The synthesis of novel photochromic diarylethenes bearing a biphenyl moiety and the effects of substitution on their properties

A new class of diarylethene bearing a biphenyl moiety was synthesized and the effects of substitution on photochromism, fluorescence and electrochemical character, were investigated. Under alternating irradiation with UV and visible light, the compounds exhibited good photochromism and functioned as fluorescent photoswitches both in solution and in PMMA film. Electron-donating substituents shifted the λmax of the diarylethenes to longer wavelengths and decreased their cyclization quantum yield, while electron-withdrawing substituents greatly increased both cyclization and cycloreversion quantum yield. In addition, cyclic voltammetry revealed that the substituents had a significant effect on the electrochemical behaviour of the diarylethene derivatives.