Kinetic study of the fast thermal cis-to-trans isomerisation of para-, ortho- and polyhydroxyazobenzenes
Kinetic study of the fast thermal cis-to-trans isomerisation of para-, ortho- and polyhydroxyazobenzenes
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DOI：
10.1039/c004340k
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发表时间：
2010-01-01
影响因子：
3.3
通讯作者：
Velasco, Dolores
中科院分区：
文献类型：
--
作者：
Garcia-Amoros, Jaume;Sanchez-Ferrer, Antoni;Velasco, Dolores
研究了对位、邻位和多羟基取代偶氮苯在不同溶剂中的热异构化反应过程。对羟基取代偶氮苯的热还原反应动力学强烈依赖于所用溶剂的性质，在乙醇中的松弛时间从200-300毫秒到在甲苯中的半小时不等。另外，加工速度主要与邻位取代类似物的溶剂性质无关。多羟基取代偶氮苯表现出比对位和邻位单羟基偶氮衍生物更快的动力学。它们在乙醇中的驰豫时间为6-12毫秒，是设计快速光开关器件的最佳分子。所有的羟基偶氮衍生物都通过旋转机制从介稳的顺式异构体转变为热力学稳定的反式异构体。
The thermal cis-to-trans isomerisation process has been studied for a series of para-, ortho- and polyhydroxy-substituted azobenzenes in different solvents. The kinetics of the thermal back reaction for the p-hydroxy-substituted azobenzenes depend strongly on the nature of the solvent used, with relaxation times ranging from 200-300 milliseconds in ethanol to half an hour in toluene. Otherwise, the process rate is mainly independent of the solvent nature for the ortho substituted analogues. Polyhydroxy-substituted azobenzenes show very much faster kinetics than the para- and ortho- monohydroxyazoderivatives. With relaxation times of 6-12 milliseconds in ethanol, they are optimal molecules for designing fast optical switching devices. All the hydroxyazoderivatives thermally isomerise from the metastable cis form to the thermodynamically stable trans isomer through a rotational mechanism.