ABSORPTION AND RAMAN-SCATTERING BY AGGREGATED MESO-TETRAKIS(P-SULFONATOPHENYL)PORPHINE

In the present paper, we combine absorption and Raman scattering measu rements to characterize aggregated TSPP in homogeneous aqueous solutio n. We deduce that aggregation evolves through the formation of TSPP di acid and that the diacid is the repeating unit in the aggregate. We fu rther conclude that vibrations of adjacent molecules are perturbed in a fashion that is consistent with the pyrrolic ring in the porphinato macrocycle being ruffled, and that two aggregate arrangements occur: s pecifically, linear J- and H-type aggregate structures are proposed wh ich are commonly defined in molecular exciton theory. Aggregation enha ncement is advanced as a viable mechanism to explain enhanced Raman sc attering, especially for homogeneous, aqueous phase TSPP, where SERS i s not applicable. Vibrational band assignments are also made.