Luminescence of porphyrins and metalloporphyrins VIII: luminescence and hydrogen photogeneration from porphyrin conjugate diacids

Abstract

Porphyrin conjugate diacids are formed by addition of two extra protons to the pyrrole nitrogen atoms of the porphyrin ring and the compounds derived from tetraphenylporphine absorb strongly at wavelengths above 600 nm. The absorption and fluorescence properties depend on inductive effects of any substituents on the phenyl rings. No phosphorescence was detected although the diacids show relatively long-lived triplet states at room temperature. The diacids photosensitize the dissociation of formic acid into hydrogen and CO 2 although the rates of hydrogen formation are slow.