Fluorescence modulation in photochromic amorphous diarylethenes

1,2-Bis(2-methyl-1-benzothiopfken-3-yl)perfluorocyclopentene derivatives having 2,4-diphenylphenyl substituents at 6 and 6' positions of the benzothiophene rings showed reversible photocyclization reactions and fluorescence spectral changes upon alternate irradiation with UV and visible light in the amorphous state. Both di- and mono-substituted derivatives, compounds 1a and 2a, formed stable amorphous state at room temperature and their glass transition temperatures were 127,and 88 degreesC, respectively. The closed-ring isomer of the di-substituted derivative 1b exhibited red fluorescence at 650 nm. (C) 2002 Elsevier Science B.V. All rights reserved.