Inorganic-Organic Hybrid Photomechanical Crystals Consisting of Diarylethenes and Cage Siloxanes

Photomechanical materials have received increasing attention because of their wide range of potential applications. This paper reports the design of photoresponsive inorganic-organic hybrid molecules consisting of diarylethene and polyhedral oligomeric silsesquioxane (POSS) linked by amide bonds. The POSS modification of diarylethene enhanced the conversion ratio from the open- to the closed-ring isomers upon UV irradiation in a solution. When isobutyl-substituted POSSs were introduced, hydrogen-bonded molecular crystals with a long needle-like morphology were obtained. Reversible photochromic responses and photoinduced macroscopic bending of these crystals upon ultraviolet (UV) and visible light (Vis) irradiations have been achieved. The high fatigue resistance of the diarylethene moiety combined with enhanced thermal stability endowed by the siloxane moiety is promising for practical applications in actuators and other smart devices.