On the ideality of binary mixtures of ionic liquids

Brüssel, Marc; Brehm, Martin; Pensado, Alfonso S.; Malberg, Friedrich; Ramzan, Muhammad; Stark, Annegret; Kirchner, Barbara

doi:10.1039/c2cp41926b

Cited by 91 publications

(103 citation statements)

References 51 publications

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“…50 Ab initio MD simulations have indicated π + -π + interactions occur in [C 2 C 1 im]X, X=Cland [SCN] -. 51 In π + -π + systems, charge screening via the inclusion of counterions (Figure 1) or a suitable solvent environment (e.g. water) helps to dampen the additional repulsive Coulombic component.…”

Section: Introductionmentioning

confidence: 99%

“…74,75 However, recent studies have shown that more than one IP is required to expand our understanding of IL systems, in general, and more specifically to study the impact of π + -π + interactions. 51,53,76,77 In this paper we expand the electronic structure analysis of ILs to several IP-dimer structures in order to explore characteristics of the intermolecular interactions; H-bonding, anion-π + and π + π + interactions. An array of quantum tools is employed, including Quantum Theory of Atoms in Molecules (QTAIM), 78,79 Natural Bond Orbital (NBO) analysis, 80 Non-Covalent Interaction (NCI) analysis 81 and qualitative molecular orbital (MO) analysis.…”

Section: Introductionmentioning

confidence: 99%

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Hydrogen bonding and π–π interactions in imidazolium-chloride ionic liquid clusters

Matthews

Welton

Hunt

2015

Phys. Chem. Chem. Phys.

114

150

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A systematic electronic structure analysis of hydrogen bonding (H-bonding), anion-π(+) and π(+)-π(+) interactions present in [C1C1im]Cl ion-pairs (IPs) and selected [C1C1im]2Cl2 IP-dimers has been carried out. Interactions have been characterised using a combination of QTAIM, NCIPLOT, NBO and qualitative MO theory. IP-dimers form non-directional charge quadrupolar arrangements due to Coulombic interactions. These are found to associate either as clusters or as loosely associated IP-IP structures. Large conformational changes are found to occur for very little cost in energy, indicating that charge screening is essentially independent of the cation ring orientation. H-bond formation is accompanied by charge transfer and polarisation of the entire [C1C1im](+) ring. Charge transfer does not follow the same trend for the CHelpG, QTAIM and NBO methods. Weak "stacked" π(+)-π(+) interactions are stabilised in the presence of anions, which locate between and at the periphery of the rings, novel strongly bent H-bonds are also present. Primary (ring; C-H···Cl(-)) H-bonds and anion-π(+) (C(2)···Cl(-)) interactions are found to decay more rapidly with distance than secondary (aliphatic; C(M)-H···Cl(-)) H-bonds. This leads to an increase in the relative importance of secondary H-bond interactions in the IP-dimers. Moreover, rotation of the methyl groups within the "stacked" π(+)-π(+) IP-dimers facilitates the formation of (stronger) linear secondary H-bonds. Thus, compared to isolated IPs, secondary H-bonds may play an increased role within the condensed phase. Overall we find that structural fluidity is facilitated by fluctuating hydrogen bond, π(+)-π(+) and anion-π(+) interactions.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Hydrogen bonding and π–π interactions in imidazolium-chloride ionic liquid clusters

Matthews

Welton

Hunt

2015

Phys. Chem. Chem. Phys.

114

150

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“…[7][8][9][10][11][12] Although, on one hand, ideality makes the tuning of the properties of IL mixtures easier,n ovel properties are difficult to achieve, as the characteristics change between the extremes of the pure components. However,c onsidering (especially local) microscopic structures, [13,14] deviations from ideality can be detected. This has been confirmed by opticalK err effect spectroscopy [15] and theoretically by classical [16] and ab initio [13,14] molecular dynamics (MD) simulations.…”

Section: Introductionmentioning

confidence: 99%

“…However,c onsidering (especially local) microscopic structures, [13,14] deviations from ideality can be detected. This has been confirmed by opticalK err effect spectroscopy [15] and theoretically by classical [16] and ab initio [13,14] molecular dynamics (MD) simulations. Furthermore, the non-ideal mixingb ehavior of hydrogen bonding in mixtures of protic ILs has been studied by far-IR spectroscopy measurements supported by MD simulations by the Ludwig group.…”

Section: Introductionmentioning

confidence: 99%

Triphilic Ionic‐Liquid Mixtures: Fluorinated and Non‐fluorinated Aprotic Ionic‐Liquid Mixtures

et al. 2015

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We present here the possibility of forming triphilic mixtures from alkyl- and fluoroalkylimidazolium ionic liquids, thus, macroscopically homogeneous mixtures for which instead of the often observed two domains—polar and nonpolar—three stable microphases are present: polar, lipophilic, and fluorous ones. The fluorinated side chains of the cations indeed self-associate and form domains that are segregated from those of the polar and alkyl domains. To enable miscibility, despite the generally preferred macroscopic separation between fluorous and alkyl moieties, the importance of strong hydrogen bonding is shown. As the long-range structure in the alkyl and fluoroalkyl domains is dependent on the composition of the liquid, we propose that the heterogeneous, triphilic structure can be easily tuned by the molar ratio of the components. We believe that further development may allow the design of switchable, smart liquids that change their properties in a predictable way according to their composition or even their environment.

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“…EAN is a structurally heterogeneous and bicontinuous PIL, with polar domains, constituted of nitrate anion and ammonium groups, and apolar domains, constituted of methylene and methyl groups. The packing into an ordered liquid is provided by the solvophobic, electrostatic and strong hydrogen bonding interactions [21,22] as for other pure ILs [23][24][25][26][27][28][29][30][31][32][33][34][35][36][37][38] . The melting point is at 286 K [39,40] .…”

Section: Introductionmentioning

confidence: 99%

Mapping the Free Energy of Lithium Solvation in the Protic Ionic Liquid Ethylammonuim Nitrate: A Metadynamics Study

et al. 2017

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The understanding of lithium solvation and transport in ionic liquids is important due to the possible applications in electrochemical devices. Using first principles simulations aided with the metadynamics approach we study the free energy landscape for lithium at infinite dilution conditions in ethylammonium nitrate, a protic ionic liquid. We analyze the local structure of the liquid around the lithium cation and find a quantitative picture in agreement with experimental findings. Our simulations show that the lowest two free energy minima correspond to conformations with the lithium solvated either by 3 or 4 nitrates ions with a transition barrier between them of 0.2 eV. Other less probable conformations having a different solvation pattern are also investigated.1

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On the ideality of binary mixtures of ionic liquids

Cited by 91 publications

References 51 publications

Hydrogen bonding and π–π interactions in imidazolium-chloride ionic liquid clusters

Hydrogen bonding and π–π interactions in imidazolium-chloride ionic liquid clusters

Triphilic Ionic‐Liquid Mixtures: Fluorinated and Non‐fluorinated Aprotic Ionic‐Liquid Mixtures

Mapping the Free Energy of Lithium Solvation in the Protic Ionic Liquid Ethylammonuim Nitrate: A Metadynamics Study

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