@article{WuerthnerMezaChinchaSchindleretal.2021,
  author    = {W{\"u}rthner, Frank and Meza-Chincha, Ana-Lucia and Schindler, Dorothee and Natali, Mirco},
  title     = {Effects of Photosensitizers and Reaction Media on Light-Driven Water Oxidation with Trinuclear Ruthenium Macrocycles},
  series = {ChemPhotoChem},
  volume    = {5},
  journal   = {ChemPhotoChem},
  number    = {2},
  doi       = {10.1002/cptc.202000133},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-230116},
  pages     = {173-183},
  year      = {2021},
  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-CH\(_2\)NMe\(_2\)-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.},
  language  = {en}
}
@article{WuerthnerNoll2021,
  author    = {W{\"u}rthner, Frank and Noll, Niklas},
  title     = {A Calix[4]arene-Based Cyclic Dinuclear Ruthenium Complex for Light-Driven Catalytic Water Oxidation},
  series = {Chemistry - A European Journal},
  volume    = {27},
  journal   = {Chemistry - A European Journal},
  number    = {1},
  doi       = {10.1002/chem.202004486},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-230030},
  pages     = {444-450},
  year      = {2021},
  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)\(_3\)]Cl\(_2\) 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.},
  language  = {en}
}
@article{SchindlerGil‐SepulcreLindneretal.2020,
  author    = {Schindler, Dorothee and Gil-Sepulcre, Marcos and Lindner, Joachim O. and Stepanenko, Vladimir and Moonshiram, Dooshaye and Llobet, Antoni and W{\"u}rthner, Frank},
  title     = {Efficient Electrochemical Water Oxidation by a Trinuclear Ru(bda) Macrocycle Immobilized on Multi-Walled Carbon Nanotube Electrodes},
  series = {Advanced Energy Materials},
  volume    = {10},
  journal   = {Advanced Energy Materials},
  number    = {43},
  doi       = {10.1002/aenm.202002329},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-218381},
  year      = {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\(^{-1}\).},
  language  = {en}
}
@article{BoldStolteShoyamaetal.2022,
  author    = {Bold, Kevin and Stolte, Matthias and Shoyama, Kazutaka and Holzapfel, Marco and Schmiedel, Alexander and Lambert, Christoph and W{\"u}rthner, Frank},
  title     = {Macrocyclic donor-acceptor dyads composed of a perylene bisimide dye surrounded by oligothiophene bridges},
  series = {Angewandte Chemie Internationale Edition},
  volume    = {61},
  journal   = {Angewandte Chemie Internationale Edition},
  number    = {1},
  doi       = {10.1002/anie.202113598},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-256569},
  year      = {2022},
  abstract  = {Two macrocyclic architectures comprising oligothiophene strands that connect the imide positions of a perylene bisimide (PBI) dye have been synthesized via a platinum-mediated cross-coupling strategy. The crystal structure of the double bridged PBI reveals all syn-arranged thiophene units that completely enclose the planar PBI chromophore via a 12-membered macrocycle. 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 F{\"o}rster Resonance Energy Transfer and photoinduced electron transfer, thereby leading to extremely low fluorescence quantum yields even in the lowest polarity cyclohexane solvent.},
  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{SchneiderSeebauerBeuerleetal.2024,
  author    = {Schneider, Tilman and Seebauer, Florian and Beuerle, Florian and W{\"u}rthner, Frank},
  title     = {A monodisperse, end-capped Ru(bda) oligomer with outstanding performance in heterogeneous electrochemical water oxidation},
  series = {Advanced Materials Technologies},
  volume    = {9},
  journal   = {Advanced Materials Technologies},
  number    = {11},
  issn      = {2365-709X},
  doi       = {10.1002/admt.202301721},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-363133},
  year      = {2024},
  abstract  = {AbstractWater 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 × 10\(^6\), at a current density of 43.8 mA cm\(^{-2}\) and a potential of 1.45 V versus normal hydrogen electrode (NHE).},
  language  = {en}
}
@article{DostalFennelKochetal.2018,
  author    = {Dost{\´a}l, Jakub and Fennel, Franziska and Koch, Federico and Herbst, Stefanie and W{\"u}rthner, Frank and Brixner, Tobias},
  title     = {Direct observation of exciton-exciton interactions},
  series = {Nature Communications},
  volume    = {9},
  journal   = {Nature Communications},
  doi       = {10.1038/s41467-018-04884-4},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-226271},
  year      = {2018},
  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.},
  language  = {en}
}
@article{DietzschBialasBandorfetal.2022,
  author    = {Dietzsch, Julia and Bialas, David and Bandorf, Johannes and W{\"u}rthner, Frank and H{\"o}bartner, Claudia},
  title     = {Tuning Exciton Coupling of Merocyanine Nucleoside Dimers by RNA, DNA and GNA Double Helix Conformations},
  series = {Angewandte Chemie International Edition},
  journal   = {Angewandte Chemie International Edition},
  doi       = {10.1002/anie.202116783},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-254565},
  pages     = {e202116783},
  year      = {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, - 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.},
  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}
}
@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{SyamalaWuerthner2020,
  author    = {Syamala, Pradeep P. N. and W{\"u}rthner, Frank},
  title     = {Modulation of the Self-Assembly of π-Amphiphiles in Water from Enthalpy- to Entropy-Driven by Enwrapping Substituents},
  series = {Chemistry - A European Journal},
  volume    = {26},
  journal   = {Chemistry - A European Journal},
  number    = {38},
  doi       = {10.1002/chem.202000995},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-218107},
  pages     = {8426 -- 8434},
  year      = {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.},
  language  = {en}
}
@article{NollGrossShoyamaetal.2023,
  author    = {Noll, Niklas and Groß, Tobias and Shoyama, Kazutaka and Beuerle, Florian and W{\"u}rthner, Frank},
  title     = {Folding-Induced Promotion of Proton-Coupled Electron Transfers via Proximal Base for Light-Driven Water Oxidation},
  series = {Angewandte Chemie International Edition},
  volume    = {62},
  journal   = {Angewandte Chemie International Edition},
  number    = {7},
  doi       = {10.1002/anie.202217745},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-312020},
  year      = {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 H\(_{2}\)O in the WNA mechanism.},
  language  = {en}
}
@article{SchnitzleinMuetzelShoyamaetal.2022,
  author    = {Schnitzlein, Matthias and M{\"u}tzel, Carina and Shoyama, Kazutaka and Farrell, Jeffrey M. and W{\"u}rthner, Frank},
  title     = {PAHs Containing both Heptagon and Pentagon: Corannulene Extension by [5+2] Annulation},
  series = {European Journal of Organic Chemistry},
  volume    = {2022},
  journal   = {European Journal of Organic Chemistry},
  number    = {5},
  doi       = {10.1002/ejoc.202101273},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-262627},
  year      = {2022},
  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.},
  language  = {en}
}
@article{SchlossarekStepanenkoBeuerleetal.2022,
  author    = {Schlossarek, Tim and Stepanenko, Vladimir and Beuerle, Florian and W{\"u}rthner, Frank},
  title     = {Self-assembled Ru(bda) Coordination Oligomers as Efficient Catalysts for Visible Light-Driven Water Oxidation in Pure Water},
  series = {Angewandte Chemie International Edition},
  volume    = {61},
  journal   = {Angewandte Chemie International Edition},
  number    = {52},
  doi       = {10.1002/anie.202211445},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-312184},
  year      = {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.},
  language  = {en}
}
@article{KimSchembriBialasetal.2022,
  author    = {Kim, Jin Hong and Schembri, Tim and Bialas, David and Stolte, Matthias and W{\"u}rthner, Frank},
  title     = {Slip-Stacked J-Aggregate Materials for Organic Solar Cells and Photodetectors},
  series = {Advanced Materials},
  volume    = {34},
  journal   = {Advanced Materials},
  number    = {22},
  doi       = {10.1002/adma.202104678},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-276537},
  year      = {2022},
  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.},
  language  = {en}
}
@article{SchindlerMezaChinchaRothetal.2021,
  author    = {Schindler, Dorothee and Meza-Chincha, Anna-Lucia and Roth, Maximilian and W{\"u}rthner, Frank},
  title     = {Structure-Activity Relationship for Di- up to Tetranuclear Macrocyclic Ruthenium Catalysts in Homogeneous Water Oxidation},
  series = {Chemistry—A European Journal},
  volume    = {27},
  journal   = {Chemistry—A European Journal},
  number    = {68},
  doi       = {10.1002/chem.202100549},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-256792},
  pages     = {16938-16946},
  year      = {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 \(^{-1}\) to 8.7 \(^{-1}\) and 10.5 s\(^{-1}\) in chemical and 0.6 s\(^{-1}\) to 3.3 \(^{-1}\) and 5.8 \(^{-1}\) 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.},
  language  = {en}
}
@article{FengZhouQiuetal.2022,
  author    = {Feng, Yi and Zhou, Jiadong and Qiu, Honglin and Schnitzlein, Matthias and Hu, Jingtao and Liu, Linlin and W{\"u}rthner, Frank and Xie, Zengqi},
  title     = {Boron-Locked Starazine - A Soluble and Fluorescent Analogue of Starphene},
  series = {Chemistry - A European Journal},
  volume    = {28},
  journal   = {Chemistry - A European Journal},
  number    = {29},
  doi       = {10.1002/chem.202200770},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-276423},
  year      = {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.},
  language  = {en}
}
@article{MenekseRennerMahlmeisteretal.2020,
  author    = {Menekse, Kaan and Renner, Rebecca and Mahlmeister, Bernhard and Stolte, Matthias and W{\"u}rthner, Frank},
  title     = {Bowl-shaped naphthalimide-annulated corannulene as nonfullerene acceptor in organic solar cells},
  series = {Organic Materials},
  volume    = {2},
  journal   = {Organic Materials},
  number    = {3},
  issn      = {2625-1825},
  doi       = {10.1055/s-0040-1714283},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-299095},
  pages     = {229-234},
  year      = {2020},
  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.},
  language  = {en}
}
@article{ShenBialasHechtetal.2021,
  author    = {Shen, Chia-An and Bialas, David and Hecht, Markus and Stepanenko, Vladimir and Sugiyasu, Kazunori and W{\"u}rthner, Frank},
  title     = {Polymorphism in squaraine dye aggregates by self-assembly pathway differentiation: panchromatic tubular dye nanorods versus J-aggregate nanosheets},
  series = {Angewandte Chemie International Edition},
  journal   = {Angewandte Chemie International Edition},
  number    = {21},
  edition   = {60},
  doi       = {10.1002/anie.202102183},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-256443},
  pages     = {11949-11958},
  year      = {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.},
  language  = {en}
}
@unpublished{FerschMalyRueheetal.2023,
  author    = {Fersch, Daniel and Mal{\´y}, Pavel and R{\"u}he, Jessica and Lisinetskii, Victor and Hensen, Matthias and W{\"u}rthner, Frank and Brixner, Tobias},
  title     = {Single-Molecule Ultrafast Fluorescence-Detected Pump-Probe Microscopy},
  doi       = {10.25972/OPUS-31348},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-313485},
  year      = {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 towards 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.},
  subject      = {Fluoreszenz},
  language  = {en}
}
@article{BrustNaglerShoyamaetal.2023,
  author    = {Brust, Felix and Nagler, Oliver and Shoyama, Kazutaka and Stolte, Matthias and W{\"u}rthner, Frank},
  title     = {Organic Light-Emitting Diodes Based on Silandiol-Bay-Bridged Perylene Bisimides},
  series = {Advanced Optical Materials},
  volume    = {11},
  journal   = {Advanced Optical Materials},
  number    = {5},
  doi       = {10.1002/adom.202202676},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-312599},
  year      = {2023},
  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 ππ-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 OSiObridges, 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.},
  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{HerbstSoberatsLeowanawatetal.2018,
  author    = {Herbst, Stefanie and Soberats, Bartolome and Leowanawat, Pawaret and Stolte, Matthias and Lehmann, Matthias and W{\"u}rthner, Frank},
  title     = {Self-assembly of multi-stranded perylene dye J-aggregates in columnar liquid-crystalline phases},
  series = {Nature Communications},
  volume    = {9},
  journal   = {Nature Communications},
  doi       = {10.1038/s41467-018-05018-6},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-319914},
  year      = {2018},
  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.},
  language  = {en}
}
@article{GilSepulcreLindnerSchindleretal.2021,
  author    = {Gil-Sepulcre, Marcos and Lindner, Joachim O. and Schindler, Dorothee and Velasco, Luc{\´i}a and Moonshiram, Dooshaye and R{\"u}diger, Olaf and DeBeer, Serena and Stepanenko, Vladimir and Solano, Eduardo and W{\"u}rthner, Frank and Llobet, Antoni},
  title     = {Surface-promoted evolution of Ru-bda coordination oligomers boosts the efficiency of water oxidation molecular anodes},
  series = {Journal of the American Chemical Society},
  volume    = {143},
  journal   = {Journal of the American Chemical Society},
  number    = {30},
  doi       = {10.1021/jacs.1c04738},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-351514},
  pages     = {11651-11661},
  year      = {2021},
  abstract  = {A new Ru oligomer of formula {[Ru-\(^{II}\)(bda-\(\kappa\)-N\(^2\)O\(^2\))(4,4'-bpy)]\(_{10}\)(4,4'-bpy)}, 10 (bda is [2,2'-bipyridine]-6,6'-dicarbox-ylate 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-\(\pi\) 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'(H\(_2\)O)\(_2\)@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/cm\(^2\) 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.},
  language  = {en}
}
@article{GryszelSchlossarekWuerthneretal.2023,
  author    = {Gryszel, Maciej and Schlossarek, Tim and W{\"u}rthner, Frank and Natali, Mirco and Głowacki, Eric Daniel},
  title     = {Water-soluble cationic perylene diimide dyes as stable photocatalysts for H\(_2\)O\(_2\) evolution},
  series = {ChemPhotoChem},
  volume    = {7},
  journal   = {ChemPhotoChem},
  number    = {9},
  issn      = {2367-0932},
  doi       = {10.1002/cptc.202300070},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-370250},
  year      = {2023},
  abstract  = {Photocatalytic generation of hydrogen peroxide, H\(_2\)O\(_2\), 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 H\(_2\)O\(_2\), an intriguing alternative for on-demand H\(_2\)O\(_2\) 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.},
  language  = {en}
}
@article{HeWuD'Avinoetal.2018,
  author    = {He, Tao and Wu, Yanfei and D'Avino, Gabriele and Schmidt, Elliot and Stolte, Matthias and Cornil, J{\´e}r{\^o}me and Beljonne, David and Ruden, P. Paul and W{\"u}rthner, Frank and Frisbie, C. Daniel},
  title     = {Crystal step edges can trap electrons on the surfaces of n-type organic semiconductors},
  series = {Nature Communications},
  volume    = {9},
  journal   = {Nature Communications},
  doi       = {10.1038/s41467-018-04479-z},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-227957},
  year      = {2018},
  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.},
  language  = {en}
}
@article{GoleStepanenkoRageretal.2018,
  author    = {Gole, Bappaditya and Stepanenko, Vladimir and Rager, Sabrina and Gr{\"u}ne, Matthias and Medina, Dana D. and Bein, Thomas and W{\"u}rthner, Frank and Beuerle, Florian},
  title     = {Microtubular Self-Assembly of Covalent Organic Frameworks},
  series = {Angewandte Chemie International Edition},
  volume    = {57},
  journal   = {Angewandte Chemie International Edition},
  doi       = {10.1002/anie.201708526},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-227373},
  pages     = {846-850},
  year      = {2018},
  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.},
  language  = {en}
}
@article{SolDehmHechtetal.2018,
  author    = {Sol, Jeroen A. H. P. and Dehm, Volker and Hecht, Reinhard and W{\"u}rthner, Frank and Schenning, Albertus P. H. J. and Debije, Michael G.},
  title     = {Temperature-Responsive Luminescent Solar Concentrators: Tuning Energy Transfer in a Liquid Crystalline Matrix},
  series = {Angewandte Chemie International Edition},
  volume    = {57},
  journal   = {Angewandte Chemie International Edition},
  doi       = {10.1002/anie.201710487},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-238778},
  pages     = {1030-1033},
  year      = {2018},
  abstract  = {Temperature-responsive luminescent solar concentrators (LSCs) have been fabricated in which the F{\"o}rster 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.},
  language  = {en}
}
@article{GarainShoyamaGinderetal.2024,
  author    = {Garain, Swadhin and Shoyama, Kazutaka and Ginder, Lea-Marleen and S{\´a}rosi, Menyh{\´a}rt and W{\"u}rthner, Frank},
  title     = {The delayed box: biphenyl bisimide cyclophane, a supramolecular nano-environment for the efficient generation of delayed fluorescence},
  series = {Journal of the American Chemical Society},
  volume    = {146},
  journal   = {Journal of the American Chemical Society},
  number    = {31},
  issn      = {0002-7863},
  doi       = {10.1021/jacs.4c07730},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-370385},
  pages     = {22056-22063},
  year      = {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 10\(^4\) 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.},
  language  = {en}
}