NMR STUDY OF THE TEMPERATURE DEPENDENCE OF PARAMAGNETIC CHEMICAL SHIFTS OF [Dy(DTPA)]2– IN SOLUTIONS AT VARIOUS pH VALUES

The NMR spectra of complex [Dy(DTPA)] 2– are studied at various temperatures and pH values of the aqueous solution. The NMR signals of [Dy(DTPA)] 2– are most sensitive to temperature changes (the maximum temperature sensitivity is 2.2 ppm/K at pH = 7.4) and are almost insensitive to pH changes in the range from 3.3 to 11.0. A significant change of chemical shifts is observed only in the pH region from 3.3 to 1.1 due to the formation of protonated forms of the complexes. [Dy(DTPA)] 2– can be considered as a promising reagent for temperature determination in aqueous media using in vitro and in vivo NMR.