Angewandte Chemie International Edition
© WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
Cover Picture: Absolute Asymmetric Photocyclization of a Photochromic Diarylethene Derivative in Single Crystals (Angew. Chem. Int. Ed. 14/2003)
Absolute Asymmetric Photochromism in chiral crystals has enormous potential. The cover picture shows this phenomenon for 1,2-bis(2-methyl-5-(3-formylphenyl)-3-thienyl)perfluorocyclopentene, which has no chiral resources, but forms chiral crystals. Upon UV irradiation the diarylethene unit undergoes the photochromic reaction both in the single crystals and in solution, and each chiral crystal gives one enantiomer. The photocyclization/cycloreversion cycle can be repeated by using UV and visible light alternately. Details of the study are reported by M. Irie et al. on page 1636 ff.