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Schatz GC, Wodtke AM, Yang X. Spiers Memorial Lecture: New directions in molecular scattering. Faraday Discuss 2024; 251:9-62. [PMID: 38764350 DOI: 10.1039/d4fd00015c] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/21/2024]
Abstract
The field of molecular scattering is reviewed as it pertains to gas-gas as well as gas-surface chemical reaction dynamics. We emphasize the importance of collaboration of experiment and theory, from which new directions of research are being pursued on increasingly complex problems. We review both experimental and theoretical advances that provide the modern toolbox available to molecular-scattering studies. We distinguish between two classes of work. The first involves simple systems and uses experiment to validate theory so that from the validated theory, one may learn far more than could ever be measured in the laboratory. The second class involves problems of great complexity that would be difficult or impossible to understand without a partnership of experiment and theory. Key topics covered in this review include crossed-beams reactive scattering and scattering at extremely low energies, where quantum effects dominate. They also include scattering from surfaces, reactive scattering and kinetics at surfaces, and scattering work done at liquid surfaces. The review closes with thoughts on future promising directions of research.
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Affiliation(s)
- George C Schatz
- Dept of Chemistry, Northwestern University, Evanston, Illinois 60208, USA
| | - Alec M Wodtke
- Institute for Physical Chemistry, Georg August University, Goettingen, Germany
- Max Planck Institute for Multidisciplinary Natural Sciences, Goettingen, Germany.
- International Center for the Advanced Studies of Energy Conversion, Georg August University, Goettingen, Germany
| | - Xueming Yang
- Dalian Institute for Chemical Physics, Chinese Academy of Sciences, Dalian, China
- Department of Chemistry, College of Science, Southern University of Science and Technology, Shenzhen, China
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Elstone NS, Shaw EV, Shimizu K, Lai J, Demé B, Lane PD, Costen ML, McKendrick KG, Youngs S, Rogers SE, Canongia Lopes JN, Bruce DW, Slattery JM. Chain-length dependent organisation in mixtures of hydrogenous and fluorous ionic liquids. Faraday Discuss 2024. [PMID: 39091139 DOI: 10.1039/d4fd00047a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 08/04/2024]
Abstract
As part of an ongoing study of the structure and properties of mixtures of ionic liquids in which one component has a hydrocarbon chain and the other a semiperfluorocarbon chain, we now report a study of the mixtures [C8MIM]1-x[C10MIM-F17]x[Tf2N], [C10MIM]1-x[C8MIM-F13]x[Tf2N] and [C10MIM]1-x[C10MIM-F17]x[Tf2N], where [C8MIM][Tf2N] is 1-methyl-3-octylimidazolium bis(trifluoromethylsulfonyl)imide, [C10MIM][Tf2N] is 1-decyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide, [C8MIM-F13][Tf2N] is 1-(1H,1H,2H,2H-perfluorooctyl)-3-methylimidizolium bis(trifluoromethylsulfonyl)imide and [C10MIM-F17][Tf2N] is 1-(1H,1H,2H,2H-perfluorodecyl)-3-methylimidizolium bis(trifluoromethylsulfonyl)imide. The mixtures were investigated using small-angle X-ray (SAXS) and neutron (SANS) scattering complemented by molecular dynamics simulations (with viscosity and surface tension measurements also possible for the mixtures [C10MIM]1-x[C8MIM-F13]x[Tf2N]). Unlike previous studies of [C8MIM]1-x[C8MIM-F13]x[Tf2N], where no strong evidence of alkyl/fluoroalkyl chain segregation or triphilic behaviour was seen (Elstone et al., J. Phys. Chem. B, 2023, 127, 7394-7407), these new mixtures show the formation of small aggregates of varying sizes of each component, even though all were co-miscible across the full range of compositions. Thus, while a clear polar non-polar peak (PNPP) was observed at large or small values of x, at intermediate compositions the small-angle neutron scattering at low q was dominated by scattering from these small aggregates, while at other compositions, there was little or no evidence of the PNPP. The origins of this behaviour are discussed in terms of inter-chain interactions.
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Affiliation(s)
- Naomi S Elstone
- Department of Chemistry, University of York, Heslington, York YO10 5DD, UK.
| | - Emily V Shaw
- Department of Chemistry, University of York, Heslington, York YO10 5DD, UK.
| | - Karina Shimizu
- Centro de Química Estrutural, Institute of Molecular Sciences, Instituto Superior Técnico, Universidade de Lisboa, Av. Rovisco Pais, Lisboa 1049 001, Portugal.
| | - Joshua Lai
- Department of Chemistry, University of York, Heslington, York YO10 5DD, UK.
| | - Bruno Demé
- Institut Laue-Langevin, Grenoble 38000, France
| | - Paul D Lane
- Institute of Chemical Sciences, School of Engineering and Physical Sciences, Heriot-Watt University, Edinburgh EH14 4AS, UK
| | - Matthew L Costen
- Institute of Chemical Sciences, School of Engineering and Physical Sciences, Heriot-Watt University, Edinburgh EH14 4AS, UK
| | - Kenneth G McKendrick
- Institute of Chemical Sciences, School of Engineering and Physical Sciences, Heriot-Watt University, Edinburgh EH14 4AS, UK
| | - Sarah Youngs
- ISIS Neutron and Muon Source, Harwell Campus, Didcot OX11 0QX, UK
| | - Sarah E Rogers
- ISIS Neutron and Muon Source, Harwell Campus, Didcot OX11 0QX, UK
| | - Jose N Canongia Lopes
- Centro de Química Estrutural, Institute of Molecular Sciences, Instituto Superior Técnico, Universidade de Lisboa, Av. Rovisco Pais, Lisboa 1049 001, Portugal.
| | - Duncan W Bruce
- Department of Chemistry, University of York, Heslington, York YO10 5DD, UK.
| | - John M Slattery
- Department of Chemistry, University of York, Heslington, York YO10 5DD, UK.
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Elstone N, Shimizu K, Shaw EV, Lane PD, D’Andrea L, Demé B, Mahmoudi N, Rogers SE, Youngs S, Costen ML, McKendrick KG, Canongia Lopes JN, Bruce DW, Slattery JM. Understanding the Liquid Structure in Mixtures of Ionic Liquids with Semiperfluoroalkyl or Alkyl Chains. J Phys Chem B 2023; 127:7394-7407. [PMID: 37555779 PMCID: PMC10461228 DOI: 10.1021/acs.jpcb.3c02647] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2023] [Revised: 06/15/2023] [Indexed: 08/10/2023]
Abstract
By mixing ionic liquids (ILs), it is possible to fine-tune their bulk and interfacial structure. This alters their physical properties and solvation behavior and is a simple way to prepare a collection of ILs whose properties can be tuned to optimize a specific application. In this study, mixtures of perfluorinated and alkylated ILs have been prepared, and links between composition, properties, and nanostructure have been investigated. These different classes of ILs vary substantially in the flexibility and polarizability of their chains. Thus, a range of useful structural and physical property variations are accessible through mixing that will expand the library of IL mixtures available in an area that to this point has received relatively little attention. In the experiments presented herein, the physical properties and bulk structure of mixtures of 1-methyl-3-octylimidazolium bis(trifluoromethylsulfonyl)imide [C8MIM][Tf2N] and 1-(1H,1H,2H,2H-perfluorooctyl)-3-methylimidazolium bis(trifluoromethylsulfonyl)imide [C8MIM-F13][Tf2N] have been prepared. The bulk liquid structure was investigated using a combination of small-angle X-ray and neutron scattering (SAXS and SANS, respectively) experiments in combination with atomistic molecular dynamics simulations and the measurement of density and viscosity. We observed that the addition of [C8MIM-F13][Tf2N] to [C8MIM][Tf2N] causes changes in the nanostructure of the IL mixtures that are dependent on composition so that variation in the characteristic short-range correlations is observed as a function of composition. Thus, while the length scales associated with the apolar regions (polar non-polar peak─PNPP) increase with the proportion of [C8MIM-F13][Tf2N] in the mixtures, perhaps surprisingly given the greater volume of the fluorocarbon chains, the length scale of the charge-ordering peak decreases. Interestingly, consideration of the contact peak shows that its origins are both in the direct anion···cation contact length scale and the nature (and hence volume) of the chains appended to the imidazolium cation.
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Affiliation(s)
- Naomi
S. Elstone
- Department
of Chemistry, University of York, Heslington, York YO10
5DD, U.K.
| | - Karina Shimizu
- Centro
de Química Estrutural, Institute of Molecular Sciences, Instituto
Superior Técnico, Universidade de
Lisboa, Av. Rovisco Pais, Lisboa 1049 001, Portugal
| | - Emily V. Shaw
- Department
of Chemistry, University of York, Heslington, York YO10
5DD, 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.
| | - Bruno Demé
- Institut
Laue−Langevin, Grenoble 38000, France
| | - Najet Mahmoudi
- ISIS
Neutron Source Facility, Harwell Science and Innovation Campus, Didcot OX11 0DE, U.K.
| | - Sarah E. Rogers
- ISIS
Neutron Source Facility, Harwell Science and Innovation Campus, Didcot OX11 0DE, U.K.
| | - Sarah Youngs
- ISIS
Neutron Source Facility, Harwell Science and Innovation Campus, Didcot OX11 0DE, 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.
| | - Jose N. Canongia Lopes
- Centro
de Química Estrutural, Institute of Molecular Sciences, Instituto
Superior Técnico, Universidade de
Lisboa, Av. Rovisco Pais, Lisboa 1049 001, Portugal
| | - 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.
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Urzúa JI, Valenzuela ML, Cavieres J, Inestrosa-Izurieta MJ. Ionic liquid mixtures as energy storage materials: a preliminary and comparative study based on thermal storage density. RSC Adv 2023; 13:19412-19419. [PMID: 37383686 PMCID: PMC10293934 DOI: 10.1039/d3ra02901h] [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: 05/02/2023] [Accepted: 06/19/2023] [Indexed: 06/30/2023] Open
Abstract
Fifteen equimolar binary mixtures are synthesized and thermophysically evaluated in this study. These mixtures are derived from six ionic liquids (ILs) based on methylimidazolium and 2,3-dimethylimidazolium cations with butyl chains. The objective is to compare and elucidate the impact of small structural changes on the thermal properties. The preliminary results are compared to previously obtained results with mixtures containing longer eight-carbon chains. The study demonstrates that certain mixtures exhibit an increase in their heat capacity. Additionally, due to their higher densities, these mixtures achieve a thermal storage density equivalent to that of mixtures with longer chains. Moreover, their thermal storage density surpasses that of some conventional materials commonly used for energy storage.
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Affiliation(s)
- Julio I Urzúa
- Centro de Materiales para la Transición y Sostenibilidad Energética, Comisión Chilena de Energía Nuclear Ruta 68, km 20, Pudahuel Santiago Chile
| | - María Luisa Valenzuela
- Universidad Autónoma de Chile, Facultad de Ingeniería, Instituto de Ciencias Químicas Aplicadas, Grupo de Investigación en Energía y Procesos Sustentables Av. El Llano Subercaseaux 2801 Santiago Chile
| | - Jenifer Cavieres
- Departamento de Ingeniería Química y Ambiental, Universidad Técnica Federico Santa María Av. Vicuña Mackenna 3939, San Joaquín Santiago Chile
| | - María José Inestrosa-Izurieta
- Centro de Materiales para la Transición y Sostenibilidad Energética, Comisión Chilena de Energía Nuclear Ruta 68, km 20, Pudahuel Santiago Chile
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Hemmeter D, Kremitzl D, Schulz PS, Wasserscheid P, Maier F, Steinrück HP. The Buoy Effect: Surface Enrichment of a Pt Complex in IL Solution by Ligand Design. Chemistry 2023; 29:e202203325. [PMID: 36446030 PMCID: PMC10107114 DOI: 10.1002/chem.202203325] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2022] [Revised: 11/28/2022] [Accepted: 11/29/2022] [Indexed: 11/30/2022]
Abstract
The targeted enrichment of a Pt complex with an ionic liquid (IL)-derived ligand system in IL solution is demonstrated by using angle-resolved X-ray photoelectron spectroscopy. When the ligand system is complemented with fluorinated side chains, the complex accumulates strongly at the IL/gas interface, while in an equivalent solution of a complex without these substituents no such effect could be observed. This buoy-like behavior induces strong population of the complex at the outermost molecular layer close to surface saturation, which was studied over a range from 5 to 30 %mol . The surface enrichment was found to be most efficient at the lowest concentration, which is particularly favorable for catalytic applications such as supported ionic-liquid-phase (SILP) catalysis.
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Affiliation(s)
- Daniel Hemmeter
- Lehrstuhl für Physikalische Chemie 2, Friedrich-Alexander-Universität Erlangen-Nürnberg, Egerlandstr. 3, 91058, Erlangen, Germany
| | - Daniel Kremitzl
- Lehrstuhl für Chemische Reaktionstechnik, Friedrich-Alexander-Universität Erlangen-Nürnberg, Egerlandstr. 3, 91058, Erlangen, Germany
| | - Peter S Schulz
- Lehrstuhl für Chemische Reaktionstechnik, Friedrich-Alexander-Universität Erlangen-Nürnberg, Egerlandstr. 3, 91058, Erlangen, Germany
| | - Peter Wasserscheid
- Lehrstuhl für Chemische Reaktionstechnik, Friedrich-Alexander-Universität Erlangen-Nürnberg, Egerlandstr. 3, 91058, Erlangen, Germany.,Forschungszentrum Jülich GmbH, Helmholtz-Institute Erlangen-Nürnberg for Renewable Energy (IEK-11), Egerlandstr. 3, 91058, Erlangen, Germany
| | - Florian Maier
- Lehrstuhl für Physikalische Chemie 2, Friedrich-Alexander-Universität Erlangen-Nürnberg, Egerlandstr. 3, 91058, Erlangen, Germany
| | - Hans-Peter Steinrück
- Lehrstuhl für Physikalische Chemie 2, Friedrich-Alexander-Universität Erlangen-Nürnberg, Egerlandstr. 3, 91058, Erlangen, Germany
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Direct Correlation of Surface Tension and Surface Composition of Ionic Liquid Mixtures-A Combined Vacuum Pendant Drop and Angle-Resolved X-ray Photoelectron Spectroscopy Study. MOLECULES (BASEL, SWITZERLAND) 2022; 27:molecules27238561. [PMID: 36500653 PMCID: PMC9736233 DOI: 10.3390/molecules27238561] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 11/09/2022] [Revised: 11/29/2022] [Accepted: 12/01/2022] [Indexed: 12/12/2022]
Abstract
We investigated the surface tension and surface composition of various mixtures of the two ionic liquids (ILs) 1-methyl-3-octyl-imidazolium hexafluorophosphate [C8C1Im][PF6] and 1,3-bis(polyethylene glycol)imidazolium iodide [(mPEG2)2Im]I in the temperature range from 230 to 370 K under ultraclean vacuum conditions. The surface tension was measured using a newly developed apparatus, and the surface composition was determined by angle-resolved X-ray photoelectron spectroscopy (ARXPS). In the pure ILs, the alkyl chains of [C8C1Im][PF6] and the PEG chains of [(mPEG2)2Im]I are enriched at the IL/vacuum interface. In the mixtures, a strong selective surface enrichment of the alkyl chains occurs, which is most pronounced at low [C8C1Im][PF6] contents. For the surface tension, strong deviations from an ideal mixing behaviour take place. By applying a simple approach based on the surface composition of the mixtures as deduced from ARXPS, we are able to predict and reproduce the experimentally measured temperature-dependent surface tension values with astonishingly high accuracy.
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Cabry CP, D'Andrea L, Elstone NS, Kirchhecker S, Riccobono A, Khazal I, Li P, Rogers SE, Bruce DW, Slattery JM. Small-angle neutron scattering from mixtures of long- and short-chain 3-alkyl-1-methyl imidazolium bistriflimides. Phys Chem Chem Phys 2022; 24:15811-15823. [PMID: 35762383 DOI: 10.1039/d2cp01528e] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The preparation of mixtures of ionic liquids (ILs) represents an attractive strategy to tune their properties, an important aspect of which is to understand how the structure of the bulk varies with composition. In this study, small-angle neutron scattering (SANS) was used to probe mixtures of methylimidazolium-based ionic liquids [Cnmim][Tf2N] with [C2mim][Tf2N]) (n = 4, 6, 8 and 10) and of [Cmmim][Tf2N] with [C12mim][Tf2N] (m = 2, 4, 6 and 8). Mixtures were prepared in both contrasts, which is to say that one component would be fully hydrogenated while the other was fully deuterated, and vice versa. Data were fitted using a range of appropriate models, of which the Teubner-Strey model provided most useful information and the pure materials showed a nascent Polar Non-polar Peak (PNPP) for n = 6, which became more evident as n increased. In the mixtures [Cnmim]x[C2mim]1-x[Tf2N], the PNPP was evident for n = 10 and 8, nascent for n = 6 and absent for n = 4, with percolation showing a very strong dependence on the chain length of the added IL, [Cnmim][Tf2N]. In contrast, while the ability of [C12mim][Tf2N] to form percolated structures was damped when mixed with [Cmmim][Tf2N], as m increased from 2 to 6, this effect was less strong. However, data obtained for mixtures of [C12mim][Tf2N] and [C8mim][Tf2N], both of which percolate as pure materials, did not fit easily in any of the models applied to the previous systems and gave results that depended on the contrast used. Complementary small-angle X-ray scattering (SAXS) data, however, showed the expected evolution and behaviour of the PNPP, COP and CP, revealing that the unexpected observations were due to an adventitious matching out of isotopic contrasts. As well as revealing details of the structures of these IL mixtures, the results also point to complementary strategies for generating bulk percolated structures as a function of cation chain length.
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Affiliation(s)
| | - Lucía D'Andrea
- Department of Chemistry, University of York, Heslington, York YO10 5DD, UK.
| | - Naomi S Elstone
- Department of Chemistry, University of York, Heslington, York YO10 5DD, UK.
| | - Sarah Kirchhecker
- Department of Chemistry, University of York, Heslington, York YO10 5DD, UK.
| | - Alessio Riccobono
- Department of Chemistry, University of York, Heslington, York YO10 5DD, UK.
| | - Iman Khazal
- Department of Chemistry, University of York, Heslington, York YO10 5DD, UK.
| | - Peixun Li
- ISIS, Science & Technology Facilities Council, Rutherford Appleton Laboratory, Chilton, UK
| | - Sarah E Rogers
- ISIS, Science & Technology Facilities Council, Rutherford Appleton Laboratory, Chilton, UK
| | - Duncan W Bruce
- Department of Chemistry, University of York, Heslington, York YO10 5DD, UK.
| | - John M Slattery
- Department of Chemistry, University of York, Heslington, York YO10 5DD, UK.
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