Intramolecular photo-driven charge transfer in a series of pyridyl substituted phenyloxazoles. Structural relaxation in meta-substituted ethylpyridinium derivative of phenyloxazole
Autor: | Mikhail Ya. Melnikov, Vladimir A. Kuzmin, Victor A. Nadtochenko, Alexey A. Kostyukov, M. N. Khimich, Ivan V. Shelaev, Fedor E. Gostev, Valery V. Volchkov, Anton E. Egorov, M. V. Rusalov |
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Rok vydání: | 2021 |
Předmět: |
Materials science
Time-dependent density functional theory Fluorescence spectroscopy symbols.namesake chemistry.chemical_compound chemistry Excited state Stokes shift Ultrafast laser spectroscopy symbols Physical chemistry Pyridinium Physical and Theoretical Chemistry Spectroscopy Conformational isomerism |
Zdroj: | Photochemical & Photobiological Sciences. 20:1419-1428 |
ISSN: | 1474-9092 1474-905X |
Popis: | A series of pyridyl (pyridinium) substituted benzoxazoles were studied by steady state absorption, fluorescence spectroscopy, time-resolved fluorescence spectroscopy, fs pulse absorption and polarization spectroscopy, and quantum–chemical calculations. The spectral and kinetic parameters of the fluorophores in MeCN and EtOAc were obtained experimentally and were calculated by means of DFT and TDDFT methods. A scheme including four transient excited states was proposed for the interpretation of differential absorption kinetics of the charged fluorophores. Expressions describing the actual kinetics graphs, the decay associated spectra, and the species-associated spectra were derived. The charge shift step was found to be dependent on average solvation times. A charge shift followed by the formation of the twisted conformer was found for the excited 1-ethyl-3-(5-phenyloxazol-2-yl)pyridinium 4-methyl-1-benzenesulfonate in MeCN and EtOAc. Conformational analysis confirms a large amplitude motion of the meta-substituted ethylpyridinium group as an additional structural relaxation path producing an abnormally large fluorescence Stokes shift. |
Databáze: | OpenAIRE |
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