Photomechanical Bending of Molecular Crystals

摘要: Creation of mechanical crystals has been the focus my study on solid-­state photoreactions molecular for 20 years. Our search photomechanical crystals, based operating principle that should bend via reversible photochromic reactions, found typical composed azobenzene, salicylideneaniline, and furylfulgide upon photoirradiation. When plate-like microcrystals trans-4-(dimethylamino)azobenzene were irradiated at 365 nm, quickly bent away from light. Thirty seconds after light was extinguished, crystal returned to its initial flat shape. To our knowledge, trans–cis photoisomerization azobenzene chromophores not observed in crystalline state, but occurrence near surface confirmed. Plate-like a salicylideneaniline compound could be repeatedly straightened over 200 cycles by alternately irradiating with UV visible light, respectively. Microcrystals exhibited same behavior. X-ray crystallographic analyses before photoirradiation showed mechanism bending involved molecular-level shape changes induced macroscale motion. Synthetic machines convert photoenergy directly into work through structural are attractive both basic research many potential applications. These will contribute advancement machinery.