Magnetic ionic liquids in analytical chemistry: A review

Data for the transport properties electrical conductivity, κ, and dynamic viscosity, η, of the imidazolium ionic liquids [Emim][FAP], [Emim][Ac], [Bmim][BETI], [Bmim][FSI], [Hmim][TFSI], and [Omim][TFSI] (κ only) is presented. Electrical conductivity has been studied in the wide temperature range of (273.15 to 468.15) K, whereas η was determined in the range of (273.15 to 408.15) K. The data could be well fitted by the empirical Vogel–Fulcher–Tammann equation. Additionally, the densities of these ionic liquids, showing a linear dependence on temperature, were collected from (273.15 to 363.15) K.

Densities, Viscosities, and Conductivities of the Imidazolium Ionic Liquids [Emim][Ac], [Emim][FAP], [Bmim][BETI], [Bmim][FSI], [Hmim][TFSI], and [Omim][TFSI]

Room temperature ionic liquids (RTILs) melt below 100 oC and in this book only commonly available, i.e., aprotic ones, are dealt with, but the properties of two atypical protic ones are shown. The structural aspects of RTILs as derived from diffraction studies and computer simulations, and the modelling of the properties of RTILs are dealt with. The thermochemical data that are tabulated include the melting and decomposition temperatures, the vaporization, cohesive energies and solubility parameters, the critical properties, heat capacities, and surface tension. Also dealt with are the volumetric properties, including the compressibilities and internal pressures. The refractive index and static permittivity are listed. The tabulated and discussed transport properties include the viscosity and electrical and thermal conductivities. The chemical properties that are discussed and listed comprise the solvatochromic parameters, the mutual solubility with water, the hydrophilic/hydrophobic balance, and the solubility of carbon dioxide in the RTILs.

Room Temperature Ionic Liquids

The second part of this compendium concludes with a collection of phase change enthalpies of organic molecules inclusive of C11–C192 reported over the period 1880–2015. Also included are phase change enthalpies including fusion, vaporization, and sublimation enthalpies for organometallic, ionic liquids, and a few inorganic compounds. Paper I of this compendium, published separately, includes organic compounds from C1 to C10 and describes a group additivity method for evaluating solid, liquid, and gas phase heat capacities as well as temperature adjustments of phase changes. Paper II of this compendium also includes an updated version of a group additivity method for evaluating total phase change entropies which together with the fusion temperature can be useful in estimating total phase change enthalpies. Other uses include application in identifying potential substances that either form liquid or plastic crystals or exhibit additional phase changes such as undetected solid–solid transitions or behave ani...

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Phase Transition Enthalpy Measurements of Organic and Organometallic Compounds and Ionic Liquids. Sublimation, Vaporization, and Fusion Enthalpies from 1880 to 2015. Part 2. C11–C192

Quantitative prediction of physical properties of room temperature ionic liquids through nonpolarizable force field based molecular dynamics simulations is a challenging task The challenge lies in the fact that mean ion charges in the condensed phase can be less than unity due to polarization and charge transfer effects whose magnitude cannot be fully captured through quantum chemical calculations conducted in the gas phase The present work employed the density-derived electrostatic and chemical (DDEC/c3) charge partitioning method to calculate site charges of ions using electronic charge densities obtained from periodic density functional theory (DFT) calculations of their crystalline phases The total ion charges obtained thus range between -06e for chloride and -08e for the PF6 ion The mean value of the ion charges obtained from DFT calculations of an ionic liquid closely matches that obtained from the corresponding crystal thus confirming the suitability of using crystal site charges in simulations of liquids These partial charges were deployed within the well-established force field developed by Lopes et al, and consequently, parameters of its nonbonded and torsional interactions were refined to ensure that they reproduced quantum potential energy scans for ion pairs in the gas phase The refined force field was employed in simulations of seven ionic liquids with six different anions Nearly quantitative agreement with experimental measurements was obtained for the density, surface tension, enthalpy of vaporization, and ion diffusion coefficients

Quantitative prediction of physical properties of imidazolium based room temperature ionic liquids through determination of condensed phase site charges: a refined force field.

The values of density, surface tension, and refractive index were measured for a classic series of air and water stable ionic liquids (ILs) based on tetrafluoroborate, [Cnmim][BF4](n = 2,3,4,5,6)(1-alkyl-3-methylimidazolium tetrafluoroborate) in the temperature range of (298.15 to 338.15 ± 0.02) K. In terms of Glasser’s theory, the standard molar entropy and lattice energy of the ILs were calculated. Using Kabo’s method, the molar enthalpy of vaporization of the IL, ΔlgHm0 (298 K), was estimated. According to the interstice model, the thermal expansion coefficient of ILs [Cnmim][BF4] (n = 2,3,4,5,6), α, were calculated, and in comparison with experimental value, their magnitude order is in good agreement. To test this new concept of ionic parachor, [BF4]− was chosen as a reference ion and its individual value of ionic parachor was determined in terms of extrathermodynamic assumption. Then, using ionic parachor of [BF4]−, the ionic parachors for all corresponding imidazolium cations, [Cnmim]+, were calcula...

Density, Surface Tension, and Refractive Index of Ionic Liquids Homologue of 1-Alkyl-3-methylimidazolium Tetrafluoroborate [Cnmim][BF4] (n = 2,3,4,5,6)

Five acetate-based ionic liquids (AcAILs) [Cnmim][OAc](n = 2, 3, 4, 5, 6) (1-alkyl-3-methylimidazolium acetate) were prepared by the neutralization method and characterized by 1H NMR spectroscopy and differential scanning calorimetry (DSC). Their density, surface tension, and refractive index were measured at 298.15 to 338.15 K. Since the AcAILs can form strong hydrogen bonds with water, small amounts of water are difficult to remove by common methods. In order to eliminate the effect of the impurity water, the standard addition method (SAM) was applied to these measurements. On the basis of the experimental data, the molecular volume (sum of positive and negative ion volumes), Vm, of [Cnmim][OAc](n = 2, 3, 4, 5, 6), the entropy of surface formation, Sa, the Gibbs energy of surface formation Ea, the parachor, P, and the molar refraction, Rm, the polarization coefficient, αp, were calculated. The results show that Ea, P, and Rm are approximately temperature-independent and the contribution to these propert...

Prediction of Thermophysical Properties of Acetate-Based Ionic Liquids Using Semiempirical Methods

Two new lanthanide-based room temperature ionic liquids [Bmim][Ln(NO3)4] (Bmim = 1-butyl-3-methylimidazolium; Ln = Dy, Sm) were synthesized and characterized. They show good luminescent properties and could be used as good soft luminescent materials. These kinds of hydrostable and eco-friendly ionic liquids were first used to explore the sensing behavior for Fe(III) ions, exhibit a highly specific recognition, and are not interfered by the following common mental ions: Ca(II), Al(III), Zn(II), Cu(II), Pb(II), Hg(II), Cd(II), Co(II), Fe(II), Ni(II), and Cr(III). These lanthanide-based ionic liquids with strong luminescence have an outstanding application prospect in “green” fluorescent sensor and can be widely used in actual detection of Fe(III) in aqueous solutions.

Synthesis of Lanthanide-Based Room Temperature Ionic Liquids with Strong Luminescence and Selective Sensing of Fe(III) over Mixed Metal Ions

Study on Enthalpy and Molar Heat Capacity of Solution for the Ionic Liquid [C2mim][OAc] (1-Ethyl-3-methylimidazolium acetate)

Two bis(trifluoromethyl sulfonyl)imide ionic liquids [Cnmmim][NTf2] (n = 2, 4) {1-alkyl-2,3-dimethyimidazolium-N,N-bis(trifluoromethyl sulfonyl)imide} were prepared and characterized by 1H NMR spectroscopy and differential scanning calorimetry (DSC). The values of their density, surface tension and refractive index were measured in the temperature range of (298.15 to 338.15 ± 0.01) K and the average contributions to the density, surface tension, and refractive index per methyl group in the alkyl chain and the addition of a methylene group in the imidazolium ring for the ILs were discussed. The dependence of volumetric properties, surface properties and molar refraction on temperature was discussed. Based on Kabo's method and Verevkin's experimental values, the molar enthalpies of vaporization, ΔHv, for [Cnmmim][NTf2] (n = 2, 4) were estimated. As a new idea, it was put forward that ΔHv can be assumed to consist of two parts: a part corresponds with the induced energy, ΔHvn, and another part corresponds with orientation energy from the permanent dipole moment of the ion pair in ILs, ΔHvμ. The values of ΔHvn were calculated in terms of the Lawson–Ingham equation so that the values of ΔHvμ could be estimated. Using the values of ΔHv, ΔHvn and ΔHvμ, cohesive energy density, δ2 (δ is Hildebrand solubility parameter), the contribution of induced energy, δn2, and the contribution of orientation energy, δμ2, were obtained. If a liquid only has δn then it is a non-polar liquid and if a liquid not only has δn, but also has δμ then it is a polar liquid. Since the ion pairs in ILs have a permanent dipole moment, the ionic liquid has a certain polarity. Therefore, using δμ as the polarity scaling of ILs is very convenient because the values of δμ are very easy to calculate from the enthalpy of vaporization and refractive index data.

Jie Wei

Papers

Density, Surface Tension, and Refractive Index of Ionic Liquids Homologue of 1-Alkyl-3-methylimidazolium Tetrafluoroborate [Cnmim][BF4] (n = 2,3,4,5,6)

Prediction of Thermophysical Properties of Acetate-Based Ionic Liquids Using Semiempirical Methods

Synthesis of Lanthanide-Based Room Temperature Ionic Liquids with Strong Luminescence and Selective Sensing of Fe(III) over Mixed Metal Ions

Study on Enthalpy and Molar Heat Capacity of Solution for the Ionic Liquid [C2mim][OAc] (1-Ethyl-3-methylimidazolium acetate)

Study on thermodynamic properties and estimation of polarity of ionic liquids {[Cnmmim][NTf2] (n = 2, 4)}