@article{PratiharGhoshStepanenkoetal.2010, author = {Pratihar, Pampa and Ghosh, Suhrit and Stepanenko, Vladimir and Patwardhan, Sameer and Grozema, Ferdinand C. and Siebbeles, Laurens D. A. and W{\"u}rthner, Frank}, title = {Self-assembly and semiconductivity of an oligothiophene supergelator}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-67817}, year = {2010}, abstract = {A bis(trialkoxybenzamide)-functionalized quaterthiophene derivative was synthesized and its self-assembly properties in solution were studied. In non-polar solvents such as cyclohexane, this quaterthiophene π-system formed fibril aggregates with an H-type molecular arrangement due to synergistic effect of hydrogen bonding and π-stacking. The self-assembled fibres were found to gelate numerous organic solvents of diverse polarity. The charge transport ability of such elongated fibres of quaterthiophene π-system was explored by the pulse radiolysis time resolved microwave conductivity (PR-TRMC) technique and moderate mobility values were obtained. Furthermore, initial AFM and UV-vis spectroscopic studies of a mixture of our electron-rich quaterthiophene derivative with the electron acceptor [6,6]-phenyl-C61-butyric acid methyl ester (PCBM) revealed a nanoscale segregated assembly of the individual building blocks in the blend.}, subject = {Organische Chemie}, language = {en} } @article{WolterAizezersFenneletal.2012, author = {Wolter, Steffen and Aizezers, Janis and Fennel, Franziska and Seidel, Marcus and W{\"u}rthner, Frank and K{\"u}hn, Oliver and Lochbrunner, Stefan}, title = {Size-dependent exciton dynamics in one-dimensional perylene bisimide aggregates}, series = {New Journal of Physics}, volume = {14}, journal = {New Journal of Physics}, number = {105027}, doi = {10.1088/1367-2630/14/10/105027}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-135190}, year = {2012}, 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 degrees 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.}, language = {en} } @article{HeStolteBurschkaetal.2015, author = {He, Tao and Stolte, Matthias and Burschka, Christian and Hansen, Nis Hauke and Musiol, Thomas and K{\"a}lblein, Daniel and Pflaum, Jens and Tao, Xutang and Brill, Jochen and W{\"u}rthner, Frank}, title = {Single-crystal field-effect transistors of new Cl\(_{2}\)-NDI polymorph processed by sublimation in air}, series = {Nature Communications}, volume = {6}, journal = {Nature Communications}, number = {5954}, doi = {10.1038/ncomms6954}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-149255}, year = {2015}, abstract = {Physical properties of active materials built up from small molecules are dictated by their molecular packing in the solid state. Here we demonstrate for the first time the growth of n-channel single-crystal field-effect transistors and organic thin-film transistors by sublimation of 2,6-dichloro-naphthalene diimide in air. Under these conditions, a new polymorph with two-dimensional brick-wall packing mode (\(\beta\)-phase) is obtained that is distinguished from the previously reported herringbone packing motif obtained from solution (\(\alpha\)-phase). We are able to fabricate single-crystal field-effect transistors with electron mobilities in air of up to 8.6 cm\(^{2}\)V\(^{-1}\)s\(^{-1}\) (\(\alpha\)-phase) and up to 3.5 cm\(^{2}\)V\(^{-1}\)s\(^{-1}\) (\(\beta\)-phase) on n-octadecyltriethoxysilane-modified substrates. On silicon dioxide, thin-film devices based on \(\beta\)-phase can be manufactured in air giving rise to electron mobilities of 0.37 cm\(^{2}\)V\(^{-1}\)s\(^{-1}\). The simple crystal and thin-film growth procedures by sublimation under ambient conditions avoid elaborate substrate modifications and costly vacuum equipment-based fabrication steps.}, language = {en} } @article{SungKimFimmeletal.2015, author = {Sung, Jooyoung and Kim, Pyosang and Fimmel, Benjamin and W{\"u}rthner, Frank and Kim, Dongho}, title = {Direct observation of ultrafast coherent exciton dynamics in helical π-stacks of self-assembled perylene bisimides}, series = {Nature Communications}, volume = {6}, journal = {Nature Communications}, number = {8646}, doi = {10.1038/ncomms9646}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-148157}, year = {2015}, 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 pi-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.}, language = {en} } @article{GoerlZhangStepanenkoetal.2015, author = {G{\"o}rl, Daniel and Zhang, Xin and Stepanenko, Vladimir and W{\"u}rthner, Frank}, title = {Supramolecular block copolymers by kinetically controlled co-self-assembly of planar and core-twisted perylene bisimides}, series = {Nature Communications}, volume = {6}, journal = {Nature Communications}, number = {7009}, doi = {10.1038/ncomms8009}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-148657}, year = {2015}, 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 (A\(_{m}\)BB)\(_{n}\). 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.}, language = {en} } @article{SpenstYoungWasielewskietal.2016, author = {Spenst, Peter and Young, Ryan M. and Wasielewski, Michael R. and W{\"u}rthner, Frank}, title = {Guest and solvent modulated photo-driven charge separation and triplet generation in a perylene bisimide cyclophane}, series = {Chemical Science}, volume = {7}, journal = {Chemical Science}, number = {8}, doi = {10.1039/c6sc01574c}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-191252}, pages = {5428-5434}, year = {2016}, abstract = {Cofacial positioning of two perylene bisimide (PBI) chromophores at a distance of 6.5 angstrom in a cyclophane structure prohibits the otherwise common excimer formation and directs photoexcited singlet state relaxation towards intramolecular symmetry-breaking charge separation (τ\(_{CS}\) = 161 +/- 4 ps) in polar CH\(_2\)Cl\(_2\), which is thermodynamically favored with a Gibbs free energy of ΔG\(_{CS}\) = -0.32 eV. The charges then recombine slowly in τ\(_{CR}\) = 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 CH\(_2\)Cl\(_2\). 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.}, language = {en} } @article{PloetzPolyutovIvanovetal.2016, author = {Pl{\"o}tz, 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 W{\"u}rthner, Frank and K{\"u}hn, O.}, title = {Biphasic aggregation of a perylene bisimide dye identified by exciton-vibrational spectra}, series = {Physical Chemistry Chemical Physics}, volume = {18}, journal = {Physical Chemistry Chemical Physics}, number = {36}, doi = {10.1039/c6cp04898f}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-187387}, pages = {25110-25119}, year = {2016}, 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.}, language = {en} } @article{GershbergFennelRehmetal.2016, author = {Gershberg, Jana and Fennel, Franziska and Rehm, Thomas H. and Lochbrunner, Stefan and W{\"u}rthner, Frank}, title = {Anti-cooperative supramolecular polymerization: a new K\(_2\)-K model applied to the self-assembly of perylene bisimide dye proceeding via well-defined hydrogen-bonded dimers}, series = {Chemical Science}, volume = {7}, journal = {Chemical Science}, number = {3}, doi = {10.1039/c5sc03759j}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-191428}, pages = {1729-1737}, year = {2016}, 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 π-π-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 K\(_2\)-K model, and thus a new K\(_2\)-K aggregation model has been developed, which interpretes the present anti-cooperative supramolecular polymerization more appropriately. The newly developed K\(_2\)-K model will be useful to describe self-assembly processes of a plethora of other π-conjugated molecules that are characterized by a favored dimer species.}, language = {en} } @article{GoerlSoberatsHerbstetal.2016, author = {G{\"o}rl, Daniel and Soberats, Bartolome and Herbst, Stefanie and Stepanenko, Vladimir and W{\"u}rthner, Frank}, title = {Perylene bisimide hydrogels and lyotropic liquid crystals with temperature-responsive color change}, series = {Chemical Science}, volume = {7}, journal = {Chemical Science}, number = {11}, doi = {10.1039/c6sc02249a}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-162459}, pages = {6786-6790}, year = {2016}, 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 °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.}, language = {en} } @article{BialasZitzlerKunkelKirchneretal.2016, author = {Bialas, David and Zitzler-Kunkel, Andr{\´e} and Kirchner, Eva and Schmidt, David and W{\"u}rthner, Frank}, title = {Structural and quantum chemical analysis of exciton coupling in homo- and heteroaggregate stacks of merocyanines}, series = {Nature Communications}, volume = {7}, journal = {Nature Communications}, doi = {10.1038/ncomms12949}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-170200}, year = {2016}, 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.}, language = {en} } @article{SeifertShoyamaSchmidtetal.2016, author = {Seifert, Sabine and Shoyama, Kazutaka and Schmidt, David and W{\"u}rthner, Frank}, title = {An electron-poor C\(_{64}\) nanographene by palladium-catalyzed cascade C-C bond formation: one-pot synthesis and single-crystal structure analysis}, series = {Angewandte Chemie-International Edition}, volume = {55}, journal = {Angewandte Chemie-International Edition}, number = {22}, doi = {10.1002/anie.201601433}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-188889}, pages = {6390-6395}, year = {2016}, 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 pi-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 C\(_{64}\) 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.}, language = {en} } @article{GrandeSoberatsHerbstetal.2018, author = {Grande, Vincenzo and Soberats, Bartolome and Herbst, Stefanie and Stepanenko, Vladimir and W{\"u}rthner, Frank}, title = {Hydrogen-bonded perylene bisimide J-aggregate aqua material}, volume = {9}, issn = {2041-6539}, doi = {10.1039/C8SC02409J}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-204715}, pages = {6904-6911}, year = {2018}, 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-defined 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.}, language = {en} } @article{HocheSchulzDietrichetal.2019, author = {Hoche, Joscha and Schulz, Alexander and Dietrich, Lysanne Monika and Humeniuk, Alexander and Stolte, Matthias and Schmidt, David and Brixner, Tobias and W{\"u}rthner, Frank and Mitric, Roland}, title = {The origin of the solvent dependence of fluorescence quantum yields in dipolar merocyanine dyes}, series = {Chemical Science}, volume = {10}, journal = {Chemical Science}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-198707}, pages = {11013}, year = {2019}, 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.}, language = {en} } @unpublished{StennettBissingerGriesbecketal.2019, author = {Stennett, Tom E. 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 W{\"u}rthner, Frank and Steffen, Andreas and Marder, Todd B. and Braunschweig, Holger}, title = {Near-Infrared Quadrupolar Chromophores Combining Three-Coordinate Boron-Based Superdonor and Superacceptor Units}, series = {Angewandte Chemie, International Edition}, journal = {Angewandte Chemie, International Edition}, doi = {10.1002/anie.201900889}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-180391}, year = {2019}, abstract = {In this work, two new quadrupolar A-π-D-π-A chromophores have been prepared featuring a strongly electron- donating diborene core and strongly electron-accepting dimesitylboryl F(BMes2) and bis(2,4,6-tris(trifluoromethyl)phenyl)boryl (BMes2) 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 possess 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, respectively, and very high extinction coefficients of ca. 120,000 M-1cm-1. Both molecules also display weak near-IR fluorescence with small Stokes shifts.}, language = {en} } @article{FarrellGrandeSchmidtetal.2019, author = {Farrell, Jeffrey M. and Grande, Vincenzo and Schmidt, David and W{\"u}rthner, Frank}, title = {A Highly Warped Heptagon-Containing sp\(^2\) Carbon Scaffold via Vinylnaphthyl π-Extension}, series = {Angewandte Chemie International Edition}, volume = {58}, journal = {Angewandte Chemie International Edition}, number = {46}, doi = {10.1002/anie.201909975}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-206682}, pages = {16504-16507}, year = {2019}, abstract = {A new strategy is demonstrated for the synthesis of warped, negatively curved, all-sp\(^2\)-carbon π-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 π-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.}, language = {en} } @article{WenNowakKrolNagleretal.2019, author = {Wen, Xinbo and Nowak-Kr{\´o}l, Agnieszka and Nagler, Oliver and Kraus, Felix and Zhu, Na and Zheng, Nan and M{\"u}ller, Matthias and Schmidt, David and Xie, Zengqi and W{\"u}rthner, Frank}, title = {Tetrahydroxy-perylene bisimide embedded in zinc oxide thin film as electron transporting layer for high performance non-fullerene organic solar cells}, series = {Angewandte Chemie International Edition}, volume = {58}, journal = {Angewandte Chemie International Edition}, number = {37}, doi = {10.1002/anie.201907467}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-204723}, pages = {13051-13055}, year = {2019}, 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.}, language = {en} } @article{SchmidtStolteSuessetal.2019, author = {Schmidt, David and Stolte, Matthias and S{\"u}ß, Jasmin and Liess, Dr. Andreas and Stepanenko, Vladimir and W{\"u}rthner, Frank}, title = {Protein-like enwrapped perylene bisimide chromophore as bright microcrystalline emitter material}, series = {Angewandte Chemie International Edition}, volume = {58}, journal = {Angewandte Chemie International Edition}, number = {38}, doi = {10.1002/ange.201907618}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-204809}, pages = {13385-13389}, year = {2019}, 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.}, language = {en} } @article{MezaChinchaLindnerSchindleretal.2020, author = {Meza-Chincha, Ana-Lucia and Lindner, Joachim O. and Schindler, Dorothee and Schmidt, David and Krause, Ana-Maria and R{\"o}hr, Merle I. S. and Mitrić, Roland and W{\"u}rthner, Frank}, title = {Impact of substituents on molecular properties and catalytic activities of trinuclear Ru macrocycles in water oxidation}, issn = {2041-6539}, doi = {10.1039/d0sc01097a}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-204653}, year = {2020}, 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.}, language = {en} } @article{HechtLeowanawatGerlachetal.2020, author = {Hecht, Markus and Leowanawat, Pawaret and Gerlach, Tabea and Stepanenko, Vladimir and Stolte, Matthias and Lehmann, Matthias and W{\"u}rthner, Frank}, title = {Self-Sorting Supramolecular Polymerization: Helical and Lamellar Aggregates of Tetra-Bay-Acyloxy Perylene Bisimide}, series = {Angewandte Chemie International Edition}, volume = {59}, journal = {Angewandte Chemie International Edition}, number = {39}, doi = {10.1002/anie.202006744}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-224586}, pages = {17084 -- 17090}, year = {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.}, language = {en} } @article{WehnerRoehrStepanenkoetal.2020, author = {Wehner, Marius and R{\"o}hr, Merle Insa Silja and Stepanenko, Vladimir and W{\"u}rthner, Frank}, title = {Control of self-assembly pathways toward conglomerate and racemic supramolecular polymers}, series = {Nature Communications}, volume = {11}, journal = {Nature Communications}, doi = {10.1038/s41467-020-19189-8}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-230580}, year = {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. Homo- and heterochiral aggregation is a process of interest to prebiotic and chiral separation chemistry. Here, the authors analyze the self-assembly of a racemic mixture into 1D supramolecular polymers and find homochiral aggregation into conglomerates under kinetic control, while under thermodynamic control a racemic polymer is formed.}, language = {en} }