Selective Extraction of Americium(III) over Europium(III) Ions with Pyridylpyrazole Ligands: Structure–Property Relationships

Su, Dongping; Liu, Ying; Li, Shimeng; Ding, Songdong; Jin, Yongdong; Wang, Zhipeng; Hu, Xiaoyang; Zhang, Lirong

doi:10.1002/ejic.201601011

Cited by 23 publications

(24 citation statements)

References 42 publications

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“…The force field parameters for Am(III) were taken from the study by Spezia et al 30 Force field parameters for the BMIM cation were taken from the study by Prado et al 31 and the NTf 2 anion from the study by Lopez et al 32 The Lennard−Jones interaction parameters were calculated using the Lorentz−Berthelot mixing rule. Our simulated density of 1.421 ± 0.026 g/cm 3 for the [BMIM]-[NTf 2 ] IL is in agreement with the experimental value of 1.437 g/cm 3 . 33 See the Supporting Information for details on the force field parameters.…”

Section: Introductionsupporting

confidence: 88%

“…1−3 It could be achieved by taking advantage of spatial extensions of 5f, 6d, 7s, and 7p orbitals of actinides. As a result, actinides such as Am(III) bond efficiently with ligands consisting of soft donor atoms such as N and S. 3 Several such types of ligands are reported in the literature, for example, BTPhen, 4 BTBP, 5 BTP, 6 and TPTZ, 7 among others. These ligands display good separation coefficients for actinides over lanthanides, but they are not stable and exhibit hydrolytic and radiolytic instability.…”

Section: Introductionmentioning

confidence: 99%

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Molecular Dynamics Simulations of Complexation of Am(III) with a Preorganized Dicationic Ligand in an Ionic Liquid

Singh

Popovs

et al. 2021

J. Phys. Chem. B

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Preorganized ligands with imidazolium arms have been found to be highly selective in extracting Am(III) into ionic liquids (ILs), but the detailed structure and mechanism of the complexation process in the ionic solvation environment are unclear. Here, we carry out molecular dynamics simulation of the complexation of Am(III) with a preorganized 1,10-phenanthroline-2,9-dicarboxamide complexant (L) functionalized with alkyl chains and imidazolium cations in the butylmethylimidazolium bistriflimide ([BMIM][NTf2]) IL. Both Am:L (1:1) and Am:L2 (1:2) complexes are examined. In the absence of the ligand, Am(III) is found to be coordinated by six NTf2 anions via nine O donors in the first solvation shell. In the Am:L complex, Am(III) is coordinated to the ligand via two O donors and four NTf2 anions via seven O donors in the first coordination shell. In the Am:L2 complex, Am(III) is coordinated to the two ligands via four O donors and four NTf2 anions via five O donors. The imidazolium arms of the ligands play an important role in the secondary solvation environment by attracting NTf2 anions closer to the metal center. As a result, we find that the binding free energy for the second L2+ ligand is twice that for the first L2+ ligand, making the Am:L2 complex significantly more stable than the Am:L complex. This work highlights the multiple factors and tunability in using preorganized ligands with charged functional groups in an ionic solvation environment, which could hold the key to achieving desired selectivity in ion extraction efficiency.

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Section: Introductionsupporting

confidence: 88%

Section: Introductionmentioning

confidence: 99%

Molecular Dynamics Simulations of Complexation of Am(III) with a Preorganized Dicationic Ligand in an Ionic Liquid

Singh

Popovs

et al. 2021

J. Phys. Chem. B

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“…Ding et al obtained the 1:2 type single crystal structure of Eu(III) with PypzH . Hence, we also explored the structures of 1:2 type complexes of the Am(III) and Eu(III) ions with the ligand PypzH.…”

Section: Resultsmentioning

confidence: 99%

“…It has been shown that ligands Cn-PypzH behaves better in selective extraction of Am(III) ions compared to Cn-Pypz due to more steric hindrance of the substituted chain at the 2-position of the pyrazole ring. Moreover, the length of the alkyl-substituted chain has a significant impact on the distribution ratios and the separation factor of Am(III)/Eu(III) . Therefore, to explore the mechanism of Am(III)/Eu(III) separation of PypzH ligands with different alkyl-substituents and to compare the contribution of pyridine and pyrazole rings to the Am(III)/Eu(III) separation, we have systematically studied the extraction behavior of Cn-PypzH using relativistic quantum-chemical calculations.…”

Section: Introductionmentioning

confidence: 99%

Insight into the Extraction Mechanism of Americium(III) over Europium(III) with Pyridylpyrazole: A Relativistic Quantum Chemistry Study

Kong

Wang

et al. 2018

J. Phys. Chem. A

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Separation of trivalent actinides (An(III)) and lanthanides (Ln(III)) is one of the most important steps in spent nuclear fuel reprocessing. However, it is very difficult and challenging to separate them due to their similar chemical properties. Recently the pyridylpyrazole ligand (PypzH) has been identified to show good separation ability toward Am(III) over Eu(III). In this work, to explore the Am(III)/Eu(III) separation mechanism of PypzH at the molecular level, the geometrical structures, bonding nature, and thermodynamic behaviors of the Am(III) and Eu(III) complexes with PypzH ligands modified by alkyl chains (Cn-PypzH, n = 2, 4, 8) have been systematically investigated using scalar relativistic density functional theory (DFT). According to the NBO (natural bonding orbital) and QTAIM (quantum theory of atoms in molecules) analyses, the M-N bonds exhibit a certain degree of covalent character, and more covalency appears in Am-N bonds compared to Eu-N bonds. Thermodynamic analyses suggest that the 1:1 extraction reaction, [M(NO)(HO)] + PypzH + 2NO → M(PypzH)(NO)(HO) + 5HO, is the most suitable for Am(III)/Eu(III) separation. Furthermore, the extraction ability and the Am(III)/Eu(III) selectivity of the ligand PypzH is indeed enhanced by adding alkyl-substituted chains in agreement with experimental observations. Besides this, the nitrogen atom of pyrazole ring plays a more significant role in the extraction reactions related to Am(III)/Eu(III) separation compared to that of pyridine ring. This work could identify the mechanism of the Am(III)/Eu(III) selectivity of the ligand PypzH and provide valuable theoretical information for achieving an efficient Am(III)/Eu(III) separation process for spent nuclear fuel reprocessing.

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“…Subsequently, a Claisen condensation with an alkylmethylketone (whose alkyl chain is also the substituent of the pyridylpyrazole) formed the 1,3-diketone system, followed by cyclisation with position is involved in the formation of the complex and its alkylation blocks the ligating site. 264 The preparation of pyridyltriazolyl ligands (BPyTz-1-3, Chart 2.53) could be simply achieved by a copper-catalysed cycloaddition between 2,6-diethynylpyridine and hydrophilic azides. Despite the structural similarity to bis-pyridylpyrazole ligands, these ligands were successfully used as stripping agents from TODGA solutions.…”

Section: Chart 250mentioning

confidence: 99%

Alkylation and pre-organisation of diglycolamide ligands on flexible platforms for nuclear waste treatment

Leoncini

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Selective Extraction of Americium(III) over Europium(III) Ions with Pyridylpyrazole Ligands: Structure–Property Relationships

Cited by 23 publications

References 42 publications

Molecular Dynamics Simulations of Complexation of Am(III) with a Preorganized Dicationic Ligand in an Ionic Liquid

Molecular Dynamics Simulations of Complexation of Am(III) with a Preorganized Dicationic Ligand in an Ionic Liquid

Insight into the Extraction Mechanism of Americium(III) over Europium(III) with Pyridylpyrazole: A Relativistic Quantum Chemistry Study

Alkylation and pre-organisation of diglycolamide ligands on flexible platforms for nuclear waste treatment

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