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Indexed by:期刊论文

Date of Publication:2013-11-01

Journal:SPECTROCHIMICA ACTA PART A-MOLECULAR AND BIOMOLECULAR SPECTROSCOPY

Included Journals:SCIE、EI、PubMed

Volume:115

Page Number:39-44

ISSN No.:1386-1425

Key Words:Electronic excited state; Hydrogen bond strengthening; Time-dependent density functional theory; Internal conversion

Abstract:Aminopyrazine (AP) and AP-methanol complexes have been theoretically studied by using density functional theory (DFT) and time-dependent density functional theory (TDDFT). The excited-state hydrogen bonds are discussed in detail. In the ground state the intermolecular multiple hydrogen bonds can be formed between AP molecule and protic solvents. The AP monomer and hydrogen-bonded complex of AP with one methanol are photoexcited initially to the S-2 state, and then transferred to the S-1 state via internal conversion. However the complex of AP with two methanol molecules is directly excited to the S-1 state. From the calculated electronic excited energies and simulated absorption spectra, we find that the intermolecular hydrogen bonds are strengthened in the electronic excited states. The strengthening is confirmed by the optimized excited-state geometries. The photochemical processes in the electronic excited states are significantly influenced by the excited-state hydrogen bond strengthening. (C) 2013 Elsevier B.V. All rights reserved.