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

Fluorescence quantum yields and singlet lifetimes for a wide range of hydro philic to hydrophobic porphyrins and metalloporphyrins have been determined in toluene, methanol or acetone, Photosensitized singlet oxygen yields hav e been determined in the same solvents. For some porphyrins, the same quant ities were determined in an aqueous medium, through use of an amphiphilic p olymer to solubilize the porphyrin sensitizer and target molecule, 1,3-diph enylisobenzofuran. Because rate constants for the deactivation of singlet o xygen (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 rati o k(d)/k(a). A variation observed in quantum yield of singlet oxygen produc tion for the aqueous polymer system with variation in initial concentration of the target molecule is discussed.