The NMR method is used to study the features of the complexation kinetics of paramagnetic lanthanide cations with EDTA in aqueous media at temperature and pD variation. The acidity of solutions is determined by the potentiometric method with a glass electrode. By the dynamic NMR method it is found that the activation enthalpy of the association between EDTA complexones and Ln cations is ΔH = 71±5 kJ/mol in a temperature range from 290 K to 368 K (at pD = 1.6). The obtained results indicate that Ho and Pr complexes with EDTA are promising compounds as in vivo NMR thermosensors for biology and medicine.
- aqueous solutions