The Structure of Imidazolium-Based Ionic Liquids: Insights From Ion-Pair Interactions

2007 ◽  
Vol 60 (1) ◽  
pp. 9 ◽  
Author(s):  
Patricia A. Hunt ◽  
Ian R. Gould ◽  
Barbara Kirchner
Keyword(s):  
Ionic Liquids ◽  
Melting Point ◽  
Ion Pairs ◽  
Liquid Structure ◽  
High Viscosity ◽  
Ion Pair ◽  
Low Viscosity ◽  
Association Energy ◽  
Dynamics Simulations ◽  
Insight Into

A large number of ab-initio (B3LYP/6–31++G(d,p)) computed ion-pair structures have been examined in order to determine if such calculations are capable of offering insight into the physical properties of the liquid state, particularly viscosity and melting point. Ion pairings based around the 1-butyl-3-methylimidazolium (C4C1im) cations and a range of anions (Cl, BF4, and N(Tf)2 where N(Tf)2 is bis(trifluoromethylsulfonly)imide) were chosen because of the range of viscosities exhibited by the corresponding ionic liquids. We have used these results to build up a ‘picture’ of the ionic liquid structure which is consistent with molecular dynamics simulations and experimental evidence. However, further work is required to established if such an analysis could be predictive. Nevertheless, we establish clear relationships relating ion-pair association energy, a derived ‘connectivity index’, and the diversity of structures with viscosity and melting point. Our calculations indicate that ions in C4C1imCl form a strong, highly connected and regular array thus rationalizing the high viscosity and melting point. In contrast the ion-pairs of C4C1imN(Tf)2 form a weakly interacting, highly disordered, and low connectivity network consistent with the low viscosity and melting point. C4C1imBF4 lies midway between these two extremes.

Dynamics of Ion Locking in Doubly Polymerized Ionic Liquids

2020 ◽  
Author(s):  
Swati Arora ◽  
Julisa Rozon ◽  
Jennifer Laaser
Keyword(s):  
Dielectric Constant ◽  
Ionic Liquid ◽  
Ionic Liquids ◽  
Ion Pairs ◽  
Polymer Chains ◽  
Ion Motion ◽  
Charged Species ◽  
Broadband Dielectric Spectroscopy ◽  
Covalently Linked ◽  
Insight Into

<div>In this work, we investigate the dynamics of ion motion in “doubly-polymerized” ionic liquids (DPILs) in which both charged species of an ionic liquid are covalently linked to the same polymer chains. Broadband dielectric spectroscopy is used to characterize these materials over a broad frequency and temperature range, and their behavior is compared to that of conventional “singly-polymerized” ionic liquids (SPILs) in which only one of the charged species is attached to the polymer chains. Polymerization of the DPIL decreases the bulk ionic conductivity by four orders of magnitude relative to both SPILs. The timescales for local ionic rearrangement are similarly found to be approximately four orders of magnitude slower in the DPILs than in the SPILs, and the DPILs also have a lower static dielectric constant. These results suggest that copolymerization of the ionic monomers affects ion motion on both the bulk and the local scales, with ion pairs serving to form strong physical crosslinks between the polymer chains. This study provides quantitative insight into the energetics and timescales of ion motion that drive the phenomenon of “ion locking” currently under investigation for new classes of organic electronics.</div>

scholarly journals Predicting Melting Points of Biofriendly Choline-Based Ionic Liquids with Molecular Dynamics

2019 ◽  
Vol 9 (24) ◽  
pp. 5367 ◽  
Author(s):  
Karl Karu ◽  
Fred Elhi ◽  
Kaija Põhako-Esko ◽  
Vladislav Ivaništšev
Keyword(s):  
Crystal Structure ◽  
Molecular Dynamics ◽  
Ionic Liquids ◽  
Melting Point ◽  
Chemical Space ◽  
Mean Square ◽  
Melting Points ◽  
Simulation Based ◽  
Predicted Values ◽  
Dynamics Simulations

In this work, we introduce a simulation-based method for predicting the melting point of ionic liquids without prior knowledge of their crystal structure. We run molecular dynamics simulations of biofriendly, choline cation-based ionic liquids and apply the method to predict their melting point. The root-mean-square error of the predicted values is below 24 K. We advocate that such precision is sufficient for designing ionic liquids with relatively low melting points. The workflow for simulations is available for everyone and can be adopted for any species from the wide chemical space of ionic liquids.

Density Functional Theory Study on the Absorption of CO2 by the Ionic Liquid of 1-butyl-3-methylimidazolium Acetate

2013 ◽  
Vol 807-809 ◽  
pp. 543-548 ◽  
Author(s):  
Yan Fei Chen ◽  
Yan Hong Cui ◽  
Dong Shun Deng ◽  
Ning Ai
Keyword(s):  
Density Functional Theory ◽  
Ionic Liquid ◽  
Ionic Liquids ◽  
Density Functional ◽  
Ion Pairs ◽  
Ion Pair ◽  
Frontier Molecular Orbitals ◽  
Density Functional Theory Study ◽  
Electronic Density ◽  
Functional Theory

The absorptions of CO2on the 1-butyl-3-methylimidazolium acetate ([Bmi [Ac]) with different substituents are calculated systematically at GGA/PW91 level. Three hydrogen bonds are formed between [A and cations of 1-n-[Bmi [A ([NBmi+) and 1-tert-[Bmi [A ([TBmi+). The interaction between CO2and the [NBmi [A by a C-O bond is much weaker than that with the [TBmi [A by forming a O...O...C...C four member-ring. The chemisorption of CO2on the ion pairs of [NBmi [A is much weaker than that on the [TBmi [A, resulted from the absorption energies analysis. The frontier molecular orbitals shows the electronic density overlap between absorbed CO2and the [A in CO2-[NBmi [A is much weaker than that in [TBmi [A. Therefore, the chemisorption of CO2on the ion pair of [NBmi [A is much weaker than that on the [TBmi [A. The ionic liquids based [NBmi+can be used repetitively, and the adsorbed CO2would be easier desorbed.

scholarly journals Specifically Designed Ionic Liquids—Formulations, Physicochemical Properties, and Electrochemical Double Layer Storage Behavior

2019 ◽  
Vol 3 (2) ◽  
pp. 58
Author(s):  
Zheng Yue ◽  
Qiang Ma ◽  
Xinyi Mei ◽  
Abigail Schulz ◽  
Hamza Dunya ◽  
...  
Keyword(s):  
Ionic Liquids ◽  
High Viscosity ◽  
Li Ion Batteries ◽  
The Past ◽  
Low Viscosity ◽  
Electrolytic Properties ◽  
Storage Behavior ◽  
Li Ion ◽  
Key Features ◽  
Electrochemical Double Layer

Two key features—non-volatility and non-flammability—make ionic liquids (ILs) very attractive for use as electrolyte solvents in advanced energy storage systems, such as supercapacitors and Li-ion batteries. Since most ILs possess high viscosity and are less prone to dissolving common electrolytic salts when compared to traditional electrolytic solvents, they must be formulated with low viscosity thinner solvents to achieve desired ionic conductivity and dissolution of electrolyte salts in excess of 0.5 M concentration. In the past few years, our research group has synthesized several specifically designed ILs (mono-cationic, di-cationic, and zwitterionic) with bis(trifluoromethylsulfonyl)imide (TFSI) and dicyanamide (DCA) as counter anions. This article describes several electrolyte formulations to achieve superior electrolytic properties. The performance of a few representative IL-based electrolytes in supercapacitor coin cells is presented.

Protic ammonium carboxylate ionic liquids: insight into structure, dynamics and thermophysical properties by alkyl group functionalization

2017 ◽  
Vol 19 (16) ◽  
pp. 10358-10370 ◽  
Author(s):  
Th. Dhileep N. Reddy ◽  
Bhabani S. Mallik
Keyword(s):  
Molecular Dynamics ◽  
Ionic Liquids ◽  
Molecular Dynamics Simulations ◽  
Thermophysical Properties ◽  
Alkyl Group ◽  
Structure Dynamics ◽  
Classical Molecular Dynamics ◽  
Dynamics Simulations ◽  
Insight Into

This study is aimed at characterising the structure, dynamics and thermophysical properties of five alkylammonium carboxylate ionic liquids (ILs) from classical molecular dynamics simulations.

Chloride-dependent conformational changes in the GlyT1 glycine transporter

2020 ◽  
Author(s):  
Yuan-Wei Zhang ◽  
Stacy Uchendu ◽  
Vanessa Leone ◽  
Richard T. Bradshaw ◽  
Ntumba Sangwa ◽  
...  
Keyword(s):  
Conformational Changes ◽  
Ion Pair ◽  
Cysteine Residues ◽  
Glycine Transporter ◽  
Open Conformation ◽  
Transporter Family ◽  
Transport Cycle ◽  
Dynamics Simulations ◽  
Insight Into

AbstractThe human GlyT1 glycine transporter requires chloride for its function. However, the mechanism by which Cl- exerts its influence is unknown. To examine the role that Cl- plays in the transport cycle, we measured the effect of Cl- on both glycine binding and conformational changes. The ability of glycine to displace the high-affinity radioligand [3H]CHIBA-3007 required Na+ and was potentiated over 1000-fold by Cl-. We generated GlyT1b mutants containing reactive cysteine residues in either the extracellular or cytoplasmic permeation pathways and measured changes in the reactivity of those cysteine residues as indicators of conformational changes in response to ions and substrate. Na+ increased accessibility in the extracellular pathway and decreased it in the cytoplasmic pathway, consistent with stabilizing an outward-open conformation as observed in other members of this transporter family. In the presence of Na+, both glycine and Cl- independently shifted the conformation of GlyT1b toward an outward-closed conformation. Together, Na+, glycine and Cl- stabilized an inward-open conformation of GlyT1b. We then examined whether Cl- acts by interacting with a conserved glutamine to allow formation of an ion pair that stabilizes the closed state of the extracellular pathway. Molecular dynamics simulations of a GlyT1 homologue indicated that this ion pair is formed more frequently as that pathway closes. Mutation of the glutamine blocked the effect of Cl-, and substituting it with glutamate or lysine resulted in outward- or inward-facing transporter conformations, respectively. These results provide novel and unexpected insight into the role of Cl- in this family of transporters.

MD Studies of Transport in Polymer-Salt Complexes: A Progress Report

1990 ◽  
Vol 210 ◽  
Author(s):  
M. Forsyth ◽  
V. A. Payne ◽  
M. A. Ratner ◽  
S. W. De Leeuw ◽  
D. F. Shriver
Keyword(s):  
Polymer Electrolytes ◽  
Ion Pairs ◽  
Solvent Molecule ◽  
Ion Pair ◽  
Pair Formation ◽  
Progress Report ◽  
Lennard Jones ◽  
Solvent Model ◽  
Solvent Systems ◽  
Dynamics Simulations

AbstractMolecular dynamics simulations performed on highly concentrated Coulomb/solvent systems are used to help interpret the transport mechanism in polymer ionics. Using simple Coulomb and Lennard-Jones forces among the ions and a solvent model of a fixed dipole contained in a spherical solvent particle, we investigated the nature of ion pair formation and stability. For a model NaI system, we find that ion pairs decrease with increase in solvent dipole moment or temperature. The latter observation is at variance with experimental results on polymer electrolytes, probably because of entropy terms that do not occur with our simple solvent molecule.

Dynamics of Ion Locking in Doubly Polymerized Ionic Liquids

2020 ◽  
Author(s):  
Swati Arora ◽  
Julisa Rozon ◽  
Jennifer Laaser
Keyword(s):  
Dielectric Constant ◽  
Ionic Liquid ◽  
Ionic Liquids ◽  
Ion Pairs ◽  
Polymer Chains ◽  
Ion Motion ◽  
Charged Species ◽  
Broadband Dielectric Spectroscopy ◽  
Covalently Linked ◽  
Insight Into

<div>In this work, we investigate the dynamics of ion motion in “doubly-polymerized” ionic liquids (DPILs) in which both charged species of an ionic liquid are covalently linked to the same polymer chains. Broadband dielectric spectroscopy is used to characterize these materials over a broad frequency and temperature range, and their behavior is compared to that of conventional “singly-polymerized” ionic liquids (SPILs) in which only one of the charged species is attached to the polymer chains. Polymerization of the DPIL decreases the bulk ionic conductivity by four orders of magnitude relative to both SPILs. The timescales for local ionic rearrangement are similarly found to be approximately four orders of magnitude slower in the DPILs than in the SPILs, and the DPILs also have a lower static dielectric constant. These results suggest that copolymerization of the ionic monomers affects ion motion on both the bulk and the local scales, with ion pairs serving to form strong physical crosslinks between the polymer chains. This study provides quantitative insight into the energetics and timescales of ion motion that drive the phenomenon of “ion locking” currently under investigation for new classes of organic electronics.</div>

Molecular Dynamics Simulations of Ionic Liquids: Influence of Polarization on IL Structure and Ion Transport

2008 ◽  
Vol 1082 ◽  
Author(s):  
Oleg Borodin
Keyword(s):  
Molecular Dynamics ◽  
Ionic Liquid ◽  
Ionic Liquids ◽  
Condensed Phase ◽  
Wide Class ◽  
Md Simulations ◽  
Liquid Structure ◽  
Many Body ◽  
Polarizable Force Field ◽  
Dynamics Simulations

ABSTRACTMany-body polarizable force field has been developed and validated for a wide class of ionic liquids. Classical molecular dynamics (MD) simulations have been performed on 29 ionic liquids. This presentation will focus on ability of developed force fields to predict condensed phase properties and on understanding the influence of many-body polarizable interactions on the ionic liquid structure and transport.

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