1
|
Gousseva E, Towers Tompkins FK, Seymour JM, Parker LG, Clarke CJ, Palgrave RG, Bennett RA, Grau-Crespo R, Lovelock KRJ. Anion-Dependent Strength Scale of Interactions in Ionic Liquids from X-ray Photoelectron Spectroscopy, Ab Initio Molecular Dynamics, and Density Functional Theory. J Phys Chem B 2024; 128:5030-5043. [PMID: 38727250 PMCID: PMC11129296 DOI: 10.1021/acs.jpcb.4c00362] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2024] [Revised: 04/22/2024] [Accepted: 04/22/2024] [Indexed: 05/24/2024]
Abstract
Using a combination of experiments and calculations, we have gained new insights into the nature of anion-cation interactions in ionic liquids (ILs). An X-ray photoelectron spectroscopy (XPS)-derived anion-dependent electrostatic interaction strength scale, determined using XPS core-level binding energies for IL cations, is presented here for 39 different anions, with at least 18 new anions included. Linear correlations of experimental XPS core-level binding energies for IL cations with (a) calculated core binding energies (ab initio molecular dynamics (AIMD) simulations were used to generate high-quality model IL structures followed by single-point density functional theory (DFT) to obtain calculated core binding energies), (b) experimental XPS core-level binding energies for IL anions, and (c) other anion-dependent interaction strength scales led to three main conclusions. First, the effect of different anions on the cation can be related to ground-state interactions. Second, the variations of anion-dependent interactions with the identity of the anion are best rationalized in terms of electrostatic interactions and not occupied valence state/unoccupied valence state interactions or polarizability-driven interactions. Therefore, the XPS-derived anion-dependent interaction strength scale can be explained using a simple electrostatic model based on electrostatic site potentials. Third, anion-probe interactions, irrespective of the identity of the probe, are primarily electrostatic, meaning that our electrostatic interaction strength scale captures some inherent, intrinsic property of anions independent of the probe used to measure the interaction strength scale.
Collapse
Affiliation(s)
| | | | - Jake M. Seymour
- Department
of Chemistry, University of Reading, Reading RG6 6DX, U.K.
| | - Lewis G. Parker
- Department
of Chemistry, University of Reading, Reading RG6 6DX, U.K.
| | - Coby J. Clarke
- School
of Chemistry, University of Nottingham, Nottingham NG7 2RD, U.K.
| | - Robert G. Palgrave
- Department
of Chemistry, University College London, London WC1H 0AJ, U.K.
| | - Roger A. Bennett
- Department
of Chemistry, University of Reading, Reading RG6 6DX, U.K.
| | | | | |
Collapse
|
2
|
Hemmeter D, Merlinsky LS, Baraldo LM, Maier F, Williams FJ, Steinrück HP. Exploring the interfacial behavior of ruthenium complexes in ionic liquids: implications for supported ionic liquid phase catalysts. Phys Chem Chem Phys 2024; 26:7602-7610. [PMID: 38363127 DOI: 10.1039/d4cp00247d] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/17/2024]
Abstract
The interaction of metal complexes with ionic liquids, with a particular focus on the stability and surface concentration of the metal centers, is crucial in applications involving catalysts based on supported ionic liquids. In this study, we synthesized the complexes [Ru(tpy)(bpy)Cl][PF6] and [Ru(tpy)(dcb)Cl][PF6] (tpy = 2,2',2''-terpyridine, bpy = 2,2'-bipyridine, dcb = 4,4'-dicarboxy-2,2'-bipyridine) and we prepared solutions using the ionic liquids (ILs) 1-ethyl-3-methylimidazolium acetate [C2C1Im][OAc] and 1-butyl-3-methylimidazolium hexafluorophosphate [C4C1Im][PF6]. The chemical environment of the Ru(II) metal center and the interfacial behavior of the complexes in the different IL solutions were determined using angle-resolved X-ray photoelectron spectroscopy (ARXPS). In [C4C1Im][PF6], [Ru(tpy)(bpy)Cl][PF6] maintains its chemical structure, while in [C2C1Im][OAc], partial changes in the chemical environment of the Ru center are indicated by XPS, likely due to ligand exchange. The presence of carboxylic acid functional groups in the bipyridyl ligand seems to inhibit this ligand exchange. The investigated complexes do not exhibit surface activity but are depleted from the IL/gas interface. These findings hold significance for the design of new supported ionic liquid phase catalysts based on Ru complexes.
Collapse
Affiliation(s)
- Daniel Hemmeter
- Lehrstuhl für Physikalische Chemie II, Universität Erlangen-Nürnberg, Egerlandstraße 3, Erlangen, Germany.
| | - 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
| | - Luis M Baraldo
- Departamento de Química Inorgánica, Analítica y Química Física, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Buenos Aires, Argentina.
| | - Florian Maier
- Lehrstuhl für Physikalische Chemie II, 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
| | - Hans-Peter Steinrück
- Lehrstuhl für Physikalische Chemie II, Universität Erlangen-Nürnberg, Egerlandstraße 3, Erlangen, Germany.
| |
Collapse
|
3
|
Gousseva E, Midgley SD, Seymour JM, Seidel R, Grau-Crespo R, Lovelock KRJ. Understanding X-ray Photoelectron Spectra of Ionic Liquids: Experiments and Simulations of 1-Butyl-3-methylimidazolium Thiocyanate. J Phys Chem B 2022; 126:10500-10509. [PMID: 36455069 PMCID: PMC9761679 DOI: 10.1021/acs.jpcb.2c06372] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/03/2022]
Abstract
We demonstrate a combined experimental and computational approach to probe the electronic structure and atomic environment of an ionic liquid, based on core level binding energies. The 1-butyl-3-methylimidazolium thiocyanate [C4C1Im][SCN] ionic liquid was studied using ab initio molecular dynamics, and results were compared against previously published and new experimental X-ray photoelectron spectroscopy (XPS) data. The long-held assumption that initial-state effects in XPS dominate the measured binding energies is proven correct, which validates the established premise that the ground state electronic structure of the ionic liquid can be inferred directly from XPS measurements. A regression model based upon site electrostatic potentials and intramolecular bond lengths is shown to account accurately for variations in core-level binding energies within the ionic liquid, demonstrating the important effect of long-range interactions on the core levels and throwing into question the validity of traditional single ion pair ionic liquid calculations for interpreting XPS data.
Collapse
Affiliation(s)
| | - Scott D. Midgley
- Department
of Chemistry, University of Reading, ReadingRG6 6DX, U.K.
| | - Jake M. Seymour
- Department
of Chemistry, University of Reading, ReadingRG6 6DX, U.K.
| | - Robert Seidel
- Helmholtz-Zentrum
Berlin für Materialien und Energie (HZB), Berlin14109, Germany
| | | | | |
Collapse
|
4
|
Shuang Men, Rong J, Zhang T, Wang X, Feng L, Liu C, Jin Y. Spectroscopic Analysis of 1-Butyl-3-methylimidazolium Ionic Liquids: Selection of the Charge Reference and the Electronic Environment. RUSSIAN JOURNAL OF PHYSICAL CHEMISTRY A 2018. [DOI: 10.1134/s0036024418100308] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
|
5
|
Men S, Liu Y, Jin Y. Probing the Cellulose-Ionic Liquids Interaction by X-ray Photoelectron Spectroscopy. POLYMER SCIENCE SERIES A 2018. [DOI: 10.1134/s0965545x18030124] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
|
6
|
Men S, Licence P. Probing the electronic environment of binary and ternary ionic liquid mixtures by X-ray photoelectron spectroscopy. Chem Phys Lett 2017. [DOI: 10.1016/j.cplett.2017.08.034] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
|
7
|
|
8
|
X-ray photoelectron spectroscopy of trihalide ionic liquids: Comparison to halide-based analogues, anion basicity and beam damage. Chem Phys Lett 2017. [DOI: 10.1016/j.cplett.2017.05.010] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
|
9
|
Men S, Jiang J. Probing the impact of the cation acidity on the cation-anion interaction in ionic liquids by X-ray photoelectron spectroscopy. Chem Phys Lett 2017. [DOI: 10.1016/j.cplett.2017.03.081] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
|
10
|
Men S, Jiang J, Licence P. Spectroscopic analysis of 1-butyl-2,3-dimethylimidazolium ionic liquids: Cation-anion interactions. Chem Phys Lett 2017. [DOI: 10.1016/j.cplett.2017.02.050] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
|