Quest for iron(III) isoporphyrins: Synthesis, characterization, reactivity and theoretical studies

Abstract

Detailed studies on iron(III) isoporphyrins, which are isoelectronic with iron(IV)-oxo porphyrin radical and very much reactive in nature are rare in the literature. Therefore, here we have reported the synthesis of a series of methoxy iron(III) isoporphyrins of tetraphenylporphyrin derivatives using chemical oxidants and characterized well with UV–Visible, IR, ESI-Mass, elemental analysis, thermal gravimetric studies (TGA), Powder X-Ray Diffraction studies and 1H NMR spectroscopy. The electrochemical studies were performed for the first time on such type iron(III) isoporphyrins. ESR and magnetic susceptibility studies supported the high-spin iron(III) nature of the isoporphyrins. For the first time, theoretical studies like geometry optimization, simulation of optical spectra, and energy calculations were performed on a methoxy isoporphyrin of simple [FeIII(TPP)Cl] (Iron(III) tetraphenyl porphyrin) using the density functional theory method to understand the typical electronic, redox and highly reactive nature of iron isoporphyrins. The theoretical calculations supported the strong absorptions at the near-IR region in electronic spectra, very reactive nature and typical redox behavior of iron(III) isoporphyrins.