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Special Issue "Ionic Liquids, from Their Synthesis to Their Applications"

A special issue of Molecules (ISSN 1420-3049). This special issue belongs to the section "Physical Chemistry".

Deadline for manuscript submissions: closed (31 August 2020).

Special Issue Editors

Prof. Dr. Johan Jacquemin
E-Mail Website
Guest Editor
Laboratoire PCM2E, Université de Tours, Parc de Grandmont, 37200 Tours, France
Interests: thermodynamics; structure – properties relation; thermodynamic models for process simulation
Special Issues and Collections in MDPI journals
Prof. Dr. Fouad Ghamouss
E-Mail Website
Guest Editor
Department of Chemistry, University of Tours, 37204 Tours, France
Interests: Li-ion and post-lithium-ion batteries; supercapacitors; electrochemistry; electrolytes
Special Issues and Collections in MDPI journals

Special Issue Information

Dear Colleagues,

The aim of this Special Issue is to provide an original and unique environment for researchers in academia and industry to share and discuss their cutting-edge results on the synthesis and physical and applied chemistry of novel ionic liquids, covering their synthesis, characterization, modelling, and/or applications.

This class of materials possess unique properties that are useful for a wide range of applications in fields as diverse as petrochemicals, energy storage, fine chemicals, pharmaceuticals, biotechnology, hydrometallurgy, environmental remediation, and nuclear sciences. In all these fields, ionic liquids can provide novel research strategy and technologies that enable major contributions towards establishing the sustainable processes required for the future process industry.

Topics: 

  • Application of ionic liquids for the following:
    a. Analytical separations;
    b. Absorption/adsorption;
    c. Crystallization;
    d. Distillation;
    e. Extraction/leaching;
    f. Membrane separations;
    g. Purification;
    h. Novel separation processes;
    i. Energy storage (supercapacitor, metal-ion batteries, etc.).
  • Application of ionic liquids in the following:
    a. Electrochemistry;
    b. Biotechnology and biorefining;
    c. Chemicals, pharmaceuticals, and/or petrochemicals;
    d. Gas capture and utilization;
    e. Environmental remediation;
    f. Polymerization;
    g. Surface cleaning;
    h. Waste treatment.
  • Process modeling and fundamental studies: 
    a. Equations of state;
    b. Molecular modeling and simulation;
    c. Electronic structure calculations;
    d. Process simulation;
    e. Group contribution modeling;
    f. QSPR/QSAR modeling.

Dr. Johan Jacquemin
Dr. Fouad Ghamouss
Guest Editors

Manuscript Submission Information

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. All papers will be peer-reviewed. Accepted papers will be published continuously in the journal (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as short communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Molecules is an international peer-reviewed open access semimonthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 2000 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Keywords

  • Ionic Liquids
  • Physical Chemistry
  • Chemical Chemistry
  • Characterization
  • Chemical Engineering Applications

Published Papers (9 papers)

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Research

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Open AccessArticle
Dissolving Cellulose in 1,2,3-Triazolium- and Imidazolium-Based Ionic Liquids with Aromatic Anions
Molecules 2020, 25(15), 3539; https://doi.org/10.3390/molecules25153539 - 02 Aug 2020
Cited by 3 | Viewed by 1244
Abstract
We present 1,2,3-triazolium- and imidazolium-based ionic liquids (ILs) with aromatic anions as a new class of cellulose solvents. The two anions in our study, benzoate and salicylate, possess a lower basicity when compared to acetate and therefore should lead to a lower amount [...] Read more.
We present 1,2,3-triazolium- and imidazolium-based ionic liquids (ILs) with aromatic anions as a new class of cellulose solvents. The two anions in our study, benzoate and salicylate, possess a lower basicity when compared to acetate and therefore should lead to a lower amount of N-heterocyclic carbenes (NHCs) in the ILs. We characterize their physicochemical properties and find that all of them are liquids at room temperature. By applying force field molecular dynamics (MD) simulations, we investigate the structure and dynamics of the liquids and find strong and long-lived hydrogen bonds, as well as significant ππ stacking between the aromatic anion and cation. Our ILs dissolve up to 8.5 wt.-% cellulose. Via NMR spectroscopy of the solution, we rule out chain degradation or derivatization, even after several weeks at elevated temperature. Based on our MD simulations, we estimate the enthalpy of solvation and derive a simple model for semi-quantitative prediction of cellulose solubility in ILs. With the help of Sankey diagrams, we illustrate the hydrogen bond network topology of the solutions, which is characterized by competing hydrogen bond donors and acceptors. The hydrogen bonds between cellulose and the anions possess average lifetimes in the nanosecond range, which is longer than found in common pure ILs. Full article
(This article belongs to the Special Issue Ionic Liquids, from Their Synthesis to Their Applications)
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Open AccessArticle
Phenylacetonitrile (C6H5CH2CN) Ionic Liquid Blends as Alternative Electrolytes for Safe and High-Performance Supercapacitors
Molecules 2020, 25(11), 2697; https://doi.org/10.3390/molecules25112697 - 10 Jun 2020
Cited by 1 | Viewed by 889
Abstract
The increasing need in the development of storage devices is calling for the formulation of alternative electrolytes, electrochemically stable and safe over a wide range of conditions. To achieve this goal, electrolyte chemistry must be explored to propose alternative solvents and salts to [...] Read more.
The increasing need in the development of storage devices is calling for the formulation of alternative electrolytes, electrochemically stable and safe over a wide range of conditions. To achieve this goal, electrolyte chemistry must be explored to propose alternative solvents and salts to the current acetonitrile (ACN) and tetraethylammonium tetrafluoroborate (Et4NBF4) benchmarks, respectively. Herein, phenylacetonitrile (Ph-ACN) has been proposed as a novel alternative solvent to ACN in supercapacitors. To establish the main advantages and drawbacks of such a substitution, Ph-ACN + Et4NBF4 blends were formulated and characterized prior to being compared with the benchmark electrolyte and another alternative electrolyte based on adiponitrile (ADN). While promising results were obtained, the low Et4NBF4 solubility in Ph-ACN seems to be the main limiting factor. To solve such an issue, an ionic liquid (IL), namely 1-ethyl-3-methylimidazolium bis [(trifluoromethyl)sulfonyl] imide (EmimTFSI), was proposed to replace Et4NBF4. Unsurprisingly, the Ph-ACN + EmimTFSI blend was found to be fully miscible over the whole range of composition giving thus the flexibility to optimize the electrolyte formulation over a large range of IL concentrations up to 4.0 M. The electrolyte containing 2.7 M of EmimTFSI in Ph-ACN was identified as the optimized blend thanks to its interesting transport properties. Furthermore, this blend possesses also the prerequisites of a safe electrolyte, with an operating liquid range from at least −60 °C to +130 °C, and operating window of 3.0 V and more importantly, a flash point of 125 °C. Finally, excellent electrochemical performances were observed by using this electrolyte in a symmetric supercapacitor configuration, showing another advantage of mixing an ionic liquid with Ph-ACN. We also supported key structural descriptors by density functional theory (DFT) and COnductor-like Screening Model for Real Solvents (COSMO-RS) calculations, which can be associated to physical and electrochemical properties of the resultant electrolytes. Full article
(This article belongs to the Special Issue Ionic Liquids, from Their Synthesis to Their Applications)
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Open AccessFeature PaperArticle
Comparing the Thermal and Electrochemical Stabilities of Two Structurally Similar Ionic Liquids
Molecules 2020, 25(10), 2388; https://doi.org/10.3390/molecules25102388 - 21 May 2020
Cited by 2 | Viewed by 729
Abstract
Here we focus on the thermal and variable temperature electrochemical stabilities of two ionic liquids (ILs) having a common tributyloctyl phosphonium cation [P4,4,4,8]+ and two different orthoborate anions: bis(mandelato)borate [BMB] and bis(salicylato)borate [BScB]. The thermo-gravimetric analysis data [...] Read more.
Here we focus on the thermal and variable temperature electrochemical stabilities of two ionic liquids (ILs) having a common tributyloctyl phosphonium cation [P4,4,4,8]+ and two different orthoborate anions: bis(mandelato)borate [BMB] and bis(salicylato)borate [BScB]. The thermo-gravimetric analysis data suggest that [P4,4,4,8][BScB] is thermally more stable than [P4,4,4,8][BMB] in both nitrogen atmosphere and air, while the impedance spectroscopy reveals that [P4,4,4,8][BScB] has higher ionic conductivity than [P4,4,4,8][BMB] over the whole studied temperature range. In contrast, the electrochemical studies confirm that [P4,4,4,8][BMB] is more stable and exhibits a wider electrochemical stability window (ESW) on a glassy carbon electrode surface as compared to [P4,4,4,8][BScB]. A continuous decrease in the ESWs of both ILs is observed as a function of operation temperature. Full article
(This article belongs to the Special Issue Ionic Liquids, from Their Synthesis to Their Applications)
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Open AccessArticle
Ketoprofen-Based Ionic Liquids: Synthesis and Interactions with Bovine Serum Albumin
Molecules 2020, 25(1), 90; https://doi.org/10.3390/molecules25010090 - 25 Dec 2019
Cited by 6 | Viewed by 1199
Abstract
The development of ionic liquids based on active pharmaceutical ingredients (API-ILs) is a possible solution to some of the problems of solid and/or hydrophobic drugs such as low solubility and bioavailability, polymorphism and an alternative route of administration could be suggested as compared [...] Read more.
The development of ionic liquids based on active pharmaceutical ingredients (API-ILs) is a possible solution to some of the problems of solid and/or hydrophobic drugs such as low solubility and bioavailability, polymorphism and an alternative route of administration could be suggested as compared to the classical drug. Here, we report for the first time the synthesis and detailed characterization of a series of ILs containing a cation amino acid esters and anion ketoprofen (KETO-ILs). The affinity and the binding mode of the KETO-ILs to bovine serum albumin (BSA) were assessed using fluorescence spectroscopy. All compounds bind in a distance not longer than 6.14 nm to the BSA fluorophores. The estimated binding constants (KA) are in order of 105 L mol−1, which is indicative of strong drug or IL-BSA interactions. With respect to the ketoprofen-BSA system, a stronger affinity of the ILs containing l-LeuOEt, l-ValOBu, and l-ValOEt cation towards BSA is clearly seen. Fourier transformed infrared spectroscopy experiments have shown that all studied compounds induced a rearrangement of the protein molecule upon binding, which is consistent with the suggested static mechanism of BSA fluorescence quenching and formation of complexes between BSA and the drugs. All tested compounds were safe for macrophages. Full article
(This article belongs to the Special Issue Ionic Liquids, from Their Synthesis to Their Applications)
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Open AccessArticle
The Relationship between the Structure and Properties of Amino Acid Ionic Liquids
Molecules 2019, 24(18), 3252; https://doi.org/10.3390/molecules24183252 - 06 Sep 2019
Cited by 4 | Viewed by 1074
Abstract
Ionic liquids based on different l-amino acids (glycine, l-valine, l-leucine, l-isoleucine, l-histidine, l-methionine, l-tyrosine, l-tryptophan, l-arginine, and l-threonine) and different cations (tetrabutylammonium (TBA), tributylmethylammonium (tBMA), didecyldimethylammonium (DDA), (2-hydroxyethyl)trimethylammonium (choline) (Chol), alkyl(C12-C [...] Read more.
Ionic liquids based on different l-amino acids (glycine, l-valine, l-leucine, l-isoleucine, l-histidine, l-methionine, l-tyrosine, l-tryptophan, l-arginine, and l-threonine) and different cations (tetrabutylammonium (TBA), tributylmethylammonium (tBMA), didecyldimethylammonium (DDA), (2-hydroxyethyl)trimethylammonium (choline) (Chol), alkyl(C12-C14) dimethylbenzylammonium (benzalkonium) (BA), dodecyltrimethylammonium (DDTMA), hexadecyltrimethylammonium (HDTMA), octadecyltrimethylammonium (ODTMA) and 1-ethyl-3-methylimidazolium (EMIM)) have been synthesized and characterized by NMR and FTIR. Viscosity, specific rotation, surface activity, thermal stability (TG), and phase transformations (DSC) have been determined and compared with available data. Furthermore, benzalkonium, didecyldimethylammonium, dodecyltrimethylammonium, hexadecyltrimethylammonium, and octadecyltrimethylammonium amino acid ionic liquids have been shown to exhibit surface activity. The dissolution of cellulose in amino acid ionic liquids (AAILs) composed of various cations was also investigated. Cellulose was only dissolved in EMIM salts of amino acids. In particular, the influence of the cation type on selected physicochemical and spectroscopic properties were discussed. The article is a mini review on amino acid ionic liquids. Full article
(This article belongs to the Special Issue Ionic Liquids, from Their Synthesis to Their Applications)
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Open AccessArticle
Efficient Extraction of Anti-Inflammatory Active Ingredients from Schefflera octophylla Leaves Using Ionic Liquid-Based Ultrasonic-Assisted Extraction Coupled with HPLC
Molecules 2019, 24(16), 2942; https://doi.org/10.3390/molecules24162942 - 14 Aug 2019
Cited by 3 | Viewed by 996
Abstract
Schefflera octophylla (Lour.) Harms, a kind of traditional Chinese medicine (TCM), is commonly used for anti-inflammatory, analgesic, rheumatism, fever, and hemostasis therapy. In our previous studies, two major triterpenoids were isolated and identified from leaves of S. octophylla, and evaluated for their [...] Read more.
Schefflera octophylla (Lour.) Harms, a kind of traditional Chinese medicine (TCM), is commonly used for anti-inflammatory, analgesic, rheumatism, fever, and hemostasis therapy. In our previous studies, two major triterpenoids were isolated and identified from leaves of S. octophylla, and evaluated for their inhibitory effects on lipopolysaccharide (LPS)-induced nitric oxide production in RAW264.7 cells; both of them displayed significant anti-inflammatory activities at their noncytotoxic concentrations. Therefore, it is very useful to establish an efficient and green extraction method to isolated the two major triterpenoids from leaves of S. octophylla. In this paper, ionic liquid based ultrasonic-assisted extraction (ILUAE) was successfully applied to extract the two major triterpenoids from leaves of S. octophylla. Four single factors (ionic liquids (ILs) concentration, solid–liquid ratio, centrifugal speed, mesh number), with a greater impact on extraction rate, were selected from a variety of influencing factors, and the optimal conditions were obtained by Box–Behnken response surface methodology (RSM). Under optimal conditions, the total extraction yield and extraction rate of two triterpenoids were 288.03 mg/g and 28.80%, respectively, which was 6.80% higher than that of 70% Ethanol (220 mg/g and 22%, respectively). Full article
(This article belongs to the Special Issue Ionic Liquids, from Their Synthesis to Their Applications)
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Open AccessArticle
Estimating the Solubility, Solution Thermodynamics, and Molecular Interaction of Aliskiren Hemifumarate in Alkylimidazolium Based Ionic Liquids
Molecules 2019, 24(15), 2807; https://doi.org/10.3390/molecules24152807 - 01 Aug 2019
Cited by 8 | Viewed by 910
Abstract
Estimating the solubility and solution thermodynamics parameters of aliskiren hemifumarate (AHF) in three different room temperature ionic liquids (RTILs), Transcutol-HP (THP) and water are interesting as there is no solubility data available in the literature. In the current study, the solubility and solution [...] Read more.
Estimating the solubility and solution thermodynamics parameters of aliskiren hemifumarate (AHF) in three different room temperature ionic liquids (RTILs), Transcutol-HP (THP) and water are interesting as there is no solubility data available in the literature. In the current study, the solubility and solution thermodynamics of AHF in three different RTILs, THP and water at the temperature range from 298.2 to 318.2 K under air pressure 0.1 MP were evaluated. The solid phase evaluation by Differential Scanning Calorimetry (DSC) and Powder X-ray Diffraction (PXRD) indicated no conversion of AHF into polymorph. The mole fraction solubility of AHF was found to be highest in 1-hexyl-3-methylimidazolium hexafluorophosphate (HMMHFP) ionic liquid (7.46 × 10−2) at 318.2 K. The obtained solubility values of AHF was regressed by the Apelblat and van’t Hoff models with overall root mean square deviations (RMSD) of 0.62% and 1.42%, respectively. The ideal solubility of AHF was higher compared to experimental solubility values at different temperatures. The lowest activity coefficient was found in HMMHFP, which confirmed highest molecular interaction between AHF–HMMHFP. The estimated thermodynamic parameters confirmed endothermic and entropy driven dissolution of AHF in different RTILs, THP, and water. Full article
(This article belongs to the Special Issue Ionic Liquids, from Their Synthesis to Their Applications)
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Review

Jump to: Research

Open AccessFeature PaperReview
Industrial Applications of Ionic Liquids
Molecules 2020, 25(21), 5207; https://doi.org/10.3390/molecules25215207 - 09 Nov 2020
Cited by 7 | Viewed by 1290
Abstract
Since their conception, ionic liquids (ILs) have been investigated for an extensive range of applications including in solvent chemistry, catalysis, and electrochemistry. This is due to their designation as designer solvents, whereby the physiochemical properties of an IL can be tuned for specific [...] Read more.
Since their conception, ionic liquids (ILs) have been investigated for an extensive range of applications including in solvent chemistry, catalysis, and electrochemistry. This is due to their designation as designer solvents, whereby the physiochemical properties of an IL can be tuned for specific applications. This has led to significant research activity both by academia and industry from the 1990s, accelerating research in many fields and leading to the filing of numerous patents. However, while ILs have received great interest in the patent literature, only a limited number of processes are known to have been commercialised. This review aims to provide a perspective on the successful commercialisation of IL-based processes, to date, and the advantages and disadvantages associated with the use of ILs in industry. Full article
(This article belongs to the Special Issue Ionic Liquids, from Their Synthesis to Their Applications)
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Open AccessReview
Synthesis and Dissolution of Metal Oxides in Ionic Liquids and Deep Eutectic Solvents
Molecules 2020, 25(1), 78; https://doi.org/10.3390/molecules25010078 - 24 Dec 2019
Cited by 16 | Viewed by 1704
Abstract
Ionic liquids (ILs) and deep eutectic solvents (DESs) have proven to be suitable solvents and reactants for low-temperature reactions. To date, several attempts were made to apply this promising class of materials to metal oxide chemistry, which, conventionally, is performed at high temperatures. [...] Read more.
Ionic liquids (ILs) and deep eutectic solvents (DESs) have proven to be suitable solvents and reactants for low-temperature reactions. To date, several attempts were made to apply this promising class of materials to metal oxide chemistry, which, conventionally, is performed at high temperatures. This review gives an overview about the scientific approaches of the synthesis as well as the dissolution of metal oxides in ILs and DESs. A wide range of metal oxides along with numerous ILs and DESs are covered by this research. With ILs and DESs being involved, many metal oxide phases as well as different particle morphologies were obtained by means of relatively simple reactions paths. By the development of acidic task-specific ILs and DESs, even difficultly soluble metal oxides were dissolved and, hence, made accessible for downstream chemistry. Especially the role of ILs in these reactions is in the focus of discussion. Full article
(This article belongs to the Special Issue Ionic Liquids, from Their Synthesis to Their Applications)
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