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Special Issue "Deep Eutectic Solvents"

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

Deadline for manuscript submissions: closed (15 October 2019).

Special Issue Editors

Prof. Mert Atilhan
E-Mail Website
Guest Editor
Department of Chemical Engineering, Texas A&M University at Qatar, Gas & Fuels Research Center, Texas A&M University at College Station, Doha, Qatar
Interests: ionic liquids; deep and natural deep eutectic solvents; porous materials; gas capture and storage, gas hydrates; vapor–liquid equilibrium and chemical thermodynamics
Prof. Santiago Aparicio
E-Mail Website
Guest Editor
University of Burgos, Department of Chemistry, Burgos, Spain
Interests: molecular modeling; thermodynamics; ionic liquids; deep eutectic solvents; CO2 capture; nano-materials; phase equilibrium; physical chemistry

Special Issue Information

Dear Colleagues,

Deep eutectic solvents (DES), being cost-effective solvents, have attracted increasing attention in both academia and industry in recent years. Bringing together mixtures of hydrogen-bond donor(s) and hydrogen-bond acceptor(s), DESs are formed and such mixtures show substantially high melting-point depression upon mixing.

Due to their task-specific character, DES have recently been considered as alternatives to current industry benchmark solvents since DES maintain most of their relevant properties and at the same DESs time avoid some of their economic and environmental issues. DES are produced from low cost and natural sources, together with their almost null toxicity and high biodegradability make them solvents as a suitable for wide range of applications such as organic synthesis, catalysis, biocatalysis, biodiesel transformation, electrochemistry, batteries and capacitors, (nano)materials, pharmaceutical ingredient delivery vehicles and gas separation technologies.

The purpose of this Special Issue on DES in Molecules is to bring experts from the fields of chemistry, chemical engineering and materials science backgrounds and highlight recent advancements in above-mentioned areas for these innovative solvents and their applications. We welcome both experimental and theoretical approaches in order to diversify this special issue and give broader perspective on the subject to the readers.

We hope this Special Issue will catalyze the ongoing research activities on DES and inspire many others in both academia and industry to consider promising novel solvents, DES, as one of the most state-of-the-art mediums for sustainable chemical process applications.

Prof. Mert Atilhan
Prof. Santiago Aparicio
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 1800 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

  • Deep Eutectic Solvents
  • Ionic Liquids
  • Organic Acids
  • Gas Solubility
  • Gas Separation
  • Natural Deep Eutectic Solvents
  • Density Functional Theory
  • Molecular Dynamics
  • Organic Synthesis
  • Catalysis
  • Biocatalysis
  • Biodiesel Transformation
  • Electrochemistry
  • Batteries and Capacitors
  • Nano-materials
  • Drug Delivery

Published Papers (5 papers)

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Research

Open AccessFeature PaperArticle
The Role of Charge Transfer in the Formation of Type I Deep Eutectic Solvent-Analogous Ionic Liquid Mixtures
Molecules 2019, 24(20), 3687; https://doi.org/10.3390/molecules24203687 - 14 Oct 2019
Abstract
It was recently shown that tetramethylammonium chloride presented negative deviations to ideality when mixed with tetraethylammonium chloride or tetrapropylammonium chloride, leading to a strong decrease of the melting points of these salt mixtures, in a behavior akin to that observed in the formation [...] Read more.
It was recently shown that tetramethylammonium chloride presented negative deviations to ideality when mixed with tetraethylammonium chloride or tetrapropylammonium chloride, leading to a strong decrease of the melting points of these salt mixtures, in a behavior akin to that observed in the formation of deep eutectic solvents. To better rationalize this unexpected melting point depression between two structurally similar compounds devoid of dominant hydrogen bonding capability, new solid–liquid equilibria data for tetramethylammonium-based systems were measured and analyzed in this work. Molecular dynamics was used to show that the strong negative deviations from ideality presented by these systems arise from a synergetic share of the chloride ions. A transfer of chloride ions seems to occur from the bigger cation in the mixture (which possesses a more disperse charge) to the smaller cation (tetramethylammonium), resembling the formation of metal–chloride complexes in type I deep eutectic solvents. This rearrangement of the charged species leads to an energetic stabilization of both components in the mixture, inducing the negative deviations to the ideality observed. The conclusions presented herein emphasize the often-neglected contribution of charge delocalization in deep eutectic solvents formation and its applicability toward the design of new ionic liquid mixtures. Full article
(This article belongs to the Special Issue Deep Eutectic Solvents)
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Open AccessFeature PaperArticle
Quantum Chemistry Insight into the Interactions Between Deep Eutectic Solvents and SO2
Molecules 2019, 24(16), 2963; https://doi.org/10.3390/molecules24162963 - 15 Aug 2019
Abstract
A systematic research work on the rational design of task specific Deep Eutectic Solvents (DES) has been carried out via density functional theory (DFT) in order to increase knowledge on the key interaction parameters related to efficient SO2 capture by DES at [...] Read more.
A systematic research work on the rational design of task specific Deep Eutectic Solvents (DES) has been carried out via density functional theory (DFT) in order to increase knowledge on the key interaction parameters related to efficient SO2 capture by DES at a molecular level. A total of 11 different DES structures, for which high SO2 affinity and solubility is expected, have been selected in this work. SO2 interactions in selected DES were investigated in detail through DFT simulations and this work has generated a valuable set of information about required factors at the molecular level to provide high SO2 solubility in DES, which is crucial for enhancing the current efficiency of the SO2 capture process and replacing the current state of the art with environmentally friendly solvents and eventually implementing these materials in the chemical industry. Results that were obtained from DFT calculations were used to deduce the details of the type and the intensity of the interaction between DES and SO2 molecules at various interaction sites as well as to quantify short-range interactions by using various methods such as quantum theory of atoms in a molecule (QTAIM), electrostatic potentials (ESP) and reduced density gradients (RDG). Systematic research on the molecular interaction characterization between DES structures and SO2 molecule increases our knowledge on the rational design of task-specific DES. Full article
(This article belongs to the Special Issue Deep Eutectic Solvents)
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Open AccessArticle
Modeling of Solid–Liquid Equilibria in Deep Eutectic Solvents: A Parameter Study
Molecules 2019, 24(12), 2334; https://doi.org/10.3390/molecules24122334 - 25 Jun 2019
Abstract
Deep eutectic solvents (DESs) are potential alternatives to many conventional solvents in process applications. Knowledge and understanding of solid–liquid equilibria (SLE) are essential to characterize, design, and select a DES for a specific application. The present study highlights the main aspects that should [...] Read more.
Deep eutectic solvents (DESs) are potential alternatives to many conventional solvents in process applications. Knowledge and understanding of solid–liquid equilibria (SLE) are essential to characterize, design, and select a DES for a specific application. The present study highlights the main aspects that should be taken into account to yield better modeling, prediction, and understanding of SLE in DESs. The work is a comprehensive study of the parameters required for thermodynamic modeling of SLE—i.e., the melting properties of pure DES constituents and their activity coefficients in the liquid phase. The study is carried out for a hypothetical binary mixture as well as for selected real DESs. It was found that the deepest eutectic temperature is possible for components with low melting enthalpies and strong negative deviations from ideality in the liquid phase. In fact, changing the melting enthalpy value of a component means a change in the difference between solid and liquid reference state chemical potentials which results in different values of activity coefficients, leading to different interpretations and even misinterpretations of interactions in the liquid phase. Therefore, along with reliable modeling of liquid phase non-ideality in DESs, accurate estimation of the melting properties of their pure constituents is of clear significance in understanding their SLE behavior and for designing new DES systems. Full article
(This article belongs to the Special Issue Deep Eutectic Solvents)
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Open AccessArticle
Permeabilities of CO2, H2S and CH4 through Choline-Based Ionic Liquids: Atomistic-Scale Simulations
Molecules 2019, 24(10), 2014; https://doi.org/10.3390/molecules24102014 - 27 May 2019
Abstract
Molecular dynamics simulations are used to study the transport of CO2, H2S and CH4 molecules across environmentally friendly choline-benzoate and choline-lactate ionic liquids (ILs). The permeability coefficients of the considered molecules are calculated using the free energy and [...] Read more.
Molecular dynamics simulations are used to study the transport of CO 2 , H 2 S and CH 4 molecules across environmentally friendly choline-benzoate and choline-lactate ionic liquids (ILs). The permeability coefficients of the considered molecules are calculated using the free energy and diffusion rate profiles. Both systems show the largest resistance to CH 4 , whereas more than 5 orders of magnitude larger permeability coefficients are obtained for the other two gas molecules. The CO 2 /CH 4 and H 2 S/CH 4 selectivity was estimated to be more than 10 4 and 10 5 , respectively. These results indicate the great potential of the considered ILs for greenhouse gas control. Full article
(This article belongs to the Special Issue Deep Eutectic Solvents)
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Open AccessArticle
Deep Eutectic Solvent-Based Ultrahigh Pressure Extraction of Baicalin from Scutellaria baicalensis Georgi
Molecules 2018, 23(12), 3233; https://doi.org/10.3390/molecules23123233 - 07 Dec 2018
Cited by 2
Abstract
Deep eutectic solvents (DESs), promising green solvents, and ultrahigh pressure extraction (UPE) as an effective auxiliary extraction method, have attracted wide attention. In this study, DES was coupled with UPE to efficiently extract baicalin from Scutellaria baicalensis Georgi. First, choline chloride: lactic acid [...] Read more.
Deep eutectic solvents (DESs), promising green solvents, and ultrahigh pressure extraction (UPE) as an effective auxiliary extraction method, have attracted wide attention. In this study, DES was coupled with UPE to efficiently extract baicalin from Scutellaria baicalensis Georgi. First, choline chloride: lactic acid (ChCl-LA, molar ratio 1:1) was selected as the most appropriate DES by comparing the extraction yield of different DESs. Second, the extraction protocol was optimized by response surface methodology (RSM) considering the impacts of ChCl-LA concentration, extraction pressure, extraction time and liquid-solid ratio on the extraction yield. Under the optimal condition (40 vol% water content, extraction pressure of 400 MPa, extraction time of 4 min and a liquid-solid ratio of 110 mL/g), a maximum yield of 116.8 mg/g was achieved, higher than that obtained by the traditional extraction method. The microstructure of the raw and extracted Scutellaria baicalensis Georgi samples according to scanning electron microscope (SEM) images revealed that the dissolution of chemical components was enhanced from the disrupted root tissues after DESs-UPE. DESs coupled with UPE could effectively extract the baicalin from Scutellaria baicalensis Georgi as a rapid and efficient extraction method. Full article
(This article belongs to the Special Issue Deep Eutectic Solvents)
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