Syntheses and Properties of a Novel Unsymmetrical Photochromic Diarylethene with a Cyano Group Based on Benzfuran

An unsymmetrical diarylethene derivative bearing both benzfuran and thiophene moieties, in which a Cyano group was substituted at the ortho-positions of the terminal phenyl ring,was synthesized. 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. The fluorescence intensity of diarylethene decreased dramatically along with the photochromism from open-ring isomer to closed-ring isomer upon irradiation with 297 nm light in PMMA. In hexane solution, the open-ring isomer of the diarylethene 1 exhibited relatively strong fluorescence at 411 nm when excited at 400 nm.