title: New insights into the dual fluorescence of methyl salicylate: effects of intermolecular hydrogen bonding and solvation.
abstract: In this paper, we propose a new and complete mechanism for dual fluorescence of methyl salicylate (MS) under different conditions using a combined experimental (i.e., steady-state absorption and emission spectra and time-resolved fluorescence spectra) and theoretical (i.e., time-dependent density function theory) study. First, our theoretical study indicates that the barrier height for excited state intramolecular proton transfer (ESIPT) reaction of ketoB depends on the solvent polarity. In nonpolar solvents, the ESIPT reaction of ketoB is barrierless; the barrier height will increase with increasing solvent polarity. Second, we found that, in alcoholic solvents, intermolecular hydrogen bonding plays a more important role. The ketoB form of MS can form two hydrogen bonds with alcoholic solvents; one will facilitate ESIPT and produce the emission band in the blue region; the other one precludes ESIPT and produces the emission band in the near-UV region. Our proposed new mechanism can well explain previous results as well as our new experimental results.
authors.affiliation: State Key Laboratory of Molecular Reaction Dynamics, Dalian Institute of Chemical Physics, Chinese Academy of Sciences , Dalian 116023, Liaoning, China.
authors.forename: Panwang
authors.initials: P
authors.lastname: Zhou
authors.forename: Mark R
authors.initials: MR
authors.lastname: Hoffmann
authors.forename: Keli
authors.initials: K
authors.lastname: Han
authors.forename: Guozhong
authors.initials: G
authors.lastname: He
mesh_terms: D065966:Absorption, Physicochemical; D000438:Alcohols / Q000737:chemistry; D006860:Hydrogen Bonding; D008958:Models, Molecular; D012459:Salicylates / Q000737:chemistry*; D012997:Solvents / Q000737:chemistry*; D013050:Spectrometry, Fluorescence
chemical_list: D000438:Alcohols; D012459:Salicylates; D012997:Solvents; C033069:methyl salicylate