化学
光化学
分子内力
叠氮
构象异构
光致变色
水杨醛
激发态
互变异构体
发色团
离子
纳秒
分子
结晶学
立体化学
有机化学
原子物理学
席夫碱
光学
物理
激光器
作者
Marcin Ziółek,Michał Gil,Juan Ángel Organero,Abderrazzak Douhal
摘要
The normal and anion structures of salicylaldehyde azine (SAA) in solvents of different viscosities and polarities have been studied by means of femto- to nanosecond time-resolved emission techniques. In the normal form, an excited-state intramolecular proton-transfer (ESIPT) reaction takes place with a time constant shorter than 80 fs to produce an excited keto-type tautomer in which intramolecular-vibrational energy redistribution and vibrational cooling occur in 100 fs to 2 ps. The viscosity-dependent emission decay in the red part of the spectrum with 5–11 ps reflects a twisting motion leading to rotamers of these keto-type structures, most probably of (n,π*) nature. For the anion type, the viscosity dependent rise-times (3 to 400 ps) at the red part of the emission, and the wavelength-dependent fluorescence lifetimes (20 to 1100 ps) indicate a stepwise formation of different conformers of the anions. The results reported here should be relevant to a better understanding of the photobehaviour of photochromic compounds and charged chromophores in biological systems.
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