Submolecular Observation of Photosensitive Macrocycles and Their Isomerization Effects on Host−Guest Network

• Published in: Journal of the American Chemical Society Vol. 131; no. 17; pp. 6174 - 6180
• Main Authors: Shen, Yong-Tao, Guan, Li, Zhu, Xiao-Yang, Zeng, Qing-Dao, Wang, Chen
• Format: Journal Article
• Language: English
• Published: United States American Chemical Society 06.05.2009
• ISSN: 0002-7863; 1520-5126
• 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.