THE INFLUENCE OF D(2)O ON THE PHOTOPHYSICAL PROPERTIES OF MESO-TETRA(4-SULPHONATOPHENYL) PORPHINE, PHOTOSAN-III AND TETRASULFONATED ALUMINUM AND ZINC PHTHALOCYANINES

Kinetic spectroscopy was employed to study the effect of D2O on the lifetime of triplet states and bimolecular quenching constants of meso-tetra(4-sulphonatophenyl) porphine, Photosan III and tetrasulphonated aluminium and zinc phthalocyanines by oxygen. The natural lifetime of the triplet states of all the compounds increases in alkaline D2O medium, while their reactivity with oxygen remains similar as in H2O solution. The dependence of the rate constant for deactivation of triplet states on the D2O concentration is linear. The increase in the lifetime of the triplet states of the given species in D2O is apparently not a consequence the lower self-quenching rate caused by the different viscosity of the two solvents, but rather by the different vibrational coupling between the terminal sulpho-groups of the sensitizer and the solvent shell or isotopic substitution of a hydrogen atom by deuterium in the given species.