Interaction of [Ln(DO2A)(H2O)2-3]+ and [Ln(DO2P)(H2O)2-3]- with phosphate, acetate and fluoride anions in aqueous solution

K. Kimpe, W. D'Olieslager, C. Görller-Walrand, A. Figueirinha, Z. Kovács, C. F G C Geraldes

Research output: Contribution to journalConference article

11 Scopus citations

Abstract

Mixed complexation of the lanthanide(III) chelates of the 1,7-disubstituted tetraazacyclododecane macrocycles DO2A and DO2P with phosphate, acetate and fluoride anions was studied in aqueous solutions using high resolution 1H and 31P NMR spectroscopy. The [La(DO2A)(H2O)2-3]+ and [Ce(DO2A)(H2O)2-3]+ chelates readily decompose in aqueous solutions containing phosphate anions. [Nd(DO2A)(H2O)2-3]+ and [Eu(DO2A)(H2O)2-3]+ chelates remain stable in an acetate environment. Association constants for the 1:1 adduct were obtained via 1H NMR titrations. In a fluoride environment, [La(DO2A)(H2O)2-3]+ was found to be unstable, in contrast to [Eu(DO2A)(H2O)2-3]+, for which the association constant for the 1:1 adduct was calculated. Chelate formation, as well as mixed complexation with fluoride and phosphate was studied for [Eu(DO2P)(H2O)2-3]-. The 31P chemical shifts of [Eu(DO2P)(H2O)2-3]- indicate that the DO2P macrocycle forms an 'in-cage' complex with binding through all four nitrogens. The [Eu(DO2P)(H2O)2-3]- chelate gradually decomposes in a phosphate environment, but remains stable in an fluoride environment.

Original languageEnglish (US)
Pages (from-to)828-832
Number of pages5
JournalJournal of Alloys and Compounds
Volume323-324
DOIs
StatePublished - Jul 12 2001
Event4th International Conference on f-Elements - Madrid, Spain
Duration: Sep 17 2000Sep 21 2000

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Keywords

  • Lanthanides
  • MRI contrast agents
  • Nuclear resonances
  • Rare earths

ASJC Scopus subject areas

  • Mechanics of Materials
  • Mechanical Engineering
  • Metals and Alloys
  • Materials Chemistry

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