The effect of a "push-pull" structure on the turn-on fluorescence of photochromic thio-ketone type diarylethenes.

a series of diarylethene compounds with a thiophene bridging unit have been synthesized to investigate the relationship between molecular structure and photochromic properties. In particular, the fluorescence properties related to compound 1 were investigated. The results showed that a six-membered ring carrying an electron-donating sulfur atom and an electron-withdrawing carbonyl group is necessary to form a "push-pull" system for the fluorescence of 1.