- Molecular Engineering of Chromophores to Enable Triplet-Triplet Annihilation Upconversion
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Triplet-triplet annihilation upconversion (TTA-UC) is an unconventional photophysical process that yields high-energy photons from low-energy incident light and offers pathways for innovation across many technologies, including solar energy harvesting, photochemistry, and optogenetics. Within aromatic organic chromophores, TTA-UC is achieved through several consecutive energy conversion events that ultimately fuse two triplet excitons into a singlet exciton. In chromophores where the singlet exciton is roughly isoergic with two triplet excitons, the limiting step is the triplet-triplet annihilation pathway, where the kinetics and yield depend sensitively on the energies of the lowest singlet and triplet excited states. Herein we report up to 40-fold improvements in upconversion quantum yields using molecular engineering to selectively tailor the relative energies of the lowest singlet and triplet excited states, enhancing the yield of triplet-triplet annihilation and promoting radiative decay of the resulting singlet exciton. Using this general and effective strategy, we obtain upconversion yields with red emission that are among the highest reported, with remarkable chemical stability under ambient conditions.
- Fallon, Kealan J.,Churchill, Emily M.,Sanders, Samuel N.,Shee, James,Weber, John L.,Meir, Rinat,Jockusch, Steffen,Reichman, David R.,Sfeir, Matthew Y.,Congreve, Daniel N.,Campos, Luis M.
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- The photophysical properties of chromophores at high (100 mM and above) concentrations in polymers and as neat solids
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The absorption, fluorescence, and photostability of five conjugated chromophores: perylene, 2,5,8,11-tetra-t-butyl perylene (TTBP), perylene orange (PO), perylene red (PR), and a zwitterionic Meisenheimer complex (MHC), are studied as a function of concentration in poly(methyl methacrylate) (PMMA). At 1 mM concentrations, all five molecules exhibit properties consistent with unaggregated chromophores. At higher concentrations, perylene and PO both exhibit excimer formation, while TTBP, PR, and the MHC retain their monomeric fluorescent lineshapes. In these three molecules, however, the fluorescence decay times decrease by 10% (TTBP) to 50% (MHC) at concentrations of 100 mM in PMMA. The fluorescence properties of these highly concentrated samples are sensitive to the sample preparation conditions. In the neat solid where the effective concentration is on the order of 1 M, all three molecules exhibit very fast fluorescence decays, on the order of 150 ps or less, despite the fact that they retain their basic monomeric fluorescence lineshape. In addition to the enhanced nonradiative decay at high concentrations, these three molecules also undergo a concentration-dependent photobleaching. The combined effects of intermolecular nonradiative decay channels and photobleaching appear to be a general obstacle to achieving highly concentrated dye-doped solids. the Owner Societies 2006.
- Al-Kaysi, Rabih O.,Sang Ahn, Tai,Mueller, Astrid M.,Bardeen, Christopher J.
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- Fluorescence and Absorption Properties of Perylenyl and Perylenoyl Probe Molecules in Solvents and Liquid Crystals
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Light spectroscopic properties of fluorescent derivatives of perylene in solvents lyotropic liquid crystals have been investigated.These were 2,5,8,11-tetra-tert-butylperylene, methyl 4-(3-perylenyl)butyrate, methyl 3-(3-perylenoyl)propionate, 3-(3-perylenoyl)propionic acid, 9-(3-perylenoyl)nonanoic acid, and N-sphingosine-1-phosphocholine.The first two compounds are hereafter referred to as perylenyls, while the latter four are named perylenoyls.Absorption and fluorescence spectra and fluorescence lifetimes of the perylenyls are found to be very similar to those of perylene.Both absorption and fluorescence spectraa of the perylenoyls are broadened and red-shifted compared to those of perylene.The fluorescence spectrum is strongly red-shifted with increasing solvent polarity, which is not the case for the perylenyls.Photophysical data of the perylenyl and the perylenoyl molecules in various solvents, micelles, and liquid crystals are given.It is shown that the absorption and fluorescence dipole moments for the S0 S1 transitions are parallel in both kinds of chromophores.The orientation of these probe molecules in a macroscopically aligned liquid crystal has been obtained from linear dichroism measurements mand time-resolved fluorescence anisotropy.It is concluded that the orientation of a probe in its electronic ground state may differ from that in the excited state.Information about rotational motions of the different fluorophores solubilized in micelles and liquid crystals was obtained from the fluorescence anisotropy.The fluorescent moiety of the probe undergoes rotational motions locally in the amphiphile aggregate which are typically about 1-3 ns.A slower correlation time ranging from 10 to 40 ns is ascribed to translational diffusion of the fluorophore in the aggregate.
- Johansson, Lennart B.-A.,Molotkovsky, Julian G.,Bergelson, Lev D.
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- Synthesis and Properties of Perylene-Bridge-Anchor Chromophoric Compounds
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The quest to control chromophore/semiconductor properties to enable new technologies in energy and information science requires detailed understanding of charge carrier dynamics at the atomistic level, which can often be attained through the use of model systems. Perylene-bridge-anchor compounds are successful models for studying fundamental charge transfer processes on TiO2, which remains among the most commonly investigated and technologically important interfaces, mostly because of perylene's advantageous electronic and optical properties. Nonetheless, the ability to fully exploit synthetically the substitution pattern of perylene with linker (= bridge-anchor) units remains little explored. Here we developed 2,5-di-tert-butylperylene (DtBuPe)-bridge-anchor compounds with t-Bu group substituents to prevent π-stacking and one or two linker units in both the peri and ortho positions, by employing a combination of Friedel-Crafts alkylations, bromination, iridium-catalyzed borylation, and palladium-catalyzed cross-coupling reactions. Photophysical characterization and computational analysis by density functional theory (DFT) and time-dependent DFT (TD-DFT) were carried out on four DtBuPe acrylic acid derivatives with a single or a double linker in peri (12b), ortho (15b), peri,peri (18b), and ortho,ortho (21b). The energies of the unoccupied orbitals {LUMO, LUMO + 1, LUMO + 2} are strongly affected by the presence of a π-conjugated linker, resulting in a stabilization of these states and a red shift of their absorption and emission spectra, as well as the loss of vibronic structure in the spectrum of the peri,peri compound, consistent with the strong bonding character of this substitution pattern.
- Avenoso, Joseph,Doble, Samantha,Fan, Hao,Galoppini, Elena,Gundlach, Lars,Harmer, Ryan,Lloyd, Katherine,Rego, Luis G. C.,Yan, Han
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p. 6330 - 6343
(2020/09/18)
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- Tailoring Colors by O Annulation of Polycyclic Aromatic Hydrocarbons
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The synthesis of O-doped polyaromatic hydro- carbons in which two polycyclic aromatic hydrocarbon sub units are bridged through one or two O atoms has been achieved. This includes high-yield ring-closure key steps that, depending on the reaction condition
- Mileti?, Tanja,Fermi, Andrea,Orfanos, Ioannis,Avramopoulos, Aggelos,De Leo, Federica,Demitri, Nicola,Bergamini, Giacomo,Ceroni, Paola,Papadopoulos, Manthos G.,Couris, Stelios,Bonifazi, Davide
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supporting information
p. 2363 - 2378
(2017/02/23)
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- Experimental fingerprints of vibrational wave-packet motion during ultrafast heterogeneous electron transfer
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By application of 20 fs laser pulses, vibrational wave packets of low-energy modes (mainly 357 and 421 cm-1) were generated in the perylene chromophore that gave rise to periodic beats that lasted longer than 1 ps in transient absorption signals. Electron transfer from the excited singlet state of the perylene chromophore, attached as molecule DTB-Pe via the -CH2-phosphonic acid group to anatase TiO2, was measured in ultrahigh vacuum with a time constant of 75 fs. The vibrational wave packet that was generated in the donor state continued its motion for several hundred femtoseconds in the product state of the reaction, i.e., in the ionized chromophore. This is direct proof for electron transfer occurring from a nonrelaxed vibrational population that was created by the short laser pulse in the donor molecule. The rise of the product state showed a staircase-like time dependence. The steps are attributed to electron transfer that occurs preferentially each time the vibrational wave packet (frequency 480 cm-1) reaches a crossing point for the potential curves of reactant and product state. Such wave-packet modulation of heterogeneous electron transfer can arise if the density of electronic acceptor states in the electrode is changing strongly over an energy range on the order of the reorganization energy below the excited molecular donor orbital.
- Zimmermann,Willig,Ramakrishna,Burfeindt,Pettinger,Eichberger,Storck
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p. 9245 - 9253
(2007/10/03)
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- Polyarylenes and Poly(arylenevinylene)s, V. - Synthesis of Tetraalkyl-Substituted Oligo(1,4-naphthylene)s and Cyclization to Soluble Oligo(peri-naphthylene)s
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A homologous series of oligo(1,4-naphthylene)s from the binaphthyl 6 to the sexinaphthylene derivative 10 were synthesized successively.The Pd(0)-catalyzed reaction between aryl bromides and arylboronic acids was used as a coupling method.By appropriate choice of the stoichiometry, the method allowed isolation of the intermediates 20 and 21.Under the influence of potassium in 1,2-dimethoxyethane the 1,4-bridged naphthylenes 6-10 were partially cyclized to perylene and terrylene units.This anionic cyclization displayed a high regioselectivity.Complete cyclization to the oligorylenes 3b, 4b and 5b was achieved under the influence of AlCl3 and CuCl2 on the bichromophoric systems 24, 25 and 28.The synthetic sequence allowed substitution by tert-butyl groups, so that the oligorylenes 2b, 3b, 4b and 5b were amenable to spectroscopic investigations.The trends in absorption maxima and fluorescence are discussed. Key Words: Perylene / Terrylene / Quaterrylene / Oligorylenes / Oligo(1,4-naphthylene)s
- Koch, Karl-Heinz,Muellen, Klaus
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p. 2091 - 2100
(2007/10/02)
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