Selective Extraction of Americium(III) over Europium(III) with the Pyridylpyrazole Based Tetradentate Ligands: Experimental and Theoretical Study

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• 作者：Jieru Wang ; Dongping Su ; Dongqi Wang ; Songdong Ding ; Chao Huang ; Huang Huang ; Xiaoyang Hu ; Zhipeng Wang ; Shimeng Li
• 刊名：Inorganic Chemistry
• 出版年：2015
• 出版时间：November 16, 2015
• 年：2015
• 卷：54
• 期：22
• 页码：10648-10655
• 全文大小：441K
• ISSN：1520-510X

文摘

1,3-Bis[3-(2-pyridyl)pyrazol-1-yl]propane (Bippp) and 1,2-bis[3-(2-pyridyl)pyrazyl-1-methyl]benzene (Dbnpp), the pyridylpyrazole based tetradentate ligands, were synthesized and characterized by MS, NMR, and FT-IR. The solvent extraction and complexation behaviors of Am(III) and Eu(III) with the ligands were investigated experimentally and theoretically. In the presence of 2-bromohexanoic acid, the two ligands can effectively extract Am(III) over Eu(III) and other rare earth(III) metals (RE(III)) in HNO₃ solution with the separation factors (SF_Am/RE) ranging from 15 to 60. Slope analyses showed that both Am(III) and Eu(III) were extracted as monosolvated species, which agrees well with the results observed from X-ray crystallography and MS analyses. The stability constants (log K) obtained from UV鈥搗is titration for Eu(III) complexes with Bippp and Dbnpp are 4.75 卤 0.03 and 4.45 卤 0.04, respectively. Both UV鈥搗is titration and solvent extraction studies indicated that Bippp had stronger affinity for Eu(III) than Dbnpp, which is confirmed by density functional theory (DFT) calculations. DFT calculations revealed that the AmL(NO₃)₃ (L = Bippp and Dbnpp) complexes are thermodynamically more stable in water than their Eu(III) analogues, which is caused by greater covalency of the Am鈥揘 than Eu鈥揘 bonds. Theoretical studies gave an insight into the nature of the M(III)鈥搇igand bonding interactions.