SYNTHESIS AND CHARACTERIZATION OF COBALT PHTHALOCYANINES COVALENTLY ATTACHED TO SILICA

We have synthesized cobalt phthalocyanines (PcCo, 4-t-Bu4-PcCO) covalently attached to a silica surface. The formation of the sulfonamide linkage was used as a mode of attachment. The resulting catalysts were examined in the reaction of autoxidation of cysteine. The catalytic properties of the silica-attached PcCo are compared to those of PcCo in crystalline, soluble and adsorbed states. It was shown that the method of covalent attachment yields highly active catalysts which are stable under the experimental conditions. The degree of PcCo dispersion in these catalysts was found to depend on the hydroxylated structure of SiO2, the structure of the phthalocyanine molecule, and the concentration of phthalocyanine in the sample. The structural parameters of the silica-attached phthalocyanine layers in the samples studied have been estimated by assuming a correlation between the catalytic activity data and the degree of PcCo dispersion.