Aggregation behaviour of chiral ionic liquids

Schulz, Peter S.; Schneiders, Karola; Wasserscheid, Peter

doi:10.1016/j.tetasy.2009.10.010

Cited by 17 publications

(7 citation statements)

References 32 publications

(17 reference statements)

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“…The Stokes–Einstein equation with c = 6 is based on the model of a sphere moving through a viscous medium. The viscosity of DMSO is comparably low, and deviations from the stick boundary conditions can be expected. , Additional considerations such as the relative size of solute to solvent and shape of diffusing particle would also need be considered for determining accurate radii as recently thoroughly reviewed by Macchioni et al In this regard, we like to point out that the [NTf 2 ] − anion can undergo conformational changes along the CSNS dihedral angle, , and Tsuzuki et al report significant decreases in self-diffusion coefficients if the torsional angles are constrained . To account for the relative size of solute radius r and solvent radius r solv , Chen and Chen used eq to evaluate c , which they derived from the microfriction theory by Gierer and Wirtz …”

Section: Resultsmentioning

confidence: 99%

Ion Pairing and Dynamics of the Ionic Liquid 1-Hexyl-3-methylimidazolium Bis(irifluoromethylsulfonyl)amide ([C₆mim][NTf₂]) in the Low Dielectric Solvent Chloroform

2012

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The structural and dynamic behavior of the ionic liquid 1-hexyl-3-methylimidazolium bis(trifluoromethylsulfonyl)amide ([C(6)mim][NTf(2)]) in chloroform has been studied by experimental measurements of (1)H and (19)F self-diffusion coefficients, viscosity, and excess molar volume in the concentration range of 0.001-1.0 mol·kg(-1) and temperatures ranging from 15 to 45 °C. Within measurement uncertainty, the (1)H and (19)F self-diffusion coefficients are identical at the same experimental conditions of concentration and temperature, indicating that even to the lowest measured concentrations the cation and anion are not completely dissociated. The combined experimental data indicates a progression from ion pairing to aggregate formation as concentration increases where at concentrations near 0.1 mol·kg(-1) aggregate formation becomes dominant. Concurrently with the formation of the IL aggregates at higher concentrations, we also observe an apparent breakdown of the validity of the Stokes-Einstein equation, which we explain by translational motion to become dominated by individual ion pairs moving rapidly between IL aggregates.

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Section: Resultsmentioning

confidence: 99%

Ion Pairing and Dynamics of the Ionic Liquid 1-Hexyl-3-methylimidazolium Bis(irifluoromethylsulfonyl)amide ([C₆mim][NTf₂]) in the Low Dielectric Solvent Chloroform

2012

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“…Wide-angle X-ray scattering observed the aggregation deduced through the intermolecular partial atom–atom correlation function between terminal methyl carbons of the butyl chain in [C 4 pyr][NTf 2 ] IL. Diffusion ordered NMR spectroscopy was used to determine the aggregate number of the diastereomeric (1R,2S)-ephedrinium ( RS )-methoxytrifluorophenylacetate IL. Atmospheric pressure measurements found the microheterogenous structures with polar and nonpolar domains in the 1-butyl-3-methylimidazolium octylsulfate IL.…”

Section: Mesoscale Structures Of Ilsmentioning

confidence: 99%

Multiscale Studies on Ionic Liquids

et al. 2017

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Ionic liquids (ILs) offer a wide range of promising applications because of their much enhanced properties. However, further development of such materials depends on the fundamental understanding of their hierarchical structures and behaviors, which requires multiscale strategies to provide coupling among various length scales. In this review, we first introduce the structures and properties of these typical ILs. Then, we introduce the multiscale modeling methods that have been applied to the ILs, covering from molecular scale (QM/MM), to mesoscale (CG, DPD), to macroscale (CFD for unit scale and thermodynamics COSMO-RS model and environmental assessment GD method for process scale). In the following section, we discuss in some detail their applications to the four scales of ILs, including molecular scale structures, mesoscale aggregates and dynamics, and unit scale reactor design and process design and optimization of typical IL applications. Finally, we address the concluding remarks of multiscale strategies in the understanding and predictive capabilities of ILs. The present review aims to summarize the recent advances in the fundamental and application understanding of ILs.

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“…[20][21][22][23] NMR spectroscopy and its variations have been used by several groups to specify the magnetic resonance structure 24 and to investigate intermolecular interactions, molecular motion as well as diffusion. [25][26][27][28][29][30] The local organization of imidazolium-based RTILs in their liquid state, in solution as well as in their solid state has been studied using a combination of spectroscopic techniques; mainly vibrational and NMR spectroscopy. [31][32][33][34][35][36] The vibrational structures of imidazolium-based ionic liquids and their interpretation have been the subject of many studies, 16,[37][38][39][40][41] -often with the aim of enabling a more rational design.…”

Section: Introductionmentioning

confidence: 99%

The role of the C2 position in interionic interactions of imidazolium based ionic liquids: a vibrational and NMR spectroscopic study

Noack¹,

Schulz

Paape

et al. 2010

Phys. Chem. Chem. Phys.

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288

248

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Methylation of the C2 position of 1,3-dialkylimidazolium based ionic liquids disrupts the predominant hydrogen-bonding interaction between cation and anion leading to unexpected changes of the physicochemical properties. We found the viscosity of 1-ethyl-2,3-dimethylimidazolium bis(trifluoromethylsulfonyl)imide [C(2)C(1)C(1)Im][Tf(2)N], for example, to be about three times higher than that of 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide [C(2)C(1)Im][Tf(2)N]. In order to explain these macroscopic changes upon methylation we investigated the vibrational as well as the magnetic resonance structure of [Tf(2)N](-) salts involving the cations 1-ethyl-3-methylimidazolium [C(2)C(1)Im](+), 1-ethyl-2,3-dimethylimidazolium [C(2)C(1)C(1)Im](+), 1-butyl-3-methylimidazolium [C(4)C(1)Im](+), and 1-butyl-2,3-dimethylimidazolium [C(4)C(1)C(1)Im](+) by means of Fourier-transform infrared (FTIR), Raman and (13)C NMR as well as (1)H NMR spectroscopy aiming a better microscopic understanding of the cation-anion interaction. To reveal the impact of methylating the C2 position and changing the alkyl side chain length of the imidazolium a detailed assignment of the individual peaks is followed by a comparative discussion of the spectral features also considering already published work. Our spectroscopic findings deduce electron density changes leading to changes in the position and strength of interionic interactions and reduced configurational variations. Both facts are represented on a macroscopic level by the viscosity and melting point. Therefore changes on a macroscopic level clearly express molecular alterations which in turn can be observed using spectroscopic methods as Raman, IR and NMR.

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Aggregation behaviour of chiral ionic liquids

Cited by 17 publications

References 32 publications

Ion Pairing and Dynamics of the Ionic Liquid 1-Hexyl-3-methylimidazolium Bis(irifluoromethylsulfonyl)amide ([C₆mim][NTf₂]) in the Low Dielectric Solvent Chloroform

Ion Pairing and Dynamics of the Ionic Liquid 1-Hexyl-3-methylimidazolium Bis(irifluoromethylsulfonyl)amide ([C₆mim][NTf₂]) in the Low Dielectric Solvent Chloroform

Multiscale Studies on Ionic Liquids

The role of the C2 position in interionic interactions of imidazolium based ionic liquids: a vibrational and NMR spectroscopic study

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Aggregation behaviour of chiral ionic liquids

Cited by 17 publications

References 32 publications

Ion Pairing and Dynamics of the Ionic Liquid 1-Hexyl-3-methylimidazolium Bis(irifluoromethylsulfonyl)amide ([C6mim][NTf2]) in the Low Dielectric Solvent Chloroform

Ion Pairing and Dynamics of the Ionic Liquid 1-Hexyl-3-methylimidazolium Bis(irifluoromethylsulfonyl)amide ([C6mim][NTf2]) in the Low Dielectric Solvent Chloroform

Multiscale Studies on Ionic Liquids

The role of the C2 position in interionic interactions of imidazolium based ionic liquids: a vibrational and NMR spectroscopic study

Contact Info

Product

Resources

About

Ion Pairing and Dynamics of the Ionic Liquid 1-Hexyl-3-methylimidazolium Bis(irifluoromethylsulfonyl)amide ([C₆mim][NTf₂]) in the Low Dielectric Solvent Chloroform

Ion Pairing and Dynamics of the Ionic Liquid 1-Hexyl-3-methylimidazolium Bis(irifluoromethylsulfonyl)amide ([C₆mim][NTf₂]) in the Low Dielectric Solvent Chloroform