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Characterization of the aqueous iron(III) chelation chemistry of a potential Trojan Horse antimicrobial agent: chelate structure, stability and pH dependent speciation.

Publication ,  Journal Article
Harrington, JM; Gootz, T; Flanagan, M; Lall, M; O'Donnell, J; Winton, J; Mueller, J; Crumbliss, AL
Published in: Biometals : an international journal on the role of metal ions in biology, biochemistry, and medicine
October 2012

The aqueous solution equilibria of a β-lactam antimicrobial agent containing a 3-hydroxy, 4-pyridinone group (L (PF)) binding to Fe(III) in aqueous solution has been characterized through spectrophotometric and potentiometric titrations. The metal-free ligand has four observable protonation constants, pK(a1) = 2.6, pK(a2) = 3.43, pK(a3) = 6.43, and pK(a4) = 9.62. L (PF) forms a 3:1 ligand:Fe(III) complex in aqueous solution through coordinate-covalent bond formation exclusively involving the bidentate hydroxypyridinone moiety. This 3:1 L (PF):Fe complex was found to have a stability constant of log β(130) = 33.46. A speciation diagram for the L (PF) system demonstrates that in the region of physiological pH the tris-(L (PF))Fe(III) complex, Fe(L(PF)) (3) (6-) , predominates. This complex exhibits two irreversible reduction waves in solution at -30 mV versus NHE, corresponding to a ligand-based reduction, and at -385 mV versus NHE, corresponding to an irreversible Fe(3+)/Fe(2+) reduction of the Fe(L(PF)) (3) (6-) complex.

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Published In

Biometals : an international journal on the role of metal ions in biology, biochemistry, and medicine

DOI

EISSN

1572-8773

ISSN

0966-0844

Publication Date

October 2012

Volume

25

Issue

5

Start / End Page

1023 / 1036

Related Subject Headings

  • beta-Lactams
  • Water
  • Spectrophotometry
  • Solutions
  • Potentiometry
  • Oxidation-Reduction
  • Molecular Structure
  • Ligands
  • Iron Chelating Agents
  • Hydrogen-Ion Concentration
 

Citation

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Harrington, J. M., Gootz, T., Flanagan, M., Lall, M., O’Donnell, J., Winton, J., … Crumbliss, A. L. (2012). Characterization of the aqueous iron(III) chelation chemistry of a potential Trojan Horse antimicrobial agent: chelate structure, stability and pH dependent speciation. Biometals : An International Journal on the Role of Metal Ions in Biology, Biochemistry, and Medicine, 25(5), 1023–1036. https://doi.org/10.1007/s10534-012-9568-0
Harrington, James M., Tom Gootz, Mark Flanagan, Majinder Lall, John O’Donnell, Jennifer Winton, John Mueller, and Alvin L. Crumbliss. “Characterization of the aqueous iron(III) chelation chemistry of a potential Trojan Horse antimicrobial agent: chelate structure, stability and pH dependent speciation.Biometals : An International Journal on the Role of Metal Ions in Biology, Biochemistry, and Medicine 25, no. 5 (October 2012): 1023–36. https://doi.org/10.1007/s10534-012-9568-0.
Harrington JM, Gootz T, Flanagan M, Lall M, O’Donnell J, Winton J, et al. Characterization of the aqueous iron(III) chelation chemistry of a potential Trojan Horse antimicrobial agent: chelate structure, stability and pH dependent speciation. Biometals : an international journal on the role of metal ions in biology, biochemistry, and medicine. 2012 Oct;25(5):1023–36.
Harrington, James M., et al. “Characterization of the aqueous iron(III) chelation chemistry of a potential Trojan Horse antimicrobial agent: chelate structure, stability and pH dependent speciation.Biometals : An International Journal on the Role of Metal Ions in Biology, Biochemistry, and Medicine, vol. 25, no. 5, Oct. 2012, pp. 1023–36. Epmc, doi:10.1007/s10534-012-9568-0.
Harrington JM, Gootz T, Flanagan M, Lall M, O’Donnell J, Winton J, Mueller J, Crumbliss AL. Characterization of the aqueous iron(III) chelation chemistry of a potential Trojan Horse antimicrobial agent: chelate structure, stability and pH dependent speciation. Biometals : an international journal on the role of metal ions in biology, biochemistry, and medicine. 2012 Oct;25(5):1023–1036.
Journal cover image

Published In

Biometals : an international journal on the role of metal ions in biology, biochemistry, and medicine

DOI

EISSN

1572-8773

ISSN

0966-0844

Publication Date

October 2012

Volume

25

Issue

5

Start / End Page

1023 / 1036

Related Subject Headings

  • beta-Lactams
  • Water
  • Spectrophotometry
  • Solutions
  • Potentiometry
  • Oxidation-Reduction
  • Molecular Structure
  • Ligands
  • Iron Chelating Agents
  • Hydrogen-Ion Concentration