Synthesis, spectral, electrochemical and flash photolysis studies of Fe(II), Ni(II) tetrapyridylporphyrins coordinated at the periphery with chromium(III) phenanthroline complexes

Abstract

[FeTPyP(Crphen2Cl)4][PF6]8 and [NiTPyP(Crphen2Cl)2][PF6]8, where TPyP=5,10,15,20-tetra-(4-pyridyl)porphyrin and phen=1,10-phenanthroline, preparations are communicated. The complexes were characterized by UV–Vis spectroscopy, cyclic voltammetry, UV–Vis spectroelectrochemistry, elemental analysis, FT-IR, and MALDI-TOF mass spectrometry. Their photochemical reactions were investigated with the flash photolysis technique. The complexes exhibit a rich electrochemistry which includes a cathodic quasireversible process, i.e., the Cr(III)/Cr(II) couple, and two cathodic processes consistent in the sequential transfer of two electrons to the metalloporphyrins center. Porphyrin-centered excited states are generated in the flash irradiation (λexc=351nm) of either complex. These states are converted to other excited states or intermediates. The intermediates react with oxidants, Ru(NH3)63+, and reductants, I−, TEOA, and alcohols. Charge separated intermediates or excited states with LMCT character account for the photoreactions.