The tris complexes of anions of chelidamic acid (H3CA, 4-hydroxypyridine-2,6-dicarboxylic acid) with dysprosium(III) and thulium(III) have been tested as aqueous shift reagents for the NMR peaks of metal cations. The Dy(CA)36- complex was observed to produce significant upfield isotropic hyperfine shifts of the 25Mg2+, 39K+, and 23Na+ resonances (as well as that of 87Rb+ and the 14N resonance of NH4+). The Tm(CA)36- complex produces a downfield shift of the 23Na+ peak. The shifts are produced by an interaction between cation and shift reagent anion, which is labile on the chemical shift NMR time scale. The shifts are strongly pH dependent due to protonation of the coordinated ligands.
ASJC Scopus subject areas
- Physical and Theoretical Chemistry
- Inorganic Chemistry