Shen Yong-Tao, Guan Li, Zhu Xiao-Yang, Zeng Qing-Dao, Wang Chen
National Center for Nanoscience and Technology (NCNST), Beijing 100190, PR China.
J Am Chem Soc. 2009 May 6;131(17):6174-80. doi: 10.1021/ja808434n.
The macrocyclic compounds consisting of photosensitive units as parts of the frame have been extensively studied to mimic photoregulated functions in nature. In this paper, controlled assembly of well-ordered arrays of photosensitive macrocyclic rectangles is demonstrated by using a host-guest molecular template. 4NN-Macrocycle molecules are observed to photoisomerize from trans-trans-trans-trans (t,t,t,t) to a range of isomers including trans-trans-trans-cis (t,t,t,c) and trans-cis-trans-cis (t,c,t,c) isomers after irradiation of UV light. The photoisomers are also observed to affect the guest-host network characteristic appreciably. In the STM observations we can distinguish three (t,t,t,t) conformational isomers, three (t,t,t,c) conformational isomers, and one (t,c,t,c) isomer, which self-assemble into different adlayers with TCDB on a HOPG surface. This study provides a facile approach to study the photoisomerization processes of the azobenzene groups and the conformational photoisomers.
由光敏单元作为框架组成部分的大环化合物已被广泛研究，以模拟自然界中的光调节功能。本文通过使用主客体分子模板展示了光敏大环矩形有序阵列的可控组装。观察到4NN-大环分子在紫外光照射后从反-反-反-反（t,t,t,t）光异构化为一系列异构体，包括反-反-反-顺（t,t,t,c）和顺-反-顺-反（t,c,t,c）异构体。还观察到光异构体对客体-主体网络特性有明显影响。在扫描隧道显微镜（STM）观察中，我们可以区分三种（t,t,t,t）构象异构体、三种（t,t,t,c）构象异构体和一种（t,c,t,c）异构体，它们在HOPG表面与TCDB自组装成不同的吸附层。这项研究提供了一种简便的方法来研究偶氮苯基团的光异构化过程和构象光异构体。
