Intramolecular photo-driven charge transfer in a series of pyridyl substituted phenyloxazoles. Structural relaxation in meta-substituted ethylpyridinium derivative of phenyloxazole.

Autor: Volchkov VV; Department of Chemistry, M. V. Lomonosov Moscow State University, Leninskie Gory 1-3, Moscow, 119991, Russian Federation. volchkov_vv@mail.ru., Khimich MN; Department of Chemistry, M. V. Lomonosov Moscow State University, Leninskie Gory 1-3, Moscow, 119991, Russian Federation., Rusalov MV; Department of Chemistry, M. V. Lomonosov Moscow State University, Leninskie Gory 1-3, Moscow, 119991, Russian Federation., Gostev FE; N. N. Semenov Institute of Chemical Physics, Russian Academy of Sciences, Kosygina Str. 4, Moscow, 119991, Russian Federation., Shelaev IV; N. N. Semenov Institute of Chemical Physics, Russian Academy of Sciences, Kosygina Str. 4, Moscow, 119991, Russian Federation., Nadtochenko VA; N. N. Semenov Institute of Chemical Physics, Russian Academy of Sciences, Kosygina Str. 4, Moscow, 119991, Russian Federation., Kuzmin VA; N. M. Emmanuel Institute of Biochemical Physics, Russian Academy of Sciences, Kosygina Str. 4, Moscow, 119334, Russian Federation., Kostyukov AA; N. M. Emmanuel Institute of Biochemical Physics, Russian Academy of Sciences, Kosygina Str. 4, Moscow, 119334, Russian Federation., Egorov AE; N. M. Emmanuel Institute of Biochemical Physics, Russian Academy of Sciences, Kosygina Str. 4, Moscow, 119334, Russian Federation., Melnikov MY; Department of Chemistry, M. V. Lomonosov Moscow State University, Leninskie Gory 1-3, Moscow, 119991, Russian Federation.
Jazyk: angličtina
Zdroj: Photochemical & photobiological sciences : Official journal of the European Photochemistry Association and the European Society for Photobiology [Photochem Photobiol Sci] 2021 Nov; Vol. 20 (11), pp. 1419-1428. Date of Electronic Publication: 2021 Sep 29.
DOI: 10.1007/s43630-021-00103-0
Abstrakt: 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.
(© 2021. The Author(s), under exclusive licence to European Photochemistry Association, European Society for Photobiology.)
Databáze: MEDLINE
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