19201-34-4Relevant academic research and scientific papers
Unprecedented Inversion of Selectivity and Extraordinary Difference in the Complexation of Trivalent f Elements by Diastereomers of a Methylated Diglycolamide
Wilden, Andreas,Kowalski, Piotr M.,Kla?, Larissa,Kraus, Benjamin,Kreft, Fabian,Modolo, Giuseppe,Li, Yan,Rothe, J?rg,Dardenne, Kathy,Geist, Andreas,Leoncini, Andrea,Huskens, Jurriaan,Verboom, Willem
supporting information, p. 5507 - 5513 (2019/03/26)
When considering f elements, solvent extraction is primarily used for the removal of lanthanides from ore and their recycling, as well as for the separation of actinides from used nuclear fuel. Understanding the complexation mechanism of metal ions with organic extractants, particularly the influence of their molecular structure on complex formation is of fundamental importance. Herein, we report an extraordinary (up to two orders of magnitude) change in the extraction efficiency of f elements with two diastereomers of dimethyl tetraoctyl diglycolamide (Me2-TODGA), which only differ in the orientation of a single methyl group. Solvent extraction techniques, extended X-ray absorption fine structure (EXAFS) measurements, and density functional theory (DFT) based ab initio calculations were used to understand their complex structures and to explain their complexation mechanism. We show that the huge differences observed in extraction selectivity results from a small change in the complexation of nitrate counter-ions caused by the different orientation of one methyl group in the backbone of the extractant. The obtained results give a significant new insight into metal–ligand complexation mechanisms, which will promote the development of more efficient separation techniques.
Synthesis and Am/Eu extraction of novel TODGA derivatives
Iqbal, Mudassir,Huskens, Jurriaan,Verboom, Willem,Sypula, Michal,Modolo, Giuseppe
experimental part, p. 827 - 837 (2011/12/02)
Various ligands with structural modifications of the N,N,N',N'-tetraoctyl- 3-oxapentanediamide (TODGA) skeleton were synthesised in good yields. These modifications include (1) the increase in chain length from one carbon to two carbons between the central ether oxygen atom and the amide moieties, (2) the addition of substituents on the carbon between the central oxygen atom and the amide moieties on one and both sides of the central oxygen, (3) the replacement of the central oxygen by a (substituted) nitrogen atom and (4) synthesis of a rigidified glycolamide. The effect of the structural modifications on their extraction behaviours toward Am(III) and Eu(III) at various nitric acid concentrations was studied. In most of the cases, the extraction does not exceed that of TODGA in the entire acidity range of 0.001-4mol/l HNO3. The extraction behaviour of monomethyl-TODGA derivative 10a resembles that of TODGA at high nitric acid concentrations. However, at lower acidities, its D values are much lower, which is beneficial for possible back-extraction steps. The aza-tripodal ligands 18a,b show reverse extraction properties compared to TODGA as far as the pH influence is concerned: at pH 2, the DAm values are 49.9 and 3.1, the DEu values are 5.9 and 0.2, and the S Am/Eu values are 8 and 11, respectively.
