Charge interactions of water soluble oxo-titanium(IV) porphyrins with CTAC and SDS micelles

The interactions of anionic oxo-titanium (IV) meso-tetrakis(4-sulfonatophenyl)porphyrin and cationic oxo-titanium(IV) meso-tetrakis(1-methylpyridium-4-yl)porphyrin with anionic and cationic micelles were examined by Raman spectroscopy and transient absorption spectroscopy. The Raman bands of OTiIV porphyrins in the presence of surfactants with same charge were similar to those observed in a pure water solution. The characteristic Raman band was observed at 915 cm−1, which was assigned to the OTi stretching mode of the 6-coordinated complex, OTi(H2O) porphyrins. On the other hand, in the presence of oppositely charged surfactants, a markedly up-shifted Raman band was observed at 945 cm−1, which was assigned to the OTi stretching mode of a 5-coordinated complex, OTi porphyrins. OTi porphyrins interact with oppositely charged surfactant micelles by losing the sixth axial ligand (H2O). The 5-coordinate complexes showed a shorter lifetime of the exited triplet state due to the lower lying quenching state.