking Complexation with Platinum Porphyrin. Niyas, M. A.; Garain, Swadhin; Shoyama, Kazutaka; Würthner, Frank. In Angew. Chem. Int. Ed., 63(33). 2024.
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  Near-Infrared (NIR) phosphorescence at room temperature is challenging to achieve for organic molecules due to negligible spin–orbit coupling and a low energy gap leading to fast non-radiative transitions. Here, we show a supramolecular host–guest strategy to harvest the energy from the low-lying triplet state of C64 nanographene tetraimide 1. 1H NMR and X-ray analysis confirmed the 1 : 2 stoichiometric binding of a Pt(II) porphyrin on the two π-surfaces of 1. While the free 1 does not show emission in the NIR, the host–guest complex solution shows NIR phosphorescence at 77 K. Further, between 860–1100 nm, room temperature NIR phosphorescence (λmax=900 nm, τavg=142 μs) was observed for a solid-state sample drop-casted from a preformed complex in solution. Theoretical calculations reveal a non-zero spin–orbit coupling between isoenergetic S1 and T3 of π-stacked [1 ⋅ Pt(II) porphyrin] complex. External heavy-atom-induced spin–orbit coupling along with rigidification and protection from oxygen in the solid-state promotes both the intersystem crossing from the first excited singlet state into the triplet manifold and the NIR phosphorescence from the lowest triplet state of 1.

  @article{Niyas_2024, abstract = {Near-Infrared (NIR) phosphorescence at room temperature is challenging to achieve for organic molecules due to negligible spin–orbit coupling and a low energy gap leading to fast non-radiative transitions. Here, we show a supramolecular host–guest strategy to harvest the energy from the low-lying triplet state of C64 nanographene tetraimide 1. 1H NMR and X-ray analysis confirmed the 1 : 2 stoichiometric binding of a Pt(II) porphyrin on the two π-surfaces of 1. While the free 1 does not show emission in the NIR, the host–guest complex solution shows NIR phosphorescence at 77 K. Further, between 860–1100 nm, room temperature NIR phosphorescence (λmax=900 nm, τavg=142 μs) was observed for a solid-state sample drop-casted from a preformed complex in solution. Theoretical calculations reveal a non-zero spin–orbit coupling between isoenergetic S1 and T3 of π-stacked [1 ⋅ Pt(II) porphyrin] complex. External heavy-atom-induced spin–orbit coupling along with rigidification and protection from oxygen in the solid-state promotes both the intersystem crossing from the first excited singlet state into the triplet manifold and the NIR phosphorescence from the lowest triplet state of 1.}, author = {Niyas, M. A. and Garain, Swadhin and Shoyama, Kazutaka and Würthner, Frank}, journal = {Angew. Chem. Int. Ed.}, keywords = {myown}, month = {06}, number = 33, publisher = {Wiley}, title = {Room‐Temperature Near‐Infrared Phosphorescence from C64 Nanographene Tetraimide by π‐Stacking Complexation with Platinum Porphyrin}, volume = 63, year = 2024 }

  %0 Journal Article %1 Niyas_2024 %A Niyas, M. A. %A Garain, Swadhin %A Shoyama, Kazutaka %A Würthner, Frank %D 2024 %I Wiley %J Angew. Chem. Int. Ed. %N 33 %R 10.1002/anie.202406353 %T Room‐Temperature Near‐Infrared Phosphorescence from C64 Nanographene Tetraimide by π‐Stacking Complexation with Platinum Porphyrin %U http://dx.doi.org/10.1002/anie.202406353 %V 63 %X Near-Infrared (NIR) phosphorescence at room temperature is challenging to achieve for organic molecules due to negligible spin–orbit coupling and a low energy gap leading to fast non-radiative transitions. Here, we show a supramolecular host–guest strategy to harvest the energy from the low-lying triplet state of C64 nanographene tetraimide 1. 1H NMR and X-ray analysis confirmed the 1 : 2 stoichiometric binding of a Pt(II) porphyrin on the two π-surfaces of 1. While the free 1 does not show emission in the NIR, the host–guest complex solution shows NIR phosphorescence at 77 K. Further, between 860–1100 nm, room temperature NIR phosphorescence (λmax=900 nm, τavg=142 μs) was observed for a solid-state sample drop-casted from a preformed complex in solution. Theoretical calculations reveal a non-zero spin–orbit coupling between isoenergetic S1 and T3 of π-stacked [1 ⋅ Pt(II) porphyrin] complex. External heavy-atom-induced spin–orbit coupling along with rigidification and protection from oxygen in the solid-state promotes both the intersystem crossing from the first excited singlet state into the triplet manifold and the NIR phosphorescence from the lowest triplet state of 1.
• Guest-Mediated Modulation of Photophysical Pathways in a Coronene Bisimide Cyclophane. Rühe, Jessica; Vinod, Kavya; Hoh, Hanna; Shoyama, Kazutaka; Hariharan, Mahesh; Würthner, Frank. In J. Am. Chem. Soc., 146(41), pp. 28222–28232. 2024.
  • [ Abstract ]
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  The properties and functions of chromophores utilized by nature are strongly affected by the environment formed by the protein structure in the cells surrounding them. This concept is transferred here to host–guest complexes with the encapsulated guests acting as an environmental stimulus. A new cyclophane host based on coronene bisimide is presented that can encapsulate a wide variety of planar guest molecules with binding constants up to (4.29 ± 0.32) × 1010 M–1 in chloroform. Depending on the properties of the chosen guest, the excited state deactivation of the coronene bisimide chromophore can be tuned by the formation of host–guest complexes toward fluorescence, exciplex formation, charge separation, room-temperature phosphorescence (RTP), or thermally activated delayed fluorescence (TADF). The photophysical processes were investigated by UV/vis absorption, emission, and femto- and nanosecond transient absorption spectroscopy. To enhance the TADF, two different strategies were used by employing suitable guests: the reduction of the singlet–triplet gap by exciplex formation and the external heavy atom effect. Altogether, by using supramolecular host–guest complexation, a versatile multimodal chromophore system is achieved with the coronene bisimide cyclophane.

  @article{R_he_2024, abstract = {The properties and functions of chromophores utilized by nature are strongly affected by the environment formed by the protein structure in the cells surrounding them. This concept is transferred here to host–guest complexes with the encapsulated guests acting as an environmental stimulus. A new cyclophane host based on coronene bisimide is presented that can encapsulate a wide variety of planar guest molecules with binding constants up to (4.29 ± 0.32) × 1010 M–1 in chloroform. Depending on the properties of the chosen guest, the excited state deactivation of the coronene bisimide chromophore can be tuned by the formation of host–guest complexes toward fluorescence, exciplex formation, charge separation, room-temperature phosphorescence (RTP), or thermally activated delayed fluorescence (TADF). The photophysical processes were investigated by UV/vis absorption, emission, and femto- and nanosecond transient absorption spectroscopy. To enhance the TADF, two different strategies were used by employing suitable guests: the reduction of the singlet–triplet gap by exciplex formation and the external heavy atom effect. Altogether, by using supramolecular host–guest complexation, a versatile multimodal chromophore system is achieved with the coronene bisimide cyclophane.}, author = {Rühe, Jessica and Vinod, Kavya and Hoh, Hanna and Shoyama, Kazutaka and Hariharan, Mahesh and Würthner, Frank}, journal = {J. Am. Chem. Soc.}, keywords = {myown}, month = {09}, number = 41, pages = {28222-28232}, publisher = {American Chemical Society (ACS)}, title = {Guest-Mediated Modulation of Photophysical Pathways in a Coronene Bisimide Cyclophane}, volume = 146, year = 2024 }

  %0 Journal Article %1 R_he_2024 %A Rühe, Jessica %A Vinod, Kavya %A Hoh, Hanna %A Shoyama, Kazutaka %A Hariharan, Mahesh %A Würthner, Frank %D 2024 %I American Chemical Society (ACS) %J J. Am. Chem. Soc. %N 41 %P 28222-28232 %R 10.1021/jacs.4c08479 %T Guest-Mediated Modulation of Photophysical Pathways in a Coronene Bisimide Cyclophane %U http://dx.doi.org/10.1021/jacs.4c08479 %V 146 %X The properties and functions of chromophores utilized by nature are strongly affected by the environment formed by the protein structure in the cells surrounding them. This concept is transferred here to host–guest complexes with the encapsulated guests acting as an environmental stimulus. A new cyclophane host based on coronene bisimide is presented that can encapsulate a wide variety of planar guest molecules with binding constants up to (4.29 ± 0.32) × 1010 M–1 in chloroform. Depending on the properties of the chosen guest, the excited state deactivation of the coronene bisimide chromophore can be tuned by the formation of host–guest complexes toward fluorescence, exciplex formation, charge separation, room-temperature phosphorescence (RTP), or thermally activated delayed fluorescence (TADF). The photophysical processes were investigated by UV/vis absorption, emission, and femto- and nanosecond transient absorption spectroscopy. To enhance the TADF, two different strategies were used by employing suitable guests: the reduction of the singlet–triplet gap by exciplex formation and the external heavy atom effect. Altogether, by using supramolecular host–guest complexation, a versatile multimodal chromophore system is achieved with the coronene bisimide cyclophane.
• Synthesis of a helical boron-doped PAH by post-functionalization of 3,9-diboraperylene. Mützel, Carina; Shoyama, Kazutaka; Krause, Ana-Maria; Würthner, Frank. In Org. Chem. Front., 11(10), pp. 2747–2755. 2024.
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  We present herein the post-functionalization of doubly boron-doped polycyclic aromatic hydrocarbons (PAHs) by various aryl substituents, namely the syntheses of a series of (2,8,)3,9-aryl-substituted 3,9-diboraperylenes via boron-substitution of (2,8-diaryl-)3,9-dihydroxy-3,9-diboraperylenes. These new boron-doped PAHs exhibit two reversible reductions with a remarkably facile first reduction between E = −1.04 and −1.13 V vs. Fc+/Fc. Friedel–Crafts cyclization of the 2-isopropenylnaphthyl-substituted derivative afforded a helical boron-doped polycyclic aromatic hydrocarbon that is endowed with a low LUMO level, high absorption coefficients and fluorescence (ΦF = 0.73), combined with a one-dimensional π–π stacking interaction in the solid state.

  @article{D4QO00421C, abstract = {We present herein the post-functionalization of doubly boron-doped polycyclic aromatic hydrocarbons (PAHs) by various aryl substituents, namely the syntheses of a series of (2,8,)3,9-aryl-substituted 3,9-diboraperylenes via boron-substitution of (2,8-diaryl-)3,9-dihydroxy-3,9-diboraperylenes. These new boron-doped PAHs exhibit two reversible reductions with a remarkably facile first reduction between E = −1.04 and −1.13 V vs. Fc+/Fc. Friedel–Crafts cyclization of the 2-isopropenylnaphthyl-substituted derivative afforded a helical boron-doped polycyclic aromatic hydrocarbon that is endowed with a low LUMO level, high absorption coefficients and fluorescence (ΦF = 0.73), combined with a one-dimensional π–π stacking interaction in the solid state.}, author = {Mützel, Carina and Shoyama, Kazutaka and Krause, Ana-Maria and Würthner, Frank}, journal = {Org. Chem. Front.}, keywords = {myown}, number = 10, pages = {2747-2755}, publisher = {The Royal Society of Chemistry}, title = {Synthesis of a helical boron-doped PAH by post-functionalization of 3{,}9-diboraperylene}, volume = 11, year = 2024 }

  %0 Journal Article %1 D4QO00421C %A Mützel, Carina %A Shoyama, Kazutaka %A Krause, Ana-Maria %A Würthner, Frank %D 2024 %I The Royal Society of Chemistry %J Org. Chem. Front. %N 10 %P 2747-2755 %R 10.1039/D4QO00421C %T Synthesis of a helical boron-doped PAH by post-functionalization of 3,9-diboraperylene %U http://dx.doi.org/10.1039/D4QO00421C %V 11 %X We present herein the post-functionalization of doubly boron-doped polycyclic aromatic hydrocarbons (PAHs) by various aryl substituents, namely the syntheses of a series of (2,8,)3,9-aryl-substituted 3,9-diboraperylenes via boron-substitution of (2,8-diaryl-)3,9-dihydroxy-3,9-diboraperylenes. These new boron-doped PAHs exhibit two reversible reductions with a remarkably facile first reduction between E = −1.04 and −1.13 V vs. Fc+/Fc. Friedel–Crafts cyclization of the 2-isopropenylnaphthyl-substituted derivative afforded a helical boron-doped polycyclic aromatic hydrocarbon that is endowed with a low LUMO level, high absorption coefficients and fluorescence (ΦF = 0.73), combined with a one-dimensional π–π stacking interaction in the solid state.
• Cooperative Binding and Chirogenesis in an Expanded Perylene Bisimide Cyclophane. Sukumaran, Divya P.; Shoyama, Kazutaka; Dubey, Rajeev K.; Würthner, Frank. In J. Am. Chem. Soc., 146(31), pp. 22077–22084. 2024.
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  The encapsulation of more than one guest molecule into a synthetic cavity is a highly desirable yet a highly challenging task to achieve for neutral supramolecular hosts in organic media. Herein, we report a neutral perylene bisimide cyclophane, which has a tailored chiral cavity with an interchromophoric distance of 11.2 Å, capable of binding two aromatic guests in a π-stacked fashion. Detailed host–guest binding studies with a series of aromatic guests revealed that the encapsulation of the second guest in this cyclophane is notably more favored than the first one. Accordingly, for the encapsulation of the coronene dimer, a cooperativity factor (α) as high as 485 was observed, which is remarkably high for neutral host–guest systems. Furthermore, a successful chirality transfer, from the chiral host to encapsulated coronenes, resulted in a chiral charge-transfer (CT) complex and the rare observation of circularly polarized emission originating from the CT state for a noncovalent donor–acceptor assembly in solution. The involvement of the CT state also afforded an enhancement in the luminescence dissymmetry factor (glum) value due to its relatively large magnetic transition dipole moment. The 1:2 binding pattern and chirality-transfer were unambiguously verified by single-crystal X-ray diffraction analysis of the host–guest superstructures.

  @article{Sukumaran_2024, abstract = {The encapsulation of more than one guest molecule into a synthetic cavity is a highly desirable yet a highly challenging task to achieve for neutral supramolecular hosts in organic media. Herein, we report a neutral perylene bisimide cyclophane, which has a tailored chiral cavity with an interchromophoric distance of 11.2 Å, capable of binding two aromatic guests in a π-stacked fashion. Detailed host–guest binding studies with a series of aromatic guests revealed that the encapsulation of the second guest in this cyclophane is notably more favored than the first one. Accordingly, for the encapsulation of the coronene dimer, a cooperativity factor (α) as high as 485 was observed, which is remarkably high for neutral host–guest systems. Furthermore, a successful chirality transfer, from the chiral host to encapsulated coronenes, resulted in a chiral charge-transfer (CT) complex and the rare observation of circularly polarized emission originating from the CT state for a noncovalent donor–acceptor assembly in solution. The involvement of the CT state also afforded an enhancement in the luminescence dissymmetry factor (glum) value due to its relatively large magnetic transition dipole moment. The 1:2 binding pattern and chirality-transfer were unambiguously verified by single-crystal X-ray diffraction analysis of the host–guest superstructures.}, author = {Sukumaran, Divya P. and Shoyama, Kazutaka and Dubey, Rajeev K. and Würthner, Frank}, journal = {J. Am. Chem. Soc.}, keywords = {myown}, month = {07}, number = 31, pages = {22077–22084}, publisher = {American Chemical Society (ACS)}, title = {Cooperative Binding and Chirogenesis in an Expanded Perylene Bisimide Cyclophane}, volume = 146, year = 2024 }

  %0 Journal Article %1 Sukumaran_2024 %A Sukumaran, Divya P. %A Shoyama, Kazutaka %A Dubey, Rajeev K. %A Würthner, Frank %D 2024 %I American Chemical Society (ACS) %J J. Am. Chem. Soc. %N 31 %P 22077–22084 %R 10.1021/jacs.4c08073 %T Cooperative Binding and Chirogenesis in an Expanded Perylene Bisimide Cyclophane %U http://dx.doi.org/10.1021/jacs.4c08073 %V 146 %X The encapsulation of more than one guest molecule into a synthetic cavity is a highly desirable yet a highly challenging task to achieve for neutral supramolecular hosts in organic media. Herein, we report a neutral perylene bisimide cyclophane, which has a tailored chiral cavity with an interchromophoric distance of 11.2 Å, capable of binding two aromatic guests in a π-stacked fashion. Detailed host–guest binding studies with a series of aromatic guests revealed that the encapsulation of the second guest in this cyclophane is notably more favored than the first one. Accordingly, for the encapsulation of the coronene dimer, a cooperativity factor (α) as high as 485 was observed, which is remarkably high for neutral host–guest systems. Furthermore, a successful chirality transfer, from the chiral host to encapsulated coronenes, resulted in a chiral charge-transfer (CT) complex and the rare observation of circularly polarized emission originating from the CT state for a noncovalent donor–acceptor assembly in solution. The involvement of the CT state also afforded an enhancement in the luminescence dissymmetry factor (glum) value due to its relatively large magnetic transition dipole moment. The 1:2 binding pattern and chirality-transfer were unambiguously verified by single-crystal X-ray diffraction analysis of the host–guest superstructures.
• High Sensitivity and Ultra‐Broad‐Range NH3 Sensor Arrays by Precise Control of Step Defects on The Surface of Cl2‐NDI Single Crystals. Lu, Bin; Stolte, Matthias; Liu, Dong; Zhang, Xiaojing; Zhao, Lihui; Tian, Liehao; Frisbie, C. Daniel; Würthner, Frank; Tao, Xutang; He, Tao. In Adv. Sci., 11(14). 2024.
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  Vapor sensors with both high sensitivity and broad detection range are technically challenging yet highly desirable for widespread chemical sensing applications in diverse environments. Generally, an increased surface-to-volume ratio can effectively enhance the sensitivity to low concentrations, but often with the trade-off of a constrained sensing range. Here, an approach is demonstrated for NH3 sensor arrays with an unprecedentedly broad sensing range by introducing controllable steps on the surface of an n-type single crystal. Step edges, serving as adsorption sites with electron-deficient properties, are well-defined, discrete, and electronically active. NH3 molecules selectively adsorb at the step edges and nearly eliminate known trap-like character, which is demonstrated by surface potential imaging. Consequently, the strategy can significantly boost the sensitivity of two-terminal NH3 resistance sensors on thin crystals with a few steps while simultaneously enhancing the tolerance on thick crystals with dense steps. Incorporation of these crystals into parallel sensor arrays results in ppb–to–% level detection range and a convenient linear relation between sheet conductance and semi-log NH3 concentration, allowing for the precise localization of vapor leakage. In general, the results suggest new opportunities for defect engineering of organic semiconductor crystal surfaces for purposeful vapor or chemical sensing.

  @article{Lu_2024, abstract = {Vapor sensors with both high sensitivity and broad detection range are technically challenging yet highly desirable for widespread chemical sensing applications in diverse environments. Generally, an increased surface-to-volume ratio can effectively enhance the sensitivity to low concentrations, but often with the trade-off of a constrained sensing range. Here, an approach is demonstrated for NH3 sensor arrays with an unprecedentedly broad sensing range by introducing controllable steps on the surface of an n-type single crystal. Step edges, serving as adsorption sites with electron-deficient properties, are well-defined, discrete, and electronically active. NH3 molecules selectively adsorb at the step edges and nearly eliminate known trap-like character, which is demonstrated by surface potential imaging. Consequently, the strategy can significantly boost the sensitivity of two-terminal NH3 resistance sensors on thin crystals with a few steps while simultaneously enhancing the tolerance on thick crystals with dense steps. Incorporation of these crystals into parallel sensor arrays results in ppb–to–% level detection range and a convenient linear relation between sheet conductance and semi-log NH3 concentration, allowing for the precise localization of vapor leakage. In general, the results suggest new opportunities for defect engineering of organic semiconductor crystal surfaces for purposeful vapor or chemical sensing.}, author = {Lu, Bin and Stolte, Matthias and Liu, Dong and Zhang, Xiaojing and Zhao, Lihui and Tian, Liehao and Frisbie, C. Daniel and Würthner, Frank and Tao, Xutang and He, Tao}, journal = {Adv. Sci.}, keywords = {myown}, month = {02}, number = 14, publisher = {Wiley}, title = {High Sensitivity and Ultra‐Broad‐Range NH3 Sensor Arrays by Precise Control of Step Defects on The Surface of Cl2‐NDI Single Crystals}, volume = 11, year = 2024 }

  %0 Journal Article %1 Lu_2024 %A Lu, Bin %A Stolte, Matthias %A Liu, Dong %A Zhang, Xiaojing %A Zhao, Lihui %A Tian, Liehao %A Frisbie, C. Daniel %A Würthner, Frank %A Tao, Xutang %A He, Tao %D 2024 %I Wiley %J Adv. Sci. %N 14 %R 10.1002/advs.202308036 %T High Sensitivity and Ultra‐Broad‐Range NH3 Sensor Arrays by Precise Control of Step Defects on The Surface of Cl2‐NDI Single Crystals %U http://dx.doi.org/10.1002/advs.202308036 %V 11 %X Vapor sensors with both high sensitivity and broad detection range are technically challenging yet highly desirable for widespread chemical sensing applications in diverse environments. Generally, an increased surface-to-volume ratio can effectively enhance the sensitivity to low concentrations, but often with the trade-off of a constrained sensing range. Here, an approach is demonstrated for NH3 sensor arrays with an unprecedentedly broad sensing range by introducing controllable steps on the surface of an n-type single crystal. Step edges, serving as adsorption sites with electron-deficient properties, are well-defined, discrete, and electronically active. NH3 molecules selectively adsorb at the step edges and nearly eliminate known trap-like character, which is demonstrated by surface potential imaging. Consequently, the strategy can significantly boost the sensitivity of two-terminal NH3 resistance sensors on thin crystals with a few steps while simultaneously enhancing the tolerance on thick crystals with dense steps. Incorporation of these crystals into parallel sensor arrays results in ppb–to–% level detection range and a convenient linear relation between sheet conductance and semi-log NH3 concentration, allowing for the precise localization of vapor leakage. In general, the results suggest new opportunities for defect engineering of organic semiconductor crystal surfaces for purposeful vapor or chemical sensing.
• The Delayed Box: Biphenyl Bisimide Cyclophane, a Supramolecular Nano-environment for the Efficient Generation of Delayed Fluorescence. Garain, Swadhin; Shoyama, Kazutaka; Ginder, Lea-Marleen; Sárosi, Menyhárt; Würthner, Frank. In J. Am. Chem. Soc., 146(31), pp. 22056–22063. 2024.
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  Activating delayed fluorescence emission in a dilute solution via a non-covalent approach is a formidable challenge. In this report, we propose a strategy for efficient delayed fluorescence generation in dilute solution using a non-covalent approach via supramolecularly engineered cyclophane-based nanoenvironments that provide sufficient binding strength to π-conjugated guests and that can stabilize triplet excitons by reducing vibrational dissipation and lowering the singlet–triplet energy gap for efficient delayed fluorescence emission. Toward this goal, a novel biphenyl bisimide-derived cyclophane is introduced as an electron-deficient and efficient triplet-generating host. Upon encapsulation of various carbazole-derived guests inside the nanocavity of this cyclophane, emissive charge transfer (CT) states close to the triplet energy level of the biphenyl bisimide are generated. The experimental results of host–guest studies manifest high association constants up to 104 M–1 as the prerequisite for inclusion complex formation, the generation of emissive CT states, and triplet-state stabilization in a diluted solution state. By means of different carbazole guest molecules, we could realize tunable delayed fluorescence emission in this carbazole-encapsulated biphenyl bisimide cyclophane in methylcyclohexane/carbon tetrachloride solutions with a quantum yield (QY) of up to 15.6%. Crystal structure analyses and solid-state photophysical studies validate the conclusions from our solution studies and provide insights into the delayed fluorescence emission mechanism.

  @article{Garain_2024, abstract = {Activating delayed fluorescence emission in a dilute solution via a non-covalent approach is a formidable challenge. In this report, we propose a strategy for efficient delayed fluorescence generation in dilute solution using a non-covalent approach via supramolecularly engineered cyclophane-based nanoenvironments that provide sufficient binding strength to π-conjugated guests and that can stabilize triplet excitons by reducing vibrational dissipation and lowering the singlet–triplet energy gap for efficient delayed fluorescence emission. Toward this goal, a novel biphenyl bisimide-derived cyclophane is introduced as an electron-deficient and efficient triplet-generating host. Upon encapsulation of various carbazole-derived guests inside the nanocavity of this cyclophane, emissive charge transfer (CT) states close to the triplet energy level of the biphenyl bisimide are generated. The experimental results of host–guest studies manifest high association constants up to 104 M–1 as the prerequisite for inclusion complex formation, the generation of emissive CT states, and triplet-state stabilization in a diluted solution state. By means of different carbazole guest molecules, we could realize tunable delayed fluorescence emission in this carbazole-encapsulated biphenyl bisimide cyclophane in methylcyclohexane/carbon tetrachloride solutions with a quantum yield (QY) of up to 15.6%. Crystal structure analyses and solid-state photophysical studies validate the conclusions from our solution studies and provide insights into the delayed fluorescence emission mechanism.}, author = {Garain, Swadhin and Shoyama, Kazutaka and Ginder, Lea-Marleen and Sárosi, Menyhárt and Würthner, Frank}, journal = {J. Am. Chem. Soc.}, keywords = {myown}, month = {07}, number = 31, pages = {22056–22063}, publisher = {American Chemical Society (ACS)}, title = {The Delayed Box: Biphenyl Bisimide Cyclophane, a Supramolecular Nano-environment for the Efficient Generation of Delayed Fluorescence}, volume = 146, year = 2024 }

  %0 Journal Article %1 Garain_2024 %A Garain, Swadhin %A Shoyama, Kazutaka %A Ginder, Lea-Marleen %A Sárosi, Menyhárt %A Würthner, Frank %D 2024 %I American Chemical Society (ACS) %J J. Am. Chem. Soc. %N 31 %P 22056–22063 %R 10.1021/jacs.4c07730 %T The Delayed Box: Biphenyl Bisimide Cyclophane, a Supramolecular Nano-environment for the Efficient Generation of Delayed Fluorescence %U http://dx.doi.org/10.1021/jacs.4c07730 %V 146 %X Activating delayed fluorescence emission in a dilute solution via a non-covalent approach is a formidable challenge. In this report, we propose a strategy for efficient delayed fluorescence generation in dilute solution using a non-covalent approach via supramolecularly engineered cyclophane-based nanoenvironments that provide sufficient binding strength to π-conjugated guests and that can stabilize triplet excitons by reducing vibrational dissipation and lowering the singlet–triplet energy gap for efficient delayed fluorescence emission. Toward this goal, a novel biphenyl bisimide-derived cyclophane is introduced as an electron-deficient and efficient triplet-generating host. Upon encapsulation of various carbazole-derived guests inside the nanocavity of this cyclophane, emissive charge transfer (CT) states close to the triplet energy level of the biphenyl bisimide are generated. The experimental results of host–guest studies manifest high association constants up to 104 M–1 as the prerequisite for inclusion complex formation, the generation of emissive CT states, and triplet-state stabilization in a diluted solution state. By means of different carbazole guest molecules, we could realize tunable delayed fluorescence emission in this carbazole-encapsulated biphenyl bisimide cyclophane in methylcyclohexane/carbon tetrachloride solutions with a quantum yield (QY) of up to 15.6%. Crystal structure analyses and solid-state photophysical studies validate the conclusions from our solution studies and provide insights into the delayed fluorescence emission mechanism.

• Single-Molecule Ultrafast Fluorescence-Detected Pump-Probe Microscopy. Fersch, Daniel; Maly, Pavel; Rühe, Jessica; Lisinetskii, Victor; Hensen, Matthias; Würthner, Frank; Brixner, Tobias. In The Journal of Physical Chemistry Letters, 14(21), pp. 4923–4932. 2023.
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  We introduce fluorescence-detected pump–probe microscopy by combining a wavelength-tunable ultrafast laser with a confocal scanning fluorescence microscope, enabling access to the femtosecond time scale on the micrometer spatial scale. In addition, we obtain spectral information from Fourier transformation over excitation pulse-pair time delays. We demonstrate this new approach on a model system of a terrylene bisimide (TBI) dye embedded in a PMMA matrix and acquire the linear excitation spectrum as well as time-dependent pump–probe spectra simultaneously. We then push the technique toward single TBI molecules and analyze the statistical distribution of their excitation spectra. Furthermore, we demonstrate the ultrafast transient evolution of several individual molecules, highlighting their different behavior in contrast to the ensemble due to their individual local environment. By correlating the linear and nonlinear spectra, we assess the effect of the molecular environment on the excited-state energy.

  @article{Fersch_2023, abstract = {We introduce fluorescence-detected pump–probe microscopy by combining a wavelength-tunable ultrafast laser with a confocal scanning fluorescence microscope, enabling access to the femtosecond time scale on the micrometer spatial scale. In addition, we obtain spectral information from Fourier transformation over excitation pulse-pair time delays. We demonstrate this new approach on a model system of a terrylene bisimide (TBI) dye embedded in a PMMA matrix and acquire the linear excitation spectrum as well as time-dependent pump–probe spectra simultaneously. We then push the technique toward single TBI molecules and analyze the statistical distribution of their excitation spectra. Furthermore, we demonstrate the ultrafast transient evolution of several individual molecules, highlighting their different behavior in contrast to the ensemble due to their individual local environment. By correlating the linear and nonlinear spectra, we assess the effect of the molecular environment on the excited-state energy.}, author = {Fersch, Daniel and Maly, Pavel and Rühe, Jessica and Lisinetskii, Victor and Hensen, Matthias and Würthner, Frank and Brixner, Tobias}, journal = {The Journal of Physical Chemistry Letters}, keywords = {myown}, month = {05}, number = 21, pages = {4923–4932}, publisher = {American Chemical Society (ACS)}, title = {Single-Molecule Ultrafast Fluorescence-Detected Pump-Probe Microscopy}, volume = 14, year = 2023 }

  %0 Journal Article %1 Fersch_2023 %A Fersch, Daniel %A Maly, Pavel %A Rühe, Jessica %A Lisinetskii, Victor %A Hensen, Matthias %A Würthner, Frank %A Brixner, Tobias %D 2023 %I American Chemical Society (ACS) %J The Journal of Physical Chemistry Letters %N 21 %P 4923--4932 %R 10.1021/acs.jpclett.3c00839 %T Single-Molecule Ultrafast Fluorescence-Detected Pump-Probe Microscopy %U https://doi.org/10.1021%2Facs.jpclett.3c00839 %V 14 %X We introduce fluorescence-detected pump–probe microscopy by combining a wavelength-tunable ultrafast laser with a confocal scanning fluorescence microscope, enabling access to the femtosecond time scale on the micrometer spatial scale. In addition, we obtain spectral information from Fourier transformation over excitation pulse-pair time delays. We demonstrate this new approach on a model system of a terrylene bisimide (TBI) dye embedded in a PMMA matrix and acquire the linear excitation spectrum as well as time-dependent pump–probe spectra simultaneously. We then push the technique toward single TBI molecules and analyze the statistical distribution of their excitation spectra. Furthermore, we demonstrate the ultrafast transient evolution of several individual molecules, highlighting their different behavior in contrast to the ensemble due to their individual local environment. By correlating the linear and nonlinear spectra, we assess the effect of the molecular environment on the excited-state energy.
• Concentration-, Temperature- and Solvent-Dependent Self-Assembly: Merocyanine Dimerization as a Showcase Example for Obtaining Reliable Thermodynamic Data. Vonhausen, Yvonne; Würthner, Frank. In Chemistry - A European Journal, 29(37). 2023.
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  Mathematical models for the concentration-, temperature- and solvent-dependent analysis of self-assembly equilibria are derived for the most simple case of dimer formation, to highlight the assumptions these models and the thus determined thermodynamic parameters are based on. The three models were applied to UV/Vis absorption data for the dimerization of a highly dipolar merocyanine dye in 1,4-dioxane. Isothermal titration calorimetry (ITC) dilution experiments were performed as an independent reference technique. While the concentration-dependent analysis is according to our studies the most reliable method, also the less time-consuming temperature-dependent evaluation can give accurate results in the present example, despite small thermochromic effects. In contrast, the strong negative solvatochromism of the merocyanine tampers with the results from the solvent-dependent evaluation. Even though the studies presented in this work are limited to the monomer-dimer equilibrium of a dipolar dye, the basic principles can be transferred to other chromophores and different self-assembly models, including those for supramolecular polymerization.

  @article{Vonhausen_2023, abstract = {Mathematical models for the concentration-, temperature- and solvent-dependent analysis of self-assembly equilibria are derived for the most simple case of dimer formation, to highlight the assumptions these models and the thus determined thermodynamic parameters are based on. The three models were applied to UV/Vis absorption data for the dimerization of a highly dipolar merocyanine dye in 1,4-dioxane. Isothermal titration calorimetry (ITC) dilution experiments were performed as an independent reference technique. While the concentration-dependent analysis is according to our studies the most reliable method, also the less time-consuming temperature-dependent evaluation can give accurate results in the present example, despite small thermochromic effects. In contrast, the strong negative solvatochromism of the merocyanine tampers with the results from the solvent-dependent evaluation. Even though the studies presented in this work are limited to the monomer-dimer equilibrium of a dipolar dye, the basic principles can be transferred to other chromophores and different self-assembly models, including those for supramolecular polymerization.}, author = {Vonhausen, Yvonne and Würthner, Frank}, journal = {Chemistry - A European Journal}, keywords = {myown}, month = {05}, number = 37, publisher = {Wiley}, title = {Concentration-, Temperature- and Solvent-Dependent Self-Assembly: Merocyanine Dimerization as a Showcase Example for Obtaining Reliable Thermodynamic Data}, volume = 29, year = 2023 }

  %0 Journal Article %1 Vonhausen_2023 %A Vonhausen, Yvonne %A Würthner, Frank %D 2023 %I Wiley %J Chemistry - A European Journal %N 37 %R 10.1002/chem.202300359 %T Concentration-, Temperature- and Solvent-Dependent Self-Assembly: Merocyanine Dimerization as a Showcase Example for Obtaining Reliable Thermodynamic Data %U https://doi.org/10.1002%2Fchem.202300359 %V 29 %X Mathematical models for the concentration-, temperature- and solvent-dependent analysis of self-assembly equilibria are derived for the most simple case of dimer formation, to highlight the assumptions these models and the thus determined thermodynamic parameters are based on. The three models were applied to UV/Vis absorption data for the dimerization of a highly dipolar merocyanine dye in 1,4-dioxane. Isothermal titration calorimetry (ITC) dilution experiments were performed as an independent reference technique. While the concentration-dependent analysis is according to our studies the most reliable method, also the less time-consuming temperature-dependent evaluation can give accurate results in the present example, despite small thermochromic effects. In contrast, the strong negative solvatochromism of the merocyanine tampers with the results from the solvent-dependent evaluation. Even though the studies presented in this work are limited to the monomer-dimer equilibrium of a dipolar dye, the basic principles can be transferred to other chromophores and different self-assembly models, including those for supramolecular polymerization.
• Chiroptical Properties of Planar Benzobisthiazole-Bridged Squaraine Dimers. Freytag, Emely; Kreimendahl, Lasse; Holzapfel, Marco; Petersen, Jens; Lackinger, Heiko; Stolte, Matthias; Würthner, Frank; Mitric, Roland; Lambert, Christoph. In J. Org. Chem., 88(15), pp. 10777–10788. 2023.
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  Five chiral squaraine dimers were synthesized by fusing chiral indolenine semisquaraines with three different benzobisthiazole bridges. The thereby created squaraine dimers show a strong splitting of the lowest energy absorption bands caused by exciton coupling. The intensities of the two exciton transitions and the energetic splitting depend on the angle of the two squaraine moieties within the chromophore dimer. The electric circular dichroism spectra of the dimers show intense Cotton effects whose sign depends on the used squaraine chromophores. Sizable anisotropies gabs of up to 2.6 × 10–3 could be obtained. TD-DFT calculations were used to partition the rotational strength into the three Rosenfeld terms where the electric-magnetic coupling turned out to be the dominant contribution while the exciton chirality term is much smaller. This is because the chromophore dimers are essentially planar but the angle between the electric transition dipole moment of one squaraine and the magnetic transition dipole moment of the other squaraine strongly deviates from 90°, which makes the dot product between the two moment vectors and, thus, the rotational strength substantial.

  @article{Freytag_2023, abstract = {Five chiral squaraine dimers were synthesized by fusing chiral indolenine semisquaraines with three different benzobisthiazole bridges. The thereby created squaraine dimers show a strong splitting of the lowest energy absorption bands caused by exciton coupling. The intensities of the two exciton transitions and the energetic splitting depend on the angle of the two squaraine moieties within the chromophore dimer. The electric circular dichroism spectra of the dimers show intense Cotton effects whose sign depends on the used squaraine chromophores. Sizable anisotropies gabs of up to 2.6 × 10–3 could be obtained. TD-DFT calculations were used to partition the rotational strength into the three Rosenfeld terms where the electric-magnetic coupling turned out to be the dominant contribution while the exciton chirality term is much smaller. This is because the chromophore dimers are essentially planar but the angle between the electric transition dipole moment of one squaraine and the magnetic transition dipole moment of the other squaraine strongly deviates from 90°, which makes the dot product between the two moment vectors and, thus, the rotational strength substantial.}, author = {Freytag, Emely and Kreimendahl, Lasse and Holzapfel, Marco and Petersen, Jens and Lackinger, Heiko and Stolte, Matthias and Würthner, Frank and Mitric, Roland and Lambert, Christoph}, journal = {J. Org. Chem.}, keywords = {myown}, month = {07}, number = 15, pages = {10777–10788}, title = {Chiroptical Properties of Planar Benzobisthiazole-Bridged Squaraine Dimers}, volume = 88, year = 2023 }

  %0 Journal Article %1 Freytag_2023 %A Freytag, Emely %A Kreimendahl, Lasse %A Holzapfel, Marco %A Petersen, Jens %A Lackinger, Heiko %A Stolte, Matthias %A Würthner, Frank %A Mitric, Roland %A Lambert, Christoph %D 2023 %J J. Org. Chem. %N 15 %P 10777--10788 %R 10.1021/acs.joc.3c00821 %T Chiroptical Properties of Planar Benzobisthiazole-Bridged Squaraine Dimers %U https://doi.org/10.1021%2Facs.joc.3c00821 %V 88 %X Five chiral squaraine dimers were synthesized by fusing chiral indolenine semisquaraines with three different benzobisthiazole bridges. The thereby created squaraine dimers show a strong splitting of the lowest energy absorption bands caused by exciton coupling. The intensities of the two exciton transitions and the energetic splitting depend on the angle of the two squaraine moieties within the chromophore dimer. The electric circular dichroism spectra of the dimers show intense Cotton effects whose sign depends on the used squaraine chromophores. Sizable anisotropies gabs of up to 2.6 × 10–3 could be obtained. TD-DFT calculations were used to partition the rotational strength into the three Rosenfeld terms where the electric-magnetic coupling turned out to be the dominant contribution while the exciton chirality term is much smaller. This is because the chromophore dimers are essentially planar but the angle between the electric transition dipole moment of one squaraine and the magnetic transition dipole moment of the other squaraine strongly deviates from 90°, which makes the dot product between the two moment vectors and, thus, the rotational strength substantial.
• Preferential molecular recognition of heterochiral guests within a cyclophane receptor. Weh, Manuel; Shoyama, Kazutaka; Würthner, Frank. In Nature Communications, 14(1). 2023.
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  The discrimination of enantiomers by natural receptors is a well-established phenomenon. In contrast the number of synthetic receptors with the capability for enantioselective molecular recognition of chiral substrates is scarce and for chiral cyclophanes indicative for a preferential binding of homochiral guests. Here we introduce a cyclophane composed of two homochiral core-twisted perylene bisimide (PBI) units connected by p-xylylene spacers and demonstrate its preference for the complexation of [5]helicene of opposite helicity compared to the PBI units of the host. The pronounced enantio-differentiation of this molecular receptor for heterochiral guests can be utilized for the enrichment of the P-PBI-M-helicene-P-PBI epimeric bimolecular complex. Our experimental results are supported by DFT calculations, which reveal that the sterically demanding bay substituents attached to the PBI chromophores disturb the helical shape match of the perylene core and homochiral substrates and thereby enforce the formation of syndiotactic host-guest complex structures. Hence, the most efficient substrate binding is observed for those aromatic guests, e. g. perylene, [4]helicene, phenanthrene and biphenyl, that can easily adapt in non-planar axially chiral conformations due to their inherent conformational flexibility. In all cases the induced chirality for the guest is opposed to those of the embedding PBI units, leading to heterochiral host-guest structures.

  @article{Weh_2023, abstract = {The discrimination of enantiomers by natural receptors is a well-established phenomenon. In contrast the number of synthetic receptors with the capability for enantioselective molecular recognition of chiral substrates is scarce and for chiral cyclophanes indicative for a preferential binding of homochiral guests. Here we introduce a cyclophane composed of two homochiral core-twisted perylene bisimide (PBI) units connected by p-xylylene spacers and demonstrate its preference for the complexation of [5]helicene of opposite helicity compared to the PBI units of the host. The pronounced enantio-differentiation of this molecular receptor for heterochiral guests can be utilized for the enrichment of the P-PBI-M-helicene-P-PBI epimeric bimolecular complex. Our experimental results are supported by DFT calculations, which reveal that the sterically demanding bay substituents attached to the PBI chromophores disturb the helical shape match of the perylene core and homochiral substrates and thereby enforce the formation of syndiotactic host-guest complex structures. Hence, the most efficient substrate binding is observed for those aromatic guests, e. g. perylene, [4]helicene, phenanthrene and biphenyl, that can easily adapt in non-planar axially chiral conformations due to their inherent conformational flexibility. In all cases the induced chirality for the guest is opposed to those of the embedding PBI units, leading to heterochiral host-guest structures.}, author = {Weh, Manuel and Shoyama, Kazutaka and Würthner, Frank}, journal = {Nature Communications}, keywords = {myown}, month = {01}, number = 1, publisher = {Springer Science and Business Media {LLC}}, title = {Preferential molecular recognition of heterochiral guests within a cyclophane receptor}, volume = 14, year = 2023 }

  %0 Journal Article %1 Weh_2023 %A Weh, Manuel %A Shoyama, Kazutaka %A Würthner, Frank %D 2023 %I Springer Science and Business Media LLC %J Nature Communications %N 1 %R 10.1038/s41467-023-35851-3 %T Preferential molecular recognition of heterochiral guests within a cyclophane receptor %U https://doi.org/10.1038%2Fs41467-023-35851-3 %V 14 %X The discrimination of enantiomers by natural receptors is a well-established phenomenon. In contrast the number of synthetic receptors with the capability for enantioselective molecular recognition of chiral substrates is scarce and for chiral cyclophanes indicative for a preferential binding of homochiral guests. Here we introduce a cyclophane composed of two homochiral core-twisted perylene bisimide (PBI) units connected by p-xylylene spacers and demonstrate its preference for the complexation of [5]helicene of opposite helicity compared to the PBI units of the host. The pronounced enantio-differentiation of this molecular receptor for heterochiral guests can be utilized for the enrichment of the P-PBI-M-helicene-P-PBI epimeric bimolecular complex. Our experimental results are supported by DFT calculations, which reveal that the sterically demanding bay substituents attached to the PBI chromophores disturb the helical shape match of the perylene core and homochiral substrates and thereby enforce the formation of syndiotactic host-guest complex structures. Hence, the most efficient substrate binding is observed for those aromatic guests, e. g. perylene, [4]helicene, phenanthrene and biphenyl, that can easily adapt in non-planar axially chiral conformations due to their inherent conformational flexibility. In all cases the induced chirality for the guest is opposed to those of the embedding PBI units, leading to heterochiral host-guest structures.
• Folding-Induced Promotion of Proton-Coupled Electron Transfers via Proximal Base for Light-Driven Water Oxidation. Noll, Niklas; Groß, Tobias; Shoyama, Kazutaka; Beuerle, Florian; Würthner, Frank. In Angew. Chem. Int. Ed., 62(7). 2023.
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  Proton-coupled electron-transfer (PCET) processes play a key role in biocatalytic energy conversion and storage, for example, photosynthesis or nitrogen fixation. Here, we report a series of bipyridine-containing di- to tetranuclear Ru(bda) macrocycles 2 C–4 C (bda: 2,2′-bipyridine-6,6′-dicarboxylate) to promote O−O bond formation. In photocatalytic water oxidation under neutral conditions, all complexes 2 C–4 C prevail in a folded conformation that support the water nucleophilic attack (WNA) pathway with remarkable turnover frequencies of up to 15.5 s−1 per Ru unit respectively. Single-crystal X-ray analysis revealed an increased tendency for intramolecular π-π stacking and preorganization of the proximal bases close to the active centers for the larger macrocycles. H/D kinetic isotope effect studies and electrochemical data demonstrate the key role of the proximal bipyridines as proton acceptors in lowering the activation barrier for the crucial nucleophilic attack of H2O in the WNA mechanism.

  @article{Noll_2023, abstract = {Proton-coupled electron-transfer (PCET) processes play a key role in biocatalytic energy conversion and storage, for example, photosynthesis or nitrogen fixation. Here, we report a series of bipyridine-containing di- to tetranuclear Ru(bda) macrocycles 2 C–4 C (bda: 2,2′-bipyridine-6,6′-dicarboxylate) to promote O−O bond formation. In photocatalytic water oxidation under neutral conditions, all complexes 2 C–4 C prevail in a folded conformation that support the water nucleophilic attack (WNA) pathway with remarkable turnover frequencies of up to 15.5 s−1 per Ru unit respectively. Single-crystal X-ray analysis revealed an increased tendency for intramolecular π-π stacking and preorganization of the proximal bases close to the active centers for the larger macrocycles. H/D kinetic isotope effect studies and electrochemical data demonstrate the key role of the proximal bipyridines as proton acceptors in lowering the activation barrier for the crucial nucleophilic attack of H2O in the WNA mechanism.}, author = {Noll, Niklas and Groß, Tobias and Shoyama, Kazutaka and Beuerle, Florian and Würthner, Frank}, journal = {Angew. Chem. Int. Ed.}, keywords = {myown}, month = {01}, number = 7, publisher = {Wiley}, title = {Folding-Induced Promotion of Proton-Coupled Electron Transfers via Proximal Base for Light-Driven Water Oxidation}, volume = 62, year = 2023 }

  %0 Journal Article %1 Noll_2023 %A Noll, Niklas %A Groß, Tobias %A Shoyama, Kazutaka %A Beuerle, Florian %A Würthner, Frank %D 2023 %I Wiley %J Angew. Chem. Int. Ed. %N 7 %R 10.1002/anie.202217745 %T Folding-Induced Promotion of Proton-Coupled Electron Transfers via Proximal Base for Light-Driven Water Oxidation %U https://doi.org/10.1002%2Fanie.202217745 %V 62 %X Proton-coupled electron-transfer (PCET) processes play a key role in biocatalytic energy conversion and storage, for example, photosynthesis or nitrogen fixation. Here, we report a series of bipyridine-containing di- to tetranuclear Ru(bda) macrocycles 2 C–4 C (bda: 2,2′-bipyridine-6,6′-dicarboxylate) to promote O−O bond formation. In photocatalytic water oxidation under neutral conditions, all complexes 2 C–4 C prevail in a folded conformation that support the water nucleophilic attack (WNA) pathway with remarkable turnover frequencies of up to 15.5 s−1 per Ru unit respectively. Single-crystal X-ray analysis revealed an increased tendency for intramolecular π-π stacking and preorganization of the proximal bases close to the active centers for the larger macrocycles. H/D kinetic isotope effect studies and electrochemical data demonstrate the key role of the proximal bipyridines as proton acceptors in lowering the activation barrier for the crucial nucleophilic attack of H2O in the WNA mechanism.
• Enantiopure J-Aggregate of Quaterrylene Bisimides for Strong Chiroptical NIR-Response. Mahlmeister, Bernhard; Schembri, Tim; Stepanenko, Vladimir; Shoyama, Kazutaka; Stolte, Matthias; Würthner, Frank. In J. Am. Chem. Soc., 145(24), pp. 13302–13311. 2023.
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  Chiral polycyclic aromatic hydrocarbons can be tailored for next-generation photonic materials by carefully designing their molecular as well as supramolecular architectures. Hence, excitonic coupling can boost the chiroptical response in extended aggregates but is still challenging to achieve by pure self-assembly. Whereas most reports on these potential materials cover the UV and visible spectral range, systems in the near infrared (NIR) are underdeveloped. We report a new quaterrylene bisimide derivative with a conformationally stable twisted π-backbone enabled by the sterical congestion of a fourfold bay-arylation. Rendering the π-subplanes accessible by small imide substituents allows for a slip-stacked chiral arrangement by kinetic self-assembly in low polarity solvents. The well dispersed solid-state aggregate reveals a sharp optical signature of strong J-type excitonic coupling in both absorption (897 nm) and emission (912 nm) far in the NIR region and reaches absorption dissymmetry factors up to 1.1 × 10–2. The structural elucidation was achieved by atomic force microscopy and single-crystal X-ray analysis which we combined to derive a structural model of a fourfold stranded enantiopure superhelix. We could deduce that the role of phenyl substituents is not only granting stable axial chirality but also guiding the chromophore into a chiral supramolecular arrangement needed for strong excitonic chirality.

  @article{Mahlmeister_2023, abstract = {Chiral polycyclic aromatic hydrocarbons can be tailored for next-generation photonic materials by carefully designing their molecular as well as supramolecular architectures. Hence, excitonic coupling can boost the chiroptical response in extended aggregates but is still challenging to achieve by pure self-assembly. Whereas most reports on these potential materials cover the UV and visible spectral range, systems in the near infrared (NIR) are underdeveloped. We report a new quaterrylene bisimide derivative with a conformationally stable twisted π-backbone enabled by the sterical congestion of a fourfold bay-arylation. Rendering the π-subplanes accessible by small imide substituents allows for a slip-stacked chiral arrangement by kinetic self-assembly in low polarity solvents. The well dispersed solid-state aggregate reveals a sharp optical signature of strong J-type excitonic coupling in both absorption (897 nm) and emission (912 nm) far in the NIR region and reaches absorption dissymmetry factors up to 1.1 × 10–2. The structural elucidation was achieved by atomic force microscopy and single-crystal X-ray analysis which we combined to derive a structural model of a fourfold stranded enantiopure superhelix. We could deduce that the role of phenyl substituents is not only granting stable axial chirality but also guiding the chromophore into a chiral supramolecular arrangement needed for strong excitonic chirality.}, author = {Mahlmeister, Bernhard and Schembri, Tim and Stepanenko, Vladimir and Shoyama, Kazutaka and Stolte, Matthias and Würthner, Frank}, journal = {J. Am. Chem. Soc.}, keywords = {myown}, month = {06}, number = 24, pages = {13302–13311}, publisher = {American Chemical Society (ACS)}, title = {Enantiopure J-Aggregate of Quaterrylene Bisimides for Strong Chiroptical NIR-Response}, volume = 145, year = 2023 }

  %0 Journal Article %1 Mahlmeister_2023 %A Mahlmeister, Bernhard %A Schembri, Tim %A Stepanenko, Vladimir %A Shoyama, Kazutaka %A Stolte, Matthias %A Würthner, Frank %D 2023 %I American Chemical Society (ACS) %J J. Am. Chem. Soc. %N 24 %P 13302--13311 %R 10.1021/jacs.3c03367 %T Enantiopure J-Aggregate of Quaterrylene Bisimides for Strong Chiroptical NIR-Response %U https://doi.org/10.1021%2Fjacs.3c03367 %V 145 %X Chiral polycyclic aromatic hydrocarbons can be tailored for next-generation photonic materials by carefully designing their molecular as well as supramolecular architectures. Hence, excitonic coupling can boost the chiroptical response in extended aggregates but is still challenging to achieve by pure self-assembly. Whereas most reports on these potential materials cover the UV and visible spectral range, systems in the near infrared (NIR) are underdeveloped. We report a new quaterrylene bisimide derivative with a conformationally stable twisted π-backbone enabled by the sterical congestion of a fourfold bay-arylation. Rendering the π-subplanes accessible by small imide substituents allows for a slip-stacked chiral arrangement by kinetic self-assembly in low polarity solvents. The well dispersed solid-state aggregate reveals a sharp optical signature of strong J-type excitonic coupling in both absorption (897 nm) and emission (912 nm) far in the NIR region and reaches absorption dissymmetry factors up to 1.1 × 10–2. The structural elucidation was achieved by atomic force microscopy and single-crystal X-ray analysis which we combined to derive a structural model of a fourfold stranded enantiopure superhelix. We could deduce that the role of phenyl substituents is not only granting stable axial chirality but also guiding the chromophore into a chiral supramolecular arrangement needed for strong excitonic chirality.
• Playing Lego with perylene dyes. Dubey, Rajeev K.; Würthner, Frank. In Nat. Chem., 15(6), pp. 884–884. 2023.
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  @article{Dubey_2023, author = {Dubey, Rajeev K. and Würthner, Frank}, journal = {Nat. Chem.}, keywords = {myown}, month = {06}, number = 6, pages = {884–884}, publisher = {Springer Science and Business Media LLC}, title = {Playing Lego with perylene dyes}, volume = 15, year = 2023 }

  %0 Journal Article %1 Dubey_2023 %A Dubey, Rajeev K. %A Würthner, Frank %D 2023 %I Springer Science and Business Media LLC %J Nat. Chem. %N 6 %P 884--884 %R 10.1038/s41557-023-01202-4 %T Playing Lego with perylene dyes %U https://doi.org/10.1038%2Fs41557-023-01202-4 %V 15
• Water-Soluble Cationic Perylene Diimide Dyes as Stable Photocatalysts for H2O2 Evolution. Gryszel, Maciej; Schlossarek, Tim; Würthner, Frank; Natali, Mirco; Glowacki, Eric Daniel. In ChemPhotoChem, 7(9). 2023.
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  Photocatalytic generation of hydrogen peroxide, H2O2, has gained increasing attention in recent years, with applications ranging from solar energy conversion to biophysical research. While semiconducting solid-state materials are normally regarded as the workhorse for photogeneration of H2O2, an intriguing alternative for on-demand H2O2 is the use of photocatalytic organic dyes. Herein we report the use of water-soluble dyes based on perylene diimide molecules which behave as true molecular catalysts for the light-induced conversion of dissolved oxygen to hydrogen peroxide. In particular, we address how to obtain visible-light photocatalysts which are stable with respect to aggregation and photochemical degradation. We report on the factors affecting efficiency and stability, including variable electron donors, oxygen partial pressure, pH, and molecular catalyst structure. The result is a perylene diimide derivative with unprecedented peroxide evolution performance using a broad range of organic donor molecules and operating in a wide pH range.

  @article{Gryszel_2023, abstract = {Photocatalytic generation of hydrogen peroxide, H2O2, has gained increasing attention in recent years, with applications ranging from solar energy conversion to biophysical research. While semiconducting solid-state materials are normally regarded as the workhorse for photogeneration of H2O2, an intriguing alternative for on-demand H2O2 is the use of photocatalytic organic dyes. Herein we report the use of water-soluble dyes based on perylene diimide molecules which behave as true molecular catalysts for the light-induced conversion of dissolved oxygen to hydrogen peroxide. In particular, we address how to obtain visible-light photocatalysts which are stable with respect to aggregation and photochemical degradation. We report on the factors affecting efficiency and stability, including variable electron donors, oxygen partial pressure, pH, and molecular catalyst structure. The result is a perylene diimide derivative with unprecedented peroxide evolution performance using a broad range of organic donor molecules and operating in a wide pH range.}, author = {Gryszel, Maciej and Schlossarek, Tim and Würthner, Frank and Natali, Mirco and Glowacki, Eric Daniel}, journal = {ChemPhotoChem}, keywords = {myown}, month = {06}, number = 9, publisher = {Wiley}, title = {Water-Soluble Cationic Perylene Diimide Dyes as Stable Photocatalysts for H2O2 Evolution}, volume = 7, year = 2023 }

  %0 Journal Article %1 Gryszel_2023 %A Gryszel, Maciej %A Schlossarek, Tim %A Würthner, Frank %A Natali, Mirco %A Glowacki, Eric Daniel %D 2023 %I Wiley %J ChemPhotoChem %N 9 %R 10.1002/cptc.202300070 %T Water-Soluble Cationic Perylene Diimide Dyes as Stable Photocatalysts for H2O2 Evolution %U https://doi.org/10.1002%2Fcptc.202300070 %V 7 %X Photocatalytic generation of hydrogen peroxide, H2O2, has gained increasing attention in recent years, with applications ranging from solar energy conversion to biophysical research. While semiconducting solid-state materials are normally regarded as the workhorse for photogeneration of H2O2, an intriguing alternative for on-demand H2O2 is the use of photocatalytic organic dyes. Herein we report the use of water-soluble dyes based on perylene diimide molecules which behave as true molecular catalysts for the light-induced conversion of dissolved oxygen to hydrogen peroxide. In particular, we address how to obtain visible-light photocatalysts which are stable with respect to aggregation and photochemical degradation. We report on the factors affecting efficiency and stability, including variable electron donors, oxygen partial pressure, pH, and molecular catalyst structure. The result is a perylene diimide derivative with unprecedented peroxide evolution performance using a broad range of organic donor molecules and operating in a wide pH range.
• Naphthalimide-Fused Subphthalocyanines: Electron-Deficient Materials Prepared by Cascade Annulation. Labella, Jorge; Shoyama, Kazutaka; Guzman, David; Schembri, Tim; Stolte, Matthias; Torres, Tomas; Würthner, Frank. In ACS Materials Letters, pp. 543–548. 2023.
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  Imide-fused porphyrinoids are becoming key components in the area of molecular materials. Herein we report the synthesis of naphthalimide (NMI)-annulated subphthalocyanines (SubPcs) designed as an NIR-absorbing n-type organic semiconductor. Two different synthetic pathways could be applied for the preparation of NMI-fused SubPcs. The first consists of a [3 + 2] annulation between SubPc boronic ester and dibromo-NMI. This annulation, which involves the first CH activation reaction of a SubPc derivative reported so far, is totally regioselective to the β-position. Density functional theory (DFT) indicated that such position is favored both kinetically and thermodynamically. On the other hand, the second method relies on a cyclotrimerization of NMI-fused phthalonitrile. Electrochemical measurements and DFT calculations revealed that these NMI-fused SubPcs have low-lying LUMO energy levels suitable for electron charge transport. The N-alkyl substituted derivative (NMI-SubPc 2) was successfully applied as an nonfullerene acceptor (NFA) in combination with donor polymer PM6 in bulk-heterojunction (BHJ) organic solar cells (OSCs) with a highest power conversion efficiency (PCE) of 7.0%. This value is comparable to the record PCE of SubPc derivatives in BHJ-OSCs. Our results open a new vista in the preparation of π-extended contracted porphyrinoids and substantiate the potential of this new class of strong-absorbing electron-acceptor materials for applications in optoelectronic devices.

  @article{Labella_2023, abstract = {Imide-fused porphyrinoids are becoming key components in the area of molecular materials. Herein we report the synthesis of naphthalimide (NMI)-annulated subphthalocyanines (SubPcs) designed as an NIR-absorbing n-type organic semiconductor. Two different synthetic pathways could be applied for the preparation of NMI-fused SubPcs. The first consists of a [3 + 2] annulation between SubPc boronic ester and dibromo-NMI. This annulation, which involves the first CH activation reaction of a SubPc derivative reported so far, is totally regioselective to the β-position. Density functional theory (DFT) indicated that such position is favored both kinetically and thermodynamically. On the other hand, the second method relies on a cyclotrimerization of NMI-fused phthalonitrile. Electrochemical measurements and DFT calculations revealed that these NMI-fused SubPcs have low-lying LUMO energy levels suitable for electron charge transport. The N-alkyl substituted derivative (NMI-SubPc 2) was successfully applied as an nonfullerene acceptor (NFA) in combination with donor polymer PM6 in bulk-heterojunction (BHJ) organic solar cells (OSCs) with a highest power conversion efficiency (PCE) of 7.0%. This value is comparable to the record PCE of SubPc derivatives in BHJ-OSCs. Our results open a new vista in the preparation of π-extended contracted porphyrinoids and substantiate the potential of this new class of strong-absorbing electron-acceptor materials for applications in optoelectronic devices.}, author = {Labella, Jorge and Shoyama, Kazutaka and Guzman, David and Schembri, Tim and Stolte, Matthias and Torres, Tomas and Würthner, Frank}, journal = {ACS Materials Letters}, keywords = {myown}, month = {01}, pages = {543–548}, publisher = {American Chemical Society ({ACS})}, title = {Naphthalimide-Fused Subphthalocyanines: Electron-Deficient Materials Prepared by Cascade Annulation}, year = 2023 }

  %0 Journal Article %1 Labella_2023 %A Labella, Jorge %A Shoyama, Kazutaka %A Guzman, David %A Schembri, Tim %A Stolte, Matthias %A Torres, Tomas %A Würthner, Frank %D 2023 %I American Chemical Society (ACS) %J ACS Materials Letters %P 543--548 %R 10.1021/acsmaterialslett.2c01132 %T Naphthalimide-Fused Subphthalocyanines: Electron-Deficient Materials Prepared by Cascade Annulation %U https://doi.org/10.1021%2Facsmaterialslett.2c01132 %X Imide-fused porphyrinoids are becoming key components in the area of molecular materials. Herein we report the synthesis of naphthalimide (NMI)-annulated subphthalocyanines (SubPcs) designed as an NIR-absorbing n-type organic semiconductor. Two different synthetic pathways could be applied for the preparation of NMI-fused SubPcs. The first consists of a [3 + 2] annulation between SubPc boronic ester and dibromo-NMI. This annulation, which involves the first CH activation reaction of a SubPc derivative reported so far, is totally regioselective to the β-position. Density functional theory (DFT) indicated that such position is favored both kinetically and thermodynamically. On the other hand, the second method relies on a cyclotrimerization of NMI-fused phthalonitrile. Electrochemical measurements and DFT calculations revealed that these NMI-fused SubPcs have low-lying LUMO energy levels suitable for electron charge transport. The N-alkyl substituted derivative (NMI-SubPc 2) was successfully applied as an nonfullerene acceptor (NFA) in combination with donor polymer PM6 in bulk-heterojunction (BHJ) organic solar cells (OSCs) with a highest power conversion efficiency (PCE) of 7.0%. This value is comparable to the record PCE of SubPc derivatives in BHJ-OSCs. Our results open a new vista in the preparation of π-extended contracted porphyrinoids and substantiate the potential of this new class of strong-absorbing electron-acceptor materials for applications in optoelectronic devices.
• Intersystem crossing of perylene bisimide neutral, radical anion, and dianion derivatives compared via ultrafast spectroelectrochemistry. Heitmüller, Julia; Fröhlich, Rebecca; Renner, Rebecca; Würthner, Frank; Brixner, Tobias. In Phys. Chem. Chem. Phys., 25(26), pp. 17214–17229. 2023.
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  Perylene bisimides are widely studied due to their various applications. Most research is carried out on neutral molecules but charged species are essential in the context of organic electronics and photovoltaics. In this study, we carry out ultrafast transient absorption spectroelectrochemistry and coherent two-dimensional electronic spectroelectrochemistry on three different neutral perylene bisimide derivatives as well as their singly and doubly reduced species. We compare an unsubstituted, flat parent perylene bisimide with two twisted ones that introduce spin–orbit coupling, leading to enhanced intersystem crossing. The internal conversion from higher excited states to the lowest electronically excited state occurs in the picosecond regime with lifetimes significantly shorter for the charged species compared to the neutral ones. Coherent oscillations of the transients for the flat dianion of parent perylene bisimide indicate the occurrence of Fermi resonance. The corresponding vibrational coupling and the superposition of the participating vibrational modes may lead to an enhanced charge separation and triplet formation.

  @article{D2CP05602J, abstract = {Perylene bisimides are widely studied due to their various applications. Most research is carried out on neutral molecules but charged species are essential in the context of organic electronics and photovoltaics. In this study, we carry out ultrafast transient absorption spectroelectrochemistry and coherent two-dimensional electronic spectroelectrochemistry on three different neutral perylene bisimide derivatives as well as their singly and doubly reduced species. We compare an unsubstituted, flat parent perylene bisimide with two twisted ones that introduce spin–orbit coupling, leading to enhanced intersystem crossing. The internal conversion from higher excited states to the lowest electronically excited state occurs in the picosecond regime with lifetimes significantly shorter for the charged species compared to the neutral ones. Coherent oscillations of the transients for the flat dianion of parent perylene bisimide indicate the occurrence of Fermi resonance. The corresponding vibrational coupling and the superposition of the participating vibrational modes may lead to an enhanced charge separation and triplet formation.}, author = {Heitmüller, Julia and Fröhlich, Rebecca and Renner, Rebecca and Würthner, Frank and Brixner, Tobias}, journal = {Phys. Chem. Chem. Phys.}, keywords = {myown}, number = 26, pages = {17214-17229}, title = {Intersystem crossing of perylene bisimide neutral, radical anion, and dianion derivatives compared via ultrafast spectroelectrochemistry}, volume = 25, year = 2023 }

  %0 Journal Article %1 D2CP05602J %A Heitmüller, Julia %A Fröhlich, Rebecca %A Renner, Rebecca %A Würthner, Frank %A Brixner, Tobias %D 2023 %J Phys. Chem. Chem. Phys. %N 26 %P 17214-17229 %R 10.1039/D2CP05602J %T Intersystem crossing of perylene bisimide neutral, radical anion, and dianion derivatives compared via ultrafast spectroelectrochemistry %U http://dx.doi.org/10.1039/D2CP05602J %V 25 %X Perylene bisimides are widely studied due to their various applications. Most research is carried out on neutral molecules but charged species are essential in the context of organic electronics and photovoltaics. In this study, we carry out ultrafast transient absorption spectroelectrochemistry and coherent two-dimensional electronic spectroelectrochemistry on three different neutral perylene bisimide derivatives as well as their singly and doubly reduced species. We compare an unsubstituted, flat parent perylene bisimide with two twisted ones that introduce spin–orbit coupling, leading to enhanced intersystem crossing. The internal conversion from higher excited states to the lowest electronically excited state occurs in the picosecond regime with lifetimes significantly shorter for the charged species compared to the neutral ones. Coherent oscillations of the transients for the flat dianion of parent perylene bisimide indicate the occurrence of Fermi resonance. The corresponding vibrational coupling and the superposition of the participating vibrational modes may lead to an enhanced charge separation and triplet formation.
• Synthesis and Properties of Achiral and Chiral Dipyrenoheteroles and Related Compounds. Malone, Ryan J.; Spengler, Jonas; Carmichael, Rachael A.; Ngo, Khoa; Würthner, Frank; Chalifoux, Wesley A. In Org. Lett., 25(1), pp. 226–230. 2023.
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  Achiral and chiral isomers of dipyrenoheteroles were synthesized via alkyne benzannulation. The electronic properties of these compounds were examined using cyclic voltammetry and differential pulse voltammetry. The enantiomers of the chiral isomers were separated, and their optical properties were examined in circular dichroism and circularly polarized luminescence studies. The chiral isomers exhibited a large bathochromic shift, relative to the achiral isomer, in both absorbance and fluorescence, resulting from decreased symmetry, rather than a change in the size of the backbone.

  @article{Malone_2023, abstract = {Achiral and chiral isomers of dipyrenoheteroles were synthesized via alkyne benzannulation. The electronic properties of these compounds were examined using cyclic voltammetry and differential pulse voltammetry. The enantiomers of the chiral isomers were separated, and their optical properties were examined in circular dichroism and circularly polarized luminescence studies. The chiral isomers exhibited a large bathochromic shift, relative to the achiral isomer, in both absorbance and fluorescence, resulting from decreased symmetry, rather than a change in the size of the backbone.}, author = {Malone, Ryan J. and Spengler, Jonas and Carmichael, Rachael A. and Ngo, Khoa and Würthner, Frank and Chalifoux, Wesley A.}, journal = {Org. Lett.}, keywords = {myown}, month = {01}, number = 1, pages = {226–230}, publisher = {American Chemical Society ({ACS})}, title = {Synthesis and Properties of Achiral and Chiral Dipyrenoheteroles and Related Compounds}, volume = 25, year = 2023 }

  %0 Journal Article %1 Malone_2023 %A Malone, Ryan J. %A Spengler, Jonas %A Carmichael, Rachael A. %A Ngo, Khoa %A Würthner, Frank %A Chalifoux, Wesley A. %D 2023 %I American Chemical Society (ACS) %J Org. Lett. %N 1 %P 226--230 %R 10.1021/acs.orglett.2c04071 %T Synthesis and Properties of Achiral and Chiral Dipyrenoheteroles and Related Compounds %U https://doi.org/10.1021%2Facs.orglett.2c04071 %V 25 %X Achiral and chiral isomers of dipyrenoheteroles were synthesized via alkyne benzannulation. The electronic properties of these compounds were examined using cyclic voltammetry and differential pulse voltammetry. The enantiomers of the chiral isomers were separated, and their optical properties were examined in circular dichroism and circularly polarized luminescence studies. The chiral isomers exhibited a large bathochromic shift, relative to the achiral isomer, in both absorbance and fluorescence, resulting from decreased symmetry, rather than a change in the size of the backbone.
• Donor–acceptor complex formation by social self-sorting of polycyclic aromatic hydrocarbons and perylene bisimides. Soldner, Simon; Anhalt, Olga; Sárosi, Menyhárt B.; Stolte, Matthias; Würthner, Frank. In Chem. Commun., 59(78), pp. 11656–11659. 2023.
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  Self-assembly versus complexation with polycyclic aromatic hydrocarbon (PAH) guest molecules is studied for a series of perylene bisimides (PBIs). Bulky imide substituents at the PBI guide their self-assembly into dimer aggregates with null-type exciton coupling. Host–guest titration experiments with perylene and triphenylene PAHs afford 1 : 1 and 1 : 2 complexes whose properties are studied by single crystal X-ray analysis and UV/Vis and fluorescence spectroscopy.

  @article{D3CC03704E, abstract = {Self-assembly versus complexation with polycyclic aromatic hydrocarbon (PAH) guest molecules is studied for a series of perylene bisimides (PBIs). Bulky imide substituents at the PBI guide their self-assembly into dimer aggregates with null-type exciton coupling. Host–guest titration experiments with perylene and triphenylene PAHs afford 1 : 1 and 1 : 2 complexes whose properties are studied by single crystal X-ray analysis and UV/Vis and fluorescence spectroscopy.}, author = {Soldner, Simon and Anhalt, Olga and Sárosi, Menyhárt B. and Stolte, Matthias and Würthner, Frank}, journal = {Chem. Commun.}, keywords = {myown}, number = 78, pages = {11656-11659}, title = {Donor–acceptor complex formation by social self-sorting of polycyclic aromatic hydrocarbons and perylene bisimides}, volume = 59, year = 2023 }

  %0 Journal Article %1 D3CC03704E %A Soldner, Simon %A Anhalt, Olga %A Sárosi, Menyhárt B. %A Stolte, Matthias %A Würthner, Frank %D 2023 %J Chem. Commun. %N 78 %P 11656-11659 %R 10.1039/D3CC03704E %T Donor–acceptor complex formation by social self-sorting of polycyclic aromatic hydrocarbons and perylene bisimides %U http://dx.doi.org/10.1039/D3CC03704E %V 59 %X Self-assembly versus complexation with polycyclic aromatic hydrocarbon (PAH) guest molecules is studied for a series of perylene bisimides (PBIs). Bulky imide substituents at the PBI guide their self-assembly into dimer aggregates with null-type exciton coupling. Host–guest titration experiments with perylene and triphenylene PAHs afford 1 : 1 and 1 : 2 complexes whose properties are studied by single crystal X-ray analysis and UV/Vis and fluorescence spectroscopy.
• C64 Nanographene Tetraimide - A Receptor for Phthalocyanines with Subnanomolar Affinity. Niyas, M. A.; Shoyama, Kazutaka; Würthner, Frank. In Angew. Chem. Int. Ed., 62(25). 2023.
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  Phthalocyanines are extensively used by the dye and pigment industry and in photovoltaic and photodynamic therapy research due to their intense absorption of visible light, outstanding stability, and versatility. As pigments, the unsubstituted phthalocyanines are insoluble owing to strong intermolecular π-π-stacking interactions, which causes limitations for the solution chemistry for both free base and metalated phthalocyanines. Here we show a supramolecular host–guest strategy to dissolve phthalocyanines into solution. C64 nanographene tetraimide (1) binds two free base/zinc/copper phthalocyanines in a 1 : 2 stoichiometry to solubilize phthalocyanines as evidenced by 1H NMR spectroscopy, UV/Vis absorption and single-crystal X-ray analysis. Binding studies using a tetra-tert-butyl-substituted soluble phthalocyanine revealed binding affinities of up to 109 M−1 in tetrachloromethane, relating to a Gibbs free energy of −52 kJ mol−1. Energy decomposition analysis revealed that complexes between 1 and phthalocyanines are stabilized by dispersion interactions followed by electrostatics as well as significant charge-transfer interactions.

  @article{Niyas_2023, abstract = {Phthalocyanines are extensively used by the dye and pigment industry and in photovoltaic and photodynamic therapy research due to their intense absorption of visible light, outstanding stability, and versatility. As pigments, the unsubstituted phthalocyanines are insoluble owing to strong intermolecular π-π-stacking interactions, which causes limitations for the solution chemistry for both free base and metalated phthalocyanines. Here we show a supramolecular host–guest strategy to dissolve phthalocyanines into solution. C64 nanographene tetraimide (1) binds two free base/zinc/copper phthalocyanines in a 1 : 2 stoichiometry to solubilize phthalocyanines as evidenced by 1H NMR spectroscopy, UV/Vis absorption and single-crystal X-ray analysis. Binding studies using a tetra-tert-butyl-substituted soluble phthalocyanine revealed binding affinities of up to 109 M−1 in tetrachloromethane, relating to a Gibbs free energy of −52 kJ mol−1. Energy decomposition analysis revealed that complexes between 1 and phthalocyanines are stabilized by dispersion interactions followed by electrostatics as well as significant charge-transfer interactions.}, author = {Niyas, M. A. and Shoyama, Kazutaka and Würthner, Frank}, journal = {Angew. Chem. Int. Ed.}, keywords = {myown}, month = {05}, number = 25, publisher = {Wiley}, title = {C64 Nanographene Tetraimide - A Receptor for Phthalocyanines with Subnanomolar Affinity}, volume = 62, year = 2023 }

  %0 Journal Article %1 Niyas_2023 %A Niyas, M. A. %A Shoyama, Kazutaka %A Würthner, Frank %D 2023 %I Wiley %J Angew. Chem. Int. Ed. %N 25 %R 10.1002/anie.202302032 %T C64 Nanographene Tetraimide - A Receptor for Phthalocyanines with Subnanomolar Affinity %U https://doi.org/10.1002%2Fanie.202302032 %V 62 %X Phthalocyanines are extensively used by the dye and pigment industry and in photovoltaic and photodynamic therapy research due to their intense absorption of visible light, outstanding stability, and versatility. As pigments, the unsubstituted phthalocyanines are insoluble owing to strong intermolecular π-π-stacking interactions, which causes limitations for the solution chemistry for both free base and metalated phthalocyanines. Here we show a supramolecular host–guest strategy to dissolve phthalocyanines into solution. C64 nanographene tetraimide (1) binds two free base/zinc/copper phthalocyanines in a 1 : 2 stoichiometry to solubilize phthalocyanines as evidenced by 1H NMR spectroscopy, UV/Vis absorption and single-crystal X-ray analysis. Binding studies using a tetra-tert-butyl-substituted soluble phthalocyanine revealed binding affinities of up to 109 M−1 in tetrachloromethane, relating to a Gibbs free energy of −52 kJ mol−1. Energy decomposition analysis revealed that complexes between 1 and phthalocyanines are stabilized by dispersion interactions followed by electrostatics as well as significant charge-transfer interactions.
• Controlling the Supramolecular Polymerization of Squaraine Dyes by a Molecular Chaperone Analogue. Kleine-Kleffmann, Lara; Stepanenko, Vladimir; Shoyama, Kazutaka; Wehner, Marius; Würthner, Frank. In J. Am. Chem. Soc., 145(16), pp. 9144–9151. 2023.
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  Molecular chaperones are proteins that assist in the (un)folding and (dis)assembly of other macromolecular structures toward their biologically functional state in a non-covalent manner. Transferring this concept from nature to artificial self-assembly processes, here, we show a new strategy to control supramolecular polymerization via a chaperone-like two-component system. A new kinetic trapping method was developed that enables efficient retardation of the spontaneous self-assembly of a squaraine dye monomer. The suppression of supramolecular polymerization could be regulated with a cofactor, which precisely initiates self-assembly. The presented system was investigated and characterized by ultraviolet–visible, Fourier transform infrared, and nuclear magnetic resonance spectroscopy, atomic force microscopy, isothermal titration calorimetry, and single-crystal X-ray diffraction. With these results, living supramolecular polymerization and block copolymer fabrication could be realized, demonstrating a new possibility for effective control over supramolecular polymerization processes.

  @article{Kleine_Kleffmann_2023, abstract = {Molecular chaperones are proteins that assist in the (un)folding and (dis)assembly of other macromolecular structures toward their biologically functional state in a non-covalent manner. Transferring this concept from nature to artificial self-assembly processes, here, we show a new strategy to control supramolecular polymerization via a chaperone-like two-component system. A new kinetic trapping method was developed that enables efficient retardation of the spontaneous self-assembly of a squaraine dye monomer. The suppression of supramolecular polymerization could be regulated with a cofactor, which precisely initiates self-assembly. The presented system was investigated and characterized by ultraviolet–visible, Fourier transform infrared, and nuclear magnetic resonance spectroscopy, atomic force microscopy, isothermal titration calorimetry, and single-crystal X-ray diffraction. With these results, living supramolecular polymerization and block copolymer fabrication could be realized, demonstrating a new possibility for effective control over supramolecular polymerization processes.}, author = {Kleine-Kleffmann, Lara and Stepanenko, Vladimir and Shoyama, Kazutaka and Wehner, Marius and Würthner, Frank}, journal = {J. Am. Chem. Soc.}, keywords = {myown}, month = {04}, number = 16, pages = {9144-9151}, publisher = {American Chemical Society (ACS)}, title = {Controlling the Supramolecular Polymerization of Squaraine Dyes by a Molecular Chaperone Analogue}, volume = 145, year = 2023 }

  %0 Journal Article %1 Kleine_Kleffmann_2023 %A Kleine-Kleffmann, Lara %A Stepanenko, Vladimir %A Shoyama, Kazutaka %A Wehner, Marius %A Würthner, Frank %D 2023 %I American Chemical Society (ACS) %J J. Am. Chem. Soc. %N 16 %P 9144-9151 %R 10.1021/jacs.3c01002 %T Controlling the Supramolecular Polymerization of Squaraine Dyes by a Molecular Chaperone Analogue %U https://doi.org/10.1021%2Fjacs.3c01002 %V 145 %X Molecular chaperones are proteins that assist in the (un)folding and (dis)assembly of other macromolecular structures toward their biologically functional state in a non-covalent manner. Transferring this concept from nature to artificial self-assembly processes, here, we show a new strategy to control supramolecular polymerization via a chaperone-like two-component system. A new kinetic trapping method was developed that enables efficient retardation of the spontaneous self-assembly of a squaraine dye monomer. The suppression of supramolecular polymerization could be regulated with a cofactor, which precisely initiates self-assembly. The presented system was investigated and characterized by ultraviolet–visible, Fourier transform infrared, and nuclear magnetic resonance spectroscopy, atomic force microscopy, isothermal titration calorimetry, and single-crystal X-ray diffraction. With these results, living supramolecular polymerization and block copolymer fabrication could be realized, demonstrating a new possibility for effective control over supramolecular polymerization processes.
• Naphthalimide-Annulated [n]Helicenes: Red Circularly Polarized Light Emitters. Tian, Xiaoqi; Shoyama, Kazutaka; Mahlmeister, Bernhard; Brust, Felix; Stolte, Matthias; Würthner, Frank. In J. Am. Chem. Soc., 145(17), pp. 9886–9894. 2023.
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  Two [n]heliceno-bis(naphthalimides) 1 and 2 (n = 5 and 6, respectively) where two electron-accepting naphthalimide moieties are attached at both ends of helicene core were synthesized by effective two-step strategy, and their enantiomers could be resolved by chiral stationary-phase high-performance liquid chromatography (HPLC). The single-crystal X-ray diffraction analysis of enantiopure fractions of 1 and 2 confirmed their helical structure, and together with experimental and calculated circular dichroism (CD) spectra, the absolute configuration was unambiguously assigned. Both 1 and 2 exhibit high molar extinction coefficients for the S0–S1 transition and high fluorescence quantum yields (73% for 1 and 69% for 2), both being outstanding for helicene derivatives. The red circularly polarized luminescence (CPL) emission up to 615 nm for 2 with CPL brightness (BCPL) up to 66.5 M–1 cm–1 demonstrates its potential for applications in chiral optoelectronics. Time-dependent density functional theory (TD-DFT) calculations unambiguously showed that the large transition magnetic dipole moment |m| of 2 is responsible for its high absorbance dissymmetry (gabs) and luminescence dissymmetry (glum) factor.

  @article{Tian_2023, abstract = {Two [n]heliceno-bis(naphthalimides) 1 and 2 (n = 5 and 6, respectively) where two electron-accepting naphthalimide moieties are attached at both ends of helicene core were synthesized by effective two-step strategy, and their enantiomers could be resolved by chiral stationary-phase high-performance liquid chromatography (HPLC). The single-crystal X-ray diffraction analysis of enantiopure fractions of 1 and 2 confirmed their helical structure, and together with experimental and calculated circular dichroism (CD) spectra, the absolute configuration was unambiguously assigned. Both 1 and 2 exhibit high molar extinction coefficients for the S0–S1 transition and high fluorescence quantum yields (73% for 1 and 69% for 2), both being outstanding for helicene derivatives. The red circularly polarized luminescence (CPL) emission up to 615 nm for 2 with CPL brightness (BCPL) up to 66.5 M–1 cm–1 demonstrates its potential for applications in chiral optoelectronics. Time-dependent density functional theory (TD-DFT) calculations unambiguously showed that the large transition magnetic dipole moment |m| of 2 is responsible for its high absorbance dissymmetry (gabs) and luminescence dissymmetry (glum) factor.}, author = {Tian, Xiaoqi and Shoyama, Kazutaka and Mahlmeister, Bernhard and Brust, Felix and Stolte, Matthias and Würthner, Frank}, journal = {J. Am. Chem. Soc.}, keywords = {myown}, month = {04}, number = 17, pages = {9886-9894}, publisher = {American Chemical Society (ACS)}, title = {Naphthalimide-Annulated [n]Helicenes: Red Circularly Polarized Light Emitters}, volume = 145, year = 2023 }

  %0 Journal Article %1 Tian_2023 %A Tian, Xiaoqi %A Shoyama, Kazutaka %A Mahlmeister, Bernhard %A Brust, Felix %A Stolte, Matthias %A Würthner, Frank %D 2023 %I American Chemical Society (ACS) %J J. Am. Chem. Soc. %N 17 %P 9886-9894 %R 10.1021/jacs.3c03441 %T Naphthalimide-Annulated [n]Helicenes: Red Circularly Polarized Light Emitters %U https://doi.org/10.1021%2Fjacs.3c03441 %V 145 %X Two [n]heliceno-bis(naphthalimides) 1 and 2 (n = 5 and 6, respectively) where two electron-accepting naphthalimide moieties are attached at both ends of helicene core were synthesized by effective two-step strategy, and their enantiomers could be resolved by chiral stationary-phase high-performance liquid chromatography (HPLC). The single-crystal X-ray diffraction analysis of enantiopure fractions of 1 and 2 confirmed their helical structure, and together with experimental and calculated circular dichroism (CD) spectra, the absolute configuration was unambiguously assigned. Both 1 and 2 exhibit high molar extinction coefficients for the S0–S1 transition and high fluorescence quantum yields (73% for 1 and 69% for 2), both being outstanding for helicene derivatives. The red circularly polarized luminescence (CPL) emission up to 615 nm for 2 with CPL brightness (BCPL) up to 66.5 M–1 cm–1 demonstrates its potential for applications in chiral optoelectronics. Time-dependent density functional theory (TD-DFT) calculations unambiguously showed that the large transition magnetic dipole moment |m| of 2 is responsible for its high absorbance dissymmetry (gabs) and luminescence dissymmetry (glum) factor.
• π-π Catalysis Made Asymmetric-Enantiomerization Catalysis Mediated by the Chiral π-System of a Perylene Bisimide Cyclophane. Weh, Manuel; Kroeger, Asja A.; Shoyama, Kazutaka; Grüne, Matthias; Karton, Amir; Würthner, Frank. In Angew. Chem. Int. Ed., 62(19). 2023.
  • [ Abstract ]
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  Enzymes actuate catalysis through a combination of transition state stabilization and ground state destabilization, inducing enantioselectivity through chiral binding sites. Here, we present a supramolecular model system which employs these basic principles to catalyze the enantiomerization of [5]helicene. Catalysis is hereby mediated not through a network of functional groups but through π-π catalysis exerted from the curved aromatic framework of a chiral perylene bisimide (PBI) cyclophane offering a binding pocket that is intricately complementary with the enantiomerization transition structure. Although transition state stabilization originates simply from dispersion and electrostatic interactions, enantiomerization kinetics are accelerated by a factor of ca. 700 at 295 K. Comparison with the meso-congener of the catalytically active cyclophane shows that upon configurational inversion in only one PBI moiety the catalytic effect is lost, highlighting the importance of precise transition structure recognition in supramolecular enzyme mimics.

  @article{Weh_2023, abstract = {Enzymes actuate catalysis through a combination of transition state stabilization and ground state destabilization, inducing enantioselectivity through chiral binding sites. Here, we present a supramolecular model system which employs these basic principles to catalyze the enantiomerization of [5]helicene. Catalysis is hereby mediated not through a network of functional groups but through π-π catalysis exerted from the curved aromatic framework of a chiral perylene bisimide (PBI) cyclophane offering a binding pocket that is intricately complementary with the enantiomerization transition structure. Although transition state stabilization originates simply from dispersion and electrostatic interactions, enantiomerization kinetics are accelerated by a factor of ca. 700 at 295 K. Comparison with the meso-congener of the catalytically active cyclophane shows that upon configurational inversion in only one PBI moiety the catalytic effect is lost, highlighting the importance of precise transition structure recognition in supramolecular enzyme mimics.}, author = {Weh, Manuel and Kroeger, Asja A. and Shoyama, Kazutaka and Grüne, Matthias and Karton, Amir and Würthner, Frank}, journal = {Angew. Chem. Int. Ed.}, keywords = {myown}, month = {04}, number = 19, publisher = {Wiley}, title = {π-π Catalysis Made Asymmetric-Enantiomerization Catalysis Mediated by the Chiral π-System of a Perylene Bisimide Cyclophane}, volume = 62, year = 2023 }

  %0 Journal Article %1 Weh_2023 %A Weh, Manuel %A Kroeger, Asja A. %A Shoyama, Kazutaka %A Grüne, Matthias %A Karton, Amir %A Würthner, Frank %D 2023 %I Wiley %J Angew. Chem. Int. Ed. %N 19 %R 10.1002/anie.202301301 %T π-π Catalysis Made Asymmetric-Enantiomerization Catalysis Mediated by the Chiral π-System of a Perylene Bisimide Cyclophane %U https://doi.org/10.1002%2Fanie.202301301 %V 62 %X Enzymes actuate catalysis through a combination of transition state stabilization and ground state destabilization, inducing enantioselectivity through chiral binding sites. Here, we present a supramolecular model system which employs these basic principles to catalyze the enantiomerization of [5]helicene. Catalysis is hereby mediated not through a network of functional groups but through π-π catalysis exerted from the curved aromatic framework of a chiral perylene bisimide (PBI) cyclophane offering a binding pocket that is intricately complementary with the enantiomerization transition structure. Although transition state stabilization originates simply from dispersion and electrostatic interactions, enantiomerization kinetics are accelerated by a factor of ca. 700 at 295 K. Comparison with the meso-congener of the catalytically active cyclophane shows that upon configurational inversion in only one PBI moiety the catalytic effect is lost, highlighting the importance of precise transition structure recognition in supramolecular enzyme mimics.
• Anomalous deep-red luminescence of perylene black analogues with strong π-π interactions. Tang, Ningning; Zhou, Jiadong; Wang, Liangxuan; Stolte, Matthias; Xie, Guojing; Wen, Xinbo; Liu, Linlin; Würthner, Frank; Gierschner, Johannes; Xie, Zengqi. In Nat. Commun., 14(1), p. 1922. 2023.
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  Perylene bisimide (PBI) dyes are known as red, maroon and black pigments, whose colors depend on the close π-π stacking arrangement. However, contrary to the luminescent monomers, deep-red and black PBI pigments are commonly non- or only weakly fluorescent due to (multiple) quenching pathways. Here, we introduce N-alkoxybenzyl substituted PBIs that contain close π stacking arrangement (exhibiting π-π ≈ 3.5 A, and longitudinal and transversal displacements of 3.1 A and 1.3 A; however, they afford deep-red emitters with solid-state fluorescence quantum yields (ΦF) of up to 60%. Systematic photophysical and computational studies in solution and in the solid state reveal a sensitive interconversion of the PBI-centred locally excited state and a charge transfer state, which depends on the dihedral angle ($\theta$) between the benzyl and alkoxy groups. This effectively controls the emission process, and enables high ΦF by circumventing the common quenching pathways commonly observed for perylene black analogues.

  @article{Tang2023, abstract = {Perylene bisimide (PBI) dyes are known as red, maroon and black pigments, whose colors depend on the close π-π stacking arrangement. However, contrary to the luminescent monomers, deep-red and black PBI pigments are commonly non- or only weakly fluorescent due to (multiple) quenching pathways. Here, we introduce N-alkoxybenzyl substituted PBIs that contain close π stacking arrangement (exhibiting π-π ≈ 3.5 A, and longitudinal and transversal displacements of 3.1 A and 1.3 A; however, they afford deep-red emitters with solid-state fluorescence quantum yields (ΦF) of up to 60%. Systematic photophysical and computational studies in solution and in the solid state reveal a sensitive interconversion of the PBI-centred locally excited state and a charge transfer state, which depends on the dihedral angle ($\theta$) between the benzyl and alkoxy groups. This effectively controls the emission process, and enables high ΦF by circumventing the common quenching pathways commonly observed for perylene black analogues.}, author = {Tang, Ningning and Zhou, Jiadong and Wang, Liangxuan and Stolte, Matthias and Xie, Guojing and Wen, Xinbo and Liu, Linlin and Würthner, Frank and Gierschner, Johannes and Xie, Zengqi}, journal = {Nat. Commun.}, keywords = {myown}, month = {04}, number = 1, pages = 1922, title = {Anomalous deep-red luminescence of perylene black analogues with strong π-π interactions}, volume = 14, year = 2023 }

  %0 Journal Article %1 Tang2023 %A Tang, Ningning %A Zhou, Jiadong %A Wang, Liangxuan %A Stolte, Matthias %A Xie, Guojing %A Wen, Xinbo %A Liu, Linlin %A Würthner, Frank %A Gierschner, Johannes %A Xie, Zengqi %D 2023 %J Nat. Commun. %N 1 %P 1922 %R 10.1038/s41467-023-37171-y %T Anomalous deep-red luminescence of perylene black analogues with strong π-π interactions %U https://doi.org/10.1038/s41467-023-37171-y %V 14 %X Perylene bisimide (PBI) dyes are known as red, maroon and black pigments, whose colors depend on the close π-π stacking arrangement. However, contrary to the luminescent monomers, deep-red and black PBI pigments are commonly non- or only weakly fluorescent due to (multiple) quenching pathways. Here, we introduce N-alkoxybenzyl substituted PBIs that contain close π stacking arrangement (exhibiting π-π ≈ 3.5 A, and longitudinal and transversal displacements of 3.1 A and 1.3 A; however, they afford deep-red emitters with solid-state fluorescence quantum yields (ΦF) of up to 60%. Systematic photophysical and computational studies in solution and in the solid state reveal a sensitive interconversion of the PBI-centred locally excited state and a charge transfer state, which depends on the dihedral angle ($\theta$) between the benzyl and alkoxy groups. This effectively controls the emission process, and enables high ΦF by circumventing the common quenching pathways commonly observed for perylene black analogues.
• Boron-, carbon-, and silicon-bridged 1,12-dihydroxy-perylene bisimides with tuned structural and optical properties. Nagler, Oliver; Shoyama, Kazutaka; Anhalt, Olga; Stolte, Matthias; Dubey, Rajeev K.; Xie, Zengqi; Würthner, Frank. In Org. Chem. Front., 10(22), pp. 5685–5697. 2023.
  • [ Abstract ]
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  Establishing suitable design strategies to tailor the functional properties of perylene bisimide (PBI) dyes is critical for their successful application in various devices. Herein, we report a new synthetic strategy to tune their structural and fluorescence properties by employing a 1,12-bay-substitution pattern that has been seldomly investigated in the past. Central to the strategy is the use of 1, 12-dihydroxy-PBI as a starting compound and the subsequent bridging of these hydroxy bay-functional groups with either a boron, carbon or silicon atom resulting in derivatives with a rigidified perylene core. This is followed by a detailed exploration of synthetic possibilities to functionalize the unsubstituted 6,7-positions at the opposite bay area to achieve novel perylene dyes with excellent structural and optical properties. The fluorescence color could be tuned from green to dark-orange while retaining the almost unity fluorescence quantum yield in solution. Moreover, a strong fluorescence with quantum yields as high as 40% has been observed for powders, which clearly illustrates the potential of the presented structural design to obtain new solid-state emitters.

  @article{D3QO01389H, abstract = {Establishing suitable design strategies to tailor the functional properties of perylene bisimide (PBI) dyes is critical for their successful application in various devices. Herein, we report a new synthetic strategy to tune their structural and fluorescence properties by employing a 1,12-bay-substitution pattern that has been seldomly investigated in the past. Central to the strategy is the use of 1, 12-dihydroxy-PBI as a starting compound and the subsequent bridging of these hydroxy bay-functional groups with either a boron, carbon or silicon atom resulting in derivatives with a rigidified perylene core. This is followed by a detailed exploration of synthetic possibilities to functionalize the unsubstituted 6,7-positions at the opposite bay area to achieve novel perylene dyes with excellent structural and optical properties. The fluorescence color could be tuned from green to dark-orange while retaining the almost unity fluorescence quantum yield in solution. Moreover, a strong fluorescence with quantum yields as high as 40% has been observed for powders, which clearly illustrates the potential of the presented structural design to obtain new solid-state emitters.}, author = {Nagler, Oliver and Shoyama, Kazutaka and Anhalt, Olga and Stolte, Matthias and Dubey, Rajeev K. and Xie, Zengqi and Würthner, Frank}, journal = {Org. Chem. Front.}, keywords = {myown}, number = 22, pages = {5685-5697}, title = {Boron-, carbon-, and silicon-bridged 1,12-dihydroxy-perylene bisimides with tuned structural and optical properties}, volume = 10, year = 2023 }

  %0 Journal Article %1 D3QO01389H %A Nagler, Oliver %A Shoyama, Kazutaka %A Anhalt, Olga %A Stolte, Matthias %A Dubey, Rajeev K. %A Xie, Zengqi %A Würthner, Frank %D 2023 %J Org. Chem. Front. %N 22 %P 5685-5697 %R 10.1039/D3QO01389H %T Boron-, carbon-, and silicon-bridged 1,12-dihydroxy-perylene bisimides with tuned structural and optical properties %U http://dx.doi.org/10.1039/D3QO01389H %V 10 %X Establishing suitable design strategies to tailor the functional properties of perylene bisimide (PBI) dyes is critical for their successful application in various devices. Herein, we report a new synthetic strategy to tune their structural and fluorescence properties by employing a 1,12-bay-substitution pattern that has been seldomly investigated in the past. Central to the strategy is the use of 1, 12-dihydroxy-PBI as a starting compound and the subsequent bridging of these hydroxy bay-functional groups with either a boron, carbon or silicon atom resulting in derivatives with a rigidified perylene core. This is followed by a detailed exploration of synthetic possibilities to functionalize the unsubstituted 6,7-positions at the opposite bay area to achieve novel perylene dyes with excellent structural and optical properties. The fluorescence color could be tuned from green to dark-orange while retaining the almost unity fluorescence quantum yield in solution. Moreover, a strong fluorescence with quantum yields as high as 40% has been observed for powders, which clearly illustrates the potential of the presented structural design to obtain new solid-state emitters.
• π-Extended benzo[1,2:4,5]di[7]annulene bis(dicarboximide)s – a new class of non-alternant polycyclic aromatic dicarboximides. Spengler, Jonas; Zhu, Chongwei; Shoyama, Kazutaka; Würthner, Frank. In Chem. Sci., 14(39), pp. 10861–10866. 2023.
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  Aromatic dicarboximides are a class of molecules represented by the well-known rylene bis(dicarboximide)s, in particular perylene or naphthalene bis(dicarboximide)s, which show pronounced optoelectronic properties and are applied as color pigments, fluorescent dyes and organic semiconductors. Herein we extend the family of aromatic bis(dicarboximide)s and report the synthesis of the first series of non-alternant aromatic dicarboximides by twofold Pd-catalyzed [5 + 2] annulation. Characterization by UV/vis spectroscopy and cyclic voltammetry (CV) measurements give insight into the optoelectronic characteristics of the hitherto unexplored substance class of heptagon-containing imides. Theoretical studies by nucleus independent chemical shift (NICS) XY-scans and anisotropy of the induced current density (ACID) plots demonstrate the influence of both the non-alternant carbon framework and the imide moieties on aromaticity of the synthesized bisimides.

  @article{D3SC04015A, abstract = {Aromatic dicarboximides are a class of molecules represented by the well-known rylene bis(dicarboximide)s, in particular perylene or naphthalene bis(dicarboximide)s, which show pronounced optoelectronic properties and are applied as color pigments, fluorescent dyes and organic semiconductors. Herein we extend the family of aromatic bis(dicarboximide)s and report the synthesis of the first series of non-alternant aromatic dicarboximides by twofold Pd-catalyzed [5 + 2] annulation. Characterization by UV/vis spectroscopy and cyclic voltammetry (CV) measurements give insight into the optoelectronic characteristics of the hitherto unexplored substance class of heptagon-containing imides. Theoretical studies by nucleus independent chemical shift (NICS) XY-scans and anisotropy of the induced current density (ACID) plots demonstrate the influence of both the non-alternant carbon framework and the imide moieties on aromaticity of the synthesized bisimides.}, author = {Spengler, Jonas and Zhu, Chongwei and Shoyama, Kazutaka and Würthner, Frank}, journal = {Chem. Sci.}, keywords = {myown}, number = 39, pages = {10861-10866}, title = {π-Extended benzo[1,2:4,5]di[7]annulene bis(dicarboximide)s – a new class of non-alternant polycyclic aromatic dicarboximides}, volume = 14, year = 2023 }

  %0 Journal Article %1 D3SC04015A %A Spengler, Jonas %A Zhu, Chongwei %A Shoyama, Kazutaka %A Würthner, Frank %D 2023 %J Chem. Sci. %N 39 %P 10861-10866 %R 10.1039/D3SC04015A %T π-Extended benzo[1,2:4,5]di[7]annulene bis(dicarboximide)s – a new class of non-alternant polycyclic aromatic dicarboximides %U http://dx.doi.org/10.1039/D3SC04015A %V 14 %X Aromatic dicarboximides are a class of molecules represented by the well-known rylene bis(dicarboximide)s, in particular perylene or naphthalene bis(dicarboximide)s, which show pronounced optoelectronic properties and are applied as color pigments, fluorescent dyes and organic semiconductors. Herein we extend the family of aromatic bis(dicarboximide)s and report the synthesis of the first series of non-alternant aromatic dicarboximides by twofold Pd-catalyzed [5 + 2] annulation. Characterization by UV/vis spectroscopy and cyclic voltammetry (CV) measurements give insight into the optoelectronic characteristics of the hitherto unexplored substance class of heptagon-containing imides. Theoretical studies by nucleus independent chemical shift (NICS) XY-scans and anisotropy of the induced current density (ACID) plots demonstrate the influence of both the non-alternant carbon framework and the imide moieties on aromaticity of the synthesized bisimides.
• Nitrogen-doped polycyclic aromatic hydrocarbons by a one-pot Suzuki coupling/intramolecular SNAr reaction. Tian, Xiaoqi; Shoyama, Kazutaka; Würthner, Frank. In Chem. Sci., 14(2), pp. 284–290. 2023.
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  We report a new method for the synthesis of nitrogen-doped (N-doped) polycyclic aromatic hydrocarbons (PAHs) by a Suzuki coupling/intramolecular SNAr cascade reaction. A one- or two-fold [3 + 3] naphtho-annulation of halogenated aniline was conducted under Suzuki–Miyaura cross-coupling conditions to yield a series of fully fused N-doped PAHs. In contrast to reported methods to synthesize pyridinic or pyrrolic nitrogen-doped PAHs, our method enables preparation of PAHs doped with graphitic nitrogen, for which few reports are known in the literature. The crystal structure as well as absorption, fluorescence and electrochemical properties of these N-doped PAHs were investigated, which demonstrated the capability of N-doping to adjust optical and electronic properties and alter the LUMO energy level.

  @article{D2SC05409D, abstract = {We report a new method for the synthesis of nitrogen-doped (N-doped) polycyclic aromatic hydrocarbons (PAHs) by a Suzuki coupling/intramolecular SNAr cascade reaction. A one- or two-fold [3 + 3] naphtho-annulation of halogenated aniline was conducted under Suzuki–Miyaura cross-coupling conditions to yield a series of fully fused N-doped PAHs. In contrast to reported methods to synthesize pyridinic or pyrrolic nitrogen-doped PAHs{,} our method enables preparation of PAHs doped with graphitic nitrogen{,} for which few reports are known in the literature. The crystal structure as well as absorption{,} fluorescence and electrochemical properties of these N-doped PAHs were investigated{,} which demonstrated the capability of N-doping to adjust optical and electronic properties and alter the LUMO energy level.}, author = {Tian, Xiaoqi and Shoyama, Kazutaka and Würthner, Frank}, journal = {Chem. Sci.}, keywords = {myown}, number = 2, pages = {284-290}, title = {Nitrogen-doped polycyclic aromatic hydrocarbons by a one-pot Suzuki coupling/intramolecular SNAr reaction}, volume = 14, year = 2023 }

  %0 Journal Article %1 D2SC05409D %A Tian, Xiaoqi %A Shoyama, Kazutaka %A Würthner, Frank %D 2023 %J Chem. Sci. %N 2 %P 284-290 %R 10.1039/D2SC05409D %T Nitrogen-doped polycyclic aromatic hydrocarbons by a one-pot Suzuki coupling/intramolecular SNAr reaction %U http://dx.doi.org/10.1039/D2SC05409D %V 14 %X We report a new method for the synthesis of nitrogen-doped (N-doped) polycyclic aromatic hydrocarbons (PAHs) by a Suzuki coupling/intramolecular SNAr cascade reaction. A one- or two-fold [3 + 3] naphtho-annulation of halogenated aniline was conducted under Suzuki–Miyaura cross-coupling conditions to yield a series of fully fused N-doped PAHs. In contrast to reported methods to synthesize pyridinic or pyrrolic nitrogen-doped PAHs, our method enables preparation of PAHs doped with graphitic nitrogen, for which few reports are known in the literature. The crystal structure as well as absorption, fluorescence and electrochemical properties of these N-doped PAHs were investigated, which demonstrated the capability of N-doping to adjust optical and electronic properties and alter the LUMO energy level.
• Growth of Merocyanine Dye J‐Aggregate Nanosheets by Living Supramolecular Polymerization. Kleine‐Kleffmann, Lara; Schulz, Alexander; Stepanenko, Vladimir; Würthner, Frank. In Angew. Chem. Int. Ed., 62(52). 2023.
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  @article{Kleine_Kleffmann_2023, author = {Kleine‐Kleffmann, Lara and Schulz, Alexander and Stepanenko, Vladimir and Würthner, Frank}, journal = {Angew. Chem. Int. Ed.}, keywords = {myown}, month = 11, number = 52, title = {Growth of Merocyanine Dye J‐Aggregate Nanosheets by Living Supramolecular Polymerization}, volume = 62, year = 2023 }

  %0 Journal Article %1 Kleine_Kleffmann_2023 %A Kleine‐Kleffmann, Lara %A Schulz, Alexander %A Stepanenko, Vladimir %A Würthner, Frank %D 2023 %J Angew. Chem. Int. Ed. %N 52 %R 10.1002/anie.202314667 %T Growth of Merocyanine Dye J‐Aggregate Nanosheets by Living Supramolecular Polymerization %U http://dx.doi.org/10.1002/anie.202314667 %V 62
• Unveiling the intersystem crossing dynamics in N-annulated perylene bisimides. Sunny, Jeswin; Sebastian, Ebin; Sujilkumar, Suvarna; Würthner, Frank; Engels, Bernd; Hariharan, Mahesh. In Phys. Chem. Chem. Phys., 41(25), pp. 28428–28436. 2023.
  • [ Abstract ]
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  The efficient population of the triplet excited states in heavy metal-free organic chromophores has been one of the long-standing research problems to molecular photochemists. The negligible spin–orbit coupling matrix elements in the purely organic chromophores and the large singlet–triplet energy gap (ΔES–T) pose a hurdle for ultrafast intersystem crossing (ISC). Herein we report the unprecedented population of triplet manifold in a series of nitrogen-annulated perylene bisimide chromophores (NPBI and Br-NPBI). NPBI is found to have a moderate fluorescence quantum yield (Φf = 68 ± 5%), whereas Br-NPBI showcased a low fluorescence quantum yield (Φf = 2.0 ± 0.6%) in toluene. The femtosecond transient absorption measurements of Br-NPBI revealed ultrafast ISC (kISC = 1.97 × 1010 s−1) from the initially populated singlet excited state to the long-lived triplet excited states. The triplet quantum yields (ΦT = 95.2 ± 4.6% for Br-NPBI, ΦT = 18.7 ± 2.3% for NPBI) calculated from nanosecond transient absorption spectroscopy measurements showed the enhancement in triplet population upon bromine substitution. The quantum chemical calculations revealed the explicit role of nitrogen annulation in tuning the excited state energy levels to favor the ISC. The near degeneracy between the singlet and triplet excited states observed in NPBI and Br-NPBI (ΔES–T = −0.01 eV for NPBI, ΔES–T = 0.03 eV for Br-NPBI) facilitates the spin flipping in the molecules. Nitrogen annulation emerges as a design strategy to open up the ISC pathway and the rate of which can be further enhanced by the substitution of a heavier element.

  @article{D3CP03888B, abstract = {The efficient population of the triplet excited states in heavy metal-free organic chromophores has been one of the long-standing research problems to molecular photochemists. The negligible spin–orbit coupling matrix elements in the purely organic chromophores and the large singlet–triplet energy gap (ΔES–T) pose a hurdle for ultrafast intersystem crossing (ISC). Herein we report the unprecedented population of triplet manifold in a series of nitrogen-annulated perylene bisimide chromophores (NPBI and Br-NPBI). NPBI is found to have a moderate fluorescence quantum yield (Φf = 68 ± 5%), whereas Br-NPBI showcased a low fluorescence quantum yield (Φf = 2.0 ± 0.6%) in toluene. The femtosecond transient absorption measurements of Br-NPBI revealed ultrafast ISC (kISC = 1.97 × 1010 s−1) from the initially populated singlet excited state to the long-lived triplet excited states. The triplet quantum yields (ΦT = 95.2 ± 4.6% for Br-NPBI, ΦT = 18.7 ± 2.3% for NPBI) calculated from nanosecond transient absorption spectroscopy measurements showed the enhancement in triplet population upon bromine substitution. The quantum chemical calculations revealed the explicit role of nitrogen annulation in tuning the excited state energy levels to favor the ISC. The near degeneracy between the singlet and triplet excited states observed in NPBI and Br-NPBI (ΔES–T = −0.01 eV for NPBI{,} ΔES–T = 0.03 eV for Br-NPBI) facilitates the spin flipping in the molecules. Nitrogen annulation emerges as a design strategy to open up the ISC pathway and the rate of which can be further enhanced by the substitution of a heavier element.}, author = {Sunny, Jeswin and Sebastian, Ebin and Sujilkumar, Suvarna and Würthner, Frank and Engels, Bernd and Hariharan, Mahesh}, journal = {Phys. Chem. Chem. Phys.}, keywords = {myown}, number = 25, pages = {28428–28436}, title = {Unveiling the intersystem crossing dynamics in N-annulated perylene bisimides}, volume = 41, year = 2023 }

  %0 Journal Article %1 D3CP03888B %A Sunny, Jeswin %A Sebastian, Ebin %A Sujilkumar, Suvarna %A Würthner, Frank %A Engels, Bernd %A Hariharan, Mahesh %D 2023 %J Phys. Chem. Chem. Phys. %N 25 %P 28428–28436 %R 10.1039/D3CP03888B %T Unveiling the intersystem crossing dynamics in N-annulated perylene bisimides %U http://dx.doi.org/10.1039/D3CP03888B %V 41 %X The efficient population of the triplet excited states in heavy metal-free organic chromophores has been one of the long-standing research problems to molecular photochemists. The negligible spin–orbit coupling matrix elements in the purely organic chromophores and the large singlet–triplet energy gap (ΔES–T) pose a hurdle for ultrafast intersystem crossing (ISC). Herein we report the unprecedented population of triplet manifold in a series of nitrogen-annulated perylene bisimide chromophores (NPBI and Br-NPBI). NPBI is found to have a moderate fluorescence quantum yield (Φf = 68 ± 5%), whereas Br-NPBI showcased a low fluorescence quantum yield (Φf = 2.0 ± 0.6%) in toluene. The femtosecond transient absorption measurements of Br-NPBI revealed ultrafast ISC (kISC = 1.97 × 1010 s−1) from the initially populated singlet excited state to the long-lived triplet excited states. The triplet quantum yields (ΦT = 95.2 ± 4.6% for Br-NPBI, ΦT = 18.7 ± 2.3% for NPBI) calculated from nanosecond transient absorption spectroscopy measurements showed the enhancement in triplet population upon bromine substitution. The quantum chemical calculations revealed the explicit role of nitrogen annulation in tuning the excited state energy levels to favor the ISC. The near degeneracy between the singlet and triplet excited states observed in NPBI and Br-NPBI (ΔES–T = −0.01 eV for NPBI, ΔES–T = 0.03 eV for Br-NPBI) facilitates the spin flipping in the molecules. Nitrogen annulation emerges as a design strategy to open up the ISC pathway and the rate of which can be further enhanced by the substitution of a heavier element.

• Macrocyclic Donor-Acceptor Dyads Composed of Oligothiophene Half-Cycles and Perylene Bisimides. Bold, Kevin; Stolte, Matthias; Shoyama, Kazutaka; Krause, Ana-Maria; Schmiedel, Alexander; Holzapfel, Marco; Lambert, Christoph; Würthner, Frank. In Chem. Eur. J., 28(30). 2022.
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  A series of donor-acceptor (D−A) macrocyclic dyads consisting of an electron-poor perylene bisimide (PBI) π-scaffold bridged with electron-rich α-oligothiophenes bearing four, five, six and seven thiophene units between the two phenyl-imide substituents has been synthesized and characterized by steady-state UV/Vis absorption and fluorescence spectroscopy, cyclic and differential pulse voltammetry as well as transient absorption spectroscopy. Tying the oligothiophene strands in a conformationally fixed macrocyclic arrangement leads to a more rigid π-scaffold with vibronic fine structure in the respective absorption spectra. Electrochemical analysis disclosed charged state properties in solution which are strongly dependent on the degree of rigidification within the individual macrocycle. Investigation of the excited state dynamics revealed an oligothiophene bridge size-dependent fast charge transfer process for the macrocyclic dyads upon PBI subunit excitation.

  @article{Bold_2022, abstract = {A series of donor-acceptor (D−A) macrocyclic dyads consisting of an electron-poor perylene bisimide (PBI) π-scaffold bridged with electron-rich α-oligothiophenes bearing four, five, six and seven thiophene units between the two phenyl-imide substituents has been synthesized and characterized by steady-state UV/Vis absorption and fluorescence spectroscopy, cyclic and differential pulse voltammetry as well as transient absorption spectroscopy. Tying the oligothiophene strands in a conformationally fixed macrocyclic arrangement leads to a more rigid π-scaffold with vibronic fine structure in the respective absorption spectra. Electrochemical analysis disclosed charged state properties in solution which are strongly dependent on the degree of rigidification within the individual macrocycle. Investigation of the excited state dynamics revealed an oligothiophene bridge size-dependent fast charge transfer process for the macrocyclic dyads upon PBI subunit excitation.}, author = {Bold, Kevin and Stolte, Matthias and Shoyama, Kazutaka and Krause, Ana-Maria and Schmiedel, Alexander and Holzapfel, Marco and Lambert, Christoph and Würthner, Frank}, journal = {Chem. Eur. J.}, keywords = {myown}, month = {04}, number = 30, publisher = {Wiley}, title = {Macrocyclic Donor-Acceptor Dyads Composed of Oligothiophene Half-Cycles and Perylene Bisimides}, volume = 28, year = 2022 }

  %0 Journal Article %1 Bold_2022 %A Bold, Kevin %A Stolte, Matthias %A Shoyama, Kazutaka %A Krause, Ana-Maria %A Schmiedel, Alexander %A Holzapfel, Marco %A Lambert, Christoph %A Würthner, Frank %D 2022 %I Wiley %J Chem. Eur. J. %N 30 %R 10.1002/chem.202200355 %T Macrocyclic Donor-Acceptor Dyads Composed of Oligothiophene Half-Cycles and Perylene Bisimides %U https://doi.org/10.1002%2Fchem.202200355 %V 28 %X A series of donor-acceptor (D−A) macrocyclic dyads consisting of an electron-poor perylene bisimide (PBI) π-scaffold bridged with electron-rich α-oligothiophenes bearing four, five, six and seven thiophene units between the two phenyl-imide substituents has been synthesized and characterized by steady-state UV/Vis absorption and fluorescence spectroscopy, cyclic and differential pulse voltammetry as well as transient absorption spectroscopy. Tying the oligothiophene strands in a conformationally fixed macrocyclic arrangement leads to a more rigid π-scaffold with vibronic fine structure in the respective absorption spectra. Electrochemical analysis disclosed charged state properties in solution which are strongly dependent on the degree of rigidification within the individual macrocycle. Investigation of the excited state dynamics revealed an oligothiophene bridge size-dependent fast charge transfer process for the macrocyclic dyads upon PBI subunit excitation.
• Pure Boric Acid Does Not Show Room-Temperature Phosphorescence (RTP). Wu, Zhu; Roldao, Juan Carlos; Rauch, Florian; Friedrich, Alexandra; Ferger, Matthias; Würthner, Frank; Gierschner, Johannes; Marder, Todd B. In Angew. Chem. Int. Ed., 61(15). 2022.
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  Boric acid (BA) has been used as a transparent glass matrix for optical materials for over 100 years. However, recently, apparent room-temperature phosphorescence (RTP) from BA (crystalline and powder states) was reported (Zheng et al., Angew. Chem. Int. Ed. 2021, 60, 9500) when irradiated at 280 nm under ambient conditions. We suspected that RTP from their BA sample was induced by an unidentified impurity. Our experimental results show that pure BA synthesized from B(OMe)3 does not luminesce in the solid state when irradiated at 250–400 nm, while commercial BA indeed (faintly) luminesces. Our theoretical calculations show that neither individual BA molecules nor aggregates would absorb light at >175 nm, and we observe no absorption of solid pure BA experimentally at >200 nm. Therefore, it is not possible for pure BA to be excited at >250 nm even in the solid state. Thus, pure BA does not display RTP, whereas trace impurities can induce RTP.

  @article{Wu_2022, abstract = {Boric acid (BA) has been used as a transparent glass matrix for optical materials for over 100 years. However, recently, apparent room-temperature phosphorescence (RTP) from BA (crystalline and powder states) was reported (Zheng et al., Angew. Chem. Int. Ed. 2021, 60, 9500) when irradiated at 280 nm under ambient conditions. We suspected that RTP from their BA sample was induced by an unidentified impurity. Our experimental results show that pure BA synthesized from B(OMe)3 does not luminesce in the solid state when irradiated at 250–400 nm, while commercial BA indeed (faintly) luminesces. Our theoretical calculations show that neither individual BA molecules nor aggregates would absorb light at >175 nm, and we observe no absorption of solid pure BA experimentally at >200 nm. Therefore, it is not possible for pure BA to be excited at >250 nm even in the solid state. Thus, pure BA does not display RTP, whereas trace impurities can induce RTP.}, author = {Wu, Zhu and Roldao, Juan Carlos and Rauch, Florian and Friedrich, Alexandra and Ferger, Matthias and Würthner, Frank and Gierschner, Johannes and Marder, Todd B.}, journal = {Angew. Chem. Int. Ed.}, keywords = {myown}, month = {02}, number = 15, publisher = {Wiley}, title = {Pure Boric Acid Does Not Show Room-Temperature Phosphorescence (RTP)}, volume = 61, year = 2022 }

  %0 Journal Article %1 Wu_2022 %A Wu, Zhu %A Roldao, Juan Carlos %A Rauch, Florian %A Friedrich, Alexandra %A Ferger, Matthias %A Würthner, Frank %A Gierschner, Johannes %A Marder, Todd B. %D 2022 %I Wiley %J Angew. Chem. Int. Ed. %N 15 %R 10.1002/anie.202200599 %T Pure Boric Acid Does Not Show Room-Temperature Phosphorescence (RTP) %U https://doi.org/10.1002%2Fanie.202200599 %V 61 %X Boric acid (BA) has been used as a transparent glass matrix for optical materials for over 100 years. However, recently, apparent room-temperature phosphorescence (RTP) from BA (crystalline and powder states) was reported (Zheng et al., Angew. Chem. Int. Ed. 2021, 60, 9500) when irradiated at 280 nm under ambient conditions. We suspected that RTP from their BA sample was induced by an unidentified impurity. Our experimental results show that pure BA synthesized from B(OMe)3 does not luminesce in the solid state when irradiated at 250–400 nm, while commercial BA indeed (faintly) luminesces. Our theoretical calculations show that neither individual BA molecules nor aggregates would absorb light at >175 nm, and we observe no absorption of solid pure BA experimentally at >200 nm. Therefore, it is not possible for pure BA to be excited at >250 nm even in the solid state. Thus, pure BA does not display RTP, whereas trace impurities can induce RTP.
• Ultrafast Symmetry-Breaking Charge Separation in a Perylene Bisimide Dimer Enabled by Vibronic Coupling and Breakdown of Adiabaticity. Hong, Yongseok; Schlosser, Felix; Kim, Woojae; Würthner, Frank; Kim, Dongho. In J. Am. Chem. Soc., 144(34), pp. 15539–15548. 2022.
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  Perylene bisimides (PBIs) have received great attention in their applicability to optoelectronics. Especially, symmetry-breaking charge separation (SB-CS) in PBIs has been investigated to mimic the efficient light capturing and charge generation in natural light-harvesting systems. However, unlike ultrafast CS dynamics in donor–acceptor heterojunction materials, ultrafast SB-CS in a stacked homodimer has still been challenging due to excimer formation in the absence of rigidifying surroundings such as a special pair in the natural systems. Herein, we present the detailed mechanism of ultrafast photoinduced SB-CS occurring in a 1,7-bis(N-pyrrolidinyl) PBI dimer within a cyclophane. Through narrow-band and broad-band transient absorption spectroscopy, we demonstrate that ultrafast SB-CS in the dimer is enabled by the combination of (1) vibrationally coherent charge-transfer resonance-enhanced excimer formation and (2) breakdown of adiabaticity (formation of SB-CS diabats) in the excimer state via structural and solvent fluctuation. Quantum chemical calculations also underpin that the participation of strong electron-donating substituents in overall vibrational modes plays a crucial role in triggering the ultrafast SB-CS. Therefore, our work provides an alternative route to facilitate ultrafast SB-CS in PBIs and thereby establishes a novel strategy for the design of optoelectronic materials.

  @article{Hong_2022, abstract = {Perylene bisimides (PBIs) have received great attention in their applicability to optoelectronics. Especially, symmetry-breaking charge separation (SB-CS) in PBIs has been investigated to mimic the efficient light capturing and charge generation in natural light-harvesting systems. However, unlike ultrafast CS dynamics in donor–acceptor heterojunction materials, ultrafast SB-CS in a stacked homodimer has still been challenging due to excimer formation in the absence of rigidifying surroundings such as a special pair in the natural systems. Herein, we present the detailed mechanism of ultrafast photoinduced SB-CS occurring in a 1,7-bis(N-pyrrolidinyl) PBI dimer within a cyclophane. Through narrow-band and broad-band transient absorption spectroscopy, we demonstrate that ultrafast SB-CS in the dimer is enabled by the combination of (1) vibrationally coherent charge-transfer resonance-enhanced excimer formation and (2) breakdown of adiabaticity (formation of SB-CS diabats) in the excimer state via structural and solvent fluctuation. Quantum chemical calculations also underpin that the participation of strong electron-donating substituents in overall vibrational modes plays a crucial role in triggering the ultrafast SB-CS. Therefore, our work provides an alternative route to facilitate ultrafast SB-CS in PBIs and thereby establishes a novel strategy for the design of optoelectronic materials.}, author = {Hong, Yongseok and Schlosser, Felix and Kim, Woojae and Würthner, Frank and Kim, Dongho}, journal = {J. Am. Chem. Soc.}, keywords = {myown}, month = {08}, number = 34, pages = {15539–15548}, publisher = {American Chemical Society ({ACS})}, title = {Ultrafast Symmetry-Breaking Charge Separation in a Perylene Bisimide Dimer Enabled by Vibronic Coupling and Breakdown of Adiabaticity}, volume = 144, year = 2022 }

  %0 Journal Article %1 Hong_2022 %A Hong, Yongseok %A Schlosser, Felix %A Kim, Woojae %A Würthner, Frank %A Kim, Dongho %D 2022 %I American Chemical Society (ACS) %J J. Am. Chem. Soc. %N 34 %P 15539--15548 %R 10.1021/jacs.2c03916 %T Ultrafast Symmetry-Breaking Charge Separation in a Perylene Bisimide Dimer Enabled by Vibronic Coupling and Breakdown of Adiabaticity %U https://doi.org/10.1021%2Fjacs.2c03916 %V 144 %X Perylene bisimides (PBIs) have received great attention in their applicability to optoelectronics. Especially, symmetry-breaking charge separation (SB-CS) in PBIs has been investigated to mimic the efficient light capturing and charge generation in natural light-harvesting systems. However, unlike ultrafast CS dynamics in donor–acceptor heterojunction materials, ultrafast SB-CS in a stacked homodimer has still been challenging due to excimer formation in the absence of rigidifying surroundings such as a special pair in the natural systems. Herein, we present the detailed mechanism of ultrafast photoinduced SB-CS occurring in a 1,7-bis(N-pyrrolidinyl) PBI dimer within a cyclophane. Through narrow-band and broad-band transient absorption spectroscopy, we demonstrate that ultrafast SB-CS in the dimer is enabled by the combination of (1) vibrationally coherent charge-transfer resonance-enhanced excimer formation and (2) breakdown of adiabaticity (formation of SB-CS diabats) in the excimer state via structural and solvent fluctuation. Quantum chemical calculations also underpin that the participation of strong electron-donating substituents in overall vibrational modes plays a crucial role in triggering the ultrafast SB-CS. Therefore, our work provides an alternative route to facilitate ultrafast SB-CS in PBIs and thereby establishes a novel strategy for the design of optoelectronic materials.
• Enantioselective Recognition of Helicenes by a Tailored Chiral Benzo[ghi]perylene Trisimide pi-Scaffold. Teichmann, Ben; Krause, Ana-Maria; Lin, Mei-Jin; Würthner, Frank. In Angew. Chem. Int. Ed., 61(15). 2022.
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  Enantioselective molecular recognition of chiral molecules that lack specific interaction sites for hydrogen bonding or Lewis acid–base interactions remains challenging. Here we introduce the concept of tailored chiral π-surfaces toward the maximization of shape complementarity. As we demonstrate for helicenes it is indeed possible by pure van-der-Waals interactions (π–π interactions and CH–π interactions) to accomplish enantioselective binding. This is shown for a novel benzo[ghi]perylene trisimide (BPTI) receptor whose π-scaffold is contorted into a chiral plane by functionalization with 1,1′-bi-2-naphthol (BINOL). Complexation experiments of enantiopure (P)-BPTI with (P)- and (M)-[6]helicene afforded binding constants of 10 700 M−1 and 550 M−1, respectively, thereby demonstrating the pronounced enantiodifferentiation by the homochiral π-scaffold of the BPTI host. The enantioselective recognition is even observable by the naked eye due to a specific exciplex-type emission originating from the interacting homochiral π-scaffolds of electron-rich [6]helicene and electron-poor BPTI.

  @article{Teichmann_2022, abstract = {Enantioselective molecular recognition of chiral molecules that lack specific interaction sites for hydrogen bonding or Lewis acid–base interactions remains challenging. Here we introduce the concept of tailored chiral π-surfaces toward the maximization of shape complementarity. As we demonstrate for helicenes it is indeed possible by pure van-der-Waals interactions (π–π interactions and CH–π interactions) to accomplish enantioselective binding. This is shown for a novel benzo[ghi]perylene trisimide (BPTI) receptor whose π-scaffold is contorted into a chiral plane by functionalization with 1,1′-bi-2-naphthol (BINOL). Complexation experiments of enantiopure (P)-BPTI with (P)- and (M)-[6]helicene afforded binding constants of 10 700 M−1 and 550 M−1, respectively, thereby demonstrating the pronounced enantiodifferentiation by the homochiral π-scaffold of the BPTI host. The enantioselective recognition is even observable by the naked eye due to a specific exciplex-type emission originating from the interacting homochiral π-scaffolds of electron-rich [6]helicene and electron-poor BPTI.}, author = {Teichmann, Ben and Krause, Ana-Maria and Lin, Mei-Jin and Würthner, Frank}, journal = {Angew. Chem. Int. Ed.}, keywords = {myown}, month = {02}, number = 15, publisher = {Wiley}, title = {Enantioselective Recognition of Helicenes by a Tailored Chiral Benzo[ghi]perylene Trisimide pi-Scaffold}, volume = 61, year = 2022 }

  %0 Journal Article %1 Teichmann_2022 %A Teichmann, Ben %A Krause, Ana-Maria %A Lin, Mei-Jin %A Würthner, Frank %D 2022 %I Wiley %J Angew. Chem. Int. Ed. %N 15 %R 10.1002/anie.202117625 %T Enantioselective Recognition of Helicenes by a Tailored Chiral Benzo[ghi]perylene Trisimide pi-Scaffold %U https://doi.org/10.1002%2Fanie.202117625 %V 61 %X Enantioselective molecular recognition of chiral molecules that lack specific interaction sites for hydrogen bonding or Lewis acid–base interactions remains challenging. Here we introduce the concept of tailored chiral π-surfaces toward the maximization of shape complementarity. As we demonstrate for helicenes it is indeed possible by pure van-der-Waals interactions (π–π interactions and CH–π interactions) to accomplish enantioselective binding. This is shown for a novel benzo[ghi]perylene trisimide (BPTI) receptor whose π-scaffold is contorted into a chiral plane by functionalization with 1,1′-bi-2-naphthol (BINOL). Complexation experiments of enantiopure (P)-BPTI with (P)- and (M)-[6]helicene afforded binding constants of 10 700 M−1 and 550 M−1, respectively, thereby demonstrating the pronounced enantiodifferentiation by the homochiral π-scaffold of the BPTI host. The enantioselective recognition is even observable by the naked eye due to a specific exciplex-type emission originating from the interacting homochiral π-scaffolds of electron-rich [6]helicene and electron-poor BPTI.
• Tuning Exciton Coupling of Merocyanine Nucleoside Dimers by RNA, DNA and GNA Double Helix Conformations. Dietzsch, Julia; Bialas, David; Bandorf, Johannes; Würthner, Frank; Höbartner, Claudia. In Angew. Chem. Int. Ed., 61(9). 2022.
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  Exciton coupling between two or more chromophores in a specific environment is a key mechanism associated with color tuning and modulation of absorption energies. This concept is well exemplified by natural photosynthetic proteins, and can also be achieved in synthetic nucleic acid nanostructures. Here we report the coupling of barbituric acid merocyanine (BAM) nucleoside analogues and show that exciton coupling can be tuned by the double helix conformation. BAM is a nucleobase mimic that was incorporated in the phosphodiester backbone of RNA, DNA and GNA oligonucleotides. Duplexes with different backbone constitutions and geometries afforded different mutual dye arrangements, leading to distinct optical signatures due to competing modes of chromophore organization via electrostatic, dipolar, π–π-stacking and hydrogen-bonding interactions. The realized supramolecular motifs include hydrogenbonded BAM–adenine base pairs and antiparallel as well as rotationally stacked BAM dimer aggregates with distinct absorption, CD and fluorescence properties.

  @article{Dietzsch_2022, abstract = {Exciton coupling between two or more chromophores in a specific environment is a key mechanism associated with color tuning and modulation of absorption energies. This concept is well exemplified by natural photosynthetic proteins, and can also be achieved in synthetic nucleic acid nanostructures. Here we report the coupling of barbituric acid merocyanine (BAM) nucleoside analogues and show that exciton coupling can be tuned by the double helix conformation. BAM is a nucleobase mimic that was incorporated in the phosphodiester backbone of RNA, DNA and GNA oligonucleotides. Duplexes with different backbone constitutions and geometries afforded different mutual dye arrangements, leading to distinct optical signatures due to competing modes of chromophore organization via electrostatic, dipolar, π–π-stacking and hydrogen-bonding interactions. The realized supramolecular motifs include hydrogenbonded BAM–adenine base pairs and antiparallel as well as rotationally stacked BAM dimer aggregates with distinct absorption, CD and fluorescence properties.}, author = {Dietzsch, Julia and Bialas, David and Bandorf, Johannes and Würthner, Frank and Höbartner, Claudia}, journal = {Angew. Chem. Int. Ed.}, keywords = {myown}, month = {01}, number = 9, publisher = {Wiley}, title = {Tuning Exciton Coupling of Merocyanine Nucleoside Dimers by RNA, DNA and GNA Double Helix Conformations}, volume = 61, year = 2022 }

  %0 Journal Article %1 Dietzsch_2022 %A Dietzsch, Julia %A Bialas, David %A Bandorf, Johannes %A Würthner, Frank %A Höbartner, Claudia %D 2022 %I Wiley %J Angew. Chem. Int. Ed. %N 9 %R 10.1002/anie.202116783 %T Tuning Exciton Coupling of Merocyanine Nucleoside Dimers by RNA, DNA and GNA Double Helix Conformations %U https://doi.org/10.1002%2Fanie.202116783 %V 61 %X Exciton coupling between two or more chromophores in a specific environment is a key mechanism associated with color tuning and modulation of absorption energies. This concept is well exemplified by natural photosynthetic proteins, and can also be achieved in synthetic nucleic acid nanostructures. Here we report the coupling of barbituric acid merocyanine (BAM) nucleoside analogues and show that exciton coupling can be tuned by the double helix conformation. BAM is a nucleobase mimic that was incorporated in the phosphodiester backbone of RNA, DNA and GNA oligonucleotides. Duplexes with different backbone constitutions and geometries afforded different mutual dye arrangements, leading to distinct optical signatures due to competing modes of chromophore organization via electrostatic, dipolar, π–π-stacking and hydrogen-bonding interactions. The realized supramolecular motifs include hydrogenbonded BAM–adenine base pairs and antiparallel as well as rotationally stacked BAM dimer aggregates with distinct absorption, CD and fluorescence properties.
• Self-Assembly of a Zinc Bacteriochlorophyll-d Analog with a Lipophilic Tertiary Amide Group in the 17-Substituent. Shoji, Sunao; Stepanenko, Vladimir; Würthner, Frank; Tamiaki, Hitoshi. In Bull. Chem. Soc. Jpn., 95(7), pp. 1083–1085. 2022.
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  Self-assembled aggregates of bacteriochlorophyll(BChl)-c/d/e pigments play key roles in major light-harvesting antenna systems of photosynthetic green bacteria. Herein, we report the self-assembly of a lipophilic zinc BChl-d model with an N,N-didodecylamide in the 17-substituent. The present model formed two types of J-aggregates, which formed under kinetic and thermodynamic controls.

  @article{Shoji_2022, abstract = {Self-assembled aggregates of bacteriochlorophyll(BChl)-c/d/e pigments play key roles in major light-harvesting antenna systems of photosynthetic green bacteria. Herein, we report the self-assembly of a lipophilic zinc BChl-d model with an N,N-didodecylamide in the 17-substituent. The present model formed two types of J-aggregates, which formed under kinetic and thermodynamic controls.}, author = {Shoji, Sunao and Stepanenko, Vladimir and Würthner, Frank and Tamiaki, Hitoshi}, journal = {Bull. Chem. Soc. Jpn.}, keywords = {myown}, month = {07}, number = 7, pages = {1083–1085}, publisher = {The Chemical Society of Japan}, title = {Self-Assembly of a Zinc Bacteriochlorophyll-d Analog with a Lipophilic Tertiary Amide Group in the 17-Substituent}, volume = 95, year = 2022 }

  %0 Journal Article %1 Shoji_2022 %A Shoji, Sunao %A Stepanenko, Vladimir %A Würthner, Frank %A Tamiaki, Hitoshi %D 2022 %I The Chemical Society of Japan %J Bull. Chem. Soc. Jpn. %N 7 %P 1083--1085 %R 10.1246/bcsj.20220128 %T Self-Assembly of a Zinc Bacteriochlorophyll-d Analog with a Lipophilic Tertiary Amide Group in the 17-Substituent %U https://doi.org/10.1246%2Fbcsj.20220128 %V 95 %X Self-assembled aggregates of bacteriochlorophyll(BChl)-c/d/e pigments play key roles in major light-harvesting antenna systems of photosynthetic green bacteria. Herein, we report the self-assembly of a lipophilic zinc BChl-d model with an N,N-didodecylamide in the 17-substituent. The present model formed two types of J-aggregates, which formed under kinetic and thermodynamic controls.
• Supramolecular p/n-heterojunction of C60-functionalized bis(merocyanine) quadruple stack: A model system for charge carrier separation and recombination in organic solar cells. Bialas, David; Fennel, Franziska; Noll, Niklas; Holzapfel, Marco; Schmiedel, Alexander; Lambert, Christoph; Würthner, Frank. In Nat. Sci., 2(2). 2022.
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  Supramolecular photosystems can afford important insights into elementary processes in molecular materials. Here, a bis(merocyanine)-C60 conjugate composed of two covalently tethered electron-donating merocyanine chromophores and two appended fullerene electron acceptor units is investigated. Concentration-dependent UV/Vis studies in nonpolar solvents revealed a bimolecular association (dimerization) process, resulting in the formation of an H-coupled merocyanine dye aggregate. The aggregate structure was confirmed by 2D NMR spectroscopy proving the presence of a well-defined quadruple dye stack surrounded by four loosely connected fullerenes, which mimics the donor–acceptor interface in bulk heterojunction (BHJ) solar cells. Due to the interdigitation of the dyes in the quadruple stack motif, even at low concentrations, fully aggregated species prevail in nonpolar solvents, which enabled us to elucidate the photophysics of this supramolecular p/n-heterojunction in dilute solution by femtosecond time-resolved transient absorption spectroscopy. The observed photophysical processes include a favorably fast photoinduced electron transfer from the electron-donating dye stack to the electron-accepting fullerene moieties, a slower geminate charge carrier recombination of the generated electron and hole in the supramolecular p/n-heterojunction as well as the formation of fullerene triplet states. While the geminate recombination of charge carriers is supposed to be less competitive in BHJ photovoltaic materials due to the possibility of fast electron migration within fullerene domains in thin films, intersystem crossing into the triplet manifold appears as a more critical undesired process. These insights from spectroscopy may help to tailor improved photovoltaic materials, thereby demonstrating the value of fundamental studies on elementary photophysical processes in molecular aggregates.

  @article{Bialas_2022, abstract = {Supramolecular photosystems can afford important insights into elementary processes in molecular materials. Here, a bis(merocyanine)-C60 conjugate composed of two covalently tethered electron-donating merocyanine chromophores and two appended fullerene electron acceptor units is investigated. Concentration-dependent UV/Vis studies in nonpolar solvents revealed a bimolecular association (dimerization) process, resulting in the formation of an H-coupled merocyanine dye aggregate. The aggregate structure was confirmed by 2D NMR spectroscopy proving the presence of a well-defined quadruple dye stack surrounded by four loosely connected fullerenes, which mimics the donor–acceptor interface in bulk heterojunction (BHJ) solar cells. Due to the interdigitation of the dyes in the quadruple stack motif, even at low concentrations, fully aggregated species prevail in nonpolar solvents, which enabled us to elucidate the photophysics of this supramolecular p/n-heterojunction in dilute solution by femtosecond time-resolved transient absorption spectroscopy. The observed photophysical processes include a favorably fast photoinduced electron transfer from the electron-donating dye stack to the electron-accepting fullerene moieties, a slower geminate charge carrier recombination of the generated electron and hole in the supramolecular p/n-heterojunction as well as the formation of fullerene triplet states. While the geminate recombination of charge carriers is supposed to be less competitive in BHJ photovoltaic materials due to the possibility of fast electron migration within fullerene domains in thin films, intersystem crossing into the triplet manifold appears as a more critical undesired process. These insights from spectroscopy may help to tailor improved photovoltaic materials, thereby demonstrating the value of fundamental studies on elementary photophysical processes in molecular aggregates.}, author = {Bialas, David and Fennel, Franziska and Noll, Niklas and Holzapfel, Marco and Schmiedel, Alexander and Lambert, Christoph and Würthner, Frank}, journal = {Nat. Sci.}, keywords = {myown}, month = {03}, number = 2, publisher = {Wiley}, title = {Supramolecular p/n-heterojunction of C60-functionalized bis(merocyanine) quadruple stack: A model system for charge carrier separation and recombination in organic solar cells}, volume = 2, year = 2022 }

  %0 Journal Article %1 Bialas_2022 %A Bialas, David %A Fennel, Franziska %A Noll, Niklas %A Holzapfel, Marco %A Schmiedel, Alexander %A Lambert, Christoph %A Würthner, Frank %D 2022 %I Wiley %J Nat. Sci. %N 2 %R 10.1002/ntls.20210430 %T Supramolecular p/n-heterojunction of C60-functionalized bis(merocyanine) quadruple stack: A model system for charge carrier separation and recombination in organic solar cells %U https://doi.org/10.1002%2Fntls.20210430 %V 2 %X Supramolecular photosystems can afford important insights into elementary processes in molecular materials. Here, a bis(merocyanine)-C60 conjugate composed of two covalently tethered electron-donating merocyanine chromophores and two appended fullerene electron acceptor units is investigated. Concentration-dependent UV/Vis studies in nonpolar solvents revealed a bimolecular association (dimerization) process, resulting in the formation of an H-coupled merocyanine dye aggregate. The aggregate structure was confirmed by 2D NMR spectroscopy proving the presence of a well-defined quadruple dye stack surrounded by four loosely connected fullerenes, which mimics the donor–acceptor interface in bulk heterojunction (BHJ) solar cells. Due to the interdigitation of the dyes in the quadruple stack motif, even at low concentrations, fully aggregated species prevail in nonpolar solvents, which enabled us to elucidate the photophysics of this supramolecular p/n-heterojunction in dilute solution by femtosecond time-resolved transient absorption spectroscopy. The observed photophysical processes include a favorably fast photoinduced electron transfer from the electron-donating dye stack to the electron-accepting fullerene moieties, a slower geminate charge carrier recombination of the generated electron and hole in the supramolecular p/n-heterojunction as well as the formation of fullerene triplet states. While the geminate recombination of charge carriers is supposed to be less competitive in BHJ photovoltaic materials due to the possibility of fast electron migration within fullerene domains in thin films, intersystem crossing into the triplet manifold appears as a more critical undesired process. These insights from spectroscopy may help to tailor improved photovoltaic materials, thereby demonstrating the value of fundamental studies on elementary photophysical processes in molecular aggregates.
• Intramolecular Energy and Solvent-Dependent Chirality Transfer within a BINOL-Perylene Hetero-Cyclophane. Ouyang, Guanghui; Rühe, Jessica; Zhang, Yang; Lin, Mei-Jin; Liu, Minghua; Würthner, Frank. In Angew. Chem. Int. Ed., 61(31). 2022.
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  Multichromophoric macrocycles and cyclophanes are important supramolecular architectures for the elucidation of interchromophoric interactions originating from precise spatial organization. Herein, by combining an axially chiral binaphthol bisimide (BBI) and a bay-substituted conformationally labile twisted perylene bisimide (PBI) within a cyclophane of well-defined geometry, we report a chiral PBI hetero-cyclophane (BBI-PBI) that shows intramolecular energy and solvent-regulated chirality transfer from the BBI to the PBI subunit. Excellent spectral overlap and spatial arrangement of BBI and PBI lead to efficient excitation energy transfer and subsequent PBI emission with high quantum yield (80–98 %) in various solvents. In contrast, chirality transfer is strongly dependent on the respective solvent as revealed by circular dichroism (CD) spectroscopy. The combination of energy and chirality transfer affords a bright red circularly polarized luminescence (CPL) from the PBI chromophore by excitation of BBI.

  @article{Ouyang_2022, abstract = {Multichromophoric macrocycles and cyclophanes are important supramolecular architectures for the elucidation of interchromophoric interactions originating from precise spatial organization. Herein, by combining an axially chiral binaphthol bisimide (BBI) and a bay-substituted conformationally labile twisted perylene bisimide (PBI) within a cyclophane of well-defined geometry, we report a chiral PBI hetero-cyclophane (BBI-PBI) that shows intramolecular energy and solvent-regulated chirality transfer from the BBI to the PBI subunit. Excellent spectral overlap and spatial arrangement of BBI and PBI lead to efficient excitation energy transfer and subsequent PBI emission with high quantum yield (80–98 %) in various solvents. In contrast, chirality transfer is strongly dependent on the respective solvent as revealed by circular dichroism (CD) spectroscopy. The combination of energy and chirality transfer affords a bright red circularly polarized luminescence (CPL) from the PBI chromophore by excitation of BBI.}, author = {Ouyang, Guanghui and Rühe, Jessica and Zhang, Yang and Lin, Mei-Jin and Liu, Minghua and Würthner, Frank}, journal = {Angew. Chem. Int. Ed.}, keywords = {myown}, month = {06}, number = 31, publisher = {Wiley}, title = {Intramolecular Energy and Solvent-Dependent Chirality Transfer within a BINOL-Perylene Hetero-Cyclophane}, volume = 61, year = 2022 }

  %0 Journal Article %1 Ouyang_2022 %A Ouyang, Guanghui %A Rühe, Jessica %A Zhang, Yang %A Lin, Mei-Jin %A Liu, Minghua %A Würthner, Frank %D 2022 %I Wiley %J Angew. Chem. Int. Ed. %N 31 %R 10.1002/anie.202206706 %T Intramolecular Energy and Solvent-Dependent Chirality Transfer within a BINOL-Perylene Hetero-Cyclophane %U https://doi.org/10.1002%2Fanie.202206706 %V 61 %X Multichromophoric macrocycles and cyclophanes are important supramolecular architectures for the elucidation of interchromophoric interactions originating from precise spatial organization. Herein, by combining an axially chiral binaphthol bisimide (BBI) and a bay-substituted conformationally labile twisted perylene bisimide (PBI) within a cyclophane of well-defined geometry, we report a chiral PBI hetero-cyclophane (BBI-PBI) that shows intramolecular energy and solvent-regulated chirality transfer from the BBI to the PBI subunit. Excellent spectral overlap and spatial arrangement of BBI and PBI lead to efficient excitation energy transfer and subsequent PBI emission with high quantum yield (80–98 %) in various solvents. In contrast, chirality transfer is strongly dependent on the respective solvent as revealed by circular dichroism (CD) spectroscopy. The combination of energy and chirality transfer affords a bright red circularly polarized luminescence (CPL) from the PBI chromophore by excitation of BBI.
• Ultrafast Intersystem Crossing in Selenium-Annulated Perylene Bisimide. Sivanarayanan, Jibin; Sebastian, Ebin; Vinod, Kavya; Würthner, Frank; Hariharan, Mahesh. In J. Phys. Chem. C., 126(31), pp. 13319–13326. 2022.
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  An intersystem crossing (ISC), the non-radiative transition between two electronic states with different spin multiplicities, is ubiquitous and imperative in molecular photochemistry. The manifestation of a triplet manifold in π-conjugated chromophoric materials has a crucial role in enhancing the efficiency of photofunctional devices. Herein, we explore the triplet-state population in a series of chalcogen-annulated perylene bisimides (O-PBI, S-PBI, and Se-PBI), where the selenium-annulated PBI (Se-PBI) exhibits a near-quantitative triplet quantum yield ( = 94 ± 1%). Annulation of Se in the PBI core results in a drastic decrease in the fluorescence quantum yield ( = 1.5 ± 0.2%) compared to the bare PBI ( = 97.0 ± 1%), indicating the possibility of an efficient non-radiative decay pathway in the Se-PBI motif. Femtosecond and nanosecond transient absorption measurements unambiguously confirmed the ultrafast triplet population in Se-PBI with an ISC rate constant of = 2.39 × 1010 s–1 and the triplet-state decay to the ground state with a time constant of 3.78 μs. A theoretically calculated spin–orbit coupling constant (VSOC) of 122.4 cm–1 employing the SA-CASSCF/NEVPT2 method has rationalized the excited-state dynamics of Se-PBI. By virtue of the poor SOC between the singlet and triplet states, we observed a partial triplet population in S-PBI, whereas ISC is negligible in O-PBI. We demonstrate an increase in the spin–orbit coupling constant ( ≪ < ) and rate constant of ISC ( ≪ < ) across the series of chalcogen-annulated PBIs (O-PBI, S-PBI, and Se-PBI). The heavier chalcogenide PBI (Se-PBI) thus adds to the array of potential organic photoactive materials for the design of efficient solar energy conversion devices.

  @article{Sivanarayanan_2022, abstract = {An intersystem crossing (ISC), the non-radiative transition between two electronic states with different spin multiplicities, is ubiquitous and imperative in molecular photochemistry. The manifestation of a triplet manifold in π-conjugated chromophoric materials has a crucial role in enhancing the efficiency of photofunctional devices. Herein, we explore the triplet-state population in a series of chalcogen-annulated perylene bisimides (O-PBI, S-PBI, and Se-PBI), where the selenium-annulated PBI (Se-PBI) exhibits a near-quantitative triplet quantum yield ( = 94 ± 1%). Annulation of Se in the PBI core results in a drastic decrease in the fluorescence quantum yield ( = 1.5 ± 0.2%) compared to the bare PBI ( = 97.0 ± 1%), indicating the possibility of an efficient non-radiative decay pathway in the Se-PBI motif. Femtosecond and nanosecond transient absorption measurements unambiguously confirmed the ultrafast triplet population in Se-PBI with an ISC rate constant of = 2.39 × 1010 s–1 and the triplet-state decay to the ground state with a time constant of 3.78 μs. A theoretically calculated spin–orbit coupling constant (VSOC) of 122.4 cm–1 employing the SA-CASSCF/NEVPT2 method has rationalized the excited-state dynamics of Se-PBI. By virtue of the poor SOC between the singlet and triplet states, we observed a partial triplet population in S-PBI, whereas ISC is negligible in O-PBI. We demonstrate an increase in the spin–orbit coupling constant ( ≪ < ) and rate constant of ISC ( ≪ < ) across the series of chalcogen-annulated PBIs (O-PBI, S-PBI, and Se-PBI). The heavier chalcogenide PBI (Se-PBI) thus adds to the array of potential organic photoactive materials for the design of efficient solar energy conversion devices.}, author = {Sivanarayanan, Jibin and Sebastian, Ebin and Vinod, Kavya and Würthner, Frank and Hariharan, Mahesh}, journal = {J. Phys. Chem. C.}, keywords = {myown}, month = {07}, number = 31, pages = {13319–13326}, publisher = {American Chemical Society (ACS)}, title = {Ultrafast Intersystem Crossing in Selenium-Annulated Perylene Bisimide}, volume = 126, year = 2022 }

  %0 Journal Article %1 Sivanarayanan_2022 %A Sivanarayanan, Jibin %A Sebastian, Ebin %A Vinod, Kavya %A Würthner, Frank %A Hariharan, Mahesh %D 2022 %I American Chemical Society (ACS) %J J. Phys. Chem. C. %N 31 %P 13319--13326 %R 10.1021/acs.jpcc.2c03847 %T Ultrafast Intersystem Crossing in Selenium-Annulated Perylene Bisimide %U https://doi.org/10.1021%2Facs.jpcc.2c03847 %V 126 %X An intersystem crossing (ISC), the non-radiative transition between two electronic states with different spin multiplicities, is ubiquitous and imperative in molecular photochemistry. The manifestation of a triplet manifold in π-conjugated chromophoric materials has a crucial role in enhancing the efficiency of photofunctional devices. Herein, we explore the triplet-state population in a series of chalcogen-annulated perylene bisimides (O-PBI, S-PBI, and Se-PBI), where the selenium-annulated PBI (Se-PBI) exhibits a near-quantitative triplet quantum yield ( = 94 ± 1%). Annulation of Se in the PBI core results in a drastic decrease in the fluorescence quantum yield ( = 1.5 ± 0.2%) compared to the bare PBI ( = 97.0 ± 1%), indicating the possibility of an efficient non-radiative decay pathway in the Se-PBI motif. Femtosecond and nanosecond transient absorption measurements unambiguously confirmed the ultrafast triplet population in Se-PBI with an ISC rate constant of = 2.39 × 1010 s–1 and the triplet-state decay to the ground state with a time constant of 3.78 μs. A theoretically calculated spin–orbit coupling constant (VSOC) of 122.4 cm–1 employing the SA-CASSCF/NEVPT2 method has rationalized the excited-state dynamics of Se-PBI. By virtue of the poor SOC between the singlet and triplet states, we observed a partial triplet population in S-PBI, whereas ISC is negligible in O-PBI. We demonstrate an increase in the spin–orbit coupling constant ( ≪ < ) and rate constant of ISC ( ≪ < ) across the series of chalcogen-annulated PBIs (O-PBI, S-PBI, and Se-PBI). The heavier chalcogenide PBI (Se-PBI) thus adds to the array of potential organic photoactive materials for the design of efficient solar energy conversion devices.
• Phenol-Functionalized Perylene Bisimides as Amine-Free Electron Transporting Interlayers for Stable Nonfullerene Organic Solar Cells. Wen, Xinbo; Zhang, Yu; Xie, Guojing; Rausch, Rodger; Tang, Ningning; Zheng, Nan; Liu, Linlin; Würthner, Frank; Xie, Zengqi. In Adv. Funct. Mater., 32(17), p. 2111706. 2022.
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  A new type of cathode interlayer composed of 2,6-di-tert-butyl-phenol-functionalized perylene bisimide (PBI-2P) is successfully applied as an electron transporting layer for fused-ring nonfullerene organic solar cells (OSCs). The stable contact between these novel electron transporting layers and the representative nonfullerene acceptor Y6 greatly enhances the device stability compared to conventional amine-group containing cathode interlayers. Moreover, the easily formed biradical species in the interlayers yields rather good thickness tolerance of the PBI-2P layer in photovoltaic devices. The OSCs based on the PBI-2P interlayer show a power conversion efficiency up to 17.20% and good stability compared to amino-group functionalized interlayers. The findings demonstrate a promising design principle for cathode interlayer engineering based on pigment chromophores equipped with the 2,6-di-tert-butylphenoxy groups that are prone to form the respective ultrastable butylphenoxy radicals for stable nonfullerene OSCs.

  @article{Wen_2022, abstract = {A new type of cathode interlayer composed of 2,6-di-tert-butyl-phenol-functionalized perylene bisimide (PBI-2P) is successfully applied as an electron transporting layer for fused-ring nonfullerene organic solar cells (OSCs). The stable contact between these novel electron transporting layers and the representative nonfullerene acceptor Y6 greatly enhances the device stability compared to conventional amine-group containing cathode interlayers. Moreover, the easily formed biradical species in the interlayers yields rather good thickness tolerance of the PBI-2P layer in photovoltaic devices. The OSCs based on the PBI-2P interlayer show a power conversion efficiency up to 17.20% and good stability compared to amino-group functionalized interlayers. The findings demonstrate a promising design principle for cathode interlayer engineering based on pigment chromophores equipped with the 2,6-di-tert-butylphenoxy groups that are prone to form the respective ultrastable butylphenoxy radicals for stable nonfullerene OSCs.}, author = {Wen, Xinbo and Zhang, Yu and Xie, Guojing and Rausch, Rodger and Tang, Ningning and Zheng, Nan and Liu, Linlin and Würthner, Frank and Xie, Zengqi}, journal = {Adv. Funct. Mater.}, keywords = {myown}, month = {01}, number = 17, pages = 2111706, publisher = {Wiley}, title = {Phenol-Functionalized Perylene Bisimides as Amine-Free Electron Transporting Interlayers for Stable Nonfullerene Organic Solar Cells}, volume = 32, year = 2022 }

  %0 Journal Article %1 Wen_2022 %A Wen, Xinbo %A Zhang, Yu %A Xie, Guojing %A Rausch, Rodger %A Tang, Ningning %A Zheng, Nan %A Liu, Linlin %A Würthner, Frank %A Xie, Zengqi %D 2022 %I Wiley %J Adv. Funct. Mater. %N 17 %P 2111706 %R 10.1002/adfm.202111706 %T Phenol-Functionalized Perylene Bisimides as Amine-Free Electron Transporting Interlayers for Stable Nonfullerene Organic Solar Cells %U https://doi.org/10.1002%2Fadfm.202111706 %V 32 %X A new type of cathode interlayer composed of 2,6-di-tert-butyl-phenol-functionalized perylene bisimide (PBI-2P) is successfully applied as an electron transporting layer for fused-ring nonfullerene organic solar cells (OSCs). The stable contact between these novel electron transporting layers and the representative nonfullerene acceptor Y6 greatly enhances the device stability compared to conventional amine-group containing cathode interlayers. Moreover, the easily formed biradical species in the interlayers yields rather good thickness tolerance of the PBI-2P layer in photovoltaic devices. The OSCs based on the PBI-2P interlayer show a power conversion efficiency up to 17.20% and good stability compared to amino-group functionalized interlayers. The findings demonstrate a promising design principle for cathode interlayer engineering based on pigment chromophores equipped with the 2,6-di-tert-butylphenoxy groups that are prone to form the respective ultrastable butylphenoxy radicals for stable nonfullerene OSCs.
• Photon-Correlation Studies on Multichromophore Macrocycles of Perylene Dyes. Müller, Ulrich; Spenst, Peter; Kagerer, Philipp; Stolte, Matthias; Würthner, Frank; Pflaum, Jens. In Adv. Opt. Mater., 10(14), p. 2200234. 2022.
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  Organic dyes offer unique properties for their application as room temperature single photon emitters. By means of photon-correlation, the emission characteristics of macrocyclic para-xylylene linked perylene bisimide (PBI) trimers and tetramers dispersed in polymethyl methacrylate matrices are analyzed. The optical data indicate that, despite of the strong emission enhancement of PBI trimers and tetramers according to their larger number of chromophores, the photon-correlation statistics still obeys that of single photon emitters. Moreover, driving PBI trimers and tetramers at higher excitation powers, saturated emission behavior for monomers is found while macrocycle emission is still far-off saturation but shows enhanced fluctuations. This observation is attributed to fast singlet–singlet annihilation, i.e., faster than the radiative lifetime of the excited S1 state, and the enlarged number of conformational arrangements of multichromophores in the polymeric host. Finally, embedding trimeric PBI macrocycles in active organic light-emitting diode matrices, electrically driven bright fluorescence together with an indication for antibunching at room temperature can be detected. This, so far, has only been observed for phosphorescent emitters that feature much longer lifetimes of the excited states and, thus, smaller radiative recombination rates. The results are discussed in the context of possible effects on the g(2) behavior of molecular emitters.

  @article{M_ller_2022, abstract = {Organic dyes offer unique properties for their application as room temperature single photon emitters. By means of photon-correlation, the emission characteristics of macrocyclic para-xylylene linked perylene bisimide (PBI) trimers and tetramers dispersed in polymethyl methacrylate matrices are analyzed. The optical data indicate that, despite of the strong emission enhancement of PBI trimers and tetramers according to their larger number of chromophores, the photon-correlation statistics still obeys that of single photon emitters. Moreover, driving PBI trimers and tetramers at higher excitation powers, saturated emission behavior for monomers is found while macrocycle emission is still far-off saturation but shows enhanced fluctuations. This observation is attributed to fast singlet–singlet annihilation, i.e., faster than the radiative lifetime of the excited S1 state, and the enlarged number of conformational arrangements of multichromophores in the polymeric host. Finally, embedding trimeric PBI macrocycles in active organic light-emitting diode matrices, electrically driven bright fluorescence together with an indication for antibunching at room temperature can be detected. This, so far, has only been observed for phosphorescent emitters that feature much longer lifetimes of the excited states and, thus, smaller radiative recombination rates. The results are discussed in the context of possible effects on the g(2) behavior of molecular emitters.}, author = {Müller, Ulrich and Spenst, Peter and Kagerer, Philipp and Stolte, Matthias and Würthner, Frank and Pflaum, Jens}, journal = {Adv. Opt. Mater.}, keywords = {myown}, month = {05}, number = 14, pages = 2200234, publisher = {Wiley}, title = {Photon-Correlation Studies on Multichromophore Macrocycles of Perylene Dyes}, volume = 10, year = 2022 }

  %0 Journal Article %1 M_ller_2022 %A Müller, Ulrich %A Spenst, Peter %A Kagerer, Philipp %A Stolte, Matthias %A Würthner, Frank %A Pflaum, Jens %D 2022 %I Wiley %J Adv. Opt. Mater. %N 14 %P 2200234 %R 10.1002/adom.202200234 %T Photon-Correlation Studies on Multichromophore Macrocycles of Perylene Dyes %U https://doi.org/10.1002%2Fadom.202200234 %V 10 %X Organic dyes offer unique properties for their application as room temperature single photon emitters. By means of photon-correlation, the emission characteristics of macrocyclic para-xylylene linked perylene bisimide (PBI) trimers and tetramers dispersed in polymethyl methacrylate matrices are analyzed. The optical data indicate that, despite of the strong emission enhancement of PBI trimers and tetramers according to their larger number of chromophores, the photon-correlation statistics still obeys that of single photon emitters. Moreover, driving PBI trimers and tetramers at higher excitation powers, saturated emission behavior for monomers is found while macrocycle emission is still far-off saturation but shows enhanced fluctuations. This observation is attributed to fast singlet–singlet annihilation, i.e., faster than the radiative lifetime of the excited S1 state, and the enlarged number of conformational arrangements of multichromophores in the polymeric host. Finally, embedding trimeric PBI macrocycles in active organic light-emitting diode matrices, electrically driven bright fluorescence together with an indication for antibunching at room temperature can be detected. This, so far, has only been observed for phosphorescent emitters that feature much longer lifetimes of the excited states and, thus, smaller radiative recombination rates. The results are discussed in the context of possible effects on the g(2) behavior of molecular emitters.
• Aggregation-Induced Dual Phosphorescence from (o-Bromophenyl)-Bis(2,6-Dimethylphenyl)Borane at Room Temperature. Wu, Zhu; Dinkelbach, Fabian; Kerner, Florian; Friedrich, Alexandra; Ji, Lei; Stepanenko, Vladimir; Würthner, Frank; Marian, Christel M.; Marder, Todd B. In Chem. Eur. J., 28(30). 2022.
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  Designing highly efficient purely organic phosphors at room temperature remains a challenge because of fast non-radiative processes and slow intersystem crossing (ISC) rates. The majority of them emit only single component phosphorescence. Herein, we have prepared 3 isomers (o, m, p-bromophenyl)-bis(2,6-dimethylphenyl)boranes. Among the 3 isomers (o-, m- and p-BrTAB) synthesized, the ortho-one is the only one which shows dual phosphorescence, with a short lifetime of 0.8 ms and a long lifetime of 234 ms in the crystalline state at room temperature. Based on theoretical calculations and crystal structure analysis of o-BrTAB, the short lifetime component is ascribed to the T1M state of the monomer which emits the higher energy phosphorescence. The long-lived, lower energy phosphorescence emission is attributed to the T1A state of an aggregate, with multiple intermolecular interactions existing in crystalline o-BrTAB inhibiting nonradiative decay and stabilizing the triplet states efficiently.

  @article{Wu_2022, abstract = {Designing highly efficient purely organic phosphors at room temperature remains a challenge because of fast non-radiative processes and slow intersystem crossing (ISC) rates. The majority of them emit only single component phosphorescence. Herein, we have prepared 3 isomers (o, m, p-bromophenyl)-bis(2,6-dimethylphenyl)boranes. Among the 3 isomers (o-, m- and p-BrTAB) synthesized, the ortho-one is the only one which shows dual phosphorescence, with a short lifetime of 0.8 ms and a long lifetime of 234 ms in the crystalline state at room temperature. Based on theoretical calculations and crystal structure analysis of o-BrTAB, the short lifetime component is ascribed to the T1M state of the monomer which emits the higher energy phosphorescence. The long-lived, lower energy phosphorescence emission is attributed to the T1A state of an aggregate, with multiple intermolecular interactions existing in crystalline o-BrTAB inhibiting nonradiative decay and stabilizing the triplet states efficiently.}, author = {Wu, Zhu and Dinkelbach, Fabian and Kerner, Florian and Friedrich, Alexandra and Ji, Lei and Stepanenko, Vladimir and Würthner, Frank and Marian, Christel M. and Marder, Todd B.}, journal = {Chem. Eur. J.}, keywords = {myown}, month = {04}, number = 30, publisher = {Wiley}, title = {Aggregation-Induced Dual Phosphorescence from (o-Bromophenyl)-Bis(2,6-Dimethylphenyl)Borane at Room Temperature}, volume = 28, year = 2022 }

  %0 Journal Article %1 Wu_2022 %A Wu, Zhu %A Dinkelbach, Fabian %A Kerner, Florian %A Friedrich, Alexandra %A Ji, Lei %A Stepanenko, Vladimir %A Würthner, Frank %A Marian, Christel M. %A Marder, Todd B. %D 2022 %I Wiley %J Chem. Eur. J. %N 30 %R 10.1002/chem.202200525 %T Aggregation-Induced Dual Phosphorescence from (o-Bromophenyl)-Bis(2,6-Dimethylphenyl)Borane at Room Temperature %U https://doi.org/10.1002%2Fchem.202200525 %V 28 %X Designing highly efficient purely organic phosphors at room temperature remains a challenge because of fast non-radiative processes and slow intersystem crossing (ISC) rates. The majority of them emit only single component phosphorescence. Herein, we have prepared 3 isomers (o, m, p-bromophenyl)-bis(2,6-dimethylphenyl)boranes. Among the 3 isomers (o-, m- and p-BrTAB) synthesized, the ortho-one is the only one which shows dual phosphorescence, with a short lifetime of 0.8 ms and a long lifetime of 234 ms in the crystalline state at room temperature. Based on theoretical calculations and crystal structure analysis of o-BrTAB, the short lifetime component is ascribed to the T1M state of the monomer which emits the higher energy phosphorescence. The long-lived, lower energy phosphorescence emission is attributed to the T1A state of an aggregate, with multiple intermolecular interactions existing in crystalline o-BrTAB inhibiting nonradiative decay and stabilizing the triplet states efficiently.
• Real-time Observation of Structural Dynamics Triggering Excimer Formation in a Perylene Bisimide Folda-dimer by Ultrafast Time-Domain Raman Spectroscopy. Hong, Yongseok; Kim, Woojae; Kim, Taeyeon; Kaufmann, Christina; Kim, Hyungjun; Würthner, Frank; Kim, Dongho. In Angew. Chem. Int. Ed., 61(13). 2022.
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  In π-conjugated organic photovoltaic materials, an excimer state has been generally regarded as a trap state which hinders efficient excitation energy transport. But despite wide investigations of the excimer for overcoming the undesirable energy loss, the understanding of the relationship between the structure of the excimer in stacked organic compounds and its properties remains elusive. Here, we present the landscape of structural dynamics from the excimer formation to its relaxation in a co-facially stacked archetypical perylene bisimide folda-dimer using ultrafast time-domain Raman spectroscopy. We directly captured vibrational snapshots illustrating the ultrafast structural evolution triggering the excimer formation along the interchromophore coordinate on the complex excited-state potential surfaces and following evolution into a relaxed excimer state. Not only does this work showcase the ultrafast structural dynamics necessary for the excimer formation and control of excimer characteristics but also provides important criteria for designing the π-conjugated organic molecules.

  @article{Hong_2022, abstract = {In π-conjugated organic photovoltaic materials, an excimer state has been generally regarded as a trap state which hinders efficient excitation energy transport. But despite wide investigations of the excimer for overcoming the undesirable energy loss, the understanding of the relationship between the structure of the excimer in stacked organic compounds and its properties remains elusive. Here, we present the landscape of structural dynamics from the excimer formation to its relaxation in a co-facially stacked archetypical perylene bisimide folda-dimer using ultrafast time-domain Raman spectroscopy. We directly captured vibrational snapshots illustrating the ultrafast structural evolution triggering the excimer formation along the interchromophore coordinate on the complex excited-state potential surfaces and following evolution into a relaxed excimer state. Not only does this work showcase the ultrafast structural dynamics necessary for the excimer formation and control of excimer characteristics but also provides important criteria for designing the π-conjugated organic molecules.}, author = {Hong, Yongseok and Kim, Woojae and Kim, Taeyeon and Kaufmann, Christina and Kim, Hyungjun and Würthner, Frank and Kim, Dongho}, journal = {Angew. Chem. Int. Ed.}, keywords = {myown}, month = {02}, number = 13, publisher = {Wiley}, title = {Real-time Observation of Structural Dynamics Triggering Excimer Formation in a Perylene Bisimide Folda-dimer by Ultrafast Time-Domain Raman Spectroscopy}, volume = 61, year = 2022 }

  %0 Journal Article %1 Hong_2022 %A Hong, Yongseok %A Kim, Woojae %A Kim, Taeyeon %A Kaufmann, Christina %A Kim, Hyungjun %A Würthner, Frank %A Kim, Dongho %D 2022 %I Wiley %J Angew. Chem. Int. Ed. %N 13 %R 10.1002/anie.202114474 %T Real-time Observation of Structural Dynamics Triggering Excimer Formation in a Perylene Bisimide Folda-dimer by Ultrafast Time-Domain Raman Spectroscopy %U https://doi.org/10.1002%2Fanie.202114474 %V 61 %X In π-conjugated organic photovoltaic materials, an excimer state has been generally regarded as a trap state which hinders efficient excitation energy transport. But despite wide investigations of the excimer for overcoming the undesirable energy loss, the understanding of the relationship between the structure of the excimer in stacked organic compounds and its properties remains elusive. Here, we present the landscape of structural dynamics from the excimer formation to its relaxation in a co-facially stacked archetypical perylene bisimide folda-dimer using ultrafast time-domain Raman spectroscopy. We directly captured vibrational snapshots illustrating the ultrafast structural evolution triggering the excimer formation along the interchromophore coordinate on the complex excited-state potential surfaces and following evolution into a relaxed excimer state. Not only does this work showcase the ultrafast structural dynamics necessary for the excimer formation and control of excimer characteristics but also provides important criteria for designing the π-conjugated organic molecules.
• Boron-Locked Starazine - A Soluble and Fluorescent Analogue of Starphene. Feng, Yi; Zhou, Jiadong; Qiu, Honglin; Schnitzlein, Matthias; Hu, Jingtao; Liu, Linlin; Würthner, Frank; Xie, Zengqi. In Chem. Eur. J., 28(29). 2022.
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  A starlike heterocyclic molecule containing an electron-deficient nonaaza-core structure and three peripheral isoquinolines locked by three tetracoordinate borons, namely isoquinoline-nona-starazine (QNSA), is synthesized by using readily available reactants through a rather straightforward approach. This new heteroatom-rich QNSA possesses a quasi-planar π-backbone structure, and bears phenyl substituents on borons which protrude on both sides of the π-backbones endowing it with good solubility in common organic solvents. Contrasting to its starphene analogue, QNSA shows intense fluorescence with a quantum yield (PLQY) of up to 62 % in dilute solution.

  @article{Feng_2022, abstract = {A starlike heterocyclic molecule containing an electron-deficient nonaaza-core structure and three peripheral isoquinolines locked by three tetracoordinate borons, namely isoquinoline-nona-starazine (QNSA), is synthesized by using readily available reactants through a rather straightforward approach. This new heteroatom-rich QNSA possesses a quasi-planar π-backbone structure, and bears phenyl substituents on borons which protrude on both sides of the π-backbones endowing it with good solubility in common organic solvents. Contrasting to its starphene analogue, QNSA shows intense fluorescence with a quantum yield (PLQY) of up to 62 % in dilute solution.}, author = {Feng, Yi and Zhou, Jiadong and Qiu, Honglin and Schnitzlein, Matthias and Hu, Jingtao and Liu, Linlin and Würthner, Frank and Xie, Zengqi}, journal = {Chem. Eur. J.}, keywords = {myown}, month = {04}, number = 29, publisher = {Wiley}, title = {Boron-Locked Starazine - A Soluble and Fluorescent Analogue of Starphene}, volume = 28, year = 2022 }

  %0 Journal Article %1 Feng_2022 %A Feng, Yi %A Zhou, Jiadong %A Qiu, Honglin %A Schnitzlein, Matthias %A Hu, Jingtao %A Liu, Linlin %A Würthner, Frank %A Xie, Zengqi %D 2022 %I Wiley %J Chem. Eur. J. %N 29 %R 10.1002/chem.202200770 %T Boron-Locked Starazine - A Soluble and Fluorescent Analogue of Starphene %U https://doi.org/10.1002%2Fchem.202200770 %V 28 %X A starlike heterocyclic molecule containing an electron-deficient nonaaza-core structure and three peripheral isoquinolines locked by three tetracoordinate borons, namely isoquinoline-nona-starazine (QNSA), is synthesized by using readily available reactants through a rather straightforward approach. This new heteroatom-rich QNSA possesses a quasi-planar π-backbone structure, and bears phenyl substituents on borons which protrude on both sides of the π-backbones endowing it with good solubility in common organic solvents. Contrasting to its starphene analogue, QNSA shows intense fluorescence with a quantum yield (PLQY) of up to 62 % in dilute solution.
• Multilayer stacks of polycyclic aromatic hydrocarbons. Mahl, Magnus; Niyas, M. A.; Shoyama, Kazutaka; Würthner, Frank. In Nature Chemistry, 14(4), pp. 457–462. 2022.
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  Polycyclic aromatic hydrocarbons (PAHs) show promise for applications in functional devices such as organic photovoltaics and field-effect transistors, but, although nanometre-sized PAHs—often referred to as nanographenes—have been well inves- tigated as single-layer molecules, their multilayer counterparts remain rather unexplored. Here we show the assembly of a C64 nanographene derivative (comprising a planar core decorated with four meta-terphenyl–imide moieties at its periphery) into multilayer stacks with smaller PAHs ranging from naphthalene to ovalene and hexabenzocoronene. The functionalized C64 nanographene serves as a ditopic host that can accommodate a smaller PAH on either side of its planar core, in cavities delim- ited by its bulky imide substituents. Bilayers and trilayers (that is, complexes with 1:1 and 1:2 host:guest ratios, respectively) were observed in solution, and dimers of these complexes as well as multilayer compounds were isolated in the solid state. Quantum-chemical calculations indicate that dispersion forces are the main stabilizing factor for these complexes.

  @article{Mahl_2022, abstract = {Polycyclic aromatic hydrocarbons (PAHs) show promise for applications in functional devices such as organic photovoltaics and field-effect transistors, but, although nanometre-sized PAHs—often referred to as nanographenes—have been well inves- tigated as single-layer molecules, their multilayer counterparts remain rather unexplored. Here we show the assembly of a C64 nanographene derivative (comprising a planar core decorated with four meta-terphenyl–imide moieties at its periphery) into multilayer stacks with smaller PAHs ranging from naphthalene to ovalene and hexabenzocoronene. The functionalized C64 nanographene serves as a ditopic host that can accommodate a smaller PAH on either side of its planar core, in cavities delim- ited by its bulky imide substituents. Bilayers and trilayers (that is, complexes with 1:1 and 1:2 host:guest ratios, respectively) were observed in solution, and dimers of these complexes as well as multilayer compounds were isolated in the solid state. Quantum-chemical calculations indicate that dispersion forces are the main stabilizing factor for these complexes.}, author = {Mahl, Magnus and Niyas, M. A. and Shoyama, Kazutaka and Würthner, Frank}, journal = {Nature Chemistry}, keywords = {myown}, month = {02}, number = 4, pages = {457–462}, publisher = {Springer Science and Business Media {LLC}}, title = {Multilayer stacks of polycyclic aromatic hydrocarbons}, volume = 14, year = 2022 }

  %0 Journal Article %1 Mahl_2022 %A Mahl, Magnus %A Niyas, M. A. %A Shoyama, Kazutaka %A Würthner, Frank %D 2022 %I Springer Science and Business Media LLC %J Nature Chemistry %N 4 %P 457--462 %R 10.1038/s41557-021-00861-5 %T Multilayer stacks of polycyclic aromatic hydrocarbons %U https://doi.org/10.1038%2Fs41557-021-00861-5 %V 14 %X Polycyclic aromatic hydrocarbons (PAHs) show promise for applications in functional devices such as organic photovoltaics and field-effect transistors, but, although nanometre-sized PAHs—often referred to as nanographenes—have been well inves- tigated as single-layer molecules, their multilayer counterparts remain rather unexplored. Here we show the assembly of a C64 nanographene derivative (comprising a planar core decorated with four meta-terphenyl–imide moieties at its periphery) into multilayer stacks with smaller PAHs ranging from naphthalene to ovalene and hexabenzocoronene. The functionalized C64 nanographene serves as a ditopic host that can accommodate a smaller PAH on either side of its planar core, in cavities delim- ited by its bulky imide substituents. Bilayers and trilayers (that is, complexes with 1:1 and 1:2 host:guest ratios, respectively) were observed in solution, and dimers of these complexes as well as multilayer compounds were isolated in the solid state. Quantum-chemical calculations indicate that dispersion forces are the main stabilizing factor for these complexes.
• Helically Twisted Nanoribbons Based on Emissive Near-Infrared Responsive Quaterrylene Bisimides. Mahlmeister, Bernhard; Mahl, Magnus; Reichelt, Helmut; Shoyama, Kazutaka; Stolte, Matthias; Würthner, Frank. In J. Am. Chem. Soc., 144(23), pp. 10507–10514. 2022.
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  Graphene nanoribbons (GNRs) have the potential for next-generation functional devices. So far, GNRs with defined stereochemistry are rarely reported in literature and their optical response is usually bound to the ultraviolet or visible spectral region, while covering the near-infrared (NIR) regime is still challenging. Herein, we report two novel quaterrylene bisimides with either one- or twofold-twisted π-backbones enabled by the steric congestion of a fourfold bay arylation leading to an end-to-end twist of up to 76°. The strong interlocking effect of the π-stacked aryl substituents introduces a rigidification of the chromophore unambiguously proven by single-crystal X-ray analysis. This leads to unexpectedly strong NIR emissions at 862 and 903 nm with quantum yields of 1.5 and 0.9%, respectively, further ensuring high solubility as well as resolvable and highly stable atropo-enantiomers. Circular dichroism spectroscopy of these enantiopure chiral compounds reveals a strong Cotton effect Δε of up to 67 M–1 cm–1 centered far in the NIR region at 849 nm.

  @article{Mahlmeister_2022, abstract = {Graphene nanoribbons (GNRs) have the potential for next-generation functional devices. So far, GNRs with defined stereochemistry are rarely reported in literature and their optical response is usually bound to the ultraviolet or visible spectral region, while covering the near-infrared (NIR) regime is still challenging. Herein, we report two novel quaterrylene bisimides with either one- or twofold-twisted π-backbones enabled by the steric congestion of a fourfold bay arylation leading to an end-to-end twist of up to 76°. The strong interlocking effect of the π-stacked aryl substituents introduces a rigidification of the chromophore unambiguously proven by single-crystal X-ray analysis. This leads to unexpectedly strong NIR emissions at 862 and 903 nm with quantum yields of 1.5 and 0.9%, respectively, further ensuring high solubility as well as resolvable and highly stable atropo-enantiomers. Circular dichroism spectroscopy of these enantiopure chiral compounds reveals a strong Cotton effect Δε of up to 67 M–1 cm–1 centered far in the NIR region at 849 nm.}, author = {Mahlmeister, Bernhard and Mahl, Magnus and Reichelt, Helmut and Shoyama, Kazutaka and Stolte, Matthias and Würthner, Frank}, journal = {J. Am. Chem. Soc.}, keywords = {myown}, month = {06}, number = 23, pages = {10507–10514}, publisher = {American Chemical Society (ACS)}, title = {Helically Twisted Nanoribbons Based on Emissive Near-Infrared Responsive Quaterrylene Bisimides}, volume = 144, year = 2022 }

  %0 Journal Article %1 Mahlmeister_2022 %A Mahlmeister, Bernhard %A Mahl, Magnus %A Reichelt, Helmut %A Shoyama, Kazutaka %A Stolte, Matthias %A Würthner, Frank %D 2022 %I American Chemical Society (ACS) %J J. Am. Chem. Soc. %N 23 %P 10507--10514 %R 10.1021/jacs.2c02947 %T Helically Twisted Nanoribbons Based on Emissive Near-Infrared Responsive Quaterrylene Bisimides %U https://doi.org/10.1021%2Fjacs.2c02947 %V 144 %X Graphene nanoribbons (GNRs) have the potential for next-generation functional devices. So far, GNRs with defined stereochemistry are rarely reported in literature and their optical response is usually bound to the ultraviolet or visible spectral region, while covering the near-infrared (NIR) regime is still challenging. Herein, we report two novel quaterrylene bisimides with either one- or twofold-twisted π-backbones enabled by the steric congestion of a fourfold bay arylation leading to an end-to-end twist of up to 76°. The strong interlocking effect of the π-stacked aryl substituents introduces a rigidification of the chromophore unambiguously proven by single-crystal X-ray analysis. This leads to unexpectedly strong NIR emissions at 862 and 903 nm with quantum yields of 1.5 and 0.9%, respectively, further ensuring high solubility as well as resolvable and highly stable atropo-enantiomers. Circular dichroism spectroscopy of these enantiopure chiral compounds reveals a strong Cotton effect Δε of up to 67 M–1 cm–1 centered far in the NIR region at 849 nm.
• 12b,24b-Diborahexabenzo[a,c,fg,l,n,qr]pentacene: A Low-LUMO Boron-Doped Polycyclic Aromatic Hydrocarbon. Mützel, Carina; Farrell, Jeffrey M.; Shoyama, Kazutaka; Würthner, Frank. In Angew. Chem. Int. Ed., 61(8). 2022.
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  Herein we devise and execute a new synthesis of a pristine boron-doped nanographene. Our target boron-doped nanographene was designed based on DFT calculations to possess a low LUMO energy level and a narrow band gap derived from its precise geometry and B-doping arrangement. Our synthesis of this target, a doubly B-doped hexabenzopentacene (B2-HBP), employs six net C H borylations of an alkene, comprising consecutive hydroboration/electrophilic borylation/dehydrogenation and BBr3/AlCl3/2,6-dichloropyridine- mediated C H borylation steps. As predicted by our calculations, B2-HBP absorbs strongly in the visible region and emits in the NIR up to 1150 nm in o-dichlorobenzene solutions. Furthermore, B2-HBP possesses a very low LUMO level, showing two reversible reductions at 1.00 V and 1.17 V vs. Fc+/Fc. Our methodology is surprisingly selective despite its implementation of unfunctionalized precursors and offers a new approach to the synthesis of pristine B-doped polycyclic aromatic hydrocarbons.

  @article{Muetzel_2022, abstract = {Herein we devise and execute a new synthesis of a pristine boron-doped nanographene. Our target boron-doped nanographene was designed based on DFT calculations to possess a low LUMO energy level and a narrow band gap derived from its precise geometry and B-doping arrangement. Our synthesis of this target, a doubly B-doped hexabenzopentacene (B2-HBP), employs six net C H borylations of an alkene, comprising consecutive hydroboration/electrophilic borylation/dehydrogenation and BBr3/AlCl3/2,6-dichloropyridine- mediated C H borylation steps. As predicted by our calculations, B2-HBP absorbs strongly in the visible region and emits in the NIR up to 1150 nm in o-dichlorobenzene solutions. Furthermore, B2-HBP possesses a very low LUMO level, showing two reversible reductions at 1.00 V and 1.17 V vs. Fc+/Fc. Our methodology is surprisingly selective despite its implementation of unfunctionalized precursors and offers a new approach to the synthesis of pristine B-doped polycyclic aromatic hydrocarbons.}, author = {Mützel, Carina and Farrell, Jeffrey M. and Shoyama, Kazutaka and Würthner, Frank}, journal = {Angew. Chem. Int. Ed.}, keywords = {myown}, month = {01}, number = 8, publisher = {Wiley}, title = {12b,24b-Diborahexabenzo[a,c,fg,l,n,qr]pentacene: A Low-LUMO Boron-Doped Polycyclic Aromatic Hydrocarbon}, volume = 61, year = 2022 }

  %0 Journal Article %1 Muetzel_2022 %A Mützel, Carina %A Farrell, Jeffrey M. %A Shoyama, Kazutaka %A Würthner, Frank %D 2022 %I Wiley %J Angew. Chem. Int. Ed. %N 8 %R 10.1002/anie.202115746 %T 12b,24b-Diborahexabenzo[a,c,fg,l,n,qr]pentacene: A Low-LUMO Boron-Doped Polycyclic Aromatic Hydrocarbon %U https://doi.org/10.1002%2Fanie.202115746 %V 61 %X Herein we devise and execute a new synthesis of a pristine boron-doped nanographene. Our target boron-doped nanographene was designed based on DFT calculations to possess a low LUMO energy level and a narrow band gap derived from its precise geometry and B-doping arrangement. Our synthesis of this target, a doubly B-doped hexabenzopentacene (B2-HBP), employs six net C H borylations of an alkene, comprising consecutive hydroboration/electrophilic borylation/dehydrogenation and BBr3/AlCl3/2,6-dichloropyridine- mediated C H borylation steps. As predicted by our calculations, B2-HBP absorbs strongly in the visible region and emits in the NIR up to 1150 nm in o-dichlorobenzene solutions. Furthermore, B2-HBP possesses a very low LUMO level, showing two reversible reductions at 1.00 V and 1.17 V vs. Fc+/Fc. Our methodology is surprisingly selective despite its implementation of unfunctionalized precursors and offers a new approach to the synthesis of pristine B-doped polycyclic aromatic hydrocarbons.
• Fluorescence Enhancement by Supramolecular Sequestration of a C54-Nanographene Trisimide by Hexabenzocoronene. Pigulski, Bartłomiej; Shoyama, Kazutaka; Sun, Meng-Jia; Würthner, Frank. In J. Am. Chem. Soc., 144(13), pp. 5718–5722. 2022.
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  A supramolecular trilayer nanographene complex consisting of a newly synthesized D3h-symmetric C 54-nanographene trisimide (NTI 1) and two hexabenzocoronenes (HBC) has been obtained by self-assembly. This 1:2 complex is structurally well- defined according to UV/vis and single crystal X-ray studies and exhibits high thermodynamic stability even in polar halogenated solvents. Complexation of NTI 1 by two HBC molecules protects the NTI 1 π-surface efficiently from oxygen quenching, thereby leading to a sequestration-induced fluorescence enhancement under ambient conditions.

  @article{Pigulski_2022, abstract = {A supramolecular trilayer nanographene complex consisting of a newly synthesized D3h-symmetric C 54-nanographene trisimide (NTI 1) and two hexabenzocoronenes (HBC) has been obtained by self-assembly. This 1:2 complex is structurally well- defined according to UV/vis and single crystal X-ray studies and exhibits high thermodynamic stability even in polar halogenated solvents. Complexation of NTI 1 by two HBC molecules protects the NTI 1 π-surface efficiently from oxygen quenching, thereby leading to a sequestration-induced fluorescence enhancement under ambient conditions.}, author = {Pigulski, Bartłomiej and Shoyama, Kazutaka and Sun, Meng-Jia and Würthner, Frank}, journal = {J. Am. Chem. Soc.}, keywords = {myown}, month = {03}, number = 13, pages = {5718–5722}, publisher = {American Chemical Society (ACS)}, title = {Fluorescence Enhancement by Supramolecular Sequestration of a C54-Nanographene Trisimide by Hexabenzocoronene}, volume = 144, year = 2022 }

  %0 Journal Article %1 Pigulski_2022 %A Pigulski, Bartłomiej %A Shoyama, Kazutaka %A Sun, Meng-Jia %A Würthner, Frank %D 2022 %I American Chemical Society (ACS) %J J. Am. Chem. Soc. %N 13 %P 5718--5722 %R 10.1021/jacs.2c00142 %T Fluorescence Enhancement by Supramolecular Sequestration of a C54-Nanographene Trisimide by Hexabenzocoronene %U https://doi.org/10.1021%2Fjacs.2c00142 %V 144 %X A supramolecular trilayer nanographene complex consisting of a newly synthesized D3h-symmetric C 54-nanographene trisimide (NTI 1) and two hexabenzocoronenes (HBC) has been obtained by self-assembly. This 1:2 complex is structurally well- defined according to UV/vis and single crystal X-ray studies and exhibits high thermodynamic stability even in polar halogenated solvents. Complexation of NTI 1 by two HBC molecules protects the NTI 1 π-surface efficiently from oxygen quenching, thereby leading to a sequestration-induced fluorescence enhancement under ambient conditions.
• Supramolecular Substructure of C60-Embedded Schwarzite. Zhu, Chongwei; Shoyama, Kazutaka; Niyas, M. A.; Würthner, Frank. In J. Am. Chem. Soc., 144(36), pp. 16282–16286. 2022.
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  Herein we present a new concept of carbon allotrope, namely, fullerene-embedded schwarzite. We isolated crystals of fullerene embedded in 4 equiv of a negatively curved polycyclic aromatic hydrocarbon (PAH), 1, which could be viewed as a substructure of the hypothetical fullerene–schwarzite complex. On the basis of crystal structure, the stability of the complex (C60⊂(1)4) was studied by theoretical methods (ALMO-EDA), showing that the noncovalent interactions driven by dispersion forces is key for stabilizing the complex, which was further supported by noncovalent interactions (NCI) plots and Hirshfeld-surface analyses. Our findings of C60⊂(1)4 provide a perspective toward the development of novel sp2-carbon allotropes comprising multiple components.

  @article{Zhu_2022, abstract = {Herein we present a new concept of carbon allotrope, namely, fullerene-embedded schwarzite. We isolated crystals of fullerene embedded in 4 equiv of a negatively curved polycyclic aromatic hydrocarbon (PAH), 1, which could be viewed as a substructure of the hypothetical fullerene–schwarzite complex. On the basis of crystal structure, the stability of the complex (C60⊂(1)4) was studied by theoretical methods (ALMO-EDA), showing that the noncovalent interactions driven by dispersion forces is key for stabilizing the complex, which was further supported by noncovalent interactions (NCI) plots and Hirshfeld-surface analyses. Our findings of C60⊂(1)4 provide a perspective toward the development of novel sp2-carbon allotropes comprising multiple components.}, author = {Zhu, Chongwei and Shoyama, Kazutaka and Niyas, M. A. and Würthner, Frank}, journal = {J. Am. Chem. Soc.}, keywords = {myown}, month = {08}, number = 36, pages = {16282–16286}, publisher = {American Chemical Society ({ACS})}, title = {Supramolecular Substructure of C60-Embedded Schwarzite}, volume = 144, year = 2022 }

  %0 Journal Article %1 Zhu_2022 %A Zhu, Chongwei %A Shoyama, Kazutaka %A Niyas, M. A. %A Würthner, Frank %D 2022 %I American Chemical Society (ACS) %J J. Am. Chem. Soc. %N 36 %P 16282--16286 %R 10.1021/jacs.2c06933 %T Supramolecular Substructure of C60-Embedded Schwarzite %U https://doi.org/10.1021%2Fjacs.2c06933 %V 144 %X Herein we present a new concept of carbon allotrope, namely, fullerene-embedded schwarzite. We isolated crystals of fullerene embedded in 4 equiv of a negatively curved polycyclic aromatic hydrocarbon (PAH), 1, which could be viewed as a substructure of the hypothetical fullerene–schwarzite complex. On the basis of crystal structure, the stability of the complex (C60⊂(1)4) was studied by theoretical methods (ALMO-EDA), showing that the noncovalent interactions driven by dispersion forces is key for stabilizing the complex, which was further supported by noncovalent interactions (NCI) plots and Hirshfeld-surface analyses. Our findings of C60⊂(1)4 provide a perspective toward the development of novel sp2-carbon allotropes comprising multiple components.
• Yellow Light-Emitting Highly Soluble Perylene Bisimide Dyes by Acetalization of Bay-Hydroxy Groups. Nagler, Oliver; Krause, Ana-Maria; Shoyama, Kazutaka; Stolte, Matthias; Dubey, Rajeev K.; Liu, Linlin; Xie, Zengqi; Würthner, Frank. In Org. Lett., 24(37), pp. 6839–6844. 2022.
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  A new class of perylene bisimide (PBI) derivatives is introduced by bridging 1,12- and 1,6,7,12-hydroxy functionalized bay positions with oxygen–carbon–oxygen linker(s). This functionalization rigidifies the inherently twisted bay-substituted perylene core to afford dyes of high stability and solubility that are characterized by vibronically well-resolved absorption and fluorescence spectra and intense yellow emission with quantum yields close to 100%.

  @article{Nagler_2022, abstract = {A new class of perylene bisimide (PBI) derivatives is introduced by bridging 1,12- and 1,6,7,12-hydroxy functionalized bay positions with oxygen–carbon–oxygen linker(s). This functionalization rigidifies the inherently twisted bay-substituted perylene core to afford dyes of high stability and solubility that are characterized by vibronically well-resolved absorption and fluorescence spectra and intense yellow emission with quantum yields close to 100%.}, author = {Nagler, Oliver and Krause, Ana-Maria and Shoyama, Kazutaka and Stolte, Matthias and Dubey, Rajeev K. and Liu, Linlin and Xie, Zengqi and Würthner, Frank}, journal = {Org. Lett.}, keywords = {myown}, month = {09}, number = 37, pages = {6839–6844}, publisher = {American Chemical Society ({ACS})}, title = {Yellow Light-Emitting Highly Soluble Perylene Bisimide Dyes by Acetalization of Bay-Hydroxy Groups}, volume = 24, year = 2022 }

  %0 Journal Article %1 Nagler_2022 %A Nagler, Oliver %A Krause, Ana-Maria %A Shoyama, Kazutaka %A Stolte, Matthias %A Dubey, Rajeev K. %A Liu, Linlin %A Xie, Zengqi %A Würthner, Frank %D 2022 %I American Chemical Society (ACS) %J Org. Lett. %N 37 %P 6839--6844 %R 10.1021/acs.orglett.2c02764 %T Yellow Light-Emitting Highly Soluble Perylene Bisimide Dyes by Acetalization of Bay-Hydroxy Groups %U https://doi.org/10.1021%2Facs.orglett.2c02764 %V 24 %X A new class of perylene bisimide (PBI) derivatives is introduced by bridging 1,12- and 1,6,7,12-hydroxy functionalized bay positions with oxygen–carbon–oxygen linker(s). This functionalization rigidifies the inherently twisted bay-substituted perylene core to afford dyes of high stability and solubility that are characterized by vibronically well-resolved absorption and fluorescence spectra and intense yellow emission with quantum yields close to 100%.
• Organic Light-Emitting Diodes Based on Silandiol-Bay-Bridged Perylene Bisimides. Brust, Felix; Nagler, Oliver; Shoyama, Kazutaka; Stolte, Matthias; Würthner, Frank. In Adv. Optical Mater., 11(5). 2022.
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  Perylene bisimides (PBIs) are among the best fluorophores but have to be enwrapped for optoelectronic applications by large and heavy substituents to prevent their ππ-stacking, which is known to accelerate non-radiative decay processes in the solid state. Here, light-weight di-tert-butylsilyl groups are introduced to bridge 1,12-dihydroxy and 1,6,7,12-tetrahydroxy PBIs to afford sublimable dyes for vacuum-processed optoelectronic devices. For both new compounds, this substitution provides a twisted and shielded perylene π-core whose, via OSiObridges, rigid structure affords well-resolved absorption and emission spectra with strong fluorescence in solution, as well as in the solid state. The usefulness of these dyes for vacuum-processed optoelectronic devices is demonstrated in organic light-emitting diodes (OLEDs) that show monomer-like emission spectra and high maximum external quantum efficiency (EQEmax) values of up to 3.1% for the doubly silicon-bridged PBI.

  @article{Brust_2022, abstract = {Perylene bisimides (PBIs) are among the best fluorophores but have to be enwrapped for optoelectronic applications by large and heavy substituents to prevent their ππ-stacking, which is known to accelerate non-radiative decay processes in the solid state. Here, light-weight di-tert-butylsilyl groups are introduced to bridge 1,12-dihydroxy and 1,6,7,12-tetrahydroxy PBIs to afford sublimable dyes for vacuum-processed optoelectronic devices. For both new compounds, this substitution provides a twisted and shielded perylene π-core whose, via OSiObridges, rigid structure affords well-resolved absorption and emission spectra with strong fluorescence in solution, as well as in the solid state. The usefulness of these dyes for vacuum-processed optoelectronic devices is demonstrated in organic light-emitting diodes (OLEDs) that show monomer-like emission spectra and high maximum external quantum efficiency (EQEmax) values of up to 3.1% for the doubly silicon-bridged PBI.}, author = {Brust, Felix and Nagler, Oliver and Shoyama, Kazutaka and Stolte, Matthias and Würthner, Frank}, journal = {Adv. Optical Mater.}, keywords = {myown}, month = 12, number = 5, publisher = {Wiley}, title = {Organic Light-Emitting Diodes Based on Silandiol-Bay-Bridged Perylene Bisimides}, volume = 11, year = 2022 }

  %0 Journal Article %1 Brust_2022 %A Brust, Felix %A Nagler, Oliver %A Shoyama, Kazutaka %A Stolte, Matthias %A Würthner, Frank %D 2022 %I Wiley %J Adv. Optical Mater. %N 5 %R 10.1002/adom.202202676 %T Organic Light-Emitting Diodes Based on Silandiol-Bay-Bridged Perylene Bisimides %U https://doi.org/10.1002%2Fadom.202202676 %V 11 %X Perylene bisimides (PBIs) are among the best fluorophores but have to be enwrapped for optoelectronic applications by large and heavy substituents to prevent their ππ-stacking, which is known to accelerate non-radiative decay processes in the solid state. Here, light-weight di-tert-butylsilyl groups are introduced to bridge 1,12-dihydroxy and 1,6,7,12-tetrahydroxy PBIs to afford sublimable dyes for vacuum-processed optoelectronic devices. For both new compounds, this substitution provides a twisted and shielded perylene π-core whose, via OSiObridges, rigid structure affords well-resolved absorption and emission spectra with strong fluorescence in solution, as well as in the solid state. The usefulness of these dyes for vacuum-processed optoelectronic devices is demonstrated in organic light-emitting diodes (OLEDs) that show monomer-like emission spectra and high maximum external quantum efficiency (EQEmax) values of up to 3.1% for the doubly silicon-bridged PBI.
• Excited states and spin–orbit coupling in chalcogen substituted perylene diimides and their radical anions. Mentzel, Paul; Holzapfel, Marco; Schmiedel, Alexander; Krummenacher, Ivo; Braunschweig, Holger; Wodyński, Artur; Kaupp, Martin; Würthner, Frank; Lambert, Christoph. In Phys. Chem. Chem. Phys., 24(42), pp. 26254–26268. 2022.
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  While spin–orbit coupling does not play a decisive role in the photophysics of unsubstituted perylene diimides (PDI), this changes dramatically when two phenylselenyl or phenyltelluryl substituents were attached to the PDI bay positions. In the series of PhO-, PhS-, PhSe-, and PhTe-substituted PDIs we observed strongly decreasing fluorescence quantum yield as a consequence of strongly increasing intersystem crossing (ISC) rate, measured by transient absorption spectroscopy with fs- and ns-time resolution as well as by broadband fluorescence upconversion. Time-dependent density functional calculations suggest increasing spin–orbit coupling due to the internal heavy-atom effect as the reason for fast ISC. In case of the selenium PDI derivative we found significant singlet oxygen sensitization via the PDI triplet state. The corresponding radical anions of the chalcogen substituted PDIs were also prepared and investigated by optical and EPR spectroscopy. Here, the increasing SOC results in an increase of the g-tensor anisotropy, and of the isotropic g-value in solution, albeit quasirelativistic density functional calculations show only a relatively small fraction of the spin density to be located on the chalcogen atom.

  @article{D2CP02723B, abstract = {While spin–orbit coupling does not play a decisive role in the photophysics of unsubstituted perylene diimides (PDI){,} this changes dramatically when two phenylselenyl or phenyltelluryl substituents were attached to the PDI bay positions. In the series of PhO-{,} PhS-{,} PhSe-{,} and PhTe-substituted PDIs we observed strongly decreasing fluorescence quantum yield as a consequence of strongly increasing intersystem crossing (ISC) rate{,} measured by transient absorption spectroscopy with fs- and ns-time resolution as well as by broadband fluorescence upconversion. Time-dependent density functional calculations suggest increasing spin–orbit coupling due to the internal heavy-atom effect as the reason for fast ISC. In case of the selenium PDI derivative we found significant singlet oxygen sensitization via the PDI triplet state. The corresponding radical anions of the chalcogen substituted PDIs were also prepared and investigated by optical and EPR spectroscopy. Here{,} the increasing SOC results in an increase of the g-tensor anisotropy{,} and of the isotropic g-value in solution{,} albeit quasirelativistic density functional calculations show only a relatively small fraction of the spin density to be located on the chalcogen atom.}, author = {Mentzel, Paul and Holzapfel, Marco and Schmiedel, Alexander and Krummenacher, Ivo and Braunschweig, Holger and Wodyński, Artur and Kaupp, Martin and Würthner, Frank and Lambert, Christoph}, journal = {Phys. Chem. Chem. Phys.}, keywords = {myown}, number = 42, pages = {26254-26268}, publisher = {The Royal Society of Chemistry}, title = {Excited states and spin–orbit coupling in chalcogen substituted perylene diimides and their radical anions}, volume = 24, year = 2022 }

  %0 Journal Article %1 D2CP02723B %A Mentzel, Paul %A Holzapfel, Marco %A Schmiedel, Alexander %A Krummenacher, Ivo %A Braunschweig, Holger %A Wodyński, Artur %A Kaupp, Martin %A Würthner, Frank %A Lambert, Christoph %D 2022 %I The Royal Society of Chemistry %J Phys. Chem. Chem. Phys. %N 42 %P 26254-26268 %R 10.1039/D2CP02723B %T Excited states and spin–orbit coupling in chalcogen substituted perylene diimides and their radical anions %U http://dx.doi.org/10.1039/D2CP02723B %V 24 %X While spin–orbit coupling does not play a decisive role in the photophysics of unsubstituted perylene diimides (PDI), this changes dramatically when two phenylselenyl or phenyltelluryl substituents were attached to the PDI bay positions. In the series of PhO-, PhS-, PhSe-, and PhTe-substituted PDIs we observed strongly decreasing fluorescence quantum yield as a consequence of strongly increasing intersystem crossing (ISC) rate, measured by transient absorption spectroscopy with fs- and ns-time resolution as well as by broadband fluorescence upconversion. Time-dependent density functional calculations suggest increasing spin–orbit coupling due to the internal heavy-atom effect as the reason for fast ISC. In case of the selenium PDI derivative we found significant singlet oxygen sensitization via the PDI triplet state. The corresponding radical anions of the chalcogen substituted PDIs were also prepared and investigated by optical and EPR spectroscopy. Here, the increasing SOC results in an increase of the g-tensor anisotropy, and of the isotropic g-value in solution, albeit quasirelativistic density functional calculations show only a relatively small fraction of the spin density to be located on the chalcogen atom.
• Energy transfer in supramolecular calix[4]arene-Perylene bisimide dye light harvesting building blocks: Resolving loss processes with simultaneous target analysis. van Stokkum, Ivo H.M.; Wohlmuth, Catharina; Würthner, Frank; Williams, René M. In Journal of Photochemistry and Photobiology, 12, p. 100154. 2022.
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  By the application of simultaneous target analysis of multiple femtosecond transient absorption data sets we have identified two loss channels within multi-chromophoric light harvesting arrays. Perylene bisimide-calix[4]arene arrays composed of up to three different types of perylene bisimide (PBI) chromophores, orange (o), red (r), and green (g) PBIs (named after their colors as solids), have previously been studied by transient absorption spectroscopy (Hippius et al., J. Phys. Chem C 112:2476, 2008) and here we present a simultaneous target analysis of those data matrices. A covalent system containing the red chromophore (r) and calix[4]arene (c), the rc system, shows extensive spectral evolution that can be described with four excited states (r1*→r2*→r3*→r4*→ground state). In the Perylene Orange calix[4]arene system (oc), a radical pair (ocRP) can be formed by photoinduced electron transfer (Hippius et al., J. Phys. Chem C 111:13988, 2007). In a simultaneous target analysis of the multichromophoric systems ocr, rcocr and ocrco the properties of rc and oc are integrated, and excitation energy transfer (EET) from o* to r* occurs. In addition, we demonstrate that the final Species Associated Difference Spectrum (SADS) also contains o bleach features that indicate an excitonic interaction, for ocr, rcocr and ocrco. In a simultaneous target analysis of rcg and gcrcg the properties of rc are integrated, and next to EET to g* we can resolve the formation of a new rcgRP that is formed from r1* or r2*, and represents a loss of 7 and 12%, respectively. In a simultaneous target analysis of ocrcg the properties of ocr and rcg are integrated, arriving at a consistent picture with an energy transfer quantum yield of formation of the excited state of the green PBI (g*) of 80%.

  @article{van_Stokkum_2022, abstract = {By the application of simultaneous target analysis of multiple femtosecond transient absorption data sets we have identified two loss channels within multi-chromophoric light harvesting arrays. Perylene bisimide-calix[4]arene arrays composed of up to three different types of perylene bisimide (PBI) chromophores, orange (o), red (r), and green (g) PBIs (named after their colors as solids), have previously been studied by transient absorption spectroscopy (Hippius et al., J. Phys. Chem C 112:2476, 2008) and here we present a simultaneous target analysis of those data matrices. A covalent system containing the red chromophore (r) and calix[4]arene (c), the rc system, shows extensive spectral evolution that can be described with four excited states (r1*→r2*→r3*→r4*→ground state). In the Perylene Orange calix[4]arene system (oc), a radical pair (ocRP) can be formed by photoinduced electron transfer (Hippius et al., J. Phys. Chem C 111:13988, 2007). In a simultaneous target analysis of the multichromophoric systems ocr, rcocr and ocrco the properties of rc and oc are integrated, and excitation energy transfer (EET) from o* to r* occurs. In addition, we demonstrate that the final Species Associated Difference Spectrum (SADS) also contains o bleach features that indicate an excitonic interaction, for ocr, rcocr and ocrco. In a simultaneous target analysis of rcg and gcrcg the properties of rc are integrated, and next to EET to g* we can resolve the formation of a new rcgRP that is formed from r1* or r2*, and represents a loss of 7 and 12%, respectively. In a simultaneous target analysis of ocrcg the properties of ocr and rcg are integrated, arriving at a consistent picture with an energy transfer quantum yield of formation of the excited state of the green PBI (g*) of 80%.}, author = {van Stokkum, Ivo H.M. and Wohlmuth, Catharina and Würthner, Frank and Williams, René M.}, journal = {Journal of Photochemistry and Photobiology}, keywords = {myown}, month = 12, pages = 100154, publisher = {Elsevier}, title = {Energy transfer in supramolecular calix[4]arene-Perylene bisimide dye light harvesting building blocks: Resolving loss processes with simultaneous target analysis}, volume = 12, year = 2022 }

  %0 Journal Article %1 van_Stokkum_2022 %A van Stokkum, Ivo H.M. %A Wohlmuth, Catharina %A Würthner, Frank %A Williams, René M. %D 2022 %I Elsevier %J Journal of Photochemistry and Photobiology %P 100154 %R 10.1016/j.jpap.2022.100154 %T Energy transfer in supramolecular calix[4]arene-Perylene bisimide dye light harvesting building blocks: Resolving loss processes with simultaneous target analysis %U https://doi.org/10.1016%2Fj.jpap.2022.100154 %V 12 %X By the application of simultaneous target analysis of multiple femtosecond transient absorption data sets we have identified two loss channels within multi-chromophoric light harvesting arrays. Perylene bisimide-calix[4]arene arrays composed of up to three different types of perylene bisimide (PBI) chromophores, orange (o), red (r), and green (g) PBIs (named after their colors as solids), have previously been studied by transient absorption spectroscopy (Hippius et al., J. Phys. Chem C 112:2476, 2008) and here we present a simultaneous target analysis of those data matrices. A covalent system containing the red chromophore (r) and calix[4]arene (c), the rc system, shows extensive spectral evolution that can be described with four excited states (r1*→r2*→r3*→r4*→ground state). In the Perylene Orange calix[4]arene system (oc), a radical pair (ocRP) can be formed by photoinduced electron transfer (Hippius et al., J. Phys. Chem C 111:13988, 2007). In a simultaneous target analysis of the multichromophoric systems ocr, rcocr and ocrco the properties of rc and oc are integrated, and excitation energy transfer (EET) from o* to r* occurs. In addition, we demonstrate that the final Species Associated Difference Spectrum (SADS) also contains o bleach features that indicate an excitonic interaction, for ocr, rcocr and ocrco. In a simultaneous target analysis of rcg and gcrcg the properties of rc are integrated, and next to EET to g* we can resolve the formation of a new rcgRP that is formed from r1* or r2*, and represents a loss of 7 and 12%, respectively. In a simultaneous target analysis of ocrcg the properties of ocr and rcg are integrated, arriving at a consistent picture with an energy transfer quantum yield of formation of the excited state of the green PBI (g*) of 80%.
• Supramolecularly Engineered Bulk-Heterojunction Solar Cells with Self-Assembled Non-Fullerene Nanographene Tetraimide Acceptors. Menekse, Kaan; Mahl, Magnus; Albert, Julius; Niyas, M. A.; Shoyama, Kazutaka; Stolte, Matthias; Würthner, Frank. In Solar RRL, 7(2), p. 2200895. 2022.
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  A series of novel imide-functionalized C64 nanographenes is investigated as acceptor components in organic solar cells (OSCs) in combination with donor polymer PM6. These electron-poor molecules either prevail as a monomer or self-assemble into dimers in the OSC active layer depending on the chosen imide substituents. This allows for the controlled stacking of electron-poor and electron-rich π–scaffolds to establish a novel class of non-fullerene acceptor materials to tailor the bulk-heterojunction morphology of the OSCs. The best performance is observed for derivatives that are able to self-assemble into dimers, reaching power conversion efficiencies of up to 7.1%.

  @article{Menekse_2022, abstract = {A series of novel imide-functionalized C64 nanographenes is investigated as acceptor components in organic solar cells (OSCs) in combination with donor polymer PM6. These electron-poor molecules either prevail as a monomer or self-assemble into dimers in the OSC active layer depending on the chosen imide substituents. This allows for the controlled stacking of electron-poor and electron-rich π–scaffolds to establish a novel class of non-fullerene acceptor materials to tailor the bulk-heterojunction morphology of the OSCs. The best performance is observed for derivatives that are able to self-assemble into dimers, reaching power conversion efficiencies of up to 7.1%.}, author = {Menekse, Kaan and Mahl, Magnus and Albert, Julius and Niyas, M. A. and Shoyama, Kazutaka and Stolte, Matthias and Würthner, Frank}, journal = {Solar RRL}, keywords = {myown}, month = 12, number = 2, pages = 2200895, publisher = {Wiley}, title = {Supramolecularly Engineered Bulk-Heterojunction Solar Cells with Self-Assembled Non-Fullerene Nanographene Tetraimide Acceptors}, volume = 7, year = 2022 }

  %0 Journal Article %1 Menekse_2022 %A Menekse, Kaan %A Mahl, Magnus %A Albert, Julius %A Niyas, M. A. %A Shoyama, Kazutaka %A Stolte, Matthias %A Würthner, Frank %D 2022 %I Wiley %J Solar RRL %N 2 %P 2200895 %R 10.1002/solr.202200895 %T Supramolecularly Engineered Bulk-Heterojunction Solar Cells with Self-Assembled Non-Fullerene Nanographene Tetraimide Acceptors %U https://doi.org/10.1002%2Fsolr.202200895 %V 7 %X A series of novel imide-functionalized C64 nanographenes is investigated as acceptor components in organic solar cells (OSCs) in combination with donor polymer PM6. These electron-poor molecules either prevail as a monomer or self-assemble into dimers in the OSC active layer depending on the chosen imide substituents. This allows for the controlled stacking of electron-poor and electron-rich π–scaffolds to establish a novel class of non-fullerene acceptor materials to tailor the bulk-heterojunction morphology of the OSCs. The best performance is observed for derivatives that are able to self-assemble into dimers, reaching power conversion efficiencies of up to 7.1%.
• Activating Organic Phosphorescence via Heavy Metal-π Interaction Induced Intersystem Crossing. Sun, Meng-Jia; Anhalt, Olga; Sárosi, Menyhárt B.; Stolte, Matthias; Würthner, Frank. In Adv. Mater., 34(51), p. 2207331. 2022.
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  Heavy-atom-containing clusters, nanocrystals, and other semiconductors can sensitize the triplet states of their surface-bonded chromophores, but the energy loss, such as nonradiative deactivation, often prevents the synergistic light emission in their solid-state coassemblies. Cocrystallization allows new combinations of molecules with complementary properties for achieving functionalities not available in single components. Here, the cocrystal formation that employs platinum(II) acetylacetonate (Pt(acac)2) as a triplet sensitizer and electron-deficient 1,4,5,8-naphthalene diimides (NDIs) as organic phosphors is reported. The hybrid cocrystals exhibit room-temperature phosphorescence confined in the low-lying, long-lived triplet state of NDIs with photoluminescence (PL) quantum yield (ΦPL) exceeding 25% and a phosphorescence lifetime (τPh) of 156 µs. This remarkable PL property benefits from the noncovalent electronic and spin–orbital coupling between the constituents.

  @article{Sun_2022, abstract = {Heavy-atom-containing clusters, nanocrystals, and other semiconductors can sensitize the triplet states of their surface-bonded chromophores, but the energy loss, such as nonradiative deactivation, often prevents the synergistic light emission in their solid-state coassemblies. Cocrystallization allows new combinations of molecules with complementary properties for achieving functionalities not available in single components. Here, the cocrystal formation that employs platinum(II) acetylacetonate (Pt(acac)2) as a triplet sensitizer and electron-deficient 1,4,5,8-naphthalene diimides (NDIs) as organic phosphors is reported. The hybrid cocrystals exhibit room-temperature phosphorescence confined in the low-lying, long-lived triplet state of NDIs with photoluminescence (PL) quantum yield (ΦPL) exceeding 25% and a phosphorescence lifetime (τPh) of 156 µs. This remarkable PL property benefits from the noncovalent electronic and spin–orbital coupling between the constituents.}, author = {Sun, Meng-Jia and Anhalt, Olga and Sárosi, Menyhárt B. and Stolte, Matthias and Würthner, Frank}, journal = {Adv. Mater.}, keywords = {myown}, month = 11, number = 51, pages = 2207331, publisher = {Wiley}, title = {Activating Organic Phosphorescence via Heavy Metal-π Interaction Induced Intersystem Crossing}, volume = 34, year = 2022 }

  %0 Journal Article %1 Sun_2022 %A Sun, Meng-Jia %A Anhalt, Olga %A Sárosi, Menyhárt B. %A Stolte, Matthias %A Würthner, Frank %D 2022 %I Wiley %J Adv. Mater. %N 51 %P 2207331 %R 10.1002/adma.202207331 %T Activating Organic Phosphorescence via Heavy Metal-π Interaction Induced Intersystem Crossing %U https://doi.org/10.1002%2Fadma.202207331 %V 34 %X Heavy-atom-containing clusters, nanocrystals, and other semiconductors can sensitize the triplet states of their surface-bonded chromophores, but the energy loss, such as nonradiative deactivation, often prevents the synergistic light emission in their solid-state coassemblies. Cocrystallization allows new combinations of molecules with complementary properties for achieving functionalities not available in single components. Here, the cocrystal formation that employs platinum(II) acetylacetonate (Pt(acac)2) as a triplet sensitizer and electron-deficient 1,4,5,8-naphthalene diimides (NDIs) as organic phosphors is reported. The hybrid cocrystals exhibit room-temperature phosphorescence confined in the low-lying, long-lived triplet state of NDIs with photoluminescence (PL) quantum yield (ΦPL) exceeding 25% and a phosphorescence lifetime (τPh) of 156 µs. This remarkable PL property benefits from the noncovalent electronic and spin–orbital coupling between the constituents.
• Axially chiral indolenine derived chromophore dimers and their chiroptical absorption and emission properties. Freytag, Emely; Holzapfel, Marco; Swain, Asim; Bringmann, Gerhard; Stolte, Matthias; Würthner, Frank; Lambert, Christoph. In Chem. Sci., 13(41), pp. 12229–12238. 2022.
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  Yamamoto homocoupling of two chiral oxindoles led to the atropo-diastereoselective formation of an axially chiral oxindole dimer. This building block served as the starting material for the syntheses of axially chiral squaraine and merocyanine chromophore dimers. These dimers show pronounced chiroptical properties, this is, outstandingly high ECD signals (Δε up to ca. 1500 M−1 cm−1) as a couplet with positive Cotton effect for the P-configuration around the biaryl axis and a negative Cotton effect for the M-configuration. All investigated dimers also exhibit pronounced circularly polarised emission with anisotropy values of ca. 10−3 cgs. Time-dependent density functional calculations were used to analyse the three contributions (local one electron, electric–magnetic coupling, and exciton coupling) to the rotational strength applying the Rosenfeld equation to excitonically coupled chromophores. While the exciton coupling term proves to be the dominant one, the electric–magnetic coupling possesses the same sign and adds significantly to the total rotational strength owing to a favourable geometric arrangement of the two chromophores within the dimer.

  @article{D2SC04600H, abstract = {Yamamoto homocoupling of two chiral oxindoles led to the atropo-diastereoselective formation of an axially chiral oxindole dimer. This building block served as the starting material for the syntheses of axially chiral squaraine and merocyanine chromophore dimers. These dimers show pronounced chiroptical properties{,} this is{,} outstandingly high ECD signals (Δε up to ca. 1500 M−1 cm−1) as a couplet with positive Cotton effect for the P-configuration around the biaryl axis and a negative Cotton effect for the M-configuration. All investigated dimers also exhibit pronounced circularly polarised emission with anisotropy values of ca. 10−3 cgs. Time-dependent density functional calculations were used to analyse the three contributions (local one electron{,} electric–magnetic coupling{,} and exciton coupling) to the rotational strength applying the Rosenfeld equation to excitonically coupled chromophores. While the exciton coupling term proves to be the dominant one{,} the electric–magnetic coupling possesses the same sign and adds significantly to the total rotational strength owing to a favourable geometric arrangement of the two chromophores within the dimer.}, author = {Freytag, Emely and Holzapfel, Marco and Swain, Asim and Bringmann, Gerhard and Stolte, Matthias and Würthner, Frank and Lambert, Christoph}, journal = {Chem. Sci.}, keywords = {myown}, number = 41, pages = {12229-12238}, publisher = {The Royal Society of Chemistry}, title = {Axially chiral indolenine derived chromophore dimers and their chiroptical absorption and emission properties}, volume = 13, year = 2022 }

  %0 Journal Article %1 D2SC04600H %A Freytag, Emely %A Holzapfel, Marco %A Swain, Asim %A Bringmann, Gerhard %A Stolte, Matthias %A Würthner, Frank %A Lambert, Christoph %D 2022 %I The Royal Society of Chemistry %J Chem. Sci. %N 41 %P 12229-12238 %R 10.1039/D2SC04600H %T Axially chiral indolenine derived chromophore dimers and their chiroptical absorption and emission properties %U http://dx.doi.org/10.1039/D2SC04600H %V 13 %X Yamamoto homocoupling of two chiral oxindoles led to the atropo-diastereoselective formation of an axially chiral oxindole dimer. This building block served as the starting material for the syntheses of axially chiral squaraine and merocyanine chromophore dimers. These dimers show pronounced chiroptical properties, this is, outstandingly high ECD signals (Δε up to ca. 1500 M−1 cm−1) as a couplet with positive Cotton effect for the P-configuration around the biaryl axis and a negative Cotton effect for the M-configuration. All investigated dimers also exhibit pronounced circularly polarised emission with anisotropy values of ca. 10−3 cgs. Time-dependent density functional calculations were used to analyse the three contributions (local one electron, electric–magnetic coupling, and exciton coupling) to the rotational strength applying the Rosenfeld equation to excitonically coupled chromophores. While the exciton coupling term proves to be the dominant one, the electric–magnetic coupling possesses the same sign and adds significantly to the total rotational strength owing to a favourable geometric arrangement of the two chromophores within the dimer.
• Self-assembled Ru(bda) Coordination Oligomers as Efficient Catalysts for Visible Light-Driven Water Oxidation in Pure Water. Schlossarek, Tim; Stepanenko, Vladimir; Beuerle, Florian; Würthner, Frank. In Angewandte Chemie International Edition, 61(52). 2022.
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  Water-soluble multinuclear complexes based on ruthenium 2,2′-bipyridine-6,6′-dicarboxylate (bda) and ditopic bipyridine linker units are investigated in three-component visible light-driven water oxidation catalysis. Systematic studies revealed a strong enhancement of the catalytic efficiency in the absence of organic co-solvents and with increasing oligomer length. In-depth kinetic and morphological investigations suggest that the enhanced performance is induced by the self-assembly of linear Ru(bda) oligomers into aggregated superstructures. The obtained turnover frequencies (up to 14.9 s−1) and turnover numbers (more than 1000) per ruthenium center are the highest reported so far for Ru(bda)-based photocatalytic water oxidation systems.

  @article{Schlossarek_2022, abstract = {Water-soluble multinuclear complexes based on ruthenium 2,2′-bipyridine-6,6′-dicarboxylate (bda) and ditopic bipyridine linker units are investigated in three-component visible light-driven water oxidation catalysis. Systematic studies revealed a strong enhancement of the catalytic efficiency in the absence of organic co-solvents and with increasing oligomer length. In-depth kinetic and morphological investigations suggest that the enhanced performance is induced by the self-assembly of linear Ru(bda) oligomers into aggregated superstructures. The obtained turnover frequencies (up to 14.9 s−1) and turnover numbers (more than 1000) per ruthenium center are the highest reported so far for Ru(bda)-based photocatalytic water oxidation systems.}, author = {Schlossarek, Tim and Stepanenko, Vladimir and Beuerle, Florian and Würthner, Frank}, journal = {Angewandte Chemie International Edition}, keywords = {myown}, month = 11, number = 52, publisher = {Wiley}, title = {Self-assembled Ru(bda) Coordination Oligomers as Efficient Catalysts for Visible Light-Driven Water Oxidation in Pure Water}, volume = 61, year = 2022 }

  %0 Journal Article %1 Schlossarek_2022 %A Schlossarek, Tim %A Stepanenko, Vladimir %A Beuerle, Florian %A Würthner, Frank %D 2022 %I Wiley %J Angewandte Chemie International Edition %N 52 %R 10.1002/anie.202211445 %T Self-assembled Ru(bda) Coordination Oligomers as Efficient Catalysts for Visible Light-Driven Water Oxidation in Pure Water %U https://doi.org/10.1002%2Fanie.202211445 %V 61 %X Water-soluble multinuclear complexes based on ruthenium 2,2′-bipyridine-6,6′-dicarboxylate (bda) and ditopic bipyridine linker units are investigated in three-component visible light-driven water oxidation catalysis. Systematic studies revealed a strong enhancement of the catalytic efficiency in the absence of organic co-solvents and with increasing oligomer length. In-depth kinetic and morphological investigations suggest that the enhanced performance is induced by the self-assembly of linear Ru(bda) oligomers into aggregated superstructures. The obtained turnover frequencies (up to 14.9 s−1) and turnover numbers (more than 1000) per ruthenium center are the highest reported so far for Ru(bda)-based photocatalytic water oxidation systems.
• Wavelength and Polarization Sensitive Synaptic Phototransistor Based on Organic n-type Semiconductor/Supramolecular J-Aggregate Heterostructure. Kim, Jin Hong; Stolte, Matthias; Würthner, Frank. In ACS Nano, 16(11), pp. 19523–19532. 2022.
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  Human retina- and brain-inspired optoelectronic synapses, which integrate light detection and signal memory functions for data processing, have significant interest because of their potential applications for artificial vision technology. In nature, many animals such as mantis shrimp use polarized light information as well as scalar information including wavelength and intensity; however, a spectropolarimetric organic optoelectronic synapse has been seldom investigated. Herein, we report an organic synaptic phototransistor, consisting of a charge trapping liquid-crystalline perylene bisimide J-aggregate and a charge transporting crystalline dichlorinated naphthalene diimide, that can detect both wavelength and polarization information. The device shows persistent positive and negative photocurrents under low and high voltage conditions, respectively. Furthermore, the aligned organic heterostructure in the thin-film enables linearly polarized light to be absorbed with a dichroic ratio of 1.4 and 3.7 under transverse polarized blue and red light illumination, respectively. These features allow polarized light sensitive postsynaptic functions in the device. Consequently, a simple polarization imaging sensor array is successfully demonstrated using photonic synapses, which suggests that a supramolecular material is an important candidate for the development of spectropolarimetric neuromorphic vision systems.

  @article{Kim_2022, abstract = {Human retina- and brain-inspired optoelectronic synapses, which integrate light detection and signal memory functions for data processing, have significant interest because of their potential applications for artificial vision technology. In nature, many animals such as mantis shrimp use polarized light information as well as scalar information including wavelength and intensity; however, a spectropolarimetric organic optoelectronic synapse has been seldom investigated. Herein, we report an organic synaptic phototransistor, consisting of a charge trapping liquid-crystalline perylene bisimide J-aggregate and a charge transporting crystalline dichlorinated naphthalene diimide, that can detect both wavelength and polarization information. The device shows persistent positive and negative photocurrents under low and high voltage conditions, respectively. Furthermore, the aligned organic heterostructure in the thin-film enables linearly polarized light to be absorbed with a dichroic ratio of 1.4 and 3.7 under transverse polarized blue and red light illumination, respectively. These features allow polarized light sensitive postsynaptic functions in the device. Consequently, a simple polarization imaging sensor array is successfully demonstrated using photonic synapses, which suggests that a supramolecular material is an important candidate for the development of spectropolarimetric neuromorphic vision systems.}, author = {Kim, Jin Hong and Stolte, Matthias and Würthner, Frank}, journal = {ACS Nano}, keywords = {myown}, month = 11, number = 11, pages = {19523–19532}, publisher = {American Chemical Society (ACS)}, title = {Wavelength and Polarization Sensitive Synaptic Phototransistor Based on Organic n-type Semiconductor/Supramolecular J-Aggregate Heterostructure}, volume = 16, year = 2022 }

  %0 Journal Article %1 Kim_2022 %A Kim, Jin Hong %A Stolte, Matthias %A Würthner, Frank %D 2022 %I American Chemical Society (ACS) %J ACS Nano %N 11 %P 19523--19532 %R 10.1021/acsnano.2c09747 %T Wavelength and Polarization Sensitive Synaptic Phototransistor Based on Organic n-type Semiconductor/Supramolecular J-Aggregate Heterostructure %U https://doi.org/10.1021%2Facsnano.2c09747 %V 16 %X Human retina- and brain-inspired optoelectronic synapses, which integrate light detection and signal memory functions for data processing, have significant interest because of their potential applications for artificial vision technology. In nature, many animals such as mantis shrimp use polarized light information as well as scalar information including wavelength and intensity; however, a spectropolarimetric organic optoelectronic synapse has been seldom investigated. Herein, we report an organic synaptic phototransistor, consisting of a charge trapping liquid-crystalline perylene bisimide J-aggregate and a charge transporting crystalline dichlorinated naphthalene diimide, that can detect both wavelength and polarization information. The device shows persistent positive and negative photocurrents under low and high voltage conditions, respectively. Furthermore, the aligned organic heterostructure in the thin-film enables linearly polarized light to be absorbed with a dichroic ratio of 1.4 and 3.7 under transverse polarized blue and red light illumination, respectively. These features allow polarized light sensitive postsynaptic functions in the device. Consequently, a simple polarization imaging sensor array is successfully demonstrated using photonic synapses, which suggests that a supramolecular material is an important candidate for the development of spectropolarimetric neuromorphic vision systems.
• Enzyme-like water preorganization in a synthetic molecular cleft for homogeneous water oxidation catalysis. Noll, Niklas; Krause, Ana-Maria; Beuerle, Florian; Würthner, Frank. In Nature Catalysis, 5(10), pp. 867–877. 2022.
  • [ Abstract ]
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  Inspired by the proficiency of natural enzymes, mimicking of nanoenvironments for precise substrate preorganization is a promising strategy in catalyst design. However, artificial examples of enzyme-like activation of H2O molecules for the challenging oxidative water splitting reaction are hardly explored. Here, we introduce a mononuclear Ru(bda) complex (M1, bda = 2,2′-bipyridine-6,6′-dicarboxylate) equipped with a bipyridine-functionalized ligand to preorganize H2O molecules in front of the metal centre as in enzymatic clefts. The confined pocket of M1 accelerates chemically driven water oxidation at pH 1 by facilitating a water nucleophilic attack pathway with a remarkable turnover frequency of 140 s−1 that is comparable to the oxygen-evolving complex of photosystem II. Single crystal X-ray analysis of M1 under catalytic conditions allowed the observation of a seventh H2O ligand directly coordinated to a RuIII centre. Another H2O substrate is preorganized via a well-defined hydrogen-bonding network for the crucial O–O bond formation by nucleophilic attack.

  @article{Noll_2022, abstract = {Inspired by the proficiency of natural enzymes, mimicking of nanoenvironments for precise substrate preorganization is a promising strategy in catalyst design. However, artificial examples of enzyme-like activation of H2O molecules for the challenging oxidative water splitting reaction are hardly explored. Here, we introduce a mononuclear Ru(bda) complex (M1, bda = 2,2′-bipyridine-6,6′-dicarboxylate) equipped with a bipyridine-functionalized ligand to preorganize H2O molecules in front of the metal centre as in enzymatic clefts. The confined pocket of M1 accelerates chemically driven water oxidation at pH 1 by facilitating a water nucleophilic attack pathway with a remarkable turnover frequency of 140 s−1 that is comparable to the oxygen-evolving complex of photosystem II. Single crystal X-ray analysis of M1 under catalytic conditions allowed the observation of a seventh H2O ligand directly coordinated to a RuIII centre. Another H2O substrate is preorganized via a well-defined hydrogen-bonding network for the crucial O–O bond formation by nucleophilic attack.}, author = {Noll, Niklas and Krause, Ana-Maria and Beuerle, Florian and Würthner, Frank}, journal = {Nature Catalysis}, keywords = {myown}, month = 10, number = 10, pages = {867–877}, publisher = {Springer Science and Business Media {LLC}}, title = {Enzyme-like water preorganization in a synthetic molecular cleft for homogeneous water oxidation catalysis}, volume = 5, year = 2022 }

  %0 Journal Article %1 Noll_2022 %A Noll, Niklas %A Krause, Ana-Maria %A Beuerle, Florian %A Würthner, Frank %D 2022 %I Springer Science and Business Media LLC %J Nature Catalysis %N 10 %P 867--877 %R 10.1038/s41929-022-00843-x %T Enzyme-like water preorganization in a synthetic molecular cleft for homogeneous water oxidation catalysis %U https://doi.org/10.1038%2Fs41929-022-00843-x %V 5 %X Inspired by the proficiency of natural enzymes, mimicking of nanoenvironments for precise substrate preorganization is a promising strategy in catalyst design. However, artificial examples of enzyme-like activation of H2O molecules for the challenging oxidative water splitting reaction are hardly explored. Here, we introduce a mononuclear Ru(bda) complex (M1, bda = 2,2′-bipyridine-6,6′-dicarboxylate) equipped with a bipyridine-functionalized ligand to preorganize H2O molecules in front of the metal centre as in enzymatic clefts. The confined pocket of M1 accelerates chemically driven water oxidation at pH 1 by facilitating a water nucleophilic attack pathway with a remarkable turnover frequency of 140 s−1 that is comparable to the oxygen-evolving complex of photosystem II. Single crystal X-ray analysis of M1 under catalytic conditions allowed the observation of a seventh H2O ligand directly coordinated to a RuIII centre. Another H2O substrate is preorganized via a well-defined hydrogen-bonding network for the crucial O–O bond formation by nucleophilic attack.
• Axially chiral bay-tetraarylated perylene bisimide dyes as non-fullerene acceptors in organic solar cells. Mahlmeister, Bernhard; Renner, Rebecca; Anhalt, Olga; Stolte, Matthias; Würthner, Frank. In J. Mater. Chem. C, 10(7), pp. 2581–2591. 2022.
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  A series of twisted perylene bisimide (PBI) dyes bearing different imide substituents as well as various aryl substituents in 1,6,7,12 bay positions inducing conformationally stable axial chirality are investigated as non-fullerene acceptors (NFAs) in organic solar cells (OSCs). In a comprehensive study, both imide and aryl substituent variations are tested within a simple inverted bulk heterojunction (BHJ) architecture with donor polymer PCE-10. The results are rationalized by single crystal structure analyses revealing the importance of the sterical demand imparted by the substituents in both positions on the packing arrangements. Comparative studies of racemic and enantiopure samples of these axially chiral dyes showed that the OSC performance is only affected by the enantiopurity if the chromophore is not well shielded. In that case, intimate π–π-stacking is disfavored for enantiopure compounds, thereby improving the OSC efficiency significantly by up to 24%. For a more shielded PBI bearing bulky 2,6-diisopropylphenyl (Dipp) substituents at imide and 2-naphthyl at bay positions, a maximum power conversion efficiency (PCEmax) of 4.3% is achieved even for the racemate.

  @article{D1TC04116A, abstract = {A series of twisted perylene bisimide (PBI) dyes bearing different imide substituents as well as various aryl substituents in 1{,}6{,}7{,}12 bay positions inducing conformationally stable axial chirality are investigated as non-fullerene acceptors (NFAs) in organic solar cells (OSCs). In a comprehensive study{,} both imide and aryl substituent variations are tested within a simple inverted bulk heterojunction (BHJ) architecture with donor polymer PCE-10. The results are rationalized by single crystal structure analyses revealing the importance of the sterical demand imparted by the substituents in both positions on the packing arrangements. Comparative studies of racemic and enantiopure samples of these axially chiral dyes showed that the OSC performance is only affected by the enantiopurity if the chromophore is not well shielded. In that case{,} intimate π–π-stacking is disfavored for enantiopure compounds{,} thereby improving the OSC efficiency significantly by up to 24%. For a more shielded PBI bearing bulky 2{,}6-diisopropylphenyl (Dipp) substituents at imide and 2-naphthyl at bay positions{,} a maximum power conversion efficiency (PCEmax) of 4.3% is achieved even for the racemate.}, author = {Mahlmeister, Bernhard and Renner, Rebecca and Anhalt, Olga and Stolte, Matthias and Würthner, Frank}, journal = {J. Mater. Chem. C}, keywords = {myown}, number = 7, pages = {2581-2591}, publisher = {The Royal Society of Chemistry}, title = {Axially chiral bay-tetraarylated perylene bisimide dyes as non-fullerene acceptors in organic solar cells}, volume = 10, year = 2022 }

  %0 Journal Article %1 D1TC04116A %A Mahlmeister, Bernhard %A Renner, Rebecca %A Anhalt, Olga %A Stolte, Matthias %A Würthner, Frank %D 2022 %I The Royal Society of Chemistry %J J. Mater. Chem. C %N 7 %P 2581-2591 %R 10.1039/D1TC04116A %T Axially chiral bay-tetraarylated perylene bisimide dyes as non-fullerene acceptors in organic solar cells %U http://dx.doi.org/10.1039/D1TC04116A %V 10 %X A series of twisted perylene bisimide (PBI) dyes bearing different imide substituents as well as various aryl substituents in 1,6,7,12 bay positions inducing conformationally stable axial chirality are investigated as non-fullerene acceptors (NFAs) in organic solar cells (OSCs). In a comprehensive study, both imide and aryl substituent variations are tested within a simple inverted bulk heterojunction (BHJ) architecture with donor polymer PCE-10. The results are rationalized by single crystal structure analyses revealing the importance of the sterical demand imparted by the substituents in both positions on the packing arrangements. Comparative studies of racemic and enantiopure samples of these axially chiral dyes showed that the OSC performance is only affected by the enantiopurity if the chromophore is not well shielded. In that case, intimate π–π-stacking is disfavored for enantiopure compounds, thereby improving the OSC efficiency significantly by up to 24%. For a more shielded PBI bearing bulky 2,6-diisopropylphenyl (Dipp) substituents at imide and 2-naphthyl at bay positions, a maximum power conversion efficiency (PCEmax) of 4.3% is achieved even for the racemate.
• A Covalent Organic Framework for Cooperative Water Oxidation. Karak, Suvendu; Stepanenko, Vladimir; Addicoat, Matthew A.; Kessler, Philipp; Moser, Simon; Beuerle, Florian; Würthner, Frank. In J. Am. Chem. Soc., 144(38), pp. 17661–17670. 2022.
  • [ Abstract ]
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  The future of water-derived hydrogen as the “sustainable energy source” straightaway bets on the success of the sluggish oxygen-generating half-reaction. The endeavor to emulate the natural photosystem II for efficient water oxidation has been extended across the spectrum of organic and inorganic combinations. However, the achievement has so far been restricted to homogeneous catalysts rather than their pristine heterogeneous forms. The poor structural understanding and control over the mechanistic pathway often impede the overall development. Herein, we have synthesized a highly crystalline covalent organic framework (COF) for chemical and photochemical water oxidation. The interpenetrated structure assures the catalyst stability, as the catalyst’s performance remains unaltered after several cycles. This COF exhibits the highest ever accomplished catalytic activity for such an organometallic crystalline solid-state material where the rate of oxygen evolution is as high as ∼26,000 μmol L–1 s–1 (second-order rate constant k ≈ 1650 μmol L s–1 g–2). The catalyst also proves its exceptional activity (k ≈ 1600 μmol L s–1 g–2) during light-driven water oxidation under very dilute conditions. The cooperative interaction between metal centers in the crystalline network offers 20–30-fold superior activity during chemical as well as photocatalytic water oxidation as compared to its amorphous polymeric counterpart.

  @article{Karak_2022, abstract = {The future of water-derived hydrogen as the “sustainable energy source” straightaway bets on the success of the sluggish oxygen-generating half-reaction. The endeavor to emulate the natural photosystem II for efficient water oxidation has been extended across the spectrum of organic and inorganic combinations. However, the achievement has so far been restricted to homogeneous catalysts rather than their pristine heterogeneous forms. The poor structural understanding and control over the mechanistic pathway often impede the overall development. Herein, we have synthesized a highly crystalline covalent organic framework (COF) for chemical and photochemical water oxidation. The interpenetrated structure assures the catalyst stability, as the catalyst’s performance remains unaltered after several cycles. This COF exhibits the highest ever accomplished catalytic activity for such an organometallic crystalline solid-state material where the rate of oxygen evolution is as high as ∼26,000 μmol L–1 s–1 (second-order rate constant k ≈ 1650 μmol L s–1 g–2). The catalyst also proves its exceptional activity (k ≈ 1600 μmol L s–1 g–2) during light-driven water oxidation under very dilute conditions. The cooperative interaction between metal centers in the crystalline network offers 20–30-fold superior activity during chemical as well as photocatalytic water oxidation as compared to its amorphous polymeric counterpart.}, author = {Karak, Suvendu and Stepanenko, Vladimir and Addicoat, Matthew A. and Kessler, Philipp and Moser, Simon and Beuerle, Florian and Würthner, Frank}, journal = {J. Am. Chem. Soc.}, keywords = {myown}, month = {09}, number = 38, pages = {17661–17670}, publisher = {American Chemical Society ({ACS})}, title = {A Covalent Organic Framework for Cooperative Water Oxidation}, volume = 144, year = 2022 }

  %0 Journal Article %1 Karak_2022 %A Karak, Suvendu %A Stepanenko, Vladimir %A Addicoat, Matthew A. %A Kessler, Philipp %A Moser, Simon %A Beuerle, Florian %A Würthner, Frank %D 2022 %I American Chemical Society (ACS) %J J. Am. Chem. Soc. %N 38 %P 17661--17670 %R 10.1021/jacs.2c07282 %T A Covalent Organic Framework for Cooperative Water Oxidation %U https://doi.org/10.1021%2Fjacs.2c07282 %V 144 %X The future of water-derived hydrogen as the “sustainable energy source” straightaway bets on the success of the sluggish oxygen-generating half-reaction. The endeavor to emulate the natural photosystem II for efficient water oxidation has been extended across the spectrum of organic and inorganic combinations. However, the achievement has so far been restricted to homogeneous catalysts rather than their pristine heterogeneous forms. The poor structural understanding and control over the mechanistic pathway often impede the overall development. Herein, we have synthesized a highly crystalline covalent organic framework (COF) for chemical and photochemical water oxidation. The interpenetrated structure assures the catalyst stability, as the catalyst’s performance remains unaltered after several cycles. This COF exhibits the highest ever accomplished catalytic activity for such an organometallic crystalline solid-state material where the rate of oxygen evolution is as high as ∼26,000 μmol L–1 s–1 (second-order rate constant k ≈ 1650 μmol L s–1 g–2). The catalyst also proves its exceptional activity (k ≈ 1600 μmol L s–1 g–2) during light-driven water oxidation under very dilute conditions. The cooperative interaction between metal centers in the crystalline network offers 20–30-fold superior activity during chemical as well as photocatalytic water oxidation as compared to its amorphous polymeric counterpart.
• Substituent-dependent absorption and fluorescence properties of perylene bisimide radical anions and dianions. Renner, Rebecca; Stolte, Matthias; Heitmüller, Julia; Brixner, Tobias; Lambert, Christoph; Würthner, Frank. In Mater. Horiz., 9(1), pp. 350–359. 2022.

  Original data of the UV-Vis-NIR and fluorescence spectra: DOI 10.5281/zenodo.5849111
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  Perylene-3,4:9,10-bis(dicarboximides) (PBIs) rank among the most important functional dyes and organic semiconductors, but only recently have their radical anions and dianions attracted interest for a variety of applications. Here, we systematically elucidate the functional properties (redox, absorption, and emission) of five PBI anions and dianions bearing different bay-substituents attached to the chromophore core. Cyclic voltammetry measurements reveal the influence of the substituents ranging from electron-withdrawing cyano to electron-donating phenoxy groups on the oxidation and reduction potentials that relate to the HOMO and LUMO levels ranging from −7.07 eV to −6.05 eV and −5.01 eV to −4.05 eV, respectively. Spectroelectrochemical studies reveal a significant number of intense absorption bands in the NIR-spectral range (750–1400 nm) for the radical anions, whereas the dianionic species are characterized by similar spectra to those for the neutral dyes, however being bathochromically shifted and with increased molar extinction coefficients of approximately 100 000 M−1 cm−1. The increase of the transition dipole moment is up to 56% and accompanied by an almost cyanine-like red-shifted (by 300 nm) absorption spectrum for the most electron-poor tetracyanotetrachloro PBI. Whilst the outstanding fluorescence properties of the neutral PBIs are lost for the radical anions, an appreciable near-infrared (NIR) fluorescence with a quantum yield of up to 18% is revealed for the dianions by utilizing a custom-built flow-cell spectroelectrochemistry setup. Time-dependent density functional theory calculations help to assign the absorption bands to the respective electronic transitions.

  @article{D1MH01019K, abstract = {Perylene-3,4:9,10-bis(dicarboximides) (PBIs) rank among the most important functional dyes and organic semiconductors, but only recently have their radical anions and dianions attracted interest for a variety of applications. Here, we systematically elucidate the functional properties (redox, absorption, and emission) of five PBI anions and dianions bearing different bay-substituents attached to the chromophore core. Cyclic voltammetry measurements reveal the influence of the substituents ranging from electron-withdrawing cyano to electron-donating phenoxy groups on the oxidation and reduction potentials that relate to the HOMO and LUMO levels ranging from −7.07 eV to −6.05 eV and −5.01 eV to −4.05 eV, respectively. Spectroelectrochemical studies reveal a significant number of intense absorption bands in the NIR-spectral range (750–1400 nm) for the radical anions, whereas the dianionic species are characterized by similar spectra to those for the neutral dyes, however being bathochromically shifted and with increased molar extinction coefficients of approximately 100 000 M−1 cm−1. The increase of the transition dipole moment is up to 56% and accompanied by an almost cyanine-like red-shifted (by 300 nm) absorption spectrum for the most electron-poor tetracyanotetrachloro PBI. Whilst the outstanding fluorescence properties of the neutral PBIs are lost for the radical anions, an appreciable near-infrared (NIR) fluorescence with a quantum yield of up to 18% is revealed for the dianions by utilizing a custom-built flow-cell spectroelectrochemistry setup. Time-dependent density functional theory calculations help to assign the absorption bands to the respective electronic transitions.}, author = {Renner, Rebecca and Stolte, Matthias and Heitmüller, Julia and Brixner, Tobias and Lambert, Christoph and Würthner, Frank}, journal = {Mater. Horiz.}, keywords = {myown}, note = {Original data of the UV-Vis-NIR and fluorescence spectra: DOI 10.5281/zenodo.5849111}, number = 1, pages = {350-359}, publisher = {The Royal Society of Chemistry}, title = {Substituent-dependent absorption and fluorescence properties of perylene bisimide radical anions and dianions}, volume = 9, year = 2022 }

  %0 Journal Article %1 D1MH01019K %A Renner, Rebecca %A Stolte, Matthias %A Heitmüller, Julia %A Brixner, Tobias %A Lambert, Christoph %A Würthner, Frank %D 2022 %I The Royal Society of Chemistry %J Mater. Horiz. %N 1 %P 350-359 %R 10.1039/D1MH01019K %T Substituent-dependent absorption and fluorescence properties of perylene bisimide radical anions and dianions %U http://dx.doi.org/10.1039/D1MH01019K %V 9 %X Perylene-3,4:9,10-bis(dicarboximides) (PBIs) rank among the most important functional dyes and organic semiconductors, but only recently have their radical anions and dianions attracted interest for a variety of applications. Here, we systematically elucidate the functional properties (redox, absorption, and emission) of five PBI anions and dianions bearing different bay-substituents attached to the chromophore core. Cyclic voltammetry measurements reveal the influence of the substituents ranging from electron-withdrawing cyano to electron-donating phenoxy groups on the oxidation and reduction potentials that relate to the HOMO and LUMO levels ranging from −7.07 eV to −6.05 eV and −5.01 eV to −4.05 eV, respectively. Spectroelectrochemical studies reveal a significant number of intense absorption bands in the NIR-spectral range (750–1400 nm) for the radical anions, whereas the dianionic species are characterized by similar spectra to those for the neutral dyes, however being bathochromically shifted and with increased molar extinction coefficients of approximately 100 000 M−1 cm−1. The increase of the transition dipole moment is up to 56% and accompanied by an almost cyanine-like red-shifted (by 300 nm) absorption spectrum for the most electron-poor tetracyanotetrachloro PBI. Whilst the outstanding fluorescence properties of the neutral PBIs are lost for the radical anions, an appreciable near-infrared (NIR) fluorescence with a quantum yield of up to 18% is revealed for the dianions by utilizing a custom-built flow-cell spectroelectrochemistry setup. Time-dependent density functional theory calculations help to assign the absorption bands to the respective electronic transitions.
• Excited states and spin–orbit coupling in chalcogen substituted perylene diimides and their radical anions. Mentzel, Paul; Holzapfel, Marco; Schmiedel, Alexander; Krummenacher, Ivo; Braunschweig, Holger; Wodyński, Artur; Kaupp, Martin; Würthner, Frank; Lambert, Christoph. In Phys. Chem. Chem. Phys., 24(42), pp. 26254–26268. 2022.
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  While spin–orbit coupling does not play a decisive role in the photophysics of unsubstituted perylene diimides (PDI), this changes dramatically when two phenylselenyl or phenyltelluryl substituents were attached to the PDI bay positions. In the series of PhO-, PhS-, PhSe-, and PhTe-substituted PDIs we observed strongly decreasing fluorescence quantum yield as a consequence of strongly increasing intersystem crossing (ISC) rate, measured by transient absorption spectroscopy with fs- and ns-time resolution as well as by broadband fluorescence upconversion. Time-dependent density functional calculations suggest increasing spin–orbit coupling due to the internal heavy-atom effect as the reason for fast ISC. In case of the selenium PDI derivative we found significant singlet oxygen sensitization via the PDI triplet state. The corresponding radical anions of the chalcogen substituted PDIs were also prepared and investigated by optical and EPR spectroscopy. Here, the increasing SOC results in an increase of the g-tensor anisotropy, and of the isotropic g-value in solution, albeit quasirelativistic density functional calculations show only a relatively small fraction of the spin density to be located on the chalcogen atom.

  @article{D2CP02723B, abstract = {While spin–orbit coupling does not play a decisive role in the photophysics of unsubstituted perylene diimides (PDI){,} this changes dramatically when two phenylselenyl or phenyltelluryl substituents were attached to the PDI bay positions. In the series of PhO-{,} PhS-{,} PhSe-{,} and PhTe-substituted PDIs we observed strongly decreasing fluorescence quantum yield as a consequence of strongly increasing intersystem crossing (ISC) rate{,} measured by transient absorption spectroscopy with fs- and ns-time resolution as well as by broadband fluorescence upconversion. Time-dependent density functional calculations suggest increasing spin–orbit coupling due to the internal heavy-atom effect as the reason for fast ISC. In case of the selenium PDI derivative we found significant singlet oxygen sensitization via the PDI triplet state. The corresponding radical anions of the chalcogen substituted PDIs were also prepared and investigated by optical and EPR spectroscopy. Here{,} the increasing SOC results in an increase of the g-tensor anisotropy{,} and of the isotropic g-value in solution{,} albeit quasirelativistic density functional calculations show only a relatively small fraction of the spin density to be located on the chalcogen atom.}, author = {Mentzel, Paul and Holzapfel, Marco and Schmiedel, Alexander and Krummenacher, Ivo and Braunschweig, Holger and Wodyński, Artur and Kaupp, Martin and Würthner, Frank and Lambert, Christoph}, journal = {Phys. Chem. Chem. Phys.}, keywords = {myown}, number = 42, pages = {26254-26268}, publisher = {The Royal Society of Chemistry}, title = {Excited states and spin–orbit coupling in chalcogen substituted perylene diimides and their radical anions}, volume = 24, year = 2022 }

  %0 Journal Article %1 D2CP02723B %A Mentzel, Paul %A Holzapfel, Marco %A Schmiedel, Alexander %A Krummenacher, Ivo %A Braunschweig, Holger %A Wodyński, Artur %A Kaupp, Martin %A Würthner, Frank %A Lambert, Christoph %D 2022 %I The Royal Society of Chemistry %J Phys. Chem. Chem. Phys. %N 42 %P 26254-26268 %R 10.1039/D2CP02723B %T Excited states and spin–orbit coupling in chalcogen substituted perylene diimides and their radical anions %U http://dx.doi.org/10.1039/D2CP02723B %V 24 %X While spin–orbit coupling does not play a decisive role in the photophysics of unsubstituted perylene diimides (PDI), this changes dramatically when two phenylselenyl or phenyltelluryl substituents were attached to the PDI bay positions. In the series of PhO-, PhS-, PhSe-, and PhTe-substituted PDIs we observed strongly decreasing fluorescence quantum yield as a consequence of strongly increasing intersystem crossing (ISC) rate, measured by transient absorption spectroscopy with fs- and ns-time resolution as well as by broadband fluorescence upconversion. Time-dependent density functional calculations suggest increasing spin–orbit coupling due to the internal heavy-atom effect as the reason for fast ISC. In case of the selenium PDI derivative we found significant singlet oxygen sensitization via the PDI triplet state. The corresponding radical anions of the chalcogen substituted PDIs were also prepared and investigated by optical and EPR spectroscopy. Here, the increasing SOC results in an increase of the g-tensor anisotropy, and of the isotropic g-value in solution, albeit quasirelativistic density functional calculations show only a relatively small fraction of the spin density to be located on the chalcogen atom.
• Peptide Backbone Directed Self-Assembly of Merocyanine Oligomers into Duplex Structures. Liu, Bin; Vonhausen, Yvonne; Schulz, Alexander; Höbartner, Claudia; Würthner, Frank. In Angew. Chem. Int. Ed., 61(21). 2022.
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  The pseudopeptide backbone provided by N-(2-aminoethyl)-glycine oligomers with attached nucleobases has been widely utilized in peptide nucleic acids (PNAs) as DNA mimics. Here we demonstrate the suitability of this backbone for the formation of structurally defined dye stacks. Toward this goal a series of peptide merocyanine (PMC) dye oligomers connected to a N-(2-aminoethyl)-glycine backbone were prepared through peptide synthesis. Our concentration-, temperature- and solvent-dependent UV/Vis absorption studies show that under the control of dipole–dipole interactions, smaller-sized oligomers consisting of one, two or three dyes self-assemble into defined duplex structures containing two up to six chromophores. In contrast, upon further extension of the oligomer, the chosen peptide backbone cannot direct the formation of a defined duplex architecture anymore due to intramolecular aggregation between the dyes. For all aggregate species a moderate aggregation-induced emission enhancement is observed.

  @article{Liu_2022, abstract = {The pseudopeptide backbone provided by N-(2-aminoethyl)-glycine oligomers with attached nucleobases has been widely utilized in peptide nucleic acids (PNAs) as DNA mimics. Here we demonstrate the suitability of this backbone for the formation of structurally defined dye stacks. Toward this goal a series of peptide merocyanine (PMC) dye oligomers connected to a N-(2-aminoethyl)-glycine backbone were prepared through peptide synthesis. Our concentration-, temperature- and solvent-dependent UV/Vis absorption studies show that under the control of dipole–dipole interactions, smaller-sized oligomers consisting of one, two or three dyes self-assemble into defined duplex structures containing two up to six chromophores. In contrast, upon further extension of the oligomer, the chosen peptide backbone cannot direct the formation of a defined duplex architecture anymore due to intramolecular aggregation between the dyes. For all aggregate species a moderate aggregation-induced emission enhancement is observed.}, author = {Liu, Bin and Vonhausen, Yvonne and Schulz, Alexander and Höbartner, Claudia and Würthner, Frank}, journal = {Angew. Chem. Int. Ed.}, keywords = {myown}, month = {03}, number = 21, publisher = {Wiley}, title = {Peptide Backbone Directed Self-Assembly of Merocyanine Oligomers into Duplex Structures}, volume = 61, year = 2022 }

  %0 Journal Article %1 Liu_2022 %A Liu, Bin %A Vonhausen, Yvonne %A Schulz, Alexander %A Höbartner, Claudia %A Würthner, Frank %D 2022 %I Wiley %J Angew. Chem. Int. Ed. %N 21 %R 10.1002/anie.202200120 %T Peptide Backbone Directed Self-Assembly of Merocyanine Oligomers into Duplex Structures %U https://doi.org/10.1002%2Fanie.202200120 %V 61 %X The pseudopeptide backbone provided by N-(2-aminoethyl)-glycine oligomers with attached nucleobases has been widely utilized in peptide nucleic acids (PNAs) as DNA mimics. Here we demonstrate the suitability of this backbone for the formation of structurally defined dye stacks. Toward this goal a series of peptide merocyanine (PMC) dye oligomers connected to a N-(2-aminoethyl)-glycine backbone were prepared through peptide synthesis. Our concentration-, temperature- and solvent-dependent UV/Vis absorption studies show that under the control of dipole–dipole interactions, smaller-sized oligomers consisting of one, two or three dyes self-assemble into defined duplex structures containing two up to six chromophores. In contrast, upon further extension of the oligomer, the chosen peptide backbone cannot direct the formation of a defined duplex architecture anymore due to intramolecular aggregation between the dyes. For all aggregate species a moderate aggregation-induced emission enhancement is observed.
• pi-Extended Pleiadienes by [5+2] Annulation of 1-Boraphenalenes and ortho-Dihaloarenes. Schnitzlein, Matthias; Zhu, Chongwei; Shoyama, Kazutaka; Würthner, Frank. In Chemistry - A European Journal, 28(61). 2022.
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  Palladium-catalyzed [5+2] annulation of 1-boraphenalenes with ortho-dihaloarenes afforded negatively curved π-extended pleiadienes. Two benzo[1,2-i:4,5-i’]dipleiadienes (BDPs) featuring a seven-six-seven-membered ring arrangement were synthesized and investigated. Their crystal structure revealed a unique packing arrangement and theoretical calculations were employed to shed light onto the dynamic behavior of the BDP moiety and its aromaticity. Further, a naphthalene-fused pleiadiene was stitched together by oxidative cyclodehydrogenation to yield an additional five-membered ring. This formal azulene moiety led to distinct changes in optical and redox properties and increased perturbation of the aromatic system.

  @article{Schnitzlein_2022, abstract = {Palladium-catalyzed [5+2] annulation of 1-boraphenalenes with ortho-dihaloarenes afforded negatively curved π-extended pleiadienes. Two benzo[1,2-i:4,5-i’]dipleiadienes (BDPs) featuring a seven-six-seven-membered ring arrangement were synthesized and investigated. Their crystal structure revealed a unique packing arrangement and theoretical calculations were employed to shed light onto the dynamic behavior of the BDP moiety and its aromaticity. Further, a naphthalene-fused pleiadiene was stitched together by oxidative cyclodehydrogenation to yield an additional five-membered ring. This formal azulene moiety led to distinct changes in optical and redox properties and increased perturbation of the aromatic system.}, author = {Schnitzlein, Matthias and Zhu, Chongwei and Shoyama, Kazutaka and Würthner, Frank}, journal = {Chemistry - A European Journal}, keywords = {myown}, month = {08}, number = 61, publisher = {Wiley}, title = {pi-Extended Pleiadienes by [5+2] Annulation of 1-Boraphenalenes and ortho-Dihaloarenes}, volume = 28, year = 2022 }

  %0 Journal Article %1 Schnitzlein_2022 %A Schnitzlein, Matthias %A Zhu, Chongwei %A Shoyama, Kazutaka %A Würthner, Frank %D 2022 %I Wiley %J Chemistry - A European Journal %N 61 %R 10.1002/chem.202202053 %T pi-Extended Pleiadienes by [5+2] Annulation of 1-Boraphenalenes and ortho-Dihaloarenes %U https://doi.org/10.1002%2Fchem.202202053 %V 28 %X Palladium-catalyzed [5+2] annulation of 1-boraphenalenes with ortho-dihaloarenes afforded negatively curved π-extended pleiadienes. Two benzo[1,2-i:4,5-i’]dipleiadienes (BDPs) featuring a seven-six-seven-membered ring arrangement were synthesized and investigated. Their crystal structure revealed a unique packing arrangement and theoretical calculations were employed to shed light onto the dynamic behavior of the BDP moiety and its aromaticity. Further, a naphthalene-fused pleiadiene was stitched together by oxidative cyclodehydrogenation to yield an additional five-membered ring. This formal azulene moiety led to distinct changes in optical and redox properties and increased perturbation of the aromatic system.
• Steering the multiexciton generation in slip-stacked perylene dye array via exciton coupling. Hong, Yongseok; Rudolf, Maximilian; Kim, Munnyon; Kim, Juno; Schembri, Tim; Krause, Ana-Maria; Shoyama, Kazutaka; Bialas, David; Röhr, Merle I. S.; Joo, Taiha; Kim, Hyungjun; Kim, Dongho; Würthner, Frank. In Nat. Commun., 13. 2022.
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  Dye arrays from dimers up to larger oligomers constitute the functional units of natural light harvesting systems as well as organic photonic and photovoltaic materials. Whilst in the past decades many photophysical studies were devoted to molecular dimers for deriving structure-property relationship to unravel the design principles for ideal optoelectronic materials, they fail to accomplish the subsequent processes of charge carrier generation or the detachment of two triplet species in singlet fission (SF). Here, we present a slip-stacked perylene bisimide trimer, which constitutes a bridge between hitherto studied dimer and solid-state materials, to investigate SF mechanisms. This work showcases multiple pathways towards the multiexciton state through direct or excimer-mediated mechanisms by depending upon interchromophoric interaction. These results suggest the comprehensive role of the exciton coupling, exciton delocalization, and excimer state to facilitate the SF process. In this regard, our observations expand the fundamental understanding the structure-property relationship in dye arrays.

  @article{hong2022steering, abstract = {Dye arrays from dimers up to larger oligomers constitute the functional units of natural light harvesting systems as well as organic photonic and photovoltaic materials. Whilst in the past decades many photophysical studies were devoted to molecular dimers for deriving structure-property relationship to unravel the design principles for ideal optoelectronic materials, they fail to accomplish the subsequent processes of charge carrier generation or the detachment of two triplet species in singlet fission (SF). Here, we present a slip-stacked perylene bisimide trimer, which constitutes a bridge between hitherto studied dimer and solid-state materials, to investigate SF mechanisms. This work showcases multiple pathways towards the multiexciton state through direct or excimer-mediated mechanisms by depending upon interchromophoric interaction. These results suggest the comprehensive role of the exciton coupling, exciton delocalization, and excimer state to facilitate the SF process. In this regard, our observations expand the fundamental understanding the structure-property relationship in dye arrays.}, author = {Hong, Yongseok and Rudolf, Maximilian and Kim, Munnyon and Kim, Juno and Schembri, Tim and Krause, Ana-Maria and Shoyama, Kazutaka and Bialas, David and Röhr, Merle I. S. and Joo, Taiha and Kim, Hyungjun and Kim, Dongho and Würthner, Frank}, journal = {Nat. Commun.}, keywords = {myown}, month = {08}, title = {Steering the multiexciton generation in slip-stacked perylene dye array via exciton coupling}, volume = 13, year = 2022 }

  %0 Journal Article %1 hong2022steering %A Hong, Yongseok %A Rudolf, Maximilian %A Kim, Munnyon %A Kim, Juno %A Schembri, Tim %A Krause, Ana-Maria %A Shoyama, Kazutaka %A Bialas, David %A Röhr, Merle I. S. %A Joo, Taiha %A Kim, Hyungjun %A Kim, Dongho %A Würthner, Frank %D 2022 %J Nat. Commun. %R 10.1038/s41467-022-31958-1 %T Steering the multiexciton generation in slip-stacked perylene dye array via exciton coupling %U https://www.nature.com/articles/s41467-022-31958-1 %V 13 %X Dye arrays from dimers up to larger oligomers constitute the functional units of natural light harvesting systems as well as organic photonic and photovoltaic materials. Whilst in the past decades many photophysical studies were devoted to molecular dimers for deriving structure-property relationship to unravel the design principles for ideal optoelectronic materials, they fail to accomplish the subsequent processes of charge carrier generation or the detachment of two triplet species in singlet fission (SF). Here, we present a slip-stacked perylene bisimide trimer, which constitutes a bridge between hitherto studied dimer and solid-state materials, to investigate SF mechanisms. This work showcases multiple pathways towards the multiexciton state through direct or excimer-mediated mechanisms by depending upon interchromophoric interaction. These results suggest the comprehensive role of the exciton coupling, exciton delocalization, and excimer state to facilitate the SF process. In this regard, our observations expand the fundamental understanding the structure-property relationship in dye arrays.

• Nitronyl Nitroxide Bifunctionalized Electron-Poor Chromophores: Synthesis of Stable Dye Biradicals by Lewis Acid Promoted Desilylation. Rausch, Rodger; Krause, Ana-Maria; Krummenacher, Ivo; Braunschweig, Holger; Würthner, Frank. In J. Org. Chem., 86(3), pp. 2447–2457. 2021.
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  Open shell organic molecules bearing π-cores are of great interest for optical, electronic, and magnetic applications but frequently suffer fast decomposition or lack synthetic accessibility. In this regard, nitronyl nitroxides are promising candidates for stable (bi-)radicals due to their high degree of spin delocalization along the O–N–C–N–O pentad unit. Unfortunately, they are limited to electron-rich systems so far. To overcome this limitation, we developed a synthetic procedure for the twofold spin decoration of electron-poor chromophores (Ered = −1158 mV) with nitronyl nitroxide radical moieties via selective deprotection/oxidation of the respective silylated precursors with boron fluoride and subsequent quenching with tetraethyl orthosilicate. Nitronyl nitroxide biradicals PBI–NN, IIn–NN, PhDPP–NN, ThDPP–NN, and FuDPP–NN bridged by perylene bisimide (PBI), isoindigo (IIn), and diketopyrrolopyrrole (DPP) pigment colorants were finally obtained as bench stable compounds after periodate oxidation with yields of 60–81%. The absorption spectral signatures of the chromophores remain preserved in the open shell state and match the ones of the pristine parent compounds, which allowed an a priori prediction of their optical properties. Consequently, we achieved twofold spin labeling while keeping the intrinsic properties of the electron deficient chromophores intact.

  @article{Rausch_2021, abstract = {Open shell organic molecules bearing π-cores are of great interest for optical, electronic, and magnetic applications but frequently suffer fast decomposition or lack synthetic accessibility. In this regard, nitronyl nitroxides are promising candidates for stable (bi-)radicals due to their high degree of spin delocalization along the O–N–C–N–O pentad unit. Unfortunately, they are limited to electron-rich systems so far. To overcome this limitation, we developed a synthetic procedure for the twofold spin decoration of electron-poor chromophores (Ered = −1158 mV) with nitronyl nitroxide radical moieties via selective deprotection/oxidation of the respective silylated precursors with boron fluoride and subsequent quenching with tetraethyl orthosilicate. Nitronyl nitroxide biradicals PBI–NN, IIn–NN, PhDPP–NN, ThDPP–NN, and FuDPP–NN bridged by perylene bisimide (PBI), isoindigo (IIn), and diketopyrrolopyrrole (DPP) pigment colorants were finally obtained as bench stable compounds after periodate oxidation with yields of 60–81%. The absorption spectral signatures of the chromophores remain preserved in the open shell state and match the ones of the pristine parent compounds, which allowed an a priori prediction of their optical properties. Consequently, we achieved twofold spin labeling while keeping the intrinsic properties of the electron deficient chromophores intact.}, author = {Rausch, Rodger and Krause, Ana-Maria and Krummenacher, Ivo and Braunschweig, Holger and Würthner, Frank}, journal = {J. Org. Chem.}, keywords = {myown}, month = {01}, number = 3, pages = {2447–2457}, publisher = {American Chemical Society ({ACS})}, title = {Nitronyl Nitroxide Bifunctionalized Electron-Poor Chromophores: Synthesis of Stable Dye Biradicals by Lewis Acid Promoted Desilylation}, volume = 86, year = 2021 }

  %0 Journal Article %1 Rausch_2021 %A Rausch, Rodger %A Krause, Ana-Maria %A Krummenacher, Ivo %A Braunschweig, Holger %A Würthner, Frank %D 2021 %I American Chemical Society (ACS) %J J. Org. Chem. %N 3 %P 2447--2457 %R 10.1021/acs.joc.0c02613 %T Nitronyl Nitroxide Bifunctionalized Electron-Poor Chromophores: Synthesis of Stable Dye Biradicals by Lewis Acid Promoted Desilylation %U https://doi.org/10.1021%2Facs.joc.0c02613 %V 86 %X Open shell organic molecules bearing π-cores are of great interest for optical, electronic, and magnetic applications but frequently suffer fast decomposition or lack synthetic accessibility. In this regard, nitronyl nitroxides are promising candidates for stable (bi-)radicals due to their high degree of spin delocalization along the O–N–C–N–O pentad unit. Unfortunately, they are limited to electron-rich systems so far. To overcome this limitation, we developed a synthetic procedure for the twofold spin decoration of electron-poor chromophores (Ered = −1158 mV) with nitronyl nitroxide radical moieties via selective deprotection/oxidation of the respective silylated precursors with boron fluoride and subsequent quenching with tetraethyl orthosilicate. Nitronyl nitroxide biradicals PBI–NN, IIn–NN, PhDPP–NN, ThDPP–NN, and FuDPP–NN bridged by perylene bisimide (PBI), isoindigo (IIn), and diketopyrrolopyrrole (DPP) pigment colorants were finally obtained as bench stable compounds after periodate oxidation with yields of 60–81%. The absorption spectral signatures of the chromophores remain preserved in the open shell state and match the ones of the pristine parent compounds, which allowed an a priori prediction of their optical properties. Consequently, we achieved twofold spin labeling while keeping the intrinsic properties of the electron deficient chromophores intact.
• Controlling Topography and Crystallinity of Melt Electrowritten Poly(e-Caprolactone) Fibers. Blum, Carina; Weichhold, Jan; Hochleitner, Gernot; Stepanenko, Vladimir; Würthner, Frank; Groll, Jürgen; Jungst, Tomasz. In 3D Printing and Additive Manufact., 8(5), pp. 315–321. 2021.
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  Melt electrowriting (MEW) is an aspiring 3D printing technology with an unprecedented resolution among fiber-based printing technologies. It offers the ability to direct-write predefined designs utilizing a jet of molten polymer to fabricate constructs composed of fibers with diameters of only a few micrometers. These dimensions enable unique construct properties. Poly(ɛ-caprolactone) (PCL), a semicrystalline polymer mainly used for biomedical and life science applications, is the most prominent material for MEW and exhibits excellent printing properties. Despite the wealth of melt electrowritten constructs that have been fabricated by MEW, a detailed investigation, especially regarding fiber analysis on a macro- and microlevel is still lacking. Hence, this study systematically examines the influence of process parameters such as spinneret diameter, feeding pressure, and collector velocity on the diameter and particularly the topography of PCL fibers and sheds light on how these parameters affect the mechanical properties and crystallinity. A correlation between the mechanical properties, crystallite size, and roughness of the deposited fiber, depending on the collector velocity and applied feeding pressure, is revealed. These findings are used to print constructs composed of fibers with different microtopography without affecting the fiber diameter and thus the macroscopic assembly of the printed constructs.

  @article{2021, abstract = {Melt electrowriting (MEW) is an aspiring 3D printing technology with an unprecedented resolution among fiber-based printing technologies. It offers the ability to direct-write predefined designs utilizing a jet of molten polymer to fabricate constructs composed of fibers with diameters of only a few micrometers. These dimensions enable unique construct properties. Poly(ɛ-caprolactone) (PCL), a semicrystalline polymer mainly used for biomedical and life science applications, is the most prominent material for MEW and exhibits excellent printing properties. Despite the wealth of melt electrowritten constructs that have been fabricated by MEW, a detailed investigation, especially regarding fiber analysis on a macro- and microlevel is still lacking. Hence, this study systematically examines the influence of process parameters such as spinneret diameter, feeding pressure, and collector velocity on the diameter and particularly the topography of PCL fibers and sheds light on how these parameters affect the mechanical properties and crystallinity. A correlation between the mechanical properties, crystallite size, and roughness of the deposited fiber, depending on the collector velocity and applied feeding pressure, is revealed. These findings are used to print constructs composed of fibers with different microtopography without affecting the fiber diameter and thus the macroscopic assembly of the printed constructs.}, author = {Blum, Carina and Weichhold, Jan and Hochleitner, Gernot and Stepanenko, Vladimir and Würthner, Frank and Groll, Jürgen and Jungst, Tomasz}, journal = {3D Printing and Additive Manufact.}, keywords = {myown}, month = 10, number = 5, pages = {315–321}, publisher = {Mary Ann Liebert Inc}, title = {Controlling Topography and Crystallinity of Melt Electrowritten Poly(e-Caprolactone) Fibers}, volume = 8, year = 2021 }

  %0 Journal Article %1 2021 %A Blum, Carina %A Weichhold, Jan %A Hochleitner, Gernot %A Stepanenko, Vladimir %A Würthner, Frank %A Groll, Jürgen %A Jungst, Tomasz %D 2021 %I Mary Ann Liebert Inc %J 3D Printing and Additive Manufact. %N 5 %P 315--321 %R 10.1089/3dp.2020.0290 %T Controlling Topography and Crystallinity of Melt Electrowritten Poly(e-Caprolactone) Fibers %U https://doi.org/10.1089%2F3dp.2020.0290 %V 8 %X Melt electrowriting (MEW) is an aspiring 3D printing technology with an unprecedented resolution among fiber-based printing technologies. It offers the ability to direct-write predefined designs utilizing a jet of molten polymer to fabricate constructs composed of fibers with diameters of only a few micrometers. These dimensions enable unique construct properties. Poly(ɛ-caprolactone) (PCL), a semicrystalline polymer mainly used for biomedical and life science applications, is the most prominent material for MEW and exhibits excellent printing properties. Despite the wealth of melt electrowritten constructs that have been fabricated by MEW, a detailed investigation, especially regarding fiber analysis on a macro- and microlevel is still lacking. Hence, this study systematically examines the influence of process parameters such as spinneret diameter, feeding pressure, and collector velocity on the diameter and particularly the topography of PCL fibers and sheds light on how these parameters affect the mechanical properties and crystallinity. A correlation between the mechanical properties, crystallite size, and roughness of the deposited fiber, depending on the collector velocity and applied feeding pressure, is revealed. These findings are used to print constructs composed of fibers with different microtopography without affecting the fiber diameter and thus the macroscopic assembly of the printed constructs.
• Charge-Delocalized State and Coherent Vibrational Dynamics in Rigid PBI H-Aggregates. Kang, Seongsoo; Kim, Taeyeon; Hong, Yongseok; Würthner, Frank; Kim, Dongho. In J. Am. Chem. Soc., 143(26), pp. 9825–9833. 2021.
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  Herein, the ultrafast photoinduced dynamics and vibrational coherences for two perylenebisimide (PBI) H-aggregates showcase the formation of the excimer state and the delocalized radical anion state in the excited state, respectively. Using femtosecond transient absorption (fs-TA) and time-resolved impulsive stimulated Raman scattering (TR-ISRS) measurements, we unveiled excited-state dynamics of PBI H-aggregates in two aspects: (1) the intermolecular interactions between PBI units in H-aggregates induce the formation of new excited states, excimer and delocalized radical anion states, and (2) the intermolecular out-of-plane along the aggregate axis and the PBI core C═C stretch Raman modes can be a crucial indicator to understand the coherent exciton dynamics in H-aggregates. Notably, those excited-state Raman modes showed stationary peak positions during the excited-state dynamics. TR-ISRS analysis provides insights into the excited-state vibrational coherences concerning the formation of the excimer and charge-delocalized state in each aggregate system.

  @article{Kang_2021, abstract = {Herein, the ultrafast photoinduced dynamics and vibrational coherences for two perylenebisimide (PBI) H-aggregates showcase the formation of the excimer state and the delocalized radical anion state in the excited state, respectively. Using femtosecond transient absorption (fs-TA) and time-resolved impulsive stimulated Raman scattering (TR-ISRS) measurements, we unveiled excited-state dynamics of PBI H-aggregates in two aspects: (1) the intermolecular interactions between PBI units in H-aggregates induce the formation of new excited states, excimer and delocalized radical anion states, and (2) the intermolecular out-of-plane along the aggregate axis and the PBI core C═C stretch Raman modes can be a crucial indicator to understand the coherent exciton dynamics in H-aggregates. Notably, those excited-state Raman modes showed stationary peak positions during the excited-state dynamics. TR-ISRS analysis provides insights into the excited-state vibrational coherences concerning the formation of the excimer and charge-delocalized state in each aggregate system.}, author = {Kang, Seongsoo and Kim, Taeyeon and Hong, Yongseok and Würthner, Frank and Kim, Dongho}, journal = {J. Am. Chem. Soc.}, keywords = {myown}, month = {06}, number = 26, pages = {9825–9833}, publisher = {American Chemical Society ({ACS})}, title = {Charge-Delocalized State and Coherent Vibrational Dynamics in Rigid PBI H-Aggregates}, volume = 143, year = 2021 }

  %0 Journal Article %1 Kang_2021 %A Kang, Seongsoo %A Kim, Taeyeon %A Hong, Yongseok %A Würthner, Frank %A Kim, Dongho %D 2021 %I American Chemical Society (ACS) %J J. Am. Chem. Soc. %N 26 %P 9825--9833 %R 10.1021/jacs.1c03276 %T Charge-Delocalized State and Coherent Vibrational Dynamics in Rigid PBI H-Aggregates %U https://doi.org/10.1021%2Fjacs.1c03276 %V 143 %X Herein, the ultrafast photoinduced dynamics and vibrational coherences for two perylenebisimide (PBI) H-aggregates showcase the formation of the excimer state and the delocalized radical anion state in the excited state, respectively. Using femtosecond transient absorption (fs-TA) and time-resolved impulsive stimulated Raman scattering (TR-ISRS) measurements, we unveiled excited-state dynamics of PBI H-aggregates in two aspects: (1) the intermolecular interactions between PBI units in H-aggregates induce the formation of new excited states, excimer and delocalized radical anion states, and (2) the intermolecular out-of-plane along the aggregate axis and the PBI core C═C stretch Raman modes can be a crucial indicator to understand the coherent exciton dynamics in H-aggregates. Notably, those excited-state Raman modes showed stationary peak positions during the excited-state dynamics. TR-ISRS analysis provides insights into the excited-state vibrational coherences concerning the formation of the excimer and charge-delocalized state in each aggregate system.
• Coherent two-dimensional electronic spectroelectrochemistry. Heitmüller, Julia; Eckstein, Klaus; Renner, Rebecca; Stolte, Matthias; Hertel, Tobias; Würthner, Frank; Brixner, Tobias. In Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, p. 119567. 2021.
  • [ Abstract ]
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  We report the development of a new spectroscopic scheme, coherent two-dimensional (2D) electronic spectroelectrochemistry. Conventional 2D electronic spectroscopy has become well established to investigate molecular energy transfer, charge transfer, or structural dynamics with femtosecond time resolution following electronic excitation, providing frequency resolution for both the excitation and the detection step. Here we combine this method with electrochemistry in a flow cell. Thus we have established access to the dynamics of various oxidized and reduced molecular species in solution. We investigate the photophysics of a tetraphenoxy-substituted perylene bisimide dye and its reduced species as a proof of principle and find substantially different dynamics for the neutral and the twofold reduced compound. The electrochemical flow cell is furthermore applied in conventional transient absorption spectroscopy and photoluminescence spectroscopies as an application in different setups.

  @article{Heitm_ller_2021, abstract = {We report the development of a new spectroscopic scheme, coherent two-dimensional (2D) electronic spectroelectrochemistry. Conventional 2D electronic spectroscopy has become well established to investigate molecular energy transfer, charge transfer, or structural dynamics with femtosecond time resolution following electronic excitation, providing frequency resolution for both the excitation and the detection step. Here we combine this method with electrochemistry in a flow cell. Thus we have established access to the dynamics of various oxidized and reduced molecular species in solution. We investigate the photophysics of a tetraphenoxy-substituted perylene bisimide dye and its reduced species as a proof of principle and find substantially different dynamics for the neutral and the twofold reduced compound. The electrochemical flow cell is furthermore applied in conventional transient absorption spectroscopy and photoluminescence spectroscopies as an application in different setups.}, author = {Heitmüller, Julia and Eckstein, Klaus and Renner, Rebecca and Stolte, Matthias and Hertel, Tobias and Würthner, Frank and Brixner, Tobias}, journal = {Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy}, keywords = {myown}, month = {02}, pages = 119567, publisher = {Elsevier {BV}}, title = {Coherent two-dimensional electronic spectroelectrochemistry}, year = 2021 }

  %0 Journal Article %1 Heitm_ller_2021 %A Heitmüller, Julia %A Eckstein, Klaus %A Renner, Rebecca %A Stolte, Matthias %A Hertel, Tobias %A Würthner, Frank %A Brixner, Tobias %D 2021 %I Elsevier BV %J Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy %P 119567 %R 10.1016/j.saa.2021.119567 %T Coherent two-dimensional electronic spectroelectrochemistry %U https://doi.org/10.1016%2Fj.saa.2021.119567 %X We report the development of a new spectroscopic scheme, coherent two-dimensional (2D) electronic spectroelectrochemistry. Conventional 2D electronic spectroscopy has become well established to investigate molecular energy transfer, charge transfer, or structural dynamics with femtosecond time resolution following electronic excitation, providing frequency resolution for both the excitation and the detection step. Here we combine this method with electrochemistry in a flow cell. Thus we have established access to the dynamics of various oxidized and reduced molecular species in solution. We investigate the photophysics of a tetraphenoxy-substituted perylene bisimide dye and its reduced species as a proof of principle and find substantially different dynamics for the neutral and the twofold reduced compound. The electrochemical flow cell is furthermore applied in conventional transient absorption spectroscopy and photoluminescence spectroscopies as an application in different setups.
• Structure-Activity Relationship for Di- up to Tetranuclear Macrocyclic Ruthenium Catalysts in Homogeneous Water Oxidation. Schindler, Dorothee; Meza-Chincha, Ana-Lucia; Roth, Maximilian; Würthner, Frank. In Chemistry – A European Journal, 27(68), pp. 16938–16946. 2021.
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  Two di- and tetranuclear Ru(bda) (bda: 2,2′-bipyridine-6,6′-dicarboxylate) macrocyclic complexes were synthesized and their catalytic activities in chemical and photochemical water oxidation investigated in a comparative manner to our previously reported trinuclear congener. Our studies have shown that the catalytic activities of this homologous series of multinuclear Ru(bda) macrocycles in homogeneous water oxidation are dependent on their size, exhibiting highest efficiencies for the largest tetranuclear catalyst. The turnover frequencies (TOFs) have increased from di- to tetranuclear macrocycles not only per catalyst molecule but more importantly also per Ru unit with TOF of 6 s−1 to 8.7 s−1 and 10.5 s−1 in chemical and 0.6 s−1 to 3.3 s−1 and 5.8 s−1 in photochemical water oxidation per Ru unit, respectively. Thus, for the first time, a clear structure–activity relationship could be established for this novel class of macrocyclic water oxidation catalysts.

  @article{Schindler_2021, abstract = {Two di- and tetranuclear Ru(bda) (bda: 2,2′-bipyridine-6,6′-dicarboxylate) macrocyclic complexes were synthesized and their catalytic activities in chemical and photochemical water oxidation investigated in a comparative manner to our previously reported trinuclear congener. Our studies have shown that the catalytic activities of this homologous series of multinuclear Ru(bda) macrocycles in homogeneous water oxidation are dependent on their size, exhibiting highest efficiencies for the largest tetranuclear catalyst. The turnover frequencies (TOFs) have increased from di- to tetranuclear macrocycles not only per catalyst molecule but more importantly also per Ru unit with TOF of 6 s−1 to 8.7 s−1 and 10.5 s−1 in chemical and 0.6 s−1 to 3.3 s−1 and 5.8 s−1 in photochemical water oxidation per Ru unit, respectively. Thus, for the first time, a clear structure–activity relationship could be established for this novel class of macrocyclic water oxidation catalysts.}, author = {Schindler, Dorothee and Meza-Chincha, Ana-Lucia and Roth, Maximilian and Würthner, Frank}, journal = {Chemistry – A European Journal}, keywords = {myown}, month = {05}, number = 68, pages = {16938–16946}, publisher = {Wiley}, title = {Structure-Activity Relationship for Di- up to Tetranuclear Macrocyclic Ruthenium Catalysts in Homogeneous Water Oxidation}, volume = 27, year = 2021 }

  %0 Journal Article %1 Schindler_2021 %A Schindler, Dorothee %A Meza-Chincha, Ana-Lucia %A Roth, Maximilian %A Würthner, Frank %D 2021 %I Wiley %J Chemistry – A European Journal %N 68 %P 16938--16946 %R 10.1002/chem.202100549 %T Structure-Activity Relationship for Di- up to Tetranuclear Macrocyclic Ruthenium Catalysts in Homogeneous Water Oxidation %U https://doi.org/10.1002%2Fchem.202100549 %V 27 %X Two di- and tetranuclear Ru(bda) (bda: 2,2′-bipyridine-6,6′-dicarboxylate) macrocyclic complexes were synthesized and their catalytic activities in chemical and photochemical water oxidation investigated in a comparative manner to our previously reported trinuclear congener. Our studies have shown that the catalytic activities of this homologous series of multinuclear Ru(bda) macrocycles in homogeneous water oxidation are dependent on their size, exhibiting highest efficiencies for the largest tetranuclear catalyst. The turnover frequencies (TOFs) have increased from di- to tetranuclear macrocycles not only per catalyst molecule but more importantly also per Ru unit with TOF of 6 s−1 to 8.7 s−1 and 10.5 s−1 in chemical and 0.6 s−1 to 3.3 s−1 and 5.8 s−1 in photochemical water oxidation per Ru unit, respectively. Thus, for the first time, a clear structure–activity relationship could be established for this novel class of macrocyclic water oxidation catalysts.
• Macrocyclic Donor-Acceptor Dyads Composed of a Perylene Bisimide Surrounded by Oligothiophene Bridges. Bold, Kevin; Stolte, Matthias; Shoyama, Kazutaka; Holzapfel, Marco; Schmiedel, Alexander; Lambert, Christoph; Würthner, Frank. In Angew. Chem. Int. Ed., 61(1). 2021.
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  Two macrocyclic architectures comprising oligothiophene strands that connect the imide positions of a perylene bisimide (PBI) have been synthesized via a platinum-mediated cross coupling strategy. The crystal structure of the double bridged PBI reveals all syn- arranged thiophene units which completely enclose the planar PBI chromophore via a 12-membered ring. The target structures were characterized by steady-state UV/Vis absorption, fluorescence and transient absorption spectroscopy, as well as cyclic and differential pulse voltammetry. Both donor-acceptor dyads show ultrafast Förster Resonance Energy Transfer (FRET) and photoinduced electron transfer, thereby leading to extremely low fluorescence quantum yields even in the lowest polarity cyclohexane solvent.

  @article{Bold_2021, abstract = {Two macrocyclic architectures comprising oligothiophene strands that connect the imide positions of a perylene bisimide (PBI) have been synthesized via a platinum-mediated cross coupling strategy. The crystal structure of the double bridged PBI reveals all syn- arranged thiophene units which completely enclose the planar PBI chromophore via a 12-membered ring. The target structures were characterized by steady-state UV/Vis absorption, fluorescence and transient absorption spectroscopy, as well as cyclic and differential pulse voltammetry. Both donor-acceptor dyads show ultrafast Förster Resonance Energy Transfer (FRET) and photoinduced electron transfer, thereby leading to extremely low fluorescence quantum yields even in the lowest polarity cyclohexane solvent.}, author = {Bold, Kevin and Stolte, Matthias and Shoyama, Kazutaka and Holzapfel, Marco and Schmiedel, Alexander and Lambert, Christoph and Würthner, Frank}, journal = {Angew. Chem. Int. Ed.}, keywords = {myown}, month = 10, number = 1, publisher = {Wiley}, title = {Macrocyclic Donor-Acceptor Dyads Composed of a Perylene Bisimide Surrounded by Oligothiophene Bridges}, volume = 61, year = 2021 }

  %0 Journal Article %1 Bold_2021 %A Bold, Kevin %A Stolte, Matthias %A Shoyama, Kazutaka %A Holzapfel, Marco %A Schmiedel, Alexander %A Lambert, Christoph %A Würthner, Frank %D 2021 %I Wiley %J Angew. Chem. Int. Ed. %N 1 %R 10.1002/anie.202113598 %T Macrocyclic Donor-Acceptor Dyads Composed of a Perylene Bisimide Surrounded by Oligothiophene Bridges %U https://doi.org/10.1002%2Fanie.202113598 %V 61 %X Two macrocyclic architectures comprising oligothiophene strands that connect the imide positions of a perylene bisimide (PBI) have been synthesized via a platinum-mediated cross coupling strategy. The crystal structure of the double bridged PBI reveals all syn- arranged thiophene units which completely enclose the planar PBI chromophore via a 12-membered ring. The target structures were characterized by steady-state UV/Vis absorption, fluorescence and transient absorption spectroscopy, as well as cyclic and differential pulse voltammetry. Both donor-acceptor dyads show ultrafast Förster Resonance Energy Transfer (FRET) and photoinduced electron transfer, thereby leading to extremely low fluorescence quantum yields even in the lowest polarity cyclohexane solvent.
• Surface-Promoted Evolution of Ru-bda Coordination Oligomers Boosts the Efficiency of Water Oxidation Molecular Anodes. Gil-Sepulcre, Marcos; Lindner, Joachim O.; Schindler, Dorothee; Velasco, Lucia; Moonshiram, Dooshaye; Rüdiger, Olaf; DeBeer, Serena; Stepanenko, Vladimir; Solano, Eduardo; Würthner, Frank; Llobet, Antoni. In J. Am. Chem. Soc., 143(30), pp. 11651–11661. 2021.
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  A new Ru oligomer of formula [RuII(bda-κ-N2O2)(4,4′-bpy)]10(4,4′-bpy), 10 (bda is [2,2′-bipyridine]-6,6′-dicarboxylate and 4,4′-bpy is 4,4′-bipyridine), was synthesized and thoroughly characterized with spectroscopic, X-ray, and electrochemical techniques. This oligomer exhibits strong affinity for graphitic materials through CH−π interactions and thus easily anchors on multiwalled carbon nanotubes (CNT), generating the molecular hybrid material 10@CNT. The latter acts as a water oxidation catalyst and converts to a new species, 10′(H2O)2@CNT, during the electrochemical oxygen evolution process involving solvation and ligand reorganization facilitated by the interactions of molecular Ru catalyst and the surface. This heterogeneous system has been shown to be a powerful and robust molecular hybrid anode for electrocatalytic water oxidation into molecular oxygen, achieving current densities in the range of 200 mA/cm2 at pH 7 under an applied potential of 1.45 V vs NHE. The remarkable long-term stability of this hybrid material during turnover is rationalized based on the supramolecular interaction of the catalyst with the graphitic surface.

  @article{Gil_Sepulcre_2021, abstract = {A new Ru oligomer of formula [RuII(bda-κ-N2O2)(4,4′-bpy)]10(4,4′-bpy), 10 (bda is [2,2′-bipyridine]-6,6′-dicarboxylate and 4,4′-bpy is 4,4′-bipyridine), was synthesized and thoroughly characterized with spectroscopic, X-ray, and electrochemical techniques. This oligomer exhibits strong affinity for graphitic materials through CH−π interactions and thus easily anchors on multiwalled carbon nanotubes (CNT), generating the molecular hybrid material 10@CNT. The latter acts as a water oxidation catalyst and converts to a new species, 10′(H2O)2@CNT, during the electrochemical oxygen evolution process involving solvation and ligand reorganization facilitated by the interactions of molecular Ru catalyst and the surface. This heterogeneous system has been shown to be a powerful and robust molecular hybrid anode for electrocatalytic water oxidation into molecular oxygen, achieving current densities in the range of 200 mA/cm2 at pH 7 under an applied potential of 1.45 V vs NHE. The remarkable long-term stability of this hybrid material during turnover is rationalized based on the supramolecular interaction of the catalyst with the graphitic surface.}, author = {Gil-Sepulcre, Marcos and Lindner, Joachim O. and Schindler, Dorothee and Velasco, Lucia and Moonshiram, Dooshaye and Rüdiger, Olaf and DeBeer, Serena and Stepanenko, Vladimir and Solano, Eduardo and Würthner, Frank and Llobet, Antoni}, journal = {J. Am. Chem. Soc.}, keywords = {myown}, month = {07}, number = 30, pages = {11651–11661}, publisher = {American Chemical Society ({ACS})}, title = {Surface-Promoted Evolution of Ru-bda Coordination Oligomers Boosts the Efficiency of Water Oxidation Molecular Anodes}, volume = 143, year = 2021 }

  %0 Journal Article %1 Gil_Sepulcre_2021 %A Gil-Sepulcre, Marcos %A Lindner, Joachim O. %A Schindler, Dorothee %A Velasco, Lucia %A Moonshiram, Dooshaye %A Rüdiger, Olaf %A DeBeer, Serena %A Stepanenko, Vladimir %A Solano, Eduardo %A Würthner, Frank %A Llobet, Antoni %D 2021 %I American Chemical Society (ACS) %J J. Am. Chem. Soc. %N 30 %P 11651--11661 %R 10.1021/jacs.1c04738 %T Surface-Promoted Evolution of Ru-bda Coordination Oligomers Boosts the Efficiency of Water Oxidation Molecular Anodes %U https://doi.org/10.1021%2Fjacs.1c04738 %V 143 %X A new Ru oligomer of formula [RuII(bda-κ-N2O2)(4,4′-bpy)]10(4,4′-bpy), 10 (bda is [2,2′-bipyridine]-6,6′-dicarboxylate and 4,4′-bpy is 4,4′-bipyridine), was synthesized and thoroughly characterized with spectroscopic, X-ray, and electrochemical techniques. This oligomer exhibits strong affinity for graphitic materials through CH−π interactions and thus easily anchors on multiwalled carbon nanotubes (CNT), generating the molecular hybrid material 10@CNT. The latter acts as a water oxidation catalyst and converts to a new species, 10′(H2O)2@CNT, during the electrochemical oxygen evolution process involving solvation and ligand reorganization facilitated by the interactions of molecular Ru catalyst and the surface. This heterogeneous system has been shown to be a powerful and robust molecular hybrid anode for electrocatalytic water oxidation into molecular oxygen, achieving current densities in the range of 200 mA/cm2 at pH 7 under an applied potential of 1.45 V vs NHE. The remarkable long-term stability of this hybrid material during turnover is rationalized based on the supramolecular interaction of the catalyst with the graphitic surface.
• Polymorphism in Squaraine Dye Aggregates by Self-Assembly Pathway Differentiation: Panchromatic Tubular Dye Nanorods versus J-Aggregate Nanosheets. Shen, Chia-An; Bialas, David; Hecht, Markus; Stepanenko, Vladimir; Sugiyasu, Kazunori; Würthner, Frank. In Angew. Chem. Int. Ed., 60(21), pp. 11949–11958. 2021.
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  A bis(squaraine) dye equipped with alkyl and oligoethyleneglycol chains was synthesized by connecting two dicyanomethylene substituted squaraine dyes with a phenylene spacer unit. The aggregation behavior of this bis(squaraine) was investigated in non‐polar toluene/tetrachloroethane (98:2) solvent mixture, which revealed competing cooperative self‐assembly pathways into two supramolecular polymorphs with entirely different packing structures and UV/Vis/NIR absorption properties. The self‐assembly pathway can be controlled by the cooling rate from a heated solution of the monomers. For both polymorphs, quasi‐equilibrium conditions between monomers and the respective aggregates can be established to derive thermodynamic parameters and insights into the self‐assembly mechanisms. AFM measurements revealed a nanosheet structure with a height of 2 nm for the thermodynamically more stable polymorph and a tubular nanorod structure with a helical pitch of 13 nm and a diameter of 5 nm for the kinetically favored polymorph. Together with wide angle X‐ray scattering measurements, packing models were derived: the thermodynamic polymorph consists of brick‐work type nanosheets that exhibit red‐shifted absorption bands as typical for J‐aggregates, while the nanorod polymorph consists of eight supramolecular polymer strands of the bis(squaraine) intertwined to form a chimney‐type tubular structure. The absorption of this aggregate covers a large spectral range from 550 to 875 nm, which cannot be rationalized by the conventional exciton theory. By applying the Essential States Model and considering intermolecular charge transfer, the aggregate spectrum was adequately reproduced, revealing that the broad absorption spectrum is due to pronounced donor‐acceptor overlap within the bis(squaraine) nanorods. The latter is also responsible for the pronounced bathochromic shift observed for the nanosheet structure as a result of the slip‐stacked arranged squaraine chromophores.

  @article{Shen_2021, abstract = {A bis(squaraine) dye equipped with alkyl and oligoethyleneglycol chains was synthesized by connecting two dicyanomethylene substituted squaraine dyes with a phenylene spacer unit. The aggregation behavior of this bis(squaraine) was investigated in non‐polar toluene/tetrachloroethane (98:2) solvent mixture, which revealed competing cooperative self‐assembly pathways into two supramolecular polymorphs with entirely different packing structures and UV/Vis/NIR absorption properties. The self‐assembly pathway can be controlled by the cooling rate from a heated solution of the monomers. For both polymorphs, quasi‐equilibrium conditions between monomers and the respective aggregates can be established to derive thermodynamic parameters and insights into the self‐assembly mechanisms. AFM measurements revealed a nanosheet structure with a height of 2 nm for the thermodynamically more stable polymorph and a tubular nanorod structure with a helical pitch of 13 nm and a diameter of 5 nm for the kinetically favored polymorph. Together with wide angle X‐ray scattering measurements, packing models were derived: the thermodynamic polymorph consists of brick‐work type nanosheets that exhibit red‐shifted absorption bands as typical for J‐aggregates, while the nanorod polymorph consists of eight supramolecular polymer strands of the bis(squaraine) intertwined to form a chimney‐type tubular structure. The absorption of this aggregate covers a large spectral range from 550 to 875 nm, which cannot be rationalized by the conventional exciton theory. By applying the Essential States Model and considering intermolecular charge transfer, the aggregate spectrum was adequately reproduced, revealing that the broad absorption spectrum is due to pronounced donor‐acceptor overlap within the bis(squaraine) nanorods. The latter is also responsible for the pronounced bathochromic shift observed for the nanosheet structure as a result of the slip‐stacked arranged squaraine chromophores.}, author = {Shen, Chia-An and Bialas, David and Hecht, Markus and Stepanenko, Vladimir and Sugiyasu, Kazunori and Würthner, Frank}, journal = {Angew. Chem. Int. Ed.}, keywords = {myown}, month = {05}, number = 21, pages = {11949–11958}, publisher = {Wiley}, title = {Polymorphism in Squaraine Dye Aggregates by Self-Assembly Pathway Differentiation: Panchromatic Tubular Dye Nanorods versus J-Aggregate Nanosheets}, volume = 60, year = 2021 }

  %0 Journal Article %1 Shen_2021 %A Shen, Chia-An %A Bialas, David %A Hecht, Markus %A Stepanenko, Vladimir %A Sugiyasu, Kazunori %A Würthner, Frank %D 2021 %I Wiley %J Angew. Chem. Int. Ed. %N 21 %P 11949--11958 %R 10.1002/anie.202102183 %T Polymorphism in Squaraine Dye Aggregates by Self-Assembly Pathway Differentiation: Panchromatic Tubular Dye Nanorods versus J-Aggregate Nanosheets %U https://doi.org/10.1002%2Fanie.202102183 %V 60 %X A bis(squaraine) dye equipped with alkyl and oligoethyleneglycol chains was synthesized by connecting two dicyanomethylene substituted squaraine dyes with a phenylene spacer unit. The aggregation behavior of this bis(squaraine) was investigated in non‐polar toluene/tetrachloroethane (98:2) solvent mixture, which revealed competing cooperative self‐assembly pathways into two supramolecular polymorphs with entirely different packing structures and UV/Vis/NIR absorption properties. The self‐assembly pathway can be controlled by the cooling rate from a heated solution of the monomers. For both polymorphs, quasi‐equilibrium conditions between monomers and the respective aggregates can be established to derive thermodynamic parameters and insights into the self‐assembly mechanisms. AFM measurements revealed a nanosheet structure with a height of 2 nm for the thermodynamically more stable polymorph and a tubular nanorod structure with a helical pitch of 13 nm and a diameter of 5 nm for the kinetically favored polymorph. Together with wide angle X‐ray scattering measurements, packing models were derived: the thermodynamic polymorph consists of brick‐work type nanosheets that exhibit red‐shifted absorption bands as typical for J‐aggregates, while the nanorod polymorph consists of eight supramolecular polymer strands of the bis(squaraine) intertwined to form a chimney‐type tubular structure. The absorption of this aggregate covers a large spectral range from 550 to 875 nm, which cannot be rationalized by the conventional exciton theory. By applying the Essential States Model and considering intermolecular charge transfer, the aggregate spectrum was adequately reproduced, revealing that the broad absorption spectrum is due to pronounced donor‐acceptor overlap within the bis(squaraine) nanorods. The latter is also responsible for the pronounced bathochromic shift observed for the nanosheet structure as a result of the slip‐stacked arranged squaraine chromophores.
• Folding and fluorescence enhancement with strong odd–even effect for a series of merocyanine dye oligomers. Hu, Xiaobo; Schulz, Alexander; Lindner, Joachim O.; Grüne, Matthias; Bialas, David; Würthner, Frank. In Chem. Sci., 12(24), pp. 8342–8352. 2021.
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  A series of merocyanine (MC) oligomers with a varying number of chromophores from two to six has been synthesized via a peptide synthesis strategy. Solvent-dependent UV/vis spectroscopic studies reveal folding processes for the MC oligomers driven by strong dipole–dipole interactions resulting in well-defined π-stacks with antiparallel orientation of the dyes. Whilst even-numbered tetramer 4 and hexamer 6 only show partial folding into dimeric units, odd-numbered trimer 3 and pentamer 5 fold into π-stacks of three and five MC units upon decreasing solvent polarity. In-depth 2D NMR studies provided insight into the supramolecular structure. For trimer 3, an NMR structure could be generated revealing the presence of a well-defined triple π-stack in the folded state. Concomitant with folding, the fluorescence quantum yield is increased for all MC oligomers in comparison to the single chromophore. Based on radiative and non-radiative decay rates, this fluorescence enhancement can be attributed to the rigidification of the chromophores within the π-stacks that affords a pronounced decrease of the non-radiative decay rates. Theoretical investigations for the double and triple dye stacks based on time-dependent density functional theory (TD-DFT) calculations indicate for trimer 3 a pronounced mixing of Frenkel and charge transfer (CT) states. This leads to significant deviations from the predictions obtained by the molecular exciton theory which only accounts for the Coulomb interaction between the transition dipole moments of the chromophores.

  @article{D1SC01678D, abstract = {A series of merocyanine (MC) oligomers with a varying number of chromophores from two to six has been synthesized via a peptide synthesis strategy. Solvent-dependent UV/vis spectroscopic studies reveal folding processes for the MC oligomers driven by strong dipole–dipole interactions resulting in well-defined π-stacks with antiparallel orientation of the dyes. Whilst even-numbered tetramer 4 and hexamer 6 only show partial folding into dimeric units{,} odd-numbered trimer 3 and pentamer 5 fold into π-stacks of three and five MC units upon decreasing solvent polarity. In-depth 2D NMR studies provided insight into the supramolecular structure. For trimer 3{,} an NMR structure could be generated revealing the presence of a well-defined triple π-stack in the folded state. Concomitant with folding{,} the fluorescence quantum yield is increased for all MC oligomers in comparison to the single chromophore. Based on radiative and non-radiative decay rates{,} this fluorescence enhancement can be attributed to the rigidification of the chromophores within the π-stacks that affords a pronounced decrease of the non-radiative decay rates. Theoretical investigations for the double and triple dye stacks based on time-dependent density functional theory (TD-DFT) calculations indicate for trimer 3 a pronounced mixing of Frenkel and charge transfer (CT) states. This leads to significant deviations from the predictions obtained by the molecular exciton theory which only accounts for the Coulomb interaction between the transition dipole moments of the chromophores.}, author = {Hu, Xiaobo and Schulz, Alexander and Lindner, Joachim O. and Grüne, Matthias and Bialas, David and Würthner, Frank}, journal = {Chem. Sci.}, keywords = {myown}, number = 24, pages = {8342-8352}, publisher = {The Royal Society of Chemistry}, title = {Folding and fluorescence enhancement with strong odd–even effect for a series of merocyanine dye oligomers}, volume = 12, year = 2021 }

  %0 Journal Article %1 D1SC01678D %A Hu, Xiaobo %A Schulz, Alexander %A Lindner, Joachim O. %A Grüne, Matthias %A Bialas, David %A Würthner, Frank %D 2021 %I The Royal Society of Chemistry %J Chem. Sci. %N 24 %P 8342-8352 %R 10.1039/D1SC01678D %T Folding and fluorescence enhancement with strong odd–even effect for a series of merocyanine dye oligomers %U http://dx.doi.org/10.1039/D1SC01678D %V 12 %X A series of merocyanine (MC) oligomers with a varying number of chromophores from two to six has been synthesized via a peptide synthesis strategy. Solvent-dependent UV/vis spectroscopic studies reveal folding processes for the MC oligomers driven by strong dipole–dipole interactions resulting in well-defined π-stacks with antiparallel orientation of the dyes. Whilst even-numbered tetramer 4 and hexamer 6 only show partial folding into dimeric units, odd-numbered trimer 3 and pentamer 5 fold into π-stacks of three and five MC units upon decreasing solvent polarity. In-depth 2D NMR studies provided insight into the supramolecular structure. For trimer 3, an NMR structure could be generated revealing the presence of a well-defined triple π-stack in the folded state. Concomitant with folding, the fluorescence quantum yield is increased for all MC oligomers in comparison to the single chromophore. Based on radiative and non-radiative decay rates, this fluorescence enhancement can be attributed to the rigidification of the chromophores within the π-stacks that affords a pronounced decrease of the non-radiative decay rates. Theoretical investigations for the double and triple dye stacks based on time-dependent density functional theory (TD-DFT) calculations indicate for trimer 3 a pronounced mixing of Frenkel and charge transfer (CT) states. This leads to significant deviations from the predictions obtained by the molecular exciton theory which only accounts for the Coulomb interaction between the transition dipole moments of the chromophores.
• An Efficient Narrowband Near-Infrared at 1040nm Organic Photodetector Realized by Intermolecular Charge Transfer Mediated Coupling Based on a Squaraine Dye. Kim, Jin Hong; Liess, Andreas; Stolte, Matthias; Krause, Ana-Maria; Stepanenko, Vladimir; Zhong, Chuwei; Bialas, David; Spano, Frank; Würthner, Frank. In Adv. Mater., 33(26), p. 2100582. 2021.
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  A highly sensitive short-wave infrared (SWIR, λ > 1000 nm) organic photodiode (OPD) is described based on a well-organized nanocrystalline bulk-heterojunction (BHJ) active layer composed of a dicyanovinyl-functionalized squaraine dye (SQ-H) donor material in combination with PC61BM. Through thermal annealing, dipolar SQ-H chromophores self-assemble in a nanoscale structure with intermolecular charge transfer mediated coupling, resulting in a redshifted and narrow absorption band at 1040 nm as well as enhanced charge carrier mobility. The optimized OPD exhibits an external quantum efficiency (EQE) of 12.3% and a full-width at half-maximum of only 85 nm (815 cm−1) at 1050 nm under 0 V, which is the first efficient SWIR OPD based on J-type aggregates. Photoplethysmography application for heart-rate monitoring is successfully demonstrated on flexible substrates without applying reverse bias, indicating the potential of OPDs based on short-range coupled dye aggregates for low-power operating wearable applications.

  @article{Kim_2021, abstract = {A highly sensitive short-wave infrared (SWIR, λ > 1000 nm) organic photodiode (OPD) is described based on a well-organized nanocrystalline bulk-heterojunction (BHJ) active layer composed of a dicyanovinyl-functionalized squaraine dye (SQ-H) donor material in combination with PC61BM. Through thermal annealing, dipolar SQ-H chromophores self-assemble in a nanoscale structure with intermolecular charge transfer mediated coupling, resulting in a redshifted and narrow absorption band at 1040 nm as well as enhanced charge carrier mobility. The optimized OPD exhibits an external quantum efficiency (EQE) of 12.3% and a full-width at half-maximum of only 85 nm (815 cm−1) at 1050 nm under 0 V, which is the first efficient SWIR OPD based on J-type aggregates. Photoplethysmography application for heart-rate monitoring is successfully demonstrated on flexible substrates without applying reverse bias, indicating the potential of OPDs based on short-range coupled dye aggregates for low-power operating wearable applications.}, author = {Kim, Jin Hong and Liess, Andreas and Stolte, Matthias and Krause, Ana-Maria and Stepanenko, Vladimir and Zhong, Chuwei and Bialas, David and Spano, Frank and Würthner, Frank}, journal = {Adv. Mater.}, keywords = {myown}, month = {05}, number = 26, pages = 2100582, publisher = {Wiley}, title = {An Efficient Narrowband Near-Infrared at 1040nm Organic Photodetector Realized by Intermolecular Charge Transfer Mediated Coupling Based on a Squaraine Dye}, volume = 33, year = 2021 }

  %0 Journal Article %1 Kim_2021 %A Kim, Jin Hong %A Liess, Andreas %A Stolte, Matthias %A Krause, Ana-Maria %A Stepanenko, Vladimir %A Zhong, Chuwei %A Bialas, David %A Spano, Frank %A Würthner, Frank %D 2021 %I Wiley %J Adv. Mater. %N 26 %P 2100582 %R 10.1002/adma.202100582 %T An Efficient Narrowband Near-Infrared at 1040nm Organic Photodetector Realized by Intermolecular Charge Transfer Mediated Coupling Based on a Squaraine Dye %U https://doi.org/10.1002%2Fadma.202100582 %V 33 %X A highly sensitive short-wave infrared (SWIR, λ > 1000 nm) organic photodiode (OPD) is described based on a well-organized nanocrystalline bulk-heterojunction (BHJ) active layer composed of a dicyanovinyl-functionalized squaraine dye (SQ-H) donor material in combination with PC61BM. Through thermal annealing, dipolar SQ-H chromophores self-assemble in a nanoscale structure with intermolecular charge transfer mediated coupling, resulting in a redshifted and narrow absorption band at 1040 nm as well as enhanced charge carrier mobility. The optimized OPD exhibits an external quantum efficiency (EQE) of 12.3% and a full-width at half-maximum of only 85 nm (815 cm−1) at 1050 nm under 0 V, which is the first efficient SWIR OPD based on J-type aggregates. Photoplethysmography application for heart-rate monitoring is successfully demonstrated on flexible substrates without applying reverse bias, indicating the potential of OPDs based on short-range coupled dye aggregates for low-power operating wearable applications.
• Semitransparent Layers of Social Self-Sorting Merocyanine Dyes for Ultranarrow Bandwidth Organic Photodiodes. Schembri, Tim; Kim, Jin Hong; Liess, Andreas; Stepanenko, Vladimir; Stolte, Matthias; Würthner, Frank. In Advanced Optical Materials, 9(15), p. 2100213. 2021.
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  Two dipolar merocyanines consisting of the same π-conjugated chromophore but different alkyl substituents adopt very different packing arrangements in their respective solid state with either H- or J-type exciton coupling, leading to ultranarrow absorption bands at 477 and 750 nm, respectively, due to exchange narrowing. The social self-sorting behavior of these push-pull chromophores in their mixed thin films is evaluated and the impact on morphology as well as opto-electronical properties is determined. The implementation of this well-tuned two-component material with tailored optical features allows to optimize planar heterojunction organic photodiodes with fullerene ​(C60) with either dual or single wavelength selectivity in the blue and NIR spectral range with ultranarrow bandwidths of only 11 nm (200 cm−1) and an external quantum efficiency of up to 18% at 754 nm under 0 V bias. The application of these photodiodes as low-power consuming heart rate monitors is demonstrated by a reflectance-mode photoplethysmography (PPG) sensor.

  @article{Schembri_2021, abstract = {Two dipolar merocyanines consisting of the same π-conjugated chromophore but different alkyl substituents adopt very different packing arrangements in their respective solid state with either H- or J-type exciton coupling, leading to ultranarrow absorption bands at 477 and 750 nm, respectively, due to exchange narrowing. The social self-sorting behavior of these push-pull chromophores in their mixed thin films is evaluated and the impact on morphology as well as opto-electronical properties is determined. The implementation of this well-tuned two-component material with tailored optical features allows to optimize planar heterojunction organic photodiodes with fullerene ​(C60) with either dual or single wavelength selectivity in the blue and NIR spectral range with ultranarrow bandwidths of only 11 nm (200 cm−1) and an external quantum efficiency of up to 18% at 754 nm under 0 V bias. The application of these photodiodes as low-power consuming heart rate monitors is demonstrated by a reflectance-mode photoplethysmography (PPG) sensor.}, author = {Schembri, Tim and Kim, Jin Hong and Liess, Andreas and Stepanenko, Vladimir and Stolte, Matthias and Würthner, Frank}, journal = {Advanced Optical Materials}, keywords = {myown}, month = {05}, number = 15, pages = 2100213, publisher = {Wiley}, title = {Semitransparent Layers of Social Self-Sorting Merocyanine Dyes for Ultranarrow Bandwidth Organic Photodiodes}, volume = 9, year = 2021 }

  %0 Journal Article %1 Schembri_2021 %A Schembri, Tim %A Kim, Jin Hong %A Liess, Andreas %A Stepanenko, Vladimir %A Stolte, Matthias %A Würthner, Frank %D 2021 %I Wiley %J Advanced Optical Materials %N 15 %P 2100213 %R 10.1002/adom.202100213 %T Semitransparent Layers of Social Self-Sorting Merocyanine Dyes for Ultranarrow Bandwidth Organic Photodiodes %U https://doi.org/10.1002%2Fadom.202100213 %V 9 %X Two dipolar merocyanines consisting of the same π-conjugated chromophore but different alkyl substituents adopt very different packing arrangements in their respective solid state with either H- or J-type exciton coupling, leading to ultranarrow absorption bands at 477 and 750 nm, respectively, due to exchange narrowing. The social self-sorting behavior of these push-pull chromophores in their mixed thin films is evaluated and the impact on morphology as well as opto-electronical properties is determined. The implementation of this well-tuned two-component material with tailored optical features allows to optimize planar heterojunction organic photodiodes with fullerene ​(C60) with either dual or single wavelength selectivity in the blue and NIR spectral range with ultranarrow bandwidths of only 11 nm (200 cm−1) and an external quantum efficiency of up to 18% at 754 nm under 0 V bias. The application of these photodiodes as low-power consuming heart rate monitors is demonstrated by a reflectance-mode photoplethysmography (PPG) sensor.
• Slip-Stacked J-Aggregate Materials for Organic Solar Cells and Photodetectors. Kim, Jin Hong; Schembri, Tim; Bialas, David; Stolte, Matthias; Würthner, Frank. In Adv. Mater., p. 2104678. 2021.
  • [ Abstract ]
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  Dye–dye interactions affect the optical and electronic properties in organic semiconductor films of light harvesting and detecting optoelectronic applications. This review elaborates how to tailor these properties of organic semiconductors for organic solar cells (OSCs) and organic photodiodes (OPDs). While these devices rely on similar materials, the demands for their optical properties are rather different, the former requiring a broad absorption spectrum spanning from the UV over visible up to the near-infrared region and the latter an ultra-narrow absorption spectrum at a specific, targeted wavelength. In order to design organic semiconductors satisfying these demands, fundamental insights on the relationship of optical properties are provided depending on molecular packing arrangement and the resultant electronic coupling thereof. Based on recent advancements in the theoretical understanding of intermolecular interactions between slip-stacked dyes, distinguishing classical J-aggregates with predominant long-range Coulomb coupling from charge transfer (CT)-mediated or -coupled J-aggregates, whose red-shifts are primarily governed by short-range orbital interactions, is suggested. Within this framework, the relationship between aggregate structure and functional properties of representative classes of dye aggregates is analyzed for the most advanced OSCs and wavelength-selective OPDs, providing important insights into the rational design of thin-film optoelectronic materials.

  @article{Kim_2021, abstract = {Dye–dye interactions affect the optical and electronic properties in organic semiconductor films of light harvesting and detecting optoelectronic applications. This review elaborates how to tailor these properties of organic semiconductors for organic solar cells (OSCs) and organic photodiodes (OPDs). While these devices rely on similar materials, the demands for their optical properties are rather different, the former requiring a broad absorption spectrum spanning from the UV over visible up to the near-infrared region and the latter an ultra-narrow absorption spectrum at a specific, targeted wavelength. In order to design organic semiconductors satisfying these demands, fundamental insights on the relationship of optical properties are provided depending on molecular packing arrangement and the resultant electronic coupling thereof. Based on recent advancements in the theoretical understanding of intermolecular interactions between slip-stacked dyes, distinguishing classical J-aggregates with predominant long-range Coulomb coupling from charge transfer (CT)-mediated or -coupled J-aggregates, whose red-shifts are primarily governed by short-range orbital interactions, is suggested. Within this framework, the relationship between aggregate structure and functional properties of representative classes of dye aggregates is analyzed for the most advanced OSCs and wavelength-selective OPDs, providing important insights into the rational design of thin-film optoelectronic materials.}, author = {Kim, Jin Hong and Schembri, Tim and Bialas, David and Stolte, Matthias and Würthner, Frank}, journal = {Adv. Mater.}, keywords = {myown}, month = 10, pages = 2104678, publisher = {Wiley}, title = {Slip-Stacked J-Aggregate Materials for Organic Solar Cells and Photodetectors}, year = 2021 }

  %0 Journal Article %1 Kim_2021 %A Kim, Jin Hong %A Schembri, Tim %A Bialas, David %A Stolte, Matthias %A Würthner, Frank %D 2021 %I Wiley %J Adv. Mater. %P 2104678 %R 10.1002/adma.202104678 %T Slip-Stacked J-Aggregate Materials for Organic Solar Cells and Photodetectors %U https://doi.org/10.1002%2Fadma.202104678 %X Dye–dye interactions affect the optical and electronic properties in organic semiconductor films of light harvesting and detecting optoelectronic applications. This review elaborates how to tailor these properties of organic semiconductors for organic solar cells (OSCs) and organic photodiodes (OPDs). While these devices rely on similar materials, the demands for their optical properties are rather different, the former requiring a broad absorption spectrum spanning from the UV over visible up to the near-infrared region and the latter an ultra-narrow absorption spectrum at a specific, targeted wavelength. In order to design organic semiconductors satisfying these demands, fundamental insights on the relationship of optical properties are provided depending on molecular packing arrangement and the resultant electronic coupling thereof. Based on recent advancements in the theoretical understanding of intermolecular interactions between slip-stacked dyes, distinguishing classical J-aggregates with predominant long-range Coulomb coupling from charge transfer (CT)-mediated or -coupled J-aggregates, whose red-shifts are primarily governed by short-range orbital interactions, is suggested. Within this framework, the relationship between aggregate structure and functional properties of representative classes of dye aggregates is analyzed for the most advanced OSCs and wavelength-selective OPDs, providing important insights into the rational design of thin-film optoelectronic materials.
• Chiral Perylene Bisimide Dyes by Interlocked Arene Substituents in the Bay Area. Renner, Rebecca; Mahlmeister, Bernhard; Anhalt, Olga; Stolte, Matthias; Würthner, Frank. In Chemistry A European Journal, 27(46), pp. 11997–12006. 2021.
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  A series of perylene bisimide (PBI) dyes bearing various aryl substituents in 1,6,7,12 bay positions has been synthesized by Suzuki cross-coupling reaction. These molecules exhibit an exceptionally large and conformationally fixed twist angle of the PBI π-core due to the high steric congestion imparted by the aryl substituents in bay positions. Single crystal X-ray analyses of phenyl-, naphthyl- and pyrenyl-functionalized PBIs reveal interlocked π-π-stacking motifs, leading to conformational chirality and the possibility for the isolation of enantiopure atropoisomers by semipreparative HPLC. The interlocked arrangement endows these molecules with substantial racemization barriers of about 120 kJ mol−1 for the tetraphenyl- and tetra-2-naphthyl-substituted derivatives, which is among the highest racemization barriers for axially chiral PBIs. Variable temperature NMR studies reveal the presence of a multitude of up to fourteen conformational isomers in solution that are interconverted via smaller activation barriers of about 65 kJ mol−1. The redox and optical properties of these core-twisted PBIs have been characterized by cyclic voltammetry, UV/Vis/NIR and fluorescence spectroscopy and their respective atropo-enantiomers were further characterized by circular dichroism (CD) and circular polarized luminescence (CPL) spectroscopy.

  @article{Renner_2021, abstract = {A series of perylene bisimide (PBI) dyes bearing various aryl substituents in 1,6,7,12 bay positions has been synthesized by Suzuki cross-coupling reaction. These molecules exhibit an exceptionally large and conformationally fixed twist angle of the PBI π-core due to the high steric congestion imparted by the aryl substituents in bay positions. Single crystal X-ray analyses of phenyl-, naphthyl- and pyrenyl-functionalized PBIs reveal interlocked π-π-stacking motifs, leading to conformational chirality and the possibility for the isolation of enantiopure atropoisomers by semipreparative HPLC. The interlocked arrangement endows these molecules with substantial racemization barriers of about 120 kJ mol−1 for the tetraphenyl- and tetra-2-naphthyl-substituted derivatives, which is among the highest racemization barriers for axially chiral PBIs. Variable temperature NMR studies reveal the presence of a multitude of up to fourteen conformational isomers in solution that are interconverted via smaller activation barriers of about 65 kJ mol−1. The redox and optical properties of these core-twisted PBIs have been characterized by cyclic voltammetry, UV/Vis/NIR and fluorescence spectroscopy and their respective atropo-enantiomers were further characterized by circular dichroism (CD) and circular polarized luminescence (CPL) spectroscopy.}, author = {Renner, Rebecca and Mahlmeister, Bernhard and Anhalt, Olga and Stolte, Matthias and Würthner, Frank}, journal = {Chemistry A European Journal}, keywords = {myown}, month = {07}, number = 46, pages = {11997–12006}, publisher = {Wiley}, title = {Chiral Perylene Bisimide Dyes by Interlocked Arene Substituents in the Bay Area}, volume = 27, year = 2021 }

  %0 Journal Article %1 Renner_2021 %A Renner, Rebecca %A Mahlmeister, Bernhard %A Anhalt, Olga %A Stolte, Matthias %A Würthner, Frank %D 2021 %I Wiley %J Chemistry A European Journal %N 46 %P 11997--12006 %R 10.1002/chem.202101877 %T Chiral Perylene Bisimide Dyes by Interlocked Arene Substituents in the Bay Area %U https://doi.org/10.1002%2Fchem.202101877 %V 27 %X A series of perylene bisimide (PBI) dyes bearing various aryl substituents in 1,6,7,12 bay positions has been synthesized by Suzuki cross-coupling reaction. These molecules exhibit an exceptionally large and conformationally fixed twist angle of the PBI π-core due to the high steric congestion imparted by the aryl substituents in bay positions. Single crystal X-ray analyses of phenyl-, naphthyl- and pyrenyl-functionalized PBIs reveal interlocked π-π-stacking motifs, leading to conformational chirality and the possibility for the isolation of enantiopure atropoisomers by semipreparative HPLC. The interlocked arrangement endows these molecules with substantial racemization barriers of about 120 kJ mol−1 for the tetraphenyl- and tetra-2-naphthyl-substituted derivatives, which is among the highest racemization barriers for axially chiral PBIs. Variable temperature NMR studies reveal the presence of a multitude of up to fourteen conformational isomers in solution that are interconverted via smaller activation barriers of about 65 kJ mol−1. The redox and optical properties of these core-twisted PBIs have been characterized by cyclic voltammetry, UV/Vis/NIR and fluorescence spectroscopy and their respective atropo-enantiomers were further characterized by circular dichroism (CD) and circular polarized luminescence (CPL) spectroscopy.
• Unusual Zig-Zag Effect in the Electrochemical Oxidation of Phenyl End-Capped a-Oligothiophenes. Bold, Kevin; Stolte, Matthias; Würthner, Frank. In Organic Materials, 03(02), pp. 119–127. 2021.
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  A series of phenyl end-capped α-oligothiophenes containing four to seven thiophene subunits (4T–7T) was synthesized utilizing palladium-catalyzed cross-coupling reactions. UV/Vis spectroscopic analysis revealed one broad absorption band that shifts bathochromically with increasing number of thiophene units. Structured emission spectra are observed with Stokes shift ν~4000 cm−1 and quantum yields of up to 53%. End-capping of the oligothiophene molecules by phenyl units does not only extend the effective conjugation but also prevents from α–α-homocoupling upon electrochemical oxidation. Accordingly, reversible redox waves are observed in cyclic voltammetry with up to four reversible one-electron processes for the two longer congeners. Analyses of the first two oxidation processes in the framework of multiredox systems provide insight into the stabilization or destabilization of polaronic and bipolaronic states. An unusual zig-zag trend for the first (and to a lesser extend second) oxidation process could be explained by the sterical encumbrance of solubilizing hexyl chains in 5T and 7T molecules which counteract the formation of a fully planar quinoidal oligothiophene backbone.

  @article{Bold_2021, abstract = {A series of phenyl end-capped α-oligothiophenes containing four to seven thiophene subunits (4T–7T) was synthesized utilizing palladium-catalyzed cross-coupling reactions. UV/Vis spectroscopic analysis revealed one broad absorption band that shifts bathochromically with increasing number of thiophene units. Structured emission spectra are observed with Stokes shift ν 4000 cm−1 and quantum yields of up to 53%. End-capping of the oligothiophene molecules by phenyl units does not only extend the effective conjugation but also prevents from α–α-homocoupling upon electrochemical oxidation. Accordingly, reversible redox waves are observed in cyclic voltammetry with up to four reversible one-electron processes for the two longer congeners. Analyses of the first two oxidation processes in the framework of multiredox systems provide insight into the stabilization or destabilization of polaronic and bipolaronic states. An unusual zig-zag trend for the first (and to a lesser extend second) oxidation process could be explained by the sterical encumbrance of solubilizing hexyl chains in 5T and 7T molecules which counteract the formation of a fully planar quinoidal oligothiophene backbone.}, author = {Bold, Kevin and Stolte, Matthias and Würthner, Frank}, journal = {Organic Materials}, keywords = {myown}, month = {04}, number = {02}, pages = {119–127}, publisher = {Georg Thieme Verlag {KG}}, title = {Unusual Zig-Zag Effect in the Electrochemical Oxidation of Phenyl End-Capped a-Oligothiophenes}, volume = {03}, year = 2021 }

  %0 Journal Article %1 Bold_2021 %A Bold, Kevin %A Stolte, Matthias %A Würthner, Frank %D 2021 %I Georg Thieme Verlag KG %J Organic Materials %N 02 %P 119--127 %R 10.1055/s-0041-1726089 %T Unusual Zig-Zag Effect in the Electrochemical Oxidation of Phenyl End-Capped a-Oligothiophenes %U https://doi.org/10.1055%2Fs-0041-1726089 %V 03 %X A series of phenyl end-capped α-oligothiophenes containing four to seven thiophene subunits (4T–7T) was synthesized utilizing palladium-catalyzed cross-coupling reactions. UV/Vis spectroscopic analysis revealed one broad absorption band that shifts bathochromically with increasing number of thiophene units. Structured emission spectra are observed with Stokes shift ν~4000 cm−1 and quantum yields of up to 53%. End-capping of the oligothiophene molecules by phenyl units does not only extend the effective conjugation but also prevents from α–α-homocoupling upon electrochemical oxidation. Accordingly, reversible redox waves are observed in cyclic voltammetry with up to four reversible one-electron processes for the two longer congeners. Analyses of the first two oxidation processes in the framework of multiredox systems provide insight into the stabilization or destabilization of polaronic and bipolaronic states. An unusual zig-zag trend for the first (and to a lesser extend second) oxidation process could be explained by the sterical encumbrance of solubilizing hexyl chains in 5T and 7T molecules which counteract the formation of a fully planar quinoidal oligothiophene backbone.
• Folding-induced Fluorescence Enhancement in a Series of Merocyanine Hetero-Folda-Trimers. Schulz, Alexander; Würthner, Frank. In Angew. Chem. Int. Ed., 61(2). 2021.
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  Many dyes suffer from fast non-radiative decaypathways, thereby showing only short-lived excited states andweak photoluminescence. Here we show a pronounced fluo-rescence enhancement for a weakly fluorescent merocyanine(MC) dye by being co-facially stacked to other dyes in hetero-folda-trimer architectures. By means of fluorescence spectros-copy (lifetime, quantum yield) the fluorescence enhancementwas explained by the rigidification of the emitting chromo-phore in the defined foldamer architecture and the presence ofa non-forbidden lowest exciton state in H-coupled hetero-aggregates. This folding-induced fluorescence enhancement(FIFE) for specific sequences ofp-stacked dyes points ata viable strategy toward improved fluorophores that relates tothe approach used by nature in the green fluorescent protein(GFP).

  @article{Schulz_2021, abstract = {Many dyes suffer from fast non-radiative decaypathways, thereby showing only short-lived excited states andweak photoluminescence. Here we show a pronounced fluo-rescence enhancement for a weakly fluorescent merocyanine(MC) dye by being co-facially stacked to other dyes in hetero-folda-trimer architectures. By means of fluorescence spectros-copy (lifetime, quantum yield) the fluorescence enhancementwas explained by the rigidification of the emitting chromo-phore in the defined foldamer architecture and the presence ofa non-forbidden lowest exciton state in H-coupled hetero-aggregates. This folding-induced fluorescence enhancement(FIFE) for specific sequences ofp-stacked dyes points ata viable strategy toward improved fluorophores that relates tothe approach used by nature in the green fluorescent protein(GFP).}, author = {Schulz, Alexander and Würthner, Frank}, journal = {Angew. Chem. Int. Ed.}, keywords = {myown}, month = 11, number = 2, publisher = {Wiley}, title = {Folding-induced Fluorescence Enhancement in a Series of Merocyanine Hetero-Folda-Trimers}, volume = 61, year = 2021 }

  %0 Journal Article %1 Schulz_2021 %A Schulz, Alexander %A Würthner, Frank %D 2021 %I Wiley %J Angew. Chem. Int. Ed. %N 2 %R 10.1002/anie.202114667 %T Folding-induced Fluorescence Enhancement in a Series of Merocyanine Hetero-Folda-Trimers %U https://doi.org/10.1002%2Fanie.202114667 %V 61 %X Many dyes suffer from fast non-radiative decaypathways, thereby showing only short-lived excited states andweak photoluminescence. Here we show a pronounced fluo-rescence enhancement for a weakly fluorescent merocyanine(MC) dye by being co-facially stacked to other dyes in hetero-folda-trimer architectures. By means of fluorescence spectros-copy (lifetime, quantum yield) the fluorescence enhancementwas explained by the rigidification of the emitting chromo-phore in the defined foldamer architecture and the presence ofa non-forbidden lowest exciton state in H-coupled hetero-aggregates. This folding-induced fluorescence enhancement(FIFE) for specific sequences ofp-stacked dyes points ata viable strategy toward improved fluorophores that relates tothe approach used by nature in the green fluorescent protein(GFP).
• Understanding the structural and charge transport property relationships for a variety of merocyanine single-crystals: a bottom up computational investigation. Gildemeister, Nora; Ricci, Gaetano; Böhner, Lukas; Neudörfl, Jörg M.; Hertel, Dirk; Würthner, Frank; Negri, Fabrizia; Meerholz, Klaus; Fazzi, Daniele. In J. Mater. Chem. C, 9(33), pp. 10851–10864. 2021.
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  Merocyanines consist of electronic donor (D) and acceptor (A) subunits connected via a methine bridge. They are highly polar organic π-conjugated molecules investigated for their self-assembly and optoelectronic properties. The accurate description of their structure–property relationships remains challenging. We report a comprehensive analysis modelling intra- and inter-molecular charge transport parameters for a library of merocyanines featuring different D/A combinations and lateral substituents. We found that constrained DFT correctly assesses the molecular and electronic structure in single crystals. The most effective charge transport pathways were identified and charge carrier mobilities were computed. We analyzed a large variety of single crystals highlighting the impact of alkyl substituents and casting conditions, drawing clear structure vs. charge transport relationships. Our modelling suggests that hole transport is maximized when dipolar molecules are packed in slipped not centrosymmetric pairs, arranged in 2D interconnected architectures. Computed and experimental charge mobilities for single crystals are in good agreement.

  @article{D1TC01511G, abstract = {Merocyanines consist of electronic donor (D) and acceptor (A) subunits connected via a methine bridge. They are highly polar organic π-conjugated molecules investigated for their self-assembly and optoelectronic properties. The accurate description of their structure–property relationships remains challenging. We report a comprehensive analysis modelling intra- and inter-molecular charge transport parameters for a library of merocyanines featuring different D/A combinations and lateral substituents. We found that constrained DFT correctly assesses the molecular and electronic structure in single crystals. The most effective charge transport pathways were identified and charge carrier mobilities were computed. We analyzed a large variety of single crystals highlighting the impact of alkyl substituents and casting conditions{,} drawing clear structure vs. charge transport relationships. Our modelling suggests that hole transport is maximized when dipolar molecules are packed in slipped not centrosymmetric pairs{,} arranged in 2D interconnected architectures. Computed and experimental charge mobilities for single crystals are in good agreement.}, author = {Gildemeister, Nora and Ricci, Gaetano and Böhner, Lukas and Neudörfl, Jörg M. and Hertel, Dirk and Würthner, Frank and Negri, Fabrizia and Meerholz, Klaus and Fazzi, Daniele}, journal = {J. Mater. Chem. C}, keywords = {myown}, number = 33, pages = {10851-10864}, publisher = {The Royal Society of Chemistry}, title = {Understanding the structural and charge transport property relationships for a variety of merocyanine single-crystals: a bottom up computational investigation}, volume = 9, year = 2021 }

  %0 Journal Article %1 D1TC01511G %A Gildemeister, Nora %A Ricci, Gaetano %A Böhner, Lukas %A Neudörfl, Jörg M. %A Hertel, Dirk %A Würthner, Frank %A Negri, Fabrizia %A Meerholz, Klaus %A Fazzi, Daniele %D 2021 %I The Royal Society of Chemistry %J J. Mater. Chem. C %N 33 %P 10851-10864 %R 10.1039/D1TC01511G %T Understanding the structural and charge transport property relationships for a variety of merocyanine single-crystals: a bottom up computational investigation %U http://dx.doi.org/10.1039/D1TC01511G %V 9 %X Merocyanines consist of electronic donor (D) and acceptor (A) subunits connected via a methine bridge. They are highly polar organic π-conjugated molecules investigated for their self-assembly and optoelectronic properties. The accurate description of their structure–property relationships remains challenging. We report a comprehensive analysis modelling intra- and inter-molecular charge transport parameters for a library of merocyanines featuring different D/A combinations and lateral substituents. We found that constrained DFT correctly assesses the molecular and electronic structure in single crystals. The most effective charge transport pathways were identified and charge carrier mobilities were computed. We analyzed a large variety of single crystals highlighting the impact of alkyl substituents and casting conditions, drawing clear structure vs. charge transport relationships. Our modelling suggests that hole transport is maximized when dipolar molecules are packed in slipped not centrosymmetric pairs, arranged in 2D interconnected architectures. Computed and experimental charge mobilities for single crystals are in good agreement.
• PAHs Containing both Heptagon and Pentagon: Corannulene Extension by [5+2] Annulation. Schnitzlein, Matthias; Mützel, Carina; Shoyama, Kazutaka; Farrell, Jeffrey M.; Würthner, Frank. In Eur. J. Org. Chem., 2022(5). 2021.
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  Utilizing Pd-catalyzed [5+2] annulation a series of heptagon-extended corannulenes could be synthesized from a borinic acid precursor furnished by C−H borylation strategy. Single-crystal X-ray analysis revealed the presence of two conformational enantiomers crystallizing in a racemic mixture. Through their embedded five- and seven-membered rings these polycyclic aromatic hydrocarbons (PAHs) exhibit both negative and positive curvature and UV/Vis/NIR absorption spectroscopy as well as cyclic voltammetry experiments provided insights into the influence of larger flanking aromatic systems and electron-donating substituents encompassing the heptagonal ring. Through [5+2] annulation of acenaphthylene an azulene-containing PAH with intriguing optoelectronical properties including a very small bandgap and absorption over the whole visible spectrum could be obtained. Theoretical calculations were employed to elucidate the long-wavelength absorption and aromaticity.

  @article{Schnitzlein_2021, abstract = {Utilizing Pd-catalyzed [5+2] annulation a series of heptagon-extended corannulenes could be synthesized from a borinic acid precursor furnished by C−H borylation strategy. Single-crystal X-ray analysis revealed the presence of two conformational enantiomers crystallizing in a racemic mixture. Through their embedded five- and seven-membered rings these polycyclic aromatic hydrocarbons (PAHs) exhibit both negative and positive curvature and UV/Vis/NIR absorption spectroscopy as well as cyclic voltammetry experiments provided insights into the influence of larger flanking aromatic systems and electron-donating substituents encompassing the heptagonal ring. Through [5+2] annulation of acenaphthylene an azulene-containing PAH with intriguing optoelectronical properties including a very small bandgap and absorption over the whole visible spectrum could be obtained. Theoretical calculations were employed to elucidate the long-wavelength absorption and aromaticity.}, author = {Schnitzlein, Matthias and Mützel, Carina and Shoyama, Kazutaka and Farrell, Jeffrey M. and Würthner, Frank}, journal = {Eur. J. Org. Chem.}, keywords = {myown}, month = 12, number = 5, publisher = {Wiley}, title = {PAHs Containing both Heptagon and Pentagon: Corannulene Extension by [5+2] Annulation}, volume = 2022, year = 2021 }

  %0 Journal Article %1 Schnitzlein_2021 %A Schnitzlein, Matthias %A Mützel, Carina %A Shoyama, Kazutaka %A Farrell, Jeffrey M. %A Würthner, Frank %D 2021 %I Wiley %J Eur. J. Org. Chem. %N 5 %R 10.1002/ejoc.202101273 %T PAHs Containing both Heptagon and Pentagon: Corannulene Extension by [5+2] Annulation %U https://doi.org/10.1002%2Fejoc.202101273 %V 2022 %X Utilizing Pd-catalyzed [5+2] annulation a series of heptagon-extended corannulenes could be synthesized from a borinic acid precursor furnished by C−H borylation strategy. Single-crystal X-ray analysis revealed the presence of two conformational enantiomers crystallizing in a racemic mixture. Through their embedded five- and seven-membered rings these polycyclic aromatic hydrocarbons (PAHs) exhibit both negative and positive curvature and UV/Vis/NIR absorption spectroscopy as well as cyclic voltammetry experiments provided insights into the influence of larger flanking aromatic systems and electron-donating substituents encompassing the heptagonal ring. Through [5+2] annulation of acenaphthylene an azulene-containing PAH with intriguing optoelectronical properties including a very small bandgap and absorption over the whole visible spectrum could be obtained. Theoretical calculations were employed to elucidate the long-wavelength absorption and aromaticity.
• Site-specific chemical doping reveals electron atmospheres at the surfaces of organic semiconductor crystals. He, Tao; Stolte, Matthias; Wang, Yan; Renner, Rebecca; Ruden, P. Paul; Würthner, Frank; Frisbie, C. Daniel. In Nature Materials, 20(11), pp. 1532–1538. 2021.
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  Chemical doping controls the electronic properties of organic semiconductors, but so far, doping protocols and mechanisms are less developed than in conventional semiconductors. Here we describe a unique, site-specific, n-type surface doping mecha- nism for single crystals of two benchmark organic semiconductors that produces dramatic improvement in electron transport and provides unprecedented evidence for doping-induced space charge. The surface doping chemistry specifically targets crys- tallographic step edges, which are known electron traps, simultaneously passivating the traps and releasing itinerant elec- trons. The effect on electron transport is profound: field-effect electron mobility increases by as much as a factor of ten, and its temperature-dependent behaviour switches from thermally activated to band-like. Our findings suggest new site-specific strategies to dope organic semiconductors that differ from the conventional redox chemistry of randomly distributed substi- tutional impurities. Critically, they also verify the presence of doping-induced electron atmospheres, confirming long-standing expectations for organic systems from conventional solid-state theory.

  @article{He_2021, abstract = {Chemical doping controls the electronic properties of organic semiconductors, but so far, doping protocols and mechanisms are less developed than in conventional semiconductors. Here we describe a unique, site-specific, n-type surface doping mecha- nism for single crystals of two benchmark organic semiconductors that produces dramatic improvement in electron transport and provides unprecedented evidence for doping-induced space charge. The surface doping chemistry specifically targets crys- tallographic step edges, which are known electron traps, simultaneously passivating the traps and releasing itinerant elec- trons. The effect on electron transport is profound: field-effect electron mobility increases by as much as a factor of ten, and its temperature-dependent behaviour switches from thermally activated to band-like. Our findings suggest new site-specific strategies to dope organic semiconductors that differ from the conventional redox chemistry of randomly distributed substi- tutional impurities. Critically, they also verify the presence of doping-induced electron atmospheres, confirming long-standing expectations for organic systems from conventional solid-state theory.}, author = {He, Tao and Stolte, Matthias and Wang, Yan and Renner, Rebecca and Ruden, P. Paul and Würthner, Frank and Frisbie, C. Daniel}, journal = {Nature Materials}, keywords = {myown}, month = {08}, number = 11, pages = {1532–1538}, publisher = {Springer Science and Business Media {LLC}}, title = {Site-specific chemical doping reveals electron atmospheres at the surfaces of organic semiconductor crystals}, volume = 20, year = 2021 }

  %0 Journal Article %1 He_2021 %A He, Tao %A Stolte, Matthias %A Wang, Yan %A Renner, Rebecca %A Ruden, P. Paul %A Würthner, Frank %A Frisbie, C. Daniel %D 2021 %I Springer Science and Business Media LLC %J Nature Materials %N 11 %P 1532--1538 %R 10.1038/s41563-021-01079-z %T Site-specific chemical doping reveals electron atmospheres at the surfaces of organic semiconductor crystals %U https://doi.org/10.1038%2Fs41563-021-01079-z %V 20 %X Chemical doping controls the electronic properties of organic semiconductors, but so far, doping protocols and mechanisms are less developed than in conventional semiconductors. Here we describe a unique, site-specific, n-type surface doping mecha- nism for single crystals of two benchmark organic semiconductors that produces dramatic improvement in electron transport and provides unprecedented evidence for doping-induced space charge. The surface doping chemistry specifically targets crys- tallographic step edges, which are known electron traps, simultaneously passivating the traps and releasing itinerant elec- trons. The effect on electron transport is profound: field-effect electron mobility increases by as much as a factor of ten, and its temperature-dependent behaviour switches from thermally activated to band-like. Our findings suggest new site-specific strategies to dope organic semiconductors that differ from the conventional redox chemistry of randomly distributed substi- tutional impurities. Critically, they also verify the presence of doping-induced electron atmospheres, confirming long-standing expectations for organic systems from conventional solid-state theory.
• Switching resonance character within merocyanine stacks and its impact on excited-state dynamics. Kim, Taeyeon; Kang, Seongsoo; Kirchner, Eva; Bialas, David; Kim, Woojae; Würthner, Frank; Kim, Dongho. In Chem, 7(3), pp. 715–725. 2021.
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  @article{Kim_2021, author = {Kim, Taeyeon and Kang, Seongsoo and Kirchner, Eva and Bialas, David and Kim, Woojae and Würthner, Frank and Kim, Dongho}, journal = {Chem}, keywords = {myown}, month = {03}, number = 3, pages = {715–725}, publisher = {Elsevier {BV}}, title = {Switching resonance character within merocyanine stacks and its impact on excited-state dynamics}, volume = 7, year = 2021 }

  %0 Journal Article %1 Kim_2021 %A Kim, Taeyeon %A Kang, Seongsoo %A Kirchner, Eva %A Bialas, David %A Kim, Woojae %A Würthner, Frank %A Kim, Dongho %D 2021 %I Elsevier BV %J Chem %N 3 %P 715--725 %R 10.1016/j.chempr.2020.12.003 %T Switching resonance character within merocyanine stacks and its impact on excited-state dynamics %U https://doi.org/10.1016%2Fj.chempr.2020.12.003 %V 7
• Perspectives in Dye Chemistry: A Rational Approach toward Functional Materials by Understanding the Aggregate State. Bialas, David; Kirchner, Eva; Röhr, Merle I. S.; Würthner, Frank. In J. Am. Chem. Soc., 143(12), pp. 4500–4518. 2021.
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  The past 20 years have witnessed a renaissance of dye chemistry, moving from traditional colorant research toward functional materials. Different from traditional colorant research, the properties of functional materials are governed extensively by intermolecular interactions, thereby entailing significant limitations to the classical approach based on molecular structure–molecular property (color, emission, redox properties, etc.) relationships for the respective dye molecules. However, as discussed in this Perspective, such an approach can be pursued for dye aggregates, and in many cases already well-tailored dimers are sufficient to understand the influence of supramolecular organization on the functional properties of ground and photoexcited states. Illustrative examples will be given for exciton coupling and charge-transfer coupling and how these properties relate to desirable functions such as fluorescence, symmetry-breaking charge separation, and singlet fission in molecular aggregates. While the progress in this research so far mostly originated from studies on well-defined folded and self-assembled structures composed of only two dye molecules, future work will have to advance toward larger oligomers of specific size and geometry. Furthermore, future experimental studies should be guided to a larger extent by theoretical predictions that may be supported by machine learning algorithms and new concepts from artificial intelligence. Beyond already pursued calculations of potential energy landscapes, we suggest the development of theoretical approaches that identify the most desirable dye aggregate structures for a particular property on functional energy landscapes.

  @article{Bialas_2021, abstract = {The past 20 years have witnessed a renaissance of dye chemistry, moving from traditional colorant research toward functional materials. Different from traditional colorant research, the properties of functional materials are governed extensively by intermolecular interactions, thereby entailing significant limitations to the classical approach based on molecular structure–molecular property (color, emission, redox properties, etc.) relationships for the respective dye molecules. However, as discussed in this Perspective, such an approach can be pursued for dye aggregates, and in many cases already well-tailored dimers are sufficient to understand the influence of supramolecular organization on the functional properties of ground and photoexcited states. Illustrative examples will be given for exciton coupling and charge-transfer coupling and how these properties relate to desirable functions such as fluorescence, symmetry-breaking charge separation, and singlet fission in molecular aggregates. While the progress in this research so far mostly originated from studies on well-defined folded and self-assembled structures composed of only two dye molecules, future work will have to advance toward larger oligomers of specific size and geometry. Furthermore, future experimental studies should be guided to a larger extent by theoretical predictions that may be supported by machine learning algorithms and new concepts from artificial intelligence. Beyond already pursued calculations of potential energy landscapes, we suggest the development of theoretical approaches that identify the most desirable dye aggregate structures for a particular property on functional energy landscapes.}, author = {Bialas, David and Kirchner, Eva and Röhr, Merle I. S. and Würthner, Frank}, journal = {J. Am. Chem. Soc.}, keywords = {myown}, month = {03}, number = 12, pages = {4500–4518}, publisher = {American Chemical Society ({ACS})}, title = {Perspectives in Dye Chemistry: A Rational Approach toward Functional Materials by Understanding the Aggregate State}, volume = 143, year = 2021 }

  %0 Journal Article %1 Bialas_2021 %A Bialas, David %A Kirchner, Eva %A Röhr, Merle I. S. %A Würthner, Frank %D 2021 %I American Chemical Society (ACS) %J J. Am. Chem. Soc. %N 12 %P 4500--4518 %R 10.1021/jacs.0c13245 %T Perspectives in Dye Chemistry: A Rational Approach toward Functional Materials by Understanding the Aggregate State %U https://doi.org/10.1021%2Fjacs.0c13245 %V 143 %X The past 20 years have witnessed a renaissance of dye chemistry, moving from traditional colorant research toward functional materials. Different from traditional colorant research, the properties of functional materials are governed extensively by intermolecular interactions, thereby entailing significant limitations to the classical approach based on molecular structure–molecular property (color, emission, redox properties, etc.) relationships for the respective dye molecules. However, as discussed in this Perspective, such an approach can be pursued for dye aggregates, and in many cases already well-tailored dimers are sufficient to understand the influence of supramolecular organization on the functional properties of ground and photoexcited states. Illustrative examples will be given for exciton coupling and charge-transfer coupling and how these properties relate to desirable functions such as fluorescence, symmetry-breaking charge separation, and singlet fission in molecular aggregates. While the progress in this research so far mostly originated from studies on well-defined folded and self-assembled structures composed of only two dye molecules, future work will have to advance toward larger oligomers of specific size and geometry. Furthermore, future experimental studies should be guided to a larger extent by theoretical predictions that may be supported by machine learning algorithms and new concepts from artificial intelligence. Beyond already pursued calculations of potential energy landscapes, we suggest the development of theoretical approaches that identify the most desirable dye aggregate structures for a particular property on functional energy landscapes.
• Tuning phenoxyl-substituted diketopyrrolopyrroles from quinoidal to biradical ground states through (hetero-)aromatic linkers. Rausch, Rodger; Röhr, Merle I. S.; Schmidt, David; Krummenacher, Ivo; Braunschweig, Holger; Würthner, Frank. In Chem. Sci., 12(2), pp. 793–802. 2021.
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  Strongly fluorescent halochromic 2,6-di-tert-butyl-phenol-functionalised phenyl-, thienyl- and furyl-substituted diketopyrrolopyrrole (DPP) dyes were deprotonated and oxidised to give either phenylene-linked DPP1˙˙ biradical (y0 = 0.75) with a singlet open shell ground state and a thermally populated triplet state (ΔEST = 19 meV; 1.8 kJ mol−1; 0.43 kcal mol−1) or thienylene/furylene-linked DPP2q and DPP3q compounds with closed shell quinoidal ground states. Accordingly, we identified the aromaticity of the conjugated (hetero-)aromatic bridge to be key for modulating the electronic character of these biradicaloid compounds and achieved a spin crossover from closed shell quinones DPP2q and DPP3q to open shell biradical DPP1˙˙ as confirmed by optical and magnetic spectroscopic studies (UV/vis/NIR, NMR, EPR) as well as computational investigations (spin-flip TD-DFT calculations in combination with CASSCF(4,4) and harmonic oscillator model of aromaticity (HOMA) analysis). Spectroelectrochemical studies and comproportionation experiments further prove the reversible formation of mixed-valent radical anions for the DPP2q and DPP3q quinoidal compounds with absorption bands edging into the NIR spectral region.

  @article{D0SC05475E, abstract = {Strongly fluorescent halochromic 2{,}6-di-tert-butyl-phenol-functionalised phenyl-{,} thienyl- and furyl-substituted diketopyrrolopyrrole (DPP) dyes were deprotonated and oxidised to give either phenylene-linked DPP1˙˙ biradical (y0 = 0.75) with a singlet open shell ground state and a thermally populated triplet state (ΔEST = 19 meV; 1.8 kJ mol−1; 0.43 kcal mol−1) or thienylene/furylene-linked DPP2q and DPP3q compounds with closed shell quinoidal ground states. Accordingly{,} we identified the aromaticity of the conjugated (hetero-)aromatic bridge to be key for modulating the electronic character of these biradicaloid compounds and achieved a spin crossover from closed shell quinones DPP2q and DPP3q to open shell biradical DPP1˙˙ as confirmed by optical and magnetic spectroscopic studies (UV/vis/NIR{,} NMR{,} EPR) as well as computational investigations (spin-flip TD-DFT calculations in combination with CASSCF(4{,}4) and harmonic oscillator model of aromaticity (HOMA) analysis). Spectroelectrochemical studies and comproportionation experiments further prove the reversible formation of mixed-valent radical anions for the DPP2q and DPP3q quinoidal compounds with absorption bands edging into the NIR spectral region.}, author = {Rausch, Rodger and Röhr, Merle I. S. and Schmidt, David and Krummenacher, Ivo and Braunschweig, Holger and Würthner, Frank}, journal = {Chem. Sci.}, keywords = {myown}, number = 2, pages = {793-802}, publisher = {The Royal Society of Chemistry}, title = {Tuning phenoxyl-substituted diketopyrrolopyrroles from quinoidal to biradical ground states through (hetero-)aromatic linkers}, volume = 12, year = 2021 }

  %0 Journal Article %1 D0SC05475E %A Rausch, Rodger %A Röhr, Merle I. S. %A Schmidt, David %A Krummenacher, Ivo %A Braunschweig, Holger %A Würthner, Frank %D 2021 %I The Royal Society of Chemistry %J Chem. Sci. %N 2 %P 793-802 %R 10.1039/D0SC05475E %T Tuning phenoxyl-substituted diketopyrrolopyrroles from quinoidal to biradical ground states through (hetero-)aromatic linkers %U http://dx.doi.org/10.1039/D0SC05475E %V 12 %X Strongly fluorescent halochromic 2,6-di-tert-butyl-phenol-functionalised phenyl-, thienyl- and furyl-substituted diketopyrrolopyrrole (DPP) dyes were deprotonated and oxidised to give either phenylene-linked DPP1˙˙ biradical (y0 = 0.75) with a singlet open shell ground state and a thermally populated triplet state (ΔEST = 19 meV; 1.8 kJ mol−1; 0.43 kcal mol−1) or thienylene/furylene-linked DPP2q and DPP3q compounds with closed shell quinoidal ground states. Accordingly, we identified the aromaticity of the conjugated (hetero-)aromatic bridge to be key for modulating the electronic character of these biradicaloid compounds and achieved a spin crossover from closed shell quinones DPP2q and DPP3q to open shell biradical DPP1˙˙ as confirmed by optical and magnetic spectroscopic studies (UV/vis/NIR, NMR, EPR) as well as computational investigations (spin-flip TD-DFT calculations in combination with CASSCF(4,4) and harmonic oscillator model of aromaticity (HOMA) analysis). Spectroelectrochemical studies and comproportionation experiments further prove the reversible formation of mixed-valent radical anions for the DPP2q and DPP3q quinoidal compounds with absorption bands edging into the NIR spectral region.
• Solvent Effects in Supramolecular Chemistry: Linear Free Energy Relationships for Common Intermolecular Interactions. Würthner, Frank. In J. Org. Chem, 87(3), pp. 1602–1615. 2021.
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  The proper choice of solvent is of major importance for all studies in supramolecular chemistry, including molecular recognition in host−guest systems, intramolecular folding, self-assembly, and supramolecular polymerization. In this Perspective, the usefulness of linear free energy relationships (LFERs) is highlighted to unravel the effect of solvents on coordinate bonding (e.g., cation- crown ether), hydrogen bonding, halogen bonding, dipolar aggregation, and π−π- stacking. For all of these intermolecular interactions widely applied in supramolecular systems, LFER relationships between the Gibbs binding energies and common solvent polarity scales including ET(30), π*, α or β based on solvatochromic dyes, scales derived from binding processes such as Gutmann donor and acceptor numbers or hydrogen bond donor and acceptor scales, or physical functions like the Kirkwood−Onsager or the Liptay−Onsager functions could be demonstrated. These relationships can now be applied toward a better understanding of the prevailing intermolecular forces for supramolecular interactions. They further enable a rational selection of the most suitable solvent for the preparation of self-assembled materials and the estimation of binding constants without the need for time-consuming comprehensive investigations of solvents.

  @article{W_rthner_2021, abstract = {The proper choice of solvent is of major importance for all studies in supramolecular chemistry, including molecular recognition in host−guest systems, intramolecular folding, self-assembly, and supramolecular polymerization. In this Perspective, the usefulness of linear free energy relationships (LFERs) is highlighted to unravel the effect of solvents on coordinate bonding (e.g., cation- crown ether), hydrogen bonding, halogen bonding, dipolar aggregation, and π−π- stacking. For all of these intermolecular interactions widely applied in supramolecular systems, LFER relationships between the Gibbs binding energies and common solvent polarity scales including ET(30), π*, α or β based on solvatochromic dyes, scales derived from binding processes such as Gutmann donor and acceptor numbers or hydrogen bond donor and acceptor scales, or physical functions like the Kirkwood−Onsager or the Liptay−Onsager functions could be demonstrated. These relationships can now be applied toward a better understanding of the prevailing intermolecular forces for supramolecular interactions. They further enable a rational selection of the most suitable solvent for the preparation of self-assembled materials and the estimation of binding constants without the need for time-consuming comprehensive investigations of solvents.}, author = {Würthner, Frank}, journal = {J. Org. Chem}, keywords = {myown}, month = {05}, number = 3, pages = {1602–1615}, publisher = {American Chemical Society ({ACS})}, title = {Solvent Effects in Supramolecular Chemistry: Linear Free Energy Relationships for Common Intermolecular Interactions}, volume = 87, year = 2021 }

  %0 Journal Article %1 W_rthner_2021 %A Würthner, Frank %D 2021 %I American Chemical Society (ACS) %J J. Org. Chem %N 3 %P 1602--1615 %R 10.1021/acs.joc.1c00625 %T Solvent Effects in Supramolecular Chemistry: Linear Free Energy Relationships for Common Intermolecular Interactions %U https://doi.org/10.1021%2Facs.joc.1c00625 %V 87 %X The proper choice of solvent is of major importance for all studies in supramolecular chemistry, including molecular recognition in host−guest systems, intramolecular folding, self-assembly, and supramolecular polymerization. In this Perspective, the usefulness of linear free energy relationships (LFERs) is highlighted to unravel the effect of solvents on coordinate bonding (e.g., cation- crown ether), hydrogen bonding, halogen bonding, dipolar aggregation, and π−π- stacking. For all of these intermolecular interactions widely applied in supramolecular systems, LFER relationships between the Gibbs binding energies and common solvent polarity scales including ET(30), π*, α or β based on solvatochromic dyes, scales derived from binding processes such as Gutmann donor and acceptor numbers or hydrogen bond donor and acceptor scales, or physical functions like the Kirkwood−Onsager or the Liptay−Onsager functions could be demonstrated. These relationships can now be applied toward a better understanding of the prevailing intermolecular forces for supramolecular interactions. They further enable a rational selection of the most suitable solvent for the preparation of self-assembled materials and the estimation of binding constants without the need for time-consuming comprehensive investigations of solvents.
• Deracemization of Carbohelicenes by a Chiral Perylene Bisimide Cyclophane Template Catalyst. Weh, Manuel; Rühe, Jessica; Herbert, Benedikt; Krause, Ana-Maria; Würthner, Frank. In Angew. Chem. Int. Ed., 60(28), pp. 15323–15327. 2021.
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  Deracemization describes the conversion of a racemic mixture of a chiral molecule into an enantioenriched mixture or an enantiopure compound without structural modifications. Herein, we report an inherently chiral perylene bisimide (PBI) cyclophane whose chiral pocket is capable of transforming a racemic mixture of [5]-helicene into an enantioenriched mixture with an enantiomeric excess of 66 %. UV/Vis and fluorescence titration studies reveal this cyclophane host composed of two helically twisted PBI dyes has high binding affinities for the respective homochiral carbohelicene guests, with outstanding binding constants of up to 3.9×1010 m−1 for [4]-helicene. 2D NMR studies and single-crystal X-ray analysis demonstrate that the observed strong and enantioselective binding of homochiral carbohelicenes and the successful template-catalyzed deracemization of [5]-helicene can be explained by the enzyme-like perfect shape complementarity of the macrocyclic supramolecular host.

  @article{Weh_2021, abstract = {Deracemization describes the conversion of a racemic mixture of a chiral molecule into an enantioenriched mixture or an enantiopure compound without structural modifications. Herein, we report an inherently chiral perylene bisimide (PBI) cyclophane whose chiral pocket is capable of transforming a racemic mixture of [5]-helicene into an enantioenriched mixture with an enantiomeric excess of 66 %. UV/Vis and fluorescence titration studies reveal this cyclophane host composed of two helically twisted PBI dyes has high binding affinities for the respective homochiral carbohelicene guests, with outstanding binding constants of up to 3.9×1010 m−1 for [4]-helicene. 2D NMR studies and single-crystal X-ray analysis demonstrate that the observed strong and enantioselective binding of homochiral carbohelicenes and the successful template-catalyzed deracemization of [5]-helicene can be explained by the enzyme-like perfect shape complementarity of the macrocyclic supramolecular host.}, author = {Weh, Manuel and Rühe, Jessica and Herbert, Benedikt and Krause, Ana-Maria and Würthner, Frank}, journal = {Angew. Chem. Int. Ed.}, keywords = {myown}, month = {06}, number = 28, pages = {15323–15327}, publisher = {Wiley}, title = {Deracemization of Carbohelicenes by a Chiral Perylene Bisimide Cyclophane Template Catalyst}, volume = 60, year = 2021 }

  %0 Journal Article %1 Weh_2021 %A Weh, Manuel %A Rühe, Jessica %A Herbert, Benedikt %A Krause, Ana-Maria %A Würthner, Frank %D 2021 %I Wiley %J Angew. Chem. Int. Ed. %N 28 %P 15323--15327 %R 10.1002/anie.202104591 %T Deracemization of Carbohelicenes by a Chiral Perylene Bisimide Cyclophane Template Catalyst %U https://doi.org/10.1002%2Fanie.202104591 %V 60 %X Deracemization describes the conversion of a racemic mixture of a chiral molecule into an enantioenriched mixture or an enantiopure compound without structural modifications. Herein, we report an inherently chiral perylene bisimide (PBI) cyclophane whose chiral pocket is capable of transforming a racemic mixture of [5]-helicene into an enantioenriched mixture with an enantiomeric excess of 66 %. UV/Vis and fluorescence titration studies reveal this cyclophane host composed of two helically twisted PBI dyes has high binding affinities for the respective homochiral carbohelicene guests, with outstanding binding constants of up to 3.9×1010 m−1 for [4]-helicene. 2D NMR studies and single-crystal X-ray analysis demonstrate that the observed strong and enantioselective binding of homochiral carbohelicenes and the successful template-catalyzed deracemization of [5]-helicene can be explained by the enzyme-like perfect shape complementarity of the macrocyclic supramolecular host.
• Two-step anti-cooperative self-assembly process into defined π-stacked dye oligomers: insights into aggregation-induced enhanced emission. Vonhausen, Yvonne; Lohr, Andreas; Stolte, Matthias; Würthner, Frank. In Chem. Sci., 12(37), pp. 12302–12314. 2021.
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  Aggregation-induced emission enhancement (AIEE) phenomena received great popularity during the last decade but in most cases insights into the packing structure – fluorescence properties remained scarce. Here, an almost non-fluorescent merocyanine dye was equipped with large solubilizing substituents, which allowed the investigation of it's aggregation behaviour in unpolar solvents over a large concentration range (10−2 to 10−7 M). In depth analysis of the self-assembly process by concentration-dependent UV/Vis spectroscopy at different temperatures revealed a two-step anti-cooperative aggregation mechanism. In the first step a co-facially stacked dimer is formed driven by dipole–dipole interactions. In a second step these dimers self-assemble to give an oligomer stack consisting of about ten dyes. Concentration- and temperature-dependent UV/Vis spectroscopy provided insight into the thermodynamic parameters and allowed to identify conditions where either the monomer, the dimer or the decamer prevails. The centrosymmetric dimer structure could be proven by 2D NMR spectroscopy. For the larger decamer atomic force microscopy (AFM), diffusion ordered spectroscopy (DOSY) and vapour pressure osmometric (VPO) measurements consistently indicated that it is of small and defined size. Fluorescence, circular dichroism (CD) and circularly polarized luminescence (CPL) spectroscopy provided insights into the photofunctional properties of the dye aggregates. Starting from an essentially non-fluorescent monomer (ΦFl = 0.23%) a strong AIEE effect with excimer-type fluorescence (large Stokes shift, increased fluorescence lifetime) is observed upon formation of the dimer (ΦFl = 2.3%) and decamer (ΦFl = 4.5%) stack. This increase in fluorescence is accompanied for both aggregates by an aggregation-induced CPL enhancement with a strong increase of the glum from ∼0.001 for the dimer up to ∼0.011 for the higher aggregate. Analysis of the radiative and non-radiative decay rates corroborates the interpretation that the AIEE effect originates from a pronounced decrease of the non-radiative rate due to π–π-stacking induced rigidification that outmatches the effect of the reduced radiative rate that originates from the H-type exciton coupling in the co-facially stacked dyes.

  @article{D1SC03813C, abstract = {Aggregation-induced emission enhancement (AIEE) phenomena received great popularity during the last decade but in most cases insights into the packing structure – fluorescence properties remained scarce. Here{,} an almost non-fluorescent merocyanine dye was equipped with large solubilizing substituents{,} which allowed the investigation of it{'}s aggregation behaviour in unpolar solvents over a large concentration range (10−2 to 10−7 M). In depth analysis of the self-assembly process by concentration-dependent UV/Vis spectroscopy at different temperatures revealed a two-step anti-cooperative aggregation mechanism. In the first step a co-facially stacked dimer is formed driven by dipole–dipole interactions. In a second step these dimers self-assemble to give an oligomer stack consisting of about ten dyes. Concentration- and temperature-dependent UV/Vis spectroscopy provided insight into the thermodynamic parameters and allowed to identify conditions where either the monomer{,} the dimer or the decamer prevails. The centrosymmetric dimer structure could be proven by 2D NMR spectroscopy. For the larger decamer atomic force microscopy (AFM){,} diffusion ordered spectroscopy (DOSY) and vapour pressure osmometric (VPO) measurements consistently indicated that it is of small and defined size. Fluorescence{,} circular dichroism (CD) and circularly polarized luminescence (CPL) spectroscopy provided insights into the photofunctional properties of the dye aggregates. Starting from an essentially non-fluorescent monomer (ΦFl = 0.23%) a strong AIEE effect with excimer-type fluorescence (large Stokes shift{,} increased fluorescence lifetime) is observed upon formation of the dimer (ΦFl = 2.3%) and decamer (ΦFl = 4.5%) stack. This increase in fluorescence is accompanied for both aggregates by an aggregation-induced CPL enhancement with a strong increase of the glum from ∼0.001 for the dimer up to ∼0.011 for the higher aggregate. Analysis of the radiative and non-radiative decay rates corroborates the interpretation that the AIEE effect originates from a pronounced decrease of the non-radiative rate due to π–π-stacking induced rigidification that outmatches the effect of the reduced radiative rate that originates from the H-type exciton coupling in the co-facially stacked dyes.}, author = {Vonhausen, Yvonne and Lohr, Andreas and Stolte, Matthias and Würthner, Frank}, journal = {Chem. Sci.}, keywords = {myown}, number = 37, pages = {12302-12314}, publisher = {The Royal Society of Chemistry}, title = {Two-step anti-cooperative self-assembly process into defined π-stacked dye oligomers: insights into aggregation-induced enhanced emission}, volume = 12, year = 2021 }

  %0 Journal Article %1 D1SC03813C %A Vonhausen, Yvonne %A Lohr, Andreas %A Stolte, Matthias %A Würthner, Frank %D 2021 %I The Royal Society of Chemistry %J Chem. Sci. %N 37 %P 12302-12314 %R 10.1039/D1SC03813C %T Two-step anti-cooperative self-assembly process into defined π-stacked dye oligomers: insights into aggregation-induced enhanced emission %U http://dx.doi.org/10.1039/D1SC03813C %V 12 %X Aggregation-induced emission enhancement (AIEE) phenomena received great popularity during the last decade but in most cases insights into the packing structure – fluorescence properties remained scarce. Here, an almost non-fluorescent merocyanine dye was equipped with large solubilizing substituents, which allowed the investigation of it's aggregation behaviour in unpolar solvents over a large concentration range (10−2 to 10−7 M). In depth analysis of the self-assembly process by concentration-dependent UV/Vis spectroscopy at different temperatures revealed a two-step anti-cooperative aggregation mechanism. In the first step a co-facially stacked dimer is formed driven by dipole–dipole interactions. In a second step these dimers self-assemble to give an oligomer stack consisting of about ten dyes. Concentration- and temperature-dependent UV/Vis spectroscopy provided insight into the thermodynamic parameters and allowed to identify conditions where either the monomer, the dimer or the decamer prevails. The centrosymmetric dimer structure could be proven by 2D NMR spectroscopy. For the larger decamer atomic force microscopy (AFM), diffusion ordered spectroscopy (DOSY) and vapour pressure osmometric (VPO) measurements consistently indicated that it is of small and defined size. Fluorescence, circular dichroism (CD) and circularly polarized luminescence (CPL) spectroscopy provided insights into the photofunctional properties of the dye aggregates. Starting from an essentially non-fluorescent monomer (ΦFl = 0.23%) a strong AIEE effect with excimer-type fluorescence (large Stokes shift, increased fluorescence lifetime) is observed upon formation of the dimer (ΦFl = 2.3%) and decamer (ΦFl = 4.5%) stack. This increase in fluorescence is accompanied for both aggregates by an aggregation-induced CPL enhancement with a strong increase of the glum from ∼0.001 for the dimer up to ∼0.011 for the higher aggregate. Analysis of the radiative and non-radiative decay rates corroborates the interpretation that the AIEE effect originates from a pronounced decrease of the non-radiative rate due to π–π-stacking induced rigidification that outmatches the effect of the reduced radiative rate that originates from the H-type exciton coupling in the co-facially stacked dyes.
• Reversible fluorescence modulation through the photoisomerization of an azobenzene-bridged perylene bisimide cyclophane. Ouyang, Guanghui; Bialas, David; Würthner, Frank. In Org. Chem. Front., 8(7), pp. 1424–1430. 2021.
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  A new type of perylene bisimide (PBI) cyclophane in which two PBI chromophores were linked via an azobenzene (Azo) bridge was designed and synthesized. It was found that the integration of electron-donating azobenzene and electron-deficient PBI in a well-defined cyclophane enables the regulation of the fluorescence lifetime and quantum yield of the PBI units. With the aid of a high efficiency trans → cis transformation of the azobenzene moiety, the PBI–PBI chromophore distance can be effectively controlled as revealed by exciton coupling and density functional theory (DFT) computation, leading to additional non-radiative decay pathways and a pronounced fluorescence quenching due to cooperative adjustments of PBI–PBI and PBI–Azo interactions. Reversible fluorescence intensity switching for at least five cycles was successfully achieved with alternate UV and visible light irradiation. These well-controlled fluorescence modulation and photoswitching behaviours not only provide insights into interchromophoric interactions but also contribute to the development of stimuli-responsive luminescent macrocycles.

  @article{D0QO01635G, abstract = {A new type of perylene bisimide (PBI) cyclophane in which two PBI chromophores were linked via an azobenzene (Azo) bridge was designed and synthesized. It was found that the integration of electron-donating azobenzene and electron-deficient PBI in a well-defined cyclophane enables the regulation of the fluorescence lifetime and quantum yield of the PBI units. With the aid of a high efficiency trans → cis transformation of the azobenzene moiety{,} the PBI–PBI chromophore distance can be effectively controlled as revealed by exciton coupling and density functional theory (DFT) computation{,} leading to additional non-radiative decay pathways and a pronounced fluorescence quenching due to cooperative adjustments of PBI–PBI and PBI–Azo interactions. Reversible fluorescence intensity switching for at least five cycles was successfully achieved with alternate UV and visible light irradiation. These well-controlled fluorescence modulation and photoswitching behaviours not only provide insights into interchromophoric interactions but also contribute to the development of stimuli-responsive luminescent macrocycles.}, author = {Ouyang, Guanghui and Bialas, David and Würthner, Frank}, journal = {Org. Chem. Front.}, keywords = {myown}, number = 7, pages = {1424-1430}, publisher = {The Royal Society of Chemistry}, title = {Reversible fluorescence modulation through the photoisomerization of an azobenzene-bridged perylene bisimide cyclophane}, volume = 8, year = 2021 }

  %0 Journal Article %1 D0QO01635G %A Ouyang, Guanghui %A Bialas, David %A Würthner, Frank %D 2021 %I The Royal Society of Chemistry %J Org. Chem. Front. %N 7 %P 1424-1430 %R 10.1039/D0QO01635G %T Reversible fluorescence modulation through the photoisomerization of an azobenzene-bridged perylene bisimide cyclophane %U http://dx.doi.org/10.1039/D0QO01635G %V 8 %X A new type of perylene bisimide (PBI) cyclophane in which two PBI chromophores were linked via an azobenzene (Azo) bridge was designed and synthesized. It was found that the integration of electron-donating azobenzene and electron-deficient PBI in a well-defined cyclophane enables the regulation of the fluorescence lifetime and quantum yield of the PBI units. With the aid of a high efficiency trans → cis transformation of the azobenzene moiety, the PBI–PBI chromophore distance can be effectively controlled as revealed by exciton coupling and density functional theory (DFT) computation, leading to additional non-radiative decay pathways and a pronounced fluorescence quenching due to cooperative adjustments of PBI–PBI and PBI–Azo interactions. Reversible fluorescence intensity switching for at least five cycles was successfully achieved with alternate UV and visible light irradiation. These well-controlled fluorescence modulation and photoswitching behaviours not only provide insights into interchromophoric interactions but also contribute to the development of stimuli-responsive luminescent macrocycles.
• Double J-Coupling Strategy for Near Infrared Emitters. Shen, Chia-An; Stolte, Matthias; Kim, Jin Hong; Rausch, Anja; Würthner, Frank. In J. Am. Chem. Soc., 143(31), pp. 11946–11950. 2021.
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  Fluorophores emitting in the near-infrared (NIR) are highly desired for various applications, but increasing nonradiative rates cause severe fluorescence quenching for wavelengths beyond 800 nm. Here, a bis(squaraine) dye is reported that bears two NIR dyes in a head-to-tail chromophore arrangement. This arrangement leads to intramolecular J-type exciton coupling, resulting in an absorption maximum at 961 nm and a fluorescence peak at 971 nm with a quantum yield of 0.33% in chloroform. In less polar toluene, the bis(squaraine) self-assembles into nanofibers, affording another bathochromic shift with an absorption maximum at 1095 nm and a fluorescence peak at 1116 nm originating from intermolecular J-type coupling.

  @article{Shen_2021, abstract = {Fluorophores emitting in the near-infrared (NIR) are highly desired for various applications, but increasing nonradiative rates cause severe fluorescence quenching for wavelengths beyond 800 nm. Here, a bis(squaraine) dye is reported that bears two NIR dyes in a head-to-tail chromophore arrangement. This arrangement leads to intramolecular J-type exciton coupling, resulting in an absorption maximum at 961 nm and a fluorescence peak at 971 nm with a quantum yield of 0.33% in chloroform. In less polar toluene, the bis(squaraine) self-assembles into nanofibers, affording another bathochromic shift with an absorption maximum at 1095 nm and a fluorescence peak at 1116 nm originating from intermolecular J-type coupling.}, author = {Shen, Chia-An and Stolte, Matthias and Kim, Jin Hong and Rausch, Anja and Würthner, Frank}, journal = {J. Am. Chem. Soc.}, keywords = {myown}, month = {07}, number = 31, pages = {11946–11950}, publisher = {American Chemical Society ({ACS})}, title = {Double J-Coupling Strategy for Near Infrared Emitters}, volume = 143, year = 2021 }

  %0 Journal Article %1 Shen_2021 %A Shen, Chia-An %A Stolte, Matthias %A Kim, Jin Hong %A Rausch, Anja %A Würthner, Frank %D 2021 %I American Chemical Society (ACS) %J J. Am. Chem. Soc. %N 31 %P 11946--11950 %R 10.1021/jacs.1c05934 %T Double J-Coupling Strategy for Near Infrared Emitters %U https://doi.org/10.1021%2Fjacs.1c05934 %V 143 %X Fluorophores emitting in the near-infrared (NIR) are highly desired for various applications, but increasing nonradiative rates cause severe fluorescence quenching for wavelengths beyond 800 nm. Here, a bis(squaraine) dye is reported that bears two NIR dyes in a head-to-tail chromophore arrangement. This arrangement leads to intramolecular J-type exciton coupling, resulting in an absorption maximum at 961 nm and a fluorescence peak at 971 nm with a quantum yield of 0.33% in chloroform. In less polar toluene, the bis(squaraine) self-assembles into nanofibers, affording another bathochromic shift with an absorption maximum at 1095 nm and a fluorescence peak at 1116 nm originating from intermolecular J-type coupling.
• Merocyanine Dyes with Extended Polymethine Chains by Simple Two-Step Condensation Sequence. Arjona-Esteban, Alhama; Rausch, Anja; Vysotsky, Myroslav O.; Würthner, Frank. In Synthesis, 53(02), pp. 318–325. 2021.
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  We describe a synthetic method for the synthesis of merocyanine dyes containing a bridge with three conjugated double bonds. This method consists of two successive condensation reactions. The first one is made between CH-acidic indane-1,3-dione acceptor units and an appropriate ketone (here acetone or hexan-2-one). The extended acceptor thus obtained is condensed with an aldehyde in the next step. The dyes show high tinctorial strength due to intense absorption bands at wavelengths between 500 and 750 nm.

  @article{arjonaesteban2021merocyanine, abstract = {We describe a synthetic method for the synthesis of merocyanine dyes containing a bridge with three conjugated double bonds. This method consists of two successive condensation reactions. The first one is made between CH-acidic indane-1,3-dione acceptor units and an appropriate ketone (here acetone or hexan-2-one). The extended acceptor thus obtained is condensed with an aldehyde in the next step. The dyes show high tinctorial strength due to intense absorption bands at wavelengths between 500 and 750 nm.}, author = {Arjona-Esteban, Alhama and Rausch, Anja and Vysotsky, Myroslav O. and Würthner, Frank}, journal = {Synthesis}, keywords = {myown}, number = {02}, pages = {318-325–}, title = {Merocyanine Dyes with Extended Polymethine Chains by Simple Two-Step Condensation Sequence}, volume = 53, year = 2021 }

  %0 Journal Article %1 arjonaesteban2021merocyanine %A Arjona-Esteban, Alhama %A Rausch, Anja %A Vysotsky, Myroslav O. %A Würthner, Frank %D 2021 %J Synthesis %N 02 %P 318-325-- %T Merocyanine Dyes with Extended Polymethine Chains by Simple Two-Step Condensation Sequence %V 53 %X We describe a synthetic method for the synthesis of merocyanine dyes containing a bridge with three conjugated double bonds. This method consists of two successive condensation reactions. The first one is made between CH-acidic indane-1,3-dione acceptor units and an appropriate ketone (here acetone or hexan-2-one). The extended acceptor thus obtained is condensed with an aldehyde in the next step. The dyes show high tinctorial strength due to intense absorption bands at wavelengths between 500 and 750 nm.

• On the photophysical properties of IrIII, PtII, and PdII (phenylpyrazole) (phenyldipyrrin) complexes. Föller, Jelena; Friese, Daniel H.; Riese, Stefan; Kaminski, Jeremy M.; Metz, Simon; Schmidt, David; Würthner, Frank; Lambert, Christoph; Marian, Christel M. In Phys. Chem. Chem. Phys., 22(6), pp. 3217–3233. 2020.
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  The absorption and emission characteristics of (ppz)2(dipy)IrIII, (ppz)(dipy)PtII and (ppz)(dipy)PdII, where ppz stands for phenylpyrazole and dipy for a phenyl meso-substituted dipyrrin ligand, have been investigated by means of combined density functional theory and multireference configuration interaction including scalar relativistic and spin–orbit coupling effects. These results were compared with experimental spectra. The complexes exhibit a high density of low-lying electronically excited states originating from ligand-centered (LC) and metal-to-ligand charge transfer (MLCT) states involving the dipyrrin ligand. In addition, metal-centered (MC) states are found to be low-lying in the Pd complex. In all three cases, the first strong absorption band and the phosphorescence emission band stem from LC excitations on the dipyrrin ligand with small MLCT contributions. The MLCT states show more pronounced relaxation effects than the LC states, with the consequence that the first excited state with predominant singlet multiplicity is of SMLCT/LC type in the heavier Ir and Pt complexes. Substantial spin–orbit coupling between SMLCT/LC and TLC enables fast and efficient intersystem crossing (ISC) and a high triplet quantum yield. Phosphorescence rate constants are rather small in accord with the dominant LC character of the transitions. Out-of-plane distortion promotes nonradiative decay of the excited state population via the MC states thus explaining the lower phosphorescence quantum yield of the Pt complex. The spectral properties of the Pd complex are different in many aspects. Optimization of the S1 state yields a dipyrrin intraligand charge transfer (ILCT) state with highly distorted nuclear arrangement in the butterfly conformers leading to nonradiative deactivation. In contrast, the primarily excited SLC state and the SMLCT/LC state of the twist conformer have nearly equal adiabatic excitation energies. The lack of a driving force toward the SMLCT/LC minimum, the high fluorescence rate constant of the bright SLC state and its moderately efficient ISC to the triplet manifold explain the experimentally observed dual emission of the Pd complex at room temperature.

  @article{C9CP05603C, abstract = {The absorption and emission characteristics of (ppz)2(dipy)IrIII, (ppz)(dipy)PtII and (ppz)(dipy)PdII, where ppz stands for phenylpyrazole and dipy for a phenyl meso-substituted dipyrrin ligand, have been investigated by means of combined density functional theory and multireference configuration interaction including scalar relativistic and spin–orbit coupling effects. These results were compared with experimental spectra. The complexes exhibit a high density of low-lying electronically excited states originating from ligand-centered (LC) and metal-to-ligand charge transfer (MLCT) states involving the dipyrrin ligand. In addition, metal-centered (MC) states are found to be low-lying in the Pd complex. In all three cases, the first strong absorption band and the phosphorescence emission band stem from LC excitations on the dipyrrin ligand with small MLCT contributions. The MLCT states show more pronounced relaxation effects than the LC states, with the consequence that the first excited state with predominant singlet multiplicity is of SMLCT/LC type in the heavier Ir and Pt complexes. Substantial spin–orbit coupling between SMLCT/LC and TLC enables fast and efficient intersystem crossing (ISC) and a high triplet quantum yield. Phosphorescence rate constants are rather small in accord with the dominant LC character of the transitions. Out-of-plane distortion promotes nonradiative decay of the excited state population via the MC states thus explaining the lower phosphorescence quantum yield of the Pt complex. The spectral properties of the Pd complex are different in many aspects. Optimization of the S1 state yields a dipyrrin intraligand charge transfer (ILCT) state with highly distorted nuclear arrangement in the butterfly conformers leading to nonradiative deactivation. In contrast, the primarily excited SLC state and the SMLCT/LC state of the twist conformer have nearly equal adiabatic excitation energies. The lack of a driving force toward the SMLCT/LC minimum, the high fluorescence rate constant of the bright SLC state and its moderately efficient ISC to the triplet manifold explain the experimentally observed dual emission of the Pd complex at room temperature.}, author = {Föller, Jelena and Friese, Daniel H. and Riese, Stefan and Kaminski, Jeremy M. and Metz, Simon and Schmidt, David and Würthner, Frank and Lambert, Christoph and Marian, Christel M.}, journal = {Phys. Chem. Chem. Phys.}, keywords = {myown}, number = 6, pages = {3217-3233}, publisher = {The Royal Society of Chemistry}, title = {On the photophysical properties of IrIII, PtII, and PdII (phenylpyrazole) (phenyldipyrrin) complexes}, volume = 22, year = 2020 }

  %0 Journal Article %1 C9CP05603C %A Föller, Jelena %A Friese, Daniel H. %A Riese, Stefan %A Kaminski, Jeremy M. %A Metz, Simon %A Schmidt, David %A Würthner, Frank %A Lambert, Christoph %A Marian, Christel M. %D 2020 %I The Royal Society of Chemistry %J Phys. Chem. Chem. Phys. %N 6 %P 3217-3233 %R 10.1039/C9CP05603C %T On the photophysical properties of IrIII, PtII, and PdII (phenylpyrazole) (phenyldipyrrin) complexes %U http://dx.doi.org/10.1039/C9CP05603C %V 22 %X The absorption and emission characteristics of (ppz)2(dipy)IrIII, (ppz)(dipy)PtII and (ppz)(dipy)PdII, where ppz stands for phenylpyrazole and dipy for a phenyl meso-substituted dipyrrin ligand, have been investigated by means of combined density functional theory and multireference configuration interaction including scalar relativistic and spin–orbit coupling effects. These results were compared with experimental spectra. The complexes exhibit a high density of low-lying electronically excited states originating from ligand-centered (LC) and metal-to-ligand charge transfer (MLCT) states involving the dipyrrin ligand. In addition, metal-centered (MC) states are found to be low-lying in the Pd complex. In all three cases, the first strong absorption band and the phosphorescence emission band stem from LC excitations on the dipyrrin ligand with small MLCT contributions. The MLCT states show more pronounced relaxation effects than the LC states, with the consequence that the first excited state with predominant singlet multiplicity is of SMLCT/LC type in the heavier Ir and Pt complexes. Substantial spin–orbit coupling between SMLCT/LC and TLC enables fast and efficient intersystem crossing (ISC) and a high triplet quantum yield. Phosphorescence rate constants are rather small in accord with the dominant LC character of the transitions. Out-of-plane distortion promotes nonradiative decay of the excited state population via the MC states thus explaining the lower phosphorescence quantum yield of the Pt complex. The spectral properties of the Pd complex are different in many aspects. Optimization of the S1 state yields a dipyrrin intraligand charge transfer (ILCT) state with highly distorted nuclear arrangement in the butterfly conformers leading to nonradiative deactivation. In contrast, the primarily excited SLC state and the SMLCT/LC state of the twist conformer have nearly equal adiabatic excitation energies. The lack of a driving force toward the SMLCT/LC minimum, the high fluorescence rate constant of the bright SLC state and its moderately efficient ISC to the triplet manifold explain the experimentally observed dual emission of the Pd complex at room temperature.
• Increased Electron Transport and Hole Blocking in an Aqueous Solution Processed Dye-Doped ZnO Cathode Interlayer for High Performance Organic Solar Cells. Luo, Yinqi; Fang, Shaomao; Zheng, Nan; Liu, Linlin; Würthner, Frank; Xie, Zengqi. In ACS Appl. Energy Mater., 3(2), pp. 1694–1701. 2020.
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  In this work, we report high electron transport and hole blocking capability of hybrid photoconductive interlayer materials manufactured from an aqueous solution, which are achieved by doping perylene bisimide dyes into zinc oxide (ZnO) through the formation of ionic bonding between the organic dopants and the inorganic matrix. Benzenesulfonic acid functional groups are introduced to perylene bisimide dye molecules, which enhance the solubility of the dye molecules in water and form ionic bonds with zinc atoms during the fabrication of the hybrid thin films. The ionic bonding assisted molecular dispersion endows the hybrid thin film with full photoconductive properties, which improves electron transport by photoinduced electron transfer from organic dye molecules to the conduction band of ZnO. Especially, the hole blocking ability is also highly increased. Both increased electron transport and hole blocking are benefits to the charge selectivity of the cathode interlayer, which results in a high fill factor in organic solar cells. A power conversion efficiency of up to 15.4% is achieved on the basis of such an aqueous solution processed hybrid interlayer when using PM6:Y6 as the active layer. In addition, the optimized thermal annealing temperature for the fabrication of the hybrid thin film is as low as 150 °C, which is a benefit for the application of such photoconductive materials in flexible devices.

  @article{Luo_2020, abstract = {In this work, we report high electron transport and hole blocking capability of hybrid photoconductive interlayer materials manufactured from an aqueous solution, which are achieved by doping perylene bisimide dyes into zinc oxide (ZnO) through the formation of ionic bonding between the organic dopants and the inorganic matrix. Benzenesulfonic acid functional groups are introduced to perylene bisimide dye molecules, which enhance the solubility of the dye molecules in water and form ionic bonds with zinc atoms during the fabrication of the hybrid thin films. The ionic bonding assisted molecular dispersion endows the hybrid thin film with full photoconductive properties, which improves electron transport by photoinduced electron transfer from organic dye molecules to the conduction band of ZnO. Especially, the hole blocking ability is also highly increased. Both increased electron transport and hole blocking are benefits to the charge selectivity of the cathode interlayer, which results in a high fill factor in organic solar cells. A power conversion efficiency of up to 15.4% is achieved on the basis of such an aqueous solution processed hybrid interlayer when using PM6:Y6 as the active layer. In addition, the optimized thermal annealing temperature for the fabrication of the hybrid thin film is as low as 150 °C, which is a benefit for the application of such photoconductive materials in flexible devices.}, author = {Luo, Yinqi and Fang, Shaomao and Zheng, Nan and Liu, Linlin and Würthner, Frank and Xie, Zengqi}, journal = {ACS Appl. Energy Mater.}, keywords = {myown}, month = {01}, number = 2, pages = {1694–1701}, publisher = {American Chemical Society (ACS)}, title = {Increased Electron Transport and Hole Blocking in an Aqueous Solution Processed Dye-Doped ZnO Cathode Interlayer for High Performance Organic Solar Cells}, volume = 3, year = 2020 }

  %0 Journal Article %1 Luo_2020 %A Luo, Yinqi %A Fang, Shaomao %A Zheng, Nan %A Liu, Linlin %A Würthner, Frank %A Xie, Zengqi %D 2020 %I American Chemical Society (ACS) %J ACS Appl. Energy Mater. %N 2 %P 1694--1701 %R 10.1021/acsaem.9b02176 %T Increased Electron Transport and Hole Blocking in an Aqueous Solution Processed Dye-Doped ZnO Cathode Interlayer for High Performance Organic Solar Cells %U https://doi.org/10.1021%2Facsaem.9b02176 %V 3 %X In this work, we report high electron transport and hole blocking capability of hybrid photoconductive interlayer materials manufactured from an aqueous solution, which are achieved by doping perylene bisimide dyes into zinc oxide (ZnO) through the formation of ionic bonding between the organic dopants and the inorganic matrix. Benzenesulfonic acid functional groups are introduced to perylene bisimide dye molecules, which enhance the solubility of the dye molecules in water and form ionic bonds with zinc atoms during the fabrication of the hybrid thin films. The ionic bonding assisted molecular dispersion endows the hybrid thin film with full photoconductive properties, which improves electron transport by photoinduced electron transfer from organic dye molecules to the conduction band of ZnO. Especially, the hole blocking ability is also highly increased. Both increased electron transport and hole blocking are benefits to the charge selectivity of the cathode interlayer, which results in a high fill factor in organic solar cells. A power conversion efficiency of up to 15.4% is achieved on the basis of such an aqueous solution processed hybrid interlayer when using PM6:Y6 as the active layer. In addition, the optimized thermal annealing temperature for the fabrication of the hybrid thin film is as low as 150 °C, which is a benefit for the application of such photoconductive materials in flexible devices.
• Supramolecular polymerization through kinetic pathway control and living chain growth. Wehner, Marius; Würthner, Frank. In Nature Reviews Chemistry, 4, pp. 38–53. 2020.
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  Supramolecular polymers exhibit fascinating structures, and their properties, and thus applications, depend both on the strength and dynamics of the non-covalent bonds and on the functional properties of the monomeric building blocks. In this Review, we highlight the progress in methods developed to control supramolecular polymerization based on physicochemical insights into the thermodynamics and kinetics of non-covalent interactions. Prerequisites for polymer formation and stability, such as high binding strength (thermodynamics) between complementary receptor units, are briefly discussed, while the main focus is on the kinetic control of pathway selectivity, which in recent years has allowed seed-induced living supramolecular polymerization, chain growth-type supramolecular polymerization and the preparation of specific supramolecular polymer polymorphs and supramolecular block copolymers.

  @article{noauthororeditor, abstract = {Supramolecular polymers exhibit fascinating structures, and their properties, and thus applications, depend both on the strength and dynamics of the non-covalent bonds and on the functional properties of the monomeric building blocks. In this Review, we highlight the progress in methods developed to control supramolecular polymerization based on physicochemical insights into the thermodynamics and kinetics of non-covalent interactions. Prerequisites for polymer formation and stability, such as high binding strength (thermodynamics) between complementary receptor units, are briefly discussed, while the main focus is on the kinetic control of pathway selectivity, which in recent years has allowed seed-induced living supramolecular polymerization, chain growth-type supramolecular polymerization and the preparation of specific supramolecular polymer polymorphs and supramolecular block copolymers.}, author = {Wehner, Marius and Würthner, Frank}, journal = {Nature Reviews Chemistry}, keywords = {myown}, month = {01}, pages = {38-53}, title = {Supramolecular polymerization through kinetic pathway control and living chain growth}, volume = 4, year = 2020 }

  %0 Journal Article %1 noauthororeditor %A Wehner, Marius %A Würthner, Frank %D 2020 %J Nature Reviews Chemistry %P 38-53 %R 10.1038/s41570-019-0153-8 %T Supramolecular polymerization through kinetic pathway control and living chain growth %U https://www.nature.com/articles/s41570-019-0153-8 %V 4 %X Supramolecular polymers exhibit fascinating structures, and their properties, and thus applications, depend both on the strength and dynamics of the non-covalent bonds and on the functional properties of the monomeric building blocks. In this Review, we highlight the progress in methods developed to control supramolecular polymerization based on physicochemical insights into the thermodynamics and kinetics of non-covalent interactions. Prerequisites for polymer formation and stability, such as high binding strength (thermodynamics) between complementary receptor units, are briefly discussed, while the main focus is on the kinetic control of pathway selectivity, which in recent years has allowed seed-induced living supramolecular polymerization, chain growth-type supramolecular polymerization and the preparation of specific supramolecular polymer polymorphs and supramolecular block copolymers.
• A Calix[4]arene-Based Cyclic Dinuclear Ruthenium Complex for Light-Driven Catalytic Water Oxidation. Noll, Niklas; Würthner, Frank. In Chem. Eur. J., 27(1), pp. 444–450. 2020.
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  A cyclic dinuclear ruthenium(bda) (bda: 2,2’‐bipyridine‐6,6’‐dicarboxylate) complex equipped with oligo(ethylene glycol)‐functionalized axial calix[4]arene ligands has been synthesized for homogenous catalytic water oxidation. This novel Ru(bda) macrocycle showed significantly increased catalytic activity in chemical and photocatalytic water oxidation compared to the archetype mononuclear reference [Ru(bda)(pic)2]. Kinetic investigations, including kinetic isotope effect studies, disclosed a unimolecular water nucleophilic attack mechanism of this novel dinuclear water oxidation catalyst (WOC) under the involvement of the second coordination sphere. Photocatalytic water oxidation with this cyclic dinuclear Ru complex using [Ru(bpy)3]Cl2 as a standard photosensitizer revealed a turnover frequency of 15.5 s−1 and a turnover number of 460. This so far highest photocatalytic performance reported for a Ru(bda) complex underlines the potential of this water‐soluble WOC for artificial photosynthesis.

  @article{Noll_2020, abstract = {A cyclic dinuclear ruthenium(bda) (bda: 2,2’‐bipyridine‐6,6’‐dicarboxylate) complex equipped with oligo(ethylene glycol)‐functionalized axial calix[4]arene ligands has been synthesized for homogenous catalytic water oxidation. This novel Ru(bda) macrocycle showed significantly increased catalytic activity in chemical and photocatalytic water oxidation compared to the archetype mononuclear reference [Ru(bda)(pic)2]. Kinetic investigations, including kinetic isotope effect studies, disclosed a unimolecular water nucleophilic attack mechanism of this novel dinuclear water oxidation catalyst (WOC) under the involvement of the second coordination sphere. Photocatalytic water oxidation with this cyclic dinuclear Ru complex using [Ru(bpy)3]Cl2 as a standard photosensitizer revealed a turnover frequency of 15.5 s−1 and a turnover number of 460. This so far highest photocatalytic performance reported for a Ru(bda) complex underlines the potential of this water‐soluble WOC for artificial photosynthesis.}, author = {Noll, Niklas and Würthner, Frank}, journal = {Chem. Eur. J.}, keywords = {myown}, month = 11, number = 1, pages = {444–450}, publisher = {Wiley}, title = {A Calix[4]arene-Based Cyclic Dinuclear Ruthenium Complex for Light-Driven Catalytic Water Oxidation}, volume = 27, year = 2020 }

  %0 Journal Article %1 Noll_2020 %A Noll, Niklas %A Würthner, Frank %D 2020 %I Wiley %J Chem. Eur. J. %N 1 %P 444--450 %R 10.1002/chem.202004486 %T A Calix[4]arene-Based Cyclic Dinuclear Ruthenium Complex for Light-Driven Catalytic Water Oxidation %U https://doi.org/10.1002%2Fchem.202004486 %V 27 %X A cyclic dinuclear ruthenium(bda) (bda: 2,2’‐bipyridine‐6,6’‐dicarboxylate) complex equipped with oligo(ethylene glycol)‐functionalized axial calix[4]arene ligands has been synthesized for homogenous catalytic water oxidation. This novel Ru(bda) macrocycle showed significantly increased catalytic activity in chemical and photocatalytic water oxidation compared to the archetype mononuclear reference [Ru(bda)(pic)2]. Kinetic investigations, including kinetic isotope effect studies, disclosed a unimolecular water nucleophilic attack mechanism of this novel dinuclear water oxidation catalyst (WOC) under the involvement of the second coordination sphere. Photocatalytic water oxidation with this cyclic dinuclear Ru complex using [Ru(bpy)3]Cl2 as a standard photosensitizer revealed a turnover frequency of 15.5 s−1 and a turnover number of 460. This so far highest photocatalytic performance reported for a Ru(bda) complex underlines the potential of this water‐soluble WOC for artificial photosynthesis.
• Crystal Engineering of 1D Exciton Systems Composed of Single- and Double-Stranded Perylene Bisimide J-Aggregates. Stolte, Matthias; Hecht, Reinhard; Xie, Zengqi; Liu, Linlin; Kaufmann, Christina; Kudzus, Astrid; Schmidt, David; Würthner, Frank. In Adv. Opt. Mater., 8(18), p. 2000926. 2020.
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  Single crystals of three at bay area tetraphenoxy‐substituted perylene bisimide dyes are grown by vacuum sublimation. X‐ray analysis reveals the self‐assembly of these highly twisted perylene bisimides (PBIs) in the solid state via imide–imide hydrogen bonding into hydrogen‐bonded PBI chains. The crystallographic insights disclose that the conformation and sterical congestion imparted by the phenoxy substituents can be controlled by ortho‐substituents. Accordingly, whilst sterically less demanding methyl and isopropyl substituents afford double‐stranded PBI chains of complementary P and M atropo‐enantiomers, single hydrogen‐bonded chains of homochiral PBIs are observed for the sterically more demanding ortho‐phenyl substituents. Investigation of the absorption and fluorescence properties of microcrystals and thin films of these PBIs allow for an unambiguous interpretation of these exciton systems. Thus, the J‐aggregates of the double‐stranded crystals exhibit a much larger (negative) exciton coupling than the single‐stranded one, which in contrast has the higher solid‐state fluorescence quantum yield.

  @article{Stolte_2020, abstract = {Single crystals of three at bay area tetraphenoxy‐substituted perylene bisimide dyes are grown by vacuum sublimation. X‐ray analysis reveals the self‐assembly of these highly twisted perylene bisimides (PBIs) in the solid state via imide–imide hydrogen bonding into hydrogen‐bonded PBI chains. The crystallographic insights disclose that the conformation and sterical congestion imparted by the phenoxy substituents can be controlled by ortho‐substituents. Accordingly, whilst sterically less demanding methyl and isopropyl substituents afford double‐stranded PBI chains of complementary P and M atropo‐enantiomers, single hydrogen‐bonded chains of homochiral PBIs are observed for the sterically more demanding ortho‐phenyl substituents. Investigation of the absorption and fluorescence properties of microcrystals and thin films of these PBIs allow for an unambiguous interpretation of these exciton systems. Thus, the J‐aggregates of the double‐stranded crystals exhibit a much larger (negative) exciton coupling than the single‐stranded one, which in contrast has the higher solid‐state fluorescence quantum yield.}, author = {Stolte, Matthias and Hecht, Reinhard and Xie, Zengqi and Liu, Linlin and Kaufmann, Christina and Kudzus, Astrid and Schmidt, David and Würthner, Frank}, journal = {Adv. Opt. Mater.}, keywords = {myown}, month = {06}, number = 18, pages = 2000926, publisher = {Wiley}, title = {Crystal Engineering of 1D Exciton Systems Composed of Single- and Double-Stranded Perylene Bisimide J-Aggregates}, volume = 8, year = 2020 }

  %0 Journal Article %1 Stolte_2020 %A Stolte, Matthias %A Hecht, Reinhard %A Xie, Zengqi %A Liu, Linlin %A Kaufmann, Christina %A Kudzus, Astrid %A Schmidt, David %A Würthner, Frank %D 2020 %I Wiley %J Adv. Opt. Mater. %N 18 %P 2000926 %R 10.1002/adom.202000926 %T Crystal Engineering of 1D Exciton Systems Composed of Single- and Double-Stranded Perylene Bisimide J-Aggregates %U https://doi.org/10.1002%2Fadom.202000926 %V 8 %X Single crystals of three at bay area tetraphenoxy‐substituted perylene bisimide dyes are grown by vacuum sublimation. X‐ray analysis reveals the self‐assembly of these highly twisted perylene bisimides (PBIs) in the solid state via imide–imide hydrogen bonding into hydrogen‐bonded PBI chains. The crystallographic insights disclose that the conformation and sterical congestion imparted by the phenoxy substituents can be controlled by ortho‐substituents. Accordingly, whilst sterically less demanding methyl and isopropyl substituents afford double‐stranded PBI chains of complementary P and M atropo‐enantiomers, single hydrogen‐bonded chains of homochiral PBIs are observed for the sterically more demanding ortho‐phenyl substituents. Investigation of the absorption and fluorescence properties of microcrystals and thin films of these PBIs allow for an unambiguous interpretation of these exciton systems. Thus, the J‐aggregates of the double‐stranded crystals exhibit a much larger (negative) exciton coupling than the single‐stranded one, which in contrast has the higher solid‐state fluorescence quantum yield.
• Trapped Exciton and Large Birefringence in Cl2–NDI Revealed by Optical Spectroscopy. Pinteric, Marko; Roh, Seulki; Uykur, Ece; Hansen, Nis Hauke; Pflaum, Jens; Stolte, Matthias; Würthner, Frank; Dressel, Martin. In The Journal of Physical Chemistry C, 124(32), pp. 17829–17835. 2020.
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  The n-type organic semiconductor, β-phase single crystalline dichloro naphthalene diimide, Cl2–NDI, is investigated in a broad frequency range via optical spectroscopy. The temperature-dependent absorbance spectra reveal the appearance of new molecular vibration modes; several of them exhibit a pronounced splitting and abnormal red shift. In the visible spectral range, we observe a splitting of the J-band upon cooling, which we attributed to self-trapped excitons via coupling between free excitons and molecular vibrations or trapping by disorder induced Lévy states. Additionally, we discover a strong birefringence of these crystals by pronounced polarization beat over a wide frequency range.

  @article{Pinteri__2020, abstract = {The n-type organic semiconductor, β-phase single crystalline dichloro naphthalene diimide, Cl2–NDI, is investigated in a broad frequency range via optical spectroscopy. The temperature-dependent absorbance spectra reveal the appearance of new molecular vibration modes; several of them exhibit a pronounced splitting and abnormal red shift. In the visible spectral range, we observe a splitting of the J-band upon cooling, which we attributed to self-trapped excitons via coupling between free excitons and molecular vibrations or trapping by disorder induced Lévy states. Additionally, we discover a strong birefringence of these crystals by pronounced polarization beat over a wide frequency range.}, author = {Pinteric, Marko and Roh, Seulki and Uykur, Ece and Hansen, Nis Hauke and Pflaum, Jens and Stolte, Matthias and Würthner, Frank and Dressel, Martin}, journal = {The Journal of Physical Chemistry C}, keywords = {myown}, month = {07}, number = 32, pages = {17829–17835}, publisher = {American Chemical Society ({ACS})}, title = {Trapped Exciton and Large Birefringence in Cl2–NDI Revealed by Optical Spectroscopy}, volume = 124, year = 2020 }

  %0 Journal Article %1 Pinteri__2020 %A Pinteric, Marko %A Roh, Seulki %A Uykur, Ece %A Hansen, Nis Hauke %A Pflaum, Jens %A Stolte, Matthias %A Würthner, Frank %A Dressel, Martin %D 2020 %I American Chemical Society (ACS) %J The Journal of Physical Chemistry C %N 32 %P 17829--17835 %R 10.1021/acs.jpcc.0c05165 %T Trapped Exciton and Large Birefringence in Cl2–NDI Revealed by Optical Spectroscopy %U https://doi.org/10.1021%2Facs.jpcc.0c05165 %V 124 %X The n-type organic semiconductor, β-phase single crystalline dichloro naphthalene diimide, Cl2–NDI, is investigated in a broad frequency range via optical spectroscopy. The temperature-dependent absorbance spectra reveal the appearance of new molecular vibration modes; several of them exhibit a pronounced splitting and abnormal red shift. In the visible spectral range, we observe a splitting of the J-band upon cooling, which we attributed to self-trapped excitons via coupling between free excitons and molecular vibrations or trapping by disorder induced Lévy states. Additionally, we discover a strong birefringence of these crystals by pronounced polarization beat over a wide frequency range.
• Aggregation-Induced Emission (AIE): A Historical Perspective. Würthner, Frank. In Angew. Chem. Int. Ed., 59(34), pp. 14192–14196. 2020.
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  @article{W_rthner_2020, author = {Würthner, Frank}, journal = {Angew. Chem. Int. Ed.}, keywords = {myown}, month = {07}, number = 34, pages = {14192–14196}, publisher = {Wiley}, title = {Aggregation-Induced Emission (AIE): A Historical Perspective}, volume = 59, year = 2020 }

  %0 Journal Article %1 W_rthner_2020 %A Würthner, Frank %D 2020 %I Wiley %J Angew. Chem. Int. Ed. %N 34 %P 14192--14196 %R 10.1002/anie.202007525 %T Aggregation-Induced Emission (AIE): A Historical Perspective %U https://doi.org/10.1002%2Fanie.202007525 %V 59
• Perylene Bisimide Cyclophanes: Structure–Property Relationships upon Variation of the Cavity Size. Rühe, Jessica; Bialas, David; Spenst, Peter; Krause, Ana-Maria; Würthner, Frank. In Organic Materials, 2, pp. 149–158. 2020.
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  Five cyclophanes composed of two perylene bisimide (PBI)dyes and various CH2–arylene–CH2linker units were synthesized. PM6-D3H4 geometry-optimized structures and a single crystal for one ofthese cyclophanes reveal well-defined distances between the twocoplanar PBI units in these cyclophanes, spanning the range from 5.0 to12.5 Å. UV/vis absorption spectra reveal a redistribution of oscillatorstrength of the vibronic bands due to a H-type exciton coupling even forthe cyclophane with the largest interchromophoric distance. Aquantitative evaluation according to the Kasha–Spano theory affordsexciton coupling strengths ranging from 64 cm�1for the largestcyclophane up to 333 cm�1for the smallest one and a surprisingly goodfit to the cubic interchromophoric distance in the framework of thepoint-dipole approximation. Interchromophoric interaction is alsonoticed influorescence lifetimes that are significantly increased forallfive cyclophanes as expected for H-coupled chromophores due to adecrease of the radiative rate. For the three largest cyclophanes withinterchromophoric distances of>9Å,fluorescence quantum yieldsremain high in chloroform (>88%), whilst for the smaller ones withinterchromophoric distances<6 Å, additional nonradiative pathwayslead to a pronouncedfluorescence quenching.

  @article{ruhe2020perylene, abstract = {Five cyclophanes composed of two perylene bisimide (PBI)dyes and various CH2–arylene–CH2linker units were synthesized. PM6-D3H4 geometry-optimized structures and a single crystal for one ofthese cyclophanes reveal well-defined distances between the twocoplanar PBI units in these cyclophanes, spanning the range from 5.0 to12.5 Å. UV/vis absorption spectra reveal a redistribution of oscillatorstrength of the vibronic bands due to a H-type exciton coupling even forthe cyclophane with the largest interchromophoric distance. Aquantitative evaluation according to the Kasha–Spano theory affordsexciton coupling strengths ranging from 64 cm�1for the largestcyclophane up to 333 cm�1for the smallest one and a surprisingly goodfit to the cubic interchromophoric distance in the framework of thepoint-dipole approximation. Interchromophoric interaction is alsonoticed influorescence lifetimes that are significantly increased forallfive cyclophanes as expected for H-coupled chromophores due to adecrease of the radiative rate. For the three largest cyclophanes withinterchromophoric distances of>9Å,fluorescence quantum yieldsremain high in chloroform (>88%), whilst for the smaller ones withinterchromophoric distances<6 Å, additional nonradiative pathwayslead to a pronouncedfluorescence quenching.}, author = {Rühe, Jessica and Bialas, David and Spenst, Peter and Krause, Ana-Maria and Würthner, Frank}, journal = {Organic Materials}, keywords = {myown}, month = {04}, pages = {149-158}, title = {Perylene Bisimide Cyclophanes: Structure–Property Relationships upon Variation of the Cavity Size}, volume = 2, year = 2020 }

  %0 Journal Article %1 ruhe2020perylene %A Rühe, Jessica %A Bialas, David %A Spenst, Peter %A Krause, Ana-Maria %A Würthner, Frank %D 2020 %J Organic Materials %P 149-158 %R 10.1055/s-0040-1709998 %T Perylene Bisimide Cyclophanes: Structure–Property Relationships upon Variation of the Cavity Size %U https://www.thieme-connect.de/products/ejournals/abstract/10.1055/s-0040-1709998 %V 2 %X Five cyclophanes composed of two perylene bisimide (PBI)dyes and various CH2–arylene–CH2linker units were synthesized. PM6-D3H4 geometry-optimized structures and a single crystal for one ofthese cyclophanes reveal well-defined distances between the twocoplanar PBI units in these cyclophanes, spanning the range from 5.0 to12.5 Å. UV/vis absorption spectra reveal a redistribution of oscillatorstrength of the vibronic bands due to a H-type exciton coupling even forthe cyclophane with the largest interchromophoric distance. Aquantitative evaluation according to the Kasha–Spano theory affordsexciton coupling strengths ranging from 64 cm�1for the largestcyclophane up to 333 cm�1for the smallest one and a surprisingly goodfit to the cubic interchromophoric distance in the framework of thepoint-dipole approximation. Interchromophoric interaction is alsonoticed influorescence lifetimes that are significantly increased forallfive cyclophanes as expected for H-coupled chromophores due to adecrease of the radiative rate. For the three largest cyclophanes withinterchromophoric distances of>9Å,fluorescence quantum yieldsremain high in chloroform (>88%), whilst for the smaller ones withinterchromophoric distances<6 Å, additional nonradiative pathwayslead to a pronouncedfluorescence quenching.
• Persistent Room Temperature Phosphorescence from Triarylboranes: A Combined Experimental and Theoretical Study. Wu, Zhu; Nitsch, Jörn; Schuster, Julia; Friedrich, Alexandra; Edkins, Katharina; Loebnitz, Marcel; Dinkelbach, Fabian; Stepanenko, Vladimir; Würthner, Frank; Marian, Christel M.; Ji, Lei; Marder, Todd B. In Angew. Chem. Int. Ed., 59(39), pp. 17137–17144. 2020.
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  Achieving highly efficient phosphorescence in purely organic luminophors at room temperature remains a major challenge due to slow intersystem crossing (ISC) rates in combination with effective non‐radiative processes in those systems. Most room temperature phosphorescent (RTP) organic materials have O‐ or N‐lone pairs leading to low lying (n, π*) and (π, π*) excited states which accelerate kisc through El‐Sayed's rule. Herein, we report the first persistent RTP with lifetimes up to 0.5 s from simple triarylboranes which have no lone pairs. RTP is only observed in the crystalline state and in highly doped PMMA films which are indicative of aggregation induced emission (AIE). Detailed crystal structure analysis suggested that intermolecular interactions are important for efficient RTP. Furthermore, photophysical studies of the isolated molecules in a frozen glass, in combination with DFT/MRCI calculations, show that (σ, B p)→(π, B p) transitions accelerate the ISC process. This work provides a new approach for the design of RTP materials without (n, π*) transitions.

  @article{Wu_2020, abstract = {Achieving highly efficient phosphorescence in purely organic luminophors at room temperature remains a major challenge due to slow intersystem crossing (ISC) rates in combination with effective non‐radiative processes in those systems. Most room temperature phosphorescent (RTP) organic materials have O‐ or N‐lone pairs leading to low lying (n, π*) and (π, π*) excited states which accelerate kisc through El‐Sayed's rule. Herein, we report the first persistent RTP with lifetimes up to 0.5 s from simple triarylboranes which have no lone pairs. RTP is only observed in the crystalline state and in highly doped PMMA films which are indicative of aggregation induced emission (AIE). Detailed crystal structure analysis suggested that intermolecular interactions are important for efficient RTP. Furthermore, photophysical studies of the isolated molecules in a frozen glass, in combination with DFT/MRCI calculations, show that (σ, B p)→(π, B p) transitions accelerate the ISC process. This work provides a new approach for the design of RTP materials without (n, π*) transitions.}, author = {Wu, Zhu and Nitsch, Jörn and Schuster, Julia and Friedrich, Alexandra and Edkins, Katharina and Loebnitz, Marcel and Dinkelbach, Fabian and Stepanenko, Vladimir and Würthner, Frank and Marian, Christel M. and Ji, Lei and Marder, Todd B.}, journal = {Angew. Chem. Int. Ed.}, keywords = {myown}, month = {08}, number = 39, pages = {17137-17144}, publisher = {Wiley}, title = {Persistent Room Temperature Phosphorescence from Triarylboranes: A Combined Experimental and Theoretical Study}, volume = 59, year = 2020 }

  %0 Journal Article %1 Wu_2020 %A Wu, Zhu %A Nitsch, Jörn %A Schuster, Julia %A Friedrich, Alexandra %A Edkins, Katharina %A Loebnitz, Marcel %A Dinkelbach, Fabian %A Stepanenko, Vladimir %A Würthner, Frank %A Marian, Christel M. %A Ji, Lei %A Marder, Todd B. %D 2020 %I Wiley %J Angew. Chem. Int. Ed. %N 39 %P 17137-17144 %R 10.1002/anie.202007610 %T Persistent Room Temperature Phosphorescence from Triarylboranes: A Combined Experimental and Theoretical Study %U https://doi.org/10.1002%2Fanie.202007610 %V 59 %X Achieving highly efficient phosphorescence in purely organic luminophors at room temperature remains a major challenge due to slow intersystem crossing (ISC) rates in combination with effective non‐radiative processes in those systems. Most room temperature phosphorescent (RTP) organic materials have O‐ or N‐lone pairs leading to low lying (n, π*) and (π, π*) excited states which accelerate kisc through El‐Sayed's rule. Herein, we report the first persistent RTP with lifetimes up to 0.5 s from simple triarylboranes which have no lone pairs. RTP is only observed in the crystalline state and in highly doped PMMA films which are indicative of aggregation induced emission (AIE). Detailed crystal structure analysis suggested that intermolecular interactions are important for efficient RTP. Furthermore, photophysical studies of the isolated molecules in a frozen glass, in combination with DFT/MRCI calculations, show that (σ, B p)→(π, B p) transitions accelerate the ISC process. This work provides a new approach for the design of RTP materials without (n, π*) transitions.
• Efficient Multiexciton State Generation in Charge-Transfer-Coupled Perylene Bisimide Dimers via Structural Control. Hong, Yongseok; Kim, Juno; Kim, Woojae; Kaufmann, Christina; Kim, Hyungjun; Würthner, Frank; Kim, Dongho. In J. Am. Chem. Soc., 142(17), pp. 7845–7857. 2020.
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  The singlet fission (SF) process is generally defined as the conversion of one singlet exciton (S1) into two triplet excitons (2·T1), which has the potential to overcome thermalization losses in the field of photovoltaic devices. Among the applicable compounds for SF-based photovoltaic devices, perylene bisimide (PBI) is one of the best candidates because of its electronic tunability and photostability. However, the strategy for efficient SF in PBIs remains ambiguous because of numerous competing relaxation pathways in PBI-based molecular materials. In this regard, for the first time, we observed the SF mechanism in PBI dimers by controlling the intrinsic factor (exciton coupling) and the external environment (solvent polarity and viscosity). Time-resolved spectroscopic measurements and quantum chemical simulations reveal that efficient SF occurs through the charge-transfer-assisted mechanism, entailing a large structural fluctuation. Our findings not only highlight the SF mechanism in PBI dimers but also suggest the factors responsible for an efficient SF process, which are important considerations in the design of molecular materials for photovoltaic devices.

  @article{Hong_2020, abstract = {The singlet fission (SF) process is generally defined as the conversion of one singlet exciton (S1) into two triplet excitons (2·T1), which has the potential to overcome thermalization losses in the field of photovoltaic devices. Among the applicable compounds for SF-based photovoltaic devices, perylene bisimide (PBI) is one of the best candidates because of its electronic tunability and photostability. However, the strategy for efficient SF in PBIs remains ambiguous because of numerous competing relaxation pathways in PBI-based molecular materials. In this regard, for the first time, we observed the SF mechanism in PBI dimers by controlling the intrinsic factor (exciton coupling) and the external environment (solvent polarity and viscosity). Time-resolved spectroscopic measurements and quantum chemical simulations reveal that efficient SF occurs through the charge-transfer-assisted mechanism, entailing a large structural fluctuation. Our findings not only highlight the SF mechanism in PBI dimers but also suggest the factors responsible for an efficient SF process, which are important considerations in the design of molecular materials for photovoltaic devices.}, author = {Hong, Yongseok and Kim, Juno and Kim, Woojae and Kaufmann, Christina and Kim, Hyungjun and Würthner, Frank and Kim, Dongho}, journal = {J. Am. Chem. Soc.}, keywords = {myown}, month = {04}, number = 17, pages = {7845–7857}, publisher = {American Chemical Society ({ACS})}, title = {Efficient Multiexciton State Generation in Charge-Transfer-Coupled Perylene Bisimide Dimers via Structural Control}, volume = 142, year = 2020 }

  %0 Journal Article %1 Hong_2020 %A Hong, Yongseok %A Kim, Juno %A Kim, Woojae %A Kaufmann, Christina %A Kim, Hyungjun %A Würthner, Frank %A Kim, Dongho %D 2020 %I American Chemical Society (ACS) %J J. Am. Chem. Soc. %N 17 %P 7845--7857 %R 10.1021/jacs.0c00870 %T Efficient Multiexciton State Generation in Charge-Transfer-Coupled Perylene Bisimide Dimers via Structural Control %U https://doi.org/10.1021%2Fjacs.0c00870 %V 142 %X The singlet fission (SF) process is generally defined as the conversion of one singlet exciton (S1) into two triplet excitons (2·T1), which has the potential to overcome thermalization losses in the field of photovoltaic devices. Among the applicable compounds for SF-based photovoltaic devices, perylene bisimide (PBI) is one of the best candidates because of its electronic tunability and photostability. However, the strategy for efficient SF in PBIs remains ambiguous because of numerous competing relaxation pathways in PBI-based molecular materials. In this regard, for the first time, we observed the SF mechanism in PBI dimers by controlling the intrinsic factor (exciton coupling) and the external environment (solvent polarity and viscosity). Time-resolved spectroscopic measurements and quantum chemical simulations reveal that efficient SF occurs through the charge-transfer-assisted mechanism, entailing a large structural fluctuation. Our findings not only highlight the SF mechanism in PBI dimers but also suggest the factors responsible for an efficient SF process, which are important considerations in the design of molecular materials for photovoltaic devices.
• Supramolecularly Engineered J-Aggregates Based on Perylene Bisimide Dyes. Hecht, Markus; Würthner, Frank. In Accounts of Chemical Research, 54(3), pp. 642–653. 2020.
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  The discovery of the self-assembly of cyanine dyes into J-aggregates had a major impact on the development of dye chemistry due to the emergence of new useful properties in the aggregated state. The unique optical features of these J-aggregates are narrowed, bathochromically shifted absorption bands with almost resonant fluorescence with an increased radiative rate that results from the coherently coupled molecular transition dipoles arranged in a slip-stacked fashion. Because of their desirable properties, J-aggregates gained popularity in the field of functional materials and enabled the efficient photosensitization of silver halide grains in color photography. However, despite a good theoretical understanding of structure–property relationships by the molecular exciton model, further examples of J-aggregates remained scarce for a long time as supramolecular designs to guide the formation of dye aggregates into the required slip-stacked arrangement were lacking. Drawing inspiration from the bacteriochlorophyll c self-organization found in the chlorosomal light-harvesting antennas of green sulfur bacteria, we envisioned the use of nature’s supramolecular blueprint to develop J-aggregates of perylene bisimides (PBIs). This class of materials is applied in high-performance color pigments and as n-type organic semiconductors in transistors and solar cells. Combining outstanding photochemical and thermal stability, high tinctorial strength and excellent fluorescence, PBIs are therefore an ideal model system for the preparation of J-aggregates with a wide range of potential applications. In this Account, we elucidate how a combination of steric constraints and hydrogen bonding receptor sites can guide the self-assembly of PBI dyes into slip-stacked packing motifs with J-type exciton coupling. We will discuss the supramolecular polymerization of multiple hydrogen-bonded PBI strands in organic and aqueous media and how minor structural modifications in monomeric PBI molecules can be used to obtain near-infrared absorbing J-aggregates, organogels, or thermoresponsive hydrogels. Pushing the boundaries of self-assembly into the bulk, engineering of the substituents’ steric requirements by a dendron-wedge approach afforded adjustable numbers of helical strands of PBI J-aggregates in the columnar liquid-crystalline state and the preparation of lamellar phases. To fully explore their potential, we have studied PBI J-aggregates in collaborative work with spectroscopists, physicists, and theoreticians. In this way, exciton migration over distances of up to 180 nm was shown, and insights into the influence of static disorder on the transport of excitation energy in PBI J-aggregates were derived. Furthermore, the application of PBI J-aggregates as functional materials was demonstrated in photonic microcavities, thin-film transistors, and organic solar cells.

  @article{Hecht_2020, abstract = {The discovery of the self-assembly of cyanine dyes into J-aggregates had a major impact on the development of dye chemistry due to the emergence of new useful properties in the aggregated state. The unique optical features of these J-aggregates are narrowed, bathochromically shifted absorption bands with almost resonant fluorescence with an increased radiative rate that results from the coherently coupled molecular transition dipoles arranged in a slip-stacked fashion. Because of their desirable properties, J-aggregates gained popularity in the field of functional materials and enabled the efficient photosensitization of silver halide grains in color photography. However, despite a good theoretical understanding of structure–property relationships by the molecular exciton model, further examples of J-aggregates remained scarce for a long time as supramolecular designs to guide the formation of dye aggregates into the required slip-stacked arrangement were lacking. Drawing inspiration from the bacteriochlorophyll c self-organization found in the chlorosomal light-harvesting antennas of green sulfur bacteria, we envisioned the use of nature’s supramolecular blueprint to develop J-aggregates of perylene bisimides (PBIs). This class of materials is applied in high-performance color pigments and as n-type organic semiconductors in transistors and solar cells. Combining outstanding photochemical and thermal stability, high tinctorial strength and excellent fluorescence, PBIs are therefore an ideal model system for the preparation of J-aggregates with a wide range of potential applications. In this Account, we elucidate how a combination of steric constraints and hydrogen bonding receptor sites can guide the self-assembly of PBI dyes into slip-stacked packing motifs with J-type exciton coupling. We will discuss the supramolecular polymerization of multiple hydrogen-bonded PBI strands in organic and aqueous media and how minor structural modifications in monomeric PBI molecules can be used to obtain near-infrared absorbing J-aggregates, organogels, or thermoresponsive hydrogels. Pushing the boundaries of self-assembly into the bulk, engineering of the substituents’ steric requirements by a dendron-wedge approach afforded adjustable numbers of helical strands of PBI J-aggregates in the columnar liquid-crystalline state and the preparation of lamellar phases. To fully explore their potential, we have studied PBI J-aggregates in collaborative work with spectroscopists, physicists, and theoreticians. In this way, exciton migration over distances of up to 180 nm was shown, and insights into the influence of static disorder on the transport of excitation energy in PBI J-aggregates were derived. Furthermore, the application of PBI J-aggregates as functional materials was demonstrated in photonic microcavities, thin-film transistors, and organic solar cells.}, author = {Hecht, Markus and Würthner, Frank}, journal = {Accounts of Chemical Research}, keywords = {myown}, month = 12, number = 3, pages = {642-653}, publisher = {American Chemical Society ({ACS})}, title = {Supramolecularly Engineered J-Aggregates Based on Perylene Bisimide Dyes}, volume = 54, year = 2020 }

  %0 Journal Article %1 Hecht_2020 %A Hecht, Markus %A Würthner, Frank %D 2020 %I American Chemical Society (ACS) %J Accounts of Chemical Research %N 3 %P 642-653 %R 10.1021/acs.accounts.0c00590 %T Supramolecularly Engineered J-Aggregates Based on Perylene Bisimide Dyes %U https://doi.org/10.1021%2Facs.accounts.0c00590 %V 54 %X The discovery of the self-assembly of cyanine dyes into J-aggregates had a major impact on the development of dye chemistry due to the emergence of new useful properties in the aggregated state. The unique optical features of these J-aggregates are narrowed, bathochromically shifted absorption bands with almost resonant fluorescence with an increased radiative rate that results from the coherently coupled molecular transition dipoles arranged in a slip-stacked fashion. Because of their desirable properties, J-aggregates gained popularity in the field of functional materials and enabled the efficient photosensitization of silver halide grains in color photography. However, despite a good theoretical understanding of structure–property relationships by the molecular exciton model, further examples of J-aggregates remained scarce for a long time as supramolecular designs to guide the formation of dye aggregates into the required slip-stacked arrangement were lacking. Drawing inspiration from the bacteriochlorophyll c self-organization found in the chlorosomal light-harvesting antennas of green sulfur bacteria, we envisioned the use of nature’s supramolecular blueprint to develop J-aggregates of perylene bisimides (PBIs). This class of materials is applied in high-performance color pigments and as n-type organic semiconductors in transistors and solar cells. Combining outstanding photochemical and thermal stability, high tinctorial strength and excellent fluorescence, PBIs are therefore an ideal model system for the preparation of J-aggregates with a wide range of potential applications. In this Account, we elucidate how a combination of steric constraints and hydrogen bonding receptor sites can guide the self-assembly of PBI dyes into slip-stacked packing motifs with J-type exciton coupling. We will discuss the supramolecular polymerization of multiple hydrogen-bonded PBI strands in organic and aqueous media and how minor structural modifications in monomeric PBI molecules can be used to obtain near-infrared absorbing J-aggregates, organogels, or thermoresponsive hydrogels. Pushing the boundaries of self-assembly into the bulk, engineering of the substituents’ steric requirements by a dendron-wedge approach afforded adjustable numbers of helical strands of PBI J-aggregates in the columnar liquid-crystalline state and the preparation of lamellar phases. To fully explore their potential, we have studied PBI J-aggregates in collaborative work with spectroscopists, physicists, and theoreticians. In this way, exciton migration over distances of up to 180 nm was shown, and insights into the influence of static disorder on the transport of excitation energy in PBI J-aggregates were derived. Furthermore, the application of PBI J-aggregates as functional materials was demonstrated in photonic microcavities, thin-film transistors, and organic solar cells.
• 1-Mono- and 1,7-Disubstituted Perylene Bisimide Dyes with Voluminous Groups at Bay Positions: In Search for Highly Effective Solid-State Fluorescence Materials. Stolte, Matthias; Schembri, Tim; Süß, Jasmin; Schmidt, David; Krause, Ana-Maria; Vysotsky, Myroslav O.; Würthner, Frank. In Chem. Mater., 32(14), pp. 6222–6236. 2020.
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  A series of 1-mono- and 1,7-disubstituted perylene bisimides (PBIs) with voluminous phenoxy groups at bay positions has been synthesized. These dyes show absorption and emission properties typical for PBIs in solution with high fluorescence quantum yields close to unity. In the solid state, the voluminous substituents at bay positions effectively wrap the dye core and prevent π–π interactions between twofold substituted chromophores. The comparison of UV–vis absorption and fluorescence properties for solutions as well as solid-state thin films, powders, and microcrystals in combination with the respective single-crystal structures allows for establishing the packing structure–optical property relationships. According to this analysis, only with two bulky 2,4,6-tris(4-tert-butylphenyl)-phenoxy or 2,4,6-tris(3,5-di-tert-butylphenyl)-phenoxy substituents functionalized PBI chromophores are completely jacketed to afford efficient solid-state emitter materials with fluorescence quantum yields of over 60%. A comparative evaluation of PBIs bearing bulky substituents at imide positions reveals significantly higher solid-state fluorescence quantum yields of the 1,7-substituted PBIs.

  @article{Stolte_2020, abstract = {A series of 1-mono- and 1,7-disubstituted perylene bisimides (PBIs) with voluminous phenoxy groups at bay positions has been synthesized. These dyes show absorption and emission properties typical for PBIs in solution with high fluorescence quantum yields close to unity. In the solid state, the voluminous substituents at bay positions effectively wrap the dye core and prevent π–π interactions between twofold substituted chromophores. The comparison of UV–vis absorption and fluorescence properties for solutions as well as solid-state thin films, powders, and microcrystals in combination with the respective single-crystal structures allows for establishing the packing structure–optical property relationships. According to this analysis, only with two bulky 2,4,6-tris(4-tert-butylphenyl)-phenoxy or 2,4,6-tris(3,5-di-tert-butylphenyl)-phenoxy substituents functionalized PBI chromophores are completely jacketed to afford efficient solid-state emitter materials with fluorescence quantum yields of over 60%. A comparative evaluation of PBIs bearing bulky substituents at imide positions reveals significantly higher solid-state fluorescence quantum yields of the 1,7-substituted PBIs.}, author = {Stolte, Matthias and Schembri, Tim and Süß, Jasmin and Schmidt, David and Krause, Ana-Maria and Vysotsky, Myroslav O. and Würthner, Frank}, journal = {Chem. Mater.}, keywords = {myown}, month = {06}, number = 14, pages = {6222–6236}, publisher = {American Chemical Society ({ACS})}, title = {1-Mono- and 1,7-Disubstituted Perylene Bisimide Dyes with Voluminous Groups at Bay Positions: In Search for Highly Effective Solid-State Fluorescence Materials}, volume = 32, year = 2020 }

  %0 Journal Article %1 Stolte_2020 %A Stolte, Matthias %A Schembri, Tim %A Süß, Jasmin %A Schmidt, David %A Krause, Ana-Maria %A Vysotsky, Myroslav O. %A Würthner, Frank %D 2020 %I American Chemical Society (ACS) %J Chem. Mater. %N 14 %P 6222--6236 %R 10.1021/acs.chemmater.0c02115 %T 1-Mono- and 1,7-Disubstituted Perylene Bisimide Dyes with Voluminous Groups at Bay Positions: In Search for Highly Effective Solid-State Fluorescence Materials %U https://doi.org/10.1021%2Facs.chemmater.0c02115 %V 32 %X A series of 1-mono- and 1,7-disubstituted perylene bisimides (PBIs) with voluminous phenoxy groups at bay positions has been synthesized. These dyes show absorption and emission properties typical for PBIs in solution with high fluorescence quantum yields close to unity. In the solid state, the voluminous substituents at bay positions effectively wrap the dye core and prevent π–π interactions between twofold substituted chromophores. The comparison of UV–vis absorption and fluorescence properties for solutions as well as solid-state thin films, powders, and microcrystals in combination with the respective single-crystal structures allows for establishing the packing structure–optical property relationships. According to this analysis, only with two bulky 2,4,6-tris(4-tert-butylphenyl)-phenoxy or 2,4,6-tris(3,5-di-tert-butylphenyl)-phenoxy substituents functionalized PBI chromophores are completely jacketed to afford efficient solid-state emitter materials with fluorescence quantum yields of over 60%. A comparative evaluation of PBIs bearing bulky substituents at imide positions reveals significantly higher solid-state fluorescence quantum yields of the 1,7-substituted PBIs.
• Consecutive Charging of a Perylene Bisimide Dye by Multistep Low-Energy Solar-Light-Induced Electron Transfer Towards H 2 Evolution. Xu, Yucheng; Zheng, Jiaxin; Lindner, Joachim O.; Wen, Xinbo; Jiang, Nianqiang; Hu, Zhicheng; Liu, Linlin; Huang, Fei; Würthner, Frank; Xie, Zengqi. In Angew. Chem. Int. Ed., 59(26), pp. 10363–10367. 2020.
  • [ Abstract ]
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  A photocatalytic system containing a perylene bisimide (PBI) dye as a photosensitizer anchored to titanium dioxide (TiO2) nanoparticles through carboxyl groups was constructed. Under solar‐light irradiation in the presence of sacrificial triethanolamine (TEOA) in neutral and basic conditions (pH 8.5), a reaction cascade is initiated in which the PBI molecule first absorbs green light, giving the formation of a stable radical anion (PBI.−), which in a second step absorbs near‐infrared light, forming a stable PBI dianion (PBI2−). Finally, the dianion absorbs red light and injects an electron into the TiO2 nanoparticle that is coated with platinum co‐catalyst for hydrogen evolution. The hydrogen evolution rates (HERs) are as high as 1216 and 1022 μmol h−1 g−1 with simulated sunlight irradiation in neutral and basic conditions, respectively.

  @article{Xu_2020, abstract = {A photocatalytic system containing a perylene bisimide (PBI) dye as a photosensitizer anchored to titanium dioxide (TiO2) nanoparticles through carboxyl groups was constructed. Under solar‐light irradiation in the presence of sacrificial triethanolamine (TEOA) in neutral and basic conditions (pH 8.5), a reaction cascade is initiated in which the PBI molecule first absorbs green light, giving the formation of a stable radical anion (PBI.−), which in a second step absorbs near‐infrared light, forming a stable PBI dianion (PBI2−). Finally, the dianion absorbs red light and injects an electron into the TiO2 nanoparticle that is coated with platinum co‐catalyst for hydrogen evolution. The hydrogen evolution rates (HERs) are as high as 1216 and 1022 μmol h−1 g−1 with simulated sunlight irradiation in neutral and basic conditions, respectively.}, author = {Xu, Yucheng and Zheng, Jiaxin and Lindner, Joachim O. and Wen, Xinbo and Jiang, Nianqiang and Hu, Zhicheng and Liu, Linlin and Huang, Fei and Würthner, Frank and Xie, Zengqi}, journal = {Angew. Chem. Int. Ed.}, keywords = {myown}, month = {04}, number = 26, pages = {10363–10367}, publisher = {Wiley}, title = {Consecutive Charging of a Perylene Bisimide Dye by Multistep Low-Energy Solar-Light-Induced Electron Transfer Towards H 2 Evolution}, volume = 59, year = 2020 }

  %0 Journal Article %1 Xu_2020 %A Xu, Yucheng %A Zheng, Jiaxin %A Lindner, Joachim O. %A Wen, Xinbo %A Jiang, Nianqiang %A Hu, Zhicheng %A Liu, Linlin %A Huang, Fei %A Würthner, Frank %A Xie, Zengqi %D 2020 %I Wiley %J Angew. Chem. Int. Ed. %N 26 %P 10363--10367 %R 10.1002/anie.202001231 %T Consecutive Charging of a Perylene Bisimide Dye by Multistep Low-Energy Solar-Light-Induced Electron Transfer Towards H 2 Evolution %U https://doi.org/10.1002%2Fanie.202001231 %V 59 %X A photocatalytic system containing a perylene bisimide (PBI) dye as a photosensitizer anchored to titanium dioxide (TiO2) nanoparticles through carboxyl groups was constructed. Under solar‐light irradiation in the presence of sacrificial triethanolamine (TEOA) in neutral and basic conditions (pH 8.5), a reaction cascade is initiated in which the PBI molecule first absorbs green light, giving the formation of a stable radical anion (PBI.−), which in a second step absorbs near‐infrared light, forming a stable PBI dianion (PBI2−). Finally, the dianion absorbs red light and injects an electron into the TiO2 nanoparticle that is coated with platinum co‐catalyst for hydrogen evolution. The hydrogen evolution rates (HERs) are as high as 1216 and 1022 μmol h−1 g−1 with simulated sunlight irradiation in neutral and basic conditions, respectively.
• Self-Sorting Supramolecular Polymerization: Helical and Lamellar Aggregates of Tetra-Bay-Acyloxy Perylene Bisimide. Hecht, Markus; Leowanawat, Pawaret; Gerlach, Tabea; Stepanenko, Vladimir; Stolte, Matthias; Lehmann, Matthias; Würthner, Frank. In Angew. Chem. Int. Ed., 59(39), pp. 17084–17090. 2020.
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  A new perylene bisimide (PBI), with a fluorescence quantum yield up to unity, self‐assembles into two polymorphic supramolecular polymers. This PBI bears four solubilizing acyloxy substituents at the bay positions and is unsubstituted at the imide position, thereby allowing hydrogen‐bond‐directed self‐assembly in nonpolar solvents. The formation of the polymorphs is controlled by the cooling rate of hot monomer solutions. They show distinctive absorption profiles and morphologies and can be isolated in different polymorphic liquid‐crystalline states. The interchromophoric arrangement causing the spectral features was elucidated, revealing the formation of columnar and lamellar phases, which are formed by either homo‐ or heterochiral self‐assembly, respectively, of the atropoenantiomeric PBIs. Kinetic studies reveal a narcissistic self‐sorting process upon fast cooling, and that the transformation into the heterochiral (racemic) sheetlike self‐assemblies proceeds by dissociation via the monomeric state.

  @article{Hecht_2020, abstract = {A new perylene bisimide (PBI), with a fluorescence quantum yield up to unity, self‐assembles into two polymorphic supramolecular polymers. This PBI bears four solubilizing acyloxy substituents at the bay positions and is unsubstituted at the imide position, thereby allowing hydrogen‐bond‐directed self‐assembly in nonpolar solvents. The formation of the polymorphs is controlled by the cooling rate of hot monomer solutions. They show distinctive absorption profiles and morphologies and can be isolated in different polymorphic liquid‐crystalline states. The interchromophoric arrangement causing the spectral features was elucidated, revealing the formation of columnar and lamellar phases, which are formed by either homo‐ or heterochiral self‐assembly, respectively, of the atropoenantiomeric PBIs. Kinetic studies reveal a narcissistic self‐sorting process upon fast cooling, and that the transformation into the heterochiral (racemic) sheetlike self‐assemblies proceeds by dissociation via the monomeric state.}, author = {Hecht, Markus and Leowanawat, Pawaret and Gerlach, Tabea and Stepanenko, Vladimir and Stolte, Matthias and Lehmann, Matthias and Würthner, Frank}, journal = {Angew. Chem. Int. Ed.}, keywords = {myown}, month = {08}, number = 39, pages = {17084-17090}, publisher = {Wiley}, title = {Self-Sorting Supramolecular Polymerization: Helical and Lamellar Aggregates of Tetra-Bay-Acyloxy Perylene Bisimide}, volume = 59, year = 2020 }

  %0 Journal Article %1 Hecht_2020 %A Hecht, Markus %A Leowanawat, Pawaret %A Gerlach, Tabea %A Stepanenko, Vladimir %A Stolte, Matthias %A Lehmann, Matthias %A Würthner, Frank %D 2020 %I Wiley %J Angew. Chem. Int. Ed. %N 39 %P 17084-17090 %R 10.1002/anie.202006744 %T Self-Sorting Supramolecular Polymerization: Helical and Lamellar Aggregates of Tetra-Bay-Acyloxy Perylene Bisimide %U https://doi.org/10.1002%2Fanie.202006744 %V 59 %X A new perylene bisimide (PBI), with a fluorescence quantum yield up to unity, self‐assembles into two polymorphic supramolecular polymers. This PBI bears four solubilizing acyloxy substituents at the bay positions and is unsubstituted at the imide position, thereby allowing hydrogen‐bond‐directed self‐assembly in nonpolar solvents. The formation of the polymorphs is controlled by the cooling rate of hot monomer solutions. They show distinctive absorption profiles and morphologies and can be isolated in different polymorphic liquid‐crystalline states. The interchromophoric arrangement causing the spectral features was elucidated, revealing the formation of columnar and lamellar phases, which are formed by either homo‐ or heterochiral self‐assembly, respectively, of the atropoenantiomeric PBIs. Kinetic studies reveal a narcissistic self‐sorting process upon fast cooling, and that the transformation into the heterochiral (racemic) sheetlike self‐assemblies proceeds by dissociation via the monomeric state.
• Anion-Coordination-Assisted Assembly of Supramolecular Charge-Transfer Complexes Based on Tris(urea) Ligands. Zhang, Dan; Hou, Le-Kai; Zhang, Qiang; He, Jia-Wei; Feng, Hong-Jian; Würthner, Frank; Yang, Xiao-Juan; Wu, Biao. In Chem. Eur. J., 26(6), pp. 1414–1421. 2020.
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  Charge‐transfer (CT) complexes, formed by noncovalent bonding between electron‐rich (donor, D) and electron‐deficient (acceptor, A) molecules (or moieties) have attracted considerable attention due to their fascinating structures and potential applications. Herein, we demonstrate that anion coordination is a promising strategy to promote CT complex formation between anion‐binding, electron‐rich tris(urea) donor ligands (D) and electron‐deficient viologen cation acceptors (A), which form co‐crystals featuring infinite ⋅⋅⋅DADA⋅⋅⋅ or discrete (circular DADA or three‐decker DAD) π‐stacking interactions. These CT complexes were studied by X‐ray diffraction, UV/Vis spectroscopy, electric conductivity measurements, charge displacement curve (CDC) calculations, and DFT computations.

  @article{Zhang_2020, abstract = {Charge‐transfer (CT) complexes, formed by noncovalent bonding between electron‐rich (donor, D) and electron‐deficient (acceptor, A) molecules (or moieties) have attracted considerable attention due to their fascinating structures and potential applications. Herein, we demonstrate that anion coordination is a promising strategy to promote CT complex formation between anion‐binding, electron‐rich tris(urea) donor ligands (D) and electron‐deficient viologen cation acceptors (A), which form co‐crystals featuring infinite ⋅⋅⋅DADA⋅⋅⋅ or discrete (circular DADA or three‐decker DAD) π‐stacking interactions. These CT complexes were studied by X‐ray diffraction, UV/Vis spectroscopy, electric conductivity measurements, charge displacement curve (CDC) calculations, and DFT computations.}, author = {Zhang, Dan and Hou, Le-Kai and Zhang, Qiang and He, Jia-Wei and Feng, Hong-Jian and Würthner, Frank and Yang, Xiao-Juan and Wu, Biao}, journal = {Chem. Eur. J.}, keywords = {myown}, month = {01}, number = 6, pages = {1414–1421}, publisher = {Wiley}, title = {Anion-Coordination-Assisted Assembly of Supramolecular Charge-Transfer Complexes Based on Tris(urea) Ligands}, volume = 26, year = 2020 }

  %0 Journal Article %1 Zhang_2020 %A Zhang, Dan %A Hou, Le-Kai %A Zhang, Qiang %A He, Jia-Wei %A Feng, Hong-Jian %A Würthner, Frank %A Yang, Xiao-Juan %A Wu, Biao %D 2020 %I Wiley %J Chem. Eur. J. %N 6 %P 1414--1421 %R 10.1002/chem.201905021 %T Anion-Coordination-Assisted Assembly of Supramolecular Charge-Transfer Complexes Based on Tris(urea) Ligands %U https://doi.org/10.1002%2Fchem.201905021 %V 26 %X Charge‐transfer (CT) complexes, formed by noncovalent bonding between electron‐rich (donor, D) and electron‐deficient (acceptor, A) molecules (or moieties) have attracted considerable attention due to their fascinating structures and potential applications. Herein, we demonstrate that anion coordination is a promising strategy to promote CT complex formation between anion‐binding, electron‐rich tris(urea) donor ligands (D) and electron‐deficient viologen cation acceptors (A), which form co‐crystals featuring infinite ⋅⋅⋅DADA⋅⋅⋅ or discrete (circular DADA or three‐decker DAD) π‐stacking interactions. These CT complexes were studied by X‐ray diffraction, UV/Vis spectroscopy, electric conductivity measurements, charge displacement curve (CDC) calculations, and DFT computations.
• On the photophysical properties of IrIII, PtII, and PdII (phenylpyrazole) (phenyldipyrrin) complexes. Föller, Jelena; Friese, Daniel H.; Riese, Stefan; Kaminski, Jeremy M.; Metz, Simon; Schmidt, David; Würthner, Frank; Lambert, Christoph; Marian, Christel M. In Phys. Chem. Chem. Phys., 22(6), pp. 3217–3233. 2020.
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  The absorption and emission characteristics of (ppz)2(dipy)IrIII, (ppz)(dipy)PtII and (ppz)(dipy)PdII, where ppz stands for phenylpyrazole and dipy for a phenyl meso-substituted dipyrrin ligand, have been investigated by means of combined density functional theory and multireference configuration interaction including scalar relativistic and spin–orbit coupling effects. These results were compared with experimental spectra. The complexes exhibit a high density of low-lying electronically excited states originating from ligand-centered (LC) and metal-to-ligand charge transfer (MLCT) states involving the dipyrrin ligand. In addition, metal-centered (MC) states are found to be low-lying in the Pd complex. In all three cases, the first strong absorption band and the phosphorescence emission band stem from LC excitations on the dipyrrin ligand with small MLCT contributions. The MLCT states show more pronounced relaxation effects than the LC states, with the consequence that the first excited state with predominant singlet multiplicity is of SMLCT/LC type in the heavier Ir and Pt complexes. Substantial spin–orbit coupling between SMLCT/LC and TLC enables fast and efficient intersystem crossing (ISC) and a high triplet quantum yield. Phosphorescence rate constants are rather small in accord with the dominant LC character of the transitions. Out-of-plane distortion promotes nonradiative decay of the excited state population via the MC states thus explaining the lower phosphorescence quantum yield of the Pt complex. The spectral properties of the Pd complex are different in many aspects. Optimization of the S1 state yields a dipyrrin intraligand charge transfer (ILCT) state with highly distorted nuclear arrangement in the butterfly conformers leading to nonradiative deactivation. In contrast, the primarily excited SLC state and the SMLCT/LC state of the twist conformer have nearly equal adiabatic excitation energies. The lack of a driving force toward the SMLCT/LC minimum, the high fluorescence rate constant of the bright SLC state and its moderately efficient ISC to the triplet manifold explain the experimentally observed dual emission of the Pd complex at room temperature.

  @article{C9CP05603C, abstract = {The absorption and emission characteristics of (ppz)2(dipy)IrIII, (ppz)(dipy)PtII and (ppz)(dipy)PdII, where ppz stands for phenylpyrazole and dipy for a phenyl meso-substituted dipyrrin ligand, have been investigated by means of combined density functional theory and multireference configuration interaction including scalar relativistic and spin–orbit coupling effects. These results were compared with experimental spectra. The complexes exhibit a high density of low-lying electronically excited states originating from ligand-centered (LC) and metal-to-ligand charge transfer (MLCT) states involving the dipyrrin ligand. In addition, metal-centered (MC) states are found to be low-lying in the Pd complex. In all three cases, the first strong absorption band and the phosphorescence emission band stem from LC excitations on the dipyrrin ligand with small MLCT contributions. The MLCT states show more pronounced relaxation effects than the LC states, with the consequence that the first excited state with predominant singlet multiplicity is of SMLCT/LC type in the heavier Ir and Pt complexes. Substantial spin–orbit coupling between SMLCT/LC and TLC enables fast and efficient intersystem crossing (ISC) and a high triplet quantum yield. Phosphorescence rate constants are rather small in accord with the dominant LC character of the transitions. Out-of-plane distortion promotes nonradiative decay of the excited state population via the MC states thus explaining the lower phosphorescence quantum yield of the Pt complex. The spectral properties of the Pd complex are different in many aspects. Optimization of the S1 state yields a dipyrrin intraligand charge transfer (ILCT) state with highly distorted nuclear arrangement in the butterfly conformers leading to nonradiative deactivation. In contrast, the primarily excited SLC state and the SMLCT/LC state of the twist conformer have nearly equal adiabatic excitation energies. The lack of a driving force toward the SMLCT/LC minimum, the high fluorescence rate constant of the bright SLC state and its moderately efficient ISC to the triplet manifold explain the experimentally observed dual emission of the Pd complex at room temperature.}, author = {Föller, Jelena and Friese, Daniel H. and Riese, Stefan and Kaminski, Jeremy M. and Metz, Simon and Schmidt, David and Würthner, Frank and Lambert, Christoph and Marian, Christel M.}, journal = {Phys. Chem. Chem. Phys.}, keywords = {myown}, number = 6, pages = {3217-3233}, publisher = {The Royal Society of Chemistry}, title = {On the photophysical properties of IrIII, PtII, and PdII (phenylpyrazole) (phenyldipyrrin) complexes}, volume = 22, year = 2020 }

  %0 Journal Article %1 C9CP05603C %A Föller, Jelena %A Friese, Daniel H. %A Riese, Stefan %A Kaminski, Jeremy M. %A Metz, Simon %A Schmidt, David %A Würthner, Frank %A Lambert, Christoph %A Marian, Christel M. %D 2020 %I The Royal Society of Chemistry %J Phys. Chem. Chem. Phys. %N 6 %P 3217-3233 %R 10.1039/C9CP05603C %T On the photophysical properties of IrIII, PtII, and PdII (phenylpyrazole) (phenyldipyrrin) complexes %U http://dx.doi.org/10.1039/C9CP05603C %V 22 %X The absorption and emission characteristics of (ppz)2(dipy)IrIII, (ppz)(dipy)PtII and (ppz)(dipy)PdII, where ppz stands for phenylpyrazole and dipy for a phenyl meso-substituted dipyrrin ligand, have been investigated by means of combined density functional theory and multireference configuration interaction including scalar relativistic and spin–orbit coupling effects. These results were compared with experimental spectra. The complexes exhibit a high density of low-lying electronically excited states originating from ligand-centered (LC) and metal-to-ligand charge transfer (MLCT) states involving the dipyrrin ligand. In addition, metal-centered (MC) states are found to be low-lying in the Pd complex. In all three cases, the first strong absorption band and the phosphorescence emission band stem from LC excitations on the dipyrrin ligand with small MLCT contributions. The MLCT states show more pronounced relaxation effects than the LC states, with the consequence that the first excited state with predominant singlet multiplicity is of SMLCT/LC type in the heavier Ir and Pt complexes. Substantial spin–orbit coupling between SMLCT/LC and TLC enables fast and efficient intersystem crossing (ISC) and a high triplet quantum yield. Phosphorescence rate constants are rather small in accord with the dominant LC character of the transitions. Out-of-plane distortion promotes nonradiative decay of the excited state population via the MC states thus explaining the lower phosphorescence quantum yield of the Pt complex. The spectral properties of the Pd complex are different in many aspects. Optimization of the S1 state yields a dipyrrin intraligand charge transfer (ILCT) state with highly distorted nuclear arrangement in the butterfly conformers leading to nonradiative deactivation. In contrast, the primarily excited SLC state and the SMLCT/LC state of the twist conformer have nearly equal adiabatic excitation energies. The lack of a driving force toward the SMLCT/LC minimum, the high fluorescence rate constant of the bright SLC state and its moderately efficient ISC to the triplet manifold explain the experimentally observed dual emission of the Pd complex at room temperature.
• Unfolding multi-stranded perylene bisimide LC columns – a mesogen design for efficient nanoscale multilayer self-assembly. Lehmann, Matthias; Hecht, Markus; Herbst, Stefanie; Cui, Kang; Würthner, Frank. In Chem. Commun., 56(90), pp. 14015–14018. 2020.
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  A mesogen tethered, twofold bay-substituted perylene bisimide (PBI) is found to generate a columnar phase, which unfolds and gradually transforms to a completely nanosegregated multilayer columnar–lamellar liquid crystal. The structure is based on the formation of bundles of H-bonded PBI strands in the central layer. This design opens the way to new complex multifunctional materials.

  @article{D0CC06458K, abstract = {A mesogen tethered{,} twofold bay-substituted perylene bisimide (PBI) is found to generate a columnar phase{,} which unfolds and gradually transforms to a completely nanosegregated multilayer columnar–lamellar liquid crystal. The structure is based on the formation of bundles of H-bonded PBI strands in the central layer. This design opens the way to new complex multifunctional materials.}, author = {Lehmann, Matthias and Hecht, Markus and Herbst, Stefanie and Cui, Kang and Würthner, Frank}, journal = {Chem. Commun.}, keywords = {myown}, number = 90, pages = {14015-14018}, publisher = {The Royal Society of Chemistry}, title = {Unfolding multi-stranded perylene bisimide LC columns – a mesogen design for efficient nanoscale multilayer self-assembly}, volume = 56, year = 2020 }

  %0 Journal Article %1 D0CC06458K %A Lehmann, Matthias %A Hecht, Markus %A Herbst, Stefanie %A Cui, Kang %A Würthner, Frank %D 2020 %I The Royal Society of Chemistry %J Chem. Commun. %N 90 %P 14015-14018 %R 10.1039/D0CC06458K %T Unfolding multi-stranded perylene bisimide LC columns – a mesogen design for efficient nanoscale multilayer self-assembly %U http://dx.doi.org/10.1039/D0CC06458K %V 56 %X A mesogen tethered, twofold bay-substituted perylene bisimide (PBI) is found to generate a columnar phase, which unfolds and gradually transforms to a completely nanosegregated multilayer columnar–lamellar liquid crystal. The structure is based on the formation of bundles of H-bonded PBI strands in the central layer. This design opens the way to new complex multifunctional materials.
• [n]Helicene Diimides (n = 5, 6, and 7): Through-Bond versus Through-Space Conjugation. Saal, Fridolin; Zhang, Fangyuan; Holzapfel, Marco; Stolte, Matthias; Michail, Evripidis; Moos, Michael; Schmiedel, Alexander; Krause, Ana-Maria; Lambert, Christoph; Würthner, Frank; Ravat, Prince. In J. Am. Chem. Soc., 142(51), pp. 21298–21303. 2020.
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  The interactions between auxochromic groups in π-conjugated functional molecules dictate their electronic properties. From the standpoint of potential applications, understanding and control of such interactions is a vital requirement for the material design. In this communication, we describe the design, synthesis, and functional properties of a novel class of helically chiral diimide molecules, namely, [n]HDI-OMe (n = 5, 6, and 7), in which two imide units are connected via an [n]helicene skeleton. The experimental results supported by quantum chemical calculations reveal that the helical backbone in these molecules offers not only through-bond but also through-space conjugation between imide groups, which leads to distinct optical and electrochemical properties when compared to the related [n]helicenes and rylene diimides.

  @article{noauthororeditor2020nhelicene, abstract = {The interactions between auxochromic groups in π-conjugated functional molecules dictate their electronic properties. From the standpoint of potential applications, understanding and control of such interactions is a vital requirement for the material design. In this communication, we describe the design, synthesis, and functional properties of a novel class of helically chiral diimide molecules, namely, [n]HDI-OMe (n = 5, 6, and 7), in which two imide units are connected via an [n]helicene skeleton. The experimental results supported by quantum chemical calculations reveal that the helical backbone in these molecules offers not only through-bond but also through-space conjugation between imide groups, which leads to distinct optical and electrochemical properties when compared to the related [n]helicenes and rylene diimides.}, author = {Saal, Fridolin and Zhang, Fangyuan and Holzapfel, Marco and Stolte, Matthias and Michail, Evripidis and Moos, Michael and Schmiedel, Alexander and Krause, Ana-Maria and Lambert, Christoph and Würthner, Frank and Ravat, Prince}, journal = {J. Am. Chem. Soc.}, keywords = {myown}, month = 12, number = 51, pages = {21298-21303}, title = {[n]Helicene Diimides (n = 5, 6, and 7): Through-Bond versus Through-Space Conjugation}, volume = 142, year = 2020 }

  %0 Journal Article %1 noauthororeditor2020nhelicene %A Saal, Fridolin %A Zhang, Fangyuan %A Holzapfel, Marco %A Stolte, Matthias %A Michail, Evripidis %A Moos, Michael %A Schmiedel, Alexander %A Krause, Ana-Maria %A Lambert, Christoph %A Würthner, Frank %A Ravat, Prince %D 2020 %J J. Am. Chem. Soc. %N 51 %P 21298-21303 %R 10.1021/jacs.0c11053 %T [n]Helicene Diimides (n = 5, 6, and 7): Through-Bond versus Through-Space Conjugation %U https://pubs.acs.org/doi/10.1021/jacs.0c11053 %V 142 %X The interactions between auxochromic groups in π-conjugated functional molecules dictate their electronic properties. From the standpoint of potential applications, understanding and control of such interactions is a vital requirement for the material design. In this communication, we describe the design, synthesis, and functional properties of a novel class of helically chiral diimide molecules, namely, [n]HDI-OMe (n = 5, 6, and 7), in which two imide units are connected via an [n]helicene skeleton. The experimental results supported by quantum chemical calculations reveal that the helical backbone in these molecules offers not only through-bond but also through-space conjugation between imide groups, which leads to distinct optical and electrochemical properties when compared to the related [n]helicenes and rylene diimides.
• Quinoidal dicyanomethylene-endcapped cyclopentadithiophenes as vacuum-processable n-type semiconductors. Menekse, Kaan; Chen, Pengzhong; Mahlmeister, Bernhard; Anhalt, Olga; Kudzus, Astrid; Stolte, Matthias; Würthner, Frank. In J. Mater. Chem. C, 8(43), pp. 15303–15311. 2020.
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  Current research in the field of organic photovoltaics is mainly focusing on the application of non-fullerene acceptors in solution-processed materials. Another promising area for their commercial application is all-vacuum-processed organic solar cells enabling not only the formation of homogenous thin films but also the construction of very complex multi-layered architectures. In this field fullerenes C60 and C70 still play the major role as acceptor materials, while alternatives with better optical features still remain rarely reported. One fascinating class of materials is quinoids, due to their interesting energetic properties, which enable not only n-type charge transport but also strong absorption in the visible spectral region even for low molecular weight molecules. Here, we report the synthesis of a series of new vacuum-processable organic pigments based on dicyanomethylene-endcapped cyclopentadithiophenes. This new class of materials is characterized by a high tinctorial strength and a low-lying LUMO level enabling n-type charge transport with mobilities of up to 10−2 cm2 V−1 s−1. Crystal engineering was performed by introducing different residues at the cyclopentadithiophene, which tunes the solid-state molecular packing and thin-film formation. Supramolecular interactions are the dominating structural forces, which help in explaining the OTFT performance along with the film morphologies. As a proof of principle, a power conversion efficiency of up to 0.62% was observed in a fully vacuum-processed planar heterojunction device architecture combining our new quinoidal non-fullerene acceptors with a merocyanine dye as the donor material.

  @article{D0TC02988B, abstract = {Current research in the field of organic photovoltaics is mainly focusing on the application of non-fullerene acceptors in solution-processed materials. Another promising area for their commercial application is all-vacuum-processed organic solar cells enabling not only the formation of homogenous thin films but also the construction of very complex multi-layered architectures. In this field fullerenes C60 and C70 still play the major role as acceptor materials{,} while alternatives with better optical features still remain rarely reported. One fascinating class of materials is quinoids{,} due to their interesting energetic properties{,} which enable not only n-type charge transport but also strong absorption in the visible spectral region even for low molecular weight molecules. Here{,} we report the synthesis of a series of new vacuum-processable organic pigments based on dicyanomethylene-endcapped cyclopentadithiophenes. This new class of materials is characterized by a high tinctorial strength and a low-lying LUMO level enabling n-type charge transport with mobilities of up to 10−2 cm2 V−1 s−1. Crystal engineering was performed by introducing different residues at the cyclopentadithiophene{,} which tunes the solid-state molecular packing and thin-film formation. Supramolecular interactions are the dominating structural forces{,} which help in explaining the OTFT performance along with the film morphologies. As a proof of principle{,} a power conversion efficiency of up to 0.62% was observed in a fully vacuum-processed planar heterojunction device architecture combining our new quinoidal non-fullerene acceptors with a merocyanine dye as the donor material.}, author = {Menekse, Kaan and Chen, Pengzhong and Mahlmeister, Bernhard and Anhalt, Olga and Kudzus, Astrid and Stolte, Matthias and Würthner, Frank}, journal = {J. Mater. Chem. C}, keywords = {myown}, number = 43, pages = {15303-15311}, publisher = {The Royal Society of Chemistry}, title = {Quinoidal dicyanomethylene-endcapped cyclopentadithiophenes as vacuum-processable n-type semiconductors}, volume = 8, year = 2020 }

  %0 Journal Article %1 D0TC02988B %A Menekse, Kaan %A Chen, Pengzhong %A Mahlmeister, Bernhard %A Anhalt, Olga %A Kudzus, Astrid %A Stolte, Matthias %A Würthner, Frank %D 2020 %I The Royal Society of Chemistry %J J. Mater. Chem. C %N 43 %P 15303-15311 %R 10.1039/D0TC02988B %T Quinoidal dicyanomethylene-endcapped cyclopentadithiophenes as vacuum-processable n-type semiconductors %U http://dx.doi.org/10.1039/D0TC02988B %V 8 %X Current research in the field of organic photovoltaics is mainly focusing on the application of non-fullerene acceptors in solution-processed materials. Another promising area for their commercial application is all-vacuum-processed organic solar cells enabling not only the formation of homogenous thin films but also the construction of very complex multi-layered architectures. In this field fullerenes C60 and C70 still play the major role as acceptor materials, while alternatives with better optical features still remain rarely reported. One fascinating class of materials is quinoids, due to their interesting energetic properties, which enable not only n-type charge transport but also strong absorption in the visible spectral region even for low molecular weight molecules. Here, we report the synthesis of a series of new vacuum-processable organic pigments based on dicyanomethylene-endcapped cyclopentadithiophenes. This new class of materials is characterized by a high tinctorial strength and a low-lying LUMO level enabling n-type charge transport with mobilities of up to 10−2 cm2 V−1 s−1. Crystal engineering was performed by introducing different residues at the cyclopentadithiophene, which tunes the solid-state molecular packing and thin-film formation. Supramolecular interactions are the dominating structural forces, which help in explaining the OTFT performance along with the film morphologies. As a proof of principle, a power conversion efficiency of up to 0.62% was observed in a fully vacuum-processed planar heterojunction device architecture combining our new quinoidal non-fullerene acceptors with a merocyanine dye as the donor material.
• Efficient Electronic Coupling in Perylenediimide Multilayered Films on Indium Tin Oxide. Silva, Barbara P. G.; Tosco, Bruna; de Florio, Daniel Z.; Stepanenko, Vladimir; Würthner, Frank; Rey, José Fernando Q.; Brochsztain, Sergio. In J. Phys. Chem. C., 124(10), pp. 5541–5551. 2020.
  • [ Abstract ]
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  Layer-by-layer thin films with up to 11 layers of N,N′-bis(2-phosphonoethyl)-3,4,9,10-perylenediimide (PPDI) were deposited on indium tin oxide (ITO) substrates by the zirconium phosphonate method. Film growth was studied by UV–visible absorption spectroscopy, X-ray photoelectron spectroscopy (XPS), X-ray reflectivity (XRR), and atomic force microscopy (AFM). It was found that the films grow in a linear fashion, with the same amount of dye incorporated in each deposition cycle, and the dye molecules were π-stacked within the films. For a 10-layer film, film thickness was estimated as 20 nm, giving 2 nm per layer. Electrochemical characterization of the films was performed using cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). CV measurements showed that peak currents were proportional to the number of layers, for both the first and second reductions of PPDI. The effect of applied bias on the EIS response was studied in both the impedance (Bode plots) and capacitance (Cole–Cole plots) complex planes. The width of the semicircles in the Cole–Cole plots was proportional to the number of layers when the electrode was biased at −0.6 V, which is within the redox window for PPDI reduction. The pseudocapacitance of the films was obtained from the width of the semicircles, allowing the calculation of electroactive surface coverages and electron-transfer rates. Surface coverages of ca. 1 × 10–10 mol/cm2 per layer were obtained, whereas electron transfer rates decreased with film thickness, from 41 s–1 in a monolayer to 1.3 s–1 in a 10-layer film. The present study shows that compact PPDI films were formed, with efficient electronic coupling between the PPDI units, rendering the films attractive as electron transport layers for organic electronics.

  @article{Silva_2020, abstract = {Layer-by-layer thin films with up to 11 layers of N,N′-bis(2-phosphonoethyl)-3,4,9,10-perylenediimide (PPDI) were deposited on indium tin oxide (ITO) substrates by the zirconium phosphonate method. Film growth was studied by UV–visible absorption spectroscopy, X-ray photoelectron spectroscopy (XPS), X-ray reflectivity (XRR), and atomic force microscopy (AFM). It was found that the films grow in a linear fashion, with the same amount of dye incorporated in each deposition cycle, and the dye molecules were π-stacked within the films. For a 10-layer film, film thickness was estimated as 20 nm, giving 2 nm per layer. Electrochemical characterization of the films was performed using cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). CV measurements showed that peak currents were proportional to the number of layers, for both the first and second reductions of PPDI. The effect of applied bias on the EIS response was studied in both the impedance (Bode plots) and capacitance (Cole–Cole plots) complex planes. The width of the semicircles in the Cole–Cole plots was proportional to the number of layers when the electrode was biased at −0.6 V, which is within the redox window for PPDI reduction. The pseudocapacitance of the films was obtained from the width of the semicircles, allowing the calculation of electroactive surface coverages and electron-transfer rates. Surface coverages of ca. 1 × 10–10 mol/cm2 per layer were obtained, whereas electron transfer rates decreased with film thickness, from 41 s–1 in a monolayer to 1.3 s–1 in a 10-layer film. The present study shows that compact PPDI films were formed, with efficient electronic coupling between the PPDI units, rendering the films attractive as electron transport layers for organic electronics.}, author = {Silva, Barbara P. G. and Tosco, Bruna and de Florio, Daniel Z. and Stepanenko, Vladimir and Würthner, Frank and Rey, José Fernando Q. and Brochsztain, Sergio}, journal = {J. Phys. Chem. C.}, keywords = {myown}, month = {02}, number = 10, pages = {5541–5551}, publisher = {American Chemical Society (ACS)}, title = {Efficient Electronic Coupling in Perylenediimide Multilayered Films on Indium Tin Oxide}, volume = 124, year = 2020 }

  %0 Journal Article %1 Silva_2020 %A Silva, Barbara P. G. %A Tosco, Bruna %A de Florio, Daniel Z. %A Stepanenko, Vladimir %A Würthner, Frank %A Rey, José Fernando Q. %A Brochsztain, Sergio %D 2020 %I American Chemical Society (ACS) %J J. Phys. Chem. C. %N 10 %P 5541--5551 %R 10.1021/acs.jpcc.9b11373 %T Efficient Electronic Coupling in Perylenediimide Multilayered Films on Indium Tin Oxide %U https://doi.org/10.1021%2Facs.jpcc.9b11373 %V 124 %X Layer-by-layer thin films with up to 11 layers of N,N′-bis(2-phosphonoethyl)-3,4,9,10-perylenediimide (PPDI) were deposited on indium tin oxide (ITO) substrates by the zirconium phosphonate method. Film growth was studied by UV–visible absorption spectroscopy, X-ray photoelectron spectroscopy (XPS), X-ray reflectivity (XRR), and atomic force microscopy (AFM). It was found that the films grow in a linear fashion, with the same amount of dye incorporated in each deposition cycle, and the dye molecules were π-stacked within the films. For a 10-layer film, film thickness was estimated as 20 nm, giving 2 nm per layer. Electrochemical characterization of the films was performed using cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). CV measurements showed that peak currents were proportional to the number of layers, for both the first and second reductions of PPDI. The effect of applied bias on the EIS response was studied in both the impedance (Bode plots) and capacitance (Cole–Cole plots) complex planes. The width of the semicircles in the Cole–Cole plots was proportional to the number of layers when the electrode was biased at −0.6 V, which is within the redox window for PPDI reduction. The pseudocapacitance of the films was obtained from the width of the semicircles, allowing the calculation of electroactive surface coverages and electron-transfer rates. Surface coverages of ca. 1 × 10–10 mol/cm2 per layer were obtained, whereas electron transfer rates decreased with film thickness, from 41 s–1 in a monolayer to 1.3 s–1 in a 10-layer film. The present study shows that compact PPDI films were formed, with efficient electronic coupling between the PPDI units, rendering the films attractive as electron transport layers for organic electronics.
• Tracking Structural Evolution during Symmetry-Breaking Charge Separation in Quadrupolar Perylene Bisimide with Time-Resolved Impulsive Stimulated Raman Spectroscopy. Kim, Woojae; Kim, Taeyeon; Kang, Seongsoo; Hong, Yongseok; Würthner, Frank; Kim, Dongho. In Angew. Chem. Int. Ed., 59(22), pp. 8571–8578. 2020.
  • [ Abstract ]
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  Elucidating structural roles in photoinduced charge transfer is indispensable, as nuclear rearrangements are simultaneously usually involved in the dynamics. However, it is hard to evaluate whether the structural changes occur or not by using conventional time‐resolved electronic spectroscopy. Here, time‐resolved impulsive stimulated Raman spectroscopy is applied to record the evolution of vibrational snapshots during charge‐separation dynamics of donor–acceptor–donor‐type quadrupolar perylene bisimide in real time. Drastic frequency shifts were observed for several Raman bands with their population kinetics, thus symmetry‐breaking charge separation accompanies significant structural changes, as supported by (TD)‐DFT calculations. A comparison between time‐resolved Raman spectra of the neutral S1 state and the radical anion species shows that the spectral signatures, especially in high‐frequency regions, provide important clues to bond length alternation patterns in the PBI core.

  @article{Kim_2020, abstract = {Elucidating structural roles in photoinduced charge transfer is indispensable, as nuclear rearrangements are simultaneously usually involved in the dynamics. However, it is hard to evaluate whether the structural changes occur or not by using conventional time‐resolved electronic spectroscopy. Here, time‐resolved impulsive stimulated Raman spectroscopy is applied to record the evolution of vibrational snapshots during charge‐separation dynamics of donor–acceptor–donor‐type quadrupolar perylene bisimide in real time. Drastic frequency shifts were observed for several Raman bands with their population kinetics, thus symmetry‐breaking charge separation accompanies significant structural changes, as supported by (TD)‐DFT calculations. A comparison between time‐resolved Raman spectra of the neutral S1 state and the radical anion species shows that the spectral signatures, especially in high‐frequency regions, provide important clues to bond length alternation patterns in the PBI core.}, author = {Kim, Woojae and Kim, Taeyeon and Kang, Seongsoo and Hong, Yongseok and Würthner, Frank and Kim, Dongho}, journal = {Angew. Chem. Int. Ed.}, keywords = {myown}, month = {04}, number = 22, pages = {8571–8578}, publisher = {Wiley}, title = {Tracking Structural Evolution during Symmetry-Breaking Charge Separation in Quadrupolar Perylene Bisimide with Time-Resolved Impulsive Stimulated Raman Spectroscopy}, volume = 59, year = 2020 }

  %0 Journal Article %1 Kim_2020 %A Kim, Woojae %A Kim, Taeyeon %A Kang, Seongsoo %A Hong, Yongseok %A Würthner, Frank %A Kim, Dongho %D 2020 %I Wiley %J Angew. Chem. Int. Ed. %N 22 %P 8571--8578 %R 10.1002/anie.202002733 %T Tracking Structural Evolution during Symmetry-Breaking Charge Separation in Quadrupolar Perylene Bisimide with Time-Resolved Impulsive Stimulated Raman Spectroscopy %U https://doi.org/10.1002%2Fanie.202002733 %V 59 %X Elucidating structural roles in photoinduced charge transfer is indispensable, as nuclear rearrangements are simultaneously usually involved in the dynamics. However, it is hard to evaluate whether the structural changes occur or not by using conventional time‐resolved electronic spectroscopy. Here, time‐resolved impulsive stimulated Raman spectroscopy is applied to record the evolution of vibrational snapshots during charge‐separation dynamics of donor–acceptor–donor‐type quadrupolar perylene bisimide in real time. Drastic frequency shifts were observed for several Raman bands with their population kinetics, thus symmetry‐breaking charge separation accompanies significant structural changes, as supported by (TD)‐DFT calculations. A comparison between time‐resolved Raman spectra of the neutral S1 state and the radical anion species shows that the spectral signatures, especially in high‐frequency regions, provide important clues to bond length alternation patterns in the PBI core.
• Chiroptical Properties of Indolenine Squaraines with a Stereogenic Center at Close Proximity. Selby, Joshua; Holzapfel, Marco; Lombe, Blaise Kimbadi; Schmidt, David; Krause, Ana-Maria; Würthner, Frank; Bringmann, Gerhard; Lambert, Christoph. In J. Org. chem., 85(19), pp. 12227–12242. 2020.
  • [ Abstract ]
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  A series of four indolenine squaraines bearing a chiral center at the 3-position of the indolenine moiety, with either an n-propyl or a phenyl group alongside a methyl group, were synthesized and obtained in a high purity of ≥98% for the desired stereoisomer. The indolenine precursors with a phenyl group attached at the chiral center were asymmetrically synthesized using a pericyclic-reaction cascade and obtained in a high ee of 98%, whereas the ones with an n-propyl group were prepared by kinetic resolution through asymmetric hydrogenation, resulting in an ee of up to 98%. X-ray crystallography revealed a slightly twisted geometry for the phenyl-substituted cisoid squaraine derivative, whereas the n-propyl-substituted derivative possessed the expected planar geometry. Variation of the substitution also influenced the optical properties, where the introduction of phenyl groups caused a progressive red-shift and reduction in squared transition moments, as well as reduced fluorescence quantum yields, Stokes shifts, and fluorescence lifetimes. All of the investigated compounds exhibited strong ECD signals, with Δε values of up to 24 M–1 cm–1 for the HOMO–LUMO transition. DFT calculations indicated that this was due to both large electric and magnetic transition moments, although the two vectors were mutually almost orthogonal.

  @article{Selby_2020, abstract = {A series of four indolenine squaraines bearing a chiral center at the 3-position of the indolenine moiety, with either an n-propyl or a phenyl group alongside a methyl group, were synthesized and obtained in a high purity of ≥98% for the desired stereoisomer. The indolenine precursors with a phenyl group attached at the chiral center were asymmetrically synthesized using a pericyclic-reaction cascade and obtained in a high ee of 98%, whereas the ones with an n-propyl group were prepared by kinetic resolution through asymmetric hydrogenation, resulting in an ee of up to 98%. X-ray crystallography revealed a slightly twisted geometry for the phenyl-substituted cisoid squaraine derivative, whereas the n-propyl-substituted derivative possessed the expected planar geometry. Variation of the substitution also influenced the optical properties, where the introduction of phenyl groups caused a progressive red-shift and reduction in squared transition moments, as well as reduced fluorescence quantum yields, Stokes shifts, and fluorescence lifetimes. All of the investigated compounds exhibited strong ECD signals, with Δε values of up to 24 M–1 cm–1 for the HOMO–LUMO transition. DFT calculations indicated that this was due to both large electric and magnetic transition moments, although the two vectors were mutually almost orthogonal.}, author = {Selby, Joshua and Holzapfel, Marco and Lombe, Blaise Kimbadi and Schmidt, David and Krause, Ana-Maria and Würthner, Frank and Bringmann, Gerhard and Lambert, Christoph}, journal = {J. Org. chem.}, keywords = {myown}, month = {09}, number = 19, pages = {12227–12242}, publisher = {American Chemical Society ({ACS})}, title = {Chiroptical Properties of Indolenine Squaraines with a Stereogenic Center at Close Proximity}, volume = 85, year = 2020 }

  %0 Journal Article %1 Selby_2020 %A Selby, Joshua %A Holzapfel, Marco %A Lombe, Blaise Kimbadi %A Schmidt, David %A Krause, Ana-Maria %A Würthner, Frank %A Bringmann, Gerhard %A Lambert, Christoph %D 2020 %I American Chemical Society (ACS) %J J. Org. chem. %N 19 %P 12227--12242 %R 10.1021/acs.joc.0c01422 %T Chiroptical Properties of Indolenine Squaraines with a Stereogenic Center at Close Proximity %U https://doi.org/10.1021%2Facs.joc.0c01422 %V 85 %X A series of four indolenine squaraines bearing a chiral center at the 3-position of the indolenine moiety, with either an n-propyl or a phenyl group alongside a methyl group, were synthesized and obtained in a high purity of ≥98% for the desired stereoisomer. The indolenine precursors with a phenyl group attached at the chiral center were asymmetrically synthesized using a pericyclic-reaction cascade and obtained in a high ee of 98%, whereas the ones with an n-propyl group were prepared by kinetic resolution through asymmetric hydrogenation, resulting in an ee of up to 98%. X-ray crystallography revealed a slightly twisted geometry for the phenyl-substituted cisoid squaraine derivative, whereas the n-propyl-substituted derivative possessed the expected planar geometry. Variation of the substitution also influenced the optical properties, where the introduction of phenyl groups caused a progressive red-shift and reduction in squared transition moments, as well as reduced fluorescence quantum yields, Stokes shifts, and fluorescence lifetimes. All of the investigated compounds exhibited strong ECD signals, with Δε values of up to 24 M–1 cm–1 for the HOMO–LUMO transition. DFT calculations indicated that this was due to both large electric and magnetic transition moments, although the two vectors were mutually almost orthogonal.
• Modulation of the Self-Assembly of Amphiphiles in Water from Enthalpy- to Entropy-Driven by Enwrapping Substituents. Syamala, Pradeep P. N.; Würthner, Frank. In Chemistry A European Journal, 26(38), pp. 8426–8434. 2020.
  • [ Abstract ]
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  Depending on the connectivity of solubilizing oligoethylene glycol (OEG) side chains to the π‐cores of amphiphilic naphthalene and perylene bisimide dyes, self‐assembly in water occurs either upon heating or cooling. Herein, we show that this effect originates from differences in the enwrapping capability of the π‐cores by the OEG chains. Rylene bisimides bearing phenyl substituents with three OEG chains attached directly to the hydrophobic π‐cores are strongly sequestered by the OEG chains. These molecules self‐assemble at elevated temperatures in an entropy‐driven process according to temperature‐ and concentration‐dependent UV/Vis spectroscopy and calorimetric dilution studies. In contrast, for rylene bisimides in which phenyl substituents with three OEG chains are attached via a methylene spacer, leading to much weaker sequestration, self‐assembly originates upon cooling in an enthalpy‐driven process. Our explanation for this controversial behavior is that the aggregation in the latter case is dictated by the release of “high energy water” from the hydrophobic π‐surfaces as well as dispersion interactions between the π‐scaffolds which drive the self‐assembly in an enthalpically driven process. In contrast, for the former case we suggest that in addition to the conventional explanation of a dehydration of hydrogen‐bonded water molecules from OEG units it is in particular the increase in conformational entropy of back‐folded OEG side chains upon aggregation that provides the pronounced gain in entropy that drives the aggregation process. Thus, our studies revealed that a subtle change in the attachment of solubilizing substituents can switch the thermodynamic signature for the self‐assembly of amphiphilic dyes in water from enthalpy‐ to entropy‐driven.

  @article{Syamala_2020, abstract = {Depending on the connectivity of solubilizing oligoethylene glycol (OEG) side chains to the π‐cores of amphiphilic naphthalene and perylene bisimide dyes, self‐assembly in water occurs either upon heating or cooling. Herein, we show that this effect originates from differences in the enwrapping capability of the π‐cores by the OEG chains. Rylene bisimides bearing phenyl substituents with three OEG chains attached directly to the hydrophobic π‐cores are strongly sequestered by the OEG chains. These molecules self‐assemble at elevated temperatures in an entropy‐driven process according to temperature‐ and concentration‐dependent UV/Vis spectroscopy and calorimetric dilution studies. In contrast, for rylene bisimides in which phenyl substituents with three OEG chains are attached via a methylene spacer, leading to much weaker sequestration, self‐assembly originates upon cooling in an enthalpy‐driven process. Our explanation for this controversial behavior is that the aggregation in the latter case is dictated by the release of “high energy water” from the hydrophobic π‐surfaces as well as dispersion interactions between the π‐scaffolds which drive the self‐assembly in an enthalpically driven process. In contrast, for the former case we suggest that in addition to the conventional explanation of a dehydration of hydrogen‐bonded water molecules from OEG units it is in particular the increase in conformational entropy of back‐folded OEG side chains upon aggregation that provides the pronounced gain in entropy that drives the aggregation process. Thus, our studies revealed that a subtle change in the attachment of solubilizing substituents can switch the thermodynamic signature for the self‐assembly of amphiphilic dyes in water from enthalpy‐ to entropy‐driven.}, author = {Syamala, Pradeep P. N. and Würthner, Frank}, journal = {Chemistry A European Journal}, keywords = {myown}, month = {06}, number = 38, pages = {8426–8434}, publisher = {Wiley}, title = {Modulation of the Self-Assembly of Amphiphiles in Water from Enthalpy- to Entropy-Driven by Enwrapping Substituents}, volume = 26, year = 2020 }

  %0 Journal Article %1 Syamala_2020 %A Syamala, Pradeep P. N. %A Würthner, Frank %D 2020 %I Wiley %J Chemistry A European Journal %N 38 %P 8426--8434 %R 10.1002/chem.202000995 %T Modulation of the Self-Assembly of Amphiphiles in Water from Enthalpy- to Entropy-Driven by Enwrapping Substituents %U https://doi.org/10.1002%2Fchem.202000995 %V 26 %X Depending on the connectivity of solubilizing oligoethylene glycol (OEG) side chains to the π‐cores of amphiphilic naphthalene and perylene bisimide dyes, self‐assembly in water occurs either upon heating or cooling. Herein, we show that this effect originates from differences in the enwrapping capability of the π‐cores by the OEG chains. Rylene bisimides bearing phenyl substituents with three OEG chains attached directly to the hydrophobic π‐cores are strongly sequestered by the OEG chains. These molecules self‐assemble at elevated temperatures in an entropy‐driven process according to temperature‐ and concentration‐dependent UV/Vis spectroscopy and calorimetric dilution studies. In contrast, for rylene bisimides in which phenyl substituents with three OEG chains are attached via a methylene spacer, leading to much weaker sequestration, self‐assembly originates upon cooling in an enthalpy‐driven process. Our explanation for this controversial behavior is that the aggregation in the latter case is dictated by the release of “high energy water” from the hydrophobic π‐surfaces as well as dispersion interactions between the π‐scaffolds which drive the self‐assembly in an enthalpically driven process. In contrast, for the former case we suggest that in addition to the conventional explanation of a dehydration of hydrogen‐bonded water molecules from OEG units it is in particular the increase in conformational entropy of back‐folded OEG side chains upon aggregation that provides the pronounced gain in entropy that drives the aggregation process. Thus, our studies revealed that a subtle change in the attachment of solubilizing substituents can switch the thermodynamic signature for the self‐assembly of amphiphilic dyes in water from enthalpy‐ to entropy‐driven.
• Bowl-Shaped Naphthalimide-Annulated Corannulene as Nonfullerene Acceptor in Organic Solar Cells. Menekse, Kaan; Renner, Rebecca; Mahlmeister, Bernhard; Stolte, Matthias; Würthner, Frank. In Organic Materials, 02(03), pp. 229–234. 2020.
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  An electron-poor bowl-shaped naphthalimide-annulated corannulene with branched alkyl residues in the imide position was synthesized by a palladium-catalyzed cross-coupling annulation sequence. This dipolar compound exhibits strong absorption in the visible range along with a low-lying LUMO level at –3.85 eV, enabling n-type charge transport in organic thin-film transistors. Furthermore, we processed inverted bulk-heterojunction solar cells in combination with the two donor polymers PCE–10 and PM6 to achieve open-circuit voltages up to 1.04 V. By using a blend of the self-assembled naphthalimide-annulated corannulene and PCE–10, we were able to obtain a power conversion efficiency of up to 2.1%, which is to the best of our knowledge the highest reported value for a corannulene-based organic solar cell to date.

  @article{menekse2020bowlshaped, abstract = {An electron-poor bowl-shaped naphthalimide-annulated corannulene with branched alkyl residues in the imide position was synthesized by a palladium-catalyzed cross-coupling annulation sequence. This dipolar compound exhibits strong absorption in the visible range along with a low-lying LUMO level at –3.85 eV, enabling n-type charge transport in organic thin-film transistors. Furthermore, we processed inverted bulk-heterojunction solar cells in combination with the two donor polymers PCE–10 and PM6 to achieve open-circuit voltages up to 1.04 V. By using a blend of the self-assembled naphthalimide-annulated corannulene and PCE–10, we were able to obtain a power conversion efficiency of up to 2.1%, which is to the best of our knowledge the highest reported value for a corannulene-based organic solar cell to date.}, author = {Menekse, Kaan and Renner, Rebecca and Mahlmeister, Bernhard and Stolte, Matthias and Würthner, Frank}, journal = {Organic Materials}, keywords = {myown}, number = {03}, pages = {229-234}, title = {Bowl-Shaped Naphthalimide-Annulated Corannulene as Nonfullerene Acceptor in Organic Solar Cells}, volume = {02}, year = 2020 }

  %0 Journal Article %1 menekse2020bowlshaped %A Menekse, Kaan %A Renner, Rebecca %A Mahlmeister, Bernhard %A Stolte, Matthias %A Würthner, Frank %D 2020 %J Organic Materials %N 03 %P 229-234 %R 10.1055/s-0040-1714283 %T Bowl-Shaped Naphthalimide-Annulated Corannulene as Nonfullerene Acceptor in Organic Solar Cells %V 02 %X An electron-poor bowl-shaped naphthalimide-annulated corannulene with branched alkyl residues in the imide position was synthesized by a palladium-catalyzed cross-coupling annulation sequence. This dipolar compound exhibits strong absorption in the visible range along with a low-lying LUMO level at –3.85 eV, enabling n-type charge transport in organic thin-film transistors. Furthermore, we processed inverted bulk-heterojunction solar cells in combination with the two donor polymers PCE–10 and PM6 to achieve open-circuit voltages up to 1.04 V. By using a blend of the self-assembled naphthalimide-annulated corannulene and PCE–10, we were able to obtain a power conversion efficiency of up to 2.1%, which is to the best of our knowledge the highest reported value for a corannulene-based organic solar cell to date.
• Effects of Photosensitizers and Reaction Media on Light-Driven Water Oxidation with Trinuclear Ruthenium Macrocycles. Meza-Chincha, Ana-Lucia; Schindler, Dorothee; Natali, Mirco; Würthner, Frank. In ChemPhotoChem, 5(2), pp. 173–183. 2020.
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  Photocatalytic water oxidation is a promising process for the production of solar fuels and the elucidation of factors that influence this process is of high significance. Thus, we have studied in detail light‐driven water oxidation with a trinuclear Ru(bda) (bda: 2,2’‐bipyridine‐6,6’‐dicarboxylate) macrocycle MC3 and its highly water soluble derivative m‐CH2NMe2‐MC3 using a series of ruthenium tris(bipyridine) complexes as photosensitizers under varied reaction conditions. Our investigations showed that the catalytic activities of these Ru macrocycles are significantly affected by the choice of photosensitizer (PS) and reaction media, in addition to buffer concentration, light intensity and concentration of the sensitizer. Our steady‐state and transient spectroscopic studies revealed that the photocatalytic performance of trinuclear Ru(bda) macrocycles is not limited by their intrinsic catalytic activities but rather by the efficiency of photogeneration of oxidant PS+ and its ability to act as an oxidizing agent to the catalysts as both are strongly dependent on the choice of photosensitizer and the amount of employed organic co‐solvent.

  @article{Meza_Chincha_2020, abstract = {Photocatalytic water oxidation is a promising process for the production of solar fuels and the elucidation of factors that influence this process is of high significance. Thus, we have studied in detail light‐driven water oxidation with a trinuclear Ru(bda) (bda: 2,2’‐bipyridine‐6,6’‐dicarboxylate) macrocycle MC3 and its highly water soluble derivative m‐CH2NMe2‐MC3 using a series of ruthenium tris(bipyridine) complexes as photosensitizers under varied reaction conditions. Our investigations showed that the catalytic activities of these Ru macrocycles are significantly affected by the choice of photosensitizer (PS) and reaction media, in addition to buffer concentration, light intensity and concentration of the sensitizer. Our steady‐state and transient spectroscopic studies revealed that the photocatalytic performance of trinuclear Ru(bda) macrocycles is not limited by their intrinsic catalytic activities but rather by the efficiency of photogeneration of oxidant PS+ and its ability to act as an oxidizing agent to the catalysts as both are strongly dependent on the choice of photosensitizer and the amount of employed organic co‐solvent.}, author = {Meza-Chincha, Ana-Lucia and Schindler, Dorothee and Natali, Mirco and Würthner, Frank}, journal = {ChemPhotoChem}, keywords = {myown}, month = {08}, number = 2, pages = {173-183}, publisher = {Wiley}, title = {Effects of Photosensitizers and Reaction Media on Light-Driven Water Oxidation with Trinuclear Ruthenium Macrocycles}, volume = 5, year = 2020 }

  %0 Journal Article %1 Meza_Chincha_2020 %A Meza-Chincha, Ana-Lucia %A Schindler, Dorothee %A Natali, Mirco %A Würthner, Frank %D 2020 %I Wiley %J ChemPhotoChem %N 2 %P 173-183 %R 10.1002/cptc.202000133 %T Effects of Photosensitizers and Reaction Media on Light-Driven Water Oxidation with Trinuclear Ruthenium Macrocycles %U https://doi.org/10.1002%2Fcptc.202000133 %V 5 %X Photocatalytic water oxidation is a promising process for the production of solar fuels and the elucidation of factors that influence this process is of high significance. Thus, we have studied in detail light‐driven water oxidation with a trinuclear Ru(bda) (bda: 2,2’‐bipyridine‐6,6’‐dicarboxylate) macrocycle MC3 and its highly water soluble derivative m‐CH2NMe2‐MC3 using a series of ruthenium tris(bipyridine) complexes as photosensitizers under varied reaction conditions. Our investigations showed that the catalytic activities of these Ru macrocycles are significantly affected by the choice of photosensitizer (PS) and reaction media, in addition to buffer concentration, light intensity and concentration of the sensitizer. Our steady‐state and transient spectroscopic studies revealed that the photocatalytic performance of trinuclear Ru(bda) macrocycles is not limited by their intrinsic catalytic activities but rather by the efficiency of photogeneration of oxidant PS+ and its ability to act as an oxidizing agent to the catalysts as both are strongly dependent on the choice of photosensitizer and the amount of employed organic co‐solvent.
• Impact of substituents on molecular properties and catalytic activities of trinuclear Ru macrocycles in water oxidation. Meza-Chincha, Ana-Lucia; Lindner, Joachim O.; Schindler, Dorothee; Schmidt, David; Krause, Ana-Maria; Röhr, Merle I. S.; Mitrić, Roland; Würthner, Frank. In Chem. Sci., 11(29), pp. 7654–7664. 2020.
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  Herein we report a broad series of new trinuclear supramolecular Ru(bda) macrocycles bearing different substituents at the axial or equatorial ligands which enabled investigation of substituent effects on the catalytic activities in chemical and photocatalytic water oxidation. Our detailed investigations revealed that the activities of these functionalized macrocycles in water oxidation are significantly affected by the position at which the substituents were introduced. Interestingly, this effect could not be explained based on the redox properties of the catalysts since these are not markedly influenced by the functionalization of the ligands. Instead, detailed investigations by X-ray crystal structure analysis and theoretical simulations showed that conformational changes imparted by the substituents are responsible for the variation of catalytic activities of the Ru macrocycles. For the first time, macrocyclic structure of this class of water oxidation catalysts is unequivocally confirmed and experimental indication for a hydrogen-bonded water network present in the cavity of the macrocycles is provided by crystal structure analysis. We ascribe the high catalytic efficiency of our Ru(bda) macrocycles to cooperative proton abstractions facilitated by such a network of preorganized water molecules in their cavity, which is reminiscent of catalytic activities of enzymes at active sites.

  @article{D0SC01097A, abstract = {Herein we report a broad series of new trinuclear supramolecular Ru(bda) macrocycles bearing different substituents at the axial or equatorial ligands which enabled investigation of substituent effects on the catalytic activities in chemical and photocatalytic water oxidation. Our detailed investigations revealed that the activities of these functionalized macrocycles in water oxidation are significantly affected by the position at which the substituents were introduced. Interestingly{,} this effect could not be explained based on the redox properties of the catalysts since these are not markedly influenced by the functionalization of the ligands. Instead{,} detailed investigations by X-ray crystal structure analysis and theoretical simulations showed that conformational changes imparted by the substituents are responsible for the variation of catalytic activities of the Ru macrocycles. For the first time{,} macrocyclic structure of this class of water oxidation catalysts is unequivocally confirmed and experimental indication for a hydrogen-bonded water network present in the cavity of the macrocycles is provided by crystal structure analysis. We ascribe the high catalytic efficiency of our Ru(bda) macrocycles to cooperative proton abstractions facilitated by such a network of preorganized water molecules in their cavity{,} which is reminiscent of catalytic activities of enzymes at active sites.}, author = {Meza-Chincha, Ana-Lucia and Lindner, Joachim O. and Schindler, Dorothee and Schmidt, David and Krause, Ana-Maria and Röhr, Merle I. S. and Mitrić, Roland and Würthner, Frank}, journal = {Chem. Sci.}, keywords = {myown}, number = 29, pages = {7654-7664}, publisher = {The Royal Society of Chemistry}, title = {Impact of substituents on molecular properties and catalytic activities of trinuclear Ru macrocycles in water oxidation}, volume = 11, year = 2020 }

  %0 Journal Article %1 D0SC01097A %A Meza-Chincha, Ana-Lucia %A Lindner, Joachim O. %A Schindler, Dorothee %A Schmidt, David %A Krause, Ana-Maria %A Röhr, Merle I. S. %A Mitrić, Roland %A Würthner, Frank %D 2020 %I The Royal Society of Chemistry %J Chem. Sci. %N 29 %P 7654-7664 %R 10.1039/D0SC01097A %T Impact of substituents on molecular properties and catalytic activities of trinuclear Ru macrocycles in water oxidation %U http://dx.doi.org/10.1039/D0SC01097A %V 11 %X Herein we report a broad series of new trinuclear supramolecular Ru(bda) macrocycles bearing different substituents at the axial or equatorial ligands which enabled investigation of substituent effects on the catalytic activities in chemical and photocatalytic water oxidation. Our detailed investigations revealed that the activities of these functionalized macrocycles in water oxidation are significantly affected by the position at which the substituents were introduced. Interestingly, this effect could not be explained based on the redox properties of the catalysts since these are not markedly influenced by the functionalization of the ligands. Instead, detailed investigations by X-ray crystal structure analysis and theoretical simulations showed that conformational changes imparted by the substituents are responsible for the variation of catalytic activities of the Ru macrocycles. For the first time, macrocyclic structure of this class of water oxidation catalysts is unequivocally confirmed and experimental indication for a hydrogen-bonded water network present in the cavity of the macrocycles is provided by crystal structure analysis. We ascribe the high catalytic efficiency of our Ru(bda) macrocycles to cooperative proton abstractions facilitated by such a network of preorganized water molecules in their cavity, which is reminiscent of catalytic activities of enzymes at active sites.
• Hydrogen bond-rigidified planar squaraine dye and its electronic and organic semiconductor properties. Maeda, Takeshi; Liess, Andreas; Kudzus, Astrid; Krause, Ana-Maria; Stolte, Matthias; Amitani, Hitoshi; Yagi, Shigeyuki; Fujiwara, Hideki; Würthner, Frank. In Chem. Commun., 56(68), pp. 9890–9893. 2020.
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  The one-step reaction of a dicyanovinyl-functionalized squaric acid with Fischer bases afforded C2v symmetric squaraine dyes with rigid planar structures due to intramolecular N–H⋯O hydrogen bonds. Dense molecular packing, decrease of HOMO level, and sufficient thermal stability for sublimation enabled vacuum-processed OTFTs with hole mobility up to 0.32 cm2 V−1 s−1 and current on/off ratio of 106.

  @article{D0CC04306K, abstract = {The one-step reaction of a dicyanovinyl-functionalized squaric acid with Fischer bases afforded C2v symmetric squaraine dyes with rigid planar structures due to intramolecular N–H⋯O hydrogen bonds. Dense molecular packing{,} decrease of HOMO level{,} and sufficient thermal stability for sublimation enabled vacuum-processed OTFTs with hole mobility up to 0.32 cm2 V−1 s−1 and current on/off ratio of 106.}, author = {Maeda, Takeshi and Liess, Andreas and Kudzus, Astrid and Krause, Ana-Maria and Stolte, Matthias and Amitani, Hitoshi and Yagi, Shigeyuki and Fujiwara, Hideki and Würthner, Frank}, journal = {Chem. Commun.}, keywords = {myown}, number = 68, pages = {9890-9893}, publisher = {The Royal Society of Chemistry}, title = {Hydrogen bond-rigidified planar squaraine dye and its electronic and organic semiconductor properties}, volume = 56, year = 2020 }

  %0 Journal Article %1 D0CC04306K %A Maeda, Takeshi %A Liess, Andreas %A Kudzus, Astrid %A Krause, Ana-Maria %A Stolte, Matthias %A Amitani, Hitoshi %A Yagi, Shigeyuki %A Fujiwara, Hideki %A Würthner, Frank %D 2020 %I The Royal Society of Chemistry %J Chem. Commun. %N 68 %P 9890-9893 %R 10.1039/D0CC04306K %T Hydrogen bond-rigidified planar squaraine dye and its electronic and organic semiconductor properties %U http://dx.doi.org/10.1039/D0CC04306K %V 56 %X The one-step reaction of a dicyanovinyl-functionalized squaric acid with Fischer bases afforded C2v symmetric squaraine dyes with rigid planar structures due to intramolecular N–H⋯O hydrogen bonds. Dense molecular packing, decrease of HOMO level, and sufficient thermal stability for sublimation enabled vacuum-processed OTFTs with hole mobility up to 0.32 cm2 V−1 s−1 and current on/off ratio of 106.
• Stepwise Folding and Self-Assembly of a Merocyanine Folda-Pentamer. Hu, Xiaobo; Lindner, Joachim; Würthner, Frank. In J. Am. Chem. Soc., 142(7), pp. 3321–3325. 2020.
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  Here we report a synthetic protocol toward a merocyanine (MC) pentamer 1 which represents the first merocyanine oligomer longer than a dimer. By continuously decreasing the solvent polarity, we demonstrate the stepwise folding from partially folded monomeric and dimeric MC subunits (in chloroform) up to the full pentamer π-stack (in 75% methylcyclohexane/25% chloroform) and a subsequent self-assembly of pentamer 1 into larger aggregates (in 80% methylcyclohexane/20% chloroform). This hierarchical structure formation process became possible due to the predominant dipole–dipole interactions among MC dyes that allowed for a precise modulation of the energy landscape by the solvent polarity. This unprecedented stepwise control of dye assembly via hierarchical dipole–dipole interactions opens the door for a more precise control of dye–dye interactions in artificial multichromophoric ensembles.

  @article{noauthororeditor, abstract = {Here we report a synthetic protocol toward a merocyanine (MC) pentamer 1 which represents the first merocyanine oligomer longer than a dimer. By continuously decreasing the solvent polarity, we demonstrate the stepwise folding from partially folded monomeric and dimeric MC subunits (in chloroform) up to the full pentamer π-stack (in 75% methylcyclohexane/25% chloroform) and a subsequent self-assembly of pentamer 1 into larger aggregates (in 80% methylcyclohexane/20% chloroform). This hierarchical structure formation process became possible due to the predominant dipole–dipole interactions among MC dyes that allowed for a precise modulation of the energy landscape by the solvent polarity. This unprecedented stepwise control of dye assembly via hierarchical dipole–dipole interactions opens the door for a more precise control of dye–dye interactions in artificial multichromophoric ensembles.}, author = {Hu, Xiaobo and Lindner, Joachim and Würthner, Frank}, journal = {J. Am. Chem. Soc.}, keywords = {myown}, month = {02}, number = 7, pages = {3321-3325}, title = {Stepwise Folding and Self-Assembly of a Merocyanine Folda-Pentamer}, volume = 142, year = 2020 }

  %0 Journal Article %1 noauthororeditor %A Hu, Xiaobo %A Lindner, Joachim %A Würthner, Frank %D 2020 %J J. Am. Chem. Soc. %N 7 %P 3321-3325 %R 10.1021/jacs.9b12599 %T Stepwise Folding and Self-Assembly of a Merocyanine Folda-Pentamer %U https://pubs.acs.org/doi/full/10.1021/jacs.9b12599 %V 142 %X Here we report a synthetic protocol toward a merocyanine (MC) pentamer 1 which represents the first merocyanine oligomer longer than a dimer. By continuously decreasing the solvent polarity, we demonstrate the stepwise folding from partially folded monomeric and dimeric MC subunits (in chloroform) up to the full pentamer π-stack (in 75% methylcyclohexane/25% chloroform) and a subsequent self-assembly of pentamer 1 into larger aggregates (in 80% methylcyclohexane/20% chloroform). This hierarchical structure formation process became possible due to the predominant dipole–dipole interactions among MC dyes that allowed for a precise modulation of the energy landscape by the solvent polarity. This unprecedented stepwise control of dye assembly via hierarchical dipole–dipole interactions opens the door for a more precise control of dye–dye interactions in artificial multichromophoric ensembles.
• NIR-Absorbing π-Extended Azulene: Non-Alternant Isomer of Terrylene Bisimide. Pigulski, Bart\lomiej; Shoyama, Kazutaka; Würthner, Frank. In Angew. Chem. Int. Ed., 59(37), pp. 15908–15912. 2020.
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  The first planar π‐extended azulene that retains aromaticity of odd‐membered rings was synthesized by [3+3] peri‐annulation of two naphthalene imides at both long‐edge sides of azulene. Using bromination and subsequent nucleophilic substitution by methoxide and morpholine, selective functionalization of the π‐extended azulene was achieved. Whilst these new azulenes can be regarded as isomers of terrylene bisimide they exhibit entirely different properties, which include very narrow optical and electrochemical gaps. DFT, TD‐DFT, as well as nucleus‐independent chemical shift calculations were applied to explain the structural and functional properties of these new π scaffolds. Furthermore, X‐ray crystallography confirmed the planarity of the reported π‐scaffolds and aromaticity of their azulene moiety.

  @article{Pigulski_2020, abstract = {The first planar π‐extended azulene that retains aromaticity of odd‐membered rings was synthesized by [3+3] peri‐annulation of two naphthalene imides at both long‐edge sides of azulene. Using bromination and subsequent nucleophilic substitution by methoxide and morpholine, selective functionalization of the π‐extended azulene was achieved. Whilst these new azulenes can be regarded as isomers of terrylene bisimide they exhibit entirely different properties, which include very narrow optical and electrochemical gaps. DFT, TD‐DFT, as well as nucleus‐independent chemical shift calculations were applied to explain the structural and functional properties of these new π scaffolds. Furthermore, X‐ray crystallography confirmed the planarity of the reported π‐scaffolds and aromaticity of their azulene moiety.}, author = {Pigulski, Bart{\l}omiej and Shoyama, Kazutaka and Würthner, Frank}, journal = {Angew. Chem. Int. Ed.}, keywords = {myown}, month = {06}, number = 37, pages = {15908-15912}, publisher = {Wiley}, title = {NIR-Absorbing π-Extended Azulene: Non-Alternant Isomer of Terrylene Bisimide}, volume = 59, year = 2020 }

  %0 Journal Article %1 Pigulski_2020 %A Pigulski, Bart\lomiej %A Shoyama, Kazutaka %A Würthner, Frank %D 2020 %I Wiley %J Angew. Chem. Int. Ed. %N 37 %P 15908-15912 %R 10.1002/anie.202005376 %T NIR-Absorbing π-Extended Azulene: Non-Alternant Isomer of Terrylene Bisimide %U https://doi.org/10.1002%2Fanie.202005376 %V 59 %X The first planar π‐extended azulene that retains aromaticity of odd‐membered rings was synthesized by [3+3] peri‐annulation of two naphthalene imides at both long‐edge sides of azulene. Using bromination and subsequent nucleophilic substitution by methoxide and morpholine, selective functionalization of the π‐extended azulene was achieved. Whilst these new azulenes can be regarded as isomers of terrylene bisimide they exhibit entirely different properties, which include very narrow optical and electrochemical gaps. DFT, TD‐DFT, as well as nucleus‐independent chemical shift calculations were applied to explain the structural and functional properties of these new π scaffolds. Furthermore, X‐ray crystallography confirmed the planarity of the reported π‐scaffolds and aromaticity of their azulene moiety.
• Control of self-assembly pathways toward conglomerate and racemic supramolecular polymers. Wehner, Marius; Röhr, Merle Insa Silja; Stepanenko, Vladimir; Würthner, Frank. In Nat. Commun., 11(1). 2020.
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  Homo- and heterochiral aggregation during crystallization of organic molecules has significance both for fundamental questions related to the origin of life as well as for the separation of homochiral compounds from their racemates in industrial processes. Herein, we analyse these phenomena at the lowest level of hierarchy – that is the self-assembly of a racemic mixture of (R,R)- and (S,S)-PBI into 1D supramolecular polymers. By a combination of UV/vis and NMR spectroscopy as well as atomic force microscopy, we demonstrate that homochiral aggregation of the racemic mixture leads to the formation of two types of supramolecular conglomerates under kinetic control, while under thermodynamic control heterochiral aggregation is preferred, affording a racemic supramolecular polymer. FT-IR spectroscopy and quantum-chemical calculations reveal unique packing arrangements and hydrogen-bonding patterns within these supramolecular polymers. Time-, concentration- and temperature-dependent UV/vis experiments provide further insights into the kinetic and thermodynamic control of the conglomerate and racemic supramolecular polymer formation

  @article{Wehner_2020, abstract = {Homo- and heterochiral aggregation during crystallization of organic molecules has significance both for fundamental questions related to the origin of life as well as for the separation of homochiral compounds from their racemates in industrial processes. Herein, we analyse these phenomena at the lowest level of hierarchy – that is the self-assembly of a racemic mixture of (R,R)- and (S,S)-PBI into 1D supramolecular polymers. By a combination of UV/vis and NMR spectroscopy as well as atomic force microscopy, we demonstrate that homochiral aggregation of the racemic mixture leads to the formation of two types of supramolecular conglomerates under kinetic control, while under thermodynamic control heterochiral aggregation is preferred, affording a racemic supramolecular polymer. FT-IR spectroscopy and quantum-chemical calculations reveal unique packing arrangements and hydrogen-bonding patterns within these supramolecular polymers. Time-, concentration- and temperature-dependent UV/vis experiments provide further insights into the kinetic and thermodynamic control of the conglomerate and racemic supramolecular polymer formation}, author = {Wehner, Marius and Röhr, Merle Insa Silja and Stepanenko, Vladimir and Würthner, Frank}, journal = {Nat. Commun.}, keywords = {myown}, month = 10, number = 1, publisher = {Springer Science and Business Media {LLC}}, title = {Control of self-assembly pathways toward conglomerate and racemic supramolecular polymers}, volume = 11, year = 2020 }

  %0 Journal Article %1 Wehner_2020 %A Wehner, Marius %A Röhr, Merle Insa Silja %A Stepanenko, Vladimir %A Würthner, Frank %D 2020 %I Springer Science and Business Media LLC %J Nat. Commun. %N 1 %R 10.1038/s41467-020-19189-8 %T Control of self-assembly pathways toward conglomerate and racemic supramolecular polymers %U https://doi.org/10.1038%2Fs41467-020-19189-8 %V 11 %X Homo- and heterochiral aggregation during crystallization of organic molecules has significance both for fundamental questions related to the origin of life as well as for the separation of homochiral compounds from their racemates in industrial processes. Herein, we analyse these phenomena at the lowest level of hierarchy – that is the self-assembly of a racemic mixture of (R,R)- and (S,S)-PBI into 1D supramolecular polymers. By a combination of UV/vis and NMR spectroscopy as well as atomic force microscopy, we demonstrate that homochiral aggregation of the racemic mixture leads to the formation of two types of supramolecular conglomerates under kinetic control, while under thermodynamic control heterochiral aggregation is preferred, affording a racemic supramolecular polymer. FT-IR spectroscopy and quantum-chemical calculations reveal unique packing arrangements and hydrogen-bonding patterns within these supramolecular polymers. Time-, concentration- and temperature-dependent UV/vis experiments provide further insights into the kinetic and thermodynamic control of the conglomerate and racemic supramolecular polymer formation
• Conformation and Aromaticity Switching in a Curved Non-Alternant sp2 Carbon Scaffold. Zhu, Chongwei; Shoyama, Kazutaka; Würthner, Frank. In Angew. Chem. Int. Ed., 59(48), pp. 21505–21509. 2020.
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  A curved sp2 carbon scaffold containing fused pentagon and heptagon units (1) was synthesized by Pd‐catalyzed [5+2] annulation from a 3,9‐diboraperylene precursor and shows two reversible oxidation processes at low redox potential, accompanied by a butterfly‐like motion. Stepwise oxidation produced radical cation 1.+ and dication 12+. In the crystal structure, 1 exhibits a chiral cisoid conformation and partial π‐overlap between the enantiomers. For the radical cation 1.+, a less curved cisoid conformation is observed with a π‐dimer‐type arrangement. 12+ adopts a more planar structure with transoid conformation and slip‐stacked π‐overlap with closest neighbors. We also observed an intermolecular mixed‐valence complex of 1⋅(1.+)3 that has a huge trigonal unit cell [(1)72(SbF6)54⋅(hexane)101] and hexagonal columnar stacks. In addition to the conformational change, the aromaticity of 1 changes from localized to delocalized, as demonstrated by AICD and NICS(1)zz calculations.

  @article{Zhu_2020, abstract = {A curved sp2 carbon scaffold containing fused pentagon and heptagon units (1) was synthesized by Pd‐catalyzed [5+2] annulation from a 3,9‐diboraperylene precursor and shows two reversible oxidation processes at low redox potential, accompanied by a butterfly‐like motion. Stepwise oxidation produced radical cation 1.+ and dication 12+. In the crystal structure, 1 exhibits a chiral cisoid conformation and partial π‐overlap between the enantiomers. For the radical cation 1.+, a less curved cisoid conformation is observed with a π‐dimer‐type arrangement. 12+ adopts a more planar structure with transoid conformation and slip‐stacked π‐overlap with closest neighbors. We also observed an intermolecular mixed‐valence complex of 1⋅(1.+)3 that has a huge trigonal unit cell [(1)72(SbF6)54⋅(hexane)101] and hexagonal columnar stacks. In addition to the conformational change, the aromaticity of 1 changes from localized to delocalized, as demonstrated by AICD and NICS(1)zz calculations.}, author = {Zhu, Chongwei and Shoyama, Kazutaka and Würthner, Frank}, journal = {Angew. Chem. Int. Ed.}, keywords = {myown}, month = {09}, number = 48, pages = {21505–21509}, publisher = {Wiley}, title = {Conformation and Aromaticity Switching in a Curved Non-Alternant sp2 Carbon Scaffold}, volume = 59, year = 2020 }

  %0 Journal Article %1 Zhu_2020 %A Zhu, Chongwei %A Shoyama, Kazutaka %A Würthner, Frank %D 2020 %I Wiley %J Angew. Chem. Int. Ed. %N 48 %P 21505--21509 %R 10.1002/anie.202010077 %T Conformation and Aromaticity Switching in a Curved Non-Alternant sp2 Carbon Scaffold %U https://onlinelibrary.wiley.com/doi/10.1002/anie.202010077 %V 59 %X A curved sp2 carbon scaffold containing fused pentagon and heptagon units (1) was synthesized by Pd‐catalyzed [5+2] annulation from a 3,9‐diboraperylene precursor and shows two reversible oxidation processes at low redox potential, accompanied by a butterfly‐like motion. Stepwise oxidation produced radical cation 1.+ and dication 12+. In the crystal structure, 1 exhibits a chiral cisoid conformation and partial π‐overlap between the enantiomers. For the radical cation 1.+, a less curved cisoid conformation is observed with a π‐dimer‐type arrangement. 12+ adopts a more planar structure with transoid conformation and slip‐stacked π‐overlap with closest neighbors. We also observed an intermolecular mixed‐valence complex of 1⋅(1.+)3 that has a huge trigonal unit cell [(1)72(SbF6)54⋅(hexane)101] and hexagonal columnar stacks. In addition to the conformational change, the aromaticity of 1 changes from localized to delocalized, as demonstrated by AICD and NICS(1)zz calculations.
• Base-Assisted Imidization: A Synthetic Method for the Introduction of Bulky Imide Substituents to Control Packing and Optical Properties of Naphthalene and Perylene Imides. Mahl, Magnus; Shoyama, Kazutaka; Krause, Ana-Maria; Schmidt, David; Würthner, Frank. In Angew. Chem. Int. Ed., 59(32), pp. 13401–13405. 2020.
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  We report the direct imidization of naphthalene and perylene dicarboxylic anhydrides/esters with bulky ortho ,ortho‐diaryl‐ and ortho ,ortho‐dialkynylaniline derivatives. This imidization method uses n‐butyllithium as a strong base to increase the reactivity of bulky amine derivatives, proceeds under mild reaction conditions, requires only stoichiometric amounts of reactants and gives straightforward access to new sterically crowded rylene dicarboximides. Mechanistic investigations suggest an isoimide as intermediary product, which was converted to the corresponding imide upon addition of an aqueous base. Single‐crystal X‐ray diffraction analyses reveal dimeric packing motifs for monoimides, while two‐side shielded bisimides crystallize in isolated molecules without close π–π‐interactions. Spectroscopic investigations disclose the influence of the bulky substituents on the optical properties in the solid state.

  @article{Mahl_2020, abstract = {We report the direct imidization of naphthalene and perylene dicarboxylic anhydrides/esters with bulky ortho ,ortho‐diaryl‐ and ortho ,ortho‐dialkynylaniline derivatives. This imidization method uses n‐butyllithium as a strong base to increase the reactivity of bulky amine derivatives, proceeds under mild reaction conditions, requires only stoichiometric amounts of reactants and gives straightforward access to new sterically crowded rylene dicarboximides. Mechanistic investigations suggest an isoimide as intermediary product, which was converted to the corresponding imide upon addition of an aqueous base. Single‐crystal X‐ray diffraction analyses reveal dimeric packing motifs for monoimides, while two‐side shielded bisimides crystallize in isolated molecules without close π–π‐interactions. Spectroscopic investigations disclose the influence of the bulky substituents on the optical properties in the solid state.}, author = {Mahl, Magnus and Shoyama, Kazutaka and Krause, Ana-Maria and Schmidt, David and Würthner, Frank}, journal = {Angew. Chem. Int. Ed.}, keywords = {myown}, month = {05}, number = 32, pages = {13401–13405}, publisher = {Wiley}, title = {Base-Assisted Imidization: A Synthetic Method for the Introduction of Bulky Imide Substituents to Control Packing and Optical Properties of Naphthalene and Perylene Imides}, volume = 59, year = 2020 }

  %0 Journal Article %1 Mahl_2020 %A Mahl, Magnus %A Shoyama, Kazutaka %A Krause, Ana-Maria %A Schmidt, David %A Würthner, Frank %D 2020 %I Wiley %J Angew. Chem. Int. Ed. %N 32 %P 13401--13405 %R 10.1002/anie.202004965 %T Base-Assisted Imidization: A Synthetic Method for the Introduction of Bulky Imide Substituents to Control Packing and Optical Properties of Naphthalene and Perylene Imides %U https://doi.org/10.1002%2Fanie.202004965 %V 59 %X We report the direct imidization of naphthalene and perylene dicarboxylic anhydrides/esters with bulky ortho ,ortho‐diaryl‐ and ortho ,ortho‐dialkynylaniline derivatives. This imidization method uses n‐butyllithium as a strong base to increase the reactivity of bulky amine derivatives, proceeds under mild reaction conditions, requires only stoichiometric amounts of reactants and gives straightforward access to new sterically crowded rylene dicarboximides. Mechanistic investigations suggest an isoimide as intermediary product, which was converted to the corresponding imide upon addition of an aqueous base. Single‐crystal X‐ray diffraction analyses reveal dimeric packing motifs for monoimides, while two‐side shielded bisimides crystallize in isolated molecules without close π–π‐interactions. Spectroscopic investigations disclose the influence of the bulky substituents on the optical properties in the solid state.
• Naphthalene diimide-amino acid conjugates as novel fluorimetric and CD probes for differentiation between ds-DNA and ds-RNA. Weissenstein, Annike; Vysotsky, Myroslav O; Piantanida, Ivo; Würthner, Frank. In Beilstein J. Org. Chem., 16, pp. 2032–2045. 2020.
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  Two novel unnatural amino acids, prepared by linking a dicationic purple-coloured and fluorescent naphthalene diimide (NDI) at core position to amino acid side chains of variable length, strongly interacted with ds-DNA/RNA by threading intercalation. Different from a reference NDI dye with identical visible range absorbance (520–540 nm) and Stokes shifts in emission (+60 nm, quantum yield > 0.2), only these amino acid–NDI conjugates showed selective fluorimetric response for GC-DNA in respect to AT(U)-polynucleotides. The DNA/RNA binding-induced circular dichroism (ICD) response of NDI at 450–550 nm strongly depended on the length and rigidity of the linker to the amino acid unit, which controls the orientation of the NDI unit inside within the intercalative binding site. The ICD selectivity also depends on the type of polynucleotide, thus the studied NDI dyes act as dual fluorimetric/ICD probes for sensing the difference between here used GC-DNA, AT-DNA and AU-RNA.

  @article{Wei_enstein_2020, abstract = {Two novel unnatural amino acids, prepared by linking a dicationic purple-coloured and fluorescent naphthalene diimide (NDI) at core position to amino acid side chains of variable length, strongly interacted with ds-DNA/RNA by threading intercalation. Different from a reference NDI dye with identical visible range absorbance (520–540 nm) and Stokes shifts in emission (+60 nm, quantum yield > 0.2), only these amino acid–NDI conjugates showed selective fluorimetric response for GC-DNA in respect to AT(U)-polynucleotides. The DNA/RNA binding-induced circular dichroism (ICD) response of NDI at 450–550 nm strongly depended on the length and rigidity of the linker to the amino acid unit, which controls the orientation of the NDI unit inside within the intercalative binding site. The ICD selectivity also depends on the type of polynucleotide, thus the studied NDI dyes act as dual fluorimetric/ICD probes for sensing the difference between here used GC-DNA, AT-DNA and AU-RNA.}, author = {Weissenstein, Annike and Vysotsky, Myroslav O and Piantanida, Ivo and Würthner, Frank}, journal = {Beilstein J. Org. Chem.}, keywords = {myown}, month = {08}, pages = {2032–2045}, publisher = {Beilstein Institut}, title = {Naphthalene diimide-amino acid conjugates as novel fluorimetric and CD probes for differentiation between ds-DNA and ds-RNA}, volume = 16, year = 2020 }

  %0 Journal Article %1 Wei_enstein_2020 %A Weissenstein, Annike %A Vysotsky, Myroslav O %A Piantanida, Ivo %A Würthner, Frank %D 2020 %I Beilstein Institut %J Beilstein J. Org. Chem. %P 2032--2045 %R 10.3762/bjoc.16.170 %T Naphthalene diimide-amino acid conjugates as novel fluorimetric and CD probes for differentiation between ds-DNA and ds-RNA %U https://doi.org/10.3762%2Fbjoc.16.170 %V 16 %X Two novel unnatural amino acids, prepared by linking a dicationic purple-coloured and fluorescent naphthalene diimide (NDI) at core position to amino acid side chains of variable length, strongly interacted with ds-DNA/RNA by threading intercalation. Different from a reference NDI dye with identical visible range absorbance (520–540 nm) and Stokes shifts in emission (+60 nm, quantum yield > 0.2), only these amino acid–NDI conjugates showed selective fluorimetric response for GC-DNA in respect to AT(U)-polynucleotides. The DNA/RNA binding-induced circular dichroism (ICD) response of NDI at 450–550 nm strongly depended on the length and rigidity of the linker to the amino acid unit, which controls the orientation of the NDI unit inside within the intercalative binding site. The ICD selectivity also depends on the type of polynucleotide, thus the studied NDI dyes act as dual fluorimetric/ICD probes for sensing the difference between here used GC-DNA, AT-DNA and AU-RNA.
• Efficient Electrochemical Water Oxidation by a Trinuclear Ru(bda) Macrocycle Immobilized on Multi-Walled Carbon Nanotube Electrodes. Schindler, Dorothee; Gil-Sepulcre, Marcos; Lindner, Joachim O.; Stepanenko, Vladimir; Moonshiram, Dooshaye; Llobet, Antoni; Würthner, Frank. In Adv. Energy Mater., 10(43), p. 2002329. 2020.
  • [ Abstract ]
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  Catalytic water splitting is a viable process for the generation of renewable fuels. Here it is reported for the first time that a trinuclear supramolecular Ru(bda) (bda: 2,2′‐bipyridine‐6,6′‐dicarboxylate) catalyst, anchored on multi‐walled carbon nanotubes and subsequently immobilized on glassy carbon electrodes, shows outstanding performance in heterogeneous water oxidation. Activation of the catalyst on anodes by repetitive cyclic voltammetry (CV) scans results in a catalytic current density of 186 mA cm−2 at a potential of 1.45 V versus NHE. The activated catalyst performs water oxidation at an onset overpotential of 330 mV. The remarkably high stability of the hybrid anode is demonstrated by X‐ray absorption spectroscopy and electrochemically, revealing the absence of any degradation after 1.8 million turnovers. Foot of the wave analysis of CV data of activated electrodes with different concentrations of catalyst indicates a monomolecular water nucleophilic attack mechanism with an apparent rate constant of TOFmax (turnover frequency) of 3200 s−1.

  @article{Schindler_2020, abstract = {Catalytic water splitting is a viable process for the generation of renewable fuels. Here it is reported for the first time that a trinuclear supramolecular Ru(bda) (bda: 2,2′‐bipyridine‐6,6′‐dicarboxylate) catalyst, anchored on multi‐walled carbon nanotubes and subsequently immobilized on glassy carbon electrodes, shows outstanding performance in heterogeneous water oxidation. Activation of the catalyst on anodes by repetitive cyclic voltammetry (CV) scans results in a catalytic current density of 186 mA cm−2 at a potential of 1.45 V versus NHE. The activated catalyst performs water oxidation at an onset overpotential of 330 mV. The remarkably high stability of the hybrid anode is demonstrated by X‐ray absorption spectroscopy and electrochemically, revealing the absence of any degradation after 1.8 million turnovers. Foot of the wave analysis of CV data of activated electrodes with different concentrations of catalyst indicates a monomolecular water nucleophilic attack mechanism with an apparent rate constant of TOFmax (turnover frequency) of 3200 s−1.}, author = {Schindler, Dorothee and Gil-Sepulcre, Marcos and Lindner, Joachim O. and Stepanenko, Vladimir and Moonshiram, Dooshaye and Llobet, Antoni and Würthner, Frank}, journal = {Adv. Energy Mater.}, keywords = {myown}, month = 10, number = 43, pages = 2002329, publisher = {Wiley}, title = {Efficient Electrochemical Water Oxidation by a Trinuclear Ru(bda) Macrocycle Immobilized on Multi-Walled Carbon Nanotube Electrodes}, volume = 10, year = 2020 }

  %0 Journal Article %1 Schindler_2020 %A Schindler, Dorothee %A Gil-Sepulcre, Marcos %A Lindner, Joachim O. %A Stepanenko, Vladimir %A Moonshiram, Dooshaye %A Llobet, Antoni %A Würthner, Frank %D 2020 %I Wiley %J Adv. Energy Mater. %N 43 %P 2002329 %R 10.1002/aenm.202002329 %T Efficient Electrochemical Water Oxidation by a Trinuclear Ru(bda) Macrocycle Immobilized on Multi-Walled Carbon Nanotube Electrodes %U https://doi.org/10.1002%2Faenm.202002329 %V 10 %X Catalytic water splitting is a viable process for the generation of renewable fuels. Here it is reported for the first time that a trinuclear supramolecular Ru(bda) (bda: 2,2′‐bipyridine‐6,6′‐dicarboxylate) catalyst, anchored on multi‐walled carbon nanotubes and subsequently immobilized on glassy carbon electrodes, shows outstanding performance in heterogeneous water oxidation. Activation of the catalyst on anodes by repetitive cyclic voltammetry (CV) scans results in a catalytic current density of 186 mA cm−2 at a potential of 1.45 V versus NHE. The activated catalyst performs water oxidation at an onset overpotential of 330 mV. The remarkably high stability of the hybrid anode is demonstrated by X‐ray absorption spectroscopy and electrochemically, revealing the absence of any degradation after 1.8 million turnovers. Foot of the wave analysis of CV data of activated electrodes with different concentrations of catalyst indicates a monomolecular water nucleophilic attack mechanism with an apparent rate constant of TOFmax (turnover frequency) of 3200 s−1.
• A Periodic System of Supramolecular Elements. Schmidt, Hans-Werner; Würthner, Frank. In Angew. Chem. Int. Ed., 59(23), pp. 8766–8775. 2020.
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  @article{Schmidt_2020, author = {Schmidt, Hans-Werner and Würthner, Frank}, journal = {Angew. Chem. Int. Ed.}, keywords = {myown}, month = {02}, number = 23, pages = {8766–8775}, publisher = {Wiley}, title = {A Periodic System of Supramolecular Elements}, volume = 59, year = 2020 }

  %0 Journal Article %1 Schmidt_2020 %A Schmidt, Hans-Werner %A Würthner, Frank %D 2020 %I Wiley %J Angew. Chem. Int. Ed. %N 23 %P 8766--8775 %R 10.1002/anie.201915643 %T A Periodic System of Supramolecular Elements %U https://doi.org/10.1002%2Fanie.201915643 %V 59
• NIR-emitting squaraine J-aggregate nanosheets. Shen, Chia-An; Würthner, Frank. In Chem. Commun., 56(68), pp. 9878–9881. 2020.
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  Click chemistry and Yamamoto coupling afforded an S-shaped π-scaffold composed of two directly connected dicyanomethylene-substituted squaraine dyes. This bis(squaraine) self-assembles into nanosheets in a cooperative self-assembly process, affording an absorption maximum at 886 nm and a fluorescence peak at 904 nm due to strong J-type exciton coupling.

  @article{D0CC03686B, abstract = {Click chemistry and Yamamoto coupling afforded an S-shaped π-scaffold composed of two directly connected dicyanomethylene-substituted squaraine dyes. This bis(squaraine) self-assembles into nanosheets in a cooperative self-assembly process{,} affording an absorption maximum at 886 nm and a fluorescence peak at 904 nm due to strong J-type exciton coupling.}, author = {Shen, Chia-An and Würthner, Frank}, journal = {Chem. Commun.}, keywords = {myown}, number = 68, pages = {9878-9881}, publisher = {The Royal Society of Chemistry}, title = {NIR-emitting squaraine J-aggregate nanosheets}, volume = 56, year = 2020 }

  %0 Journal Article %1 D0CC03686B %A Shen, Chia-An %A Würthner, Frank %D 2020 %I The Royal Society of Chemistry %J Chem. Commun. %N 68 %P 9878-9881 %R 10.1039/D0CC03686B %T NIR-emitting squaraine J-aggregate nanosheets %U http://dx.doi.org/10.1039/D0CC03686B %V 56 %X Click chemistry and Yamamoto coupling afforded an S-shaped π-scaffold composed of two directly connected dicyanomethylene-substituted squaraine dyes. This bis(squaraine) self-assembles into nanosheets in a cooperative self-assembly process, affording an absorption maximum at 886 nm and a fluorescence peak at 904 nm due to strong J-type exciton coupling.
• Nanoscale Columnar Bundles Based on Multistranded Core-Shell Liquid Crystals of Perylene Bisimide J-Aggregate Donor-Acceptor Dyads for Photoconductivity Devices with Enhanced Performance Through Macroscopic Alignment. Hecht, Markus; Schlossarek, Tim; Ghosh, Samrat; Tsutsui, Yusuke; Schmiedel, Alexander; Holzapfel, Marco; Stolte, Matthias; Lambert, Christoph; Seki, Shu; Lehmann, Matthias; Würthner, Frank. In Appl. Nano Mater., 3(10), pp. 10234–10245. 2020.
  • [ Abstract ]
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  Donor–acceptor dyads consisting of perylene bisimide (PBI) and trialkoxyphenyl–oligothiophene (TAPOT) units are reported that self-assemble into helical four-, six-, and seven-stranded hydrogen-bonded supramolecular polymers in solution and the columnar liquid-crystalline state. It is shown that the number of closely stacked and J-coupled PBI strands can be controlled by the incremental extension of the TAPOT wedge units in the bay position and the thereby tailored steric demand. Narcissistic self-sorting of TAPOT donor and PBI acceptor subunits facilitates the formation of core–shell structures creating individual percolation pathways for one-dimensional (1D) transport of photogenerated charge carriers. Macroscopic alignment of the nanoscale columnar structures by solution shearing enables anisotropic photoconductivity. Thus, selective orientation of the 1D charge-transporting domains parallel and perpendicular to the electrodes gives rise to an up to 90-fold increased photoresponse depending on the alignment quality. The intrinsic charge-separation and -transport properties were investigated by femtosecond transient absorption spectroscopy and flash-photolysis time-resolved microwave conductivity. These studies reveal a rising propensity for charge separation and transport upon increasing the conjugation length of the TAPOT donor and thereby increasing the size of the individual percolation pathways. Contrasting observations for intrinsic and macroscopic photoconductivities demonstrate the importance of processability in device performance.

  @article{Hecht_2020, abstract = {Donor–acceptor dyads consisting of perylene bisimide (PBI) and trialkoxyphenyl–oligothiophene (TAPOT) units are reported that self-assemble into helical four-, six-, and seven-stranded hydrogen-bonded supramolecular polymers in solution and the columnar liquid-crystalline state. It is shown that the number of closely stacked and J-coupled PBI strands can be controlled by the incremental extension of the TAPOT wedge units in the bay position and the thereby tailored steric demand. Narcissistic self-sorting of TAPOT donor and PBI acceptor subunits facilitates the formation of core–shell structures creating individual percolation pathways for one-dimensional (1D) transport of photogenerated charge carriers. Macroscopic alignment of the nanoscale columnar structures by solution shearing enables anisotropic photoconductivity. Thus, selective orientation of the 1D charge-transporting domains parallel and perpendicular to the electrodes gives rise to an up to 90-fold increased photoresponse depending on the alignment quality. The intrinsic charge-separation and -transport properties were investigated by femtosecond transient absorption spectroscopy and flash-photolysis time-resolved microwave conductivity. These studies reveal a rising propensity for charge separation and transport upon increasing the conjugation length of the TAPOT donor and thereby increasing the size of the individual percolation pathways. Contrasting observations for intrinsic and macroscopic photoconductivities demonstrate the importance of processability in device performance.}, author = {Hecht, Markus and Schlossarek, Tim and Ghosh, Samrat and Tsutsui, Yusuke and Schmiedel, Alexander and Holzapfel, Marco and Stolte, Matthias and Lambert, Christoph and Seki, Shu and Lehmann, Matthias and Würthner, Frank}, journal = {Appl. Nano Mater.}, keywords = {myown}, month = {09}, number = 10, pages = {10234–10245}, publisher = {American Chemical Society (ACS)}, title = {Nanoscale Columnar Bundles Based on Multistranded Core-Shell Liquid Crystals of Perylene Bisimide J-Aggregate Donor-Acceptor Dyads for Photoconductivity Devices with Enhanced Performance Through Macroscopic Alignment}, volume = 3, year = 2020 }

  %0 Journal Article %1 Hecht_2020 %A Hecht, Markus %A Schlossarek, Tim %A Ghosh, Samrat %A Tsutsui, Yusuke %A Schmiedel, Alexander %A Holzapfel, Marco %A Stolte, Matthias %A Lambert, Christoph %A Seki, Shu %A Lehmann, Matthias %A Würthner, Frank %D 2020 %I American Chemical Society (ACS) %J Appl. Nano Mater. %N 10 %P 10234--10245 %R 10.1021/acsanm.0c02189 %T Nanoscale Columnar Bundles Based on Multistranded Core-Shell Liquid Crystals of Perylene Bisimide J-Aggregate Donor-Acceptor Dyads for Photoconductivity Devices with Enhanced Performance Through Macroscopic Alignment %U https://doi.org/10.1021%2Facsanm.0c02189 %V 3 %X Donor–acceptor dyads consisting of perylene bisimide (PBI) and trialkoxyphenyl–oligothiophene (TAPOT) units are reported that self-assemble into helical four-, six-, and seven-stranded hydrogen-bonded supramolecular polymers in solution and the columnar liquid-crystalline state. It is shown that the number of closely stacked and J-coupled PBI strands can be controlled by the incremental extension of the TAPOT wedge units in the bay position and the thereby tailored steric demand. Narcissistic self-sorting of TAPOT donor and PBI acceptor subunits facilitates the formation of core–shell structures creating individual percolation pathways for one-dimensional (1D) transport of photogenerated charge carriers. Macroscopic alignment of the nanoscale columnar structures by solution shearing enables anisotropic photoconductivity. Thus, selective orientation of the 1D charge-transporting domains parallel and perpendicular to the electrodes gives rise to an up to 90-fold increased photoresponse depending on the alignment quality. The intrinsic charge-separation and -transport properties were investigated by femtosecond transient absorption spectroscopy and flash-photolysis time-resolved microwave conductivity. These studies reveal a rising propensity for charge separation and transport upon increasing the conjugation length of the TAPOT donor and thereby increasing the size of the individual percolation pathways. Contrasting observations for intrinsic and macroscopic photoconductivities demonstrate the importance of processability in device performance.
• Exciton Migration in Multistranded Perylene Bisimide J-Aggregates. Rehhagen, Chris; Stolte, Matthias; Herbst, Stefanie; Hecht, Markus; Lochbrunner, Stefan; Würthner, Frank; Fennel, Franziska. In J. Phys. Chem. Lett., 11(16), pp. 6612–6617. 2020.
  • [ Abstract ]
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  Exciton migration in self-assembled supramolecular ensembles of dye molecules is controlled by the electronic coupling between adjacent sites, the delocalization of the excitation and thereby by the packing arrangement. Here, we put emphasis on the packing structure and analyze the exciton migration in two perylene bisimide-based J-aggregates composed of almost identical molecular building blocks but forming double-strand versus quadruple-strand slip-stacked supramolecular architectures. Analyzing ultrafast transient absorption spectra in dependence on the exciton density by a kinetic model for exciton–exciton annihilation based on incoherent transfer demonstrates that the migration is quasi one-dimensional. The migration distance is enhanced by a beneficial geometrical structure. We find a factor of more than two between the diffusion lengths of 188 and 77 nm for the double- and quadruple-stranded system. The supramolecular design efficiently influences the exciton mobility and minor structural changes have a pronounced influence on functional properties of dye aggregates.

  @article{Rehhagen_2020, abstract = {Exciton migration in self-assembled supramolecular ensembles of dye molecules is controlled by the electronic coupling between adjacent sites, the delocalization of the excitation and thereby by the packing arrangement. Here, we put emphasis on the packing structure and analyze the exciton migration in two perylene bisimide-based J-aggregates composed of almost identical molecular building blocks but forming double-strand versus quadruple-strand slip-stacked supramolecular architectures. Analyzing ultrafast transient absorption spectra in dependence on the exciton density by a kinetic model for exciton–exciton annihilation based on incoherent transfer demonstrates that the migration is quasi one-dimensional. The migration distance is enhanced by a beneficial geometrical structure. We find a factor of more than two between the diffusion lengths of 188 and 77 nm for the double- and quadruple-stranded system. The supramolecular design efficiently influences the exciton mobility and minor structural changes have a pronounced influence on functional properties of dye aggregates.}, author = {Rehhagen, Chris and Stolte, Matthias and Herbst, Stefanie and Hecht, Markus and Lochbrunner, Stefan and Würthner, Frank and Fennel, Franziska}, journal = {J. Phys. Chem. Lett.}, keywords = {myown}, month = {07}, number = 16, pages = {6612–6617}, publisher = {American Chemical Society ({ACS})}, title = {Exciton Migration in Multistranded Perylene Bisimide J-Aggregates}, volume = 11, year = 2020 }

  %0 Journal Article %1 Rehhagen_2020 %A Rehhagen, Chris %A Stolte, Matthias %A Herbst, Stefanie %A Hecht, Markus %A Lochbrunner, Stefan %A Würthner, Frank %A Fennel, Franziska %D 2020 %I American Chemical Society (ACS) %J J. Phys. Chem. Lett. %N 16 %P 6612--6617 %R 10.1021/acs.jpclett.0c01669 %T Exciton Migration in Multistranded Perylene Bisimide J-Aggregates %U https://doi.org/10.1021%2Facs.jpclett.0c01669 %V 11 %X Exciton migration in self-assembled supramolecular ensembles of dye molecules is controlled by the electronic coupling between adjacent sites, the delocalization of the excitation and thereby by the packing arrangement. Here, we put emphasis on the packing structure and analyze the exciton migration in two perylene bisimide-based J-aggregates composed of almost identical molecular building blocks but forming double-strand versus quadruple-strand slip-stacked supramolecular architectures. Analyzing ultrafast transient absorption spectra in dependence on the exciton density by a kinetic model for exciton–exciton annihilation based on incoherent transfer demonstrates that the migration is quasi one-dimensional. The migration distance is enhanced by a beneficial geometrical structure. We find a factor of more than two between the diffusion lengths of 188 and 77 nm for the double- and quadruple-stranded system. The supramolecular design efficiently influences the exciton mobility and minor structural changes have a pronounced influence on functional properties of dye aggregates.
• NIR-Absorbing pi-Extended Azulene: Non-Alternant Isomer of Terrylene Bisimide. Pigulski, Bartlomiej; Shoyama, Kazutaka; Würthner, Frank. In Angew. Chem. Int. Ed. 2020.
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  The first planar π‐extended azulene that retains aromaticity of odd‐membered rings was synthesized by [3+3] peri‐annulation of two naphthalene imides at both long‐edge sides of azulene. Using bromination and subsequent nucleophilic substitution by methoxide and morpholine, selective functionalization of the π‐extended azulene was achieved. Whilst these new azulenes can be regarded as isomers of terrylene bisimide they exhibit entirely different properties, which include very narrow optical and electrochemical gaps. DFT, TD‐DFT, as well as nucleus‐independent chemical shift calculations were applied to explain the structural and functional properties of these new π scaffolds. Furthermore, X‐ray crystallography confirmed the planarity of the reported π‐scaffolds and aromaticity of their azulene moiety.

  @article{Pigulski_2020, abstract = {The first planar π‐extended azulene that retains aromaticity of odd‐membered rings was synthesized by [3+3] peri‐annulation of two naphthalene imides at both long‐edge sides of azulene. Using bromination and subsequent nucleophilic substitution by methoxide and morpholine, selective functionalization of the π‐extended azulene was achieved. Whilst these new azulenes can be regarded as isomers of terrylene bisimide they exhibit entirely different properties, which include very narrow optical and electrochemical gaps. DFT, TD‐DFT, as well as nucleus‐independent chemical shift calculations were applied to explain the structural and functional properties of these new π scaffolds. Furthermore, X‐ray crystallography confirmed the planarity of the reported π‐scaffolds and aromaticity of their azulene moiety.}, author = {Pigulski, Bartlomiej and Shoyama, Kazutaka and Würthner, Frank}, journal = {Angew. Chem. Int. Ed.}, keywords = {myown}, month = {06}, publisher = {Wiley}, title = {NIR-Absorbing pi-Extended Azulene: Non-Alternant Isomer of Terrylene Bisimide}, year = 2020 }

  %0 Journal Article %1 Pigulski_2020 %A Pigulski, Bartlomiej %A Shoyama, Kazutaka %A Würthner, Frank %D 2020 %I Wiley %J Angew. Chem. Int. Ed. %R 10.1002/anie.202005376 %T NIR-Absorbing pi-Extended Azulene: Non-Alternant Isomer of Terrylene Bisimide %U https://doi.org/10.1002%2Fanie.202005376 %X The first planar π‐extended azulene that retains aromaticity of odd‐membered rings was synthesized by [3+3] peri‐annulation of two naphthalene imides at both long‐edge sides of azulene. Using bromination and subsequent nucleophilic substitution by methoxide and morpholine, selective functionalization of the π‐extended azulene was achieved. Whilst these new azulenes can be regarded as isomers of terrylene bisimide they exhibit entirely different properties, which include very narrow optical and electrochemical gaps. DFT, TD‐DFT, as well as nucleus‐independent chemical shift calculations were applied to explain the structural and functional properties of these new π scaffolds. Furthermore, X‐ray crystallography confirmed the planarity of the reported π‐scaffolds and aromaticity of their azulene moiety.
• Self-assembled Möbius strips with controlled helicity. Ouyang, Guanghui; Ji, Lukang; Jiang, Yuqian; Würthner, Frank; Liu, Minghua. In Nat. Commun., 11(1). 2020.
  • [ Abstract ]
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  Different from molecular level topology, the development of supramolecular topology has been limited due to a lack of reliable synthetic methods. Here we describe a supramolecular strategy of accessing Möbius strip, a fascinating topological object featured with only a single edge and single side. Through bending and cyclization of twisted nanofibers self-assembled from chiral glutamate amphiphiles, supramolecular nano-toroids with various twist numbers were obtained. Electron microscopic techniques could clearly identify the formation of Möbius strips when twist numbers on the toroidal fibers are odd ones. Spectroscopic and morphological analysis indicates that the helicity of the Möbius strips and nano-toroids stems from the molecular chirality of glutamate molecules. Therefore, M- and P-helical Möbius strips could be formed from L- and D-amphiphiles, respectively. Our experimental results and theoretical simulations may advance the prospect of creating chiral topologically complex structures via supramolecular approach.

  @article{Ouyang_2020, abstract = {Different from molecular level topology, the development of supramolecular topology has been limited due to a lack of reliable synthetic methods. Here we describe a supramolecular strategy of accessing Möbius strip, a fascinating topological object featured with only a single edge and single side. Through bending and cyclization of twisted nanofibers self-assembled from chiral glutamate amphiphiles, supramolecular nano-toroids with various twist numbers were obtained. Electron microscopic techniques could clearly identify the formation of Möbius strips when twist numbers on the toroidal fibers are odd ones. Spectroscopic and morphological analysis indicates that the helicity of the Möbius strips and nano-toroids stems from the molecular chirality of glutamate molecules. Therefore, M- and P-helical Möbius strips could be formed from L- and D-amphiphiles, respectively. Our experimental results and theoretical simulations may advance the prospect of creating chiral topologically complex structures via supramolecular approach.}, author = {Ouyang, Guanghui and Ji, Lukang and Jiang, Yuqian and Würthner, Frank and Liu, Minghua}, journal = {Nat. Commun.}, keywords = {myown}, month = 11, number = 1, publisher = {Springer Science and Business Media {LLC}}, title = {Self-assembled Möbius strips with controlled helicity}, volume = 11, year = 2020 }

  %0 Journal Article %1 Ouyang_2020 %A Ouyang, Guanghui %A Ji, Lukang %A Jiang, Yuqian %A Würthner, Frank %A Liu, Minghua %D 2020 %I Springer Science and Business Media LLC %J Nat. Commun. %N 1 %R 10.1038/s41467-020-19683-z %T Self-assembled Möbius strips with controlled helicity %U https://doi.org/10.1038%2Fs41467-020-19683-z %V 11 %X Different from molecular level topology, the development of supramolecular topology has been limited due to a lack of reliable synthetic methods. Here we describe a supramolecular strategy of accessing Möbius strip, a fascinating topological object featured with only a single edge and single side. Through bending and cyclization of twisted nanofibers self-assembled from chiral glutamate amphiphiles, supramolecular nano-toroids with various twist numbers were obtained. Electron microscopic techniques could clearly identify the formation of Möbius strips when twist numbers on the toroidal fibers are odd ones. Spectroscopic and morphological analysis indicates that the helicity of the Möbius strips and nano-toroids stems from the molecular chirality of glutamate molecules. Therefore, M- and P-helical Möbius strips could be formed from L- and D-amphiphiles, respectively. Our experimental results and theoretical simulations may advance the prospect of creating chiral topologically complex structures via supramolecular approach.

• Supramolecular Polymorphism in One-Dimensional Self-Assembly by Kinetic Pathway Control. Wehner, Marius; Röhr, Merle Insa Silja; Bühler, Michael; Stepanenko, Vladimir; Wagner, Wolfgang; Würthner, Frank. In J. Am. Chem. Soc., 141(14), pp. 6092–6107. 2019.
  • [ Abstract ]
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  Controlling polymorphism in molecular solids is of great interest since the properties and performances of molecular materials depend on the molecules’ mutual packing arrangements. Herein, we describe a perylene bisimide (PBI) organogelator molecule PBI-4 that self-assembles into three different one-dimensional supramolecular polymorphs (Agg 1–3) in the same solvent and at the same concentration at room temperature. The three supramolecular polymorphs were characterized by UV/vis, CD, fluorescence and IR spectroscopy, atomic force microscopy (AFM), and theoretical calculations, revealing that their packing arrangements are governed by distinct π–π-stacking modes and unique hydrogen-bonding patterns. Nudged elastic band (NEB) calculations for the nucleation processes toward Agg 2 and Agg 3 indicate that nucleation starts from a central kinetically trapped state Agg 1 and involves the reorganization of Agg 1 dimers. Time-, concentration-, and temperature-dependent UV/vis experiments provided insights into the thermodynamic stability of the supramolecular polymorphs of PBI-4 and the kinetics for their interconversion. On the basis of this information the production of a certain polymorph could be accomplished either physically by ultrasonication or chemically by seeding. This work contributes to the understanding of polymorphism at the lowest level of hierarchy that is the generation of self-assembled 1D aggregate structures.

  @article{Wehner_2019, abstract = {Controlling polymorphism in molecular solids is of great interest since the properties and performances of molecular materials depend on the molecules’ mutual packing arrangements. Herein, we describe a perylene bisimide (PBI) organogelator molecule PBI-4 that self-assembles into three different one-dimensional supramolecular polymorphs (Agg 1–3) in the same solvent and at the same concentration at room temperature. The three supramolecular polymorphs were characterized by UV/vis, CD, fluorescence and IR spectroscopy, atomic force microscopy (AFM), and theoretical calculations, revealing that their packing arrangements are governed by distinct π–π-stacking modes and unique hydrogen-bonding patterns. Nudged elastic band (NEB) calculations for the nucleation processes toward Agg 2 and Agg 3 indicate that nucleation starts from a central kinetically trapped state Agg 1 and involves the reorganization of Agg 1 dimers. Time-, concentration-, and temperature-dependent UV/vis experiments provided insights into the thermodynamic stability of the supramolecular polymorphs of PBI-4 and the kinetics for their interconversion. On the basis of this information the production of a certain polymorph could be accomplished either physically by ultrasonication or chemically by seeding. This work contributes to the understanding of polymorphism at the lowest level of hierarchy that is the generation of self-assembled 1D aggregate structures.}, author = {Wehner, Marius and Röhr, Merle Insa Silja and Bühler, Michael and Stepanenko, Vladimir and Wagner, Wolfgang and Würthner, Frank}, journal = {J. Am. Chem. Soc.}, keywords = {organic}, month = {03}, number = 14, pages = {6092–6107}, publisher = {American Chemical Society ({ACS})}, title = {Supramolecular Polymorphism in One-Dimensional Self-Assembly by Kinetic Pathway Control}, volume = 141, year = 2019 }

  %0 Journal Article %1 Wehner_2019 %A Wehner, Marius %A Röhr, Merle Insa Silja %A Bühler, Michael %A Stepanenko, Vladimir %A Wagner, Wolfgang %A Würthner, Frank %D 2019 %I American Chemical Society (ACS) %J J. Am. Chem. Soc. %N 14 %P 6092--6107 %R 10.1021/jacs.9b02046 %T Supramolecular Polymorphism in One-Dimensional Self-Assembly by Kinetic Pathway Control %U https://doi.org/10.1021%2Fjacs.9b02046 %V 141 %X Controlling polymorphism in molecular solids is of great interest since the properties and performances of molecular materials depend on the molecules’ mutual packing arrangements. Herein, we describe a perylene bisimide (PBI) organogelator molecule PBI-4 that self-assembles into three different one-dimensional supramolecular polymorphs (Agg 1–3) in the same solvent and at the same concentration at room temperature. The three supramolecular polymorphs were characterized by UV/vis, CD, fluorescence and IR spectroscopy, atomic force microscopy (AFM), and theoretical calculations, revealing that their packing arrangements are governed by distinct π–π-stacking modes and unique hydrogen-bonding patterns. Nudged elastic band (NEB) calculations for the nucleation processes toward Agg 2 and Agg 3 indicate that nucleation starts from a central kinetically trapped state Agg 1 and involves the reorganization of Agg 1 dimers. Time-, concentration-, and temperature-dependent UV/vis experiments provided insights into the thermodynamic stability of the supramolecular polymorphs of PBI-4 and the kinetics for their interconversion. On the basis of this information the production of a certain polymorph could be accomplished either physically by ultrasonication or chemically by seeding. This work contributes to the understanding of polymorphism at the lowest level of hierarchy that is the generation of self-assembled 1D aggregate structures.
• fs–ps Exciton dynamics in a stretched tetraphenylsquaraine polymer. Schreck, Maximilian H.; Breitschwerdt, Lena; Marciniak, Henning; Holzapfel, Marco; Schmidt, David; Würthner, Frank; Lambert, Christoph. In Phys. Chem. Chem. Phys., 21(28), pp. 15346–15355. 2019.
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  A tetraphenylsquaraine was synthesized whose structure was elucidated by single crystal X-ray structure analysis. Unlike all known indolenine squaraines, the tetraphenylsquaraine shows an unusual nonplanar structure with the four phenyl groups pointing away from the squaric acid core in order to avoid steric congestion. This tetraphenylsquaraine was polymerized by a Yamamoto coupling to form a conjugated polymer with Xn = 38. The absorption spectra of this polymer are red-shifted compared to that of the monomer and show a J-type absorption band due to exciton coupling. Transient absorption spectra with fs-time resolution display a strong ground state bleaching signal with a peak on the red side rising concurrently with the decay of a peak on the blue side of an isosbestic point at 12 000 cm−1. This behavior is caused by energy transfer between two slightly different sections of the polymer with time constants of 0.3 and 2.6 ps. According to semiempirical calculations these different sections are stretched and slightly bent conformations of the polymer strand. Power dependent transient absorption measurements indicate exciton annihilation which also proves the excitons to be very mobile.

  @article{C9CP02900A, abstract = {A tetraphenylsquaraine was synthesized whose structure was elucidated by single crystal X-ray structure analysis. Unlike all known indolenine squaraines{,} the tetraphenylsquaraine shows an unusual nonplanar structure with the four phenyl groups pointing away from the squaric acid core in order to avoid steric congestion. This tetraphenylsquaraine was polymerized by a Yamamoto coupling to form a conjugated polymer with Xn = 38. The absorption spectra of this polymer are red-shifted compared to that of the monomer and show a J-type absorption band due to exciton coupling. Transient absorption spectra with fs-time resolution display a strong ground state bleaching signal with a peak on the red side rising concurrently with the decay of a peak on the blue side of an isosbestic point at 12 000 cm−1. This behavior is caused by energy transfer between two slightly different sections of the polymer with time constants of 0.3 and 2.6 ps. According to semiempirical calculations these different sections are stretched and slightly bent conformations of the polymer strand. Power dependent transient absorption measurements indicate exciton annihilation which also proves the excitons to be very mobile.}, author = {Schreck, Maximilian H. and Breitschwerdt, Lena and Marciniak, Henning and Holzapfel, Marco and Schmidt, David and Würthner, Frank and Lambert, Christoph}, journal = {Phys. Chem. Chem. Phys.}, keywords = {myown}, number = 28, pages = {15346-15355}, publisher = {The Royal Society of Chemistry}, title = {fs–ps Exciton dynamics in a stretched tetraphenylsquaraine polymer}, volume = 21, year = 2019 }

  %0 Journal Article %1 C9CP02900A %A Schreck, Maximilian H. %A Breitschwerdt, Lena %A Marciniak, Henning %A Holzapfel, Marco %A Schmidt, David %A Würthner, Frank %A Lambert, Christoph %D 2019 %I The Royal Society of Chemistry %J Phys. Chem. Chem. Phys. %N 28 %P 15346-15355 %R 10.1039/C9CP02900A %T fs–ps Exciton dynamics in a stretched tetraphenylsquaraine polymer %U http://dx.doi.org/10.1039/C9CP02900A %V 21 %X A tetraphenylsquaraine was synthesized whose structure was elucidated by single crystal X-ray structure analysis. Unlike all known indolenine squaraines, the tetraphenylsquaraine shows an unusual nonplanar structure with the four phenyl groups pointing away from the squaric acid core in order to avoid steric congestion. This tetraphenylsquaraine was polymerized by a Yamamoto coupling to form a conjugated polymer with Xn = 38. The absorption spectra of this polymer are red-shifted compared to that of the monomer and show a J-type absorption band due to exciton coupling. Transient absorption spectra with fs-time resolution display a strong ground state bleaching signal with a peak on the red side rising concurrently with the decay of a peak on the blue side of an isosbestic point at 12 000 cm−1. This behavior is caused by energy transfer between two slightly different sections of the polymer with time constants of 0.3 and 2.6 ps. According to semiempirical calculations these different sections are stretched and slightly bent conformations of the polymer strand. Power dependent transient absorption measurements indicate exciton annihilation which also proves the excitons to be very mobile.
• Guest-mediated chirality transfer in the host–guest complexes of an atropisomeric perylene bisimide cyclophane host. Sapotta, Meike; Spenst, Peter; Saha-Möller, Chantu; Würthner, Frank. In Org. Chem. Front., 6, pp. 892–899. 2019.
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  The dynamic equilibrium of stereoisomers of a cyclophane, which is comprised of two atropisomeric perylene bisimide (PBI) subunits, and its host–guest binding with an achiral and a series of chiral guests have been studied. Temperature-dependent 1H NMR spectroscopic studies have shown that at higher temperature all three stereoisomers ((M,M) and (P,P) enantiomers and (M,P)/(P,M) mesomers) of the cyclophane are in a dynamic equilibrium as only one set of proton signals was observed. However, at a lower temperature (260 K) two sets of signals in a ratio of 2 : 1, instead of the theoretically expected 1 : 1 ratio, were observed for the diastereomers (M,M)/(P,P) and (M,P)/(P,M) of the cyclophane presumably due to the chiral recognition of the enantiomeric (M,M)/(P,P) conformers. The 1H NMR studies further revealed that the achiral guest perylene mostly selects the (M,M)/(P,P) enantiomeric pair of the host for encapsulation. The induction of chirality in the host–guest complexes of the cyclophane with chiral guests has been investigated by circular dichroism (CD) spectroscopy. A distinct CD effect was observed upon addition of chiral guests to the solution of a racemic cyclophane host, indicating a pronounced preference of the chiral guests for one of the two homochiral stereoisomers, (M,M) and (P,P), for encapsulation. Kinetic studies by time-dependent NMR spectroscopy did not lead to conclusive results to assign the recognition process of chiral guests to either the induced fit or the conformational selection model.

  @article{sapotta2019guestmediated, abstract = {The dynamic equilibrium of stereoisomers of a cyclophane, which is comprised of two atropisomeric perylene bisimide (PBI) subunits, and its host–guest binding with an achiral and a series of chiral guests have been studied. Temperature-dependent 1H NMR spectroscopic studies have shown that at higher temperature all three stereoisomers ((M,M) and (P,P) enantiomers and (M,P)/(P,M) mesomers) of the cyclophane are in a dynamic equilibrium as only one set of proton signals was observed. However, at a lower temperature (260 K) two sets of signals in a ratio of 2 : 1, instead of the theoretically expected 1 : 1 ratio, were observed for the diastereomers (M,M)/(P,P) and (M,P)/(P,M) of the cyclophane presumably due to the chiral recognition of the enantiomeric (M,M)/(P,P) conformers. The 1H NMR studies further revealed that the achiral guest perylene mostly selects the (M,M)/(P,P) enantiomeric pair of the host for encapsulation. The induction of chirality in the host–guest complexes of the cyclophane with chiral guests has been investigated by circular dichroism (CD) spectroscopy. A distinct CD effect was observed upon addition of chiral guests to the solution of a racemic cyclophane host, indicating a pronounced preference of the chiral guests for one of the two homochiral stereoisomers, (M,M) and (P,P), for encapsulation. Kinetic studies by time-dependent NMR spectroscopy did not lead to conclusive results to assign the recognition process of chiral guests to either the induced fit or the conformational selection model.}, author = {Sapotta, Meike and Spenst, Peter and Saha-Möller, Chantu and Würthner, Frank}, journal = {Org. Chem. Front.}, keywords = {molecular}, month = {03}, pages = {892–899}, title = {Guest-mediated chirality transfer in the host–guest complexes of an atropisomeric perylene bisimide cyclophane host}, volume = 6, year = 2019 }

  %0 Journal Article %1 sapotta2019guestmediated %A Sapotta, Meike %A Spenst, Peter %A Saha-Möller, Chantu %A Würthner, Frank %D 2019 %J Org. Chem. Front. %P 892–899 %R 10.1039/c9qo00172g %T Guest-mediated chirality transfer in the host–guest complexes of an atropisomeric perylene bisimide cyclophane host %V 6 %X The dynamic equilibrium of stereoisomers of a cyclophane, which is comprised of two atropisomeric perylene bisimide (PBI) subunits, and its host–guest binding with an achiral and a series of chiral guests have been studied. Temperature-dependent 1H NMR spectroscopic studies have shown that at higher temperature all three stereoisomers ((M,M) and (P,P) enantiomers and (M,P)/(P,M) mesomers) of the cyclophane are in a dynamic equilibrium as only one set of proton signals was observed. However, at a lower temperature (260 K) two sets of signals in a ratio of 2 : 1, instead of the theoretically expected 1 : 1 ratio, were observed for the diastereomers (M,M)/(P,P) and (M,P)/(P,M) of the cyclophane presumably due to the chiral recognition of the enantiomeric (M,M)/(P,P) conformers. The 1H NMR studies further revealed that the achiral guest perylene mostly selects the (M,M)/(P,P) enantiomeric pair of the host for encapsulation. The induction of chirality in the host–guest complexes of the cyclophane with chiral guests has been investigated by circular dichroism (CD) spectroscopy. A distinct CD effect was observed upon addition of chiral guests to the solution of a racemic cyclophane host, indicating a pronounced preference of the chiral guests for one of the two homochiral stereoisomers, (M,M) and (P,P), for encapsulation. Kinetic studies by time-dependent NMR spectroscopy did not lead to conclusive results to assign the recognition process of chiral guests to either the induced fit or the conformational selection model.
• Self‐Assembly of Bowl‐Shaped Naphthalimide‐Annulated Corannulene. Renner, Rebecca; Stolte, Matthias; Würthner, Frank. In ChemistryOpen, 9(1), pp. 32–39. 2019.
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  The self‐assembly of a bowl‐shaped naphthalimide‐annulated corannulene of high solubility has been studied in a variety of solvents by NMR and UV/Vis spectroscopy. Evaluation by the anti‐cooperative K2‐K model revealed the formation of supramolecular dimers of outstanding thermodynamic stability. Further structural proof for the almost exclusive formation of dimers over extended aggregates is demonstrated by atomic force microscopy (AFM) and diffusion ordered spectroscopy (DOSY) measurements as well as by theoretical calculations. Thus, herein we present the first report of a supramolecular dimer of an annulated corannulene derivative in solution and discuss its extraordinarily high thermodynamic stability with association constants up to >106 M−1 in methylcyclohexane, which is comparable to the association constants given for planar phthalocyanine and perylene bisimide dyes.

  @article{noauthororeditor, abstract = {The self‐assembly of a bowl‐shaped naphthalimide‐annulated corannulene of high solubility has been studied in a variety of solvents by NMR and UV/Vis spectroscopy. Evaluation by the anti‐cooperative K2‐K model revealed the formation of supramolecular dimers of outstanding thermodynamic stability. Further structural proof for the almost exclusive formation of dimers over extended aggregates is demonstrated by atomic force microscopy (AFM) and diffusion ordered spectroscopy (DOSY) measurements as well as by theoretical calculations. Thus, herein we present the first report of a supramolecular dimer of an annulated corannulene derivative in solution and discuss its extraordinarily high thermodynamic stability with association constants up to >106 M−1 in methylcyclohexane, which is comparable to the association constants given for planar phthalocyanine and perylene bisimide dyes.}, author = {Renner, Rebecca and Stolte, Matthias and Würthner, Frank}, journal = {ChemistryOpen}, keywords = {myown}, month = {01}, number = 1, pages = {32-39}, title = {Self‐Assembly of Bowl‐Shaped Naphthalimide‐Annulated Corannulene}, volume = 9, year = 2019 }

  %0 Journal Article %1 noauthororeditor %A Renner, Rebecca %A Stolte, Matthias %A Würthner, Frank %D 2019 %J ChemistryOpen %N 1 %P 32-39 %R 10.1002/open.201900291 %T Self‐Assembly of Bowl‐Shaped Naphthalimide‐Annulated Corannulene %U https://onlinelibrary.wiley.com/doi/full/10.1002/open.201900291 %V 9 %X The self‐assembly of a bowl‐shaped naphthalimide‐annulated corannulene of high solubility has been studied in a variety of solvents by NMR and UV/Vis spectroscopy. Evaluation by the anti‐cooperative K2‐K model revealed the formation of supramolecular dimers of outstanding thermodynamic stability. Further structural proof for the almost exclusive formation of dimers over extended aggregates is demonstrated by atomic force microscopy (AFM) and diffusion ordered spectroscopy (DOSY) measurements as well as by theoretical calculations. Thus, herein we present the first report of a supramolecular dimer of an annulated corannulene derivative in solution and discuss its extraordinarily high thermodynamic stability with association constants up to >106 M−1 in methylcyclohexane, which is comparable to the association constants given for planar phthalocyanine and perylene bisimide dyes.
• A Self-Assembl ed Unit Comprising 12 Squaraine Dyes Built Up from TwoStar-ShapedHexasquara inyl-Benzene Molecules. Schreck, Maximilian H.; Röhr, Merle I. S.; Clark, Timothy; Stepanenko, Vladimir; Würthner, Frank; Lambert, Christoph. In Cemistry - A European Journal, 25, pp. 2831–2839. 2019.
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  We describe the aggregate formation and optical properties of astar-shaped hexaarylbenzene with six squar-aine chromophores (= hexasquarainyl benzene). Comprehen-sive concentration-dependence studies in acetone/CHCl3 mixtures reveala strong propensity to form discrete dimeric aggregates with ahighbinding constant in excess of 106 m@1.Inthis context, alarge hypsochromic shift of almost 2700 cm@1 was found in the absorption spectrum, indicating H-typeexciton coupling. The aggregate band is character-ised by avery small band width of only 560 cm@1,probably causedbyexchange narrowing. Both experimental and com-putational methods were used to elucidate the supramolec-ular aggregate structure, which is assumed to consistoftwo stacked hexasquarainyl benzene monomers.

  @article{schreck2019selfassembl, abstract = {We describe the aggregate formation and optical properties of astar-shaped hexaarylbenzene with six squar-aine chromophores (= hexasquarainyl benzene). Comprehen-sive concentration-dependence studies in acetone/CHCl3 mixtures reveala strong propensity to form discrete dimeric aggregates with ahighbinding constant in excess of 106 m@1.Inthis context, alarge hypsochromic shift of almost 2700 cm@1 was found in the absorption spectrum, indicating H-typeexciton coupling. The aggregate band is character-ised by avery small band width of only 560 cm@1,probably causedbyexchange narrowing. Both experimental and com-putational methods were used to elucidate the supramolec-ular aggregate structure, which is assumed to consistoftwo stacked hexasquarainyl benzene monomers.}, author = {Schreck, Maximilian H. and Röhr, Merle I. S. and Clark, Timothy and Stepanenko, Vladimir and Würthner, Frank and Lambert, Christoph}, journal = {Cemistry - A European Journal}, keywords = {molecular}, month = {03}, pages = {2831-2839}, title = {A Self-Assembl ed Unit Comprising 12 Squaraine Dyes Built Up from TwoStar-ShapedHexasquara inyl-Benzene Molecules}, volume = 25, year = 2019 }

  %0 Journal Article %1 schreck2019selfassembl %A Schreck, Maximilian H. %A Röhr, Merle I. S. %A Clark, Timothy %A Stepanenko, Vladimir %A Würthner, Frank %A Lambert, Christoph %D 2019 %J Cemistry - A European Journal %P 2831-2839 %R 10.1002/chem.201805685 %T A Self-Assembl ed Unit Comprising 12 Squaraine Dyes Built Up from TwoStar-ShapedHexasquara inyl-Benzene Molecules %V 25 %X We describe the aggregate formation and optical properties of astar-shaped hexaarylbenzene with six squar-aine chromophores (= hexasquarainyl benzene). Comprehen-sive concentration-dependence studies in acetone/CHCl3 mixtures reveala strong propensity to form discrete dimeric aggregates with ahighbinding constant in excess of 106 m@1.Inthis context, alarge hypsochromic shift of almost 2700 cm@1 was found in the absorption spectrum, indicating H-typeexciton coupling. The aggregate band is character-ised by avery small band width of only 560 cm@1,probably causedbyexchange narrowing. Both experimental and com-putational methods were used to elucidate the supramolec-ular aggregate structure, which is assumed to consistoftwo stacked hexasquarainyl benzene monomers.
• Anisotropic microfibres of a liquid-crystalline diketopyrrolopyrrole by self-assembly-assisted electrospinning. Hecht, Markus; Soberats, Bartolome; Zhu, Jian; Stepanenko, Vladimir; Agarwal, Seema; Greiner, Andreas; Würthner, Frank. In Nanoscale Horizons, 4, pp. 169–174. 2019.
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  Electrospinning is a well-established technique for the preparation of nanofibres from polymer solution or melt, however it is rarely applied for small molecules. Here we report a unique example of a liquid-crystalline (LC) diketopyrrolopyrrole (DPP) dye that was successfully used for electrospinning. Micrometric fibres with anisotropic alignment of DPP dye were produced by this process as shown by polarized optical microscopy and selected area electron diffraction. This newly designed DPP dye self-assembles in solution by hydrogen bonding and π–π-interactions and forms columnar LC phases in the bulk. X-ray scattering and polarized FT-IR studies in the LC state revealed a hierarchical arrangement of DPP molecules into columnar structures. The successful preparation of anisotropic microfibers by electrospinning is attributed to the hydrogen bond-directed supramolecular polymerization of the new DPP dye in solution and its LC properties.

  @article{hecht2018anisotropic, abstract = {Electrospinning is a well-established technique for the preparation of nanofibres from polymer solution or melt, however it is rarely applied for small molecules. Here we report a unique example of a liquid-crystalline (LC) diketopyrrolopyrrole (DPP) dye that was successfully used for electrospinning. Micrometric fibres with anisotropic alignment of DPP dye were produced by this process as shown by polarized optical microscopy and selected area electron diffraction. This newly designed DPP dye self-assembles in solution by hydrogen bonding and π–π-interactions and forms columnar LC phases in the bulk. X-ray scattering and polarized FT-IR studies in the LC state revealed a hierarchical arrangement of DPP molecules into columnar structures. The successful preparation of anisotropic microfibers by electrospinning is attributed to the hydrogen bond-directed supramolecular polymerization of the new DPP dye in solution and its LC properties.}, author = {Hecht, Markus and Soberats, Bartolome and Zhu, Jian and Stepanenko, Vladimir and Agarwal, Seema and Greiner, Andreas and Würthner, Frank}, journal = {Nanoscale Horizons}, keywords = {molecular}, month = {01}, pages = {169-174}, title = {Anisotropic microfibres of a liquid-crystalline diketopyrrolopyrrole by self-assembly-assisted electrospinning}, volume = 4, year = 2019 }

  %0 Journal Article %1 hecht2018anisotropic %A Hecht, Markus %A Soberats, Bartolome %A Zhu, Jian %A Stepanenko, Vladimir %A Agarwal, Seema %A Greiner, Andreas %A Würthner, Frank %D 2019 %J Nanoscale Horizons %P 169-174 %R 10.1039/C8NH00219C %T Anisotropic microfibres of a liquid-crystalline diketopyrrolopyrrole by self-assembly-assisted electrospinning %V 4 %X Electrospinning is a well-established technique for the preparation of nanofibres from polymer solution or melt, however it is rarely applied for small molecules. Here we report a unique example of a liquid-crystalline (LC) diketopyrrolopyrrole (DPP) dye that was successfully used for electrospinning. Micrometric fibres with anisotropic alignment of DPP dye were produced by this process as shown by polarized optical microscopy and selected area electron diffraction. This newly designed DPP dye self-assembles in solution by hydrogen bonding and π–π-interactions and forms columnar LC phases in the bulk. X-ray scattering and polarized FT-IR studies in the LC state revealed a hierarchical arrangement of DPP molecules into columnar structures. The successful preparation of anisotropic microfibers by electrospinning is attributed to the hydrogen bond-directed supramolecular polymerization of the new DPP dye in solution and its LC properties.
• The origin of the solvent dependence of fluorescence quantum yields in dipolar merocyanine dyes. Hoche, Joscha; Schulz, Alexander; Dietrich, Lysanne Monika; Humeniuk, Alexander; Stolte, Matthias; Schmidt, David; Brixner, Tobias; Würthner, Frank; Mitric, Roland. In Chem. Sci., 10(48), pp. 11013–11022. 2019.
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  Fluorophores with high quantum yields are desired for a variety of applications. Optimization of promising chromophores requires an understanding of the non-radiative decay channels that compete with the emission of photons. We synthesized a new derivative of the famous laser dye 4-dicyanomethylen-2-methyl-6-p-dimethylaminostyryl-4H-pyran (DCM), i.e., merocyanine 4-(dicyanomethylene)-2-tert-butyl-6-[3-(3-butyl-benzothiazol-2-ylidene)1-propenyl]-4H-pyran (DCBT). We measured fluorescence lifetimes and quantum yields in a variety of solvents and found a trend opposite to the energy gap law. This motivated a theoretical investigation into the possible non-radiative decay channels. We propose that a barrier to a conical intersection exists that is very sensitive to the solvent polarity. The conical intersection is characterized by a twisted geometry which allows a subsequent photoisomerization. Transient absorption measurements confirmed the formation of a photoisomer in unpolar solvents, while the measurements of fluorescence quantum yields at low temperature demonstrated the existence of an activation energy barrier.

  @article{C9SC05012D, abstract = {Fluorophores with high quantum yields are desired for a variety of applications. Optimization of promising chromophores requires an understanding of the non-radiative decay channels that compete with the emission of photons. We synthesized a new derivative of the famous laser dye 4-dicyanomethylen-2-methyl-6-p-dimethylaminostyryl-4H-pyran (DCM){,} i.e.{,} merocyanine 4-(dicyanomethylene)-2-tert-butyl-6-[3-(3-butyl-benzothiazol-2-ylidene)1-propenyl]-4H-pyran (DCBT). We measured fluorescence lifetimes and quantum yields in a variety of solvents and found a trend opposite to the energy gap law. This motivated a theoretical investigation into the possible non-radiative decay channels. We propose that a barrier to a conical intersection exists that is very sensitive to the solvent polarity. The conical intersection is characterized by a twisted geometry which allows a subsequent photoisomerization. Transient absorption measurements confirmed the formation of a photoisomer in unpolar solvents{,} while the measurements of fluorescence quantum yields at low temperature demonstrated the existence of an activation energy barrier.}, author = {Hoche, Joscha and Schulz, Alexander and Dietrich, Lysanne Monika and Humeniuk, Alexander and Stolte, Matthias and Schmidt, David and Brixner, Tobias and Würthner, Frank and Mitric, Roland}, journal = {Chem. Sci.}, keywords = {myown}, month = 12, number = 48, pages = {11013-11022}, publisher = {The Royal Society of Chemistry}, title = {The origin of the solvent dependence of fluorescence quantum yields in dipolar merocyanine dyes}, volume = 10, year = 2019 }

  %0 Journal Article %1 C9SC05012D %A Hoche, Joscha %A Schulz, Alexander %A Dietrich, Lysanne Monika %A Humeniuk, Alexander %A Stolte, Matthias %A Schmidt, David %A Brixner, Tobias %A Würthner, Frank %A Mitric, Roland %D 2019 %I The Royal Society of Chemistry %J Chem. Sci. %N 48 %P 11013-11022 %R 10.1039/C9SC05012D %T The origin of the solvent dependence of fluorescence quantum yields in dipolar merocyanine dyes %U http://dx.doi.org/10.1039/C9SC05012D %V 10 %X Fluorophores with high quantum yields are desired for a variety of applications. Optimization of promising chromophores requires an understanding of the non-radiative decay channels that compete with the emission of photons. We synthesized a new derivative of the famous laser dye 4-dicyanomethylen-2-methyl-6-p-dimethylaminostyryl-4H-pyran (DCM), i.e., merocyanine 4-(dicyanomethylene)-2-tert-butyl-6-[3-(3-butyl-benzothiazol-2-ylidene)1-propenyl]-4H-pyran (DCBT). We measured fluorescence lifetimes and quantum yields in a variety of solvents and found a trend opposite to the energy gap law. This motivated a theoretical investigation into the possible non-radiative decay channels. We propose that a barrier to a conical intersection exists that is very sensitive to the solvent polarity. The conical intersection is characterized by a twisted geometry which allows a subsequent photoisomerization. Transient absorption measurements confirmed the formation of a photoisomer in unpolar solvents, while the measurements of fluorescence quantum yields at low temperature demonstrated the existence of an activation energy barrier.
• Solvent-Modulated Charge-Transfer Resonance Enhancement in the Excimer State of a Bay-Substituted Perylene Bisimide Cyclophane. Kim, Woojae; Nowak-Król, Agnieszka; Hong, Yongseok; Schlosser, Felix; Würthner, Frank; Kim, Dongho. In J. Phys. Chem. Lett., 10(8), pp. 1919–1927. 2019.
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  Excimer, a configurational mixing between Frenkel exciton and charge-transfer resonance states, is typically regarded as a trap state that hinders desired energy or charge-transfer processes in artificial molecular assemblies. However, in recent days, the excimer has received much attention as a functional intermediate in the excited-state dynamics such as singlet fission or charge-separation processes. In this work, we show that the relative contribution to charge-transfer resonance of the excimer state in a bay-substituted perylene bisimide dimer cyclophane can be modulated by dielectric properties of the solvents employed. Solvent-dependent time-resolved fluorescence and absorption measurements reveal that an enhancement of charge-transfer resonance in the excimer state is reflected by incomplete symmetry-breaking charge-separation processes from the structurally relaxed excimer state by means of dipolar solvation processes in the high dielectric environment.

  @article{Kim_2019, abstract = {Excimer, a configurational mixing between Frenkel exciton and charge-transfer resonance states, is typically regarded as a trap state that hinders desired energy or charge-transfer processes in artificial molecular assemblies. However, in recent days, the excimer has received much attention as a functional intermediate in the excited-state dynamics such as singlet fission or charge-separation processes. In this work, we show that the relative contribution to charge-transfer resonance of the excimer state in a bay-substituted perylene bisimide dimer cyclophane can be modulated by dielectric properties of the solvents employed. Solvent-dependent time-resolved fluorescence and absorption measurements reveal that an enhancement of charge-transfer resonance in the excimer state is reflected by incomplete symmetry-breaking charge-separation processes from the structurally relaxed excimer state by means of dipolar solvation processes in the high dielectric environment.}, author = {Kim, Woojae and Nowak-Król, Agnieszka and Hong, Yongseok and Schlosser, Felix and Würthner, Frank and Kim, Dongho}, journal = {J. Phys. Chem. Lett.}, keywords = {organic}, month = {03}, number = 8, pages = {1919–1927}, publisher = {American Chemical Society (ACS)}, title = {Solvent-Modulated Charge-Transfer Resonance Enhancement in the Excimer State of a Bay-Substituted Perylene Bisimide Cyclophane}, volume = 10, year = 2019 }

  %0 Journal Article %1 Kim_2019 %A Kim, Woojae %A Nowak-Król, Agnieszka %A Hong, Yongseok %A Schlosser, Felix %A Würthner, Frank %A Kim, Dongho %D 2019 %I American Chemical Society (ACS) %J J. Phys. Chem. Lett. %N 8 %P 1919--1927 %R 10.1021/acs.jpclett.9b00357 %T Solvent-Modulated Charge-Transfer Resonance Enhancement in the Excimer State of a Bay-Substituted Perylene Bisimide Cyclophane %U https://doi.org/10.1021%2Facs.jpclett.9b00357 %V 10 %X Excimer, a configurational mixing between Frenkel exciton and charge-transfer resonance states, is typically regarded as a trap state that hinders desired energy or charge-transfer processes in artificial molecular assemblies. However, in recent days, the excimer has received much attention as a functional intermediate in the excited-state dynamics such as singlet fission or charge-separation processes. In this work, we show that the relative contribution to charge-transfer resonance of the excimer state in a bay-substituted perylene bisimide dimer cyclophane can be modulated by dielectric properties of the solvents employed. Solvent-dependent time-resolved fluorescence and absorption measurements reveal that an enhancement of charge-transfer resonance in the excimer state is reflected by incomplete symmetry-breaking charge-separation processes from the structurally relaxed excimer state by means of dipolar solvation processes in the high dielectric environment.
• Spectral and Structural Variations of Biomimetic Light-Harvesting Nanotubes. Löhner, A.; Kunsel, T.; Röhr, M. I. S.; Jansen, T. L. C.; Sengupta, S.; Würthner, F.; Knoester, J.; Köhler, J. In J. Phys. Chem. Lett., pp. 2715–2724. 2019.
  • [ Abstract ]
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  Bioinspired, self-assembled nanotubes have been investigated by low-temperature, polarization-resolved single-tube spectroscopy. These assemblies are based on zinc chlorin monomers and are considered as model systems that resemble the secondary structural elements in the natural light-harvesting systems of green (non)sulfur bacteria. Compared to the natural systems, the spectral parameters extracted from the single-nanotube spectra feature distributions with significantly smaller widths, which is ascribed to a tremendous reduction of structural heterogeneity in the artificial systems. Employing quantum chemical molecular modeling the spectra of individual nanotubes can be explained consistently only for a molecular packing model that is fundamentally different from those considered so far for the natural systems. Subsequent theoretical simulations reveal that the remaining spectral variations between single nanotubes can be traced back to small variations of the mutual orientations of the monomer transition dipole moments that are far beyond the resolving power of high-resolution electron microscopy imaging techniques.

  @article{L_hner_2019, abstract = {Bioinspired, self-assembled nanotubes have been investigated by low-temperature, polarization-resolved single-tube spectroscopy. These assemblies are based on zinc chlorin monomers and are considered as model systems that resemble the secondary structural elements in the natural light-harvesting systems of green (non)sulfur bacteria. Compared to the natural systems, the spectral parameters extracted from the single-nanotube spectra feature distributions with significantly smaller widths, which is ascribed to a tremendous reduction of structural heterogeneity in the artificial systems. Employing quantum chemical molecular modeling the spectra of individual nanotubes can be explained consistently only for a molecular packing model that is fundamentally different from those considered so far for the natural systems. Subsequent theoretical simulations reveal that the remaining spectral variations between single nanotubes can be traced back to small variations of the mutual orientations of the monomer transition dipole moments that are far beyond the resolving power of high-resolution electron microscopy imaging techniques.}, author = {Löhner, A. and Kunsel, T. and Röhr, M. I. S. and Jansen, T. L. C. and Sengupta, S. and Würthner, F. and Knoester, J. and Köhler, J.}, journal = {J. Phys. Chem. Lett.}, keywords = {myown}, month = {05}, pages = {2715–2724}, publisher = {American Chemical Society ({ACS})}, title = {Spectral and Structural Variations of Biomimetic Light-Harvesting Nanotubes.}, year = 2019 }

  %0 Journal Article %1 L_hner_2019 %A Löhner, A. %A Kunsel, T. %A Röhr, M. I. S. %A Jansen, T. L. C. %A Sengupta, S. %A Würthner, F. %A Knoester, J. %A Köhler, J. %D 2019 %I American Chemical Society (ACS) %J J. Phys. Chem. Lett. %P 2715--2724 %R 10.1021/acs.jpclett.9b00303 %T Spectral and Structural Variations of Biomimetic Light-Harvesting Nanotubes. %U https://doi.org/10.1021%2Facs.jpclett.9b00303 %X Bioinspired, self-assembled nanotubes have been investigated by low-temperature, polarization-resolved single-tube spectroscopy. These assemblies are based on zinc chlorin monomers and are considered as model systems that resemble the secondary structural elements in the natural light-harvesting systems of green (non)sulfur bacteria. Compared to the natural systems, the spectral parameters extracted from the single-nanotube spectra feature distributions with significantly smaller widths, which is ascribed to a tremendous reduction of structural heterogeneity in the artificial systems. Employing quantum chemical molecular modeling the spectra of individual nanotubes can be explained consistently only for a molecular packing model that is fundamentally different from those considered so far for the natural systems. Subsequent theoretical simulations reveal that the remaining spectral variations between single nanotubes can be traced back to small variations of the mutual orientations of the monomer transition dipole moments that are far beyond the resolving power of high-resolution electron microscopy imaging techniques.
• Synthesis of a Carbon Nanocone by Cascade Annulation. Shoyama, Kazutaka; Würthner, Frank. In J. Am. Chem. Soc., 141(33), pp. 13008–13012. 2019.
  • [ Abstract ]
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  More than 50 years have passed since the first observation of graphitic cones in the pyrolysis of carbon. However, to date there has been no report in the literature on the synthesis of such carbon allotropes. Here we present the first synthesis of a carbon nanocone, which comprises a pentagon encircled by 30 hexagons, by means of a palladium-catalyzed cross-coupling reaction. In this synthetic approach, 15 C–C bonds were constructed from a cone-shaped aromatic scaffold, corannulene, and five naphthalene dicarboximide moieties through a cascade of [3 + 3] and [4 + 2] annulations. The conical geometry of the first synthetic carbon nanocone was confirmed by X-ray crystallography. The optical and electronic properties of this graphitic cone were elucidated by UV/vis and fluorescence spectroscopy and cyclic voltammetry.

  @article{Shoyama_2019, abstract = {More than 50 years have passed since the first observation of graphitic cones in the pyrolysis of carbon. However, to date there has been no report in the literature on the synthesis of such carbon allotropes. Here we present the first synthesis of a carbon nanocone, which comprises a pentagon encircled by 30 hexagons, by means of a palladium-catalyzed cross-coupling reaction. In this synthetic approach, 15 C–C bonds were constructed from a cone-shaped aromatic scaffold, corannulene, and five naphthalene dicarboximide moieties through a cascade of [3 + 3] and [4 + 2] annulations. The conical geometry of the first synthetic carbon nanocone was confirmed by X-ray crystallography. The optical and electronic properties of this graphitic cone were elucidated by UV/vis and fluorescence spectroscopy and cyclic voltammetry.}, author = {Shoyama, Kazutaka and Würthner, Frank}, journal = {J. Am. Chem. Soc.}, keywords = {myown}, month = {08}, number = 33, pages = {13008-13012}, publisher = {American Chemical Society ({ACS})}, title = {Synthesis of a Carbon Nanocone by Cascade Annulation}, volume = 141, year = 2019 }

  %0 Journal Article %1 Shoyama_2019 %A Shoyama, Kazutaka %A Würthner, Frank %D 2019 %I American Chemical Society (ACS) %J J. Am. Chem. Soc. %N 33 %P 13008-13012 %R 10.1021/jacs.9b06617 %T Synthesis of a Carbon Nanocone by Cascade Annulation %U https://doi.org/10.1021%2Fjacs.9b06617 %V 141 %X More than 50 years have passed since the first observation of graphitic cones in the pyrolysis of carbon. However, to date there has been no report in the literature on the synthesis of such carbon allotropes. Here we present the first synthesis of a carbon nanocone, which comprises a pentagon encircled by 30 hexagons, by means of a palladium-catalyzed cross-coupling reaction. In this synthetic approach, 15 C–C bonds were constructed from a cone-shaped aromatic scaffold, corannulene, and five naphthalene dicarboximide moieties through a cascade of [3 + 3] and [4 + 2] annulations. The conical geometry of the first synthetic carbon nanocone was confirmed by X-ray crystallography. The optical and electronic properties of this graphitic cone were elucidated by UV/vis and fluorescence spectroscopy and cyclic voltammetry.
• Resonance Raman study of the J-type aggregation process of a water soluble perylene bisimide. Alloa, Elisa; Grande, Vincenzo; Dilmurat, Rishat; Beljonne, David; Würthner, Frank; Hayes, Sophia C. In Phys. Chem. Chem. Phys., 21(33), pp. 18300–18309. 2019.
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  Perylene bisimides (PBIs) are dyes known for combining high absorption and emission in the visible region with thermal and photochemical stability. H-bond-directed aggregation driven by free imide groups has been reported to promote the uncommon J-type aggregate formation of PBIs. J-aggregates are highly desired thanks to their bathochromically shifted narrow absorption and fluorescence due to excitonic coupling, together with hyperchromicity and superradiance compared to the monomer. Herein we present the water soluble MEG-PBI showing interesting aggregation in water and in the solid state. Unlike its hydrophobic counterparts, MEG-PBI aggregates in water with increasing temperature, indicating entropy-driven self-assembly. Temperature-dependent Resonance Raman (RR) spectroscopy was employed for the structural characterization of MEG-PBI in aqueous solution versus toluene and in aggregated thin films, employing excitation at different wavelengths to probe the contribution of various chromophores to the supramolecular structure of the aggregate. We find that the perylene core distorts upon aggregation, where the bonds along the perylene long N–N axis lengthen and the ones perpendicular to that shorten, suggesting a head-to-tail arrangement due to H-bonding between neighboring units.

  @article{C9CP01874C, abstract = {Perylene bisimides (PBIs) are dyes known for combining high absorption and emission in the visible region with thermal and photochemical stability. H-bond-directed aggregation driven by free imide groups has been reported to promote the uncommon J-type aggregate formation of PBIs. J-aggregates are highly desired thanks to their bathochromically shifted narrow absorption and fluorescence due to excitonic coupling{,} together with hyperchromicity and superradiance compared to the monomer. Herein we present the water soluble MEG-PBI showing interesting aggregation in water and in the solid state. Unlike its hydrophobic counterparts{,} MEG-PBI aggregates in water with increasing temperature{,} indicating entropy-driven self-assembly. Temperature-dependent Resonance Raman (RR) spectroscopy was employed for the structural characterization of MEG-PBI in aqueous solution versus toluene and in aggregated thin films{,} employing excitation at different wavelengths to probe the contribution of various chromophores to the supramolecular structure of the aggregate. We find that the perylene core distorts upon aggregation{,} where the bonds along the perylene long N–N axis lengthen and the ones perpendicular to that shorten{,} suggesting a head-to-tail arrangement due to H-bonding between neighboring units.}, author = {Alloa, Elisa and Grande, Vincenzo and Dilmurat, Rishat and Beljonne, David and Würthner, Frank and Hayes, Sophia C.}, journal = {Phys. Chem. Chem. Phys.}, keywords = {myown}, month = {07}, number = 33, pages = {18300-18309}, publisher = {The Royal Society of Chemistry}, title = {Resonance Raman study of the J-type aggregation process of a water soluble perylene bisimide}, volume = 21, year = 2019 }

  %0 Journal Article %1 C9CP01874C %A Alloa, Elisa %A Grande, Vincenzo %A Dilmurat, Rishat %A Beljonne, David %A Würthner, Frank %A Hayes, Sophia C. %D 2019 %I The Royal Society of Chemistry %J Phys. Chem. Chem. Phys. %N 33 %P 18300-18309 %R 10.1039/C9CP01874C %T Resonance Raman study of the J-type aggregation process of a water soluble perylene bisimide %U http://dx.doi.org/10.1039/C9CP01874C %V 21 %X Perylene bisimides (PBIs) are dyes known for combining high absorption and emission in the visible region with thermal and photochemical stability. H-bond-directed aggregation driven by free imide groups has been reported to promote the uncommon J-type aggregate formation of PBIs. J-aggregates are highly desired thanks to their bathochromically shifted narrow absorption and fluorescence due to excitonic coupling, together with hyperchromicity and superradiance compared to the monomer. Herein we present the water soluble MEG-PBI showing interesting aggregation in water and in the solid state. Unlike its hydrophobic counterparts, MEG-PBI aggregates in water with increasing temperature, indicating entropy-driven self-assembly. Temperature-dependent Resonance Raman (RR) spectroscopy was employed for the structural characterization of MEG-PBI in aqueous solution versus toluene and in aggregated thin films, employing excitation at different wavelengths to probe the contribution of various chromophores to the supramolecular structure of the aggregate. We find that the perylene core distorts upon aggregation, where the bonds along the perylene long N–N axis lengthen and the ones perpendicular to that shorten, suggesting a head-to-tail arrangement due to H-bonding between neighboring units.
• Essential States Model for Merocyanine Dye Stacks: BridgingElectronic and Optical Absorption Properties. Bialas, David; Chuwei, Zhong; Würthner, Frank; Spano, Frank C. In J. Phys. Chem. C., 123, pp. 18654–18664. 2019.
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  An extension of the essential states model isdeveloped to investigate the absorption and electronic properties of a highly dipolar merocyanine dye and double and quadruple π-stacks formed upon the folding and self-assembly of appropriate spacer-tethered bis(merocyanine)dyes. Our analysis reveals that a simple two-state model is not sufficient to adequately describe the absorption features of a single chromophore. However, by including an additional bridge state, the absorption features are well described and reasonable values for the permanent and transition dipole moments are obtained. We show that the low-energy absorption band of the folded double stack results from vibronic coupling, whereas the additional absorption shoulder observed in the spectrum of the self-assembled quadruple stack is due to a transition to a lower excited state. Furthermore, the chromophores within both π-stacks exhibit an increase in the charge-transfer character in the ground state with respect to the single chromophore arising from polarizability effects, which are not accounted for in the conventional Frenkel exciton theory.These insights are of significant importance for the proper design of functional materials based on merocyanines and dipolar chromophores in general.

  @article{noauthororeditor, abstract = {An extension of the essential states model isdeveloped to investigate the absorption and electronic properties of a highly dipolar merocyanine dye and double and quadruple π-stacks formed upon the folding and self-assembly of appropriate spacer-tethered bis(merocyanine)dyes. Our analysis reveals that a simple two-state model is not sufficient to adequately describe the absorption features of a single chromophore. However, by including an additional bridge state, the absorption features are well described and reasonable values for the permanent and transition dipole moments are obtained. We show that the low-energy absorption band of the folded double stack results from vibronic coupling, whereas the additional absorption shoulder observed in the spectrum of the self-assembled quadruple stack is due to a transition to a lower excited state. Furthermore, the chromophores within both π-stacks exhibit an increase in the charge-transfer character in the ground state with respect to the single chromophore arising from polarizability effects, which are not accounted for in the conventional Frenkel exciton theory.These insights are of significant importance for the proper design of functional materials based on merocyanines and dipolar chromophores in general.}, author = {Bialas, David and Chuwei, Zhong and Würthner, Frank and Spano, Frank C.}, journal = {J. Phys. Chem. C.}, keywords = {organic}, month = {07}, pages = {18654-18664}, title = {Essential States Model for Merocyanine Dye Stacks: BridgingElectronic and Optical Absorption Properties}, volume = 123, year = 2019 }

  %0 Journal Article %1 noauthororeditor %A Bialas, David %A Chuwei, Zhong %A Würthner, Frank %A Spano, Frank C. %D 2019 %J J. Phys. Chem. C. %P 18654-18664 %R 10.1021/acs.jpcc.9b04430 %T Essential States Model for Merocyanine Dye Stacks: BridgingElectronic and Optical Absorption Properties %U https://pubs.acs.org/doi/pdf/10.1021/acs.jpcc.9b04430?rand=pvfkkucl %V 123 %X An extension of the essential states model isdeveloped to investigate the absorption and electronic properties of a highly dipolar merocyanine dye and double and quadruple π-stacks formed upon the folding and self-assembly of appropriate spacer-tethered bis(merocyanine)dyes. Our analysis reveals that a simple two-state model is not sufficient to adequately describe the absorption features of a single chromophore. However, by including an additional bridge state, the absorption features are well described and reasonable values for the permanent and transition dipole moments are obtained. We show that the low-energy absorption band of the folded double stack results from vibronic coupling, whereas the additional absorption shoulder observed in the spectrum of the self-assembled quadruple stack is due to a transition to a lower excited state. Furthermore, the chromophores within both π-stacks exhibit an increase in the charge-transfer character in the ground state with respect to the single chromophore arising from polarizability effects, which are not accounted for in the conventional Frenkel exciton theory.These insights are of significant importance for the proper design of functional materials based on merocyanines and dipolar chromophores in general.
• Protein‐like Enwrapped Perylene Bisimide Chromophore as a Bright Microcrystalline Emitter Material. Schmidt, David; Stolte, Matthias; Süß, Jasmin; Liess, Andreas; Stepanenko, Vladimir; Würthner, Frank. In Angew. Chem. Int. Ed., 58(38), pp. 13385–13389. 2019.
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  Strongly emissive solid‐state materials are mandatory components for many emerging optoelectronic technologies, but fluorescence is often quenched in the solid state owing to strong intermolecular interactions. The design of new organic pigments, which retain their optical properties despite their high tendency to crystallize, could overcome such limitations. Herein, we show a new material with monomer‐like absorption and emission profiles as well as fluorescence quantum yields over 90 % in its crystalline solid state. The material was synthesized by attaching two bulky tris(4‐tert‐butylphenyl)phenoxy substituents at the perylene bisimide bay positions. These substituents direct a packing arrangement with full enwrapping of the chromophore and unidirectional chromophore alignment within the crystal lattice to afford optical properties that resemble those of their natural pigment counterparts, in which chromophores are rigidly embedded in protein environments.

  @article{noauthororeditor, abstract = {Strongly emissive solid‐state materials are mandatory components for many emerging optoelectronic technologies, but fluorescence is often quenched in the solid state owing to strong intermolecular interactions. The design of new organic pigments, which retain their optical properties despite their high tendency to crystallize, could overcome such limitations. Herein, we show a new material with monomer‐like absorption and emission profiles as well as fluorescence quantum yields over 90 % in its crystalline solid state. The material was synthesized by attaching two bulky tris(4‐tert‐butylphenyl)phenoxy substituents at the perylene bisimide bay positions. These substituents direct a packing arrangement with full enwrapping of the chromophore and unidirectional chromophore alignment within the crystal lattice to afford optical properties that resemble those of their natural pigment counterparts, in which chromophores are rigidly embedded in protein environments.}, author = {Schmidt, David and Stolte, Matthias and Süß, Jasmin and Liess, Andreas and Stepanenko, Vladimir and Würthner, Frank}, journal = {Angew. Chem. Int. Ed.}, keywords = {myown}, month = {07}, number = 38, pages = {13385-13389}, title = {Protein‐like Enwrapped Perylene Bisimide Chromophore as a Bright Microcrystalline Emitter Material}, volume = 58, year = 2019 }

  %0 Journal Article %1 noauthororeditor %A Schmidt, David %A Stolte, Matthias %A Süß, Jasmin %A Liess, Andreas %A Stepanenko, Vladimir %A Würthner, Frank %D 2019 %J Angew. Chem. Int. Ed. %N 38 %P 13385-13389 %R 10.1002/anie.201907618 %T Protein‐like Enwrapped Perylene Bisimide Chromophore as a Bright Microcrystalline Emitter Material %U https://onlinelibrary.wiley.com/doi/full/10.1002/anie.201907618 %V 58 %X Strongly emissive solid‐state materials are mandatory components for many emerging optoelectronic technologies, but fluorescence is often quenched in the solid state owing to strong intermolecular interactions. The design of new organic pigments, which retain their optical properties despite their high tendency to crystallize, could overcome such limitations. Herein, we show a new material with monomer‐like absorption and emission profiles as well as fluorescence quantum yields over 90 % in its crystalline solid state. The material was synthesized by attaching two bulky tris(4‐tert‐butylphenyl)phenoxy substituents at the perylene bisimide bay positions. These substituents direct a packing arrangement with full enwrapping of the chromophore and unidirectional chromophore alignment within the crystal lattice to afford optical properties that resemble those of their natural pigment counterparts, in which chromophores are rigidly embedded in protein environments.
• Supramolecular Block Copolymers by Seeded Living Polymerization of Perylene Bisimides. Wagner, Wolfgang; Wehner, Marius; Stepanenko, Vladimir; Würthner, Frank. In J. Am. Chem. Soc., 141(30), pp. 12044–12054. 2019.
  • [ Abstract ]
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  Living covalent polymerization has been a subject of intense research for many decades and has culminated in the synthesis of a large variety of block copolymers (BCPs) with structural and functional diversity. In contrast, the research on supramolecular BCPs is still in its infancy and their generation by living processes remains a challenge. Here we report the formation of supramolecular block copolymers by two-component seeded living polymerization of properly designed perylene bisimides (PBIs) under precise kinetic control. Our detailed studies on thermodynamically and kinetically controlled supramolecular polymerization of three investigated PBIs, which contain hydrogen-bonding amide side groups in imide position and chlorine, methoxy, or methylthio substituents in 1,7 bay-positions, revealed that these PBIs form kinetically metastable H-aggregates, which can be transformed into the thermodynamically favored J-aggregates by seed-induced living polymerization. We show here that copolymerization of kinetically trapped states of one PBI with seeds of another PBI leads to the formation of supramolecular block copolymers by chain-growth process from the seed termini as confirmed by UV/vis spectroscopy and atomic force microscopy (AFM). This work demonstrates for the first time the formation of triblock supramolecular polymer architectures with A-B-A and B-A-B block pattern by alternate two-component seeded polymerization in a living manner.

  @article{Wagner_2019, abstract = {Living covalent polymerization has been a subject of intense research for many decades and has culminated in the synthesis of a large variety of block copolymers (BCPs) with structural and functional diversity. In contrast, the research on supramolecular BCPs is still in its infancy and their generation by living processes remains a challenge. Here we report the formation of supramolecular block copolymers by two-component seeded living polymerization of properly designed perylene bisimides (PBIs) under precise kinetic control. Our detailed studies on thermodynamically and kinetically controlled supramolecular polymerization of three investigated PBIs, which contain hydrogen-bonding amide side groups in imide position and chlorine, methoxy, or methylthio substituents in 1,7 bay-positions, revealed that these PBIs form kinetically metastable H-aggregates, which can be transformed into the thermodynamically favored J-aggregates by seed-induced living polymerization. We show here that copolymerization of kinetically trapped states of one PBI with seeds of another PBI leads to the formation of supramolecular block copolymers by chain-growth process from the seed termini as confirmed by UV/vis spectroscopy and atomic force microscopy (AFM). This work demonstrates for the first time the formation of triblock supramolecular polymer architectures with A-B-A and B-A-B block pattern by alternate two-component seeded polymerization in a living manner.}, author = {Wagner, Wolfgang and Wehner, Marius and Stepanenko, Vladimir and Würthner, Frank}, journal = {J. Am. Chem. Soc.}, keywords = {myown}, month = {07}, number = 30, pages = {12044–12054}, publisher = {American Chemical Society ({ACS})}, title = {Supramolecular Block Copolymers by Seeded Living Polymerization of Perylene Bisimides}, volume = 141, year = 2019 }

  %0 Journal Article %1 Wagner_2019 %A Wagner, Wolfgang %A Wehner, Marius %A Stepanenko, Vladimir %A Würthner, Frank %D 2019 %I American Chemical Society (ACS) %J J. Am. Chem. Soc. %N 30 %P 12044--12054 %R 10.1021/jacs.9b04935 %T Supramolecular Block Copolymers by Seeded Living Polymerization of Perylene Bisimides %U https://doi.org/10.1021%2Fjacs.9b04935 %V 141 %X Living covalent polymerization has been a subject of intense research for many decades and has culminated in the synthesis of a large variety of block copolymers (BCPs) with structural and functional diversity. In contrast, the research on supramolecular BCPs is still in its infancy and their generation by living processes remains a challenge. Here we report the formation of supramolecular block copolymers by two-component seeded living polymerization of properly designed perylene bisimides (PBIs) under precise kinetic control. Our detailed studies on thermodynamically and kinetically controlled supramolecular polymerization of three investigated PBIs, which contain hydrogen-bonding amide side groups in imide position and chlorine, methoxy, or methylthio substituents in 1,7 bay-positions, revealed that these PBIs form kinetically metastable H-aggregates, which can be transformed into the thermodynamically favored J-aggregates by seed-induced living polymerization. We show here that copolymerization of kinetically trapped states of one PBI with seeds of another PBI leads to the formation of supramolecular block copolymers by chain-growth process from the seed termini as confirmed by UV/vis spectroscopy and atomic force microscopy (AFM). This work demonstrates for the first time the formation of triblock supramolecular polymer architectures with A-B-A and B-A-B block pattern by alternate two-component seeded polymerization in a living manner.
• Enhanced Electron Transportation by Dye Doping in Very Low-Temperature (<130 °C)-Processed Sol–Gel ZnO toward Flexible Organic Solar Cells.. Wen, Xinbo; Fang, Shaomao; Xu, Yucheng; Zheng, Nan; Liu, Linlin; Xie, Zengqi; Würthner, Frank. In ACS Appl. Mater. Interfaces, 11(37), pp. 34151–34157. 2019.
  • [ Abstract ]
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  A perylene bisimide functionalized with four 4-carboxyphenoxy substituents at bay area (PBI-COOH) was embedded in sol–gel-derived zinc oxide (ZnO) to fabricate organic–inorganic hybrid photoconductive cathode interlayers (ZnO:PBI-COOH) that can be annealed at a rather low temperature of 120–130 °C as desired for plastic substrates for flexible devices. For these interlayers, the structural defects including oxygen vacancy and residual hydroxy groups are reduced that leads to increased electron mobility, and a photoinduced electron transfer from the organic dopant into the conduction band of ZnO endows the hybrid thin film with relatively higher conductivity when compared to the undoped ZnO thin film. The low-temperature-processed hybrid thin films were applied on indium tin oxide electrodes to produce inverted organic solar cells (OSCs) with power conversion efficiencies of 11.68 and 13.48% when using J71:ITIC and PBDB-T-2Cl:IT4F as active layers, respectively. Finally, flexible OSCs are fabricated on poly(ethylene terephthalate) substrates that maintained stability with relatively high performance after 100 times bending.

  @article{noauthororeditor, abstract = {A perylene bisimide functionalized with four 4-carboxyphenoxy substituents at bay area (PBI-COOH) was embedded in sol–gel-derived zinc oxide (ZnO) to fabricate organic–inorganic hybrid photoconductive cathode interlayers (ZnO:PBI-COOH) that can be annealed at a rather low temperature of 120–130 °C as desired for plastic substrates for flexible devices. For these interlayers, the structural defects including oxygen vacancy and residual hydroxy groups are reduced that leads to increased electron mobility, and a photoinduced electron transfer from the organic dopant into the conduction band of ZnO endows the hybrid thin film with relatively higher conductivity when compared to the undoped ZnO thin film. The low-temperature-processed hybrid thin films were applied on indium tin oxide electrodes to produce inverted organic solar cells (OSCs) with power conversion efficiencies of 11.68 and 13.48% when using J71:ITIC and PBDB-T-2Cl:IT4F as active layers, respectively. Finally, flexible OSCs are fabricated on poly(ethylene terephthalate) substrates that maintained stability with relatively high performance after 100 times bending.}, author = {Wen, Xinbo and Fang, Shaomao and Xu, Yucheng and Zheng, Nan and Liu, Linlin and Xie, Zengqi and Würthner, Frank}, journal = {ACS Appl. Mater. Interfaces}, keywords = {myown}, month = {08}, number = 37, pages = {34151-34157}, title = {Enhanced Electron Transportation by Dye Doping in Very Low-Temperature (<130 °C)-Processed Sol–Gel ZnO toward Flexible Organic Solar Cells}, volume = 11, year = 2019 }

  %0 Journal Article %1 noauthororeditor %A Wen, Xinbo %A Fang, Shaomao %A Xu, Yucheng %A Zheng, Nan %A Liu, Linlin %A Xie, Zengqi %A Würthner, Frank %D 2019 %J ACS Appl. Mater. Interfaces %N 37 %P 34151-34157 %R 10.1021/acsami.9b10514 %T Enhanced Electron Transportation by Dye Doping in Very Low-Temperature (<130 °C)-Processed Sol–Gel ZnO toward Flexible Organic Solar Cells %U https://pubs.acs.org/doi/10.1021/acsami.9b10514 %V 11 %X A perylene bisimide functionalized with four 4-carboxyphenoxy substituents at bay area (PBI-COOH) was embedded in sol–gel-derived zinc oxide (ZnO) to fabricate organic–inorganic hybrid photoconductive cathode interlayers (ZnO:PBI-COOH) that can be annealed at a rather low temperature of 120–130 °C as desired for plastic substrates for flexible devices. For these interlayers, the structural defects including oxygen vacancy and residual hydroxy groups are reduced that leads to increased electron mobility, and a photoinduced electron transfer from the organic dopant into the conduction band of ZnO endows the hybrid thin film with relatively higher conductivity when compared to the undoped ZnO thin film. The low-temperature-processed hybrid thin films were applied on indium tin oxide electrodes to produce inverted organic solar cells (OSCs) with power conversion efficiencies of 11.68 and 13.48% when using J71:ITIC and PBDB-T-2Cl:IT4F as active layers, respectively. Finally, flexible OSCs are fabricated on poly(ethylene terephthalate) substrates that maintained stability with relatively high performance after 100 times bending.
• Photoinduced Energy‐ and Electron‐Transfer Processes in a Side‐to‐Face RuII‐Porphyrin/Perylene‐bisimide Array. Amati, Agnes; Natali, Mirco; Indelli, Maria Teresa; Iengo, Elisabetta; Würthner, Frank. In Chem. Phys. Chem., 20(17), pp. 2195–2203. 2019.
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  A side‐to‐face array DPy‐gPBI[Ru(4‐tBuTPP)(CO)]2, based on a “green” perylene bisimide chromophore sandwiched between two RuII‐porphyrins, has been prepared by self‐assembly. Its photophysical properties have been characterized in detail by a combination of steady‐state and time‐resolved techniques upon selective excitation of the two different components. Different photoinduced processes are observed as a function of the excitation wavelength. Electron transfer quenching is attained upon “red light” excitation of the perylene unit, whilst an energy transfer pathway is followed upon “green light” excitation of the metallo‐porphyrin moiety. Regardless of the excitation wavelength efficient population of the triplet excited state of the perylene chromophore is achieved. The photophysical results are discussed within the framework of classical electron transfer theory and compared with those of a previously reported system.

  @article{noauthororeditor, abstract = {A side‐to‐face array DPy‐gPBI[Ru(4‐tBuTPP)(CO)]2, based on a “green” perylene bisimide chromophore sandwiched between two RuII‐porphyrins, has been prepared by self‐assembly. Its photophysical properties have been characterized in detail by a combination of steady‐state and time‐resolved techniques upon selective excitation of the two different components. Different photoinduced processes are observed as a function of the excitation wavelength. Electron transfer quenching is attained upon “red light” excitation of the perylene unit, whilst an energy transfer pathway is followed upon “green light” excitation of the metallo‐porphyrin moiety. Regardless of the excitation wavelength efficient population of the triplet excited state of the perylene chromophore is achieved. The photophysical results are discussed within the framework of classical electron transfer theory and compared with those of a previously reported system.}, author = {Amati, Agnes and Natali, Mirco and Indelli, Maria Teresa and Iengo, Elisabetta and Würthner, Frank}, journal = {Chem. Phys. Chem.}, keywords = {myown}, month = {07}, number = 17, pages = {2195-2203}, title = {Photoinduced Energy‐ and Electron‐Transfer Processes in a Side‐to‐Face RuII‐Porphyrin/Perylene‐bisimide Array}, volume = 20, year = 2019 }

  %0 Journal Article %1 noauthororeditor %A Amati, Agnes %A Natali, Mirco %A Indelli, Maria Teresa %A Iengo, Elisabetta %A Würthner, Frank %D 2019 %J Chem. Phys. Chem. %N 17 %P 2195-2203 %R 10.1002/cphc.201900611 %T Photoinduced Energy‐ and Electron‐Transfer Processes in a Side‐to‐Face RuII‐Porphyrin/Perylene‐bisimide Array %U https://onlinelibrary.wiley.com/doi/full/10.1002/cphc.201900611 %V 20 %X A side‐to‐face array DPy‐gPBI[Ru(4‐tBuTPP)(CO)]2, based on a “green” perylene bisimide chromophore sandwiched between two RuII‐porphyrins, has been prepared by self‐assembly. Its photophysical properties have been characterized in detail by a combination of steady‐state and time‐resolved techniques upon selective excitation of the two different components. Different photoinduced processes are observed as a function of the excitation wavelength. Electron transfer quenching is attained upon “red light” excitation of the perylene unit, whilst an energy transfer pathway is followed upon “green light” excitation of the metallo‐porphyrin moiety. Regardless of the excitation wavelength efficient population of the triplet excited state of the perylene chromophore is achieved. The photophysical results are discussed within the framework of classical electron transfer theory and compared with those of a previously reported system.
• Bis(merocyanine) Hetero-Folda-Dimers: Evaluation of Exciton Coupling between Different Types of π-Stacked Chromphores. Kirchner, Eva; Bialas, David; Würthner, Frank. In Chem. Eur. J., 25, pp. 11294–11301. 2019.
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  Exciton coupling between different types of chromophores has been rarely investigated. Herein, a systematic study on the exciton coupling between merocyanine chromophores of different conjugation length with varying excited state energies is presented. In this work well-defined hetero-dimer stacks were obtained upon folding of bis(merocyanine) dyes in nonpolar solvents. They show distinctly different absorption properties in comparison with the spectra of the single chromophores, revealing a significant coupling between the different chromophores. The simulated absorption spectra obtained from time-dependent density functional theory (TD-DFT) calculations are in good agreement with the experimental spectra. Our theoretical analysis based on an extension of Kasha’s exciton theory discloses strong coupling between the dyes’ transition dipole moments despite of an excited-state energy difference of 0.60 eV between the chromophores.

  @article{Kirchner_2019, abstract = {Exciton coupling between different types of chromophores has been rarely investigated. Herein, a systematic study on the exciton coupling between merocyanine chromophores of different conjugation length with varying excited state energies is presented. In this work well-defined hetero-dimer stacks were obtained upon folding of bis(merocyanine) dyes in nonpolar solvents. They show distinctly different absorption properties in comparison with the spectra of the single chromophores, revealing a significant coupling between the different chromophores. The simulated absorption spectra obtained from time-dependent density functional theory (TD-DFT) calculations are in good agreement with the experimental spectra. Our theoretical analysis based on an extension of Kasha’s exciton theory discloses strong coupling between the dyes’ transition dipole moments despite of an excited-state energy difference of 0.60 eV between the chromophores.}, author = {Kirchner, Eva and Bialas, David and Würthner, Frank}, journal = {Chem. Eur. J.}, keywords = {myown}, month = {08}, pages = {11294-11301}, publisher = {Wiley}, title = {Bis(merocyanine) Hetero-Folda-Dimers: Evaluation of Exciton Coupling between Different Types of π-Stacked Chromphores}, volume = 25, year = 2019 }

  %0 Journal Article %1 Kirchner_2019 %A Kirchner, Eva %A Bialas, David %A Würthner, Frank %D 2019 %I Wiley %J Chem. Eur. J. %P 11294-11301 %R 10.1002/chem.201901757 %T Bis(merocyanine) Hetero-Folda-Dimers: Evaluation of Exciton Coupling between Different Types of π-Stacked Chromphores %U https://doi.org/10.1002%2Fchem.201901757 %V 25 %X Exciton coupling between different types of chromophores has been rarely investigated. Herein, a systematic study on the exciton coupling between merocyanine chromophores of different conjugation length with varying excited state energies is presented. In this work well-defined hetero-dimer stacks were obtained upon folding of bis(merocyanine) dyes in nonpolar solvents. They show distinctly different absorption properties in comparison with the spectra of the single chromophores, revealing a significant coupling between the different chromophores. The simulated absorption spectra obtained from time-dependent density functional theory (TD-DFT) calculations are in good agreement with the experimental spectra. Our theoretical analysis based on an extension of Kasha’s exciton theory discloses strong coupling between the dyes’ transition dipole moments despite of an excited-state energy difference of 0.60 eV between the chromophores.
• Impact of Molecular Shape on Supramolecular Copolymer Synthesis in Seeded Living Polymerization of Perylene Bisimides. Wagner, Wolfgang; Wehner, Marius; Stepanenko, Vladimir; Würthner, Frank. In CCS Chem., 1, pp. 598–613. 2019.
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  Impact of Molecular Shape onSupramolecular Copolymer Synthesisin Seeded Living Polymerization ofPerylene BisimidesWolfgang Wagner1,2, Marius Wehner1,2, Vladimir Stepanenko2& Frank Würthner1,2*1Center for Nanosystems Chemistry (CNC) and Bavarian Polymer Institute (BPI), Universität Würzburg,Theodor-Boveri-Weg, Würzburg 97074, (Germany),2Institut für Organische Chemie, Universität Würzburg,Würzburg 97074, (Germany)*Corresponding author:wuerthner@uni-wuerzburg.deCite this:CCS Chem.2019,1, 598–613Supramolecular polymerization properties have beenstudied for a series of perylene bisimide (PBI) dyescontaining identical hydrogen-bonding amide groupsin imide positions but variable number or size ofalkoxy substituents in bay-positions. Temperature-and time-dependent UV/vis and atomic force micros-copy (AFM) studies revealed that the number andsteric demand of the alkoxy substituents in bay-positions has a strong impact on thermodynamically,and more importantly, on kinetically controlled supra-molecular polymerization of these PBIs in solventmixtures of methylcyclohexane and toluene. Our stud-ies revealed that in the case of core tri- and tetra-methoxy-substituted PBIs, the kinetically controlledaggregation pathway was suppressed completely,whereas monomethoxy and 1,7-dialkoxy PBI deriva-tives form kinetically trapped species. Besides, themonomethoxy-substituted PBI could be used suc-cessfully in self-seeded chain-growth polymerizationof monomeric building blocks under precisely kineti-cally controlled conditions to obtain supramolecularpolymers with controlled length and low polydisper-sity. Further, two-component seed-induced livingcopolymerization of the present PBI series revealedthat the formation of supramolecular block copoly-mers is only feasible for appropriate combinationsof PBIs and that the seeding efficiency is stronglydependent on the shape complementarity of the in-dividual components applied. Thus, seeded supramo-lecular polymerization and copolymerization of PBIscould be modulated by subtle changes of the mole-cular shape through rational design of monomers.Keywords:supramolecular polymer, self-assembly,living supramolecular polymerization, block copoly-mers, perylene bisimides

  @article{noauthororeditor, abstract = {Impact of Molecular Shape onSupramolecular Copolymer Synthesisin Seeded Living Polymerization ofPerylene BisimidesWolfgang Wagner1,2, Marius Wehner1,2, Vladimir Stepanenko2& Frank Würthner1,2*1Center for Nanosystems Chemistry (CNC) and Bavarian Polymer Institute (BPI), Universität Würzburg,Theodor-Boveri-Weg, Würzburg 97074, (Germany),2Institut für Organische Chemie, Universität Würzburg,Würzburg 97074, (Germany)*Corresponding author:wuerthner@uni-wuerzburg.deCite this:CCS Chem.2019,1, 598–613Supramolecular polymerization properties have beenstudied for a series of perylene bisimide (PBI) dyescontaining identical hydrogen-bonding amide groupsin imide positions but variable number or size ofalkoxy substituents in bay-positions. Temperature-and time-dependent UV/vis and atomic force micros-copy (AFM) studies revealed that the number andsteric demand of the alkoxy substituents in bay-positions has a strong impact on thermodynamically,and more importantly, on kinetically controlled supra-molecular polymerization of these PBIs in solventmixtures of methylcyclohexane and toluene. Our stud-ies revealed that in the case of core tri- and tetra-methoxy-substituted PBIs, the kinetically controlledaggregation pathway was suppressed completely,whereas monomethoxy and 1,7-dialkoxy PBI deriva-tives form kinetically trapped species. Besides, themonomethoxy-substituted PBI could be used suc-cessfully in self-seeded chain-growth polymerizationof monomeric building blocks under precisely kineti-cally controlled conditions to obtain supramolecularpolymers with controlled length and low polydisper-sity. Further, two-component seed-induced livingcopolymerization of the present PBI series revealedthat the formation of supramolecular block copoly-mers is only feasible for appropriate combinationsof PBIs and that the seeding efficiency is stronglydependent on the shape complementarity of the in-dividual components applied. Thus, seeded supramo-lecular polymerization and copolymerization of PBIscould be modulated by subtle changes of the mole-cular shape through rational design of monomers.Keywords:supramolecular polymer, self-assembly,living supramolecular polymerization, block copoly-mers, perylene bisimides}, author = {Wagner, Wolfgang and Wehner, Marius and Stepanenko, Vladimir and Würthner, Frank}, journal = {CCS Chem.}, keywords = {myown}, month = 12, pages = {598-613}, title = {Impact of Molecular Shape on Supramolecular Copolymer Synthesis in Seeded Living Polymerization of Perylene Bisimides}, volume = 1, year = 2019 }

  %0 Journal Article %1 noauthororeditor %A Wagner, Wolfgang %A Wehner, Marius %A Stepanenko, Vladimir %A Würthner, Frank %D 2019 %J CCS Chem. %P 598-613 %R 10.31635/ccschem.019.20190061 %T Impact of Molecular Shape on Supramolecular Copolymer Synthesis in Seeded Living Polymerization of Perylene Bisimides %U https://www.chinesechemsoc.org/doi/10.31635/ccschem.019.20190061 %V 1 %X Impact of Molecular Shape onSupramolecular Copolymer Synthesisin Seeded Living Polymerization ofPerylene BisimidesWolfgang Wagner1,2, Marius Wehner1,2, Vladimir Stepanenko2& Frank Würthner1,2*1Center for Nanosystems Chemistry (CNC) and Bavarian Polymer Institute (BPI), Universität Würzburg,Theodor-Boveri-Weg, Würzburg 97074, (Germany),2Institut für Organische Chemie, Universität Würzburg,Würzburg 97074, (Germany)*Corresponding author:wuerthner@uni-wuerzburg.deCite this:CCS Chem.2019,1, 598–613Supramolecular polymerization properties have beenstudied for a series of perylene bisimide (PBI) dyescontaining identical hydrogen-bonding amide groupsin imide positions but variable number or size ofalkoxy substituents in bay-positions. Temperature-and time-dependent UV/vis and atomic force micros-copy (AFM) studies revealed that the number andsteric demand of the alkoxy substituents in bay-positions has a strong impact on thermodynamically,and more importantly, on kinetically controlled supra-molecular polymerization of these PBIs in solventmixtures of methylcyclohexane and toluene. Our stud-ies revealed that in the case of core tri- and tetra-methoxy-substituted PBIs, the kinetically controlledaggregation pathway was suppressed completely,whereas monomethoxy and 1,7-dialkoxy PBI deriva-tives form kinetically trapped species. Besides, themonomethoxy-substituted PBI could be used suc-cessfully in self-seeded chain-growth polymerizationof monomeric building blocks under precisely kineti-cally controlled conditions to obtain supramolecularpolymers with controlled length and low polydisper-sity. Further, two-component seed-induced livingcopolymerization of the present PBI series revealedthat the formation of supramolecular block copoly-mers is only feasible for appropriate combinationsof PBIs and that the seeding efficiency is stronglydependent on the shape complementarity of the in-dividual components applied. Thus, seeded supramo-lecular polymerization and copolymerization of PBIscould be modulated by subtle changes of the mole-cular shape through rational design of monomers.Keywords:supramolecular polymer, self-assembly,living supramolecular polymerization, block copoly-mers, perylene bisimides
• Bis(merocyanine) Homo-Folda-Dimers: Evaluation of Electronic and Spectral Changes in Well-Defined Dye Aggregate Geometries. Kirchner, Eva; Bialas, David; Wehner, Marius; Schmidt, David; Würthner, Frank. In Chem. Eur. J., 25, pp. 11285–11293. 2019.
  • [ Abstract ]
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  A series of three bis(merocyanine) dyes comprising chromophores of different conjugation lengths has been synthesized and the intramolecular aggregation process was investigated by UV/Vis absorption spectroscopy. The spectral changes observed upon variation of the solvent polarity reveal a folding process resulting in a cofacial π-stack of two chromophores with a decrease of the aggregation tendency with increasing chromophore length and solvent polarity. Solvent-dependent UV/Vis studies of the monomeric reference dyes show a significant increase of the polyene-like character for dyes with longer polymethine chains in nonpolar solvents, which is reversed upon aggregation due to the polarizability effect of the adjacent chromophore within the dye stack. The pronounced hypsochromic shift of the absorption band observed upon aggregation indicates strong coupling of the dyes’ transition dipole moments, which was confirmed by quantum-chemical analysis.

  @article{Kirchner_2019, abstract = {A series of three bis(merocyanine) dyes comprising chromophores of different conjugation lengths has been synthesized and the intramolecular aggregation process was investigated by UV/Vis absorption spectroscopy. The spectral changes observed upon variation of the solvent polarity reveal a folding process resulting in a cofacial π-stack of two chromophores with a decrease of the aggregation tendency with increasing chromophore length and solvent polarity. Solvent-dependent UV/Vis studies of the monomeric reference dyes show a significant increase of the polyene-like character for dyes with longer polymethine chains in nonpolar solvents, which is reversed upon aggregation due to the polarizability effect of the adjacent chromophore within the dye stack. The pronounced hypsochromic shift of the absorption band observed upon aggregation indicates strong coupling of the dyes’ transition dipole moments, which was confirmed by quantum-chemical analysis.}, author = {Kirchner, Eva and Bialas, David and Wehner, Marius and Schmidt, David and Würthner, Frank}, journal = {Chem. Eur. J.}, keywords = {myown}, month = {08}, pages = {11285-11293}, publisher = {Wiley}, title = {Bis(merocyanine) Homo-Folda-Dimers: Evaluation of Electronic and Spectral Changes in Well-Defined Dye Aggregate Geometries}, volume = 25, year = 2019 }

  %0 Journal Article %1 Kirchner_2019 %A Kirchner, Eva %A Bialas, David %A Wehner, Marius %A Schmidt, David %A Würthner, Frank %D 2019 %I Wiley %J Chem. Eur. J. %P 11285-11293 %R 10.1002/chem.201901754 %T Bis(merocyanine) Homo-Folda-Dimers: Evaluation of Electronic and Spectral Changes in Well-Defined Dye Aggregate Geometries %U https://doi.org/10.1002%2Fchem.201901754 %V 25 %X A series of three bis(merocyanine) dyes comprising chromophores of different conjugation lengths has been synthesized and the intramolecular aggregation process was investigated by UV/Vis absorption spectroscopy. The spectral changes observed upon variation of the solvent polarity reveal a folding process resulting in a cofacial π-stack of two chromophores with a decrease of the aggregation tendency with increasing chromophore length and solvent polarity. Solvent-dependent UV/Vis studies of the monomeric reference dyes show a significant increase of the polyene-like character for dyes with longer polymethine chains in nonpolar solvents, which is reversed upon aggregation due to the polarizability effect of the adjacent chromophore within the dye stack. The pronounced hypsochromic shift of the absorption band observed upon aggregation indicates strong coupling of the dyes’ transition dipole moments, which was confirmed by quantum-chemical analysis.
• Ultrafast coherent exciton dynamics in size-controlled perylene bisimide aggregates. Kang, Seongsoo; Kaufmann, Christina; Hong, Yongseok; Kim, Woojae; Nowak-Król, Agnieszka; Würthner, Frank; Kim, Dongho. In Struct. Dyn., 6, pp. 064501–1. 2019.
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  For H-aggregates of perylene bisimide (PBI), it has been reported that upon photoexcitation, an initially delocalized Frenkel exciton is localized by excimer formation. However, in recent studies, the beforehand exciton dynamics preceding the excimer formation was suggested in larger aggregates consisting of at least more than 10-PBI subunits, which was not observed in small aggregates comprising less than four-PBI subunits. This feature implies that the size of molecular aggregates plays a crucial role in the initial exciton dynamics. In this regard, we have tried to unveil the initial exciton dynamics in PBI H-aggregates by tracking down the transient reorientations of electronic transition dipoles formed by interactions between the PBI subunits in systematically size-controlled PBI H-aggregates. The ultrafast coherent exciton dynamics depending on the molecular aggregate sizes can be distinguished using polarization-dependent femtosecond-transient absorption anisotropy spectroscopic measurements with a time resolution of ∼40 fs. The ultrafast decay profiles of the anisotropy values are unaffected by vibrational relaxation and rotational diffusion processes; hence, the coherent exciton dynamics of the PBI H-aggregates prior to the excimer formation can be directly revealed as the energy migration processes along the PBI H-aggregates.

  @article{noauthororeditor, abstract = {For H-aggregates of perylene bisimide (PBI), it has been reported that upon photoexcitation, an initially delocalized Frenkel exciton is localized by excimer formation. However, in recent studies, the beforehand exciton dynamics preceding the excimer formation was suggested in larger aggregates consisting of at least more than 10-PBI subunits, which was not observed in small aggregates comprising less than four-PBI subunits. This feature implies that the size of molecular aggregates plays a crucial role in the initial exciton dynamics. In this regard, we have tried to unveil the initial exciton dynamics in PBI H-aggregates by tracking down the transient reorientations of electronic transition dipoles formed by interactions between the PBI subunits in systematically size-controlled PBI H-aggregates. The ultrafast coherent exciton dynamics depending on the molecular aggregate sizes can be distinguished using polarization-dependent femtosecond-transient absorption anisotropy spectroscopic measurements with a time resolution of ∼40 fs. The ultrafast decay profiles of the anisotropy values are unaffected by vibrational relaxation and rotational diffusion processes; hence, the coherent exciton dynamics of the PBI H-aggregates prior to the excimer formation can be directly revealed as the energy migration processes along the PBI H-aggregates.}, author = {Kang, Seongsoo and Kaufmann, Christina and Hong, Yongseok and Kim, Woojae and Nowak-Król, Agnieszka and Würthner, Frank and Kim, Dongho}, journal = {Struct. Dyn.}, keywords = {myown}, month = 11, pages = {064501-1-045601-8}, title = {Ultrafast coherent exciton dynamics in size-controlled perylene bisimide aggregates}, volume = 6, year = 2019 }

  %0 Journal Article %1 noauthororeditor %A Kang, Seongsoo %A Kaufmann, Christina %A Hong, Yongseok %A Kim, Woojae %A Nowak-Król, Agnieszka %A Würthner, Frank %A Kim, Dongho %D 2019 %J Struct. Dyn. %P 064501-1-045601-8 %R 10.1063/1.5124148 %T Ultrafast coherent exciton dynamics in size-controlled perylene bisimide aggregates %U https://aca.scitation.org/doi/10.1063/1.5124148 %V 6 %X For H-aggregates of perylene bisimide (PBI), it has been reported that upon photoexcitation, an initially delocalized Frenkel exciton is localized by excimer formation. However, in recent studies, the beforehand exciton dynamics preceding the excimer formation was suggested in larger aggregates consisting of at least more than 10-PBI subunits, which was not observed in small aggregates comprising less than four-PBI subunits. This feature implies that the size of molecular aggregates plays a crucial role in the initial exciton dynamics. In this regard, we have tried to unveil the initial exciton dynamics in PBI H-aggregates by tracking down the transient reorientations of electronic transition dipoles formed by interactions between the PBI subunits in systematically size-controlled PBI H-aggregates. The ultrafast coherent exciton dynamics depending on the molecular aggregate sizes can be distinguished using polarization-dependent femtosecond-transient absorption anisotropy spectroscopic measurements with a time resolution of ∼40 fs. The ultrafast decay profiles of the anisotropy values are unaffected by vibrational relaxation and rotational diffusion processes; hence, the coherent exciton dynamics of the PBI H-aggregates prior to the excimer formation can be directly revealed as the energy migration processes along the PBI H-aggregates.
• Photoconductive Core–Shell Liquid‐Crystals of a Perylene Bisimide J‐Aggregate Donor–Acceptor Dyad. Hecht, Markus; Schlossarek, Tim; Stolte, Matthias; Lehmann, Matthias; Würthner, Frank. In Angew. Chem. Int. Ed., 58, pp. 12979–12983. 2019.
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  A novel core–shell structured columnar liquid crystal composed of a donor‐acceptor dyad of tetraphenoxy perylene bisimide (PBI), decorated with four bithiophene units on the periphery, was synthesized. This molecule self‐assembles in solution into helical J‐aggregates guided by π–π interactions and hydrogen bonds which organize into a liquid‐crystalline (LC) columnar hexagonal domain in the solid state. Donor and acceptor moieties exhibit contrasting exciton coupling behavior with the PBIs’ (J‐type) transition dipole moment parallel and the bithiophene side arms’ (H‐type) perpendicular to the columnar axis. The dyad shows efficient energy and electron transfer in solution as well as in the solid state. The synergy of photoinduced electron transfer (PET) and charge transport along the narcissistically self‐assembled core–shell structure enables the implementation of the dye in two‐contact photoconductivity devices giving rise to a 20‐fold increased photoresponse compared to a reference dye without bithiophene donor moieties.

  @article{noauthororeditor, abstract = {A novel core–shell structured columnar liquid crystal composed of a donor‐acceptor dyad of tetraphenoxy perylene bisimide (PBI), decorated with four bithiophene units on the periphery, was synthesized. This molecule self‐assembles in solution into helical J‐aggregates guided by π–π interactions and hydrogen bonds which organize into a liquid‐crystalline (LC) columnar hexagonal domain in the solid state. Donor and acceptor moieties exhibit contrasting exciton coupling behavior with the PBIs’ (J‐type) transition dipole moment parallel and the bithiophene side arms’ (H‐type) perpendicular to the columnar axis. The dyad shows efficient energy and electron transfer in solution as well as in the solid state. The synergy of photoinduced electron transfer (PET) and charge transport along the narcissistically self‐assembled core–shell structure enables the implementation of the dye in two‐contact photoconductivity devices giving rise to a 20‐fold increased photoresponse compared to a reference dye without bithiophene donor moieties.}, author = {Hecht, Markus and Schlossarek, Tim and Stolte, Matthias and Lehmann, Matthias and Würthner, Frank}, journal = {Angew. Chem. Int. Ed.}, keywords = {myown}, month = {09}, pages = {12979-12983}, title = {Photoconductive Core–Shell Liquid‐Crystals of a Perylene Bisimide J‐Aggregate Donor–Acceptor Dyad}, volume = 58, year = 2019 }

  %0 Journal Article %1 noauthororeditor %A Hecht, Markus %A Schlossarek, Tim %A Stolte, Matthias %A Lehmann, Matthias %A Würthner, Frank %D 2019 %J Angew. Chem. Int. Ed. %P 12979-12983 %R 10.1002/anie.201904789 %T Photoconductive Core–Shell Liquid‐Crystals of a Perylene Bisimide J‐Aggregate Donor–Acceptor Dyad %V 58 %X A novel core–shell structured columnar liquid crystal composed of a donor‐acceptor dyad of tetraphenoxy perylene bisimide (PBI), decorated with four bithiophene units on the periphery, was synthesized. This molecule self‐assembles in solution into helical J‐aggregates guided by π–π interactions and hydrogen bonds which organize into a liquid‐crystalline (LC) columnar hexagonal domain in the solid state. Donor and acceptor moieties exhibit contrasting exciton coupling behavior with the PBIs’ (J‐type) transition dipole moment parallel and the bithiophene side arms’ (H‐type) perpendicular to the columnar axis. The dyad shows efficient energy and electron transfer in solution as well as in the solid state. The synergy of photoinduced electron transfer (PET) and charge transport along the narcissistically self‐assembled core–shell structure enables the implementation of the dye in two‐contact photoconductivity devices giving rise to a 20‐fold increased photoresponse compared to a reference dye without bithiophene donor moieties.
• Tetrahydroxy‐Perylene Bisimide Embedded in a Zinc Oxide Thin Film as an Electron‐Transporting Layer for High‐Performance Non‐Fullerene Organic Solar Cells. Wen, Xinbo; Nowak‐Król, Agnieszka; Nagler, Oliver; Kraus, Felix; Zhu, Na; Zheng, Nan; Müller, Matthias; Schmidt, David; Xie, Zengqi; Würthner, Frank. In Angew. Chem. Int. Ed., 58, pp. 13051–13055. 2019.
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  By introduction of four hydroxy (HO) groups into the two perylene bisimide (PBI) bay areas, new HO‐PBI ligands were obtained which upon deprotonation can complex ZnII ions and photosensitize semiconductive zinc oxide thin films. Such coordination is beneficial for dispersing PBI photosensitizer molecules evenly into metal oxide films to fabricate organic–inorganic hybrid interlayers for organic solar cells. Supported by the photoconductive effect of the ZnO:HO‐PBI hybrid interlayers, improved electron collection and transportation is achieved in fullerene and non‐fullerene polymer solar cell devices, leading to remarkable power conversion efficiencies of up to 15.95 % for a non‐fullerene based organic solar cell.

  @article{noauthororeditor, abstract = {By introduction of four hydroxy (HO) groups into the two perylene bisimide (PBI) bay areas, new HO‐PBI ligands were obtained which upon deprotonation can complex ZnII ions and photosensitize semiconductive zinc oxide thin films. Such coordination is beneficial for dispersing PBI photosensitizer molecules evenly into metal oxide films to fabricate organic–inorganic hybrid interlayers for organic solar cells. Supported by the photoconductive effect of the ZnO:HO‐PBI hybrid interlayers, improved electron collection and transportation is achieved in fullerene and non‐fullerene polymer solar cell devices, leading to remarkable power conversion efficiencies of up to 15.95 % for a non‐fullerene based organic solar cell.}, author = {Wen, Xinbo and Nowak‐Król, Agnieszka and Nagler, Oliver and Kraus, Felix and Zhu, Na and Zheng, Nan and Müller, Matthias and Schmidt, David and Xie, Zengqi and Würthner, Frank}, journal = {Angew. Chem. Int. Ed.}, keywords = {myown}, month = {09}, pages = {13051-13055}, title = {Tetrahydroxy‐Perylene Bisimide Embedded in a Zinc Oxide Thin Film as an Electron‐Transporting Layer for High‐Performance Non‐Fullerene Organic Solar Cells}, volume = 58, year = 2019 }

  %0 Journal Article %1 noauthororeditor %A Wen, Xinbo %A Nowak‐Król, Agnieszka %A Nagler, Oliver %A Kraus, Felix %A Zhu, Na %A Zheng, Nan %A Müller, Matthias %A Schmidt, David %A Xie, Zengqi %A Würthner, Frank %D 2019 %J Angew. Chem. Int. Ed. %P 13051-13055 %R 10.1002/anie.201907467 %T Tetrahydroxy‐Perylene Bisimide Embedded in a Zinc Oxide Thin Film as an Electron‐Transporting Layer for High‐Performance Non‐Fullerene Organic Solar Cells %V 58 %X By introduction of four hydroxy (HO) groups into the two perylene bisimide (PBI) bay areas, new HO‐PBI ligands were obtained which upon deprotonation can complex ZnII ions and photosensitize semiconductive zinc oxide thin films. Such coordination is beneficial for dispersing PBI photosensitizer molecules evenly into metal oxide films to fabricate organic–inorganic hybrid interlayers for organic solar cells. Supported by the photoconductive effect of the ZnO:HO‐PBI hybrid interlayers, improved electron collection and transportation is achieved in fullerene and non‐fullerene polymer solar cell devices, leading to remarkable power conversion efficiencies of up to 15.95 % for a non‐fullerene based organic solar cell.
• Near‐Infrared Quadrupolar Chromophores Combining Three‐Coordinate Boron‐Based Superdonor and Superacceptor Units. E.Stennett, Tom; Bissinger, Philipp; Griesbeck, Stefanie; Ullrich, Stefan; Krummenacher, Ivo; Auth, Michael; Sperlich, Andreas; Stolte, Matthias; Radacki, Krzysztof; Yao, Chang-Jiang; Würthner, Frank; Steffen, Andreas; Marder, Todd B.; Braunschweig, Holger. In Angew. Chem. Int. Ed., 58, pp. 6449–6454. 2019.
  • [ Abstract ]
  • [ BibTeX ]
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  • [ DOI ]
  Herein, two new quadrupolar acceptor‐π‐donor‐π‐acceptor (A‐π‐D‐π‐A) chromophores have been prepared featuring a strongly electron‐donating diborene core and strongly electron‐accepting dimesitylboryl (BMes2) and bis(2,4,6‐tris(trifluoromethyl)phenyl)boryl (BFMes2) end groups. Analysis of the compounds by NMR spectroscopy, X‐ray crystallography, cyclic voltammetry, and UV/Vis‐NIR absorption and emission spectroscopy indicated that the compounds have extended conjugated π‐systems spanning their B4C8 cores. The combination of exceptionally potent π‐donor (diborene) and π‐acceptor (diarylboryl) groups, both based on trigonal boron, leads to very small HOMO–LUMO gaps, resulting in strong absorption in the near‐IR region with maxima in THF at 840 and 1092 nm and very high extinction coefficients of ca. 120 000 m−1 cm−1. Both molecules also display weak near‐IR fluorescence with small Stokes shifts.

  @article{estennett2019nearinfrared, abstract = {Herein, two new quadrupolar acceptor‐π‐donor‐π‐acceptor (A‐π‐D‐π‐A) chromophores have been prepared featuring a strongly electron‐donating diborene core and strongly electron‐accepting dimesitylboryl (BMes2) and bis(2,4,6‐tris(trifluoromethyl)phenyl)boryl (BFMes2) end groups. Analysis of the compounds by NMR spectroscopy, X‐ray crystallography, cyclic voltammetry, and UV/Vis‐NIR absorption and emission spectroscopy indicated that the compounds have extended conjugated π‐systems spanning their B4C8 cores. The combination of exceptionally potent π‐donor (diborene) and π‐acceptor (diarylboryl) groups, both based on trigonal boron, leads to very small HOMO–LUMO gaps, resulting in strong absorption in the near‐IR region with maxima in THF at 840 and 1092 nm and very high extinction coefficients of ca. 120 000 m−1 cm−1. Both molecules also display weak near‐IR fluorescence with small Stokes shifts.}, author = {E.Stennett, Tom and Bissinger, Philipp and Griesbeck, Stefanie and Ullrich, Stefan and Krummenacher, Ivo and Auth, Michael and Sperlich, Andreas and Stolte, Matthias and Radacki, Krzysztof and Yao, Chang-Jiang and Würthner, Frank and Steffen, Andreas and Marder, Todd B. and Braunschweig, Holger}, journal = {Angew. Chem. Int. Ed.}, keywords = {organic}, month = {05}, pages = {6449-6454}, title = {Near‐Infrared Quadrupolar Chromophores Combining Three‐Coordinate Boron‐Based Superdonor and Superacceptor Units}, volume = 58, year = 2019 }

  %0 Journal Article %1 estennett2019nearinfrared %A E.Stennett, Tom %A Bissinger, Philipp %A Griesbeck, Stefanie %A Ullrich, Stefan %A Krummenacher, Ivo %A Auth, Michael %A Sperlich, Andreas %A Stolte, Matthias %A Radacki, Krzysztof %A Yao, Chang-Jiang %A Würthner, Frank %A Steffen, Andreas %A Marder, Todd B. %A Braunschweig, Holger %D 2019 %J Angew. Chem. Int. Ed. %P 6449-6454 %R 10.1002/anie.201900889 %T Near‐Infrared Quadrupolar Chromophores Combining Three‐Coordinate Boron‐Based Superdonor and Superacceptor Units %V 58 %X Herein, two new quadrupolar acceptor‐π‐donor‐π‐acceptor (A‐π‐D‐π‐A) chromophores have been prepared featuring a strongly electron‐donating diborene core and strongly electron‐accepting dimesitylboryl (BMes2) and bis(2,4,6‐tris(trifluoromethyl)phenyl)boryl (BFMes2) end groups. Analysis of the compounds by NMR spectroscopy, X‐ray crystallography, cyclic voltammetry, and UV/Vis‐NIR absorption and emission spectroscopy indicated that the compounds have extended conjugated π‐systems spanning their B4C8 cores. The combination of exceptionally potent π‐donor (diborene) and π‐acceptor (diarylboryl) groups, both based on trigonal boron, leads to very small HOMO–LUMO gaps, resulting in strong absorption in the near‐IR region with maxima in THF at 840 and 1092 nm and very high extinction coefficients of ca. 120 000 m−1 cm−1. Both molecules also display weak near‐IR fluorescence with small Stokes shifts.
• Progress in the synthesis of perylene bisimide dyes. Nowak-Król, Agnieszka; Würthner, Frank. In Org. Chem. Front., 6(8), pp. 1272–1318. 2019.
  • [ Abstract ]
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  With their versatile absorption, fluorescence, n-type semiconducting and (photo-)stability properties, perylene bisimides have evolved as the most investigated compounds among polycyclic aromatic hydrocarbons during the last decade. In this review we collect the results from about 200 original publications, reporting a plethora of new perylene bisimide derivatives whose properties widely enrich the possibility for the application of these dyes beyond traditional fields. While some applications are highlighted, different from other recent reviews, our focus here is on the advances in the synthetic methodologies that have afforded new bay functionalizations, recently addressed functionalizations at the ortho-positions to the carbonyl groups, and annulation of carbo- and heterocyclic units. An impressive number of perylene bisimide oligomers are highlighted as well which are connected by single bonds or spiro linkage or in a fused manner, leading to arrays with fascinating optical and electronic properties.

  @article{C8QO01368C, abstract = {With their versatile absorption{,} fluorescence{,} n-type semiconducting and (photo-)stability properties{,} perylene bisimides have evolved as the most investigated compounds among polycyclic aromatic hydrocarbons during the last decade. In this review we collect the results from about 200 original publications{,} reporting a plethora of new perylene bisimide derivatives whose properties widely enrich the possibility for the application of these dyes beyond traditional fields. While some applications are highlighted{,} different from other recent reviews{,} our focus here is on the advances in the synthetic methodologies that have afforded new bay functionalizations{,} recently addressed functionalizations at the ortho-positions to the carbonyl groups{,} and annulation of carbo- and heterocyclic units. An impressive number of perylene bisimide oligomers are highlighted as well which are connected by single bonds or spiro linkage or in a fused manner{,} leading to arrays with fascinating optical and electronic properties.}, author = {Nowak-Król, Agnieszka and Würthner, Frank}, journal = {Org. Chem. Front.}, keywords = {organic}, month = {04}, number = 8, pages = {1272-1318}, publisher = {The Royal Society of Chemistry}, title = {Progress in the synthesis of perylene bisimide dyes}, volume = 6, year = 2019 }

  %0 Journal Article %1 C8QO01368C %A Nowak-Król, Agnieszka %A Würthner, Frank %D 2019 %I The Royal Society of Chemistry %J Org. Chem. Front. %N 8 %P 1272-1318 %R 10.1039/C8QO01368C %T Progress in the synthesis of perylene bisimide dyes %U http://dx.doi.org/10.1039/C8QO01368C %V 6 %X With their versatile absorption, fluorescence, n-type semiconducting and (photo-)stability properties, perylene bisimides have evolved as the most investigated compounds among polycyclic aromatic hydrocarbons during the last decade. In this review we collect the results from about 200 original publications, reporting a plethora of new perylene bisimide derivatives whose properties widely enrich the possibility for the application of these dyes beyond traditional fields. While some applications are highlighted, different from other recent reviews, our focus here is on the advances in the synthetic methodologies that have afforded new bay functionalizations, recently addressed functionalizations at the ortho-positions to the carbonyl groups, and annulation of carbo- and heterocyclic units. An impressive number of perylene bisimide oligomers are highlighted as well which are connected by single bonds or spiro linkage or in a fused manner, leading to arrays with fascinating optical and electronic properties.
• Ealamines A–H, a Series of Naphthylisoquinolines with the Rare 7,8′-Coupling Site, from the Congolese Liana Ancistrocladus ealaensis, Targeting Pancreatic Cancer Cells. Tshitenge, Dieudonné Tshitenge; Bruhn, Torsten; Feineis, Doris; Schmidt, David; Mudogo, Virima; Kaiser, Marcel; Brun, Reto; Würthner, Frank; Awale, Suresh; Bringmann, Gerhard. In J. Nat. Prod., 82(11), pp. 3150–3164. 2019.
  • [ Abstract ]
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  From the twigs and leaves of the Central African liana Ancistrocladus ealaensis (Ancistrocladaceae), a series of ten 7,8′-coupled naphthylisoquinoline alkaloids were isolated, comprising eight new compounds, named ealamines A–H (4a, 4b, 5–10), and two known ones, 6-O-demethylancistrobrevine A (11) and yaoundamine A (12), which had previously been found in related African Ancistrocladus species. Only one of the new compounds within this series, ealamine H (10), is a typical Ancistrocladaceae-type alkaloid, with 3S-configuration at C-3 and an oxygen function at C-6, whereas seven of the new alkaloids are the first 7,8′-linked “hybrid-type” naphthylisoquinoline alkaloids, i.e., 3R-configured and 6-oxygenated in the tetrahydroisoquinoline part. The discovery of such a broad series of 7,8′-coupled naphthyltetrahydroisoquinolines is unprecedented, because representatives of this subclass of alkaloids are normally found in Nature quite rarely. The stereostructures of the new ealamines were assigned by HRESIMS, 1D and 2D NMR, oxidative degradation, and experimental and quantum-chemical ECD investigations, and—in the case of ealamine A (4a)—also confirmed by X-ray diffraction analysis. Ealamines A–D exhibited distinct—and specific—antiplasmodial activities, and they displayed pronounced preferential cytotoxic effects toward PANC-1 human pancreatic cancer cells in nutrient-deprived medium, without causing toxicity under normal, nutrient-rich conditions, with ealamine C (5) as the most potent agent.

  @article{noauthororeditor, abstract = {From the twigs and leaves of the Central African liana Ancistrocladus ealaensis (Ancistrocladaceae), a series of ten 7,8′-coupled naphthylisoquinoline alkaloids were isolated, comprising eight new compounds, named ealamines A–H (4a, 4b, 5–10), and two known ones, 6-O-demethylancistrobrevine A (11) and yaoundamine A (12), which had previously been found in related African Ancistrocladus species. Only one of the new compounds within this series, ealamine H (10), is a typical Ancistrocladaceae-type alkaloid, with 3S-configuration at C-3 and an oxygen function at C-6, whereas seven of the new alkaloids are the first 7,8′-linked “hybrid-type” naphthylisoquinoline alkaloids, i.e., 3R-configured and 6-oxygenated in the tetrahydroisoquinoline part. The discovery of such a broad series of 7,8′-coupled naphthyltetrahydroisoquinolines is unprecedented, because representatives of this subclass of alkaloids are normally found in Nature quite rarely. The stereostructures of the new ealamines were assigned by HRESIMS, 1D and 2D NMR, oxidative degradation, and experimental and quantum-chemical ECD investigations, and—in the case of ealamine A (4a)—also confirmed by X-ray diffraction analysis. Ealamines A–D exhibited distinct—and specific—antiplasmodial activities, and they displayed pronounced preferential cytotoxic effects toward PANC-1 human pancreatic cancer cells in nutrient-deprived medium, without causing toxicity under normal, nutrient-rich conditions, with ealamine C (5) as the most potent agent.}, author = {Tshitenge, Dieudonné Tshitenge and Bruhn, Torsten and Feineis, Doris and Schmidt, David and Mudogo, Virima and Kaiser, Marcel and Brun, Reto and Würthner, Frank and Awale, Suresh and Bringmann, Gerhard}, journal = {J. Nat. Prod.}, keywords = {myown}, month = 10, number = 11, pages = {3150-3164}, title = {Ealamines A–H, a Series of Naphthylisoquinolines with the Rare 7,8′-Coupling Site, from the Congolese Liana Ancistrocladus ealaensis, Targeting Pancreatic Cancer Cells}, volume = 82, year = 2019 }

  %0 Journal Article %1 noauthororeditor %A Tshitenge, Dieudonné Tshitenge %A Bruhn, Torsten %A Feineis, Doris %A Schmidt, David %A Mudogo, Virima %A Kaiser, Marcel %A Brun, Reto %A Würthner, Frank %A Awale, Suresh %A Bringmann, Gerhard %D 2019 %J J. Nat. Prod. %N 11 %P 3150-3164 %R 10.1021/acs.jnatprod.9b00755 %T Ealamines A–H, a Series of Naphthylisoquinolines with the Rare 7,8′-Coupling Site, from the Congolese Liana Ancistrocladus ealaensis, Targeting Pancreatic Cancer Cells %U https://pubs.acs.org/doi/abs/10.1021/acs.jnatprod.9b00755 %V 82 %X From the twigs and leaves of the Central African liana Ancistrocladus ealaensis (Ancistrocladaceae), a series of ten 7,8′-coupled naphthylisoquinoline alkaloids were isolated, comprising eight new compounds, named ealamines A–H (4a, 4b, 5–10), and two known ones, 6-O-demethylancistrobrevine A (11) and yaoundamine A (12), which had previously been found in related African Ancistrocladus species. Only one of the new compounds within this series, ealamine H (10), is a typical Ancistrocladaceae-type alkaloid, with 3S-configuration at C-3 and an oxygen function at C-6, whereas seven of the new alkaloids are the first 7,8′-linked “hybrid-type” naphthylisoquinoline alkaloids, i.e., 3R-configured and 6-oxygenated in the tetrahydroisoquinoline part. The discovery of such a broad series of 7,8′-coupled naphthyltetrahydroisoquinolines is unprecedented, because representatives of this subclass of alkaloids are normally found in Nature quite rarely. The stereostructures of the new ealamines were assigned by HRESIMS, 1D and 2D NMR, oxidative degradation, and experimental and quantum-chemical ECD investigations, and—in the case of ealamine A (4a)—also confirmed by X-ray diffraction analysis. Ealamines A–D exhibited distinct—and specific—antiplasmodial activities, and they displayed pronounced preferential cytotoxic effects toward PANC-1 human pancreatic cancer cells in nutrient-deprived medium, without causing toxicity under normal, nutrient-rich conditions, with ealamine C (5) as the most potent agent.
• Supramolecular polymerization and cyclization of dioxynaphthalene motif bridged bifunctional UPys: minor variations in the molecular skeleton and drastic differences in self-assembly. Xiao, Tangxin; Xu, Lixiang; Götz, Julian; Cheng, Ming; Würthner, Frank; Gu, Jiande; Feng, Xuejun; Li, Zheng-Yi; Sun, Xiao-Qiang; Wang, Leyong. In Mater. Chem. Front., 3(12), pp. 2738–2745. 2019.
  • [ Abstract ]
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  The relationship between molecular structure and macroscopic characteristics is a fundamental issue for materials design. Some minor changes in molecular structure may have a great impact on the molecular self-assembly process. Therefore, it is of interest to design new isomeric building blocks for supramolecular self-assembly, offering inspiration for the development of smart materials by supramolecular engineering. In this study, two dioxynaphthalene (DNP) group bridged bifunctional ureidopyrimidinone (UPy) monomers (DNP1 and DNP2) were synthesized. The chemical structures of the two isomers are very similar and the only difference is that DNP1 is 2,6-substituted and DNP2 is 1,5-substituted on the DNP motif. Interestingly, these two isomers exhibit completely different supramolecular self-assembly behaviors. Highly viscous supramolecular polymers were obtained in a concentrated solution of DNP1, while crystals based on highly stable cyclic monomers were precipitated from a concentrated solution of DNP2. Since DNP is an electron rich group, the host–guest behaviors of DNP1 and DNP2 with a blue-box were further studied, which also showed different ring-threading capabilities.

  @article{C9QM00595A, abstract = {The relationship between molecular structure and macroscopic characteristics is a fundamental issue for materials design. Some minor changes in molecular structure may have a great impact on the molecular self-assembly process. Therefore{,} it is of interest to design new isomeric building blocks for supramolecular self-assembly{,} offering inspiration for the development of smart materials by supramolecular engineering. In this study{,} two dioxynaphthalene (DNP) group bridged bifunctional ureidopyrimidinone (UPy) monomers (DNP1 and DNP2) were synthesized. The chemical structures of the two isomers are very similar and the only difference is that DNP1 is 2{,}6-substituted and DNP2 is 1{,}5-substituted on the DNP motif. Interestingly{,} these two isomers exhibit completely different supramolecular self-assembly behaviors. Highly viscous supramolecular polymers were obtained in a concentrated solution of DNP1{,} while crystals based on highly stable cyclic monomers were precipitated from a concentrated solution of DNP2. Since DNP is an electron rich group{,} the host–guest behaviors of DNP1 and DNP2 with a blue-box were further studied{,} which also showed different ring-threading capabilities.}, author = {Xiao, Tangxin and Xu, Lixiang and Götz, Julian and Cheng, Ming and Würthner, Frank and Gu, Jiande and Feng, Xuejun and Li, Zheng-Yi and Sun, Xiao-Qiang and Wang, Leyong}, journal = {Mater. Chem. Front.}, keywords = {myown}, month = 10, number = 12, pages = {2738-2745}, publisher = {The Royal Society of Chemistry}, title = {Supramolecular polymerization and cyclization of dioxynaphthalene motif bridged bifunctional UPys: minor variations in the molecular skeleton and drastic differences in self-assembly}, volume = 3, year = 2019 }

  %0 Journal Article %1 C9QM00595A %A Xiao, Tangxin %A Xu, Lixiang %A Götz, Julian %A Cheng, Ming %A Würthner, Frank %A Gu, Jiande %A Feng, Xuejun %A Li, Zheng-Yi %A Sun, Xiao-Qiang %A Wang, Leyong %D 2019 %I The Royal Society of Chemistry %J Mater. Chem. Front. %N 12 %P 2738-2745 %R 10.1039/C9QM00595A %T Supramolecular polymerization and cyclization of dioxynaphthalene motif bridged bifunctional UPys: minor variations in the molecular skeleton and drastic differences in self-assembly %U http://dx.doi.org/10.1039/C9QM00595A %V 3 %X The relationship between molecular structure and macroscopic characteristics is a fundamental issue for materials design. Some minor changes in molecular structure may have a great impact on the molecular self-assembly process. Therefore, it is of interest to design new isomeric building blocks for supramolecular self-assembly, offering inspiration for the development of smart materials by supramolecular engineering. In this study, two dioxynaphthalene (DNP) group bridged bifunctional ureidopyrimidinone (UPy) monomers (DNP1 and DNP2) were synthesized. The chemical structures of the two isomers are very similar and the only difference is that DNP1 is 2,6-substituted and DNP2 is 1,5-substituted on the DNP motif. Interestingly, these two isomers exhibit completely different supramolecular self-assembly behaviors. Highly viscous supramolecular polymers were obtained in a concentrated solution of DNP1, while crystals based on highly stable cyclic monomers were precipitated from a concentrated solution of DNP2. Since DNP is an electron rich group, the host–guest behaviors of DNP1 and DNP2 with a blue-box were further studied, which also showed different ring-threading capabilities.
• 1,1′-Bi(2-naphthol-4,5-dicarboximide)s: blue emissive axially chiral scaffolds with aggregation-enhanced emission properties. Chen, Meng-Ting; Zhang, Yang; Vysotsky, Myroslav O.; Lindner, Joachim O.; Li, Meng-Hua; Lin, Mei-Jin; Würthner, Frank. In Org. Chem. Front., 6(22), pp. 3731–3740. 2019.
  • [ Abstract ]
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  1,1′-Binaphthol (BINOL) is a versatile chiral reagent with widespread applications in asymmetric catalysis and fluorescent bio-sensing and imaging. However, unsubstituted BINOLs exhibit only weak and short-wavelength emission, limiting their scope for the latter applications. Herein, we report axially chiral 1,1′-bi(2-naphthol-4,5-dicarboximide)s which show two reversible reductions, bright blue light fluorescence with fluorescence quantum yields up to 0.67, and aggregation-enhanced emission characteristics. Single crystal X-ray analysis revealed an intriguing double helical supramolecular polymer motif formed by π–π stacking interactions between 2-naphthol-4,5-dicarboximide units. The enantiomers of racemic 1,1′-bi(2-naphthol-4,5-dicarboximide)s were resolved on chiral columns and studied by CD spectroscopy.

  @article{C9QO01090D, abstract = {1,1′-Binaphthol (BINOL) is a versatile chiral reagent with widespread applications in asymmetric catalysis and fluorescent bio-sensing and imaging. However, unsubstituted BINOLs exhibit only weak and short-wavelength emission, limiting their scope for the latter applications. Herein, we report axially chiral 1,1′-bi(2-naphthol-4,5-dicarboximide)s which show two reversible reductions, bright blue light fluorescence with fluorescence quantum yields up to 0.67, and aggregation-enhanced emission characteristics. Single crystal X-ray analysis revealed an intriguing double helical supramolecular polymer motif formed by π–π stacking interactions between 2-naphthol-4,5-dicarboximide units. The enantiomers of racemic 1,1′-bi(2-naphthol-4,5-dicarboximide)s were resolved on chiral columns and studied by CD spectroscopy.}, author = {Chen, Meng-Ting and Zhang, Yang and Vysotsky, Myroslav O. and Lindner, Joachim O. and Li, Meng-Hua and Lin, Mei-Jin and Würthner, Frank}, journal = {Org. Chem. Front.}, keywords = {myown}, month = 10, number = 22, pages = {3731-3740}, publisher = {The Royal Society of Chemistry}, title = {1,1′-Bi(2-naphthol-4,5-dicarboximide)s: blue emissive axially chiral scaffolds with aggregation-enhanced emission properties}, volume = 6, year = 2019 }

  %0 Journal Article %1 C9QO01090D %A Chen, Meng-Ting %A Zhang, Yang %A Vysotsky, Myroslav O. %A Lindner, Joachim O. %A Li, Meng-Hua %A Lin, Mei-Jin %A Würthner, Frank %D 2019 %I The Royal Society of Chemistry %J Org. Chem. Front. %N 22 %P 3731-3740 %R 10.1039/C9QO01090D %T 1,1′-Bi(2-naphthol-4,5-dicarboximide)s: blue emissive axially chiral scaffolds with aggregation-enhanced emission properties %U http://dx.doi.org/10.1039/C9QO01090D %V 6 %X 1,1′-Binaphthol (BINOL) is a versatile chiral reagent with widespread applications in asymmetric catalysis and fluorescent bio-sensing and imaging. However, unsubstituted BINOLs exhibit only weak and short-wavelength emission, limiting their scope for the latter applications. Herein, we report axially chiral 1,1′-bi(2-naphthol-4,5-dicarboximide)s which show two reversible reductions, bright blue light fluorescence with fluorescence quantum yields up to 0.67, and aggregation-enhanced emission characteristics. Single crystal X-ray analysis revealed an intriguing double helical supramolecular polymer motif formed by π–π stacking interactions between 2-naphthol-4,5-dicarboximide units. The enantiomers of racemic 1,1′-bi(2-naphthol-4,5-dicarboximide)s were resolved on chiral columns and studied by CD spectroscopy.
• Palladium-Catalyzed [3+2] Annulation of Naphthalimide Acceptors and Thiophene Donors. Shoyama, Kazutaka; Mahl, Magnus; M. A., Niyas; Ebert, Markus; Kachler, Valentin; Keck, Christoph; Würthner, Frank. In J. Org. Chem., 85(1), pp. 142–149. 2019.
  • [ Abstract ]
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  Donor–acceptor (D–A) dyes constitute one of the fundamental structural motifs of functional organic materials. In most cases, the donor and acceptor moieties are connected by a single bond, which could potentially be replaced by a fused aromatic ring to enhance the rigidity and conjugation of the dye moieties. However, there is still a lack of synthetic methodologies for such fused D–A systems. Here we report the synthesis of D–A and A–D–A dyes that possess fully annulated donor and acceptor moieties based on palladium (Pd)-catalyzed [3+2] annulation reaction between bromo-chloro-naphthalene dicarboximide and thiophene- and indole-based boronic esters. Thus, a series of fused D–A and A–D–A conjugated dyes were synthesized in good to high yields by a cascade of Pd-catalyzed Suzuki–Miyaura cross-coupling and direct arylation reactions. The newly synthesized fused D–A and A–D–A dyes with one or two naphthalimide units fused to five-membered electron-rich heterocyles were systematically investigated by ultraviolet–visible spectroscopy, cyclic and square wave voltammetry, and density functional theory calculations. These dyes possess desirable optical and electrochemical properties for application as organic electronic materials as they show absorption up to the near-infrared region, undergo up to 4-fold reduction processes, and have low-lying LUMO energy levels down to −3.62 eV.

  @article{noauthororeditor, abstract = {Donor–acceptor (D–A) dyes constitute one of the fundamental structural motifs of functional organic materials. In most cases, the donor and acceptor moieties are connected by a single bond, which could potentially be replaced by a fused aromatic ring to enhance the rigidity and conjugation of the dye moieties. However, there is still a lack of synthetic methodologies for such fused D–A systems. Here we report the synthesis of D–A and A–D–A dyes that possess fully annulated donor and acceptor moieties based on palladium (Pd)-catalyzed [3+2] annulation reaction between bromo-chloro-naphthalene dicarboximide and thiophene- and indole-based boronic esters. Thus, a series of fused D–A and A–D–A conjugated dyes were synthesized in good to high yields by a cascade of Pd-catalyzed Suzuki–Miyaura cross-coupling and direct arylation reactions. The newly synthesized fused D–A and A–D–A dyes with one or two naphthalimide units fused to five-membered electron-rich heterocyles were systematically investigated by ultraviolet–visible spectroscopy, cyclic and square wave voltammetry, and density functional theory calculations. These dyes possess desirable optical and electrochemical properties for application as organic electronic materials as they show absorption up to the near-infrared region, undergo up to 4-fold reduction processes, and have low-lying LUMO energy levels down to −3.62 eV.}, author = {Shoyama, Kazutaka and Mahl, Magnus and M. A., Niyas and Ebert, Markus and Kachler, Valentin and Keck, Christoph and Würthner, Frank}, journal = {J. Org. Chem.}, keywords = {myown}, month = 11, number = 1, pages = {142-149}, title = {Palladium-Catalyzed [3+2] Annulation of Naphthalimide Acceptors and Thiophene Donors}, volume = 85, year = 2019 }

  %0 Journal Article %1 noauthororeditor %A Shoyama, Kazutaka %A Mahl, Magnus %A M. A., Niyas %A Ebert, Markus %A Kachler, Valentin %A Keck, Christoph %A Würthner, Frank %D 2019 %J J. Org. Chem. %N 1 %P 142-149 %R 10.1021/acs.joc.9b02372 %T Palladium-Catalyzed [3+2] Annulation of Naphthalimide Acceptors and Thiophene Donors %U https://pubs.acs.org/doi/abs/10.1021/acs.joc.9b02372 %V 85 %X Donor–acceptor (D–A) dyes constitute one of the fundamental structural motifs of functional organic materials. In most cases, the donor and acceptor moieties are connected by a single bond, which could potentially be replaced by a fused aromatic ring to enhance the rigidity and conjugation of the dye moieties. However, there is still a lack of synthetic methodologies for such fused D–A systems. Here we report the synthesis of D–A and A–D–A dyes that possess fully annulated donor and acceptor moieties based on palladium (Pd)-catalyzed [3+2] annulation reaction between bromo-chloro-naphthalene dicarboximide and thiophene- and indole-based boronic esters. Thus, a series of fused D–A and A–D–A conjugated dyes were synthesized in good to high yields by a cascade of Pd-catalyzed Suzuki–Miyaura cross-coupling and direct arylation reactions. The newly synthesized fused D–A and A–D–A dyes with one or two naphthalimide units fused to five-membered electron-rich heterocyles were systematically investigated by ultraviolet–visible spectroscopy, cyclic and square wave voltammetry, and density functional theory calculations. These dyes possess desirable optical and electrochemical properties for application as organic electronic materials as they show absorption up to the near-infrared region, undergo up to 4-fold reduction processes, and have low-lying LUMO energy levels down to −3.62 eV.
• A Water-Soluble Perylene Bisimide Cyclophane as a Molecular Probe for the Recognition of Aromatic Alkaloids. Sapotta, Meike; Hofmann, Anja; Bialas, David; Würthner, Frank. In Angew. Chem. Int. Ed., 58, pp. 3516 –3520. 2019.
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  Herein, we report a water‐soluble macrocyclic host based on perylene bisimide (PBI) chromophores that recognizes natural aromatic alkaloids in aqueous media by intercalating them into its hydrophobic cavity. The host–guest binding properties of our newly designed receptor with several alkaloids were studied by UV/Vis and fluorescence titration experiments as the optical properties of the chromophoric host change significantly upon complexation of guests. Structural information on the host–guest complexes was obtained by 1D and 2D NMR spectroscopy and molecular modelling. Our studies reveal a structure–binding property relationship for a series of structurally diverse aromatic alkaloids with the new receptor and higher binding affinity for the class of harmala alkaloids. To our knowledge, this is the first example of a chromophoric macrocyclic host employed as a molecular probe for the recognition of aromatic alkaloids.

  @article{sapotta2019awatersoluble, abstract = {Herein, we report a water‐soluble macrocyclic host based on perylene bisimide (PBI) chromophores that recognizes natural aromatic alkaloids in aqueous media by intercalating them into its hydrophobic cavity. The host–guest binding properties of our newly designed receptor with several alkaloids were studied by UV/Vis and fluorescence titration experiments as the optical properties of the chromophoric host change significantly upon complexation of guests. Structural information on the host–guest complexes was obtained by 1D and 2D NMR spectroscopy and molecular modelling. Our studies reveal a structure–binding property relationship for a series of structurally diverse aromatic alkaloids with the new receptor and higher binding affinity for the class of harmala alkaloids. To our knowledge, this is the first example of a chromophoric macrocyclic host employed as a molecular probe for the recognition of aromatic alkaloids.}, author = {Sapotta, Meike and Hofmann, Anja and Bialas, David and Würthner, Frank}, journal = {Angew. Chem. Int. Ed.}, keywords = {organic}, month = {03}, pages = {3516 –3520}, title = {A Water-Soluble Perylene Bisimide Cyclophane as a Molecular Probe for the Recognition of Aromatic Alkaloids}, volume = 58, year = 2019 }

  %0 Journal Article %1 sapotta2019awatersoluble %A Sapotta, Meike %A Hofmann, Anja %A Bialas, David %A Würthner, Frank %D 2019 %J Angew. Chem. Int. Ed. %P 3516 –3520 %R 10.1002/anie.201813559 %T A Water-Soluble Perylene Bisimide Cyclophane as a Molecular Probe for the Recognition of Aromatic Alkaloids %V 58 %X Herein, we report a water‐soluble macrocyclic host based on perylene bisimide (PBI) chromophores that recognizes natural aromatic alkaloids in aqueous media by intercalating them into its hydrophobic cavity. The host–guest binding properties of our newly designed receptor with several alkaloids were studied by UV/Vis and fluorescence titration experiments as the optical properties of the chromophoric host change significantly upon complexation of guests. Structural information on the host–guest complexes was obtained by 1D and 2D NMR spectroscopy and molecular modelling. Our studies reveal a structure–binding property relationship for a series of structurally diverse aromatic alkaloids with the new receptor and higher binding affinity for the class of harmala alkaloids. To our knowledge, this is the first example of a chromophoric macrocyclic host employed as a molecular probe for the recognition of aromatic alkaloids.
• Tunable Low-LUMO Boron-Doped Polycyclic Aromatic Hydrocarbons by General One-Pot C–H Borylations. Farrell, Jeffrey; Mützel, Carina; Bialas, David; Rudolf, Maximilian; Menekse, Kaan; Krause, Ana-Maria; Stolte, Matthias; Würthner, Frank. In J. Am. Chem. Soc, 141(22), pp. 9096–9104. 2019.
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  Boron-doping has long been recognized as a promising LUMO energy-lowering modification of graphene and related polycyclic aromatic hydrocarbons (PAHs). Unfortunately, synthetic difficulties have been a significant bottleneck for the understanding, optimization, and application of precisely boron-doped PAHs for optoelectronic purposes. Herein, a facile one-pot hydroboration electrophilic borylation cascade/dehydrogenation approach from simple alkene precursors is coupled with postsynthetic B-substitution to give access to ten ambient-stable core- and periphery-tuned boron-doped PAHs. These include large hitherto unknown doubly boron-doped analogues of anthanthrene and triangulene. Crystallographic, optical, electrochemical, and computational studies were performed to clarify the effect of boron-doped PAH shape, size, and structure on optoelectronic properties. Our molecular tuning allowed the synthesis of molecules exhibiting visible-range absorption, near-unity fluorescence quantum yields, and, to our knowledge, the most facile electrochemical reductions of any reported ambient-stable boron-doped PAHs (corresponding to LUMO energy levels as low as fullerenes). Finally, our study describes the first implementation of a precise three-coordinate boron-substituted PAH as an acceptor material in organic solar cells with power conversion efficiencies (PCEs) of up to 3%.

  @article{noauthororeditor, abstract = {Boron-doping has long been recognized as a promising LUMO energy-lowering modification of graphene and related polycyclic aromatic hydrocarbons (PAHs). Unfortunately, synthetic difficulties have been a significant bottleneck for the understanding, optimization, and application of precisely boron-doped PAHs for optoelectronic purposes. Herein, a facile one-pot hydroboration electrophilic borylation cascade/dehydrogenation approach from simple alkene precursors is coupled with postsynthetic B-substitution to give access to ten ambient-stable core- and periphery-tuned boron-doped PAHs. These include large hitherto unknown doubly boron-doped analogues of anthanthrene and triangulene. Crystallographic, optical, electrochemical, and computational studies were performed to clarify the effect of boron-doped PAH shape, size, and structure on optoelectronic properties. Our molecular tuning allowed the synthesis of molecules exhibiting visible-range absorption, near-unity fluorescence quantum yields, and, to our knowledge, the most facile electrochemical reductions of any reported ambient-stable boron-doped PAHs (corresponding to LUMO energy levels as low as fullerenes). Finally, our study describes the first implementation of a precise three-coordinate boron-substituted PAH as an acceptor material in organic solar cells with power conversion efficiencies (PCEs) of up to 3%.}, author = {Farrell, Jeffrey and Mützel, Carina and Bialas, David and Rudolf, Maximilian and Menekse, Kaan and Krause, Ana-Maria and Stolte, Matthias and Würthner, Frank}, journal = {J. Am. Chem. Soc}, keywords = {myown}, month = {05}, number = 22, pages = {9096-9104}, title = {Tunable Low-LUMO Boron-Doped Polycyclic Aromatic Hydrocarbons by General One-Pot C–H Borylations}, volume = 141, year = 2019 }

  %0 Journal Article %1 noauthororeditor %A Farrell, Jeffrey %A Mützel, Carina %A Bialas, David %A Rudolf, Maximilian %A Menekse, Kaan %A Krause, Ana-Maria %A Stolte, Matthias %A Würthner, Frank %D 2019 %J J. Am. Chem. Soc %N 22 %P 9096-9104 %R 10.1021/jacs.9b04675 %T Tunable Low-LUMO Boron-Doped Polycyclic Aromatic Hydrocarbons by General One-Pot C–H Borylations %U https://pubs.acs.org/doi/abs/10.1021/jacs.9b04675 %V 141 %X Boron-doping has long been recognized as a promising LUMO energy-lowering modification of graphene and related polycyclic aromatic hydrocarbons (PAHs). Unfortunately, synthetic difficulties have been a significant bottleneck for the understanding, optimization, and application of precisely boron-doped PAHs for optoelectronic purposes. Herein, a facile one-pot hydroboration electrophilic borylation cascade/dehydrogenation approach from simple alkene precursors is coupled with postsynthetic B-substitution to give access to ten ambient-stable core- and periphery-tuned boron-doped PAHs. These include large hitherto unknown doubly boron-doped analogues of anthanthrene and triangulene. Crystallographic, optical, electrochemical, and computational studies were performed to clarify the effect of boron-doped PAH shape, size, and structure on optoelectronic properties. Our molecular tuning allowed the synthesis of molecules exhibiting visible-range absorption, near-unity fluorescence quantum yields, and, to our knowledge, the most facile electrochemical reductions of any reported ambient-stable boron-doped PAHs (corresponding to LUMO energy levels as low as fullerenes). Finally, our study describes the first implementation of a precise three-coordinate boron-substituted PAH as an acceptor material in organic solar cells with power conversion efficiencies (PCEs) of up to 3%.
• A Highly Warped Heptagon-Containing sp² Carbon Scaffold via Vinylnaphthyl π-Extension. Farrell, Jeffrey M.; Grande, Vincenzo; Schmidt, David; Würthner, Frank. In Angew. Chem. Int. Ed., 58(46), pp. 16504 –16507. 2019.
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  Abstract: A new strategy is demonstrated for the synthesis of warped, negatively curved, all-sp2-carbon p-scaffolds. Multifold C@C coupling reactions are used to transform a polyaromatic borinic acid into a saddle-shaped polyaromatic hydrocarbon (2) bearing two heptagonal rings. Notably, this Schwarzite substructure is synthesized in only two steps from an unfunctionalized alkene. A highly warped structure of 2 was revealed by X-ray crystallographic studies and pronounced flexibility of this p-scaffold was ascertained by experimental and computational studies. Compound 2 exhibits excellent solubility, visible range absorption and fluorescence, and readily undergoes two reversible one-electron oxidations at mild potentials.

  @article{Farrell_2019, abstract = {Abstract: A new strategy is demonstrated for the synthesis of warped, negatively curved, all-sp2-carbon p-scaffolds. Multifold C@C coupling reactions are used to transform a polyaromatic borinic acid into a saddle-shaped polyaromatic hydrocarbon (2) bearing two heptagonal rings. Notably, this Schwarzite substructure is synthesized in only two steps from an unfunctionalized alkene. A highly warped structure of 2 was revealed by X-ray crystallographic studies and pronounced flexibility of this p-scaffold was ascertained by experimental and computational studies. Compound 2 exhibits excellent solubility, visible range absorption and fluorescence, and readily undergoes two reversible one-electron oxidations at mild potentials.}, author = {Farrell, Jeffrey M. and Grande, Vincenzo and Schmidt, David and Würthner, Frank}, journal = {Angew. Chem. Int. Ed.}, keywords = {myown}, month = {09}, number = 46, pages = {16504 –16507}, publisher = {Wiley}, title = {A Highly Warped Heptagon-Containing sp² Carbon Scaffold via Vinylnaphthyl π-Extension}, volume = 58, year = 2019 }

  %0 Journal Article %1 Farrell_2019 %A Farrell, Jeffrey M. %A Grande, Vincenzo %A Schmidt, David %A Würthner, Frank %D 2019 %I Wiley %J Angew. Chem. Int. Ed. %N 46 %P 16504 –16507 %R 10.1002/anie.201909975 %T A Highly Warped Heptagon-Containing sp² Carbon Scaffold via Vinylnaphthyl π-Extension %U https://onlinelibrary.wiley.com/doi/full/10.1002/anie.201909975 %V 58 %X Abstract: A new strategy is demonstrated for the synthesis of warped, negatively curved, all-sp2-carbon p-scaffolds. Multifold C@C coupling reactions are used to transform a polyaromatic borinic acid into a saddle-shaped polyaromatic hydrocarbon (2) bearing two heptagonal rings. Notably, this Schwarzite substructure is synthesized in only two steps from an unfunctionalized alkene. A highly warped structure of 2 was revealed by X-ray crystallographic studies and pronounced flexibility of this p-scaffold was ascertained by experimental and computational studies. Compound 2 exhibits excellent solubility, visible range absorption and fluorescence, and readily undergoes two reversible one-electron oxidations at mild potentials.
• Linking two worlds in polymer chemistry: The influence of block uniformity and dispersity in amphiphilic block copolypeptoids on their self‐assembly. Gangloff, Niklas; Höferth, Marcel; Stepanenko, Vladimir; Sochor, Benedikt; Schummer, Bernhard; Nickel, Joachim; Walles, Heike; Hanke, Randolf; Würthner, Frank; Zuckermann, Ronald N.; Luxenhofer, Robert. In Biopolymers, 110(4), p. e23259. 2019.
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  The self‐assembly of block copolymers has captured the interest of scientists for many decades because it can induce ordered structures and help to imitate complex structures found in nature. In contrast to proteins, nature's most functional hierarchical structures, conventional polymers are disperse in their length distribution. Here, we synthesized hydrophilic and hydrophobic polypeptoids via solid‐phase synthesis (uniform) and ring‐opening polymerization (disperse). Differential scanning calorimetry measurements showed that the uniform hydrophobic peptoids converge to a maximum of the melting temperature at a much lower chain length than their disperse analogs, showing that not only the chain length but also the dispersity has a considerable impact on the thermal properties of those homopolymers. These homopolymers were then coupled to yield amphiphilic block copolypeptoids. SAXS and AFM measurements confirm that the dispersity plays a major role in microphase separation of these macromolecules, and it appears that uniform hydrophobic blocks form more ordered structures.

  @article{gangloff2019linking, abstract = {The self‐assembly of block copolymers has captured the interest of scientists for many decades because it can induce ordered structures and help to imitate complex structures found in nature. In contrast to proteins, nature's most functional hierarchical structures, conventional polymers are disperse in their length distribution. Here, we synthesized hydrophilic and hydrophobic polypeptoids via solid‐phase synthesis (uniform) and ring‐opening polymerization (disperse). Differential scanning calorimetry measurements showed that the uniform hydrophobic peptoids converge to a maximum of the melting temperature at a much lower chain length than their disperse analogs, showing that not only the chain length but also the dispersity has a considerable impact on the thermal properties of those homopolymers. These homopolymers were then coupled to yield amphiphilic block copolypeptoids. SAXS and AFM measurements confirm that the dispersity plays a major role in microphase separation of these macromolecules, and it appears that uniform hydrophobic blocks form more ordered structures.}, author = {Gangloff, Niklas and Höferth, Marcel and Stepanenko, Vladimir and Sochor, Benedikt and Schummer, Bernhard and Nickel, Joachim and Walles, Heike and Hanke, Randolf and Würthner, Frank and Zuckermann, Ronald N. and Luxenhofer, Robert}, journal = {Biopolymers}, keywords = {dispersy}, month = {04}, number = 4, pages = {e23259}, title = {Linking two worlds in polymer chemistry: The influence of block uniformity and dispersity in amphiphilic block copolypeptoids on their self‐assembly}, volume = 110, year = 2019 }

  %0 Journal Article %1 gangloff2019linking %A Gangloff, Niklas %A Höferth, Marcel %A Stepanenko, Vladimir %A Sochor, Benedikt %A Schummer, Bernhard %A Nickel, Joachim %A Walles, Heike %A Hanke, Randolf %A Würthner, Frank %A Zuckermann, Ronald N. %A Luxenhofer, Robert %D 2019 %J Biopolymers %N 4 %P e23259 %R 10.1002/bip.23259 %T Linking two worlds in polymer chemistry: The influence of block uniformity and dispersity in amphiphilic block copolypeptoids on their self‐assembly %V 110 %X The self‐assembly of block copolymers has captured the interest of scientists for many decades because it can induce ordered structures and help to imitate complex structures found in nature. In contrast to proteins, nature's most functional hierarchical structures, conventional polymers are disperse in their length distribution. Here, we synthesized hydrophilic and hydrophobic polypeptoids via solid‐phase synthesis (uniform) and ring‐opening polymerization (disperse). Differential scanning calorimetry measurements showed that the uniform hydrophobic peptoids converge to a maximum of the melting temperature at a much lower chain length than their disperse analogs, showing that not only the chain length but also the dispersity has a considerable impact on the thermal properties of those homopolymers. These homopolymers were then coupled to yield amphiphilic block copolypeptoids. SAXS and AFM measurements confirm that the dispersity plays a major role in microphase separation of these macromolecules, and it appears that uniform hydrophobic blocks form more ordered structures.
• Defined Merocyanine Dye Stacks from a Dimer up to an Octamer by Spacer-Encoded Self-Assembly Approach. Kirchner, Eva; Bialas, David; Fennel, Franziska; Grüne, Matthias; Würthner, Frank. In J. Am. Chem. Soc., 141(18), pp. 7428–7438. 2019.
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  A series of well-defined chromophore stacks is obtained upon self-assembly of merocyanine and bis(merocyanine) dyes in nonpolar solvents. Careful design of the spacer moieties linking the dipolar chromophores within the bis(merocyanine) dyes allows one to direct the dipole–dipole interaction driven aggregation into stacks of desired size from dimer up to octamer. The spacer-encoded self-assembly process was investigated by UV/vis absorption spectroscopy showing an increase of the hypsochromic shift with increasing stack size. The structure of the largest aggregate comprising eight chromophores was analyzed by 1D and 2D nuclear magnetic resonance spectroscopic studies revealing a perfectly interdigitated centrosymmetric organization of the dipolar dyes and concomitant annihilation of the ground state dipole moment is observed in the UV/vis absorption spectra. This unprecedented series of dye stacks from dimer to octamer enabled a systematic study of the optical absorption properties in dependence of the stack size disclosing that the absorption features can be rationalized by molecular exciton theory. Our results show that the noncovalent synthesis approach based on dipolar aggregation is suitable for the design of well-defined dye aggregates of specific size, allowing in-depth studies to manifest structure–property relationships.

  @article{Kirchner_2019, abstract = {A series of well-defined chromophore stacks is obtained upon self-assembly of merocyanine and bis(merocyanine) dyes in nonpolar solvents. Careful design of the spacer moieties linking the dipolar chromophores within the bis(merocyanine) dyes allows one to direct the dipole–dipole interaction driven aggregation into stacks of desired size from dimer up to octamer. The spacer-encoded self-assembly process was investigated by UV/vis absorption spectroscopy showing an increase of the hypsochromic shift with increasing stack size. The structure of the largest aggregate comprising eight chromophores was analyzed by 1D and 2D nuclear magnetic resonance spectroscopic studies revealing a perfectly interdigitated centrosymmetric organization of the dipolar dyes and concomitant annihilation of the ground state dipole moment is observed in the UV/vis absorption spectra. This unprecedented series of dye stacks from dimer to octamer enabled a systematic study of the optical absorption properties in dependence of the stack size disclosing that the absorption features can be rationalized by molecular exciton theory. Our results show that the noncovalent synthesis approach based on dipolar aggregation is suitable for the design of well-defined dye aggregates of specific size, allowing in-depth studies to manifest structure–property relationships.}, author = {Kirchner, Eva and Bialas, David and Fennel, Franziska and Grüne, Matthias and Würthner, Frank}, journal = {J. Am. Chem. Soc.}, keywords = {myown}, month = {04}, number = 18, pages = {7428–7438}, publisher = {American Chemical Society ({ACS})}, title = {Defined Merocyanine Dye Stacks from a Dimer up to an Octamer by Spacer-Encoded Self-Assembly Approach.}, volume = 141, year = 2019 }

  %0 Journal Article %1 Kirchner_2019 %A Kirchner, Eva %A Bialas, David %A Fennel, Franziska %A Grüne, Matthias %A Würthner, Frank %D 2019 %I American Chemical Society (ACS) %J J. Am. Chem. Soc. %N 18 %P 7428--7438 %R 10.1021/jacs.9b01835 %T Defined Merocyanine Dye Stacks from a Dimer up to an Octamer by Spacer-Encoded Self-Assembly Approach. %U https://doi.org/10.1021%2Fjacs.9b01835 %V 141 %X A series of well-defined chromophore stacks is obtained upon self-assembly of merocyanine and bis(merocyanine) dyes in nonpolar solvents. Careful design of the spacer moieties linking the dipolar chromophores within the bis(merocyanine) dyes allows one to direct the dipole–dipole interaction driven aggregation into stacks of desired size from dimer up to octamer. The spacer-encoded self-assembly process was investigated by UV/vis absorption spectroscopy showing an increase of the hypsochromic shift with increasing stack size. The structure of the largest aggregate comprising eight chromophores was analyzed by 1D and 2D nuclear magnetic resonance spectroscopic studies revealing a perfectly interdigitated centrosymmetric organization of the dipolar dyes and concomitant annihilation of the ground state dipole moment is observed in the UV/vis absorption spectra. This unprecedented series of dye stacks from dimer to octamer enabled a systematic study of the optical absorption properties in dependence of the stack size disclosing that the absorption features can be rationalized by molecular exciton theory. Our results show that the noncovalent synthesis approach based on dipolar aggregation is suitable for the design of well-defined dye aggregates of specific size, allowing in-depth studies to manifest structure–property relationships.
• Organic Electronics: Ultranarrow Bandwidth Organic Photodiodes by Exchange Narrowing in Merocyanine H‐ and J‐Aggregate Excitonic Systems. Liess, Andreas; Arjona‐Esteban, Alhama; Kudzus, Astrid; Albert, Julius; Krause, Ana‐Maria; Lv, Aifeng; Stolte, Matthias; Meerholz, Klaus; Würthner, Frank. In Advanced Functional Materials, 29(21), pp. 1805058 (1–9). 2019.
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  Ultranarrowband organic photodiodes (OPDs) are demonstrated for thin film solid state materials composed of tightly packed dipolar merocyanine dyes. For these dyes the packing arrangement can be controlled by the bulkiness of the donor substituent, leading to either strong H‐ or strong J‐type exciton coupling in the interesting blue (H‐aggregate) and NIR (J‐aggregate) spectral ranges. Both bands are shown to arise from one single exciton band according to fluorescence measurements and are not just a mere consequence of different polymorphs within the same thin film. By fabrication of organic thin‐film transistors, these dyes are demonstrated to exhibit hole transport behavior in spin‐coated thin films. Moreover, when used as organic photodiodes in planar heterojunctions with C60 fullerene, they show wavelength‐selective photocurrents in the solid state with maximum external quantum efficiencies of up to 11% and ultranarrow bandwidths down to 30 nm. Thereby, narrowing the linewidths of optoelectronic functional materials by exciton coupling provides a powerful approach to produce ultranarrowband organic photodiodes.

  @article{liess2019organic, abstract = {Ultranarrowband organic photodiodes (OPDs) are demonstrated for thin film solid state materials composed of tightly packed dipolar merocyanine dyes. For these dyes the packing arrangement can be controlled by the bulkiness of the donor substituent, leading to either strong H‐ or strong J‐type exciton coupling in the interesting blue (H‐aggregate) and NIR (J‐aggregate) spectral ranges. Both bands are shown to arise from one single exciton band according to fluorescence measurements and are not just a mere consequence of different polymorphs within the same thin film. By fabrication of organic thin‐film transistors, these dyes are demonstrated to exhibit hole transport behavior in spin‐coated thin films. Moreover, when used as organic photodiodes in planar heterojunctions with C60 fullerene, they show wavelength‐selective photocurrents in the solid state with maximum external quantum efficiencies of up to 11% and ultranarrow bandwidths down to 30 nm. Thereby, narrowing the linewidths of optoelectronic functional materials by exciton coupling provides a powerful approach to produce ultranarrowband organic photodiodes.}, author = {Liess, Andreas and Arjona‐Esteban, Alhama and Kudzus, Astrid and Albert, Julius and Krause, Ana‐Maria and Lv, Aifeng and Stolte, Matthias and Meerholz, Klaus and Würthner, Frank}, journal = {Advanced Functional Materials}, keywords = {organic}, month = {05}, number = 21, pages = {1805058 (1-9)}, title = {Organic Electronics: Ultranarrow Bandwidth Organic Photodiodes by Exchange Narrowing in Merocyanine H‐ and J‐Aggregate Excitonic Systems}, volume = 29, year = 2019 }

  %0 Journal Article %1 liess2019organic %A Liess, Andreas %A Arjona‐Esteban, Alhama %A Kudzus, Astrid %A Albert, Julius %A Krause, Ana‐Maria %A Lv, Aifeng %A Stolte, Matthias %A Meerholz, Klaus %A Würthner, Frank %D 2019 %J Advanced Functional Materials %N 21 %P 1805058 (1-9) %R 10.1002/adfm.201970144 %T Organic Electronics: Ultranarrow Bandwidth Organic Photodiodes by Exchange Narrowing in Merocyanine H‐ and J‐Aggregate Excitonic Systems %U https://doi.org/10.1002/adfm.201970144 %V 29 %X Ultranarrowband organic photodiodes (OPDs) are demonstrated for thin film solid state materials composed of tightly packed dipolar merocyanine dyes. For these dyes the packing arrangement can be controlled by the bulkiness of the donor substituent, leading to either strong H‐ or strong J‐type exciton coupling in the interesting blue (H‐aggregate) and NIR (J‐aggregate) spectral ranges. Both bands are shown to arise from one single exciton band according to fluorescence measurements and are not just a mere consequence of different polymorphs within the same thin film. By fabrication of organic thin‐film transistors, these dyes are demonstrated to exhibit hole transport behavior in spin‐coated thin films. Moreover, when used as organic photodiodes in planar heterojunctions with C60 fullerene, they show wavelength‐selective photocurrents in the solid state with maximum external quantum efficiencies of up to 11% and ultranarrow bandwidths down to 30 nm. Thereby, narrowing the linewidths of optoelectronic functional materials by exciton coupling provides a powerful approach to produce ultranarrowband organic photodiodes.
• Thermodynamic insights into the entropically driven self-assembly of amphiphilic dyes in water. Syamala, Pradeep P. N.; Soberats, Bartolome; Görl, Daniel; Gekle, Stephan; Würthner, Frank. In Chem. Sci., 10(40), pp. 9358–9366. 2019.
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  Self-assembly of amphiphilic dyes and π-systems are more difficult to understand and to control in water compared to organic solvents due to the hydrophobic effect. Herein, we elucidate in detail the self-assembly of a series of archetype bolaamphiphiles bearing a naphthalene bisimide (NBI) π-core with appended oligoethylene glycol (OEG) dendrons of different size. By utilizing temperature-dependent UV-vis spectroscopy and isothermal titration calorimetry (ITC), we have dissected the enthalpic and entropic parameters pertaining to the molecules' self-assembly. All investigated compounds show an enthalpically disfavored aggregation process leading to aggregate growth and eventually precipitation at elevated temperature, which is attributed to the dehydration of oligoethylene glycol units and their concomitant conformational changes. Back-folded conformation of the side chains plays a major role, as revealed by molecular dynamics (MD) and two dimensional NMR (2D NMR) studies, in directing the association. The sterical effect imparted by the jacketing of monomers and dimers also changes the aggregation mechanism from isodesmic to weakly anti-cooperative.

  @article{C9SC03103K, abstract = {Self-assembly of amphiphilic dyes and π-systems are more difficult to understand and to control in water compared to organic solvents due to the hydrophobic effect. Herein{,} we elucidate in detail the self-assembly of a series of archetype bolaamphiphiles bearing a naphthalene bisimide (NBI) π-core with appended oligoethylene glycol (OEG) dendrons of different size. By utilizing temperature-dependent UV-vis spectroscopy and isothermal titration calorimetry (ITC){,} we have dissected the enthalpic and entropic parameters pertaining to the molecules{'} self-assembly. All investigated compounds show an enthalpically disfavored aggregation process leading to aggregate growth and eventually precipitation at elevated temperature{,} which is attributed to the dehydration of oligoethylene glycol units and their concomitant conformational changes. Back-folded conformation of the side chains plays a major role{,} as revealed by molecular dynamics (MD) and two dimensional NMR (2D NMR) studies{,} in directing the association. The sterical effect imparted by the jacketing of monomers and dimers also changes the aggregation mechanism from isodesmic to weakly anti-cooperative.}, author = {Syamala, Pradeep P. N. and Soberats, Bartolome and Görl, Daniel and Gekle, Stephan and Würthner, Frank}, journal = {Chem. Sci.}, keywords = {myown}, month = {08}, number = 40, pages = {9358-9366}, publisher = {The Royal Society of Chemistry}, title = {Thermodynamic insights into the entropically driven self-assembly of amphiphilic dyes in water}, volume = 10, year = 2019 }

  %0 Journal Article %1 C9SC03103K %A Syamala, Pradeep P. N. %A Soberats, Bartolome %A Görl, Daniel %A Gekle, Stephan %A Würthner, Frank %D 2019 %I The Royal Society of Chemistry %J Chem. Sci. %N 40 %P 9358-9366 %R 10.1039/C9SC03103K %T Thermodynamic insights into the entropically driven self-assembly of amphiphilic dyes in water %U http://dx.doi.org/10.1039/C9SC03103K %V 10 %X Self-assembly of amphiphilic dyes and π-systems are more difficult to understand and to control in water compared to organic solvents due to the hydrophobic effect. Herein, we elucidate in detail the self-assembly of a series of archetype bolaamphiphiles bearing a naphthalene bisimide (NBI) π-core with appended oligoethylene glycol (OEG) dendrons of different size. By utilizing temperature-dependent UV-vis spectroscopy and isothermal titration calorimetry (ITC), we have dissected the enthalpic and entropic parameters pertaining to the molecules' self-assembly. All investigated compounds show an enthalpically disfavored aggregation process leading to aggregate growth and eventually precipitation at elevated temperature, which is attributed to the dehydration of oligoethylene glycol units and their concomitant conformational changes. Back-folded conformation of the side chains plays a major role, as revealed by molecular dynamics (MD) and two dimensional NMR (2D NMR) studies, in directing the association. The sterical effect imparted by the jacketing of monomers and dimers also changes the aggregation mechanism from isodesmic to weakly anti-cooperative.

• Impact of 2-Ethylhexyl Stereoisomers on the Electrical Performance of Single-Crystal Field-Effect Transistors. He, Tao; Leowanawat, Pawaret; Burschka, Christian; Stepanenko, Vladimir; Stolte, Matthias; Würthner, Frank. In Advanced Materials, 30, pp. 1804032–1804039. 2018.
  • [ Abstract ]
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  Many organic semiconductors (OSCs) inherit chiral alkyl chains, which ensure the desirable high solubility for solution‐processing but may also lead to disorder, inhomogeneous film‐formation, as well as interfacial defects due to the presence of mixtures of stereoisomers or diastereomers, which impair their peak performance. Here, single‐crystal field‐effect transistors (SCFETs) of a diketopyrrolopyrrole‐based organic semiconductor with chiral 2‐ethylhexyl substituents by sublimation in air and organic ribbon mask method are fabricated. Devices of the mesomer (R/S), both enantiomers (R/R, S/S), as well as mixtures of these three stereoisomers measured under ambient conditions exhibit all appreciable p‐channel charge carrier mobilities of > 0.1 cm2 V−1 s−1 despite different packing arrangement in the R/S, R/R (or S/S), and racemate crystal structures. These results suggest a surprising tolerance for isomeric impurities. The highest literature‐reported p‐channel mobility so far for a diketopyrrolopyrrole‐based OSC of 3.4 cm2 V−1 s−1 (Ion/Ioff of 1 × 106) is, however, only obtained for the pure R/S mesomer, illustrating the inherent potential of stereochemical purity. These results on SCFETs are further substantiated by studies on organic thin‐film transistors (OTFTs) of pure and mixed thin films of the different stereoisomers.

  @article{he2018impact, abstract = {Many organic semiconductors (OSCs) inherit chiral alkyl chains, which ensure the desirable high solubility for solution‐processing but may also lead to disorder, inhomogeneous film‐formation, as well as interfacial defects due to the presence of mixtures of stereoisomers or diastereomers, which impair their peak performance. Here, single‐crystal field‐effect transistors (SCFETs) of a diketopyrrolopyrrole‐based organic semiconductor with chiral 2‐ethylhexyl substituents by sublimation in air and organic ribbon mask method are fabricated. Devices of the mesomer (R/S), both enantiomers (R/R, S/S), as well as mixtures of these three stereoisomers measured under ambient conditions exhibit all appreciable p‐channel charge carrier mobilities of > 0.1 cm2 V−1 s−1 despite different packing arrangement in the R/S, R/R (or S/S), and racemate crystal structures. These results suggest a surprising tolerance for isomeric impurities. The highest literature‐reported p‐channel mobility so far for a diketopyrrolopyrrole‐based OSC of 3.4 cm2 V−1 s−1 (Ion/Ioff of 1 × 106) is, however, only obtained for the pure R/S mesomer, illustrating the inherent potential of stereochemical purity. These results on SCFETs are further substantiated by studies on organic thin‐film transistors (OTFTs) of pure and mixed thin films of the different stereoisomers.}, author = {He, Tao and Leowanawat, Pawaret and Burschka, Christian and Stepanenko, Vladimir and Stolte, Matthias and Würthner, Frank}, journal = {Advanced Materials}, keywords = {organic}, month = 11, pages = {1804032-1804039}, title = {Impact of 2-Ethylhexyl Stereoisomers on the Electrical Performance of Single-Crystal Field-Effect Transistors}, volume = 30, year = 2018 }

  %0 Journal Article %1 he2018impact %A He, Tao %A Leowanawat, Pawaret %A Burschka, Christian %A Stepanenko, Vladimir %A Stolte, Matthias %A Würthner, Frank %D 2018 %J Advanced Materials %P 1804032-1804039 %R 10.1002/adma.201804032 %T Impact of 2-Ethylhexyl Stereoisomers on the Electrical Performance of Single-Crystal Field-Effect Transistors %V 30 %X Many organic semiconductors (OSCs) inherit chiral alkyl chains, which ensure the desirable high solubility for solution‐processing but may also lead to disorder, inhomogeneous film‐formation, as well as interfacial defects due to the presence of mixtures of stereoisomers or diastereomers, which impair their peak performance. Here, single‐crystal field‐effect transistors (SCFETs) of a diketopyrrolopyrrole‐based organic semiconductor with chiral 2‐ethylhexyl substituents by sublimation in air and organic ribbon mask method are fabricated. Devices of the mesomer (R/S), both enantiomers (R/R, S/S), as well as mixtures of these three stereoisomers measured under ambient conditions exhibit all appreciable p‐channel charge carrier mobilities of > 0.1 cm2 V−1 s−1 despite different packing arrangement in the R/S, R/R (or S/S), and racemate crystal structures. These results suggest a surprising tolerance for isomeric impurities. The highest literature‐reported p‐channel mobility so far for a diketopyrrolopyrrole‐based OSC of 3.4 cm2 V−1 s−1 (Ion/Ioff of 1 × 106) is, however, only obtained for the pure R/S mesomer, illustrating the inherent potential of stereochemical purity. These results on SCFETs are further substantiated by studies on organic thin‐film transistors (OTFTs) of pure and mixed thin films of the different stereoisomers.
• Hydrogen-bonded perylene bisimide J-aggregate aqua material. Grande, Vincenzo; Soberats, Bartolome; Herbst, Stefanie; Stepanenko, Vladimir; Würthner, Frank. In Chemical Science, 9, pp. 6904 – 6911. 2018.
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  A new twelvefold methoxy-triethyleneglycol-jacketed tetraphenoxy-perylene bisimide (MEG-PBI) amphiphile was synthesized that self-assembles into two types of supramolecular aggregates in water: red-coloured aggregates of low order and with weak exciton coupling among the PBIs and blue-coloured strongly coupled J-aggregates consisting of a highly ordered hydrogen-bonded triple helix of PBIs. At room temperature this PBI is miscible with water at any proportions which enables the development of robust dye aggregates in solution, in hydrogel states and in lyotropic liquid crystalline states. In the presence of 60–95 wt% water, self-standing coloured hydrogels exhibit colour changes from red to blue accompanied by a fluorescence light-up in the far-red region upon heating in the range of 30–50 C. This phenomenon is triggered by an entropically driven temperature-induced hydrogen-bond-directed slipped stacking arrangement of the MEG-PBI chromophores within structurally well-de fined J-aggregates. This versatile aqua material is the first example of a stable PBI J-aggregate in water. We anticipate that this study will open a new avenue for the development of biocompatible functional materials based on self-assembled dyes and inspire the construction of other hydrogen-bonded supramolecular materials in the highly competitive solvent water.

  @article{grande2018hydrogenbonded, abstract = {A new twelvefold methoxy-triethyleneglycol-jacketed tetraphenoxy-perylene bisimide (MEG-PBI) amphiphile was synthesized that self-assembles into two types of supramolecular aggregates in water: red-coloured aggregates of low order and with weak exciton coupling among the PBIs and blue-coloured strongly coupled J-aggregates consisting of a highly ordered hydrogen-bonded triple helix of PBIs. At room temperature this PBI is miscible with water at any proportions which enables the development of robust dye aggregates in solution, in hydrogel states and in lyotropic liquid crystalline states. In the presence of 60–95 wt% water, self-standing coloured hydrogels exhibit colour changes from red to blue accompanied by a fluorescence light-up in the far-red region upon heating in the range of 30–50 C. This phenomenon is triggered by an entropically driven temperature-induced hydrogen-bond-directed slipped stacking arrangement of the MEG-PBI chromophores within structurally well-de fined J-aggregates. This versatile aqua material is the first example of a stable PBI J-aggregate in water. We anticipate that this study will open a new avenue for the development of biocompatible functional materials based on self-assembled dyes and inspire the construction of other hydrogen-bonded supramolecular materials in the highly competitive solvent water.}, author = {Grande, Vincenzo and Soberats, Bartolome and Herbst, Stefanie and Stepanenko, Vladimir and Würthner, Frank}, journal = {Chemical Science}, keywords = {organic}, month = {08}, pages = {6904 – 6911}, title = {Hydrogen-bonded perylene bisimide J-aggregate aqua material}, volume = 9, year = 2018 }

  %0 Journal Article %1 grande2018hydrogenbonded %A Grande, Vincenzo %A Soberats, Bartolome %A Herbst, Stefanie %A Stepanenko, Vladimir %A Würthner, Frank %D 2018 %J Chemical Science %P 6904 – 6911 %R 10.1039/c8sc02409j %T Hydrogen-bonded perylene bisimide J-aggregate aqua material %U https://pubs.rsc.org/en/content/articlelanding/2018/sc/c8sc02409j#!divAbstract %V 9 %X A new twelvefold methoxy-triethyleneglycol-jacketed tetraphenoxy-perylene bisimide (MEG-PBI) amphiphile was synthesized that self-assembles into two types of supramolecular aggregates in water: red-coloured aggregates of low order and with weak exciton coupling among the PBIs and blue-coloured strongly coupled J-aggregates consisting of a highly ordered hydrogen-bonded triple helix of PBIs. At room temperature this PBI is miscible with water at any proportions which enables the development of robust dye aggregates in solution, in hydrogel states and in lyotropic liquid crystalline states. In the presence of 60–95 wt% water, self-standing coloured hydrogels exhibit colour changes from red to blue accompanied by a fluorescence light-up in the far-red region upon heating in the range of 30–50 C. This phenomenon is triggered by an entropically driven temperature-induced hydrogen-bond-directed slipped stacking arrangement of the MEG-PBI chromophores within structurally well-de fined J-aggregates. This versatile aqua material is the first example of a stable PBI J-aggregate in water. We anticipate that this study will open a new avenue for the development of biocompatible functional materials based on self-assembled dyes and inspire the construction of other hydrogen-bonded supramolecular materials in the highly competitive solvent water.
• A General Synthetic Route to Polycyclic Aromatic Dicarboximides by Palladium-Catalyzed Annulation Reaction. Shoyama, Kazutaka; Mahl, Magnus; Seifert, Sabine; Würthner, Frank. In The Journal of Organic Chemistry, 83(10), pp. 5339–5346. 2018.
  • [ Abstract ]
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  Here we report a general method for the synthesis of polycyclic aromatic dicarboximides (PADIs) by palladium-catalyzed annulation of naphthalene dicarboximide to different types of aromatic substrates. Reaction conditions were optimized by systematic variation of ligand, solvent, and additive. It was shown that solvent has a decisive effect on the yield of the reaction products, and thus 1-chloronaphthalene as solvent afforded the highest yield. By applying the optimized reaction conditions, a broad series of planar carbo- and heterocycle containing PADIs were synthesized in up to 97% yield. Moreover, this approach could be applied to curved aromatic scaffold to achieve the respective bowl-shaped PADI. Two-fold annulation was accomplished by employing arene diboronic esters, affording polycyclic aromatic bis(dicarboximides). The optical and electrochemical properties of this broad series of PADIs were explored as well.

  @article{Shoyama_2018, abstract = {Here we report a general method for the synthesis of polycyclic aromatic dicarboximides (PADIs) by palladium-catalyzed annulation of naphthalene dicarboximide to different types of aromatic substrates. Reaction conditions were optimized by systematic variation of ligand, solvent, and additive. It was shown that solvent has a decisive effect on the yield of the reaction products, and thus 1-chloronaphthalene as solvent afforded the highest yield. By applying the optimized reaction conditions, a broad series of planar carbo- and heterocycle containing PADIs were synthesized in up to 97% yield. Moreover, this approach could be applied to curved aromatic scaffold to achieve the respective bowl-shaped PADI. Two-fold annulation was accomplished by employing arene diboronic esters, affording polycyclic aromatic bis(dicarboximides). The optical and electrochemical properties of this broad series of PADIs were explored as well.}, author = {Shoyama, Kazutaka and Mahl, Magnus and Seifert, Sabine and Würthner, Frank}, journal = {The Journal of Organic Chemistry}, keywords = {organic}, month = {03}, number = 10, pages = {5339–5346}, publisher = {American Chemical Society (ACS)}, title = {A General Synthetic Route to Polycyclic Aromatic Dicarboximides by Palladium-Catalyzed Annulation Reaction}, volume = 83, year = 2018 }

  %0 Journal Article %1 Shoyama_2018 %A Shoyama, Kazutaka %A Mahl, Magnus %A Seifert, Sabine %A Würthner, Frank %D 2018 %I American Chemical Society (ACS) %J The Journal of Organic Chemistry %N 10 %P 5339--5346 %R 10.1021/acs.joc.8b00301 %T A General Synthetic Route to Polycyclic Aromatic Dicarboximides by Palladium-Catalyzed Annulation Reaction %U https://doi.org/10.1021%2Facs.joc.8b00301 %V 83 %X Here we report a general method for the synthesis of polycyclic aromatic dicarboximides (PADIs) by palladium-catalyzed annulation of naphthalene dicarboximide to different types of aromatic substrates. Reaction conditions were optimized by systematic variation of ligand, solvent, and additive. It was shown that solvent has a decisive effect on the yield of the reaction products, and thus 1-chloronaphthalene as solvent afforded the highest yield. By applying the optimized reaction conditions, a broad series of planar carbo- and heterocycle containing PADIs were synthesized in up to 97% yield. Moreover, this approach could be applied to curved aromatic scaffold to achieve the respective bowl-shaped PADI. Two-fold annulation was accomplished by employing arene diboronic esters, affording polycyclic aromatic bis(dicarboximides). The optical and electrochemical properties of this broad series of PADIs were explored as well.
• Water-soluble naphthalene diimides: synthesis, optical properties, and colorimetric detection of biogenic amines. Weißenstein, Annike; Grande, Vincenzo; Saha-Möller, Chantu R; Würthner, Frank. In Org. Chem. Front., 5, pp. 2641–2651. 2018.
  • [ Abstract ]
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  A large number of water-soluble naphthalene diimides (NDIs) bearing an electron withdrawing chloro and electron-donating amino-substituents with varied electronic character at the core were synthesized by a two-step synthetic approach comprising imidization of 2,6-dichloronaphthalene dianhydride with L-glutamic acid or 2-dimethylaminoethylamine and subsequent nucleophilic substitution of a chlorine atom with primary amines. These new donor–acceptor NDI dyes show absorption and emission maxima beyond 500 nm and fluorescence quantum yields up to 39% in aqueous phosphate buffer solution at acidic and neutral pH values. Our studies revealed a significant effect of core amino-substituents on the optical properties of these NDIs. With increasing electron-withdrawing character of the residues of amino-substituents the absorption and emission maxima are more hypsochromically shifted and the fluorescence quantum yields are markedly increased with the highest value of 39% for NDIs containing a strongly electron withdrawing trifluroethyl group in the amino-substituent. Furthermore, the high reactivity of the core-dichlorinated NDI dye could be utilized for the optical detection of primary amines and biogenic diamines putrescine and cadaverine.

  @article{weissenstein2018watersoluble, abstract = {A large number of water-soluble naphthalene diimides (NDIs) bearing an electron withdrawing chloro and electron-donating amino-substituents with varied electronic character at the core were synthesized by a two-step synthetic approach comprising imidization of 2,6-dichloronaphthalene dianhydride with L-glutamic acid or 2-dimethylaminoethylamine and subsequent nucleophilic substitution of a chlorine atom with primary amines. These new donor–acceptor NDI dyes show absorption and emission maxima beyond 500 nm and fluorescence quantum yields up to 39% in aqueous phosphate buffer solution at acidic and neutral pH values. Our studies revealed a significant effect of core amino-substituents on the optical properties of these NDIs. With increasing electron-withdrawing character of the residues of amino-substituents the absorption and emission maxima are more hypsochromically shifted and the fluorescence quantum yields are markedly increased with the highest value of 39% for NDIs containing a strongly electron withdrawing trifluroethyl group in the amino-substituent. Furthermore, the high reactivity of the core-dichlorinated NDI dye could be utilized for the optical detection of primary amines and biogenic diamines putrescine and cadaverine.}, author = {Weißenstein, Annike and Grande, Vincenzo and Saha-Möller, Chantu R and Würthner, Frank}, journal = {Org. Chem. Front.}, keywords = {organic}, month = {09}, pages = {2641–2651}, title = {Water-soluble naphthalene diimides: synthesis, optical properties, and colorimetric detection of biogenic amines}, volume = 5, year = 2018 }

  %0 Journal Article %1 weissenstein2018watersoluble %A Weißenstein, Annike %A Grande, Vincenzo %A Saha-Möller, Chantu R %A Würthner, Frank %D 2018 %J Org. Chem. Front. %P 2641–2651 %R 10.1039/c8qo00611c %T Water-soluble naphthalene diimides: synthesis, optical properties, and colorimetric detection of biogenic amines %V 5 %X A large number of water-soluble naphthalene diimides (NDIs) bearing an electron withdrawing chloro and electron-donating amino-substituents with varied electronic character at the core were synthesized by a two-step synthetic approach comprising imidization of 2,6-dichloronaphthalene dianhydride with L-glutamic acid or 2-dimethylaminoethylamine and subsequent nucleophilic substitution of a chlorine atom with primary amines. These new donor–acceptor NDI dyes show absorption and emission maxima beyond 500 nm and fluorescence quantum yields up to 39% in aqueous phosphate buffer solution at acidic and neutral pH values. Our studies revealed a significant effect of core amino-substituents on the optical properties of these NDIs. With increasing electron-withdrawing character of the residues of amino-substituents the absorption and emission maxima are more hypsochromically shifted and the fluorescence quantum yields are markedly increased with the highest value of 39% for NDIs containing a strongly electron withdrawing trifluroethyl group in the amino-substituent. Furthermore, the high reactivity of the core-dichlorinated NDI dye could be utilized for the optical detection of primary amines and biogenic diamines putrescine and cadaverine.
• Naphthalene and perylene diimides – better alternatives to fullerenes for organic electronics?. Nowak-Król, A.; Shoyama, K.; Stolte, M.; Würthner, F. In Chemical Communication, 54, pp. 13763–13772. 2018.
  • [ Abstract ]
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  The LUMO levels of rylene diimides are highly comparable to those of fullerenes but this class of molecules offers tunability of both HOMO and LUMO levels and the related band gap by either simple substitution at the aromatic core or annulation to give expanded π-scaffolds. In this article we highlight the most outstanding achievements during the last decade in terms of charge carrier mobility for organic thin-film and single crystal field-effect transistors as well as photovoltaic performance for both small molecule and polymeric compounds.

  @article{nowakkrol2018101039c8cc07640e, abstract = {The LUMO levels of rylene diimides are highly comparable to those of fullerenes but this class of molecules offers tunability of both HOMO and LUMO levels and the related band gap by either simple substitution at the aromatic core or annulation to give expanded π-scaffolds. In this article we highlight the most outstanding achievements during the last decade in terms of charge carrier mobility for organic thin-film and single crystal field-effect transistors as well as photovoltaic performance for both small molecule and polymeric compounds.}, author = {Nowak-Król, A. and Shoyama, K. and Stolte, M. and Würthner, F.}, journal = {Chemical Communication}, keywords = {organic}, month = 11, pages = {13763-13772}, title = {Naphthalene and perylene diimides – better alternatives to fullerenes for organic electronics?}, volume = 54, year = 2018 }

  %0 Journal Article %1 nowakkrol2018101039c8cc07640e %A Nowak-Król, A. %A Shoyama, K. %A Stolte, M. %A Würthner, F. %D 2018 %J Chemical Communication %P 13763-13772 %R 10.1039/C8CC07640E %T Naphthalene and perylene diimides – better alternatives to fullerenes for organic electronics? %U https://pubs.rsc.org/en/content/articlelanding/2018/cc/c8cc07640e#!divAbstract %V 54 %X The LUMO levels of rylene diimides are highly comparable to those of fullerenes but this class of molecules offers tunability of both HOMO and LUMO levels and the related band gap by either simple substitution at the aromatic core or annulation to give expanded π-scaffolds. In this article we highlight the most outstanding achievements during the last decade in terms of charge carrier mobility for organic thin-film and single crystal field-effect transistors as well as photovoltaic performance for both small molecule and polymeric compounds.
• Coupled Cooperative Supramolecular Polymerization: A New Model Applied to the Competing Aggregation Pathways of an Amphiphilic aza-BODIPY Dye into Spherical and Rod-Like Aggregates. Liu, Yong; Zhang, Yongjie; Fennel, Dr. Franziska; Wagner, Wolfgang; Würthner, Prof. Frank; Chen, Yuanfang; Chen, Prof. Zhijian. In Chem. Eur. J., 24(61), pp. 16388–16394. 2018.
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  Based on our studies on biphasic self‐assembly behavior of an amphiphilic BF2‐azadipyrromethene (aza‐BODIPY) dye 1, a new analytical model to quantitatively describe the thermodynamic properties of the aggregation involving two competing supramolecular polymerization processes is proposed. In this model, the formation of the metastable as well as the thermodynamically stable aggregates was considered to follow a nucleated polymerization mechanism. The numerical calculation based on the new model gives insight into the formation of different species in such complicate aggregate systems. Moreover, the aggregation of the biphasic self‐assembly processes for dye 1 was investigated by concentration‐dependent UV/Vis spectroscopy. The experimental data were analyzed by using the new model to evaluate the thermodynamic parameters including aggregation constants, the size of nuclei, and the cooperativity the two types of aggregates.

  @article{noauthororeditor, abstract = {Based on our studies on biphasic self‐assembly behavior of an amphiphilic BF2‐azadipyrromethene (aza‐BODIPY) dye 1, a new analytical model to quantitatively describe the thermodynamic properties of the aggregation involving two competing supramolecular polymerization processes is proposed. In this model, the formation of the metastable as well as the thermodynamically stable aggregates was considered to follow a nucleated polymerization mechanism. The numerical calculation based on the new model gives insight into the formation of different species in such complicate aggregate systems. Moreover, the aggregation of the biphasic self‐assembly processes for dye 1 was investigated by concentration‐dependent UV/Vis spectroscopy. The experimental data were analyzed by using the new model to evaluate the thermodynamic parameters including aggregation constants, the size of nuclei, and the cooperativity the two types of aggregates.}, author = {Liu, Yong and Zhang, Yongjie and Fennel, Dr. Franziska and Wagner, Wolfgang and Würthner, Prof. Frank and Chen, Yuanfang and Chen, Prof. Zhijian}, journal = {Chem. Eur. J.}, keywords = {organic}, month = 11, number = 61, pages = {16388-16394}, title = {Coupled Cooperative Supramolecular Polymerization: A New Model Applied to the Competing Aggregation Pathways of an Amphiphilic aza-BODIPY Dye into Spherical and Rod-Like Aggregates}, volume = 24, year = 2018 }

  %0 Journal Article %1 noauthororeditor %A Liu, Yong %A Zhang, Yongjie %A Fennel, Dr. Franziska %A Wagner, Wolfgang %A Würthner, Prof. Frank %A Chen, Yuanfang %A Chen, Prof. Zhijian %D 2018 %J Chem. Eur. J. %N 61 %P 16388-16394 %R 10.1002/chem.201803336 %T Coupled Cooperative Supramolecular Polymerization: A New Model Applied to the Competing Aggregation Pathways of an Amphiphilic aza-BODIPY Dye into Spherical and Rod-Like Aggregates %V 24 %X Based on our studies on biphasic self‐assembly behavior of an amphiphilic BF2‐azadipyrromethene (aza‐BODIPY) dye 1, a new analytical model to quantitatively describe the thermodynamic properties of the aggregation involving two competing supramolecular polymerization processes is proposed. In this model, the formation of the metastable as well as the thermodynamically stable aggregates was considered to follow a nucleated polymerization mechanism. The numerical calculation based on the new model gives insight into the formation of different species in such complicate aggregate systems. Moreover, the aggregation of the biphasic self‐assembly processes for dye 1 was investigated by concentration‐dependent UV/Vis spectroscopy. The experimental data were analyzed by using the new model to evaluate the thermodynamic parameters including aggregation constants, the size of nuclei, and the cooperativity the two types of aggregates.
• Self-assembly of multi-stranded perylene dye J-aggregates in columnar liquid-crystalline phases. Herbst, Stefanie; Soberats, Bartolome; Leowanawat, Pawaret; Stolte, Matthias; Lehmann, Matthias; Würthner, Frank. In Nature Communications, 9(1), pp. 2646–2654. 2018.
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  Many discoid dyes self-assemble into columnar liquid-crystalline (LC) phases with packing arrangements that are undesired for photonic applications due to H-type exciton coupling. Here, we report a series of crystalline and LC perylene bisimides (PBIs) self-assembling into single or multi-stranded (two, three, and four strands) aggregates with predominant J-type exciton coupling. These differences in the supramolecular packing and optical properties are achieved by molecular design variations of tetra-bay phenoxy-dendronized PBIs with two N–H groups at the imide positions. The self-assembly is driven by hydrogen bonding, slipped π–π stacking, nanosegregation, and steric requirements of the peripheral building blocks. We could determine the impact of the packing motifs on the spectroscopic properties and demonstrate different J- and H-type coupling contributions between the chromophores. Our findings on structure–property relationships and strong J-couplings in bulk LC materials open a new avenue in the molecular engineering of PBI J-aggregates with prospective applications in photonics.

  @article{herbst2018selfassembly, abstract = {Many discoid dyes self-assemble into columnar liquid-crystalline (LC) phases with packing arrangements that are undesired for photonic applications due to H-type exciton coupling. Here, we report a series of crystalline and LC perylene bisimides (PBIs) self-assembling into single or multi-stranded (two, three, and four strands) aggregates with predominant J-type exciton coupling. These differences in the supramolecular packing and optical properties are achieved by molecular design variations of tetra-bay phenoxy-dendronized PBIs with two N–H groups at the imide positions. The self-assembly is driven by hydrogen bonding, slipped π–π stacking, nanosegregation, and steric requirements of the peripheral building blocks. We could determine the impact of the packing motifs on the spectroscopic properties and demonstrate different J- and H-type coupling contributions between the chromophores. Our findings on structure–property relationships and strong J-couplings in bulk LC materials open a new avenue in the molecular engineering of PBI J-aggregates with prospective applications in photonics.}, author = {Herbst, Stefanie and Soberats, Bartolome and Leowanawat, Pawaret and Stolte, Matthias and Lehmann, Matthias and Würthner, Frank}, journal = {Nature Communications}, keywords = {organic}, month = {07}, number = 1, pages = {2646–2654}, title = {Self-assembly of multi-stranded perylene dye J-aggregates in columnar liquid-crystalline phases}, volume = 9, year = 2018 }

  %0 Journal Article %1 herbst2018selfassembly %A Herbst, Stefanie %A Soberats, Bartolome %A Leowanawat, Pawaret %A Stolte, Matthias %A Lehmann, Matthias %A Würthner, Frank %D 2018 %J Nature Communications %N 1 %P 2646--2654 %R 10.1038/s41467-018-05018-6 %T Self-assembly of multi-stranded perylene dye J-aggregates in columnar liquid-crystalline phases %U https://doi.org/10.1038/s41467-018-05018-6 %V 9 %X Many discoid dyes self-assemble into columnar liquid-crystalline (LC) phases with packing arrangements that are undesired for photonic applications due to H-type exciton coupling. Here, we report a series of crystalline and LC perylene bisimides (PBIs) self-assembling into single or multi-stranded (two, three, and four strands) aggregates with predominant J-type exciton coupling. These differences in the supramolecular packing and optical properties are achieved by molecular design variations of tetra-bay phenoxy-dendronized PBIs with two N–H groups at the imide positions. The self-assembly is driven by hydrogen bonding, slipped π–π stacking, nanosegregation, and steric requirements of the peripheral building blocks. We could determine the impact of the packing motifs on the spectroscopic properties and demonstrate different J- and H-type coupling contributions between the chromophores. Our findings on structure–property relationships and strong J-couplings in bulk LC materials open a new avenue in the molecular engineering of PBI J-aggregates with prospective applications in photonics.
• All-in-one visible-light-driven water splitting by combining nanoparticulate and molecular co-catalysts on CdS nanorods. Wolff, Christian M.; Frischmann, Peter D.; Schulze, Marcus; Bohn, Bernhard J.; Wein, Robin; Livadas, Panajotis; Carlson, Michael T.; Jäckel, Frank; Feldmann, Jochen; Würthner, Frank; Stolarczyk, Jacek K. In Nature Energy, 3(10), pp. 862–869. 2018.
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  Full water splitting into hydrogen and oxygen on semiconductor nanocrystals is a challenging task; overpotentials must be overcome for both half-reactions and different catalytic sites are needed to facilitate them. Additionally, efficient charge separation and prevention of back reactions are necessary. Here, we report simultaneous H2 and O2 evolution by CdS nanorods decorated with nanoparticulate reduction and molecular oxidation co-catalysts. The process proceeds entirely without sacrificial agents and relies on the nanorod morphology of CdS to spatially separate the reduction and oxidation sites. Hydrogen is generated on Pt nanoparticles grown at the nanorod tips, while Ru(tpy)(bpy)Cl2-based oxidation catalysts are anchored through dithiocarbamate bonds onto the sides of the nanorod. O2 generation from water was verified by 18O isotope labelling experiments, and time-resolved spectroscopic results confirmed efficient charge separation and ultrafast electron and hole transfer to the reaction sites. The system demonstrates that combining nanoparticulate and molecular catalysts on anisotropic nanocrystals provides an effective pathway for visible-light-driven photocatalytic water splitting.

  @article{Wolff_2018, abstract = {Full water splitting into hydrogen and oxygen on semiconductor nanocrystals is a challenging task; overpotentials must be overcome for both half-reactions and different catalytic sites are needed to facilitate them. Additionally, efficient charge separation and prevention of back reactions are necessary. Here, we report simultaneous H2 and O2 evolution by CdS nanorods decorated with nanoparticulate reduction and molecular oxidation co-catalysts. The process proceeds entirely without sacrificial agents and relies on the nanorod morphology of CdS to spatially separate the reduction and oxidation sites. Hydrogen is generated on Pt nanoparticles grown at the nanorod tips, while Ru(tpy)(bpy)Cl2-based oxidation catalysts are anchored through dithiocarbamate bonds onto the sides of the nanorod. O2 generation from water was verified by 18O isotope labelling experiments, and time-resolved spectroscopic results confirmed efficient charge separation and ultrafast electron and hole transfer to the reaction sites. The system demonstrates that combining nanoparticulate and molecular catalysts on anisotropic nanocrystals provides an effective pathway for visible-light-driven photocatalytic water splitting.}, author = {Wolff, Christian M. and Frischmann, Peter D. and Schulze, Marcus and Bohn, Bernhard J. and Wein, Robin and Livadas, Panajotis and Carlson, Michael T. and Jäckel, Frank and Feldmann, Jochen and Würthner, Frank and Stolarczyk, Jacek K.}, journal = {Nature Energy}, keywords = {myown}, month = {09}, number = 10, pages = {862–869}, publisher = {Springer Science and Business Media {LLC}}, title = {All-in-one visible-light-driven water splitting by combining nanoparticulate and molecular co-catalysts on CdS nanorods}, volume = 3, year = 2018 }

  %0 Journal Article %1 Wolff_2018 %A Wolff, Christian M. %A Frischmann, Peter D. %A Schulze, Marcus %A Bohn, Bernhard J. %A Wein, Robin %A Livadas, Panajotis %A Carlson, Michael T. %A Jäckel, Frank %A Feldmann, Jochen %A Würthner, Frank %A Stolarczyk, Jacek K. %D 2018 %I Springer Science and Business Media LLC %J Nature Energy %N 10 %P 862--869 %R 10.1038/s41560-018-0229-6 %T All-in-one visible-light-driven water splitting by combining nanoparticulate and molecular co-catalysts on CdS nanorods %U https://doi.org/10.1038%2Fs41560-018-0229-6 %V 3 %X Full water splitting into hydrogen and oxygen on semiconductor nanocrystals is a challenging task; overpotentials must be overcome for both half-reactions and different catalytic sites are needed to facilitate them. Additionally, efficient charge separation and prevention of back reactions are necessary. Here, we report simultaneous H2 and O2 evolution by CdS nanorods decorated with nanoparticulate reduction and molecular oxidation co-catalysts. The process proceeds entirely without sacrificial agents and relies on the nanorod morphology of CdS to spatially separate the reduction and oxidation sites. Hydrogen is generated on Pt nanoparticles grown at the nanorod tips, while Ru(tpy)(bpy)Cl2-based oxidation catalysts are anchored through dithiocarbamate bonds onto the sides of the nanorod. O2 generation from water was verified by 18O isotope labelling experiments, and time-resolved spectroscopic results confirmed efficient charge separation and ultrafast electron and hole transfer to the reaction sites. The system demonstrates that combining nanoparticulate and molecular catalysts on anisotropic nanocrystals provides an effective pathway for visible-light-driven photocatalytic water splitting.
• Discrete π-Stacks of Perylene Bisimide Dyes within Folda-Dimers: Insight into Long- and Short-Range Exciton Coupling. Kaufmann, Christina; Bialas, David; Stolte, Matthias; Würthner, Frank. In J. Am. Chem. Soc., 140(31), pp. 9986–9995. 2018.
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  Four well-defined π-stacks of perylene bisimide (PBI) dyes were obtained in solution by covalent linkage of two chromophores with spacer units of different length and sterical demand. Structural elucidation of the folda-dimers by in-depth nuclear magnetic resonance studies and geometry optimization at the level of density functional theory suggest different, but highly defined molecular arrangements of the two chromophores in the folded state enforced by the various spacer moieties. Remarkably, the dye stacks exhibit considerably different optical properties as investigated by UV/vis absorption and fluorescence spectroscopy, despite only slightly different chromophore arrangements. The distinct absorption properties can be rationalized by an interplay of long- and short-range exciton coupling resulting in optical signatures ranging from conventional H-type to monomer like absorption features with low and appreciably high fluorescence quantum yields, respectively. To the best of our knowledge, we present the first experimental proof of a PBI-based “null-aggregate”, in which long- and short-range exciton coupling fully compensate each other, giving rise to monomer-like absorption features for a stack of two PBI chromophores. Hence, our insights pinpoint the importance of charge-transfer mediated short-range coupling that can significantly influence the optical properties of PBI π-stacks.

  @article{Kaufmann_2018, abstract = {Four well-defined π-stacks of perylene bisimide (PBI) dyes were obtained in solution by covalent linkage of two chromophores with spacer units of different length and sterical demand. Structural elucidation of the folda-dimers by in-depth nuclear magnetic resonance studies and geometry optimization at the level of density functional theory suggest different, but highly defined molecular arrangements of the two chromophores in the folded state enforced by the various spacer moieties. Remarkably, the dye stacks exhibit considerably different optical properties as investigated by UV/vis absorption and fluorescence spectroscopy, despite only slightly different chromophore arrangements. The distinct absorption properties can be rationalized by an interplay of long- and short-range exciton coupling resulting in optical signatures ranging from conventional H-type to monomer like absorption features with low and appreciably high fluorescence quantum yields, respectively. To the best of our knowledge, we present the first experimental proof of a PBI-based “null-aggregate”, in which long- and short-range exciton coupling fully compensate each other, giving rise to monomer-like absorption features for a stack of two PBI chromophores. Hence, our insights pinpoint the importance of charge-transfer mediated short-range coupling that can significantly influence the optical properties of PBI π-stacks.}, author = {Kaufmann, Christina and Bialas, David and Stolte, Matthias and Würthner, Frank}, journal = {J. Am. Chem. Soc.}, keywords = {irganic}, month = {07}, number = 31, pages = {9986–9995}, publisher = {American Chemical Society ({ACS})}, title = {Discrete π-Stacks of Perylene Bisimide Dyes within Folda-Dimers: Insight into Long- and Short-Range Exciton Coupling}, volume = 140, year = 2018 }

  %0 Journal Article %1 Kaufmann_2018 %A Kaufmann, Christina %A Bialas, David %A Stolte, Matthias %A Würthner, Frank %D 2018 %I American Chemical Society (ACS) %J J. Am. Chem. Soc. %N 31 %P 9986--9995 %R 10.1021/jacs.8b05490 %T Discrete π-Stacks of Perylene Bisimide Dyes within Folda-Dimers: Insight into Long- and Short-Range Exciton Coupling %U https://doi.org/10.1021%2Fjacs.8b05490 %V 140 %X Four well-defined π-stacks of perylene bisimide (PBI) dyes were obtained in solution by covalent linkage of two chromophores with spacer units of different length and sterical demand. Structural elucidation of the folda-dimers by in-depth nuclear magnetic resonance studies and geometry optimization at the level of density functional theory suggest different, but highly defined molecular arrangements of the two chromophores in the folded state enforced by the various spacer moieties. Remarkably, the dye stacks exhibit considerably different optical properties as investigated by UV/vis absorption and fluorescence spectroscopy, despite only slightly different chromophore arrangements. The distinct absorption properties can be rationalized by an interplay of long- and short-range exciton coupling resulting in optical signatures ranging from conventional H-type to monomer like absorption features with low and appreciably high fluorescence quantum yields, respectively. To the best of our knowledge, we present the first experimental proof of a PBI-based “null-aggregate”, in which long- and short-range exciton coupling fully compensate each other, giving rise to monomer-like absorption features for a stack of two PBI chromophores. Hence, our insights pinpoint the importance of charge-transfer mediated short-range coupling that can significantly influence the optical properties of PBI π-stacks.
• Photoinduced Dynamics of Bis-dipyrrinato-palladium(II) and Porphodimethenato-palladium(II) Complexes: Governing Near Infrared Phosphorescence by Structural Restriction. Riese, Stefan; Holzapfel, Marco; Schmiedel, Alexander; Gert, Ingo; Schmidt, David; Würthner, Frank; Lambert, Christoph. In Inorganic Chemistry, 57(20), pp. 12480–12488. 2018.
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  Although superficially similar, the bis-dipyrrinato-palladium(II) complex 1 and the bridged porphodimethenato-palladium(II) complex 2 possess dramatically different structures in the ground state (proved by X-ray structure analysis) and in the singlet and triplet excited states (calculated by density functional theory methods). While complex 2 is rather rigid, complex 1 undergoes a major structural reorganization in the excited state to yield a disphenoidal (seesaw) triplet state. The dynamics of the excited states were probed by transient absorption spectroscopy with femtosecond and nanosecond time resolution and with fluorescence upconversion and yield intersystem crossing rate constants of ca. (13–16 ps)−1. The observation of significant near infrared phosphorescence in complex 2 but the absence of any emission in complex 1 in fluid solution could be rationalized by the structural reorganization of 1 which results in a nonemissive triplet metal centered state.

  @article{Riese_2018, abstract = {Although superficially similar, the bis-dipyrrinato-palladium(II) complex 1 and the bridged porphodimethenato-palladium(II) complex 2 possess dramatically different structures in the ground state (proved by X-ray structure analysis) and in the singlet and triplet excited states (calculated by density functional theory methods). While complex 2 is rather rigid, complex 1 undergoes a major structural reorganization in the excited state to yield a disphenoidal (seesaw) triplet state. The dynamics of the excited states were probed by transient absorption spectroscopy with femtosecond and nanosecond time resolution and with fluorescence upconversion and yield intersystem crossing rate constants of ca. (13–16 ps)−1. The observation of significant near infrared phosphorescence in complex 2 but the absence of any emission in complex 1 in fluid solution could be rationalized by the structural reorganization of 1 which results in a nonemissive triplet metal centered state.}, author = {Riese, Stefan and Holzapfel, Marco and Schmiedel, Alexander and Gert, Ingo and Schmidt, David and Würthner, Frank and Lambert, Christoph}, journal = {Inorganic Chemistry}, keywords = {organic}, month = {06}, number = 20, pages = {12480–12488}, publisher = {American Chemical Society (ACS)}, title = {Photoinduced Dynamics of Bis-dipyrrinato-palladium(II) and Porphodimethenato-palladium(II) Complexes: Governing Near Infrared Phosphorescence by Structural Restriction}, volume = 57, year = 2018 }

  %0 Journal Article %1 Riese_2018 %A Riese, Stefan %A Holzapfel, Marco %A Schmiedel, Alexander %A Gert, Ingo %A Schmidt, David %A Würthner, Frank %A Lambert, Christoph %D 2018 %I American Chemical Society (ACS) %J Inorganic Chemistry %N 20 %P 12480--12488 %R 10.1021/acs.inorgchem.8b00974 %T Photoinduced Dynamics of Bis-dipyrrinato-palladium(II) and Porphodimethenato-palladium(II) Complexes: Governing Near Infrared Phosphorescence by Structural Restriction %U https://doi.org/10.1021%2Facs.inorgchem.8b00974 %V 57 %X Although superficially similar, the bis-dipyrrinato-palladium(II) complex 1 and the bridged porphodimethenato-palladium(II) complex 2 possess dramatically different structures in the ground state (proved by X-ray structure analysis) and in the singlet and triplet excited states (calculated by density functional theory methods). While complex 2 is rather rigid, complex 1 undergoes a major structural reorganization in the excited state to yield a disphenoidal (seesaw) triplet state. The dynamics of the excited states were probed by transient absorption spectroscopy with femtosecond and nanosecond time resolution and with fluorescence upconversion and yield intersystem crossing rate constants of ca. (13–16 ps)−1. The observation of significant near infrared phosphorescence in complex 2 but the absence of any emission in complex 1 in fluid solution could be rationalized by the structural reorganization of 1 which results in a nonemissive triplet metal centered state.
• Stable Organic (Bi)Radicals by Delocalization of Spin Density into the Electron‐Poor Chromophore Core of Isoindigo. Rausch, Rodger; Schmidt, David; Bialas, David; Krummenacher, Ivo; Braunschweig, Holger; Würthner, Frank. In Chemistry - A European Journal, 24(14), pp. 3420–3424. 2018.
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  The first isoindigo (bi)radicals were obtained by proton coupled oxidation of their 4‐hydroxyaryl substituted precursors. Optical and magnetic spectroscopic studies revealed a singlet open‐shell biradicaloid electronic ground state for the bisphenoxyl‐isoindigo (<s2>=1.20) with a small singlet–triplet energy gap of 0.065 eV and a large biradical character of y=0.79 that was corroborated by temperature‐dependent EPR spectroscopy and quantum chemical calculations. The concept of kinetic blocking of the radical centers and delocalization of spin density into the electron‐withdrawing chromophore core of isoindigo offers an entry into a new class of exceptionally stable open‐shell functional materials based on organic colorants.

  @article{rausch2018stable, abstract = {The first isoindigo (bi)radicals were obtained by proton coupled oxidation of their 4‐hydroxyaryl substituted precursors. Optical and magnetic spectroscopic studies revealed a singlet open‐shell biradicaloid electronic ground state for the bisphenoxyl‐isoindigo (<s2>=1.20) with a small singlet–triplet energy gap of 0.065 eV and a large biradical character of y=0.79 that was corroborated by temperature‐dependent EPR spectroscopy and quantum chemical calculations. The concept of kinetic blocking of the radical centers and delocalization of spin density into the electron‐withdrawing chromophore core of isoindigo offers an entry into a new class of exceptionally stable open‐shell functional materials based on organic colorants.}, author = {Rausch, Rodger and Schmidt, David and Bialas, David and Krummenacher, Ivo and Braunschweig, Holger and Würthner, Frank}, journal = {Chemistry - A European Journal}, keywords = {organic}, month = {03}, number = 14, pages = {3420-3424}, title = {Stable Organic (Bi)Radicals by Delocalization of Spin Density into the Electron‐Poor Chromophore Core of Isoindigo}, volume = 24, year = 2018 }

  %0 Journal Article %1 rausch2018stable %A Rausch, Rodger %A Schmidt, David %A Bialas, David %A Krummenacher, Ivo %A Braunschweig, Holger %A Würthner, Frank %D 2018 %J Chemistry - A European Journal %N 14 %P 3420-3424 %R 10.1002/chem.201706002 %T Stable Organic (Bi)Radicals by Delocalization of Spin Density into the Electron‐Poor Chromophore Core of Isoindigo %V 24 %X The first isoindigo (bi)radicals were obtained by proton coupled oxidation of their 4‐hydroxyaryl substituted precursors. Optical and magnetic spectroscopic studies revealed a singlet open‐shell biradicaloid electronic ground state for the bisphenoxyl‐isoindigo (<s2>=1.20) with a small singlet–triplet energy gap of 0.065 eV and a large biradical character of y=0.79 that was corroborated by temperature‐dependent EPR spectroscopy and quantum chemical calculations. The concept of kinetic blocking of the radical centers and delocalization of spin density into the electron‐withdrawing chromophore core of isoindigo offers an entry into a new class of exceptionally stable open‐shell functional materials based on organic colorants.
• Ultrafast Exciton Delocalization, Localization, and Excimer Formation Dynamics in a Highly Defined Perylene Bisimide Quadruple π-Stack. Kaufmann, Christina; Kim, Woojae; Nowak-Król, Agnieszka; Hong, Yongseok; Kim, Dongho; Würthner, Frank. In J. Am. Chem. Soc., 140(12), pp. 4253–4258. 2018.
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  An adequately designed, bay-tethered perylene bisimide (PBI) dimer Bis-PBI was synthesized by Pd/Cu-catalyzed Glaser-type oxidative homocoupling of the respective PBI building block. This newly synthesized PBI dimer self-assembles exclusively and with high binding constants of up to 106 M–1 into a discrete π-stack of four chromophores. Steady-state absorption and emission spectra show the signatures of H-type excitonic coupling among the dye units. Broadband fluorescence upconversion spectroscopy (FLUPS) reveals an ultrafast dynamics in the optically excited state. An initially coherent Frenkel exciton state that is delocalized over the whole quadruple stack rapidly (τ = ∼200 fs) loses its coherence and relaxes into an excimer state. Comparison with Frenkel exciton dynamics in PBI dimeric and oligomeric H-aggregates demonstrates that in the quadruple stack coherent exciton propagation is absent due to its short length of aggregates, thereby it has only one relaxation pathway to the excimer state. Furthermore, the absence of pump-power dependence in transient absorption experiments suggests that multiexciton cannot be generated in the quadruple stack, which is in line with time-resolved fluorescence measurements.

  @article{Kaufmann_2018, abstract = {An adequately designed, bay-tethered perylene bisimide (PBI) dimer Bis-PBI was synthesized by Pd/Cu-catalyzed Glaser-type oxidative homocoupling of the respective PBI building block. This newly synthesized PBI dimer self-assembles exclusively and with high binding constants of up to 106 M–1 into a discrete π-stack of four chromophores. Steady-state absorption and emission spectra show the signatures of H-type excitonic coupling among the dye units. Broadband fluorescence upconversion spectroscopy (FLUPS) reveals an ultrafast dynamics in the optically excited state. An initially coherent Frenkel exciton state that is delocalized over the whole quadruple stack rapidly (τ = ∼200 fs) loses its coherence and relaxes into an excimer state. Comparison with Frenkel exciton dynamics in PBI dimeric and oligomeric H-aggregates demonstrates that in the quadruple stack coherent exciton propagation is absent due to its short length of aggregates, thereby it has only one relaxation pathway to the excimer state. Furthermore, the absence of pump-power dependence in transient absorption experiments suggests that multiexciton cannot be generated in the quadruple stack, which is in line with time-resolved fluorescence measurements.}, author = {Kaufmann, Christina and Kim, Woojae and Nowak-Król, Agnieszka and Hong, Yongseok and Kim, Dongho and Würthner, Frank}, journal = {J. Am. Chem. Soc.}, keywords = {organic}, month = {03}, number = 12, pages = {4253–4258}, publisher = {American Chemical Society (ACS)}, title = {Ultrafast Exciton Delocalization, Localization, and Excimer Formation Dynamics in a Highly Defined Perylene Bisimide Quadruple π-Stack}, volume = 140, year = 2018 }

  %0 Journal Article %1 Kaufmann_2018 %A Kaufmann, Christina %A Kim, Woojae %A Nowak-Król, Agnieszka %A Hong, Yongseok %A Kim, Dongho %A Würthner, Frank %D 2018 %I American Chemical Society (ACS) %J J. Am. Chem. Soc. %N 12 %P 4253--4258 %R 10.1021/jacs.7b11571 %T Ultrafast Exciton Delocalization, Localization, and Excimer Formation Dynamics in a Highly Defined Perylene Bisimide Quadruple π-Stack %U https://doi.org/10.1021%2Fjacs.7b11571 %V 140 %X An adequately designed, bay-tethered perylene bisimide (PBI) dimer Bis-PBI was synthesized by Pd/Cu-catalyzed Glaser-type oxidative homocoupling of the respective PBI building block. This newly synthesized PBI dimer self-assembles exclusively and with high binding constants of up to 106 M–1 into a discrete π-stack of four chromophores. Steady-state absorption and emission spectra show the signatures of H-type excitonic coupling among the dye units. Broadband fluorescence upconversion spectroscopy (FLUPS) reveals an ultrafast dynamics in the optically excited state. An initially coherent Frenkel exciton state that is delocalized over the whole quadruple stack rapidly (τ = ∼200 fs) loses its coherence and relaxes into an excimer state. Comparison with Frenkel exciton dynamics in PBI dimeric and oligomeric H-aggregates demonstrates that in the quadruple stack coherent exciton propagation is absent due to its short length of aggregates, thereby it has only one relaxation pathway to the excimer state. Furthermore, the absence of pump-power dependence in transient absorption experiments suggests that multiexciton cannot be generated in the quadruple stack, which is in line with time-resolved fluorescence measurements.
• Pathway complexity in the self-assembly of a zinc chlorin model system of natural bacteriochlorophyll J-aggregates. Ogi, Soichiro; Grzeszkiewicz, Charlotte; Würthner, Frank. In Chem. Sci., 9(10), pp. 2768–2773. 2018.
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  Whilst bacteriochlorophyll c, d, and e dyes self-assemble into the most efficient light harvesting J-aggregate systems found in nature, their supramolecular packing arrangements are still a matter of debate and a significant number of models have been suggested for their local and long-range ordering. Here we reveal for a synthetic model system based on a zinc chlorin (ZnChl) dye an intriguing interplay of two competing aggregation pathways by kinetic and thermodynamic studies in MeOH/water solvent mixtures: the formation of kinetically controlled off-pathway nanoparticles consisting of excitonically coupled J-dimers versus the formation of thermodynamically more stable one-dimensional helical fibers consisting of J-coupled extended aggregates. The higher order of the latter is evidenced by atomic force microscopy and a more narrow absorption spectrum of the J-aggregates. Based on a recently developed thermodynamic model that combines the cooperative K2-K growth model with a competing dimerization model, an energy landscape could be derived that describes the pathway complexity of this biomimetic system. Our studies reveal that the kinetic stability of the off-pathway nanoparticles increases with increasing concentration of ZnChl or water content in a MeOH/water solvent mixture. For a water content >90% deeply trapped off-pathway nanoparticle products are formed that do not transform anymore to the more ordered thermodynamic product within reasonable time scales. Based on these observations, we hypothesize that out-of-equilibrium aggregate structures of natural BChl dyes may also exist in the natural chlorosomes of green bacteria.

  @article{C7SC03725B, abstract = {Whilst bacteriochlorophyll c{,} d{,} and e dyes self-assemble into the most efficient light harvesting J-aggregate systems found in nature{,} their supramolecular packing arrangements are still a matter of debate and a significant number of models have been suggested for their local and long-range ordering. Here we reveal for a synthetic model system based on a zinc chlorin (ZnChl) dye an intriguing interplay of two competing aggregation pathways by kinetic and thermodynamic studies in MeOH/water solvent mixtures: the formation of kinetically controlled off-pathway nanoparticles consisting of excitonically coupled J-dimers versus the formation of thermodynamically more stable one-dimensional helical fibers consisting of J-coupled extended aggregates. The higher order of the latter is evidenced by atomic force microscopy and a more narrow absorption spectrum of the J-aggregates. Based on a recently developed thermodynamic model that combines the cooperative K2-K growth model with a competing dimerization model{,} an energy landscape could be derived that describes the pathway complexity of this biomimetic system. Our studies reveal that the kinetic stability of the off-pathway nanoparticles increases with increasing concentration of ZnChl or water content in a MeOH/water solvent mixture. For a water content >90% deeply trapped off-pathway nanoparticle products are formed that do not transform anymore to the more ordered thermodynamic product within reasonable time scales. Based on these observations{,} we hypothesize that out-of-equilibrium aggregate structures of natural BChl dyes may also exist in the natural chlorosomes of green bacteria.}, author = {Ogi, Soichiro and Grzeszkiewicz, Charlotte and Würthner, Frank}, journal = {Chem. Sci.}, keywords = {organic}, month = {03}, number = 10, pages = {2768-2773}, publisher = {The Royal Society of Chemistry}, title = {Pathway complexity in the self-assembly of a zinc chlorin model system of natural bacteriochlorophyll J-aggregates}, volume = 9, year = 2018 }

  %0 Journal Article %1 C7SC03725B %A Ogi, Soichiro %A Grzeszkiewicz, Charlotte %A Würthner, Frank %D 2018 %I The Royal Society of Chemistry %J Chem. Sci. %N 10 %P 2768-2773 %R 10.1039/C7SC03725B %T Pathway complexity in the self-assembly of a zinc chlorin model system of natural bacteriochlorophyll J-aggregates %U http://dx.doi.org/10.1039/C7SC03725B %V 9 %X Whilst bacteriochlorophyll c, d, and e dyes self-assemble into the most efficient light harvesting J-aggregate systems found in nature, their supramolecular packing arrangements are still a matter of debate and a significant number of models have been suggested for their local and long-range ordering. Here we reveal for a synthetic model system based on a zinc chlorin (ZnChl) dye an intriguing interplay of two competing aggregation pathways by kinetic and thermodynamic studies in MeOH/water solvent mixtures: the formation of kinetically controlled off-pathway nanoparticles consisting of excitonically coupled J-dimers versus the formation of thermodynamically more stable one-dimensional helical fibers consisting of J-coupled extended aggregates. The higher order of the latter is evidenced by atomic force microscopy and a more narrow absorption spectrum of the J-aggregates. Based on a recently developed thermodynamic model that combines the cooperative K2-K growth model with a competing dimerization model, an energy landscape could be derived that describes the pathway complexity of this biomimetic system. Our studies reveal that the kinetic stability of the off-pathway nanoparticles increases with increasing concentration of ZnChl or water content in a MeOH/water solvent mixture. For a water content >90% deeply trapped off-pathway nanoparticle products are formed that do not transform anymore to the more ordered thermodynamic product within reasonable time scales. Based on these observations, we hypothesize that out-of-equilibrium aggregate structures of natural BChl dyes may also exist in the natural chlorosomes of green bacteria.
• Fluorescence quantum yields of dye aggregates: a showcase example based on self-assembled perylene bisimide dimers. Fennel, Franziska; Gershberg, Jana; Stolte, Matthias; Würthner, Frank. In Phys. Chem. Chem. Phys., 20(11), pp. 7612–7620. 2018.
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  Constituting an intermediate state of matter between molecules and solid state materials, dye aggregates can give important insights into functional properties. Despite the importance of fluorescence for many applications, it turns out that the conventional methods for quantum yield determination are not applicable to dye aggregates and so far no method has been introduced for the accurate determination of the fluorescence quantum yields of dye aggregates. Here we suggest two measurement routines for the quantum yield determination of strongly absorbing dye aggregates. Both methods provide the quantum yield of the aggregated species without the necessity of reaching a fully aggregated state, which is particularly important for the most common case imparted by the low association constants of [small pi]-[small pi]-stacking interactions. The routines are experimentally validated with two perylene bisimide dyes whose self-assembly is driven by the concerted interplay of hydrogen bonding and [small pi]-[small pi]-stacking interactions, leading to structurally well defined co-facially stacked dimers at intermediate concentrations and a further growth into larger H-aggregates at a higher concentration. Compared to other H-aggregates relatively high fluorescence quantum yields of up to 28% are found for both the co-facially stacked dimers and the larger H-aggregates.

  @article{C7CP07778E, abstract = {Constituting an intermediate state of matter between molecules and solid state materials{,} dye aggregates can give important insights into functional properties. Despite the importance of fluorescence for many applications{,} it turns out that the conventional methods for quantum yield determination are not applicable to dye aggregates and so far no method has been introduced for the accurate determination of the fluorescence quantum yields of dye aggregates. Here we suggest two measurement routines for the quantum yield determination of strongly absorbing dye aggregates. Both methods provide the quantum yield of the aggregated species without the necessity of reaching a fully aggregated state{,} which is particularly important for the most common case imparted by the low association constants of [small pi]-[small pi]-stacking interactions. The routines are experimentally validated with two perylene bisimide dyes whose self-assembly is driven by the concerted interplay of hydrogen bonding and [small pi]-[small pi]-stacking interactions{,} leading to structurally well defined co-facially stacked dimers at intermediate concentrations and a further growth into larger H-aggregates at a higher concentration. Compared to other H-aggregates relatively high fluorescence quantum yields of up to 28% are found for both the co-facially stacked dimers and the larger H-aggregates.}, author = {Fennel, Franziska and Gershberg, Jana and Stolte, Matthias and Würthner, Frank}, journal = {Phys. Chem. Chem. Phys.}, keywords = {organic}, month = {03}, number = 11, pages = {7612-7620}, publisher = {The Royal Society of Chemistry}, title = {Fluorescence quantum yields of dye aggregates: a showcase example based on self-assembled perylene bisimide dimers}, volume = 20, year = 2018 }

  %0 Journal Article %1 C7CP07778E %A Fennel, Franziska %A Gershberg, Jana %A Stolte, Matthias %A Würthner, Frank %D 2018 %I The Royal Society of Chemistry %J Phys. Chem. Chem. Phys. %N 11 %P 7612-7620 %R 10.1039/C7CP07778E %T Fluorescence quantum yields of dye aggregates: a showcase example based on self-assembled perylene bisimide dimers %U http://dx.doi.org/10.1039/C7CP07778E %V 20 %X Constituting an intermediate state of matter between molecules and solid state materials, dye aggregates can give important insights into functional properties. Despite the importance of fluorescence for many applications, it turns out that the conventional methods for quantum yield determination are not applicable to dye aggregates and so far no method has been introduced for the accurate determination of the fluorescence quantum yields of dye aggregates. Here we suggest two measurement routines for the quantum yield determination of strongly absorbing dye aggregates. Both methods provide the quantum yield of the aggregated species without the necessity of reaching a fully aggregated state, which is particularly important for the most common case imparted by the low association constants of [small pi]-[small pi]-stacking interactions. The routines are experimentally validated with two perylene bisimide dyes whose self-assembly is driven by the concerted interplay of hydrogen bonding and [small pi]-[small pi]-stacking interactions, leading to structurally well defined co-facially stacked dimers at intermediate concentrations and a further growth into larger H-aggregates at a higher concentration. Compared to other H-aggregates relatively high fluorescence quantum yields of up to 28% are found for both the co-facially stacked dimers and the larger H-aggregates.
• Temperature-Responsive Luminescent Solar Concentrators: Tuning Energy Transfer in a Liquid Crystalline Matrix. Sol, Jeroen A. H. P.; Dehm, Volker; Hecht, Reinhard; Würthner, Frank; Schenning, Albertus P. H. J.; Debije, Michael G. In Angew. Chem. Int. Ed., 57(4), pp. 1030–1033. 2018.
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  Temperature-responsive luminescent solar concentrators (LSCs) have been fabricated in which the Förster resonance energy transfer (FRET) between a donor–acceptor pair in a liquid crystalline solvent can be tuned. At room temperatures, the perylene bisimide (PBI) acceptor is aggregated and FRET is inactive; while after heating to a temperature above the isotropic phase of the liquid crystal solvent, the acceptor PBI completely dissolves and FRET is activated. This unusual temperature control over FRET was used to design a color-tunable LSC. The device has been shown to be highly stable towards consecutive heating and cooling cycles, making it an appealing device for harvesting otherwise unused solar energy.

  @article{ANIE:ANIE201710487, abstract = {Temperature-responsive luminescent solar concentrators (LSCs) have been fabricated in which the Förster resonance energy transfer (FRET) between a donor–acceptor pair in a liquid crystalline solvent can be tuned. At room temperatures, the perylene bisimide (PBI) acceptor is aggregated and FRET is inactive; while after heating to a temperature above the isotropic phase of the liquid crystal solvent, the acceptor PBI completely dissolves and FRET is activated. This unusual temperature control over FRET was used to design a color-tunable LSC. The device has been shown to be highly stable towards consecutive heating and cooling cycles, making it an appealing device for harvesting otherwise unused solar energy.}, author = {Sol, Jeroen A. H. P. and Dehm, Volker and Hecht, Reinhard and Würthner, Frank and Schenning, Albertus P. H. J. and Debije, Michael G.}, journal = {Angew. Chem. Int. Ed.}, keywords = {organic}, month = {01}, number = 4, pages = {1030–1033}, title = {Temperature-Responsive Luminescent Solar Concentrators: Tuning Energy Transfer in a Liquid Crystalline Matrix}, volume = 57, year = 2018 }

  %0 Journal Article %1 ANIE:ANIE201710487 %A Sol, Jeroen A. H. P. %A Dehm, Volker %A Hecht, Reinhard %A Würthner, Frank %A Schenning, Albertus P. H. J. %A Debije, Michael G. %D 2018 %J Angew. Chem. Int. Ed. %N 4 %P 1030--1033 %R 10.1002/anie.201710487 %T Temperature-Responsive Luminescent Solar Concentrators: Tuning Energy Transfer in a Liquid Crystalline Matrix %U http://dx.doi.org/10.1002/anie.201710487 %V 57 %X Temperature-responsive luminescent solar concentrators (LSCs) have been fabricated in which the Förster resonance energy transfer (FRET) between a donor–acceptor pair in a liquid crystalline solvent can be tuned. At room temperatures, the perylene bisimide (PBI) acceptor is aggregated and FRET is inactive; while after heating to a temperature above the isotropic phase of the liquid crystal solvent, the acceptor PBI completely dissolves and FRET is activated. This unusual temperature control over FRET was used to design a color-tunable LSC. The device has been shown to be highly stable towards consecutive heating and cooling cycles, making it an appealing device for harvesting otherwise unused solar energy.
• Optical Sensing of Aromatic Amino Acids and Dipeptides by a Crown‐Ether‐Functionalized Perylene Bisimide Fluorophore. Weißenstein, Annike; Saha‐Möller, Chantu R. Dr; Würthner, Frank Prof. Dr. In Chemistry - A European Journal, 24(31), pp. 8009–8016. 2018.
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  The host–guest binding properties of a fluorescent perylene bisimide (PBI) receptor equipped with crown ether were studied in detail with a series of aromatic amino acids and dipeptides by UV/Vis, fluorescence and NMR spectroscopy. Fluorescence titration experiments showed that electron‐rich aromatic amino acids and dipeptides strongly quench the fluorescence of the electron‐poor PBI host molecule. Benesi–Hildebrand plots of fluorescence titration data confirmed the formation of host–guest complexes with 1:2 stoichiometry. Binding constants determined by global analysis of UV/Vis and fluorescence titration experiments revealed values between 103 m−1 and 105 m−1 in acetonitrile/methanol (9:1) at 23 °C. These data showed that amino acid l‐Trp having an indole group and dipeptides containing this amino acid bind to the PBI receptor more strongly than other amino acids and dipeptides investigated here. For dipeptides containing l‐Trp or l‐Tyr, the binding strength is dependent on the distance between the ammonium group and the aromatic unit of the amino acids and dipeptides leading to a strong sensitivity for Ala‐Trp dipeptide. 1D and 2D NMR experiments also corroborated 1:2 host–guest complexation and indicated formation of two diastereomeric species of host–guest complexes. The studies have shown that a properly functionalized PBI fluorophore functions as a molecular probe for the optical sensing of aromatic amino acids and dipeptides.

  @article{weienstein2018optical, abstract = {The host–guest binding properties of a fluorescent perylene bisimide (PBI) receptor equipped with crown ether were studied in detail with a series of aromatic amino acids and dipeptides by UV/Vis, fluorescence and NMR spectroscopy. Fluorescence titration experiments showed that electron‐rich aromatic amino acids and dipeptides strongly quench the fluorescence of the electron‐poor PBI host molecule. Benesi–Hildebrand plots of fluorescence titration data confirmed the formation of host–guest complexes with 1:2 stoichiometry. Binding constants determined by global analysis of UV/Vis and fluorescence titration experiments revealed values between 103 m−1 and 105 m−1 in acetonitrile/methanol (9:1) at 23 °C. These data showed that amino acid l‐Trp having an indole group and dipeptides containing this amino acid bind to the PBI receptor more strongly than other amino acids and dipeptides investigated here. For dipeptides containing l‐Trp or l‐Tyr, the binding strength is dependent on the distance between the ammonium group and the aromatic unit of the amino acids and dipeptides leading to a strong sensitivity for Ala‐Trp dipeptide. 1D and 2D NMR experiments also corroborated 1:2 host–guest complexation and indicated formation of two diastereomeric species of host–guest complexes. The studies have shown that a properly functionalized PBI fluorophore functions as a molecular probe for the optical sensing of aromatic amino acids and dipeptides.}, author = {Weißenstein, Annike and Saha‐Möller, Chantu R. Dr and Würthner, Frank Prof. Dr.}, journal = {Chemistry - A European Journal}, keywords = {organic}, month = {06}, number = 31, pages = {8009-8016}, title = {Optical Sensing of Aromatic Amino Acids and Dipeptides by a Crown‐Ether‐Functionalized Perylene Bisimide Fluorophore}, volume = 24, year = 2018 }

  %0 Journal Article %1 weienstein2018optical %A Weißenstein, Annike %A Saha‐Möller, Chantu R. Dr %A Würthner, Frank Prof. Dr. %D 2018 %J Chemistry - A European Journal %N 31 %P 8009-8016 %R 10.1002/chem.201800870. %T Optical Sensing of Aromatic Amino Acids and Dipeptides by a Crown‐Ether‐Functionalized Perylene Bisimide Fluorophore %U https://onlinelibrary.wiley.com/doi/full/10.1002/chem.201800870 %V 24 %X The host–guest binding properties of a fluorescent perylene bisimide (PBI) receptor equipped with crown ether were studied in detail with a series of aromatic amino acids and dipeptides by UV/Vis, fluorescence and NMR spectroscopy. Fluorescence titration experiments showed that electron‐rich aromatic amino acids and dipeptides strongly quench the fluorescence of the electron‐poor PBI host molecule. Benesi–Hildebrand plots of fluorescence titration data confirmed the formation of host–guest complexes with 1:2 stoichiometry. Binding constants determined by global analysis of UV/Vis and fluorescence titration experiments revealed values between 103 m−1 and 105 m−1 in acetonitrile/methanol (9:1) at 23 °C. These data showed that amino acid l‐Trp having an indole group and dipeptides containing this amino acid bind to the PBI receptor more strongly than other amino acids and dipeptides investigated here. For dipeptides containing l‐Trp or l‐Tyr, the binding strength is dependent on the distance between the ammonium group and the aromatic unit of the amino acids and dipeptides leading to a strong sensitivity for Ala‐Trp dipeptide. 1D and 2D NMR experiments also corroborated 1:2 host–guest complexation and indicated formation of two diastereomeric species of host–guest complexes. The studies have shown that a properly functionalized PBI fluorophore functions as a molecular probe for the optical sensing of aromatic amino acids and dipeptides.
• Direct observation of exciton–exciton interactions. Dostál, Jakub; Fennel, Franziska; Koch, Federico; Herbst, Stefanie; Würthner, Frank; Brixner, Tobias. In Nature Communications, 9(1), pp. 2466–2473. 2018.
  • [ Abstract ]
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  Natural light harvesting as well as optoelectronic and photovoltaic devices depend on efficient transport of energy following photoexcitation. Using common spectroscopic methods, however, it is challenging to discriminate one-exciton dynamics from multi-exciton interactions that arise when more than one excitation is present in the system. Here we introduce a coherent two-dimensional spectroscopic method that provides a signal only in case that the presence of one exciton influences the behavior of another one. Exemplarily, we monitor exciton diffusion by annihilation in a perylene bisimide-based J-aggregate. We determine quantitatively the exciton diffusion constant from exciton–exciton-interaction 2D spectra and reconstruct the annihilation-free dynamics for large pump powers. The latter enables for ultrafast spectroscopy at much higher intensities than conventionally possible and thus improves signal-to-noise ratios for multichromophore systems; the former recovers spatio–temporal dynamics for a broad range of phenomena in which exciton interactions are present.

  @article{dostal2018direct, abstract = {Natural light harvesting as well as optoelectronic and photovoltaic devices depend on efficient transport of energy following photoexcitation. Using common spectroscopic methods, however, it is challenging to discriminate one-exciton dynamics from multi-exciton interactions that arise when more than one excitation is present in the system. Here we introduce a coherent two-dimensional spectroscopic method that provides a signal only in case that the presence of one exciton influences the behavior of another one. Exemplarily, we monitor exciton diffusion by annihilation in a perylene bisimide-based J-aggregate. We determine quantitatively the exciton diffusion constant from exciton–exciton-interaction 2D spectra and reconstruct the annihilation-free dynamics for large pump powers. The latter enables for ultrafast spectroscopy at much higher intensities than conventionally possible and thus improves signal-to-noise ratios for multichromophore systems; the former recovers spatio–temporal dynamics for a broad range of phenomena in which exciton interactions are present.}, author = {Dostál, Jakub and Fennel, Franziska and Koch, Federico and Herbst, Stefanie and Würthner, Frank and Brixner, Tobias}, journal = {Nature Communications}, keywords = {photovoltaic}, month = {06}, number = 1, pages = {2466–2473}, title = {Direct observation of exciton–exciton interactions}, volume = 9, year = 2018 }

  %0 Journal Article %1 dostal2018direct %A Dostál, Jakub %A Fennel, Franziska %A Koch, Federico %A Herbst, Stefanie %A Würthner, Frank %A Brixner, Tobias %D 2018 %J Nature Communications %N 1 %P 2466--2473 %R 10.1038/s41467-018-04884-4 %T Direct observation of exciton–exciton interactions %U https://doi.org/10.1038/s41467-018-04884-4 %V 9 %X Natural light harvesting as well as optoelectronic and photovoltaic devices depend on efficient transport of energy following photoexcitation. Using common spectroscopic methods, however, it is challenging to discriminate one-exciton dynamics from multi-exciton interactions that arise when more than one excitation is present in the system. Here we introduce a coherent two-dimensional spectroscopic method that provides a signal only in case that the presence of one exciton influences the behavior of another one. Exemplarily, we monitor exciton diffusion by annihilation in a perylene bisimide-based J-aggregate. We determine quantitatively the exciton diffusion constant from exciton–exciton-interaction 2D spectra and reconstruct the annihilation-free dynamics for large pump powers. The latter enables for ultrafast spectroscopy at much higher intensities than conventionally possible and thus improves signal-to-noise ratios for multichromophore systems; the former recovers spatio–temporal dynamics for a broad range of phenomena in which exciton interactions are present.
• Tetrachlorinated Polycyclic Aromatic Dicarboximides: New Electron‐Poor π‐Scaffolds and NIR Emitters by Palladium‐Catalyzed Annulation Reaction. Mahl, Magnus; Shoyama, Dr. Kazutaka; Rühe, Jessica; Grande, Dr. Vincenzo; Würthner, Prof. Frank. In Chemistry - A European Journal, 24(37), pp. 9409 –9416. 2018.
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  Herein we report a palladium-catalyzed annulation reaction consisting of a Suzuki–Miyaura cross-coupling and a C-H arylation cascade for the synthesis of tetrachlorinated polycyclic aromatic dicarboximides (PADIs). This convergent synthetic route afforded a broad series of hitherto unknown electron-deficient PADIs under optimized reaction conditions by coupling of a dibromo-tetrachloro-perylene dicarboximide with different polycyclic aromatic hydrocarbon (PAH) boronic acid pinacol esters in up to 89% yields. The new PADI compounds show broad absorption in the visible range and some of them emit in the near-infrared (NIR) region. Cyclic and square wave voltammetric studies revealed that these tetrachlorinated PADIs are more electrondeficient than a non-chlorinated reference compound and they possess lower lying frontier orbitals. Thus, the newly synthesized electron-poor PADIs are potential n-type semiconductors. Moreover, these chlorinated PADIs are interesting building blocks for the construction of large p-extended arrays by metal-mediated coupling reactions.

  @article{mahl2018tetrachlorinated, abstract = {Herein we report a palladium-catalyzed annulation reaction consisting of a Suzuki–Miyaura cross-coupling and a C-H arylation cascade for the synthesis of tetrachlorinated polycyclic aromatic dicarboximides (PADIs). This convergent synthetic route afforded a broad series of hitherto unknown electron-deficient PADIs under optimized reaction conditions by coupling of a dibromo-tetrachloro-perylene dicarboximide with different polycyclic aromatic hydrocarbon (PAH) boronic acid pinacol esters in up to 89% yields. The new PADI compounds show broad absorption in the visible range and some of them emit in the near-infrared (NIR) region. Cyclic and square wave voltammetric studies revealed that these tetrachlorinated PADIs are more electrondeficient than a non-chlorinated reference compound and they possess lower lying frontier orbitals. Thus, the newly synthesized electron-poor PADIs are potential n-type semiconductors. Moreover, these chlorinated PADIs are interesting building blocks for the construction of large p-extended arrays by metal-mediated coupling reactions.}, author = {Mahl, Magnus and Shoyama, Dr. Kazutaka and Rühe, Jessica and Grande, Dr. Vincenzo and Würthner, Prof. Frank}, journal = {Chemistry - A European Journal}, keywords = {organic}, month = {06}, number = 37, pages = {9409 –9416}, title = {Tetrachlorinated Polycyclic Aromatic Dicarboximides: New Electron‐Poor π‐Scaffolds and NIR Emitters by Palladium‐Catalyzed Annulation Reaction}, volume = 24, year = 2018 }

  %0 Journal Article %1 mahl2018tetrachlorinated %A Mahl, Magnus %A Shoyama, Dr. Kazutaka %A Rühe, Jessica %A Grande, Dr. Vincenzo %A Würthner, Prof. Frank %D 2018 %J Chemistry - A European Journal %N 37 %P 9409 –9416 %R DOI:10.1002/chem.201801191 %T Tetrachlorinated Polycyclic Aromatic Dicarboximides: New Electron‐Poor π‐Scaffolds and NIR Emitters by Palladium‐Catalyzed Annulation Reaction %U http://dx.doi.org/10.1002/chem.201801191 %V 24 %X Herein we report a palladium-catalyzed annulation reaction consisting of a Suzuki–Miyaura cross-coupling and a C-H arylation cascade for the synthesis of tetrachlorinated polycyclic aromatic dicarboximides (PADIs). This convergent synthetic route afforded a broad series of hitherto unknown electron-deficient PADIs under optimized reaction conditions by coupling of a dibromo-tetrachloro-perylene dicarboximide with different polycyclic aromatic hydrocarbon (PAH) boronic acid pinacol esters in up to 89% yields. The new PADI compounds show broad absorption in the visible range and some of them emit in the near-infrared (NIR) region. Cyclic and square wave voltammetric studies revealed that these tetrachlorinated PADIs are more electrondeficient than a non-chlorinated reference compound and they possess lower lying frontier orbitals. Thus, the newly synthesized electron-poor PADIs are potential n-type semiconductors. Moreover, these chlorinated PADIs are interesting building blocks for the construction of large p-extended arrays by metal-mediated coupling reactions.
• Crystal step edges can trap electrons on the surfaces of n-type organic semiconductors. He, Tao; Wu, Yanfei; D’Avino, Gabriele; Schmidt, Elliot; Stolte, Matthias; Cornil, Jérôme; Beljonne, David; Ruden, P. Paul; Würthner, Frank; Frisbie, C. Daniel. In Nature Communications, 9(1), p. 2141. 2018.
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  Understanding relationships between microstructure and electrical transport is an important goal for the materials science of organic semiconductors. Combining high-resolution surface potential mapping by scanning Kelvin probe microscopy (SKPM) with systematic field effect transport measurements, we show that step edges can trap electrons on the surfaces of single crystal organic semiconductors. n-type organic semiconductor crystals exhibiting positive step edge surface potentials display threshold voltages that increase and carrier mobilities that decrease with increasing step density, characteristic of trapping, whereas crystals that do not have positive step edge surface potentials do not have strongly step density dependent transport. A device model and microelectrostatics calculations suggest that trapping can be intrinsic to step edges for crystals of molecules with polar substituents. The results provide a unique example of a specific microstructure–charge trapping relationship and highlight the utility of surface potential imaging in combination with transport measurements as a productive strategy for uncovering microscopic structure–property relationships in organic semiconductors.

  @article{he2018crystal, abstract = {Understanding relationships between microstructure and electrical transport is an important goal for the materials science of organic semiconductors. Combining high-resolution surface potential mapping by scanning Kelvin probe microscopy (SKPM) with systematic field effect transport measurements, we show that step edges can trap electrons on the surfaces of single crystal organic semiconductors. n-type organic semiconductor crystals exhibiting positive step edge surface potentials display threshold voltages that increase and carrier mobilities that decrease with increasing step density, characteristic of trapping, whereas crystals that do not have positive step edge surface potentials do not have strongly step density dependent transport. A device model and microelectrostatics calculations suggest that trapping can be intrinsic to step edges for crystals of molecules with polar substituents. The results provide a unique example of a specific microstructure–charge trapping relationship and highlight the utility of surface potential imaging in combination with transport measurements as a productive strategy for uncovering microscopic structure–property relationships in organic semiconductors.}, author = {He, Tao and Wu, Yanfei and D’Avino, Gabriele and Schmidt, Elliot and Stolte, Matthias and Cornil, Jérôme and Beljonne, David and Ruden, P. Paul and Würthner, Frank and Frisbie, C. Daniel}, journal = {Nature Communications}, keywords = {organic}, month = {06}, number = 1, pages = 2141, title = {Crystal step edges can trap electrons on the surfaces of n-type organic semiconductors}, volume = 9, year = 2018 }

  %0 Journal Article %1 he2018crystal %A He, Tao %A Wu, Yanfei %A D’Avino, Gabriele %A Schmidt, Elliot %A Stolte, Matthias %A Cornil, Jérôme %A Beljonne, David %A Ruden, P. Paul %A Würthner, Frank %A Frisbie, C. Daniel %D 2018 %J Nature Communications %N 1 %P 2141 %R 10.1038/s41467-018-04479-z %T Crystal step edges can trap electrons on the surfaces of n-type organic semiconductors %U https://doi.org/10.1038/s41467-018-04479-z %V 9 %X Understanding relationships between microstructure and electrical transport is an important goal for the materials science of organic semiconductors. Combining high-resolution surface potential mapping by scanning Kelvin probe microscopy (SKPM) with systematic field effect transport measurements, we show that step edges can trap electrons on the surfaces of single crystal organic semiconductors. n-type organic semiconductor crystals exhibiting positive step edge surface potentials display threshold voltages that increase and carrier mobilities that decrease with increasing step density, characteristic of trapping, whereas crystals that do not have positive step edge surface potentials do not have strongly step density dependent transport. A device model and microelectrostatics calculations suggest that trapping can be intrinsic to step edges for crystals of molecules with polar substituents. The results provide a unique example of a specific microstructure–charge trapping relationship and highlight the utility of surface potential imaging in combination with transport measurements as a productive strategy for uncovering microscopic structure–property relationships in organic semiconductors.
• Microtubular Self-Assembly of Covalent Organic Frameworks. Gole, Bappaditya; Stepanenko, Vladimir; Rager, Sabrina; Grüne, Matthias; Medina, Dana D.; Bein, Thomas; Würthner, Frank; Beuerle, Florian. In Angew. Chem. Int. Ed., 57(3), pp. 846–850. 2018.
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  Despite significant progress in the synthesis of covalent organic frameworks (COFs), reports on the precise construction of template-free nano- and microstructures of such materials have been rare. In the quest for dye-containing porous materials, a novel conjugated framework DPP-TAPP-COF with an enhanced absorption capability up to λ=800 nm has been synthesized by utilizing reversible imine condensations between 5,10,15,20-tetrakis(4-aminophenyl)porphyrin (TAPP) and a diketopyrrolopyrrole (DPP) dialdehyde derivative. Surprisingly, the obtained COF exhibited spontaneous aggregation into hollow microtubular assemblies with outer and inner tube diameters of around 300 and 90 nm, respectively. A detailed mechanistic investigation revealed the time-dependent transformation of initial sheet-like agglomerates into the tubular microstructures.

  @article{ANIE:ANIE201708526, abstract = {Despite significant progress in the synthesis of covalent organic frameworks (COFs), reports on the precise construction of template-free nano- and microstructures of such materials have been rare. In the quest for dye-containing porous materials, a novel conjugated framework DPP-TAPP-COF with an enhanced absorption capability up to λ=800 nm has been synthesized by utilizing reversible imine condensations between 5,10,15,20-tetrakis(4-aminophenyl)porphyrin (TAPP) and a diketopyrrolopyrrole (DPP) dialdehyde derivative. Surprisingly, the obtained COF exhibited spontaneous aggregation into hollow microtubular assemblies with outer and inner tube diameters of around 300 and 90 nm, respectively. A detailed mechanistic investigation revealed the time-dependent transformation of initial sheet-like agglomerates into the tubular microstructures.}, author = {Gole, Bappaditya and Stepanenko, Vladimir and Rager, Sabrina and Grüne, Matthias and Medina, Dana D. and Bein, Thomas and Würthner, Frank and Beuerle, Florian}, journal = {Angew. Chem. Int. Ed.}, keywords = {organic}, month = {01}, number = 3, pages = {846–850}, title = {Microtubular Self-Assembly of Covalent Organic Frameworks}, volume = 57, year = 2018 }

  %0 Journal Article %1 ANIE:ANIE201708526 %A Gole, Bappaditya %A Stepanenko, Vladimir %A Rager, Sabrina %A Grüne, Matthias %A Medina, Dana D. %A Bein, Thomas %A Würthner, Frank %A Beuerle, Florian %D 2018 %J Angew. Chem. Int. Ed. %N 3 %P 846--850 %R 10.1002/anie.201708526 %T Microtubular Self-Assembly of Covalent Organic Frameworks %U http://dx.doi.org/10.1002/anie.201708526 %V 57 %X Despite significant progress in the synthesis of covalent organic frameworks (COFs), reports on the precise construction of template-free nano- and microstructures of such materials have been rare. In the quest for dye-containing porous materials, a novel conjugated framework DPP-TAPP-COF with an enhanced absorption capability up to λ=800 nm has been synthesized by utilizing reversible imine condensations between 5,10,15,20-tetrakis(4-aminophenyl)porphyrin (TAPP) and a diketopyrrolopyrrole (DPP) dialdehyde derivative. Surprisingly, the obtained COF exhibited spontaneous aggregation into hollow microtubular assemblies with outer and inner tube diameters of around 300 and 90 nm, respectively. A detailed mechanistic investigation revealed the time-dependent transformation of initial sheet-like agglomerates into the tubular microstructures.
• Selective parallel G-quadruplex recognition by a NIR-to-NIR two-photon squaraine. Grande, Vincenzo; Shen, Chia-An; Deiana, Marco; Dudek, Marta; Olesiak-Banska, Joanna; Matczyszyn, Katarzyna; Würthner, Frank. In Chemical Science, 9, pp. 8375–8381. 2018.
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  Fluorescence imaging probes for specific G-quadruplex (G4) conformations are of considerable interest in biomedical research. Herein, we present the synthesis and the binding properties of a new water-soluble near-infrared (NIR) amphiphilic squaraine dye (CAS-C1) which is capable of selective detection of parallel over non-parallel and non G4 topologies. The striking changes in its linear optical response upon binding to parallel G4s give rise to high fluorescence quantum yields (Φf ≈ 0.7) and one-photon molecular brightness in the far-red-NIR region. The outstanding recognition process of CAS-C1 for parallel G4s via end-stacking provides binding constants in the nanomolar regime (Kb = 107 to 108 M−1) awarding it as one of the most potent parallel G4 binders currently available. Moreover, the CAS-C1-parallel G4 system exhibits large two-photon absorption (TPA) cross-sections and molecular brightness in the second NIR biological transparency window (λ ≈ 1275 nm), making it an ideal candidate for NIR-to-NIR ultrasensitive two-photon procedures.

  @article{grande2018selective, abstract = {Fluorescence imaging probes for specific G-quadruplex (G4) conformations are of considerable interest in biomedical research. Herein, we present the synthesis and the binding properties of a new water-soluble near-infrared (NIR) amphiphilic squaraine dye (CAS-C1) which is capable of selective detection of parallel over non-parallel and non G4 topologies. The striking changes in its linear optical response upon binding to parallel G4s give rise to high fluorescence quantum yields (Φf ≈ 0.7) and one-photon molecular brightness in the far-red-NIR region. The outstanding recognition process of CAS-C1 for parallel G4s via end-stacking provides binding constants in the nanomolar regime (Kb = 107 to 108 M−1) awarding it as one of the most potent parallel G4 binders currently available. Moreover, the CAS-C1-parallel G4 system exhibits large two-photon absorption (TPA) cross-sections and molecular brightness in the second NIR biological transparency window (λ ≈ 1275 nm), making it an ideal candidate for NIR-to-NIR ultrasensitive two-photon procedures.}, author = {Grande, Vincenzo and Shen, Chia-An and Deiana, Marco and Dudek, Marta and Olesiak-Banska, Joanna and Matczyszyn, Katarzyna and Würthner, Frank}, journal = {Chemical Science}, keywords = {organic}, month = 11, pages = {8375 - 8381}, title = {Selective parallel G-quadruplex recognition by a NIR-to-NIR two-photon squaraine}, volume = 9, year = 2018 }

  %0 Journal Article %1 grande2018selective %A Grande, Vincenzo %A Shen, Chia-An %A Deiana, Marco %A Dudek, Marta %A Olesiak-Banska, Joanna %A Matczyszyn, Katarzyna %A Würthner, Frank %D 2018 %J Chemical Science %P 8375 - 8381 %R 10.1039/C8SC02882F %T Selective parallel G-quadruplex recognition by a NIR-to-NIR two-photon squaraine %V 9 %X Fluorescence imaging probes for specific G-quadruplex (G4) conformations are of considerable interest in biomedical research. Herein, we present the synthesis and the binding properties of a new water-soluble near-infrared (NIR) amphiphilic squaraine dye (CAS-C1) which is capable of selective detection of parallel over non-parallel and non G4 topologies. The striking changes in its linear optical response upon binding to parallel G4s give rise to high fluorescence quantum yields (Φf ≈ 0.7) and one-photon molecular brightness in the far-red-NIR region. The outstanding recognition process of CAS-C1 for parallel G4s via end-stacking provides binding constants in the nanomolar regime (Kb = 107 to 108 M−1) awarding it as one of the most potent parallel G4 binders currently available. Moreover, the CAS-C1-parallel G4 system exhibits large two-photon absorption (TPA) cross-sections and molecular brightness in the second NIR biological transparency window (λ ≈ 1275 nm), making it an ideal candidate for NIR-to-NIR ultrasensitive two-photon procedures.
• Tunable Light-Matter Hybridization in Open Organic Microcavities. Betzold, Simon; Herbst, Stefanie; Trichet, Aurelien A. P.; Smith, Jason M.; Würthner, Frank; Höfling, Sven; Dietrich, Christof P. In ACS Photonics, 5(1), pp. 90–94. 2018.
  • [ Abstract ]
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  Open microcavities represent a versatile cavity design that allows the external control of internal properties such as cavity thickness and mode detuning without changing the key parameters of the cavity itself, rendering them particularly interesting for light–matter interaction experiments. Here, we demonstrate the tunability of an open microcavity with an embedded active organic layer providing parallel alignment of molecular transition dipole moments as well as strong self-absorption inside the cavity. By decreasing the cavity thickness, we observe a transition from the weak coupling regime into the strong coupling regime evidenced by the onset of avoided crossing behavior between involved modes. This change of coupling mechanism is shown for 2D (planar) as well as 0D (hemispherical) cavities.

  @article{Betzold_2017, abstract = {Open microcavities represent a versatile cavity design that allows the external control of internal properties such as cavity thickness and mode detuning without changing the key parameters of the cavity itself, rendering them particularly interesting for light–matter interaction experiments. Here, we demonstrate the tunability of an open microcavity with an embedded active organic layer providing parallel alignment of molecular transition dipole moments as well as strong self-absorption inside the cavity. By decreasing the cavity thickness, we observe a transition from the weak coupling regime into the strong coupling regime evidenced by the onset of avoided crossing behavior between involved modes. This change of coupling mechanism is shown for 2D (planar) as well as 0D (hemispherical) cavities.}, author = {Betzold, Simon and Herbst, Stefanie and Trichet, Aurelien A. P. and Smith, Jason M. and Würthner, Frank and Höfling, Sven and Dietrich, Christof P.}, journal = {ACS Photonics}, keywords = {organic}, month = {01}, number = 1, pages = {90–94}, publisher = {American Chemical Society (ACS)}, title = {Tunable Light-Matter Hybridization in Open Organic Microcavities}, volume = 5, year = 2018 }

  %0 Journal Article %1 Betzold_2017 %A Betzold, Simon %A Herbst, Stefanie %A Trichet, Aurelien A. P. %A Smith, Jason M. %A Würthner, Frank %A Höfling, Sven %A Dietrich, Christof P. %D 2018 %I American Chemical Society (ACS) %J ACS Photonics %N 1 %P 90--94 %R 10.1021/acsphotonics.7b00552 %T Tunable Light-Matter Hybridization in Open Organic Microcavities %U https://doi.org/10.1021%2Facsphotonics.7b00552 %V 5 %X Open microcavities represent a versatile cavity design that allows the external control of internal properties such as cavity thickness and mode detuning without changing the key parameters of the cavity itself, rendering them particularly interesting for light–matter interaction experiments. Here, we demonstrate the tunability of an open microcavity with an embedded active organic layer providing parallel alignment of molecular transition dipole moments as well as strong self-absorption inside the cavity. By decreasing the cavity thickness, we observe a transition from the weak coupling regime into the strong coupling regime evidenced by the onset of avoided crossing behavior between involved modes. This change of coupling mechanism is shown for 2D (planar) as well as 0D (hemispherical) cavities.
• Perfluoroalkyltricyanoborate and Perfluoroalkylcyanofluoroborate Anions: Building Blocks for Low-Viscosity Ionic Liquids. Landmann, Johannes; Sprenger, Jan A. P.; Hennig, Philipp T.; Bertermann, Rüdiger; Grüne, Matthias; Würthner, Frank; Ignat’ev, Nikolai V.; Finze, Maik. In Chemistry – A European Journal, 24(3), pp. 608–623. 2018.
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  The potassium perfluoroalkyltricyanoborates K[CnF2 n+1B(CN)3] [n=1 (1 d), 2 (2 d)] and the potassium mono(perfluoroalkyl)cyanofluoroborates K[CnF2 n+1BF(CN)2] [n=1 (1 c), 2 (2 c)] and [CnF2 n+1BF2(CN)]− [n=1 (1 b), 2 (2 b), 3 (3 b), 4 (4 b)] are accessible with perfect selectivities on multi-gram scales starting from K[CnF2 n+1BF3] and Me3SiCN. The K+ salts are starting materials for the preparation of salts with organic cations, for example, [EMIm]+ (EMIm=1-ethyl-3-methylimidazolium). These [EMIm]+ salts are hydrophobic room-temperature ionic liquids (RTILs) that are thermally, chemically and electrochemically very robust, offering electrochemical windows up to 5.8 V. The RTILs described herein, exhibit very low viscosities with a minimum of 14.0 mPa s at 20 °C for [EMIm]1 c, low melting points down to −57 °C for [EMIm]2 b and extraordinary high conductivities up to 17.6 mS cm−1 at 20 °C for [EMIm]1 c. The combination of these properties makes these ILs promising materials for electrochemical devices as exemplified by the application of selected RTILs as component of electrolytes in dye-sensitised solar cells (DSSCs, Grätzel cells). The efficiency of the DSSCs was found to increase with a decreasing viscosity of the neat ionic liquid. In addition to the spectroscopic characterisation, single crystals of the potassium salts of the anions 1 b–d, 2 d, 3 b and 4 c as well as of [nBu4N]2 c have been studied by X-ray diffraction.

  @article{CHEM:CHEM201703685, abstract = {The potassium perfluoroalkyltricyanoborates K[CnF2 n+1B(CN)3] [n=1 (1 d), 2 (2 d)] and the potassium mono(perfluoroalkyl)cyanofluoroborates K[CnF2 n+1BF(CN)2] [n=1 (1 c), 2 (2 c)] and [CnF2 n+1BF2(CN)]− [n=1 (1 b), 2 (2 b), 3 (3 b), 4 (4 b)] are accessible with perfect selectivities on multi-gram scales starting from K[CnF2 n+1BF3] and Me3SiCN. The K+ salts are starting materials for the preparation of salts with organic cations, for example, [EMIm]+ (EMIm=1-ethyl-3-methylimidazolium). These [EMIm]+ salts are hydrophobic room-temperature ionic liquids (RTILs) that are thermally, chemically and electrochemically very robust, offering electrochemical windows up to 5.8 V. The RTILs described herein, exhibit very low viscosities with a minimum of 14.0 mPa s at 20 °C for [EMIm]1 c, low melting points down to −57 °C for [EMIm]2 b and extraordinary high conductivities up to 17.6 mS cm−1 at 20 °C for [EMIm]1 c. The combination of these properties makes these ILs promising materials for electrochemical devices as exemplified by the application of selected RTILs as component of electrolytes in dye-sensitised solar cells (DSSCs, Grätzel cells). The efficiency of the DSSCs was found to increase with a decreasing viscosity of the neat ionic liquid. In addition to the spectroscopic characterisation, single crystals of the potassium salts of the anions 1 b–d, 2 d, 3 b and 4 c as well as of [nBu4N]2 c have been studied by X-ray diffraction.}, author = {Landmann, Johannes and Sprenger, Jan A. P. and Hennig, Philipp T. and Bertermann, Rüdiger and Grüne, Matthias and Würthner, Frank and Ignat'ev, Nikolai V. and Finze, Maik}, journal = {Chemistry – A European Journal}, keywords = {organic}, month = {01}, number = 3, pages = {608–623}, title = {Perfluoroalkyltricyanoborate and Perfluoroalkylcyanofluoroborate Anions: Building Blocks for Low-Viscosity Ionic Liquids}, volume = 24, year = 2018 }

  %0 Journal Article %1 CHEM:CHEM201703685 %A Landmann, Johannes %A Sprenger, Jan A. P. %A Hennig, Philipp T. %A Bertermann, Rüdiger %A Grüne, Matthias %A Würthner, Frank %A Ignat'ev, Nikolai V. %A Finze, Maik %D 2018 %J Chemistry – A European Journal %N 3 %P 608--623 %R 10.1002/chem.201703685 %T Perfluoroalkyltricyanoborate and Perfluoroalkylcyanofluoroborate Anions: Building Blocks for Low-Viscosity Ionic Liquids %U http://dx.doi.org/10.1002/chem.201703685 %V 24 %X The potassium perfluoroalkyltricyanoborates K[CnF2 n+1B(CN)3] [n=1 (1 d), 2 (2 d)] and the potassium mono(perfluoroalkyl)cyanofluoroborates K[CnF2 n+1BF(CN)2] [n=1 (1 c), 2 (2 c)] and [CnF2 n+1BF2(CN)]− [n=1 (1 b), 2 (2 b), 3 (3 b), 4 (4 b)] are accessible with perfect selectivities on multi-gram scales starting from K[CnF2 n+1BF3] and Me3SiCN. The K+ salts are starting materials for the preparation of salts with organic cations, for example, [EMIm]+ (EMIm=1-ethyl-3-methylimidazolium). These [EMIm]+ salts are hydrophobic room-temperature ionic liquids (RTILs) that are thermally, chemically and electrochemically very robust, offering electrochemical windows up to 5.8 V. The RTILs described herein, exhibit very low viscosities with a minimum of 14.0 mPa s at 20 °C for [EMIm]1 c, low melting points down to −57 °C for [EMIm]2 b and extraordinary high conductivities up to 17.6 mS cm−1 at 20 °C for [EMIm]1 c. The combination of these properties makes these ILs promising materials for electrochemical devices as exemplified by the application of selected RTILs as component of electrolytes in dye-sensitised solar cells (DSSCs, Grätzel cells). The efficiency of the DSSCs was found to increase with a decreasing viscosity of the neat ionic liquid. In addition to the spectroscopic characterisation, single crystals of the potassium salts of the anions 1 b–d, 2 d, 3 b and 4 c as well as of [nBu4N]2 c have been studied by X-ray diffraction.

• Ultrafast isomerization in a difluoroboryl-coordinated molecular switch. Consani, Cristina; Berberich, Martin; Würthner, Frank; Brixner, Tobias. In Chemical Physics Letters, 683(Supplement C), pp. 83–90. 2017.

  Ahmed Zewail (1946-2016) Commemoration Issue of Chemical Physics Letters
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  Abstract Molecular switches based on light-induced isomerization cycles are promising materials for sensors and biomedical applications. Understanding the details of the isomerization photocycle and identifying the nuclear coordinates involved in the photoreaction are relevant topics. Here we characterize the cis→trans and trans→cis isomerization of a new type of BF2-coordinated azo-dye molecular switch by pump-probe spectroscopy. While cis→trans isomerization is ultrafast and proceeds via a conical intersection, the trans→cis photocycle is more complex and involves at least three reaction channels. Finally, we employ the vibrational wavepackets accompanying isomerization to infer information on the nuclear degrees of freedom involved in the photoreaction.

  @article{CONSANI201783, abstract = {Abstract Molecular switches based on light-induced isomerization cycles are promising materials for sensors and biomedical applications. Understanding the details of the isomerization photocycle and identifying the nuclear coordinates involved in the photoreaction are relevant topics. Here we characterize the cis→trans and trans→cis isomerization of a new type of BF2-coordinated azo-dye molecular switch by pump-probe spectroscopy. While cis→trans isomerization is ultrafast and proceeds via a conical intersection, the trans→cis photocycle is more complex and involves at least three reaction channels. Finally, we employ the vibrational wavepackets accompanying isomerization to infer information on the nuclear degrees of freedom involved in the photoreaction.}, author = {Consani, Cristina and Berberich, Martin and Würthner, Frank and Brixner, Tobias}, journal = {Chemical Physics Letters}, keywords = {spectroscopy,}, note = {Ahmed Zewail (1946-2016) Commemoration Issue of Chemical Physics Letters}, number = {Supplement C}, pages = {83 - 90}, title = {Ultrafast isomerization in a difluoroboryl-coordinated molecular switch}, volume = 683, year = 2017 }

  %0 Journal Article %1 CONSANI201783 %A Consani, Cristina %A Berberich, Martin %A Würthner, Frank %A Brixner, Tobias %D 2017 %J Chemical Physics Letters %N Supplement C %P 83 - 90 %R https://doi.org/10.1016/j.cplett.2017.03.023 %T Ultrafast isomerization in a difluoroboryl-coordinated molecular switch %U http://www.sciencedirect.com/science/article/pii/S0009261417302439 %V 683 %X Abstract Molecular switches based on light-induced isomerization cycles are promising materials for sensors and biomedical applications. Understanding the details of the isomerization photocycle and identifying the nuclear coordinates involved in the photoreaction are relevant topics. Here we characterize the cis→trans and trans→cis isomerization of a new type of BF2-coordinated azo-dye molecular switch by pump-probe spectroscopy. While cis→trans isomerization is ultrafast and proceeds via a conical intersection, the trans→cis photocycle is more complex and involves at least three reaction channels. Finally, we employ the vibrational wavepackets accompanying isomerization to infer information on the nuclear degrees of freedom involved in the photoreaction.
• Exciton Transport in Molecular Aggregates – From Natural Antennas to Synthetic Chromophore Systems. Brixner, Tobias; Hildner, Richard; Köhler, Jürgen; Lambert, Christoph; Würthner, Frank. In Advanced Energy Materials, 7(16), p. n/a-n/a. 2017.
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  The transport of excitation energy in molecular aggregates is of crucial importance for the function of organic optoelectronic devices and next-generation solar cells. First, this review summarizes the theoretical background of the nature of the electronically excited states of molecular aggregates. For these systems, the electronic interaction between the monomers leads to the formation of exciton states. This goes along with a shift of the excitation energies and a redistribution of the oscillator strength with respect to the monomers. Next, a brief overview is provided over experimental techniques that allow to study the properties of excitons in molecular aggregates. This includes single-molecule spectroscopy, coherent two-dimensional (2D) spectroscopy, and single-molecule coherent spectroscopy. Finally, examples of molecular aggregates spanning the range from natural systems that act in photosynthesis as light-harvesting antennas to artificial aggregates built from synthetic chromophores are illustrated.

  @article{AENM:AENM201700236, abstract = {The transport of excitation energy in molecular aggregates is of crucial importance for the function of organic optoelectronic devices and next-generation solar cells. First, this review summarizes the theoretical background of the nature of the electronically excited states of molecular aggregates. For these systems, the electronic interaction between the monomers leads to the formation of exciton states. This goes along with a shift of the excitation energies and a redistribution of the oscillator strength with respect to the monomers. Next, a brief overview is provided over experimental techniques that allow to study the properties of excitons in molecular aggregates. This includes single-molecule spectroscopy, coherent two-dimensional (2D) spectroscopy, and single-molecule coherent spectroscopy. Finally, examples of molecular aggregates spanning the range from natural systems that act in photosynthesis as light-harvesting antennas to artificial aggregates built from synthetic chromophores are illustrated.}, author = {Brixner, Tobias and Hildner, Richard and Köhler, Jürgen and Lambert, Christoph and Würthner, Frank}, journal = {Advanced Energy Materials}, keywords = {myown}, number = 16, pages = {n/a–n/a}, title = {Exciton Transport in Molecular Aggregates – From Natural Antennas to Synthetic Chromophore Systems}, volume = 7, year = 2017 }

  %0 Journal Article %1 AENM:AENM201700236 %A Brixner, Tobias %A Hildner, Richard %A Köhler, Jürgen %A Lambert, Christoph %A Würthner, Frank %D 2017 %J Advanced Energy Materials %N 16 %P n/a--n/a %R 10.1002/aenm.201700236 %T Exciton Transport in Molecular Aggregates – From Natural Antennas to Synthetic Chromophore Systems %U http://dx.doi.org/10.1002/aenm.201700236 %V 7 %X The transport of excitation energy in molecular aggregates is of crucial importance for the function of organic optoelectronic devices and next-generation solar cells. First, this review summarizes the theoretical background of the nature of the electronically excited states of molecular aggregates. For these systems, the electronic interaction between the monomers leads to the formation of exciton states. This goes along with a shift of the excitation energies and a redistribution of the oscillator strength with respect to the monomers. Next, a brief overview is provided over experimental techniques that allow to study the properties of excitons in molecular aggregates. This includes single-molecule spectroscopy, coherent two-dimensional (2D) spectroscopy, and single-molecule coherent spectroscopy. Finally, examples of molecular aggregates spanning the range from natural systems that act in photosynthesis as light-harvesting antennas to artificial aggregates built from synthetic chromophores are illustrated.
• Trinuclear Ruthenium Macrocycles: Toward Supramolecular Water Oxidation Catalysis in Pure Water. Kunz, Valentin; Schulze, Marcus; Schmidt, David; Würthner, Frank. In ACS Energy Letters, 2(2), pp. 288–293. 2017.
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  The incorporation of a Ru(bda)(bda = 2,2′-bipyridine-6,6′-dicarboxylate) water oxidation catalyst into a trinuclear metallosupramolecular macrocycle leads to increased stability and activity compared to the mononuclear reference system. To overcome solubility problems of such large structures in water and the need for large amounts of organic cosolvents, new macrocyclic water oxidation catalysts with improved water solubility become desirable. With triethylene glycol side chains, the required amount of acetonitrile as a cosolvent was halved, whereas the application of charged ammonium side chains allowed catalysis in pure water. The catalytic activity was found to be comparable to the parent compound. Kinetic experiments were performed to explain the rate differences between those new derivatives and showed that Coulombic repulsion between the charged side chains and CeIV leads to slower oxidation processes.

  @article{doi:10.1021/acsenergylett.6b00560, abstract = {The incorporation of a Ru(bda)(bda = 2,2′-bipyridine-6,6′-dicarboxylate) water oxidation catalyst into a trinuclear metallosupramolecular macrocycle leads to increased stability and activity compared to the mononuclear reference system. To overcome solubility problems of such large structures in water and the need for large amounts of organic cosolvents, new macrocyclic water oxidation catalysts with improved water solubility become desirable. With triethylene glycol side chains, the required amount of acetonitrile as a cosolvent was halved, whereas the application of charged ammonium side chains allowed catalysis in pure water. The catalytic activity was found to be comparable to the parent compound. Kinetic experiments were performed to explain the rate differences between those new derivatives and showed that Coulombic repulsion between the charged side chains and CeIV leads to slower oxidation processes.}, author = {Kunz, Valentin and Schulze, Marcus and Schmidt, David and Würthner, Frank}, journal = {ACS Energy Letters}, keywords = {myown}, number = 2, pages = {288-293}, title = {Trinuclear Ruthenium Macrocycles: Toward Supramolecular Water Oxidation Catalysis in Pure Water}, volume = 2, year = 2017 }

  %0 Journal Article %1 doi:10.1021/acsenergylett.6b00560 %A Kunz, Valentin %A Schulze, Marcus %A Schmidt, David %A Würthner, Frank %D 2017 %J ACS Energy Letters %N 2 %P 288-293 %R 10.1021/acsenergylett.6b00560 %T Trinuclear Ruthenium Macrocycles: Toward Supramolecular Water Oxidation Catalysis in Pure Water %U http://dx.doi.org/10.1021/acsenergylett.6b00560 %V 2 %X The incorporation of a Ru(bda)(bda = 2,2′-bipyridine-6,6′-dicarboxylate) water oxidation catalyst into a trinuclear metallosupramolecular macrocycle leads to increased stability and activity compared to the mononuclear reference system. To overcome solubility problems of such large structures in water and the need for large amounts of organic cosolvents, new macrocyclic water oxidation catalysts with improved water solubility become desirable. With triethylene glycol side chains, the required amount of acetonitrile as a cosolvent was halved, whereas the application of charged ammonium side chains allowed catalysis in pure water. The catalytic activity was found to be comparable to the parent compound. Kinetic experiments were performed to explain the rate differences between those new derivatives and showed that Coulombic repulsion between the charged side chains and CeIV leads to slower oxidation processes.
• Exciton Coupling of Merocyanine Dyes from H- to J-type in the Solid State by Crystal Engineering. Liess, Andreas; Lv, Aifeng; Arjona-Esteban, Alhama; Bialas, David; Krause, Ana-Maria; Stepanenko, Vladimir; Stolte, Matthias; Würthner, Frank. In Nano Letters, 17(3), pp. 1719–1726. 2017.

  PMID: 28165244
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  A key issue for the application of π-conjugated organic molecules as thin film solid-state materials is the packing structure, which drastically affects optical and electronic properties due to intermolecular coupling. In this regard, merocyanine dyes usually pack in H-coupled antiparallel arrangements while structures with more interesting J-type coupling have been rarely reported. Here we show that for three highly dipolar merocyanine dyes, which exhibit the same π-scaffold and accordingly equal properties as monomers in solution, the solid-state packing can be changed by a simple variation of aliphatic substituents to afford narrow and intense absorption bands with huge hypsochromic (H) or bathochromic (J) shifts for their thin films and nanocrystals. Time-dependent density functional theory calculations show that the energetic offset of almost 1 eV magnitude results from distinct packing motifs within the crystal structures that comply with the archetype H- or J-aggregate structures as described by Kasha’s exciton theory.

  @article{doi:10.1021/acs.nanolett.6b04995, abstract = {A key issue for the application of π-conjugated organic molecules as thin film solid-state materials is the packing structure, which drastically affects optical and electronic properties due to intermolecular coupling. In this regard, merocyanine dyes usually pack in H-coupled antiparallel arrangements while structures with more interesting J-type coupling have been rarely reported. Here we show that for three highly dipolar merocyanine dyes, which exhibit the same π-scaffold and accordingly equal properties as monomers in solution, the solid-state packing can be changed by a simple variation of aliphatic substituents to afford narrow and intense absorption bands with huge hypsochromic (H) or bathochromic (J) shifts for their thin films and nanocrystals. Time-dependent density functional theory calculations show that the energetic offset of almost 1 eV magnitude results from distinct packing motifs within the crystal structures that comply with the archetype H- or J-aggregate structures as described by Kasha’s exciton theory.}, author = {Liess, Andreas and Lv, Aifeng and Arjona-Esteban, Alhama and Bialas, David and Krause, Ana-Maria and Stepanenko, Vladimir and Stolte, Matthias and Würthner, Frank}, journal = {Nano Letters}, keywords = {myown}, note = {PMID: 28165244}, number = 3, pages = {1719-1726}, title = {Exciton Coupling of Merocyanine Dyes from H- to J-type in the Solid State by Crystal Engineering}, volume = 17, year = 2017 }

  %0 Journal Article %1 doi:10.1021/acs.nanolett.6b04995 %A Liess, Andreas %A Lv, Aifeng %A Arjona-Esteban, Alhama %A Bialas, David %A Krause, Ana-Maria %A Stepanenko, Vladimir %A Stolte, Matthias %A Würthner, Frank %D 2017 %J Nano Letters %N 3 %P 1719-1726 %R 10.1021/acs.nanolett.6b04995 %T Exciton Coupling of Merocyanine Dyes from H- to J-type in the Solid State by Crystal Engineering %U http://dx.doi.org/10.1021/acs.nanolett.6b04995 %V 17 %X A key issue for the application of π-conjugated organic molecules as thin film solid-state materials is the packing structure, which drastically affects optical and electronic properties due to intermolecular coupling. In this regard, merocyanine dyes usually pack in H-coupled antiparallel arrangements while structures with more interesting J-type coupling have been rarely reported. Here we show that for three highly dipolar merocyanine dyes, which exhibit the same π-scaffold and accordingly equal properties as monomers in solution, the solid-state packing can be changed by a simple variation of aliphatic substituents to afford narrow and intense absorption bands with huge hypsochromic (H) or bathochromic (J) shifts for their thin films and nanocrystals. Time-dependent density functional theory calculations show that the energetic offset of almost 1 eV magnitude results from distinct packing motifs within the crystal structures that comply with the archetype H- or J-aggregate structures as described by Kasha’s exciton theory.
• Cooperative water oxidation catalysis in a series of trinuclear metallosupramolecular ruthenium macrocycles. Kunz, Valentin; Lindner, Joachim O.; Schulze, Marcus; Rohr, Merle I. S.; Schmidt, David; Mitric, Roland; Würthner, Frank. In Energy Environ. Sci., 10(10), pp. 2137–2153. 2017.
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  A series of trinuclear metallosupramolecular Ru(bda) macrocycles has been synthesized and the impact of the ring size on the catalytic activity in homogeneous water oxidation has been elucidated (bda = 2,2[prime or minute]-bipyridine-6,6[prime or minute]-dicarboxylate). Kinetic experiments revealed that for all macrocyclic catalysts a proton-coupled oxidation event is rate-determining. Distinct H/D kinetic isotope effects (KIE) have been observed for the individual macrocycles, which follow the same tendency like the catalytic activity where an intermediate ring size exhibits the best performance. To get insight into the different molecular properties, molecular dynamics simulations using a QM/MM approach have been performed for all reaction steps, revealing that the size of the cavity strongly influences the hydrogen-bonded water network inside the macrocyclic structure and thus, important proton-coupled reaction steps of the catalytic cycle. For the most active catalysts, all reactive sites point into the interior of the cavity, which is supported by a single crystal X-ray analysis of the largest macrocycle, and a cooperative effect between the individual Ru(bda) centers facilitating proton abstraction has been substantiated. On the other hand, different structural conformations predominate the smaller macrocycles, which prevent efficient interactions between the Ru(bda) centers.

  @article{C7EE01557G, abstract = {A series of trinuclear metallosupramolecular Ru(bda) macrocycles has been synthesized and the impact of the ring size on the catalytic activity in homogeneous water oxidation has been elucidated (bda = 2{,}2[prime or minute]-bipyridine-6{,}6[prime or minute]-dicarboxylate). Kinetic experiments revealed that for all macrocyclic catalysts a proton-coupled oxidation event is rate-determining. Distinct H/D kinetic isotope effects (KIE) have been observed for the individual macrocycles{,} which follow the same tendency like the catalytic activity where an intermediate ring size exhibits the best performance. To get insight into the different molecular properties{,} molecular dynamics simulations using a QM/MM approach have been performed for all reaction steps{,} revealing that the size of the cavity strongly influences the hydrogen-bonded water network inside the macrocyclic structure and thus{,} important proton-coupled reaction steps of the catalytic cycle. For the most active catalysts{,} all reactive sites point into the interior of the cavity{,} which is supported by a single crystal X-ray analysis of the largest macrocycle{,} and a cooperative effect between the individual Ru(bda) centers facilitating proton abstraction has been substantiated. On the other hand{,} different structural conformations predominate the smaller macrocycles{,} which prevent efficient interactions between the Ru(bda) centers.}, author = {Kunz, Valentin and Lindner, Joachim O. and Schulze, Marcus and Rohr, Merle I. S. and Schmidt, David and Mitric, Roland and Würthner, Frank}, journal = {Energy Environ. Sci.}, keywords = {myown}, number = 10, pages = {2137-2153}, publisher = {The Royal Society of Chemistry}, title = {Cooperative water oxidation catalysis in a series of trinuclear metallosupramolecular ruthenium macrocycles}, volume = 10, year = 2017 }

  %0 Journal Article %1 C7EE01557G %A Kunz, Valentin %A Lindner, Joachim O. %A Schulze, Marcus %A Rohr, Merle I. S. %A Schmidt, David %A Mitric, Roland %A Würthner, Frank %D 2017 %I The Royal Society of Chemistry %J Energy Environ. Sci. %N 10 %P 2137-2153 %R 10.1039/C7EE01557G %T Cooperative water oxidation catalysis in a series of trinuclear metallosupramolecular ruthenium macrocycles %U http://dx.doi.org/10.1039/C7EE01557G %V 10 %X A series of trinuclear metallosupramolecular Ru(bda) macrocycles has been synthesized and the impact of the ring size on the catalytic activity in homogeneous water oxidation has been elucidated (bda = 2,2[prime or minute]-bipyridine-6,6[prime or minute]-dicarboxylate). Kinetic experiments revealed that for all macrocyclic catalysts a proton-coupled oxidation event is rate-determining. Distinct H/D kinetic isotope effects (KIE) have been observed for the individual macrocycles, which follow the same tendency like the catalytic activity where an intermediate ring size exhibits the best performance. To get insight into the different molecular properties, molecular dynamics simulations using a QM/MM approach have been performed for all reaction steps, revealing that the size of the cavity strongly influences the hydrogen-bonded water network inside the macrocyclic structure and thus, important proton-coupled reaction steps of the catalytic cycle. For the most active catalysts, all reactive sites point into the interior of the cavity, which is supported by a single crystal X-ray analysis of the largest macrocycle, and a cooperative effect between the individual Ru(bda) centers facilitating proton abstraction has been substantiated. On the other hand, different structural conformations predominate the smaller macrocycles, which prevent efficient interactions between the Ru(bda) centers.
• Diketopyrrolopyrrole Columnar Liquid-Crystalline Assembly Directed by Quadruple Hydrogen Bonds. Soberats, Bartolome; Hecht, Markus; Würthner, Frank. In Angew. Chem. Int. Ed., 56(36), pp. 10771–10774. 2017.
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  A diketopyrrolopyrrole (DPP) dye self-assembles via a unique hydrogen-bonding motif into an unprecedented columnar liquid-crystalline (LC) structure. X-ray and polarized FTIR experiments reveal that the DPPs organize into a one-dimensional assembly with the chromophores oriented parallel to the columnar axis. This columnar structure is composed of two π–π-stacked DPP dimers with mirror-image configurations that stack alternately through quadruple hydrogen bonding by 90° rotation. This exotic packing is dictated by the complementarity between H-bonds and the steric demands of the wedge-shaped groups attached at the core. This novel LC supramolecular material opens a new avenue of research on DPP dye assemblies with photofunctional properties tailored by H-bonding networks.

  @article{ANIE:ANIE201705137, abstract = {A diketopyrrolopyrrole (DPP) dye self-assembles via a unique hydrogen-bonding motif into an unprecedented columnar liquid-crystalline (LC) structure. X-ray and polarized FTIR experiments reveal that the DPPs organize into a one-dimensional assembly with the chromophores oriented parallel to the columnar axis. This columnar structure is composed of two π–π-stacked DPP dimers with mirror-image configurations that stack alternately through quadruple hydrogen bonding by 90° rotation. This exotic packing is dictated by the complementarity between H-bonds and the steric demands of the wedge-shaped groups attached at the core. This novel LC supramolecular material opens a new avenue of research on DPP dye assemblies with photofunctional properties tailored by H-bonding networks.}, author = {Soberats, Bartolome and Hecht, Markus and Würthner, Frank}, journal = {Angew. Chem. Int. Ed.}, keywords = {myown}, number = 36, pages = {10771–10774}, title = {Diketopyrrolopyrrole Columnar Liquid-Crystalline Assembly Directed by Quadruple Hydrogen Bonds}, volume = 56, year = 2017 }

  %0 Journal Article %1 ANIE:ANIE201705137 %A Soberats, Bartolome %A Hecht, Markus %A Würthner, Frank %D 2017 %J Angew. Chem. Int. Ed. %N 36 %P 10771--10774 %R 10.1002/anie.201705137 %T Diketopyrrolopyrrole Columnar Liquid-Crystalline Assembly Directed by Quadruple Hydrogen Bonds %U http://dx.doi.org/10.1002/anie.201705137 %V 56 %X A diketopyrrolopyrrole (DPP) dye self-assembles via a unique hydrogen-bonding motif into an unprecedented columnar liquid-crystalline (LC) structure. X-ray and polarized FTIR experiments reveal that the DPPs organize into a one-dimensional assembly with the chromophores oriented parallel to the columnar axis. This columnar structure is composed of two π–π-stacked DPP dimers with mirror-image configurations that stack alternately through quadruple hydrogen bonding by 90° rotation. This exotic packing is dictated by the complementarity between H-bonds and the steric demands of the wedge-shaped groups attached at the core. This novel LC supramolecular material opens a new avenue of research on DPP dye assemblies with photofunctional properties tailored by H-bonding networks.
• Hybrid Photoconductive Cathode Interlayer Materials Composed of Perylene Bisimide Photosensitizers and Zinc Oxide for High Performance Polymer Solar Cells. Xie, Zengqi; Würthner, Frank. In Advanced Energy Materials, 7(16), p. n/a-n/a. 2017.
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  Hybrid photoconductive materials based on zinc oxide (ZnO) doped with perylene bisimide (PBI) dye molecules have emerged as new promising cathode interlayer materials for inverted polymer solar cells (i-PSCs). Such interlayers show increased conductivity under light irradiation (working condition of i-PSCs) due to enhanced electron mobility and carrier density, enabling high performance devices at interlayer thickness of up to 100 nm. Such increased interlayer thickness is desired for roll-to-roll processing techniques to facilitate mass production of photovoltaic modules.

  @article{AENM:AENM201602573, abstract = {Hybrid photoconductive materials based on zinc oxide (ZnO) doped with perylene bisimide (PBI) dye molecules have emerged as new promising cathode interlayer materials for inverted polymer solar cells (i-PSCs). Such interlayers show increased conductivity under light irradiation (working condition of i-PSCs) due to enhanced electron mobility and carrier density, enabling high performance devices at interlayer thickness of up to 100 nm. Such increased interlayer thickness is desired for roll-to-roll processing techniques to facilitate mass production of photovoltaic modules.}, author = {Xie, Zengqi and Würthner, Frank}, journal = {Advanced Energy Materials}, keywords = {myown}, number = 16, pages = {n/a–n/a}, title = {Hybrid Photoconductive Cathode Interlayer Materials Composed of Perylene Bisimide Photosensitizers and Zinc Oxide for High Performance Polymer Solar Cells}, volume = 7, year = 2017 }

  %0 Journal Article %1 AENM:AENM201602573 %A Xie, Zengqi %A Würthner, Frank %D 2017 %J Advanced Energy Materials %N 16 %P n/a--n/a %R 10.1002/aenm.201602573 %T Hybrid Photoconductive Cathode Interlayer Materials Composed of Perylene Bisimide Photosensitizers and Zinc Oxide for High Performance Polymer Solar Cells %U http://dx.doi.org/10.1002/aenm.201602573 %V 7 %X Hybrid photoconductive materials based on zinc oxide (ZnO) doped with perylene bisimide (PBI) dye molecules have emerged as new promising cathode interlayer materials for inverted polymer solar cells (i-PSCs). Such interlayers show increased conductivity under light irradiation (working condition of i-PSCs) due to enhanced electron mobility and carrier density, enabling high performance devices at interlayer thickness of up to 100 nm. Such increased interlayer thickness is desired for roll-to-roll processing techniques to facilitate mass production of photovoltaic modules.
• A Crystalline π-Stack Containing Five Stereoisomers: Insights into Conformational Isomorphism, Chirality Inversion, and Disorder. Nowak-Król, Agnieszka; Röhr, Merle I. S.; Schmidt, David; Würthner, Frank. In Angew. Chem. Int. Ed., 56(39), pp. 11774–11778. 2017.
  • [ Abstract ]
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  An unprecedented crystal-packing arrangement of a tetramethoxy-bay-substituted perylene bisimide (PBI) consists of three crystallographically independent molecules, that is, an achiral (AC) PBI of saddle-shaped geometry along with two pairs of propeller-like twisted (P)- and (M)-enantiomeric PBI frameworks. All these five conformations are observed within a single π-stack revealing an intriguing packing sequence with an inversion of chirality from P to M via AC. Nudged elastic band calculations for the isolated molecule show that AC is a local minimum of the P to M interconversion path. In addition, two minor conformations were observed in the crystal, one of which resembles a transition-state molecule. Theoretical studies of dimeric and trimeric stacks reveal that the coexistence of all these structures in the crystal lattice is aided by the strong dispersion interactions between PBI cores and perfectly interdigitated dodecyl chains which stabilize energetically higher conformations.

  @article{ANIE:ANIE201705445, abstract = {An unprecedented crystal-packing arrangement of a tetramethoxy-bay-substituted perylene bisimide (PBI) consists of three crystallographically independent molecules, that is, an achiral (AC) PBI of saddle-shaped geometry along with two pairs of propeller-like twisted (P)- and (M)-enantiomeric PBI frameworks. All these five conformations are observed within a single π-stack revealing an intriguing packing sequence with an inversion of chirality from P to M via AC. Nudged elastic band calculations for the isolated molecule show that AC is a local minimum of the P to M interconversion path. In addition, two minor conformations were observed in the crystal, one of which resembles a transition-state molecule. Theoretical studies of dimeric and trimeric stacks reveal that the coexistence of all these structures in the crystal lattice is aided by the strong dispersion interactions between PBI cores and perfectly interdigitated dodecyl chains which stabilize energetically higher conformations.}, author = {Nowak-Król, Agnieszka and Röhr, Merle I. S. and Schmidt, David and Würthner, Frank}, journal = {Angew. Chem. Int. Ed.}, keywords = {myown}, number = 39, pages = {11774–11778}, title = {A Crystalline π-Stack Containing Five Stereoisomers: Insights into Conformational Isomorphism, Chirality Inversion, and Disorder}, volume = 56, year = 2017 }

  %0 Journal Article %1 ANIE:ANIE201705445 %A Nowak-Król, Agnieszka %A Röhr, Merle I. S. %A Schmidt, David %A Würthner, Frank %D 2017 %J Angew. Chem. Int. Ed. %N 39 %P 11774--11778 %R 10.1002/anie.201705445 %T A Crystalline π-Stack Containing Five Stereoisomers: Insights into Conformational Isomorphism, Chirality Inversion, and Disorder %U http://dx.doi.org/10.1002/anie.201705445 %V 56 %X An unprecedented crystal-packing arrangement of a tetramethoxy-bay-substituted perylene bisimide (PBI) consists of three crystallographically independent molecules, that is, an achiral (AC) PBI of saddle-shaped geometry along with two pairs of propeller-like twisted (P)- and (M)-enantiomeric PBI frameworks. All these five conformations are observed within a single π-stack revealing an intriguing packing sequence with an inversion of chirality from P to M via AC. Nudged elastic band calculations for the isolated molecule show that AC is a local minimum of the P to M interconversion path. In addition, two minor conformations were observed in the crystal, one of which resembles a transition-state molecule. Theoretical studies of dimeric and trimeric stacks reveal that the coexistence of all these structures in the crystal lattice is aided by the strong dispersion interactions between PBI cores and perfectly interdigitated dodecyl chains which stabilize energetically higher conformations.
• Perylene Bisimide Cyclophanes with High Binding Affinity for Large Planar Polycyclic Aromatic Hydrocarbons: Host–Guest Complexation versus Self-Encapsulation of Side Arms. Spenst, Peter; Sieblist, Andreas; Würthner, Frank. In Chemistry – A European Journal, 23(7), pp. 1667–1675. 2017.
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  Binding of guest molecules with high affinity and selectivity requires well-designed hosts to provide optimized interactions in the host–guest complexes. Herein we report the design and synthesis of new cyclophanes 2PBI(2,6-iPr)2 and 2PBI(2,6-Ph)2 based on core-disubstituted perylene bisimide (PBI) chromophores bearing two phenoxy bay-substituents that evoke almost planar PBI scaffolds. This strategy afforded the new cyclophanes with conformationally rigid cavities to ensure strong binding to stiff planar polycyclic aromatic hydrocarbons (PAHs). Our detailed host–guest binding studies with different PAHs by UV/Vis and fluorescence titration experiments revealed record binding strengths for PAHs with binding constants of up to 1.6×106 m−1 in chloroform at room temperature. One- and two-dimensional NMR experiments and solvent-dependent titration studies revealed self-encapsulation of the side arms of PBI bay-substituents into the cavities that attained high fluorescence quantum yields of these cyclophanes close to unity by preventing the interaction of PBI subunits in the excited states. The binding constants and Gibbs free energies of host–guest complexations disclosed significant effects of PBI bay-substituents and core twist on the binding affinity of the cyclophanes.

  @article{CHEM:CHEM201604875, abstract = {Binding of guest molecules with high affinity and selectivity requires well-designed hosts to provide optimized interactions in the host–guest complexes. Herein we report the design and synthesis of new cyclophanes 2PBI(2,6-iPr)2 and 2PBI(2,6-Ph)2 based on core-disubstituted perylene bisimide (PBI) chromophores bearing two phenoxy bay-substituents that evoke almost planar PBI scaffolds. This strategy afforded the new cyclophanes with conformationally rigid cavities to ensure strong binding to stiff planar polycyclic aromatic hydrocarbons (PAHs). Our detailed host–guest binding studies with different PAHs by UV/Vis and fluorescence titration experiments revealed record binding strengths for PAHs with binding constants of up to 1.6×106 m−1 in chloroform at room temperature. One- and two-dimensional NMR experiments and solvent-dependent titration studies revealed self-encapsulation of the side arms of PBI bay-substituents into the cavities that attained high fluorescence quantum yields of these cyclophanes close to unity by preventing the interaction of PBI subunits in the excited states. The binding constants and Gibbs free energies of host–guest complexations disclosed significant effects of PBI bay-substituents and core twist on the binding affinity of the cyclophanes.}, author = {Spenst, Peter and Sieblist, Andreas and Würthner, Frank}, journal = {Chemistry – A European Journal}, keywords = {myown}, number = 7, pages = {1667–1675}, title = {Perylene Bisimide Cyclophanes with High Binding Affinity for Large Planar Polycyclic Aromatic Hydrocarbons: Host–Guest Complexation versus Self-Encapsulation of Side Arms}, volume = 23, year = 2017 }

  %0 Journal Article %1 CHEM:CHEM201604875 %A Spenst, Peter %A Sieblist, Andreas %A Würthner, Frank %D 2017 %J Chemistry – A European Journal %N 7 %P 1667--1675 %R 10.1002/chem.201604875 %T Perylene Bisimide Cyclophanes with High Binding Affinity for Large Planar Polycyclic Aromatic Hydrocarbons: Host–Guest Complexation versus Self-Encapsulation of Side Arms %U http://dx.doi.org/10.1002/chem.201604875 %V 23 %X Binding of guest molecules with high affinity and selectivity requires well-designed hosts to provide optimized interactions in the host–guest complexes. Herein we report the design and synthesis of new cyclophanes 2PBI(2,6-iPr)2 and 2PBI(2,6-Ph)2 based on core-disubstituted perylene bisimide (PBI) chromophores bearing two phenoxy bay-substituents that evoke almost planar PBI scaffolds. This strategy afforded the new cyclophanes with conformationally rigid cavities to ensure strong binding to stiff planar polycyclic aromatic hydrocarbons (PAHs). Our detailed host–guest binding studies with different PAHs by UV/Vis and fluorescence titration experiments revealed record binding strengths for PAHs with binding constants of up to 1.6×106 m−1 in chloroform at room temperature. One- and two-dimensional NMR experiments and solvent-dependent titration studies revealed self-encapsulation of the side arms of PBI bay-substituents into the cavities that attained high fluorescence quantum yields of these cyclophanes close to unity by preventing the interaction of PBI subunits in the excited states. The binding constants and Gibbs free energies of host–guest complexations disclosed significant effects of PBI bay-substituents and core twist on the binding affinity of the cyclophanes.
• Fluorescence Polarization Measurements to Probe Alignment of a Bithiophene Dye in One-Dimensional Channels of Self-Assembled Phenylethynylene Bis-Urea Macrocycle Crystals. Kittikhunnatham, Preecha; Som, Bozumeh; Rassolov, Vitaly; Stolte, Matthias; Würthner, Frank; Shimizu, Linda S.; Greytak, Andrew B. In J. Phys. Chem. C., 121(33), pp. 18102–18109. 2017.
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  This paper describes the use of polarized fluorescence microscopy to directly probe guest molecule orientation in bis-urea macrocycle crystals. These macrocycles assemble to afford one-dimensional (1D) microchannels ∼9 Å in diameter that have previously been shown to exhibit normal Fickian diffusion and induce selective reactivity among the confined guest molecules. In the present work, we take advantage of the quasi-1D morphology of fiber-like microcrystals with the extended dimension corresponding to the channel axis to measure excitation and emission polarization values for a bithiophene guest. Guest fluorescence is shown to be polarized along the fiber axis with emission polarization values up to 0.729, indicating a high degree of orientational order within the 1D channels. The observed behavior is consistent with calculated results for the guest orientation and electronic transition dipole moment. The results indicate the value of functional fluorescent probes as a measure of guest confinement in low-dimensional environments.

  @article{doi:10.1021/acs.jpcc.7b07136, abstract = {This paper describes the use of polarized fluorescence microscopy to directly probe guest molecule orientation in bis-urea macrocycle crystals. These macrocycles assemble to afford one-dimensional (1D) microchannels ∼9 Å in diameter that have previously been shown to exhibit normal Fickian diffusion and induce selective reactivity among the confined guest molecules. In the present work, we take advantage of the quasi-1D morphology of fiber-like microcrystals with the extended dimension corresponding to the channel axis to measure excitation and emission polarization values for a bithiophene guest. Guest fluorescence is shown to be polarized along the fiber axis with emission polarization values up to 0.729, indicating a high degree of orientational order within the 1D channels. The observed behavior is consistent with calculated results for the guest orientation and electronic transition dipole moment. The results indicate the value of functional fluorescent probes as a measure of guest confinement in low-dimensional environments.}, author = {Kittikhunnatham, Preecha and Som, Bozumeh and Rassolov, Vitaly and Stolte, Matthias and Würthner, Frank and Shimizu, Linda S. and Greytak, Andrew B.}, journal = {J. Phys. Chem. C.}, keywords = {myown}, number = 33, pages = {18102-18109}, title = {Fluorescence Polarization Measurements to Probe Alignment of a Bithiophene Dye in One-Dimensional Channels of Self-Assembled Phenylethynylene Bis-Urea Macrocycle Crystals}, volume = 121, year = 2017 }

  %0 Journal Article %1 doi:10.1021/acs.jpcc.7b07136 %A Kittikhunnatham, Preecha %A Som, Bozumeh %A Rassolov, Vitaly %A Stolte, Matthias %A Würthner, Frank %A Shimizu, Linda S. %A Greytak, Andrew B. %D 2017 %J J. Phys. Chem. C. %N 33 %P 18102-18109 %R 10.1021/acs.jpcc.7b07136 %T Fluorescence Polarization Measurements to Probe Alignment of a Bithiophene Dye in One-Dimensional Channels of Self-Assembled Phenylethynylene Bis-Urea Macrocycle Crystals %U http://dx.doi.org/10.1021/acs.jpcc.7b07136 %V 121 %X This paper describes the use of polarized fluorescence microscopy to directly probe guest molecule orientation in bis-urea macrocycle crystals. These macrocycles assemble to afford one-dimensional (1D) microchannels ∼9 Å in diameter that have previously been shown to exhibit normal Fickian diffusion and induce selective reactivity among the confined guest molecules. In the present work, we take advantage of the quasi-1D morphology of fiber-like microcrystals with the extended dimension corresponding to the channel axis to measure excitation and emission polarization values for a bithiophene guest. Guest fluorescence is shown to be polarized along the fiber axis with emission polarization values up to 0.729, indicating a high degree of orientational order within the 1D channels. The observed behavior is consistent with calculated results for the guest orientation and electronic transition dipole moment. The results indicate the value of functional fluorescent probes as a measure of guest confinement in low-dimensional environments.
• Low temperature exciton dynamics and structural changes in perylene bisimide aggregates. Wolter, Steffen; Westphal, Karl Magnus; Hempel, Magdalena; Würthner, Frank; Kühn, Oliver; Lochbrunner, Stefan. In Journal of Physics B: Atomic, Molecular and Optical Physics, 50(18), p. 184005. 2017.
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  The temperature dependent exciton dynamics of J-aggregates formed by a perylene bisimide dye is investigated down to liquid nitrogen temperature (77 K) by femtosecond pump–probe spectroscopy. The analysis of the transient absorption data using a diffusion model for the excitons does not only reveal an overall decrease of the exciton mobility, but also a change in the dimensionality of the exciton transport at low temperatures. This change in dimensionality is further investigated by kinetic Monte Carlo simulations, identifying weakly interlinked one-dimensional aggregate chains as the most likely structure at low temperatures. This causes the exciton transport to be highly anisotropic.

  @article{0953-4075-50-18-184005, abstract = {The temperature dependent exciton dynamics of J-aggregates formed by a perylene bisimide dye is investigated down to liquid nitrogen temperature (77 K) by femtosecond pump–probe spectroscopy. The analysis of the transient absorption data using a diffusion model for the excitons does not only reveal an overall decrease of the exciton mobility, but also a change in the dimensionality of the exciton transport at low temperatures. This change in dimensionality is further investigated by kinetic Monte Carlo simulations, identifying weakly interlinked one-dimensional aggregate chains as the most likely structure at low temperatures. This causes the exciton transport to be highly anisotropic.}, author = {Wolter, Steffen and Westphal, Karl Magnus and Hempel, Magdalena and Würthner, Frank and Kühn, Oliver and Lochbrunner, Stefan}, journal = {Journal of Physics B: Atomic, Molecular and Optical Physics}, keywords = {myown}, number = 18, pages = 184005, title = {Low temperature exciton dynamics and structural changes in perylene bisimide aggregates}, volume = 50, year = 2017 }

  %0 Journal Article %1 0953-4075-50-18-184005 %A Wolter, Steffen %A Westphal, Karl Magnus %A Hempel, Magdalena %A Würthner, Frank %A Kühn, Oliver %A Lochbrunner, Stefan %D 2017 %J Journal of Physics B: Atomic, Molecular and Optical Physics %N 18 %P 184005 %T Low temperature exciton dynamics and structural changes in perylene bisimide aggregates %U http://stacks.iop.org/0953-4075/50/i=18/a=184005 %V 50 %X The temperature dependent exciton dynamics of J-aggregates formed by a perylene bisimide dye is investigated down to liquid nitrogen temperature (77 K) by femtosecond pump–probe spectroscopy. The analysis of the transient absorption data using a diffusion model for the excitons does not only reveal an overall decrease of the exciton mobility, but also a change in the dimensionality of the exciton transport at low temperatures. This change in dimensionality is further investigated by kinetic Monte Carlo simulations, identifying weakly interlinked one-dimensional aggregate chains as the most likely structure at low temperatures. This causes the exciton transport to be highly anisotropic.
• All-Polymer Photonic Microcavities Doped with Perylene Bisimide J-Aggregates. Lova, Paola; Grande, Vincenzo; Manfredi, Giovanni; Patrini, Maddalena; Herbst, Stefanie; Würthner, Frank; Comoretto, Davie. In Advanced Optical Materials, 5(21), p. 1700523. 2017.
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  Thanks to exciting chemical and optical features, perylene bisimide J-aggregates are ideal candidates to be employed for high-performance plastic photonic devices. However, they generally tend to form π–π stacked H-aggregates that are unsuitable for implementation in polymer resonant cavities. In this work, the efficient compatibilization of a tailored perylene bisimide forming robust J-aggregated supramolecular polymers into amorphous polypropylene is introduced. The new nanocomposite is then implemented into an all-polymer planar microcavity, which provides strong and directional spectral redistribution of the J-aggregate photoluminescence, due to a strong modification of the photonic states. A systematic analysis of the photoemitting processes, including photoluminescence decay and quantum yields, shows that the optical confinement in the polymeric microcavity does not introduce any additional nonradiative de-excitation pathways to those already found in the J-aggregate nanocomposite film and pave the way to PBI-based high-performance plastic photonic devices.

  @article{lova2017allpolymer, abstract = {Thanks to exciting chemical and optical features, perylene bisimide J-aggregates are ideal candidates to be employed for high-performance plastic photonic devices. However, they generally tend to form π–π stacked H-aggregates that are unsuitable for implementation in polymer resonant cavities. In this work, the efficient compatibilization of a tailored perylene bisimide forming robust J-aggregated supramolecular polymers into amorphous polypropylene is introduced. The new nanocomposite is then implemented into an all-polymer planar microcavity, which provides strong and directional spectral redistribution of the J-aggregate photoluminescence, due to a strong modification of the photonic states. A systematic analysis of the photoemitting processes, including photoluminescence decay and quantum yields, shows that the optical confinement in the polymeric microcavity does not introduce any additional nonradiative de-excitation pathways to those already found in the J-aggregate nanocomposite film and pave the way to PBI-based high-performance plastic photonic devices.}, author = {Lova, Paola and Grande, Vincenzo and Manfredi, Giovanni and Patrini, Maddalena and Herbst, Stefanie and Würthner, Frank and Comoretto, Davie}, journal = {Advanced Optical Materials}, keywords = {organic}, month = 11, number = 21, pages = 1700523, title = {All-Polymer Photonic Microcavities Doped with Perylene Bisimide J-Aggregates.}, volume = 5, year = 2017 }

  %0 Journal Article %1 lova2017allpolymer %A Lova, Paola %A Grande, Vincenzo %A Manfredi, Giovanni %A Patrini, Maddalena %A Herbst, Stefanie %A Würthner, Frank %A Comoretto, Davie %D 2017 %J Advanced Optical Materials %N 21 %P 1700523 %R 10.1002/adom.201700523 %T All-Polymer Photonic Microcavities Doped with Perylene Bisimide J-Aggregates. %U http://onlinelibrary.wiley.com/doi/10.1002/adom.201700523/abstract %V 5 %X Thanks to exciting chemical and optical features, perylene bisimide J-aggregates are ideal candidates to be employed for high-performance plastic photonic devices. However, they generally tend to form π–π stacked H-aggregates that are unsuitable for implementation in polymer resonant cavities. In this work, the efficient compatibilization of a tailored perylene bisimide forming robust J-aggregated supramolecular polymers into amorphous polypropylene is introduced. The new nanocomposite is then implemented into an all-polymer planar microcavity, which provides strong and directional spectral redistribution of the J-aggregate photoluminescence, due to a strong modification of the photonic states. A systematic analysis of the photoemitting processes, including photoluminescence decay and quantum yields, shows that the optical confinement in the polymeric microcavity does not introduce any additional nonradiative de-excitation pathways to those already found in the J-aggregate nanocomposite film and pave the way to PBI-based high-performance plastic photonic devices.
• Electron-Poor Bowl-Shaped Polycyclic Aromatic Dicarboximides: Synthesis, Crystal Structures, and Optical and Redox Properties. Shoyama, Kazutaka; Schmidt, David; Mahl, Magnus; Würthner, Frank. In Organic Letters, 19(19), pp. 5328–5331. 2017.

  PMID: 28901772
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  Two new bowl-shaped polycyclic aromatic hydrocarbons, based on corannulene and naphthalene dicarboximide, are synthesized by an improved Suzuki–Miyaura cross-coupling and C–H arylation cascade reaction. Crystallographic analyses confirm structural assignments and provide insight into molecular interactions in the solid state. The new bowl-shaped molecules show reversible oxidation and reduction, intense visible range absorption, and high fluorescence quantum yields. These molecules can be considered bowl-shaped congeners of planar perylene dicarboximides.

  @article{doi:10.1021/acs.orglett.7b02618, abstract = {Two new bowl-shaped polycyclic aromatic hydrocarbons, based on corannulene and naphthalene dicarboximide, are synthesized by an improved Suzuki–Miyaura cross-coupling and C–H arylation cascade reaction. Crystallographic analyses confirm structural assignments and provide insight into molecular interactions in the solid state. The new bowl-shaped molecules show reversible oxidation and reduction, intense visible range absorption, and high fluorescence quantum yields. These molecules can be considered bowl-shaped congeners of planar perylene dicarboximides.}, author = {Shoyama, Kazutaka and Schmidt, David and Mahl, Magnus and Würthner, Frank}, journal = {Organic Letters}, keywords = {myown}, note = {PMID: 28901772}, number = 19, pages = {5328-5331}, title = {Electron-Poor Bowl-Shaped Polycyclic Aromatic Dicarboximides: Synthesis, Crystal Structures, and Optical and Redox Properties}, volume = 19, year = 2017 }

  %0 Journal Article %1 doi:10.1021/acs.orglett.7b02618 %A Shoyama, Kazutaka %A Schmidt, David %A Mahl, Magnus %A Würthner, Frank %D 2017 %J Organic Letters %N 19 %P 5328-5331 %R 10.1021/acs.orglett.7b02618 %T Electron-Poor Bowl-Shaped Polycyclic Aromatic Dicarboximides: Synthesis, Crystal Structures, and Optical and Redox Properties %U http://dx.doi.org/10.1021/acs.orglett.7b02618 %V 19 %X Two new bowl-shaped polycyclic aromatic hydrocarbons, based on corannulene and naphthalene dicarboximide, are synthesized by an improved Suzuki–Miyaura cross-coupling and C–H arylation cascade reaction. Crystallographic analyses confirm structural assignments and provide insight into molecular interactions in the solid state. The new bowl-shaped molecules show reversible oxidation and reduction, intense visible range absorption, and high fluorescence quantum yields. These molecules can be considered bowl-shaped congeners of planar perylene dicarboximides.
• Supramolecular Approaches to Improve the Performance of Ruthenium-Based Water Oxidation Catalysts. Kunz, Valentin; Schmidt, David; Röhr, Merle I. S.; Mitrić, Roland; Würthner, Frank. In Advanced Energy Materials, 7(16), p. n/a-n/a. 2017.
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  Supramolecular principles have been widely applied to enhance the activity of homogeneous ruthenium-based water oxidation catalysts. For catalytic systems in which the OO bond is formed via radical coupling of two metal oxyl subunits, self-assembly of mononuclear catalysts into vesicles or fibrous aggregates can be used to improve the interaction of two catalytic centers. Similarly, the catalytic subunits can be brought into spatial proximity by coordination chemistry, which allows the construction of highly efficient metallosupramolecular multinuclear structures. However, if the OO bond is formed by the nucleophilic attack of water at a metal oxide species, the interaction of the catalytic center with substrate water molecules has to be improved. Here, by introducing tailored ligand systems, the second coordination sphere can be adjusted specifically to preorganize water for OO bond formation whereas the implementation of proton accepting residues can be used to lower the activation barrier of crucial proton-coupled reaction steps. In a particularly outstanding example, both principles were combined in a multinuclear metallosupramolecular macrocycle.

  @article{AENM:AENM201602939, abstract = {Supramolecular principles have been widely applied to enhance the activity of homogeneous ruthenium-based water oxidation catalysts. For catalytic systems in which the OO bond is formed via radical coupling of two metal oxyl subunits, self-assembly of mononuclear catalysts into vesicles or fibrous aggregates can be used to improve the interaction of two catalytic centers. Similarly, the catalytic subunits can be brought into spatial proximity by coordination chemistry, which allows the construction of highly efficient metallosupramolecular multinuclear structures. However, if the OO bond is formed by the nucleophilic attack of water at a metal oxide species, the interaction of the catalytic center with substrate water molecules has to be improved. Here, by introducing tailored ligand systems, the second coordination sphere can be adjusted specifically to preorganize water for OO bond formation whereas the implementation of proton accepting residues can be used to lower the activation barrier of crucial proton-coupled reaction steps. In a particularly outstanding example, both principles were combined in a multinuclear metallosupramolecular macrocycle.}, author = {Kunz, Valentin and Schmidt, David and Röhr, Merle I. S. and Mitrić, Roland and Würthner, Frank}, journal = {Advanced Energy Materials}, keywords = {myown}, number = 16, pages = {n/a–n/a}, title = {Supramolecular Approaches to Improve the Performance of Ruthenium-Based Water Oxidation Catalysts}, volume = 7, year = 2017 }

  %0 Journal Article %1 AENM:AENM201602939 %A Kunz, Valentin %A Schmidt, David %A Röhr, Merle I. S. %A Mitrić, Roland %A Würthner, Frank %D 2017 %J Advanced Energy Materials %N 16 %P n/a--n/a %R 10.1002/aenm.201602939 %T Supramolecular Approaches to Improve the Performance of Ruthenium-Based Water Oxidation Catalysts %U http://dx.doi.org/10.1002/aenm.201602939 %V 7 %X Supramolecular principles have been widely applied to enhance the activity of homogeneous ruthenium-based water oxidation catalysts. For catalytic systems in which the OO bond is formed via radical coupling of two metal oxyl subunits, self-assembly of mononuclear catalysts into vesicles or fibrous aggregates can be used to improve the interaction of two catalytic centers. Similarly, the catalytic subunits can be brought into spatial proximity by coordination chemistry, which allows the construction of highly efficient metallosupramolecular multinuclear structures. However, if the OO bond is formed by the nucleophilic attack of water at a metal oxide species, the interaction of the catalytic center with substrate water molecules has to be improved. Here, by introducing tailored ligand systems, the second coordination sphere can be adjusted specifically to preorganize water for OO bond formation whereas the implementation of proton accepting residues can be used to lower the activation barrier of crucial proton-coupled reaction steps. In a particularly outstanding example, both principles were combined in a multinuclear metallosupramolecular macrocycle.
• Atomistic Approach To Simulate Processes Relevant for the Efficiencies of Organic Solar Cells as a Function of Molecular Properties. II. Kinetic Aspects. Brückner, Charlotte; Würthner, Frank; Meerholz, Klaus; Engels, Bernd. In J. Phys. Chem. C., 121(1), pp. 26–51. 2017.
  • [ Abstract ]
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  The individual steps of the light-to-energy conversion process in the vicinity of the interfaces of organic solar cells are investigated with kinetic Monte Carlo simulations employing Marcus hopping rates obtained from quantum-chemical calculations. A chemically diverse set of p-type semiconducting molecules in heterojunction with fullerene C60 is used. Starting with exciton diffusion, exciton dissociation, charge generation, and charge separation are modeled on an atomistic level. Numerous aspects were already analyzed, but comprehensive simulations including all three processes in amorphous model interface systems and a comparison of various different molecular p-type semiconductors seem to be missing. Our investigation identifies several important kinetic effects that could limit device efficiencies, such as the strong reduction of charge transport rates in the vicinity of the interface due to Coulomb interactions between the charges, the importance of adjusting the relative rates of exciton transfer and dissociation, and the impact of morphology. Charge drift velocities and hole mobilities obtained from the simulations compare well with experimental values indicating that the main effects are covered by the simulations. A correlation between experimental short-circuit currents and simulated charge drift velocities suggests that slow charge-transfer processes could represent a major efficiency-limiting parameter in organic solar cells.

  @article{doi:10.1021/acs.jpcc.6b11340, abstract = {The individual steps of the light-to-energy conversion process in the vicinity of the interfaces of organic solar cells are investigated with kinetic Monte Carlo simulations employing Marcus hopping rates obtained from quantum-chemical calculations. A chemically diverse set of p-type semiconducting molecules in heterojunction with fullerene C60 is used. Starting with exciton diffusion, exciton dissociation, charge generation, and charge separation are modeled on an atomistic level. Numerous aspects were already analyzed, but comprehensive simulations including all three processes in amorphous model interface systems and a comparison of various different molecular p-type semiconductors seem to be missing. Our investigation identifies several important kinetic effects that could limit device efficiencies, such as the strong reduction of charge transport rates in the vicinity of the interface due to Coulomb interactions between the charges, the importance of adjusting the relative rates of exciton transfer and dissociation, and the impact of morphology. Charge drift velocities and hole mobilities obtained from the simulations compare well with experimental values indicating that the main effects are covered by the simulations. A correlation between experimental short-circuit currents and simulated charge drift velocities suggests that slow charge-transfer processes could represent a major efficiency-limiting parameter in organic solar cells.}, author = {Brückner, Charlotte and Würthner, Frank and Meerholz, Klaus and Engels, Bernd}, journal = {J. Phys. Chem. C.}, keywords = {myown}, number = 1, pages = {26-51}, title = {Atomistic Approach To Simulate Processes Relevant for the Efficiencies of Organic Solar Cells as a Function of Molecular Properties. II. Kinetic Aspects}, volume = 121, year = 2017 }

  %0 Journal Article %1 doi:10.1021/acs.jpcc.6b11340 %A Brückner, Charlotte %A Würthner, Frank %A Meerholz, Klaus %A Engels, Bernd %D 2017 %J J. Phys. Chem. C. %N 1 %P 26-51 %R 10.1021/acs.jpcc.6b11340 %T Atomistic Approach To Simulate Processes Relevant for the Efficiencies of Organic Solar Cells as a Function of Molecular Properties. II. Kinetic Aspects %U http://dx.doi.org/10.1021/acs.jpcc.6b11340 %V 121 %X The individual steps of the light-to-energy conversion process in the vicinity of the interfaces of organic solar cells are investigated with kinetic Monte Carlo simulations employing Marcus hopping rates obtained from quantum-chemical calculations. A chemically diverse set of p-type semiconducting molecules in heterojunction with fullerene C60 is used. Starting with exciton diffusion, exciton dissociation, charge generation, and charge separation are modeled on an atomistic level. Numerous aspects were already analyzed, but comprehensive simulations including all three processes in amorphous model interface systems and a comparison of various different molecular p-type semiconductors seem to be missing. Our investigation identifies several important kinetic effects that could limit device efficiencies, such as the strong reduction of charge transport rates in the vicinity of the interface due to Coulomb interactions between the charges, the importance of adjusting the relative rates of exciton transfer and dissociation, and the impact of morphology. Charge drift velocities and hole mobilities obtained from the simulations compare well with experimental values indicating that the main effects are covered by the simulations. A correlation between experimental short-circuit currents and simulated charge drift velocities suggests that slow charge-transfer processes could represent a major efficiency-limiting parameter in organic solar cells.
• QM/MM calculations combined with the dimer approach on the static disorder at organic-organic interfaces of thin-film organic solar cells composed of small molecules. Brückner, Charlotte; Stolte, Matthias; Würthner, Frank; Pflaum, Jens; Engels, Bernd. In J. Phys. Org. Chem. 2017.
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  A QM/MM approach using ωB97X-D combined with AMOEBA calculations was used to analyze the energetic disorder in the vicinity of interfaces in amorphous organic heterostructures. Distributions of ground-, excited-, and cationic-state energies as well as of ionization potentials and excitation energies, all being relevant quantities for the transport properties of thin films, were calculated. As already found for bulk amorphous organic semiconductors, local densities of states at molecular interfaces possess Gaussian-shaped profiles with a significant amount of disorder. Assuming a disorder-limited activation of exciton and charge transport, a decrease in the amount of disorder could improve the transport properties. Relating calculated disorders to molecular parameters revealed that in line with the Bässler model, especially the molecular polarity, its change upon electronic excitation, and the molecular polarizability are relevant quantities leading to energetically largely disordered films. Moreover, because of the different mechanisms of exciton and polaron delocalization, a given morphology with disordered charge-transport levels gives not necessarily rise to disordered exciton-transport levels and vice versa.

  @article{noauthororeditor2017calculations, abstract = {A QM/MM approach using ωB97X-D combined with AMOEBA calculations was used to analyze the energetic disorder in the vicinity of interfaces in amorphous organic heterostructures. Distributions of ground-, excited-, and cationic-state energies as well as of ionization potentials and excitation energies, all being relevant quantities for the transport properties of thin films, were calculated. As already found for bulk amorphous organic semiconductors, local densities of states at molecular interfaces possess Gaussian-shaped profiles with a significant amount of disorder. Assuming a disorder-limited activation of exciton and charge transport, a decrease in the amount of disorder could improve the transport properties. Relating calculated disorders to molecular parameters revealed that in line with the Bässler model, especially the molecular polarity, its change upon electronic excitation, and the molecular polarizability are relevant quantities leading to energetically largely disordered films. Moreover, because of the different mechanisms of exciton and polaron delocalization, a given morphology with disordered charge-transport levels gives not necessarily rise to disordered exciton-transport levels and vice versa.}, author = {Brückner, Charlotte and Stolte, Matthias and Würthner, Frank and Pflaum, Jens and Engels, Bernd}, journal = {J. Phys. Org. Chem.}, keywords = {organic}, month = {09}, title = {QM/MM calculations combined with the dimer approach on the static disorder at organic-organic interfaces of thin-film organic solar cells composed of small molecules.}, year = 2017 }

  %0 Journal Article %1 noauthororeditor2017calculations %A Brückner, Charlotte %A Stolte, Matthias %A Würthner, Frank %A Pflaum, Jens %A Engels, Bernd %D 2017 %J J. Phys. Org. Chem. %R 10.1002/poc.3740 %T QM/MM calculations combined with the dimer approach on the static disorder at organic-organic interfaces of thin-film organic solar cells composed of small molecules. %U http://onlinelibrary.wiley.com/doi/10.1002/poc.3740/full %X A QM/MM approach using ωB97X-D combined with AMOEBA calculations was used to analyze the energetic disorder in the vicinity of interfaces in amorphous organic heterostructures. Distributions of ground-, excited-, and cationic-state energies as well as of ionization potentials and excitation energies, all being relevant quantities for the transport properties of thin films, were calculated. As already found for bulk amorphous organic semiconductors, local densities of states at molecular interfaces possess Gaussian-shaped profiles with a significant amount of disorder. Assuming a disorder-limited activation of exciton and charge transport, a decrease in the amount of disorder could improve the transport properties. Relating calculated disorders to molecular parameters revealed that in line with the Bässler model, especially the molecular polarity, its change upon electronic excitation, and the molecular polarizability are relevant quantities leading to energetically largely disordered films. Moreover, because of the different mechanisms of exciton and polaron delocalization, a given morphology with disordered charge-transport levels gives not necessarily rise to disordered exciton-transport levels and vice versa.
• Evaluation of Perylene Bisimide-Based RuII and IrIII Complexes as Photosensitizers for Photodynamic Therapy. Mari, Cristina; Huang, Huaiyi; Rubbiani, Riccardo; Schulze, Marcus; Würthner, Frank; Chao, Hui; Gasser, Gilles. In European Journal of Inorganic Chemistry, 2017(12), pp. 1745–1752. 2017.
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  The synergistic action of a photosensitizer (PS), light, and oxygen is exploited in photodynamic therapy (PDT) to kill cancer cells with reduced side-effects compared with traditional chemotherapeutic treatments. In this regard, new PSs are still necessary to improve the efficacy and the outcomes of this medical technique. Over the past years, metal complexes have attracted interest as alternatives to traditional porphyrin and phthalocyanin-based PSs because of their tunable and thus tailor-made photophysical properties. Among others, RuII and IrIII derivatives have shown promising results. Here, we report on the investigation of [Ru(bpy)2(ab-PBI)][PF6]2 (1) and [Cp*Ir(ab-PBI)Cl]PF6 (2), where bpy = 2,2′-bipyridine, ab-PBI = azabenz-annulated perylene bisimide, and Cp* = pentamethylcyclopentadiene, as potential PDT PSs. These compounds display good photostability, as well as interesting singlet oxygen generation upon irradiation at 420 nm (in particular 2). Their biological activity was evaluated on four cell lines and, although the cytotoxicity of 1 did not improve significantly upon light irradiation, 2, which localizes in mitochondria of HeLa cells as indicated by ICP-MS measurements, reached nanomolar IC50 values on all the cell lines tested when activated with 420 nm light in low doses (9.27 J cm–2).

  @article{EJIC:EJIC201600516, abstract = {The synergistic action of a photosensitizer (PS), light, and oxygen is exploited in photodynamic therapy (PDT) to kill cancer cells with reduced side-effects compared with traditional chemotherapeutic treatments. In this regard, new PSs are still necessary to improve the efficacy and the outcomes of this medical technique. Over the past years, metal complexes have attracted interest as alternatives to traditional porphyrin and phthalocyanin-based PSs because of their tunable and thus tailor-made photophysical properties. Among others, RuII and IrIII derivatives have shown promising results. Here, we report on the investigation of [Ru(bpy)2(ab-PBI)][PF6]2 (1) and [Cp*Ir(ab-PBI)Cl]PF6 (2), where bpy = 2,2′-bipyridine, ab-PBI = azabenz-annulated perylene bisimide, and Cp* = pentamethylcyclopentadiene, as potential PDT PSs. These compounds display good photostability, as well as interesting singlet oxygen generation upon irradiation at 420 nm (in particular 2). Their biological activity was evaluated on four cell lines and, although the cytotoxicity of 1 did not improve significantly upon light irradiation, 2, which localizes in mitochondria of HeLa cells as indicated by ICP-MS measurements, reached nanomolar IC50 values on all the cell lines tested when activated with 420 nm light in low doses (9.27 J cm–2).}, author = {Mari, Cristina and Huang, Huaiyi and Rubbiani, Riccardo and Schulze, Marcus and Würthner, Frank and Chao, Hui and Gasser, Gilles}, journal = {European Journal of Inorganic Chemistry}, keywords = {myown}, number = 12, pages = {1745–1752}, title = {Evaluation of Perylene Bisimide-Based RuII and IrIII Complexes as Photosensitizers for Photodynamic Therapy}, volume = 2017, year = 2017 }

  %0 Journal Article %1 EJIC:EJIC201600516 %A Mari, Cristina %A Huang, Huaiyi %A Rubbiani, Riccardo %A Schulze, Marcus %A Würthner, Frank %A Chao, Hui %A Gasser, Gilles %D 2017 %J European Journal of Inorganic Chemistry %N 12 %P 1745--1752 %R 10.1002/ejic.201600516 %T Evaluation of Perylene Bisimide-Based RuII and IrIII Complexes as Photosensitizers for Photodynamic Therapy %U http://dx.doi.org/10.1002/ejic.201600516 %V 2017 %X The synergistic action of a photosensitizer (PS), light, and oxygen is exploited in photodynamic therapy (PDT) to kill cancer cells with reduced side-effects compared with traditional chemotherapeutic treatments. In this regard, new PSs are still necessary to improve the efficacy and the outcomes of this medical technique. Over the past years, metal complexes have attracted interest as alternatives to traditional porphyrin and phthalocyanin-based PSs because of their tunable and thus tailor-made photophysical properties. Among others, RuII and IrIII derivatives have shown promising results. Here, we report on the investigation of [Ru(bpy)2(ab-PBI)][PF6]2 (1) and [Cp*Ir(ab-PBI)Cl]PF6 (2), where bpy = 2,2′-bipyridine, ab-PBI = azabenz-annulated perylene bisimide, and Cp* = pentamethylcyclopentadiene, as potential PDT PSs. These compounds display good photostability, as well as interesting singlet oxygen generation upon irradiation at 420 nm (in particular 2). Their biological activity was evaluated on four cell lines and, although the cytotoxicity of 1 did not improve significantly upon light irradiation, 2, which localizes in mitochondria of HeLa cells as indicated by ICP-MS measurements, reached nanomolar IC50 values on all the cell lines tested when activated with 420 nm light in low doses (9.27 J cm–2).
• Unprecedented low energy losses in organic solar cells with high external quantum efficiencies by employing non-fullerene electron acceptors. Mishra, Amaresh; Keshtov, Mukhamed[space]L.; Looser, Annika; Singhal, Rahul; Stolte, Matthias; Würthner, Frank; Bauerle, Peter; Sharma, Ganesh D. In J. Mater. Chem. A, 5(28), pp. 14887–14897. 2017.
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  In order to realize high photocurrent generation in the low-energy region of the solar spectrum, two conjugated A-D-A oligomers, PY-1 and DCI-2 comprising a central dithieno[3,2-b:2[prime or minute],3[prime or minute]-d]pyrrole donor (D) unit and end-capping acceptors (A) 1-butyl-4-methyl-2,6-dioxopyridine-3-carbonitrile (PY) or 3-dicyanomethyleneindan-1-one (DCI) have been synthesized and characterized. The oligomers showed strong absorptions in the red and near-IR region in solution and in the solid state. As a consequence of the strong electron-accepting character, the absorption band of DCI-2 in thin films is significantly red-shifted compared to that of PY-1 resulting in a low optical energy gap of 1.23 eV. In optimized solution-processed bulk-heterojunction solar cells using a polymeric donor P1, the new non-fullerene acceptor DCI-2 provides an excellent power conversion efficiency of 6.94% which is noticeably higher than that of PY-1-based devices (PCE = 4.89%). Most importantly, a high open-circuit voltage (VOC) of [similar]0.8 V with unprecedented energy losses, between the optical energy gap and the open-circuit voltage, between 0.39 and 0.43 eV concomitant with excellent external quantum efficiencies of 69%@880 nm in the NIR-regime have been achieved for DCI-2-based devices.

  @article{C7TA04703G, abstract = {In order to realize high photocurrent generation in the low-energy region of the solar spectrum{,} two conjugated A-D-A oligomers{,} PY-1 and DCI-2 comprising a central dithieno[3{,}2-b:2[prime or minute]{,}3[prime or minute]-d]pyrrole donor (D) unit and end-capping acceptors (A) 1-butyl-4-methyl-2{,}6-dioxopyridine-3-carbonitrile (PY) or 3-dicyanomethyleneindan-1-one (DCI) have been synthesized and characterized. The oligomers showed strong absorptions in the red and near-IR region in solution and in the solid state. As a consequence of the strong electron-accepting character{,} the absorption band of DCI-2 in thin films is significantly red-shifted compared to that of PY-1 resulting in a low optical energy gap of 1.23 eV. In optimized solution-processed bulk-heterojunction solar cells using a polymeric donor P1{,} the new non-fullerene acceptor DCI-2 provides an excellent power conversion efficiency of 6.94% which is noticeably higher than that of PY-1-based devices (PCE = 4.89%). Most importantly{,} a high open-circuit voltage (VOC) of [similar]0.8 V with unprecedented energy losses{,} between the optical energy gap and the open-circuit voltage{,} between 0.39 and 0.43 eV concomitant with excellent external quantum efficiencies of 69%@880 nm in the NIR-regime have been achieved for DCI-2-based devices.}, author = {Mishra, Amaresh and Keshtov, Mukhamed[space]L. and Looser, Annika and Singhal, Rahul and Stolte, Matthias and Würthner, Frank and Bauerle, Peter and Sharma, Ganesh D.}, journal = {J. Mater. Chem. A}, keywords = {myown}, number = 28, pages = {14887-14897}, publisher = {The Royal Society of Chemistry}, title = {Unprecedented low energy losses in organic solar cells with high external quantum efficiencies by employing non-fullerene electron acceptors}, volume = 5, year = 2017 }

  %0 Journal Article %1 C7TA04703G %A Mishra, Amaresh %A Keshtov, Mukhamed[space]L. %A Looser, Annika %A Singhal, Rahul %A Stolte, Matthias %A Würthner, Frank %A Bauerle, Peter %A Sharma, Ganesh D. %D 2017 %I The Royal Society of Chemistry %J J. Mater. Chem. A %N 28 %P 14887-14897 %R 10.1039/C7TA04703G %T Unprecedented low energy losses in organic solar cells with high external quantum efficiencies by employing non-fullerene electron acceptors %U http://dx.doi.org/10.1039/C7TA04703G %V 5 %X In order to realize high photocurrent generation in the low-energy region of the solar spectrum, two conjugated A-D-A oligomers, PY-1 and DCI-2 comprising a central dithieno[3,2-b:2[prime or minute],3[prime or minute]-d]pyrrole donor (D) unit and end-capping acceptors (A) 1-butyl-4-methyl-2,6-dioxopyridine-3-carbonitrile (PY) or 3-dicyanomethyleneindan-1-one (DCI) have been synthesized and characterized. The oligomers showed strong absorptions in the red and near-IR region in solution and in the solid state. As a consequence of the strong electron-accepting character, the absorption band of DCI-2 in thin films is significantly red-shifted compared to that of PY-1 resulting in a low optical energy gap of 1.23 eV. In optimized solution-processed bulk-heterojunction solar cells using a polymeric donor P1, the new non-fullerene acceptor DCI-2 provides an excellent power conversion efficiency of 6.94% which is noticeably higher than that of PY-1-based devices (PCE = 4.89%). Most importantly, a high open-circuit voltage (VOC) of [similar]0.8 V with unprecedented energy losses, between the optical energy gap and the open-circuit voltage, between 0.39 and 0.43 eV concomitant with excellent external quantum efficiencies of 69%@880 nm in the NIR-regime have been achieved for DCI-2-based devices.
• Three-dimensional photonic confinement in imprinted liquid crystalline pillar microcavities. Dusel, Marco; Betzold, Simon; Brodbeck, Sebastian; Herbst, Stefanie; Würthner, Frank; Friedrich, Daniel; Hecht, Bert; Höfling, Sven; Dietrich, Christof P. In Applied Physics Letters, 110(20), p. 201113. 2017.
  • [ Abstract ]
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  We demonstrate the feasibility of a thermal imprint technology capable of structuring organic thin films with liquid crystalline properties forming feature sizes on a several micrometer scale. The imprint technique can directly be applied onto a variety of substrates including dielectric mirrors. The so fabricated three-dimensional microcavities have lateral extensions up to 20 μm and heights between 1 and 5 μm. Exemplarily, pillar microcavities were produced wherein three-dimensional photonic confinement is observed by the formation of 0D cavity mode patterns. The imprint technique further favors the formation of hemispherical pillar geometries rather than cylindrical pillars, resulting in equidistant mode spacings of transversal cavity modes.

  @article{doi:10.1063/1.4983565, abstract = {We demonstrate the feasibility of a thermal imprint technology capable of structuring organic thin films with liquid crystalline properties forming feature sizes on a several micrometer scale. The imprint technique can directly be applied onto a variety of substrates including dielectric mirrors. The so fabricated three-dimensional microcavities have lateral extensions up to 20 μm and heights between 1 and 5 μm. Exemplarily, pillar microcavities were produced wherein three-dimensional photonic confinement is observed by the formation of 0D cavity mode patterns. The imprint technique further favors the formation of hemispherical pillar geometries rather than cylindrical pillars, resulting in equidistant mode spacings of transversal cavity modes.}, author = {Dusel, Marco and Betzold, Simon and Brodbeck, Sebastian and Herbst, Stefanie and Würthner, Frank and Friedrich, Daniel and Hecht, Bert and Höfling, Sven and Dietrich, Christof P.}, journal = {Applied Physics Letters}, keywords = {myown}, number = 20, pages = 201113, title = {Three-dimensional photonic confinement in imprinted liquid crystalline pillar microcavities}, volume = 110, year = 2017 }

  %0 Journal Article %1 doi:10.1063/1.4983565 %A Dusel, Marco %A Betzold, Simon %A Brodbeck, Sebastian %A Herbst, Stefanie %A Würthner, Frank %A Friedrich, Daniel %A Hecht, Bert %A Höfling, Sven %A Dietrich, Christof P. %D 2017 %J Applied Physics Letters %N 20 %P 201113 %R 10.1063/1.4983565 %T Three-dimensional photonic confinement in imprinted liquid crystalline pillar microcavities %U https://doi.org/10.1063/1.4983565 %V 110 %X We demonstrate the feasibility of a thermal imprint technology capable of structuring organic thin films with liquid crystalline properties forming feature sizes on a several micrometer scale. The imprint technique can directly be applied onto a variety of substrates including dielectric mirrors. The so fabricated three-dimensional microcavities have lateral extensions up to 20 μm and heights between 1 and 5 μm. Exemplarily, pillar microcavities were produced wherein three-dimensional photonic confinement is observed by the formation of 0D cavity mode patterns. The imprint technique further favors the formation of hemispherical pillar geometries rather than cylindrical pillars, resulting in equidistant mode spacings of transversal cavity modes.
• Influence of optical material properties on strong coupling in organic semiconductor based microcavities. Tropf, Laura; Dietrich, Christof P.; Herbst, Stefanie; Kanibolotsky, Alexander L.; Skabara, Peter J.; Würthner, Frank; Samuel, Ifor D. W.; Gather, Malte C.; Höfling, Sven. In Applied Physics Letters, 110(15), p. 153302. 2017.
  • [ Abstract ]
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  The optical properties of organic semiconductors are generally characterised by a number of material specific parameters, including absorbance, photoluminescence quantum yield, Stokes shift, and molecular orientation. Here, we study four different organic semiconductors and compare their optical properties to the characteristics of the exciton-polaritons that are formed when these materials are introduced into metal-clad microcavities. We find that the strength of coupling between cavity photons and excitons is clearly correlated with the absorptivity of the material. In addition, we show that anisotropy strongly affects the characteristics of the formed exciton-polaritons.

  @article{doi:10.1063/1.4978646, abstract = {The optical properties of organic semiconductors are generally characterised by a number of material specific parameters, including absorbance, photoluminescence quantum yield, Stokes shift, and molecular orientation. Here, we study four different organic semiconductors and compare their optical properties to the characteristics of the exciton-polaritons that are formed when these materials are introduced into metal-clad microcavities. We find that the strength of coupling between cavity photons and excitons is clearly correlated with the absorptivity of the material. In addition, we show that anisotropy strongly affects the characteristics of the formed exciton-polaritons.}, author = {Tropf, Laura and Dietrich, Christof P. and Herbst, Stefanie and Kanibolotsky, Alexander L. and Skabara, Peter J. and Würthner, Frank and Samuel, Ifor D. W. and Gather, Malte C. and Höfling, Sven}, journal = {Applied Physics Letters}, keywords = {myown}, number = 15, pages = 153302, title = {Influence of optical material properties on strong coupling in organic semiconductor based microcavities}, volume = 110, year = 2017 }

  %0 Journal Article %1 doi:10.1063/1.4978646 %A Tropf, Laura %A Dietrich, Christof P. %A Herbst, Stefanie %A Kanibolotsky, Alexander L. %A Skabara, Peter J. %A Würthner, Frank %A Samuel, Ifor D. W. %A Gather, Malte C. %A Höfling, Sven %D 2017 %J Applied Physics Letters %N 15 %P 153302 %R 10.1063/1.4978646 %T Influence of optical material properties on strong coupling in organic semiconductor based microcavities %U https://doi.org/10.1063/1.4978646 %V 110 %X The optical properties of organic semiconductors are generally characterised by a number of material specific parameters, including absorbance, photoluminescence quantum yield, Stokes shift, and molecular orientation. Here, we study four different organic semiconductors and compare their optical properties to the characteristics of the exciton-polaritons that are formed when these materials are introduced into metal-clad microcavities. We find that the strength of coupling between cavity photons and excitons is clearly correlated with the absorptivity of the material. In addition, we show that anisotropy strongly affects the characteristics of the formed exciton-polaritons.
• Structure–Property Relationships from Atomistic Multiscale Simulations of the Relevant Processes in Organic Solar Cells. I. Thermodynamic Aspects. Brückner, Charlotte; Würthner, Frank; Meerholz, Klaus; Engels, Bernd. In J. Phys. Chem. C., 121(1), pp. 4–25. 2017.
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  Interface structures of a variety of molecular p-type semiconductors in heterojunction with fullerene C60 were generated in molecular dynamic simulations. Using the dimer method (i.e., dimers were used as the quantum-mechanical system) along with a continuum solvation approach and macroscopic electric fields, energetic profiles of the interfaces of organic solar cells (OSCs) were calculated. Several important loss mechanisms, such as exciton trapping, charge trapping, and interfacial charge-transfer traps, were observed. Structure–property relationships were established. They reveal that apart from the molecular orientation and dipolarity, molecular size is an important parameter that influences potential loss mechanisms.

  @article{doi:10.1021/acs.jpcc.6b06755, abstract = {Interface structures of a variety of molecular p-type semiconductors in heterojunction with fullerene C60 were generated in molecular dynamic simulations. Using the dimer method (i.e., dimers were used as the quantum-mechanical system) along with a continuum solvation approach and macroscopic electric fields, energetic profiles of the interfaces of organic solar cells (OSCs) were calculated. Several important loss mechanisms, such as exciton trapping, charge trapping, and interfacial charge-transfer traps, were observed. Structure–property relationships were established. They reveal that apart from the molecular orientation and dipolarity, molecular size is an important parameter that influences potential loss mechanisms.}, author = {Brückner, Charlotte and Würthner, Frank and Meerholz, Klaus and Engels, Bernd}, journal = {J. Phys. Chem. C.}, keywords = {myown}, number = 1, pages = {4-25}, title = {Structure–Property Relationships from Atomistic Multiscale Simulations of the Relevant Processes in Organic Solar Cells. I. Thermodynamic Aspects}, volume = 121, year = 2017 }

  %0 Journal Article %1 doi:10.1021/acs.jpcc.6b06755 %A Brückner, Charlotte %A Würthner, Frank %A Meerholz, Klaus %A Engels, Bernd %D 2017 %J J. Phys. Chem. C. %N 1 %P 4-25 %R 10.1021/acs.jpcc.6b06755 %T Structure–Property Relationships from Atomistic Multiscale Simulations of the Relevant Processes in Organic Solar Cells. I. Thermodynamic Aspects %U http://dx.doi.org/10.1021/acs.jpcc.6b06755 %V 121 %X Interface structures of a variety of molecular p-type semiconductors in heterojunction with fullerene C60 were generated in molecular dynamic simulations. Using the dimer method (i.e., dimers were used as the quantum-mechanical system) along with a continuum solvation approach and macroscopic electric fields, energetic profiles of the interfaces of organic solar cells (OSCs) were calculated. Several important loss mechanisms, such as exciton trapping, charge trapping, and interfacial charge-transfer traps, were observed. Structure–property relationships were established. They reveal that apart from the molecular orientation and dipolarity, molecular size is an important parameter that influences potential loss mechanisms.
• Fluorescence Polarization Measurements to Probe Alignment of a Bithiophene Dye in One-Dimensional Channels of Self-Assembled Phenylethynylene Bis-Urea Macrocycle Crystals. Kittikhunnatham, Preecha; Som, Bozumeh; Rassolov, Vitaly; Stolte, Matthias; Würthner, Frank; Shimizu, Linda S.; Greytak, Andrew B. In J. Phys. Chem. C., 121(33), pp. 18102–18109. 2017.
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  This paper describes the use of polarized fluorescence microscopy to directly probe guest molecule orientation in bis-urea macrocycle crystals. These macrocycles assemble to afford one-dimensional (1D) microchannels ∼9 Å in diameter that have previously been shown to exhibit normal Fickian diffusion and induce selective reactivity among the confined guest molecules. In the present work, we take advantage of the quasi-1D morphology of fiber-like microcrystals with the extended dimension corresponding to the channel axis to measure excitation and emission polarization values for a bithiophene guest. Guest fluorescence is shown to be polarized along the fiber axis with emission polarization values up to 0.729, indicating a high degree of orientational order within the 1D channels. The observed behavior is consistent with calculated results for the guest orientation and electronic transition dipole moment. The results indicate the value of functional fluorescent probes as a measure of guest confinement in low-dimensional environments.

  @article{doi:10.1021/acs.jpcc.7b07136, abstract = {This paper describes the use of polarized fluorescence microscopy to directly probe guest molecule orientation in bis-urea macrocycle crystals. These macrocycles assemble to afford one-dimensional (1D) microchannels ∼9 Å in diameter that have previously been shown to exhibit normal Fickian diffusion and induce selective reactivity among the confined guest molecules. In the present work, we take advantage of the quasi-1D morphology of fiber-like microcrystals with the extended dimension corresponding to the channel axis to measure excitation and emission polarization values for a bithiophene guest. Guest fluorescence is shown to be polarized along the fiber axis with emission polarization values up to 0.729, indicating a high degree of orientational order within the 1D channels. The observed behavior is consistent with calculated results for the guest orientation and electronic transition dipole moment. The results indicate the value of functional fluorescent probes as a measure of guest confinement in low-dimensional environments.}, author = {Kittikhunnatham, Preecha and Som, Bozumeh and Rassolov, Vitaly and Stolte, Matthias and Würthner, Frank and Shimizu, Linda S. and Greytak, Andrew B.}, journal = {J. Phys. Chem. C.}, keywords = {myown}, number = 33, pages = {18102-18109}, title = {Fluorescence Polarization Measurements to Probe Alignment of a Bithiophene Dye in One-Dimensional Channels of Self-Assembled Phenylethynylene Bis-Urea Macrocycle Crystals}, volume = 121, year = 2017 }

  %0 Journal Article %1 doi:10.1021/acs.jpcc.7b07136 %A Kittikhunnatham, Preecha %A Som, Bozumeh %A Rassolov, Vitaly %A Stolte, Matthias %A Würthner, Frank %A Shimizu, Linda S. %A Greytak, Andrew B. %D 2017 %J J. Phys. Chem. C. %N 33 %P 18102-18109 %R 10.1021/acs.jpcc.7b07136 %T Fluorescence Polarization Measurements to Probe Alignment of a Bithiophene Dye in One-Dimensional Channels of Self-Assembled Phenylethynylene Bis-Urea Macrocycle Crystals %U http://dx.doi.org/10.1021/acs.jpcc.7b07136 %V 121 %X This paper describes the use of polarized fluorescence microscopy to directly probe guest molecule orientation in bis-urea macrocycle crystals. These macrocycles assemble to afford one-dimensional (1D) microchannels ∼9 Å in diameter that have previously been shown to exhibit normal Fickian diffusion and induce selective reactivity among the confined guest molecules. In the present work, we take advantage of the quasi-1D morphology of fiber-like microcrystals with the extended dimension corresponding to the channel axis to measure excitation and emission polarization values for a bithiophene guest. Guest fluorescence is shown to be polarized along the fiber axis with emission polarization values up to 0.729, indicating a high degree of orientational order within the 1D channels. The observed behavior is consistent with calculated results for the guest orientation and electronic transition dipole moment. The results indicate the value of functional fluorescent probes as a measure of guest confinement in low-dimensional environments.
• Photo- and redoxfunctional cyclophanes, macrocycles, and catenanes based on aromatic bisimides. Spenst, Peter; Würthner, Frank. In Journal of Photochemistry and Photobiology C: Photochemistry Reviews, 31(Supplement C), pp. 114–138. 2017.
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  Abstract Aromatic bis(dicarboximides), abbreviated as bisimides or diimides, are interesting building blocks for the construction of electro- and photofunctional architectures. The possibility of reversible reduction of aromatic molecules equipped with imide units at modest redox potentials between about −1.3 and −1.0V vs. the ferrocenium/ferrocene redox couple could be exploited by a broad variety of electroactive cyclophanes, macrocycles and catenane scaffolds to direct molecular motions by charging the systems with electrons. Whilst most of the work in this field has been accomplished for the smaller pyromellitic (PyBI) and naphthalene bisimides (NBI), the larger perylene bisimides (PBI) offered an entry into the field of photofunctional systems. Here cyclophanes with closely stacked PBI units provided insight into exciton coupling in homo and hetero dye dimers or ultrafast loss of coherence of the initially populated exciton states to give excimers or symmetry-broken charge separated states. In contrast, for PBI cyclophanes with larger cavities guest encapsulation could efficiently modulate the photophysical properties to give highly fluorescent host–guest complexes upon incorporation of electron-poor aromatic guest molecules or fully quenched systems upon incorporation of electron-rich molecules. For larger PBI macrocycles energy transfer processes could be investigated as well as the solvent-templated folding into double string ropes with high sensitivity (absorption, fluorescence) for the specific aromatic solvents. Finally, with a metallosupramolecular approach larger macrocycles (e.g. squares and hexagons) and cages (e.g. tetrahedrons) became accessible which could be exploited to study a variety of electro- and photophysical processes.

  @article{SPENST2017114, abstract = {Abstract Aromatic bis(dicarboximides), abbreviated as bisimides or diimides, are interesting building blocks for the construction of electro- and photofunctional architectures. The possibility of reversible reduction of aromatic molecules equipped with imide units at modest redox potentials between about −1.3 and −1.0V vs. the ferrocenium/ferrocene redox couple could be exploited by a broad variety of electroactive cyclophanes, macrocycles and catenane scaffolds to direct molecular motions by charging the systems with electrons. Whilst most of the work in this field has been accomplished for the smaller pyromellitic (PyBI) and naphthalene bisimides (NBI), the larger perylene bisimides (PBI) offered an entry into the field of photofunctional systems. Here cyclophanes with closely stacked PBI units provided insight into exciton coupling in homo and hetero dye dimers or ultrafast loss of coherence of the initially populated exciton states to give excimers or symmetry-broken charge separated states. In contrast, for PBI cyclophanes with larger cavities guest encapsulation could efficiently modulate the photophysical properties to give highly fluorescent host–guest complexes upon incorporation of electron-poor aromatic guest molecules or fully quenched systems upon incorporation of electron-rich molecules. For larger PBI macrocycles energy transfer processes could be investigated as well as the solvent-templated folding into double string ropes with high sensitivity (absorption, fluorescence) for the specific aromatic solvents. Finally, with a metallosupramolecular approach larger macrocycles (e.g. squares and hexagons) and cages (e.g. tetrahedrons) became accessible which could be exploited to study a variety of electro- and photophysical processes.}, author = {Spenst, Peter and Würthner, Frank}, journal = {Journal of Photochemistry and Photobiology C: Photochemistry Reviews}, keywords = {properties}, number = {Supplement C}, pages = {114 - 138}, title = {Photo- and redoxfunctional cyclophanes, macrocycles, and catenanes based on aromatic bisimides}, volume = 31, year = 2017 }

  %0 Journal Article %1 SPENST2017114 %A Spenst, Peter %A Würthner, Frank %D 2017 %J Journal of Photochemistry and Photobiology C: Photochemistry Reviews %N Supplement C %P 114 - 138 %R https://doi.org/10.1016/j.jphotochemrev.2017.03.002 %T Photo- and redoxfunctional cyclophanes, macrocycles, and catenanes based on aromatic bisimides %U http://www.sciencedirect.com/science/article/pii/S1389556716300855 %V 31 %X Abstract Aromatic bis(dicarboximides), abbreviated as bisimides or diimides, are interesting building blocks for the construction of electro- and photofunctional architectures. The possibility of reversible reduction of aromatic molecules equipped with imide units at modest redox potentials between about −1.3 and −1.0V vs. the ferrocenium/ferrocene redox couple could be exploited by a broad variety of electroactive cyclophanes, macrocycles and catenane scaffolds to direct molecular motions by charging the systems with electrons. Whilst most of the work in this field has been accomplished for the smaller pyromellitic (PyBI) and naphthalene bisimides (NBI), the larger perylene bisimides (PBI) offered an entry into the field of photofunctional systems. Here cyclophanes with closely stacked PBI units provided insight into exciton coupling in homo and hetero dye dimers or ultrafast loss of coherence of the initially populated exciton states to give excimers or symmetry-broken charge separated states. In contrast, for PBI cyclophanes with larger cavities guest encapsulation could efficiently modulate the photophysical properties to give highly fluorescent host–guest complexes upon incorporation of electron-poor aromatic guest molecules or fully quenched systems upon incorporation of electron-rich molecules. For larger PBI macrocycles energy transfer processes could be investigated as well as the solvent-templated folding into double string ropes with high sensitivity (absorption, fluorescence) for the specific aromatic solvents. Finally, with a metallosupramolecular approach larger macrocycles (e.g. squares and hexagons) and cages (e.g. tetrahedrons) became accessible which could be exploited to study a variety of electro- and photophysical processes.
• Living Supramolecular Polymerization of a Perylene Bisimide Dye into Fluorescent J-Aggregates. Wagner, Wolfgang; Wehner, Marius; Stepanenko, Vladimir; Ogi, Soichiro; Würthner, Frank. In Angew. Chem. Int. Ed., (56), A. C. I. Ed. (ed.), pp. 16008–16012. 2017.
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  @article{noauthororeditor, author = {Wagner, Wolfgang and Wehner, Marius and Stepanenko, Vladimir and Ogi, Soichiro and Würthner, Frank}, editor = {Ed., Angewandte Chemie Int.}, journal = {Angew. Chem. Int. Ed.}, keywords = {organic}, month = 12, number = 56, pages = {16008-16012}, title = {Living Supramolecular Polymerization of a Perylene Bisimide Dye into Fluorescent J-Aggregates}, year = 2017 }

  %0 Journal Article %1 noauthororeditor %A Wagner, Wolfgang %A Wehner, Marius %A Stepanenko, Vladimir %A Ogi, Soichiro %A Würthner, Frank %D 2017 %E Ed., Angewandte Chemie Int. %J Angew. Chem. Int. Ed. %N 56 %P 16008-16012 %R DOI: 10.1002/anie.201709307 %T Living Supramolecular Polymerization of a Perylene Bisimide Dye into Fluorescent J-Aggregates
• Donor--Acceptor Dyes for Organic Photovoltaics. Arjona-Esteban, Alhama; Lenze, Martin Robert; Meerholz, Klaus; Würthner, Frank. In Elementary Processes in Organic Photovoltaics, K. Leo (ed.), pp. 193–214. 2017.
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  Small-molecule $\pi$-systems bearing donor (D) and acceptor (A) groups constitute an interesting class of dyes because of their tunable strong absorption, which covers the visible and near-infrared range. The dipolarity associated with D--A structures directs antiparallel stacking arrangements in the solid state, thus reducing the dipolar disorder at the supramolecular level. Their straightforward synthesis and purification make them good candidates for photovoltaic application with power conversion efficiencies >6\thinspace\%. This review summarizes the application of D--A dyes, and in particular merocyanines, in organic photovoltaics in recent years.

  @inbook{Arjona-Esteban2017, abstract = {Small-molecule $\pi$-systems bearing donor (D) and acceptor (A) groups constitute an interesting class of dyes because of their tunable strong absorption, which covers the visible and near-infrared range. The dipolarity associated with D–A structures directs antiparallel stacking arrangements in the solid state, thus reducing the dipolar disorder at the supramolecular level. Their straightforward synthesis and purification make them good candidates for photovoltaic application with power conversion efficiencies >6{\thinspace}{\%}. This review summarizes the application of D–A dyes, and in particular merocyanines, in organic photovoltaics in recent years.}, address = {Cham}, author = {Arjona-Esteban, Alhama and Lenze, Martin Robert and Meerholz, Klaus and Würthner, Frank}, booktitle = {Elementary Processes in Organic Photovoltaics}, editor = {Leo, Karl}, keywords = {myown}, pages = {193–214}, publisher = {Springer International Publishing}, title = {Donor–Acceptor Dyes for Organic Photovoltaics}, year = 2017 }

  %0 Book Section %1 Arjona-Esteban2017 %A Arjona-Esteban, Alhama %A Lenze, Martin Robert %A Meerholz, Klaus %A Würthner, Frank %B Elementary Processes in Organic Photovoltaics %C Cham %D 2017 %E Leo, Karl %I Springer International Publishing %P 193--214 %R 10.1007/978-3-319-28338-8_8 %T Donor--Acceptor Dyes for Organic Photovoltaics %U https://doi.org/10.1007/978-3-319-28338-8_8 %X Small-molecule $\pi$-systems bearing donor (D) and acceptor (A) groups constitute an interesting class of dyes because of their tunable strong absorption, which covers the visible and near-infrared range. The dipolarity associated with D--A structures directs antiparallel stacking arrangements in the solid state, thus reducing the dipolar disorder at the supramolecular level. Their straightforward synthesis and purification make them good candidates for photovoltaic application with power conversion efficiencies >6\thinspace\%. This review summarizes the application of D--A dyes, and in particular merocyanines, in organic photovoltaics in recent years. %@ 978-3-319-28338-8

• Tetramethoxy-bay-substituted perylene bisimides by copper-mediated cross-coupling. Leowanawat, Pawaret; Nowak-Krol, Agnieszka; Würthner, Frank. In Org. Chem. Front., 3(5), pp. 537–544. 2016.
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  CuBr-mediated cross-coupling of 1,6,7,12-tetrabromoperylene-3,4,9,10-tetracarboxylic acid ester or 1,6,7,12-tetrabromoperylene-3,4:9,10-bis(dicarboximide) with sodium methoxide affords the respective tetramethoxy-perylene dye derivatives which are excellent green ([small lambda]em [approximate] 555 nm) and red ([small lambda]em [approximate] 635 nm) emitters, respectively, with high fluorescence quantum yields (60-70%).

  @article{C6QO00047A, abstract = {CuBr-mediated cross-coupling of 1{,}6{,}7{,}12-tetrabromoperylene-3{,}4{,}9{,}10-tetracarboxylic acid ester or 1{,}6{,}7{,}12-tetrabromoperylene-3{,}4:9{,}10-bis(dicarboximide) with sodium methoxide affords the respective tetramethoxy-perylene dye derivatives which are excellent green ([small lambda]em [approximate] 555 nm) and red ([small lambda]em [approximate] 635 nm) emitters{,} respectively{,} with high fluorescence quantum yields (60-70%).}, author = {Leowanawat, Pawaret and Nowak-Krol, Agnieszka and Würthner, Frank}, journal = {Org. Chem. Front.}, keywords = {myown}, number = 5, pages = {537-544}, publisher = {The Royal Society of Chemistry}, title = {Tetramethoxy-bay-substituted perylene bisimides by copper-mediated cross-coupling}, volume = 3, year = 2016 }

  %0 Journal Article %1 C6QO00047A %A Leowanawat, Pawaret %A Nowak-Krol, Agnieszka %A Würthner, Frank %D 2016 %I The Royal Society of Chemistry %J Org. Chem. Front. %N 5 %P 537-544 %R 10.1039/C6QO00047A %T Tetramethoxy-bay-substituted perylene bisimides by copper-mediated cross-coupling %U http://dx.doi.org/10.1039/C6QO00047A %V 3 %X CuBr-mediated cross-coupling of 1,6,7,12-tetrabromoperylene-3,4,9,10-tetracarboxylic acid ester or 1,6,7,12-tetrabromoperylene-3,4:9,10-bis(dicarboximide) with sodium methoxide affords the respective tetramethoxy-perylene dye derivatives which are excellent green ([small lambda]em [approximate] 555 nm) and red ([small lambda]em [approximate] 635 nm) emitters, respectively, with high fluorescence quantum yields (60-70%).
• Anti-cooperative supramolecular polymerization: a new K2-K model applied to the self-assembly of perylene bisimide dye proceeding via well-defined hydrogen-bonded dimers. Gershberg, Jana; Fennel, Franziska; Rehm, Thomas H.; Lochbrunner, Stefan; Würthner, Frank. In Chem. Sci., 7(3), pp. 1729–1737. 2016.
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  A perylene bisimide dye bearing amide functionalities at the imide positions derived from amino acid l-alanine and a dialkoxy-substituted benzyl amine self-assembles into tightly bound dimers by [small pi]-[small pi]-stacking and hydrogen bonding in chloroform. In less polar or unpolar solvents like toluene and methylcyclohexane, and in their mixtures, these dimers further self-assemble into extended oligomeric aggregates in an anti-cooperative process in which even numbered aggregates are highly favoured. The stepwise transition from dimers into oligomers can not be properly described by conventional K2-K model, and thus a new K2-K aggregation model has been developed, which interpretes the present anti-cooperative supramolecular polymerization more appropriately. The newly developed K2-K model will be useful to describe self-assembly processes of a plethora of other [small pi]-conjugated molecules that are characterized by a favored dimer species.

  @article{C5SC03759J, abstract = {A perylene bisimide dye bearing amide functionalities at the imide positions derived from amino acid l-alanine and a dialkoxy-substituted benzyl amine self-assembles into tightly bound dimers by [small pi]-[small pi]-stacking and hydrogen bonding in chloroform. In less polar or unpolar solvents like toluene and methylcyclohexane{,} and in their mixtures{,} these dimers further self-assemble into extended oligomeric aggregates in an anti-cooperative process in which even numbered aggregates are highly favoured. The stepwise transition from dimers into oligomers can not be properly described by conventional K2-K model{,} and thus a new K2-K aggregation model has been developed{,} which interpretes the present anti-cooperative supramolecular polymerization more appropriately. The newly developed K2-K model will be useful to describe self-assembly processes of a plethora of other [small pi]-conjugated molecules that are characterized by a favored dimer species.}, author = {Gershberg, Jana and Fennel, Franziska and Rehm, Thomas H. and Lochbrunner, Stefan and Würthner, Frank}, journal = {Chem. Sci.}, keywords = {myown}, number = 3, pages = {1729-1737}, publisher = {The Royal Society of Chemistry}, title = {Anti-cooperative supramolecular polymerization: a new K2-K model applied to the self-assembly of perylene bisimide dye proceeding via well-defined hydrogen-bonded dimers}, volume = 7, year = 2016 }

  %0 Journal Article %1 C5SC03759J %A Gershberg, Jana %A Fennel, Franziska %A Rehm, Thomas H. %A Lochbrunner, Stefan %A Würthner, Frank %D 2016 %I The Royal Society of Chemistry %J Chem. Sci. %N 3 %P 1729-1737 %R 10.1039/C5SC03759J %T Anti-cooperative supramolecular polymerization: a new K2-K model applied to the self-assembly of perylene bisimide dye proceeding via well-defined hydrogen-bonded dimers %U http://dx.doi.org/10.1039/C5SC03759J %V 7 %X A perylene bisimide dye bearing amide functionalities at the imide positions derived from amino acid l-alanine and a dialkoxy-substituted benzyl amine self-assembles into tightly bound dimers by [small pi]-[small pi]-stacking and hydrogen bonding in chloroform. In less polar or unpolar solvents like toluene and methylcyclohexane, and in their mixtures, these dimers further self-assemble into extended oligomeric aggregates in an anti-cooperative process in which even numbered aggregates are highly favoured. The stepwise transition from dimers into oligomers can not be properly described by conventional K2-K model, and thus a new K2-K aggregation model has been developed, which interpretes the present anti-cooperative supramolecular polymerization more appropriately. The newly developed K2-K model will be useful to describe self-assembly processes of a plethora of other [small pi]-conjugated molecules that are characterized by a favored dimer species.
• Modulation of band gap and p- versus n-semiconductor character of ADA dyes by core and acceptor group variation. Nowak-Krol, Agnieszka; Wagener, Reinhard; Kraus, Felix; Mishra, Amaresh; Bauerle, Peter; Würthner, Frank. In Org. Chem. Front., 3(5), pp. 545–555. 2016.
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  A series of ADA dyes was synthesized by Knoevenagel condensation reactions between dialdehydes of the electron-rich dithienopyrrole (DTP), cyclopentadithiophene (CPDT), carbazole (CAR) and fluorene (FL) moieties and the electron-poor CH-acidic indandione (IND) or 1,1-dicyanomethylene-3-indanone (DCIND) units, respectively. The UV/vis absorption spectra of the dyes cover a wide range of the visible spectrum from 450 to almost 700 nm in solution. Likewise, owing to differently balanced donor and acceptor strengths they may be applicable either as p- or n-type organic semiconductor materials in transistor and solar cell devices. As a proof-of-concept for dye vacuum-deposited organic thin film transistors (OTFTs) with either hole or electron mobilities of [similar]0.1 cm2 V-1 s-1 depending on the HOMO/LUMO levels could be demonstrated.

  @article{C6QO00046K, abstract = {A series of ADA dyes was synthesized by Knoevenagel condensation reactions between dialdehydes of the electron-rich dithienopyrrole (DTP){,} cyclopentadithiophene (CPDT){,} carbazole (CAR) and fluorene (FL) moieties and the electron-poor CH-acidic indandione (IND) or 1{,}1-dicyanomethylene-3-indanone (DCIND) units{,} respectively. The UV/vis absorption spectra of the dyes cover a wide range of the visible spectrum from 450 to almost 700 nm in solution. Likewise{,} owing to differently balanced donor and acceptor strengths they may be applicable either as p- or n-type organic semiconductor materials in transistor and solar cell devices. As a proof-of-concept for dye vacuum-deposited organic thin film transistors (OTFTs) with either hole or electron mobilities of [similar]0.1 cm2 V-1 s-1 depending on the HOMO/LUMO levels could be demonstrated.}, author = {Nowak-Krol, Agnieszka and Wagener, Reinhard and Kraus, Felix and Mishra, Amaresh and Bauerle, Peter and Würthner, Frank}, journal = {Org. Chem. Front.}, keywords = {myown}, number = 5, pages = {545-555}, publisher = {The Royal Society of Chemistry}, title = {Modulation of band gap and p- versus n-semiconductor character of ADA dyes by core and acceptor group variation}, volume = 3, year = 2016 }

  %0 Journal Article %1 C6QO00046K %A Nowak-Krol, Agnieszka %A Wagener, Reinhard %A Kraus, Felix %A Mishra, Amaresh %A Bauerle, Peter %A Würthner, Frank %D 2016 %I The Royal Society of Chemistry %J Org. Chem. Front. %N 5 %P 545-555 %R 10.1039/C6QO00046K %T Modulation of band gap and p- versus n-semiconductor character of ADA dyes by core and acceptor group variation %U http://dx.doi.org/10.1039/C6QO00046K %V 3 %X A series of ADA dyes was synthesized by Knoevenagel condensation reactions between dialdehydes of the electron-rich dithienopyrrole (DTP), cyclopentadithiophene (CPDT), carbazole (CAR) and fluorene (FL) moieties and the electron-poor CH-acidic indandione (IND) or 1,1-dicyanomethylene-3-indanone (DCIND) units, respectively. The UV/vis absorption spectra of the dyes cover a wide range of the visible spectrum from 450 to almost 700 nm in solution. Likewise, owing to differently balanced donor and acceptor strengths they may be applicable either as p- or n-type organic semiconductor materials in transistor and solar cell devices. As a proof-of-concept for dye vacuum-deposited organic thin film transistors (OTFTs) with either hole or electron mobilities of [similar]0.1 cm2 V-1 s-1 depending on the HOMO/LUMO levels could be demonstrated.
• Anti-cooperative supramolecular polymerization: a new K2-K model applied to the self-assembly of perylene bisimide dye proceeding via well-defined hydrogen-bonded dimers. Gershberg, Jana; Fennel, Franziska; Rehm, Thomas H.; Lochbrunner, Stefan; Würthner, Frank. In Chem. Sci., 7(3), pp. 1729–1737. 2016.
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  A perylene bisimide dye bearing amide functionalities at the imide positions derived from amino acid l-alanine and a dialkoxy-substituted benzyl amine self-assembles into tightly bound dimers by [small pi]-[small pi]-stacking and hydrogen bonding in chloroform. In less polar or unpolar solvents like toluene and methylcyclohexane, and in their mixtures, these dimers further self-assemble into extended oligomeric aggregates in an anti-cooperative process in which even numbered aggregates are highly favoured. The stepwise transition from dimers into oligomers can not be properly described by conventional K2-K model, and thus a new K2-K aggregation model has been developed, which interpretes the present anti-cooperative supramolecular polymerization more appropriately. The newly developed K2-K model will be useful to describe self-assembly processes of a plethora of other [small pi]-conjugated molecules that are characterized by a favored dimer species.

  @article{C5SC03759J, abstract = {A perylene bisimide dye bearing amide functionalities at the imide positions derived from amino acid l-alanine and a dialkoxy-substituted benzyl amine self-assembles into tightly bound dimers by [small pi]-[small pi]-stacking and hydrogen bonding in chloroform. In less polar or unpolar solvents like toluene and methylcyclohexane{,} and in their mixtures{,} these dimers further self-assemble into extended oligomeric aggregates in an anti-cooperative process in which even numbered aggregates are highly favoured. The stepwise transition from dimers into oligomers can not be properly described by conventional K2-K model{,} and thus a new K2-K aggregation model has been developed{,} which interpretes the present anti-cooperative supramolecular polymerization more appropriately. The newly developed K2-K model will be useful to describe self-assembly processes of a plethora of other [small pi]-conjugated molecules that are characterized by a favored dimer species.}, author = {Gershberg, Jana and Fennel, Franziska and Rehm, Thomas H. and Lochbrunner, Stefan and Würthner, Frank}, journal = {Chem. Sci.}, keywords = {myown}, number = 3, pages = {1729-1737}, publisher = {The Royal Society of Chemistry}, title = {Anti-cooperative supramolecular polymerization: a new K2-K model applied to the self-assembly of perylene bisimide dye proceeding via well-defined hydrogen-bonded dimers}, volume = 7, year = 2016 }

  %0 Journal Article %1 C5SC03759J %A Gershberg, Jana %A Fennel, Franziska %A Rehm, Thomas H. %A Lochbrunner, Stefan %A Würthner, Frank %D 2016 %I The Royal Society of Chemistry %J Chem. Sci. %N 3 %P 1729-1737 %R 10.1039/C5SC03759J %T Anti-cooperative supramolecular polymerization: a new K2-K model applied to the self-assembly of perylene bisimide dye proceeding via well-defined hydrogen-bonded dimers %U http://dx.doi.org/10.1039/C5SC03759J %V 7 %X A perylene bisimide dye bearing amide functionalities at the imide positions derived from amino acid l-alanine and a dialkoxy-substituted benzyl amine self-assembles into tightly bound dimers by [small pi]-[small pi]-stacking and hydrogen bonding in chloroform. In less polar or unpolar solvents like toluene and methylcyclohexane, and in their mixtures, these dimers further self-assemble into extended oligomeric aggregates in an anti-cooperative process in which even numbered aggregates are highly favoured. The stepwise transition from dimers into oligomers can not be properly described by conventional K2-K model, and thus a new K2-K aggregation model has been developed, which interpretes the present anti-cooperative supramolecular polymerization more appropriately. The newly developed K2-K model will be useful to describe self-assembly processes of a plethora of other [small pi]-conjugated molecules that are characterized by a favored dimer species.
• Folding-induced exciton coupling in homo- and heterodimers of merocyanine dyes. Bialas, David; Kirchner, Eva; Würthner, Frank. In Chem. Commun., 52(19), pp. 3777–3780. 2016.
  • [ Abstract ]
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  Two identical or different merocyanine dyes were tethered by a rigid diphenylacetylene spacer unit that enables the folding of the two dyes into co-facially [small pi]-stacked structures in solvents of low polarity. Whilst the solvent-dependent absorption spectra of homodimers of identical dyes are easily interpreted as H-aggregates by exciton theory, the spectra of the heterodimers constitute a novel and more interesting case.

  @article{C6CC00221H, abstract = {Two identical or different merocyanine dyes were tethered by a rigid diphenylacetylene spacer unit that enables the folding of the two dyes into co-facially [small pi]-stacked structures in solvents of low polarity. Whilst the solvent-dependent absorption spectra of homodimers of identical dyes are easily interpreted as H-aggregates by exciton theory{,} the spectra of the heterodimers constitute a novel and more interesting case.}, author = {Bialas, David and Kirchner, Eva and Würthner, Frank}, journal = {Chem. Commun.}, keywords = {myown}, number = 19, pages = {3777-3780}, publisher = {The Royal Society of Chemistry}, title = {Folding-induced exciton coupling in homo- and heterodimers of merocyanine dyes}, volume = 52, year = 2016 }

  %0 Journal Article %1 C6CC00221H %A Bialas, David %A Kirchner, Eva %A Würthner, Frank %D 2016 %I The Royal Society of Chemistry %J Chem. Commun. %N 19 %P 3777-3780 %R 10.1039/C6CC00221H %T Folding-induced exciton coupling in homo- and heterodimers of merocyanine dyes %U http://dx.doi.org/10.1039/C6CC00221H %V 52 %X Two identical or different merocyanine dyes were tethered by a rigid diphenylacetylene spacer unit that enables the folding of the two dyes into co-facially [small pi]-stacked structures in solvents of low polarity. Whilst the solvent-dependent absorption spectra of homodimers of identical dyes are easily interpreted as H-aggregates by exciton theory, the spectra of the heterodimers constitute a novel and more interesting case.
• Organic Semiconductors based on Dyes and Color Pigments. Gsänger, Marcel; Bialas, David; Huang, Lizhen; Stolte, Matthias; Würthner, Frank. In Advanced Materials, 28(19), pp. 3615–3645. 2016.
  • [ Abstract ]
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  Organic dyes and pigments constitute a large class of industrial products. The utilization of these compounds in the field of organic electronics is reviewed with particular emphasis on organic field-effect transistors. It is shown that for most major classes of industrial dyes and pigments, i.e., phthalocyanines, perylene and naphthalene diimides, diketopyrrolopyrroles, indigos and isoindigos, squaraines, and merocyanines, charge-carrier mobilities exceeding 1 cm2 V−1 s−1 have been achieved. The most widely investigated molecules due to their n-channel operation are perylene and naphthalene diimides, for which even values close to 10 cm2 V−1 s−1 have been demonstrated. The fact that all of these π-conjugated colorants contain polar substituents leading to strongly quadrupolar or even dipolar molecules suggests that indeed a much larger structural space shows promise for the design of organic semiconductor molecules than was considered in this field traditionally. In particular, because many of these dye and pigment chromophores demonstrate excellent thermal and (photo-)chemical stability in their original applications in dyeing and printing, and are accessible by straightforward synthetic protocols, they bear a particularly high potential for commercial applications in the area of organic electronics.

  @article{ADMA:ADMA201505440, abstract = {Organic dyes and pigments constitute a large class of industrial products. The utilization of these compounds in the field of organic electronics is reviewed with particular emphasis on organic field-effect transistors. It is shown that for most major classes of industrial dyes and pigments, i.e., phthalocyanines, perylene and naphthalene diimides, diketopyrrolopyrroles, indigos and isoindigos, squaraines, and merocyanines, charge-carrier mobilities exceeding 1 cm2 V−1 s−1 have been achieved. The most widely investigated molecules due to their n-channel operation are perylene and naphthalene diimides, for which even values close to 10 cm2 V−1 s−1 have been demonstrated. The fact that all of these π-conjugated colorants contain polar substituents leading to strongly quadrupolar or even dipolar molecules suggests that indeed a much larger structural space shows promise for the design of organic semiconductor molecules than was considered in this field traditionally. In particular, because many of these dye and pigment chromophores demonstrate excellent thermal and (photo-)chemical stability in their original applications in dyeing and printing, and are accessible by straightforward synthetic protocols, they bear a particularly high potential for commercial applications in the area of organic electronics.}, author = {Gsänger, Marcel and Bialas, David and Huang, Lizhen and Stolte, Matthias and Würthner, Frank}, journal = {Advanced Materials}, keywords = {myown}, number = 19, pages = {3615–3645}, title = {Organic Semiconductors based on Dyes and Color Pigments}, volume = 28, year = 2016 }

  %0 Journal Article %1 ADMA:ADMA201505440 %A Gsänger, Marcel %A Bialas, David %A Huang, Lizhen %A Stolte, Matthias %A Würthner, Frank %D 2016 %J Advanced Materials %N 19 %P 3615--3645 %R 10.1002/adma.201505440 %T Organic Semiconductors based on Dyes and Color Pigments %U http://dx.doi.org/10.1002/adma.201505440 %V 28 %X Organic dyes and pigments constitute a large class of industrial products. The utilization of these compounds in the field of organic electronics is reviewed with particular emphasis on organic field-effect transistors. It is shown that for most major classes of industrial dyes and pigments, i.e., phthalocyanines, perylene and naphthalene diimides, diketopyrrolopyrroles, indigos and isoindigos, squaraines, and merocyanines, charge-carrier mobilities exceeding 1 cm2 V−1 s−1 have been achieved. The most widely investigated molecules due to their n-channel operation are perylene and naphthalene diimides, for which even values close to 10 cm2 V−1 s−1 have been demonstrated. The fact that all of these π-conjugated colorants contain polar substituents leading to strongly quadrupolar or even dipolar molecules suggests that indeed a much larger structural space shows promise for the design of organic semiconductor molecules than was considered in this field traditionally. In particular, because many of these dye and pigment chromophores demonstrate excellent thermal and (photo-)chemical stability in their original applications in dyeing and printing, and are accessible by straightforward synthetic protocols, they bear a particularly high potential for commercial applications in the area of organic electronics.
• Liquid-Crystalline Squaraine Dyes with Anisotropic Absorption of Near Infrared Light. Soberats, Bartolome; Mayerhöffer, Ulrich; Würthner, Frank. In Advanced Optical Materials, 4(8), pp. 1186–1189. 2016.
  • [ Abstract ]
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  A novel squaraine dye constitutes an unusual nematic mesogen absorbing in the near infrared region. Aligned thin films of the squaraine material are produced by mechanical shearing of the liquid-crystalline phase and feature remarkable anisotropic absorption of linearly polarized light in the spectral region between 600 and 1000 nm.

  @article{ADOM:ADOM201600257, abstract = {A novel squaraine dye constitutes an unusual nematic mesogen absorbing in the near infrared region. Aligned thin films of the squaraine material are produced by mechanical shearing of the liquid-crystalline phase and feature remarkable anisotropic absorption of linearly polarized light in the spectral region between 600 and 1000 nm.}, author = {Soberats, Bartolome and Mayerhöffer, Ulrich and Würthner, Frank}, journal = {Advanced Optical Materials}, keywords = {myown}, number = 8, pages = {1186–1189}, title = {Liquid-Crystalline Squaraine Dyes with Anisotropic Absorption of Near Infrared Light}, volume = 4, year = 2016 }

  %0 Journal Article %1 ADOM:ADOM201600257 %A Soberats, Bartolome %A Mayerhöffer, Ulrich %A Würthner, Frank %D 2016 %J Advanced Optical Materials %N 8 %P 1186--1189 %R 10.1002/adom.201600257 %T Liquid-Crystalline Squaraine Dyes with Anisotropic Absorption of Near Infrared Light %U http://dx.doi.org/10.1002/adom.201600257 %V 4 %X A novel squaraine dye constitutes an unusual nematic mesogen absorbing in the near infrared region. Aligned thin films of the squaraine material are produced by mechanical shearing of the liquid-crystalline phase and feature remarkable anisotropic absorption of linearly polarized light in the spectral region between 600 and 1000 nm.
• Impact of Alkyl Spacer Length on Aggregation Pathways in Kinetically Controlled Supramolecular Polymerization. Ogi, Soichiro; Stepanenko, Vladimir; Thein, Johannes; Würthner, Frank. In J. Am. Chem. Soc., 138(2), pp. 670–678. 2016.

  PMID: 26699283
  • [ Abstract ]
  • [ BibTeX ]
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  We have investigated the kinetic and thermodynamic supramolecular polymerizations of a series of amide-functionalized perylene bisimide (PBI) organogelator molecules bearing alkyl spacers of varied lengths (ethylene to pentylene chains, PBI-1-C2 to PBI-1-C5) between the amide and PBI imide groups. These amide-functionalized PBIs form one-dimensional fibrous nanostructures as the thermodynamically favored states in solvents of low polarity. Our in-depth studies revealed, however, that the kinetic behavior of their supramolecular polymerization is dependent on the spacer length. Propylene- and pentylene-tethered PBIs follow a similar polymerization process as previously observed for the ethylene-tethered PBI. Thus, the monomers of these PBIs are kinetically trapped in conformationally restricted states through intramolecular hydrogen bonding between the amide and imide groups. In contrast, the intramolecularly hydrogen-bonded monomers of butylene-tethered PBI spontaneously self-assemble into nanoparticles, which constitute an off-pathway aggregate state with regard to the thermodynamically stable fibrous supramolecular polymers obtained. Thus, for this class of π-conjugated system, an unprecedented off-pathway aggregate with high kinetic stability could be realized for the first time by introducing an alkyl linker of optimum length (C4 chain) between the amide and imide groups. Our current system with an energy landscape of two competing nucleated aggregation pathways is applicable to the kinetic control over the supramolecular polymerization by the seeding approach.

  @article{doi:10.1021/jacs.5b11674, abstract = {We have investigated the kinetic and thermodynamic supramolecular polymerizations of a series of amide-functionalized perylene bisimide (PBI) organogelator molecules bearing alkyl spacers of varied lengths (ethylene to pentylene chains, PBI-1-C2 to PBI-1-C5) between the amide and PBI imide groups. These amide-functionalized PBIs form one-dimensional fibrous nanostructures as the thermodynamically favored states in solvents of low polarity. Our in-depth studies revealed, however, that the kinetic behavior of their supramolecular polymerization is dependent on the spacer length. Propylene- and pentylene-tethered PBIs follow a similar polymerization process as previously observed for the ethylene-tethered PBI. Thus, the monomers of these PBIs are kinetically trapped in conformationally restricted states through intramolecular hydrogen bonding between the amide and imide groups. In contrast, the intramolecularly hydrogen-bonded monomers of butylene-tethered PBI spontaneously self-assemble into nanoparticles, which constitute an off-pathway aggregate state with regard to the thermodynamically stable fibrous supramolecular polymers obtained. Thus, for this class of π-conjugated system, an unprecedented off-pathway aggregate with high kinetic stability could be realized for the first time by introducing an alkyl linker of optimum length (C4 chain) between the amide and imide groups. Our current system with an energy landscape of two competing nucleated aggregation pathways is applicable to the kinetic control over the supramolecular polymerization by the seeding approach.}, author = {Ogi, Soichiro and Stepanenko, Vladimir and Thein, Johannes and Würthner, Frank}, journal = {J. Am. Chem. Soc.}, keywords = {myown}, note = {PMID: 26699283}, number = 2, pages = {670-678}, title = {Impact of Alkyl Spacer Length on Aggregation Pathways in Kinetically Controlled Supramolecular Polymerization}, volume = 138, year = 2016 }

  %0 Journal Article %1 doi:10.1021/jacs.5b11674 %A Ogi, Soichiro %A Stepanenko, Vladimir %A Thein, Johannes %A Würthner, Frank %D 2016 %J J. Am. Chem. Soc. %N 2 %P 670-678 %R 10.1021/jacs.5b11674 %T Impact of Alkyl Spacer Length on Aggregation Pathways in Kinetically Controlled Supramolecular Polymerization %U /brokenurl# http://dx.doi.org/10.1021/jacs.5b11674 %V 138 %X We have investigated the kinetic and thermodynamic supramolecular polymerizations of a series of amide-functionalized perylene bisimide (PBI) organogelator molecules bearing alkyl spacers of varied lengths (ethylene to pentylene chains, PBI-1-C2 to PBI-1-C5) between the amide and PBI imide groups. These amide-functionalized PBIs form one-dimensional fibrous nanostructures as the thermodynamically favored states in solvents of low polarity. Our in-depth studies revealed, however, that the kinetic behavior of their supramolecular polymerization is dependent on the spacer length. Propylene- and pentylene-tethered PBIs follow a similar polymerization process as previously observed for the ethylene-tethered PBI. Thus, the monomers of these PBIs are kinetically trapped in conformationally restricted states through intramolecular hydrogen bonding between the amide and imide groups. In contrast, the intramolecularly hydrogen-bonded monomers of butylene-tethered PBI spontaneously self-assemble into nanoparticles, which constitute an off-pathway aggregate state with regard to the thermodynamically stable fibrous supramolecular polymers obtained. Thus, for this class of π-conjugated system, an unprecedented off-pathway aggregate with high kinetic stability could be realized for the first time by introducing an alkyl linker of optimum length (C4 chain) between the amide and imide groups. Our current system with an energy landscape of two competing nucleated aggregation pathways is applicable to the kinetic control over the supramolecular polymerization by the seeding approach.
• Aqueous Solution Processed Photoconductive Cathode Interlayer for High Performance Polymer Solar Cells with Thick Interlayer and Thick Active Layer. Nian, Li; Chen, Zhenhui; Herbst, Stefanie; Li, Qingyuan; Yu, Chengzhuo; Jiang, Xiaofang; Dong, Huanli; Li, Fenghong; Liu, Linlin; Würthner, Frank; Chen, Junwu; Xie, Zengqi; Ma, Yuguang. In Advanced Materials, 28(34), pp. 7521–7526. 2016.
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  @article{ADMA:ADMA201601615, author = {Nian, Li and Chen, Zhenhui and Herbst, Stefanie and Li, Qingyuan and Yu, Chengzhuo and Jiang, Xiaofang and Dong, Huanli and Li, Fenghong and Liu, Linlin and Würthner, Frank and Chen, Junwu and Xie, Zengqi and Ma, Yuguang}, journal = {Advanced Materials}, keywords = {myown}, number = 34, pages = {7521–7526}, title = {Aqueous Solution Processed Photoconductive Cathode Interlayer for High Performance Polymer Solar Cells with Thick Interlayer and Thick Active Layer}, volume = 28, year = 2016 }

  %0 Journal Article %1 ADMA:ADMA201601615 %A Nian, Li %A Chen, Zhenhui %A Herbst, Stefanie %A Li, Qingyuan %A Yu, Chengzhuo %A Jiang, Xiaofang %A Dong, Huanli %A Li, Fenghong %A Liu, Linlin %A Würthner, Frank %A Chen, Junwu %A Xie, Zengqi %A Ma, Yuguang %D 2016 %J Advanced Materials %N 34 %P 7521--7526 %R 10.1002/adma.201601615 %T Aqueous Solution Processed Photoconductive Cathode Interlayer for High Performance Polymer Solar Cells with Thick Interlayer and Thick Active Layer %U http://dx.doi.org/10.1002/adma.201601615 %V 28
• Perylene Bisimide Dye Assemblies as Archetype Functional Supramolecular Materials. Würthner, Frank; Saha-Möller, Chantu R.; Fimmel, Benjamin; Ogi, Soichiro; Leowanawat, Pawaret; Schmidt, David. In Chemical Reviews, 116(3), pp. 962–1052. 2016.

  PMID: 26270260
  • [ Abstract ]
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  When many of the currently largest chemical companies were founded about 150 years ago, textile dyes constituted their first products. Interestingly, while most of the utilized colorants colored the textiles as monomeric dyes, others such as indigo were of nanocrystalline character.(1) For the latter, the coloristic properties are accordingly influenced strongly by dye–dye interactions as in organic pigment colorants.(2) This division of colorants into two classes, dyes and pigments, prevails today also in all kinds of functional dye-based materials, which are based on either single dye molecules, for example, fluorescent labels,(3) or bulk materials, for example, organic semiconductors.(4) Because of the increasing importance of the latter for many high technology applications, there is a growing interest in understanding dye–dye interactions and how these interactions impact the properties of nano- or bulk solid-state materials such as absorption, solid-state fluorescence, exciton, and hole and electron transport, to mention just a few. Such understanding can be derived from investigations on supramolecular dye assemblies(5) that constitute the intermediate state of matter between monomeric dyes and solid-state materials.

  @article{doi:10.1021/acs.chemrev.5b00188, abstract = {When many of the currently largest chemical companies were founded about 150 years ago, textile dyes constituted their first products. Interestingly, while most of the utilized colorants colored the textiles as monomeric dyes, others such as indigo were of nanocrystalline character.(1) For the latter, the coloristic properties are accordingly influenced strongly by dye–dye interactions as in organic pigment colorants.(2) This division of colorants into two classes, dyes and pigments, prevails today also in all kinds of functional dye-based materials, which are based on either single dye molecules, for example, fluorescent labels,(3) or bulk materials, for example, organic semiconductors.(4) Because of the increasing importance of the latter for many high technology applications, there is a growing interest in understanding dye–dye interactions and how these interactions impact the properties of nano- or bulk solid-state materials such as absorption, solid-state fluorescence, exciton, and hole and electron transport, to mention just a few. Such understanding can be derived from investigations on supramolecular dye assemblies(5) that constitute the intermediate state of matter between monomeric dyes and solid-state materials.}, author = {Würthner, Frank and Saha-Möller, Chantu R. and Fimmel, Benjamin and Ogi, Soichiro and Leowanawat, Pawaret and Schmidt, David}, journal = {Chemical Reviews}, keywords = {myown}, note = {PMID: 26270260}, number = 3, pages = {962-1052}, title = {Perylene Bisimide Dye Assemblies as Archetype Functional Supramolecular Materials}, volume = 116, year = 2016 }

  %0 Journal Article %1 doi:10.1021/acs.chemrev.5b00188 %A Würthner, Frank %A Saha-Möller, Chantu R. %A Fimmel, Benjamin %A Ogi, Soichiro %A Leowanawat, Pawaret %A Schmidt, David %D 2016 %J Chemical Reviews %N 3 %P 962-1052 %R 10.1021/acs.chemrev.5b00188 %T Perylene Bisimide Dye Assemblies as Archetype Functional Supramolecular Materials %U http://dx.doi.org/10.1021/acs.chemrev.5b00188 %V 116 %X When many of the currently largest chemical companies were founded about 150 years ago, textile dyes constituted their first products. Interestingly, while most of the utilized colorants colored the textiles as monomeric dyes, others such as indigo were of nanocrystalline character.(1) For the latter, the coloristic properties are accordingly influenced strongly by dye–dye interactions as in organic pigment colorants.(2) This division of colorants into two classes, dyes and pigments, prevails today also in all kinds of functional dye-based materials, which are based on either single dye molecules, for example, fluorescent labels,(3) or bulk materials, for example, organic semiconductors.(4) Because of the increasing importance of the latter for many high technology applications, there is a growing interest in understanding dye–dye interactions and how these interactions impact the properties of nano- or bulk solid-state materials such as absorption, solid-state fluorescence, exciton, and hole and electron transport, to mention just a few. Such understanding can be derived from investigations on supramolecular dye assemblies(5) that constitute the intermediate state of matter between monomeric dyes and solid-state materials.
• Diketopyrrolopyrrole Organic Thin-Film Transistors: Impact of Alkyl Substituents and Tolerance of Ethylhexyl Stereoisomers. Stolte, Matthias; Suraru, Sabin-Lucian; Diemer, Patricia; He, Tao; Burschka, Christian; Zschieschang, Ute; Klauk, Hagen; Würthner, Frank. In Advanced Functional Materials, 26(41), pp. 7415–7422. 2016.
  • [ Abstract ]
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  Bis(thiophen-2-yl)-diketopyrrolopyrrole (DPP) dyes bearing various alkyl substituents at the amide positions (n-butyl, n-pentyl, n-hexyl, n-heptyl, n-octyl, 2-ethylhexyl) and chlorine (Cl), bromine (Br), or cyano (CN) substituents at the thiophene positions have been synthesized and investigated with regard to their molecular and semiconducting properties. Intense absorption, strong fluorescence, and reversible oxidation and reduction processes are common to all of these dyes. Their characterization as organic semiconductors in vacuum-processed thin-film transistors reveals p-channel operation with field-effect mobilities ranging from 0.01 to 0.7 cm2 V−1 s−1. The highest mobility is found for the DPP dyes bearing the 2-ethylhexyl substituents, which is surprising, considering that as a result of the chiral substituents, this material is a mixture of (R,R), (S,S), and (R,S) stereoisomers. The high carrier mobility in the films of the DPPs bearing stereoisomerically inhomogeneous ethylhexyl groups is rationalized here by single-crystal X-ray diffraction (XRD) analysis in combination with XRD and atomic force microscopy studies on thin films, which reveal the presence of slightly different 2D layer arrangements for the n-alkyl and the 2-ethylhexyl derivatives. For the cyano-substituted DPPs possessing the lowest LUMO levels, ambipolar transport characteristics are observed.

  @article{ADFM:ADFM201602994, abstract = {Bis(thiophen-2-yl)-diketopyrrolopyrrole (DPP) dyes bearing various alkyl substituents at the amide positions (n-butyl, n-pentyl, n-hexyl, n-heptyl, n-octyl, 2-ethylhexyl) and chlorine (Cl), bromine (Br), or cyano (CN) substituents at the thiophene positions have been synthesized and investigated with regard to their molecular and semiconducting properties. Intense absorption, strong fluorescence, and reversible oxidation and reduction processes are common to all of these dyes. Their characterization as organic semiconductors in vacuum-processed thin-film transistors reveals p-channel operation with field-effect mobilities ranging from 0.01 to 0.7 cm2 V−1 s−1. The highest mobility is found for the DPP dyes bearing the 2-ethylhexyl substituents, which is surprising, considering that as a result of the chiral substituents, this material is a mixture of (R,R), (S,S), and (R,S) stereoisomers. The high carrier mobility in the films of the DPPs bearing stereoisomerically inhomogeneous ethylhexyl groups is rationalized here by single-crystal X-ray diffraction (XRD) analysis in combination with XRD and atomic force microscopy studies on thin films, which reveal the presence of slightly different 2D layer arrangements for the n-alkyl and the 2-ethylhexyl derivatives. For the cyano-substituted DPPs possessing the lowest LUMO levels, ambipolar transport characteristics are observed.}, author = {Stolte, Matthias and Suraru, Sabin-Lucian and Diemer, Patricia and He, Tao and Burschka, Christian and Zschieschang, Ute and Klauk, Hagen and Würthner, Frank}, journal = {Advanced Functional Materials}, keywords = {myown}, number = 41, pages = {7415–7422}, title = {Diketopyrrolopyrrole Organic Thin-Film Transistors: Impact of Alkyl Substituents and Tolerance of Ethylhexyl Stereoisomers}, volume = 26, year = 2016 }

  %0 Journal Article %1 ADFM:ADFM201602994 %A Stolte, Matthias %A Suraru, Sabin-Lucian %A Diemer, Patricia %A He, Tao %A Burschka, Christian %A Zschieschang, Ute %A Klauk, Hagen %A Würthner, Frank %D 2016 %J Advanced Functional Materials %N 41 %P 7415--7422 %R 10.1002/adfm.201602994 %T Diketopyrrolopyrrole Organic Thin-Film Transistors: Impact of Alkyl Substituents and Tolerance of Ethylhexyl Stereoisomers %U http://dx.doi.org/10.1002/adfm.201602994 %V 26 %X Bis(thiophen-2-yl)-diketopyrrolopyrrole (DPP) dyes bearing various alkyl substituents at the amide positions (n-butyl, n-pentyl, n-hexyl, n-heptyl, n-octyl, 2-ethylhexyl) and chlorine (Cl), bromine (Br), or cyano (CN) substituents at the thiophene positions have been synthesized and investigated with regard to their molecular and semiconducting properties. Intense absorption, strong fluorescence, and reversible oxidation and reduction processes are common to all of these dyes. Their characterization as organic semiconductors in vacuum-processed thin-film transistors reveals p-channel operation with field-effect mobilities ranging from 0.01 to 0.7 cm2 V−1 s−1. The highest mobility is found for the DPP dyes bearing the 2-ethylhexyl substituents, which is surprising, considering that as a result of the chiral substituents, this material is a mixture of (R,R), (S,S), and (R,S) stereoisomers. The high carrier mobility in the films of the DPPs bearing stereoisomerically inhomogeneous ethylhexyl groups is rationalized here by single-crystal X-ray diffraction (XRD) analysis in combination with XRD and atomic force microscopy studies on thin films, which reveal the presence of slightly different 2D layer arrangements for the n-alkyl and the 2-ethylhexyl derivatives. For the cyano-substituted DPPs possessing the lowest LUMO levels, ambipolar transport characteristics are observed.
• Library of Azabenz-Annulated Core-Extended Perylene Derivatives with Diverse Substitution Patterns and Tunable Electronic and Optical Properties. Schulze, Marcus; Philipp, Michael; Waigel, Waldemar; Schmidt, David; Würthner, Frank. In The Journal of Organic Chemistry, 81(18), pp. 8394–8405. 2016.

  PMID: 27568658
  • [ Abstract ]
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  • [ DOI ]
  Here, we present a collection of different azabenz-annulated perylene derivatives. By developing new synthetic strategies and improving existing protocols, we have expanded the structural diversity of these dye molecules to a multifunctional class of ligating chromophores. The Pictet–Spengler (PS) reaction of 1-amino-perylenes with different aldehydes is used to modify the terminal substitution pattern. PS transformations of 1,6- and/or 1,7-diamino perylenes result in 2-fold annulated nitrogen-containing coronene-type molecules like anti-(ab)2-PBI 15, syn-(ab)2-PBI 16, and syn-(ab)2-PTE 18. In addition, azabenz-annulated perylene bisanhydrides (ab-PBA 6 and syn-(ab)2-PBA 19) were explored as universal starting materials providing access to any desired imide functionality. Furthermore, a newly developed regioselective nitration procedure for perylene monoimide diesters (PMIDE) enables the synthesis of 1-nitro-PMIDE 10 and thus of azabenz-annulated perylene derivatives with unsymmetric peri-substitution patterns (ab-PMIDE 12 and ab-PMIMA 13). According to our spectroscopic and theoretical investigations, the optical and electrochemical properties of these multifunctional chromophores can easily be modified and adjusted to many desirable applications following the synthetic strategies presented in this work.

  @article{doi:10.1021/acs.joc.6b01573, abstract = {Here, we present a collection of different azabenz-annulated perylene derivatives. By developing new synthetic strategies and improving existing protocols, we have expanded the structural diversity of these dye molecules to a multifunctional class of ligating chromophores. The Pictet–Spengler (PS) reaction of 1-amino-perylenes with different aldehydes is used to modify the terminal substitution pattern. PS transformations of 1,6- and/or 1,7-diamino perylenes result in 2-fold annulated nitrogen-containing coronene-type molecules like anti-(ab)2-PBI 15, syn-(ab)2-PBI 16, and syn-(ab)2-PTE 18. In addition, azabenz-annulated perylene bisanhydrides (ab-PBA 6 and syn-(ab)2-PBA 19) were explored as universal starting materials providing access to any desired imide functionality. Furthermore, a newly developed regioselective nitration procedure for perylene monoimide diesters (PMIDE) enables the synthesis of 1-nitro-PMIDE 10 and thus of azabenz-annulated perylene derivatives with unsymmetric peri-substitution patterns (ab-PMIDE 12 and ab-PMIMA 13). According to our spectroscopic and theoretical investigations, the optical and electrochemical properties of these multifunctional chromophores can easily be modified and adjusted to many desirable applications following the synthetic strategies presented in this work.}, author = {Schulze, Marcus and Philipp, Michael and Waigel, Waldemar and Schmidt, David and Würthner, Frank}, journal = {The Journal of Organic Chemistry}, keywords = {myown}, note = {PMID: 27568658}, number = 18, pages = {8394-8405}, title = {Library of Azabenz-Annulated Core-Extended Perylene Derivatives with Diverse Substitution Patterns and Tunable Electronic and Optical Properties}, volume = 81, year = 2016 }

  %0 Journal Article %1 doi:10.1021/acs.joc.6b01573 %A Schulze, Marcus %A Philipp, Michael %A Waigel, Waldemar %A Schmidt, David %A Würthner, Frank %D 2016 %J The Journal of Organic Chemistry %N 18 %P 8394-8405 %R 10.1021/acs.joc.6b01573 %T Library of Azabenz-Annulated Core-Extended Perylene Derivatives with Diverse Substitution Patterns and Tunable Electronic and Optical Properties %U /brokenurl# http://dx.doi.org/10.1021/acs.joc.6b01573 %V 81 %X Here, we present a collection of different azabenz-annulated perylene derivatives. By developing new synthetic strategies and improving existing protocols, we have expanded the structural diversity of these dye molecules to a multifunctional class of ligating chromophores. The Pictet–Spengler (PS) reaction of 1-amino-perylenes with different aldehydes is used to modify the terminal substitution pattern. PS transformations of 1,6- and/or 1,7-diamino perylenes result in 2-fold annulated nitrogen-containing coronene-type molecules like anti-(ab)2-PBI 15, syn-(ab)2-PBI 16, and syn-(ab)2-PTE 18. In addition, azabenz-annulated perylene bisanhydrides (ab-PBA 6 and syn-(ab)2-PBA 19) were explored as universal starting materials providing access to any desired imide functionality. Furthermore, a newly developed regioselective nitration procedure for perylene monoimide diesters (PMIDE) enables the synthesis of 1-nitro-PMIDE 10 and thus of azabenz-annulated perylene derivatives with unsymmetric peri-substitution patterns (ab-PMIDE 12 and ab-PMIMA 13). According to our spectroscopic and theoretical investigations, the optical and electrochemical properties of these multifunctional chromophores can easily be modified and adjusted to many desirable applications following the synthetic strategies presented in this work.
• A supramolecular ruthenium macrocycle with high catalytic activity for water oxidation that mechanistically mimics photosystem II. Schulze, Marcus; Kunz, Valentin; Frischmann, Peter D.; Würthner, Frank. In Nat Chem, 8(6), pp. 576–583. 2016.
  • [ Abstract ]
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  Mimicking the ingenuity of nature and exploiting the billions of years over which natural selection has developed numerous effective biochemical conversions is one of the most successful strategies in a chemist's toolbox. However, an inability to replicate the elegance and efficiency of the oxygen-evolving complex of photosystem II (OEC-PSII) in its oxidation of water into O2 is a significant bottleneck in the development of a closed-loop sustainable energy cycle. Here, we present an artificial metallosupramolecular macrocycle that gathers three Ru(bda) centres (bda = 2,2′-bipyridine-6,6′-dicarboxylic acid) that catalyses water oxidation. The macrocyclic architecture accelerates the rate of water oxidation via a water nucleophilic attack mechanism, similar to the mechanism exhibited by OEC-PSII, and reaches remarkable catalytic turnover frequencies >100 s–1. Photo-driven water oxidation yields outstanding activity, even in the nM concentration regime, with a turnover number of >1,255 and turnover frequency of >13.1 s–1.

  @article{schulze2016supramolecular, abstract = {Mimicking the ingenuity of nature and exploiting the billions of years over which natural selection has developed numerous effective biochemical conversions is one of the most successful strategies in a chemist's toolbox. However, an inability to replicate the elegance and efficiency of the oxygen-evolving complex of photosystem II (OEC-PSII) in its oxidation of water into O2 is a significant bottleneck in the development of a closed-loop sustainable energy cycle. Here, we present an artificial metallosupramolecular macrocycle that gathers three Ru(bda) centres (bda = 2,2′-bipyridine-6,6′-dicarboxylic acid) that catalyses water oxidation. The macrocyclic architecture accelerates the rate of water oxidation via a water nucleophilic attack mechanism, similar to the mechanism exhibited by OEC-PSII, and reaches remarkable catalytic turnover frequencies >100 s–1. Photo-driven water oxidation yields outstanding activity, even in the nM concentration regime, with a turnover number of >1,255 and turnover frequency of >13.1 s–1.}, author = {Schulze, Marcus and Kunz, Valentin and Frischmann, Peter D. and Würthner, Frank}, journal = {Nat Chem}, keywords = {myown}, month = {06}, number = 6, pages = {576–583}, publisher = {Nature Publishing Group}, title = {A supramolecular ruthenium macrocycle with high catalytic activity for water oxidation that mechanistically mimics photosystem II}, volume = 8, year = 2016 }

  %0 Journal Article %1 schulze2016supramolecular %A Schulze, Marcus %A Kunz, Valentin %A Frischmann, Peter D. %A Würthner, Frank %D 2016 %I Nature Publishing Group %J Nat Chem %N 6 %P 576--583 %T A supramolecular ruthenium macrocycle with high catalytic activity for water oxidation that mechanistically mimics photosystem II %U http://dx.doi.org/10.1038/nchem.2503 %V 8 %X Mimicking the ingenuity of nature and exploiting the billions of years over which natural selection has developed numerous effective biochemical conversions is one of the most successful strategies in a chemist's toolbox. However, an inability to replicate the elegance and efficiency of the oxygen-evolving complex of photosystem II (OEC-PSII) in its oxidation of water into O2 is a significant bottleneck in the development of a closed-loop sustainable energy cycle. Here, we present an artificial metallosupramolecular macrocycle that gathers three Ru(bda) centres (bda = 2,2′-bipyridine-6,6′-dicarboxylic acid) that catalyses water oxidation. The macrocyclic architecture accelerates the rate of water oxidation via a water nucleophilic attack mechanism, similar to the mechanism exhibited by OEC-PSII, and reaches remarkable catalytic turnover frequencies >100 s–1. Photo-driven water oxidation yields outstanding activity, even in the nM concentration regime, with a turnover number of >1,255 and turnover frequency of >13.1 s–1.
• Exciton-Vibrational Couplings in Homo- and Heterodimer Stacks of Perylene Bisimide Dyes within Cyclophanes: Studies on Absorption Properties and Theoretical Analysis. Bialas, David; Brüning, Christoph; Schlosser, Felix; Fimmel, Benjamin; Thein, Johannes; Engel, Volker; Würthner, Frank. In Chemistry – A European Journal, 22(42), pp. 15011–15018. 2016.
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  The optical properties of a series of three cyclophanes comprising either identical or different perylene bisimide (PBI) chromophores were studied by UV/Vis absorption spectroscopy and their distinctive spectral features were analyzed. All the investigated cyclophanes show significantly different absorption features with respect to the corresponding constituent PBI monomers indicating strong coupling interactions between the PBI units within the cyclophanes. DFT calculations suggest a π-stacked arrangement of the PBI units at close van der Waals distance in the cyclophanes with rotational displacement. Simulations of the absorption spectra based on time-dependent quantum mechanics properly reproduced the experimental spectra, revealing exciton-vibrational coupling between the chromophores both in homo- and heterodimer stacks. The PBI cyclophane comprising two different PBI chromophores represents the first example of a PBI heterodimer stack for which the exciton coupling has been investigated. The quantum dynamics analysis reveals that exciton coupling in heteroaggregates is indeed of similar strength as for homoaggregates.

  @article{CHEM:CHEM201603205, abstract = {The optical properties of a series of three cyclophanes comprising either identical or different perylene bisimide (PBI) chromophores were studied by UV/Vis absorption spectroscopy and their distinctive spectral features were analyzed. All the investigated cyclophanes show significantly different absorption features with respect to the corresponding constituent PBI monomers indicating strong coupling interactions between the PBI units within the cyclophanes. DFT calculations suggest a π-stacked arrangement of the PBI units at close van der Waals distance in the cyclophanes with rotational displacement. Simulations of the absorption spectra based on time-dependent quantum mechanics properly reproduced the experimental spectra, revealing exciton-vibrational coupling between the chromophores both in homo- and heterodimer stacks. The PBI cyclophane comprising two different PBI chromophores represents the first example of a PBI heterodimer stack for which the exciton coupling has been investigated. The quantum dynamics analysis reveals that exciton coupling in heteroaggregates is indeed of similar strength as for homoaggregates.}, author = {Bialas, David and Brüning, Christoph and Schlosser, Felix and Fimmel, Benjamin and Thein, Johannes and Engel, Volker and Würthner, Frank}, journal = {Chemistry – A European Journal}, keywords = {myown}, number = 42, pages = {15011–15018}, title = {Exciton-Vibrational Couplings in Homo- and Heterodimer Stacks of Perylene Bisimide Dyes within Cyclophanes: Studies on Absorption Properties and Theoretical Analysis}, volume = 22, year = 2016 }

  %0 Journal Article %1 CHEM:CHEM201603205 %A Bialas, David %A Brüning, Christoph %A Schlosser, Felix %A Fimmel, Benjamin %A Thein, Johannes %A Engel, Volker %A Würthner, Frank %D 2016 %J Chemistry – A European Journal %N 42 %P 15011--15018 %R 10.1002/chem.201603205 %T Exciton-Vibrational Couplings in Homo- and Heterodimer Stacks of Perylene Bisimide Dyes within Cyclophanes: Studies on Absorption Properties and Theoretical Analysis %U http://dx.doi.org/10.1002/chem.201603205 %V 22 %X The optical properties of a series of three cyclophanes comprising either identical or different perylene bisimide (PBI) chromophores were studied by UV/Vis absorption spectroscopy and their distinctive spectral features were analyzed. All the investigated cyclophanes show significantly different absorption features with respect to the corresponding constituent PBI monomers indicating strong coupling interactions between the PBI units within the cyclophanes. DFT calculations suggest a π-stacked arrangement of the PBI units at close van der Waals distance in the cyclophanes with rotational displacement. Simulations of the absorption spectra based on time-dependent quantum mechanics properly reproduced the experimental spectra, revealing exciton-vibrational coupling between the chromophores both in homo- and heterodimer stacks. The PBI cyclophane comprising two different PBI chromophores represents the first example of a PBI heterodimer stack for which the exciton coupling has been investigated. The quantum dynamics analysis reveals that exciton coupling in heteroaggregates is indeed of similar strength as for homoaggregates.
• High performance A-D-A oligothiophene-based organic solar cells employing two-step annealing and solution-processable copper thiocyanate (CuSCN) as an interfacial hole transporting layer. Mishra, Amaresh; Rana, Tushar; Looser, Annika; Stolte, Matthias; Würthner, Frank; Bauerle, Peter; Sharma, Ganesh D. In J. Mater. Chem. A, 4(44), pp. 17344–17353. 2016.
  • [ Abstract ]
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  Two acceptor-donor-acceptor (A-D-A)-type oligomers 1 and 2 comprising dithieno[3,2-b:2[prime or minute],3[prime or minute]-d]pyrrole as a central unit and dicyanovinylene (DCV) or 1,3-indanedione as terminal acceptor groups have been synthesized for use as a donor in a solution-processed bulk-heterojunction (BHJ) solar cell in combination with [6,6]-phenyl-C71-butyric acid methyl ester (PC71BM) as an acceptor. By employing PEDOT:PSS as a HTL and two-step annealing treatment i.e. thermal annealing followed by solvent vapor annealing (TSA) of the active layer the power conversion efficiencies (PCEs) were significantly improved from 3.72% to 6.95% for 1 and 4.18% to 7.54% for 2. The improvement of the PCE was mainly due to the increase in JSC and FF values which can be attributed to the re-organization of the donor material within the blend leading to balanced charge transport and improved crystallinity of the donor in the active layer. The influence of TSA on the degree of crystallinity and blend morphology was investigated by UV-Vis absorption spectroscopy, X-ray diffraction (XRD) and transmission electron microscopy (TEM). When PEDOT:PSS was replaced by CuSCN as the HTL, a further enhancement of the photovoltaic parameters is realized leading to an increase in the PCE to 7.63% for 1 and 8.22% for 2. These results not only provide important insight into the influence of the two-step annealing process on molecular packing and charge transport properties, but also reveal the significance of CuSCN as the HTL on the device performance of tailored molecular materials.

  @article{C6TA07640H, abstract = {Two acceptor-donor-acceptor (A-D-A)-type oligomers 1 and 2 comprising dithieno[3{,}2-b:2[prime or minute]{,}3[prime or minute]-d]pyrrole as a central unit and dicyanovinylene (DCV) or 1{,}3-indanedione as terminal acceptor groups have been synthesized for use as a donor in a solution-processed bulk-heterojunction (BHJ) solar cell in combination with [6{,}6]-phenyl-C71-butyric acid methyl ester (PC71BM) as an acceptor. By employing PEDOT:PSS as a HTL and two-step annealing treatment i.e. thermal annealing followed by solvent vapor annealing (TSA) of the active layer the power conversion efficiencies (PCEs) were significantly improved from 3.72% to 6.95% for 1 and 4.18% to 7.54% for 2. The improvement of the PCE was mainly due to the increase in JSC and FF values which can be attributed to the re-organization of the donor material within the blend leading to balanced charge transport and improved crystallinity of the donor in the active layer. The influence of TSA on the degree of crystallinity and blend morphology was investigated by UV-Vis absorption spectroscopy{,} X-ray diffraction (XRD) and transmission electron microscopy (TEM). When PEDOT:PSS was replaced by CuSCN as the HTL{,} a further enhancement of the photovoltaic parameters is realized leading to an increase in the PCE to 7.63% for 1 and 8.22% for 2. These results not only provide important insight into the influence of the two-step annealing process on molecular packing and charge transport properties{,} but also reveal the significance of CuSCN as the HTL on the device performance of tailored molecular materials.}, author = {Mishra, Amaresh and Rana, Tushar and Looser, Annika and Stolte, Matthias and Würthner, Frank and Bauerle, Peter and Sharma, Ganesh D.}, journal = {J. Mater. Chem. A}, keywords = {myown}, number = 44, pages = {17344-17353}, publisher = {The Royal Society of Chemistry}, title = {High performance A-D-A oligothiophene-based organic solar cells employing two-step annealing and solution-processable copper thiocyanate (CuSCN) as an interfacial hole transporting layer}, volume = 4, year = 2016 }

  %0 Journal Article %1 C6TA07640H %A Mishra, Amaresh %A Rana, Tushar %A Looser, Annika %A Stolte, Matthias %A Würthner, Frank %A Bauerle, Peter %A Sharma, Ganesh D. %D 2016 %I The Royal Society of Chemistry %J J. Mater. Chem. A %N 44 %P 17344-17353 %R 10.1039/C6TA07640H %T High performance A-D-A oligothiophene-based organic solar cells employing two-step annealing and solution-processable copper thiocyanate (CuSCN) as an interfacial hole transporting layer %U http://dx.doi.org/10.1039/C6TA07640H %V 4 %X Two acceptor-donor-acceptor (A-D-A)-type oligomers 1 and 2 comprising dithieno[3,2-b:2[prime or minute],3[prime or minute]-d]pyrrole as a central unit and dicyanovinylene (DCV) or 1,3-indanedione as terminal acceptor groups have been synthesized for use as a donor in a solution-processed bulk-heterojunction (BHJ) solar cell in combination with [6,6]-phenyl-C71-butyric acid methyl ester (PC71BM) as an acceptor. By employing PEDOT:PSS as a HTL and two-step annealing treatment i.e. thermal annealing followed by solvent vapor annealing (TSA) of the active layer the power conversion efficiencies (PCEs) were significantly improved from 3.72% to 6.95% for 1 and 4.18% to 7.54% for 2. The improvement of the PCE was mainly due to the increase in JSC and FF values which can be attributed to the re-organization of the donor material within the blend leading to balanced charge transport and improved crystallinity of the donor in the active layer. The influence of TSA on the degree of crystallinity and blend morphology was investigated by UV-Vis absorption spectroscopy, X-ray diffraction (XRD) and transmission electron microscopy (TEM). When PEDOT:PSS was replaced by CuSCN as the HTL, a further enhancement of the photovoltaic parameters is realized leading to an increase in the PCE to 7.63% for 1 and 8.22% for 2. These results not only provide important insight into the influence of the two-step annealing process on molecular packing and charge transport properties, but also reveal the significance of CuSCN as the HTL on the device performance of tailored molecular materials.
• Conformational Switching of π-Conjugated Junctions from Merocyanine to Cyanine States by Solvent Polarity. Arjona-Esteban, Alhama; Stolte, Matthias; Würthner, Frank. In Angew. Chem. Int. Ed., 55(7), pp. 2470–2473. 2016.
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  Directed by the solvent polarity, the prevalent conformation of a polymethine dye bearing a branched π-conjugated junction can be switched from a heptamethine donor–acceptor (DA) merocyanine-type π-conjugated system to a nonamethine DAD cyanine-type π-conjugated scaffold. Concomitantly the absorption maximum shifts from 585 nm in dichloromethane to 748 nm in methanol solution.

  @article{ANIE:ANIE201510620, abstract = {Directed by the solvent polarity, the prevalent conformation of a polymethine dye bearing a branched π-conjugated junction can be switched from a heptamethine donor–acceptor (DA) merocyanine-type π-conjugated system to a nonamethine DAD cyanine-type π-conjugated scaffold. Concomitantly the absorption maximum shifts from 585 nm in dichloromethane to 748 nm in methanol solution.}, author = {Arjona-Esteban, Alhama and Stolte, Matthias and Würthner, Frank}, journal = {Angew. Chem. Int. Ed.}, keywords = {solvatochromism}, number = 7, pages = {2470–2473}, title = {Conformational Switching of π-Conjugated Junctions from Merocyanine to Cyanine States by Solvent Polarity}, volume = 55, year = 2016 }

  %0 Journal Article %1 ANIE:ANIE201510620 %A Arjona-Esteban, Alhama %A Stolte, Matthias %A Würthner, Frank %D 2016 %J Angew. Chem. Int. Ed. %N 7 %P 2470--2473 %R 10.1002/anie.201510620 %T Conformational Switching of π-Conjugated Junctions from Merocyanine to Cyanine States by Solvent Polarity %U http://dx.doi.org/10.1002/anie.201510620 %V 55 %X Directed by the solvent polarity, the prevalent conformation of a polymethine dye bearing a branched π-conjugated junction can be switched from a heptamethine donor–acceptor (DA) merocyanine-type π-conjugated system to a nonamethine DAD cyanine-type π-conjugated scaffold. Concomitantly the absorption maximum shifts from 585 nm in dichloromethane to 748 nm in methanol solution.
• Biphasic aggregation of a perylene bisimide dye identified by exciton-vibrational spectra. Plotz, P.-A.; Polyutov, S. P.; Ivanov, S. D.; Fennel, F.; Wolter, S.; Niehaus, T.; Xie, Z.; Lochbrunner, S.; Würthner, F.; Kuhn, O. In Phys. Chem. Chem. Phys., 18(36), pp. 25110–25119. 2016.
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  The quantum efficiency of light emission is a crucial parameter of supramolecular aggregates that can be tuned by the molecular design of the monomeric species. Here, we report on a strong variation of the fluorescence quantum yield due to different phases of aggregation for the case of a perylene bisimide dye. In particular, a change of the dominant aggregation character from H- to J-type within the first aggregation steps is found, explaining the observed dramatic change in quantum yield. This behaviour is rationalised by means of a systematic study of the intermolecular potential energy surfaces using the time-dependent density functional based tight-binding (TD-DFTB) method. This provides a correlation between structural changes and a coupling strength and supports the notion of H-type stacked dimers and J-type stack-slipped dimers. The exciton-vibrational level structure is modelled by means of an excitonic dimer model including two effective vibrational modes per monomer. Calculated absorption and fluorescence spectra are found to be in reasonable agreement with experimental ones, thus supporting the conclusion on the aggregation behaviour.

  @article{C6CP04898F, abstract = {The quantum efficiency of light emission is a crucial parameter of supramolecular aggregates that can be tuned by the molecular design of the monomeric species. Here{,} we report on a strong variation of the fluorescence quantum yield due to different phases of aggregation for the case of a perylene bisimide dye. In particular{,} a change of the dominant aggregation character from H- to J-type within the first aggregation steps is found{,} explaining the observed dramatic change in quantum yield. This behaviour is rationalised by means of a systematic study of the intermolecular potential energy surfaces using the time-dependent density functional based tight-binding (TD-DFTB) method. This provides a correlation between structural changes and a coupling strength and supports the notion of H-type stacked dimers and J-type stack-slipped dimers. The exciton-vibrational level structure is modelled by means of an excitonic dimer model including two effective vibrational modes per monomer. Calculated absorption and fluorescence spectra are found to be in reasonable agreement with experimental ones{,} thus supporting the conclusion on the aggregation behaviour.}, author = {Plotz, P.-A. and Polyutov, S. P. and Ivanov, S. D. and Fennel, F. and Wolter, S. and Niehaus, T. and Xie, Z. and Lochbrunner, S. and Würthner, F. and Kuhn, O.}, journal = {Phys. Chem. Chem. Phys.}, keywords = {myown}, number = 36, pages = {25110-25119}, publisher = {The Royal Society of Chemistry}, title = {Biphasic aggregation of a perylene bisimide dye identified by exciton-vibrational spectra}, volume = 18, year = 2016 }

  %0 Journal Article %1 C6CP04898F %A Plotz, P.-A. %A Polyutov, S. P. %A Ivanov, S. D. %A Fennel, F. %A Wolter, S. %A Niehaus, T. %A Xie, Z. %A Lochbrunner, S. %A Würthner, F. %A Kuhn, O. %D 2016 %I The Royal Society of Chemistry %J Phys. Chem. Chem. Phys. %N 36 %P 25110-25119 %R 10.1039/C6CP04898F %T Biphasic aggregation of a perylene bisimide dye identified by exciton-vibrational spectra %U http://dx.doi.org/10.1039/C6CP04898F %V 18 %X The quantum efficiency of light emission is a crucial parameter of supramolecular aggregates that can be tuned by the molecular design of the monomeric species. Here, we report on a strong variation of the fluorescence quantum yield due to different phases of aggregation for the case of a perylene bisimide dye. In particular, a change of the dominant aggregation character from H- to J-type within the first aggregation steps is found, explaining the observed dramatic change in quantum yield. This behaviour is rationalised by means of a systematic study of the intermolecular potential energy surfaces using the time-dependent density functional based tight-binding (TD-DFTB) method. This provides a correlation between structural changes and a coupling strength and supports the notion of H-type stacked dimers and J-type stack-slipped dimers. The exciton-vibrational level structure is modelled by means of an excitonic dimer model including two effective vibrational modes per monomer. Calculated absorption and fluorescence spectra are found to be in reasonable agreement with experimental ones, thus supporting the conclusion on the aggregation behaviour.
• Structural and quantum chemical analysis of exciton coupling in homo- and heteroaggregate stacks of merocyanines. Bialas, David; Zitzler-Kunkel, André; Kirchner, Eva; Schmidt, David; Würthner, Frank. In Nature Communications, 7, p. 12949-. 2016.
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  Exciton coupling is of fundamental importance and determines functional properties of organic dyes in (opto-)electronic and photovoltaic devices. Here we show that strong exciton coupling is not limited to the situation of equal chromophores as often assumed. Quadruple dye stacks were obtained from two bis(merocyanine) dyes with same or different chromophores, respectively, which dimerize in less-polar solvents resulting in the respective homo- and heteroaggregates. The structures of the quadruple dye stacks were assigned by NMR techniques and unambiguously confirmed by single-crystal X-ray analysis. The heteroaggregate stack formed from the bis(merocyanine) bearing two different chromophores exhibits remarkably different ultraviolet/vis absorption bands compared with those of the homoaggregate of the bis(merocyanine) comprising two identical chromophores. Quantum chemical analysis based on an extension of Kasha’s exciton theory appropriately describes the absorption properties of both types of stacks revealing strong exciton coupling also between different chromophores within the heteroaggregate.

  @article{bialas2016structural, abstract = {Exciton coupling is of fundamental importance and determines functional properties of organic dyes in (opto-)electronic and photovoltaic devices. Here we show that strong exciton coupling is not limited to the situation of equal chromophores as often assumed. Quadruple dye stacks were obtained from two bis(merocyanine) dyes with same or different chromophores, respectively, which dimerize in less-polar solvents resulting in the respective homo- and heteroaggregates. The structures of the quadruple dye stacks were assigned by NMR techniques and unambiguously confirmed by single-crystal X-ray analysis. The heteroaggregate stack formed from the bis(merocyanine) bearing two different chromophores exhibits remarkably different ultraviolet/vis absorption bands compared with those of the homoaggregate of the bis(merocyanine) comprising two identical chromophores. Quantum chemical analysis based on an extension of Kasha’s exciton theory appropriately describes the absorption properties of both types of stacks revealing strong exciton coupling also between different chromophores within the heteroaggregate.}, author = {Bialas, David and Zitzler-Kunkel, André and Kirchner, Eva and Schmidt, David and Würthner, Frank}, journal = {Nature Communications}, keywords = {myown}, month = {09}, pages = {12949–}, publisher = {The Author(s)}, title = {Structural and quantum chemical analysis of exciton coupling in homo- and heteroaggregate stacks of merocyanines}, volume = 7, year = 2016 }

  %0 Journal Article %1 bialas2016structural %A Bialas, David %A Zitzler-Kunkel, André %A Kirchner, Eva %A Schmidt, David %A Würthner, Frank %D 2016 %I The Author(s) %J Nature Communications %P 12949-- %R doi:10.1038/ncomms12949 %T Structural and quantum chemical analysis of exciton coupling in homo- and heteroaggregate stacks of merocyanines %U http://dx.doi.org/10.1038/ncomms12949 %V 7 %X Exciton coupling is of fundamental importance and determines functional properties of organic dyes in (opto-)electronic and photovoltaic devices. Here we show that strong exciton coupling is not limited to the situation of equal chromophores as often assumed. Quadruple dye stacks were obtained from two bis(merocyanine) dyes with same or different chromophores, respectively, which dimerize in less-polar solvents resulting in the respective homo- and heteroaggregates. The structures of the quadruple dye stacks were assigned by NMR techniques and unambiguously confirmed by single-crystal X-ray analysis. The heteroaggregate stack formed from the bis(merocyanine) bearing two different chromophores exhibits remarkably different ultraviolet/vis absorption bands compared with those of the homoaggregate of the bis(merocyanine) comprising two identical chromophores. Quantum chemical analysis based on an extension of Kasha’s exciton theory appropriately describes the absorption properties of both types of stacks revealing strong exciton coupling also between different chromophores within the heteroaggregate.
• An Electron-Poor C64 Nanographene by Palladium-Catalyzed Cascade C−C Bond Formation: One-Pot Synthesis and Single-Crystal Structure Analysis. Seifert, Sabine; Shoyama, Kazutaka; Schmidt, David; Würthner, Frank. In Angew. Chem. Int. Ed., 128(22), pp. 6500–6505. 2016.
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  • [ DOI ]
  Herein, we report the one-pot synthesis of an electron-poor nanographene containing dicarboximide groups at the corners. We efficiently combined palladium-catalyzed Suzuki–Miyaura cross-coupling and dehydrohalogenation to synthesize an extended two-dimensional π-scaffold of defined size in a single chemical operation starting from N-(2,6-diisopropylphenyl)-4,5-dibromo-1,8-naphthalimide and a tetrasubstituted pyrene boronic acid ester as readily accessible starting materials. The reaction of these precursors under the conditions commonly used for Suzuki–Miyaura cross-coupling afforded a C64 nanographene through the formation of ten C−C bonds in a one-pot process. Single-crystal X-ray analysis unequivocally confirmed the structure of this unique extended aromatic molecule with a planar geometry. The optical and electrochemical properties of this largest ever synthesized planar electron-poor nanographene skeleton were also analyzed.

  @article{ANGE:ANGE201601433, abstract = {Herein, we report the one-pot synthesis of an electron-poor nanographene containing dicarboximide groups at the corners. We efficiently combined palladium-catalyzed Suzuki–Miyaura cross-coupling and dehydrohalogenation to synthesize an extended two-dimensional π-scaffold of defined size in a single chemical operation starting from N-(2,6-diisopropylphenyl)-4,5-dibromo-1,8-naphthalimide and a tetrasubstituted pyrene boronic acid ester as readily accessible starting materials. The reaction of these precursors under the conditions commonly used for Suzuki–Miyaura cross-coupling afforded a C64 nanographene through the formation of ten C−C bonds in a one-pot process. Single-crystal X-ray analysis unequivocally confirmed the structure of this unique extended aromatic molecule with a planar geometry. The optical and electrochemical properties of this largest ever synthesized planar electron-poor nanographene skeleton were also analyzed.}, author = {Seifert, Sabine and Shoyama, Kazutaka and Schmidt, David and Würthner, Frank}, journal = {Angew. Chem. Int. Ed.}, keywords = {myown}, number = 22, pages = {6500–6505}, title = {An Electron-Poor C64 Nanographene by Palladium-Catalyzed Cascade C−C Bond Formation: One-Pot Synthesis and Single-Crystal Structure Analysis}, volume = 128, year = 2016 }

  %0 Journal Article %1 ANGE:ANGE201601433 %A Seifert, Sabine %A Shoyama, Kazutaka %A Schmidt, David %A Würthner, Frank %D 2016 %J Angew. Chem. Int. Ed. %N 22 %P 6500--6505 %R 10.1002/anie.201601433 %T An Electron-Poor C64 Nanographene by Palladium-Catalyzed Cascade C−C Bond Formation: One-Pot Synthesis and Single-Crystal Structure Analysis %U https://onlinelibrary.wiley.com/doi/full/10.1002/anie.201601433 %V 128 %X Herein, we report the one-pot synthesis of an electron-poor nanographene containing dicarboximide groups at the corners. We efficiently combined palladium-catalyzed Suzuki–Miyaura cross-coupling and dehydrohalogenation to synthesize an extended two-dimensional π-scaffold of defined size in a single chemical operation starting from N-(2,6-diisopropylphenyl)-4,5-dibromo-1,8-naphthalimide and a tetrasubstituted pyrene boronic acid ester as readily accessible starting materials. The reaction of these precursors under the conditions commonly used for Suzuki–Miyaura cross-coupling afforded a C64 nanographene through the formation of ten C−C bonds in a one-pot process. Single-crystal X-ray analysis unequivocally confirmed the structure of this unique extended aromatic molecule with a planar geometry. The optical and electrochemical properties of this largest ever synthesized planar electron-poor nanographene skeleton were also analyzed.
• Tracing Single Electrons in a Disordered Polymer Film at Room Temperature. Wilma, Kevin; Issac, Abey; Chen, Zhijian; Würthner, Frank; Hildner, Richard; Köhler, Jürgen. In J. Phys. Chem. Lett., 7(8), pp. 1478–1483. 2016.

  PMID: 27035727
  • [ Abstract ]
  • [ BibTeX ]
  • [ EndNote ]
  • [ DOI ]
  The transport of charges lies at the heart of essentially all modern (opto-) electronic devices. Although inorganic semiconductors built the basis for current technologies, organic materials have become increasingly important in recent years. However, organic matter is often highly disordered, which directly impacts the charge carrier dynamics. To understand and optimize device performance, detailed knowledge of the transport mechanisms of charge carriers in disordered matter is therefore of crucial importance. Here we report on the observation of the motion of single electrons within a disordered polymer film at room temperature, using single organic chromophores as probe molecules. The migration of a single electron gives rise to a varying electric field in its vicinity, which is registered via a shift of the emission spectra (Stark shift) of a chromophore. The spectral shifts allow us to determine the electron mobility and reveal for each nanoenvironment a distinct number of different possible electron-transfer pathways within the rugged energy landscape of the disordered polymer matrix.

  @article{doi:10.1021/acs.jpclett.6b00446, abstract = {The transport of charges lies at the heart of essentially all modern (opto-) electronic devices. Although inorganic semiconductors built the basis for current technologies, organic materials have become increasingly important in recent years. However, organic matter is often highly disordered, which directly impacts the charge carrier dynamics. To understand and optimize device performance, detailed knowledge of the transport mechanisms of charge carriers in disordered matter is therefore of crucial importance. Here we report on the observation of the motion of single electrons within a disordered polymer film at room temperature, using single organic chromophores as probe molecules. The migration of a single electron gives rise to a varying electric field in its vicinity, which is registered via a shift of the emission spectra (Stark shift) of a chromophore. The spectral shifts allow us to determine the electron mobility and reveal for each nanoenvironment a distinct number of different possible electron-transfer pathways within the rugged energy landscape of the disordered polymer matrix.}, author = {Wilma, Kevin and Issac, Abey and Chen, Zhijian and Würthner, Frank and Hildner, Richard and Köhler, Jürgen}, journal = {J. Phys. Chem. Lett.}, keywords = {myown}, note = {PMID: 27035727}, number = 8, pages = {1478-1483}, title = {Tracing Single Electrons in a Disordered Polymer Film at Room Temperature}, volume = 7, year = 2016 }

  %0 Journal Article %1 doi:10.1021/acs.jpclett.6b00446 %A Wilma, Kevin %A Issac, Abey %A Chen, Zhijian %A Würthner, Frank %A Hildner, Richard %A Köhler, Jürgen %D 2016 %J J. Phys. Chem. Lett. %N 8 %P 1478-1483 %R 10.1021/acs.jpclett.6b00446 %T Tracing Single Electrons in a Disordered Polymer Film at Room Temperature %U http://dx.doi.org/10.1021/acs.jpclett.6b00446 %V 7 %X The transport of charges lies at the heart of essentially all modern (opto-) electronic devices. Although inorganic semiconductors built the basis for current technologies, organic materials have become increasingly important in recent years. However, organic matter is often highly disordered, which directly impacts the charge carrier dynamics. To understand and optimize device performance, detailed knowledge of the transport mechanisms of charge carriers in disordered matter is therefore of crucial importance. Here we report on the observation of the motion of single electrons within a disordered polymer film at room temperature, using single organic chromophores as probe molecules. The migration of a single electron gives rise to a varying electric field in its vicinity, which is registered via a shift of the emission spectra (Stark shift) of a chromophore. The spectral shifts allow us to determine the electron mobility and reveal for each nanoenvironment a distinct number of different possible electron-transfer pathways within the rugged energy landscape of the disordered polymer matrix.
• Guest and solvent modulated photo-driven charge separation and triplet generation in a perylene bisimide cyclophane. Spenst, Peter; Young, Ryan M.; Wasielewski, Michael R.; Würthner, Frank. In Chem. Sci., 7(8), pp. 5428–5434. 2016.
  • [ Abstract ]
  • [ BibTeX ]
  • [ EndNote ]
  • [ DOI ]
  Cofacial positioning of two perylene bisimide (PBI) chromophores at a distance of 6.5 A in a cyclophane structure prohibits the otherwise common excimer formation and directs photoexcited singlet state relaxation towards intramolecular symmetry-breaking charge separation ([small tau]CS = 161 +/- 4 ps) in polar CH2Cl2, which is thermodynamically favored with a Gibbs free energy of [capital Delta]GCS = -0.32 eV. The charges then recombine slowly in [small tau]CR = 8.90 +/- 0.06 ns to form the PBI triplet excited state, which can be used subsequently to generate singlet oxygen in 27% quantum yield. This sequence of events is eliminated by dissolving the PBI cyclophane in non-polar toluene, where only excited singlet state decay occurs. In contrast, complexation of electron-rich aromatic hydrocarbons by the host PBI cyclophane followed by photoexcitation of PBI results in ultrafast electron transfer (<10 ps) from the guest to the PBI in CH2Cl2. The rate constants for charge separation and recombination increase as the guest molecules become easier to oxidize, demonstrating that charge separation occurs close to the peak of the Marcus curve and the recombination lies far into the Marcus inverted region.

  @article{C6SC01574C, abstract = {Cofacial positioning of two perylene bisimide (PBI) chromophores at a distance of 6.5 A in a cyclophane structure prohibits the otherwise common excimer formation and directs photoexcited singlet state relaxation towards intramolecular symmetry-breaking charge separation ([small tau]CS = 161 +/- 4 ps) in polar CH2Cl2{,} which is thermodynamically favored with a Gibbs free energy of [capital Delta]GCS = -0.32 eV. The charges then recombine slowly in [small tau]CR = 8.90 +/- 0.06 ns to form the PBI triplet excited state{,} which can be used subsequently to generate singlet oxygen in 27% quantum yield. This sequence of events is eliminated by dissolving the PBI cyclophane in non-polar toluene{,} where only excited singlet state decay occurs. In contrast{,} complexation of electron-rich aromatic hydrocarbons by the host PBI cyclophane followed by photoexcitation of PBI results in ultrafast electron transfer (<10 ps) from the guest to the PBI in CH2Cl2. The rate constants for charge separation and recombination increase as the guest molecules become easier to oxidize{,} demonstrating that charge separation occurs close to the peak of the Marcus curve and the recombination lies far into the Marcus inverted region.}, author = {Spenst, Peter and Young, Ryan M. and Wasielewski, Michael R. and Würthner, Frank}, journal = {Chem. Sci.}, keywords = {myown}, number = 8, pages = {5428-5434}, publisher = {The Royal Society of Chemistry}, title = {Guest and solvent modulated photo-driven charge separation and triplet generation in a perylene bisimide cyclophane}, volume = 7, year = 2016 }

  %0 Journal Article %1 C6SC01574C %A Spenst, Peter %A Young, Ryan M. %A Wasielewski, Michael R. %A Würthner, Frank %D 2016 %I The Royal Society of Chemistry %J Chem. Sci. %N 8 %P 5428-5434 %R 10.1039/C6SC01574C %T Guest and solvent modulated photo-driven charge separation and triplet generation in a perylene bisimide cyclophane %U http://dx.doi.org/10.1039/C6SC01574C %V 7 %X Cofacial positioning of two perylene bisimide (PBI) chromophores at a distance of 6.5 A in a cyclophane structure prohibits the otherwise common excimer formation and directs photoexcited singlet state relaxation towards intramolecular symmetry-breaking charge separation ([small tau]CS = 161 +/- 4 ps) in polar CH2Cl2, which is thermodynamically favored with a Gibbs free energy of [capital Delta]GCS = -0.32 eV. The charges then recombine slowly in [small tau]CR = 8.90 +/- 0.06 ns to form the PBI triplet excited state, which can be used subsequently to generate singlet oxygen in 27% quantum yield. This sequence of events is eliminated by dissolving the PBI cyclophane in non-polar toluene, where only excited singlet state decay occurs. In contrast, complexation of electron-rich aromatic hydrocarbons by the host PBI cyclophane followed by photoexcitation of PBI results in ultrafast electron transfer (<10 ps) from the guest to the PBI in CH2Cl2. The rate constants for charge separation and recombination increase as the guest molecules become easier to oxidize, demonstrating that charge separation occurs close to the peak of the Marcus curve and the recombination lies far into the Marcus inverted region.
• Dipole–Dipole Interaction Driven Self-Assembly of Merocyanine Dyes: From Dimers to Nanoscale Objects and Supramolecular Materials. Würthner, Frank. In Accounts of Chemical Research, 49(5), pp. 868–876. 2016.

  PMID: 27064423
  • [ Abstract ]
  • [ BibTeX ]
  • [ EndNote ]
  • [ DOI ]
  Conspectusπ-Conjugation between heterocyclic donor (D) and acceptor (A) groups via a polymethine chain leads to dyes with dipole moments greater than 10 D. These dipole moments direct the self-assembly of the dyes into antiparallel dimer aggregates, even in dilute solution, with binding strengths that are far beyond those observed for other π-scaffolds whose self-assembly is driven primarily by dispersion forces. The combination of directionality and exceptional binding strength of dipolar interactions between D-π-A dyes indeed resembles the situation of the hydrogen bond. Thus, similar to the latter, dipolar interactions between merocyanine dyes, a unique class of D-π-A chromophores, can be utilized to construct sophisticated supramolecular architectures of predictable geometry, particularly in low polarity environments.For bis(merocyanine) dyes it has been demonstrated that the self-assembly pathway is encoded in the tether between the two constituent merocyanine chromophores. If the tether enables the antiparallel stacking of the two appended dyes, folding takes place, which may be followed by further self-assembly into extended H-aggregate π-stacks at higher concentrations in solvents of low polarity. For tethers that do not support folding, the formation of bimolecular complexes of four merocyanine units, cyclic oligomers, and supramolecular polymers has been observed. For the former case, that is, formation of a bimolecular stack of four merocyanine units from tweezer-type molecules, association constants >109 M–1 were measured in chloroform. On the other hand, because only one π-face is utilized in the formation of supramolecular polymers from bis(merocyanine) dyes, higher hierarchical structures typically originate in which the other π-face is surrounded by an antiparallel π-stacked neighbor molecule.Among the observed self-assembled structures, nanorods in particular have attracted considerable attention because their self-assembly into well-defined H-aggregates falls under kinetic control and is slowed tremendously with decreasing solvent polarity. Co-assembly of achiral and chiral merocyanine building blocks or two enantiomers of a chiral merocyanine in different ratios provided insight into “majority rules” and “sergeant-and-soldiers” effects as well as the autocatalytic fiber growth process.With regard to materials applications, it is important to note that the high propensity for dipolar aggregation was disadvantageous for many envisioned applications of these dyes in the area of nonlinear optics. However, this aggregation behavior proved to be advantageous for the recently demonstrated applications of D-π-A dyes, in particular, merocyanines as p-type organic semiconductors in organic electronics and photovoltaics. Thus, organic transistors with hole mobilities >0.5 cm2/(V s) and organic solar cells with power conversion efficiencies >6\% could be achieved with merocyanine-based organic semiconductor molecules.

  @article{doi:10.1021/acs.accounts.6b00042, abstract = {Conspectusπ-Conjugation between heterocyclic donor (D) and acceptor (A) groups via a polymethine chain leads to dyes with dipole moments greater than 10 D. These dipole moments direct the self-assembly of the dyes into antiparallel dimer aggregates, even in dilute solution, with binding strengths that are far beyond those observed for other π-scaffolds whose self-assembly is driven primarily by dispersion forces. The combination of directionality and exceptional binding strength of dipolar interactions between D-π-A dyes indeed resembles the situation of the hydrogen bond. Thus, similar to the latter, dipolar interactions between merocyanine dyes, a unique class of D-π-A chromophores, can be utilized to construct sophisticated supramolecular architectures of predictable geometry, particularly in low polarity environments.For bis(merocyanine) dyes it has been demonstrated that the self-assembly pathway is encoded in the tether between the two constituent merocyanine chromophores. If the tether enables the antiparallel stacking of the two appended dyes, folding takes place, which may be followed by further self-assembly into extended H-aggregate π-stacks at higher concentrations in solvents of low polarity. For tethers that do not support folding, the formation of bimolecular complexes of four merocyanine units, cyclic oligomers, and supramolecular polymers has been observed. For the former case, that is, formation of a bimolecular stack of four merocyanine units from tweezer-type molecules, association constants >109 M–1 were measured in chloroform. On the other hand, because only one π-face is utilized in the formation of supramolecular polymers from bis(merocyanine) dyes, higher hierarchical structures typically originate in which the other π-face is surrounded by an antiparallel π-stacked neighbor molecule.Among the observed self-assembled structures, nanorods in particular have attracted considerable attention because their self-assembly into well-defined H-aggregates falls under kinetic control and is slowed tremendously with decreasing solvent polarity. Co-assembly of achiral and chiral merocyanine building blocks or two enantiomers of a chiral merocyanine in different ratios provided insight into “majority rules” and “sergeant-and-soldiers” effects as well as the autocatalytic fiber growth process.With regard to materials applications, it is important to note that the high propensity for dipolar aggregation was disadvantageous for many envisioned applications of these dyes in the area of nonlinear optics. However, this aggregation behavior proved to be advantageous for the recently demonstrated applications of D-π-A dyes, in particular, merocyanines as p-type organic semiconductors in organic electronics and photovoltaics. Thus, organic transistors with hole mobilities >0.5 cm2/(V s) and organic solar cells with power conversion efficiencies >6\% could be achieved with merocyanine-based organic semiconductor molecules.}, author = {Würthner, Frank}, journal = {Accounts of Chemical Research}, keywords = {myown}, note = {PMID: 27064423}, number = 5, pages = {868-876}, title = {Dipole–Dipole Interaction Driven Self-Assembly of Merocyanine Dyes: From Dimers to Nanoscale Objects and Supramolecular Materials}, volume = 49, year = 2016 }

  %0 Journal Article %1 doi:10.1021/acs.accounts.6b00042 %A Würthner, Frank %D 2016 %J Accounts of Chemical Research %N 5 %P 868-876 %R 10.1021/acs.accounts.6b00042 %T Dipole–Dipole Interaction Driven Self-Assembly of Merocyanine Dyes: From Dimers to Nanoscale Objects and Supramolecular Materials %U http://dx.doi.org/10.1021/acs.accounts.6b00042 %V 49 %X Conspectusπ-Conjugation between heterocyclic donor (D) and acceptor (A) groups via a polymethine chain leads to dyes with dipole moments greater than 10 D. These dipole moments direct the self-assembly of the dyes into antiparallel dimer aggregates, even in dilute solution, with binding strengths that are far beyond those observed for other π-scaffolds whose self-assembly is driven primarily by dispersion forces. The combination of directionality and exceptional binding strength of dipolar interactions between D-π-A dyes indeed resembles the situation of the hydrogen bond. Thus, similar to the latter, dipolar interactions between merocyanine dyes, a unique class of D-π-A chromophores, can be utilized to construct sophisticated supramolecular architectures of predictable geometry, particularly in low polarity environments.For bis(merocyanine) dyes it has been demonstrated that the self-assembly pathway is encoded in the tether between the two constituent merocyanine chromophores. If the tether enables the antiparallel stacking of the two appended dyes, folding takes place, which may be followed by further self-assembly into extended H-aggregate π-stacks at higher concentrations in solvents of low polarity. For tethers that do not support folding, the formation of bimolecular complexes of four merocyanine units, cyclic oligomers, and supramolecular polymers has been observed. For the former case, that is, formation of a bimolecular stack of four merocyanine units from tweezer-type molecules, association constants >109 M–1 were measured in chloroform. On the other hand, because only one π-face is utilized in the formation of supramolecular polymers from bis(merocyanine) dyes, higher hierarchical structures typically originate in which the other π-face is surrounded by an antiparallel π-stacked neighbor molecule.Among the observed self-assembled structures, nanorods in particular have attracted considerable attention because their self-assembly into well-defined H-aggregates falls under kinetic control and is slowed tremendously with decreasing solvent polarity. Co-assembly of achiral and chiral merocyanine building blocks or two enantiomers of a chiral merocyanine in different ratios provided insight into “majority rules” and “sergeant-and-soldiers” effects as well as the autocatalytic fiber growth process.With regard to materials applications, it is important to note that the high propensity for dipolar aggregation was disadvantageous for many envisioned applications of these dyes in the area of nonlinear optics. However, this aggregation behavior proved to be advantageous for the recently demonstrated applications of D-π-A dyes, in particular, merocyanines as p-type organic semiconductors in organic electronics and photovoltaics. Thus, organic transistors with hole mobilities >0.5 cm2/(V s) and organic solar cells with power conversion efficiencies >6\% could be achieved with merocyanine-based organic semiconductor molecules.
• Perylene bisimide hydrogels and lyotropic liquid crystals with temperature-responsive color change. Gorl, Daniel; Soberats, Bartolome; Herbst, Stefanie; Stepanenko, Vladimir; Würthner, Frank. In Chem. Sci., 7(11), pp. 6786–6790. 2016.
  • [ Abstract ]
  • [ BibTeX ]
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  • [ DOI ]
  The self-assembly of perylene bisimide (PBI) dyes bearing oligo ethylene glycol (OEG) units in water affords responsive functional nanostructures characterized by their lower critical solution temperature (LCST). Tuning of the LCST is realized by a supramolecular approach that relies on two structurally closely related PBI-OEG molecules. The two PBIs socially co-assemble in water and the resulting nanostructures exhibit a single LCST in between the transition temperatures of the aggregates formed by single components. This permits to precisely tune the transition from a hydrogel to a lyotropic liquid crystal state at temperatures between 26 and 51 [degree]C by adjusting the molar fraction of the two PBIs. Owing to concomitant changes in PBI-PBI interactions this phase transition affords a pronounced color change with "fluorescence-on" response that can be utilized as a smart temperature sensory system.

  @article{C6SC02249A, abstract = {The self-assembly of perylene bisimide (PBI) dyes bearing oligo ethylene glycol (OEG) units in water affords responsive functional nanostructures characterized by their lower critical solution temperature (LCST). Tuning of the LCST is realized by a supramolecular approach that relies on two structurally closely related PBI-OEG molecules. The two PBIs socially co-assemble in water and the resulting nanostructures exhibit a single LCST in between the transition temperatures of the aggregates formed by single components. This permits to precisely tune the transition from a hydrogel to a lyotropic liquid crystal state at temperatures between 26 and 51 [degree]C by adjusting the molar fraction of the two PBIs. Owing to concomitant changes in PBI-PBI interactions this phase transition affords a pronounced color change with {"}fluorescence-on{"} response that can be utilized as a smart temperature sensory system.}, author = {Gorl, Daniel and Soberats, Bartolome and Herbst, Stefanie and Stepanenko, Vladimir and Würthner, Frank}, journal = {Chem. Sci.}, keywords = {myown}, number = 11, pages = {6786-6790}, publisher = {The Royal Society of Chemistry}, title = {Perylene bisimide hydrogels and lyotropic liquid crystals with temperature-responsive color change}, volume = 7, year = 2016 }

  %0 Journal Article %1 C6SC02249A %A Gorl, Daniel %A Soberats, Bartolome %A Herbst, Stefanie %A Stepanenko, Vladimir %A Würthner, Frank %D 2016 %I The Royal Society of Chemistry %J Chem. Sci. %N 11 %P 6786-6790 %R 10.1039/C6SC02249A %T Perylene bisimide hydrogels and lyotropic liquid crystals with temperature-responsive color change %U http://dx.doi.org/10.1039/C6SC02249A %V 7 %X The self-assembly of perylene bisimide (PBI) dyes bearing oligo ethylene glycol (OEG) units in water affords responsive functional nanostructures characterized by their lower critical solution temperature (LCST). Tuning of the LCST is realized by a supramolecular approach that relies on two structurally closely related PBI-OEG molecules. The two PBIs socially co-assemble in water and the resulting nanostructures exhibit a single LCST in between the transition temperatures of the aggregates formed by single components. This permits to precisely tune the transition from a hydrogel to a lyotropic liquid crystal state at temperatures between 26 and 51 [degree]C by adjusting the molar fraction of the two PBIs. Owing to concomitant changes in PBI-PBI interactions this phase transition affords a pronounced color change with "fluorescence-on" response that can be utilized as a smart temperature sensory system.
• The role of the dipolar neighborhood on the relaxation dynamics of multichromophoric merocyanines. Koch, Federico; Steinbacher, Andreas; Consani, Cristina; Zitzler-Kunkel, Andre; Stolte, Matthias; Würthner, Frank; Brixner, Tobias. In Phys. Chem. Chem. Phys., 18(29), pp. 19820–19831. 2016.
  • [ Abstract ]
  • [ BibTeX ]
  • [ EndNote ]
  • [ DOI ]
  The interactions between different chromophores within a molecular system are crucial to comprehend relaxation dynamics, regardless if one deals with small molecules or larger systems like polymers or aggregates. We investigate a series of merocyanine molecules that contain one, two or three highly dipolar ([small mu ]g = 13.1 D) dyes in close vicinity to study the influence and origin of interactions, e.g., electronic, vibronic, or the formation of excitons. Relaxation dynamics are probed via transient absorption and coherent two-dimensional spectroscopy. Furthermore, we derive a general relaxation model which can be applied for all merocyanines under investigation and can be used as a reference point for other dipolar donor-acceptor dyes. The intramolecular charge-transfer state of the monomeric merocyanine is stabilized by dipolar neighbor molecules in the bis- and tris-chromophoric dyes.

  @article{C6CP02437H, abstract = {The interactions between different chromophores within a molecular system are crucial to comprehend relaxation dynamics{,} regardless if one deals with small molecules or larger systems like polymers or aggregates. We investigate a series of merocyanine molecules that contain one{,} two or three highly dipolar ([small mu ]g = 13.1 D) dyes in close vicinity to study the influence and origin of interactions{,} e.g.{,} electronic{,} vibronic{,} or the formation of excitons. Relaxation dynamics are probed via transient absorption and coherent two-dimensional spectroscopy. Furthermore{,} we derive a general relaxation model which can be applied for all merocyanines under investigation and can be used as a reference point for other dipolar donor-acceptor dyes. The intramolecular charge-transfer state of the monomeric merocyanine is stabilized by dipolar neighbor molecules in the bis- and tris-chromophoric dyes.}, author = {Koch, Federico and Steinbacher, Andreas and Consani, Cristina and Zitzler-Kunkel, Andre and Stolte, Matthias and Würthner, Frank and Brixner, Tobias}, journal = {Phys. Chem. Chem. Phys.}, keywords = {myown}, number = 29, pages = {19820-19831}, publisher = {The Royal Society of Chemistry}, title = {The role of the dipolar neighborhood on the relaxation dynamics of multichromophoric merocyanines}, volume = 18, year = 2016 }

  %0 Journal Article %1 C6CP02437H %A Koch, Federico %A Steinbacher, Andreas %A Consani, Cristina %A Zitzler-Kunkel, Andre %A Stolte, Matthias %A Würthner, Frank %A Brixner, Tobias %D 2016 %I The Royal Society of Chemistry %J Phys. Chem. Chem. Phys. %N 29 %P 19820-19831 %R 10.1039/C6CP02437H %T The role of the dipolar neighborhood on the relaxation dynamics of multichromophoric merocyanines %U http://dx.doi.org/10.1039/C6CP02437H %V 18 %X The interactions between different chromophores within a molecular system are crucial to comprehend relaxation dynamics, regardless if one deals with small molecules or larger systems like polymers or aggregates. We investigate a series of merocyanine molecules that contain one, two or three highly dipolar ([small mu ]g = 13.1 D) dyes in close vicinity to study the influence and origin of interactions, e.g., electronic, vibronic, or the formation of excitons. Relaxation dynamics are probed via transient absorption and coherent two-dimensional spectroscopy. Furthermore, we derive a general relaxation model which can be applied for all merocyanines under investigation and can be used as a reference point for other dipolar donor-acceptor dyes. The intramolecular charge-transfer state of the monomeric merocyanine is stabilized by dipolar neighbor molecules in the bis- and tris-chromophoric dyes.
• A cross-coupling-annulation cascade from peri-dibromonaphthalimide to pseudo-rylene bisimides. Seifert, Sabine; Schmidt, David; Würthner, Frank. In Org. Chem. Front., 3(11), pp. 1435–1442. 2016.
  • [ Abstract ]
  • [ BibTeX ]
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  Herein we report a synthetic method to annulate naphthalimide moieties at different positions of a pyrene core by a cascade reaction involving palladium-mediated Suzuki-Miyaura cross-coupling and direct C-H arylation affording a new class of rylene bisimides, which we term as pseudo-rylene bisimides. The Pd-mediated reactions of peri-dibromonaphthalimide and pyrene boronic acid esters lead exclusively to six-membered ring annulation by a cascade C-C bond formation, for which a mechanistic rationale is proposed. Depending on the molecular geometry of the new pseudo-rylene bisimides, their optical properties resemble those of zethrene or terrylene bisimides, or polycyclic aromatic hydrocarbons like coronenes. The structural integrity of this new type of pseudo-rylene bisimides was confirmed by single crystal X-ray analysis.

  @article{C6QO00421K, abstract = {Herein we report a synthetic method to annulate naphthalimide moieties at different positions of a pyrene core by a cascade reaction involving palladium-mediated Suzuki-Miyaura cross-coupling and direct C-H arylation affording a new class of rylene bisimides{,} which we term as pseudo-rylene bisimides. The Pd-mediated reactions of peri-dibromonaphthalimide and pyrene boronic acid esters lead exclusively to six-membered ring annulation by a cascade C-C bond formation{,} for which a mechanistic rationale is proposed. Depending on the molecular geometry of the new pseudo-rylene bisimides{,} their optical properties resemble those of zethrene or terrylene bisimides{,} or polycyclic aromatic hydrocarbons like coronenes. The structural integrity of this new type of pseudo-rylene bisimides was confirmed by single crystal X-ray analysis.}, author = {Seifert, Sabine and Schmidt, David and Würthner, Frank}, journal = {Org. Chem. Front.}, keywords = {myown}, number = 11, pages = {1435-1442}, publisher = {The Royal Society of Chemistry}, title = {A cross-coupling-annulation cascade from peri-dibromonaphthalimide to pseudo-rylene bisimides}, volume = 3, year = 2016 }

  %0 Journal Article %1 C6QO00421K %A Seifert, Sabine %A Schmidt, David %A Würthner, Frank %D 2016 %I The Royal Society of Chemistry %J Org. Chem. Front. %N 11 %P 1435-1442 %R 10.1039/C6QO00421K %T A cross-coupling-annulation cascade from peri-dibromonaphthalimide to pseudo-rylene bisimides %U http://dx.doi.org/10.1039/C6QO00421K %V 3 %X Herein we report a synthetic method to annulate naphthalimide moieties at different positions of a pyrene core by a cascade reaction involving palladium-mediated Suzuki-Miyaura cross-coupling and direct C-H arylation affording a new class of rylene bisimides, which we term as pseudo-rylene bisimides. The Pd-mediated reactions of peri-dibromonaphthalimide and pyrene boronic acid esters lead exclusively to six-membered ring annulation by a cascade C-C bond formation, for which a mechanistic rationale is proposed. Depending on the molecular geometry of the new pseudo-rylene bisimides, their optical properties resemble those of zethrene or terrylene bisimides, or polycyclic aromatic hydrocarbons like coronenes. The structural integrity of this new type of pseudo-rylene bisimides was confirmed by single crystal X-ray analysis.
• Single-crystal field-effect transistors of a highly dipolar merocyanine dye. Liess, Andreas; Stolte, Matthias; He, Tao; Würthner, Frank. In Mater. Horiz., 3(1), pp. 72–77. 2016.
  • [ Abstract ]
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  • [ DOI ]
  The charge transport properties of a highly dipolar merocyanine dye are investigated in single-crystal field-effect transistors. The devices can reach a p-type mobility value of up to 2.34 cm2 V-1 s-1 and calculations show that the charge transport mainly occurs along the [small pi]-stacking direction of the needle-like single crystals.

  @article{C5MH00167F, abstract = {The charge transport properties of a highly dipolar merocyanine dye are investigated in single-crystal field-effect transistors. The devices can reach a p-type mobility value of up to 2.34 cm2 V-1 s-1 and calculations show that the charge transport mainly occurs along the [small pi]-stacking direction of the needle-like single crystals.}, author = {Liess, Andreas and Stolte, Matthias and He, Tao and Würthner, Frank}, journal = {Mater. Horiz.}, keywords = {myown}, number = 1, pages = {72-77}, publisher = {The Royal Society of Chemistry}, title = {Single-crystal field-effect transistors of a highly dipolar merocyanine dye}, volume = 3, year = 2016 }

  %0 Journal Article %1 C5MH00167F %A Liess, Andreas %A Stolte, Matthias %A He, Tao %A Würthner, Frank %D 2016 %I The Royal Society of Chemistry %J Mater. Horiz. %N 1 %P 72-77 %R 10.1039/C5MH00167F %T Single-crystal field-effect transistors of a highly dipolar merocyanine dye %U http://dx.doi.org/10.1039/C5MH00167F %V 3 %X The charge transport properties of a highly dipolar merocyanine dye are investigated in single-crystal field-effect transistors. The devices can reach a p-type mobility value of up to 2.34 cm2 V-1 s-1 and calculations show that the charge transport mainly occurs along the [small pi]-stacking direction of the needle-like single crystals.

• Halochromic and hydrochromic squaric acid functionalized perylene bisimide. Maeda, Takeshi; Würthner, Frank. In Chem. Commun., 51(36), pp. 7661–7664. 2015.
  • [ Abstract ]
  • [ BibTeX ]
  • [ EndNote ]
  • [ DOI ]
  The functionalization of perylene bisimide by squaric acid afforded halochromic dyes with pronounced acidity. The dye senses solvent polarity, pH and humidity by means of pronounced changes in absorption spectra and thin film color through the intramolecular charge transfer between perylene and cyclobutene cores initiated by protonation/deprotonation.

  @article{C5CC01691F, abstract = {The functionalization of perylene bisimide by squaric acid afforded halochromic dyes with pronounced acidity. The dye senses solvent polarity{,} pH and humidity by means of pronounced changes in absorption spectra and thin film color through the intramolecular charge transfer between perylene and cyclobutene cores initiated by protonation/deprotonation.}, author = {Maeda, Takeshi and Würthner, Frank}, journal = {Chem. Commun.}, keywords = {myown}, number = 36, pages = {7661-7664}, publisher = {The Royal Society of Chemistry}, title = {Halochromic and hydrochromic squaric acid functionalized perylene bisimide}, volume = 51, year = 2015 }

  %0 Journal Article %1 C5CC01691F %A Maeda, Takeshi %A Würthner, Frank %D 2015 %I The Royal Society of Chemistry %J Chem. Commun. %N 36 %P 7661-7664 %R 10.1039/C5CC01691F %T Halochromic and hydrochromic squaric acid functionalized perylene bisimide %U http://dx.doi.org/10.1039/C5CC01691F %V 51 %X The functionalization of perylene bisimide by squaric acid afforded halochromic dyes with pronounced acidity. The dye senses solvent polarity, pH and humidity by means of pronounced changes in absorption spectra and thin film color through the intramolecular charge transfer between perylene and cyclobutene cores initiated by protonation/deprotonation.
• Influence of Solid-State Packing of Dipolar Merocyanine Dyes on Transistor and Solar Cell Performances. Arjona-Esteban, Alhama; Krumrain, Julian; Liess, Andreas; Stolte, Matthias; Huang, Lizhen; Schmidt, David; Stepanenko, Vladimir; Gsänger, Marcel; Hertel, Dirk; Meerholz, Klaus; Würthner, Frank. In J. Am. Chem. Soc., 137(42), pp. 13524–13534. 2015.

  PMID: 26414767
  • [ Abstract ]
  • [ BibTeX ]
  • [ EndNote ]
  • [ DOI ]
  A series of nine dipolar merocyanine dyes has been studied as organic semiconductors in transistors and solar cells. These dyes exhibited single-crystal packing motifs with different dimensional ordering, which can be correlated to the performance of the studied devices. Hereby, the long-range ordering of the dyes in staircase-like slipped stacks with J-type excitonic coupling favors charge transport and improves solar cell performance. The different morphologies of transistor thin films and solar cell active layers were investigated by UV–vis, AFM, and XRD experiments. Selenium-containing donor–acceptor (D–A) dimethine dye 4 showed the highest hole mobility of 0.08 cm2 V–1 s–1. BHJ solar cells based on dye 4 were optimized by taking advantage of the high crystallinity of the donor material and afforded a PCE of up to 6.2\%.

  @article{doi:10.1021/jacs.5b06722, abstract = {A series of nine dipolar merocyanine dyes has been studied as organic semiconductors in transistors and solar cells. These dyes exhibited single-crystal packing motifs with different dimensional ordering, which can be correlated to the performance of the studied devices. Hereby, the long-range ordering of the dyes in staircase-like slipped stacks with J-type excitonic coupling favors charge transport and improves solar cell performance. The different morphologies of transistor thin films and solar cell active layers were investigated by UV–vis, AFM, and XRD experiments. Selenium-containing donor–acceptor (D–A) dimethine dye 4 showed the highest hole mobility of 0.08 cm2 V–1 s–1. BHJ solar cells based on dye 4 were optimized by taking advantage of the high crystallinity of the donor material and afforded a PCE of up to 6.2\%.}, author = {Arjona-Esteban, Alhama and Krumrain, Julian and Liess, Andreas and Stolte, Matthias and Huang, Lizhen and Schmidt, David and Stepanenko, Vladimir and Gsänger, Marcel and Hertel, Dirk and Meerholz, Klaus and Würthner, Frank}, journal = {J. Am. Chem. Soc.}, keywords = {myown}, note = {PMID: 26414767}, number = 42, pages = {13524-13534}, title = {Influence of Solid-State Packing of Dipolar Merocyanine Dyes on Transistor and Solar Cell Performances}, volume = 137, year = 2015 }

  %0 Journal Article %1 doi:10.1021/jacs.5b06722 %A Arjona-Esteban, Alhama %A Krumrain, Julian %A Liess, Andreas %A Stolte, Matthias %A Huang, Lizhen %A Schmidt, David %A Stepanenko, Vladimir %A Gsänger, Marcel %A Hertel, Dirk %A Meerholz, Klaus %A Würthner, Frank %D 2015 %J J. Am. Chem. Soc. %N 42 %P 13524-13534 %R 10.1021/jacs.5b06722 %T Influence of Solid-State Packing of Dipolar Merocyanine Dyes on Transistor and Solar Cell Performances %U http://dx.doi.org/10.1021/jacs.5b06722 %V 137 %X A series of nine dipolar merocyanine dyes has been studied as organic semiconductors in transistors and solar cells. These dyes exhibited single-crystal packing motifs with different dimensional ordering, which can be correlated to the performance of the studied devices. Hereby, the long-range ordering of the dyes in staircase-like slipped stacks with J-type excitonic coupling favors charge transport and improves solar cell performance. The different morphologies of transistor thin films and solar cell active layers were investigated by UV–vis, AFM, and XRD experiments. Selenium-containing donor–acceptor (D–A) dimethine dye 4 showed the highest hole mobility of 0.08 cm2 V–1 s–1. BHJ solar cells based on dye 4 were optimized by taking advantage of the high crystallinity of the donor material and afforded a PCE of up to 6.2\%.
• Sensing of Double-Stranded DNA/RNA Secondary Structures by Water Soluble Homochiral Perylene Bisimide Dyes. Gershberg, Jana; Radić Stojković, Marijana; Škugor, Marko; Tomić, Sanja; Rehm, Thomas H.; Rehm, Stefanie; Saha-Möller, Chantu R.; Piantanida, Ivo; Würthner, Frank. In Chemistry – A European Journal, 21(21), pp. 7886–7895. 2015.
  • [ Abstract ]
  • [ BibTeX ]
  • [ EndNote ]
  • [ DOI ]
  A broad series of homochiral perylene bisimide (PBI) dyes were synthesized that are appended with amino acids and cationic side chains at the imide positions. Self-assembly behavior of these ionic PBIs has been studied in aqueous media by UV/Vis spectroscopy, revealing formation of excitonically coupled H-type aggregates. The interactions of these ionic PBIs with different ds-DNA and ds-RNA have been explored by thermal denaturation, fluorimetric titration and circular dichroism (CD) experiments. These PBIs strongly stabilized ds-DNA/RNA against thermal denaturation as revealed by high melting temperatures of the formed PBI/polynucleotide complexes. Fluorimetric titrations showed that these PBIs bind to ds-DNA/RNA with high binding constants depending on the number of the positive charges in the side chains. Thus, spermine-containing PBIs with six positive charges each showed higher binding constants (logKs=9.2–9.8) than their dioxa analogues (logKs=6.5–7.9) having two positive charges each. Induced circular dichroism (ICD) of PBI assemblies created within DNA/RNA grooves was observed. These ICD profiles are strongly dependent on the steric demand of the chiral substituents of the amino acid units and the secondary structure of the DNA or RNA. The observed ICD effects can be explained by non-covalent binding of excitonically coupled PBI dimer aggregates into the minor groove of DNA and major groove of RNA which is further supported by molecular modeling studies.

  @article{CHEM:CHEM201500184, abstract = {A broad series of homochiral perylene bisimide (PBI) dyes were synthesized that are appended with amino acids and cationic side chains at the imide positions. Self-assembly behavior of these ionic PBIs has been studied in aqueous media by UV/Vis spectroscopy, revealing formation of excitonically coupled H-type aggregates. The interactions of these ionic PBIs with different ds-DNA and ds-RNA have been explored by thermal denaturation, fluorimetric titration and circular dichroism (CD) experiments. These PBIs strongly stabilized ds-DNA/RNA against thermal denaturation as revealed by high melting temperatures of the formed PBI/polynucleotide complexes. Fluorimetric titrations showed that these PBIs bind to ds-DNA/RNA with high binding constants depending on the number of the positive charges in the side chains. Thus, spermine-containing PBIs with six positive charges each showed higher binding constants (logKs=9.2–9.8) than their dioxa analogues (logKs=6.5–7.9) having two positive charges each. Induced circular dichroism (ICD) of PBI assemblies created within DNA/RNA grooves was observed. These ICD profiles are strongly dependent on the steric demand of the chiral substituents of the amino acid units and the secondary structure of the DNA or RNA. The observed ICD effects can be explained by non-covalent binding of excitonically coupled PBI dimer aggregates into the minor groove of DNA and major groove of RNA which is further supported by molecular modeling studies.}, author = {Gershberg, Jana and Radić Stojković, Marijana and Škugor, Marko and Tomić, Sanja and Rehm, Thomas H. and Rehm, Stefanie and Saha-Möller, Chantu R. and Piantanida, Ivo and Würthner, Frank}, journal = {Chemistry – A European Journal}, keywords = {myown}, number = 21, pages = {7886–7895}, publisher = {WILEY-VCH Verlag}, title = {Sensing of Double-Stranded DNA/RNA Secondary Structures by Water Soluble Homochiral Perylene Bisimide Dyes}, volume = 21, year = 2015 }

  %0 Journal Article %1 CHEM:CHEM201500184 %A Gershberg, Jana %A Radić Stojković, Marijana %A Škugor, Marko %A Tomić, Sanja %A Rehm, Thomas H. %A Rehm, Stefanie %A Saha-Möller, Chantu R. %A Piantanida, Ivo %A Würthner, Frank %D 2015 %I WILEY-VCH Verlag %J Chemistry – A European Journal %N 21 %P 7886--7895 %R 10.1002/chem.201500184 %T Sensing of Double-Stranded DNA/RNA Secondary Structures by Water Soluble Homochiral Perylene Bisimide Dyes %U http://dx.doi.org/10.1002/chem.201500184 %V 21 %X A broad series of homochiral perylene bisimide (PBI) dyes were synthesized that are appended with amino acids and cationic side chains at the imide positions. Self-assembly behavior of these ionic PBIs has been studied in aqueous media by UV/Vis spectroscopy, revealing formation of excitonically coupled H-type aggregates. The interactions of these ionic PBIs with different ds-DNA and ds-RNA have been explored by thermal denaturation, fluorimetric titration and circular dichroism (CD) experiments. These PBIs strongly stabilized ds-DNA/RNA against thermal denaturation as revealed by high melting temperatures of the formed PBI/polynucleotide complexes. Fluorimetric titrations showed that these PBIs bind to ds-DNA/RNA with high binding constants depending on the number of the positive charges in the side chains. Thus, spermine-containing PBIs with six positive charges each showed higher binding constants (logKs=9.2–9.8) than their dioxa analogues (logKs=6.5–7.9) having two positive charges each. Induced circular dichroism (ICD) of PBI assemblies created within DNA/RNA grooves was observed. These ICD profiles are strongly dependent on the steric demand of the chiral substituents of the amino acid units and the secondary structure of the DNA or RNA. The observed ICD effects can be explained by non-covalent binding of excitonically coupled PBI dimer aggregates into the minor groove of DNA and major groove of RNA which is further supported by molecular modeling studies.
• Folding-Induced Modulation of Excited-State Dynamics in an Oligophenylene–Ethynylene-Tethered Spiral Perylene Bisimide Aggregate. Son, Minjung; Fimmel, Benjamin; Dehm, Volker; Würthner, Frank; Kim, Dongho. In ChemPhysChem, 16(8), pp. 1757–1767. 2015.
  • [ Abstract ]
  • [ BibTeX ]
  • [ EndNote ]
  • [ DOI ]
  The excited-state photophysical behavior of a spiral perylene bisimide (PBI) folda-octamer (F8) tethered to an oligophenylene–ethynylene scaffold is comprehensively investigated. Solvent-dependent UV/Vis and fluorescence studies reveal that the degree of folding in this foldamer is extremely sensitive to the solvent, thus giving rise to an extended conformation in CHCl3 and a folded helical aggregate in methylcyclohexane (MCH). The exciton-deactivation dynamics are largely governed by the supramolecular structure of F8. Femtosecond transient absorption (TA) in the near-infrared region indicates a photoinduced electron-transfer process from the backbone to the PBI core in the extended conformation, whereas excitation power- and polarization-dependent TA measurements combined with computational modeling showed that excitation energy transfer between the unit PBI chromophores is the major deactivation pathway in the folded counterpart.

  @article{CPHC:CPHC201500156, abstract = {The excited-state photophysical behavior of a spiral perylene bisimide (PBI) folda-octamer (F8) tethered to an oligophenylene–ethynylene scaffold is comprehensively investigated. Solvent-dependent UV/Vis and fluorescence studies reveal that the degree of folding in this foldamer is extremely sensitive to the solvent, thus giving rise to an extended conformation in CHCl3 and a folded helical aggregate in methylcyclohexane (MCH). The exciton-deactivation dynamics are largely governed by the supramolecular structure of F8. Femtosecond transient absorption (TA) in the near-infrared region indicates a photoinduced electron-transfer process from the backbone to the PBI core in the extended conformation, whereas excitation power- and polarization-dependent TA measurements combined with computational modeling showed that excitation energy transfer between the unit PBI chromophores is the major deactivation pathway in the folded counterpart.}, author = {Son, Minjung and Fimmel, Benjamin and Dehm, Volker and Würthner, Frank and Kim, Dongho}, journal = {ChemPhysChem}, keywords = {myown}, number = 8, pages = {1757–1767}, publisher = {WILEY-VCH Verlag}, title = {Folding-Induced Modulation of Excited-State Dynamics in an Oligophenylene–Ethynylene-Tethered Spiral Perylene Bisimide Aggregate}, volume = 16, year = 2015 }

  %0 Journal Article %1 CPHC:CPHC201500156 %A Son, Minjung %A Fimmel, Benjamin %A Dehm, Volker %A Würthner, Frank %A Kim, Dongho %D 2015 %I WILEY-VCH Verlag %J ChemPhysChem %N 8 %P 1757--1767 %R 10.1002/cphc.201500156 %T Folding-Induced Modulation of Excited-State Dynamics in an Oligophenylene–Ethynylene-Tethered Spiral Perylene Bisimide Aggregate %U http://dx.doi.org/10.1002/cphc.201500156 %V 16 %X The excited-state photophysical behavior of a spiral perylene bisimide (PBI) folda-octamer (F8) tethered to an oligophenylene–ethynylene scaffold is comprehensively investigated. Solvent-dependent UV/Vis and fluorescence studies reveal that the degree of folding in this foldamer is extremely sensitive to the solvent, thus giving rise to an extended conformation in CHCl3 and a folded helical aggregate in methylcyclohexane (MCH). The exciton-deactivation dynamics are largely governed by the supramolecular structure of F8. Femtosecond transient absorption (TA) in the near-infrared region indicates a photoinduced electron-transfer process from the backbone to the PBI core in the extended conformation, whereas excitation power- and polarization-dependent TA measurements combined with computational modeling showed that excitation energy transfer between the unit PBI chromophores is the major deactivation pathway in the folded counterpart.
• Sensing of Double-Stranded DNA/RNA Secondary Structures by Water Soluble Homochiral Perylene Bisimide Dyes. Gershberg, Jana; Radić Stojković, Marijana; Škugor, Marko; Tomić, Sanja; Rehm, Thomas H.; Rehm, Stefanie; Saha-Möller, Chantu R.; Piantanida, Ivo; Würthner, Frank. In Chemistry – A European Journal, 21(21), pp. 7886–7895. 2015.
  • [ Abstract ]
  • [ BibTeX ]
  • [ EndNote ]
  • [ DOI ]
  A broad series of homochiral perylene bisimide (PBI) dyes were synthesized that are appended with amino acids and cationic side chains at the imide positions. Self-assembly behavior of these ionic PBIs has been studied in aqueous media by UV/Vis spectroscopy, revealing formation of excitonically coupled H-type aggregates. The interactions of these ionic PBIs with different ds-DNA and ds-RNA have been explored by thermal denaturation, fluorimetric titration and circular dichroism (CD) experiments. These PBIs strongly stabilized ds-DNA/RNA against thermal denaturation as revealed by high melting temperatures of the formed PBI/polynucleotide complexes. Fluorimetric titrations showed that these PBIs bind to ds-DNA/RNA with high binding constants depending on the number of the positive charges in the side chains. Thus, spermine-containing PBIs with six positive charges each showed higher binding constants (logKs=9.2–9.8) than their dioxa analogues (logKs=6.5–7.9) having two positive charges each. Induced circular dichroism (ICD) of PBI assemblies created within DNA/RNA grooves was observed. These ICD profiles are strongly dependent on the steric demand of the chiral substituents of the amino acid units and the secondary structure of the DNA or RNA. The observed ICD effects can be explained by non-covalent binding of excitonically coupled PBI dimer aggregates into the minor groove of DNA and major groove of RNA which is further supported by molecular modeling studies.

  @article{CHEM:CHEM201500184, abstract = {A broad series of homochiral perylene bisimide (PBI) dyes were synthesized that are appended with amino acids and cationic side chains at the imide positions. Self-assembly behavior of these ionic PBIs has been studied in aqueous media by UV/Vis spectroscopy, revealing formation of excitonically coupled H-type aggregates. The interactions of these ionic PBIs with different ds-DNA and ds-RNA have been explored by thermal denaturation, fluorimetric titration and circular dichroism (CD) experiments. These PBIs strongly stabilized ds-DNA/RNA against thermal denaturation as revealed by high melting temperatures of the formed PBI/polynucleotide complexes. Fluorimetric titrations showed that these PBIs bind to ds-DNA/RNA with high binding constants depending on the number of the positive charges in the side chains. Thus, spermine-containing PBIs with six positive charges each showed higher binding constants (logKs=9.2–9.8) than their dioxa analogues (logKs=6.5–7.9) having two positive charges each. Induced circular dichroism (ICD) of PBI assemblies created within DNA/RNA grooves was observed. These ICD profiles are strongly dependent on the steric demand of the chiral substituents of the amino acid units and the secondary structure of the DNA or RNA. The observed ICD effects can be explained by non-covalent binding of excitonically coupled PBI dimer aggregates into the minor groove of DNA and major groove of RNA which is further supported by molecular modeling studies.}, author = {Gershberg, Jana and Radić Stojković, Marijana and Škugor, Marko and Tomić, Sanja and Rehm, Thomas H. and Rehm, Stefanie and Saha-Möller, Chantu R. and Piantanida, Ivo and Würthner, Frank}, journal = {Chemistry – A European Journal}, keywords = {myown}, number = 21, pages = {7886–7895}, publisher = {WILEY-VCH Verlag}, title = {Sensing of Double-Stranded DNA/RNA Secondary Structures by Water Soluble Homochiral Perylene Bisimide Dyes}, volume = 21, year = 2015 }

  %0 Journal Article %1 CHEM:CHEM201500184 %A Gershberg, Jana %A Radić Stojković, Marijana %A Škugor, Marko %A Tomić, Sanja %A Rehm, Thomas H. %A Rehm, Stefanie %A Saha-Möller, Chantu R. %A Piantanida, Ivo %A Würthner, Frank %D 2015 %I WILEY-VCH Verlag %J Chemistry – A European Journal %N 21 %P 7886--7895 %R 10.1002/chem.201500184 %T Sensing of Double-Stranded DNA/RNA Secondary Structures by Water Soluble Homochiral Perylene Bisimide Dyes %U http://dx.doi.org/10.1002/chem.201500184 %V 21 %X A broad series of homochiral perylene bisimide (PBI) dyes were synthesized that are appended with amino acids and cationic side chains at the imide positions. Self-assembly behavior of these ionic PBIs has been studied in aqueous media by UV/Vis spectroscopy, revealing formation of excitonically coupled H-type aggregates. The interactions of these ionic PBIs with different ds-DNA and ds-RNA have been explored by thermal denaturation, fluorimetric titration and circular dichroism (CD) experiments. These PBIs strongly stabilized ds-DNA/RNA against thermal denaturation as revealed by high melting temperatures of the formed PBI/polynucleotide complexes. Fluorimetric titrations showed that these PBIs bind to ds-DNA/RNA with high binding constants depending on the number of the positive charges in the side chains. Thus, spermine-containing PBIs with six positive charges each showed higher binding constants (logKs=9.2–9.8) than their dioxa analogues (logKs=6.5–7.9) having two positive charges each. Induced circular dichroism (ICD) of PBI assemblies created within DNA/RNA grooves was observed. These ICD profiles are strongly dependent on the steric demand of the chiral substituents of the amino acid units and the secondary structure of the DNA or RNA. The observed ICD effects can be explained by non-covalent binding of excitonically coupled PBI dimer aggregates into the minor groove of DNA and major groove of RNA which is further supported by molecular modeling studies.
• Phenylene Ethynylene-Tethered Perylene Bisimide Folda-Dimer and Folda-Trimer: Investigations on Folding Features in Ground and Excited States. Fimmel, Benjamin; Son, Minjung; Sung, Young Mo; Grüne, Matthias; Engels, Bernd; Kim, Dongho; Würthner, Frank. In Chemistry – A European Journal, 21(2), pp. 615–630. 2015.
  • [ Abstract ]
  • [ BibTeX ]
  • [ EndNote ]
  • [ DOI ]
  In this work, we have elucidated in detail the folding properties of two perylene bisimide (PBI) foldamers composed of two and three PBI units, respectively, attached to a phenylene ethynylene backbone. The folding behaviors of these new PBI folda-dimer and trimer have been studied by solvent-dependent UV/Vis absorption and 1D and 2D NMR spectroscopy, revealing facile folding of both systems in tetrahydrofuran (THF). In CHCl3 the dimer exists in extended (unfolded) conformation, whereas partially folded conformations are observed in the trimer. Temperature-dependent 1H NMR spectroscopic studies in [D8]THF revealed intramolecular dynamic processes for both PBI foldamers due to, on the one hand, hindered rotation around CN imide bonds and, on the other hand, backbone flapping; the latter process being energetically more demanding as it was observed only at elevated temperature. The structural features of folded conformations of the dimer and trimer have been elucidated by different 2D-NMR spectroscopy (e.g., ROESY and DOSY) in [D8]THF. The energetics of folding processes for the PBI dimer and trimer have been assessed by calculations applying various methods, particularly the semiempirical PM6-DH2 and the more sophisticated B97D approach, in which relevant dispersion corrections are included. These calculations corroborate the results of NMR spectroscopic studies. Folding features in the excited states of these PBI foldamers have been characterized by using time-resolved fluorescence and transient absorption spectroscopy in THF and CHCl3, exhibiting similar solvent-dependent behavior as observed for the ground state. Interestingly, photoinduced electron transfer (PET) process from electron-donating backbone to electron-deficient PBI core for extended, but not for folded, conformations was observed, which can be explained by a fast relaxation of excited PBI stacks in the folded conformation into fluorescent excimer states.

  @article{CHEM:CHEM201405231, abstract = {In this work, we have elucidated in detail the folding properties of two perylene bisimide (PBI) foldamers composed of two and three PBI units, respectively, attached to a phenylene ethynylene backbone. The folding behaviors of these new PBI folda-dimer and trimer have been studied by solvent-dependent UV/Vis absorption and 1D and 2D NMR spectroscopy, revealing facile folding of both systems in tetrahydrofuran (THF). In CHCl3 the dimer exists in extended (unfolded) conformation, whereas partially folded conformations are observed in the trimer. Temperature-dependent 1H NMR spectroscopic studies in [D8]THF revealed intramolecular dynamic processes for both PBI foldamers due to, on the one hand, hindered rotation around CN imide bonds and, on the other hand, backbone flapping; the latter process being energetically more demanding as it was observed only at elevated temperature. The structural features of folded conformations of the dimer and trimer have been elucidated by different 2D-NMR spectroscopy (e.g., ROESY and DOSY) in [D8]THF. The energetics of folding processes for the PBI dimer and trimer have been assessed by calculations applying various methods, particularly the semiempirical PM6-DH2 and the more sophisticated B97D approach, in which relevant dispersion corrections are included. These calculations corroborate the results of NMR spectroscopic studies. Folding features in the excited states of these PBI foldamers have been characterized by using time-resolved fluorescence and transient absorption spectroscopy in THF and CHCl3, exhibiting similar solvent-dependent behavior as observed for the ground state. Interestingly, photoinduced electron transfer (PET) process from electron-donating backbone to electron-deficient PBI core for extended, but not for folded, conformations was observed, which can be explained by a fast relaxation of excited PBI stacks in the folded conformation into fluorescent excimer states.}, author = {Fimmel, Benjamin and Son, Minjung and Sung, Young Mo and Grüne, Matthias and Engels, Bernd and Kim, Dongho and Würthner, Frank}, journal = {Chemistry – A European Journal}, keywords = {myown}, number = 2, pages = {615–630}, publisher = {WILEY-VCH Verlag}, title = {Phenylene Ethynylene-Tethered Perylene Bisimide Folda-Dimer and Folda-Trimer: Investigations on Folding Features in Ground and Excited States}, volume = 21, year = 2015 }

  %0 Journal Article %1 CHEM:CHEM201405231 %A Fimmel, Benjamin %A Son, Minjung %A Sung, Young Mo %A Grüne, Matthias %A Engels, Bernd %A Kim, Dongho %A Würthner, Frank %D 2015 %I WILEY-VCH Verlag %J Chemistry – A European Journal %N 2 %P 615--630 %R 10.1002/chem.201405231 %T Phenylene Ethynylene-Tethered Perylene Bisimide Folda-Dimer and Folda-Trimer: Investigations on Folding Features in Ground and Excited States %U http://dx.doi.org/10.1002/chem.201405231 %V 21 %X In this work, we have elucidated in detail the folding properties of two perylene bisimide (PBI) foldamers composed of two and three PBI units, respectively, attached to a phenylene ethynylene backbone. The folding behaviors of these new PBI folda-dimer and trimer have been studied by solvent-dependent UV/Vis absorption and 1D and 2D NMR spectroscopy, revealing facile folding of both systems in tetrahydrofuran (THF). In CHCl3 the dimer exists in extended (unfolded) conformation, whereas partially folded conformations are observed in the trimer. Temperature-dependent 1H NMR spectroscopic studies in [D8]THF revealed intramolecular dynamic processes for both PBI foldamers due to, on the one hand, hindered rotation around CN imide bonds and, on the other hand, backbone flapping; the latter process being energetically more demanding as it was observed only at elevated temperature. The structural features of folded conformations of the dimer and trimer have been elucidated by different 2D-NMR spectroscopy (e.g., ROESY and DOSY) in [D8]THF. The energetics of folding processes for the PBI dimer and trimer have been assessed by calculations applying various methods, particularly the semiempirical PM6-DH2 and the more sophisticated B97D approach, in which relevant dispersion corrections are included. These calculations corroborate the results of NMR spectroscopic studies. Folding features in the excited states of these PBI foldamers have been characterized by using time-resolved fluorescence and transient absorption spectroscopy in THF and CHCl3, exhibiting similar solvent-dependent behavior as observed for the ground state. Interestingly, photoinduced electron transfer (PET) process from electron-donating backbone to electron-deficient PBI core for extended, but not for folded, conformations was observed, which can be explained by a fast relaxation of excited PBI stacks in the folded conformation into fluorescent excimer states.
• Folding-Induced Modulation of Excited-State Dynamics in an Oligophenylene–Ethynylene-Tethered Spiral Perylene Bisimide Aggregate. Son, Minjung; Fimmel, Benjamin; Dehm, Volker; Würthner, Frank; Kim, Dongho. In ChemPhysChem, 16(8), pp. 1757–1767. 2015.
  • [ Abstract ]
  • [ BibTeX ]
  • [ EndNote ]
  • [ DOI ]
  The excited-state photophysical behavior of a spiral perylene bisimide (PBI) folda-octamer (F8) tethered to an oligophenylene–ethynylene scaffold is comprehensively investigated. Solvent-dependent UV/Vis and fluorescence studies reveal that the degree of folding in this foldamer is extremely sensitive to the solvent, thus giving rise to an extended conformation in CHCl3 and a folded helical aggregate in methylcyclohexane (MCH). The exciton-deactivation dynamics are largely governed by the supramolecular structure of F8. Femtosecond transient absorption (TA) in the near-infrared region indicates a photoinduced electron-transfer process from the backbone to the PBI core in the extended conformation, whereas excitation power- and polarization-dependent TA measurements combined with computational modeling showed that excitation energy transfer between the unit PBI chromophores is the major deactivation pathway in the folded counterpart.

  @article{CPHC:CPHC201500156, abstract = {The excited-state photophysical behavior of a spiral perylene bisimide (PBI) folda-octamer (F8) tethered to an oligophenylene–ethynylene scaffold is comprehensively investigated. Solvent-dependent UV/Vis and fluorescence studies reveal that the degree of folding in this foldamer is extremely sensitive to the solvent, thus giving rise to an extended conformation in CHCl3 and a folded helical aggregate in methylcyclohexane (MCH). The exciton-deactivation dynamics are largely governed by the supramolecular structure of F8. Femtosecond transient absorption (TA) in the near-infrared region indicates a photoinduced electron-transfer process from the backbone to the PBI core in the extended conformation, whereas excitation power- and polarization-dependent TA measurements combined with computational modeling showed that excitation energy transfer between the unit PBI chromophores is the major deactivation pathway in the folded counterpart.}, author = {Son, Minjung and Fimmel, Benjamin and Dehm, Volker and Würthner, Frank and Kim, Dongho}, journal = {ChemPhysChem}, keywords = {myown}, number = 8, pages = {1757–1767}, publisher = {WILEY-VCH Verlag}, title = {Folding-Induced Modulation of Excited-State Dynamics in an Oligophenylene–Ethynylene-Tethered Spiral Perylene Bisimide Aggregate}, volume = 16, year = 2015 }

  %0 Journal Article %1 CPHC:CPHC201500156 %A Son, Minjung %A Fimmel, Benjamin %A Dehm, Volker %A Würthner, Frank %A Kim, Dongho %D 2015 %I WILEY-VCH Verlag %J ChemPhysChem %N 8 %P 1757--1767 %R 10.1002/cphc.201500156 %T Folding-Induced Modulation of Excited-State Dynamics in an Oligophenylene–Ethynylene-Tethered Spiral Perylene Bisimide Aggregate %U http://dx.doi.org/10.1002/cphc.201500156 %V 16 %X The excited-state photophysical behavior of a spiral perylene bisimide (PBI) folda-octamer (F8) tethered to an oligophenylene–ethynylene scaffold is comprehensively investigated. Solvent-dependent UV/Vis and fluorescence studies reveal that the degree of folding in this foldamer is extremely sensitive to the solvent, thus giving rise to an extended conformation in CHCl3 and a folded helical aggregate in methylcyclohexane (MCH). The exciton-deactivation dynamics are largely governed by the supramolecular structure of F8. Femtosecond transient absorption (TA) in the near-infrared region indicates a photoinduced electron-transfer process from the backbone to the PBI core in the extended conformation, whereas excitation power- and polarization-dependent TA measurements combined with computational modeling showed that excitation energy transfer between the unit PBI chromophores is the major deactivation pathway in the folded counterpart.
• Halochromic and hydrochromic squaric acid functionalized perylene bisimide. Maeda, Takeshi; Würthner, Frank. In Chem. Commun., 51(36), pp. 7661–7664. 2015.
  • [ Abstract ]
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  The functionalization of perylene bisimide by squaric acid afforded halochromic dyes with pronounced acidity. The dye senses solvent polarity, pH and humidity by means of pronounced changes in absorption spectra and thin film color through the intramolecular charge transfer between perylene and cyclobutene cores initiated by protonation/deprotonation.

  @article{C5CC01691F, abstract = {The functionalization of perylene bisimide by squaric acid afforded halochromic dyes with pronounced acidity. The dye senses solvent polarity{,} pH and humidity by means of pronounced changes in absorption spectra and thin film color through the intramolecular charge transfer between perylene and cyclobutene cores initiated by protonation/deprotonation.}, author = {Maeda, Takeshi and Würthner, Frank}, journal = {Chem. Commun.}, keywords = {myown}, number = 36, pages = {7661-7664}, publisher = {The Royal Society of Chemistry}, title = {Halochromic and hydrochromic squaric acid functionalized perylene bisimide}, volume = 51, year = 2015 }

  %0 Journal Article %1 C5CC01691F %A Maeda, Takeshi %A Würthner, Frank %D 2015 %I The Royal Society of Chemistry %J Chem. Commun. %N 36 %P 7661-7664 %R 10.1039/C5CC01691F %T Halochromic and hydrochromic squaric acid functionalized perylene bisimide %U http://dx.doi.org/10.1039/C5CC01691F %V 51 %X The functionalization of perylene bisimide by squaric acid afforded halochromic dyes with pronounced acidity. The dye senses solvent polarity, pH and humidity by means of pronounced changes in absorption spectra and thin film color through the intramolecular charge transfer between perylene and cyclobutene cores initiated by protonation/deprotonation.
• Subcomponent Self-Assembly of a 4 nm M4L6 Tetrahedron with ZnII Vertices and Perylene Bisimide Dye Edges. Frischmann, Peter D.; Kunz, Valentin; Stepanenko, Vladimir; Würthner, Frank. In Chemistry – A European Journal, 21(7), pp. 2766–2769. 2015.
  • [ Abstract ]
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  Formation of a tetrahedron with >4 nm perylene bisimide (PBI) dye edges and ZnII vertices in a one-pot 22 component self-assembly reaction is reported. The luminescent polyhedron equilibrates to a Zn2L3 helicate and disassembles upon dilution. Insights into the subcomponent self-assembly of extended PBI ligands help to refine design rules for constructing large photofunctional metallosupramolecular hosts.

  @article{CHEM:CHEM201405866, abstract = {Formation of a tetrahedron with >4 nm perylene bisimide (PBI) dye edges and ZnII vertices in a one-pot 22 component self-assembly reaction is reported. The luminescent polyhedron equilibrates to a Zn2L3 helicate and disassembles upon dilution. Insights into the subcomponent self-assembly of extended PBI ligands help to refine design rules for constructing large photofunctional metallosupramolecular hosts.}, author = {Frischmann, Peter D. and Kunz, Valentin and Stepanenko, Vladimir and Würthner, Frank}, journal = {Chemistry – A European Journal}, keywords = {myown}, number = 7, pages = {2766–2769}, publisher = {WILEY-VCH Verlag}, title = {Subcomponent Self-Assembly of a 4 nm M4L6 Tetrahedron with ZnII Vertices and Perylene Bisimide Dye Edges}, volume = 21, year = 2015 }

  %0 Journal Article %1 CHEM:CHEM201405866 %A Frischmann, Peter D. %A Kunz, Valentin %A Stepanenko, Vladimir %A Würthner, Frank %D 2015 %I WILEY-VCH Verlag %J Chemistry – A European Journal %N 7 %P 2766--2769 %R 10.1002/chem.201405866 %T Subcomponent Self-Assembly of a 4 nm M4L6 Tetrahedron with ZnII Vertices and Perylene Bisimide Dye Edges %U http://dx.doi.org/10.1002/chem.201405866 %V 21 %X Formation of a tetrahedron with >4 nm perylene bisimide (PBI) dye edges and ZnII vertices in a one-pot 22 component self-assembly reaction is reported. The luminescent polyhedron equilibrates to a Zn2L3 helicate and disassembles upon dilution. Insights into the subcomponent self-assembly of extended PBI ligands help to refine design rules for constructing large photofunctional metallosupramolecular hosts.
• Head-to-Tail Zig-Zag Packing of Dipolar Merocyanine Dyes Affords High-Performance Organic Thin-Film Transistors. Lv, Aifeng; Stolte, Matthias; Würthner, Frank. In Angew. Chem. Int. Ed., 54(36), pp. 10512–10515. 2015.
  • [ Abstract ]
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  Attachment of bulky substituents at both thiophene donor (D) and thiazole acceptor (A) heterocycles of a dipolar (μg=10.4 D) D-π-A merocyanine dye affords a more than 1 Å expansion of the common antiparallel supramolecular dimer motif in the solid state, enabling very close π-contacts (3.36 Å) to two other neighbor molecules on each of the two remaining π-faces. This unusual packing motif leads to three-dimensional percolation pathways for hole transport and affords thin-film transistors with mobility up to 0.64 cm2 V−1 s−1.

  @article{ANIE:ANIE201504190, abstract = {Attachment of bulky substituents at both thiophene donor (D) and thiazole acceptor (A) heterocycles of a dipolar (μg=10.4 D) D-π-A merocyanine dye affords a more than 1 Å expansion of the common antiparallel supramolecular dimer motif in the solid state, enabling very close π-contacts (3.36 Å) to two other neighbor molecules on each of the two remaining π-faces. This unusual packing motif leads to three-dimensional percolation pathways for hole transport and affords thin-film transistors with mobility up to 0.64 cm2 V−1 s−1.}, author = {Lv, Aifeng and Stolte, Matthias and Würthner, Frank}, journal = {Angew. Chem. Int. Ed.}, keywords = {myown}, number = 36, pages = {10512–10515}, publisher = {WILEY-VCH Verlag}, title = {Head-to-Tail Zig-Zag Packing of Dipolar Merocyanine Dyes Affords High-Performance Organic Thin-Film Transistors}, volume = 54, year = 2015 }

  %0 Journal Article %1 ANIE:ANIE201504190 %A Lv, Aifeng %A Stolte, Matthias %A Würthner, Frank %D 2015 %I WILEY-VCH Verlag %J Angew. Chem. Int. Ed. %N 36 %P 10512--10515 %R 10.1002/anie.201504190 %T Head-to-Tail Zig-Zag Packing of Dipolar Merocyanine Dyes Affords High-Performance Organic Thin-Film Transistors %U http://dx.doi.org/10.1002/anie.201504190 %V 54 %X Attachment of bulky substituents at both thiophene donor (D) and thiazole acceptor (A) heterocycles of a dipolar (μg=10.4 D) D-π-A merocyanine dye affords a more than 1 Å expansion of the common antiparallel supramolecular dimer motif in the solid state, enabling very close π-contacts (3.36 Å) to two other neighbor molecules on each of the two remaining π-faces. This unusual packing motif leads to three-dimensional percolation pathways for hole transport and affords thin-film transistors with mobility up to 0.64 cm2 V−1 s−1.
• Photoconductive Cathode Interlayer for Highly Efficient Inverted Polymer Solar Cells. Nian, Li; Zhang, Wenqiang; Zhu, Na; Liu, Linlin; Xie, Zengqi; Wu, Hongbin; Würthner, Frank; Ma, Yuguang. In J. Am. Chem. Soc., 137(22), pp. 6995–6998. 2015.

  PMID: 26016386
  • [ Abstract ]
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  A highly photoconductive cathode interlayer was achieved by doping a 1 wt \% light absorber, such as perylene bisimide, into a ZnO thin film, which absorbs a very small amount of light but shows highly increased conductivity of 4.50 × 10–3 S/m under sunlight. Photovoltaic devices based on this kind of photoactive cathode interlayer exhibit significantly improved device performance, which is rather insensitive to the thickness of the cathode interlayer over a broad range. Moreover, a power conversion efficiency as high as 10.5\% was obtained by incorporation of our photoconductive cathode interlayer with the PTB7-Th:PC71BM active layer, which is one of the best results for single-junction polymer solar cells.

  @article{doi:10.1021/jacs.5b02168, abstract = {A highly photoconductive cathode interlayer was achieved by doping a 1 wt \% light absorber, such as perylene bisimide, into a ZnO thin film, which absorbs a very small amount of light but shows highly increased conductivity of 4.50 × 10–3 S/m under sunlight. Photovoltaic devices based on this kind of photoactive cathode interlayer exhibit significantly improved device performance, which is rather insensitive to the thickness of the cathode interlayer over a broad range. Moreover, a power conversion efficiency as high as 10.5\% was obtained by incorporation of our photoconductive cathode interlayer with the PTB7-Th:PC71BM active layer, which is one of the best results for single-junction polymer solar cells.}, author = {Nian, Li and Zhang, Wenqiang and Zhu, Na and Liu, Linlin and Xie, Zengqi and Wu, Hongbin and Würthner, Frank and Ma, Yuguang}, journal = {J. Am. Chem. Soc.}, keywords = {myown}, note = {PMID: 26016386}, number = 22, pages = {6995-6998}, title = {Photoconductive Cathode Interlayer for Highly Efficient Inverted Polymer Solar Cells}, volume = 137, year = 2015 }

  %0 Journal Article %1 doi:10.1021/jacs.5b02168 %A Nian, Li %A Zhang, Wenqiang %A Zhu, Na %A Liu, Linlin %A Xie, Zengqi %A Wu, Hongbin %A Würthner, Frank %A Ma, Yuguang %D 2015 %J J. Am. Chem. Soc. %N 22 %P 6995-6998 %R 10.1021/jacs.5b02168 %T Photoconductive Cathode Interlayer for Highly Efficient Inverted Polymer Solar Cells %U http://dx.doi.org/10.1021/jacs.5b02168 %V 137 %X A highly photoconductive cathode interlayer was achieved by doping a 1 wt \% light absorber, such as perylene bisimide, into a ZnO thin film, which absorbs a very small amount of light but shows highly increased conductivity of 4.50 × 10–3 S/m under sunlight. Photovoltaic devices based on this kind of photoactive cathode interlayer exhibit significantly improved device performance, which is rather insensitive to the thickness of the cathode interlayer over a broad range. Moreover, a power conversion efficiency as high as 10.5\% was obtained by incorporation of our photoconductive cathode interlayer with the PTB7-Th:PC71BM active layer, which is one of the best results for single-junction polymer solar cells.
• A Perylene Bisimide Cyclophane as a “Turn-On” and “Turn-Off” Fluorescence Probe. Spenst, Peter; Würthner, Frank. In Angew. Chem. Int. Ed., 54(35), pp. 10165–10168. 2015.
  • [ Abstract ]
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  A rigid, covalently linked perylene-3,4:9,10-tetracarboxylic acid bisimide (PBI) cyclophane was synthesized by imidization of a bay-substituted perylene bisanhydride with p-xylylenediamine. The interchromophoric distance of approximately 6.5 Å establishes an ideal rigid cavity for the encapsulation of large aromatic compounds such as perylene and anthracene with binding constants up to 4.6×104 M−1 (in CHCl3). For electron-poor guest molecules, the complexation process is accompanied by a significantly increased fluorescence, whereas the emission intensity is dramatically quenched by more electron-rich guests because of the formation of charge-transfer complexes. Furthermore, the influence of the PBI core twist on the binding constant results in a remarkable selectivity towards more flexible aromatic guest molecules.

  @article{ANIE:ANIE201503542, abstract = {A rigid, covalently linked perylene-3,4:9,10-tetracarboxylic acid bisimide (PBI) cyclophane was synthesized by imidization of a bay-substituted perylene bisanhydride with p-xylylenediamine. The interchromophoric distance of approximately 6.5 Å establishes an ideal rigid cavity for the encapsulation of large aromatic compounds such as perylene and anthracene with binding constants up to 4.6×104 M−1 (in CHCl3). For electron-poor guest molecules, the complexation process is accompanied by a significantly increased fluorescence, whereas the emission intensity is dramatically quenched by more electron-rich guests because of the formation of charge-transfer complexes. Furthermore, the influence of the PBI core twist on the binding constant results in a remarkable selectivity towards more flexible aromatic guest molecules.}, author = {Spenst, Peter and Würthner, Frank}, journal = {Angew. Chem. Int. Ed.}, keywords = {probes}, number = 35, pages = {10165–10168}, publisher = {WILEY-VCH Verlag}, title = {A Perylene Bisimide Cyclophane as a “Turn-On” and “Turn-Off” Fluorescence Probe}, volume = 54, year = 2015 }

  %0 Journal Article %1 ANIE:ANIE201503542 %A Spenst, Peter %A Würthner, Frank %D 2015 %I WILEY-VCH Verlag %J Angew. Chem. Int. Ed. %N 35 %P 10165--10168 %R 10.1002/anie.201503542 %T A Perylene Bisimide Cyclophane as a “Turn-On” and “Turn-Off” Fluorescence Probe %U http://dx.doi.org/10.1002/anie.201503542 %V 54 %X A rigid, covalently linked perylene-3,4:9,10-tetracarboxylic acid bisimide (PBI) cyclophane was synthesized by imidization of a bay-substituted perylene bisanhydride with p-xylylenediamine. The interchromophoric distance of approximately 6.5 Å establishes an ideal rigid cavity for the encapsulation of large aromatic compounds such as perylene and anthracene with binding constants up to 4.6×104 M−1 (in CHCl3). For electron-poor guest molecules, the complexation process is accompanied by a significantly increased fluorescence, whereas the emission intensity is dramatically quenched by more electron-rich guests because of the formation of charge-transfer complexes. Furthermore, the influence of the PBI core twist on the binding constant results in a remarkable selectivity towards more flexible aromatic guest molecules.
• Phenylene Ethynylene-Tethered Perylene Bisimide Folda-Dimer and Folda-Trimer: Investigations on Folding Features in Ground and Excited States. Fimmel, Benjamin; Son, Minjung; Sung, Young Mo; Grüne, Matthias; Engels, Bernd; Kim, Dongho; Würthner, Frank. In Chemistry – A European Journal, 21(2), pp. 615–630. 2015.
  • [ Abstract ]
  • [ BibTeX ]
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  In this work, we have elucidated in detail the folding properties of two perylene bisimide (PBI) foldamers composed of two and three PBI units, respectively, attached to a phenylene ethynylene backbone. The folding behaviors of these new PBI folda-dimer and trimer have been studied by solvent-dependent UV/Vis absorption and 1D and 2D NMR spectroscopy, revealing facile folding of both systems in tetrahydrofuran (THF). In CHCl3 the dimer exists in extended (unfolded) conformation, whereas partially folded conformations are observed in the trimer. Temperature-dependent 1H NMR spectroscopic studies in [D8]THF revealed intramolecular dynamic processes for both PBI foldamers due to, on the one hand, hindered rotation around CN imide bonds and, on the other hand, backbone flapping; the latter process being energetically more demanding as it was observed only at elevated temperature. The structural features of folded conformations of the dimer and trimer have been elucidated by different 2D-NMR spectroscopy (e.g., ROESY and DOSY) in [D8]THF. The energetics of folding processes for the PBI dimer and trimer have been assessed by calculations applying various methods, particularly the semiempirical PM6-DH2 and the more sophisticated B97D approach, in which relevant dispersion corrections are included. These calculations corroborate the results of NMR spectroscopic studies. Folding features in the excited states of these PBI foldamers have been characterized by using time-resolved fluorescence and transient absorption spectroscopy in THF and CHCl3, exhibiting similar solvent-dependent behavior as observed for the ground state. Interestingly, photoinduced electron transfer (PET) process from electron-donating backbone to electron-deficient PBI core for extended, but not for folded, conformations was observed, which can be explained by a fast relaxation of excited PBI stacks in the folded conformation into fluorescent excimer states.

  @article{CHEM:CHEM201405231, abstract = {In this work, we have elucidated in detail the folding properties of two perylene bisimide (PBI) foldamers composed of two and three PBI units, respectively, attached to a phenylene ethynylene backbone. The folding behaviors of these new PBI folda-dimer and trimer have been studied by solvent-dependent UV/Vis absorption and 1D and 2D NMR spectroscopy, revealing facile folding of both systems in tetrahydrofuran (THF). In CHCl3 the dimer exists in extended (unfolded) conformation, whereas partially folded conformations are observed in the trimer. Temperature-dependent 1H NMR spectroscopic studies in [D8]THF revealed intramolecular dynamic processes for both PBI foldamers due to, on the one hand, hindered rotation around CN imide bonds and, on the other hand, backbone flapping; the latter process being energetically more demanding as it was observed only at elevated temperature. The structural features of folded conformations of the dimer and trimer have been elucidated by different 2D-NMR spectroscopy (e.g., ROESY and DOSY) in [D8]THF. The energetics of folding processes for the PBI dimer and trimer have been assessed by calculations applying various methods, particularly the semiempirical PM6-DH2 and the more sophisticated B97D approach, in which relevant dispersion corrections are included. These calculations corroborate the results of NMR spectroscopic studies. Folding features in the excited states of these PBI foldamers have been characterized by using time-resolved fluorescence and transient absorption spectroscopy in THF and CHCl3, exhibiting similar solvent-dependent behavior as observed for the ground state. Interestingly, photoinduced electron transfer (PET) process from electron-donating backbone to electron-deficient PBI core for extended, but not for folded, conformations was observed, which can be explained by a fast relaxation of excited PBI stacks in the folded conformation into fluorescent excimer states.}, author = {Fimmel, Benjamin and Son, Minjung and Sung, Young Mo and Grüne, Matthias and Engels, Bernd and Kim, Dongho and Würthner, Frank}, journal = {Chemistry – A European Journal}, keywords = {myown}, number = 2, pages = {615–630}, publisher = {WILEY-VCH Verlag}, title = {Phenylene Ethynylene-Tethered Perylene Bisimide Folda-Dimer and Folda-Trimer: Investigations on Folding Features in Ground and Excited States}, volume = 21, year = 2015 }

  %0 Journal Article %1 CHEM:CHEM201405231 %A Fimmel, Benjamin %A Son, Minjung %A Sung, Young Mo %A Grüne, Matthias %A Engels, Bernd %A Kim, Dongho %A Würthner, Frank %D 2015 %I WILEY-VCH Verlag %J Chemistry – A European Journal %N 2 %P 615--630 %R 10.1002/chem.201405231 %T Phenylene Ethynylene-Tethered Perylene Bisimide Folda-Dimer and Folda-Trimer: Investigations on Folding Features in Ground and Excited States %U http://dx.doi.org/10.1002/chem.201405231 %V 21 %X In this work, we have elucidated in detail the folding properties of two perylene bisimide (PBI) foldamers composed of two and three PBI units, respectively, attached to a phenylene ethynylene backbone. The folding behaviors of these new PBI folda-dimer and trimer have been studied by solvent-dependent UV/Vis absorption and 1D and 2D NMR spectroscopy, revealing facile folding of both systems in tetrahydrofuran (THF). In CHCl3 the dimer exists in extended (unfolded) conformation, whereas partially folded conformations are observed in the trimer. Temperature-dependent 1H NMR spectroscopic studies in [D8]THF revealed intramolecular dynamic processes for both PBI foldamers due to, on the one hand, hindered rotation around CN imide bonds and, on the other hand, backbone flapping; the latter process being energetically more demanding as it was observed only at elevated temperature. The structural features of folded conformations of the dimer and trimer have been elucidated by different 2D-NMR spectroscopy (e.g., ROESY and DOSY) in [D8]THF. The energetics of folding processes for the PBI dimer and trimer have been assessed by calculations applying various methods, particularly the semiempirical PM6-DH2 and the more sophisticated B97D approach, in which relevant dispersion corrections are included. These calculations corroborate the results of NMR spectroscopic studies. Folding features in the excited states of these PBI foldamers have been characterized by using time-resolved fluorescence and transient absorption spectroscopy in THF and CHCl3, exhibiting similar solvent-dependent behavior as observed for the ground state. Interestingly, photoinduced electron transfer (PET) process from electron-donating backbone to electron-deficient PBI core for extended, but not for folded, conformations was observed, which can be explained by a fast relaxation of excited PBI stacks in the folded conformation into fluorescent excimer states.
• Combination of Cyanine Behaviour and Giant Hyperpolarisability in Novel Merocyanine Dyes: Beyond the Bond Length Alternation (BLA) Paradigm. Parthasarathy, Venkatakrishnan; Pandey, Ravindra; Stolte, Matthias; Ghosh, Sampa; Castet, Frédéric; Würthner, Frank; Das, Puspendu Kumar; Blanchard-Desce, Mireille. In Chemistry – A European Journal, 21(40), pp. 14211–14217. 2015.
  • [ Abstract ]
  • [ BibTeX ]
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  Merocyanine dyes that exhibit antithetic cyanine-like behaviour and giant first-order hyperpolarisability (β) values have been designed. These cyanine-type dyes open up an intriguing route towards molecular-based electro-optic materials as well as new second-harmonic generation dyes for imaging.

  @article{CHEM:CHEM201501800, abstract = {Merocyanine dyes that exhibit antithetic cyanine-like behaviour and giant first-order hyperpolarisability (β) values have been designed. These cyanine-type dyes open up an intriguing route towards molecular-based electro-optic materials as well as new second-harmonic generation dyes for imaging.}, author = {Parthasarathy, Venkatakrishnan and Pandey, Ravindra and Stolte, Matthias and Ghosh, Sampa and Castet, Frédéric and Würthner, Frank and Das, Puspendu Kumar and Blanchard-Desce, Mireille}, journal = {Chemistry – A European Journal}, keywords = {myown}, number = 40, pages = {14211–14217}, publisher = {WILEY-VCH Verlag}, title = {Combination of Cyanine Behaviour and Giant Hyperpolarisability in Novel Merocyanine Dyes: Beyond the Bond Length Alternation (BLA) Paradigm}, volume = 21, year = 2015 }

  %0 Journal Article %1 CHEM:CHEM201501800 %A Parthasarathy, Venkatakrishnan %A Pandey, Ravindra %A Stolte, Matthias %A Ghosh, Sampa %A Castet, Frédéric %A Würthner, Frank %A Das, Puspendu Kumar %A Blanchard-Desce, Mireille %D 2015 %I WILEY-VCH Verlag %J Chemistry – A European Journal %N 40 %P 14211--14217 %R 10.1002/chem.201501800 %T Combination of Cyanine Behaviour and Giant Hyperpolarisability in Novel Merocyanine Dyes: Beyond the Bond Length Alternation (BLA) Paradigm %U http://dx.doi.org/10.1002/chem.201501800 %V 21 %X Merocyanine dyes that exhibit antithetic cyanine-like behaviour and giant first-order hyperpolarisability (β) values have been designed. These cyanine-type dyes open up an intriguing route towards molecular-based electro-optic materials as well as new second-harmonic generation dyes for imaging.
• Mechanism of Self-Assembly Process and Seeded Supramolecular Polymerization of Perylene Bisimide Organogelator. Ogi, Soichiro; Stepanenko, Vladimir; Sugiyasu, Kazunori; Takeuchi, Masayuki; Würthner, Frank. In J. Am. Chem. Soc., 137(9), pp. 3300–3307. 2015.

  PMID: 25689054
  • [ Abstract ]
  • [ BibTeX ]
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  The mechanism of supramolecular polymerization has been elucidated for an archetype organogelator molecule composed of a perylene bisimide aromatic scaffold and two amide substituents. This molecule self-assembles into elongated one-dimensional nanofibers through a cooperative nucleation–growth process. Thermodynamic and kinetic analyses have been applied to discover conditions (temperature, solvent, concentration) where the spontaneous nucleation can be retarded by trapping of the monomers in an inactive conformation, leading to lag times up to more than 1 h. The unique kinetics in the nucleation process was confirmed as a thermal hysteresis in a cycle of assembly and disassembly processes. Under appropriate conditions within the hysteresis loop, addition of preassembled nanofiber seeds leads to seeded polymerization from the termini of the seeds in a living supramolecular polymerization process. These results demonstrate that seeded polymerizations are not limited to special situations where off-pathway aggregates sequester the monomeric reactant species but may be applicable to a large number of known and to be developed molecules from the large family of molecules that self-assemble into one-dimensional nanofibrous structures. Generalizing from the mechanistic insight into our seeded polymerization, we assert that a cooperative nucleation–growth supramolecular polymerization accompanied by thermal hysteresis can be controlled in a living manner.

  @article{doi:10.1021/ja511952c, abstract = {The mechanism of supramolecular polymerization has been elucidated for an archetype organogelator molecule composed of a perylene bisimide aromatic scaffold and two amide substituents. This molecule self-assembles into elongated one-dimensional nanofibers through a cooperative nucleation–growth process. Thermodynamic and kinetic analyses have been applied to discover conditions (temperature, solvent, concentration) where the spontaneous nucleation can be retarded by trapping of the monomers in an inactive conformation, leading to lag times up to more than 1 h. The unique kinetics in the nucleation process was confirmed as a thermal hysteresis in a cycle of assembly and disassembly processes. Under appropriate conditions within the hysteresis loop, addition of preassembled nanofiber seeds leads to seeded polymerization from the termini of the seeds in a living supramolecular polymerization process. These results demonstrate that seeded polymerizations are not limited to special situations where off-pathway aggregates sequester the monomeric reactant species but may be applicable to a large number of known and to be developed molecules from the large family of molecules that self-assemble into one-dimensional nanofibrous structures. Generalizing from the mechanistic insight into our seeded polymerization, we assert that a cooperative nucleation–growth supramolecular polymerization accompanied by thermal hysteresis can be controlled in a living manner.}, author = {Ogi, Soichiro and Stepanenko, Vladimir and Sugiyasu, Kazunori and Takeuchi, Masayuki and Würthner, Frank}, journal = {J. Am. Chem. Soc.}, keywords = {myown}, note = {PMID: 25689054}, number = 9, pages = {3300-3307}, title = {Mechanism of Self-Assembly Process and Seeded Supramolecular Polymerization of Perylene Bisimide Organogelator}, volume = 137, year = 2015 }

  %0 Journal Article %1 doi:10.1021/ja511952c %A Ogi, Soichiro %A Stepanenko, Vladimir %A Sugiyasu, Kazunori %A Takeuchi, Masayuki %A Würthner, Frank %D 2015 %J J. Am. Chem. Soc. %N 9 %P 3300-3307 %R 10.1021/ja511952c %T Mechanism of Self-Assembly Process and Seeded Supramolecular Polymerization of Perylene Bisimide Organogelator %U http://dx.doi.org/10.1021/ja511952c %V 137 %X The mechanism of supramolecular polymerization has been elucidated for an archetype organogelator molecule composed of a perylene bisimide aromatic scaffold and two amide substituents. This molecule self-assembles into elongated one-dimensional nanofibers through a cooperative nucleation–growth process. Thermodynamic and kinetic analyses have been applied to discover conditions (temperature, solvent, concentration) where the spontaneous nucleation can be retarded by trapping of the monomers in an inactive conformation, leading to lag times up to more than 1 h. The unique kinetics in the nucleation process was confirmed as a thermal hysteresis in a cycle of assembly and disassembly processes. Under appropriate conditions within the hysteresis loop, addition of preassembled nanofiber seeds leads to seeded polymerization from the termini of the seeds in a living supramolecular polymerization process. These results demonstrate that seeded polymerizations are not limited to special situations where off-pathway aggregates sequester the monomeric reactant species but may be applicable to a large number of known and to be developed molecules from the large family of molecules that self-assemble into one-dimensional nanofibrous structures. Generalizing from the mechanistic insight into our seeded polymerization, we assert that a cooperative nucleation–growth supramolecular polymerization accompanied by thermal hysteresis can be controlled in a living manner.
• Perylene Bisimide Radicals and Biradicals: Synthesis and Molecular Properties. Schmidt, David; Son, Minjung; Lim, Jong Min; Lin, Mei-Jin; Krummenacher, Ivo; Braunschweig, Holger; Kim, Dongho; Würthner, Frank. In Angew. Chem. Int. Ed., 54(47), pp. 13980–13984. 2015.
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  Unprecedented neutral perylene-3,4:9,10-tetracarboxylic acid bisimide (PBI) radicals and biradicals were synthesized by facile chemical oxidation of 4-hydroxyaryl-substituted PBIs. Subsequent characterization by optical and magnetic spectroscopic techniques, as well as quantum chemical calculations, revealed an open-shell singlet biradical ground state for the PBI biradical OS-2.. (〈s2〉=1.2191) with a relatively small singlet–triplet energy gap of 0.041 eV and a large singlet biradical character of y=0.72.

  @article{ANIE:ANIE201507039, abstract = {Unprecedented neutral perylene-3,4:9,10-tetracarboxylic acid bisimide (PBI) radicals and biradicals were synthesized by facile chemical oxidation of 4-hydroxyaryl-substituted PBIs. Subsequent characterization by optical and magnetic spectroscopic techniques, as well as quantum chemical calculations, revealed an open-shell singlet biradical ground state for the PBI biradical OS-2.. (〈s2〉=1.2191) with a relatively small singlet–triplet energy gap of 0.041 eV and a large singlet biradical character of y=0.72.}, author = {Schmidt, David and Son, Minjung and Lim, Jong Min and Lin, Mei-Jin and Krummenacher, Ivo and Braunschweig, Holger and Kim, Dongho and Würthner, Frank}, journal = {Angew. Chem. Int. Ed.}, keywords = {myown}, number = 47, pages = {13980–13984}, publisher = {WILEY-VCH Verlag}, title = {Perylene Bisimide Radicals and Biradicals: Synthesis and Molecular Properties}, volume = 54, year = 2015 }

  %0 Journal Article %1 ANIE:ANIE201507039 %A Schmidt, David %A Son, Minjung %A Lim, Jong Min %A Lin, Mei-Jin %A Krummenacher, Ivo %A Braunschweig, Holger %A Kim, Dongho %A Würthner, Frank %D 2015 %I WILEY-VCH Verlag %J Angew. Chem. Int. Ed. %N 47 %P 13980--13984 %R 10.1002/anie.201507039 %T Perylene Bisimide Radicals and Biradicals: Synthesis and Molecular Properties %U http://dx.doi.org/10.1002/anie.201507039 %V 54 %X Unprecedented neutral perylene-3,4:9,10-tetracarboxylic acid bisimide (PBI) radicals and biradicals were synthesized by facile chemical oxidation of 4-hydroxyaryl-substituted PBIs. Subsequent characterization by optical and magnetic spectroscopic techniques, as well as quantum chemical calculations, revealed an open-shell singlet biradical ground state for the PBI biradical OS-2.. (〈s2〉=1.2191) with a relatively small singlet–triplet energy gap of 0.041 eV and a large singlet biradical character of y=0.72.
• Self-assembled perylene bisimide J-aggregates as promising cathode modifiers for highly efficient inverted polymer solar cells. Xie, Zengqi; Xiao, Biao; He, Zhicai; Zhang, Wenqiang; Wu, Xiaoyan; Wu, Hongbin; Würthner, Frank; Wang, Chao; Xie, Fangyan; Liu, Linlin; Ma, Yuguang; Wong, Wai-Yeung; Cao, Yong. In Mater. Horiz., 2(5), pp. 514–518. 2015.
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  Solvent-dependent self-assemblies of perylene bisimide (PBI) are applied as cathode modification layers in inverted polymer solar cells (i-PSCs) to afford a power conversion efficiency (PCE) as high as 9.11%. The very high device performance clearly indicates that n-type perylene bisimide based supramolecular assemblies are most promising interfacial materials for highly efficient i-PSCs.

  @article{C5MH00056D, abstract = {Solvent-dependent self-assemblies of perylene bisimide (PBI) are applied as cathode modification layers in inverted polymer solar cells (i-PSCs) to afford a power conversion efficiency (PCE) as high as 9.11%. The very high device performance clearly indicates that n-type perylene bisimide based supramolecular assemblies are most promising interfacial materials for highly efficient i-PSCs.}, author = {Xie, Zengqi and Xiao, Biao and He, Zhicai and Zhang, Wenqiang and Wu, Xiaoyan and Wu, Hongbin and Würthner, Frank and Wang, Chao and Xie, Fangyan and Liu, Linlin and Ma, Yuguang and Wong, Wai-Yeung and Cao, Yong}, journal = {Mater. Horiz.}, keywords = {myown}, number = 5, pages = {514-518}, publisher = {The Royal Society of Chemistry}, title = {Self-assembled perylene bisimide J-aggregates as promising cathode modifiers for highly efficient inverted polymer solar cells}, volume = 2, year = 2015 }

  %0 Journal Article %1 C5MH00056D %A Xie, Zengqi %A Xiao, Biao %A He, Zhicai %A Zhang, Wenqiang %A Wu, Xiaoyan %A Wu, Hongbin %A Würthner, Frank %A Wang, Chao %A Xie, Fangyan %A Liu, Linlin %A Ma, Yuguang %A Wong, Wai-Yeung %A Cao, Yong %D 2015 %I The Royal Society of Chemistry %J Mater. Horiz. %N 5 %P 514-518 %R 10.1039/C5MH00056D %T Self-assembled perylene bisimide J-aggregates as promising cathode modifiers for highly efficient inverted polymer solar cells %U http://dx.doi.org/10.1039/C5MH00056D %V 2 %X Solvent-dependent self-assemblies of perylene bisimide (PBI) are applied as cathode modification layers in inverted polymer solar cells (i-PSCs) to afford a power conversion efficiency (PCE) as high as 9.11%. The very high device performance clearly indicates that n-type perylene bisimide based supramolecular assemblies are most promising interfacial materials for highly efficient i-PSCs.
• In-situ modification of PEDOT:PSS work function using alkyl alcohols as secondary processing solvents and their impact on merocyanine based bulk heterojunction solar cells. Lenze, Martin R.; Kronenberg, Nils M.; Würthner, Frank; Meerholz, Klaus. In Organic Electronics, 21(Supplement C), pp. 171–176. 2015.
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  Abstract The influence of a series of alkyl alcohols on the work function of PEDOT:PSS thin films is systematically investigated by Kelvin probe measurements. We show that the PEDOT:PSS work function can be increased stepwise from 5.2eV for pristine PEDOT:PSS to 5.61eV using either alcohols with different alkyl chain length or varying the amount of alcohol in mixtures with chlorobenzene. Moreover, we demonstrate the effect of work function modification on merocyanine based bulk heterojunction solar cells, resulting in improved values for the open-circuit voltage comparable to those obtained with high work function MoO3. Thus, the processing method presented herein can potentially serve as a simple, alternative route to adjustable and high work function electrodes while maintaining processability from solution.

  @article{LENZE2015171, abstract = {Abstract The influence of a series of alkyl alcohols on the work function of PEDOT:PSS thin films is systematically investigated by Kelvin probe measurements. We show that the PEDOT:PSS work function can be increased stepwise from 5.2eV for pristine PEDOT:PSS to 5.61eV using either alcohols with different alkyl chain length or varying the amount of alcohol in mixtures with chlorobenzene. Moreover, we demonstrate the effect of work function modification on merocyanine based bulk heterojunction solar cells, resulting in improved values for the open-circuit voltage comparable to those obtained with high work function MoO3. Thus, the processing method presented herein can potentially serve as a simple, alternative route to adjustable and high work function electrodes while maintaining processability from solution.}, author = {Lenze, Martin R. and Kronenberg, Nils M. and Würthner, Frank and Meerholz, Klaus}, journal = {Organic Electronics}, keywords = {Merocyanines}, number = {Supplement C}, pages = {171 - 176}, title = {In-situ modification of PEDOT:PSS work function using alkyl alcohols as secondary processing solvents and their impact on merocyanine based bulk heterojunction solar cells}, volume = 21, year = 2015 }

  %0 Journal Article %1 LENZE2015171 %A Lenze, Martin R. %A Kronenberg, Nils M. %A Würthner, Frank %A Meerholz, Klaus %D 2015 %J Organic Electronics %N Supplement C %P 171 - 176 %R https://doi.org/10.1016/j.orgel.2015.03.008 %T In-situ modification of PEDOT:PSS work function using alkyl alcohols as secondary processing solvents and their impact on merocyanine based bulk heterojunction solar cells %U http://www.sciencedirect.com/science/article/pii/S1566119915000993 %V 21 %X Abstract The influence of a series of alkyl alcohols on the work function of PEDOT:PSS thin films is systematically investigated by Kelvin probe measurements. We show that the PEDOT:PSS work function can be increased stepwise from 5.2eV for pristine PEDOT:PSS to 5.61eV using either alcohols with different alkyl chain length or varying the amount of alcohol in mixtures with chlorobenzene. Moreover, we demonstrate the effect of work function modification on merocyanine based bulk heterojunction solar cells, resulting in improved values for the open-circuit voltage comparable to those obtained with high work function MoO3. Thus, the processing method presented herein can potentially serve as a simple, alternative route to adjustable and high work function electrodes while maintaining processability from solution.
• Concentration-dependent rhombitrihexagonal tiling patterns at the liquid/solid interface. Stepanenko, Vladimir; Kandanelli, Ramesh; Uemura, Shinobu; Würthner, Frank; Fernandez, Gustavo. In Chem. Sci., 6(10), pp. 5853–5858. 2015.
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  We report STM investigations on a linear oligophenyleneethylene (OPE)-based self-assembling Pd(ii) complex 1 that forms highly-ordered concentration dependent patterns on HOPG. At high concentration, 2D lamellar structures are observed whereas the dilution of the system below a critical concentration leads to the formation of visually attractive rhombitrihexagonal Archimedean tiling arrangements featuring three different kinds of polygons: triangles, hexagons and rhombi. The key participation of the Cl ligands attached to the Pd(ii) centre in multiple C-H[three dots, centered]Cl interactions was demonstrated by comparing the patterns of 1 with those of an analogous non-metallic system 2.

  @article{C5SC00811E, abstract = {We report STM investigations on a linear oligophenyleneethylene (OPE)-based self-assembling Pd(ii) complex 1 that forms highly-ordered concentration dependent patterns on HOPG. At high concentration{,} 2D lamellar structures are observed whereas the dilution of the system below a critical concentration leads to the formation of visually attractive rhombitrihexagonal Archimedean tiling arrangements featuring three different kinds of polygons: triangles{,} hexagons and rhombi. The key participation of the Cl ligands attached to the Pd(ii) centre in multiple C-H[three dots{,} centered]Cl interactions was demonstrated by comparing the patterns of 1 with those of an analogous non-metallic system 2.}, author = {Stepanenko, Vladimir and Kandanelli, Ramesh and Uemura, Shinobu and Würthner, Frank and Fernandez, Gustavo}, journal = {Chem. Sci.}, keywords = {myown}, number = 10, pages = {5853-5858}, publisher = {The Royal Society of Chemistry}, title = {Concentration-dependent rhombitrihexagonal tiling patterns at the liquid/solid interface}, volume = 6, year = 2015 }

  %0 Journal Article %1 C5SC00811E %A Stepanenko, Vladimir %A Kandanelli, Ramesh %A Uemura, Shinobu %A Würthner, Frank %A Fernandez, Gustavo %D 2015 %I The Royal Society of Chemistry %J Chem. Sci. %N 10 %P 5853-5858 %R 10.1039/C5SC00811E %T Concentration-dependent rhombitrihexagonal tiling patterns at the liquid/solid interface %U http://dx.doi.org/10.1039/C5SC00811E %V 6 %X We report STM investigations on a linear oligophenyleneethylene (OPE)-based self-assembling Pd(ii) complex 1 that forms highly-ordered concentration dependent patterns on HOPG. At high concentration, 2D lamellar structures are observed whereas the dilution of the system below a critical concentration leads to the formation of visually attractive rhombitrihexagonal Archimedean tiling arrangements featuring three different kinds of polygons: triangles, hexagons and rhombi. The key participation of the Cl ligands attached to the Pd(ii) centre in multiple C-H[three dots, centered]Cl interactions was demonstrated by comparing the patterns of 1 with those of an analogous non-metallic system 2.
• Embedding of a ruthenium(ii) water oxidation catalyst into nanofibers via self-assembly. Kunz, Valentin; Stepanenko, Vladimir; Würthner, Frank. In Chem. Commun., 51(2), pp. 290–293. 2015.
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  A novel ruthenium(ii) water oxidation catalyst equipped with axial perylene bisimide ligands that self-assembled into nanofibers was synthesized. This fiber-embedded catalyst exhibited improved performance compared with a monomeric reference for the oxidative water splitting reaction.

  @article{C4CC08314H, abstract = {A novel ruthenium(ii) water oxidation catalyst equipped with axial perylene bisimide ligands that self-assembled into nanofibers was synthesized. This fiber-embedded catalyst exhibited improved performance compared with a monomeric reference for the oxidative water splitting reaction.}, author = {Kunz, Valentin and Stepanenko, Vladimir and Würthner, Frank}, journal = {Chem. Commun.}, keywords = {myown}, number = 2, pages = {290-293}, publisher = {The Royal Society of Chemistry}, title = {Embedding of a ruthenium(ii) water oxidation catalyst into nanofibers via self-assembly}, volume = 51, year = 2015 }

  %0 Journal Article %1 C4CC08314H %A Kunz, Valentin %A Stepanenko, Vladimir %A Würthner, Frank %D 2015 %I The Royal Society of Chemistry %J Chem. Commun. %N 2 %P 290-293 %R 10.1039/C4CC08314H %T Embedding of a ruthenium(ii) water oxidation catalyst into nanofibers via self-assembly %U http://dx.doi.org/10.1039/C4CC08314H %V 51 %X A novel ruthenium(ii) water oxidation catalyst equipped with axial perylene bisimide ligands that self-assembled into nanofibers was synthesized. This fiber-embedded catalyst exhibited improved performance compared with a monomeric reference for the oxidative water splitting reaction.
• Organic Thin Film Transistors Based on Highly Dipolar Donor–Acceptor Polymethine Dyes. Liess, Andreas; Huang, Lizhen; Arjona-Esteban, Alhama; Lv, Aifeng; Gsänger, Marcel; Stepanenko, Vladimir; Stolte, Matthias; Würthner, Frank. In Advanced Functional Materials, 25(1), pp. 44–57. 2015.
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  Organic thin film transistors (OTFTs) of a series of twenty dipolar donor–acceptor-substituted polymethine dyes (D–A dyes, dipole moments from 3–15 D) are investigated. The employed merocyanine dyes contain a dimethine bridge that is substituted with 1-alkyl-3,3-dimethylindolin-2-ylidene (“Fischer base”), 3-alkyl-2,3-dihydrobenzothiazol-2-ylidene or 1,3-benzodithiole-2-ylidene, respectively, as electron-donating unit and various acceptor heterocycles. These studies show that thin films formed by these D–A dyes upon deposition in high vacuum are all composed of antiparallel π-stacked dimers. However, they are either amorphous, discontinuous or highly crystalline due to the interplay between molecule-substrate and dimer–dimer interactions. With the help of single crystal X-ray analysis, out-of-plane X-ray studies (XRD), selected area electron diffraction (SAED), and atomic force microscopy (AFM), a correlation between the molecular structure, film ordering, and hole charge transport ability can be established. The mobility values are compared to Bässler's disorder charge transport theory and a film growth mechanism is proposed based on DFT calculations and single crystal structures. The results show that with carefully adjusted bulky substituents and high dipolarity an intimate centrosymmetric packing with a slipped, but tight π-stacking arrangement could be realized. This provides two-dimensional percolation pathways for holes and ultimately results in charge carrier mobilities up to 0.18 cm2 V−1 s−1.

  @article{ADFM:ADFM201402678, abstract = {Organic thin film transistors (OTFTs) of a series of twenty dipolar donor–acceptor-substituted polymethine dyes (D–A dyes, dipole moments from 3–15 D) are investigated. The employed merocyanine dyes contain a dimethine bridge that is substituted with 1-alkyl-3,3-dimethylindolin-2-ylidene (“Fischer base”), 3-alkyl-2,3-dihydrobenzothiazol-2-ylidene or 1,3-benzodithiole-2-ylidene, respectively, as electron-donating unit and various acceptor heterocycles. These studies show that thin films formed by these D–A dyes upon deposition in high vacuum are all composed of antiparallel π-stacked dimers. However, they are either amorphous, discontinuous or highly crystalline due to the interplay between molecule-substrate and dimer–dimer interactions. With the help of single crystal X-ray analysis, out-of-plane X-ray studies (XRD), selected area electron diffraction (SAED), and atomic force microscopy (AFM), a correlation between the molecular structure, film ordering, and hole charge transport ability can be established. The mobility values are compared to Bässler's disorder charge transport theory and a film growth mechanism is proposed based on DFT calculations and single crystal structures. The results show that with carefully adjusted bulky substituents and high dipolarity an intimate centrosymmetric packing with a slipped, but tight π-stacking arrangement could be realized. This provides two-dimensional percolation pathways for holes and ultimately results in charge carrier mobilities up to 0.18 cm2 V−1 s−1.}, author = {Liess, Andreas and Huang, Lizhen and Arjona-Esteban, Alhama and Lv, Aifeng and Gsänger, Marcel and Stepanenko, Vladimir and Stolte, Matthias and Würthner, Frank}, journal = {Advanced Functional Materials}, keywords = {myown}, number = 1, pages = {44–57}, title = {Organic Thin Film Transistors Based on Highly Dipolar Donor–Acceptor Polymethine Dyes}, volume = 25, year = 2015 }

  %0 Journal Article %1 ADFM:ADFM201402678 %A Liess, Andreas %A Huang, Lizhen %A Arjona-Esteban, Alhama %A Lv, Aifeng %A Gsänger, Marcel %A Stepanenko, Vladimir %A Stolte, Matthias %A Würthner, Frank %D 2015 %J Advanced Functional Materials %N 1 %P 44--57 %R 10.1002/adfm.201402678 %T Organic Thin Film Transistors Based on Highly Dipolar Donor–Acceptor Polymethine Dyes %U http://dx.doi.org/10.1002/adfm.201402678 %V 25 %X Organic thin film transistors (OTFTs) of a series of twenty dipolar donor–acceptor-substituted polymethine dyes (D–A dyes, dipole moments from 3–15 D) are investigated. The employed merocyanine dyes contain a dimethine bridge that is substituted with 1-alkyl-3,3-dimethylindolin-2-ylidene (“Fischer base”), 3-alkyl-2,3-dihydrobenzothiazol-2-ylidene or 1,3-benzodithiole-2-ylidene, respectively, as electron-donating unit and various acceptor heterocycles. These studies show that thin films formed by these D–A dyes upon deposition in high vacuum are all composed of antiparallel π-stacked dimers. However, they are either amorphous, discontinuous or highly crystalline due to the interplay between molecule-substrate and dimer–dimer interactions. With the help of single crystal X-ray analysis, out-of-plane X-ray studies (XRD), selected area electron diffraction (SAED), and atomic force microscopy (AFM), a correlation between the molecular structure, film ordering, and hole charge transport ability can be established. The mobility values are compared to Bässler's disorder charge transport theory and a film growth mechanism is proposed based on DFT calculations and single crystal structures. The results show that with carefully adjusted bulky substituents and high dipolarity an intimate centrosymmetric packing with a slipped, but tight π-stacking arrangement could be realized. This provides two-dimensional percolation pathways for holes and ultimately results in charge carrier mobilities up to 0.18 cm2 V−1 s−1.
• Ambient Stable Zwitterionic Perylene Bisimide-Centered Radical. Schmidt, David; Bialas, David; Würthner, Frank. In Angew. Chem. Int. Ed., 54(12), pp. 3611–3614. 2015.
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  The unexpected introduction of a cationic imidazolium substituent in the 2-position of a tetrachloro-substituted perylene-3,4:9,10-tetracarboxylic acid bisimide (PBI) by the reaction of PBI-Cl4 1 with the N-heterocyclic carbene 1,3-di-iso-propyl-imidazolin-2-ylidene (iPr2Im 2) enables the isolation of an ambient stable zwitterionic radical. The remarkable stability of this unprecedented PBI-centered radical facilitates the complete characterization by several spectroscopic methods as well as single crystal structure analysis. Redox studies revealed that iPr2Im-PBI-Cl4 4 can be transferred reversibly to the corresponding anion and cation, respectively, even on a preparative scale.

  @article{ANIE:ANIE201408067, abstract = {The unexpected introduction of a cationic imidazolium substituent in the 2-position of a tetrachloro-substituted perylene-3,4:9,10-tetracarboxylic acid bisimide (PBI) by the reaction of PBI-Cl4 1 with the N-heterocyclic carbene 1,3-di-iso-propyl-imidazolin-2-ylidene (iPr2Im 2) enables the isolation of an ambient stable zwitterionic radical. The remarkable stability of this unprecedented PBI-centered radical facilitates the complete characterization by several spectroscopic methods as well as single crystal structure analysis. Redox studies revealed that iPr2Im-PBI-Cl4 4 can be transferred reversibly to the corresponding anion and cation, respectively, even on a preparative scale.}, author = {Schmidt, David and Bialas, David and Würthner, Frank}, journal = {Angew. Chem. Int. Ed.}, keywords = {myown}, number = 12, pages = {3611–3614}, publisher = {WILEY-VCH Verlag}, title = {Ambient Stable Zwitterionic Perylene Bisimide-Centered Radical}, volume = 54, year = 2015 }

  %0 Journal Article %1 ANIE:ANIE201408067 %A Schmidt, David %A Bialas, David %A Würthner, Frank %D 2015 %I WILEY-VCH Verlag %J Angew. Chem. Int. Ed. %N 12 %P 3611--3614 %R 10.1002/anie.201408067 %T Ambient Stable Zwitterionic Perylene Bisimide-Centered Radical %U http://dx.doi.org/10.1002/anie.201408067 %V 54 %X The unexpected introduction of a cationic imidazolium substituent in the 2-position of a tetrachloro-substituted perylene-3,4:9,10-tetracarboxylic acid bisimide (PBI) by the reaction of PBI-Cl4 1 with the N-heterocyclic carbene 1,3-di-iso-propyl-imidazolin-2-ylidene (iPr2Im 2) enables the isolation of an ambient stable zwitterionic radical. The remarkable stability of this unprecedented PBI-centered radical facilitates the complete characterization by several spectroscopic methods as well as single crystal structure analysis. Redox studies revealed that iPr2Im-PBI-Cl4 4 can be transferred reversibly to the corresponding anion and cation, respectively, even on a preparative scale.
• Near-IR Phosphorescent Ruthenium(II) and Iridium(III) Perylene Bisimide Metal Complexes. Schulze, Marcus; Steffen, Andreas; Würthner, Frank. In Angew. Chem. Int. Ed., 54(5), pp. 1570–1573. 2015.
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  The phosphorescence emission of perylene bisimide derivatives has been rarely reported. Two novel ruthenium(II) and iridium(III) complexes of an azabenz-annulated perylene bisimide (ab-PBI), [Ru(bpy)2(ab-PBI)][PF6]2 1 and [Cp*Ir(ab-PBI)Cl]PF6 2 are now presented that both show NIR phosphorescence between 750–1000 nm in solution at room temperature. For an NIR emitter, the ruthenium complex 1 displays an unusually high quantum yield (Φp) of 11 % with a lifetime (τp) of 4.2 μs, while iridium complex 2 exhibits Φp<1 % and τp=33 μs. 1 and 2 are the first PBI-metal complexes in which the spin–orbit coupling is strong enough to facilitate not only the Sn→Tn intersystem crossing of the PBI dye, but also the radiative T1→S0 transition, that is, phosphorescence.

  @article{ANIE:ANIE201410437, abstract = {The phosphorescence emission of perylene bisimide derivatives has been rarely reported. Two novel ruthenium(II) and iridium(III) complexes of an azabenz-annulated perylene bisimide (ab-PBI), [Ru(bpy)2(ab-PBI)][PF6]2 1 and [Cp*Ir(ab-PBI)Cl]PF6 2 are now presented that both show NIR phosphorescence between 750–1000 nm in solution at room temperature. For an NIR emitter, the ruthenium complex 1 displays an unusually high quantum yield (Φp) of 11 % with a lifetime (τp) of 4.2 μs, while iridium complex 2 exhibits Φp<1 % and τp=33 μs. 1 and 2 are the first PBI-metal complexes in which the spin–orbit coupling is strong enough to facilitate not only the Sn→Tn intersystem crossing of the PBI dye, but also the radiative T1→S0 transition, that is, phosphorescence.}, author = {Schulze, Marcus and Steffen, Andreas and Würthner, Frank}, journal = {Angew. Chem. Int. Ed.}, keywords = {myown}, number = 5, pages = {1570–1573}, publisher = {WILEY-VCH Verlag}, title = {Near-IR Phosphorescent Ruthenium(II) and Iridium(III) Perylene Bisimide Metal Complexes}, volume = 54, year = 2015 }

  %0 Journal Article %1 ANIE:ANIE201410437 %A Schulze, Marcus %A Steffen, Andreas %A Würthner, Frank %D 2015 %I WILEY-VCH Verlag %J Angew. Chem. Int. Ed. %N 5 %P 1570--1573 %R 10.1002/anie.201410437 %T Near-IR Phosphorescent Ruthenium(II) and Iridium(III) Perylene Bisimide Metal Complexes %U http://dx.doi.org/10.1002/anie.201410437 %V 54 %X The phosphorescence emission of perylene bisimide derivatives has been rarely reported. Two novel ruthenium(II) and iridium(III) complexes of an azabenz-annulated perylene bisimide (ab-PBI), [Ru(bpy)2(ab-PBI)][PF6]2 1 and [Cp*Ir(ab-PBI)Cl]PF6 2 are now presented that both show NIR phosphorescence between 750–1000 nm in solution at room temperature. For an NIR emitter, the ruthenium complex 1 displays an unusually high quantum yield (Φp) of 11 % with a lifetime (τp) of 4.2 μs, while iridium complex 2 exhibits Φp<1 % and τp=33 μs. 1 and 2 are the first PBI-metal complexes in which the spin–orbit coupling is strong enough to facilitate not only the Sn→Tn intersystem crossing of the PBI dye, but also the radiative T1→S0 transition, that is, phosphorescence.
• Direct observation of ultrafast coherent exciton dynamics in helical π-stacks of self-assembled perylene bisimides. Sung, Jooyoung; Kim, Pyosang; Fimmel, Benjamin; Würthner, Frank; Kim, Dongho. 6, p. 8646-. 2015.
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  Ever since the discovery of dye self-assemblies in nature, there have been tremendous efforts to exploit biomimetic supramolecular assemblies for tailored artificial photon processing materials. This feature necessarily has resulted in an increasing demand for understanding exciton dynamics in the dye self-assemblies. In a sharp contrast with J-type aggregates, however, the detailed observation of exciton dynamics in H-type aggregates has remained challenging. In this study, as we succeed in measuring transient fluorescence from Frenkel state of π-stacked perylene tetracarboxylic acid bisimide dimer and oligomer aggregates, we present an experimental demonstration on Frenkel exciton dynamics of archetypal columnar π–π stacks of dyes. The analysis of the vibronic peak ratio of the transient fluorescence spectra reveals that unlike the simple π-stacked dimer, the photoexcitation energy in the columnar π-stacked oligomer aggregates is initially delocalized over at least three molecular units and moves coherently along the chain in tens of femtoseconds, preceding excimer formation process.

  @article{sung2015direct, abstract = {Ever since the discovery of dye self-assemblies in nature, there have been tremendous efforts to exploit biomimetic supramolecular assemblies for tailored artificial photon processing materials. This feature necessarily has resulted in an increasing demand for understanding exciton dynamics in the dye self-assemblies. In a sharp contrast with J-type aggregates, however, the detailed observation of exciton dynamics in H-type aggregates has remained challenging. In this study, as we succeed in measuring transient fluorescence from Frenkel state of π-stacked perylene tetracarboxylic acid bisimide dimer and oligomer aggregates, we present an experimental demonstration on Frenkel exciton dynamics of archetypal columnar π–π stacks of dyes. The analysis of the vibronic peak ratio of the transient fluorescence spectra reveals that unlike the simple π-stacked dimer, the photoexcitation energy in the columnar π-stacked oligomer aggregates is initially delocalized over at least three molecular units and moves coherently along the chain in tens of femtoseconds, preceding excimer formation process.}, author = {Sung, Jooyoung and Kim, Pyosang and Fimmel, Benjamin and Würthner, Frank and Kim, Dongho}, keywords = {myown}, month = 10, pages = {8646–}, publisher = {The Author(s)}, title = {Direct observation of ultrafast coherent exciton dynamics in helical π-stacks of self-assembled perylene bisimides}, volume = 6, year = 2015 }

  %0 Journal Article %1 sung2015direct %A Sung, Jooyoung %A Kim, Pyosang %A Fimmel, Benjamin %A Würthner, Frank %A Kim, Dongho %D 2015 %I The Author(s) %P 8646-- %R 10.1038/ncomms9646 %T Direct observation of ultrafast coherent exciton dynamics in helical π-stacks of self-assembled perylene bisimides %U http://dx.doi.org/10.1038/ncomms9646 %V 6 %X Ever since the discovery of dye self-assemblies in nature, there have been tremendous efforts to exploit biomimetic supramolecular assemblies for tailored artificial photon processing materials. This feature necessarily has resulted in an increasing demand for understanding exciton dynamics in the dye self-assemblies. In a sharp contrast with J-type aggregates, however, the detailed observation of exciton dynamics in H-type aggregates has remained challenging. In this study, as we succeed in measuring transient fluorescence from Frenkel state of π-stacked perylene tetracarboxylic acid bisimide dimer and oligomer aggregates, we present an experimental demonstration on Frenkel exciton dynamics of archetypal columnar π–π stacks of dyes. The analysis of the vibronic peak ratio of the transient fluorescence spectra reveals that unlike the simple π-stacked dimer, the photoexcitation energy in the columnar π-stacked oligomer aggregates is initially delocalized over at least three molecular units and moves coherently along the chain in tens of femtoseconds, preceding excimer formation process.
• Spacer-Modulated Differentiation Between Self-Assembly and Folding Pathways for Bichromophoric Merocyanine Dyes. Zitzler-Kunkel, André; Kirchner, Eva; Bialas, David; Simon, Christian; Würthner, Frank. In Chemistry – A European Journal, 21(42), pp. 14851–14861. 2015.
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  We have synthesized a large series of bis(merocyanine) dyes with varying spacer unit and investigated in detail their self-organization behavior by concentration- as well as solvent-dependent UV/Vis spectroscopy. Our in-depth studies have shown that the self-organization of the present bis(merocyanine) dyes is subtly influenced by the nature of the spacer unit. The utilization of rigid spacers results in the formation of self-associated bimolecular complexes with high binding strength, while flexible spacers drive the respective bichromophoric dyes to intramolecular folding. Our thorough investigations on the impact of alkyl spacer chain length on the folding tendency of the present series of bis(merocyanine) dyes revealed a biphasic behavior, that is, a steep increase of the folding tendency for the dyes containing C4 to C7 chains and then a gentle decrease for dyes with longer alkyl spacer chains as evidenced by free energy (ΔG) values for the folding of these dyes. Furthermore, analyses of aggregates’ optical properties based on exciton theory as well as quantum chemical calculations suggest a bimolecular aggregate structure for the dye possessing a rigid spacer and a rotationally twisted pleated structure for the bis(merocyanine) dyes having spacer units with less than seven carbon atoms, while the application of longer alkyl chain linkers (≥C7) provides enough flexibility to orient the chromophores in electrostatically most favored antiparallel fashion.

  @article{CHEM:CHEM201502434, abstract = {We have synthesized a large series of bis(merocyanine) dyes with varying spacer unit and investigated in detail their self-organization behavior by concentration- as well as solvent-dependent UV/Vis spectroscopy. Our in-depth studies have shown that the self-organization of the present bis(merocyanine) dyes is subtly influenced by the nature of the spacer unit. The utilization of rigid spacers results in the formation of self-associated bimolecular complexes with high binding strength, while flexible spacers drive the respective bichromophoric dyes to intramolecular folding. Our thorough investigations on the impact of alkyl spacer chain length on the folding tendency of the present series of bis(merocyanine) dyes revealed a biphasic behavior, that is, a steep increase of the folding tendency for the dyes containing C4 to C7 chains and then a gentle decrease for dyes with longer alkyl spacer chains as evidenced by free energy (ΔG) values for the folding of these dyes. Furthermore, analyses of aggregates’ optical properties based on exciton theory as well as quantum chemical calculations suggest a bimolecular aggregate structure for the dye possessing a rigid spacer and a rotationally twisted pleated structure for the bis(merocyanine) dyes having spacer units with less than seven carbon atoms, while the application of longer alkyl chain linkers (≥C7) provides enough flexibility to orient the chromophores in electrostatically most favored antiparallel fashion.}, author = {Zitzler-Kunkel, André and Kirchner, Eva and Bialas, David and Simon, Christian and Würthner, Frank}, journal = {Chemistry – A European Journal}, keywords = {myown}, number = 42, pages = {14851–14861}, publisher = {WILEY-VCH Verlag}, title = {Spacer-Modulated Differentiation Between Self-Assembly and Folding Pathways for Bichromophoric Merocyanine Dyes}, volume = 21, year = 2015 }

  %0 Journal Article %1 CHEM:CHEM201502434 %A Zitzler-Kunkel, André %A Kirchner, Eva %A Bialas, David %A Simon, Christian %A Würthner, Frank %D 2015 %I WILEY-VCH Verlag %J Chemistry – A European Journal %N 42 %P 14851--14861 %R 10.1002/chem.201502434 %T Spacer-Modulated Differentiation Between Self-Assembly and Folding Pathways for Bichromophoric Merocyanine Dyes %U http://dx.doi.org/10.1002/chem.201502434 %V 21 %X We have synthesized a large series of bis(merocyanine) dyes with varying spacer unit and investigated in detail their self-organization behavior by concentration- as well as solvent-dependent UV/Vis spectroscopy. Our in-depth studies have shown that the self-organization of the present bis(merocyanine) dyes is subtly influenced by the nature of the spacer unit. The utilization of rigid spacers results in the formation of self-associated bimolecular complexes with high binding strength, while flexible spacers drive the respective bichromophoric dyes to intramolecular folding. Our thorough investigations on the impact of alkyl spacer chain length on the folding tendency of the present series of bis(merocyanine) dyes revealed a biphasic behavior, that is, a steep increase of the folding tendency for the dyes containing C4 to C7 chains and then a gentle decrease for dyes with longer alkyl spacer chains as evidenced by free energy (ΔG) values for the folding of these dyes. Furthermore, analyses of aggregates’ optical properties based on exciton theory as well as quantum chemical calculations suggest a bimolecular aggregate structure for the dye possessing a rigid spacer and a rotationally twisted pleated structure for the bis(merocyanine) dyes having spacer units with less than seven carbon atoms, while the application of longer alkyl chain linkers (≥C7) provides enough flexibility to orient the chromophores in electrostatically most favored antiparallel fashion.
• An ambient stable core-substituted perylene bisimide dianion: isolation and single crystal structure analysis. Seifert, Sabine; Schmidt, David; Würthner, Frank. In Chem. Sci., 6(3), pp. 1663–1667. 2015.
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  Here we report the first example of an isolable, ambient stable perylene bisimide (PBI) dianion which was synthesized by catalytic reduction of a highly electron deficient PBI derivative. The remarkable stability of this unprecedented dianion in air for months facilitated its complete characterization by different methods, including single crystal X-ray analysis. Furthermore, solvent dependent cyclic and square wave voltammetry studies revealed that the formation of PBI dianions is preferred in more polar solvents, whereas the generation of PBI radical anions should be favoured in less polar solvents.

  @article{C4SC03671A, abstract = {Here we report the first example of an isolable{,} ambient stable perylene bisimide (PBI) dianion which was synthesized by catalytic reduction of a highly electron deficient PBI derivative. The remarkable stability of this unprecedented dianion in air for months facilitated its complete characterization by different methods{,} including single crystal X-ray analysis. Furthermore{,} solvent dependent cyclic and square wave voltammetry studies revealed that the formation of PBI dianions is preferred in more polar solvents{,} whereas the generation of PBI radical anions should be favoured in less polar solvents.}, author = {Seifert, Sabine and Schmidt, David and Würthner, Frank}, journal = {Chem. Sci.}, keywords = {myown}, number = 3, pages = {1663-1667}, publisher = {The Royal Society of Chemistry}, title = {An ambient stable core-substituted perylene bisimide dianion: isolation and single crystal structure analysis}, volume = 6, year = 2015 }

  %0 Journal Article %1 C4SC03671A %A Seifert, Sabine %A Schmidt, David %A Würthner, Frank %D 2015 %I The Royal Society of Chemistry %J Chem. Sci. %N 3 %P 1663-1667 %R 10.1039/C4SC03671A %T An ambient stable core-substituted perylene bisimide dianion: isolation and single crystal structure analysis %U http://dx.doi.org/10.1039/C4SC03671A %V 6 %X Here we report the first example of an isolable, ambient stable perylene bisimide (PBI) dianion which was synthesized by catalytic reduction of a highly electron deficient PBI derivative. The remarkable stability of this unprecedented dianion in air for months facilitated its complete characterization by different methods, including single crystal X-ray analysis. Furthermore, solvent dependent cyclic and square wave voltammetry studies revealed that the formation of PBI dianions is preferred in more polar solvents, whereas the generation of PBI radical anions should be favoured in less polar solvents.
• Photoinduced electron transfer (PET) versus excimer formation in supramolecular p/n-heterojunctions of perylene bisimide dyes and implications for organic photovoltaics. Nowak-Krol, Agnieszka; Fimmel, Benjamin; Son, Minjung; Kim, Dongho; Würthner, Frank. In Faraday Discuss., 185, pp. 507–527. 2015.
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  Foldamer systems comprised of two perylene bisimide (PBI) dyes attached to the conjugated backbones of 1,2-bis(phenylethynyl)benzene and phenylethynyl-bis(phenylene)indane, respectively, were synthesized and investigated with regard to their solvent-dependent properties. UV/Vis absorption and steady-state fluorescence spectra show that both foldamers exist predominantly in a folded H-aggregated state consisting of [small pi]-[small pi]-stacked PBIs in THF and in more random conformations with weaker excitonic coupling between the PBIs in chloroform. Time-resolved fluorescence spectroscopy and transient absorption spectroscopy reveal entirely different relaxation pathways for the photoexcited molecules in the given solvents, i.e. photoinduced electron transfer leading to charge separated states for the open conformations (in chloroform) and relaxation into excimer states with red-shifted emission for the stacked conformations (in THF). Supported by redox data from cyclic voltammetry and Rehm-Weller analysis we could relate the processes occurring in these solution-phase model systems to the elementary processes in organic solar cells. Accordingly, only if relaxation pathways such as excimer formation are strictly avoided in molecular semiconductor materials, excitons may diffuse over larger distances to the heterojunction interface and produce photocurrent via the formation of electron/hole pairs by photoinduced electron transfer.

  @article{C5FD00052A, abstract = {Foldamer systems comprised of two perylene bisimide (PBI) dyes attached to the conjugated backbones of 1{,}2-bis(phenylethynyl)benzene and phenylethynyl-bis(phenylene)indane{,} respectively{,} were synthesized and investigated with regard to their solvent-dependent properties. UV/Vis absorption and steady-state fluorescence spectra show that both foldamers exist predominantly in a folded H-aggregated state consisting of [small pi]-[small pi]-stacked PBIs in THF and in more random conformations with weaker excitonic coupling between the PBIs in chloroform. Time-resolved fluorescence spectroscopy and transient absorption spectroscopy reveal entirely different relaxation pathways for the photoexcited molecules in the given solvents{,} i.e. photoinduced electron transfer leading to charge separated states for the open conformations (in chloroform) and relaxation into excimer states with red-shifted emission for the stacked conformations (in THF). Supported by redox data from cyclic voltammetry and Rehm-Weller analysis we could relate the processes occurring in these solution-phase model systems to the elementary processes in organic solar cells. Accordingly{,} only if relaxation pathways such as excimer formation are strictly avoided in molecular semiconductor materials{,} excitons may diffuse over larger distances to the heterojunction interface and produce photocurrent via the formation of electron/hole pairs by photoinduced electron transfer.}, author = {Nowak-Krol, Agnieszka and Fimmel, Benjamin and Son, Minjung and Kim, Dongho and Würthner, Frank}, journal = {Faraday Discuss.}, keywords = {myown}, pages = {507-527}, publisher = {The Royal Society of Chemistry}, title = {Photoinduced electron transfer (PET) versus excimer formation in supramolecular p/n-heterojunctions of perylene bisimide dyes and implications for organic photovoltaics}, volume = 185, year = 2015 }

  %0 Journal Article %1 C5FD00052A %A Nowak-Krol, Agnieszka %A Fimmel, Benjamin %A Son, Minjung %A Kim, Dongho %A Würthner, Frank %D 2015 %I The Royal Society of Chemistry %J Faraday Discuss. %P 507-527 %R 10.1039/C5FD00052A %T Photoinduced electron transfer (PET) versus excimer formation in supramolecular p/n-heterojunctions of perylene bisimide dyes and implications for organic photovoltaics %U http://dx.doi.org/10.1039/C5FD00052A %V 185 %X Foldamer systems comprised of two perylene bisimide (PBI) dyes attached to the conjugated backbones of 1,2-bis(phenylethynyl)benzene and phenylethynyl-bis(phenylene)indane, respectively, were synthesized and investigated with regard to their solvent-dependent properties. UV/Vis absorption and steady-state fluorescence spectra show that both foldamers exist predominantly in a folded H-aggregated state consisting of [small pi]-[small pi]-stacked PBIs in THF and in more random conformations with weaker excitonic coupling between the PBIs in chloroform. Time-resolved fluorescence spectroscopy and transient absorption spectroscopy reveal entirely different relaxation pathways for the photoexcited molecules in the given solvents, i.e. photoinduced electron transfer leading to charge separated states for the open conformations (in chloroform) and relaxation into excimer states with red-shifted emission for the stacked conformations (in THF). Supported by redox data from cyclic voltammetry and Rehm-Weller analysis we could relate the processes occurring in these solution-phase model systems to the elementary processes in organic solar cells. Accordingly, only if relaxation pathways such as excimer formation are strictly avoided in molecular semiconductor materials, excitons may diffuse over larger distances to the heterojunction interface and produce photocurrent via the formation of electron/hole pairs by photoinduced electron transfer.
• Single-crystal field-effect transistors of new Cl2-NDI polymorph processed by sublimation in air. He, Tao; Stolte, Matthias; Burschka, Christian; Hansen, Nis Hauke; Musiol, Thomas; Kälblein, Daniel; Pflaum, Jens; Tao, Xutang; Brill, Jochen; Würthner, Frank. 6, p. 5954-. 2015.
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  @article{he2015singlecrystal, author = {He, Tao and Stolte, Matthias and Burschka, Christian and Hansen, Nis Hauke and Musiol, Thomas and Kälblein, Daniel and Pflaum, Jens and Tao, Xutang and Brill, Jochen and Würthner, Frank}, keywords = {myown}, month = {01}, pages = {5954–}, publisher = {Nature Publishing Group, a division of Macmillan Publishers Limited. All Rights Reserved.}, title = {Single-crystal field-effect transistors of new Cl2-NDI polymorph processed by sublimation in air}, volume = 6, year = 2015 }

  %0 Journal Article %1 he2015singlecrystal %A He, Tao %A Stolte, Matthias %A Burschka, Christian %A Hansen, Nis Hauke %A Musiol, Thomas %A Kälblein, Daniel %A Pflaum, Jens %A Tao, Xutang %A Brill, Jochen %A Würthner, Frank %D 2015 %I Nature Publishing Group, a division of Macmillan Publishers Limited. All Rights Reserved. %P 5954-- %T Single-crystal field-effect transistors of new Cl2-NDI polymorph processed by sublimation in air %U http://dx.doi.org/10.1038/ncomms6954 %V 6
• Supramolecular block copolymers by kinetically controlled co-self-assembly of planar and core-twisted perylene bisimides. Görl, Daniel; Zhang, Xin; Stepanenko, Vladimir; Würthner, Frank. In Nature Communications, 6, p. 7009-. 2015.
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  New synthetic methodologies for the formation of block copolymers have revolutionized polymer science within the last two decades. However, the formation of supramolecular block copolymers composed of alternating sequences of larger block segments has not been realized yet. Here we show by transmission electron microscopy (TEM), 2D NMR and optical spectroscopy that two different perylene bisimide dyes bearing either a flat (A) or a twisted (B) core self-assemble in water into supramolecular block copolymers with an alternating sequence of (AmBB)n. The highly defined ultralong nanowire structure of these supramolecular copolymers is entirely different from those formed upon self-assembly of the individual counterparts, that is, stiff nanorods (A) and irregular nanoworms (B), respectively. Our studies further reveal that the as-formed supramolecular block copolymer constitutes a kinetic self-assembly product that transforms into thermodynamically more stable self-sorted homopolymers upon heating.

  @article{gorl2015supramolecular, abstract = {New synthetic methodologies for the formation of block copolymers have revolutionized polymer science within the last two decades. However, the formation of supramolecular block copolymers composed of alternating sequences of larger block segments has not been realized yet. Here we show by transmission electron microscopy (TEM), 2D NMR and optical spectroscopy that two different perylene bisimide dyes bearing either a flat (A) or a twisted (B) core self-assemble in water into supramolecular block copolymers with an alternating sequence of (AmBB)n. The highly defined ultralong nanowire structure of these supramolecular copolymers is entirely different from those formed upon self-assembly of the individual counterparts, that is, stiff nanorods (A) and irregular nanoworms (B), respectively. Our studies further reveal that the as-formed supramolecular block copolymer constitutes a kinetic self-assembly product that transforms into thermodynamically more stable self-sorted homopolymers upon heating.}, author = {Görl, Daniel and Zhang, Xin and Stepanenko, Vladimir and Würthner, Frank}, journal = {Nature Communications}, keywords = {myown}, month = {05}, pages = {7009–}, publisher = {The Author(s)}, title = {Supramolecular block copolymers by kinetically controlled co-self-assembly of planar and core-twisted perylene bisimides}, volume = 6, year = 2015 }

  %0 Journal Article %1 gorl2015supramolecular %A Görl, Daniel %A Zhang, Xin %A Stepanenko, Vladimir %A Würthner, Frank %D 2015 %I The Author(s) %J Nature Communications %P 7009-- %R doi:10.1038/ncomms8009 %T Supramolecular block copolymers by kinetically controlled co-self-assembly of planar and core-twisted perylene bisimides %U http://dx.doi.org/10.1038/ncomms8009 %V 6 %X New synthetic methodologies for the formation of block copolymers have revolutionized polymer science within the last two decades. However, the formation of supramolecular block copolymers composed of alternating sequences of larger block segments has not been realized yet. Here we show by transmission electron microscopy (TEM), 2D NMR and optical spectroscopy that two different perylene bisimide dyes bearing either a flat (A) or a twisted (B) core self-assemble in water into supramolecular block copolymers with an alternating sequence of (AmBB)n. The highly defined ultralong nanowire structure of these supramolecular copolymers is entirely different from those formed upon self-assembly of the individual counterparts, that is, stiff nanorods (A) and irregular nanoworms (B), respectively. Our studies further reveal that the as-formed supramolecular block copolymer constitutes a kinetic self-assembly product that transforms into thermodynamically more stable self-sorted homopolymers upon heating.

• Synthesis and Properties of a New Class of Fully Conjugated Azahexacene Analogues. Yue, Wan; Suraru, Sabin-Lucian; Bialas, David; Müller, Matthias; Würthner, Frank. In Angew. Chem. Int. Ed., 53(24), pp. 6159–6162. 2014.
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  Acenes are a traditional class of polycyclic aromatic hydrocarbons (PAHs) which attracted considerable interest during the last decade because of their outstanding p-channel semiconductor properties. More recently, N-heteroacenes have been prepared. These molecules have been shown to be more stable and can exhibit n-channel semiconductor properties. Inspired by these archetype PAHs, we synthesized a novel class of highly persistent azahexacene analogues 3 a–d. These molecules are composed of a core of four fused five-membered rings derived from their respective diketopyrrolopyrroles. These new π-conjugated scaffolds show broad and intense absorption in the visible region and possess low-lying HOMO and LUMO levels, leading to much better stability compared to that of acenes and most heteroacenes.

  @article{ANIE:ANIE201403227, abstract = {Acenes are a traditional class of polycyclic aromatic hydrocarbons (PAHs) which attracted considerable interest during the last decade because of their outstanding p-channel semiconductor properties. More recently, N-heteroacenes have been prepared. These molecules have been shown to be more stable and can exhibit n-channel semiconductor properties. Inspired by these archetype PAHs, we synthesized a novel class of highly persistent azahexacene analogues 3 a–d. These molecules are composed of a core of four fused five-membered rings derived from their respective diketopyrrolopyrroles. These new π-conjugated scaffolds show broad and intense absorption in the visible region and possess low-lying HOMO and LUMO levels, leading to much better stability compared to that of acenes and most heteroacenes.}, author = {Yue, Wan and Suraru, Sabin-Lucian and Bialas, David and Müller, Matthias and Würthner, Frank}, journal = {Angew. Chem. Int. Ed.}, keywords = {myown}, number = 24, pages = {6159–6162}, publisher = {WILEY-VCH Verlag}, title = {Synthesis and Properties of a New Class of Fully Conjugated Azahexacene Analogues}, volume = 53, year = 2014 }

  %0 Journal Article %1 ANIE:ANIE201403227 %A Yue, Wan %A Suraru, Sabin-Lucian %A Bialas, David %A Müller, Matthias %A Würthner, Frank %D 2014 %I WILEY-VCH Verlag %J Angew. Chem. Int. Ed. %N 24 %P 6159--6162 %R 10.1002/anie.201403227 %T Synthesis and Properties of a New Class of Fully Conjugated Azahexacene Analogues %U http://dx.doi.org/10.1002/anie.201403227 %V 53 %X Acenes are a traditional class of polycyclic aromatic hydrocarbons (PAHs) which attracted considerable interest during the last decade because of their outstanding p-channel semiconductor properties. More recently, N-heteroacenes have been prepared. These molecules have been shown to be more stable and can exhibit n-channel semiconductor properties. Inspired by these archetype PAHs, we synthesized a novel class of highly persistent azahexacene analogues 3 a–d. These molecules are composed of a core of four fused five-membered rings derived from their respective diketopyrrolopyrroles. These new π-conjugated scaffolds show broad and intense absorption in the visible region and possess low-lying HOMO and LUMO levels, leading to much better stability compared to that of acenes and most heteroacenes.
• NIR-Absorbing Merocyanine Dyes for BHJ Solar Cells. Zitzler-Kunkel, André; Lenze, Martin R.; Kronenberg, Nils M.; Krause, Ana-Maria; Stolte, Matthias; Meerholz, Klaus; Würthner, Frank. In Chemistry of Materials, 26(16), pp. 4856–4866. 2014.
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  • [ DOI ]
  We have synthesized a series of new, polymethine chain extended merocyanine dyes 1–4 bearing varied acceptor units and an aminothiophene donor moiety. The optical and electronic properties of these new merocyanines have been studied in comparison with their corresponding lower homologues 5–8, which contain two methine groups less, by UV–vis and electro-optical absorption (EOA) spectroscopy and cyclic voltammetry. The absorption spectra of π-extended merocyanines are markedly red-shifted, and their extinction coefficients are significantly increased compared to those of their lower homologues. The photovoltaic characteristics of these dyes have been explored in devices using them as donor and PC61BM fullerene as acceptor materials. Our detailed studies reveal that, despite more favorable absorption properties, the π-extended merocyanines exhibit lower short-circuit current densities (JSC) as well as decreased open-circuit voltages (VOC) and power conversion efficiencies (PCE) compared with those of their respective lower homologues. The unexpected decreased JSC values could be explained in terms of looser packing features of π-extended chromophores in the solid state as revealed by single-crystal X-ray analysis of two pairs (1/5 and 4/8) of these dyes. By optimization of device setup PCE of 2.3\% has been achieved with the π-extended donor material 4.

  @article{doi:10.1021/cm502302s, abstract = {We have synthesized a series of new, polymethine chain extended merocyanine dyes 1–4 bearing varied acceptor units and an aminothiophene donor moiety. The optical and electronic properties of these new merocyanines have been studied in comparison with their corresponding lower homologues 5–8, which contain two methine groups less, by UV–vis and electro-optical absorption (EOA) spectroscopy and cyclic voltammetry. The absorption spectra of π-extended merocyanines are markedly red-shifted, and their extinction coefficients are significantly increased compared to those of their lower homologues. The photovoltaic characteristics of these dyes have been explored in devices using them as donor and PC61BM fullerene as acceptor materials. Our detailed studies reveal that, despite more favorable absorption properties, the π-extended merocyanines exhibit lower short-circuit current densities (JSC) as well as decreased open-circuit voltages (VOC) and power conversion efficiencies (PCE) compared with those of their respective lower homologues. The unexpected decreased JSC values could be explained in terms of looser packing features of π-extended chromophores in the solid state as revealed by single-crystal X-ray analysis of two pairs (1/5 and 4/8) of these dyes. By optimization of device setup PCE of 2.3\% has been achieved with the π-extended donor material 4.}, author = {Zitzler-Kunkel, André and Lenze, Martin R. and Kronenberg, Nils M. and Krause, Ana-Maria and Stolte, Matthias and Meerholz, Klaus and Würthner, Frank}, journal = {Chemistry of Materials}, keywords = {myown}, number = 16, pages = {4856-4866}, title = {NIR-Absorbing Merocyanine Dyes for BHJ Solar Cells}, volume = 26, year = 2014 }

  %0 Journal Article %1 doi:10.1021/cm502302s %A Zitzler-Kunkel, André %A Lenze, Martin R. %A Kronenberg, Nils M. %A Krause, Ana-Maria %A Stolte, Matthias %A Meerholz, Klaus %A Würthner, Frank %D 2014 %J Chemistry of Materials %N 16 %P 4856-4866 %R 10.1021/cm502302s %T NIR-Absorbing Merocyanine Dyes for BHJ Solar Cells %U http://dx.doi.org/10.1021/cm502302s %V 26 %X We have synthesized a series of new, polymethine chain extended merocyanine dyes 1–4 bearing varied acceptor units and an aminothiophene donor moiety. The optical and electronic properties of these new merocyanines have been studied in comparison with their corresponding lower homologues 5–8, which contain two methine groups less, by UV–vis and electro-optical absorption (EOA) spectroscopy and cyclic voltammetry. The absorption spectra of π-extended merocyanines are markedly red-shifted, and their extinction coefficients are significantly increased compared to those of their lower homologues. The photovoltaic characteristics of these dyes have been explored in devices using them as donor and PC61BM fullerene as acceptor materials. Our detailed studies reveal that, despite more favorable absorption properties, the π-extended merocyanines exhibit lower short-circuit current densities (JSC) as well as decreased open-circuit voltages (VOC) and power conversion efficiencies (PCE) compared with those of their respective lower homologues. The unexpected decreased JSC values could be explained in terms of looser packing features of π-extended chromophores in the solid state as revealed by single-crystal X-ray analysis of two pairs (1/5 and 4/8) of these dyes. By optimization of device setup PCE of 2.3\% has been achieved with the π-extended donor material 4.
• Nano-Confined Squaraine Dye Assemblies: New Photoacoustic and Near-Infrared Fluorescence Dual-Modular Imaging Probes in Vivo. Zhang, Di; Zhao, Ying-Xi; Qiao, Zeng-Ying; Mayerhöffer, Ulrich; Spenst, Peter; Li, Xiao-Jun; Würthner, Frank; Wang, Hao. In Bioconjugate Chemistry, 25(11), pp. 2021–2029. 2014.

  PMID: 25370305
  • [ Abstract ]
  • [ BibTeX ]
  • [ EndNote ]
  • [ DOI ]
  For the purpose of near-infrared (NIR) fluorescence and photoacoustic (PA) tomography dual-modular imaging, self-assembly of squaraine (SQ) dyes is constructed in the hydrophobic phospholipid bilayers of liposomes (SQ⊂L) with variable mixing ratios of SQ and phospholipids from 1:500 to 1:10 (w/w). When doping minimal amounts of SQ, molecularly dispersed SQ in bilayers shows remarkable fluorescence. Interesting, the PA signal is enhanced with increase of SQ in the nanoconfined bilayer region, which is attributed to the formation of SQ-based H-aggregates and enhanced thermal conversion efficiency (η). SQ⊂L shows satisfactory chemical and thermal stabilities and photobleaching resistance. SQ⊂L is well-distributed in the cytoplasm of MCF-7 cells and its fluorescence signal remains for 7 days without dramatic quenching owing to the good stability of SQ⊂L. Furthermore, SQ⊂L is subjected to in vivo NIR fluorescence imaging to evaluate the whole-body biodistribution in organ level. Particularly, PA imaging with deeper tissue penetration capability is utilized to investigate the heterogeneous distribution SQ⊂L inside solid tumor. The majority of SQ⊂L are enriched in the area where the blood vessels are generated, implying that the liposomal nanocarriers exhibit lower tumor tissue penetration capability after the vascular leakage. This result is validated by histological examination of tumor tissue in parallel.

  @article{doi:10.1021/bc5003983, abstract = {For the purpose of near-infrared (NIR) fluorescence and photoacoustic (PA) tomography dual-modular imaging, self-assembly of squaraine (SQ) dyes is constructed in the hydrophobic phospholipid bilayers of liposomes (SQ⊂L) with variable mixing ratios of SQ and phospholipids from 1:500 to 1:10 (w/w). When doping minimal amounts of SQ, molecularly dispersed SQ in bilayers shows remarkable fluorescence. Interesting, the PA signal is enhanced with increase of SQ in the nanoconfined bilayer region, which is attributed to the formation of SQ-based H-aggregates and enhanced thermal conversion efficiency (η). SQ⊂L shows satisfactory chemical and thermal stabilities and photobleaching resistance. SQ⊂L is well-distributed in the cytoplasm of MCF-7 cells and its fluorescence signal remains for 7 days without dramatic quenching owing to the good stability of SQ⊂L. Furthermore, SQ⊂L is subjected to in vivo NIR fluorescence imaging to evaluate the whole-body biodistribution in organ level. Particularly, PA imaging with deeper tissue penetration capability is utilized to investigate the heterogeneous distribution SQ⊂L inside solid tumor. The majority of SQ⊂L are enriched in the area where the blood vessels are generated, implying that the liposomal nanocarriers exhibit lower tumor tissue penetration capability after the vascular leakage. This result is validated by histological examination of tumor tissue in parallel.}, author = {Zhang, Di and Zhao, Ying-Xi and Qiao, Zeng-Ying and Mayerhöffer, Ulrich and Spenst, Peter and Li, Xiao-Jun and Würthner, Frank and Wang, Hao}, journal = {Bioconjugate Chemistry}, keywords = {myown}, note = {PMID: 25370305}, number = 11, pages = {2021-2029}, title = {Nano-Confined Squaraine Dye Assemblies: New Photoacoustic and Near-Infrared Fluorescence Dual-Modular Imaging Probes in Vivo}, volume = 25, year = 2014 }

  %0 Journal Article %1 doi:10.1021/bc5003983 %A Zhang, Di %A Zhao, Ying-Xi %A Qiao, Zeng-Ying %A Mayerhöffer, Ulrich %A Spenst, Peter %A Li, Xiao-Jun %A Würthner, Frank %A Wang, Hao %D 2014 %J Bioconjugate Chemistry %N 11 %P 2021-2029 %R 10.1021/bc5003983 %T Nano-Confined Squaraine Dye Assemblies: New Photoacoustic and Near-Infrared Fluorescence Dual-Modular Imaging Probes in Vivo %U http://dx.doi.org/10.1021/bc5003983 %V 25 %X For the purpose of near-infrared (NIR) fluorescence and photoacoustic (PA) tomography dual-modular imaging, self-assembly of squaraine (SQ) dyes is constructed in the hydrophobic phospholipid bilayers of liposomes (SQ⊂L) with variable mixing ratios of SQ and phospholipids from 1:500 to 1:10 (w/w). When doping minimal amounts of SQ, molecularly dispersed SQ in bilayers shows remarkable fluorescence. Interesting, the PA signal is enhanced with increase of SQ in the nanoconfined bilayer region, which is attributed to the formation of SQ-based H-aggregates and enhanced thermal conversion efficiency (η). SQ⊂L shows satisfactory chemical and thermal stabilities and photobleaching resistance. SQ⊂L is well-distributed in the cytoplasm of MCF-7 cells and its fluorescence signal remains for 7 days without dramatic quenching owing to the good stability of SQ⊂L. Furthermore, SQ⊂L is subjected to in vivo NIR fluorescence imaging to evaluate the whole-body biodistribution in organ level. Particularly, PA imaging with deeper tissue penetration capability is utilized to investigate the heterogeneous distribution SQ⊂L inside solid tumor. The majority of SQ⊂L are enriched in the area where the blood vessels are generated, implying that the liposomal nanocarriers exhibit lower tumor tissue penetration capability after the vascular leakage. This result is validated by histological examination of tumor tissue in parallel.
• Impact of mesoscale order on open-circuit voltage in organic solar cells. Poelking, Carl; Tietze, Max; Elschner, Chris; Olthof, Selina; Hertel, Dirk; Baumeier, Björn; Würthner, Frank; Meerholz, Klaus; Leo, Karl; Andrienko, Denis. 14, p. 434 EP -. 2014.

  Article
  • [ Abstract ]
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  Structural order in organic solar cells is paramount: it reduces energetic disorder, boosts charge and exciton mobilities, and assists exciton splitting. Owing to spatial localization of electronic states, microscopic descriptions of photovoltaic processes tend to overlook the influence of structural features at the mesoscale. Long-range electrostatic interactions nevertheless probe this ordering, making local properties depend on the mesoscopic order. Using a technique developed to address spatially aperiodic excitations in thin films and in bulk, we show how inclusion of mesoscale order resolves the controversy between experimental and theoretical results for the energy-level profile and alignment in a variety of photovoltaic systems, with direct experimental validation. Optimal use of long-range ordering also rationalizes the acceptor–donor–acceptor paradigm for molecular design of donor dyes. We predict open-circuit voltages of planar heterojunction solar cells in excellent agreement with experimental data, based only on crystal structures and interfacial orientation.

  @article{Poelking2014, abstract = {Structural order in organic solar cells is paramount: it reduces energetic disorder, boosts charge and exciton mobilities, and assists exciton splitting. Owing to spatial localization of electronic states, microscopic descriptions of photovoltaic processes tend to overlook the influence of structural features at the mesoscale. Long-range electrostatic interactions nevertheless probe this ordering, making local properties depend on the mesoscopic order. Using a technique developed to address spatially aperiodic excitations in thin films and in bulk, we show how inclusion of mesoscale order resolves the controversy between experimental and theoretical results for the energy-level profile and alignment in a variety of photovoltaic systems, with direct experimental validation. Optimal use of long-range ordering also rationalizes the acceptor–donor–acceptor paradigm for molecular design of donor dyes. We predict open-circuit voltages of planar heterojunction solar cells in excellent agreement with experimental data, based only on crystal structures and interfacial orientation.}, author = {Poelking, Carl and Tietze, Max and Elschner, Chris and Olthof, Selina and Hertel, Dirk and Baumeier, Björn and Würthner, Frank and Meerholz, Klaus and Leo, Karl and Andrienko, Denis}, keywords = {myown}, month = 12, note = {Article}, pages = {434 EP -}, publisher = {Nature Publishing Group SN -}, title = {Impact of mesoscale order on open-circuit voltage in organic solar cells}, volume = 14, year = 2014 }

  %0 Journal Article %1 Poelking2014 %A Poelking, Carl %A Tietze, Max %A Elschner, Chris %A Olthof, Selina %A Hertel, Dirk %A Baumeier, Björn %A Würthner, Frank %A Meerholz, Klaus %A Leo, Karl %A Andrienko, Denis %D 2014 %I Nature Publishing Group SN - %P 434 EP - %T Impact of mesoscale order on open-circuit voltage in organic solar cells %U http://dx.doi.org/10.1038/nmat4167 %V 14 %X Structural order in organic solar cells is paramount: it reduces energetic disorder, boosts charge and exciton mobilities, and assists exciton splitting. Owing to spatial localization of electronic states, microscopic descriptions of photovoltaic processes tend to overlook the influence of structural features at the mesoscale. Long-range electrostatic interactions nevertheless probe this ordering, making local properties depend on the mesoscopic order. Using a technique developed to address spatially aperiodic excitations in thin films and in bulk, we show how inclusion of mesoscale order resolves the controversy between experimental and theoretical results for the energy-level profile and alignment in a variety of photovoltaic systems, with direct experimental validation. Optimal use of long-range ordering also rationalizes the acceptor–donor–acceptor paradigm for molecular design of donor dyes. We predict open-circuit voltages of planar heterojunction solar cells in excellent agreement with experimental data, based only on crystal structures and interfacial orientation.
• An organogelator design without solubilizing side chains by backbone contortion of a perylene bisimide pigment. Xie, Zengqi; Stepanenko, Vladimir; Fimmel, Benjamin; Würthner, Frank. In Mater. Horiz., 1(3), pp. 355–359. 2014.
  • [ Abstract ]
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  Here we report a perylene bisimide (PBI) based gelator molecule that contains neither a long alkyl chain nor any other solubilizing group which are considered to be essential moieties of organogelators. Instead, the solubility of the newly designed PBI gelator 4a is imparted by a contorted aromatic core. Its self-assembly into highly fluorescent one-dimensional nanostructures is directed by H-bonding, affording extremely low critical gelation concentrations (CGCs) below 0.1 wt%.

  @article{C3MH00159H, abstract = {Here we report a perylene bisimide (PBI) based gelator molecule that contains neither a long alkyl chain nor any other solubilizing group which are considered to be essential moieties of organogelators. Instead{,} the solubility of the newly designed PBI gelator 4a is imparted by a contorted aromatic core. Its self-assembly into highly fluorescent one-dimensional nanostructures is directed by H-bonding{,} affording extremely low critical gelation concentrations (CGCs) below 0.1 wt%.}, author = {Xie, Zengqi and Stepanenko, Vladimir and Fimmel, Benjamin and Würthner, Frank}, journal = {Mater. Horiz.}, keywords = {myown}, number = 3, pages = {355-359}, publisher = {The Royal Society of Chemistry}, title = {An organogelator design without solubilizing side chains by backbone contortion of a perylene bisimide pigment}, volume = 1, year = 2014 }

  %0 Journal Article %1 C3MH00159H %A Xie, Zengqi %A Stepanenko, Vladimir %A Fimmel, Benjamin %A Würthner, Frank %D 2014 %I The Royal Society of Chemistry %J Mater. Horiz. %N 3 %P 355-359 %R 10.1039/C3MH00159H %T An organogelator design without solubilizing side chains by backbone contortion of a perylene bisimide pigment %U http://dx.doi.org/10.1039/C3MH00159H %V 1 %X Here we report a perylene bisimide (PBI) based gelator molecule that contains neither a long alkyl chain nor any other solubilizing group which are considered to be essential moieties of organogelators. Instead, the solubility of the newly designed PBI gelator 4a is imparted by a contorted aromatic core. Its self-assembly into highly fluorescent one-dimensional nanostructures is directed by H-bonding, affording extremely low critical gelation concentrations (CGCs) below 0.1 wt%.
• High-Performance Organic Thin-Film Transistors of J-Stacked Squaraine Dyes. Gsänger, Marcel; Kirchner, Eva; Stolte, Matthias; Burschka, Christian; Stepanenko, Vladimir; Pflaum, Jens; Würthner, Frank. In J. Am. Chem. Soc., 136(6), pp. 2351–2362. 2014.

  PMID: 24432873
  • [ Abstract ]
  • [ BibTeX ]
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  We have synthesized a series of dipolar squaraine dyes that contain dicyanovinyl groups as acceptor and benzannulated five-membered ring heterocycles with alkyl chains of varied length as donor moieties. Based on these squaraines, thin-film transistors (TFT) were fabricated by spin coating and solution shearing. Moreover, with one of these squaraine derivatives vacuum-deposited TFTs were prepared as well. Our detailed studies revealed that the transistor performance of the present series of squaraines is strongly dependent on their structural features as well as on the processing method of thin films. Thus, solution-sheared OTFTs of selenium squaraine bearing dodecyl substituents (denoted as Se-SQ-C12) performed best with a maximum hole mobility of 0.45 cm2 V–1 s–1, which is by far the highest value yet reported for OTFTs based on squaraines. This value was even surpassed by vacuum-deposited thin films of n-butyl-substituted selenium squaraine Se-SQ-C4, the only sublimable compound in this series, exhibiting a record hole mobility of 1.3 cm2 V–1 s–1. Furthermore, we have investigated the morphology of the thin films and the molecular packing of these squaraine dyes by optical spectroscopy, atomic force microscopy, and X-ray diffraction. These studies revealed a relationship between the molecular structure, packing motif, thin-film morphology, and transistor performance of the squaraine dyes. From the supramolecular point of view two packing features discovered in the single crystal structure of Se-SQ-C8 are of particular interest with regard to the structure–functionality relationship: The first is the slipped and antiparallel π-stacking motif which ensures cancellation of the molecules’ dipole moments and J-type absorption band formation in thin films. The second is the presence of CN···Se noncovalent bonds which show similarities to the more common halogen-bonding interactions and which interconnect the individual one-dimensional slipped π-stacks, thus leading to two-dimensional percolation pathways along the source–drain direction.

  @article{doi:10.1021/ja409496r, abstract = {We have synthesized a series of dipolar squaraine dyes that contain dicyanovinyl groups as acceptor and benzannulated five-membered ring heterocycles with alkyl chains of varied length as donor moieties. Based on these squaraines, thin-film transistors (TFT) were fabricated by spin coating and solution shearing. Moreover, with one of these squaraine derivatives vacuum-deposited TFTs were prepared as well. Our detailed studies revealed that the transistor performance of the present series of squaraines is strongly dependent on their structural features as well as on the processing method of thin films. Thus, solution-sheared OTFTs of selenium squaraine bearing dodecyl substituents (denoted as Se-SQ-C12) performed best with a maximum hole mobility of 0.45 cm2 V–1 s–1, which is by far the highest value yet reported for OTFTs based on squaraines. This value was even surpassed by vacuum-deposited thin films of n-butyl-substituted selenium squaraine Se-SQ-C4, the only sublimable compound in this series, exhibiting a record hole mobility of 1.3 cm2 V–1 s–1. Furthermore, we have investigated the morphology of the thin films and the molecular packing of these squaraine dyes by optical spectroscopy, atomic force microscopy, and X-ray diffraction. These studies revealed a relationship between the molecular structure, packing motif, thin-film morphology, and transistor performance of the squaraine dyes. From the supramolecular point of view two packing features discovered in the single crystal structure of Se-SQ-C8 are of particular interest with regard to the structure–functionality relationship: The first is the slipped and antiparallel π-stacking motif which ensures cancellation of the molecules’ dipole moments and J-type absorption band formation in thin films. The second is the presence of CN···Se noncovalent bonds which show similarities to the more common halogen-bonding interactions and which interconnect the individual one-dimensional slipped π-stacks, thus leading to two-dimensional percolation pathways along the source–drain direction.}, author = {Gsänger, Marcel and Kirchner, Eva and Stolte, Matthias and Burschka, Christian and Stepanenko, Vladimir and Pflaum, Jens and Würthner, Frank}, journal = {J. Am. Chem. Soc.}, keywords = {myown}, note = {PMID: 24432873}, number = 6, pages = {2351-2362}, title = {High-Performance Organic Thin-Film Transistors of J-Stacked Squaraine Dyes}, volume = 136, year = 2014 }

  %0 Journal Article %1 doi:10.1021/ja409496r %A Gsänger, Marcel %A Kirchner, Eva %A Stolte, Matthias %A Burschka, Christian %A Stepanenko, Vladimir %A Pflaum, Jens %A Würthner, Frank %D 2014 %J J. Am. Chem. Soc. %N 6 %P 2351-2362 %R 10.1021/ja409496r %T High-Performance Organic Thin-Film Transistors of J-Stacked Squaraine Dyes %U http://dx.doi.org/10.1021/ja409496r %V 136 %X We have synthesized a series of dipolar squaraine dyes that contain dicyanovinyl groups as acceptor and benzannulated five-membered ring heterocycles with alkyl chains of varied length as donor moieties. Based on these squaraines, thin-film transistors (TFT) were fabricated by spin coating and solution shearing. Moreover, with one of these squaraine derivatives vacuum-deposited TFTs were prepared as well. Our detailed studies revealed that the transistor performance of the present series of squaraines is strongly dependent on their structural features as well as on the processing method of thin films. Thus, solution-sheared OTFTs of selenium squaraine bearing dodecyl substituents (denoted as Se-SQ-C12) performed best with a maximum hole mobility of 0.45 cm2 V–1 s–1, which is by far the highest value yet reported for OTFTs based on squaraines. This value was even surpassed by vacuum-deposited thin films of n-butyl-substituted selenium squaraine Se-SQ-C4, the only sublimable compound in this series, exhibiting a record hole mobility of 1.3 cm2 V–1 s–1. Furthermore, we have investigated the morphology of the thin films and the molecular packing of these squaraine dyes by optical spectroscopy, atomic force microscopy, and X-ray diffraction. These studies revealed a relationship between the molecular structure, packing motif, thin-film morphology, and transistor performance of the squaraine dyes. From the supramolecular point of view two packing features discovered in the single crystal structure of Se-SQ-C8 are of particular interest with regard to the structure–functionality relationship: The first is the slipped and antiparallel π-stacking motif which ensures cancellation of the molecules’ dipole moments and J-type absorption band formation in thin films. The second is the presence of CN···Se noncovalent bonds which show similarities to the more common halogen-bonding interactions and which interconnect the individual one-dimensional slipped π-stacks, thus leading to two-dimensional percolation pathways along the source–drain direction.
• Impact of Molecular Dipole Moments on Fermi Level Pinning in Thin Films. Winkler, Stefanie; Frisch, Johannes; Amsalem, Patrick; Krause, Stefan; Timpel, Melanie; Stolte, Matthias; Würthner, Frank; Koch, Norbert. In J. Phys. Chem. C., 118(22), pp. 11731–11737. 2014.
  • [ Abstract ]
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  A series of merocyanine dyes with a wide range of molecular dipole moments were deposited on metal oxides covering a wide work function (Φ) range (2.3 to 7.0 eV), and the energy level alignment at these interfaces was studied with photoelectron spectroscopy. We find that a preferential orientation of the merocyanines and their dipoles in the monolayer systematically lowers Φ of the oxides such that Fermi-level (EF) pinning at the highest occupied molecular level of the merocyanines only occurs for very high Φ oxides (≥6 eV). Correspondingly, pinning at the electron affinity level can readily be achieved also with moderate oxide Φ, e.g., for indium tin oxide, and electron transfer between the merocyanines to these oxides can proceed readily. Noteworthy, the EF-pinning behavior and the associated Φ values seem independent of the molecular dipole moment magnitude, most likely due to the self-limiting effect of Φ as soon as the pinning regime is reached.

  @article{doi:10.1021/jp5021615, abstract = {A series of merocyanine dyes with a wide range of molecular dipole moments were deposited on metal oxides covering a wide work function (Φ) range (2.3 to 7.0 eV), and the energy level alignment at these interfaces was studied with photoelectron spectroscopy. We find that a preferential orientation of the merocyanines and their dipoles in the monolayer systematically lowers Φ of the oxides such that Fermi-level (EF) pinning at the highest occupied molecular level of the merocyanines only occurs for very high Φ oxides (≥6 eV). Correspondingly, pinning at the electron affinity level can readily be achieved also with moderate oxide Φ, e.g., for indium tin oxide, and electron transfer between the merocyanines to these oxides can proceed readily. Noteworthy, the EF-pinning behavior and the associated Φ values seem independent of the molecular dipole moment magnitude, most likely due to the self-limiting effect of Φ as soon as the pinning regime is reached.}, author = {Winkler, Stefanie and Frisch, Johannes and Amsalem, Patrick and Krause, Stefan and Timpel, Melanie and Stolte, Matthias and Würthner, Frank and Koch, Norbert}, journal = {J. Phys. Chem. C.}, keywords = {myown}, number = 22, pages = {11731-11737}, title = {Impact of Molecular Dipole Moments on Fermi Level Pinning in Thin Films}, volume = 118, year = 2014 }

  %0 Journal Article %1 doi:10.1021/jp5021615 %A Winkler, Stefanie %A Frisch, Johannes %A Amsalem, Patrick %A Krause, Stefan %A Timpel, Melanie %A Stolte, Matthias %A Würthner, Frank %A Koch, Norbert %D 2014 %J J. Phys. Chem. C. %N 22 %P 11731-11737 %R 10.1021/jp5021615 %T Impact of Molecular Dipole Moments on Fermi Level Pinning in Thin Films %U http://dx.doi.org/10.1021/jp5021615 %V 118 %X A series of merocyanine dyes with a wide range of molecular dipole moments were deposited on metal oxides covering a wide work function (Φ) range (2.3 to 7.0 eV), and the energy level alignment at these interfaces was studied with photoelectron spectroscopy. We find that a preferential orientation of the merocyanines and their dipoles in the monolayer systematically lowers Φ of the oxides such that Fermi-level (EF) pinning at the highest occupied molecular level of the merocyanines only occurs for very high Φ oxides (≥6 eV). Correspondingly, pinning at the electron affinity level can readily be achieved also with moderate oxide Φ, e.g., for indium tin oxide, and electron transfer between the merocyanines to these oxides can proceed readily. Noteworthy, the EF-pinning behavior and the associated Φ values seem independent of the molecular dipole moment magnitude, most likely due to the self-limiting effect of Φ as soon as the pinning regime is reached.
• Photocontrol Over Self-Assembled Nanostructures of π–π Stacked Dyes Supported by the Parallel Conformer of Diarylethene. Yagai, Shiki; Iwai, Kazunori; Yamauchi, Mitsuaki; Karatsu, Takashi; Kitamura, Akihide; Uemura, Shinobu; Morimoto, Masakazu; Wang, Hao; Würthner, Frank. In Angew. Chem. Int. Ed., 53(10), pp. 2602–2606. 2014.
  • [ Abstract ]
  • [ BibTeX ]
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  • [ DOI ]
  Diarylethenes (DAEs) have rarely been used in the design of photoresponsive supramolecular assemblies with a well-defined morphology transition owing to rather small structural changes upon photoisomerization. A supramolecular design based on the parallel conformation of DAEs enables the construction of photoresponsive dye assemblies that undergo remarkable nanomorphology transitions. The cooperative stacking of perylene bisimide (PBI) dyes was used to stabilize the parallel conformer of DAE through complementary hydrogen bonds. Atomic force microscopy, UV/Vis spectroscopy, and molecular modeling revealed that our DAE and PBI building blocks coassembled in nonpolar solvent to form well-defined helical nanofibers featuring J-type dimers of PBI dyes. Upon irradiating the coassembly solution with UV and visible light in turn, a reversible morphology change between nanofibers and nanoparticles was observed. This system involves the generation of a new self-assembly pathway by means of photocontrol.

  @article{ANIE:ANIE201310773, abstract = {Diarylethenes (DAEs) have rarely been used in the design of photoresponsive supramolecular assemblies with a well-defined morphology transition owing to rather small structural changes upon photoisomerization. A supramolecular design based on the parallel conformation of DAEs enables the construction of photoresponsive dye assemblies that undergo remarkable nanomorphology transitions. The cooperative stacking of perylene bisimide (PBI) dyes was used to stabilize the parallel conformer of DAE through complementary hydrogen bonds. Atomic force microscopy, UV/Vis spectroscopy, and molecular modeling revealed that our DAE and PBI building blocks coassembled in nonpolar solvent to form well-defined helical nanofibers featuring J-type dimers of PBI dyes. Upon irradiating the coassembly solution with UV and visible light in turn, a reversible morphology change between nanofibers and nanoparticles was observed. This system involves the generation of a new self-assembly pathway by means of photocontrol.}, author = {Yagai, Shiki and Iwai, Kazunori and Yamauchi, Mitsuaki and Karatsu, Takashi and Kitamura, Akihide and Uemura, Shinobu and Morimoto, Masakazu and Wang, Hao and Würthner, Frank}, journal = {Angew. Chem. Int. Ed.}, keywords = {myown}, number = 10, pages = {2602–2606}, publisher = {WILEY-VCH Verlag}, title = {Photocontrol Over Self-Assembled Nanostructures of π–π Stacked Dyes Supported by the Parallel Conformer of Diarylethene}, volume = 53, year = 2014 }

  %0 Journal Article %1 ANIE:ANIE201310773 %A Yagai, Shiki %A Iwai, Kazunori %A Yamauchi, Mitsuaki %A Karatsu, Takashi %A Kitamura, Akihide %A Uemura, Shinobu %A Morimoto, Masakazu %A Wang, Hao %A Würthner, Frank %D 2014 %I WILEY-VCH Verlag %J Angew. Chem. Int. Ed. %N 10 %P 2602--2606 %R 10.1002/anie.201310773 %T Photocontrol Over Self-Assembled Nanostructures of π–π Stacked Dyes Supported by the Parallel Conformer of Diarylethene %U http://dx.doi.org/10.1002/anie.201310773 %V 53 %X Diarylethenes (DAEs) have rarely been used in the design of photoresponsive supramolecular assemblies with a well-defined morphology transition owing to rather small structural changes upon photoisomerization. A supramolecular design based on the parallel conformation of DAEs enables the construction of photoresponsive dye assemblies that undergo remarkable nanomorphology transitions. The cooperative stacking of perylene bisimide (PBI) dyes was used to stabilize the parallel conformer of DAE through complementary hydrogen bonds. Atomic force microscopy, UV/Vis spectroscopy, and molecular modeling revealed that our DAE and PBI building blocks coassembled in nonpolar solvent to form well-defined helical nanofibers featuring J-type dimers of PBI dyes. Upon irradiating the coassembly solution with UV and visible light in turn, a reversible morphology change between nanofibers and nanoparticles was observed. This system involves the generation of a new self-assembly pathway by means of photocontrol.
• Hierarchical Growth of Fluorescent Dye Aggregates in Water by Fusion of Segmented Nanostructures. Zhang, Xin; Görl, Daniel; Stepanenko, Vladimir; Würthner, Frank. In Angew. Chem. Int. Ed., 53(5), pp. 1270–1274. 2014.
  • [ Abstract ]
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  Dye aggregates are becoming increasingly attractive for diverse applications, in particular as organic electronic and sensor materials. However, the growth processes of such aggregates from molecular to small assemblies up to nanostructures is still not properly understood, limiting the design of materials’ functional properties. Here we elucidate the supramolecular growth process for an outstanding class of functional dyes, perylene bisimides (PBIs), by transmission electron microscopy (TEM), cryogenic scanning electron microscopy (cryo-SEM), and atomic force microscopy (AFM). Our studies reveal a sequential growth of amphiphilic PBI dyes from nanorods into nanoribbons in water by fusion and fission processes. More intriguingly, the fluorescence observed for higher hierarchical order nanoribbons was enhanced relative to that of nanorods. Our results provide insight into the relationship between molecular, morphological, and functional properties of self-assembled organic materials.

  @article{ANIE:ANIE201308963, abstract = {Dye aggregates are becoming increasingly attractive for diverse applications, in particular as organic electronic and sensor materials. However, the growth processes of such aggregates from molecular to small assemblies up to nanostructures is still not properly understood, limiting the design of materials’ functional properties. Here we elucidate the supramolecular growth process for an outstanding class of functional dyes, perylene bisimides (PBIs), by transmission electron microscopy (TEM), cryogenic scanning electron microscopy (cryo-SEM), and atomic force microscopy (AFM). Our studies reveal a sequential growth of amphiphilic PBI dyes from nanorods into nanoribbons in water by fusion and fission processes. More intriguingly, the fluorescence observed for higher hierarchical order nanoribbons was enhanced relative to that of nanorods. Our results provide insight into the relationship between molecular, morphological, and functional properties of self-assembled organic materials.}, author = {Zhang, Xin and Görl, Daniel and Stepanenko, Vladimir and Würthner, Frank}, journal = {Angew. Chem. Int. Ed.}, keywords = {myown}, number = 5, pages = {1270–1274}, publisher = {WILEY-VCH Verlag}, title = {Hierarchical Growth of Fluorescent Dye Aggregates in Water by Fusion of Segmented Nanostructures}, volume = 53, year = 2014 }

  %0 Journal Article %1 ANIE:ANIE201308963 %A Zhang, Xin %A Görl, Daniel %A Stepanenko, Vladimir %A Würthner, Frank %D 2014 %I WILEY-VCH Verlag %J Angew. Chem. Int. Ed. %N 5 %P 1270--1274 %R 10.1002/anie.201308963 %T Hierarchical Growth of Fluorescent Dye Aggregates in Water by Fusion of Segmented Nanostructures %U http://dx.doi.org/10.1002/anie.201308963 %V 53 %X Dye aggregates are becoming increasingly attractive for diverse applications, in particular as organic electronic and sensor materials. However, the growth processes of such aggregates from molecular to small assemblies up to nanostructures is still not properly understood, limiting the design of materials’ functional properties. Here we elucidate the supramolecular growth process for an outstanding class of functional dyes, perylene bisimides (PBIs), by transmission electron microscopy (TEM), cryogenic scanning electron microscopy (cryo-SEM), and atomic force microscopy (AFM). Our studies reveal a sequential growth of amphiphilic PBI dyes from nanorods into nanoribbons in water by fusion and fission processes. More intriguingly, the fluorescence observed for higher hierarchical order nanoribbons was enhanced relative to that of nanorods. Our results provide insight into the relationship between molecular, morphological, and functional properties of self-assembled organic materials.
• Supramolecular polymerization: Living it up. Würthner, Frank. In Nat Chem, 6(3), pp. 171–173. 2014.
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  @article{wurthner2014supramolecular, author = {Würthner, Frank}, journal = {Nat Chem}, keywords = {myown}, month = {03}, number = 3, pages = {171–173}, publisher = {Nature Publishing Group, a division of Macmillan Publishers Limited. All Rights Reserved.}, title = {Supramolecular polymerization: Living it up}, volume = 6, year = 2014 }

  %0 Journal Article %1 wurthner2014supramolecular %A Würthner, Frank %D 2014 %I Nature Publishing Group, a division of Macmillan Publishers Limited. All Rights Reserved. %J Nat Chem %N 3 %P 171--173 %T Supramolecular polymerization: Living it up %U http://dx.doi.org/10.1038/nchem.1863 %V 6
• Spectroscopic Demonstration of Exciton Dynamics and Excimer Formation in a Sterically Controlled Perylene Bisimide Dimer Aggregate. Son, Minjung; Park, Kyu Hyung; Shao, Changzhun; Würthner, Frank; Kim, Dongho. In J. Phys. Chem. Lett., 5(20), pp. 3601–3607. 2014.

  PMID: 26278616
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  Although it is commonly known that H-type PBI aggregates give rise to a broad, red-shifted excimer fluorescence with considerably longer fluorescence lifetimes than observed for the monomers, the underlying mechanisms of excimer formation and other relevant exciton dynamics in such π-stacked systems are still far from being understood. In this context, we demonstrate a thorough spectroscopic investigation on the exciton relaxation pathways, including excimer formation, in a perylene-3,4:9,10-bis(dicarboximide) (PBI) dimer aggregate 1 by using time-resolved fluorescence and transient absorption spectroscopy combined with excitation-power and polarization dependence. It was found that the excited dimer formation process followed by structural rearrangement is approximately two times faster than observed within larger PBI aggregates. Excitation-power-dependent transient absorption decay profiles revealed the fully delocalized nature of excitons in the dimer as opposed to larger stacks.

  @article{doi:10.1021/jz501953a, abstract = {Although it is commonly known that H-type PBI aggregates give rise to a broad, red-shifted excimer fluorescence with considerably longer fluorescence lifetimes than observed for the monomers, the underlying mechanisms of excimer formation and other relevant exciton dynamics in such π-stacked systems are still far from being understood. In this context, we demonstrate a thorough spectroscopic investigation on the exciton relaxation pathways, including excimer formation, in a perylene-3,4:9,10-bis(dicarboximide) (PBI) dimer aggregate 1 by using time-resolved fluorescence and transient absorption spectroscopy combined with excitation-power and polarization dependence. It was found that the excited dimer formation process followed by structural rearrangement is approximately two times faster than observed within larger PBI aggregates. Excitation-power-dependent transient absorption decay profiles revealed the fully delocalized nature of excitons in the dimer as opposed to larger stacks.}, author = {Son, Minjung and Park, Kyu Hyung and Shao, Changzhun and Würthner, Frank and Kim, Dongho}, journal = {J. Phys. Chem. Lett.}, keywords = {myown}, note = {PMID: 26278616}, number = 20, pages = {3601-3607}, title = {Spectroscopic Demonstration of Exciton Dynamics and Excimer Formation in a Sterically Controlled Perylene Bisimide Dimer Aggregate}, volume = 5, year = 2014 }

  %0 Journal Article %1 doi:10.1021/jz501953a %A Son, Minjung %A Park, Kyu Hyung %A Shao, Changzhun %A Würthner, Frank %A Kim, Dongho %D 2014 %J J. Phys. Chem. Lett. %N 20 %P 3601-3607 %R 10.1021/jz501953a %T Spectroscopic Demonstration of Exciton Dynamics and Excimer Formation in a Sterically Controlled Perylene Bisimide Dimer Aggregate %U /brokenurl# http://dx.doi.org/10.1021/jz501953a %V 5 %X Although it is commonly known that H-type PBI aggregates give rise to a broad, red-shifted excimer fluorescence with considerably longer fluorescence lifetimes than observed for the monomers, the underlying mechanisms of excimer formation and other relevant exciton dynamics in such π-stacked systems are still far from being understood. In this context, we demonstrate a thorough spectroscopic investigation on the exciton relaxation pathways, including excimer formation, in a perylene-3,4:9,10-bis(dicarboximide) (PBI) dimer aggregate 1 by using time-resolved fluorescence and transient absorption spectroscopy combined with excitation-power and polarization dependence. It was found that the excited dimer formation process followed by structural rearrangement is approximately two times faster than observed within larger PBI aggregates. Excitation-power-dependent transient absorption decay profiles revealed the fully delocalized nature of excitons in the dimer as opposed to larger stacks.
• Reconstruction of the Molecular Structure of a Multichromophoric System Using Single-Molecule Defocused Wide-Field Imaging. Ham, Sujin; Yang, Jaesung; Schlosser, Felix; Würthner, Frank; Kim, Dongho. In J. Phys. Chem. Lett., 5(16), pp. 2830–2835. 2014.

  PMID: 26278086
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  Single-molecule defocused wide-field imaging (DWFI) has been demonstrated to be useful to determine molecular structure parameters, such as the orientations of transition dipole moments and the angular relationships between chromophores in multichromophoric molecular systems. For a series of acetylene-linked perylene bisimide (PBI) macrocycles with different ring size comprising three to six PBI dyes, we reconstructed the molecular structure of the multichromophoric system using DWFI method. Furthermore, we revealed that the structural heterogeneities and distortions depend on the ring size. Our findings illustrate the use of DWFI to gain deeper insight into the structure–property relationships of artificial light-harvesting molecular systems.

  @article{doi:10.1021/jz501233d, abstract = {Single-molecule defocused wide-field imaging (DWFI) has been demonstrated to be useful to determine molecular structure parameters, such as the orientations of transition dipole moments and the angular relationships between chromophores in multichromophoric molecular systems. For a series of acetylene-linked perylene bisimide (PBI) macrocycles with different ring size comprising three to six PBI dyes, we reconstructed the molecular structure of the multichromophoric system using DWFI method. Furthermore, we revealed that the structural heterogeneities and distortions depend on the ring size. Our findings illustrate the use of DWFI to gain deeper insight into the structure–property relationships of artificial light-harvesting molecular systems.}, author = {Ham, Sujin and Yang, Jaesung and Schlosser, Felix and Würthner, Frank and Kim, Dongho}, journal = {J. Phys. Chem. Lett.}, keywords = {myown}, note = {PMID: 26278086}, number = 16, pages = {2830-2835}, title = {Reconstruction of the Molecular Structure of a Multichromophoric System Using Single-Molecule Defocused Wide-Field Imaging}, volume = 5, year = 2014 }

  %0 Journal Article %1 doi:10.1021/jz501233d %A Ham, Sujin %A Yang, Jaesung %A Schlosser, Felix %A Würthner, Frank %A Kim, Dongho %D 2014 %J J. Phys. Chem. Lett. %N 16 %P 2830-2835 %R 10.1021/jz501233d %T Reconstruction of the Molecular Structure of a Multichromophoric System Using Single-Molecule Defocused Wide-Field Imaging %U http://dx.doi.org/10.1021/jz501233d %V 5 %X Single-molecule defocused wide-field imaging (DWFI) has been demonstrated to be useful to determine molecular structure parameters, such as the orientations of transition dipole moments and the angular relationships between chromophores in multichromophoric molecular systems. For a series of acetylene-linked perylene bisimide (PBI) macrocycles with different ring size comprising three to six PBI dyes, we reconstructed the molecular structure of the multichromophoric system using DWFI method. Furthermore, we revealed that the structural heterogeneities and distortions depend on the ring size. Our findings illustrate the use of DWFI to gain deeper insight into the structure–property relationships of artificial light-harvesting molecular systems.
• Theoretical Analysis of the Relaxation Dynamics in Perylene Bisimide Dimers Excited by Femtosecond Laser Pulses. Schubert, Alexander; Falge, Mirjam; Kess, Martin; Settels, Volker; Lochbrunner, Stefan; Strunz, Walter T.; Würthner, Frank; Engels, Bernd; Engel, Volker. In J. Phys. Chem. A, 118(8), pp. 1403–1412. 2014.

  PMID: 24475775
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  We present a model for the relaxation dynamics in perylene bisimide dimers, which is based on ab initio electronic structure and quantum dynamics calculations including effects of dissipation. The excited-state dynamics proceeds via a mixing of electronic states of local Frenkel and charge-transfer characters, which becomes effective upon a small distortion of the dimer geometry. In this way, it is possible to explain the fast depopulation of the photoexcited state, which we characterize by femtosecond transient absorption measurements. The combined theoretical and experimental analysis hints at a trapping mechanism, which involves nonadiabatic and dissipative dynamics in an excited-state vibronic manifold and provides an atomistic picture that might prove valuable for future design of photovoltaic materials.

  @article{doi:10.1021/jp412166a, abstract = {We present a model for the relaxation dynamics in perylene bisimide dimers, which is based on ab initio electronic structure and quantum dynamics calculations including effects of dissipation. The excited-state dynamics proceeds via a mixing of electronic states of local Frenkel and charge-transfer characters, which becomes effective upon a small distortion of the dimer geometry. In this way, it is possible to explain the fast depopulation of the photoexcited state, which we characterize by femtosecond transient absorption measurements. The combined theoretical and experimental analysis hints at a trapping mechanism, which involves nonadiabatic and dissipative dynamics in an excited-state vibronic manifold and provides an atomistic picture that might prove valuable for future design of photovoltaic materials.}, author = {Schubert, Alexander and Falge, Mirjam and Kess, Martin and Settels, Volker and Lochbrunner, Stefan and Strunz, Walter T. and Würthner, Frank and Engels, Bernd and Engel, Volker}, journal = {J. Phys. Chem. A}, keywords = {myown}, note = {PMID: 24475775}, number = 8, pages = {1403-1412}, title = {Theoretical Analysis of the Relaxation Dynamics in Perylene Bisimide Dimers Excited by Femtosecond Laser Pulses}, volume = 118, year = 2014 }

  %0 Journal Article %1 doi:10.1021/jp412166a %A Schubert, Alexander %A Falge, Mirjam %A Kess, Martin %A Settels, Volker %A Lochbrunner, Stefan %A Strunz, Walter T. %A Würthner, Frank %A Engels, Bernd %A Engel, Volker %D 2014 %J J. Phys. Chem. A %N 8 %P 1403-1412 %R 10.1021/jp412166a %T Theoretical Analysis of the Relaxation Dynamics in Perylene Bisimide Dimers Excited by Femtosecond Laser Pulses %U http://dx.doi.org/10.1021/jp412166a %V 118 %X We present a model for the relaxation dynamics in perylene bisimide dimers, which is based on ab initio electronic structure and quantum dynamics calculations including effects of dissipation. The excited-state dynamics proceeds via a mixing of electronic states of local Frenkel and charge-transfer characters, which becomes effective upon a small distortion of the dimer geometry. In this way, it is possible to explain the fast depopulation of the photoexcited state, which we characterize by femtosecond transient absorption measurements. The combined theoretical and experimental analysis hints at a trapping mechanism, which involves nonadiabatic and dissipative dynamics in an excited-state vibronic manifold and provides an atomistic picture that might prove valuable for future design of photovoltaic materials.
• Single Lévy States–Disorder Induced Energy Funnels in Molecular Aggregates. Merdasa, Aboma; Jiménez, Ángel J.; Camacho, Rafael; Meyer, Matthias; Würthner, Frank; Scheblykin, Ivan G. In Nano Letters, 14(12), pp. 6774–6781. 2014.

  PMID: 25349900
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  Using fluorescence super-resolution microscopy we studied simultaneous spectral, spatial localization, and blinking behavior of individual 1D J-aggregates. Excitons migrating 100 nm are funneled to a trap appearing as an additional red-shifted blinking fluorescence band. We propose that the trap is a Frenkel exciton state formed much below the main exciton band edge due to an environmentally induced heavy-tailed Lévy disorder. This points to disorder engineering as a new avenue in controlling light-harvesting in molecular ensembles

  @article{doi:10.1021/nl5021188, abstract = {Using fluorescence super-resolution microscopy we studied simultaneous spectral, spatial localization, and blinking behavior of individual 1D J-aggregates. Excitons migrating 100 nm are funneled to a trap appearing as an additional red-shifted blinking fluorescence band. We propose that the trap is a Frenkel exciton state formed much below the main exciton band edge due to an environmentally induced heavy-tailed Lévy disorder. This points to disorder engineering as a new avenue in controlling light-harvesting in molecular ensembles}, author = {Merdasa, Aboma and Jiménez, Ángel J. and Camacho, Rafael and Meyer, Matthias and Würthner, Frank and Scheblykin, Ivan G.}, journal = {Nano Letters}, keywords = {myown}, note = {PMID: 25349900}, number = 12, pages = {6774-6781}, title = {Single Lévy States–Disorder Induced Energy Funnels in Molecular Aggregates}, volume = 14, year = 2014 }

  %0 Journal Article %1 doi:10.1021/nl5021188 %A Merdasa, Aboma %A Jiménez, Ángel J. %A Camacho, Rafael %A Meyer, Matthias %A Würthner, Frank %A Scheblykin, Ivan G. %D 2014 %J Nano Letters %N 12 %P 6774-6781 %R 10.1021/nl5021188 %T Single Lévy States–Disorder Induced Energy Funnels in Molecular Aggregates %U http://dx.doi.org/10.1021/nl5021188 %V 14 %X Using fluorescence super-resolution microscopy we studied simultaneous spectral, spatial localization, and blinking behavior of individual 1D J-aggregates. Excitons migrating 100 nm are funneled to a trap appearing as an additional red-shifted blinking fluorescence band. We propose that the trap is a Frenkel exciton state formed much below the main exciton band edge due to an environmentally induced heavy-tailed Lévy disorder. This points to disorder engineering as a new avenue in controlling light-harvesting in molecular ensembles
• Functional bisimide dyes bound via electrostatic interactions to oxide nanostructures generated by AFM lithography. Baumgärtel, T.; Rehm, S.; Würthner, F.; von Borczyskowski, C.; Graaf, H. In Applied Surface Science, 318(Supplement C), pp. 51–58. 2014.

  NANOTR9, 9th Nanoscience and Nanotechnology Conference Special Issue
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  Abstract Silicon oxide nanostructures have been functionalized by selective binding of a positively charged bisimide dye derivative. The structures were prepared by AFM nanolithography via local anodic oxidation (LAO) of dodecyl-terminated silicon and are negatively charged due to the production process. Therefore cationic spermine-functionalized perylene bisimide (sf-PBI) molecules can be bound to the structures by electrostatic interactions. The assembly of the sf-PBI units on the LAO nanostructures is verified by AFM height measurements and means of fluorescence microscopy. Emission spectra from the dye-functionalized oxide show that the molecules are able to form excimers. These excimers are characterized by a broad and featureless red-shifted emission band and an increased excited state life time. In contrast to the emission of sf-PBI films on uncharged silicon oxide, the excimer emission was found to decrease strongly low temperatures. This might be explained by a very tight binding due to the electrostatic attraction of the molecules to the LAO oxide.

  @article{BAUMGARTEL201451, abstract = {Abstract Silicon oxide nanostructures have been functionalized by selective binding of a positively charged bisimide dye derivative. The structures were prepared by AFM nanolithography via local anodic oxidation (LAO) of dodecyl-terminated silicon and are negatively charged due to the production process. Therefore cationic spermine-functionalized perylene bisimide (sf-PBI) molecules can be bound to the structures by electrostatic interactions. The assembly of the sf-PBI units on the LAO nanostructures is verified by AFM height measurements and means of fluorescence microscopy. Emission spectra from the dye-functionalized oxide show that the molecules are able to form excimers. These excimers are characterized by a broad and featureless red-shifted emission band and an increased excited state life time. In contrast to the emission of sf-PBI films on uncharged silicon oxide, the excimer emission was found to decrease strongly low temperatures. This might be explained by a very tight binding due to the electrostatic attraction of the molecules to the LAO oxide.}, author = {Baumgärtel, T. and Rehm, S. and Würthner, F. and von Borczyskowski, C. and Graaf, H.}, journal = {Applied Surface Science}, keywords = {Diimide}, note = {NANOTR9, 9th Nanoscience and Nanotechnology Conference Special Issue}, number = {Supplement C}, pages = {51 - 58}, title = {Functional bisimide dyes bound via electrostatic interactions to oxide nanostructures generated by AFM lithography}, volume = 318, year = 2014 }

  %0 Journal Article %1 BAUMGARTEL201451 %A Baumgärtel, T. %A Rehm, S. %A Würthner, F. %A von Borczyskowski, C. %A Graaf, H. %D 2014 %J Applied Surface Science %N Supplement C %P 51 - 58 %R https://doi.org/10.1016/j.apsusc.2013.12.094 %T Functional bisimide dyes bound via electrostatic interactions to oxide nanostructures generated by AFM lithography %U http://www.sciencedirect.com/science/article/pii/S0169433213023830 %V 318 %X Abstract Silicon oxide nanostructures have been functionalized by selective binding of a positively charged bisimide dye derivative. The structures were prepared by AFM nanolithography via local anodic oxidation (LAO) of dodecyl-terminated silicon and are negatively charged due to the production process. Therefore cationic spermine-functionalized perylene bisimide (sf-PBI) molecules can be bound to the structures by electrostatic interactions. The assembly of the sf-PBI units on the LAO nanostructures is verified by AFM height measurements and means of fluorescence microscopy. Emission spectra from the dye-functionalized oxide show that the molecules are able to form excimers. These excimers are characterized by a broad and featureless red-shifted emission band and an increased excited state life time. In contrast to the emission of sf-PBI films on uncharged silicon oxide, the excimer emission was found to decrease strongly low temperatures. This might be explained by a very tight binding due to the electrostatic attraction of the molecules to the LAO oxide.
• Synthesis and Structural Analysis of Thiophene-Pyrrole-Based S,N-Heteroacenes. Wetzel, Christoph; Mishra, Amaresh; Mena-Osteritz, Elena; Liess, Andreas; Stolte, Matthias; Würthner, Frank; Bäuerle, Peter. In Organic Letters, 16(2), pp. 362–365. 2014.

  PMID: 24359234
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  Fused S,N-heterohexacene 4 was synthesized by applying Pd-catalyzed tandem Buchwald–Hartwig coupling and further functionalized to corresponding acceptor-capped derivatives 5 and 6 showing bond length equalization in the π-conjugated backbone and intense optical transitions. Organic thin film transistors (OTFTs) based on a vacuum-deposited film of 6 exhibit p-channel charge-carrier mobilities as high as 0.021 cm2 V–1 s–1 and current on/off ratios of 105.

  @article{doi:10.1021/ol403153z, abstract = {Fused S,N-heterohexacene 4 was synthesized by applying Pd-catalyzed tandem Buchwald–Hartwig coupling and further functionalized to corresponding acceptor-capped derivatives 5 and 6 showing bond length equalization in the π-conjugated backbone and intense optical transitions. Organic thin film transistors (OTFTs) based on a vacuum-deposited film of 6 exhibit p-channel charge-carrier mobilities as high as 0.021 cm2 V–1 s–1 and current on/off ratios of 105.}, author = {Wetzel, Christoph and Mishra, Amaresh and Mena-Osteritz, Elena and Liess, Andreas and Stolte, Matthias and Würthner, Frank and Bäuerle, Peter}, journal = {Organic Letters}, keywords = {myown}, note = {PMID: 24359234}, number = 2, pages = {362-365}, title = {Synthesis and Structural Analysis of Thiophene-Pyrrole-Based S,N-Heteroacenes}, volume = 16, year = 2014 }

  %0 Journal Article %1 doi:10.1021/ol403153z %A Wetzel, Christoph %A Mishra, Amaresh %A Mena-Osteritz, Elena %A Liess, Andreas %A Stolte, Matthias %A Würthner, Frank %A Bäuerle, Peter %D 2014 %J Organic Letters %N 2 %P 362-365 %R 10.1021/ol403153z %T Synthesis and Structural Analysis of Thiophene-Pyrrole-Based S,N-Heteroacenes %U http://dx.doi.org/10.1021/ol403153z %V 16 %X Fused S,N-heterohexacene 4 was synthesized by applying Pd-catalyzed tandem Buchwald–Hartwig coupling and further functionalized to corresponding acceptor-capped derivatives 5 and 6 showing bond length equalization in the π-conjugated backbone and intense optical transitions. Organic thin film transistors (OTFTs) based on a vacuum-deposited film of 6 exhibit p-channel charge-carrier mobilities as high as 0.021 cm2 V–1 s–1 and current on/off ratios of 105.
• Stepwise Decrease of Fluorescence versus Sequential Photobleaching in a Single Multichromophoric System. Issac, Abey; Hildner, Richard; Hippius, Catharina; Würthner, Frank; Köhler, Jürgen. In ACS Nano, 8(2), pp. 1708–1717. 2014.

  PMID: 24444041
  • [ Abstract ]
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  For individual molecules from the newly synthesized calix[4]arene tethered perylene bisimide (PBI) trimer, we studied the emitted fluorescence intensity as a function of time. Owing to the zigzag arrangement of PBI dyes in these trimers, the polarization state of the emission provides directly information about the emitting subunit within the trimer. Interestingly, we observed emission from all neutral subunits within a trimer rather than exclusively from the subunit with the lowest site energy. This can be understood in terms of thermally activated uphill energy transfer that repopulates the higher energetic chromophores. Together with the simultaneously recorded polarization-resolved emission spectra, this reveals that the emission from a multichromophoric system is governed by a complex interplay between the temporal variations of the photophysical parameters of the subunits, bidirectional hopping processes within the trimer, and unavoidable photobleaching. Moreover, it is demonstrated that the typically observed stepwise decrease of the signal from a multichromophoric system does not necessarily reflect sequential bleaching of the individual chromophores within the macromolecule.

  @article{doi:10.1021/nn4060946, abstract = {For individual molecules from the newly synthesized calix[4]arene tethered perylene bisimide (PBI) trimer, we studied the emitted fluorescence intensity as a function of time. Owing to the zigzag arrangement of PBI dyes in these trimers, the polarization state of the emission provides directly information about the emitting subunit within the trimer. Interestingly, we observed emission from all neutral subunits within a trimer rather than exclusively from the subunit with the lowest site energy. This can be understood in terms of thermally activated uphill energy transfer that repopulates the higher energetic chromophores. Together with the simultaneously recorded polarization-resolved emission spectra, this reveals that the emission from a multichromophoric system is governed by a complex interplay between the temporal variations of the photophysical parameters of the subunits, bidirectional hopping processes within the trimer, and unavoidable photobleaching. Moreover, it is demonstrated that the typically observed stepwise decrease of the signal from a multichromophoric system does not necessarily reflect sequential bleaching of the individual chromophores within the macromolecule.}, author = {Issac, Abey and Hildner, Richard and Hippius, Catharina and Würthner, Frank and Köhler, Jürgen}, journal = {ACS Nano}, keywords = {myown}, note = {PMID: 24444041}, number = 2, pages = {1708-1717}, title = {Stepwise Decrease of Fluorescence versus Sequential Photobleaching in a Single Multichromophoric System}, volume = 8, year = 2014 }

  %0 Journal Article %1 doi:10.1021/nn4060946 %A Issac, Abey %A Hildner, Richard %A Hippius, Catharina %A Würthner, Frank %A Köhler, Jürgen %D 2014 %J ACS Nano %N 2 %P 1708-1717 %R 10.1021/nn4060946 %T Stepwise Decrease of Fluorescence versus Sequential Photobleaching in a Single Multichromophoric System %U http://dx.doi.org/10.1021/nn4060946 %V 8 %X For individual molecules from the newly synthesized calix[4]arene tethered perylene bisimide (PBI) trimer, we studied the emitted fluorescence intensity as a function of time. Owing to the zigzag arrangement of PBI dyes in these trimers, the polarization state of the emission provides directly information about the emitting subunit within the trimer. Interestingly, we observed emission from all neutral subunits within a trimer rather than exclusively from the subunit with the lowest site energy. This can be understood in terms of thermally activated uphill energy transfer that repopulates the higher energetic chromophores. Together with the simultaneously recorded polarization-resolved emission spectra, this reveals that the emission from a multichromophoric system is governed by a complex interplay between the temporal variations of the photophysical parameters of the subunits, bidirectional hopping processes within the trimer, and unavoidable photobleaching. Moreover, it is demonstrated that the typically observed stepwise decrease of the signal from a multichromophoric system does not necessarily reflect sequential bleaching of the individual chromophores within the macromolecule.
• Structure-property relationships for 1,7-diphenoxy-perylene bisimides in solution and in the solid state. Jimenez, Angel J.; Lin, Mei-Jin; Burschka, Christian; Becker, Johannes; Settels, Volker; Engels, Bernd; Würthner, Frank. In Chem. Sci., 5(2), pp. 608–619. 2014.
  • [ Abstract ]
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  To elucidate the impact of widely employed solubilizing phenoxy substituents on the structural and functional properties of perylene bisimide (PBI) dyes a series of 1,7-diphenoxy-substituted PBIs was prepared from 1,7-dibromo PBI which exhibit hydrogen, methyl, isopropyl or phenyl substituents at one or both ortho positions of the phenoxy substituents. Despite increasing sterical congestion high yields of 74-88% could be obtained for all twofold aromatic nucleophilic substitution reactions. The structural and optical properties in solution and in the solid state were investigated by 1H NMR, UV-Vis absorption and fluorescence spectroscopy, single crystal X-ray analyses (four structures) as well as quantum chemical and force field calculations. For the latter we used an adapted force field which correctly reflects the rigidity of the PBI core. Our studies show that these dyes prefer to accommodate a slightly twisted molecular structure in solution that is supported by CHthree dots, centeredO hydrogen bonds between the 1,7-oxygen and the 6,12-hydrogen substituents. Because of the rather shallow potential energy surface, however, the molecules may planarize in the crystalline state under the influence of packing forces as revealed by single crystal X-ray analyses for two derivatives bearing methyl or phenyl substituents at all phenoxy ortho-positions. Such substituents are also suited to enwrap the PBI small pi-scaffold and to prohibit PBI aggregation in the bulk state giving rise to defined vibronic progressions in the solid state UV-Vis absorption and emission spectra, and appreciable fluorescence quantum yields of up to 37%. In dichloromethane solution all of these 1,7-diphenoxy-substituted PBI dyes exhibit fluorescence quantum yields of 98-100% despite significant differences in the shape of the UV-Vis absorption band. The latter was explained in terms of rigidity because the molecules bearing four ortho-substituents at the phenoxy substituents were shown to prevail in much more fixed conformations compared to their more simple counterparts. Our findings underline that the conformational flexibility of bay-substituents can have an important impact on the functional properties of PBI dyes.

  @article{C3SC52344F, abstract = {To elucidate the impact of widely employed solubilizing phenoxy substituents on the structural and functional properties of perylene bisimide (PBI) dyes a series of 1,7-diphenoxy-substituted PBIs was prepared from 1,7-dibromo PBI which exhibit hydrogen, methyl, isopropyl or phenyl substituents at one or both ortho positions of the phenoxy substituents. Despite increasing sterical congestion high yields of 74-88% could be obtained for all twofold aromatic nucleophilic substitution reactions. The structural and optical properties in solution and in the solid state were investigated by 1H NMR, UV-Vis absorption and fluorescence spectroscopy, single crystal X-ray analyses (four structures) as well as quantum chemical and force field calculations. For the latter we used an adapted force field which correctly reflects the rigidity of the PBI core. Our studies show that these dyes prefer to accommodate a slightly twisted molecular structure in solution that is supported by CHthree dots, centeredO hydrogen bonds between the 1,7-oxygen and the 6,12-hydrogen substituents. Because of the rather shallow potential energy surface, however, the molecules may planarize in the crystalline state under the influence of packing forces as revealed by single crystal X-ray analyses for two derivatives bearing methyl or phenyl substituents at all phenoxy ortho-positions. Such substituents are also suited to enwrap the PBI small pi-scaffold and to prohibit PBI aggregation in the bulk state giving rise to defined vibronic progressions in the solid state UV-Vis absorption and emission spectra, and appreciable fluorescence quantum yields of up to 37%. In dichloromethane solution all of these 1,7-diphenoxy-substituted PBI dyes exhibit fluorescence quantum yields of 98-100% despite significant differences in the shape of the UV-Vis absorption band. The latter was explained in terms of rigidity because the molecules bearing four ortho-substituents at the phenoxy substituents were shown to prevail in much more fixed conformations compared to their more simple counterparts. Our findings underline that the conformational flexibility of bay-substituents can have an important impact on the functional properties of PBI dyes.}, author = {Jimenez, Angel J. and Lin, Mei-Jin and Burschka, Christian and Becker, Johannes and Settels, Volker and Engels, Bernd and Würthner, Frank}, journal = {Chem. Sci.}, keywords = {myown}, number = 2, pages = {608-619}, publisher = {The Royal Society of Chemistry}, title = {Structure-property relationships for 1,7-diphenoxy-perylene bisimides in solution and in the solid state}, volume = 5, year = 2014 }

  %0 Journal Article %1 C3SC52344F %A Jimenez, Angel J. %A Lin, Mei-Jin %A Burschka, Christian %A Becker, Johannes %A Settels, Volker %A Engels, Bernd %A Würthner, Frank %D 2014 %I The Royal Society of Chemistry %J Chem. Sci. %N 2 %P 608-619 %R 10.1039/C3SC52344F %T Structure-property relationships for 1,7-diphenoxy-perylene bisimides in solution and in the solid state %U http://dx.doi.org/10.1039/C3SC52344F %V 5 %X To elucidate the impact of widely employed solubilizing phenoxy substituents on the structural and functional properties of perylene bisimide (PBI) dyes a series of 1,7-diphenoxy-substituted PBIs was prepared from 1,7-dibromo PBI which exhibit hydrogen, methyl, isopropyl or phenyl substituents at one or both ortho positions of the phenoxy substituents. Despite increasing sterical congestion high yields of 74-88% could be obtained for all twofold aromatic nucleophilic substitution reactions. The structural and optical properties in solution and in the solid state were investigated by 1H NMR, UV-Vis absorption and fluorescence spectroscopy, single crystal X-ray analyses (four structures) as well as quantum chemical and force field calculations. For the latter we used an adapted force field which correctly reflects the rigidity of the PBI core. Our studies show that these dyes prefer to accommodate a slightly twisted molecular structure in solution that is supported by CHthree dots, centeredO hydrogen bonds between the 1,7-oxygen and the 6,12-hydrogen substituents. Because of the rather shallow potential energy surface, however, the molecules may planarize in the crystalline state under the influence of packing forces as revealed by single crystal X-ray analyses for two derivatives bearing methyl or phenyl substituents at all phenoxy ortho-positions. Such substituents are also suited to enwrap the PBI small pi-scaffold and to prohibit PBI aggregation in the bulk state giving rise to defined vibronic progressions in the solid state UV-Vis absorption and emission spectra, and appreciable fluorescence quantum yields of up to 37%. In dichloromethane solution all of these 1,7-diphenoxy-substituted PBI dyes exhibit fluorescence quantum yields of 98-100% despite significant differences in the shape of the UV-Vis absorption band. The latter was explained in terms of rigidity because the molecules bearing four ortho-substituents at the phenoxy substituents were shown to prevail in much more fixed conformations compared to their more simple counterparts. Our findings underline that the conformational flexibility of bay-substituents can have an important impact on the functional properties of PBI dyes.
• Comparative Studies on Optical, Redox, and Photovoltaic Properties of a Series of D–A–D and Analogous D–A Chromophores. Zitzler-Kunkel, André; Lenze, Martin R.; Schnier, Tobias; Meerholz, Klaus; Würthner, Frank. In Advanced Functional Materials, 24(29), pp. 4645–4653. 2014.
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  A series of new symmetrical donor-acceptor-donor (D−A−D) dyes based on s-indacene-1,3,5,7(2H,6H)-tetraone as an acceptor unit containing varying electron donating moieties and analogous donor-acceptor (D−A) chromophores with indane-1,3-dione as an acceptor are synthesized. By employing these two sets of dyes, the influence of a scaffold change from unsymmetric push-pull (D−A) to symmetrical (D−A−D) systems on optical, electrochemical, and photovoltaic properties are explored. Detailed comparative studies reveal favorable optical characteristics and considerably decreased bandgaps for the D−A−D dyes compared to those of the reference D−A chromophores. Accordingly, the evaluation of the present dyes as donor materials in bulk heterojunction (BHJ) solar cells in combination with fullerene derivatives PC61BM or PC71BM as acceptors afforded significantly improved performance for devices based on D−A−D blends (up to a factor of 4 compared to the respective D-A reference) with power conversion efficiencies of up to 2.8%. In less polar solvents such as toluene, some of the novel D−A−D chromophores exhibit unexpectedly high fluorescence quantum yields Φem of up to unity, in striking contrast to their weakly fluorescent D-A counterparts.

  @article{ADFM:ADFM201400455, abstract = {A series of new symmetrical donor-acceptor-donor (D−A−D) dyes based on s-indacene-1,3,5,7(2H,6H)-tetraone as an acceptor unit containing varying electron donating moieties and analogous donor-acceptor (D−A) chromophores with indane-1,3-dione as an acceptor are synthesized. By employing these two sets of dyes, the influence of a scaffold change from unsymmetric push-pull (D−A) to symmetrical (D−A−D) systems on optical, electrochemical, and photovoltaic properties are explored. Detailed comparative studies reveal favorable optical characteristics and considerably decreased bandgaps for the D−A−D dyes compared to those of the reference D−A chromophores. Accordingly, the evaluation of the present dyes as donor materials in bulk heterojunction (BHJ) solar cells in combination with fullerene derivatives PC61BM or PC71BM as acceptors afforded significantly improved performance for devices based on D−A−D blends (up to a factor of 4 compared to the respective D-A reference) with power conversion efficiencies of up to 2.8%. In less polar solvents such as toluene, some of the novel D−A−D chromophores exhibit unexpectedly high fluorescence quantum yields Φem of up to unity, in striking contrast to their weakly fluorescent D-A counterparts.}, author = {Zitzler-Kunkel, André and Lenze, Martin R. and Schnier, Tobias and Meerholz, Klaus and Würthner, Frank}, journal = {Advanced Functional Materials}, keywords = {myown}, number = 29, pages = {4645–4653}, title = {Comparative Studies on Optical, Redox, and Photovoltaic Properties of a Series of D–A–D and Analogous D–A Chromophores}, volume = 24, year = 2014 }

  %0 Journal Article %1 ADFM:ADFM201400455 %A Zitzler-Kunkel, André %A Lenze, Martin R. %A Schnier, Tobias %A Meerholz, Klaus %A Würthner, Frank %D 2014 %J Advanced Functional Materials %N 29 %P 4645--4653 %R 10.1002/adfm.201400455 %T Comparative Studies on Optical, Redox, and Photovoltaic Properties of a Series of D–A–D and Analogous D–A Chromophores %U http://dx.doi.org/10.1002/adfm.201400455 %V 24 %X A series of new symmetrical donor-acceptor-donor (D−A−D) dyes based on s-indacene-1,3,5,7(2H,6H)-tetraone as an acceptor unit containing varying electron donating moieties and analogous donor-acceptor (D−A) chromophores with indane-1,3-dione as an acceptor are synthesized. By employing these two sets of dyes, the influence of a scaffold change from unsymmetric push-pull (D−A) to symmetrical (D−A−D) systems on optical, electrochemical, and photovoltaic properties are explored. Detailed comparative studies reveal favorable optical characteristics and considerably decreased bandgaps for the D−A−D dyes compared to those of the reference D−A chromophores. Accordingly, the evaluation of the present dyes as donor materials in bulk heterojunction (BHJ) solar cells in combination with fullerene derivatives PC61BM or PC71BM as acceptors afforded significantly improved performance for devices based on D−A−D blends (up to a factor of 4 compared to the respective D-A reference) with power conversion efficiencies of up to 2.8%. In less polar solvents such as toluene, some of the novel D−A−D chromophores exhibit unexpectedly high fluorescence quantum yields Φem of up to unity, in striking contrast to their weakly fluorescent D-A counterparts.
• Cyanated isoindigos for n-type and ambipolar organic thin film transistors. Yue, Wan; He, Tao; Stolte, Matthias; Gsanger, Marcel; Würthner, Frank. In Chem. Commun., 50(5), pp. 545–547. 2014.
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  A set of three core-cyanated isoindigos was synthesized by palladium-catalyzed cyanation of core-brominated isoindigos. With decreased LUMO level to -3.88 eV, the dicyanated isoindigo 5 showed ambient-stable electron mobility up to 0.044 cm2 V-1 s-1 in OTFTs with SAMs of TPA, while it exhibited ambipolar charge transport behaviour (0.11 cm2 V-1 s-1 for electrons and 0.045 cm2 V-1 s-1 for holes) on FOPA-modified substrates.

  @article{C3CC48037B, abstract = {A set of three core-cyanated isoindigos was synthesized by palladium-catalyzed cyanation of core-brominated isoindigos. With decreased LUMO level to -3.88 eV{,} the dicyanated isoindigo 5 showed ambient-stable electron mobility up to 0.044 cm2 V-1 s-1 in OTFTs with SAMs of TPA{,} while it exhibited ambipolar charge transport behaviour (0.11 cm2 V-1 s-1 for electrons and 0.045 cm2 V-1 s-1 for holes) on FOPA-modified substrates.}, author = {Yue, Wan and He, Tao and Stolte, Matthias and Gsanger, Marcel and Würthner, Frank}, journal = {Chem. Commun.}, keywords = {myown}, number = 5, pages = {545-547}, publisher = {The Royal Society of Chemistry}, title = {Cyanated isoindigos for n-type and ambipolar organic thin film transistors}, volume = 50, year = 2014 }

  %0 Journal Article %1 C3CC48037B %A Yue, Wan %A He, Tao %A Stolte, Matthias %A Gsanger, Marcel %A Würthner, Frank %D 2014 %I The Royal Society of Chemistry %J Chem. Commun. %N 5 %P 545-547 %R 10.1039/C3CC48037B %T Cyanated isoindigos for n-type and ambipolar organic thin film transistors %U http://dx.doi.org/10.1039/C3CC48037B %V 50 %X A set of three core-cyanated isoindigos was synthesized by palladium-catalyzed cyanation of core-brominated isoindigos. With decreased LUMO level to -3.88 eV, the dicyanated isoindigo 5 showed ambient-stable electron mobility up to 0.044 cm2 V-1 s-1 in OTFTs with SAMs of TPA, while it exhibited ambipolar charge transport behaviour (0.11 cm2 V-1 s-1 for electrons and 0.045 cm2 V-1 s-1 for holes) on FOPA-modified substrates.
• A multi-property fluorescent probe for the investigation of polymer dynamics near the glass transition. Siekierzycka, Joanna R.; Hippius, Catharina; Würthner, Frank; Williams, René M.; Brouwer, Albert M. In Central European Journal of Chemistry, 12(9), pp. 937–952. 2014.
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  In addition to the commonly observed single molecule fluorescence intensity fluctuations due to molecular reorientation dynamics, a perylene bisimide-calixarene compound (1) shows additional on-off fluctuations due to its ability to undergo intramolecular excited state electron transfer (PET). This quenching process is turned on rather sharply when a film of poly(vinylacetate) containing 1 is heated above its glass transition temperature (T g), which indicates that the electron transfer process depends on the availability of sufficient free volume. Spatial heterogeneities cause different individual molecules to reach the electron transfer regime at different temperatures, but these heterogeneities also fluctuate in time: in the matrix above T g molecules that are mostly nonfluorescent due to PET can become fluorescent again on timescales of seconds to minutes.

  @article{Siekierzycka2014, abstract = {In addition to the commonly observed single molecule fluorescence intensity fluctuations due to molecular reorientation dynamics, a perylene bisimide-calixarene compound (1) shows additional on-off fluctuations due to its ability to undergo intramolecular excited state electron transfer (PET). This quenching process is turned on rather sharply when a film of poly(vinylacetate) containing 1 is heated above its glass transition temperature (T g), which indicates that the electron transfer process depends on the availability of sufficient free volume. Spatial heterogeneities cause different individual molecules to reach the electron transfer regime at different temperatures, but these heterogeneities also fluctuate in time: in the matrix above T g molecules that are mostly nonfluorescent due to PET can become fluorescent again on timescales of seconds to minutes.}, author = {Siekierzycka, Joanna R. and Hippius, Catharina and Würthner, Frank and Williams, René M. and Brouwer, Albert M.}, journal = {Central European Journal of Chemistry}, keywords = {myown}, month = {09}, number = 9, pages = {937–952}, title = {A multi-property fluorescent probe for the investigation of polymer dynamics near the glass transition}, volume = 12, year = 2014 }

  %0 Journal Article %1 Siekierzycka2014 %A Siekierzycka, Joanna R. %A Hippius, Catharina %A Würthner, Frank %A Williams, René M. %A Brouwer, Albert M. %D 2014 %J Central European Journal of Chemistry %N 9 %P 937--952 %R 10.2478/s11532-014-0544-0 %T A multi-property fluorescent probe for the investigation of polymer dynamics near the glass transition %U https://doi.org/10.2478/s11532-014-0544-0 %V 12 %X In addition to the commonly observed single molecule fluorescence intensity fluctuations due to molecular reorientation dynamics, a perylene bisimide-calixarene compound (1) shows additional on-off fluctuations due to its ability to undergo intramolecular excited state electron transfer (PET). This quenching process is turned on rather sharply when a film of poly(vinylacetate) containing 1 is heated above its glass transition temperature (T g), which indicates that the electron transfer process depends on the availability of sufficient free volume. Spatial heterogeneities cause different individual molecules to reach the electron transfer regime at different temperatures, but these heterogeneities also fluctuate in time: in the matrix above T g molecules that are mostly nonfluorescent due to PET can become fluorescent again on timescales of seconds to minutes.
• Strategies for the Synthesis of Functional Naphthalene Diimides. Suraru, Sabin-Lucian; Würthner, Frank. In Angew. Chem. Int. Ed., 53(29), pp. 7428–7448. 2014.
  • [ Abstract ]
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  Naphthalene diimides, which have for a long time been in the shadow of their higher homologues the perylene diimides, currently belong to the most investigated classes of organic compounds. This is primarily due to the initial synthetic studies on core functionalization that were carried out at the beginning of the last decade, which facilitated diverse structural modifications of the naphthalene scaffold. Compounds with greatly modified optical and electronic properties that can be easily and effectively modulated by appropriate functionalization were made accessible through relatively little synthetic effort. This resulted in diverse interesting applications. The electron-deficient character of these compounds makes them highly valuable, particularly in the field of organic electronics as air-stable n-type semiconductors, while absorption bands over the whole visible spectral range through the introduction of core substituents enabled interesting photosystems and photovoltaic applications. This Review provides an overview on different approaches towards core functionalization as well as on synthetic strategies for the core expansion of naphthalene diimides that have been developed mainly in the last five years.

  @article{ANIE:ANIE201309746, abstract = {Naphthalene diimides, which have for a long time been in the shadow of their higher homologues the perylene diimides, currently belong to the most investigated classes of organic compounds. This is primarily due to the initial synthetic studies on core functionalization that were carried out at the beginning of the last decade, which facilitated diverse structural modifications of the naphthalene scaffold. Compounds with greatly modified optical and electronic properties that can be easily and effectively modulated by appropriate functionalization were made accessible through relatively little synthetic effort. This resulted in diverse interesting applications. The electron-deficient character of these compounds makes them highly valuable, particularly in the field of organic electronics as air-stable n-type semiconductors, while absorption bands over the whole visible spectral range through the introduction of core substituents enabled interesting photosystems and photovoltaic applications. This Review provides an overview on different approaches towards core functionalization as well as on synthetic strategies for the core expansion of naphthalene diimides that have been developed mainly in the last five years.}, author = {Suraru, Sabin-Lucian and Würthner, Frank}, journal = {Angew. Chem. Int. Ed.}, keywords = {myown}, number = 29, pages = {7428–7448}, publisher = {WILEY-VCH Verlag}, title = {Strategies for the Synthesis of Functional Naphthalene Diimides}, volume = 53, year = 2014 }

  %0 Journal Article %1 ANIE:ANIE201309746 %A Suraru, Sabin-Lucian %A Würthner, Frank %D 2014 %I WILEY-VCH Verlag %J Angew. Chem. Int. Ed. %N 29 %P 7428--7448 %R 10.1002/anie.201309746 %T Strategies for the Synthesis of Functional Naphthalene Diimides %U http://dx.doi.org/10.1002/anie.201309746 %V 53 %X Naphthalene diimides, which have for a long time been in the shadow of their higher homologues the perylene diimides, currently belong to the most investigated classes of organic compounds. This is primarily due to the initial synthetic studies on core functionalization that were carried out at the beginning of the last decade, which facilitated diverse structural modifications of the naphthalene scaffold. Compounds with greatly modified optical and electronic properties that can be easily and effectively modulated by appropriate functionalization were made accessible through relatively little synthetic effort. This resulted in diverse interesting applications. The electron-deficient character of these compounds makes them highly valuable, particularly in the field of organic electronics as air-stable n-type semiconductors, while absorption bands over the whole visible spectral range through the introduction of core substituents enabled interesting photosystems and photovoltaic applications. This Review provides an overview on different approaches towards core functionalization as well as on synthetic strategies for the core expansion of naphthalene diimides that have been developed mainly in the last five years.
• Diindole-Annulated Naphthalene Diimides: Synthesis and Optical and Electronic Properties of Syn- and Anti-Isomers. Suraru, Sabin-Lucian; Burschka, Christian; Würthner, Frank. In The Journal of Organic Chemistry, 79(1), pp. 128–139. 2014.
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  Here we report a selective method for the core-extension of naphthalene diimide (NDI) with two annulated indole rings leading to carbazolo[2,3-b]carbazole diimides (CbDIs) with exclusive syn-connectivity based on a regioselective nucleophilic substitution reaction of Br4-NDI with arylamines, followed by palladium-catalyzed intramolecular C–C coupling. The oxygen analogues of anti-CbDIs, namely anti-benzofurobenzofuran diimides (anti-BfDIs), were obtained from 2,6-Br2-NDI and 2-bromophenol. The syn- and anti-isomers of CbDIs were unambiguously characterized by single-crystal X-ray analysis. The optical properties of the present core-enlarged NDIs were studied, revealing clear differences in the absorption characteristics of the syn- and anti-isomers of CbDI, on one hand, and CbDI vs BfDI derivatives, on the other hand. Cyclic voltammetry studies showed that the redox properties are dependent on the substituents at the CbDI-core and oxygen atom containing BfDIs are more prone to reduction than the respective nitrogen analogues CbDIs. Vacuum-processed organic field effect transistors reveal CbDI and BfDI derivatives with n-channel, p-channel, as well as ambient transport characteristics with mobility values up to 0.2 cm2/(V s).

  @article{doi:10.1021/jo402365s, abstract = {Here we report a selective method for the core-extension of naphthalene diimide (NDI) with two annulated indole rings leading to carbazolo[2,3-b]carbazole diimides (CbDIs) with exclusive syn-connectivity based on a regioselective nucleophilic substitution reaction of Br4-NDI with arylamines, followed by palladium-catalyzed intramolecular C–C coupling. The oxygen analogues of anti-CbDIs, namely anti-benzofurobenzofuran diimides (anti-BfDIs), were obtained from 2,6-Br2-NDI and 2-bromophenol. The syn- and anti-isomers of CbDIs were unambiguously characterized by single-crystal X-ray analysis. The optical properties of the present core-enlarged NDIs were studied, revealing clear differences in the absorption characteristics of the syn- and anti-isomers of CbDI, on one hand, and CbDI vs BfDI derivatives, on the other hand. Cyclic voltammetry studies showed that the redox properties are dependent on the substituents at the CbDI-core and oxygen atom containing BfDIs are more prone to reduction than the respective nitrogen analogues CbDIs. Vacuum-processed organic field effect transistors reveal CbDI and BfDI derivatives with n-channel, p-channel, as well as ambient transport characteristics with mobility values up to 0.2 cm2/(V s).}, author = {Suraru, Sabin-Lucian and Burschka, Christian and Würthner, Frank}, journal = {The Journal of Organic Chemistry}, keywords = {myown}, number = 1, pages = {128-139}, title = {Diindole-Annulated Naphthalene Diimides: Synthesis and Optical and Electronic Properties of Syn- and Anti-Isomers}, volume = 79, year = 2014 }

  %0 Journal Article %1 doi:10.1021/jo402365s %A Suraru, Sabin-Lucian %A Burschka, Christian %A Würthner, Frank %D 2014 %J The Journal of Organic Chemistry %N 1 %P 128-139 %R 10.1021/jo402365s %T Diindole-Annulated Naphthalene Diimides: Synthesis and Optical and Electronic Properties of Syn- and Anti-Isomers %U http://dx.doi.org/10.1021/jo402365s %V 79 %X Here we report a selective method for the core-extension of naphthalene diimide (NDI) with two annulated indole rings leading to carbazolo[2,3-b]carbazole diimides (CbDIs) with exclusive syn-connectivity based on a regioselective nucleophilic substitution reaction of Br4-NDI with arylamines, followed by palladium-catalyzed intramolecular C–C coupling. The oxygen analogues of anti-CbDIs, namely anti-benzofurobenzofuran diimides (anti-BfDIs), were obtained from 2,6-Br2-NDI and 2-bromophenol. The syn- and anti-isomers of CbDIs were unambiguously characterized by single-crystal X-ray analysis. The optical properties of the present core-enlarged NDIs were studied, revealing clear differences in the absorption characteristics of the syn- and anti-isomers of CbDI, on one hand, and CbDI vs BfDI derivatives, on the other hand. Cyclic voltammetry studies showed that the redox properties are dependent on the substituents at the CbDI-core and oxygen atom containing BfDIs are more prone to reduction than the respective nitrogen analogues CbDIs. Vacuum-processed organic field effect transistors reveal CbDI and BfDI derivatives with n-channel, p-channel, as well as ambient transport characteristics with mobility values up to 0.2 cm2/(V s).
• Supramolecular adducts of squaraine and protein for noninvasive tumor imaging and photothermal therapy in vivo. Gao, Fu-Ping; Lin, Yao-Xin; Li, Li-Li; Liu, Ya; Mayerhöffer, Ulrich; Spenst, Peter; Su, Ji-Guo; Li, Jing-Yuan; Würthner, Frank; Wang, Hao. In Biomaterials, 35(3), pp. 1004–1014. 2014.
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  Abstract Extensive efforts have been devoted to the development of near-infrared (NIR) dye-based imaging probes and/or photothermal agents for cancer theranostics in vivo. However, the intrinsic chemical instability and self-aggregation properties of NIR dyes in physiological condition limit their widely applications in the pre-clinic study in living animals. Squaraine dyes are among the most promising NIR fluorophores with high absorption coefficiencies, bright fluorescence and photostability. By introducing dicyanovinyl groups into conventional squaraine (SQ) skeleton. These acceptor-substituted SQ dyes not only show superior NIR fluorescence properties (longer wavelength, higher quantum yield) but also exhibit more chemical robustness. In this work, we demonstrated highly stable and biocompatible supramolecular adducts of SQ and the natural carrier protein, i.e., bovine serum albumin (BSA) (SQ⊂BSA) for tumor targeted imaging and photothermal therapy in vivo. SQ was selectively bound to BSA hydrophobic domain via hydrophobic and hydrogen bonding interactions with up to 80-fold enhanced fluorescence intensity. By covalently conjugating target ligands to BSA, the SQ⊂BSA was capable of targeting tumor sites and allowed for monitoring the time-dependent biodistribution of SQ⊂BSA, which consequently determined the protocol of photothermal therapy in vivo. We envision that this supramolecular strategy for selectively binding functional imaging agents and/or drugs into human serum albumin might potentially utilize in the preclinical and even clinic studies in the future.

  @article{GAO20141004, abstract = {Abstract Extensive efforts have been devoted to the development of near-infrared (NIR) dye-based imaging probes and/or photothermal agents for cancer theranostics in vivo. However, the intrinsic chemical instability and self-aggregation properties of NIR dyes in physiological condition limit their widely applications in the pre-clinic study in living animals. Squaraine dyes are among the most promising NIR fluorophores with high absorption coefficiencies, bright fluorescence and photostability. By introducing dicyanovinyl groups into conventional squaraine (SQ) skeleton. These acceptor-substituted SQ dyes not only show superior NIR fluorescence properties (longer wavelength, higher quantum yield) but also exhibit more chemical robustness. In this work, we demonstrated highly stable and biocompatible supramolecular adducts of SQ and the natural carrier protein, i.e., bovine serum albumin (BSA) (SQ⊂BSA) for tumor targeted imaging and photothermal therapy in vivo. SQ was selectively bound to BSA hydrophobic domain via hydrophobic and hydrogen bonding interactions with up to 80-fold enhanced fluorescence intensity. By covalently conjugating target ligands to BSA, the SQ⊂BSA was capable of targeting tumor sites and allowed for monitoring the time-dependent biodistribution of SQ⊂BSA, which consequently determined the protocol of photothermal therapy in vivo. We envision that this supramolecular strategy for selectively binding functional imaging agents and/or drugs into human serum albumin might potentially utilize in the preclinical and even clinic studies in the future.}, author = {Gao, Fu-Ping and Lin, Yao-Xin and Li, Li-Li and Liu, Ya and Mayerhöffer, Ulrich and Spenst, Peter and Su, Ji-Guo and Li, Jing-Yuan and Würthner, Frank and Wang, Hao}, journal = {Biomaterials}, keywords = {Photothermal}, number = 3, pages = {1004 - 1014}, title = {Supramolecular adducts of squaraine and protein for noninvasive tumor imaging and photothermal therapy in vivo}, volume = 35, year = 2014 }

  %0 Journal Article %1 GAO20141004 %A Gao, Fu-Ping %A Lin, Yao-Xin %A Li, Li-Li %A Liu, Ya %A Mayerhöffer, Ulrich %A Spenst, Peter %A Su, Ji-Guo %A Li, Jing-Yuan %A Würthner, Frank %A Wang, Hao %D 2014 %J Biomaterials %N 3 %P 1004 - 1014 %R https://doi.org/10.1016/j.biomaterials.2013.10.039 %T Supramolecular adducts of squaraine and protein for noninvasive tumor imaging and photothermal therapy in vivo %U http://www.sciencedirect.com/science/article/pii/S0142961213012696 %V 35 %X Abstract Extensive efforts have been devoted to the development of near-infrared (NIR) dye-based imaging probes and/or photothermal agents for cancer theranostics in vivo. However, the intrinsic chemical instability and self-aggregation properties of NIR dyes in physiological condition limit their widely applications in the pre-clinic study in living animals. Squaraine dyes are among the most promising NIR fluorophores with high absorption coefficiencies, bright fluorescence and photostability. By introducing dicyanovinyl groups into conventional squaraine (SQ) skeleton. These acceptor-substituted SQ dyes not only show superior NIR fluorescence properties (longer wavelength, higher quantum yield) but also exhibit more chemical robustness. In this work, we demonstrated highly stable and biocompatible supramolecular adducts of SQ and the natural carrier protein, i.e., bovine serum albumin (BSA) (SQ⊂BSA) for tumor targeted imaging and photothermal therapy in vivo. SQ was selectively bound to BSA hydrophobic domain via hydrophobic and hydrogen bonding interactions with up to 80-fold enhanced fluorescence intensity. By covalently conjugating target ligands to BSA, the SQ⊂BSA was capable of targeting tumor sites and allowed for monitoring the time-dependent biodistribution of SQ⊂BSA, which consequently determined the protocol of photothermal therapy in vivo. We envision that this supramolecular strategy for selectively binding functional imaging agents and/or drugs into human serum albumin might potentially utilize in the preclinical and even clinic studies in the future.

• An efficient merocyanine/zinc phthalocyanine tandem solar cell. Steinmann, V.; Umbach, T.E.; Schädel, M.; Krumrain, J.; Lenze, M.R.; Bürckstümmer, H.; Würthner, F.; Meerholz, K. In Organic Electronics, 14(8), pp. 2029–2033. 2013.
  • [ Abstract ]
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  Abstract We present a merocyanine:C60/zinc phthalocyanine:C60 tandem solar cell, comprising two complementary absorbing bulk heterojunction subcells connected in series. High-efficiency devices were realized in a rather simple tandem setup, consisting of only three organic layers that were successively deposited in an ultrahigh-vacuum chamber. The optimized tandem solar cell features an efficiency of 4.5%, demonstrating a performance improvement by ca. 50% compared to the individual optimized single-junction solar cells. The experimental data are in excellent agreement with optical simulations, assuming an internal quantum efficiency near unity in the optimized tandem device.

  @article{STEINMANN20132029, abstract = {Abstract We present a merocyanine:C60/zinc phthalocyanine:C60 tandem solar cell, comprising two complementary absorbing bulk heterojunction subcells connected in series. High-efficiency devices were realized in a rather simple tandem setup, consisting of only three organic layers that were successively deposited in an ultrahigh-vacuum chamber. The optimized tandem solar cell features an efficiency of 4.5%, demonstrating a performance improvement by ca. 50% compared to the individual optimized single-junction solar cells. The experimental data are in excellent agreement with optical simulations, assuming an internal quantum efficiency near unity in the optimized tandem device.}, author = {Steinmann, V. and Umbach, T.E. and Schädel, M. and Krumrain, J. and Lenze, M.R. and Bürckstümmer, H. and Würthner, F. and Meerholz, K.}, journal = {Organic Electronics}, keywords = {Merocyanines}, number = 8, pages = {2029 - 2033}, title = {An efficient merocyanine/zinc phthalocyanine tandem solar cell}, volume = 14, year = 2013 }

  %0 Journal Article %1 STEINMANN20132029 %A Steinmann, V. %A Umbach, T.E. %A Schädel, M. %A Krumrain, J. %A Lenze, M.R. %A Bürckstümmer, H. %A Würthner, F. %A Meerholz, K. %D 2013 %J Organic Electronics %N 8 %P 2029 - 2033 %R https://doi.org/10.1016/j.orgel.2013.03.032 %T An efficient merocyanine/zinc phthalocyanine tandem solar cell %U http://www.sciencedirect.com/science/article/pii/S1566119913001468 %V 14 %X Abstract We present a merocyanine:C60/zinc phthalocyanine:C60 tandem solar cell, comprising two complementary absorbing bulk heterojunction subcells connected in series. High-efficiency devices were realized in a rather simple tandem setup, consisting of only three organic layers that were successively deposited in an ultrahigh-vacuum chamber. The optimized tandem solar cell features an efficiency of 4.5%, demonstrating a performance improvement by ca. 50% compared to the individual optimized single-junction solar cells. The experimental data are in excellent agreement with optical simulations, assuming an internal quantum efficiency near unity in the optimized tandem device.
• Transition metal complexes of axially chiral tetrathioether bay-substituted perylene bisimide dyes. Lin, Mei-Jin; Schulze, Marcus; Radacki, Krzysztof; Würthner, Frank. In Chem. Commun., 49(80), pp. 9107–9109. 2013.
  • [ Abstract ]
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  Nucleophilic substitution of 1,6,7,12-tetrachloro perylene bisimide (PBI) with n-butanethiol provided a novel, highly twisted PBI bearing four sulphur coordination sites at the bay positions, from which silver and palladium complexes were prepared.

  @article{C3CC45351K, abstract = {Nucleophilic substitution of 1{,}6{,}7{,}12-tetrachloro perylene bisimide (PBI) with n-butanethiol provided a novel{,} highly twisted PBI bearing four sulphur coordination sites at the bay positions{,} from which silver and palladium complexes were prepared.}, author = {Lin, Mei-Jin and Schulze, Marcus and Radacki, Krzysztof and Würthner, Frank}, journal = {Chem. Commun.}, keywords = {myown}, number = 80, pages = {9107-9109}, publisher = {The Royal Society of Chemistry}, title = {Transition metal complexes of axially chiral tetrathioether bay-substituted perylene bisimide dyes}, volume = 49, year = 2013 }

  %0 Journal Article %1 C3CC45351K %A Lin, Mei-Jin %A Schulze, Marcus %A Radacki, Krzysztof %A Würthner, Frank %D 2013 %I The Royal Society of Chemistry %J Chem. Commun. %N 80 %P 9107-9109 %R 10.1039/C3CC45351K %T Transition metal complexes of axially chiral tetrathioether bay-substituted perylene bisimide dyes %U http://dx.doi.org/10.1039/C3CC45351K %V 49 %X Nucleophilic substitution of 1,6,7,12-tetrachloro perylene bisimide (PBI) with n-butanethiol provided a novel, highly twisted PBI bearing four sulphur coordination sites at the bay positions, from which silver and palladium complexes were prepared.
• Giant Electroactive M4L6 Tetrahedral Host Self-Assembled with Fe(II) Vertices and Perylene Bisimide Dye Edges. Mahata, Kingsuk; Frischmann, Peter D.; Würthner, Frank. In J. Am. Chem. Soc., 135(41), pp. 15656–15661. 2013.

  PMID: 24059438
  • [ Abstract ]
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  Self-assembly of octahedral Fe(II) ions and linear perylene bisimide (PBI) dyes with 2,2′-bipyridine groups covalently attached at the imide positions quantitatively yields an Fe4(PBI)6 tetrahedron by the directional bonding approach. With an edge length of 3.9 nm and estimated internal volume >950 Å3, tetrahedron T is one of the largest M4L6 tetrahedra ever reported. Importantly, many of the desirable photo- and electroactive properties of the PBI ligands are transferred to the nanoscale metallosupramolecule. Tetrahedron T absorbs strongly across the visible spectrum out to 650 nm and exhibits a total of 7 highly reversible electrochemical oxidation and reduction waves spanning a 3.0 V range. This facile cycling of 34 electrons between +18 and −16 charged species is likely enabled due to the porous nature of the tetrahedron that allows the necessary counterions to freely flow in and out of the host. Host–guest encapsulation of C60 by T in acetonitrile was studied by 13C NMR spectroscopy, UV–vis spectroscopy, and ESI-MS, confirming that the tetrahedron is a suitable host for large, functional guest molecules.

  @article{doi:10.1021/ja4083039, abstract = {Self-assembly of octahedral Fe(II) ions and linear perylene bisimide (PBI) dyes with 2,2′-bipyridine groups covalently attached at the imide positions quantitatively yields an Fe4(PBI)6 tetrahedron by the directional bonding approach. With an edge length of 3.9 nm and estimated internal volume >950 Å3, tetrahedron T is one of the largest M4L6 tetrahedra ever reported. Importantly, many of the desirable photo- and electroactive properties of the PBI ligands are transferred to the nanoscale metallosupramolecule. Tetrahedron T absorbs strongly across the visible spectrum out to 650 nm and exhibits a total of 7 highly reversible electrochemical oxidation and reduction waves spanning a 3.0 V range. This facile cycling of 34 electrons between +18 and −16 charged species is likely enabled due to the porous nature of the tetrahedron that allows the necessary counterions to freely flow in and out of the host. Host–guest encapsulation of C60 by T in acetonitrile was studied by 13C NMR spectroscopy, UV–vis spectroscopy, and ESI-MS, confirming that the tetrahedron is a suitable host for large, functional guest molecules.}, author = {Mahata, Kingsuk and Frischmann, Peter D. and Würthner, Frank}, journal = {J. Am. Chem. Soc.}, keywords = {myown}, note = {PMID: 24059438}, number = 41, pages = {15656-15661}, title = {Giant Electroactive M4L6 Tetrahedral Host Self-Assembled with Fe(II) Vertices and Perylene Bisimide Dye Edges}, volume = 135, year = 2013 }

  %0 Journal Article %1 doi:10.1021/ja4083039 %A Mahata, Kingsuk %A Frischmann, Peter D. %A Würthner, Frank %D 2013 %J J. Am. Chem. Soc. %N 41 %P 15656-15661 %R 10.1021/ja4083039 %T Giant Electroactive M4L6 Tetrahedral Host Self-Assembled with Fe(II) Vertices and Perylene Bisimide Dye Edges %U http://dx.doi.org/10.1021/ja4083039 %V 135 %X Self-assembly of octahedral Fe(II) ions and linear perylene bisimide (PBI) dyes with 2,2′-bipyridine groups covalently attached at the imide positions quantitatively yields an Fe4(PBI)6 tetrahedron by the directional bonding approach. With an edge length of 3.9 nm and estimated internal volume >950 Å3, tetrahedron T is one of the largest M4L6 tetrahedra ever reported. Importantly, many of the desirable photo- and electroactive properties of the PBI ligands are transferred to the nanoscale metallosupramolecule. Tetrahedron T absorbs strongly across the visible spectrum out to 650 nm and exhibits a total of 7 highly reversible electrochemical oxidation and reduction waves spanning a 3.0 V range. This facile cycling of 34 electrons between +18 and −16 charged species is likely enabled due to the porous nature of the tetrahedron that allows the necessary counterions to freely flow in and out of the host. Host–guest encapsulation of C60 by T in acetonitrile was studied by 13C NMR spectroscopy, UV–vis spectroscopy, and ESI-MS, confirming that the tetrahedron is a suitable host for large, functional guest molecules.
• Powering the future of molecular artificial photosynthesis with light-harvesting metallosupramolecular dye assemblies. Frischmann, Peter D.; Mahata, Kingsuk; Würthner, Frank. In Chem. Soc. Rev., 42(4), pp. 1847–1870. 2013.
  • [ Abstract ]
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  Chemical ingenuity will play a significant role in solving the greatest challenge currently facing society: providing clean and carbon neutral energy for all of humanity. Molecular artificial photosynthesis is an emerging technology based on principles learned from Nature where individual components perform the essential light-harvesting, charge-separation, and water splitting functions to store solar energy in the form of chemical bonds. This tutorial review focuses specifically on the application of metallosupramolecular self-assembly strategies to interface solar fuel catalysts with photosensitizers and construct light-harvesting antennae capable of achieving panchromatic absorption and directional energy concentration.

  @article{C2CS35223K, abstract = {Chemical ingenuity will play a significant role in solving the greatest challenge currently facing society: providing clean and carbon neutral energy for all of humanity. Molecular artificial photosynthesis is an emerging technology based on principles learned from Nature where individual components perform the essential light-harvesting{,} charge-separation{,} and water splitting functions to store solar energy in the form of chemical bonds. This tutorial review focuses specifically on the application of metallosupramolecular self-assembly strategies to interface solar fuel catalysts with photosensitizers and construct light-harvesting antennae capable of achieving panchromatic absorption and directional energy concentration.}, author = {Frischmann, Peter D. and Mahata, Kingsuk and Würthner, Frank}, journal = {Chem. Soc. Rev.}, keywords = {myown}, number = 4, pages = {1847-1870}, publisher = {The Royal Society of Chemistry}, title = {Powering the future of molecular artificial photosynthesis with light-harvesting metallosupramolecular dye assemblies}, volume = 42, year = 2013 }

  %0 Journal Article %1 C2CS35223K %A Frischmann, Peter D. %A Mahata, Kingsuk %A Würthner, Frank %D 2013 %I The Royal Society of Chemistry %J Chem. Soc. Rev. %N 4 %P 1847-1870 %R 10.1039/C2CS35223K %T Powering the future of molecular artificial photosynthesis with light-harvesting metallosupramolecular dye assemblies %U http://dx.doi.org/10.1039/C2CS35223K %V 42 %X Chemical ingenuity will play a significant role in solving the greatest challenge currently facing society: providing clean and carbon neutral energy for all of humanity. Molecular artificial photosynthesis is an emerging technology based on principles learned from Nature where individual components perform the essential light-harvesting, charge-separation, and water splitting functions to store solar energy in the form of chemical bonds. This tutorial review focuses specifically on the application of metallosupramolecular self-assembly strategies to interface solar fuel catalysts with photosensitizers and construct light-harvesting antennae capable of achieving panchromatic absorption and directional energy concentration.
• High-mobility organic thin-film transistors based on a small-molecule semiconductor deposited in vacuum and by solution shearing. Hofmockel, Robert; Zschieschang, Ute; Kraft, Ulrike; Rödel, Reinhold; Hansen, Nis Hauke; Stolte, Matthias; Würthner, Frank; Takimiya, Kazuo; Kern, Klaus; Pflaum, Jens; Klauk, Hagen. In Organic Electronics, 14(12), pp. 3213–3221. 2013.
  • [ Abstract ]
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  Abstract The small-molecule organic semiconductor 2,9-di-decyl-dinaphtho-[2,3-b:2′,3′-f]-thieno-[3,2-b]-thiophene (C10-DNTT) was used to fabricate bottom-gate, top-contact thin-film transistors (TFTs) in which the semiconductor layer was prepared either by vacuum deposition or by solution shearing. The maximum effective charge-carrier mobility of TFTs with vacuum-deposited C10-DNTT is 8.5cm2/Vs for a nominal semiconductor thickness of 10nm and a substrate temperature during the semiconductor deposition of 80°C. Scanning electron microscopy analysis reveals the growth of small, isolated islands that begin to coalesce into a flat conducting layer when the nominal thickness exceeds 4nm. The morphology of the vacuum-deposited semiconductor layers is dominated by tall lamellae that are formed during the deposition, except at very high substrate temperatures. Atomic force microscopy and X-ray diffraction measurements indicate that the C10-DNTT molecules stand approximately upright with respect to the substrate surface, both in the flat conducting layer near the surface and within the lamellae. Using the transmission line method on TFTs with channel lengths ranging from 10 to 100μm, a relatively small contact resistance of 0.33kΩcm was determined. TFTs with the C10-DNTT layer prepared by solution shearing exhibit a pronounced anisotropy of the electrical performance: TFTs with the channel oriented parallel to the shearing direction have an average carrier mobility of (2.8±0.3)cm2/Vs, while TFTs with the channel oriented perpendicular to the shearing direction have a somewhat smaller average mobility of (1.3±0.1)cm2/Vs.

  @article{HOFMOCKEL20133213, abstract = {Abstract The small-molecule organic semiconductor 2,9-di-decyl-dinaphtho-[2,3-b:2′,3′-f]-thieno-[3,2-b]-thiophene (C10-DNTT) was used to fabricate bottom-gate, top-contact thin-film transistors (TFTs) in which the semiconductor layer was prepared either by vacuum deposition or by solution shearing. The maximum effective charge-carrier mobility of TFTs with vacuum-deposited C10-DNTT is 8.5cm2/Vs for a nominal semiconductor thickness of 10nm and a substrate temperature during the semiconductor deposition of 80°C. Scanning electron microscopy analysis reveals the growth of small, isolated islands that begin to coalesce into a flat conducting layer when the nominal thickness exceeds 4nm. The morphology of the vacuum-deposited semiconductor layers is dominated by tall lamellae that are formed during the deposition, except at very high substrate temperatures. Atomic force microscopy and X-ray diffraction measurements indicate that the C10-DNTT molecules stand approximately upright with respect to the substrate surface, both in the flat conducting layer near the surface and within the lamellae. Using the transmission line method on TFTs with channel lengths ranging from 10 to 100μm, a relatively small contact resistance of 0.33kΩcm was determined. TFTs with the C10-DNTT layer prepared by solution shearing exhibit a pronounced anisotropy of the electrical performance: TFTs with the channel oriented parallel to the shearing direction have an average carrier mobility of (2.8±0.3)cm2/Vs, while TFTs with the channel oriented perpendicular to the shearing direction have a somewhat smaller average mobility of (1.3±0.1)cm2/Vs.}, author = {Hofmockel, Robert and Zschieschang, Ute and Kraft, Ulrike and Rödel, Reinhold and Hansen, Nis Hauke and Stolte, Matthias and Würthner, Frank and Takimiya, Kazuo and Kern, Klaus and Pflaum, Jens and Klauk, Hagen}, journal = {Organic Electronics}, keywords = {resistance}, number = 12, pages = {3213 - 3221}, title = {High-mobility organic thin-film transistors based on a small-molecule semiconductor deposited in vacuum and by solution shearing}, volume = 14, year = 2013 }

  %0 Journal Article %1 HOFMOCKEL20133213 %A Hofmockel, Robert %A Zschieschang, Ute %A Kraft, Ulrike %A Rödel, Reinhold %A Hansen, Nis Hauke %A Stolte, Matthias %A Würthner, Frank %A Takimiya, Kazuo %A Kern, Klaus %A Pflaum, Jens %A Klauk, Hagen %D 2013 %J Organic Electronics %N 12 %P 3213 - 3221 %R https://doi.org/10.1016/j.orgel.2013.09.003 %T High-mobility organic thin-film transistors based on a small-molecule semiconductor deposited in vacuum and by solution shearing %U http://www.sciencedirect.com/science/article/pii/S1566119913003923 %V 14 %X Abstract The small-molecule organic semiconductor 2,9-di-decyl-dinaphtho-[2,3-b:2′,3′-f]-thieno-[3,2-b]-thiophene (C10-DNTT) was used to fabricate bottom-gate, top-contact thin-film transistors (TFTs) in which the semiconductor layer was prepared either by vacuum deposition or by solution shearing. The maximum effective charge-carrier mobility of TFTs with vacuum-deposited C10-DNTT is 8.5cm2/Vs for a nominal semiconductor thickness of 10nm and a substrate temperature during the semiconductor deposition of 80°C. Scanning electron microscopy analysis reveals the growth of small, isolated islands that begin to coalesce into a flat conducting layer when the nominal thickness exceeds 4nm. The morphology of the vacuum-deposited semiconductor layers is dominated by tall lamellae that are formed during the deposition, except at very high substrate temperatures. Atomic force microscopy and X-ray diffraction measurements indicate that the C10-DNTT molecules stand approximately upright with respect to the substrate surface, both in the flat conducting layer near the surface and within the lamellae. Using the transmission line method on TFTs with channel lengths ranging from 10 to 100μm, a relatively small contact resistance of 0.33kΩcm was determined. TFTs with the C10-DNTT layer prepared by solution shearing exhibit a pronounced anisotropy of the electrical performance: TFTs with the channel oriented parallel to the shearing direction have an average carrier mobility of (2.8±0.3)cm2/Vs, while TFTs with the channel oriented perpendicular to the shearing direction have a somewhat smaller average mobility of (1.3±0.1)cm2/Vs.
• Regioselectivity in Sequential Nucleophilic Substitution of Tetrabromonaphthalene Diimides. Suraru, Sabin-Lucian; Würthner, Frank. In The Journal of Organic Chemistry, 78(11), pp. 5227–5238. 2013.

  PMID: 23631803
  • [ Abstract ]
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  Nucleophilic substitution of tetrabromosubstituted naphthalene diimides (NDIs) with aniline was studied in detail to explore the regioselectivity as three different diamino-substituted regioisomeric products can be formed. We found that the regioselectivity of the nucleophilic disubstitution of 2,3,6,7-tetrabromonaphthalene diimide with aniline is dependent on reaction solvents and additives. In dichloromethane and chloroform without an additive the 2,7-diamino-3,6-dibromo-NDI isomer was formed regioselectively, while in DMF under similar reaction conditions the 2,3-diamino-6,7-dibromo isomer was observed as the major regioisomer. The third possible regioisomer 2,6-diamino-3,7-dibromo product was formed, if at all, in an insignificant amount. Tetrabutylammonium fluoride (TBAF) additive exerts a dramatic effect on the regioselectivity of this reaction, as in dichloromethane without TBAF the 2,7-diamino isomer was formed regioselectively, while without TBAF the 2,3-diamino isomer was formed exclusively. This remarkable effect of TBAF can be rationalized in terms of a deprotonation of the monoamino-tribromo-NDI generated in the first step of this sequential reaction as an intermediate by fluoride ions leading to an anionic species as indicated by UV–vis and NMR experiments whose electronic properties direct the regioselective attack of the second amine molecule. Our efforts led to the exclusively regioselective synthesis of 2,7-diamino-3,6-dibromo- and 2,3-diamino-6,7-dibromo-NDIs for the first time.

  @article{doi:10.1021/jo400320a, abstract = {Nucleophilic substitution of tetrabromosubstituted naphthalene diimides (NDIs) with aniline was studied in detail to explore the regioselectivity as three different diamino-substituted regioisomeric products can be formed. We found that the regioselectivity of the nucleophilic disubstitution of 2,3,6,7-tetrabromonaphthalene diimide with aniline is dependent on reaction solvents and additives. In dichloromethane and chloroform without an additive the 2,7-diamino-3,6-dibromo-NDI isomer was formed regioselectively, while in DMF under similar reaction conditions the 2,3-diamino-6,7-dibromo isomer was observed as the major regioisomer. The third possible regioisomer 2,6-diamino-3,7-dibromo product was formed, if at all, in an insignificant amount. Tetrabutylammonium fluoride (TBAF) additive exerts a dramatic effect on the regioselectivity of this reaction, as in dichloromethane without TBAF the 2,7-diamino isomer was formed regioselectively, while without TBAF the 2,3-diamino isomer was formed exclusively. This remarkable effect of TBAF can be rationalized in terms of a deprotonation of the monoamino-tribromo-NDI generated in the first step of this sequential reaction as an intermediate by fluoride ions leading to an anionic species as indicated by UV–vis and NMR experiments whose electronic properties direct the regioselective attack of the second amine molecule. Our efforts led to the exclusively regioselective synthesis of 2,7-diamino-3,6-dibromo- and 2,3-diamino-6,7-dibromo-NDIs for the first time.}, author = {Suraru, Sabin-Lucian and Würthner, Frank}, journal = {The Journal of Organic Chemistry}, keywords = {myown}, note = {PMID: 23631803}, number = 11, pages = {5227-5238}, title = {Regioselectivity in Sequential Nucleophilic Substitution of Tetrabromonaphthalene Diimides}, volume = 78, year = 2013 }

  %0 Journal Article %1 doi:10.1021/jo400320a %A Suraru, Sabin-Lucian %A Würthner, Frank %D 2013 %J The Journal of Organic Chemistry %N 11 %P 5227-5238 %R 10.1021/jo400320a %T Regioselectivity in Sequential Nucleophilic Substitution of Tetrabromonaphthalene Diimides %U http://dx.doi.org/10.1021/jo400320a %V 78 %X Nucleophilic substitution of tetrabromosubstituted naphthalene diimides (NDIs) with aniline was studied in detail to explore the regioselectivity as three different diamino-substituted regioisomeric products can be formed. We found that the regioselectivity of the nucleophilic disubstitution of 2,3,6,7-tetrabromonaphthalene diimide with aniline is dependent on reaction solvents and additives. In dichloromethane and chloroform without an additive the 2,7-diamino-3,6-dibromo-NDI isomer was formed regioselectively, while in DMF under similar reaction conditions the 2,3-diamino-6,7-dibromo isomer was observed as the major regioisomer. The third possible regioisomer 2,6-diamino-3,7-dibromo product was formed, if at all, in an insignificant amount. Tetrabutylammonium fluoride (TBAF) additive exerts a dramatic effect on the regioselectivity of this reaction, as in dichloromethane without TBAF the 2,7-diamino isomer was formed regioselectively, while without TBAF the 2,3-diamino isomer was formed exclusively. This remarkable effect of TBAF can be rationalized in terms of a deprotonation of the monoamino-tribromo-NDI generated in the first step of this sequential reaction as an intermediate by fluoride ions leading to an anionic species as indicated by UV–vis and NMR experiments whose electronic properties direct the regioselective attack of the second amine molecule. Our efforts led to the exclusively regioselective synthesis of 2,7-diamino-3,6-dibromo- and 2,3-diamino-6,7-dibromo-NDIs for the first time.
• Biphasic Self-Assembly Pathways and Size-Dependent Photophysical Properties of Perylene Bisimide Dye Aggregates. Fennel, Franziska; Wolter, Steffen; Xie, Zengqi; Plötz, Per-Arno; Kühn, Oliver; Würthner, Frank; Lochbrunner, Stefan. In J. Am. Chem. Soc., 135(50), pp. 18722–18725. 2013.
  • [ Abstract ]
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  • [ DOI ]
  The concentration-dependent absorption and temperature-dependent fluorescence of the perylene bisimide dye PBI 1 in methylcyclohexane point to a biphasic aggregation behavior. At intermediate concentrations and temperatures, respectively, a dimer with low fluorescence yield dominates, which cannot be extended to longer aggregates. Those are formed at high concentrations and low temperatures, respectively, via a second, energetically unfavorable dimer species that acts as a nucleus. A corresponding aggregation model reproduces accurately the concentration dependence and allows extracting the equilibrium constants and spectra of the distinct species. The differences in the photophysical properties indicate H-type excitonic coupling for the favored dimer and J-type characteristics for the extended aggregates which could be related to structural models based on DFT calculations. The energetics can be understood by considering hydrogen-bonding and π–π-stacking interactions.

  @article{doi:10.1021/ja409597x, abstract = {The concentration-dependent absorption and temperature-dependent fluorescence of the perylene bisimide dye PBI 1 in methylcyclohexane point to a biphasic aggregation behavior. At intermediate concentrations and temperatures, respectively, a dimer with low fluorescence yield dominates, which cannot be extended to longer aggregates. Those are formed at high concentrations and low temperatures, respectively, via a second, energetically unfavorable dimer species that acts as a nucleus. A corresponding aggregation model reproduces accurately the concentration dependence and allows extracting the equilibrium constants and spectra of the distinct species. The differences in the photophysical properties indicate H-type excitonic coupling for the favored dimer and J-type characteristics for the extended aggregates which could be related to structural models based on DFT calculations. The energetics can be understood by considering hydrogen-bonding and π–π-stacking interactions.}, author = {Fennel, Franziska and Wolter, Steffen and Xie, Zengqi and Plötz, Per-Arno and Kühn, Oliver and Würthner, Frank and Lochbrunner, Stefan}, journal = {J. Am. Chem. Soc.}, keywords = {myown}, number = 50, pages = {18722-18725}, title = {Biphasic Self-Assembly Pathways and Size-Dependent Photophysical Properties of Perylene Bisimide Dye Aggregates}, volume = 135, year = 2013 }

  %0 Journal Article %1 doi:10.1021/ja409597x %A Fennel, Franziska %A Wolter, Steffen %A Xie, Zengqi %A Plötz, Per-Arno %A Kühn, Oliver %A Würthner, Frank %A Lochbrunner, Stefan %D 2013 %J J. Am. Chem. Soc. %N 50 %P 18722-18725 %R 10.1021/ja409597x %T Biphasic Self-Assembly Pathways and Size-Dependent Photophysical Properties of Perylene Bisimide Dye Aggregates %U http://dx.doi.org/10.1021/ja409597x %V 135 %X The concentration-dependent absorption and temperature-dependent fluorescence of the perylene bisimide dye PBI 1 in methylcyclohexane point to a biphasic aggregation behavior. At intermediate concentrations and temperatures, respectively, a dimer with low fluorescence yield dominates, which cannot be extended to longer aggregates. Those are formed at high concentrations and low temperatures, respectively, via a second, energetically unfavorable dimer species that acts as a nucleus. A corresponding aggregation model reproduces accurately the concentration dependence and allows extracting the equilibrium constants and spectra of the distinct species. The differences in the photophysical properties indicate H-type excitonic coupling for the favored dimer and J-type characteristics for the extended aggregates which could be related to structural models based on DFT calculations. The energetics can be understood by considering hydrogen-bonding and π–π-stacking interactions.
• Chlorophyll J-Aggregates: From Bioinspired Dye Stacks to Nanotubes, Liquid Crystals, and Biosupramolecular Electronics. Sengupta, Sanchita; Würthner, Frank. In Accounts of Chemical Research, 46(11), pp. 2498–2512. 2013.

  PMID: 23865851
  • [ Abstract ]
  • [ BibTeX ]
  • [ EndNote ]
  • [ DOI ]
  Among the natural light-harvesting (LH) systems, those of green sulfur and nonsulfur photosynthetic bacteria are exceptional because they lack the support of a protein matrix. Instead, these so-called chlorosomes are based solely on “pigments”. These are self-assembled bacteriochlorophyll c, d, and e derivatives, which consist of a chlorophyll skeleton bearing a 31-hydroxy functional group. Chemists consider the latter as an essential structural unit to direct the formation of light-harvesting self-assembled dye aggregates with J-type excitonic coupling. The intriguing properties of chlorosomal J-type aggregates, particularly narrow red-shifted absorption bands, compared with monomers and their ability to delocalize and migrate excitons, have inspired intense research activities toward synthetic analogues in this field. The ultimate goal of this research field is the development of (opto-)electronic devices based on the architectural principle of chlorosomal LH systems. In this regard, the challenge is to develop small, functional building blocks with appropriate substituents that are preprogrammed to self-assemble across different length scales and to emulate functions of natural LH systems or to realize entirely new functions beyond those found in nature. In this Account, we highlight our achievements in the past decade with semisynthetic zinc chlorins (ZnChls) as model compounds of bacteriochlorophylls obtained from the naturally most abundant chlorin precursor: chlorophyll a.To begin, we explore how supramolecular strategies involving π-stacking, hydrogen bonding, and metal–oxygen coordination can be used to design ZnChl-based molecular stack, tube, and liquid crystalline assemblies conducive to charge and energy transport. Our design principle is based on the bioinspired functionalization of the 31-position of ZnChl with a hydroxy or methoxy group; the former gives rise to tubular assemblies, whereas the latter induces stack assemblies. Functionalization of the 172-position with esterified hydrophilic or hydrophobic chains, dendron-wedge substituents, and chromophores having complementary optical properties such as naphthalene bisimides (NBIs) is used to modulate the self-assembly of ZnChl dyes. The resulting assemblies exhibit enhanced charge transport and energy transfer abilities. We have used UV/vis, circular dichroism (CD), fluorescence spectroscopy, and dynamic light scattering (DLS) for the characterization of these assemblies in solution. In addition, we have studied assembly morphologies by atomic force microscopy (AFM), scanning tunneling microscopy (STM), transmission electron microscopy (TEM), and cryogenic-TEM. Crystallographic techniques such as powder X-ray and solid-state NMR have been used to explain the precise long- and short-range packing of dyes in these assemblies. Finally, functional properties such as charge and energy transport have been explored by pulse radiolysis time-resolved microwave conductivity (PR-TRMC), conductive AFM, and time-resolved fluorescence spectroscopy. The design principles discussed in this Account are important steps toward the utilization of these materials in biosupramolecular electronics and photonics in the future.

  @article{doi:10.1021/ar400017u, abstract = {Among the natural light-harvesting (LH) systems, those of green sulfur and nonsulfur photosynthetic bacteria are exceptional because they lack the support of a protein matrix. Instead, these so-called chlorosomes are based solely on “pigments”. These are self-assembled bacteriochlorophyll c, d, and e derivatives, which consist of a chlorophyll skeleton bearing a 31-hydroxy functional group. Chemists consider the latter as an essential structural unit to direct the formation of light-harvesting self-assembled dye aggregates with J-type excitonic coupling. The intriguing properties of chlorosomal J-type aggregates, particularly narrow red-shifted absorption bands, compared with monomers and their ability to delocalize and migrate excitons, have inspired intense research activities toward synthetic analogues in this field. The ultimate goal of this research field is the development of (opto-)electronic devices based on the architectural principle of chlorosomal LH systems. In this regard, the challenge is to develop small, functional building blocks with appropriate substituents that are preprogrammed to self-assemble across different length scales and to emulate functions of natural LH systems or to realize entirely new functions beyond those found in nature. In this Account, we highlight our achievements in the past decade with semisynthetic zinc chlorins (ZnChls) as model compounds of bacteriochlorophylls obtained from the naturally most abundant chlorin precursor: chlorophyll a.To begin, we explore how supramolecular strategies involving π-stacking, hydrogen bonding, and metal–oxygen coordination can be used to design ZnChl-based molecular stack, tube, and liquid crystalline assemblies conducive to charge and energy transport. Our design principle is based on the bioinspired functionalization of the 31-position of ZnChl with a hydroxy or methoxy group; the former gives rise to tubular assemblies, whereas the latter induces stack assemblies. Functionalization of the 172-position with esterified hydrophilic or hydrophobic chains, dendron-wedge substituents, and chromophores having complementary optical properties such as naphthalene bisimides (NBIs) is used to modulate the self-assembly of ZnChl dyes. The resulting assemblies exhibit enhanced charge transport and energy transfer abilities. We have used UV/vis, circular dichroism (CD), fluorescence spectroscopy, and dynamic light scattering (DLS) for the characterization of these assemblies in solution. In addition, we have studied assembly morphologies by atomic force microscopy (AFM), scanning tunneling microscopy (STM), transmission electron microscopy (TEM), and cryogenic-TEM. Crystallographic techniques such as powder X-ray and solid-state NMR have been used to explain the precise long- and short-range packing of dyes in these assemblies. Finally, functional properties such as charge and energy transport have been explored by pulse radiolysis time-resolved microwave conductivity (PR-TRMC), conductive AFM, and time-resolved fluorescence spectroscopy. The design principles discussed in this Account are important steps toward the utilization of these materials in biosupramolecular electronics and photonics in the future.}, author = {Sengupta, Sanchita and Würthner, Frank}, journal = {Accounts of Chemical Research}, keywords = {myown}, note = {PMID: 23865851}, number = 11, pages = {2498-2512}, title = {Chlorophyll J-Aggregates: From Bioinspired Dye Stacks to Nanotubes, Liquid Crystals, and Biosupramolecular Electronics}, volume = 46, year = 2013 }

  %0 Journal Article %1 doi:10.1021/ar400017u %A Sengupta, Sanchita %A Würthner, Frank %D 2013 %J Accounts of Chemical Research %N 11 %P 2498-2512 %R 10.1021/ar400017u %T Chlorophyll J-Aggregates: From Bioinspired Dye Stacks to Nanotubes, Liquid Crystals, and Biosupramolecular Electronics %U http://dx.doi.org/10.1021/ar400017u %V 46 %X Among the natural light-harvesting (LH) systems, those of green sulfur and nonsulfur photosynthetic bacteria are exceptional because they lack the support of a protein matrix. Instead, these so-called chlorosomes are based solely on “pigments”. These are self-assembled bacteriochlorophyll c, d, and e derivatives, which consist of a chlorophyll skeleton bearing a 31-hydroxy functional group. Chemists consider the latter as an essential structural unit to direct the formation of light-harvesting self-assembled dye aggregates with J-type excitonic coupling. The intriguing properties of chlorosomal J-type aggregates, particularly narrow red-shifted absorption bands, compared with monomers and their ability to delocalize and migrate excitons, have inspired intense research activities toward synthetic analogues in this field. The ultimate goal of this research field is the development of (opto-)electronic devices based on the architectural principle of chlorosomal LH systems. In this regard, the challenge is to develop small, functional building blocks with appropriate substituents that are preprogrammed to self-assemble across different length scales and to emulate functions of natural LH systems or to realize entirely new functions beyond those found in nature. In this Account, we highlight our achievements in the past decade with semisynthetic zinc chlorins (ZnChls) as model compounds of bacteriochlorophylls obtained from the naturally most abundant chlorin precursor: chlorophyll a.To begin, we explore how supramolecular strategies involving π-stacking, hydrogen bonding, and metal–oxygen coordination can be used to design ZnChl-based molecular stack, tube, and liquid crystalline assemblies conducive to charge and energy transport. Our design principle is based on the bioinspired functionalization of the 31-position of ZnChl with a hydroxy or methoxy group; the former gives rise to tubular assemblies, whereas the latter induces stack assemblies. Functionalization of the 172-position with esterified hydrophilic or hydrophobic chains, dendron-wedge substituents, and chromophores having complementary optical properties such as naphthalene bisimides (NBIs) is used to modulate the self-assembly of ZnChl dyes. The resulting assemblies exhibit enhanced charge transport and energy transfer abilities. We have used UV/vis, circular dichroism (CD), fluorescence spectroscopy, and dynamic light scattering (DLS) for the characterization of these assemblies in solution. In addition, we have studied assembly morphologies by atomic force microscopy (AFM), scanning tunneling microscopy (STM), transmission electron microscopy (TEM), and cryogenic-TEM. Crystallographic techniques such as powder X-ray and solid-state NMR have been used to explain the precise long- and short-range packing of dyes in these assemblies. Finally, functional properties such as charge and energy transport have been explored by pulse radiolysis time-resolved microwave conductivity (PR-TRMC), conductive AFM, and time-resolved fluorescence spectroscopy. The design principles discussed in this Account are important steps toward the utilization of these materials in biosupramolecular electronics and photonics in the future.
• ToF-SIMS of metal-complex-based supramolecular architectures on oxide surfaces. Spampinato, V.; Vitale, S.; Quici, S.; Torrisi, A.; Stepanenko, V.; Würthner, F.; Licciardello, A. In Surface and Interface Analysis, 45(1), pp. 206–210. 2013.
  • [ Abstract ]
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  Time-of-flight secondary ion mass spectrometry (ToF-SIMS) was applied in combination with optical absorption spectroscopy for studying the anchoring of polypyridine-based supramolecular layers on oxide surfaces, such as quartz or indium tin oxide, by means of a layer-by-layer method involving a self-assembly process relying on coordination interactions that lead to the formation, at the surface, of metal-complex-based layers. ToF-SIMS measurements were crucial in setting up the strategy for the preparation of the above systems, as they allowed a detailed monitoring of each preparation step and provided direct qualitative information on the successful anchoring at the surface. Optical measurements, on the other hand, provided quantitative information on the growth of the multilayers, beyond the thickness sampled by static-SIMS. Copyright © 2012 John Wiley & Sons, Ltd.

  @article{SIA:SIA5123, abstract = {Time-of-flight secondary ion mass spectrometry (ToF-SIMS) was applied in combination with optical absorption spectroscopy for studying the anchoring of polypyridine-based supramolecular layers on oxide surfaces, such as quartz or indium tin oxide, by means of a layer-by-layer method involving a self-assembly process relying on coordination interactions that lead to the formation, at the surface, of metal-complex-based layers. ToF-SIMS measurements were crucial in setting up the strategy for the preparation of the above systems, as they allowed a detailed monitoring of each preparation step and provided direct qualitative information on the successful anchoring at the surface. Optical measurements, on the other hand, provided quantitative information on the growth of the multilayers, beyond the thickness sampled by static-SIMS. Copyright © 2012 John Wiley & Sons, Ltd.}, author = {Spampinato, V. and Vitale, S. and Quici, S. and Torrisi, A. and Stepanenko, V. and Würthner, F. and Licciardello, A.}, journal = {Surface and Interface Analysis}, keywords = {myown}, number = 1, pages = {206–210}, title = {ToF-SIMS of metal-complex-based supramolecular architectures on oxide surfaces}, volume = 45, year = 2013 }

  %0 Journal Article %1 SIA:SIA5123 %A Spampinato, V. %A Vitale, S. %A Quici, S. %A Torrisi, A. %A Stepanenko, V. %A Würthner, F. %A Licciardello, A. %D 2013 %J Surface and Interface Analysis %N 1 %P 206--210 %R 10.1002/sia.5123 %T ToF-SIMS of metal-complex-based supramolecular architectures on oxide surfaces %U http://dx.doi.org/10.1002/sia.5123 %V 45 %X Time-of-flight secondary ion mass spectrometry (ToF-SIMS) was applied in combination with optical absorption spectroscopy for studying the anchoring of polypyridine-based supramolecular layers on oxide surfaces, such as quartz or indium tin oxide, by means of a layer-by-layer method involving a self-assembly process relying on coordination interactions that lead to the formation, at the surface, of metal-complex-based layers. ToF-SIMS measurements were crucial in setting up the strategy for the preparation of the above systems, as they allowed a detailed monitoring of each preparation step and provided direct qualitative information on the successful anchoring at the surface. Optical measurements, on the other hand, provided quantitative information on the growth of the multilayers, beyond the thickness sampled by static-SIMS. Copyright © 2012 John Wiley & Sons, Ltd.
• Cooperative Supramolecular Polymerization: Comparison of Different Models Applied on the Self-Assembly of Bis(merocyanine) Dyes. Fernández, Gustavo; Stolte, Matthias; Stepanenko, Vladimir; Würthner, Frank. In Chemistry – A European Journal, 19(1), pp. 206–217. 2013.
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  Three new molecular building blocks 1 a–c for supramolecular polymerization are described that feature two dipolar merocyanine dyes tethered by p-xylylene spacers. Concentration- and temperature-dependent UV/Vis spectroscopy in chloroform combined with dynamic light scattering, capillary viscosimetry and atomic force microscopy investigations were applied to elucidate the mechanistic features of the self-assembly of these strongly dipolar dyes. Our detailed studies reveal that the self-assembly is very pronounced for bis(merocyanines) 1 a,b bearing linear alkyl chains, but completely absent for bis(merocyanine) 1 c bearing sterically more bulky ethylhexyl substituents. Both temperature- and concentration-dependent UV/Vis data provide unambiguous evidence for a cooperative self-assembly process for bis(merocyanines) 1 a,b, which was analyzed in detail by the Meijer–Schenning–Van-der-Schoot model (applicable to temperature-dependent data) and by the Goldstein–Stryer model (applicable to concentration-dependent data). By combining both methods all parameters of interest to understand the self-assembly process could be derived, including in particular the nucleus size (8–10 monomeric units), the cooperativity factor (ca. 0.006), and the nucleation and elongation constants of about 103 and 106 M−1 in chloroform at room temperature, respectively.

  @article{CHEM:CHEM201202679, abstract = {Three new molecular building blocks 1 a–c for supramolecular polymerization are described that feature two dipolar merocyanine dyes tethered by p-xylylene spacers. Concentration- and temperature-dependent UV/Vis spectroscopy in chloroform combined with dynamic light scattering, capillary viscosimetry and atomic force microscopy investigations were applied to elucidate the mechanistic features of the self-assembly of these strongly dipolar dyes. Our detailed studies reveal that the self-assembly is very pronounced for bis(merocyanines) 1 a,b bearing linear alkyl chains, but completely absent for bis(merocyanine) 1 c bearing sterically more bulky ethylhexyl substituents. Both temperature- and concentration-dependent UV/Vis data provide unambiguous evidence for a cooperative self-assembly process for bis(merocyanines) 1 a,b, which was analyzed in detail by the Meijer–Schenning–Van-der-Schoot model (applicable to temperature-dependent data) and by the Goldstein–Stryer model (applicable to concentration-dependent data). By combining both methods all parameters of interest to understand the self-assembly process could be derived, including in particular the nucleus size (8–10 monomeric units), the cooperativity factor (ca. 0.006), and the nucleation and elongation constants of about 103 and 106 M−1 in chloroform at room temperature, respectively.}, author = {Fernández, Gustavo and Stolte, Matthias and Stepanenko, Vladimir and Würthner, Frank}, journal = {Chemistry – A European Journal}, keywords = {myown}, number = 1, pages = {206–217}, publisher = {WILEY-VCH Verlag}, title = {Cooperative Supramolecular Polymerization: Comparison of Different Models Applied on the Self-Assembly of Bis(merocyanine) Dyes}, volume = 19, year = 2013 }

  %0 Journal Article %1 CHEM:CHEM201202679 %A Fernández, Gustavo %A Stolte, Matthias %A Stepanenko, Vladimir %A Würthner, Frank %D 2013 %I WILEY-VCH Verlag %J Chemistry – A European Journal %N 1 %P 206--217 %R 10.1002/chem.201202679 %T Cooperative Supramolecular Polymerization: Comparison of Different Models Applied on the Self-Assembly of Bis(merocyanine) Dyes %U http://dx.doi.org/10.1002/chem.201202679 %V 19 %X Three new molecular building blocks 1 a–c for supramolecular polymerization are described that feature two dipolar merocyanine dyes tethered by p-xylylene spacers. Concentration- and temperature-dependent UV/Vis spectroscopy in chloroform combined with dynamic light scattering, capillary viscosimetry and atomic force microscopy investigations were applied to elucidate the mechanistic features of the self-assembly of these strongly dipolar dyes. Our detailed studies reveal that the self-assembly is very pronounced for bis(merocyanines) 1 a,b bearing linear alkyl chains, but completely absent for bis(merocyanine) 1 c bearing sterically more bulky ethylhexyl substituents. Both temperature- and concentration-dependent UV/Vis data provide unambiguous evidence for a cooperative self-assembly process for bis(merocyanines) 1 a,b, which was analyzed in detail by the Meijer–Schenning–Van-der-Schoot model (applicable to temperature-dependent data) and by the Goldstein–Stryer model (applicable to concentration-dependent data). By combining both methods all parameters of interest to understand the self-assembly process could be derived, including in particular the nucleus size (8–10 monomeric units), the cooperativity factor (ca. 0.006), and the nucleation and elongation constants of about 103 and 106 M−1 in chloroform at room temperature, respectively.
• Charge transport through perylene bisimide molecular junctions: An electrochemical approach. Li, Chen; Stepanenko, Vladimir; Lin, Mei-Jin; Hong, Wenjing; Würthner, Frank; Wandlowski, Thomas. In physica status solidi (b), 250(11), pp. 2458–2467. 2013.
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  Single molecular junction conductances of a family of five symmetric and two unsymmetric perylene tetracarboxylic bisimides (PBI) with variable bay-area substituents were studied employing a scanning tunneling microscope (STM)-based break junction technique. The stretching experiments provide clear evidence for the formation of single molecular junctions and π–π stacked dimers. Electrolyte gating demonstrates a distinct gating effect in symmetric molecular junctions, which strongly depends on molecular structure and properties of the solvent/electrolyte. Weak π–π-coupling in the unsymmetric dimers prevents rectification.

  @article{PSSB:PSSB201350034, abstract = {Single molecular junction conductances of a family of five symmetric and two unsymmetric perylene tetracarboxylic bisimides (PBI) with variable bay-area substituents were studied employing a scanning tunneling microscope (STM)-based break junction technique. The stretching experiments provide clear evidence for the formation of single molecular junctions and π–π stacked dimers. Electrolyte gating demonstrates a distinct gating effect in symmetric molecular junctions, which strongly depends on molecular structure and properties of the solvent/electrolyte. Weak π–π-coupling in the unsymmetric dimers prevents rectification.}, author = {Li, Chen and Stepanenko, Vladimir and Lin, Mei-Jin and Hong, Wenjing and Würthner, Frank and Wandlowski, Thomas}, journal = {physica status solidi (b)}, keywords = {myown}, number = 11, pages = {2458–2467}, title = {Charge transport through perylene bisimide molecular junctions: An electrochemical approach}, volume = 250, year = 2013 }

  %0 Journal Article %1 PSSB:PSSB201350034 %A Li, Chen %A Stepanenko, Vladimir %A Lin, Mei-Jin %A Hong, Wenjing %A Würthner, Frank %A Wandlowski, Thomas %D 2013 %J physica status solidi (b) %N 11 %P 2458--2467 %R 10.1002/pssb.201350034 %T Charge transport through perylene bisimide molecular junctions: An electrochemical approach %U http://dx.doi.org/10.1002/pssb.201350034 %V 250 %X Single molecular junction conductances of a family of five symmetric and two unsymmetric perylene tetracarboxylic bisimides (PBI) with variable bay-area substituents were studied employing a scanning tunneling microscope (STM)-based break junction technique. The stretching experiments provide clear evidence for the formation of single molecular junctions and π–π stacked dimers. Electrolyte gating demonstrates a distinct gating effect in symmetric molecular junctions, which strongly depends on molecular structure and properties of the solvent/electrolyte. Weak π–π-coupling in the unsymmetric dimers prevents rectification.
• Influence of Merocyanine Molecular Dipole Moments on the Valence Levels in Thin Films and the Interface Energy Level Alignment with Au(111). Krause, Stefan; Stolte, Matthias; Würthner, Frank; Koch, Norbert. In J. Phys. Chem. C., 117(37), pp. 19031–19037. 2013.
  • [ Abstract ]
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  We study the effect of increasing permanent dipole moment of four dipolar merocyanine dyes on the energy level alignment with Au(111) and the energy levels in thin films with ultraviolet (UV) photoemission spectroscopy. Preceding X-ray diffraction experiments showed that these dipolar molecules form centrosymmetric dimeric units in their bulk crystal structure. The effect of dimerization was also seen in a splitting of the highest occupied level of bilayers and thin films of all four molecules. This split into two components due to intermolecular electronic coupling between two merocyanines is estimated to be 0.2–0.3 eV. Monolayer films on Au(111) did not exhibit such splitting due to a different adsorption structure. A significant ultraviolet radiation sensitivity of the dyes near the metal surface was noticed. Unlike other radiation-sensitive compounds, the reason for molecule damage is related to the secondary electrons produced in the metal substrate during photoelectron spectroscopy measurements and not to the UV radiation itself.

  @article{doi:10.1021/jp4060395, abstract = {We study the effect of increasing permanent dipole moment of four dipolar merocyanine dyes on the energy level alignment with Au(111) and the energy levels in thin films with ultraviolet (UV) photoemission spectroscopy. Preceding X-ray diffraction experiments showed that these dipolar molecules form centrosymmetric dimeric units in their bulk crystal structure. The effect of dimerization was also seen in a splitting of the highest occupied level of bilayers and thin films of all four molecules. This split into two components due to intermolecular electronic coupling between two merocyanines is estimated to be 0.2–0.3 eV. Monolayer films on Au(111) did not exhibit such splitting due to a different adsorption structure. A significant ultraviolet radiation sensitivity of the dyes near the metal surface was noticed. Unlike other radiation-sensitive compounds, the reason for molecule damage is related to the secondary electrons produced in the metal substrate during photoelectron spectroscopy measurements and not to the UV radiation itself.}, author = {Krause, Stefan and Stolte, Matthias and Würthner, Frank and Koch, Norbert}, journal = {J. Phys. Chem. C.}, keywords = {myown}, number = 37, pages = {19031-19037}, title = {Influence of Merocyanine Molecular Dipole Moments on the Valence Levels in Thin Films and the Interface Energy Level Alignment with Au(111)}, volume = 117, year = 2013 }

  %0 Journal Article %1 doi:10.1021/jp4060395 %A Krause, Stefan %A Stolte, Matthias %A Würthner, Frank %A Koch, Norbert %D 2013 %J J. Phys. Chem. C. %N 37 %P 19031-19037 %R 10.1021/jp4060395 %T Influence of Merocyanine Molecular Dipole Moments on the Valence Levels in Thin Films and the Interface Energy Level Alignment with Au(111) %U http://dx.doi.org/10.1021/jp4060395 %V 117 %X We study the effect of increasing permanent dipole moment of four dipolar merocyanine dyes on the energy level alignment with Au(111) and the energy levels in thin films with ultraviolet (UV) photoemission spectroscopy. Preceding X-ray diffraction experiments showed that these dipolar molecules form centrosymmetric dimeric units in their bulk crystal structure. The effect of dimerization was also seen in a splitting of the highest occupied level of bilayers and thin films of all four molecules. This split into two components due to intermolecular electronic coupling between two merocyanines is estimated to be 0.2–0.3 eV. Monolayer films on Au(111) did not exhibit such splitting due to a different adsorption structure. A significant ultraviolet radiation sensitivity of the dyes near the metal surface was noticed. Unlike other radiation-sensitive compounds, the reason for molecule damage is related to the secondary electrons produced in the metal substrate during photoelectron spectroscopy measurements and not to the UV radiation itself.
• Backbone-Directed Perylene Dye Self-Assembly into Oligomer Stacks. Shao, Changzhun; Stolte, Matthias; Würthner, Frank. In Angew. Chem. Int. Ed., 52, pp. 10463–10467. 2013.
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  @article{ANGE:ANGE201305894, author = {Shao, Changzhun and Stolte, Matthias and Würthner, Frank}, journal = {Angew. Chem. Int. Ed.}, keywords = {myown}, pages = {10463-10467}, publisher = {WILEY-VCH Verlag}, title = {Backbone-Directed Perylene Dye Self-Assembly into Oligomer Stacks}, volume = 52, year = 2013 }

  %0 Journal Article %1 ANGE:ANGE201305894 %A Shao, Changzhun %A Stolte, Matthias %A Würthner, Frank %D 2013 %I WILEY-VCH Verlag %J Angew. Chem. Int. Ed. %P 10463-10467 %R 10.1002/anie.201305894 %T Backbone-Directed Perylene Dye Self-Assembly into Oligomer Stacks %U https://onlinelibrary.wiley.com/doi/full/10.1002/anie.201305894 %V 52
• White-light emitting dye micelles in aqueous solution. Zhang, Xin; Gorl, Daniel; Würthner, Frank. In Chem. Commun., 49(74), pp. 8178–8180. 2013.
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  Biscarbazole-loaded perylene bisimide (PBI) dye micelles in water afforded a fluorescence resonance energy transfer (FRET)-based white-light emitting nano luminary system with biscarbazoles as energy donors and PBI micelles as acceptors.

  @article{C3CC44875D, abstract = {Biscarbazole-loaded perylene bisimide (PBI) dye micelles in water afforded a fluorescence resonance energy transfer (FRET)-based white-light emitting nano luminary system with biscarbazoles as energy donors and PBI micelles as acceptors.}, author = {Zhang, Xin and Gorl, Daniel and Würthner, Frank}, journal = {Chem. Commun.}, keywords = {myown}, number = 74, pages = {8178-8180}, publisher = {The Royal Society of Chemistry}, title = {White-light emitting dye micelles in aqueous solution}, volume = 49, year = 2013 }

  %0 Journal Article %1 C3CC44875D %A Zhang, Xin %A Gorl, Daniel %A Würthner, Frank %D 2013 %I The Royal Society of Chemistry %J Chem. Commun. %N 74 %P 8178-8180 %R 10.1039/C3CC44875D %T White-light emitting dye micelles in aqueous solution %U http://dx.doi.org/10.1039/C3CC44875D %V 49 %X Biscarbazole-loaded perylene bisimide (PBI) dye micelles in water afforded a fluorescence resonance energy transfer (FRET)-based white-light emitting nano luminary system with biscarbazoles as energy donors and PBI micelles as acceptors.
• Quadruple π Stack of Two Perylene Bisimide Tweezers: A Bimolecular Complex with Kinetic Stability. Shao, Changzhun; Stolte, Matthias; Würthner, Frank. In Angew. Chem. Int. Ed., 52(29), pp. 7482–7486. 2013.
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  @article{ANIE:ANIE201302479, author = {Shao, Changzhun and Stolte, Matthias and Würthner, Frank}, journal = {Angew. Chem. Int. Ed.}, keywords = {myown}, number = 29, pages = {7482–7486}, publisher = {WILEY-VCH Verlag}, title = {Quadruple π Stack of Two Perylene Bisimide Tweezers: A Bimolecular Complex with Kinetic Stability}, volume = 52, year = 2013 }

  %0 Journal Article %1 ANIE:ANIE201302479 %A Shao, Changzhun %A Stolte, Matthias %A Würthner, Frank %D 2013 %I WILEY-VCH Verlag %J Angew. Chem. Int. Ed. %N 29 %P 7482--7486 %R 10.1002/anie.201302479 %T Quadruple π Stack of Two Perylene Bisimide Tweezers: A Bimolecular Complex with Kinetic Stability %U http://dx.doi.org/10.1002/anie.201302479 %V 52
• Large room-temperature magnetoresistance in lateral organic spin valves fabricated by in situ shadow evaporation. Grünewald, M.; Kleinlein, J.; Syrowatka, F.; Würthner, F.; Molenkamp, L.W.; Schmidt, G. In Organic Electronics, 14(8), pp. 2082–2086. 2013.
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  Abstract We report the successful fabrication of lateral organic spin valves with a channel length in the sub 100nm regime. The fabrication process is based on in situ shadow evaporation under UHV conditions and therefore yields clean and oxygen-free interfaces between the ferromagnetic metallic electrodes and the organic semiconductor. The spin valve devices consist of Nickel and Cobalt–Iron electrodes and the high mobility n-type organic semiconductor N,N′-bis(heptafluorobutyl)-3,4:9,10-perylene diimide. Our studies comprise fundamental investigations of the process’ and materials’ suitability for the fabrication of lateral spin valve devices as well as magnetotransport measurements at room temperature. The best devices exhibit a magnetoresistance of up to 50%, the largest value for room temperature reported so far.

  @article{GRUNEWALD20132082, abstract = {Abstract We report the successful fabrication of lateral organic spin valves with a channel length in the sub 100nm regime. The fabrication process is based on in situ shadow evaporation under UHV conditions and therefore yields clean and oxygen-free interfaces between the ferromagnetic metallic electrodes and the organic semiconductor. The spin valve devices consist of Nickel and Cobalt–Iron electrodes and the high mobility n-type organic semiconductor N,N′-bis(heptafluorobutyl)-3,4:9,10-perylene diimide. Our studies comprise fundamental investigations of the process’ and materials’ suitability for the fabrication of lateral spin valve devices as well as magnetotransport measurements at room temperature. The best devices exhibit a magnetoresistance of up to 50%, the largest value for room temperature reported so far.}, author = {Grünewald, M. and Kleinlein, J. and Syrowatka, F. and Würthner, F. and Molenkamp, L.W. and Schmidt, G.}, journal = {Organic Electronics}, keywords = {temperature}, number = 8, pages = {2082 - 2086}, title = {Large room-temperature magnetoresistance in lateral organic spin valves fabricated by in situ shadow evaporation}, volume = 14, year = 2013 }

  %0 Journal Article %1 GRUNEWALD20132082 %A Grünewald, M. %A Kleinlein, J. %A Syrowatka, F. %A Würthner, F. %A Molenkamp, L.W. %A Schmidt, G. %D 2013 %J Organic Electronics %N 8 %P 2082 - 2086 %R https://doi.org/10.1016/j.orgel.2013.04.049 %T Large room-temperature magnetoresistance in lateral organic spin valves fabricated by in situ shadow evaporation %U http://www.sciencedirect.com/science/article/pii/S156611991300219X %V 14 %X Abstract We report the successful fabrication of lateral organic spin valves with a channel length in the sub 100nm regime. The fabrication process is based on in situ shadow evaporation under UHV conditions and therefore yields clean and oxygen-free interfaces between the ferromagnetic metallic electrodes and the organic semiconductor. The spin valve devices consist of Nickel and Cobalt–Iron electrodes and the high mobility n-type organic semiconductor N,N′-bis(heptafluorobutyl)-3,4:9,10-perylene diimide. Our studies comprise fundamental investigations of the process’ and materials’ suitability for the fabrication of lateral spin valve devices as well as magnetotransport measurements at room temperature. The best devices exhibit a magnetoresistance of up to 50%, the largest value for room temperature reported so far.
• Similarities and Differences in the Optical Response of Perylene-Based Hetero-Bichromophores and Their Monomeric Units. Selig, Ulrike; Nuernberger, Patrick; Dehm, Volker; Settels, Volker; Gsänger, Marcel; Engels, Bernd; Würthner, Frank; Brixner, Tobias. In ChemPhysChem, 14(7), pp. 1413–1422. 2013.
  • [ Abstract ]
  • [ BibTeX ]
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  The linear and nonlinear optical response of molecular hetero-dimers and their composing perylene units is explored with fluorometry, steady-state and transient absorption, and coherent two-dimensional electronic spectroscopy. Supported by a Förster theory approach and ab initio calculations, we disclose the photoinduced dynamics comprising excitonic coupling, conformational changes, charge transfer, and relaxation dynamics. The influence of the actual orientation of the two chromophore units on these processes is investigated by employing two bichromophores built of the same monomeric units but linked differently.

  @article{CPHC:CPHC201300062, abstract = {The linear and nonlinear optical response of molecular hetero-dimers and their composing perylene units is explored with fluorometry, steady-state and transient absorption, and coherent two-dimensional electronic spectroscopy. Supported by a Förster theory approach and ab initio calculations, we disclose the photoinduced dynamics comprising excitonic coupling, conformational changes, charge transfer, and relaxation dynamics. The influence of the actual orientation of the two chromophore units on these processes is investigated by employing two bichromophores built of the same monomeric units but linked differently.}, author = {Selig, Ulrike and Nuernberger, Patrick and Dehm, Volker and Settels, Volker and Gsänger, Marcel and Engels, Bernd and Würthner, Frank and Brixner, Tobias}, journal = {ChemPhysChem}, keywords = {myown}, number = 7, pages = {1413–1422}, publisher = {WILEY-VCH Verlag}, title = {Similarities and Differences in the Optical Response of Perylene-Based Hetero-Bichromophores and Their Monomeric Units}, volume = 14, year = 2013 }

  %0 Journal Article %1 CPHC:CPHC201300062 %A Selig, Ulrike %A Nuernberger, Patrick %A Dehm, Volker %A Settels, Volker %A Gsänger, Marcel %A Engels, Bernd %A Würthner, Frank %A Brixner, Tobias %D 2013 %I WILEY-VCH Verlag %J ChemPhysChem %N 7 %P 1413--1422 %R 10.1002/cphc.201300062 %T Similarities and Differences in the Optical Response of Perylene-Based Hetero-Bichromophores and Their Monomeric Units %U http://dx.doi.org/10.1002/cphc.201300062 %V 14 %X The linear and nonlinear optical response of molecular hetero-dimers and their composing perylene units is explored with fluorometry, steady-state and transient absorption, and coherent two-dimensional electronic spectroscopy. Supported by a Förster theory approach and ab initio calculations, we disclose the photoinduced dynamics comprising excitonic coupling, conformational changes, charge transfer, and relaxation dynamics. The influence of the actual orientation of the two chromophore units on these processes is investigated by employing two bichromophores built of the same monomeric units but linked differently.
• Evidence for Kinetic Nucleation in Helical Nanofiber Formation Directed by Chiral Solvent for a Perylene Bisimide Organogelator. Stepanenko, Vladimir; Li, Xue-Qing; Gershberg, Jana; Würthner, Frank. In Chemistry – A European Journal, 19(13), pp. 4176–4183. 2013.
  • [ Abstract ]
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  The self-assembly behavior of an achiral perylene bisimide (PBI) organogelator that bears two 3,4,5-tridodecyloxybenzoylaminoethyl substituents at the imide positions has been investigated in chiral solvents (R)- and (S)-limonene in great detail by circular dichroism (CD) spectroscopy and atomic force microscopy (AFM). CD spectroscopic studies on dilute solutions revealed a preferential population of one-handed helical assemblies in chiral solvent with an enantiomeric excess close to 100 %, whereas AFM images of more than 100 nanofibers of the organogel obtained from more concentrated solutions were found to consist of both handed helices with an enantiomeric excess of only 20 %. This discrepancy is attributed to the fast gelation process at high dye concentration that evidently proceeds through non-equilibrated nuclei in a kinetic rather than thermodynamic self-assembly process. Under these conditions the chiral induction from the homochiral solvent may not be adequate in effectively populating only one-handed helices.

  @article{CHEM:CHEM201204146, abstract = {The self-assembly behavior of an achiral perylene bisimide (PBI) organogelator that bears two 3,4,5-tridodecyloxybenzoylaminoethyl substituents at the imide positions has been investigated in chiral solvents (R)- and (S)-limonene in great detail by circular dichroism (CD) spectroscopy and atomic force microscopy (AFM). CD spectroscopic studies on dilute solutions revealed a preferential population of one-handed helical assemblies in chiral solvent with an enantiomeric excess close to 100 %, whereas AFM images of more than 100 nanofibers of the organogel obtained from more concentrated solutions were found to consist of both handed helices with an enantiomeric excess of only 20 %. This discrepancy is attributed to the fast gelation process at high dye concentration that evidently proceeds through non-equilibrated nuclei in a kinetic rather than thermodynamic self-assembly process. Under these conditions the chiral induction from the homochiral solvent may not be adequate in effectively populating only one-handed helices.}, author = {Stepanenko, Vladimir and Li, Xue-Qing and Gershberg, Jana and Würthner, Frank}, journal = {Chemistry – A European Journal}, keywords = {myown}, number = 13, pages = {4176–4183}, publisher = {WILEY-VCH Verlag}, title = {Evidence for Kinetic Nucleation in Helical Nanofiber Formation Directed by Chiral Solvent for a Perylene Bisimide Organogelator}, volume = 19, year = 2013 }

  %0 Journal Article %1 CHEM:CHEM201204146 %A Stepanenko, Vladimir %A Li, Xue-Qing %A Gershberg, Jana %A Würthner, Frank %D 2013 %I WILEY-VCH Verlag %J Chemistry – A European Journal %N 13 %P 4176--4183 %R 10.1002/chem.201204146 %T Evidence for Kinetic Nucleation in Helical Nanofiber Formation Directed by Chiral Solvent for a Perylene Bisimide Organogelator %U http://dx.doi.org/10.1002/chem.201204146 %V 19 %X The self-assembly behavior of an achiral perylene bisimide (PBI) organogelator that bears two 3,4,5-tridodecyloxybenzoylaminoethyl substituents at the imide positions has been investigated in chiral solvents (R)- and (S)-limonene in great detail by circular dichroism (CD) spectroscopy and atomic force microscopy (AFM). CD spectroscopic studies on dilute solutions revealed a preferential population of one-handed helical assemblies in chiral solvent with an enantiomeric excess close to 100 %, whereas AFM images of more than 100 nanofibers of the organogel obtained from more concentrated solutions were found to consist of both handed helices with an enantiomeric excess of only 20 %. This discrepancy is attributed to the fast gelation process at high dye concentration that evidently proceeds through non-equilibrated nuclei in a kinetic rather than thermodynamic self-assembly process. Under these conditions the chiral induction from the homochiral solvent may not be adequate in effectively populating only one-handed helices.
• Synthesis and Molecular Properties of Acceptor-Substituted Squaraine Dyes. Mayerhöffer, Ulrich; Gsänger, Marcel; Stolte, Matthias; Fimmel, Benjamin; Würthner, Frank. In Chemistry – A European Journal, 19(1), pp. 218–232. 2013.
  • [ Abstract ]
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  A broad series of more than 20 acceptor-substituted squaraines was synthesized that feature different acceptor functionalities at the central squaraine four-membered ring. The influence of these acceptor units on the reactivity of semisquaraine precursors and stability of the respective squaraines were explored. Thereby the dicyanovinyl group was found to be the most versatile acceptor group that enabled various modifications at the donor moiety of the squaraine scaffold, leading to an extended series of dicyanovinyl-functionalized squaraines. The variation of donor units afforded a set of NIR fluorophores that cover a wavelength region from the visible at about 650 nm far into the NIR up to 920 nm with fluorescence quantum yields between 0.93 and 0.11 and outstanding optical brightness. This excellent optical property is related to a rigid molecular scaffold that is fixed in an all-cis configuration by the additional dicyanovinyl acceptor unit. The change of the molecular symmetry from C2h to C2v upon functionalization of the squaraine core with dicyanovinyl acceptor group has been confirmed in solution by electro-optical absorption (EOA) spectroscopy, revealing permanent ground-state dipole moments μg in the range between 4.3 and 6.4 D. These dipole moments direct an antiparallel packing of the molecules in the solid state according to single-crystal X-ray analyses achieved for four dicyanovinyl-functionalized squaraines. The structural properties, the EOA results, as well as the band shapes of the optical spectra indicate that these polymethine dyes are cyanine-type chromophores. It is worth noting that the orientation of the dipole moment vectors is orthogonal to the orientation of the transition dipole moment vectors, which is an uncommon but characteristic feature of this rather novel class of polymethine dyes. With regard to applications of these dyes in organic solar cells, their redox properties were also studied by cyclic voltammetry.

  @article{CHEM:CHEM201202783, abstract = {A broad series of more than 20 acceptor-substituted squaraines was synthesized that feature different acceptor functionalities at the central squaraine four-membered ring. The influence of these acceptor units on the reactivity of semisquaraine precursors and stability of the respective squaraines were explored. Thereby the dicyanovinyl group was found to be the most versatile acceptor group that enabled various modifications at the donor moiety of the squaraine scaffold, leading to an extended series of dicyanovinyl-functionalized squaraines. The variation of donor units afforded a set of NIR fluorophores that cover a wavelength region from the visible at about 650 nm far into the NIR up to 920 nm with fluorescence quantum yields between 0.93 and 0.11 and outstanding optical brightness. This excellent optical property is related to a rigid molecular scaffold that is fixed in an all-cis configuration by the additional dicyanovinyl acceptor unit. The change of the molecular symmetry from C2h to C2v upon functionalization of the squaraine core with dicyanovinyl acceptor group has been confirmed in solution by electro-optical absorption (EOA) spectroscopy, revealing permanent ground-state dipole moments μg in the range between 4.3 and 6.4 D. These dipole moments direct an antiparallel packing of the molecules in the solid state according to single-crystal X-ray analyses achieved for four dicyanovinyl-functionalized squaraines. The structural properties, the EOA results, as well as the band shapes of the optical spectra indicate that these polymethine dyes are cyanine-type chromophores. It is worth noting that the orientation of the dipole moment vectors is orthogonal to the orientation of the transition dipole moment vectors, which is an uncommon but characteristic feature of this rather novel class of polymethine dyes. With regard to applications of these dyes in organic solar cells, their redox properties were also studied by cyclic voltammetry.}, author = {Mayerhöffer, Ulrich and Gsänger, Marcel and Stolte, Matthias and Fimmel, Benjamin and Würthner, Frank}, journal = {Chemistry – A European Journal}, keywords = {myown}, number = 1, pages = {218–232}, publisher = {WILEY-VCH Verlag}, title = {Synthesis and Molecular Properties of Acceptor-Substituted Squaraine Dyes}, volume = 19, year = 2013 }

  %0 Journal Article %1 CHEM:CHEM201202783 %A Mayerhöffer, Ulrich %A Gsänger, Marcel %A Stolte, Matthias %A Fimmel, Benjamin %A Würthner, Frank %D 2013 %I WILEY-VCH Verlag %J Chemistry – A European Journal %N 1 %P 218--232 %R 10.1002/chem.201202783 %T Synthesis and Molecular Properties of Acceptor-Substituted Squaraine Dyes %U http://dx.doi.org/10.1002/chem.201202783 %V 19 %X A broad series of more than 20 acceptor-substituted squaraines was synthesized that feature different acceptor functionalities at the central squaraine four-membered ring. The influence of these acceptor units on the reactivity of semisquaraine precursors and stability of the respective squaraines were explored. Thereby the dicyanovinyl group was found to be the most versatile acceptor group that enabled various modifications at the donor moiety of the squaraine scaffold, leading to an extended series of dicyanovinyl-functionalized squaraines. The variation of donor units afforded a set of NIR fluorophores that cover a wavelength region from the visible at about 650 nm far into the NIR up to 920 nm with fluorescence quantum yields between 0.93 and 0.11 and outstanding optical brightness. This excellent optical property is related to a rigid molecular scaffold that is fixed in an all-cis configuration by the additional dicyanovinyl acceptor unit. The change of the molecular symmetry from C2h to C2v upon functionalization of the squaraine core with dicyanovinyl acceptor group has been confirmed in solution by electro-optical absorption (EOA) spectroscopy, revealing permanent ground-state dipole moments μg in the range between 4.3 and 6.4 D. These dipole moments direct an antiparallel packing of the molecules in the solid state according to single-crystal X-ray analyses achieved for four dicyanovinyl-functionalized squaraines. The structural properties, the EOA results, as well as the band shapes of the optical spectra indicate that these polymethine dyes are cyanine-type chromophores. It is worth noting that the orientation of the dipole moment vectors is orthogonal to the orientation of the transition dipole moment vectors, which is an uncommon but characteristic feature of this rather novel class of polymethine dyes. With regard to applications of these dyes in organic solar cells, their redox properties were also studied by cyclic voltammetry.
• Synthesis of a Non-aggregating Bay-Unsubstituted Perylene Bisimide Dye with Latent Bromo Groups for C–C Cross Coupling. Frischmann, Peter D.; Würthner, Frank. In Organic Letters, 15(18), pp. 4674–4677. 2013.

  PMID: 24015879
  • [ Abstract ]
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  To address the absence of synthetic routes to access easily functionalizable, non-aggregating, and soluble bay-unsubstituted perylene bisimide dyes, an efficient, three-step, multigram-scale synthesis of the divergent building block N,N′-bis(4-bromo-2,6-diisopropylphenyl)perylene-3,4:9,10-tetracarboxylic bisimide is reported. Suzuki coupling yields new dyes that maintain excellent solubility and exhibit unity quantum yields in CHCl3, THF, toluene, and CH3CN. The methodology reported here enables access to dyes with sensitive functional groups such as aldehydes that are not accessible by traditional imidization routes.

  @article{doi:10.1021/ol401946g, abstract = {To address the absence of synthetic routes to access easily functionalizable, non-aggregating, and soluble bay-unsubstituted perylene bisimide dyes, an efficient, three-step, multigram-scale synthesis of the divergent building block N,N′-bis(4-bromo-2,6-diisopropylphenyl)perylene-3,4:9,10-tetracarboxylic bisimide is reported. Suzuki coupling yields new dyes that maintain excellent solubility and exhibit unity quantum yields in CHCl3, THF, toluene, and CH3CN. The methodology reported here enables access to dyes with sensitive functional groups such as aldehydes that are not accessible by traditional imidization routes.}, author = {Frischmann, Peter D. and Würthner, Frank}, journal = {Organic Letters}, keywords = {myown}, note = {PMID: 24015879}, number = 18, pages = {4674-4677}, title = {Synthesis of a Non-aggregating Bay-Unsubstituted Perylene Bisimide Dye with Latent Bromo Groups for C–C Cross Coupling}, volume = 15, year = 2013 }

  %0 Journal Article %1 doi:10.1021/ol401946g %A Frischmann, Peter D. %A Würthner, Frank %D 2013 %J Organic Letters %N 18 %P 4674-4677 %R 10.1021/ol401946g %T Synthesis of a Non-aggregating Bay-Unsubstituted Perylene Bisimide Dye with Latent Bromo Groups for C–C Cross Coupling %U http://dx.doi.org/10.1021/ol401946g %V 15 %X To address the absence of synthetic routes to access easily functionalizable, non-aggregating, and soluble bay-unsubstituted perylene bisimide dyes, an efficient, three-step, multigram-scale synthesis of the divergent building block N,N′-bis(4-bromo-2,6-diisopropylphenyl)perylene-3,4:9,10-tetracarboxylic bisimide is reported. Suzuki coupling yields new dyes that maintain excellent solubility and exhibit unity quantum yields in CHCl3, THF, toluene, and CH3CN. The methodology reported here enables access to dyes with sensitive functional groups such as aldehydes that are not accessible by traditional imidization routes.
• Ultrafast Exciton Self-Trapping upon Geometry Deformation in Perylene-Based Molecular Aggregates. Schubert, Alexander; Settels, Volker; Liu, Wenlan; Würthner, Frank; Meier, Christoph; Fink, Reinhold F.; Schindlbeck, Stefan; Lochbrunner, Stefan; Engels, Bernd; Engel, Volker. In J. Phys. Chem. Lett., 4(5), pp. 792–796. 2013.

  PMID: 26281934
  • [ Abstract ]
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  Femtosecond time-resolved experiments demonstrate that the photoexcited state of perylene tetracarboxylic acid bisimide (PBI) aggregates in solution decays nonradiatively on a time-scale of 215 fs. High-level electronic structure calculations on dimers point toward the importance of an excited state intermolecular geometry distortion along a reaction coordinate that induces energy shifts and couplings between various electronic states. Time-dependent wave packet calculations incorporating a simple dissipation mechanism indicate that the fast energy quenching results from a doorway state with a charge-transfer character that is only transiently populated. The identified relaxation mechanism corresponds to a possible exciton trap in molecular materials.

  @article{doi:10.1021/jz4000752, abstract = {Femtosecond time-resolved experiments demonstrate that the photoexcited state of perylene tetracarboxylic acid bisimide (PBI) aggregates in solution decays nonradiatively on a time-scale of 215 fs. High-level electronic structure calculations on dimers point toward the importance of an excited state intermolecular geometry distortion along a reaction coordinate that induces energy shifts and couplings between various electronic states. Time-dependent wave packet calculations incorporating a simple dissipation mechanism indicate that the fast energy quenching results from a doorway state with a charge-transfer character that is only transiently populated. The identified relaxation mechanism corresponds to a possible exciton trap in molecular materials.}, author = {Schubert, Alexander and Settels, Volker and Liu, Wenlan and Würthner, Frank and Meier, Christoph and Fink, Reinhold F. and Schindlbeck, Stefan and Lochbrunner, Stefan and Engels, Bernd and Engel, Volker}, journal = {J. Phys. Chem. Lett.}, keywords = {myown}, note = {PMID: 26281934}, number = 5, pages = {792-796}, title = {Ultrafast Exciton Self-Trapping upon Geometry Deformation in Perylene-Based Molecular Aggregates}, volume = 4, year = 2013 }

  %0 Journal Article %1 doi:10.1021/jz4000752 %A Schubert, Alexander %A Settels, Volker %A Liu, Wenlan %A Würthner, Frank %A Meier, Christoph %A Fink, Reinhold F. %A Schindlbeck, Stefan %A Lochbrunner, Stefan %A Engels, Bernd %A Engel, Volker %D 2013 %J J. Phys. Chem. Lett. %N 5 %P 792-796 %R 10.1021/jz4000752 %T Ultrafast Exciton Self-Trapping upon Geometry Deformation in Perylene-Based Molecular Aggregates %U http://dx.doi.org/10.1021/jz4000752 %V 4 %X Femtosecond time-resolved experiments demonstrate that the photoexcited state of perylene tetracarboxylic acid bisimide (PBI) aggregates in solution decays nonradiatively on a time-scale of 215 fs. High-level electronic structure calculations on dimers point toward the importance of an excited state intermolecular geometry distortion along a reaction coordinate that induces energy shifts and couplings between various electronic states. Time-dependent wave packet calculations incorporating a simple dissipation mechanism indicate that the fast energy quenching results from a doorway state with a charge-transfer character that is only transiently populated. The identified relaxation mechanism corresponds to a possible exciton trap in molecular materials.
• Core-Brominated Tetraazaperopyrenes as n-Channel Semiconductors for Organic Complementary Circuits on Flexible Substrates. Geib, Sonja; Zschieschang, Ute; Gsänger, Marcel; Stolte, Matthias; Würthner, Frank; Wadepohl, Hubert; Klauk, Hagen; Gade, Lutz H. In Advanced Functional Materials, 23(31), pp. 3866–3874. 2013.
  • [ Abstract ]
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  Organic thin-film transistors (TFTs) are prepared by vacuum deposition and solution shearing of 2,9-bis(perfluoroalkyl)-substituted tetraazaperopyrenes (TAPPs) with bromine substituents at the aromatic core. The TAPP derivatives are synthesized by reacting known unsubstituted TAPPs with bromine in fuming sulphuric acid, and their electrochemical properties are studied in detail by cyclic voltammetry and modelled with density functional theory (DFT) methods. Lowest unoccupied molecular orbital (LUMO) energies and electron affinities indicate that the core-brominated TAPPs should exhibit n-channel semiconducting properties. Current-voltage characteristics of the TFTs established electron mobilities of up to μn = 0.032 cm2 V−1 s−1 for a derivative which was subsequently processed in the fabrication of a complementary ring oscillator on a flexible plastic substrate (PEN).

  @article{ADFM:ADFM201203600, abstract = {Organic thin-film transistors (TFTs) are prepared by vacuum deposition and solution shearing of 2,9-bis(perfluoroalkyl)-substituted tetraazaperopyrenes (TAPPs) with bromine substituents at the aromatic core. The TAPP derivatives are synthesized by reacting known unsubstituted TAPPs with bromine in fuming sulphuric acid, and their electrochemical properties are studied in detail by cyclic voltammetry and modelled with density functional theory (DFT) methods. Lowest unoccupied molecular orbital (LUMO) energies and electron affinities indicate that the core-brominated TAPPs should exhibit n-channel semiconducting properties. Current-voltage characteristics of the TFTs established electron mobilities of up to μn = 0.032 cm2 V−1 s−1 for a derivative which was subsequently processed in the fabrication of a complementary ring oscillator on a flexible plastic substrate (PEN).}, author = {Geib, Sonja and Zschieschang, Ute and Gsänger, Marcel and Stolte, Matthias and Würthner, Frank and Wadepohl, Hubert and Klauk, Hagen and Gade, Lutz H.}, journal = {Advanced Functional Materials}, keywords = {myown}, number = 31, pages = {3866–3874}, publisher = {WILEY-VCH Verlag}, title = {Core-Brominated Tetraazaperopyrenes as n-Channel Semiconductors for Organic Complementary Circuits on Flexible Substrates}, volume = 23, year = 2013 }

  %0 Journal Article %1 ADFM:ADFM201203600 %A Geib, Sonja %A Zschieschang, Ute %A Gsänger, Marcel %A Stolte, Matthias %A Würthner, Frank %A Wadepohl, Hubert %A Klauk, Hagen %A Gade, Lutz H. %D 2013 %I WILEY-VCH Verlag %J Advanced Functional Materials %N 31 %P 3866--3874 %R 10.1002/adfm.201203600 %T Core-Brominated Tetraazaperopyrenes as n-Channel Semiconductors for Organic Complementary Circuits on Flexible Substrates %U http://dx.doi.org/10.1002/adfm.201203600 %V 23 %X Organic thin-film transistors (TFTs) are prepared by vacuum deposition and solution shearing of 2,9-bis(perfluoroalkyl)-substituted tetraazaperopyrenes (TAPPs) with bromine substituents at the aromatic core. The TAPP derivatives are synthesized by reacting known unsubstituted TAPPs with bromine in fuming sulphuric acid, and their electrochemical properties are studied in detail by cyclic voltammetry and modelled with density functional theory (DFT) methods. Lowest unoccupied molecular orbital (LUMO) energies and electron affinities indicate that the core-brominated TAPPs should exhibit n-channel semiconducting properties. Current-voltage characteristics of the TFTs established electron mobilities of up to μn = 0.032 cm2 V−1 s−1 for a derivative which was subsequently processed in the fabrication of a complementary ring oscillator on a flexible plastic substrate (PEN).
• Structure–Property Relationship of Perylene Bisimide Macrocycles Probed by Atomic Force Microscopy and Single-Molecule Fluorescence Spectroscopy. Lee, Ji-Eun; Stepanenko, Vladimir; Yang, Jaesung; Yoo, Hyejin; Schlosser, Felix; Bellinger, Daniel; Engels, Bernd; Scheblykin, Ivan G.; Würthner, Frank; Kim, Dongho. In ACS Nano, 7(6), pp. 5064–5076. 2013.

  PMID: 23656366
  • [ Abstract ]
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  Properties of a series of acetylene-linked perylene bisimide (PBI) macrocycles with different ring size composed of three to six PBI dyes were investigated by atomic force microscopy (AFM) and single-molecule fluorescence spectroscopy in a condensed phase. It was demonstrated that the structures of PBI cyclic arrays (CNs, N = 3, 4, 5, and 6) become distorted with increasing the ring size through molecular dynamics (MD) simulations (PM6-DH2 method) and AFM height images of CNs on highly ordered pyrolytic graphite (HOPG) surface. The MD simulations showed that only C5 and C6 rings are highly flexible molecules whose planarization goes along with a significant energetic penalty. Accordingly, both molecules did not show ordered adlayers on a HOPG surface. In contrast, C3 and C4 are far more rigid molecules leading to well-ordered hexagonal (C3) and rectangular (C4) 2D lattices. At the single-molecule level, we showed that the fluorescence properties of single CNs are affected by the structural changes. The fluorescence lifetimes of CNs became shorter and their distributions became broader due to the structural distortions with increasing the ring size. Furthermore, the CNs of smaller ring size exhibit a higher photostability and an efficient excitation energy transfer (EET) due to the more well-defined and planar structures compared to the larger CNs. Consequently, these observations provide evidence that not only PBI macrocycles are promising candidates for artificial light-harvesting systems, but also the photophysical properties of CNs are strongly related to the structural rigidity of CNs.

  @article{doi:10.1021/nn400616u, abstract = {Properties of a series of acetylene-linked perylene bisimide (PBI) macrocycles with different ring size composed of three to six PBI dyes were investigated by atomic force microscopy (AFM) and single-molecule fluorescence spectroscopy in a condensed phase. It was demonstrated that the structures of PBI cyclic arrays (CNs, N = 3, 4, 5, and 6) become distorted with increasing the ring size through molecular dynamics (MD) simulations (PM6-DH2 method) and AFM height images of CNs on highly ordered pyrolytic graphite (HOPG) surface. The MD simulations showed that only C5 and C6 rings are highly flexible molecules whose planarization goes along with a significant energetic penalty. Accordingly, both molecules did not show ordered adlayers on a HOPG surface. In contrast, C3 and C4 are far more rigid molecules leading to well-ordered hexagonal (C3) and rectangular (C4) 2D lattices. At the single-molecule level, we showed that the fluorescence properties of single CNs are affected by the structural changes. The fluorescence lifetimes of CNs became shorter and their distributions became broader due to the structural distortions with increasing the ring size. Furthermore, the CNs of smaller ring size exhibit a higher photostability and an efficient excitation energy transfer (EET) due to the more well-defined and planar structures compared to the larger CNs. Consequently, these observations provide evidence that not only PBI macrocycles are promising candidates for artificial light-harvesting systems, but also the photophysical properties of CNs are strongly related to the structural rigidity of CNs.}, author = {Lee, Ji-Eun and Stepanenko, Vladimir and Yang, Jaesung and Yoo, Hyejin and Schlosser, Felix and Bellinger, Daniel and Engels, Bernd and Scheblykin, Ivan G. and Würthner, Frank and Kim, Dongho}, journal = {ACS Nano}, keywords = {myown}, note = {PMID: 23656366}, number = 6, pages = {5064-5076}, title = {Structure–Property Relationship of Perylene Bisimide Macrocycles Probed by Atomic Force Microscopy and Single-Molecule Fluorescence Spectroscopy}, volume = 7, year = 2013 }

  %0 Journal Article %1 doi:10.1021/nn400616u %A Lee, Ji-Eun %A Stepanenko, Vladimir %A Yang, Jaesung %A Yoo, Hyejin %A Schlosser, Felix %A Bellinger, Daniel %A Engels, Bernd %A Scheblykin, Ivan G. %A Würthner, Frank %A Kim, Dongho %D 2013 %J ACS Nano %N 6 %P 5064-5076 %R 10.1021/nn400616u %T Structure–Property Relationship of Perylene Bisimide Macrocycles Probed by Atomic Force Microscopy and Single-Molecule Fluorescence Spectroscopy %U http://dx.doi.org/10.1021/nn400616u %V 7 %X Properties of a series of acetylene-linked perylene bisimide (PBI) macrocycles with different ring size composed of three to six PBI dyes were investigated by atomic force microscopy (AFM) and single-molecule fluorescence spectroscopy in a condensed phase. It was demonstrated that the structures of PBI cyclic arrays (CNs, N = 3, 4, 5, and 6) become distorted with increasing the ring size through molecular dynamics (MD) simulations (PM6-DH2 method) and AFM height images of CNs on highly ordered pyrolytic graphite (HOPG) surface. The MD simulations showed that only C5 and C6 rings are highly flexible molecules whose planarization goes along with a significant energetic penalty. Accordingly, both molecules did not show ordered adlayers on a HOPG surface. In contrast, C3 and C4 are far more rigid molecules leading to well-ordered hexagonal (C3) and rectangular (C4) 2D lattices. At the single-molecule level, we showed that the fluorescence properties of single CNs are affected by the structural changes. The fluorescence lifetimes of CNs became shorter and their distributions became broader due to the structural distortions with increasing the ring size. Furthermore, the CNs of smaller ring size exhibit a higher photostability and an efficient excitation energy transfer (EET) due to the more well-defined and planar structures compared to the larger CNs. Consequently, these observations provide evidence that not only PBI macrocycles are promising candidates for artificial light-harvesting systems, but also the photophysical properties of CNs are strongly related to the structural rigidity of CNs.
• Enhanced photocurrent generation by folding-driven H-aggregate formation. Zitzler-Kunkel, Andre; Lenze, Martin R.; Meerholz, Klaus; Würthner, Frank. In Chem. Sci., 4(5), pp. 2071–2075. 2013.
  • [ Abstract ]
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  A novel bis(merocyanine) dye has been synthesized and its folding and aggregation behavior has been elucidated in dependence on the solvent polarity. Extended cofacially [small pi]-stacked H-aggregates could be prepared in nonpolar solvents based on the preorganized folded dimer structure of the dye exhibiting a more than 120 nm hypsochromic shift of the absorption band. Furthermore, incorporation of such H-aggregate domains in bulk heterojunction (BHJ) solar cells by careful adjustment of processing conditions afforded a nearly twofold increase in the photocurrent generation. Our detailed investigations on the external quantum efficiencies of these blends reveal that the increase of the short-circuit current density JSC stems from the H-aggregated dye manifold in the photoactive layer of the solar cell devices.

  @article{C3SC50263E, abstract = {A novel bis(merocyanine) dye has been synthesized and its folding and aggregation behavior has been elucidated in dependence on the solvent polarity. Extended cofacially [small pi]-stacked H-aggregates could be prepared in nonpolar solvents based on the preorganized folded dimer structure of the dye exhibiting a more than 120 nm hypsochromic shift of the absorption band. Furthermore{,} incorporation of such H-aggregate domains in bulk heterojunction (BHJ) solar cells by careful adjustment of processing conditions afforded a nearly twofold increase in the photocurrent generation. Our detailed investigations on the external quantum efficiencies of these blends reveal that the increase of the short-circuit current density JSC stems from the H-aggregated dye manifold in the photoactive layer of the solar cell devices.}, author = {Zitzler-Kunkel, Andre and Lenze, Martin R. and Meerholz, Klaus and Würthner, Frank}, journal = {Chem. Sci.}, keywords = {myown}, number = 5, pages = {2071-2075}, publisher = {The Royal Society of Chemistry}, title = {Enhanced photocurrent generation by folding-driven H-aggregate formation}, volume = 4, year = 2013 }

  %0 Journal Article %1 C3SC50263E %A Zitzler-Kunkel, Andre %A Lenze, Martin R. %A Meerholz, Klaus %A Würthner, Frank %D 2013 %I The Royal Society of Chemistry %J Chem. Sci. %N 5 %P 2071-2075 %R 10.1039/C3SC50263E %T Enhanced photocurrent generation by folding-driven H-aggregate formation %U http://dx.doi.org/10.1039/C3SC50263E %V 4 %X A novel bis(merocyanine) dye has been synthesized and its folding and aggregation behavior has been elucidated in dependence on the solvent polarity. Extended cofacially [small pi]-stacked H-aggregates could be prepared in nonpolar solvents based on the preorganized folded dimer structure of the dye exhibiting a more than 120 nm hypsochromic shift of the absorption band. Furthermore, incorporation of such H-aggregate domains in bulk heterojunction (BHJ) solar cells by careful adjustment of processing conditions afforded a nearly twofold increase in the photocurrent generation. Our detailed investigations on the external quantum efficiencies of these blends reveal that the increase of the short-circuit current density JSC stems from the H-aggregated dye manifold in the photoactive layer of the solar cell devices.
• Exciton delocalization and dynamics in helical [small pi]-stacks of self-assembled perylene bisimides. Lim, Jong Min; Kim, Pyosang; Yoon, Min-Chul; Sung, Jooyoung; Dehm, Volker; Chen, Zhijian; Würthner, Frank; Kim, Dongho. In Chem. Sci., 4(1), pp. 388–397. 2013.
  • [ Abstract ]
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  Whilst the excitonic properties of J-aggregates have been investigated in great detail, those of H-aggregates have not been systematically investigated yet. In this regard, we have explored the exciton dynamics and excited-species formation processes in columnar H-aggregates of planar PBI dyes that are stacked in a helical fashion by various spectroscopic techniques such as time correlated single-photon counting and femtosecond pump-probe measurements with anisotropy changes. The outcome of this study is that photogenerated excitons in helically stacked PBI dyes experience complicated relaxation processes that involve excited-state interactions such as exciton delocalization and excimer formation. To scrutinize the exciton dynamics in the helically stacked aggregates, we have also included distorted bay-substituted PBI dyes as reference molecules that exhibit either no or only relatively small-sized dimeric aggregate structures. The comparative study revealed that the excited-state interactions in the large-sized helically stacked aggregates extend beyond two PBI units, leading to a final excimer (here, excimer means not only an "excited dimer" but an "excited multimer") trap state within [similar]50 ps. Although in competition with this relaxation path into the excimeric trap state, exciton diffusion has been revealed by exciton-exciton annihilation processes, occurring at high excitation power. Whilst the excimer formation process interrupts the direct observation of exciton diffusion in these columnar PBI aggregates, the exciton migration distance could be estimated by the incorporation of non-fluorescent PBI quencher molecules. From this analysis we can conclude that the exciton diffusion can reach a length of about 10 monomer units. Although this value appears to be shorter than those values observed for J-aggregates, this result shows that columnar PBI stacks might still be useful for optoelectronic applications if the relaxation process leading to excimer traps is prevented, e.g. by structural modifications of the molecules.

  @article{C2SC21178E, abstract = {Whilst the excitonic properties of J-aggregates have been investigated in great detail{,} those of H-aggregates have not been systematically investigated yet. In this regard{,} we have explored the exciton dynamics and excited-species formation processes in columnar H-aggregates of planar PBI dyes that are stacked in a helical fashion by various spectroscopic techniques such as time correlated single-photon counting and femtosecond pump-probe measurements with anisotropy changes. The outcome of this study is that photogenerated excitons in helically stacked PBI dyes experience complicated relaxation processes that involve excited-state interactions such as exciton delocalization and excimer formation. To scrutinize the exciton dynamics in the helically stacked aggregates{,} we have also included distorted bay-substituted PBI dyes as reference molecules that exhibit either no or only relatively small-sized dimeric aggregate structures. The comparative study revealed that the excited-state interactions in the large-sized helically stacked aggregates extend beyond two PBI units{,} leading to a final excimer (here{,} excimer means not only an {"}excited dimer{"} but an {"}excited multimer{"}) trap state within [similar]50 ps. Although in competition with this relaxation path into the excimeric trap state{,} exciton diffusion has been revealed by exciton-exciton annihilation processes{,} occurring at high excitation power. Whilst the excimer formation process interrupts the direct observation of exciton diffusion in these columnar PBI aggregates{,} the exciton migration distance could be estimated by the incorporation of non-fluorescent PBI quencher molecules. From this analysis we can conclude that the exciton diffusion can reach a length of about 10 monomer units. Although this value appears to be shorter than those values observed for J-aggregates{,} this result shows that columnar PBI stacks might still be useful for optoelectronic applications if the relaxation process leading to excimer traps is prevented{,} e.g. by structural modifications of the molecules.}, author = {Lim, Jong Min and Kim, Pyosang and Yoon, Min-Chul and Sung, Jooyoung and Dehm, Volker and Chen, Zhijian and Würthner, Frank and Kim, Dongho}, journal = {Chem. Sci.}, keywords = {myown}, number = 1, pages = {388-397}, publisher = {The Royal Society of Chemistry}, title = {Exciton delocalization and dynamics in helical [small pi]-stacks of self-assembled perylene bisimides}, volume = 4, year = 2013 }

  %0 Journal Article %1 C2SC21178E %A Lim, Jong Min %A Kim, Pyosang %A Yoon, Min-Chul %A Sung, Jooyoung %A Dehm, Volker %A Chen, Zhijian %A Würthner, Frank %A Kim, Dongho %D 2013 %I The Royal Society of Chemistry %J Chem. Sci. %N 1 %P 388-397 %R 10.1039/C2SC21178E %T Exciton delocalization and dynamics in helical [small pi]-stacks of self-assembled perylene bisimides %U http://dx.doi.org/10.1039/C2SC21178E %V 4 %X Whilst the excitonic properties of J-aggregates have been investigated in great detail, those of H-aggregates have not been systematically investigated yet. In this regard, we have explored the exciton dynamics and excited-species formation processes in columnar H-aggregates of planar PBI dyes that are stacked in a helical fashion by various spectroscopic techniques such as time correlated single-photon counting and femtosecond pump-probe measurements with anisotropy changes. The outcome of this study is that photogenerated excitons in helically stacked PBI dyes experience complicated relaxation processes that involve excited-state interactions such as exciton delocalization and excimer formation. To scrutinize the exciton dynamics in the helically stacked aggregates, we have also included distorted bay-substituted PBI dyes as reference molecules that exhibit either no or only relatively small-sized dimeric aggregate structures. The comparative study revealed that the excited-state interactions in the large-sized helically stacked aggregates extend beyond two PBI units, leading to a final excimer (here, excimer means not only an "excited dimer" but an "excited multimer") trap state within [similar]50 ps. Although in competition with this relaxation path into the excimeric trap state, exciton diffusion has been revealed by exciton-exciton annihilation processes, occurring at high excitation power. Whilst the excimer formation process interrupts the direct observation of exciton diffusion in these columnar PBI aggregates, the exciton migration distance could be estimated by the incorporation of non-fluorescent PBI quencher molecules. From this analysis we can conclude that the exciton diffusion can reach a length of about 10 monomer units. Although this value appears to be shorter than those values observed for J-aggregates, this result shows that columnar PBI stacks might still be useful for optoelectronic applications if the relaxation process leading to excimer traps is prevented, e.g. by structural modifications of the molecules.
• Air-Stable n-Channel Organic Single Crystal Field-Effect Transistors Based on Microribbons of Core-Chlorinated Naphthalene Diimide. He, Tao; Stolte, Matthias; Würthner, Frank. In Advanced Materials, 25(48), pp. 6951–6955. 2013.
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  @article{ADMA:ADMA201303392, author = {He, Tao and Stolte, Matthias and Würthner, Frank}, journal = {Advanced Materials}, keywords = {myown}, number = 48, pages = {6951–6955}, title = {Air-Stable n-Channel Organic Single Crystal Field-Effect Transistors Based on Microribbons of Core-Chlorinated Naphthalene Diimide}, volume = 25, year = 2013 }

  %0 Journal Article %1 ADMA:ADMA201303392 %A He, Tao %A Stolte, Matthias %A Würthner, Frank %D 2013 %J Advanced Materials %N 48 %P 6951--6955 %R 10.1002/adma.201303392 %T Air-Stable n-Channel Organic Single Crystal Field-Effect Transistors Based on Microribbons of Core-Chlorinated Naphthalene Diimide %U http://dx.doi.org/10.1002/adma.201303392 %V 25
• Tuning the Redox Properties of Photochromic Diarylethenes by Introducing Electron-Withdrawing Substituents. Berberich, Martin; Würthner, Frank. In Asian Journal of Organic Chemistry, 2(3), pp. 250–256. 2013.
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  A series of seven photochromic diarylethenes (DAEs) with various electron-withdrawing substituents and their respective closed-form isomers (DAEC) were synthesized and the optical and redox properties of these photochromes were investigated by UV/vis absorption spectroscopy and cyclic voltammetry. Our comparative studies with these DAEs revealed that the absorption properties of the closed forms and the redox potentials of the open and closed isomers appreciably depend on the number and nature of the electron-withdrawing groups introduced into the DAE unit. The DAE derivatives can be photochemically switched between two different states with different redox properties. Most prominently, photochrome 3 with two nitro groups has a first reduction potential for the open form 3 o of −1.51 V and for the corresponding closed form 3 c of −0.96 V, and, therefore, is particularly interesting as switchable electron-acceptor moiety in photochromic systems.

  @article{AJOC:AJOC201200179, abstract = {A series of seven photochromic diarylethenes (DAEs) with various electron-withdrawing substituents and their respective closed-form isomers (DAEC) were synthesized and the optical and redox properties of these photochromes were investigated by UV/vis absorption spectroscopy and cyclic voltammetry. Our comparative studies with these DAEs revealed that the absorption properties of the closed forms and the redox potentials of the open and closed isomers appreciably depend on the number and nature of the electron-withdrawing groups introduced into the DAE unit. The DAE derivatives can be photochemically switched between two different states with different redox properties. Most prominently, photochrome 3 with two nitro groups has a first reduction potential for the open form 3 o of −1.51 V and for the corresponding closed form 3 c of −0.96 V, and, therefore, is particularly interesting as switchable electron-acceptor moiety in photochromic systems.}, author = {Berberich, Martin and Würthner, Frank}, journal = {Asian Journal of Organic Chemistry}, keywords = {myown}, number = 3, pages = {250–256}, publisher = {WILEY-VCH Verlag}, title = {Tuning the Redox Properties of Photochromic Diarylethenes by Introducing Electron-Withdrawing Substituents}, volume = 2, year = 2013 }

  %0 Journal Article %1 AJOC:AJOC201200179 %A Berberich, Martin %A Würthner, Frank %D 2013 %I WILEY-VCH Verlag %J Asian Journal of Organic Chemistry %N 3 %P 250--256 %R 10.1002/ajoc.201200179 %T Tuning the Redox Properties of Photochromic Diarylethenes by Introducing Electron-Withdrawing Substituents %U http://dx.doi.org/10.1002/ajoc.201200179 %V 2 %X A series of seven photochromic diarylethenes (DAEs) with various electron-withdrawing substituents and their respective closed-form isomers (DAEC) were synthesized and the optical and redox properties of these photochromes were investigated by UV/vis absorption spectroscopy and cyclic voltammetry. Our comparative studies with these DAEs revealed that the absorption properties of the closed forms and the redox potentials of the open and closed isomers appreciably depend on the number and nature of the electron-withdrawing groups introduced into the DAE unit. The DAE derivatives can be photochemically switched between two different states with different redox properties. Most prominently, photochrome 3 with two nitro groups has a first reduction potential for the open form 3 o of −1.51 V and for the corresponding closed form 3 c of −0.96 V, and, therefore, is particularly interesting as switchable electron-acceptor moiety in photochromic systems.
• Redox-switchable Intramolecular π−π-Stacking of Perylene Bisimide Dyes in a Cyclophane. Schlosser, Felix; Moos, Michael; Lambert, Christoph; Würthner, Frank. In Advanced Materials, 25(3), pp. 410–414. 2013.
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  @article{ADMA:ADMA201201266, author = {Schlosser, Felix and Moos, Michael and Lambert, Christoph and Würthner, Frank}, journal = {Advanced Materials}, keywords = {myown}, number = 3, pages = {410–414}, publisher = {WILEY-VCH Verlag}, title = {Redox-switchable Intramolecular π−π-Stacking of Perylene Bisimide Dyes in a Cyclophane}, volume = 25, year = 2013 }

  %0 Journal Article %1 ADMA:ADMA201201266 %A Schlosser, Felix %A Moos, Michael %A Lambert, Christoph %A Würthner, Frank %D 2013 %I WILEY-VCH Verlag %J Advanced Materials %N 3 %P 410--414 %R 10.1002/adma.201201266 %T Redox-switchable Intramolecular π−π-Stacking of Perylene Bisimide Dyes in a Cyclophane %U http://dx.doi.org/10.1002/adma.201201266 %V 25
• Vertical organic spin valves in perpendicular magnetic fields. Grünewald, M.; Göckeritz, R.; Homonnay, N.; Würthner, F.; Molenkamp, L. W.; Schmidt, G. In Phys. Rev. B, 88(8), p. 085319. 2013.
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  @article{PhysRevB.88.085319, author = {Grünewald, M. and Göckeritz, R. and Homonnay, N. and Würthner, F. and Molenkamp, L. W. and Schmidt, G.}, journal = {Phys. Rev. B}, keywords = {myown}, month = {08}, number = 8, pages = {085319}, publisher = {American Physical Society}, title = {Vertical organic spin valves in perpendicular magnetic fields}, volume = 88, year = 2013 }

  %0 Journal Article %1 PhysRevB.88.085319 %A Grünewald, M. %A Göckeritz, R. %A Homonnay, N. %A Würthner, F. %A Molenkamp, L. W. %A Schmidt, G. %D 2013 %I American Physical Society %J Phys. Rev. B %N 8 %P 085319 %R 10.1103/PhysRevB.88.085319 %T Vertical organic spin valves in perpendicular magnetic fields %U https://link.aps.org/doi/10.1103/PhysRevB.88.085319 %V 88

• Efficient Charge Transport in Semisynthetic Zinc Chlorin Dye Assemblies. Patwardhan, Sameer; Sengupta, Sanchita; Siebbeles, Laurens D. A.; Würthner, Frank; Grozema, Ferdinand C. In J. Am. Chem. Soc., 134(39), pp. 16147–16150. 2012.

  PMID: 22985422
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  We have studied the charge transport properties of self-assembled structures of semisynthetic zinc chlorins (ZnChls) in the solid state by pulsed radiolysis time-resolved microwave conductivity measurements. These materials can form either a two-dimensional (2D) brickwork-type slipped stack arrangement or a one-dimensional (1D) tubular assemblies, depending on the exact molecular structure of the ZnChls. We have observed efficient charge transport with mobilities as high as 0.07 cm2 V–1 s–1 for tubular assemblies of 31-hydroxy ZnChls and up to 0.28 cm2 V–1 s–1 for 2D stacked assemblies of 31-methoxy ZnChls at room temperature. The efficient charge transporting capabilities of these organized assemblies opens the way to supramolecular electronics based on biological systems.

  @article{doi:10.1021/ja3075192, abstract = {We have studied the charge transport properties of self-assembled structures of semisynthetic zinc chlorins (ZnChls) in the solid state by pulsed radiolysis time-resolved microwave conductivity measurements. These materials can form either a two-dimensional (2D) brickwork-type slipped stack arrangement or a one-dimensional (1D) tubular assemblies, depending on the exact molecular structure of the ZnChls. We have observed efficient charge transport with mobilities as high as 0.07 cm2 V–1 s–1 for tubular assemblies of 31-hydroxy ZnChls and up to 0.28 cm2 V–1 s–1 for 2D stacked assemblies of 31-methoxy ZnChls at room temperature. The efficient charge transporting capabilities of these organized assemblies opens the way to supramolecular electronics based on biological systems.}, author = {Patwardhan, Sameer and Sengupta, Sanchita and Siebbeles, Laurens D. A. and Würthner, Frank and Grozema, Ferdinand C.}, journal = {J. Am. Chem. Soc.}, keywords = {myown}, note = {PMID: 22985422}, number = 39, pages = {16147-16150}, title = {Efficient Charge Transport in Semisynthetic Zinc Chlorin Dye Assemblies}, volume = 134, year = 2012 }

  %0 Journal Article %1 doi:10.1021/ja3075192 %A Patwardhan, Sameer %A Sengupta, Sanchita %A Siebbeles, Laurens D. A. %A Würthner, Frank %A Grozema, Ferdinand C. %D 2012 %J J. Am. Chem. Soc. %N 39 %P 16147-16150 %R 10.1021/ja3075192 %T Efficient Charge Transport in Semisynthetic Zinc Chlorin Dye Assemblies %U http://dx.doi.org/10.1021/ja3075192 %V 134 %X We have studied the charge transport properties of self-assembled structures of semisynthetic zinc chlorins (ZnChls) in the solid state by pulsed radiolysis time-resolved microwave conductivity measurements. These materials can form either a two-dimensional (2D) brickwork-type slipped stack arrangement or a one-dimensional (1D) tubular assemblies, depending on the exact molecular structure of the ZnChls. We have observed efficient charge transport with mobilities as high as 0.07 cm2 V–1 s–1 for tubular assemblies of 31-hydroxy ZnChls and up to 0.28 cm2 V–1 s–1 for 2D stacked assemblies of 31-methoxy ZnChls at room temperature. The efficient charge transporting capabilities of these organized assemblies opens the way to supramolecular electronics based on biological systems.
• Alkaline earth imidazolate coordination polymers by solvent free melt synthesis as potential host lattices for rare earth photoluminescence: xinfinityAE(Im)2(ImH)2-3, Mg, Ca, Sr, Ba, x = 1-2. Zurawski, Alexander; Rybak, J.-Christoph; Meyer, Larissa V.; Matthes, Philipp R.; Stepanenko, Vladimir; Dannenbauer, Nicole; Würthner, Frank; Muller-Buschbaum, Klaus. In Dalton Trans., 41(14), pp. 4067–4078. 2012.
  • [ Abstract ]
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  The series of alkaline earth elements magnesium, calcium, strontium and barium yields single crystalline imidazolate coordination polymers by reactions of the metals with a melt of 1H-imidazole: 1infinityMg(Im)2(ImH)3 (1), 2infinityAE(Im)2(ImH)2, AE = Ca (2), Sr (3), and 1infinityBa(Im)2(ImH)2 (4). No additional solvents were used for the reactions. Co-doping experiments by addition of the rare earth elements cerium, europium and terbium were carried out. They indicate 2infinitySr(Im)2(ImH)2 as a possible host lattice for cerium(iii) photoluminescence showing a blue emission and thus a novel blue emitting hybrid material phosphor 3:Ce3+. Co-doping with europium and terbium is also possible but resulted in formation of 3infinitySr(Im)2:Ln, Ln = Eu and Tb (5), with both exhibiting green emission of either Eu2+ or Tb3+. The other alkaline earth elements do not show acceptance of the rare earth ions investigated and a different structural chemistry. For magnesium and barium one-dimensional strand structures are observed whereas calcium and strontium give two-dimensional network structures. Combined with an increase of the ionic radii of AE2+ the coordinative demand is also increasing from Mg2+ to Ba2+, reflected by four different crystal structures for the four elements Mg, Ca, Sr, Ba in 1-4. Different linkages of the imidazolate ligands result in a change from complete sigma-N coordination in 1 to additional small eta5-small pi coordination in 4. The success of co-doping with different lanthanide ions is based on a match in the chemical behaviour and cationic radii. The use of strontium for host lattices with imidazole is a rare example in coordination chemistry of co-doping with small amounts of luminescence centers and successfully reduces the amount of high price rare earth elements in hybrid materials while maintaining the properties. All compounds are examples of pure N-coordinated coordination polymers of the alkaline earth metals and were identified by single crystal X-ray analysis and powder diffraction. The degree of co-doping was determined by SEM/EDX. Mid IR, Far IR and Raman spectroscopy and micro analyses as well as simultaneous DTA/TG were also carried out to characterize the products in addition to the photoluminescence studies of the co-doped samples.

  @article{C2DT12047J, abstract = {The series of alkaline earth elements magnesium, calcium, strontium and barium yields single crystalline imidazolate coordination polymers by reactions of the metals with a melt of 1H-imidazole: 1infinityMg(Im)2(ImH)3 (1), 2infinityAE(Im)2(ImH)2, AE = Ca (2), Sr (3), and 1infinityBa(Im)2(ImH)2 (4). No additional solvents were used for the reactions. Co-doping experiments by addition of the rare earth elements cerium, europium and terbium were carried out. They indicate 2infinitySr(Im)2(ImH)2 as a possible host lattice for cerium(iii) photoluminescence showing a blue emission and thus a novel blue emitting hybrid material phosphor 3:Ce3+. Co-doping with europium and terbium is also possible but resulted in formation of 3infinitySr(Im)2:Ln, Ln = Eu and Tb (5), with both exhibiting green emission of either Eu2+ or Tb3+. The other alkaline earth elements do not show acceptance of the rare earth ions investigated and a different structural chemistry. For magnesium and barium one-dimensional strand structures are observed whereas calcium and strontium give two-dimensional network structures. Combined with an increase of the ionic radii of AE2+ the coordinative demand is also increasing from Mg2+ to Ba2+, reflected by four different crystal structures for the four elements Mg, Ca, Sr, Ba in 1-4. Different linkages of the imidazolate ligands result in a change from complete sigma-N coordination in 1 to additional small eta5-small pi coordination in 4. The success of co-doping with different lanthanide ions is based on a match in the chemical behaviour and cationic radii. The use of strontium for host lattices with imidazole is a rare example in coordination chemistry of co-doping with small amounts of luminescence centers and successfully reduces the amount of high price rare earth elements in hybrid materials while maintaining the properties. All compounds are examples of pure N-coordinated coordination polymers of the alkaline earth metals and were identified by single crystal X-ray analysis and powder diffraction. The degree of co-doping was determined by SEM/EDX. Mid IR, Far IR and Raman spectroscopy and micro analyses as well as simultaneous DTA/TG were also carried out to characterize the products in addition to the photoluminescence studies of the co-doped samples.}, author = {Zurawski, Alexander and Rybak, J.-Christoph and Meyer, Larissa V. and Matthes, Philipp R. and Stepanenko, Vladimir and Dannenbauer, Nicole and Würthner, Frank and Muller-Buschbaum, Klaus}, journal = {Dalton Trans.}, keywords = {myown}, number = 14, pages = {4067-4078}, publisher = {The Royal Society of Chemistry}, title = {Alkaline earth imidazolate coordination polymers by solvent free melt synthesis as potential host lattices for rare earth photoluminescence: xinfinityAE(Im)2(ImH)2-3, Mg, Ca, Sr, Ba, x = 1-2}, volume = 41, year = 2012 }

  %0 Journal Article %1 C2DT12047J %A Zurawski, Alexander %A Rybak, J.-Christoph %A Meyer, Larissa V. %A Matthes, Philipp R. %A Stepanenko, Vladimir %A Dannenbauer, Nicole %A Würthner, Frank %A Muller-Buschbaum, Klaus %D 2012 %I The Royal Society of Chemistry %J Dalton Trans. %N 14 %P 4067-4078 %R 10.1039/C2DT12047J %T Alkaline earth imidazolate coordination polymers by solvent free melt synthesis as potential host lattices for rare earth photoluminescence: xinfinityAE(Im)2(ImH)2-3, Mg, Ca, Sr, Ba, x = 1-2 %U http://dx.doi.org/10.1039/C2DT12047J %V 41 %X The series of alkaline earth elements magnesium, calcium, strontium and barium yields single crystalline imidazolate coordination polymers by reactions of the metals with a melt of 1H-imidazole: 1infinityMg(Im)2(ImH)3 (1), 2infinityAE(Im)2(ImH)2, AE = Ca (2), Sr (3), and 1infinityBa(Im)2(ImH)2 (4). No additional solvents were used for the reactions. Co-doping experiments by addition of the rare earth elements cerium, europium and terbium were carried out. They indicate 2infinitySr(Im)2(ImH)2 as a possible host lattice for cerium(iii) photoluminescence showing a blue emission and thus a novel blue emitting hybrid material phosphor 3:Ce3+. Co-doping with europium and terbium is also possible but resulted in formation of 3infinitySr(Im)2:Ln, Ln = Eu and Tb (5), with both exhibiting green emission of either Eu2+ or Tb3+. The other alkaline earth elements do not show acceptance of the rare earth ions investigated and a different structural chemistry. For magnesium and barium one-dimensional strand structures are observed whereas calcium and strontium give two-dimensional network structures. Combined with an increase of the ionic radii of AE2+ the coordinative demand is also increasing from Mg2+ to Ba2+, reflected by four different crystal structures for the four elements Mg, Ca, Sr, Ba in 1-4. Different linkages of the imidazolate ligands result in a change from complete sigma-N coordination in 1 to additional small eta5-small pi coordination in 4. The success of co-doping with different lanthanide ions is based on a match in the chemical behaviour and cationic radii. The use of strontium for host lattices with imidazole is a rare example in coordination chemistry of co-doping with small amounts of luminescence centers and successfully reduces the amount of high price rare earth elements in hybrid materials while maintaining the properties. All compounds are examples of pure N-coordinated coordination polymers of the alkaline earth metals and were identified by single crystal X-ray analysis and powder diffraction. The degree of co-doping was determined by SEM/EDX. Mid IR, Far IR and Raman spectroscopy and micro analyses as well as simultaneous DTA/TG were also carried out to characterize the products in addition to the photoluminescence studies of the co-doped samples.
• Alkaline earth imidazolate coordination polymers by solvent free melt synthesis as potential host lattices for rare earth photoluminescence: xinfinityAE(Im)2(ImH)2-3, Mg, Ca, Sr, Ba, x = 1-2. Zurawski, Alexander; Rybak, J.-Christoph; Meyer, Larissa V.; Matthes, Philipp R.; Stepanenko, Vladimir; Dannenbauer, Nicole; Würthner, Frank; Muller-Buschbaum, Klaus. In Dalton Trans., 41(14), pp. 4067–4078. 2012.
  • [ Abstract ]
  • [ BibTeX ]
  • [ EndNote ]
  • [ DOI ]
  The series of alkaline earth elements magnesium, calcium, strontium and barium yields single crystalline imidazolate coordination polymers by reactions of the metals with a melt of 1H-imidazole: 1infinityMg(Im)2(ImH)3 (1), 2infinityAE(Im)2(ImH)2, AE = Ca (2), Sr (3), and 1infinityBa(Im)2(ImH)2 (4). No additional solvents were used for the reactions. Co-doping experiments by addition of the rare earth elements cerium, europium and terbium were carried out. They indicate 2infinitySr(Im)2(ImH)2 as a possible host lattice for cerium(iii) photoluminescence showing a blue emission and thus a novel blue emitting hybrid material phosphor 3:Ce3+. Co-doping with europium and terbium is also possible but resulted in formation of 3infinitySr(Im)2:Ln, Ln = Eu and Tb (5), with both exhibiting green emission of either Eu2+ or Tb3+. The other alkaline earth elements do not show acceptance of the rare earth ions investigated and a different structural chemistry. For magnesium and barium one-dimensional strand structures are observed whereas calcium and strontium give two-dimensional network structures. Combined with an increase of the ionic radii of AE2+ the coordinative demand is also increasing from Mg2+ to Ba2+, reflected by four different crystal structures for the four elements Mg, Ca, Sr, Ba in 1-4. Different linkages of the imidazolate ligands result in a change from complete sigma-N coordination in 1 to additional small eta5-small pi coordination in 4. The success of co-doping with different lanthanide ions is based on a match in the chemical behaviour and cationic radii. The use of strontium for host lattices with imidazole is a rare example in coordination chemistry of co-doping with small amounts of luminescence centers and successfully reduces the amount of high price rare earth elements in hybrid materials while maintaining the properties. All compounds are examples of pure N-coordinated coordination polymers of the alkaline earth metals and were identified by single crystal X-ray analysis and powder diffraction. The degree of co-doping was determined by SEM/EDX. Mid IR, Far IR and Raman spectroscopy and micro analyses as well as simultaneous DTA/TG were also carried out to characterize the products in addition to the photoluminescence studies of the co-doped samples.

  @article{C2DT12047J, abstract = {The series of alkaline earth elements magnesium, calcium, strontium and barium yields single crystalline imidazolate coordination polymers by reactions of the metals with a melt of 1H-imidazole: 1infinityMg(Im)2(ImH)3 (1), 2infinityAE(Im)2(ImH)2, AE = Ca (2), Sr (3), and 1infinityBa(Im)2(ImH)2 (4). No additional solvents were used for the reactions. Co-doping experiments by addition of the rare earth elements cerium, europium and terbium were carried out. They indicate 2infinitySr(Im)2(ImH)2 as a possible host lattice for cerium(iii) photoluminescence showing a blue emission and thus a novel blue emitting hybrid material phosphor 3:Ce3+. Co-doping with europium and terbium is also possible but resulted in formation of 3infinitySr(Im)2:Ln, Ln = Eu and Tb (5), with both exhibiting green emission of either Eu2+ or Tb3+. The other alkaline earth elements do not show acceptance of the rare earth ions investigated and a different structural chemistry. For magnesium and barium one-dimensional strand structures are observed whereas calcium and strontium give two-dimensional network structures. Combined with an increase of the ionic radii of AE2+ the coordinative demand is also increasing from Mg2+ to Ba2+, reflected by four different crystal structures for the four elements Mg, Ca, Sr, Ba in 1-4. Different linkages of the imidazolate ligands result in a change from complete sigma-N coordination in 1 to additional small eta5-small pi coordination in 4. The success of co-doping with different lanthanide ions is based on a match in the chemical behaviour and cationic radii. The use of strontium for host lattices with imidazole is a rare example in coordination chemistry of co-doping with small amounts of luminescence centers and successfully reduces the amount of high price rare earth elements in hybrid materials while maintaining the properties. All compounds are examples of pure N-coordinated coordination polymers of the alkaline earth metals and were identified by single crystal X-ray analysis and powder diffraction. The degree of co-doping was determined by SEM/EDX. Mid IR, Far IR and Raman spectroscopy and micro analyses as well as simultaneous DTA/TG were also carried out to characterize the products in addition to the photoluminescence studies of the co-doped samples.}, author = {Zurawski, Alexander and Rybak, J.-Christoph and Meyer, Larissa V. and Matthes, Philipp R. and Stepanenko, Vladimir and Dannenbauer, Nicole and Würthner, Frank and Muller-Buschbaum, Klaus}, journal = {Dalton Trans.}, keywords = {myown}, number = 14, pages = {4067-4078}, publisher = {The Royal Society of Chemistry}, title = {Alkaline earth imidazolate coordination polymers by solvent free melt synthesis as potential host lattices for rare earth photoluminescence: xinfinityAE(Im)2(ImH)2-3, Mg, Ca, Sr, Ba, x = 1-2}, volume = 41, year = 2012 }

  %0 Journal Article %1 C2DT12047J %A Zurawski, Alexander %A Rybak, J.-Christoph %A Meyer, Larissa V. %A Matthes, Philipp R. %A Stepanenko, Vladimir %A Dannenbauer, Nicole %A Würthner, Frank %A Muller-Buschbaum, Klaus %D 2012 %I The Royal Society of Chemistry %J Dalton Trans. %N 14 %P 4067-4078 %R 10.1039/C2DT12047J %T Alkaline earth imidazolate coordination polymers by solvent free melt synthesis as potential host lattices for rare earth photoluminescence: xinfinityAE(Im)2(ImH)2-3, Mg, Ca, Sr, Ba, x = 1-2 %U http://dx.doi.org/10.1039/C2DT12047J %V 41 %X The series of alkaline earth elements magnesium, calcium, strontium and barium yields single crystalline imidazolate coordination polymers by reactions of the metals with a melt of 1H-imidazole: 1infinityMg(Im)2(ImH)3 (1), 2infinityAE(Im)2(ImH)2, AE = Ca (2), Sr (3), and 1infinityBa(Im)2(ImH)2 (4). No additional solvents were used for the reactions. Co-doping experiments by addition of the rare earth elements cerium, europium and terbium were carried out. They indicate 2infinitySr(Im)2(ImH)2 as a possible host lattice for cerium(iii) photoluminescence showing a blue emission and thus a novel blue emitting hybrid material phosphor 3:Ce3+. Co-doping with europium and terbium is also possible but resulted in formation of 3infinitySr(Im)2:Ln, Ln = Eu and Tb (5), with both exhibiting green emission of either Eu2+ or Tb3+. The other alkaline earth elements do not show acceptance of the rare earth ions investigated and a different structural chemistry. For magnesium and barium one-dimensional strand structures are observed whereas calcium and strontium give two-dimensional network structures. Combined with an increase of the ionic radii of AE2+ the coordinative demand is also increasing from Mg2+ to Ba2+, reflected by four different crystal structures for the four elements Mg, Ca, Sr, Ba in 1-4. Different linkages of the imidazolate ligands result in a change from complete sigma-N coordination in 1 to additional small eta5-small pi coordination in 4. The success of co-doping with different lanthanide ions is based on a match in the chemical behaviour and cationic radii. The use of strontium for host lattices with imidazole is a rare example in coordination chemistry of co-doping with small amounts of luminescence centers and successfully reduces the amount of high price rare earth elements in hybrid materials while maintaining the properties. All compounds are examples of pure N-coordinated coordination polymers of the alkaline earth metals and were identified by single crystal X-ray analysis and powder diffraction. The degree of co-doping was determined by SEM/EDX. Mid IR, Far IR and Raman spectroscopy and micro analyses as well as simultaneous DTA/TG were also carried out to characterize the products in addition to the photoluminescence studies of the co-doped samples.
• Reorganization of perylene bisimide J-aggregates: from delocalized collective to localized individual excitations. Tian, Yuxi; Stepanenko, Vladimir; Kaiser, Theo E.; Würthner, Frank; Scheblykin, Ivan G. In Nanoscale, 4(1), pp. 218–223. 2012.
  • [ Abstract ]
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  Water-induced reorganization of individual one-dimensional J-aggregates of perylene bisimide (PBI) dyes was observed by fluorescence microscopy. Fluorescence spectra and decay kinetics of individual J-aggregates immobilized on glass surfaces were measured under a dry nitrogen atmosphere and under humid conditions. The fluorescence properties of PBI J-aggregates arisen from collective excitons under dry nitrogen atmosphere were changed to those of non-interacting dye monomers when water vapor was introduced into the environment (sample chamber). Time-dependent changes of the fluorescence spectra and lifetimes upon exposure to water vapor suggest an initial coordination of water molecules at defect sites leading to the formation of H-type dimer units that act as exciton quenchers, and a subsequent slower disintegration of the hydrogen-bonded J-aggregate into monomers that lack resonance coupling. Our present studies resulted in a direct demonstration of how drastically the optical properties of molecular ensembles and characteristics of their excited states can be changed by delicate reorganization of dye molecules at nanometre scales.

  @article{C1NR10973A, abstract = {Water-induced reorganization of individual one-dimensional J-aggregates of perylene bisimide (PBI) dyes was observed by fluorescence microscopy. Fluorescence spectra and decay kinetics of individual J-aggregates immobilized on glass surfaces were measured under a dry nitrogen atmosphere and under humid conditions. The fluorescence properties of PBI J-aggregates arisen from collective excitons under dry nitrogen atmosphere were changed to those of non-interacting dye monomers when water vapor was introduced into the environment (sample chamber). Time-dependent changes of the fluorescence spectra and lifetimes upon exposure to water vapor suggest an initial coordination of water molecules at defect sites leading to the formation of H-type dimer units that act as exciton quenchers{,} and a subsequent slower disintegration of the hydrogen-bonded J-aggregate into monomers that lack resonance coupling. Our present studies resulted in a direct demonstration of how drastically the optical properties of molecular ensembles and characteristics of their excited states can be changed by delicate reorganization of dye molecules at nanometre scales.}, author = {Tian, Yuxi and Stepanenko, Vladimir and Kaiser, Theo E. and Würthner, Frank and Scheblykin, Ivan G.}, journal = {Nanoscale}, keywords = {myown}, number = 1, pages = {218-223}, publisher = {The Royal Society of Chemistry}, title = {Reorganization of perylene bisimide J-aggregates: from delocalized collective to localized individual excitations}, volume = 4, year = 2012 }

  %0 Journal Article %1 C1NR10973A %A Tian, Yuxi %A Stepanenko, Vladimir %A Kaiser, Theo E. %A Würthner, Frank %A Scheblykin, Ivan G. %D 2012 %I The Royal Society of Chemistry %J Nanoscale %N 1 %P 218-223 %R 10.1039/C1NR10973A %T Reorganization of perylene bisimide J-aggregates: from delocalized collective to localized individual excitations %U http://dx.doi.org/10.1039/C1NR10973A %V 4 %X Water-induced reorganization of individual one-dimensional J-aggregates of perylene bisimide (PBI) dyes was observed by fluorescence microscopy. Fluorescence spectra and decay kinetics of individual J-aggregates immobilized on glass surfaces were measured under a dry nitrogen atmosphere and under humid conditions. The fluorescence properties of PBI J-aggregates arisen from collective excitons under dry nitrogen atmosphere were changed to those of non-interacting dye monomers when water vapor was introduced into the environment (sample chamber). Time-dependent changes of the fluorescence spectra and lifetimes upon exposure to water vapor suggest an initial coordination of water molecules at defect sites leading to the formation of H-type dimer units that act as exciton quenchers, and a subsequent slower disintegration of the hydrogen-bonded J-aggregate into monomers that lack resonance coupling. Our present studies resulted in a direct demonstration of how drastically the optical properties of molecular ensembles and characteristics of their excited states can be changed by delicate reorganization of dye molecules at nanometre scales.
• Interaction of spermine-alanine functionalized perylene bisimide dye aggregates with ds-DNA/RNA secondary structure. Rehm, Thomas H.; Stojkovic, Marijana Radic; Rehm, Stefanie; Skugor, Marko; Piantanida, Ivo; Würthner, Frank. In Chem. Sci., 3(12), pp. 3393–3397. 2012.
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  We report for the first time on the interaction of self-assembled perylene bisimide (PBI) dye aggregates with polynucleotides, revealing very high (nM) binding constants and exceptional thermal stabilization of double-stranded (ds)-DNA/RNA. Induced CD profiles of PBI dimer aggregates formed within DNA/RNA grooves show high sensitivity on the steric properties of the binding site, suggesting the applicability of such self-adjusting excitonically coupled PBI dimers for the sensing of the DNA/RNA secondary structure.

  @article{C2SC20825C, abstract = {We report for the first time on the interaction of self-assembled perylene bisimide (PBI) dye aggregates with polynucleotides{,} revealing very high (nM) binding constants and exceptional thermal stabilization of double-stranded (ds)-DNA/RNA. Induced CD profiles of PBI dimer aggregates formed within DNA/RNA grooves show high sensitivity on the steric properties of the binding site{,} suggesting the applicability of such self-adjusting excitonically coupled PBI dimers for the sensing of the DNA/RNA secondary structure.}, author = {Rehm, Thomas H. and Stojkovic, Marijana Radic and Rehm, Stefanie and Skugor, Marko and Piantanida, Ivo and Würthner, Frank}, journal = {Chem. Sci.}, keywords = {myown}, number = 12, pages = {3393-3397}, publisher = {The Royal Society of Chemistry}, title = {Interaction of spermine-alanine functionalized perylene bisimide dye aggregates with ds-DNA/RNA secondary structure}, volume = 3, year = 2012 }

  %0 Journal Article %1 C2SC20825C %A Rehm, Thomas H. %A Stojkovic, Marijana Radic %A Rehm, Stefanie %A Skugor, Marko %A Piantanida, Ivo %A Würthner, Frank %D 2012 %I The Royal Society of Chemistry %J Chem. Sci. %N 12 %P 3393-3397 %R 10.1039/C2SC20825C %T Interaction of spermine-alanine functionalized perylene bisimide dye aggregates with ds-DNA/RNA secondary structure %U http://dx.doi.org/10.1039/C2SC20825C %V 3 %X We report for the first time on the interaction of self-assembled perylene bisimide (PBI) dye aggregates with polynucleotides, revealing very high (nM) binding constants and exceptional thermal stabilization of double-stranded (ds)-DNA/RNA. Induced CD profiles of PBI dimer aggregates formed within DNA/RNA grooves show high sensitivity on the steric properties of the binding site, suggesting the applicability of such self-adjusting excitonically coupled PBI dimers for the sensing of the DNA/RNA secondary structure.
• Perylene Bisimide Dimer Aggregates: Fundamental Insights into Self-Assembly by NMR and UV/Vis Spectroscopy. Shao, Changzhun; Grüne, Matthias; Stolte, Matthias; Würthner, Frank. In Chemistry – A European Journal, 18(43), pp. 13665–13677. 2012.
  • [ Abstract ]
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  A novel perylene bisimide (PBI) dye bearing one solubilizing dialkoxybenzyl and one bulky 2,5-di-tert-butylphenyl substituent was synthesized and its aggregation behavior was analyzed by NMR and UV/Vis spectroscopy in various chloroform/methylcyclohexane (MCH) solvent mixtures. In the presence of no less than 10 vol % chloroform, exclusive self-assembly of this PBI dye into π-stacked dimers was unambiguously confirmed by means of both concentration-dependent 1H NMR and UV/Vis spectroscopic experiments. Based on ROESY NMR, a well-defined π-stacked dimer structure was determined and further corroborated by molecular modeling studies. By varying the solvent composition of chloroform and MCH, the solvent effects on the Gibbs free energy of PBI dimerization were elucidated and showed a pronounced nonlinearity between lower and higher MCH contents. This observation could be related to a further growth process of dimers into larger aggregates that occurs in the absence of chloroform, which is required to solvate the aromatic π surfaces. With the help of a single-crystal structure analysis for a related PBI dye, a structural model could be derived for the extended aggregates that are still composed of defined π–π-stacked PBI dimer entities.

  @article{CHEM:CHEM201201661, abstract = {A novel perylene bisimide (PBI) dye bearing one solubilizing dialkoxybenzyl and one bulky 2,5-di-tert-butylphenyl substituent was synthesized and its aggregation behavior was analyzed by NMR and UV/Vis spectroscopy in various chloroform/methylcyclohexane (MCH) solvent mixtures. In the presence of no less than 10 vol % chloroform, exclusive self-assembly of this PBI dye into π-stacked dimers was unambiguously confirmed by means of both concentration-dependent 1H NMR and UV/Vis spectroscopic experiments. Based on ROESY NMR, a well-defined π-stacked dimer structure was determined and further corroborated by molecular modeling studies. By varying the solvent composition of chloroform and MCH, the solvent effects on the Gibbs free energy of PBI dimerization were elucidated and showed a pronounced nonlinearity between lower and higher MCH contents. This observation could be related to a further growth process of dimers into larger aggregates that occurs in the absence of chloroform, which is required to solvate the aromatic π surfaces. With the help of a single-crystal structure analysis for a related PBI dye, a structural model could be derived for the extended aggregates that are still composed of defined π–π-stacked PBI dimer entities.}, author = {Shao, Changzhun and Grüne, Matthias and Stolte, Matthias and Würthner, Frank}, journal = {Chemistry – A European Journal}, keywords = {myown}, number = 43, pages = {13665–13677}, publisher = {WILEY-VCH Verlag}, title = {Perylene Bisimide Dimer Aggregates: Fundamental Insights into Self-Assembly by NMR and UV/Vis Spectroscopy}, volume = 18, year = 2012 }

  %0 Journal Article %1 CHEM:CHEM201201661 %A Shao, Changzhun %A Grüne, Matthias %A Stolte, Matthias %A Würthner, Frank %D 2012 %I WILEY-VCH Verlag %J Chemistry – A European Journal %N 43 %P 13665--13677 %R 10.1002/chem.201201661 %T Perylene Bisimide Dimer Aggregates: Fundamental Insights into Self-Assembly by NMR and UV/Vis Spectroscopy %U http://dx.doi.org/10.1002/chem.201201661 %V 18 %X A novel perylene bisimide (PBI) dye bearing one solubilizing dialkoxybenzyl and one bulky 2,5-di-tert-butylphenyl substituent was synthesized and its aggregation behavior was analyzed by NMR and UV/Vis spectroscopy in various chloroform/methylcyclohexane (MCH) solvent mixtures. In the presence of no less than 10 vol % chloroform, exclusive self-assembly of this PBI dye into π-stacked dimers was unambiguously confirmed by means of both concentration-dependent 1H NMR and UV/Vis spectroscopic experiments. Based on ROESY NMR, a well-defined π-stacked dimer structure was determined and further corroborated by molecular modeling studies. By varying the solvent composition of chloroform and MCH, the solvent effects on the Gibbs free energy of PBI dimerization were elucidated and showed a pronounced nonlinearity between lower and higher MCH contents. This observation could be related to a further growth process of dimers into larger aggregates that occurs in the absence of chloroform, which is required to solvate the aromatic π surfaces. With the help of a single-crystal structure analysis for a related PBI dye, a structural model could be derived for the extended aggregates that are still composed of defined π–π-stacked PBI dimer entities.
• Comparative analysis of the energy levels of planar and core-twisted perylene bisimides in solution and solid state by UV/VIS, CV, and UPS/IPES. Arantes, C.; Scholz, M.; Schmidt, R.; Dehm, V.; Rocco, M. L. M.; Schöll, A.; Reinert, F.; Würthner, F. In Applied Physics A, 108(3), pp. 629–637. 2012.
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  The frontier orbital energies of four different functionalized perylene bisimide derivatives, PBI-Ph(iPr)2, PBI-H4, PBI-F2 and PBI-Cl4, were directly determined by UV-photo electron spectroscopy (UPS) and inverse photo electron spectroscopy (IPES) and are compared to the results from cyclic voltammetry (CV) and optical absorption spectroscopy (UV/VIS). The optical spectra reveal significant differences between monomeric species in solution and assembled molecules in the condensed state for the nearly planar PBI-H4 and PBI-F2, which are attributed to significant $\pi$--$\pi$ stacking interactions in the condensed phase. In contrast, for PBIs with bulky substituents or twisted core, i.e. 2,6-isopropylphenyl substituents at the imide positions (PBI-Ph(iPr)2) or four chlorine substituents at perylene bay positions (PBI-Cl4), similar spectra are observed in solution and in the condensed state, which suggests the absence of strong intermolecular $\pi$--$\pi$ stacking interactions. An entirely different result is obtained for the HOMO/LUMO energy values obtained from UPS/IPES and CV measurements which do not reveal a significant impact of intermolecular $\pi$--$\pi$ stacking interactions. When comparing CV and UPS/IPES results, an accentuated deviation was observed for the perylene bisimide derivatives as compared to correlations found in the literature.

  @article{Arantes2012, abstract = {The frontier orbital energies of four different functionalized perylene bisimide derivatives, PBI-Ph(iPr)2, PBI-H4, PBI-F2 and PBI-Cl4, were directly determined by UV-photo electron spectroscopy (UPS) and inverse photo electron spectroscopy (IPES) and are compared to the results from cyclic voltammetry (CV) and optical absorption spectroscopy (UV/VIS). The optical spectra reveal significant differences between monomeric species in solution and assembled molecules in the condensed state for the nearly planar PBI-H4 and PBI-F2, which are attributed to significant $\pi$–$\pi$ stacking interactions in the condensed phase. In contrast, for PBIs with bulky substituents or twisted core, i.e. 2,6-isopropylphenyl substituents at the imide positions (PBI-Ph(iPr)2) or four chlorine substituents at perylene bay positions (PBI-Cl4), similar spectra are observed in solution and in the condensed state, which suggests the absence of strong intermolecular $\pi$–$\pi$ stacking interactions. An entirely different result is obtained for the HOMO/LUMO energy values obtained from UPS/IPES and CV measurements which do not reveal a significant impact of intermolecular $\pi$–$\pi$ stacking interactions. When comparing CV and UPS/IPES results, an accentuated deviation was observed for the perylene bisimide derivatives as compared to correlations found in the literature.}, author = {Arantes, C. and Scholz, M. and Schmidt, R. and Dehm, V. and Rocco, M. L. M. and Schöll, A. and Reinert, F. and Würthner, F.}, journal = {Applied Physics A}, keywords = {myown}, month = {09}, number = 3, pages = {629–637}, title = {Comparative analysis of the energy levels of planar and core-twisted perylene bisimides in solution and solid state by UV/VIS, CV, and UPS/IPES}, volume = 108, year = 2012 }

  %0 Journal Article %1 Arantes2012 %A Arantes, C. %A Scholz, M. %A Schmidt, R. %A Dehm, V. %A Rocco, M. L. M. %A Schöll, A. %A Reinert, F. %A Würthner, F. %D 2012 %J Applied Physics A %N 3 %P 629--637 %R 10.1007/s00339-012-6941-3 %T Comparative analysis of the energy levels of planar and core-twisted perylene bisimides in solution and solid state by UV/VIS, CV, and UPS/IPES %U https://doi.org/10.1007/s00339-012-6941-3 %V 108 %X The frontier orbital energies of four different functionalized perylene bisimide derivatives, PBI-Ph(iPr)2, PBI-H4, PBI-F2 and PBI-Cl4, were directly determined by UV-photo electron spectroscopy (UPS) and inverse photo electron spectroscopy (IPES) and are compared to the results from cyclic voltammetry (CV) and optical absorption spectroscopy (UV/VIS). The optical spectra reveal significant differences between monomeric species in solution and assembled molecules in the condensed state for the nearly planar PBI-H4 and PBI-F2, which are attributed to significant $\pi$--$\pi$ stacking interactions in the condensed phase. In contrast, for PBIs with bulky substituents or twisted core, i.e. 2,6-isopropylphenyl substituents at the imide positions (PBI-Ph(iPr)2) or four chlorine substituents at perylene bay positions (PBI-Cl4), similar spectra are observed in solution and in the condensed state, which suggests the absence of strong intermolecular $\pi$--$\pi$ stacking interactions. An entirely different result is obtained for the HOMO/LUMO energy values obtained from UPS/IPES and CV measurements which do not reveal a significant impact of intermolecular $\pi$--$\pi$ stacking interactions. When comparing CV and UPS/IPES results, an accentuated deviation was observed for the perylene bisimide derivatives as compared to correlations found in the literature.
• Terrylene bisimide-diarylethene photochromic switch. Berberich, Martin; Würthner, Frank. In Chem. Sci., 3(9), pp. 2771–2777. 2012.
  • [ Abstract ]
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  A new photochromic system 2o/2c based on a highly photostable terrylene bisimide (TBI) fluorophore and a diarylethene (DAE) photochrome has been synthesised and its photoswitching properties have been investigated by UV/vis absorption and fluorescence spectroscopy and by cyclic voltammetry. Our detailed studies reveal that the fluorescence of this system is photoswitchable by reversible modulation of intramolecular electron transfer (PET). Cyclovoltammetry measurements have shown that the reduction potentials of the open and closed form of the DAE moiety of this photochromic system differ significantly, thus the electron transfer from the excited TBI donor takes places only to the closed form of DAE acceptor. Accordingly, switching between both states of the DAE unit by irradiation with UV and visible light leads to a significant difference in fluorescence quantum yields of TBI unit of open 2o and closed form 2c. The driving force for the emission quenching by PET has been estimated by the Rehm-Weller equation, providing a [capital Delta]G[degree] value of -0.24 eV for the closed form, while this value is positive (0.16 eV) for the open form. The photostability of the present system has been proven by repeating switching cycles performed by alternating irradiation with UV and visible light.

  @article{C2SC20554H, abstract = {A new photochromic system 2o/2c based on a highly photostable terrylene bisimide (TBI) fluorophore and a diarylethene (DAE) photochrome has been synthesised and its photoswitching properties have been investigated by UV/vis absorption and fluorescence spectroscopy and by cyclic voltammetry. Our detailed studies reveal that the fluorescence of this system is photoswitchable by reversible modulation of intramolecular electron transfer (PET). Cyclovoltammetry measurements have shown that the reduction potentials of the open and closed form of the DAE moiety of this photochromic system differ significantly{,} thus the electron transfer from the excited TBI donor takes places only to the closed form of DAE acceptor. Accordingly{,} switching between both states of the DAE unit by irradiation with UV and visible light leads to a significant difference in fluorescence quantum yields of TBI unit of open 2o and closed form 2c. The driving force for the emission quenching by PET has been estimated by the Rehm-Weller equation{,} providing a [capital Delta]G[degree] value of -0.24 eV for the closed form{,} while this value is positive (0.16 eV) for the open form. The photostability of the present system has been proven by repeating switching cycles performed by alternating irradiation with UV and visible light.}, author = {Berberich, Martin and Würthner, Frank}, journal = {Chem. Sci.}, keywords = {myown}, number = 9, pages = {2771-2777}, publisher = {The Royal Society of Chemistry}, title = {Terrylene bisimide-diarylethene photochromic switch}, volume = 3, year = 2012 }

  %0 Journal Article %1 C2SC20554H %A Berberich, Martin %A Würthner, Frank %D 2012 %I The Royal Society of Chemistry %J Chem. Sci. %N 9 %P 2771-2777 %R 10.1039/C2SC20554H %T Terrylene bisimide-diarylethene photochromic switch %U http://dx.doi.org/10.1039/C2SC20554H %V 3 %X A new photochromic system 2o/2c based on a highly photostable terrylene bisimide (TBI) fluorophore and a diarylethene (DAE) photochrome has been synthesised and its photoswitching properties have been investigated by UV/vis absorption and fluorescence spectroscopy and by cyclic voltammetry. Our detailed studies reveal that the fluorescence of this system is photoswitchable by reversible modulation of intramolecular electron transfer (PET). Cyclovoltammetry measurements have shown that the reduction potentials of the open and closed form of the DAE moiety of this photochromic system differ significantly, thus the electron transfer from the excited TBI donor takes places only to the closed form of DAE acceptor. Accordingly, switching between both states of the DAE unit by irradiation with UV and visible light leads to a significant difference in fluorescence quantum yields of TBI unit of open 2o and closed form 2c. The driving force for the emission quenching by PET has been estimated by the Rehm-Weller equation, providing a [capital Delta]G[degree] value of -0.24 eV for the closed form, while this value is positive (0.16 eV) for the open form. The photostability of the present system has been proven by repeating switching cycles performed by alternating irradiation with UV and visible light.
• High-Performance Organic Thin-Film Transistor Based on a Dipolar Organic Semiconductor. Huang, Lizhen; Stolte, Matthias; Bürckstümmer, Hannah; Würthner, Frank. In Advanced Materials, 24(42), pp. 5750–5754. 2012.
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  @article{ADMA:ADMA201202441, author = {Huang, Lizhen and Stolte, Matthias and Bürckstümmer, Hannah and Würthner, Frank}, journal = {Advanced Materials}, keywords = {myown}, number = 42, pages = {5750–5754}, publisher = {WILEY-VCH Verlag}, title = {High-Performance Organic Thin-Film Transistor Based on a Dipolar Organic Semiconductor}, volume = 24, year = 2012 }

  %0 Journal Article %1 ADMA:ADMA201202441 %A Huang, Lizhen %A Stolte, Matthias %A Bürckstümmer, Hannah %A Würthner, Frank %D 2012 %I WILEY-VCH Verlag %J Advanced Materials %N 42 %P 5750--5754 %R 10.1002/adma.201202441 %T High-Performance Organic Thin-Film Transistor Based on a Dipolar Organic Semiconductor %U http://dx.doi.org/10.1002/adma.201202441 %V 24
• Improved ambient operation of n-channel organic transistors of solution-sheared naphthalene diimide under bias stress. Stolte, Matthias; Gsanger, Marcel; Hofmockel, Robert; Suraru, Sabin-Lucian; Würthner, Frank. In Phys. Chem. Chem. Phys., 14(41), pp. 14181–14185. 2012.
  • [ Abstract ]
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  Large arrays of n-channel organic thin film transistors of a core-chlorinated naphthalene diimide were processed by solution shearing on a silicon dioxide dielectric exhibiting ambient stable electron mobilities of up to 0.95 cm2 V-1 s-1. Under bias stress an increase in effective charge carrier mobility of up to 4.26 cm2 V-1 s-1 has been observed.

  @article{C2CP41552F, abstract = {Large arrays of n-channel organic thin film transistors of a core-chlorinated naphthalene diimide were processed by solution shearing on a silicon dioxide dielectric exhibiting ambient stable electron mobilities of up to 0.95 cm2 V-1 s-1. Under bias stress an increase in effective charge carrier mobility of up to 4.26 cm2 V-1 s-1 has been observed.}, author = {Stolte, Matthias and Gsanger, Marcel and Hofmockel, Robert and Suraru, Sabin-Lucian and Würthner, Frank}, journal = {Phys. Chem. Chem. Phys.}, keywords = {myown}, number = 41, pages = {14181-14185}, publisher = {The Royal Society of Chemistry}, title = {Improved ambient operation of n-channel organic transistors of solution-sheared naphthalene diimide under bias stress}, volume = 14, year = 2012 }

  %0 Journal Article %1 C2CP41552F %A Stolte, Matthias %A Gsanger, Marcel %A Hofmockel, Robert %A Suraru, Sabin-Lucian %A Würthner, Frank %D 2012 %I The Royal Society of Chemistry %J Phys. Chem. Chem. Phys. %N 41 %P 14181-14185 %R 10.1039/C2CP41552F %T Improved ambient operation of n-channel organic transistors of solution-sheared naphthalene diimide under bias stress %U http://dx.doi.org/10.1039/C2CP41552F %V 14 %X Large arrays of n-channel organic thin film transistors of a core-chlorinated naphthalene diimide were processed by solution shearing on a silicon dioxide dielectric exhibiting ambient stable electron mobilities of up to 0.95 cm2 V-1 s-1. Under bias stress an increase in effective charge carrier mobility of up to 4.26 cm2 V-1 s-1 has been observed.
• Molecular Assemblies of Perylene Bisimide Dyes in Water. Görl, Daniel; Zhang, Xin; Würthner, Frank. In Angew. Chem. Int. Ed., 51, pp. 6328–6348. 2012.
  • [ Abstract ]
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  Perylene bisimides are among the most valuable functional dyes and have numerous potential applications. As a result of their chemical robustness, photostability, and outstanding optical and electronic properties, these dyes have been applied as pigments, fluorescence sensors, and n‐semiconductors in organic electronics and photovoltaics. Moreover, the extended quadrupolar π system of this class of dyes has facilitated the construction of numerous supramolecular architectures with fascinating photophysical properties. However, the supramolecular approach to the formation of perylene bisimide aggregates has been restricted mostly to organic media. Pleasingly, considerable progress has been made in the last few years in developing water‐soluble perylene bisimides and their application in aqueous media. This Review provides an up‐to‐date overview on the self‐assembly of perylene bisimides through π–π interactions in aqueous media. Synthetic strategies for the preparation of water‐soluble perylene bisimides and the influence of water on the π–π stacking of perylene bisimides as well as the resulting applications are discussed.

  @article{grl2012molecular, abstract = {Perylene bisimides are among the most valuable functional dyes and have numerous potential applications. As a result of their chemical robustness, photostability, and outstanding optical and electronic properties, these dyes have been applied as pigments, fluorescence sensors, and n‐semiconductors in organic electronics and photovoltaics. Moreover, the extended quadrupolar π system of this class of dyes has facilitated the construction of numerous supramolecular architectures with fascinating photophysical properties. However, the supramolecular approach to the formation of perylene bisimide aggregates has been restricted mostly to organic media. Pleasingly, considerable progress has been made in the last few years in developing water‐soluble perylene bisimides and their application in aqueous media. This Review provides an up‐to‐date overview on the self‐assembly of perylene bisimides through π–π interactions in aqueous media. Synthetic strategies for the preparation of water‐soluble perylene bisimides and the influence of water on the π–π stacking of perylene bisimides as well as the resulting applications are discussed.}, author = {Görl, Daniel and Zhang, Xin and Würthner, Frank}, journal = {Angew. Chem. Int. Ed.}, keywords = {myown}, pages = {6328 - 6348}, publisher = {WILEY-VCH Verlag}, title = {Molecular Assemblies of Perylene Bisimide Dyes in Water}, volume = 51, year = 2012 }

  %0 Journal Article %1 grl2012molecular %A Görl, Daniel %A Zhang, Xin %A Würthner, Frank %D 2012 %I WILEY-VCH Verlag %J Angew. Chem. Int. Ed. %P 6328 - 6348 %R 10.1002/anie.201108690 %T Molecular Assemblies of Perylene Bisimide Dyes in Water %U https://onlinelibrary.wiley.com/doi/10.1002/anie.201108690 %V 51 %X Perylene bisimides are among the most valuable functional dyes and have numerous potential applications. As a result of their chemical robustness, photostability, and outstanding optical and electronic properties, these dyes have been applied as pigments, fluorescence sensors, and n‐semiconductors in organic electronics and photovoltaics. Moreover, the extended quadrupolar π system of this class of dyes has facilitated the construction of numerous supramolecular architectures with fascinating photophysical properties. However, the supramolecular approach to the formation of perylene bisimide aggregates has been restricted mostly to organic media. Pleasingly, considerable progress has been made in the last few years in developing water‐soluble perylene bisimides and their application in aqueous media. This Review provides an up‐to‐date overview on the self‐assembly of perylene bisimides through π–π interactions in aqueous media. Synthetic strategies for the preparation of water‐soluble perylene bisimides and the influence of water on the π–π stacking of perylene bisimides as well as the resulting applications are discussed.
• p-Doped Multiwall Carbon Nanotube/Perylene Diimide Derivative Photoelectrochemical Cells for Photocurrent Generation. Troeger, Anna; Ledendecker, Marc; Margraf, Johannes T.; Sgobba, Vito; Guldi, Dirk M.; Vieweg, Benito F.; Spiecker, Erdmann; Suraru, Sabin-Lucian; Würthner, Frank. In Advanced Energy Materials, 2(5), pp. 536–540. 2012.
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  @article{AENM:AENM201100710, author = {Troeger, Anna and Ledendecker, Marc and Margraf, Johannes T. and Sgobba, Vito and Guldi, Dirk M. and Vieweg, Benito F. and Spiecker, Erdmann and Suraru, Sabin-Lucian and Würthner, Frank}, journal = {Advanced Energy Materials}, keywords = {myown}, number = 5, pages = {536–540}, publisher = {WILEY-VCH Verlag}, title = {p-Doped Multiwall Carbon Nanotube/Perylene Diimide Derivative Photoelectrochemical Cells for Photocurrent Generation}, volume = 2, year = 2012 }

  %0 Journal Article %1 AENM:AENM201100710 %A Troeger, Anna %A Ledendecker, Marc %A Margraf, Johannes T. %A Sgobba, Vito %A Guldi, Dirk M. %A Vieweg, Benito F. %A Spiecker, Erdmann %A Suraru, Sabin-Lucian %A Würthner, Frank %D 2012 %I WILEY-VCH Verlag %J Advanced Energy Materials %N 5 %P 536--540 %R 10.1002/aenm.201100710 %T p-Doped Multiwall Carbon Nanotube/Perylene Diimide Derivative Photoelectrochemical Cells for Photocurrent Generation %U http://dx.doi.org/10.1002/aenm.201100710 %V 2
• Planar, bulk and hybrid merocyanine/C60 heterojunction devices: a case study on thin film morphology and photovoltaic performance. Ojala, Antti; Burckstummer, Hannah; Hwang, Jaehyung; Graf, Katja; von Vacano, Bernhard; Meerholz, Klaus; Erk, Peter; Würthner, Frank. In J. Mater. Chem., 22(10), pp. 4473–4482. 2012.
  • [ Abstract ]
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  The growth of a thermally deposited merocyanine (HB364) thin film can be modified through insertion of a transition metal oxide layer between an indium tin oxide (ITO) covered glass substrate and the dye film. Pure or V2O5 modified ITO substrates result in highly crystalline HB364 films where the dye molecules adopt an edge-on orientation. Changing the transition metal oxide layer to WO3 or MoO3 results in a less ordered dye film with a mixed growth of edge-on and face-on orientations. Planar HB364/C60 heterojunction (PHJ) solar cells are fabricated using the different transition metal oxides as the anode buffer layers. The devices with a pure ITO or a V2O5 modified anode demonstrate the highest power conversion efficiencies up to 2.7% that also outperform HB364:C60 bulk heterojunction (BHJ) devices (2.5%). Finally, HB364/HB364:C60 hybrid heterojunction (HHJ) cells are fabricated showing the highest power conversion efficiency of 2.9%.

  @article{C2JM14927C, abstract = {The growth of a thermally deposited merocyanine (HB364) thin film can be modified through insertion of a transition metal oxide layer between an indium tin oxide (ITO) covered glass substrate and the dye film. Pure or V2O5 modified ITO substrates result in highly crystalline HB364 films where the dye molecules adopt an edge-on orientation. Changing the transition metal oxide layer to WO3 or MoO3 results in a less ordered dye film with a mixed growth of edge-on and face-on orientations. Planar HB364/C60 heterojunction (PHJ) solar cells are fabricated using the different transition metal oxides as the anode buffer layers. The devices with a pure ITO or a V2O5 modified anode demonstrate the highest power conversion efficiencies up to 2.7% that also outperform HB364:C60 bulk heterojunction (BHJ) devices (2.5%). Finally{,} HB364/HB364:C60 hybrid heterojunction (HHJ) cells are fabricated showing the highest power conversion efficiency of 2.9%.}, author = {Ojala, Antti and Burckstummer, Hannah and Hwang, Jaehyung and Graf, Katja and von Vacano, Bernhard and Meerholz, Klaus and Erk, Peter and Würthner, Frank}, journal = {J. Mater. Chem.}, keywords = {myown}, number = 10, pages = {4473-4482}, publisher = {The Royal Society of Chemistry}, title = {Planar, bulk and hybrid merocyanine/C60 heterojunction devices: a case study on thin film morphology and photovoltaic performance}, volume = 22, year = 2012 }

  %0 Journal Article %1 C2JM14927C %A Ojala, Antti %A Burckstummer, Hannah %A Hwang, Jaehyung %A Graf, Katja %A von Vacano, Bernhard %A Meerholz, Klaus %A Erk, Peter %A Würthner, Frank %D 2012 %I The Royal Society of Chemistry %J J. Mater. Chem. %N 10 %P 4473-4482 %R 10.1039/C2JM14927C %T Planar, bulk and hybrid merocyanine/C60 heterojunction devices: a case study on thin film morphology and photovoltaic performance %U http://dx.doi.org/10.1039/C2JM14927C %V 22 %X The growth of a thermally deposited merocyanine (HB364) thin film can be modified through insertion of a transition metal oxide layer between an indium tin oxide (ITO) covered glass substrate and the dye film. Pure or V2O5 modified ITO substrates result in highly crystalline HB364 films where the dye molecules adopt an edge-on orientation. Changing the transition metal oxide layer to WO3 or MoO3 results in a less ordered dye film with a mixed growth of edge-on and face-on orientations. Planar HB364/C60 heterojunction (PHJ) solar cells are fabricated using the different transition metal oxides as the anode buffer layers. The devices with a pure ITO or a V2O5 modified anode demonstrate the highest power conversion efficiencies up to 2.7% that also outperform HB364:C60 bulk heterojunction (BHJ) devices (2.5%). Finally, HB364/HB364:C60 hybrid heterojunction (HHJ) cells are fabricated showing the highest power conversion efficiency of 2.9%.
• Covalently stabilized self-assembled chlorophyll nanorods by olefin metathesis. Sengupta, Sanchita; Würthner, Frank. In Chem. Commun., 48(46), pp. 5730–5732. 2012.
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  A new chlorophyll derivative with peripheral olefinic chains has been synthesised and its self-assembly properties have been studied, revealing formation of well-defined nanorods. These nanorods were stabilized and rigidified by olefin metathesis reaction as confirmed by spectroscopic and microscopic methods.

  @article{C2CC32314A, abstract = {A new chlorophyll derivative with peripheral olefinic chains has been synthesised and its self-assembly properties have been studied{,} revealing formation of well-defined nanorods. These nanorods were stabilized and rigidified by olefin metathesis reaction as confirmed by spectroscopic and microscopic methods.}, author = {Sengupta, Sanchita and Würthner, Frank}, journal = {Chem. Commun.}, keywords = {myown}, number = 46, pages = {5730-5732}, publisher = {The Royal Society of Chemistry}, title = {Covalently stabilized self-assembled chlorophyll nanorods by olefin metathesis}, volume = 48, year = 2012 }

  %0 Journal Article %1 C2CC32314A %A Sengupta, Sanchita %A Würthner, Frank %D 2012 %I The Royal Society of Chemistry %J Chem. Commun. %N 46 %P 5730-5732 %R 10.1039/C2CC32314A %T Covalently stabilized self-assembled chlorophyll nanorods by olefin metathesis %U http://dx.doi.org/10.1039/C2CC32314A %V 48 %X A new chlorophyll derivative with peripheral olefinic chains has been synthesised and its self-assembly properties have been studied, revealing formation of well-defined nanorods. These nanorods were stabilized and rigidified by olefin metathesis reaction as confirmed by spectroscopic and microscopic methods.
• Synthesis and Properties of a Covalently Linked Angular Perylene Imide Dimer. Thorley, Karl J.; Würthner, Frank. In Organic Letters, 14(24), pp. 6190–6193. 2012.

  PMID: 23163900
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  Utilizing the unexplored chemistry of a monocarbon analog to perylene bisimide, a covalently linked angular perylene dimer was synthesized. On the basis of measured optical properties and molecular modeling, the spectral changes relative to a monomeric reference perylene can be explained by an angle-dependent oblique exciton coupling model. With a roughly trigonal interchromophore arrangement, the dimer building block is promising for larger, cyclic assemblies to mimic naturally occurring light harvesting complexes.

  @article{doi:10.1021/ol3029115, abstract = {Utilizing the unexplored chemistry of a monocarbon analog to perylene bisimide, a covalently linked angular perylene dimer was synthesized. On the basis of measured optical properties and molecular modeling, the spectral changes relative to a monomeric reference perylene can be explained by an angle-dependent oblique exciton coupling model. With a roughly trigonal interchromophore arrangement, the dimer building block is promising for larger, cyclic assemblies to mimic naturally occurring light harvesting complexes.}, author = {Thorley, Karl J. and Würthner, Frank}, journal = {Organic Letters}, keywords = {myown}, note = {PMID: 23163900}, number = 24, pages = {6190-6193}, title = {Synthesis and Properties of a Covalently Linked Angular Perylene Imide Dimer}, volume = 14, year = 2012 }

  %0 Journal Article %1 doi:10.1021/ol3029115 %A Thorley, Karl J. %A Würthner, Frank %D 2012 %J Organic Letters %N 24 %P 6190-6193 %R 10.1021/ol3029115 %T Synthesis and Properties of a Covalently Linked Angular Perylene Imide Dimer %U http://dx.doi.org/10.1021/ol3029115 %V 14 %X Utilizing the unexplored chemistry of a monocarbon analog to perylene bisimide, a covalently linked angular perylene dimer was synthesized. On the basis of measured optical properties and molecular modeling, the spectral changes relative to a monomeric reference perylene can be explained by an angle-dependent oblique exciton coupling model. With a roughly trigonal interchromophore arrangement, the dimer building block is promising for larger, cyclic assemblies to mimic naturally occurring light harvesting complexes.
• Bay-substituted perylene bisimide dye with an undistorted planar scaffold and outstanding solid state fluorescence properties. Lin, Mei-Jin; Jimenez, Angel J.; Burschka, Christian; Würthner, Frank. In Chem. Commun., 48(99), pp. 12050–12052. 2012.
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  Single crystal X-ray analysis reveals a flat perylene [small pi]-scaffold for a perylene bisimide bearing bulky 2,6-diphenylphenoxy substituents at the 1,7 bay positions. The flat structure provides sharp vibronic progressions in the absorption and fluorescence spectra, the sterical shielding outstanding fluorescence quantum yields in the solid state.

  @article{C2CC36719J, abstract = {Single crystal X-ray analysis reveals a flat perylene [small pi]-scaffold for a perylene bisimide bearing bulky 2{,}6-diphenylphenoxy substituents at the 1{,}7 bay positions. The flat structure provides sharp vibronic progressions in the absorption and fluorescence spectra{,} the sterical shielding outstanding fluorescence quantum yields in the solid state.}, author = {Lin, Mei-Jin and Jimenez, Angel J. and Burschka, Christian and Würthner, Frank}, journal = {Chem. Commun.}, keywords = {myown}, number = 99, pages = {12050-12052}, publisher = {The Royal Society of Chemistry}, title = {Bay-substituted perylene bisimide dye with an undistorted planar scaffold and outstanding solid state fluorescence properties}, volume = 48, year = 2012 }

  %0 Journal Article %1 C2CC36719J %A Lin, Mei-Jin %A Jimenez, Angel J. %A Burschka, Christian %A Würthner, Frank %D 2012 %I The Royal Society of Chemistry %J Chem. Commun. %N 99 %P 12050-12052 %R 10.1039/C2CC36719J %T Bay-substituted perylene bisimide dye with an undistorted planar scaffold and outstanding solid state fluorescence properties %U http://dx.doi.org/10.1039/C2CC36719J %V 48 %X Single crystal X-ray analysis reveals a flat perylene [small pi]-scaffold for a perylene bisimide bearing bulky 2,6-diphenylphenoxy substituents at the 1,7 bay positions. The flat structure provides sharp vibronic progressions in the absorption and fluorescence spectra, the sterical shielding outstanding fluorescence quantum yields in the solid state.
• J-Aggregates of Perylene Dyes. Würthner, Frank; Scheblykin, I. G. Vol. 2, T. Kobayashi (ed.), pp. 309–342. 2012.
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  @inbook{wurthner2012jaggregates, author = {Würthner, Frank and Scheblykin, I. G.}, editor = {Kobayashi, T.}, keywords = {myown}, pages = {309–342}, title = {J-Aggregates of Perylene Dyes}, volume = 2, year = 2012 }

  %0 Book Section %1 wurthner2012jaggregates %A Würthner, Frank %A Scheblykin, I. G. %D 2012 %E Kobayashi, T. %P 309–342 %T J-Aggregates of Perylene Dyes %V 2
• Aggregation-dependent photovoltaic properties of squaraine/PC61BM bulk heterojunctions. Deing, Kaja C.; Mayerhoffer, Ulrich; Würthner, Frank; Meerholz, Klaus. In Phys. Chem. Chem. Phys., 14(23), pp. 8328–8334. 2012.
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  In this study, we investigated bulk-heterojunction solar cells composed of PC61BM and squaraine dyes with different donor subunits. Both, H- and J-aggregates, have been observed for the squaraine dyes in the mixture, even for the same dye depending on the annealing conditions of the blends. Supramolecular organization of the squaraine dyes noticeably affects solar cell performance. The J-aggregate exhibits a red-shift of the absorption maximum that results in a significant increase in the short-circuit current and decrease in the open-circuit voltage compared to the as-cast device. The H-aggregate shows a blue-shift in the absorption maximum and concomitantly only a moderate increase in the short-circuit current as well as an increase in the open-circuit voltage. The course of domain growth during annealing was monitored by local photocurrent mapping.

  @article{C2CP40789B, abstract = {In this study{,} we investigated bulk-heterojunction solar cells composed of PC61BM and squaraine dyes with different donor subunits. Both{,} H- and J-aggregates{,} have been observed for the squaraine dyes in the mixture{,} even for the same dye depending on the annealing conditions of the blends. Supramolecular organization of the squaraine dyes noticeably affects solar cell performance. The J-aggregate exhibits a red-shift of the absorption maximum that results in a significant increase in the short-circuit current and decrease in the open-circuit voltage compared to the as-cast device. The H-aggregate shows a blue-shift in the absorption maximum and concomitantly only a moderate increase in the short-circuit current as well as an increase in the open-circuit voltage. The course of domain growth during annealing was monitored by local photocurrent mapping.}, author = {Deing, Kaja C. and Mayerhoffer, Ulrich and Würthner, Frank and Meerholz, Klaus}, journal = {Phys. Chem. Chem. Phys.}, keywords = {myown}, number = 23, pages = {8328-8334}, publisher = {The Royal Society of Chemistry}, title = {Aggregation-dependent photovoltaic properties of squaraine/PC61BM bulk heterojunctions}, volume = 14, year = 2012 }

  %0 Journal Article %1 C2CP40789B %A Deing, Kaja C. %A Mayerhoffer, Ulrich %A Würthner, Frank %A Meerholz, Klaus %D 2012 %I The Royal Society of Chemistry %J Phys. Chem. Chem. Phys. %N 23 %P 8328-8334 %R 10.1039/C2CP40789B %T Aggregation-dependent photovoltaic properties of squaraine/PC61BM bulk heterojunctions %U http://dx.doi.org/10.1039/C2CP40789B %V 14 %X In this study, we investigated bulk-heterojunction solar cells composed of PC61BM and squaraine dyes with different donor subunits. Both, H- and J-aggregates, have been observed for the squaraine dyes in the mixture, even for the same dye depending on the annealing conditions of the blends. Supramolecular organization of the squaraine dyes noticeably affects solar cell performance. The J-aggregate exhibits a red-shift of the absorption maximum that results in a significant increase in the short-circuit current and decrease in the open-circuit voltage compared to the as-cast device. The H-aggregate shows a blue-shift in the absorption maximum and concomitantly only a moderate increase in the short-circuit current as well as an increase in the open-circuit voltage. The course of domain growth during annealing was monitored by local photocurrent mapping.
• Halogen–Arene Interactions Assist in Self-Assembly of Dyes. Mayerhöffer, Ulrich; Würthner, Frank. In Angew. Chem. Int. Ed., 51(23), pp. 5615–5619. 2012.
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  @article{ANIE:ANIE201200897, author = {Mayerhöffer, Ulrich and Würthner, Frank}, journal = {Angew. Chem. Int. Ed.}, keywords = {myown}, number = 23, pages = {5615–5619}, publisher = {WILEY-VCH Verlag}, title = {Halogen–Arene Interactions Assist in Self-Assembly of Dyes}, volume = 51, year = 2012 }

  %0 Journal Article %1 ANIE:ANIE201200897 %A Mayerhöffer, Ulrich %A Würthner, Frank %D 2012 %I WILEY-VCH Verlag %J Angew. Chem. Int. Ed. %N 23 %P 5615--5619 %R 10.1002/anie.201200897 %T Halogen–Arene Interactions Assist in Self-Assembly of Dyes %U http://dx.doi.org/10.1002/anie.201200897 %V 51
• Field-dependent exciton dissociation in organic heterojunction solar cells. Petersen, Andreas; Ojala, Antti; Kirchartz, Thomas; Wagner, Thomas A.; Würthner, Frank; Rau, Uwe. In Phys. Rev. B, 85(24), p. 245208. 2012.
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  @article{PhysRevB.85.245208, author = {Petersen, Andreas and Ojala, Antti and Kirchartz, Thomas and Wagner, Thomas A. and Würthner, Frank and Rau, Uwe}, journal = {Phys. Rev. B}, keywords = {myown}, month = {06}, number = 24, pages = 245208, publisher = {American Physical Society}, title = {Field-dependent exciton dissociation in organic heterojunction solar cells}, volume = 85, year = 2012 }

  %0 Journal Article %1 PhysRevB.85.245208 %A Petersen, Andreas %A Ojala, Antti %A Kirchartz, Thomas %A Wagner, Thomas A. %A Würthner, Frank %A Rau, Uwe %D 2012 %I American Physical Society %J Phys. Rev. B %N 24 %P 245208 %R 10.1103/PhysRevB.85.245208 %T Field-dependent exciton dissociation in organic heterojunction solar cells %U https://link.aps.org/doi/10.1103/PhysRevB.85.245208 %V 85
• Nondestructive Photoluminescence Read-Out by Intramolecular Electron Transfer in a Perylene Bisimide-Diarylethene Dyad. Berberich, Martin; Natali, Mirco; Spenst, Peter; Chiorboli, Claudio; Scandola, Franco; Würthner, Frank. In Chemistry – A European Journal, 18(43), pp. 13651–13664. 2012.
  • [ Abstract ]
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  A novel, highly stable photochromic dyad 3 based on a perylene bisimide (PBI) fluorophore and a diarylethene (DAE) photochrome was synthesized and the optical and photophysical properties of this dyad were studied in detail by steady-state and time-resolved ultrafast spectroscopy. This photochromic dyad can be switched reversibly by UV-light irradiation of its ring-open form 3 o leading to the ring-closed form 3 c, and back reaction of 3 c to 3 o by irradiation with visible light. Solvent-dependent fluorescence studies revealed that the emission of ring-closed form 3 c is drastically quenched in solvents of medium (e.g., chloroform) to high (e.g., acetone) polarities, while the emission of the ring-open form 3 o is appreciably quenched only in highly polar solvents like DMF. The strong fluorescence quenching of 3 c is attributed to a photoinduced electron-transfer (PET) process from the excited PBI unit to ring-closed DAE moiety, as this process is thermodynamically highly favorable with a Gibbs free energy value of −0.34 eV in dichloromethane. The electron-transfer mechanism for the fluorescence quenching of ring-closed 3 c is substantiated by ultrafast transient measurements in dichloromethane and acetone, revealing stabilization of charge-separated states of 3 c in these solvents. Our results reported here show that the new photochromic dyad 3 has potential for nondestructive read-out in write/read/erase fluorescent memory systems.

  @article{CHEM:CHEM201201484, abstract = {A novel, highly stable photochromic dyad 3 based on a perylene bisimide (PBI) fluorophore and a diarylethene (DAE) photochrome was synthesized and the optical and photophysical properties of this dyad were studied in detail by steady-state and time-resolved ultrafast spectroscopy. This photochromic dyad can be switched reversibly by UV-light irradiation of its ring-open form 3 o leading to the ring-closed form 3 c, and back reaction of 3 c to 3 o by irradiation with visible light. Solvent-dependent fluorescence studies revealed that the emission of ring-closed form 3 c is drastically quenched in solvents of medium (e.g., chloroform) to high (e.g., acetone) polarities, while the emission of the ring-open form 3 o is appreciably quenched only in highly polar solvents like DMF. The strong fluorescence quenching of 3 c is attributed to a photoinduced electron-transfer (PET) process from the excited PBI unit to ring-closed DAE moiety, as this process is thermodynamically highly favorable with a Gibbs free energy value of −0.34 eV in dichloromethane. The electron-transfer mechanism for the fluorescence quenching of ring-closed 3 c is substantiated by ultrafast transient measurements in dichloromethane and acetone, revealing stabilization of charge-separated states of 3 c in these solvents. Our results reported here show that the new photochromic dyad 3 has potential for nondestructive read-out in write/read/erase fluorescent memory systems.}, author = {Berberich, Martin and Natali, Mirco and Spenst, Peter and Chiorboli, Claudio and Scandola, Franco and Würthner, Frank}, journal = {Chemistry – A European Journal}, keywords = {myown}, number = 43, pages = {13651–13664}, publisher = {WILEY-VCH Verlag}, title = {Nondestructive Photoluminescence Read-Out by Intramolecular Electron Transfer in a Perylene Bisimide-Diarylethene Dyad}, volume = 18, year = 2012 }

  %0 Journal Article %1 CHEM:CHEM201201484 %A Berberich, Martin %A Natali, Mirco %A Spenst, Peter %A Chiorboli, Claudio %A Scandola, Franco %A Würthner, Frank %D 2012 %I WILEY-VCH Verlag %J Chemistry – A European Journal %N 43 %P 13651--13664 %R 10.1002/chem.201201484 %T Nondestructive Photoluminescence Read-Out by Intramolecular Electron Transfer in a Perylene Bisimide-Diarylethene Dyad %U http://dx.doi.org/10.1002/chem.201201484 %V 18 %X A novel, highly stable photochromic dyad 3 based on a perylene bisimide (PBI) fluorophore and a diarylethene (DAE) photochrome was synthesized and the optical and photophysical properties of this dyad were studied in detail by steady-state and time-resolved ultrafast spectroscopy. This photochromic dyad can be switched reversibly by UV-light irradiation of its ring-open form 3 o leading to the ring-closed form 3 c, and back reaction of 3 c to 3 o by irradiation with visible light. Solvent-dependent fluorescence studies revealed that the emission of ring-closed form 3 c is drastically quenched in solvents of medium (e.g., chloroform) to high (e.g., acetone) polarities, while the emission of the ring-open form 3 o is appreciably quenched only in highly polar solvents like DMF. The strong fluorescence quenching of 3 c is attributed to a photoinduced electron-transfer (PET) process from the excited PBI unit to ring-closed DAE moiety, as this process is thermodynamically highly favorable with a Gibbs free energy value of −0.34 eV in dichloromethane. The electron-transfer mechanism for the fluorescence quenching of ring-closed 3 c is substantiated by ultrafast transient measurements in dichloromethane and acetone, revealing stabilization of charge-separated states of 3 c in these solvents. Our results reported here show that the new photochromic dyad 3 has potential for nondestructive read-out in write/read/erase fluorescent memory systems.
• Single molecule studies of calix4arene-linked perylene bisimide dimers: relationship between blinking, lifetime and/or spectral fluctuations. Issac, Abey; Hildner, Richard; Ernst, Dominique; Hippius, Catharina; Würthner, Frank; Kohler, Jurgen. In Phys. Chem. Chem. Phys., 14(30), pp. 10789–10798. 2012.
  • [ Abstract ]
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  We recorded fluorescence time traces, and simultaneously either the fluorescence lifetime or the emission spectra from single perylene bisimide (PBI) dimers embedded in a polystyrene matrix. In these traces three distinct intensity levels can be distinguished, which reflect the photo-induced radicalisation of one of the perylene subunits. Differences in the energy transfer rate between the neutral PBI and the reversibly formed radical anion give rise to variations in the chronological order of the appearance of the intensity levels, which allowed us to categorise the time traces into three distinct groups: Type 1 blinking corresponds to a high energy transfer rate, type 2 blinking to fluctuations between large and small transfer rates (dynamic quenching), and type 3 blinking results from small energy transfer rates together with Coulomb blockade. The information that we obtain from the distributions of the fluorescence lifetimes at the various signal levels allows us to relate these differences to properties of the local polymer environment of the dimers.

  @article{C2CP41250K, abstract = {We recorded fluorescence time traces{,} and simultaneously either the fluorescence lifetime or the emission spectra from single perylene bisimide (PBI) dimers embedded in a polystyrene matrix. In these traces three distinct intensity levels can be distinguished{,} which reflect the photo-induced radicalisation of one of the perylene subunits. Differences in the energy transfer rate between the neutral PBI and the reversibly formed radical anion give rise to variations in the chronological order of the appearance of the intensity levels{,} which allowed us to categorise the time traces into three distinct groups: Type 1 blinking corresponds to a high energy transfer rate{,} type 2 blinking to fluctuations between large and small transfer rates (dynamic quenching){,} and type 3 blinking results from small energy transfer rates together with Coulomb blockade. The information that we obtain from the distributions of the fluorescence lifetimes at the various signal levels allows us to relate these differences to properties of the local polymer environment of the dimers.}, author = {Issac, Abey and Hildner, Richard and Ernst, Dominique and Hippius, Catharina and Würthner, Frank and Kohler, Jurgen}, journal = {Phys. Chem. Chem. Phys.}, keywords = {myown}, number = 30, pages = {10789-10798}, publisher = {The Royal Society of Chemistry}, title = {Single molecule studies of calix4arene-linked perylene bisimide dimers: relationship between blinking, lifetime and/or spectral fluctuations}, volume = 14, year = 2012 }

  %0 Journal Article %1 C2CP41250K %A Issac, Abey %A Hildner, Richard %A Ernst, Dominique %A Hippius, Catharina %A Würthner, Frank %A Kohler, Jurgen %D 2012 %I The Royal Society of Chemistry %J Phys. Chem. Chem. Phys. %N 30 %P 10789-10798 %R 10.1039/C2CP41250K %T Single molecule studies of calix4arene-linked perylene bisimide dimers: relationship between blinking, lifetime and/or spectral fluctuations %U http://dx.doi.org/10.1039/C2CP41250K %V 14 %X We recorded fluorescence time traces, and simultaneously either the fluorescence lifetime or the emission spectra from single perylene bisimide (PBI) dimers embedded in a polystyrene matrix. In these traces three distinct intensity levels can be distinguished, which reflect the photo-induced radicalisation of one of the perylene subunits. Differences in the energy transfer rate between the neutral PBI and the reversibly formed radical anion give rise to variations in the chronological order of the appearance of the intensity levels, which allowed us to categorise the time traces into three distinct groups: Type 1 blinking corresponds to a high energy transfer rate, type 2 blinking to fluctuations between large and small transfer rates (dynamic quenching), and type 3 blinking results from small energy transfer rates together with Coulomb blockade. The information that we obtain from the distributions of the fluorescence lifetimes at the various signal levels allows us to relate these differences to properties of the local polymer environment of the dimers.
• Chiral J-Aggregates of Atropo-Enantiomeric Perylene Bisimides and Their Self-Sorting Behavior. Xie, Zengqi; Stepanenko, Vladimir; Radacki, Krzysztof; Würthner, Frank. In Chemistry – A European Journal, 18(23), pp. 7060–7070. 2012.
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  Herein we report on structural, morphological, and optical properties of homochiral and heterochiral J-aggregates that were created by nucleation–elongation assembly of atropo-enantiomerically pure and racemic perylene bisimides (PBIs), respectively. Our detailed studies with conformationally stable biphenoxy-bridged chiral PBIs by UV/Vis absorption, circular dichroism (CD) spectroscopy, and atomic force microscopy (AFM) revealed structurally as well as spectroscopically quite different kinds of J-aggregates for enantiomerically pure and racemic PBIs. AFM investigations showed that enantiopure PBIs form helical nanowires of unique diameter and large length-to-width ratio by self-recognition, while racemic PBIs provide irregular-sized particles by self-discrimination of the enantiomers at the stage of nucleation. Steady-state fluorescence spectroscopy studies revealed that the photoluminescence efficiency of homochiral J-aggregated nanowires (47±3 %) is significantly higher than that of heterochiral J-aggregated particle-like aggregates (12±3 %), which is explained in terms of highly ordered molecular stacking in one-dimensional nanowires of homochiral J-aggregates. Our present results demonstrate the high impact of homochirality on the construction of well-defined nanostructures with unique optical properties.

  @article{CHEM:CHEM201200089, abstract = {Herein we report on structural, morphological, and optical properties of homochiral and heterochiral J-aggregates that were created by nucleation–elongation assembly of atropo-enantiomerically pure and racemic perylene bisimides (PBIs), respectively. Our detailed studies with conformationally stable biphenoxy-bridged chiral PBIs by UV/Vis absorption, circular dichroism (CD) spectroscopy, and atomic force microscopy (AFM) revealed structurally as well as spectroscopically quite different kinds of J-aggregates for enantiomerically pure and racemic PBIs. AFM investigations showed that enantiopure PBIs form helical nanowires of unique diameter and large length-to-width ratio by self-recognition, while racemic PBIs provide irregular-sized particles by self-discrimination of the enantiomers at the stage of nucleation. Steady-state fluorescence spectroscopy studies revealed that the photoluminescence efficiency of homochiral J-aggregated nanowires (47±3 %) is significantly higher than that of heterochiral J-aggregated particle-like aggregates (12±3 %), which is explained in terms of highly ordered molecular stacking in one-dimensional nanowires of homochiral J-aggregates. Our present results demonstrate the high impact of homochirality on the construction of well-defined nanostructures with unique optical properties.}, author = {Xie, Zengqi and Stepanenko, Vladimir and Radacki, Krzysztof and Würthner, Frank}, journal = {Chemistry – A European Journal}, keywords = {myown}, number = 23, pages = {7060–7070}, publisher = {WILEY-VCH Verlag}, title = {Chiral J-Aggregates of Atropo-Enantiomeric Perylene Bisimides and Their Self-Sorting Behavior}, volume = 18, year = 2012 }

  %0 Journal Article %1 CHEM:CHEM201200089 %A Xie, Zengqi %A Stepanenko, Vladimir %A Radacki, Krzysztof %A Würthner, Frank %D 2012 %I WILEY-VCH Verlag %J Chemistry – A European Journal %N 23 %P 7060--7070 %R 10.1002/chem.201200089 %T Chiral J-Aggregates of Atropo-Enantiomeric Perylene Bisimides and Their Self-Sorting Behavior %U http://dx.doi.org/10.1002/chem.201200089 %V 18 %X Herein we report on structural, morphological, and optical properties of homochiral and heterochiral J-aggregates that were created by nucleation–elongation assembly of atropo-enantiomerically pure and racemic perylene bisimides (PBIs), respectively. Our detailed studies with conformationally stable biphenoxy-bridged chiral PBIs by UV/Vis absorption, circular dichroism (CD) spectroscopy, and atomic force microscopy (AFM) revealed structurally as well as spectroscopically quite different kinds of J-aggregates for enantiomerically pure and racemic PBIs. AFM investigations showed that enantiopure PBIs form helical nanowires of unique diameter and large length-to-width ratio by self-recognition, while racemic PBIs provide irregular-sized particles by self-discrimination of the enantiomers at the stage of nucleation. Steady-state fluorescence spectroscopy studies revealed that the photoluminescence efficiency of homochiral J-aggregated nanowires (47±3 %) is significantly higher than that of heterochiral J-aggregated particle-like aggregates (12±3 %), which is explained in terms of highly ordered molecular stacking in one-dimensional nanowires of homochiral J-aggregates. Our present results demonstrate the high impact of homochirality on the construction of well-defined nanostructures with unique optical properties.
• Excitation energy migration in covalently linked perylene bisimide macrocycles. Schlosser, Felix; Sung, Jooyoung; Kim, Pyosang; Kim, Dongho; Würthner, Frank. In Chem. Sci., 3(9), pp. 2778–2785. 2012.
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  A series of acetylene-linked perylene bisimide (PBI) macrocycles 3a-d with various ring sizes from trimer to hexamer have been synthesised by a palladium-catalysed homocoupling reaction of perylene bisimide 1. Photophysical properties of these PBI macrocycles have been examined by steady-state absorption, fluorescence, fluorescence lifetime, fluorescence anisotropy decay, and transient absorption measurements. Both pump-power dependence on the femtosecond transient absorption and the transient absorption anisotropy decay profiles are directly related with the excitation energy migration processes within PBI macrocycles where the exciton-exciton annihilation time and the polarization anisotropy decay time are well described in terms of the Forster-type incoherent energy hopping model. Consequently, the excitation energy hopping times of macrocycles become slower and then saturated as the ring size increases. Nevertheless, the intrinsically large transition dipole moment of PBI leads to fast energy transfer processes as compared to other artificial light-harvesting complexes such as those constructed from porphyrin building blocks.

  @article{C2SC20589K, abstract = {A series of acetylene-linked perylene bisimide (PBI) macrocycles 3a-d with various ring sizes from trimer to hexamer have been synthesised by a palladium-catalysed homocoupling reaction of perylene bisimide 1. Photophysical properties of these PBI macrocycles have been examined by steady-state absorption{,} fluorescence{,} fluorescence lifetime{,} fluorescence anisotropy decay{,} and transient absorption measurements. Both pump-power dependence on the femtosecond transient absorption and the transient absorption anisotropy decay profiles are directly related with the excitation energy migration processes within PBI macrocycles where the exciton-exciton annihilation time and the polarization anisotropy decay time are well described in terms of the Forster-type incoherent energy hopping model. Consequently{,} the excitation energy hopping times of macrocycles become slower and then saturated as the ring size increases. Nevertheless{,} the intrinsically large transition dipole moment of PBI leads to fast energy transfer processes as compared to other artificial light-harvesting complexes such as those constructed from porphyrin building blocks.}, author = {Schlosser, Felix and Sung, Jooyoung and Kim, Pyosang and Kim, Dongho and Würthner, Frank}, journal = {Chem. Sci.}, keywords = {myown}, number = 9, pages = {2778-2785}, publisher = {The Royal Society of Chemistry}, title = {Excitation energy migration in covalently linked perylene bisimide macrocycles}, volume = 3, year = 2012 }

  %0 Journal Article %1 C2SC20589K %A Schlosser, Felix %A Sung, Jooyoung %A Kim, Pyosang %A Kim, Dongho %A Würthner, Frank %D 2012 %I The Royal Society of Chemistry %J Chem. Sci. %N 9 %P 2778-2785 %R 10.1039/C2SC20589K %T Excitation energy migration in covalently linked perylene bisimide macrocycles %U http://dx.doi.org/10.1039/C2SC20589K %V 3 %X A series of acetylene-linked perylene bisimide (PBI) macrocycles 3a-d with various ring sizes from trimer to hexamer have been synthesised by a palladium-catalysed homocoupling reaction of perylene bisimide 1. Photophysical properties of these PBI macrocycles have been examined by steady-state absorption, fluorescence, fluorescence lifetime, fluorescence anisotropy decay, and transient absorption measurements. Both pump-power dependence on the femtosecond transient absorption and the transient absorption anisotropy decay profiles are directly related with the excitation energy migration processes within PBI macrocycles where the exciton-exciton annihilation time and the polarization anisotropy decay time are well described in terms of the Forster-type incoherent energy hopping model. Consequently, the excitation energy hopping times of macrocycles become slower and then saturated as the ring size increases. Nevertheless, the intrinsically large transition dipole moment of PBI leads to fast energy transfer processes as compared to other artificial light-harvesting complexes such as those constructed from porphyrin building blocks.
• Cooperative self-assembly of squaraine dyes. Mayerhoffer, Ulrich; Würthner, Frank. In Chem. Sci., 3(4), pp. 1215–1220. 2012.
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  A novel, highly soluble squaraine dye was synthesised in organic solvents by condensation of squaric acid with an appropriately functionalised donor unit and the aggregation behaviour of this squaraine in organic solvents was investigated in detail by concentration- and temperature-dependent UV/vis spectroscopy. The absorption band of this squaraine dye exhibits a hypsochromic shift of more than 100 nm upon aggregation, indicating a H-type excitonic coupling in aggregates. Our detailed studies reveal a cooperative aggregation process with K2 = 4.87 +/- 0.13 [times] 104 M-1 for the dimerization and an elongation constant of K = 4.87 +/- 0.13 [times] 105 M-1 according to the K2/K model. The thermodynamics of this process were investigated by applying Meijer's model of nucleation-elongation growth, which provided an elongation temperature of Te = 311 K with a molecular enthalpy release of he = -97 kJ mol-1 and a nucleus size of about two. Furthermore, the structural features of the aggregates were elucidated by AFM and spectroscopic methods, revealing the formation of extended supramolecular fibres.

  @article{C2SC00996J, abstract = {A novel{,} highly soluble squaraine dye was synthesised in organic solvents by condensation of squaric acid with an appropriately functionalised donor unit and the aggregation behaviour of this squaraine in organic solvents was investigated in detail by concentration- and temperature-dependent UV/vis spectroscopy. The absorption band of this squaraine dye exhibits a hypsochromic shift of more than 100 nm upon aggregation{,} indicating a H-type excitonic coupling in aggregates. Our detailed studies reveal a cooperative aggregation process with K2 = 4.87 +/- 0.13 [times] 104 M-1 for the dimerization and an elongation constant of K = 4.87 +/- 0.13 [times] 105 M-1 according to the K2/K model. The thermodynamics of this process were investigated by applying Meijer{'}s model of nucleation-elongation growth{,} which provided an elongation temperature of Te = 311 K with a molecular enthalpy release of he = -97 kJ mol-1 and a nucleus size of about two. Furthermore{,} the structural features of the aggregates were elucidated by AFM and spectroscopic methods{,} revealing the formation of extended supramolecular fibres.}, author = {Mayerhoffer, Ulrich and Würthner, Frank}, journal = {Chem. Sci.}, keywords = {myown}, number = 4, pages = {1215-1220}, publisher = {The Royal Society of Chemistry}, title = {Cooperative self-assembly of squaraine dyes}, volume = 3, year = 2012 }

  %0 Journal Article %1 C2SC00996J %A Mayerhoffer, Ulrich %A Würthner, Frank %D 2012 %I The Royal Society of Chemistry %J Chem. Sci. %N 4 %P 1215-1220 %R 10.1039/C2SC00996J %T Cooperative self-assembly of squaraine dyes %U http://dx.doi.org/10.1039/C2SC00996J %V 3 %X A novel, highly soluble squaraine dye was synthesised in organic solvents by condensation of squaric acid with an appropriately functionalised donor unit and the aggregation behaviour of this squaraine in organic solvents was investigated in detail by concentration- and temperature-dependent UV/vis spectroscopy. The absorption band of this squaraine dye exhibits a hypsochromic shift of more than 100 nm upon aggregation, indicating a H-type excitonic coupling in aggregates. Our detailed studies reveal a cooperative aggregation process with K2 = 4.87 +/- 0.13 [times] 104 M-1 for the dimerization and an elongation constant of K = 4.87 +/- 0.13 [times] 105 M-1 according to the K2/K model. The thermodynamics of this process were investigated by applying Meijer's model of nucleation-elongation growth, which provided an elongation temperature of Te = 311 K with a molecular enthalpy release of he = -97 kJ mol-1 and a nucleus size of about two. Furthermore, the structural features of the aggregates were elucidated by AFM and spectroscopic methods, revealing the formation of extended supramolecular fibres.
• Solvent and substituent effects on aggregation constants of perylene bisimide [small pi]-stacks - a linear free energy relationship analysis. Chen, Zhijian; Fimmel, Benjamin; Würthner, Frank. In Org. Biomol. Chem., 10(30), pp. 5845–5855. 2012.
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  A series of six perylene bisimides (PBIs) with hydrophilic and hydrophobic side chains at the imide nitrogens were applied for a comparative study of the solvent and structural effects on the aggregation behaviour of this class of dyes. A comparison of the binding constants in tetrachloromethane at room temperature revealed the highest binding constant of about 105 M-1 for a PBI bearing 3,4,5-tridodecyloxyphenyl substituents at the imide nitrogens, followed by 3,4,5-tridodecylphenyl and alkyl-substituted PBIs, whereas no aggregation could be observed in the accessible concentration range for PBIs equipped with bulky 2,6-diisopropylphenyl substituents at the imide nitrogens. The aggregation behaviour of three properly soluble compounds was investigated in 17 different solvents covering a broad polarity range from nonpolar n-hexane to highly polar DMSO and water. Linear free energy relationships (LFER) revealed a biphasic behaviour between Gibbs free energies of aggregation and common empirical solvent polarity scales indicating particularly strong [small pi]-[small pi] stacking interactions in nonpolar aliphatic and polar alcoholic solvents whilst the weakest binding is observed in dichloromethane and chloroform. Accordingly, PBI aggregation is dominated by electrostatic interactions in nonpolar solvents and by solvophobic interactions in protic solvents. In water, the aggregation constant is increased far beyond LFER expectations pointing at a pronounced hydrophobic effect.

  @article{C2OB07131B, abstract = {A series of six perylene bisimides (PBIs) with hydrophilic and hydrophobic side chains at the imide nitrogens were applied for a comparative study of the solvent and structural effects on the aggregation behaviour of this class of dyes. A comparison of the binding constants in tetrachloromethane at room temperature revealed the highest binding constant of about 105 M-1 for a PBI bearing 3{,}4{,}5-tridodecyloxyphenyl substituents at the imide nitrogens{,} followed by 3{,}4{,}5-tridodecylphenyl and alkyl-substituted PBIs{,} whereas no aggregation could be observed in the accessible concentration range for PBIs equipped with bulky 2{,}6-diisopropylphenyl substituents at the imide nitrogens. The aggregation behaviour of three properly soluble compounds was investigated in 17 different solvents covering a broad polarity range from nonpolar n-hexane to highly polar DMSO and water. Linear free energy relationships (LFER) revealed a biphasic behaviour between Gibbs free energies of aggregation and common empirical solvent polarity scales indicating particularly strong [small pi]-[small pi] stacking interactions in nonpolar aliphatic and polar alcoholic solvents whilst the weakest binding is observed in dichloromethane and chloroform. Accordingly{,} PBI aggregation is dominated by electrostatic interactions in nonpolar solvents and by solvophobic interactions in protic solvents. In water{,} the aggregation constant is increased far beyond LFER expectations pointing at a pronounced hydrophobic effect.}, author = {Chen, Zhijian and Fimmel, Benjamin and Würthner, Frank}, journal = {Org. Biomol. Chem.}, keywords = {myown}, number = 30, pages = {5845-5855}, publisher = {The Royal Society of Chemistry}, title = {Solvent and substituent effects on aggregation constants of perylene bisimide [small pi]-stacks - a linear free energy relationship analysis}, volume = 10, year = 2012 }

  %0 Journal Article %1 C2OB07131B %A Chen, Zhijian %A Fimmel, Benjamin %A Würthner, Frank %D 2012 %I The Royal Society of Chemistry %J Org. Biomol. Chem. %N 30 %P 5845-5855 %R 10.1039/C2OB07131B %T Solvent and substituent effects on aggregation constants of perylene bisimide [small pi]-stacks - a linear free energy relationship analysis %U http://dx.doi.org/10.1039/C2OB07131B %V 10 %X A series of six perylene bisimides (PBIs) with hydrophilic and hydrophobic side chains at the imide nitrogens were applied for a comparative study of the solvent and structural effects on the aggregation behaviour of this class of dyes. A comparison of the binding constants in tetrachloromethane at room temperature revealed the highest binding constant of about 105 M-1 for a PBI bearing 3,4,5-tridodecyloxyphenyl substituents at the imide nitrogens, followed by 3,4,5-tridodecylphenyl and alkyl-substituted PBIs, whereas no aggregation could be observed in the accessible concentration range for PBIs equipped with bulky 2,6-diisopropylphenyl substituents at the imide nitrogens. The aggregation behaviour of three properly soluble compounds was investigated in 17 different solvents covering a broad polarity range from nonpolar n-hexane to highly polar DMSO and water. Linear free energy relationships (LFER) revealed a biphasic behaviour between Gibbs free energies of aggregation and common empirical solvent polarity scales indicating particularly strong [small pi]-[small pi] stacking interactions in nonpolar aliphatic and polar alcoholic solvents whilst the weakest binding is observed in dichloromethane and chloroform. Accordingly, PBI aggregation is dominated by electrostatic interactions in nonpolar solvents and by solvophobic interactions in protic solvents. In water, the aggregation constant is increased far beyond LFER expectations pointing at a pronounced hydrophobic effect.
• Bright Near-Infrared Fluorophores Based on Squaraines by Unexpected Halogen Effects. Mayerhöffer, Ulrich; Fimmel, Benjamin; Würthner, Frank. In Angew. Chem. Int. Ed., 51(1), pp. 164–167. 2012.
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  @article{ANGE:ANGE201107176, author = {Mayerhöffer, Ulrich and Fimmel, Benjamin and Würthner, Frank}, journal = {Angew. Chem. Int. Ed.}, keywords = {myown}, number = 1, pages = {164 - 167}, publisher = {WILEY-VCH Verlag}, title = {Bright Near-Infrared Fluorophores Based on Squaraines by Unexpected Halogen Effects}, volume = 51, year = 2012 }

  %0 Journal Article %1 ANGE:ANGE201107176 %A Mayerhöffer, Ulrich %A Fimmel, Benjamin %A Würthner, Frank %D 2012 %I WILEY-VCH Verlag %J Angew. Chem. Int. Ed. %N 1 %P 164 - 167 %R 10.1002/anie.201107176 %T Bright Near-Infrared Fluorophores Based on Squaraines by Unexpected Halogen Effects %U https://onlinelibrary.wiley.com/doi/full/10.1002/anie.201107176 %V 51
• Merocyanine/C60 Planar Heterojunction Solar Cells: Effect of Dye Orientation on Exciton Dissociation and Solar Cell Performance. Ojala, Antti; Petersen, Andreas; Fuchs, Andreas; Lovrincic, Robert; Pölking, Carl; Trollmann, Jens; Hwang, Jaehyung; Lennartz, Christian; Reichelt, Helmut; Höffken, Hans Wolfgang; Pucci, Annemarie; Erk, Peter; Kirchartz, Thomas; Würthner, Frank. In Advanced Functional Materials, 22(1), pp. 86–96. 2012.
  • [ Abstract ]
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  In this study the charge dissociation at the donor/acceptor heterointerface of thermally evaporated planar heterojunction merocyanine/C60 organic solar cells is investigated. Deposition of the donor material on a heated substrate as well as post-annealing of the complete devices at temperatures above the glass transition temperature of the donor material results in a twofold increase of the fill factor. An analytical model employing an electric-field-dependent exciton dissociation mechanism reveals that geminate recombination is limiting the performance of as-deposited cells. Fourier-transform infrared ellipsometry shows that, at temperatures above the glass transition temperature of the donor material, the orientation of the dye molecules in the donor films undergoes changes upon annealing. Based on this finding, the influence of the dye molecules’ orientations on the charge-transfer state energies is calculated by quantum mechanical/molecular mechanics methods. The results of these detailed studies provide new insight into the exciton dissociation process in organic photovoltaic devices, and thus valuable guidelines for designing new donor materials.

  @article{ADFM:ADFM201101697, abstract = {In this study the charge dissociation at the donor/acceptor heterointerface of thermally evaporated planar heterojunction merocyanine/C60 organic solar cells is investigated. Deposition of the donor material on a heated substrate as well as post-annealing of the complete devices at temperatures above the glass transition temperature of the donor material results in a twofold increase of the fill factor. An analytical model employing an electric-field-dependent exciton dissociation mechanism reveals that geminate recombination is limiting the performance of as-deposited cells. Fourier-transform infrared ellipsometry shows that, at temperatures above the glass transition temperature of the donor material, the orientation of the dye molecules in the donor films undergoes changes upon annealing. Based on this finding, the influence of the dye molecules’ orientations on the charge-transfer state energies is calculated by quantum mechanical/molecular mechanics methods. The results of these detailed studies provide new insight into the exciton dissociation process in organic photovoltaic devices, and thus valuable guidelines for designing new donor materials.}, author = {Ojala, Antti and Petersen, Andreas and Fuchs, Andreas and Lovrincic, Robert and Pölking, Carl and Trollmann, Jens and Hwang, Jaehyung and Lennartz, Christian and Reichelt, Helmut and Höffken, Hans Wolfgang and Pucci, Annemarie and Erk, Peter and Kirchartz, Thomas and Würthner, Frank}, journal = {Advanced Functional Materials}, keywords = {myown}, number = 1, pages = {86–96}, publisher = {WILEY-VCH Verlag}, title = {Merocyanine/C60 Planar Heterojunction Solar Cells: Effect of Dye Orientation on Exciton Dissociation and Solar Cell Performance}, volume = 22, year = 2012 }

  %0 Journal Article %1 ADFM:ADFM201101697 %A Ojala, Antti %A Petersen, Andreas %A Fuchs, Andreas %A Lovrincic, Robert %A Pölking, Carl %A Trollmann, Jens %A Hwang, Jaehyung %A Lennartz, Christian %A Reichelt, Helmut %A Höffken, Hans Wolfgang %A Pucci, Annemarie %A Erk, Peter %A Kirchartz, Thomas %A Würthner, Frank %D 2012 %I WILEY-VCH Verlag %J Advanced Functional Materials %N 1 %P 86--96 %R 10.1002/adfm.201101697 %T Merocyanine/C60 Planar Heterojunction Solar Cells: Effect of Dye Orientation on Exciton Dissociation and Solar Cell Performance %U http://dx.doi.org/10.1002/adfm.201101697 %V 22 %X In this study the charge dissociation at the donor/acceptor heterointerface of thermally evaporated planar heterojunction merocyanine/C60 organic solar cells is investigated. Deposition of the donor material on a heated substrate as well as post-annealing of the complete devices at temperatures above the glass transition temperature of the donor material results in a twofold increase of the fill factor. An analytical model employing an electric-field-dependent exciton dissociation mechanism reveals that geminate recombination is limiting the performance of as-deposited cells. Fourier-transform infrared ellipsometry shows that, at temperatures above the glass transition temperature of the donor material, the orientation of the dye molecules in the donor films undergoes changes upon annealing. Based on this finding, the influence of the dye molecules’ orientations on the charge-transfer state energies is calculated by quantum mechanical/molecular mechanics methods. The results of these detailed studies provide new insight into the exciton dissociation process in organic photovoltaic devices, and thus valuable guidelines for designing new donor materials.
• Biosupramolecular Nanowires from Chlorophyll Dyes with Exceptional Charge-Transport Properties. Sengupta, Sanchita; Ebeling, Daniel; Patwardhan, Sameer; Zhang, Xin; von Berlepsch, Hans; Böttcher, Christoph; Stepanenko, Vladimir; Uemura, Shinobu; Hentschel, Carsten; Fuchs, Harald; Grozema, Ferdinand C.; Siebbeles, Laurens D. A.; Holzwarth, Alfred R.; Chi, Lifeng; Würthner, Frank. In Angew. Chem. Int. Ed., 51(26), pp. 6378–6382. 2012.
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  @article{ANIE:ANIE201201961, author = {Sengupta, Sanchita and Ebeling, Daniel and Patwardhan, Sameer and Zhang, Xin and von Berlepsch, Hans and Böttcher, Christoph and Stepanenko, Vladimir and Uemura, Shinobu and Hentschel, Carsten and Fuchs, Harald and Grozema, Ferdinand C. and Siebbeles, Laurens D. A. and Holzwarth, Alfred R. and Chi, Lifeng and Würthner, Frank}, journal = {Angew. Chem. Int. Ed.}, keywords = {myown}, number = 26, pages = {6378–6382}, publisher = {WILEY-VCH Verlag}, title = {Biosupramolecular Nanowires from Chlorophyll Dyes with Exceptional Charge-Transport Properties}, volume = 51, year = 2012 }

  %0 Journal Article %1 ANIE:ANIE201201961 %A Sengupta, Sanchita %A Ebeling, Daniel %A Patwardhan, Sameer %A Zhang, Xin %A von Berlepsch, Hans %A Böttcher, Christoph %A Stepanenko, Vladimir %A Uemura, Shinobu %A Hentschel, Carsten %A Fuchs, Harald %A Grozema, Ferdinand C. %A Siebbeles, Laurens D. A. %A Holzwarth, Alfred R. %A Chi, Lifeng %A Würthner, Frank %D 2012 %I WILEY-VCH Verlag %J Angew. Chem. Int. Ed. %N 26 %P 6378--6382 %R 10.1002/anie.201201961 %T Biosupramolecular Nanowires from Chlorophyll Dyes with Exceptional Charge-Transport Properties %U http://dx.doi.org/10.1002/anie.201201961 %V 51
• Size-dependent exciton dynamics in one-dimensional perylene bisimide aggregates. Wolter, Steffen; Aizezers, Janis; Fennel, Franziska; Seidel, Marcus; Würthner, Frank; Kühn, Oliver; Lochbrunner, Stefan. In New Journal of Physics, 14(10), p. 105027. 2012.
  • [ Abstract ]
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  The size-dependent exciton dynamics of one-dimensional aggregates of substituted perylene bisimides are studied by ultrafast transient absorption spectroscopy and kinetic Monte-Carlo simulations as a function of the excitation density and the temperature in the range of 25–90 °C. For low temperatures, the aggregates can be treated as infinite chains and the dynamics is dominated by diffusion-driven exciton–exciton annihilation. With increasing temperature the aggregates dissociate into small fragments consisting of very few monomers. This scenario is also supported by the time-dependent anisotropy deduced from polarization-dependent experiments.

  @article{1367-2630-14-10-105027, abstract = {The size-dependent exciton dynamics of one-dimensional aggregates of substituted perylene bisimides are studied by ultrafast transient absorption spectroscopy and kinetic Monte-Carlo simulations as a function of the excitation density and the temperature in the range of 25–90 °C. For low temperatures, the aggregates can be treated as infinite chains and the dynamics is dominated by diffusion-driven exciton–exciton annihilation. With increasing temperature the aggregates dissociate into small fragments consisting of very few monomers. This scenario is also supported by the time-dependent anisotropy deduced from polarization-dependent experiments.}, author = {Wolter, Steffen and Aizezers, Janis and Fennel, Franziska and Seidel, Marcus and Würthner, Frank and Kühn, Oliver and Lochbrunner, Stefan}, journal = {New Journal of Physics}, keywords = {myown}, number = 10, pages = 105027, title = {Size-dependent exciton dynamics in one-dimensional perylene bisimide aggregates}, volume = 14, year = 2012 }

  %0 Journal Article %1 1367-2630-14-10-105027 %A Wolter, Steffen %A Aizezers, Janis %A Fennel, Franziska %A Seidel, Marcus %A Würthner, Frank %A Kühn, Oliver %A Lochbrunner, Stefan %D 2012 %J New Journal of Physics %N 10 %P 105027 %T Size-dependent exciton dynamics in one-dimensional perylene bisimide aggregates %U http://stacks.iop.org/1367-2630/14/i=10/a=105027 %V 14 %X The size-dependent exciton dynamics of one-dimensional aggregates of substituted perylene bisimides are studied by ultrafast transient absorption spectroscopy and kinetic Monte-Carlo simulations as a function of the excitation density and the temperature in the range of 25–90 °C. For low temperatures, the aggregates can be treated as infinite chains and the dynamics is dominated by diffusion-driven exciton–exciton annihilation. With increasing temperature the aggregates dissociate into small fragments consisting of very few monomers. This scenario is also supported by the time-dependent anisotropy deduced from polarization-dependent experiments.

• Impact of Molecular Flexibility on Binding Strength and Self-Sorting of Chiral π-Surfaces. Safont-Sempere, Marina M.; Osswald, Peter; Stolte, Matthias; Grüne, Matthias; Renz, Manuel; Kaupp, Martin; Radacki, Krzysztof; Braunschweig, Holger; Würthner, Frank. In J. Am. Chem. Soc., 133(24), pp. 9580–9591. 2011.

  PMID: 21553857
  • [ Abstract ]
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  In this work, we have explored for the first time the influence of conformational flexibility of π-core on chiral self-sorting properties of perylene bisimides (PBIs) that are currently one of the most prominent classes of functional dyes. For this purpose, two series of chiral macrocyclic PBIs 3a–c and 4a–c comprising oligoethylene glycol bridges of different lengths at the 1,7 bay positions were synthesized and their atropo-enantiomers (P and M enantiomers) were resolved. Single crystal analysis of atropo-enantiomerically pure (P)-3a not only confirmed the structural integrity of the ethylene glycol bridged macrocycle but also illustrated the formation of π-stacked dimers with left-handed supramolecular helicity. Our detailed studies with the series of highly soluble chiral PBIs 4a–c by 1- and 2-D 1H NMR techniques, and temperature- and concentration-dependent UV/vis absorption and circular dichroism (CD) spectroscopy revealed that in π–π-stacking dimerization of these PBIs chiral self-recognition (i.e., PP and MM homodimer formation) prevails over self-discrimination (i.e., PM heterodimer formation). Our studies clearly showed that with increasing conformational flexibility of PBI cores imparted by longer bridging units, the binding strength for the dimerization process increases, however, the efficiency for chiral self-recognition decreases. These results are rationalized in terms of an induced-fit mechanism facilitating more planarized π-scaffolds of PBIs containing longer bridging units upon π–π-stacking.

  @article{doi:10.1021/ja202696d, abstract = {In this work, we have explored for the first time the influence of conformational flexibility of π-core on chiral self-sorting properties of perylene bisimides (PBIs) that are currently one of the most prominent classes of functional dyes. For this purpose, two series of chiral macrocyclic PBIs 3a–c and 4a–c comprising oligoethylene glycol bridges of different lengths at the 1,7 bay positions were synthesized and their atropo-enantiomers (P and M enantiomers) were resolved. Single crystal analysis of atropo-enantiomerically pure (P)-3a not only confirmed the structural integrity of the ethylene glycol bridged macrocycle but also illustrated the formation of π-stacked dimers with left-handed supramolecular helicity. Our detailed studies with the series of highly soluble chiral PBIs 4a–c by 1- and 2-D 1H NMR techniques, and temperature- and concentration-dependent UV/vis absorption and circular dichroism (CD) spectroscopy revealed that in π–π-stacking dimerization of these PBIs chiral self-recognition (i.e., PP and MM homodimer formation) prevails over self-discrimination (i.e., PM heterodimer formation). Our studies clearly showed that with increasing conformational flexibility of PBI cores imparted by longer bridging units, the binding strength for the dimerization process increases, however, the efficiency for chiral self-recognition decreases. These results are rationalized in terms of an induced-fit mechanism facilitating more planarized π-scaffolds of PBIs containing longer bridging units upon π–π-stacking.}, author = {Safont-Sempere, Marina M. and Osswald, Peter and Stolte, Matthias and Grüne, Matthias and Renz, Manuel and Kaupp, Martin and Radacki, Krzysztof and Braunschweig, Holger and Würthner, Frank}, journal = {J. Am. Chem. Soc.}, keywords = {myown}, note = {PMID: 21553857}, number = 24, pages = {9580-9591}, title = {Impact of Molecular Flexibility on Binding Strength and Self-Sorting of Chiral π-Surfaces}, volume = 133, year = 2011 }

  %0 Journal Article %1 doi:10.1021/ja202696d %A Safont-Sempere, Marina M. %A Osswald, Peter %A Stolte, Matthias %A Grüne, Matthias %A Renz, Manuel %A Kaupp, Martin %A Radacki, Krzysztof %A Braunschweig, Holger %A Würthner, Frank %D 2011 %J J. Am. Chem. Soc. %N 24 %P 9580-9591 %R 10.1021/ja202696d %T Impact of Molecular Flexibility on Binding Strength and Self-Sorting of Chiral π-Surfaces %U http://dx.doi.org/10.1021/ja202696d %V 133 %X In this work, we have explored for the first time the influence of conformational flexibility of π-core on chiral self-sorting properties of perylene bisimides (PBIs) that are currently one of the most prominent classes of functional dyes. For this purpose, two series of chiral macrocyclic PBIs 3a–c and 4a–c comprising oligoethylene glycol bridges of different lengths at the 1,7 bay positions were synthesized and their atropo-enantiomers (P and M enantiomers) were resolved. Single crystal analysis of atropo-enantiomerically pure (P)-3a not only confirmed the structural integrity of the ethylene glycol bridged macrocycle but also illustrated the formation of π-stacked dimers with left-handed supramolecular helicity. Our detailed studies with the series of highly soluble chiral PBIs 4a–c by 1- and 2-D 1H NMR techniques, and temperature- and concentration-dependent UV/vis absorption and circular dichroism (CD) spectroscopy revealed that in π–π-stacking dimerization of these PBIs chiral self-recognition (i.e., PP and MM homodimer formation) prevails over self-discrimination (i.e., PM heterodimer formation). Our studies clearly showed that with increasing conformational flexibility of PBI cores imparted by longer bridging units, the binding strength for the dimerization process increases, however, the efficiency for chiral self-recognition decreases. These results are rationalized in terms of an induced-fit mechanism facilitating more planarized π-scaffolds of PBIs containing longer bridging units upon π–π-stacking.
• Self-Sorting Phenomena in Complex Supramolecular Systems. Safont-Sempere, Marina M.; Fernández, Gustavo; Würthner, Frank. In Chemical Reviews, 111(9), pp. 5784–5814. 2011.

  PMID: 21846150
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  @article{doi:10.1021/cr100357h, author = {Safont-Sempere, Marina M. and Fernández, Gustavo and Würthner, Frank}, journal = {Chemical Reviews}, keywords = {myown}, note = {PMID: 21846150}, number = 9, pages = {5784-5814}, title = {Self-Sorting Phenomena in Complex Supramolecular Systems}, volume = 111, year = 2011 }

  %0 Journal Article %1 doi:10.1021/cr100357h %A Safont-Sempere, Marina M. %A Fernández, Gustavo %A Würthner, Frank %D 2011 %J Chemical Reviews %N 9 %P 5784-5814 %R 10.1021/cr100357h %T Self-Sorting Phenomena in Complex Supramolecular Systems %U http://dx.doi.org/10.1021/cr100357h %V 111
• Influence of core-substitution on the ultrafast charge separation and recombination in arylamino core-substituted naphthalene diimides. Pugliesi, Igor; Megerle, Uwe; Suraru, Sabin-Lucian; Würthner, Frank; Riedle, Eberhard; Lochbrunner, Stefan. In Chemical Physics Letters, 504(1), pp. 24–28. 2011.
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  Abstract We study the charge separation and recombination of two arylamino core-substituted naphthalene diimides by transient absorption. Both compounds show a 3ps relaxation from the initially excited partial to the full charge transfer state. Quantum chemical calculations show that this process is associated with a twisting of the arylamino substituent. In the twisted conformation the energy gap between ground and excited state is 0.7eV for two amino core-substituents and 0.5eV for one amino and one chloro core-substituent. The larger energy gap leads to a six-fold increase in the lifetime of the fully charge separated state from 11 to 70ps.

  @article{PUGLIESI201124, abstract = {Abstract We study the charge separation and recombination of two arylamino core-substituted naphthalene diimides by transient absorption. Both compounds show a 3ps relaxation from the initially excited partial to the full charge transfer state. Quantum chemical calculations show that this process is associated with a twisting of the arylamino substituent. In the twisted conformation the energy gap between ground and excited state is 0.7eV for two amino core-substituents and 0.5eV for one amino and one chloro core-substituent. The larger energy gap leads to a six-fold increase in the lifetime of the fully charge separated state from 11 to 70ps.}, author = {Pugliesi, Igor and Megerle, Uwe and Suraru, Sabin-Lucian and Würthner, Frank and Riedle, Eberhard and Lochbrunner, Stefan}, journal = {Chemical Physics Letters}, keywords = {myown}, number = 1, pages = {24 - 28}, title = {Influence of core-substitution on the ultrafast charge separation and recombination in arylamino core-substituted naphthalene diimides}, volume = 504, year = 2011 }

  %0 Journal Article %1 PUGLIESI201124 %A Pugliesi, Igor %A Megerle, Uwe %A Suraru, Sabin-Lucian %A Würthner, Frank %A Riedle, Eberhard %A Lochbrunner, Stefan %D 2011 %J Chemical Physics Letters %N 1 %P 24 - 28 %R https://doi.org/10.1016/j.cplett.2011.01.038 %T Influence of core-substitution on the ultrafast charge separation and recombination in arylamino core-substituted naphthalene diimides %U http://www.sciencedirect.com/science/article/pii/S0009261411000637 %V 504 %X Abstract We study the charge separation and recombination of two arylamino core-substituted naphthalene diimides by transient absorption. Both compounds show a 3ps relaxation from the initially excited partial to the full charge transfer state. Quantum chemical calculations show that this process is associated with a twisting of the arylamino substituent. In the twisted conformation the energy gap between ground and excited state is 0.7eV for two amino core-substituents and 0.5eV for one amino and one chloro core-substituent. The larger energy gap leads to a six-fold increase in the lifetime of the fully charge separated state from 11 to 70ps.
• Ring-Closure and Isomerization Capabilities of Spiropyran-Derived Merocyanine Isomers. Buback, Johannes; Nuernberger, Patrick; Kullmann, Martin; Langhojer, Florian; Schmidt, Ralf; Würthner, Frank; Brixner, Tobias. In J. Phys. Chem. A, 115(16), pp. 3924–3935. 2011.

  PMID: 21247207
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  We report the photochemistry of two ring-open isomers, namely TTC and TTT, of a bidirectional photoswitchable spiropyran, 6,8-dinitro-1′,3′,3′-trimethylspiro[2H-1-benzopyran-2,2′-indoline] (6,8-dinitro BIPS). Both isomers are capable of ring closure after excitation with visible fs laser pulses, as disclosed by pump-wavelength-dependent transient absorption experiments in the visible spectral range. The main isomer TTC has its maximum absorption at 560 nm, whereas the minor isomer TTT is red-shifted (600 nm). The excited-state lifetimes differ strongly (τ ≈ 900 ps for TTT and τ ≈ 95 ps for TTC), nevertheless the quantum efficiencies for ring closure (40\% for TTC and 35\% for TTT) and isomerization (1−2\% for TTC and 1−2\% for TTT) are comparable. With regard to the bidirectional photoswitching capabilities, 6,8-dinitro BIPS is the first molecular switch based on a 6π-electrocyclic reaction where both ring-open isomers are capable of ring closure.

  @article{doi:10.1021/jp108322u, abstract = {We report the photochemistry of two ring-open isomers, namely TTC and TTT, of a bidirectional photoswitchable spiropyran, 6,8-dinitro-1′,3′,3′-trimethylspiro[2H-1-benzopyran-2,2′-indoline] (6,8-dinitro BIPS). Both isomers are capable of ring closure after excitation with visible fs laser pulses, as disclosed by pump-wavelength-dependent transient absorption experiments in the visible spectral range. The main isomer TTC has its maximum absorption at 560 nm, whereas the minor isomer TTT is red-shifted (600 nm). The excited-state lifetimes differ strongly (τ ≈ 900 ps for TTT and τ ≈ 95 ps for TTC), nevertheless the quantum efficiencies for ring closure (40\% for TTC and 35\% for TTT) and isomerization (1−2\% for TTC and 1−2\% for TTT) are comparable. With regard to the bidirectional photoswitching capabilities, 6,8-dinitro BIPS is the first molecular switch based on a 6π-electrocyclic reaction where both ring-open isomers are capable of ring closure.}, author = {Buback, Johannes and Nuernberger, Patrick and Kullmann, Martin and Langhojer, Florian and Schmidt, Ralf and Würthner, Frank and Brixner, Tobias}, journal = {J. Phys. Chem. A}, keywords = {myown}, note = {PMID: 21247207}, number = 16, pages = {3924-3935}, title = {Ring-Closure and Isomerization Capabilities of Spiropyran-Derived Merocyanine Isomers}, volume = 115, year = 2011 }

  %0 Journal Article %1 doi:10.1021/jp108322u %A Buback, Johannes %A Nuernberger, Patrick %A Kullmann, Martin %A Langhojer, Florian %A Schmidt, Ralf %A Würthner, Frank %A Brixner, Tobias %D 2011 %J J. Phys. Chem. A %N 16 %P 3924-3935 %R 10.1021/jp108322u %T Ring-Closure and Isomerization Capabilities of Spiropyran-Derived Merocyanine Isomers %U http://dx.doi.org/10.1021/jp108322u %V 115 %X We report the photochemistry of two ring-open isomers, namely TTC and TTT, of a bidirectional photoswitchable spiropyran, 6,8-dinitro-1′,3′,3′-trimethylspiro[2H-1-benzopyran-2,2′-indoline] (6,8-dinitro BIPS). Both isomers are capable of ring closure after excitation with visible fs laser pulses, as disclosed by pump-wavelength-dependent transient absorption experiments in the visible spectral range. The main isomer TTC has its maximum absorption at 560 nm, whereas the minor isomer TTT is red-shifted (600 nm). The excited-state lifetimes differ strongly (τ ≈ 900 ps for TTT and τ ≈ 95 ps for TTC), nevertheless the quantum efficiencies for ring closure (40\% for TTC and 35\% for TTT) and isomerization (1−2\% for TTC and 1−2\% for TTT) are comparable. With regard to the bidirectional photoswitching capabilities, 6,8-dinitro BIPS is the first molecular switch based on a 6π-electrocyclic reaction where both ring-open isomers are capable of ring closure.
• Efficient Solution-Processed Bulk Heterojunction Solar Cells by Antiparallel Supramolecular Arrangement of Dipolar Donor–Acceptor Dyes. Bürckstümmer, Hannah; Tulyakova, Elena V.; Deppisch, Manuela; Lenze, Martin R.; Kronenberg, Nils M.; Gsänger, Marcel; Stolte, Matthias; Meerholz, Klaus; Würthner, Frank. In Angew. Chem. Int. Ed., 50(49), pp. 11628–11632. 2011.
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  A series of dipolar donor–acceptor (D–A) chromophores with aminothiophene donor and different heterocyclic acceptor units is reported. By modulation of the acceptor strength, absorption bands over the whole visible spectrum are accessible as well as adjustment of the frontier molecular orbital levels. The performance of the chromophores in blends with fullerene acceptors in solution-processed bulk heterojunction solar cells was studied and related to the molecular properties of the dyes. In particular, the effect of the large ground-state dipole moments of these dyes was investigated by single crystal X-ray analysis, which revealed antiparallel dimers, resulting in an annihilation of the dipole moments. This specific feature of supramolecular organization explains the excellent performance of merocyanine dyes in organic solar cells. With blends of HB366:PC71BM, the most efficient solar cell with a VOC of 1.0 V, a JSC of 10.2 mA cm−2, and a power-conversion efficiency of 4.5 % was achieved under standard AM1.5, 100 mW cm−2 conditions. Under reduced lighting conditions, even higher efficiencies up to 5.1 % was obtained.

  @article{ANGE:ANGE201105133, abstract = {A series of dipolar donor–acceptor (D–A) chromophores with aminothiophene donor and different heterocyclic acceptor units is reported. By modulation of the acceptor strength, absorption bands over the whole visible spectrum are accessible as well as adjustment of the frontier molecular orbital levels. The performance of the chromophores in blends with fullerene acceptors in solution-processed bulk heterojunction solar cells was studied and related to the molecular properties of the dyes. In particular, the effect of the large ground-state dipole moments of these dyes was investigated by single crystal X-ray analysis, which revealed antiparallel dimers, resulting in an annihilation of the dipole moments. This specific feature of supramolecular organization explains the excellent performance of merocyanine dyes in organic solar cells. With blends of HB366:PC71BM, the most efficient solar cell with a VOC of 1.0 V, a JSC of 10.2 mA cm−2, and a power-conversion efficiency of 4.5 % was achieved under standard AM1.5, 100 mW cm−2 conditions. Under reduced lighting conditions, even higher efficiencies up to 5.1 % was obtained.}, author = {Bürckstümmer, Hannah and Tulyakova, Elena V. and Deppisch, Manuela and Lenze, Martin R. and Kronenberg, Nils M. and Gsänger, Marcel and Stolte, Matthias and Meerholz, Klaus and Würthner, Frank}, journal = {Angew. Chem. Int. Ed.}, keywords = {myown}, number = 49, pages = {11628 - 11632}, publisher = {WILEY-VCH Verlag}, title = {Efficient Solution-Processed Bulk Heterojunction Solar Cells by Antiparallel Supramolecular Arrangement of Dipolar Donor–Acceptor Dyes}, volume = 50, year = 2011 }

  %0 Journal Article %1 ANGE:ANGE201105133 %A Bürckstümmer, Hannah %A Tulyakova, Elena V. %A Deppisch, Manuela %A Lenze, Martin R. %A Kronenberg, Nils M. %A Gsänger, Marcel %A Stolte, Matthias %A Meerholz, Klaus %A Würthner, Frank %D 2011 %I WILEY-VCH Verlag %J Angew. Chem. Int. Ed. %N 49 %P 11628 - 11632 %R 10.1002/anie.201105133 %T Efficient Solution-Processed Bulk Heterojunction Solar Cells by Antiparallel Supramolecular Arrangement of Dipolar Donor–Acceptor Dyes %U https://onlinelibrary.wiley.com/doi/full/10.1002/anie.201105133 %V 50 %X A series of dipolar donor–acceptor (D–A) chromophores with aminothiophene donor and different heterocyclic acceptor units is reported. By modulation of the acceptor strength, absorption bands over the whole visible spectrum are accessible as well as adjustment of the frontier molecular orbital levels. The performance of the chromophores in blends with fullerene acceptors in solution-processed bulk heterojunction solar cells was studied and related to the molecular properties of the dyes. In particular, the effect of the large ground-state dipole moments of these dyes was investigated by single crystal X-ray analysis, which revealed antiparallel dimers, resulting in an annihilation of the dipole moments. This specific feature of supramolecular organization explains the excellent performance of merocyanine dyes in organic solar cells. With blends of HB366:PC71BM, the most efficient solar cell with a VOC of 1.0 V, a JSC of 10.2 mA cm−2, and a power-conversion efficiency of 4.5 % was achieved under standard AM1.5, 100 mW cm−2 conditions. Under reduced lighting conditions, even higher efficiencies up to 5.1 % was obtained.
• Halochromic Phenolate Perylene Bisimides with Unprecedented NIR Spectroscopic Properties. Lin, Mei-Jin; Fimmel, Benjamin; Radacki, Krzysztof; Würthner, Frank. In Angew. Chem. Int. Ed., 50(46), pp. 10847–10850. 2011.
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  @article{ANIE:ANIE201105129, author = {Lin, Mei-Jin and Fimmel, Benjamin and Radacki, Krzysztof and Würthner, Frank}, journal = {Angew. Chem. Int. Ed.}, keywords = {myown}, number = 46, pages = {10847–10850}, publisher = {WILEY-VCH Verlag}, title = {Halochromic Phenolate Perylene Bisimides with Unprecedented NIR Spectroscopic Properties}, volume = 50, year = 2011 }

  %0 Journal Article %1 ANIE:ANIE201105129 %A Lin, Mei-Jin %A Fimmel, Benjamin %A Radacki, Krzysztof %A Würthner, Frank %D 2011 %I WILEY-VCH Verlag %J Angew. Chem. Int. Ed. %N 46 %P 10847--10850 %R 10.1002/anie.201105129 %T Halochromic Phenolate Perylene Bisimides with Unprecedented NIR Spectroscopic Properties %U http://dx.doi.org/10.1002/anie.201105129 %V 50
• Diketopyrrolopyrrole as a p-channel organic semiconductor for high performance OTFTs. Suraru, Sabin-Lucian; Zschieschang, Ute; Klauk, Hagen; Würthner, Frank. In Chem. Commun., 47(6), pp. 1767–1769. 2011.
  • [ Abstract ]
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  A new diketopyrrolopyrrole derivative 1 exhibits excellent hole mobilities of 0.7 cm2 V-1 s-1 and a current on/off ratio of 106 under ambient conditions in bottom-gate, top-contact organic thin film transistors (OTFTs) fabricated by vacuum deposition.

  @article{C0CC04395H, abstract = {A new diketopyrrolopyrrole derivative 1 exhibits excellent hole mobilities of 0.7 cm2 V-1 s-1 and a current on/off ratio of 106 under ambient conditions in bottom-gate{,} top-contact organic thin film transistors (OTFTs) fabricated by vacuum deposition.}, author = {Suraru, Sabin-Lucian and Zschieschang, Ute and Klauk, Hagen and Würthner, Frank}, journal = {Chem. Commun.}, keywords = {myown}, number = 6, pages = {1767-1769}, publisher = {The Royal Society of Chemistry}, title = {Diketopyrrolopyrrole as a p-channel organic semiconductor for high performance OTFTs}, volume = 47, year = 2011 }

  %0 Journal Article %1 C0CC04395H %A Suraru, Sabin-Lucian %A Zschieschang, Ute %A Klauk, Hagen %A Würthner, Frank %D 2011 %I The Royal Society of Chemistry %J Chem. Commun. %N 6 %P 1767-1769 %R 10.1039/C0CC04395H %T Diketopyrrolopyrrole as a p-channel organic semiconductor for high performance OTFTs %U http://dx.doi.org/10.1039/C0CC04395H %V 47 %X A new diketopyrrolopyrrole derivative 1 exhibits excellent hole mobilities of 0.7 cm2 V-1 s-1 and a current on/off ratio of 106 under ambient conditions in bottom-gate, top-contact organic thin film transistors (OTFTs) fabricated by vacuum deposition.
• Chiral Amplification, Kinetic Pathways, and Morphogenesis of Helical Nanorods upon Self-assembly of Dipolar Merocyanine Dyes. Lohr, Andreas; Würthner, Frank. In Israel Journal of Chemistry, 51(10), pp. 1052–1066. 2011.
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  In this account we report on the self-assembly of bis(merocyanine) dyes into helical nanorods by emphasizing the kinetic pathways and the mechanistic aspects leading to chiral amplification. A complex self-assembly sequence of these dipolar dyes into well-defined helical nanorod structures has been revealed spectroscopically by time-dependent circular dichroism (CD) spectroscopy and microscopically by atomic force microscopy (AFM). This self-assembly sequence proceeds over several kinetically formed supramolecular intermediates, which are distinguished by their morphology and (chir)optical properties. Moreover, the kinetics for the formation of homochiral nanorods was studied, revealing that chiral amplification mechanisms can operate at different stages of self-assembly to afford energetically favored structures. The rates of these processes decrease strongly with decreasing chiral bias in the monomers or decreasing fraction of chiral co-monomers in mixtures of chiral and achiral monomers. For the fully equilibrated nanorods, however, strong chiral amplification directed by the “majority-rules” or “sergeants-and-soldiers” effect is observed.

  @article{IJCH:IJCH201100023, abstract = {In this account we report on the self-assembly of bis(merocyanine) dyes into helical nanorods by emphasizing the kinetic pathways and the mechanistic aspects leading to chiral amplification. A complex self-assembly sequence of these dipolar dyes into well-defined helical nanorod structures has been revealed spectroscopically by time-dependent circular dichroism (CD) spectroscopy and microscopically by atomic force microscopy (AFM). This self-assembly sequence proceeds over several kinetically formed supramolecular intermediates, which are distinguished by their morphology and (chir)optical properties. Moreover, the kinetics for the formation of homochiral nanorods was studied, revealing that chiral amplification mechanisms can operate at different stages of self-assembly to afford energetically favored structures. The rates of these processes decrease strongly with decreasing chiral bias in the monomers or decreasing fraction of chiral co-monomers in mixtures of chiral and achiral monomers. For the fully equilibrated nanorods, however, strong chiral amplification directed by the “majority-rules” or “sergeants-and-soldiers” effect is observed.}, author = {Lohr, Andreas and Würthner, Frank}, journal = {Israel Journal of Chemistry}, keywords = {myown}, number = 10, pages = {1052–1066}, publisher = {WILEY-VCH Verlag}, title = {Chiral Amplification, Kinetic Pathways, and Morphogenesis of Helical Nanorods upon Self-assembly of Dipolar Merocyanine Dyes}, volume = 51, year = 2011 }

  %0 Journal Article %1 IJCH:IJCH201100023 %A Lohr, Andreas %A Würthner, Frank %D 2011 %I WILEY-VCH Verlag %J Israel Journal of Chemistry %N 10 %P 1052--1066 %R 10.1002/ijch.201100023 %T Chiral Amplification, Kinetic Pathways, and Morphogenesis of Helical Nanorods upon Self-assembly of Dipolar Merocyanine Dyes %U http://dx.doi.org/10.1002/ijch.201100023 %V 51 %X In this account we report on the self-assembly of bis(merocyanine) dyes into helical nanorods by emphasizing the kinetic pathways and the mechanistic aspects leading to chiral amplification. A complex self-assembly sequence of these dipolar dyes into well-defined helical nanorod structures has been revealed spectroscopically by time-dependent circular dichroism (CD) spectroscopy and microscopically by atomic force microscopy (AFM). This self-assembly sequence proceeds over several kinetically formed supramolecular intermediates, which are distinguished by their morphology and (chir)optical properties. Moreover, the kinetics for the formation of homochiral nanorods was studied, revealing that chiral amplification mechanisms can operate at different stages of self-assembly to afford energetically favored structures. The rates of these processes decrease strongly with decreasing chiral bias in the monomers or decreasing fraction of chiral co-monomers in mixtures of chiral and achiral monomers. For the fully equilibrated nanorods, however, strong chiral amplification directed by the “majority-rules” or “sergeants-and-soldiers” effect is observed.
• One-Dimensional Exciton Diffusion in Perylene Bisimide Aggregates. Marciniak, Henning; Li, Xue-Qing; Würthner, Frank; Lochbrunner, Stefan. In J. Phys. Chem. A, 115(5), pp. 648–654. 2011.

  PMID: 21192672
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  The dynamics and mobility of excitons in J-aggregates of perylene bisimides are investigated by transient absorption spectroscopy with a time resolution of 50 fs. The transient spectra are compatible with an exciton delocalization length of two monomers and indicate that vibrational and configurational relaxation processes are not relevant for the spectroscopic properties of the aggregates. Increasing the pump pulse energy and in that way the initial exciton density results in an accelerated signal decay and pronounced exciton−exciton annihilation dynamics. Modeling the data by assuming a diffusive exciton motion reveals that the excitons cannot migrate freely in all three directions of space but their mobility is restricted to one dimension. The observed anisotropy supports this picture and points against direct Förster-transfer-mediated annihilation between the excitons. A diffusion constant of 1.29 nm2/ps is deduced from the fitting procedure that corresponds to a maximal exciton diffusion length of 96 nm for the measured exciton lifetime of 3.6 ns. The findings indicate that J-aggregates of perylene bisimides are promising building blocks to facilitate directed energy transport in optoelectronic organic devices or artificial light-harvesting systems.

  @article{doi:10.1021/jp107407p, abstract = {The dynamics and mobility of excitons in J-aggregates of perylene bisimides are investigated by transient absorption spectroscopy with a time resolution of 50 fs. The transient spectra are compatible with an exciton delocalization length of two monomers and indicate that vibrational and configurational relaxation processes are not relevant for the spectroscopic properties of the aggregates. Increasing the pump pulse energy and in that way the initial exciton density results in an accelerated signal decay and pronounced exciton−exciton annihilation dynamics. Modeling the data by assuming a diffusive exciton motion reveals that the excitons cannot migrate freely in all three directions of space but their mobility is restricted to one dimension. The observed anisotropy supports this picture and points against direct Förster-transfer-mediated annihilation between the excitons. A diffusion constant of 1.29 nm2/ps is deduced from the fitting procedure that corresponds to a maximal exciton diffusion length of 96 nm for the measured exciton lifetime of 3.6 ns. The findings indicate that J-aggregates of perylene bisimides are promising building blocks to facilitate directed energy transport in optoelectronic organic devices or artificial light-harvesting systems.}, author = {Marciniak, Henning and Li, Xue-Qing and Würthner, Frank and Lochbrunner, Stefan}, journal = {J. Phys. Chem. A}, keywords = {myown}, note = {PMID: 21192672}, number = 5, pages = {648-654}, title = {One-Dimensional Exciton Diffusion in Perylene Bisimide Aggregates}, volume = 115, year = 2011 }

  %0 Journal Article %1 doi:10.1021/jp107407p %A Marciniak, Henning %A Li, Xue-Qing %A Würthner, Frank %A Lochbrunner, Stefan %D 2011 %J J. Phys. Chem. A %N 5 %P 648-654 %R 10.1021/jp107407p %T One-Dimensional Exciton Diffusion in Perylene Bisimide Aggregates %U http://dx.doi.org/10.1021/jp107407p %V 115 %X The dynamics and mobility of excitons in J-aggregates of perylene bisimides are investigated by transient absorption spectroscopy with a time resolution of 50 fs. The transient spectra are compatible with an exciton delocalization length of two monomers and indicate that vibrational and configurational relaxation processes are not relevant for the spectroscopic properties of the aggregates. Increasing the pump pulse energy and in that way the initial exciton density results in an accelerated signal decay and pronounced exciton−exciton annihilation dynamics. Modeling the data by assuming a diffusive exciton motion reveals that the excitons cannot migrate freely in all three directions of space but their mobility is restricted to one dimension. The observed anisotropy supports this picture and points against direct Förster-transfer-mediated annihilation between the excitons. A diffusion constant of 1.29 nm2/ps is deduced from the fitting procedure that corresponds to a maximal exciton diffusion length of 96 nm for the measured exciton lifetime of 3.6 ns. The findings indicate that J-aggregates of perylene bisimides are promising building blocks to facilitate directed energy transport in optoelectronic organic devices or artificial light-harvesting systems.
• Toward Functional Inorganic/Organic Hybrids: Phenoxy-allyl-PTCDI Synthesis, Experimentally and Theoretically Determined Properties of the Isolated Molecule, Layer Characteristics, and the Interface Formation of Phenoxy-allyl-PTCDI on Si(111):H Determined by SXPS and DFT. Decker, Andreas; Suraru, Sabin-Lucian; Rubio-Pons, Oscar; Mankel, Eric; Bockstedte, Michel; Thoss, Michael; Würthner, Frank; Mayer, Thomas; Jaegermann, Wolfram. In J. Phys. Chem. C., 115(43), pp. 21139–21150. 2011.
  • [ Abstract ]
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  A new perylene diimide derivative, namely N,N′-diallyl-1,6,7,12-tetraphenoxyperylene-3,4:9,10-tetracarboxylic acid diimide (phenoxy-allyl-PTCDI, abbreviated PA-PTCDI), is introduced. The investigations presented in this paper aim at finding a molecule for use as a sensitzer in thin film silicon solar cells in order to enhance efficiency. The synthesis is described along with optical and electrochemical measurements of PA-PTCDI in solution. A good agreement is found between the measured data and theoretical calculations. The molecule is characterized further by optical and photoemission data on thin films, which also show that the dye can be sublimed in vacuum. The interface between the dye and silicon is investigated on the model system Si(111):H with synchrotron-induced photoemission spectroscopy. The result is an electronic lineup with the gap centers of silicon and PA-PTCDI almost at identical positions and thus very similar band discontinuities from the lowest unoccupied molecular orbital (LUMO) to the conduction band as well as from the highest occupied molecular orbital (HOMO) to the valence band. This clearly permits a transfer of photogenerated electrons and holes from PA-PTCDI to silicon. The experimental valence band discontinuity matches very well the value calculated for a very similar PTCDI molecule.

  @article{doi:10.1021/jp205294h, abstract = {A new perylene diimide derivative, namely N,N′-diallyl-1,6,7,12-tetraphenoxyperylene-3,4:9,10-tetracarboxylic acid diimide (phenoxy-allyl-PTCDI, abbreviated PA-PTCDI), is introduced. The investigations presented in this paper aim at finding a molecule for use as a sensitzer in thin film silicon solar cells in order to enhance efficiency. The synthesis is described along with optical and electrochemical measurements of PA-PTCDI in solution. A good agreement is found between the measured data and theoretical calculations. The molecule is characterized further by optical and photoemission data on thin films, which also show that the dye can be sublimed in vacuum. The interface between the dye and silicon is investigated on the model system Si(111):H with synchrotron-induced photoemission spectroscopy. The result is an electronic lineup with the gap centers of silicon and PA-PTCDI almost at identical positions and thus very similar band discontinuities from the lowest unoccupied molecular orbital (LUMO) to the conduction band as well as from the highest occupied molecular orbital (HOMO) to the valence band. This clearly permits a transfer of photogenerated electrons and holes from PA-PTCDI to silicon. The experimental valence band discontinuity matches very well the value calculated for a very similar PTCDI molecule.}, author = {Decker, Andreas and Suraru, Sabin-Lucian and Rubio-Pons, Oscar and Mankel, Eric and Bockstedte, Michel and Thoss, Michael and Würthner, Frank and Mayer, Thomas and Jaegermann, Wolfram}, journal = {J. Phys. Chem. C.}, keywords = {myown}, number = 43, pages = {21139-21150}, title = {Toward Functional Inorganic/Organic Hybrids: Phenoxy-allyl-PTCDI Synthesis, Experimentally and Theoretically Determined Properties of the Isolated Molecule, Layer Characteristics, and the Interface Formation of Phenoxy-allyl-PTCDI on Si(111):H Determined by SXPS and DFT}, volume = 115, year = 2011 }

  %0 Journal Article %1 doi:10.1021/jp205294h %A Decker, Andreas %A Suraru, Sabin-Lucian %A Rubio-Pons, Oscar %A Mankel, Eric %A Bockstedte, Michel %A Thoss, Michael %A Würthner, Frank %A Mayer, Thomas %A Jaegermann, Wolfram %D 2011 %J J. Phys. Chem. C. %N 43 %P 21139-21150 %R 10.1021/jp205294h %T Toward Functional Inorganic/Organic Hybrids: Phenoxy-allyl-PTCDI Synthesis, Experimentally and Theoretically Determined Properties of the Isolated Molecule, Layer Characteristics, and the Interface Formation of Phenoxy-allyl-PTCDI on Si(111):H Determined by SXPS and DFT %U http://dx.doi.org/10.1021/jp205294h %V 115 %X A new perylene diimide derivative, namely N,N′-diallyl-1,6,7,12-tetraphenoxyperylene-3,4:9,10-tetracarboxylic acid diimide (phenoxy-allyl-PTCDI, abbreviated PA-PTCDI), is introduced. The investigations presented in this paper aim at finding a molecule for use as a sensitzer in thin film silicon solar cells in order to enhance efficiency. The synthesis is described along with optical and electrochemical measurements of PA-PTCDI in solution. A good agreement is found between the measured data and theoretical calculations. The molecule is characterized further by optical and photoemission data on thin films, which also show that the dye can be sublimed in vacuum. The interface between the dye and silicon is investigated on the model system Si(111):H with synchrotron-induced photoemission spectroscopy. The result is an electronic lineup with the gap centers of silicon and PA-PTCDI almost at identical positions and thus very similar band discontinuities from the lowest unoccupied molecular orbital (LUMO) to the conduction band as well as from the highest occupied molecular orbital (HOMO) to the valence band. This clearly permits a transfer of photogenerated electrons and holes from PA-PTCDI to silicon. The experimental valence band discontinuity matches very well the value calculated for a very similar PTCDI molecule.
• Tunneling anisotropic magnetoresistance in organic spin valves. Grünewald, M.; Wahler, M.; Schumann, F.; Michelfeit, M.; Gould, C.; Schmidt, R.; Würthner, F.; Schmidt, G.; Molenkamp, L. W. In Phys. Rev. B, 84(12), p. 125208. 2011.
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  @article{PhysRevB.84.125208, author = {Grünewald, M. and Wahler, M. and Schumann, F. and Michelfeit, M. and Gould, C. and Schmidt, R. and Würthner, F. and Schmidt, G. and Molenkamp, L. W.}, journal = {Phys. Rev. B}, keywords = {myown}, month = {09}, number = 12, pages = 125208, publisher = {American Physical Society}, title = {Tunneling anisotropic magnetoresistance in organic spin valves}, volume = 84, year = 2011 }

  %0 Journal Article %1 PhysRevB.84.125208 %A Grünewald, M. %A Wahler, M. %A Schumann, F. %A Michelfeit, M. %A Gould, C. %A Schmidt, R. %A Würthner, F. %A Schmidt, G. %A Molenkamp, L. W. %D 2011 %I American Physical Society %J Phys. Rev. B %N 12 %P 125208 %R 10.1103/PhysRevB.84.125208 %T Tunneling anisotropic magnetoresistance in organic spin valves %U https://link.aps.org/doi/10.1103/PhysRevB.84.125208 %V 84
• Simple, Highly Efficient Vacuum-Processed Bulk Heterojunction Solar Cells Based on Merocyanine Dyes. Steinmann, Vera; Kronenberg, Nils M.; Lenze, Martin R.; Graf, Steven M.; Hertel, Dirk; Meerholz, Klaus; Bürckstümmer, Hannah; Tulyakova, Elena V.; Würthner, Frank. In Advanced Energy Materials, 1(5), pp. 888–893. 2011.
  • [ Abstract ]
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  In order to be competitive on the energy market, organic solar cells with higher efficiency are needed. To date, polymer solar cells have retained the lead with efficiencies of up to 8%. However, research on small molecule solar cells has been catching up throughout recent years and is showing similar efficiencies, however, only for more sophisticated multilayer device configurations. In this work, a simple, highly efficient, vacuum-processed small molecule solar cell based on merocyanine dyes – traditional colorants that can easily be mass-produced and purified – is presented. In the past, merocyanines have been successfully introduced in solution-processed as well as vacuum-processed devices, demonstrating efficiencies up to 4.9%. Here, further optimization of devices is achieved while keeping the same simple layer stack, ultimately leading to efficiencies beyond the 6% mark. In addition, physical properties such as the charge carrier transport and the cell performance under various light intensities are addressed.

  @article{AENM:AENM201100283, abstract = {In order to be competitive on the energy market, organic solar cells with higher efficiency are needed. To date, polymer solar cells have retained the lead with efficiencies of up to 8%. However, research on small molecule solar cells has been catching up throughout recent years and is showing similar efficiencies, however, only for more sophisticated multilayer device configurations. In this work, a simple, highly efficient, vacuum-processed small molecule solar cell based on merocyanine dyes – traditional colorants that can easily be mass-produced and purified – is presented. In the past, merocyanines have been successfully introduced in solution-processed as well as vacuum-processed devices, demonstrating efficiencies up to 4.9%. Here, further optimization of devices is achieved while keeping the same simple layer stack, ultimately leading to efficiencies beyond the 6% mark. In addition, physical properties such as the charge carrier transport and the cell performance under various light intensities are addressed.}, author = {Steinmann, Vera and Kronenberg, Nils M. and Lenze, Martin R. and Graf, Steven M. and Hertel, Dirk and Meerholz, Klaus and Bürckstümmer, Hannah and Tulyakova, Elena V. and Würthner, Frank}, journal = {Advanced Energy Materials}, keywords = {myown}, number = 5, pages = {888–893}, publisher = {WILEY-VCH Verlag}, title = {Simple, Highly Efficient Vacuum-Processed Bulk Heterojunction Solar Cells Based on Merocyanine Dyes}, volume = 1, year = 2011 }

  %0 Journal Article %1 AENM:AENM201100283 %A Steinmann, Vera %A Kronenberg, Nils M. %A Lenze, Martin R. %A Graf, Steven M. %A Hertel, Dirk %A Meerholz, Klaus %A Bürckstümmer, Hannah %A Tulyakova, Elena V. %A Würthner, Frank %D 2011 %I WILEY-VCH Verlag %J Advanced Energy Materials %N 5 %P 888--893 %R 10.1002/aenm.201100283 %T Simple, Highly Efficient Vacuum-Processed Bulk Heterojunction Solar Cells Based on Merocyanine Dyes %U http://dx.doi.org/10.1002/aenm.201100283 %V 1 %X In order to be competitive on the energy market, organic solar cells with higher efficiency are needed. To date, polymer solar cells have retained the lead with efficiencies of up to 8%. However, research on small molecule solar cells has been catching up throughout recent years and is showing similar efficiencies, however, only for more sophisticated multilayer device configurations. In this work, a simple, highly efficient, vacuum-processed small molecule solar cell based on merocyanine dyes – traditional colorants that can easily be mass-produced and purified – is presented. In the past, merocyanines have been successfully introduced in solution-processed as well as vacuum-processed devices, demonstrating efficiencies up to 4.9%. Here, further optimization of devices is achieved while keeping the same simple layer stack, ultimately leading to efficiencies beyond the 6% mark. In addition, physical properties such as the charge carrier transport and the cell performance under various light intensities are addressed.
• A simple merocyanine tandem solar cell with extraordinarily high open-circuit voltage. Steinmann, V.; Kronenberg, N. M.; Lenze, M. R.; Graf, S. M.; Hertel, D.; Bürckstümmer, H.; Würthner, F.; Meerholz, K. In Applied Physics Letters, 99(19), p. 193306. 2011.
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  @article{doi:10.1063/1.3657145, author = {Steinmann, V. and Kronenberg, N. M. and Lenze, M. R. and Graf, S. M. and Hertel, D. and Bürckstümmer, H. and Würthner, F. and Meerholz, K.}, journal = {Applied Physics Letters}, keywords = {myown}, number = 19, pages = 193306, title = {A simple merocyanine tandem solar cell with extraordinarily high open-circuit voltage}, volume = 99, year = 2011 }

  %0 Journal Article %1 doi:10.1063/1.3657145 %A Steinmann, V. %A Kronenberg, N. M. %A Lenze, M. R. %A Graf, S. M. %A Hertel, D. %A Bürckstümmer, H. %A Würthner, F. %A Meerholz, K. %D 2011 %J Applied Physics Letters %N 19 %P 193306 %R 10.1063/1.3657145 %T A simple merocyanine tandem solar cell with extraordinarily high open-circuit voltage %U https://doi.org/10.1063/1.3657145 %V 99
• Thiophene-functionalized isoindigo dyes bearing electron donor substituents with absorptions approaching the near infrared region. Bialas, David; Suraru, Sabin-Lucian; Schmidt, Ralf; Würthner, Frank. In Org. Biomol. Chem., 9(17), pp. 6127–6132. 2011.
  • [ Abstract ]
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  A series of six new, highly soluble N,N[prime or minute]-dialkylated isoindigo derivatives bearing different electron donating thiophene units at the 6,6[prime or minute]-positions were synthesized by Stille cross-coupling reaction. The optical and electrochemical properties of these dyes were studied by UV-vis spectroscopy and cyclic voltammetry, revealing a good tunability of their electronic properties by peripheral substituents with amino groups leading to strong absorption reaching the NIR region. The DFT calculations of the frontier molecular orbitals of these dyes corroborate the observed substituent effect on absorption and redox properties.

  @article{C1OB05508A, abstract = {A series of six new{,} highly soluble N{,}N[prime or minute]-dialkylated isoindigo derivatives bearing different electron donating thiophene units at the 6{,}6[prime or minute]-positions were synthesized by Stille cross-coupling reaction. The optical and electrochemical properties of these dyes were studied by UV-vis spectroscopy and cyclic voltammetry{,} revealing a good tunability of their electronic properties by peripheral substituents with amino groups leading to strong absorption reaching the NIR region. The DFT calculations of the frontier molecular orbitals of these dyes corroborate the observed substituent effect on absorption and redox properties.}, author = {Bialas, David and Suraru, Sabin-Lucian and Schmidt, Ralf and Würthner, Frank}, journal = {Org. Biomol. Chem.}, keywords = {myown}, number = 17, pages = {6127-6132}, publisher = {The Royal Society of Chemistry}, title = {Thiophene-functionalized isoindigo dyes bearing electron donor substituents with absorptions approaching the near infrared region}, volume = 9, year = 2011 }

  %0 Journal Article %1 C1OB05508A %A Bialas, David %A Suraru, Sabin-Lucian %A Schmidt, Ralf %A Würthner, Frank %D 2011 %I The Royal Society of Chemistry %J Org. Biomol. Chem. %N 17 %P 6127-6132 %R 10.1039/C1OB05508A %T Thiophene-functionalized isoindigo dyes bearing electron donor substituents with absorptions approaching the near infrared region %U http://dx.doi.org/10.1039/C1OB05508A %V 9 %X A series of six new, highly soluble N,N[prime or minute]-dialkylated isoindigo derivatives bearing different electron donating thiophene units at the 6,6[prime or minute]-positions were synthesized by Stille cross-coupling reaction. The optical and electrochemical properties of these dyes were studied by UV-vis spectroscopy and cyclic voltammetry, revealing a good tunability of their electronic properties by peripheral substituents with amino groups leading to strong absorption reaching the NIR region. The DFT calculations of the frontier molecular orbitals of these dyes corroborate the observed substituent effect on absorption and redox properties.
• High-Mobility Air-Stable Solution-Shear-Processed n-Channel Organic Transistors Based on Core-Chlorinated Naphthalene Diimides. Lee, Wen-Ya; Oh, Joon Hak; Suraru, Sabin-Lucian; Chen, Wen-Chang; Würthner, Frank; Bao, Zhenan. In Advanced Functional Materials, 21(21), pp. 4173–4181. 2011.
  • [ Abstract ]
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  High charge carrier mobility solution-processed n-channel organic thin-film transistors (OTFTs) based on core-chlorinated naphthalene tetracarboxylic diimides (NDIs) with fluoroalkyl chains are demonstrated. These OTFTs were prepared through a solution shearing method. Core-chlorination of NDIs not only increases the electron mobilities of OTFTs, but also enhances their air stability, since the chlorination in the NDI core lowers the lowest unoccupied molecular orbital (LUMO) levels. The air-stability of dichlorinated NDI was better than that of the tetrachlorinated NDIs, presumably due to the fact that dichlorinated NDIs have a denser packing of the fluoroalkyl chains and less grain boundaries on the surface, reducing the invasion pathway of ambient oxygen and moisture. The devices of dichlorinated NDIs exhibit good OTFT performance, even after storage in air for one and a half months. Charge transport anisotropy is observed from the dichlorinated NDI. A dichlorinated NDI with −CH2C3F7 side chains reveals high mobilities of up to 0.22 and 0.57 cm2 V−1 s−1 in parallel and perpendicular direction, respectively, with regard to the shearing direction. This mobility anisotropy is related to the grain morphology. In addition, we find that the solution-shearing deposition affects the molecular orientation in the crystalline thin films and lowers the d(001)-spacing (the out-of-plane interlayer spacing), compared to the vapor-deposited thin films. Core-chlorinated NDI derivatives are found to be highly suitable for n-channel active materials in low-cost solution-processed organic electronics.

  @article{ADFM:ADFM201101606, abstract = {High charge carrier mobility solution-processed n-channel organic thin-film transistors (OTFTs) based on core-chlorinated naphthalene tetracarboxylic diimides (NDIs) with fluoroalkyl chains are demonstrated. These OTFTs were prepared through a solution shearing method. Core-chlorination of NDIs not only increases the electron mobilities of OTFTs, but also enhances their air stability, since the chlorination in the NDI core lowers the lowest unoccupied molecular orbital (LUMO) levels. The air-stability of dichlorinated NDI was better than that of the tetrachlorinated NDIs, presumably due to the fact that dichlorinated NDIs have a denser packing of the fluoroalkyl chains and less grain boundaries on the surface, reducing the invasion pathway of ambient oxygen and moisture. The devices of dichlorinated NDIs exhibit good OTFT performance, even after storage in air for one and a half months. Charge transport anisotropy is observed from the dichlorinated NDI. A dichlorinated NDI with −CH2C3F7 side chains reveals high mobilities of up to 0.22 and 0.57 cm2 V−1 s−1 in parallel and perpendicular direction, respectively, with regard to the shearing direction. This mobility anisotropy is related to the grain morphology. In addition, we find that the solution-shearing deposition affects the molecular orientation in the crystalline thin films and lowers the d(001)-spacing (the out-of-plane interlayer spacing), compared to the vapor-deposited thin films. Core-chlorinated NDI derivatives are found to be highly suitable for n-channel active materials in low-cost solution-processed organic electronics.}, author = {Lee, Wen-Ya and Oh, Joon Hak and Suraru, Sabin-Lucian and Chen, Wen-Chang and Würthner, Frank and Bao, Zhenan}, journal = {Advanced Functional Materials}, keywords = {myown}, number = 21, pages = {4173–4181}, publisher = {WILEY-VCH Verlag}, title = {High-Mobility Air-Stable Solution-Shear-Processed n-Channel Organic Transistors Based on Core-Chlorinated Naphthalene Diimides}, volume = 21, year = 2011 }

  %0 Journal Article %1 ADFM:ADFM201101606 %A Lee, Wen-Ya %A Oh, Joon Hak %A Suraru, Sabin-Lucian %A Chen, Wen-Chang %A Würthner, Frank %A Bao, Zhenan %D 2011 %I WILEY-VCH Verlag %J Advanced Functional Materials %N 21 %P 4173--4181 %R 10.1002/adfm.201101606 %T High-Mobility Air-Stable Solution-Shear-Processed n-Channel Organic Transistors Based on Core-Chlorinated Naphthalene Diimides %U http://dx.doi.org/10.1002/adfm.201101606 %V 21 %X High charge carrier mobility solution-processed n-channel organic thin-film transistors (OTFTs) based on core-chlorinated naphthalene tetracarboxylic diimides (NDIs) with fluoroalkyl chains are demonstrated. These OTFTs were prepared through a solution shearing method. Core-chlorination of NDIs not only increases the electron mobilities of OTFTs, but also enhances their air stability, since the chlorination in the NDI core lowers the lowest unoccupied molecular orbital (LUMO) levels. The air-stability of dichlorinated NDI was better than that of the tetrachlorinated NDIs, presumably due to the fact that dichlorinated NDIs have a denser packing of the fluoroalkyl chains and less grain boundaries on the surface, reducing the invasion pathway of ambient oxygen and moisture. The devices of dichlorinated NDIs exhibit good OTFT performance, even after storage in air for one and a half months. Charge transport anisotropy is observed from the dichlorinated NDI. A dichlorinated NDI with −CH2C3F7 side chains reveals high mobilities of up to 0.22 and 0.57 cm2 V−1 s−1 in parallel and perpendicular direction, respectively, with regard to the shearing direction. This mobility anisotropy is related to the grain morphology. In addition, we find that the solution-shearing deposition affects the molecular orientation in the crystalline thin films and lowers the d(001)-spacing (the out-of-plane interlayer spacing), compared to the vapor-deposited thin films. Core-chlorinated NDI derivatives are found to be highly suitable for n-channel active materials in low-cost solution-processed organic electronics.
• Assembly of DNA Triangles Mediated by Perylene Bisimide Caps. Menacher, Florian; Stepanenko, Vladimir; Würthner, Frank; Wagenknecht, Hans-Achim. In Chemistry – A European Journal, 17(24), pp. 6683–6688. 2011.
  • [ Abstract ]
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  Perylene bisimides (PBI) have been synthetically incorporated as caps onto a Y-shaped DNA triple strand. These PBI caps serve as “sticky” ends in the spontaneous assembly of larger DNA ensembles, linking the triangular DNA through stacking interactions. This, in turn, yields a hypsochromic shift in the absorption and a red shift in the fluorescence as characteristic optical readouts. This assembly occurs spontaneously without any enzymatic ligation process and without the use of overhanging DNA as sticky ends. Instead, dimerizations of the PBI chromophores in the assembly are controlled by the DNA as a structural scaffold. Thereby, the PBI-driven assembly is fully reversible. Due to the fact that PBI dimerization does not occur in the single strand, the aggregates can be destroyed by thermal dehybridization of the DNA scaffold and reassembled by reannealing of the DNA construct. In view of the fact that PBI forms stable radical anions, the presented DNA architectures are not only interesting optical biomaterials, but are also promising materials for molecular electronics with DNA.

  @article{CHEM:CHEM201100141, abstract = {Perylene bisimides (PBI) have been synthetically incorporated as caps onto a Y-shaped DNA triple strand. These PBI caps serve as “sticky” ends in the spontaneous assembly of larger DNA ensembles, linking the triangular DNA through stacking interactions. This, in turn, yields a hypsochromic shift in the absorption and a red shift in the fluorescence as characteristic optical readouts. This assembly occurs spontaneously without any enzymatic ligation process and without the use of overhanging DNA as sticky ends. Instead, dimerizations of the PBI chromophores in the assembly are controlled by the DNA as a structural scaffold. Thereby, the PBI-driven assembly is fully reversible. Due to the fact that PBI dimerization does not occur in the single strand, the aggregates can be destroyed by thermal dehybridization of the DNA scaffold and reassembled by reannealing of the DNA construct. In view of the fact that PBI forms stable radical anions, the presented DNA architectures are not only interesting optical biomaterials, but are also promising materials for molecular electronics with DNA.}, author = {Menacher, Florian and Stepanenko, Vladimir and Würthner, Frank and Wagenknecht, Hans-Achim}, journal = {Chemistry – A European Journal}, keywords = {myown}, number = 24, pages = {6683–6688}, publisher = {WILEY-VCH Verlag}, title = {Assembly of DNA Triangles Mediated by Perylene Bisimide Caps}, volume = 17, year = 2011 }

  %0 Journal Article %1 CHEM:CHEM201100141 %A Menacher, Florian %A Stepanenko, Vladimir %A Würthner, Frank %A Wagenknecht, Hans-Achim %D 2011 %I WILEY-VCH Verlag %J Chemistry – A European Journal %N 24 %P 6683--6688 %R 10.1002/chem.201100141 %T Assembly of DNA Triangles Mediated by Perylene Bisimide Caps %U http://dx.doi.org/10.1002/chem.201100141 %V 17 %X Perylene bisimides (PBI) have been synthetically incorporated as caps onto a Y-shaped DNA triple strand. These PBI caps serve as “sticky” ends in the spontaneous assembly of larger DNA ensembles, linking the triangular DNA through stacking interactions. This, in turn, yields a hypsochromic shift in the absorption and a red shift in the fluorescence as characteristic optical readouts. This assembly occurs spontaneously without any enzymatic ligation process and without the use of overhanging DNA as sticky ends. Instead, dimerizations of the PBI chromophores in the assembly are controlled by the DNA as a structural scaffold. Thereby, the PBI-driven assembly is fully reversible. Due to the fact that PBI dimerization does not occur in the single strand, the aggregates can be destroyed by thermal dehybridization of the DNA scaffold and reassembled by reannealing of the DNA construct. In view of the fact that PBI forms stable radical anions, the presented DNA architectures are not only interesting optical biomaterials, but are also promising materials for molecular electronics with DNA.
• Photophysical and quantum chemical study on a J-aggregate forming perylene bisimide monomer. Ambrosek, David; Marciniak, Henning; Lochbrunner, Stefan; Tatchen, Jorg; Li, Xue-Qing; Würthner, Frank; Kuhn, Oliver. In Phys. Chem. Chem. Phys., 13(39), pp. 17649–17657. 2011.
  • [ Abstract ]
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  Perylene bisimides (PBIs) are excellent dyes and versatile building blocks for supramolecular structures. Only recently have PBIs been shown to depict absorption characteristics of J-aggregates. We apply electronic structure calculations and femtosecond pump-probe spectroscopy to the monomeric, bay-substituted building-block of a PBI aggregate in dichloromethane to investigate its electronically excited states in order to provide the ingredients for the description of excitons in the aggregates and their annihilation processes. The PBI S1 ? S0absorption spectrum and the S1 [rightward arrow] S0emission spectrum have been assigned based on time-dependent Density Functional Theory calculations for the geometry-optimized electronic ground state and excited state structures in the gas phase. The monomeric absorption spectrum contains a strong transition at 580 nm and a broad shoulder between 575-500 nm, both features are attributed to a vibrational progression with an effective vibrational mode of 1415 cm-1 whose major contributing vibrational normal modes are breathing modes of the perylene body. The effective vibrational mode of the emission spectrum is characterized by a frequency of 1369 cm-1, whose major contributing vibrational normal modes are characterized by perylene and phenol (bay-substituent) CH bendings. The Sn ? S1 excited state absorption spectrum is assigned based on Multi-Reference Configuration Interaction methodology. Here, we identify three transitions which give rise to two broad experimental features, one being located between 500 and 600 nm and the other one ranging from 650 to 750 nm.

  @article{C1CP21624D, abstract = {Perylene bisimides (PBIs) are excellent dyes and versatile building blocks for supramolecular structures. Only recently have PBIs been shown to depict absorption characteristics of J-aggregates. We apply electronic structure calculations and femtosecond pump-probe spectroscopy to the monomeric{,} bay-substituted building-block of a PBI aggregate in dichloromethane to investigate its electronically excited states in order to provide the ingredients for the description of excitons in the aggregates and their annihilation processes. The PBI S1 ? S0absorption spectrum and the S1 [rightward arrow] S0emission spectrum have been assigned based on time-dependent Density Functional Theory calculations for the geometry-optimized electronic ground state and excited state structures in the gas phase. The monomeric absorption spectrum contains a strong transition at 580 nm and a broad shoulder between 575-500 nm{,} both features are attributed to a vibrational progression with an effective vibrational mode of 1415 cm-1 whose major contributing vibrational normal modes are breathing modes of the perylene body. The effective vibrational mode of the emission spectrum is characterized by a frequency of 1369 cm-1{,} whose major contributing vibrational normal modes are characterized by perylene and phenol (bay-substituent) CH bendings. The Sn ? S1 excited state absorption spectrum is assigned based on Multi-Reference Configuration Interaction methodology. Here{,} we identify three transitions which give rise to two broad experimental features{,} one being located between 500 and 600 nm and the other one ranging from 650 to 750 nm.}, author = {Ambrosek, David and Marciniak, Henning and Lochbrunner, Stefan and Tatchen, Jorg and Li, Xue-Qing and Würthner, Frank and Kuhn, Oliver}, journal = {Phys. Chem. Chem. Phys.}, keywords = {myown}, number = 39, pages = {17649-17657}, publisher = {The Royal Society of Chemistry}, title = {Photophysical and quantum chemical study on a J-aggregate forming perylene bisimide monomer}, volume = 13, year = 2011 }

  %0 Journal Article %1 C1CP21624D %A Ambrosek, David %A Marciniak, Henning %A Lochbrunner, Stefan %A Tatchen, Jorg %A Li, Xue-Qing %A Würthner, Frank %A Kuhn, Oliver %D 2011 %I The Royal Society of Chemistry %J Phys. Chem. Chem. Phys. %N 39 %P 17649-17657 %R 10.1039/C1CP21624D %T Photophysical and quantum chemical study on a J-aggregate forming perylene bisimide monomer %U http://dx.doi.org/10.1039/C1CP21624D %V 13 %X Perylene bisimides (PBIs) are excellent dyes and versatile building blocks for supramolecular structures. Only recently have PBIs been shown to depict absorption characteristics of J-aggregates. We apply electronic structure calculations and femtosecond pump-probe spectroscopy to the monomeric, bay-substituted building-block of a PBI aggregate in dichloromethane to investigate its electronically excited states in order to provide the ingredients for the description of excitons in the aggregates and their annihilation processes. The PBI S1 ? S0absorption spectrum and the S1 [rightward arrow] S0emission spectrum have been assigned based on time-dependent Density Functional Theory calculations for the geometry-optimized electronic ground state and excited state structures in the gas phase. The monomeric absorption spectrum contains a strong transition at 580 nm and a broad shoulder between 575-500 nm, both features are attributed to a vibrational progression with an effective vibrational mode of 1415 cm-1 whose major contributing vibrational normal modes are breathing modes of the perylene body. The effective vibrational mode of the emission spectrum is characterized by a frequency of 1369 cm-1, whose major contributing vibrational normal modes are characterized by perylene and phenol (bay-substituent) CH bendings. The Sn ? S1 excited state absorption spectrum is assigned based on Multi-Reference Configuration Interaction methodology. Here, we identify three transitions which give rise to two broad experimental features, one being located between 500 and 600 nm and the other one ranging from 650 to 750 nm.
• Foldamer with a spiral perylene bisimide staircase aggregate structure. Dehm, Volker; Buchner, Michael; Seibt, Joachim; Engel, Volker; Würthner, Frank. In Chem. Sci., 2(11), pp. 2094–2100. 2011.
  • [ Abstract ]
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  Although the precise control of dye-dye interactions is known to be of fundamental importance to achieve desired functional properties in [small pi]-conjugated materials, there are only sporadic examples where precise structural control of dye-dye interactions could be achieved by the attachment of the chromophores to an oligomeric or polymeric backbone. In this edge article, we introduce an oligophenylene ethynylene/perylene bisimide (PBI) dye system which is conceived by the foldamer concept. The molecular design enables folding of the [small pi]-conjugated oligomer to give a geometrically well-defined [small pi]-stack of intrastrand PBI molecules. The synthesis of the foldamer and its characterization by MALDI-TOF mass spectrometry are described, and the average size is estimated by gel permeation chromatography (GPC) and diffusion ordered NMR spectroscopy (DOSY). The folding dynamics are demonstrated by ultraviolet/visible absorption and fluorescence emission spectroscopic studies as the folded and unfolded states possess distinct optical properties. Quantum dynamic considerations revealed a good agreement of the calculated aggregate absorption spectrum with those obtained experimentally.

  @article{C1SC00435B, abstract = {Although the precise control of dye-dye interactions is known to be of fundamental importance to achieve desired functional properties in [small pi]-conjugated materials{,} there are only sporadic examples where precise structural control of dye-dye interactions could be achieved by the attachment of the chromophores to an oligomeric or polymeric backbone. In this edge article{,} we introduce an oligophenylene ethynylene/perylene bisimide (PBI) dye system which is conceived by the foldamer concept. The molecular design enables folding of the [small pi]-conjugated oligomer to give a geometrically well-defined [small pi]-stack of intrastrand PBI molecules. The synthesis of the foldamer and its characterization by MALDI-TOF mass spectrometry are described{,} and the average size is estimated by gel permeation chromatography (GPC) and diffusion ordered NMR spectroscopy (DOSY). The folding dynamics are demonstrated by ultraviolet/visible absorption and fluorescence emission spectroscopic studies as the folded and unfolded states possess distinct optical properties. Quantum dynamic considerations revealed a good agreement of the calculated aggregate absorption spectrum with those obtained experimentally.}, author = {Dehm, Volker and Buchner, Michael and Seibt, Joachim and Engel, Volker and Würthner, Frank}, journal = {Chem. Sci.}, keywords = {myown}, number = 11, pages = {2094-2100}, publisher = {The Royal Society of Chemistry}, title = {Foldamer with a spiral perylene bisimide staircase aggregate structure}, volume = 2, year = 2011 }

  %0 Journal Article %1 C1SC00435B %A Dehm, Volker %A Buchner, Michael %A Seibt, Joachim %A Engel, Volker %A Würthner, Frank %D 2011 %I The Royal Society of Chemistry %J Chem. Sci. %N 11 %P 2094-2100 %R 10.1039/C1SC00435B %T Foldamer with a spiral perylene bisimide staircase aggregate structure %U http://dx.doi.org/10.1039/C1SC00435B %V 2 %X Although the precise control of dye-dye interactions is known to be of fundamental importance to achieve desired functional properties in [small pi]-conjugated materials, there are only sporadic examples where precise structural control of dye-dye interactions could be achieved by the attachment of the chromophores to an oligomeric or polymeric backbone. In this edge article, we introduce an oligophenylene ethynylene/perylene bisimide (PBI) dye system which is conceived by the foldamer concept. The molecular design enables folding of the [small pi]-conjugated oligomer to give a geometrically well-defined [small pi]-stack of intrastrand PBI molecules. The synthesis of the foldamer and its characterization by MALDI-TOF mass spectrometry are described, and the average size is estimated by gel permeation chromatography (GPC) and diffusion ordered NMR spectroscopy (DOSY). The folding dynamics are demonstrated by ultraviolet/visible absorption and fluorescence emission spectroscopic studies as the folded and unfolded states possess distinct optical properties. Quantum dynamic considerations revealed a good agreement of the calculated aggregate absorption spectrum with those obtained experimentally.
• Parallel Bulk-Heterojunction Solar Cell by Electrostatically Driven Phase Separation. Ojala, Antti; Bürckstümmer, Hannah; Stolte, Matthias; Sens, Rüdiger; Reichelt, Helmut; Erk, Peter; Hwang, Jaehyung; Hertel, Dirk; Meerholz, Klaus; Würthner, Frank. In Advanced Materials, 23(45), pp. 5398–5403. 2011.
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  @article{ADMA:ADMA201103167, author = {Ojala, Antti and Bürckstümmer, Hannah and Stolte, Matthias and Sens, Rüdiger and Reichelt, Helmut and Erk, Peter and Hwang, Jaehyung and Hertel, Dirk and Meerholz, Klaus and Würthner, Frank}, journal = {Advanced Materials}, keywords = {myown}, number = 45, pages = {5398–5403}, publisher = {WILEY-VCH Verlag}, title = {Parallel Bulk-Heterojunction Solar Cell by Electrostatically Driven Phase Separation}, volume = 23, year = 2011 }

  %0 Journal Article %1 ADMA:ADMA201103167 %A Ojala, Antti %A Bürckstümmer, Hannah %A Stolte, Matthias %A Sens, Rüdiger %A Reichelt, Helmut %A Erk, Peter %A Hwang, Jaehyung %A Hertel, Dirk %A Meerholz, Klaus %A Würthner, Frank %D 2011 %I WILEY-VCH Verlag %J Advanced Materials %N 45 %P 5398--5403 %R 10.1002/adma.201103167 %T Parallel Bulk-Heterojunction Solar Cell by Electrostatically Driven Phase Separation %U http://dx.doi.org/10.1002/adma.201103167 %V 23
• Synthesis and Characterization of Optical and Redox Properties of Bithiophene-Functionalized Diketopyrrolopyrrole Chromophores. Bürckstümmer, Hannah; Weissenstein, Annike; Bialas, David; Würthner, Frank. In The Journal of Organic Chemistry, 76(8), pp. 2426–2432. 2011.

  PMID: 21381701
  • [ Abstract ]
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  A series of six new 2,2′-bithiophene-functionalized diketopyrrolopyrrole (DPP) dyes 7a−f bearing different electron-donating and electron-withdrawing substituents at the terminal thiophene units was synthesized by palladium-catalyzed cross-coupling reactions. The to date unknown diiodinated DPP 2 and the corresponding boronic ester derivative 3 could be prepared in high yields, and these are shown to be versatile building blocks for the synthesis of DPP-based molecular materials by Negishi, Stille, and Suzuki coupling. The influence of the peripheral substituents on the optical and electrochemical properties of the present series of DPP dyes 7a−f were investigated by UV/vis and steady-state fluorescence spectroscopy and cyclic voltammetry, revealing an appreciable effect on the electronic nature of these dyes. The diamino-substituted DPP derivative 7e exhibits a strong absorption band reaching in the near-infrared (NIR) region, which is a highly desirable feature for application in organic photovoltaics.

  @article{doi:10.1021/jo2003117, abstract = {A series of six new 2,2′-bithiophene-functionalized diketopyrrolopyrrole (DPP) dyes 7a−f bearing different electron-donating and electron-withdrawing substituents at the terminal thiophene units was synthesized by palladium-catalyzed cross-coupling reactions. The to date unknown diiodinated DPP 2 and the corresponding boronic ester derivative 3 could be prepared in high yields, and these are shown to be versatile building blocks for the synthesis of DPP-based molecular materials by Negishi, Stille, and Suzuki coupling. The influence of the peripheral substituents on the optical and electrochemical properties of the present series of DPP dyes 7a−f were investigated by UV/vis and steady-state fluorescence spectroscopy and cyclic voltammetry, revealing an appreciable effect on the electronic nature of these dyes. The diamino-substituted DPP derivative 7e exhibits a strong absorption band reaching in the near-infrared (NIR) region, which is a highly desirable feature for application in organic photovoltaics.}, author = {Bürckstümmer, Hannah and Weissenstein, Annike and Bialas, David and Würthner, Frank}, journal = {The Journal of Organic Chemistry}, keywords = {myown}, note = {PMID: 21381701}, number = 8, pages = {2426-2432}, title = {Synthesis and Characterization of Optical and Redox Properties of Bithiophene-Functionalized Diketopyrrolopyrrole Chromophores}, volume = 76, year = 2011 }

  %0 Journal Article %1 doi:10.1021/jo2003117 %A Bürckstümmer, Hannah %A Weissenstein, Annike %A Bialas, David %A Würthner, Frank %D 2011 %J The Journal of Organic Chemistry %N 8 %P 2426-2432 %R 10.1021/jo2003117 %T Synthesis and Characterization of Optical and Redox Properties of Bithiophene-Functionalized Diketopyrrolopyrrole Chromophores %U http://dx.doi.org/10.1021/jo2003117 %V 76 %X A series of six new 2,2′-bithiophene-functionalized diketopyrrolopyrrole (DPP) dyes 7a−f bearing different electron-donating and electron-withdrawing substituents at the terminal thiophene units was synthesized by palladium-catalyzed cross-coupling reactions. The to date unknown diiodinated DPP 2 and the corresponding boronic ester derivative 3 could be prepared in high yields, and these are shown to be versatile building blocks for the synthesis of DPP-based molecular materials by Negishi, Stille, and Suzuki coupling. The influence of the peripheral substituents on the optical and electrochemical properties of the present series of DPP dyes 7a−f were investigated by UV/vis and steady-state fluorescence spectroscopy and cyclic voltammetry, revealing an appreciable effect on the electronic nature of these dyes. The diamino-substituted DPP derivative 7e exhibits a strong absorption band reaching in the near-infrared (NIR) region, which is a highly desirable feature for application in organic photovoltaics.
• Hydrogen-Bond-Directed Formation of Supramolecular Polymers Incorporating Head-to-Tail Oriented Dipolar Merocyanine Dyes. Schmidt, Ralf; Stolte, Matthias; Grüne, Matthias; Würthner, Frank. In Macromolecules, 44(10), pp. 3766–3776. 2011.
  • [ Abstract ]
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  A self-complementary Hamilton-receptor-functionalized merocyanine dye has been synthesized by incorporating a hydrogen bonding receptor site to the donor moiety of a merocyanine chromophore that bears a barbituric acid acceptor unit. The optical and electro-optical properties of monomeric dyes have been studied by UV–vis, fluorescence, and electro-optical absorption spectroscopy in chloroform, 1,4-dioxane, tetrahydrofuran, and dimethyl sulfoxide under dilute condition. The self-assembly properties of this self-complementary merocyanine in solution have been investigated by concentration- and temperature-dependent UV–vis and one- and two-dimensional NMR spectroscopy. These studies revealed that the present merocyanine dyes self-assemble in a head-to-tail fashion by forming six hydrogen bonds. The size of the assemblies in solution was determined by dynamic light scattering and diffusion-ordered spectroscopy NMR investigations. In nonpolar solvent mixtures at high concentrations, this merocyanine dye forms appreciably fluorescent gels (Φfl = 0.17) while the monomeric dye and self-assemblies in solution are only weakly fluorescent (Φfl = 0.07).

  @article{doi:10.1021/ma2004184, abstract = {A self-complementary Hamilton-receptor-functionalized merocyanine dye has been synthesized by incorporating a hydrogen bonding receptor site to the donor moiety of a merocyanine chromophore that bears a barbituric acid acceptor unit. The optical and electro-optical properties of monomeric dyes have been studied by UV–vis, fluorescence, and electro-optical absorption spectroscopy in chloroform, 1,4-dioxane, tetrahydrofuran, and dimethyl sulfoxide under dilute condition. The self-assembly properties of this self-complementary merocyanine in solution have been investigated by concentration- and temperature-dependent UV–vis and one- and two-dimensional NMR spectroscopy. These studies revealed that the present merocyanine dyes self-assemble in a head-to-tail fashion by forming six hydrogen bonds. The size of the assemblies in solution was determined by dynamic light scattering and diffusion-ordered spectroscopy NMR investigations. In nonpolar solvent mixtures at high concentrations, this merocyanine dye forms appreciably fluorescent gels (Φfl = 0.17) while the monomeric dye and self-assemblies in solution are only weakly fluorescent (Φfl = 0.07).}, author = {Schmidt, Ralf and Stolte, Matthias and Grüne, Matthias and Würthner, Frank}, journal = {Macromolecules}, keywords = {myown}, number = 10, pages = {3766-3776}, title = {Hydrogen-Bond-Directed Formation of Supramolecular Polymers Incorporating Head-to-Tail Oriented Dipolar Merocyanine Dyes}, volume = 44, year = 2011 }

  %0 Journal Article %1 doi:10.1021/ma2004184 %A Schmidt, Ralf %A Stolte, Matthias %A Grüne, Matthias %A Würthner, Frank %D 2011 %J Macromolecules %N 10 %P 3766-3776 %R 10.1021/ma2004184 %T Hydrogen-Bond-Directed Formation of Supramolecular Polymers Incorporating Head-to-Tail Oriented Dipolar Merocyanine Dyes %U http://dx.doi.org/10.1021/ma2004184 %V 44 %X A self-complementary Hamilton-receptor-functionalized merocyanine dye has been synthesized by incorporating a hydrogen bonding receptor site to the donor moiety of a merocyanine chromophore that bears a barbituric acid acceptor unit. The optical and electro-optical properties of monomeric dyes have been studied by UV–vis, fluorescence, and electro-optical absorption spectroscopy in chloroform, 1,4-dioxane, tetrahydrofuran, and dimethyl sulfoxide under dilute condition. The self-assembly properties of this self-complementary merocyanine in solution have been investigated by concentration- and temperature-dependent UV–vis and one- and two-dimensional NMR spectroscopy. These studies revealed that the present merocyanine dyes self-assemble in a head-to-tail fashion by forming six hydrogen bonds. The size of the assemblies in solution was determined by dynamic light scattering and diffusion-ordered spectroscopy NMR investigations. In nonpolar solvent mixtures at high concentrations, this merocyanine dye forms appreciably fluorescent gels (Φfl = 0.17) while the monomeric dye and self-assemblies in solution are only weakly fluorescent (Φfl = 0.07).
• A core-extended naphthalene diimide as a p-channel semiconductor. Suraru, Sabin-Lucian; Zschieschang, Ute; Klauk, Hagen; Würthner, Frank. In Chem. Commun., 47(41), pp. 11504–11506. 2011.
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  A novel naphthalene diimide with a fully conjugated, extended [small pi]-core was synthesized in a one-pot, two-step reaction. This organic semiconductor exhibits ambipolar transport properties with a large hole mobility of 0.56 cm2 V-1 s-1 and a current on/off ratio of 106 in bottom-gate, top-contact thin-film transistors prepared by vacuum deposition.

  @article{C1CC15144D, abstract = {A novel naphthalene diimide with a fully conjugated{,} extended [small pi]-core was synthesized in a one-pot{,} two-step reaction. This organic semiconductor exhibits ambipolar transport properties with a large hole mobility of 0.56 cm2 V-1 s-1 and a current on/off ratio of 106 in bottom-gate{,} top-contact thin-film transistors prepared by vacuum deposition.}, author = {Suraru, Sabin-Lucian and Zschieschang, Ute and Klauk, Hagen and Würthner, Frank}, journal = {Chem. Commun.}, keywords = {myown}, number = 41, pages = {11504-11506}, publisher = {The Royal Society of Chemistry}, title = {A core-extended naphthalene diimide as a p-channel semiconductor}, volume = 47, year = 2011 }

  %0 Journal Article %1 C1CC15144D %A Suraru, Sabin-Lucian %A Zschieschang, Ute %A Klauk, Hagen %A Würthner, Frank %D 2011 %I The Royal Society of Chemistry %J Chem. Commun. %N 41 %P 11504-11506 %R 10.1039/C1CC15144D %T A core-extended naphthalene diimide as a p-channel semiconductor %U http://dx.doi.org/10.1039/C1CC15144D %V 47 %X A novel naphthalene diimide with a fully conjugated, extended [small pi]-core was synthesized in a one-pot, two-step reaction. This organic semiconductor exhibits ambipolar transport properties with a large hole mobility of 0.56 cm2 V-1 s-1 and a current on/off ratio of 106 in bottom-gate, top-contact thin-film transistors prepared by vacuum deposition.
• Impact of core chirality on mesophase properties of perylene bisimides. Safont-Sempere, Marina M.; Stepanenko, Vladimir; Lehmann, Matthias; Würthner, Frank. In J. Mater. Chem., 21(20), pp. 7201–7209. 2011.
  • [ Abstract ]
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  The three-dimensional organisation of a racemic core-twisted perylene bisimide (PBI) 1 and its pure atropo-enantiomers ((P)-1 and (M)-1) are compared in the condensed state to elucidate the impact of core chirality in such materials. Our studies revealed distinctive differences in the condensed state properties of the racemic and enantiopure PBIs. While the racemic material forms a soft crystalline phase, the pure enantiomers (P)-1 and (M)-1 exhibit a smectic liquid crystalline mesophase of much lower viscosity as evidenced by differential scanning calorimetry (DSC), polarization optical microscopy (POM), X-ray diffraction of extruded samples and atomic force microscopy (AFM) investigations. Two different packing models for the condensed state of the racemate and its pure enantiomers have been proposed based on the observed mesophase properties and force field calculations.

  @article{C1JM10309A, abstract = {The three-dimensional organisation of a racemic core-twisted perylene bisimide (PBI) 1 and its pure atropo-enantiomers ((P)-1 and (M)-1) are compared in the condensed state to elucidate the impact of core chirality in such materials. Our studies revealed distinctive differences in the condensed state properties of the racemic and enantiopure PBIs. While the racemic material forms a soft crystalline phase{,} the pure enantiomers (P)-1 and (M)-1 exhibit a smectic liquid crystalline mesophase of much lower viscosity as evidenced by differential scanning calorimetry (DSC){,} polarization optical microscopy (POM){,} X-ray diffraction of extruded samples and atomic force microscopy (AFM) investigations. Two different packing models for the condensed state of the racemate and its pure enantiomers have been proposed based on the observed mesophase properties and force field calculations.}, author = {Safont-Sempere, Marina M. and Stepanenko, Vladimir and Lehmann, Matthias and Würthner, Frank}, journal = {J. Mater. Chem.}, keywords = {myown}, number = 20, pages = {7201-7209}, publisher = {The Royal Society of Chemistry}, title = {Impact of core chirality on mesophase properties of perylene bisimides}, volume = 21, year = 2011 }

  %0 Journal Article %1 C1JM10309A %A Safont-Sempere, Marina M. %A Stepanenko, Vladimir %A Lehmann, Matthias %A Würthner, Frank %D 2011 %I The Royal Society of Chemistry %J J. Mater. Chem. %N 20 %P 7201-7209 %R 10.1039/C1JM10309A %T Impact of core chirality on mesophase properties of perylene bisimides %U http://dx.doi.org/10.1039/C1JM10309A %V 21 %X The three-dimensional organisation of a racemic core-twisted perylene bisimide (PBI) 1 and its pure atropo-enantiomers ((P)-1 and (M)-1) are compared in the condensed state to elucidate the impact of core chirality in such materials. Our studies revealed distinctive differences in the condensed state properties of the racemic and enantiopure PBIs. While the racemic material forms a soft crystalline phase, the pure enantiomers (P)-1 and (M)-1 exhibit a smectic liquid crystalline mesophase of much lower viscosity as evidenced by differential scanning calorimetry (DSC), polarization optical microscopy (POM), X-ray diffraction of extruded samples and atomic force microscopy (AFM) investigations. Two different packing models for the condensed state of the racemate and its pure enantiomers have been proposed based on the observed mesophase properties and force field calculations.
• Computational and spectroscopic studies of organic mixed-valence compounds: where is the charge?. Kaupp, Martin; Renz, Manuel; Parthey, Matthias; Stolte, Matthias; Würthner, Frank; Lambert, Christoph. In Phys. Chem. Chem. Phys., 13(38), pp. 16973–16986. 2011.
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  This article discusses recent progress by a combination of spectroscopy and quantum-chemical calculations in classifying and characterizing organic mixed-valence systems in terms of their localized vs. delocalized character. A recently developed quantum-chemical protocol based on non-standard hybrid functionals and continuum solvent models is evaluated for an extended set of mixed-valence bis-triarylamine radical cations, augmented by unsymmetrical neutral triarylamine-perchlorotriphenylmethyl radicals. It turns out that the protocol is able to provide a successful assignment to class II or class III Robin-Day behavior and gives quite accurate ground- and excited-state properties for the radical cations. The limits of the protocol are probed by the anthracene-bridged system 8, where it is suspected that specific solute-solvent interactions are important and not covered by the continuum solvent model. Intervalence charge-transfer excitation energies for the neutral unsymmetrical radicals are systematically overestimated, but dipole moments and a number of other properties are obtained accurately by the protocol.

  @article{C1CP21772K, abstract = {This article discusses recent progress by a combination of spectroscopy and quantum-chemical calculations in classifying and characterizing organic mixed-valence systems in terms of their localized vs. delocalized character. A recently developed quantum-chemical protocol based on non-standard hybrid functionals and continuum solvent models is evaluated for an extended set of mixed-valence bis-triarylamine radical cations{,} augmented by unsymmetrical neutral triarylamine-perchlorotriphenylmethyl radicals. It turns out that the protocol is able to provide a successful assignment to class II or class III Robin-Day behavior and gives quite accurate ground- and excited-state properties for the radical cations. The limits of the protocol are probed by the anthracene-bridged system 8{,} where it is suspected that specific solute-solvent interactions are important and not covered by the continuum solvent model. Intervalence charge-transfer excitation energies for the neutral unsymmetrical radicals are systematically overestimated{,} but dipole moments and a number of other properties are obtained accurately by the protocol.}, author = {Kaupp, Martin and Renz, Manuel and Parthey, Matthias and Stolte, Matthias and Würthner, Frank and Lambert, Christoph}, journal = {Phys. Chem. Chem. Phys.}, keywords = {myown}, number = 38, pages = {16973-16986}, publisher = {The Royal Society of Chemistry}, title = {Computational and spectroscopic studies of organic mixed-valence compounds: where is the charge?}, volume = 13, year = 2011 }

  %0 Journal Article %1 C1CP21772K %A Kaupp, Martin %A Renz, Manuel %A Parthey, Matthias %A Stolte, Matthias %A Würthner, Frank %A Lambert, Christoph %D 2011 %I The Royal Society of Chemistry %J Phys. Chem. Chem. Phys. %N 38 %P 16973-16986 %R 10.1039/C1CP21772K %T Computational and spectroscopic studies of organic mixed-valence compounds: where is the charge? %U http://dx.doi.org/10.1039/C1CP21772K %V 13 %X This article discusses recent progress by a combination of spectroscopy and quantum-chemical calculations in classifying and characterizing organic mixed-valence systems in terms of their localized vs. delocalized character. A recently developed quantum-chemical protocol based on non-standard hybrid functionals and continuum solvent models is evaluated for an extended set of mixed-valence bis-triarylamine radical cations, augmented by unsymmetrical neutral triarylamine-perchlorotriphenylmethyl radicals. It turns out that the protocol is able to provide a successful assignment to class II or class III Robin-Day behavior and gives quite accurate ground- and excited-state properties for the radical cations. The limits of the protocol are probed by the anthracene-bridged system 8, where it is suspected that specific solute-solvent interactions are important and not covered by the continuum solvent model. Intervalence charge-transfer excitation energies for the neutral unsymmetrical radicals are systematically overestimated, but dipole moments and a number of other properties are obtained accurately by the protocol.
• Optimized solution-processed merocyanine:PCBM organic bulk heterojunction solar cell. Kronenberg, Nils M.; Bürckstümmer, Hannah; Deppisch, Manuela; Würthner, Frank; Meerholz, Klaus. In Journal of Photonics for Energy, 1, pp. 1 – 1 . 2011.
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  We present the in-depth investigation of solution-processed bulk-heterojunction solar cells based on the merocyanine dye MD304 as a donor in combination with the soluble fullerene derivative [6,6]-phenyl-C₆₁-butyric acid methyl ester (PCBM) as acceptor. The optimized MD304:PCBM devices exhibit an external quantum efficiency of ca. 50%, and a power conversion efficiency of up to 2.1% under standard illumination and 2.7% under reduced illumination intensities. Because of the strongly dipolar character of merocyanine dyes the bulk material features a relatively large dielectric constant, which is beneficial for charge transport and reduced carrier recombination. This somewhat compensates the limited hole mobility of the dipolar merocyanine.

  @article{kronenberg2011optimized, abstract = {We present the in-depth investigation of solution-processed bulk-heterojunction solar cells based on the merocyanine dye MD304 as a donor in combination with the soluble fullerene derivative [6,6]-phenyl-C₆₁-butyric acid methyl ester (PCBM) as acceptor. The optimized MD304:PCBM devices exhibit an external quantum efficiency of ca. 50%, and a power conversion efficiency of up to 2.1% under standard illumination and 2.7% under reduced illumination intensities. Because of the strongly dipolar character of merocyanine dyes the bulk material features a relatively large dielectric constant, which is beneficial for charge transport and reduced carrier recombination. This somewhat compensates the limited hole mobility of the dipolar merocyanine.}, author = {Kronenberg, Nils M. and Bürckstümmer, Hannah and Deppisch, Manuela and Würthner, Frank and Meerholz, Klaus}, journal = {Journal of Photonics for Energy}, keywords = {myown}, pages = {1 - 1 - 8}, title = {Optimized solution-processed merocyanine:PCBM organic bulk heterojunction solar cell}, volume = 1, year = 2011 }

  %0 Journal Article %1 kronenberg2011optimized %A Kronenberg, Nils M. %A Bürckstümmer, Hannah %A Deppisch, Manuela %A Würthner, Frank %A Meerholz, Klaus %D 2011 %J Journal of Photonics for Energy %P 1 - 1 - 8 %R 10.1117/1.3528043 %T Optimized solution-processed merocyanine:PCBM organic bulk heterojunction solar cell %U http://dx.doi.org/10.1117/1.3528043 %V 1 %X We present the in-depth investigation of solution-processed bulk-heterojunction solar cells based on the merocyanine dye MD304 as a donor in combination with the soluble fullerene derivative [6,6]-phenyl-C₆₁-butyric acid methyl ester (PCBM) as acceptor. The optimized MD304:PCBM devices exhibit an external quantum efficiency of ca. 50%, and a power conversion efficiency of up to 2.1% under standard illumination and 2.7% under reduced illumination intensities. Because of the strongly dipolar character of merocyanine dyes the bulk material features a relatively large dielectric constant, which is beneficial for charge transport and reduced carrier recombination. This somewhat compensates the limited hole mobility of the dipolar merocyanine.
• Naphthalene and perylene diimides for organic transistors. Würthner, Frank; Stolte, Matthias. In Chem. Commun., 47(18), pp. 5109–5115. 2011.
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  The development of ambient stable organic n-channel semiconductor molecules for thin-film transistors has experienced a tremendous impetus in the last decade to close the gap in performance in comparison to that of their p-channel counterparts. Especially naphthalene and perylene tetracarboxylic diimides (NDI and PDI) have shown to be the most valuable building blocks to achieve this challenging goal and to gain insight into the molecular structure-transistor performance relationship. Remaining challenges and new emerging research fields for these n-type semiconductors are the optimization of their deposition on flexible substrates, the control of their long term ambient stability and their implementation in complementary transistor circuits, display and sensor devices.

  @article{C1CC10321K, abstract = {The development of ambient stable organic n-channel semiconductor molecules for thin-film transistors has experienced a tremendous impetus in the last decade to close the gap in performance in comparison to that of their p-channel counterparts. Especially naphthalene and perylene tetracarboxylic diimides (NDI and PDI) have shown to be the most valuable building blocks to achieve this challenging goal and to gain insight into the molecular structure-transistor performance relationship. Remaining challenges and new emerging research fields for these n-type semiconductors are the optimization of their deposition on flexible substrates{,} the control of their long term ambient stability and their implementation in complementary transistor circuits{,} display and sensor devices.}, author = {Würthner, Frank and Stolte, Matthias}, journal = {Chem. Commun.}, keywords = {myown}, number = 18, pages = {5109-5115}, publisher = {The Royal Society of Chemistry}, title = {Naphthalene and perylene diimides for organic transistors}, volume = 47, year = 2011 }

  %0 Journal Article %1 C1CC10321K %A Würthner, Frank %A Stolte, Matthias %D 2011 %I The Royal Society of Chemistry %J Chem. Commun. %N 18 %P 5109-5115 %R 10.1039/C1CC10321K %T Naphthalene and perylene diimides for organic transistors %U http://dx.doi.org/10.1039/C1CC10321K %V 47 %X The development of ambient stable organic n-channel semiconductor molecules for thin-film transistors has experienced a tremendous impetus in the last decade to close the gap in performance in comparison to that of their p-channel counterparts. Especially naphthalene and perylene tetracarboxylic diimides (NDI and PDI) have shown to be the most valuable building blocks to achieve this challenging goal and to gain insight into the molecular structure-transistor performance relationship. Remaining challenges and new emerging research fields for these n-type semiconductors are the optimization of their deposition on flexible substrates, the control of their long term ambient stability and their implementation in complementary transistor circuits, display and sensor devices.
• Columnar Mesophases Based on Zinc Chlorophyll Derivatives Functionalized with Peripheral Dendron Wedges. Sengupta, Sanchita; Uemura, Shinobu; Patwardhan, Sameer; Huber, Valerie; Grozema, Ferdinand C.; Siebbeles, Laurens D. A.; Baumeister, Ute; Würthner, Frank. In Chemistry – A European Journal, 17(19), pp. 5300–5310. 2011.
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  A chlorophyll derivative with a central zinc ion, a methoxy functionality at its 31-position, and functionalized with a second-generation dendron (3,4-3,4,5)12G2-CH2OH at its 172-position was synthesized starting from natural chlorophyll a (Chl a). This compound exhibits liquid crystalline (LC) behavior and its mesomorphic properties have been characterized by differential scanning calorimetry (DSC), polarisation optical microscopy (POM), powder X-ray diffraction (XRD), and scanning probe microscopy (SPM). A combination of powder XRD, high resolution scanning tunneling microscopy (STM), and atomic force microscopy (AFM) experiments revealed the formation of nano-segregated well-ordered columnar tubular superstructures consisting of about five molecules in the column stratum. These self-assembled columns are further self-organized into a two-dimensional oblique unit cell lattice. Semiconducting behavior of this compound has been studied by pulse-radiolysis time-resolved microwave conductivity (PR-TRMC) method and charge carrier mobility values of ∼10−2 cm2 V−1 s−1 are observed. Such organized columnar superstructures constructed from semisynthetic zinc chlorins are reminiscent of the tubular organization of the bacteriochlorophyll dyes in the light-harvesting chlorosomal antennae of green sulphur bacteria.

  @article{CHEM:CHEM201002659, abstract = {A chlorophyll derivative with a central zinc ion, a methoxy functionality at its 31-position, and functionalized with a second-generation dendron (3,4-3,4,5)12G2-CH2OH at its 172-position was synthesized starting from natural chlorophyll a (Chl a). This compound exhibits liquid crystalline (LC) behavior and its mesomorphic properties have been characterized by differential scanning calorimetry (DSC), polarisation optical microscopy (POM), powder X-ray diffraction (XRD), and scanning probe microscopy (SPM). A combination of powder XRD, high resolution scanning tunneling microscopy (STM), and atomic force microscopy (AFM) experiments revealed the formation of nano-segregated well-ordered columnar tubular superstructures consisting of about five molecules in the column stratum. These self-assembled columns are further self-organized into a two-dimensional oblique unit cell lattice. Semiconducting behavior of this compound has been studied by pulse-radiolysis time-resolved microwave conductivity (PR-TRMC) method and charge carrier mobility values of ∼10−2 cm2 V−1 s−1 are observed. Such organized columnar superstructures constructed from semisynthetic zinc chlorins are reminiscent of the tubular organization of the bacteriochlorophyll dyes in the light-harvesting chlorosomal antennae of green sulphur bacteria.}, author = {Sengupta, Sanchita and Uemura, Shinobu and Patwardhan, Sameer and Huber, Valerie and Grozema, Ferdinand C. and Siebbeles, Laurens D. A. and Baumeister, Ute and Würthner, Frank}, journal = {Chemistry – A European Journal}, keywords = {myown}, number = 19, pages = {5300–5310}, publisher = {WILEY-VCH Verlag}, title = {Columnar Mesophases Based on Zinc Chlorophyll Derivatives Functionalized with Peripheral Dendron Wedges}, volume = 17, year = 2011 }

  %0 Journal Article %1 CHEM:CHEM201002659 %A Sengupta, Sanchita %A Uemura, Shinobu %A Patwardhan, Sameer %A Huber, Valerie %A Grozema, Ferdinand C. %A Siebbeles, Laurens D. A. %A Baumeister, Ute %A Würthner, Frank %D 2011 %I WILEY-VCH Verlag %J Chemistry – A European Journal %N 19 %P 5300--5310 %R 10.1002/chem.201002659 %T Columnar Mesophases Based on Zinc Chlorophyll Derivatives Functionalized with Peripheral Dendron Wedges %U http://dx.doi.org/10.1002/chem.201002659 %V 17 %X A chlorophyll derivative with a central zinc ion, a methoxy functionality at its 31-position, and functionalized with a second-generation dendron (3,4-3,4,5)12G2-CH2OH at its 172-position was synthesized starting from natural chlorophyll a (Chl a). This compound exhibits liquid crystalline (LC) behavior and its mesomorphic properties have been characterized by differential scanning calorimetry (DSC), polarisation optical microscopy (POM), powder X-ray diffraction (XRD), and scanning probe microscopy (SPM). A combination of powder XRD, high resolution scanning tunneling microscopy (STM), and atomic force microscopy (AFM) experiments revealed the formation of nano-segregated well-ordered columnar tubular superstructures consisting of about five molecules in the column stratum. These self-assembled columns are further self-organized into a two-dimensional oblique unit cell lattice. Semiconducting behavior of this compound has been studied by pulse-radiolysis time-resolved microwave conductivity (PR-TRMC) method and charge carrier mobility values of ∼10−2 cm2 V−1 s−1 are observed. Such organized columnar superstructures constructed from semisynthetic zinc chlorins are reminiscent of the tubular organization of the bacteriochlorophyll dyes in the light-harvesting chlorosomal antennae of green sulphur bacteria.
• J-Aggregates: From Serendipitous Discovery to Supramolecular Engineering of Functional Dye Materials. Würthner, Frank; Kaiser, Theo E.; Saha-Möller, Chantu R. In Angew. Chem. Int. Ed., 50(15), pp. 3376–3410. 2011.
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  J-aggregates are of significant interest for organic materials conceived by supramolecular approaches. Their discovery in the 1930s represents one of the most important milestones in dye chemistry as well as the germination of supramolecular chemistry. The intriguing optical properties of J-aggregates (in particular, very narrow red-shifted absorption bands with respect to those of the monomer and their ability to delocalize and migrate excitons) as well as their prospect for applications have motivated scientists to become involved in this field, and numerous contributions have been published. This Review provides an overview on the J-aggregates of a broad variety of dyes (including cyanines, porphyrins, phthalocyanines, and perylene bisimides) created by using supramolecular construction principles, and discusses their optical and photophysical properties as well as their potential applications. Thus, this Review is intended to be of interest to the supramolecular, photochemistry, and materials science communities.

  @article{ANIE:ANIE201002307, abstract = {J-aggregates are of significant interest for organic materials conceived by supramolecular approaches. Their discovery in the 1930s represents one of the most important milestones in dye chemistry as well as the germination of supramolecular chemistry. The intriguing optical properties of J-aggregates (in particular, very narrow red-shifted absorption bands with respect to those of the monomer and their ability to delocalize and migrate excitons) as well as their prospect for applications have motivated scientists to become involved in this field, and numerous contributions have been published. This Review provides an overview on the J-aggregates of a broad variety of dyes (including cyanines, porphyrins, phthalocyanines, and perylene bisimides) created by using supramolecular construction principles, and discusses their optical and photophysical properties as well as their potential applications. Thus, this Review is intended to be of interest to the supramolecular, photochemistry, and materials science communities.}, author = {Würthner, Frank and Kaiser, Theo E. and Saha-Möller, Chantu R.}, journal = {Angew. Chem. Int. Ed.}, keywords = {myown}, number = 15, pages = {3376–3410}, publisher = {WILEY-VCH Verlag}, title = {J-Aggregates: From Serendipitous Discovery to Supramolecular Engineering of Functional Dye Materials}, volume = 50, year = 2011 }

  %0 Journal Article %1 ANIE:ANIE201002307 %A Würthner, Frank %A Kaiser, Theo E. %A Saha-Möller, Chantu R. %D 2011 %I WILEY-VCH Verlag %J Angew. Chem. Int. Ed. %N 15 %P 3376--3410 %R 10.1002/anie.201002307 %T J-Aggregates: From Serendipitous Discovery to Supramolecular Engineering of Functional Dye Materials %U http://dx.doi.org/10.1002/anie.201002307 %V 50 %X J-aggregates are of significant interest for organic materials conceived by supramolecular approaches. Their discovery in the 1930s represents one of the most important milestones in dye chemistry as well as the germination of supramolecular chemistry. The intriguing optical properties of J-aggregates (in particular, very narrow red-shifted absorption bands with respect to those of the monomer and their ability to delocalize and migrate excitons) as well as their prospect for applications have motivated scientists to become involved in this field, and numerous contributions have been published. This Review provides an overview on the J-aggregates of a broad variety of dyes (including cyanines, porphyrins, phthalocyanines, and perylene bisimides) created by using supramolecular construction principles, and discusses their optical and photophysical properties as well as their potential applications. Thus, this Review is intended to be of interest to the supramolecular, photochemistry, and materials science communities.

• Systems Chemistry Approach in Organic Photovoltaics. Würthner, Frank; Meerholz, Klaus. In Chemistry – A European Journal, 16(31), pp. 9366–9373. 2010.
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  The common approach in organic materials science is dominated by the perception that the properties of the bulk materials are virtually determined by the properties of the molecular building blocks. In this Concept Article, we advocate for taking into account supramolecular organization principles for all kinds of organic solid-state materials, irrespective of them being crystalline, liquid crystalline, or amorphous, and discuss a showcase example, that is, the utilization of merocyanine dyes as p-type organic semiconductors in bulk heterojunction (BHJ) solar cells. Despite their extraordinarily large dipole moments, which are considered to be detrimental for efficient charge carrier transport, BHJ organic photovoltaic materials of these dyes with fullerenes have reached remarkable power conversion efficiencies of meanwhile nearly 5 %. These at the first glance contradictory properties are, however, well-understandable on the systems chemistry level.

  @article{CHEM:CHEM201001153, abstract = {The common approach in organic materials science is dominated by the perception that the properties of the bulk materials are virtually determined by the properties of the molecular building blocks. In this Concept Article, we advocate for taking into account supramolecular organization principles for all kinds of organic solid-state materials, irrespective of them being crystalline, liquid crystalline, or amorphous, and discuss a showcase example, that is, the utilization of merocyanine dyes as p-type organic semiconductors in bulk heterojunction (BHJ) solar cells. Despite their extraordinarily large dipole moments, which are considered to be detrimental for efficient charge carrier transport, BHJ organic photovoltaic materials of these dyes with fullerenes have reached remarkable power conversion efficiencies of meanwhile nearly 5 %. These at the first glance contradictory properties are, however, well-understandable on the systems chemistry level.}, author = {Würthner, Frank and Meerholz, Klaus}, journal = {Chemistry – A European Journal}, keywords = {myown}, number = 31, pages = {9366–9373}, publisher = {WILEY-VCH Verlag}, title = {Systems Chemistry Approach in Organic Photovoltaics}, volume = 16, year = 2010 }

  %0 Journal Article %1 CHEM:CHEM201001153 %A Würthner, Frank %A Meerholz, Klaus %D 2010 %I WILEY-VCH Verlag %J Chemistry – A European Journal %N 31 %P 9366--9373 %R 10.1002/chem.201001153 %T Systems Chemistry Approach in Organic Photovoltaics %U http://dx.doi.org/10.1002/chem.201001153 %V 16 %X The common approach in organic materials science is dominated by the perception that the properties of the bulk materials are virtually determined by the properties of the molecular building blocks. In this Concept Article, we advocate for taking into account supramolecular organization principles for all kinds of organic solid-state materials, irrespective of them being crystalline, liquid crystalline, or amorphous, and discuss a showcase example, that is, the utilization of merocyanine dyes as p-type organic semiconductors in bulk heterojunction (BHJ) solar cells. Despite their extraordinarily large dipole moments, which are considered to be detrimental for efficient charge carrier transport, BHJ organic photovoltaic materials of these dyes with fullerenes have reached remarkable power conversion efficiencies of meanwhile nearly 5 %. These at the first glance contradictory properties are, however, well-understandable on the systems chemistry level.
• Near-Infrared Absorbing Merocyanine Dyes for Bulk Heterojunction Solar Cells. Bürckstümmer, Hannah; Kronenberg, Nils M.; Meerholz, Klaus; Würthner, Frank. In Organic Letters, 12(16), pp. 3666–3669. 2010.

  PMID: 20704411
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  A series of near-infrared absorbing merocyanine dyes bearing the strong electron-accepting 2-oxo-5-dicyanomethylene-pyrrolidine unit was synthesized and applied in combination with PC61BM and PC71BM in solution-processed photoactive layers of bulk heterojunction solar cells, exhibiting a remarkable performance range with power conversion efficiencies from 0.01\% to 1.00\%.

  @article{doi:10.1021/ol101492q, abstract = {A series of near-infrared absorbing merocyanine dyes bearing the strong electron-accepting 2-oxo-5-dicyanomethylene-pyrrolidine unit was synthesized and applied in combination with PC61BM and PC71BM in solution-processed photoactive layers of bulk heterojunction solar cells, exhibiting a remarkable performance range with power conversion efficiencies from 0.01\% to 1.00\%.}, author = {Bürckstümmer, Hannah and Kronenberg, Nils M. and Meerholz, Klaus and Würthner, Frank}, journal = {Organic Letters}, keywords = {myown}, note = {PMID: 20704411}, number = 16, pages = {3666-3669}, title = {Near-Infrared Absorbing Merocyanine Dyes for Bulk Heterojunction Solar Cells}, volume = 12, year = 2010 }

  %0 Journal Article %1 doi:10.1021/ol101492q %A Bürckstümmer, Hannah %A Kronenberg, Nils M. %A Meerholz, Klaus %A Würthner, Frank %D 2010 %J Organic Letters %N 16 %P 3666-3669 %R 10.1021/ol101492q %T Near-Infrared Absorbing Merocyanine Dyes for Bulk Heterojunction Solar Cells %U http://dx.doi.org/10.1021/ol101492q %V 12 %X A series of near-infrared absorbing merocyanine dyes bearing the strong electron-accepting 2-oxo-5-dicyanomethylene-pyrrolidine unit was synthesized and applied in combination with PC61BM and PC71BM in solution-processed photoactive layers of bulk heterojunction solar cells, exhibiting a remarkable performance range with power conversion efficiencies from 0.01\% to 1.00\%.
• Theoretical Study of the Optical Properties of Artificial Self-Assembled Zinc Chlorins. Patwardhan, Sameer; Sengupta, Sanchita; Würthner, Frank; Siebbeles, Laurens D. A.; Grozema, Ferdinand. In J. Phys. Chem. C., 114(48), pp. 20834–20842. 2010.
  • [ Abstract ]
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  The optical properties of the supramolecular aggregates formed by semisynthetic 31-methoxy zinc chlorins were studied theoretically using an exciton theory description. The exciton coupling between the chromophores was calculated using a transition density formalism, making it possible to distinguish stereochemical differences that arise from the facial orientations of the chiral zinc chlorin molecules in the aggregate. It is shown that the precise stereochemical orientation of the molecules inside the stack strongly influences the observed optical properties. These calculations point to a structure with alternating twist angles along the stack, suggesting a different orientation of neighboring molecules. This study is the first step to systematically investigate the optical properties of chlorophyll aggregates, to unveil the supramolecular organization, and to correctly describe the energy transport processes.

  @article{doi:10.1021/jp107184y, abstract = {The optical properties of the supramolecular aggregates formed by semisynthetic 31-methoxy zinc chlorins were studied theoretically using an exciton theory description. The exciton coupling between the chromophores was calculated using a transition density formalism, making it possible to distinguish stereochemical differences that arise from the facial orientations of the chiral zinc chlorin molecules in the aggregate. It is shown that the precise stereochemical orientation of the molecules inside the stack strongly influences the observed optical properties. These calculations point to a structure with alternating twist angles along the stack, suggesting a different orientation of neighboring molecules. This study is the first step to systematically investigate the optical properties of chlorophyll aggregates, to unveil the supramolecular organization, and to correctly describe the energy transport processes.}, author = {Patwardhan, Sameer and Sengupta, Sanchita and Würthner, Frank and Siebbeles, Laurens D. A. and Grozema, Ferdinand}, journal = {J. Phys. Chem. C.}, keywords = {myown}, number = 48, pages = {20834-20842}, title = {Theoretical Study of the Optical Properties of Artificial Self-Assembled Zinc Chlorins}, volume = 114, year = 2010 }

  %0 Journal Article %1 doi:10.1021/jp107184y %A Patwardhan, Sameer %A Sengupta, Sanchita %A Würthner, Frank %A Siebbeles, Laurens D. A. %A Grozema, Ferdinand %D 2010 %J J. Phys. Chem. C. %N 48 %P 20834-20842 %R 10.1021/jp107184y %T Theoretical Study of the Optical Properties of Artificial Self-Assembled Zinc Chlorins %U http://dx.doi.org/10.1021/jp107184y %V 114 %X The optical properties of the supramolecular aggregates formed by semisynthetic 31-methoxy zinc chlorins were studied theoretically using an exciton theory description. The exciton coupling between the chromophores was calculated using a transition density formalism, making it possible to distinguish stereochemical differences that arise from the facial orientations of the chiral zinc chlorin molecules in the aggregate. It is shown that the precise stereochemical orientation of the molecules inside the stack strongly influences the observed optical properties. These calculations point to a structure with alternating twist angles along the stack, suggesting a different orientation of neighboring molecules. This study is the first step to systematically investigate the optical properties of chlorophyll aggregates, to unveil the supramolecular organization, and to correctly describe the energy transport processes.
• Polymer Glass Transitions Switch Electron Transfer in Individual Molecules. Siekierzycka, Joanna R.; Hippius, Catharina; Würthner, Frank; Williams, René M.; Brouwer, Albert M. In J. Am. Chem. Soc., 132(4), pp. 1240–1242. 2010.

  PMID: 20050649
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  Essentially complete photoinduced electron transfer quenching of the fluorescence of a perylene−calixarene compound occurs in poly(methyl acrylate) and poly(vinyl acetate) above their glass transition temperatures (Tg), but the fluorescence is completely recovered upon cooling the polymer matrix to a few degrees below the Tg. The switching can be observed in an on/off fashion at the level of individual molecules.

  @article{doi:10.1021/ja905667c, abstract = {Essentially complete photoinduced electron transfer quenching of the fluorescence of a perylene−calixarene compound occurs in poly(methyl acrylate) and poly(vinyl acetate) above their glass transition temperatures (Tg), but the fluorescence is completely recovered upon cooling the polymer matrix to a few degrees below the Tg. The switching can be observed in an on/off fashion at the level of individual molecules.}, author = {Siekierzycka, Joanna R. and Hippius, Catharina and Würthner, Frank and Williams, René M. and Brouwer, Albert M.}, journal = {J. Am. Chem. Soc.}, keywords = {myown}, note = {PMID: 20050649}, number = 4, pages = {1240-1242}, title = {Polymer Glass Transitions Switch Electron Transfer in Individual Molecules}, volume = 132, year = 2010 }

  %0 Journal Article %1 doi:10.1021/ja905667c %A Siekierzycka, Joanna R. %A Hippius, Catharina %A Würthner, Frank %A Williams, René M. %A Brouwer, Albert M. %D 2010 %J J. Am. Chem. Soc. %N 4 %P 1240-1242 %R 10.1021/ja905667c %T Polymer Glass Transitions Switch Electron Transfer in Individual Molecules %U http://dx.doi.org/10.1021/ja905667c %V 132 %X Essentially complete photoinduced electron transfer quenching of the fluorescence of a perylene−calixarene compound occurs in poly(methyl acrylate) and poly(vinyl acetate) above their glass transition temperatures (Tg), but the fluorescence is completely recovered upon cooling the polymer matrix to a few degrees below the Tg. The switching can be observed in an on/off fashion at the level of individual molecules.
• A Crystal-Engineered Hydrogen-Bonded Octachloroperylene Diimide with a Twisted Core: An n-Channel Organic Semiconductor. Gsänger, Marcel; Oh, Joon Hak; Könemann, Martin; Höffken, Hans Wolfgang; Krause, Ana-Maria; Bao, Zhenan; Würthner, Frank. In Angew. Chem. Int. Ed., 49(4), pp. 740–743. 2010.
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  @article{ANIE:ANIE200904215, author = {Gsänger, Marcel and Oh, Joon Hak and Könemann, Martin and Höffken, Hans Wolfgang and Krause, Ana-Maria and Bao, Zhenan and Würthner, Frank}, journal = {Angew. Chem. Int. Ed.}, keywords = {myown}, number = 4, pages = {740–743}, publisher = {WILEY-VCH Verlag}, title = {A Crystal-Engineered Hydrogen-Bonded Octachloroperylene Diimide with a Twisted Core: An n-Channel Organic Semiconductor}, volume = 49, year = 2010 }

  %0 Journal Article %1 ANIE:ANIE200904215 %A Gsänger, Marcel %A Oh, Joon Hak %A Könemann, Martin %A Höffken, Hans Wolfgang %A Krause, Ana-Maria %A Bao, Zhenan %A Würthner, Frank %D 2010 %I WILEY-VCH Verlag %J Angew. Chem. Int. Ed. %N 4 %P 740--743 %R 10.1002/anie.200904215 %T A Crystal-Engineered Hydrogen-Bonded Octachloroperylene Diimide with a Twisted Core: An n-Channel Organic Semiconductor %U http://dx.doi.org/10.1002/anie.200904215 %V 49
• Solvent- and Guest-Responsive Self-Assembly of Hamilton Receptor Tethered Bis(merocyanine) Dyes. Schmidt, Ralf; Uemura, Shinobu; Würthner, Frank. In Chemistry – A European Journal, 16(46), pp. 13706–13715. 2010.
  • [ Abstract ]
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  A novel supramolecular building block (8) that consists of a Hamilton receptor and two merocyanine dyes has been synthesized, and the self-assembly based on orthogonal hydrogen bonding and dipolar interactions has been studied in detail. Different self-assembled species, including oligomers, polymers, and inverted micelles could be observed upon variation of the solvent polarity and the concentration. Moreover, this system is highly responsive toward molecular stimuli such as merocyanine molecules with the barbituric acid motif that are bound by the Hamilton receptors. Detailed UV/Vis absorption studies provided insight into isodesmic or cooperative steps during the self-assembly of 8 into different species. The size of the aggregates in solution and the morphology on substrates have been explored by a combination of dynamic light scattering (DLS), atomic force microscopy (AFM), and TEM investigations.

  @article{CHEM:CHEM201002159, abstract = {A novel supramolecular building block (8) that consists of a Hamilton receptor and two merocyanine dyes has been synthesized, and the self-assembly based on orthogonal hydrogen bonding and dipolar interactions has been studied in detail. Different self-assembled species, including oligomers, polymers, and inverted micelles could be observed upon variation of the solvent polarity and the concentration. Moreover, this system is highly responsive toward molecular stimuli such as merocyanine molecules with the barbituric acid motif that are bound by the Hamilton receptors. Detailed UV/Vis absorption studies provided insight into isodesmic or cooperative steps during the self-assembly of 8 into different species. The size of the aggregates in solution and the morphology on substrates have been explored by a combination of dynamic light scattering (DLS), atomic force microscopy (AFM), and TEM investigations.}, author = {Schmidt, Ralf and Uemura, Shinobu and Würthner, Frank}, journal = {Chemistry – A European Journal}, keywords = {myown}, number = 46, pages = {13706–13715}, publisher = {WILEY-VCH Verlag}, title = {Solvent- and Guest-Responsive Self-Assembly of Hamilton Receptor Tethered Bis(merocyanine) Dyes}, volume = 16, year = 2010 }

  %0 Journal Article %1 CHEM:CHEM201002159 %A Schmidt, Ralf %A Uemura, Shinobu %A Würthner, Frank %D 2010 %I WILEY-VCH Verlag %J Chemistry – A European Journal %N 46 %P 13706--13715 %R 10.1002/chem.201002159 %T Solvent- and Guest-Responsive Self-Assembly of Hamilton Receptor Tethered Bis(merocyanine) Dyes %U http://dx.doi.org/10.1002/chem.201002159 %V 16 %X A novel supramolecular building block (8) that consists of a Hamilton receptor and two merocyanine dyes has been synthesized, and the self-assembly based on orthogonal hydrogen bonding and dipolar interactions has been studied in detail. Different self-assembled species, including oligomers, polymers, and inverted micelles could be observed upon variation of the solvent polarity and the concentration. Moreover, this system is highly responsive toward molecular stimuli such as merocyanine molecules with the barbituric acid motif that are bound by the Hamilton receptors. Detailed UV/Vis absorption studies provided insight into isodesmic or cooperative steps during the self-assembly of 8 into different species. The size of the aggregates in solution and the morphology on substrates have been explored by a combination of dynamic light scattering (DLS), atomic force microscopy (AFM), and TEM investigations.
• Direct Comparison of Highly Efficient Solution- and Vacuum-Processed Organic Solar Cells Based on Merocyanine Dyes. Kronenberg, Nils M.; Steinmann, Vera; Bürckstümmer, Hannah; Hwang, Jaehyung; Hertel, Dirk; Würthner, Frank; Meerholz, Klaus. In Advanced Materials, 22(37), pp. 4193–4197. 2010.
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  @article{ADMA:ADMA201000800, author = {Kronenberg, Nils M. and Steinmann, Vera and Bürckstümmer, Hannah and Hwang, Jaehyung and Hertel, Dirk and Würthner, Frank and Meerholz, Klaus}, journal = {Advanced Materials}, keywords = {myown}, number = 37, pages = {4193–4197}, publisher = {WILEY-VCH Verlag}, title = {Direct Comparison of Highly Efficient Solution- and Vacuum-Processed Organic Solar Cells Based on Merocyanine Dyes}, volume = 22, year = 2010 }

  %0 Journal Article %1 ADMA:ADMA201000800 %A Kronenberg, Nils M. %A Steinmann, Vera %A Bürckstümmer, Hannah %A Hwang, Jaehyung %A Hertel, Dirk %A Würthner, Frank %A Meerholz, Klaus %D 2010 %I WILEY-VCH Verlag %J Advanced Materials %N 37 %P 4193--4197 %R 10.1002/adma.201000800 %T Direct Comparison of Highly Efficient Solution- and Vacuum-Processed Organic Solar Cells Based on Merocyanine Dyes %U http://dx.doi.org/10.1002/adma.201000800 %V 22
• Chiral Self-Recognition and Self-Discrimination of Strapped Perylene Bisimides by π-Stacking Dimerization. Safont-Sempere, Marina M.; Osswald, Peter; Radacki, Krzysztof; Würthner, Frank. In Chemistry – A European Journal, 16(25), pp. 7380–7384. 2010.
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  @article{CHEM:CHEM201001137, author = {Safont-Sempere, Marina M. and Osswald, Peter and Radacki, Krzysztof and Würthner, Frank}, journal = {Chemistry – A European Journal}, keywords = {myown}, number = 25, pages = {7380–7384}, publisher = {WILEY-VCH Verlag}, title = {Chiral Self-Recognition and Self-Discrimination of Strapped Perylene Bisimides by π-Stacking Dimerization}, volume = 16, year = 2010 }

  %0 Journal Article %1 CHEM:CHEM201001137 %A Safont-Sempere, Marina M. %A Osswald, Peter %A Radacki, Krzysztof %A Würthner, Frank %D 2010 %I WILEY-VCH Verlag %J Chemistry – A European Journal %N 25 %P 7380--7384 %R 10.1002/chem.201001137 %T Chiral Self-Recognition and Self-Discrimination of Strapped Perylene Bisimides by π-Stacking Dimerization %U http://dx.doi.org/10.1002/chem.201001137 %V 16
• Highly fluorescent water-soluble polyglycerol-dendronized perylene bisimide dyes. Heek, Timm; Fasting, Carlo; Rest, Christina; Zhang, Xin; Würthner, Frank; Haag, Rainer. In Chem. Commun., 46(11), pp. 1884–1886. 2010.
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  Water-soluble perylene tetracarboxylic acid bisimides (PBIs) with terminally linked polyglycerol dendrons of four different generations have been synthesized. These PBI dyes reveal a strong dendritic effect, enabling outstanding fluorescence quantum yields in water up to almost 100% for the highest dendron generation.

  @article{B923806A, abstract = {Water-soluble perylene tetracarboxylic acid bisimides (PBIs) with terminally linked polyglycerol dendrons of four different generations have been synthesized. These PBI dyes reveal a strong dendritic effect{,} enabling outstanding fluorescence quantum yields in water up to almost 100% for the highest dendron generation.}, author = {Heek, Timm and Fasting, Carlo and Rest, Christina and Zhang, Xin and Würthner, Frank and Haag, Rainer}, journal = {Chem. Commun.}, keywords = {myown}, number = 11, pages = {1884-1886}, publisher = {The Royal Society of Chemistry}, title = {Highly fluorescent water-soluble polyglycerol-dendronized perylene bisimide dyes}, volume = 46, year = 2010 }

  %0 Journal Article %1 B923806A %A Heek, Timm %A Fasting, Carlo %A Rest, Christina %A Zhang, Xin %A Würthner, Frank %A Haag, Rainer %D 2010 %I The Royal Society of Chemistry %J Chem. Commun. %N 11 %P 1884-1886 %R 10.1039/B923806A %T Highly fluorescent water-soluble polyglycerol-dendronized perylene bisimide dyes %U http://dx.doi.org/10.1039/B923806A %V 46 %X Water-soluble perylene tetracarboxylic acid bisimides (PBIs) with terminally linked polyglycerol dendrons of four different generations have been synthesized. These PBI dyes reveal a strong dendritic effect, enabling outstanding fluorescence quantum yields in water up to almost 100% for the highest dendron generation.
• Broadband femtosecond circular dichroism spectrometer with white-light polarization control. Trifonov, Anton; Buchvarov, Ivan; Lohr, Andreas; Würthner, Frank; Fiebig, Torsten. In Review of Scientific Instruments, 81(4), p. 043104. 2010.
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  @article{doi:10.1063/1.3340892, author = {Trifonov, Anton and Buchvarov, Ivan and Lohr, Andreas and Würthner, Frank and Fiebig, Torsten}, journal = {Review of Scientific Instruments}, keywords = {myown}, number = 4, pages = {043104}, title = {Broadband femtosecond circular dichroism spectrometer with white-light polarization control}, volume = 81, year = 2010 }

  %0 Journal Article %1 doi:10.1063/1.3340892 %A Trifonov, Anton %A Buchvarov, Ivan %A Lohr, Andreas %A Würthner, Frank %A Fiebig, Torsten %D 2010 %J Review of Scientific Instruments %N 4 %P 043104 %R 10.1063/1.3340892 %T Broadband femtosecond circular dichroism spectrometer with white-light polarization control %U https://doi.org/10.1063/1.3340892 %V 81
• Interlayer energy transfer between perylene diimide and phthalocyanine monolayers. Lehtivuori, Heli; Kumpulainen, Tatu; Efimov, Alexander; Lemmetyinen, Helge; Würthner, Frank; Tkachenko, Nikolai V. In Journal of Photochemistry and Photobiology A: Chemistry, 211(1), pp. 26–31. 2010.
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  Abstract Interlayer energy transfer from perylene diimide (PDI12) layers to phthalocyanine layers was studied using steady-state absorption, fluorescence, and time-resolved fluorescence and microscopy methods. The layers were prepared by Langmuir–Schäfer method, spaced by a few layers of octadecylamine deposited by Langmuir–Blodgett method, when required. The fluorescence lifetime microscopy method allowed to exclude defects from the energy transfer analysis and calculate the fluorescence lifetimes of PDI12 for the defect free areas. The estimated distance dependence of the interlayer energy transfer follows roughly second order dependences on the distance with the critical distance of 6.9nm.

  @article{LEHTIVUORI201026, abstract = {Abstract Interlayer energy transfer from perylene diimide (PDI12) layers to phthalocyanine layers was studied using steady-state absorption, fluorescence, and time-resolved fluorescence and microscopy methods. The layers were prepared by Langmuir–Schäfer method, spaced by a few layers of octadecylamine deposited by Langmuir–Blodgett method, when required. The fluorescence lifetime microscopy method allowed to exclude defects from the energy transfer analysis and calculate the fluorescence lifetimes of PDI12 for the defect free areas. The estimated distance dependence of the interlayer energy transfer follows roughly second order dependences on the distance with the critical distance of 6.9nm.}, author = {Lehtivuori, Heli and Kumpulainen, Tatu and Efimov, Alexander and Lemmetyinen, Helge and Würthner, Frank and Tkachenko, Nikolai V.}, journal = {Journal of Photochemistry and Photobiology A: Chemistry}, keywords = {microscopy}, number = 1, pages = {26 - 31}, title = {Interlayer energy transfer between perylene diimide and phthalocyanine monolayers}, volume = 211, year = 2010 }

  %0 Journal Article %1 LEHTIVUORI201026 %A Lehtivuori, Heli %A Kumpulainen, Tatu %A Efimov, Alexander %A Lemmetyinen, Helge %A Würthner, Frank %A Tkachenko, Nikolai V. %D 2010 %J Journal of Photochemistry and Photobiology A: Chemistry %N 1 %P 26 - 31 %R https://doi.org/10.1016/j.jphotochem.2010.01.017 %T Interlayer energy transfer between perylene diimide and phthalocyanine monolayers %U http://www.sciencedirect.com/science/article/pii/S1010603010000316 %V 211 %X Abstract Interlayer energy transfer from perylene diimide (PDI12) layers to phthalocyanine layers was studied using steady-state absorption, fluorescence, and time-resolved fluorescence and microscopy methods. The layers were prepared by Langmuir–Schäfer method, spaced by a few layers of octadecylamine deposited by Langmuir–Blodgett method, when required. The fluorescence lifetime microscopy method allowed to exclude defects from the energy transfer analysis and calculate the fluorescence lifetimes of PDI12 for the defect free areas. The estimated distance dependence of the interlayer energy transfer follows roughly second order dependences on the distance with the critical distance of 6.9nm.
• Perylene Bisimides with Rigid 2,2′-Biphenol Bridges at Bay Area as Conjugated Chiral Platforms. Xie, Zengqi; Würthner, Frank. In Organic Letters, 12(14), pp. 3204–3207. 2010.
  • [ Abstract ]
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  Facile nucleophilic substitution of two chlorine atoms by 2,2′-biphenol at one of the two bay areas (1,12- and 6,7-positions) of core-tetrachlorinated perylene bisimide afforded a novel, completely desymmetrized perylene bisimide building block, which could be further functionalized by substitution of the remaining two chlorine atoms. The atropisomers (P- and M-enantiomers) of the core twisted perylene bisimides were resolved by HPLC on a chiral column at room temperature, and the activation parameters for racemization were elucidated.

  @article{doi:10.1021/ol1011482, abstract = {Facile nucleophilic substitution of two chlorine atoms by 2,2′-biphenol at one of the two bay areas (1,12- and 6,7-positions) of core-tetrachlorinated perylene bisimide afforded a novel, completely desymmetrized perylene bisimide building block, which could be further functionalized by substitution of the remaining two chlorine atoms. The atropisomers (P- and M-enantiomers) of the core twisted perylene bisimides were resolved by HPLC on a chiral column at room temperature, and the activation parameters for racemization were elucidated.}, author = {Xie, Zengqi and Würthner, Frank}, journal = {Organic Letters}, keywords = {myown}, number = 14, pages = {3204-3207}, title = {Perylene Bisimides with Rigid 2,2′-Biphenol Bridges at Bay Area as Conjugated Chiral Platforms}, volume = 12, year = 2010 }

  %0 Journal Article %1 doi:10.1021/ol1011482 %A Xie, Zengqi %A Würthner, Frank %D 2010 %J Organic Letters %N 14 %P 3204-3207 %R 10.1021/ol1011482 %T Perylene Bisimides with Rigid 2,2′-Biphenol Bridges at Bay Area as Conjugated Chiral Platforms %U http://dx.doi.org/10.1021/ol1011482 %V 12 %X Facile nucleophilic substitution of two chlorine atoms by 2,2′-biphenol at one of the two bay areas (1,12- and 6,7-positions) of core-tetrachlorinated perylene bisimide afforded a novel, completely desymmetrized perylene bisimide building block, which could be further functionalized by substitution of the remaining two chlorine atoms. The atropisomers (P- and M-enantiomers) of the core twisted perylene bisimides were resolved by HPLC on a chiral column at room temperature, and the activation parameters for racemization were elucidated.
• High-Performance Air-Stable n-Type Organic Transistors Based on Core-Chlorinated Naphthalene Tetracarboxylic Diimides. Oh, Joon Hak; Suraru, Sabin–Lucian; Lee, Wen-Ya; Könemann, Martin; Höffken, Hans Wolfgang; Röger, Cornelia; Schmidt, Rüdiger; Chung, Yoonyoung; Chen, Wen-Chang; Würthner, Frank; Bao, Zhenan. In Advanced Functional Materials, 20(13), pp. 2148–2156. 2010.
  • [ Abstract ]
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  Core-chlorinated naphthalene tetracarboxylic diimides (NDIs) with fluoroalkyl chains are synthesized and employed for n-channel organic thin-film transistors (OTFTs). Structural analyses of the single crystals and thin films are performed and their charge-transport behavior is investigated in terms of structure–property relationships. NDIs with two chlorine substituents are shown to exhibit a herringbone structure with a very close π-plane distance (3.3–3.4 Å), a large π-stack overlap (slipping angle ca. 62°), and high crystal densities (2.046–2.091 g cm−3). These features result in excellent field-effect mobilities of up to 1.43 cm2 V−1 s−1 with minimal hysteresis and high on–off ratios (ca. 107) in air. This is similar to the highest n-channel mobilities in air reported so far. Despite the repulsive interactions of bulky Cl substituents, tetrachlorinated NDIs adopt a slip-stacked face-to-face packing with an interplanar distance of around 3.4 Å, resulting in a high mobility (up to 0.44 cm2 V−1 s−1). The air-stability of dichlorinated NDIs is superior to that of tetrachlorinated NDIs, despite of their higher LUMO levels. This is closely related to the denser packing of the fluorocarbon chains of dichlorinated NDIs, which serves as a kinetic barrier to the diffusion of ambient oxidants. Interestingly, these NDIs show an optimal performance either on bare SiO2 or on octadecyltrimethoxysilane (OTS)-treated SiO2, depending on the carbon number of the fluoroalkyl chains. Their synthetic simplicity and processing versatility combined with their high performance make these semiconductors highly promising for practical applications in flexible electronics.

  @article{ADFM:ADFM201000425, abstract = {Core-chlorinated naphthalene tetracarboxylic diimides (NDIs) with fluoroalkyl chains are synthesized and employed for n-channel organic thin-film transistors (OTFTs). Structural analyses of the single crystals and thin films are performed and their charge-transport behavior is investigated in terms of structure–property relationships. NDIs with two chlorine substituents are shown to exhibit a herringbone structure with a very close π-plane distance (3.3–3.4 Å), a large π-stack overlap (slipping angle ca. 62°), and high crystal densities (2.046–2.091 g cm−3). These features result in excellent field-effect mobilities of up to 1.43 cm2 V−1 s−1 with minimal hysteresis and high on–off ratios (ca. 107) in air. This is similar to the highest n-channel mobilities in air reported so far. Despite the repulsive interactions of bulky Cl substituents, tetrachlorinated NDIs adopt a slip-stacked face-to-face packing with an interplanar distance of around 3.4 Å, resulting in a high mobility (up to 0.44 cm2 V−1 s−1). The air-stability of dichlorinated NDIs is superior to that of tetrachlorinated NDIs, despite of their higher LUMO levels. This is closely related to the denser packing of the fluorocarbon chains of dichlorinated NDIs, which serves as a kinetic barrier to the diffusion of ambient oxidants. Interestingly, these NDIs show an optimal performance either on bare SiO2 or on octadecyltrimethoxysilane (OTS)-treated SiO2, depending on the carbon number of the fluoroalkyl chains. Their synthetic simplicity and processing versatility combined with their high performance make these semiconductors highly promising for practical applications in flexible electronics.}, author = {Oh, Joon Hak and Suraru, Sabin–Lucian and Lee, Wen-Ya and Könemann, Martin and Höffken, Hans Wolfgang and Röger, Cornelia and Schmidt, Rüdiger and Chung, Yoonyoung and Chen, Wen-Chang and Würthner, Frank and Bao, Zhenan}, journal = {Advanced Functional Materials}, keywords = {myown}, number = 13, pages = {2148–2156}, publisher = {WILEY-VCH Verlag}, title = {High-Performance Air-Stable n-Type Organic Transistors Based on Core-Chlorinated Naphthalene Tetracarboxylic Diimides}, volume = 20, year = 2010 }

  %0 Journal Article %1 ADFM:ADFM201000425 %A Oh, Joon Hak %A Suraru, Sabin–Lucian %A Lee, Wen-Ya %A Könemann, Martin %A Höffken, Hans Wolfgang %A Röger, Cornelia %A Schmidt, Rüdiger %A Chung, Yoonyoung %A Chen, Wen-Chang %A Würthner, Frank %A Bao, Zhenan %D 2010 %I WILEY-VCH Verlag %J Advanced Functional Materials %N 13 %P 2148--2156 %R 10.1002/adfm.201000425 %T High-Performance Air-Stable n-Type Organic Transistors Based on Core-Chlorinated Naphthalene Tetracarboxylic Diimides %U http://dx.doi.org/10.1002/adfm.201000425 %V 20 %X Core-chlorinated naphthalene tetracarboxylic diimides (NDIs) with fluoroalkyl chains are synthesized and employed for n-channel organic thin-film transistors (OTFTs). Structural analyses of the single crystals and thin films are performed and their charge-transport behavior is investigated in terms of structure–property relationships. NDIs with two chlorine substituents are shown to exhibit a herringbone structure with a very close π-plane distance (3.3–3.4 Å), a large π-stack overlap (slipping angle ca. 62°), and high crystal densities (2.046–2.091 g cm−3). These features result in excellent field-effect mobilities of up to 1.43 cm2 V−1 s−1 with minimal hysteresis and high on–off ratios (ca. 107) in air. This is similar to the highest n-channel mobilities in air reported so far. Despite the repulsive interactions of bulky Cl substituents, tetrachlorinated NDIs adopt a slip-stacked face-to-face packing with an interplanar distance of around 3.4 Å, resulting in a high mobility (up to 0.44 cm2 V−1 s−1). The air-stability of dichlorinated NDIs is superior to that of tetrachlorinated NDIs, despite of their higher LUMO levels. This is closely related to the denser packing of the fluorocarbon chains of dichlorinated NDIs, which serves as a kinetic barrier to the diffusion of ambient oxidants. Interestingly, these NDIs show an optimal performance either on bare SiO2 or on octadecyltrimethoxysilane (OTS)-treated SiO2, depending on the carbon number of the fluoroalkyl chains. Their synthetic simplicity and processing versatility combined with their high performance make these semiconductors highly promising for practical applications in flexible electronics.
• Photoinduced Processes in Self-Assembled Porphyrin/Perylene Bisimide Metallosupramolecular Boxes. Indelli, M. Teresa; Chiorboli, Claudio; Scandola, Franco; Iengo, Elisabetta; Osswald, Peter; Würthner, Frank. In The Journal of Physical Chemistry B, 114(45), pp. 14495–14504. 2010.

  PMID: 20524702
  • [ Abstract ]
  • [ BibTeX ]
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  • [ DOI ]
  Two new supramolecular boxes, (ZnMC)2(rPBI)2 and (ZnMC)2(gPBI)2, have been obtained by axial coordination of N,N′-dipyridyl-functionalized perylene bisimide (PBI) dyes to the zinc ion centers of two 2+2 porphyrin metallacycles (ZnMC = [trans,cis,cis-RuCl2(CO)2(Zn·4′-cis-DPyP)]2). The two molecular boxes involve PBI pillars with different substituents at the bay area: the “red” PBI (rPBI = N,N′-di(4-pyridyl)-1,6,7,12-tetra(4-tert-butylphenoxy)perylene-3,4:9,10-tetracarboxylic acid bisimide) containing tert-butylphenoxy substituents and the “green” PBI (gPBI = N,N′-di(4-pyridyl)-1,7-bis(pyrrolidin-1-yl)perylene-3,4:9,10-tetracarboxylic acid bisimide) bearing pyrrolidinyl substituents. Due to the rigidity of the modules and the simultaneous formation of four pyridine−zinc bonds, these discrete adducts self-assemble quantitatively and are remarkably stable in dichloromethane solution. The photophysical behavior of the new supramolecular boxes has been studied in dichloromethane by emission spectroscopy and ultrafast absorption techniques. A different photophysical behavior is observed for the two systems. In (ZnMC)2(rPBI)2, efficient electron transfer quenching of both perylene bisimide and zinc porphyrin chromophores is observed, leading to a charge separated state, PBI−−Zn+, in which a perylene bisimide unit is reduced and zinc porphyrin is oxidized. In the deactivation of the perylene bisimide localized excited state, an intermediate zwitterionic charge transfer state of type PBI−−PBI+ seems to play a relevant role. In (ZnMC)2(gPBI)2, singlet energy transfer from the Zn porphyrin chromophores to the perylene bisimide units occurs with an efficiency of 0.7. This lower than unity value is due to a competing electron transfer quenching, leading to the charge separated state PBI−−Zn+. The distinct photophysical behavior of these two supramolecular boxes is interpreted in terms of energy changes occurring upon replacement of the “red” rPBI by “green” gPBI.

  @article{doi:10.1021/jp101849m, abstract = {Two new supramolecular boxes, (ZnMC)2(rPBI)2 and (ZnMC)2(gPBI)2, have been obtained by axial coordination of N,N′-dipyridyl-functionalized perylene bisimide (PBI) dyes to the zinc ion centers of two 2+2 porphyrin metallacycles (ZnMC = [trans,cis,cis-RuCl2(CO)2(Zn·4′-cis-DPyP)]2). The two molecular boxes involve PBI pillars with different substituents at the bay area: the “red” PBI (rPBI = N,N′-di(4-pyridyl)-1,6,7,12-tetra(4-tert-butylphenoxy)perylene-3,4:9,10-tetracarboxylic acid bisimide) containing tert-butylphenoxy substituents and the “green” PBI (gPBI = N,N′-di(4-pyridyl)-1,7-bis(pyrrolidin-1-yl)perylene-3,4:9,10-tetracarboxylic acid bisimide) bearing pyrrolidinyl substituents. Due to the rigidity of the modules and the simultaneous formation of four pyridine−zinc bonds, these discrete adducts self-assemble quantitatively and are remarkably stable in dichloromethane solution. The photophysical behavior of the new supramolecular boxes has been studied in dichloromethane by emission spectroscopy and ultrafast absorption techniques. A different photophysical behavior is observed for the two systems. In (ZnMC)2(rPBI)2, efficient electron transfer quenching of both perylene bisimide and zinc porphyrin chromophores is observed, leading to a charge separated state, PBI−−Zn+, in which a perylene bisimide unit is reduced and zinc porphyrin is oxidized. In the deactivation of the perylene bisimide localized excited state, an intermediate zwitterionic charge transfer state of type PBI−−PBI+ seems to play a relevant role. In (ZnMC)2(gPBI)2, singlet energy transfer from the Zn porphyrin chromophores to the perylene bisimide units occurs with an efficiency of 0.7. This lower than unity value is due to a competing electron transfer quenching, leading to the charge separated state PBI−−Zn+. The distinct photophysical behavior of these two supramolecular boxes is interpreted in terms of energy changes occurring upon replacement of the “red” rPBI by “green” gPBI.}, author = {Indelli, M. Teresa and Chiorboli, Claudio and Scandola, Franco and Iengo, Elisabetta and Osswald, Peter and Würthner, Frank}, journal = {The Journal of Physical Chemistry B}, keywords = {myown}, note = {PMID: 20524702}, number = 45, pages = {14495-14504}, title = {Photoinduced Processes in Self-Assembled Porphyrin/Perylene Bisimide Metallosupramolecular Boxes}, volume = 114, year = 2010 }

  %0 Journal Article %1 doi:10.1021/jp101849m %A Indelli, M. Teresa %A Chiorboli, Claudio %A Scandola, Franco %A Iengo, Elisabetta %A Osswald, Peter %A Würthner, Frank %D 2010 %J The Journal of Physical Chemistry B %N 45 %P 14495-14504 %R 10.1021/jp101849m %T Photoinduced Processes in Self-Assembled Porphyrin/Perylene Bisimide Metallosupramolecular Boxes %U http://dx.doi.org/10.1021/jp101849m %V 114 %X Two new supramolecular boxes, (ZnMC)2(rPBI)2 and (ZnMC)2(gPBI)2, have been obtained by axial coordination of N,N′-dipyridyl-functionalized perylene bisimide (PBI) dyes to the zinc ion centers of two 2+2 porphyrin metallacycles (ZnMC = [trans,cis,cis-RuCl2(CO)2(Zn·4′-cis-DPyP)]2). The two molecular boxes involve PBI pillars with different substituents at the bay area: the “red” PBI (rPBI = N,N′-di(4-pyridyl)-1,6,7,12-tetra(4-tert-butylphenoxy)perylene-3,4:9,10-tetracarboxylic acid bisimide) containing tert-butylphenoxy substituents and the “green” PBI (gPBI = N,N′-di(4-pyridyl)-1,7-bis(pyrrolidin-1-yl)perylene-3,4:9,10-tetracarboxylic acid bisimide) bearing pyrrolidinyl substituents. Due to the rigidity of the modules and the simultaneous formation of four pyridine−zinc bonds, these discrete adducts self-assemble quantitatively and are remarkably stable in dichloromethane solution. The photophysical behavior of the new supramolecular boxes has been studied in dichloromethane by emission spectroscopy and ultrafast absorption techniques. A different photophysical behavior is observed for the two systems. In (ZnMC)2(rPBI)2, efficient electron transfer quenching of both perylene bisimide and zinc porphyrin chromophores is observed, leading to a charge separated state, PBI−−Zn+, in which a perylene bisimide unit is reduced and zinc porphyrin is oxidized. In the deactivation of the perylene bisimide localized excited state, an intermediate zwitterionic charge transfer state of type PBI−−PBI+ seems to play a relevant role. In (ZnMC)2(gPBI)2, singlet energy transfer from the Zn porphyrin chromophores to the perylene bisimide units occurs with an efficiency of 0.7. This lower than unity value is due to a competing electron transfer quenching, leading to the charge separated state PBI−−Zn+. The distinct photophysical behavior of these two supramolecular boxes is interpreted in terms of energy changes occurring upon replacement of the “red” rPBI by “green” gPBI.
• DABCO-Mediated Self-Assembly of Zinc Porphyrin–Perylene Bisimide Monodisperse Multichromophoric Nanoparticles. Osswald, Peter; You, Chang-Cheng; Stepanenko, Vladimir; Würthner, Frank. In Chemistry – A European Journal, 16(8), pp. 2386–2390. 2010.
  • [ BibTeX ]
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  • [ DOI ]
  @article{CHEM:CHEM200902944, author = {Osswald, Peter and You, Chang-Cheng and Stepanenko, Vladimir and Würthner, Frank}, journal = {Chemistry – A European Journal}, keywords = {myown}, number = 8, pages = {2386–2390}, publisher = {WILEY-VCH Verlag}, title = {DABCO-Mediated Self-Assembly of Zinc Porphyrin–Perylene Bisimide Monodisperse Multichromophoric Nanoparticles}, volume = 16, year = 2010 }

  %0 Journal Article %1 CHEM:CHEM200902944 %A Osswald, Peter %A You, Chang-Cheng %A Stepanenko, Vladimir %A Würthner, Frank %D 2010 %I WILEY-VCH Verlag %J Chemistry – A European Journal %N 8 %P 2386--2390 %R 10.1002/chem.200902944 %T DABCO-Mediated Self-Assembly of Zinc Porphyrin–Perylene Bisimide Monodisperse Multichromophoric Nanoparticles %U http://dx.doi.org/10.1002/chem.200902944 %V 16
• Tailored merocyanine dyes for solution-processed BHJ solar cells. Burckstummer, Hannah; Kronenberg, Nils Michael; Gsanger, Marcel; Stolte, Matthias; Meerholz, Klaus; Würthner, Frank. In J. Mater. Chem., 20(2), pp. 240–243. 2010.
  • [ Abstract ]
  • [ BibTeX ]
  • [ EndNote ]
  • [ DOI ]
  A solution-cast photovoltaic film of a newly designed merocyanine chromophore blended with PCBM exhibited an appreciably high power conversion efficiency of 2.59%.

  @article{B916181C, abstract = {A solution-cast photovoltaic film of a newly designed merocyanine chromophore blended with PCBM exhibited an appreciably high power conversion efficiency of 2.59%.}, author = {Burckstummer, Hannah and Kronenberg, Nils Michael and Gsanger, Marcel and Stolte, Matthias and Meerholz, Klaus and Würthner, Frank}, journal = {J. Mater. Chem.}, keywords = {myown}, number = 2, pages = {240-243}, publisher = {The Royal Society of Chemistry}, title = {Tailored merocyanine dyes for solution-processed BHJ solar cells}, volume = 20, year = 2010 }

  %0 Journal Article %1 B916181C %A Burckstummer, Hannah %A Kronenberg, Nils Michael %A Gsanger, Marcel %A Stolte, Matthias %A Meerholz, Klaus %A Würthner, Frank %D 2010 %I The Royal Society of Chemistry %J J. Mater. Chem. %N 2 %P 240-243 %R 10.1039/B916181C %T Tailored merocyanine dyes for solution-processed BHJ solar cells %U http://dx.doi.org/10.1039/B916181C %V 20 %X A solution-cast photovoltaic film of a newly designed merocyanine chromophore blended with PCBM exhibited an appreciably high power conversion efficiency of 2.59%.
• Langmuir−Schaeffer Films from a π−π Stacking Perylenediimide Dye: Organization and Charge Transfer Properties. Tolkki, Antti; Vuorimaa, Elina; Chukharev, Vladimir; Lemmetyinen, Helge; Ihalainen, Petri; Peltonen, Jouko; Dehm, Volker; Würthner, Frank. In Langmuir, 26(9), pp. 6630–6637. 2010.

  PMID: 20025208
  • [ Abstract ]
  • [ BibTeX ]
  • [ EndNote ]
  • [ DOI ]
  The organization of π−π stacking perylenediimide (PDI) derivative, PDI12, was studied in solution and in thin films. Films were prepared with the Langmuir−Schaeffer (LS) method and characterized by means of AFM, optical profilometry, steady-state absorption, emission, fluorescence lifetime, and transient photovoltage measurements. The columnar aggregates observed previously in PDI12 solutions and in spin-coated films persist also in LS films. Because of the specific conditions during the preparation of the LS film, i.e., hydrophobic interactions and lateral compression, the columnar aggregates seem to organize with their long axis perpendicular to the layer plane whereas in spin-coated films the columns were oriented parallel to the layer plane. According to AFM and profilometer results, the thickness of LS monolayer of PDI12 is 10 nm, indicating that it consists mainly of aggregates, each containing ∼30 monomers. Intermolecular photoinduced energy and electron transfer processes in C60|PDI12 double layer junction were studied. The fluorescence lifetime of PDI12 film is exceptionally long, but the quenching is very efficient in the presence of C60. In charge transfer studies, long-lived photovoltage signal was observed for the double layer. Results of this work indicate that PDI12 acts as an electron acceptor and fullerene C60 as an electron donor.

  @article{doi:10.1021/la903978y, abstract = {The organization of π−π stacking perylenediimide (PDI) derivative, PDI12, was studied in solution and in thin films. Films were prepared with the Langmuir−Schaeffer (LS) method and characterized by means of AFM, optical profilometry, steady-state absorption, emission, fluorescence lifetime, and transient photovoltage measurements. The columnar aggregates observed previously in PDI12 solutions and in spin-coated films persist also in LS films. Because of the specific conditions during the preparation of the LS film, i.e., hydrophobic interactions and lateral compression, the columnar aggregates seem to organize with their long axis perpendicular to the layer plane whereas in spin-coated films the columns were oriented parallel to the layer plane. According to AFM and profilometer results, the thickness of LS monolayer of PDI12 is 10 nm, indicating that it consists mainly of aggregates, each containing ∼30 monomers. Intermolecular photoinduced energy and electron transfer processes in C60|PDI12 double layer junction were studied. The fluorescence lifetime of PDI12 film is exceptionally long, but the quenching is very efficient in the presence of C60. In charge transfer studies, long-lived photovoltage signal was observed for the double layer. Results of this work indicate that PDI12 acts as an electron acceptor and fullerene C60 as an electron donor.}, author = {Tolkki, Antti and Vuorimaa, Elina and Chukharev, Vladimir and Lemmetyinen, Helge and Ihalainen, Petri and Peltonen, Jouko and Dehm, Volker and Würthner, Frank}, journal = {Langmuir}, keywords = {myown}, note = {PMID: 20025208}, number = 9, pages = {6630-6637}, title = {Langmuir−Schaeffer Films from a π−π Stacking Perylenediimide Dye: Organization and Charge Transfer Properties}, volume = 26, year = 2010 }

  %0 Journal Article %1 doi:10.1021/la903978y %A Tolkki, Antti %A Vuorimaa, Elina %A Chukharev, Vladimir %A Lemmetyinen, Helge %A Ihalainen, Petri %A Peltonen, Jouko %A Dehm, Volker %A Würthner, Frank %D 2010 %J Langmuir %N 9 %P 6630-6637 %R 10.1021/la903978y %T Langmuir−Schaeffer Films from a π−π Stacking Perylenediimide Dye: Organization and Charge Transfer Properties %U http://dx.doi.org/10.1021/la903978y %V 26 %X The organization of π−π stacking perylenediimide (PDI) derivative, PDI12, was studied in solution and in thin films. Films were prepared with the Langmuir−Schaeffer (LS) method and characterized by means of AFM, optical profilometry, steady-state absorption, emission, fluorescence lifetime, and transient photovoltage measurements. The columnar aggregates observed previously in PDI12 solutions and in spin-coated films persist also in LS films. Because of the specific conditions during the preparation of the LS film, i.e., hydrophobic interactions and lateral compression, the columnar aggregates seem to organize with their long axis perpendicular to the layer plane whereas in spin-coated films the columns were oriented parallel to the layer plane. According to AFM and profilometer results, the thickness of LS monolayer of PDI12 is 10 nm, indicating that it consists mainly of aggregates, each containing ∼30 monomers. Intermolecular photoinduced energy and electron transfer processes in C60|PDI12 double layer junction were studied. The fluorescence lifetime of PDI12 film is exceptionally long, but the quenching is very efficient in the presence of C60. In charge transfer studies, long-lived photovoltage signal was observed for the double layer. Results of this work indicate that PDI12 acts as an electron acceptor and fullerene C60 as an electron donor.
• FRET and ligand related NON-FRET processes in single quantum dot-perylene bisimide assemblies. Kowerko, Danny; Schuster, Jorg; Amecke, Nicole; Abdel-Mottaleb, Mohammed; Dobrawa, Rainer; Würthner, Frank; von Borczyskowski, Christian. In Phys. Chem. Chem. Phys., 12(16), pp. 4112–4123. 2010.
  • [ Abstract ]
  • [ BibTeX ]
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  • [ DOI ]
  Nanoassemblies are formed via self-assembly of ZnS capped CdSe quantum dots (QD) and perylene bisimide dyes (PBI). Upon assembly formation with functionalized dye molecules the QD photoluminescence (PL) is quenched. Quenching has been assigned partly to FRET (fluorescence resonance energy transfer) and NON-FRET processes. By means of time resolved single particle spectroscopy of immobilized QD-dye assemblies, it is demonstrated that NON-FRET processes are due to new non-radiative decay channels caused by the assembly formation process itself. Immobilized (single) assemblies exhibit the same processes as ensembles of assemblies in toluene solution. Only one dye molecule on a QD quenches the PL up to 50%, which is much stronger than is expected when replacing a volume related number of ligands. NON-FRET processes are distinct from photoinduced charge and/or energy transfer. A combination of a Stern-Volmer and FRET analysis of ensemble experiments supports the investigation of the dynamics of assembly formation at extremely low concentration ratios of PBI to QD. This allows us to distinguish between the effects of PBI and ligands on PL quenching on a single molecule level which is not possible in conventional ligand dynamic experiments.

  @article{B910308B, abstract = {Nanoassemblies are formed via self-assembly of ZnS capped CdSe quantum dots (QD) and perylene bisimide dyes (PBI). Upon assembly formation with functionalized dye molecules the QD photoluminescence (PL) is quenched. Quenching has been assigned partly to FRET (fluorescence resonance energy transfer) and NON-FRET processes. By means of time resolved single particle spectroscopy of immobilized QD-dye assemblies{,} it is demonstrated that NON-FRET processes are due to new non-radiative decay channels caused by the assembly formation process itself. Immobilized (single) assemblies exhibit the same processes as ensembles of assemblies in toluene solution. Only one dye molecule on a QD quenches the PL up to 50%{,} which is much stronger than is expected when replacing a volume related number of ligands. NON-FRET processes are distinct from photoinduced charge and/or energy transfer. A combination of a Stern-Volmer and FRET analysis of ensemble experiments supports the investigation of the dynamics of assembly formation at extremely low concentration ratios of PBI to QD. This allows us to distinguish between the effects of PBI and ligands on PL quenching on a single molecule level which is not possible in conventional ligand dynamic experiments.}, author = {Kowerko, Danny and Schuster, Jorg and Amecke, Nicole and Abdel-Mottaleb, Mohammed and Dobrawa, Rainer and Würthner, Frank and von Borczyskowski, Christian}, journal = {Phys. Chem. Chem. Phys.}, keywords = {myown}, number = 16, pages = {4112-4123}, publisher = {The Royal Society of Chemistry}, title = {FRET and ligand related NON-FRET processes in single quantum dot-perylene bisimide assemblies}, volume = 12, year = 2010 }

  %0 Journal Article %1 B910308B %A Kowerko, Danny %A Schuster, Jorg %A Amecke, Nicole %A Abdel-Mottaleb, Mohammed %A Dobrawa, Rainer %A Würthner, Frank %A von Borczyskowski, Christian %D 2010 %I The Royal Society of Chemistry %J Phys. Chem. Chem. Phys. %N 16 %P 4112-4123 %R 10.1039/B910308B %T FRET and ligand related NON-FRET processes in single quantum dot-perylene bisimide assemblies %U http://dx.doi.org/10.1039/B910308B %V 12 %X Nanoassemblies are formed via self-assembly of ZnS capped CdSe quantum dots (QD) and perylene bisimide dyes (PBI). Upon assembly formation with functionalized dye molecules the QD photoluminescence (PL) is quenched. Quenching has been assigned partly to FRET (fluorescence resonance energy transfer) and NON-FRET processes. By means of time resolved single particle spectroscopy of immobilized QD-dye assemblies, it is demonstrated that NON-FRET processes are due to new non-radiative decay channels caused by the assembly formation process itself. Immobilized (single) assemblies exhibit the same processes as ensembles of assemblies in toluene solution. Only one dye molecule on a QD quenches the PL up to 50%, which is much stronger than is expected when replacing a volume related number of ligands. NON-FRET processes are distinct from photoinduced charge and/or energy transfer. A combination of a Stern-Volmer and FRET analysis of ensemble experiments supports the investigation of the dynamics of assembly formation at extremely low concentration ratios of PBI to QD. This allows us to distinguish between the effects of PBI and ligands on PL quenching on a single molecule level which is not possible in conventional ligand dynamic experiments.
• Ultrafast Bidirectional Photoswitching of a Spiropyran. Buback, Johannes; Kullmann, Martin; Langhojer, Florian; Nuernberger, Patrick; Schmidt, Ralf; Würthner, Frank; Brixner, Tobias. In J. Am. Chem. Soc., 132(46), pp. 16510–16519. 2010.

  PMID: 21047082
  • [ Abstract ]
  • [ BibTeX ]
  • [ EndNote ]
  • [ DOI ]
  We report on bidirectional photochemical switching of 6,8-dinitro-1′,3′,3′-trimethylspiro[2H-1-benzopyran-2,2′-indoline] (6,8-dinitro-BIPS) between the ring-closed spiropyran and the ring-open merocyanine form. This is studied by femtosecond three-color pump−repump−probe experiments. Both ring opening and ring closure are photoinduced. Completion of an entire cycle, consisting of opening and subsequent closure, can be achieved within 40 ps. A much shorter time (<6 ps) is needed for the converse cycle, consisting of initial ring closure and subsequent ring opening. Furthermore, we perform pump−probe experiments with ultraviolet/visible pump and visible/mid-infrared probe pulses for an unambiguous spectroscopic identification of the open and closed molecular forms. Following visible excitation of the ring-open molecules, ultrafast ring closure is observed directly in the mid-infrared. The quantum efficiencies for ring opening and ring closure starting from the respective equilibirum states are determined to be approximately 9\% and 40\%. These results show that 6,8-dinitro-BIPS is an ultrafast bidirectional molecular switch exhibiting a high quantum efficiency.

  @article{doi:10.1021/ja1062746, abstract = {We report on bidirectional photochemical switching of 6,8-dinitro-1′,3′,3′-trimethylspiro[2H-1-benzopyran-2,2′-indoline] (6,8-dinitro-BIPS) between the ring-closed spiropyran and the ring-open merocyanine form. This is studied by femtosecond three-color pump−repump−probe experiments. Both ring opening and ring closure are photoinduced. Completion of an entire cycle, consisting of opening and subsequent closure, can be achieved within 40 ps. A much shorter time (<6 ps) is needed for the converse cycle, consisting of initial ring closure and subsequent ring opening. Furthermore, we perform pump−probe experiments with ultraviolet/visible pump and visible/mid-infrared probe pulses for an unambiguous spectroscopic identification of the open and closed molecular forms. Following visible excitation of the ring-open molecules, ultrafast ring closure is observed directly in the mid-infrared. The quantum efficiencies for ring opening and ring closure starting from the respective equilibirum states are determined to be approximately 9\% and 40\%. These results show that 6,8-dinitro-BIPS is an ultrafast bidirectional molecular switch exhibiting a high quantum efficiency.}, author = {Buback, Johannes and Kullmann, Martin and Langhojer, Florian and Nuernberger, Patrick and Schmidt, Ralf and Würthner, Frank and Brixner, Tobias}, journal = {J. Am. Chem. Soc.}, keywords = {myown}, note = {PMID: 21047082}, number = 46, pages = {16510-16519}, title = {Ultrafast Bidirectional Photoswitching of a Spiropyran}, volume = 132, year = 2010 }

  %0 Journal Article %1 doi:10.1021/ja1062746 %A Buback, Johannes %A Kullmann, Martin %A Langhojer, Florian %A Nuernberger, Patrick %A Schmidt, Ralf %A Würthner, Frank %A Brixner, Tobias %D 2010 %J J. Am. Chem. Soc. %N 46 %P 16510-16519 %R 10.1021/ja1062746 %T Ultrafast Bidirectional Photoswitching of a Spiropyran %U http://dx.doi.org/10.1021/ja1062746 %V 132 %X We report on bidirectional photochemical switching of 6,8-dinitro-1′,3′,3′-trimethylspiro[2H-1-benzopyran-2,2′-indoline] (6,8-dinitro-BIPS) between the ring-closed spiropyran and the ring-open merocyanine form. This is studied by femtosecond three-color pump−repump−probe experiments. Both ring opening and ring closure are photoinduced. Completion of an entire cycle, consisting of opening and subsequent closure, can be achieved within 40 ps. A much shorter time (<6 ps) is needed for the converse cycle, consisting of initial ring closure and subsequent ring opening. Furthermore, we perform pump−probe experiments with ultraviolet/visible pump and visible/mid-infrared probe pulses for an unambiguous spectroscopic identification of the open and closed molecular forms. Following visible excitation of the ring-open molecules, ultrafast ring closure is observed directly in the mid-infrared. The quantum efficiencies for ring opening and ring closure starting from the respective equilibirum states are determined to be approximately 9\% and 40\%. These results show that 6,8-dinitro-BIPS is an ultrafast bidirectional molecular switch exhibiting a high quantum efficiency.
• Organic n-channel thin film transistors based on dichlorinated naphthalene diimides. Stolte, M.; Suraru, S.-L.; Würthner, Frank; Oh, J. H.; Bao, Z.; Brill, J.; Könemann, M.; Qu, J.; Zschieschang, U.; Klauck, H. In Proc.SPIE, 7778, pp. 7778 – 7778 . 2010.
  • [ Abstract ]
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  Five core-dichlorinated naphthalene diimides (NDIs) bearing several fluoroalkyl-substituents at the imide nitrogens were synthesized, characterized and employed in organic n-channel thin-film transistors with a vacuum-deposited semiconductor layer on 110 nm thick SiO₂ (100 nm)/AlO_x (8 nm)/SAM (1.7 nm) and 5.7 nm thick AlO_x (3.6 nm)/SAM (2.1 nm) gate dielectrics. The electron mobility of the thin-film transistors under ambient conditions is as large as 1.3 cm²/Vs on the thicker gate dielectric. On the thinner gate dielectric the mobility is lower (0.4 cm²/Vs) but enables switching at gate-source voltages of only 3V. Such outstanding performance together with the feasible synthetic access to these compounds make these semiconductors highly promising for low-cost, large-area, and flexible electronics.

  @article{stolte2010organic, abstract = {Five core-dichlorinated naphthalene diimides (NDIs) bearing several fluoroalkyl-substituents at the imide nitrogens were synthesized, characterized and employed in organic n-channel thin-film transistors with a vacuum-deposited semiconductor layer on 110 nm thick SiO₂ (100 nm)/AlO_x (8 nm)/SAM (1.7 nm) and 5.7 nm thick AlO_x (3.6 nm)/SAM (2.1 nm) gate dielectrics. The electron mobility of the thin-film transistors under ambient conditions is as large as 1.3 cm²/Vs on the thicker gate dielectric. On the thinner gate dielectric the mobility is lower (0.4 cm²/Vs) but enables switching at gate-source voltages of only 3V. Such outstanding performance together with the feasible synthetic access to these compounds make these semiconductors highly promising for low-cost, large-area, and flexible electronics.}, author = {Stolte, M. and Suraru, S.-L. and Würthner, Frank and Oh, J. H. and Bao, Z. and Brill, J. and Könemann, M. and Qu, J. and Zschieschang, U. and Klauck, H.}, journal = {Proc.SPIE}, keywords = {myown}, pages = {7778 - 7778 - 8}, title = {Organic n-channel thin film transistors based on dichlorinated naphthalene diimides}, volume = 7778, year = 2010 }

  %0 Journal Article %1 stolte2010organic %A Stolte, M. %A Suraru, S.-L. %A Würthner, Frank %A Oh, J. H. %A Bao, Z. %A Brill, J. %A Könemann, M. %A Qu, J. %A Zschieschang, U. %A Klauck, H. %D 2010 %J Proc.SPIE %P 7778 - 7778 - 8 %R 10.1117/12.859829 %T Organic n-channel thin film transistors based on dichlorinated naphthalene diimides %U http://dx.doi.org/10.1117/12.859829 %V 7778 %X Five core-dichlorinated naphthalene diimides (NDIs) bearing several fluoroalkyl-substituents at the imide nitrogens were synthesized, characterized and employed in organic n-channel thin-film transistors with a vacuum-deposited semiconductor layer on 110 nm thick SiO₂ (100 nm)/AlO_x (8 nm)/SAM (1.7 nm) and 5.7 nm thick AlO_x (3.6 nm)/SAM (2.1 nm) gate dielectrics. The electron mobility of the thin-film transistors under ambient conditions is as large as 1.3 cm²/Vs on the thicker gate dielectric. On the thinner gate dielectric the mobility is lower (0.4 cm²/Vs) but enables switching at gate-source voltages of only 3V. Such outstanding performance together with the feasible synthetic access to these compounds make these semiconductors highly promising for low-cost, large-area, and flexible electronics.
• Perylene bisimide macrocycles and their self-assembly on HOPG surfaces. Schlosser, Felix; Stepanenko, Vladimir; Würthner, Frank. In Chem. Commun., 46(44), pp. 8350–8352. 2010.
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  Acetylene-linked macrocycles incorporating multiple perylene tetracarboxylic acid bisimide (PBI) chromophores have been synthesised and separated by recycling GPC. The very first example of such macrocycles, i.e., cyclic trimer 5, containing three PBI dyes self-assembles into highly ordered donut-shaped unique hexagonal nanopatterns on HOPG surfaces as revealed by atomic force microscopy (AFM).

  @article{C0CC03004J, abstract = {Acetylene-linked macrocycles incorporating multiple perylene tetracarboxylic acid bisimide (PBI) chromophores have been synthesised and separated by recycling GPC. The very first example of such macrocycles{,} i.e.{,} cyclic trimer 5{,} containing three PBI dyes self-assembles into highly ordered donut-shaped unique hexagonal nanopatterns on HOPG surfaces as revealed by atomic force microscopy (AFM).}, author = {Schlosser, Felix and Stepanenko, Vladimir and Würthner, Frank}, journal = {Chem. Commun.}, keywords = {myown}, number = 44, pages = {8350-8352}, publisher = {The Royal Society of Chemistry}, title = {Perylene bisimide macrocycles and their self-assembly on HOPG surfaces}, volume = 46, year = 2010 }

  %0 Journal Article %1 C0CC03004J %A Schlosser, Felix %A Stepanenko, Vladimir %A Würthner, Frank %D 2010 %I The Royal Society of Chemistry %J Chem. Commun. %N 44 %P 8350-8352 %R 10.1039/C0CC03004J %T Perylene bisimide macrocycles and their self-assembly on HOPG surfaces %U http://dx.doi.org/10.1039/C0CC03004J %V 46 %X Acetylene-linked macrocycles incorporating multiple perylene tetracarboxylic acid bisimide (PBI) chromophores have been synthesised and separated by recycling GPC. The very first example of such macrocycles, i.e., cyclic trimer 5, containing three PBI dyes self-assembles into highly ordered donut-shaped unique hexagonal nanopatterns on HOPG surfaces as revealed by atomic force microscopy (AFM).
• Self-assembly and semiconductivity of an oligothiophene supergelator. Pratihar, Pampa; Ghosh, Suhrit; Stepanenko, Vladimir; Patwardhan, Sameer; Grozema, Ferdinand C.; Siebbeles, Laurens D. A.; Würthner, Frank. 2010.
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  @misc{pratihar2010selfassembly, author = {Pratihar, Pampa and Ghosh, Suhrit and Stepanenko, Vladimir and Patwardhan, Sameer and Grozema, Ferdinand C. and Siebbeles, Laurens D. A. and Würthner, Frank}, keywords = {myown}, publisher = {Beilstein-Institut}, title = {Self-assembly and semiconductivity of an oligothiophene supergelator}, type = {Full Research Paper}, year = 2010 }

  %0 Generic %1 pratihar2010selfassembly %A Pratihar, Pampa %A Ghosh, Suhrit %A Stepanenko, Vladimir %A Patwardhan, Sameer %A Grozema, Ferdinand C. %A Siebbeles, Laurens D. A. %A Würthner, Frank %D 2010 %I Beilstein-Institut %T Self-assembly and semiconductivity of an oligothiophene supergelator %U http://www.beilstein-journals.org/bjoc/articles/6/122
• Collective Fluorescence Blinking in Linear J-Aggregates Assisted by Long-Distance Exciton Migration. Lin, Hongzhen; Camacho, Rafael; Tian, Yuxi; Kaiser, Theo E.; Würthner, Frank; Scheblykin, Ivan G. In Nano Letters, 10(2), pp. 620–626. 2010.

  PMID: 20043661
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  Fluorescence blinking corresponding to collective quenching of up to 100 dye monomers is reported for individual J-aggregates of a perylene bisimide (PBI) dye. This implies an exciton diffusion length up to 70 nm in these one-dimensional assemblies. The number of quenched monomers was directly measured by comparing the fluorescence brightness of the J-aggregates with that of noncoupled PBI molecules. This brightness analysis technique is useful for unraveling photophysical parameters of any individual fluorescent nanosystem.

  @article{doi:10.1021/nl9036559, abstract = {Fluorescence blinking corresponding to collective quenching of up to 100 dye monomers is reported for individual J-aggregates of a perylene bisimide (PBI) dye. This implies an exciton diffusion length up to 70 nm in these one-dimensional assemblies. The number of quenched monomers was directly measured by comparing the fluorescence brightness of the J-aggregates with that of noncoupled PBI molecules. This brightness analysis technique is useful for unraveling photophysical parameters of any individual fluorescent nanosystem.}, author = {Lin, Hongzhen and Camacho, Rafael and Tian, Yuxi and Kaiser, Theo E. and Würthner, Frank and Scheblykin, Ivan G.}, journal = {Nano Letters}, keywords = {myown}, note = {PMID: 20043661}, number = 2, pages = {620-626}, title = {Collective Fluorescence Blinking in Linear J-Aggregates Assisted by Long-Distance Exciton Migration}, volume = 10, year = 2010 }

  %0 Journal Article %1 doi:10.1021/nl9036559 %A Lin, Hongzhen %A Camacho, Rafael %A Tian, Yuxi %A Kaiser, Theo E. %A Würthner, Frank %A Scheblykin, Ivan G. %D 2010 %J Nano Letters %N 2 %P 620-626 %R 10.1021/nl9036559 %T Collective Fluorescence Blinking in Linear J-Aggregates Assisted by Long-Distance Exciton Migration %U http://dx.doi.org/10.1021/nl9036559 %V 10 %X Fluorescence blinking corresponding to collective quenching of up to 100 dye monomers is reported for individual J-aggregates of a perylene bisimide (PBI) dye. This implies an exciton diffusion length up to 70 nm in these one-dimensional assemblies. The number of quenched monomers was directly measured by comparing the fluorescence brightness of the J-aggregates with that of noncoupled PBI molecules. This brightness analysis technique is useful for unraveling photophysical parameters of any individual fluorescent nanosystem.
• Spermine-Functionalized Perylene Bisimide Dyes—Highly Fluorescent Bola-Amphiphiles in Water. Rehm, Stefanie; Stepanenko, Vladimir; Zhang, Xin; Rehm, Thomas H.; Würthner, Frank. In Chemistry – A European Journal, 16(11), pp. 3372–3382. 2010.
  • [ Abstract ]
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  A series of four spermine-functionalized perylene bisimide dyes without linkers (1) and with linkers (2–4) between the chromophore and the polyamine was synthesized. Protonation of the spermine moieties resulted in the formation of highly water-soluble dyes with up to six positively charged ammonium ions. The aggregation behavior of these strongly fluorescent bola-amphiphiles was studied in pure water as solvent by UV/Vis and fluorescence spectroscopy, and an astonishingly high fluorescence quantum yield of up to Φfl=0.90 was observed for PBI 1. Atomic force microscopy and transmission electron microscopy were applied for the visualization of the aggregates on surfaces. Molecular modeling studies were performed by force-field calculations to explore the aggregate morphologies, which also provided valuable information on the influence of the additional alkylcarbonyl linkers. Our detailed spectroscopic and microscopic investigations revealed that the excellent optical properties of perylene bisimide chromophores can be used even in pure deionized water if their aggregation is efficiently suppressed.

  @article{CHEM:CHEM200902839, abstract = {A series of four spermine-functionalized perylene bisimide dyes without linkers (1) and with linkers (2–4) between the chromophore and the polyamine was synthesized. Protonation of the spermine moieties resulted in the formation of highly water-soluble dyes with up to six positively charged ammonium ions. The aggregation behavior of these strongly fluorescent bola-amphiphiles was studied in pure water as solvent by UV/Vis and fluorescence spectroscopy, and an astonishingly high fluorescence quantum yield of up to Φfl=0.90 was observed for PBI 1. Atomic force microscopy and transmission electron microscopy were applied for the visualization of the aggregates on surfaces. Molecular modeling studies were performed by force-field calculations to explore the aggregate morphologies, which also provided valuable information on the influence of the additional alkylcarbonyl linkers. Our detailed spectroscopic and microscopic investigations revealed that the excellent optical properties of perylene bisimide chromophores can be used even in pure deionized water if their aggregation is efficiently suppressed.}, author = {Rehm, Stefanie and Stepanenko, Vladimir and Zhang, Xin and Rehm, Thomas H. and Würthner, Frank}, journal = {Chemistry – A European Journal}, keywords = {myown}, number = 11, pages = {3372–3382}, publisher = {WILEY-VCH Verlag}, title = {Spermine-Functionalized Perylene Bisimide Dyes—Highly Fluorescent Bola-Amphiphiles in Water}, volume = 16, year = 2010 }

  %0 Journal Article %1 CHEM:CHEM200902839 %A Rehm, Stefanie %A Stepanenko, Vladimir %A Zhang, Xin %A Rehm, Thomas H. %A Würthner, Frank %D 2010 %I WILEY-VCH Verlag %J Chemistry – A European Journal %N 11 %P 3372--3382 %R 10.1002/chem.200902839 %T Spermine-Functionalized Perylene Bisimide Dyes—Highly Fluorescent Bola-Amphiphiles in Water %U http://dx.doi.org/10.1002/chem.200902839 %V 16 %X A series of four spermine-functionalized perylene bisimide dyes without linkers (1) and with linkers (2–4) between the chromophore and the polyamine was synthesized. Protonation of the spermine moieties resulted in the formation of highly water-soluble dyes with up to six positively charged ammonium ions. The aggregation behavior of these strongly fluorescent bola-amphiphiles was studied in pure water as solvent by UV/Vis and fluorescence spectroscopy, and an astonishingly high fluorescence quantum yield of up to Φfl=0.90 was observed for PBI 1. Atomic force microscopy and transmission electron microscopy were applied for the visualization of the aggregates on surfaces. Molecular modeling studies were performed by force-field calculations to explore the aggregate morphologies, which also provided valuable information on the influence of the additional alkylcarbonyl linkers. Our detailed spectroscopic and microscopic investigations revealed that the excellent optical properties of perylene bisimide chromophores can be used even in pure deionized water if their aggregation is efficiently suppressed.

• Self-Assembly of Bis(merocyanine) Tweezers into Discrete Bimolecular π-Stacks. Lohr, Andreas; Grüne, Matthias; Würthner, Frank. In Chemistry – A European Journal, 15(15), pp. 3691–3705. 2009.
  • [ Abstract ]
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  Dipolar aggregation: Examples of a novel class of tweezer molecules have been constructed through the tethering of two dipolar merocyanine chromophores. The electrostatic-interaction-directed self-assembly of these tweezers affords centrosymmetric bimolecular complexes with a unique aggregate geometry of four π-stacked chromophores (see picture) with an alternating arrangement of their dipole moments and very high dimerization constants, even in the good solvating solvent chloroform. Examples of a novel class of tweezer molecules have been constructed through the tethering of two dipolar merocyanine chromophores by a naphthalenedimethylene or dimethylenediphenylmethane spacer. The electrostatic-interaction-directed self-assembly of these bis(merocyanine) tweezers affords centrosymmetric bimolecular complexes with very high dimerization constants of up to >109 M−1, even in the good solvating solvent chloroform. This pronounced self-association of the bis(merocyanine) tweezers is attributed to the strongly dipolar nature of the merocyanine chromophores and a unique aggregate geometry of four π-stacked chromophores with an alternating arrangement of their dipole moments. The structural assignment of the tetrachromophoric π-stack has been accomplished by MALDI-TOF mass spectrometry and ROESY NMR spectroscopy. Furthermore, molecular modeling studies have accounted for the relationships between the dimerization constants and optical properties of the bimolecular complexes of the present bis(merocyanine) dyes and the structure of the spacer and the positions at which the merocyanine chromophores are attached.

  @article{CHEM:CHEM200802391, abstract = {Dipolar aggregation: Examples of a novel class of tweezer molecules have been constructed through the tethering of two dipolar merocyanine chromophores. The electrostatic-interaction-directed self-assembly of these tweezers affords centrosymmetric bimolecular complexes with a unique aggregate geometry of four π-stacked chromophores (see picture) with an alternating arrangement of their dipole moments and very high dimerization constants, even in the good solvating solvent chloroform. Examples of a novel class of tweezer molecules have been constructed through the tethering of two dipolar merocyanine chromophores by a naphthalenedimethylene or dimethylenediphenylmethane spacer. The electrostatic-interaction-directed self-assembly of these bis(merocyanine) tweezers affords centrosymmetric bimolecular complexes with very high dimerization constants of up to >109 M−1, even in the good solvating solvent chloroform. This pronounced self-association of the bis(merocyanine) tweezers is attributed to the strongly dipolar nature of the merocyanine chromophores and a unique aggregate geometry of four π-stacked chromophores with an alternating arrangement of their dipole moments. The structural assignment of the tetrachromophoric π-stack has been accomplished by MALDI-TOF mass spectrometry and ROESY NMR spectroscopy. Furthermore, molecular modeling studies have accounted for the relationships between the dimerization constants and optical properties of the bimolecular complexes of the present bis(merocyanine) dyes and the structure of the spacer and the positions at which the merocyanine chromophores are attached.}, author = {Lohr, Andreas and Grüne, Matthias and Würthner, Frank}, journal = {Chemistry – A European Journal}, keywords = {myown}, number = 15, pages = {3691–3705}, publisher = {WILEY-VCH Verlag}, title = {Self-Assembly of Bis(merocyanine) Tweezers into Discrete Bimolecular π-Stacks}, volume = 15, year = 2009 }

  %0 Journal Article %1 CHEM:CHEM200802391 %A Lohr, Andreas %A Grüne, Matthias %A Würthner, Frank %D 2009 %I WILEY-VCH Verlag %J Chemistry – A European Journal %N 15 %P 3691--3705 %R 10.1002/chem.200802391 %T Self-Assembly of Bis(merocyanine) Tweezers into Discrete Bimolecular π-Stacks %U http://dx.doi.org/10.1002/chem.200802391 %V 15 %X Dipolar aggregation: Examples of a novel class of tweezer molecules have been constructed through the tethering of two dipolar merocyanine chromophores. The electrostatic-interaction-directed self-assembly of these tweezers affords centrosymmetric bimolecular complexes with a unique aggregate geometry of four π-stacked chromophores (see picture) with an alternating arrangement of their dipole moments and very high dimerization constants, even in the good solvating solvent chloroform. Examples of a novel class of tweezer molecules have been constructed through the tethering of two dipolar merocyanine chromophores by a naphthalenedimethylene or dimethylenediphenylmethane spacer. The electrostatic-interaction-directed self-assembly of these bis(merocyanine) tweezers affords centrosymmetric bimolecular complexes with very high dimerization constants of up to >109 M−1, even in the good solvating solvent chloroform. This pronounced self-association of the bis(merocyanine) tweezers is attributed to the strongly dipolar nature of the merocyanine chromophores and a unique aggregate geometry of four π-stacked chromophores with an alternating arrangement of their dipole moments. The structural assignment of the tetrachromophoric π-stack has been accomplished by MALDI-TOF mass spectrometry and ROESY NMR spectroscopy. Furthermore, molecular modeling studies have accounted for the relationships between the dimerization constants and optical properties of the bimolecular complexes of the present bis(merocyanine) dyes and the structure of the spacer and the positions at which the merocyanine chromophores are attached.
• Outstanding Short‐Circuit Currents in BHJ Solar Cells Based on NIR‐Absorbing Acceptor‐Substituted Squaraines. Mayerhöffer, Ulrich; Deing, Kaja; Gruß, Katrin; Braunschweig, Holger; Meerholz, Klaus; Würthner, Frank. In Angew. Chem. Int. Ed., 48(46), pp. 8776–8779. 2009.
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  @article{mayerhffer2009outstanding, author = {Mayerhöffer, Ulrich and Deing, Kaja and Gruß, Katrin and Braunschweig, Holger and Meerholz, Klaus and Würthner, Frank}, journal = {Angew. Chem. Int. Ed.}, keywords = {myown}, number = 46, pages = {8776 - 8779}, publisher = {WILEY-VCH Verlag}, title = {Outstanding Short‐Circuit Currents in BHJ Solar Cells Based on NIR‐Absorbing Acceptor‐Substituted Squaraines}, volume = 48, year = 2009 }

  %0 Journal Article %1 mayerhffer2009outstanding %A Mayerhöffer, Ulrich %A Deing, Kaja %A Gruß, Katrin %A Braunschweig, Holger %A Meerholz, Klaus %A Würthner, Frank %D 2009 %I WILEY-VCH Verlag %J Angew. Chem. Int. Ed. %N 46 %P 8776 - 8779 %R 10.1002/anie.200903125 %T Outstanding Short‐Circuit Currents in BHJ Solar Cells Based on NIR‐Absorbing Acceptor‐Substituted Squaraines %U https://onlinelibrary.wiley.com/doi/10.1002/anie.200903125 %V 48
• Photoinduced Interactions in a Pyrene-Calix[4]arene-Perylene Bisimide Dye System: Probing Ground-State Conformations with Excited-State Dynamics of Charge Separation and Recombination. Vân Anh, Nguyen; Schlosser, Felix; Groeneveld, Michiel M.; van Stokkum, Ivo H. M.; Würthner, Frank; Williams, René M. In J. Phys. Chem. C., 113(42), pp. 18358–18368. 2009.
  • [ Abstract ]
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  A calix[4]arene scaffold has been functionalized with an electron-accepting perylene bisimide as well as an electron-donating pyrene unit. Steady-state and time-resolved spectroscopy indicate a strong charge-transfer (CT) interaction between these two units in all investigated solvents. The signatures of the radical anion of the perylene bisimide and the radical cation of the pyrene are observed with femtosecond transient absorption spectroscopy. A preferential π-stacked conformation is inferred. In tetrahydrofuran as a solvent ∼25\% of an extended form is invoked. The CT states of these two ground-state populations (π-stacked and extended) have different formation and decay kinetics and result in the spectral distinction of a compact and an extended charge-transfer state upon visible excitation. In the extended conformation, upon UV excitation, pyrene acts as an electron acceptor that is reduced through a photoinduced electron-transfer process by the calix[4]arene. In this conformation the calixarene scaffold is accordingly not an uninvolved linker unit but participates effectively in the electron-transfer processes.

  @article{doi:10.1021/jp9055279, abstract = {A calix[4]arene scaffold has been functionalized with an electron-accepting perylene bisimide as well as an electron-donating pyrene unit. Steady-state and time-resolved spectroscopy indicate a strong charge-transfer (CT) interaction between these two units in all investigated solvents. The signatures of the radical anion of the perylene bisimide and the radical cation of the pyrene are observed with femtosecond transient absorption spectroscopy. A preferential π-stacked conformation is inferred. In tetrahydrofuran as a solvent ∼25\% of an extended form is invoked. The CT states of these two ground-state populations (π-stacked and extended) have different formation and decay kinetics and result in the spectral distinction of a compact and an extended charge-transfer state upon visible excitation. In the extended conformation, upon UV excitation, pyrene acts as an electron acceptor that is reduced through a photoinduced electron-transfer process by the calix[4]arene. In this conformation the calixarene scaffold is accordingly not an uninvolved linker unit but participates effectively in the electron-transfer processes.}, author = {Vân Anh, Nguyen and Schlosser, Felix and Groeneveld, Michiel M. and van Stokkum, Ivo H. M. and Würthner, Frank and Williams, René M.}, journal = {J. Phys. Chem. C.}, keywords = {myown}, number = 42, pages = {18358-18368}, title = {Photoinduced Interactions in a Pyrene-Calix[4]arene-Perylene Bisimide Dye System: Probing Ground-State Conformations with Excited-State Dynamics of Charge Separation and Recombination}, volume = 113, year = 2009 }

  %0 Journal Article %1 doi:10.1021/jp9055279 %A Vân Anh, Nguyen %A Schlosser, Felix %A Groeneveld, Michiel M. %A van Stokkum, Ivo H. M. %A Würthner, Frank %A Williams, René M. %D 2009 %J J. Phys. Chem. C. %N 42 %P 18358-18368 %R 10.1021/jp9055279 %T Photoinduced Interactions in a Pyrene-Calix[4]arene-Perylene Bisimide Dye System: Probing Ground-State Conformations with Excited-State Dynamics of Charge Separation and Recombination %U http://dx.doi.org/10.1021/jp9055279 %V 113 %X A calix[4]arene scaffold has been functionalized with an electron-accepting perylene bisimide as well as an electron-donating pyrene unit. Steady-state and time-resolved spectroscopy indicate a strong charge-transfer (CT) interaction between these two units in all investigated solvents. The signatures of the radical anion of the perylene bisimide and the radical cation of the pyrene are observed with femtosecond transient absorption spectroscopy. A preferential π-stacked conformation is inferred. In tetrahydrofuran as a solvent ∼25\% of an extended form is invoked. The CT states of these two ground-state populations (π-stacked and extended) have different formation and decay kinetics and result in the spectral distinction of a compact and an extended charge-transfer state upon visible excitation. In the extended conformation, upon UV excitation, pyrene acts as an electron acceptor that is reduced through a photoinduced electron-transfer process by the calix[4]arene. In this conformation the calixarene scaffold is accordingly not an uninvolved linker unit but participates effectively in the electron-transfer processes.
• Self-assembly and layer-by-layer deposition of metallosupramolecular perylene bisimide polymers. Stepanenko, Vladimir; Stocker, Michael; Muller, Paul; Buchner, Michael; Würthner, Frank. In J. Mater. Chem., 19(37), pp. 6816–6826. 2009.
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  2,2[prime or minute]:6[prime or minute],2[double prime]-Terpyridine (tpy)-functionalized red and green perylene bisimide (PBI) building blocks were synthesized, and their metal-ion-directed self-assembly was studied in detail by 1H NMR, DOSY NMR, and UV-vis spectroscopy. These studies revealed that the newly synthesized ditopic bis(tpy)-PBI ligands, in which the tpy units are directly connected to PBI moieties at the imide positions, form supramolecular coordination polymers upon addition of one equivalent of Zn(ii) ions. Atomic force microscopy (AFM) investigations confirmed the formation of extended, rigid polymers with average chain lengths of up to 30-35 repeat units. These coordination polymers create closely packed films with linear arrangement on mica and HOPG surfaces. The Zn(ii) centers were mapped by applying current imaging tunnelling spectroscopy (CITS) to the red-coloured polymer deposited on graphite surfaces. An enhanced local density of unoccupied states close to the Fermi energy was observed in positions with metal ions. Alternate multilayer films of two different coordination polymers were prepared by the layer-by-layer deposition technique and surface densities [Gamma] of perylene bisimide chromophores in these films were determined.

  @article{B908011M, abstract = {2{,}2[prime or minute]:6[prime or minute]{,}2[double prime]-Terpyridine (tpy)-functionalized red and green perylene bisimide (PBI) building blocks were synthesized{,} and their metal-ion-directed self-assembly was studied in detail by 1H NMR{,} DOSY NMR{,} and UV-vis spectroscopy. These studies revealed that the newly synthesized ditopic bis(tpy)-PBI ligands{,} in which the tpy units are directly connected to PBI moieties at the imide positions{,} form supramolecular coordination polymers upon addition of one equivalent of Zn(ii) ions. Atomic force microscopy (AFM) investigations confirmed the formation of extended{,} rigid polymers with average chain lengths of up to 30-35 repeat units. These coordination polymers create closely packed films with linear arrangement on mica and HOPG surfaces. The Zn(ii) centers were mapped by applying current imaging tunnelling spectroscopy (CITS) to the red-coloured polymer deposited on graphite surfaces. An enhanced local density of unoccupied states close to the Fermi energy was observed in positions with metal ions. Alternate multilayer films of two different coordination polymers were prepared by the layer-by-layer deposition technique and surface densities [Gamma] of perylene bisimide chromophores in these films were determined.}, author = {Stepanenko, Vladimir and Stocker, Michael and Muller, Paul and Buchner, Michael and Würthner, Frank}, journal = {J. Mater. Chem.}, keywords = {myown}, number = 37, pages = {6816-6826}, publisher = {The Royal Society of Chemistry}, title = {Self-assembly and layer-by-layer deposition of metallosupramolecular perylene bisimide polymers}, volume = 19, year = 2009 }

  %0 Journal Article %1 B908011M %A Stepanenko, Vladimir %A Stocker, Michael %A Muller, Paul %A Buchner, Michael %A Würthner, Frank %D 2009 %I The Royal Society of Chemistry %J J. Mater. Chem. %N 37 %P 6816-6826 %R 10.1039/B908011M %T Self-assembly and layer-by-layer deposition of metallosupramolecular perylene bisimide polymers %U http://dx.doi.org/10.1039/B908011M %V 19 %X 2,2[prime or minute]:6[prime or minute],2[double prime]-Terpyridine (tpy)-functionalized red and green perylene bisimide (PBI) building blocks were synthesized, and their metal-ion-directed self-assembly was studied in detail by 1H NMR, DOSY NMR, and UV-vis spectroscopy. These studies revealed that the newly synthesized ditopic bis(tpy)-PBI ligands, in which the tpy units are directly connected to PBI moieties at the imide positions, form supramolecular coordination polymers upon addition of one equivalent of Zn(ii) ions. Atomic force microscopy (AFM) investigations confirmed the formation of extended, rigid polymers with average chain lengths of up to 30-35 repeat units. These coordination polymers create closely packed films with linear arrangement on mica and HOPG surfaces. The Zn(ii) centers were mapped by applying current imaging tunnelling spectroscopy (CITS) to the red-coloured polymer deposited on graphite surfaces. An enhanced local density of unoccupied states close to the Fermi energy was observed in positions with metal ions. Alternate multilayer films of two different coordination polymers were prepared by the layer-by-layer deposition technique and surface densities [Gamma] of perylene bisimide chromophores in these films were determined.
• Synthetic Routes to Core-fluorinated Perylene Bisimide Dyes and their Properties. Schmidt, R.; Osswald, P.; Könemann, M.; Würthner, Frank. In Z. Naturforsch., 64b, pp. 735–746. 2009.
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  @article{schmidt2009synthetic, author = {Schmidt, R. and Osswald, P. and Könemann, M. and Würthner, Frank}, journal = {Z. Naturforsch.}, keywords = {myown}, pages = {735-746}, title = {Synthetic Routes to Core-fluorinated Perylene Bisimide Dyes and their Properties}, volume = {64b}, year = 2009 }

  %0 Journal Article %1 schmidt2009synthetic %A Schmidt, R. %A Osswald, P. %A Könemann, M. %A Würthner, Frank %D 2009 %J Z. Naturforsch. %P 735-746 %T Synthetic Routes to Core-fluorinated Perylene Bisimide Dyes and their Properties %V 64b
• Unconventional hydrogen-bond-directed hierarchical co-assembly between perylene bisimide and azobenzene-functionalized melamine. Yagai, Shiki; Hamamura, Saori; Wang, Hao; Stepanenko, Vladimir; Seki, Tomohiro; Unoike, Kanako; Kikkawa, Yoshihiro; Karatsu, Takashi; Kitamura, Akihide; Würthner, Frank. In Org. Biomol. Chem., 7(19), pp. 3926–3929. 2009.
  • [ Abstract ]
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  Co-assembly of ditopic perylene bisimide and azobenzene-functionalized melamine occurs with an unconventional stoichiometric ratio, providing well-defined nanostructures with a helically-coiled architecture where perylene chromophores are packed in desirable J-type arrangements.

  @article{B912809C, abstract = {Co-assembly of ditopic perylene bisimide and azobenzene-functionalized melamine occurs with an unconventional stoichiometric ratio{,} providing well-defined nanostructures with a helically-coiled architecture where perylene chromophores are packed in desirable J-type arrangements.}, author = {Yagai, Shiki and Hamamura, Saori and Wang, Hao and Stepanenko, Vladimir and Seki, Tomohiro and Unoike, Kanako and Kikkawa, Yoshihiro and Karatsu, Takashi and Kitamura, Akihide and Würthner, Frank}, journal = {Org. Biomol. Chem.}, keywords = {myown}, number = 19, pages = {3926-3929}, publisher = {The Royal Society of Chemistry}, title = {Unconventional hydrogen-bond-directed hierarchical co-assembly between perylene bisimide and azobenzene-functionalized melamine}, volume = 7, year = 2009 }

  %0 Journal Article %1 B912809C %A Yagai, Shiki %A Hamamura, Saori %A Wang, Hao %A Stepanenko, Vladimir %A Seki, Tomohiro %A Unoike, Kanako %A Kikkawa, Yoshihiro %A Karatsu, Takashi %A Kitamura, Akihide %A Würthner, Frank %D 2009 %I The Royal Society of Chemistry %J Org. Biomol. Chem. %N 19 %P 3926-3929 %R 10.1039/B912809C %T Unconventional hydrogen-bond-directed hierarchical co-assembly between perylene bisimide and azobenzene-functionalized melamine %U http://dx.doi.org/10.1039/B912809C %V 7 %X Co-assembly of ditopic perylene bisimide and azobenzene-functionalized melamine occurs with an unconventional stoichiometric ratio, providing well-defined nanostructures with a helically-coiled architecture where perylene chromophores are packed in desirable J-type arrangements.
• Zinc chlorins for artificial light-harvesting self-assemble into antiparallel stacks forming a microcrystalline solid-state material. Ganapathy, Swapna; Sengupta, Sanchita; Wawrzyniak, Piotr K.; Huber, Valerie; Buda, Francesco; Baumeister, Ute; Würthner, Frank; de Groot, Huub J. M. In Proceedings of the National Academy of Sciences, 106(28), pp. 11472–11477. 2009.
  • [ Abstract ]
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  We introduce a concept to solve the structure of a microcrystalline material in the solid-state at natural abundance without access to distance constraints, using magic angle spinning (MAS) NMR spectroscopy in conjunction with X-ray powder diffraction and DFT calculations. The method is applied to a novel class of materials that form (semi)conductive 1D wires for supramolecular electronics and artificial light-harvesting. The zinc chlorins 3-devinyl-31-hydroxymethyl-132-demethoxycarbonylpheophorbide a (3′,5′-bis-dodecyloxy)benzyl ester zinc complex 1 and 3-devinyl-31-methoxymethyl-132-demethoxycarbonylpheophorbide a (3′,5′-bis-dodecyloxy)benzyl ester zinc complex 2, self-assemble into extended excitonically coupled chromophore stacks. 1H-13C heteronuclear dipolar correlation MAS NMR experiments provided the 1H resonance assignment of the chlorin rings that allowed accurate probing of ring currents related to the stacking of macrocycles. DFT ring-current shift calculations revealed that both chlorins self-assemble in antiparallel π-stacks in planar layers in the solid-state. Concomitantly, X-ray powder diffraction measurements for chlorin 2 at 80 °C revealed a 3D lattice for the mesoscale packing that matches molecular mechanics optimized aggregate models. For chlorin 2 the stacks alternate with a periodicity of 0.68 nm and a 3D unit cell with an approximate volume of 6.28 nm3 containing 4 molecules, which is consistent with space group P21221.

  @article{Ganapathy14072009, abstract = {We introduce a concept to solve the structure of a microcrystalline material in the solid-state at natural abundance without access to distance constraints, using magic angle spinning (MAS) NMR spectroscopy in conjunction with X-ray powder diffraction and DFT calculations. The method is applied to a novel class of materials that form (semi)conductive 1D wires for supramolecular electronics and artificial light-harvesting. The zinc chlorins 3-devinyl-31-hydroxymethyl-132-demethoxycarbonylpheophorbide a (3′,5′-bis-dodecyloxy)benzyl ester zinc complex 1 and 3-devinyl-31-methoxymethyl-132-demethoxycarbonylpheophorbide a (3′,5′-bis-dodecyloxy)benzyl ester zinc complex 2, self-assemble into extended excitonically coupled chromophore stacks. 1H-13C heteronuclear dipolar correlation MAS NMR experiments provided the 1H resonance assignment of the chlorin rings that allowed accurate probing of ring currents related to the stacking of macrocycles. DFT ring-current shift calculations revealed that both chlorins self-assemble in antiparallel π-stacks in planar layers in the solid-state. Concomitantly, X-ray powder diffraction measurements for chlorin 2 at 80 °C revealed a 3D lattice for the mesoscale packing that matches molecular mechanics optimized aggregate models. For chlorin 2 the stacks alternate with a periodicity of 0.68 nm and a 3D unit cell with an approximate volume of 6.28 nm3 containing 4 molecules, which is consistent with space group P21221.}, author = {Ganapathy, Swapna and Sengupta, Sanchita and Wawrzyniak, Piotr K. and Huber, Valerie and Buda, Francesco and Baumeister, Ute and Würthner, Frank and de Groot, Huub J. M.}, journal = {Proceedings of the National Academy of Sciences}, keywords = {myown}, number = 28, pages = {11472-11477}, title = {Zinc chlorins for artificial light-harvesting self-assemble into antiparallel stacks forming a microcrystalline solid-state material}, volume = 106, year = 2009 }

  %0 Journal Article %1 Ganapathy14072009 %A Ganapathy, Swapna %A Sengupta, Sanchita %A Wawrzyniak, Piotr K. %A Huber, Valerie %A Buda, Francesco %A Baumeister, Ute %A Würthner, Frank %A de Groot, Huub J. M. %D 2009 %J Proceedings of the National Academy of Sciences %N 28 %P 11472-11477 %R 10.1073/pnas.0811872106 %T Zinc chlorins for artificial light-harvesting self-assemble into antiparallel stacks forming a microcrystalline solid-state material %U http://www.pnas.org/content/106/28/11472.abstract %V 106 %X We introduce a concept to solve the structure of a microcrystalline material in the solid-state at natural abundance without access to distance constraints, using magic angle spinning (MAS) NMR spectroscopy in conjunction with X-ray powder diffraction and DFT calculations. The method is applied to a novel class of materials that form (semi)conductive 1D wires for supramolecular electronics and artificial light-harvesting. The zinc chlorins 3-devinyl-31-hydroxymethyl-132-demethoxycarbonylpheophorbide a (3′,5′-bis-dodecyloxy)benzyl ester zinc complex 1 and 3-devinyl-31-methoxymethyl-132-demethoxycarbonylpheophorbide a (3′,5′-bis-dodecyloxy)benzyl ester zinc complex 2, self-assemble into extended excitonically coupled chromophore stacks. 1H-13C heteronuclear dipolar correlation MAS NMR experiments provided the 1H resonance assignment of the chlorin rings that allowed accurate probing of ring currents related to the stacking of macrocycles. DFT ring-current shift calculations revealed that both chlorins self-assemble in antiparallel π-stacks in planar layers in the solid-state. Concomitantly, X-ray powder diffraction measurements for chlorin 2 at 80 °C revealed a 3D lattice for the mesoscale packing that matches molecular mechanics optimized aggregate models. For chlorin 2 the stacks alternate with a periodicity of 0.68 nm and a 3D unit cell with an approximate volume of 6.28 nm3 containing 4 molecules, which is consistent with space group P21221.
• Dendritic oligothiophene-perylene bisimide hybrids: synthesis, optical and electrochemical properties. Fischer, Markus K. R.; Kaiser, Theo E.; Würthner, Frank; Bauerle, Peter. In J. Mater. Chem., 19(8), pp. 1129–1141. 2009.
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  Novel dendritic oligothiophene-perylene bisimide hybrid (DOTPBI) systems were investigated. Perylene bisimide (PBI) derivatives with phenoxy spacers bearing dendritic oligothiophenes (DOT) up to the third generation (G3) in the bay position, with an increasing number of conjugated thiophene units have been synthesized and characterized as novel functional materials. Investigation of the optoelectronic properties revealed that the perylene core and dendritic oligothiophene units are electronically decoupled. In the DOTPBIs intramolecular fluorescence resonance energy transfer (FRET) and photoinduced electron transfer (PET) from the DOT to the PBI moiety have been investigated by various optical measurements, revealing that the PET process is facilitated with increasing DOT generation and donor strength. Electropolymerization led to interesting cross-linked donor acceptor-type conducting polymer films.

  @article{B817158K, abstract = {Novel dendritic oligothiophene-perylene bisimide hybrid (DOTPBI) systems were investigated. Perylene bisimide (PBI) derivatives with phenoxy spacers bearing dendritic oligothiophenes (DOT) up to the third generation (G3) in the bay position, with an increasing number of conjugated thiophene units have been synthesized and characterized as novel functional materials. Investigation of the optoelectronic properties revealed that the perylene core and dendritic oligothiophene units are electronically decoupled. In the DOTPBIs intramolecular fluorescence resonance energy transfer (FRET) and photoinduced electron transfer (PET) from the DOT to the PBI moiety have been investigated by various optical measurements, revealing that the PET process is facilitated with increasing DOT generation and donor strength. Electropolymerization led to interesting cross-linked donor acceptor-type conducting polymer films.}, author = {Fischer, Markus K. R. and Kaiser, Theo E. and Würthner, Frank and Bauerle, Peter}, journal = {J. Mater. Chem.}, keywords = {myown}, number = 8, pages = {1129-1141}, publisher = {The Royal Society of Chemistry}, title = {Dendritic oligothiophene-perylene bisimide hybrids: synthesis, optical and electrochemical properties}, volume = 19, year = 2009 }

  %0 Journal Article %1 B817158K %A Fischer, Markus K. R. %A Kaiser, Theo E. %A Würthner, Frank %A Bauerle, Peter %D 2009 %I The Royal Society of Chemistry %J J. Mater. Chem. %N 8 %P 1129-1141 %R 10.1039/B817158K %T Dendritic oligothiophene-perylene bisimide hybrids: synthesis, optical and electrochemical properties %U http://dx.doi.org/10.1039/B817158K %V 19 %X Novel dendritic oligothiophene-perylene bisimide hybrid (DOTPBI) systems were investigated. Perylene bisimide (PBI) derivatives with phenoxy spacers bearing dendritic oligothiophenes (DOT) up to the third generation (G3) in the bay position, with an increasing number of conjugated thiophene units have been synthesized and characterized as novel functional materials. Investigation of the optoelectronic properties revealed that the perylene core and dendritic oligothiophene units are electronically decoupled. In the DOTPBIs intramolecular fluorescence resonance energy transfer (FRET) and photoinduced electron transfer (PET) from the DOT to the PBI moiety have been investigated by various optical measurements, revealing that the PET process is facilitated with increasing DOT generation and donor strength. Electropolymerization led to interesting cross-linked donor acceptor-type conducting polymer films.
• Vibronic Transitions and Quantum Dynamics in Molecular Oligomers: A Theoretical Analysis with an Application to Aggregates of Perylene Bisimides. Seibt, J.; Winkler, T.; Renziehausen, K.; Dehm, V.; Würthner, F.; Meyer, H.-D.; Engel, V. In J. Phys. Chem. A, 113(48), pp. 13475–13482. 2009.

  PMID: 19831416
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  Vibronic absorption spectra of molecular aggregates consisting of up to N = 9 monomer units are calculated employing methods of time-dependent quantum mechanics. Taking one vibrational degree of freedom for each monomer into account and treating one-exciton excited electronic states leads to a problem with N vibrations and N electronically coupled states. The demanding quantum propagation is carried out within the multiconfiguration time-depended Hartree method (MCTDH). Spectral features of and population transfer in the aggregates are analyzed as a function of the aggregate size and the strength of the electronic coupling. With a model for oligomers of perylene bisimides, it is shown how measured temperature-dependent absorption spectra correlate with the aggregate size. Furthermore, the exciton localization and dynamics in these aggregates are investigated.

  @article{doi:10.1021/jp904892v, abstract = {Vibronic absorption spectra of molecular aggregates consisting of up to N = 9 monomer units are calculated employing methods of time-dependent quantum mechanics. Taking one vibrational degree of freedom for each monomer into account and treating one-exciton excited electronic states leads to a problem with N vibrations and N electronically coupled states. The demanding quantum propagation is carried out within the multiconfiguration time-depended Hartree method (MCTDH). Spectral features of and population transfer in the aggregates are analyzed as a function of the aggregate size and the strength of the electronic coupling. With a model for oligomers of perylene bisimides, it is shown how measured temperature-dependent absorption spectra correlate with the aggregate size. Furthermore, the exciton localization and dynamics in these aggregates are investigated.}, author = {Seibt, J. and Winkler, T. and Renziehausen, K. and Dehm, V. and Würthner, F. and Meyer, H.-D. and Engel, V.}, journal = {J. Phys. Chem. A}, keywords = {myown}, note = {PMID: 19831416}, number = 48, pages = {13475-13482}, title = {Vibronic Transitions and Quantum Dynamics in Molecular Oligomers: A Theoretical Analysis with an Application to Aggregates of Perylene Bisimides}, volume = 113, year = 2009 }

  %0 Journal Article %1 doi:10.1021/jp904892v %A Seibt, J. %A Winkler, T. %A Renziehausen, K. %A Dehm, V. %A Würthner, F. %A Meyer, H.-D. %A Engel, V. %D 2009 %J J. Phys. Chem. A %N 48 %P 13475-13482 %R 10.1021/jp904892v %T Vibronic Transitions and Quantum Dynamics in Molecular Oligomers: A Theoretical Analysis with an Application to Aggregates of Perylene Bisimides %U http://dx.doi.org/10.1021/jp904892v %V 113 %X Vibronic absorption spectra of molecular aggregates consisting of up to N = 9 monomer units are calculated employing methods of time-dependent quantum mechanics. Taking one vibrational degree of freedom for each monomer into account and treating one-exciton excited electronic states leads to a problem with N vibrations and N electronically coupled states. The demanding quantum propagation is carried out within the multiconfiguration time-depended Hartree method (MCTDH). Spectral features of and population transfer in the aggregates are analyzed as a function of the aggregate size and the strength of the electronic coupling. With a model for oligomers of perylene bisimides, it is shown how measured temperature-dependent absorption spectra correlate with the aggregate size. Furthermore, the exciton localization and dynamics in these aggregates are investigated.
• Core-Tetrasubstituted Naphthalene Diimides by Stille Cross-Coupling Reactions and Characterization of Their Optical and Redox Properties. Suraru, Sabin-Lucian; Würthner, Frank. G. T. V. Stuttgart (ed.). 2009.
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  The palladium-catalyzed cross-coupling reaction of 2,3,6,7-tetrabromonaphthalene diimide with various aryl- and alkynylstannanes afforded a series of hitherto unknown tetraaryl- and tetraethynyl-substituted naphthalene diimides (NDIs). UV/Vis spectroscopic studies revealed that the absorption maxima of ethynyl-substituted NDIs are significantly bathochromically shifted compared to those of unsubstituted and tetraaryl-substituted NDIs. Cyclic voltammetry investigations showed that ethynyl substituents shift the reduction potentials of NDIs anodically, thus these NDI derivatives are interesting candidates for air-stable n-channel organic field-effect transistors.

  @article{suraru2009coretetrasubstituted, abstract = {The palladium-catalyzed cross-coupling reaction of 2,3,6,7-tetrabromonaphthalene diimide with various aryl- and alkynylstannanes afforded a series of hitherto unknown tetraaryl- and tetraethynyl-substituted naphthalene diimides (NDIs). UV/Vis spectroscopic studies revealed that the absorption maxima of ethynyl-substituted NDIs are significantly bathochromically shifted compared to those of unsubstituted and tetraaryl-substituted NDIs. Cyclic voltammetry investigations showed that ethynyl substituents shift the reduction potentials of NDIs anodically, thus these NDI derivatives are interesting candidates for air-stable n-channel organic field-effect transistors.}, author = {Suraru, Sabin-Lucian and Würthner, Frank}, editor = {Stuttgart, Georg Thieme Verlag}, keywords = {arylenes}, title = {Core-Tetrasubstituted Naphthalene Diimides by Stille Cross-Coupling Reactions and Characterization of Their Optical and Redox Properties}, year = 2009 }

  %0 Journal Article %1 suraru2009coretetrasubstituted %A Suraru, Sabin-Lucian %A Würthner, Frank %D 2009 %E Stuttgart, Georg Thieme Verlag %R 10.1055/s-0029-1216785 %T Core-Tetrasubstituted Naphthalene Diimides by Stille Cross-Coupling Reactions and Characterization of Their Optical and Redox Properties %U https://www.thieme-connect.de/DOI/DOI?10.1055/s-0029-1216785 %X The palladium-catalyzed cross-coupling reaction of 2,3,6,7-tetrabromonaphthalene diimide with various aryl- and alkynylstannanes afforded a series of hitherto unknown tetraaryl- and tetraethynyl-substituted naphthalene diimides (NDIs). UV/Vis spectroscopic studies revealed that the absorption maxima of ethynyl-substituted NDIs are significantly bathochromically shifted compared to those of unsubstituted and tetraaryl-substituted NDIs. Cyclic voltammetry investigations showed that ethynyl substituents shift the reduction potentials of NDIs anodically, thus these NDI derivatives are interesting candidates for air-stable n-channel organic field-effect transistors.
• X-ray/Atomic Force Microscopy Study of the Temperature-Dependent Multilayer Structure of PTCDI-C8 Films on SiO2. Krauss, Tobias N.; Barrena, Esther; de Oteyza, Dimas G.; Zhang, Xue N.; Major, János; Dehm, Volker; Würthner, Frank; Dosch, Helmut. In J. Phys. Chem. C., 113(11), pp. 4502–4506. 2009.
  • [ Abstract ]
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  Combining atomic force microscopy, X-ray specular reflection, and grazing incidence X-ray diffraction experiments provides a thorough characterization of the structural properties of PTCDI-C8 films on native silicon dioxide as a function of both growth and post-annealing temperatures. We disclose that monomolecular islands and terraces are polycrystalline with lateral sizes of only ∼280 Å. While the lateral size of the crystallites remains unaffected by an increase of the growth temperature, the ordering along the surface normal is greatly enhanced, thereby reducing the density of topographical grain boundaries. Similarly, optimal post-annealing temperatures cause a better vertical ordering of the multilayer. From a detailed analysis of the X-ray reflectivity as obtained for the best ordered film, we provide accurate information on the vertical structure in the thin film and determine the tilt of the perylene cores.

  @article{doi:10.1021/jp808037w, abstract = {Combining atomic force microscopy, X-ray specular reflection, and grazing incidence X-ray diffraction experiments provides a thorough characterization of the structural properties of PTCDI-C8 films on native silicon dioxide as a function of both growth and post-annealing temperatures. We disclose that monomolecular islands and terraces are polycrystalline with lateral sizes of only ∼280 Å. While the lateral size of the crystallites remains unaffected by an increase of the growth temperature, the ordering along the surface normal is greatly enhanced, thereby reducing the density of topographical grain boundaries. Similarly, optimal post-annealing temperatures cause a better vertical ordering of the multilayer. From a detailed analysis of the X-ray reflectivity as obtained for the best ordered film, we provide accurate information on the vertical structure in the thin film and determine the tilt of the perylene cores.}, author = {Krauss, Tobias N. and Barrena, Esther and de Oteyza, Dimas G. and Zhang, Xue N. and Major, János and Dehm, Volker and Würthner, Frank and Dosch, Helmut}, journal = {J. Phys. Chem. C.}, keywords = {myown}, number = 11, pages = {4502-4506}, title = {X-ray/Atomic Force Microscopy Study of the Temperature-Dependent Multilayer Structure of PTCDI-C8 Films on SiO2}, volume = 113, year = 2009 }

  %0 Journal Article %1 doi:10.1021/jp808037w %A Krauss, Tobias N. %A Barrena, Esther %A de Oteyza, Dimas G. %A Zhang, Xue N. %A Major, János %A Dehm, Volker %A Würthner, Frank %A Dosch, Helmut %D 2009 %J J. Phys. Chem. C. %N 11 %P 4502-4506 %R 10.1021/jp808037w %T X-ray/Atomic Force Microscopy Study of the Temperature-Dependent Multilayer Structure of PTCDI-C8 Films on SiO2 %U http://dx.doi.org/10.1021/jp808037w %V 113 %X Combining atomic force microscopy, X-ray specular reflection, and grazing incidence X-ray diffraction experiments provides a thorough characterization of the structural properties of PTCDI-C8 films on native silicon dioxide as a function of both growth and post-annealing temperatures. We disclose that monomolecular islands and terraces are polycrystalline with lateral sizes of only ∼280 Å. While the lateral size of the crystallites remains unaffected by an increase of the growth temperature, the ordering along the surface normal is greatly enhanced, thereby reducing the density of topographical grain boundaries. Similarly, optimal post-annealing temperatures cause a better vertical ordering of the multilayer. From a detailed analysis of the X-ray reflectivity as obtained for the best ordered film, we provide accurate information on the vertical structure in the thin film and determine the tilt of the perylene cores.
• Interplay between Energetic and Kinetic Factors on the Ambient Stability of n-Channel Organic Transistors Based on Perylene Diimide Derivatives. Oh, Joon Hak; Sun, Ya-Sen; Schmidt, Rüdiger; Toney, Michael F.; Nordlund, Dennis; Könemann, Martin; Würthner, Frank; Bao, Zhenan. In Chemistry of Materials, 21(22), pp. 5508–5518. 2009.
  • [ Abstract ]
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  The effects of the interplay between energetic and kinetic factors on the air stability of n-channel organic thin-film transistors (OTFTs) were studied using two perylene diimide (PDI) compounds with distinctly different lowest unoccupied molecular orbital (LUMO) levels. On the basis of the empirical energy level windows, one compound (N,N′-bis(2,2,3,3,4,4,5,5,5-nonafluoropentyl)-3,4:9,10-tetracarboxylic acid diimide (PDI-F): −3.84 eV) is at the onset region for air stability, whereas the other (N,N′-bis(cyclohexyl)-1,7-dicyano-perylene-3,4:9,10-tetracarboxylic acid diimide (PDI-CN2): −4.33 eV) is in the air-stable region. Charge-transport behaviors under an inert atmosphere and in air were investigated as a function of active layer thickness. Charge transport in air was greatly affected by the active layer thickness for both compounds, an effect that has been overlooked so far. The ambient stability of the air-unstable PDI-F TFTs increased significantly for thicknesses over ∼10 monolayers (ML). Surprisingly, the previously considered “air-stable” PDI-CN2 TFTs were not stable in air if the active layer thickness was less than ∼4 ML. The molecular packing and orientation of the PDI thin films were investigated using grazing incidence X-ray diffraction (GIXD) and near-edge X-ray absorption fine structure (NEXAFS). We found that the minimum thickness required for air stability is closely related to the LUMO level, film morphology, and film growth mode.

  @article{doi:10.1021/cm902531d, abstract = {The effects of the interplay between energetic and kinetic factors on the air stability of n-channel organic thin-film transistors (OTFTs) were studied using two perylene diimide (PDI) compounds with distinctly different lowest unoccupied molecular orbital (LUMO) levels. On the basis of the empirical energy level windows, one compound (N,N′-bis(2,2,3,3,4,4,5,5,5-nonafluoropentyl)-3,4:9,10-tetracarboxylic acid diimide (PDI-F): −3.84 eV) is at the onset region for air stability, whereas the other (N,N′-bis(cyclohexyl)-1,7-dicyano-perylene-3,4:9,10-tetracarboxylic acid diimide (PDI-CN2): −4.33 eV) is in the air-stable region. Charge-transport behaviors under an inert atmosphere and in air were investigated as a function of active layer thickness. Charge transport in air was greatly affected by the active layer thickness for both compounds, an effect that has been overlooked so far. The ambient stability of the air-unstable PDI-F TFTs increased significantly for thicknesses over ∼10 monolayers (ML). Surprisingly, the previously considered “air-stable” PDI-CN2 TFTs were not stable in air if the active layer thickness was less than ∼4 ML. The molecular packing and orientation of the PDI thin films were investigated using grazing incidence X-ray diffraction (GIXD) and near-edge X-ray absorption fine structure (NEXAFS). We found that the minimum thickness required for air stability is closely related to the LUMO level, film morphology, and film growth mode.}, author = {Oh, Joon Hak and Sun, Ya-Sen and Schmidt, Rüdiger and Toney, Michael F. and Nordlund, Dennis and Könemann, Martin and Würthner, Frank and Bao, Zhenan}, journal = {Chemistry of Materials}, keywords = {myown}, number = 22, pages = {5508-5518}, title = {Interplay between Energetic and Kinetic Factors on the Ambient Stability of n-Channel Organic Transistors Based on Perylene Diimide Derivatives}, volume = 21, year = 2009 }

  %0 Journal Article %1 doi:10.1021/cm902531d %A Oh, Joon Hak %A Sun, Ya-Sen %A Schmidt, Rüdiger %A Toney, Michael F. %A Nordlund, Dennis %A Könemann, Martin %A Würthner, Frank %A Bao, Zhenan %D 2009 %J Chemistry of Materials %N 22 %P 5508-5518 %R 10.1021/cm902531d %T Interplay between Energetic and Kinetic Factors on the Ambient Stability of n-Channel Organic Transistors Based on Perylene Diimide Derivatives %U http://dx.doi.org/10.1021/cm902531d %V 21 %X The effects of the interplay between energetic and kinetic factors on the air stability of n-channel organic thin-film transistors (OTFTs) were studied using two perylene diimide (PDI) compounds with distinctly different lowest unoccupied molecular orbital (LUMO) levels. On the basis of the empirical energy level windows, one compound (N,N′-bis(2,2,3,3,4,4,5,5,5-nonafluoropentyl)-3,4:9,10-tetracarboxylic acid diimide (PDI-F): −3.84 eV) is at the onset region for air stability, whereas the other (N,N′-bis(cyclohexyl)-1,7-dicyano-perylene-3,4:9,10-tetracarboxylic acid diimide (PDI-CN2): −4.33 eV) is in the air-stable region. Charge-transport behaviors under an inert atmosphere and in air were investigated as a function of active layer thickness. Charge transport in air was greatly affected by the active layer thickness for both compounds, an effect that has been overlooked so far. The ambient stability of the air-unstable PDI-F TFTs increased significantly for thicknesses over ∼10 monolayers (ML). Surprisingly, the previously considered “air-stable” PDI-CN2 TFTs were not stable in air if the active layer thickness was less than ∼4 ML. The molecular packing and orientation of the PDI thin films were investigated using grazing incidence X-ray diffraction (GIXD) and near-edge X-ray absorption fine structure (NEXAFS). We found that the minimum thickness required for air stability is closely related to the LUMO level, film morphology, and film growth mode.
• Understanding Ground- and Excited-State Properties of Perylene Tetracarboxylic Acid Bisimide Crystals by Means of Quantum Chemical Computations. Zhao, Hong-Mei; Pfister, Johannes; Settels, Volker; Renz, Manuel; Kaupp, Martin; Dehm, Volker C.; Würthner, Frank; Fink, Reinhold F.; Engels, Bernd. In J. Am. Chem. Soc., 131(43), pp. 15660–15668. 2009.

  PMID: 19860479
  • [ Abstract ]
  • [ BibTeX ]
  • [ EndNote ]
  • [ DOI ]
  Quantum chemical protocols explaining the crystal structures and the visible light absorption properties of 3,4:9,10-perylene tetracarboxylic acid bisimide (PBI) derivates are proposed. Dispersion-corrected density functional theory has provided an intermolecular potential energy of PBI dimers showing several energetically low-lying minima, which corresponds well with the packing of different PBI dyes in the solid state. While the dispersion interaction is found to be crucial for the binding strength, the minimum structures of the PESs are best explained by electrostatic interactions. Furthermore, a method is introduced, which reproduces the photon energies at the absorption maxima of PBI pigments within 0.1 eV. It is based on time-dependent Hartree−Fock (TD-HF) excitation energies calculated for PBI dimers with the next-neighbor arrangement in the pigment and incorporates crystal packing effects. This success provides clear evidence that the electronically excited states, which determine the color of these pigments, have no significant charge-transfer character. The developed protocols can be applied in a routine manner to understand and to predict the properties of such pigments, which are important materials for organic solar cells and (opto-)electronic devices.

  @article{doi:10.1021/ja902512e, abstract = {Quantum chemical protocols explaining the crystal structures and the visible light absorption properties of 3,4:9,10-perylene tetracarboxylic acid bisimide (PBI) derivates are proposed. Dispersion-corrected density functional theory has provided an intermolecular potential energy of PBI dimers showing several energetically low-lying minima, which corresponds well with the packing of different PBI dyes in the solid state. While the dispersion interaction is found to be crucial for the binding strength, the minimum structures of the PESs are best explained by electrostatic interactions. Furthermore, a method is introduced, which reproduces the photon energies at the absorption maxima of PBI pigments within 0.1 eV. It is based on time-dependent Hartree−Fock (TD-HF) excitation energies calculated for PBI dimers with the next-neighbor arrangement in the pigment and incorporates crystal packing effects. This success provides clear evidence that the electronically excited states, which determine the color of these pigments, have no significant charge-transfer character. The developed protocols can be applied in a routine manner to understand and to predict the properties of such pigments, which are important materials for organic solar cells and (opto-)electronic devices.}, author = {Zhao, Hong-Mei and Pfister, Johannes and Settels, Volker and Renz, Manuel and Kaupp, Martin and Dehm, Volker C. and Würthner, Frank and Fink, Reinhold F. and Engels, Bernd}, journal = {J. Am. Chem. Soc.}, keywords = {myown}, note = {PMID: 19860479}, number = 43, pages = {15660-15668}, title = {Understanding Ground- and Excited-State Properties of Perylene Tetracarboxylic Acid Bisimide Crystals by Means of Quantum Chemical Computations}, volume = 131, year = 2009 }

  %0 Journal Article %1 doi:10.1021/ja902512e %A Zhao, Hong-Mei %A Pfister, Johannes %A Settels, Volker %A Renz, Manuel %A Kaupp, Martin %A Dehm, Volker C. %A Würthner, Frank %A Fink, Reinhold F. %A Engels, Bernd %D 2009 %J J. Am. Chem. Soc. %N 43 %P 15660-15668 %R 10.1021/ja902512e %T Understanding Ground- and Excited-State Properties of Perylene Tetracarboxylic Acid Bisimide Crystals by Means of Quantum Chemical Computations %U http://dx.doi.org/10.1021/ja902512e %V 131 %X Quantum chemical protocols explaining the crystal structures and the visible light absorption properties of 3,4:9,10-perylene tetracarboxylic acid bisimide (PBI) derivates are proposed. Dispersion-corrected density functional theory has provided an intermolecular potential energy of PBI dimers showing several energetically low-lying minima, which corresponds well with the packing of different PBI dyes in the solid state. While the dispersion interaction is found to be crucial for the binding strength, the minimum structures of the PESs are best explained by electrostatic interactions. Furthermore, a method is introduced, which reproduces the photon energies at the absorption maxima of PBI pigments within 0.1 eV. It is based on time-dependent Hartree−Fock (TD-HF) excitation energies calculated for PBI dimers with the next-neighbor arrangement in the pigment and incorporates crystal packing effects. This success provides clear evidence that the electronically excited states, which determine the color of these pigments, have no significant charge-transfer character. The developed protocols can be applied in a routine manner to understand and to predict the properties of such pigments, which are important materials for organic solar cells and (opto-)electronic devices.
• Bay-substituted perylene bisimides: Twisted fluorophores for supramolecular chemistry. Würthner, Frank. In The Scientific Journal of IUPAC, Pure Appl. Chem.(78), pp. 2341–2350. 2009.
  • [ Abstract ]
  • [ BibTeX ]
  • [ EndNote ]
  • [ DOI ]
  Perylene bisimides bearing four aryloxy substituents in the 1,6,7,12 positions (so-called bay area) and two receptor units at the imide nitrogens are most useful fluorescent building blocks for the realization of a broad variety of supramolecular architectures. As discussed in this review, this versatility is not only due to the outstanding fluorescence properties of these dyes with quantum yields close to unity, but also a consequence of pronounced twisting of the π-system with an inversion barrier of around 60 kJ/mol (leading to atropisomerism) and conformational flexibility of aryloxy units. The latter two properties endow these dyes with high solubility even in least polar aliphatic solvents and enable the dyes to maintain a distance of >4 Å in their supramolecular assemblies. This feature particularly reduces the, otherwise often observed, fluorescence quenching in dye aggregates. Thus, bright luminescent cyclic and polymeric supramolecular architectures have become available from these dyes by hydrogen-bond and metal-ion directed self-assembly. In those cases where additional π-π-stacking interactions come into play, luminescent organogels and liquid crystals are obtained.

  @article{wrthner2009baysubstituted, abstract = {Perylene bisimides bearing four aryloxy substituents in the 1,6,7,12 positions (so-called bay area) and two receptor units at the imide nitrogens are most useful fluorescent building blocks for the realization of a broad variety of supramolecular architectures. As discussed in this review, this versatility is not only due to the outstanding fluorescence properties of these dyes with quantum yields close to unity, but also a consequence of pronounced twisting of the π-system with an inversion barrier of around 60 kJ/mol (leading to atropisomerism) and conformational flexibility of aryloxy units. The latter two properties endow these dyes with high solubility even in least polar aliphatic solvents and enable the dyes to maintain a distance of >4 Å in their supramolecular assemblies. This feature particularly reduces the, otherwise often observed, fluorescence quenching in dye aggregates. Thus, bright luminescent cyclic and polymeric supramolecular architectures have become available from these dyes by hydrogen-bond and metal-ion directed self-assembly. In those cases where additional π-π-stacking interactions come into play, luminescent organogels and liquid crystals are obtained.}, author = {Würthner, Frank}, journal = {The Scientific Journal of IUPAC}, keywords = {myown}, number = 78, pages = {2341–2350}, title = {Bay-substituted perylene bisimides: Twisted fluorophores for supramolecular chemistry}, volume = {Pure Appl. Chem.}, year = 2009 }

  %0 Journal Article %1 wrthner2009baysubstituted %A Würthner, Frank %D 2009 %J The Scientific Journal of IUPAC %N 78 %P 2341–2350 %R 10.1351/pac200678122341 %T Bay-substituted perylene bisimides: Twisted fluorophores for supramolecular chemistry %U https://doi.org/10.1351/pac200678122341 %V Pure Appl. Chem. %X Perylene bisimides bearing four aryloxy substituents in the 1,6,7,12 positions (so-called bay area) and two receptor units at the imide nitrogens are most useful fluorescent building blocks for the realization of a broad variety of supramolecular architectures. As discussed in this review, this versatility is not only due to the outstanding fluorescence properties of these dyes with quantum yields close to unity, but also a consequence of pronounced twisting of the π-system with an inversion barrier of around 60 kJ/mol (leading to atropisomerism) and conformational flexibility of aryloxy units. The latter two properties endow these dyes with high solubility even in least polar aliphatic solvents and enable the dyes to maintain a distance of >4 Å in their supramolecular assemblies. This feature particularly reduces the, otherwise often observed, fluorescence quenching in dye aggregates. Thus, bright luminescent cyclic and polymeric supramolecular architectures have become available from these dyes by hydrogen-bond and metal-ion directed self-assembly. In those cases where additional π-π-stacking interactions come into play, luminescent organogels and liquid crystals are obtained.
• Photoblinking dynamics in single calix[4]arene-linked perylene bisimide dimers. Ernst, Dominique; Hildner, Richard; Hippius, Catharina; Würthner, Frank; Köhler, Jürgen. In Chemical Physics Letters, 482(1), pp. 93–98. 2009.
  • [ Abstract ]
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  Abstract We have studied the fluorescence from individual bridge-linked perylene bisimide dimers and observed blinking over three decades in time which reveals a power-law distribution for the ‘off’ times. The time traces featured three distinct levels of intensity which we assign to the dimer, monomer and background level, respectively. Based on the chronological order of the occurence of the intensity levels we grouped the time traces into three categories and come to the conclusion that for one of these groups the blinking behaviour is governed by a mechanism that is reminiscent to Coulomb blockade in semiconductor quantum dots.

  @article{ERNST200993, abstract = {Abstract We have studied the fluorescence from individual bridge-linked perylene bisimide dimers and observed blinking over three decades in time which reveals a power-law distribution for the ‘off’ times. The time traces featured three distinct levels of intensity which we assign to the dimer, monomer and background level, respectively. Based on the chronological order of the occurence of the intensity levels we grouped the time traces into three categories and come to the conclusion that for one of these groups the blinking behaviour is governed by a mechanism that is reminiscent to Coulomb blockade in semiconductor quantum dots.}, author = {Ernst, Dominique and Hildner, Richard and Hippius, Catharina and Würthner, Frank and Köhler, Jürgen}, journal = {Chemical Physics Letters}, keywords = {myown}, number = 1, pages = {93 - 98}, title = {Photoblinking dynamics in single calix[4]arene-linked perylene bisimide dimers}, volume = 482, year = 2009 }

  %0 Journal Article %1 ERNST200993 %A Ernst, Dominique %A Hildner, Richard %A Hippius, Catharina %A Würthner, Frank %A Köhler, Jürgen %D 2009 %J Chemical Physics Letters %N 1 %P 93 - 98 %R https://doi.org/10.1016/j.cplett.2009.09.096 %T Photoblinking dynamics in single calix[4]arene-linked perylene bisimide dimers %U http://www.sciencedirect.com/science/article/pii/S0009261409012172 %V 482 %X Abstract We have studied the fluorescence from individual bridge-linked perylene bisimide dimers and observed blinking over three decades in time which reveals a power-law distribution for the ‘off’ times. The time traces featured three distinct levels of intensity which we assign to the dimer, monomer and background level, respectively. Based on the chronological order of the occurence of the intensity levels we grouped the time traces into three categories and come to the conclusion that for one of these groups the blinking behaviour is governed by a mechanism that is reminiscent to Coulomb blockade in semiconductor quantum dots.
• Temperature-Dependent Exciton Dynamics in J-Aggregates—When Disorder Plays a Role. Kaiser, Theo E.; Scheblykin, Ivan G.; Thomsson, Daniel; Würthner, Frank. In The Journal of Physical Chemistry B, 113(48), pp. 15836–15842. 2009.

  PMID: 19754082
  • [ Abstract ]
  • [ BibTeX ]
  • [ EndNote ]
  • [ DOI ]
  Absorption and fluorescence spectral properties of J-aggregates of core-tetrasubstituted perylene bisimide (PBI) dyes have been investigated in the temperature range from 300 to 5 K. A special feature of the present PBI J-aggregates is that, in contrast to classical J-aggregates like that of pseudoisocyanine (PIC), the chromophores are held together not only by van-der-Waals interactions but also by hydrogen bonds. The temperature dependence of the spectral band widths and the Stokes shift for PBI 1 aggregates are compared with those for 3,3′-bis-(3-sulfopropyl)-5,5′-dichloro-9-ethylthiacarbocyanine (THIATS) J-aggregates, which have been studied in detail previously (J. Phys. Chem. B 2001, 105, 4636−4646). The assemblies of PBI 1 possess very broad absorption bands compared to those of THIATS, even at low temperature (5 times broader). We interpret this observation as an indication for a very large level of disorder in the case of PBI 1 assemblies. Possible sources of disorder in aggregates of PBI 1 are discussed. Despite large quantitative differences, both aggregates show qualitatively the same temperature dependence of the Stokes shift calculated in units of fluorescence bandwidth. The observed temperature dependences are discussed in terms of exciton thermal population of different states of disordered aggregates. Unexpectedly low thermal activation energy of exciton migration is observed for PBI 1 aggregates.

  @article{doi:10.1021/jp905246r, abstract = {Absorption and fluorescence spectral properties of J-aggregates of core-tetrasubstituted perylene bisimide (PBI) dyes have been investigated in the temperature range from 300 to 5 K. A special feature of the present PBI J-aggregates is that, in contrast to classical J-aggregates like that of pseudoisocyanine (PIC), the chromophores are held together not only by van-der-Waals interactions but also by hydrogen bonds. The temperature dependence of the spectral band widths and the Stokes shift for PBI 1 aggregates are compared with those for 3,3′-bis-(3-sulfopropyl)-5,5′-dichloro-9-ethylthiacarbocyanine (THIATS) J-aggregates, which have been studied in detail previously (J. Phys. Chem. B 2001, 105, 4636−4646). The assemblies of PBI 1 possess very broad absorption bands compared to those of THIATS, even at low temperature (5 times broader). We interpret this observation as an indication for a very large level of disorder in the case of PBI 1 assemblies. Possible sources of disorder in aggregates of PBI 1 are discussed. Despite large quantitative differences, both aggregates show qualitatively the same temperature dependence of the Stokes shift calculated in units of fluorescence bandwidth. The observed temperature dependences are discussed in terms of exciton thermal population of different states of disordered aggregates. Unexpectedly low thermal activation energy of exciton migration is observed for PBI 1 aggregates.}, author = {Kaiser, Theo E. and Scheblykin, Ivan G. and Thomsson, Daniel and Würthner, Frank}, journal = {The Journal of Physical Chemistry B}, keywords = {myown}, note = {PMID: 19754082}, number = 48, pages = {15836-15842}, title = {Temperature-Dependent Exciton Dynamics in J-Aggregates—When Disorder Plays a Role}, volume = 113, year = 2009 }

  %0 Journal Article %1 doi:10.1021/jp905246r %A Kaiser, Theo E. %A Scheblykin, Ivan G. %A Thomsson, Daniel %A Würthner, Frank %D 2009 %J The Journal of Physical Chemistry B %N 48 %P 15836-15842 %R 10.1021/jp905246r %T Temperature-Dependent Exciton Dynamics in J-Aggregates—When Disorder Plays a Role %U http://dx.doi.org/10.1021/jp905246r %V 113 %X Absorption and fluorescence spectral properties of J-aggregates of core-tetrasubstituted perylene bisimide (PBI) dyes have been investigated in the temperature range from 300 to 5 K. A special feature of the present PBI J-aggregates is that, in contrast to classical J-aggregates like that of pseudoisocyanine (PIC), the chromophores are held together not only by van-der-Waals interactions but also by hydrogen bonds. The temperature dependence of the spectral band widths and the Stokes shift for PBI 1 aggregates are compared with those for 3,3′-bis-(3-sulfopropyl)-5,5′-dichloro-9-ethylthiacarbocyanine (THIATS) J-aggregates, which have been studied in detail previously (J. Phys. Chem. B 2001, 105, 4636−4646). The assemblies of PBI 1 possess very broad absorption bands compared to those of THIATS, even at low temperature (5 times broader). We interpret this observation as an indication for a very large level of disorder in the case of PBI 1 assemblies. Possible sources of disorder in aggregates of PBI 1 are discussed. Despite large quantitative differences, both aggregates show qualitatively the same temperature dependence of the Stokes shift calculated in units of fluorescence bandwidth. The observed temperature dependences are discussed in terms of exciton thermal population of different states of disordered aggregates. Unexpectedly low thermal activation energy of exciton migration is observed for PBI 1 aggregates.
• High-Performance Air-Stable n-Channel Organic Thin Film Transistors Based on Halogenated Perylene Bisimide Semiconductors. Schmidt, Rüdiger; Oh, Joon Hak; Sun, Ya-Sen; Deppisch, Manuela; Krause, Ana-Maria; Radacki, Krzysztof; Braunschweig, Holger; Könemann, Martin; Erk, Peter; Bao, Zhenan; Würthner, Frank. In J. Am. Chem. Soc., 131(17), pp. 6215–6228. 2009.

  PMID: 19354212
  • [ Abstract ]
  • [ BibTeX ]
  • [ EndNote ]
  • [ DOI ]
  The syntheses and comprehensive characterization of 14 organic semiconductors based on perylene bisimide (PBI) dyes that are equipped with up to four halogen substituents in the bay area of the perylene core and five different highly fluorinated imide substituents are described. The influence of the substituents on the LUMO level and the solid state packing of PBIs was examined by cyclic voltammetry and single crystal structure analyses of seven PBI derivatives, respectively. Top-contact/bottom-gate organic thin film transistor (OTFT) devices were constructed by vacuum deposition of these PBIs on SiO2 gate dielectrics that had been pretreated with n-octadecyl triethoxysilane in vapor phase (OTS-V) or solution phase (OTS-S). The electrical characterization of all devices was accomplished in a nitrogen atmosphere as well as in air, and the structural features of thin films were explored by grazing incidence X-ray diffraction (GIXD) and atomic force microscopy (AFM). Several of those PBIs that bear only hydrogen or up to two fluorine substitutents at the concomitantly flat PBI core afforded excellent n-channel transistors, in particular, on OTS-S substrate and even in air (μ > 0.5 cm2 V−1 s−1; Ion/Ioff > 106). The best OTFTs were obtained for 2,2,3,3,4,4,4-heptafluorobutyl-substituted PBI 1a (“PTCDI-C4F7”) on OTS-S with n-channel field effect mobilities consistently >1 cm2 V−1 s−1 and on-to-off current rations of 106 in a nitrogen atmosphere and in air. For distorted core-tetrahalogenated (fluorine, chlorine, or bromine) PBIs, less advantageous solid state packing properties were found and high performance OTFTs were obtained from only one tetrachlorinated derivative (2d on OTS-S). The excellent on-to-off current modulation combined with high mobility in air makes these PBIs suitable for a wide range of practical applications.

  @article{doi:10.1021/ja901077a, abstract = {The syntheses and comprehensive characterization of 14 organic semiconductors based on perylene bisimide (PBI) dyes that are equipped with up to four halogen substituents in the bay area of the perylene core and five different highly fluorinated imide substituents are described. The influence of the substituents on the LUMO level and the solid state packing of PBIs was examined by cyclic voltammetry and single crystal structure analyses of seven PBI derivatives, respectively. Top-contact/bottom-gate organic thin film transistor (OTFT) devices were constructed by vacuum deposition of these PBIs on SiO2 gate dielectrics that had been pretreated with n-octadecyl triethoxysilane in vapor phase (OTS-V) or solution phase (OTS-S). The electrical characterization of all devices was accomplished in a nitrogen atmosphere as well as in air, and the structural features of thin films were explored by grazing incidence X-ray diffraction (GIXD) and atomic force microscopy (AFM). Several of those PBIs that bear only hydrogen or up to two fluorine substitutents at the concomitantly flat PBI core afforded excellent n-channel transistors, in particular, on OTS-S substrate and even in air (μ > 0.5 cm2 V−1 s−1; Ion/Ioff > 106). The best OTFTs were obtained for 2,2,3,3,4,4,4-heptafluorobutyl-substituted PBI 1a (“PTCDI-C4F7”) on OTS-S with n-channel field effect mobilities consistently >1 cm2 V−1 s−1 and on-to-off current rations of 106 in a nitrogen atmosphere and in air. For distorted core-tetrahalogenated (fluorine, chlorine, or bromine) PBIs, less advantageous solid state packing properties were found and high performance OTFTs were obtained from only one tetrachlorinated derivative (2d on OTS-S). The excellent on-to-off current modulation combined with high mobility in air makes these PBIs suitable for a wide range of practical applications.}, author = {Schmidt, Rüdiger and Oh, Joon Hak and Sun, Ya-Sen and Deppisch, Manuela and Krause, Ana-Maria and Radacki, Krzysztof and Braunschweig, Holger and Könemann, Martin and Erk, Peter and Bao, Zhenan and Würthner, Frank}, journal = {J. Am. Chem. Soc.}, keywords = {myown}, note = {PMID: 19354212}, number = 17, pages = {6215-6228}, title = {High-Performance Air-Stable n-Channel Organic Thin Film Transistors Based on Halogenated Perylene Bisimide Semiconductors}, volume = 131, year = 2009 }

  %0 Journal Article %1 doi:10.1021/ja901077a %A Schmidt, Rüdiger %A Oh, Joon Hak %A Sun, Ya-Sen %A Deppisch, Manuela %A Krause, Ana-Maria %A Radacki, Krzysztof %A Braunschweig, Holger %A Könemann, Martin %A Erk, Peter %A Bao, Zhenan %A Würthner, Frank %D 2009 %J J. Am. Chem. Soc. %N 17 %P 6215-6228 %R 10.1021/ja901077a %T High-Performance Air-Stable n-Channel Organic Thin Film Transistors Based on Halogenated Perylene Bisimide Semiconductors %U http://dx.doi.org/10.1021/ja901077a %V 131 %X The syntheses and comprehensive characterization of 14 organic semiconductors based on perylene bisimide (PBI) dyes that are equipped with up to four halogen substituents in the bay area of the perylene core and five different highly fluorinated imide substituents are described. The influence of the substituents on the LUMO level and the solid state packing of PBIs was examined by cyclic voltammetry and single crystal structure analyses of seven PBI derivatives, respectively. Top-contact/bottom-gate organic thin film transistor (OTFT) devices were constructed by vacuum deposition of these PBIs on SiO2 gate dielectrics that had been pretreated with n-octadecyl triethoxysilane in vapor phase (OTS-V) or solution phase (OTS-S). The electrical characterization of all devices was accomplished in a nitrogen atmosphere as well as in air, and the structural features of thin films were explored by grazing incidence X-ray diffraction (GIXD) and atomic force microscopy (AFM). Several of those PBIs that bear only hydrogen or up to two fluorine substitutents at the concomitantly flat PBI core afforded excellent n-channel transistors, in particular, on OTS-S substrate and even in air (μ > 0.5 cm2 V−1 s−1; Ion/Ioff > 106). The best OTFTs were obtained for 2,2,3,3,4,4,4-heptafluorobutyl-substituted PBI 1a (“PTCDI-C4F7”) on OTS-S with n-channel field effect mobilities consistently >1 cm2 V−1 s−1 and on-to-off current rations of 106 in a nitrogen atmosphere and in air. For distorted core-tetrahalogenated (fluorine, chlorine, or bromine) PBIs, less advantageous solid state packing properties were found and high performance OTFTs were obtained from only one tetrachlorinated derivative (2d on OTS-S). The excellent on-to-off current modulation combined with high mobility in air makes these PBIs suitable for a wide range of practical applications.
• Fluorescent J-Aggregates of Core-Substituted Perylene Bisimides: Studies on Structure−Property Relationship, Nucleation−Elongation Mechanism, and Sergeants-and-Soldiers Principle. Kaiser, Theo E.; Stepanenko, Vladimir; Würthner, Frank. In J. Am. Chem. Soc., 131(19), pp. 6719–6732. 2009.

  PMID: 19388696
  • [ Abstract ]
  • [ BibTeX ]
  • [ EndNote ]
  • [ DOI ]
  A series of highly soluble and fluorescent, at core tetraaryloxy-substituted and in imide positions hydrogen atom containing perylene bisimide (PBI) dyes 1a−e with varying peripheral side chains have been synthesized and thoroughly characterized. The self-assembly of these PBIs has been studied in detail by UV/vis, linear dichroism (LD) and circular dichroism (CD) spectroscopy, and scanning probe microscopy (AFM, STM). These studies revealed that the present PBIs self-assemble into extended double string cables, which consist of two hydrogen-bonded supramolecular polymeric chains of densely packed and strongly excitonically coupled PBI chromophores, providing highly fluorescent J-aggregates. The aggregation strength (“melting” temperature) and the fluorescence properties of these J-aggregates are dependent on the number and chain length of the peripheral alkoxy substituents, thus revealing a structure−property relationship. In contrast to previously reported assemblies of PBIs, for which the aggregation process is described by the isodesmic (or equal K) model, a cooperative nucleation−elongation mechanism applies for the aggregation of the present assemblies as revealed by concentration-dependent UV/vis absorption studies with the chiral PBI 1e, providing equilibrium constants for dimerization (= nucleation) of K2 = 13 ± 11 L mol−1 and for elongation of K = 2.3 ± 0.1 × 106 L mol−1 in methylcyclohexane (MCH). LD spectroscopic measurements have been performed to analyze the orientation of the monomers within the aggregates. The nonlinearity of chiral amplification in PBI aggregates directed by sergeants-and-soldiers principle has been elucidated by coaggregation experiments of different PBI dyes using CD spectroscopy. The dimensions as well as the molecular arrangement of the monomeric units in assemblies have been explored by atomic force microscopy (AFM) and scanning tunneling microscopy (STM).

  @article{doi:10.1021/ja900684h, abstract = {A series of highly soluble and fluorescent, at core tetraaryloxy-substituted and in imide positions hydrogen atom containing perylene bisimide (PBI) dyes 1a−e with varying peripheral side chains have been synthesized and thoroughly characterized. The self-assembly of these PBIs has been studied in detail by UV/vis, linear dichroism (LD) and circular dichroism (CD) spectroscopy, and scanning probe microscopy (AFM, STM). These studies revealed that the present PBIs self-assemble into extended double string cables, which consist of two hydrogen-bonded supramolecular polymeric chains of densely packed and strongly excitonically coupled PBI chromophores, providing highly fluorescent J-aggregates. The aggregation strength (“melting” temperature) and the fluorescence properties of these J-aggregates are dependent on the number and chain length of the peripheral alkoxy substituents, thus revealing a structure−property relationship. In contrast to previously reported assemblies of PBIs, for which the aggregation process is described by the isodesmic (or equal K) model, a cooperative nucleation−elongation mechanism applies for the aggregation of the present assemblies as revealed by concentration-dependent UV/vis absorption studies with the chiral PBI 1e, providing equilibrium constants for dimerization (= nucleation) of K2 = 13 ± 11 L mol−1 and for elongation of K = 2.3 ± 0.1 × 106 L mol−1 in methylcyclohexane (MCH). LD spectroscopic measurements have been performed to analyze the orientation of the monomers within the aggregates. The nonlinearity of chiral amplification in PBI aggregates directed by sergeants-and-soldiers principle has been elucidated by coaggregation experiments of different PBI dyes using CD spectroscopy. The dimensions as well as the molecular arrangement of the monomeric units in assemblies have been explored by atomic force microscopy (AFM) and scanning tunneling microscopy (STM).}, author = {Kaiser, Theo E. and Stepanenko, Vladimir and Würthner, Frank}, journal = {J. Am. Chem. Soc.}, keywords = {myown}, note = {PMID: 19388696}, number = 19, pages = {6719-6732}, title = {Fluorescent J-Aggregates of Core-Substituted Perylene Bisimides: Studies on Structure−Property Relationship, Nucleation−Elongation Mechanism, and Sergeants-and-Soldiers Principle}, volume = 131, year = 2009 }

  %0 Journal Article %1 doi:10.1021/ja900684h %A Kaiser, Theo E. %A Stepanenko, Vladimir %A Würthner, Frank %D 2009 %J J. Am. Chem. Soc. %N 19 %P 6719-6732 %R 10.1021/ja900684h %T Fluorescent J-Aggregates of Core-Substituted Perylene Bisimides: Studies on Structure−Property Relationship, Nucleation−Elongation Mechanism, and Sergeants-and-Soldiers Principle %U http://dx.doi.org/10.1021/ja900684h %V 131 %X A series of highly soluble and fluorescent, at core tetraaryloxy-substituted and in imide positions hydrogen atom containing perylene bisimide (PBI) dyes 1a−e with varying peripheral side chains have been synthesized and thoroughly characterized. The self-assembly of these PBIs has been studied in detail by UV/vis, linear dichroism (LD) and circular dichroism (CD) spectroscopy, and scanning probe microscopy (AFM, STM). These studies revealed that the present PBIs self-assemble into extended double string cables, which consist of two hydrogen-bonded supramolecular polymeric chains of densely packed and strongly excitonically coupled PBI chromophores, providing highly fluorescent J-aggregates. The aggregation strength (“melting” temperature) and the fluorescence properties of these J-aggregates are dependent on the number and chain length of the peripheral alkoxy substituents, thus revealing a structure−property relationship. In contrast to previously reported assemblies of PBIs, for which the aggregation process is described by the isodesmic (or equal K) model, a cooperative nucleation−elongation mechanism applies for the aggregation of the present assemblies as revealed by concentration-dependent UV/vis absorption studies with the chiral PBI 1e, providing equilibrium constants for dimerization (= nucleation) of K2 = 13 ± 11 L mol−1 and for elongation of K = 2.3 ± 0.1 × 106 L mol−1 in methylcyclohexane (MCH). LD spectroscopic measurements have been performed to analyze the orientation of the monomers within the aggregates. The nonlinearity of chiral amplification in PBI aggregates directed by sergeants-and-soldiers principle has been elucidated by coaggregation experiments of different PBI dyes using CD spectroscopy. The dimensions as well as the molecular arrangement of the monomeric units in assemblies have been explored by atomic force microscopy (AFM) and scanning tunneling microscopy (STM).
• Trimeric Cyclic Assemblies of Calix[4]arene-Tethered Bismerocyanines. Lohr, Andreas; Uemura, Shinobu; Würthner, Frank. In Angew. Chem. Int. Ed., 48(33), pp. 6165–6168. 2009.
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  @article{ANIE:ANIE200902299, author = {Lohr, Andreas and Uemura, Shinobu and Würthner, Frank}, journal = {Angew. Chem. Int. Ed.}, keywords = {myown}, number = 33, pages = {6165–6168}, publisher = {WILEY-VCH Verlag}, title = {Trimeric Cyclic Assemblies of Calix[4]arene-Tethered Bismerocyanines}, volume = 48, year = 2009 }

  %0 Journal Article %1 ANIE:ANIE200902299 %A Lohr, Andreas %A Uemura, Shinobu %A Würthner, Frank %D 2009 %I WILEY-VCH Verlag %J Angew. Chem. Int. Ed. %N 33 %P 6165--6168 %R 10.1002/anie.200902299 %T Trimeric Cyclic Assemblies of Calix[4]arene-Tethered Bismerocyanines %U http://dx.doi.org/10.1002/anie.200902299 %V 48
• Step-wise self-assembly of a small molecule with two orthogonal binding interactions leads to single stranded linear polymers in DMSO. Groger, Gerd; Stepanenko, Vladimir; Würthner, Frank; Schmuck, Carsten. In Chem. Commun., (6), pp. 698–700. 2009.
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  The step-wise self-assembly of a small, self-complementary monomer with two orthogonal binding interactions, ion pairing and metal-ligand binding, is described; zwitterion 1 forms ion paired dimers in DMSO which, upon addition of 0.5 equivalents of Fe(ii), aggregate into single stranded linear polymers.

  @article{B820281H, abstract = {The step-wise self-assembly of a small{,} self-complementary monomer with two orthogonal binding interactions{,} ion pairing and metal-ligand binding{,} is described; zwitterion 1 forms ion paired dimers in DMSO which{,} upon addition of 0.5 equivalents of Fe(ii){,} aggregate into single stranded linear polymers.}, author = {Groger, Gerd and Stepanenko, Vladimir and Würthner, Frank and Schmuck, Carsten}, journal = {Chem. Commun.}, keywords = {myown}, number = 6, pages = {698-700}, publisher = {The Royal Society of Chemistry}, title = {Step-wise self-assembly of a small molecule with two orthogonal binding interactions leads to single stranded linear polymers in DMSO}, year = 2009 }

  %0 Journal Article %1 B820281H %A Groger, Gerd %A Stepanenko, Vladimir %A Würthner, Frank %A Schmuck, Carsten %D 2009 %I The Royal Society of Chemistry %J Chem. Commun. %N 6 %P 698-700 %R 10.1039/B820281H %T Step-wise self-assembly of a small molecule with two orthogonal binding interactions leads to single stranded linear polymers in DMSO %U http://dx.doi.org/10.1039/B820281H %X The step-wise self-assembly of a small, self-complementary monomer with two orthogonal binding interactions, ion pairing and metal-ligand binding, is described; zwitterion 1 forms ion paired dimers in DMSO which, upon addition of 0.5 equivalents of Fe(ii), aggregate into single stranded linear polymers.
• Self-assembled [small pi]-stacks of functional dyes in solution: structural and thermodynamic features. Chen, Zhijian; Lohr, Andreas; Saha-Moller, Chantu R.; Würthner, Frank. In Chem. Soc. Rev., 38(2), pp. 564–584. 2009.
  • [ Abstract ]
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  This critical review provides an overview on the formation of [small pi]-stacks of functional dyes in solution, aiming to acquaint young researchers with this topical research field and to stimulate further advance in supramolecular dye chemistry. Different mathematical models that have been proposed and applied for the description of aggregation equilibria of [small pi]-systems in solution are discussed. The factors that have significant impact on the structural features of aggregates and the thermodynamics of [small pi]-[small pi] stacking such as electrostatic interactions, size and geometry of the dye molecules are covered in this review. A comparison of the binding strength is made for different classes of functional [small pi]-conjugated systems, from simple benzene to more extended polycyclic hydrocarbon molecules, including triphenylenes and hexabenzocoronenes, heteroaromatic porphyrins and phthalocyanines, quadrupolar naphthalene and perylene bisimides, dipolar or even zwitterionic merocyanines and squaraines, and some macrocyclic dyes. Solvent effects on binding constants are analysed by linear free energy relationships with various solvent polarity scales (98 references with multiple entries).

  @article{B809359H, abstract = {This critical review provides an overview on the formation of [small pi]-stacks of functional dyes in solution{,} aiming to acquaint young researchers with this topical research field and to stimulate further advance in supramolecular dye chemistry. Different mathematical models that have been proposed and applied for the description of aggregation equilibria of [small pi]-systems in solution are discussed. The factors that have significant impact on the structural features of aggregates and the thermodynamics of [small pi]-[small pi] stacking such as electrostatic interactions{,} size and geometry of the dye molecules are covered in this review. A comparison of the binding strength is made for different classes of functional [small pi]-conjugated systems{,} from simple benzene to more extended polycyclic hydrocarbon molecules{,} including triphenylenes and hexabenzocoronenes{,} heteroaromatic porphyrins and phthalocyanines{,} quadrupolar naphthalene and perylene bisimides{,} dipolar or even zwitterionic merocyanines and squaraines{,} and some macrocyclic dyes. Solvent effects on binding constants are analysed by linear free energy relationships with various solvent polarity scales (98 references with multiple entries).}, author = {Chen, Zhijian and Lohr, Andreas and Saha-Moller, Chantu R. and Würthner, Frank}, journal = {Chem. Soc. Rev.}, keywords = {myown}, number = 2, pages = {564-584}, publisher = {The Royal Society of Chemistry}, title = {Self-assembled [small pi]-stacks of functional dyes in solution: structural and thermodynamic features}, volume = 38, year = 2009 }

  %0 Journal Article %1 B809359H %A Chen, Zhijian %A Lohr, Andreas %A Saha-Moller, Chantu R. %A Würthner, Frank %D 2009 %I The Royal Society of Chemistry %J Chem. Soc. Rev. %N 2 %P 564-584 %R 10.1039/B809359H %T Self-assembled [small pi]-stacks of functional dyes in solution: structural and thermodynamic features %U http://dx.doi.org/10.1039/B809359H %V 38 %X This critical review provides an overview on the formation of [small pi]-stacks of functional dyes in solution, aiming to acquaint young researchers with this topical research field and to stimulate further advance in supramolecular dye chemistry. Different mathematical models that have been proposed and applied for the description of aggregation equilibria of [small pi]-systems in solution are discussed. The factors that have significant impact on the structural features of aggregates and the thermodynamics of [small pi]-[small pi] stacking such as electrostatic interactions, size and geometry of the dye molecules are covered in this review. A comparison of the binding strength is made for different classes of functional [small pi]-conjugated systems, from simple benzene to more extended polycyclic hydrocarbon molecules, including triphenylenes and hexabenzocoronenes, heteroaromatic porphyrins and phthalocyanines, quadrupolar naphthalene and perylene bisimides, dipolar or even zwitterionic merocyanines and squaraines, and some macrocyclic dyes. Solvent effects on binding constants are analysed by linear free energy relationships with various solvent polarity scales (98 references with multiple entries).
• Supramolecular self-assembled multilayers of terpyridine-functionalized perylene bisimide metal complexes. Tuccitto, N.; Delfanti, I.; Torrisi, V.; Scandola, F.; Chiorboli, C.; Stepanenko, V.; Würthner, Frank; Licciardello, A. In Phys. Chem. Chem. Phys., 11(20), pp. 4033–4038. 2009.
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  A terpyridine-functionalized perylene bisimide chromophore (TPBI) has been used as a building block in the stepwise, layer-by-layer fabrication of self-assembled Fe-TPBI multilayers on gold, with the assembled supramolecular chains oriented approximately perpendicular to the gold surface. Time-resolved spectroscopy measurements seem to indicate that the energy absorbed by the multilayer is promptly dissipated to the gold surface by ultrafast processes.

  @article{B819711N, abstract = {A terpyridine-functionalized perylene bisimide chromophore (TPBI) has been used as a building block in the stepwise, layer-by-layer fabrication of self-assembled Fe-TPBI multilayers on gold, with the assembled supramolecular chains oriented approximately perpendicular to the gold surface. Time-resolved spectroscopy measurements seem to indicate that the energy absorbed by the multilayer is promptly dissipated to the gold surface by ultrafast processes.}, author = {Tuccitto, N. and Delfanti, I. and Torrisi, V. and Scandola, F. and Chiorboli, C. and Stepanenko, V. and Würthner, Frank and Licciardello, A.}, journal = {Phys. Chem. Chem. Phys.}, keywords = {myown}, number = 20, pages = {4033-4038}, publisher = {The Royal Society of Chemistry}, title = {Supramolecular self-assembled multilayers of terpyridine-functionalized perylene bisimide metal complexes}, volume = 11, year = 2009 }

  %0 Journal Article %1 B819711N %A Tuccitto, N. %A Delfanti, I. %A Torrisi, V. %A Scandola, F. %A Chiorboli, C. %A Stepanenko, V. %A Würthner, Frank %A Licciardello, A. %D 2009 %I The Royal Society of Chemistry %J Phys. Chem. Chem. Phys. %N 20 %P 4033-4038 %R 10.1039/B819711N %T Supramolecular self-assembled multilayers of terpyridine-functionalized perylene bisimide metal complexes %U http://dx.doi.org/10.1039/B819711N %V 11 %X A terpyridine-functionalized perylene bisimide chromophore (TPBI) has been used as a building block in the stepwise, layer-by-layer fabrication of self-assembled Fe-TPBI multilayers on gold, with the assembled supramolecular chains oriented approximately perpendicular to the gold surface. Time-resolved spectroscopy measurements seem to indicate that the energy absorbed by the multilayer is promptly dissipated to the gold surface by ultrafast processes.
• Self-assembly of double-decker cages induced by coordination of perylene bisimide with a trimeric Zn porphyrin: study of the electron transfer dynamics between the two photoactive components. Oliva, Ana I.; Ventura, Barbara; Würthner, Frank; Camara-Campos, Amaya; Hunter, Christopher A.; Ballester, Pablo; Flamigni, Lucia. In Dalton Trans., (20), pp. 4023–4037. 2009.
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  We describe the thermodynamic characterization of the assembly process of a covalently connected trimeric Zn porphyrin 1 induced by coordination to a bispyridyl functionalized perylene bisimide 2. The perylene bisimide ligands act as pillars via two axial coordination bonds with the porphyrinic Zn(ii) ions fixing the planes of the porphyrin units in a nearly co-facial orientation and inducing the formation of trigonal prism-like structures. The fully assembled 12[middle dot]23 aggregate and the partially assembled one, 12[middle dot]22, in which only two zinc porphyrin sites of trimeric 1 are axially coordinated to 2, are present in solution in equilibrium with freely diffusing species 1 and 2. The strong quenching observed in the mixture for the luminescence of the components 2 and 1 is ascribed to an efficient photoinduced electron transfer from the Zn porphyrin units of 1 to coordinated 2 occurring upon excitation of both components within the assemblies. In the formed assemblies, the Zn porphyrin units of the trimer 1 behave independently. Thus, the porphyrin units that are not coordinated with 2 in the partially assembled complex, 12[middle dot]22, display the same photophysical behaviour registered for freely diffusing 1. The rate of charge separation within the cage is nearly independent on the polarity of the solvent (ca. 1010 s-1) whereas the charge recombination process, leading to the ground state, has a lifetime of 110 ps in dichloromethane and ca. 6 ns in toluene, in agreement with a Marcus inverted behaviour.

  @article{B819496C, abstract = {We describe the thermodynamic characterization of the assembly process of a covalently connected trimeric Zn porphyrin 1 induced by coordination to a bispyridyl functionalized perylene bisimide 2. The perylene bisimide ligands act as pillars via two axial coordination bonds with the porphyrinic Zn(ii) ions fixing the planes of the porphyrin units in a nearly co-facial orientation and inducing the formation of trigonal prism-like structures. The fully assembled 12[middle dot]23 aggregate and the partially assembled one{,} 12[middle dot]22{,} in which only two zinc porphyrin sites of trimeric 1 are axially coordinated to 2{,} are present in solution in equilibrium with freely diffusing species 1 and 2. The strong quenching observed in the mixture for the luminescence of the components 2 and 1 is ascribed to an efficient photoinduced electron transfer from the Zn porphyrin units of 1 to coordinated 2 occurring upon excitation of both components within the assemblies. In the formed assemblies{,} the Zn porphyrin units of the trimer 1 behave independently. Thus{,} the porphyrin units that are not coordinated with 2 in the partially assembled complex{,} 12[middle dot]22{,} display the same photophysical behaviour registered for freely diffusing 1. The rate of charge separation within the cage is nearly independent on the polarity of the solvent (ca. 1010 s-1) whereas the charge recombination process{,} leading to the ground state{,} has a lifetime of 110 ps in dichloromethane and ca. 6 ns in toluene{,} in agreement with a Marcus inverted behaviour.}, author = {Oliva, Ana I. and Ventura, Barbara and Würthner, Frank and Camara-Campos, Amaya and Hunter, Christopher A. and Ballester, Pablo and Flamigni, Lucia}, journal = {Dalton Trans.}, keywords = {myown}, number = 20, pages = {4023-4037}, publisher = {The Royal Society of Chemistry}, title = {Self-assembly of double-decker cages induced by coordination of perylene bisimide with a trimeric Zn porphyrin: study of the electron transfer dynamics between the two photoactive components}, year = 2009 }

  %0 Journal Article %1 B819496C %A Oliva, Ana I. %A Ventura, Barbara %A Würthner, Frank %A Camara-Campos, Amaya %A Hunter, Christopher A. %A Ballester, Pablo %A Flamigni, Lucia %D 2009 %I The Royal Society of Chemistry %J Dalton Trans. %N 20 %P 4023-4037 %R 10.1039/B819496C %T Self-assembly of double-decker cages induced by coordination of perylene bisimide with a trimeric Zn porphyrin: study of the electron transfer dynamics between the two photoactive components %U http://dx.doi.org/10.1039/B819496C %X We describe the thermodynamic characterization of the assembly process of a covalently connected trimeric Zn porphyrin 1 induced by coordination to a bispyridyl functionalized perylene bisimide 2. The perylene bisimide ligands act as pillars via two axial coordination bonds with the porphyrinic Zn(ii) ions fixing the planes of the porphyrin units in a nearly co-facial orientation and inducing the formation of trigonal prism-like structures. The fully assembled 12[middle dot]23 aggregate and the partially assembled one, 12[middle dot]22, in which only two zinc porphyrin sites of trimeric 1 are axially coordinated to 2, are present in solution in equilibrium with freely diffusing species 1 and 2. The strong quenching observed in the mixture for the luminescence of the components 2 and 1 is ascribed to an efficient photoinduced electron transfer from the Zn porphyrin units of 1 to coordinated 2 occurring upon excitation of both components within the assemblies. In the formed assemblies, the Zn porphyrin units of the trimer 1 behave independently. Thus, the porphyrin units that are not coordinated with 2 in the partially assembled complex, 12[middle dot]22, display the same photophysical behaviour registered for freely diffusing 1. The rate of charge separation within the cage is nearly independent on the polarity of the solvent (ca. 1010 s-1) whereas the charge recombination process, leading to the ground state, has a lifetime of 110 ps in dichloromethane and ca. 6 ns in toluene, in agreement with a Marcus inverted behaviour.
• Cyclic Self-Assembled Structures of Chlorophyll Dyes on HOPG by the Dendron Wedge Effect. Uemura, Shinobu; Sengupta, Sanchita; Würthner, Frank. In Angew. Chem. Int. Ed., 48(42), pp. 7825–7828. 2009.
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  @article{uemura2009cyclic, author = {Uemura, Shinobu and Sengupta, Sanchita and Würthner, Frank}, journal = {Angew. Chem. Int. Ed.}, keywords = {myown}, number = 42, pages = {7825 - 7828}, publisher = {WILEY-VCH Verlag}, title = {Cyclic Self-Assembled Structures of Chlorophyll Dyes on HOPG by the Dendron Wedge Effect}, volume = 48, year = 2009 }

  %0 Journal Article %1 uemura2009cyclic %A Uemura, Shinobu %A Sengupta, Sanchita %A Würthner, Frank %D 2009 %I WILEY-VCH Verlag %J Angew. Chem. Int. Ed. %N 42 %P 7825 - 7828 %R 10.1002/anie.200902801 %T Cyclic Self-Assembled Structures of Chlorophyll Dyes on HOPG by the Dendron Wedge Effect %U https://onlinelibrary.wiley.com/doi/full/10.1002/anie.200902801 %V 48
• Vesicular perylene dye nanocapsules as supramolecular fluorescent pH sensor systems. Zhang, Xin; Rehm, Stefanie; Safont-Sempere, Marina M.; Würthner, Frank. In Nat Chem, 1(8), pp. 623–629. 2009.
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  @article{zhang2009vesicular, author = {Zhang, Xin and Rehm, Stefanie and Safont-Sempere, Marina M. and Würthner, Frank}, journal = {Nat Chem}, keywords = {myown}, month = 11, number = 8, pages = {623–629}, publisher = {Nature Publishing Group}, title = {Vesicular perylene dye nanocapsules as supramolecular fluorescent pH sensor systems}, volume = 1, year = 2009 }

  %0 Journal Article %1 zhang2009vesicular %A Zhang, Xin %A Rehm, Stefanie %A Safont-Sempere, Marina M. %A Würthner, Frank %D 2009 %I Nature Publishing Group %J Nat Chem %N 8 %P 623--629 %T Vesicular perylene dye nanocapsules as supramolecular fluorescent pH sensor systems %U http://dx.doi.org/10.1038/nchem.368 %V 1
• Electronic structure of epitaxial thin films of bay-substituted perylene bisimide dyes. Scholz, Markus; Schmidt, Rüdiger; Krause, Stefan; Schöll, Achim; Reinert, Friedrich; Würthner, Frank. In Applied Physics A, 95(1), pp. 285–290. 2009.
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  We have investigated epitaxial thin films of three air-stable organic n-type semiconducting perylene tetracarboxylic acid bisimides (PBIs) with fluoroalkyl groups in the imide position with a combination of X-ray, UV, and inverse photoelectron spectroscopy. We explore the applicability of film preparation by organic molecular beam deposition (OMBD) under ultra-high vacuum conditions to these compounds. By means of fluorine and chlorine substituents in the bay area a systematic torsion of the $\pi$-conjugated core of these three PBIs is achieved. Accordingly, these molecules offer a model system to analyze the interplay between the molecular conformation, the film structure, and the electronic structure. Our results show that the PBIs can be deposited intact and contamination free by OMBD and relatively smooth films with layer-to-layer growth can be established. Moreover, the valence spectra reveal the effect of the electro-negative bay substituents as well as of the twisting of the perylene core, which leads to energy shifts of the occupied and unoccupied frontier orbitals.

  @article{Scholz2009, abstract = {We have investigated epitaxial thin films of three air-stable organic n-type semiconducting perylene tetracarboxylic acid bisimides (PBIs) with fluoroalkyl groups in the imide position with a combination of X-ray, UV, and inverse photoelectron spectroscopy. We explore the applicability of film preparation by organic molecular beam deposition (OMBD) under ultra-high vacuum conditions to these compounds. By means of fluorine and chlorine substituents in the bay area a systematic torsion of the $\pi$-conjugated core of these three PBIs is achieved. Accordingly, these molecules offer a model system to analyze the interplay between the molecular conformation, the film structure, and the electronic structure. Our results show that the PBIs can be deposited intact and contamination free by OMBD and relatively smooth films with layer-to-layer growth can be established. Moreover, the valence spectra reveal the effect of the electro-negative bay substituents as well as of the twisting of the perylene core, which leads to energy shifts of the occupied and unoccupied frontier orbitals.}, author = {Scholz, Markus and Schmidt, Rüdiger and Krause, Stefan and Schöll, Achim and Reinert, Friedrich and Würthner, Frank}, journal = {Applied Physics A}, keywords = {myown}, month = {04}, number = 1, pages = {285–290}, title = {Electronic structure of epitaxial thin films of bay-substituted perylene bisimide dyes}, volume = 95, year = 2009 }

  %0 Journal Article %1 Scholz2009 %A Scholz, Markus %A Schmidt, Rüdiger %A Krause, Stefan %A Schöll, Achim %A Reinert, Friedrich %A Würthner, Frank %D 2009 %J Applied Physics A %N 1 %P 285--290 %R 10.1007/s00339-008-5013-1 %T Electronic structure of epitaxial thin films of bay-substituted perylene bisimide dyes %U https://doi.org/10.1007/s00339-008-5013-1 %V 95 %X We have investigated epitaxial thin films of three air-stable organic n-type semiconducting perylene tetracarboxylic acid bisimides (PBIs) with fluoroalkyl groups in the imide position with a combination of X-ray, UV, and inverse photoelectron spectroscopy. We explore the applicability of film preparation by organic molecular beam deposition (OMBD) under ultra-high vacuum conditions to these compounds. By means of fluorine and chlorine substituents in the bay area a systematic torsion of the $\pi$-conjugated core of these three PBIs is achieved. Accordingly, these molecules offer a model system to analyze the interplay between the molecular conformation, the film structure, and the electronic structure. Our results show that the PBIs can be deposited intact and contamination free by OMBD and relatively smooth films with layer-to-layer growth can be established. Moreover, the valence spectra reveal the effect of the electro-negative bay substituents as well as of the twisting of the perylene core, which leads to energy shifts of the occupied and unoccupied frontier orbitals.
• 5-Bromo-17-nitro-26,28-prop-2-en­­oxy-25,27-dipropoxycalix[4]arene. Hippius, Catharina; Würthner, Frank; Bolte, Michael. In Acta Crystallographica Section E, 65(3), p. o617. 2009.
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  Mol­ecules of the title compound, C40H42BrNO6, are located on a crystallographic twofold rotation axis. As a result, the nitro group and bromine residue are mutually disordered with equal occupancies. The prop­oxy-substituted aromatic rings are close to parallel to each other [dihedral angle = 21.24 (1)°], whereas the propen­oxy-substituted rings enclose a dihedral angle of 70.44 (1)°. The dihedral angles between the methyl­ene C atoms and the aromatic rings shows that the propen­oxy substituted rings are bent away from the calixarene cavity [dihedral angle between the planes = 35.22 (8)°], whereas the prop­oxy-substituted rings are almost perpendicular [79.38 (10)°] to the plane of the methyl­ene C atoms.

  @article{Hippius:at2726, abstract = {Mol­ecules of the title compound, C40H42BrNO6, are located on a crystallographic twofold rotation axis. As a result, the nitro group and bromine residue are mutually disordered with equal occupancies. The prop­oxy-substituted aromatic rings are close to parallel to each other [dihedral angle = 21.24 (1)°], whereas the propen­oxy-substituted rings enclose a dihedral angle of 70.44 (1)°. The dihedral angles between the methyl­ene C atoms and the aromatic rings shows that the propen­oxy substituted rings are bent away from the calixarene cavity [dihedral angle between the planes = 35.22 (8)°], whereas the prop­oxy-substituted rings are almost perpendicular [79.38 (10)°] to the plane of the methyl­ene C atoms.}, author = {Hippius, Catharina and Würthner, Frank and Bolte, Michael}, journal = {Acta Crystallographica Section E}, keywords = {myown}, month = {03}, number = 3, pages = {o617}, title = {5-Bromo-17-nitro-26,28-prop-2-en­­oxy-25,27-dipropoxycalix[4]arene}, volume = 65, year = 2009 }

  %0 Journal Article %1 Hippius:at2726 %A Hippius, Catharina %A Würthner, Frank %A Bolte, Michael %D 2009 %J Acta Crystallographica Section E %N 3 %P o617 %R 10.1107/S160053680900659X %T 5-Bromo-17-nitro-26,28-prop-2-en­­oxy-25,27-dipropoxycalix[4]arene %U https://doi.org/10.1107/S160053680900659X %V 65 %X Mol­ecules of the title compound, C40H42BrNO6, are located on a crystallographic twofold rotation axis. As a result, the nitro group and bromine residue are mutually disordered with equal occupancies. The prop­oxy-substituted aromatic rings are close to parallel to each other [dihedral angle = 21.24 (1)°], whereas the propen­oxy-substituted rings enclose a dihedral angle of 70.44 (1)°. The dihedral angles between the methyl­ene C atoms and the aromatic rings shows that the propen­oxy substituted rings are bent away from the calixarene cavity [dihedral angle between the planes = 35.22 (8)°], whereas the prop­oxy-substituted rings are almost perpendicular [79.38 (10)°] to the plane of the methyl­ene C atoms.
• Self-Assembly of Semiconductor Organogelator Nanowires for Photoinduced Charge Separation. Wicklein, André; Ghosh, Suhrit; Sommer, Michael; Würthner, Frank; Thelakkat, Mukundan. In ACS Nano, 3(5), pp. 1107–1114. 2009.

  PMID: 19408933
  • [ Abstract ]
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  We investigated an innovative concept of general validity based on an organogel/polymer system to generate donor−acceptor nanostructures suitable for charge generation and charge transport. An electron conducting (acceptor) perylene bisimide organogelator forms nanowires in suitable solvents during gelation process. This phenomenon was utilized for its self-assembly in an amorphous hole conducting (donor) polymer matrix to realize an interpenetrating donor−acceptor interface with inherent morphological stability. The self-assembly and interface generation were carried out either stepwise or in a single-step. Morphology of the donor−acceptor network in thin films obtained via both routes were studied by a combination of scanning electron microscopy and atomic force microscopy. Additionally, photoinduced charge separation and charge transport in these systems were tested in organic solar cells. Fabrication steps of multilayer organogel/polymer photovoltaic devices were optimized with respect to morphology and surface roughness by introducing additional smoothening layers and charge injection/blocking layers. An inverted cell geometry was used here in which electrons are collected at the bottom electrode and holes at the top electrode. The simultaneous preparation of the interface exhibits almost 3-fold improvement in device characteristics compared to the successive method. The device characteristics under AM1.5 spectral conditions and 100 mW/cm2 for the simultaneous preparation route are short circuit current Jsc = 0.28 mAcm−2, open circuit voltage VOC = 390 mV, fill factor FF = 38\%, and a power conversion efficiency η = 0.041\%.

  @article{doi:10.1021/nn9001165, abstract = {We investigated an innovative concept of general validity based on an organogel/polymer system to generate donor−acceptor nanostructures suitable for charge generation and charge transport. An electron conducting (acceptor) perylene bisimide organogelator forms nanowires in suitable solvents during gelation process. This phenomenon was utilized for its self-assembly in an amorphous hole conducting (donor) polymer matrix to realize an interpenetrating donor−acceptor interface with inherent morphological stability. The self-assembly and interface generation were carried out either stepwise or in a single-step. Morphology of the donor−acceptor network in thin films obtained via both routes were studied by a combination of scanning electron microscopy and atomic force microscopy. Additionally, photoinduced charge separation and charge transport in these systems were tested in organic solar cells. Fabrication steps of multilayer organogel/polymer photovoltaic devices were optimized with respect to morphology and surface roughness by introducing additional smoothening layers and charge injection/blocking layers. An inverted cell geometry was used here in which electrons are collected at the bottom electrode and holes at the top electrode. The simultaneous preparation of the interface exhibits almost 3-fold improvement in device characteristics compared to the successive method. The device characteristics under AM1.5 spectral conditions and 100 mW/cm2 for the simultaneous preparation route are short circuit current Jsc = 0.28 mAcm−2, open circuit voltage VOC = 390 mV, fill factor FF = 38\%, and a power conversion efficiency η = 0.041\%.}, author = {Wicklein, André and Ghosh, Suhrit and Sommer, Michael and Würthner, Frank and Thelakkat, Mukundan}, journal = {ACS Nano}, keywords = {myown}, note = {PMID: 19408933}, number = 5, pages = {1107-1114}, title = {Self-Assembly of Semiconductor Organogelator Nanowires for Photoinduced Charge Separation}, volume = 3, year = 2009 }

  %0 Journal Article %1 doi:10.1021/nn9001165 %A Wicklein, André %A Ghosh, Suhrit %A Sommer, Michael %A Würthner, Frank %A Thelakkat, Mukundan %D 2009 %J ACS Nano %N 5 %P 1107-1114 %R 10.1021/nn9001165 %T Self-Assembly of Semiconductor Organogelator Nanowires for Photoinduced Charge Separation %U http://dx.doi.org/10.1021/nn9001165 %V 3 %X We investigated an innovative concept of general validity based on an organogel/polymer system to generate donor−acceptor nanostructures suitable for charge generation and charge transport. An electron conducting (acceptor) perylene bisimide organogelator forms nanowires in suitable solvents during gelation process. This phenomenon was utilized for its self-assembly in an amorphous hole conducting (donor) polymer matrix to realize an interpenetrating donor−acceptor interface with inherent morphological stability. The self-assembly and interface generation were carried out either stepwise or in a single-step. Morphology of the donor−acceptor network in thin films obtained via both routes were studied by a combination of scanning electron microscopy and atomic force microscopy. Additionally, photoinduced charge separation and charge transport in these systems were tested in organic solar cells. Fabrication steps of multilayer organogel/polymer photovoltaic devices were optimized with respect to morphology and surface roughness by introducing additional smoothening layers and charge injection/blocking layers. An inverted cell geometry was used here in which electrons are collected at the bottom electrode and holes at the top electrode. The simultaneous preparation of the interface exhibits almost 3-fold improvement in device characteristics compared to the successive method. The device characteristics under AM1.5 spectral conditions and 100 mW/cm2 for the simultaneous preparation route are short circuit current Jsc = 0.28 mAcm−2, open circuit voltage VOC = 390 mV, fill factor FF = 38\%, and a power conversion efficiency η = 0.041\%.

• Exciton Trapping in π-Conjugated Materials: A Quantum-Chemistry-Based Protocol Applied to Perylene Bisimide Dye Aggregates. Fink, Reinhold F.; Seibt, Joachim; Engel, Volker; Renz, Manuel; Kaupp, Martin; Lochbrunner, Stefan; Zhao, Hong-Mei; Pfister, Johannes; Würthner, Frank; Engels, Bernd. In J. Am. Chem. Soc., 130(39), pp. 12858–12859. 2008.

  PMID: 18767851
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  Access to excited-state structures and dynamics of π-chromophor aggregates is needed to understand their fluorescence behavior and the properties of related materials. A quantum-chemistry-based protocol that provides quantitative and qualitative insight into fluorescence spectra has been applied to perylene bisimide dimers and provides excellent agreement with measured fluorescence spectra. Both dispersion and dipol−dipole interactions determine the preferred relative arrangements of the chromophores in ground and excited states of the dimer. An exciton trappping mechanism is identified, which may limit the energy transfer properties of perylene bisimide and other dye materials.

  @article{doi:10.1021/ja804331b, abstract = {Access to excited-state structures and dynamics of π-chromophor aggregates is needed to understand their fluorescence behavior and the properties of related materials. A quantum-chemistry-based protocol that provides quantitative and qualitative insight into fluorescence spectra has been applied to perylene bisimide dimers and provides excellent agreement with measured fluorescence spectra. Both dispersion and dipol−dipole interactions determine the preferred relative arrangements of the chromophores in ground and excited states of the dimer. An exciton trappping mechanism is identified, which may limit the energy transfer properties of perylene bisimide and other dye materials.}, author = {Fink, Reinhold F. and Seibt, Joachim and Engel, Volker and Renz, Manuel and Kaupp, Martin and Lochbrunner, Stefan and Zhao, Hong-Mei and Pfister, Johannes and Würthner, Frank and Engels, Bernd}, journal = {J. Am. Chem. Soc.}, keywords = {myown}, note = {PMID: 18767851}, number = 39, pages = {12858-12859}, title = {Exciton Trapping in π-Conjugated Materials: A Quantum-Chemistry-Based Protocol Applied to Perylene Bisimide Dye Aggregates}, volume = 130, year = 2008 }

  %0 Journal Article %1 doi:10.1021/ja804331b %A Fink, Reinhold F. %A Seibt, Joachim %A Engel, Volker %A Renz, Manuel %A Kaupp, Martin %A Lochbrunner, Stefan %A Zhao, Hong-Mei %A Pfister, Johannes %A Würthner, Frank %A Engels, Bernd %D 2008 %J J. Am. Chem. Soc. %N 39 %P 12858-12859 %R 10.1021/ja804331b %T Exciton Trapping in π-Conjugated Materials: A Quantum-Chemistry-Based Protocol Applied to Perylene Bisimide Dye Aggregates %U http://dx.doi.org/10.1021/ja804331b %V 130 %X Access to excited-state structures and dynamics of π-chromophor aggregates is needed to understand their fluorescence behavior and the properties of related materials. A quantum-chemistry-based protocol that provides quantitative and qualitative insight into fluorescence spectra has been applied to perylene bisimide dimers and provides excellent agreement with measured fluorescence spectra. Both dispersion and dipol−dipole interactions determine the preferred relative arrangements of the chromophores in ground and excited states of the dimer. An exciton trappping mechanism is identified, which may limit the energy transfer properties of perylene bisimide and other dye materials.
• Time-dependent amplification of helical bias in self-assembled dye nanorods directed by the sergeants-and-soldiers principle. Lohr, Andreas; Würthner, Frank. In Chem. Commun., (19), pp. 2227–2229. 2008.
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  A pronounced sergeants-and-soldiers directed chiral amplification is observed for the self-assembly of merocyanine dye nanorods and the amplification process is shown to become slower for decreasing fraction of sergeant molecules.

  @article{B802696C, abstract = {A pronounced sergeants-and-soldiers directed chiral amplification is observed for the self-assembly of merocyanine dye nanorods and the amplification process is shown to become slower for decreasing fraction of sergeant molecules.}, author = {Lohr, Andreas and Würthner, Frank}, journal = {Chem. Commun.}, keywords = {myown}, number = 19, pages = {2227-2229}, publisher = {The Royal Society of Chemistry}, title = {Time-dependent amplification of helical bias in self-assembled dye nanorods directed by the sergeants-and-soldiers principle}, year = 2008 }

  %0 Journal Article %1 B802696C %A Lohr, Andreas %A Würthner, Frank %D 2008 %I The Royal Society of Chemistry %J Chem. Commun. %N 19 %P 2227-2229 %R 10.1039/B802696C %T Time-dependent amplification of helical bias in self-assembled dye nanorods directed by the sergeants-and-soldiers principle %U http://dx.doi.org/10.1039/B802696C %X A pronounced sergeants-and-soldiers directed chiral amplification is observed for the self-assembly of merocyanine dye nanorods and the amplification process is shown to become slower for decreasing fraction of sergeant molecules.
• Self-Assembled Zinc Chlorin Rod Antennae Powered by Peripheral Light-Harvesting Chromophores. Röger, Cornelia; Miloslavina, Yuliya; Brunner, Doris; Holzwarth, Alfred R.; Würthner, Frank. In J. Am. Chem. Soc., 130(18), pp. 5929–5939. 2008.
  • [ Abstract ]
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  The multichromophoric dyads 1, 2 and triad 3 have been synthesized by coupling of the appropriately functionalized chlorin derivative with naphthalene diimide dyes through esterification, and subsequent metalation of the chlorin center with zinc acetate. The self-assembly properties of naphthalene diimide (NDI)-zinc chlorin (ZnChl) dyads 1, 2 and triad 3 have been studied in nonpolar, aprotic solvents by UV–vis, CD, and steady-state emission spectroscopy, revealing formation of rod-like structures by noncovalent interactions of zinc chlorin units, while the appended naphthalene diimide dyes do not aggregate at the periphery of the rod antennae. In all these systems, photoexcitation of the enveloping naphthalene diimides at 540 and 620 nm, respectively, leads to highly efficient energy-transfer processes (FRET; ϕET ≥ 0.99) to the inner zinc chlorin backbone, as explored by time-resolved fluorescence spectroscopy on the picosecond time scale. The efficiencies of zinc chlorin rod aggregates for the harvesting of solar light are markedly increased from 26\% for dyad 2 up to 63\% for triad 3, compared to the LH capacity of the monochromophoric aggregates of model system ZnChl 6a. Thus, with the self-assembled zinc chlorin rod antenna based on triad 3, a highly efficient artificial LH system has been achieved.

  @article{doi:10.1021/ja710253q, abstract = {The multichromophoric dyads 1, 2 and triad 3 have been synthesized by coupling of the appropriately functionalized chlorin derivative with naphthalene diimide dyes through esterification, and subsequent metalation of the chlorin center with zinc acetate. The self-assembly properties of naphthalene diimide (NDI)-zinc chlorin (ZnChl) dyads 1, 2 and triad 3 have been studied in nonpolar, aprotic solvents by UV–vis, CD, and steady-state emission spectroscopy, revealing formation of rod-like structures by noncovalent interactions of zinc chlorin units, while the appended naphthalene diimide dyes do not aggregate at the periphery of the rod antennae. In all these systems, photoexcitation of the enveloping naphthalene diimides at 540 and 620 nm, respectively, leads to highly efficient energy-transfer processes (FRET; ϕET ≥ 0.99) to the inner zinc chlorin backbone, as explored by time-resolved fluorescence spectroscopy on the picosecond time scale. The efficiencies of zinc chlorin rod aggregates for the harvesting of solar light are markedly increased from 26\% for dyad 2 up to 63\% for triad 3, compared to the LH capacity of the monochromophoric aggregates of model system ZnChl 6a. Thus, with the self-assembled zinc chlorin rod antenna based on triad 3, a highly efficient artificial LH system has been achieved.}, author = {Röger, Cornelia and Miloslavina, Yuliya and Brunner, Doris and Holzwarth, Alfred R. and Würthner, Frank}, journal = {J. Am. Chem. Soc.}, keywords = {myown}, number = 18, pages = {5929-5939}, title = {Self-Assembled Zinc Chlorin Rod Antennae Powered by Peripheral Light-Harvesting Chromophores}, volume = 130, year = 2008 }

  %0 Journal Article %1 doi:10.1021/ja710253q %A Röger, Cornelia %A Miloslavina, Yuliya %A Brunner, Doris %A Holzwarth, Alfred R. %A Würthner, Frank %D 2008 %J J. Am. Chem. Soc. %N 18 %P 5929-5939 %R 10.1021/ja710253q %T Self-Assembled Zinc Chlorin Rod Antennae Powered by Peripheral Light-Harvesting Chromophores %U http://dx.doi.org/10.1021/ja710253q %V 130 %X The multichromophoric dyads 1, 2 and triad 3 have been synthesized by coupling of the appropriately functionalized chlorin derivative with naphthalene diimide dyes through esterification, and subsequent metalation of the chlorin center with zinc acetate. The self-assembly properties of naphthalene diimide (NDI)-zinc chlorin (ZnChl) dyads 1, 2 and triad 3 have been studied in nonpolar, aprotic solvents by UV–vis, CD, and steady-state emission spectroscopy, revealing formation of rod-like structures by noncovalent interactions of zinc chlorin units, while the appended naphthalene diimide dyes do not aggregate at the periphery of the rod antennae. In all these systems, photoexcitation of the enveloping naphthalene diimides at 540 and 620 nm, respectively, leads to highly efficient energy-transfer processes (FRET; ϕET ≥ 0.99) to the inner zinc chlorin backbone, as explored by time-resolved fluorescence spectroscopy on the picosecond time scale. The efficiencies of zinc chlorin rod aggregates for the harvesting of solar light are markedly increased from 26\% for dyad 2 up to 63\% for triad 3, compared to the LH capacity of the monochromophoric aggregates of model system ZnChl 6a. Thus, with the self-assembled zinc chlorin rod antenna based on triad 3, a highly efficient artificial LH system has been achieved.
• A Black Perylene Bisimide Super Gelator with an Unexpected J-Type Absorption Band. Würthner, Frank; Bauer, Christoph; Stepanenko, Vladimir; Yagai, Shiki. In Advanced Materials, 20(9), pp. 1695–1698. 2008.
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  @article{ADMA:ADMA200702935, author = {Würthner, Frank and Bauer, Christoph and Stepanenko, Vladimir and Yagai, Shiki}, journal = {Advanced Materials}, keywords = {myown}, number = 9, pages = {1695–1698}, publisher = {WILEY-VCH Verlag}, title = {A Black Perylene Bisimide Super Gelator with an Unexpected J-Type Absorption Band}, volume = 20, year = 2008 }

  %0 Journal Article %1 ADMA:ADMA200702935 %A Würthner, Frank %A Bauer, Christoph %A Stepanenko, Vladimir %A Yagai, Shiki %D 2008 %I WILEY-VCH Verlag %J Advanced Materials %N 9 %P 1695--1698 %R 10.1002/adma.200702935 %T A Black Perylene Bisimide Super Gelator with an Unexpected J-Type Absorption Band %U http://dx.doi.org/10.1002/adma.200702935 %V 20
• Highly Fluorescent Lyotropic Mesophases and Organogels Based on J-Aggregates of Core-Twisted Perylene Bisimide Dyes. Li, Xue-Qing; Zhang, Xin; Ghosh, Suhrit; Würthner, Frank. In Chemistry – A European Journal, 14(27), pp. 8074–8078. 2008.
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  @article{CHEM:CHEM200800915, author = {Li, Xue-Qing and Zhang, Xin and Ghosh, Suhrit and Würthner, Frank}, journal = {Chemistry – A European Journal}, keywords = {myown}, number = 27, pages = {8074–8078}, publisher = {WILEY-VCH Verlag}, title = {Highly Fluorescent Lyotropic Mesophases and Organogels Based on J-Aggregates of Core-Twisted Perylene Bisimide Dyes}, volume = 14, year = 2008 }

  %0 Journal Article %1 CHEM:CHEM200800915 %A Li, Xue-Qing %A Zhang, Xin %A Ghosh, Suhrit %A Würthner, Frank %D 2008 %I WILEY-VCH Verlag %J Chemistry – A European Journal %N 27 %P 8074--8078 %R 10.1002/chem.200800915 %T Highly Fluorescent Lyotropic Mesophases and Organogels Based on J-Aggregates of Core-Twisted Perylene Bisimide Dyes %U http://dx.doi.org/10.1002/chem.200800915 %V 14
• Perylene bisimide J-aggregates with absorption maxima in the NIR. Wang, Hao; Kaiser, Theo E.; Uemura, Shinobu; Würthner, Frank. In Chem. Commun., (10), pp. 1181–1183. 2008.
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  NIR absorbing J-aggregates with biomimetic features of chlorophyll dye assemblies are obtained upon hydrogen-bond directed self-assembly of a green 1,7-diamino-substituted perylene bisimide dye.

  @article{B717407A, abstract = {NIR absorbing J-aggregates with biomimetic features of chlorophyll dye assemblies are obtained upon hydrogen-bond directed self-assembly of a green 1{,}7-diamino-substituted perylene bisimide dye.}, author = {Wang, Hao and Kaiser, Theo E. and Uemura, Shinobu and Würthner, Frank}, journal = {Chem. Commun.}, keywords = {myown}, number = 10, pages = {1181-1183}, publisher = {The Royal Society of Chemistry}, title = {Perylene bisimide J-aggregates with absorption maxima in the NIR}, year = 2008 }

  %0 Journal Article %1 B717407A %A Wang, Hao %A Kaiser, Theo E. %A Uemura, Shinobu %A Würthner, Frank %D 2008 %I The Royal Society of Chemistry %J Chem. Commun. %N 10 %P 1181-1183 %R 10.1039/B717407A %T Perylene bisimide J-aggregates with absorption maxima in the NIR %U http://dx.doi.org/10.1039/B717407A %X NIR absorbing J-aggregates with biomimetic features of chlorophyll dye assemblies are obtained upon hydrogen-bond directed self-assembly of a green 1,7-diamino-substituted perylene bisimide dye.
• Identification of oligo(p-phenylene vinylene)-naphthalene diimide heterocomplexes by scanning tunneling microscopy and spectroscopy at the liquid-solid interface. De Cat, Inge; Roger, Cornelia; Lee, Cameron C.; Hoeben, Freek J. M.; Pouderoijen, Maarten J.; Schenning, Albertus P. H. J.; Würthner, Frank; De Feyter, Steven. In Chem. Commun., (43), pp. 5496–5498. 2008.
  • [ Abstract ]
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  Co-assembly of a melamine derivative covalently equipped with two oligo(p-phenylene vinylene) chromophores and a naphthalene diimide dye results in the formation of heterocomplexes at the liquid-solid interface which was shown using bias dependent imaging and scanning tunneling spectroscopy, despite the disordered nature of the assemblies.

  @article{B811961A, abstract = {Co-assembly of a melamine derivative covalently equipped with two oligo(p-phenylene vinylene) chromophores and a naphthalene diimide dye results in the formation of heterocomplexes at the liquid-solid interface which was shown using bias dependent imaging and scanning tunneling spectroscopy{,} despite the disordered nature of the assemblies.}, author = {De Cat, Inge and Roger, Cornelia and Lee, Cameron C. and Hoeben, Freek J. M. and Pouderoijen, Maarten J. and Schenning, Albertus P. H. J. and Würthner, Frank and De Feyter, Steven}, journal = {Chem. Commun.}, keywords = {myown}, number = 43, pages = {5496-5498}, publisher = {The Royal Society of Chemistry}, title = {Identification of oligo(p-phenylene vinylene)-naphthalene diimide heterocomplexes by scanning tunneling microscopy and spectroscopy at the liquid-solid interface}, year = 2008 }

  %0 Journal Article %1 B811961A %A De Cat, Inge %A Roger, Cornelia %A Lee, Cameron C. %A Hoeben, Freek J. M. %A Pouderoijen, Maarten J. %A Schenning, Albertus P. H. J. %A Würthner, Frank %A De Feyter, Steven %D 2008 %I The Royal Society of Chemistry %J Chem. Commun. %N 43 %P 5496-5498 %R 10.1039/B811961A %T Identification of oligo(p-phenylene vinylene)-naphthalene diimide heterocomplexes by scanning tunneling microscopy and spectroscopy at the liquid-solid interface %U http://dx.doi.org/10.1039/B811961A %X Co-assembly of a melamine derivative covalently equipped with two oligo(p-phenylene vinylene) chromophores and a naphthalene diimide dye results in the formation of heterocomplexes at the liquid-solid interface which was shown using bias dependent imaging and scanning tunneling spectroscopy, despite the disordered nature of the assemblies.
• Electrochemical gate-controlled electron transport of redox-active single perylene bisimide molecular junctions. Li, C; Mishchenko, A; Li, Z; Pobelov, I; Wandlowski, Th; Li, X Q; Würthner, F; Bagrets, A; Evers, F. In Journal of Physics: Condensed Matter, 20(37), p. 374122. 2008.
  • [ Abstract ]
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  We report a scanning tunneling microscopy (STM) experiment in an electrochemical environment which studies a prototype molecular switch. The target molecules were perylene tetracarboxylic acid bisimides modified with pyridine (P-PBI) and methylthiol (T-PBI) linker groups and with bulky tert -butyl-phenoxy substituents in the bay area. At a fixed bias voltage, we can control the transport current through a symmetric molecular wire Au|P-PBI(T-PBI)|Au by variation of the electrochemical 'gate' potential. The current increases by up to two orders of magnitude. The conductances of the P-PBI junctions are typically a factor 3 larger than those of T-PBI. A theoretical analysis explains this effect as a consequence of shifting the lowest unoccupied perylene level (LUMO) in or out of the bias window when tuning the electrochemical gate potential VG. The difference in on/off ratios reflects the variation of hybridization of the LUMO with the electrode states with the anchor groups. I T –E S(T) curves of asymmetric molecular junctions formed between a bare Au STM tip and a T-PBI (P-PBI) modified Au(111) electrode in an aqueous electrolyte exhibit a pronounced maximum in the tunneling current at −0.740, which is close to the formal potential of the surface-confined molecules. The experimental data were explained by a sequential two-step electron transfer process.

  @article{0953-8984-20-37-374122, abstract = {We report a scanning tunneling microscopy (STM) experiment in an electrochemical environment which studies a prototype molecular switch. The target molecules were perylene tetracarboxylic acid bisimides modified with pyridine (P-PBI) and methylthiol (T-PBI) linker groups and with bulky tert -butyl-phenoxy substituents in the bay area. At a fixed bias voltage, we can control the transport current through a symmetric molecular wire Au|P-PBI(T-PBI)|Au by variation of the electrochemical 'gate' potential. The current increases by up to two orders of magnitude. The conductances of the P-PBI junctions are typically a factor 3 larger than those of T-PBI. A theoretical analysis explains this effect as a consequence of shifting the lowest unoccupied perylene level (LUMO) in or out of the bias window when tuning the electrochemical gate potential VG. The difference in on/off ratios reflects the variation of hybridization of the LUMO with the electrode states with the anchor groups. I T –E S(T) curves of asymmetric molecular junctions formed between a bare Au STM tip and a T-PBI (P-PBI) modified Au(111) electrode in an aqueous electrolyte exhibit a pronounced maximum in the tunneling current at −0.740, which is close to the formal potential of the surface-confined molecules. The experimental data were explained by a sequential two-step electron transfer process.}, author = {Li, C and Mishchenko, A and Li, Z and Pobelov, I and Wandlowski, Th and Li, X Q and Würthner, F and Bagrets, A and Evers, F}, journal = {Journal of Physics: Condensed Matter}, keywords = {myown}, number = 37, pages = 374122, title = {Electrochemical gate-controlled electron transport of redox-active single perylene bisimide molecular junctions}, volume = 20, year = 2008 }

  %0 Journal Article %1 0953-8984-20-37-374122 %A Li, C %A Mishchenko, A %A Li, Z %A Pobelov, I %A Wandlowski, Th %A Li, X Q %A Würthner, F %A Bagrets, A %A Evers, F %D 2008 %J Journal of Physics: Condensed Matter %N 37 %P 374122 %T Electrochemical gate-controlled electron transport of redox-active single perylene bisimide molecular junctions %U http://stacks.iop.org/0953-8984/20/i=37/a=374122 %V 20 %X We report a scanning tunneling microscopy (STM) experiment in an electrochemical environment which studies a prototype molecular switch. The target molecules were perylene tetracarboxylic acid bisimides modified with pyridine (P-PBI) and methylthiol (T-PBI) linker groups and with bulky tert -butyl-phenoxy substituents in the bay area. At a fixed bias voltage, we can control the transport current through a symmetric molecular wire Au|P-PBI(T-PBI)|Au by variation of the electrochemical 'gate' potential. The current increases by up to two orders of magnitude. The conductances of the P-PBI junctions are typically a factor 3 larger than those of T-PBI. A theoretical analysis explains this effect as a consequence of shifting the lowest unoccupied perylene level (LUMO) in or out of the bias window when tuning the electrochemical gate potential VG. The difference in on/off ratios reflects the variation of hybridization of the LUMO with the electrode states with the anchor groups. I T –E S(T) curves of asymmetric molecular junctions formed between a bare Au STM tip and a T-PBI (P-PBI) modified Au(111) electrode in an aqueous electrolyte exhibit a pronounced maximum in the tunneling current at −0.740, which is close to the formal potential of the surface-confined molecules. The experimental data were explained by a sequential two-step electron transfer process.
• Visualization of Various Supramolecular Assemblies of Oligo(para-phenylenevinylene)–Melamine and Perylene Bisimide. Hoeben, Freek J. M.; Zhang, Jian; Lee, Cameron C.; Pouderoijen, Maarten J.; Wolffs, Martin; Würthner, Frank; Schenning, Albertus P. H. J.; Meijer, E. W.; De Feyter, Steven. In Chemistry – A European Journal, 14(28), pp. 8579–8589. 2008.
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  A melamine derivative has been covalently equipped with two oligo(para-phenylenevinylene) (OPV) chromophores. This procedure yields a bifunctional molecule with two hydrogen-bonding arrays available for complementary binding to perylene bisimide derivatives. Depending on the solvent, hydrogen-bonded trimers, tetramers, and dimers on a graphite surface are observed for pure OPV–melamine by using scanning tunneling microscopy (STM). Upon the addition of perylene bisimide, linear tapes of perylene bisimide, 12-membered rosettes that consist of alternating hydrogen-bonded OPV–melamine and perylene bisimide moieties are visualized. These results provide direct evidence for the possible modes of hydrogen bonding within a supramolecular co-assembly in solution. Subsequently, the optical properties of pure OPV–melamine and co-assemblies with a perylene bisimide derivative were characterized in solution. In an apolar solvent, OPV–melamine self-assembles into chiral superstructures. Disassembly into molecularly dissolved species is reversibly controlled by concentration and temperature. Complementary hydrogen bonding to a perylene bisimide derivative in an apolar solvent yields multicomponent, π-stacked dye assemblies of enhanced stability that are characterized by fluorescence quenching of the constituent chromophores. Titration experiments reveal that a mixture of hydrogen-bonded oligomers is present in solution, rather than a single discrete assembly. The solution experiments are consistent with the STM results, which revealed various supramolecular assemblies. Our system is likely not to be optimally programmed to obtain a discrete co-assembled structure in quantitative yield.

  @article{CHEM:CHEM200800760, abstract = {A melamine derivative has been covalently equipped with two oligo(para-phenylenevinylene) (OPV) chromophores. This procedure yields a bifunctional molecule with two hydrogen-bonding arrays available for complementary binding to perylene bisimide derivatives. Depending on the solvent, hydrogen-bonded trimers, tetramers, and dimers on a graphite surface are observed for pure OPV–melamine by using scanning tunneling microscopy (STM). Upon the addition of perylene bisimide, linear tapes of perylene bisimide, 12-membered rosettes that consist of alternating hydrogen-bonded OPV–melamine and perylene bisimide moieties are visualized. These results provide direct evidence for the possible modes of hydrogen bonding within a supramolecular co-assembly in solution. Subsequently, the optical properties of pure OPV–melamine and co-assemblies with a perylene bisimide derivative were characterized in solution. In an apolar solvent, OPV–melamine self-assembles into chiral superstructures. Disassembly into molecularly dissolved species is reversibly controlled by concentration and temperature. Complementary hydrogen bonding to a perylene bisimide derivative in an apolar solvent yields multicomponent, π-stacked dye assemblies of enhanced stability that are characterized by fluorescence quenching of the constituent chromophores. Titration experiments reveal that a mixture of hydrogen-bonded oligomers is present in solution, rather than a single discrete assembly. The solution experiments are consistent with the STM results, which revealed various supramolecular assemblies. Our system is likely not to be optimally programmed to obtain a discrete co-assembled structure in quantitative yield.}, author = {Hoeben, Freek J. M. and Zhang, Jian and Lee, Cameron C. and Pouderoijen, Maarten J. and Wolffs, Martin and Würthner, Frank and Schenning, Albertus P. H. J. and Meijer, E. W. and De Feyter, Steven}, journal = {Chemistry – A European Journal}, keywords = {myown}, number = 28, pages = {8579–8589}, publisher = {WILEY-VCH Verlag}, title = {Visualization of Various Supramolecular Assemblies of Oligo(para-phenylenevinylene)–Melamine and Perylene Bisimide}, volume = 14, year = 2008 }

  %0 Journal Article %1 CHEM:CHEM200800760 %A Hoeben, Freek J. M. %A Zhang, Jian %A Lee, Cameron C. %A Pouderoijen, Maarten J. %A Wolffs, Martin %A Würthner, Frank %A Schenning, Albertus P. H. J. %A Meijer, E. W. %A De Feyter, Steven %D 2008 %I WILEY-VCH Verlag %J Chemistry – A European Journal %N 28 %P 8579--8589 %R 10.1002/chem.200800760 %T Visualization of Various Supramolecular Assemblies of Oligo(para-phenylenevinylene)–Melamine and Perylene Bisimide %U http://dx.doi.org/10.1002/chem.200800760 %V 14 %X A melamine derivative has been covalently equipped with two oligo(para-phenylenevinylene) (OPV) chromophores. This procedure yields a bifunctional molecule with two hydrogen-bonding arrays available for complementary binding to perylene bisimide derivatives. Depending on the solvent, hydrogen-bonded trimers, tetramers, and dimers on a graphite surface are observed for pure OPV–melamine by using scanning tunneling microscopy (STM). Upon the addition of perylene bisimide, linear tapes of perylene bisimide, 12-membered rosettes that consist of alternating hydrogen-bonded OPV–melamine and perylene bisimide moieties are visualized. These results provide direct evidence for the possible modes of hydrogen bonding within a supramolecular co-assembly in solution. Subsequently, the optical properties of pure OPV–melamine and co-assemblies with a perylene bisimide derivative were characterized in solution. In an apolar solvent, OPV–melamine self-assembles into chiral superstructures. Disassembly into molecularly dissolved species is reversibly controlled by concentration and temperature. Complementary hydrogen bonding to a perylene bisimide derivative in an apolar solvent yields multicomponent, π-stacked dye assemblies of enhanced stability that are characterized by fluorescence quenching of the constituent chromophores. Titration experiments reveal that a mixture of hydrogen-bonded oligomers is present in solution, rather than a single discrete assembly. The solution experiments are consistent with the STM results, which revealed various supramolecular assemblies. Our system is likely not to be optimally programmed to obtain a discrete co-assembled structure in quantitative yield.
• Structure–Property Relationships for Self-Assembled Zinc Chlorin Light-Harvesting Dye Aggregates. Huber, Valerie; Sengupta, Sanchita; Würthner, Frank. In Chemistry – A European Journal, 14(26), pp. 7791–7807. 2008.
  • [ Abstract ]
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  A series of zinc 31-hydroxymethyl chlorins 10 a–e and zinc 31-hydroxyethyl chlorins 17 with varied structural features were synthesized by modifying naturally occurring chlorophyll a. Solvent-, temperature-, and concentration-dependent UV/Vis and CD spectroscopic methods as well as microscopic investigations were performed to explore the importance of particular functional groups and steric effects on the self-assembly behavior of these zinc chlorins. Semisynthetic zinc chlorins 10 a–e possess the three functional units relevant for self-assembly found in their natural bacteriochlorophyll (BChl) counterparts, namely, the 31-OH group, a central metal ion, and the 131 CO moiety along the Qy axis, and they contain various 172-substituents. Depending on whether the zinc chlorins have 172-hydrophobic or hydrophilic side chains, they self-assemble in nonpolar organic solvents or in aqueous media, respectively. Zinc chlorins possessing at least two long side chains provide soluble self-aggregates that are stable in solution for a prolonged time, thus facilitating elucidation of their properties by optical spectroscopy. The morphology of the zinc chlorin aggregates was elucidated by atomic force microscopy (AFM) studies, revealing well-defined nanoscale rod structures for zinc chlorin 10 b with a height of about 6 nm. It is worth noting that this size is in good accordance with a tubular arrangement of the dyes similar to that observed in their natural BChl counterparts in the light-harvesting chlorosomes of green bacteria. Furthermore, for the epimeric 31-hydroxyethyl zinc chlorins 17 with hydrophobic side chains, the influence of the chirality center at the 31-position on the aggregation behavior was studied in detail by UV/Vis and CD spectroscopy. Unlike zinc chlorins 10, the 31-hydroxyethyl zinc chlorins 17 formed only small oligomers and not higher rod aggregate structures, which can be attributed to the steric effect imposed by the additional methyl group at the 31-position.

  @article{CHEM:CHEM200800764, abstract = {A series of zinc 31-hydroxymethyl chlorins 10 a–e and zinc 31-hydroxyethyl chlorins 17 with varied structural features were synthesized by modifying naturally occurring chlorophyll a. Solvent-, temperature-, and concentration-dependent UV/Vis and CD spectroscopic methods as well as microscopic investigations were performed to explore the importance of particular functional groups and steric effects on the self-assembly behavior of these zinc chlorins. Semisynthetic zinc chlorins 10 a–e possess the three functional units relevant for self-assembly found in their natural bacteriochlorophyll (BChl) counterparts, namely, the 31-OH group, a central metal ion, and the 131 CO moiety along the Qy axis, and they contain various 172-substituents. Depending on whether the zinc chlorins have 172-hydrophobic or hydrophilic side chains, they self-assemble in nonpolar organic solvents or in aqueous media, respectively. Zinc chlorins possessing at least two long side chains provide soluble self-aggregates that are stable in solution for a prolonged time, thus facilitating elucidation of their properties by optical spectroscopy. The morphology of the zinc chlorin aggregates was elucidated by atomic force microscopy (AFM) studies, revealing well-defined nanoscale rod structures for zinc chlorin 10 b with a height of about 6 nm. It is worth noting that this size is in good accordance with a tubular arrangement of the dyes similar to that observed in their natural BChl counterparts in the light-harvesting chlorosomes of green bacteria. Furthermore, for the epimeric 31-hydroxyethyl zinc chlorins 17 with hydrophobic side chains, the influence of the chirality center at the 31-position on the aggregation behavior was studied in detail by UV/Vis and CD spectroscopy. Unlike zinc chlorins 10, the 31-hydroxyethyl zinc chlorins 17 formed only small oligomers and not higher rod aggregate structures, which can be attributed to the steric effect imposed by the additional methyl group at the 31-position.}, author = {Huber, Valerie and Sengupta, Sanchita and Würthner, Frank}, journal = {Chemistry – A European Journal}, keywords = {myown}, number = 26, pages = {7791–7807}, publisher = {WILEY-VCH Verlag}, title = {Structure–Property Relationships for Self-Assembled Zinc Chlorin Light-Harvesting Dye Aggregates}, volume = 14, year = 2008 }

  %0 Journal Article %1 CHEM:CHEM200800764 %A Huber, Valerie %A Sengupta, Sanchita %A Würthner, Frank %D 2008 %I WILEY-VCH Verlag %J Chemistry – A European Journal %N 26 %P 7791--7807 %R 10.1002/chem.200800764 %T Structure–Property Relationships for Self-Assembled Zinc Chlorin Light-Harvesting Dye Aggregates %U http://dx.doi.org/10.1002/chem.200800764 %V 14 %X A series of zinc 31-hydroxymethyl chlorins 10 a–e and zinc 31-hydroxyethyl chlorins 17 with varied structural features were synthesized by modifying naturally occurring chlorophyll a. Solvent-, temperature-, and concentration-dependent UV/Vis and CD spectroscopic methods as well as microscopic investigations were performed to explore the importance of particular functional groups and steric effects on the self-assembly behavior of these zinc chlorins. Semisynthetic zinc chlorins 10 a–e possess the three functional units relevant for self-assembly found in their natural bacteriochlorophyll (BChl) counterparts, namely, the 31-OH group, a central metal ion, and the 131 CO moiety along the Qy axis, and they contain various 172-substituents. Depending on whether the zinc chlorins have 172-hydrophobic or hydrophilic side chains, they self-assemble in nonpolar organic solvents or in aqueous media, respectively. Zinc chlorins possessing at least two long side chains provide soluble self-aggregates that are stable in solution for a prolonged time, thus facilitating elucidation of their properties by optical spectroscopy. The morphology of the zinc chlorin aggregates was elucidated by atomic force microscopy (AFM) studies, revealing well-defined nanoscale rod structures for zinc chlorin 10 b with a height of about 6 nm. It is worth noting that this size is in good accordance with a tubular arrangement of the dyes similar to that observed in their natural BChl counterparts in the light-harvesting chlorosomes of green bacteria. Furthermore, for the epimeric 31-hydroxyethyl zinc chlorins 17 with hydrophobic side chains, the influence of the chirality center at the 31-position on the aggregation behavior was studied in detail by UV/Vis and CD spectroscopy. Unlike zinc chlorins 10, the 31-hydroxyethyl zinc chlorins 17 formed only small oligomers and not higher rod aggregate structures, which can be attributed to the steric effect imposed by the additional methyl group at the 31-position.
• Photoinduced Energy and Electron-Transfer Processes in Porphyrin−Perylene Bisimide Symmetric Triads. Ghirotti, Marco; Chiorboli, Claudio; You, Chang-Cheng; Würthner, Frank; Scandola, Franco. In The Journal of Physical Chemistry A, 112(15), pp. 3376–3385. 2008.

  PMID: 18335911
  • [ Abstract ]
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  The photophysics of two symmetric triads, (ZnP)2PBI and (H2P)2PBI, made of two zinc or free-base porphyrins covalently attached to a central perylene bisimide unit has been investigated in dichloromethane and in toluene. The solvent has been shown to affect not only quantitatively but also qualitatively the photophysical behavior. A variety of intercomponent processes (singlet energy transfer, triplet energy transfer, photoinduced charge separation, and recombination) have been time-resolved using a combination of emission spectroscopy and femtosecond and nanosecond time-resolved absorption techniques yielding a very detailed picture of the photophysics of these systems. The singlet excited state of the lowest energy chromophore (perylene bisimide in the case of (ZnP)2PBI, porphyrin in the case of (H2P)2PBI) is always quantitatively populated, besides by direct light absorption, by ultrafast singlet energy transfer (few picosecond time constant) from the higher energy chromophore. In dichloromethane, the lowest excited singlet state is efficiently quenched by electron transfer leading to a charge-separated state where the porphyrin is oxidized and the perylene bisimide is reduced. The systems then go back to the ground state by charge recombination. The four charge separation and recombination processes observed for (ZnP)2PBI and (H2P)2PBI in dichloromethane take place in the sub-nanosecond time scale. They obey standard free-energy correlations with charge separation lying in the normal regime and charge recombination in the Marcus inverted region. In less polar solvents, such as toluene, the energy of the charge-separated states is substantially lifted leading to sharp changes in photophysical mechanism. With (ZnP)2PBI, the electron-transfer quenching is still fast, but charge recombination takes place now in the nanosecond time scale and to triplet state products rather than to the ground state. Triplet−triplet energy transfer from the porphyrin to the perylene bisimide is also involved in the subsequent deactivation of the triplet manifold to the ground state. With (H2P)2PBI, on the other hand, the driving force for charge separation is too small for electron-transfer quenching, and the deactivation of the porphyrin excited singlet takes place via intersystem crossing to the triplet followed by triplet energy transfer to the perylene bisimide and final decay to the ground state.

  @article{doi:10.1021/jp7109516, abstract = {The photophysics of two symmetric triads, (ZnP)2PBI and (H2P)2PBI, made of two zinc or free-base porphyrins covalently attached to a central perylene bisimide unit has been investigated in dichloromethane and in toluene. The solvent has been shown to affect not only quantitatively but also qualitatively the photophysical behavior. A variety of intercomponent processes (singlet energy transfer, triplet energy transfer, photoinduced charge separation, and recombination) have been time-resolved using a combination of emission spectroscopy and femtosecond and nanosecond time-resolved absorption techniques yielding a very detailed picture of the photophysics of these systems. The singlet excited state of the lowest energy chromophore (perylene bisimide in the case of (ZnP)2PBI, porphyrin in the case of (H2P)2PBI) is always quantitatively populated, besides by direct light absorption, by ultrafast singlet energy transfer (few picosecond time constant) from the higher energy chromophore. In dichloromethane, the lowest excited singlet state is efficiently quenched by electron transfer leading to a charge-separated state where the porphyrin is oxidized and the perylene bisimide is reduced. The systems then go back to the ground state by charge recombination. The four charge separation and recombination processes observed for (ZnP)2PBI and (H2P)2PBI in dichloromethane take place in the sub-nanosecond time scale. They obey standard free-energy correlations with charge separation lying in the normal regime and charge recombination in the Marcus inverted region. In less polar solvents, such as toluene, the energy of the charge-separated states is substantially lifted leading to sharp changes in photophysical mechanism. With (ZnP)2PBI, the electron-transfer quenching is still fast, but charge recombination takes place now in the nanosecond time scale and to triplet state products rather than to the ground state. Triplet−triplet energy transfer from the porphyrin to the perylene bisimide is also involved in the subsequent deactivation of the triplet manifold to the ground state. With (H2P)2PBI, on the other hand, the driving force for charge separation is too small for electron-transfer quenching, and the deactivation of the porphyrin excited singlet takes place via intersystem crossing to the triplet followed by triplet energy transfer to the perylene bisimide and final decay to the ground state.}, author = {Ghirotti, Marco and Chiorboli, Claudio and You, Chang-Cheng and Würthner, Frank and Scandola, Franco}, journal = {The Journal of Physical Chemistry A}, keywords = {myown}, note = {PMID: 18335911}, number = 15, pages = {3376-3385}, title = {Photoinduced Energy and Electron-Transfer Processes in Porphyrin−Perylene Bisimide Symmetric Triads}, volume = 112, year = 2008 }

  %0 Journal Article %1 doi:10.1021/jp7109516 %A Ghirotti, Marco %A Chiorboli, Claudio %A You, Chang-Cheng %A Würthner, Frank %A Scandola, Franco %D 2008 %J The Journal of Physical Chemistry A %N 15 %P 3376-3385 %R 10.1021/jp7109516 %T Photoinduced Energy and Electron-Transfer Processes in Porphyrin−Perylene Bisimide Symmetric Triads %U http://dx.doi.org/10.1021/jp7109516 %V 112 %X The photophysics of two symmetric triads, (ZnP)2PBI and (H2P)2PBI, made of two zinc or free-base porphyrins covalently attached to a central perylene bisimide unit has been investigated in dichloromethane and in toluene. The solvent has been shown to affect not only quantitatively but also qualitatively the photophysical behavior. A variety of intercomponent processes (singlet energy transfer, triplet energy transfer, photoinduced charge separation, and recombination) have been time-resolved using a combination of emission spectroscopy and femtosecond and nanosecond time-resolved absorption techniques yielding a very detailed picture of the photophysics of these systems. The singlet excited state of the lowest energy chromophore (perylene bisimide in the case of (ZnP)2PBI, porphyrin in the case of (H2P)2PBI) is always quantitatively populated, besides by direct light absorption, by ultrafast singlet energy transfer (few picosecond time constant) from the higher energy chromophore. In dichloromethane, the lowest excited singlet state is efficiently quenched by electron transfer leading to a charge-separated state where the porphyrin is oxidized and the perylene bisimide is reduced. The systems then go back to the ground state by charge recombination. The four charge separation and recombination processes observed for (ZnP)2PBI and (H2P)2PBI in dichloromethane take place in the sub-nanosecond time scale. They obey standard free-energy correlations with charge separation lying in the normal regime and charge recombination in the Marcus inverted region. In less polar solvents, such as toluene, the energy of the charge-separated states is substantially lifted leading to sharp changes in photophysical mechanism. With (ZnP)2PBI, the electron-transfer quenching is still fast, but charge recombination takes place now in the nanosecond time scale and to triplet state products rather than to the ground state. Triplet−triplet energy transfer from the porphyrin to the perylene bisimide is also involved in the subsequent deactivation of the triplet manifold to the ground state. With (H2P)2PBI, on the other hand, the driving force for charge separation is too small for electron-transfer quenching, and the deactivation of the porphyrin excited singlet takes place via intersystem crossing to the triplet followed by triplet energy transfer to the perylene bisimide and final decay to the ground state.
• Evolution of Homochiral Helical Dye Assemblies: Involvement of Autocatalysis in the "Majority-Rules" Effect. Lohr, A.; Würthner, F. In Angew. Chem. Int. Ed., 47, pp. 1232–1236. 2008.
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  @article{lohr2008evolution, author = {Lohr, A. and Würthner, F.}, journal = {Angew. Chem. Int. Ed.}, keywords = {myown}, pages = {1232–1236}, title = {Evolution of Homochiral Helical Dye Assemblies: Involvement of Autocatalysis in the "Majority-Rules" Effect}, volume = 47, year = 2008 }

  %0 Journal Article %1 lohr2008evolution %A Lohr, A. %A Würthner, F. %D 2008 %J Angew. Chem. Int. Ed. %P 1232–1236 %R 10.1002/anie.20070455 %T Evolution of Homochiral Helical Dye Assemblies: Involvement of Autocatalysis in the "Majority-Rules" Effect %U http://dx.doi.org/10.1002/anie.20070455 %V 47
• Photophysical study of bay substituted perylenediimides. Fron, Eduard; Schweitzer, Gerd; Osswald, Peter; Würthner, Frank; Marsal, Philippe; Beljonne, David; Mullen, Klaus; De Schryver, Frans C.; Van der Auweraer, Mark. In Photochem. Photobiol. Sci., 7(12), pp. 1509–1521. 2008.
  • [ Abstract ]
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  A detailed investigation of the photophysical properties of a series of perylenediimide systems bearing three different types of bay substituents is presented. Single photon timing and femtosecond transient absorption experiments reveal that the dynamics of interconversion between two conformational arrangements of these substituents occurs with a time constant of 550 ps. In addition, charge transfer from the electron-rich units attached to the bay area of the electron-poor perylenediimide core is observed. This process leads to a fast non-radiative deactivation of the locally excited state of the perylenediimide in polar solvents. When the experimental results of the investigated systems are compared we observe a shift from a conformational dynamics towards competitive excited state processes involving charge transfer in the -meta and -para substituted perylenediimide chromophore.

  @article{B813737D, abstract = {A detailed investigation of the photophysical properties of a series of perylenediimide systems bearing three different types of bay substituents is presented. Single photon timing and femtosecond transient absorption experiments reveal that the dynamics of interconversion between two conformational arrangements of these substituents occurs with a time constant of 550 ps. In addition{,} charge transfer from the electron-rich units attached to the bay area of the electron-poor perylenediimide core is observed. This process leads to a fast non-radiative deactivation of the locally excited state of the perylenediimide in polar solvents. When the experimental results of the investigated systems are compared we observe a shift from a conformational dynamics towards competitive excited state processes involving charge transfer in the -meta and -para substituted perylenediimide chromophore.}, author = {Fron, Eduard and Schweitzer, Gerd and Osswald, Peter and Würthner, Frank and Marsal, Philippe and Beljonne, David and Mullen, Klaus and De Schryver, Frans C. and Van der Auweraer, Mark}, journal = {Photochem. Photobiol. Sci.}, keywords = {myown}, number = 12, pages = {1509-1521}, publisher = {The Royal Society of Chemistry}, title = {Photophysical study of bay substituted perylenediimides}, volume = 7, year = 2008 }

  %0 Journal Article %1 B813737D %A Fron, Eduard %A Schweitzer, Gerd %A Osswald, Peter %A Würthner, Frank %A Marsal, Philippe %A Beljonne, David %A Mullen, Klaus %A De Schryver, Frans C. %A Van der Auweraer, Mark %D 2008 %I The Royal Society of Chemistry %J Photochem. Photobiol. Sci. %N 12 %P 1509-1521 %R 10.1039/B813737D %T Photophysical study of bay substituted perylenediimides %U http://dx.doi.org/10.1039/B813737D %V 7 %X A detailed investigation of the photophysical properties of a series of perylenediimide systems bearing three different types of bay substituents is presented. Single photon timing and femtosecond transient absorption experiments reveal that the dynamics of interconversion between two conformational arrangements of these substituents occurs with a time constant of 550 ps. In addition, charge transfer from the electron-rich units attached to the bay area of the electron-poor perylenediimide core is observed. This process leads to a fast non-radiative deactivation of the locally excited state of the perylenediimide in polar solvents. When the experimental results of the investigated systems are compared we observe a shift from a conformational dynamics towards competitive excited state processes involving charge transfer in the -meta and -para substituted perylenediimide chromophore.
• Control of H- and J-Type π Stacking by Peripheral Alkyl Chains and Self-Sorting Phenomena in Perylene Bisimide Homo- and Heteroaggregates. Ghosh, Suhrit; Li, Xue-Qing; Stepanenko, Vladimir; Würthner, Frank. In Chemistry – A European Journal, 14(36), pp. 11343–11357. 2008.
  • [ Abstract ]
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  The synthesis, self-assembly, and gelation ability of a series of organogelators based on perylene bisimide (PBI) dyes containing amide groups at imide positions are reported. The synergetic effect of intermolecular hydrogen bonding among the amide functionalities and π–π stacking between the PBI units directs the formation of the self-assembled structure in solution, which beyond a certain concentration results in gelation. Effects of different peripheral alkyl substituents on the self-assembly were studied by solvent- and temperature-dependent UV-visible and circular dichroism (CD) spectroscopy. PBI derivatives containing linear alkyl side chains in the periphery formed H-type π stacks and red gels, whereas by introducing branched alkyl chains the formation of J-type π stacks and green gels could be achieved. Sterically demanding substituents, in particular, the 2-ethylhexyl group completely suppressed the π stacking. Coaggregation studies with H- and J-aggregating chromophores revealed the formation of solely H-type π stacks containing both precursor molecules at a lower mole fraction of J-aggregating chromophore. Beyond a critical composition of the two chromophores, mixed H-aggregate and J-aggregate were formed simultaneously, which points to a self-sorting process. The versatility of the gelators is strongly dependent on the length and nature of the peripheral alkyl substituents. CD spectroscopic studies revealed a preferential helicity of the aggregates of PBI building blocks bearing chiral side chains. Even for achiral PBI derivatives, the utilization of chiral solvents such as (R)- or (S)-limonene was effective in preferential population of one-handed helical fibers. AFM studies revealed the formation of helical fibers from all the present PBI gelators, irrespective of the presence of chiral or achiral side chains. Furthermore, vortex flow was found to be effective in macroscopic orientation of the aggregates as evidenced from the origin of CD signals from aggregates of achiral PBI molecules.

  @article{CHEM:CHEM200801454, abstract = {The synthesis, self-assembly, and gelation ability of a series of organogelators based on perylene bisimide (PBI) dyes containing amide groups at imide positions are reported. The synergetic effect of intermolecular hydrogen bonding among the amide functionalities and π–π stacking between the PBI units directs the formation of the self-assembled structure in solution, which beyond a certain concentration results in gelation. Effects of different peripheral alkyl substituents on the self-assembly were studied by solvent- and temperature-dependent UV-visible and circular dichroism (CD) spectroscopy. PBI derivatives containing linear alkyl side chains in the periphery formed H-type π stacks and red gels, whereas by introducing branched alkyl chains the formation of J-type π stacks and green gels could be achieved. Sterically demanding substituents, in particular, the 2-ethylhexyl group completely suppressed the π stacking. Coaggregation studies with H- and J-aggregating chromophores revealed the formation of solely H-type π stacks containing both precursor molecules at a lower mole fraction of J-aggregating chromophore. Beyond a critical composition of the two chromophores, mixed H-aggregate and J-aggregate were formed simultaneously, which points to a self-sorting process. The versatility of the gelators is strongly dependent on the length and nature of the peripheral alkyl substituents. CD spectroscopic studies revealed a preferential helicity of the aggregates of PBI building blocks bearing chiral side chains. Even for achiral PBI derivatives, the utilization of chiral solvents such as (R)- or (S)-limonene was effective in preferential population of one-handed helical fibers. AFM studies revealed the formation of helical fibers from all the present PBI gelators, irrespective of the presence of chiral or achiral side chains. Furthermore, vortex flow was found to be effective in macroscopic orientation of the aggregates as evidenced from the origin of CD signals from aggregates of achiral PBI molecules.}, author = {Ghosh, Suhrit and Li, Xue-Qing and Stepanenko, Vladimir and Würthner, Frank}, journal = {Chemistry – A European Journal}, keywords = {myown}, number = 36, pages = {11343–11357}, publisher = {WILEY-VCH Verlag}, title = {Control of H- and J-Type π Stacking by Peripheral Alkyl Chains and Self-Sorting Phenomena in Perylene Bisimide Homo- and Heteroaggregates}, volume = 14, year = 2008 }

  %0 Journal Article %1 CHEM:CHEM200801454 %A Ghosh, Suhrit %A Li, Xue-Qing %A Stepanenko, Vladimir %A Würthner, Frank %D 2008 %I WILEY-VCH Verlag %J Chemistry – A European Journal %N 36 %P 11343--11357 %R 10.1002/chem.200801454 %T Control of H- and J-Type π Stacking by Peripheral Alkyl Chains and Self-Sorting Phenomena in Perylene Bisimide Homo- and Heteroaggregates %U http://dx.doi.org/10.1002/chem.200801454 %V 14 %X The synthesis, self-assembly, and gelation ability of a series of organogelators based on perylene bisimide (PBI) dyes containing amide groups at imide positions are reported. The synergetic effect of intermolecular hydrogen bonding among the amide functionalities and π–π stacking between the PBI units directs the formation of the self-assembled structure in solution, which beyond a certain concentration results in gelation. Effects of different peripheral alkyl substituents on the self-assembly were studied by solvent- and temperature-dependent UV-visible and circular dichroism (CD) spectroscopy. PBI derivatives containing linear alkyl side chains in the periphery formed H-type π stacks and red gels, whereas by introducing branched alkyl chains the formation of J-type π stacks and green gels could be achieved. Sterically demanding substituents, in particular, the 2-ethylhexyl group completely suppressed the π stacking. Coaggregation studies with H- and J-aggregating chromophores revealed the formation of solely H-type π stacks containing both precursor molecules at a lower mole fraction of J-aggregating chromophore. Beyond a critical composition of the two chromophores, mixed H-aggregate and J-aggregate were formed simultaneously, which points to a self-sorting process. The versatility of the gelators is strongly dependent on the length and nature of the peripheral alkyl substituents. CD spectroscopic studies revealed a preferential helicity of the aggregates of PBI building blocks bearing chiral side chains. Even for achiral PBI derivatives, the utilization of chiral solvents such as (R)- or (S)-limonene was effective in preferential population of one-handed helical fibers. AFM studies revealed the formation of helical fibers from all the present PBI gelators, irrespective of the presence of chiral or achiral side chains. Furthermore, vortex flow was found to be effective in macroscopic orientation of the aggregates as evidenced from the origin of CD signals from aggregates of achiral PBI molecules.
• Toward Fluorescent Memories with Nondestructive Readout: Photoswitching of Fluorescence by Intramolecular Electron Transfer in a Diaryl Ethene-Perylene Bisimide Photochromic System. Berberich, Martin; Krause, Ana-Maria; Orlandi, Michele; Scandola, Franco; Würthner, Frank. In Angew. Chem. Int. Ed., 47(35), pp. 6616–6619. 2008.
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  • [ DOI ]
  @article{berberich2008toward, author = {Berberich, Martin and Krause, Ana-Maria and Orlandi, Michele and Scandola, Franco and Würthner, Frank}, journal = {Angew. Chem. Int. Ed.}, keywords = {myown}, number = 35, pages = {6616 - 6619}, publisher = {WILEY-VCH Verlag}, title = {Toward Fluorescent Memories with Nondestructive Readout: Photoswitching of Fluorescence by Intramolecular Electron Transfer in a Diaryl Ethene-Perylene Bisimide Photochromic System}, volume = 47, year = 2008 }

  %0 Journal Article %1 berberich2008toward %A Berberich, Martin %A Krause, Ana-Maria %A Orlandi, Michele %A Scandola, Franco %A Würthner, Frank %D 2008 %I WILEY-VCH Verlag %J Angew. Chem. Int. Ed. %N 35 %P 6616 - 6619 %R 10.1002/anie.200802007 %T Toward Fluorescent Memories with Nondestructive Readout: Photoswitching of Fluorescence by Intramolecular Electron Transfer in a Diaryl Ethene-Perylene Bisimide Photochromic System %U https://onlinelibrary.wiley.com/doi/full/10.1002/anie.200802007 %V 47
• Three-Dimensional Molecular Packing of Thin Organic Films of PTCDI-C8 Determined by Surface X-ray Diffraction. Krauss, Tobias N.; Barrena, Esther; Zhang, Xue N.; de Oteyza, Dimas G.; Major, János; Dehm, Volker; Würthner, Frank; Cavalcanti, Leide P.; Dosch, Helmut. In Langmuir, 24(22), pp. 12742–12744. 2008.
  • [ Abstract ]
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  We have determined the full molecular 3D packing of thin organic films of the archetypical organic n-type semiconductor N,N′-dioctyl-3,4:9,10-perylene tetracarboxylic diimide (PTCDI-C8) by surface X-ray crystallography. We show that PTCDI-C8 forms smooth layered films on Al2O3 (11−20) with an outstanding degree of molecular order. The thin-film structure is found to consist of a triclinic unit cell with the plane of the aromatic core tilted by 67 ± 2° with respect to the surface plane, which differs significantly from the bulk structure. The 3D crystallites extend with vertical coherent order across the entire film thickness.

  @article{doi:10.1021/la8030182, abstract = {We have determined the full molecular 3D packing of thin organic films of the archetypical organic n-type semiconductor N,N′-dioctyl-3,4:9,10-perylene tetracarboxylic diimide (PTCDI-C8) by surface X-ray crystallography. We show that PTCDI-C8 forms smooth layered films on Al2O3 (11−20) with an outstanding degree of molecular order. The thin-film structure is found to consist of a triclinic unit cell with the plane of the aromatic core tilted by 67 ± 2° with respect to the surface plane, which differs significantly from the bulk structure. The 3D crystallites extend with vertical coherent order across the entire film thickness.}, author = {Krauss, Tobias N. and Barrena, Esther and Zhang, Xue N. and de Oteyza, Dimas G. and Major, János and Dehm, Volker and Würthner, Frank and Cavalcanti, Leide P. and Dosch, Helmut}, journal = {Langmuir}, keywords = {myown}, number = 22, pages = {12742-12744}, title = {Three-Dimensional Molecular Packing of Thin Organic Films of PTCDI-C8 Determined by Surface X-ray Diffraction}, volume = 24, year = 2008 }

  %0 Journal Article %1 doi:10.1021/la8030182 %A Krauss, Tobias N. %A Barrena, Esther %A Zhang, Xue N. %A de Oteyza, Dimas G. %A Major, János %A Dehm, Volker %A Würthner, Frank %A Cavalcanti, Leide P. %A Dosch, Helmut %D 2008 %J Langmuir %N 22 %P 12742-12744 %R 10.1021/la8030182 %T Three-Dimensional Molecular Packing of Thin Organic Films of PTCDI-C8 Determined by Surface X-ray Diffraction %U http://dx.doi.org/10.1021/la8030182 %V 24 %X We have determined the full molecular 3D packing of thin organic films of the archetypical organic n-type semiconductor N,N′-dioctyl-3,4:9,10-perylene tetracarboxylic diimide (PTCDI-C8) by surface X-ray crystallography. We show that PTCDI-C8 forms smooth layered films on Al2O3 (11−20) with an outstanding degree of molecular order. The thin-film structure is found to consist of a triclinic unit cell with the plane of the aromatic core tilted by 67 ± 2° with respect to the surface plane, which differs significantly from the bulk structure. The 3D crystallites extend with vertical coherent order across the entire film thickness.
• Circular dichroism spectroscopy of small molecular aggregates: Dynamical features and size effects. Seibt, Joachim; Dehm, Volker; Würthner, Frank; Engel, Volker. In The Journal of Chemical Physics, 128(20), p. 204303. 2008.
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  @article{doi:10.1063/1.2927301, author = {Seibt, Joachim and Dehm, Volker and Würthner, Frank and Engel, Volker}, journal = {The Journal of Chemical Physics}, keywords = {myown}, number = 20, pages = 204303, title = {Circular dichroism spectroscopy of small molecular aggregates: Dynamical features and size effects}, volume = 128, year = 2008 }

  %0 Journal Article %1 doi:10.1063/1.2927301 %A Seibt, Joachim %A Dehm, Volker %A Würthner, Frank %A Engel, Volker %D 2008 %J The Journal of Chemical Physics %N 20 %P 204303 %R 10.1063/1.2927301 %T Circular dichroism spectroscopy of small molecular aggregates: Dynamical features and size effects %U https://doi.org/10.1063/1.2927301 %V 128
• Synthesis, Optical Properties, and LFER Analysis of Solvent-Dependent Binding Constants of Hamilton-Receptor-Connected Merocyanine Chromophores. Schmidt, Johann; Schmidt, Ralf; Würthner, Frank. In The Journal of Organic Chemistry, 73(16), pp. 6355–6362. 2008.

  PMID: 18642873
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  A merocyanine dye equipped with a Hamilton-receptor unit has been synthesized that enables strong noncovalent binding of other merocyanine dyes bearing barbituric acid acceptor groups by six hydrogen bonds. NMR and UV/vis titration experiments in toluene, chloroform, dichloromethane, dioxane, and THF provide evidence for the formation of 1:1 complexes even in the dipolar solvents. An enhanced binding strength is observed for the more dipolar merocyanine dyes in the head-to-tail assembly structure with binding constants up to >108 M−1 in toluene. In the present bimolecular complexes two merocyanine chromophores are assembled in a head-to-tail fashion that affords increased dipole moments as demanded for efficient electric field induced poling processes in nonlinear optical and photorefractive polymeric hosts. The solvent dependency of the binding constants for various barbituric acid dye−Hamilton receptor complexes as well as a perylene imide−melamine complex reveals linear free energy relationships (LFER) that allow for an estimation of binding constants larger than 1012 M−1 for Hamilton receptor organized head-to-tail merocyanine bimolecular complexes in aliphatic solvents. It is suggested that such LFER are valuable tools for the estimation of binding constants in solvents where experimental binding constants cannot be determined because of solubility or spectroscopic problems.

  @article{doi:10.1021/jo801083b, abstract = {A merocyanine dye equipped with a Hamilton-receptor unit has been synthesized that enables strong noncovalent binding of other merocyanine dyes bearing barbituric acid acceptor groups by six hydrogen bonds. NMR and UV/vis titration experiments in toluene, chloroform, dichloromethane, dioxane, and THF provide evidence for the formation of 1:1 complexes even in the dipolar solvents. An enhanced binding strength is observed for the more dipolar merocyanine dyes in the head-to-tail assembly structure with binding constants up to >108 M−1 in toluene. In the present bimolecular complexes two merocyanine chromophores are assembled in a head-to-tail fashion that affords increased dipole moments as demanded for efficient electric field induced poling processes in nonlinear optical and photorefractive polymeric hosts. The solvent dependency of the binding constants for various barbituric acid dye−Hamilton receptor complexes as well as a perylene imide−melamine complex reveals linear free energy relationships (LFER) that allow for an estimation of binding constants larger than 1012 M−1 for Hamilton receptor organized head-to-tail merocyanine bimolecular complexes in aliphatic solvents. It is suggested that such LFER are valuable tools for the estimation of binding constants in solvents where experimental binding constants cannot be determined because of solubility or spectroscopic problems.}, author = {Schmidt, Johann and Schmidt, Ralf and Würthner, Frank}, journal = {The Journal of Organic Chemistry}, keywords = {myown}, note = {PMID: 18642873}, number = 16, pages = {6355-6362}, title = {Synthesis, Optical Properties, and LFER Analysis of Solvent-Dependent Binding Constants of Hamilton-Receptor-Connected Merocyanine Chromophores}, volume = 73, year = 2008 }

  %0 Journal Article %1 doi:10.1021/jo801083b %A Schmidt, Johann %A Schmidt, Ralf %A Würthner, Frank %D 2008 %J The Journal of Organic Chemistry %N 16 %P 6355-6362 %R 10.1021/jo801083b %T Synthesis, Optical Properties, and LFER Analysis of Solvent-Dependent Binding Constants of Hamilton-Receptor-Connected Merocyanine Chromophores %U http://dx.doi.org/10.1021/jo801083b %V 73 %X A merocyanine dye equipped with a Hamilton-receptor unit has been synthesized that enables strong noncovalent binding of other merocyanine dyes bearing barbituric acid acceptor groups by six hydrogen bonds. NMR and UV/vis titration experiments in toluene, chloroform, dichloromethane, dioxane, and THF provide evidence for the formation of 1:1 complexes even in the dipolar solvents. An enhanced binding strength is observed for the more dipolar merocyanine dyes in the head-to-tail assembly structure with binding constants up to >108 M−1 in toluene. In the present bimolecular complexes two merocyanine chromophores are assembled in a head-to-tail fashion that affords increased dipole moments as demanded for efficient electric field induced poling processes in nonlinear optical and photorefractive polymeric hosts. The solvent dependency of the binding constants for various barbituric acid dye−Hamilton receptor complexes as well as a perylene imide−melamine complex reveals linear free energy relationships (LFER) that allow for an estimation of binding constants larger than 1012 M−1 for Hamilton receptor organized head-to-tail merocyanine bimolecular complexes in aliphatic solvents. It is suggested that such LFER are valuable tools for the estimation of binding constants in solvents where experimental binding constants cannot be determined because of solubility or spectroscopic problems.
• Hierarchical Self-Assembly of Cyclic Dye Arrays into Two-Dimensional Honeycomb Nanonetworks. Stepanenko, Vladimir; Würthner, Frank. In Small, 4(12), pp. 2158–2161. 2008.
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  @article{SMLL:SMLL200801069, author = {Stepanenko, Vladimir and Würthner, Frank}, journal = {Small}, keywords = {myown}, number = 12, pages = {2158–2161}, publisher = {WILEY-VCH Verlag}, title = {Hierarchical Self-Assembly of Cyclic Dye Arrays into Two-Dimensional Honeycomb Nanonetworks}, volume = 4, year = 2008 }

  %0 Journal Article %1 SMLL:SMLL200801069 %A Stepanenko, Vladimir %A Würthner, Frank %D 2008 %I WILEY-VCH Verlag %J Small %N 12 %P 2158--2161 %R 10.1002/smll.200801069 %T Hierarchical Self-Assembly of Cyclic Dye Arrays into Two-Dimensional Honeycomb Nanonetworks %U http://dx.doi.org/10.1002/smll.200801069 %V 4
• A New Type of Soft Vesicle-Forming Molecule:  An Amino Acid Derived Guanidiniocarbonyl Pyrrole Carboxylate Zwitterion. Rehm, Thomas; Stepanenko, Vladimir; Zhang, Xin; Würthner, Frank; Gröhn, Franziska; Klein, Katja; Schmuck, Carsten. In Organic Letters, 10(7), pp. 1469–1472. 2008.

  PMID: 18311995
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  The self-assembly of the l-alanine derived zwitterion 3 leads to the formation of soft vesicles in solution even though this surprisingly small molecule does not possess the classical amphiphilic features of other vesicle-forming monomers.

  @article{doi:10.1021/ol8002755, abstract = {The self-assembly of the l-alanine derived zwitterion 3 leads to the formation of soft vesicles in solution even though this surprisingly small molecule does not possess the classical amphiphilic features of other vesicle-forming monomers.}, author = {Rehm, Thomas and Stepanenko, Vladimir and Zhang, Xin and Würthner, Frank and Gröhn, Franziska and Klein, Katja and Schmuck, Carsten}, journal = {Organic Letters}, keywords = {myown}, note = {PMID: 18311995}, number = 7, pages = {1469-1472}, title = {A New Type of Soft Vesicle-Forming Molecule:  An Amino Acid Derived Guanidiniocarbonyl Pyrrole Carboxylate Zwitterion}, volume = 10, year = 2008 }

  %0 Journal Article %1 doi:10.1021/ol8002755 %A Rehm, Thomas %A Stepanenko, Vladimir %A Zhang, Xin %A Würthner, Frank %A Gröhn, Franziska %A Klein, Katja %A Schmuck, Carsten %D 2008 %J Organic Letters %N 7 %P 1469-1472 %R 10.1021/ol8002755 %T A New Type of Soft Vesicle-Forming Molecule:  An Amino Acid Derived Guanidiniocarbonyl Pyrrole Carboxylate Zwitterion %U http://dx.doi.org/10.1021/ol8002755 %V 10 %X The self-assembly of the l-alanine derived zwitterion 3 leads to the formation of soft vesicles in solution even though this surprisingly small molecule does not possess the classical amphiphilic features of other vesicle-forming monomers.
• Transformation from H- to J-Aggregated Perylene Bisimide Dyes by Complexation with Cyanurates. Yagai, Shiki; Seki, Tomohiro; Karatsu, Takashi; Kitamura, Akihide; Würthner, Frank. In Angew. Chem. Int. Ed., 47(18), pp. 3367–3371. 2008.
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  @article{ANIE:ANIE200705385, author = {Yagai, Shiki and Seki, Tomohiro and Karatsu, Takashi and Kitamura, Akihide and Würthner, Frank}, journal = {Angew. Chem. Int. Ed.}, keywords = {myown}, number = 18, pages = {3367–3371}, publisher = {WILEY-VCH Verlag}, title = {Transformation from H- to J-Aggregated Perylene Bisimide Dyes by Complexation with Cyanurates}, volume = 47, year = 2008 }

  %0 Journal Article %1 ANIE:ANIE200705385 %A Yagai, Shiki %A Seki, Tomohiro %A Karatsu, Takashi %A Kitamura, Akihide %A Würthner, Frank %D 2008 %I WILEY-VCH Verlag %J Angew. Chem. Int. Ed. %N 18 %P 3367--3371 %R 10.1002/anie.200705385 %T Transformation from H- to J-Aggregated Perylene Bisimide Dyes by Complexation with Cyanurates %U http://dx.doi.org/10.1002/anie.200705385 %V 47
• Bulk heterojunction organic solar cells based on merocyanine colorants. Kronenberg, Nils M.; Deppisch, Manuela; Würthner, Frank; Lademann, Hans W. A.; Deing, Kaja; Meerholz, Klaus. In Chem. Commun., (48), pp. 6489–6491. 2008.
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  Traditional low-molecular weight colorants that are widely applied in textile coloration, for printing purposes and nonlinear optics, now afford bulk heterojunction solar cells in combination with soluble C60fullerene derivative PCBM with power conversion efficiencies up to 1.7% under standard solar radiation.

  @article{B813341G, abstract = {Traditional low-molecular weight colorants that are widely applied in textile coloration{,} for printing purposes and nonlinear optics{,} now afford bulk heterojunction solar cells in combination with soluble C60fullerene derivative PCBM with power conversion efficiencies up to 1.7% under standard solar radiation.}, author = {Kronenberg, Nils M. and Deppisch, Manuela and Würthner, Frank and Lademann, Hans W. A. and Deing, Kaja and Meerholz, Klaus}, journal = {Chem. Commun.}, keywords = {myown}, number = 48, pages = {6489-6491}, publisher = {The Royal Society of Chemistry}, title = {Bulk heterojunction organic solar cells based on merocyanine colorants}, year = 2008 }

  %0 Journal Article %1 B813341G %A Kronenberg, Nils M. %A Deppisch, Manuela %A Würthner, Frank %A Lademann, Hans W. A. %A Deing, Kaja %A Meerholz, Klaus %D 2008 %I The Royal Society of Chemistry %J Chem. Commun. %N 48 %P 6489-6491 %R 10.1039/B813341G %T Bulk heterojunction organic solar cells based on merocyanine colorants %U http://dx.doi.org/10.1039/B813341G %X Traditional low-molecular weight colorants that are widely applied in textile coloration, for printing purposes and nonlinear optics, now afford bulk heterojunction solar cells in combination with soluble C60fullerene derivative PCBM with power conversion efficiencies up to 1.7% under standard solar radiation.
• Sequential FRET Processes in Calix[4]arene-Linked Orange-Red-Green Perylene Bisimide Dye Zigzag Arrays. Hippius, Catharina; van Stokkum, Ivo H. M.; Gsänger, Marcel; Groeneveld, Michiel M.; Williams, René M.; Würthner, Frank. In The Journal of Physical Chemistry C, 112(7), pp. 2476–2486. 2008.
  • [ Abstract ]
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  Perylene bisimide−calix[4]arene arrays composed of up to three different types of perylene bisimide chromophores (orange, red, and green PBIs) have been synthesized. Within these arrays, the individual chromophoric building blocks are positioned in defined spatial orientation and are easily replaceable by each other without influencing the overall geometric arrangement of the supramolecular system. The specific optical properties of the individual chromophore facilitated the investigation of photoinduced processes very accurately by time-resolved emission and femtosecond transient absorption spectroscopy. A quantitative analysis of the photophysical processes as well as their rate constants have been obtained by employing UV/vis absorption, steady state and time-resolved emission, femtosecond transient absorption spectroscopy, and spectrotemporal analysis of the femtosecond transient absorption data. These studies reveal very efficient energy transfer processes from the orange to the red PBI chromophoric unit (kET = 6.4 × 1011 s-1 for array or), from the red to the green PBI (kET = 4.0 × 1011s-1 for array rg), and slightly less efficient from the orange to the green PBI (kET = 1.5 × 1011s-1 for array og) within these perylene bisimide−calix[4]arene arrays. The experimentally obtained rate constants for the energy transfer processes are in very good agreement with those calculated according to the Förster theory.

  @article{doi:10.1021/jp711120v, abstract = {Perylene bisimide−calix[4]arene arrays composed of up to three different types of perylene bisimide chromophores (orange, red, and green PBIs) have been synthesized. Within these arrays, the individual chromophoric building blocks are positioned in defined spatial orientation and are easily replaceable by each other without influencing the overall geometric arrangement of the supramolecular system. The specific optical properties of the individual chromophore facilitated the investigation of photoinduced processes very accurately by time-resolved emission and femtosecond transient absorption spectroscopy. A quantitative analysis of the photophysical processes as well as their rate constants have been obtained by employing UV/vis absorption, steady state and time-resolved emission, femtosecond transient absorption spectroscopy, and spectrotemporal analysis of the femtosecond transient absorption data. These studies reveal very efficient energy transfer processes from the orange to the red PBI chromophoric unit (kET = 6.4 × 1011 s-1 for array or), from the red to the green PBI (kET = 4.0 × 1011s-1 for array rg), and slightly less efficient from the orange to the green PBI (kET = 1.5 × 1011s-1 for array og) within these perylene bisimide−calix[4]arene arrays. The experimentally obtained rate constants for the energy transfer processes are in very good agreement with those calculated according to the Förster theory.}, author = {Hippius, Catharina and van Stokkum, Ivo H. M. and Gsänger, Marcel and Groeneveld, Michiel M. and Williams, René M. and Würthner, Frank}, journal = {The Journal of Physical Chemistry C}, keywords = {myown}, number = 7, pages = {2476-2486}, title = {Sequential FRET Processes in Calix[4]arene-Linked Orange-Red-Green Perylene Bisimide Dye Zigzag Arrays}, volume = 112, year = 2008 }

  %0 Journal Article %1 doi:10.1021/jp711120v %A Hippius, Catharina %A van Stokkum, Ivo H. M. %A Gsänger, Marcel %A Groeneveld, Michiel M. %A Williams, René M. %A Würthner, Frank %D 2008 %J The Journal of Physical Chemistry C %N 7 %P 2476-2486 %R 10.1021/jp711120v %T Sequential FRET Processes in Calix[4]arene-Linked Orange-Red-Green Perylene Bisimide Dye Zigzag Arrays %U http://dx.doi.org/10.1021/jp711120v %V 112 %X Perylene bisimide−calix[4]arene arrays composed of up to three different types of perylene bisimide chromophores (orange, red, and green PBIs) have been synthesized. Within these arrays, the individual chromophoric building blocks are positioned in defined spatial orientation and are easily replaceable by each other without influencing the overall geometric arrangement of the supramolecular system. The specific optical properties of the individual chromophore facilitated the investigation of photoinduced processes very accurately by time-resolved emission and femtosecond transient absorption spectroscopy. A quantitative analysis of the photophysical processes as well as their rate constants have been obtained by employing UV/vis absorption, steady state and time-resolved emission, femtosecond transient absorption spectroscopy, and spectrotemporal analysis of the femtosecond transient absorption data. These studies reveal very efficient energy transfer processes from the orange to the red PBI chromophoric unit (kET = 6.4 × 1011 s-1 for array or), from the red to the green PBI (kET = 4.0 × 1011s-1 for array rg), and slightly less efficient from the orange to the green PBI (kET = 1.5 × 1011s-1 for array og) within these perylene bisimide−calix[4]arene arrays. The experimentally obtained rate constants for the energy transfer processes are in very good agreement with those calculated according to the Förster theory.
• Solvent Effect on Color, Band Shape, and Charge-Density Distribution for Merocyanine Dyes Close to the Cyanine Limit. Würthner, Frank; Archetti, Graziano; Schmidt, Ralf; Kuball, Hans-Georg. In Angew. Chem. Int. Ed., 47(24), pp. 4529–4532. 2008.
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  @article{ANIE:ANIE200800279, author = {Würthner, Frank and Archetti, Graziano and Schmidt, Ralf and Kuball, Hans-Georg}, journal = {Angew. Chem. Int. Ed.}, keywords = {myown}, number = 24, pages = {4529–4532}, publisher = {WILEY-VCH Verlag}, title = {Solvent Effect on Color, Band Shape, and Charge-Density Distribution for Merocyanine Dyes Close to the Cyanine Limit}, volume = 47, year = 2008 }

  %0 Journal Article %1 ANIE:ANIE200800279 %A Würthner, Frank %A Archetti, Graziano %A Schmidt, Ralf %A Kuball, Hans-Georg %D 2008 %I WILEY-VCH Verlag %J Angew. Chem. Int. Ed. %N 24 %P 4529--4532 %R 10.1002/anie.200800279 %T Solvent Effect on Color, Band Shape, and Charge-Density Distribution for Merocyanine Dyes Close to the Cyanine Limit %U http://dx.doi.org/10.1002/anie.200800279 %V 47
• Ground- and Excited-State Pinched Cone Equilibria in Calix[4]arenes Bearing Two Perylene Bisimide Dyes. Hippius, Catharina; van Stokkum, Ivo H. M.; Zangrando, Ennio; Williams, René M.; Wykes, Michael; Beljonne, David; Würthner, Frank. In The Journal of Physical Chemistry C, 112(37), pp. 14626–14638. 2008.
  • [ Abstract ]
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  We report on a series of bis-chromophoric compounds o2c, g2c, and r2c, afforded by linking two identical orange, green, or red perylene bisimide (PBI) units, respectively, through a calix[4]arene spacer unit. The PBI units are characterized by their increasing sterical demand from a planar conformation, which is orange (o) colored, via the slightly distorted greenish (g) colored form to the strongly distorted derivative, which is red (r) colored. An equilibrium between the two possible pinched cone conformations of the calix[4]arene unit is observed for all three compounds, with one conformation showing a π-stacked sandwich arrangement of the PBI units and the second revealing a nonstacked conformation. The amount of the π-stacked conformation in the equilibrium enhances upon decreasing the steric encumbering of the respective PBI unit as well as upon lowering the solvent polarity, thus increasing π−π interactions as well as electronic coupling between the PBI units. Accordingly, the presence of the π-stacked calix[4]arene conformation is most pronounced for compound o2c in methylcyclohexane (MCH), CCl4, and toluene, and to a lesser extent for compound g2c in MCH. Almost no π-stacked conformation is found for the most sterically demanding red system r2c. Molecular modeling studies at the force-field level show that the π-stacked conformations of the least sterically hindered dimmer o2c are lower in energy than those of the nonstacked ones in a nonpolar environment, whereas, in polar media, these stabilities are inversed. A quantitative analysis of the excited-state properties has been obtained by UV/vis absorption, steady-state and time-resolved emission, and femtosecond transient absorption spectroscopy. Global and target analysis of the femtosecond transient absorption data is used for probing ground-state populations with excited-state dynamics. The o2c molecules in the π-stacked conformation display a distinctly different decay behavior relative to the molecules in the nonstacked conformation. The former population decays via an excimer state, with the latter population decays through a charge separation process involving the calix[4]arene as a donor.

  @article{doi:10.1021/jp804068b, abstract = {We report on a series of bis-chromophoric compounds o2c, g2c, and r2c, afforded by linking two identical orange, green, or red perylene bisimide (PBI) units, respectively, through a calix[4]arene spacer unit. The PBI units are characterized by their increasing sterical demand from a planar conformation, which is orange (o) colored, via the slightly distorted greenish (g) colored form to the strongly distorted derivative, which is red (r) colored. An equilibrium between the two possible pinched cone conformations of the calix[4]arene unit is observed for all three compounds, with one conformation showing a π-stacked sandwich arrangement of the PBI units and the second revealing a nonstacked conformation. The amount of the π-stacked conformation in the equilibrium enhances upon decreasing the steric encumbering of the respective PBI unit as well as upon lowering the solvent polarity, thus increasing π−π interactions as well as electronic coupling between the PBI units. Accordingly, the presence of the π-stacked calix[4]arene conformation is most pronounced for compound o2c in methylcyclohexane (MCH), CCl4, and toluene, and to a lesser extent for compound g2c in MCH. Almost no π-stacked conformation is found for the most sterically demanding red system r2c. Molecular modeling studies at the force-field level show that the π-stacked conformations of the least sterically hindered dimmer o2c are lower in energy than those of the nonstacked ones in a nonpolar environment, whereas, in polar media, these stabilities are inversed. A quantitative analysis of the excited-state properties has been obtained by UV/vis absorption, steady-state and time-resolved emission, and femtosecond transient absorption spectroscopy. Global and target analysis of the femtosecond transient absorption data is used for probing ground-state populations with excited-state dynamics. The o2c molecules in the π-stacked conformation display a distinctly different decay behavior relative to the molecules in the nonstacked conformation. The former population decays via an excimer state, with the latter population decays through a charge separation process involving the calix[4]arene as a donor.}, author = {Hippius, Catharina and van Stokkum, Ivo H. M. and Zangrando, Ennio and Williams, René M. and Wykes, Michael and Beljonne, David and Würthner, Frank}, journal = {The Journal of Physical Chemistry C}, keywords = {myown}, number = 37, pages = {14626-14638}, title = {Ground- and Excited-State Pinched Cone Equilibria in Calix[4]arenes Bearing Two Perylene Bisimide Dyes}, volume = 112, year = 2008 }

  %0 Journal Article %1 doi:10.1021/jp804068b %A Hippius, Catharina %A van Stokkum, Ivo H. M. %A Zangrando, Ennio %A Williams, René M. %A Wykes, Michael %A Beljonne, David %A Würthner, Frank %D 2008 %J The Journal of Physical Chemistry C %N 37 %P 14626-14638 %R 10.1021/jp804068b %T Ground- and Excited-State Pinched Cone Equilibria in Calix[4]arenes Bearing Two Perylene Bisimide Dyes %U http://dx.doi.org/10.1021/jp804068b %V 112 %X We report on a series of bis-chromophoric compounds o2c, g2c, and r2c, afforded by linking two identical orange, green, or red perylene bisimide (PBI) units, respectively, through a calix[4]arene spacer unit. The PBI units are characterized by their increasing sterical demand from a planar conformation, which is orange (o) colored, via the slightly distorted greenish (g) colored form to the strongly distorted derivative, which is red (r) colored. An equilibrium between the two possible pinched cone conformations of the calix[4]arene unit is observed for all three compounds, with one conformation showing a π-stacked sandwich arrangement of the PBI units and the second revealing a nonstacked conformation. The amount of the π-stacked conformation in the equilibrium enhances upon decreasing the steric encumbering of the respective PBI unit as well as upon lowering the solvent polarity, thus increasing π−π interactions as well as electronic coupling between the PBI units. Accordingly, the presence of the π-stacked calix[4]arene conformation is most pronounced for compound o2c in methylcyclohexane (MCH), CCl4, and toluene, and to a lesser extent for compound g2c in MCH. Almost no π-stacked conformation is found for the most sterically demanding red system r2c. Molecular modeling studies at the force-field level show that the π-stacked conformations of the least sterically hindered dimmer o2c are lower in energy than those of the nonstacked ones in a nonpolar environment, whereas, in polar media, these stabilities are inversed. A quantitative analysis of the excited-state properties has been obtained by UV/vis absorption, steady-state and time-resolved emission, and femtosecond transient absorption spectroscopy. Global and target analysis of the femtosecond transient absorption data is used for probing ground-state populations with excited-state dynamics. The o2c molecules in the π-stacked conformation display a distinctly different decay behavior relative to the molecules in the nonstacked conformation. The former population decays via an excimer state, with the latter population decays through a charge separation process involving the calix[4]arene as a donor.

• Excited State Interactions in Calix[4]arene−Perylene Bisimide Dye Conjugates:  Global and Target Analysis of Supramolecular Building Blocks. Hippius, Catharina; van Stokkum, Ivo H. M.; Zangrando, E.; Williams, René M.; Würthner, Frank. In J. Phys. Chem. C., 111(37), pp. 13988–13996. 2007.
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  The photophysical properties of two supramolecular building blocks oc and oc2 consisting of a perylene bisimide chromophore substituted with either one or two calix[4]arene units in the N-imide position as well as those of the reference compound oref without calix[4]arene substituents were investigated. A complete picture of the processes taking place after photoexcitation in toluene, CH2Cl2, and benzonitrile was obtained by means of UV/vis absorption, steady state and time-resolved emission, and femtosecond transient absorption spectroscopy. It has been found that the fluorescence emission of compounds oc (Φfl = 0.03 in CH2Cl2) and oc2 (Φfl < 0.01 in CH2Cl2) is almost completely quenched compared with the highly emissive reference compound oref (Φfl = 0.99 in CH2Cl2) because of fast electron-transfer processes from the calix[4]arene moieties to the perylene bisimide chromophore. This predominantly takes place with rate constants of kCS = 3 × 1010 s-1 (τCS = 32 ps) for compound oc and kCS = 9 × 1010 s-1 (τCS = 11 ps) for compound oc2 (in CH2Cl2) leading to a short-lived charge-separated state consisting of the reduced perylene bisimide unit and the oxidized calix[4]arene moiety.

  @article{doi:10.1021/jp0733825, abstract = {The photophysical properties of two supramolecular building blocks oc and oc2 consisting of a perylene bisimide chromophore substituted with either one or two calix[4]arene units in the N-imide position as well as those of the reference compound oref without calix[4]arene substituents were investigated. A complete picture of the processes taking place after photoexcitation in toluene, CH2Cl2, and benzonitrile was obtained by means of UV/vis absorption, steady state and time-resolved emission, and femtosecond transient absorption spectroscopy. It has been found that the fluorescence emission of compounds oc (Φfl = 0.03 in CH2Cl2) and oc2 (Φfl < 0.01 in CH2Cl2) is almost completely quenched compared with the highly emissive reference compound oref (Φfl = 0.99 in CH2Cl2) because of fast electron-transfer processes from the calix[4]arene moieties to the perylene bisimide chromophore. This predominantly takes place with rate constants of kCS = 3 × 1010 s-1 (τCS = 32 ps) for compound oc and kCS = 9 × 1010 s-1 (τCS = 11 ps) for compound oc2 (in CH2Cl2) leading to a short-lived charge-separated state consisting of the reduced perylene bisimide unit and the oxidized calix[4]arene moiety.}, author = {Hippius, Catharina and van Stokkum, Ivo H. M. and Zangrando, E. and Williams, René M. and Würthner, Frank}, journal = {J. Phys. Chem. C.}, keywords = {myown}, number = 37, pages = {13988-13996}, title = {Excited State Interactions in Calix[4]arene−Perylene Bisimide Dye Conjugates:  Global and Target Analysis of Supramolecular Building Blocks}, volume = 111, year = 2007 }

  %0 Journal Article %1 doi:10.1021/jp0733825 %A Hippius, Catharina %A van Stokkum, Ivo H. M. %A Zangrando, E. %A Williams, René M. %A Würthner, Frank %D 2007 %J J. Phys. Chem. C. %N 37 %P 13988-13996 %R 10.1021/jp0733825 %T Excited State Interactions in Calix[4]arene−Perylene Bisimide Dye Conjugates:  Global and Target Analysis of Supramolecular Building Blocks %U http://dx.doi.org/10.1021/jp0733825 %V 111 %X The photophysical properties of two supramolecular building blocks oc and oc2 consisting of a perylene bisimide chromophore substituted with either one or two calix[4]arene units in the N-imide position as well as those of the reference compound oref without calix[4]arene substituents were investigated. A complete picture of the processes taking place after photoexcitation in toluene, CH2Cl2, and benzonitrile was obtained by means of UV/vis absorption, steady state and time-resolved emission, and femtosecond transient absorption spectroscopy. It has been found that the fluorescence emission of compounds oc (Φfl = 0.03 in CH2Cl2) and oc2 (Φfl < 0.01 in CH2Cl2) is almost completely quenched compared with the highly emissive reference compound oref (Φfl = 0.99 in CH2Cl2) because of fast electron-transfer processes from the calix[4]arene moieties to the perylene bisimide chromophore. This predominantly takes place with rate constants of kCS = 3 × 1010 s-1 (τCS = 32 ps) for compound oc and kCS = 9 × 1010 s-1 (τCS = 11 ps) for compound oc2 (in CH2Cl2) leading to a short-lived charge-separated state consisting of the reduced perylene bisimide unit and the oxidized calix[4]arene moiety.
• Supramolecular Construction of Fluorescent J-Aggregates Based on Hydrogen-Bonded Perylene Dyes. Kaiser, Theo E.; Wang, Hao; Stepanenko, Vladimir; Würthner, Frank. In Angew. Chem. Int. Ed., 46(29), pp. 5541–5544. 2007.
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  @article{ANIE:ANIE200701139, author = {Kaiser, Theo E. and Wang, Hao and Stepanenko, Vladimir and Würthner, Frank}, journal = {Angew. Chem. Int. Ed.}, keywords = {myown}, number = 29, pages = {5541–5544}, publisher = {WILEY-VCH Verlag}, title = {Supramolecular Construction of Fluorescent J-Aggregates Based on Hydrogen-Bonded Perylene Dyes}, volume = 46, year = 2007 }

  %0 Journal Article %1 ANIE:ANIE200701139 %A Kaiser, Theo E. %A Wang, Hao %A Stepanenko, Vladimir %A Würthner, Frank %D 2007 %I WILEY-VCH Verlag %J Angew. Chem. Int. Ed. %N 29 %P 5541--5544 %R 10.1002/anie.200701139 %T Supramolecular Construction of Fluorescent J-Aggregates Based on Hydrogen-Bonded Perylene Dyes %U http://dx.doi.org/10.1002/anie.200701139 %V 46
• Photophysical Characterization of a Light-Harvesting Tetra Naphthalene Imide/Perylene Bisimide Array. Flamigni, Lucia; Ventura, Barbara; You, Chang-Cheng; Hippius, Catharina; Würthner, Frank. In J. Phys. Chem. C., 111(2), pp. 622–630. 2007.
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  Photoinduced processes in a light-harvesting array PBI-NI4, made of a central perylene bisimide (PBI) with four appended naphthalene imide (NI) units, have been studied in toluene by several spectroscopic techniques, and the steps of energy dissipation have been identified. The singlet excited states 1PBI (λ max = 960 nm, ε = 40 000 M-1 cm-1) and 1NI (λ max = 810 nm, ε ca. 4 000 M-1 cm-1) and the charge-separated state PBI--NI4+ (λ max = 775 nm, ε = 80 000 M-1 cm-1) were identified as reaction intermediates. In the array PBI-NI4, energy transfer from the peripheral 1NI to the PBI core was shown to compete efficiently (90\%) with electron transfer from the NI unit to the PBI unit. Subsequently, 1PBI displays a slow electron abstraction (k = 4.6 × 108 s-1) from the NI unit to form the charge-separated state PBI--NI4+, which competes with emission of light energy from the PBI core. The CS state PBI--NI4+ decays faster (k = 2.6 × 109 s-1) than it is populated, preventing any back reaction to re-form the singlet excited state localized on PBI.

  @article{doi:10.1021/jp065394g, abstract = {Photoinduced processes in a light-harvesting array PBI-NI4, made of a central perylene bisimide (PBI) with four appended naphthalene imide (NI) units, have been studied in toluene by several spectroscopic techniques, and the steps of energy dissipation have been identified. The singlet excited states 1PBI (λ max = 960 nm, ε = 40 000 M-1 cm-1) and 1NI (λ max = 810 nm, ε ca. 4 000 M-1 cm-1) and the charge-separated state PBI–NI4+ (λ max = 775 nm, ε = 80 000 M-1 cm-1) were identified as reaction intermediates. In the array PBI-NI4, energy transfer from the peripheral 1NI to the PBI core was shown to compete efficiently (90\%) with electron transfer from the NI unit to the PBI unit. Subsequently, 1PBI displays a slow electron abstraction (k = 4.6 × 108 s-1) from the NI unit to form the charge-separated state PBI–NI4+, which competes with emission of light energy from the PBI core. The CS state PBI–NI4+ decays faster (k = 2.6 × 109 s-1) than it is populated, preventing any back reaction to re-form the singlet excited state localized on PBI.}, author = {Flamigni, Lucia and Ventura, Barbara and You, Chang-Cheng and Hippius, Catharina and Würthner, Frank}, journal = {J. Phys. Chem. C.}, keywords = {myown}, number = 2, pages = {622-630}, title = {Photophysical Characterization of a Light-Harvesting Tetra Naphthalene Imide/Perylene Bisimide Array}, volume = 111, year = 2007 }

  %0 Journal Article %1 doi:10.1021/jp065394g %A Flamigni, Lucia %A Ventura, Barbara %A You, Chang-Cheng %A Hippius, Catharina %A Würthner, Frank %D 2007 %J J. Phys. Chem. C. %N 2 %P 622-630 %R 10.1021/jp065394g %T Photophysical Characterization of a Light-Harvesting Tetra Naphthalene Imide/Perylene Bisimide Array %U http://dx.doi.org/10.1021/jp065394g %V 111 %X Photoinduced processes in a light-harvesting array PBI-NI4, made of a central perylene bisimide (PBI) with four appended naphthalene imide (NI) units, have been studied in toluene by several spectroscopic techniques, and the steps of energy dissipation have been identified. The singlet excited states 1PBI (λ max = 960 nm, ε = 40 000 M-1 cm-1) and 1NI (λ max = 810 nm, ε ca. 4 000 M-1 cm-1) and the charge-separated state PBI--NI4+ (λ max = 775 nm, ε = 80 000 M-1 cm-1) were identified as reaction intermediates. In the array PBI-NI4, energy transfer from the peripheral 1NI to the PBI core was shown to compete efficiently (90\%) with electron transfer from the NI unit to the PBI unit. Subsequently, 1PBI displays a slow electron abstraction (k = 4.6 × 108 s-1) from the NI unit to form the charge-separated state PBI--NI4+, which competes with emission of light energy from the PBI core. The CS state PBI--NI4+ decays faster (k = 2.6 × 109 s-1) than it is populated, preventing any back reaction to re-form the singlet excited state localized on PBI.
• Comparison of the Photophysical Parameters for Three Perylene Bisimide Derivatives by Single-Molecule Spectroscopy. Lang, Erwin; Hildner, Richard; Engelke, Hanna; Osswald, Peter; Würthner, Frank; Köhler, Jürgen. In ChemPhysChem, 8(10), pp. 1487–1496. 2007.
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  Characterization of the photophysical parameters for three perylene bisimide derivatives is presented. We exploited time-resolved and steady-state spectroscopy on both ensembles and single molecules under ambient as well as cryogenic (1.4 K) conditions. The finding is that these chromophores show extraordinary high fluorescence-emission rates, low intersystem crossing yields to the triplet state, and relatively short triplet lifetimes.

  @article{CPHC:CPHC200700186, abstract = {Characterization of the photophysical parameters for three perylene bisimide derivatives is presented. We exploited time-resolved and steady-state spectroscopy on both ensembles and single molecules under ambient as well as cryogenic (1.4 K) conditions. The finding is that these chromophores show extraordinary high fluorescence-emission rates, low intersystem crossing yields to the triplet state, and relatively short triplet lifetimes.}, author = {Lang, Erwin and Hildner, Richard and Engelke, Hanna and Osswald, Peter and Würthner, Frank and Köhler, Jürgen}, journal = {ChemPhysChem}, keywords = {myown}, number = 10, pages = {1487–1496}, publisher = {WILEY-VCH Verlag}, title = {Comparison of the Photophysical Parameters for Three Perylene Bisimide Derivatives by Single-Molecule Spectroscopy}, volume = 8, year = 2007 }

  %0 Journal Article %1 CPHC:CPHC200700186 %A Lang, Erwin %A Hildner, Richard %A Engelke, Hanna %A Osswald, Peter %A Würthner, Frank %A Köhler, Jürgen %D 2007 %I WILEY-VCH Verlag %J ChemPhysChem %N 10 %P 1487--1496 %R 10.1002/cphc.200700186 %T Comparison of the Photophysical Parameters for Three Perylene Bisimide Derivatives by Single-Molecule Spectroscopy %U http://dx.doi.org/10.1002/cphc.200700186 %V 8 %X Characterization of the photophysical parameters for three perylene bisimide derivatives is presented. We exploited time-resolved and steady-state spectroscopy on both ensembles and single molecules under ambient as well as cryogenic (1.4 K) conditions. The finding is that these chromophores show extraordinary high fluorescence-emission rates, low intersystem crossing yields to the triplet state, and relatively short triplet lifetimes.
• Circular dichroism and absorption spectroscopy of merocyanine dimer aggregates: molecular properties and exciton transfer dynamics from time-dependent quantum calculations. Seibt, Joachim; Lohr, Andreas; Würthner, Frank; Engel, Volker. In Phys. Chem. Chem. Phys., 9(47), pp. 6214–6218. 2007.
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  A wave packet approach to the calculation and interpretation of circular dichroism (CD) spectra is applied to the spectroscopy of aggregates of a merocyanine dye. A combined analysis of absorption and CD spectra allows for the extraction of geometric information and excited state electronic coupling. It is shown that in the case of dimer aggregates of a chiral merocyanine dye, it is possible to infer the dynamics of an exciton transfer directly from the CD spectrum. This relation is established via the Fourier relation to a time-dependent correlation function reflecting the quantum dynamics in the dye aggregate.

  @article{B712155E, abstract = {A wave packet approach to the calculation and interpretation of circular dichroism (CD) spectra is applied to the spectroscopy of aggregates of a merocyanine dye. A combined analysis of absorption and CD spectra allows for the extraction of geometric information and excited state electronic coupling. It is shown that in the case of dimer aggregates of a chiral merocyanine dye, it is possible to infer the dynamics of an exciton transfer directly from the CD spectrum. This relation is established via the Fourier relation to a time-dependent correlation function reflecting the quantum dynamics in the dye aggregate.}, author = {Seibt, Joachim and Lohr, Andreas and Würthner, Frank and Engel, Volker}, journal = {Phys. Chem. Chem. Phys.}, keywords = {myown}, number = 47, pages = {6214-6218}, publisher = {The Royal Society of Chemistry}, title = {Circular dichroism and absorption spectroscopy of merocyanine dimer aggregates: molecular properties and exciton transfer dynamics from time-dependent quantum calculations}, volume = 9, year = 2007 }

  %0 Journal Article %1 B712155E %A Seibt, Joachim %A Lohr, Andreas %A Würthner, Frank %A Engel, Volker %D 2007 %I The Royal Society of Chemistry %J Phys. Chem. Chem. Phys. %N 47 %P 6214-6218 %R 10.1039/B712155E %T Circular dichroism and absorption spectroscopy of merocyanine dimer aggregates: molecular properties and exciton transfer dynamics from time-dependent quantum calculations %U http://dx.doi.org/10.1039/B712155E %V 9 %X A wave packet approach to the calculation and interpretation of circular dichroism (CD) spectra is applied to the spectroscopy of aggregates of a merocyanine dye. A combined analysis of absorption and CD spectra allows for the extraction of geometric information and excited state electronic coupling. It is shown that in the case of dimer aggregates of a chiral merocyanine dye, it is possible to infer the dynamics of an exciton transfer directly from the CD spectrum. This relation is established via the Fourier relation to a time-dependent correlation function reflecting the quantum dynamics in the dye aggregate.
• Electroactive Polymeric Networks Created by Oxidation of Oligothiophene-Functionalized Perylene Bisimides. You, C.-C.; Espindola, P.; Hippius, C.; Heinze, J.; Würthner, F. In Advanced Functional Materials, 17(18), pp. 3764–3772. 2007.
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  A series of fourfold oligothienyl-functionalized perylene bisimides, N,N′-bis(2,6-diisopropylphenyl)-1,6,7,12-tetra(4-(7-[2,2′]bithien-5-yl)-heptanoyloxyphenoxy)perylene-3,4:9,10-tetracarboxylic acid bisimide (7a), N,N′-bis(2,6-diisopropylphenyl)-1,6,7,12-tetra(4-(7-[2,2′;5′,2′′]terthien-5-yl)-heptanoyloxyphenoxy)perylene-3,4:9,10-tetracarboxylic acid bisimide (7b), and N,N′-bis(2,6-diisopropylphenyl)-1,6,7,12-tetra(4-(7-(5″-Methyl-[2,2′;5′,2″]terthien-5-yl))-heptanoyloxyphenoxy)perylene-3,4:9,10-tetracarboxylic acid bisimide (7c), have been synthesized. Oligothienyl and perylene bisimide chromophores in these dyads display their characteristic optical UV/vis absorption properties. Upon excitation of the oligothiophene subunits, fluorescence resonance energy transfer (FRET) occurs to the perylene bisimide core. Cyclic voltammetric studies revealed that the reduction of the perylene bisimide moiety is not affected by the presence of oligothiophenes, showing two waves at around -0.7 and -1.0 V versus Ag/AgCl, respectively. On the other hand, the oxidation of the oligothienyl moieties leads to oxidative coupling for 7a and 7b, providing electroactive sexithiophene- and quaterthiophene-perylene bisimide networks, respectively. Electrochemical deposition of compounds 7a,b was performed and the films were characterized using cyclic voltammetry and in situ conductance, which reveal remarkable p-type conductivity. Significantly, two separate regimes of electrical conductance have been observed for the films generated from 7b.

  @article{ADFM:ADFM200700813, abstract = {A series of fourfold oligothienyl-functionalized perylene bisimides, N,N′-bis(2,6-diisopropylphenyl)-1,6,7,12-tetra(4-(7-[2,2′]bithien-5-yl)-heptanoyloxyphenoxy)perylene-3,4:9,10-tetracarboxylic acid bisimide (7a), N,N′-bis(2,6-diisopropylphenyl)-1,6,7,12-tetra(4-(7-[2,2′;5′,2′′]terthien-5-yl)-heptanoyloxyphenoxy)perylene-3,4:9,10-tetracarboxylic acid bisimide (7b), and N,N′-bis(2,6-diisopropylphenyl)-1,6,7,12-tetra(4-(7-(5″-Methyl-[2,2′;5′,2″]terthien-5-yl))-heptanoyloxyphenoxy)perylene-3,4:9,10-tetracarboxylic acid bisimide (7c), have been synthesized. Oligothienyl and perylene bisimide chromophores in these dyads display their characteristic optical UV/vis absorption properties. Upon excitation of the oligothiophene subunits, fluorescence resonance energy transfer (FRET) occurs to the perylene bisimide core. Cyclic voltammetric studies revealed that the reduction of the perylene bisimide moiety is not affected by the presence of oligothiophenes, showing two waves at around -0.7 and -1.0 V versus Ag/AgCl, respectively. On the other hand, the oxidation of the oligothienyl moieties leads to oxidative coupling for 7a and 7b, providing electroactive sexithiophene- and quaterthiophene-perylene bisimide networks, respectively. Electrochemical deposition of compounds 7a,b was performed and the films were characterized using cyclic voltammetry and in situ conductance, which reveal remarkable p-type conductivity. Significantly, two separate regimes of electrical conductance have been observed for the films generated from 7b.}, author = {You, C.-C. and Espindola, P. and Hippius, C. and Heinze, J. and Würthner, F.}, journal = {Advanced Functional Materials}, keywords = {myown}, number = 18, pages = {3764–3772}, publisher = {WILEY-VCH Verlag}, title = {Electroactive Polymeric Networks Created by Oxidation of Oligothiophene-Functionalized Perylene Bisimides}, volume = 17, year = 2007 }

  %0 Journal Article %1 ADFM:ADFM200700813 %A You, C.-C. %A Espindola, P. %A Hippius, C. %A Heinze, J. %A Würthner, F. %D 2007 %I WILEY-VCH Verlag %J Advanced Functional Materials %N 18 %P 3764--3772 %R 10.1002/adfm.200700813 %T Electroactive Polymeric Networks Created by Oxidation of Oligothiophene-Functionalized Perylene Bisimides %U http://dx.doi.org/10.1002/adfm.200700813 %V 17 %X A series of fourfold oligothienyl-functionalized perylene bisimides, N,N′-bis(2,6-diisopropylphenyl)-1,6,7,12-tetra(4-(7-[2,2′]bithien-5-yl)-heptanoyloxyphenoxy)perylene-3,4:9,10-tetracarboxylic acid bisimide (7a), N,N′-bis(2,6-diisopropylphenyl)-1,6,7,12-tetra(4-(7-[2,2′;5′,2′′]terthien-5-yl)-heptanoyloxyphenoxy)perylene-3,4:9,10-tetracarboxylic acid bisimide (7b), and N,N′-bis(2,6-diisopropylphenyl)-1,6,7,12-tetra(4-(7-(5″-Methyl-[2,2′;5′,2″]terthien-5-yl))-heptanoyloxyphenoxy)perylene-3,4:9,10-tetracarboxylic acid bisimide (7c), have been synthesized. Oligothienyl and perylene bisimide chromophores in these dyads display their characteristic optical UV/vis absorption properties. Upon excitation of the oligothiophene subunits, fluorescence resonance energy transfer (FRET) occurs to the perylene bisimide core. Cyclic voltammetric studies revealed that the reduction of the perylene bisimide moiety is not affected by the presence of oligothiophenes, showing two waves at around -0.7 and -1.0 V versus Ag/AgCl, respectively. On the other hand, the oxidation of the oligothienyl moieties leads to oxidative coupling for 7a and 7b, providing electroactive sexithiophene- and quaterthiophene-perylene bisimide networks, respectively. Electrochemical deposition of compounds 7a,b was performed and the films were characterized using cyclic voltammetry and in situ conductance, which reveal remarkable p-type conductivity. Significantly, two separate regimes of electrical conductance have been observed for the films generated from 7b.
• Self-Assembly of Semifluorinated Minidendrons Attached to Electron-Acceptor Groups into Pyramidal Columns. Percec, Virgil; Aqad, Emad; Peterca, Mihai; Imam, Mohammad R.; Glodde, Martin; Bera, Tusha K.; Miura, Yoshiko; Balagurusamy, Venkatachalapathy S. K.; Ewbank, Paul C.; Würthner, Frank; Heiney, Paul A. In Chemistry – A European Journal, 13(12), pp. 3330–3345. 2007.
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  The synthesis and self-assembly of twelve semifluorinated first-generation dendrons or minidendrons attached to electron-acceptor (n-type) groups generated from various combinations of eight acceptors and three dendrons are reported. Dendrons attached to small electron-acceptor molecules mediate their self-assembly into π-stacks located in the center of a supramolecular helical pyramidal column with the long axis of the acceptor perpendicular to the long axis of the column. Dendrons attached to large electron-acceptor molecules, such as perylene bisimide, mediate the assembly of their acceptors in an unprecedented arrangement of π-stacks that have the long axis of the acceptors parallel to the long axis of the supramolecular pyramidal column. All supramolecular columns self-organize into various periodic columnar arrays that exhibit liquid-crystalline phases, crystalline phases, or a liquid-crystalline phase with enhanced intracolumnar order. The present study demonstrates the simplicity and the versatility of the concept of assembly of n-type electroactive groups mediated by semifluorinated dendrons and assesses the scope and limitations of this supramolecular strategy.

  @article{CHEM:CHEM200600901, abstract = {The synthesis and self-assembly of twelve semifluorinated first-generation dendrons or minidendrons attached to electron-acceptor (n-type) groups generated from various combinations of eight acceptors and three dendrons are reported. Dendrons attached to small electron-acceptor molecules mediate their self-assembly into π-stacks located in the center of a supramolecular helical pyramidal column with the long axis of the acceptor perpendicular to the long axis of the column. Dendrons attached to large electron-acceptor molecules, such as perylene bisimide, mediate the assembly of their acceptors in an unprecedented arrangement of π-stacks that have the long axis of the acceptors parallel to the long axis of the supramolecular pyramidal column. All supramolecular columns self-organize into various periodic columnar arrays that exhibit liquid-crystalline phases, crystalline phases, or a liquid-crystalline phase with enhanced intracolumnar order. The present study demonstrates the simplicity and the versatility of the concept of assembly of n-type electroactive groups mediated by semifluorinated dendrons and assesses the scope and limitations of this supramolecular strategy.}, author = {Percec, Virgil and Aqad, Emad and Peterca, Mihai and Imam, Mohammad R. and Glodde, Martin and Bera, Tusha K. and Miura, Yoshiko and Balagurusamy, Venkatachalapathy S. K. and Ewbank, Paul C. and Würthner, Frank and Heiney, Paul A.}, journal = {Chemistry – A European Journal}, keywords = {myown}, number = 12, pages = {3330–3345}, publisher = {WILEY-VCH Verlag}, title = {Self-Assembly of Semifluorinated Minidendrons Attached to Electron-Acceptor Groups into Pyramidal Columns}, volume = 13, year = 2007 }

  %0 Journal Article %1 CHEM:CHEM200600901 %A Percec, Virgil %A Aqad, Emad %A Peterca, Mihai %A Imam, Mohammad R. %A Glodde, Martin %A Bera, Tusha K. %A Miura, Yoshiko %A Balagurusamy, Venkatachalapathy S. K. %A Ewbank, Paul C. %A Würthner, Frank %A Heiney, Paul A. %D 2007 %I WILEY-VCH Verlag %J Chemistry – A European Journal %N 12 %P 3330--3345 %R 10.1002/chem.200600901 %T Self-Assembly of Semifluorinated Minidendrons Attached to Electron-Acceptor Groups into Pyramidal Columns %U http://dx.doi.org/10.1002/chem.200600901 %V 13 %X The synthesis and self-assembly of twelve semifluorinated first-generation dendrons or minidendrons attached to electron-acceptor (n-type) groups generated from various combinations of eight acceptors and three dendrons are reported. Dendrons attached to small electron-acceptor molecules mediate their self-assembly into π-stacks located in the center of a supramolecular helical pyramidal column with the long axis of the acceptor perpendicular to the long axis of the column. Dendrons attached to large electron-acceptor molecules, such as perylene bisimide, mediate the assembly of their acceptors in an unprecedented arrangement of π-stacks that have the long axis of the acceptors parallel to the long axis of the supramolecular pyramidal column. All supramolecular columns self-organize into various periodic columnar arrays that exhibit liquid-crystalline phases, crystalline phases, or a liquid-crystalline phase with enhanced intracolumnar order. The present study demonstrates the simplicity and the versatility of the concept of assembly of n-type electroactive groups mediated by semifluorinated dendrons and assesses the scope and limitations of this supramolecular strategy.
• Synthesis of Merocyanine Dye Nanorods: The Importance of Solvent, Kinetic and Thermodynamic Control, and Steric Effects on Self-Assembly. Lohr, Andreas; Gress, Tobias; Deppisch, Manuela; Knoll, Marina; Würthner, Frank. 2007.
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  Aggregation of dipolar merocyanine dyes into antiparallel dimers with high binding constant is an interesting binding motif for the construction of functional supramolecular architectures. This dipolar aggregation has been utilized for the formation of well-defined cylindrical nanorods. The self-assembly of these nanorods is profoundly influenced by solvent polarity which determines nanorod growth under kinetic or thermodynamic control. A newly synthesized series of bis(merocyanine) dyes bearing alkyl substituents of different chain lengths and branching further reveals that small structural changes of the monomeric building blocks have a considerable impact on the stability and structure of the aggregates. The knowledge acquired by the present study should be helpful for the development of self-assembled nanomaterials.

  @article{lohr2007synthesis, abstract = {Aggregation of dipolar merocyanine dyes into antiparallel dimers with high binding constant is an interesting binding motif for the construction of functional supramolecular architectures. This dipolar aggregation has been utilized for the formation of well-defined cylindrical nanorods. The self-assembly of these nanorods is profoundly influenced by solvent polarity which determines nanorod growth under kinetic or thermodynamic control. A newly synthesized series of bis(merocyanine) dyes bearing alkyl substituents of different chain lengths and branching further reveals that small structural changes of the monomeric building blocks have a considerable impact on the stability and structure of the aggregates. The knowledge acquired by the present study should be helpful for the development of self-assembled nanomaterials.}, author = {Lohr, Andreas and Gress, Tobias and Deppisch, Manuela and Knoll, Marina and Würthner, Frank}, keywords = {myown}, title = {Synthesis of Merocyanine Dye Nanorods: The Importance of Solvent, Kinetic and Thermodynamic Control, and Steric Effects on Self-Assembly}, year = 2007 }

  %0 Journal Article %1 lohr2007synthesis %A Lohr, Andreas %A Gress, Tobias %A Deppisch, Manuela %A Knoll, Marina %A Würthner, Frank %D 2007 %R 10.1055/s-2007-983900 %T Synthesis of Merocyanine Dye Nanorods: The Importance of Solvent, Kinetic and Thermodynamic Control, and Steric Effects on Self-Assembly %U https://www.thieme-connect.de/DOI/DOI?10.1055/s-2007-983900 %X Aggregation of dipolar merocyanine dyes into antiparallel dimers with high binding constant is an interesting binding motif for the construction of functional supramolecular architectures. This dipolar aggregation has been utilized for the formation of well-defined cylindrical nanorods. The self-assembly of these nanorods is profoundly influenced by solvent polarity which determines nanorod growth under kinetic or thermodynamic control. A newly synthesized series of bis(merocyanine) dyes bearing alkyl substituents of different chain lengths and branching further reveals that small structural changes of the monomeric building blocks have a considerable impact on the stability and structure of the aggregates. The knowledge acquired by the present study should be helpful for the development of self-assembled nanomaterials.
• Core-Tetrasubstituted Naphthalene Diimides:  Synthesis, Optical Properties, and Redox Characteristics. Röger, Cornelia; Würthner, Frank. In The Journal of Organic Chemistry, 72(21), pp. 8070–8075. 2007.

  PMID: 17887710
  • [ Abstract ]
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  2,3,6,7-Tetrabromonaphthalene dianhydride has been synthesized by the bromination of naphthalene dianhydride with dibromoisocyanuric acid in excellent yield. The condensation of this dianhydride with 2,6-diisopropylaniline yielded the corresponding tetrabromo-substituted naphthalene diimide (NDI), which is a versatile precursor for the synthesis of core-tetrafunctionalized NDIs. Nucleophilic substitution of tetrabromo NDI with alkoxy, alkylthio, and alkylamino nucleophiles afforded a series of core-tetrasubstituted NDI chromophores that complete the series of previously reported di- and trifunctionalized NDI derivatives. The effects of electronic nature and number of core substituents on the optical and electrochemical properties of NDIs have been investigated by UV−vis and fluorescence spectroscopy and cyclic voltammetry. The absorption maxima (629−642 nm) of tetraamino NDIs are strongly bathochromically shifted compared to those of other core-functionalized NDIs.

  @article{doi:10.1021/jo7015357, abstract = {2,3,6,7-Tetrabromonaphthalene dianhydride has been synthesized by the bromination of naphthalene dianhydride with dibromoisocyanuric acid in excellent yield. The condensation of this dianhydride with 2,6-diisopropylaniline yielded the corresponding tetrabromo-substituted naphthalene diimide (NDI), which is a versatile precursor for the synthesis of core-tetrafunctionalized NDIs. Nucleophilic substitution of tetrabromo NDI with alkoxy, alkylthio, and alkylamino nucleophiles afforded a series of core-tetrasubstituted NDI chromophores that complete the series of previously reported di- and trifunctionalized NDI derivatives. The effects of electronic nature and number of core substituents on the optical and electrochemical properties of NDIs have been investigated by UV−vis and fluorescence spectroscopy and cyclic voltammetry. The absorption maxima (629−642 nm) of tetraamino NDIs are strongly bathochromically shifted compared to those of other core-functionalized NDIs.}, author = {Röger, Cornelia and Würthner, Frank}, journal = {The Journal of Organic Chemistry}, keywords = {myown}, note = {PMID: 17887710}, number = 21, pages = {8070-8075}, title = {Core-Tetrasubstituted Naphthalene Diimides:  Synthesis, Optical Properties, and Redox Characteristics}, volume = 72, year = 2007 }

  %0 Journal Article %1 doi:10.1021/jo7015357 %A Röger, Cornelia %A Würthner, Frank %D 2007 %J The Journal of Organic Chemistry %N 21 %P 8070-8075 %R 10.1021/jo7015357 %T Core-Tetrasubstituted Naphthalene Diimides:  Synthesis, Optical Properties, and Redox Characteristics %U http://dx.doi.org/10.1021/jo7015357 %V 72 %X 2,3,6,7-Tetrabromonaphthalene dianhydride has been synthesized by the bromination of naphthalene dianhydride with dibromoisocyanuric acid in excellent yield. The condensation of this dianhydride with 2,6-diisopropylaniline yielded the corresponding tetrabromo-substituted naphthalene diimide (NDI), which is a versatile precursor for the synthesis of core-tetrafunctionalized NDIs. Nucleophilic substitution of tetrabromo NDI with alkoxy, alkylthio, and alkylamino nucleophiles afforded a series of core-tetrasubstituted NDI chromophores that complete the series of previously reported di- and trifunctionalized NDI derivatives. The effects of electronic nature and number of core substituents on the optical and electrochemical properties of NDIs have been investigated by UV−vis and fluorescence spectroscopy and cyclic voltammetry. The absorption maxima (629−642 nm) of tetraamino NDIs are strongly bathochromically shifted compared to those of other core-functionalized NDIs.
• Core-Fluorinated Perylene Bisimide Dyes: Air Stable n-Channel Organic Semiconductors for Thin Film Transistors with Exceptionally High On-to-Off Current Ratios. Schmidt, R.; Ling, M. M.; Oh, J. H.; Winkler, M.; Könemann, M.; Bao, Z.; Würthner, F. In Advanced Materials, 19(21), pp. 3692–3695. 2007.
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  @article{ADMA:ADMA200701478, author = {Schmidt, R. and Ling, M. M. and Oh, J. H. and Winkler, M. and Könemann, M. and Bao, Z. and Würthner, F.}, journal = {Advanced Materials}, keywords = {myown}, number = 21, pages = {3692–3695}, publisher = {WILEY-VCH Verlag}, title = {Core-Fluorinated Perylene Bisimide Dyes: Air Stable n-Channel Organic Semiconductors for Thin Film Transistors with Exceptionally High On-to-Off Current Ratios}, volume = 19, year = 2007 }

  %0 Journal Article %1 ADMA:ADMA200701478 %A Schmidt, R. %A Ling, M. M. %A Oh, J. H. %A Winkler, M. %A Könemann, M. %A Bao, Z. %A Würthner, F. %D 2007 %I WILEY-VCH Verlag %J Advanced Materials %N 21 %P 3692--3695 %R 10.1002/adma.200701478 %T Core-Fluorinated Perylene Bisimide Dyes: Air Stable n-Channel Organic Semiconductors for Thin Film Transistors with Exceptionally High On-to-Off Current Ratios %U http://dx.doi.org/10.1002/adma.200701478 %V 19
• Air-stable n-channel organic thin-film transistors with high field-effect mobility based on N,N′-bis(heptafluorobutyl)-3,4:9,10-perylene diimide. Oh, Joon Hak; Liu, Shuhong; Bao, Zhenan; Schmidt, Rüdiger; Würthner, Frank. In Applied Physics Letters, 91(21), p. 212107. 2007.
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  @article{doi:10.1063/1.2803073, author = {Oh, Joon Hak and Liu, Shuhong and Bao, Zhenan and Schmidt, Rüdiger and Würthner, Frank}, journal = {Applied Physics Letters}, keywords = {myown}, number = 21, pages = 212107, title = {Air-stable n-channel organic thin-film transistors with high field-effect mobility based on N,N′-bis(heptafluorobutyl)-3,4:9,10-perylene diimide}, volume = 91, year = 2007 }

  %0 Journal Article %1 doi:10.1063/1.2803073 %A Oh, Joon Hak %A Liu, Shuhong %A Bao, Zhenan %A Schmidt, Rüdiger %A Würthner, Frank %D 2007 %J Applied Physics Letters %N 21 %P 212107 %R 10.1063/1.2803073 %T Air-stable n-channel organic thin-film transistors with high field-effect mobility based on N,N′-bis(heptafluorobutyl)-3,4:9,10-perylene diimide %U https://doi.org/10.1063/1.2803073 %V 91
• Conformational Effects of Bay Substituents on Optical, Electrochemical and Dynamic Properties of Perylene Bisimides: Macrocyclic Derivatives as Effective Probes. Osswald, Peter; Würthner, Frank. In Chemistry – A European Journal, 13(26), pp. 7395–7409. 2007.
  • [ Abstract ]
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  A series of diagonally and laterally bridged regioisomeric macrocycles based on 1,6,7,12-tetraaryloxy-substituted perylene bisimides (APBIs) have been synthesized and characterized. The different orientations of the aryloxy residues, that is, horizontal or perpendicular to the perylene core, in the regioisomeric macrocycles have been elucidated by NMR spectroscopy, and the dynamic properties of the laterally bridged regioisomers have been investigated by temperature-dependent NMR measurements. The influence of the different orientations of the aryloxy substituents on the electrochemical properties of APBIs is demonstrated by cyclic voltammetry, which reveals that a perpendicular orientation of the aryloxy residues relative to the perylene core leads to a substantial decrease of the LUMO energy level of the perylene bisimide electrophore. The optical properties of the regioisomeric macrocycles have been determined by UV/Vis and fluorescence spectroscopy. It has been shown that the diagonally bridged macrocycles exhibit optical properties that differ significantly from those of an open-chain reference compound, whereas the optical properties of the laterally bridged isomers resemble those of the reference system. This demonstrates that unrestricted aryloxy substituents prefer the lateral conformation in solution. Solvent-dependent fluorescent properties have been exemplified for one diagonally bridged derivative, suggesting a photoinduced electron transfer process as fluorescence quenching mechanism for APBIs. From these investigations, guidelines toward highly fluorescent APBI dyes in polar media could be derived.

  @article{CHEM:CHEM200700601, abstract = {A series of diagonally and laterally bridged regioisomeric macrocycles based on 1,6,7,12-tetraaryloxy-substituted perylene bisimides (APBIs) have been synthesized and characterized. The different orientations of the aryloxy residues, that is, horizontal or perpendicular to the perylene core, in the regioisomeric macrocycles have been elucidated by NMR spectroscopy, and the dynamic properties of the laterally bridged regioisomers have been investigated by temperature-dependent NMR measurements. The influence of the different orientations of the aryloxy substituents on the electrochemical properties of APBIs is demonstrated by cyclic voltammetry, which reveals that a perpendicular orientation of the aryloxy residues relative to the perylene core leads to a substantial decrease of the LUMO energy level of the perylene bisimide electrophore. The optical properties of the regioisomeric macrocycles have been determined by UV/Vis and fluorescence spectroscopy. It has been shown that the diagonally bridged macrocycles exhibit optical properties that differ significantly from those of an open-chain reference compound, whereas the optical properties of the laterally bridged isomers resemble those of the reference system. This demonstrates that unrestricted aryloxy substituents prefer the lateral conformation in solution. Solvent-dependent fluorescent properties have been exemplified for one diagonally bridged derivative, suggesting a photoinduced electron transfer process as fluorescence quenching mechanism for APBIs. From these investigations, guidelines toward highly fluorescent APBI dyes in polar media could be derived.}, author = {Osswald, Peter and Würthner, Frank}, journal = {Chemistry – A European Journal}, keywords = {myown}, number = 26, pages = {7395–7409}, publisher = {WILEY-VCH Verlag}, title = {Conformational Effects of Bay Substituents on Optical, Electrochemical and Dynamic Properties of Perylene Bisimides: Macrocyclic Derivatives as Effective Probes}, volume = 13, year = 2007 }

  %0 Journal Article %1 CHEM:CHEM200700601 %A Osswald, Peter %A Würthner, Frank %D 2007 %I WILEY-VCH Verlag %J Chemistry – A European Journal %N 26 %P 7395--7409 %R 10.1002/chem.200700601 %T Conformational Effects of Bay Substituents on Optical, Electrochemical and Dynamic Properties of Perylene Bisimides: Macrocyclic Derivatives as Effective Probes %U http://dx.doi.org/10.1002/chem.200700601 %V 13 %X A series of diagonally and laterally bridged regioisomeric macrocycles based on 1,6,7,12-tetraaryloxy-substituted perylene bisimides (APBIs) have been synthesized and characterized. The different orientations of the aryloxy residues, that is, horizontal or perpendicular to the perylene core, in the regioisomeric macrocycles have been elucidated by NMR spectroscopy, and the dynamic properties of the laterally bridged regioisomers have been investigated by temperature-dependent NMR measurements. The influence of the different orientations of the aryloxy substituents on the electrochemical properties of APBIs is demonstrated by cyclic voltammetry, which reveals that a perpendicular orientation of the aryloxy residues relative to the perylene core leads to a substantial decrease of the LUMO energy level of the perylene bisimide electrophore. The optical properties of the regioisomeric macrocycles have been determined by UV/Vis and fluorescence spectroscopy. It has been shown that the diagonally bridged macrocycles exhibit optical properties that differ significantly from those of an open-chain reference compound, whereas the optical properties of the laterally bridged isomers resemble those of the reference system. This demonstrates that unrestricted aryloxy substituents prefer the lateral conformation in solution. Solvent-dependent fluorescent properties have been exemplified for one diagonally bridged derivative, suggesting a photoinduced electron transfer process as fluorescence quenching mechanism for APBIs. From these investigations, guidelines toward highly fluorescent APBI dyes in polar media could be derived.
• Absorption spectroscopy of molecular trimers. Seibt, Joachim; Dehm, Volker; Würthner, Frank; Engel, Volker. In The Journal of Chemical Physics, 126(16), p. 164308. 2007.
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  @article{doi:10.1063/1.2721540, author = {Seibt, Joachim and Dehm, Volker and Würthner, Frank and Engel, Volker}, journal = {The Journal of Chemical Physics}, keywords = {myown}, number = 16, pages = 164308, title = {Absorption spectroscopy of molecular trimers}, volume = 126, year = 2007 }

  %0 Journal Article %1 doi:10.1063/1.2721540 %A Seibt, Joachim %A Dehm, Volker %A Würthner, Frank %A Engel, Volker %D 2007 %J The Journal of Chemical Physics %N 16 %P 164308 %R 10.1063/1.2721540 %T Absorption spectroscopy of molecular trimers %U https://doi.org/10.1063/1.2721540 %V 126
• Perylene Bisimide Atropisomers:  Synthesis, Resolution, and Stereochemical Assignment. Osswald, Peter; Reichert, Matthias; Bringmann, Gerhard; Würthner, Frank. In The Journal of Organic Chemistry, 72(9), pp. 3403–3411. 2007.

  PMID: 17388634
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  The macrocyclization of the tetra-hydroxyphenoxy-substituted perylene bisimide 4 bearing two (R)-configured 2-octyl substituents in the imide positions by etherification with diethylene glycol ditosylate afforded both the diagonally bridged (1,7- and 6,12-linkage) and laterally bridged (1,12- and 6,7-linkage) regioisomers 6 and 7. The atropo-diastereomers of the diagonally bridged macrocycle 6 were separated by semipreparative HPLC on a chiral column, and their absolute configurations were determined by circular dichroism (CD) spectroscopy in combination with quantum chemical CD calculations. The isolated epimers (P,R,R)-6 and (M,R,R)-6 represent the first examples of diasteriomerically pure perylene bisimide atropisomers. The optical and chiroptical properties of these epimers were investigated by UV/vis, fluorescence, and CD spectroscopy, and their conformational properties have been explored by temperature-dependent 1H NMR studies.

  @article{doi:10.1021/jo070056c, abstract = {The macrocyclization of the tetra-hydroxyphenoxy-substituted perylene bisimide 4 bearing two (R)-configured 2-octyl substituents in the imide positions by etherification with diethylene glycol ditosylate afforded both the diagonally bridged (1,7- and 6,12-linkage) and laterally bridged (1,12- and 6,7-linkage) regioisomers 6 and 7. The atropo-diastereomers of the diagonally bridged macrocycle 6 were separated by semipreparative HPLC on a chiral column, and their absolute configurations were determined by circular dichroism (CD) spectroscopy in combination with quantum chemical CD calculations. The isolated epimers (P,R,R)-6 and (M,R,R)-6 represent the first examples of diasteriomerically pure perylene bisimide atropisomers. The optical and chiroptical properties of these epimers were investigated by UV/vis, fluorescence, and CD spectroscopy, and their conformational properties have been explored by temperature-dependent 1H NMR studies.}, author = {Osswald, Peter and Reichert, Matthias and Bringmann, Gerhard and Würthner, Frank}, journal = {The Journal of Organic Chemistry}, keywords = {myown}, note = {PMID: 17388634}, number = 9, pages = {3403-3411}, title = {Perylene Bisimide Atropisomers:  Synthesis, Resolution, and Stereochemical Assignment}, volume = 72, year = 2007 }

  %0 Journal Article %1 doi:10.1021/jo070056c %A Osswald, Peter %A Reichert, Matthias %A Bringmann, Gerhard %A Würthner, Frank %D 2007 %J The Journal of Organic Chemistry %N 9 %P 3403-3411 %R 10.1021/jo070056c %T Perylene Bisimide Atropisomers:  Synthesis, Resolution, and Stereochemical Assignment %U http://dx.doi.org/10.1021/jo070056c %V 72 %X The macrocyclization of the tetra-hydroxyphenoxy-substituted perylene bisimide 4 bearing two (R)-configured 2-octyl substituents in the imide positions by etherification with diethylene glycol ditosylate afforded both the diagonally bridged (1,7- and 6,12-linkage) and laterally bridged (1,12- and 6,7-linkage) regioisomers 6 and 7. The atropo-diastereomers of the diagonally bridged macrocycle 6 were separated by semipreparative HPLC on a chiral column, and their absolute configurations were determined by circular dichroism (CD) spectroscopy in combination with quantum chemical CD calculations. The isolated epimers (P,R,R)-6 and (M,R,R)-6 represent the first examples of diasteriomerically pure perylene bisimide atropisomers. The optical and chiroptical properties of these epimers were investigated by UV/vis, fluorescence, and CD spectroscopy, and their conformational properties have been explored by temperature-dependent 1H NMR studies.
• Morphology Control of Fluorescent Nanoaggregates by Co-Self-Assembly of Wedge- and Dumbbell-Shaped Amphiphilic Perylene Bisimides. Zhang, Xin; Chen, Zhijian; Würthner, Frank. In J. Am. Chem. Soc., 129(16), pp. 4886–4887. 2007.

  PMID: 17402739
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  Wedge- and dumbbell-shaped amphiphilic perylene bisimides PBI 1−4 were synthesized. The wedge-shaped PBI 1 and PBI 2 and dumbbell-shaped PBI 4 self-assemble into micelles, and rod aggregates in aqueous solution, respectively. Interestingly, the co-self-assembly of wedge-shaped PBI 1 with dumbbell-shaped PBI 3 generates hollow vesicles with bilayer structures because of the curvature changes during the self-assembly process. The bilayer vesicles could be stabilized by in situ photopolymerization.

  @article{doi:10.1021/ja070994u, abstract = {Wedge- and dumbbell-shaped amphiphilic perylene bisimides PBI 1−4 were synthesized. The wedge-shaped PBI 1 and PBI 2 and dumbbell-shaped PBI 4 self-assemble into micelles, and rod aggregates in aqueous solution, respectively. Interestingly, the co-self-assembly of wedge-shaped PBI 1 with dumbbell-shaped PBI 3 generates hollow vesicles with bilayer structures because of the curvature changes during the self-assembly process. The bilayer vesicles could be stabilized by in situ photopolymerization.}, author = {Zhang, Xin and Chen, Zhijian and Würthner, Frank}, journal = {J. Am. Chem. Soc.}, keywords = {myown}, note = {PMID: 17402739}, number = 16, pages = {4886-4887}, title = {Morphology Control of Fluorescent Nanoaggregates by Co-Self-Assembly of Wedge- and Dumbbell-Shaped Amphiphilic Perylene Bisimides}, volume = 129, year = 2007 }

  %0 Journal Article %1 doi:10.1021/ja070994u %A Zhang, Xin %A Chen, Zhijian %A Würthner, Frank %D 2007 %J J. Am. Chem. Soc. %N 16 %P 4886-4887 %R 10.1021/ja070994u %T Morphology Control of Fluorescent Nanoaggregates by Co-Self-Assembly of Wedge- and Dumbbell-Shaped Amphiphilic Perylene Bisimides %U http://dx.doi.org/10.1021/ja070994u %V 129 %X Wedge- and dumbbell-shaped amphiphilic perylene bisimides PBI 1−4 were synthesized. The wedge-shaped PBI 1 and PBI 2 and dumbbell-shaped PBI 4 self-assemble into micelles, and rod aggregates in aqueous solution, respectively. Interestingly, the co-self-assembly of wedge-shaped PBI 1 with dumbbell-shaped PBI 3 generates hollow vesicles with bilayer structures because of the curvature changes during the self-assembly process. The bilayer vesicles could be stabilized by in situ photopolymerization.
• Photoluminescence and Conductivity of Self-Assembled π–π Stacks of Perylene Bisimide Dyes. Chen, Zhijian; Stepanenko, Vladimir; Dehm, Volker; Prins, Paulette; Siebbeles, Laurens D. A.; Seibt, Joachim; Marquetand, Philipp; Engel, Volker; Würthner, Frank. In Chemistry – A European Journal, 13(2), pp. 436–449. 2007.
  • [ Abstract ]
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  The self-assembly of a new, highly fluorescent perylene bisimide dye 2 into π stacks, both in solution and condensed phase, has been studied in detail by NMR spectroscopy, vapor pressure osmometry (VPO), UV/Vis and fluorescence spectroscopy, differential scanning calorimetry (DSC), optical polarizing microscopy (OPM) and X-ray diffraction. The NMR and VPO measurements revealed the formation of extended π–π stacks of the dye molecules in solution. The aggregate size determined from VPO and DOSY NMR measurements agree well with that obtained from the concentration and temperature-dependent UV/Vis spectral data by employing the isodesmic model (equal K model). In the condensed state, dye 2 possesses a hexagonal columnar liquid crystalline (LC) phase as confirmed by X-ray diffraction analysis. The columnar stacking of this dye has been further explored by atomic force microscopy (AFM). Well-resolved columnar nanostructures of the compound are observed on graphite surface. A color-tunable luminescence from green to red has been observed upon aggregation which is accompanied by an increase of the fluorescence lifetime and depolarization. The observed absorption properties can be explained in terms of molecular exciton theory. The charge transport properties of dye 2 have been investigated by pulse radiolysis-time resolved microwave conductivity measurements and a 1D charge carrier mobility up to 0.42 cm2 V−1 s−1 is obtained. Considering the promising self-assembly, semiconducting, and luminescence properties of this dye, it might serve as a useful functional material for nano(opto)electronics.

  @article{CHEM:CHEM200600889, abstract = {The self-assembly of a new, highly fluorescent perylene bisimide dye 2 into π stacks, both in solution and condensed phase, has been studied in detail by NMR spectroscopy, vapor pressure osmometry (VPO), UV/Vis and fluorescence spectroscopy, differential scanning calorimetry (DSC), optical polarizing microscopy (OPM) and X-ray diffraction. The NMR and VPO measurements revealed the formation of extended π–π stacks of the dye molecules in solution. The aggregate size determined from VPO and DOSY NMR measurements agree well with that obtained from the concentration and temperature-dependent UV/Vis spectral data by employing the isodesmic model (equal K model). In the condensed state, dye 2 possesses a hexagonal columnar liquid crystalline (LC) phase as confirmed by X-ray diffraction analysis. The columnar stacking of this dye has been further explored by atomic force microscopy (AFM). Well-resolved columnar nanostructures of the compound are observed on graphite surface. A color-tunable luminescence from green to red has been observed upon aggregation which is accompanied by an increase of the fluorescence lifetime and depolarization. The observed absorption properties can be explained in terms of molecular exciton theory. The charge transport properties of dye 2 have been investigated by pulse radiolysis-time resolved microwave conductivity measurements and a 1D charge carrier mobility up to 0.42 cm2 V−1 s−1 is obtained. Considering the promising self-assembly, semiconducting, and luminescence properties of this dye, it might serve as a useful functional material for nano(opto)electronics.}, author = {Chen, Zhijian and Stepanenko, Vladimir and Dehm, Volker and Prins, Paulette and Siebbeles, Laurens D. A. and Seibt, Joachim and Marquetand, Philipp and Engel, Volker and Würthner, Frank}, journal = {Chemistry – A European Journal}, keywords = {myown}, number = 2, pages = {436–449}, publisher = {WILEY-VCH Verlag}, title = {Photoluminescence and Conductivity of Self-Assembled π–π Stacks of Perylene Bisimide Dyes}, volume = 13, year = 2007 }

  %0 Journal Article %1 CHEM:CHEM200600889 %A Chen, Zhijian %A Stepanenko, Vladimir %A Dehm, Volker %A Prins, Paulette %A Siebbeles, Laurens D. A. %A Seibt, Joachim %A Marquetand, Philipp %A Engel, Volker %A Würthner, Frank %D 2007 %I WILEY-VCH Verlag %J Chemistry – A European Journal %N 2 %P 436--449 %R 10.1002/chem.200600889 %T Photoluminescence and Conductivity of Self-Assembled π–π Stacks of Perylene Bisimide Dyes %U http://dx.doi.org/10.1002/chem.200600889 %V 13 %X The self-assembly of a new, highly fluorescent perylene bisimide dye 2 into π stacks, both in solution and condensed phase, has been studied in detail by NMR spectroscopy, vapor pressure osmometry (VPO), UV/Vis and fluorescence spectroscopy, differential scanning calorimetry (DSC), optical polarizing microscopy (OPM) and X-ray diffraction. The NMR and VPO measurements revealed the formation of extended π–π stacks of the dye molecules in solution. The aggregate size determined from VPO and DOSY NMR measurements agree well with that obtained from the concentration and temperature-dependent UV/Vis spectral data by employing the isodesmic model (equal K model). In the condensed state, dye 2 possesses a hexagonal columnar liquid crystalline (LC) phase as confirmed by X-ray diffraction analysis. The columnar stacking of this dye has been further explored by atomic force microscopy (AFM). Well-resolved columnar nanostructures of the compound are observed on graphite surface. A color-tunable luminescence from green to red has been observed upon aggregation which is accompanied by an increase of the fluorescence lifetime and depolarization. The observed absorption properties can be explained in terms of molecular exciton theory. The charge transport properties of dye 2 have been investigated by pulse radiolysis-time resolved microwave conductivity measurements and a 1D charge carrier mobility up to 0.42 cm2 V−1 s−1 is obtained. Considering the promising self-assembly, semiconducting, and luminescence properties of this dye, it might serve as a useful functional material for nano(opto)electronics.
• Effect of Core Twisting on Self-Assembly and Optical Properties of Perylene Bisimide Dyes in Solution and Columnar Liquid Crystalline Phases. Chen, Zhijian; Baumeister, Ute; Tschierske, Carsten; Würthner, Frank. In Chemistry – A European Journal, 13(2), pp. 450–465. 2007.
  • [ Abstract ]
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  A series of highly soluble and fluorescent core-twisted perylene bisimide dyes (PBIs) 3 a–f with different substituents at the bay area (1,6,7,12 positions of the perylene core) were synthesized and fully characterized by 1H NMR, UV/Vis spectroscopy, MS spectrometry, and elemental analysis. The π–π aggregation properties of these new functional dyes were investigated in detail both in solution and in condensed phase by UV/Vis and fluorescence spectroscopy, vapor pressure osmometry (VPO), differential scanning calorimetry (DSC), polarizing optical microscopy (POM), and X-ray diffraction. Concentration-dependent UV/Vis measurements and VPO analysis revealed that these core-twisted π-conjugated systems show distinct self-dimerization equilibria in apolar solvent methylcyclohexane (MCH) with dimerization constants between 1.3×104 and 30 M−1. The photoluminescence spectra of the dimers of PBIs 3 a–f exhibit bathochromic shifts of quite different magnitude which could be attributed to different longitudinal or rotational offsets between the dyes as well as differences in the respective π–π stacking distance. In condensed state, quite a few of these PBIs form luminescent rectangular or hexagonal columnar liquid crystalline phases with low isotropization temperatures. The effects of the distortion of the π systems on their π–π stacking and the optical properties of the resultant stacks in solution and in LC phases have been explored in detail. In one case (3 a) a particularly interesting phase change from crystalline into liquid crystalline could be observed upon annealing that was accompanied by a transformation from non-fluorescent H-type into strongly fluorescent J-type packing of the dyes.

  @article{CHEM:CHEM200600891, abstract = {A series of highly soluble and fluorescent core-twisted perylene bisimide dyes (PBIs) 3 a–f with different substituents at the bay area (1,6,7,12 positions of the perylene core) were synthesized and fully characterized by 1H NMR, UV/Vis spectroscopy, MS spectrometry, and elemental analysis. The π–π aggregation properties of these new functional dyes were investigated in detail both in solution and in condensed phase by UV/Vis and fluorescence spectroscopy, vapor pressure osmometry (VPO), differential scanning calorimetry (DSC), polarizing optical microscopy (POM), and X-ray diffraction. Concentration-dependent UV/Vis measurements and VPO analysis revealed that these core-twisted π-conjugated systems show distinct self-dimerization equilibria in apolar solvent methylcyclohexane (MCH) with dimerization constants between 1.3×104 and 30 M−1. The photoluminescence spectra of the dimers of PBIs 3 a–f exhibit bathochromic shifts of quite different magnitude which could be attributed to different longitudinal or rotational offsets between the dyes as well as differences in the respective π–π stacking distance. In condensed state, quite a few of these PBIs form luminescent rectangular or hexagonal columnar liquid crystalline phases with low isotropization temperatures. The effects of the distortion of the π systems on their π–π stacking and the optical properties of the resultant stacks in solution and in LC phases have been explored in detail. In one case (3 a) a particularly interesting phase change from crystalline into liquid crystalline could be observed upon annealing that was accompanied by a transformation from non-fluorescent H-type into strongly fluorescent J-type packing of the dyes.}, author = {Chen, Zhijian and Baumeister, Ute and Tschierske, Carsten and Würthner, Frank}, journal = {Chemistry – A European Journal}, keywords = {myown}, number = 2, pages = {450–465}, publisher = {WILEY-VCH Verlag}, title = {Effect of Core Twisting on Self-Assembly and Optical Properties of Perylene Bisimide Dyes in Solution and Columnar Liquid Crystalline Phases}, volume = 13, year = 2007 }

  %0 Journal Article %1 CHEM:CHEM200600891 %A Chen, Zhijian %A Baumeister, Ute %A Tschierske, Carsten %A Würthner, Frank %D 2007 %I WILEY-VCH Verlag %J Chemistry – A European Journal %N 2 %P 450--465 %R 10.1002/chem.200600891 %T Effect of Core Twisting on Self-Assembly and Optical Properties of Perylene Bisimide Dyes in Solution and Columnar Liquid Crystalline Phases %U http://dx.doi.org/10.1002/chem.200600891 %V 13 %X A series of highly soluble and fluorescent core-twisted perylene bisimide dyes (PBIs) 3 a–f with different substituents at the bay area (1,6,7,12 positions of the perylene core) were synthesized and fully characterized by 1H NMR, UV/Vis spectroscopy, MS spectrometry, and elemental analysis. The π–π aggregation properties of these new functional dyes were investigated in detail both in solution and in condensed phase by UV/Vis and fluorescence spectroscopy, vapor pressure osmometry (VPO), differential scanning calorimetry (DSC), polarizing optical microscopy (POM), and X-ray diffraction. Concentration-dependent UV/Vis measurements and VPO analysis revealed that these core-twisted π-conjugated systems show distinct self-dimerization equilibria in apolar solvent methylcyclohexane (MCH) with dimerization constants between 1.3×104 and 30 M−1. The photoluminescence spectra of the dimers of PBIs 3 a–f exhibit bathochromic shifts of quite different magnitude which could be attributed to different longitudinal or rotational offsets between the dyes as well as differences in the respective π–π stacking distance. In condensed state, quite a few of these PBIs form luminescent rectangular or hexagonal columnar liquid crystalline phases with low isotropization temperatures. The effects of the distortion of the π systems on their π–π stacking and the optical properties of the resultant stacks in solution and in LC phases have been explored in detail. In one case (3 a) a particularly interesting phase change from crystalline into liquid crystalline could be observed upon annealing that was accompanied by a transformation from non-fluorescent H-type into strongly fluorescent J-type packing of the dyes.
• Self-Assembled Single- and Double-Stack π-Aggregates of Chlorophyll Derivatives on Highly Ordered Pyrolytic Graphite. Huber, Valerie; Lysetska, Marina; Würthner, Frank. In Small, 3(6), pp. 1007–1014. 2007.
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  The highly efficient, light-harvesting antennae systems present in chlorosomes of green phototrophic bacteria, such as Chloroflexus aurantiacus, serve as a model for the design of bioinspired nanostructured materials. A semisynthetic zinc chlorin, derived from natural chlorophyll a, is used as a building block that self-assembles into excitonically coupled chromophore stacks. Temperature-dependent UV/Vis and circular dichroism spectroscopic measurements show the reversible formation of soluble chiral aggregates of this new zinc chlorin dye. High-resolution scanning tunneling microscopy and atomic force microscopy studies reveal the formation of two types of well-ordered π-stacked aggregates on highly ordered pyrolytic graphite.

  @article{SMLL:SMLL200600497, abstract = {The highly efficient, light-harvesting antennae systems present in chlorosomes of green phototrophic bacteria, such as Chloroflexus aurantiacus, serve as a model for the design of bioinspired nanostructured materials. A semisynthetic zinc chlorin, derived from natural chlorophyll a, is used as a building block that self-assembles into excitonically coupled chromophore stacks. Temperature-dependent UV/Vis and circular dichroism spectroscopic measurements show the reversible formation of soluble chiral aggregates of this new zinc chlorin dye. High-resolution scanning tunneling microscopy and atomic force microscopy studies reveal the formation of two types of well-ordered π-stacked aggregates on highly ordered pyrolytic graphite.}, author = {Huber, Valerie and Lysetska, Marina and Würthner, Frank}, journal = {Small}, keywords = {myown}, number = 6, pages = {1007–1014}, publisher = {WILEY-VCH Verlag}, title = {Self-Assembled Single- and Double-Stack π-Aggregates of Chlorophyll Derivatives on Highly Ordered Pyrolytic Graphite}, volume = 3, year = 2007 }

  %0 Journal Article %1 SMLL:SMLL200600497 %A Huber, Valerie %A Lysetska, Marina %A Würthner, Frank %D 2007 %I WILEY-VCH Verlag %J Small %N 6 %P 1007--1014 %R 10.1002/smll.200600497 %T Self-Assembled Single- and Double-Stack π-Aggregates of Chlorophyll Derivatives on Highly Ordered Pyrolytic Graphite %U http://dx.doi.org/10.1002/smll.200600497 %V 3 %X The highly efficient, light-harvesting antennae systems present in chlorosomes of green phototrophic bacteria, such as Chloroflexus aurantiacus, serve as a model for the design of bioinspired nanostructured materials. A semisynthetic zinc chlorin, derived from natural chlorophyll a, is used as a building block that self-assembles into excitonically coupled chromophore stacks. Temperature-dependent UV/Vis and circular dichroism spectroscopic measurements show the reversible formation of soluble chiral aggregates of this new zinc chlorin dye. High-resolution scanning tunneling microscopy and atomic force microscopy studies reveal the formation of two types of well-ordered π-stacked aggregates on highly ordered pyrolytic graphite.
• Synthesis and Optical Properties of Fluorescent Core-Trisubstituted Naphthalene Diimide Dyes. Röger, Cornelia; Ahmed, Shahadat; Würthner, Frank. 2007.
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  Efficient synthetic routes to hitherto unknown core-trisubstituted naphthalene diimides (NDIs) starting with 2,6-dichloro-substituted NDIs 1 are described. The reaction of NDIs 1 with ethylene diamine as solvent, affords the ethylene-diamine-bridged core-trisubstituted NDIs 2 in very good yield. The substitution of the chlorine atom of 2 with alkylamino or alkoxy nucleophiles leads to triamino- or alkoxy-diamino-substituted NDIs. UV/Vis spectroscopy revealed that the electronic properties of NDI chromophores bearing three core substituents are strongly influenced by the nature of the substituents. NDIs which are tri(alkylamino)-substituted at the naphthalene core exhibit high (up to 70%) fluorescence quantum yields.

  @article{rger2007synthesis, abstract = {Efficient synthetic routes to hitherto unknown core-trisubstituted naphthalene diimides (NDIs) starting with 2,6-dichloro-substituted NDIs 1 are described. The reaction of NDIs 1 with ethylene diamine as solvent, affords the ethylene-diamine-bridged core-trisubstituted NDIs 2 in very good yield. The substitution of the chlorine atom of 2 with alkylamino or alkoxy nucleophiles leads to triamino- or alkoxy-diamino-substituted NDIs. UV/Vis spectroscopy revealed that the electronic properties of NDI chromophores bearing three core substituents are strongly influenced by the nature of the substituents. NDIs which are tri(alkylamino)-substituted at the naphthalene core exhibit high (up to 70%) fluorescence quantum yields.}, author = {Röger, Cornelia and Ahmed, Shahadat and Würthner, Frank}, keywords = {dyes}, title = {Synthesis and Optical Properties of Fluorescent Core-Trisubstituted Naphthalene Diimide Dyes}, year = 2007 }

  %0 Journal Article %1 rger2007synthesis %A Röger, Cornelia %A Ahmed, Shahadat %A Würthner, Frank %D 2007 %R 10.1055/s-2007-983718 %T Synthesis and Optical Properties of Fluorescent Core-Trisubstituted Naphthalene Diimide Dyes %U https://www.thieme-connect.de/DOI/DOI?10.1055/s-2007-983718 %X Efficient synthetic routes to hitherto unknown core-trisubstituted naphthalene diimides (NDIs) starting with 2,6-dichloro-substituted NDIs 1 are described. The reaction of NDIs 1 with ethylene diamine as solvent, affords the ethylene-diamine-bridged core-trisubstituted NDIs 2 in very good yield. The substitution of the chlorine atom of 2 with alkylamino or alkoxy nucleophiles leads to triamino- or alkoxy-diamino-substituted NDIs. UV/Vis spectroscopy revealed that the electronic properties of NDI chromophores bearing three core substituents are strongly influenced by the nature of the substituents. NDIs which are tri(alkylamino)-substituted at the naphthalene core exhibit high (up to 70%) fluorescence quantum yields.
• Effects of Bay Substituents on the Racemization Barriers of Perylene Bisimides:  Resolution of Atropo-Enantiomers. Osswald, Peter; Würthner, Frank. In J. Am. Chem. Soc., 129(46), pp. 14319–14326. 2007.

  PMID: 17963383
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  The activation parameters for the interconversion of atropisomers (P- and M-enantiomer) of core-twisted perylene bisimides have been determined by dynamic NMR spectroscopy (DNMR) and time- and temperature-dependent CD spectroscopy. By comparing the activation parameters of a series of perylene bisimides containing halogen or aryloxy substituents in the bay area (1,6,7,12-positions), a clear structure−property relationship has been found that demonstrates that the kinetic and thermodynamic parameters for the inversion of enantiomers are dependent on the apparent overlap parameter ∑r* of the bay substituents. This study reveals a high stability (ΔG⧧368 K = 118 kJ/mol) for the atropo-enantiomers of tetrabromo-substituted perylene bisimide in solution. Accordingly, the enantiomers of this derivative could be resolved by HPLC on a chiral column. These enantiomers do not racemize in solution at room temperature and, thus, represent the first examples of enantiomerically pure core-twisted perylene bisimides.

  @article{doi:10.1021/ja074508e, abstract = {The activation parameters for the interconversion of atropisomers (P- and M-enantiomer) of core-twisted perylene bisimides have been determined by dynamic NMR spectroscopy (DNMR) and time- and temperature-dependent CD spectroscopy. By comparing the activation parameters of a series of perylene bisimides containing halogen or aryloxy substituents in the bay area (1,6,7,12-positions), a clear structure−property relationship has been found that demonstrates that the kinetic and thermodynamic parameters for the inversion of enantiomers are dependent on the apparent overlap parameter ∑r* of the bay substituents. This study reveals a high stability (ΔG⧧368 K = 118 kJ/mol) for the atropo-enantiomers of tetrabromo-substituted perylene bisimide in solution. Accordingly, the enantiomers of this derivative could be resolved by HPLC on a chiral column. These enantiomers do not racemize in solution at room temperature and, thus, represent the first examples of enantiomerically pure core-twisted perylene bisimides.}, author = {Osswald, Peter and Würthner, Frank}, journal = {J. Am. Chem. Soc.}, keywords = {myown}, note = {PMID: 17963383}, number = 46, pages = {14319-14326}, title = {Effects of Bay Substituents on the Racemization Barriers of Perylene Bisimides:  Resolution of Atropo-Enantiomers}, volume = 129, year = 2007 }

  %0 Journal Article %1 doi:10.1021/ja074508e %A Osswald, Peter %A Würthner, Frank %D 2007 %J J. Am. Chem. Soc. %N 46 %P 14319-14326 %R 10.1021/ja074508e %T Effects of Bay Substituents on the Racemization Barriers of Perylene Bisimides:  Resolution of Atropo-Enantiomers %U http://dx.doi.org/10.1021/ja074508e %V 129 %X The activation parameters for the interconversion of atropisomers (P- and M-enantiomer) of core-twisted perylene bisimides have been determined by dynamic NMR spectroscopy (DNMR) and time- and temperature-dependent CD spectroscopy. By comparing the activation parameters of a series of perylene bisimides containing halogen or aryloxy substituents in the bay area (1,6,7,12-positions), a clear structure−property relationship has been found that demonstrates that the kinetic and thermodynamic parameters for the inversion of enantiomers are dependent on the apparent overlap parameter ∑r* of the bay substituents. This study reveals a high stability (ΔG⧧368 K = 118 kJ/mol) for the atropo-enantiomers of tetrabromo-substituted perylene bisimide in solution. Accordingly, the enantiomers of this derivative could be resolved by HPLC on a chiral column. These enantiomers do not racemize in solution at room temperature and, thus, represent the first examples of enantiomerically pure core-twisted perylene bisimides.
• Helical Growth of Semiconducting Columnar Dye Assemblies Based on Chiral Perylene Bisimides. Dehm, Volker; Chen, Zhijian; Baumeister, Ute; Prins, Paulette; Siebbeles, Laurens D. A.; Würthner, Frank. In Organic Letters, 9(6), pp. 1085–1088. 2007.

  PMID: 17300201
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  A perylene bisimide derivative bearing two phenyl substituents with chiral solubilizing alkyl chains at the imide N atoms has been synthesized, and its self-assembly properties in solution and condensed phase have been investigated. Temperature-dependent CD spectra revealed the coexistence of two different kinds of chiral aggregates, differing in size and handedness. The chiral side chains effect a higher order within the self-assemblies, resulting in an increased charge-carrier mobility in the columnar liquid crystalline mesophase.

  @article{doi:10.1021/ol0700963, abstract = {A perylene bisimide derivative bearing two phenyl substituents with chiral solubilizing alkyl chains at the imide N atoms has been synthesized, and its self-assembly properties in solution and condensed phase have been investigated. Temperature-dependent CD spectra revealed the coexistence of two different kinds of chiral aggregates, differing in size and handedness. The chiral side chains effect a higher order within the self-assemblies, resulting in an increased charge-carrier mobility in the columnar liquid crystalline mesophase.}, author = {Dehm, Volker and Chen, Zhijian and Baumeister, Ute and Prins, Paulette and Siebbeles, Laurens D. A. and Würthner, Frank}, journal = {Organic Letters}, keywords = {myown}, note = {PMID: 17300201}, number = 6, pages = {1085-1088}, title = {Helical Growth of Semiconducting Columnar Dye Assemblies Based on Chiral Perylene Bisimides}, volume = 9, year = 2007 }

  %0 Journal Article %1 doi:10.1021/ol0700963 %A Dehm, Volker %A Chen, Zhijian %A Baumeister, Ute %A Prins, Paulette %A Siebbeles, Laurens D. A. %A Würthner, Frank %D 2007 %J Organic Letters %N 6 %P 1085-1088 %R 10.1021/ol0700963 %T Helical Growth of Semiconducting Columnar Dye Assemblies Based on Chiral Perylene Bisimides %U http://dx.doi.org/10.1021/ol0700963 %V 9 %X A perylene bisimide derivative bearing two phenyl substituents with chiral solubilizing alkyl chains at the imide N atoms has been synthesized, and its self-assembly properties in solution and condensed phase have been investigated. Temperature-dependent CD spectra revealed the coexistence of two different kinds of chiral aggregates, differing in size and handedness. The chiral side chains effect a higher order within the self-assemblies, resulting in an increased charge-carrier mobility in the columnar liquid crystalline mesophase.

• Electronic and Crystal Engineering of Acenes for Solution-Processible Self-Assembling Organic Semiconductors. Würthner, Frank; Schmidt, Rüdiger. In ChemPhysChem, 7(4), pp. 793–797. 2006.
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  @article{CPHC:CPHC200600078, author = {Würthner, Frank and Schmidt, Rüdiger}, journal = {ChemPhysChem}, keywords = {myown}, number = 4, pages = {793–797}, publisher = {WILEY-VCH Verlag}, title = {Electronic and Crystal Engineering of Acenes for Solution-Processible Self-Assembling Organic Semiconductors}, volume = 7, year = 2006 }

  %0 Journal Article %1 CPHC:CPHC200600078 %A Würthner, Frank %A Schmidt, Rüdiger %D 2006 %I WILEY-VCH Verlag %J ChemPhysChem %N 4 %P 793--797 %R 10.1002/cphc.200600078 %T Electronic and Crystal Engineering of Acenes for Solution-Processible Self-Assembling Organic Semiconductors %U http://dx.doi.org/10.1002/cphc.200600078 %V 7
• Highly soluble acenes as semiconductors for thin film transistors. Schmidt, Rudiger; Gottling, Silke; Leusser, Dirk; Stalke, Dietmar; Krause, Ana-Maria; Würthner, Frank. In J. Mater. Chem., 16(37), pp. 3708–3714. 2006.
  • [ Abstract ]
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  Acene derivatives 3, 5, 7 and 9 bearing two trimethoxyphenylethynyl substituents have been synthesized. The optical properties of these acenes have been investigated by UV/Vis and fluorescence spectroscopy and their eletrochemical properties have been elucidated by cyclic voltammetry (CV). X-Ray analysis of the anthracene and tetracene derivatives 3 and 5 has revealed a 1-D [small pi]-stacking in crystals of 3 and 5. In contrast to their parent hydrocarbons, the present disubstituted acenes are highly soluble in different solvents. Spin-coating has afforded amorphous thin films that exhibit field effect mobility. Best performance has been achieved for the OTFTs prepared from the pentacene derivative 7 with a field effect mobility of 1.9 [times] 10-5 cm2 V-1 s-1 and an on/off ratio of 103.

  @article{B607172D, abstract = {Acene derivatives 3{,} 5{,} 7 and 9 bearing two trimethoxyphenylethynyl substituents have been synthesized. The optical properties of these acenes have been investigated by UV/Vis and fluorescence spectroscopy and their eletrochemical properties have been elucidated by cyclic voltammetry (CV). X-Ray analysis of the anthracene and tetracene derivatives 3 and 5 has revealed a 1-D [small pi]-stacking in crystals of 3 and 5. In contrast to their parent hydrocarbons{,} the present disubstituted acenes are highly soluble in different solvents. Spin-coating has afforded amorphous thin films that exhibit field effect mobility. Best performance has been achieved for the OTFTs prepared from the pentacene derivative 7 with a field effect mobility of 1.9 [times] 10-5 cm2 V-1 s-1 and an on/off ratio of 103.}, author = {Schmidt, Rudiger and Gottling, Silke and Leusser, Dirk and Stalke, Dietmar and Krause, Ana-Maria and Würthner, Frank}, journal = {J. Mater. Chem.}, keywords = {myown}, number = 37, pages = {3708-3714}, publisher = {The Royal Society of Chemistry}, title = {Highly soluble acenes as semiconductors for thin film transistors}, volume = 16, year = 2006 }

  %0 Journal Article %1 B607172D %A Schmidt, Rudiger %A Gottling, Silke %A Leusser, Dirk %A Stalke, Dietmar %A Krause, Ana-Maria %A Würthner, Frank %D 2006 %I The Royal Society of Chemistry %J J. Mater. Chem. %N 37 %P 3708-3714 %R 10.1039/B607172D %T Highly soluble acenes as semiconductors for thin film transistors %U http://dx.doi.org/10.1039/B607172D %V 16 %X Acene derivatives 3, 5, 7 and 9 bearing two trimethoxyphenylethynyl substituents have been synthesized. The optical properties of these acenes have been investigated by UV/Vis and fluorescence spectroscopy and their eletrochemical properties have been elucidated by cyclic voltammetry (CV). X-Ray analysis of the anthracene and tetracene derivatives 3 and 5 has revealed a 1-D [small pi]-stacking in crystals of 3 and 5. In contrast to their parent hydrocarbons, the present disubstituted acenes are highly soluble in different solvents. Spin-coating has afforded amorphous thin films that exhibit field effect mobility. Best performance has been achieved for the OTFTs prepared from the pentacene derivative 7 with a field effect mobility of 1.9 [times] 10-5 cm2 V-1 s-1 and an on/off ratio of 103.
• Photoproduction of Proton Gradients with π-Stacked Fluorophore Scaffolds in Lipid Bilayers. Bhosale, Sheshanath; Sisson, Adam L.; Talukdar, Pinaki; Fürstenberg, Alexandre; Banerji, Natalie; Vauthey, Eric; Bollot, Guillaume; Mareda, Jiri; Röger, Cornelia; Würthner, Frank; Sakai, Naomi; Matile, Stefan. In Science, 313(5783), pp. 84–86. 2006.
  • [ Abstract ]
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  Rigid p-octiphenyl rods were used to create helical tetrameric π-stacks of blue, red-fluorescent naphthalene diimides that can span lipid bilayer membranes. In lipid vesicles containing quinone as electron acceptors and surrounded by ethylenediaminetetraacetic acid as hole acceptors, transmembrane proton gradients arose through quinone reduction upon excitation with visible light. Quantitative ultrafast and relatively long-lived charge separation was confirmed as the origin of photosynthetic activity by femtosecond fluorescence and transient absorption spectroscopy. Supramolecular self-organization was essential in that photoactivity was lost upon rod shortening (from p-octiphenyl to biphenyl) and chromophore expansion (from naphthalene diimide to perylene diimide). Ligand intercalation transformed the photoactive scaffolds into ion channels.

  @article{Bhosale84, abstract = {Rigid p-octiphenyl rods were used to create helical tetrameric π-stacks of blue, red-fluorescent naphthalene diimides that can span lipid bilayer membranes. In lipid vesicles containing quinone as electron acceptors and surrounded by ethylenediaminetetraacetic acid as hole acceptors, transmembrane proton gradients arose through quinone reduction upon excitation with visible light. Quantitative ultrafast and relatively long-lived charge separation was confirmed as the origin of photosynthetic activity by femtosecond fluorescence and transient absorption spectroscopy. Supramolecular self-organization was essential in that photoactivity was lost upon rod shortening (from p-octiphenyl to biphenyl) and chromophore expansion (from naphthalene diimide to perylene diimide). Ligand intercalation transformed the photoactive scaffolds into ion channels.}, author = {Bhosale, Sheshanath and Sisson, Adam L. and Talukdar, Pinaki and Fürstenberg, Alexandre and Banerji, Natalie and Vauthey, Eric and Bollot, Guillaume and Mareda, Jiri and Röger, Cornelia and Würthner, Frank and Sakai, Naomi and Matile, Stefan}, journal = {Science}, keywords = {myown}, number = 5783, pages = {84–86}, publisher = {American Association for the Advancement of Science}, title = {Photoproduction of Proton Gradients with π-Stacked Fluorophore Scaffolds in Lipid Bilayers}, volume = 313, year = 2006 }

  %0 Journal Article %1 Bhosale84 %A Bhosale, Sheshanath %A Sisson, Adam L. %A Talukdar, Pinaki %A Fürstenberg, Alexandre %A Banerji, Natalie %A Vauthey, Eric %A Bollot, Guillaume %A Mareda, Jiri %A Röger, Cornelia %A Würthner, Frank %A Sakai, Naomi %A Matile, Stefan %D 2006 %I American Association for the Advancement of Science %J Science %N 5783 %P 84--86 %R 10.1126/science.1126524 %T Photoproduction of Proton Gradients with π-Stacked Fluorophore Scaffolds in Lipid Bilayers %U http://science.sciencemag.org/content/313/5783/84 %V 313 %X Rigid p-octiphenyl rods were used to create helical tetrameric π-stacks of blue, red-fluorescent naphthalene diimides that can span lipid bilayer membranes. In lipid vesicles containing quinone as electron acceptors and surrounded by ethylenediaminetetraacetic acid as hole acceptors, transmembrane proton gradients arose through quinone reduction upon excitation with visible light. Quantitative ultrafast and relatively long-lived charge separation was confirmed as the origin of photosynthetic activity by femtosecond fluorescence and transient absorption spectroscopy. Supramolecular self-organization was essential in that photoactivity was lost upon rod shortening (from p-octiphenyl to biphenyl) and chromophore expansion (from naphthalene diimide to perylene diimide). Ligand intercalation transformed the photoactive scaffolds into ion channels.
• Synthesis and Optical and Electrochemical Properties of Core-Fluorinated Perylene Bisimides. Würthner, Frank; Osswald, Peter; Schmidt, Rüdiger; Kaiser, Theo E.; Mansikkamäki, Heidi; Könemann, Martin. In Organic Letters, 8(17), pp. 3765–3768. 2006.

  PMID: 16898812
  • [ Abstract ]
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  A series of bay position difluoro- or tetrafluoro-substituted perylene bisimides have been synthesized by nucleophilic halogen exchange reaction of the corresponding dibromo- and tetrachloro-substituted perylene bisimides, respectively, with potassium fluoride. Compared to the parent unsubstituted perylene bisimides, these compounds display hypsochromically shifted absorption and fluorescence spectra with fluorescence quantum yields up to unity enabling bright yellow emission. Their electrochemical properties and crystal structures of two perylene bisimides are also reported.

  @article{doi:10.1021/ol0613416, abstract = {A series of bay position difluoro- or tetrafluoro-substituted perylene bisimides have been synthesized by nucleophilic halogen exchange reaction of the corresponding dibromo- and tetrachloro-substituted perylene bisimides, respectively, with potassium fluoride. Compared to the parent unsubstituted perylene bisimides, these compounds display hypsochromically shifted absorption and fluorescence spectra with fluorescence quantum yields up to unity enabling bright yellow emission. Their electrochemical properties and crystal structures of two perylene bisimides are also reported.}, author = {Würthner, Frank and Osswald, Peter and Schmidt, Rüdiger and Kaiser, Theo E. and Mansikkamäki, Heidi and Könemann, Martin}, journal = {Organic Letters}, keywords = {myown}, note = {PMID: 16898812}, number = 17, pages = {3765-3768}, title = {Synthesis and Optical and Electrochemical Properties of Core-Fluorinated Perylene Bisimides}, volume = 8, year = 2006 }

  %0 Journal Article %1 doi:10.1021/ol0613416 %A Würthner, Frank %A Osswald, Peter %A Schmidt, Rüdiger %A Kaiser, Theo E. %A Mansikkamäki, Heidi %A Könemann, Martin %D 2006 %J Organic Letters %N 17 %P 3765-3768 %R 10.1021/ol0613416 %T Synthesis and Optical and Electrochemical Properties of Core-Fluorinated Perylene Bisimides %U http://dx.doi.org/10.1021/ol0613416 %V 8 %X A series of bay position difluoro- or tetrafluoro-substituted perylene bisimides have been synthesized by nucleophilic halogen exchange reaction of the corresponding dibromo- and tetrachloro-substituted perylene bisimides, respectively, with potassium fluoride. Compared to the parent unsubstituted perylene bisimides, these compounds display hypsochromically shifted absorption and fluorescence spectra with fluorescence quantum yields up to unity enabling bright yellow emission. Their electrochemical properties and crystal structures of two perylene bisimides are also reported.
• Functional organogels from highly efficient organogelator based on perylene bisimide semiconductor. Li, Xue-Qing; Stepanenko, Vladimir; Chen, Zhijian; Prins, Paulette; Siebbeles, Laurens D. A.; Würthner, Frank. In Chem. Commun., (37), pp. 3871–3873. 2006.
  • [ Abstract ]
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  A new n-type semiconducting perylene bisimide dye has been synthesized that gelates a broad variety of organic solvents to afford well-defined nano- and mesoscopic helical fibers and bundles.

  @article{B611422A, abstract = {A new n-type semiconducting perylene bisimide dye has been synthesized that gelates a broad variety of organic solvents to afford well-defined nano- and mesoscopic helical fibers and bundles.}, author = {Li, Xue-Qing and Stepanenko, Vladimir and Chen, Zhijian and Prins, Paulette and Siebbeles, Laurens D. A. and Würthner, Frank}, journal = {Chem. Commun.}, keywords = {myown}, number = 37, pages = {3871-3873}, publisher = {The Royal Society of Chemistry}, title = {Functional organogels from highly efficient organogelator based on perylene bisimide semiconductor}, year = 2006 }

  %0 Journal Article %1 B611422A %A Li, Xue-Qing %A Stepanenko, Vladimir %A Chen, Zhijian %A Prins, Paulette %A Siebbeles, Laurens D. A. %A Würthner, Frank %D 2006 %I The Royal Society of Chemistry %J Chem. Commun. %N 37 %P 3871-3873 %R 10.1039/B611422A %T Functional organogels from highly efficient organogelator based on perylene bisimide semiconductor %U http://dx.doi.org/10.1039/B611422A %X A new n-type semiconducting perylene bisimide dye has been synthesized that gelates a broad variety of organic solvents to afford well-defined nano- and mesoscopic helical fibers and bundles.
• The Importance of Nanoscopic Ordering on the Kinetics of Photoinduced Charge Transfer in Aggregated π-Conjugated Hydrogen-Bonded Donor−Acceptor Systems. Beckers, Edwin H. A.; Chen, Zhijian; Meskers, Stefan C. J.; Jonkheijm, Pascal; Schenning, Albertus P. H. J.; Li, Xue-Qing; Osswald, Peter; Würthner, Frank; Janssen, René A. J. In The Journal of Physical Chemistry B, 110(34), pp. 16967–16978. 2006.

  PMID: 16927989
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  Aggregated complexes of diaminotriazine oligo(p-phenylene vinylene) (OPV) units hydrogen bonded to different complementary perylene bisimide (PERY) compounds have been investigated by means of absorption, circular dichroism, photoluminescence, and photoinduced absorption spectroscopy. These studies reveal that in the aggregated state an ultrafast photoinduced charge separation occurs via an intermolecular pathway in the J-type stack of hydrogen-bonded OPV-PERY arrays. The subsequent charge recombination reaction strongly depends on small structural differences within the J-type geometry as revealed by comparison of stacked supramolecular dimers, trimers, and covalently OPV-PERY linked systems. A coupled oscillator model is used to analyze absorption and circular dichroism spectra and to identify intermolecular arrangements that are consistent with the experimental spectra and the charge-transfer kinetics.

  @article{doi:10.1021/jp0624496, abstract = {Aggregated complexes of diaminotriazine oligo(p-phenylene vinylene) (OPV) units hydrogen bonded to different complementary perylene bisimide (PERY) compounds have been investigated by means of absorption, circular dichroism, photoluminescence, and photoinduced absorption spectroscopy. These studies reveal that in the aggregated state an ultrafast photoinduced charge separation occurs via an intermolecular pathway in the J-type stack of hydrogen-bonded OPV-PERY arrays. The subsequent charge recombination reaction strongly depends on small structural differences within the J-type geometry as revealed by comparison of stacked supramolecular dimers, trimers, and covalently OPV-PERY linked systems. A coupled oscillator model is used to analyze absorption and circular dichroism spectra and to identify intermolecular arrangements that are consistent with the experimental spectra and the charge-transfer kinetics.}, author = {Beckers, Edwin H. A. and Chen, Zhijian and Meskers, Stefan C. J. and Jonkheijm, Pascal and Schenning, Albertus P. H. J. and Li, Xue-Qing and Osswald, Peter and Würthner, Frank and Janssen, René A. J.}, journal = {The Journal of Physical Chemistry B}, keywords = {myown}, note = {PMID: 16927989}, number = 34, pages = {16967-16978}, title = {The Importance of Nanoscopic Ordering on the Kinetics of Photoinduced Charge Transfer in Aggregated π-Conjugated Hydrogen-Bonded Donor−Acceptor Systems}, volume = 110, year = 2006 }

  %0 Journal Article %1 doi:10.1021/jp0624496 %A Beckers, Edwin H. A. %A Chen, Zhijian %A Meskers, Stefan C. J. %A Jonkheijm, Pascal %A Schenning, Albertus P. H. J. %A Li, Xue-Qing %A Osswald, Peter %A Würthner, Frank %A Janssen, René A. J. %D 2006 %J The Journal of Physical Chemistry B %N 34 %P 16967-16978 %R 10.1021/jp0624496 %T The Importance of Nanoscopic Ordering on the Kinetics of Photoinduced Charge Transfer in Aggregated π-Conjugated Hydrogen-Bonded Donor−Acceptor Systems %U http://dx.doi.org/10.1021/jp0624496 %V 110 %X Aggregated complexes of diaminotriazine oligo(p-phenylene vinylene) (OPV) units hydrogen bonded to different complementary perylene bisimide (PERY) compounds have been investigated by means of absorption, circular dichroism, photoluminescence, and photoinduced absorption spectroscopy. These studies reveal that in the aggregated state an ultrafast photoinduced charge separation occurs via an intermolecular pathway in the J-type stack of hydrogen-bonded OPV-PERY arrays. The subsequent charge recombination reaction strongly depends on small structural differences within the J-type geometry as revealed by comparison of stacked supramolecular dimers, trimers, and covalently OPV-PERY linked systems. A coupled oscillator model is used to analyze absorption and circular dichroism spectra and to identify intermolecular arrangements that are consistent with the experimental spectra and the charge-transfer kinetics.
• On the geometry dependence of molecular dimer spectra with an application to aggregates of perylene bisimide. Seibt, J.; Marquetand, P.; Engel, Volker; Chen, Z.; Dehm, V.; Würthner, F. In Chemical Physics, 328(1), pp. 354–362. 2006.
  • [ Abstract ]
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  Abstract We study spectroscopic properties of molecular dimers coupled by dipole–dipole interactions within the framework of time-dependent quantum mechanics. A systematic variation of the dimer geometry allows to establish relationships between the latter and structures in the absorption spectrum. The theoretical model is constructed with the purpose to characterize the changes in absorption and emission properties arising upon aggregation of perylene bisimides. Measured and calculated spectra are compared, thereby addressing the question if a simple exciton model is capable to describe excited state properties of nanoaggregates of these molecules.

  @article{SEIBT2006354, abstract = {Abstract We study spectroscopic properties of molecular dimers coupled by dipole–dipole interactions within the framework of time-dependent quantum mechanics. A systematic variation of the dimer geometry allows to establish relationships between the latter and structures in the absorption spectrum. The theoretical model is constructed with the purpose to characterize the changes in absorption and emission properties arising upon aggregation of perylene bisimides. Measured and calculated spectra are compared, thereby addressing the question if a simple exciton model is capable to describe excited state properties of nanoaggregates of these molecules.}, author = {Seibt, J. and Marquetand, P. and Engel, Volker and Chen, Z. and Dehm, V. and Würthner, F.}, journal = {Chemical Physics}, keywords = {quantum}, number = 1, pages = {354 - 362}, title = {On the geometry dependence of molecular dimer spectra with an application to aggregates of perylene bisimide}, volume = 328, year = 2006 }

  %0 Journal Article %1 SEIBT2006354 %A Seibt, J. %A Marquetand, P. %A Engel, Volker %A Chen, Z. %A Dehm, V. %A Würthner, F. %D 2006 %J Chemical Physics %N 1 %P 354 - 362 %R https://doi.org/10.1016/j.chemphys.2006.07.023 %T On the geometry dependence of molecular dimer spectra with an application to aggregates of perylene bisimide %U http://www.sciencedirect.com/science/article/pii/S0301010406004071 %V 328 %X Abstract We study spectroscopic properties of molecular dimers coupled by dipole–dipole interactions within the framework of time-dependent quantum mechanics. A systematic variation of the dimer geometry allows to establish relationships between the latter and structures in the absorption spectrum. The theoretical model is constructed with the purpose to characterize the changes in absorption and emission properties arising upon aggregation of perylene bisimides. Measured and calculated spectra are compared, thereby addressing the question if a simple exciton model is capable to describe excited state properties of nanoaggregates of these molecules.
• Hydrogen-Bond-Directed Head-to-Tail Orientation of Dipolar Merocyanine Dyes: A Strategy for the Design of Electrooptical Materials. Würthner, Frank; Schmidt, Johann; Stolte, Matthias; Wortmann, Rüdiger. In Angew. Chem. Int. Ed., 45(23), pp. 3842–3846. 2006.
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  @article{ANIE:ANIE200504581, author = {Würthner, Frank and Schmidt, Johann and Stolte, Matthias and Wortmann, Rüdiger}, journal = {Angew. Chem. Int. Ed.}, keywords = {myown}, number = 23, pages = {3842–3846}, publisher = {WILEY-VCH Verlag}, title = {Hydrogen-Bond-Directed Head-to-Tail Orientation of Dipolar Merocyanine Dyes: A Strategy for the Design of Electrooptical Materials}, volume = 45, year = 2006 }

  %0 Journal Article %1 ANIE:ANIE200504581 %A Würthner, Frank %A Schmidt, Johann %A Stolte, Matthias %A Wortmann, Rüdiger %D 2006 %I WILEY-VCH Verlag %J Angew. Chem. Int. Ed. %N 23 %P 3842--3846 %R 10.1002/anie.200504581 %T Hydrogen-Bond-Directed Head-to-Tail Orientation of Dipolar Merocyanine Dyes: A Strategy for the Design of Electrooptical Materials %U http://dx.doi.org/10.1002/anie.200504581 %V 45
• Synthesis and Optical and Redox Properties of Core-Substituted Naphthalene Diimide Dyes. Thalacker, Christoph; Röger, Cornelia; Würthner, Frank. In The Journal of Organic Chemistry, 71(21), pp. 8098–8105. 2006.

  PMID: 17025298
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  2,6-Dichloronaphthalene dianhydride has been synthesized by a modified procedure. The imidization of this dichlorinated anhydride with amines and subsequent stepwise nucleophilic exchange of the chlorine atoms by alkyl- or arylamines afforded a series of hitherto unknown monoamino- and diamino-substituted naphthalene diimides. An alternative route for the synthesis of diamino-substituted naphthalene diimides is also reported. Optical and electrochemical properties of the newly synthesized amino-functionalized naphthalene diimides were studied in detail. The absorption maxima (530−620 nm) of these dyes are appreciably bathochromically shifted compared to those of the corresponding core-unsubstituted compounds. At the naphthalene core alkylamino-substituted diimides exhibit fluorescence quantum yields up to 60\%.

  @article{doi:10.1021/jo0612269, abstract = {2,6-Dichloronaphthalene dianhydride has been synthesized by a modified procedure. The imidization of this dichlorinated anhydride with amines and subsequent stepwise nucleophilic exchange of the chlorine atoms by alkyl- or arylamines afforded a series of hitherto unknown monoamino- and diamino-substituted naphthalene diimides. An alternative route for the synthesis of diamino-substituted naphthalene diimides is also reported. Optical and electrochemical properties of the newly synthesized amino-functionalized naphthalene diimides were studied in detail. The absorption maxima (530−620 nm) of these dyes are appreciably bathochromically shifted compared to those of the corresponding core-unsubstituted compounds. At the naphthalene core alkylamino-substituted diimides exhibit fluorescence quantum yields up to 60\%.}, author = {Thalacker, Christoph and Röger, Cornelia and Würthner, Frank}, journal = {The Journal of Organic Chemistry}, keywords = {myown}, note = {PMID: 17025298}, number = 21, pages = {8098-8105}, title = {Synthesis and Optical and Redox Properties of Core-Substituted Naphthalene Diimide Dyes}, volume = 71, year = 2006 }

  %0 Journal Article %1 doi:10.1021/jo0612269 %A Thalacker, Christoph %A Röger, Cornelia %A Würthner, Frank %D 2006 %J The Journal of Organic Chemistry %N 21 %P 8098-8105 %R 10.1021/jo0612269 %T Synthesis and Optical and Redox Properties of Core-Substituted Naphthalene Diimide Dyes %U http://dx.doi.org/10.1021/jo0612269 %V 71 %X 2,6-Dichloronaphthalene dianhydride has been synthesized by a modified procedure. The imidization of this dichlorinated anhydride with amines and subsequent stepwise nucleophilic exchange of the chlorine atoms by alkyl- or arylamines afforded a series of hitherto unknown monoamino- and diamino-substituted naphthalene diimides. An alternative route for the synthesis of diamino-substituted naphthalene diimides is also reported. Optical and electrochemical properties of the newly synthesized amino-functionalized naphthalene diimides were studied in detail. The absorption maxima (530−620 nm) of these dyes are appreciably bathochromically shifted compared to those of the corresponding core-unsubstituted compounds. At the naphthalene core alkylamino-substituted diimides exhibit fluorescence quantum yields up to 60\%.
• Rigid-Rod Metallosupramolecular Polymers of Dendronized Diazadibenzoperylene Dyes. Würthner, Frank; Stepanenko, Vladimir; Sautter, Armin. In Angew. Chem. Int. Ed., 45(12), pp. 1939–1942. 2006.
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  @article{ANGE:ANGE200503717, author = {Würthner, Frank and Stepanenko, Vladimir and Sautter, Armin}, journal = {Angew. Chem. Int. Ed.}, keywords = {myown}, number = 12, pages = {1939 - 1942}, publisher = {WILEY-VCH Verlag}, title = {Rigid-Rod Metallosupramolecular Polymers of Dendronized Diazadibenzoperylene Dyes}, volume = 45, year = 2006 }

  %0 Journal Article %1 ANGE:ANGE200503717 %A Würthner, Frank %A Stepanenko, Vladimir %A Sautter, Armin %D 2006 %I WILEY-VCH Verlag %J Angew. Chem. Int. Ed. %N 12 %P 1939 - 1942 %R 10.1002/anie.200503717 %T Rigid-Rod Metallosupramolecular Polymers of Dendronized Diazadibenzoperylene Dyes %U https://onlinelibrary.wiley.com/doi/full/10.1002/anie.200503717 %V 45
• Fluorescent H-Aggregates of Merocyanine Dyes. Rösch, Ulrich; Yao, Sheng; Wortmann, Rüdiger; Würthner, Frank. In Angew. Chem. Int. Ed., 45(42), pp. 7026–7030. 2006.
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  @article{ANGE:ANGE200602286, author = {Rösch, Ulrich and Yao, Sheng and Wortmann, Rüdiger and Würthner, Frank}, journal = {Angew. Chem. Int. Ed.}, keywords = {myown}, number = 42, pages = {7026 - 7030}, publisher = {WILEY-VCH Verlag}, title = {Fluorescent H-Aggregates of Merocyanine Dyes}, volume = 45, year = 2006 }

  %0 Journal Article %1 ANGE:ANGE200602286 %A Rösch, Ulrich %A Yao, Sheng %A Wortmann, Rüdiger %A Würthner, Frank %D 2006 %I WILEY-VCH Verlag %J Angew. Chem. Int. Ed. %N 42 %P 7026 - 7030 %R 10.1002/anie.200602286 %T Fluorescent H-Aggregates of Merocyanine Dyes %U https://onlinelibrary.wiley.com/doi/10.1002/anie.200602286 %V 45
• Generating a Photocurrent on the Nanometer Scale. Würthner, Frank. In Science, 314(5806), pp. 1693–1694. 2006.
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  @article{W{\"u}rthner1693, author = {Würthner, Frank}, journal = {Science}, keywords = {myown}, number = 5806, pages = {1693-1694}, publisher = {American Association for the Advancement of Science}, title = {Generating a Photocurrent on the Nanometer Scale}, volume = 314, year = 2006 }

  %0 Journal Article %1 W\"urthner1693 %A Würthner, Frank %D 2006 %I American Association for the Advancement of Science %J Science %N 5806 %P 1693-1694 %R 10.1126/science.1136984 %T Generating a Photocurrent on the Nanometer Scale %U http://science.sciencemag.org/content/314/5806/1693 %V 314
• Efficient Energy Transfer from Peripheral Chromophores to the Self-Assembled Zinc Chlorin Rod Antenna:  A Bioinspired Light-Harvesting System to Bridge the “Green Gap.”. Röger, Cornelia; Müller, Marc G.; Lysetska, Marina; Miloslavina, Yulia; Holzwarth, Alfred R.; Würthner, Frank. In J. Am. Chem. Soc., 128(20), pp. 6542–6543. 2006.

  PMID: 16704238
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  An artificial light-harvesting rod aggregate based on zinc chlorin and covalently linked naphthalene bisimide chromophore has been realized by self-assembly. Efficient energy transfer (φET ≥ 0.99) takes place upon excitation at 620 nm from peripheral naphthalene bisimides to the zinc chlorin rod aggregate backbone. The appended naphthalene bisimide dyes improve the total LH efficiency of the rod aggregate by 26\%. Thus, the present bioinspired antenna system is promising for application in nanodevices for the effective utilization of solar energy by bridging the “green gap”.

  @article{doi:10.1021/ja0584469, abstract = {An artificial light-harvesting rod aggregate based on zinc chlorin and covalently linked naphthalene bisimide chromophore has been realized by self-assembly. Efficient energy transfer (φET ≥ 0.99) takes place upon excitation at 620 nm from peripheral naphthalene bisimides to the zinc chlorin rod aggregate backbone. The appended naphthalene bisimide dyes improve the total LH efficiency of the rod aggregate by 26\%. Thus, the present bioinspired antenna system is promising for application in nanodevices for the effective utilization of solar energy by bridging the “green gap”.}, author = {Röger, Cornelia and Müller, Marc G. and Lysetska, Marina and Miloslavina, Yulia and Holzwarth, Alfred R. and Würthner, Frank}, journal = {J. Am. Chem. Soc.}, keywords = {myown}, note = {PMID: 16704238}, number = 20, pages = {6542-6543}, title = {Efficient Energy Transfer from Peripheral Chromophores to the Self-Assembled Zinc Chlorin Rod Antenna:  A Bioinspired Light-Harvesting System to Bridge the “Green Gap”}, volume = 128, year = 2006 }

  %0 Journal Article %1 doi:10.1021/ja0584469 %A Röger, Cornelia %A Müller, Marc G. %A Lysetska, Marina %A Miloslavina, Yulia %A Holzwarth, Alfred R. %A Würthner, Frank %D 2006 %J J. Am. Chem. Soc. %N 20 %P 6542-6543 %R 10.1021/ja0584469 %T Efficient Energy Transfer from Peripheral Chromophores to the Self-Assembled Zinc Chlorin Rod Antenna:  A Bioinspired Light-Harvesting System to Bridge the “Green Gap” %U http://dx.doi.org/10.1021/ja0584469 %V 128 %X An artificial light-harvesting rod aggregate based on zinc chlorin and covalently linked naphthalene bisimide chromophore has been realized by self-assembly. Efficient energy transfer (φET ≥ 0.99) takes place upon excitation at 620 nm from peripheral naphthalene bisimides to the zinc chlorin rod aggregate backbone. The appended naphthalene bisimide dyes improve the total LH efficiency of the rod aggregate by 26\%. Thus, the present bioinspired antenna system is promising for application in nanodevices for the effective utilization of solar energy by bridging the “green gap”.
• Influence of Intermolecular Orientation on the Photoinduced Charge Transfer Kinetics in Self-Assembled Aggregates of Donor−Acceptor Arrays. Beckers, Edwin H. A.; Meskers, Stefan C. J.; Schenning, Albertus P. H. J.; Chen, Zhijian; Würthner, Frank; Marsal, Philippe; Beljonne, David; Cornil, Jérôme; Janssen, René A. J. In J. Am. Chem. Soc., 128(2), pp. 649–657. 2006.

  PMID: 16402853
  • [ Abstract ]
  • [ BibTeX ]
  • [ EndNote ]
  • [ DOI ]
  The kinetics of photoinduced charge transfer reactions in covalently linked donor−acceptor molecules often undergoes dramatic changes when these molecules self-assemble from a molecular dissolved state into a nanoaggregate. Frequently, the origin of these changes is only partially understood. In this paper, we describe the intermolecular spatial organization of three homologous arrays, consisting of a central perylene bisimide (PERY) acceptor moiety and two oligo(p-phenylene vinylene) (OPV) donor units, in nanoaggregates and identify both face-to-face (H-type) and slipped (J-type) stacking of the OPV and PERY chromophores. For the J-type aggregates, short intermolecular OPV−PERY distances are created that give rise to a charge-transfer absorption band. The proximity of the donor and acceptor groups in the J-type aggregates enables a highly efficient photoinduced charge separation with a rate (kcs > 1012 s-1) that significantly exceeds the rate of the intramolecular charge transfer of the same compounds when molecularly dissolved, even in the most polar media. In the H-type aggregates, on the other hand, the intermolecular OPV−PERY distance is not reduced compared to the intramolecular separation, and hence, the rates of the electron transfer reactions are not significantly affected compared to the molecular dissolved state. Similar to the forward electron transfer, the kinetics of the charge recombination in the aggregated state can be understood by considering the different interchromophoric distances that occur in the H- and J-type aggregates. These results provide the first consistent rationalization of the remarkable differences that are observed for photoinduced charge-transfer reactions of donor−acceptor compounds in molecularly dissolved versus aggregated states.

  @article{doi:10.1021/ja0568042, abstract = {The kinetics of photoinduced charge transfer reactions in covalently linked donor−acceptor molecules often undergoes dramatic changes when these molecules self-assemble from a molecular dissolved state into a nanoaggregate. Frequently, the origin of these changes is only partially understood. In this paper, we describe the intermolecular spatial organization of three homologous arrays, consisting of a central perylene bisimide (PERY) acceptor moiety and two oligo(p-phenylene vinylene) (OPV) donor units, in nanoaggregates and identify both face-to-face (H-type) and slipped (J-type) stacking of the OPV and PERY chromophores. For the J-type aggregates, short intermolecular OPV−PERY distances are created that give rise to a charge-transfer absorption band. The proximity of the donor and acceptor groups in the J-type aggregates enables a highly efficient photoinduced charge separation with a rate (kcs > 1012 s-1) that significantly exceeds the rate of the intramolecular charge transfer of the same compounds when molecularly dissolved, even in the most polar media. In the H-type aggregates, on the other hand, the intermolecular OPV−PERY distance is not reduced compared to the intramolecular separation, and hence, the rates of the electron transfer reactions are not significantly affected compared to the molecular dissolved state. Similar to the forward electron transfer, the kinetics of the charge recombination in the aggregated state can be understood by considering the different interchromophoric distances that occur in the H- and J-type aggregates. These results provide the first consistent rationalization of the remarkable differences that are observed for photoinduced charge-transfer reactions of donor−acceptor compounds in molecularly dissolved versus aggregated states.}, author = {Beckers, Edwin H. A. and Meskers, Stefan C. J. and Schenning, Albertus P. H. J. and Chen, Zhijian and Würthner, Frank and Marsal, Philippe and Beljonne, David and Cornil, Jérôme and Janssen, René A. J.}, journal = {J. Am. Chem. Soc.}, keywords = {myown}, note = {PMID: 16402853}, number = 2, pages = {649-657}, title = {Influence of Intermolecular Orientation on the Photoinduced Charge Transfer Kinetics in Self-Assembled Aggregates of Donor−Acceptor Arrays}, volume = 128, year = 2006 }

  %0 Journal Article %1 doi:10.1021/ja0568042 %A Beckers, Edwin H. A. %A Meskers, Stefan C. J. %A Schenning, Albertus P. H. J. %A Chen, Zhijian %A Würthner, Frank %A Marsal, Philippe %A Beljonne, David %A Cornil, Jérôme %A Janssen, René A. J. %D 2006 %J J. Am. Chem. Soc. %N 2 %P 649-657 %R 10.1021/ja0568042 %T Influence of Intermolecular Orientation on the Photoinduced Charge Transfer Kinetics in Self-Assembled Aggregates of Donor−Acceptor Arrays %U http://dx.doi.org/10.1021/ja0568042 %V 128 %X The kinetics of photoinduced charge transfer reactions in covalently linked donor−acceptor molecules often undergoes dramatic changes when these molecules self-assemble from a molecular dissolved state into a nanoaggregate. Frequently, the origin of these changes is only partially understood. In this paper, we describe the intermolecular spatial organization of three homologous arrays, consisting of a central perylene bisimide (PERY) acceptor moiety and two oligo(p-phenylene vinylene) (OPV) donor units, in nanoaggregates and identify both face-to-face (H-type) and slipped (J-type) stacking of the OPV and PERY chromophores. For the J-type aggregates, short intermolecular OPV−PERY distances are created that give rise to a charge-transfer absorption band. The proximity of the donor and acceptor groups in the J-type aggregates enables a highly efficient photoinduced charge separation with a rate (kcs > 1012 s-1) that significantly exceeds the rate of the intramolecular charge transfer of the same compounds when molecularly dissolved, even in the most polar media. In the H-type aggregates, on the other hand, the intermolecular OPV−PERY distance is not reduced compared to the intramolecular separation, and hence, the rates of the electron transfer reactions are not significantly affected compared to the molecular dissolved state. Similar to the forward electron transfer, the kinetics of the charge recombination in the aggregated state can be understood by considering the different interchromophoric distances that occur in the H- and J-type aggregates. These results provide the first consistent rationalization of the remarkable differences that are observed for photoinduced charge-transfer reactions of donor−acceptor compounds in molecularly dissolved versus aggregated states.
• Light-Harvesting Metallosupramolecular Squares Composed of Perylene Bisimide Walls and Fluorescent Antenna Dyes. You, Chang-Cheng; Hippius, Catharina; Grüne, Matthias; Würthner, Frank. In Chemistry – A European Journal, 12(28), pp. 7510–7519. 2006.
  • [ Abstract ]
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  The fluorescent dye 4-dimethylamino-1,8-naphthalimide was incorporated at the bay area of N,N′-bispyridyl perylene bisimide to afford a fourfold-functionalized perylene bisimide ligand. Through self-assembly directed by metal-ion coordination, a multichromophore supramolecular entity composed of sixteen dimethylaminonaphthalimide antennas and a perylene bisimide-walled square core was subsequently constructed from this linear ditopic ligand and 90° metal corner [Pd(dppp)](OTf)2 (dppp=1,3-bis(diphenylphosphino)propane; OTf=trifluoromethanesulfonate) in good yield. The isolated metallosupramolecular square was characterized by elemental analysis and 1H, 13C, and 31P1H NMR and UV/Vis spectroscopy. Furthermore, by means of 1H NMR diffusion-ordered spectroscopy (DOSY) the dimension of this assembly was evaluated by employing a previously reported perylene bisimide ligand and its square assembly as references. The results obtained confirm the square framework of the current assembly. The optical properties of this multichromophore dye assembly were investigated by UV/Vis and steady-state and time-resolved fluorescence spectroscopy. It was revealed that light captured by dimethylaminonaphthalimide antennas could be efficiently transported to the perylene bisimide core by a fluorescence resonance mechanism (energy-transfer efficiency E=95 %), and this resulted in almost exclusive detection of intense perylene bisimide emission, irrespective of the excitation wavelength applied. The present square scaffold containing aminonaphthalimide antenna dyes exhibits more than seven times higher fluorescence quantum yield (Φfl=0.37) than a previously reported pyrene-bearing perylene bisimide-walled square (Φfl=0.05). Thus, this multichromophore square assembly with aminonaphthalimide antenna dyes is an artificial model for the cyclic light-harvesting complexes in purple bacteria.

  @article{CHEM:CHEM200600413, abstract = {The fluorescent dye 4-dimethylamino-1,8-naphthalimide was incorporated at the bay area of N,N′-bispyridyl perylene bisimide to afford a fourfold-functionalized perylene bisimide ligand. Through self-assembly directed by metal-ion coordination, a multichromophore supramolecular entity composed of sixteen dimethylaminonaphthalimide antennas and a perylene bisimide-walled square core was subsequently constructed from this linear ditopic ligand and 90° metal corner [Pd(dppp)](OTf)2 (dppp=1,3-bis(diphenylphosphino)propane; OTf=trifluoromethanesulfonate) in good yield. The isolated metallosupramolecular square was characterized by elemental analysis and 1H, 13C, and 31P{1H} NMR and UV/Vis spectroscopy. Furthermore, by means of 1H NMR diffusion-ordered spectroscopy (DOSY) the dimension of this assembly was evaluated by employing a previously reported perylene bisimide ligand and its square assembly as references. The results obtained confirm the square framework of the current assembly. The optical properties of this multichromophore dye assembly were investigated by UV/Vis and steady-state and time-resolved fluorescence spectroscopy. It was revealed that light captured by dimethylaminonaphthalimide antennas could be efficiently transported to the perylene bisimide core by a fluorescence resonance mechanism (energy-transfer efficiency E=95 %), and this resulted in almost exclusive detection of intense perylene bisimide emission, irrespective of the excitation wavelength applied. The present square scaffold containing aminonaphthalimide antenna dyes exhibits more than seven times higher fluorescence quantum yield (Φfl=0.37) than a previously reported pyrene-bearing perylene bisimide-walled square (Φfl=0.05). Thus, this multichromophore square assembly with aminonaphthalimide antenna dyes is an artificial model for the cyclic light-harvesting complexes in purple bacteria.}, author = {You, Chang-Cheng and Hippius, Catharina and Grüne, Matthias and Würthner, Frank}, journal = {Chemistry – A European Journal}, keywords = {myown}, number = 28, pages = {7510–7519}, publisher = {WILEY-VCH Verlag}, title = {Light-Harvesting Metallosupramolecular Squares Composed of Perylene Bisimide Walls and Fluorescent Antenna Dyes}, volume = 12, year = 2006 }

  %0 Journal Article %1 CHEM:CHEM200600413 %A You, Chang-Cheng %A Hippius, Catharina %A Grüne, Matthias %A Würthner, Frank %D 2006 %I WILEY-VCH Verlag %J Chemistry – A European Journal %N 28 %P 7510--7519 %R 10.1002/chem.200600413 %T Light-Harvesting Metallosupramolecular Squares Composed of Perylene Bisimide Walls and Fluorescent Antenna Dyes %U http://dx.doi.org/10.1002/chem.200600413 %V 12 %X The fluorescent dye 4-dimethylamino-1,8-naphthalimide was incorporated at the bay area of N,N′-bispyridyl perylene bisimide to afford a fourfold-functionalized perylene bisimide ligand. Through self-assembly directed by metal-ion coordination, a multichromophore supramolecular entity composed of sixteen dimethylaminonaphthalimide antennas and a perylene bisimide-walled square core was subsequently constructed from this linear ditopic ligand and 90° metal corner [Pd(dppp)](OTf)2 (dppp=1,3-bis(diphenylphosphino)propane; OTf=trifluoromethanesulfonate) in good yield. The isolated metallosupramolecular square was characterized by elemental analysis and 1H, 13C, and 31P1H NMR and UV/Vis spectroscopy. Furthermore, by means of 1H NMR diffusion-ordered spectroscopy (DOSY) the dimension of this assembly was evaluated by employing a previously reported perylene bisimide ligand and its square assembly as references. The results obtained confirm the square framework of the current assembly. The optical properties of this multichromophore dye assembly were investigated by UV/Vis and steady-state and time-resolved fluorescence spectroscopy. It was revealed that light captured by dimethylaminonaphthalimide antennas could be efficiently transported to the perylene bisimide core by a fluorescence resonance mechanism (energy-transfer efficiency E=95 %), and this resulted in almost exclusive detection of intense perylene bisimide emission, irrespective of the excitation wavelength applied. The present square scaffold containing aminonaphthalimide antenna dyes exhibits more than seven times higher fluorescence quantum yield (Φfl=0.37) than a previously reported pyrene-bearing perylene bisimide-walled square (Φfl=0.05). Thus, this multichromophore square assembly with aminonaphthalimide antenna dyes is an artificial model for the cyclic light-harvesting complexes in purple bacteria.
• Thermodynamics of 2,2’:6’,2”-Terpyridine-Metal Ion Complexation. Dobrawa, R.; Ballester, P.; Saha-Möller, C. R.; Würthner, Frank. In American Chemical Society, ACS Symposium Series 928(928), U. S. Schubert; G. R. Newkome; I. Manners (eds.), pp. Chapter 4, 43–. 2006.

  Full paper
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  @article{dobrawa2006thermodynamics, author = {Dobrawa, R. and Ballester, P. and Saha-Möller, C. R. and Würthner, Frank}, editor = {Schubert, U. S. and Newkome, G. R. and Manners, I.}, journal = {American Chemical Society}, keywords = {myown}, note = {Full paper}, number = 928, pages = {Chapter 4, 43–62}, title = {Thermodynamics of 2,2’:6’,2”-Terpyridine-Metal Ion Complexation}, volume = {ACS Symposium Series 928}, year = 2006 }

  %0 Journal Article %1 dobrawa2006thermodynamics %A Dobrawa, R. %A Ballester, P. %A Saha-Möller, C. R. %A Würthner, Frank %D 2006 %E Schubert, U. S. %E Newkome, G. R. %E Manners, I. %J American Chemical Society %N 928 %P Chapter 4, 43–62 %T Thermodynamics of 2,2’:6’,2”-Terpyridine-Metal Ion Complexation %V ACS Symposium Series 928
• One-dimensional luminescent nanoaggregates of perylene bisimides. Würthner, Frank; Chen, Zhijian; Dehm, Volker; Stepanenko, Vladimir. In Chem. Commun., (11), pp. 1188–1190. 2006.
  • [ Abstract ]
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  A new perylene bisimide dye has been synthesized which self-assembles into columnar nanoaggregates and liquid crystalline mesophases with striking photoluminescent properties.

  @article{B517020F, abstract = {A new perylene bisimide dye has been synthesized which self-assembles into columnar nanoaggregates and liquid crystalline mesophases with striking photoluminescent properties.}, author = {Würthner, Frank and Chen, Zhijian and Dehm, Volker and Stepanenko, Vladimir}, journal = {Chem. Commun.}, keywords = {myown}, number = 11, pages = {1188-1190}, publisher = {The Royal Society of Chemistry}, title = {One-dimensional luminescent nanoaggregates of perylene bisimides}, year = 2006 }

  %0 Journal Article %1 B517020F %A Würthner, Frank %A Chen, Zhijian %A Dehm, Volker %A Stepanenko, Vladimir %D 2006 %I The Royal Society of Chemistry %J Chem. Commun. %N 11 %P 1188-1190 %R 10.1039/B517020F %T One-dimensional luminescent nanoaggregates of perylene bisimides %U http://dx.doi.org/10.1039/B517020F %X A new perylene bisimide dye has been synthesized which self-assembles into columnar nanoaggregates and liquid crystalline mesophases with striking photoluminescent properties.
• Supramolecular chemistry at the liquid/solid interface probed by scanning tunnelling microscopy. De Feyter, S.; Miura, A.; Uji-I, H.; Mamdouh, W.; Zhang, J.; Jonkheijm, P.; Schenning, A. P. H. J.; Meijer, E. W.; Chen, Z.; Würthner, F.; Schuurmans, N.; van Esch, J.; Feringa, B. L.; Dulcey, A. E.; Percec, V.; De Schryver, F. C. In Int. J. Nanotechnology, 3(No. 4), pp. 462–479. 2006.
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  @article{defeyter2006supramolecular, author = {De Feyter, S. and Miura, A. and Uji-I, H. and Mamdouh, W. and Zhang, J. and Jonkheijm, P. and Schenning, A. P. H. J. and Meijer, E. W. and Chen, Z. and Würthner, F. and Schuurmans, N. and van Esch, J. and Feringa, B. L. and Dulcey, A. E. and Percec, V. and De Schryver, F. C.}, journal = {Int. J. Nanotechnology}, keywords = {myown}, number = {No. 4}, pages = {462–479}, title = {Supramolecular chemistry at the liquid/solid interface probed by scanning tunnelling microscopy.}, volume = 3, year = 2006 }

  %0 Journal Article %1 defeyter2006supramolecular %A De Feyter, S. %A Miura, A. %A Uji-I, H. %A Mamdouh, W. %A Zhang, J. %A Jonkheijm, P. %A Schenning, A. P. H. J. %A Meijer, E. W. %A Chen, Z. %A Würthner, F. %A Schuurmans, N. %A van Esch, J. %A Feringa, B. L. %A Dulcey, A. E. %A Percec, V. %A De Schryver, F. C. %D 2006 %J Int. J. Nanotechnology %N No. 4 %P 462–479 %T Supramolecular chemistry at the liquid/solid interface probed by scanning tunnelling microscopy. %V 3
• Energy Transfer in Calixarene-Based Cofacial-Positioned Perylene Bisimide Arrays. Hippius, Catharina; Schlosser, Felix; Vysotsky, Myroslav O.; Böhmer, Volker; Würthner, Frank. In J. Am. Chem. Soc., 128(12), pp. 3870–3871. 2006.

  PMID: 16551069
  • [ Abstract ]
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  The synthesis of multichromophoric perylene bisimide-calix[4]arene arrays with up to five perylene units (containing orange, violet, and green perylene bisimide chromophores) and of monochromophoric model compounds was achieved by subsequent imidization of mono-Boc functionalized calix[4]arene linkers with three different types of perylene bisimide dye units. The optical properties of all compounds were studied with UV/vis absorption and steady state and time-resolved fluorescence spectroscopy. Upon excitation of the inner orange dye at 490 nm of array 3, strong fluorescence emission of the outer green perylene bisimide (PBI) chromophore at 744 nm is observed. The fluorescence excitation spectra of compounds 3 and 4 (λdet = 850 nm) show all absorption bands of the parent chromophores (e.g., all perylene units contribute to the emission from S1 state of the green PBI). Thus, the fluorescence emission and excitation spectra as well as time-resolved data of fluorescence lifetimes in the absence (τD = 5.1 ns) and in the presence of an acceptor (τDA = 0.8 ns) suggest efficient energy transfer processes between the perylene bisimide dye units. For the bichromophoric array 4, the energy transfer rate is calculated to a value of 1.05 × 109 s-1. These results demonstrate highly efficient energy transfer in cofacially assembled dye arrays.

  @article{doi:10.1021/ja058007+, abstract = {The synthesis of multichromophoric perylene bisimide-calix[4]arene arrays with up to five perylene units (containing orange, violet, and green perylene bisimide chromophores) and of monochromophoric model compounds was achieved by subsequent imidization of mono-Boc functionalized calix[4]arene linkers with three different types of perylene bisimide dye units. The optical properties of all compounds were studied with UV/vis absorption and steady state and time-resolved fluorescence spectroscopy. Upon excitation of the inner orange dye at 490 nm of array 3, strong fluorescence emission of the outer green perylene bisimide (PBI) chromophore at 744 nm is observed. The fluorescence excitation spectra of compounds 3 and 4 (λdet = 850 nm) show all absorption bands of the parent chromophores (e.g., all perylene units contribute to the emission from S1 state of the green PBI). Thus, the fluorescence emission and excitation spectra as well as time-resolved data of fluorescence lifetimes in the absence (τD = 5.1 ns) and in the presence of an acceptor (τDA = 0.8 ns) suggest efficient energy transfer processes between the perylene bisimide dye units. For the bichromophoric array 4, the energy transfer rate is calculated to a value of 1.05 × 109 s-1. These results demonstrate highly efficient energy transfer in cofacially assembled dye arrays.}, author = {Hippius, Catharina and Schlosser, Felix and Vysotsky, Myroslav O. and Böhmer, Volker and Würthner, Frank}, journal = {J. Am. Chem. Soc.}, keywords = {myown}, note = {PMID: 16551069}, number = 12, pages = {3870-3871}, title = {Energy Transfer in Calixarene-Based Cofacial-Positioned Perylene Bisimide Arrays}, volume = 128, year = 2006 }

  %0 Journal Article %1 doi:10.1021/ja058007+ %A Hippius, Catharina %A Schlosser, Felix %A Vysotsky, Myroslav O. %A Böhmer, Volker %A Würthner, Frank %D 2006 %J J. Am. Chem. Soc. %N 12 %P 3870-3871 %R 10.1021/ja058007+ %T Energy Transfer in Calixarene-Based Cofacial-Positioned Perylene Bisimide Arrays %U http://dx.doi.org/10.1021/ja058007 %V 128 %X The synthesis of multichromophoric perylene bisimide-calix[4]arene arrays with up to five perylene units (containing orange, violet, and green perylene bisimide chromophores) and of monochromophoric model compounds was achieved by subsequent imidization of mono-Boc functionalized calix[4]arene linkers with three different types of perylene bisimide dye units. The optical properties of all compounds were studied with UV/vis absorption and steady state and time-resolved fluorescence spectroscopy. Upon excitation of the inner orange dye at 490 nm of array 3, strong fluorescence emission of the outer green perylene bisimide (PBI) chromophore at 744 nm is observed. The fluorescence excitation spectra of compounds 3 and 4 (λdet = 850 nm) show all absorption bands of the parent chromophores (e.g., all perylene units contribute to the emission from S1 state of the green PBI). Thus, the fluorescence emission and excitation spectra as well as time-resolved data of fluorescence lifetimes in the absence (τD = 5.1 ns) and in the presence of an acceptor (τDA = 0.8 ns) suggest efficient energy transfer processes between the perylene bisimide dye units. For the bichromophoric array 4, the energy transfer rate is calculated to a value of 1.05 × 109 s-1. These results demonstrate highly efficient energy transfer in cofacially assembled dye arrays.
• Control of Ambipolar Thin Film Architectures by Co-Self-Assembling Oligo(p-phenylenevinylene)s and Perylene Bisimides. Jonkheijm, Pascal; Stutzmann, Natalie; Chen, Zhijian; de Leeuw, Dago M.; Meijer, E. W.; Schenning, Albertus P. H. J.; Würthner, Frank. In J. Am. Chem. Soc., 128(29), pp. 9535–9540. 2006.

  PMID: 16848491
  • [ Abstract ]
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  Control of thin film morphology by self-assembly of, respectively, p-type oligo(p-phenylenevinylene)s (OPV)s and n-type perylenebisimides (PBI)s in solution prior to processing, results in film architectures consisting of uniform rodlike domains as shown by atomic force microscopy. Such films from self-assembled molecules show superior charge-carrier mobility in comparison with films processed from molecular dissolved molecules. Moreover, connecting the OPV and PBI building blocks through hydrogen-bonding interactions creates dyad complexes that cofacially stack in apolar solvents. Ambipolar field-effect transistors constructed from these dyad complexes show two independent pathways for charge transport. In strong contrast, processing of OPV and PBI, that are not connected by hydrogen bonds, form charge transfer donor−acceptor complexes that show no mobility in field-effect transistors presumably due to an unfavorable supramolecular organization.

  @article{doi:10.1021/ja061966z, abstract = {Control of thin film morphology by self-assembly of, respectively, p-type oligo(p-phenylenevinylene)s (OPV)s and n-type perylenebisimides (PBI)s in solution prior to processing, results in film architectures consisting of uniform rodlike domains as shown by atomic force microscopy. Such films from self-assembled molecules show superior charge-carrier mobility in comparison with films processed from molecular dissolved molecules. Moreover, connecting the OPV and PBI building blocks through hydrogen-bonding interactions creates dyad complexes that cofacially stack in apolar solvents. Ambipolar field-effect transistors constructed from these dyad complexes show two independent pathways for charge transport. In strong contrast, processing of OPV and PBI, that are not connected by hydrogen bonds, form charge transfer donor−acceptor complexes that show no mobility in field-effect transistors presumably due to an unfavorable supramolecular organization.}, author = {Jonkheijm, Pascal and Stutzmann, Natalie and Chen, Zhijian and de Leeuw, Dago M. and Meijer, E. W. and Schenning, Albertus P. H. J. and Würthner, Frank}, journal = {J. Am. Chem. Soc.}, keywords = {myown}, note = {PMID: 16848491}, number = 29, pages = {9535-9540}, title = {Control of Ambipolar Thin Film Architectures by Co-Self-Assembling Oligo(p-phenylenevinylene)s and Perylene Bisimides}, volume = 128, year = 2006 }

  %0 Journal Article %1 doi:10.1021/ja061966z %A Jonkheijm, Pascal %A Stutzmann, Natalie %A Chen, Zhijian %A de Leeuw, Dago M. %A Meijer, E. W. %A Schenning, Albertus P. H. J. %A Würthner, Frank %D 2006 %J J. Am. Chem. Soc. %N 29 %P 9535-9540 %R 10.1021/ja061966z %T Control of Ambipolar Thin Film Architectures by Co-Self-Assembling Oligo(p-phenylenevinylene)s and Perylene Bisimides %U http://dx.doi.org/10.1021/ja061966z %V 128 %X Control of thin film morphology by self-assembly of, respectively, p-type oligo(p-phenylenevinylene)s (OPV)s and n-type perylenebisimides (PBI)s in solution prior to processing, results in film architectures consisting of uniform rodlike domains as shown by atomic force microscopy. Such films from self-assembled molecules show superior charge-carrier mobility in comparison with films processed from molecular dissolved molecules. Moreover, connecting the OPV and PBI building blocks through hydrogen-bonding interactions creates dyad complexes that cofacially stack in apolar solvents. Ambipolar field-effect transistors constructed from these dyad complexes show two independent pathways for charge transport. In strong contrast, processing of OPV and PBI, that are not connected by hydrogen bonds, form charge transfer donor−acceptor complexes that show no mobility in field-effect transistors presumably due to an unfavorable supramolecular organization.

• Fluorescent Supramolecular Polymers:  Metal Directed Self-Assembly of Perylene Bisimide Building Blocks. Dobrawa, Rainer; Lysetska, Marina; Ballester, Pablo; Grüne, Matthias; Würthner, Frank. In Macromolecules, 38(4), pp. 1315–1325. 2005.
  • [ Abstract ]
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  Complexation properties of 2,2‘:6‘,2‘ ‘-terpyridine (tpy) have been studied with a series of first row transition metal ions by UV−vis, 1H NMR, and isothermal titration calorimetry, and ΔH values for the tpy complexation processes have been determined. These studies reveal that terpyridine−Zn2+ complex constitutes an ideal supramolecular building block characterized by thermodynamically stable and kinetically labile coordination bonding. Thus, at room-temperature, perylene bisimide fluorophores equipped with one or two terpyridine functionalities formed coordination dimers and polymers, respectively, upon addition of Zn2+ metal ions. The reversible formation of coordination dimers and polymers has been established by 1H NMR and additionally by DOSY NMR and fluorescence anisotropy measurements. The optical properties of dimeric and polymeric complexes have been investigated by UV−vis and fluorescence spectroscopy which prove that the Zn2+ coordination to the terpyridine unit does not effect the advantageous fluorescence properties of perylene bisimide moieties. Coordination polymer strands can be visualized by atomic force microscopy (AFM), which also reveals the formation of a monolayer film at higher concentration. The average polymer length has been determined by AFM to 15 repeat units, which correlates well with the value estimated by 1H NMR to >10 repeat units.

  @article{doi:10.1021/ma047737j, abstract = {Complexation properties of 2,2‘:6‘,2‘ ‘-terpyridine (tpy) have been studied with a series of first row transition metal ions by UV−vis, 1H NMR, and isothermal titration calorimetry, and ΔH values for the tpy complexation processes have been determined. These studies reveal that terpyridine−Zn2+ complex constitutes an ideal supramolecular building block characterized by thermodynamically stable and kinetically labile coordination bonding. Thus, at room-temperature, perylene bisimide fluorophores equipped with one or two terpyridine functionalities formed coordination dimers and polymers, respectively, upon addition of Zn2+ metal ions. The reversible formation of coordination dimers and polymers has been established by 1H NMR and additionally by DOSY NMR and fluorescence anisotropy measurements. The optical properties of dimeric and polymeric complexes have been investigated by UV−vis and fluorescence spectroscopy which prove that the Zn2+ coordination to the terpyridine unit does not effect the advantageous fluorescence properties of perylene bisimide moieties. Coordination polymer strands can be visualized by atomic force microscopy (AFM), which also reveals the formation of a monolayer film at higher concentration. The average polymer length has been determined by AFM to 15 repeat units, which correlates well with the value estimated by 1H NMR to >10 repeat units.}, author = {Dobrawa, Rainer and Lysetska, Marina and Ballester, Pablo and Grüne, Matthias and Würthner, Frank}, journal = {Macromolecules}, keywords = {myown}, number = 4, pages = {1315-1325}, title = {Fluorescent Supramolecular Polymers:  Metal Directed Self-Assembly of Perylene Bisimide Building Blocks}, volume = 38, year = 2005 }

  %0 Journal Article %1 doi:10.1021/ma047737j %A Dobrawa, Rainer %A Lysetska, Marina %A Ballester, Pablo %A Grüne, Matthias %A Würthner, Frank %D 2005 %J Macromolecules %N 4 %P 1315-1325 %R 10.1021/ma047737j %T Fluorescent Supramolecular Polymers:  Metal Directed Self-Assembly of Perylene Bisimide Building Blocks %U http://dx.doi.org/10.1021/ma047737j %V 38 %X Complexation properties of 2,2‘:6‘,2‘ ‘-terpyridine (tpy) have been studied with a series of first row transition metal ions by UV−vis, 1H NMR, and isothermal titration calorimetry, and ΔH values for the tpy complexation processes have been determined. These studies reveal that terpyridine−Zn2+ complex constitutes an ideal supramolecular building block characterized by thermodynamically stable and kinetically labile coordination bonding. Thus, at room-temperature, perylene bisimide fluorophores equipped with one or two terpyridine functionalities formed coordination dimers and polymers, respectively, upon addition of Zn2+ metal ions. The reversible formation of coordination dimers and polymers has been established by 1H NMR and additionally by DOSY NMR and fluorescence anisotropy measurements. The optical properties of dimeric and polymeric complexes have been investigated by UV−vis and fluorescence spectroscopy which prove that the Zn2+ coordination to the terpyridine unit does not effect the advantageous fluorescence properties of perylene bisimide moieties. Coordination polymer strands can be visualized by atomic force microscopy (AFM), which also reveals the formation of a monolayer film at higher concentration. The average polymer length has been determined by AFM to 15 repeat units, which correlates well with the value estimated by 1H NMR to >10 repeat units.
• Two-Dimensional Self-Assembly into Multicomponent Hydrogen-Bonded Nanostructures. De Feyter, Steven; Miura, Atsushi; Yao, Sheng; Chen, Zhijian; Würthner, Frank; Jonkheijm, Pascal; Schenning, Albertus P. H. J.; Meijer, E. W.; De Schryver, Frans C. In Nano Letters, 5(1), pp. 77–81. 2005.

  PMID: 15792416
  • [ Abstract ]
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  By means of scanning tunneling microscopy, we have explored the two-dimensional self-assembly of functional bicomponent hydrogen-bonding dye systems, leading to well-defined patterns, different from those of the individual components, and providing design rules to immobilize multicomponent systems at the liquid−solid interface.

  @article{doi:10.1021/nl048360y, abstract = {By means of scanning tunneling microscopy, we have explored the two-dimensional self-assembly of functional bicomponent hydrogen-bonding dye systems, leading to well-defined patterns, different from those of the individual components, and providing design rules to immobilize multicomponent systems at the liquid−solid interface.}, author = {De Feyter, Steven and Miura, Atsushi and Yao, Sheng and Chen, Zhijian and Würthner, Frank and Jonkheijm, Pascal and Schenning, Albertus P. H. J. and Meijer, E. W. and De Schryver, Frans C.}, journal = {Nano Letters}, keywords = {myown}, note = {PMID: 15792416}, number = 1, pages = {77-81}, title = {Two-Dimensional Self-Assembly into Multicomponent Hydrogen-Bonded Nanostructures}, volume = 5, year = 2005 }

  %0 Journal Article %1 doi:10.1021/nl048360y %A De Feyter, Steven %A Miura, Atsushi %A Yao, Sheng %A Chen, Zhijian %A Würthner, Frank %A Jonkheijm, Pascal %A Schenning, Albertus P. H. J. %A Meijer, E. W. %A De Schryver, Frans C. %D 2005 %J Nano Letters %N 1 %P 77-81 %R 10.1021/nl048360y %T Two-Dimensional Self-Assembly into Multicomponent Hydrogen-Bonded Nanostructures %U http://dx.doi.org/10.1021/nl048360y %V 5 %X By means of scanning tunneling microscopy, we have explored the two-dimensional self-assembly of functional bicomponent hydrogen-bonding dye systems, leading to well-defined patterns, different from those of the individual components, and providing design rules to immobilize multicomponent systems at the liquid−solid interface.
• Metallosupramolecular Dye Assemblies. You, Chang-Cheng; Dobrawa, Rainer; Saha-Möller, Chantu R.; Würthner, Frank. In Supermolecular Dye Chemistry, F. Würthner (ed.), pp. 39–82. 2005.
  • [ Abstract ]
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  Metallosupramolecular assemblies of dyes are of increasing interest as model systems for natural light harvesting and photosynthetic complexes as well as for potential applications in solar energy conversion, photonics and molecular electronics. Considerable efforts have been made in the past years to design novel metallosupramolecular dye architectures for such applications. Often in combination with other noncovalent interactions like hydrogen-bonding and $\pi$--$\pi$-stacking, metal-ion coordination has been utilized to achieve self-organization of dye building blocks into elaborate architectures with interesting optical and photophysical properties. Diverse metallosupramolecular dye assemblies -- macrocycles, polyhedra, polymers and dendrimers -- have been constructed in recent years by the metal-coordination approach. Here we review the recent advances in metallosupramolecular dye assemblies with particular attention to their thermodynamic stability and photophysical functionality. Emphasis is given to metal-ion mediated self-organization of porphyrin, metalloporphyrin and perylene bisimide dyes.

  @inbook{You2005, abstract = {Metallosupramolecular assemblies of dyes are of increasing interest as model systems for natural light harvesting and photosynthetic complexes as well as for potential applications in solar energy conversion, photonics and molecular electronics. Considerable efforts have been made in the past years to design novel metallosupramolecular dye architectures for such applications. Often in combination with other noncovalent interactions like hydrogen-bonding and $\pi$–$\pi$-stacking, metal-ion coordination has been utilized to achieve self-organization of dye building blocks into elaborate architectures with interesting optical and photophysical properties. Diverse metallosupramolecular dye assemblies – macrocycles, polyhedra, polymers and dendrimers – have been constructed in recent years by the metal-coordination approach. Here we review the recent advances in metallosupramolecular dye assemblies with particular attention to their thermodynamic stability and photophysical functionality. Emphasis is given to metal-ion mediated self-organization of porphyrin, metalloporphyrin and perylene bisimide dyes.}, address = {Berlin, Heidelberg}, author = {You, Chang-Cheng and Dobrawa, Rainer and Saha-Möller, Chantu R. and Würthner, Frank}, booktitle = {Supermolecular Dye Chemistry}, editor = {Würthner, Frank}, keywords = {myown}, pages = {39–82}, publisher = {Springer Berlin Heidelberg}, title = {Metallosupramolecular Dye Assemblies}, year = 2005 }

  %0 Book Section %1 You2005 %A You, Chang-Cheng %A Dobrawa, Rainer %A Saha-Möller, Chantu R. %A Würthner, Frank %B Supermolecular Dye Chemistry %C Berlin, Heidelberg %D 2005 %E Würthner, Frank %I Springer Berlin Heidelberg %P 39--82 %R 10.1007/b136668 %T Metallosupramolecular Dye Assemblies %U https://doi.org/10.1007/b136668 %X Metallosupramolecular assemblies of dyes are of increasing interest as model systems for natural light harvesting and photosynthetic complexes as well as for potential applications in solar energy conversion, photonics and molecular electronics. Considerable efforts have been made in the past years to design novel metallosupramolecular dye architectures for such applications. Often in combination with other noncovalent interactions like hydrogen-bonding and $\pi$--$\pi$-stacking, metal-ion coordination has been utilized to achieve self-organization of dye building blocks into elaborate architectures with interesting optical and photophysical properties. Diverse metallosupramolecular dye assemblies -- macrocycles, polyhedra, polymers and dendrimers -- have been constructed in recent years by the metal-coordination approach. Here we review the recent advances in metallosupramolecular dye assemblies with particular attention to their thermodynamic stability and photophysical functionality. Emphasis is given to metal-ion mediated self-organization of porphyrin, metalloporphyrin and perylene bisimide dyes. %@ 978-3-540-31458-5
• Perylene Bisimide Based Macrocycles: Effective Probes for the Assessment of Conformational Effects on Optical Properties. Osswald, Peter; Leusser, Dirk; Stalke, Dietmar; Würthner, Frank. In Angew. Chem. Int. Ed., 44(2), pp. 250–253. 2005.
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  @article{ANIE:ANIE200461585, author = {Osswald, Peter and Leusser, Dirk and Stalke, Dietmar and Würthner, Frank}, journal = {Angew. Chem. Int. Ed.}, keywords = {myown}, number = 2, pages = {250–253}, publisher = {WILEY-VCH Verlag}, title = {Perylene Bisimide Based Macrocycles: Effective Probes for the Assessment of Conformational Effects on Optical Properties}, volume = 44, year = 2005 }

  %0 Journal Article %1 ANIE:ANIE200461585 %A Osswald, Peter %A Leusser, Dirk %A Stalke, Dietmar %A Würthner, Frank %D 2005 %I WILEY-VCH Verlag %J Angew. Chem. Int. Ed. %N 2 %P 250--253 %R 10.1002/anie.200461585 %T Perylene Bisimide Based Macrocycles: Effective Probes for the Assessment of Conformational Effects on Optical Properties %U http://dx.doi.org/10.1002/anie.200461585 %V 44
• DNA-Binding Fourfold Spermine Functionalized Perylene Bisimide Dye. Krauß, Stefanie; Lysetska, Marina; Würthner, Frank. In Letters in Organic Chemistry, 2(4), pp. 349–353. 2005.
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  A spermine functionalized perylene bisimide dye has been synthesized which is highly water soluble at neutral pH and binds effectively to DNA through electrostatic interactions as confirmed by fluorescence and AFM studies.

  @article{krau2005dnabinding, abstract = {A spermine functionalized perylene bisimide dye has been synthesized which is highly water soluble at neutral pH and binds effectively to DNA through electrostatic interactions as confirmed by fluorescence and AFM studies.}, author = {Krauß, Stefanie and Lysetska, Marina and Würthner, Frank}, journal = {Letters in Organic Chemistry}, keywords = {dye}, number = 4, pages = {349 - 353}, title = {DNA-Binding Fourfold Spermine Functionalized Perylene Bisimide Dye}, volume = 2, year = 2005 }

  %0 Journal Article %1 krau2005dnabinding %A Krauß, Stefanie %A Lysetska, Marina %A Würthner, Frank %D 2005 %J Letters in Organic Chemistry %N 4 %P 349 - 353 %R 10.2174/1570178054038858 %T DNA-Binding Fourfold Spermine Functionalized Perylene Bisimide Dye %U https://doi.org/10.2174/1570178054038858 %V 2 %X A spermine functionalized perylene bisimide dye has been synthesized which is highly water soluble at neutral pH and binds effectively to DNA through electrostatic interactions as confirmed by fluorescence and AFM studies.
• Scanning Tunneling Microscopy and Spectroscopy of Donor–Acceptor–Donor Triads at the Liquid/Solid Interface. Uji i, Hiroshi; Miura, Atsushi; Schenning, Albert; Meijer, E. W.; Chen, Zhijian; Würthner, Frank; De Schryver, Frans C.; Van der Auweraer, Mark; De Feyter, Steven. In ChemPhysChem, 6(11), pp. 2389–2395. 2005.
  • [ Abstract ]
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  By means of scanning tunneling microscopy (STM), the self-assembly of two organic donor–acceptor–donor triads (donor=oligo(p-phenylene vinylene) (OPV); acceptor=perylene diimide (PDI)) and their mixtures has been investigated at the liquid/solid interface. Both triads differ in the nature of the substituents and, therefore, in the redox properties of the central perylene diimide unit (H or Cl). Thanks to the submolecular resolution, the distinct electronic properties of the units, within a triad and between the two triads, are reflected by the relative STM contrast in the bias-dependent imaging experiments. Moreover, scanning tunneling spectroscopy reveals an inverse rectifying behavior of the OPV and H-substituted PDI units, which is discussed in the framework of quasi-resonant tunneling. A striking difference is observed for the Cl-substituted triad.

  @article{CPHC:CPHC200500241, abstract = {By means of scanning tunneling microscopy (STM), the self-assembly of two organic donor–acceptor–donor triads (donor=oligo(p-phenylene vinylene) (OPV); acceptor=perylene diimide (PDI)) and their mixtures has been investigated at the liquid/solid interface. Both triads differ in the nature of the substituents and, therefore, in the redox properties of the central perylene diimide unit (H or Cl). Thanks to the submolecular resolution, the distinct electronic properties of the units, within a triad and between the two triads, are reflected by the relative STM contrast in the bias-dependent imaging experiments. Moreover, scanning tunneling spectroscopy reveals an inverse rectifying behavior of the OPV and H-substituted PDI units, which is discussed in the framework of quasi-resonant tunneling. A striking difference is observed for the Cl-substituted triad.}, author = {Uji i, Hiroshi and Miura, Atsushi and Schenning, Albert and Meijer, E. W. and Chen, Zhijian and Würthner, Frank and De Schryver, Frans C. and Van der Auweraer, Mark and De Feyter, Steven}, journal = {ChemPhysChem}, keywords = {myown}, number = 11, pages = {2389–2395}, publisher = {WILEY-VCH Verlag}, title = {Scanning Tunneling Microscopy and Spectroscopy of Donor–Acceptor–Donor Triads at the Liquid/Solid Interface}, volume = 6, year = 2005 }

  %0 Journal Article %1 CPHC:CPHC200500241 %A Uji i, Hiroshi %A Miura, Atsushi %A Schenning, Albert %A Meijer, E. W. %A Chen, Zhijian %A Würthner, Frank %A De Schryver, Frans C. %A Van der Auweraer, Mark %A De Feyter, Steven %D 2005 %I WILEY-VCH Verlag %J ChemPhysChem %N 11 %P 2389--2395 %R 10.1002/cphc.200500241 %T Scanning Tunneling Microscopy and Spectroscopy of Donor–Acceptor–Donor Triads at the Liquid/Solid Interface %U http://dx.doi.org/10.1002/cphc.200500241 %V 6 %X By means of scanning tunneling microscopy (STM), the self-assembly of two organic donor–acceptor–donor triads (donor=oligo(p-phenylene vinylene) (OPV); acceptor=perylene diimide (PDI)) and their mixtures has been investigated at the liquid/solid interface. Both triads differ in the nature of the substituents and, therefore, in the redox properties of the central perylene diimide unit (H or Cl). Thanks to the submolecular resolution, the distinct electronic properties of the units, within a triad and between the two triads, are reflected by the relative STM contrast in the bias-dependent imaging experiments. Moreover, scanning tunneling spectroscopy reveals an inverse rectifying behavior of the OPV and H-substituted PDI units, which is discussed in the framework of quasi-resonant tunneling. A striking difference is observed for the Cl-substituted triad.
• Reversible Self-Organization of Semisynthetic Zinc Chlorins into Well-Defined Rod Antennae. Huber, Valerie; Katterle, Martin; Lysetska, Marina; Würthner, Frank. In Angew. Chem. Int. Ed., 44(20), pp. 3147–3151. 2005.
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  @article{ANIE:ANIE200462762, author = {Huber, Valerie and Katterle, Martin and Lysetska, Marina and Würthner, Frank}, journal = {Angew. Chem. Int. Ed.}, keywords = {myown}, number = 20, pages = {3147–3151}, publisher = {WILEY-VCH Verlag}, title = {Reversible Self-Organization of Semisynthetic Zinc Chlorins into Well-Defined Rod Antennae}, volume = 44, year = 2005 }

  %0 Journal Article %1 ANIE:ANIE200462762 %A Huber, Valerie %A Katterle, Martin %A Lysetska, Marina %A Würthner, Frank %D 2005 %I WILEY-VCH Verlag %J Angew. Chem. Int. Ed. %N 20 %P 3147--3151 %R 10.1002/anie.200462762 %T Reversible Self-Organization of Semisynthetic Zinc Chlorins into Well-Defined Rod Antennae %U http://dx.doi.org/10.1002/anie.200462762 %V 44
• Solvent-Dependent Vibrational Frequencies and Reorganization Energies of Two Merocyanine Chromophores. Leng, Weinan; Würthner, Frank; Kelley, Anne Myers. In J. Phys. Chem. A, 109(8), pp. 1570–1575. 2005.

  PMID: 16833479
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  Absorption and resonance Raman spectra have been measured over a wide range of solvents for two merocyanine dyes containing the indoline (“Fischer” base) electron donor group with different accepting groups. One appears to be near the cyanine limit (equal contributions of the neutral and zwitterionic resonance forms to both ground- and excited-state structures) based on electrooptic absorption data showing a very small dipole moment change upon electronic excitation. The resonance Raman spectra of both molecules show significant frequency shifts and intensity redistributions that evolve monotonically with increasing solvent polarity and are consistent with increasing zwitterionic character of the ground-state structure. The vibrational reorganization energies of both molecules, obtained by simulating the absorption band shapes, are smaller in polar solvents than in nonpolar or weakly polar ones, consistent with a more cyanine-like structure at higher solvent polarities. However, the vibrational reorganization energies of both molecules exceed 700 cm-1 in all solvents, larger than in many true cyanine dyes, and the optical absorption maxima do not correlate well with either solvent polarity or vibrational reorganization energy. This indicates some limitations to the structural conclusions that can be reached from the two-state model for π-conjugated donor−acceptor systems.

  @article{doi:10.1021/jp045145x, abstract = {Absorption and resonance Raman spectra have been measured over a wide range of solvents for two merocyanine dyes containing the indoline (“Fischer” base) electron donor group with different accepting groups. One appears to be near the cyanine limit (equal contributions of the neutral and zwitterionic resonance forms to both ground- and excited-state structures) based on electrooptic absorption data showing a very small dipole moment change upon electronic excitation. The resonance Raman spectra of both molecules show significant frequency shifts and intensity redistributions that evolve monotonically with increasing solvent polarity and are consistent with increasing zwitterionic character of the ground-state structure. The vibrational reorganization energies of both molecules, obtained by simulating the absorption band shapes, are smaller in polar solvents than in nonpolar or weakly polar ones, consistent with a more cyanine-like structure at higher solvent polarities. However, the vibrational reorganization energies of both molecules exceed 700 cm-1 in all solvents, larger than in many true cyanine dyes, and the optical absorption maxima do not correlate well with either solvent polarity or vibrational reorganization energy. This indicates some limitations to the structural conclusions that can be reached from the two-state model for π-conjugated donor−acceptor systems.}, author = {Leng, Weinan and Würthner, Frank and Kelley, Anne Myers}, journal = {J. Phys. Chem. A}, keywords = {myown}, note = {PMID: 16833479}, number = 8, pages = {1570-1575}, title = {Solvent-Dependent Vibrational Frequencies and Reorganization Energies of Two Merocyanine Chromophores}, volume = 109, year = 2005 }

  %0 Journal Article %1 doi:10.1021/jp045145x %A Leng, Weinan %A Würthner, Frank %A Kelley, Anne Myers %D 2005 %J J. Phys. Chem. A %N 8 %P 1570-1575 %R 10.1021/jp045145x %T Solvent-Dependent Vibrational Frequencies and Reorganization Energies of Two Merocyanine Chromophores %U http://dx.doi.org/10.1021/jp045145x %V 109 %X Absorption and resonance Raman spectra have been measured over a wide range of solvents for two merocyanine dyes containing the indoline (“Fischer” base) electron donor group with different accepting groups. One appears to be near the cyanine limit (equal contributions of the neutral and zwitterionic resonance forms to both ground- and excited-state structures) based on electrooptic absorption data showing a very small dipole moment change upon electronic excitation. The resonance Raman spectra of both molecules show significant frequency shifts and intensity redistributions that evolve monotonically with increasing solvent polarity and are consistent with increasing zwitterionic character of the ground-state structure. The vibrational reorganization energies of both molecules, obtained by simulating the absorption band shapes, are smaller in polar solvents than in nonpolar or weakly polar ones, consistent with a more cyanine-like structure at higher solvent polarities. However, the vibrational reorganization energies of both molecules exceed 700 cm-1 in all solvents, larger than in many true cyanine dyes, and the optical absorption maxima do not correlate well with either solvent polarity or vibrational reorganization energy. This indicates some limitations to the structural conclusions that can be reached from the two-state model for π-conjugated donor−acceptor systems.
• Wavelength-Dependent Electron and Energy Transfer Pathways in a Side-to-Face Ruthenium Porphyrin/Perylene Bisimide Assembly. Prodi, Anna; Chiorboli, Claudio; Scandola, Franco; Iengo, Elisabetta; Alessio, Enzo; Dobrawa, Rainer; Würthner, Frank. In J. Am. Chem. Soc., 127(5), pp. 1454–1462. 2005.

  PMID: 15686378
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  A new side-to-face supramolecular array of chromophores, where a pyridyl-substituted perylene bisimide dye axially binds to two ruthenium porphyrin fragments, has been prepared by self-assembly. The array is formulated as DPyPBI[Ru(TPP)(CO)]2, where DPyPBI = N,N‘-di(4-pyridyl)-1,6,7,12-tetra(4-tert-butylphenoxy)perylene-3,4:9,10-tetracarboxylic acid bisimide and TPP = 5,10,15,20-tetraphenylporphyrin. The photophysical behavior of DPyPBI[Ru(TPP)(CO)]2 has been studied by fast (nanoseconds) and ultrafast (femtoseconds) time-resolved techniques. The observed behavior sharply changes with excitation wavelength, depending on whether the DPyPBI or Ru(TPP)(CO) units are excited. After DPyPBI excitation, the strong fluorescence typical of this unit is completely quenched, and time-resolved spectroscopy reveals the occurrence of photoinduced electron transfer from the ruthenium porphyrin to the perylene bisimide dye (τ = 5.6 ps) followed by charge recombination (τ = 270 ps). Upon excitation of the Ru(TPP)(CO) fragments, on the other hand, ultrafast (τ < 1 ps) intersystem crossing is followed by triplet energy transfer from the ruthenium porphyrin to the perylene bisimide dye (τ = 720 ps). The perylene-based triplet state decays to the ground state on a longer time scale (τ = 9.8 μs). The photophysics of this supramolecular array provides remarkable examples of (i) wavelength-dependent behavior (a small change in excitation wavelength causes a sharp switch from electron to energy transfer) and (ii) intramolecular sensitization (the triplet state of the perylene bisimide, inaccessible in the free dye, is efficiently populated in the array).

  @article{doi:10.1021/ja045379u, abstract = {A new side-to-face supramolecular array of chromophores, where a pyridyl-substituted perylene bisimide dye axially binds to two ruthenium porphyrin fragments, has been prepared by self-assembly. The array is formulated as DPyPBI[Ru(TPP)(CO)]2, where DPyPBI = N,N‘-di(4-pyridyl)-1,6,7,12-tetra(4-tert-butylphenoxy)perylene-3,4:9,10-tetracarboxylic acid bisimide and TPP = 5,10,15,20-tetraphenylporphyrin. The photophysical behavior of DPyPBI[Ru(TPP)(CO)]2 has been studied by fast (nanoseconds) and ultrafast (femtoseconds) time-resolved techniques. The observed behavior sharply changes with excitation wavelength, depending on whether the DPyPBI or Ru(TPP)(CO) units are excited. After DPyPBI excitation, the strong fluorescence typical of this unit is completely quenched, and time-resolved spectroscopy reveals the occurrence of photoinduced electron transfer from the ruthenium porphyrin to the perylene bisimide dye (τ = 5.6 ps) followed by charge recombination (τ = 270 ps). Upon excitation of the Ru(TPP)(CO) fragments, on the other hand, ultrafast (τ < 1 ps) intersystem crossing is followed by triplet energy transfer from the ruthenium porphyrin to the perylene bisimide dye (τ = 720 ps). The perylene-based triplet state decays to the ground state on a longer time scale (τ = 9.8 μs). The photophysics of this supramolecular array provides remarkable examples of (i) wavelength-dependent behavior (a small change in excitation wavelength causes a sharp switch from electron to energy transfer) and (ii) intramolecular sensitization (the triplet state of the perylene bisimide, inaccessible in the free dye, is efficiently populated in the array).}, author = {Prodi, Anna and Chiorboli, Claudio and Scandola, Franco and Iengo, Elisabetta and Alessio, Enzo and Dobrawa, Rainer and Würthner, Frank}, journal = {J. Am. Chem. Soc.}, keywords = {myown}, note = {PMID: 15686378}, number = 5, pages = {1454-1462}, title = {Wavelength-Dependent Electron and Energy Transfer Pathways in a Side-to-Face Ruthenium Porphyrin/Perylene Bisimide Assembly}, volume = 127, year = 2005 }

  %0 Journal Article %1 doi:10.1021/ja045379u %A Prodi, Anna %A Chiorboli, Claudio %A Scandola, Franco %A Iengo, Elisabetta %A Alessio, Enzo %A Dobrawa, Rainer %A Würthner, Frank %D 2005 %J J. Am. Chem. Soc. %N 5 %P 1454-1462 %R 10.1021/ja045379u %T Wavelength-Dependent Electron and Energy Transfer Pathways in a Side-to-Face Ruthenium Porphyrin/Perylene Bisimide Assembly %U http://dx.doi.org/10.1021/ja045379u %V 127 %X A new side-to-face supramolecular array of chromophores, where a pyridyl-substituted perylene bisimide dye axially binds to two ruthenium porphyrin fragments, has been prepared by self-assembly. The array is formulated as DPyPBI[Ru(TPP)(CO)]2, where DPyPBI = N,N‘-di(4-pyridyl)-1,6,7,12-tetra(4-tert-butylphenoxy)perylene-3,4:9,10-tetracarboxylic acid bisimide and TPP = 5,10,15,20-tetraphenylporphyrin. The photophysical behavior of DPyPBI[Ru(TPP)(CO)]2 has been studied by fast (nanoseconds) and ultrafast (femtoseconds) time-resolved techniques. The observed behavior sharply changes with excitation wavelength, depending on whether the DPyPBI or Ru(TPP)(CO) units are excited. After DPyPBI excitation, the strong fluorescence typical of this unit is completely quenched, and time-resolved spectroscopy reveals the occurrence of photoinduced electron transfer from the ruthenium porphyrin to the perylene bisimide dye (τ = 5.6 ps) followed by charge recombination (τ = 270 ps). Upon excitation of the Ru(TPP)(CO) fragments, on the other hand, ultrafast (τ < 1 ps) intersystem crossing is followed by triplet energy transfer from the ruthenium porphyrin to the perylene bisimide dye (τ = 720 ps). The perylene-based triplet state decays to the ground state on a longer time scale (τ = 9.8 μs). The photophysics of this supramolecular array provides remarkable examples of (i) wavelength-dependent behavior (a small change in excitation wavelength causes a sharp switch from electron to energy transfer) and (ii) intramolecular sensitization (the triplet state of the perylene bisimide, inaccessible in the free dye, is efficiently populated in the array).
• Photophysical Properties of a Tetraphenoxy-Substituted Perylene Bisimide Derivative Characterized by Single-Molecule Spectroscopy. Lang, Erwin; Würthner, Frank; Köhler, Jürgen. In ChemPhysChem, 6(5), pp. 935–941. 2005.
  • [ Abstract ]
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  We present a detailed study of the photophysical properties of a tetraphenoxy-substituted perylene bisimide derivative. The probe molecules were immobilized in a Shpol'skii matrix of hexadecane and investigated by single-molecule spectroscopy at cryogenic temperatures. By using single-molecule spectroscopic techniques we reveal the triplet substate kinetics and the fluorescence quantum yield, and we provide an estimate for the S1–S0 transition dipole moment.

  @article{CPHC:CPHC200400555, abstract = {We present a detailed study of the photophysical properties of a tetraphenoxy-substituted perylene bisimide derivative. The probe molecules were immobilized in a Shpol'skii matrix of hexadecane and investigated by single-molecule spectroscopy at cryogenic temperatures. By using single-molecule spectroscopic techniques we reveal the triplet substate kinetics and the fluorescence quantum yield, and we provide an estimate for the S1–S0 transition dipole moment.}, author = {Lang, Erwin and Würthner, Frank and Köhler, Jürgen}, journal = {ChemPhysChem}, keywords = {myown}, number = 5, pages = {935–941}, publisher = {WILEY-VCH Verlag}, title = {Photophysical Properties of a Tetraphenoxy-Substituted Perylene Bisimide Derivative Characterized by Single-Molecule Spectroscopy}, volume = 6, year = 2005 }

  %0 Journal Article %1 CPHC:CPHC200400555 %A Lang, Erwin %A Würthner, Frank %A Köhler, Jürgen %D 2005 %I WILEY-VCH Verlag %J ChemPhysChem %N 5 %P 935--941 %R 10.1002/cphc.200400555 %T Photophysical Properties of a Tetraphenoxy-Substituted Perylene Bisimide Derivative Characterized by Single-Molecule Spectroscopy %U http://dx.doi.org/10.1002/cphc.200400555 %V 6 %X We present a detailed study of the photophysical properties of a tetraphenoxy-substituted perylene bisimide derivative. The probe molecules were immobilized in a Shpol'skii matrix of hexadecane and investigated by single-molecule spectroscopy at cryogenic temperatures. By using single-molecule spectroscopic techniques we reveal the triplet substate kinetics and the fluorescence quantum yield, and we provide an estimate for the S1–S0 transition dipole moment.
• Dramatic increase in charge carrier lifetime in a liquid crystalline perylene bisimide derivative upon bay substitution with chlorine. Debije, Michael G.; Chen, Zhijian; Piris, Jorge; Neder, Reinhard B.; Watson, Mark M.; Mullen, Klaus; Würthner, Frank. In J. Mater. Chem., 15(12), pp. 1270–1276. 2005.
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  • [ DOI ]
  A perylene bisimide derivative bearing four chlorine substituents in the bay positions exhibits charge carrier mobility in the liquid crystalline phase similar to its parent compound, but the charge carrier lifetime is over 100 times greater than found in the non-chlorinated parent compound. This dramatic increase in lifetime is explained in terms of increased order in the modified material. This enhanced lifetime persists when the material is blended with hexabenzocoronene derivatives, and suggests the chlorinated derivative may find usefulness in device architectures where extended carrier lifetime is desirable.

  @article{B416407E, abstract = {A perylene bisimide derivative bearing four chlorine substituents in the bay positions exhibits charge carrier mobility in the liquid crystalline phase similar to its parent compound{,} but the charge carrier lifetime is over 100 times greater than found in the non-chlorinated parent compound. This dramatic increase in lifetime is explained in terms of increased order in the modified material. This enhanced lifetime persists when the material is blended with hexabenzocoronene derivatives{,} and suggests the chlorinated derivative may find usefulness in device architectures where extended carrier lifetime is desirable.}, author = {Debije, Michael G. and Chen, Zhijian and Piris, Jorge and Neder, Reinhard B. and Watson, Mark M. and Mullen, Klaus and Würthner, Frank}, journal = {J. Mater. Chem.}, keywords = {myown}, number = 12, pages = {1270-1276}, publisher = {The Royal Society of Chemistry}, title = {Dramatic increase in charge carrier lifetime in a liquid crystalline perylene bisimide derivative upon bay substitution with chlorine}, volume = 15, year = 2005 }

  %0 Journal Article %1 B416407E %A Debije, Michael G. %A Chen, Zhijian %A Piris, Jorge %A Neder, Reinhard B. %A Watson, Mark M. %A Mullen, Klaus %A Würthner, Frank %D 2005 %I The Royal Society of Chemistry %J J. Mater. Chem. %N 12 %P 1270-1276 %R 10.1039/B416407E %T Dramatic increase in charge carrier lifetime in a liquid crystalline perylene bisimide derivative upon bay substitution with chlorine %U http://dx.doi.org/10.1039/B416407E %V 15 %X A perylene bisimide derivative bearing four chlorine substituents in the bay positions exhibits charge carrier mobility in the liquid crystalline phase similar to its parent compound, but the charge carrier lifetime is over 100 times greater than found in the non-chlorinated parent compound. This dramatic increase in lifetime is explained in terms of increased order in the modified material. This enhanced lifetime persists when the material is blended with hexabenzocoronene derivatives, and suggests the chlorinated derivative may find usefulness in device architectures where extended carrier lifetime is desirable.
• Metallosupramolecular approach toward functional coordination polymers. Dobrawa, Rainer; Würthner, Frank. In Journal of Polymer Science Part A: Polymer Chemistry, 43(21), pp. 4981–4995. 2005.
  • [ Abstract ]
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  An appropriate definition of metallosupramolecular coordination polymer is offered, and the relationship between the polymer length, binding constant, and concentration is clarified. The possibility of influencing the binding constant with chelating ligands is discussed on the basis of examples of different Zn2+ complexes and their respective binding constants. In the main part, coordination polymers constructed by a supramolecular approach from different metal ions and pyridine–ligand systems are highlighted, and their applications as functional materials for artificial membrane and enzyme models, responsive gels, light-harvesting systems, and organic light-emitting diodes are discussed on the basis of individual examples. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 4981–4995, 2005

  @article{POLA:POLA20997, abstract = {An appropriate definition of metallosupramolecular coordination polymer is offered, and the relationship between the polymer length, binding constant, and concentration is clarified. The possibility of influencing the binding constant with chelating ligands is discussed on the basis of examples of different Zn2+ complexes and their respective binding constants. In the main part, coordination polymers constructed by a supramolecular approach from different metal ions and pyridine–ligand systems are highlighted, and their applications as functional materials for artificial membrane and enzyme models, responsive gels, light-harvesting systems, and organic light-emitting diodes are discussed on the basis of individual examples. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 4981–4995, 2005}, author = {Dobrawa, Rainer and Würthner, Frank}, journal = {Journal of Polymer Science Part A: Polymer Chemistry}, keywords = {myown}, number = 21, pages = {4981–4995}, publisher = {Wiley Subscription Services, Inc., A Wiley Company}, title = {Metallosupramolecular approach toward functional coordination polymers}, volume = 43, year = 2005 }

  %0 Journal Article %1 POLA:POLA20997 %A Dobrawa, Rainer %A Würthner, Frank %D 2005 %I Wiley Subscription Services, Inc., A Wiley Company %J Journal of Polymer Science Part A: Polymer Chemistry %N 21 %P 4981--4995 %R 10.1002/pola.20997 %T Metallosupramolecular approach toward functional coordination polymers %U http://dx.doi.org/10.1002/pola.20997 %V 43 %X An appropriate definition of metallosupramolecular coordination polymer is offered, and the relationship between the polymer length, binding constant, and concentration is clarified. The possibility of influencing the binding constant with chelating ligands is discussed on the basis of examples of different Zn2+ complexes and their respective binding constants. In the main part, coordination polymers constructed by a supramolecular approach from different metal ions and pyridine–ligand systems are highlighted, and their applications as functional materials for artificial membrane and enzyme models, responsive gels, light-harvesting systems, and organic light-emitting diodes are discussed on the basis of individual examples. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 4981–4995, 2005
• Supramolecular Stereomutation in Kinetic and Thermodynamic Self-Assembly of Helical Merocyanine Dye Nanorods. Lohr, Andreas; Lysetska, Marina; Würthner, Frank. In Angew. Chem. Int. Ed., 44(32), pp. 5071–5074. 2005.
  • [ BibTeX ]
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  • [ DOI ]
  @article{ANIE:ANIE200500640, author = {Lohr, Andreas and Lysetska, Marina and Würthner, Frank}, journal = {Angew. Chem. Int. Ed.}, keywords = {myown}, number = 32, pages = {5071–5074}, publisher = {WILEY-VCH Verlag}, title = {Supramolecular Stereomutation in Kinetic and Thermodynamic Self-Assembly of Helical Merocyanine Dye Nanorods}, volume = 44, year = 2005 }

  %0 Journal Article %1 ANIE:ANIE200500640 %A Lohr, Andreas %A Lysetska, Marina %A Würthner, Frank %D 2005 %I WILEY-VCH Verlag %J Angew. Chem. Int. Ed. %N 32 %P 5071--5074 %R 10.1002/anie.200500640 %T Supramolecular Stereomutation in Kinetic and Thermodynamic Self-Assembly of Helical Merocyanine Dye Nanorods %U http://dx.doi.org/10.1002/anie.200500640 %V 44
• Hydrogen bond directed self-assembly of core-substituted naphthalene bisimides with melamines in solution and at the graphite interface. Thalacker, Christoph; Miura, Atsushi; De Feyter, Steven; De Schryver, Frans C.; Würthner, Frank. In Org. Biomol. Chem., 3(3), pp. 414–422. 2005.
  • [ Abstract ]
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  A series of red and blue highly fluorescent core-substituted naphthalene bisimide dyes has been synthesized and they have been investigated as supramolecular building blocks. NMR and UV-Vis titration experiments of these dyes with complementary melamines revealed the formation of triple hydrogen bonds (DAD-ADA arrays) in solution. At stoichiometric ratios, ditopic melamine receptors could dissolve otherwise insoluble bisimides by means of hydrogen bonding, even in aliphatic solvents. At the solution/graphite interface, one-dimensional chains of hydrogen bonded naphthalene bisimides and two-dimensional adlayers of ditopic melamines are formed for the pure compounds but little evidence for heterocomplexes between the two complementary building blocks could be obtained.

  @article{B414443K, abstract = {A series of red and blue highly fluorescent core-substituted naphthalene bisimide dyes has been synthesized and they have been investigated as supramolecular building blocks. NMR and UV-Vis titration experiments of these dyes with complementary melamines revealed the formation of triple hydrogen bonds (DAD-ADA arrays) in solution. At stoichiometric ratios{,} ditopic melamine receptors could dissolve otherwise insoluble bisimides by means of hydrogen bonding{,} even in aliphatic solvents. At the solution/graphite interface{,} one-dimensional chains of hydrogen bonded naphthalene bisimides and two-dimensional adlayers of ditopic melamines are formed for the pure compounds but little evidence for heterocomplexes between the two complementary building blocks could be obtained.}, author = {Thalacker, Christoph and Miura, Atsushi and De Feyter, Steven and De Schryver, Frans C. and Würthner, Frank}, journal = {Org. Biomol. Chem.}, keywords = {myown}, number = 3, pages = {414-422}, publisher = {The Royal Society of Chemistry}, title = {Hydrogen bond directed self-assembly of core-substituted naphthalene bisimides with melamines in solution and at the graphite interface}, volume = 3, year = 2005 }

  %0 Journal Article %1 B414443K %A Thalacker, Christoph %A Miura, Atsushi %A De Feyter, Steven %A De Schryver, Frans C. %A Würthner, Frank %D 2005 %I The Royal Society of Chemistry %J Org. Biomol. Chem. %N 3 %P 414-422 %R 10.1039/B414443K %T Hydrogen bond directed self-assembly of core-substituted naphthalene bisimides with melamines in solution and at the graphite interface %U http://dx.doi.org/10.1039/B414443K %V 3 %X A series of red and blue highly fluorescent core-substituted naphthalene bisimide dyes has been synthesized and they have been investigated as supramolecular building blocks. NMR and UV-Vis titration experiments of these dyes with complementary melamines revealed the formation of triple hydrogen bonds (DAD-ADA arrays) in solution. At stoichiometric ratios, ditopic melamine receptors could dissolve otherwise insoluble bisimides by means of hydrogen bonding, even in aliphatic solvents. At the solution/graphite interface, one-dimensional chains of hydrogen bonded naphthalene bisimides and two-dimensional adlayers of ditopic melamines are formed for the pure compounds but little evidence for heterocomplexes between the two complementary building blocks could be obtained.
• Ultrafast Energy-Electron Transfer Cascade in a Multichromophoric Light-Harvesting Molecular Square. Sautter, Armin; Kaletaş, Başak Kükrer; Schmid, Dietmar G.; Dobrawa, Rainer; Zimine, Mikhail; Jung, Günther; van Stokkum, Ivo H. M.; De Cola, Luisa; Williams, René M.; Würthner, Frank. In J. Am. Chem. Soc., 127(18), pp. 6719–6729. 2005.

  PMID: 15869294
  • [ Abstract ]
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  A molecular square with dimensions of about 4 nm, incorporating sixteen pyrene chromophores attached to four ditopic bay-functionalized perylene bisimide chromophores, has been synthesized by coordination to four Pt(II) phosphine corner units and fully characterized via NMR spectroscopy and ESI-FTICR mass spectrometry. Steady-state and time-resolved emission as well as femtosecond transient absorption studies reveal the presence of a highly efficient (>90\%) and fast photoinduced energy transfer (ken ≈ 5.0 × 109 s-1) from the pyrene to the perylene bisimide chromophores and a very fast and efficient electron transfer (>94\%, ket ≈ 5 × 1011 up to 43 × 1011 s-1). Spectrotemporal parametrization indicates upper excited-state electron-transfer processes, various energy and electron-transfer pathways, and chromophoric heterogeneity. Temperature-dependent time-resolved emission spectroscopy has shown that the acceptor emission lifetime increases with decreasing temperature from which an electron-transfer barrier is obtained. The extremely fast electron-transfer processes (substantially faster and more efficient than in the free ligand) that are normally only observed in solid materials, together with the closely packed structure of 20 chromophoric units, indicate that we can consider the molecular square as a monodisperse nanoaggregate:  a molecularly defined ensemble of chromophores that partly behaves like a solid material.

  @article{doi:10.1021/ja0448216, abstract = {A molecular square with dimensions of about 4 nm, incorporating sixteen pyrene chromophores attached to four ditopic bay-functionalized perylene bisimide chromophores, has been synthesized by coordination to four Pt(II) phosphine corner units and fully characterized via NMR spectroscopy and ESI-FTICR mass spectrometry. Steady-state and time-resolved emission as well as femtosecond transient absorption studies reveal the presence of a highly efficient (>90\%) and fast photoinduced energy transfer (ken ≈ 5.0 × 109 s-1) from the pyrene to the perylene bisimide chromophores and a very fast and efficient electron transfer (>94\%, ket ≈ 5 × 1011 up to 43 × 1011 s-1). Spectrotemporal parametrization indicates upper excited-state electron-transfer processes, various energy and electron-transfer pathways, and chromophoric heterogeneity. Temperature-dependent time-resolved emission spectroscopy has shown that the acceptor emission lifetime increases with decreasing temperature from which an electron-transfer barrier is obtained. The extremely fast electron-transfer processes (substantially faster and more efficient than in the free ligand) that are normally only observed in solid materials, together with the closely packed structure of 20 chromophoric units, indicate that we can consider the molecular square as a monodisperse nanoaggregate:  a molecularly defined ensemble of chromophores that partly behaves like a solid material.}, author = {Sautter, Armin and Kaletaş, Başak Kükrer and Schmid, Dietmar G. and Dobrawa, Rainer and Zimine, Mikhail and Jung, Günther and van Stokkum, Ivo H. M. and De Cola, Luisa and Williams, René M. and Würthner, Frank}, journal = {J. Am. Chem. Soc.}, keywords = {myown}, note = {PMID: 15869294}, number = 18, pages = {6719-6729}, title = {Ultrafast Energy-Electron Transfer Cascade in a Multichromophoric Light-Harvesting Molecular Square}, volume = 127, year = 2005 }

  %0 Journal Article %1 doi:10.1021/ja0448216 %A Sautter, Armin %A Kaletaş, Başak Kükrer %A Schmid, Dietmar G. %A Dobrawa, Rainer %A Zimine, Mikhail %A Jung, Günther %A van Stokkum, Ivo H. M. %A De Cola, Luisa %A Williams, René M. %A Würthner, Frank %D 2005 %J J. Am. Chem. Soc. %N 18 %P 6719-6729 %R 10.1021/ja0448216 %T Ultrafast Energy-Electron Transfer Cascade in a Multichromophoric Light-Harvesting Molecular Square %U http://dx.doi.org/10.1021/ja0448216 %V 127 %X A molecular square with dimensions of about 4 nm, incorporating sixteen pyrene chromophores attached to four ditopic bay-functionalized perylene bisimide chromophores, has been synthesized by coordination to four Pt(II) phosphine corner units and fully characterized via NMR spectroscopy and ESI-FTICR mass spectrometry. Steady-state and time-resolved emission as well as femtosecond transient absorption studies reveal the presence of a highly efficient (>90\%) and fast photoinduced energy transfer (ken ≈ 5.0 × 109 s-1) from the pyrene to the perylene bisimide chromophores and a very fast and efficient electron transfer (>94\%, ket ≈ 5 × 1011 up to 43 × 1011 s-1). Spectrotemporal parametrization indicates upper excited-state electron-transfer processes, various energy and electron-transfer pathways, and chromophoric heterogeneity. Temperature-dependent time-resolved emission spectroscopy has shown that the acceptor emission lifetime increases with decreasing temperature from which an electron-transfer barrier is obtained. The extremely fast electron-transfer processes (substantially faster and more efficient than in the free ligand) that are normally only observed in solid materials, together with the closely packed structure of 20 chromophoric units, indicate that we can consider the molecular square as a monodisperse nanoaggregate:  a molecularly defined ensemble of chromophores that partly behaves like a solid material.
• Gelation of a Highly Fluorescent Urea-Functionalized Perylene Bisimide Dye. Würthner, Frank; Hanke, Bertil; Lysetska, Marina; Lambright, Geoffrey; Harms, Gregory S. In Organic Letters, 7(6), pp. 967–970. 2005.

  PMID: 15760115
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  A urea-containing tetraphenoxy-substituted perylene bisimide has been synthesized, and its gelation ability has been studied. This functional dye forms fluorescent organogels in toluene and tetrachloromethane through self-assembly by hydrogen-bonding and π−π-stacking interactions. AFM and confocal laser scanning microscopy reveal the formation of fiberlike aggregates.

  @article{doi:10.1021/ol0475820, abstract = {A urea-containing tetraphenoxy-substituted perylene bisimide has been synthesized, and its gelation ability has been studied. This functional dye forms fluorescent organogels in toluene and tetrachloromethane through self-assembly by hydrogen-bonding and π−π-stacking interactions. AFM and confocal laser scanning microscopy reveal the formation of fiberlike aggregates.}, author = {Würthner, Frank and Hanke, Bertil and Lysetska, Marina and Lambright, Geoffrey and Harms, Gregory S.}, journal = {Organic Letters}, keywords = {myown}, note = {PMID: 15760115}, number = 6, pages = {967-970}, title = {Gelation of a Highly Fluorescent Urea-Functionalized Perylene Bisimide Dye}, volume = 7, year = 2005 }

  %0 Journal Article %1 doi:10.1021/ol0475820 %A Würthner, Frank %A Hanke, Bertil %A Lysetska, Marina %A Lambright, Geoffrey %A Harms, Gregory S. %D 2005 %J Organic Letters %N 6 %P 967-970 %R 10.1021/ol0475820 %T Gelation of a Highly Fluorescent Urea-Functionalized Perylene Bisimide Dye %U http://dx.doi.org/10.1021/ol0475820 %V 7 %X A urea-containing tetraphenoxy-substituted perylene bisimide has been synthesized, and its gelation ability has been studied. This functional dye forms fluorescent organogels in toluene and tetrachloromethane through self-assembly by hydrogen-bonding and π−π-stacking interactions. AFM and confocal laser scanning microscopy reveal the formation of fiberlike aggregates.

• Supramolecular p−n-Heterojunctions by Co-Self-Organization of Oligo(p-phenylene Vinylene) and Perylene Bisimide Dyes. Würthner, Frank; Chen, Zhijian; Hoeben, Freek J. M.; Osswald, Peter; You, Chang-Cheng; Jonkheijm, Pascal; Herrikhuyzen, Jeroen v.; Schenning, Albertus P. H. J.; van der Schoot, Paul P. A. M.; Meijer, E. W.; Beckers, Edwin H. A.; Meskers, Stefan C. J.; Janssen, René A. J. In J. Am. Chem. Soc., 126(34), pp. 10611–10618. 2004.

  PMID: 15327319
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  Comparative studies on hydrogen-bonded versus covalently linked donor−acceptor−donor dye arrays obtained from oligo(p-phenylene vinylene)s (OPVs) as donor and bay-substituted perylene bisimides (PERYs) as acceptor dyes are presented. Both systems form well-ordered J-type aggregates in methylcyclohexane, but only hydrogen-bonded arrays afford hierarchically assembled chiral OPV−PERY dye superstructures consisting of left-handed helical π−π co-aggregates (CD spectroscopy) of the two dyes that further assemble into right-handed nanometer-scale supercoils in the solid state (AFM study). In the case of hydrogen-bonded arrays, the stability of the aggregates in solution increases with increasing conjugation length of the OPV unit. The well-defined co-aggregated dyes presented here exhibit photoinduced electron transfer on subpicosecond time scale, and thus, these supramolecular entities might serve as valuable nanoscopic functional units.

  @article{doi:10.1021/ja0475353, abstract = {Comparative studies on hydrogen-bonded versus covalently linked donor−acceptor−donor dye arrays obtained from oligo(p-phenylene vinylene)s (OPVs) as donor and bay-substituted perylene bisimides (PERYs) as acceptor dyes are presented. Both systems form well-ordered J-type aggregates in methylcyclohexane, but only hydrogen-bonded arrays afford hierarchically assembled chiral OPV−PERY dye superstructures consisting of left-handed helical π−π co-aggregates (CD spectroscopy) of the two dyes that further assemble into right-handed nanometer-scale supercoils in the solid state (AFM study). In the case of hydrogen-bonded arrays, the stability of the aggregates in solution increases with increasing conjugation length of the OPV unit. The well-defined co-aggregated dyes presented here exhibit photoinduced electron transfer on subpicosecond time scale, and thus, these supramolecular entities might serve as valuable nanoscopic functional units.}, author = {Würthner, Frank and Chen, Zhijian and Hoeben, Freek J. M. and Osswald, Peter and You, Chang-Cheng and Jonkheijm, Pascal and Herrikhuyzen, Jeroen v. and Schenning, Albertus P. H. J. and van der Schoot, Paul P. A. M. and Meijer, E. W. and Beckers, Edwin H. A. and Meskers, Stefan C. J. and Janssen, René A. J.}, journal = {J. Am. Chem. Soc.}, keywords = {myown}, note = {PMID: 15327319}, number = 34, pages = {10611-10618}, title = {Supramolecular p−n-Heterojunctions by Co-Self-Organization of Oligo(p-phenylene Vinylene) and Perylene Bisimide Dyes}, volume = 126, year = 2004 }

  %0 Journal Article %1 doi:10.1021/ja0475353 %A Würthner, Frank %A Chen, Zhijian %A Hoeben, Freek J. M. %A Osswald, Peter %A You, Chang-Cheng %A Jonkheijm, Pascal %A Herrikhuyzen, Jeroen v. %A Schenning, Albertus P. H. J. %A van der Schoot, Paul P. A. M. %A Meijer, E. W. %A Beckers, Edwin H. A. %A Meskers, Stefan C. J. %A Janssen, René A. J. %D 2004 %J J. Am. Chem. Soc. %N 34 %P 10611-10618 %R 10.1021/ja0475353 %T Supramolecular p−n-Heterojunctions by Co-Self-Organization of Oligo(p-phenylene Vinylene) and Perylene Bisimide Dyes %U http://dx.doi.org/10.1021/ja0475353 %V 126 %X Comparative studies on hydrogen-bonded versus covalently linked donor−acceptor−donor dye arrays obtained from oligo(p-phenylene vinylene)s (OPVs) as donor and bay-substituted perylene bisimides (PERYs) as acceptor dyes are presented. Both systems form well-ordered J-type aggregates in methylcyclohexane, but only hydrogen-bonded arrays afford hierarchically assembled chiral OPV−PERY dye superstructures consisting of left-handed helical π−π co-aggregates (CD spectroscopy) of the two dyes that further assemble into right-handed nanometer-scale supercoils in the solid state (AFM study). In the case of hydrogen-bonded arrays, the stability of the aggregates in solution increases with increasing conjugation length of the OPV unit. The well-defined co-aggregated dyes presented here exhibit photoinduced electron transfer on subpicosecond time scale, and thus, these supramolecular entities might serve as valuable nanoscopic functional units.
• Perylene bisimide dyes as versatile building blocks for functional supramolecular architectures. Würthner, Frank. In Chem. Commun., (14), pp. 1564–1579. 2004.
  • [ Abstract ]
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  • [ DOI ]
  Perylene bisimide dyes and their organization into supramolecular architectures through hydrogen-bonding, metal ion coordination and [small pi]-[small pi]-stacking is discussed; further self-assembly leading to nano- and meso-scopic structures and liquid-crystalline compounds is also addressed.

  @article{B401630K, abstract = {Perylene bisimide dyes and their organization into supramolecular architectures through hydrogen-bonding{,} metal ion coordination and [small pi]-[small pi]-stacking is discussed; further self-assembly leading to nano- and meso-scopic structures and liquid-crystalline compounds is also addressed.}, author = {Würthner, Frank}, journal = {Chem. Commun.}, keywords = {myown}, number = 14, pages = {1564-1579}, publisher = {The Royal Society of Chemistry}, title = {Perylene bisimide dyes as versatile building blocks for functional supramolecular architectures}, year = 2004 }

  %0 Journal Article %1 B401630K %A Würthner, Frank %D 2004 %I The Royal Society of Chemistry %J Chem. Commun. %N 14 %P 1564-1579 %R 10.1039/B401630K %T Perylene bisimide dyes as versatile building blocks for functional supramolecular architectures %U http://dx.doi.org/10.1039/B401630K %X Perylene bisimide dyes and their organization into supramolecular architectures through hydrogen-bonding, metal ion coordination and [small pi]-[small pi]-stacking is discussed; further self-assembly leading to nano- and meso-scopic structures and liquid-crystalline compounds is also addressed.
• Supramolecular Polymerization and Gel Formation of Bis(Merocyanine) Dyes Driven by Dipolar Aggregation. Yao, Sheng; Beginn, Uwe; Gress, Tobias; Lysetska, Marina; Würthner, Frank. In J. Am. Chem. Soc., 126(26), pp. 8336–8348. 2004.

  PMID: 15225077
  • [ Abstract ]
  • [ BibTeX ]
  • [ EndNote ]
  • [ DOI ]
  Two highly dipolar merocyanine dyes were tethered by a rigid tris(n-dodecyloxy)xylylene unit that preorganizes the dyes for a supramolecular polymerization process through intermolecular aggregation of the dyes. UV/vis spectroscopy revealed a solvent dependent equilibrium between monomeric dyes and two different types of dye aggregates that are characterized by hypsochromically shifted D- and H-type absorption bands. Taking into account the ditopic nature of the supramolecular building blocks, the occurrence of the D-band indicates the formation of an oligomeric/polymeric supramolecular chain whereas the observation of the H-band suggests a higher order assembly. For the H-aggregated dyes, intrinsic viscosities exceed 0.65 L g-1 in methylcyclohexane, values typically found for macromolecular solutions. At higher concentration, further association of these aggregates takes place by entanglement of the alkyl groups leading to a substantial increase in viscosity and gelation. Rheology studies show linear viscoelastic behavior which was attributed to the formation of an entangled dynamic network. AFM and cryo-TEM studies of the gel reveal long and stiff rod-type assemblies. X-ray diffraction studies for a solid film show columnar mesomorphism. Based on these results, a structural model is proposed in which six helically preorganized strands of the supramolecular polymer intertwine to form a rod with a diameter of about 5 nm. Within these rods all dyes are tightly aggregated in a tubular fashion giving rise to delocalized excitonic states, and the π-conjugated tube is jacketed by the tridodecyloxy groups.

  @article{doi:10.1021/ja0496367, abstract = {Two highly dipolar merocyanine dyes were tethered by a rigid tris(n-dodecyloxy)xylylene unit that preorganizes the dyes for a supramolecular polymerization process through intermolecular aggregation of the dyes. UV/vis spectroscopy revealed a solvent dependent equilibrium between monomeric dyes and two different types of dye aggregates that are characterized by hypsochromically shifted D- and H-type absorption bands. Taking into account the ditopic nature of the supramolecular building blocks, the occurrence of the D-band indicates the formation of an oligomeric/polymeric supramolecular chain whereas the observation of the H-band suggests a higher order assembly. For the H-aggregated dyes, intrinsic viscosities exceed 0.65 L g-1 in methylcyclohexane, values typically found for macromolecular solutions. At higher concentration, further association of these aggregates takes place by entanglement of the alkyl groups leading to a substantial increase in viscosity and gelation. Rheology studies show linear viscoelastic behavior which was attributed to the formation of an entangled dynamic network. AFM and cryo-TEM studies of the gel reveal long and stiff rod-type assemblies. X-ray diffraction studies for a solid film show columnar mesomorphism. Based on these results, a structural model is proposed in which six helically preorganized strands of the supramolecular polymer intertwine to form a rod with a diameter of about 5 nm. Within these rods all dyes are tightly aggregated in a tubular fashion giving rise to delocalized excitonic states, and the π-conjugated tube is jacketed by the tridodecyloxy groups.}, author = {Yao, Sheng and Beginn, Uwe and Gress, Tobias and Lysetska, Marina and Würthner, Frank}, journal = {J. Am. Chem. Soc.}, keywords = {myown}, note = {PMID: 15225077}, number = 26, pages = {8336-8348}, title = {Supramolecular Polymerization and Gel Formation of Bis(Merocyanine) Dyes Driven by Dipolar Aggregation}, volume = 126, year = 2004 }

  %0 Journal Article %1 doi:10.1021/ja0496367 %A Yao, Sheng %A Beginn, Uwe %A Gress, Tobias %A Lysetska, Marina %A Würthner, Frank %D 2004 %J J. Am. Chem. Soc. %N 26 %P 8336-8348 %R 10.1021/ja0496367 %T Supramolecular Polymerization and Gel Formation of Bis(Merocyanine) Dyes Driven by Dipolar Aggregation %U http://dx.doi.org/10.1021/ja0496367 %V 126 %X Two highly dipolar merocyanine dyes were tethered by a rigid tris(n-dodecyloxy)xylylene unit that preorganizes the dyes for a supramolecular polymerization process through intermolecular aggregation of the dyes. UV/vis spectroscopy revealed a solvent dependent equilibrium between monomeric dyes and two different types of dye aggregates that are characterized by hypsochromically shifted D- and H-type absorption bands. Taking into account the ditopic nature of the supramolecular building blocks, the occurrence of the D-band indicates the formation of an oligomeric/polymeric supramolecular chain whereas the observation of the H-band suggests a higher order assembly. For the H-aggregated dyes, intrinsic viscosities exceed 0.65 L g-1 in methylcyclohexane, values typically found for macromolecular solutions. At higher concentration, further association of these aggregates takes place by entanglement of the alkyl groups leading to a substantial increase in viscosity and gelation. Rheology studies show linear viscoelastic behavior which was attributed to the formation of an entangled dynamic network. AFM and cryo-TEM studies of the gel reveal long and stiff rod-type assemblies. X-ray diffraction studies for a solid film show columnar mesomorphism. Based on these results, a structural model is proposed in which six helically preorganized strands of the supramolecular polymer intertwine to form a rod with a diameter of about 5 nm. Within these rods all dyes are tightly aggregated in a tubular fashion giving rise to delocalized excitonic states, and the π-conjugated tube is jacketed by the tridodecyloxy groups.
• Synthesis and electropolymerization of novel oligothiophene-functionalized perylene bisimides. You, Chang-Cheng; Saha-Moller, Chantu R.; Würthner, Frank. In Chem. Commun., (18), pp. 2030–2031. 2004.
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  Fourfold oligothiophene-functionalized perylene bisimides have been synthesized by esterification of hydroxyphenoxy-substituted perylene bisimides and their optical properties as well as electrochemical polymerization properties have been investigated.

  @article{B407551J, abstract = {Fourfold oligothiophene-functionalized perylene bisimides have been synthesized by esterification of hydroxyphenoxy-substituted perylene bisimides and their optical properties as well as electrochemical polymerization properties have been investigated.}, author = {You, Chang-Cheng and Saha-Moller, Chantu R. and Würthner, Frank}, journal = {Chem. Commun.}, keywords = {myown}, number = 18, pages = {2030-2031}, publisher = {The Royal Society of Chemistry}, title = {Synthesis and electropolymerization of novel oligothiophene-functionalized perylene bisimides}, year = 2004 }

  %0 Journal Article %1 B407551J %A You, Chang-Cheng %A Saha-Moller, Chantu R. %A Würthner, Frank %D 2004 %I The Royal Society of Chemistry %J Chem. Commun. %N 18 %P 2030-2031 %R 10.1039/B407551J %T Synthesis and electropolymerization of novel oligothiophene-functionalized perylene bisimides %U http://dx.doi.org/10.1039/B407551J %X Fourfold oligothiophene-functionalized perylene bisimides have been synthesized by esterification of hydroxyphenoxy-substituted perylene bisimides and their optical properties as well as electrochemical polymerization properties have been investigated.
• Metallosupramolecular squares: from structure to function. Würthner, Frank; You, Chang-Cheng; Saha-Moller, Chantu R. In Chem. Soc. Rev., 33(3), pp. 133–146. 2004.
  • [ Abstract ]
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  Metallosupramolecular squares have been successfully evolved over the past years as versatile substitutes of the conventional organic macrocycles owing to the development of reliable synthetic protocols and abundant structural variability (metals and ligands). In this review we have presented the fundamental aspects of metallosupramolecular squares such as the strategies for their construction (self-assembly vs. kinetically controlled macrocyclization) and characterization. The major emphasis of this tutorial review lies on the function of metallosupramolecular squares. Thus, the introduction of functionality into these systems has been discussed in detail by highlighting the recent progress toward application in various fields, including molecular recognition, enantioselective sensing, photoluminescence, redox activity and electrochemical sensing, and homogeneous catalysis.

  @article{B300512G, abstract = {Metallosupramolecular squares have been successfully evolved over the past years as versatile substitutes of the conventional organic macrocycles owing to the development of reliable synthetic protocols and abundant structural variability (metals and ligands). In this review we have presented the fundamental aspects of metallosupramolecular squares such as the strategies for their construction (self-assembly vs. kinetically controlled macrocyclization) and characterization. The major emphasis of this tutorial review lies on the function of metallosupramolecular squares. Thus{,} the introduction of functionality into these systems has been discussed in detail by highlighting the recent progress toward application in various fields{,} including molecular recognition{,} enantioselective sensing{,} photoluminescence{,} redox activity and electrochemical sensing{,} and homogeneous catalysis.}, author = {Würthner, Frank and You, Chang-Cheng and Saha-Moller, Chantu R.}, journal = {Chem. Soc. Rev.}, keywords = {myown}, number = 3, pages = {133-146}, publisher = {The Royal Society of Chemistry}, title = {Metallosupramolecular squares: from structure to function}, volume = 33, year = 2004 }

  %0 Journal Article %1 B300512G %A Würthner, Frank %A You, Chang-Cheng %A Saha-Moller, Chantu R. %D 2004 %I The Royal Society of Chemistry %J Chem. Soc. Rev. %N 3 %P 133-146 %R 10.1039/B300512G %T Metallosupramolecular squares: from structure to function %U http://dx.doi.org/10.1039/B300512G %V 33 %X Metallosupramolecular squares have been successfully evolved over the past years as versatile substitutes of the conventional organic macrocycles owing to the development of reliable synthetic protocols and abundant structural variability (metals and ligands). In this review we have presented the fundamental aspects of metallosupramolecular squares such as the strategies for their construction (self-assembly vs. kinetically controlled macrocyclization) and characterization. The major emphasis of this tutorial review lies on the function of metallosupramolecular squares. Thus, the introduction of functionality into these systems has been discussed in detail by highlighting the recent progress toward application in various fields, including molecular recognition, enantioselective sensing, photoluminescence, redox activity and electrochemical sensing, and homogeneous catalysis.
• Porphyrin−Perylene Bisimide Dyads and Triads:  Synthesis and Optical and Coordination Properties. You, Chang-Cheng; Würthner, Frank. In Organic Letters, 6(14), pp. 2401–2404. 2004.

  PMID: 15228289
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  Novel porphyrin perylene dyad and triad dyes have been prepared by the coupling of aminophenyltrisphenylporphyrin and tetraphenoxy-substituted perylenetetracarboxylic acid bisanhydrides in a one-step synthesis. Fluorescence spectra of these compounds reveal features that are attributable to emission of perylene bisimides as well as porphyrin excited states. The self-assembly behavior of zinc-metalated compounds with 4,4‘-bipyridine and diazabenzoperylene has been investigated by 1H NMR spectroscopy in CDCl3, showing that oligomeric zigzag assemblies are formed.

  @article{doi:10.1021/ol049206l, abstract = {Novel porphyrin perylene dyad and triad dyes have been prepared by the coupling of aminophenyltrisphenylporphyrin and tetraphenoxy-substituted perylenetetracarboxylic acid bisanhydrides in a one-step synthesis. Fluorescence spectra of these compounds reveal features that are attributable to emission of perylene bisimides as well as porphyrin excited states. The self-assembly behavior of zinc-metalated compounds with 4,4‘-bipyridine and diazabenzoperylene has been investigated by 1H NMR spectroscopy in CDCl3, showing that oligomeric zigzag assemblies are formed.}, author = {You, Chang-Cheng and Würthner, Frank}, journal = {Organic Letters}, keywords = {myown}, note = {PMID: 15228289}, number = 14, pages = {2401-2404}, title = {Porphyrin−Perylene Bisimide Dyads and Triads:  Synthesis and Optical and Coordination Properties}, volume = 6, year = 2004 }

  %0 Journal Article %1 doi:10.1021/ol049206l %A You, Chang-Cheng %A Würthner, Frank %D 2004 %J Organic Letters %N 14 %P 2401-2404 %R 10.1021/ol049206l %T Porphyrin−Perylene Bisimide Dyads and Triads:  Synthesis and Optical and Coordination Properties %U http://dx.doi.org/10.1021/ol049206l %V 6 %X Novel porphyrin perylene dyad and triad dyes have been prepared by the coupling of aminophenyltrisphenylporphyrin and tetraphenoxy-substituted perylenetetracarboxylic acid bisanhydrides in a one-step synthesis. Fluorescence spectra of these compounds reveal features that are attributable to emission of perylene bisimides as well as porphyrin excited states. The self-assembly behavior of zinc-metalated compounds with 4,4‘-bipyridine and diazabenzoperylene has been investigated by 1H NMR spectroscopy in CDCl3, showing that oligomeric zigzag assemblies are formed.
• Towards supramolecular electronics. Schenning, A.P.H.J.; Jonkheijm, P.; Hoeben, F.J.M.; van Herrikhuyzen, J.; Meskers, S.C.J.; Meijer, E.W.; Herz, L.M.; Daniel, C.; Silva, C.; Phillips, R.T.; Friend, R.H.; Beljonne, D.; Miura, A.; Feyter, S. De; Zdanowska, M.; Uji i, H.; Schryver, F.C. De; Chen, Z.; Würthner, Frank; Mas-Torrent, M.; den Boer, D.; Durkut, M.; Hadley, P. In Synthetic Metals, 147(1), pp. 43–48. 2004.

  Supramolecular approaches to organic electronics and nanotechnology. Proceedings of Symposium F. E-MRS Spring Meeting.
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  Abstract We have demonstrated that it is possible to program π-conjugated molecules to self-assemble into cylindrical aggregates in solution. By incorporating energy or electron traps in our stacks, energy and electron transfer processes in these one-dimensional assemblies have been studied in solution. The transfer of the single OPV cylinders from solution to a solid support as isolated objects was only possible when specific concentrations and specific solid supports were used. So far, however, we have not been able to measure any current through our fibers.

  @article{SCHENNING200443, abstract = {Abstract We have demonstrated that it is possible to program π-conjugated molecules to self-assemble into cylindrical aggregates in solution. By incorporating energy or electron traps in our stacks, energy and electron transfer processes in these one-dimensional assemblies have been studied in solution. The transfer of the single OPV cylinders from solution to a solid support as isolated objects was only possible when specific concentrations and specific solid supports were used. So far, however, we have not been able to measure any current through our fibers.}, author = {Schenning, A.P.H.J. and Jonkheijm, P. and Hoeben, F.J.M. and van Herrikhuyzen, J. and Meskers, S.C.J. and Meijer, E.W. and Herz, L.M. and Daniel, C. and Silva, C. and Phillips, R.T. and Friend, R.H. and Beljonne, D. and Miura, A. and Feyter, S. De and Zdanowska, M. and Uji i, H. and Schryver, F.C. De and Chen, Z. and Würthner, Frank and Mas-Torrent, M. and den Boer, D. and Durkut, M. and Hadley, P.}, journal = {Synthetic Metals}, keywords = {Oligo(phenylenevinylene)s}, note = {Supramolecular approaches to organic electronics and nanotechnology. Proceedings of Symposium F. E-MRS Spring Meeting.}, number = 1, pages = {43 - 48}, title = {Towards supramolecular electronics}, volume = 147, year = 2004 }

  %0 Journal Article %1 SCHENNING200443 %A Schenning, A.P.H.J. %A Jonkheijm, P. %A Hoeben, F.J.M. %A van Herrikhuyzen, J. %A Meskers, S.C.J. %A Meijer, E.W. %A Herz, L.M. %A Daniel, C. %A Silva, C. %A Phillips, R.T. %A Friend, R.H. %A Beljonne, D. %A Miura, A. %A Feyter, S. De %A Zdanowska, M. %A Uji i, H. %A Schryver, F.C. De %A Chen, Z. %A Würthner, Frank %A Mas-Torrent, M. %A den Boer, D. %A Durkut, M. %A Hadley, P. %D 2004 %J Synthetic Metals %N 1 %P 43 - 48 %R https://doi.org/10.1016/j.synthmet.2004.06.038 %T Towards supramolecular electronics %U http://www.sciencedirect.com/science/article/pii/S037967790400414X %V 147 %X Abstract We have demonstrated that it is possible to program π-conjugated molecules to self-assemble into cylindrical aggregates in solution. By incorporating energy or electron traps in our stacks, energy and electron transfer processes in these one-dimensional assemblies have been studied in solution. The transfer of the single OPV cylinders from solution to a solid support as isolated objects was only possible when specific concentrations and specific solid supports were used. So far, however, we have not been able to measure any current through our fibers.
• Tetrachloro-substituted Perylene Bisimide Dyes as Promising n-Type Organic Semiconductors: Studies on Structural, Electrochemical and Charge Transport Properties. Chen, Zhijian; Debije, Michael G.; Debaerdemaeker, Tony; Osswald, Peter; Würthner, Frank. In ChemPhysChem, 5(1), pp. 137–140. 2004.
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  @article{CPHC:CPHC200300882, author = {Chen, Zhijian and Debije, Michael G. and Debaerdemaeker, Tony and Osswald, Peter and Würthner, Frank}, journal = {ChemPhysChem}, keywords = {myown}, number = 1, pages = {137–140}, publisher = {WILEY-VCH Verlag}, title = {Tetrachloro-substituted Perylene Bisimide Dyes as Promising n-Type Organic Semiconductors: Studies on Structural, Electrochemical and Charge Transport Properties}, volume = 5, year = 2004 }

  %0 Journal Article %1 CPHC:CPHC200300882 %A Chen, Zhijian %A Debije, Michael G. %A Debaerdemaeker, Tony %A Osswald, Peter %A Würthner, Frank %D 2004 %I WILEY-VCH Verlag %J ChemPhysChem %N 1 %P 137--140 %R 10.1002/cphc.200300882 %T Tetrachloro-substituted Perylene Bisimide Dyes as Promising n-Type Organic Semiconductors: Studies on Structural, Electrochemical and Charge Transport Properties %U http://dx.doi.org/10.1002/cphc.200300882 %V 5
• Photoinduced Electron and Energy Transfer Processes in a Bichromophoric Pyrene−Perylene Bisimide System. Kaletaş, Başak Kükrer; Dobrawa, Rainer; Sautter, Armin; Würthner, Frank; Zimine, Mikhail; De Cola, Luisa; Williams, René M. In The Journal of Physical Chemistry A, 108(11), pp. 1900–1909. 2004.
  • [ Abstract ]
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  The synthesis and photophysical properties of a system consisting of a bay-functionalized perylene bisimide, containing four appended pyrene and two coordinating pyridine units, and its reference system are described. A complete study of their photophysical properties was obtained using UV−vis absorption, steady state and time-resolved emission, and femtosecond transient absorption. Analysis of the data, obtained from time-resolved emission and femtosecond transient absorption spectroscopy, showed the presence of both photoinduced electron and energy transfer processes. A high yield (>90\%) and fast photoinduced energy transfer (ken ≈ 6.2 × 109 s-1) is followed by efficient electron transfer (70\%, ket ≈ 6.6 × 109 s-1) from the pyrene units to the perylene bisimide moiety. The energy donor−acceptor distance, R = 8.6 Å, is calculated from the experimental energy transfer rate using Förster theory. Temperature-dependent time-resolved emission spectroscopy showed an increase of the acceptor emission lifetime with decreasing temperature. It also indicates the presence of different conformations because two different electron transfer barriers (0.08 and 0.42 eV) were found. These barrier values were corroborated by a theoretical analysis of the energetics of the process using Marcus theory, indicating average donor−acceptor distances of 4.5 Å (room temperature) to 11 Å (at low T).

  @article{doi:10.1021/jp0372688, abstract = {The synthesis and photophysical properties of a system consisting of a bay-functionalized perylene bisimide, containing four appended pyrene and two coordinating pyridine units, and its reference system are described. A complete study of their photophysical properties was obtained using UV−vis absorption, steady state and time-resolved emission, and femtosecond transient absorption. Analysis of the data, obtained from time-resolved emission and femtosecond transient absorption spectroscopy, showed the presence of both photoinduced electron and energy transfer processes. A high yield (>90\%) and fast photoinduced energy transfer (ken ≈ 6.2 × 109 s-1) is followed by efficient electron transfer (70\%, ket ≈ 6.6 × 109 s-1) from the pyrene units to the perylene bisimide moiety. The energy donor−acceptor distance, R = 8.6 Å, is calculated from the experimental energy transfer rate using Förster theory. Temperature-dependent time-resolved emission spectroscopy showed an increase of the acceptor emission lifetime with decreasing temperature. It also indicates the presence of different conformations because two different electron transfer barriers (0.08 and 0.42 eV) were found. These barrier values were corroborated by a theoretical analysis of the energetics of the process using Marcus theory, indicating average donor−acceptor distances of 4.5 Å (room temperature) to 11 Å (at low T).}, author = {Kaletaş, Başak Kükrer and Dobrawa, Rainer and Sautter, Armin and Würthner, Frank and Zimine, Mikhail and De Cola, Luisa and Williams, René M.}, journal = {The Journal of Physical Chemistry A}, keywords = {myown}, number = 11, pages = {1900-1909}, title = {Photoinduced Electron and Energy Transfer Processes in a Bichromophoric Pyrene−Perylene Bisimide System}, volume = 108, year = 2004 }

  %0 Journal Article %1 doi:10.1021/jp0372688 %A Kaletaş, Başak Kükrer %A Dobrawa, Rainer %A Sautter, Armin %A Würthner, Frank %A Zimine, Mikhail %A De Cola, Luisa %A Williams, René M. %D 2004 %J The Journal of Physical Chemistry A %N 11 %P 1900-1909 %R 10.1021/jp0372688 %T Photoinduced Electron and Energy Transfer Processes in a Bichromophoric Pyrene−Perylene Bisimide System %U http://dx.doi.org/10.1021/jp0372688 %V 108 %X The synthesis and photophysical properties of a system consisting of a bay-functionalized perylene bisimide, containing four appended pyrene and two coordinating pyridine units, and its reference system are described. A complete study of their photophysical properties was obtained using UV−vis absorption, steady state and time-resolved emission, and femtosecond transient absorption. Analysis of the data, obtained from time-resolved emission and femtosecond transient absorption spectroscopy, showed the presence of both photoinduced electron and energy transfer processes. A high yield (>90\%) and fast photoinduced energy transfer (ken ≈ 6.2 × 109 s-1) is followed by efficient electron transfer (70\%, ket ≈ 6.6 × 109 s-1) from the pyrene units to the perylene bisimide moiety. The energy donor−acceptor distance, R = 8.6 Å, is calculated from the experimental energy transfer rate using Förster theory. Temperature-dependent time-resolved emission spectroscopy showed an increase of the acceptor emission lifetime with decreasing temperature. It also indicates the presence of different conformations because two different electron transfer barriers (0.08 and 0.42 eV) were found. These barrier values were corroborated by a theoretical analysis of the energetics of the process using Marcus theory, indicating average donor−acceptor distances of 4.5 Å (room temperature) to 11 Å (at low T).
• Resonance Raman Intensity Analysis of Merocyanine Dimers in Solution. Leng, Weinan; Würthner, Frank; Kelley, Anne Myers. In The Journal of Physical Chemistry B, 108(29), pp. 10284–10294. 2004.
  • [ Abstract ]
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  Resonance Raman excitation profiles and absolute cross sections are presented for three closely related merocyanine dyes as monomers in dichloromethane solution and as H-dimers in dioxane solution. For both monomers and dimers the absorption spectra and the resonance Raman intensities of the 24 to 30 strongest vibrations are quantitatively simulated using time-dependent wave packet propagation methods to determine the geometry changes along each Franck−Condon active mode upon electronic excitation, as well as the homogeneous and inhomogeneous electronic line widths. In addition, an approach previously formulated to describe the vibronic structure of an excitonically coupled homodimer with multiple vibrational modes [Kelley, A. M. J. Chem. Phys. 2003, 119, 3320−3331] is applied to model the dimer spectra. Comparison of these two calculations demonstrates that when the intermonomer coupling is strong the theoretical absorption and resonance Raman spectra of the dimer can be very well approximated by treating the system as a “supermolecule” having a single electronic transition with appropriately rescaled vibrational displacements, transition dipole, and electronic zero−zero frequency. The experimental dimer spectra exhibit the reduced Franck−Condon activity expected from distributing the electronic excitation over two monomers. However, deviations in the intensity patterns for individual vibrations suggest additional, more specific effects of dimerization, and the electronic transition moment for the lowest allowed transition of the monomer is not conserved upon dimer formation. An excitonically coupled monomer model therefore appears inadequate to describe the electronic excitations in these strongly coupled noncovalent dimers.

  @article{doi:10.1021/jp037371x, abstract = {Resonance Raman excitation profiles and absolute cross sections are presented for three closely related merocyanine dyes as monomers in dichloromethane solution and as H-dimers in dioxane solution. For both monomers and dimers the absorption spectra and the resonance Raman intensities of the 24 to 30 strongest vibrations are quantitatively simulated using time-dependent wave packet propagation methods to determine the geometry changes along each Franck−Condon active mode upon electronic excitation, as well as the homogeneous and inhomogeneous electronic line widths. In addition, an approach previously formulated to describe the vibronic structure of an excitonically coupled homodimer with multiple vibrational modes [Kelley, A. M. J. Chem. Phys. 2003, 119, 3320−3331] is applied to model the dimer spectra. Comparison of these two calculations demonstrates that when the intermonomer coupling is strong the theoretical absorption and resonance Raman spectra of the dimer can be very well approximated by treating the system as a “supermolecule” having a single electronic transition with appropriately rescaled vibrational displacements, transition dipole, and electronic zero−zero frequency. The experimental dimer spectra exhibit the reduced Franck−Condon activity expected from distributing the electronic excitation over two monomers. However, deviations in the intensity patterns for individual vibrations suggest additional, more specific effects of dimerization, and the electronic transition moment for the lowest allowed transition of the monomer is not conserved upon dimer formation. An excitonically coupled monomer model therefore appears inadequate to describe the electronic excitations in these strongly coupled noncovalent dimers.}, author = {Leng, Weinan and Würthner, Frank and Kelley, Anne Myers}, journal = {The Journal of Physical Chemistry B}, keywords = {myown}, number = 29, pages = {10284-10294}, title = {Resonance Raman Intensity Analysis of Merocyanine Dimers in Solution}, volume = 108, year = 2004 }

  %0 Journal Article %1 doi:10.1021/jp037371x %A Leng, Weinan %A Würthner, Frank %A Kelley, Anne Myers %D 2004 %J The Journal of Physical Chemistry B %N 29 %P 10284-10294 %R 10.1021/jp037371x %T Resonance Raman Intensity Analysis of Merocyanine Dimers in Solution %U http://dx.doi.org/10.1021/jp037371x %V 108 %X Resonance Raman excitation profiles and absolute cross sections are presented for three closely related merocyanine dyes as monomers in dichloromethane solution and as H-dimers in dioxane solution. For both monomers and dimers the absorption spectra and the resonance Raman intensities of the 24 to 30 strongest vibrations are quantitatively simulated using time-dependent wave packet propagation methods to determine the geometry changes along each Franck−Condon active mode upon electronic excitation, as well as the homogeneous and inhomogeneous electronic line widths. In addition, an approach previously formulated to describe the vibronic structure of an excitonically coupled homodimer with multiple vibrational modes [Kelley, A. M. J. Chem. Phys. 2003, 119, 3320−3331] is applied to model the dimer spectra. Comparison of these two calculations demonstrates that when the intermonomer coupling is strong the theoretical absorption and resonance Raman spectra of the dimer can be very well approximated by treating the system as a “supermolecule” having a single electronic transition with appropriately rescaled vibrational displacements, transition dipole, and electronic zero−zero frequency. The experimental dimer spectra exhibit the reduced Franck−Condon activity expected from distributing the electronic excitation over two monomers. However, deviations in the intensity patterns for individual vibrations suggest additional, more specific effects of dimerization, and the electronic transition moment for the lowest allowed transition of the monomer is not conserved upon dimer formation. An excitonically coupled monomer model therefore appears inadequate to describe the electronic excitations in these strongly coupled noncovalent dimers.
• Electrostatic Self-assembly of Fluorescent Perylene Bisimide Coordination Polymers. Dobrawa, R.; Kurth, D. G.; Würthner, Frank. In Polymer Reprints, pp. 378–379. 2004.
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  @article{dobrawa2004electrostatic, author = {Dobrawa, R. and Kurth, D. G. and Würthner, Frank}, journal = {Polymer Reprints}, keywords = {myown}, pages = {378–379}, title = {Electrostatic Self-assembly of Fluorescent Perylene Bisimide Coordination Polymers.}, year = 2004 }

  %0 Journal Article %1 dobrawa2004electrostatic %A Dobrawa, R. %A Kurth, D. G. %A Würthner, Frank %D 2004 %J Polymer Reprints %P 378–379 %T Electrostatic Self-assembly of Fluorescent Perylene Bisimide Coordination Polymers.
• Charge Separation and Recombination in Photoexcited Oligo(p-phenylene vinylene):  Perylene Bisimide Arrays Close to the Marcus Inverted Region. Beckers, Edwin H. A.; Meskers, Stefan C. J.; Schenning, Albertus P. H. J.; Chen, Zhijian; Würthner, Frank; Janssen, René A. J. In The Journal of Physical Chemistry A, 108(34), pp. 6933–6937. 2004.
  • [ Abstract ]
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  The kinetics of photoinduced intramolecular charge separation and subsequent charge recombination of three oligo(p-phenylene vinylene)-perylene bisimide-oligo(p-phenylene vinylene) arrays has been studied using femtosecond pump−probe spectroscopy in solvents of different polarity. The reduction potentials of three donor−acceptor−donor molecules differ strongly as a consequence of the four substituents (R = 4-tert-butylphenoxy, H, or Cl) at the bay position of the central perylene bisimide unit. The experiments indicate that charge separation in these molecules occurs from the first excited singlet state of the perylene bisimide moiety to the charge-separated state (CSS) and to the lowest electronically excited state level of the charge-separated state (CSS*). For R = H and Cl, the rates for charge separation and charge recombination decrease with increasing change in the Gibbs free energy, and hence the molecules represent an exceptional example of molecules in which both charge separation and recombination occur close to or in the Marcus inverted region.

  @article{doi:10.1021/jp048980n, abstract = {The kinetics of photoinduced intramolecular charge separation and subsequent charge recombination of three oligo(p-phenylene vinylene)-perylene bisimide-oligo(p-phenylene vinylene) arrays has been studied using femtosecond pump−probe spectroscopy in solvents of different polarity. The reduction potentials of three donor−acceptor−donor molecules differ strongly as a consequence of the four substituents (R = 4-tert-butylphenoxy, H, or Cl) at the bay position of the central perylene bisimide unit. The experiments indicate that charge separation in these molecules occurs from the first excited singlet state of the perylene bisimide moiety to the charge-separated state (CSS) and to the lowest electronically excited state level of the charge-separated state (CSS*). For R = H and Cl, the rates for charge separation and charge recombination decrease with increasing change in the Gibbs free energy, and hence the molecules represent an exceptional example of molecules in which both charge separation and recombination occur close to or in the Marcus inverted region.}, author = {Beckers, Edwin H. A. and Meskers, Stefan C. J. and Schenning, Albertus P. H. J. and Chen, Zhijian and Würthner, Frank and Janssen, René A. J.}, journal = {The Journal of Physical Chemistry A}, keywords = {myown}, number = 34, pages = {6933-6937}, title = {Charge Separation and Recombination in Photoexcited Oligo(p-phenylene vinylene):  Perylene Bisimide Arrays Close to the Marcus Inverted Region}, volume = 108, year = 2004 }

  %0 Journal Article %1 doi:10.1021/jp048980n %A Beckers, Edwin H. A. %A Meskers, Stefan C. J. %A Schenning, Albertus P. H. J. %A Chen, Zhijian %A Würthner, Frank %A Janssen, René A. J. %D 2004 %J The Journal of Physical Chemistry A %N 34 %P 6933-6937 %R 10.1021/jp048980n %T Charge Separation and Recombination in Photoexcited Oligo(p-phenylene vinylene):  Perylene Bisimide Arrays Close to the Marcus Inverted Region %U http://dx.doi.org/10.1021/jp048980n %V 108 %X The kinetics of photoinduced intramolecular charge separation and subsequent charge recombination of three oligo(p-phenylene vinylene)-perylene bisimide-oligo(p-phenylene vinylene) arrays has been studied using femtosecond pump−probe spectroscopy in solvents of different polarity. The reduction potentials of three donor−acceptor−donor molecules differ strongly as a consequence of the four substituents (R = 4-tert-butylphenoxy, H, or Cl) at the bay position of the central perylene bisimide unit. The experiments indicate that charge separation in these molecules occurs from the first excited singlet state of the perylene bisimide moiety to the charge-separated state (CSS) and to the lowest electronically excited state level of the charge-separated state (CSS*). For R = H and Cl, the rates for charge separation and charge recombination decrease with increasing change in the Gibbs free energy, and hence the molecules represent an exceptional example of molecules in which both charge separation and recombination occur close to or in the Marcus inverted region.
• Preparation and Characterization of Regioisomerically Pure 1,7-Disubstituted Perylene Bisimide Dyes. Würthner, Frank; Stepanenko, Vladimir; Chen, Zhijian; Saha-Möller, Chantu R.; Kocher, Nikolaus; Stalke, Dietmar. In The Journal of Organic Chemistry, 69(23), pp. 7933–7939. 2004.

  PMID: 15527273
  • [ Abstract ]
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  A detailed study on bromination and subsequent imidization of perylene bisanhydride with cyclohexylamine is reported. The present results reveal that previously reported 1,7-difunctionalized perylene bisimides are presumably contaminated with the respective 1,6 regioisomers. N,N‘-Dicyclohexyl-1,7-dibromoperylene bisimide 1,7-3 is obtained for the first time in isomerically pure form, and its structure is unequivocally confirmed by X-ray analysis. By using regioisomerically pure 1,7-dibromoperylene bisimide 1,7-3, 1,7-dipyrrolidinylperylene bisimides 4a−c and 1,7-dipyrrolidinylperylene bisanhydride 5 as well as the unsymmetrically difunctionalized 1-bromo-7-pyrrolidinyl- and 1-cyano-7-pyrrolidinylperylene bisimides 7 and 8 are synthesized in good yield.

  @article{doi:10.1021/jo048880d, abstract = {A detailed study on bromination and subsequent imidization of perylene bisanhydride with cyclohexylamine is reported. The present results reveal that previously reported 1,7-difunctionalized perylene bisimides are presumably contaminated with the respective 1,6 regioisomers. N,N‘-Dicyclohexyl-1,7-dibromoperylene bisimide 1,7-3 is obtained for the first time in isomerically pure form, and its structure is unequivocally confirmed by X-ray analysis. By using regioisomerically pure 1,7-dibromoperylene bisimide 1,7-3, 1,7-dipyrrolidinylperylene bisimides 4a−c and 1,7-dipyrrolidinylperylene bisanhydride 5 as well as the unsymmetrically difunctionalized 1-bromo-7-pyrrolidinyl- and 1-cyano-7-pyrrolidinylperylene bisimides 7 and 8 are synthesized in good yield.}, author = {Würthner, Frank and Stepanenko, Vladimir and Chen, Zhijian and Saha-Möller, Chantu R. and Kocher, Nikolaus and Stalke, Dietmar}, journal = {The Journal of Organic Chemistry}, keywords = {myown}, note = {PMID: 15527273}, number = 23, pages = {7933-7939}, title = {Preparation and Characterization of Regioisomerically Pure 1,7-Disubstituted Perylene Bisimide Dyes}, volume = 69, year = 2004 }

  %0 Journal Article %1 doi:10.1021/jo048880d %A Würthner, Frank %A Stepanenko, Vladimir %A Chen, Zhijian %A Saha-Möller, Chantu R. %A Kocher, Nikolaus %A Stalke, Dietmar %D 2004 %J The Journal of Organic Chemistry %N 23 %P 7933-7939 %R 10.1021/jo048880d %T Preparation and Characterization of Regioisomerically Pure 1,7-Disubstituted Perylene Bisimide Dyes %U http://dx.doi.org/10.1021/jo048880d %V 69 %X A detailed study on bromination and subsequent imidization of perylene bisanhydride with cyclohexylamine is reported. The present results reveal that previously reported 1,7-difunctionalized perylene bisimides are presumably contaminated with the respective 1,6 regioisomers. N,N‘-Dicyclohexyl-1,7-dibromoperylene bisimide 1,7-3 is obtained for the first time in isomerically pure form, and its structure is unequivocally confirmed by X-ray analysis. By using regioisomerically pure 1,7-dibromoperylene bisimide 1,7-3, 1,7-dipyrrolidinylperylene bisimides 4a−c and 1,7-dipyrrolidinylperylene bisanhydride 5 as well as the unsymmetrically difunctionalized 1-bromo-7-pyrrolidinyl- and 1-cyano-7-pyrrolidinylperylene bisimides 7 and 8 are synthesized in good yield.
• Photoinduced Electron and Energy Transfer Processes in a Bichromophoric Pyrene−Perylene Bisimide System. Kaletaş, Başak Kükrer; Dobrawa, Rainer; Sautter, Armin; Würthner, Frank; Zimine, Mikhail; De Cola, Luisa; Williams, René M. In The Journal of Physical Chemistry A, 108(11), pp. 1900–1909. 2004.
  • [ Abstract ]
  • [ BibTeX ]
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  • [ DOI ]
  The synthesis and photophysical properties of a system consisting of a bay-functionalized perylene bisimide, containing four appended pyrene and two coordinating pyridine units, and its reference system are described. A complete study of their photophysical properties was obtained using UV−vis absorption, steady state and time-resolved emission, and femtosecond transient absorption. Analysis of the data, obtained from time-resolved emission and femtosecond transient absorption spectroscopy, showed the presence of both photoinduced electron and energy transfer processes. A high yield (>90\%) and fast photoinduced energy transfer (ken ≈ 6.2 × 109 s-1) is followed by efficient electron transfer (70\%, ket ≈ 6.6 × 109 s-1) from the pyrene units to the perylene bisimide moiety. The energy donor−acceptor distance, R = 8.6 Å, is calculated from the experimental energy transfer rate using Förster theory. Temperature-dependent time-resolved emission spectroscopy showed an increase of the acceptor emission lifetime with decreasing temperature. It also indicates the presence of different conformations because two different electron transfer barriers (0.08 and 0.42 eV) were found. These barrier values were corroborated by a theoretical analysis of the energetics of the process using Marcus theory, indicating average donor−acceptor distances of 4.5 Å (room temperature) to 11 Å (at low T).

  @article{doi:10.1021/jp0372688, abstract = {The synthesis and photophysical properties of a system consisting of a bay-functionalized perylene bisimide, containing four appended pyrene and two coordinating pyridine units, and its reference system are described. A complete study of their photophysical properties was obtained using UV−vis absorption, steady state and time-resolved emission, and femtosecond transient absorption. Analysis of the data, obtained from time-resolved emission and femtosecond transient absorption spectroscopy, showed the presence of both photoinduced electron and energy transfer processes. A high yield (>90\%) and fast photoinduced energy transfer (ken ≈ 6.2 × 109 s-1) is followed by efficient electron transfer (70\%, ket ≈ 6.6 × 109 s-1) from the pyrene units to the perylene bisimide moiety. The energy donor−acceptor distance, R = 8.6 Å, is calculated from the experimental energy transfer rate using Förster theory. Temperature-dependent time-resolved emission spectroscopy showed an increase of the acceptor emission lifetime with decreasing temperature. It also indicates the presence of different conformations because two different electron transfer barriers (0.08 and 0.42 eV) were found. These barrier values were corroborated by a theoretical analysis of the energetics of the process using Marcus theory, indicating average donor−acceptor distances of 4.5 Å (room temperature) to 11 Å (at low T).}, author = {Kaletaş, Başak Kükrer and Dobrawa, Rainer and Sautter, Armin and Würthner, Frank and Zimine, Mikhail and De Cola, Luisa and Williams, René M.}, journal = {The Journal of Physical Chemistry A}, keywords = {myown}, number = 11, pages = {1900-1909}, title = {Photoinduced Electron and Energy Transfer Processes in a Bichromophoric Pyrene−Perylene Bisimide System}, volume = 108, year = 2004 }

  %0 Journal Article %1 doi:10.1021/jp0372688 %A Kaletaş, Başak Kükrer %A Dobrawa, Rainer %A Sautter, Armin %A Würthner, Frank %A Zimine, Mikhail %A De Cola, Luisa %A Williams, René M. %D 2004 %J The Journal of Physical Chemistry A %N 11 %P 1900-1909 %R 10.1021/jp0372688 %T Photoinduced Electron and Energy Transfer Processes in a Bichromophoric Pyrene−Perylene Bisimide System %U http://dx.doi.org/10.1021/jp0372688 %V 108 %X The synthesis and photophysical properties of a system consisting of a bay-functionalized perylene bisimide, containing four appended pyrene and two coordinating pyridine units, and its reference system are described. A complete study of their photophysical properties was obtained using UV−vis absorption, steady state and time-resolved emission, and femtosecond transient absorption. Analysis of the data, obtained from time-resolved emission and femtosecond transient absorption spectroscopy, showed the presence of both photoinduced electron and energy transfer processes. A high yield (>90\%) and fast photoinduced energy transfer (ken ≈ 6.2 × 109 s-1) is followed by efficient electron transfer (70\%, ket ≈ 6.6 × 109 s-1) from the pyrene units to the perylene bisimide moiety. The energy donor−acceptor distance, R = 8.6 Å, is calculated from the experimental energy transfer rate using Förster theory. Temperature-dependent time-resolved emission spectroscopy showed an increase of the acceptor emission lifetime with decreasing temperature. It also indicates the presence of different conformations because two different electron transfer barriers (0.08 and 0.42 eV) were found. These barrier values were corroborated by a theoretical analysis of the energetics of the process using Marcus theory, indicating average donor−acceptor distances of 4.5 Å (room temperature) to 11 Å (at low T).

• Merocyanine Dyes Containing Imide Functional Groups:  Synthesis and Studies on Hydrogen Bonding to Melamine Receptors. Würthner, Frank; Yao, Sheng. In The Journal of Organic Chemistry, 68(23), pp. 8943–8949. 2003.

  PMID: 14604366
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  The condensation of the CH acidic heterocycles 4-alkyl-2,6-dioxo-1,2,5,6-tetrahydropyridine-3-carbonitrile (5a and b) and barbituric acid (15) with electron-rich thiophene aldehydes and benzaldehyde derivatives affords the respective monomethine dyes 10−13 and 17−19. The formylation of 5a,b and 15 with N,N‘-diphenylformamidine or dibutylformamide in acetic anhydride and further reaction with 4-picolinium salts 9a,b provide the dimethine dyes 14 and 20a,b. Triple hydrogen bonding of the imide groups of merocyanine dyes 10−14 has been investigated by NMR titration experiments with melamine 21. Despite rather pronounced variations of the charge-transfer properties within the given series of dyes, minor changes of their binding constants have been observed. These results could be rationalized by semiempirical calculations that reveal small changes in the charge density at the oxygen functionalities involved in hydrogen bonding upon variation of the electron-donating carbocyclic or heterocyclic groups at the terminal double bond. Although the binding constants for triple hydrogen bonding between imides and melamines are rather weak in chloroform, they proved to be strong enough to facilitate dissolution of some of these dyes in aliphatic solvents by coordination to amphiphilic melamines and dipolar aggregation. UV−vis spectral changes observed in methylcyclohexane vs chloroform suggest the formation of colloidal assemblies through noncovalent polymerization.

  @article{doi:10.1021/jo0351670, abstract = {The condensation of the CH acidic heterocycles 4-alkyl-2,6-dioxo-1,2,5,6-tetrahydropyridine-3-carbonitrile (5a and b) and barbituric acid (15) with electron-rich thiophene aldehydes and benzaldehyde derivatives affords the respective monomethine dyes 10−13 and 17−19. The formylation of 5a,b and 15 with N,N‘-diphenylformamidine or dibutylformamide in acetic anhydride and further reaction with 4-picolinium salts 9a,b provide the dimethine dyes 14 and 20a,b. Triple hydrogen bonding of the imide groups of merocyanine dyes 10−14 has been investigated by NMR titration experiments with melamine 21. Despite rather pronounced variations of the charge-transfer properties within the given series of dyes, minor changes of their binding constants have been observed. These results could be rationalized by semiempirical calculations that reveal small changes in the charge density at the oxygen functionalities involved in hydrogen bonding upon variation of the electron-donating carbocyclic or heterocyclic groups at the terminal double bond. Although the binding constants for triple hydrogen bonding between imides and melamines are rather weak in chloroform, they proved to be strong enough to facilitate dissolution of some of these dyes in aliphatic solvents by coordination to amphiphilic melamines and dipolar aggregation. UV−vis spectral changes observed in methylcyclohexane vs chloroform suggest the formation of colloidal assemblies through noncovalent polymerization.}, author = {Würthner, Frank and Yao, Sheng}, journal = {The Journal of Organic Chemistry}, keywords = {myown}, note = {PMID: 14604366}, number = 23, pages = {8943-8949}, title = {Merocyanine Dyes Containing Imide Functional Groups:  Synthesis and Studies on Hydrogen Bonding to Melamine Receptors}, volume = 68, year = 2003 }

  %0 Journal Article %1 doi:10.1021/jo0351670 %A Würthner, Frank %A Yao, Sheng %D 2003 %J The Journal of Organic Chemistry %N 23 %P 8943-8949 %R 10.1021/jo0351670 %T Merocyanine Dyes Containing Imide Functional Groups:  Synthesis and Studies on Hydrogen Bonding to Melamine Receptors %U http://dx.doi.org/10.1021/jo0351670 %V 68 %X The condensation of the CH acidic heterocycles 4-alkyl-2,6-dioxo-1,2,5,6-tetrahydropyridine-3-carbonitrile (5a and b) and barbituric acid (15) with electron-rich thiophene aldehydes and benzaldehyde derivatives affords the respective monomethine dyes 10−13 and 17−19. The formylation of 5a,b and 15 with N,N‘-diphenylformamidine or dibutylformamide in acetic anhydride and further reaction with 4-picolinium salts 9a,b provide the dimethine dyes 14 and 20a,b. Triple hydrogen bonding of the imide groups of merocyanine dyes 10−14 has been investigated by NMR titration experiments with melamine 21. Despite rather pronounced variations of the charge-transfer properties within the given series of dyes, minor changes of their binding constants have been observed. These results could be rationalized by semiempirical calculations that reveal small changes in the charge density at the oxygen functionalities involved in hydrogen bonding upon variation of the electron-donating carbocyclic or heterocyclic groups at the terminal double bond. Although the binding constants for triple hydrogen bonding between imides and melamines are rather weak in chloroform, they proved to be strong enough to facilitate dissolution of some of these dyes in aliphatic solvents by coordination to amphiphilic melamines and dipolar aggregation. UV−vis spectral changes observed in methylcyclohexane vs chloroform suggest the formation of colloidal assemblies through noncovalent polymerization.
• Self-Assembly of Ferrocene-Functionalized Perylene Bisimide Bridging Ligands with Pt(II) Corner to Electrochemically Active Molecular Squares. You, Chang-Cheng; Würthner, Frank. In J. Am. Chem. Soc., 125(32), pp. 9716–9725. 2003.

  PMID: 12904037
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  Ferrocenyl-substituted N,N‘-di(4-pyridyl)perylene bisimide ligands have been synthesized by the coupling reaction of hydroxyphenoxy-perylene bisimides with ferrocenyl carboxylic acids. By means of metallosupramolecular self-assembly, hitherto unprecedented multiredox active dendritic molecular squares with 16 ferrocene groups positioned in the bridging ligands are prepared from the perylene bispyridyl imide ligands and [Pt(dppp)][(OTf)2] (dppp = 1,3-bis(diphenylphosphano)propane; OTf = trifluoromethanesulfonate) corner in high yield. The isolated metallosupramolecular squares were characterized by elemental analysis, 1H, 31P1H NMR, and UV/vis spectroscopy. The electrochemical properties of the ligands and squares are investigated by cyclic voltammetry as well as spectroelectrochemistry. The results obtained show that the redox behavior of ferrocene units is influenced by the square superstructure. Furthermore, redox titration of free ligand and corresponding molecular square with the one-electron oxidant thianthrenium pentachloroantimonate reveals that ferrocene groups in these structures may be oxidized completely by this oxidant, and highly charged species generated through oxidation of ferrocenyl groups in molecular square cause decomposition of the assembly due to pronounced Coulombic repulsion.

  @article{doi:10.1021/ja029648x, abstract = {Ferrocenyl-substituted N,N‘-di(4-pyridyl)perylene bisimide ligands have been synthesized by the coupling reaction of hydroxyphenoxy-perylene bisimides with ferrocenyl carboxylic acids. By means of metallosupramolecular self-assembly, hitherto unprecedented multiredox active dendritic molecular squares with 16 ferrocene groups positioned in the bridging ligands are prepared from the perylene bispyridyl imide ligands and [Pt(dppp)][(OTf)2] (dppp = 1,3-bis(diphenylphosphano)propane; OTf = trifluoromethanesulfonate) corner in high yield. The isolated metallosupramolecular squares were characterized by elemental analysis, 1H, 31P{1H} NMR, and UV/vis spectroscopy. The electrochemical properties of the ligands and squares are investigated by cyclic voltammetry as well as spectroelectrochemistry. The results obtained show that the redox behavior of ferrocene units is influenced by the square superstructure. Furthermore, redox titration of free ligand and corresponding molecular square with the one-electron oxidant thianthrenium pentachloroantimonate reveals that ferrocene groups in these structures may be oxidized completely by this oxidant, and highly charged species generated through oxidation of ferrocenyl groups in molecular square cause decomposition of the assembly due to pronounced Coulombic repulsion.}, author = {You, Chang-Cheng and Würthner, Frank}, journal = {J. Am. Chem. Soc.}, keywords = {myown}, note = {PMID: 12904037}, number = 32, pages = {9716-9725}, title = {Self-Assembly of Ferrocene-Functionalized Perylene Bisimide Bridging Ligands with Pt(II) Corner to Electrochemically Active Molecular Squares}, volume = 125, year = 2003 }

  %0 Journal Article %1 doi:10.1021/ja029648x %A You, Chang-Cheng %A Würthner, Frank %D 2003 %J J. Am. Chem. Soc. %N 32 %P 9716-9725 %R 10.1021/ja029648x %T Self-Assembly of Ferrocene-Functionalized Perylene Bisimide Bridging Ligands with Pt(II) Corner to Electrochemically Active Molecular Squares %U http://dx.doi.org/10.1021/ja029648x %V 125 %X Ferrocenyl-substituted N,N‘-di(4-pyridyl)perylene bisimide ligands have been synthesized by the coupling reaction of hydroxyphenoxy-perylene bisimides with ferrocenyl carboxylic acids. By means of metallosupramolecular self-assembly, hitherto unprecedented multiredox active dendritic molecular squares with 16 ferrocene groups positioned in the bridging ligands are prepared from the perylene bispyridyl imide ligands and [Pt(dppp)][(OTf)2] (dppp = 1,3-bis(diphenylphosphano)propane; OTf = trifluoromethanesulfonate) corner in high yield. The isolated metallosupramolecular squares were characterized by elemental analysis, 1H, 31P1H NMR, and UV/vis spectroscopy. The electrochemical properties of the ligands and squares are investigated by cyclic voltammetry as well as spectroelectrochemistry. The results obtained show that the redox behavior of ferrocene units is influenced by the square superstructure. Furthermore, redox titration of free ligand and corresponding molecular square with the one-electron oxidant thianthrenium pentachloroantimonate reveals that ferrocene groups in these structures may be oxidized completely by this oxidant, and highly charged species generated through oxidation of ferrocenyl groups in molecular square cause decomposition of the assembly due to pronounced Coulombic repulsion.
• Fabrication and fluorescence properties of perylene bisimide dye aggregates bound to gold surfaces and nanopatterns. Haas, Ulrike; Thalacker, Christoph; Adams, Jorg; Fuhrmann, Jurgen; Riethmuller, Silke; Beginn, Uwe; Ziener, Ulrich; Moller, Martin; Dobrawa, Rainer; Würthner, Frank. In J. Mater. Chem., 13(4), pp. 767–772. 2003.
  • [ Abstract ]
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  • [ DOI ]
  Perylene bisimide dyes with two different imide substituents have been synthesized by sequential imidization reactions to give the disulfide 8 bearing two perylene bisimide dyes. Aggregation properties of this bis-perylene dye were studied by UV/Vis absorption and steady-state polarization-dependent as well as time-resolved fluorescence spectroscopy and the results were compared to those of the symmetrical perylene bisimide dye 4. In both cases, aggregation is expressed in a strong bathochromic shift of the excitation and the emission spectra and increasing concentration results in an increase in lifetime from 5 to 8 ns. By means of the thiol linker, self-assembly of 8 on gold surfaces was accomplished leading to surface-bound dye aggregates. Intense fluorescence from these dye aggregates was observed on surfaces decorated with hexagonal gold patterns, whereas the fluorescence is only weak on plain gold substrates.

  @article{haas2003fabrication, abstract = {Perylene bisimide dyes with two different imide substituents have been synthesized by sequential imidization reactions to give the disulfide 8 bearing two perylene bisimide dyes. Aggregation properties of this bis-perylene dye were studied by UV/Vis absorption and steady-state polarization-dependent as well as time-resolved fluorescence spectroscopy and the results were compared to those of the symmetrical perylene bisimide dye 4. In both cases{,} aggregation is expressed in a strong bathochromic shift of the excitation and the emission spectra and increasing concentration results in an increase in lifetime from 5 to 8 ns. By means of the thiol linker{,} self-assembly of 8 on gold surfaces was accomplished leading to surface-bound dye aggregates. Intense fluorescence from these dye aggregates was observed on surfaces decorated with hexagonal gold patterns{,} whereas the fluorescence is only weak on plain gold substrates.}, author = {Haas, Ulrike and Thalacker, Christoph and Adams, Jorg and Fuhrmann, Jurgen and Riethmuller, Silke and Beginn, Uwe and Ziener, Ulrich and Moller, Martin and Dobrawa, Rainer and Würthner, Frank}, journal = {J. Mater. Chem.}, keywords = {myown}, number = 4, pages = {767-772}, publisher = {The Royal Society of Chemistry}, title = {Fabrication and fluorescence properties of perylene bisimide dye aggregates bound to gold surfaces and nanopatterns}, volume = 13, year = 2003 }

  %0 Journal Article %1 haas2003fabrication %A Haas, Ulrike %A Thalacker, Christoph %A Adams, Jorg %A Fuhrmann, Jurgen %A Riethmuller, Silke %A Beginn, Uwe %A Ziener, Ulrich %A Moller, Martin %A Dobrawa, Rainer %A Würthner, Frank %D 2003 %I The Royal Society of Chemistry %J J. Mater. Chem. %N 4 %P 767-772 %R 10.1039/B210423G %T Fabrication and fluorescence properties of perylene bisimide dye aggregates bound to gold surfaces and nanopatterns %U http://dx.doi.org/10.1039/B210423G %V 13 %X Perylene bisimide dyes with two different imide substituents have been synthesized by sequential imidization reactions to give the disulfide 8 bearing two perylene bisimide dyes. Aggregation properties of this bis-perylene dye were studied by UV/Vis absorption and steady-state polarization-dependent as well as time-resolved fluorescence spectroscopy and the results were compared to those of the symmetrical perylene bisimide dye 4. In both cases, aggregation is expressed in a strong bathochromic shift of the excitation and the emission spectra and increasing concentration results in an increase in lifetime from 5 to 8 ns. By means of the thiol linker, self-assembly of 8 on gold surfaces was accomplished leading to surface-bound dye aggregates. Intense fluorescence from these dye aggregates was observed on surfaces decorated with hexagonal gold patterns, whereas the fluorescence is only weak on plain gold substrates.
• Energy transfer in multichromophoric self-assembled molecular squares. Würthner, Frank; Sautter, Armin. In Org. Biomol. Chem., 1(2), pp. 240–243. 2003.
  • [ Abstract ]
  • [ BibTeX ]
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  Metal-ion directed self-assembly afforded well-defined molecular squares with a mass of 12 kDa incorporating four perylene bisimide and sixteen pyrene chromophores organized in a circular way. Energy transfer from the pyrene to the perylene dye manifold is investigated by emission and excitation spectroscopy.

  @article{wrthner2003energy, abstract = {Metal-ion directed self-assembly afforded well-defined molecular squares with a mass of 12 kDa incorporating four perylene bisimide and sixteen pyrene chromophores organized in a circular way. Energy transfer from the pyrene to the perylene dye manifold is investigated by emission and excitation spectroscopy.}, author = {Würthner, Frank and Sautter, Armin}, journal = {Org. Biomol. Chem.}, keywords = {myown}, number = 2, pages = {240-243}, publisher = {The Royal Society of Chemistry}, title = {Energy transfer in multichromophoric self-assembled molecular squares}, volume = 1, year = 2003 }

  %0 Journal Article %1 wrthner2003energy %A Würthner, Frank %A Sautter, Armin %D 2003 %I The Royal Society of Chemistry %J Org. Biomol. Chem. %N 2 %P 240-243 %R 10.1039/B208582H %T Energy transfer in multichromophoric self-assembled molecular squares %U http://dx.doi.org/10.1039/B208582H %V 1 %X Metal-ion directed self-assembly afforded well-defined molecular squares with a mass of 12 kDa incorporating four perylene bisimide and sixteen pyrene chromophores organized in a circular way. Energy transfer from the pyrene to the perylene dye manifold is investigated by emission and excitation spectroscopy.
• Highly Ordered Merocyanine Dye Assemblies by Supramolecular Polymerization and Hierarchical Self-Organization. Würthner, Frank; Yao, Sheng; Beginn, Uwe. In Angew. Chem. Int. Ed., 42(28), pp. 3247–3250. 2003.
  • [ BibTeX ]
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  @article{ANIE:ANIE200351414, author = {Würthner, Frank and Yao, Sheng and Beginn, Uwe}, journal = {Angew. Chem. Int. Ed.}, keywords = {myown}, number = 28, pages = {3247–3250}, publisher = {WILEY-VCH Verlag}, title = {Highly Ordered Merocyanine Dye Assemblies by Supramolecular Polymerization and Hierarchical Self-Organization}, volume = 42, year = 2003 }

  %0 Journal Article %1 ANIE:ANIE200351414 %A Würthner, Frank %A Yao, Sheng %A Beginn, Uwe %D 2003 %I WILEY-VCH Verlag %J Angew. Chem. Int. Ed. %N 28 %P 3247--3250 %R 10.1002/anie.200351414 %T Highly Ordered Merocyanine Dye Assemblies by Supramolecular Polymerization and Hierarchical Self-Organization %U http://dx.doi.org/10.1002/anie.200351414 %V 42
• Fabrication and fluorescence properties of perylene bisimide dye aggregates bound to gold surfaces and nanopatterns. Haas, Ulrike; Thalacker, Christoph; Adams, Jorg; Fuhrmann, Jurgen; Riethmuller, Silke; Beginn, Uwe; Ziener, Ulrich; Moller, Martin; Dobrawa, Rainer; Würthner, Frank. In J. Mater. Chem., 13(4), pp. 767–772. 2003.
  • [ Abstract ]
  • [ BibTeX ]
  • [ EndNote ]
  • [ DOI ]
  Perylene bisimide dyes with two different imide substituents have been synthesized by sequential imidization reactions to give the disulfide 8 bearing two perylene bisimide dyes. Aggregation properties of this bis-perylene dye were studied by UV/Vis absorption and steady-state polarization-dependent as well as time-resolved fluorescence spectroscopy and the results were compared to those of the symmetrical perylene bisimide dye 4. In both cases, aggregation is expressed in a strong bathochromic shift of the excitation and the emission spectra and increasing concentration results in an increase in lifetime from 5 to 8 ns. By means of the thiol linker, self-assembly of 8 on gold surfaces was accomplished leading to surface-bound dye aggregates. Intense fluorescence from these dye aggregates was observed on surfaces decorated with hexagonal gold patterns, whereas the fluorescence is only weak on plain gold substrates.

  @article{haas2003fabrication, abstract = {Perylene bisimide dyes with two different imide substituents have been synthesized by sequential imidization reactions to give the disulfide 8 bearing two perylene bisimide dyes. Aggregation properties of this bis-perylene dye were studied by UV/Vis absorption and steady-state polarization-dependent as well as time-resolved fluorescence spectroscopy and the results were compared to those of the symmetrical perylene bisimide dye 4. In both cases{,} aggregation is expressed in a strong bathochromic shift of the excitation and the emission spectra and increasing concentration results in an increase in lifetime from 5 to 8 ns. By means of the thiol linker{,} self-assembly of 8 on gold surfaces was accomplished leading to surface-bound dye aggregates. Intense fluorescence from these dye aggregates was observed on surfaces decorated with hexagonal gold patterns{,} whereas the fluorescence is only weak on plain gold substrates.}, author = {Haas, Ulrike and Thalacker, Christoph and Adams, Jorg and Fuhrmann, Jurgen and Riethmuller, Silke and Beginn, Uwe and Ziener, Ulrich and Moller, Martin and Dobrawa, Rainer and Würthner, Frank}, journal = {J. Mater. Chem.}, keywords = {myown}, number = 4, pages = {767-772}, publisher = {The Royal Society of Chemistry}, title = {Fabrication and fluorescence properties of perylene bisimide dye aggregates bound to gold surfaces and nanopatterns}, volume = 13, year = 2003 }

  %0 Journal Article %1 haas2003fabrication %A Haas, Ulrike %A Thalacker, Christoph %A Adams, Jorg %A Fuhrmann, Jurgen %A Riethmuller, Silke %A Beginn, Uwe %A Ziener, Ulrich %A Moller, Martin %A Dobrawa, Rainer %A Würthner, Frank %D 2003 %I The Royal Society of Chemistry %J J. Mater. Chem. %N 4 %P 767-772 %R 10.1039/B210423G %T Fabrication and fluorescence properties of perylene bisimide dye aggregates bound to gold surfaces and nanopatterns %U http://dx.doi.org/10.1039/B210423G %V 13 %X Perylene bisimide dyes with two different imide substituents have been synthesized by sequential imidization reactions to give the disulfide 8 bearing two perylene bisimide dyes. Aggregation properties of this bis-perylene dye were studied by UV/Vis absorption and steady-state polarization-dependent as well as time-resolved fluorescence spectroscopy and the results were compared to those of the symmetrical perylene bisimide dye 4. In both cases, aggregation is expressed in a strong bathochromic shift of the excitation and the emission spectra and increasing concentration results in an increase in lifetime from 5 to 8 ns. By means of the thiol linker, self-assembly of 8 on gold surfaces was accomplished leading to surface-bound dye aggregates. Intense fluorescence from these dye aggregates was observed on surfaces decorated with hexagonal gold patterns, whereas the fluorescence is only weak on plain gold substrates.
• Energy transfer in multichromophoric self-assembled molecular squares. Würthner, Frank; Sautter, Armin. In Org. Biomol. Chem., 1(2), pp. 240–243. 2003.
  • [ Abstract ]
  • [ BibTeX ]
  • [ EndNote ]
  • [ DOI ]
  Metal-ion directed self-assembly afforded well-defined molecular squares with a mass of 12 kDa incorporating four perylene bisimide and sixteen pyrene chromophores organized in a circular way. Energy transfer from the pyrene to the perylene dye manifold is investigated by emission and excitation spectroscopy.

  @article{wrthner2003energy, abstract = {Metal-ion directed self-assembly afforded well-defined molecular squares with a mass of 12 kDa incorporating four perylene bisimide and sixteen pyrene chromophores organized in a circular way. Energy transfer from the pyrene to the perylene dye manifold is investigated by emission and excitation spectroscopy.}, author = {Würthner, Frank and Sautter, Armin}, journal = {Org. Biomol. Chem.}, keywords = {myown}, number = 2, pages = {240-243}, publisher = {The Royal Society of Chemistry}, title = {Energy transfer in multichromophoric self-assembled molecular squares}, volume = 1, year = 2003 }

  %0 Journal Article %1 wrthner2003energy %A Würthner, Frank %A Sautter, Armin %D 2003 %I The Royal Society of Chemistry %J Org. Biomol. Chem. %N 2 %P 240-243 %R 10.1039/B208582H %T Energy transfer in multichromophoric self-assembled molecular squares %U http://dx.doi.org/10.1039/B208582H %V 1 %X Metal-ion directed self-assembly afforded well-defined molecular squares with a mass of 12 kDa incorporating four perylene bisimide and sixteen pyrene chromophores organized in a circular way. Energy transfer from the pyrene to the perylene dye manifold is investigated by emission and excitation spectroscopy.
• Large Electric-Field Effects on the Dipolar Aggregation of Merocyanine Dyes. Wortmann, Rüdiger; Rösch, Ulrich; Redi-Abshiro, Mesfin; Würthner, Frank. In Angew. Chem. Int. Ed., 42(18), pp. 2080–2083. 2003.
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  @article{ANIE:ANIE200250782, author = {Wortmann, Rüdiger and Rösch, Ulrich and Redi-Abshiro, Mesfin and Würthner, Frank}, journal = {Angew. Chem. Int. Ed.}, keywords = {myown}, number = 18, pages = {2080–2083}, publisher = {WILEY-VCH Verlag}, title = {Large Electric-Field Effects on the Dipolar Aggregation of Merocyanine Dyes}, volume = 42, year = 2003 }

  %0 Journal Article %1 ANIE:ANIE200250782 %A Wortmann, Rüdiger %A Rösch, Ulrich %A Redi-Abshiro, Mesfin %A Würthner, Frank %D 2003 %I WILEY-VCH Verlag %J Angew. Chem. Int. Ed. %N 18 %P 2080--2083 %R 10.1002/anie.200250782 %T Large Electric-Field Effects on the Dipolar Aggregation of Merocyanine Dyes %U http://dx.doi.org/10.1002/anie.200250782 %V 42
• Bias-Dependent Visualization of Electron Donor (D) and Electron Acceptor (A) Moieties in a Chiral DAD Triad Molecule. Miura, Atsushi; Chen, Zhijian; Uji i, Hiroshi; De Feyter, Steven; Zdanowska, Magdalena; Jonkheijm, Pascal; Schenning, Albertus P. H. J.; Meijer, E. W.; Würthner, Frank; De Schryver, Frans C. In J. Am. Chem. Soc., 125(49), pp. 14968–14969. 2003.

  PMID: 14653714
  • [ Abstract ]
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  The 2D crystal lattice structure and bias-dependent contrast of a chiral electron donor−acceptor−donor triad system, composed of two oligo(p-phenylene vinylene) electron donors and a perylenediimide electron acceptor (OPV4−PDI−OPV4), have been studied by means of scanning tunneling microscopy (STM) at the liquid−graphite interface. OPV4−PDI−OPV4 is ordered in rows and forms a well-ordered 2D crystal lattice structure. The electrical properties of the donor and acceptor parts are distinguished by the contrast in bias-dependent STM imaging.

  @article{doi:10.1021/ja037407z, abstract = {The 2D crystal lattice structure and bias-dependent contrast of a chiral electron donor−acceptor−donor triad system, composed of two oligo(p-phenylene vinylene) electron donors and a perylenediimide electron acceptor (OPV4−PDI−OPV4), have been studied by means of scanning tunneling microscopy (STM) at the liquid−graphite interface. OPV4−PDI−OPV4 is ordered in rows and forms a well-ordered 2D crystal lattice structure. The electrical properties of the donor and acceptor parts are distinguished by the contrast in bias-dependent STM imaging.}, author = {Miura, Atsushi and Chen, Zhijian and Uji i, Hiroshi and De Feyter, Steven and Zdanowska, Magdalena and Jonkheijm, Pascal and Schenning, Albertus P. H. J. and Meijer, E. W. and Würthner, Frank and De Schryver, Frans C.}, journal = {J. Am. Chem. Soc.}, keywords = {myown}, note = {PMID: 14653714}, number = 49, pages = {14968-14969}, title = {Bias-Dependent Visualization of Electron Donor (D) and Electron Acceptor (A) Moieties in a Chiral DAD Triad Molecule}, volume = 125, year = 2003 }

  %0 Journal Article %1 doi:10.1021/ja037407z %A Miura, Atsushi %A Chen, Zhijian %A Uji i, Hiroshi %A De Feyter, Steven %A Zdanowska, Magdalena %A Jonkheijm, Pascal %A Schenning, Albertus P. H. J. %A Meijer, E. W. %A Würthner, Frank %A De Schryver, Frans C. %D 2003 %J J. Am. Chem. Soc. %N 49 %P 14968-14969 %R 10.1021/ja037407z %T Bias-Dependent Visualization of Electron Donor (D) and Electron Acceptor (A) Moieties in a Chiral DAD Triad Molecule %U http://dx.doi.org/10.1021/ja037407z %V 125 %X The 2D crystal lattice structure and bias-dependent contrast of a chiral electron donor−acceptor−donor triad system, composed of two oligo(p-phenylene vinylene) electron donors and a perylenediimide electron acceptor (OPV4−PDI−OPV4), have been studied by means of scanning tunneling microscopy (STM) at the liquid−graphite interface. OPV4−PDI−OPV4 is ordered in rows and forms a well-ordered 2D crystal lattice structure. The electrical properties of the donor and acceptor parts are distinguished by the contrast in bias-dependent STM imaging.

• Hydrogen bond-directed aggregation of diazadibenzoperylene dyes in low-polarity solvents and the solid state. Sautter, Armin; Thalacker, Christoph; Heise, Bernd; Würthner, Frank. In Proceedings of the National Academy of Sciences, 99(8), pp. 4993–4996. 2002.
  • [ Abstract ]
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  The formation of complex superstructures via hydrogen bonding of two ditopic building blocks, diazadibenzoperylenes 1a,b and isophthalic acid 2, has been investigated. It was found that only the phenoxy-substituted diazadibenzoperylene 1a forms extended assemblies with 2 in complexes of a 1:1 stoichiometry, whereas for the 4-tert-butylphenoxy-substituted analogue 1b, no indications for superstructure formation with 2 were found. The different behavior is explained by the presence of additional π–π interactions, which are only observed for [1a⋅2], as revealed by concentration-dependent optical absorption and fluorescence spectroscopy. Based on variable temperature x-ray diffraction studies, a lamellar structure for [1a⋅2] is proposed that takes into account the concept of microphase-segregation.

  @article{Sautter16042002, abstract = {The formation of complex superstructures via hydrogen bonding of two ditopic building blocks, diazadibenzoperylenes 1a,b and isophthalic acid 2, has been investigated. It was found that only the phenoxy-substituted diazadibenzoperylene 1a forms extended assemblies with 2 in complexes of a 1:1 stoichiometry, whereas for the 4-tert-butylphenoxy-substituted analogue 1b, no indications for superstructure formation with 2 were found. The different behavior is explained by the presence of additional π–π interactions, which are only observed for [1a⋅2], as revealed by concentration-dependent optical absorption and fluorescence spectroscopy. Based on variable temperature x-ray diffraction studies, a lamellar structure for [1a⋅2] is proposed that takes into account the concept of microphase-segregation.}, author = {Sautter, Armin and Thalacker, Christoph and Heise, Bernd and Würthner, Frank}, journal = {Proceedings of the National Academy of Sciences}, keywords = {myown}, number = 8, pages = {4993-4996}, title = {Hydrogen bond-directed aggregation of diazadibenzoperylene dyes in low-polarity solvents and the solid state}, volume = 99, year = 2002 }

  %0 Journal Article %1 Sautter16042002 %A Sautter, Armin %A Thalacker, Christoph %A Heise, Bernd %A Würthner, Frank %D 2002 %J Proceedings of the National Academy of Sciences %N 8 %P 4993-4996 %R 10.1073/pnas.062606099 %T Hydrogen bond-directed aggregation of diazadibenzoperylene dyes in low-polarity solvents and the solid state %U http://www.pnas.org/content/99/8/4993.abstract %V 99 %X The formation of complex superstructures via hydrogen bonding of two ditopic building blocks, diazadibenzoperylenes 1a,b and isophthalic acid 2, has been investigated. It was found that only the phenoxy-substituted diazadibenzoperylene 1a forms extended assemblies with 2 in complexes of a 1:1 stoichiometry, whereas for the 4-tert-butylphenoxy-substituted analogue 1b, no indications for superstructure formation with 2 were found. The different behavior is explained by the presence of additional π–π interactions, which are only observed for [1a⋅2], as revealed by concentration-dependent optical absorption and fluorescence spectroscopy. Based on variable temperature x-ray diffraction studies, a lamellar structure for [1a⋅2] is proposed that takes into account the concept of microphase-segregation.
• Chiral Perylene Bisimide–Melamine Assemblies: Hydrogen Bond-Directed Growth of Helically Stacked Dyes with Chiroptical Properties. Thalacker, C.; Würthner, Frank. In Advanced Functional Materials, 12(3), pp. 209–218. 2002.
  • [ Abstract ]
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  Self-aggregation and hydrogen bond-directed superstructure formation with a perylene bisimide dye were investigated for melamines bearing two or four alkyl chains. For a melamine with two n-octadecyl substituents, large micellar aggregates of several hundred nanometers were observed in methylcyclohexane solution by dynamic light scattering. By means of hydrogen bonding these micelles were loaded with various contents of perylene bisimide dyes up to an equimolar amount. Even at low dye contents, islands of strongly aggregated perylene bisimides were formed according to UV-vis absorption spectroscopy. In a series of melamines functionalized with n-octadecyl esters of chiral amino acids, no self-aggregation of the melamines was observed, and the stability of the assemblies with the perylene bisimide dyes showed strong dependence on the melamine substituents. For four melamine–perylene bisimide combinations stable assemblies formed, which exhibited exciton-coupled circular dichroism (CD) effects for the perylene bisimide absorption bands whose sign is controlled by the stereoisomerism of the respective melamine. While for (S,S)-melamines a negative Cotton effect was observed, indicating an M-helical arrangement of the chromophores within the assembly, the (R,R)-enantiomer induced P-helicity, and no CD effect was found for the achiral (R,S)-diastereomer.

  @article{ADFM:ADFM209, abstract = {Self-aggregation and hydrogen bond-directed superstructure formation with a perylene bisimide dye were investigated for melamines bearing two or four alkyl chains. For a melamine with two n-octadecyl substituents, large micellar aggregates of several hundred nanometers were observed in methylcyclohexane solution by dynamic light scattering. By means of hydrogen bonding these micelles were loaded with various contents of perylene bisimide dyes up to an equimolar amount. Even at low dye contents, islands of strongly aggregated perylene bisimides were formed according to UV-vis absorption spectroscopy. In a series of melamines functionalized with n-octadecyl esters of chiral amino acids, no self-aggregation of the melamines was observed, and the stability of the assemblies with the perylene bisimide dyes showed strong dependence on the melamine substituents. For four melamine–perylene bisimide combinations stable assemblies formed, which exhibited exciton-coupled circular dichroism (CD) effects for the perylene bisimide absorption bands whose sign is controlled by the stereoisomerism of the respective melamine. While for (S,S)-melamines a negative Cotton effect was observed, indicating an M-helical arrangement of the chromophores within the assembly, the (R,R)-enantiomer induced P-helicity, and no CD effect was found for the achiral (R,S)-diastereomer.}, author = {Thalacker, C. and Würthner, Frank}, journal = {Advanced Functional Materials}, keywords = {myown}, number = 3, pages = {209–218}, publisher = {WILEY-VCH Verlag}, title = {Chiral Perylene Bisimide–Melamine Assemblies: Hydrogen Bond-Directed Growth of Helically Stacked Dyes with Chiroptical Properties}, volume = 12, year = 2002 }

  %0 Journal Article %1 ADFM:ADFM209 %A Thalacker, C. %A Würthner, Frank %D 2002 %I WILEY-VCH Verlag %J Advanced Functional Materials %N 3 %P 209--218 %R 10.1002/1616-3028(200203)12:3<209::AID-ADFM209>3.0.CO;2-Y %T Chiral Perylene Bisimide–Melamine Assemblies: Hydrogen Bond-Directed Growth of Helically Stacked Dyes with Chiroptical Properties %U http://dx.doi.org/10.1002/1616-3028(200203)12:3<209::AID-ADFM209>3.0.CO;2-Y %V 12 %X Self-aggregation and hydrogen bond-directed superstructure formation with a perylene bisimide dye were investigated for melamines bearing two or four alkyl chains. For a melamine with two n-octadecyl substituents, large micellar aggregates of several hundred nanometers were observed in methylcyclohexane solution by dynamic light scattering. By means of hydrogen bonding these micelles were loaded with various contents of perylene bisimide dyes up to an equimolar amount. Even at low dye contents, islands of strongly aggregated perylene bisimides were formed according to UV-vis absorption spectroscopy. In a series of melamines functionalized with n-octadecyl esters of chiral amino acids, no self-aggregation of the melamines was observed, and the stability of the assemblies with the perylene bisimide dyes showed strong dependence on the melamine substituents. For four melamine–perylene bisimide combinations stable assemblies formed, which exhibited exciton-coupled circular dichroism (CD) effects for the perylene bisimide absorption bands whose sign is controlled by the stereoisomerism of the respective melamine. While for (S,S)-melamines a negative Cotton effect was observed, indicating an M-helical arrangement of the chromophores within the assembly, the (R,R)-enantiomer induced P-helicity, and no CD effect was found for the achiral (R,S)-diastereomer.
• Photoinduced Electron Transfer in Hydrogen-Bonded Oligo(p-phenylene vinylene)−Perylene Bisimide Chiral Assemblies. Schenning, Albertus P. H. J.; v. Herrikhuyzen, Jeroen; Jonkheijm, Pascal; Chen, Zhijian; Würthner, Frank; Meijer, E. W. In J. Am. Chem. Soc., 124(35), pp. 10252–10253. 2002.

  PMID: 12197707
  • [ Abstract ]
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  Well-defined chiral fibers incorporating hydrogen-bonded oligo(p-phenylene vinylene) donor and perylene bisimide acceptor chromophores have been realized by self-assembly. Upon photoillumination of these fibers electron-transfer takes place, leading to charge separation within the aggregated dyes.

  @article{doi:10.1021/ja020378s, abstract = {Well-defined chiral fibers incorporating hydrogen-bonded oligo(p-phenylene vinylene) donor and perylene bisimide acceptor chromophores have been realized by self-assembly. Upon photoillumination of these fibers electron-transfer takes place, leading to charge separation within the aggregated dyes.}, author = {Schenning, Albertus P. H. J. and v. Herrikhuyzen, Jeroen and Jonkheijm, Pascal and Chen, Zhijian and Würthner, Frank and Meijer, E. W.}, journal = {J. Am. Chem. Soc.}, keywords = {myown}, note = {PMID: 12197707}, number = 35, pages = {10252-10253}, title = {Photoinduced Electron Transfer in Hydrogen-Bonded Oligo(p-phenylene vinylene)−Perylene Bisimide Chiral Assemblies}, volume = 124, year = 2002 }

  %0 Journal Article %1 doi:10.1021/ja020378s %A Schenning, Albertus P. H. J. %A v. Herrikhuyzen, Jeroen %A Jonkheijm, Pascal %A Chen, Zhijian %A Würthner, Frank %A Meijer, E. W. %D 2002 %J J. Am. Chem. Soc. %N 35 %P 10252-10253 %R 10.1021/ja020378s %T Photoinduced Electron Transfer in Hydrogen-Bonded Oligo(p-phenylene vinylene)−Perylene Bisimide Chiral Assemblies %U http://dx.doi.org/10.1021/ja020378s %V 124 %X Well-defined chiral fibers incorporating hydrogen-bonded oligo(p-phenylene vinylene) donor and perylene bisimide acceptor chromophores have been realized by self-assembly. Upon photoillumination of these fibers electron-transfer takes place, leading to charge separation within the aggregated dyes.
• Photoluminescent supramolecular polymers: metal-ion directed polymerization of terpyridine-functionalized perylene bisimide dyes. Dobrawa, Rainer; Würthner, Frank. In Chem. Commun., (17), pp. 1878–1879. 2002.
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  Perylene bisimide dyes bearing one and two 2,2[prime or minute][ratio]6[prime or minute],2[double prime]-terpyridine receptor groups were prepared and the structural and optical properties of their Zn2+ complexes were investigated by 1H NMR and fluorescence experiments.

  @article{B205478G, abstract = {Perylene bisimide dyes bearing one and two 2{,}2[prime or minute][ratio]6[prime or minute]{,}2[double prime]-terpyridine receptor groups were prepared and the structural and optical properties of their Zn2+ complexes were investigated by 1H NMR and fluorescence experiments.}, author = {Dobrawa, Rainer and Würthner, Frank}, journal = {Chem. Commun.}, keywords = {myown}, number = 17, pages = {1878-1879}, publisher = {The Royal Society of Chemistry}, title = {Photoluminescent supramolecular polymers: metal-ion directed polymerization of terpyridine-functionalized perylene bisimide dyes}, year = 2002 }

  %0 Journal Article %1 B205478G %A Dobrawa, Rainer %A Würthner, Frank %D 2002 %I The Royal Society of Chemistry %J Chem. Commun. %N 17 %P 1878-1879 %R 10.1039/B205478G %T Photoluminescent supramolecular polymers: metal-ion directed polymerization of terpyridine-functionalized perylene bisimide dyes %U http://dx.doi.org/10.1039/B205478G %X Perylene bisimide dyes bearing one and two 2,2[prime or minute][ratio]6[prime or minute],2[double prime]-terpyridine receptor groups were prepared and the structural and optical properties of their Zn2+ complexes were investigated by 1H NMR and fluorescence experiments.
• Dimerization of Merocyanine Dyes. Structural and Energetic Characterization of Dipolar Dye Aggregates and Implications for Nonlinear Optical Materials. Würthner, Frank; Yao, Sheng; Debaerdemaeker, Tony; Wortmann, Rüdiger. In J. Am. Chem. Soc., 124(32), pp. 9431–9447. 2002.

  PMID: 12167038
  • [ Abstract ]
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  Aggregation of polar merocyanine dyes has been identified as an important problem in the fabrication of organic materials for photonic applications. In this work, a series of merocyanine dyes is synthesized, and their aggregation is investigated by a combination of several experimental techniques to reveal structure−property relationships. These studies provide clear evidence for the formation of centrosymmetric dimers for all investigated merocyanines in concentrated solution and in the solid state. The thermodynamics of dimerization in liquid solution is studied by concentration-dependent permittivity measurements, UV−vis spectroscopy, and electrooptical absorption experiments. A centrosymmetric dimer structure with antiparallel ordering of the dipole moments is observed in solution by 2D NMR spectroscopy as well as in the solid state by X-ray crystallography and interpreted in terms of dipolar and π−π interactions. The optical properties of the dimer aggregates are satisfactorily explained by an excitonic coupling model. The effect of an external electric field on the dimerization equilibrium is considered and quantitatively determined by electrooptical absorption measurements. Implications of the observed findings on the design of nonlinear optical and photorefractive materials are discussed.

  @article{doi:10.1021/ja020168f, abstract = {Aggregation of polar merocyanine dyes has been identified as an important problem in the fabrication of organic materials for photonic applications. In this work, a series of merocyanine dyes is synthesized, and their aggregation is investigated by a combination of several experimental techniques to reveal structure−property relationships. These studies provide clear evidence for the formation of centrosymmetric dimers for all investigated merocyanines in concentrated solution and in the solid state. The thermodynamics of dimerization in liquid solution is studied by concentration-dependent permittivity measurements, UV−vis spectroscopy, and electrooptical absorption experiments. A centrosymmetric dimer structure with antiparallel ordering of the dipole moments is observed in solution by 2D NMR spectroscopy as well as in the solid state by X-ray crystallography and interpreted in terms of dipolar and π−π interactions. The optical properties of the dimer aggregates are satisfactorily explained by an excitonic coupling model. The effect of an external electric field on the dimerization equilibrium is considered and quantitatively determined by electrooptical absorption measurements. Implications of the observed findings on the design of nonlinear optical and photorefractive materials are discussed.}, author = {Würthner, Frank and Yao, Sheng and Debaerdemaeker, Tony and Wortmann, Rüdiger}, journal = {J. Am. Chem. Soc.}, keywords = {myown}, note = {PMID: 12167038}, number = 32, pages = {9431-9447}, title = {Dimerization of Merocyanine Dyes. Structural and Energetic Characterization of Dipolar Dye Aggregates and Implications for Nonlinear Optical Materials}, volume = 124, year = 2002 }

  %0 Journal Article %1 doi:10.1021/ja020168f %A Würthner, Frank %A Yao, Sheng %A Debaerdemaeker, Tony %A Wortmann, Rüdiger %D 2002 %J J. Am. Chem. Soc. %N 32 %P 9431-9447 %R 10.1021/ja020168f %T Dimerization of Merocyanine Dyes. Structural and Energetic Characterization of Dipolar Dye Aggregates and Implications for Nonlinear Optical Materials %U http://dx.doi.org/10.1021/ja020168f %V 124 %X Aggregation of polar merocyanine dyes has been identified as an important problem in the fabrication of organic materials for photonic applications. In this work, a series of merocyanine dyes is synthesized, and their aggregation is investigated by a combination of several experimental techniques to reveal structure−property relationships. These studies provide clear evidence for the formation of centrosymmetric dimers for all investigated merocyanines in concentrated solution and in the solid state. The thermodynamics of dimerization in liquid solution is studied by concentration-dependent permittivity measurements, UV−vis spectroscopy, and electrooptical absorption experiments. A centrosymmetric dimer structure with antiparallel ordering of the dipole moments is observed in solution by 2D NMR spectroscopy as well as in the solid state by X-ray crystallography and interpreted in terms of dipolar and π−π interactions. The optical properties of the dimer aggregates are satisfactorily explained by an excitonic coupling model. The effect of an external electric field on the dimerization equilibrium is considered and quantitatively determined by electrooptical absorption measurements. Implications of the observed findings on the design of nonlinear optical and photorefractive materials are discussed.
• Core-Substituted Naphthalene Bisimides: New Fluorophors with Tunable Emission Wavelength for FRET Studies. Würthner, Frank; Ahmed, Shahadat; Thalacker, Christoph; Debaerdemaeker, Tony. In Chemistry – A European Journal, 8(20), pp. 4742–4750. 2002.
  • [ Abstract ]
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  Highly colored and photoluminescent naphthalene bisimide dyes have been synthesized from 2,6-dichloronaphthalene bisanhydride 1 by means of a stepwise nucleophilic displacement of the two chlorine atoms by alkoxides and/or alkyl amines. The alkoxy-substituted derivatives are yellow dyes with green emission and low photoluminescence quantum yields, whereas the amine-substituted derivatives exhibit a color range from red to blue with strong photoluminescence up to 76 %. Structure–property relationships for this class of two-dimensional chromophores were evaluated based on a single-crystal X-ray analysis for dye 5 a, the observed solvatochromism, and quantum-chemical calculations. Owing to the simple tuning of the absorption properties over the whole visible range by the respective substituents, the pronounced brilliancy, and the intense photoluminescence, this class of dyes is considered to be highly suited for numerous applications such as fluorescent labeling of biomacromolecules and light-harvesting in supramolecular assemblies. As an important step towards such applications efficient FRET (fluorescence resonance energy transfer) has been demonstrated for a covalently tethered bichromophoric compound that contains a red and a blue naphthalene bisimide dye.

  @article{CHEM:CHEM4742, abstract = {Highly colored and photoluminescent naphthalene bisimide dyes have been synthesized from 2,6-dichloronaphthalene bisanhydride 1 by means of a stepwise nucleophilic displacement of the two chlorine atoms by alkoxides and/or alkyl amines. The alkoxy-substituted derivatives are yellow dyes with green emission and low photoluminescence quantum yields, whereas the amine-substituted derivatives exhibit a color range from red to blue with strong photoluminescence up to 76 %. Structure–property relationships for this class of two-dimensional chromophores were evaluated based on a single-crystal X-ray analysis for dye 5 a, the observed solvatochromism, and quantum-chemical calculations. Owing to the simple tuning of the absorption properties over the whole visible range by the respective substituents, the pronounced brilliancy, and the intense photoluminescence, this class of dyes is considered to be highly suited for numerous applications such as fluorescent labeling of biomacromolecules and light-harvesting in supramolecular assemblies. As an important step towards such applications efficient FRET (fluorescence resonance energy transfer) has been demonstrated for a covalently tethered bichromophoric compound that contains a red and a blue naphthalene bisimide dye.}, author = {Würthner, Frank and Ahmed, Shahadat and Thalacker, Christoph and Debaerdemaeker, Tony}, journal = {Chemistry – A European Journal}, keywords = {myown}, number = 20, pages = {4742–4750}, publisher = {WILEY-VCH Verlag}, title = {Core-Substituted Naphthalene Bisimides: New Fluorophors with Tunable Emission Wavelength for FRET Studies}, volume = 8, year = 2002 }

  %0 Journal Article %1 CHEM:CHEM4742 %A Würthner, Frank %A Ahmed, Shahadat %A Thalacker, Christoph %A Debaerdemaeker, Tony %D 2002 %I WILEY-VCH Verlag %J Chemistry – A European Journal %N 20 %P 4742--4750 %R 10.1002/1521-3765(20021018)8:20<4742::AID-CHEM4742>3.0.CO;2-L %T Core-Substituted Naphthalene Bisimides: New Fluorophors with Tunable Emission Wavelength for FRET Studies %U http://dx.doi.org/10.1002/1521-3765(20021018)8:20<4742::AID-CHEM4742>3.0.CO;2-L %V 8 %X Highly colored and photoluminescent naphthalene bisimide dyes have been synthesized from 2,6-dichloronaphthalene bisanhydride 1 by means of a stepwise nucleophilic displacement of the two chlorine atoms by alkoxides and/or alkyl amines. The alkoxy-substituted derivatives are yellow dyes with green emission and low photoluminescence quantum yields, whereas the amine-substituted derivatives exhibit a color range from red to blue with strong photoluminescence up to 76 %. Structure–property relationships for this class of two-dimensional chromophores were evaluated based on a single-crystal X-ray analysis for dye 5 a, the observed solvatochromism, and quantum-chemical calculations. Owing to the simple tuning of the absorption properties over the whole visible range by the respective substituents, the pronounced brilliancy, and the intense photoluminescence, this class of dyes is considered to be highly suited for numerous applications such as fluorescent labeling of biomacromolecules and light-harvesting in supramolecular assemblies. As an important step towards such applications efficient FRET (fluorescence resonance energy transfer) has been demonstrated for a covalently tethered bichromophoric compound that contains a red and a blue naphthalene bisimide dye.
• Photorefractive Organic Glasses based on a New Chromophore with Minimized Aggregation Tendency. Wortmann, R.; Redi-Abshiro, M.; Rösch, U.; Yao, S.; Würthner, F. In Proc. SPIE, 4802, pp. 1–7. 2002.
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  @article{wortmann2002photorefractive, author = {Wortmann, R. and Redi-Abshiro, M. and Rösch, U. and Yao, S. and Würthner, F.}, journal = {Proc. SPIE}, keywords = {myown}, pages = {1-7}, title = {Photorefractive Organic Glasses based on a New Chromophore with Minimized Aggregation Tendency.}, volume = 4802, year = 2002 }

  %0 Journal Article %1 wortmann2002photorefractive %A Wortmann, R. %A Redi-Abshiro, M. %A Rösch, U. %A Yao, S. %A Würthner, F. %D 2002 %J Proc. SPIE %P 1-7 %T Photorefractive Organic Glasses based on a New Chromophore with Minimized Aggregation Tendency. %V 4802
• Chromophore Design for Photorefractive Organic Materials. Würthner, Frank; Wortmann, Rüdiger; Meerholz, Klaus. In ChemPhysChem, 3(1), pp. 17–31. 2002.
  • [ Abstract ]
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  • [ DOI ]
  During the last years, significant progress has been achieved in understanding the mechanism of the photorefractive effect in amorphous organic materials. New chromophores could be devised which provided a substantial increase in the electrooptical response and lead to photorefractive materials with unprecedented refractive index modulation (Δn=10−2at E=28 V μm−1) and two-beam coupling gain. These improvements could only be accomplished by optimizing the electronic structure of highly conjugated merocyanine dyes to perfectly balanced dyes in the charge resonance limit (such as aminothienyl oxopyridone (ATOP) and indoline dimethine oxopyridone (IDOP) derivatives), considering effects of supramolecular ordering (dipolar aggregation), and adjusting the compatibility of the dyes to photoconducting polymers (like poly-N-vinylcarbazole). In particular, optimized glass-forming dyes (such as 2BNCM and ATOP-4) combine the dual functionalities of charge transport and electrooptical response and exhibit photorefractivity even in absence of any additional photoconductor.

  @article{CPHC:CPHC17, abstract = {During the last years, significant progress has been achieved in understanding the mechanism of the photorefractive effect in amorphous organic materials. New chromophores could be devised which provided a substantial increase in the electrooptical response and lead to photorefractive materials with unprecedented refractive index modulation (Δn=10−2at E=28 V μm−1) and two-beam coupling gain. These improvements could only be accomplished by optimizing the electronic structure of highly conjugated merocyanine dyes to perfectly balanced dyes in the charge resonance limit (such as aminothienyl oxopyridone (ATOP) and indoline dimethine oxopyridone (IDOP) derivatives), considering effects of supramolecular ordering (dipolar aggregation), and adjusting the compatibility of the dyes to photoconducting polymers (like poly-N-vinylcarbazole). In particular, optimized glass-forming dyes (such as 2BNCM and ATOP-4) combine the dual functionalities of charge transport and electrooptical response and exhibit photorefractivity even in absence of any additional photoconductor.}, author = {Würthner, Frank and Wortmann, Rüdiger and Meerholz, Klaus}, journal = {ChemPhysChem}, keywords = {myown}, number = 1, pages = {17–31}, publisher = {WILEY-VCH Verlag GmbH}, title = {Chromophore Design for Photorefractive Organic Materials}, volume = 3, year = 2002 }

  %0 Journal Article %1 CPHC:CPHC17 %A Würthner, Frank %A Wortmann, Rüdiger %A Meerholz, Klaus %D 2002 %I WILEY-VCH Verlag GmbH %J ChemPhysChem %N 1 %P 17--31 %R 10.1002/1439-7641(20020118)3:1<17::AID-CPHC17>3.0.CO;2-N %T Chromophore Design for Photorefractive Organic Materials %U http://dx.doi.org/10.1002/1439-7641(20020118)3:1<17::AID-CPHC17>3.0.CO;2-N %V 3 %X During the last years, significant progress has been achieved in understanding the mechanism of the photorefractive effect in amorphous organic materials. New chromophores could be devised which provided a substantial increase in the electrooptical response and lead to photorefractive materials with unprecedented refractive index modulation (Δn=10−2at E=28 V μm−1) and two-beam coupling gain. These improvements could only be accomplished by optimizing the electronic structure of highly conjugated merocyanine dyes to perfectly balanced dyes in the charge resonance limit (such as aminothienyl oxopyridone (ATOP) and indoline dimethine oxopyridone (IDOP) derivatives), considering effects of supramolecular ordering (dipolar aggregation), and adjusting the compatibility of the dyes to photoconducting polymers (like poly-N-vinylcarbazole). In particular, optimized glass-forming dyes (such as 2BNCM and ATOP-4) combine the dual functionalities of charge transport and electrooptical response and exhibit photorefractivity even in absence of any additional photoconductor.
• Calix[4]arene-Functionalized Naphthalene and Perylene Imide Dyes. Vysotsky, Myroslav O.; Böhmer, Volker; Würthner, Frank; You, Chang-Cheng; Rissanen, Kari. In Organic Letters, 4(17), pp. 2901–2904. 2002.

  PMID: 12182584
  • [ Abstract ]
  • [ BibTeX ]
  • [ EndNote ]
  • [ DOI ]
  Calix[4]arenes bearing one, two, or four 1,8-naphthyl imide groups at the wide rim and bis-calix[4]arenes connected via perylene-bisimide dye spacers have been synthesized. The low-temperature NMR spectrum of the tetranaphthylimide suggests, in agreement with a crystal structure, a C2-symmetrical pinched cone conformation stabilized via face-to-face π−π interactions between opposite naphthylimide groups. UV−vis and fluorescence studies have been carried out for the perylene bis-calix[4]arene dyes.

  @article{doi:10.1021/ol026402o, abstract = {Calix[4]arenes bearing one, two, or four 1,8-naphthyl imide groups at the wide rim and bis-calix[4]arenes connected via perylene-bisimide dye spacers have been synthesized. The low-temperature NMR spectrum of the tetranaphthylimide suggests, in agreement with a crystal structure, a C2-symmetrical pinched cone conformation stabilized via face-to-face π−π interactions between opposite naphthylimide groups. UV−vis and fluorescence studies have been carried out for the perylene bis-calix[4]arene dyes.}, author = {Vysotsky, Myroslav O. and Böhmer, Volker and Würthner, Frank and You, Chang-Cheng and Rissanen, Kari}, journal = {Organic Letters}, keywords = {myown}, note = {PMID: 12182584}, number = 17, pages = {2901-2904}, title = {Calix[4]arene-Functionalized Naphthalene and Perylene Imide Dyes}, volume = 4, year = 2002 }

  %0 Journal Article %1 doi:10.1021/ol026402o %A Vysotsky, Myroslav O. %A Böhmer, Volker %A Würthner, Frank %A You, Chang-Cheng %A Rissanen, Kari %D 2002 %J Organic Letters %N 17 %P 2901-2904 %R 10.1021/ol026402o %T Calix[4]arene-Functionalized Naphthalene and Perylene Imide Dyes %U http://dx.doi.org/10.1021/ol026402o %V 4 %X Calix[4]arenes bearing one, two, or four 1,8-naphthyl imide groups at the wide rim and bis-calix[4]arenes connected via perylene-bisimide dye spacers have been synthesized. The low-temperature NMR spectrum of the tetranaphthylimide suggests, in agreement with a crystal structure, a C2-symmetrical pinched cone conformation stabilized via face-to-face π−π interactions between opposite naphthylimide groups. UV−vis and fluorescence studies have been carried out for the perylene bis-calix[4]arene dyes.
• Efficient Synthesis of a Multifunctional Dye Conjugate for Photorefractive Applications. Yaoa, Sheng; Hohleb, Christoph; Strohrieglb, Peter; Würthner, Frank. In Synthesis, pp. 1143–1146. 2002.
  • [ BibTeX ]
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  • [ DOI ]
  @article{noauthororeditor, author = {Yaoa, Sheng and Hohleb, Christoph and Strohrieglb, Peter and Würthner, Frank}, journal = {Synthesis}, keywords = {myown}, pages = {1143–1146}, title = {Efficient Synthesis of a Multifunctional Dye Conjugate for Photorefractive Applications}, year = 2002 }

  %0 Journal Article %1 noauthororeditor %A Yaoa, Sheng %A Hohleb, Christoph %A Strohrieglb, Peter %A Würthner, Frank %D 2002 %J Synthesis %P 1143–1146 %R 10.1055/s-2002-32522 %T Efficient Synthesis of a Multifunctional Dye Conjugate for Photorefractive Applications %U https://www.thieme-connect.de/DOI/DOI?10.1055/s-2002-32522
• Core-Substituted Naphthalene Bisimides: New Fluorophors with Tunable Emission Wavelength for FRET Studies. Würthner, Frank; Ahmed, Shahadat; Thalacker, Christoph; Debaerdemaeker, Tony. In Chemistry – A European Journal, 8(20), pp. 4742–4750. 2002.
  • [ Abstract ]
  • [ BibTeX ]
  • [ EndNote ]
  • [ DOI ]
  Highly colored and photoluminescent naphthalene bisimide dyes have been synthesized from 2,6-dichloronaphthalene bisanhydride 1 by means of a stepwise nucleophilic displacement of the two chlorine atoms by alkoxides and/or alkyl amines. The alkoxy-substituted derivatives are yellow dyes with green emission and low photoluminescence quantum yields, whereas the amine-substituted derivatives exhibit a color range from red to blue with strong photoluminescence up to 76 %. Structure–property relationships for this class of two-dimensional chromophores were evaluated based on a single-crystal X-ray analysis for dye 5 a, the observed solvatochromism, and quantum-chemical calculations. Owing to the simple tuning of the absorption properties over the whole visible range by the respective substituents, the pronounced brilliancy, and the intense photoluminescence, this class of dyes is considered to be highly suited for numerous applications such as fluorescent labeling of biomacromolecules and light-harvesting in supramolecular assemblies. As an important step towards such applications efficient FRET (fluorescence resonance energy transfer) has been demonstrated for a covalently tethered bichromophoric compound that contains a red and a blue naphthalene bisimide dye.

  @article{CHEM:CHEM4742, abstract = {Highly colored and photoluminescent naphthalene bisimide dyes have been synthesized from 2,6-dichloronaphthalene bisanhydride 1 by means of a stepwise nucleophilic displacement of the two chlorine atoms by alkoxides and/or alkyl amines. The alkoxy-substituted derivatives are yellow dyes with green emission and low photoluminescence quantum yields, whereas the amine-substituted derivatives exhibit a color range from red to blue with strong photoluminescence up to 76 %. Structure–property relationships for this class of two-dimensional chromophores were evaluated based on a single-crystal X-ray analysis for dye 5 a, the observed solvatochromism, and quantum-chemical calculations. Owing to the simple tuning of the absorption properties over the whole visible range by the respective substituents, the pronounced brilliancy, and the intense photoluminescence, this class of dyes is considered to be highly suited for numerous applications such as fluorescent labeling of biomacromolecules and light-harvesting in supramolecular assemblies. As an important step towards such applications efficient FRET (fluorescence resonance energy transfer) has been demonstrated for a covalently tethered bichromophoric compound that contains a red and a blue naphthalene bisimide dye.}, author = {Würthner, Frank and Ahmed, Shahadat and Thalacker, Christoph and Debaerdemaeker, Tony}, journal = {Chemistry – A European Journal}, keywords = {myown}, number = 20, pages = {4742–4750}, publisher = {WILEY-VCH Verlag}, title = {Core-Substituted Naphthalene Bisimides: New Fluorophors with Tunable Emission Wavelength for FRET Studies}, volume = 8, year = 2002 }

  %0 Journal Article %1 CHEM:CHEM4742 %A Würthner, Frank %A Ahmed, Shahadat %A Thalacker, Christoph %A Debaerdemaeker, Tony %D 2002 %I WILEY-VCH Verlag %J Chemistry – A European Journal %N 20 %P 4742--4750 %R 10.1002/1521-3765(20021018)8:20<4742::AID-CHEM4742>3.0.CO;2-L %T Core-Substituted Naphthalene Bisimides: New Fluorophors with Tunable Emission Wavelength for FRET Studies %U http://dx.doi.org/10.1002/1521-3765(20021018)8:20<4742::AID-CHEM4742>3.0.CO;2-L %V 8 %X Highly colored and photoluminescent naphthalene bisimide dyes have been synthesized from 2,6-dichloronaphthalene bisanhydride 1 by means of a stepwise nucleophilic displacement of the two chlorine atoms by alkoxides and/or alkyl amines. The alkoxy-substituted derivatives are yellow dyes with green emission and low photoluminescence quantum yields, whereas the amine-substituted derivatives exhibit a color range from red to blue with strong photoluminescence up to 76 %. Structure–property relationships for this class of two-dimensional chromophores were evaluated based on a single-crystal X-ray analysis for dye 5 a, the observed solvatochromism, and quantum-chemical calculations. Owing to the simple tuning of the absorption properties over the whole visible range by the respective substituents, the pronounced brilliancy, and the intense photoluminescence, this class of dyes is considered to be highly suited for numerous applications such as fluorescent labeling of biomacromolecules and light-harvesting in supramolecular assemblies. As an important step towards such applications efficient FRET (fluorescence resonance energy transfer) has been demonstrated for a covalently tethered bichromophoric compound that contains a red and a blue naphthalene bisimide dye.
• Efficient Synthesis of a Multifunctional Dye Conjugate for Photorefractive Applications. Yaoa, Sheng; Hohleb, Christoph; Strohrieglb, Peter; Würthner, Frank. In Synthesis, pp. 1143–1146. 2002.
  • [ BibTeX ]
  • [ EndNote ]
  • [ DOI ]
  @article{noauthororeditor, author = {Yaoa, Sheng and Hohleb, Christoph and Strohrieglb, Peter and Würthner, Frank}, journal = {Synthesis}, keywords = {myown}, pages = {1143–1146}, title = {Efficient Synthesis of a Multifunctional Dye Conjugate for Photorefractive Applications}, year = 2002 }

  %0 Journal Article %1 noauthororeditor %A Yaoa, Sheng %A Hohleb, Christoph %A Strohrieglb, Peter %A Würthner, Frank %D 2002 %J Synthesis %P 1143–1146 %R 10.1055/s-2002-32522 %T Efficient Synthesis of a Multifunctional Dye Conjugate for Photorefractive Applications %U https://www.thieme-connect.de/DOI/DOI?10.1055/s-2002-32522
• Synthesis of Diazadibenzoperylenes and Characterization of Their Structural, Optical, Redox, and Coordination Properties. Würthner, Frank; Sautter, Armin; Schilling, Joachim. In The Journal of Organic Chemistry, 67(9), pp. 3037–3044. 2002.

  PMID: 11975564
  • [ Abstract ]
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  Tetraphenoxy-substituted diazadibenzoperylenes 5a,b were synthesized from tetrachloroperylene tetracarboxylic acid bisanhydride 1 through imidization with benzylamine, nucleophilic displacement of the four chlorine atoms by phenolates, carbonyl group reduction by LiAlH4/AlCl3, and subsequent Pd/C-promoted debenzylation−dehydrogenation. The structural properties of these extended diazaarenes are discussed on the basis of a X-ray crystal structure of the N,N‘-dibutylated diazadibenzoperylenium dication 6, which revealed a 25° twist of the central six-membered ring leading to an atropisomeric π-conjugated backbone. The chromophoric systems of 5 and 6 were characterized by optical absorption and fluorescence spectroscopy, which revealed an intense fluorescence with a quantum yield of 75\% for 5 and 50\% for 6. Cyclic voltammetry showed reversible oxidation and reduction waves for 6, whereas the oxidation of 5 afforded the irreversible deposition of a conductive film on the electrode surface. Finally, the potential use of ligands 5 in supramolecular chemistry has been evaluated by complexation experiments with carboxylic acids and zinc tetraphenylporphyrin (ZnTPP).

  @article{doi:10.1021/jo011133l, abstract = {Tetraphenoxy-substituted diazadibenzoperylenes 5a,b were synthesized from tetrachloroperylene tetracarboxylic acid bisanhydride 1 through imidization with benzylamine, nucleophilic displacement of the four chlorine atoms by phenolates, carbonyl group reduction by LiAlH4/AlCl3, and subsequent Pd/C-promoted debenzylation−dehydrogenation. The structural properties of these extended diazaarenes are discussed on the basis of a X-ray crystal structure of the N,N‘-dibutylated diazadibenzoperylenium dication 6, which revealed a 25° twist of the central six-membered ring leading to an atropisomeric π-conjugated backbone. The chromophoric systems of 5 and 6 were characterized by optical absorption and fluorescence spectroscopy, which revealed an intense fluorescence with a quantum yield of 75\% for 5 and 50\% for 6. Cyclic voltammetry showed reversible oxidation and reduction waves for 6, whereas the oxidation of 5 afforded the irreversible deposition of a conductive film on the electrode surface. Finally, the potential use of ligands 5 in supramolecular chemistry has been evaluated by complexation experiments with carboxylic acids and zinc tetraphenylporphyrin (ZnTPP).}, author = {Würthner, Frank and Sautter, Armin and Schilling, Joachim}, journal = {The Journal of Organic Chemistry}, keywords = {myown}, note = {PMID: 11975564}, number = 9, pages = {3037-3044}, title = {Synthesis of Diazadibenzoperylenes and Characterization of Their Structural, Optical, Redox, and Coordination Properties}, volume = 67, year = 2002 }

  %0 Journal Article %1 doi:10.1021/jo011133l %A Würthner, Frank %A Sautter, Armin %A Schilling, Joachim %D 2002 %J The Journal of Organic Chemistry %N 9 %P 3037-3044 %R 10.1021/jo011133l %T Synthesis of Diazadibenzoperylenes and Characterization of Their Structural, Optical, Redox, and Coordination Properties %U http://dx.doi.org/10.1021/jo011133l %V 67 %X Tetraphenoxy-substituted diazadibenzoperylenes 5a,b were synthesized from tetrachloroperylene tetracarboxylic acid bisanhydride 1 through imidization with benzylamine, nucleophilic displacement of the four chlorine atoms by phenolates, carbonyl group reduction by LiAlH4/AlCl3, and subsequent Pd/C-promoted debenzylation−dehydrogenation. The structural properties of these extended diazaarenes are discussed on the basis of a X-ray crystal structure of the N,N‘-dibutylated diazadibenzoperylenium dication 6, which revealed a 25° twist of the central six-membered ring leading to an atropisomeric π-conjugated backbone. The chromophoric systems of 5 and 6 were characterized by optical absorption and fluorescence spectroscopy, which revealed an intense fluorescence with a quantum yield of 75\% for 5 and 50\% for 6. Cyclic voltammetry showed reversible oxidation and reduction waves for 6, whereas the oxidation of 5 afforded the irreversible deposition of a conductive film on the electrode surface. Finally, the potential use of ligands 5 in supramolecular chemistry has been evaluated by complexation experiments with carboxylic acids and zinc tetraphenylporphyrin (ZnTPP).

• Kunststoff-Transistoren werden reif für Massenanwendungen in der Mikroelektronik. Würthner, Frank. In Angewandte Chemie, 113(6), pp. 1069–1071. 2001.
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  @article{ANGE:ANGE10690, author = {Würthner, Frank}, journal = {Angewandte Chemie}, keywords = {myown}, number = 6, pages = {1069–1071}, publisher = {WILEY-VCH Verlag GmbH}, title = {Kunststoff-Transistoren werden reif für Massenanwendungen in der Mikroelektronik}, volume = 113, year = 2001 }

  %0 Journal Article %1 ANGE:ANGE10690 %A Würthner, Frank %D 2001 %I WILEY-VCH Verlag GmbH %J Angewandte Chemie %N 6 %P 1069--1071 %R 10.1002/1521-3757(20010316)113:6<1069::AID-ANGE10690>3.0.CO;2-9 %T Kunststoff-Transistoren werden reif für Massenanwendungen in der Mikroelektronik %U http://dx.doi.org/10.1002/1521-3757(20010316)113:6<1069::AID-ANGE10690>3.0.CO;2-9 %V 113
• Chiral exciton coupling of merocyanine dyes within a well defined hydrogen-bonded assembly. Prins, Leonard J.; Thalacker, Christoph; Würthner, Frank; Timmerman, Peter; Reinhoudt, David N. In Proceedings of the National Academy of Sciences, 98(18), pp. 10042–10045. 2001.
  • [ Abstract ]
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  Multichromophoric hydrogen-bonded assemblies 13⋅(BAR)6 are studied that bear a remarkably close resemblance to commelinin, a naturally occurring assembly responsible for an intense blue color of flowers. The incorporated chromophores exhibit a hypsochromic shift in the UV/visible (Vis) absorption maximum (Δ λmax = 14 nm) compared with the free chromophores. In addition, the chiroptical properties of incorporated chromophores can be rationally controlled by changing the supramolecular chirality of the assembly. These properties have been used to study the stability of this type of assembly with UV and CD spectroscopy at concentrations far below the NMR sensitivity threshold (10−4 M). The determined C50% values of 2–3 μM in benzene show the extremely high stability of these hydrogen-bonded assemblies.

  @article{Prins28082001, abstract = {Multichromophoric hydrogen-bonded assemblies 13⋅(BAR)6 are studied that bear a remarkably close resemblance to commelinin, a naturally occurring assembly responsible for an intense blue color of flowers. The incorporated chromophores exhibit a hypsochromic shift in the UV/visible (Vis) absorption maximum (Δ λmax = 14 nm) compared with the free chromophores. In addition, the chiroptical properties of incorporated chromophores can be rationally controlled by changing the supramolecular chirality of the assembly. These properties have been used to study the stability of this type of assembly with UV and CD spectroscopy at concentrations far below the NMR sensitivity threshold (10−4 M). The determined C50% values of 2–3 μM in benzene show the extremely high stability of these hydrogen-bonded assemblies.}, author = {Prins, Leonard J. and Thalacker, Christoph and Würthner, Frank and Timmerman, Peter and Reinhoudt, David N.}, journal = {Proceedings of the National Academy of Sciences}, keywords = {myown}, number = 18, pages = {10042-10045}, title = {Chiral exciton coupling of merocyanine dyes within a well defined hydrogen-bonded assembly}, volume = 98, year = 2001 }

  %0 Journal Article %1 Prins28082001 %A Prins, Leonard J. %A Thalacker, Christoph %A Würthner, Frank %A Timmerman, Peter %A Reinhoudt, David N. %D 2001 %J Proceedings of the National Academy of Sciences %N 18 %P 10042-10045 %R 10.1073/pnas.171131398 %T Chiral exciton coupling of merocyanine dyes within a well defined hydrogen-bonded assembly %U http://www.pnas.org/content/98/18/10042.abstract %V 98 %X Multichromophoric hydrogen-bonded assemblies 13⋅(BAR)6 are studied that bear a remarkably close resemblance to commelinin, a naturally occurring assembly responsible for an intense blue color of flowers. The incorporated chromophores exhibit a hypsochromic shift in the UV/visible (Vis) absorption maximum (Δ λmax = 14 nm) compared with the free chromophores. In addition, the chiroptical properties of incorporated chromophores can be rationally controlled by changing the supramolecular chirality of the assembly. These properties have been used to study the stability of this type of assembly with UV and CD spectroscopy at concentrations far below the NMR sensitivity threshold (10−4 M). The determined C50% values of 2–3 μM in benzene show the extremely high stability of these hydrogen-bonded assemblies.
• Control of Liquid Crystallinity of Diazadibenzoperylene Dyes by Covalent and Hydrogen-Bonded Attachment of Mesogens. Sautter, Armin; Thalacker, Christoph; Würthner, Frank. In Angew. Chem. Int. Ed., 40(23), pp. 4425–4428. 2001.
  • [ BibTeX ]
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  @article{ANGE:ANGE4557, author = {Sautter, Armin and Thalacker, Christoph and Würthner, Frank}, journal = {Angew. Chem. Int. Ed.}, keywords = {myown}, number = 23, pages = {4425–4428}, publisher = {WILEY-VCH Verlag GmbH}, title = {Control of Liquid Crystallinity of Diazadibenzoperylene Dyes by Covalent and Hydrogen-Bonded Attachment of Mesogens}, volume = 40, year = 2001 }

  %0 Journal Article %1 ANGE:ANGE4557 %A Sautter, Armin %A Thalacker, Christoph %A Würthner, Frank %D 2001 %I WILEY-VCH Verlag GmbH %J Angew. Chem. Int. Ed. %N 23 %P 4425--4428 %R 10.1002/1521-3773(20011203)40%3A23<4425%3A%3AAID-ANIE4425>3.0.CO%3B2-Z %T Control of Liquid Crystallinity of Diazadibenzoperylene Dyes by Covalent and Hydrogen-Bonded Attachment of Mesogens %U https://onlinelibrary.wiley.com/doi/full/10.1002/1521-3773%2820011203%2940%3A23%3C4425%3A%3AAID-ANIE4425%3E3.0.CO%3B2-Z %V 40
• Fluorescent J-type Aggregates and Thermotropic Columnar Mesophases of Perylene Bisimide Dyes. Würthner, Frank; Thalacker, Christoph; Diele, Siegmar; Tschierske, Carsten. In Chemistry – A European Journal, 7(10), pp. 2245–2253. 2001.
  • [ Abstract ]
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  A series of perylene tetracarboxylic acid bisimides 3 a–e bearing 3,4,5-tridodecyloxyphenyl substituents on the imide N atoms and zero, two, or four phenoxy-type substituents in the bay positions of the perylene core were synthesized. From investigations of their spectroscopic properties and aggregation behavior in low-polarity solvents by absorption and fluorescence optical spectroscopy, not only were these compounds found to form fluorescent J-type aggregates, but also binding constants for aggregation could be derived which reflect the number and steric demand of the phenoxy substituents for bisimides 3 a–d. In the pristine state, 3 a–d form thermotropic hexagonal columnar mesophases which exist over a broad temperature range from below −30 °C to over 300 °C. For the tetraphenoxy-substituted compound 3 e, however, a layered crystalline structure was found. This difference in behavior can be explained by the concept of microphase segregation of the aromatic cores of the molecules and the alkyl chains at the periphery. The high stability and bright fluorescence of the mesophase of several of the compounds make them promising for applications as polarizers or components in (opto)electronic devices.

  @article{CHEM:CHEM2245, abstract = {A series of perylene tetracarboxylic acid bisimides 3 a–e bearing 3,4,5-tridodecyloxyphenyl substituents on the imide N atoms and zero, two, or four phenoxy-type substituents in the bay positions of the perylene core were synthesized. From investigations of their spectroscopic properties and aggregation behavior in low-polarity solvents by absorption and fluorescence optical spectroscopy, not only were these compounds found to form fluorescent J-type aggregates, but also binding constants for aggregation could be derived which reflect the number and steric demand of the phenoxy substituents for bisimides 3 a–d. In the pristine state, 3 a–d form thermotropic hexagonal columnar mesophases which exist over a broad temperature range from below −30 °C to over 300 °C. For the tetraphenoxy-substituted compound 3 e, however, a layered crystalline structure was found. This difference in behavior can be explained by the concept of microphase segregation of the aromatic cores of the molecules and the alkyl chains at the periphery. The high stability and bright fluorescence of the mesophase of several of the compounds make them promising for applications as polarizers or components in (opto)electronic devices.}, author = {Würthner, Frank and Thalacker, Christoph and Diele, Siegmar and Tschierske, Carsten}, journal = {Chemistry – A European Journal}, keywords = {myown}, number = 10, pages = {2245–2253}, publisher = {WILEY-VCH Verlag GmbH}, title = {Fluorescent J-type Aggregates and Thermotropic Columnar Mesophases of Perylene Bisimide Dyes}, volume = 7, year = 2001 }

  %0 Journal Article %1 CHEM:CHEM2245 %A Würthner, Frank %A Thalacker, Christoph %A Diele, Siegmar %A Tschierske, Carsten %D 2001 %I WILEY-VCH Verlag GmbH %J Chemistry – A European Journal %N 10 %P 2245--2253 %R 10.1002/1521-3765(20010518)7:10<2245::AID-CHEM2245>3.0.CO;2-W %T Fluorescent J-type Aggregates and Thermotropic Columnar Mesophases of Perylene Bisimide Dyes %U http://dx.doi.org/10.1002/1521-3765(20010518)7:10<2245::AID-CHEM2245>3.0.CO;2-W %V 7 %X A series of perylene tetracarboxylic acid bisimides 3 a–e bearing 3,4,5-tridodecyloxyphenyl substituents on the imide N atoms and zero, two, or four phenoxy-type substituents in the bay positions of the perylene core were synthesized. From investigations of their spectroscopic properties and aggregation behavior in low-polarity solvents by absorption and fluorescence optical spectroscopy, not only were these compounds found to form fluorescent J-type aggregates, but also binding constants for aggregation could be derived which reflect the number and steric demand of the phenoxy substituents for bisimides 3 a–d. In the pristine state, 3 a–d form thermotropic hexagonal columnar mesophases which exist over a broad temperature range from below −30 °C to over 300 °C. For the tetraphenoxy-substituted compound 3 e, however, a layered crystalline structure was found. This difference in behavior can be explained by the concept of microphase segregation of the aromatic cores of the molecules and the alkyl chains at the periphery. The high stability and bright fluorescence of the mesophase of several of the compounds make them promising for applications as polarizers or components in (opto)electronic devices.
• A Triangle−Square Equilibrium of Metallosupramolecular Assemblies Based on Pd(II) and Pt(II) Corners and Diazadibenzoperylene Bridging Ligands. Sautter, Armin; Schmid, Dietmar G.; Jung, Günther; Würthner, Frank. In J. Am. Chem. Soc., 123(23), pp. 5424–5430. 2001.

  PMID: 11389622
  • [ Abstract ]
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  • [ DOI ]
  Tetraaryloxy-substituted diazadibenzoperylene bridging ligands 1a,b were employed in transition metal-directed self-assembly with Pd(II) and Pt(II) phosphane triflates 2a,b which resulted in complex dynamic equilibria between molecular triangles 3a−d and molecular squares 4a−d in solution. Characterization of the equilibria and assignment of the metallacycles was accomplished by 1H and 31P1H NMR spectroscopy in combination with electrospray ionization Fourier transform ion cyclotron mass spectrometry (ESI-FTICR-MS). It was found that the equilibria depend on several factors, such as the metal ion (Pd2+ or Pt2+), the solvent, and the steric demand of the phenoxy substituents of the diazadibenzoperylene ligands 1a,b. Introduction of bulky tert-butyl groups in 1b shifts the equilibrium significantly in the direction of the molecular squares. Molecular dynamics simulations of the triangle and square structures revealed critical steric effects and restricted conformational flexibilities of the phosphane and diazadibenzoperylene ligands that help explain the distinct dynamic behavior observed in variable-temperature NMR studies. Concentration-dependent UV/vis and fluorescence spectroscopy revealed the limited stability of the assemblies and confirmed the reversible nature of the dynamic equilibria.

  @article{doi:10.1021/ja004360y, abstract = {Tetraaryloxy-substituted diazadibenzoperylene bridging ligands 1a,b were employed in transition metal-directed self-assembly with Pd(II) and Pt(II) phosphane triflates 2a,b which resulted in complex dynamic equilibria between molecular triangles 3a−d and molecular squares 4a−d in solution. Characterization of the equilibria and assignment of the metallacycles was accomplished by 1H and 31P{1H} NMR spectroscopy in combination with electrospray ionization Fourier transform ion cyclotron mass spectrometry (ESI-FTICR-MS). It was found that the equilibria depend on several factors, such as the metal ion (Pd2+ or Pt2+), the solvent, and the steric demand of the phenoxy substituents of the diazadibenzoperylene ligands 1a,b. Introduction of bulky tert-butyl groups in 1b shifts the equilibrium significantly in the direction of the molecular squares. Molecular dynamics simulations of the triangle and square structures revealed critical steric effects and restricted conformational flexibilities of the phosphane and diazadibenzoperylene ligands that help explain the distinct dynamic behavior observed in variable-temperature NMR studies. Concentration-dependent UV/vis and fluorescence spectroscopy revealed the limited stability of the assemblies and confirmed the reversible nature of the dynamic equilibria.}, author = {Sautter, Armin and Schmid, Dietmar G. and Jung, Günther and Würthner, Frank}, journal = {J. Am. Chem. Soc.}, keywords = {myown}, note = {PMID: 11389622}, number = 23, pages = {5424-5430}, title = {A Triangle−Square Equilibrium of Metallosupramolecular Assemblies Based on Pd(II) and Pt(II) Corners and Diazadibenzoperylene Bridging Ligands}, volume = 123, year = 2001 }

  %0 Journal Article %1 doi:10.1021/ja004360y %A Sautter, Armin %A Schmid, Dietmar G. %A Jung, Günther %A Würthner, Frank %D 2001 %J J. Am. Chem. Soc. %N 23 %P 5424-5430 %R 10.1021/ja004360y %T A Triangle−Square Equilibrium of Metallosupramolecular Assemblies Based on Pd(II) and Pt(II) Corners and Diazadibenzoperylene Bridging Ligands %U http://dx.doi.org/10.1021/ja004360y %V 123 %X Tetraaryloxy-substituted diazadibenzoperylene bridging ligands 1a,b were employed in transition metal-directed self-assembly with Pd(II) and Pt(II) phosphane triflates 2a,b which resulted in complex dynamic equilibria between molecular triangles 3a−d and molecular squares 4a−d in solution. Characterization of the equilibria and assignment of the metallacycles was accomplished by 1H and 31P1H NMR spectroscopy in combination with electrospray ionization Fourier transform ion cyclotron mass spectrometry (ESI-FTICR-MS). It was found that the equilibria depend on several factors, such as the metal ion (Pd2+ or Pt2+), the solvent, and the steric demand of the phenoxy substituents of the diazadibenzoperylene ligands 1a,b. Introduction of bulky tert-butyl groups in 1b shifts the equilibrium significantly in the direction of the molecular squares. Molecular dynamics simulations of the triangle and square structures revealed critical steric effects and restricted conformational flexibilities of the phosphane and diazadibenzoperylene ligands that help explain the distinct dynamic behavior observed in variable-temperature NMR studies. Concentration-dependent UV/vis and fluorescence spectroscopy revealed the limited stability of the assemblies and confirmed the reversible nature of the dynamic equilibria.
• Fluorescent and Electroactive Cyclic Assemblies from Perylene Tetracarboxylic Acid Bisimide Ligands and Metal Phosphane Triflates. Würthner, Frank; Sautter, Armin; Schmid, Dietmar; Weber, Peter J. A. In Chemistry – A European Journal, 7(4), pp. 894–902. 2001.
  • [ Abstract ]
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  • [ DOI ]
  Tetraaryloxy-substituted perylene tetracarboxylic acid bisimides with one or two 4-pyridyl receptor substituents at the imide functionality were synthesized and employed in transition metal directed self-assembly with PdII and PtII phosphane triflates. Upon mixing of the components, quantitative formation of functional molecular square-type complexes containing four dye molecules and model complexes of a 2:1 (perylene bisimide ligand:transition metal ion) stoichiometry was observed. The isolated metallosupramolecular squares were characterized by 1H and 31P 1H NMR spectroscopy as well as conventional electrospray ionization (ESI) and ESI-FTICR mass spectrometry, which gave evidence for the structure and the high stability of these giant cyclic dye assemblies (molecular weight (3 a)=8172, Pt−Pt corner diagonal ca. 3.4 nm). Studies of the optical absorption and fluorescence properties and the electrochemistry and spectroelectrochemistry of both the perylene bisimide ligands and the perylene bisimide metal complexes show that PtII coordination does not interfere with the optical and electrochemical properties of the perylene bisimide ligands; this gives squares with high fluorescence quantum yields (ΦF (3 a)=0.88) and three fully reversible redox couples. The latter could be unambiguously related to quantitative formation of perylene bisimide radical cations (E1/2=+0.93 V vs. Fc/Fc+), radical anions (E1/2=−1.01 V vs. Fc/Fc+), and dianions (E1/2=−1.14 V vs. Fc/Fc+); these redox reactions change the charge state of the cyclic assembly from +12 to zero. In contrast, PdII coordination influenced the electrochemical properties of the assembly because of an irreversible palladium reduction at E1/2=−1.15 V versus Fc/Fc+. Finally, dynamic ligand exchange processes between different metallosupramolecular assemblies were investigated by multinuclear NMR and electrospray mass spectrometry. These studies confirmed the reversible nature of the pyridine−PtII/PdII coordination process.

  @article{CHEM:CHEM894, abstract = {Tetraaryloxy-substituted perylene tetracarboxylic acid bisimides with one or two 4-pyridyl receptor substituents at the imide functionality were synthesized and employed in transition metal directed self-assembly with PdII and PtII phosphane triflates. Upon mixing of the components, quantitative formation of functional molecular square-type complexes containing four dye molecules and model complexes of a 2:1 (perylene bisimide ligand:transition metal ion) stoichiometry was observed. The isolated metallosupramolecular squares were characterized by 1H and 31P {1H} NMR spectroscopy as well as conventional electrospray ionization (ESI) and ESI-FTICR mass spectrometry, which gave evidence for the structure and the high stability of these giant cyclic dye assemblies (molecular weight (3 a)=8172, Pt−Pt corner diagonal ca. 3.4 nm). Studies of the optical absorption and fluorescence properties and the electrochemistry and spectroelectrochemistry of both the perylene bisimide ligands and the perylene bisimide metal complexes show that PtII coordination does not interfere with the optical and electrochemical properties of the perylene bisimide ligands; this gives squares with high fluorescence quantum yields (ΦF (3 a)=0.88) and three fully reversible redox couples. The latter could be unambiguously related to quantitative formation of perylene bisimide radical cations (E1/2=+0.93 V vs. Fc/Fc+), radical anions (E1/2=−1.01 V vs. Fc/Fc+), and dianions (E1/2=−1.14 V vs. Fc/Fc+); these redox reactions change the charge state of the cyclic assembly from +12 to zero. In contrast, PdII coordination influenced the electrochemical properties of the assembly because of an irreversible palladium reduction at E1/2=−1.15 V versus Fc/Fc+. Finally, dynamic ligand exchange processes between different metallosupramolecular assemblies were investigated by multinuclear NMR and electrospray mass spectrometry. These studies confirmed the reversible nature of the pyridine−PtII/PdII coordination process.}, author = {Würthner, Frank and Sautter, Armin and Schmid, Dietmar and Weber, Peter J. A.}, journal = {Chemistry – A European Journal}, keywords = {myown}, number = 4, pages = {894–902}, publisher = {WILEY-VCH Verlag GmbH}, title = {Fluorescent and Electroactive Cyclic Assemblies from Perylene Tetracarboxylic Acid Bisimide Ligands and Metal Phosphane Triflates}, volume = 7, year = 2001 }

  %0 Journal Article %1 CHEM:CHEM894 %A Würthner, Frank %A Sautter, Armin %A Schmid, Dietmar %A Weber, Peter J. A. %D 2001 %I WILEY-VCH Verlag GmbH %J Chemistry – A European Journal %N 4 %P 894--902 %R 10.1002/1521-3765(20010216)7:4<894::AID-CHEM894>3.0.CO;2-N %T Fluorescent and Electroactive Cyclic Assemblies from Perylene Tetracarboxylic Acid Bisimide Ligands and Metal Phosphane Triflates %U http://dx.doi.org/10.1002/1521-3765(20010216)7:4<894::AID-CHEM894>3.0.CO;2-N %V 7 %X Tetraaryloxy-substituted perylene tetracarboxylic acid bisimides with one or two 4-pyridyl receptor substituents at the imide functionality were synthesized and employed in transition metal directed self-assembly with PdII and PtII phosphane triflates. Upon mixing of the components, quantitative formation of functional molecular square-type complexes containing four dye molecules and model complexes of a 2:1 (perylene bisimide ligand:transition metal ion) stoichiometry was observed. The isolated metallosupramolecular squares were characterized by 1H and 31P 1H NMR spectroscopy as well as conventional electrospray ionization (ESI) and ESI-FTICR mass spectrometry, which gave evidence for the structure and the high stability of these giant cyclic dye assemblies (molecular weight (3 a)=8172, Pt−Pt corner diagonal ca. 3.4 nm). Studies of the optical absorption and fluorescence properties and the electrochemistry and spectroelectrochemistry of both the perylene bisimide ligands and the perylene bisimide metal complexes show that PtII coordination does not interfere with the optical and electrochemical properties of the perylene bisimide ligands; this gives squares with high fluorescence quantum yields (ΦF (3 a)=0.88) and three fully reversible redox couples. The latter could be unambiguously related to quantitative formation of perylene bisimide radical cations (E1/2=+0.93 V vs. Fc/Fc+), radical anions (E1/2=−1.01 V vs. Fc/Fc+), and dianions (E1/2=−1.14 V vs. Fc/Fc+); these redox reactions change the charge state of the cyclic assembly from +12 to zero. In contrast, PdII coordination influenced the electrochemical properties of the assembly because of an irreversible palladium reduction at E1/2=−1.15 V versus Fc/Fc+. Finally, dynamic ligand exchange processes between different metallosupramolecular assemblies were investigated by multinuclear NMR and electrospray mass spectrometry. These studies confirmed the reversible nature of the pyridine−PtII/PdII coordination process.
• ATOP Dyes. Optimization of a Multifunctional Merocyanine Chromophore for High Refractive Index Modulation in Photorefractive Materials. Würthner, Frank; Yao, Sheng; Schilling, Joachim; Wortmann, Rüdiger; Redi-Abshiro, Mesfin; Mecher, Erwin; Gallego-Gomez, Francisco; Meerholz, Klaus. In J. Am. Chem. Soc., 123(12), pp. 2810–2824. 2001.

  PMID: 11456967
  • [ Abstract ]
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  This paper reports synthesis, characterization and structural optimization of amino-thienyl-dioxocyano-pyridine (ATOP) chromophores toward a multifunctional amorphous material with unprecedented photorefractive performance. The structural (dynamic NMR, XRD) and electronic (UV/vis, electrooptical absorption, Kerr effect measurements) characterization of the ATOP chromophore revealed a cyanine-type π-conjugated system with an intense and narrow absorption band (εmax = 140 000 L mol-1 cm-1), high polarizability anisotropy (δα0 = 55 × 10-40 C V-1 m2), and a large dipole moment (13 D). This combination of molecular electronic properties is a prerequisite for strong electrooptical response in photorefractive materials with low glass-transition temperature (Tg). Other important materials-related properties such as compatibility with the photoconducting poly(N-vinylcarbazole) (PVK) host matrix, low melting point, low Tg, and film-forming capabilities were optimized by variation of four different alkyl substituents attached to the ATOP core. A morphologically stable PVK-based composite containing 40 wt \% of ATOP-3 showed an excellent photorefractive response characterized by a refractive index modulation of Δn ≈ 0.007 and a gain coefficient of Γ ≈ 180 cm-1 at a moderate electrical field strength of E = 35 V μm-1. Even larger effects were observed with thin amorphous films consisting of the pure glass-forming dye ATOP-4 (Tg = 16 °C) and 1 wt \% of the photosensitizer 2,4,7-trinitro-9-fluorenylidene-malononitrile (TNFM). This material showed complete internal diffraction at a field strength of only E = 10 V μm-1 and Δn reached 0.01 at only E = 22 V μm-1 without addition of any specific photoconductor.

  @article{doi:10.1021/ja002321g, abstract = {This paper reports synthesis, characterization and structural optimization of amino-thienyl-dioxocyano-pyridine (ATOP) chromophores toward a multifunctional amorphous material with unprecedented photorefractive performance. The structural (dynamic NMR, XRD) and electronic (UV/vis, electrooptical absorption, Kerr effect measurements) characterization of the ATOP chromophore revealed a cyanine-type π-conjugated system with an intense and narrow absorption band (εmax = 140 000 L mol-1 cm-1), high polarizability anisotropy (δα0 = 55 × 10-40 C V-1 m2), and a large dipole moment (13 D). This combination of molecular electronic properties is a prerequisite for strong electrooptical response in photorefractive materials with low glass-transition temperature (Tg). Other important materials-related properties such as compatibility with the photoconducting poly(N-vinylcarbazole) (PVK) host matrix, low melting point, low Tg, and film-forming capabilities were optimized by variation of four different alkyl substituents attached to the ATOP core. A morphologically stable PVK-based composite containing 40 wt \% of ATOP-3 showed an excellent photorefractive response characterized by a refractive index modulation of Δn ≈ 0.007 and a gain coefficient of Γ ≈ 180 cm-1 at a moderate electrical field strength of E = 35 V μm-1. Even larger effects were observed with thin amorphous films consisting of the pure glass-forming dye ATOP-4 (Tg = 16 °C) and 1 wt \% of the photosensitizer 2,4,7-trinitro-9-fluorenylidene-malononitrile (TNFM). This material showed complete internal diffraction at a field strength of only E = 10 V μm-1 and Δn reached 0.01 at only E = 22 V μm-1 without addition of any specific photoconductor.}, author = {Würthner, Frank and Yao, Sheng and Schilling, Joachim and Wortmann, Rüdiger and Redi-Abshiro, Mesfin and Mecher, Erwin and Gallego-Gomez, Francisco and Meerholz, Klaus}, journal = {J. Am. Chem. Soc.}, keywords = {myown}, note = {PMID: 11456967}, number = 12, pages = {2810-2824}, title = {ATOP Dyes. Optimization of a Multifunctional Merocyanine Chromophore for High Refractive Index Modulation in Photorefractive Materials}, volume = 123, year = 2001 }

  %0 Journal Article %1 doi:10.1021/ja002321g %A Würthner, Frank %A Yao, Sheng %A Schilling, Joachim %A Wortmann, Rüdiger %A Redi-Abshiro, Mesfin %A Mecher, Erwin %A Gallego-Gomez, Francisco %A Meerholz, Klaus %D 2001 %J J. Am. Chem. Soc. %N 12 %P 2810-2824 %R 10.1021/ja002321g %T ATOP Dyes. Optimization of a Multifunctional Merocyanine Chromophore for High Refractive Index Modulation in Photorefractive Materials %U http://dx.doi.org/10.1021/ja002321g %V 123 %X This paper reports synthesis, characterization and structural optimization of amino-thienyl-dioxocyano-pyridine (ATOP) chromophores toward a multifunctional amorphous material with unprecedented photorefractive performance. The structural (dynamic NMR, XRD) and electronic (UV/vis, electrooptical absorption, Kerr effect measurements) characterization of the ATOP chromophore revealed a cyanine-type π-conjugated system with an intense and narrow absorption band (εmax = 140 000 L mol-1 cm-1), high polarizability anisotropy (δα0 = 55 × 10-40 C V-1 m2), and a large dipole moment (13 D). This combination of molecular electronic properties is a prerequisite for strong electrooptical response in photorefractive materials with low glass-transition temperature (Tg). Other important materials-related properties such as compatibility with the photoconducting poly(N-vinylcarbazole) (PVK) host matrix, low melting point, low Tg, and film-forming capabilities were optimized by variation of four different alkyl substituents attached to the ATOP core. A morphologically stable PVK-based composite containing 40 wt \% of ATOP-3 showed an excellent photorefractive response characterized by a refractive index modulation of Δn ≈ 0.007 and a gain coefficient of Γ ≈ 180 cm-1 at a moderate electrical field strength of E = 35 V μm-1. Even larger effects were observed with thin amorphous films consisting of the pure glass-forming dye ATOP-4 (Tg = 16 °C) and 1 wt \% of the photosensitizer 2,4,7-trinitro-9-fluorenylidene-malononitrile (TNFM). This material showed complete internal diffraction at a field strength of only E = 10 V μm-1 and Δn reached 0.01 at only E = 22 V μm-1 without addition of any specific photoconductor.
• Farbstofforganisate: Biomimetik und funktionelle Materialien. Würthner, Frank. In Nachrichten aus der Chemie, (49), pp. 1284–1290. 2001.
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  @article{noauthororeditor2001, author = {Würthner, Frank}, journal = {Nachrichten aus der Chemie}, keywords = {myown}, number = 49, pages = {1284–1290}, title = {Farbstofforganisate: Biomimetik und funktionelle Materialien.}, year = 2001 }

  %0 Journal Article %1 noauthororeditor2001 %A Würthner, Frank %D 2001 %J Nachrichten aus der Chemie %N 49 %P 1284–1290 %T Farbstofforganisate: Biomimetik und funktionelle Materialien.
• Hydrogen bond directed formation of liquid-crystalline merocyanine dye assemblies. Würthner, Frank; Yao, Sheng; Heise, Bernd; Tschierske, Carsten. In Chem. Commun., (21), pp. 2260–2261. 2001.
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  Combined interaction of triple hydrogen bonding, dipolar [small pi]-[small pi] aggregation and micro-segregation in a melamine-barbituric acid dye assembly leads to a columnar mesophase which could be characterized by optical polarising microscopy, differential scanning calorimetry and X-ray diffraction.

  @article{B106413D, abstract = {Combined interaction of triple hydrogen bonding{,} dipolar [small pi]-[small pi] aggregation and micro-segregation in a melamine-barbituric acid dye assembly leads to a columnar mesophase which could be characterized by optical polarising microscopy{,} differential scanning calorimetry and X-ray diffraction.}, author = {Würthner, Frank and Yao, Sheng and Heise, Bernd and Tschierske, Carsten}, journal = {Chem. Commun.}, keywords = {myown}, number = 21, pages = {2260-2261}, publisher = {The Royal Society of Chemistry}, title = {Hydrogen bond directed formation of liquid-crystalline merocyanine dye assemblies}, year = 2001 }

  %0 Journal Article %1 B106413D %A Würthner, Frank %A Yao, Sheng %A Heise, Bernd %A Tschierske, Carsten %D 2001 %I The Royal Society of Chemistry %J Chem. Commun. %N 21 %P 2260-2261 %R 10.1039/B106413D %T Hydrogen bond directed formation of liquid-crystalline merocyanine dye assemblies %U http://dx.doi.org/10.1039/B106413D %X Combined interaction of triple hydrogen bonding, dipolar [small pi]-[small pi] aggregation and micro-segregation in a melamine-barbituric acid dye assembly leads to a columnar mesophase which could be characterized by optical polarising microscopy, differential scanning calorimetry and X-ray diffraction.

• Hierarchical Self-Organization of Perylene Bisimide-Melamine Assemblies to Fluorescent Mesoscopic Superstructures. Würthner, Frank; Thalacker, C.; Sautter, A.; Schärtl, W.; Ibach, W.; Hollricher, O. In Chem. Eur. J., (6), pp. 3871–3886 (Titelbild). 2000.
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  @article{wurthner2000hierarchical, author = {Würthner, Frank and Thalacker, C. and Sautter, A. and Schärtl, W. and Ibach, W. and Hollricher, O.}, journal = {Chem. Eur. J.}, keywords = {myown}, number = 6, pages = {3871–3886 (Titelbild)}, title = {Hierarchical Self-Organization of Perylene Bisimide-Melamine Assemblies to Fluorescent Mesoscopic Superstructures.}, year = 2000 }

  %0 Journal Article %1 wurthner2000hierarchical %A Würthner, Frank %A Thalacker, C. %A Sautter, A. %A Schärtl, W. %A Ibach, W. %A Hollricher, O. %D 2000 %J Chem. Eur. J. %N 6 %P 3871–3886 (Titelbild) %T Hierarchical Self-Organization of Perylene Bisimide-Melamine Assemblies to Fluorescent Mesoscopic Superstructures.
• Optimization of Molecular and Supramolecular Properties of Merocyanine Dyes for Photorefractive Organic Glasses. Würthner, Frank; Yao, S.; Wortmann, R. In Polym. Mater. Sci. Eng., (83), pp. 186–187. 2000.
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  @article{wurthner2000optimization, author = {Würthner, Frank and Yao, S. and Wortmann, R.}, journal = {Polym. Mater. Sci. Eng.}, keywords = {myown}, number = 83, pages = {186–187}, title = {Optimization of Molecular and Supramolecular Properties of Merocyanine Dyes for Photorefractive Organic Glasses.}, year = 2000 }

  %0 Journal Article %1 wurthner2000optimization %A Würthner, Frank %A Yao, S. %A Wortmann, R. %D 2000 %J Polym. Mater. Sci. Eng. %N 83 %P 186–187 %T Optimization of Molecular and Supramolecular Properties of Merocyanine Dyes for Photorefractive Organic Glasses.
• Highly Fluorescent and Electroactive Molecular Squares Containing Perylene Bisimide Ligands. Würthner, Frank; Sautter, A. In Chem. Commun, pp. 445–446. 2000.
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  @article{wurthner2000highly, author = {Würthner, Frank and Sautter, A.}, journal = {Chem. Commun}, keywords = {myown}, pages = {445–446}, title = {Highly Fluorescent and Electroactive Molecular Squares Containing Perylene Bisimide Ligands.}, year = 2000 }

  %0 Journal Article %1 wurthner2000highly %A Würthner, Frank %A Sautter, A. %D 2000 %J Chem. Commun %P 445–446 %T Highly Fluorescent and Electroactive Molecular Squares Containing Perylene Bisimide Ligands.
• Towards Morphologically Stable Photorefractive Composites: A Comparative Study of ATOP/PVK-Based Materials. Mecher, E.; Gallego-Gomez, F.; Bräuchle, C.; Meerholz, K.; Wortmann, R.; Yao, S.; Sautter, A.; Würthner, F. In Proc. SPIE, 4104, pp. 118–129. 2000.
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  @article{mecher2000towards, author = {Mecher, E. and Gallego-Gomez, F. and Bräuchle, C. and Meerholz, K. and Wortmann, R. and Yao, S. and Sautter, A. and Würthner, F.}, journal = {Proc. SPIE}, keywords = {myown}, pages = {118-129}, title = {Towards Morphologically Stable Photorefractive Composites: A Comparative Study of ATOP/PVK-Based Materials.}, volume = 4104, year = 2000 }

  %0 Journal Article %1 mecher2000towards %A Mecher, E. %A Gallego-Gomez, F. %A Bräuchle, C. %A Meerholz, K. %A Wortmann, R. %A Yao, S. %A Sautter, A. %A Würthner, F. %D 2000 %J Proc. SPIE %P 118-129 %T Towards Morphologically Stable Photorefractive Composites: A Comparative Study of ATOP/PVK-Based Materials. %V 4104
• Towards Morphologically Stable Photorefractive Composites: A Comparative Study of ATOP/PVK-Based Materials. Mecher, E.; Gallego-Gomez, F.; Bräuchle, C.; Meerholz, K.; Wortmann, R.; Yao, S.; Sautter, A.; Würthner, F. In Proc. SPIE, 4104, pp. 118–129. 2000.
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  @article{mecher2000towards, author = {Mecher, E. and Gallego-Gomez, F. and Bräuchle, C. and Meerholz, K. and Wortmann, R. and Yao, S. and Sautter, A. and Würthner, F.}, journal = {Proc. SPIE}, keywords = {myown}, pages = {118-129}, title = {Towards Morphologically Stable Photorefractive Composites: A Comparative Study of ATOP/PVK-Based Materials.}, volume = 4104, year = 2000 }

  %0 Journal Article %1 mecher2000towards %A Mecher, E. %A Gallego-Gomez, F. %A Bräuchle, C. %A Meerholz, K. %A Wortmann, R. %A Yao, S. %A Sautter, A. %A Würthner, F. %D 2000 %J Proc. SPIE %P 118-129 %T Towards Morphologically Stable Photorefractive Composites: A Comparative Study of ATOP/PVK-Based Materials. %V 4104
• Substituted Diazadibenzoperylenes: New Functional Building Blocks for Supramolecular Chemistry. Würthner, Frank; Sautter, A.; Thalacker, C. In Int. Ed. Engl., (39), pp. 1243–1245. 2000.
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  @article{wurthner2000substituted, author = {Würthner, Frank and Sautter, A. and Thalacker, C.}, journal = {Int. Ed. Engl.}, keywords = {myown}, number = 39, pages = {1243–1245}, title = {Substituted Diazadibenzoperylenes: New Functional Building Blocks for Supramolecular Chemistry.}, year = 2000 }

  %0 Journal Article %1 wurthner2000substituted %A Würthner, Frank %A Sautter, A. %A Thalacker, C. %D 2000 %J Int. Ed. Engl. %N 39 %P 1243–1245 %T Substituted Diazadibenzoperylenes: New Functional Building Blocks for Supramolecular Chemistry.
• Dipolar Dye Aggregates: a Problem for Nonlinear Optics, but a Chance for Supramolecular Chemistry. Würthner, Frank; Yao, S. In Int. Ed. Engl., (39), pp. 1978–1981. 2000.
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  @article{wurthner2000dipolar, author = {Würthner, Frank and Yao, S.}, journal = {Int. Ed. Engl.}, keywords = {myown}, number = 39, pages = {1978–1981}, title = {Dipolar Dye Aggregates: a Problem for Nonlinear Optics, but a Chance for Supramolecular Chemistry.}, year = 2000 }

  %0 Journal Article %1 wurthner2000dipolar %A Würthner, Frank %A Yao, S. %D 2000 %J Int. Ed. Engl. %N 39 %P 1978–1981 %T Dipolar Dye Aggregates: a Problem for Nonlinear Optics, but a Chance for Supramolecular Chemistry.
• Molecular Design of Thermally Stable Glass-Forming Merocyanine Dyes. Würthner, Frank; Yao, S.; Wortmann, R. In J. Information Recording, pp. 445–446. 2000.
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  @article{wurthner2000molecular, author = {Würthner, Frank and Yao, S. and Wortmann, R.}, journal = {J. Information Recording}, keywords = {myown}, pages = {445–446}, title = {Molecular Design of Thermally Stable Glass-Forming Merocyanine Dyes.}, year = 2000 }

  %0 Journal Article %1 wurthner2000molecular %A Würthner, Frank %A Yao, S. %A Wortmann, R. %D 2000 %J J. Information Recording %P 445–446 %T Molecular Design of Thermally Stable Glass-Forming Merocyanine Dyes.

• Electrooptical Chromophores for Nonlinear Optical and Photorefractive Applications. Beckmann, S.; Etzbach, K.-H.; Krämer, P.; Lukaszuk, K.; Matschiner, R.; Schmidt, A. J.; Schuhmacher, P.; Sens, R.; Seybold, G.; Wortmann, R.; Würthner, Frank. In Adv. Mater., (11), pp. 536–541. 1999.
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  @article{beckmann1999electrooptical, author = {Beckmann, S. and Etzbach, K.-H. and Krämer, P. and Lukaszuk, K. and Matschiner, R. and Schmidt, A. J. and Schuhmacher, P. and Sens, R. and Seybold, G. and Wortmann, R. and Würthner, Frank}, journal = {Adv. Mater.}, keywords = {myown}, number = 11, pages = {536–541}, title = {Electrooptical Chromophores for Nonlinear Optical and Photorefractive Applications.}, year = 1999 }

  %0 Journal Article %1 beckmann1999electrooptical %A Beckmann, S. %A Etzbach, K.-H. %A Krämer, P. %A Lukaszuk, K. %A Matschiner, R. %A Schmidt, A. J. %A Schuhmacher, P. %A Sens, R. %A Seybold, G. %A Wortmann, R. %A Würthner, Frank %D 1999 %J Adv. Mater. %N 11 %P 536–541 %T Electrooptical Chromophores for Nonlinear Optical and Photorefractive Applications.
• Hierarchical Organization of Functional Perylene Chromophores to Mesoscopic Superstructures by Hydrogen Bonding and p-p-Interactions. Würthner, Frank; Thalacker, C.; Sautter, A. In Adv. Mater., (11), pp. 754–758. 1999.
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  @article{wurthner1999hierarchical, author = {Würthner, Frank and Thalacker, C. and Sautter, A.}, journal = {Adv. Mater.}, keywords = {myown}, number = 11, pages = {754–758}, title = {Hierarchical Organization of Functional Perylene Chromophores to Mesoscopic Superstructures by Hydrogen Bonding and p-p-Interactions.}, year = 1999 }

  %0 Journal Article %1 wurthner1999hierarchical %A Würthner, Frank %A Thalacker, C. %A Sautter, A. %D 1999 %J Adv. Mater. %N 11 %P 754–758 %T Hierarchical Organization of Functional Perylene Chromophores to Mesoscopic Superstructures by Hydrogen Bonding and p-p-Interactions.
• Design, Synthesis, and Evaluation of a Dye Library: Glass-Forming and Solid-State Luminescent Merocyanines for Functional Materials. Würthner, Frank; Sens, R.; Etzbach, K.-H.; Seybold, G. In Int. Ed. Engl., (38), pp. 1649–1652. 1999.
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  @article{wurthner1999design, author = {Würthner, Frank and Sens, R. and Etzbach, K.-H. and Seybold, G.}, journal = {Int. Ed. Engl.}, keywords = {myown}, number = 38, pages = {1649–1652}, title = {Design, Synthesis, and Evaluation of a Dye Library: Glass-Forming and Solid-State Luminescent Merocyanines for Functional Materials.}, year = 1999 }

  %0 Journal Article %1 wurthner1999design %A Würthner, Frank %A Sens, R. %A Etzbach, K.-H. %A Seybold, G. %D 1999 %J Int. Ed. Engl. %N 38 %P 1649–1652 %T Design, Synthesis, and Evaluation of a Dye Library: Glass-Forming and Solid-State Luminescent Merocyanines for Functional Materials.
• Improved Alignment of Birefringent ATOP Chromophores for High-Performance Photorefractive Materials. Würthner, Frank; Sautter, A.; Legrand, C.; Mecher, E.; Meerholz, K.; Wortmann, R. In Polym. Mater. Sci. Eng., (80), pp. 252–253. 1999.
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  @article{wurthner1999improved, author = {Würthner, Frank and Sautter, A. and Legrand, C. and Mecher, E. and Meerholz, K. and Wortmann, R.}, journal = {Polym. Mater. Sci. Eng.}, keywords = {myown}, number = 80, pages = {252–253}, title = {Improved Alignment of Birefringent ATOP Chromophores for High-Performance Photorefractive Materials.}, year = 1999 }

  %0 Journal Article %1 wurthner1999improved %A Würthner, Frank %A Sautter, A. %A Legrand, C. %A Mecher, E. %A Meerholz, K. %A Wortmann, R. %D 1999 %J Polym. Mater. Sci. Eng. %N 80 %P 252–253 %T Improved Alignment of Birefringent ATOP Chromophores for High-Performance Photorefractive Materials.
• DMF in Acetic Anhydride: a Useful Reagent for Multiple-Component Syntheses of Merocyanine Dyes. Würthner, F. In Synthesis, pp. 2103–2113. 1999.
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  @article{wurthner1999acetic, author = {Würthner, F.}, journal = {Synthesis}, keywords = {myown}, pages = {2103–2113}, title = {DMF in Acetic Anhydride: a Useful Reagent for Multiple-Component Syntheses of Merocyanine Dyes.}, year = 1999 }

  %0 Journal Article %1 wurthner1999acetic %A Würthner, F. %D 1999 %J Synthesis %P 2103–2113 %T DMF in Acetic Anhydride: a Useful Reagent for Multiple-Component Syntheses of Merocyanine Dyes.

• Improved Index Modulation and Stability of Photorefractive Polymers using Merocyanine Dyes. Meerholz, K.; Bittner, R.; Mecher, E.; DeNardin, Y.; Bräuchle, C.; Wortmann, R.; Würthner, Frank. In Proc. SPIE, 3471, pp. 52–59. 1998.
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  @article{meerholz1998improved, author = {Meerholz, K. and Bittner, R. and Mecher, E. and DeNardin, Y. and Bräuchle, C. and Wortmann, R. and Würthner, Frank}, journal = {Proc. SPIE}, keywords = {myown}, pages = {52–59}, title = {Improved Index Modulation and Stability of Photorefractive Polymers using Merocyanine Dyes.}, volume = 3471, year = 1998 }

  %0 Journal Article %1 meerholz1998improved %A Meerholz, K. %A Bittner, R. %A Mecher, E. %A DeNardin, Y. %A Bräuchle, C. %A Wortmann, R. %A Würthner, Frank %D 1998 %J Proc. SPIE %P 52–59 %T Improved Index Modulation and Stability of Photorefractive Polymers using Merocyanine Dyes. %V 3471
• Improved performance of photorefractive polymers based on merocyanine dyes in a polar matrix. Meerholz, K.; DeNardin, Y.; Bittner, R.; Wortmann, R.; Würthner, Frank. In Appl. Phys. Lett., (73), pp. 4–6. 1998.
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  @article{meerholz1998improved, author = {Meerholz, K. and DeNardin, Y. and Bittner, R. and Wortmann, R. and Würthner, Frank}, journal = {Appl. Phys. Lett.}, keywords = {myown}, number = 73, pages = {4–6}, title = {Improved performance of photorefractive polymers based on merocyanine dyes in a polar matrix.}, year = 1998 }

  %0 Journal Article %1 meerholz1998improved %A Meerholz, K. %A DeNardin, Y. %A Bittner, R. %A Wortmann, R. %A Würthner, Frank %D 1998 %J Appl. Phys. Lett. %N 73 %P 4–6 %T Improved performance of photorefractive polymers based on merocyanine dyes in a polar matrix.
• Anthryloligothienylporphyrins: Energy Transfer and Light-Harvesting Systems. Vollmer, M. S.; Würthner, Frank; Effenberger, F.; Emele, P.; Meyer, D. U.; Stümpfig, T.; Port, H.; Wolf, H. C. In Chem. Eur. J., (4), pp. 260–269, Titelbild. 1998.
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  @article{vollmer1998anthryloligothienylporphyrins, author = {Vollmer, M. S. and Würthner, Frank and Effenberger, F. and Emele, P. and Meyer, D. U. and Stümpfig, T. and Port, H. and Wolf, H. C.}, journal = {Chem. Eur. J.}, keywords = {myown}, number = 4, pages = {260–269, Titelbild}, title = {Anthryloligothienylporphyrins: Energy Transfer and Light-Harvesting Systems}, year = 1998 }

  %0 Journal Article %1 vollmer1998anthryloligothienylporphyrins %A Vollmer, M. S. %A Würthner, Frank %A Effenberger, F. %A Emele, P. %A Meyer, D. U. %A Stümpfig, T. %A Port, H. %A Wolf, H. C. %D 1998 %J Chem. Eur. J. %N 4 %P 260–269, Titelbild %T Anthryloligothienylporphyrins: Energy Transfer and Light-Harvesting Systems
• Optimization of neutrocyanine chromophores based on five-membered heterocycles for photorefractive applications. Würthner, Frank; Thalacker, C.; Matschiner, R.; Lukaszuk, K.; Wortmann, R. In Chem. Commun, pp. 1739–1740. 1998.
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  @article{wurthner1998optimization, author = {Würthner, Frank and Thalacker, C. and Matschiner, R. and Lukaszuk, K. and Wortmann, R.}, journal = {Chem. Commun}, keywords = {myown}, pages = {1739–1740}, title = {Optimization of neutrocyanine chromophores based on five-membered heterocycles for photorefractive applications.}, year = 1998 }

  %0 Journal Article %1 wurthner1998optimization %A Würthner, Frank %A Thalacker, C. %A Matschiner, R. %A Lukaszuk, K. %A Wortmann, R. %D 1998 %J Chem. Commun %P 1739–1740 %T Optimization of neutrocyanine chromophores based on five-membered heterocycles for photorefractive applications.
• Improved Index Modulation and Stability of Photorefractive Polymers using Merocyanine Dyes. Meerholz, K.; Bittner, R.; Mecher, E.; DeNardin, Y.; Bräuchle, C.; Wortmann, R.; Würthner, Frank. In Proc. SPIE, 3471, pp. 52–59. 1998.
  • [ BibTeX ]
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  @article{meerholz1998improved, author = {Meerholz, K. and Bittner, R. and Mecher, E. and DeNardin, Y. and Bräuchle, C. and Wortmann, R. and Würthner, Frank}, journal = {Proc. SPIE}, keywords = {myown}, pages = {52–59}, title = {Improved Index Modulation and Stability of Photorefractive Polymers using Merocyanine Dyes.}, volume = 3471, year = 1998 }

  %0 Journal Article %1 meerholz1998improved %A Meerholz, K. %A Bittner, R. %A Mecher, E. %A DeNardin, Y. %A Bräuchle, C. %A Wortmann, R. %A Würthner, Frank %D 1998 %J Proc. SPIE %P 52–59 %T Improved Index Modulation and Stability of Photorefractive Polymers using Merocyanine Dyes. %V 3471
• Highly birefringent neutrocyanine dyes for photorefractive polymers. Wortmann, R.; Würthner, Frank; Sautter, A.; Lukaszuk, K.; Matschiner, R.; Meerholz, K. In Proc. SPIE, 3471, pp. 41–49. 1998.
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  @article{wortmann1998highly, author = {Wortmann, R. and Würthner, Frank and Sautter, A. and Lukaszuk, K. and Matschiner, R. and Meerholz, K.}, journal = {Proc. SPIE}, keywords = {myown}, pages = {41–49}, title = {Highly birefringent neutrocyanine dyes for photorefractive polymers.}, volume = 3471, year = 1998 }

  %0 Journal Article %1 wortmann1998highly %A Wortmann, R. %A Würthner, Frank %A Sautter, A. %A Lukaszuk, K. %A Matschiner, R. %A Meerholz, K. %D 1998 %J Proc. SPIE %P 41–49 %T Highly birefringent neutrocyanine dyes for photorefractive polymers. %V 3471

• Merocyanine Dyes in the Cyanine Limit: a New Class of Chromophores for Photorefractive Materials. Würthner, Frank; Wortmann, R.; Matschiner, R.; Lukaszuk, K.; Meerholz, K.; DeNardin, Y.; Bittner, R.; Bräuchle, C.; Sens, R. In Angew. Chem. Int. Ed., (36), pp. 2865–2768. 1997.
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  @article{wurthner1997merocyanine, author = {Würthner, Frank and Wortmann, R. and Matschiner, R. and Lukaszuk, K. and Meerholz, K. and DeNardin, Y. and Bittner, R. and Bräuchle, C. and Sens, R.}, journal = {Angew. Chem. Int. Ed.}, keywords = {myown}, number = 36, pages = {2865–2768}, title = {Merocyanine Dyes in the Cyanine Limit: a New Class of Chromophores for Photorefractive Materials.}, year = 1997 }

  %0 Journal Article %1 wurthner1997merocyanine %A Würthner, Frank %A Wortmann, R. %A Matschiner, R. %A Lukaszuk, K. %A Meerholz, K. %A DeNardin, Y. %A Bittner, R. %A Bräuchle, C. %A Sens, R. %D 1997 %J Angew. Chem. Int. Ed. %N 36 %P 2865–2768 %T Merocyanine Dyes in the Cyanine Limit: a New Class of Chromophores for Photorefractive Materials.

• Light‐Switchable Catalysis in Synthetic Receptors. Würthner, Frank; Rebek, J. Jr. In Angew. Chem. Int. Ed., 34(4), pp. 446–448. 1995.
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  Catalysis by flicking a “light switch” is possible with an azobenzene‐based template. When the E isomer of the template is irradiated with light of wavelength 366 nm, the isomeric composition is shifted in favor of the catalytically active Z isomer, and the reaction rate for amide bond formation between modified adenine units is increased by a factor of 10. The light‐induced activation of the template is depicted schematically on the right.

  @article{wurthner1995photoschaltbare, abstract = {Catalysis by flicking a “light switch” is possible with an azobenzene‐based template. When the E isomer of the template is irradiated with light of wavelength 366 nm, the isomeric composition is shifted in favor of the catalytically active Z isomer, and the reaction rate for amide bond formation between modified adenine units is increased by a factor of 10. The light‐induced activation of the template is depicted schematically on the right.}, author = {Würthner, Frank and Rebek, J. Jr.}, journal = {Angew. Chem. Int. Ed.}, keywords = {myown}, number = 4, pages = {446 - 448}, title = {Light‐Switchable Catalysis in Synthetic Receptors}, volume = 34, year = 1995 }

  %0 Journal Article %1 wurthner1995photoschaltbare %A Würthner, Frank %A Rebek, J. Jr. %D 1995 %J Angew. Chem. Int. Ed. %N 4 %P 446 - 448 %R 10.1002/anie.199504461 %T Light‐Switchable Catalysis in Synthetic Receptors %U https://onlinelibrary.wiley.com/doi/10.1002/anie.199504461 %V 34 %X Catalysis by flicking a “light switch” is possible with an azobenzene‐based template. When the E isomer of the template is irradiated with light of wavelength 366 nm, the isomeric composition is shifted in favor of the catalytically active Z isomer, and the reaction rate for amide bond formation between modified adenine units is increased by a factor of 10. The light‐induced activation of the template is depicted schematically on the right.
• Photoresponsive Synthetic Receptors: Binding Properties and Photocontrol of Catalytic Activity. Würthner, Frank; Rebek, J. Jr. In J. Chem. Soc. Perkin Trans. 2, pp. 1727–1734. 1995.
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  @article{wurthner1995photoresponsive, author = {Würthner, Frank and Rebek, J. Jr.}, journal = {J. Chem. Soc. Perkin Trans. 2}, keywords = {myown}, pages = {1727–1734}, title = {Photoresponsive Synthetic Receptors: Binding Properties and Photocontrol of Catalytic Activity.}, year = 1995 }

  %0 Journal Article %1 wurthner1995photoresponsive %A Würthner, Frank %A Rebek, J. Jr. %D 1995 %J J. Chem. Soc. Perkin Trans. 2 %P 1727–1734 %T Photoresponsive Synthetic Receptors: Binding Properties and Photocontrol of Catalytic Activity.
• Synthesis and energy transfer properties of terminally substituted oligothiophenes. Würthner, Frank; Vollmer, M. S.; Effenberger, F.; Emele, P.; Meyer, D. U.; Port, H.; Wolf, H. C. In J. Am. Chem. Soc., (117), pp. 8090–8099. 1995.
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  @article{wurthner1995synthesis, author = {Würthner, Frank and Vollmer, M. S. and Effenberger, F. and Emele, P. and Meyer, D. U. and Port, H. and Wolf, H. C.}, journal = {J. Am. Chem. Soc.}, keywords = {myown}, number = 117, pages = {8090–8099}, title = {Synthesis and energy transfer properties of terminally substituted oligothiophenes.}, year = 1995 }

  %0 Journal Article %1 wurthner1995synthesis %A Würthner, Frank %A Vollmer, M. S. %A Effenberger, F. %A Emele, P. %A Meyer, D. U. %A Port, H. %A Wolf, H. C. %D 1995 %J J. Am. Chem. Soc. %N 117 %P 8090–8099 %T Synthesis and energy transfer properties of terminally substituted oligothiophenes.
• Synthesis and solvatochromic properties of donor-acceptor-substituted oligothiophenes. Effenberger, F.; Würthner, Frank; Steybe, F. In J. Org. Chem., (60), pp. 2082–2091. 1995.
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  @article{effenberger1995synthesis, author = {Effenberger, F. and Würthner, Frank and Steybe, F.}, journal = {J. Org. Chem.}, keywords = {myown}, number = 60, pages = {2082–2091}, title = {Synthesis and solvatochromic properties of donor-acceptor-substituted oligothiophenes.}, year = 1995 }

  %0 Journal Article %1 effenberger1995synthesis %A Effenberger, F. %A Würthner, Frank %A Steybe, F. %D 1995 %J J. Org. Chem. %N 60 %P 2082–2091 %T Synthesis and solvatochromic properties of donor-acceptor-substituted oligothiophenes.

• Dual fluorescence of 9-anthryl-substituted oligothiophenes in nonpolar environment. Emele, P.; Meyer, D. U.; Holl, N.; Port, H.; Wolf, H. C.; Würthner, Frank; Bäuerle, P.; Effenberger, F. In Chem. Phys., (181), pp. 417–424. 1994.
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  @article{emele1994fluorescence, author = {Emele, P. and Meyer, D. U. and Holl, N. and Port, H. and Wolf, H. C. and Würthner, Frank and Bäuerle, P. and Effenberger, F.}, journal = {Chem. Phys.}, keywords = {myown}, number = 181, pages = {417–424}, title = {Dual fluorescence of 9-anthryl-substituted oligothiophenes in nonpolar environment.}, year = 1994 }

  %0 Journal Article %1 emele1994fluorescence %A Emele, P. %A Meyer, D. U. %A Holl, N. %A Port, H. %A Wolf, H. C. %A Würthner, Frank %A Bäuerle, P. %A Effenberger, F. %D 1994 %J Chem. Phys. %N 181 %P 417–424 %T Dual fluorescence of 9-anthryl-substituted oligothiophenes in nonpolar environment.

• Selective synthesis of a -substituted oligothiophenes. Bäuerle, P.; Würthner, Frank; Götz, G.; Effenberger, F. In Synthesis, pp. 1099–1103. 1993.
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  @article{bauerle1993selective, author = {Bäuerle, P. and Würthner, Frank and Götz, G. and Effenberger, F.}, journal = {Synthesis}, keywords = {myown}, pages = {1099–1103}, title = {Selective synthesis of a -substituted oligothiophenes.}, year = 1993 }

  %0 Journal Article %1 bauerle1993selective %A Bäuerle, P. %A Würthner, Frank %A Götz, G. %A Effenberger, F. %D 1993 %J Synthesis %P 1099–1103 %T Selective synthesis of a -substituted oligothiophenes.
• Second-order polarizability of donor-acceptor-substituted oligothiophenes: Substituent variation and conjugation length dependence. Würthner, Frank; Effenberger, F.; Wortmann, R.; Krämer, P. In Chem. Phys., (173), pp. 305–314. 1993.
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  @article{wurthner1993secondorder, author = {Würthner, Frank and Effenberger, F. and Wortmann, R. and Krämer, P.}, journal = {Chem. Phys.}, keywords = {myown}, number = 173, pages = {305–314}, title = {Second-order polarizability of donor-acceptor-substituted oligothiophenes: Substituent variation and conjugation length dependence.}, year = 1993 }

  %0 Journal Article %1 wurthner1993secondorder %A Würthner, Frank %A Effenberger, F. %A Wortmann, R. %A Krämer, P. %D 1993 %J Chem. Phys. %N 173 %P 305–314 %T Second-order polarizability of donor-acceptor-substituted oligothiophenes: Substituent variation and conjugation length dependence.
• Synthesis and structural characterization of alkyloligothiophenes - The first isomerically pure dialkylsexithiophene. Bäuerle, P.; Pfau, F.; Schlupp, H.; Würthner, Frank; Gaudl, K. U.; Balpardo Caro, M.; Fischer, P. In J. Chem. Soc. Perkin Trans. 2, pp. 489–494. 1993.
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  @article{bauerle1993synthesis, author = {Bäuerle, P. and Pfau, F. and Schlupp, H. and Würthner, Frank and Gaudl, K. U. and Balpardo Caro, M. and Fischer, P.}, journal = {J. Chem. Soc. Perkin Trans. 2}, keywords = {myown}, pages = {489–494}, title = {Synthesis and structural characterization of alkyloligothiophenes - The first isomerically pure dialkylsexithiophene}, year = 1993 }

  %0 Journal Article %1 bauerle1993synthesis %A Bäuerle, P. %A Pfau, F. %A Schlupp, H. %A Würthner, Frank %A Gaudl, K. U. %A Balpardo Caro, M. %A Fischer, P. %D 1993 %J J. Chem. Soc. Perkin Trans. 2 %P 489–494 %T Synthesis and structural characterization of alkyloligothiophenes - The first isomerically pure dialkylsexithiophene
• 5‐Dimethylamino‐5′‐nitro‐2, 2′‐bithiophene—a New Dye with Pronounced Positive Solvatochromism. Würthner, Frank; Effenberger, F. In Angew. Chem. Int. Ed., 32(5), pp. 719–721. 1993.
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  @article{wurthner19935dimethylamino5nitro22bithiophen, author = {Würthner, Frank and Effenberger, F.}, journal = {Angew. Chem. Int. Ed.}, keywords = {myown}, number = 5, pages = {719 - 721}, title = {5‐Dimethylamino‐5′‐nitro‐2, 2′‐bithiophene—a New Dye with Pronounced Positive Solvatochromism}, volume = 32, year = 1993 }

  %0 Journal Article %1 wurthner19935dimethylamino5nitro22bithiophen %A Würthner, Frank %A Effenberger, F. %D 1993 %J Angew. Chem. Int. Ed. %N 5 %P 719 - 721 %R 10.1002/anie.199307191 %T 5‐Dimethylamino‐5′‐nitro‐2, 2′‐bithiophene—a New Dye with Pronounced Positive Solvatochromism %U https://onlinelibrary.wiley.com/doi/10.1002/anie.199307191 %V 32

• Synthesis and properties of carboxy-functionalized poly-(3-alkylthienylenes). Bäuerle, P.; Gaudl, K. U.; Würthner, Frank; Sariciftci, N. S.; Neugebauer, H.; Mehring, M.; Zhong, C.; Doblhofer, K. In Adv. Mater., 2, pp. 491–494. 1990.
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  @article{bauerle1990synthesis, author = {Bäuerle, P. and Gaudl, K. U. and Würthner, Frank and Sariciftci, N. S. and Neugebauer, H. and Mehring, M. and Zhong, C. and Doblhofer, K.}, journal = {Adv. Mater.}, keywords = {myown}, pages = {491–494}, title = {Synthesis and properties of carboxy-functionalized poly-(3-alkylthienylenes).}, volume = 2, year = 1990 }

  %0 Journal Article %1 bauerle1990synthesis %A Bäuerle, P. %A Gaudl, K. U. %A Würthner, Frank %A Sariciftci, N. S. %A Neugebauer, H. %A Mehring, M. %A Zhong, C. %A Doblhofer, K. %D 1990 %J Adv. Mater. %P 491–494 %T Synthesis and properties of carboxy-functionalized poly-(3-alkylthienylenes). %V 2
• Facile Synthesis of 3‐(ω‐Haloalkyl)thiophenes as Key Building Blocks for Functionalized Thiophenes and Polythiophenes. Bäuerle, P.; Würthner, Frank; Heid, S. In Angew. Chem. Int. Ed., 29(4), pp. 419–420. 1990.
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  @article{bauerle1990einfache, author = {Bäuerle, P. and Würthner, Frank and Heid, S.}, journal = {Angew. Chem. Int. Ed.}, keywords = {myown}, number = 4, pages = {419 - 420}, title = {Facile Synthesis of 3‐(ω‐Haloalkyl)thiophenes as Key Building Blocks for Functionalized Thiophenes and Polythiophenes}, volume = 29, year = 1990 }

  %0 Journal Article %1 bauerle1990einfache %A Bäuerle, P. %A Würthner, Frank %A Heid, S. %D 1990 %J Angew. Chem. Int. Ed. %N 4 %P 419 - 420 %R 10.1002/anie.199004191 %T Facile Synthesis of 3‐(ω‐Haloalkyl)thiophenes as Key Building Blocks for Functionalized Thiophenes and Polythiophenes %U https://onlinelibrary.wiley.com/doi/10.1002/anie.199004191 %V 29