Synthesis and Properties of Photochromic Diarylethene Derivatives Bearing Benzofuran and Isoxazole Units

A new unsymmetrical photochromic diarylethene, 1(2-ethyl-3-benzofuranyl)-2(3,5-dimethyl-4-isoxazolyl) perfluorocyclopentene(1a)were synthesized, and its properties, such as photochromism and fluorescence properties in solution as well as in poly-methylmethacrylate (PMMA) amorphous films, were investigated in detail. The results showed that this compound had good thermal stability and exhibited reversible photochromism, changing from colorless to yellow after irradiation with UV light both in solution and in PMMA amorphous film. The open-ring isomer of the diarylethene 1a exhibited relatively strong fluorescence at 401 nm in hexane solution (2 × 10^-5 mol/L) when excited at 307 nm and 408 nm in PMMA amorphous film when excited at 282 nm. The fluorescence intensity decreased along with the photochromism upon irradiation with 297 nm light.