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Shi C, Xiong S, Li S, Shen X. Improvement on the Radiation Stability of Multi-scale Supramolecular Assembly in Ionic Liquid-Based Extraction. J Phys Chem B 2023; 127:7334-7341. [PMID: 37578858 DOI: 10.1021/acs.jpcb.3c02786] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 08/16/2023]
Abstract
The multi-scale supramolecular assembly (MSSA)-based extraction strategy with hydroxyl-functionalized ionic liquid (IL) is promising in the separation of metal ions from radioactive environments for which a comprehensive understanding toward the radiation stability of the MSSA system is necessary. Herein, we report on the analyses of the radiation stability of MSSA in extraction, especially the adopted ILs 1-(2-hydroxyethyl)-3-methylimidazolium bis(trifluoromethylsulfonyl) imide (IL-1) and 1-(2-hydroxyethyl)-2,3-dimethylimidazolium bis(trifluoromethylsulfonyl) imide (IL-2), by UV-vis, 1H NMR, and ESI-HRMS. It was found that the macroscopic assembly (MA) sphere could not be formed after γ irradiation on the extraction system with IL-1. On the contrary, the trisubstituted IL-2 instead of the disubstituted IL-1 remarkably improved the radiation stability of the MSSA system to guarantee the formation of the MA sphere. The high extraction efficiency could be kept, and the mechanism of such an improvement was revealed.
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Affiliation(s)
- Ce Shi
- Beijing National Laboratory for Molecular Sciences (BNLMS), Fundamental Science on Radiochemistry and Radiation Chemistry Laboratory, Center for Applied Physics and Technology, College of Chemistry and Molecular Engineering, Peking University, Beijing 100871, P. R. China
| | - Shijie Xiong
- Beijing National Laboratory for Molecular Sciences (BNLMS), Fundamental Science on Radiochemistry and Radiation Chemistry Laboratory, Center for Applied Physics and Technology, College of Chemistry and Molecular Engineering, Peking University, Beijing 100871, P. R. China
| | - Shengxiang Li
- Beijing National Laboratory for Molecular Sciences (BNLMS), Fundamental Science on Radiochemistry and Radiation Chemistry Laboratory, Center for Applied Physics and Technology, College of Chemistry and Molecular Engineering, Peking University, Beijing 100871, P. R. China
| | - Xinghai Shen
- Beijing National Laboratory for Molecular Sciences (BNLMS), Fundamental Science on Radiochemistry and Radiation Chemistry Laboratory, Center for Applied Physics and Technology, College of Chemistry and Molecular Engineering, Peking University, Beijing 100871, P. R. China
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Molecular Liquids versus Ionic Liquids: The Interplay between Inter-Molecular and Intra-Molecular Hydrogen Bonding as Seen by Vaporisation Thermodynamics. MOLECULES (BASEL, SWITZERLAND) 2023; 28:molecules28020539. [PMID: 36677599 PMCID: PMC9862684 DOI: 10.3390/molecules28020539] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 11/30/2022] [Revised: 12/31/2022] [Accepted: 01/01/2023] [Indexed: 01/09/2023]
Abstract
In this study, we determined the enthalpies of vaporisation for a suitable set of molecular and ionic liquids using modern techniques for vapour pressure measurements, such as the quartz crystal microbalance, thermogravimetric analysis (TGA), and gas chromatographic methods. This enabled us to measure reasonable vapour pressures, avoiding the problem of the decomposition of the ionic liquids at high temperatures. The enthalpies of vaporisation could be further analysed by applying the well-known "group contribution" methods for molecular liquids and the "centerpiece" method for ionic liquids. This combined approach allowed for the dissection of the enthalpies of vaporisation into different types of molecular interaction, including hydrogen bonding and the dispersion interaction in the liquid phase, without knowing the existing species in both the liquid and gas phases.
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Aprotic Ionic Liquids: A Framework for Predicting Vaporization Thermodynamics. Molecules 2022; 27:molecules27072321. [PMID: 35408720 PMCID: PMC9000287 DOI: 10.3390/molecules27072321] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2022] [Revised: 03/29/2022] [Accepted: 04/01/2022] [Indexed: 11/16/2022] Open
Abstract
Ionic liquids (ILs) are recognized as an environmentally friendly alternative to replacing volatile molecular solvents. Knowledge of vaporization thermodynamics is crucial for practical applications. The vaporization thermodynamics of five ionic liquids containing a pyridinium cation and the [NTf2] anion were studied using a quartz crystal microbalance. Vapor pressure-temperature dependences were used to derive the enthalpies of vaporization of these ionic liquids. Vaporization enthalpies of the pyridinium-based ionic liquids available in the literature were collected and uniformly adjusted to the reference temperature T = 298.15 K. The consistent sets of evaluated vaporization enthalpies were used to develop the “centerpiece”-based group-additivity method for predicting enthalpies of vaporization of ionic compounds. The general transferability of the contributions to the enthalpy of vaporization from the molecular liquids to the ionic liquids was established. A small, but not negligible correction term was supposed to reconcile the estimated results with the experiment. The corrected “centerpiece” approach was recommended to predict the vaporization enthalpies of ILs.
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Zhao P, Tong Y, Ma N, Han B, Dong X, Qi M. Molecular Dynamics Simulations and Experimental Studies of the Microstructure and Mechanical Properties of a Silicone Oil/Functionalized Ionic Liquid-Based Magnetorheological Fluid. ACS APPLIED MATERIALS & INTERFACES 2022; 14:10987-10997. [PMID: 35175022 DOI: 10.1021/acsami.1c23925] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
Magnetorheological (MR) fluids are smart materials that show enormous potential in vibration control, mechanical engineering, etc. However, the effects of the solid-liquid interface strength and the interaction strength between carrier liquid molecules on the mechanical properties and sedimentation stability of MR fluids have always been unresolved issues. This work presents a new type of MR fluid that has a novel carrier liquid, i.e., silicone oil (SO) mixed with a hydroxyl-functionalized ionic liquid (IL-OH). An all-atomic Fe/SO/IL-OH interface model for studying the relationship between mechanical properties and interface strength and intermolecular interactions is established. On the basis of simulation results and theoretical analyses, the mechanical properties and sedimentation stability of the SO/IL-OH-based MR fluids are thoroughly investigated by experiments. The results show that functional ionic liquids significantly improve the mechanical properties and sedimentation stability of MR fluids. These results are essentially attributed to the stronger solid-liquid interface strength, van der Waals forces, and hydrogen bonds between the silicone oil and the functional ionic liquid. The explicit results not only help elucidate the numerous phenomena involved in the research process for MR fluids at the atomic scale but also provide insightful information on the fabrication of high-performance MR fluids.
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Affiliation(s)
- Penghui Zhao
- School of Materials Science and Engineering, Dalian University of Technology, Dalian 116024, China
| | - Yu Tong
- School of Materials Science and Engineering, Dalian University of Technology, Dalian 116024, China
| | - Ning Ma
- School of Civil Engineering, Dalian University of Technology, Dalian 116024, China
| | - Baoguo Han
- School of Civil Engineering, Dalian University of Technology, Dalian 116024, China
| | - Xufeng Dong
- School of Materials Science and Engineering, Dalian University of Technology, Dalian 116024, China
| | - Min Qi
- School of Materials Science and Engineering, Dalian University of Technology, Dalian 116024, China
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Verevkin SP, Kondratev SO, Zaitsau DH, Zherikova KV, Ludwig R. Quantification and understanding of non-covalent interactions in molecular and ionic systems: Dispersion interactions and hydrogen bonding analysed by thermodynamic methods. J Mol Liq 2021. [DOI: 10.1016/j.molliq.2021.117547] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
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Golub B, Fumino K, Stange P, Fossog V, Hempelmann R, Ondo D, Paschek D, Ludwig R. Balance Between Contact and Solvent-Separated Ion Pairs in Mixtures of the Protic Ionic Liquid [Et 3NH][MeSO 3] with Water Controlled by Water Content and Temperature. J Phys Chem B 2021; 125:4476-4488. [PMID: 33899479 DOI: 10.1021/acs.jpcb.1c01850] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
The formation of aggregates of ionic species is a crucial process in liquids and solutions. Ion speciation is particularly interesting for the case of ionic liquids (ILs) since these Coulombic fluids consist solely of ions. Most of their unique properties, such as enthalpies of vaporization and conductivities, are strongly related to ion pair formation. Here, we show that the balance of hydrogen-bonded contact ion pairs (CIP) and solvent-separated (SIP) ion pairs in protic ionic liquids (PILs) and in their mixtures with water can be well understood by a combination of far-infrared (FIR) and mid-infrared (MIR) spectroscopy, density functional theory (DFT) calculations of PIL/water aggregates, and molecular dynamics (MD) simulations of PIL/water mixtures. This combined approach is applied to mixtures of triethylammonium methanesulfonate [Et3NH][MeSO3] with water. It is shown that ion speciation in this mixture depends on three parameters: the relative hydrogen bond acceptor strength of the counter ion and the molecular solvent, the solvent concentration, and the temperature. For selected PIL/water mixtures, the equilibrium constants for CIPs and SIPs were determined as a function of the solvent content and temperature. Finally, for the studied PIL/water mixtures, the transition from CIPs to SIPs could be understood on enthalpic and entropic grounds. A detailed picture of this interconversion process could be described at the molecular level by means of MD simulations. In addition, the concentration dependence of ion pair formation can be well understood with help of a simplified "cartoon-like" statistical model describing hydrogen bond redistribution.
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Affiliation(s)
- Benjamin Golub
- Institut für Chemie, Abteilung Physikalische und Theoretische Chemie, Universität Rostock, Albert-Einstein-Straße 21, D-18059 Rostock, Germany
| | - Koichi Fumino
- Institut für Chemie, Abteilung Physikalische und Theoretische Chemie, Universität Rostock, Dr.-Lorenz-Weg 2, D-18059 Rostock, Germany
| | - Peter Stange
- Institut für Chemie, Abteilung Physikalische und Theoretische Chemie, Universität Rostock, Dr.-Lorenz-Weg 2, D-18059 Rostock, Germany
| | - Verlaine Fossog
- Transfercenter Sustainable Electrochemistry, Saarland University and KIST Europe, D-66123 Saarbrücken, Germany
| | - Rolf Hempelmann
- Transfercenter Sustainable Electrochemistry, Saarland University and KIST Europe, D-66123 Saarbrücken, Germany
| | - Daniel Ondo
- Department of Physical Chemistry, University of Chemistry and Technology, Technicka 5, CZ-166 28 Prague 6, Czech Republic
| | - Dietmar Paschek
- Institut für Chemie, Abteilung Physikalische und Theoretische Chemie, Universität Rostock, Albert-Einstein-Straße 21, D-18059 Rostock, Germany
| | - Ralf Ludwig
- Institut für Chemie, Abteilung Physikalische und Theoretische Chemie, Universität Rostock, Dr.-Lorenz-Weg 2, D-18059 Rostock, Germany.,Leibniz Institut für Katalyse an der Universität Rostock, Albert-Einstein-Straße 29a, D-18059 Rostock, Germany
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Zaitsau DH, Ludwig R, Verevkin SP. Determination of the dispersion forces in the gas phase structures of ionic liquids using exclusively thermodynamic methods. Phys Chem Chem Phys 2021; 23:7398-7406. [PMID: 33876099 DOI: 10.1039/d0cp05439a] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Ionic liquids are described by a delicate balance of Coulomb interaction, hydrogen bonding and dispersion forces. Dissecting the different types of interactions from thermodynamic properties is still a challenge. Here, we show that comparison of vaporization enthalpies of tetra-alkyl-ammonium ionic liquids with bis(trifluoromethylsulfonyl)imide [NTf2]- anions and the related molecular liquids, trialkylamines, allows for determining dispersion interactions in the gas phase ion-pairs. For this purpose, we measured vapor pressures and vaporization enthalpies of these ionic and molecular liquids by using a quartz-crystal microbalance. For supporting these data, we determined the vaporization enthalpies additionally from experimental activity coefficients at infinite dilution. Characteristic alkyl chain length dependences of the vaporization enthalpies have been established and were used for quantifying the dispersion forces in the gas phase species. The dissected dispersion contributions suggest that the alkyl chains do not show star-like topologies but embrace the anion maximizing the dispersion interactions. For the longest alkyl chains with eight carbon atoms, the dispersion interaction is as strong as two and a half hydrogen bonds. The proportion of dispersion in the gas phase species depending on the number of methylene groups in the ammonium cations is strongly supported by quantum chemical calculations.
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Affiliation(s)
- Dzmitry H Zaitsau
- Universität Rostock, Institut für Chemie, Abteilung für Physikalische Chemie, Dr-Lorenz-Weg 2, 18059, Rostock, Germany.
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Chen J, Dong K, Liu L, Zhang X, Zhang S. Anti-electrostatic hydrogen bonding between anions of ionic liquids: a density functional theory study. Phys Chem Chem Phys 2021; 23:7426-7433. [PMID: 33876102 DOI: 10.1039/d0cp06718k] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Hydrogen bonds (HBs) play a crucial role in the physicochemical properties of ionic liquids (ILs). To date, HBs between cations and anions (Ca-An) or between cations (Ca-Ca) in ILs have been reported extensively. Here, we provided DFT evidence for the existence of HBs between anions (An-An) in the IL 1-(2-hydroxyethyl)-3-methylimidazolium 4-(2-hydroxyethyl)imidazolide [HEMIm][HEIm]. The thermodynamic stabilities of anionic, cationic, and H2O dimers together with ionic pairs were studied using potential energy scans. The results show that the cation-anion pair is the most stable one, while the HB in the anionic dimer possesses similar thermodynamic stability to the water dimer. The further geometric, spectral and electronic structure analyses demonstrate that the inter-anionic HB meets the general theoretical criteria of traditional HBs. The strength order of four HBs in complexes is cation-anion pair > H2O dimer ≈ cationic dimer > anionic dimer. The energy decomposition analysis indicates that induction and dispersion interactions are the crucial factors to overcome strong Coulomb repulsions, forming inter-anionic HBs. Finally, the presence of inter-anionic HBs in the ionic cluster has been confirmed by a global minimum search for a system containing two ionic pairs. Even though hydroxyl-functionalized cations are more likely to form HBs with anions, there are still inter-anionic HBs between hydroxyl groups in the low-lying structures. Our studies broaden the understanding of HBs in ionic liquids and support the recently proposed concept of anti-electrostatic HBs.
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Affiliation(s)
- Junwu Chen
- Beijing Key Laboratory of Ionic Liquids Clean Process, CAS Key Laboratory of Green Process and Engineering, State Key Laboratory of Multiphase Complex Systems, Institute of Process Engineering, Chinese Academy of Sciences, Beijing 100190, P. R. China.
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Philippi F, Welton T. Targeted modifications in ionic liquids - from understanding to design. Phys Chem Chem Phys 2021; 23:6993-7021. [PMID: 33876073 DOI: 10.1039/d1cp00216c] [Citation(s) in RCA: 48] [Impact Index Per Article: 16.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Ionic liquids are extremely versatile and continue to find new applications in academia as well as industry. This versatility is rooted in the manifold of possible ion types, ion combinations, and ion variations. However, to fully exploit this versatility, it is imperative to understand how the properties of ionic liquids arise from their constituents. In this work, we discuss targeted modifications as a powerful tool to provide understanding and to enable design. A 'targeted modification' is a deliberate change in the structure of an ionic liquid. This includes chemical changes in an experiment as well as changes to the parameterisation in a computer simulation. In any case, such a change must be purposeful to isolate what is of interest, studying, as far as is possible, only one concept at a time. The concepts can then be used as design elements. However, it is often found that several design elements interact with each other - sometimes synergistically, and other times antagonistically. Targeted modifications are a systematic way of navigating these overlaps. We hope this paper shows that understanding ionic liquids requires experimentalists and theoreticians to join forces and provides a tool to tackle the difficult transition from understanding to design.
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Affiliation(s)
- Frederik Philippi
- Department of Chemistry, Molecular Sciences Research Hub, Imperial College London, White City Campus, London W12 0BZ, UK.
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Leier J, Michenfelder NC, Unterreiner A. Understanding the Photoexcitation of Room Temperature Ionic Liquids. ChemistryOpen 2021; 10:72-82. [PMID: 33565733 PMCID: PMC7874249 DOI: 10.1002/open.202000278] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2020] [Revised: 10/26/2020] [Indexed: 12/14/2022] Open
Abstract
Photoexcitation of (neat) room temperature ionic liquids (RTILs) leads to the observation of transient species that are reminiscent of the composition of the RTILs themselves. In this minireview, we summarize state-of-the-art in the understanding of the underlying elementary processes. By varying the anion or cation, one aim is to generally predict radiation-induced chemistry and physics of RTILs. One major task is to address the fate of excess electrons (and holes) after photoexcitation, which implies an overview of various formation mechanisms considering structural and dynamical aspects. Therefore, transient studies on time scales from femtoseconds to microseconds can greatly help to elucidate the most relevant steps after photoexcitation. Sometimes, radiation may eventually result in destruction of the RTILs making photostability another important issue to be discussed. Finally, characteristic heterogeneities can be associated with specific physicochemical properties. Influencing these properties by adding conventional solvents, like water, can open a wide field of application, which is briefly summarized.
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Affiliation(s)
- Julia Leier
- Institute of Physical ChemistryKarlsruhe Institute of Technology (KIT)Fritz-Haber-Weg 276131KarlsruheGermany
| | - Nadine C. Michenfelder
- Institute of Physical ChemistryKarlsruhe Institute of Technology (KIT)Fritz-Haber-Weg 276131KarlsruheGermany
| | - Andreas‐Neil Unterreiner
- Institute of Physical ChemistryKarlsruhe Institute of Technology (KIT)Fritz-Haber-Weg 276131KarlsruheGermany
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Li H, Niemann T, Ludwig R, Atkin R. Effect of Hydrogen Bonding between Ions of Like Charge on the Boundary Layer Friction of Hydroxy-Functionalized Ionic Liquids. J Phys Chem Lett 2020; 11:3905-3910. [PMID: 32338913 DOI: 10.1021/acs.jpclett.0c00689] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Atomic force microscopy has been used to measure the lubricity of a series of ionic liquids (ILs) at mica surfaces in the boundary friction regime. A previously unreported cation bilayer structure is detected at the IL-mica interface due to the formation of H-bonds between the hydroxy-functionalized cations [(c-c) H-bonds], which enhances the ordering of the ions in the boundary layer and improves the lubrication. The strength of the cation bilayer structure is controlled by altering the strength of (c-c) H-bonding via changes in the hydroxyalkyl chain length, the cation charge polarizability, and the coordination strength of the anions. This reveals a new means of controlling IL boundary nanostructure via H-bonding between ions of the same charge, which can impact diverse applications, including surface catalysis, particle stability, electrochemistry, etc.
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Affiliation(s)
- Hua Li
- School of Molecular Sciences, The University of Western Australia, Perth, Western Australia 6009, Australia
- Centre for Microscopy, Characterisation and Analysis, The University of Western Australia, Perth, Western Australia 6009, Australia
| | - Thomas Niemann
- Universität Rostock, Institut für Chemie, Abteilung für Physikalische Chemie, Dr.-Lorenz-Weg 2, 18059 Rostock, Germany
- Department LL&M, University of Rostock, Albert-Einstein-Strasse 25, 18059 Rostock, Germany
| | - Ralf Ludwig
- Universität Rostock, Institut für Chemie, Abteilung für Physikalische Chemie, Dr.-Lorenz-Weg 2, 18059 Rostock, Germany
- Department LL&M, University of Rostock, Albert-Einstein-Strasse 25, 18059 Rostock, Germany
- Leibniz-Institut für Katalyse an der Universität Rostock e.V., Albert-Einstein-Strasse 29a, 18059 Rostock, Germany
| | - Rob Atkin
- School of Molecular Sciences, The University of Western Australia, Perth, Western Australia 6009, Australia
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