Photochemically Reversible and Thermally Stable Axially Chiral Diarylethene Switches

A series of dithienylcyclopentenes containing axially chiral 1,1'-binaphthyl units were successfully synthesized by a Suzuki-Miyaura protocol. All these compounds exhibited photochemically reversible isomerization with thermal stability in both organic solvent and a liquid crystal (LC) host. When doping into an achiral LC host, some of them exhibited very high helical twisting powers. Reversible reflection wavelength tuning in the visible region and LC phase switching between nematic and cholesteric upon light irradiation were demonstrated.