Abstract
Spirooxazines (SOs) exhibit the well-known photochromic reaction of photoinduced interconversion between the original colorless form and the colored merocyanine (MC) form. The MC easily coordinates to specific metal ions (e.g., Zn2+) in solvents and forms a fluorescent chelate complex. It is difficult to dissociate the complex in solvents because it is stable to heat and visible light. The control of the interaction between the SO molecule and metal ion is required for the reversible photochromic reaction. For example, MC forms a reversible complex with metal bonding to oxide networks such as silica gel and it is dissociated by visible irradiation because the MC is weakly coordinated to the metal ion. Such photochromic reaction can be control in the sol-gel matrix by organic modification of the silicon due to increasing the pore volume changing the polarity. The elucidation of the formation and dissociation of such metal chelates leads to create novel photofunctional materials.
