화학공학소재연구정보센터
Inorganic Chemistry, Vol.57, No.4, 2122-2131, 2018
Thermodynamic, Structural, and Computational Investigation on the Complexation between UO22+ and Amine-Functionalized Diacetamide Ligands in Aqueous Solution
The stability constants (log beta), enthalpies of complexation (Delta H), and entropies of complexation (Delta S) for the complexes of uranium(VI) with a series of amine-functionalized diaetamide ligands, 2,2'-benzyl-azanediylbis(N,N'-dimethylacetamide) (BnABDMA), 2,2'-azanediyl-bis(N,N'-dimethylacet amide ) (ABDMA), and 2,2'-methylazane diylbis (N,N'-dimethylacetamide ) (MABDMA), in aqueous solution were determined by potentiometry and calorimetry. Electron-spray ionization mass spectrometry was used to verify the presence of uranium(VI) complexes in solution. The thermodynamic data indicate that the binding strengths of the three ligands with UO22+ follow the order BnABDMA < ABDMA < MABDMA, parallel to the order of the protonation constants as well as the order of the stability of the Nd3+ complexes, suggesting that the complexation of UO22+ with the ligands consist predominantly of electrostatic interactions. Denisty functional theory calculations were conducted to reveal the structures, electronic charge distribution, and energetics of the uranium(VI) complexes, providing insight into the thermodynamic trends of the complexation. Extended X-ray absorption fine structure spectroscopy was used to identify the structures of the uranium(VI) complexes in aqueous solution.