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Martin Jarenmark

Martin Jarenmark

Research engineer

Martin Jarenmark

A Heterobimetallic FeIIIMnII Complex of an Unsymmetrical Dinucleating Ligand: A Structural and Functional Model Complex for the Active Site of Purple Acid Phosphatase of Sweet Potato

Author

  • Biswanath Das
  • Henrik Daver
  • Amrendra Singh
  • Reena Singh
  • Matti Haukka
  • Serhiy Demeshko
  • Franc Meyer
  • George Lisensky
  • Martin Jarenmark
  • Fahmi Himo
  • Ebbe Nordlander
Show all

Summary, in English

The heterodinuclear mixed-valence complex [FeMn(ICIMP)(OAc)(2)Cl] (1) {H2ICIMP = 2-(N-carboxylmethyl)-[N-(N-methylimidazolyl-2-methyl)aminomethyl]-[6-(N-isopropylmethyl)-[N-(N-methylimidazolyl-2-methyl)]aminomethyl-4-methylphenol], an unsymmetrical N4O2 donor ligand} has been synthesized and fully characterized by several spectroscopic techniques as well as by X-ray crystallography. The crystal structure of the complex reveals that both metal centers in 1 are six-coordinate with the chloride ion occupying the sixth coordination site of the Mn-II ion. The phenoxide moiety of the ICIMP ligand and both acetate ligands bridge the two metal ions of the complex. Mossbauer spectroscopy shows that the iron ion in 1 is high-spin Fe-III. Two quasi-reversible redox reactions for the complex, attributed to the (FeMnII)-Mn-III/(FeMnII)-Mn-II (at -0.67 V versus Fc/Fc(+)) and (FeMnII)-Mn-III/(FeMnIII)-Mn-III (at 0.84 V), were observed by means of cyclic voltammetry. Complex 1, with an Fe-III-Mn-II distance of 3.58 angstrom, may serve as a model for the mixed-valence oxidation state of purple acid phosphatase from sweet potato. The capability of the complex to effect organophosphate hydrolysis (phosphatase activity) has been investigated at different pH levels (5.5-11) by using bis(2,4-dinitrophenyl)phosphate (BDNPP) as the substrate. Density functional theory calculations indicate that the substrate coordinates to the Mn-II ion. In the transition state, a hydroxide ion that bridges the two metal ions becomes terminally coordinated to the Fe-III ion and acts as a nucleophile, attacking the phosphorus center of BDNPP with the concomitant dissociation of the leaving group.

Department/s

  • Chemical Physics

Publishing year

2014

Language

English

Pages

2204-2212

Publication/Series

European Journal of Inorganic Chemistry

Volume

2014

Issue

13

Document type

Journal article

Publisher

John Wiley & Sons Inc.

Topic

  • Atom and Molecular Physics and Optics

Keywords

  • Metalloenzymes
  • Mixed-valent compounds
  • Moessbauer spectroscopy
  • Density
  • functional calculations
  • Transition states
  • Hydrolysis

Status

Published

ISBN/ISSN/Other

  • ISSN: 1099-0682