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首页> 外文期刊>The journal of physical chemistry, A. Molecules, spectroscopy, kinetics, environment, & general theory >The Photochemistry of cis-ortho-, meta-, and para-Aminostilbenes
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The Photochemistry of cis-ortho-, meta-, and para-Aminostilbenes

机译：顺，邻，间和对氨基苯乙烯的光化学

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摘要

The photochemical behavior of the three isomers of cis-aminostilbene is reported here and compared to that of cis-stilbene as well as the corresponding trans-alninostilbenes. The absorption spectra of cis-, ortho-, and meta-aminostilbene are characterized by multiple low oscillator strength bands as a result of symmetry- induced configuration interaction. Fluorescence is observed for cis-meta-aminostilbene but not for the other two isomers, even at 77 K. The fluorescence spectrum of cis-meta-arninostilbene at 77 K is broad and red shifted relative to that of the trans isomer with a large Stokes shift, and its singlet lifetime in methyltetrahydrofuran at 77 K is 17.4 ns. The photocyclization quantum yield for cis-meta-arninostilbene in cyclohexane solution is the largest measured for a monosubstituted cis-stilbene and the photoisomerization quantum yield is unusually low. In contrast, the photochelnical behavior of the ortho and para isomers is similar to that of most substituted cis-stilbenes and is dominated by photoisomerization. The excited-state potential energy surface for cis-meta-aminostilbene is proposed to be perturbed, as in the case of trans-meta- arninostilbene, resulting in striking differences in the photochemical behavior of the three positional isomers. The photochemical behavior of the ortho and para isomers is dominated at low temperatures by a nonradiative channel that has been observed for other substituted cis-stilbenes.
机译：此处报道了顺式-氨基二苯乙烯的三个异构体的光化学行为，并将其与顺式-二苯乙烯和相应的反式-亚硝基苯二酚的光化学行为进行了比较。由于对称诱导的构型相互作用，顺-，邻-和间-氨基二苯乙烯的吸收光谱的特征在于多个低振荡器强度带。即使在77 K时，也观察到顺式-间氨基二苯乙烯的荧光，而其他两种异构体均未观察到荧光。相对于具有较大Stokes的反式异构体，顺式-亚氨基二苯乙烯的荧光光谱宽且红移。位移，其在77 K甲基四氢呋喃中的单重态寿命为17.4 ns。环己烷溶液中顺式-间-亚氨基二苯乙烯的光环化量子产率最大，单取代的顺式-二苯乙烯的光环化量子产率低，光异构化的量子产率异常低。相反，邻位和对位异构体的光化学行为与大多数取代的顺式-苯乙烯衍生物相似，并且受光异构化控制。与反式间亚氨基二苯乙烯一样，提议对顺式-间氨基二苯乙烯的激发态势能表面进行扰动，从而导致三种位置异构体的光化学行为出现显着差异。在低温下，邻位和对位异构体的光化学行为受非辐射通道的支配，该通道已被其他取代的顺式-苯乙烯衍生物观察到。

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