The effects of intramolecular H-bond formation on the stability constant and water exchange rate of the Gd(III)-diethylenetriamine-N′-(3-amino-1,1-propylenephosphonic)-N, N,N″,N″-tetraacetate complex

Zsolt Baranyai, Eliana Gianolio, Kondareddiar Ramalingam, Rolf Swenson, Ramachandran Ranganathan, E. Brücher, Silvio Aime

Research output: Contribution to journalArticle

15 Citations (Scopus)

Abstract

The binding interaction of metal chelates to biological macromolecules, though driven by properly devoted recognition synthons, may cause dramatic changes in some property associated with the coordination cage such as the thermodynamic stability or the exchange rate of the metal coordinated water. Such changes are due to electrostatic and H-bonding interactions involving atoms of the coordination cage and atoms of the biological molecule at the binding site. To mimic this type of H-bonding interactions, lanthanide(III) complexes with a DTPA-monophosphonate ligand bearing a propylamino moiety (H6NP-DTPA) were synthesized. Their thermodynamic stabilities and the exchange lifetime of the coordinated water molecule (for the Gd-complex) were compared with those of the analog complexes with DTPA and the parent DTPA-monophosphonate derivative (H6P-DTPA). It was found that the intramolecular H-bond between the -̇amino group and the phosphonate moiety in NP-DTPA complexes causes displacements of electric charges in their coordination cage that are markedly pH dependent. In turn, this affects the characteristic properties of the coordination cage. In particular it results in a marked elongation of the exchange lifetime of the coordinated water molecule.

Original languageEnglish
Pages (from-to)94-102
Number of pages9
JournalContrast Media and Molecular Imaging
Volume2
Issue number2
DOIs
Publication statusPublished - Mar 1 2007

Keywords

  • Contrast agents
  • Gadolinium complexes
  • MRI
  • Water exchange rate
  • pH potentiometry

ASJC Scopus subject areas

  • Radiology Nuclear Medicine and imaging

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