Photoacoustic Measurements of Porphyrin Triplet-State Quantum Yields and Singlet-Oxygen Efficiencies

Abstract

Photoacoustic calorimetry and luminescence techniques were used to measure singlet oxygen quantum yields (ΦΔ) of selected 5,10,15,20-tetrakis(aryl)porphyrins and of the novel chlorin shown. The use of validated photoacoustic references removes some inconsistencies existing in the literature. Excitation of halogenated porphyrins produces high yields of long-lived triplet states that efficiently transfer their energy to singlet oxygen. A route for red-absorbing, efficient singlet-oxygen photosensitisers is described.