New photochromic diarylethenes with a pyrimidine moiety

A novel class of photochromic diarylethene derivatives based on the hybrid skeleton of six-membered pyrimidine and five-membered thiophene moieties has been firstly synthesized. The substituent effects on their properties, including photochromism, fatigue resistance, and fluorescence, have been systematically investigated. All these diarylethenes showed significant photochromism and notable fluorescence switching properties in both solution and poly(methylmethacrylate) films. The electron-donating substituent enhanced their cyclization quantum yield, fatigue resistance, and fluorescence quantum yield, whereas electron-withdrawing group exhibited contrary effects.