Synthesis, Photochromism Properties of a Hybrid Diarylethene with Biphenyl

An unsymmetrical diarylethene derivative bearing both phenyl and thiophene moieties, in which a phenyl group was substituted at the par a-positions of the terminal phenyl ring, was synthesized. At the same time, its photochromic properties and fluorescence switch were investigated in detail. The results showed that this compound exhibited reversible photochromism, undergoing reversible cyclization and cycloreversion reactions upon alternating irradiation with UV and visible light both in solution and in PMMA film, and its absorption maxima were observed at 590 mn in hexane and at 571 nm in PMMA amorphous film, respectively, upon irradiation with 297 nm UV light. The fluorescence intensity of diarylethene decreased dramatically along with the photochromism from open-ring isomer to closed-ring isomer upon irradiation with 297 nm UV light in PMMA and in hexane. In hexane solution, the open-ring isomer of the diarylethene 1 exhibited relatively strong fluorescence at 372 nm when excited at 330 nm.