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Indexed by:期刊论文

Date of Publication:2012-03-01

Journal:JOURNAL OF MOLECULAR MODELING

Included Journals:SCIE、PubMed、Scopus

Volume:18

Issue:3

Page Number:937-945

ISSN No.:1610-2940

Key Words:Hydrogen-bonding dynamics; Excited state; Hydrogen bond strengthening; Spectral shift

Abstract:In the present work, in order to investigate the electronic excited-state intermolecular hydrogen bonding between the chromophore coumarin 153 (C153) and the room-temperature ionic liquid N, N-dimethylethanolammonium formate (DAF), both the geometric structures and the infrared spectra of the hydrogen-bonded complex C153-DAF(+) in the excited state were studied by a time-dependent density functional theory (TDDFT) method. We theoretically demonstrated that the intermolecular hydrogen bond C-1=O-1 center dot center dot center dot H-1-O-3 in the hydrogen-bonded C153-DAF(+) complex is significantly strengthened in the S-1 state by monitoring the spectral shifts of the C=O group and O-H group involved in the hydrogen bond C-1=O-1 center dot center dot center dot H-1-O-3. Moreover, the length of the hydrogen bond C-1=O-1 center dot center dot center dot H-1-O-3 between the oxygen atom and hydrogen atom decreased from 1.693 angstrom to 1.633 angstrom upon photoexcitation. This was also confirmed by the increase in the hydrogen-bond binding energy from 69.92 kJ mol(-1) in the ground state to 90.17 kJ mol(-1) in the excited state. Thus, the excited-state hydrogen-bond strengthening of the coumarin chromophore in an ionic liquid has been demonstrated theoretically for the first time.