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Computational Physics and Chemistry Contributions to the Investigation of Ionic Liquids

A special issue of Entropy (ISSN 1099-4300). This special issue belongs to the section "Statistical Physics".

Deadline for manuscript submissions: closed (31 July 2023) | Viewed by 3782

Special Issue Editors


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Guest Editor
Istituto Dei Sistemi Complessi, Consiglio Nazionale delle Ricerche, 00185 Rome, Italy
Interests: Ionic liquids; deep eutectic solvents; fundamental properties and applications; theory and experiments
Special Issues, Collections and Topics in MDPI journals

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Guest Editor
Italian National Research Council - Istituto Dei Sistemi Complessi, 00185 Rome, Italy
Interests: ionic liquids; hydrogen; energy
Special Issues, Collections and Topics in MDPI journals

Special Issue Information

Dear Colleagues,

Ionic liquids have largely been investigated for their peculiar experimental properties and their uncountable applications. From a computational point of view, they pose many challenges, mainly because they are composed of ions, and at ambient temperature and pressure most of them take liquid form, lacking a periodic structure. Describing mixtures of ionic liquids with other ionic liquids or molecular solvents is an even greater challenge.

Computational chemistry and physics provide important contributions for understanding the reported properties of ionic liquids and mixtures, rationalizing them and predicting behaviors that have yet to be experimentally investigated.

We invite contributions to this Special Issue concerning new computational contributions to explain or rationalize ionic liquids’ properties and their use in real applications.

Dr. Annalisa Paolone
Dr. Oriele Palumbo
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 submissions that pass pre-check are 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. Entropy is an international peer-reviewed open access monthly 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 2600 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

  • density functional theory
  • molecular dynamics
  • ab initio molecular dynamics
  • continuum modeling
  • COSMO methods
  • machine learning

Published Papers (3 papers)

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Research

21 pages, 15331 KiB  
Article
Characterizing Microheterogeneity in Liquid Mixtures via Local Density Fluctuations
by Michael Lass, Tobias Kenter, Christian Plessl and Martin Brehm
Entropy 2024, 26(4), 322; https://doi.org/10.3390/e26040322 - 09 Apr 2024
Viewed by 528
Abstract
We present a novel approach to characterize and quantify microheterogeneity and microphase separation in computer simulations of complex liquid mixtures. Our post-processing method is based on local density fluctuations of the different constituents in sampling spheres of varying size. It can be easily [...] Read more.
We present a novel approach to characterize and quantify microheterogeneity and microphase separation in computer simulations of complex liquid mixtures. Our post-processing method is based on local density fluctuations of the different constituents in sampling spheres of varying size. It can be easily applied to both molecular dynamics (MD) and Monte Carlo (MC) simulations, including periodic boundary conditions. Multidimensional correlation of the density distributions yields a clear picture of the domain formation due to the subtle balance of different interactions. We apply our approach to the example of force field molecular dynamics simulations of imidazolium-based ionic liquids with different side chain lengths at different temperatures, namely 1-ethyl-3-methylimidazolium chloride, 1-hexyl-3-methylimidazolium chloride, and 1-decyl-3-methylimidazolium chloride, which are known to form distinct liquid domains. We put the results into the context of existing microheterogeneity analyses and demonstrate the advantages and sensitivity of our novel method. Furthermore, we show how to estimate the configuration entropy from our analysis, and we investigate voids in the system. The analysis has been implemented into our program package TRAVIS and is thus available as free software. Full article
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11 pages, 1263 KiB  
Article
Some Considerations about the Anodic Limit of Ionic Liquids Obtained by Means of DFT Calculations
by Annalisa Paolone, Simone Di Muzio, Oriele Palumbo and Sergio Brutti
Entropy 2023, 25(5), 793; https://doi.org/10.3390/e25050793 - 12 May 2023
Viewed by 954
Abstract
Ionic liquids are good candidates as the main component of safe electrolytes for high-energy lithium-ion batteries. The identification of a reliable algorithm to estimate the electrochemical stability of ionic liquids can greatly speed up the discovery of suitable anions able to sustain high [...] Read more.
Ionic liquids are good candidates as the main component of safe electrolytes for high-energy lithium-ion batteries. The identification of a reliable algorithm to estimate the electrochemical stability of ionic liquids can greatly speed up the discovery of suitable anions able to sustain high potentials. In this work, we critically assess the linear dependence of the anodic limit from the HOMO level of 27 anions, whose performances have been experimentally investigated in the previous literature. A limited r Pearson’s value of ≈0.7 is found even with the most computationally demanding DFT functionals. A different model considering vertical transitions in a vacuum between the charged state and the neutral molecule is also exploited. In this case, the best-performing functional (M08-HX) provides a Mean Squared Error (MSE) of 1.61 V2 on the 27 anions here considered. The ions which give the largest deviations are those with a large value of the solvation energy, and therefore, an empirical model that linearly combines the anodic limit calculated by vertical transitions in a vacuum and in a medium with a weight dependent on the solvation energy is proposed for the first time. This empirical method can decrease the MSE to 1.29 V2 but still provides an r Pearson’s value of ≈0.72. Full article
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16 pages, 2914 KiB  
Article
Reaction Mechanism of CO2 with Choline-Amino Acid Ionic Liquids: A Computational Study
by Fabio Ramondo and Simone Di Muzio
Entropy 2022, 24(11), 1572; https://doi.org/10.3390/e24111572 - 31 Oct 2022
Cited by 3 | Viewed by 1704
Abstract
Carbon capture and sequestration are the major applied techniques for mitigating CO2 emission. The marked affinity of carbon dioxide to react with amino groups is well known, and the amine scrubbing process is the most widespread technology. Among various compounds and [...] Read more.
Carbon capture and sequestration are the major applied techniques for mitigating CO2 emission. The marked affinity of carbon dioxide to react with amino groups is well known, and the amine scrubbing process is the most widespread technology. Among various compounds and solutions containing amine groups, in biodegradability and biocompatibility perspectives, amino acid ionic liquids (AAILs) are a very promising class of materials having good CO2 absorption capacity. The reaction of amines with CO2 follows a multi-step mechanism where the initial pathway is the formation of the CN bond between the NH2 group and CO2. The added product has a zwitterionic character and can rearrange to give a carbamic derivative. These steps of the mechanism have been investigated in the present study by quantum mechanical methods by considering three ILs where amino acid anions are coupled with choline cations. Glycinate, L-phenylalanilate and L-prolinate anions have been compared with the aim of examining if different local structural properties of the amine group can affect some fundamental steps of the CO2 absorption mechanism. All reaction pathways have been studied by DFT methods considering, first, isolated anions in a vacuum as well as in a liquid continuum environment. Subsequently, the role of specific interactions of the anion with a choline cation has been investigated, analyzing the mechanism of the amine–CO2 reaction, including different coupling anion–cation structures. The overall reaction is exothermic for the three anions in all models adopted; however, the presence of the solvent, described by a continuum medium as well as by models, including specific cation- -anion interactions, modifies the values of the reaction energies of each step. In particular, both reaction steps, the addition of CO2 to form the zwitterionic complex and its subsequent rearrangement, are affected by the presence of the solvent. The reaction enthalpies for the three systems are indeed found comparable in the models, including solvent effects. Full article
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