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Solvent‐dependent structural dynamics of 2(1 H )‐pyridinone in light absorbing S 4 (ππ*) state
Author(s) -
Zhang TengShuo,
Du Rui,
Zhao YanYin,
Xue JiaDan,
Wang HuiGang,
Zheng Xuming
Publication year - 2016
Publication title -
journal of raman spectroscopy
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.748
H-Index - 110
eISSN - 1097-4555
pISSN - 0377-0486
DOI - 10.1002/jrs.4784
Subject(s) - raman spectroscopy , tautomer , chemistry , resonance (particle physics) , excited state , acetonitrile , enol , analytical chemistry (journal) , resonance raman spectroscopy , spectral line , stereochemistry , atomic physics , optics , organic chemistry , physics , catalysis , astronomy
The B‐band resonance Raman spectra of 2(1 H )‐pyridinone (NHP) in water and acetonitrile were obtained, and their intensity patterns were found to be significantly different. To explore the underlying excited state tautomeric reaction mechanisms of NHP in water and acetonitrile, the vibrational analysis was carried out for NHP, 2(1 D )‐pyridinone (NDP), NHP–(H 2 O) n ( n = 1, 2) clusters, and NDP–(D 2 O) n ( n = 1, 2) clusters on the basis of the FT‐Raman experiments, the B3LYP/6‐311++G(d,p) computations using PCM solvent model, and the normal mode analysis. Good agreements between experimental and theoretically predicted frequencies and intensities in different surrounding environments enabled reliable assignments of Raman bands in both the FT‐Raman and the resonance Raman spectra. The results indicated that most of the B‐band resonance Raman spectra in H 2 O was assignable to the fundamental, overtones, and combination bands of about ten vibration modes of ring‐type NHP–(H 2 O) 2 cluster, while most of the B‐band resonance Raman spectra in CH 3 CN was assigned to the fundamental, overtones, and combination bands of about eight vibration modes of linear‐type NHP–CH 3 CN. The solvent effect of the excited state enol‐keto tautomeric reaction mechanisms was explored on the basis of the significant difference in the short‐time structural dynamics of NHP in H 2 O and CH 3 CN. The inter‐molecular and intra‐molecular ESPT reaction mechanisms were proposed respectively to explain the Franck–Condon region structural dynamics of NHP in H 2 O and CH 3 CN.Copyright © 2015 John Wiley & Sons, Ltd.