Enantiodifferentiating photoisomerization of cyclooctene included and sensitized by aroyl-beta-cyclodextrins: a critical enantioselectivity control by substituents |
| |
Authors: | Lu Runhua Yang Cheng Cao Yujuan Tong Linhui Jiao Wei Wada Takehiko Wang Zhizhong Mori Tadashi Inoue Yoshihisa |
| |
Institution: | Department of Applied Chemistry, College of Sciences, China Agricultural University, Beijing 100094, China. lurh@cib.ac.cn |
| |
Abstract: | A series of 6-O-benzoyl-beta-cyclodextrins (CDs) with methyl, methoxy, methoxycarbonyl, and bromo substituent(s) at the ortho-, meta-, and/or para-position(s) were synthesized as chiral sensitizing hosts for the use in supramolecular enantiodifferentiating photoisomerization of (Z)-cyclooctene (1Z) to its chiral (E)-isomer (1E). The complex stability constants (K(S)) of the modified beta-CDs with 1Z in aqueous methanol solutions were highly sensitive to the substituent(s) introduced to the benzoate moiety, and the log K(S) values decreased linearly with slightly different slopes with increasing methanol content. The enantiomeric excess (ee) of 1E obtained upon photosensitization with these hosts was a critical function of the size and position of the substituent, varying from almost zero to 46% ee. This indicates that even an apparently small structural difference between methyl and methoxy can critically affect the enantiodifferentiating photoisomerization of a guest included in the chiral cavity, probably through manipulation of both the orientation of ground-state 1Z and the subsequent rotational relaxation of excited 1Z inside the chiral cavity. |
| |
Keywords: | |
本文献已被 PubMed 等数据库收录! |
|