Using microwave-assisted synthesis method, a series of paramagnetic ionic liquids comprising 1-vinyl-3-alkylimidazolium VRIM + cation and tetrahalogenidoferrate (III) FeCl m Br 4 À m À anion were designed and synthesized. The structure was analyzed using 1 H NMR and Raman spectroscopy. Ultraviolet-visible absorption spectra, thermal stability, magnetic susceptibility, viscosity, ionic conductivity, and solubility were characterized. Results show that elongation of the alkyl chain leads to replacement of bromides with a small amount of chlorides in the anion, shifting of UV maximum absorption peaks to shorter wavelengths, reduction of ionic conductivity, and solubility in polar solvents, as well as increase in fluidity, magnetic susceptibility, and solubility in nonpolar solvents.
A series of 1-vinyl-3-alkylimidazolium halide ([VRIM]X) and 1-vinyl-3-esterimidazolium chloride ([VEIM]-Cl) ionic liquids, a functional material with unsaturated bonds, were synthesized by using microwave-assisted synthesis method. The structures were characterized by 1 H NMR. Through Gaussian09/B3PW91/6-311G (2d,p) density functional methods, the interaction energies of ion pairs of [VRIM]X and [VEIM]Cl were obtained. The relationships between the surface tensions and temperature (293.15 to 333.15) K, molecular structure, and the interaction energies of ion pairs, etc. along with the relationships between the solubility and molecular structure, common solvents, and the interaction energies of ion pairs, etc. were discussed systematically. The results showed that surface tension decreased linearly with temperature and decreased with the elongation of the alkyl chain length on cation and the decrease of interaction energies of ion pairs. With decreasing dielectric constant of solvent or the increase of the anion size, the solubility of the title ionic liquids decreased. With the elongation of the alkyl chain length, the interaction energies of ion pairs decreased, and the solubility in polar solvents had decreasing trend. The relationship between the surface tensions and solubility parameter for [VRIM]Br was expressed by using Hildebrand−Scoff equation. ■ INTRODUCTIONIonic liquids (ILs) are organic salts at room temperature or less than 300°C which are entirely composed of an organic cation (imidazolium, pyridinium, tetraalkylammonium, etc.) and an anion such as halide, triflate, amidotriflate, dicyanamide, tetrafluoroborate, hexafluorophosphate, etc. 1 The ionic character implies the extraordinary high ion density, and thus leads to the negligible vapor pressure (i.e, wide liquid temperature range and negligible flammability) and high ionic conductivity. 2,3 A key feature of ILs is that their physicochemical properties can be tailored virtually at will by varying their cations, substituents, and anions. 4−6 Research on structure and properties of ILs are mainly focused on melting point, conductivity, density, thermal stability, etc. at present, 7−17 which provide some theoretical basis for the structure analysis of ILs, the design and synthesis of novel functionalized ILs. 18,19 In addition, ILs have better solubility and surface activity; thus, they have been widely used in many scientific fields. 20−27 However, studies on the surface tension and solubility of ILs are still scarce, and the surface tensions of only a few of ILs have been reported; 28−32 Previous studies mainly have been done on the qualitative analysis of the solubility of ILs in organic or inorganic solvents, with little attention paid to the quantitative analysis of their solubility and the general law of solubility; The surface tension and solubility for most common ILs mainly concentrates on several N-alkyl-N-methylimidazolium ILs. 33−37 None of these studies have investigated the surface tension and the quantitative analysis of the solubil...
To solve the problems associated with poorly water-soluble nonsteroidal anti-inflammatory drugs (NSAIDs), naproxen-based ionic liquids (ILs) containing naproxen as an active pharmaceutical ingredient (API) anion were prepared with benzalkonium (tetradecyldimethylbenzyl ammonium), choline, and 1-octyl-3-methylimidazole as the cation. The structures and thermal properties were analyzed. Through the conductivity method, the solubility at 25 and 37 °C and the critical micelle concentration (CMC) at 25 °C were determined in water and ethanol. The octanol−water partition coefficients (K ow ) at 25 °C were measured with the shake-flask method. The cytotoxicity was evaluated with the MTT method. The results showed that the conversion of naproxen into the API-ILs increased the API's solubility in water by more than 850 times compared with the original API, and the thermostability was satisfactory with a lower glass transition temperature (t g ). Moreover, the variation trends of solubility, hydrophilicity, and K ow were consistent with the different structures of naproxen-based ILs, except for benzalkonium naproxen. The CMC (10 −5 −10 −6 M) in water and ethanol demonstrated that the naproxen-based ILs were surface activite ILs. The IC 50 values exhibited the low cytotoxicity of the naproxen-based ILs, which was better than 100 μM. The results provide essential information and a research basis for future topical and transdermal administration and oral administration of naproxen-based ILs.
N-Vinyl-3-alkylimidazolium tetrahalogenidoferrate(III) ([VRIM][FeX4], X4 = Cl3Br, Cl4) and N-vinyl-3-esterimidazolium tetrachloroferrate(III)([VEIM][FeCl4]) magnetic ionic liquids were synthesized. They were characterized by 1H NMR, Raman, electrospray ionization mass spectrometry, differential scanning calorimetry and thermogravimetric analysis. Through Gaussian09/B3LYP/LANL2DZ density functional theory, the interaction energies of ion pairs and dipole moment of [VRIM][FeX4] and [VEIM][FeCl4] were obtained. The relationships between the surface tensions and temperature, molecular structure, and interaction energies of ion pairs along with the relationships between the solubility and molecular structure, common solvents, and interaction energies of ion pairs were discussed systematically. The relationship between the surface tensions and solubility parameter for [VRIM][FeX4] was expressed by using a Hildebrand–Scoff equation. And the hydrophilic–lipophilic balance (HLB) values of [VRIM][FeX4] were obtained by a solubility parameter. The results showed that surface tension decreased linearly with temperature and decreased with the elongation of alkyl chain length on cation and the decrease of interaction energies of ion pairs; With decreasing dielectric constant of solvent, the solubility of the title magnetic ionic liquids increased first and then decreased; with the elongation of alkyl chain length, the interaction energies of ion pairs and HLB value decreased, and the solubility in polar solvents had a decreasing trend.
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