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

Abstract

• Interaction of anionic and cationic porphyrin with micelles was studied by Raman and transient absorption spectroscopy. • O Ti porphyrins interact with oppositely charged surfactant micelles by losing the sixth axial ligand (H 2 O). • When associated with the same charged micelles, axial H 2 O ligand of O Ti porphyrins remains although they are in contact with each other. • The 5-coordinate complexes showed a shorter lifetime of the exited triplet state due to the lower lying quenching state. 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 O Ti IV 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 O Ti stretching mode of the 6-coordinated complex, O Ti (H 2 O) 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 O Ti stretching mode of a 5-coordinated complex, O Ti porphyrins. O Ti porphyrins interact with oppositely charged surfactant micelles by losing the sixth axial ligand (H 2 O). The 5-coordinate complexes showed a shorter lifetime of the exited triplet state due to the lower lying quenching state.