Refine
Has Fulltext
- yes (60)
Is part of the Bibliography
- yes (60)
Year of publication
Document Type
- Journal article (58)
- Preprint (2)
Language
- English (60)
Keywords
- water oxidation (8)
- dyes (5)
- photocatalysis (5)
- polycyclic aromatic hydrocarbons (5)
- self-assembly (5)
- fluorescence (4)
- perylene bisimide (4)
- aggregation (3)
- aromaticity (3)
- artificial photosynthesis (3)
- catalysis (3)
- dyes/pigments (3)
- exciton coupling (3)
- homogeneous catalysis (3)
- macrocycles (3)
- organic chemistry (3)
- organic photodiodes (3)
- photoinduced electron transfer (3)
- supramolecular chemistry (3)
- J‐aggregates (2)
- Ruthenium complexes (2)
- absorption (2)
- annulation (2)
- azulene (2)
- boron (2)
- chirality transfer (2)
- corannulene (2)
- crystal engineering (2)
- cyclophanes (2)
- homogenous catalysis (2)
- luminescence (2)
- merocyanines (2)
- nanographene (2)
- organic light emitting diodes (2)
- organic semiconductors (2)
- organic solar cells (2)
- pentacene (2)
- perylene bisimides (2)
- phosphorescence (2)
- polymerization (2)
- renewable fuels (2)
- ruthenium (2)
- ruthenium complexes (2)
- solid-state emitters (2)
- spectroscopy (2)
- squaraine dyes (2)
- water (2)
- AIE (1)
- Aromatic-hydrocarbon (1)
- C-C coupling (1)
- Carbon (1)
- Chemie (1)
- Chromophore Assembly (1)
- Corannulene (1)
- Dimers (1)
- Dyes (1)
- Fluorescence (1)
- Fluoreszenz (1)
- Functionalization (1)
- Graphene nanoribbons (1)
- J-aggregate behavior (1)
- J-aggregates (1)
- K2–K model (1)
- Liquid-crystalline (1)
- Marcus inverted region (1)
- Merocyanine (1)
- Molecular-dynamics (1)
- Nucleic Acids (1)
- Nucleobase Analogue (1)
- OEG chains (1)
- Organische Chemie (1)
- PBI cyclophane (1)
- PI stacking (1)
- Pathway (1)
- Potential-energy curves (1)
- Simulations (1)
- Single-molecule microscopy (1)
- Sracking (1)
- State (1)
- Supramolecular Element (1)
- Suzuki coupling (1)
- Systems (1)
- Ultrafast spectroscopy (1)
- \(\alpha\)-phase (1)
- \(\beta\)-phase (1)
- aelf-assembly (1)
- amphiphilic dyes (1)
- amplification (1)
- annihilation (1)
- aqua material (1)
- aqueous medium (1)
- arenes (1)
- association (1)
- boric acid (1)
- boronate esters (1)
- bulk-heterojunction solar cells (1)
- carbon (1)
- carrier transport (1)
- cascade reactions (1)
- catalyst (1)
- catalyst synthesis (1)
- catalysts (1)
- catalytic (1)
- catalytic activity (1)
- catalytic mechanisms (1)
- charge transport (1)
- charge transport; hydrogen bonding; oligothiophene; organogel; self-assembly (1)
- chirality (1)
- circular polarized luminescence (1)
- cocrystallization (1)
- complexity (1)
- conjugated molecule (1)
- conjugation (1)
- cooperative self-assembly (1)
- coordination chemistry (1)
- coordination oligomer (1)
- covalent organic framework (1)
- cristal engeneering (1)
- crystalline (1)
- crystals (1)
- curvature (1)
- curved π-systems (1)
- cyclic perylene bisimide (1)
- cyclodehydrogenation (1)
- cylindrical micelles (1)
- deracemization (1)
- diffusion (1)
- dimerization (1)
- dinuclear (1)
- dipole-dipole interaction (1)
- donor-acceptor dyad (1)
- donor–acceptor dyads (1)
- duplex structure (1)
- dye assembly (1)
- electrocatalysis (1)
- electronic structure (1)
- emission (1)
- energy transfer (1)
- enzyme (1)
- excimer (1)
- excimer formation (1)
- films (1)
- flourescence quantum yield (1)
- fluorescent (1)
- folded macrocyles (1)
- folding (1)
- growth (1)
- heterogeneous catalysis (1)
- hydrocarbons (1)
- hydroxylation (1)
- imidization (1)
- induced phase transition (1)
- kinetics (1)
- ligands (1)
- liquid crystals (1)
- low-valent compounds (1)
- macrocycle (1)
- materials (1)
- materials design (1)
- mechanism (1)
- merocyanine (1)
- merocyanine dyes/pigments (1)
- metal complexenes (1)
- metallomacrocycles (1)
- migration (1)
- mobility (1)
- molecular (1)
- molecular capsules (1)
- molecules (1)
- multichromophores (1)
- nanoparticles (1)
- nanorods and nanosheets (1)
- naphthalene diimide (1)
- narrow bandwidth (1)
- near infrared emitter (1)
- near-IR chromophores (1)
- near-infrared sensitivity (1)
- non-fullerene acceptors (1)
- noncovalent interactions (1)
- nonfullerene acceptors (1)
- nucleation elongation (1)
- nucleation-elongation (1)
- oligothiophene (1)
- oligothiophenes (1)
- optical materials (1)
- organic compounds (1)
- organization (1)
- oxidation (1)
- peptide backbone (1)
- perylene bisimide dyes (1)
- perylene bisimide hydrogels (1)
- perylene bismide dye (1)
- perylene dyes (1)
- perylene imide (1)
- perylenebisimide (1)
- perylenebisimide dyes (1)
- photoconductive interlayer (1)
- photoluminescence (1)
- photon‐correlation (1)
- photosenitizers (1)
- platinum complexes (1)
- polycycles (1)
- polymorphism (1)
- quantum chemical analysis (1)
- reabsorption (1)
- rigidification (1)
- room-temperature phosphorescence (RTP) (1)
- rotational diffusion (1)
- ruthenium bda complexes (1)
- ruthenium catalysts (1)
- single crystal structure (1)
- single photon emission (1)
- social self‐sorting (1)
- solar cells (1)
- solar fuels (1)
- solid‐state emission (1)
- solvent effects (1)
- solvent-dependent fluorescence yield (1)
- stability (1)
- starazine (1)
- starphene analogue (1)
- stereochemistry (1)
- structural dynamics (1)
- structure elucidation (1)
- supramolecular materials (1)
- supramolecular polymers (1)
- sustainable energy source (1)
- synthesis (1)
- systems (1)
- template catalysis (1)
- thermodynamics (1)
- thin-film transistors (1)
- time-resolved impulsive stimulated raman spectroscopy (1)
- triarylborane (1)
- trinuclear (1)
- triplet (1)
- triplet sensitization (1)
- two-dimensional nanostructures (1)
- upramolecular polymerization process (1)
- vacuum processable (1)
- vibrational coherence (1)
- water splitting (1)
- π-conjugated systems (1)
- π-π-interactions (1)
- π–π Stacking (1)
Institute
Sonstige beteiligte Institutionen
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.
Activating Organic Phosphorescence via Heavy Metal–π Interaction Induced Intersystem Crossing
(2022)
Heavy‐atom‐containing clusters, nanocrystals, and other semiconductors can sensitize the triplet states of their surface‐bonded chromophores, but the energy loss, such as nonradiative deactivation, often prevents the synergistic light emission in their solid‐state coassemblies. Cocrystallization allows new combinations of molecules with complementary properties for achieving functionalities not available in single components. Here, the cocrystal formation that employs platinum(II) acetylacetonate (Pt(acac)\(_{2}\)) as a triplet sensitizer and electron‐deficient 1,4,5,8‐naphthalene diimides (NDIs) as organic phosphors is reported. The hybrid cocrystals exhibit room‐temperature phosphorescence confined in the low‐lying, long‐lived triplet state of NDIs with photoluminescence (PL) quantum yield (Φ\(_{PL}\)) exceeding 25% and a phosphorescence lifetime (τ\(_{Ph}\)) of 156 µs. This remarkable PL property benefits from the noncovalent electronic and spin–orbital coupling between the constituents.
Single crystals of three at bay area tetraphenoxy‐substituted perylene bisimide dyes are grown by vacuum sublimation. X‐ray analysis reveals the self‐assembly of these highly twisted perylene bisimides (PBIs) in the solid state via imide–imide hydrogen bonding into hydrogen‐bonded PBI chains. The crystallographic insights disclose that the conformation and sterical congestion imparted by the phenoxy substituents can be controlled by ortho‐substituents. Accordingly, whilst sterically less demanding methyl and isopropyl substituents afford double‐stranded PBI chains of complementary P and M atropo‐enantiomers, single hydrogen‐bonded chains of homochiral PBIs are observed for the sterically more demanding ortho‐phenyl substituents. Investigation of the absorption and fluorescence properties of microcrystals and thin films of these PBIs allow for an unambiguous interpretation of these exciton systems. Thus, the J‐aggregates of the double‐stranded crystals exhibit a much larger (negative) exciton coupling than the single‐stranded one, which in contrast has the higher solid‐state fluorescence quantum yield.
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.
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.
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.
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.
Many dyes suffer from fast non-radiative decay pathways, thereby showing only short-lived excited states and weak photoluminescence. Here we show a pronounced fluorescence enhancement for a weakly fluorescent merocyanine (MC) dye by being co-facially stacked to other dyes in hetero-folda-trimer architectures. By means of fluorescence spectroscopy (lifetime, quantum yield) the fluorescence enhancement was explained by the rigidification of the emitting chromophore in the defined foldamer architecture and the presence of a non-forbidden lowest exciton state in H-coupled hetero-aggregates. This folding-induced fluorescence enhancement (FIFE) for specific sequences of π-stacked dyes points at a viable strategy toward improved fluorophores that relates to the approach used by nature in the green fluorescent protein (GFP).
Palladium‐catalyzed [5+2] annulation of 1‐boraphenalenes with ortho‐dihaloarenes afforded negatively curved π‐extended pleiadienes. Two benzo[1,2‐i:4,5‐i’]dipleiadienes (BDPs) featuring a seven‐six‐seven‐membered ring arrangement were synthesized and investigated. Their crystal structure revealed a unique packing arrangement and theoretical calculations were employed to shed light onto the dynamic behavior of the BDP moiety and its aromaticity. Further, a naphthalene‐fused pleiadiene was stitched together by oxidative cyclodehydrogenation to yield an additional five‐membered ring. This formal azulene moiety led to distinct changes in optical and redox properties and increased perturbation of the aromatic system.
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.