Thermal stability of photochromic bis(trifluoromethyl thiazoyl)ethene derivatives

1, 2-Bis(2-phenyl-4-trifluoromethylthiazol-5-yl)hexafluoro-1-cyclopentene's synthesis allows a study of the thermal stability of the unique class of photochromic diarylethenes that it represents. The synthesis involves the reaction of lithiated 2-phenyl-4-(trifluoromethyl)thiazole with octafluorocyclopentene. Subsequent study shows that the introduction of the trifluoromethyl group results in a blue-shift in ultraviolet absorption and in an increased thermal stability of the ring-closed mesomer. In the open form, however, the TFM group seems to destabilize the thiazole ring.