Preparation and properties of sol-gel thin films with porphins

Amorphous silica films doped with porphine derivatives were prepared by the sol-gel method with a dip-coating technique. The films doped with tetrakis(1-methylpyridinium-4-yl)-porphine p-toluenesulfonate (TMPyP) or tetraphenylporphine tetrasulfonic acid (TPPS) were heat treated at various temperatures, and the changes in the optical spectra were observed as a function of temperature. It was found that the porphins in the films could be heat treated up to ~200°C. A photochemical hole was formed in the lowest transition of the Q band of TMPyP in the silica film at ~20 K.