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论文类型：期刊论文

发表时间：2014-04-01

发表刊物：CANADIAN JOURNAL OF CHEMISTRY

收录刊物：SCIE、EI、Scopus

卷号：92

期号：4

页面范围：274-278

ISSN号：0008-4042

关键字：excited state intramolecular proton transfer (ESIPT); intramolecular charge transfer (ICT); fluorescence; time-dependent density functional theory (TDDFT); paeonol

摘要：An excited-state intramolecular proton transfer (ESIPT) coupled charge transfer reaction of paeonol was investigated both experimentally and theoretically. The ESIPT reaction of paeonol was predicted based on the large Stokes shift, which is observed in steady-state absorption and fluorescence spectra in an ethanol solution. The steady-state spectra in some solutions, such as methanol, ethanol, propanol, dichloromethane, and n-hexane, illustrate that the ESIPT reaction of paeonol has no dependence on the solvent properties. Therefore, the excited-state intermolecular proton transfer cannot be generated in protic solvents. Using the density functional theory and time-dependent density functional theory methods, we make a subsequent theoretical calculation that indicates that the ESIPT reaction of paeonol occurs through the intramolecular hydrogen bond O-H center dot center dot center dot O=C. The excited-state potential energy curve of paeonol indicates that the ESIPT reaction is a barrierless process, and the fluorescence emission of paeonol at 493 nm in the ethanol solution was assigned to the keto isomer fluorescence. Additionally, we also found an intramolecular charge transfer in the excited state by analysing the frontier molecular orbitals of paeonol.