Synthesis and aggregation behavior of a novel water-soluble porphyrin platinum(II) terpyridine complex

Abstract

A new water soluble tetranuclear platinum(II) porphyrin complex cation has been synthesized through the coordination of four [ Pt (2,2′:6′,2″-terpyridine)] moieties to the pyridyl groups of 5,10,15,20-tetrakis(4-pyridyl)-21H,23H-porphine (TPyP). The porphyrin derivative has been fully characterized by a combination of spectroscopic techniques. The high positive charge of the complex cation (8+) inhibits the aggregation in aqueous solution at low concentrations. By increasing the ionic strength, the electrostatic repulsion is screened leading to the formation of large unstable aggregates. The formation of microsized globular objects still emissive on the solid state is easily achieved by simple evaporation from diluted solutions. The solubilization of the complex in anionic aqueous surfactant solutions (sodium dodecyl sulfate, SDS) has revealed the inclusion of the complex ion in the hydrophobic region of the micelles as a monomeric species. Kinetics of Cu(II) insertion into the free-base tetranuclear Pt(II) porphyrin complex have been carried out in micellar media and the rate constants have been determinated.