Variable temperature H-1 and C-13 NMR spectra and proton and carbon longitudinal relaxation times allow the complete characterization of the solution structure and dynamics of three Ln(III) complexes of DTPA (Ln = La, Pr and Eu). Our results show that a rapid interconversion between octadentate structures occurs on the NMR time scale which can be 'frozen out' at low temperature for Pr and Eu complexes.