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Fang D, Yang X, Li J, Zhang Z, Gao Y, Xiao C. Preorganization Effects on Eu(III) Ion Coordination by Dipyridyl-Phenanthroline Ligands: A Combined Experimental and Theoretical Analysis. Inorg Chem 2024; 63:8171-8179. [PMID: 38655575 DOI: 10.1021/acs.inorgchem.4c00395] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/26/2024]
Abstract
Although 1,10-phenanthroline has been proven to hold a strong complexing capacity for f-block elements and their derivatives have been applied in many fields, research on more highly or completely rigid phenanthroline ligands is still rare due to the challenging syntheses. Here, we reported three tetradentate ligands 2,9-di(pyridin-2-yl)-1,10-phenanthroline (L1), 12-(pyridin-2-yl)-5,6-dihydroquinolino[8,7b][1,10]phenanthroline (L2), and 5,6,11,12-tetrahydrobenzo[2,1-b:3,4-b']bis([1,10]phenanthroline) (L3) with increasing preorganization on the side chain; among which, L3 is fully preorganized. Their complexation reactions with Eu(III) were systematically investigated by electrospray ionization mass spectrometry (ESI-MS), UV-vis titrations, and single-crystal structures. It is found that all three ligands form only 1:1 M/L complexes with Eu(III). The single-crystal structures revealed that the three ligands hold similar coordination modes, while their stability constants determined by UV-vis titrations were L3 (4.80 ± 0.01) > L2 (4.38 ± 0.01) > L1 (3.88 ± 0.01). This trend is supported not only by the thermodynamic stability of rigid ligands compared to free ligands but also by the conclusion that rigid ligands exhibit faster reaction rates (lower energy barrier) than free ligands kinetically. This work is helpful in providing theoretical guidance for the subsequent development of highly preorganized chelating ligands with strong coordination ability and high selectivity for f-block elements.
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Affiliation(s)
- Dong Fang
- College of Chemical and Biological Engineering, Zhejiang University, Hangzhou 310058, China
- Institute of Zhejiang University-Quzhou, Quzhou 324000, China
| | - Xiaofan Yang
- College of Chemical and Biological Engineering, Zhejiang University, Hangzhou 310058, China
| | - Jiarui Li
- Institute of Fundamental and Frontier Sciences, University of Electronic Science and Technology of China, Chengdu 611731, Sichuan, China
| | - Zhiyuan Zhang
- Institute of Fundamental and Frontier Sciences, University of Electronic Science and Technology of China, Chengdu 611731, Sichuan, China
| | - Yang Gao
- Institute of Fundamental and Frontier Sciences, University of Electronic Science and Technology of China, Chengdu 611731, Sichuan, China
| | - Chengliang Xiao
- College of Chemical and Biological Engineering, Zhejiang University, Hangzhou 310058, China
- Institute of Zhejiang University-Quzhou, Quzhou 324000, China
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2
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Le-Hoang G, Guénée L, Sommer Q, Piguet C. Tuning Selectivity and Stability in Heteroleptic Lanthanide Adducts by Ligand Design. Inorg Chem 2024; 63:3712-3723. [PMID: 38334740 DOI: 10.1021/acs.inorgchem.3c03710] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/10/2024]
Abstract
Terdentate ligands L10-L14 and their heteroleptic [LkLn(hfac)3] complexes (Ln = La, Eu, Gd, Er, or Y; H-hfac = 1,1,1,5,5,5-hexafluoropentane-2,4-dione) exhibit multifactorial correlations between the ligand's structural frameworks, including their level of preorganization and steric congestion and their affinities and selectivities for catching the trivalent lanthanide containers [Ln(hfac)3]. The polyaromatic ligand scaffolds could be stepwise modulated via lanthanide-template synthetic strategies, using intermolecular rhodium-catalyzed insertion reactions. The increasing level of preorganization along the L10 → L11 → L12 series leads to a duality in which larger thermodynamic formation constants with lanthanides in CD2Cl2 are accompanied by an unexpected decrease in the Ln-N affinities in the solid state, which could be assigned to a limited match between the lanthanide size and the enlarged preorganized cavities. On the contrary, a reduced stability is induced by the connection of additional methyl groups at position 1 of the benzimidazole moieties in L13 and L14, which is accompanied by an optimization of metal-nitrogen bond lengths. This study contributes to the rational design of highly stable neutral heteroleptic lanthanide β-diketonate adducts that resist dissociation in solution, a prerequisite for photophysical applications using these highly luminescent systems at the molecular level.
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Affiliation(s)
- Giau Le-Hoang
- Department of Inorganic and Analytical Chemistry, University of Geneva, 30 quai E. Ansermet, CH-1211 Geneva 4, Switzerland
| | - Laure Guénée
- Laboratory of Crystallography, University of Geneva, 24 quai E. Ansermet, CH-1211 Geneva 4, Switzerland
| | - Quentin Sommer
- Department of Inorganic and Analytical Chemistry, University of Geneva, 30 quai E. Ansermet, CH-1211 Geneva 4, Switzerland
| | - Claude Piguet
- Department of Inorganic and Analytical Chemistry, University of Geneva, 30 quai E. Ansermet, CH-1211 Geneva 4, Switzerland
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3
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Wang X, Nayak S, Wilson RE, Soderholm L, Servis MJ. Solvent effects on extractant conformational energetics in liquid-liquid extraction: a simulation study of molecular solvents and ionic liquids. Phys Chem Chem Phys 2024; 26:2877-2886. [PMID: 38048065 DOI: 10.1039/d3cp04680j] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/05/2023]
Abstract
Extractant design in liquid-liquid extraction (LLE) is a research frontier of metal ion separations that typically focuses on the direct extractant-metal interactions. However, a more detailed understanding of energetic drivers of separations beyond primary metal coordination is often lacking, including the role of solvent in the extractant phase. In this work, we propose a new mechanism for enhancing metal-complexant energetics with nanostructured solvents. Using molecular dynamics simulations with umbrella sampling, we find that the organic solvent can reshape the energetics of the extractant's intramolecular conformational landscape. We calculate free energy profiles of different conformations of a representative bidentate extractant, n-octyl(phenyl)-N,N-diisobutyl carbamoyl methyl phosphinoxide (CMPO), in four different solvents: dodecane, tributyl phosphate (TBP), and dry and wet ionic liquid (IL) 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ([EMIM][Tf2N]). By promoting reorganization of the extractant molecule into its binding conformation, our findings reveal how particular solvents can ameliorate this unfavorable step of the metal separation process. In particular, the charge alternating nanodomains formed in ILs substantially reduce the free energy penalty associated with extractant reorganization. Importantly, using alchemical free energy calculations, we find that this stabilization persists even when we explicitly include the extracted cation. These findings provide insight into the energetic drivers of metal ion separations and potentially suggest a new approach to designing effective separations using a molecular-level understanding of solvent effects.
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Affiliation(s)
- Xiaoyu Wang
- Chemical Sciences and Engineering Division, Argonne National Laboratory, 9700 S Cass Ave, Lemont, IL 60439, USA.
| | - Srikanth Nayak
- Chemical Sciences and Engineering Division, Argonne National Laboratory, 9700 S Cass Ave, Lemont, IL 60439, USA.
| | - Richard E Wilson
- Chemical Sciences and Engineering Division, Argonne National Laboratory, 9700 S Cass Ave, Lemont, IL 60439, USA.
| | - L Soderholm
- Chemical Sciences and Engineering Division, Argonne National Laboratory, 9700 S Cass Ave, Lemont, IL 60439, USA.
| | - Michael J Servis
- Chemical Sciences and Engineering Division, Argonne National Laboratory, 9700 S Cass Ave, Lemont, IL 60439, USA.
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Wang X, Servis MJ. Using Metadynamics to Reveal Extractant Conformational Free Energy Landscapes. J Phys Chem B 2024; 128:263-272. [PMID: 38095622 DOI: 10.1021/acs.jpcb.3c06637] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2024]
Abstract
Understanding the impact of extractant functionalization on metal-binding energetics in liquid-liquid extraction is essential to guide the development of better separation processes. Traditionally, computational extractant design uses electronic structure calculations on metal-ligand clusters to determine the metal-binding energy of the lowest energy state. Although highly accurate, this approach does not account for all of the relevant physics encountered under experimental conditions. Such methodologies often neglect entropic contributions such as temperature effects and ligand flexibility, in addition to approximating solvent-extractant interactions with implicit solvent models. In this study, we use classical molecular dynamics simulations with an advanced sampling method, metadynamics, to map out extractant molecule conformational free energies in the condensed phase. We generate the complete conformational landscape in solution for a family of bidentate malonamide-based extractants with different functionalizations of the headgroup and the side chains. In particular, we show how such alkyl functionalization reshapes the free energy landscape, affecting the free energy penalty of organizing the extractant into the cis-like metal-binding conformation from the trans-like conformation of the free extractant in solution. Specifically, functionalizing alkyl tails to the center of the headgroup has a greater influence on increasing molecular rigidity and disfavoring the binding conformation than functionalizing side chains. These findings are consistent with trends in metal-binding energetics based on experimentally reported distribution ratios. We also consider a different bidentate extractant molecule, carbamoylmethylphosphine oxide, and show how the choice of solvent can further reshape the conformational energetic landscape. This study demonstrates the feasibility of using molecular dynamics simulations with advanced sampling techniques to investigate extractant conformational energetics in solution, which, more broadly, will enable extractant design that accounts for entropic effects and explicit solvation.
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Affiliation(s)
- Xiaoyu Wang
- Chemical Sciences and Engineering Division, Argonne National Laboratory, 9700 S Cass Avenue, Lemont, Illinois 60439, United States
| | - Michael J Servis
- Chemical Sciences and Engineering Division, Argonne National Laboratory, 9700 S Cass Avenue, Lemont, Illinois 60439, United States
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Jennifer G A, Gao Y, Schreckenbach G, Varathan E. Periodic Trends in the Stabilization of Actinyls in Their Higher Oxidation States Using Pyrrophen Ligands. Inorg Chem 2023; 62:6920-6933. [PMID: 37104857 DOI: 10.1021/acs.inorgchem.3c00022] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/29/2023]
Abstract
Owing to the prominent existence and unique chemistry of actinyls, their complexation with suitable ligands is of significant interest. The complexation of high-valent actinyl moieties (An = U, Np, Pu and Am) with the acyclic sal-porphyrin analogue called "pyrrophen" (L(1)) and its dimethyl derivative (L(2)) with four nitrogen and two oxygen donor atoms was studied using relativistic density functional theory. Based on the periodic trends, the [UVO2-L(1)/L(2)]1- complexes show shorter bond lengths and higher bond orders that increase across the series of pentavalent actinyl complexes mainly due to the localization of the 5f orbitals. Among the hexavalent complexes, the [UVIO2-L(1)/L(2)] complexes have the shortest bonds. Following the uranyl complex, due to the plutonium turn, the [AmVIO2-L(1)/L(2)] complexes exhibit comparable properties with those of the former. Charge analysis suggests the complexation to be facilitated through ligand-to-metal charge transfer (LMCT) mainly through σ donation. Thermodynamic feasibility of complexation was modeled using hydrated actinyl moieties in aqueous medium and was found to be spontaneous. The dimethylated pyrrophen (L(2)) shows higher magnitudes of thermodynamic parameters indicating increased feasibility compared to the unsubstituted ligand (L(1)). Energy decomposition analysis (EDA) along with extended transition-state-natural orbitals for chemical valence theory (ETS-NOCV) analysis shows that the dominant electrostatic contributions decrease across the series and are counteracted by Pauli repulsion. Slight but considerable covalency is provided to hexavalent actinyl complexes by orbital contributions; this was confirmed by molecular orbital (MO) analysis that suggests strong covalency in americyl (VI) complexes. In addition to the pentavalent and hexavalent actinyl moieties, heptavalent actinyl species of neptunyl, plutonyl, and americyl were studied. Beyond the influence of the charges, the geometric and electronic properties point to the stabilization of neptunyl (VII) in the pyrrophen ligand environment, while the others shift to a lower (+VI) and relatively stable OS on complexation.
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Affiliation(s)
- Abigail Jennifer G
- Department of Chemistry, SRM Institute of Science and Technology, Kattankulathur 603203, Tamil Nadu, India
| | - Yang Gao
- Institute of Fundamental and Frontier Sciences, University of Electronic Science and Technology of China, Chengdu, Sichuan 610054, China
- NHC Key Laboratory of Nuclear Technology Medical Transformation (Mianyang Central Hospital), Mianyang 621010, China
| | - Georg Schreckenbach
- Department of Chemistry, University of Manitoba, Winnipeg, Manitoba R3T 2N2, Canada
| | - Elumalai Varathan
- Department of Chemistry, SRM Institute of Science and Technology, Kattankulathur 603203, Tamil Nadu, India
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Augustine LJ, Kasper JM, Forbes TZ, Mason SE, Batista ER, Yang P. Influencing Bonding Interactions of the Neptunyl (V, VI) Cations with Electron-Donating and -Withdrawing Groups. Inorg Chem 2023; 62:6055-6064. [PMID: 37000037 DOI: 10.1021/acs.inorgchem.2c04538] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/01/2023]
Abstract
Neptunium makes up the largest percentage of minor actinides found in spent nuclear fuel, yet separations of this element have proven difficult due to its rich redox chemistry. Developing new reprocessing techniques should rely on understanding how to control the Np oxidation state and its interactions with different ligands. Designing new ligands for separations requires understanding how to properly tune a system toward a desired trait through functionalization. Emerging technologies for minor actinide separations focus on ligands containing carboxylate or pyridine functional groups, which are desirable due to their high degree of functionalization. Here, we use DFT calculations to study the interactions of carboxylate and polypyridine ligands with the neptunyl cation [Np(V/VI)O2]+/2+. A systematic study is performed by varying the electronic properties of the carboxylate and polypyridine ligands through the inclusion of different electron-withdrawing and electron-donating R groups. We focus on how these groups can affect geometric properties, electronic structure, and bonding characterization as a function of the metal oxidation state and ligand character and discuss how these factors can play a role in neptunium ligand design principles.
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Affiliation(s)
- Logan J Augustine
- Theoretical Division, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, United States
- Department of Chemistry, University of Iowa, Iowa City, Iowa 52245, United States
| | - Joseph M Kasper
- Theoretical Division, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, United States
| | - Tori Z Forbes
- Department of Chemistry, University of Iowa, Iowa City, Iowa 52245, United States
| | - Sara E Mason
- Department of Chemistry, University of Iowa, Iowa City, Iowa 52245, United States
| | - Enrique R Batista
- Theoretical Division, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, United States
| | - Ping Yang
- Theoretical Division, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, United States
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7
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Lei XP, Wu QY, Wang CZ, Lan JH, Chai ZF, Nie CM, Shi WQ. Theoretical Insights into the Substitution Effect of Phenanthroline Derivatives on Am(III)/Eu(III) Separation. Inorg Chem 2023; 62:2705-2714. [PMID: 36724403 DOI: 10.1021/acs.inorgchem.2c03823] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
Separation of trivalent actinides (An(III)) and lanthanides (Ln(III)) poses a huge challenge in the reprocessing of spent nuclear fuel due to their similar chemical properties. N,N'-Diethyl-N,N'-ditolyl-2,9-diamide-1,10-phenanthroline (Et-Tol-DAPhen) is a potential ligand for the extraction of An(III) from Ln(III), while there are still few reports on the effect of its substituent including electron-withdrawing and electron-donating groups on An(III)/Ln(III) separation. Herein, the interaction of Et-Tol-DAPhen ligands modified by the electron-withdrawing groups (CF3, Br) and electron-donating groups (OH) with Am(III)/Eu(III) ions was investigated using scalar relativistic density functional theory (DFT). The analyses of bond order, quantum theory of atoms in molecules (QTAIM), and molecular orbital (MO) indicate that the substitution groups have a slight effect on the electronic structures of the [M(L-X)(NO3)3] (X = CF3, Br, OH) complexes. However, the thermodynamic results suggest that a ligand with the electron-donating group (L-OH) improves the extraction ability of metal ions, and the ligand modified by the electron-withdrawing group (L-Br) has the best Am(III)/Eu(III) selectivity. This work could render new insights into understanding the effect of electron-withdrawing and electron-donating groups in tuning the selectivity of Et-Tol-DAPhen derivatives and pave the way for designing new ligands modified by substituted groups with better extraction ability and An(III)/Ln(III) selectivity.
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Affiliation(s)
- Xia-Ping Lei
- School of Chemistry and Chemical Engineering, University of South China, Hengyang 421001, China.,Laboratory of Nuclear Energy Chemistry, Institute of High Energy Physics, Chinese Academy of Sciences, Beijing 100049, China
| | - Qun-Yan Wu
- Laboratory of Nuclear Energy Chemistry, Institute of High Energy Physics, Chinese Academy of Sciences, Beijing 100049, China
| | - Cong-Zhi Wang
- Laboratory of Nuclear Energy Chemistry, Institute of High Energy Physics, Chinese Academy of Sciences, Beijing 100049, China
| | - Jian-Hui Lan
- Laboratory of Nuclear Energy Chemistry, Institute of High Energy Physics, Chinese Academy of Sciences, Beijing 100049, China
| | - Zhi-Fang Chai
- Laboratory of Nuclear Energy Chemistry, Institute of High Energy Physics, Chinese Academy of Sciences, Beijing 100049, China
| | - Chang-Ming Nie
- School of Chemistry and Chemical Engineering, University of South China, Hengyang 421001, China
| | - Wei-Qun Shi
- Laboratory of Nuclear Energy Chemistry, Institute of High Energy Physics, Chinese Academy of Sciences, Beijing 100049, China
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Subramaniyan V, Tibika F, Tulchinsky Y. Effect of Internal Ligand Strain on Coordination Behavior of PSP Pincer Ligands. Inorg Chem 2023; 62:123-136. [PMID: 36544266 DOI: 10.1021/acs.inorgchem.2c03044] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Chelating ligands and most specifically pincer ligands, with their characteristic co-planar binding, usually undergo deformations upon coordination, resulting in a significant ligand strain. Such an effect on the properties of the so formed complex has rarely been explored. This study is an attempt to analyze this strain and its contribution to the overall binding energy and coordination behavior of PSP pincer ligands. Hence, we designed a rigid thioxanthone-based PSP pincer ligand (I) and studied the difference in the coordination properties with the more flexible thioxanthene and thioether-based PSP pincer ligands (II and III). Although with one equivalent of Pd(II) precursor, the three ligands exhibited a similar coordination behavior leading to similar κ3-P,S,P pincer complexes, an in-depth computational analysis pointed out the different contributions of the internal strain energy in lowering the binding energy of these complexes. This effect was clearly reflected when we calculated the enthalpy change of these ligand-exchange reactions. As these exchange reactions are enthalpy-driven, these results could also be confirmed experimentally. With two equivalents of Pd(II), the three ligands diverged in their coordination behavior. Specifically, ligands I and III gave each a binuclear complex, with different coordination modes, whereas the pincer complex of ligand II remained unaffected by excess of Pd(II). Our calculations suggest that the driving force for the formation of binuclear Pd(II) complexes is the relief of the internal ligand strain. With Pt(II), only the mononuclear κ3-P,S,P pincer complexes were obtained irrespectively of the amount of the Pt(II) precursor. In these cases, we assume that kinetic inertness of the formed mononuclear pincer Pt(II) complexes prevents binding of an additional Pt(II) nucleus. This study points out the important role of the internal ligand strain in PSP pincer ligand coordination behavior. We believe that our findings can be extended to other pincer ligands systems as well.
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Affiliation(s)
| | - Françoise Tibika
- Institute of Chemistry, The Hebrew University of Jerusalem, Jerusalem9190401, Israel
| | - Yuri Tulchinsky
- Institute of Chemistry, The Hebrew University of Jerusalem, Jerusalem9190401, Israel
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Lei XP, Wu QY, Wang CZ, Lan JH, Chai ZF, Nie CM, Shi WQ. Theoretical insights into the separation of Am( iii)/Eu( iii): designing ligands based on a preorganization strategy. Dalton Trans 2022; 51:16659-16667. [DOI: 10.1039/d2dt02474h] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The extraction behaviors of Am(iii) and Eu(iii) were investigated using phenanthroline and bipyridine ligands based on a preorganization strategy.
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Affiliation(s)
- Xia-Ping Lei
- Laboratory of Nuclear Energy Chemistry, Institute of High Energy Physics, Chinese Academy of Sciences, Beijing, 100049, China
- School of Chemistry and Chemical Engineering, University of South China, Hengyang, 421001, China
| | - Qun-Yan Wu
- Laboratory of Nuclear Energy Chemistry, Institute of High Energy Physics, Chinese Academy of Sciences, Beijing, 100049, China
| | - Cong-Zhi Wang
- Laboratory of Nuclear Energy Chemistry, Institute of High Energy Physics, Chinese Academy of Sciences, Beijing, 100049, China
| | - Jian-Hui Lan
- Laboratory of Nuclear Energy Chemistry, Institute of High Energy Physics, Chinese Academy of Sciences, Beijing, 100049, China
| | - Zhi-Fang Chai
- Laboratory of Nuclear Energy Chemistry, Institute of High Energy Physics, Chinese Academy of Sciences, Beijing, 100049, China
| | - Chang-Ming Nie
- School of Chemistry and Chemical Engineering, University of South China, Hengyang, 421001, China
| | - Wei-Qun Shi
- Laboratory of Nuclear Energy Chemistry, Institute of High Energy Physics, Chinese Academy of Sciences, Beijing, 100049, China
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