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Rauber D, Philippi F, Becker J, Zapp J, Morgenstern B, Kuttich B, Kraus T, Hempelmann R, Hunt P, Welton T, Kay CWM. Anion and ether group influence in protic guanidinium ionic liquids. Phys Chem Chem Phys 2023; 25:6436-6453. [PMID: 36779955 DOI: 10.1039/d2cp05724g] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Ionic liquids are attractive liquid materials for many advanced applications. For targeted design, in-depth knowledge about their structure-property-relations is urgently needed. We prepared a set of novel protic ionic liquids (PILs) with a guanidinium cation with either an ether or alkyl side chain and different anions. While being a promising cation class, the available data is insufficient to guide design. We measured thermal and transport properties, nuclear magnetic resonance (NMR) spectra as well as liquid and crystalline structures supported by ab initio computations and were able to obtain a detailed insight into the influence of the anion and the ether substitution on the physical and spectroscopic properties. For the PILs, hydrogen bonding is the main interaction between cation and anion and the H-bond strength is inversely related to the proton affinity of the constituting acid and correlated to the increase of 1H and 15N chemical shifts. Using anions from acids with lower proton affinity leads to proton localization on the cation as evident from NMR spectra and self-diffusion coefficients. In contrast, proton exchange was evident in ionic liquids with triflate and trifluoroacetate anions. Using imide-type anions and ether side groups decreases glass transitions as well as fragility, and accelerated dynamics significantly. In case of the ether guanidinium ionic liquids, the conformation of the side chain adopts a curled structure as the result of dispersion interactions, while the alkyl chains prefer a linear arrangement.
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Affiliation(s)
- Daniel Rauber
- Department of Chemistry, Saarland University, Campus B 2.2, 66123 Saarbrücken, Germany.
| | - Frederik Philippi
- Department of Chemistry, Molecular Sciences Research Hub, Imperial College London, White City Campus, London W12 0BZ, UK
| | - Julian Becker
- Department of Chemistry, Molecular Sciences Research Hub, Imperial College London, White City Campus, London W12 0BZ, UK
| | - Josef Zapp
- Pharmaceutical Biology, Saarland University, Campus B 2.3, 66123 Saarbrücken, Germany
| | - Bernd Morgenstern
- Department of Chemistry, Saarland University, Campus B 2.2, 66123 Saarbrücken, Germany.
| | - Björn Kuttich
- INM-Leibniz Institute for New Materials, Campus D2.2, 66123 Saarbrücken, Germany
| | - Tobias Kraus
- Department of Chemistry, Saarland University, Campus B 2.2, 66123 Saarbrücken, Germany. .,INM-Leibniz Institute for New Materials, Campus D2.2, 66123 Saarbrücken, Germany
| | - Rolf Hempelmann
- Department of Chemistry, Saarland University, Campus B 2.2, 66123 Saarbrücken, Germany.
| | - Patricia Hunt
- Department of Chemistry, Molecular Sciences Research Hub, Imperial College London, White City Campus, London W12 0BZ, UK.,School of Chemical and Physical Sciences, Victoria University of Wellington, New Zealand
| | - Tom Welton
- Department of Chemistry, Molecular Sciences Research Hub, Imperial College London, White City Campus, London W12 0BZ, UK
| | - Christopher W M Kay
- Department of Chemistry, Saarland University, Campus B 2.2, 66123 Saarbrücken, Germany. .,London Centre for Nanotechnology, University College London, 17-19 Gordon Street, London WC1H 0AH, UK.
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Malik A, Dhattarwal HS, Kashyap HK. An Overview of Structure and Dynamics Associated with Hydrophobic Deep Eutectic Solvents and Their Applications in Extraction Processes. Chemphyschem 2022; 23:e202200239. [PMID: 35702808 DOI: 10.1002/cphc.202200239] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2022] [Revised: 06/10/2022] [Indexed: 11/10/2022]
Abstract
Recent development of novel water-immiscible green solvents known as hydrophobic deep eutectic solvents (HDESs) has opened the gates for applications requiring media where presence of water is undesirable. Ever since they were prepared, researchers have used HDESs in diverse fields such as extraction processes, CO 2 sequestration, membrane formation, and catalysis. The microstructure and dynamics associated with the species comprising HDESs guide their suitability for specific applications. For example, varying the alkyl tail length of HDES components significantly affects the dynamics of the components and thus helps in tuning the efficiency of extraction processes. The development of HDESs is still in infancy and very few theoretical studies are available in the literature that help in understanding the structure and dynamics of HDESs. This review highlights the recent work focused on the microscopic structure and dynamics of HDESs and their potential applications, particularly in extraction processes. We have also provided a glimpse of how the integration of experiments and computational techniques can help understand the mechanism of extraction processes.
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Affiliation(s)
- Akshay Malik
- Indian Institute of Technology Delhi, Chemistry, Hauz Khas, 110016, New Delhi, INDIA
| | - Harender S Dhattarwal
- IIT Delhi: Indian Institute of Technology Delhi, Chemistry, Hauz Khas, 110016, New Delhi, INDIA
| | - Hemant Kumar Kashyap
- Indian Institute of Technology Delhi, Department of Chemistry, Department of Chemistry, Indian Institute of Technology Delhi, Hauz Khas, 110016, New Delhi, INDIA
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Li Z, Morales-Collazo O, Chrostowski R, Brennecke JF, Mangolini F. In situ nanoscale evaluation of pressure-induced changes in structural morphology of phosphonium phosphate ionic liquid at single-asperity contacts. RSC Adv 2021; 12:413-419. [PMID: 35424509 PMCID: PMC8978665 DOI: 10.1039/d1ra08026a] [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: 11/01/2021] [Accepted: 12/13/2021] [Indexed: 11/21/2022] Open
Abstract
In this work, we perform atomic force microscopy (AFM) experiments to evaluate in situ the dependence of the structural morphology of trihexyltetradecylphosphonium bis(2-ethylhexyl) phosphate ([P6,6,6,14][DEHP]) ionic liquid (IL) on applied pressure. The experimental results obtained upon sliding a diamond-like-carbon-coated silicon AFM tip on mechanically polished steel at an applied pressure up to 5.5 ± 0.3 GPa indicate a structural transition of confined [P6,6,6,14][DEHP] molecules. This pressure-induced morphological change of [P6,6,6,14][DEHP] IL leads to the generation of a lubricious, solid-like interfacial layer, whose growth rate increases with applied pressure and temperature. The structural variation of [P6,6,6,14][DEHP] IL is proposed to derive from the well-ordered layering of the polar groups of ions separated by the apolar tails. These results not only shed new light on the structural organization of phosphonium-based ILs under elevated pressure, but also provide novel insights into the normal pressure-dependent lubrication mechanisms of ILs in general.
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Affiliation(s)
- Zixuan Li
- Texas Materials Institute, The University of Texas at Austin Austin TX 78712 USA .,Materials Science and Engineering Program, The University of Texas at Austin Austin TX 78712 USA
| | - Oscar Morales-Collazo
- McKetta Department of Chemical Engineering, The University of Texas at Austin Austin TX 78712 USA
| | - Robert Chrostowski
- Texas Materials Institute, The University of Texas at Austin Austin TX 78712 USA .,Materials Science and Engineering Program, The University of Texas at Austin Austin TX 78712 USA
| | - Joan F Brennecke
- McKetta Department of Chemical Engineering, The University of Texas at Austin Austin TX 78712 USA
| | - Filippo Mangolini
- Texas Materials Institute, The University of Texas at Austin Austin TX 78712 USA .,Walker Department of Mechanical Engineering, The University of Texas at Austin Austin TX 78712 USA
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Crystallization of mixtures of hydrophilic ionic liquids and water: Evidence of microscopic inhomogeneities. J Colloid Interface Sci 2019; 552:43-50. [PMID: 31100689 DOI: 10.1016/j.jcis.2019.05.034] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2019] [Revised: 05/08/2019] [Accepted: 05/09/2019] [Indexed: 10/26/2022]
Abstract
HYPOTHESIS We compare the effects of water, either intentionally added or due to absorption from the air, on the phase diagram of the hydrophilic 1-butyl-3-methylimidazolium dicyanamide ionic liquid, extending previous investigations to lower temperatures (down to 140 K), with a special attention to the changes of the environment of water molecules and the interface between water and ionic liquid as a function of temperature. EXPERIMENTS Combined infrared spectroscopy and ab-initio calculations provide information about the phase transitions and the intermolecular changes occurring in the liquid. FINDINGS The temperature dependence of the mid-infrared spectrum in the temperature range between 140 and 330 K indicates that in both cases the liquid undergoes a glass transition, but, when the water content is only due to absorption from air, a cold crystallization takes place on heating between ≈240 and ≈265 K, while it is suppressed when water is intentionally added in a greater amount. The analysis of the OH stretching bands indicates the existence of two different "liquid like" water environments. When cold crystallization takes places the water molecules, which seem less coordinated to the other H2O molecules and more related to the anions, appear to be part of the crystallized sample. In both cases, it seems that at microscopic level the sample is not homogeneous, but more likely it is composed of separated clusters or regions of bulk water confined in the ionic liquid.
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Dhabal D, Gupta A, Kashyap HK. Structural investigation of room-temperature ionic liquids and high-temperature ionic melts using triplet correlation functions. J Chem Phys 2017. [DOI: 10.1063/1.4976305] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Affiliation(s)
- Debdas Dhabal
- Department of Chemistry, Indian Institute of Technology Delhi, Hauz Khas, New Delhi 110016, India
| | - Aditya Gupta
- Department of Chemistry, Indian Institute of Technology Delhi, Hauz Khas, New Delhi 110016, India
| | - Hemant K. Kashyap
- Department of Chemistry, Indian Institute of Technology Delhi, Hauz Khas, New Delhi 110016, India
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Price DL, Borodin O, González MA, Kofu M, Shibata K, Yamada T, Yamamuro O, Saboungi ML. Relaxation in a Prototype Ionic Liquid: Influence of Water on the Dynamics. J Phys Chem Lett 2017; 8:715-719. [PMID: 28103664 DOI: 10.1021/acs.jpclett.6b02871] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
The influence of water on the relaxation of a prototype ionic liquid (IL) C8mimBF4 is examined in the IL-rich regime combining quasi-elastic neutron scattering (QENS) and molecular dynamics (MD) simulations. The QENS and MD simulations results for relaxation of IL and the equimolar mixture with water probed by the dynamics of the C8mim hydrogen atoms in the time range of 2 ps to 1 ns are in excellent agreement. The QENS data show that translational relaxation increases by a factor of 7 on the addition of water, while rotational relaxation involving multiple processes fitted by a KWW function with low β values is speeded up by a factor of 3 on the time scale of QENS measurements. The MD simulations show that the cation diffusion coefficient, inverse viscosity, and ionic conductivity increase on the addition of water, consistent with the very small change in ionicity. The difficulties in obtaining rotational and translational diffusion coefficients from fits to QENS experiments of pure ILs and IL-water mixtures are discussed.
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Affiliation(s)
- David L Price
- CNRS, UPR 3079 and Université d'Orléans, Conditions Extrêmes et Matériaux: Haute Température et Irradiation, 1d avenue de la recherche scientifique, 45071 Orléans Cedex 2, France
| | - Oleg Borodin
- Electrochemistry Branch, Sensor and Electron Devices Directorate, U.S. Army Research Laboratory , Adelphi, Maryland 20783, United States
| | - Miguel A González
- Institut Laue Langevin , 71 avenue des Martyrs, 38042 Grenoble Cedex 9, France
| | - Maiko Kofu
- Institute for Solid State Physics, University of Tokyo , 5-1-5 Kashiwanoha, Kashiwa, Chiba 277-8581, Japan
| | - Kaoru Shibata
- Materials and Life Science Division, J-PARC Center, JAEA , Tokai, Ibaraki 319-1195, Japan
| | - Takeshi Yamada
- Neutron R&D Division, CROSS-Tokai , Tokai, Ibaraki 319-1106, Japan
| | - Osamu Yamamuro
- Institute for Solid State Physics, University of Tokyo , 5-1-5 Kashiwanoha, Kashiwa, Chiba 277-8581, Japan
| | - Marie-Louise Saboungi
- IMPMC-Université Pierre et Marie Curie and CNRS , 4 Place Jussieu, F-75252 Paris, France
- Institute of Functional Nano & Soft Materials (FUNSOM), Soochow University , Suzhou, Jiangsu 215123, China
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Sharma S, Gupta A, Dhabal D, Kashyap HK. Pressure-dependent morphology of trihexyl(tetradecyl)phosphonium ionic liquids: A molecular dynamics study. J Chem Phys 2016; 145:134506. [DOI: 10.1063/1.4963271] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Affiliation(s)
- Shobha Sharma
- Department of Chemistry, Indian Institute of Technology Delhi, Hauz Khas, New Delhi 110016, India
| | - Aditya Gupta
- Department of Chemistry, Indian Institute of Technology Delhi, Hauz Khas, New Delhi 110016, India
| | - Debdas Dhabal
- Department of Chemistry, Indian Institute of Technology Delhi, Hauz Khas, New Delhi 110016, India
| | - Hemant K. Kashyap
- Department of Chemistry, Indian Institute of Technology Delhi, Hauz Khas, New Delhi 110016, India
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Sharma S, Gupta A, Kashyap HK. How the Structure of Pyrrolidinium Ionic Liquids Is Susceptible to High Pressure. J Phys Chem B 2016; 120:3206-14. [DOI: 10.1021/acs.jpcb.6b01133] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Shobha Sharma
- Department of Chemistry, Indian Institute of Technology Delhi, Hauz Khas, New Delhi 110016, India
| | - Aditya Gupta
- Department of Chemistry, Indian Institute of Technology Delhi, Hauz Khas, New Delhi 110016, India
| | - Hemant K. Kashyap
- Department of Chemistry, Indian Institute of Technology Delhi, Hauz Khas, New Delhi 110016, India
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Araque JC, Hettige JJ, Margulis CJ. Ionic liquids—Conventional solvent mixtures, structurally different but dynamically similar. J Chem Phys 2015; 143:134505. [DOI: 10.1063/1.4932331] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Affiliation(s)
- Juan C. Araque
- Department of Chemistry, University of Iowa, Iowa City, Iowa 52242, USA
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Gupta A, Sharma S, Kashyap HK. Composition dependent structural organization in trihexyl(tetradecyl)phosphonium chloride ionic liquid-methanol mixtures. J Chem Phys 2015; 142:134503. [DOI: 10.1063/1.4916308] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Affiliation(s)
- Aditya Gupta
- Department of Chemistry, Indian Institute of Technology Delhi, Hauz Khas, New Delhi 110016, India
| | - Shobha Sharma
- Department of Chemistry, Indian Institute of Technology Delhi, Hauz Khas, New Delhi 110016, India
| | - Hemant K. Kashyap
- Department of Chemistry, Indian Institute of Technology Delhi, Hauz Khas, New Delhi 110016, India
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Chen Y, Cao Y, Yan C, Zhang Y, Mu T. The dynamic process of atmospheric water sorption in [BMIM][Ac]: quantifying bulk versus surface sorption and utilizing atmospheric water as a structure probe. J Phys Chem B 2014; 118:6896-907. [PMID: 24840011 DOI: 10.1021/jp502995k] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The dynamic process of the atmospheric water absorbed in acetate-based ionic liquid 1-butyl-3-methyl-imidazolium acetate ([BMIM][Ac]) within 360 min could be described with three steps by using two-dimensional correlation infrared (IR) spectroscopy technique. In Step 1 (0-120 min), only bulk sorption via hydrogen bonding interaction occurs. In Step 2 (120-320 min), bulk and surface sorption takes place simultaneously via both hydrogen bonding interaction and van der Waals force. In Step 3, from 320 min to steady state, only surface sorption via van der Waals force occurs. Specifically, Step 2 could be divided into three substeps. Most bulk sorption with little surface sorption takes place in Step 2a (120-180 min), comparative bulk and surface sorption happens in Step 2b (180-260 min), and most surface sorption while little bulk sorption occurs in Step 2c (260-320 min). Interestingly, atmospheric water is found for the first time to be able to be used as a probe to detect the chemical structure of [BMIM][Ac]. Results show that one anion is surrounded by three C4,5H molecules and two anions are surrounded by five C2H molecules via hydrogen bonds, which are very susceptible to moisture water especially for the former one. The remaining five anions form a multimer (equilibrating with one dimer and one trimer) via a strong hydrogen bonding interaction, which is not easily affected by the introduction of atmospheric water. The alkyl of the [BMIM][Ac] cation aggregates to some extent by van der Walls force, which is moderately susceptible to the water attack. Furthermore, the proportion of bulk sorption vs surface sorption is quantified as about 70% and 30% within 320 min, 63% and 37% within 360 min, and 11% and 89% until steady-state, respectively.
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Affiliation(s)
- Yu Chen
- Department of Chemistry, Renmin University of China , Beijing 100872, P. R. China
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