Cation-recognized photosensitization in E-Z isomerization of 1,2-dichloroethylene by crowned benzophenones.

Abstract

Photosensitized isomerization of 1,2-dichloroethylene with 15- and 18-membered-ring crowned benzophenones (1a and 1b) as triplet sensitizers resulted in the cation-dependent increase in the Z/E isomer ratios up to ca. 10 by addition of alkali and alkaline earth metal ions in comparison with the metal-free reactions (Z/E = 1.5-2.1). The highest Z/E values were attained for 1a with Li+ (2.9) and Mg2+ (5.3), and for 1b with Na+ (8.2) and Ca2+ (9.8), respectively, among each family of alkali and alkaline earth metal ions. It was found that the cation recognized sensitization brought about the change of the inherent triplet energy ET as well as the PhiE/Phiz ratio to raise the Z/E isomer ratio of 1,2-dichloroethylene.

• Authors: Ken Kokubo, Hidenobu Kakimoto, Takumi Oshima
• Journal: Journal of the American Chemical Society (J Am Chem Soc) Vol. 124 Issue 23 Pg. 6548-9 (Jun 12 2002) ISSN: 0002-7863 [Print] United States
• PMID: 12047171 (Publication Type: Journal Article)