Unusually sharp dependence of water exchange rate versus lanthanide ionic radii for a series of tetraamide complexes

Shanrong Zhang, Kuangcong Wu, A. Dean Sherry

Research output: Contribution to journalArticle

53 Citations (Scopus)

Abstract

The tetraamide ligand, DOTA-tetra(glycine ethyl ester), forms complexes with the lanthanide(III) cations that exist in solution predominantly as the square antiprism structure with single, slowly exchanging inner-sphere water molecule. Variable-temperature 1H and 17O NMR studies revealed that the bound water lifetimes in these complexes were sharply dependent upon the ionic radius of Ln3+ cation. A novel lanthanide-induced shift technique was used to unmask the bound water 17O resonance of SmL3+ and YL3+ complexes from the bulk water resonance. The bound water lifetime (τM298) was ∼800 μs in the EuL3+ complex but became much shorter (several microseconds) for Ln3+ cations with larger and smaller ionic radii. This demonstrates that water exchange is exquisitely fine-tuned in this macrocyclic tetraamide system and that a variety of Ln3+ complexes meet with the exchange requirement, Δω*τM ≥ 1, necessary for an efficient MT agent.

Original languageEnglish (US)
Pages (from-to)4226-4227
Number of pages2
JournalJournal of the American Chemical Society
Volume124
Issue number16
DOIs
StatePublished - Apr 24 2002

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Lanthanoid Series Elements
Rare earth elements
Water
Cations
Positive ions
Amino acids
Esters
Ligands
Nuclear magnetic resonance
Molecules
Temperature

ASJC Scopus subject areas

  • Chemistry(all)

Cite this

Unusually sharp dependence of water exchange rate versus lanthanide ionic radii for a series of tetraamide complexes. / Zhang, Shanrong; Wu, Kuangcong; Sherry, A. Dean.

In: Journal of the American Chemical Society, Vol. 124, No. 16, 24.04.2002, p. 4226-4227.

Research output: Contribution to journalArticle

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