Properties of Water Confined in Ionic Liquids

Saihara, Koji; Yoshimura, Yukihiro; Ohta, Shinichiro; Shimizu, Akio

doi:10.1038/srep10619

Cited by 78 publications

(85 citation statements)

References 34 publications

(37 reference statements)

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“…Additional outcomes of simulations also indicated the change of interactions between IL species and solvent molecules for low mole fractions of ILs 39 . In agreement with numerical findings, recent experimental results also highlighted an order of magnitude larger diffusivity of water molecules in comparison to the IL ions 40,41 .…”

Section: Introductionsupporting

confidence: 77%

The properties of residual water molecules in ionic liquids: a comparison between direct and inverse Kirkwood–Buff approaches

Kobayashi

Reid

Shimizu

et al. 2017

Phys. Chem. Chem. Phys.

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We study the properties of residual water molecules at different mole fractions in dialkylimidazolium based ionic liquids (ILs), namely 1-ethyl-3-methylimidazolium tetrafluoroborate (EMIM/BF4) and 1-butyl-3-methylimidazolium tetrafluoroborate (BMIM/BF4) by means of atomistic molecular dynamics (MD) simulations. The corresponding Kirkwood-Buff (KB) integrals for the water-ion and ion-ion correlation behavior are calculated by a direct evaluation of the radial distribution functions. The outcomes are compared to the corresponding KB integrals derived by an inverse approach based on experimental data. Our results reveal a quantitative agreement between both approaches, which paves a way towards a more reliable comparison between simulation and experimental results. The simulation outcomes further highlight that water even at intermediate mole fractions has a negligible influence on the ion distribution in the solution. More detailed analysis on the local/bulk partition coefficients and the partial structure factors reveal that water molecules at low mole fractions mainly remain in the monomeric state. A non-linear increase of higher order water clusters can be found at larger water concentrations. For both ILs, a more pronounced water coordination around the cations when compared to the anions can be observed, which points out that the IL cations are mainly responsible for water pairing mechanisms. Our simulations thus provide detailed insights in the properties of dialkylimidazolium based ILs and their effects on water binding.

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Section: Introductionsupporting

confidence: 77%

The properties of residual water molecules in ionic liquids: a comparison between direct and inverse Kirkwood–Buff approaches

Kobayashi

Reid

Shimizu

et al. 2017

Phys. Chem. Chem. Phys.

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“…[12,15] The 13 C-{ 1 H} NMR spectrao fC O 2 dissolved in BMIm·PF 6 ,B MIm·BF 4, and BMIm·NTf 2 with controlled amounts of added water is almosti denticalt ot he dry ILs and almost the same amount of dissolvedC O 2 is attained( see Figures S21, S24, S27, and Ta ble S2). [38,39] The solubility of CO 2 in imidazolium-based ILs associated with acetate anion was already investigated in detail. In fact, NMR diffusion studies suggest the formation of nanostructures with water and ions diffusing in differentd omains.…”

Section: Resultsmentioning

confidence: 99%

Carbon Dioxide Capture by Aqueous Ionic Liquid Solutions

et al. 2017

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Confined water in aqueous solutions of imidazolium-based ionic liquids (ILs) associated with acetate and imidazolate anions react reversibly with CO to yield bicarbonate. Three types of CO sorption in these "IL aqueous solutions" were observed: physical, CO -imidazolium adduct generation, and bicarbonate formation (up to 1.9 mol mol of IL), resulting in a 10:1 (molar ratio) total absorption of CO relative to imidazolate anions in the presence of water 1:1000 (IL/water). These sorption values are higher than the classical alkanol amines or even alkaline aqueous solutions under similar experimental conditions.

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“…This leads to the disruption of some cation/anion interactions increasing both the rotational and translational dynamics of the anion. This is in accordance with the observation of Saihara et al that also described the existence of water pockets inside the IL framework to explain the observation of two water species HOD and H 2 O in exchange in the water‐pocked sited nano‐IL domain structure.…”

Section: Discussionmentioning

confidence: 99%

Ion pair and solvation dynamics of [Bmim][BF₄] + water system

Cascão

Silva

Ferreira

et al. 2017

Magnetic Reson in Chemistry

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In this work, 1-butyl-3-methylimidazolium tetrafluoroborate/water mixtures were analysed over the whole water composition (x ) in order to study the rotational and translational behaviour of the ions. We employed a multinuclear NMR approach to determine anion/cation/water diffusion coefficients and longitudinal relaxation rates at different water content. In neat ionic liquids (IL), the cation diffuses faster than the anion, and at low x , anions and cations share almost the same diffusion coefficient, but above a critical water concentration, the anion begins to diffuse faster than the cation. We identified this composition as approximately 10% x where the ions share the same diffusion coefficient. We found that the water at this composition seems to have a much more dramatic effect in the rotational diffusion of the anion that decreases substantially and approaches that of the anion in the diluted IL. Translational and rotational dynamics of the ions suggest that water is first incorporated in pockets in the nanostructure of the IL allowing the ions to maintain most of the cation/anion interactions present in neat IL but already disrupting some anion/cation interactions due to preferential interaction with the anion. HOESY and NOESY data show that water displays contacts both with the cation and the anion in a positive NOE regime in contrary to the negative regime found for the cation/anion and cation/cation cross-relaxation. This is in accordance with the high relative diffusion coefficient of water and suggests that water molecules can exchange between preferential location sites that allow water to maintain contacts both with the anion and cation.

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Properties of Water Confined in Ionic Liquids

Cited by 78 publications

References 34 publications

The properties of residual water molecules in ionic liquids: a comparison between direct and inverse Kirkwood–Buff approaches

The properties of residual water molecules in ionic liquids: a comparison between direct and inverse Kirkwood–Buff approaches

Carbon Dioxide Capture by Aqueous Ionic Liquid Solutions

Ion pair and solvation dynamics of [Bmim][BF₄] + water system

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Properties of Water Confined in Ionic Liquids

Cited by 78 publications

References 34 publications

The properties of residual water molecules in ionic liquids: a comparison between direct and inverse Kirkwood–Buff approaches

The properties of residual water molecules in ionic liquids: a comparison between direct and inverse Kirkwood–Buff approaches

Carbon Dioxide Capture by Aqueous Ionic Liquid Solutions

Ion pair and solvation dynamics of [Bmim][BF4] + water system

Contact Info

Product

Resources

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Ion pair and solvation dynamics of [Bmim][BF₄] + water system