Axial ligand effect on the catalytic activity of biomimetic Fe-porphyrin catalyst: an experimental and DFT study Articles uri icon

publication date

  • September 2016

start page

  • 768

end page

  • 777

volume

  • 344

international standard serial number (ISSN)

  • 0021-9517

electronic international standard serial number (EISSN)

  • 1090-2694

abstract

  • Electrostatic interactions occurring in the immediate environment of the metal center in native enzymes influence the charge distribution and electron donation ability, regulating activity. Herein, using an iron-porphyrin biomimetic complex, we have investigated the effect of the protonation state of the axial imidazole on the catalytic oxidation of pentachlorophenol. We show that the catalytic efficiency is drastically affected by the anionic state of the axial ligand. The chemical events occurring during the catalytic cycle were monitored by a detailed analytical study. EPR, UV-Vis and low temperature UV-Vis together with theoretical DFT and TD-DFT calculations provide evidence that deprotonation of the axial imidazole leads to increased electron donation ability to the central metal, enhancing the formation of ferryl species.

keywords

  • ferryl
    axial ligand
    additives
    co-catalyst
    chlorophenol
    chlorinated pollutants
    dft
    heme
    bond-cleavage
    iron tetrasulfophthalocyanine
    proximal ligand
    h2o2 oxidation
    pentachlorophenol
    complexes
    iron(iii)
    cytochrome-p-450
    dechlorination