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Indexed by:期刊论文

Date of Publication:2014-11-15

Journal:JOURNAL OF PHOTOCHEMISTRY AND PHOTOBIOLOGY A-CHEMISTRY

Included Journals:SCIE、Scopus

Volume:294

Page Number:81-87

ISSN No.:1010-6030

Key Words:Hydrogen bond; TDDFT; Absorption spectra; Intramolecular electron transfer excitation

Abstract:The excited hydrogen bonding between hydroxy coumarin (HC) and hydroxy coumarin/methyl imidazole (HCMI) has been studied using TDDFT method. The intermolecular hydrogen bond O-H center dot center dot center dot N-H is strengthened upon intramolecular electron transfer (ICT) excitation. The calculated ultraviolet absorption spectrum is in good agreement with the experimental data, and the experimental peak at 310 nm is predicted to be the excited S-1 state. From the frontier molecular orbitals of HCMI, the HOMO and the LUMO are of pi and pi* character and the transition from the ground state to the S-1 state is a local exciting process. The intramolecular electron transfer of pi electron from the -OH group to an pi* orbital of -C8CF3 group not to C=O group is found upon ICT excitation. The calculated gap between HOMO and LUMO shows that HCMI can be more easily excited than free HC. The hydrogen bonding can modulate the internal conversion rate of HCMI. (C) 2014 Elsevier B.V. All rights reserved.