1
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Hunger L, Al Sheakh L, Fritsch S, Villinger A, Ludwig R, Harville P, Moss O, Lachowicz A, Johnson MA. Spectroscopic Evidence for Doubly Hydrogen-Bonded Cationic Dimers in the Solid, Liquid, and Gaseous Phases of Carboxyl-Functionalized Ionic Liquids. J Phys Chem B 2024; 128:5463-5471. [PMID: 38776534 DOI: 10.1021/acs.jpcb.4c02094] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/25/2024]
Abstract
Intermolecular interactions determine whether matter sticks together, gases condense into liquids, or liquids freeze into solids. The most prominent example is hydrogen bonding in water, responsible for the anomalous properties in the liquid phase and polymorphism in ice. The physical properties are also exceptional for ionic liquids (ILs), wherein a delicate balance of Coulomb interactions, hydrogen bonds, and dispersion interactions results in a broad liquid range and the vaporization of ILs as ion pairs. In this study, we show that strong, local, and directional hydrogen bonds govern the structures and arrangements in the solid, liquid, and gaseous phases of carboxyl-functionalized ILs. For that purpose, we explored the H-bonded motifs by X-ray diffraction and attenuated total reflection (ATR) infrared (IR) spectroscopy in the solid state, by ATR and transmission IR spectroscopy in the liquid phase, and by cryogenic ion vibrational predissociation spectroscopy (CIVPS) in the gaseous phase at low temperature. The analysis of the CO stretching bands reveals doubly hydrogen-bonded cationic dimers (c═c), resembling the archetype H-bond motif known for carboxylic acids. The like-charge doubly hydrogen-bonded ion pairs are present in the crystal structure of the IL, survive phase transition into the liquid state, and are still present in the gaseous phase even in (2,1) complexes wherein one counterion is removed and repulsive Coulomb interaction increased. The interpretation of the vibrational spectra is supported by quantum chemical methods. These observations have implications for the fundamental nature of the hydrogen bond between ions of like charge.
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Affiliation(s)
- Lasse Hunger
- Department of Chemistry, University of Rostock, 18059 Rostock, Germany
- Department Life, Light & Matter, University of Rostock, 18051 Rostock, Germany
| | - Loai Al Sheakh
- Department of Chemistry, University of Rostock, 18059 Rostock, Germany
- Department Life, Light & Matter, University of Rostock, 18051 Rostock, Germany
| | - Sebastian Fritsch
- Department of Chemistry, University of Rostock, 18059 Rostock, Germany
- Department Life, Light & Matter, University of Rostock, 18051 Rostock, Germany
| | | | - Ralf Ludwig
- Department of Chemistry, University of Rostock, 18059 Rostock, Germany
- Department Life, Light & Matter, University of Rostock, 18051 Rostock, Germany
- Leibniz-Institut für Katalyse e.V., Albert-Einstein-Str. 29a, 18059 Rostock, Germany
| | - Payten Harville
- Sterling Chemistry Laboratory, Yale University, New Haven, Connecticut 06520, United States
| | - Olivia Moss
- Sterling Chemistry Laboratory, Yale University, New Haven, Connecticut 06520, United States
| | - Anton Lachowicz
- Sterling Chemistry Laboratory, Yale University, New Haven, Connecticut 06520, United States
| | - Mark A Johnson
- Sterling Chemistry Laboratory, Yale University, New Haven, Connecticut 06520, United States
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2
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Hunger L, Ludwig R, Chuang YC, Chang HC. Hydroxy-Functionalized Ionic Liquids under Pressure: The Influence on Hydrogen Bonding between Ions of Opposite and Like Charges. J Phys Chem B 2024. [PMID: 38696327 DOI: 10.1021/acs.jpcb.4c01520] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/04/2024]
Abstract
Hydroxy functionalization of cations in ionic liquids (ILs) can lead to formation of hydrogen bonds between their OH groups, resulting in so-called (c-c) H-bonds. Thereby, the (c-c) H-bonds compete with regular H-bonds (c-a) between the OH groups and the anions. Polarizable cations, weakly interacting anions, and long alkyl chains at the cation support the propensity for the formation of (c-c) H-bonds. At low temperatures, the equilibrium between (c-c) and (c-a) H-bonds is strongly shifted in favor of the cation-cation interaction. Herein, we clarify the pressure dependence on (c-c) and (c-a) H-bond distributions in the IL 1-(2-hydroxyethyl)-3-methylimidazolium hexafluorophosphate [HOC2C1Im][PF6], in mixtures of [HOC2C1Im][PF6] with the nonhydroxy-functionalized IL 1-propyl-3-methylimidazolium hexafluorophosphate [C3C1Im][PF6] and in [HOC2C1Im][PF6] including trace amounts of water. The infrared (IR) spectra provide clear evidence that the (c-c) H-bonds diminish with increasing pressure in favor of the (c-a) H-bonds. Adding trace amounts of water results in enhanced (c-c) clustering due to cooperative effects. At ambient pressure, the water molecules are involved in the (c-c) H-bond motifs. Increasing pressure leads to squeezing them out of H-bond clusters, finally resulting in demixing of water and the IL at the microscopic level.
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Affiliation(s)
- Lasse Hunger
- Department of Chemistry, University of Rostock, 18059 Rostock, Germany
- Department Life, Light & Matter, University of Rostock, 18051 Rostock, Germany
| | - Ralf Ludwig
- Department of Chemistry, University of Rostock, 18059 Rostock, Germany
- Department Life, Light & Matter, University of Rostock, 18051 Rostock, Germany
- Leibniz-Institut für Katalyse e.V., Albert-Einstein-Str. 29a, 18059 Rostock, Germany
| | - Yen-Ching Chuang
- Department of Chemistry, National Dong Hwa University, Shoufeng, Hualien 974, Taiwan
| | - Hai-Chou Chang
- Department of Chemistry, National Dong Hwa University, Shoufeng, Hualien 974, Taiwan
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3
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Assessing the impact of increase in the number of hydroxyl groups on the microscopic behaviors of ammonium-based room temperature ionic liquids: A combined fluorescence up-conversion, fluorescence correlation and NMR spectroscopic study. J Photochem Photobiol A Chem 2023. [DOI: 10.1016/j.jphotochem.2022.114505] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
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Kumar Panja S, Kumar S. Weak Intra and Intermolecular Interactions via Aliphatic Hydrogen Bonding in Piperidinium Based Ionic Liquids: Experimental, Topological and Molecular Dynamics Studies. J Mol Liq 2023. [DOI: 10.1016/j.molliq.2023.121354] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
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5
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Hunger L, Al‐Sheakh L, Zaitsau DH, Verevkin SP, Appelhagen A, Villinger A, Ludwig R. Dissecting Noncovalent Interactions in Carboxyl‐Functionalized Ionic Liquids Exhibiting Double and Single Hydrogens Bonds Between Ions of Like Charge. Chemistry 2022; 28:e202200949. [PMID: 35785500 PMCID: PMC9543318 DOI: 10.1002/chem.202200949] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2022] [Indexed: 11/11/2022]
Affiliation(s)
- Lasse Hunger
- Institut für Chemie Abteilung für Physikalische Chemie Universität Rostock Albert-Einstein-Str. 27 18059 Rostock Germany
| | - Loai Al‐Sheakh
- Institut für Chemie Abteilung für Physikalische Chemie Universität Rostock Albert-Einstein-Str. 27 18059 Rostock Germany
| | - Dzmitry H. Zaitsau
- Institut für Chemie Abteilung für Physikalische Chemie Universität Rostock Albert-Einstein-Str. 27 18059 Rostock Germany
- Department LL&M University of Rostock Albert-Einstein-Str. 25 18059 Rostock Germany
| | - Sergey P. Verevkin
- Institut für Chemie Abteilung für Physikalische Chemie Universität Rostock Albert-Einstein-Str. 27 18059 Rostock Germany
- Department LL&M University of Rostock Albert-Einstein-Str. 25 18059 Rostock Germany
| | - Andreas Appelhagen
- Institut für Chemie Abteilung für Physikalische Chemie Universität Rostock Albert-Einstein-Str. 27 18059 Rostock Germany
| | - Alexander Villinger
- Institut für Chemie Abteilung für Anorganische Chemie Universität Rostock Albert-Einstein-Str. 3a 18059 Rostock Germany
| | - Ralf Ludwig
- Institut für Chemie Abteilung für Physikalische Chemie Universität Rostock Albert-Einstein-Str. 27 18059 Rostock Germany
- Department LL&M University of Rostock Albert-Einstein-Str. 25 18059 Rostock Germany
- Leibniz-Institut für Katalyse an der Universität Rostock e.V. Albert-Einstein-Str. 29a 18059 Rostock Germany
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6
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Khudozhitkov AE, Donoshita M, Stepanov AG, Philippi F, Rauber D, Hempelmann R, Kitagawa H, Kolokolov DI, Ludwig R. High‐Temperature Quantum Tunneling and Hydrogen Bonding Rearrangements Characterize the Solid‐Solid Phase Transitions in a Phosphonium‐Based Protic Ionic Liquid. Chemistry 2022; 28:e202200257. [PMID: 35187737 PMCID: PMC9311734 DOI: 10.1002/chem.202200257] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2022] [Indexed: 11/11/2022]
Affiliation(s)
- Alexander E. Khudozhitkov
- Boreskov Institute of Catalysis Siberian Branch of Russian Academy of Sciences Prospekt Akademika Lavrentieva 5 Novosibirsk 630090 Russia
- Novosibirsk State University Pirogova Street 2 Novosibirsk 630090 Russia
| | - Masaki Donoshita
- Division of Chemistry Graduate School of Science Kyoto University Kitashirakawa-Oiwakecho, Sakyo-ku Kyoto 606-8502 Japan
| | - Alexander G. Stepanov
- Boreskov Institute of Catalysis Siberian Branch of Russian Academy of Sciences Prospekt Akademika Lavrentieva 5 Novosibirsk 630090 Russia
- Novosibirsk State University Pirogova Street 2 Novosibirsk 630090 Russia
| | - Frederik Philippi
- Physikalische Chemie Universität des Saarlandes Campus B2.2 66123 Saarbrücken Germany
| | - Daniel Rauber
- Physikalische Chemie Universität des Saarlandes Campus B2.2 66123 Saarbrücken Germany
| | - Rolf Hempelmann
- Physikalische Chemie Universität des Saarlandes Campus B2.2 66123 Saarbrücken Germany
| | - Hiroshi Kitagawa
- Division of Chemistry Graduate School of Science Kyoto University Kitashirakawa-Oiwakecho, Sakyo-ku Kyoto 606-8502 Japan
| | - Daniil I. Kolokolov
- Boreskov Institute of Catalysis Siberian Branch of Russian Academy of Sciences Prospekt Akademika Lavrentieva 5 Novosibirsk 630090 Russia
- Novosibirsk State University Pirogova Street 2 Novosibirsk 630090 Russia
| | - Ralf Ludwig
- Department LL&M University of Rostock Albert-Einstein-Str. 25 18059 Rostock Germany
- Institut für Chemie Abteilung für Physikalische Chemie Universität Rostock Dr.-Lorenz-Weg 2 18059 Rostock Germany
- Leibniz-Institut für Katalyse Universität Rostock e.V. Albert-Einstein-Str. 29a 18059 Rostock Germany
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7
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Al-Sheakh L, Fritsch S, Appelhagen A, Villinger A, Ludwig R. Thermodynamically Stable Cationic Dimers in Carboxyl-Functionalized Ionic Liquids: The Paradoxical Case of "Anti-Electrostatic" Hydrogen Bonding. Molecules 2022; 27:molecules27020366. [PMID: 35056680 PMCID: PMC8778807 DOI: 10.3390/molecules27020366] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2021] [Revised: 12/28/2021] [Accepted: 01/03/2022] [Indexed: 11/18/2022] Open
Abstract
We show that carboxyl-functionalized ionic liquids (ILs) form doubly hydrogen-bonded cationic dimers (c+=c+) despite the repulsive forces between ions of like charge and competing hydrogen bonds between cation and anion (c+–a−). This structural motif as known for formic acid, the archetype of double hydrogen bridges, is present in the solid state of the IL 1−(carboxymethyl)pyridinium bis(trifluoromethylsulfonyl)imide [HOOC−CH2−py][NTf2]. By means of quantum chemical calculations, we explored different hydrogen-bonded isomers of neutral (HOOC–(CH2)n–py+)2(NTf2−)2, single-charged (HOOC–(CH2)n–py+)2(NTf2−), and double-charged (HOOC– (CH2)n−py+)2 complexes for demonstrating the paradoxical case of “anti-electrostatic” hydrogen bonding (AEHB) between ions of like charge. For the pure doubly hydrogen-bonded cationic dimers (HOOC– (CH2)n−py+)2, we report robust kinetic stability for n = 1–4. At n = 5, hydrogen bonding and dispersion fully compensate for the repulsive Coulomb forces between the cations, allowing for the quantification of the two equivalent hydrogen bonds and dispersion interaction in the order of 58.5 and 11 kJmol−1, respectively. For n = 6–8, we calculated negative free energies for temperatures below 47, 80, and 114 K, respectively. Quantum cluster equilibrium (QCE) theory predicts the equilibria between cationic monomers and dimers by considering the intermolecular interaction between the species, leading to thermodynamic stability at even higher temperatures. We rationalize the H-bond characteristics of the cationic dimers by the natural bond orbital (NBO) approach, emphasizing the strong correlation between NBO-based and spectroscopic descriptors, such as NMR chemical shifts and vibrational frequencies.
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Affiliation(s)
- Loai Al-Sheakh
- Institut für Chemie, Abteilung für Physikalische Chemie, Universität Rostock, Dr.-Lorenz-Weg 2, 18059 Rostock, Germany; (L.A.-S.); (S.F.); (A.A.)
| | - Sebastian Fritsch
- Institut für Chemie, Abteilung für Physikalische Chemie, Universität Rostock, Dr.-Lorenz-Weg 2, 18059 Rostock, Germany; (L.A.-S.); (S.F.); (A.A.)
| | - Andreas Appelhagen
- Institut für Chemie, Abteilung für Physikalische Chemie, Universität Rostock, Dr.-Lorenz-Weg 2, 18059 Rostock, Germany; (L.A.-S.); (S.F.); (A.A.)
| | - Alexander Villinger
- Institut für Chemie, Abteilung für Anorganische Chemie, Universität Rostock, Albert-Einstein-Str. 3a, 18059 Rostock, Germany;
| | - Ralf Ludwig
- Institut für Chemie, Abteilung für Physikalische Chemie, Universität Rostock, Dr.-Lorenz-Weg 2, 18059 Rostock, Germany; (L.A.-S.); (S.F.); (A.A.)
- Department LL&M, University of Rostock, Albert-Einstein−Str. 25, 18059 Rostock, Germany
- Leibniz−Institut für Katalyse an der Universität Rostock e.V., Albert-Einstein−Str. 29a, 18059 Rostock, Germany
- Correspondence:
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8
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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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9
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Ludwig R. Towards thermodynamically stable anionic dimers with “anti-electrostatic” hydrogen bonds overcoming like-charge repulsion. J Mol Liq 2021. [DOI: 10.1016/j.molliq.2021.116882] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
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10
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Al Sheakh L, Niemann T, Villinger A, Stange P, Zaitsau DH, Strate A, Ludwig R. Three in One: The Versatility of Hydrogen Bonding Interaction in Halide Salts with Hydroxy-Functionalized Pyridinium Cations. Chemphyschem 2021; 22:1850-1856. [PMID: 34241946 PMCID: PMC8518508 DOI: 10.1002/cphc.202100424] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2021] [Revised: 07/08/2021] [Indexed: 11/28/2022]
Abstract
The paradigm of supramolecular chemistry relies on the delicate balance of noncovalent forces. Here we present a systematic approach for controlling the structural versatility of halide salts by the nature of hydrogen bonding interactions. We synthesized halide salts with hydroxy-functionalized pyridinium cations [HOCn Py]+ (n=2, 3, 4) and chloride, bromide and iodide anions, which are typically used as precursor material for synthesizing ionic liquids by anion metathesis reaction. The X-ray structures of these omnium halides show two types of hydrogen bonding: 'intra-ionic' H-bonds, wherein the anion interacts with the hydroxy group and the positively charged ring at the same cation, and 'inter-ionic' H-bonds, wherein the anion also interacts with the hydroxy group and the ring system but of different cations. We show that hydrogen bonding is controllable by the length of the hydroxyalkyl chain and the interaction strength of the anion. Some molten halide salts exhibit a third type of hydrogen bonding. IR spectra reveal elusive H-bonds between the OH groups of cations, showing interaction between ions of like charge. They are formed despite the repulsive interaction between the like-charged ions and compete with the favored cation-anion H-bonds. All types of H-bonding are analyzed by quantum chemical methods and the natural bond orbital approach, emphasizing the importance of charge transfer in these interactions. For simple omnium salts, we evidenced three distinct types of hydrogen bonds: Three in one!
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Affiliation(s)
- Loai Al Sheakh
- Universität RostockInstitut für Chemie, Abteilung für Physikalische ChemieDr.-Lorenz-Weg 218059RostockGermany
| | - Thomas Niemann
- Universität RostockInstitut für Chemie, Abteilung für Physikalische ChemieDr.-Lorenz-Weg 218059RostockGermany
| | - Alexander Villinger
- Institut für Chemie, Abteilung für Anorganische ChemieUniversität RostockAlbert-Einstein-Strasse 3a18059RostockGermany
| | - Peter Stange
- Universität RostockInstitut für Chemie, Abteilung für Physikalische ChemieDr.-Lorenz-Weg 218059RostockGermany
| | - Dzmitry H. Zaitsau
- Universität RostockInstitut für Chemie, Abteilung für Physikalische ChemieDr.-Lorenz-Weg 218059RostockGermany
- Department LL&MUniversity of RostockAlbert-Einstein-Str. 2518059RostockGermany
| | - Anne Strate
- Universität RostockInstitut für Chemie, Abteilung für Physikalische ChemieDr.-Lorenz-Weg 218059RostockGermany
- Department LL&MUniversity of RostockAlbert-Einstein-Str. 2518059RostockGermany
| | - Ralf Ludwig
- Universität RostockInstitut für Chemie, Abteilung für Physikalische ChemieDr.-Lorenz-Weg 218059RostockGermany
- Department LL&MUniversity of RostockAlbert-Einstein-Str. 2518059RostockGermany
- Leibniz-Institut für Katalyse an der Universität Rostock e.V.Albert-Einstein-Str. 29a18059RostockGermany
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11
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Neumann J, Ludwig R, Paschek D. Hydrogen Bonds between Ions of Opposite and Like Charge in Hydroxyl-Functionalized Ionic Liquids: an Exhaustive Examination of the Interplay between Global and Local Motions and Intermolecular Hydrogen Bond Lifetimes and Kinetics. J Phys Chem B 2021; 125:5132-5144. [PMID: 33971719 DOI: 10.1021/acs.jpcb.1c02756] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Hydroxyl-functionalized ionic liquids (ILs) represent a new interesting class of ILs where hydrogen bonds (HBs) play an important role: here, "typical" HBs between cations and anions (ca) are competing with "atypical" HBs connecting pairs of cations (cc). We study the equilibrium and kinetics of (cc) and (ca) HBs in 1-(n-hydroxyalkyl)-pyridinium bis(trifluoromethlysulfonyl)imide [HOCnPy][NTf2] ILs by means of molecular dynamics simulations. (cc) HBs are found to be between 0.96 and 3.76 kJ mol-1 stronger than their (ca) counterparts, depending on the alkyl chain length. HB lifetimes and kinetics are analyzed by means of HB population and reactive flux correlation functions. Essentially, four different HB lifetimes have to be considered, spanning about 3 orders of magnitude, each valid in its own right and each associated with different aspects of HB breaking and HB reformation. The long-time limiting behavior of the HB population correlation function is controlled by diffusion of the ions and can be quantitatively described by analytical expressions. The short-time HB behavior is tied to the localized dynamics of the hydroxyl group exploring its local solvation environment. A minimalist kinetic two-domain model is introduced to realistically describe the time evolution of the HB population correlation function for both (ca) and (cc) HBs over 5 orders of magnitude. By employing the reactive flux method, we determine the kinetics of HB breaking, unaffected by diffusion processes. We determine both, the ultrafast upper boundary and the average rate of HB breaking, allowing recrossing-events during the transient relaxation time period. For sufficiently long alkyl chains, all those computed HB lifetimes indicate a higher kinetic stability of (cc) HBs over (ca) HBs; for short chains, it is vice-versa.
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Affiliation(s)
- Jan Neumann
- Institut für Chemie, Abteilung Physikalische und Theoretische Chemie, Universität Rostock, Albert-Einstein-Str. 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.,Department Life, Light & Matter, Universität Rostock, Albert-Einstein-Str. 25, D-18059 Rostock, Germany.,Leibniz Institut für Katalyse an der Universität Rostock, Albert-Einstein-Str. 29a, D-18059 Rostock, Germany
| | - Dietmar Paschek
- Institut für Chemie, Abteilung Physikalische und Theoretische Chemie, Universität Rostock, Albert-Einstein-Str. 21, D-18059 Rostock, Germany
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12
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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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13
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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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14
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Lai A, Sahbaz Y, Ford L, Nguyen TH, Haque S, Williams HD, Benameur H, Scammells PJ, Porter CJH. Stabilising disproportionation of lipophilic ionic liquid salts in lipid-based formulations. Int J Pharm 2021; 597:120292. [PMID: 33581479 DOI: 10.1016/j.ijpharm.2021.120292] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2020] [Revised: 12/22/2020] [Accepted: 01/17/2021] [Indexed: 10/22/2022]
Abstract
Lipid based formulations (LBFs) can enhance oral bioavailability, however, their utility may be restricted by low drug loading in the formulation. Converting drugs to drug-ionic liquids (drug-ILs) or lipophilic salts can significantly increase lipid solubility but this approach is complicated in some cases by salt disproportionation, leading to a reduction in solubility and physical instability. Here we explore the physical stability of the weakly basic model drug, cinnarizine (CIN), when paired with a decanoate counterion (Dec) to form the drug-IL, cinnarizine decanoate (CIN.Dec). Consistent with published studies of salt disproportionation in aqueous solution, weakly acidic counterions such as Dec lead to the generation of drug-IL lipid solutions with pHs below pHmax. This leads to CIN deprotonation to the less soluble free base and precipitation. Subsequent studies however, show that these effects can be reversed by acidification of the formulation (either with excess decanoic acid or other lipid soluble acids), stimulating a pH shift to the salt plateau of CIN.Dec and the formation of stable lipid solutions of CIN.Dec. Altering formulation pH to more acidic conditions, therefore stabilises drug-ILs formed using weakly acidic lipophilic counterions, and is a viable method to promote formulation stability via inhibition of disproportionation of some drug-ILs.
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Affiliation(s)
- Anthony Lai
- Medicinal Chemistry, Monash Institute of Pharmaceutical Sciences, Monash University, 381 Royal Parade, Parkville, Victoria 3052 Australia; Drug Delivery, Disposition and Dynamics, Monash Institute of Pharmaceutical Sciences, Monash University, 381 Royal Parade, Parkville, Victoria 3052 Australia
| | - Yasemin Sahbaz
- Medicinal Chemistry, Monash Institute of Pharmaceutical Sciences, Monash University, 381 Royal Parade, Parkville, Victoria 3052 Australia; Drug Delivery, Disposition and Dynamics, Monash Institute of Pharmaceutical Sciences, Monash University, 381 Royal Parade, Parkville, Victoria 3052 Australia
| | - Leigh Ford
- Oral Drug Delivery Innovation, Chemical Division, Lonza Pharma Biotech & Nutrition, Melbourne Australia
| | - Tri-Hung Nguyen
- Drug Delivery, Disposition and Dynamics, Monash Institute of Pharmaceutical Sciences, Monash University, 381 Royal Parade, Parkville, Victoria 3052 Australia
| | - Shadabul Haque
- Drug Delivery, Disposition and Dynamics, Monash Institute of Pharmaceutical Sciences, Monash University, 381 Royal Parade, Parkville, Victoria 3052 Australia
| | - Hywel D Williams
- Oral Drug Delivery Innovation, Chemical Division, Lonza Pharma Biotech & Nutrition, Melbourne Australia
| | - Hassan Benameur
- Oral Drug Delivery Innovation, Chemical Division, Lonza Pharma Biotech & Nutrition, Strasbourg, France
| | - Peter J Scammells
- Medicinal Chemistry, Monash Institute of Pharmaceutical Sciences, Monash University, 381 Royal Parade, Parkville, Victoria 3052 Australia
| | - Christopher J H Porter
- Drug Delivery, Disposition and Dynamics, Monash Institute of Pharmaceutical Sciences, Monash University, 381 Royal Parade, Parkville, Victoria 3052 Australia; ARC Centre of Excellence in Convergent Bio-Nano Science and Technology, Monash University, 381 Royal Parade, Parkville, Victoria 3052 Australia.
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15
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Neumann J, Paschek D, Strate A, Ludwig R. Kinetics of Hydrogen Bonding between Ions with Opposite and Like Charges in Hydroxyl-Functionalized Ionic Liquids. J Phys Chem B 2021; 125:281-286. [PMID: 33356283 DOI: 10.1021/acs.jpcb.0c09278] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Hydrogen-bonded structures and their lifetimes in ionic liquids (ILs) are governed by the subtle balance between Coulomb interactions, hydrogen bonding, and dispersion forces. Despite the dominant Coulomb interaction, local and directional hydrogen bonds (HBs) can play an important role in the behavior of ILs. Compared to water, the archetype of hydrogen-bonded liquids, ILs have larger constituents and higher viscosities but are typically lacking a three-dimensional HB network. Hydroxyl-functionalized ionic liquids are even more special: regular HBs between cations and anions (ca) are accompanied by HBs between pairs of cations (cc). Recently, infrared (IR) measurements have suggested that the (cc) HBs are even stronger than their (ca) counterparts and their strength can be controlled via the hydroxyalkyl chain length. In this paper, we show by means of molecular dynamics (MD) simulations that the presence of HBs has a profound effect on the molecular mobility of the ions. We investigate the kinetic mechanism of hydrogen bonding in ILs and show that the lifetimes and hence the stability of (cc) HBs increase with the chain length, making them more stable than the respective (ca) HBs. The observed HB equilibrium can explain the peculiar chain length dependence of the relative molecular mobilities of the ions by a direct comparison between hydroxyl-functionalized ILs with their nonfunctionalized counterparts.
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Affiliation(s)
- Jan Neumann
- Institut für Chemie, Abteilung Physikalische und Theoretische Chemie, Universität Rostock, Dr.-Lorenz-Weg 2, D-18059 Rostock, Germany
| | - Dietmar Paschek
- Institut für Chemie, Abteilung Physikalische und Theoretische Chemie, Universität Rostock, Dr.-Lorenz-Weg 2, D-18059 Rostock, Germany
| | - Anne Strate
- Institut für Chemie, Abteilung Physikalische und Theoretische Chemie, Universität Rostock, Dr.-Lorenz-Weg 2, D-18059 Rostock, Germany.,Department Life, Light & Matter, Universität Rostock, Albert-Einstein-Straße 25, D-18059 Rostock, Germany
| | - Ralf Ludwig
- Institut für Chemie, Abteilung Physikalische und Theoretische Chemie, Universität Rostock, Dr.-Lorenz-Weg 2, D-18059 Rostock, Germany.,Department Life, Light & Matter, Universität Rostock, Albert-Einstein-Straße 25, D-18059 Rostock, Germany.,Leibniz Institut für Katalyse an der Universität Rostock, Albert-Einstein-Straße 29a, D-18059 Rostock, Germany
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16
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Zeng HJ, Khuu T, Chambreau SD, Boatz JA, Vaghjiani GL, Johnson MA. Ionic Liquid Clusters Generated from Electrospray Thrusters: Cold Ion Spectroscopic Signatures of Size-Dependent Acid-Base Interactions. J Phys Chem A 2020; 124:10507-10516. [PMID: 33284621 DOI: 10.1021/acs.jpca.0c07595] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
We determine the intramolecular distortions at play in the 2-hydroxyethylhydrazinium nitrate (HEHN) ionic liquid (IL) propellant, which presents the interesting case that the HEH+ cation has multiple sites (i.e., hydroxy, primary amine, and secondary ammonium groups) available for H-bonding with the nitrate anion. These interactions are quantified by analyzing the vibrational band patterns displayed by cold cationic clusters, (HEH+)n(NO3-)n-1, n = 2-6, which are obtained using IR photodissociation of the cryogenically cooled, mass-selected ions. The strong interaction involving partial proton transfer of the acidic N-H proton in HEH+ cation to the nitrate anion is strongly enhanced in the ternary n = 2 cluster but is suppressed with increasing cluster size. The cluster spectra recover the bands displayed by the bulk liquid by n = 5, thus establishing the minimum domain required to capture this aspect of macroscopic behavior.
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Affiliation(s)
- Helen J Zeng
- Sterling Chemistry Laboratory, Yale University, New Haven, Connecticut 06520, United States
| | - Thien Khuu
- Sterling Chemistry Laboratory, Yale University, New Haven, Connecticut 06520, United States
| | - Steven D Chambreau
- Jacobs Technology, Inc., Air Force Research Laboratory, AFRL/RQRP, Edwards Air Force Base, California 93524, United States
| | - Jerry A Boatz
- Propellants Branch, Rocket Propulsion Division, Aerospace Systems Directorate, Air Force Research Laboratory, AFRL/RQRP, Edwards Air Force Base, California 93524, United States
| | - Ghanshyam L Vaghjiani
- In-Space Propulsion Branch, Rocket Propulsion Division, Aerospace Systems Directorate, Air Force Research Laboratory, AFRL/RQRP, Edwards Air Force Base, California 93524, United States
| | - Mark A Johnson
- Sterling Chemistry Laboratory, Yale University, New Haven, Connecticut 06520, United States
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17
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Philipp JK, Fritsch S, Ludwig R. Cyclic Octamer of Hydroxyl-functionalized Cations with Net Charge Q=+8e Kinetically Stabilized by a 'Molecular Island' of Cooperative Hydrogen Bonds. Chemphyschem 2020; 21:2411-2416. [PMID: 32845043 PMCID: PMC7702028 DOI: 10.1002/cphc.202000681] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2020] [Revised: 08/20/2020] [Indexed: 11/07/2022]
Abstract
Cyclic octamers are well-known structural motifs in chemistry, biology and physics. These include covalently bound cyclic octameric sulphur, cylic octa-alkanes, cyclo-octameric peptides as well as hydrogen-bonded ring clusters of alcohols. In this work, we show that even calculated cyclic octamers of hydroxy-functionalized pyridinium cations with a net charge Q=+8e are kinetically stable. Eight positively charged cations are kept together by hydrogen bonding despite the strong Coulomb repulsive forces. Sufficiently long hydroxy-octyl chains prevent "Coulomb explosion" by increasing the distance between the positive charges at the pyridinium rings, reducing the Coulomb repulsion and thus strengthen hydrogen bonds between the OH groups. The eightfold positively charged cyclic octamer shows spectroscopic properties similar to those obtained for hydrogen-bonded neutral cyclic octamers of methanol. Thus, the area of the hydrogen bonded OH ring represents a 'molecular island' within an overall cationic environment. Although not observable, the spectroscopic properties and the correlated NBO parameters of the calculated cationic octamer support the detection of smaller cationic clusters in ionic liquids, which we observed despite the competition with ion pairs wherein attractive Coulomb forces enhance hydrogen bonding between cation and anion.
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Affiliation(s)
- Jule Kristin Philipp
- Universität RostockInstitut für ChemieAbteilung Physikalische und Theoretische ChemieDr.-Lorenz-Weg 218059RostockGermany
| | - Sebastian Fritsch
- Universität RostockInstitut für ChemieAbteilung Physikalische und Theoretische ChemieDr.-Lorenz-Weg 218059RostockGermany
| | - Ralf Ludwig
- Universität RostockInstitut für ChemieAbteilung Physikalische und Theoretische ChemieDr.-Lorenz-Weg 218059RostockGermany
- Universität RostockDepartment LL&MAlbert-Einstein-Str. 2518059RostockGermany
- Leibniz-Institut für Katalyse an der Universität Rostock e.V.Albert-Einstein-Str. 29a18059RostockGermany
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18
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Philipp JK, Ludwig R. Clusters of Hydroxyl-Functionalized Cations Stabilized by Cooperative Hydrogen Bonds: The Role of Polarizability and Alkyl Chain Length. Molecules 2020; 25:molecules25214972. [PMID: 33121087 PMCID: PMC7662246 DOI: 10.3390/molecules25214972] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2020] [Revised: 10/22/2020] [Accepted: 10/24/2020] [Indexed: 01/08/2023] Open
Abstract
We explore quantum chemical calculations for studying clusters of hydroxyl-functionalized cations kinetically stabilized by hydrogen bonding despite strongly repulsive electrostatic forces. In a comprehensive study, we calculate clusters of ammonium, piperidinium, pyrrolidinium, imidazolium, pyridinium, and imidazolium cations, which are prominent constituents of ionic liquids. All cations are decorated with hydroxy-alkyl chains allowing H-bond formation between ions of like charge. The cluster topologies comprise linear and cyclic clusters up to the size of hexamers. The ring structures exhibit cooperative hydrogen bonds opposing the repulsive Coulomb forces and leading to kinetic stability of the clusters. We discuss the importance of hydrogen bonding and dispersion forces for the stability of the differently sized clusters. We find the largest clusters when hydrogen bonding is maximized in cyclic topologies and dispersion interaction is properly taken into account. The kinetic stability of the clusters with short-chained cations is studied for the different types of cations ranging from hard to polarizable or exhibiting additional functional groups such as the acidic C(2)-H position in the imidazolium-based cation. Increasing the alkyl chain length, the cation effect diminishes and the kinetic stability is exclusively governed by the alkyl chain tether increasing the distance between the positively charged rings of the cations. With adding the counterion tetrafluoroborate (BF4−) to the cationic clusters, the binding energies immediately switch from strongly positive to strongly negative. In the neutral clusters, the OH functional groups of the cations can interact either with other cations or with the anions. The hexamer cluster with the cyclic H-bond motive and “released” anions is almost as stable as the hexamer built by H-bonded ion pairs exclusively, which is in accord with recent IR spectra of similar ionic liquids detecting both types of hydrogen bonding. For the cationic and neutral clusters, we discuss geometric and spectroscopic properties as sensitive probes of opposite- and like-charge interaction. Finally, we show that NMR proton chemical shifts and deuteron quadrupole coupling constants can be related to each other, allowing to predict properties which are not easily accessible by experiment.
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Affiliation(s)
- Jule K. Philipp
- Institut für Chemie, Abteilung Physikalische und Theoretische Chemie, Universität Rostock, 18059 Rostock, Germany;
| | - Ralf Ludwig
- Institut für Chemie, Abteilung Physikalische und Theoretische Chemie, Universität Rostock, 18059 Rostock, Germany;
- Department Life, Light & Matter, Universität Rostock, Albert-Einstein-Str. 25, 18059 Rostock, Germany
- Leibniz-Institut für Katalyse an der Universität Rostock e.V., Albert-Einstein-Str. 29a, 18059 Rostock, Germany
- Correspondence: ; Tel.: +49-381-498-6517
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19
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Abstract
The extent to which cations and anions in ionic liquids (ILs) and ionic liquid solutions are dissociated is of both fundamental scientific interest and practical importance because ion dissociation has been shown to impact viscosity, density, surface tension, volatility, solubility, chemical reactivity, and many other important chemical and physical properties. When mixed with solvents, ionic liquids provide the unique opportunity to investigate ion dissociation from infinite dilution in the solvent to a completely solvent-free state, even at ambient conditions. The most common way to estimate ion dissociation in ILs and IL solutions is by comparing the molar conductivity determined from ionic conductivity measurements such as electrochemical impedance spectroscopy (EIS) (which measure the movement of only the charged, i.e., dissociated, ions) with the molar conductivity calculated from ion diffusivities measured by pulse field gradient nuclear magnetic resonance spectroscopy (PFG-NMR, which gives movement of all of the ions). Because the NMR measurements are time-consuming, the number of ILs and IL solutions investigated by this method is relatively limited. We have shown that use of the Stokes-Einstein equation with estimates of the effective ion Stokes radii allows ion dissociation to be calculated from easily measured density, viscosity, and ionic conductivity data (ρ, η, λ), which is readily available in the literature for a much larger number of pure ILs and IL solutions. Therefore, in this review, we present values of ion dissociation for ILs and IL solutions (aqueous and nonaqueous) determined by both the traditional molar conductivity/PFG-NMR method and the ρ, η, λ method. We explore the effect of cation and anion alkyl chain length, structure, and interaction motifs of the cation and anion, temperature, and the strength of the solvent in IL solutions.
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Affiliation(s)
- Oscar Nordness
- McKetta Department of Chemical Engineering, University of Texas at Austin, Austin, Texas 78712, United States
| | - Joan F Brennecke
- McKetta Department of Chemical Engineering, University of Texas at Austin, Austin, Texas 78712, United States
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20
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Khudozhitkov AE, Niemann T, Stange P, Donoshita M, Stepanov AG, Kitagawa H, Kolokolov DI, Ludwig R. Freezing the Motion in Hydroxy-Functionalized Ionic Liquids-Temperature Dependent NMR Deuteron Quadrupole Coupling Constants for Two Types of Hydrogen Bonds Far below the Glass Transition. J Phys Chem Lett 2020; 11:6000-6006. [PMID: 32640795 DOI: 10.1021/acs.jpclett.0c01731] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
We measured the deuteron quadrupole coupling constants (DQCCs) for hydroxy-functionalized ionic liquids (ILs) with varying alkyl chain length over the temperature range between 60 and 200 K by means of solid-state NMR spectroscopy. For all temperatures, the 2H spectra show two DQCCs representing different types of hydrogen bonds. Higher values, ranging from 220 to 250 kHz, indicate weaker hydrogen bonds between cation and anion (c-a), and lower values varying from 165 to 210 kHz result from stronger hydrogen bonds between the OD groups of cations (c-c), in agreement with recent observations in infrared, neutron diffraction, and NMR studies. We observed different temperature dependencies for (c-a) and (c-c) hydrogen bonding. From the static pattern of the 2H spectra at the lowest temperatures, we derived the true DQCCs being up to 20 kHz larger than recently reported values measured at the glass transition temperature. We were able to freeze the librational motions of the hydrogen bonds in the ILs. The temperature dependence of the (c-a) and (c-c) cluster populations in the glassy state is opposite to that observed in the liquid state, partly anticipating the behavior of ILs tending to crystallize.
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Affiliation(s)
- Alexander E Khudozhitkov
- Boreskov Institute of Catalysis, Siberian Branch of Russian Academy of Sciences, Prospekt Akademika Lavrentieva 5, Novosibirsk 630090, Russia
- Novosibirsk State University, Pirogova Street 2, Novosibirsk 630090, Russia
| | - Thomas Niemann
- Abteilung für Physikalische Chemie, Institut für Chemie, Universität Rostock, Dr.-Lorenz-Weg 2, 18059 Rostock, Germany
| | - Peter Stange
- Abteilung für Physikalische Chemie, Institut für Chemie, Universität Rostock, Dr.-Lorenz-Weg 2, 18059 Rostock, Germany
| | - Masaki Donoshita
- Division of Chemistry, Graduate School of Science, Kyoto University, Kitashirakawa-Oiwakecho, Sakyo-ku, Kyoto 606-8502, Japan
| | - Alexander G Stepanov
- Boreskov Institute of Catalysis, Siberian Branch of Russian Academy of Sciences, Prospekt Akademika Lavrentieva 5, Novosibirsk 630090, Russia
- Novosibirsk State University, Pirogova Street 2, Novosibirsk 630090, Russia
| | - Hiroshi Kitagawa
- Division of Chemistry, Graduate School of Science, Kyoto University, Kitashirakawa-Oiwakecho, Sakyo-ku, Kyoto 606-8502, Japan
| | - Daniil I Kolokolov
- Boreskov Institute of Catalysis, Siberian Branch of Russian Academy of Sciences, Prospekt Akademika Lavrentieva 5, Novosibirsk 630090, Russia
- Novosibirsk State University, Pirogova Street 2, Novosibirsk 630090, Russia
| | - Ralf Ludwig
- Abteilung für Physikalische Chemie, Institut für Chemie, Universität Rostock, 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
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21
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Wang YL, Li B, Sarman S, Mocci F, Lu ZY, Yuan J, Laaksonen A, Fayer MD. Microstructural and Dynamical Heterogeneities in Ionic Liquids. Chem Rev 2020; 120:5798-5877. [PMID: 32292036 PMCID: PMC7349628 DOI: 10.1021/acs.chemrev.9b00693] [Citation(s) in RCA: 189] [Impact Index Per Article: 47.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2019] [Indexed: 12/11/2022]
Abstract
Ionic liquids (ILs) are a special category of molten salts solely composed of ions with varied molecular symmetry and charge delocalization. The versatility in combining varied cation-anion moieties and in functionalizing ions with different atoms and molecular groups contributes to their peculiar interactions ranging from weak isotropic associations to strong, specific, and anisotropic forces. A delicate interplay among intra- and intermolecular interactions facilitates the formation of heterogeneous microstructures and liquid morphologies, which further contributes to their striking dynamical properties. Microstructural and dynamical heterogeneities of ILs lead to their multifaceted properties described by an inherent designer feature, which makes ILs important candidates for novel solvents, electrolytes, and functional materials in academia and industrial applications. Due to a massive number of combinations of ion pairs with ion species having distinct molecular structures and IL mixtures containing varied molecular solvents, a comprehensive understanding of their hierarchical structural and dynamical quantities is of great significance for a rational selection of ILs with appropriate properties and thereafter advancing their macroscopic functionalities in applications. In this review, we comprehensively trace recent advances in understanding delicate interplay of strong and weak interactions that underpin their complex phase behaviors with a particular emphasis on understanding heterogeneous microstructures and dynamics of ILs in bulk liquids, in mixtures with cosolvents, and in interfacial regions.
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Affiliation(s)
- Yong-Lei Wang
- Department
of Materials and Environmental Chemistry, Arrhenius Laboratory, Stockholm University, SE-106 91 Stockholm, Sweden
| | - Bin Li
- School
of Chemical Engineering and Technology, Sun Yat-sen University, Zhuhai 519082, P. R. China
| | - Sten Sarman
- Department
of Materials and Environmental Chemistry, Arrhenius Laboratory, Stockholm University, SE-106 91 Stockholm, Sweden
| | - Francesca Mocci
- Department
of Chemical and Geological Sciences, University
of Cagliari, I-09042 Monserrato, Italy
| | - Zhong-Yuan Lu
- State
Key Laboratory of Supramolecular Structure and Materials, Institute
of Theoretical Chemistry, Jilin University, Changchun 130021, P. R. China
| | - Jiayin Yuan
- Department
of Materials and Environmental Chemistry, Arrhenius Laboratory, Stockholm University, SE-106 91 Stockholm, Sweden
| | - Aatto Laaksonen
- Department
of Materials and Environmental Chemistry, Arrhenius Laboratory, Stockholm University, SE-106 91 Stockholm, Sweden
- State
Key Laboratory of Materials-Oriented and Chemical Engineering, Nanjing Tech University, Nanjing 210009, P. R. China
- Centre of
Advanced Research in Bionanoconjugates and Biopolymers, Petru Poni Institute of Macromolecular Chemistry Aleea Grigore Ghica-Voda, 41A, 700487 Iasi, Romania
- Department
of Engineering Sciences and Mathematics, Division of Energy Science, Luleå University of Technology, SE-97187 Luleå, Sweden
| | - Michael D. Fayer
- Department
of Chemistry, Stanford University, Stanford, California 94305, United States
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22
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Structural Features of Triethylammonium Acetate through Molecular Dynamics. Molecules 2020; 25:molecules25061432. [PMID: 32245229 PMCID: PMC7146455 DOI: 10.3390/molecules25061432] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2020] [Accepted: 03/19/2020] [Indexed: 12/13/2022] Open
Abstract
I have explored the structural features and the dynamics of triethylammonium acetate by means of semi-empirical (density functional tight binding, DFTB) molecular dynamics. I find that the results from the present simulations agree with recent experimental determinations with only few minor differences in the structural interpretation. A mixture of triethylamine and acetic acid does not form an ionic liquid, but gives rise to a very complex system where ionization is only a partial process affecting only few molecules (1 over 4 experimentally). I have also found that the few ionic couples are stable and remain mainly embedded inside the AcOH neutral moiety.
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23
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Patrick AL. Electrospray ionization enters the final frontier: Mass spectrometry's role in understanding electrospray thrusters and their plumes. RAPID COMMUNICATIONS IN MASS SPECTROMETRY : RCM 2020; 34:e8587. [PMID: 31509305 DOI: 10.1002/rcm.8587] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/03/2019] [Accepted: 09/02/2019] [Indexed: 06/10/2023]
Abstract
Electrospray thrusters using ionic liquid (IL)-based propellants are quickly gaining popularity in spacecraft design. Mass spectrometry is especially well-suited to provide important knowledge on the fundamentals of how these systems work and on evaluating their efficiencies and impacts, given that the operating principles of electrospray thrusters closely mimics the mass spectrometry experiment - in both ions are generated by electrospray and then enter a vacuum. Here, electrospray thruster technology and IL-based propellants are briefly introduced. This introduction is then followed by a discussion of mass spectrometry's current contribution to the study of IL-based electrospray thrusters - with a focus on electrospray, dissociation, and spectroscopy studies - and a brief discussion of areas ripe for immediate contributions from the mass spectrometry community.
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Affiliation(s)
- Amanda L Patrick
- Department of Chemistry, Mississippi State University, Mississippi State, MI, 39762, USA
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24
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Zeng HJ, Menges FS, Niemann T, Strate A, Ludwig R, Johnson MA. Chain Length Dependence of Hydrogen Bond Linkages between Cationic Constituents in Hydroxy-Functionalized Ionic Liquids: Tracking Bulk Behavior to the Molecular Level with Cold Cluster Ion Spectroscopy. J Phys Chem Lett 2020; 11:683-688. [PMID: 31899639 DOI: 10.1021/acs.jpclett.9b03359] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Hydroxy functionalization of cations in ionic liquids (ILs) can lead to formation of contacts between their OH groups [so-called (c-c) interactions]. One class of these linkages involves cooperatively enhanced hydrogen bonds to anionic partners that are sufficiently strong to overcome the repulsion between two positively charged centers. Herein, we clarify how the propensity for the formation of (c-c) contacts depends on the alkyl chain length between two cationic rings and their OH groups by analyzing the temperature-dependent IR spectra of bulk ILs as well as the vibrational predissociation spectra of ∼35 K complexes comprised of two cations and one anion. This study compares the behavior of two cationic derivatives with ethyl and propyl chains complexed with two different anions: bis(trifluoromethylsulfonyl)imide and tetrafluoroborate. Only the bulk ILs with the longer chain propyl derivative [HPMPip+ = 1-(3-hydroxypropyl)-1-methylpiperidinium] display (c-c) interactions. Molecular-level aspects of this docking arrangement are revealed by analyzing the OH stretching fundamentals displayed by the ternary complexes.
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Affiliation(s)
- Helen J Zeng
- Sterling Chemistry Laboratory , Yale University , New Haven , Connecticut 06520 , United States
| | - Fabian S Menges
- Sterling Chemistry Laboratory , Yale University , New Haven , Connecticut 06520 , United States
| | - Thomas Niemann
- Department of Chemistry , University of Rostock , 18059 Rostock , Germany
- Department Life, Light & Matter , University of Rostock , Albert-Einstein-Strasse 25 , 18059 Rostock , Germany
| | - Anne Strate
- Department of Chemistry , University of Rostock , 18059 Rostock , Germany
- Department Life, Light & Matter , University of Rostock , Albert-Einstein-Strasse 25 , 18059 Rostock , Germany
| | - Ralf Ludwig
- Department of Chemistry , University of Rostock , 18059 Rostock , Germany
- Department Life, Light & Matter , University of Rostock , Albert-Einstein-Strasse 25 , 18059 Rostock , Germany
- Leibniz-Institut für Katalyse e.V. , Albert-Einstein-Strasse 29a , 18059 Rostock , Germany
| | - Mark A Johnson
- Sterling Chemistry Laboratory , Yale University , New Haven , Connecticut 06520 , United States
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25
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Niemann T, Zaitsau DH, Strate A, Stange P, Ludwig R. Controlling "like-likes-like" charge attraction in hydroxy-functionalized ionic liquids by polarizability of the cations, interaction strength of the anions and varying alkyl chain length. Phys Chem Chem Phys 2020; 22:2763-2774. [PMID: 31951236 DOI: 10.1039/c9cp06481h] [Citation(s) in RCA: 24] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
We provide comprehensive understanding of "like-likes-like" charge attraction in hydroxy-functionalized ionic liquids (ILs) by means of infrared spectroscopy (IR), quantum chemistry and differential scanning calorimetry (DSC). We show that hydrogen bonding between cation and cation (c-c) is possible despite the repulsive forces between ions of like charge. Already at room temperature, the (c-c) hydrogen bonds can compete with the regular Coulomb-enhanced hydrogen bonds between cation and anion (c-a). For a large set of well-selected ILs, we show that "like-charge attraction" between the OH-functionalized cations is controllable by the polarizability of the cation, the interaction strength of the anion and the length of the hydroxyalkyl chain. In particular, we clarify whether tethering the OH group away from the positive charge center of the cationic ring with longer hydroxyalkyl chains compensates for unfavourable cation/anion combinations with respect to (c-c) cluster formation. For that purpose, we synthesized and characterized twelve ionic liquids including the differently polarizable cations, 1-(n-hydroxyalkyl)-1-methylpiperidinium [HOCnMPip]+ and 1-(n-hydroxyalkyl)-pyridinium [HOCnPy]+, as well as the weakly and strongly interacting anions, bis(trifluoromethanesulfonyl)imide [NTf2]- and methanesulfonate [OMs]-, respectively. On top, we varied the hydroxyalkyl chain length (HOCn) (n = 2-5). We systematically show how these three molecular ion parameters affect like-charge attraction. The use of polarizable cations, weakly interacting anions, and long alkyl chain tethers results in (c-c) clustering already at room temperature. Kinetic trapping is not a prerequisite for the existence of (c-c) cluster species in ILs. Moreover, we demonstrate that micro structuring affects macroscopic behavior of this type of ILs. We observed that substantial (c-c) interaction prevents ILs from crystallizing. Instead, these ILs supercool and finally form a glass.
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Affiliation(s)
- Thomas Niemann
- Universität Rostock, Institut für Chemie, Abteilung für Physikalische Chemie, Dr-Lorenz-Weg 2, 18059, Rostock, Germany.
| | - Dzmitry H Zaitsau
- Universität Rostock, Institut für Chemie, Abteilung für Physikalische Chemie, Dr-Lorenz-Weg 2, 18059, Rostock, Germany. and Department LL&M, University of Rostock, Albert-Einstein-Str. 25, 18059, Rostock, Germany
| | - Anne Strate
- Universität Rostock, Institut für Chemie, Abteilung für Physikalische Chemie, Dr-Lorenz-Weg 2, 18059, Rostock, Germany. and Department LL&M, University of Rostock, Albert-Einstein-Str. 25, 18059, Rostock, Germany
| | - Peter Stange
- Universität Rostock, Institut für Chemie, Abteilung für Physikalische Chemie, Dr-Lorenz-Weg 2, 18059, Rostock, Germany.
| | - Ralf Ludwig
- Universität Rostock, Institut für Chemie, Abteilung für Physikalische Chemie, Dr-Lorenz-Weg 2, 18059, Rostock, Germany. and Department LL&M, University of Rostock, Albert-Einstein-Str. 25, 18059, Rostock, Germany and Leibniz-Institut für Katalyse an der Universität Rostock e.V., Albert-Einstein-Str. 29a, 18059 Rostock, Germany
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26
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Strate A, Neumann J, Niemann T, Stange P, Khudozhitkov AE, Stepanov AG, Paschek D, Kolokolov DI, Ludwig R. Counting cations involved in cationic clusters of hydroxy-functionalized ionic liquids by means of infrared and solid-state NMR spectroscopy. Phys Chem Chem Phys 2020; 22:6861-6867. [PMID: 32202267 DOI: 10.1039/d0cp00303d] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
Sensitive probe of like-charge attraction: analyzing infrared spectra allows counting the number of cations involved in clusters of opposite (c–a) and like-charged (c–c) ions in ionic liquids. This approach is also applicable to molecular liquids.
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Affiliation(s)
- Anne Strate
- Universität Rostock
- Institut für Chemie
- Abteilung für Physikalische Chemie
- 18059 Rostock
- Germany
| | - Jan Neumann
- Universität Rostock
- Institut für Chemie
- Abteilung für Physikalische Chemie
- 18059 Rostock
- Germany
| | - Thomas Niemann
- Universität Rostock
- Institut für Chemie
- Abteilung für Physikalische Chemie
- 18059 Rostock
- Germany
| | - Peter Stange
- Universität Rostock
- Institut für Chemie
- Abteilung für Physikalische Chemie
- 18059 Rostock
- Germany
| | - Alexander E. Khudozhitkov
- Boreskov Institute of Catalysis
- Siberian Branch of Russian Academy of Sciences
- Novosibirsk 630090
- Russia
- Novosibirsk State University
| | - Alexander G. Stepanov
- Boreskov Institute of Catalysis
- Siberian Branch of Russian Academy of Sciences
- Novosibirsk 630090
- Russia
- Novosibirsk State University
| | - Dietmar Paschek
- Universität Rostock
- Institut für Chemie
- Abteilung für Physikalische Chemie
- 18059 Rostock
- Germany
| | - Daniil I. Kolokolov
- Boreskov Institute of Catalysis
- Siberian Branch of Russian Academy of Sciences
- Novosibirsk 630090
- Russia
- Novosibirsk State University
| | - Ralf Ludwig
- Universität Rostock
- Institut für Chemie
- Abteilung für Physikalische Chemie
- 18059 Rostock
- Germany
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27
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Zeng HJ, Menges FS, Johnson MA. Comment on “C–D Vibration at C2 Position of Imidazolium Cation as a Probe of the Ionic Liquid Microenvironment”. J Phys Chem A 2019; 124:755-756. [DOI: 10.1021/acs.jpca.9b10728] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Helen J. Zeng
- Sterling Chemistry Laboratory, Yale University, New Haven, Connecticut 06520, United States
| | - Fabian S. Menges
- Sterling Chemistry Laboratory, Yale University, New Haven, Connecticut 06520, United States
| | - Mark A. Johnson
- Sterling Chemistry Laboratory, Yale University, New Haven, Connecticut 06520, United States
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28
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Niemann T, Li H, Warr GG, Ludwig R, Atkin R. Influence of Hydrogen Bonding between Ions of Like Charge on the Ionic Liquid Interfacial Structure at a Mica Surface. J Phys Chem Lett 2019; 10:7368-7373. [PMID: 31713427 DOI: 10.1021/acs.jpclett.9b03007] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Ionic liquids (ILs) have attracted increasing interest in science and technology because of their remarkable properties, which can be tuned via varying ion structures to control the relative strengths of Coulomb interactions, hydrogen bonding (H-bonding), and dispersion forces. Here we use atomic force microscopy to probe the interfacial nanostructures of hydroxy functionalized ILs at negatively charged mica surfaces. H-bonding between hydroxy functionalized cations (c-c) produces cation clusters and a stronger interfacial nanostructure. H-bond stabilized cation clusters form despite opposing electrostatic repulsions between charge groups, cation-anion (c-a) electrostatic attractions, and (c-a) H-bonds. Comparison of ILs with and without OH functionalized cations shows directional H-bonding enhances interfacial structure more strongly than the dispersion forces between alkyl groups. These findings reveal a new means of controlling IL interfacial nanostructure via H-bonding between like-charged ions, which impact diverse areas including electrochemical charge storage (batteries and catalysis), electrodeposition, lubrication, etc.
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Affiliation(s)
- Thomas Niemann
- Institut für Chemie, Abteilung für Physikalische Chemie , Universität Rostock , Dr.-Lorenz-Weg 2 , 18059 Rostock , Germany
- Department LL&M , University of Rostock , Albert-Einstein-Str. 25 , 18059 Rostock , Germany
| | - Hua Li
- School of Molecular Sciences , The University of Western Australia , Perth , Western Australia 6009 , Australia
| | - Gregory G Warr
- School of Chemistry and Sydney Nano Institute , The University of Sydney , Camperdown , NSW 2006 , Australia
| | - Ralf Ludwig
- Institut für Chemie, Abteilung für Physikalische Chemie , Universität Rostock , Dr.-Lorenz-Weg 2 , 18059 Rostock , Germany
- Department LL&M , University of Rostock , Albert-Einstein-Str. 25 , 18059 Rostock , Germany
- Leibniz-Institut für Katalyse an der Universität Rostock e.V. , Albert-Einstein-Str. 29a , 18059 Rostock , Germany
| | - Rob Atkin
- School of Molecular Sciences , The University of Western Australia , Perth , Western Australia 6009 , Australia
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29
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Khudozhitkov AE, Neumann J, Niemann T, Zaitsau D, Stange P, Paschek D, Stepanov AG, Kolokolov DI, Ludwig R. Hydrogen Bonding Between Ions of Like Charge in Ionic Liquids Characterized by NMR Deuteron Quadrupole Coupling Constants—Comparison with Salt Bridges and Molecular Systems. Angew Chem Int Ed Engl 2019. [DOI: 10.1002/ange.201912476] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Affiliation(s)
- Alexander E. Khudozhitkov
- Boreskov Institute of CatalysisSiberian Branch of Russian Academy of Sciences Prospekt Akademika Lavrentieva 5 Novosibirsk 630090 Russia
- Novosibirsk State University Pirogova Street 2 Novosibirsk 630090 Russia
| | - Jan Neumann
- Universität RostockInstitut für ChemieAbteilung für Physikalische Chemie Dr.-Lorenz-Weg 2 18059 Rostock Germany
| | - Thomas Niemann
- Universität RostockInstitut für ChemieAbteilung für Physikalische Chemie Dr.-Lorenz-Weg 2 18059 Rostock Germany
| | - Dzmitry Zaitsau
- Department LL&MUniversity of Rostock Albert-Einstein-Str. 25 18059 Rostock Germany
| | - Peter Stange
- Universität RostockInstitut für ChemieAbteilung für Physikalische Chemie Dr.-Lorenz-Weg 2 18059 Rostock Germany
| | - Dietmar Paschek
- Universität RostockInstitut für ChemieAbteilung für Physikalische Chemie Dr.-Lorenz-Weg 2 18059 Rostock Germany
| | - Alexander G. Stepanov
- Boreskov Institute of CatalysisSiberian Branch of Russian Academy of Sciences Prospekt Akademika Lavrentieva 5 Novosibirsk 630090 Russia
- Novosibirsk State University Pirogova Street 2 Novosibirsk 630090 Russia
| | - Daniil I. Kolokolov
- Boreskov Institute of CatalysisSiberian Branch of Russian Academy of Sciences Prospekt Akademika Lavrentieva 5 Novosibirsk 630090 Russia
- Novosibirsk State University Pirogova Street 2 Novosibirsk 630090 Russia
| | - Ralf Ludwig
- Universität RostockInstitut für ChemieAbteilung für Physikalische Chemie Dr.-Lorenz-Weg 2 18059 Rostock Germany
- Department LL&MUniversity of Rostock Albert-Einstein-Str. 25 18059 Rostock Germany
- Leibniz-Institut für Katalyse an der Universität Rostock e.V. Albert-Einstein-Str. 29a 18059 Rostock Germany
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30
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Khudozhitkov AE, Neumann J, Niemann T, Zaitsau D, Stange P, Paschek D, Stepanov AG, Kolokolov DI, Ludwig R. Hydrogen Bonding Between Ions of Like Charge in Ionic Liquids Characterized by NMR Deuteron Quadrupole Coupling Constants-Comparison with Salt Bridges and Molecular Systems. Angew Chem Int Ed Engl 2019; 58:17863-17871. [PMID: 31588622 PMCID: PMC6899581 DOI: 10.1002/anie.201912476] [Citation(s) in RCA: 32] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2019] [Indexed: 11/23/2022]
Abstract
We present deuteron quadrupole coupling constants (DQCC) for hydroxyl‐functionalized ionic liquids (ILs) in the crystalline or glassy states characterizing two types of hydrogen bonding: The regular Coulomb‐enhanced hydrogen bonds between cation and anion (c–a), and the unusual hydrogen bonds between cation and cation (c–c), which are present despite repulsive Coulomb forces. We measure these sensitive probes of hydrogen bonding by means of solid‐state NMR spectroscopy. The DQCCs of (c–a) ion pairs and (c–c) H‐bonds are compared to those of salt bridges in supramolecular complexes and those present in molecular liquids. At low temperatures, the (c–c) species successfully compete with the (c–a) ion pairs and dominate the cluster populations. Equilibrium constants obtained from molecular‐dynamics (MD) simulations show van't Hoff behavior with small transition enthalpies between the differently H‐bonded species. We show that cationic‐cluster formation prevents these ILs from crystallizing. With cooling, the (c–c) hydrogen bonds persist, resulting in supercooling and glass formation.
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Affiliation(s)
- Alexander E Khudozhitkov
- Boreskov Institute of Catalysis, Siberian Branch of Russian Academy of Sciences, Prospekt Akademika Lavrentieva 5, Novosibirsk, 630090, Russia.,Novosibirsk State University, Pirogova Street 2, Novosibirsk, 630090, Russia
| | - Jan Neumann
- Universität Rostock, Institut für Chemie, Abteilung für Physikalische Chemie, Dr.-Lorenz-Weg 2, 18059, Rostock, Germany
| | - Thomas Niemann
- Universität Rostock, Institut für Chemie, Abteilung für Physikalische Chemie, Dr.-Lorenz-Weg 2, 18059, Rostock, Germany
| | - Dzmitry Zaitsau
- Department LL&M, University of Rostock, Albert-Einstein-Str. 25, 18059, Rostock, Germany
| | - Peter Stange
- Universität Rostock, Institut für Chemie, Abteilung für Physikalische Chemie, Dr.-Lorenz-Weg 2, 18059, Rostock, Germany
| | - Dietmar Paschek
- Universität Rostock, Institut für Chemie, Abteilung für Physikalische Chemie, Dr.-Lorenz-Weg 2, 18059, Rostock, Germany
| | - Alexander G Stepanov
- Boreskov Institute of Catalysis, Siberian Branch of Russian Academy of Sciences, Prospekt Akademika Lavrentieva 5, Novosibirsk, 630090, Russia.,Novosibirsk State University, Pirogova Street 2, Novosibirsk, 630090, Russia
| | - Daniil I Kolokolov
- Boreskov Institute of Catalysis, Siberian Branch of Russian Academy of Sciences, Prospekt Akademika Lavrentieva 5, Novosibirsk, 630090, Russia.,Novosibirsk State University, Pirogova Street 2, Novosibirsk, 630090, Russia
| | - 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-Str. 25, 18059, Rostock, Germany.,Leibniz-Institut für Katalyse an der Universität Rostock e.V., Albert-Einstein-Str. 29a, 18059, Rostock, Germany
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31
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Niemann T, Neumann J, Stange P, Gärtner S, Youngs TGA, Paschek D, Warr GG, Atkin R, Ludwig R. Die zweigesichtige Natur der Wasserstoffbrückenbindung in hydroxylfunktionalisierten ionischen Flüssigkeiten, offenbart durch Neutronendiffraktometrie und Molekulardynamik‐Simulation. Angew Chem Int Ed Engl 2019. [DOI: 10.1002/ange.201904712] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Affiliation(s)
- Thomas Niemann
- Universität Rostock Institut für Chemie Abteilung für Physikalische Chemie Dr.-Lorenz-Weg 2 18059 Rostock Deutschland
| | - Jan Neumann
- Universität Rostock Institut für Chemie Abteilung für Physikalische Chemie Albert-Einstein-Str. 21 18059 Rostock Deutschland
| | - Peter Stange
- Universität Rostock Institut für Chemie Abteilung für Physikalische Chemie Dr.-Lorenz-Weg 2 18059 Rostock Deutschland
| | - Sabrina Gärtner
- ISIS Faculty, STFC Rutherford Appleton Laboratory Didcot OX11 0QX UK
| | | | - Dietmar Paschek
- Universität Rostock Institut für Chemie Abteilung für Physikalische Chemie Albert-Einstein-Str. 21 18059 Rostock Deutschland
| | - Gregory G. Warr
- School of Chemistry and Sydney Nano The University of Sydney NSW 2006 Australien
| | - Rob Atkin
- School of Molecular Sciences The University of Western Australia Perth Western Australia 6009 Australien
| | - Ralf Ludwig
- Universität Rostock Institut für Chemie Abteilung für Physikalische Chemie Dr.-Lorenz-Weg 2 18059 Rostock Deutschland
- Department LL&M University of Rostock Albert-Einstein-Str. 25 18059 Rostock Deutschland
- Leibniz-Institut für Katalyse an der Universität Rostock e.V. Albert-Einstein-Str. 29a 18059 Rostock Deutschland
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32
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Zeng HJ, Johnson MA, Ramdihal JD, Sumner RA, Rodriguez C, Lall-Ramnarine SI, Wishart JF. Spectroscopic Assessment of Intra- and Intermolecular Hydrogen Bonding in Ether-Functionalized Imidazolium Ionic Liquids. J Phys Chem A 2019; 123:8370-8376. [DOI: 10.1021/acs.jpca.9b04345] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Affiliation(s)
- Helen J. Zeng
- Sterling Chemistry Laboratory, Yale University, New Haven, Connecticut 06520, United States
| | - Mark A. Johnson
- Sterling Chemistry Laboratory, Yale University, New Haven, Connecticut 06520, United States
| | - Jasodra D. Ramdihal
- Chemistry Department, Queensborough Community College of the City University of New York, Bayside, New York 11364, United States
| | - Rawlric A. Sumner
- Chemistry Department, Queensborough Community College of the City University of New York, Bayside, New York 11364, United States
| | - Chanele Rodriguez
- Chemistry Department, Queensborough Community College of the City University of New York, Bayside, New York 11364, United States
| | - Sharon I. Lall-Ramnarine
- Chemistry Department, Queensborough Community College of the City University of New York, Bayside, New York 11364, United States
| | - James F. Wishart
- Chemistry Division, Brookhaven National Laboratory, Upton, New York 11973, United States
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33
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Niemann T, Neumann J, Stange P, Gärtner S, Youngs TGA, Paschek D, Warr GG, Atkin R, Ludwig R. The Double-Faced Nature of Hydrogen Bonding in Hydroxy-Functionalized Ionic Liquids Shown by Neutron Diffraction and Molecular Dynamics Simulations. Angew Chem Int Ed Engl 2019; 58:12887-12892. [PMID: 31177605 DOI: 10.1002/anie.201904712] [Citation(s) in RCA: 32] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2019] [Revised: 05/25/2019] [Indexed: 01/14/2023]
Abstract
We characterize the double-faced nature of hydrogen bonding in hydroxy-functionalized ionic liquids by means of neutron diffraction with isotopic substitution (NDIS), molecular dynamics (MD) simulations, and quantum chemical calculations. NDIS data are fit using the empirical potential structure refinement technique (EPSR) to elucidate the nearest neighbor H⋅⋅⋅O and O⋅⋅⋅O pair distribution functions for hydrogen bonds between ions of opposite charge and the same charge. Despite the presence of repulsive Coulomb forces, the cation-cation interaction is stronger than the cation-anion interaction. We compare the hydrogen-bond geometries of both "doubly charged hydrogen bonds" with those reported for molecular liquids, such as water and alcohols. In combination, the NDIS measurements and MD simulations reveal the subtle balance between the two types of hydrogen bonds: The small transition enthalpy suggests that the elusive like-charge attraction is almost competitive with conventional ion-pair formation.
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Affiliation(s)
- Thomas Niemann
- Universität Rostock, Institut für Chemie, Abteilung für Physikalische Chemie, Dr.-Lorenz-Weg 2, 18059, Rostock, Germany
| | - Jan Neumann
- Universität Rostock, Institut für Chemie, Abteilung für Physikalische Chemie, Albert-Einstein-Strasse 21, 18059, Rostock, Germany
| | - Peter Stange
- Universität Rostock, Institut für Chemie, Abteilung für Physikalische Chemie, Dr.-Lorenz-Weg 2, 18059, Rostock, Germany
| | - Sabrina Gärtner
- ISIS Faculty, STFC, Rutherford Appleton Laboratory, Didcot, OX11 0QX, UK
| | - Tristan G A Youngs
- ISIS Faculty, STFC, Rutherford Appleton Laboratory, Didcot, OX11 0QX, UK
| | - Dietmar Paschek
- Universität Rostock, Institut für Chemie, Abteilung für Physikalische Chemie, Albert-Einstein-Strasse 21, 18059, Rostock, Germany
| | - Gregory G Warr
- School of Chemistry and Sydney Nano, The University of Sydney, NSW, 2006, Australia
| | - Rob Atkin
- School of Molecular Sciences, The University of Western Australia, Perth, Western Australia, 6009, Australia
| | - 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
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34
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Ramondo F, Gontrani L, Campetella M. Coupled hydroxyl and ether functionalisation in EAN derivatives: the effect of hydrogen bond donor/acceptor groups on the structural heterogeneity studied with X-ray diffractions and fixed charge/polarizable simulations. Phys Chem Chem Phys 2019; 21:11464-11475. [PMID: 31112158 DOI: 10.1039/c9cp00571d] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
We present a study by energy-dispersive X-ray diffraction of liquid 2-(2-hydroxyethoxy)ethan-1-ammonium nitrate, NH3CH2CH2(OCH2CH2OH)+NO3- (22HHEAN). This ionic liquid is derived from the parent ethylammonium nitrate (EAN) with an ether link in the chain and a hydroxyl group in the terminal position. The absence of peaks at low-q values in the experimental diffraction curve indicates that the added polar groups and the high conformational isomerism of the cations alter strongly the nanosegregation of the parent EAN liquid. Aggregation between ionic species may involve hydrogen bonding between cations and anions and a variety of intermolecular hydrogen bonds between cations. Diffraction patterns are compared with the results of molecular dynamics simulations with two different force fields: the fixed point charge force field (GAFF) with different charge scaling protocols and the polarizable AMOEBA force field. Most point charge models lead to the appearance of a quite evident low q-peak which decreases gradually, when the percentage and type of the scaling (uniform vs. non-uniform) are increased. In the polarisable model and in the model where only anion charges are scaled to 20%, instead, the pre-peak is absent in agreement with our experiments.
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Affiliation(s)
- Fabio Ramondo
- Department of Physical and Chemical Sciences, University of L'Aquila, Via Vetoio I-67100, L'Aquila, Italy
| | - Lorenzo Gontrani
- Department of Chemistry "Giacomo Ciamician", University of Bologna, Via Selmi, 2, I-40126 Bologna, Italy. and Department of Chemistry, University "La Sapienza", Roma Piazzale Aldo Moro 5, I-00185, Roma, Italy
| | - Marco Campetella
- Department of Chemistry, University "La Sapienza", Roma Piazzale Aldo Moro 5, I-00185, Roma, Italy and Chimie ParisTech, PSL Research University, CNRS, Institut de Recherche de Chimie Paris, F-75005 Paris, France
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35
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Panja SK, Haddad B, Debdab M, Kiefer J, Chaker Y, Bresson S, Paolone A. Cluster Formation through Hydrogen Bond Bridges across Chloride Anions in a Hydroxyl-Functionalized Ionic Liquid. Chemphyschem 2019; 20:936-940. [PMID: 30821876 DOI: 10.1002/cphc.201801206] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2018] [Revised: 03/01/2019] [Indexed: 11/10/2022]
Abstract
Several recent studies of hydroxyl-functionalized ionic liquids (ILs) have shown that cation-cation interactions can be dominating these materials at the molecular level when the anion involved is weakly interacting. The hydrogen bonds between the like ions led to the formation of interesting chain-like, ring-like, or distinct dimeric (i. e. two ion pairs) supermolecular clusters. In the present work, vibrational spectroscopy (ATR-IR and Raman) and density functional theory (DFT) calculations of the hydroxyl-functionalized imidazolium ionic liquid C2 OHmimCl indicate that anion-cation hydrogen bonding interactions are dominating, leading to the formation of distinct dimeric ion pair clusters. In this arrangement, the Cl- anions function as a bridge between the cations by establishing bifurcated hydrogen bonds with the OH group of one cation and the C(2)-H of another cation. Cation-cation interactions, on the other hand, do not play a significant role in the observed clusters.
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Affiliation(s)
- Sumit Kumar Panja
- Department of Inorganic and Physical Chemistry, Indian Institute of Science, Bangalore, 560012, Karnataka, India
| | - Boumediene Haddad
- Department of Chemistry, Dr Moulay Tahar University of Saida, Algeria
| | - Mansour Debdab
- Laboratoire de Synthèse et Catalyse Tiaret LSCT, University of Tiaret, Algeria
| | - Johannes Kiefer
- Technische Thermodynamik, Universität Bremen, Badgasteiner Str. 1, 28359, Bremen, Germany
| | - Yassine Chaker
- Laboratoire de Synthèse et Catalyse Tiaret LSCT, University of Tiaret, Algeria
| | - Serge Bresson
- Laboratoire de Physique des Systèmes Complexes, Université Picardie Jules Verne, 33 rue St Leu, 80039, Amiens cedex, France
| | - Annalisa Paolone
- Consiglio Nazionale delle Ricerche Instituto dei Sistemi Complessi (CNR-ISC), University of Rome La Sapienza, Piazzale A. Moro 5, 00185, Roma, Italy
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36
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Zaitsau DH, Neumann J, Niemann T, Strate A, Paschek D, Verevkin SP, Ludwig R. Isolating the role of hydrogen bonding in hydroxyl-functionalized ionic liquids by means of vaporization enthalpies, infrared spectroscopy and molecular dynamics simulations. Phys Chem Chem Phys 2019; 21:20308-20314. [DOI: 10.1039/c9cp04337c] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Abstract
Hydrogen bonding in hydroxyl-functionalized ionic liquids (right) prevents favourable dispersion interaction between cation and anion (left). We analyze this subtle balance of interactions by combining calorimetry, IR spectroscopy and MD simulations.
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Affiliation(s)
- Dzmitry H. Zaitsau
- Universität Rostock
- Institut für Chemie
- Abteilung für Physikalische Chemie
- Rostock
- Germany
| | - Jan Neumann
- Universität Rostock
- Institut für Chemie
- Abteilung für Physikalische Chemie
- Rostock
- Germany
| | - Thomas Niemann
- Universität Rostock
- Institut für Chemie
- Abteilung für Physikalische Chemie
- Rostock
- Germany
| | - Anne Strate
- Universität Rostock
- Institut für Chemie
- Abteilung für Physikalische Chemie
- Rostock
- Germany
| | - Dietmar Paschek
- Universität Rostock
- Institut für Chemie
- Abteilung für Physikalische Chemie
- Rostock
- Germany
| | - Sergey P. Verevkin
- Universität Rostock
- Institut für Chemie
- Abteilung für Physikalische Chemie
- Rostock
- Germany
| | - Ralf Ludwig
- Universität Rostock
- Institut für Chemie
- Abteilung für Physikalische Chemie
- Rostock
- Germany
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37
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Niemann T, Stange P, Strate A, Ludwig R. When hydrogen bonding overcomes Coulomb repulsion: from kinetic to thermodynamic stability of cationic dimers. Phys Chem Chem Phys 2019; 21:8215-8220. [PMID: 30672530 DOI: 10.1039/c8cp06417b] [Citation(s) in RCA: 26] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Quantum chemical calculations have been employed to study the kinetic and thermodynamic stability of hydroxy-functionalized 1-(3-hydroxyalkyl)pyridinium cationic dimers. For [Py-(CH2)n-OH+]2 structures with n = 2-17 we have calculated the robust local minima with clear dissociation barriers preventing their "Coulomb explosion" into separated cations. For n = 15 hydrogen bonding and dispersion forces fully compensate for the repulsive Coulomb forces between the cations allowing for the quantification of the pure hydrogen bond in the order of 20 kJ mol-1. The increasing kinetic stability even turns to thermodynamic stability with further elongated hydroxyalkyl chains. Now, quantum-type short-range attraction wins over classical long-range electrostatic repulsion resulting in negative binding energies and providing the first thermodynamically stable cationic dimers. The electronic, structural and spectroscopic signatures of the cationic dimers could be correlated to NBO parameters, supporting the existence of anti-electrostatic hydrogen bonds (AEHB) as recently suggested by Weinhold. In principle, these pure cationic dimers should be detectable in gas-phase experiments at low temperatures without the need of mediating molecules or counteranions.
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Affiliation(s)
- T Niemann
- Universität Rostock, Institut für Chemie, Abteilung für Physikalische Chemie, Dr.-Lorenz-Weg 2, 18059, Rostock, Germany.
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38
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Niemann T, Strate A, Ludwig R, Zeng HJ, Menges FS, Johnson MA. Cooperatively enhanced hydrogen bonds in ionic liquids: closing the loop with molecular mimics of hydroxy-functionalized cations. Phys Chem Chem Phys 2019; 21:18092-18098. [DOI: 10.1039/c9cp03300a] [Citation(s) in RCA: 25] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
The combined experimental and theoretical approach for the gas and the liquid phases provides a quantitative understanding of the competition between differently H-bonded and charged constituents in liquids.
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Affiliation(s)
- Thomas Niemann
- Department of Chemistry
- University of Rostock
- 18059 Rostock
- Germany
- Department Life
| | - Anne Strate
- Department of Chemistry
- University of Rostock
- 18059 Rostock
- Germany
- Department Life
| | - Ralf Ludwig
- Department of Chemistry
- University of Rostock
- 18059 Rostock
- Germany
- Department Life
| | - Helen J. Zeng
- Sterling Chemistry Laboratory
- Yale University
- New Haven
- USA
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Tan X, Liu X, Yao X, Zhang Y, Jiang K. Theoretical Study of Ionic Liquid Clusters Catalytic Effect on the Fixation of CO2. Ind Eng Chem Res 2018. [DOI: 10.1021/acs.iecr.8b03947] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Xin Tan
- CAS Key Laboratory of Green Process and Engineering, State Key Laboratory of Multiphase Complex Systems, Beijing Key Laboratory of Ionic Liquids Clean Process, Institute of Process Engineering, Chinese Academy of Sciences, 1 North second Street, Zhongguancun, Haidian District, Beijing 100190, China
- School of Chemistry and Chemical Engineering, University of Chinese Academy of Sciences, 19A Yuquan Road, Shijingshan District, Beijing 100049, China
| | - Xiaomin Liu
- CAS Key Laboratory of Green Process and Engineering, State Key Laboratory of Multiphase Complex Systems, Beijing Key Laboratory of Ionic Liquids Clean Process, Institute of Process Engineering, Chinese Academy of Sciences, 1 North second Street, Zhongguancun, Haidian District, Beijing 100190, China
- School of Chemistry and Chemical Engineering, Qingdao University, Qingdao 266071, Shandong, China
| | - Xiaoqian Yao
- CAS Key Laboratory of Green Process and Engineering, State Key Laboratory of Multiphase Complex Systems, Beijing Key Laboratory of Ionic Liquids Clean Process, Institute of Process Engineering, Chinese Academy of Sciences, 1 North second Street, Zhongguancun, Haidian District, Beijing 100190, China
| | - Yaqin Zhang
- CAS Key Laboratory of Green Process and Engineering, State Key Laboratory of Multiphase Complex Systems, Beijing Key Laboratory of Ionic Liquids Clean Process, Institute of Process Engineering, Chinese Academy of Sciences, 1 North second Street, Zhongguancun, Haidian District, Beijing 100190, China
| | - Kun Jiang
- CAS Key Laboratory of Green Process and Engineering, State Key Laboratory of Multiphase Complex Systems, Beijing Key Laboratory of Ionic Liquids Clean Process, Institute of Process Engineering, Chinese Academy of Sciences, 1 North second Street, Zhongguancun, Haidian District, Beijing 100190, China
- School of Chemistry and Chemical Engineering, University of Chinese Academy of Sciences, 19A Yuquan Road, Shijingshan District, Beijing 100049, China
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Nie B, Li R, Wu Y, Yuan X, Zhang W. Theoretical Calculation of the Thermodynamic Properties of 20 Amino Acid Ionic Liquids. J Phys Chem B 2018; 122:10548-10557. [PMID: 30359517 DOI: 10.1021/acs.jpcb.8b06813] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The thermodynamic properties of gas-phase amino acid ionic liquids (AAILs) containing 20 amino acids ([AA]-) and 1-ethyl-3-methylimidazolium ([Emim]+) are studied using a combination of the ab initio method, molecular dynamics simulations, Born-Haber (BH) cycle analysis, and isodesmic reactions. The M06-2X/TZVP method is used to explore the structure and dissociation enthalpies of [Emim][AA] by considering dispersion interaction, and the MP2/Aug-cc-pVTZ method is used to correct these enthalpies. The vaporization enthalpies of all 20 AAILs are calculated by molecular dynamics simulations, and the gas-phase formation enthalpies (Δf H) of the 20 [AA]- anions and [Emim]+ cation are calculated by the density functional theory/M06-2X method and isodesmic reaction approaches. To obtain the Δf H of the AAILs, interconnections in the corresponding BH cycles are evaluated. A systematic study of the 20 [Emim][AA] ion pairs provides some initial factors contributing to the thermodynamic properties of AAILs: including length of the alkyl chain, interatomic electronic effects, steric repulsion from the cyclic group, and H-bonds formed by functional groups. Generally speaking, the results of this work provide insights into the structure-property relationships of not only ILs but also any ionic or molecular substance.
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Niemann T, Strate A, Ludwig R, Zeng HJ, Menges FS, Johnson MA. Spektroskopischer Nachweis einer attraktiven Kation‐Kation‐ Wechselwirkung in OH‐funktionalisierten ionischen Flüssigkeiten: ein H‐Brücken‐gebundenes kettenförmiges Trimer. Angew Chem Int Ed Engl 2018. [DOI: 10.1002/ange.201808381] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Affiliation(s)
- Thomas Niemann
- Institut für Chemie Universität Rostock 18059 Rostock Deutschland
- Institut für Leben, Licht & Materie Universität Rostock 18051 Rostock Deutschland
| | - Anne Strate
- Institut für Chemie Universität Rostock 18059 Rostock Deutschland
- Institut für Leben, Licht & Materie Universität Rostock 18051 Rostock Deutschland
| | - Ralf Ludwig
- Institut für Chemie Universität Rostock 18059 Rostock Deutschland
- Institut für Leben, Licht & Materie Universität Rostock 18051 Rostock Deutschland
- Leibniz-Institut für Katalyse e.V. Albert-Einstein-Straße 29a 18059 Rostock Deutschland
| | - Helen J. Zeng
- Sterling Chemistry Laboratory Universität Yale New Haven CT 06520 USA
| | - Fabian S. Menges
- Sterling Chemistry Laboratory Universität Yale New Haven CT 06520 USA
| | - Mark A. Johnson
- Sterling Chemistry Laboratory Universität Yale New Haven CT 06520 USA
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Niemann T, Strate A, Ludwig R, Zeng HJ, Menges FS, Johnson MA. Spectroscopic Evidence for an Attractive Cation-Cation Interaction in Hydroxy-Functionalized Ionic Liquids: A Hydrogen-Bonded Chain-like Trimer. Angew Chem Int Ed Engl 2018; 57:15364-15368. [PMID: 30303295 DOI: 10.1002/anie.201808381] [Citation(s) in RCA: 43] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2018] [Indexed: 12/29/2022]
Abstract
We address the formation of hydrogen bonded domains among the cationic constituents of the ionic liquid (IL) 1-(3-hydroxypropyl)pyridinium tetrafluoroborate [HPPy][BF4 ] by means of cryogenic ion vibrational predissociation spectroscopy of cold (ca. 35 K) gas-phase cluster ions and quantum chemistry. Specifically, analysis of the OH stretching bands reveals a chain-like OH⋅⋅⋅OH⋅⋅⋅OH⋅⋅⋅BF4 - binding motif involving the three cations in the cationic quinary cluster ion (HPPy+ )3 (BF4 - )2 . Calculations show that this cooperative H-bond attraction compensates for the repulsive Coulomb forces and results in stable complexes that successfully compete with those in which the OH groups are predominantly attached to the counter anions. Our combined experimental and theoretical approach provides insight into the cooperative effects that lead to the formation of hydrogen bonded domains involving the cationic constituents of ILs.
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Affiliation(s)
- Thomas Niemann
- Department of Chemistry, University of Rostock, 18059, Rostock, Germany.,Department Life, Light & Matter, University of Rostock, 18051, Rostock, Germany
| | - Anne Strate
- Department of Chemistry, University of Rostock, 18059, Rostock, Germany.,Department Life, Light & Matter, University of Rostock, 18051, Rostock, Germany
| | - Ralf Ludwig
- Department of Chemistry, University of Rostock, 18059, Rostock, Germany.,Department Life, Light & Matter, University of Rostock, 18051, Rostock, Germany.,Leibniz-Institut für Katalyse e.V., Albert-Einstein-Str. 29a, 18059, Rostock, Germany
| | - Helen J Zeng
- Sterling Chemistry Laboratory, Yale University, New Haven, CT, 06520, USA
| | - Fabian S Menges
- Sterling Chemistry Laboratory, Yale University, New Haven, CT, 06520, USA
| | - Mark A Johnson
- Sterling Chemistry Laboratory, Yale University, New Haven, CT, 06520, USA
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Panja SK, Haddad B, Kiefer J. Clusters of the Ionic Liquid 1-Hydroxyethyl-3-methylimidazolium Picrate: From Theoretical Prediction in the Gas Phase to Experimental Evidence in the Solid State. Chemphyschem 2018; 19:3061-3068. [DOI: 10.1002/cphc.201800684] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2018] [Indexed: 01/08/2023]
Affiliation(s)
- Sumit K. Panja
- Department of Inorganic and Physical Chemistry; Indian Institute of Science; Bangalore 560012 Karnataka India
| | - Boumediene Haddad
- Department of Chemistry; Dr Moulay Tahar University; Saïda EN-NASR, BP:138 Algeria
| | - Johannes Kiefer
- Technische Thermodynamik; Universität Bremen; Badgasteiner Str. 1 28359 Bremen Germany
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Niemann T, Zaitsau D, Strate A, Villinger A, Ludwig R. Cationic clustering influences the phase behaviour of ionic liquids. Sci Rep 2018; 8:14753. [PMID: 30283059 PMCID: PMC6170405 DOI: 10.1038/s41598-018-33176-6] [Citation(s) in RCA: 45] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2018] [Accepted: 09/19/2018] [Indexed: 11/17/2022] Open
Abstract
“Unlike charges attract, but like charges repel”. This conventional wisdom has been recently challenged for ionic liquids. It could be shown that like-charged ions attract each other despite the powerful opposing electrostatic forces. In principle, cooperative hydrogen bonding between ions of like-charge can overcome the repulsive Coulomb interaction while pushing the limits of chemical bonding. The key challenge of this solvation phenomenon is to establish design principles for the efficient formation of clusters of like-charged ions in ionic liquids. This is realised here for a set of well-suited ionic liquids including the same hydrophobic anion but different cations all equipped with hydroxyethyl groups for possible H-bonding. The formation of H-bonded cationic clusters can be controlled by the delocalization of the positive charge on the cations. Strongly localized charge results in cation-anion interaction, delocalized charge leads to the formation of cationic clusters. For the first time we can show, that the cationic clusters influence the properties of ILs. ILs comprising these clusters can be supercooled and form glasses. Crystalline structures are obtained only, if the ILs are dominantly characterized by the attraction between opposite-charged ions resulting in conventional ion pairs. That may open a new path for controlling glass formation and crystallization. The glass temperatures and the phase transitions of the ILs are observed by differential scanning calorimetry (DSC) and infrared (IR) spectroscopy.
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Affiliation(s)
- Thomas Niemann
- Universität Rostock, Institut für Chemie, Abteilung für Physikalische Chemie, Dr. -Lorenz-Weg 2, 18059, Rostock, Germany
| | - Dimitri Zaitsau
- Universität Rostock, Institut für Chemie, Abteilung für Physikalische Chemie, Dr. -Lorenz-Weg 2, 18059, Rostock, Germany
| | - Anne Strate
- Universität Rostock, Institut für Chemie, Abteilung für Physikalische Chemie, Dr. -Lorenz-Weg 2, 18059, Rostock, Germany
| | - Alexander Villinger
- Universität Rostock, Institut für Chemie, Abteilung für Anorganische Chemie, Albert-Einstein-Str. 3a, 18059, Rostock, Germany
| | - Ralf Ludwig
- Universität Rostock, Institut für Chemie, Abteilung für Physikalische Chemie, Dr. -Lorenz-Weg 2, 18059, Rostock, Germany. .,Department Life, Light & Matter, University of Rostock, 18051, Rostock, Germany. .,Leibniz-Institut für Katalyse an der Universität Rostock e.V., Albert-Einstein-Str. 29a, 18059, Rostock, Germany.
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Le Donne A, Adenusi H, Porcelli F, Bodo E. Hydrogen Bonding as a Clustering Agent in Protic Ionic Liquids: Like-Charge vs Opposite-Charge Dimer Formation. ACS OMEGA 2018; 3:10589-10600. [PMID: 31459182 PMCID: PMC6645488 DOI: 10.1021/acsomega.8b01615] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 07/11/2018] [Accepted: 08/22/2018] [Indexed: 06/10/2023]
Abstract
The local structure of a series of homologous protic ionic liquids (PILs) is investigated using ab initio computations and ab initio-based molecular dynamics. The purpose of this work is to show that in PILs the network of hydrogen bonds may promote like-charge clustering between anionic species. We correlate the theoretical evidence of this possibility with viscosity experimental data. The homologous series of liquids is obtained by coupling choline with amino acid anions and varying the side chain. We find that the frictional properties of the liquids are clearly connected to the ability of the side chain to establish additional hydrogen bonds (other than the trivial cation-anion interaction). We also show that the large variation of bulk properties along the series of compounds can be explained by assuming that one of the sources of friction in the bulk liquid is the like-charge interaction between anions.
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