Unique selectivity reversal between Am3+ and Eu3+ ions by incorporation of alkyl branching in diglycolamide derivatives: DFT validation of experimental results

Two diglycolamide (DGA) derivatives having n-butyl (nBuDGA) and s-butyl (sBuDGA) groups have been used for the extraction of Am3+ and Eu3+ to study the role of alkyl chain branching on their separation behaviour. Interestingly, the selectivity between Am3+ and Eu3+ reversed upon changing the ligand from nBuDGA to sBuDGA. An opposite trend was also observed in the extraction of lanthanide ions along the series of decreasing ionic radii for these two ligands. Luminescence and FTIR studies suggest a different nature of the Eu3+ complexes of these two ligands. DFT studies were performed to find out the structure and the electronic distribution of the Am3+ and Eu3+ complexes of these two ligands.