Pyrazolium- versus Imidazolium-Based Ionic Liquids: Structure, Dynamics and Physicochemical Properties

Chiappe, Cinzia; Sanzone, Angelo; Mendola, Daniele; Castiglione, Francesca; Famulari, Antonino; Raos, Guido

doi:10.1021/jp3107793

Cited by 54 publications

(35 citation statements)

References 44 publications

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“…69 Fig. 4(a) shows that the 2005 74 are generally 9 to 24 % higher than ours, with only the datum for the anion at 25 o C in good agreement; the results of Chiappe et al 75 at 32 o C are some 25% higher than those of this work. For [HMIM][Tf 2 N], the result of Ahosseini et al 56 for the cation at 25 o C agrees fairly well, but that at 50 o C is 14% higher that of this work.…”

Section: Resultssupporting

confidence: 57%

Self-diffusion, velocity cross-correlation, distinct diffusion and resistance coefficients of the ionic liquid [BMIM][Tf₂N] at high pressure

Harris

Kanakubo

2015

Phys. Chem. Chem. Phys.

142

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Ion self-diffusion coefficients (DSi) have been measured for the ionic liquid 1-butyl-3-methylimidazolium bis(trifluoromethanesulfonyl)amide [BMIM][Tf2N] at pressures to 200 MPa between 25 and 75 °C and at 0.1 MPa between 10 and 90 °C. Self-diffusion coefficients are reported for 1-ethyl-, 1-hexyl- and 1-octyl-3-methylimidazolium bis(trifluoromethanesulfonyl)amide salts at 0.1 MPa, supplemented by viscosity, electrical conductivity and density measurements. Velocity cross-correlation (VCC, fij) and distinct diffusion coefficients (D) are calculated from the data. Both DSi and D are analysed in terms of (fractional) Stokes-Einstein-Sutherland (SES) equations. SES and Walden plots show almost identical slopes, with high-pressure isotherms and the atmospheric pressure isobar falling on common, single lines for each property for [BMIM][Tf2N]. SES plots for the anion self-diffusion coefficients for the [RMIM][Tf2N] (R = alkyl) series are coincident, whereas those for the cations depend on their alkyl substitution, as do the Walden plots. In common with other [Tf2N](-) salts, the VCC follow the order f-- < f++ < f+-. The Nernst-Einstein deviation parameter Δ for [BMIM][Tf2N] is independent of temperature and pressure. Those for the other [Tf2N](-) salts are independent of temperature. Δ increases in magnitude with increasing alkyl chain length on the cation. The transport properties of [BMIM][Tf2N] are re-examined in terms of density scaling using reduced conductivities and reduced molar conductivities for the first time. Identical scaling parameters (γ) are obtained for the several reduced transport properties. This result is supported by data for other ionic liquids. It is suggested that the γ for ionic liquids may depend on packing fraction.

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Section: Resultssupporting

confidence: 57%

Self-diffusion, velocity cross-correlation, distinct diffusion and resistance coefficients of the ionic liquid [BMIM][Tf₂N] at high pressure

Harris

Kanakubo

2015

Phys. Chem. Chem. Phys.

142

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“…One reason to give this latter possibility serious consideration is the fact that the HOESY spectra for these ILs show negligible interactions between these same cationic protons and the fluorine nuclei of the NTf 2 − anions. 71,72,78 The ROESY spectra of the solutions with pyrrolidiniumcation ILs suggest that the alkyl tail of Pyrr 10,1 + interacts strongly with the bpy ligands on the Ru 2+ (bpy) 3 solute. In contrast, all of the protons on the Pyrr 4,1 + cation show signficant interactions with all four of the bpy protons of Ru 2+ (bpy) 3 .…”

Section: ■ Results and Discussionmentioning

confidence: 99%

“…66 71,72,76,78 The four different ILs used in these experiments include two aromatic imidazolium and two nonaromatic pyrrolidinium cations, with each cation paired with the bis(trifluoromethylsulfonyl)amide (NTf 2 − ) anion. Longer alkyl tails on either cations or anions lead to the formation of nanometer scale hydrophobic domains that alternate with polar domains.…”

Section: ■ Introductionmentioning

confidence: 99%

Ionic Liquid–Solute Interactions Studied by 2D NOE NMR Spectroscopy

Khatun

Castner

2014

J. Phys. Chem. B

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Intermolecular interactions between a Ru(2+)(bpy)3 solute and the anions and cations of four different ionic liquids (ILs) are investigated by 2D NMR nuclear Overhauser effect (NOE) techniques, including {(1)H-(19)F} HOESY and {(1)H-(1)H} ROESY. Four ILs are studied, each having the same bis(trifluoromethylsulfonyl)amide anion in common. Two of the ILs have aliphatic 1-alkyl-1-methylpyrrolidinium cations, while the other two ILs have aromatic 1-alkyl-3-methylimidazolium cations. ILs with both shorter (butyl) and longer (octyl or decyl) cationic alkyl substituents are studied. NOE NMR results suggest that the local environment of IL anions and cations near the Ru(2+)(bpy)3 solute is rather different from the bulk IL structure. The solute-anion and solute-cation interactions are significantly different both for ILs with short vs long alkyl tails and for ILs with aliphatic vs aromatic cation polar head groups. In particular, the solute-anion interactions are observed to be about 3 times stronger for the cations with shorter alkyl tails relative to the ILs with longer alkyl tails. The Ru(2+)(bpy)3 solute interacts with both the polar head and the nonpolar tail groups of the 1-butyl-1-methylpyrrolidinium cation but only with the nonpolar tail groups of the 1-decyl-1-methylpyrrolidinium cation.

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“…13,15,17,[22][23][24][25][26][27][28][29][30][31][32][33][34][35][36][37][38][39][40][47][48][49][50][51] It should be highlighted that the hydrogen-bond acceptor strength of an IL is dominated by its anion while the hydrogen-bond donor ability is essentially controlled by the cation and only slightly depends upon the anion of the IL. 18,19 Thus, and since we were focused on developing an extended series for the hydrogen-bond acidity of ILs, ILs comprising a fixed anion ([NTf 2 ] − ) and a wide range of cations (imidazolium-, pyridinium-, piperidinium-, pyrrolidinium-, ammonium-, sulfonium-, and phosphonium-based) were selected.…”

Section: Introductionmentioning

confidence: 99%

Hydrogen-bond acidity of ionic liquids: an extended scale

Kurnia

Lima

Cláudio

et al. 2015

Phys. Chem. Chem. Phys.

102

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One of the main drawbacks comprising an appropriate selection of ionic liquids (ILs) for a target application is related to the lack of an extended and well-established polarity scale for these neoteric fluids. Albeit considerable progress has been made on identifying chemical structures and factors that influence the polarity of ILs, there still exists a high inconsistency in the experimental values reported by different authors. Furthermore, due to the extremely large number of possible ILs that can be synthesized, the experimental characterization of their polarity is a major limitation when envisaging the choice of an IL with a desired polarity. Therefore, it is of crucial relevance to develop correlation schemes and a priori predictive methods able to forecast the polarity of new (or not yet synthesized) fluids. In this context, and aiming at broadening the experimental polarity scale available for ILs, the solvatochromic Kamlet-Taft parameters of a broad range of bis(trifluoromethylsulfonyl)imide-([NTf 2 ] − )-based fluids were determined. The impact of the IL cation structure on the hydrogen-bond donating ability of the fluid was comprehensively addressed. Based on the large amount of novel experimental values obtained, we then evaluated COSMO-RS, COnductor-like Screening MOdel for Real Solvents, as an alternative tool to estimate the hydrogen-bond acidity of ILs. A three-parameter model based on the cation-anion interaction energies was found to adequately describe the experimental hydrogen-bond acidity or hydrogen-bond donating ability of ILs. The proposed three-parameter model is also shown to present a predictive capacity and to provide novel molecular-level insights into the chemical structure characteristics that influence the acidity of a given IL. It is shown that although the equimolar cation-anion hydrogen-bonding energies (E HB ) play the major role, the electrostaticmisfit interactions (E MF ) and van der Waals forces (E vdW ) also contribute, admittedly in a lower extent, towards the hydrogen-bond acidity of ILs. The new extended scale provided for the hydrogen-bond acidity of ILs is of high value for the design of new ILs for task-specific applications. † Electronic supplementary information (ESI) available: Comparison between experimental and literature solvatochromic values; correlation between experimental and predicted hydrogen-bond acidity; equation to calculate the absolute relative deviation. See

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Pyrazolium- versus Imidazolium-Based Ionic Liquids: Structure, Dynamics and Physicochemical Properties

Cited by 54 publications

References 44 publications

Self-diffusion, velocity cross-correlation, distinct diffusion and resistance coefficients of the ionic liquid [BMIM][Tf₂N] at high pressure

Self-diffusion, velocity cross-correlation, distinct diffusion and resistance coefficients of the ionic liquid [BMIM][Tf₂N] at high pressure

Ionic Liquid–Solute Interactions Studied by 2D NOE NMR Spectroscopy

Hydrogen-bond acidity of ionic liquids: an extended scale

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Pyrazolium- versus Imidazolium-Based Ionic Liquids: Structure, Dynamics and Physicochemical Properties

Cited by 54 publications

References 44 publications

Self-diffusion, velocity cross-correlation, distinct diffusion and resistance coefficients of the ionic liquid [BMIM][Tf2N] at high pressure

Self-diffusion, velocity cross-correlation, distinct diffusion and resistance coefficients of the ionic liquid [BMIM][Tf2N] at high pressure

Ionic Liquid–Solute Interactions Studied by 2D NOE NMR Spectroscopy

Hydrogen-bond acidity of ionic liquids: an extended scale

Contact Info

Product

Resources

About

Self-diffusion, velocity cross-correlation, distinct diffusion and resistance coefficients of the ionic liquid [BMIM][Tf₂N] at high pressure

Self-diffusion, velocity cross-correlation, distinct diffusion and resistance coefficients of the ionic liquid [BMIM][Tf₂N] at high pressure