Study of thermodynamic and kinetic stability of transition metal and lanthanide complexes of DTPA analogues with a phosphorus acid pendant arm

Jan Kotek, Ferenc K. Kálmán, Petr Hermann, E. Brücher, Koen Binnemans, Ivan Lukeš

Research output: Contribution to journalArticle

28 Citations (Scopus)

Abstract

The thermodynamic and kinetic stabilities of the complexes of phosphonate and phenylphosphinate analogues of H5dtpa with selected transition- and lanthanide-metal ions are presented. Both phosphorus-containing ligands form thermodynamically very stable complexes, with stability constants comparable with or even higher than those reported for the parent H5dtpa. However, the kinetic inertness of their gadolinium(III) complexes against acid- and metal-assisted decomplexations is surprisingly much lower. The half-life times of gadolinium(III) complexes of the new ligands in the presence of excess of concurrent metal ions [copper(II) or europium(III)] are about 2-3 orders of magnitude shorter compared to H5dtpa and its amide derivatives. The behaviour can probably be attributed to steric strain in the new complexes, to the high affinity of phosphonate ligand for proton, and/or to easy formation of binuclear complexes, which act as intermediates in the complex dissociation.

Original languageEnglish
Pages (from-to)1976-1986
Number of pages11
JournalEuropean Journal of Inorganic Chemistry
Issue number10
DOIs
Publication statusPublished - May 22 2006

Fingerprint

Phosphorus Acids
Lanthanoid Series Elements
Pentetic Acid
Transition metals
Organophosphonates
Gadolinium
Thermodynamics
Ligands
Kinetics
Metal ions
Europium
Amides
Phosphorus
Protons
Copper
Metals
Derivatives
Acids

Keywords

  • Kinetics
  • MRI contrast agents
  • Phosphinate complexes
  • Phosphonate complexes
  • Thermodynamics

ASJC Scopus subject areas

  • Inorganic Chemistry

Cite this

Study of thermodynamic and kinetic stability of transition metal and lanthanide complexes of DTPA analogues with a phosphorus acid pendant arm. / Kotek, Jan; Kálmán, Ferenc K.; Hermann, Petr; Brücher, E.; Binnemans, Koen; Lukeš, Ivan.

In: European Journal of Inorganic Chemistry, No. 10, 22.05.2006, p. 1976-1986.

Research output: Contribution to journalArticle

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AU - Binnemans, Koen

AU - Lukeš, Ivan

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N2 - The thermodynamic and kinetic stabilities of the complexes of phosphonate and phenylphosphinate analogues of H5dtpa with selected transition- and lanthanide-metal ions are presented. Both phosphorus-containing ligands form thermodynamically very stable complexes, with stability constants comparable with or even higher than those reported for the parent H5dtpa. However, the kinetic inertness of their gadolinium(III) complexes against acid- and metal-assisted decomplexations is surprisingly much lower. The half-life times of gadolinium(III) complexes of the new ligands in the presence of excess of concurrent metal ions [copper(II) or europium(III)] are about 2-3 orders of magnitude shorter compared to H5dtpa and its amide derivatives. The behaviour can probably be attributed to steric strain in the new complexes, to the high affinity of phosphonate ligand for proton, and/or to easy formation of binuclear complexes, which act as intermediates in the complex dissociation.

AB - The thermodynamic and kinetic stabilities of the complexes of phosphonate and phenylphosphinate analogues of H5dtpa with selected transition- and lanthanide-metal ions are presented. Both phosphorus-containing ligands form thermodynamically very stable complexes, with stability constants comparable with or even higher than those reported for the parent H5dtpa. However, the kinetic inertness of their gadolinium(III) complexes against acid- and metal-assisted decomplexations is surprisingly much lower. The half-life times of gadolinium(III) complexes of the new ligands in the presence of excess of concurrent metal ions [copper(II) or europium(III)] are about 2-3 orders of magnitude shorter compared to H5dtpa and its amide derivatives. The behaviour can probably be attributed to steric strain in the new complexes, to the high affinity of phosphonate ligand for proton, and/or to easy formation of binuclear complexes, which act as intermediates in the complex dissociation.

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KW - MRI contrast agents

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KW - Thermodynamics

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