Pulsed irradiation of water-soluble porphyrins

Abstract

Nanosecond laser flash photolysis and pulse radiolysis have been used to characterise the excited states and radicals of meso-tetraphenylporphyrin tetrasulphonic acid as the tetrasodium salt (Na₄TPPS) and of meso-tetra-N-methylpyridylporphyrin as the tetra-p-toluenesulphonate (TMPyrP). After 347 nm irradiation, aqueous Na₄TPPS forms triplet states (ϕ_T= 0.76) and photoionises monophotonically (Φ_I= 0.029), while TMPyrP forms only triplets (Φ_T= 0.92) and does not photoionise. The difference and corrected spectra of the triplet states and the semi-oxidised and semi-reduced radicals of these molecules have been obtained.