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Room-temperature Ionic Liquids (room-temperature + ionic_liquid)

Distribution by Scientific Domains

Chemistry	82%
Polymers and Materials Science	11%

Selected Abstracts

Direct Electrochemistry and Electrocatalysis of Hemoglobin in Lipid Film Incorporated with Room-Temperature Ionic Liquid

ELECTROANALYSIS, Issue 20 2008
Gaiping Li
Abstract A facile phospholipid/room-temperature ionic liquid (RTIL) composite material based on dimyristoylphosphatidylcholine (DMPC) and 1-butyl-3-methylimidazolium hexafluorophosphate ([bmim]PF6) was exploited as a new matrix for immobilizing protein. Cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) were adopted to characterize this composite film. Hemoglobin (Hb) was chosen as a model protein to investigate the composite system. UV-vis absorbance spectra showed that Hb still maintained its heme crevice integrity in this composite film. By virtue of the Hb/DMPC/[bmim]PF6 composite film-modified glassy carbon electrode (GCE), a pair of well-defined redox peaks of Hb was obtained through the direct electron transfer between protein and underlying GCE. Moreover, the reduction of O2 and H2O2 at the Hb/DMPC/[bmim]PF6 composite film-modified GCE was dramatically enhanced. [source]

Ultrasound-Assisted Synthesis of CuO Nanorods in a Neat Room-Temperature Ionic Liquid

EUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 19 2009
Tarek Alammar
Abstract CuO nanorods were prepared via ultrasound-assisted synthesis in the room temperature ionic liquid (RTIL) 1-butyl-3-methylimidazoliumbis(trifluoromethylsulfonyl)imide [C4mim][Tf2N] as a reaction medium. The structure and morphology of CuO nanorods were characterized with X-ray powder diffraction (XRD), transmission electron microscopy (TEM), energy-dispersive X-ray analysis (EDX), X-ray photoelectron spectroscopy (XPS), vibrational and UV/Vis absorption spectroscopy. The synthesized CuO nanocrystals are of rod like shape with lengths from 30 to 100 nm and diameters of about 10 nm. Quantum size effects were observed as the bandgap of the CuO nanorods was determined to 2.41 eV from UV/Vis absorption measurements, which is significantly larger than the bulk value. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009) [source]

Extraction of Lanthanides from Aqueous Solution by Using Room-Temperature Ionic Liquid and Supercritical Carbon Dioxide in Conjunction

CHEMISTRY - A EUROPEAN JOURNAL, Issue 6 2006
Soufiane Mekki Dr.
Abstract For the first time, the study of a three-step extraction system of water/ionic liquid/supercritical CO2 has been performed. Extraction of trivalent lanthanum and europium from an aqueous nitric acid solution to a supercritical CO2 phase via an imidazolium-based ionic liquid phase is demonstrated, and extraction efficiencies higher than 87,% were achieved. The quantitative extraction is obtained by using different fluorinated ,-diketones with and without the addition of tri(n -butyl)phosphate. The complexation phenomenon occurring in the room-temperature ionic-liquid (RTIL) phase was evidenced by using luminescence spectroscopy. [source]

First Application of Calixarenes as Extractants in Room-Temperature Ionic Liquids.

CHEMINFORM, Issue 33 2004
Kojiro Shimojo
Abstract For Abstract see ChemInform Abstract in Full Text. [source]

Solvation of Uranyl(II), Europium(III) and Europium(II) Cations in "Basic" Room-Temperature Ionic Liquids: A Theoretical Study

CHEMISTRY - A EUROPEAN JOURNAL, Issue 16 2004
Alain Chaumont
Abstract We report a molecular dynamics study of the solvation of UO22+, Eu3+ and Eu2+ ions in two "basic" (Lewis acidity) room-temperature ionic liquids (IL) composed of the 1-ethyl-3-methylimidazolium cation (EMI+) and a mixture of AlCl4, and Cl, anions, in which the Cl,/AlCl4, ratio is about 1 and 3, respectively. The study reveals the importance of the [UO2Cl4]2, species, which spontaneously form during most simulations, and that the first solvation shell of europium is filled with Cl, and AlCl4, ions embedded in a cationic EMI+ shell. The stability of the [UO2Cl4]2, and [EuIIICl6]3, complexes is supported by quantum mechanical calculations, according to which the uranyl and europium cations intrinsically prefer Cl, to the AlCl4, ion. In the gas phase, however, [EuIIICl6]3, and [EuIICl6]4, complexes are predicted to be metastable and to lose two to three Cl, ions. This contrasts with the results of simulations of complexes in ILs, in which the "solvation" of the europium complexes increases with the number of coordinated chlorides, leading to an equilibrium between different chloro species. The behavior of the hydrated [Eu(OH2)8]3+ complex is considered in the basic liquids; the complex exchanges H2O molecules with Cl, ions to form mixed [EuCl3(OH2)4] and [EuCl4(OH2)3], complexes. The results of the simulations allow us to better understand the microscopic nature and solvation of lanthanide and actinide complexes in "basic" ionic liquids. [source]

Ethenolysis of Methyl Oleate in Room-Temperature Ionic Liquids

CHEMSUSCHEM CHEMISTRY AND SUSTAINABILITY, ENERGY & MATERIALS, Issue 1-2 2008
Cyril Thurier
Abstract Unsaturated vegetable oils are an attractive renewable feedstock, and the selective cleavage of unsaturated fatty esters is an important transformation in this respect. The efficient and selective cross-metathesis of methyl oleate with ethylene was achieved under mild conditions with ruthenium-alkylidene catalysts in toluene and room-temperature ionic liquids (RTILs) to give two important chemical intermediates, 1-decene and methyl 9-decenoate, without double-bond migration. As recovery of the catalyst is an important target with respect to industrial applications, catalyst recycling studies were also carried out in RTILs with the first-generation Hoveyda catalyst. [source]

Acute and chronic toxicity of imidazolium-based ionic liquids on Daphnia magna

ENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 1 2005
Randall J. Bernot
Abstract Room-temperature ionic liquids (ILs) are considered to be green chemicals that may replace volatile organic solvents currently used by industry. However, IL effects on aquatic organisms and ecosystems are currently unknown. We studied the acute effects of imidazolium-based ILs on survival of the crustacean Daphnia magna and their chronic effects on number of first-brood neonates, total number of neonates, and average brood size. Lethal concentrations of imidazolium ILs with various anions (X,) ranged from a median lethal concentration (LC50) of 8.03 to 19.91 mg L,1, whereas salts with a sodium cation (Na+ X,) were more than an order of magnitude higher (NaPF6 LC50, 9,344.81 mg L,1; NaBF4 LC50, 4765.75 mg L,1). Thus, toxicity appeared to be related to the imidazolium cation and not to the various anions (e.g., CI,, Br,, PF,6, and BF,4). The toxicity of imidazolium-based ILs is comparable to that of chemicals currently used in manufacturing and disinfection processes (e.g., ammonia and phenol), indicating that these green chemicals may be more harmful to aquatic organisms than current volatile organic solvents. We conducted 21-d chronic bioassays of individual D. magna exposed to nonlethal IL concentrations at constant food-resource levels. Daphnia magna produced significantly fewer total neonates, first-brood neonates, and average neonates when exposed to lower concentrations (0.3 mg L,1) of imidazolium-based ILs than in the presence of Na-based salts at higher concentrations (400 mg L,1). Such reductions in the reproductive output of Daphnia populations could cascade through natural freshwater ecosystems. The present study provides baseline information needed to assess the potential hazard that some ILs may pose should they be released into freshwater ecosystems. [source]

1D and 3D Ionic Liquid,Aluminum Hydroxide Hybrids Prepared via an Ionothermal Process,

ADVANCED FUNCTIONAL MATERIALS, Issue 14 2007
S. Park
Abstract Room-temperature ionic liquids (RTILs) are used as hierarchically multifunctional components by employing them not only as templates and co-solvents for fabricating nanostructured materials but also proton conductors for electrochemical devices. RTIL/aluminum hydroxide (RTIL,Al) hybrids containing various nanometer-sized shapes, including 1D nanorods with hexagonal tips, straight and curved nanofibers, nanofibers embedded in a porous network, and 3D octahedral-, polyhedral-, and angular spherical shapes are synthesized via a one-pot ionothermal process. The structures or shapes of the RTIL,Al hybrids are related to the anionic moieties, alkyl chain length of the RTILs, and the humidity during fabrication. In particular, the introduction of water molecules into the interface led to 3D isotropic growth of the hybrids by influencing intermolecular interactions between the RTILs and the building blocks. The shapes of the nanohybrids fabricated from RTILs containing short alkyl chains were dependent on the types of anions and on the level of humidity. These results indicate that the cooperative interactions between RTILs and aluminum hydroxides induces emerging shape-controlled hybrids. The shape-controlled nanohybrids show enhanced electrochemical properties compared to those of a conventional hybrid prepared by mixing RTILs and aluminum hydroxides, exhibiting tenfold or higher proton conductivity under anhydrous condition and thermal stability as a result of the continuous proton conduction channel and the one-pot-assembled nanoconfinement. This method is expected to be a useful technique for controlling the diverse shapes of nanometer-sized crystalline inorganic materials for a variety of applications, such as fuel cells, solar cells, rechargeable batteries, and biosensors. [source]

Probing the Local Structure of Pure Ionic Liquid Salts with Solid- and Liquid-State NMR,

CHEMPHYSCHEM, Issue 1 2010
Peter G. Gordon
Abstract Room-temperature ionic liquids (RTILs) are gaining increasing interest and are considered part of the green chemistry paradigm due to their negligible vapour pressure and ease of recycling. Evidence of liquid-state order, observed by IR and Raman spectroscopy, diffraction studies, and simulated by ab initio methods, has been reported in the literature. Here, quadrupolar nuclei are used as NMR probes to extract information about the solid and possible residual order in the liquid state of RTILs. To this end, the anisotropic nature and field dependence of quadrupolar and chemical shift interactions are exploited. Relaxation time measurements and a search for residual second-order quadrupolar coupling were employed to investigate the molecular motions present in the liquid state and infer what kind of order is present. The results obtained indicate that on a timescale of ,10,8 sec or longer, RTILs behave as isotropic liquids without residual order. [source]

Raman spectra indicative of unusual water structure in crystals formed from a room-temperature ionic liquid

JOURNAL OF RAMAN SPECTROSCOPY, Issue 11 2006
Hiroko Miki
Abstract Formation of crystals with unusual water structure has been found to take place in an ionic liquid 1-butyl-3-methylimidazolium tetrachloroferrate (bmim[FeCl4]). The Raman spectrum of a crystal formed in bmim[FeCl4] showed two prominent Raman bands ascribed to H2O. Another crystal formed in bmim[FeCl4] exposed to D2O atmosphere showed Raman bands of H2O, HOD and D2O. These findings indicate that an unusually high concentration of water is contained in the crystals. The observed Raman bands of the HOH, HOD and DOD bending modes are unusually narrow, implying an unknown unique structure of water. Copyright © 2006 John Wiley & Sons, Ltd. [source]

Comparison of ethylammonium formate to methanol as a mobile-phase modifier for reversed-phase liquid chromatography

JOURNAL OF SEPARATION SCIENCE, JSS, Issue 5 2006
Martin M. Waichigo
Abstract Ethylammonium formate (EAF), (C2H5NH3+HCO2,), is a room-temperature ionic liquid that has a polarity similar to that of methanol (MeOH) or acetonitrile. The separation at 1 mL/min of a test mixture of vitamins or phenols on a polystyrene-divinylbenzene column using either an EAF- or MeOH-water mobile phase is similar in terms of both resolution and analysis time. Because the viscosity of EAF is higher than that of MeOH, the plate count for phenol at room temperature is lower by about a factor of 1.1,1.4 depending on the flow rate. However, van Deemter plots show that this loss in plate count at 1 mL/min can be recovered and improved from 1500 to 2400 plates by working at a slightly elevated temperature of 55°C. A slower flow rate such as 0.8 mL/min can also substantially improve the plate count as compared to 1,1.5 mL/min. Log P (octanol partition coefficient) versus log k, data for a variety of neutral test solutes are again similar whether EAF or MeOH is used as the organic modifier. Resolution of certain peak pairs such as 2,4-dinitrophenol/2,4,6-trinitrophenol and p -aminobenzoate/benzoate is enhanced using EAF as compared to MeOH. One advantage of EAF is that control of retention of solutes such as water-soluble vitamins under totally aqueous mobile phase conditions is environmentally preferable for quality control applications. In addition, EAF seems to be a milder mobile-phase modifier than MeOH for certain proteins such as lysozyme. [source]

Effects of Ionic Liquid [Me3NC2H4OH]+[ZnCl3], on , -Radiation Polymerization of Methyl Methacrylate in Ethanol and N,N -Dimethylformamide

MACROMOLECULAR RAPID COMMUNICATIONS, Issue 1 2005
Guozhong Wu
Abstract Summary: Radiation-induced polymerization of methyl methacrylate (MMA) in ethanol (EtOH) and N,N -dimethylformamide (DMF) in the presence of ionic liquid [Me3NC2H4OH]+[ZnCl3], is reported. A substantial increase in monomer conversion and molecular weight is observed at room-temperature ionic liquid (RTIL) >60 vol.-%, and the resulting PMMA has a broad multimodal MWD. A clear difference in the MWD pattern is noted between EtOH/RTIL and DMF/RTIL systems, probably due to the complicated interactions between the solvent and ionic liquid. Gel permeation chromatography traces of poly(methyl methacrylate) obtained by radiation polymerization in EtOH/RTIL and DMF/RTIL mixed solvent. Organic/RTIL (v/v): 1) 100:0; 2) 80:20; 3) 60:40; 4); 40:60; 5) 0:100. [source]

Synthesis and Characterization of Pyrazolyl-Functionalized Imidazolium-Based Ionic Liquids and Hemilabile (Carbene)palladium(II) Complex Catalyzed Heck Reaction

EUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 4 2007
Ruihu Wang
Abstract Neat reactions of 1-(pyrazolylmethyl)imidazole with an excess of alkyl or polyfluoroalkyl halides at 100 °C followed by subsequent metathetical reactions with LiN(SO2CF3)2 or KPF6 at 25 °C gave rise to a series of monoquaternary salts 3a,3k. These salts can be also prepared through treatment of 1-alkylimidazole with 1-(chloromethyl)pyrazole hydrochloride in the presence of base, followed by anion exchange with LiN(SO2CF3)2 or KPF6. Their phase-transition temperature, thermal stability, density and solubility in common solvents have been investigated. Most of the bis(trifluoromethanesulfon)amide salts are room-temperature ionic liquids. The effect of anions and of alkyl substituents bonded to the imidazolium cation on the physicochemical properties was examined. Using 3-butyl-1-(pyrazolylmethyl)imidazolium chloride (2d), the precursor of 3-butyl-1-(pyrazolylmethyl)imidazolium bis(trifluoromethanesulfon)amide (3d), as a reactant, a hemilabile (N-heterocyclic carbene)palladium(II) complex 4 was synthesized through a (carbene)silver(I) transfer reagent. It was characterized by single-crystal X-ray diffraction analysis. The catalytic activity and recyclability of 4 in 3d were preliminarily evaluated by consecutive Heck reactions using different substrates. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007) [source]

New aluminum-based ionic liquids: Synthesis, characterization, and theoretical study

HETEROATOM CHEMISTRY, Issue 7 2009
Hossein Tavakol
Synthesis, characterization, spectral and molecular parameters of some new room-temperature ionic liquids (tetraalkylammonium bromotrichloro aluminum [R4N]+[AlCl3Br],) have been studied in the present study. All synthesized ionic liquids were characterized by IR, 1H, 13C, and 81Br-NMR. In addition, synthesized structures were optimized at the B3LYP/LANL2DZ level of theory and then the structures, molecular specifications, and infrared spectra of these were extracted using Gaussian 03 program. Theoretical data show good agreement with the experimental results. © 2010 Wiley Periodicals, Inc. Heteroatom Chem 20:398,404, 2009; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/hc.20564 [source]

Efficient Intramolecular Hydroalkoxylation of Unactivated Alkenols Mediated by Recyclable Lanthanide Triflate Ionic Liquids: Scope and Mechanism

CHEMISTRY - A EUROPEAN JOURNAL, Issue 11 2010
Alma Dzudza Dr.
Abstract Lanthanide triflate complexes of the type [Ln(OTf)3] (Ln=La, Sm, Nd, Yb, Lu) serve as effective, recyclable catalysts for the rapid intramolecular hydroalkoxylation (HO)/cyclization of primary/secondary and aliphatic/aromatic hydroxyalkenes in imidazolium-based room-temperature ionic liquids (RTILs) to yield the corresponding furan, pyran, spirobicyclic furan, spirobicyclic furan/pyran, benzofuran, and isochroman derivatives. Products are straightforwardly isolated from the catalytic solution, conversions exhibit Markovnikov regioselectivity, and turnover frequencies are as high as 47,h,1 at 120,°C. The ring-size rate dependence of the primary alkenol cyclizations is 5>6, consistent with a sterically controlled transition state. The hydroalkoxylation/cyclization rates of terminal alkenols are slightly more rapid than those of internal alkenols, which suggests modest steric demands in the cyclic transition state. Cyclization rates of aryl-functionalized hydroxyalkenes are more rapid than those of the linear alkenols, whereas five- and five/six-membered spirobicyclic skeletons are also regioselectively closed. In cyclization of primary, sterically encumbered alkenols, turnover-frequency dependence on metal-ionic radius decreases by approximately 80-fold on going from La3+ (1.160,Å) to Lu3+ (0.977,Å), presumably reflecting steric impediments along the reaction coordinate. The overall rate law for alkenol hydroalkoxylation/cyclization is v,k[catalyst]1[alkenol]1. An observed ROH/ROD kinetic isotope effect of 2.48 (9) is suggestive of a catalytic pathway that involves kinetically significant intramolecular proton transfer. The present activation parameters,enthalpy (,H,)=18.2 (9),kcal,mol,1, entropy (,S,)=,17.0 (1.4),eu, and energy (Ea)=18.2 (8),kcal,mol,1,suggest a highly organized transition state. Proton scavenging and coordinative probing results suggest that the lanthanide triflates are not simply precursors of free triflic acid. Based on the kinetic and mechanistic evidence, the proposed catalytic pathway invokes hydroxyl and olefin activation by the electron-deficient Ln3+ center, and intramolecular H+ transfer, followed by alkoxide nucleophilic attack with ring closure. [source]