@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{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{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{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{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{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{KirchnerSchrammIvanovaetal.2024,
  author    = {Kirchner, Philipp H. and Schramm, Louis and Ivanova, Svetlana and Shoyama, Kazutaka and W{\"u}rthner, Frank and Beuerle, Florian},
  title     = {A water-stable boronate ester cage},
  series = {Journal of the American Chemical Society},
  volume    = {146},
  journal   = {Journal of the American Chemical Society},
  number    = {8},
  issn      = {0002-7863},
  doi       = {10.1021/jacs.3c12002},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-361245},
  pages     = {5305-5315},
  year      = {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.},
  language  = {en}
}
@article{NollWuerthner2024,
  author    = {Noll, Niklas and W{\"u}rthner, Frank},
  title     = {Bioinspired water preorganization in confined space for efficient water oxidation catalysis in metallosupramolecular ruthenium architectures},
  series = {Accounts of Chemical Research},
  volume    = {57},
  journal   = {Accounts of Chemical Research},
  number    = {10},
  issn      = {0001-4842},
  doi       = {10.1021/acs.accounts.4c00148},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-361232},
  pages     = {1538-1549},
  year      = {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 (CaMn\(_4\)O\(_5\)) 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.},
  language  = {en}
}
@article{WehShoyamaWuerthner2023,
  author    = {Weh, Manuel and Shoyama, Kazutaka and W{\"u}rthner, Frank},
  title     = {Preferential molecular recognition of heterochiral guests within a cyclophane receptor},
  series = {Nature Communications},
  volume    = {14},
  journal   = {Nature Communications},
  doi       = {10.1038/s41467-023-35851-3},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-357750},
  year      = {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.},
  language  = {en}
}
@article{OuyangRueheZhangetal.2022,
  author    = {Ouyang, Guanghui and R{\"u}he, Jessica and Zhang, Yang and Lin, Mei-Jin and Liu, Minghua and W{\"u}rthner, Frank},
  title     = {Intramolecular Energy and Solvent-Dependent Chirality Transfer within a BINOL-Perylene Hetero-Cyclophane},
  series = {Angewandte Chemie International Edition},
  volume    = {61},
  journal   = {Angewandte Chemie International Edition},
  number    = {31},
  doi       = {10.1002/anie.202206706},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-318818},
  year      = {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.},
  language  = {en}
}