Influence of polarity of the peripheral substituents of porphyrin molecules on the photocatalytic activity of Cu(ii) porphyrin modified TiO2 composites

Two novel porphyrins, 5,10,15-tri-phenyl-20-[4-(2-(4-formoxyl) phenoxy)ethoxy]phenyl porphyrin and 5,10,15-tri-phenyl-20-[4-(2-(4-hydroxyimino) phenoxy)ethoxy]phenyl porphyrin, and their corresponding copper(II) complexes were synthesized and spectroscopically characterized. The Cu(II) porphyrin–TiO2 composites were also prepared and characterized. The photoactivity of the composites was investigated by carrying out the degradation of 4-nitrophenol (4-NP) in aqueous solution under UV-visible light. It was found that the photoactivity of Cu(II) porphyrin–TiO2 composites was evidently influenced by the interaction between porphyrin molecules and hydroxyls anchored on the TiO2. Furthermore, the photoactivity of Cu(II) porphyrin–TiO2 composites was also affected by dispersion of composites in 4-NP solution.