Silica-Based Inorganic Materials Manipulated by Light

Silicon oxides are one of the most frequently employed components for inorganic-organic hybrid materials. We have also been studying the creation of new hybrid materials and their functions, especially using photo-responsive organic substituents. A silsesquioxane compound with eight coumarin substituents produces reversible photo crosslinking polymers by UV irradiation. The coumarin modification at the outlets of mesopores of mesoporous silica fabricates a photo responsive molecular gate of their mesopores, which achieves drug release triggered by UV light. The continuous photo isomerization of azobenzene between its trans and cis isomers acts as a molecular "broom" to promote the release of many nearby molecules loaded into the pore voids of mesoporous silica. This phenomenon can be applied as well to control the effluent rate of developing solvents of column chromatography. These authors' achievements reveal the potential of inorganic-organic hybrid materials with photo responsive functional groups to generate new functional materials.