The triplet excited state changes of amphiphilic porphyrins with different side-chain length in AOT reverse micelles

Two amphiphilic porphyrins terminated with carboxyl were studied in AOT/iso-octane/water reverse micelles, intending to mimic the relationship between microenvironments in organism and the amphiphilic properties of porphyrins for photodynamic therapy (PDT) drugs. The quenching of porphyrins by methyl viologen chloride and the laser flash photolysis experiments show that the longer side-chain length would promote the firm embedding of porphyrin molecules in the interfacial region of reverse micelles. Such an embedding may shift porphyrins from aggregated to monomeric form in reverse micelles and, accordingly, the slower excited state decay may increase the efficiency of the photosensitizer in PDT. The effect of amphiphilic properties on the status of porphyrins in microenvironments provides a light on the synthesis of other amphiphilic porphyrins for PDT drugs.