Synthesis and photochromic properties of imidazole-based diarylethenes

A series of symmetrical imidazole- and N-methylated imidazole-based diarylethenes were synthesized, and the structures have been well characterized by NMR spectroscopy and mass spectrometry. Their photochromism were investigated upon UV/vis light irradiation in DMF solution. A significant red-shift of UV absorption was observed after irradiation with UV light when substituents on the benzene ring (such as methoxyl group) were introduced. But N-methylation on the two imidazole rings will result in a blue-shift of UV absorption. The photophysical properties can be adjusted by changing the substituents, which provides a new strategy for the design of diarylethenes with excellent properties.