Theoretical studies on the complexation of uranyl with typical carboxylate and amidoximate ligands  

作　　者：XU ChaoFei SU Jing XU Xiang LI Jun 

机构地区：[1]Department of Chemistry & Key Laboratory of Organic Optoelectronics and Molecular Engineering of the Ministry of Education,Tsinghua University [2]Division of Nuclear Materials Science and Engineering,Shanghai Institute of Applied Physics,Chinese Academy of Sciences [3]Key Laboratory of Nuclear Radiation and Nuclear Energy Technology,Chinese Academy of Sciences [4]College of Chemistry and Pharmaceutical Sciences,Qingdao Agricultural University

出　　处：《Science China Chemistry》2013年第11期1525-1532,共8页中国科学（化学英文版）

基　　金：the financial support by the National Natural Science Foundation of China (NSFC) (20933003 and 91026003) to JL;the Strategic Priority Research Program of the Chinese Academy of Sciences (XDA02040104);NSFC (21201106);the China Postdoctoral Science Foundation (2012M520297) to JS

摘　　要：Understanding of the bonding nature of uranyl and various ligands is the key for designing robust sequestering agents for uranium extraction from seawater. In this paper thermodynamic properties related to the complexation reaction of uranyl（VI） in aqueous solution （i.e. existing in the form of UO2（H20）52＋） by several typical ligands （L） including acetate （CH3CO2）, bicar- bonate （HOCO2-）, carbonate （CO32-）, CH3（NH2）CNO- （acetamidoximate, AO-） and glutarimidedioximate （denoted as GDO2-） have been investigated by using relativistic density functional theory （DFT）. The geometries, vibrational frequencies, natural net charges, and bond orders of the formed uranyl-L complexes in aqueous solution are studied. Based on the DFT analysis we show that the binding interaction between uranyl and amidoximate ligand is the strongest among the selected complexes. The thermodynamics of the complexation reaction are examined, and the calculated results show that complexation of uranyl with amidoximate ligands is most preferred thermodynamically. Besides, reaction paths of the substitution complexation of solvated uranyl by acetate and AO have been studied, respectively. We have obtained two minima along the reaction path of solvated uranyl with acetate, the monodentate-acetate complex and the bidentate-acetate one, while only one minimum involving monodentate-AO complex has been located for AO- ligand. Comparing the energy barriers of the two reaction paths, we find that complexation of uranyl with AO is more difficult in kinetics, though it is more preferable in thermodynamics. These results show that theoretical studies can help to select efficient ligands with fine-tuned thermodynamic and kinetic properties for binding uranyl in seawater.Understanding of the bonding nature of uranyl and various ligands is the key for designing robust sequestering agents for uranium extraction from seawater.In this paper thermodynamic properties related to the complexation reaction of uranyl(VI)in aqueous solution(i.e.existing in the form of UO2(H2O)52+)by several typical ligands(L)including acetate(CH3CO2),bicarbonate(HOCO2),carbonate(CO32),CH3(NH2)CNO(acetamidoximate,AO)and glutarimidedioximate(denoted as GDO2)have been investigated by using relativistic density functional theory(DFT).The geometries,vibrational frequencies,natural net charges,and bond orders of the formed uranyl-L complexes in aqueous solution are studied.Based on the DFT analysis we show that the binding interaction between uranyl and amidoximate ligand is the strongest among the selected complexes.The thermodynamics of the complexation reaction are examined,and the calculated results show that complexation of uranyl with amidoximate ligands is most preferred thermodynamically.Besides,reaction paths of the substitution complexation of solvated uranyl by acetate and AO have been studied,respectively.We have obtained two minima along the reaction path of solvated uranyl with acetate,the monodentate-acetate complex and the bidentate-acetate one,while only one minimum involving monodentate-AO complex has been located for AO ligand.Comparing the energy barriers of the two reaction paths,we find that complexation of uranyl with AO is more difficult in kinetics,though it is more preferable in thermodynamics.These results show that theoretical studies can help to select efficient ligands with fine-tuned thermodynamic and kinetic properties for binding uranyl in seawater.

关 键 词：URANYL seawater CARBOXYLATE amidoximate COMPLEXATION THERMODYNAMICS density functional theory 

分 类 号：O641.4[理学—物理化学] O614.62[理学—化学]