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Sanchez Merlinsky L, Hemmeter D, Baraldo LM, Maier F, Steinrück HP, Williams FJ. Unlocking the Fluorine-Free Buoy Effect: Surface-Enriched Ruthenium Polypyridine Complexes in Ionic Liquids. ChemistryOpen 2024:e202400092. [PMID: 38687137 DOI: 10.1002/open.202400092] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2024] [Indexed: 05/02/2024] Open
Abstract
Controlling the local concentration of metal complexes at the surface of ionic liquids (ILs) is a highly sought-after objective due to its pivotal implications in supported ionic liquid phase (SILP) catalysis. Equally important is to avoid per- and polyfluorinated substances due to environmental concerns. Herein, we investigate the surface enrichment of Ru polypyridyl complexes with fluorine-free alkylic side groups of varying lengths and shapes, using the hydrophilic IL [C2C1Im][OAc] as solvent. Additional charged carboxylate groups are included into the polypyridyl ligands to increase the solubility of the complex in the IL. When the ligand system is functionalized with long and hydrophobic alkyl side chains, the complex predominantly localizes at the IL/vacuum interface, as deduced from angle-resolved X-ray photoelectron spectroscopy. Conversely, in the presence of short or more bulky substituents, no surface enrichment is observed. This buoy-like behaviour with fluorine-free side groups is explored for 0.05 %mol to 1 %mol solutions. Intriguingly, surface saturation occurs at approximately 0.5 %mol, which is beneficial to the efficient operation of catalytic systems featuring high surface areas, such as SILP catalysts.
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Affiliation(s)
- Luciano Sanchez Merlinsky
- Departamento de Química Inorgánica, Analítica y Química Física, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Buenos Aires, Argentina
- Instituto de Química Física de los Materiales, Medio Ambiente y Energía, CONICET-Universidad de Buenos Aires, Buenos Aires, Argentina
| | - Daniel Hemmeter
- Lehrstuhl für Physikalische Chemie II, Friedrich-Alexander-Universität Erlangen-Nürnberg, Egerlandstraße 3, Erlangen, Germany
| | - Luis M Baraldo
- Departamento de Química Inorgánica, Analítica y Química Física, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Buenos Aires, Argentina
- Instituto de Química Física de los Materiales, Medio Ambiente y Energía, CONICET-Universidad de Buenos Aires, Buenos Aires, Argentina
| | - Florian Maier
- Lehrstuhl für Physikalische Chemie II, Friedrich-Alexander-Universität Erlangen-Nürnberg, Egerlandstraße 3, Erlangen, Germany
| | - Hans-Peter Steinrück
- Lehrstuhl für Physikalische Chemie II, Friedrich-Alexander-Universität Erlangen-Nürnberg, Egerlandstraße 3, Erlangen, Germany
| | - Federico J Williams
- Departamento de Química Inorgánica, Analítica y Química Física, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Buenos Aires, Argentina
- Instituto de Química Física de los Materiales, Medio Ambiente y Energía, CONICET-Universidad de Buenos Aires, Buenos Aires, Argentina
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2
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Walz MM, Signorelli MRM, Caleman C, Costa LT, Björneholm O. The Surface of Ionic Liquids in Water: From an Ionic Tug of War to a Quasi-Ordered Two-Dimensional Layer. Chemphyschem 2024; 25:e202300551. [PMID: 37991256 DOI: 10.1002/cphc.202300551] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2023] [Revised: 10/19/2023] [Indexed: 11/23/2023]
Abstract
The sustainable development encompasses the search for new materials for energy storage, gas capture, separation, and solvents in industrial processes that can substitute conventional ones in an efficient and clean manner. Ionic liquids (ILs) emerged and have been advanced as alternative materials for such applications, but an obstacle is their hygroscopicity and the effects on their physical properties in the presence of humidity. Several industrial processes depend on the aqueous interfacial properties, and the main focus of this work is the water/IL interface. The behavior of the aqueous ionic liquids at the water-vacuum interface is representative for their water interfacial properties. Using X-ray photoelectron spectroscopy in combination with molecular dynamics simulations we investigate four aqueous IL systems, and provide molecular level insight on the interfacial behaviour of the ionic liquids, such as ion-pair formation, orientation and surface concentration. We find that ionic liquids containing a chloride anion have a lowered surface enrichment due to the low surface propensity of chloride. In contrast, the ionic liquids containing a bistriflimide anion are extremely surface-enriched due to cooperative surface propensity between the cations and anions, forming a two-dimensional ionic liquid on the water surface at low concentrations.
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Affiliation(s)
- Marie-Madeleine Walz
- Uppsala University, Department of Cell and Molecular Biology, Computational Biology and Bioinformatics, Uppsala, Sweden
- Current address: Novavax AB, Kungsgatan 109, 753 18, Uppsala, Sweden
| | | | - Carl Caleman
- Uppsala University, Department of Physics and Astronomy, X-ray Photon Science, Uppsala, Sweden
- Deutches Elektronen-Synchrotron DESY, Center for Free-electron Laser Science, Hamburg, Germany
| | - Luciano T Costa
- Fluminense Federal University-Outeiro de São João Batista, Institute of Chemistry, MolMod-CS, Niteroi, RJ, Brazil
| | - Olle Björneholm
- Uppsala University, Department of Physics and Astronomy, X-ray Photon Science, Uppsala, Sweden
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3
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Bomhardt K, Schneider P, Glaser T, Dürr M. Surface Properties of Ionic Liquids: A Mass Spectrometric View Based on Soft Cluster-Induced Desorption. JOURNAL OF THE AMERICAN SOCIETY FOR MASS SPECTROMETRY 2022; 33:974-980. [PMID: 35579531 DOI: 10.1021/jasms.2c00038] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
Desorption/ionization induced by neutral clusters (DINeC) in combination with mass spectrometry (MS) was used for the investigation of the molecular composition of the surface of ionic liquids (IL). Based on the surface sensitivity of DINeC-MS, accumulation of either cations or anions was discriminated on the surface of bulk IL depending on the molecular structure of the IL components. In particular, cations with long alkyl chains aggregate on the surface, but this tendency is more reduced the larger the respective anion is; in the case of larger anions and smaller cations, it can be even reversed. For thin layers of IL, the ratio between cations and anions as detected in the mass spectra was found to be further influenced by the substrate surface.
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Affiliation(s)
- Karolin Bomhardt
- Institut für Angewandte Physik and Zentrum für Materialforschung, Justus-Liebig-Universität Giessen, Heinrich-Buff-Ring 16, D-35392 Giessen, Germany
| | - Pascal Schneider
- Institut für Angewandte Physik and Zentrum für Materialforschung, Justus-Liebig-Universität Giessen, Heinrich-Buff-Ring 16, D-35392 Giessen, Germany
| | - Timo Glaser
- Institut für Angewandte Physik and Zentrum für Materialforschung, Justus-Liebig-Universität Giessen, Heinrich-Buff-Ring 16, D-35392 Giessen, Germany
| | - Michael Dürr
- Institut für Angewandte Physik and Zentrum für Materialforschung, Justus-Liebig-Universität Giessen, Heinrich-Buff-Ring 16, D-35392 Giessen, Germany
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4
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Massicot S, Sasaki T, Lexow M, Maier F, Kuwabata S, Steinrück H. On‐Surface Metathesis of an Ionic Liquid on Ag(111). Chemistry 2022; 28:e202200167. [PMID: 35363397 PMCID: PMC9321566 DOI: 10.1002/chem.202200167] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2022] [Indexed: 11/17/2022]
Abstract
We investigated the adsorption, surface enrichment, ion exchange, and on‐surface metathesis of ultrathin mixed IL films on Ag(111). We stepwise deposited 0.5 ML of the protic IL diethylmethylammonium trifluoromethanesulfonate ([dema][TfO]) and 1.0 ML of the aprotic IL 1‐methyl‐3‐octylimidazolium hexafluorophosphate ([C8C1Im][PF6]) at around 90 K. Thereafter, the resulting layered frozen film was heated to 550 K, and the thermally induced phenomena were monitored in situ by angle‐resolved X‐ray photoelectron spectroscopy. Between 135 and 200 K, [TfO]− anions at the Ag(111) surface are exchanged by [PF6]− anions and enriched together with [C8C1Im]+ cations at the IL/vacuum interface. Upon further heating, [dema][PF6] and [OMIm][PF6] desorb selectively at ∼235 and ∼380 K, respectively. Hereby, a wetting layer of pure [C8C1Im][TfO] is formed by on‐surface metathesis at the IL/metal interface, which completely desorbs at ∼480 K. For comparison, ion enrichment at the vacuum/IL interface was also studied in macroscopic IL mixtures, where no influence of the solid support is expected.
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Affiliation(s)
- Stephen Massicot
- Lehrstuhl für Physikalische Chemie II Friedrich-Alexander-Universität Erlangen-Nürnberg Egerlandstr. 3 91058 Erlangen Germany
| | - Tomoya Sasaki
- Department of Applied Chemistry Graduate School of Engineering Osaka University Yamada-oka 2–1, Suita Osaka 565-0871 Japan
| | - Matthias Lexow
- Lehrstuhl für Physikalische Chemie II Friedrich-Alexander-Universität Erlangen-Nürnberg Egerlandstr. 3 91058 Erlangen Germany
| | - Florian Maier
- Lehrstuhl für Physikalische Chemie II Friedrich-Alexander-Universität Erlangen-Nürnberg Egerlandstr. 3 91058 Erlangen Germany
| | - Susumu Kuwabata
- Department of Applied Chemistry Graduate School of Engineering Osaka University Yamada-oka 2–1, Suita Osaka 565-0871 Japan
| | - Hans‐Peter Steinrück
- Lehrstuhl für Physikalische Chemie II Friedrich-Alexander-Universität Erlangen-Nürnberg Egerlandstr. 3 91058 Erlangen Germany
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5
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Purcell SM, Lane PD, D'Andrea L, Elstone NS, Bruce DW, Slattery JM, Smoll EJ, Greaves SJ, Costen ML, Minton TK, McKendrick KG. Surface Structure of Alkyl/Fluoroalkylimidazolium Ionic-Liquid Mixtures. J Phys Chem B 2022; 126:1962-1979. [PMID: 35225614 PMCID: PMC9007465 DOI: 10.1021/acs.jpcb.1c10460] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
The gas-liquid interface of ionic liquids (ILs) is critically important in many applications, for example, in supported IL phase (SILP) catalysis. Methods to investigate the interfacial structure in these systems will allow their performance to be improved in a rational way. In this study, reactive-atom scattering (RAS), surface tension measurements, and molecular dynamics (MD) simulations were used to study the vacuum interface of mixtures of partially fluorinated and normal alkyl ILs. The underlying aim was to understand whether fluorinated IL ions could be used as additives to modify the surface structure of one of the most widely used families of alkyl ILs. The series of ILs 1-alkyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ([Cnmim][Tf2N]) with n = 4-12 were mixed with a fixed-length, semiperfluorinated analogue (1H,1H,2H,2H-perfluorooctyl)-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ([C8mimF13][Tf2N]), forming [Cnmim](1-x)[C8mimF13]x[Tf2N] mixtures, where x is the bulk mole fraction of the fluorinated component. The RAS-LIF method combined O-atom projectiles with laser-induced fluorescence (LIF) detection of the product OH as a measure of surface exposure of the alkyl chains. For [C8mim](1-x)[C8mimF13]x[Tf2N] mixtures, RAS-LIF OH yields are below those expected from stoichiometry. There are quantitatively consistent negative deviations from linearity of the surface tension. Both results imply that the lower-surface-tension fluoroalkyl material dominates the surface. A similar deficit is found for alkyl chain lengths n = 4, 6, 8, and 12 and for all (nonzero) x investigated by RAS-LIF. Accessible-surface-area (ASA) analyses of the MD simulations for [Cnmim](1-x)[C8mimF13]x[Tf2N] mixtures qualitatively reproduce the same primary effect of fluoro-chain predominance of the surface over most of the range of n. However, there are significant quantitative discrepancies between MD ASA predictions and experiment relating to the strength of any n-dependence of the relative alkyl coverage at fixed x, and on the x-dependence at fixed n. These discrepancies are discussed in the context of detailed examinations of the surface structures predicted in the MD simulations. Potential explanations, beyond experimental artifacts, include inadequacies in the classical force fields used in the MD simulations or the inability of simple ASA algorithms to capture dynamical factors that influence RAS-LIF yields.
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Affiliation(s)
- Simon M Purcell
- Institute of Chemical Sciences, School of Engineering and Physical Sciences, Heriot-Watt University, Edinburgh EH14 4AS, U.K
| | - Paul D Lane
- Institute of Chemical Sciences, School of Engineering and Physical Sciences, Heriot-Watt University, Edinburgh EH14 4AS, U.K
| | - Lucía D'Andrea
- Department of Chemistry, University of York, Heslington, York YO10 5DD, U.K
| | - Naomi S Elstone
- Department of Chemistry, University of York, Heslington, York YO10 5DD, U.K
| | - Duncan W Bruce
- Department of Chemistry, University of York, Heslington, York YO10 5DD, U.K
| | - John M Slattery
- Department of Chemistry, University of York, Heslington, York YO10 5DD, U.K
| | - Eric J Smoll
- Department of Chemistry and Biochemistry, Montana State University, Bozeman, Montana 59717, United States
| | - Stuart J Greaves
- Institute of Chemical Sciences, School of Engineering and Physical Sciences, Heriot-Watt University, Edinburgh EH14 4AS, U.K
| | - Matthew L Costen
- Institute of Chemical Sciences, School of Engineering and Physical Sciences, Heriot-Watt University, Edinburgh EH14 4AS, U.K
| | - Timothy K Minton
- Ann and H.J. Smead Department of Aerospace Engineering Sciences, University of Colorado Boulder, Boulder, Colorado 80303, United States
| | - Kenneth G McKendrick
- Institute of Chemical Sciences, School of Engineering and Physical Sciences, Heriot-Watt University, Edinburgh EH14 4AS, U.K
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6
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Massicot S, Sasaki T, Lexow M, Shin S, Maier F, Kuwabata S, Steinrück HP. Adsorption, Wetting, Growth, and Thermal Stability of the Protic Ionic Liquid Diethylmethylammonium Trifluoromethanesulfonate on Ag(111) and Au(111). LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2021; 37:11552-11560. [PMID: 34569794 PMCID: PMC8495895 DOI: 10.1021/acs.langmuir.1c01823] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/08/2021] [Indexed: 06/13/2023]
Abstract
We have studied the adsorption, wetting, growth, and thermal evolution of the protic IL diethylmethylammonium trifluoromethanesulfonate ([dema][TfO]) on Au(111) and Ag(111). Ultrathin films were deposited at room temperature (RT) and at 90 K, and were characterized in situ by angle-resolved X-ray photoelectron spectroscopy. For both surfaces, we observe that independent of temperature, initially, a closed 2D wetting layer forms. While the film thickness does not increase past this wetting layer at RT, at 200 K and below, "moderate" 3D island growth occurs on top of the wetting layer. Upon heating, on Au(111), the [dema][TfO] multilayers desorb at 292 K, leaving an intact [dema][TfO] wetting layer, which desorbs intact at 348 K. The behavior on Ag(111) is much more complex. Upon heating [dema][TfO] deposited at 90 K, the [dema]+ cations deprotonate in two steps at 185 and 305 K, yielding H[TfO] and volatile [dema]0. At 355 K, the formed H[TfO] wetting layer partly desorbs (∼50%) and partly decomposes to form an F-containing surface species, which is stable up to 570 K.
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Affiliation(s)
- Stephen Massicot
- Lehrstuhl
für Physikalische Chemie 2, Friedrich-Alexander-Universität
Erlangen-Nürnberg, Egerlandstr. 3, 91058 Erlangen, Germany
| | - Tomoya Sasaki
- Department
of Applied Chemistry, Graduate School of Engineering, Osaka University, Yamada-oka 2-1, Suita, Osaka 565-0871, Japan
| | - Matthias Lexow
- Lehrstuhl
für Physikalische Chemie 2, Friedrich-Alexander-Universität
Erlangen-Nürnberg, Egerlandstr. 3, 91058 Erlangen, Germany
| | - Sunghwan Shin
- Lehrstuhl
für Physikalische Chemie 2, Friedrich-Alexander-Universität
Erlangen-Nürnberg, Egerlandstr. 3, 91058 Erlangen, Germany
| | - Florian Maier
- Lehrstuhl
für Physikalische Chemie 2, Friedrich-Alexander-Universität
Erlangen-Nürnberg, Egerlandstr. 3, 91058 Erlangen, Germany
| | - Susumu Kuwabata
- Department
of Applied Chemistry, Graduate School of Engineering, Osaka University, Yamada-oka 2-1, Suita, Osaka 565-0871, Japan
| | - Hans-Peter Steinrück
- Lehrstuhl
für Physikalische Chemie 2, Friedrich-Alexander-Universität
Erlangen-Nürnberg, Egerlandstr. 3, 91058 Erlangen, Germany
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7
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Meusel M, Lexow M, Gezmis A, Bayer A, Maier F, Steinrück HP. Growth of Multilayers of Ionic Liquids on Au(111) Investigated by Atomic Force Microscopy in Ultrahigh Vacuum. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2020; 36:13670-13681. [PMID: 33156635 PMCID: PMC7676296 DOI: 10.1021/acs.langmuir.0c02596] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 09/01/2020] [Revised: 10/20/2020] [Indexed: 06/11/2023]
Abstract
Understanding the growth of ultrathin films of ionic liquids (ILs) on metal surfaces is of highest relevance for a variety of applications. We present a detailed study of the growth of the wetting layer and successive multilayers of 1,3-dimethylimidazolium bis[(trifluoromethyl)sulfonyl]imide ([C1C1Im][Tf2N]) on Au(111). By atomic force microscopy (AFM) in ultrahigh vacuum, we follow the temperature-dependent behavior between 110 and 300 K at defined coverages. We initially observe the formation of a wetting layer with a thickness of ∼0.37 nm with anions and cations arranged in a checkerboard structure. Stable AFM imaging up to 280 K allows us to follow the IL growing on top of the wetting layer in bilayers with an average thickness of ∼0.71 nm, that is, double the height of the wetting layer, in a bilayer-by-bilayer fashion. This growth behavior is independently confirmed from the surface morphology, as deduced from AFM and angle-resolved X-ray photoelectron spectroscopy. High-resolution AFM images at 110 K allow for identifying the molecular surface structure of the bilayers as a striped phase, which is one of the phases also seen for the wetting layer (Meusel, M.; Lexow, M.; Gezmis, A.; Schotz, S.; Wagner, M.; Bayer, A.; Maier, F.; Steinrück, H. P. Atomic Force and Scanning Tunneling Microscopy of Ordered Ionic Liquid Wetting Layers from 110 K up to Room Temperature. ACS Nano 2020, 14, 9000-9010).
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Affiliation(s)
- Manuel Meusel
- Lehrstuhl für Physikalische
Chemie II, Universität Erlangen-Nürnberg, Egerlandstrasse 3, 91058 Erlangen, Germany
| | - Matthias Lexow
- Lehrstuhl für Physikalische
Chemie II, Universität Erlangen-Nürnberg, Egerlandstrasse 3, 91058 Erlangen, Germany
| | - Afra Gezmis
- Lehrstuhl für Physikalische
Chemie II, Universität Erlangen-Nürnberg, Egerlandstrasse 3, 91058 Erlangen, Germany
| | - Andreas Bayer
- Lehrstuhl für Physikalische
Chemie II, Universität Erlangen-Nürnberg, Egerlandstrasse 3, 91058 Erlangen, Germany
| | - Florian Maier
- Lehrstuhl für Physikalische
Chemie II, Universität Erlangen-Nürnberg, Egerlandstrasse 3, 91058 Erlangen, Germany
| | - Hans-Peter Steinrück
- Lehrstuhl für Physikalische
Chemie II, Universität Erlangen-Nürnberg, Egerlandstrasse 3, 91058 Erlangen, Germany
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8
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Oz E, Sahin O, Okur HI, Suzer S. Surface Propensity of Anions in a Binary Ionic-Liquid Mixture Assessed by Full-Range Angle-Resolved X-ray Photoelectron Spectroscopy and Surface-Tension Measurements. Chemphyschem 2020; 21:2397-2401. [PMID: 32955763 DOI: 10.1002/cphc.202000750] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2020] [Revised: 09/18/2020] [Indexed: 11/09/2022]
Abstract
Angle-resolved X-ray photoelectron spectroscopy and contact-angle measurements guided by a signal attenuation model are utilized to extract molar composition and anion enrichment in the vacuum interface of a binary ionic liquid mixture, having a common quaternary ammonium cation and two different anions. By using the intensity ratio of the F1s peaks belonging to the two different anions recorded at the full electron take-off angle range, from 0° to 80°, we have determined that only a fractionally covered and anion enriched surface layer can predict the AR-XPS data, which is also consistent with surface tension measurements. Moreover, the more bulky and non-spherical anion enrichment is evident even at the conventional and the so assumed bulk sensitive take-off angle of 0°. This methodology provides a surface enrichment factor of the molecular ions and clearly serves as an experimental evidence for recently debated surface layering and/or island structure in ionic liquid systems.
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Affiliation(s)
- Erdinc Oz
- Department of Chemistry, Bilkent University, 06800, Ankara, Turkey
| | - Ozgur Sahin
- Department of Chemistry, Bilkent University, 06800, Ankara, Turkey
| | - Halil I Okur
- Department of Chemistry, Bilkent University, 06800, Ankara, Turkey
| | - Sefik Suzer
- Department of Chemistry, Bilkent University, 06800, Ankara, Turkey
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9
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Yang D, Huang Y, Wang X, He R, Zhou G, Chen X, Yang Z. Different Hydrogen Bond Changes Driven by Surface Segregation Behavior of Imidazolium-Based Ionic Liquid Mixture at the Liquid-Vacuum Interface. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2020; 36:11798-11808. [PMID: 32962350 DOI: 10.1021/acs.langmuir.0c01501] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
In this work, molecular dynamics (MD) simulations were carried out to study the behaviors of a binary ionic liquid (IL) mixture consisting of equimolar [C2C1Im][BF4] and [C4C1Im][BF4], as well as two corresponding pure ILs, at the liquid-vacuum interface. Our simulation results show that the competition of nonpolar interactions between different alkyl chains of two cations results in an obvious surface segregation behavior of the IL mixture at the interface, indicating an enhanced aggregation of the [C4C1Im]+ cations but a weakened aggregation of the [C2C1Im]+ cations at the outermost surface. More interestingly, different hydrogen bond (HB) changes between two imidazolium cations at the interface can be driven by such surface segregation behavior, where the [C2C1Im]+ cations rather than the [C4C1Im]+ ones have more and stronger HBs with the [BF4]- anions by comparison with the corresponding pure ILs at the interface. Meanwhile, it is interesting to find that such a stronger HB would lower the rotations of the imidazolium rings of interfacial [C2C1Im]+ cations. By contrast, the [C4C1Im]+ cations at the outermost surface rotate faster owing to their weaker HB. In addition, the orientation analysis uncovers that there is a major decrease for the orderliness of interfacial [C2C1Im]+ cations, but a minor decrease for that of interfacial [C4C1Im]+ cations, from the pure IL to the IL mixture. Such distinct results are closely related to the surface segregation between the [C2C1Im]+ and [C4C1Im]+ cations in the IL mixture and their interfacial HB properties. Thus, our simulation results afford a deep insight into the surface segregation effect on the HB behavior of the imidazolium-based IL mixture at liquid-vacuum interface.
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Affiliation(s)
- Deshuai Yang
- Institute of Advanced Materials (IAM), State-Province Joint Engineering Laboratory of Zeolite Membrane Materials, College of Chemistry and Chemical Engineering, Jiangxi Normal University, Nanchang 330022, People's Republic of China
| | - Yiping Huang
- Institute of Advanced Materials (IAM), State-Province Joint Engineering Laboratory of Zeolite Membrane Materials, College of Chemistry and Chemical Engineering, Jiangxi Normal University, Nanchang 330022, People's Republic of China
- School of Chemistry and Chemical Engineering, Southeast University, Nanjing 211189, People's Republic of China
| | - Xueping Wang
- Institute of Advanced Materials (IAM), State-Province Joint Engineering Laboratory of Zeolite Membrane Materials, College of Chemistry and Chemical Engineering, Jiangxi Normal University, Nanchang 330022, People's Republic of China
| | - Ruiyao He
- Institute of Advanced Materials (IAM), State-Province Joint Engineering Laboratory of Zeolite Membrane Materials, College of Chemistry and Chemical Engineering, Jiangxi Normal University, Nanchang 330022, People's Republic of China
| | - Guobing Zhou
- Institute of Advanced Materials (IAM), State-Province Joint Engineering Laboratory of Zeolite Membrane Materials, College of Chemistry and Chemical Engineering, Jiangxi Normal University, Nanchang 330022, People's Republic of China
| | - Xiangshu Chen
- Institute of Advanced Materials (IAM), State-Province Joint Engineering Laboratory of Zeolite Membrane Materials, College of Chemistry and Chemical Engineering, Jiangxi Normal University, Nanchang 330022, People's Republic of China
| | - Zhen Yang
- Institute of Advanced Materials (IAM), State-Province Joint Engineering Laboratory of Zeolite Membrane Materials, College of Chemistry and Chemical Engineering, Jiangxi Normal University, Nanchang 330022, People's Republic of China
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10
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Huang Q, Huang Y, Luo Y, Li L, Zhou G, Chen X, Yang Z. Molecular-level insights into the structures, dynamics, and hydrogen bonds of ethylammonium nitrate protic ionic liquid at the liquid-vacuum interface. Phys Chem Chem Phys 2020; 22:13780-13789. [PMID: 32538411 DOI: 10.1039/d0cp00736f] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
A series of molecular dynamics simulations have been used to systematically explore the structures, dynamics and hydrogen bonds (HBs) of ethylammonium nitrate (EAN) protic ionic liquid (IL) and their mutual relationship at the liquid-vacuum interface. The simulation results clearly demonstrate that there exists a sandwich structure at the interface, with the double-layer of the EA+ cations on both sides and one intercalated layer of the NO3- anions in the middle. Wherein, the outermost cation layer prefers the orientation with the CH3 groups pointing to the vacuum phase due to the hydrophobic interactions, while the CH3 groups in the second layer direct to the bulk liquid phase owing to the HB formation between their NH3+ groups and the intercalated NO3- anions in the middle layer. On the other hand, the continuous HB strength of the cations in the outermost layer (denoted as Cation-1) is found to be almost identical with the counterpart of the cations in the second layer (denoted as Cation-2), whereas the intermittent HB strength of Cation-1 is much larger than that of Cation-2 at all temperatures. Furthermore, the rotational motion of Cation-1 with the normal vector of the C-C-N plane in the cation is faster than that of Cation-2 with the same vector, resulting from more free space in the outermost layer. On the contrary, the rotational motion of Cation-1 with the vector from the mass center of the cation to its N atom is much slower than that of Cation-2 with the same vector, which can be attributed to the combined effects of the stronger intermittent HBs of Cation-1 and the hydrophobic interactions of its CH3 group in the outermost layer.
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Affiliation(s)
- Qin Huang
- Institute of Advanced Materials (IAM), State-Province Joint Engineering Laboratory of Zeolite Membrane Materials, College of Chemistry and Chemical Engineering, Jiangxi Normal University, Nanchang 330022, People's Republic of China.
| | - Yiping Huang
- Institute of Advanced Materials (IAM), State-Province Joint Engineering Laboratory of Zeolite Membrane Materials, College of Chemistry and Chemical Engineering, Jiangxi Normal University, Nanchang 330022, People's Republic of China. and School of Chemistry and Chemical Engineering, Southeast University, Nanjing 211189, People's Republic of China
| | - Yi Luo
- Institute of Advanced Materials (IAM), State-Province Joint Engineering Laboratory of Zeolite Membrane Materials, College of Chemistry and Chemical Engineering, Jiangxi Normal University, Nanchang 330022, People's Republic of China.
| | - Li Li
- Institute of Advanced Materials (IAM), State-Province Joint Engineering Laboratory of Zeolite Membrane Materials, College of Chemistry and Chemical Engineering, Jiangxi Normal University, Nanchang 330022, People's Republic of China.
| | - Guobing Zhou
- Institute of Advanced Materials (IAM), State-Province Joint Engineering Laboratory of Zeolite Membrane Materials, College of Chemistry and Chemical Engineering, Jiangxi Normal University, Nanchang 330022, People's Republic of China.
| | - Xiangshu Chen
- Institute of Advanced Materials (IAM), State-Province Joint Engineering Laboratory of Zeolite Membrane Materials, College of Chemistry and Chemical Engineering, Jiangxi Normal University, Nanchang 330022, People's Republic of China.
| | - Zhen Yang
- Institute of Advanced Materials (IAM), State-Province Joint Engineering Laboratory of Zeolite Membrane Materials, College of Chemistry and Chemical Engineering, Jiangxi Normal University, Nanchang 330022, People's Republic of China.
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11
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Smoll EJ, Purcell SM, D'Andrea L, Slattery JM, Bruce DW, Costen ML, McKendrick KG, Minton TK. Probing Conformational Heterogeneity at the Ionic Liquid-Vacuum Interface by Reactive-Atom Scattering. J Phys Chem Lett 2019; 10:156-163. [PMID: 30537842 DOI: 10.1021/acs.jpclett.8b02920] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
The atomic-level description of liquid interfaces has lagged behind that of solid crystalline surfaces because existing experimental techniques have been limited in their capability to report molecular structure in a fluctuating liquid interfacial layer. We have moved toward a more detailed experimental description of the gas-liquid interface by studying the F-atom scattering dynamics on a common ionic liquid, 1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide. When given contrast by deuterium labeling, the yield and dynamical behavior of reactively scattered HF isotopologues can resolve distinct signatures from the cation butyl, methyl, and ring groups, which help to quantify the relative populations of cation conformations at the liquid-vacuum interface. These results demonstrate the importance of molecular organization in driving site-specific reactions at the extreme outer regions of the gas-liquid interface.
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Affiliation(s)
- Eric J Smoll
- Department of Chemistry and Biochemistry , Montana State University , Bozeman , Montana 59717 , United States
| | - Simon M Purcell
- Institute of Chemical Sciences, School of Engineering and Physical Sciences , Heriot-Watt University , Edinburgh EH14 4AS , U.K
| | - Lucia D'Andrea
- Department of Chemistry , University of York , Heslington , York YO10 5DD , U.K
| | - John M Slattery
- Department of Chemistry , University of York , Heslington , York YO10 5DD , U.K
| | - Duncan W Bruce
- Department of Chemistry , University of York , Heslington , York YO10 5DD , U.K
| | - Matthew L Costen
- Institute of Chemical Sciences, School of Engineering and Physical Sciences , Heriot-Watt University , Edinburgh EH14 4AS , U.K
| | - Kenneth G McKendrick
- Institute of Chemical Sciences, School of Engineering and Physical Sciences , Heriot-Watt University , Edinburgh EH14 4AS , U.K
| | - Timothy K Minton
- Department of Chemistry and Biochemistry , Montana State University , Bozeman , Montana 59717 , United States
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12
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Khalifa Y, Broderick A, Newberg JT. Surface enhancement of water at the ionic liquid-gas interface of [HMIM][Cl] under ambient water vapor. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2018; 30:325001. [PMID: 29972140 DOI: 10.1088/1361-648x/aad102] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
The ionic liquid-gas interface of 1-hexyl-3-methyl-imidazolium chloride, [HMIM][Cl], was examined in the presence of water vapor using lab-based ambient pressure x-ray photoelectron spectroscopy (APXPS) at room temperature. The interfacial water uptake was measured quantitatively in the pressure range of high vacuum up to a maximum of 5 Torr (27% RH) and back to high vacuum in a systematic manner. Water mole fractions in the interface determined from APXPS were compared to previously published tandem differential mobility analysis results on [HMIM][Cl] nanodroplets. Our findings show that water constitutes a significantly larger mole fraction at the interface when compared to the bulk. Additionally, the reverse isotherms showed that the uptake of water at the interface of [HMIM][Cl] is a reversible process.
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Affiliation(s)
- Yehia Khalifa
- Department of Chemistry and Biochemistry, University of Delaware, Newark, DE 19716, United States of America
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13
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Abstract
There is no doubt that ionic liquids have become a major subject of study for modern chemistry. We have become used to ever more publications in the field each year, although there is some evidence that this is beginning to plateau at approximately 3500 papers each year. They have been the subject of several major reviews and books, dealing with different applications and aspects of their behaviours. In this article, I will show a little of how interest in ionic liquids grew and developed.
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Affiliation(s)
- Tom Welton
- Department of Chemistry, Imperial College London, Exhibition Road, London, SW7 2AZ, England.
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14
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Haddad J, Pontoni D, Murphy BM, Festersen S, Runge B, Magnussen OM, Steinrück HG, Reichert H, Ocko BM, Deutsch M. Surface structure evolution in a homologous series of ionic liquids. Proc Natl Acad Sci U S A 2018; 115:E1100-E1107. [PMID: 29358372 PMCID: PMC5819424 DOI: 10.1073/pnas.1716418115] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Interfaces of room temperature ionic liquids (RTILs) are important for both applications and basic science and are therefore intensely studied. However, the evolution of their interface structure with the cation's alkyl chain length [Formula: see text] from Coulomb to van der Waals interaction domination has not yet been studied for even a single broad homologous RTIL series. We present here such a study of the liquid-air interface for [Formula: see text], using angstrom-resolution X-ray methods. For [Formula: see text], a typical "simple liquid" monotonic surface-normal electron density profile [Formula: see text] is obtained, like those of water and organic solvents. For [Formula: see text], increasingly more pronounced nanoscale self-segregation of the molecules' charged moieties and apolar chains yields surface layering with alternating regions of headgroups and chains. The layering decays into the bulk over a few, to a few tens, of nanometers. The layering periods and decay lengths, their linear [Formula: see text] dependence, and slopes are discussed within two models, one with partial-chain interdigitation and the other with liquid-like chains. No surface-parallel long-range order is found within the surface layer. For [Formula: see text], a different surface phase is observed above melting. Our results also impact general liquid-phase issues like supramolecular self-aggregation and bulk-surface structure relations.
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Affiliation(s)
- Julia Haddad
- Physics Department, Bar-Ilan University, Ramat Gan 5290002, Israel
- Institute of Nanotechnology and Advanced Materials, Bar-Ilan University, Ramat Gan 5290002, Israel
| | - Diego Pontoni
- European Synchrotron Radiation Facility, The European Synchrotron and Partnership for Soft Condensed Matter (PSCM), 38000 Grenoble, France
| | - Bridget M Murphy
- Institute for Experimental and Applied Physics, Kiel University, 24118 Kiel, Germany
- Ruprecht Haensel Laboratory, Kiel University, 24098 Kiel, Germany
| | - Sven Festersen
- Institute for Experimental and Applied Physics, Kiel University, 24118 Kiel, Germany
| | - Benjamin Runge
- Institute for Experimental and Applied Physics, Kiel University, 24118 Kiel, Germany
| | - Olaf M Magnussen
- Institute for Experimental and Applied Physics, Kiel University, 24118 Kiel, Germany
- Ruprecht Haensel Laboratory, Kiel University, 24098 Kiel, Germany
| | - Hans-Georg Steinrück
- Stanford Synchrotron Radiation Laboratory (SSRL) Materials Science Division, Stanford Linear Accelerator Center (SLAC) National Accelerator Laboratory, Menlo Park, CA 94025
| | - Harald Reichert
- European Synchrotron Radiation Facility, The European Synchrotron, 38000 Grenoble, France
| | - Benjamin M Ocko
- National Synchrotron Light Source II (NSLS-II), Brookhaven National Laboratory, Upton, NY 11973
| | - Moshe Deutsch
- Physics Department, Bar-Ilan University, Ramat Gan 5290002, Israel;
- Institute of Nanotechnology and Advanced Materials, Bar-Ilan University, Ramat Gan 5290002, Israel
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15
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Mars J, Hou B, Weiss H, Li H, Konovalov O, Festersen S, Murphy BM, Rütt U, Bier M, Mezger M. Surface induced smectic order in ionic liquids - an X-ray reflectivity study of [C 22C 1im] +[NTf 2] . Phys Chem Chem Phys 2018; 19:26651-26661. [PMID: 28960006 DOI: 10.1039/c7cp04852a] [Citation(s) in RCA: 32] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
Surface induced smectic order was found for the ionic liquid 1-methyl-3-docosylimidazolium bis(trifluoromethlysulfonyl)imide by X-ray reflectivity and grazing incidence scattering experiments. Near the free liquid surface, an ordered structure of alternating layers composed of polar and non-polar moieties is observed. This leads to an oscillatory interfacial profile perpendicular to the liquid surface with a periodicity of 3.7 nm. Small angle X-ray scattering and polarized light microscopy measurements suggest that the observed surface structure is related to fluctuations into a metastable liquid crystalline SmA2 phase that was found by supercooling the bulk liquid. The observed surface ordering persists up to 157 °C, i.e. more than 88 K above the bulk melting temperature of 68.1 °C. Close to the bulk melting point, we find a thickness of the ordered layer of L = 30 nm. The dependency of L(τ) = Λ ln(τ/τ1) vs. reduced temperature τ follows a logarithmic growth law. In agreement with theory, the pre-factor Λ is governed by the correlation length of the isotropic bulk phase.
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Affiliation(s)
- Julian Mars
- Max Planck Institute for Polymer Research, Ackermannweg 10, 55128 Mainz, Germany.
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16
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Huang W, Zheng D, Xia C, Feng L, Dong L, Jiang P. Affinity regulation of the NH 3 + H 2O system by ionic liquids with molecular interaction analysis. Phys Chem Chem Phys 2018; 19:16242-16250. [PMID: 28607984 DOI: 10.1039/c7cp01757j] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
This work proposed using an adequate ionic liquid (IL) to weaken the affinity between NH3 and H2O as a potential solution to the issue of high-energy consumption involved in separating NH3 gas from liquid H2O. Two quaternary phosphonium-based ILs were selected according to an optimized regulation strategy. The regulation effects of the ILs were evaluated by the vapor-liquid equilibrium property of the NH3 + H2O + IL systems, and were compared with the regulation effects of traditional additives. The results showed that the expected effects were achieved by adding ILs. The regulation mechanisms of different strategies were discussed with respect to the molecular structure and chemical equilibrium for the first time limited to the authors' latest literature review. Finally, the IR spectra of the NH3 + H2O + IL systems were acquired and analyzed to verify the interactions of the ILs with NH3 and H2O.
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Affiliation(s)
- Weijia Huang
- Department of Thermal Engineering, Tsinghua University, Beijing 100084, China
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17
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Camci MT, Aydogan P, Ulgut B, Kocabas C, Suzer S. XPS enables visualization of electrode potential screening in an ionic liquid medium with temporal- and lateral-resolution. Phys Chem Chem Phys 2018; 18:28434-28440. [PMID: 27757457 DOI: 10.1039/c6cp04933h] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
We present an X-ray photoelectron spectroscopic (XPS) investigation of potential screening across two gold electrodes fabricated on a porous polymer surface which is impregnated with the ionic liquid (IL) N-N-diethyl-N-methyl-N-(2-methoxyethyl)ammonium bis(trifluoromethanesulfonyl)imide [DEME-TFSI]. The IL provides a sheet of conducting layers to the insulating polymer film, and allows monitoring charging and screening dynamics at the polymer + IL/vacuum interface in a laterally resolved fashion across the electrodes. Time-resolved measurements are also implemented by recording F1s peaks of the IL, while imposing 10 mHz square-wave (SQW) pulses across the two electrodes in a source-drain geometry. Variations in the F1s binding energy reflect directly the transient local electrical potential, and allow us to visualize screening of the otherwise built-in local voltage drop on and across the metal electrodes in the range of millimeters. Accordingly, the device is partitioned into two oppositely polarized regions, each following polarization of one electrode through the IL medium. On the other extreme, upon imposing relatively fast 1 kHz SQW pulses the charge screening is prevented and the device is brought to assume a simple resistor role. A simple equivalent circuit model also reproduces the observed voltage transients qualitatively. The presented structure and variants of XPS measurements, enabling us to record voltage transients in unexpectedly large lateral distances away from the electrodes, can impact the understanding of various electrochemical concepts.
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Affiliation(s)
- M T Camci
- Department of Chemistry, Bilkent University, Ankara 06800, Turkey.
| | - P Aydogan
- Department of Chemistry, Bilkent University, Ankara 06800, Turkey.
| | - B Ulgut
- Department of Chemistry, Bilkent University, Ankara 06800, Turkey.
| | - C Kocabas
- Department of Physics, Bilkent University, Ankara 06800, Turkey
| | - S Suzer
- Department of Chemistry, Bilkent University, Ankara 06800, Turkey.
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18
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Yang D, Fu F, Li L, Yang Z, Wan Z, Luo Y, Hu N, Chen X, Zeng G. Unique orientations and rotational dynamics of a 1-butyl-3-methyl-imidazolium hexafluorophosphate ionic liquid at the gas–liquid interface: the effects of the hydrogen bond and hydrophobic interactions. Phys Chem Chem Phys 2018; 20:12043-12052. [DOI: 10.1039/c8cp00839f] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Two-stage rotational motions of the interfacial [BMIM]+ cations are essentially determined by both hydrophobic and hydrogen-bonding interactions.
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Affiliation(s)
- Deshuai Yang
- Institute of Advanced Materials (IAM), State-Province Joint Engineering Laboratory of Zeolite Membrane Materials, College of Chemistry and Chemical Engineering, Jiangxi Normal University
- Nanchang 330022
- People's Republic of China
- Kuang Yaming Honors School, Nanjing University
- Nanjing 210023
| | - Fangjia Fu
- Institute of Advanced Materials (IAM), State-Province Joint Engineering Laboratory of Zeolite Membrane Materials, College of Chemistry and Chemical Engineering, Jiangxi Normal University
- Nanchang 330022
- People's Republic of China
| | - Li Li
- Institute of Advanced Materials (IAM), State-Province Joint Engineering Laboratory of Zeolite Membrane Materials, College of Chemistry and Chemical Engineering, Jiangxi Normal University
- Nanchang 330022
- People's Republic of China
| | - Zhen Yang
- Institute of Advanced Materials (IAM), State-Province Joint Engineering Laboratory of Zeolite Membrane Materials, College of Chemistry and Chemical Engineering, Jiangxi Normal University
- Nanchang 330022
- People's Republic of China
| | - Zheng Wan
- Institute of Advanced Materials (IAM), State-Province Joint Engineering Laboratory of Zeolite Membrane Materials, College of Chemistry and Chemical Engineering, Jiangxi Normal University
- Nanchang 330022
- People's Republic of China
| | - Yi Luo
- Institute of Advanced Materials (IAM), State-Province Joint Engineering Laboratory of Zeolite Membrane Materials, College of Chemistry and Chemical Engineering, Jiangxi Normal University
- Nanchang 330022
- People's Republic of China
| | - Na Hu
- Institute of Advanced Materials (IAM), State-Province Joint Engineering Laboratory of Zeolite Membrane Materials, College of Chemistry and Chemical Engineering, Jiangxi Normal University
- Nanchang 330022
- People's Republic of China
| | - Xiangshu Chen
- Institute of Advanced Materials (IAM), State-Province Joint Engineering Laboratory of Zeolite Membrane Materials, College of Chemistry and Chemical Engineering, Jiangxi Normal University
- Nanchang 330022
- People's Republic of China
| | - Guixiang Zeng
- Kuang Yaming Honors School, Nanjing University
- Nanjing 210023
- People's Republic of China
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19
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Sedghamiz E, Moosavi M. Probing the tricationic ionic liquid/vacuum interface: insights from molecular dynamics simulations. Phys Chem Chem Phys 2018; 20:14251-14263. [DOI: 10.1039/c8cp02471e] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The surface properties of three symmetric linear tricationic ionic liquids (LTILs) with the common anion, bis(trifluoromethylsulfonyl)imide ([NTf2]−), were studied using atomistic molecular dynamics simulation and identification of the truly interfacial molecules (ITIM) analysis.
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Affiliation(s)
- Elaheh Sedghamiz
- Department of Chemistry
- University of Isfahan
- Isfahan 81746-73441
- Iran
| | - Majid Moosavi
- Department of Chemistry
- University of Isfahan
- Isfahan 81746-73441
- Iran
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20
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Lovelock KRJ. Quantifying intermolecular interactions of ionic liquids using cohesive energy densities. ROYAL SOCIETY OPEN SCIENCE 2017; 4:171223. [PMID: 29308254 PMCID: PMC5750021 DOI: 10.1098/rsos.171223] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/24/2017] [Accepted: 10/30/2017] [Indexed: 05/25/2023]
Abstract
For ionic liquids (ILs), both the large number of possible cation + anion combinations and their ionic nature provide a unique challenge for understanding intermolecular interactions. Cohesive energy density, ced, is used to quantify the strength of intermolecular interactions for molecular liquids, and is determined using the enthalpy of vaporization. A critical analysis of the experimental challenges and data to obtain ced for ILs is provided. For ILs there are two methods to judge the strength of intermolecular interactions, due to the presence of multiple constituents in the vapour phase of ILs. Firstly, cedIP, where the ionic vapour constituent is neutral ion pairs, the major constituent of the IL vapour. Secondly, cedC+A, where the ionic vapour constituents are isolated ions. A cedIP dataset is presented for 64 ILs. For the first time an experimental cedC+A, a measure of the strength of the total intermolecular interaction for an IL, is presented. cedC+A is significantly larger for ILs than ced for most molecular liquids, reflecting the need to break all of the relatively strong electrostatic interactions present in ILs. However, the van der Waals interactions contribute significantly to IL volatility due to the very strong electrostatic interaction in the neutral ion pair ionic vapour. An excellent linear correlation is found between cedIP and the inverse of the molecular volume. A good linear correlation is found between IL cedIP and IL Gordon parameter (which are dependent primarily on surface tension). ced values obtained through indirect methods gave similar magnitude values to cedIP. These findings show that cedIP is very important for understanding IL intermolecular interactions, in spite of cedIP not being a measure of the total intermolecular interactions of an IL. In the outlook section, remaining challenges for understanding IL intermolecular interactions are outlined.
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21
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Pontoni D, Haddad J, Di Michiel M, Deutsch M. Self-segregated nanostructure in room temperature ionic liquids. SOFT MATTER 2017; 13:6947-6955. [PMID: 28849840 DOI: 10.1039/c7sm01464c] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
The nanosegregated bulk structure, and its evolution with the cation's alkyl length n, are studied by X-ray scattering for an unprecedentedly broad homologous series of a model room-temperature ionic liquid, [CnMIM][NTf2] (n = 4-22). A tri-periodic local structure is found, with the lateral periodicities, dII and dIII independent of n, and a longitudinal one, dI, linearly increasing with n. The results are consistent with a local structure comprising alternating layers of polar headgroups and apolar, interdigitated, partly overlapping, cations' alkyl tails, of an average macroscopic mass density close to that of liquid alkanes. A slope decrease in the linear dI(n) suggests a change from a lower to a higher rate of increase with n of chain overlap for n ≥ 12. The order decay lengths of the layering, and of the lateral chain packing, increase with n, as expected from the increasing van der Waals interaction's domination of the structure. The headgroups' lateral packing decay length decreases with n, due to increasing frustration between the longer lateral periodicity preferred by the headgroups, and the shorter lateral periodicity preferred by the chains. A comparison of the bulk and surface structures highlights the surface's ordering effect, which, however, does not induce here a surface phase different from the bulk, as it does in liquid crystals and liquid alkanes.
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Affiliation(s)
- Diego Pontoni
- ESRF - The European Synchrotron and Partnership for Soft Condensed Matter (PSCM), 71 Avenue des Martyrs, 38000 Grenoble, France
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22
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Bruce DW, Cabry CP, Lopes JNC, Costen ML, D'Andrea L, Grillo I, Marshall BC, McKendrick KG, Minton TK, Purcell SM, Rogers S, Slattery JM, Shimizu K, Smoll E, Tesa-Serrate MA. Nanosegregation and Structuring in the Bulk and at the Surface of Ionic-Liquid Mixtures. J Phys Chem B 2017; 121:6002-6020. [PMID: 28459567 DOI: 10.1021/acs.jpcb.7b01654] [Citation(s) in RCA: 68] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Ionic-liquid (IL) mixtures hold great promise, as they allow liquids with a wide range of properties to be formed by mixing two common components rather than by synthesizing a large array of pure ILs with different chemical structures. In addition, these mixtures can exhibit a range of properties and structural organization that depend on their composition, which opens up new possibilities for the composition-dependent control of IL properties for particular applications. However, the fundamental properties, structure, and dynamics of IL mixtures are currently poorly understood, which limits their more widespread application. This article presents the first comprehensive investigation into the bulk and surface properties of IL mixtures formed from two commonly encountered ILs: 1-ethyl-3-methylimidazolium and 1-dodecyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ([C2mim][Tf2N] and [C12mim][Tf2N]). Physical property measurements (viscosity, conductivity, and density) reveal that these IL mixtures are not well described by simple mixing laws, implying that their structure and dynamics are strongly composition dependent. Small-angle X-ray and neutron scattering measurements, alongside molecular dynamics (MD) simulations, show that at low mole fractions of [C12mim][Tf2N], the bulk of the IL is composed of small aggregates of [C12mim]+ ions in a [C2mim][Tf2N] matrix, which is driven by nanosegregation of the long alkyl chains and the polar parts of the IL. As the proportion of [C12mim][Tf2N] in the mixtures increases, the size and number of aggregates increases until the C12 alkyl chains percolate through the system and a bicontinuous network of polar and nonpolar domains is formed. Reactive atom scattering-laser-induced fluorescence experiments, also supported by MD simulations, have been used to probe the surface structure of these mixtures. It is found that the vacuum-IL interface is enriched significantly in C12 alkyl chains, even in mixtures low in the long-chain component. These data show, in contrast to previous suggestions, that the [C12mim]+ ion is surface active in this binary IL mixture. However, the surface does not become saturated in C12 chains as its proportion in the mixtures increases and remains unsaturated in pure [C12mim][Tf2N].
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Affiliation(s)
- Duncan W Bruce
- Department of Chemistry, University of York , Heslington, York YO10 5DD, U.K
| | - Christopher P Cabry
- Department of Chemistry, University of York , Heslington, York YO10 5DD, U.K
| | - José N Canongia Lopes
- Centro de Química Estrutural, IST, Universidade de Lisboa , 1049-001 Lisboa, Portugal.,ITQB, Universidade Nova de Lisboa , Avenida República, 2780-157 Oeiras, Portugal
| | - Matthew L Costen
- Institute of Chemical Sciences, Heriot-Watt University , Edinburgh EH14 4AS, U.K
| | - Lucía D'Andrea
- Department of Chemistry, University of York , Heslington, York YO10 5DD, U.K
| | - Isabelle Grillo
- ILL , 71 Avenue des Martyrs, CS 20156, 38042 Grenoble Cedex 9, France
| | - Brooks C Marshall
- Department of Chemistry and Biochemistry, Montana State University , Bozeman, Montana 59717, United States
| | - Kenneth G McKendrick
- Institute of Chemical Sciences, Heriot-Watt University , Edinburgh EH14 4AS, U.K
| | - Timothy K Minton
- Department of Chemistry and Biochemistry, Montana State University , Bozeman, Montana 59717, United States
| | - Simon M Purcell
- Institute of Chemical Sciences, Heriot-Watt University , Edinburgh EH14 4AS, U.K
| | - Sarah Rogers
- ISIS, Science & Technology Facilities Council, Rutherford Appleton Laboratory , OX11 0QX Chilton, U.K
| | - John M Slattery
- Department of Chemistry, University of York , Heslington, York YO10 5DD, U.K
| | - Karina Shimizu
- Centro de Química Estrutural, IST, Universidade de Lisboa , 1049-001 Lisboa, Portugal.,ITQB, Universidade Nova de Lisboa , Avenida República, 2780-157 Oeiras, Portugal
| | - Eric Smoll
- Department of Chemistry and Biochemistry, Montana State University , Bozeman, Montana 59717, United States
| | - María A Tesa-Serrate
- Institute of Chemical Sciences, Heriot-Watt University , Edinburgh EH14 4AS, U.K
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23
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24
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Biedron AB, Garfunkel EL, Castner EW, Rangan S. Ionic liquid ultrathin films at the surface of Cu(100) and Au(111). J Chem Phys 2017; 146:054704. [DOI: 10.1063/1.4975101] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Affiliation(s)
- Aleksandra B. Biedron
- Department of Chemistry and Chemical Biology, Rutgers University, 610 Taylor Road, Piscataway, New Jersey 08854, USA
| | - Eric L. Garfunkel
- Department of Chemistry and Chemical Biology, Rutgers University, 610 Taylor Road, Piscataway, New Jersey 08854, USA
| | - Edward W. Castner
- Department of Chemistry and Chemical Biology, Rutgers University, 610 Taylor Road, Piscataway, New Jersey 08854, USA
| | - Sylvie Rangan
- Department of Physics and Astronomy and Laboratory for Surface Modification, Rutgers University, 136 Frelinghuysen Road, Piscataway, New Jersey 08854, USA
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25
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Weiss H, Mars J, Li H, Kircher G, Ivanova O, Feoktystov A, Soltwedel O, Bier M, Mezger M. Mesoscopic Correlation Functions in Heterogeneous Ionic Liquids. J Phys Chem B 2017; 121:620-629. [PMID: 28001074 DOI: 10.1021/acs.jpcb.6b11220] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
A common feature of ionic liquids composed of cations with long aliphatic side chains is structural heterogeneities on the nanometer length scale. This so-called microphase separation arises from the clustering of aliphatic moieties. The temperature dependence of the liquid bulk structure was studied by small-angle X-ray and neutron scattering for a set of methylimidazolium ([C18C1im]+, [C22C1im]+) based ionic liquids with tris(pentafluoroethyl)trifluorophosphate ([FAP]-), bis(trifluoromethylsulfonyl)imide ([NTf2]-), and bis(nonafluorobutylsulfonyl)imide ([NNf2]-) anions. The experimental data is quantitatively analyzed using a generalized Teubner-Strey model. Discussion of the resulting periodicity d and correlation length ξ shows that the structural heterogeneities are governed by the interplay between the alkyl chain length, the geometry of the anion, and entropic effects. Connections between the mesoscopic correlation functions, density, and entropy of fusion are discussed in comparison to alcohols. The observed dependencies allow predictions on the mesoscopic correlation functions based on macroscopic bulk quantities.
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Affiliation(s)
- Henning Weiss
- Max Planck Institute for Polymer Research , Ackermannweg 10, 55128 Mainz, Germany
| | - Julian Mars
- Max Planck Institute for Polymer Research , Ackermannweg 10, 55128 Mainz, Germany.,Institute of Physics, Johannes Gutenberg University Mainz , 55128 Mainz, Germany
| | - Hailong Li
- Max Planck Institute for Polymer Research , Ackermannweg 10, 55128 Mainz, Germany
| | - Gunnar Kircher
- Max Planck Institute for Polymer Research , Ackermannweg 10, 55128 Mainz, Germany
| | - Oxana Ivanova
- Jülich Centre for Neutron Science (JCNS) at Heinz Maier-Leibnitz Zentrum (MLZ), Forschungszentrum Jülich GmbH , Lichtenbergstr. 1, 85748 Garching, Germany
| | - Artem Feoktystov
- Jülich Centre for Neutron Science (JCNS) at Heinz Maier-Leibnitz Zentrum (MLZ), Forschungszentrum Jülich GmbH , Lichtenbergstr. 1, 85748 Garching, Germany
| | - Olaf Soltwedel
- Max Planck Institute for Solid State Research , Outstation at Heinz Maier-Leibnitz Zentrum, Lichtenbergstr. 1, 85747 Garching, Germany
| | - Markus Bier
- Max Planck Institute for Intelligent Systems , Heisenbergstr. 3, 70569 Stuttgart, Germany.,Institute for Theoretical Physics IV, University of Stuttgart , Pfaffenwaldring 57, 70569 Stuttgart, Germany
| | - Markus Mezger
- Max Planck Institute for Polymer Research , Ackermannweg 10, 55128 Mainz, Germany.,Institute of Physics, Johannes Gutenberg University Mainz , 55128 Mainz, Germany
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Fogarty RM, Matthews RP, Clough MT, Ashworth CR, Brandt-Talbot A, Corbett PJ, Palgrave RG, Bourne RA, Chamberlain TW, Vander Hoogerstraete T, Thompson PBJ, Hunt PA, Besley NA, Lovelock KRJ. NEXAFS spectroscopy of ionic liquids: experiments versus calculations. Phys Chem Chem Phys 2017; 19:31156-31167. [DOI: 10.1039/c7cp07143d] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Experimental N 1s and S 1s NEXAFS spectra are compared to TD-DFT calculated spectra for 12 ionic liquids.
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Affiliation(s)
| | | | | | | | | | - Paul J. Corbett
- Department of Chemical Engineering, Imperial College London
- UK
| | | | - Richard A. Bourne
- School of Chemical and Process Engineering
- University of Leeds
- UK
- Institute of Process Research and Development
- School of Chemistry
| | - Thomas W. Chamberlain
- Institute of Process Research and Development
- School of Chemistry
- University of Leeds
- UK
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Nakajima K, Nakanishi S, Chval Z, Lísal M, Kimura K. Surface segregation in a binary mixture of ionic liquids: Comparison between high-resolution RBS measurements and moleculardynamics simulations. J Chem Phys 2016; 145:184704. [PMID: 27846689 DOI: 10.1063/1.4967260] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Affiliation(s)
- Kaoru Nakajima
- Department of Micro Engineering, Kyoto University, Kyoto-daigaku-katsura, Nishikyo, Kyoto 615-8540, Japan
| | - Shunto Nakanishi
- Department of Micro Engineering, Kyoto University, Kyoto-daigaku-katsura, Nishikyo, Kyoto 615-8540, Japan
| | - Zdeněk Chval
- Faculty of Health and Social Studies, University of South Bohemia, České Budějovice, Czech Republic
| | - Martin Lísal
- Laboratory of Aerosols Chemistry and Physics, Institute of Chemical Process Fundamentals of the CAS, v. v. i., 165 02 Prague 6-Suchdol, Czech Republic
| | - Kenji Kimura
- Department of Micro Engineering, Kyoto University, Kyoto-daigaku-katsura, Nishikyo, Kyoto 615-8540, Japan
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28
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Nakajima K, Zolboo E, Ohashi T, Lísal M, Kimura K. Perfect Composition Depth Profiling of Ionic Liquid Surfaces Using High-resolution RBS/ERDA. ANAL SCI 2016; 32:1089-1094. [PMID: 27725609 DOI: 10.2116/analsci.32.1089] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
In order to reveal the surface structures of large molecular ionic liquids (ILs), the near-surface elemental depth distributions of 1-alkyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide ([CnC1Im][Tf2N], n = 2, 6, 10) were studied using high-resolution Rutherford backscattering spectroscopy (HRBS) in combination with high-resolution elastic recoil detection analysis (HR-ERDA). The elemental depth profiles of all constituent elements, including hydrogen, were derived from HR-ERDA/HRBS measurements, so that the profiles would reproduce both HR-ERDA and HRBS spectra simultaneously. The derived elemental depth profiles agree with state-of-the-art molecular dynamics simulations, indicating the feasibility of this method. A controversy concerning the preferential orientation of [C2C1Im] at the surface has been resolved by this new combination analysis; namely, the [C2C1Im] cation has a preferential orientation with the ethyl chain pointing towards the vacuum in the topmost molecular layer.
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29
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Purcell SM, Tesa-Serrate MA, Marshall BC, Bruce DW, D'Andrea L, Costen ML, Slattery JM, Smoll EJ, Minton TK, McKendrick KG. Reactive-Atom Scattering from Liquid Crystals at the Liquid-Vacuum Interface: [C 12mim][BF 4] and 4-Cyano-4'-Octylbiphenyl (8CB). LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2016; 32:9938-9949. [PMID: 27603521 DOI: 10.1021/acs.langmuir.6b02440] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
Two complementary approaches were used to study the liquid-vacuum interface of the liquid-crystalline ionic liquid 1-dodecyl-3-methylimidazolium tetrafluoroborate ([C12mim][BF4]) in the smectic A (SmA) and isotropic phases. O atoms with two distinct incident translational energies were scattered from the surface of [C12mim][BF4]. Angle-dependent time-of-flight distributions and OH yields, respectively, were recorded from high- and low-energy O atoms. There were no significant changes in the measurements using either approach, nor the properties derived from them, accompanying the transition from the SmA to the isotropic phase. This indicates that the surface structure of [C12mim][BF4] remains essentially unchanged across the phase boundary, implying that the bulk order and surface structure are not strongly correlated for this material. This effect is ascribed to the strong propensity for the outer surfaces of ionic liquids to be dominated by alkyl chains, over an underlying layer rich in anions and cation head groups, whether or not the bulk material is a liquid crystal. In a comparative study, the OH yield from the surface of the liquid crystal, 8CB, was found to be affected by the bulk order, showing a surprising step increase at the SmA-nematic transition temperature, whose origin is the subject of speculation.
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Affiliation(s)
- Simon M Purcell
- Institute of Chemical Sciences, School of Engineering and Physical Sciences, Heriot-Watt University , Edinburgh EH14 4AS, United Kingdom
| | - Maria A Tesa-Serrate
- Institute of Chemical Sciences, School of Engineering and Physical Sciences, Heriot-Watt University , Edinburgh EH14 4AS, United Kingdom
| | - Brooks C Marshall
- Department of Chemistry and Biochemistry, Montana State University , Bozeman, Montana 59717, United States
| | - Duncan W Bruce
- Department of Chemistry, University of York , Heslington, York YO10 5DD, United Kingdom
| | - Lucía D'Andrea
- Department of Chemistry, University of York , Heslington, York YO10 5DD, United Kingdom
| | - Matthew L Costen
- Institute of Chemical Sciences, School of Engineering and Physical Sciences, Heriot-Watt University , Edinburgh EH14 4AS, United Kingdom
| | - John M Slattery
- Department of Chemistry, University of York , Heslington, York YO10 5DD, United Kingdom
| | - Eric J Smoll
- Department of Chemistry and Biochemistry, Montana State University , Bozeman, Montana 59717, United States
| | - Timothy K Minton
- Department of Chemistry and Biochemistry, Montana State University , Bozeman, Montana 59717, United States
| | - Kenneth G McKendrick
- Institute of Chemical Sciences, School of Engineering and Physical Sciences, Heriot-Watt University , Edinburgh EH14 4AS, United Kingdom
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Nakajima K, Nakanishi S, Lísal M, Kimura K. Surface structure of imidazolium-based ionic liquids: Quantitative comparison between simulations and high-resolution RBS measurements. J Chem Phys 2016; 144:114702. [PMID: 27004888 DOI: 10.1063/1.4943887] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
Elemental depth profiles of 1-alkyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide ([CnMIM][TFSI], n = 4, 6, 8) are measured using high-resolution Rutherford backscattering spectroscopy (HRBS). The profiles are compared with the results of molecular dynamics (MD) simulations. Both MD simulations and HRBS measurements show that the depth profiles deviate from the uniform stoichiometric composition in the surface region, showing preferential orientations of ions at the surface. The MD simulations qualitatively reproduce the observed HRBS profiles but the agreement is not satisfactory. The observed discrepancy is ascribed to the capillary waves. By taking account of the surface roughness induced by the capillary waves, the agreement becomes almost perfect.
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Affiliation(s)
- Kaoru Nakajima
- Department of Micro Engineering, Kyoto University, Kyoto-daigaku-katsura, Nishikyo, Kyoto 615-8540, Japan
| | - Shunto Nakanishi
- Department of Micro Engineering, Kyoto University, Kyoto-daigaku-katsura, Nishikyo, Kyoto 615-8540, Japan
| | - Martin Lísal
- Laboratory of Aerosols Chemistry and Physics, Institute of Chemical Process Fundamentals of the CAS, v. v. i., Suchdol, Prague 6 165 02, Czech Republic
| | - Kenji Kimura
- Department of Micro Engineering, Kyoto University, Kyoto-daigaku-katsura, Nishikyo, Kyoto 615-8540, Japan
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31
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Hatakeyama Y, Kimura S, Kameyama T, Agawa Y, Tanaka H, Judai K, Torimoto T, Nishikawa K. Temperature-independent formation of Au nanoparticles in ionic liquids by arc plasma deposition. Chem Phys Lett 2016. [DOI: 10.1016/j.cplett.2016.06.044] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
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32
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Hatakeyama Y, Judai K, Onishi K, Takahashi S, Kimura S, Nishikawa K. Anion and cation effects on the size control of Au nanoparticles prepared by sputter deposition in imidazolium-based ionic liquids. Phys Chem Chem Phys 2016; 18:2339-49. [PMID: 26344691 DOI: 10.1039/c5cp04123f] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
The sputter deposition of metals in an ionic liquid (IL) capture medium is a simple and elegant method for preparing nanoparticles without any chemical reaction. Although there have been some reports on the size determination factors for Au nanoparticles (AuNPs) prepared using this method, the effects with respect to the type of IL used have not been clearly elucidated. This is because there are some complicating factors, some of which have been revealed by our previous systematic studies. In the present study, we prepare AuNPs in nine types of imidazolium-based IL to examine the size determination effects of the type of anion involved, the length of the alkyl chain of the cation, and the preparation temperature for each IL, while keeping other factors constant. For most of the capture media ILs, the sizes of the AuNPs increase with an increase in temperature. The AuNPs prepared in ILs containing different types of anions exhibit distinctly different particle sizes and temperature dependences. Conversely, the alkyl chain is regarded as a secondary stabilizer that works only at higher preparation temperatures. We conclude that the sizes of AuNPs prepared by this method may be determined by the competition between the collision frequency of the ejected Au atoms and the stabilizing capability of the anions that form the first coordination shell around the AuNPs. The AuNP sizes are closely related to the volume of anions.
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Affiliation(s)
- Yoshikiyo Hatakeyama
- College of Humanities and Sciences, Nihon University, Sakurajosui, Setagaya-ku, Tokyo 156-8550, Japan
| | - Ken Judai
- College of Humanities and Sciences, Nihon University, Sakurajosui, Setagaya-ku, Tokyo 156-8550, Japan
| | - Kei Onishi
- Graduate School of Advanced Integration Science, Chiba University, Yayoi-cho, Inage-ku, Chiba 263-8522, Japan.
| | - Satoshi Takahashi
- Graduate School of Advanced Integration Science, Chiba University, Yayoi-cho, Inage-ku, Chiba 263-8522, Japan.
| | - Satoshi Kimura
- Graduate School of Advanced Integration Science, Chiba University, Yayoi-cho, Inage-ku, Chiba 263-8522, Japan.
| | - Keiko Nishikawa
- Graduate School of Advanced Integration Science, Chiba University, Yayoi-cho, Inage-ku, Chiba 263-8522, Japan.
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Tesa-Serrate MA, Smoll EJ, Minton TK, McKendrick KG. Atomic and Molecular Collisions at Liquid Surfaces. Annu Rev Phys Chem 2016; 67:515-40. [PMID: 27090845 DOI: 10.1146/annurev-physchem-040215-112355] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
The gas-liquid interface remains one of the least explored, but nevertheless most practically important, environments in which molecular collisions take place. These molecular-level processes underlie many bulk phenomena of fundamental and applied interest, spanning evaporation, respiration, multiphase catalysis, and atmospheric chemistry. We review here the research that has, during the past decade or so, been unraveling the molecular-level mechanisms of inelastic and reactive collisions at the gas-liquid interface. Armed with the knowledge that such collisions with the outer layers of the interfacial region can be unambiguously distinguished, we show that the scattering of gas-phase projectiles is a promising new tool for the interrogation of liquid surfaces with extreme surface sensitivity. Especially for reactive scattering, this method also offers absolute chemical selectivity for the groups that react to produce a specific observed product.
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Affiliation(s)
- Maria A Tesa-Serrate
- Institute of Chemical Sciences, School of Engineering and Physical Sciences, Heriot-Watt University, Edinburgh EH14 4AS, United Kingdom;
| | - Eric J Smoll
- Department of Chemistry and Biochemistry, Montana State University, Bozeman, Montana 59717;
| | - Timothy K Minton
- Department of Chemistry and Biochemistry, Montana State University, Bozeman, Montana 59717;
| | - Kenneth G McKendrick
- Institute of Chemical Sciences, School of Engineering and Physical Sciences, Heriot-Watt University, Edinburgh EH14 4AS, United Kingdom;
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34
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Neves CMSS, Held C, Mohammad S, Schleinitz M, Coutinhoa JAP, Freire MG. Effect of salts on the solubility of ionic liquids in water: experimental and electrolyte Perturbed-Chain Statistical Associating Fluid Theory. Phys Chem Chem Phys 2015; 17:32044-32052. [PMID: 26575280 PMCID: PMC5033075 DOI: 10.1039/c5cp06166k] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/04/2022]
Abstract
Due to scarce available experimental data, as well as due to the absence of predictive models, the influence of salts on the solubility of ionic liquids (ILs) in water is still poorly understood. To this end, this work addresses the solubility of the IL 1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ([C4C1im][NTf2]), at 298.15 K and 0.1 MPa, in aqueous salt solutions (from 0.1 to 1.5 mol kg(-1)). At salt molalities higher than 0.2 mol kg(-1), all salts caused salting-out of [C4C1im][NTf2] from aqueous solution with their strength decreasing in the following order: Al2(SO4)3 > ZnSO4 > K3C6H5O7 > KNaC4H4O6 > K3PO4 > Mg(CH3CO2)2 > K2HPO4 > MgSO4 > KH2PO4 > KCH3CO2. Some of these salts lead however to the salting-in of [C4C1im][NTf2] in aqueous medium at salt molalities lower than 0.2 mol kg(-1). To attempt the development of a model able to describe the salt effects, comprising both the salting-in and salting-out phenomena observed, the electrolyte Perturbed-Chain Statistical Associating Fluid Theory (ePC-SAFT) was applied using ion-specific parameters. The gathered experimental data was modelled using ePC-SAFT parameters complemented by fitting a single binary parameter between K(+) and the IL-ions to the IL solubility in K3PO4 aqueous solutions. Based on this approach, the description of anion-specific salting-out effects of the remaining potassium salts was found to be in good agreement with experimental data. Remarkably, ePC-SAFT is even able to predict the salting-in effect induced by K2HPO4, based on the single K(+)/IL-ions binary parameter which was fitted to an exclusively salting-out effect promoted by K3PO4. Finally, ePC-SAFT was applied to predict the influence of other sodium salts on the [C4C1im][NTf2] solubility in water, with experimental data taken from literature, leading to an excellent description of the liquid-liquid phase behaviour.
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Affiliation(s)
- Catarina M. S. S. Neves
- CICECO – Aveiro Institute of Materials, Chemistry Department, University of Aveiro, 3810-193 Aveiro, Portugal
| | - Christoph Held
- Laboratory of Thermodynamics, Department of Biochemical and Chemical Engineering, Technische Universitaet Dortmund, Emil-Figge-Str. 70, 44227 Dortmund, Germany
| | - Sultan Mohammad
- Laboratory of Thermodynamics, Department of Biochemical and Chemical Engineering, Technische Universitaet Dortmund, Emil-Figge-Str. 70, 44227 Dortmund, Germany
| | - Miko Schleinitz
- Laboratory of Thermodynamics, Department of Biochemical and Chemical Engineering, Technische Universitaet Dortmund, Emil-Figge-Str. 70, 44227 Dortmund, Germany
| | - João A. P. Coutinhoa
- CICECO – Aveiro Institute of Materials, Chemistry Department, University of Aveiro, 3810-193 Aveiro, Portugal
| | - Mara G. Freire
- CICECO – Aveiro Institute of Materials, Chemistry Department, University of Aveiro, 3810-193 Aveiro, Portugal
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Affiliation(s)
- Robert Hayes
- Discipline
of Chemistry, The University of Newcastle, NSW 2308, Callaghan, Australia
| | - Gregory G. Warr
- School
of Chemistry, The University of Sydney, NSW 2006, Sydney, Australia
| | - Rob Atkin
- Discipline
of Chemistry, The University of Newcastle, NSW 2308, Callaghan, Australia
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Rezabal E, Schäfer T. Ionic liquids as solvents of polar and non-polar solutes: affinity and coordination. Phys Chem Chem Phys 2015; 17:14588-97. [DOI: 10.1039/c5cp01774b] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Evolution of H2O and CO2 interactions with an ionic liquid (IL) from gas phase to IL phase is described. Affinity is lost and coordination patterns vary in the process, favouring H2O–anion and CO2–cation interactions.
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Affiliation(s)
- Elixabete Rezabal
- Laboratoire de Chimie Moleculaire
- Department of Chemistry
- Ecole Polytechnique and CNRS
- 91128 Palaiseau Cedex
- France
| | - Thomas Schäfer
- POLYMAT
- University of the Basque Country UPV/EHU 20018 Donostia-San Sebastián
- Spain
- Ikerbasque
- Basque Foundation for Science
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38
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Villar-Garcia IJ, Fearn S, Ismail NL, McIntosh AJS, Lovelock KRJ. Fine tuning the ionic liquid–vacuum outer atomic surface using ion mixtures. Chem Commun (Camb) 2015; 51:5367-70. [PMID: 25236677 DOI: 10.1039/c4cc06307d] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Ionic liquid–vacuum outer atomic surfaces can be created that are remarkably different from the bulk composition.
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Affiliation(s)
| | - Sarah Fearn
- Department of Materials
- Imperial College
- London
- UK
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39
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Men S, Lovelock KRJ, Licence P. Directly probing the effect of the solvent on a catalyst electronic environment using X-ray photoelectron spectroscopy. RSC Adv 2015. [DOI: 10.1039/c5ra04662a] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
The anion of an ionic liquid can significantly influence the electronic environment of a metal centre, and thus impact upon reaction performance in a model Suzuki cross coupling reaction.
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Affiliation(s)
- Shuang Men
- Shenyang Ligong University
- School of Material Science and Engineering
- Shenyang
- China
- The University of Nottingham
| | | | - Peter Licence
- The University of Nottingham
- School of Chemistry
- Nottingham
- United Kingdom
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40
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Regeta K, Bannwarth C, Grimme S, Allan M. Free electrons and ionic liquids: study of excited states by means of electron-energy loss spectroscopy and the density functional theory multireference configuration interaction method. Phys Chem Chem Phys 2015; 17:15771-80. [DOI: 10.1039/c5cp01417d] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Collisions of slow electrons with ionic liquids and DFT/MRCI calculations reveal triplet states and interesting physics at low energies.
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Affiliation(s)
- Khrystyna Regeta
- Department of Chemistry
- University of Fribourg
- Fribourg
- Switzerland
| | - Christoph Bannwarth
- Mulliken Center for Theoretical Chemistry
- Institut für Physikalische und Theoretische Chemie
- Universität Bonn
- 53115 Bonn
- Germany
| | - Stefan Grimme
- Mulliken Center for Theoretical Chemistry
- Institut für Physikalische und Theoretische Chemie
- Universität Bonn
- 53115 Bonn
- Germany
| | - Michael Allan
- Department of Chemistry
- University of Fribourg
- Fribourg
- Switzerland
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41
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dos Santos DJ, Cordeiro MND. Effect of replacing [NTf2] by [PF6] anion on the [BMIm][NTf2] ionic liquid confined by gold. MOLECULAR SIMULATION 2014. [DOI: 10.1080/08927022.2014.986122] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
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Duarte D, Salanne M, Rotenberg B, Bizeto MA, Siqueira LJA. Structure of tetraalkylammonium ionic liquids in the interlayer of modified montmorillonite. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2014; 26:284107. [PMID: 24920411 DOI: 10.1088/0953-8984/26/28/284107] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
We perform molecular dynamics simulations of tetraalkylammonium ionic liquids confined in the interlayer of montmorillonite (MMT). We study the structure and energetics of the systems, which consist of cations with two different alkyl chain lengths and several ionic liquid concentrations. The results we obtained for the structure, namely the presence of a strong layering in all systems and the formation of nonpolar domains with interdigitated alkyl chains in some cases, are largely consistent with previous surface force balance experiments performed on similar systems. Finally, we show that swelling of the organo-modified MMT by a large amount of ionic liquid seems energetically favorable in all cases.
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Affiliation(s)
- Daniel Duarte
- Laboratório de Materiais Híbridos, Departamento de Ciências Exatas e da Terra, Instituto de Ciências Ambientais, Químicas e Farmacêuticas, Universidade Federal de São Paulo, CEP 09913-030, Diadema, SP, Brazil
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Malberg F, Brehm M, Hollóczki O, Pensado AS, Kirchner B. Understanding the evaporation of ionic liquids using the example of 1-ethyl-3-methylimidazolium ethylsulfate. Phys Chem Chem Phys 2014; 15:18424-36. [PMID: 24037209 DOI: 10.1039/c3cp52966e] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
In this work we present a comprehensive temperature-dependence analysis of both the structural and the dynamic properties of a vaporized ionic liquid (1-ethyl-3-methylimidazolium ethylsulfate). This particular ionic liquid is known to be distillable from experimental studies and thus enables us to deepen the understanding of the evaporation mechanism of ionic liquids. We have used ab initio molecular dynamics of one ion pair at three different temperatures to accurately describe the interactions present in this model ionic liquid. By means of radial and spatial distribution functions a large impact on the coordination pattern at 400 K is shown which could explain the transfer of one ion pair from the bulk to the gas phase. Comparison of the free energy surfaces at 300 K and 600 K supports the idea of bulk phase-like and gas phase-like ion pairs. The different coordination patterns caused by the temperature, describing a loosening of the anion side chains, are also well reflected in the power spectra. The lifetime analysis of typical conformations for ionic liquids shows a characteristic behavior at 400 K (temperature close to the experimental evaporation temperature), indicating that conformational changes occur when the ionic liquid is evaporated.
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Affiliation(s)
- Friedrich Malberg
- Mulliken Center for Theoretical Chemistry, Institut für Physikalische und Theoretische Chemie, Universität Bonn, Beringstr. 4+6, D-53115 Bonn, Germany.
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Kolbeck C, Niedermaier I, Deyko A, Lovelock KRJ, Taccardi N, Wei W, Wasserscheid P, Maier F, Steinrück HP. Influence of Substituents and Functional Groups on the Surface Composition of Ionic Liquids. Chemistry 2014; 20:3954-65. [DOI: 10.1002/chem.201304549] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2013] [Indexed: 11/10/2022]
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46
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Paredes X, Fernández J, Pádua AAH, Malfreyt P, Malberg F, Kirchner B, Pensado AS. Bulk and Liquid–Vapor Interface of Pyrrolidinium-Based Ionic Liquids: A Molecular Simulation Study. J Phys Chem B 2014; 118:731-42. [DOI: 10.1021/jp406651f] [Citation(s) in RCA: 45] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Xavier Paredes
- Laboratorio de
Propiedades Termofı́sicas, Departamento de
Fı́sica Aplicada, Universidade de Santiago de Compostela, E-15782 Santiago de Compostela, Spain
| | - Josefa Fernández
- Laboratorio de
Propiedades Termofı́sicas, Departamento de
Fı́sica Aplicada, Universidade de Santiago de Compostela, E-15782 Santiago de Compostela, Spain
| | - Agílio A. H. Pádua
- Institut de Chimie
de Clermont-Ferrand, Equipe Thermodynamique et Interactions Moléculaires, Clermont Université, Université Blaise Pascal, BP 80026, 63171 Aubiere, France
- CNRS, UMR6296 ICCF, BP 80026, F-63171 Aubière, France
| | - Patrice Malfreyt
- Institut de Chimie
de Clermont-Ferrand, Equipe Thermodynamique et Interactions Moléculaires, Clermont Université, Université Blaise Pascal, BP 80026, 63171 Aubiere, France
- CNRS, UMR6296 ICCF, BP 80026, F-63171 Aubière, France
| | - Friedrich Malberg
- Mulliken Center
for Theoretical Chemistry, Institut für Physikalische und Theoretische
Chemie, Universität Bonn, Beringstrasse 4+6, D-53115 Bonn, Germany
| | - Barbara Kirchner
- Mulliken Center
for Theoretical Chemistry, Institut für Physikalische und Theoretische
Chemie, Universität Bonn, Beringstrasse 4+6, D-53115 Bonn, Germany
| | - Alfonso S. Pensado
- Laboratorio de
Propiedades Termofı́sicas, Departamento de
Fı́sica Aplicada, Universidade de Santiago de Compostela, E-15782 Santiago de Compostela, Spain
- Mulliken Center
for Theoretical Chemistry, Institut für Physikalische und Theoretische
Chemie, Universität Bonn, Beringstrasse 4+6, D-53115 Bonn, Germany
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47
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Villar-Garcia IJ, Fearn S, De Gregorio GF, Ismail NL, Gschwend FJV, McIntosh AJS, Lovelock KRJ. The ionic liquid–vacuum outer atomic surface: a low-energy ion scattering study. Chem Sci 2014. [DOI: 10.1039/c4sc00640b] [Citation(s) in RCA: 40] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
We have identified elements present in the ionic liquid–vacuum outer atomic surface of 23 ionic liquids using high sensitivity low-energy ion scattering (LEIS), a very surface sensitive technique.
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Affiliation(s)
| | - Sarah Fearn
- Department of Materials
- Imperial College London
- , UK
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48
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Kolbeck C, Deyko A, Matsuda T, Kohler FTU, Wasserscheid P, Maier F, Steinrück HP. Temperature-Dependent Surface-Enrichment Effects of Imidazolium-Based Ionic Liquids. Chemphyschem 2013; 14:3726-30. [DOI: 10.1002/cphc.201300719] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2013] [Indexed: 11/09/2022]
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49
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Lísal M, Izák P. Molecular dynamics simulations of n-hexane at 1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl) imide interface. J Chem Phys 2013; 139:014704. [DOI: 10.1063/1.4811673] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
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50
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Niedermeyer H, Hallett JP, Villar-Garcia IJ, Hunt PA, Welton T. Mixtures of ionic liquids. Chem Soc Rev 2013; 41:7780-802. [PMID: 22890419 DOI: 10.1039/c2cs35177c] [Citation(s) in RCA: 348] [Impact Index Per Article: 31.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
Simple ionic liquids have long been held to be designer solvents, based upon the ability to independently vary their cations and anions. The formation of mixtures of ionic liquids increases this synthetic flexibility. We review the available literature of these ionic liquid mixtures to identify how their properties change and the possibility for their application.
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