Spectroscopic investigation of the different complexation and extraction properties of diastereomeric diglycolamide ligands

(2R,2 ' S)-2,2 '-oxybis-(N,N-didecylpropanamide) (cis-mTDDGA) and (2R,2 ' R)-2,2 '-oxybis-(N,N-didecylpropanamide) (trans-mTDDGA) were studied using time-resolved laser fluorescence spectroscopy (TRLFS), vibronic side-band spectroscopy (VSBS) and density functional theory calculations (DFT) to find reasons for their different extraction properties. Stability constants of the respective Cm(III) and Eu(III) complexes show cis-mTDDGA to be the superior ligand which is in agreement with results from extraction experiments. cis-mTDDGA extracts Cm(III) and Eu(III) as 1:3 complexes. In case of trans-mTDDGA, 1:2 complexes of the form [M(trans-mTDDGA)(2)(eta(1)-NO3)(H2O)(2)](2+) (M = Cm, Eu) are extracted additionally to the 1:3 complexes. VSBS and DFT confirm the presence of inner-sphere nitrate in the 1:2 complex.