Photochemical Liquid-Solid Transitions in Multi-dye Compounds

We report the synthesis of liquid crystalline materials, which repeatedly liquefied and solidified when irradiated with ultraviolet (UV) and visible light at room temperature. The materials are the derivatives of the sugar alcohols, D-mannitol, D-sorbitol, and allitol, in which all hydroxyl groups were substituted with multi-mesogenic azobenzenes. The thermal phase transition behavior and stability of the liquid crystal phase were changed according to the sugar alcohols, but photochemical phase transition behaviors were not different. In addition, when applied as an adhesive layer to glass substrates, the materials exhibited changes in the adhesion force when irradiated with light.