One-pot synthesis of β-carboxy tetra aryl porphyrins: potential applications to dye-sensitized solar cells

A facile one-pot conversion of 2-formyl-5,10,15,20-tetra aryl-substituted porphyrins and their zinc derivatives to the corresponding 2-carboxy-5,10,15,20-tetra aryl-substituted porphyrins was achieved for the first time by using hydroxylamine hydrochloride and phthalic anhydride. All these substituted carboxy porphyrins were completely characterized by using mass, CHN analysis, 1H NMR, UV–vis, Fluorescence spectroscopies, and cyclic voltammetry. Both the absorption maxima and emission maxima were red shifted by 5–7 nm. The LUMO of these porphyrins are above the TiO2 conduction band and HOMO was below the redox electrolytes. These carboxy porphyrins are potential applications as sensitizers to dye-sensitized solar cell.