Preparation and characterization of tetra(4-pyridyl)porphyrinatomanganese(III) cation supported covalently on poly(siloxane)

Abstract

Tetra(4-pyridyl)porphyrinatomanganese(III), [MnIII(TPyP)]+, has been covalently bonded to the surface of a chlorinated crosslinked poly(siloxane) which contains the immobilized chloropropyl group, -CH2CH2CH2Cl. The metalloporphyrin complex was found to react with the immobilized ligand via a quaternization reaction of the 4-pyridine N-atom. The porphyrin binding involves a chemical process rather than physical adsorption. There is evidence that two porphyrins species coexist, both bonded to the surface, one being [MnIII(TPyP)]+ and the other (H2TPyP), both in the quaternary salt forms, when the quaternization reaction is carried out at higher temperature (150 °C). At moderate reaction temperatures (70–80 °C) the quaternization reaction resulted in only one species, supported [MnIII(TPyP)]+, as evident from electronic spectra of the solid. Also, visible absorption spectra taken of the solution remaining after the quaternization reaction showed no demetallated porphyrm. Solid state electronic absorption, dispersive IR and FT-IR spectra have been used for confirmation.