Correlation between the molecular structure and transcis isomerization characteristics of azobenzenes

作     者：HAN Mina HONDA Takumu 

作者机构：Department of Chemistry and Department of Electronic ChemistryTokyo Institute of Technology 

出 版 物：《Science China Chemistry》 (中国科学（化学英文版）)

年 卷 期：2011年第54卷第12期

页      面：1955-1961页

核心收录：

学科分类：081704[工学-应用化学] 07[理学] 08[工学] 0817[工学-化学工程与技术] 070303[理学-有机化学] 0703[理学-化学] 

基　　金：supported by the Global COE Program from the Ministry of Education Culture Sports Science and Technology of Japanese Government 

主　　题：azobenzene isomerization lifetime of cis form molecular structure 

摘      要：Photochemical and thermal isomerization of various azobenzenes was systematically investigated to understand the correlation between the molecular structure and trans → cis isomerization characteristics of azobenzenes. A blue shift in π-π absorption band of ortho-alkylated azobenzenes （1o and 2o） was observed together with a reduction in molar extinction coefficient （e） in comparison with both meta-alkylated azobenzenes （4m and 5m） and 7p lacking the meta and ortho substituents. For orthoalkylated azobenzene, photochemical trans-to-cis isomerization and thermal back cis-to-trans isomerization in solution oc- curred slowly when compared with 4m, 5m and 7p. The half-life time of the cis form of 20 was found to be 380 h, which is about 8-50 times longer than those of comparable 4m, 5m （43-13 h） and 7p （7 h）. Furthermore, comparison of the molecular structure and isomerization characteristics of azobenzene thiol （20 and 5m） self-assembled monolayers on flat gold surfaces indicates that the trans-to-cis photoconversion in monolayer systems is influenced by steric hindrance and strong intermoleculax interaction between azobenzene units.