Molecular Structure and Photochemistry of (<i>E</i>)- and (<i>Z</i>)-Ethyl 3-(2-Indolyl)propenoate. Ground State Conformational Control of Photochemical Behavior and One-Way <i>E</i> → Z Photoisomerization
作者:Frederick D. Lewis、Jye-Shane Yang
DOI:10.1021/jp960907c
日期:1996.1.1
photoisomerization of (E)- and (Z)-ethyl 3-(2-indolyl)propenoate, two methylated indole derivatives, and their N,N-dimethylamide analog have been investigated. The E ester exists in the ground state as a mixture of anti and syn rotational isomers. The spectroscopic and photochemical behaviors of the individual anti and syn conformers were characterized with the assistance of comparisons with the behavior of the methylated
研究了3-(2-吲哚基)丙酸酯的(E)-和(Z)-乙基,两种甲基化的吲哚衍生物及其N,N-二甲基酰胺类似物的分子结构,电子光谱和光异构化。所述ê酯存在于地面状态的反混合物与顺式旋转异构。通过与甲基化的吲哚衍生物的行为比较来表征各个反式和顺式构象异构体的光谱和光化学行为。E的主要反构象体酯吸收和发射的波长比次要顺式构象异构体短。反构象异构体的单线态异构化速率常数实质上大于同构构象异构体的速率常数,导致反构象异构体的单线态寿命更短,荧光量子产率更小。E酰胺在基态和激发态下的行为均与酯相似。酯和酰胺的Z异构体具有相对强的分子内氢键。在非极性溶剂中,它们的单重态荧光弱,光异构化效率低。因此,在非极性溶剂中获得了高度富含Z异构体的光平稳态。辐照后观察到的红移无结构发射EPA或甲基环己烷玻璃中的Z酰胺在77 K时归因于通过分子内氢转移形成的激发态互变异构体。