| dc.description.abstract | The isotropic hyperfine shifts induced in the 23Na+ resonance by the shift reagents Dy(DPA)33−, Dy(NTA)23−, Dy(PPP)27−, Tm(PPP)27−, Dy(TTHA)3−, and Tm(TTHA)3− are compared under similar conditions. The last three are introduced as shift reagents in this study. The Dy(PPP)37− and Tm(PPP)27− ions cause the largest shifts. However, these shifts are very pH dependent and are readily decreased by the presence of Ca2+ or Mg2+ ions. The Dy(TTHA)3− and Tm(TTHA)3− ions produce quite large shifts which are independent of pH (between 5.5 and 12) and less sensitive to Ca2+ and Mg2+. For a given chelate ligand, the analogous Dy(III) and Tm(III) complexes cause hyperfine shifts in opposite directions. However, while the Dy(PPP)27− ion induces an upfield shift, the Dy(TTHA)3− ion induces a downfield shift. Some data on shifts of the 25Mg2+, 39K+, and 87Rb+ resonances are also presented. In addition the 14N peak of NH4+ can be quite effectively shifted. DPA2−, dipicolinate pyridine-2 6-dicarboxylate; CA3−, chelidamate 4-oxypyridine-2,6-dicarboxylate; PPP5−, tripolyphosphate P3O105−; NTA3−, nitrilotriacetate N(CH2CO2)33−; EDTA4−, ethylenediaminetetraacetate (O2CCH2)2N(CH2)2N(CH2CO2)24−; TTHA6−, triethylenetetraminehexaacetate (O2CCH2)2N(CH2)2N(CH2CO2)(CH2)2N(CH2CO2)(CH2)2N(CH2CO2)26−; HTEA+, triethanolammonium (HOCH2CH2)3NH+; Ln, any of the elements from La to Lu; Δν1/2, width at half height; SR, shift reagent(s); RR, relaxation reagents(s); I, Ionic strength | en_US |
