Determination of fluorescence yields, singlet lifetimes and singlet oxygen yields of water-insoluble porphyrins and metalloporphyrins in organic solvents and in aqueous media

Article abstract of DOI:10.1111/j.1751-1097.1999.tb03322.x

Fluorescence quantum yields and singlet lifetimes for a wide range of hydrophilic to hydrophobic porphyrins and metalloporphyrins have been determined in toluene, methanol or acetone. Photosensitized singlet oxygen yields have been determined in the same solvents. For some porphyrins, the same quantities were determined in an aqueous medium, through use of an amphiphilic polymer to solubilize the porphyrin sensitizer and target molecule, 1,3-diphenylisobenzofuran. Because rate constants for the deactivation of singlet oxygen (k_d) and for its reaction with a target molecule (k_a) are unknown in such aqueous polymer systems, a new method was developed for evaluating yields of singlet oxygen formation that also provides a value for the ratio k_dk_a A variation observed in quantum yield of singlet oxygen production for the aqueous polymer system with variation in initial concentration of the target molecule is discussed.