Synthesis of Novel Thermally Irreversible Photochromic 1-Aryl-1,3-butadiene Derivatives

A new thermally irreversible photochromic compound, 3,3,4,4,5,5-hexafluoro-1-(1-isopropylidene-1-phenylmethyl)-2-(2,4,5-trimethyl-3-thienyl)cyclopentene 3O, was synthesized and its photochromic properties were examined. It showed thermally irreversible photochromism. While 3O is colorless, it turned yellow ((lambda)max 445 nm) upon the irradiation of 313-nm light, caused by the generation of 3C as the result of photochemical 6(pi)-electrocyclization. It returned to the initial colorless state by 405-nm light irradiation. The coloration and decoloration quantum yields with 313-nm light were 0.43 and 0.14, respectively, and the decoloration quantum yield with 405-nm light was 0.16. The colored form 3C in a PMMA film did not fade when stored at 80 °C for more than one month, and the fatigue resistivity in the PMMA film for iterative irradiation was excellent.