Synthesis and Properties of Photochromic Diarylethenes Bearing Thiazole Moiety

Four new diarylethene derivatives based on thiophene or thiazole moieties were designed and synthesized, and the structures of compounds 4a and 5a were determined by single-X-ray diffraction analysis. All of these compounds showed reversible photochromic reactions and notable fluorescence photo-switches in solution. Furthermore, diarylethenes 4a and 5a also showed good photochromism in single crystal phase. The electron-donating and electron-withdrawing substituents play the same role in the photochromic process: red-shifted absorption and fluorescence ( 1a and 2a compared with 3a ). The fluorescent modulation efficiencies of asymmetrical diarylethenes 4 and 5 were significantly enhanced compared with the similar dithienylethenes, and the fatigue resistance of 5 was much better than 4 , which showed that the diarylethene bearing electron-withdrawing group could improve its fatigue resistance.