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

Abstract

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-(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 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 (H2O). The 5-coordinate complexes showed a shorter lifetime of the exited triplet state due to the lower lying quenching state. (C) 2013 Elsevier B.V. All rights reserved.