Enantiodifferentiating photoisomerization of cyclooctene included and sensitized by aroyl-β-cyclodextrins: A critical enantioselectivity control by substituents

Runhua Lu, Cheng Yang, Yujuan Cao, Linhui Tong, Wei Jiao, Takehiko Wada, Zhizhong Wang, Tadashi Mori, Yoshihisa Inoue

Research output: Contribution to journalArticlepeer-review

48 Citations (Scopus)

Abstract

(Chemical Equation Presented) A series of 6-O-benzoyl-β-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 (KS) of the modified β-CDs with 1Z in aqueous methanol solutions were highly sensitive to the substituent(s) introduced to the benzoate moiety, and the log KS 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.

Original languageEnglish
Pages (from-to)7695-7701
Number of pages7
JournalJournal of Organic Chemistry
Volume73
Issue number19
DOIs
Publication statusPublished - 2008 Oct 3
Externally publishedYes

ASJC Scopus subject areas

  • Organic Chemistry

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