4, 5-bis(5-chloro-2-methylthiophen-3-yl)-1, 2-diphenyl-1H-imidazole (L) is synthesized and characterized by 1H NMR, 13C NMR and elemental analysis. The effects of acid on the absorption spectra, fluorescence spectra and thermal stability of L are investigated. The results show that the acid effect on the absorption spectra of L is very little, but the fluorescence spectra and thermal stability of L can be effectively regulated by the acid. In addition, L shows good photochromism before and after the protonation, as well as the distinctive "on to on" fluorescence characteristic.

photochromism  /  diarylethene  /  acid effect  /  fluorescence  /  thermal stability