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Room-temperature ionic liquid battery electrolytes  

Microsoft Academic Search

Room-temperature molten salts possess a number of unique properties that make them ideal battery electrolytes. In particular, they are nonflammable, nonvolatile and chemically inert, and they display wide electrochemical windows, high inherent conductivities and wide thermal operating ranges. Although these ionic liquids have excellent characteristics, the chemical and electrochemical properties of desirable battery electrode materials are not well understood in

R. T. Carlin; J. Fuller



Electrochemistry of room temperature protic ionic liquids.  


Eighteen protic ionic liquids containing different combinations of cations and anions, hydrophobicity, viscosity, and conductivity have been synthesized and their physicochemical properties determined. In one series, the diethanolammonium cations were combined with acetate, formate, hydrogen sulfate, chloride, sulfamate, and mesylate anions. In the second series, acetate and formate anions were combined with amine bases, triethylamine, diethylamine, triethanolamine, di-n-propylamine, and di-n-butylamine. The electrochemical characteristics of the eight protic ionic liquids that are liquid at room temperature (RTPILs) have been determined using cyclic, microelectrode, and rotating disk electrode voltammetries. Potential windows of the RTPILs have been compared at glassy carbon, platinum, gold, and boron-doped diamond electrodes and generally found to be the largest in the case of glassy carbon. The voltammetry of IUPAC recommended potential scale reference systems, ferrocene/ferrocenium and cobaltocenium/cobaltocene, have been evaluated and found to be ideal in the case of the less viscous RTPILs but involve adsorption in the highly viscous ones. Other properties such as diffusion coefficients, ionic conductivity, and double layer capacitance also have been measured. The influence of water on the potential windows, viscosity, and diffusion has been studied systematically by deliberate addition of water to the dried ionic liquids. The survey highlights the problems with voltammetric studies in highly viscous room temperature protic ionic liquids and also suggests the way forward with respect to their possible industrial use. PMID:18489145

Zhao, Chuan; Burrell, Geoff; Torriero, Angel A J; Separovic, Frances; Dunlop, Noel F; MacFarlane, Douglas R; Bond, Alan M



Electrochemical Generation of Superoxide in Room-Temperature Ionic Liquids  

E-print Network

on superoxide ion (O2 · ), particularly the direct electrochemical reduction of dissolved oxygen gas in aproticElectrochemical Generation of Superoxide in Room-Temperature Ionic Liquids Inas M. Al demonstrated that superoxide ion can be generated electrochemically in room-temperature ionic-liquid solvents

Weidner, John W.


Room-Temperature Ionic Liquids for Electrochemical Capacitors  

NASA Technical Reports Server (NTRS)

A document discusses room-temperature ionic liquids (RTILs) used as electrolytes in carbon-nanotube-based, electrochemical, double-layer capacitors. Unlike the previous electrolyte (EtNB4 in acetonitrile), the RTIL used here does not produce cyanide upon thermal decomposition and does not have a moisture sensitivity.

Fireman, Heather; Yowell, Leonard; Moloney, Padraig G.; Arepalli, Sivaram; Nikolaev, P.; Huffman, C.; Ready, Jud; Higgins, C.D.; Turano, S. P.; Kohl, P.A.; Kim, K.



Phosphonium chloromercurate room temperature ionic liquids of variable composition.  


The system trihexyl(tetradecyl)phosphonium ([P66614]Cl)/mercury chloride (HgCl2) has been investigated by varying the stoichiometric ratios from 4:1 to 1:2 (25, 50, 75, 100, 150, and 200 mol % HgCl2). All investigated compositions turn out to give rise to ionic liquids (ILs) at room temperature. The prepared ionic liquids offer the possibility to study the structurally and compositionally versatile chloromercurates in a liquid state at low temperatures in the absence of solvents. [P66614]2[HgCl4] is a simple IL with one discrete type of anion, while [P66614]{HgCl3} (with {} indicating a polynuclear arrangement) is an ionic liquid with a variety of polyanionic species, with [Hg2Cl6](2-) apparently being the predominant building block. [P66614]2[Hg3Cl8] and [P66614][Hg2Cl5] appear to be ILs at ambient conditions but lose HgCl2 when heated in a vacuum. For the liquids with the compositions 4:1 and 4:3, more than two discrete ions can be evidenced, namely, [P66614](+), [HgCl4](2-), and Cl(-) and [P66614](+), [HgCl4](2-), and the polynuclear {HgCl3}(-), respectively. The different stoichiometric compositions were characterized by (199)Hg NMR, Raman- and UV-vis spectroscopy, and cyclic voltammetry, among other techniques, and their densities and viscosities were determined. The [P66614]Cl/HgCl2 system shows similarities to the well-known chloroaluminate ILs (e.g., decrease in viscosity with increasing metal content after addition of more than 0.5 mol of HgCl2/mol [P66614]Cl, increasing density with increasing metal content, and the likely formation of polynuclear/polymeric/polyanionic species) but offer the advantage that they are air and water stable. PMID:24274831

Metlen, Andreas; Mallick, Bert; Murphy, Richard W; Mudring, Anja-Verena; Rogers, Robin D



Pronounced structure in confined aprotic room-temperature ionic liquids.  


Room-temperature ionic liquids (ILs) are attracting considerable research interest as replacements for traditional molecular solvents in a diverse range of chemical applications, mostly due to their green characteristics and remarkable physical properties. Previously, we reported the liquid structure of 1-ethyl-3-methylimidazolium acetate confined between mica and an atomic force microscope (AFM) tip, and found that approximately three solvation layers form. In this manuscript, we present new data, derived from similar experiments, for three different aprotic ILs [1-butyl-3-methylimidazolium hexafluorphosphate (BMIm PF6), 1-ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl) imide (EMIm TSFA), and 1-butyl-1-methylpyrrolidinium bis(trifluoromethanesulfonyl) imide (BMP TSFA)] and between five and six solvation layers are identified depending on the IL species. These new results allow us to make suggestions for molecularly designing IL architectures likely to be suitable for a particular application, depending on whether near surface order is desirable or not. Where mobility of component ions and transfer of species to and from the interface is required (DSSCs, hetereogeneous catalysis, etc.), multiple sterically hindered allylic functional groups could be incorporated to minimize substrate-IL interactions and maximize compressibility of the solvation layers. Conversely, in situations where IL adsorption to the interface is desirable (e.g., lubrication or electrode surface restructuring), symmetric ions with localized charge centers are preferable. PMID:19438273

Hayes, Robert; El Abedin, Sherif Zein; Atkin, Rob



Synthesis of tin nanocrystals in room temperature ionic liquids.  


The aim of this work was to investigate the synthesis of tin nanoparticles (NPs) or tin/carbon composites, in room temperature ionic liquids (RTILs), that could be used as structured anode materials for Li-ion batteries. An innovative route for the synthesis of Sn nanoparticles in such media is successfully developed. Compositions, structures, sizes and morphologies of NPs were characterized by high-energy X-ray diffraction (HEXRD), X-ray photoelectron spectroscopy (XPS) and high-resolution transmission electron microscopy (HRTEM). Our findings indicated that (i) metallic tetragonal ?-Sn was obtained and (ii) the particle size could be tailored by tuning the nature of the RTILs, leading to nano-sized spherical particles with a diameter ranging from 3 to 10 nm depending on synthesis conditions. In order to investigate carbon composite materials for Li-ion batteries, Sn nanoparticles were successfully deposited on the surface of multi-wall carbon nanotubes (MWCNT). Moreover, electrochemical properties have been studied in relation to a structural study of the nanocomposites. The poor electrochemical performances as a negative electrode in Li-ion batteries is due to a significant amount of RTIL trapped within the pores of the nanotubes as revealed by XPS investigations. This dramatically affected the gravimetric capacity of the composites and limited the diffusion of lithium. The findings of this work however offer valuable insights into the exciting possibilities for synthesis of novel nano-sized particles and/or alloys (e.g. Sn-Cu, Sn-Co, Sn-Ni, etc.) and the importance of carbon morphology in metal pulverization during the alloying/dealloying process as well as prevention of ionic liquid trapping. PMID:25352309

Le Vot, Steven; Dambournet, Damien; Groult, Henri; Ngo, Anh-Tu; Petit, Christophe; Rizzi, Cécile; Salzemann, Caroline; Sirieix-Plenet, Juliette; Borkiewicz, Olaf J; Raymundo-Piñero, Encarnación; Gaillon, Laurent



Proactive aquatic ecotoxicological assessment of room-temperature ionic liquids  

USGS Publications Warehouse

Aquatic environments are being contaminated with a myriad of anthropogenic chemicals, a problem likely to continue due to both unintentional and intentional releases. To protect valuable natural resources, novel chemicals should be shown to be environmentally safe prior to use and potential release into the environment. Such proactive assessment is currently being applied to room-temperature ionic liquids (ILs). Because most ILs are water-soluble, their effects are likely to manifest in aquatic ecosystems. Information on the impacts of ILs on numerous aquatic organisms, focused primarily on acute LC50 and EC50 endpoints, is now available, and trends in toxicity are emerging. Cation structure tends to influence IL toxicity more so than anion structure, and within a cation class, the length of alkyl chain substituents is positively correlated with toxicity. While the effects of ILs on several aquatic organisms have been studied, the challenge for aquatic toxicology is now to predict the effects of ILs in complex natural environments that often include diverse mixtures of organisms, abiotic conditions, and additional stressors. To make robust predictions about ILs will require coupling of ecologically realistic laboratory and field experiments with standard toxicity bioassays and models. Such assessments would likely discourage the development of especially toxic ILs while shifting focus to those that are more environmentally benign. Understanding the broader ecological effects of emerging chemicals, incorporating that information into predictive models, and conveying the conclusions to those who develop, regulate, and use those chemicals, should help avoid future environmental degradation. ?? 2011 Bentham Science Publishers Ltd.

Kulacki, K.J.; Chaloner, D.T.; Larson, J.H.; Costello, D.M.; Evans-White, M. A.; Docherty, K.M.; Bernot, R.J.; Brueseke, M.A.; Kulpa, C.F.; Lamberti, G.A.



Dynamics of Isolated Water Molecules in a Sea of Ions in a Room Temperature Ionic Liquid  

E-print Network

Dynamics of Isolated Water Molecules in a Sea of Ions in a Room Temperature Ionic Liquid Daryl B2O molecules in the room temperature ionic liquid (RTIL) 1-butyl-3-methylimidazolium resolved in the IR absorption spectrum in spite of the fact that the D2O is surrounded by a sea of ions

Fayer, Michael D.


Applications of room temperature ionic liquids in interfacial polymerization  

NASA Astrophysics Data System (ADS)

Room temperature ionic liquids (ILs), with their unique physical and chemical properties, have been of great interest in various areas of chemical science and engineering during the last decade. In this dissertation, polyurea and polyamide films with surface nanostructures were synthesized by interfacial polymerization (IP) with ILs without stirring. Both polymers were prepared at the interface between n-hexane and a series of 1-alkyl-3-methylimidazolium ILs. Nanoporous or nanofibrous polymer morphologies with various sizes ranging from 50 to 500 nm and geometries, depending on the ILs used, were observed by scanning electron microscopy (SEM). A correlation length of ˜20nm and a suppression of three-dimensional (3-D) crystalline structure of the polyurea were found by small angle X-ray scattering (SAXS) and X-ray diffraction (XRD), respectively. FTIR spectra showed no significant changes in the chemical composition of the polymer by the employment of ILs. The peculiar nanostructure of the polymer could be ascribed to the intermolecular interactions between the ILs and the polymer, which affected the development of the polymer morphology. The polyamides prepared with ILs showed larger intrinsic viscosities, and consequently higher molecular weights, compared to the one prepared without ILs; this could be due to the prevention of the side reaction between sebacoyl chloride and water. The enhancement of the molecular weight renders a better thermal stability to the polyamide film, as revealed by thermogravimetric analysis (TGA) which showed a higher decomposition temperature. Coating of fine particulates with polyurea by IP has been developed. With increasing stirring speed in the coating process, a decreased mean particle size and a narrower particle size distribution, as well as a lower coating weight percentage were found by particle size analysis and TGA, respectively. A Porous coating layer was formed in the IP coating in the presence of ILs. The reaction kinetics of Nylon 610 film formation with ILs were studied by measuring the product mass at different reaction times. The polymer film ceased to grow in the late stage of the reaction due to the diffusion barrier formed by the film. The characteristic time marking the cessation of the film growth was found to be dependent on the initial reactant concentrations. The evolution of the polymer molecular weight with reaction time was monitored by intrinsic viscosity measurements. It is found that the molecular weight leveled off faster than the film growth under the same reactant concentrations. Based on our experimental studies, a simplified diffusion-controlled mathematical model of IP with ILs was developed, in which the effective diffusivity in the polymer film decayed with the square of time. The model was used to fit the measured growth rate of the polymer film and the fitting results showed a conspicuously good agreement between the model and the experimental data. Physical properties of ILs relevant to the biphasic systems were also studied in this work. The interfacial tensions between organic solvents and ILs were found to decrease with ascending alkyl chain length attached to the imidazolium cations. In general, the interfacial tensions between ILs and aromatic solvents are lower than the ones with aliphatic solvents; this is attributed to the pi-pi interactions between ILs and the aromatic solvent. Self-aggregation of IL molecules in aqueous solutions and self-aggregation of ethanol in ILs are suggested based on the interfacial tension measurements. These properties are important in multi-phase chemical processes. Our study has demonstrated the potential application of ionic liquids in the interfacial polymerization of polymers with nanoscale structures.

Zhu, Lining


Zwitterionic polymersomes in an ionic liquid: room temperature TEM characterization.  


Conventional transmission electron microscopy (TEM) was utilized to characterize vesicles formed by the spontaneous self-assembly of a novel zwitterionic block copolymer in the ionic liquid (2-hydroxyethyl)dimethylammonium methanesulfonate as well as in 0.1 M phosphate buffered saline (PBS). This block copolymer was synthesized via ring-opening metathesis polymerization (ROMP) of a norbornene-based sulfobetaine, followed by its end-functionalization with polystyrene to generate the necessary amphiphilic structure. The ionic liquid enabled the visualization of the vesicles in their swollen state by TEM, demonstrating a new method for improved characterization of polymer vesicles. PMID:21902263

Maddikeri, Raghavendra R; Colak, Semra; Gido, Samuel P; Tew, Gregory N



Diels-Alder reactions in room-temperature ionic liquids  

Microsoft Academic Search

The Diels-Alder cycloaddition reaction between methyl acrylate and cyclopentadiene has been investigated in a number of air and moisture stable ionic liquids. The endo\\/exo ratio of the reaction has been used as an initial probe of the nature of the solvents.

T. Fischer; A. Sethi; T. Welton; J. Woolf



A facile and efficient nucleophilic displacement reaction at room temperature in ionic liquids  

Microsoft Academic Search

We have investigated the use of room temperature ionic liquids as catalytic and environmentally benign solvents for the facile homogenous synthesis of benzyl salicylate by the nucleophilic displacement reaction between sodium salicylate and benzyl chloride. The reaction was found to proceed under relatively mild conditions with excellent conversion (up to 96%) without the use of PTCs. The ionic liquids were

Zaher M. A Judeh; Hao-Yu Shen; Bun Ching Chi; Li-Chun Feng; Selvaratnam Selvasothi



Room-temperature ionic liquids: new solvents for f-element separations and associated solution chemistry  

Microsoft Academic Search

Ionic liquids (ILs) are composed of organic cations and either organic or inorganic anions that remain liquid over a wide temperature range, including room temperature. IL characteristics can be dramatically adjusted (e.g., hydrophobic vs. hydrophilic) by changing the anion type, or subtly altered by changing the length or number of alkyl groups appended to the cation. Changing alkyl chain lengths

Ann E Visser; Robin D Rogers



Isomer effect of propanol on liquid-liquid equilibrium in hydrophobic room-temperature ionic liquids  

NASA Astrophysics Data System (ADS)

The cloud-point temperature determined the liquid-liquid phase equilibrium (LLE) of binary systems comprising hydrophobic room-temperature ionic liquids (RTILs) and propanol. The RTILs were 1-alkyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide, [Cxmim][TFSI] (2 ? x ? 10). Upper critical solution temperatures in LLE are inversely proportional to the Cxmim+ cation alkyl chain length, x. The propanol isomer effect indicates the critical alkyl chain length (xcritical = 6-7). UNIQUAC model determined the interaction parameters (with crossing points at x = 6). In pure RTILs, conformation stability of TFSI- by Raman spectroscopy changed between x = 6 and 7, corresponding to the simulation-determined 90°-torsion angle at x = 6.

Ozawa, Shinichiro; Kishimura, Hiroaki; Kitahira, Shota; Tamatani, Kentaro; Hirayama, Kentaro; Abe, Hiroshi; Yoshimura, Yukihiro



Formation and reactions of alkylzinc reagents in room-temperature ionic liquids.  


[reaction: see text] The presence of a suitable amount of bromide or chloride ions was found to be critical in forming the alkylzinc reagents from alkyl iodides and zinc metal in the room-temperature ionic liquid, N-butylpyridinium tetrafluoroborate. Beta-hydride transfer in the reactions of butylzinc reagents with aldehydes can also be reduced by a bromide ion. PMID:16323854

Law, Man Chun; Wong, Kwok-Yin; Chan, Tak Hang




Microsoft Academic Search

One area of on-going research in our group at Los Alamos National Laboratory is directed toward characterization of the basic coordination chemistry and electrochemical behavior of f-element ions dissolved in room temperature ionic liquids (RTILs). The ultimate goal of this work is to introduce advanced, environmentally sustainable, nuclear processing and purification strategies into both the DOE complex and the civilian




Fabrication of a Miniaturized Room Temperature Ionic Liquid Gas Sensor for Human Health and  

E-print Network

time, low power consumption, and small footprint is needed. A promising approach is to utilize an electrochemical sensing methodology[4] with room temperature ionic liquids (RTILs) as the sensing media[5]. When sensing gases, electrochemical methods provide good selectivity with low power consumption and wide

Mason, Andrew


Friedel–Crafts acylation of indoles in acidic imidazolium chloroaluminate ionic liquid at room temperature  

Microsoft Academic Search

A practical and convenient protocol has been developed for the acidic 1-ethyl-3-methylimidazolium chloroaluminate ionic liquid (generated from 1-ethyl-3-methylimidazolium chloride (EmimCl) and aluminium chloride (X(AlCl3), mole fraction X=0.67–0.75) promoted Friedel–Crafts acylation of indoles at room temperature. The simple experimental procedure provides 3-substituted indoles in good to high yields with less electron rich indole ring systems.

Kap-Sun Yeung; Michelle E Farkas; Zhilei Qiu; Zhong Yang



Anion pairs in room temperature ionic liquids predicted by molecular dynamics simulation, verified by spectroscopic characterization  

SciTech Connect

Molecular-level spectroscopic analyses of an aprotic and a protic room-temperature ionic liquid, BMIM OTf and BMIM HSO4, respectively, have been carried out with the aim of verifying molecular dynamics simulations that predict anion pair formation in these fluid structures. Fourier-transform infrared spectroscopy, Raman spectroscopy and nuclear magnetic resonance spectroscopy of various nuclei support the theoretically-determined average molecular arrangements.

Schwenzer, Birgit; Kerisit, Sebastien N.; Vijayakumar, M.




SciTech Connect

One area of on-going research in our group at Los Alamos National Laboratory is directed toward characterization of the basic coordination chemistry and electrochemical behavior of f-element ions dissolved in room temperature ionic liquids (RTILs). The ultimate goal of this work is to introduce advanced, environmentally sustainable, nuclear processing and purification strategies into both the DOE complex and the civilian nuclear industry. Efforts to develop ambient temperature electrorefining and/or electrowinning technologies are focused on the design of ionic liquids characterized by extended cathodic stability. In this chapter a summary of the synthesis, physical properties and electrochemical behavior of the ionic liquids used in this work is presented. The feasibility of efficient electrochemical production of high electropositive metals is demonstrated through reversible plating and stripping of sodium and potassium metals.




Reversible swelling of the cell wall of poplar biomass by ionic liquid at room temperature.  


Time-resolved autofluorescence, Raman microspectroscopy, and scanning microprobe X-ray diffraction were combined in order to characterize lignocellulosic biomass from poplar trees and how it changes during treatment with the ionic liquid 1-n-ethyl-3-methylimidazolium acetate (EMIMAC) at room temperature. The EMIMAC penetrates the cell wall from the lumen, swelling the cell wall by about a factor of two towards the empty lumen. However, the middle lamella remains unchanged, preventing the cell wall from swelling outwards. During this swelling, most of the cellulose microfibrils are solubilized but chain migration is restricted and a small percentage of microfibrils persist. When the EMIMAC is expelled, the cellulose recrystallizes as microfibrils of cellulose I. There is little change in the relative chemical composition of the cell wall after treatment. The action of EMIMAC on the poplar cell wall at room temperature would therefore appear to be a reversible swelling and a reversible decrystallization of the cell wall. PMID:21247757

Lucas, Marcel; Wagner, Greg L; Nishiyama, Yoshiharu; Hanson, Leif; Samayam, Indira P; Schall, Constance A; Langan, Paul; Rector, Kirk D



Scanning Electron Microscope Observation of Nano Carbon Materials with Imidazolium-Type Room Temperature Ionic Liquids  

NASA Astrophysics Data System (ADS)

A novel pre-treatment method for scanning electron microscopy (SEM) observation using room temperature ionic liquids (ILs) was used for several carbon nano materials. After the ILs pre-treatment, the quality of the SEM images obtained was almost the same as that obtained with conventional platinum/palladium (Pt/Pd) spattering pre-treatment. The highest resolution in this study was under 30 nm. This result means that the pre-treatment with IL can form ultrathin layer on the sample surface at several molecules level. Therefore, the ILs pre-treatment is a simple and easy tool for SEM observation of nano materials on insulating substrates.

Abe, Shigeaki; Hyono, Atsushi; Nakayama, Katsutoshi; Takada, Tomoya; Yonezawa, Tetsu



Influence of solvent structural variations on the mechanism of facilitated ion transfer into room-temperature ionic liquids  

SciTech Connect

The predominant mode of strontium ion transfer from acidic nitrate media into a series of 1-alkyl-3-methylimidazolium-based room-temperature ionic liquids containing dicyclohexano-18-crown-6 (DCH18C6) shifts from cation exchange to strontium nitrato-crown ether complex partitioning as the hydrophobicity of the ionic liquid cation is increased.

Dietz, M. L.; Dzielawa, J. A.; Laszak, I.; Jensen, M. P.; Young, B. A.; Chemistry



Mechanisms of metal ion transfer into room-temperature ionic liquids : the role of anion exchange.  

SciTech Connect

The structure and stoichiometry of the lanthanide(III) (Ln) complexes with the ligand 2-thenoyltrifluoroacetone (Htta) formed in a biphasic aqueous room-temperature ionic liquid system have been studied by complementary physicochemical methods. Equilibrium thermodynamics, optical absorption and luminescence spectroscopies, high-energy X-ray scattering, EXAFS, and molecular dynamics simulations all support the formation of anionic Nd(tta){sub 4}{sup -} or Eu(tta){sub 4}{sup -} complexes with no water coordinated to the metal center in 1-butyl-3-methylimidazolium bis[(trifluoromethyl)sulfonyl]imide (C{sub 4}mim{sup +}Tf{sub 2}N{sup -}), rather than the hydrated, neutral complexes, M(tta){sub 3}(H{sub 2}O){sub n} (n = 2 or 3), that form in nonpolar molecular solvents, such as xylene or chloroform. The presence of anionic lanthanide complexes in C{sub 4}mim{sup +}Tf{sub 2}N{sup -} is made possible by the exchange of the ionic liquid anions into the aqueous phase for the lanthanide complex. The resulting complexes in the ionic liquid phase should be thought of as weak C{sub 4}mim{sup +}Ln(tta){sub 4}{sup -} ion pairs which exert little influence on the structure of the ionic liquid phase.

Jensen, M. P.; Neuefeind, J.; Beitz, J. V.; Skanthakumar, S.; Soderholm, L.; Chemistry



Fission-Product Separation Based on Room-Temperature Ionic-Liquids  

SciTech Connect

During the previous funding cycle for this project, we investigated the electrochemistry of Cs(I) in air and moisture-stable ionic liquids both with and without the addition of BOBCalixC6. These investigations revealed that the electrochemical windows of the dialkylimidazolium bis[(trifluoromethyl)sulfonyl]imide ionic liquids do not permit the direct electrochemical reduction of Cs(I), even when Hg electrodes are employed, because these organic cations are reduced at less negative potentials than Cs(I). However, Cs(I) coordinated by BOBCalixC6 can be electrolytically reduced to Cs(Hg) in tetraalkylammonium-based room-temperature ionic liquids such as tri-1-butylmethylammonium bis[(trifluoromethyl)sulfonyl]imide (Bu3MeN+Tf2N-) at Hg electrodes. Because this reduction process does not harm either the ionic liquid or the macrocycle, it is a promising method for recycling the cesium extraction system. The previous studies mentioned above were carried out under an inert atmosphere, i.e., in the absence of H2O and O2. However, it may not be economically feasible or even possible to carry out the recycling process in the absence of these contaminants during large-scale processing of aqueous tank waste. Thus, as described in our proposal, we have begun an investigation of the electrochemical recovery of Cs from the Bu3MeN+Tf2N- + BOBCalixC6 extraction system in an air atmosphere containing various amounts of water and oxygen. Our recent preliminary results were very surprising because they indicated that the electrochemical extraction process is relatively insensitive to the presence of small amounts of moisture even when the moisture content of the ionic liquid approaches 1000 ppm. Furthermore, we have found that the ''wet'' ionic liquid can be easily dehydrated under reduced pressure or by sparging with dry nitrogen gas without the need for heat or any other specialized treatment.

Hussey, Charles L.



From molten salts to room temperature ionic liquids: simulation studies on chloroaluminate systems.  


An interaction potential including chloride anion polarization effects, constructed from first-principles calculations, is used to examine the structure and transport properties of a series of chloroaluminate melts. A particular emphasis was given to the study of the equimolar mixture of aluminium chloride with 1-ethyl-3-methylimidazolium chloride, which forms a room temperature ionic liquid EMI+ -AlCl4-. The structure yielded by the classical simulations performed within the framework of the polarizable ion model is compared to the results obtained from entirely electronic structure-based simulations: An excellent agreement between the two flavors of molecular dynamics is observed. When changing the organic cation EMI+ by an inorganic cation with a smaller ionic radius (Li+, Na+, K+), the chloroaluminate speciation becomes more complex, with the formation of Al2Cl7-, in small amounts. The calculated transport properties (diffusion coefficients, electrical conductivity and viscosity) of EMI+ -AlCl4- are in good agreement with experimental data. PMID:22455021

Salanne, Mathieu; Siqueira, Leonardo J A; Seitsonen, Ari P; Madden, Paul A; Kirchner, Barbara



Translation-rotation decoupling and nonexponentiality in room temperature ionic liquids  

SciTech Connect

Using a combination of light scattering techniques and broadband dielectric spectroscopy, we have measured the temperature dependence of structural relaxation time and self diffusion in three imidazolium-based room temperature ionic liquids: [bmim][NTf2], [bmim][PF6], and [bmim][TFA]. A detailed analysis of the results demonstrates that self diffusion decouples from structural relaxation in these systems as the temperature is decreased toward Tg. The degree to which the dynamics are decoupled, however, is shown to be surprisingly weak when compared to other supercooled liquids of similar fragility. In addition to the weak decoupling, we demonstrate that the temperature dependence of the structural relaxation time in all three liquids can be well described by a single Vogel-Fulcher-Tamann function over 13 decades in time from 10 11 s up to 102 s. Furthermore, the stretching of the structural relaxation is shown to be temperature independent over the same range of time scales, i.e., time temperature superposition is valid for these ionic liquids from far above the melting point down to the glass transition temperature.We suggest that these phenomena are interconnected and all result from the same underlying mechanism strong and directional intermolecular interactions.

Griffin, Phillip [University of Tennessee (UTK) and Oak Ridge National Laboratory (ORNL); Agapov, Alexander L [ORNL; Sokolov, Alexei P [ORNL



Translation-rotation decoupling and nonexponentiality in room temperature ionic liquids  

NASA Astrophysics Data System (ADS)

It is generally accepted that room temperature ionic liquids (RTILs) have many characteristics in common with prototypical molecular glass formers. In order to understand the glassy dynamics of RTILs, we have measured the temperature dependence of structural relaxation time and self diffusion in three imidazolium based RTILs. We demonstrate that self diffusion decouples from structural relaxation in these systems as the temperature is decreased toward Tg, but the degree of decoupling is shown to be exceptionally small. In addition to the weak decoupling, we demonstrate that the temperature dependence of structural relaxation time in all three liquids can be well described by a single Vogel-Fulcher-Tammann (VFT) function over 13 decades in time. Furthermore, the stretching of the structural relaxation is shown to be temperature independent over the same range of timescales, i.e. time-temperature superposition is valid for these ionic liquids in the entire temperature range. These properties are at odds with the usual behavior of most ``fragile'' glass forming liquids. We suggest that these differences may result from strong and directional intermolecular interactions characteristic to RTILs.

Griffin, Philip; Agapov, Alexander; Sokolov, Alexei



Layered structure of room-temperature ionic liquids in microemulsions by multinuclear NMR spectroscopic studies.  


Microemulsions form in mixtures of polar, nonpolar, and amphiphilic molecules. Typical microemulsions employ water as the polar phase. However, microemulsions can form with a polar phase other than water, which hold promise to diversify the range of properties, and hence utility, of microemulsions. Here microemulsions formed by using a room-temperature ionic liquid (RTIL) as the polar phase were created and characterized by using multinuclear NMR spectroscopy. (1)H, (11)B, and (19)F?NMR spectroscopy was applied to explore differences between microemulsions formed by using 1-butyl-3-methylimidazolium tetrafluoroborate ([bmim][BF(4)]) as the polar phase with a cationic surfactant, benzylhexadecyldimethylammonium chloride (BHDC), and a nonionic surfactant, Triton X-100 (TX-100). NMR spectroscopy showed distinct differences in the behavior of the RTIL as the charge of the surfactant head group varies in the different microemulsion environments. Minor changes in the chemical shifts were observed for [bmim](+) and [BF(4)](-) in the presence of TX-100 suggesting that the surfactant and the ionic liquid are separated in the microemulsion. The large changes in spectroscopic parameters observed are consistent with microstructure formation with layering of [bmim](+) and [BF(4)](-) and migration of Cl(-) within the BHDC microemulsions. Comparisons with NMR results for related ionic compounds in organic and aqueous environments as well as literature studies assisted the development of a simple organizational model for these microstructures. PMID:21547960

Falcone, R Dario; Baruah, Bharat; Gaidamauskas, Ernestas; Rithner, Christopher D; Correa, N Mariano; Silber, Juana J; Crans, Debbie C; Levinger, Nancy E



Existence of optical phonons in the room temperature ionic liquid 1-ethyl-3-methylimidazolium trifluoromethanesulfonate  

PubMed Central

The technologically important properties of room temperature ionic liquids (RTILs) are fundamentally linked to the ion–ion interactions present among the constituent ions. These ion–ion interactions in one RTIL (1-ethyl-3-methylimidazolium trifluoromethanesulfonate, [C2mim]CF3SO3) are characterized with transmission FTIR spectroscopy and polarized attenuated total reflection (ATR) FTIR spectroscopy. A quasilattice model is determined to be the best framework for understanding the ionic interactions. A novel spectroscopic approach is proposed to characterize the degree of order that is present in the quasilattice by comparing the dipole moment derivative calculated from two independent spectroscopic measurements: (1) the TO–LO splitting of a vibrational mode using dipolar coupling theory and (2) the optical constants of the material derived from polarized ATR experiments. In principle, dipole moment derivatives calculated from dipolar coupling theory should be similar to those calculated from the optical constants if the quasilattice of the RTIL is highly structured. However, a significant disparity for the two calculations is noted for [C2mim]CF3SO3, indicating that the quasilattice of [C2mim]CF3SO3 is somewhat disorganized. The potential ability to spectroscopically characterize the structure of the quasilattice, which governs the long-range ion–ion interactions in a RTIL, is a major step forward in understanding the interrelationship between the molecular-level interactions among the constituent ions of an ionic liquid and the important physical properties of the RTIL. PMID:21476760

Burba, Christopher M.; Frech, Roger



Direct electrochemistry of cytochrome c entrapped in agarose hydrogel in room temperature ionic liquids.  


Direct electrochemistry of cytochrome c (cyt-c) entrapped in agarose hydrogel on gold electrode (Au), edge plane pyrolytic graphite electrode (EPPGE) and glassy carbon electrode (GC) in two room temperature ionic liquids was investigated. The effects of the addition of N,N-dimethylformamide (DMF) in the agarose-cyt-c film, water concentration in ionic liquids and exterior metal ions on the electrochemical behavior of cyt-c were monitored, and electrocatalytic properties of cyt-c were also done. Results showed that a good quasi-reversible redox behavior of cyt-c could be found after adding DMF in agarose-cyt-c film, and peak shape would not change after continuously scanning for 50 cycles. In addition, a certain amount of water in hydrophilic ionic liquids is necessary to maintain electrochemical activities of cyt-c, electrochemical performance of cyt-c is the best when the water content is 5.2% and 5.8% for 1-butyl-3-methylimidazolium bromide ([Bmim][Br]) and 1-butyl-3-methylimidazolium tetrafluoroborate([Bmim][BF(4)]) respectively. However, electrochemical activities of cyt-c are inhibited by exterior metal ions. Interestingly, cyt-c entrapped in agarose hydrogel on EPPGE and GC could catalyze the electroreduction of trichloroacetic acid (TCA) and tert-butyl hydroperoxide (t-BuOOH) in [Bmim][BF(4)], but could not in [Bmim][Br]. Reasons for above-mentioned differences of electrochemical properties of cyt-c in different ionic liquids were preliminarily discussed. PMID:21659008

Wang, Sui; Guo, Zhiyong; Zhang, Huina



Cellulose gels produced in room temperature ionic liquids by ionizing radiation  

NASA Astrophysics Data System (ADS)

Cellulose-based gels were produced in room temperature ionic liquids (RTILs) by ionizing radiation. Cellulose was dissolved at the initial concentration of 20 wt% in 1-ethyl-3-methylimidazolium (EMI)-acetate or N,N-diethyl-N-methyl-N-(2-methoxyethyl)ammonium (DEMA)-formate with a water content of 18 wt%, and irradiated with ?-rays under aerated condition to produce new cellulose gels. The gel fractions of the cellulose gels obtained in EMI-acetate and DEMA-formate at a dose of 10 kGy were 13% and 19%, respectively. The formation of gel fractions was found to depend on the initial concentration of cellulose, water content, and irradiation temperature. The obtained gel readily absorbed water, methanol, ethanol, dichloromethane, N,N-dimethylacetamide, and RTILs.

Kimura, Atsushi; Nagasawa, Naotsugu; Taguchi, Mitsumasa



Free Radical Polymerization of Styrene and Methyl Methacrylate in Various Room Temperature Ionic Liquids  

SciTech Connect

Conventional free radical polymerization of styrene and methyl methacrylate was carried out in various room temperature ionic liquids (RTILs). The RTILs used in this research encompass a wide range of cations and anions. Typical cations include imidazolium, phosphonium, pyridinium, and pyrrolidinium; typical anions include amide, borate, chloride, imide, phosphate, and phosphinate. Reactions are faster and polymers obtained usually have higher molecular weights when compared to polymerizations carried out in volatile organic solvents under the same conditions. This shows that rapid rates of polymerization and high molecular weights are general features of conventional radical polymerizations in RTILs. Attempts to correlate the polarities and viscosities of the RTILs with the polymerization behavior fail to yield discernible trends.

Zhang, Hongwei [University of Tennessee, Knoxville (UTK); Hong, Kunlun [ORNL; Mays, Jimmy [ORNL



Solvent extraction and stripping of silver ions in room-temperature ionic liquids containing calixarenes.  


We found that a calix[4]arene-bearing pyridine is soluble in a typical room-temperature ionic liquid (RTIL), 1-alkyl-3-methylimidazolium hexafluorophosphate. Pyridinocalix[4]arene showed a high extraction ability and selectivity for silver ions. The extraction performance of the calix[4]arene was greatly enhanced by dissolution in RTILs compared to in chloroform. In a competitive extraction test using five different metal ions (Ag+, Cu2+, Zn2+, Co2+, Ni2+), only silver ions were transferred by the calix[4]arene from the aqueous feed phase into the RTILs, through a cation-exchange mechanism. The pyridinocalix[4]arene was found to form a stable 1:1 complex with silver ions, both by slope analysis and by Job's method. Since it is easy to strip silver ions from RTILs by controlling the aqueous-phase pH, the extraction performance of calix[4]arene in RTILs was maintained after five repeated uses. PMID:15373439

Shimojo, Kojiro; Goto, Masahiro



The voltammetry of surface bound 2-anthraquinonyl groups in room temperature ionic liquids: Cation size effects  

NASA Astrophysics Data System (ADS)

A glassy carbon microelectrode has been modified with multilayer films of 2-anthraquinonyl groups (AQ L), and characterised in three different room temperature ionic liquids (RTILs). The electroactivity of the anthraquinonyl films was found to vary with the size of the RTIL cation, in that the extent of the AQLrad -/ AQL2- reduction was found to decrease with increasing cation size. Two distinct one-electron redox waves were observed in RTILs composed of smaller cations, while only a single one-electron wave was observed in RTILs composed of larger cations. It is proposed that complete reduction of the film cannot be achieved using larger RTIL cations, as steric hindrance within the film inhibits charge compensation.

Ernst, Sven; Aldous, Leigh; Compton, Richard G.



Gas?Liquid Interface of Hydrophobic and Hydrophilic Room-Temperature Ionic Liquids and Benzene: Sum Frequency Generation and Surface Tension Studies  

Microsoft Academic Search

Surface investigation of room-temperature ionic liquid and benzene mixtures has been performed using sum frequency generation vibrational spectroscopy and surface tension measurements. Specifically, the study looked into the effect of benzene on the cation orientation of room-temperature ionic liquids at the gas-liquid interface. 1-Butyl-3-methylimidazolium hexafluorophosphate, (BMIM)(PF6) and 1-butyl-3-methylimidazolium tetrafluo- roborate, (BMIM)(BF4) were considered for hydrophobic and hydrophilic ionic liquids, respectively.

Cherry S. Santos; Steven Baldelli



Matrix-enhanced secondary ion mass spectrometry (ME SIMS) using room temperature ionic liquid matrices.  


Room temperature ionic liquids (ILs) have many applications including as matrices in MALDI. We wished to investigate the efficacy of ILs as matrices in time-of-flight secondary ion mass spectrometry and in mass spectrometric imaging (MS imaging). Two ILs derived from alpha-cyano-4-hydroxycinnamic acid (CHCA) were synthesized and tested using phospholipids, cholesterol, and peptides. The molecular ion intensities of 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC), 1,2-dipalmitoyl-sn-glycero-3-phosphoethanolamine (DPPE), cholesterol, and bradykinin were greatly increased using IL matrices. Further, detection limits were also improved: for DPPC and DPPE detection, limits were at least 2 orders of magnitude better using IL matrices. However, these IL matrices were not effective for the enhancement of angiotensin I ions. The data also indicate that IL matrices are suitable for imaging MS. The IL matrices did not cause changes to the sample surface via matrix crystallization or other processes; no "hot spots" were observed in the mass spectra. As a demonstration, an onionskin membrane was imaged. In the matrix-enhanced MS images, ions characteristic of proteins and other biomolecules were observed which could not otherwise be observed. Clearly ionic liquids deserve further investigation in SIMS and MS imaging. PMID:20462181

Fitzgerald, Jennifer J D; Kunnath, Paul; Walker, Amy V



Heats of vaporization of room temperature ionic liquids by tunable vacuum ultraviolet photoionization  

SciTech Connect

The heats of vaporization of the room temperature ionic liquids (RTILs) N-butyl-N-methylpyrrolidinium bistrifluorosulfonylimide, N-butyl-N-methylpyrrolidinium dicyanamide, and 1-butyl-3-methylimidazolium dicyanamide are determined using a heated effusive vapor source in conjunction with single photon ionization by a tunable vacuum ultraviolet synchrotron source. The relative gas phase ionic liquid vapor densities in the effusive beam are monitored by clearly distinguished dissociative photoionization processes via a time-of-flight mass spectrometer at a tunable vacuum ultraviolet beamline (Chemical Dynamics Beamline) at the Advanced Light Source synchrotron facility. Resulting in relatively few assumptions, through the analysis of both parent cations and fragment cations, the heat of vaporization of N-butyl-N-methylpyrrolidinium bistrifluorosulfonylimide is determined to be Delta Hvap(298.15 K) = 195+-19 kJ mol-1. The observed heats of vaporization of 1-butyl-3-methylimidazolium dicyanamide (Delta Hvap(298.15 K) = 174+-12 kJ mol-1) and N-butyl-N-methylpyrrolidinium dicyanamide (Delta Hvap(298.15 K) = 171+-12 kJ mol-1) are consistent with reported experimental values using electron impact ionization. The tunable vacuum ultraviolet source has enabled accurate measurement of photoion appearance energies. These appearance energies are in good agreement with MP2 calculations for dissociative photoionization of the ion pair. These experimental heats of vaporization, photoion appearance energies, and ab initio calculations corroborate vaporization of these RTILs as intact cation-anion ion pairs.

Chambreau, Steven D.; Vaghjiani, Ghanshyam L.; To, Albert; Koh, Christine; Strasser, Daniel; Kostko, Oleg; Leone, Stephen R.



Spectroscopic and photophysical properties of ZnTPP in a room temperature ionic liquid.  


The steady-state absorption and emission spectra and the time-resolved Soret- and Q-band excited fluorescence profiles of the model metalloporphyrin, ZnTPP, have been measured in a highly purified sample of the common room temperature ionic liquid, [bmim][PF?]. S?-S? emission resulting from Soret-band excitation behaves in a manner completely consistent with that of molecular solvents of the same polarizability. The ionic nature of the solvent and its slow solvation relaxation times have no significant effect on the nature of the radiationless decay of the S? state, which decays quantitatively to S? at a population decay rate that is consistent with the weak coupling case of radiationless transition theory (energy gap law). The ratio of the intensities of the Q?:Q? (0-0:1-0) bands is consistent with the solvatochromic shift correlation data obtained for molecular solvents. The temporal S? fluorescence decay profiles measured at a single emission wavelength are biexponential; the longer-lived major component is similar to that observed for ZnTPP in molecular solvents, and the minor shorter-lived component is attributed to solvent relaxation processes on a nanosecond time scale. PMID:20936873

Szmytkowski, Jedrzej; Bond, Toby; Paige, Matthew F; Scott, Robert W J; Steer, Ronald P



The first (ferrocenylmethyl)imidazolium and (ferrocenylmethyl)triazolium room temperature ionic liquids.  


N-(Ferrocenylmethyl)imidazole (3a), 1-(ferrocenylmethyl)-1,2,4-triazole (3b), 1,1'-bis[(1H-imidazol-1-yl)methyl]ferrocene (8a), 1,1'-bis([1H-(2-methyl)imidazol-1-yl]methyl]ferrocene (8b), and 1,1'-bis[(1H-1,2,4-triazol-1-yl)methyl]ferrocene (8c) were synthesized in moderate yields. These compounds were quaternized with methyl iodide to form 1-(ferrocenylmethyl)-3-methylimidazolium iodide (4a), 1-(ferrocenylmethyl)-4-methyl-1,2,4-triazolium iodide (4b), 1,1'-bis([1-(2,3-dimethyl)imidazolium]methyl)ferrocene diiodide (9b), and 1,1'-bis([1-(4-methyl)-1,2,4-triazolium]methyl)ferrocene diiodide (9c), respectively, in excellent yields. Compounds 4a, 4b, 9b, and 9c were metathesized with bis(trifluoromethanesulfonyl)amide to give high yields of 5a, 5b, 10b, and 10c. With potassium hexafluorophosphate, 9b forms 10d. Salts 5a, 5b, and 10c are the first room-temperature ionic liquids with cations containing an organometallic moiety that exhibit T(g) values well below room temperature, i.e., -32, -16, and -11 degrees C. The compounds were characterized by (1)H, (19)F, and (13)C NMR, MS, and elemental analyses. T(g) values and melting points were determined by DSC. T(d) values (5% weight loss temperature) were recorded by TGA. X-ray single-crystal structures show that 9c and 10d crystallize in the triclinic space group P. PMID:15154802

Gao, Ye; Twamley, Brendan; Shreeve, Jean'ne M



Interaction of gelatin with room temperature ionic liquids: a detailed physicochemical study.  


Interaction of gelatin (G) with room temperature ionic liquids (ILs), 3-methyl-1-octylimidazolium chloride [C(8)mim][Cl] and 1-butyl-3-methylimidazolium octylsulfate [C(4)mim][C(8)OSO(3)], have been investigated through tensiometry, conductivity, steady-state fluorescence, turbidity, and dynamic light scattering (DLS). We have observed that the nature of interactions in G-[C(8)mim][Cl] system are remarkably different as compared to G-[C(4)mim][C(8)OSO(3)] system. At low concentrations, much below the critical micelle concentration (cmc) of IL, the IL monomers are adsorbed at the native G at the interface forming G-IL (monomer) complex, whereas both the monomers and lower IL aggregates are interacted with G in bulk leading to G-IL (aggregate) complex. The increased hydrophobic character of the G-IL complexes is evidenced from pyrene fluorescence. Turbidity measurements showed interestingly distinguished coacervation characteristics in the investigated systems. In case of G-[C(4)mim][C(8)OSO(3)] system, the coacervates dissolve in the free micellar solution whereas G-[C(8)mim][Cl] coacervates remain stable up to very high concentration. DLS provided useful information about the changes in size of gelatin and the nature of interactions between gelatin and ILs. Thermodynamic parameters of micellization with and without gelatin have been derived and compared. PMID:20527871

Singh, Tejwant; Boral, Shilpi; Bohidar, H B; Kumar, Arvind



Hydrogen-bonding interactions and protic equilibria in room-temperature ionic liquids containing crown ethers.  

SciTech Connect

Nuclear magnetic resonance (NMR) spectroscopy has been used to study hydrogen-bonding interactions between water, associated and dissociated acids (i.e., nitric and methanesulfonic acids), and the constituent ions of several water-immiscible room-temperature ionic liquids (ILs). In chloroform solutions also containing a crown ether (CE), water molecules strongly associate with the IL ions, and there is rapid proton exchange between these bound water molecules and hydronium associated with the CE. In neat ILs, the acids form clusters differing in their degree of association and ionization, and their interactions with the CEs are weak. The CE can either promote proton exchange between different clusters in IL solution when their association is weak or inhibit such exchange when the association is strong. Even strongly hydrophobic ILs are shown to readily extract nitric acid from aqueous solution, typically via the formation of a 1:1:1 {l_brace}H{sub 3}O{sup +} {center_dot} CE{r_brace}NO{sub 3}{sup -} complex. In contrast, the extraction of methanesulfonic acid is less extensive and proceeds mainly by IL cation-hydronium ion exchange. The relationship of these protic equilibria to the practical application of hydrophobic ILs (e.g., in spent nuclear fuel reprocessing) is discussed.

Marin, T.; Shkrob, I.; Dietz, M. (Chemical Sciences and Engineering Division); (Benedictine Univ.); (Univ. of Wisconsin at Milwaukee)



Effects of Room-Temperature Ionic Liquids on Freshwater Primary Producers  

NASA Astrophysics Data System (ADS)

Room-temperature ionic liquids (ILs) are non-volatile chemicals, which are presumed to be environmentally friendly because they pose no significant threat to air quality. However, the potential toxic effects of ILs on aquatic environments have not been studied, despite the likelihood of unintentional releases into streams and lakes during industrial applications. We studied the effects of ILs on the growth rates of the freshwater green algae Scenedesmus quadricauda and Chlamydomonas reinhardtii in 96-h bioassays. ILs with increasing alkyl chain lengths (from 1-butyl- to 1-hexyl- to 1-octyl-3-methylimidazolium bromide) were increasingly toxic to S. quadricauda (EC-50 values of 0.28 mg*L-1, 0.04 mg*L-1, and <0.005 mg*L-1 respectively). S. quadricauda growth rates decreased with increasing IL concentration across all treatments. Compared to controls, C. reinhardtii growth rates were higher at 200-800 mg*L-1 1-butyl-3-methylimidazolium bromide (bmimBr) treatments, but declined at 1600 mg*L-1 bmimBr. These results illustrate that different algal taxa can respond quite differently to potential chemical pollutants. Furthermore, by studying the effects of ILs on primary producers in concert with organisms from other trophic levels, we can develop hypotheses about how these effects may be felt throughout aquatic ecosystems.

Kulacki, K. J.; Bernot, R. J.; Lamberti, G. A.; Lodge, D. M.



Interaction of imidazolium-based room-temperature ionic liquids with DOPC phospholipid monolayers: electrochemical study.  


To test the biocompatible character of room-temperature ionic liquids (ILs), the interaction of various ILs with biological membrane (biomembrane) models was studied in this work. Dioleoyl phosphatidylcholine (DOPC) adsorbed on a mercury (Hg) electrode forms an impermeable defect-free monolayer which is a well established biomembrane model, prone to be studied by electrochemical techniques. We have monitored the modifications of the Hg supported monolayer caused by ILs using rapid cyclic voltammetry (RCV), alternating current voltammetry (ACV), and electrochemical impedance spectroscopy (EIS). A series of imidazolium-based ILs were investigated whose interaction highlighted the role of anion and lateral side chain of cation during the interaction with DOPC monolayers. It was shown that the hydrophobic and lipophilic character of the IL cations is a primary factor responsible for this interaction. Hg-supported monolayers provide an accurate analysis of the behavior of ILs at the interface of a biomembrane leading to a comprehensive understanding of the interaction mechanisms involved. At the same time, these experiments show that the Hg-phospholipid model is an effective toxicity sensing technique as shown by the correlation between literature in vivo toxicity data and the data from this study. PMID:23654287

Galluzzi, Massimiliano; Zhang, Shengwen; Mohamadi, Shahrzad; Vakurov, Alexander; Podestà, Alessandro; Nelson, Andrew



Free radical (co)polymerization of methyl methacrylate and styrene in room temperature ionic liquids  

NASA Astrophysics Data System (ADS)

Conventional free radical polymerizations were carried out in a variety of room temperature ionic liquids (RTILs). Generally, methyl methacrylate (MMA) and styrene (St) were used as typical monomers to compare the polymerization behavior both in RTILs and in common volatile organic compound solvents (VOCs). In most cases, it was observed that both yields and molecular weights are enhanced in the RTIL. While we believe the "diffusion-controlled termination" mechanism makes the termination of the radical propagating chains difficult due to the highly viscous nature of RTIL, other researchers have suggested that the rapid polymerization rates are due to the high polarity of these reaction media. By employing more than a dozen RTILs with a wide range of anions and cations, we attempted to correlate the viscosity and polarity of the RTILs with the molecular weights and polymerization rates. This correlation was not successful, suggesting that other parameters may also play a role in affecting the polymerization behavior. Other kinds of polymerizations have also been attempted including nitroxide-mediated living radical polymerizations of St and MMA in 1-butyl-3-methylimidazolium hexafluorophosphate ([BMIM]PF6), and redox initiation system initiated polymerization of MMA through redox pair formed by cation of trihexyl-tetradecyl-phosphonium bis(2,4,4-trimethylpentyl) phosphinate ([H3TDP] [(PM3) 2P]) and BPO. The formation of PSt-b-PMMA by sequential monomer addition through the standard free radical polymerization mechanism, using BPO as initiator, can be realized in [BMIM]PF6 due to the insolubility of polymerized first block---PSt in [BMIM]PF6. The macroradicals wrapped inside the chain coils have prolonged lifetimes because of the diminished termination, which allow some of these radicals to initiate polymerization of MMA at room temperature to form diblock copolymer. Solvents effects on reactivity ratios for free radical statistical copolymerization have been observed on comparing reactivity ratios in [BMIM]PF6 to those in common organic solvents such as benzene. The calculated reactivity ratios of St and MMA in [BMIM]PF6 by a non-linear method (CONTOUR computer program) are significantly different from those in benzene at 60°C. The "boot-strap" model, polarity of the solvents, interactions between solvent and monomers (e.g. solvent-monomer complex), viscosity and system heterogeneity all possibly contribute to the difference of the reactivity ratios in RTILs and in benzene.

Zhang, Hongwei


Electrolytic conductivity of four imidazolium-based room-temperature ionic liquids and the effect of a water impurity  

Microsoft Academic Search

The electrolytic conductivities (?) of four hydrophobic room-temperature ionic liquids (RTILs) were measured at temperatures from (288.15 to 323.15)K. The measurements were made with a commercial conductivity cell with platinum black electrodes. In order to exclude atmospheric moisture, the conductivity cell was modified so that it could be sealed during measurements. The RTILs studied were 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide, 1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide, 1-hexyl-3-methylimidazolium

Jason A. Widegren; Eric M. Saurer; Kenneth N. Marsh; Joseph W. Magee



A study on the ultrasonic preparation of nanocrystalline zinc oxide in room temperature ionic liquid and triethylene glycol  

Microsoft Academic Search

A fast and green approach has been developed for the preparation of nanocrystalline zinc oxide (ZnO) in room-temperature ionic liquid (RTIL) via ultrasonic irradiation. For comparison, ZnO nanoparticles have been prepared under the same experimental condition in triethylene glycol (TEG). The results show that ZnO nanorods can be prepared in RTIL, while spherical nanoparticles are obtained in TEG. A possible

Hao Yang; Hai-yan Wang; Yue-tao Yang; Xiao-jun Liu; Shu-yi Zhang



Conventional free radical polymerization in room temperature ionic liquids: a green approach to commodity polymers with practical advantages.  


Free-radical polymerization of methyl methacrylate and styrene using conventional organic initiators in the room temperature ionic liquid, 1-butyl-3-methylimidazolium hexafluorophosphate ([C4mim][PF6]) is rapid and produces polymers with molecular weights up to 10x higher than from benzene; both polymerization and isolation of products were achieved without using VOCs, offering economic as well as environmental advantages. PMID:12125559

Hong, Kunlun; Zhang, Hongwei; Mays, Jimmy W; Visser, Ann E; Brazel, Christopher S; Holbrey, John D; Reichert, W Matthew; Rogers, Robin D



Catalysed esterifications in room temperature ionic liquids with acidic counteranion as recyclable reaction media  

Microsoft Academic Search

Esterification reactions of acetic acid, methoxyacetic acid and methylmalonic acid with neo-pentanol, hexanol, heptanol and decanol have been investigated in three ionic liquids with hydrogen sulphate, dihydrogen phosphate as counteranions and also two ionic liquids modified with HPF6 as catalyst. The nature of both the counteranion and cation influence the behavior of the catalyst. Good yields and high selectivities were

Joan Fraga-Dubreuil; Khadidja Bourahla; Mustapha Rahmouni; Jean Pierre Bazureau; Jack Hamelin



Dynamics of isolated water molecules in a sea of ions in a room temperature ionic liquid.  


The vibrational dynamics of the antisymmetric and symmetric stretching modes of very low concentration spatially isolated D(2)O molecules in the room temperature ionic liquid (RTIL) 1-butyl-3-methylimidazolium hexafluorophosphate (BmImPF(6)) were examined using two-dimensional infrared (2D IR) vibrational echo spectroscopy and infrared pump-probe experiments. In BmImPF(6), D(2)O's antisymmetric and symmetric stretching modes are well resolved in the IR absorption spectrum in spite of the fact that the D(2)O is surrounded by a sea of ions, making it is possible to study inter- and intramolecular dynamics. Both population exchange between the modes and excited-state relaxation to the ground state contribute to the population dynamics. The kinetics for the incoherent population exchange (scattering) between the two modes was determined by the time dependence of the exchange peaks in the 2D IR spectrum. In addition, coherent quantum beats were observed at short time in both the amplitudes and 2D IR band shapes of the modes. The quantum beat decay is caused by dephasing due to both inhomogeneous and homogeneous broadening of the spectral lines. Analysis of the oscillations of the 2D line shapes demonstrates that there is some degree of anticorrelation in the inhomogeneous broadening of the two modes. It is proposed that a distribution in the coupling strength between the local modes that give rise to symmetric and antisymmetric eigenstates is responsible for the anticorrelation. Spectral diffusion, caused by structural evolution of the medium, occurs on multiple time scales and is identical for the two modes within experimental error. The spectral diffusion is fast compared to the time scale for complete orientational randomization of the RTIL. Spectral diffusion of the OD stretch of HOD in BmImPF(6) was also measured, and is essentially the same as that of the D(2)O modes. Orientational anisotropy measurements of HOD in BmImPF(6) determined the orientational relaxation dynamics of the isolated HOD molecules. PMID:23276306

Wong, Daryl B; Giammanco, Chiara H; Fenn, Emily E; Fayer, Michael D




SciTech Connect

The DoE/NE underground storage tanks at Hanford, SRS, and INEEL contain liquid wastes with high concentrations of radioactive species, mainly 137Cs and 90Sr. Because the other components of the liquid waste are mainly sodium nitrate and sodium hydroxide, most of this tank waste can be treated inexpensively as low-level waste if 137Cs and 90Sr can be selectively removed. Many ionophores (crown ether and calixarene compounds) have been synthesized for the purpose of selectively extracting Cs+ and Sr2+ from an aqueous phase into an immiscible organic phase. Recent studies conducted at ORNL1,2 reveal that hydrophobic ionic liquids might be better solvents for extracting metal ions from aqueous solutions with these ionophores than conventional immiscible organic solvents, such as benzene, toluene, and dichloromethane, because both Cs+ and Sr2+ exhibit larger distribution coefficients in the ionic liquids. In addition, the vapor pressures of these ionic liquids are insignificant. Thus, there is little or no vaporization loss of these solvents. Most of the ionic liquids under investigation are relatively nontoxic compared to the hydrocarbon solvents that they replace, classifying them as ''green'' solvents.

Hussey, Charles L.



Electrodeposition of platinum nanoparticles in a room-temperature ionic liquid.  


The electrochemistry of the [PtCl(6)](2-)-[PtCl(4)](2-)-Pt redox system on a glassy carbon (GC) electrode in a room-temperature ionic liquid (RTIL) [i.e., N,N-diethyl-N-methyl-N-(2-methoxyethyl)ammonium tetrafluoroborate (DEMEBF(4))] has been examined. The two-step four-electron reduction of [PtCl(6)](2-) to Pt, i.e., reduction of [PtCl(6)](2-) to [PtCl(4)](2-) and further reduction of [PtCl(4)](2-) to Pt, occurs separately in this RTIL in contrast to the one-step four-electron reduction of [PtCl(6)](2-) to Pt in aqueous media. The cathodic and anodic peaks corresponding to the [PtCl(6)](2-)/[PtCl(4)](2-) redox couple were observed at ca. -1.1 and 0.6 V vs a Pt wire quasi-reference electrode, respectively, while those observed at -2.8 and -0.5 V were found to correspond to the [PtCl(4)](2-)/Pt redox couple. The disproportionation reaction of the two-electron reduction product of [PtCl(6)](2-) (i.e., [PtCl(4)](2-)) to [PtCl(6)](2-) and Pt metal was also found to occur significantly. The electrodeposition of Pt nanoparticles could be carried out on a GC electrode in DEMEBF(4) containing [PtCl(6)](2-) by holding the potential at -3.5 or -2.0 V. At -3.5 V, the four-electron reduction of [PtCl(6)](2-) to Pt can take place, while at -2.0 V the two-electron reduction of [PtCl(6)](2-) to [PtCl(4)](2-) occurs. The results obtained demonstrate that the electrodeposition of Pt at -3.5 V may occur via a series of reductions of [PtCl(6)](2-) to [PtCl(4)](2-) and further [PtCl(4)](2-) to Pt and at -2.0 V via a disproportionation reaction of [PtCl(4)](2-) to [PtCl(6)](2-) and Pt. Furthermore, the deposition potential of Pt nanoparticles was found to largely influence their size and morphology as well as the relative ratio of Pt(110) and Pt(100) crystalline orientation domains. The sizes of the Pt nanoparticles prepared by holding the electrode potential at -2.0 and -3.5 V are almost the same, in the range of ca. 1-2 nm. These small nanoparticles are "grown" to form bigger particles with different morphologies: In the case of the deposition at -2.0 V, the GC electrode surface is totally, relatively compactly covered with Pt particles of relatively uniform size of ca. 10-50 nm. On the other hand, in the case of the electrodeposition at -3.5 V, small particles of ca. 50-100 nm and the grown-up particles of ca. 100-200 nm cover the GC surface irregularly and coarsely. Interestingly, the Pt nanoparticles prepared by holding the potential at -2.0 and -3.5 V are relatively enriched in Pt(100) and Pt(110) facets, respectively. PMID:21995596

Zhang, Da; Chang, Wan Cheng; Okajima, Takeyoshi; Ohsaka, Takeo



NOvel Fission Product Separation Based on Room-Temperature Ionic liquids  

SciTech Connect

The effective extraction of Cs+ and Sr2+ into a relatively new and heretofore untested hydrophobic ionic liquid, tri-n-butylmethylammonium bis[(trifluoromethyl)sulfonyl]imide was demonstrated with calix[4]arene-bis(tert-octylbenzo-crown-6) and dicyclohexano-18-crown-6, respectively. The coordinated Cs+ and Sr2+ were subsequently removed from the ionic liquid extraction solvent by an electrochemical reduction process carried out at mercury electrodes. This process is non-destructive, permitting the ionic liquid and ionophores to be recycled. Although the process is based on mercury electrodes, this is a benefit rather than a detriment because the liquid mercury containing the Cs and Sr can be easily transported to another electrochemical cell where the Cs and Sr could be electrochemically recovered from the mercury amalgam and concentrated into a minimum volume of water or some other inexpensive solvent. This should facilitate the development of a suitable waste form for the extracted Cs+ and Sr2+. Thus, the feasibility of the proposed ionic liquid-based extraction cycle for the removal of 137Cs+ and 90Sr2+ from simulated aqueous tank waste was demonstrated.

Hussey, Charles L.



Phase behavior of CO2 in room-temperature ionic liquid 1-ethyl-3-ethylimidazolium acetate.  


Carbon dioxide solubility (vapor-liquid equilibria: VLE) in an ionic liquid, 1-ethyl-3-ethylimidazolium acetate ([eeim][Ac]) was measured using a gravimetric microbalance at four isotherms (about 283, 298, 323, and 348 K) up to about 2 MPa. An equation-of-state (EOS) model was used to analyze the VLE data and has predicted vapor-liquid-liquid equilibria (VLLE: or liquid-liquid separations) in CO(2)-rich solutions. The VLLE prediction was confirmed experimentally using a volumetric method and likely the liquid-liquid equilibria will intersect with the solid-liquid equilibria such that no lower critical solution temperature can exist and the binary system may be classified as Type III phase behavior. Carbon dioxide solubility in the ionic-liquid-rich solution show extremely unusual behavior. CO(2) dissolves in the ionic liquid at large concentrations (up to about 20 mole % of CO(2)) with almost no vapor pressure above the mixtures. This result is similar to our previous findings with 1-butyl-3-methylimidazolium acetate ([bmim][Ac]) and 1-ethyl-3-methylimidazolium acetate ([emim][Ac]). In all three cases the CO(2) forms a molecular complex (or chemical reaction) with the ionic liquid. (13)C NMR spectroscopy has identified the structure for CO(2) absorbed in [eeim][Ac] to be [eeim]-2-carboxylate. Addition of water to the carboxylate leads to the dissolution of CO(2). The thermodynamic excess properties (enthalpy, entropy, and Gibbs energy) for all three systems have been calculated using the EOS and support the complex formation of the type AB(2) (where A is CO(2) and B is ionic liquid). Isothermal differential scanning calorimetry has verified the heat of reaction calculations and found for CO(2) absorbing in [emim][Ac], [eeim][Ac] and [bmim][Ac] to be about -38 kJ mol(-1). Additional experiments have examined the effect of water on the density, viscosity and CO(2) solubility in [eeim][Ac] and the CO(2) solubility in mixtures of [eeim][Ac] with other acetate salts. PMID:22511252

Shiflett, Mark B; Elliott, Beth A; Lustig, Steve R; Sabesan, Subramaniam; Kelkar, Manish S; Yokozeki, A




EPA Science Inventory

Ionic liquids (ILs) have been shown to be a newer medium for a wide variety of chemical reactions and are considered as the potential replacements for traditional volatile organic solvents. However, the separation and recovery of organic compounds from ILs has not been systematic...



EPA Science Inventory

The objectives of this project are (a) to synthesize new ionic liquids tailored for the extractive separation of Cs + and Sr 2+; (b) to select optimum macrocyclic extractants through studies of complexation of fission products with macrocyclic extractants and transport in new ext...


Novel Fission-Product Separation based on Room-Temperature Ionic Liquids  

SciTech Connect

U.S. DOE's underground storage tanks at Hanford, SRS, and INEEL contain liquid wastes with high concentrations of radioactive cesium-137 and strontium-90. Because the primary chemical components of alkaline supernatants are sodium nitrate and sodium hydroxide, the majority of this could be disposed of as low level waste if radioactive cesium-137 and strontium- 90 could be selectively removed. The underlying goal of this project was to investigate the application of ionic liquids as novel solvents for new solvent extraction processes for separation of cesium-137 and strontium-90 from tank wastes. Ionic liquids are a distinct sub-set of liquids, comprising only of cations and anions they are proving to be increasingly interesting fluids for application in systems from electrochemistry to energetic materials, and are also rapidly establishing their promise as viable media for synthesis and separations operations. Properties including low melting points, electrochemical conductivity, wide liquid ranges, lack of vapor-pressure, and chemical tunability have encouraged researchers to explore the uses of ILs in place of volatile organic solvents. The most promising current developments arise from control of the unique combinations of chemical and physical properties characteristic of ionic liquids.

Rogers, Robin D.



Electrochemistry and spectroscopy of electrolytes and cathode materials in room-temperature ionic liquids  

NASA Astrophysics Data System (ADS)

The demonstration of a stable, reversible, alkali metal anode is an important step in the development of practical secondary batteries using room temperature chloroaluminate molten salts as electrolytes. Such melts are made by mixing 1-ethyl-3-methylimidazolium chloride (EMIC) with aluminum chloride, and can be Lewis buffered by adding LiCl or NaCl. It has been shown previously that protons added to a sodium chloride buffered melt as 1-ethyl-3-methyfimidazolium hydrogen dichloride (EMIHCl2) provide a more negative voltage window and nearly reversible deposition-stripping behavior for sodium. It is reported here that triethanolamine hydrogen chloride is effective in widening the voltage window, allows the plating and stripping of both lithium and sodium, and is stable in buffered EMIC/AlCl3 melts for months. It is suggested that deprotonation of one ethanolic group of triethanolamine HCl is responsible for the effect. The electrochemistry and UV-visible spectroscopy of several vanadium oxides have been examined in room temperature melts. By varying the mole ratio of the two components, Lewis basic, neutral and acidic melts were made. Most oxides have very low solubility: V2O4 and V2O3 are insoluble and V2O5 has a solubility limit less than 5 mM, but the solubilities of the salts NaVO 3, Na3VO4, and NH4VO3, VOCl 3 and VOF3 are significantly higher. The electrochemistry of V2O5, NaVO3, Na3VO4, NH4VO3, VOCl3 and VOF3 is similar in neutral and acidic melts. In the neutral melt each compound shows an irreversible reduction at about 0.45V vs. an Al wire reference electrode. In an acidic melt (mole fraction AlCl3 = 0.55) each of these compounds exhibit additional reduction peaks at more positive potentials. Coulometric and spectroscopic data for the 0.45V reduction suggest that mixed oxidation state polyvanadates may be formed. Controlled potential coulometry demonstrated that the reduction at 0.45V was the reduction of V(V) to V(IV) and the more positive reduction peaks were caused by the reduction of some other species of V(V) present in the acidic melts. New room temperature melts have been prepared by mixing Lewis acidic, VOCl3, with Lewis basic, EMIC. The new melts are dark red homogeneous liquids that are very conductive and easily reduced.

Ryan, David Martin


Solubility of CO2 in room temperature ionic liquid [hmim][Tf2N].  


Solubility measurements of carbon dioxide in 1-hexyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide have been performed with a gravimetric microbalance at temperatures of about 282, 297, 323, and 348 K and pressures up to about 2 MPa. Two different sources for the ionic liquid are examined in this work: an ultrapure sample from NIST (the IUPAC task force sample) and a commercially available sample. Both samples show nearly identical solubility behaviors, being undistinguishable within experimental uncertainties. Solubility (pressure-temperature-composition) data have been well correlated with an equation-of-state (EOS) model used in our previous works. The EOS model calculations are compared with experimental solubility data for the same system in the literature. The present EOS has predicted partial immiscibility at the CO2-rich side solutions. To prove this prediction, vapor-liquid-liquid equilibrium experiments have been made, and our predictions have been confirmed. PMID:17266362

Shiflett, Mark B; Yokozeki, A



Pressure-induced frustration-frustration process in 1-butyl-3-methylimidazolium hexafluorophosphate, a room-temperature ionic liquid.  


We have found that the room-temperature ionic liquid (RTIL) reveals outstanding pressure-induced phase changes from a liquid state to a crystal polymorph and finally to a glass form upon compression by up to 8 GPa. The RTIL is 1-butyl-3-methylimidazolium hexafluorophosphate, [C4mim][PF6], which offers the opportunity to investigate a variety of fluctuations in one system and can be completely recovered without dissociation or polymerization, even after decompression. Similar to charge frustration, spin ice-like frustration, and geometric frustration in high potential spintronics/multiferroic materials, the RTIL frustrations are classified into charge (scalar), orientation (vector), and coordination number (topology). Degrees of freedom at each state of [C4mim][PF6] are described by charge balancing, molecular orientational order/disorder, molecular conformations of the C4mim(+) cation, and the coordination number. Here, we show a novel "conformation glass" induced by high pressure. PMID:24358982

Abe, Hiroshi; Takekiyo, Takahiro; Hatano, Naohiro; Shigemi, Machiko; Hamaya, Nozomu; Yoshimura, Yukihiro



Selected chemical-physical properties and structural heterogeneities in 1-ethyl-3-methylimidazolium alkyl-sulfate room temperature ionic liquids  

NASA Astrophysics Data System (ADS)

Here we report on the temperature dependence of the density and refractive index of alkyl-sulfate room temperature ionic liquids (RTIL): 1-ethyl-3-methylimidazolium n-alkyl-sulfate, [C 2mim][C nOSO 3] ( n = 2, 4, 6, 8). Moreover an X-ray scattering structural study on the salts' morphology is presented, highlighting the existence of nano-scale structural heterogeneities, whose size depends linearly on the anion alkyl chain length. This behaviour was observed in other RTILs and is related to nano-scale alkyl chains' segregation into a charged network. This study shows differences between alkyl-sulfate salts and other RTILs, providing new indication for further tuning the RTILs' properties by wise modification of chemical architecture.

Russina, Olga; Gontrani, Lorenzo; Fazio, Barbara; Lombardo, Domenico; Triolo, Alessandro; Caminiti, Ruggero



Highly efficient extraction of phenolic compounds by use of magnetic room temperature ionic liquids for environmental remediation.  


A hydrophobic magnetic room temperature ionic liquid (MRTIL), trihexyltetradecylphosphonium tetrachloroferrate(III) ([3C(6)PC(14)][FeCl(4)]), was synthesized from trihexyltetradecylphosphonium chloride and FeCl(3) · 6H(2)O. This MRTIL was investigated as a possible separation agent for solvent extraction of phenolic compounds from aqueous solution. Due to its strong paramagnetism, [3C(6)PC(14)][FeCl(4)] responds to an external neodymium magnet, which was employed in the design of a novel magnetic extraction technique. The conditions for extraction, including extraction time, volume ratio between MRTIL and aqueous phase, pH of aqueous solution, and structures of phenolic compounds were investigated and optimized. The magnetic extraction of phenols achieved equilibrium in 20 min and the phenolic compounds were found to have higher distribution ratios under acidic conditions. In addition, it was observed that phenols containing a greater number of chlorine or nitro substituents exhibited higher distribution ratios. For example, the distribution ratio of phenol (D(Ph)) was 107. In contrast, 3,5-dichlorophenol distribution ratio (D(3,5-DCP)) had a much higher value of 6372 under identical extraction conditions. When compared with four selected traditional non-magnetic room temperature ionic liquids, our [3C(6)PC(14)][FeCl(4)] exhibited significantly higher extraction efficiency under the same experimental conditions used in this work. Pentachlorophenol, a major component in the contaminated soil sample obtained from a superfund site, was successfully extracted and removed by use of [3C(6)PC(14)][FeCl(4)] with high extraction efficiency. Pentachlorophenol concentration was dramatically reduced from 7.8 ?g mL(-1) to 0.2 ?g mL(-1) after the magnetic extraction by use of [3C(6)PC(14)][FeCl(4)]. PMID:21783320

Deng, Ning; Li, Min; Zhao, Lijie; Lu, Chengfei; de Rooy, Sergio L; Warner, Isiah M



Vibrational energy relaxation of a diatomic molecule in a room-temperature ionic liquid  

NASA Astrophysics Data System (ADS)

Vibrational energy relaxation (VER) dynamics of a diatomic solute in ionic liquid 1-ethyl-3-methylimidazolium hexafluorophosphate (EMI+PF6-) are studied via equilibrium and nonequilibrium molecular dynamics simulations. The time scale for VER is found to decrease markedly with the increasing solute dipole moment, consonant with many previous studies in polar solvents. A detailed analysis of nonequilibrium results shows that for a dipolar solute, dissipation of an excess solute vibrational energy occurs almost exclusively via the Lennard-Jones interactions between the solute and solvent, while an oscillatory energy exchange between the two is mainly controlled by their electrostatic interactions. Regardless of the anharmonicity of the solute vibrational potential, VER becomes accelerated as the initial vibrational energy increases. This is attributed primarily to the enhancement in variations of the solvent force on the solute bond, induced by large-amplitude solute vibrations. One interesting finding is that if a time variable scaled with the initial excitation energy is employed, dissipation dynamics of the excess vibrational energy of the dipolar solute tend to show a universal behavior irrespective of its initial vibrational state. Comparison with water and acetonitrile shows that overall characteristics of VER in EMI+PF6- are similar to those in acetonitrile, while relaxation in water is much faster than the two. It is also found that the Landau-Teller theory predictions for VER time scale obtained via equilibrium simulations of the solvent force autocorrelation function are in reasonable agreement with the nonequilibrium results.

Shim, Youngseon; Kim, Hyung J.



Emission-based optical carbon dioxide sensing with HPTS in green chemistry reagents: room-temperature ionic liquids.  


We describe the characterization of a new optical CO(2) sensor based on the change in the fluorescence signal intensity of 8-hydroxypyrene-1,3,6-trisulfonic acid trisodium salt (HPTS) in green chemistry reagents--room-temperature ionic liquids (RTILs). As far as we are aware, this is the first time RTILs, 1-methyl-3-butylimidazolium tetrafluoroborate (RTIL-I) and 1-methyl-3-butylimidazolium bromide (RTIL-II), have been used as matrix materials with HPTS in an optical CO(2) sensor. It should be noted that the solubility of CO(2) in water-miscible ionic liquids is approximately 10 to 20 times that in conventional solvents, polymer matrices, or water. The response of the sensor to gaseous and dissolved CO(2) has been evaluated. The luminescence intensity of HPTS at 519 and 521 nm decreased with the increasing concentrations of CO(2) by 90 and 75% in RTIL-I and RTIL-II, respectively. The response times of the sensing reagents were in the range 1-2 min for switching from nitrogen to CO(2), and 7-10 min for switching from CO(2) to nitrogen. The signal changes were fully reversible and no significant hysteresis was observed during the measurements. The stability of HPTS in RTILs was excellent and when stored in the ambient air of the laboratory there was no significant drift in signal intensity after 7 months. Our stability tests are still in progress. PMID:16896616

Oter, Ozlem; Ertekin, Kadriye; Topkaya, Derya; Alp, Serap



Growth of silicon nanowires of controlled diameters by electrodeposition in ionic liquid at room temperature.  


Silicon nanowires were fabricated for the first time by electrochemical template synthesis at room temperature. This innovative, cheap, and simple process consists of electroreduction of Si ions using a nonaqueous solvent and insulating nanoporous membranes with average pore diameters from 400 to 15 nm which fix the nanowires diameters. Characterization techniques such as scanning and transmission electron microscopies, infrared absorption measurements, X-ray diffraction experiments, energy dispersive X-ray, and Raman spectrometries show that the as-deposited silicon nanowires are amorphous, composed of pure Si and homogeneous in sizes with average diameters and lengths well matching with the nanopores' diameters and the thicknesses of the membranes. Thanks to annealing treatments, it is possible to crystallize the Si nanowires, demonstrating the potentiality for this innovative electrochemical process to obtain a wide range of Si nanowires with well controlled diameters and lengths. PMID:18788792

Mallet, J; Molinari, M; Martineau, F; Delavoie, F; Fricoteaux, P; Troyon, M



Room temperature ionic liquids enhanced the speciation of Cr(VI) and Cr(III) by hollow fiber liquid phase microextraction combined with flame atomic absorption spectrometry.  


A new method for the speciation of Cr(VI) and Cr(III) based on enhancement effect of room temperature ionic liquids (RTILs) for hollow fiber liquid phase microextraction (HF-LPME) combined with flame atomic absorption spectrometry (FAAS) was developed. Room temperature ionic liquids (RTILs) and diethyldithiocarbamate (DDTC) were used enhancement reagents and chelating reagent, respectively. The addition of room temperature ionic liquids led to 3.5 times improvement in the determination of Cr(VI). In this method, Cr(VI) reacts with DDTC yielding a hydrophobic complex, which is subsequently extracted into the lumen of hollow fiber, whereas Cr(III) is remained in aqueous solutions. The extraction organic phase was injected into FAAS for the determination of Cr(VI). Total Cr concentration was determined after oxidizing Cr(III) to Cr(VI) in the presence of KMnO(4) and using the extraction procedure mentioned above. Cr(III) was calculated by subtracting of Cr(VI) from the total Cr. Under optimized conditions, a detection limit of 0.7 ng mL(-1) and an enrichment factor of 175 were achieved. The relative standard deviation (RSD) was 4.9% for Cr(VI) (40 ng mL(-1), n=5). The proposed method was successfully applied to the speciation of chromium in natural water samples with satisfactory results. PMID:22981284

Zeng, Chujie; Lin, Yao; Zhou, Neng; Zheng, Jiaoting; Zhang, Wei



The electrochemical reduction of the purines guanine and adenine at platinum electrodes in several room temperature ionic liquids.  


The reduction of guanine was studied by microelectrode voltammetry in the room temperature ionic liquids (RTILs) N-hexyltriethylammonium bis (trifluoromethanesulfonyl) imide [N(6,2,2,2)][N(Tf)(2)], 1-butyl-3-methylimidazolium hexafluorosphosphate [C(4)mim][PF(6)], N-butyl-N-methyl-pyrrolidinium bis(trifluoromethanesulfonyl)imide [C(4)mpyrr][N(Tf)(2)], 1-butyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide [C(4)mim][N(Tf)(2)], N-butyl-N-methyl-pyrrolidinium dicyanamide [C(4)mpyrr][N(NC)(2)] and tris(P-hexyl)-tetradecylphosphonium trifluorotris(pentafluoroethyl)phosphate [P(14,6,6,6)][FAP] on a platinum microelectrode. In [N(6,2,2,2)][NTf(2)] and [P(14,6,6,6)][FAP], but not in the other ionic liquids studied, guanine reduction involves a one-electron, diffusion-controlled process at very negative potential to produce an unstable radical anion, which is thought to undergo a dimerization reaction, probably after proton abstraction from the cation of the ionic liquid. The rate of this subsequent reaction depends on the nature of the ionic liquid, and it is faster in the ionic liquid [P(14,6,6,6)][FAP], in which the formation of the resulting dimer can be voltammetrically monitored at less negative potentials than required for the reduction of the parent molecule. Adenine showed similar behaviour to guanine but the pyrimidines thymine and cytosine did not; thymine was not reduced at potentials less negative than required for solvent (RTIL) decomposition while only a poorly defined wave was seen for cytosine. The possibility for proton abstraction from the cation in [N(6,2,2,2)][NTf(2)] and [P(14,6,6,6)][FAP] is noted and this is thought to aid the electrochemical dimerization process. The resulting rapid reaction is thought to shift the reduction potentials for guanine and adenine to lower values than observed in RTILs where the scope for proton abstraction is not present. Such shifts are characteristic of so-called EC processes where reversible electron transfer is followed by a chemical reaction. PMID:20103112

Zanoni, Maria Valnice Boldrin; Rogers, Emma I; Hardacre, Christopher; Compton, Richard G



The electrodeposition of Mn and Zn–Mn alloys from the room-temperature tri-1-butylmethylammonium bis((trifluoromethane)sulfonyl)imide ionic liquid  

Microsoft Academic Search

Zinc, manganese and zinc–manganese alloys were electrodeposited from the hydrophobic room-temperature ionic liquid, tri-1-butylmethylammonium bis((trifluoromethane)sulfonyl)imide. Zn(II) and Mn(II) species needed to produce these alloys were introduced into the ionic liquid by the anodic dissolution of the respective metallic electrodes. The diffusion coefficients of the dissolved Zn(II) and Mn(II) species are not constant, but decrease with the increasing concentrations of these

Po-Yu Chen; Charles L. Hussey



The glass transition and the distribution of voids in room-temperature ionic liquids: a molecular dynamics study.  


The glass transition in prototypical room temperature ionic liquids has been investigated by molecular dynamics simulations based on an Amber-like empirical force field. Samples of [C(4)mim][PF(6)], [C(4)mim][Tf(2)N], and [C(3)mim][Tf(2)N] have been quenched from the liquid phase at T = 500 to a glassy state at T ? 0 K in discontinuous steps of 20 K every 1.2 ns. The glass temperature estimated by simulation (T(g) = 209 K for [C(4)mim][PF(6)], T(g) = 204 K for [C(4)mim][Tf(2)N], and T(g) = 196 K for [C(3)mim][Tf(2)N]) agrees semi-quantitatively with the experimental values (T(g) = 193÷196 K for [C(4)mim][PF(6)], T(g) = 186÷189 K for [C(4)mim][Tf(2)N], and T(g) = 183 K for [C(3)mim][Tf(2)N]). A model electron density is introduced to identify voids in the system. The temperature dependence of the size distribution of voids provided by simulation reproduce well the experimental results of positron annihilation lifetime spectroscopy reported in G. Dlubek, Y. Yu, R. Krause-Rehberg, W. Beichel, S. Bulut, N. Pogodina, I. Krossing, and Ch. Friedrich, J. Chem. Phys. 133, 124502 (2010), with only one free parameter needed to fit the experimental data. PMID:22667574

Forero-Martinez, N C; Cortes-Huerto, R; Ballone, P



Volumetric Study of Binary Solvent Mixtures Constituted by Amphiphilic Ionic Liquids at Room Temperature (1Alkyl3-Methylimidazolium Bromide) and Water  

Microsoft Academic Search

At room temperature, the 1-decyl-3-methylimidazolium bromide (DMImBr) is a long alkyl chain imidazolium ionic liquid miscible with water and forming a gel zone between 5 and 40% w\\/w H2O. We measured the density of the liquid mixtures of water and DMImBr. We determined the apparent molar volume of the molten salt for dilute solutions. For the concentrated solutions the partial

Laurent Gaillon; Juliette Sirieix-Plenet; Pierre Letellier



Liquid-liquid extraction of Pu(IV), U(VI) and Am(III) using malonamide in room temperature ionic liquid as diluent.  


The extraction behavior of U(VI), Pu(IV) and Am(III) from nitric acid medium by a solution of N,N-dimethyl-N,N-dioctyl-2-(2-hexyloxyethyl)malonamide (DMDOHEMA) in the room temperature ionic liquid, 1-butyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide (C(4)mimNTf(2)), was studied. The distribution ratio of these actinides in DMDOHEMA/C(4)mimNTf(2) was measured as a function of various parameters such as the concentration of nitric acid, DMDOHEMA, NTf(2)(-), alkyl chain length of ionic liquid. The extraction of actinides in the absence of DMDOHEMA was insignificant and the distribution ratio achieved in conjunction with C(4)mimNTf(2), was remarkable. The separation factor of U(VI) and Pu(IV) achieved with the use of DMDOHEMA, ionic liquid was compared with Am(III) and other fission products. The stoichiometry of the metal-solvate was determined to be 1:2 for U(VI) and Pu(IV) and 1:3 for Am(III). PMID:22541638

Rout, Alok; Venkatesan, K A; Srinivasan, T G; Vasudeva Rao, P R



Electrochemical deposition of ZnO in a room temperature ionic liquid: 1Butyl1-methylpyrrolidinium bis(trifluoromethane sulfonyl)imide  

Microsoft Academic Search

An innovative electrochemical route is proposed to deposit nanocrystalline ZnO films. The approach is based on the electrochemical reduction of O2 in a solution of zinc bis(trifluoromethanesulfonyl)imide salt in 1-butyl-1-methylpyrrolidinium bis(trifluoromethanesulfonyl)imide room temperature ionic liquid. The mechanisms involved in the deposition process are analyzed by cyclic voltammetry, pointing out that the ZnO formation occurs from the chemical reaction between the

E. Azaceta; R. Tena-Zaera; R. Marcilla; S. Fantini; J. Echeberria; J. A. Pomposo; H. Grande; D. Mecerreyes



Direct electrochemistry and electrocatalysis of myoglobin based on silica-coated gold nanorods\\/room temperature ionic liquid\\/silica sol–gel composite film  

Microsoft Academic Search

A novel biosensor based on the silica-coated gold nanorods (GNRs@SiO2) and hydrophilic room temperature ionic liquid (RTIL) 1-butyl-3-methylimidazolium tetrafluroborate ([bmim][BF4]) was fabricated for the determination of hydrogen peroxide (H2O2) and nitrite. GNRs@SiO2 can not only act as a binder to hinder [bmim][BF4] (RTIL) leaking from the electrode surface, but also provide a favorable microenvironment for direct electrochemistry of myoglobin (Mb).

Wen-Lei Zhu; Yang Zhou; Jian-Rong Zhang



Investigation of the Effect of Functional Group Substitutions on the Gas-Phase Electron Affinities and Ionization Energies of Room-Temperature Ionic Liquids Ions using Density Functional Theory  

E-print Network

The cathodic and anodic stabilities of room-temperature ionic liquids (ILs) are important factors in their applications in electrochemical devices. In this work, we investigated the electron affinities of cations and ...

Ong, Shyue Ping


Autocatalytic sonolysis of iron pentacarbonyl in room temperature ionic liquid [BuMeIm][Tf2N].  


The autocatalytic sonochemical reaction of Fe(CO)(5) decomposition in [BuMeIm][Tf(2)N] provides iron nanoparticles in higher yields than in tetralin. Such a difference is explained by the higher decomposition of the intermediate Fe(3)(CO)(12) according to the two-sites model of the sonochemical reactions and the specific properties of the ionic liquid. PMID:21152579

Lartigue, Lenaïc; Pflieger, Rachel; Nikitenko, Sergey I; Guari, Yannick; Stievano, Lorenzo; Sougrati, Moulay T; Larionova, Joulia



Usefulness of reversed-phase HPLC enriched with room temperature imidazolium based ionic liquids for lipophilicity determination of the newly synthesized analgesic active urea derivatives.  


Lipophilicity of several novel analgesic active 1-(1-arylimidazolidyn-2-ylidyn)-3-arylalkyl urea derivatives has been estimated by the use of chromatographic method. The investigated compounds were analyzed by reversed-phase high performance liquid chromatography (RP-HPLC) using mixtures of methanol or acetonitrile and water with addition of imidazolium based room temperature ionic liquids varying in an anion chaotropicity as the mobile phases. The relationships between log k values vs. concentration of organic solvent was used for determination of the log k(w) values by extrapolation technique. The partition coefficients (log P) values were calculated by means of the Pallas and Spartan 10.0 softwares and further correlated with log k(w) measured experimentally in classical organic-aqueous eluent system and systems modified with ionic liquids addition. It was found that log k(w) values measured in eluent system modified with butyl-methyl imidazoilum chloride correlate the best with the logarithm of partition coefficient calculated by Pallas software (log P(calc.)). Furthermore, it was found that the examined compounds form H-bonding with imidazoilum cation of modifiers improving the chromatographic peak parameters (the symmetry factor, the theoretical plates number) especially when ionic liquid's anion was more chaotropic. Amphiphilic ionic liquid possessing longer alkyl chain substituent (OMIM BF(4)) can be considered as a new cationic surfactant. Micellar conditions improved separation selectivity of chloro- and methoxy substituted derivatives. PMID:22445825

Flieger, Jolanta; Czajkowska-?elazko, Anna; Rz?dkowska, Marzena; Szaco?, El?bieta; Matosiuk, Dariusz



AlCl 3-catalysed dimerization of 1,3-cyclopentadiene in the chloroaluminate room temperature ionic liquid  

Microsoft Academic Search

The dimerization of 1,3-cyclopentadiene has been studied in the chloroaluminate ionic liquids. The rate of dimerization of cyclopentadiene is higher in the 1-ethyl-3-methyl-1H-imidazolium chloride (EMIC)-containing chloroaluminate than in the N-1-butylpyridinium chloride (BPC)-containing chloroaluminate. Acceleration of the dimerization process is noted take place with increasing AlCl3 contents in both BPC and EMIC and is attributed to the Lewis acid catalysis. The

Anil Kumar; Sanjay S Pawar



Ionic liquids as electrolytes  

Microsoft Academic Search

Salts having a low melting point are liquid at room temperature, or even below, and form a new class of liquids usually called room temperature ionic liquids (RTIL). Information about RTILs can be found in the literature with such key words as: room temperature molten salt, low-temperature molten salt, ambient-temperature molten salt, liquid organic salt or simply ionic liquid. Their

Maciej Gali?ski; Andrzej Lewandowski; Izabela St?pniak



Effect of room temperature surface active ionic liquids on aggregated nanostructures of ?-Cyclodextrins: A picosecond fluorescence spectroscopic study  

NASA Astrophysics Data System (ADS)

In this Letter we report on controllable transition of aggregated ?-Cyclodextrins (?-CDs) nanostructures by tuning the concentration of a long chain ionic liquid, 1-dodecyl-3-methyl imidazolium chloride (C12mimCl) added to the aqueous solution of ?-CDs. The gradual increase in concentration of C12mimCl first results in the breaking of ?-CDs aggregates by the formation of inclusion complexes with C12mimCl and then self-organizes into a new supramolecular aggregate. This spontaneous transition from one nanostructure to another has been established by spectroscopic and microscopic studies. It is worth to mention that addition of 1-octyl-3-methyl imidazolium chloride (C8mimCl) does not lead to any such transition.

Kuchlyan, Jagannath; Banerjee, Chiranjib; Ghosh, Surajit; Kundu, Niloy; Banik, Debasis; Sarkar, Nilmoni



Bulk shear-mode contribution to thermally generated capillary waves on a room-temperature ionic-liquid surface  

NASA Astrophysics Data System (ADS)

In the present work, we show that the autocorrelation function of the capillary-wave displacement is expressed by the sum of the ordinary oscillator and the bulk shear-mode terms. The former is expressed by a simple damped oscillator form or a sum of exponentially damping functions depending on the extent of damping. The latter is also written by superposition of exponentially damping modes, and an analytically exact formulation is obtained. We performed surface dynamic light-scattering experiment for the surface of an ionic liquid, 1-butyl- 3-methylimidazolium bis[(trifluoromethyl)sulfonyl]imide, and compared the experimental autocorrelation function with the theoretical one. We observed for the first time the bulk shear-mode contribution, and confirmed that the experimental data is well explained by the theoretical autocorrelation function.

Ohmasa, Y.; Hoshino, T.; Osada, R.; Yao, M.



Biosensor based on the biocatalysis of microperoxidase-11 in nanocomposite material of multiwalled carbon nanotubes/room temperature ionic liquid for amperometric determination of hydrogen peroxide.  


A novel nanocomposite material of multiwalled carbon nanotubes (MWCNTs) and room temperature ionic liquid (RTIL) N-butylpyridinium hexafluorophosphate (BPPF6) was explored and used to construct a novel microperoxidase-11 (MP-11) biosensor for the determination of hydrogen peroxide (H2O2). Cyclic voltammetry (CV) and differential pulse voltammetry (DPV) were used to characterize the performance of the biosensor. Under the optimized experimental conditions, H2O2 could be detected in a linear calibration range of 0.5 to 7.0 x 10(-7)mol L(-1) with a correlation coefficient of 0.9949 (n=9) and a detection limit of 3.8 x 10(-9) mol L(-1) at 3 sigma. The modified electrodes displayed excellent electrochemical response, high sensitivity, long-term stability, and good bioactivity and selectivity. PMID:19166808

Wan, Jun; Bi, Jianli; Du, Ping; Zhang, Shusheng



Room temperature ionic liquids: new GC stationary phases with a novel selectivity for flavor and fragrance analyses.  


Ionic liquids (ILs) are of great interest as moderately polar to polar stationary phases for GC, because their selectivity differs markedly from that of conventionally used phases. In the flavor, fragrance and essential oil fields, analysts often deal with complex mixtures of compounds having similar structural and physical characteristics (e.g., mono- and sesquiterpenoids), therefore requiring an interactive combination between chromatographic and mass spectral data for correct identification. New GC stationary phases with different selectivity must therefore be continually tested. Performance and evolution over time of commercially available IL columns versus those commonly used in these fields are here evaluated, mainly in view of their routine use. Chromatographic and separative properties (efficiency, separation capability, inertness and/or activity) of commercially available IL columns were compared to those of columns coated with 5% phenyl-95% methylpolysiloxane, 14% cyanopropyl-86% polysiloxane, and polyethylene glycol, on different complexity samples, including standard mixtures of volatile suspected allergens and pesticides, and cornmint and vetiver essential oils. The results show that IL columns can successfully be used for a wide range of applications characteristic of these fields, mainly because of their unusual selectivity, in particular when separations based on functional groups are required. Moreover, the latest generation of IL columns (IL61 and IL60) presents chromatographic performance comparable to or only slightly lower than that of the conventional columns routinely used in these fields. PMID:23122273

Cagliero, Cecilia; Bicchi, Carlo; Cordero, Chiara; Liberto, Erica; Sgorbini, Barbara; Rubiolo, Patrizia



Cyclic voltammetry of Th(IV) in the room-temperature ionic liquid [Me3NnBu][N(SO2CF3)2].  


A Th(IV) compound, [Th(TFSI)4(HTFSI)].2H2O [where TFSI = N(SO2CF3)2], has been synthesized and characterized using elemental analysis, thermogravimetric analysis, and vibrational spectroscopy. The analysis suggests that the TFSI anion coordinates to the metal center via the sulfonyl oxygens as well as provides evidence for the coordination of HTFSI. The voltammetric behavior of this compound has been studied in the room-temperature ionic liquid [Me3NnBu][TFSI], and results show that Th(IV) is reduced to Th(0) in this ionic liquid in a single reduction step. Analysis of cyclic voltammograms shows that an insoluble product is being formed at the electrode surface, which is attributed to the formation of ThO2 by reaction with water. The E0 value for the reduction of Th(IV) to Th(0) has been determined to be -2.20 V (vs Fc+/Fc; -1.80 V vs SHE). A comparison of this E0 value with those obtained for Th(IV) reduction in a LiCl-KCl eutectic (400 degrees C), water, and nonaqueous solvents shows that the reduction in [Me3NnBu][TFSI] is easier to accomplish than that in these other solvents. PMID:16471980

Bhatt, Anand I; Duffy, Noel W; Collison, David; May, Iain; Lewin, Robert G



A kinetic study of the reaction between N,N-dimethyl-p-toluidine and its electrogenerated radical cation in a room temperature ionic liquid.  


The reaction between N,N-dimethyl-p-toluidine (DMT) and the radical cation generated through its one-electron oxidation has been studied electrochemically in the room temperature ionic liquid N-methyl-N-butylpyrrolidinium bis(trifluoromethylsulfonyl)imide, [Py14][NTf2]. Kinetic information obtained as linear sweep and cyclic voltammetry collected at 5 microm, 10 microm and 0.3 mm diameter platinum disk electrodes over a range of initial substrate concentrations and scan rates spanning five orders of magnitude was complemented by chronoamperometric measurements designed to probe the rate of diffusion. At the fastest scan rates the homogeneous reactions following the initial electron transfer were effectively out-run, facilitating an assessment of the electrode kinetics using DIGISIM and a validated Nicholson's method. Through digital simulation the voltammetry was then shown to be consistent with a mechanism established for the same reaction in acetonitrile, involving dimerisation of the DMT radicals following an initial and rate-determining proton transfer step. After careful consideration of all parameters, a bimolecular rate constant of (3.4 +/- 1.1) x 10(2) dm3 mol(-1) s(-1) was deduced by fitting the data. This was compared to the equivalent value for acetonitrile and, in light of this, the implications on the viability of ionic liquids for use as alternative mainstream solvents briefly assessed. PMID:16463338

Evans, Russell G; Compton, Richard G



Alkali cation extraction by calix[4]crown-6 to room-temperature ionic liquids. The effect of solvent anion and humidity investigated by molecular dynamics simulations.  


We report a molecular dynamics study on the solvation of M+ (Na+ to Cs+) alkali cations and of their LM+ complexes with a calix[4]arene host (L = 1,3-dimethoxy-calix[4]arene-crown-6 in the 1,3-alternate conformation) in the [BMI][PF6] and [BMI][Tf2N] room-temperature ionic liquids "ILs" based on the BMI+ (1-butyl-3-methylimidazolium) cation. The comparison of the two liquids and the dry versus humid form of the former one (with a 1:1 ratio of H2O and BMI+PF6- species) reveals the importance of humidity: in [BMI][PF6]-dry as in the [BMI][Tf2N] liquid, the first solvation shell of the "naked" M+ ions is composed of solvent anions only (four PF6- anions, and from four to five Tf2N- anions, respectively, quasi-neutralized by a surrounding cage of BMI+ cations), while in the [BMI][PF6]-humid IL, it comprises from one to three solvent anions and about four H2O molecules. In the LM+ complexes, the cation is shielded from solvent, but still somewhat interacts with a solvent anion in the dry ILs and with water in the humid IL. We also report tests on M+ interactions with solvent anions PF6- and Tf2N- in the gas phase, showing that the AMBER results are in satisfactory agreement with QM results obtained at different levels of theory. The question of ion recognition by L is then examined by free energy perturbation studies in the three liquids, predicting a high Cs+/Na+ selectivity upon liquid extraction from an aqueous phase, in agreement with experimental results on a parent calixarene host. A similar Cs+/Na+ selectivity is predicted upon complexation in a homogeneous IL phase, mainly due to the desolvation energy of the free cations. Thus, despite their polar character, ionic liquids qualitatively behave as classical weakly polar organic liquids (e.g., choroform) as far as liquid-liquid extraction is concerned but more like polar liquids (water, alcohols) as far as complexation in a single phase is concerned. PMID:16420015

Sieffert, N; Wipff, G



Structure and stability of phospholipid bilayers hydrated by a room-temperature ionic liquid/water solution: a neutron reflectometry study.  


Neutron reflectometry (NR) measurements were carried out to probe the structure and stability of two model biomembranes consisting of 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine (POPC) and 1,2-dimyristoyl-sn-glycero-3-phosphatidylcholine (DMPC) phospholipid bilayers hydrated by water solutions of two prototypical room-temperature ionic liquids (RTILs), namely, 1-butyl-3-methyl-imidazolium chloride ([bmim][Cl]) and choline chloride ([Chol][Cl]) at concentrations of 0.1 M and 0.5 M, respectively. The raw data were analyzed by fitting a distribution of scattering length densities arising from the different chemical species in the system. The results of this analysis show that (a) for all systems and concentrations that we considered, the thickness of the bilayers shrinks by ?1 Å upon dissolving the ionic liquid into water and that (b) the RTIL ions enter the bilayer, finding their way to a preferred location in the lipid range that is nearly independent of the lipid and of the [bimim](+) or [Chol](+) choice. The volume fraction of RTIL sorbed in/on the bilayer, however, does depend on the lipid, but, again, is the same for [bmim][Cl] and for [Chol][Cl]. Thus, the RTIL occupies ?5% of the bilayer volume in POPC, rising to ?10% in DMPC. Repeating the measurements and data analysis after rinsing in pure water shows that the changes in the bilayer due to the RTIL sorption are irreversible and that a measurable amount of IL remains in the lipid fraction, that is, ?2.5% of the bilayer volume in POPC and ?8% in DMPC. PMID:25251987

Benedetto, Antonio; Heinrich, Frank; Gonzalez, Miguel A; Fragneto, Giovanna; Watkins, Erik; Ballone, Pietro



Determination of Thermal Diffusivities, Thermal Conductivities, and Sound Speeds of Room-Temperature Ionic Liquids by the Transient Grating Technique  

E-print Network

, does not significantly influence the sound speed or the thermal diffusivity of the RTILs. Introduction-temperature1-8 lubricants. It is probable that industrial applications of RTILs in chemistry, engineering-11 and can be used to determine thermophysical properties of solids, liquids, and gases. The method is based

Reid, Scott A.


A comparison of ether- and alkyl-derivatized imidazolium-based room-temperature ionic liquids: a molecular dynamics simulation study.  


Molecular dynamics simulations of ether-derivatized imidazolium-based room-temperature ionic liquids (EDI-RTILs), [C(5)O(2)mim][TFSI] and [C(5)O(2)mim][BF(4)], have been performed and compared with simulations of alkyl-derivatized analogues (ADI-RTILs). Simulations yield RTIL densities, self-diffusion coefficients and viscosity in excellent agreement with experimental data. Simulations reveal that structure in the EDI-RTILs, quantified by the extent of nanoscale segregation of tails as well as cation-ion and cation-cation correlations, is reduced compared to that observed in the ADI-RTILs. Significant correlation between ether tail oxygen atoms and imidazolium ring hydrogen atoms was observed in the EDI-RTILs. This correlation is primarily intramolecular in origin but has a significant intermolecular component. Competition of ether oxygen atoms with oxygen atoms of TFSI(-) or fluorine atoms of BF(4)(-) for coordination of the ring hydrogen atoms was found to reduce the extent of cation-anion correlation in the EDI-RTILs compared to the ADI-RTILs. The reduction in intermolecular correlation, particularly tail-tail segregation, as well as weakening of cation-anion specific interactions due to the ether tail, may account for the faster dynamics observed in the EDI-RTILs compared to ADI-RTILs. PMID:18936854

Smith, Grant D; Borodin, Oleg; Li, Liyong; Kim, Hojin; Liu, Qin; Bara, Jason E; Gin, Douglas L; Nobel, Richard



Diglycolamide-functionalized calix[4]arenes showing unusual complexation of actinide ions in room temperature ionic liquids: role of ligand structure, radiolytic stability, emission spectroscopy, and thermodynamic studies.  


Diglycolamide-functionalized calix[4]arenes (C4DGAs) with varying structural modifications were evaluated for actinide complexation from their extraction behavior toward actinide ions such as UO2(2+), Pu(4+), PuO2(2+), and Am(3+) in the room temperature ionic liquid (RTIL) 1-n-octyl-3-methylimidazolium bis(trifluoromethane)sulfonamide (C8mimNTf2). The formation constants were calculated for Am(3+) which showed a significant role of ligand structure, nature of substituents, and spacer length. Although the alkyl substituents on the amidic nitrogen increase the extraction efficiency of americium at lower acidity because of the inductive effect of the alkyl groups, at higher acidity the steric crowding around the ligating site determines the extraction efficiency. All C4DGAs formed 1:1 complexes with Am(3+) while for the analogous Eu(3+) complexes no inner sphere water molecules were detected and the asymmetry of the metal ligand complex differed from one another as proved by time-resolved laser induced fluorescence spectroscopy (TRLIFS). Thermodynamic studies indicated that the extraction process, predominant by the Am(3+)-C4DGA complexation reaction, is exothermic. The unique role of the medium on Am(3+) complexation with the C4DGA molecules with varying spacer length, L-IV and L-V, was noticed for the first time with a reversal in the trend observed in the RTIL compared to that seen in a nonpolar molecular diluent like n-dodecane. Various factors leading to a more preorganized structure were responsible for favorable metal ion complexation. The solvent systems show promise to be employed for nuclear waste remediation, and sustainability options were evaluated from radiolytic stability as well as stripping studies. PMID:23394577

Mohapatra, Prasanta K; Sengupta, Arijit; Iqbal, Mudassir; Huskens, Jurriaan; Verboom, Willem



Synthesis and development of ordered, phase-separated, room-temperature ionic liquid-based AB and ABC block copolymers for gas separation applications  

NASA Astrophysics Data System (ADS)

CO2 capture process development is an economically and environmentally important challenge, as concerns over greenhouse gas emissions continue to receive worldwide attention. Many applications require the separation of CO 2 from other light gases such as N2, CH4, and H2 and a number of technologies have been developed to perform such separations. While current membrane technology offers an economical, easy to operate and scale-up solution, polymeric membranes cannot withstand high temperatures and aggressive chemical environments, and they often exhibit an unfavorable tradeoff between permeability and selectivity. Room-temperature ionic-liquids (RTILs) are very attractive as next-generation CO2-selective separation media and their development into polymerized membranes combat these challenges. Furthermore, polymers that can self-assemble into nanostructured, phase-separated morphologies (e.g., block copolymers, BCPs) have a direct effect on gas transport as materials morphology can influence molecular diffusion and membrane transport performance. In this thesis, nanophase-separated, RTIL-based AB and ABC di- and tri-BCPs were prepared via the sequential, living ring-opening metathesis polymerization (ROMP) of an IL-based monomer and one or more mutually immiscible co-monomers. This novel type of ion-containing BCP system forms various ordered nanostructures in the melt state via primary and secondary structure control. Monomer design and control of block composition, sequence, and overall polymer lengths were found to directly affect the ordered polymer assembly. Supported, composite membranes of these new BCPs were successfully fabricated, and the effect of BCP composition and nanostructure on CO2/light gas transport properties was studied. These nanostructured IL-based BCPs represent innovative polymer architectures and show great potential CO2/light gas membrane separation applications.

Wiesenauer, Erin F.


Room-Temperature Liquid Crystal Blue Phases  

NASA Astrophysics Data System (ADS)

The ``blue phases'' of a highly chiral liquid crystal are defect-studded structures of double-twist cylinders that are laced together. The three phases, BPI*, BPII* and BPIII* differ only in the packing of the double-twist cylinders. Until recently, blue phases were of limited practical use because they appeared for only a very narrow temperature range. Mixtures that show BPI* and BPII* phases for wide temperature ranges at or around room temperature are now available [1]. Relatively wide temperature BPIII (the blue fog) phase so far was available only at very high temperatures [2]. Here we present mixtures with room-temperature wide range BPIII* phase and compare the ability of chiral dopants to form the different blue phases in a base nematic mixture. PDLC films cast with blue-phase material are also examined.[3pt] [1] H. Coles and M. Pivnenko, Nature 2005 436-18 997-1000 [0pt] [2] C. V. Yelamaggad, I. S. Shashikala, G. Liao, D.S. Shankar Rao, S. K. Prasad , Q. Li A. Jakli, Chem. Mater Comm, 2006, 18, 6100-6102

Taushanoff, Stefanie; van Le, Khoa; Twieg, Robert; Jakli, Antal



Solvation of fluoro and mixed fluoro/chloro complexes of EuIII the [BMI][PF6] room temperature ionic liquid. A theoretical studyw  

E-print Network

components are macroscopically non-miscible with water, and can thus be used for liquid­liquid extraction­liquid extraction purposes. The solvents were first considered in the ``ideal'' neat state, but it was shown later.g. to investigate the effect of adding fluoride salts to an europium solution in the ionic liquid. Furthermore, F

Paris-Sud XI, Université de


Phase Behavior of N2O and CO2 in Room-Temperature Ionic Liquids [bmim][Tf2N], [bmim][BF4], [bmim][N(CN)2], [bmim][Ac], [eam][NO3], and [bmim][SCN  

NASA Astrophysics Data System (ADS)

The gas solubility of nitrous oxide (N2O) in room-temperature ionic liquids, 1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide, 1-butyl-3-methylimidazolium tetrafluoroborate, 1-butyl-3-methylimidazolium dicyanamide, 1-butyl-3-methylimidazolium acetate, 1-butyl-3-methylimidazolium thiocyanate, and ethylammonium nitrate has been measured at isothermal conditions from about (283 to 348)K using a gravimetric microbalance. The observed pressure-temperature composition ( PTx) data have been analyzed by use of a generic Redlich-Kwong equation-of-state (EOS) model, which has been successfully applied in our previous works. The interaction parameters have been determined using our measured vapor-liquid equilibrium data. Vapor-liquid-liquid equilibrium measurements have been made and validate EOS model predictions which suggest that these systems demonstrate Type III and Type V phase behavior, according to the classification of van Konynenburg and Scott. The global phase behavior of N2O has also been compared with both the measured data from this study and literature data for carbon dioxide (CO2) in each ionic liquid and Henry's law constants are compared at room temperature (298.15 K).

Shiflett, Mark B.; Niehaus, Anne Marie S.; Elliott, Beth A.; Yokozeki, A.



Supported Phospholipid Bilayer Interaction with Components Found in Typical Room-Temperature Ionic Liquids – a QCM-D and AFM Study  

Microsoft Academic Search

Quartz crystal microbalance with dissipation (QCM-D) monitoring and atomic force microscopy (AFM) were combined to evaluate the defects created by an ionic liquid anion and a cation in a supported phospholipid bilayer composed of zwitterionic lipids on a silica surface. The cation 1-octyl-3-methyl imidazolium (OMIM + ) was shown to remove lipids from the bilayer, increase the roughness to approximately

Kervin O. Evans



Extraction and separation of thorium(IV) from lanthanides(III) with room-temperature ionic liquids containing primary amine N{sub 1923}  

SciTech Connect

The extraction behavior of Th(IV) by primary amine N{sub 1923} in imidazolium-based ionic liquid namely 1-octyl-3-methylimidazolium hexafluorophosphate (N{sub 1923}/IL) was studied in this paper. Results showed that N{sub 1923}/IL had poorer extraction ability for Th(IV) than N{sub 1923} in n-heptane (N{sub 1923}/HEP). The separation coefficients between Th(IV) and lanthanides(III) ({beta}{sub Th/Ln}) were obtained and compared with those in the N{sub 1923}/HEP system. On this basis, we made a preliminary assessment for the possibility of using ionic liquids as solvents for the separation of Th(IV) from lanthanides(III) sulfate in a clean process. (authors)

Zuo, Y. [Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun 130022 (China); Graduate School of Chinese Academy of Sciences, Beijing (China); Chen, J.; Bai, Y.; Li, D.Q. [Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun 130022 (China)



Green synthesis of ZnO nanoparticles in a room-temperature ionic liquid 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide  

Microsoft Academic Search

Nanoparticles of ZnO with the wurtzite structure have been successfully synthesized via a microwave through the decomposition of zinc acetate dihydrate in an ionic liquid, 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide, as a solvent. Fundamental characterizations including X-ray diffraction (XRD), scanning electron microscopy (SEM), and transmission electron microscopy (TEM) were conducted for the ZnO nanostructures.To explore the growth mechanism, the samples have been prepared

Elaheh K. Goharshadi; Yulong Ding; Paul Nancarrow



Solvation structures of some transition metal(II) ions in a room-temperature ionic liquid, 1-ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)amide.  


Solvation structures of manganese(II), cobalt(II), nickel(II) and zinc(II) ions in 1-ethyl-3-methylimidazolium bis(trifluoro-methanesulfonyl) amide (EMI(+)TFSA(-)) have been studied by UV-Vis, FT-IR and FT-Raman spectra. The ionic liquid involves TFSA(-) conformers with C(1) (cis) and C(2) (trans) symmetries, and both conformers coexist in equilibrium in the liquid state. The results showed that these metal(II) ions are all six-coordinated with three TFSA(-) ions, i.e., TFSA(-) ligates as a bidentate O-donor in the ionic liquid. Although the metal ion strongly prefers the C(1) conformer in crystals, the metal ion coordinates both the C(1) and C(2) conformers in the liquid state, and the conformational equilibrium in the bulk only slightly shifts to the C(1) conformer in the coordination sphere. We concluded that the conformational equilibrium in the coordination sphere is strongly temperature-sensitive. PMID:18845905

Fujii, Kenta; Nonaka, Takahiro; Akimoto, Yu; Umebayashi, Yasuhiro; Ishiguro, Shin-ichi



Toward understanding solute-solvent interaction in room-temperature mono- and dicationic ionic liquids: a combined fluorescence spectroscopy and mass spectrometry analysis.  


Rotational relaxation dynamics of nonpolar perylene, dipolar coumarin 153, and a negatively charged probe, sodium 8-methoxypyrene-1,3,6-sulfonate (MPTS), have been investigated in a dicationic ionic liquid, 1,6-bis-(3-methylimidazolium-1-yl)hexane bis-(trifluoromethylsulfonyl)amide ([C6(MIm)2][NTf2]2), and a structurally similar monocationic ionic liquid, 1-hexyl-3-methylimidazolium bis(trifluoromethylsulfonyl)amide ([C6MIm][NTf2]), to have a comprehensive and a quantitative understanding on the solute-solvent interaction in these media. Analysis of the rotational relaxation dynamics data by Stokes-Einstein-Debye (SED) hydrodynamic theory reveals that perylene rotation is found to be the fastest compared to the other two probes and shows slip to sub-slip behavior, coumarin 153 rotation lies between the stick and slip boundary, and MPTS shows a superstick behavior in [C6MIm][NTf2]. Interestingly, MPTS exhibits a normal SED hydrodynamics in dicationic [C6(MIm)2][NTf2]2, in spite of the fact that dicationic ionic liquid contains two cationic sites bearing acidic hydrogen (C2-H) which may be available to form stronger interaction with the negatively charged MPTS. The difference in the rotational diffusion behavior of these three probes is a reflection of their location in different distinct environments of these ILs. Superstick behavior of MPTS in monocationic IL has been attributed to its specific hydrogen bonding interaction with the corresponding imidazolium cation. The relatively faster rotational behavior of MPTS in dicationic IL has been explained by resorting to mass spectrometry. Mass spectral analysis demonstrates that positively charged (imidazolium) sites in dicationic IL are strongly associated with negatively charged bis-(trifluoromethylsulfonyl)amide anion (NTf2(-)), which in turn makes it difficult for imidazolim cation to have stronger hydrogen bonding interaction with bulkier negatively charged molecule MPTS. PMID:24476198

Sahu, Prabhat Kumar; Das, Sudhir Kumar; Sarkar, Moloy



The electrochemical reduction of 1-bromo-4-nitrobenzene at zinc electrodes in a room-temperature ionic liquid: a facile route for the formation of arylzinc compounds.  


The electrochemical reduction of 1-bromo-4-nitrobenzene (p-BrC6H4NO2) at zinc microelectrodes in the [C4mPyrr][NTf2] ionic liquid was investigated via cyclic voltammetry. The reduction was found to occur via an EC type mechanism, where p-BrC6H4NO2 is first reduced by one electron, quasi-reversibly, to yield the corresponding radical anion. The radical anions then react with the Zn electrode to form arylzinc products. Introduction of carbon dioxide into the system led to reaction with the arylzinc species, fingerprinting the formation of the latter. This method thus demonstrates a proof-of-concept of the formation of functionalised arylzinc species. PMID:24473222

Ernst, Sven; Norman, Sarah E; Hardacre, Christopher; Compton, Richard G



Effect of Temperature on the Physico-Chemical Properties of a Room Temperature Ionic Liquid (1-Methyl-3-pentylimidazolium Hexafluorophosphate) with Polyethylene Glycol Oligomer  

PubMed Central

A systematic study of the effect of composition on the thermo-physical properties of the binary mixtures of 1-methyl-3-pentyl imidazolium hexafluorophosphate [MPI][PF6] with poly(ethylene glycol) (PEG) [Mw = 400] is presented. The excess molar volume, refractive index deviation, viscosity deviation, and surface tension deviation values were calculated from these experimental density, ?, refractive index, n, viscosity, ?, and surface tension, ?, over the whole concentration range, respectively. The excess molar volumes are negative and continue to become increasingly negative with increasing temperature; whereas the viscosity and surface tension deviation are negative and become less negative with increasing temperature. The surface thermodynamic functions, such as surface entropy, enthalpy, as well as standard molar entropy, Parachor, and molar enthalpy of vaporization for pure ionic liquid, have been derived from the temperature dependence of the surface tension values. PMID:21731460

Wu, Tzi-Yi; Chen, Bor-Kuan; Hao, Lin; Peng, Yu-Chun; Sun, I-Wen



Self polymerising ionic liquid gel.  


A novel self-polymerised ionic liquid (IL) gel was prepared at room temperature (RT), without light or heat or addition of initiator, using a new IL, choline formate (CF), and 2-hydroxyethyl methacrylate (HEMA). PMID:19462080

Winther-Jensen, Orawan; Vijayaraghavan, R; Sun, Jiazeng; Winther-Jensen, Bjorn; MacFarlane, Douglas R



Surface exploration of a room-temperature ionic liquid-chitin composite film decorated with electrochemically deposited PdFeNi trimetallic alloy nanoparticles by pattern recognition: An elegant approach to developing a novel biotin biosensor.  


In this study, a novel biosensing system for the determination of biotin (BTN) based on electrodeposition of palladium-iron-nickel (PdFeNi) trimetallic alloy nanoparticles (NPs) onto a glassy carbon electrode (GCE) modified with a room-temperature ionic liquid (RTIL)-chitin (Ch) composite film (PdFeNi/ChRTIL/GCE) is established. NPs have a wide range of applications in science and technology and their sizes are often measured using transmission electron microscopy (TEM) or X-ray diffraction. Here, we used a pattern recognition method (digital image processing, DIP) for measuring particle size distributions (PSDs) from scanning electron microscopic (SEM) images in the presence of an uneven background. Different depositions were performed by varying the number of cyclic potential scans (N) during electroreduction step. It was observed that the physicochemical properties of the deposits were correlated to the performance of the PdFeNi/ChRTIL/GCE with respect to BTN assay. The best results were obtained for eight electrodeposition cyclic scans, where small-sized particles (19.54±6.27nm) with high density (682particlesµm(-2)) were obtained. Under optimized conditions, a linear range from 2.0 to 44.0×10(-9)molL(-1) and a limit of detection (LOD) of 0.6×10(-9)molL(-1) were obtained. The PdFeNi/ChRTIL nanocomposite showed excellent compatibility, enhanced electron transfer kinetics, large electroactive surface area, and was highly sensitive, selective, and stable toward BTN determination. Finally, the PdFeNi/ChRTIL/GCE was satisfactorily applied to the determination of BTN in infant milk powder, liver, and egg yolk samples. PMID:25281100

Gholivand, Mohammad-Bagher; Jalalvand, Ali R; Goicoechea, Hector C; Paimard, Giti; Skov, Thomas



New electrolytes for aluminum production: Ionic liquids  

NASA Astrophysics Data System (ADS)

In this article, the reduction, refining/recycling, and electroplating of aluminum from room-temperature molten salts are reviewed. In addition, the characteristics of several non-conventional organic solvents, electrolytes, and molten salts are evaluated, and the applicability of these melts for production of aluminum is discussed with special attention to ionic liquids. Also reviewed are electrochemical processes and conditions for electrodeposition of aluminum using ionic liquids at near room temperatures.

Zhang, Mingming; Kamavarum, Venkat; Reddy, Ramana G.



Ionic liquid ion source emitter arrays fabricated on bulk porous substrates for spacecraft propulsion  

E-print Network

Ionic Liquid Ion Sources (ILIS) are a subset of electrospray capable of producing bipolar beams of pure ions from ionic liquids. Ionic liquids are room temperature molten salts, characterized by negligible vapor pressures, ...

Courtney, Daniel George



The room temperature annealing peak in ionomers: Ionic crystallites or water absorption  

SciTech Connect

A quaternized diol, 3-(trimethylammonio)-1,2-propanediol neutralized with either bromine or iodine, was used to produce a polyurethane cationomer with a poly(tetramethylene oxide) soft segment and a 4,4[prime]-diphenylmethane diisocyanate hard segment. If those cationomers were annealed at room temperature for a period of approximately 1 month in a desiccator filled with dry CaSO[sub 4], differential scanning calorimetry (DSC) studies showed an endotherm centered near 70 C which was not present in the unannealed polymer and did not reappear upon subsequent cooling and heating cycles in the DSC. Some authors have suggested that a very similar endotherm found in other ionomers, most notably ethylene-methacrylic acid (E-MAA) copolymer ionomers, was due to an order-disorder transition within the ionic aggregates, i.e. ionic crystallite melting. In order to isolate the origin of this endotherm, the local environment around the anion in compression molded bromine neutralized samples was measured using the extended X-ray absorption fine-structure (EXAFS) technique. By measuring the change in the local environment over the temperature range corresponding to the DSC endotherm, it has been shown that this endotherm corresponds to water leaving the bromine coordination shell, rather than ionic crystallite melting. Other studies which include thoroughly drying the material in a vacuum oven below the transition temperature to remove the water suggest that the endotherm is due to the energetic change associated with water leaving the coordination environment of the anion in combination with water vaporization.

Goddard, R.J.; Grady, B.P.; Cooper, S.L. (Univ. of Wisconsin, Madison, WI (United States). Dept. of Chemical Engineering)



Imidazolium ionic liquids as electrolytes for manganese dioxide free Leclanché batteries  

Microsoft Academic Search

A set of four imidazolium ionic liquids (solid at room temperature) and one imidazolium ionic solid was screened for its potential as electrolytes in manganese dioxide free Leclanché batteries, equipped with a zinc anode and graphite cathode. Electrical impedance spectroscopy allowed to determine the room-temperature ionic solids (RTISs) ionic conductivities, which was the highest for carboxylic acid functionalized RTIS 3

M. P. Stracke; M. V. Migliorini; E. Lissner; H. S. Schrekker; J. Dupont; R. S. Gonçalves



Living cationic polymerisation of styrene in an ionic liquid.  


For the first time, living cationic polymerisation of styrene has been carried out in room temperature ionic liquids under mild reaction conditions and using mild acid catalysts (e.g. organoborate acids) to obtain polymers of narrow polydispersity. PMID:15010788

Vijayaraghavan, R; MacFarlane, D R



Ionic Liquids Database- (ILThermo)  

National Institute of Standards and Technology Data Gateway

SRD 147 Ionic Liquids Database- (ILThermo) (Web, free access)   IUPAC Ionic Liquids Database, ILThermo, is a free web research tool that allows users worldwide to access an up-to-date data collection from the publications on experimental investigations of thermodynamic, and transport properties of ionic liquids as well as binary and ternary mixtures containing ionic liquids.


Electrochemical transistors with ionic liquids for enzymatic sensing  

E-print Network

and anions. According to the current convention, a salt melting below the normal boiling point of water and lactate. Room temperature ionic liquids (RTILs) are organic salts, which are liquid at ambient temperature 1. INTRODUCTION 1.1 Organic Salts / Ionic Liquids Salts are generally regarded to be solid

Lee, Hyowon


Chemistry in heterocyclic ammonium fluorohydrogenate room-temperature ionic liquid  

Microsoft Academic Search

Investigation on alkali fluoride–HF system has been initiated in the 19th century. The technique is currently utilized in fluorine-chemical industry. But, the problem is that this system readily releases hazardous HF. Although organic base, e.g., amine, with HF, which is mainly applied to fluorination treatment for organic compound, reduces the HF release, the solution still requires careful handling because of

Tetsuya Tsuda; Rika Hagiwara



Measurement of the Order Parameter in a Room Temperature Liquid Crystal: An Experiment for the Physical Chemistry Laboratory.  

ERIC Educational Resources Information Center

Presented here is a laboratory experiment for a course in physical chemistry. Students are requested to directly measure the degree of orientational order in a liquid crystal at room temperature. A minimum amount of equipment is necessary. (Author/SA)

DuPre, Donald B.; Chapoy, L. Lawrence



The use of ionic liquid ion sources (ILIS) in FIB applications  

E-print Network

A new monoenergetic, high-brightness ion source can be constructed using an arrangement similar to liquid metal ion sources (LMIS) by substituting the liquid metal with an ionic liquid, or room temperature molten salt. Ion ...

Zorzos, Anthony Nicholas



Alkylation of naphthalene using three different ionic liquids  

Microsoft Academic Search

It is well known that room temperature ionic liquids (Ils) have the potential for serving as efficient reaction media in the Friedel–Crafts reactions of naphthalene. In this work, three ionic liquid systems prepared with AlCl3 were used as reaction media for the alkylation of naphthalene with different reagents. The following cations were used to prepare the chloroaluminate(III) ionic liquids: 1-butyl-3-methylimidazolium

Carlos Gutierrez Blanco; Dolores Casal Banciella; M. Dolores González Azpíroz



Structural requirements for producing solvent-free room temperature liquid fullerenes.  


A new class of solvent-free room temperature liquid fullerenes was synthesized by attaching a single substituent of 1,3,5-tris(alkyloxy)benzene unit to C60 or C70 under the Prato conditions. Although the C60 monoadducts were single components after chromatographic purification, the C70 monoadducts were isomeric mixtures due to the prolate spheroidal ?-chromophore. The alkyl chain length of the substituents significantly affected both melting points and rheological behavior of the fullerene derivatives. When the alkyl chains were short, the intermolecular ?-? interactions of adjacent fullerene cores led to a melting point higher than room temperature. In contrast, in the case of exceedingly long alkyl chains, such as eicosyl (-C20H41) and docosanyl (-C22H45) groups, the van der Waals interactions among neighboring alkyl chains became dominant. Accordingly, only medium alkyl chain lengths could provide solvent-free fluidic fullerenes with low melting points. The rheological measurements of the liquid fullerenes at 25 °C revealed their unique liquid characteristics; molecular-level friction (or viscosity) and nanometer-scale clustering were noticed. It is generally thought that alkyl chains serve as a stabilizer of the fullerene core units. Thus, a longer chain or higher plasticity of the stabilizers would promote the disturbance of the core-core interactions. It was indeed shown that longer alkyl chains resulted in a lower fluid viscosity. It was also found that metastable solid phases were produced by the noticeable van der Waals interaction between the long alkyl chains especially when a symmetric C60 core was adopted. This interesting finding enabled the comparison of electrochemical activities of the C60 unit between the solvent-free liquid and metastable solid form, which revealed a superior electrochemical activity in the liquid state. PMID:23547957

Michinobu, Tsuyoshi; Okoshi, Kensuke; Murakami, Yoshihiko; Shigehara, Kiyotaka; Ariga, Katsuhiko; Nakanishi, Takashi



Tunable emissive lanthanidomesogen derived from a room-temperature liquid-crystalline Schiff-base ligand.  


A novel photoluminescent room-temperature liquid-crystalline salicylaldimine Schiff base with a short alkoxy substituent and a series of lanthanide(III) complexes of the type [Ln(LH)3(NO3)3] (Ln = La, Pr, Sm, Gd, Tb, Dy; LH = (E)-5-(hexyloxy)-2-[{2-(2-hydroxyethylamino)ethylimino]methyl}phenol) have been synthesized and characterized by FTIR, (1)H and (13)C?NMR, UV/Vis, and FAB-MS analyses. The ligand coordinates to the metal ions in its zwitterionic form. The thermal behavior of the compounds was investigated by polarizing optical microscopy (POM) and differential scanning calorimetry (DSC). The ligand exhibits an enantiotropic hexagonal columnar (Col(h)) mesophase at room temperature and the complexes show an enantiotropic lamellar columnar (Col(L)) phase at around 120?°C with high thermal stability. Based on XRD results, different space-filling models have been proposed for the ligand and complexes to account for the columnar mesomorphism. The ligand exhibits intense blue emission both in solution and in the condensed state. The most intense emissions were observed for the samarium and terbium complexes, with the samarium complex glowing with a bright-orange light (ca. 560-644?nm) and the terbium complex emitting green light (ca. 490-622?nm) upon UV irradiation. DFT calculations performed by using the DMol3 program at the BLYP/DNP level of theory revealed a nine-coordinate structure for the lanthanide complexes. PMID:23939837

Pramanik, Harun A R; Das, Gobinda; Bhattacharjee, Chira R; Paul, Pradip C; Mondal, Paritosh; Prasad, S Krishna; Rao, D S Shankar



Hydrophobic ionic liquids incorporating N-alkylisoquinolinium cations and their utilization in liquid-liquid separations.  


The first examples of Room Temperature Ionic Liquids (RTIL) containing fused polycyclic N-alkylisoquinolinium cations ([Cnisoq]+) in combination with the bis(perfluoroethylsulfonyl)imide anion ([BETI]-) have been synthesized, characterized, and utilized in liquid-liquid partitioning from water; these salts have unexpectedly low melting points and give high distribution ratios for aromatic solutes, especially chlorobenzenes, between the RTIL and water. PMID:12240026

Visser, A E; Holbrey, J D; Rogers, R D



Liquid crystalline texture in glycine-modified diacetylene Langmuir monolayers at room temperature  

SciTech Connect

Direct visualization of the self-assembling and liquid crystalline texture formation in glycine-modified diacetylene (Gly-DA) Langmuir monolayers at room temperature is achieved using Brewster angle microscopy (BAM). The striped (smectic) texture appears directly after spreading the monolayer at the air-water interface The spatial period of this texture has been estimated to be in the range 0.015-0.005 mm, which is in agreement with the range predicted theoretically for this phase. When pressure is applied, the width of the strips decreases and, finally, the striped texture disappears. Another texture appears in the pressure range 30-35 mN/m: the well-defined pseudo-focal-conic texture, which points to a disordered hexagonal columnar mesophase. In addition, direct visualization of the Gly-DA polymerization under UV radiation exposure via BAM is achieved. We observe focal-conic texture reminiscent of smectic C phase. 18 refs., 3 figs.

Litvin, A.L. (U.S. Army Natick Research, Development Engineering Center, MA (United States) Geo-Centers, Inc., Natick, MA (United States)); Samuelson, L.A.; Kaplan, D.L. (U.S. Army Natick Research, Development Engineering Center, MA (United States)); Spevak, W.; Charych, D.H. (Lawrence Berkeley Lab., CA (United States))



Use of ionic liquids as coordination ligands for organometallic catalysts  


Aspects of the present invention relate to compositions and methods for the use of ionic liquids with dissolved metal compounds as catalysts for a variety of chemical reactions. Ionic liquids are salts that generally are liquids at room temperature, and are capable of dissolving a many types of compounds that are relatively insoluble in aqueous or organic solvent systems. Specifically, ionic liquids may dissolve metal compounds to produce homogeneous and heterogeneous organometallic catalysts. One industrially-important chemical reaction that may be catalyzed by metal-containing ionic liquid catalysts is the conversion of methane to methanol.

Li, Zaiwei (Moreno Valley, CA); Tang, Yongchun (Walnut, CA); Cheng; Jihong (Arcadia, CA)



New electrolytes for aluminum production: Ionic liquids  

Microsoft Academic Search

In this article, the reduction, refining\\/recycling, and electroplating of aluminum from room-temperature molten salts are\\u000a reviewed. In addition, the characteristics of several non-conventional organic solvents, electrolytes, and molten salts are\\u000a evaluated, and the applicability of these melts for production of aluminum is discussed with special attention to ionic liquids.\\u000a Also reviewed are electrochemical processes and conditions for electrodeposition of aluminum

Mingming Zhang; Venkat Kamavarum; Ramana G. Reddy



An organocatalytic ionic liquid.  


The carbene concentration in 1-ethyl-3-methylimidazolium-acetate ionic liquid is sufficiently high to act as a catalyst in benzoin condensation, hydroacylation and also in oxidation of an alcohol by using CO(2) and air. This observation reveals the potential of ionic liquid organocatalysts, uniting the beneficial properties of these two families of compounds. PMID:21701727

Kelemen, Zsolt; Hollóczki, Oldamur; Nagy, József; Nyulászi, László



Effect of cervical and vaginal insemination with liquid semen stored at room temperature on fertility of goats  

Microsoft Academic Search

The effect of vaginal and cervical deposition of liquid semen stored at room temperature on the fertility of goats was tested in a field trial in which 217 Norwegian Dairy goats aged between 6 months and 7.5 years from 14 farms were inseminated after natural oestrous. Cervical insemination with 200 × 106 spermatozoa resulted in 25-day non-return and kidding rates

H. Paulenz; L. Söderquist; T. Ådnøy; K. Soltun; P. A. Sæther; K. R. Fjellsøy; K. Andersen Berg



Splashing phenomena of room temperature liquid metal droplet striking on the pool of the same liquid under ambient air environment  

E-print Network

In this article, the fluid dynamics of room temperature liquid metal (RTLM) droplet impacting onto a pool of the same liquid in ambient air was investigated. A series of experiments were conducted in order to disclose the influence of the oxidation effect on the impact dynamics. The droplet shape and impact phenomenology were recorded with the aid of a high-speed digital camera. The impact energy stored in the splash structures was estimated via a theoretical model and several morphological parameters obtained from instantaneous images of the splash. It was observed that the droplet shape and the splashing morphology of RTLM were drastically different from those of water, so was the impact dynamics between room temperature LM pool and high temperature LM pool. The energy analysis disclosed that the height of the jet is highly sensitive to the viscosity of the fluid, which is subjected to the oxidation effect and temperature effect simultaneously, and thus perfectly explained the phenomena. These basic findings are important for the application of RTLM in a series of newly emerging technologies such as liquid metal based spray cooling, ink-jet printed electronics, interface material painting and coating, metallurgy, and 3D packages, etc.

Haiyan Li; Shengfu Mei; Lei Wang; Yunxia Gao; Jing Liu



A new class of room temperature molten salts for battery applications  

Microsoft Academic Search

Salts that are liquid at room temperature would provide a completely ionic electrolyte for rechargeable batteries without the penalty of high operating temperatures. We have discovered and characterized a new class of molten salts that are liquids considerably below room temperature. The new materials are mixtures of dialkyimidazolium chlorides and aluminum chloride. The solid-liquid phase diagram of one member of

J. S. Wilkes; J. A. Levisky; J. S. Landers; R. L. Vaughn; C. L. Hussey; D. A. Floreani; D. J. Stech



Applications of ionic liquids.  


Ionic liquids have recently gained popularity in the scientific community owing to their special properties and characteristics. One of the reasons why ionic liquids have been termed "green solvents" is due to their negligible vapour pressure. Their use in electrochemical, biological and metal extraction applications is discussed. Wide research has been carried out for their use in batteries, solar panels, fuel cells, drug deliveries and biomass pretreatments. This work aims to consolidate the various findings from previous works in these areas. PMID:22711528

Patel, Divia Dinesh; Lee, Jong-Min



Thermodynamics and cell chemistry of room temperature sodium/sulfur cells with liquid and liquid/solid electrolyte  

NASA Astrophysics Data System (ADS)

The cell chemistry of sodium/sulfur cells operating at room temperature (RT-Na/S cells) is being studied electrochemically and structurally. We show by means of X-ray photoelectron spectroscopy that the cell reaction is incomplete but prove that the end members of the cell reaction (S and Na2S) form among the expected polysulfide species Na2Sx. The sulfur utilization can be improved by employing a solid electrolyte membrane (beta?-alumina) that prevents the diffusion of the soluble polysulfide species toward the sodium side. As an important finding, the Na+ conduction within the solid electrolyte phase and across the two liquid/solid interfaces results in only small overpotentials. Nevertheless the utilization of sulfur in the present RT-Na/S (475 mAh g-1) cells is lower than the theoretical value (1675 mAh g-1). One probable reason is the chemical instability of the widely used PVDF binder. Also, the thermodynamic properties of RT-Na/S cells operating at room temperature are discussed and compared with the currently much more studied RT-Li/S cells.

Wenzel, Sebastian; Metelmann, Hauke; Raiß, Christine; Dürr, Anna Katharina; Janek, Jürgen; Adelhelm, Philipp



Ionic liquids catalyzed Biginelli reaction under solvent-free conditions  

Microsoft Academic Search

3,4-Dihydropyrimidin-2(1H)-ones were synthesised in high yields by one-pot three-component Biginelli condensation in the presence of room temperature ionic liquids such as 1-n-butyl-3-methylimidazolium tetrafluoroborate (BMImBF4) or hexafluorophosphorate (BMImPF6) as catalysts under solvent-free and neutral conditions.

Jiajian Peng; Youquan Deng



Task specific ionic liquid for direct electrochemistry of metal oxides  

Microsoft Academic Search

We present the first report on task specific ionic liquid (TSIL) for direct electrochemical detection of heavy metal oxides including cadmium oxide, copper oxide and lead oxide at room temperature. This TSIL based electrochemical sensor demonstrated a high sensitivity and selectivity towards the online monitoring of these trace metal oxide particulates, along with short detection time, low cost and high

Donglai Lu; Nasim Shomali; Amy Shen



A general design platform for ionic liquid ions based on bridged multi-heterocycles with flexible symmetry and charge.  


A conceptual design platform for new ionic liquids with variable heterocycles, bridges, symmetry, and charge was developed using simple alkylation, click, and ionic liquid chemistries and demonstrated with 1-(2-(5-tetrazolidyl)ethyl)-3-(5-1H-tetrazolyl)methylimidazolium and its conversion into room-temperature ionic liquids as cation or as anion. PMID:20582354

Drab, David M; Shamshina, Julia L; Smiglak, Marcin; Hines, C Corey; Cordes, David B; Rogers, Robin D



Phase-Changing Ionic Liquids: CO2 Capture with Ionic Liquids Involving Phase Change  

SciTech Connect

IMPACCT Project: Notre Dame is developing a new CO2 capture process that uses special ionic liquids (ILs) to remove CO2 from the gas exhaust of coal-fired power plants. ILs are salts that are normally liquid at room temperature, but Notre Dame has discovered a new class of ILs that are solid at room temperature and change to liquid when they bind to CO2. Upon heating, the CO2 is released for storage, and the ILs re-solidify and donate some of the heat generated in the process to facilitate further CO2 release. These new ILs can reduce the energy required to capture CO2 from the exhaust stream of a coal-fired power plant when compared to state-ofthe- art technology.




Electroplating Using Ionic Liquids  

NASA Astrophysics Data System (ADS)

Electroplating is a key technology in many large-scale industrial applications such as corrosion-resistant and decorative coatings. Issues with current aqueous processes, such as toxicity of reagents and low current efficiencies, can often be overcome by using ionic liquids, and this approach has turned ionometallurgy into a fast-growing area of research. This review outlines the interactions in ionic liquids that are responsible for the advantageous properties of these solvents in electroplating. It summarizes recent research in which these properties have been analyzed or exploited and highlights fundamental issues in research and technology that need to be addressed.

Abbott, Andrew P.; Frisch, Gero; Ryder, Karl S.



VOC and HAP recovery using ionic liquids  

SciTech Connect

During the manufacture of wood composites, paper, and to a lesser extent, lumber, large amounts of volatile organic compounds (VOCs) such as terpenes, formaldehyde, and methanol are emitted to air. Some of these compounds are hazardous air pollutants (HAPs). The air pollutants produced in the forest products industry are difficult to manage because the concentrations are very low. Presently, regenerative thermal oxidizers (RTOs and RCOs) are commonly used for the destruction of VOCs and HAPs. RTOs consume large amounts of natural gas to heat air and moisture. The combustion of natural gas generates increased CO2 and NOx, which have negative implications for global warming and air quality. The aforementioned problems are addressed by an absorption system containing a room-temperature ionic liquid (RTIL) as an absorbent. RTILs are salts, but are in liquid states at room temperature. RTILs, an emerging technology, are receiving much attention as replacements for organic solvents in industrial processes with significant cost and environmental benefits. Some of these processes include organic synthesis, extraction, and metal deposition. RTILs would be excellent absorbents for exhausts from wood products facilities because of their unique properties: no measurable vapor pressure, high solubility of wide range of organic compounds, thermal stability to 200°C (almost 400°F), and immisciblity with water. Room temperature ionic liquids were tested as possible absorbents. Four were imidizolium-based and were eight phosphonium-based. The imidizolium-based ionic liquids proved to be unstable at the conditions tested and in the presence of water. The phosphonium-based ionic liquids were stable. Most were good absorbents; however, cleaning the contaminates from the ionic liquids was problematic. This was overcome with a higher temperature (120°C) than originally proposed and a very low pressure (1 kPa. Absorption trials were conducted with tetradecy(trihexyl)phosphonium dicyanamide as the RTIL. It was determined that it has good absorption properties for methanol and ?-pinene, is thermally stable, and is relatively easy to synthesize. It has a density of 0.89 g/mL at 20°C and a molecular weight of 549.9 g/mol. Trials were conducted with a small absorption system and a larger absorption system. Methanol, formaldehyde, and other HAPs were absorbed well, nearly 100%. Acetaldehyde was difficult to capture. Total VOC capture, while satisfactory on methanol and ?-pinene in a lab system, was less than expected in the field, 60-80%. The inability to capture the broad spectrum of total organics is likely due to difficulties in cleaning them from the ionic liquid rather than the ability of the ionic liquid to absorb. It’s likely that a commercial system could be constructed to remove 90 to 100% of the gas contaminates. Selecting the correct ionic liquid would be key to this. Absorption may not be the main selection criterion, but rather how easily the ionic liquid can be cleaned is very important. The ionic liquid absorption system might work very well in a system with a limited spectrum of pollutants, such as a paint spray line, where there are not very high molecular weight, non volatile, compounds in the exhaust.

Michael R. Milota : Kaichang Li



Application of ionic liquids as plasticizers for poly(methyl methacrylate).  


The room temperature ionic liquid, 1-butyl-3-methylimidazolium hexafluorophosphate, [C4mim][PF6] was found to be an efficient plasticizer for poly(methyl methacrylate), prepared by in situ radical polymerization in the ionic liquid medium; the polymers have physical characteristics comparable with those containing traditional plasticizers and retain greater thermal stability. PMID:12125560

Scott, Mark P; Brazel, Christopher S; Benton, Michael G; Mays, Jimmy W; Holbrey, John D; Rogers, Robin D



Hydrophobic ionic liquids  

Microsoft Academic Search

Ionic liquids having improved properties for application in non-aqueous batteries, electrochemical capacitors, electroplating, catalysis and chemical separations are disclosed. Exemplary compounds have one of the following formulas shown in a diagram wherein Râ, Râ, Râ, Râ, Râ, and Râ are either H; F; separate alkyl groups of from 1 to 4 carbon atoms, respectively, or joined together to constitute a

V. R. Koch; C. Nanjundiah; R. T. Carlin



Photopolymerization Sensitized by CdTe Nanocrystals in Ionic Liquid: Highly Efficient Photoinduced Electron Transfer  

Microsoft Academic Search

We demonstrate a photopolymerization sensitized by CdTe nanocrystals in room temperature ionic liquid. The kinetics of photoinduced electron transfer from cationic CdTe nanocrystals to polymerization initiators in several kinds of ionic liquids is also studied. From the analyses of photoluminescence quenching measurement, the electron transfer rates from CdTe nanocrystals to organic electron acceptors are anomalously large in the ionic liquid

Yoshiyuki Nonoguchi; Takuya Nakashima; Makiko Sakashita; Tsuyoshi Kawai



Cyclic phosphonium ionic liquids.  


Ionic liquids (ILs) incorporating cyclic phosphonium cations are a novel category of materials. We report here on the synthesis and characterization of four new cyclic phosphonium bis(trifluoromethylsulfonyl)amide ILs with aliphatic and aromatic pendant groups. In addition to the syntheses of these novel materials, we report on a comparison of their properties with their ammonium congeners. These exemplars are slightly less conductive and have slightly smaller self-diffusion coefficients than their cyclic ammonium congeners. PMID:24605146

Lall-Ramnarine, Sharon I; Mukhlall, Joshua A; Wishart, James F; Engel, Robert R; Romeo, Alicia R; Gohdo, Masao; Ramati, Sharon; Berman, Marc; Suarez, Sophia N



Hydrophobic ionic liquids  

Microsoft Academic Search

Ionic liquids having improved properties for application in non-aqueous batteries, electrochemical capacitors, electroplating, catalysis and chemical separations are disclosed. Exemplary compounds have one of the following formulas: ##STR1## wherein R.sub.1, R.sub.2, R.sub.3, R.sub.4, R.sub.5, and R.sub.6 are either H; F; separate alkyl groups of from 1 to 4 carbon atoms, respectively, or joined together to constitute a unitary alkylene radical

Victor R. Koch; Chenniah Nanjundiah; Richard T. Carlin



Switching from water to ionic liquids for the production of methylchloride: Catalysis and reactor issues  

Microsoft Academic Search

The synthesis of methyl chloride from methanol and hydrogen chloride catalysed by zinc chloride was investigated in water and in two room temperature ionic liquids in a CSTR reactor. Both Aliquat336 and BMICl drive to similar rate of reactions as the traditional process albeit at lower temperatures. More importantly, the formation of the side product Me2O is decreased in ionic

Nicolas Dupont; Pierre Grenouillet; Frédéric Bornette; Claude de Bellefon



New room-temperature thermotropic perylene-based bisimides: Synthesis, liquid crystalline, light-emitting and electrochemical properties  

NASA Astrophysics Data System (ADS)

Three N-alkoxy-substituted perylene-3,4,9,10-tetracarboxyldiimides (PBIs) were synthesized and characterized through the data from 1H nuclear magnetic resonance (NMR), infrared spectroscopy (IR), elemental analysis, UV-vis absorption spectroscopy, photoluminescence (PL), cyclic voltammetry (CV) and differential pulse voltammetry (DPV) measurements. The phase behavior of obtained bisimides was examined by differential scanning calorimetry (DSC) and polarized optical microscopy (POM). They possess liquid crystalline properties at room temperature and a single mesophase structure exists in wide range of temperatures. The presented bisimides are well soluble in common solvents. All of them are highly fluorescent in solution and in solid state as blend with PMMA. The electrochemical band gap energy (Eg), LUMO and HOMO energy values were in the range 1.46-2.11 eV, -3.74 to -3.98 V and -5.38 to -5.96 V, respectively.

Bijak, Katarzyna; Janeczek, Henryk; Grucela-Zajac, Marzena; Schab-Balcerzak, Ewa



Invited Review Raman Spectroscopy and Ab-Initio Model Calculations on Ionic Liquids  

Microsoft Academic Search

Summary. A review of the recent developments in the study and understanding of room temperature ionic liquids are given. An intimate picture of how and why these liquids are not crystals at ambient conditions is attempted, based on evidence from crystallographical results combined with vibra- tional spectroscopy and ab-initio molecular orbital calcula- tions. A discussion is given, based mainly on

Rolf W. Berg



Polarization versus Temperature in Pyridinium Ionic Liquids  

E-print Network

Electronic polarization and charge transfer effects play a crucial role in thermodynamic, structural and transport properties of room-temperature ionic liquids (RTILs). These non-additive interactions constitute a useful tool for tuning physical chemical behavior of RTILs. Polarization and charge transfer generally decay as temperature increases, although their presence should be expected over an entire condensed state temperature range. For the first time, we use three popular pyridinium-based RTILs to investigate temperature dependence of electronic polarization in RTILs. Atom-centered density matrix propagation molecular dynamics, supplemented by a weak coupling to an external bath, is used to simulate the temperature impact on system properties. We show that, quite surprisingly, non-additivity in the cation-anion interactions changes negligibly between 300 and 900 K, while the average dipole moment increases due to thermal fluctuations of geometries. Our results contribute to the fundamental understanding...

Chaban, Vitaly V



Low-melting mixtures based on choline ionic liquids.  


In this article a strategy is proposed for the design of low toxic, room temperature liquid low-melting mixtures (LMMs) which are entirely composed of natural materials. From literature it is well known that, in general, deep eutectic solvents based on choline chloride and dicarboxylic acids are LMMs, but not liquids at room temperature, with one exception: a 1?:?1 molar mixture of malonic acid and choline chloride. Therefore, the starting point of this study was the decrease of the melting point of one of the components, namely the dicarboxylic acid, which is succinic, glutaric or adipic acid. For this purpose, one of the two protons of the acidic group was exchanged by a bulky unsymmetrical choline cation. The resulting ionic liquids (ILs) were still solid at room temperature, but have a reduced melting temperature compared to the corresponding acids. In the second step, mixtures of these ILs with choline chloride were prepared. It turned out that choline glutarate-choline chloride mixtures are liquids at room temperature at compositions containing 95-98 wt% of choline glutarate. Finally, urea was added as another hydrogen bond donor. Density, conductivity and viscosity measurements were performed for all obtained mixtures. Moreover, a Walden plot was drawn which indicates that all mixtures are liquids with fully dissociated ions moving independently. Therefore, they are considered as "good" ionic liquids and, thus, for example they can be used to exchange more toxic or less biodegradable ILs in application processes. A brief outlook containing application possibilities is given. It is demonstrated that choline dodecylsulfate is readily soluble in these mixtures, forming aggregates in the LMM at temperatures exceeding 55 °C. PMID:25242504

Rengstl, Doris; Fischer, Veronika; Kunz, Werner



An unusual slowdown of fast diffusion in a room temperature  

SciTech Connect

Using quasielastic neutron scattering in the temperature range from 290 to 350 K, we show that the diffusive motions in a room temperature ionic liquid [H2NC(dma)2][BETI] become faster for a fraction of cations when the liquid is confined in a mesoporous carbon. This applies to both the localized and long-range translational diffusive motions of the highly mobile cations, although the former exhibit an unusual trend of slowing-down as the temperature is increased, until the localized diffusivity is reduced to the bulk ionic liquid value at a temperature of 350 K.

Chathoth, [Oak Ridge National Laboratory (ORNL); Mamontov, Eugene [ORNL; Fulvio, Pasquale F [ORNL; Wang, Xin [ORNL



Physical and electrochemical properties of thioether-functionalized ionic liquids.  


The preparation and characterization of a series of ionic liquids based on S-alkyl thiolonium, S-alkyl thiotetrazolium, or S-alkyl thiobenzolium cations coupled with bis(trifluoromethanesulfonyl)amide, trifluoromethanesulfonate, alkyl phosphate, chloride, and hexafluorophosphate anions are reported. All are liquid at room temperature, except the chloride salt, which has a melting point of 92 degrees C. The electrochemical characteristics of this class of ionic liquid have been determined by cyclic voltammetry. Potential windows of the ionic liquids have been obtained at glassy carbon, platinum, and gold electrodes and found to be the largest at glassy carbon, but are limited by oxidation of the thioether-functionalized cation. The voltammetry of IUPAC reference potential scale systems, ferrocene/ferrocenium, cobaltocenium/cobaltocene, and decamethylferrocene/decamethylferrocenium have been evaluated, with the last being most widely applicable. Nonadditivity of Faradaic current is found in the voltammograms of decamethylferrocene in the presence of ferrocene and cobaltocenium. Diffusion coefficient, viscosity, ionic conductivity, double layer capacitance, and other physical properties have also been measured. The dependence of the diffusion coefficient vs viscosity follows the Stokes-Einstein relationship. The properties of the ionic liquids are compared with the related imidazolium family of ionic liquids. PMID:19627093

Torriero, Angel A J; Siriwardana, Amal I; Bond, Alan M; Burgar, Iko M; Dunlop, Noel F; Deacon, Glen B; MacFarlane, Douglas R



Novel applications of ionic liquids in materials processing  

NASA Astrophysics Data System (ADS)

Ionic liquids are mixtures of organic and inorganic salts which are liquids at room temperature. Several potential applications of ionic liquids in the field of materials processing are electrowinning and electrodeposition of metals and alloys, electrolysis of active metals at low temperature, liquid-liquid extraction of metals. Results using 1-butyl-3-methylimidazolium chloride with AlCl3 at low temperatures yielded high purity aluminium deposits (>99.9% pure) and current efficiencies >98%. Titanium and aluminium were co-deposited with/without the addition of TiCl4 with up to 27 wt% Ti in the deposit with current efficiencies in the range of 78-85 %. Certain ionic liquids are potential replacements for thermal oils and molten salts as heat transfer fluids in solar energy applications due to high thermal stability, very low corrosivity and substantial sensible heat retentivity. The calculated storage densities for several chloride and fluoride ionic liquids are in the range of 160-210 MJ/m3. A 3-D mathematical model was developed to simulate the large scale electrowinning of aluminium. Since ionic liquids processing results in their low energy consumption, low pollutant emissions many more materials processing applications are expected in future.

Reddy, Ramana G.



Ionic liquid of a gold nanocluster: a versatile matrix for electrochemical biosensors.  


Ionic liquids are room-temperature molten salts that are increasingly used in electrochemical devices, such as batteries, fuel cells, and sensors, where their intrinsic ionic conductivity is exploited. Here we demonstrate that combining anionic, redox-active Au25 clusters with imidazolium cations leads to a stable ionic liquid possessing both ionic and electronic conductivity. The Au25 ionic liquid was found to act as a versatile matrix for amperometric enzyme biosensors toward the detection of glucose. Enzyme electrodes prepared by incorporating glucose oxidase in the Au25 ionic liquid show high electrocatalytic activity and substrate affinity. Au25 clusters in the electrode were found to act as effective redox mediators as well as electronic conductors determining the detection sensitivity. With the unique electrochemical properties and almost unlimited structural tunability, the ionic liquids of quantum-sized gold clusters may serve as versatile matrices for a variety of electrochemical biosensors. PMID:24350837

Kwak, Kyuju; Kumar, S Senthil; Pyo, Kyunglim; Lee, Dongil



Novel zinc ion conducting polymer gel electrolytes based on ionic liquids  

Microsoft Academic Search

We report novel zinc ion conducting polymer gel electrolytes (PGEs) based on non-volatile room temperature ionic liquids. The PGEs consist of an ionic liquid, with a zinc salt dissolved in it, blended with a polymer matrix, poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP). The resultant electrolyte membranes are freestanding, translucent, flexible and elastic, with excellent mechanical integrity and strength. They possess exceptional thermal stability,

Jun John Xu; Hui Ye; Jian Huang



Ionic-liquid materials for the electrochemical challenges of the future  

Microsoft Academic Search

Ionic liquids are room-temperature molten salts, composed mostly of organic ions that may undergo almost unlimited structural variations. This review covers the newest aspects of ionic liquids in applications where their ion conductivity is exploited; as electrochemical solvents for metal\\/semiconductor electrodeposition, and as batteries and fuel cells where conventional media, organic solvents (in batteries) or water (in polymer-electrolyte-membrane fuel cells),

Michel Armand; Frank Endres; Douglas R. Macfarlane; Hiroyuki Ohno; Bruno Scrosati



Ionic Conductivity of Nanostructured Block Copolymer and Ionic Liquid Membranes  

Microsoft Academic Search

Block copolymer and ionic liquid mixtures are of interest for creating ionically conductive, thermally stable, and nanostructured membranes. For mixtures of poly(styrene-b-2-vinylpyridine) (S2VP) and the ionic liquid bis(trifluoromethanesulfonyl)imide ([Im][TFSI]), nanostructured ion-conducting domains are formed due to [Im][TFSI] selectively residing in the P2VP domains of the block copolymer. The dependence of ionic conductivity on temperature, ionic liquid loading, and volume fraction

Megan L. Hoarfrost; Justin M. Virgili; Rachel A. Segalman



Novel bipyridinium ionic liquids as liquid electrochromic devices.  


Novel mono and dialkylbipyridinium (viologens) cations combined with iodide, bromide, or bis(trifluoromethanesulfonyl)imide [NTf2] as anions were developed. Selective alkylation synthetic methodologies were optimized in order to obtain the desired salts in moderate to high yields and higher purities. All prepared mono- and dialkylbipyridinium salts were completely characterized by (1)H, (13)C, and (19)F?NMR spectroscopy, Fourier-transform IR spectroscopy, and elemental analysis (in the case of NTf2 salts). Melting points, glass transition temperatures by differential scanning calorimetry (DSC) studies, and decomposition temperatures were also checked for different prepared organic salts. Viscosities at specific temperatures and activation energies were determined by rheological studies (including viscosity dependence with temperature in heating and cooling processes). Electrochemical studies based on cyclic voltammetry (CV), differential pulsed voltammetry (DPV), and square-wave voltammetry (SWV) were performed in order to determine the redox potential as well as evaluate reversibility behavior of the novel bipyridinium salts. As proof of concept, we developed a reversible liquid electrochromic device in the form of a U-tube system, the most promising dialkylbipyridinium-NTf2 ionic liquid being used as the electrochromic material and the room-temperature ionic liquid (RTIL), 1-ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)-imide [EMIM][NTf2], as a stable and efficient electrolyte. PMID:24577754

Jordão, Noémi; Cabrita, Luis; Pina, Fernando; Branco, Luís C



Ionic Liquid Membranes for Carbon Dioxide Separation  

SciTech Connect

Recent scientific studies are rapidly advancing novel technological improvements and engineering developments that demonstrate the ability to minimize, eliminate, or facilitate the removal of various contaminants and green house gas emissions in power generation. The Integrated Gasification Combined Cycle (IGCC) shows promise for carbon dioxide mitigation not only because of its higher efficiency as compared to conventional coal firing plants, but also due to a higher driving force in the form of high partial pressure. One of the novel technological concepts currently being developed and investigated is membranes for carbon dioxide (CO2) separation, due to simplicity and ease of scaling. A challenge in using membranes for CO2 capture in IGCC is the possibility of failure at elevated temperatures or pressures. Our earlier research studies examined the use of ionic liquids on various supports for CO2 separation over the temperature range, 37°C-300°C. The ionic liquid, 1-hexyl-3methylimidazolium Bis(trifluoromethylsulfonyl)imide, ([hmim][Tf2N]), was chosen for our initial studies with the following supports: polysulfone (PSF), poly(ether sulfone) (PES), and cross-linked nylon. The PSF and PES supports had similar performance at room temperature, but increasing temperature caused the supported membranes to fail. The ionic liquid with the PES support greatly affected the glass transition temperature, while with the PSF, the glass transition temperature was only slightly depressed. The cross-linked nylon support maintained performance without degradation over the temperature range 37-300°C with respect to its permeability and selectivity. However, while the cross-linked nylon support was able to withstand temperatures, the permeability continued to increase and the selectivity decreased with increasing temperature. Our studies indicated that further testing should examine the use of other ionic liquids, including those that form chemical complexes with CO2 based on amine interactions. The hypothesis is that the performance at the elevated temperatures could be improved by allowing a facilitated transport mechanism to become dominant. Several amine-based ionic liquids were tested on the cross-linked nylon support. It was found that using the amine-based ionic liquid did improve selectivity and permeability at higher temperature. The hypothesis was confirmed, and it was determined that the type of amine used also played a role in facilitated transport. Given the appropriate aminated ionic liquid with the cross-linked nylon support, it is possible to have a membrane capable of separating CO2 at IGCC conditions. With this being the case, the research has expanded to include separation of other constituents besides CO2 (CO, H2S, etc.) and if they play a role in membrane poisoning or degradation. This communication will discuss the operation of the recently fabricated ionic liquid membranes and the impact of gaseous components other than CO2 on their performance and stability.

Myers, C.R.; Ilconich, J.B.; Luebke, D.R.; Pennline, H.W.



Influence of chloride, water, and organic solvents on the physical properties of ionic liquids  

Microsoft Academic Search

We report here the first systematic study of the effect of impurities and additives (e.g., water, chloride, and cosolvents) on the physical properties of room-temperature ionic liquids. Remarkably, it was discovered that the viscosity of mixtures was dependent mainly on the mole fraction of added molecular solvents and only to a lesser extent upon their iden- tity, allowing viscosity changes

Kenneth R. Seddon; Annegret Stark; María-José Torres



Ionic liquid as an efficient promoting medium for two-phase nucleophilic displacement reactions  

Microsoft Academic Search

The use of the room temperature ionic liquid (RTIL) 1-n-butyl-3-methylimidazolium hexafluorophosphate as an efficient catalyst and solvent for several representative nucleophilic substitution reactions under aqueous-RTIL phase transfer conditions was explored. Recycling and reuse of the reaction medium was demonstrated for the azide formation.

Nuno M. T Lourenço; Carlos A. M Afonso



Glass transition of ionic liquids under high pressure.  


The glass transition pressure at room temperature, pg, of six ionic liquids based on 1-alkyl-3-methylimidazolium cations and the anions [BF4](-), [PF6](-), and bis(trifluromethanesulfonyl)imide, [NTf2](-), has been obtained from the pressure dependence of the bandwidth of the ruby fluorescence line in diamond anvil cells. Molar volume, Vm(pg), has been estimated by a group contribution model (GCM) developed for the ionic liquids. A density scaling relation, TV(?), has been considered for the states Vm(pg, 295?K) and Vm(Tg, 0.1 MPa) using the simplifying condition that the viscosity at the glass transition is the same at pg at room temperature and at atmospheric pressure at Tg. Assuming a constant ? over this range of density, a reasonable agreement has been found for the ? determined herein and that of a previous density scaling analysis of ionic liquids viscosities under moderate conditions. Further support for the appropriateness of extrapolating the GCM equation of state to the GPa pressure range is provided by comparing the GCM and an equation of state previously derived in the power law density-scaling regime. PMID:24985661

Ribeiro, Mauro C C; Pádua, Agílio A H; Gomes, Margarida F Costa



Selective extraction of copper, mercury, silver and palladium ionsfrom water using hydrophobic ionic liquids.  

SciTech Connect

Extraction of dilute metal ions from water was performed near room temperature with a variety of ionic liquids. Distribution coefficients are reported for fourteen metal ions extracted with ionic liquids containing cations 1-octyl-4-methylpyridinium [4MOPYR]{sup +}, 1-methyl-1-octylpyrrolidinium [MOPYRRO]{sup +} or 1-methyl-1-octylpiperidinium [MOPIP]{sup +}, and anions tetrafluoroborate [BF{sub 4}]{sup +}, trifluoromethyl sulfonate [TfO]{sup +} or nonafluorobutyl sulfonate [NfO]{sup +}. Ionic liquids containing octylpyridinium cations are very good for extracting mercury ions. However, other metal ions were not significantly extracted by any of these ionic liquids. Extractions were also performed with four new task-specific ionic liquids. Such liquids containing a disulfide functional group are efficient and selective for mercury and copper, whereas those containing a nitrile functional group are efficient and selective for silver and palladium.

Papaiconomou, Nicolas; Lee, Jong-Min; Salminen, Justin; VonStosch, Moritz; Prausnitz, John M.



Gas-liquid interface-mediated room-temperature synthesis of "clean" PdNiP alloy nanoparticle networks with high catalytic activity for ethanol oxidation.  


PdNiP alloy nanoparticle networks (PdNiP NN) were prepared by simultaneous reduction of PdCl2, NiCl2 and NaH2PO2 with NaBH4via a gas-liquid interface reaction at room temperature using N2 bubbles. PdNiP NN had markedly higher activity and durability for ethanol oxidation than PdNi nanoparticle networks and PdNiP grain aggregates. PMID:25213875

Wang, Rongfang; Ma, Yuanyuan; Wang, Hui; Key, Julian; Ji, Shan



Room Temperature Ionic Liquid-Lithium Salt Mixtures: Optical Kerr Effect Dynamical Measurements  

E-print Network

optical Kerr effect spectroscopy was used to study the change in dynamics, principally orientational derivative of the polarizability-polarizability correlation function (second Legendre polynomial correlation function), is used to probe the orientational dynamics of pure 1-butyl-3-methylimidazolium bis

Fayer, Michael D.


Synthesis and anti-microbial activity of hydroxylammonium ionic liquids.  


Eight hydroxylammonium-based room temperature ionic liquids (ILs) have been synthesized by acid-base neutralization of ethanolamines with organic acids. The ILs were characterized by infrared and nuclear magnetic resonance spectroscopies and elemental analysis. Their anti-microbial activities were determined using the well-diffusion method. All eight ILs were toxic to Staphylococcus aureus, while 2-hydroxyethylammonium lactate and 2-hydroxy-N-(2-hydroxyethyl)-N-methylethanaminium acetate showed high anti-microbial activity against a wide range of human pathogens. PMID:21421256

Ismail Hossain, M; El-Harbawi, Mohanad; Noaman, Yousr Abdulhadi; Bustam, Mohd Azmi B; Alitheen, Noorjahan Banu Mohamed; Affandi, Nor Azrin; Hefter, Glenn; Yin, Chun-Yang



Ionic-liquid materials for the electrochemical challenges of the future  

NASA Astrophysics Data System (ADS)

Ionic liquids are room-temperature molten salts, composed mostly of organic ions that may undergo almost unlimited structural variations. This review covers the newest aspects of ionic liquids in applications where their ion conductivity is exploited; as electrochemical solvents for metal/semiconductor electrodeposition, and as batteries and fuel cells where conventional media, organic solvents (in batteries) or water (in polymer-electrolyte-membrane fuel cells), fail. Biology and biomimetic processes in ionic liquids are also discussed. In these decidedly different materials, some enzymes show activity that is not exhibited in more traditional systems, creating huge potential for bioinspired catalysis and biofuel cells. Our goal in this review is to survey the recent key developments and issues within ionic-liquid research in these areas. As well as informing materials scientists, we hope to generate interest in the wider community and encourage others to make use of ionic liquids in tackling scientific challenges.

Armand, Michel; Endres, Frank; Macfarlane, Douglas R.; Ohno, Hiroyuki; Scrosati, Bruno



Ionic-liquid materials for the electrochemical challenges of the future.  


Ionic liquids are room-temperature molten salts, composed mostly of organic ions that may undergo almost unlimited structural variations. This review covers the newest aspects of ionic liquids in applications where their ion conductivity is exploited; as electrochemical solvents for metal/semiconductor electrodeposition, and as batteries and fuel cells where conventional media, organic solvents (in batteries) or water (in polymer-electrolyte-membrane fuel cells), fail. Biology and biomimetic processes in ionic liquids are also discussed. In these decidedly different materials, some enzymes show activity that is not exhibited in more traditional systems, creating huge potential for bioinspired catalysis and biofuel cells. Our goal in this review is to survey the recent key developments and issues within ionic-liquid research in these areas. As well as informing materials scientists, we hope to generate interest in the wider community and encourage others to make use of ionic liquids in tackling scientific challenges. PMID:19629083

Armand, Michel; Endres, Frank; MacFarlane, Douglas R; Ohno, Hiroyuki; Scrosati, Bruno



Stable and water-tolerant ionic liquid ferrofluids.  


Ionic liquid ferrofluids have been prepared containing both bare and sterically stabilized 8-12 nm diameter superparamagnetic iron oxide nanoparticles, which remain stable for several months in both protic ethylammonium and aprotic imidazolium room-temperature ionic liquids. These ferrofluids exhibit spiking in static magnetic fields similar to conventional aqueous and nonaqueous ferrofluids. Ferrofluid stability was verified by following the flocculation and settling behavior of dilute nanoparticle dispersions. Although bare nanoparticles showed excellent stability in some ILs, they were unstable in others, and exhibited limited water tolerance. Stability was achieved by incorporating a thin polymeric steric stabilization layer designed to be compatible with the IL. This confers the added benefit of imbuing the ILF with a high tolerance to water. PMID:21338083

Jain, Nirmesh; Zhang, Xiaoli; Hawkett, Brian S; Warr, Gregory G



Electrodeposition of magnesium film from BMIMBF 4 ionic liquid  

NASA Astrophysics Data System (ADS)

In this paper, we reported for the first time magnesium electrodeposition and dissolution processes in the ionic liquid of BMIMBF 4 with 1 M Mg(CF 3SO 3) 2 at room temperature. Our study found that complete electrochemical reoxidation of the electrodeposited magnesium film was feasible only on Ag substrate, comparing with the Pt, Ni, and stainless-steel. Scanning electron microscope (SEM) and energy dispersive spectroscopy (EDS) results showed that magnesium was found in the deposited film and the deposits were dense. The electrodeposition of magnesium on Ag substrate in the ionic liquid was considered to be a reversible process by cyclic voltammetry. Plots of peak current versus the square root of the scan rate were found to be linear, which indicates that the mass-transport process of electroactive species was mainly diffusion controlled. The diffusion coefficient D values of electroactive species were calculated from cyclic voltammetry and chronoamperometry, respectively.

NuLi, Yanna; Yang, Jun; Wang, Pu



Designing Imidazole-Based Ionic Liquids and Ionic Liquid Monomers for Emerging Technologies  

Microsoft Academic Search

Imidazolium-based ionic liquids and ionic liquid monomers are becoming increasingly popular in a variety of areas including biphasic reaction catalysis, electromechanical actuator membranes and diluents, separation science membranes, and water purification agents. Ionic liquids first incorporated the imidazole ring in 1984 and this heterocyclic ring has emerged as the focal point of the ionic liquid field. Imidazole was targeted for

Matthew D. Green; Timothy E. Long



On the concept of ionicity in ionic liquids.  


Ionic liquids are liquids comprised totally of ions. However, not all of the ions present appear to be available to participate in conduction processes, to a degree that is dependent on the nature of the ionic liquid and its structure. There is much interest in quantifying and understanding this 'degree of ionicity' phenomenon. In this paper we present transport data for a range of ionic liquids and evaluate the data firstly in terms of the Walden plot as an approximate and readily accessible approach to estimating ionicity. An adjusted Walden plot that makes explicit allowance for differences in ion sizes is shown to be an improvement to this approach for the series of ionic liquids described. In some cases, where diffusion measurements are possible, it is feasible to directly quantify ionicity via the Nernst-Einstein equation, confirming the validity of the adjusted Walden plot approach. Some of the ionic liquids studied exhibit ionicity values very close to ideal; this is discussed in terms of a model of a highly associated liquid in which the ion correlations have similar impact on both the diffusive and conductive motions. Ionicity, as defined, is thus a useful measure of adherence to the Nernst-Einstein equation, but is not necessarily a measure of ion availability in the chemical sense. PMID:19562126

MacFarlane, Douglas R; Forsyth, Maria; Izgorodina, Ekaterina I; Abbott, Andrew P; Annat, Gary; Fraser, Kevin



Liquids intermediate between "molecular" and "ionic" liquids: liquid ion pairs?  


Ionic liquids comprised of tetradecyltrihexyl- and tetrabutyl-phosphonium cations paired with chloride or sulfonyl amide anions exhibit properties that reflect strong ion association, including comparatively low viscosity as well as a degree of volatility, and hence exemplify an interesting intermediate state between true ionic and true molecular liquids. PMID:18217657

Fraser, Kevin J; Izgorodina, Ekaterina I; Forsyth, Maria; Scott, Janet L; MacFarlane, Douglas R



Raman Spectroscopy and Ab-Initio Model Calculations on Ionic Liquids  

Microsoft Academic Search

Summary.  A review of the recent developments in the study and understanding of room temperature ionic liquids are given. An intimate\\u000a picture of how and why these liquids are not crystals at ambient conditions is attempted, based on evidence from crystallographical\\u000a results combined with vibrational spectroscopy and ab-initio molecular orbital calculations. A discussion is given, based mainly on some recent FT-Raman

Rolf W. Berg



Ionic liquids as lubricants of metal-polymer contacts. Preparation and properties of the first dispersions of ionic liquids and nanoparticles in polymers  

Microsoft Academic Search

Room-temperature ionic liquids (ILs) are high performance fluids that stand out because of a wide range of functional properties and exhibit a great potential for engineering applications. Although they have been employed as lubricants in metal-metal, metal-ceramic and ceramic-ceramic contacts, in this thesis we present the first study about the use of ILs as pure lubricants in polymer\\/steel contacts. The

Jose Sanes Molina



Low Temperature Reduction of Alumina Using Fluorine Containing Ionic Liquids  

SciTech Connect

The major objective of the project is to establish the feasibility of using specific ionic liquids capable of sustaining aluminum electrolysis near room temperature at laboratory and batch recirculation scales. It will explore new technologies for aluminum and other valuable metal extraction and process methods. The new technology will overcome many of the limitations associated with high temperatures processes such as high energy consumption and corrosion attack. Furthermore, ionic liquids are non-toxic and could be recycled after purification, thus minimizing extraction reagent losses and environmental pollutant emissions. Ionic liquids are mixture of inorganic and organic salts which are liquid at room temperature and have wide operational temperature range. During the last several years, they were emerging as novel electrolytes for extracting and refining of aluminum metals and/or alloys, which are otherwise impossible using aqueous media. The superior high temperature characteristics and high solvating capabilities of ionic liquids provide a unique solution to high temperature organic solvent problems associated with device internal pressure build-up, corrosion, and thermal stability. However their applications have not yet been fully implemented due to the insufficient understanding of the electrochemical mechanisms involved in processing of aluminum with ionic liquids. Laboratory aluminum electrodeposition in ionic liquids has been investigated in chloride and bis (trifluoromethylsulfonyl) imide based ionic liquids. The electrowinning process yielded current density in the range of 200-500 A/m2, and current efficiency of about 90%. The results indicated that high purity aluminum (>99.99%) can be obtained as cathodic deposits. Cyclic voltammetry and chronoamperometry studies have shown that initial stages of aluminum electrodeposition in ionic liquid electrolyte at 30°C was found to be quasi-reversible, with the charge transfer coefficient (0.40). Nucleation phenomena involved in aluminum deposition on copper in AlCl3-BMIMCl electrolyte was found to be instantaneous followed by diffusion controlled three-dimensional growth of nuclei. Diffusion coefficient (Do) of the electroactive species Al2Cl7¯ ion was in the range from 6.5 to 3.9×10–7 cm2?s–1 at a temperature of 30°C. Relatively little research efforts have been made toward the fundamental understanding and modeling of the species transport and transformation information involved in ionic liquid mixtures, which eventually could lead to quantification of electrochemical properties. Except that experimental work in this aspect usually is time consuming and expensive, certain characteristics of ionic liquids also made barriers for such analyses. Low vapor pressure and high viscosity make them not suitable for atomic absorption spectroscopic measurement. In addition, aluminum electrodeposition in ionic liquid electrolytes are considered to be governed by multi-component mass, heat and charge transport in laminar and turbulent flows that are often multi-phase due to the gas evolution at the electrodes. The kinetics of the electrochemical reactions is in general complex. Furthermore, the mass transfer boundary layer is about one order of magnitude smaller than the thermal and hydrodynamic boundary layer (Re=10,000). Other phenomena that frequently occur are side reactions and temperature or concentration driven natural convection. As a result of this complexity, quantitative knowledge of the local parameters (current densities, ion concentrations, electrical potential, temperature, etc.) is very difficult to obtain. This situation is a serious obstacle for improving the quality of products, efficiency of manufacturing and energy consumption. The gap between laboratory/batch scale processing with global process control and nanoscale deposit surface and materials specifications needs to be bridged. A breakthrough can only be realized if on each scale the occurring phenomena are understood and quantified. Multiscale numerical modeling nevertheless can help t

Dr. R. G. Reddy



Pressure and temperature effects on intermolecular vibrational dynamics of ionic liquids  

NASA Astrophysics Data System (ADS)

Low frequency Raman spectra of ionic liquids have been obtained as a function of pressure up to ca. 4.0 GPa at room temperature and as a function of temperature along the supercooled liquid and glassy state at atmospheric pressure. Intermolecular vibrations are observed at ~20, ~70, and ~100 cm-1 at room temperature in ionic liquids based on 1-alkyl-3-methylimidazolium cations. The component at ~100 cm-1 is assigned to librational motion of the imidazolium ring because it is absent in non-aromatic ionic liquids. There is a correspondence between the position of intermolecular vibrational modes in the normal liquid state and the spectral features that the Raman spectra exhibit after partial crystallization of samples at low temperatures or high pressures. The pressure-induced frequency shift of the librational mode is larger than the other two components that exhibit similar frequency shifts. The lowest frequency vibration observed in a glassy state corresponds to the boson peak observed in light and neutron scattering spectra of glass-formers. The frequency of the boson peak is not dependent on the length scale of polar/non-polar heterogeneity of ionic liquids, it depends instead on the strength of anion-cation interaction. As long as the boson peak is assigned to a mixing between localized modes and transverse acoustic excitations of high wavevectors, it is proposed that the other component observed in Raman spectra of ionic liquids has a partial character of longitudinal acoustic excitations.

Penna, Tatiana C.; Faria, Luiz F. O.; Matos, Jivaldo R.; Ribeiro, Mauro C. C.



Application of Ionic Liquids in Hydrometallurgy  

PubMed Central

Ionic liquids, low temperature molten salts, have various advantages manifesting themselves as durable and environmentally friendly solvents. Their application is expanding into various fields including hydrometallurgy due to their unique properties such as non-volatility, inflammability, low toxicity, good ionic conductivity, and wide electrochemical potential window. This paper reviews previous literatures and our recent results adopting ionic liquids in extraction, synthesis and processing of metals with an emphasis on the electrolysis of active/light, rare earth, and platinum group metals. Because the research and development of ionic liquids in this area are still emerging, various, more fundamental approaches are expected to popularize ionic liquids in the metal manufacturing industry. PMID:25177864

Park, Jesik; Jung, Yeojin; Kusumah, Priyandi; Lee, Jinyoung; Kwon, Kyungjung; Lee, Churl Kyoung



Radiation Chemistry and Photochemistry of Ionic Liquids  

SciTech Connect

As our understanding of ionic liquids and their tunable properties has grown, it is possible to see many opportunities for ionic liquids to contribute to the sustainable use of energy. The potential safety and environmental benefits of ionic liquids, as compared to conventional solvents, have attracted interest in their use as processing media for the nuclear fuel cycle. Therefore, an understanding of the interactions of ionizing radiation and photons with ionic liquids is strongly needed. However, the radiation chemistry of ionic liquids is still a relatively unexplored topic although there has been a significant increase in the number of researchers in the field recently. This article provides a brief introduction to ionic liquids and their interesting properties, and recent advances in the radiation chemistry and photochemistry of ionic liquids. In this article, we will mainly focus on excess electron dynamics and radical reaction dynamics. Because solvation dynamics processes in ionic liquids are much slower than in molecular solvents, one of the distinguishing characteristics is that pre-solvated electrons play an important role in ionic liquid radiolysis. It will be also shown that the reaction dynamics of radical ions is significantly different from that observed in molecular solvents because of the Coulombic screening effects and electrostatic interactions in ionic liquids.

Wishart, J.F.; Takahaski, K.



Thermoelectric Potential of Polymer-Scaffolded Ionic Liquid Membranes  

NASA Astrophysics Data System (ADS)

Organic thin films have been viewed as potential thermoelectric (TE) materials, given their ease of fabrication, flexibility, cost effectiveness, and low thermal conductivity. However, their intrinsically low electrical conductivity is a main drawback which results in a relatively lower TE figure of merit for polymer-based TE materials than for inorganic materials. In this paper, a technique to enhance the ion transport properties of polymers through the introduction of ionic liquids is presented. The polymer is in the form of a nanofiber scaffold produced using the electrospinning technique. These fibers were then soaked in different ionic liquids based on substituted imidazolium such as 1-ethyl-3-methylimidazolium chloride or 1-butyl-3-methylimidazolium bromide. This method was applied to electrospun polyacrylonitrile and a mixture of polyvinyl alcohol and chitosan polymers. The ion transport properties of the membranes have been observed to increase with increasing concentration of ionic liquid, with maximum electrical conductivity of 1.20 × 10-1 S/cm measured at room temperature. Interestingly, the maximum electrical conductivity value surpassed the value of pure ionic liquids. These results indicate that it is possible to significantly improve the electrical conductivity of a polymer membrane through a simple and cost-effective method. This may in turn boost the TE figures of merit of polymer materials, which are well known to be considerably lower than those of inorganic materials. Results in terms of the Seebeck coefficient of the membranes are also presented in this paper to provide an overall representation of the TE potential of the polymer-scaffolded ionic liquid membranes.

Datta, R. S.; Said, S. M.; Sahamir, S. R.; Karim, M. R.; Sabri, M. F. M.; Nakajo, T.; Kubouchi, M.; Hayashi, K.; Miyazaki, Y.



Hydrophobic ionic liquids based on the 1-butyl-3-methylimidazolium cation for lithium\\/seawater batteries  

Microsoft Academic Search

Two hydrophobic ionic liquids (room temperature molten salts) based on 1-butyl-3-methylimidazolium cation (BMI+), BMI+PF6? and BMI+Tf2N?, were used in developing a highly efficient lithium anode system for lithium\\/seawater batteries. The lithium anode system was composed of lithium metal\\/ionic liquid\\/Celgard membrane. Both BMI+PF6?and BMI+Tf2N? maintained high apparent anodic efficiency (up to 100%) under potentiostatic polarization (at +0.5V versus open-circuit potential (OCP))

Yancheng Zhang; Mirna Urquidi-Macdonald



Design and synthesis of pyridinium chiral ionic liquids tethered to a urea functionality.  


Nine chiral room-temperature ionic liquids (RTILs), which contain a chiral moiety and a urea functionality bonded to a pyridinium ring, have been designed and synthesized. The synthesis of these ionic liquids is concise and practical due to the commercial availability of the starting materials. These novel RTILs were readily prepared from 2-(aminomethyl)pyridine and amino acid ester derived isocyanates. We envision that these new chiral RTILs can serve as effective reaction media as well as chiral catalysts for asymmetric reactions, which are presently being investigated in our laboratory. PMID:17168608

Ni, Bukuo; Zhang, Qianying; Headley, Allan D



Unexpected improvement in stability and utility of cytochrome c by solution in biocompatible ionic liquids.  


Proteins generally are only stable in vitro for short periods of time. This results in challenges during isolation and purification of recombinant proteins and reduces the shelf life of protein-based pharmaceuticals. Here we show that certain novel, biocompatible ionic liquids provide a stabilizing solvent for proteins, for example, cytochrome c, such that structure and activity are maintained even after 6 months of storage at room temperature. Normally, this protein would be rendered inactive after only 1 week in buffered aqueous solution. The effect of the ionic liquid solvent appears to be related to protection against hydrolysis. PMID:16615145

Fujita, Kyoko; Forsyth, Maria; MacFarlane, Douglas R; Reid, Robert W; Elliott, Gloria D



Electrochemical properties of novel ionic liquids for electric double layer capacitor applications  

Microsoft Academic Search

An aliphatic quaternary ammonium salt which has a methoxyethyl group on the nitrogen atom formed an ionic liquid (room temperature molten salt) when combined with the tetrafluoroborate (BF4?) and bis(trifluoromethylsulfonyl)imide [TFSI; (CF3SO2)2N?] anions. The limiting oxidation and reduction potentials, specific conductivity, and some other physicochemical properties of the novel ionic liquids, N,N-diethyl-N-methyl-N-(2-methoxyethyl)ammonium tetrafluoroborate (DEME-BF4) and DEME-TFSI have been evaluated and

Takaya Sato; Gen Masuda; Kentaro Takagi



Fast fully plastic actuator based on ionic-liquid-based bucky gel  

NASA Astrophysics Data System (ADS)

In previous papers, we reported the first dry actuator that can be fabricated simply by layer-by-layer casting, using 'bucky gel', a gelatinous room-temperature ionic liquid containing single-walled carbon nanotubes (SWNTs). The actuator has a bimorph configuration with a polymer-supported internal ionic liquid electrolyte layer sandwiched by polymer-supported bucky-gel electrode layers, which allow quick and long-lived operation in air at low applied voltages. In this paper, some of the recent developments of the actuator performance are reported.

Asaka, Kinji; Mukai, Ken; Takeuchi, Ichiroh; Kiyohara, Kenji; Sugino, Takushi; Terasawa, Naohiro; Hata, Kenji; Fukushima, Takanori; Aida, Takuzo



Solvent effect on the ion adsorption from ionic liquid electrolyte into sub-nanometer carbon pores  

Microsoft Academic Search

This paper presents the results from the investigation of the influence of ion size on the capacitance behaviour of TiC-derived carbon (CDC) powders in the ethyl-methylimmidazolium-bis(trifluoro-methane-sulfonyl)imide ionic liquid (EMI, TFSI) used as neat electrolyte at 60°C or as salt dissolved in acetonitrile and tested at room temperature. These studies were carried out with the assembly of conventional 3-electrode electrochemical cells

R. Lin; P. Huang; J. Ségalini; C. Largeot; P. L. Taberna; J. Chmiola; Y. Gogotsi; P. Simon



Aluminium electroplated from ionic liquids as protective coating against steel corrosion  

Microsoft Academic Search

The protective action of thin layers of aluminium electroplated on a carbon steel (UNI Fe360B) has been studied. The coatings were obtained via electroreduction, at room temperature, from an ionic liquid constituted by 1-butyl-3-methyl-imidazolium heptachloroaluminate. Coatings of different thickness, ranging from 10 to 40?m, were obtained. Their morphology and chemical composition were investigated using SEM microscopy coupled with EDX microanalysis

Stefano Caporali; Alessio Fossati; Alessandro Lavacchi; Ilaria Perissi; Alexander Tolstogouzov; Ugo Bardi



Preparation of europium (III) doped nanocrystalline zinc oxide in ionic liquid via an ultrasonic irradiation  

Microsoft Academic Search

In this work, europium (III) doped zinc oxide nanoparitcles have been successfully prepared in room temperature ionic liquid 1-butyl-3-methylimidazolium hexafluorophosphate (BmimPF6) via an ultrasonic irradiation. The doped nanocrystalline sample has been characterized by XRD and TEM techniques. A possible mechanism is proposed to explain the formation of Eu3+ doped ZnO nanomateirals. Additionally, the characteristic emissions of Eu3+ can be found

Yao Yang; Bin Gao; Yue-tao Yang; Xiao-jun Liu; Shu-yi Zhang



Synthesis of cadmium and zinc semiconductor compounds from an ionic liquid containing choline chloride and urea  

Microsoft Academic Search

A eutectic mixture of choline chloride and urea (commercially known as Reline) has been used as a medium from which CdS, CdSe, and ZnS thin films have been electrodeposited for the first time. Reline is a conductive room temperature ionic liquid (RTIL) with a wide electrochemical window, which is suitable for use as a medium for electrodeposition. The voltammetric behaviour

Phillip J. Dale; Anura P. Samantilleke; Dilip D. Shivagan; Laurence M. Peter



Extraction of copper and zinc-humic acid with an ionic liquid  

Microsoft Academic Search

Extraction of copper and zinc in the contaminated soil with a room temperature ionic liquid (RTIL) has been studied by X-ray absorption near edge structural (XANES) and X-ray absorption fine structural (EXAFS) spectroscopies in the present work. By the least-square fitted XANES spectra, the major copper and zinc species in the contaminated soil are adsorbed copper- and adsorbed zinc-humic acid

H.-L. Huang; Ru-Ling Tseng



Investigations into the Synthesis, Identification and Developability of Active Ionic Liquids  

E-print Network

ionic liquids are formed. 6 Experimental Chemicals used in the synthesis and characterization of AILs 1.0 N hydrochloric acid, citric acid, glacial acetic acid, succinic acid, acetonitrile, acetone, dichloromethane, and 85% phophoric acid... scale by adding molar equilivants of both counterions in a 250mL round bottom flask, and dissolving in 100 mL of solvent and stirring overnight at room temperature. The HCl salt of MK-A was reacted with glutamic acid, methanesulfonic acid, succinic...

Miller, Elise



Aza-Diels–Alder reactions in ionic liquids: a facile synthesis of pyrano- and furanoquinolines  

Microsoft Academic Search

Room temperature ionic liquids are found to catalyze efficiently the three component-coupling reactions of aldehydes, amines and cyclic enol ethers such as 3,4-dihydro-2H-pyran and 2,3-dihydrofuran under mild and convenient conditions to afford the corresponding pyrano- and furanoquinolines in excellent yields with high endo-selectivity. Interestingly, 2,3-dihydrofuran afforded selectively endo-products under the similar reaction conditions.

J. S Yadav; B. V. S Reddy; J. S. S Reddy; R. Srinivasa Rao



Diels-Alder reactions in chloroaluminate ionic liquids: acceleration and selectivity enhancement  

Microsoft Academic Search

The utility of room temperature chloroaluminate ionic liquids as solvent and catalyst for the synthetically important Diels-Alder reaction was studied. The AlCl3-1-ethyl-3-methyl-1H-imidazolium chloride medium proved to be ideally suited for Diels-Alder reactions. Endo selectivity and rate enhancement were observed for the cyclopentadiene\\/methyl acrylate Diels-Alder reaction.

Carlos W. Lee



Efficient intramolecular hydroalkoxylation/cyclization of unactivated alkenols mediated by lanthanide triflate ionic liquids.  


Lanthanide triflates, Ln(OTf)(3), serve as efficient catalysts for the intramolecular hydroalkoxylation (HO)/cyclization of primary/secondary and aliphatic/aromatic hydroxyalkenes in room temperature ionic liquids (RTILs). Cyclizations are effective in the formation of five- and six-membered oxygen heterocycles with Markovnikov-type selectivity. Reaction rates exhibit first-order dependence on [Ln(3+)] and [substrate]. PMID:19271730

Dzudza, Alma; Marks, Tobin J



Partition coefficients of organic compounds between water and imidazolium-, pyridinium-, and phosphonium-based ionic liquids.  


The partition coefficients, P IL/w, of several compounds, some of them of biological and pharmacological interest, between water and room-temperature ionic liquids based on the imidazolium, pyridinium, and phosphonium cations, namely 1-octyl-3-methylimidazolium hexafluorophosphate, N-octylpyridinium tetrafluorophosphate, trihexyl(tetradecyl)phosphonium chloride, trihexyl(tetradecyl)phosphonium bromide, trihexyl(tetradecyl)phosphonium bis(trifluoromethylsulfonyl)imide, and trihexyl(tetradecyl)phosphonium dicyanamide, were accurately measured. In this way, we extended our database of partition coefficients in room-temperature ionic liquids previously reported. We employed the solvation parameter model with different probe molecules (the training set) to elucidate the chemical interactions involved in the partition process and discussed the most relevant differences among the three types of ionic liquids. The multiparametric equations obtained with the aforementioned model were used to predict the partition coefficients for compounds (the test set) not present in the training set, most being of biological and pharmacological interest. An excellent agreement between calculated and experimental log P IL/w values was obtained. Thus, the obtained equations can be used to predict, a priori, the extraction efficiency for any compound using these ionic liquids as extraction solvents in liquid-liquid extractions. PMID:25326892

Padró, Juan M; Pellegrino Vidal, Rocío B; Reta, Mario



Vertical alignment of liquid crystal through ion beam exposure on oxygen-doped SiC films deposited at room temperature  

SciTech Connect

The authors report the vertical alignment of liquid crystal (LC) through the ion beam exposure on amorphous oxygen-doped SiC (SiOC) film surfaces deposited at room temperature. The optical transmittance of these films was similar to that of polyimide layers, but much higher than that of SiO{sub x} films. The light leakage of a LC cell aligned vertically on SiOC films was much lower than those of a LC cell aligned on polyimide layers or other inorganic films. They found that LC molecules align vertically on ion beam treated SiOC film when the roughness of the electrostatic force microscopy (EFM) data is high on the SiOC film surface, while they align homogeneously when the roughness of the EFM data is low.

Son, Phil Kook; Park, Jeung Hun; Kim, Jae Chang; Yoon, Tae-Hoon; Rho, Soon Joon; Jeon, Back Kyun; Shin, Sung Tae; Kim, Jang Sub; Lim, Soon Kwon [School of Electrical Engineering, Pusan National University, Busan 609-735 (Korea, Republic of); LC/OLED Research Team, LCD R and D Center, LCD Business, Samsung Electronics Co. Ltd., Yongin, Gyeonggi-Do 449-711 (Korea, Republic of); Process Development Team, LCD R and D Center, LCD Business, Samsung Electronics Co. Ltd., Yongin, Gyeonggi-Do 449-711 (Korea, Republic of)



In search of ionic liquids incorporating azolate anions.  


Twenty-eight novel salts with tetramethyl-, tetraethyl-, and tetrabutylammonium and 1-butyl-3-methylimidazolium cations paired with 3,5-dinitro-1,2,4-triazolate, 4-nitro-1,2,3-triazolate, 2,4-dinitroimidazolate, 4,5-dinitroimidazolate, 4,5-dicyanoimidazolate, 4-nitroimidazolate, and tetrazolate anions have been prepared and characterized by using differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), and single-crystal X-ray crystallography. The effects of cation and anion type and structure on the physicochemical properties of the resulting salts, including several ionic liquids, have been examined and discussed. Ionic liquids (defined as having m.p.<100 degrees C) were obtained with all combinations of the 1-butyl-3-methylimidazolium cation ([C(4)mim](+)) and the heterocyclic azolate anions studied, and with several combinations of tetraethyl or tetrabutylammonium cations and the azolate anions. The [C(4)mim](+) azolates were liquid at room temperature exhibiting large liquid ranges and forming glasses on cooling with glass-transition temperatures in the range of -53 to -82 degrees C (except for the 3,5-dinitro-1,2,4-triazolate salt with m.p. 33 degrees C). Six crystal structures of the corresponding tetraalkylammonium salts were determined and the effects of changes to the cations and anions on the packing of the structure have been investigated. PMID:16586524

Katritzky, Alan R; Singh, Shailendra; Kirichenko, Kostyantyn; Smiglak, Marcin; Holbrey, John D; Reichert, W Matthew; Spear, Scott K; Rogers, Robin D



Regional electrophilic and nucleophilic Fukui functions efficiently highlight the Lewis acidic/basic regions in ionic liquids.  


The origin of catalysis and selectivity induced by room temperature ionic liquids in several organic reactions has putatively been associated with the concept of cation effect (hydrogen bond donor ability of the ionic liquids) or anion effect (hydrogen bond accepting ability of the ionic liquids). We show that there may be cases where this a priori classification may not be correctly assigned. Cations may concentrate both Lewis acidity and basicity functions in one fragment of the ionic liquid: an effect we tentatively call bifunctional distribution of the molecular Lewis acidity/basicity. Bifunctionality on the cation is however anion dependent through electronic polarization effects. The molecular distribution of the Lewis acidity/basicity may simply be assessed by evaluating the regional Fukui function within a reference ion pair structure. The model is tested for a set of nine ionic liquids based on the 1-butyl-3-methylimidazolium cation commonly used as solvent to run organic reactions. PMID:24617616

Cerda-Monje, Andrea; Ormazábal-Toledo, Rodrigo; Cárdenas, Carlos; Fuentealba, Patricio; Contreras, Renato



Phosphonium salt ionic liquids in organic synthesis  

Microsoft Academic Search

A survey of substitution reactions conducted in a phosphonium bistriflimide ionic liquid is presented. The results demonstrate high selectivity favoring substitution over typically competitive elimination and solvolytic processes even when challenging secondary and tertiary electrophiles are employed. The first reports of Kornblum substitution reactions in an ionic liquid are described that proceed with very high chemoselectivity in favor of nitro

Sreedhar Cheekoori



Ionic liquid-in-oil microemulsions.  


Phase stability and small-angle neutron scattering (SANS) data show that surfactant-stabilized nanodomains of a typical ionic liquid (1-butyl-3-methylimidazolium tetrafluoroborate [bmim][BF4]) may be dispersed by the nonionic surfactant Triton-X100 in cyclohexane. Analyses of these SANS data are consistent with the formation of ionic liquid-in-oil microemulsion droplets. PMID:15898765

Eastoe, Julian; Gold, Sarah; Rogers, Sarah E; Paul, Alison; Welton, Tom; Heenan, Richard K; Grillo, Isabelle



Crosslinked polymer gel electrolytes based on polyethylene glycol methacrylate and ionic liquid for lithium battery applications  

SciTech Connect

Gel polymer electrolytes were synthesized by copolymerization polyethylene glycol methyl ether methacrylate with polyethylene glycol dimethacrylate in the presence of a room temperature ionic liquid, methylpropylpyrrolidinium bis(trifluoromethanesulfonyl)imide (MPPY TFSI). The physical properties of gel polymer electrolytes were characterized by thermal analysis, impedance spectroscopy, and electrochemical tests. The ionic conductivities of the gel polymer electrolytes increased linearly with the amount of MPPY TFSI and were mainly attributed to the increased ion mobility as evidenced by the decreased glass transition temperatures. Li||LiFePO4 cells were assembled using the gel polymer electrolytes containing 80 wt% MPPY TFSI via an in situ polymerization method. A reversible cell capacity of 90 mAh g 1 was maintained under the current density of C/10 at room temperature, which was increased to 130 mAh g 1 by using a thinner membrane and cycling at 50 C.

Liao, Chen [ORNL; Sun, Xiao-Guang [ORNL; Dai, Sheng [ORNL



Vibrational photon echoes in a liquid and glass: Room temperature to 10 K A. Tokmakoff, D. Zimdars, B. Sauter, R. S. Francis, A. S. Kwok, and M. D. Fayer  

E-print Network

Vibrational photon echoes in a liquid and glass: Room temperature to 10 K A. Tokmakoff, D. Zimdars little is known about the temperature- dependent dynamics of molecular vibrations in liquids and glasses. This is the situation for electronic transitions in low temperature glasses and crystals, where the structure evolves

Fayer, Michael D.


Actinide chemistry in ionic liquids.  


This Forum Article provides an overview of the reported studies on the actinide chemistry in ionic liquids (ILs) with a particular focus on several fundamental chemical aspects: (i) complex formation, (ii) electrochemistry, and (iii) extraction behavior. The majority of investigations have been dedicated to uranium, especially for the 6+ oxidation state (UO2(2+)), because the chemistry of uranium in ordinary solvents has been well investigated and uranium is the most abundant element in the actual nuclear fuel cycles. Other actinides such as thorium, neptunium, plutonium, americium, and curiumm, although less studied, are also of importance in fully understanding the nuclear fuel engineering process and the safe geological disposal of radioactive wastes. PMID:22873132

Takao, Koichiro; Bell, Thomas James; Ikeda, Yasuhisa



Influence of an ionic liquid on the conduction characteristics of lithium niobophosphate glass  

NASA Astrophysics Data System (ADS)

A new solid electrolyte, mol% 1 [EMI]BF4-99(0.5Li2O-0.45P2O5-0.05Nb2O5), with room temperature ionic conductivity of 1.7 × 10-5 S/cm is reported for solid state device applications. Glass transition temperature of the hybrid system decreases by 20 K as compared to the pristine glass. Raman spectra in conjunction with thermal studies reveal that the addition of ionic liquid to the glass seems to increase the disorder in the glass leading to enhanced conductivity.

Dabas, Prashant; Hariharan, K.



Double-Line Hammett Relationship Revealed through Precise Acidity Measurement of Benzenethiols in Neat Ionic Media: A Typical "Ionic Liquid Effect"?  


Equilibrium acidities (pKa) of 14 aromatic thiols in four pure room temperature ionic liquids (RTILs) were precisely determined and the corresponding acidity scales were established for the first time. Regression analyses show a distinct double-line Hammett relationship with similar slopes and excellent linearity (R(2) of 0.996-0.999) in all four ILs. This could be rationalized by a resonance enhanced effect of the IL cation to solvate the para substituent of feasible electronic structure (CSAR effect), revealing a typical and rarely seen "ionic liquid effect". PMID:25314125

Wang, Zhen; Ji, Pengju; Li, Xin; Cheng, Jin-Pei



Liquid-liquid equilibrium of cholinium-derived bistriflimide ionic liquids with water and octanol.  


The liquid-liquid equilibria of mixtures of cholinum-based ionic liquids (N-alkyl-N,N-dimethylhydroxyethylammonium bis(trifluoromethane)sulfonylimide, [N(11n2OH)][Ntf(2)], n = 1, 2, 3, 4, and 5) plus water or 1-octanol were investigated at atmospheric pressure over the entire composition range. The experiments were conducted between 265 and 385 K using the cloud-point method. The systems exhibit phase diagrams consistent with the existence of upper critical solution temperatures. The solubility of [N(1 1 n 2OH)][Ntf(2)] in water is lower for cations with longer alkyl side chains (larger n values). The corresponding trend in the octanol mixtures is reversed. The ([N(1 1 1 2OH)][Ntf(2)] + water + octanol) ternary system shows triple liquid-liquid immiscibility at room temperature and atmospheric pressure. A combined analytic/synthetic method was used to estimate the corresponding phase diagram under those conditions. Auxiliary molecular dynamics simulation data were used to interpret the experimental results at a molecular level. PMID:22770438

Costa, Anabela J L; Soromenho, Mário R C; Shimizu, Karina; Marrucho, Isabel M; Esperança, José M S S; Canongia Lopes, J N; Rebelo, Luís Paulo N



The average free volume model for the ionic and simple liquids  

E-print Network

In this work, the molar volume thermal expansion coefficient of 60 room temperature ionic liquids is compared with their van der Waals volume Vw. Regular correlation can be discerned between the two quantities. An average free volume model, that considers the particles as hard core with attractive force, is proposed to explain the correlation in this study. Some typical one atom liquids (molten metals and liquid noble gases) are introduced to verify this hypothesis. Good agreement between the theory prediction and experimental data can be obtained.

Yu, Yang



On the mechanism of radiation-induced polymerization of vinyl monomers in ionic liquid  

NASA Astrophysics Data System (ADS)

An attempt was made to investigate the mechanism controlling the radiation-induced polymerization of vinyl monomers in room temperature ionic liquids. For that purpose, copolymerization of styrene (St) and methyl methacrylate (MMA) was initiated by 60Co gamma radiation in a moisture-stable ionic liquid, [choline chloride][ZnCl 2], and its mixture with THF (4:1 v/v). By analyzing the product composition with FTIR for a series of poly(St-co-MMA) samples, it was found that the mole fraction of St in the copolymer is linearly proportional to the mole fraction of St in the feed. Therefore, radiation polymerization in ionic liquid and its mixture with organic solvent is suggested to be a radical propagating process.

Liu, Yaodong; Wu, Guozhong



Ionic liquids for rechargeable lithium batteries  

SciTech Connect

We have investigated possible anticipated advantages of ionic-liquid electrolytes for use in lithium-ion batteries. Thermal stabilities and phase behavior were studied by thermal gravimetric analysis and differential scanning calorimetry. The ionic liquids studied include various imidazoliumTFSI systems, pyrrolidiniumTFSI, BMIMPF{sub 6}, BMIMBF{sub 4}, and BMIMTf. Thermal stabilities were measured for neat ionic liquids and for BMIMBF{sub 4}-LiBF{sub 4}, BMIMTf-LiTf, BMIMTFSI-LiTFSI mixtures. Conductivities have been measured for various ionic-liquid lithium-salt systems. We show the development of interfacial impedance in a Li|BMIMBF{sub 4} + LiBF{sub 4}|Li cell and we report results from cycling experiments for a Li|BMIMBF{sub 4} + 1 mol/kg LIBF{sub 4}|C cell. The interfacial resistance increases with time and the ionic liquid reacts with the lithium electrode. As expected, imidazolium-based ionic liquids react with lithium electrodes. We seek new ionic liquids that have better chemical stabilities.

Salminen, Justin; Papaiconomou, Nicolas; Kerr, John; Prausnitz,John; Newman, John



Ionic liquids for energy, materials, and medicine.  


As highlighted by the recent ChemComm web themed issue on ionic liquids, this field continues to develop beyond the concept of interesting new solvents for application in the greening of the chemical industry. Here some current research trends in the field will be discussed which show that ionic liquids research is still aimed squarely at solving major societal issues by taking advantage of new fundamental understanding of the nature of these salts in their low temperature liquid state. This article discusses current research trends in applications of ionic liquids to energy, materials, and medicines to provide some insight into the directions, motivations, challenges, and successes being achieved with ionic liquids today. PMID:24830849

Smiglak, M; Pringle, J M; Lu, X; Han, L; Zhang, S; Gao, H; MacFarlane, D R; Rogers, R D



Application of ionic liquids in actinide and fission product separations: progress and prospects.  

SciTech Connect

Ionic liquids (ILs), particularly those that are liquid at room temperature, have attracted intense interest as alternatives to conventional organic solvents in a host of synthetic, catalytic, and electrochemical applications. Recently, growing attention has been devoted to their use in separations, typically as replacements for the organic diluents employed in traditional liquid-liquid extraction or membrane-based separations of organic solutes or metal ions. Although studies of the extraction of metal ions into various ILs indicate that these solvents frequently provide extraction efficiencies far greater than those obtained with conventional solvents, other work suggests that they suffer from various drawbacks that could limit their utility as extraction solvents. In this chapter, we examine the viability of ionic liquids as the basis for extraction systems for the separation of actinides and fission products from acidic media and consider approaches by which their limitations may be overcome.

Stepinski, D. C.; Young, B. A.; Jensen, M. P.; Rickert, P. G.; Dzielawa, J. A.; Dilger, A. A.; Rausch, D. J.; Dietz, M. L.; Chemistry



Cooperative effect of ionic liquid solvents in microfluidic devices for fabricating monodisperse metal nanoparticles  

NASA Astrophysics Data System (ADS)

Room temperature ionic liquids have been receiving attention as alternatives to traditional organic solvents. In particular, 1,3-dialkylimidazolium ionic liquids are attractive because their properties are easily tailored by altering the counteranion and type of alkyl chains on the imidazolium ring. Ionic liquids are finding use as dual-function solvents and stabilizing agents for nanoparticles. They are able to solvate a wide variety of species and are thought to consist of polar and non-polar domains of hydrogen bonded networks, which may be able to stabilize and even template nanoparticle growth. They have several other properties (e.g., nonflammability, nonvolatility, recyclability) that potentially make them more environmentally sound compared to some traditional organic solvents. We have developed different microfluidic architectures for the synthesis of gold and silver nanoparticles in ionic liquid flows. The large surface area-to-volume ratio within microscale channels allows for improved heat and mass transport and more homogeneous reaction conditions, leading to monodisperse nanoparticle products. Additionally, microfluidic syntheses allow for finer control over reaction parameters compared to traditional batch reactions. Herein, we examined the combined beneficial effects of ionic liquid flows and different microfluidic systems to prepare gold and silver nanoparticles that are more monodisperse than those produced in analogous batch reactions. The compatibility of ionic liquids with inexpensive polydimethylsiloxane microfluidic devices makes it a unique system for the reproducible synthesis of high-quality nanoparticles.

Lazarus, Laura L.


[BPy]HSO4 Acidic Ionic Liquid as a Novel, Efficient, and Environmentally Benign Catalyst for Synthesis of 1,5?Benzodiazepines under Mild Conditions  

Microsoft Academic Search

A novel and simple ionic liquid methodology for the synthesis of 1,5?benzodiazepines is described. 1?Butylpyridinium hydrogen sulphate ([BPy]HSO4), an acidic room?temperature ionic liquid, as a novel and efficient catalyst, was synthesized and used in the preparation of a series of 1,5?benzodiazepine derivatives by the reaction of o?phenylenediamine with chalcones under mild conditions. This method is easy, efficient, environmentally friendly, economical,

Yuying Du; Fuli Tian; Wenzhi Zhao



Air-liquid interface of ionic liquid-water binary system studied by surface tension measurement and sum-frequency generation spectroscopy  

Microsoft Academic Search

Surface of room-temperature ionic liquid (RIL)+water mixture is investigated using surface tension measurement and surface sum- frequency generation (SFG) vibrational spectroscopy. Results indicate the liquid surface is mostly covered by the cations at a very low bulk concentration (less than 0.02 bulk mole fraction). Increase of surface tension from 0.016 up to ˜0.05 mole fraction suggested that the anions start

Jaeho Sung; Takashi Iwahashi



Unraveling the heterogeneity in N butyl-N-methylpiperidinium trifluromethanesulfonimide ionic liquid by 1D and 2D NMR spectroscopy  

NASA Astrophysics Data System (ADS)

Room temperature ionic liquids are one of the most exciting classes of materials in the last decade. In particular piperidinium (PIP) cation based ionic liquid (IL) (such as PIP14NTf2) have found application in electrochemistry/batteries. In this Letter, 2D NMR (NOESY and HOESY) is employed for studying the interactions present between cations and anions. HOESY spectrum shows that fluorine of NTf2 unusually interacts with all proton of the cation (PIP14). Combined HOESY and NOESY indicate that NTf2 anion is distributed heterogeneously in liquid. Existence of micro heterogeneity in this important class of IL is proposed.

Tripathi, Neha; Saha, Satyen



Use of Ionic Liquids in Rod-Coil Block Copolyimides for Improved Lithium Ion Conduction  

NASA Technical Reports Server (NTRS)

Solvent-free, solid polymer electrolytes (SPE) have the potential to improve safety, increase design flexibility and enhance performance of rechargeable lithium batteries. Solution based electrolytes are flammable and typically incompatible with lithium metal anodes, limiting energy density. We have previously demonstrated use of polyimide rod coil block copolymers doped with lithium salts as electrolytes for lithium polymer batteries. The polyimide rod blocks provide dimensional stability while the polyethylene oxide (PEO) coil portions conduct ions. Phase separation of the rods and coils in these highly branched polymers provide channels with an order of magnitude improvement in lithium conduction over polyethylene oxide itself at room temperature. In addition, the polymers have been demonstrated in coin cells to be compatible with lithium metal. For practical use at room temperature and below, however, at least an order of magnitude improvement in ion conduction is still required. The addition of nonvolatile, room temperature ionic liquids has been shown to improve the ionic conductivity of high molecular weight PEO. Herein we describe use of these molten salts to improve ionic conductivity in the rod-coil block copolymers.

Meador, Mary Ann B.; Tigelaar, Dean M.; Chapin, Kara; Bennett, William R.



Ionic liquid polyoxometalates as light emitting materials  

SciTech Connect

The low melting point, negligible vapor pressure, good solubility, and thermal and chemical stability make ionic liquids useful materials for a wide variety of applications. Polyoxometalates are early transition metal oxygen clusters that can be synthesized in many different sizes and with a variety of heterometals. The most attractive feature of POMs is that their physical properties, in particular electrical, magnetic, and optical properties, can be easily modified following known procedures. It has been shown that POMs can exhibit cooperative properties, as superconductivity and energy transfer. POM ionic liquids can be obtained by selecting the appropliate cation. Different alkyl ammonium and alkyl phosphonium salts are being used to produce new POM ionic liquids together with organic or inorganic luminescent centers to design light emitting materials. Ammonium and phosphonium cations with activated, polymerizable groups are being used to further polymerize the ionic liquid into transparent, solid materials with high metal density.

Ortiz-acosta, Denisse [Los Alamos National Laboratory; Del Sesto, Rico E [Los Alamos National Laboratory; Scott, Brian [Los Alamos National Laboratory; Bennett, Bryan L [Los Alamos National Laboratory; Purdy, Geraldine M [Los Alamos National Laboratory; Muenchausen, Ross E [Los Alamos National Laboratory; Mc Kigney, Edward [Los Alamos National Laboratory; Gilbertson, Robert [Los Alamos National Laboratory



Group transfer polymerisation in hydrophobic ionic liquids.  


For the first time, group transfer polymerisation of methyl methacrylate (MMA) has been successfully carried out at ambient temperatures in an ionic liquid to produce living polymers of improved polydispersity. PMID:15726174

Vijayaraghavan, Ranganathan; MacFarlane, Douglas R



Room temperature polyesterification  

SciTech Connect

A new room temperature polymerization method has been developed for the synthesis of high molecular weight polyesters directly from carboxylic acids and phenols. The solution polymerization reaction proceeds under mild conditions, near neutral pH, and also avoids the use of preactivated acid derivatives for esterification. The reaction is useful in the preparation of isoregic ordered chains with translational polar symmetry and also in the polymerization of functionalized or chiral monomers. The conditions required for polymerization in the carbodiimide-based reaction included catalysis by the 1:1 molecular complex formed by 4-(dimethylamino)pyridine and p-toluenesulfonic acid. These conditions were established through studies on a model system involving esterification of p-toluic acid and p-cresol. Self-condensation of several hydroxy acid monomers by this reaction has produced routinely good yields of polyesters with molecular weights greater than 15,000. It is believed that the high extents of reaction required for significant degrees of polymerization result from suppression of the side reaction leading to N-acylurea. The utility of this reaction in the formation of polar chains from sensitive monomers is demonstrated hereby the polycondensation of a chiral hydroxy acid.

Moore, J.S.; Stupp, S.I. (Univ. of Illinois, Urbana, IL (United States). Dept. of Materials Science and Engineering)



Vibrational spectroscopic study of ionic liquids: Comparison between monocationic and dicationic imidazolium ionic liquids  

NASA Astrophysics Data System (ADS)

In this study, we synthesised a dicationic ionic liquids labeled bis-methyl imidazolium methylidene bis (trifluoromethanesulfonyl) imide ([M(CH2)IM2+][2NTf2-]). The structure was identified by NMR. In order to characterise this ionic liquid, vibrational spectroscopy studies were performed by FTIR/ATR and FT-Raman spectroscopies. A comparative study was introduced by FTIR/ATR and FT-Raman spectroscopies, between our synthesised dicationic ionic liquid and a monocationic ionic liquid ([EMIM+][NTf2-]), where the anion and the cation are similar.

Moumene, Taqiyeddine; Belarbi, El Habib; Haddad, Boumediene; Villemin, Didier; Abbas, Ouissam; Khelifa, Brahim; Bresson, Serge



Superbase-derived protic ionic liquids  


Protic ionic liquids having a composition of formula (A.sup.-)(BH.sup.+) wherein A.sup.- is a conjugate base of an acid HA, and BH.sup.+ is a conjugate acid of a superbase B. In particular embodiments, BH.sup.+ is selected from phosphazenium species and guanidinium species encompassed, respectively, by the general formulas: ##STR00001## The invention is also directed to films and membranes containing these protic ionic liquids, with particular application as proton exchange membranes for fuel cells.

Dai, Sheng; Luo, Huimin; Baker, Gary A.



Ionic liquid-based liquid-phase microextraction, a new sample enrichment procedure for liquid chromatography.  


Room temperature ionic liquids (RTILs) were used as extraction solvent in liquid-phase microextraction (LPME) coupled with liquid chromatography. Using 1-hexyl-3-methylimidazolium hexafluorophosphate ([C6MIM][PF6]) as extraction solvent, some parameters related to LPME of 4-nonylphenol (4-NP) and 4-tert-octylphenol (4-t-OP) were optimized. Although [C6MIM][PF6] can suspend a much larger volume of drop on the needle of the microsyringe than the conventional solvents such as 1-octanol and carbon tetrachloride, the method sensitivity was analyte dependent because of the different partition coefficients and the relatively large viscosity of [C6MIM][PF6]. The proposed procedure has a detection limit and enrichment factor of 0.3 microg l(-1) and 163 for 4-NP, and 0.7 microg l(-1) and 130 for 4-t-OP, respectively. Aqueous samples including tap water, river water, and effluent from sewage treatment plant were analyzed by the proposed method and the recoveries at 10 microg l(-1) spiked level were in the range of 90-113%. PMID:14763740

Liu, Jing-fu; Chi, Yu-guang; Jiang, Gui-bin; Tai, Chao; Peng, Jin-feng; Hu, Jing-Tian



The distillation and volatility of ionic liquids  

NASA Astrophysics Data System (ADS)

It is widely believed that a defining characteristic of ionic liquids (or low-temperature molten salts) is that they exert no measurable vapour pressure, and hence cannot be distilled. Here we demonstrate that this is unfounded, and that many ionic liquids can be distilled at low pressure without decomposition. Ionic liquids represent matter solely composed of ions, and so are perceived as non-volatile substances. During the last decade, interest in the field of ionic liquids has burgeoned, producing a wealth of intellectual and technological challenges and opportunities for the production of new chemical and extractive processes, fuel cells and batteries, and new composite materials. Much of this potential is underpinned by their presumed involatility. This characteristic, however, can severely restrict the attainability of high purity levels for ionic liquids (when they contain poorly volatile components) in recycling schemes, as well as excluding their use in gas-phase processes. We anticipate that our demonstration that some selected families of commonly used aprotic ionic liquids can be distilled at 200-300°C and low pressure, with concomitant recovery of significant amounts of pure substance, will permit these currently excluded applications to be realized.

Earle, Martyn J.; Esperança, José M. S. S.; Gilea, Manuela A.; Canongia Lopes, José N.; Rebelo, Luís P. N.; Magee, Joseph W.; Seddon, Kenneth R.; Widegren, Jason A.



Phase behaviour and dynamics in primitive models of molecular ionic liquids  

E-print Network

The phase behaviour and dynamics of molecular ionic liquids are studied using primitive models and extensive computer simulations. The models account for size disparity between cation and anion, charge location on the cation, and cation-shape anisotropy, which are all prominent features of important materials such as room-temperature ionic liquids. The vapour-liquid phase diagrams are determined using high-precision Monte Carlo simulations, setting the scene for in-depth studies of ion dynamics in the liquid state. Molecular dynamics simulations are used to explore the structure, single-particle translational and rotational autocorrelation functions, cation orientational autocorrelations, self diffusion, viscosity, and frequency-dependent conductivity. The results reveal some of the molecular-scale mechanisms for charge transport, involving molecular translation, rotation, and association.

G. C. Ganzenmüller; P. J. Camp



Components of Dielectric Constants of Ionic Liquids  

NASA Astrophysics Data System (ADS)

In this study ab initio-based methods were used to calculate electronic polarizability and dipole moment of ions comprising ionic liquids [1]. The test set consisted of a number of anions and cations routinely used in the ionic liquid field. As expected, in the first approximation electronic polarizability volume turned out to be proportional to the ion volume, also calculated by means of ab initio theory. For ionic liquid ions this means that their electronic polarizabilities are at least an order of magnitude larger than those of traditional molecular solvents like water and DMSO. On this basis it may seem surprising that most of ionic liquids actually possess modest dielectric constants, falling the narrow range between 10 and 15. The lower than first expected dielectric constants of ionic liquids has been explored in this work via explicit calculations of the electronic and orientation polarization contributions to the dielectric constant using the Clausius-Mossotti equation and the Onsager theory for polar dielectric materials. We determined that the electronic polarization contribution to the dielectric constant was rather small (between 1.9 and 2.2) and comparable to that of traditional molecular solvents. These findings were explained by the interplay between two quantities, increasing electronic polarizability of ions and decreasing number of ions present in the unit volume; although electronic polarizability is usually relatively large for ionic liquid ions, due to their size there are fewer ions present per unit volume (by a factor of 10 compared to traditional molecular solvents). For ionic liquids consisting of ions with zero (e.g. BF4) or negligible (e.g. NTf2) dipole moments the calculated orientation polarization does not contribute enough to account for the whole of the measured values of the dielectric constants. We suggest that in ionic liquids an additional type of polarization, ``ionic polarization'', originating from small movements of the centre of the charge on the ions might be present. According to our estimations, this ionic polarization contribution to the dielectric constant could be rather significant (between 8 and 10 for some ionic liquids). In collaboration with Douglas R. MacFarlane, School of Chemistry, Monash University. [4pt] [1] E. I. Izgorodina, M. Forsyth and D. R. MacFarlane, Phys. Chem. Chem. Phys., 11, 2452, 2009.

Izgorodina, Ekaterina I.



Single particle dynamics in ionic liquids of 1-alkyl-3-methylimidazolium cations  

NASA Astrophysics Data System (ADS)

Ionic dynamics in room temperature molten salts (ionic liquids) containing 1-alkyl-3-methylimidazolium cations is investigated by molecular-dynamics simulations. Calculations were performed with united atom models, which were used in a previous detailed study of the equilibrium structure of ionic liquids [S. M. Urahata and M. C. C. Ribeiro, J. Chem. Phys. 120, 1855 (2004)]. The models were used in a systematic study of the dependency of several single particle time correlation functions on anion size (F-, Cl-, Br-, and PF6-) and alkyl chain length (1-methyl-, 1-ethyl-, 1-butyl-, and 1-octyl-). Despite of large mass and size of imidazolium cations, they exhibit larger mean-square displacement than anions. A further detailed picture of ionic motions is obtained by using appropriate projections of displacements along the plane or perpendicular to the plane of the imidazolium ring. A clear anisotropy in ionic displacement is revealed, the motion on the ring plane and almost perpendicular to the 1-alkyl chain being the less hindered one. Similar projections were performed on velocity correlation functions, whose spectra were used to relate short time ionic rattling with the corresponding long time diffusive regime. Time correlation functions of cation reorientation and dihedral angles of the alkyl chains are discussed, the latter decaying much faster than the former. A comparative physical picture of time scales for distinct dynamical processes in ionic liquids is provided.

Urahata, Sérgio M.; Ribeiro, Mauro C. C.



Room-temperature stabilization of nanoscale superionic Ag2Se  

NASA Astrophysics Data System (ADS)

Superionic materials are multi-component solids in which one sub-lattice exhibits high ionic conductivity within a fixed crystalline structure. This is typically associated with a structural phase transition occurring significantly above room temperature. Here, through combined temperature-resolved x-ray diffraction and differential scanning calorimetry, we map out the nanoscale size-dependence of the Ag2Se tetragonal to superionic phase transition temperature and determine the threshold size for room-temperature stabilization of superionic Ag2Se. For the first time, clear experimental evidence for such stabilization of the highly ionic conducting phase at room temperature is obtained in ?2 nm diameter spheres, which corresponds to a >100 °C suppression of the bulk phase transition temperature. This may enable technological applications of Ag2Se in devices where high ionic conductivity at room temperature is required.

Hu, T.; Wittenberg, J. S.; Lindenberg, A. M.



Room-temperature stabilization of nanoscale superionic Ag2Se.  


Superionic materials are multi-component solids in which one sub-lattice exhibits high ionic conductivity within a fixed crystalline structure. This is typically associated with a structural phase transition occurring significantly above room temperature. Here, through combined temperature-resolved x-ray diffraction and differential scanning calorimetry, we map out the nanoscale size-dependence of the Ag2Se tetragonal to superionic phase transition temperature and determine the threshold size for room-temperature stabilization of superionic Ag2Se. For the first time, clear experimental evidence for such stabilization of the highly ionic conducting phase at room temperature is obtained in ?2 nm diameter spheres, which corresponds to a >100 °C suppression of the bulk phase transition temperature. This may enable technological applications of Ag2Se in devices where high ionic conductivity at room temperature is required. PMID:25249347

Hu, T; Wittenberg, J S; Lindenberg, A M



Ionic liquid based electrolytes for sodium-ion batteries: Na+ solvation and ionic conductivity  

NASA Astrophysics Data System (ADS)

Ionic liquid (IL) based sodium-ion (Na+) battery electrolytes obtained by mixing imidazolium-TFSI ILs (EMIm-TFSI and BMIm-TFSI) with the corresponding sodium salt (NaTFSI) have been investigated using a wide range of characterization techniques: dielectric spectroscopy, differential scanning calorimetry, densitometry, viscometry, and Raman spectroscopy. The sodium ion conducting electrolytes exhibit excellent ionic conductivities, up to 5.5 mS cm-1 at room temperature, and a useful thermal window of -86 °C to 150 °C. In more detail, Raman data analysis supported by DFT calculations on Na+-TFSI complexes, allow us to determine the sodium ion solvation and charge carrier nature as a function of salt concentration. The results are compared to data for the corresponding Li systems and while such electrolytes essentially form [Li(TFSI)2]- as the main Li+ carrier, the sodium systems seem to dominantly form [Na(TFSI)3]2- complexes. The effects on conductivity and viscosity and the consequences for sodium-ion battery implementation are discussed.

Monti, Damien; Jónsson, Erlendur; Palacín, M. Rosa; Johansson, Patrik



Morphology and Ionic Conductivity of Block Copolymer--Ionic Liquid Systems  

Microsoft Academic Search

Block copolymer--ionic liquid systems are of interest for ion exchange membranes due to the ionic conductivity and thermal stability of the ionic liquid combined with the thermal stability and morphological control arising from a structural component in a block copolymer. It is anticipated that the morphology and connectivity of the resulting structural and ionic liquid-containing nanodomains will affect conduction properties.

M. L. Hoarfrost; J. M. Virgili; J. B. Kerr; R. A. Segalman



"Bicontinuous cubic" liquid crystalline materials from discotic molecules: a special effect of paraffinic side chains with ionic liquid pendants.  


Triphenylene (TP) derivatives bearing appropriate paraffinic side chains with imidazolium ion-based ionic liquid (IL) pendants were unveiled to display a phase diagram with liquid crystalline (LC) mesophases of bicontinuous cubic (Cub(bi)) and hexagonal columnar (Col(h)) geometries. While their phase transition behaviors are highly dependent on the length of the side chains and the size of the ionic liquid pendants, TPs with hexadecyl side chains exclusively form a Cub(bi) LC assembly over an extremely wide temperature range of approximately 200 degrees C from room temperature when the anions of the IL pendants are relatively small. Wide-angle X-ray diffraction analysis suggested that the Cub(bi) LC mesophase contains pi-stacked columnar TP arrays with a plane-to-plane separation of approximately 3.5 A. Consistently, upon laser flash photolysis, it showed a transient microwave conductivity comparable to that of a Col(h) LC reference. PMID:19995070

Alam, Md Akhtarul; Motoyanagi, Jin; Yamamoto, Yohei; Fukushima, Takanori; Kim, Jungeun; Kato, Kenichi; Takata, Masaki; Saeki, Akinori; Seki, Shu; Tagawa, Seiichi; Aida, Takuzo



Electrorecovery of actinides at room temperature  

SciTech Connect

There are a large number of purification and processing operations involving actinide species that rely on high-temperature molten salts as the solvent medium. One such application is the electrorefining of impure actinide metals to provide high purity material for subsequent applications. There are some drawbacks to the electrodeposition of actinides in molten salts including relatively low yields, lack of accurate potential control, maintaining efficiency in a highly corrosive environment, and failed runs. With these issues in mind we have been investigating the electrodeposition of actinide metals, mainly uranium, from room temperature ionic liquids (RTILs) and relatively high-boiling organic solvents. The RTILs we have focused on are comprised of 1,3-dialkylimidazolium or quaternary ammonium cations and mainly the {sup -}N(SO{sub 2}CF{sub 3}){sub 2} anion [bis(trif1uoromethylsulfonyl)imide {equivalent_to} {sup -}NTf{sub 2}]. These materials represent a class of solvents that possess great potential for use in applications employing electrochemical procedures. In order to ascertain the feasibility of using RTILs for bulk electrodeposition of actinide metals our research team has been exploring the electron transfer behavior of simple coordination complexes of uranium dissolved in the RTIL solutions. More recently we have begun some fundamental electrochemical studies on the behavior of uranium and plutonium complexes in the organic solvents N-methylpyrrolidone (NMP) and dimethylsulfoxide (DMSO). Our most recent results concerning electrodeposition will be presented in this account. The electrochemical behavior of U(IV) and U(III) species in RTILs and the relatively low vapor pressure solvents NMP and DMSO is described. These studies have been ongoing in our laboratory to uncover conditions that will lead to the successful bulk electrodeposition of actinide metals at a working electrode surface at room temperature or slightly elevated temperatures. The RTILs we have focused on thus far are based on 1,3-dialkylimidazolium or quaternary ammonium cations and {sup -}N(SO{sub 2}CF{sub 3}){sub 2} anions. Our results from XPS studies of e1ectrooxidized uranium metal surfaces indicate that uranium metal reacts with the anion from the RTIL, most likely through an initial f1uoride abstraction, forming decomposition products that inhibit the bulk electrodeposition of uranium metal. Similar results were found when the organic solvents were used with TBA[B(C{sub 6}F{sub 5}){sub 4}] as the supporting electrolyte, although the voltammetric data of uranium ions in these solutions is more encouraging in relation to electrodeposition of uranium metal. Preliminary results on the voltammetric behavior and bulk electrodeposition of plutonium species are also presented.

Stoll, Michael E [Los Alamos National Laboratory; Oldham, Warren J [Los Alamos National Laboratory; Costa, David A [Los Alamos National Laboratory



Electrolytes based on alkoxysilyl-functionalized ionic liquids: viscoelastic properties and conductivity.  


Ionic liquids can be successfully used as electrolytes in electrochemical devices when they are in their quasi-solid state. Among several methods of solidification, a sol-gel process was chosen and a set of alkoxysilyl-functionalized iodide imidazolium-based ionic liquids were synthesized. The electrolytes were prepared by mixing these ionic liquids with a non-polymerisable ionic liquid (1-methyl-3-propylimidazolium iodide (MPIm(+)I(-))). Iodine was dissolved in an electrolyte matrix in order to form an I3(-)/I(-) redox couple. The change of the structure from sol to gel was followed by rheological tests in order to show the effect of different rheological parameters on the gelation process. The solvolysis with glacial acetic acid and condensation were followed by rheological experiments on the samples taken from a batch, and in situ on the rheometer. The formed three-dimensional sol-gel networks of various alkoxysilyl-functionalized ionic liquids differed in their microstructures and viscoelastic properties that were correlated with conductivity. The results show that the conductivity of approximately 10(-3) S cm(-1) at room temperature was achieved for the gels with relatively high values of elastic modulus and noticeable viscous contribution. It is shown that not only the viscosity but also the viscoelastic behavior and especially the relationship between viscous and elastic moduli (phase shift) together with the time of gelation are essential for the high conductivity of electrolytes. PMID:24955729

Slemenik Perše, L; Colovi?, M; Hajzeri, M; Orel, B; Surca Vuk, A



Ionic Liquids for Utilization of Waste Heat from Distributed Power Generation Systems  

SciTech Connect

The objective of this research project was the development of ionic liquids to capture and utilize waste heat from distributed power generation systems. Ionic Liquids (ILs) are organic salts that are liquid at room temperature and they have the potential to make fundamental and far-reaching changes in the way we use energy. In particular, the focus of this project was fundamental research on the potential use of IL/CO2 mixtures in absorption-refrigeration systems. Such systems can provide cooling by utilizing waste heat from various sources, including distributed power generation. The basic objectives of the research were to design and synthesize ILs appropriate for the task, to measure and model thermophysical properties and phase behavior of ILs and IL/CO2 mixtures, and to model the performance of IL/CO2 absorption-refrigeration systems.

Joan F. Brennecke; Mihir Sen; Edward J. Maginn; Samuel Paolucci; Mark A. Stadtherr; Peter T. Disser; Mike Zdyb



Electrodeposition of macroporous silver films from ionic liquids and assessment of these films in the electrocatalytic reduction of nitrate  

Microsoft Academic Search

Macroporous silver films, ordered or fragmented, were fabricated by electrodeposition of silver into the interstitial spaces of templates formed by polystyrene (PS) latex spheres that had been self-assembled onto bare indium tin oxide (ITO) electrodes or onto gold-coated ITO (ITO\\/Au) electrodes (in which the electrode had been coated by gold sputtering deposition) from two room-temperature ionic liquids (ILs): N-butyl-N-methylpyrrolidinium bis(trifluoromethanesulfonyl)imide

Ming-Chih Tsai; Ding-Xuan Zhuang; Po-Yu Chen



Ionic-liquid\\/NH 2-MWCNTs as a highly sensitive nano-composite for catalase direct electrochemistry  

Microsoft Academic Search

A nano-composite material consisting of amine functionalized multi-walled carbon nanotubes and a room temperature ionic-liquid (1-butyl-3-methylimidazolium tetrafluoroborate) was prepared and used to construct a novel catalase (Ct) based biosensor for the determination of hydrogen peroxide. The modified electrode exhibited a quasi-reversible cyclic voltammogram corresponding to the Fe(II)\\/Fe(III) redox couple in the heme prosthetic group of Ct with a formal potential

Parvaneh Rahimi; Hossain-Ali Rafiee-Pour; Hedayatollah Ghourchian; Parviz Norouzi; Mohammad Reza Ganjali



Surface Nanocrystallization of an Ionic Liquid  

SciTech Connect

Surface crystallization at the vapor-liquid interface of the ionic liquid (1-butyl-3-methylimidazolium hexafluorophosphate) is observed in synchrotron x-ray diffraction studies. Sharp Bragg reflections emerge in grazing-angle x-ray diffraction patterns 37 C above the bulk melting temperature, indicating the presence of a long-range ordered phase at the surface in coexistence with the bulk parent liquid. The unique structure of the vapor-liquid interface where butyl chains attached to the cations are expelled to the vapor side facilitates interionic electrostatic interactions that lead to the crystallization. Our results demonstrate the complexity of ionic-liquid structure with their tendency to spontaneously phase separate into nanodomains with finite correlation lengths in coexistence with the liquid phase. By virtue of interfacial boundary conditions, these nanodomains grow laterally to form quasi-two-dimensional crystals.

Jeon, Yoonnam; Vaknin, David; Bu, Wei; Sung, Jaeho; Ouchi, Yukio; Sung, Woongmo; Kim, Doseok (Iowa State); (Nagoya); (Sogang)



Physicochemical Properties of Imidazolium-derived Ionic Liquids with Different C-2 Substitutions  

SciTech Connect

Five room temperature ionic liquids based on C-2 substituted imidazolium cations and bis(trifluoromethanesulfonyl)imide (TFSI) anion were synthesized and their physicochemical properties: thermal property, density, viscosity, ionic conductivity, self-diffusion coefficients, and electrochemical stability were systematically investigated. The temperature dependence of both viscosity and ionic conductivities of these ionic liquids can be described by Vogel-Fulcher-Tamman (VFT) equation. Compared with the reference, 1-propyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide, the introduction of functional groups at the C-2 position generally increased the viscosity and lowered the ionic conductivity. The introduction of ether group ( CH2OCH2CH2CH2CH3) at the C-2 position not only enhanced the reduction stability of the ionic liquids but also exhibited the lowest solid electrolyte interfacial resistance (RSEI). On the contrary, the introduction of a cyano group ( CN) at the C-2 position not only decreased the reduction stability but also adversely increased the SEI resistance. The effect of the C-2 substitution on the reduction stability was explained by the change of the energy level of the lowest unoccupied molecular orbital. The self-diffusion coefficients (D) of each ion were measured by pulsed field gradient nuclear magnetic resonance (PFG-NMR). The lithium transference number (tLi) of 0.5 M LiTFSI/IL solutions calculated from the self-diffusion coefficients was in the range of 0.04 and 0.09.

Liao, Chen [ORNL; Shao, Nan [ORNL; Han, Kee Sung [ORNL; Sun, Xiao-Guang [ORNL; Jiang, Deen [ORNL; Hagaman, Edward {Ed} W [ORNL; Dai, Sheng [ORNL



Physicochemical properties of imidazolium-derived ionic liquids with different C-2 substitutions.  


Five room temperature ionic liquids based on C-2 substituted imidazolium cations and bis(trifluoromethanesulfonyl)imide (TFSI) anions were synthesized and their physicochemical properties: thermal property, density, viscosity, ionic conductivity, self-diffusion coefficients, and electrochemical stability, were systematically investigated. The temperature dependence of both viscosity and ionic conductivities of these ionic liquids can be described by the Vogel-Fulcher-Tamman (VFT) equation. Compared with the reference, 1-propyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide, the introduction of functional groups at the C-2 position generally increased the viscosity and lowered the ionic conductivity. The introduction of an ether group (-CH(2)OCH(2)CH(2)CH(2)CH(3)) at the C-2 position not only enhanced the reduction stability of the ionic liquids but also exhibited the lowest solid electrolyte interfacial resistance (R(SEI)). In contrast, the introduction of a cyano group (-CN) at the C-2 position not only decreased the reduction stability but also adversely increased the SEI resistance. The effect of the C-2 substitution on the reduction stability was explained by the change in the energy level of the lowest unoccupied molecular orbital. The self-diffusion coefficients (D) of each ion were measured by pulsed field gradient nuclear magnetic resonance (PFG-NMR). The lithium transference number (t(Li)) of 0.5 M LiTFSI/IL solutions calculated from the self-diffusion coefficients was in the range of 0.04 to 0.09. PMID:22068150

Liao, Chen; Shao, Nan; Han, Kee Sung; Sun, Xiao-Guang; Jiang, De-En; Hagaman, Edward W; Dai, Sheng



Modification and implications of changes in electrochemical responses encountered when undertaking deoxygenation in ionic liquids.  


Physicochemical changes and substantially modified electrochemical behavior have been reported when ionic liquids are degassed with nitrogen. In conventional experiments in aqueous and organic media, degassing with N(2) is commonly used to remove the electroactive dissolved oxygen. However, in hydrophilic ionic liquid media, degassing with N(2) removes not only the dissolved oxygen but also a significant amount of the adventitious water present. Given the low viscosity of water, this in turn leads to a dramatic change of the viscosity of the degassed ionic liquid and hence mass transport properties that influence voltammetric responses. In the widely used and relatively viscous room temperature ionic liquid, 1-n-butyl-3-methylimidazolium tetrafluoroborate (BMIMBF(4)) containing the redox probe tetracyanoquinodimethane (TCNQ) and 9% (v/v) deliberately added water, 1 h degassing with very dry N(2) under benchtop conditions results in a dramatic decrease of the TCNQ reduction current obtained under steady-state conditions at a 1 mum diameter microdisc electrode. This is reflected by a change of diffusion coefficient of TCNQ (D(TCNQ)) from 2.6 x 10(-7) to 4.6 x 10(-8) cm(2) s(-1). Karl Fischer titration measurements show that almost complete removal of the deliberately added 9% water is achieved by degassing under benchtop conditions. However, displacement of oxygen by nitrogen in the ionic liquid solution results in the decrease of electrochemical reduction current by 6%, implying that dissolved gases need not be inert with respect to solvent properties. Oxygen removal by placing the BMIMBF(4) ionic liquid in a nitrogen-filled glovebox or in a vacuum cell also simultaneously leads to removal of water and alteration of voltammetric data. This study highlights that (i) important physicochemical differences may arise upon addition or removal of a solute from viscous ionic liquids; (ii) degassing with dry nitrogen removes water as well as oxygen from ionic liquids, which may have implications on the viscosity and structure of the medium; (iii) particular caution must be exercised when deoxygenation is applied in ionic liquid media as part of the protocol used in electrochemical experiments to remove oxygen; (iv) gases such as oxygen, argon, and nitrogen dissolved in ionic liquids need not be innocent with respect to the properties of an ionic liquid. The use of vacuum based techniques to eliminate all volatile solutes, including water and oxygen, is advocated. PMID:20392069

Zhao, Chuan; Bond, Alan M; Compton, Richard G; O'Mahony, Aoife M; Rogers, Emma I



Enzyme activity in dialkyl phosphate ionic liquids  

SciTech Connect

The activity of four metagenomic enzymes and an enzyme cloned from the straw mushroom, Volvariellavolvacea were studied in the following ionic liquids, 1,3-dimethylimidazolium dimethyl phosphate, [mmim][dmp], 1-ethyl-3-methylimidazolium dimethyl phosphate, [emim][dmp], 1-ethyl-3-methylimidazolium diethyl phosphate, [emim][dep] and 1-ethyl-3-methylimidazolium acetate, [emim][OAc]. Activity was determined by analyzing the hydrolysis of para-nitrobenzene carbohydrate derivatives. In general, the enzymes were most active in the dimethyl phosphate ionic liquids, followed by acetate. Generally speaking, activity decreased sharply for concentrations of [emim][dep] above 10% v/v, while the other ionic liquids showed less impact on activity up to 20% v/v.

Thomas, M.F.; Dunn, J.; Li, L.-L.; Handley-Pendleton, J. M.; van der lelie, D.; Wishart, J. F.



Fluorescence Correlation Spectroscopy Evidence for Structural Heterogeneity in Ionic Liquids  

SciTech Connect

Self-aggregation in room temperature ionic liquids (RTILs) has been a subject of intense interest in recent years. In this work, we provide new experimental evidence for chain length-dependent self-aggregation in RTILs using fluorescence correlation spectroscopy (FCS). In studying a homologous series of N-alkyl-N-methylpyrrolidinium bis(trifluoromethylsulfonyl) imide, [CnMPy][Tf2N] RTILs of varying alkyl chain length (n = 3, 4, 6, 8, and 10), biphasic rhodamine 6G solute diffusion dynamics were observed; both the fast and slow diffusion coefficients decrease with increasing alkyl chain length, with the relative contribution from slower diffusion increasing for longer-chained [CnMPy][Tf2N]. We propose that the biphasic diffusion dynamics originate from self-aggregation of the nonpolar alkyl chains in the cationic [CnMPy]+. The presence of this local liquid structuring provides important insight into the behavior of RTILs relevant to their application in photovoltaics, fuel cells, and batteries.

Guo, Jianchang [ORNL; Baker, Gary A [ORNL; Hillesheim, Patrick C [ORNL; Dai, Sheng [ORNL; Shaw, Robert W [ORNL; Mahurin, Shannon Mark [ORNL



Energy Efficient Electrochromic Windows Incorporating Ionic Liquids  

SciTech Connect

One approach to increasing the energy efficiency of windows is to control the amount of solar radiation transmitted through a window by using electrochromic technology. What is unique about this project is that the electrochromic is based on the reduction/oxidation reactions of cathodic and anodic organic semi-conducting polymers using room temperature ionic liquids as ion transport electrolytes. It is believed that these types of coatings would be a lower cost alternative to traditional all inorganic thin film based electrochromic technologies. Although there are patents1 based on the proposed technology, it has never been reduced to practice and thoroughly evaluated (i.e. durability and performance) in a window application. We demonstrate that by using organic semi-conductive polymers, specific bands of the solar spectrum (specifically visible and near infrared) can be targeted for electrochemical variable transmittance responsiveness. In addition, when the technology is incorporated into an insulating glass unit, the energy parameters such as the solar heat gain coefficient and the light to solar gain ratio are improved over that of a typical insulating glass unit comprised of glass with a low emissivity coating. A minimum of {approx}0.02 quads of energy savings per year with a reduction of carbon emissions for electricity of {approx}320 MKg/yr benefit is achieved over that of a typical insulating glass unit including a double silver low-E coating. Note that these values include a penalty in the heating season. If this penalty is removed (i.e. in southern climates or commercial structures where cooling is predominate year-round) a maximum energy savings of {approx}0.05 quad per year and {approx}801 MKg/yr can be achieved over that of a typical insulating glass unit including a double silver low-E coating. In its current state, the technology is not durable enough for an exterior window application. The primary downfall is that the redox chemistry fails to recover to a bleached state upon exposure to heat and solar radiation while being cycled over time from the bleached to the dark state. Most likely the polymers are undergoing degradation reactions which are accelerated by heat and solar exposure while in either the reduced or oxidized states and the performance of the polymers is greatly reduced over time. For this technology to succeed in an exterior window application, there needs to be more work done to understand the degradation of the polymers under real-life application conditions such as elevated temperatures and solar exposure so that recommendations for improvements in to the overall system can be made. This will be the key to utilizing this type of technology in any future real-life applications.

Cheri Boykin; James Finley; Donald Anthony; Julianna Knowles; Richard Markovic; Michael Buchanan; Mary Ann Fuhry; Lisa Perrine



Unusual redox stability of neptunium in the ionic liquid [Hbet][Tf(2)N].  


The behavior of neptunium in the ionic liquid betaine bistriflimide, [Hbet][Tf2N], has been studied spectroscopically at room temperature and 60 °C for the first time. An unprecedented complex redox chemistry is observed, with up to three oxidation states (iv, v and vi) and up to six Np species existing simultaneously. Both redox reactions and coordination of betaine are observed for Np(iv), (v) and (vi). Elevating the temperature accelerates the coordination of Np(v) with betaine and reduction reactions slow down. PMID:24752760

Long, Kristy; Goff, George; Runde, Wolfgang



Effect of ionic liquid on the structure and tribological properties of polycarbonate–zinc oxide nanodispersion  

Microsoft Academic Search

Room-temperature ionic liquid (IL) 1-hexyl-3-methylimidazolium hexafluorophosphate has been added to PC+0.5 wt.%ZnO nanocomposite in a 1.5 wt.% proportion to obtain PC+0.5%ZnO+1.5%IL. The new PC\\/ZnO\\/IL nanocomposite shows a 80% friction reduction and a wear reduction of nearly two orders of magnitude with respect to PC+0.5%ZnO. The influence of IL on the size, morphology and distribution of ZnO nanoparticles in the PC matrix is

F. J. Carrión; J. Sanes; M. D. Bermúdez



Design and synthesis of C-2 substituted chiral imidazolium ionic liquids from amino acid derivatives.  


[reaction: see text] A series of novel chiral ionic liquids (CILs) has been synthesized and fully characterized. The reaction of 1-methyl-2-imidazolecarboxaldehyde and chiral amino alcohols followed by reduction is key to the design of these new CILs. This is the first time that CILs have been synthesized by introducing chiral scaffolds on the C-2 position of the imidazolium cation of ILs. The simple and straightforward procedure resulted in CILs as colorless oils at room temperature in good yields. PMID:16323882

Ni, Bukuo; Headley, Allan D; Li, Guigen



New Water-Stable Ionic Liquids Based on Tetrakis-(2,2,2-trifluoroethoxy)borate.  


Several new ionic liquids (ILs) were prepared from Na[B(tfe)4] (tfe=OCH2 CF3 ) via metathesis, including one room temperature IL (RTIL). Prior to synthesis, suitable cations were chosen via predictive quantum-chemical calculations. Nuclear magnetic resonance monitoring over almost a month showed a total stability of the anion in the presence of water. The temperature-dependent viscosities and melting points of all the new ILs were determined. The data indicate that [B(tfe)4 ](-) ILs may be too viscous for electrochemical applications, but are interesting candidates for lubricant research. PMID:25209008

Rupp, Alexander B A; Klose, Petra; Scherer, Harald; Krossing, Ingo



Green chemical functionalization of single-walled carbon nanotubes in ionic liquids.  


Single walled carbon nanotubes (SWNTs) are exfoliated and functionalized predominantly as individuals by grinding them for minutes at room temperature with aryldiazonium salts in the presence of ionic liquids (ILs) and K(2)CO(3). This constitutes an extremely rapid and mild green chemical functionalization process for obtaining the individualized nanotube structures. A number of ILs and various reaction conditions were surveyed. Raman, XPS, UV/vis/NIR spectroscopies, thermogravimetric analysis, and atomic force and transmission electron microscopies were used to characterize the products. PMID:16231941

Price, B Katherine; Hudson, Jared L; Tour, James M



Evaluation of Vapor Pressure and Ultra-High Vacuum Tribological Properties of Ionic Liquids (2) Mixtures and Additives  

NASA Technical Reports Server (NTRS)

Ionic liquids are salts, many of which are typically viscous fluids at room temperature. The fluids are characterized by negligible vapor pressures under ambient conditions. These properties have led us to study the effectiveness of ionic liquids containing both organic cations and anions for use as space lubricants. In the previous paper we have measured the vapor pressure and some tribological properties of two distinct ionic liquids under simulated space conditions. In this paper we will present vapor pressure measurements for two new ionic liquids and friction coefficient data for boundary lubrication conditions in a spiral orbit tribometer using stainless steel tribocouples. In addition we present the first tribological data on mixed ionic liquids and an ionic liquid additive. Post mortem infrared and Raman analysis of the balls and races indicates the major degradation pathway for these two organic ionic liquids is similar to those of other carbon based lubricants, i.e. deterioration of the organic structure into amorphous graphitic carbon. The coefficients of friction and lifetimes of these lubricants are comparable to or exceed these properties for several commonly used space oils.

Morales, Wilfredo; Koch, Victor R.; Street, Kenneth W., Jr.; Richard, Ryan M.



Unravelling nanoconfined films of ionic liquids  

NASA Astrophysics Data System (ADS)

The confinement of an ionic liquid between charged solid surfaces is treated using an exactly solvable 1D Coulomb gas model. The theory highlights the importance of two dimensionless parameters: the fugacity of the ionic liquid, and the electrostatic interaction energy of ions at closest approach, in determining how the disjoining pressure exerted on the walls depends on the geometrical confinement. Our theory reveals that thermodynamic fluctuations play a vital role in the "squeezing out" of charged layers as the confinement is increased. The model shows good qualitative agreement with previous experimental data, with all parameters independently estimated without fitting.

Lee, Alpha A.; Vella, Dominic; Perkin, Susan; Goriely, Alain



Electrowetting based infrared lens using ionic liquids  

NASA Astrophysics Data System (ADS)

We demonstrated an infrared variable focus ionic liquids lens using electrowetting, which could overcome the problems caused by use of water, e.g., evaporation and poor thermostability, while keeping good optical transparency in visible light and near-infrared region. Besides, the type of lens (convex or concave) could be tuned by applied voltage or refractive index of ILs used, and the transmittance was measured to exceed 90% over the spectrum of visible light and near-infrared. We believe this infrared variable focus ionic liquids lens has a great application prospect in both visible light and infrared image systems.

Hu, Xiaodong; Zhang, Shiguo; Liu, Yu; Qu, Chao; Lu, Liujin; Ma, Xiangyuan; Zhang, Xiaoping; Deng, Youquan



Room temperature ionic liquid doped DNA network immobilized horseradish peroxidase biosensor for amperometric determination of hydrogen peroxide  

Microsoft Academic Search

A novel electrochemical H2O2 biosensor was constructed by embedding horseradish peroxide (HRP) in a 1-butyl-3-methylimidazolium tetrafluoroborate doped\\u000a DNA network casting on a gold electrode. The HRP entrapped in the composite system displayed good electrocatalytic response\\u000a to the reduction of H2O2. The composite system could provide both a biocompatible microenvironment for enzymes to keep their good bioactivity and\\u000a an effective pathway

Cunlan Guo; Yonghai Song; Hui Wei; Peicai Li; Li Wang; Lanlan Sun; Yujing Sun; Zhuang Li



Aggregation Behavior of Charged Surfactants and their Mixtures in Ionic Liquids  

NASA Astrophysics Data System (ADS)

Room-temperature ionic liquids (ILs) have been recently explored as extraordinary solvent with potential opportunities for numerous applications. We set out to obtain a better understanding of the aggregation behavior of charged surfactants within ILs. From phase diagrams and isotherms in several distinct ILs, a connection between solubility of the surfactant and the physical properties of the underlying ionic liquid was established. We conclude that the interfacial energy is crucial in determining aggregation behavior while electrostatic interactions can be largely ignored. This study was extended to include mixtures of cationic and anionic surfactants where our data further demonstrate near-complete charge screening. Mixtures of charged surfactants in ILs can therefore be considered as nearly ideal, in sharp contrast to aqueous solutions. The results here give insight into the nature of self-assembly of surfactants in ILs and the interaction between solutes and IL solvents.

Chen, Lang; Bermudez, Harry



Polyoxometalate ionic liquids as self-repairing Acid-resistant corrosion protection.  


Corrosion is a global problem for any metallic structure or material. Herein we show how metals can easily be protected against acid corrosion using hydrophobic polyoxometalate-based ionic liquids (POM-ILs). Copper metal disks were coated with room-temperature POM-ILs composed of transition-metal functionalized Keggin anions [SiW11 O39 TM(H2 O)](n-) (TM=Cu(II) , Fe(III) ) and quaternary alkylammonium cations (Cn H2?n+1 )4 N(+) (n=7-8). The corrosion resistance against acetic acid vapors and simulated "acid rain" was significantly improved compared with commercial ionic liquids or solid polyoxometalate coatings. Mechanical damage to the POM-IL coating is self-repaired in less than one minute with full retention of the acid protection properties. The coating can easily be removed and recovered by rinsing with organic solvents. PMID:25332068

Herrmann, Sven; Kostrzewa, Monika; Wierschem, Andreas; Streb, Carsten



Molecular mechanism of gas adsorption into ionic liquids: A molecular dynamics study  

SciTech Connect

Room temperature ionic liquids (RTILs) have been shown to be versatile and tunable solvents that can be used in many chemical applications. In this study, we developed a dynamical, molecular-scale picture of the gas dissolution and interfacial processes in RTILs using molecular simulations. These simulations can provide the free energies associated with transporting a gas solute across various RTIL interfaces and physical insights into the interfacial properties and transport molecular mechanism of gas sorption processes. For CO2 sorption, the features in the potential of mean force (PMF) of CO2 using both polarizable and non-polarizable force fields are similar qualitatively. However, we observed some quantitative differences, and we describe the causes of these differences in this paper. We also show the significant impact of ionic-liquid chemical structures on the gas sorption process, and we discuss their influence on the H2O transport mechanism.

Dang, Liem X.; Chang, Tsun-Mei



Ionic liquid-stabilized non-spherical gold nanofluids synthesized using a one-step method.  


Ionic liquid (IL)-stabilized non-spherical gold nanofluids have been synthesized by a one-step method in aqueous solution. The whole reaction proceeded in room temperature. In the presence of amino-functionalized ionic liquids, gold nanofluids with long-wave surface plasmon resonance (SPR) absorption (>600 nm) could be obtained by adopting tannic acid as the reductant. The specific SPR absorption was related to the non-spherical gold nanoparticles including gold triangle, decahedra, and icosahedra nanocrystals. All the nanocrystals were observed by transmission electron microscopy. It was deduced that the formation of non-spherical gold nanofluids was related to the hydroxyls in tannic acid while IL acted as the synthesis template. PMID:23092303

Zhang, Hao; Cui, Hua; Yao, Shiwei; Zhang, Kelong; Tao, Haikun; Meng, Haibo



Ionic liquid-stabilized non-spherical gold nanofluids synthesized using a one-step method  

PubMed Central

Ionic liquid (IL)-stabilized non-spherical gold nanofluids have been synthesized by a one-step method in aqueous solution. The whole reaction proceeded in room temperature. In the presence of amino-functionalized ionic liquids, gold nanofluids with long-wave surface plasmon resonance (SPR) absorption (>600 nm) could be obtained by adopting tannic acid as the reductant. The specific SPR absorption was related to the non-spherical gold nanoparticles including gold triangle, decahedra, and icosahedra nanocrystals. All the nanocrystals were observed by transmission electron microscopy. It was deduced that the formation of non-spherical gold nanofluids was related to the hydroxyls in tannic acid while IL acted as the synthesis template. PMID:23092303



Studies on thermal properties of selected aprotic and protic ionic liquids  

SciTech Connect

We describe herein the thermal gravimetric analysis (TGA) and differential scanning calorimetry (DSC) investigations of the thermal properties of selected room-temperature ionic liquids (RTILs). The dependence of the thermal properties on both cation and anion structures of RTILs was systematically studied. The ionic liquids (ILs) investigated here include 28 different imidazolium-based ILs, 22 ammonium-based ILs, and 16 amide-based ILs. In general, these three cation classes exhibit different thermal behaviors but follow a quite systematic trend as expected from the corresponding structural variation. The ILs with bromide as the conjugate anion have lower thermal stabilities than those with bis(trifluoromethane sulfonyl) imide or bis(perfluoroethyl sulfonyl) imide as the conjugate anion. The mass of TGA samples and scan rate were found to have a systematic effect on the decomposition temperature of ILs, highlighting the caution needed in reporting TGA results.

Luo, Huimin [ORNL; Dai, Sheng [ORNL; Huang, Jing-Fang [ORNL



Testing Fundamental Properties of Ionic Liquids for Colloid Microthruster Applications  

NASA Technical Reports Server (NTRS)

NASA's New Millennium Program is scheduled to test a Disturbance Reduction System (DRS) on Space Technology 7 (ST7) as part of the European Space Agency's (ESA's) LISA Pathfinder Mission in late 2009. Colloid Micronewton Thrusters (CMNTs) will be used to counteract forces, mainly solar photon pressure, that could disturb gravitational reference sensors as part of the DRS. The micronewton thrusters use an ionic liquid, a room temperature molten salt, as propellant. The ionic liquid has a number of unusual properties that have a direct impact on thruster design. One of the most important issues is bubble formation before and during operation, especially during rapid pressure transitions from atmospheric to vacuum conditions. Bubbles have been observed in the feed system causing variations in propellant flow rate that can adversely affect thruster control. Bubbles in the feed system can also increase the likelihood that propellant will spray onto surfaces that can eventually lead to shorting high voltage electrodes. Two approaches, reducing the probability of bubble formation and removing bubbles with a new bubble eliminator device in the flow system, were investigated at Busek Co., Inc. and the Jet Propulsion Laboratory (JPL) to determine the effectiveness of both approaches. Results show that bubble formation is mainly caused by operation at low pressure and volatile contaminants in the propellant coming out of solution. A specification for the maximum tolerable level of contamination has been developed, and procedures for providing system cleanliness have been tested and implemented. The bubble eliminator device has also been tested successfully and has been implemented in recent thruster designs at Busek. This paper focuses on the propellant testing work at JPL, including testing of a breadboard level bubble eliminator device.

Anderson, John R.; Plett, Gary; Anderson, Mark; Ziemer, John




EPA Science Inventory

Environmentally friendlier preparations of ionic liquids have been developed that proceed expeditiously under the influence of microwave or ultrasound irradiation conditions using neat reactants, alkylimidazoles and alkyl halides. A number of useful ionic liquids have been prepar...


Comparison of electrodeposition of silver in ionic liquid microemulsions  

Microsoft Academic Search

Both ionic liquid (IL) and water are typical green solvents and have high electric conductivity. The use of IL microemulsions as templates and media for electrochemical synthesis of nano-materials is attractive. In this work, water-in-ionic liquid (W\\/IL) microemulsion and ionic liquid-in-water (IL\\/W) microemulsion were prepared, in which hydrophobic ionic liquid 1-butyl-3-methylimidazolium hexafluorophosphate was used. The cyclic voltammetry (CV) behavior and

Chaopeng Fu; Haihui Zhou; Wencai Peng; Jinhua Chen; Yafei Kuang



Self-healing guar gum and guar gum-multiwalled carbon nanotubes nanocomposite gels prepared in an ionic liquid.  


Guar gum is a galactomannan extracted from the seed of the leguminous shrub Cyamopsis tetragonoloba. It was found to form a soft viscoelastic gel in 1-butyl-3-methylimidazolium chloride, an ionic liquid at an optimized concentration of 10%w/v. A nanocomposite gel of the gum with enhanced strength could be prepared with 0.2%w/v of multiwalled carbon nanotubes (MWCNTs) in the ionic liquid. When the gels thus prepared were subjected to surface fractures or bisected completely, they found to self-heal at room temperature without any external interventions. The self-healing process could be repeated several times. These viscoelastic gel systems showed thixotropic nature and recovery of the storage modulus with time for several cycles was observed upon rheological investigations. The interaction took place between ionic liquid, guar gum and MWCNT was studied by SEM, TEM, FT-IR, powder XRD and rheometry. The results suggested that, upon standing at room temperature development of electrostatic interactions and the van der Waals interactions among the ionic liquid molecules facilitated the formation of reversible noncovalent bonds and eventually activated the self-healing in the gel systems through appropriate chain entanglements. PMID:23987443

Sharma, Mukesh; Mondal, Dibyendu; Mukesh, Chandrakant; Prasad, Kamalesh



Superbase-derived protic ionic liquids with chelating fluorinated anions  

SciTech Connect

Eighteen new protic ionic liquids were synthesized in one step from five organic superbases and five commercially available fluorinated -diketones. Physical properties of the ionic liquids, including thermal decomposition temperature were determined. Nine of the ionic liquids were examined as extraction media for La3+, with some very large distribution coefficients obtained.

Bell, Jason R [ORNL; Luo, Huimin [ORNL; Dai, Sheng [ORNL



Ionic Liquids as Alternatives to Traditional Organic and Inorganic Solvents  

Microsoft Academic Search

\\u000a The physical and chemical properties of ionic liquids are compared to those of traditional solvents. The behaviour of the\\u000a SN2 reaction and Diels-Alder reaction occurring in ionic liquids and common solvents is compared and contrasted. The chemistry\\u000a occurring in several common ionic liquids is also assessed.

Richard M. Pagni


Liquid clathrate formation in ionic liquid-aromatic mixtures.  


1-Alkyl-3-methylimidazolium containing ionic liquids with hexafluorophosphate, bis(trifyl)imide, tetrafluoroborate, and chloride anions form liquid clathrates when mixed with aromatic hydrocarbons; in the system 1,3-dimethylimidazolium hexafluorophosphate-benzene, the aromatic solute could be trapped in the solid state forming a crystalline 2:1 inclusion compound. PMID:12638957

Holbrey, John D; Reichert, W Matthew; Nieuwenhuyzen, Mark; Sheppard, Oonagh; Hardacre, Christopher; Rogers, Robin D



Silica particle stability and settling in protic ionic liquids.  


Silica particle suspensions of 10 wt % have been investigated in the protic ionic liquids (ILs) ethylammonium nitrate (EAN), ethanolammonium nitrate (EtAN), propylammonium nitrate (PAN), and dimethylethylammonium formate (DMEAF). Static and dynamic light scattering reveal that single particles coexist in dynamic equilibrium with flocculated networks at room temperature. These types of systems are classified as weakly flocculated and are quite rare. As weakly flocculated systems generally exist only within a narrow range of conditions, the effect of temperature was probed. When temperature is increased, the thermal motion of suspended particles increases, favoring dispersion, but in ILs suspensions, heating reduces the stabilizing effect of the interfacial structure of the IL. When subjected to a small increase in temperature, particle suspensions in ILs become unstable, indicated by the absence of a peak corresponding to single particles in the light scattering data. For EAN and DMEAF, further increasing temperatures above 40 °C returns the systems to a weakly flocculated state in which thermal energy is sufficient to break particles away from aggregates. Weakly flocculated suspensions in EAN and EtAN settle more rapidly than predicted by the Stokes equation, as the particles spend a significant portion of time in large, rapidly settling flocs. Surprisingly, suspensions in PAN and DMEAF settle slower than predicted. Oscillatory rheology indicates that these suspensions are viscoelastic, due to a persistent, long-range structure in the suspension that slows settling. In aggregated systems, settling is very rapid. PMID:24450614

Smith, Jacob; Webber, Grant Bruce; Warr, Gregory G; Atkin, Rob



Electrochemistry of magnesium electrolytes in ionic liquids for secondary batteries.  


The electrochemistry of Mg salts in room-temperature ionic liquids (ILs) was studied using plating/stripping voltammetry to assess the viability of IL solvents for applications in secondary Mg batteries. Borohydride (BH4(-)), trifluoromethanesulfonate (TfO(-)), and bis(trifluoromethanesulfonyl)imide (Tf2N(-)) salts of Mg were investigated. Three ILs were considered: l-n-butyl-3-methylimidazolium (BMIM)-Tf2N, N-methyl-N-propylpiperidinium (PP13)-Tf2N, and N,N-diethyl-N-methyl(2-methoxyethyl)ammonium (DEME(+)) tetrafluoroborate (BF4(-)). Salts and ILs were combined to produce binary solutions in which the anions were structurally similar or identical, if possible. Contrary to some prior reports, no salt/IL combination appeared to facilitate reversible Mg plating. In solutions containing BMIM(+), oxidative activity near 0.8 V vs Mg/Mg(2+) is likely associated with the BMIM cation, rather than Mg stripping. The absence of voltammetric signatures of Mg plating from ILs with Tf2N(-) and BF4(-) suggests that strong Mg/anion Coulombic attraction inhibits electrodeposition. Cosolvent additions to Mg(Tf2N)2/PP13-Tf2N were explored but did not result in enhanced plating/stripping activity. The results highlight the need for IL solvents or cosolvent systems that promote Mg(2+) dissociation. PMID:25248147

Vardar, Gulin; Sleightholme, Alice E S; Naruse, Junichi; Hiramatsu, Hidehiko; Siegel, Donald J; Monroe, Charles W



Conventional Study on Novel Dicationic Ionic Liquid Inclusion with ?-Cyclodextrin  

PubMed Central

This study focuses on the synthesis and characterization of the inclusion complex of ?-Cyclodextrin (?-CD) with dicationic ionic liquid, 3,3?-(1,4-Phenylenebis [methylene]) bis(1-methyl-1H-imidazol-3-ium) di(bromide) (PhenmimBr). The inclusion complex was prepared at room temperature utilizing conventional kneading technique. Proton (1H) NMR and 2D (1H–1H) COSY NMR were the primary characterization tools employed to verify the formation of the inclusion complex. COSY spectra showed strong correlations between protons of imidazolium and protons of ?-CD which indicates that the imidazolium ring of PhenmimBr has entered the cavity of ?-CD. UV absorption indicated that ?-CD reacts with PhenmimBr to form a 2:1 ?-CD-PhenmimBr complex with an apparent formation constant of 2.61 × 105 mol&?2 L2. Other characterization studies such as UV, FT-IR, XRD, TGA, DSC and SEM studies were also used to further support the formation of the ?-CD-PhenmimBr inclusion complex. PMID:22016662

Mohamad, Sharifah; Surikumaran, Hemavathy; Raoov, Muggundha; Marimuthu, Tilagam; Chandrasekaram, Kumuthini; Subramaniam, Puvaneswary



Conventional study on novel dicationic ionic liquid inclusion with ?-cyclodextrin.  


This study focuses on the synthesis and characterization of the inclusion complex of ?-Cyclodextrin (?-CD) with dicationic ionic liquid, 3,3'-(1,4-Phenylenebis [methylene]) bis(1-methyl-1H-imidazol-3-ium) di(bromide) (PhenmimBr). The inclusion complex was prepared at room temperature utilizing conventional kneading technique. Proton ((1)H) NMR and 2D ((1)H-(1)H) COSY NMR were the primary characterization tools employed to verify the formation of the inclusion complex. COSY spectra showed strong correlations between protons of imidazolium and protons of ?-CD which indicates that the imidazolium ring of PhenmimBr has entered the cavity of ?-CD. UV absorption indicated that ?-CD reacts with PhenmimBr to form a 2:1 ?-CD-PhenmimBr complex with an apparent formation constant of 2.61 × 10(5) mol&(-2) L(2). Other characterization studies such as UV, FT-IR, XRD, TGA, DSC and SEM studies were also used to further support the formation of the ?-CD-PhenmimBr inclusion complex. PMID:22016662

Mohamad, Sharifah; Surikumaran, Hemavathy; Raoov, Muggundha; Marimuthu, Tilagam; Chandrasekaram, Kumuthini; Subramaniam, Puvaneswary



Surface Structure at the Ionic Liquid?Electrified Metal Interface  

Microsoft Academic Search

oom-temperature ionic liquids are a new class of liquids with many important uses in electrical and electrochemical devices. The liquids are composed purely of ions in the liquid state with no solvent. They generally have good elec- trical and ionic conductivity and are electrochemically stable. Since their applications often depend critically on the inter- face structure of the liquid adjacent

Steven Baldelli



Electrochemical properties of the polyethylene oxide-Li(CF3SO2)2N and ionic liquid composite electrolyte  

NASA Astrophysics Data System (ADS)

The electrical conductivity and lithium ion transport properties of the polyethylene oxide (PEO) with lithium salt Li(CF3SO2)2N (LiTFSI) and a room temperature ionic liquid of N-methyl-N-propylpiperdinium bis(fluorosulfonyl)imide (PP13FSI) were examined as a function of the ionic liquid content. The electrical conductivity of PEO18LiTFSI-xPP13FSI increased and the lithium ion transport number decreased with increasing the ionic liquid content. The interface resistance between PEO18LiTFSI-xPP13FSI and lithium metal was dependent on x and the lowest interface resistance was observed in the range of x = 1.2-1.44. The critical current density of lithium deposition and dissolution on lithium metal was reduced and lithium dendrite formation was suppressed by the addition of PP13FSI into PEO18LiTFSI.

Wang, H.; Imanishi, N.; Hirano, A.; Takeda, Y.; Yamamoto, O.



Phase behavior of ionic liquid crystals  

E-print Network

Bulk properties of ionic liquid crystals are investigated using density functional theory. The liquid crystal molecules are represented by ellipsoidal particles with charges located in their center or at their tails. Attractive interactions are taken into account in terms of the Gay-Berne pair potential. Rich phase diagrams involving vapor, isotropic and nematic liquid, as well as smectic phases are found. The dependence of the phase behavior on various parameters such as the length of the particles and the location of charges on the particles is studied.

S. Kondrat; M. Bier; L. Harnau



General impossibility to 'prescribe' diffusion for a geminate pair in a central force field and peculiarities of geminate in ionic liquids.  

SciTech Connect

Given the difficulty of obtaining analytical solutions for the diffusion of interacting geminate pairs of (ion) radicals in liquids, it is common, following the original treatment of Mozumder, to 'prescribe' this diffusion. A demonstration is given that such a prescription is impossible for any interaction potential other than the Coulomb potential. This demonstration suggests the inadequacy of this common approach to modeling geminate pair and spur dynamics in the largest emerging class of organic solvents: room-temperature ionic liquids.

Shkrob, I. A. (Chemical Sciences and Engineering Division)



Room temperature terahertz polariton emitter  

SciTech Connect

Terahertz (THz) range electroluminescence from intersubband polariton states is observed in the ultra strong coupling regime, where the interaction energy between the collective excitation of a dense electron gas and a photonic mode is a significant portion of the uncoupled excitation energy. The polariton's increased emission efficiency along with a parabolic electron confinement potential allows operation up to room temperature in a nonresonant pumping scheme. This observation of room temperature electroluminescence of an intersubband device in the THz range is a promising proof of concept for more powerful THz sources.

Geiser, Markus; Scalari, Giacomo; Castellano, Fabrizio; Beck, Mattias; Faist, Jerome [Institute for Quantum Electronics, ETH Zurich, Wolfgang-Pauli-Strasse 16, 8093 Zurich (Switzerland)



Interactions in ion pairs of protic ionic liquids: Comparison with aprotic ionic liquids  

SciTech Connect

The stabilization energies for the formation (E{sub form}) of 11 ion pairs of protic and aprotic ionic liquids were studied by MP2/6-311G{sup **} level ab initio calculations to elucidate the difference between the interactions of ions in protic ionic liquids and those in aprotic ionic liquids. The interactions in the ion pairs of protic ionic liquids (diethylmethylammonium [dema] and dimethylpropylammonium [dmpa] based ionic liquids) are stronger than those of aprotic ionic liquids (ethyltrimethylammonium [etma] based ionic liquids). The E{sub form} for the [dema][CF{sub 3}SO{sub 3}] and [dmpa][CF{sub 3}SO{sub 3}] complexes (?95.6 and ?96.4 kcal/mol, respectively) are significantly larger (more negative) than that for the [etma][CF{sub 3}SO{sub 3}] complex (?81.0 kcal/mol). The same trend was observed for the calculations of ion pairs of the three cations with the Cl{sup ?}, BF{sub 4}{sup ?}, TFSA{sup ?} anions. The anion has contact with the N–H bond of the dema{sup +} or dmpa{sup +} cations in the most stable geometries of the dema{sup +} and dmpa{sup +} complexes. The optimized geometries, in which the anions locate on the counter side of the cations, are 11.0–18.0 kcal/mol less stable, which shows that the interactions in the ions pairs of protic ionic liquids have strong directionality. The E{sub form} for the less stable geometries for the dema{sup +} and dmpa{sup +} complexes are close to those for the most stable etma{sup +} complexes. The electrostatic interaction, which is the major source of the attraction in the ion pairs, is responsible for the directionality of the interactions and determining the magnitude of the interaction energy. Molecular dynamic simulations of the [dema][TFSA] and [dmpa][TFSA] ionic liquids show that the N–H bonds of the cations have contact with the negatively charged (oxygen and nitrogen) atoms of TFSA{sup ?} anion, while the strong directionality of the interactions was not suggested from the simulation of the [etma][CF{sub 3}SO{sub 3}] ionic liquid.

Tsuzuki, Seiji, E-mail: [Research Initiative of Computational Sciences (RICS), Nanosystem Research Institute, National Institute of Advanced Industrial Science and Technology (AIST), 1-1-1 Umezono, Tsukuba, Ibaraki 305-8568 (Japan)] [Research Initiative of Computational Sciences (RICS), Nanosystem Research Institute, National Institute of Advanced Industrial Science and Technology (AIST), 1-1-1 Umezono, Tsukuba, Ibaraki 305-8568 (Japan); Shinoda, Wataru [Health Research Institute, National Institute of Advanced Industrial Science and Technology (AIST), 1-8-31 Midorigaoka, Ikeda, Osaka 563-8577 (Japan)] [Health Research Institute, National Institute of Advanced Industrial Science and Technology (AIST), 1-8-31 Midorigaoka, Ikeda, Osaka 563-8577 (Japan); Miran, Md. Shah; Kinoshita, Hiroshi; Yasuda, Tomohiro; Watanabe, Masayoshi [Department of Chemistry and Biotechnology, Yokohama National University, 79-5 Tokiwadai, Hodogaya-ku, Yokohama 240-8501 (Japan)] [Department of Chemistry and Biotechnology, Yokohama National University, 79-5 Tokiwadai, Hodogaya-ku, Yokohama 240-8501 (Japan)



Employment of ionic liquid-imbibed polymer gel electrolyte for efficient quasi-solid-state dye-sensitized solar cells  

NASA Astrophysics Data System (ADS)

Volatility of organic solvent in liquid electrolyte has been tremendous obstacle for its application in dye-sensitized solar cells (DSSCs), here we designed an ionic liquid-imbibed polymer gel electrolyte using 1-butyl-3-methylimidazolium chloride ([BMIM]Cl) as solvent, 1-methyl-3-propylimidazolium iodide (MPII) as iodine source, and amphiphilic poly(hydroxyethyl methacrylate/glycerol) [poly(HEMA/GR)] as a placeholder. As an amphiphilic matrix, poly(HEMA/GR) material can swell in ionic liquid electrolyte to form a stable gel, benefiting from its extraordinary absorption. The imbibed ionic liquid electrolyte is stored into interconnected poly(HEMA/GR) framework. Resultant quasi-solid-state electrolyte is honored with high ionic conductivity (14.29 mS cm-1) at room temperature and good retention. The ionic liquid-imbibed poly(HEMA/GR) gel electrolyte-based DSSC gives an overall light-to-electric conversion efficiency of 7.15%. The new concept along with easy fabrication promises the ionic liquid-imbibed gel electrolytes good alternatives in efficient DSSCs.

Li, Qinghua; Tang, Qunwei; Du, Nan; Qin, Yuancheng; Xiao, Jin; He, Benlin; Chen, Haiyan; Chu, Lei



Collective excitations in an ionic liquid.  


Collective dynamics in a representative model of ionic liquids, namely, 1-butyl-3-methylimidazolium chloride, have been revealed by molecular dynamics simulation. Dispersion of energy excitation, omega versus k, of longitudinal acoustic (LA) and transverse acoustic (TA) modes was obtained in the wave vector range 0.17 < k < 1.40 Angstroms(-1), which encompasses the main peak of the static structure factor S(k). Linear dispersion of acoustic modes is observed up to k approximately 0.7 Angstroms(-1). Due to mixing between LA and TA modes, LA spectra display transverselike component, and vice versa. Due to anisotropy in short-time ionic dynamics, acoustic modes achieve distinct limiting omega values at high k when the cation displacement is projected either along the plane or perpendicular to the plane of the imidazolium ring. In charge current spectra, branch with negative dispersion of omega versus k is a signature of optic modes in the simulated ionic liquid. Conductivity kappa estimated by using ionic diffusion coefficients in the Nernst-Einstein equation is higher than the actual kappa calculated by integrating the charge current correlation function. From TA spectra, a wave vector dependent viscosity eta(k) has been evaluated, whose low-k limit gives eta in reasonable agreement with experimental data. PMID:16497063

Urahata, Sérgio M; Ribeiro, Mauro C C



Collective excitations in an ionic liquid  

NASA Astrophysics Data System (ADS)

Collective dynamics in a representative model of ionic liquids, namely, 1-butyl-3-methylimidazolium chloride, have been revealed by molecular dynamics simulation. Dispersion of energy excitation, ? versus k, of longitudinal acoustic (LA) and transverse acoustic (TA) modes was obtained in the wave vector range 0.17ionic dynamics, acoustic modes achieve distinct limiting ? values at high k when the cation displacement is projected either along the plane or perpendicular to the plane of the imidazolium ring. In charge current spectra, branch with negative dispersion of ? versus k is a signature of optic modes in the simulated ionic liquid. Conductivity ? estimated by using ionic diffusion coefficients in the Nernst-Einstein equation is higher than the actual ? calculated by integrating the charge current correlation function. From TA spectra, a wave vector dependent viscosity ?(k ) has been evaluated, whose low-k limit gives ? in reasonable agreement with experimental data.

Urahata, Sérgio M.; Ribeiro, Mauro C. C.



Palladium nanoparticles supported onto ionic carbon nanotubes as robust recyclable catalysts in an ionic liquid.  


Palladium nanoparticles have been deposited onto imidazolium bromide-functionalized ionic MWCNTs through hydrogen reduction of Na2PdCl4 in water without aid of surfactants under extremely mild conditions, and combined with an ionic liquid to create a new recyclable ionic liquid-based catalytic system allowing up to 50 times recycling. PMID:18283343

Chun, Yu Sung; Shin, Ju Yeon; Song, Choong Eui; Lee, Sang-gi



Checkerboard Self-Patterning of an Ionic Liquid Film on Mercury  

SciTech Connect

{angstrom}-resolution studies of room temperature ionic liquid (RTIL) interfaces are scarce, in spite of their long-recognized importance for the science and many applications of RTILs. We present an {angstrom}-resolution x-ray study of a Langmuir film of an RTIL on mercury. At low (high) coverage [90 (50) {angstrom}{sup 2}/molecule] a mono-(bi)layer of surface-parallel molecules is found. The molecules self-assemble in a lateral ionic checkerboard pattern, unlike the uniform-charge, alternate-ion layers of this RTIL at its bulk-solid interface. A 2D-smectic order is found, with molecules packed in parallel stripes, forming long-range order normal to, but none along, the stripes.

L Tamam; B Ocko; H Reichert; M Deutsch



Dissolution enthalpies of cellulose in ionic liquids.  


In this work, interactions between cellulose and ionic liquids were studied calorimetrically and by optical microscopy. Two novel ionic liquids (1,5-Diazabicyclo[4.3.0]non-5-enium propionate and N-methyl-1,5-diazabicyclo[4.3.0]non-5-enium dimethyl phosphate) and 1-ethyl-3-methylimidazolium acetate-water mixtures were used as solvents. Optical microscopy served in finding the extent of dissolution and identifying the dissolution pattern of the cellulose sample. Calorimetric studies identified a peak relating to dissolution of cellulose in solvent. The transition did, however, not indicate complete dissolution, but rather dissolution inside fibre or fibrils. This method was used to study differences between four cellulose samples with different pretreatment or origins. PMID:25256460

Parviainen, Helena; Parviainen, Arno; Virtanen, Tommi; Kilpeläinen, Ilkka; Ahvenainen, Patrik; Serimaa, Ritva; Grönqvist, Stina; Maloney, Thaddeus; Maunu, Sirkka Liisa



Ionic liquids: dissecting the enthalpies of vaporization.  


We calculate the heats of vaporisation for imidazolium-based ionic liquids [C(n)mim][NTf(2)] with n=1, 2, 4, 6, 8 by means of molecular dynamics (MD) simulations and discuss their behavior with respect to temperature and the alkyl chain length. We use a force field developed recently. The different cohesive energies contributing to the overall heats of vaporisations are discussed in detail. With increasing alkyl chain length, the Coulomb contribution to the heat of vaporisation remains constant at around 80 kJ mol(-1), whereas the van der Waals interaction increases continuously. The calculated increase of about 4.7 kJ mol(-1) per CH(2)-group of the van der Waals contribution in the ionic liquid exactly coincides with the increase in the heats of vaporisation for n-alcohols and n-alkanes, respectively. The results support the importance of van der Waals interactions even in systems completely composed of ions. PMID:18283693

Köddermann, Thorsten; Paschek, Dietmar; Ludwig, Ralf



Oligomannan Synthesis Using Ionic Liquid Supported Glycosylation§  

PubMed Central

The synthesis of complex oligosaccharides has been a challenge for researchers. Herein, we describe a strategy for the synthesis of an activated oligomannan 1 that employs ionic liquid (IL) support glycosylation methodology on an IL-tagged mannosyl fluoride donor. This method is capable of rapidly producing linear ?(1?6) oligomannan thioglycosides in a convenient and cost-effective manner without the need of column purification after each glycosylation step. PMID:18069846

Pathak, Ashish K.; Yerneni, Charu K.; Young, Zac; Pathak, Vibha



Dicationic organic salts: gelators for ionic liquids.  


Diimidazolium and dipyrrolidinium organic salts were tested for their ability to gel both organic solvents and ionic liquids. Organic salts containing 1-(1-imidazolylmethyl)-3,5-di-(3'-octylimidazolylmethyl)-benzene and 1-(N-pyrrolidylmethyl)-3,5-di-(N,N-octylpyrrolidylmethyl)-benzene cations were used. In addition to the simple bromide anion, also dianions having a naphthalene core such as 1,5- and 2,6-naphthalenedisulfonate and 2,6-naphthalenedicarboxylate were taken into account. Gelation tests demonstrated that organic salts used were able to harden ionic liquids. The materials obtained were investigated for their thermal stability and also for electric conductivity properties using micro-DSC and dielectric spectroscopy. Furthermore, the opacity of some gel phases was monitored using UV-vis measurements. To obtain information about the gelation mechanism, gel phase formation was studied as a function of time by means of resonance light scattering investigation. Finally, the ability of materials to respond to external stimuli such as magnetic stirring or ultrasound irradiation was also analyzed. Data collected show that different relationships exist among the gelator and the ionic liquid structure, determining the properties of materials and their possible applications. PMID:25330144

D'Anna, Francesca; Rizzo, Carla; Vitale, Paola; Lazzara, Giuseppe; Noto, Renato



Structural modifications of nucleosides in ionic liquids  

PubMed Central

Nucleoside chemistry represents an important research area for drug discovery, as many nucleoside analogs are prominent drugs and have been widely applied for cancer and viral chemotherapy. However, the synthesis of modified nucleosides presents a major challenge, which is further aggravated by poor solubility of these compounds in common organic solvents. Most of the currently available methods for nucleoside modification employ toxic high boiling solvents; require long reaction time and tedious workup methods. As such, there is constant effort to develop process chemistry in alternative medium to limit the use of organic solvents that are hazardous to the environment and can be deleterious to human health. One such approach is to use ionic liquids, which are ‘designer materials’ with unique and tunable physico-chemical properties. Studies have shown that methodologies using ionic liquids are highly efficient and convenient for the synthesis of nucleoside analogs, as demonstrated by the preparation of pharmaceutically important anti-viral drugs. This article summarizes recent efforts on nucleoside modification using ionic liquids. PMID:20178825

Kumar, Vineet; Parmar, Virinder S.; Malhotra, Sanjay V.



Structure of ionic liquid-benzene mixtures.  


Neutron diffraction has been used to investigate the structure of liquid mixtures of 1,3-dimethylimidazolium hexafluorophosphate with benzene. Two concentrations of benzene were investigated, namely, 33 mol % and 67 mol %, and show similar structures in each case. The presence of benzene significantly alters the ionic liquid structure, in particular, in the cation-cation interactions, in agreement with the single-crystal structure described recently (Holbrey, J. D.; Reichert, W. M.; Nieuwenhuyzen, M.; Sheppard, O.; Hardacre, C.; Rogers, R. D. Chem. Commun. 2003, 476). In each case, the data was analyzed using an empirical potential structure refinement process. PMID:16851130

Deetlefs, Maggel; Hardacre, Christopher; Nieuwenhuyzen, Mark; Sheppard, Oonagh; Soper, Alan K



Synthesis and anti-microbial potencies of 1-(2-hydroxyethyl)-3-alkylimidazolium chloride ionic liquids: microbial viabilities at different ionic liquids concentrations.  


Three 1-(2-hydroxyethyl)-3-alkylimidazolium chloride room temperature ionic liquids (ILs) [2OHimC(n)][Cl]; (n=0, 1, 4) have been synthesized from the appropriate imidazole precursors and characterized by IR and NMR spectroscopies and elemental analysis. Their anti-microbial activities were investigated using the well-diffusion method. The viabilities of Escherichia coli, Aeromonas hydrophila, Listeria monocytogenes and Salmonella enterica as a function of IL concentrations were studied. The minimal inhibitory concentrations (MICs) and EC?? values for the present ILs were within the concentration range from 60 to 125 mM and 23 to 73 mM. The anti-microbial potencies of the present ILs were compared to a standard antibiotic, gentamicin. The finding affords additional perspective on the level of ILs toxicity to aquatic lifeforms and yet, this characteristic can be readily harnessed to detect microbial growth and activity. PMID:23107478

Hossain, M Ismail; El-Harbawi, Mohanad; Alitheen, Noorjahan Banu Mohamed; Noaman, Yousr Abdulhadi; Lévêque, Jean-Marc; Yin, Chun-Yang



Biocompatible ionic liquids: a new approach for stabilizing proteins in liquid formulation.  


Ionic liquids (ILs) have shown excellent promise as both solutes and solvents for stabilizing proteins at room temperature. Because many modern drugs are protein-based, these stabilizing characteristics have great potential to provide advances in the field of liquid formulation of therapeutic proteins. However, before these developments can be translated into clinical solutions it is essential to establish data related to the biocompatibility of these ILs. The current work investigates the cytotoxicity of several ILs that were rationally synthesized from natural biomolecules and compounds that have already been approved as excipients for drug formulations. The effect of choline dihydrogen phosphate (choline dhp), choline saccharinate, and 1-butyl 3-methyl imidazolium lactate (bmim lactate) on the metabolic activity of a mouse macrophage cell line (J774) was assessed using the reduction in resazurin as an indicator of activity and, by extension, viability. Two formulations of lysozyme (10 mg/ml and 100 mg/ml) in 80 wt % choline dhp (aq) were prepared and the proteins were evaluated for structural stability immediately following formulation and again at 1 month. Equivalent formulations in 0.1 M Na acetate aqueous buffer were evaluated as controls. A differential scanning microcalorimeter (DSC) was used to evaluate the structural stability on the basis of the unfolding temperature and the enthalpy of unfolding, and a micrococcus lysodiekticus activity test was used to evaluate functional activity. All compounds were found to be relatively benign, with toxicity increasing in the order choline dhpionic liquids. PMID:19640150

Vrikkis, Regina M; Fraser, Kevin J; Fujita, Kyoko; Macfarlane, Douglas R; Elliott, Gloria D



Double-stimuli-responsive spherical polymer brushes with a poly(ionic liquid) core and a thermoresponsive shell.  


The synthesis of poly(ionic liquid) (PIL) nanoparticles grafted with a poly(N-isopropyl acrylamide) (PNIPAM) brush shell is reported, which shows responsiveness to temperature and ionic strength in an aqueous solution. The PIL nanoparticles are first prepared via aqueous dispersion polymerization of a vinyl imidazolium-based ionic liquid monomer, which is purposely designed to bear a distal atom transfer radical polymerization (ATRP) initiating group attached to the long alkyl chain via esterification reaction. The size of the PIL nanoparticles can be readily tuned from 25 to 120 nm by polymerization at different monomer concentrations. PNIPAM brushes are successfully grafted from the surface of the poly(ionic liquid) nanoparticles via ATRP. The stimuli-responsive behavior of the poly(ionic liquid) nanoparticles grafted with PNIPAM brushes (NP-g-PNIPAM) in aqueous phase is studied in detail. Enhanced colloidal stability of the NP-g-PNIPAM brush particles at high ionic strength compared to pure PIL nanoparticles at room temperature is achieved. Above the lower critical solution temperature (LCST) of PNIPAM, the brush particles remain stable, but a decrease in hydrodynamic radius due to the collapse of the PNIPAM brush onto the PIL nanoparticle surface is observed. PMID:24186465

Men, Yongjun; Drechsler, Markus; Yuan, Jiayin



Use of ionic liquid and microwave irradiation as a convenient, rapid and eco-friendly method for synthesis of novel optically active and thermally stable aromatic polyamides containing N-phthaloyl- l-alanine pendent group  

Microsoft Academic Search

An efficient, fast and easy method for synthesis of new optically active and thermally stable aromatic polyamides (PAs) containing pendent phthalimide group and l-alanine flexible side spacer using room temperature ionic liquid (RTIL) by microwave irradiation has been investigated. The results found that RTIL efficiently absorb microwave energy, thus leading to a very high heating rate. All the PAs showed

Shadpour Mallakpour; Zahra Rafiee



Task-Specific Ionic Liquid as the Recyclable Catalyst for the Rapid and Green Synthesis of dihydropyrano[3,2-C]chromene Derivatives  

Microsoft Academic Search

A task-specific ionic liquid, [H3N–CH2–CH2–OH][CH3COO], was successfully applied as an efficient and reusable catalyst for the one-pot domino approach dihydropyrano[3,2-c]chromene derivatives with atom economy in condensation reaction of 4-hydroxycoumarin, aldehydes, and malononitrile in a combinatorial fashion in excellent yields and in short reaction times at room temperature under solvent-free grinding conditions. The products and ionic liquid could be conveniently separated

Hamid Reza Shaterian; Moones Honarmand



Novel room temperature ferromagnetic semiconductors  

SciTech Connect

Today's information world, bits of data are processed by semiconductor chips, and stored in the magnetic disk drives. But tomorrow's information technology may see magnetism (spin) and semiconductivity (charge) combined in one 'spintronic' device that exploits both charge and 'spin' to carry data (the best of two worlds). Spintronic devices such as spin valve transistors, spin light emitting diodes, non-volatile memory, logic devices, optical isolators and ultra-fast optical switches are some of the areas of interest for introducing the ferromagnetic properties at room temperature in a semiconductor to make it multifunctional. The potential advantages of such spintronic devices will be higher speed, greater efficiency, and better stability at a reduced power consumption. This Thesis contains two main topics: In-depth understanding of magnetism in Mn doped ZnO, and our search and identification of at least six new above room temperature ferromagnetic semiconductors. Both complex doped ZnO based new materials, as well as a number of nonoxides like phosphides, and sulfides suitably doped with Mn or Cu are shown to give rise to ferromagnetism above room temperature. Some of the highlights of this work are discovery of room temperature ferromagnetism in: (1) ZnO:Mn (paper in Nature Materials, Oct issue, 2003); (2) ZnO doped with Cu (containing no magnetic elements in it); (3) GaP doped with Cu (again containing no magnetic elements in it); (4) Enhancement of Magnetization by Cu co-doping in ZnO:Mn; (5) CdS doped with Mn, and a few others not reported in this thesis. We discuss in detail the first observation of ferromagnetism above room temperature in the form of powder, bulk pellets, in 2-3 mu-m thick transparent pulsed laser deposited films of the Mn (<4 at. percent) doped ZnO. High-resolution transmission electron microscopy (HRTEM) and electron energy loss spectroscopy (EELS) spectra recorded from 2 to 200nm areas showed homogeneous distribution of Mn substituting for Zn a 2+ state in the ZnO lattice. Ferromagnetic Resonance (FMR) technique is used to confirm the existence of ferromagnetic ordering at temperatures as high as 425K. The ab initio calculations were found to be consistent with the observation of ferromagnetism arising from fully polarized Mn 2+ state. The key to observed room temperature ferromagnetism in this system is the low temperature processing, which prevents formation of clusters, secondary phases and the host ZnO from becoming n-type. The electronic structure of the same Mn doped ZnO thin films studied using XAS, XES and RIXS, revealed a strong hybridization between Mn 3d and O 2p states, which is an important characteristic of a Dilute magnetic Semiconductor (DMS). It is shown that the various processing conditions like sintering temperature, dopant concentration and the properties of precursors used for making of DMS have a great influence on the final properties. Use of various experimental techniques to verify the physical properties, and to understand the mechanism involved to give rise to ferromagnetism is presented. Methods to improve the magnetic moment in Mn doped ZnO are also described. New promising DMS materials (such as Cu doped ZnO are explored). The demonstrated new capability to fabricate powder, pellets, and thin films of room temperature ferromagnetic semiconductors thus makes possible the realization of a wide range of complex elements for a variety of new multifunctional phenomena related to Spintronic devices as well as magneto-optic components.

Gupta, Amita



Phase Behavior of Block Copolymer Solutions in an Ionic Liquid  

Microsoft Academic Search

Incorporation of ionic liquids into block copolymers is of interest for applications such as high temperature fuel cell membranes. We investigate the lyotropic and thermotropic phase behavior of solutions of poly(styrene-b-2-vinyl pyridine) (S2VP) block copolymers in an ionic liquid consisting of imidazole and bis(trifluoromethane)sulfonamide (HTFSI). Using small angle X-ray scattering (SAXS) and static birefringence, we demonstrate that the ionic liquid

J. M. Virgili; M. L. Hoarfrost; N. P. Balsara; R. A. Segalman



Electrocatalytic oxidation of dopamine at an ionic liquid modified carbon paste electrode and its analytical application.  


A room-temperature ionic liquid N-butylpyridinium hexafluorophosphate was used as a binder to construct an ionic liquid modified carbon paste electrode, which was characterized by scanning electron microscopy and electrochemical impedance spectroscopy. The ionic liquid carbon paste electrode (IL-CPE) showed enhanced electrochemical response and strong analytical activity towards the electrochemical oxidation of dopamine (DA). A pair of well-defined quasireversible redox peaks of DA appeared, with the redox peaks located at 215 mV (E (pa)) and 151 mV (E (pc)) (vs. the saturated calomel electrode, SCE) in pH 6.0 phosphate buffer solution. The formal potential (E (0')) was calculated as 183 mV (vs. SCE) and the peak-to-peak separation as 64 mV. The electrochemical behavior of DA on the IL-CPE was carefully investigated. Under the optimal conditions, the anodic peak currents increased linearly with the concentration of DA in the range 1.0 x 10(-6)-8.0 x 10(-4) mol/L and the detection limit was calculated as 7.0 x 10(-7) mol/L (3sigma). The interferences of foreign substances were investigated and the proposed method was successfully applied to the determination of DA injection samples. The IL-CPE fabricated was sensitive, selective and showed good ability to distinguish the coexisting ascorbic acid and uric acid. PMID:17701400

Sun, Wei; Yang, Maoxia; Jiao, Kui



On the radiation stability of crown ethers in ionic liquids.  

SciTech Connect

Crown ethers (CEs) are macrocyclic ionophores used for the separation of strontium-90 from acidic nuclear waste streams. Room temperature ionic liquids (ILs) are presently being considered as replacements for traditional molecular solvents employed in such separations. It is desirable that the extraction efficacy obtained with such solvents should not deteriorate in the strong radiation fields generated by decaying radionuclides. This deterioration will depend on the extent of radiation damage to both the IL solvent and the CE solute. While radiation damage to ILs has been extensively studied, the issue of the radiation stability of crown ethers, particularly in an IL matrix, has not been adequately addressed. With this in mind, we have employed electron paramagnetic resonance (EPR) spectroscopy to study the formation of CE-related radicals in the radiolysis of selected CEs in ILs incorporating aromatic (imidazolium and pyridinium) cations. The crown ethers have been found to yield primarily hydrogen loss radicals, H atoms, and the formyl radical. In the low-dose regime, the relative yield of these radicals increases linearly with the mole fraction of the solute, suggesting negligible transfer of the excitation energy from the solvent to the solute; that is, the solvent has a 'radioprotective' effect. The damage to the CE in the loading region of practical interest is relatively low. Under such conditions, the main chemical pathway leading to decreased extraction performance is protonation of the macrocycle. At high radiation doses, sufficient to increase the acidity of the IL solvent significantly, such proton complexes compete with the solvent cations as electron traps. In this regime, the CEs will rapidly degrade as the result of H abstraction from the CE ring by the released H atoms. Thus, the radiation dose to which a CE/IL system is exposed must be maintained at a level sufficiently low to avoid this regime.

Shkrob, I.; Marin, T.; Dietz, M. (Chemical Sciences and Engineering Division); (Benedictine Univ.); (Univ. of Wisconsin at Milwaukee)



Lipid extraction from microalgae using a single ionic liquid  


A one-step process for the lysis of microalgae cell walls and separation of the cellular lipids for use in biofuel production by utilizing a hydrophilic ionic liquid, 1-butyl-3-methylimidazolium. The hydrophilic ionic liquid both lyses the microalgae cell walls and forms two immiscible layers, one of which consists of the lipid contents of the lysed cells. After mixture of the hydrophilic ionic liquid with a suspension of microalgae cells, gravity causes a hydrophobic lipid phase to move to a top phase where it is removed from the mixture and purified. The hydrophilic ionic liquid is recycled to lyse new microalgae suspensions.

Salvo, Roberto Di; Reich, Alton; Dykes, Jr., H. Waite H.; Teixeira, Rodrigo



Electrodeposition of 3D ordered macroporous germanium from ionic liquids: a feasible method to make photonic crystals with a high dielectric constant.  


A promising method for the production of germanium photonic crystals consists of electrodeposition of Ge from GeCl(4)-containing ionic liquids inside templates of polystyrene colloidal crystals and subsequent removal of the template. This room-temperature method gives rise to the fabrication of a three-dimensional highly ordered macroporous germanium nanostructure (see picture; scale: 2 microm) as a prototype of a photonic crystal. PMID:19267378

Meng, Xiangdong; Al-Salman, Rihab; Zhao, Jiupeng; Borissenko, Natalia; Li, Yao; Endres, Frank



A study on the electrodeposition of tantalum on NiTi alloy in an ionic liquid and corrosion behaviour of the coated alloy  

Microsoft Academic Search

The present paper deals with the electroplating of tantalum on NiTi alloy in the room temperature ionic liquid 1-butyl-1-methyl-pyrrolidinium bis(tri-fluoromethylsulfonyl)imide ([BMP]Tf2N) containing TaF5 as a source of tantalum, as well as studying the corrosion behaviour of the coated alloy. The study comprised cyclic voltammetry, chronoamperometry, open circuit potential and potentiodynamic polarization measurements complemented by SEM-EDAX investigations. The results show that

S. Zein El Abedin; U. Welz-Biermann; F. Endres



Determination of solubility parameters of ionic liquids and ionic liquid/solvent mixtures from intrinsic viscosity.  


The total and partial solubility parameters (dispersion, polar and hydrogen-bonding solubility parameters) of ten ionic liquids were determined. Intrinsic viscosity approaches were used that encompassed a one-dimensional method (1D-Method), and two different three-dimensional methods (3D-Method1 and 3D-Method2). The effect of solvent type, the dimethylacetamide (DMA) fraction in the ionic liquid, and dissolution temperature on solubility parameters were also investigated. For all types of effect, both the 1D-Method and 3D-Method2 present the same trend in the total solubility parameter. The partial solubility parameters are influenced by the cation and anion of the ionic liquid. Considering the effect on partial solubility parameters of the solvent type in the ionic liquid, it was observed that in both 3D methods, the dispersion and polar parameters of a 1-ethyl-3-methylimidazolium acetate/solvent (60:40 vol?%) mixture tend to increase as the total solubility parameter of the solvent increases. PMID:25145759

Weerachanchai, Piyarat; Wong, Yuewen; Lim, Kok Hwa; Tan, Timothy Thatt Yang; Lee, Jong-Min



Aprotic Heterocyclic Anion Triazolide Ionic Liquids - A New Class of Ionic Liquid Anion Accessed by the Huisgen Cycloaddition Reaction  

SciTech Connect

The triazole core is a highly versatile heterocyclic ring which can be accessed easily with the Cu(I)-catalyzed Huisgen cycloaddition reaction. Herein we present the preparation of ionic liquids that incorporate a 1,2,3-triazolide anion. These ionic liquids were prepared by a facile procedure utilizing a base-labile pivaloylmethyl group at the 1-position, which can act as precursors to 1H- 4-substituted 1,2,3-triazole. These triazoles were then subsequently converted into ionic liquids after deprotonation using an appropriate ionic liquid cation hydroxide. The densities and thermal decompositions of these ionic liquids were measured. These novel ionic liquids have potential applications in gas separations and in metal-free catalysis.

Thompson, Robert L.; Damodaran, Krishnan; Luebke, David; Nulwala, Hunaid



Using Artificial Neural Network to Predict the Ternary Electrical Conductivity of Ionic Liquid Systems  

Microsoft Academic Search

The unique physical properties of ionic liquids play a decisive part in many of their applications. Therefore, the ability to predict the physical properties of ionic liquids is extremely important for the rational design of proper ionic liquids with specific properties. In practice, the processes involving ionic liquids usually contain other components, in addition to the ionic liquids. Therefore, in

Ali Zeinolabedini Hezave; Mostafa Lashkarbolooki; Sona Raeissi


Toxicity of ionic liquids prepared from biomaterials.  


In search of environmentally-friendly ionic liquids (ILs), 14 were prepared based on the imidazolium, pyridinium and choline cations, with bromide and several amino acids as anions. Good yields were obtained in the synthesis of pyridinium ILs and those prepared from choline and amino acids. Four of the ILs synthesized from choline and the amino acids arginine, glutamine, glutamic acid and cystine are described here for the first time. The toxicity of the synthesized ILs was checked against organisms of various levels of organization: the crustacean Artemia salina; Human cell HeLa (cervical carcinoma); and bacteria with different types of cell wall, Bacillus subtilis and Escherichia coli. The toxicity was observed to depend on both the cation and anion. Choline-amino acid ILs showed a remarkable low toxicity to A. salina and HeLa cell culture, ten times less than imidazolium and pyridinium ILs. None of ionic liquids exhibited marked toxicity to bacteria, and the effect was 2-3 orders of magnitude smaller than that of the antibiotic chloramphenicol. PMID:24268343

Gouveia, W; Jorge, T F; Martins, S; Meireles, M; Carolino, M; Cruz, C; Almeida, T V; Araújo, M E M



A New Category of Liquid Salt--Liquid Ionic Phosphates (LIPs)  

Microsoft Academic Search

Starting with polycationic ammonium and phosphonium salts bearing halide anions previously synthesized in our laboratory, we have prepared a new category of nonaqueous ionic liquids. These new nonaqueous ionic liquids bear either free phosphate anions or partially esterified phosphate anions as the counterions to the ammonium or phosphonium cations. We generally refer to these new species as LIPs (liquid ionic

Robert Engel; Jaimelee Iolani Cohen; Sharon I. Lall



Electrochemical reduction of an anion for ionic-liquid molecules on a lithium electrode studied by first-principles calculations  

NASA Astrophysics Data System (ADS)

We report ab initio molecular dynamics studies with electric field that reveal chemical stability of room temperature ionic liquid for charge transfer from lithium and nickel electrodes. Bis(trifluoromethanesulfonyl)imide (TFSI) is oxidized on the nickel electrode under a high positive bias condition as expected. However, TFSI is reduced on the lithium electrode under both positive and negative bias conditions, because the lithium electrode acts as a strong reductant. The decomposition of TFSI anion might induce the formation of LiF as a solid electrolyte interphase, which could restrain the TFSI reduction. The stability of an cation under reductant conditions is presented.

Ando, Yasunobu; Kawamura, Yoshiumi; Ikeshoji, Tamio; Otani, Minoru



New Single-Walled Carbon Nanotubes–Ionic Liquid Lubricant. Application to Polycarbonate–Stainless Steel Sliding Contact  

Microsoft Academic Search

Single-walled carbon nanotubes (NTs) were added in a 0.5 wt% proportion to the room temperature ionic liquid (IL) 1-octyl,\\u000a 3-methylimidazolium chloride ([OMIM]Cl). The [OMIM]Cl + NT mixtures obtained by mechanical grinding in an agate mortar ([OMIM]Cl + NT(g))\\u000a or by mechanical grinding and ultrasound dispersion ([OMIM]Cl + NT(g + us)) were used as lubricants of the polycarbonate (PC)\\u000a disc\\/AISI 316L stainless steel pin contact. When the [OMIM]Cl + NT(g + us) dispersion is

Francisco J. CarrionJoseSanes; José Sanes; María-Dolores Bermúdez; Alejandro Arribas



Performance of Multi Walled Carbon Nanotubes Grown on Conductive Substrates as Supercapacitors Electrodes using Organic and Ionic liquid electrolytes  

NASA Astrophysics Data System (ADS)

In this work we will present the use of Multi Walled Carbon Nanotubes (MWNT) directly grown on inconel substrates via chemical vapor deposition, as electrode materials for electrochemical double layer capacitors (EDLC). The performance of the MWNT EDLC electrodes were investigated using two electrolytes, an organic electrolyte, tetraethylammonium tetrafluoroborate in propylene carbonate (Et4NBF4 in PC), and a room temperature ionic liquid, 1-butyl-3-methylimidazolium hexafluorophosphate (BMIM-PF6). Cyclic voltammetry, galvanostatic charge-discharge, and electrochemical impedance spectroscopy measurements to obtain values for the capacitance and internal resistance of these devices will be presented and compared.

Winchester, Andrew; Ghosh, Sujoy; Turner, Ben; Zhang, X. F.; Talapatra, Saikat



Tetraalkylphosphonium polyoxometalates : Electroactive, 'task-specific' ionic liquids.  

SciTech Connect

The pairing of selected polyoxometalate (POM) anions with appropriate tetraalkylphosphonium cations is shown to yield an original family of ionic liquids, among them an ambient-temperature 'liquid POM.'

Rickert, P. G.; Antonio, M. R.; Firestone, M. A.; Kubatko, K-A.; Szreder, T.; Wishart, J. F.; Dietz, M. L.; BNL; Univ. of Miami



Proton Transport in Nanostructured Block Copolymer\\/Ionic Liquid Membranes  

Microsoft Academic Search

Nanostructured block copolymer\\/ionic liquid mixtures are of interest for creating membranes having high proton conductivity coupled with high thermal stability. In these mixtures, it is anticipated that nanoconfinement to block copolymer domains will affect ionic liquid proton transport properties. Using pulsed-field gradient NMR and quasi-elastic neutron scattering, this relationship has been investigated for mixtures of poly(styrene-b- 2-vinylpyridine) (S2VP) with ionic

Megan Hoarfrost; Madhu Tyagi; Jeffrey Reimer; Rachel Segalman



Multi-responsive ionic liquid emulsions stabilized by microgels.  


We present a complete toolbox to use responsive ionic liquid (IL) emulsions for extraction purposes. IL emulsions stabilized by responsive microgels are shown to allow rapid extraction and reversible breaking and re-emulsification. Moreover, by using a paramagnetic ionic liquid, droplets can be easily collected in low magnetic fields. PMID:25177844

Monteillet, Hélène; Workamp, Marcel; Li, Xiaohua; Schuur, Boelo; Kleijn, J Mieke; Leermakers, Frans A M; Sprakel, Joris



Brownian dynamics determine universality of charge transport in ionic liquids  

SciTech Connect

Broadband dielectric spectroscopy is employed to investigate charge transport in a variety of glass-forming ionic liquids over wide frequency, temperature and pressure ranges. Using a combination of Einstein, Einstein-Smoluchowski, and Langevin relations, the observed universal scaling of charge transport in ionic liquids is traced back to the dominant role of Brownian dynamics.

Sangoro, Joshua R [ORNL; Iacob, Ciprian [University of Leipzig; Mierzwa, Michal [University of Silesia, Uniwersytecka, Katowice, Poland; Paluch, Marian [University of Silesia, Uniwersytecka, Katowice, Poland; Kremer, Friedrich [University of Leipzig



Purification or contamination? The effect of sorbents on ionic liquids.  


Commonly used for purification, alumina and silica are found to contaminate ionic liquids with particles; these particles cannot be removed easily and can have a non-negligible impact on the electrochemical, spectroscopic and physical properties of an ionic liquid, including its nucleation and crystallisation kinetics. PMID:18535709

Clare, Bronya R; Bayley, Paul M; Best, Adam S; Forsyth, Maria; MacFarlane, Douglas R



Friedel-Crafts acylation of aromatics catalysed by supported ionic liquids  

Microsoft Academic Search

Different ionic liquids were used as catalysts for Friedel-Crafts acylation reactions. Supported chloroferrate ionic liquids were tested in liquid and in gas phase reactions. The catalysts, consisting of the ionic liquid and charcoal as a carrier, are easy to prepare and show interesting catalytic properties. Comparisons between different ionic liquids in the liquid phase are presented, as well as reactions

M. H Valkenberg; C deCastro; W. F Hölderich



Monoenergetic source of kilodalton ions from Taylor cones of ionic liquids  

NASA Astrophysics Data System (ADS)

The ionic liquid ion sources (ILISs) recently introduced by Lozano and Martinez Sanchez [J. Colloid Interface Sci. 282, 415 (2005)], based on electrochemically etched tungsten tips as emitters for Taylor cones of ionic liquids (ILs), have been tested with ionic liquids [A+B-] of increasing molecular weight and viscosity. These ILs have electrical conductivities well below 1S/m and were previously thought to be unsuitable to operate in the purely ionic regime because their Taylor cones produce mostly charged drops from conventional capillary tube sources. Strikingly, all the ILs tried on ILIS form charged beams composed exclusively of small ions and cluster ions A+(AB)n or B-(AB)n, with abundances generally peaking at n =1. Particularly interesting are the positive and negative ion beams produced from the room temperature molten salts 1-methyl-3-pentylimidazolium tris(pentafluoroethyl) trifluorophosphate (C5MI-(C2F5)3PF3) and 1-ethyl-3-methylimidazolium bis(pentafluoroethyl) sulfonylimide (EMI-(C2F5SO3)2N). We extend to these heavier species the previous conclusions from Lozano and Martinez Sanchez on the narrow energy distributions of the ion beams. In combination with suitable ILs, this source yields nanoamphere currents of positive and negative monoenergetic molecular ions with masses exceeding 2000amu. Potential applications are in biological secondary ion mass spectrometry, chemically assisted high-resolution ion beam etching, and electrical propulsion. Advantages of the ILISs versus similar liquid metal ion sources include the possibility to form negative as well as positive ion beams and a much wider range of ion compositions and molecular masses.

Larriba, C.; Castro, S.; Fernandez de la Mora, J.; Lozano, P.



MD simulations of the formation of stable clusters in mixtures of alkaline salts and imidazolium-based ionic liquids.  


Structural and dynamical properties of room-temperature ionic liquids containing the cation 1-butyl-3-methylimidazolium ([BMIM](+)) and three different anions (hexafluorophosphate, [PF6](-), tetrafluoroborate, [BF4](-), and bis(trifluoromethylsulfonyl)imide, [NTf2](-)) doped with several molar fractions of lithium salts with a common anion at 298.15 K and 1 atm were investigated by means of molecular dynamics simulations. The effect of the size of the salt cation was also analyzed by comparing these results with those for mixtures of [BMIM][PF6] with NaPF6. Lithium/sodium solvation and ionic mobilities were analyzed via the study of radial distribution functions, coordination numbers, cage autocorrelation functions, mean-square displacements (including the analysis of both ballistic and diffusive regimes), self-diffusion coefficients of all the ionic species, velocity and current autocorrelation functions, and ionic conductivity in all the ionic liquid/salt systems. We found that lithium and sodium cations are strongly coordinated in two different positions with the anion present in the mixture. Moreover, [Li](+) and [Na](+) cations were found to form bonded-like, long-lived aggregates with the anions in their first solvation shell, which act as very stable kinetic entities within which a marked rattling motion of salt ions takes place. With very long MD simulation runs, this phenomenon is proved to be on the basis of the decrease of self-diffusion coefficients and ionic conductivities previously reported in experimental and computational results. PMID:23480174

Méndez-Morales, Trinidad; Carrete, Jesús; Bouzón-Capelo, Silvia; Pérez-Rodríguez, Martín; Cabeza, Óscar; Gallego, Luis J; Varela, Luis M



Solid-ionic liquid interfaces: pore filling revisited.  


The properties of ionic liquids on ordered and non-ordered mesoporous silicas (silica gel, MCM-41, SBA-15) were studied by nitrogen sorption, mercury intrusion and thermogravimetric analyses, as well as (129)Xe-NMR spectroscopy. The ionic liquids investigated are based on the 1-hexyl-3-methylimidazolium cation, which was combined with anions of low (bis(trifluoromethanesulfonyl)imide; [NTf2](-)), medium (trifluoromethylsulfonate; [CF3SO3](-)) to high (acetate; [OAc](-)) basicity. The surface coverage depends on both the type of ionic liquid and support used. This results not only in layer or droplet formation, but also in different physico-chemical properties of the ionic liquid when compared to the bulk, depending mainly on the strength of interaction at the interface. Furthermore, the mercury intrusion analysis of mesopores is shown not to be suitable for supported ionic liquids. PMID:25300707

Heinze, M T; Zill, J C; Matysik, J; Einicke, W D; Gläser, R; Stark, A



Non-aqueous aluminium-air battery based on ionic liquid electrolyte  

NASA Astrophysics Data System (ADS)

A promising metal-air secondary battery based on aluminium-oxygen couple is described. In this paper, we observed that an aluminium-air battery employing EMImCl, AlCl3 room temperature ionic liquid (RTIL) as electrolyte and aluminium as negative electrode, has an exceptional reduced self-discharged rate. Due to its new and innovative type of electrolyte, this aluminium-air battery can support relatively high current densities (up to 0.6 mA cm-2) and an average voltage of 0.6-0.8 V. Such batteries may find immediate applications, as they can provide an internal, built-in autonomous and self-sustained energy source.

Revel, Renaud; Audichon, Thomas; Gonzalez, Serge



Speciation of zinc in nano phosphor particulars abstracted in an ionic liquid  

NASA Astrophysics Data System (ADS)

Nano size (<100 nm) pollutants have been controlled negligibly in traditional air pollution control devices. Phosphor particulates escaped from filtration systems (bag houses or electrostatic precipitators) of used TVs, monitors or FEDs disassembling processes are frequently found in nano or submicron sizes. Experimentally, in a very short contact time (<2 min), more than 90% of the nano phosphor particulates could be abstracted into room temperature ionic liquid (RTIL) (e.g., [C 4min][PF 6]). The least-square fitted X-ray absorption near edge structural (XANES) spectra show that nano ZnS (88%) and ZnO (12%) could be suspended in the RTIL for at least 10 days.

Hsu, H. H.; Huang, J. H.; Paul Wang, H.; Jou, C. J. G.



Mesoporous Silica Materials Synthesized via Sol-Gel Methods Modified with Ionic Liquid and Surfactant Molecules  

NASA Astrophysics Data System (ADS)

Mesoporous silica materials were synthesized via a sol-gel method employing a room temperature ionic liquid (1-butyl-3-methylimidazolium tetrafluoroborate, [bmim][BF4]) as a new solvent medium and further modified with surfactant (hexadecyl-trimethyl-ammonium bromide, CTAB) as a pore templating material. The synthesized samples were characterized by the transmission electron microscopy, X-ray diffraction, and N2 adsorption-desorption techniques. The results indicated that the mesoporous silica synthesized by using [bmim][BF4] and CTAB as mixed templates showed better mesostructural order and smaller pore size, compared with mesoporous silica materials synthesized by using single [bmim][BF4] as template under the same conditions. This indicates that the presence of surfactant can affect the microstructures of silica prepared by the present synthesis method.

Xu, Cun-ying; Tang, Ru-lan; Hua, Yi-xin; Zhang, Peng-xiang



Bioanalytical separation and preconcentration using ionic liquids.  


Ionic liquids (ILs) are novel solvents that display a number of unique properties, such as negligible vapor pressure, thermal stability (even at high temperatures), favorable viscosity, and miscibility with water and organic solvents. These properties make them attractive alternatives to environmentally unfriendly solvents that produce volatile organic compounds. In this article, a critical review of state-of-the-art developments in the use of ILs for the separation and preconcentration of bioanalytes in biological samples is presented. Special attention is paid to the determination of various organic and inorganic analytes--including contaminants (e.g., pesticides, nicotine, opioids, gold, arsenic, lead, etc.) and functional biomolecules (e.g., testosterone, vitamin B12, hemoglobin)--in urine, blood, saliva, hair, and nail samples. A brief introduction to modern microextraction techniques based on ILs, such as dispersive liquid-liquid microextraction (DLLME) and single-drop microextraction (SDME), is provided. A comparison of IL-based methods in terms of their limits of detection and environmental compatibilities is also made. Finally, critical issues and challenges that have arisen from the use of ILs in separation and preconcentration techniques are also discussed. PMID:23681199

Escudero, Leticia B; Castro Grijalba, Alexander; Martinis, Estefanía M; Wuilloud, Rodolfo G



Carbon Dioxide and Ionic Liquid Refrigerants: Compact, Efficient Air Conditioning with Ionic Liquid-Based Refrigerants  

SciTech Connect

BEETIT Project: Notre Dame is developing an air-conditioning system with a new ionic liquid and CO2 as the working fluid. Synthetic refrigerants used in air conditioning and refrigeration systems are potent GHGs and can trap 1,000 times more heat in the atmosphere than CO2 alone—making CO2 an attractive alternative for synthetic refrigerants in cooling systems. However, operating cooling systems with pure CO2 requires prohibitively high pressures and expensive hardware. Notre Dame is creating a new fluid made of CO2 and ionic liquid that enables the use of CO2 at low pressures and requires minimal changes to existing hardware and production lines. This new fluid also produces no harmful emissions and can improve the efficiency of air conditioning systems— enabling new use of CO2 as a refrigerant in cooling systems.




Energy storage materials synthesized from ionic liquids.  


The advent of ionic liquids (ILs) as eco-friendly and promising reaction media has opened new frontiers in the field of electrochemical energy storage. Beyond their use as electrolyte components in batteries and supercapacitors, ILs have unique properties that make them suitable as functional advanced materials, media for materials production, and components for preparing highly engineered functional products. Aiming at offering an in-depth review on the newly emerging IL-based green synthesis processes of energy storage materials, this Review provides an overview of the role of ILs in the synthesis of materials for batteries, supercapacitors, and green electrode processing. It is expected that this Review will assess the status quo of the research field and thereby stimulate new thoughts and ideas on the emerging challenges and opportunities of IL-based syntheses of energy materials. PMID:25303401

Gebresilassie Eshetu, Gebrekidan; Armand, Michel; Scrosati, Bruno; Passerini, Stefano



Ionic liquid-assisted preparation of laccase-based biocathodes with improved biocompatibility.  


Laccase enzyme has been widely used as the catalyst of the biocathodes in enzymatic biofuel cells (BFCs); the poor biocompatibility of this enzyme (e.g., poor catalytic activity in neutral media and low tolerance against chloride ion) and the lack of selectivity for oxygen reduction at the laccase-based biocathode against ascorbic acid, unfortunately, offer a great limitation to future biological applications of laccase-based BFCs. This study demonstrates a facial yet effective solution to these limitations with the assistance of hydrophobic room temperature ionic liquid, 1-butyl-3-methylimidazolium hexafluorophosphate (Bmim(+)PF(6)(-)). With the Bmim(+)PF(6)(-) overcoating, the laccase-based biocathodes possess a good bioelectrocatalytic activity toward O(2) reduction in neutral media and a high tolerance against Cl(-). Moreover, the Bmim(+)PF(6)(-) overcoating applied to the laccase-based biocathodes also well suppresses the oxidation of ascorbic acid (AA) at the biocathodes and thereby avoids the AA-induced decrease in the power output of the laccase-based BFCs. The mechanisms underlying the excellent properties of the Bmim(+)PF(6)(-) overcoating are proposed based on the intrinsic features of ionic liquid Bmim(+)PF(6)(-). To demonstrate the applications of the BFCs with the as-prepared biocathodes in biologically relevant systems, an AA/O(2) BFC is assembled with single-walled carbon nanotubes (SWNTs) as electrode materials both for accelerating AA oxidation at the bioanode and for promoting direct electron transfer of laccase at the biocathode. With the presence of 0.50 mM AA in 0.10 M quiescent phosphate buffer (pH 7.2), the assembled BFC has an open circuit voltage of 0.73 V and a maximum power output of 24 ?W cm(-2) at 0.40 V under ambient air and room temperature. This study essentially offers a new strategy for the development of enzymatic BFCs with a high biocompatibility. PMID:22497437

Qian, Qin; Su, Lei; Yu, Ping; Cheng, Hanjun; Lin, Yuqing; Jin, Xiaoyong; Mao, Lanqun



Combustible ionic liquids by design: is laboratory safety another ionic liquid myth?  


The non-flammability of ionic liquids (ILs) is often highlighted as a safety advantage of ILs over volatile organic compounds (VOCs), but the fact that many ILs are not flammable themselves does not mean that they are safe to use near fire and/or heat sources; a large group of ILs (including commercially available ILs) are combustible due to the nature of their positive heats of formation, oxygen content, and decomposition products. PMID:16779475

Smiglak, Marcin; Reichert, W Mathew; Holbrey, John D; Wilkes, John S; Sun, Luyi; Thrasher, Joseph S; Kirichenko, Kostyantyn; Singh, Shailendra; Katritzky, Alan R; Rogers, Robin D



Phase equilibria study of the binary systems (N-hexylisoquinolinium thiocyanate ionic liquid + organic solvent or water).  


Liquid-liquid phase equilibria (LLE) of binary mixtures containing a room-temperature ionic liquid N-hexylisoquinolinium thiocyanate, [HiQuin][SCN] with an aliphatic hydrocarbon (n-hexane, n-heptane), aromatic hydrocarbon (benzene, toluene, ethylbenzene, n-propylbenzene), cyclohexane, thiophene, water, and 1-alcohol (1-ethanol, 1-butanol, 1-hexanol, 1-octanol, 1-decanol) have been determined using a dynamic method from room temperature to the boiling-point of the solvent at ambient pressure. N-hexylisoquinolinium thiocyanate, [HiQuin][SCN] has been synthesized from N-hexyl-isoquinolinium bromide as a substrate. Specific basic characterization of the new compound including NMR spectra, elementary analysis, and water content have been done. The density and viscosity of pure ionic liquid were determined over a wide temperature range from 298.15 to 348.15 K. The mutual immiscibility with an upper critical solution temperature (UCST) for the binary systems {IL + aliphatic hydrocarbon, cyclohexane, or water} was detected. In the systems of {IL + aromatic hydrocarbon or thiophene} an immiscibility gap with a lower critical solution temperature (LCST) was observed. Complete miscibility in the liquid phase, over a whole range of ionic liquid mole fraction, was observed for the binary mixtures containing IL and an 1-alcohol. For the tested binary systems with immiscibility gap {IL + aliphatic hydrocarbon, aromatic hydrocarbon, cyclohexane, thiophene, or water}, the parameters of the LLE correlation have been derived using the NRTL equation. The basic thermal properties of the pure IL, that is, the glass-transition temperature as well as the heat capacity at the glass-transition temperature, have been measured using a differential scanning microcalorimetry technique (DSC). Decomposition of the IL was detected by simultaneous thermogravimetric/differential thermal analysis (TG/DTA) experiments. PMID:22424076

Królikowska, Marta; Karpi?ska, Monika; Zawadzki, Maciej



Reaction of pharmacological active tris-(2-hydroxyethyl)ammonium 4-chlorophenylsulfanylacetate with ZnCl2 or NiCl2: first conversion of a protic ionic liquid into metallated ionic liquid.  


The reaction of pharmacological active protic ionic liquid tris-(2-hydroxyethyl)ammonium 4-chlorophenylsulfanylacetate H+N(CH2CH2OH)3 ? (-OOCCH2SC6H4Cl-4) (1) with zinc or nickel chloride in a ratio of 2:1 affords stable at room temperature powder-like adducts [H+N(CH2CH2OH)3]2 ? [M(OOCCH2SC6H4Cl-4)2Cl2]2-, M = Zn (2), Ni (3). By recrystallization from aqueous alcohol compound 2 unexpectedly gives Zn(OOCCH2SC6H4Cl-4)2 ? 2H2O (4). Unlike 2, compound 3 gives crystals [N(CH2CH2OH)3]2Ni2+?·?[-OOCCH2SC6H4Cl-4]2 (5), which have a structure of metallated ionic liquid. The structure of 5 has been proved by X-ray diffraction analysis. It is the first example of the conversion of a protic ionic liquid into potentially biological active metallated ionic liquid (1???3???5). PMID:23421876

Mirskova, Anna N; Adamovich, Sergey N; Mirskov, Rudolf G; Schilde, Uwe



Biphasic liquid mixtures of ionic liquids and polyethylene glycols.  


We have found that 1-alkyl-3-methylimidazolium chloride ionic liquids (ILs) can form immiscible liquid mixtures with some polyethylene glycols (PEGs). Binary mixtures of 1-ethyl-3-methylimidazolium chloride with PEG of molecular weight 1500, 2000, or 3400 g mol(-1), or of 1-butyl-3-methylimidazolium chloride with PEG of molecular weight 2000 or 3400 g mol(-1), have been found to give rise to entirely liquid, stable biphasic systems over a significant temperature range (from 333.15 K to 413.15 K), while mixtures of 1-ethyl-3-methylimidazolium chloride with PEG-1000 and 1-butyl-3-methylimidazolium chloride with PEG-1000 and PEG-1500 are miscible. The mutual immiscibility of the IL and the PEG increases as the temperature increases. The evolution of the composition of the phases in equilibrium with the molecular weight of the PEG, or with the variation of the length of the alkyl substituent chain of the imidazolium cation of the IL, has been explored. The trends observed are explained through the complexity of interactions present within the binary system. A thermodynamic analysis of the liquid-liquid equilibrium data indicates negative values for the change of enthalpy and entropy of mixing. The potential application of these biphasic, entirely liquid systems, with low volatility and good solvation properties, for the dissolution and separation of cellulose and lignin at elevated temperature has been preliminarily explored, although only modest results have been achieved to date. PMID:19924326

Rodríguez, Héctor; Francisco, María; Rahman, Mustafizur; Sun, Ning; Rogers, Robin D



Photoluminescent and gas-sensing properties of ZnO nanowires prepared by an ionic liquid assisted vapor transfer approach  

NASA Astrophysics Data System (ADS)

In this work, the ionic liquid assisted technique was used to control the growth characteristic of ZnO nanowires (NWs). The major change after adding ionic liquid into the growth system was the change in NW growth orientation, which was shifted from polar c- to non-polar a-orientation. Room temperature photoluminescence demonstrates a big reduction of the green luminescence which implies an annihilation of deep level emission. We propose two possible mechanisms responsible for the reduction of the green emission: The first mechanism is the passivation of ZnO NWs surface by fractions of ionic liquid employed for the growth, which further reduces the green emission. The second mechanism is the reduction of the defect density by changing the growth orientation. By using a semi-empirical Austin Model 1 method, the formation energy of oxygen vacancies in c- and a-oriented ZnO NWs has been simulated and compared. Accordingly, the gas-sensor constructed from ionic liquid assisted ZnO nanowires does not response when exposed to CO. This inert sensitivity is caused by the suppressed adsorption of CO molecules due to the presence of the passivation layer. The study presented here provides a new insight of how the recombination appears at the surface of ZnO NWs.

Subannajui, Kittitat; Wongchoosuk, Chatchawal; Ramgir, Niranjan; Wang, Chunyu; Yang, Yang; Hartel, Andreas; Cimalla, Volker; Zacharias, Margit



Soft ionization of thermally evaporated hypergolic ionic liquid aerosols.  


Isolated ion pairs of a conventional ionic liquid, 1-Ethyl-3-Methyl-Imidazolium Bis(trifluoromethylsulfonyl)imide ([Emim(+)][Tf(2)N(-)]), and a reactive hypergolic ionic liquid, 1-Butyl-3-Methyl-Imidazolium Dicyanamide ([Bmim(+)][Dca(-)]), are generated by vaporizing ionic liquid submicrometer aerosol particles for the first time; the vaporized species are investigated by dissociative ionization with tunable vacuum ultraviolet (VUV) light, exhibiting clear intact cations, Emim(+) and Bmim(+), presumably originating from intact ion pairs. Mass spectra of ion pair vapor from an effusive source of the hypergolic ionic liquid show substantial reactive decomposition due to the internal energy of the molecules emanating from the source. Photoionization efficiency curves in the near threshold ionization region of isolated ion pairs of [Emim(+)][Tf(2)N(-)] ionic liquid vapor are compared for an aerosol source and an effusive source, revealing changes in the appearance energy due to the amount of internal energy in the ion pairs. The aerosol source has a shift to higher threshold energy (?0.3 eV), attributed to reduced internal energy of the isolated ion pairs. The method of ionic liquid submicrometer aerosol particle vaporization, for reactive ionic liquids such as hypergolic species, is a convenient, thermally "cooler" source of isolated intact ion pairs in the gas phase compared to effusive sources. PMID:21506546

Koh, Christine J; Liu, Chen-Lin; Harmon, Christopher W; Strasser, Daniel; Golan, Amir; Kostko, Oleg; Chambreau, Steven D; Vaghjiani, Ghanshyam L; Leone, Stephen R



Topological Insulators at Room Temperature  

SciTech Connect

Topological insulators are new states of quantum matter with surface states protected by the time-reversal symmetry. In this work, we perform first-principle electronic structure calculations for Sb{sub 2}Te{sub 3}, Sb{sub 2}Se{sub 3}, Bi{sub 2}Te{sub 3} and Bi{sub 2}Se{sub 3} crystals. Our calculations predict that Sb{sub 2}Te{sub 3}, Bi{sub 2}T e{sub 3} and Bi{sub 2}Se{sub 3} are topological insulators, while Sb{sub 2}Se{sub 3} is not. In particular, Bi{sub 2}Se{sub 3} has a topologically non-trivial energy gap of 0.3eV , suitable for room temperature applications. We present a simple and unified continuum model which captures the salient topological features of this class of materials. These topological insulators have robust surface states consisting of a single Dirac cone at the {Lambda} point.

Zhang, Haijun; /Beijing, Inst. Phys.; Liu, Chao-Xing; /Tsinghua U., Beijing; Qi, Xiao-Liang; /Stanford U., Phys. Dept.; Dai, Xi; Fang, Zhong; /Beijing, Inst. Phys.; Zhang, Shou-Cheng; /Stanford U., Phys. Dept.



Silver halide fiber-based evanescent-wave liquid droplet sensing with thermoelectrically cooled room temperature mid-infrared quantum cascade lasers  

Microsoft Academic Search

Quantum cascade lasers coupled directly to unclad silver halide fibers were used to assemble mid-infrared fiber-optics evanescent-wave sensors suitable to measure the chemical composition of simple liquid droplets. Quantum cascade lasers can be designed to emit across a wide range of mid-infrared wavelengths by tailoring the quantum-well structure, and the wavelength can be fine tuned by a thermoelectric cooler. Here,

Jian Z. Chen; Zhijun Liu; Claire F. Gmachl; Deborah L. Sivco



Production of bioactive cellulose films reconstituted from ionic liquids.  


A new method for introducing enzymes into cellulosic matrixes which can be formed into membranes, films, or beads has been developed using a cellulose-in-ionic-liquid dissolution and regeneration process. Initial results on the formation of thin cellulose films incorporating dispersed laccase indicate that active enzyme-encapsulated films can be prepared using this methodology and that precoating the enzyme with a second, hydrophobic ionic liquid prior to dispersion in the cellulose/ionic liquid solution can provide an increase in enzyme activity relative to that of untreated films, presumably by providing a stabilizing microenvironment for the enzyme. PMID:15244454

Turner, Megan B; Spear, Scott K; Holbrey, John D; Rogers, Robin D



On the origin of ionicity in ionic liquids. Ion pairing versus charge transfer.  


In this paper we show by using static DFT calculations and classical molecular dynamics simulations that the charge transfer between ionic liquid ions plays a major role in the observed discrepancies between the overall mobility of the ions and the observed conductivities of the corresponding ionic liquids, while it also directly suppresses the association of oppositely charged ions, thus the ion pairing. Accordingly, in electrochemical applications of these materials it is important to consider this reduction of the total charges on the ions, which can greatly affect the performance of the given process or device in which the ionic liquid is used. By slightly shifting from the salt-like to a molecular liquid-like system via the decreased charges, the charge transfer also fluidizes the ionic liquid. We believe that this vital information on the molecular level structure of ionic liquids offers a better understanding of these materials, and allows us to improve the a priori design of ionic liquids for any given purpose. PMID:25012230

Hollóczki, Oldamur; Malberg, Friedrich; Welton, Tom; Kirchner, Barbara



Ionogels, ionic liquid based hybrid materials.  


The current interest in ionic liquids (ILs) is motivated by some unique properties, such as negligible vapour pressure, thermal stability and non-flammability, combined with high ionic conductivity and wide electrochemical stability window. However, for material applications, there is a challenging need for immobilizing ILs in solid devices, while keeping their specific properties. In this critical review, ionogels are presented as a new class of hybrid materials, in which the properties of the IL are hybridized with those of another component, which may be organic (low molecular weight gelator, (bio)polymer), inorganic (e.g. carbon nanotubes, silica etc.) or hybrid organic-inorganic (e.g. polymer and inorganic fillers). Actually, ILs act as structuring media during the formation of inorganic ionogels, their intrinsic organization and physicochemical properties influencing the building of the solid host network. Conversely, some effects of confinement can modify some properties of the guest IL, even though liquid-like dynamics and ion mobility are preserved. Ionogels, which keep the main properties of ILs except outflow, while allowing easy shaping, considerably enlarge the array of applications of ILs. Thus, they form a promising family of solid electrolyte membranes, which gives access to all-solid devices, a topical industrial challenge in domains such as lithium batteries, fuel cells and dye-sensitized solar cells. Replacing conventional media, organic solvents in lithium batteries or water in proton-exchange-membrane fuel cells (PEMFC), by low-vapour-pressure and non flammable ILs presents major advantages such as improved safety and a higher operating temperature range. Implementation of ILs in separation techniques, where they benefit from huge advantages as well, relies again on the development of supported IL membranes such as ionogels. Moreover, functionalization of ionogels can be achieved both by incorporation of organic functions in the solid matrix, and by encapsulation of molecular species (from metal complexes to enzymes) in the immobilized IL phase, which opens new routes for designing advanced materials, especially (bio)catalytic membranes, sensors and drug release systems (194 references). PMID:21180731

Le Bideau, Jean; Viau, Lydie; Vioux, André



FEATURE ARTICLE Room Temperature Ballistic Conduction in Carbon Nanotubes  

E-print Network

nanotubes are shown to be ballistic conductors at room temperature, with mean free paths of the order that contact with a liquid metal surface. These experiments follow and extend the original experiments by Frank that the multiwalled carbon nanotubes (MWNTs) are one-dimensional conductors, that electronic transport occurs

Wang, Zhong L.


Operation of Silicon, Diamond and liquid Helium Detectors in the range of Room Temperature to 1.9 K and after an Irradiation Dose of several Mega Gray  

E-print Network

At the triplet magnets, close to the interaction regions of the Large Hadron Collider (LHC), the current Beam Loss Monitoring (BLM) system is sensitive to the debris from the collision points. For future beams, with higher energy and intensity the expected increase in luminosity implicate an increase of the debris from interaction products covering the quench-provoking beam losses from the primary proton beams. The investigated option is to locate the detectors as close as possible to the superconducting coil, where the signal ratio of both is optimal. Therefore the detectors have to be located inside the cold mass of the superconducting magnets in superfluid helium at 1.9 Kelvin. Past measurements have shown that a liquid helium ionisation chamber, diamond and silicon detectors are promising candidates for cryogenic beam loss monitors. The carrier parameter, drift velocity, and the leakage current changes will be shown as a function of temperature. New high irradiation test beam measurements at room temperat...

Kurfuerst, C; Dehning, B; Eisel, T; Sapinski, M; Eremin, V



Encapsulation Method of Glucose Oxidase Solution with Ionic Liquid Solvent and Direct Parylene Deposition  

NASA Astrophysics Data System (ADS)

We developed new encapsulation method of glucose oxidase solution with ionic liquid solvent and direct Parylene deposition for the application to MEMS glucose sensors. Glucose oxidase has been immobilized in gel or polymer on MEMS sensors, but its weak mechanical property has been remained to be solved. Then, its encapsulation has been demanded, but high-temperature MEMS bonding process (>150 °C) for packaging the solution is destructive to glucose oxidase which is denatured over 50 °C. To solve these problems, we encapsulated the glucose oxidase-ionic liquid solution with room-temperature packaging (25 °C) of direct Parylene deposition process. The glucose oxidase solution array with the area of 1 × 3 mm2 (approximately 1 ?l) was patterned on the hydrophilic-hydrophobic surface modification on the MEMS electrochemical electrodes in the use of the wetting phenomenon of the solution and, then, packaged by the chemical vapor deposition of 1.5 ?m Parylene. Parylene packages could be opened by pushing when used. The opened glucose oxidase solution reacted to 150 mM glucose solution, revealing the electrochemical potential of 150 mV. The sensitivity of our sensor ranged from 1 to 100 mM, which is the glucose concentration in the blood of the diabetic patients. Therefore, proposed encapsulation method exhibits the potential application to glucose sensor packages for diabetic patients.

Takamatsu, Seiichi; Takano, Hisanori; Binh-Khiem, Nguyen; Iwase, Eiji; Matsumoto, Kiyoshi; Shimoyama, Isao


Ultrafast and ultraslow proton transfer of pyranine in an ionic liquid microemulsion.  


Effect of a room temperature ionic liquid (RTIL) and water on the ultrafast excited state proton transfer (ESPT) of pyranine (8-hydroxypyrene-1,3,6-trisulfonate, HPTS) inside a microemulsion is studied by femtosecond up-conversion. The microemulsion consists of the surfactant, triton X-100 (TX-100) in benzene (bz) and contains the RTIL, 1-pentyl-3-methyl-imidazolium tetrafluoroborate ([pmim] [BF(4)]) as the polar phase. In the absence of water, HPTS undergoes ultrafast ESPT inside the RTIL microemulsion (RTIL/TX-100/bz) and the deprotonated form (RO(-)) exhibits three rise components of 0.3, 14, and 375 ps. It is proposed that in the RTIL microemulsion, HPTS binds to the TX-100 at the interface region and participates in ultrafast ESPT to the oxygen atoms of TX-100. On addition of water an additional slow rise of 2150 ps is observed. Similar long rise component is also observed in water/TX-100/benzene reverse micelle (in the absence of [pmim] [BF(4)]). It is suggested that the added water molecules preferentially concentrate (trapped) around the palisade layer of the RTIL microemulsion. The trapped water molecules remain far from the HPTS both in the presence and absence of ionic liquid and gives rise to the slow component (2150 ps) of ESPT. Replacement of H(2)O by D(2)O causes an increase in the time constant of the ultraslow rise to 2350 ps. PMID:20499977

Sen Mojumdar, Supratik; Mondal, Tridib; Das, Atanu Kumar; Dey, Shantanu; Bhattacharyya, Kankan



Structure of ionic liquids of 1-alkyl-3-methylimidazolium cations: A systematic computer simulation study  

NASA Astrophysics Data System (ADS)

Molecular dynamics simulations of room temperature molten salts (ionic liquids) containing imidazolium cations have been performed. Ten different systems were simulated at 323 K by using united atom force fields, in which the anion size (F-, Cl-, Br-, and PF6-) and the length of the alkyl chain of 1-alkyl-3-methylimidazolium cations (1-methyl-, 1-ethyl-, 1-butyl-, and 1-octyl-) were systematically varied. It is shown that the resulting equilibrium structures account for the observed features of experimental static structure factors when available. A detailed analysis of the simultaneous effect of changing the anion and the alkyl chain on the preferential location of nearest-neighbor anions around the cations is provided. It is shown that regions above and below the imidazolium ring are the preferential ones in case of large anions. By increasing the length of the alkyl chain, nearest-neighbor anions are pushed away from the volume occupied by the flexible alkyl chain. Partial structure factors of 1-butyl- and 1-octyl- derivatives display a peak at a wave vector smaller than the main peak, indicating the occurrence of an intermediate range order in these ionic liquids due to the presence of long alkyl chains.

Urahata, Sérgio M.; Ribeiro, Mauro C. C.



Ionic liquids based on polynitrile anions: hydrophobicity, low proton affinity, and high radiolytic resistance combined.  


Ionic liquids (IL) are being considered as replacements for molecular diluents in spent nuclear fuel reprocessing. This development is hampered by the dearth of constituent anions that combine high hydrophobicity, low metal cation and proton affinity, and radiation resistance. We demonstrate that polynitrile anions have the potential to meet these challenges. Unlike the great majority of organic anions, such polynitrile anions are resistant to oxidative fragmentation during radiolysis, yielding stable N- and C-centered radicals. Moreover, their radical dianions (generated by reduction of the anions) generally undergo protonation in preference to elimination of the cyanide. This is in contrast to fluorinated anions (another large class of anions with low proton affinity), for which radiation-induced release of fluoride is a common occurrence. The "weak spot" of the polynitrile anions appears to be their excited-state dissociation, but at least one of these anions, 1,1,2,3,3-pentacyanopropenide, is shown to resist fragmentation in room temperature radiolysis. We suggest beginning the exploration of ionic liquids based on such polynitrile anions. PMID:23697390

Shkrob, Ilya A; Marin, Timothy W; Wishart, James F



The Influence of Silica Nanoparticles on Ionic Liquid Behavior: A Clear Difference between Adsorption and Confinement  

PubMed Central

The phase behaviors of ionic liquids (ILs) confined in nanospace and adsorbed on outer surface of nanoparticles are expected to be different from those of the bulk. Anomalous phase behaviors of room temperature ionic liquid tributylhexadecylphosphonium bromide (P44416Br) confined in ordered mesoporous silica nanoparticles with average pore size 3.7 nm and adsorbed on outer surface of the same silica nanoparticles were reported. It was revealed that the melting points (Tm) of confined and adsorbed ILs depressed significantly in comparison with the bulk one. The Tm depressions for confined and adsorbed ILs are 8 °C and 14 °C, respectively. For comparison with the phase behavior of confined P44416Br, 1-butyl-3-methylimidazolium bromide (BmimBr) was entrapped within silica nanopores, we observed an enhancement of 50 °C in Tm under otherwise similar conditions. The XRD analysis indicates the formation of crystalline-like phase under confinement, in contrast to the amorphous phase in adsorbed IL. It was confirmed that the behavior of IL has clear difference. Moreover, the complex ?-? stacking and H-bonding do not exist in the newly proposed phosphonium-based IL in comparison with the widely studied imidazolium-based IL. The opposite change in melting point of P44416Br@SiO2 and BmimBr@SiO2 indicates that the cationic species plays an important role in the variation of melting point. PMID:24145752

Wang, Yaxing; Li, Cheng; Guo, Xiaojing; Wu, Guozhong



A monolithic functional film of nanotubes/cellulose/ionic liquid for high performance supercapacitors  

NASA Astrophysics Data System (ADS)

A novel monolithic, pre-fabricated, fully functional film made of a nanostructured free-standing layer is presented for a new and competitive class of easy-to-assemble flexible supercapacitors whose design is in-between the all solid state and the traditional liquid electrolyte. The film is made of two vertically aligned multi-walled carbon nanotube (VANT) electrodes that store ions, embedded-in, and monolithically interspaced by a solution of microcrystalline cellulose in a room temperature ionic liquid (RTIL) electrolyte (1-ethyl-3-methylimidazolium acetate-EMIM Ac). The fine tuning of VANTs length and electrolyte/cellulose amount leads, in a sole and continuous block, to ions storage and physical separation between the electrodes without the need of the additional separator layer that is typically used in supercapacitors. Thus, physical discontinuities that can induce disturbances to ions mobility, are fully eliminated significantly reducing the equivalent series resistance and increasing the knee frequency, hence outclassing the best supercapacitors based on VANTs and non-aqueous electrolytes. The excellent electrochemical response can also be addressed to the chosen electrolyte that, not only has the advantage of leading to a significantly simpler and more affordable fabrication procedure, but has higher ionic conductivity, lower viscosity and higher ions mobility than other electrolytes capable of dissolving cellulose.

Basiricò, Lucia; Lanzara, Giulia



Borohydride ionic liquids and borane/ionic-liquid solutions as hypergolic fuels with superior low ignition-delay times.  


In propellant systems, fuels of choice continue to be hydrazine and its derivatives, even though they comprise a class of acutely carcinogenic and toxic substances which exhibit rather high vapor pressures and require expensive handling procedures and costly safety precautions. Hypergolic ionic liquids tend to have low volatility and high thermal and chemical stability, and often exhibit wide liquid ranges, which could allow the use of these substances as bipropellant fuels under a variety of conditions. A new family of borohydride ionic liquids and borane-ionic-liquid solutions is described which meets nearly all of the desired important criteria for well-performing fuels. They exhibit ignition-delay times that are superior to that of any known hypergolic ionic liquid and may thus be legitimate replacements for hydrazine and its derivatives. PMID:24604814

Li, Songqing; Gao, Haixiang; Shreeve, Jean'ne M



Double Layer in Ionic Liquids: Overscreening versus Crowding  

E-print Network

We develop a simple Landau-Ginzburg-type continuum theory of solvent-free ionic liquids and use it to predict the structure of the electrical double layer. The model captures overscreening from short-range correlations, ...

Bazant, Martin Z.


Dispenser Printed Zinc Microbattery with an Ionic Liquid Gel Electrolyte  

E-print Network

zinc through an ionic liquid electrolyte is not uniform, but rather mossy.mossy growth is visible especially at the interfaces between the electrolyte and zincmossy growth is visible especially at the interfaces between the electrolyte and zinc

Ho, Christine Chihfan



Ionic liquid electrolyte porphyrin dye sensitised solar cells.  


Ionic liquid electrolytes based on a number of imidazolium, quaternary ammonium and phosphonium cations have been developed for porphyrin dye sensitised solar cells yielding efficiencies of up to 5.2% at 0.68 Sun. PMID:20424755

Armel, Vanessa; Pringle, Jennifer M; Forsyth, Maria; Macfarlane, Douglas R; Officer, David L; Wagner, Pawel



Superacid cyclization of certain aliphatic sesquiterpene derivatives in ionic liquids  

Microsoft Academic Search

Superacid cyclization was demonstrated for the first time to be successful in those ionic liquids with functional groups that\\u000a are stable in the reaction medium using aliphatic sesquiterpene derivatives as examples.

M. Grin’ko; V. Kul’chitskii; N. Ungur; P. F. Vlad



Shear and Extensional Rheology of Cellulose/Ionic Liquid Solutions  

E-print Network

In this study, we characterize the shear and extensional rheology of dilute to semidilute solutions of cellulose in the ionic liquid 1-ethyl-3-methylimidazolium acetate (EMIAc). In steady shear flow, the semidilute solutions ...

Haward, Simon J.


Hypergolic Ionic Liquids DOI: 10.1002/anie.201101247  

E-print Network

to conventional fossil fuels. Commonly used hypergolic fuels include hydrazine and its methylated derivatives costs and safety require- ments associated with handling hydrazine.[2] Ionic liquids (ILs)[3] have

Zare, Richard N.


Ionic Liquid Co-catalyzed Artificial Photosynthesis of CO  

NASA Astrophysics Data System (ADS)

The conversion of CO2 to chemical feedstocks is of great importance, which yet requires the activation of thermodynamically-stable CO2 by metal catalysts or metalloenzymes. Recently, the development of metal-free organocatalysts for use in CO2 activation under ambient conditions has opened new avenues for carbon fixation chemistry. Here, we report the capture and activation of CO2 by ionic liquids and coupling to photoredox catalysis to synthesize CO. The chemical nature of anions and the organic functional groups on the imidazolium cations of ionic liquids, together with reaction medium have been demonstrated to have remarkable effects on the activation and reduction of CO2. Considering almost unlimited structural variations of ionic liquids by a flexible combination of cations and anions, this photochemical pathway provides unique opportunities for carbon fixation by rationally-designed chemical systems via linking ionic liquid based materials with chromorphoric molecules in tackling the great challenges of artificial photosynthesis.

Lin, Jinliang; Ding, Zhengxin; Hou, Yidong; Wang, Xinchen



Ionic-liquid-supported synthesis: a novel liquid-phase strategy for organic synthesis.  


Soluble ionic liquids have recently been used as supports for catalyst/reagent immobilization and synthesis in homogeneous solution phase. The wide range of ionic liquid supports available makes their use as supports compatible with most common chemistries. The solubility properties of these ionic liquid supports can be tuned by the variation of cations and anions to make them phase separate from less polar organic solvents and aqueous media. The ionic-liquid-supported species can therefore be purified from the reaction mixture by simple washings. Ionic-liquid-supported catalysts and reagents have been prepared and used, and they are easily recovered and reused. Parallel and combinatorial libraries of small molecules have been synthesized. Ionic-liquid-supported synthesis (ILSS) has been applied to the preparation of oligopeptides and oligosaccharides. The comparison of ILSS with solid-phase synthesis, soluble-polymer-supported synthesis, and fluorous phase synthesis has been highlighted where applicable. PMID:17176028

Miao, Weishi; Chan, Tak Hang



The Pressure–Viscosity Coefficient of Several Ionic Liquids  

Microsoft Academic Search

The choice of cation and anion in an ionic liquid (IL) as well as the design of ion side chains determine the fundamental\\u000a properties of ILs, which permits creating tailor-made lubricants and lubricant additives. So, the study of the influence\\u000a of molecular structure on thermophysical properties of ionic liquids is essential for their use in lubrication. Recent results\\u000a from the

A. S. Pensado; M. J. P. Comuñas; J. Fernández



Ionic liquid propellants: future fuels for space propulsion.  


Use of green propellants is a trend for future space propulsion. Hypergolic ionic liquid propellants, which are environmentally-benign while exhibiting energetic performances comparable to hydrazine, have shown great potential to meet the requirements of developing nontoxic high-performance propellant formulations for space propulsion applications. This Concept article presents a review of recent advances in the field of ionic liquid propellants. PMID:24136866

Zhang, Qinghua; Shreeve, Jean'ne M



Diphosphonium Ionic Liquids as Broad Spectrum Antimicrobial Agents  

PubMed Central

Purpose One of the most disturbing trends in recent years is the growth of resistant strains of bacteria with the simultaneous dearth of new antimicrobial agents. Thus, new antimicrobial agents for use on the ocular surface are needed. Methods We synthesized a variety of ionic liquid compounds, which possess two positively charged phosphonium groups separated by ten methylene units in a “bola” type configuration. We tested these compounds for antimicrobial activity versus a variety of ocular pathogens, as well as their cytoxicity in vitro in a corneal cell line and in vivo in mice. Results The ionic liquid Di-Hex C10 demonstrated broad in vitro antimicrobial activity at the low micromolar concentrations versus Gram-negative and Gram-positive organisms, including methicillin-resistant Staphylococcus aureus strains, as well as ocular fungal pathogens. Treatment with Di-Hex C10 resulted in bacterial killing in as little as 15 minutes in vitro. Di-Hex C10 showed little cytotoxicity at 1 ?M versus a corneal epithelial cell line or at 10 ?M in a mouse corneal wound model. We also show that this bis-phosphonium ionic liquid structure is key, as a comparable mono phosphonium ionic liquid is cytotoxic to both bacteria and corneal epithelial cells. Conclusions Here we report the first use of dicationic bis-phosphonium ionic liquids as antimicrobial agents. Our data suggest that diphosphonium ionic liquids may represent a new class of broad-spectrum antimicrobial agents for use on the ocular surface. PMID:22236790

O’Toole, George A.; Wathier, Michel; Zegans, Michael E.; Shanks, Robert M.Q.; Kowalski, Regis; Grinstaff, Mark W.



On the components of the dielectric constants of ionic liquids: ionic polarization?  


According to dielectric spectroscopy measurements, ionic liquids (ILs) have rather modest dielectric constants that reflect contributions from distortion and electronic polarization caused by the molecular polarizability as well as the orientation polarization caused by the permanent dipole moment of the ions. To understand the relative importance of these various contributions, the electronic polarizabilities of 27 routinely used ionic liquid ions of different symmetry and size were calculated using ab initio-based methods such as HF and MP2. Using the Clausius-Mossotti equation, these polarizabilities were then used to obtain the electronic polarization contribution (epsilon(op)) to the dielectric constants of six ionic liquids, [C(2)mim][BF(4)], [C(2)mpyr][N(CN)(2)], [C(2)mim][CF(3)SO(3)], [EtNH(3)][NO(3)], [C(2)mim][NTf(2)] and [C(2)mim][EtSO(4)]. Theoretical epsilon(op) values were compared to experimental refractive indices of these ionic liquids as well as to those of traditional molecular solvents such as water, tetrahydrofuran (THF), dimethylsulfoxide (DMSO) and formamide. The dipole moments of the ions were also calculated, and from these it is shown that the molecular reorientation component of the dielectric constants of the ionic liquids consisting of ions with small or negligible dipole moments is quite small. Thus it is concluded that a contribution from a form of "ionic polarization" must be present. PMID:19325978

Izgorodina, Ekaterina I; Forsyth, Maria; Macfarlane, Douglas R



Imidazolium 2-substituted 4,5-dicyanoimidazolate ionic liquids: synthesis, crystal structures and structure-thermal property relationships.  


Thirty six novel ionic liquids (ILs) with 1-butyl-3-methylimidazolium and 3-methyl-1-octylimidazolium cations paired with 2-substitited 4,5-dicyanoimidazolate anions (substituent at C2 = chloro, bromo, methoxy, vinyl, amino, methyl, ethyl, propyl, isopropyl, butyl, pentyl, hexyl, heptyl, octyl, nonyl, decyl, undecyl and phenyl) have been synthesized and characterized by using differential scanning calorimetry (DSC), thermogravimetric analysis (TGA) and single-crystal X-ray crystallography. The effects of cation and anion type and structure on the thermal properties of the resulting ionic liquids, including several room temperature ionic liquids (RTILs) are examined and discussed. ILs exhibited large liquid and crystallization ranges and formed glasses on cooling with glass transition temperatures in the range of -22 to -68?°C. The effects of alkyl substituents of the imidazolate anion reflected the crystallization, melting points and thermal decomposition of the ILs. The Coulombic packing force, van der Waals forces and size of the anions can be considered for altering the thermal transitions. Three crystal structures of the ILs were determined and the effects of changes to the cations and anions on the packing of the structure were investigated. PMID:24888334

Mondal, Suvendu Sekhar; Müller, Holger; Junginger, Matthias; Kelling, Alexandra; Schilde, Uwe; Strehmel, Veronika; Holdt, Hans-Jürgen



Ionic liquid analogues formed from hydrated metal salts.  


A dark green, viscous liquid can be formed by mixing choline chloride with chromium(III) chloride hexahydrate and the physical properties are characteristic of an ionic liquid. The eutectic composition is found to be 1:2 choline chloride/chromium chloride. The viscosity and conductivity are measured as a function of temperature and composition and explained in terms of the ion size and liquid void volume. The electrochemical response of the ionic liquid is also characterised and it is shown that chromium can be electrodeposited efficiently to yield a crack-free deposit. This approach could circumvent the use of chromic acid for chromium electroplating, which would be a major environmental benefit. This method of using hydrated metal salts to form ionic liquids is shown to be valid for a variety of other salt mixtures with choline chloride. PMID:15281161

Abbott, Andrew P; Capper, Glen; Davies, David L; Rasheed, Raymond K



Method and apparatus using an active ionic liquid for algae biofuel harvest and extraction  


The invention relates to use of an active ionic liquid to dissolve algae cell walls. The ionic liquid is used to, in an energy efficient manner, dissolve and/or lyse an algae cell walls, which releases algae constituents used in the creation of energy, fuel, and/or cosmetic components. The ionic liquids include ionic salts having multiple charge centers, low, very low, and ultra low melting point ionic liquids, and combinations of ionic liquids. An algae treatment system is described, which processes wet algae in a lysing reactor, separates out algae constituent products, and optionally recovers the ionic liquid in an energy efficient manner.

Salvo, Roberto Di; Reich, Alton; Dykes, Jr., H. Waite H.; Teixeira, Rodrigo



Liquid–liquid extraction of actinides, lanthanides, and fission products by use of ionic liquids: from discovery to understanding  

Microsoft Academic Search

Liquid–liquid extraction of actinides and lanthanides by use of ionic liquids is reviewed, considering, first, phenomenological\\u000a aspects, then looking more deeply at the various mechanisms. Future trends in this developing field are presented.

Isabelle Billard; Ali Ouadi; Clotilde Gaillard



Transport coefficients, Raman spectroscopy, and computer simulation of lithium salt solutions in an ionic liquid.  


Lithium salt solutions of Li(CF3SO2)2N, LiTFSI, in a room-temperature ionic liquid (RTIL), 1-butyl-2,3-dimethyl-imidazolium cation, BMMI, and the (CF3SO2)2N(-), bis(trifluoromethanesulfonyl)imide anion, [BMMI][TFSI], were prepared in different concentrations. Thermal properties, density, viscosity, ionic conductivity, and self-diffusion coefficients were determined at different temperatures for pure [BMMI][TFSI] and the lithium solutions. Raman spectroscopy measurements and computer simulations were also carried out in order to understand the microscopic origin of the observed changes in transport coefficients. Slopes of Walden plots for conductivity and fluidity, and the ratio between the actual conductivity and the Nernst-Einstein estimate for conductivity, decrease with increasing LiTFSI content. All of these studies indicated the formation of aggregates of different chemical nature, as it is corroborated by the Raman spectra. In addition, molecular dynamics (MD) simulations showed that the coordination of Li+ by oxygen atoms of TFSI anions changes with Li+ concentration producing a remarkable change of the RTIL structure with a concomitant reduction of diffusion coefficients of all species in the solutions. PMID:18220384

Monteiro, Marcelo J; Bazito, Fernanda F C; Siqueira, Leonardo J A; Ribeiro, Mauro C C; Torresi, Roberto M



A mean-field theory on the differential capacitance of asymmetric ionic liquid electrolytes  

NASA Astrophysics Data System (ADS)

The size of ions significantly influences the electric double layer structure of room temperature ionic liquid (IL) electrolytes and their differential capacitance (Cd). In this study, we extended the mean-field theory (MFT) developed independently by Kornyshev (2007J. Phys. Chem. B 111 5545-57) and Kilic, Bazant, and Ajdari (2007 Phys. Rev. E 75 021502) (the KKBA MFT) to take into account the asymmetric 1:1 IL electrolytes by introducing an additional parameter ? for the anion/cation volume ratio, besides the ionic compressibility ? in the KKBA MFT. The MFT of asymmetric ions becomes KKBA MFT upon ? = 1, and further reduces to Gouy-Chapman theory in the ? ? 0 limit. The result of the extended MFT demonstrates that the asymmetric ILs give rise to an asymmetric Cd, with the higher peak in Cd occurring at positive polarization for the smaller anionic size. At high potential, Cd decays asymptotically toward KKBA MFT characterized by ? for the negative polarization, and characterized by ?? for the positive polarization, with inverse-square-root behavior. At low potential, around the potential of zero charge, the asymmetric ions cause a higher Cd, which exceeds that of Gouy-Chapman theory.

Han, Yining; Huang, Shanghui; Yan, Tianying



Raidiation-Induced Fragmentation of Diamide Extraction Agents in Ionic Liquid Diluents  

SciTech Connect

N,N,N',N'-Tetraalkyldiglycolamides are extracting agents that are used for liquid-liquid extraction of trivalent metal ions in wet processing of spent nuclear fuel. This application places such agents in contact with the decaying radionuclides, causing radiolysis of the agent in the organic diluent. Recent research seeks to replace common molecular diluents (such as n-dodecane) with hydrophobic room-temperature ionic liquids (ILs), which have superior solvation properties. In alkane diluents, rapid radiolytic deterioration of diglycolamide agents can be inhibited by addition of an aromatic cosolvent that scavenges highly reactive alkane radical cations before these oxidize the extracting agent. Do aromatic ILs exhibit a similar radioprotective effect? To answer this question, we used electron paramagnetic resonance spectroscopy to study the fragmentation pathways in radiolysis of neat diglycolamides, their model compounds, and their solutions in the ILs. Our study indicates that aromatic ILs do not protect these types of solutes from extensive radiolytic damage. Previous research indicated a similar lack of protection for crown ethers, whereas the ILs readily protected di- and trialkyl phosphates (another large class of metal-extracting agents). Our analysis of these unanticipated failures suggests that new types of organic anions are required in order to formulate ILs capable of radioprotection for these classes of solutes. This study is a cautionary tale of the fallacy of analogical thinking when applied to an entirely new and insufficiently understood class of chemical materials.

Bell, Jason R [ORNL; Dai, Sheng [ORNL; Shkrob, Ilya A. [Argonne National Laboratory (ANL); Marin, Timothy W. [Argonne National Laboratory (ANL); Luo, Huimin [ORNL; Hatcher, Jasmine [Brookhaven National Laboratory (BNL); Rimmer, R. Dale [Brookhaven National Laboratory (BNL); Wishart, James F. [Brookhaven National Laboratory (BNL)



Conductivity of ionic liquid-derived polymers with internal gold nanoparticle conduits.  

SciTech Connect

The transport properties of self-supporting Au nanoparticle-ionic liquid-derived polymer composites were characterized. Topographic AFM images confirm the perforated lamellar composite architecture determined by small-angle X-ray scattering (SAXS) and further show that the in situ synthesized Au nanoparticles are localized within the hydrophilic (water) domains of the structure. At low Au nanoparticle content, the images reveal incomplete packing of spherical particles (i.e., voids) within these columns. The confinement and organization of the Au nanoparticles within the hydrophilic columns give rise to a large manifold of optical resonances in the near-IR region. The bulk composite conductivity, R{sub b}, was determined by ac electrochemical impedance spectroscopy (EIS) for samples prepared with increasing Au{sup 3+} content over a frequency range of 10 Hz to 1 MHz. A 100-fold increase was observed in the bulk conductivity at room temperature for composites prepared with the highest amount of Au{sup 3+} (1.58 {+-} 0.065 {micro}mol) versus the no Au composite, with the former reaching a value of 1.3 x 10{sup -4} S cm{sup -1} at 25 C. The temperature dependence of the conductivity recorded over this range was well-modeled by the Arrhenius equation. EIS studies on samples containing the highest Au nanoparticle content over a broader range of frequencies (2 x 10{sup -2} Hz to 5 x 10{sup 5} Hz) identified a low frequency component ascribed to electronic conduction. Electronic conduction due to aggregated Au nanoparticles was further confirmed by dc conductivity measurements. This work identifies a nanostructured composite that exhibits both ionic transport through the polymeric ionic liquid and electronic conduction from the organized encapsulated columns of Au nanoparticles.

Lee, S.; Cummins, M. D.; Willing, G. A.; Firestone, M. A.; Materials Science Division; Univ. of Louisville



Confused ionic liquid ions--a "liquification" and dosage strategy for pharmaceutically active salts.  


We present a strategy to expand the liquid and compositional ranges of ionic liquids, specifically pharmaceutically active ionic liquids, by simple mixing with a solid acid or base to form oligomeric ions. PMID:20449254

Bica, Katharina; Rogers, Robin D



Ionic Liquid Catalyzed Electrolyte for Electrochemical Polyaniline Supercapacitors  

NASA Astrophysics Data System (ADS)

The effect of different wt.% of ionic liquid "1,6-bis (trimethylammonium-1-yl) hexane tetrafluoroborate" in 0.5 M LiClO4+PC electrolyte on the supercapacitor properties of polyaniline (PANI) thin film are investigated. The PANI film is synthesized using electropolymerization of aniline in the presence of sulfuric acid. The electrochemical properties of the PANI thin film are studied by cyclic voltammetry, galvanostatic charge-discharge and electrochemical impedance spectroscopy (EIS) measurements. The optimum amount of the ionic liquid is found to be 2 wt.% which provides better ionic conductivity of the electrolyte. The highest specific capacitance of 259 F/g is obtained using the 2 wt.% electrolyte. This capacitance remains at up to 208 F/g (80% capacity retention) after 1000 charge-discharge cycles at a current density of 0.5 mA/g. The PANI film in the 2 wt.% ionic liquid catalyzed 0.5 M LiClO4+PC electrolyte shows small electrochemical resistance, better rate performance and higher cyclability. The increased ionic conductivity of the 2 wt.% ionic liquid catalyzed electrolyte causes a reduction in resistance at the electrode/electrolyte interface, which can be useful in electrochemically-preferred power devices for better applicability.

Inamdar, A. I.; Im, Hyunsik; Jung, Woong; Kim, Hyungsang; Kim, Byungchul; Yu, Kook-Hyun; Kim, Jin-Sang; Hwang, Sung-Min



Electrodeposition of Ge, Si and Si x Ge 1-x from an air- and water-stable ionic liquid.  


The electrodeposition of Ge, Si and, for the first time, of Si(x)Ge(1-x) from the air- and water-stable ionic liquid 1-butyl-1-methylpyrrolidinium bis(trifluoromethylsulfonyl)amide ([Py(1,4)]Tf(2)N) containing GeCl(4) and/or SiCl(4) as precursors is investigated by cyclic voltammetry and high-resolution scanning electron microscopy. GeCl(2) in [Py(1,4)]Tf(2)N is electrochemically prepared in a two-compartment cell to be used as Ge precursor instead of GeCl(4) in order to avoid the chemical attack of Ge(iv) on deposited Ge. Silicon, germanium and Si(x)Ge(1-x) can be deposited reproducibly and easily in this ionic liquid. Interestingly, the Si(x)Ge(1-x) deposit showed a strong colour change (from red to blue) at room temperature during electrodeposition, which is likely to be due to a quantum size effect. The observed colours are indicative of band gaps between at least 1.5 and 3.2 eV. The potential of ionic liquids in Si(x)Ge(1-x) electrodeposition is demonstrated. PMID:18665315

Al-Salman, R; El Abedin, S Zein; Endres, F



Physicochemical properties and toxicities of hydrophobicpiperidinium and pyrrolidinium ionic liquids  

SciTech Connect

Some properties are reported for hydrophobic ionic liquids (IL) containing 1-methyl-1-propyl pyrrolidinium [MPPyrro]{sup +}, 1-methyl-1-butyl pyrrolidinium [MBPyrro]{sup +}, 1-methyl-1-propyl piperidinium [MPPip]{sup +}, 1-methyl-1-butyl piperidinium [MBPip]{sup +}, 1-methyl-1-octylpyrrolidinium [MOPyrro]{sup +} and 1-methyl-1-octylpiperidinium [MOPip]{sup +} cations. These liquids provide new alternatives to pyridinium and imidazolium ILs. High thermal stability of an ionic liquid increases safety in applications like rechargeable lithium-ion batteries and other electrochemical devices. Thermal properties, ionic conductivities, viscosities, and mutual solubilities with water are reported. In addition, toxicities of selected ionic liquids have been measured using a human cancer cell-line. The ILs studied here are sparingly soluble in water but hygroscopic. We show some structure-property relationships that may help to design green solvents for specific applications. While ionic liquids are claimed to be environmentally-benign solvents, as yet few data have been published to support these claims.

Salminen, Justin; Papaiconomou, Nicolas; Kumar, R. Anand; Lee,Jong-Min; Kerr, John; Newman, John; Prausnitz, John M.



Ionic conductivity of imidazole-functionalized liquid crystal mesogens  

NASA Astrophysics Data System (ADS)

Imidazole has been investigated as a novel anhydrous proton conducting functional group that could enable higher temperature operation (> 120 ^oC) of polymer electrolyte fuel cells. Its amphoteric behavior can support Grotthuss-like proton transport; however molecular mobility and a high concentration of imidazole groups are needed to achieve high ionic conductivity. Our hypothesis is that liquid crystal ordering, particularly in layered smectic phase, can facilitate formation of 2D proton transport and promote proton conductivity. We have designed and synthesized two imidazole-terminated liquid crystal mesogens, and the ionic conductivities in the liquid crystalline and isotropic states have been measured. Here we report on synthesis and characterization of diacylhydrazine liquid crystals bearing imidazole terminal groups. The proton conductivity of products is compared to pure liquid imidazole and to liquid crystal mesogens without imidazole groups.

Roddecha, Supacharee; Anthamatten, Mitchell



A recyclable enzymatic biodiesel production process in ionic liquids.  


Immobilized Candida antarctica lipase B suspended in ionic liquids containing long alkyl-chain cations showed excellent synthetic activity and operational stability for biodiesel production. The interest of this process lies in the possibility of recycling the biocatalyst and the easy separation of the biodiesel from the reaction mixture. The ionic liquids used, 1-hexadecyl-3-methylimidazolium triflimide ([C(16)MIM][NTf(2)]) and 1-octadecyl-3-methylimidazolium triflimide ([C(18)MIM][NTf(2)]), produced homogeneous systems at the start of the reaction and, at the end of the same, formed a three-phase system, allowing the selective extraction of the products using straightforward separation techniques, and the recycling of both the ionic liquid and the enzyme. These are very important advantages which may be found useful in environmentally friendly production conditions. PMID:21392972

De Diego, Teresa; Manjón, Arturo; Lozano, Pedro; Iborra, José L



Electrochemical Creeping and Actuation of Polypyrrole in Ionic Liquid  

NASA Astrophysics Data System (ADS)

The electrochemical creeping and actuation of polypyrrole films operated in an ionic liquid are reported. The electrochemical deformation was initiated by the reduction and swelling of the films by 15-20% with soaking in ionic liquid. An electrochemical strain of 3% and a blocked stress of 1.7 MPa showing cation movement were obtained. The film showed creeping at tensile loads larger than 0.5 MPa. The electrochemical strain obtained in a mixed solution of an ionic liquid and propylene carbonate was 15% at the initial stage, showing anion movement together with swelling induced by soaking in solvents. However, the electrochemical strain became negligible after several electrochemical cycles, resulting from the loss of electrochemical activity and conductivity upon swelling.

Kaneto, Keiichi; Shinonome, Teruyuki; Tominaga, Kazuo; Takashima, Wataru



New room temperature molten salt solvent system: organic cation tetrachloroborates  

Microsoft Academic Search

In the past decade there has been considerable interest in AlClâ-containing molten salts. These metals provide novel media for fundamental studies and are also of interest in high-energy batteries and for catalytic applications. Relatively few molten salt systems are liquid at or below room temperature. The properties of these systems, mainly organic chloroaluminates, have been reviewed by Hussey, several other

Stephen D. Williams; J. P. Schoebrechts; J. C. Selkirk; G. Mamantov



Ferromagnetism of Zn 0.95Mn 0.05O controlled by concentration of zinc acetate in ionic liquid precursor  

Microsoft Academic Search

At low temperature, Mn-doped ZnO mesocrystals have been prepared in a hydrated ionic liquid precursor tetrabutylammonium hydroxide (TBAH). A clear hysteresis with coercive field Hc=85 Oe and remanence Mr=0.0213emug?1 was observed in Zn0.95Mn0.05O mesocrystals, but only paramagnetism was observed in Zn0.95Mn0.05O nanorods. The morphologies, structures, chemical state, optical properties and room temperature ferromagnetic properties of the synthesized Zn0.95Mn0.05O samples could

Wenjun Xiao; Qin Chen; Ying Wu; Tinghua Wu; Lizong Dai



Ionic liquids as porogens for molecularly imprinted polymers: propranolol, a model study.  


The selectivity and rebinding capacity of molecularly imprinted polymers selective for propranolol (1) using the room temperature ionic liquids [BMIM][BF4], [BMIM][PF6], [HMIM][PF6] and [OMIM][PF6] and CHCl3 were examined. The observed IF (imprinting factor) values for MIPBF4, MIPPF6 and MIPCHCl3 were 1.0, 1.98 and 4.64, respectively. The longer chain HMIM and OMIM systems returned lower IF values of 1.1 and 2.3, respectively. MIPPF6 also showed a 25% binding capacity reduction vs. MIPCHCl3 (5 ?mol g(?1)vs. 7 ?mol g(?1) respectively). MIPCHCl3 and MIPPF6 differed in terms of BET surface area (306 m(2) g(?1)vs. 185 m(2) g(?1)), pore size (1.10 and 2.19 nm vs. 0.97 and 7.06 nm), the relative number of pores (Type A: 10.4 vs. 7.5%; Type B: 8.5 vs. 3.0%), and surface zeta potential (?37.9 mV vs. ?20.3 mV). The MIP specificity for 1 was examined by selective rebinding studies with caffeine (2) and ephedrine (3). MIPPF6 rebound higher quantities of 2 than MIPCHCl3, but this was largely due to non-specific binding. Both MIPCHCl3 and MIPPF6 showed a higher affinity for 3 than for 2. Reduction in the Room Temperature Ionic Liquid (RTIL) porogen volume had little impact on the polymer morphology, but did result in a modest decrease in IF from 2.6 to 2.3 and in the binding capacity (30% to 19%). MIPCHCl3 retained the highest template specificity on rebinding from CHCl3 (IF = 4.6) dropping to IF = 0.6 in MeOH/[BMIM][PF6]. The MIPCHCl3 binding capacity remained constant using CHCl3, CH2Cl2 and MeOH (46–52%), dropped to 6% on addition of [BMIM][PF6] and increased to 83% in H2O (but at the expense of specificity with IFH2O = 1.4). MIPPF6 rebinding from MeOH saw an increase in specific rebinding to IF = 4.9 and also an increase in binding capacity to 48% when rebinding 1 from MeOH and to 42% and 45% with H2O and CH2Cl2, respectively, although in the latter case the increased capacity was at the cost of specificity with IFCH2Cl2 = 1.2. Overall the MIPPF6 capacity and specificity were enhanced on addition of MeOH. PMID:24971654

Booker, Katherine; Holdsworth, Clovia I; Doherty, Cara M; Hill, Anita J; Bowyer, Michael C; McCluskey, Adam



Ionic liquids: the link to high-temperature molten salts?  


Due to their wide thermal windows, ionic liquids can be regarded as the missing link between aqueous/organic solutions and high-temperature molten salts. They can be employed efficiently for the coating of other metals with thin layers of tantalum, aluminum, and presumably many others at reasonable temperatures by electrochemical means. The development of ionic liquids, especially air and water stable ones, has opened the door for the electrodeposition of reactive elements such as, for example, Al, Ta, and Si, which in the past were only accessible using high-temperature molten salts or, in part, organic solvents. PMID:17521159

El Abedin, Sherif Zein; Endres, Frank



Alkyltributylphosphonium chloride ionic liquids: synthesis, physicochemical properties and crystal structure.  


A series of alkyltributylphosphonium chloride ionic liquids, prepared from tributylphosphine and the respective 1-chloroalkane, C(n)H(2n+1)Cl (where n = 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 12 or 14), is reported. This work is a continuation of an extended series of tetraalkylphosphonium ionic liquids, where the focus is on the variability of n and its impact on the physical properties, such as melting points/glass transitions, thermal stability, density and viscosity. Experimental density and viscosity data were interpreted using QPSR and group contribution methods and the crystal structure of propyl(tributyl)phosphonium chloride is detailed. PMID:22679620

Adamová, Gabriela; Gardas, Ramesh L; Nieuwenhuyzen, Mark; Puga, Alberto V; Rebelo, Luís Paulo N; Robertson, Allan J; Seddon, Kenneth R



Hydrolysis and Partial Recycling of a Chloroaluminate Ionic Liquid  

PubMed Central

Hydrolysis of the ionic liquid Et3NHCl-2AlCl3 and a process for recycling the triethylamine were studied. When the hydrolysis was carried out at a relatively high temperature, the released HCl could be absorbed more easily. With addition of sodium hydroxide to the aqueous hydrolysis solution, a feasible process for recycling triethylamine was developed, involving first distillation of triethylamine, followed by filtration of the aluminium hydroxide. The yield of recovered triethylamine was about 95%. The triethylhydrogenammonium chloride prepared from the recycled triethylamine was of good purity and could be reused to synthesize new chloroaluminate ionic liquids.

Fang, Ming-Hong; Wang, Li-Sheng



Direct observation of spiropyran phosphorescence in imidazolium ionic liquids  

NASA Astrophysics Data System (ADS)

Emission spectroscopy is used to investigate the photochromism of a spiropyran ester in imidazolium ionic liquids. While the spiropyran exhibits positive photochromism, the ring-opening reaction is slowed such that both fluorescence from the merocyanine form and phosphorescence from the spiro form are observed. These results illustrate the first example of spiropyran phosphorescence in ionic liquids and suggest that this system could be used to design a robust two-color emitting molecular device that depends on the state of the photochrome, where the state can be modulated by internal (the medium) and external (irradiation wavelength) factors.

Naughton, Sean P.; Gaudet, Robyn M.; Leslie, Anne A.; Keirstead, Amy E.



Development of ionic liquid-based lithium battery prototypes  

Microsoft Academic Search

The lab-scale manufacturing of Li\\/LiFePO4 and Li4Ti5O12\\/LiFePO4 stacked battery prototypes and their performance characterization are described here. The prototypes were realized in the frame of an European Project devoted to the development of greener and safer lithium batteries, based on ionic liquid electrolytes, for integration with photovoltaic panels. N-Butyl-N-methylpyrrolidinium bis(trifluoromethanesulfonyl)imide (PYR14TFSI) and N-butyl-N-methylpyrrolidinium bis(fluoro-methanesulfonyl)imide (PYR14FSI), selected as the ionic liquids

G.-T. Kim; S. S. Jeong; M.-Z. Xue; A. Balducci; M. Winter; S. Passerini; F. Alessandrini; G. B. Appetecchi


Pyrrolidinium-based ionic liquids doped with lithium salts: how does li(+) coordination affect its diffusivity?  


We present the characterization of LiX-doped room-temperature ionic liquids (ILs) based on the N-butyl-N-methyl pyrrolidinium (PYR14) cation with two fluorinated anions: (trifluoromethanesulfonyl)-(nonafluorobutanesulfonyl)imide (X?IM14) and bis(pentafluoroethanesulfonyl)imide (X?BETI). The new data are also compared with previous results on PYR14TFSI (bis(trifluoromethanesulfonyl)imide). Their local organization has been investigated via NMR nuclear Overhauser effect (NOE) experiments for {(1)H-(19)F} and {(1)H-(7)Li} that give us details on PYR14(+)/X(-) and PYR14(+)/Li(+) contacts. We confirm the presence of [Li(X)2](-) coordinated species in all systems. The long-range, intermolecular NOEs have been detected and provide information on the ions' organization beyond the first solvation sphere. The ionic conductivity, viscosity and self-diffusion coefficients of the ionic mixtures have also been measured. The activation energies for the diffusion of the individual ions and for the fluidity are compared with those for the pure ILs. Finally, density functional calculations on [Li(BETI)2](-), [Li(IM14)2](-), and [Li(TFSI)2](-) complexes demonstrate that the minimum energy structures for all systems correspond to a tetrahedral coordination of the Li-ion by four oxygen atoms of the anions. Assuming very simple key steps for the Li(+) diffusion process (i.e., the concerted breaking and formation of Li-O bonds or the rearrangement around a tetrahedrally coordinated Li(+)), we calculate activation barriers that agree well with the experimental results (approximately 46 kJ/mol, in all systems). PMID:25368963

Castiglione, Franca; Famulari, Antonino; Raos, Guido; Meille, Stefano V; Mele, Andrea; Appetecchi, Giovanni Battista; Passerini, Stefano



Highly selective ionic liquid-based microextraction method for sensitive trace cobalt determination in environmental and biological samples.  


A simple and rapid dispersive liquid-liquid microextraction procedure based on an ionic liquid (IL-DLLME) was developed for selective determination of cobalt (Co) with electrothermal atomic absorption spectrometry (ETAAS) detection. Cobalt was initially complexed with 1-nitroso-2-naphtol (1N2N) reagent at pH 4.0. The IL-DLLME procedure was then performed by using a few microliters of the room temperature ionic liquid (RTIL) 1-hexyl-3-methylimidazolium hexafluorophosphate [C(6)mim][PF(6)] as extractant while methanol was the dispersant solvent. After microextraction procedure, the Co-enriched RTIL phase was solubilized in methanol and directly injected into the graphite furnace. The effect of several variables on Co-1N2N complex formation, extraction with the dispersed RTIL phase, and analyte detection with ETAAS, was carefully studied in this work. An enrichment factor of 120 was obtained with only 6 mL of sample solution and under optimal experimental conditions. The resultant limit of detection (LOD) was 3.8 ng L(-1), while the relative standard deviation (RSD) was 3.4% (at 1 microg L(-1) Co level and n=10), calculated from the peak height of absorbance signals. The accuracy of the proposed methodology was tested by analysis of a certified reference material. The method was successfully applied for the determination of Co in environmental and biological samples. PMID:20171314

Berton, Paula; Wuilloud, Rodolfo G



Charge Transport and Glassy Dynamics in Ionic Liquids  

SciTech Connect

Ionic liquids (ILs) exhibit unique features such as low melting points, low vapor pressures, wide liquidus temperature ranges, high thermal stability, high ionic conductivity, and wide electrochemical windows. As a result, they show promise for use in variety of applications: as reaction media, in batteries and supercapacitors, in solar and fuel cells, for electrochemical deposition of metals and semiconductors, for protein extraction and crystallization, and many others. Because of the ease with which they can be supercooled, ionic liquids offer new opportunities to investigate long-standing questions regarding the nature of the dynamic glass transition and its possible link to charge transport. Despite the significant steps achieved from experimental and theoretical studies, no generally accepted quantitative theory of dynamic glass transition to date has been capable of reproducing all the experimentally observed features. In this Account, we discuss recent studies of the interplay between charge transport and glassy dynamics in ionic liquids as investigated by a combination of several experimental techniques including broadband dielectric spectroscopy, pulsed field gradient nuclear magnetic resonance, dynamic mechanical spectroscopy, and differential scanning calorimetry. Based on EinsteinSmoluchowski relations, we use dielectric spectra of ionic liquids to determine diffusion coefficients in quantitative agreement with independent pulsed field gradient nuclear magnetic resonance measurements, but spanning a broader range of more than 10 orders of magnitude. This approach provides a novel opportunity to determine the electrical mobility and effective number density of charge carriers as well as their types of thermal activation from the measured dc conductivity separately. We also unravel the origin of the remarkable universality of charge transport in different classes of glass-forming ionic liquids.

Sangoro, Joshua R [ORNL; Kremer, Friedrich [University of Leipzig



Charge transport and glassy dynamics in ionic liquids.  


Ionic liquids (ILs) exhibit unique features such as low melting points, low vapor pressures, wide liquidus temperature ranges, high thermal stability, high ionic conductivity, and wide electrochemical windows. As a result, they show promise for use in variety of applications: as reaction media, in batteries and supercapacitors, in solar and fuel cells, for electrochemical deposition of metals and semiconductors, for protein extraction and crystallization, and many others. Because of the ease with which they can be supercooled, ionic liquids offer new opportunities to investigate long-standing questions regarding the nature of the dynamic glass transition and its possible link to charge transport. Despite the significant steps achieved from experimental and theoretical studies, no generally accepted quantitative theory of dynamic glass transition to date has been capable of reproducing all the experimentally observed features. In this Account, we discuss recent studies of the interplay between charge transport and glassy dynamics in ionic liquids as investigated by a combination of several experimental techniques including broadband dielectric spectroscopy, pulsed field gradient nuclear magnetic resonance, dynamic mechanical spectroscopy, and differential scanning calorimetry. Based on Einstein-Smoluchowski relations, we use dielectric spectra of ionic liquids to determine diffusion coefficients in quantitative agreement with independent pulsed field gradient nuclear magnetic resonance measurements, but spanning a broader range of more than 10 orders of magnitude. This approach provides a novel opportunity to determine the electrical mobility and effective number density of charge carriers as well as their types of thermal activation from the measured dc conductivity separately. We also unravel the origin of the remarkable universality of charge transport in different classes of glass-forming ionic liquids. PMID:22082024

Sangoro, Joshua R; Kremer, Friedrich



Applications and Properties of Ionic Liquid- Based Gels and Soft Solid Composites  

NASA Astrophysics Data System (ADS)

Solid-liquid composites (gels) have a combination of properties that afford new material applications in which high solute diffusion is desirable. These composites have a soft-solid mechanical integrity and will not flow under gravity, but entrain a liquid matrix (i.e. 60-98 mass %) which allows for high diffusion and high reactivity. Room temperature ionic liquid (RTILs) are molten organic salts with a melting point below room temperature and negligible vapor pressure. If the RTILs are used as the liquid component of a gel, then the gel matrix will not evaporate (unlike other organic solvents) and may be used for long term applications. This thesis research applies RTIL gels for two new applications; carbon dioxide/nitrogen separation and chemical warfare agent (CWA) barrier and decontamination. Separating CO2 from the flue gas of coal and gas fired power-plants is an increasingly economically and environmentally important gas separation. In this first study, RTIL gels are cast in a supported membrane and gas permeability and ideal selectivity are measured. The RTIL matrix has an inherent affinity for CO2 and provides a high diffusion, hence high permeability (i.e. 500-700 barrer). The solidifying component is a low molecular-weight organic gelator (LMOG) which through physical bonding interactions (i.e. hydrogen bonding, pi-pi stacking and van der Walls forces) forms an entangled network which provides mechanical stability (i.e. increase trans-membrane pressure required to expel selective material from the support). In these studies two LMOGs and five RTILs are used to make supported gel membranes and determine gas permeability and temperature dependent trends. The second application for RTIL gels is a decontaminating barrier for CWAs and toxic industrial compounds (TICs). In these studies a layer of RTIL gel is applied on top of a substrate contaminated with a CWA simulant (i.e. chloroethylethylsulfide, CEES). The gel performs well as a barrier, preventing CEES vapor from penetrating the gel. Simultaneously, the RTIL gel actively decontaminated the substrate by reacting CEES with a sacrificial amine. The RTIL gel barrier was able to decontaminate up to 98% of the CEES applied to a painted steel substrate. Two gel barriers are tested: (1) RTIL gel with a LMOG solidifying agent, and (2) RTIL gel with a polymeric cross-linked network solidifying agent. The polymer gel provided a more mechanically robust barrier, however, the LMOG gel decontaminated at a faster rate. These new applications are but two of many possible applications for RTIL gels. Their negligible vapor pressure affords long term application in ambient conditions and their unique chemistry allows them to be tailored for specific applications.

Voss, Bret Alan McGinness


Surface interactions, corrosion processes and lubricating performance of protic and aprotic ionic liquids with OFHC copper  

NASA Astrophysics Data System (ADS)

In order to select possible candidates for use as lubricants or as precursors of surface coatings, the corrosion and surface interactions of oxygen-free high conductivity (OFHC) copper with two new protic (PIL) and four aprotic (APIL) room-temperature ionic liquids have been studied. The PILs, with no heteroatoms in their composition, are the triprotic di[(2-hydroxyethyl)ammonium] succinate (MSu) and the diprotic di[bis-(2-hydroxyethyl)ammonium] adipate (DAd). The four APILs contain imidazolium cations with short or long alkyl chain substituents and reactive anions: 1-ethyl-3-methylimidazolium phosphonate ([EMIM]EtPO3H); 1-ethyl-3-methylimidazolium octylsulfate ([EMIM]C8H17SO4); 1-hexyl-3-methylimidazolium tetrafluoroborate ([HMIM]BF4) and 1-hexyl-3-methylimidazolium hexafluorophosphate ([HMIM]PF6). Contact angles between the ionic liquids and OFHC copper surface were measured. Mass and roughness changes of OFHC copper after 168 h in contact with the ionic liquids have been determined. Copper surfaces were studied by XRD, SEM-EDX and XPS surface analysis. FTIR spectra of the liquid phases recovered after being in contact with the copper surface were compared with that of the neat ionic liquids. The lowest corrosion rate is observed for the diprotic ammonium adipate PIL (DAd), which gives low mass and surface roughness changes and forms adsorbed layers on copper, while the triprotic ammonium succinate salt (MSu) produces a severe corrosive attack by reaction with copper to form a blue crystalline solid, which has been characterized by FTIR and thermal analysis (TGA). All imidazolium APILs react with copper, with different results as a function of the anion. As expected, [EMIM]C8H17SO4 reacts with copper to form the corresponding copper sulphate salt. [EMIM]EtPO3H produces severe corrosion to form a phosphonate-copper soluble phase. [HMIM]BF4 gives rise to the highest roughness increase of the copper surface. [HMIM]PF6 shows the lowest mass and roughness changes of the four imidazolium ionic liquids due to the formation of a solid layer containing phosphorus and fluorine. The results described in the present study are in agreement with the outstanding good tribological performance of the diprotic ammonium adipate (DAd) ionic liquid for the copper-copper contact, in pin-on-disc tests, preventing wear and giving a very low friction coefficient of 0.01. Under the same conditions, [HMIM]PF6 gives a friction value of 0.03, while the reactivity of MSu towards copper produces maximum friction peaks of 0.05. In contrast with the absence of surface damage on copper, an abrasive wear mechanism is observed for MSu and [HMIM]PF6. The results confirm a better lubricating performance for a lower corrosion rate.

Espinosa, Tulia; Sanes, José; Jiménez, Ana-Eva; Bermúdez, María-Dolores



Modified thermodynamics in ionic liquids for controlled electrocrystallization of nanocubes, nanowires, and crystalline thin films of silver-tetracyanoquinodimethane.  


Electrocrystallization of nanocubes, nanorods, nanowires, and crystalline thin films of silver-tetracyanoquinodimethane (AgTCNQ) onto glassy carbon, indium tin oxide, and platinum electrodes can be achieved from ionic liquids containing dissolved TCNQ and Ag(I) salts. In conventional molecular organic solvents, such as acetonitrile, the reduction of TCNQ and Ag(+) occurs at almost the same potential. In contrast, the different thermodynamics that apply to the room temperature ionic liquid, 1-n-butyl-3-methylimidazolium tetrafluoroborate (BMIMBF(4)), give rise to a large potential separation in the two processes, which enables electrocrystallization of AgTCNQ to be undertaken via two distinctly different, potential-dependent mechanisms. Cyclic and microelectrode voltammetric, chronoamperometric, together with microscopic and spectroscopic techniques reveal that AgTCNQ nanostuctures of controlled morphology, size, density, and uniformity can be achieved by tuning the electrocrystallization parameters such as potential, stoichiometric ratio of Ag(+) and TCNQ, and their concentrations, time, and ionic liquid viscosity by altering the water content. In the potential range of -0.1 to 0.3 V vs Fc(0/+) (Fc = ferrocene), electrocrystallization occurs when Ag is deposited at electrode defect sites via a progressive nucleation and 3-D growth mechanism followed by reaction with TCNQ to produce structures ranging from nanocubes to nanowires. At higher stoichiometric concentrations of Ag(+) and more negative potentials (<-0.1 V vs Fc(0/+)), extremely thin crystalline films could be obtained via overpotential deposition. Infrared and Raman spectroscopy, elemental analysis, together with X-ray diffraction and scanning electron microscopy all confirm the formation of highly pure AgTCNQ nanomaterials, which exhibit differences in morphology but not phase. The study highlights the capability of the electrocrystallization method to precisely control the morphology of nanomaterials, and also the unprecedented opportunities provided by using ionic liquids as the medium for preparation of technologically important metal-TCNQ charge transfer complexes. PMID:19831410

Zhao, Chuan; MacFarlane, Douglas R; Bond, Alan M



Growth of Gold Nanosheets and Nanopolyhedra in Pyrrolidinium-Based Ionic Liquids: Investigation of the Cation Effect on the Resulting Morphologies  

SciTech Connect

Large gold nanosheets and small gold polyhedra have been successfully synthesized in room-temperature ionic liquids (ILs) by an ionothermal reduction of HAuCl{sub 4} under N{sub 2} atmosphere, without using any additives. The effect of the organic cation on the final morphologies of the gold particles has been studied, and a series of pyrrolidinium-, imidazolium-, and quaternary amine-based ionic liquids have been investigated by scanning electron microscopy (SEM) and X-ray diffraction (XRD) measurements. Our results show that these ILs favor the anisotropic growth of gold by acting as template agents and that only gold microspheres can be obtained with the IL containing a reductive functionality.

Bouvy, Claire [ORNL; Baker, Gary A [ORNL; Yin, Hongfeng [ORNL; Dai, Sheng [ORNL



Simultaneous determination of dopamine, ascorbic acid, and uric acid using carbon ionic liquid electrode.  


A recently constructed carbon composite electrode using room temperature ionic liquid as pasting binder was employed as a novel electrode for sensitive, simultaneous determination of dopamine (DA), ascorbic acid (AA), and uric acid (UA). The apparent reversibility and kinetics of the electrochemical reaction for DA, AA, and UA found were improved significantly compared to those obtained using a conventional carbon paste electrode. The results show that carbon ionic liquid electrode (CILE) reduces the overpotential of DA, AA, and UA oxidation, without showing any fouling effect due to the deposition of their oxidized products. In the case of DA, the oxidation and reduction peak potentials appear at 210 and 135mV (vs Ag/AgCl, KCl, 3.0M), respectively, and the CILE shows a significantly better reversibility for dopamine. The oxidation peak due to the oxidation of AA occurs at about 60mV. For UA, a sharp oxidation peak at 340mV and a small reduction peak at 250mV are obtained at CILE. Differential pulse voltammetry was used for the simultaneous determination of ternary mixtures of DA, AA, and UA. Relative standard deviation for DA, AA, and UA determinations were less than 3.0% and DA, AA, and UA can be determined in the ranges of 2.0x10(-6)-1.5x10(-3), 5.0x10(-5)-7.4x10(-3), and 2.0x10(-6)-2.2x10(-4)M, respectively. The method was applied to the determination of DA, AA, and UA in human blood serum and urine samples. PMID:17069745

Safavi, Afsaneh; Maleki, Norouz; Moradlou, Omran; Tajabadi, Fariba



Conductivity, spectroscopic, and computational investigation of H3O+ solvation in ionic liquid BMIBF4.  


The hydrogen ion is one of the most important species in aqueous solutions, as well as in protic ionic liquids (PILs). PILs are important potential alternatives to H2O for swelling the proton exchange membranes (PEMs) and improving the high-temperature performance of fuel cells. The hydrogen ion (H(+)) or hydronium (H3O(+)) solvation mechanism is not only a fundamental principle of acid/base chemistry in ionic liquids but also key to understanding the charge- and proton-transport properties of the PIL solutions. In this paper, a PIL system was prepared by mixing 1-butyl-3-methyl-imidazolium tetrafluoroborate (BMIBF4) IL with an aqueous solution of a strong acid, HBF4. Water can be partially evaporated from the solution under a vacuum at room temperature. Conductivity and vibrational spectroscopy (IR and Raman) measurements were used in combination with density functional theory (DFT) calculations to characterize the molecular-level solvation of H(+) and H2O in the IL solution. When water is present at high molar fraction, the cations (BMI(+) and H(+)) and anions (BF4(-)) are both solvated by water and the solutions have high conductivity. After water evaporation, the PIL solution has excess H(+) and reduced conductivity, which is still significantly higher than that of pure BMIBF4. Vibrational spectroscopy suggests that the BMI(+) and BF4(-) ions are desolvated from water during the water evaporation. DFT calculations assist the interpretation of the vibrational spectroscopy and show that the remaining water is in the form of H3O(+) solvated by the IL molecular ions. Hence, the species remaining after evaporation is a ternary PIL consisting of BMI(+) cation, BF4(-) anion, and H3O(+) cation. The H3O(+) may be the principle charge carrier in the PIL solution and responsible for the high solution conductivity. PMID:23688053

Yu, Lei; Clifford, Jeremy; Pham, Toan T; Almaraz, Eduardo; Perry, Fredrick; Caputo, Gregory A; Vaden, Timothy D



Electric control of magnetism at room temperature  

PubMed Central

In the single-phase multiferroics, the coupling between electric polarization (P) and magnetization (M) would enable the magnetoelectric (ME) effect, namely M induced and modulated by E, and conversely P by H. Especially, the manipulation of magnetization by an electric field at room-temperature is of great importance in technological applications, such as new information storage technology, four-state logic device, magnetoelectric sensors, low-power magnetoelectric device and so on. Furthermore, it can reduce power consumption and realize device miniaturization, which is very useful for the practical applications. In an M-type hexaferrite SrCo2Ti2Fe8O19, large magnetization and electric polarization were observed simultaneously at room-temperature. Moreover, large effect of electric field-controlled magnetization was observed even without magnetic bias field. These results illuminate a promising potential to apply in magnetoelectric devices at room temperature and imply plentiful physics behind them. PMID:22355737

Wang, Liaoyu; Wang, Dunhui; Cao, Qingqi; Zheng, Yuanxia; Xuan, Haicheng; Gao, Jinlong; Du, Youwei



Electric control of magnetism at room temperature.  


In the single-phase multiferroics, the coupling between electric polarization (P) and magnetization (M) would enable the magnetoelectric (ME) effect, namely M induced and modulated by E, and conversely P by H. Especially, the manipulation of magnetization by an electric field at room-temperature is of great importance in technological applications, such as new information storage technology, four-state logic device, magnetoelectric sensors, low-power magnetoelectric device and so on. Furthermore, it can reduce power consumption and realize device miniaturization, which is very useful for the practical applications. In an M-type hexaferrite SrCo(2)Ti(2)Fe(8)O(19), large magnetization and electric polarization were observed simultaneously at room-temperature. Moreover, large effect of electric field-controlled magnetization was observed even without magnetic bias field. These results illuminate a promising potential to apply in magnetoelectric devices at room temperature and imply plentiful physics behind them. PMID:22355737

Wang, Liaoyu; Wang, Dunhui; Cao, Qingqi; Zheng, Yuanxia; Xuan, Haicheng; Gao, Jinlong; Du, Youwei



Ionic liquid-based single drop microextraction of ultra-trace copper in food and water samples before spectrophotometric determination  

NASA Astrophysics Data System (ADS)

In this work, room temperature ionic liquid (RTIL) 1-butyl-3-methylimidazolium hexafluorophosphate ([C 4mim]PF 6) was used as extractant in single drop microextraction (SDME). The traditionally volatile organic extractants were substituted by this green reagent, which changed SDME preconcentration into environmentally friendly method, relatively. After this pretreatment, ultra-trace copper in water and food samples could be accurately detected by spectrophotometer. This study was focused on the improvement of the analytical performance of spectrophotometric determination, expanding its applications. The influence factors relevant to IL-SDME, such as absorption spectra of complex, drop volume of RTIL, stirring rate and time, concentration of chelating agent, pH, and salt effect were studied systematically. Under the optimal conditions, the limit of detection (LOD) was 0.15 ?g L -1 with an enhancement factor (EF) of 33. The proposed method was green, simple, rapid, sensitive, and cost-efficient.

Wen, Xiaodong; Deng, Qingwen; Guo, Jie



60Co ?-irradiation initiated polymerization in ionic liquids - The effect of carbon-chain length of monomer  

NASA Astrophysics Data System (ADS)

Gamma-radiation initiated polymerization of Methyl methacrylate (MMA) and Butyl methacrylate (BMA) was carried out in room temperature ionic liquid (RTIL) [Me3NC2H4OH]+ [ZnCl3]- and RTIL/organic solutions. MMA and BMA were selected as the represents of vinyl monomers in order to understand the effect of side-chain carbon length on properties of the resulting polymer. Although both PMMA and PBMA from RTIL/organic solution at high RTIL content have significantly higher molecular weight than those at RTIL 20 vol.%, their molecular weight distributions (MWDs) are clearly different. For polymerization in RTIL/THF and RTIL/MeOH solutions, PMMA has a single-modal MWD while PBMA has a multi-modal MWD. This difference is probably due to the better compatibility of PMMA with RTIL/THF and RTIL/MeOH solutions, though PMMA is insoluble in pure methanol.

Yaodong, Liu; Guozhong, Wu; Dewu, Long; Mingying, Qi; Zhiyong, Zhu



Identification of Helicity-Dependent Photocurrents from Topological Surface States in Bi2Se3 Gated by Ionic Liquid  

PubMed Central

Dirac-like surface states on surfaces of topological insulators have a chiral spin structure with spin locked to momentum, which is interesting in physics and may also have important applications in spintronics. In this work, by measuring the tunable helicity-dependent photocurrent (HDP), we present an identification of the HDP from the Dirac-like surface states at room temperature. It turns out that the total HDP has two components, one from the Dirac-like surface states, and the other from the surface accumulation layer. These two components have opposite directions. The clear gate tuning of the electron density as well as the HDP signal indicates that the surface band bending and resulted surface accumulation are successfully modulated by the applied ionic liquid gate, which provides a promising way to the study of the Dirac-like surface states and also potential applications in spintronic devices. PMID:24809330

Duan, Junxi; Tang, Ning; He, Xin; Yan, Yuan; Zhang, Shan; Qin, Xudong; Wang, Xinqiang; Yang, Xuelin; Xu, Fujun; Chen, Yonghai; Ge, Weikun; Shen, Bo



Fabrication of fiber supported ionic liquids and methods of use  


One or more embodiments relates to the production of a fabricated fiber having an asymmetric polymer network and having an immobilized liquid such as an ionic liquid within the pores of the polymer network. The process produces the fabricated fiber in a dry-wet spinning process using a homogenous dope solution, providing significant advantage over current fabrication methods for liquid-supporting polymers. The fabricated fibers may be effectively utilized for the separation of a chemical species from a mixture based on the selection of the polymer, the liquid, and the solvent utilized in the dope.

Luebke, David R; Wickramanayake, Shan



Investigation of the room temperature annealing peak in ionomers  

SciTech Connect

A number of studies appearing in the literature have documented an endothermic peak in differential scanning calorimetry (DSC) scans for ethylene-methacrylic acid copolymer ionomers which appears only upon annealing at room temperature. This peak has been attributed to either polyethylene crystallites, ionic crystallite, or water absorption. In a novel polyurethane cationomer with a quarternized amine contained in hard segment, the same phenomena has been found in DSC scans when the neutralizing anion is bromine or iodine. Since this material does not crystallize, the authors were able to conclusively eliminate crystallization as the cause of the endotherm. The extended x-ray absorption fine structure (EXAFS) of bromine has been measured to differentiate between water absorption and ionic crystallites. Spectra were collected above and below the temperature corresponding to the endothermic peak. The results of the EXAFS analysis will be presented.

Goddard, R.J.; Grady, B.P.; Cooper, S.L. [Univ. of Wisconsin-Madison, WI (United States)



Characterization of an iodine-based ionic liquid ion source and studies on ion fragmentation  

E-print Network

Electrosprays are a well studied source of charged droplets and ions. A specific subclass is the ionic liquid ion source (ILIS), which produce ion beams from the electrostatically stressed meniscus of ionic liquids. ILIS ...

Fedkiw, Timothy Peter



Synthesis of fluoromethylated materials derived from 2-trifluoromethyl acrylic acid phenethyl ester in an ionic liquid  

Microsoft Academic Search

Synthesis of fluoromethylated materials via Michael addition reaction catalyzed by l-proline in an ionic liquid, is described. Further, the synthesis and synthetic application of zinc reagents generated in an ionic liquid, giving trifluoromethylated materials, are described.

Abdellatif M Salaheldin; Zhao Yi; Tomoya Kitazume



Dynamics of Glass Relaxation at Room Temperature  

NASA Astrophysics Data System (ADS)

The problem of glass relaxation under ambient conditions has intrigued scientists and the general public for centuries, most notably in the legend of flowing cathedral glass windows. Here we report quantitative measurement of glass relaxation at room temperature. We find that Corning® Gorilla® Glass shows measurable and reproducible relaxation at room temperature. Remarkably, this relaxation follows a stretched exponential decay rather than simple exponential relaxation, and the value of the stretching exponent (?=3/7) follows a theoretical prediction made by Phillips for homogeneous glasses.

Welch, Roger C.; Smith, John R.; Potuzak, Marcel; Guo, Xiaoju; Bowden, Bradley F.; Kiczenski, T. J.; Allan, Douglas C.; King, Ellyn A.; Ellison, Adam J.; Mauro, John C.



Dynamics of glass relaxation at room temperature.  


The problem of glass relaxation under ambient conditions has intrigued scientists and the general public for centuries, most notably in the legend of flowing cathedral glass windows. Here we report quantitative measurement of glass relaxation at room temperature. We find that Corning® Gorilla® Glass shows measurable and reproducible relaxation at room temperature. Remarkably, this relaxation follows a stretched exponential decay rather than simple exponential relaxation, and the value of the stretching exponent (?=3/7) follows a theoretical prediction made by Phillips for homogeneous glasses. PMID:23848901

Welch, Roger C; Smith, John R; Potuzak, Marcel; Guo, Xiaoju; Bowden, Bradley F; Kiczenski, T J; Allan, Douglas C; King, Ellyn A; Ellison, Adam J; Mauro, John C



High performance ultracapacitors with carbon nanomaterials and ionic liquids  


The present invention is directed to the use of carbon nanotubes and/or electrolyte structures in various electrochemical devices, such as ultracapacitors having an ionic liquid electrolyte. The carbon nanotubes are preferably aligned carbon nanotubes. Compared to randomly entangled carbon nanotubes, aligned carbon nanotubes can have better defined pore structures and higher specific surface areas.

Lu, Wen; Henry, Kent Douglas




EPA Science Inventory

Ambient temperature ionic liquids comprising 1,3-dialkylimidazolium cations have shown great promise as alternative solvents in view of their negligible vapor pressure, ease of handling and potential for recycling. An efficient solventless protocol for the preparation of a wide v...


Friedel-Crafts acylation reactions in pyridinium based ionic liquids  

Microsoft Academic Search

The Friedel-Crafts acylations of representative aromatic compounds with acetic anhydride in pyridinium based ionic liquids (ILs) were investigated. The effect of factors such as reactant composition, catalyst-IL composition, catalyst dosage and reaction temperature were studied. The reactions were found to proceed under relatively mild conditions with excellent conversions; and a simple product isolation procedure was achieved. ILs could also be

Ying Xiao; Sanjay V. Malhotra



Zn, Ti and Si nanowires by electrodeposition in ionic liquid  

Microsoft Academic Search

An electrochemical route for the fabrication of zinc, titanium and silicon nanowires from ionic liquid (IL) based plating solutions is presented. Thanks to the large potential window of IL and good solubility of the corresponding anhydrous chloride salts, the presented method proceeds by a kinetically controlled electrochemical decoration of step-edges at highly oriented pyrolytic graphite surface. Resulting rather crystalline nanowires

Claire Fournier; Frédéric Favier



Studies of inherently conducting polymers in ionic liquids  

Microsoft Academic Search

In this dissertation, the effect of ionic liquid (IL) or classical electrolyte (CE) employed on the redox behaviour of many inherently conducting polymers (ICPs) was investigated with the ultimate goal of producing flexible batteries. ICPs can be used in a range of unique applications, and also to replace many metal conductors or inorganic semiconductors. Commercialisation of ICPs has, however, been

Jakub Mazurkiewicz




EPA Science Inventory

Ionic Liquids have been suggested as "greener" replacements to traditional solvents. However, the environmental impacts of the life cycle phases have not been studied. Such a "cradle to gate" Life Cycle Assessment (LCA) for comparing the environmental impact of various solvents...


Benzene solubility in ionic liquids: working toward an understanding of liquid clathrate formation.  


The solubility of benzene in 15 imidazolium, pyrrolidinium, pyridinium, and piperidinium ionic liquids has been determined; the resulting, benzene-saturated ionic liquid solutions, also known as liquid clathrates, were examined with (1) H and (19) F nuclear magnetic resonance spectroscopy to try and understand the molecular interactions that control liquid clathrate formation. The results suggest that benzene interacts primarily with the cation of the ionic liquid, and that liquid clathrate formation (and benzene solubility) is controlled by the strength of the cation-anion interactions, that is, the stronger the cation-anion interaction, the lower the benzene solubility. Other factors that were determined to be important in the final amount of benzene in any given liquid clathrate phase included attractive interactions between the anion and benzene (when significant), and larger steric or free volume demands of the ions, both of which lead to greater benzene solubility. PMID:25297708

Pereira, Jorge F B; Flores, Luis A; Wang, Hui; Rogers, Robin D



Development of non-flammable lithium secondary battery with room-temperature ionic liquid electrolyte: Performance of electroplated Al film negative electrode  

Microsoft Academic Search

The negative electrode performance of the electroplated Al film electrode in the LiCl saturated AlCl3–1-ethyl-3-methylimizadolium chloride (EMIC)+SOCl2 melt as the electrolyte for use in non-flammable lithium secondary batteries was evaluated. In the cyclic voltammogram of the electroplated Al film electrode in the melt, the oxidation and reduction waves corresponding to the electrochemical insertion\\/extraction reactions of the Li+ ion were observed

Koichi Ui; Keigo Yamamoto; Kohei Ishikawa; Takuto Minami; Ken Takeuchi; Masayuki Itagaki; Kunihiro Watanabe; Nobuyuki Koura



Ionic liquid analogous formed from magnesium chloride hexahydrate and its physico-chemical properties  

Microsoft Academic Search

In this paper, a homogeneous, colorless ionic liquid analogous containing choline chloride and magnesium chloride hexahydrate is reported. The structure of the ionic liquid analogous is preliminarily investigated by Fourier transform infrared spectroscopy (FTIR). It is shown that the magnesium chloride hexahydrate bonds via hydrogen bonds with choline chloride. The physico-chemical properties of the ionic liquid analogous such as melting

Huaiyou Wang; Yan Jing; Xiaohuai Wang; Ying Yao; Yongzhong Jia



The use of ionic liquids based on choline chloride for metal deposition: A green alternative?  

Microsoft Academic Search

Ionic liquids are studied intensively for different applications. They tend to be denoted as “green solvents”, largely because of their low vapour pressure. In recent years toxicity and biotoxicity of ionic liquids have also been investigated, which proved that not all of these are “green”. In this paper the use of ionic liquids based on choline chloride and ethylene glycol

Kurt Haerens; Edward Matthijs; Andrzej Chmielarz; Bart Van der Bruggen



Solvent extraction of rare-earth ions based on functionalized ionic liquids  

SciTech Connect

We herein report the achievement of enhanced extractabilities and selectivities for separation of rare earth elements based on functionalized ionic liquids. This work highlights the potential of developing a comprehensive ionic liquid-based extraction strategy for rare earth elements using ionic liquids as both extractant and diluent.

Sun, Xiaoqi [ORNL; Dai, Sheng [ORNL; Luo, Huimin [ORNL



Ionic Liquid Ion Source Emitter Arrays Fabricated on Bulk Porous Substrates for Spacecraft Propulsion  

E-print Network

Propulsion Daniel George Courtney, Paulo Lozano June 2011 SSL # 9-11 #12;#12;Ionic Liquid Ion Source Emitter;Ionic Liquid Ion Source Emitter Arrays Fabricated on Bulk Porous Substrates for Spacecraft PropulsionIonic Liquid Ion Source Emitter Arrays Fabricated on Bulk Porous Substrates for Spacecraft


Electrolytic Conductivity of Four Imidazolium-Based Ionic Liquids  

NASA Astrophysics Data System (ADS)

In this article, electrolytic (ionic) conductivity measurements of four ionic liquids (ILs), namely, 1-ethyl-3-methylimidazolium bis[(trifluoromethyl)sulfonyl] imide ([Cmim][NTf]), 1-ethyl-3-methylimidazolium trifluoromethanesulfonate ([Cmim][OTf]), 1-hexyl-3-methylimidazolium bis[(trifluoromethyl)sulfonyl]imide ([Cmim][NTf]), and 1-ethyl-3-methylimidazolium ethyl sulfate ([Cmim][EtSO]) (ECOENG212), were performed in a temperature range of (288.15 to 333.15) K. [Cmim][NTf] was chosen to be a reference ionic liquid for several properties, including the electrolytic conductivity by the IUPAC Project 2002-005-1-100. For that reason, the measurements performed with that ionic liquid primarily serve the purpose to validate the instrumentation and the experimental procedure used in this work. The measurements were carried out using a complex impedance method, applying a novel electronic device designed and constructed for this purpose. The complete setup includes a Schott Instruments LF 913 T, used as a four-electrode conductivity cell, and a lock-in amplifier. The cell was calibrated using standard reference KCl aqueous solutions. The measurements of the impedance of the conductivity cell were carried out along a range of frequencies from (0.2 to 30) kHz, and the results were extrapolated to infinite frequency, in order to determine the electrolytic conductivity of the liquid samples. The results obtained for the ionic liquid [Cmim][NTf] were compared to reference data, and it was estimated that the overall uncertainty of the present results is better than 2 %. All the data obtained were compared with available literature data, and were analyzed and discussed in respect to the effect of temperature, cation alkyl chain length, and anion.

Calado, Marta S.; Diogo, João C. F.; Correia da Mata, José L.; Caetano, Fernando J. P.; Visak, Zoran P.; Fareleira, João M. N. A.



Template assisted electrodeposition of germanium and silicon nanowires in an ionic liquid.  


In this paper we report for the first time on the room temperature template synthesis of germanium and silicon nanowires by potentiostatic electrochemical deposition from the air- and water stable ionic liquid 1-butyl-1-methylpyrrolidinium bis(trifluoromethylsulfonyl)amide ([Py(1,4)]Tf(2)N) containing GeCl(4) and SiCl(4) as a Ge and Si source, respectively. Commercially-available track-etched polycarbonate membranes (PC) with an average nominal pore diameter of 90-400 nm were used as templates. Ge and Si nanowires with an average diameter corresponding to the nanopores' diameter and lengths of a few micrometres were reproducibly obtained. Structural characterization of the nanowires was performed by EDX, TEM, HR-SEM and Raman spectroscopy. Despite the rough surface of the nanowires, governed mostly by the original shape of the nanopore's wall of the commercially-available PC membrane, preliminary structural characterizations demonstrate the promising prospective of this innovative elaboration process compared to constraining high vacuum and high temperature methods. PMID:18936846

Al-Salman, R; Mallet, J; Molinari, M; Fricoteaux, P; Martineau, F; Troyon, M; Zein El Abedin, S; Endres, F



Nanoscale ionic graphene material with liquid-like behavior in the absence of solvent  

NASA Astrophysics Data System (ADS)

A nanoscale ionic graphene hybrid material with liquid-like behavior was obtained by using tertiary amine as corona and sulfonate anions as canopy. The microstructures and the rheological property of the solvent-free graphene nanofluid (G-PEGs) had been extensively characterized by various analytical techniques. The content of graphene was up to 12.05 wt%. The thickness of G-PEGs ranged from 2 nm to 5 nm. The conductivity of G-PEGs exhibited that the percolation threshold was about 0.99 vol%. In addition, the G-PEGs had relative low viscosity at room temperature (67.6 pa s at 20 °C). Most importantly, the G-PEGs showed excellent dispersion in solvents, such as water and ethanol. Those unique properties of G-PEGs may offer new scientific and technical opportunities for the applications of graphene. At the same time, the facile route to G-PEGs can be used in the fabrication of various GO or graphene based composite materials.

Li, Peipei; Zheng, Yaping; Wu, Yiwei; Qu, Ping; Yang, Ruilu; Zhang, Aibo



Green chemical functionalization of multiwalled carbon nanotubes with poly(?-caprolactone) in ionic liquids  

NASA Astrophysics Data System (ADS)

Multiwalled carbon nanotubes (MWNTs) have been successfully functionalized by free radical addition of 4,4'-azobis(4-cyanopentanol) in aqueous media to generate the terminal-hydroxyl-modified MWNTs (MWNT-OH), followed by surface-initiated in situ ring-opening polymerization of ?-caprolactone in 1-butyl-3-methylimidazolium tetrafluoroborate (BmimBF 4) to obtain poly(?-caprolactone)-grafted MWNTs (MWNT- g-PCL). Spectroscopic methods in conjunction with electron microscopy clearly revealed that hairy PCL chains were chemically attached to the surface of MWNTs to form core-shell nanostructures with the latter as core and the former as shell. With increasing polymerization time from 2 to 8 h, the amount of the grafted-PCL synthesized in BmimBF 4 varies from 30.6 to 62.7 wt%, which is clearly higher than that (41.5 wt%) obtained in 1,2-dichlorobenzene under comparable conditions (8 h). The proposed methodology here uses water and room temperature ionic liquids (RTILs) as the reaction media and promises a green chemical process for functionalizing nanotubes.

Yang, Yingkui; Qiu, Shengqiang; He, Chengen; He, Wenjie; Yu, Linjuan; Xie, Xiaolin



Extraction of arsenic in a soil of the blackfoot disease endemic area with ionic liquids  

NASA Astrophysics Data System (ADS)

Speciation of arsenic in the soil of the old blackfoot disease endemic area in the Southern Taiwan has been studied by X-ray absorption near edge structural (XANES) and extended X-ray absorption fine structural (EXAFS) spectroscopy. Experimentally, at the contact time of 30-180 min, 30-40% of As(III) and 40-60% of As(V) in the soil can be extracted with a room temperature ionic liquid (RTIL) [BMI][BF4] (1-butyl-3-methylimidazolium tetrafluoroborate). For the relatively hydrophobic RTIL [BMI][PF6] (1-butyl-3-methylimidazolium hexafluorophosphate), on the contrary, 10-15% of As(III) and 20-25% of As(V) can be extracted. By XANES, it is found that an enhanced oxidation of the extracted As(III) (As(III)?As(V)) in the RTIL may occur during the extraction processes. The refined EXAFS spectra also indicate that the bond distances of As(III)-N and As(V)-N in the arsenic-extracted RTILs are 1.76-1.78 and 1.68-1.70

Liao, C.-Y.; Wang, H. Paul; Peng, C.-Y.; Kang, H.-Y.; Wei, Y.-L.



Extraction of arsenic from a soil in the blackfoot disease endemic area with ionic liquids  

NASA Astrophysics Data System (ADS)

Speciation of arsenic extracted with room temperature ionic liquids (RTILs) ([bmim][BF 4] (1-butyl-3-methylimidazolium tetrafluoroborate) and [bmim][PF 6] (1-butyl-3-methylimidazolium hexafluorophosphate)) from an As-humic acid (As-HA) complex contaminated soil (As-HA/soil) in a blackfoot disease endemic area has been studied by X-ray absorption (near edge structure (XANES) and extended X-ray absorption fine structure (EXAFS)) spectroscopy. About 45% of arsenic in the As-HA/soil can be extracted with [bmim][BF 4] while the relatively less hydrophilic [bmim][PF 6] extracts 25% of arsenic. The extracted arsenic in the [bmim][BF 4] and [bmim][PF 6] from the As-HA/soil possesses mainly As(III) species, suggesting that at least two reaction paths may be involved in the extraction process: (1) splitting of As-HA and (2) reduction of As(V) to As(III). The refined EXAFS spectra also indicate that the As(III) extracted in the RTILs possesses the AsO 2- structure, which has the As-O bond distances of 1.77-1.79 Å and coordination numbers of 4.0-4.2.

Liao, Chang-Yu; Peng, Ching-Yu; Wang, Hong-Chung; Kang, Hsu-Ya; Paul Wang, H.



Concentration-dependent luminescence of ionic liquids containing trialkyl(pentafluorocyclotriphosphazenyl)ammonium moieties.  


Room-temperature ionic liquid compounds (CpzNR3(+)X(-)) consisting of trialkyl(pentafluorocyclotriphosphazenyl)ammonium (CpzNR3(+)) and anions (X(-)) such as chloride and bis(trifluoromethylsulfonyl)imide (TFSI(-)) emitted blue luminescence under an excitation of 360 nm. The luminescent quantum yields (?em) of CpzNR3(+)X(-) were determined to be 0.012-0.044 in methanol solution at 360 nm excitation. The excitation spectra and luminescent lifetime (?) measurements indicated the existence of two luminescent species. The appearance of luminescence from the pentafluorocyclotriphosphazenyl (Cpz) chromophore at longer wavelengths and the dependence of the luminescent intensity upon the concentration of CpzNR3(+)X(-) revealed that the observed luminescence was attributed to the J-aggregates of the Cpz chromophore. The formation of these aggregates was also evidenced by the concentration-dependent (1)H-NMR chemical shift. The J-aggregates involved both luminescent aggregates of smaller sizes with shorter ? (1.0 ns) and those of larger sizes with longer ? (5.0 ns). The ?em of the aggregates with larger sizes were enhanced with increasing CpzNR3(+)X(-) concentration. Thus, the luminescence stemming from the luminescent aggregates can be reasonably explained by the "aggregation-induced enhanced emission" (AIEE) mechanism. PMID:25207523

Shiragami, Tsutomu; Nakamura, Yoko; Matsumoto, Jin; Otsuki, Masashi; Yasuda, Masahide



Lithium-sulfur batteries based on nitrogen-doped carbon and ionic liquid electrolyte  

SciTech Connect

Nitrogen-doped mesoporous carbon (NC) and sulfur were used to prepare an NC/S composite cathode, which was evaluated in an ionic liquid electrolyte of 0.5 M lithium bis(trifluoromethane sulfonyl)imide (LiTFSI) in methylpropylpyrrolidinium bis(trifluoromethane sulfonyl)imide (MPPY.TFSI) by cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), and cycle testing. To facilitate the comparison, a C/S composite based on activated carbon (AC) without nitrogen doping was also fabricated under the same conditions as those for the NC/S composite. Compared with the AC/S composite, the NC/S composite showed enhanced activity toward sulfur reduction, as evidenced by the early onset sulfur reduction potential, higher redox current density in the CV test, and faster charge transfer kinetics as indicated by EIS measurement. At room temperature under a current density of 84 mA g-1 (C/20), the battery based on the NC/S composite exhibited higher discharge potential and an initial capacity of 1420 mAh g-1 whereas that based on the AC/S composite showed lower discharge potential and an initial capacity of 1120 mAh g-1. Both batteries showed similar capacity fading with cycling due to the intrinsic polysulfide solubility and the polysulfide shuttle mechanism; the capacity fading can be improved by further modification of the cathode.

Sun, Xiao-Guang [ORNL; Wang, Xiqing [ORNL; Mayes, Richard T [ORNL; Dai, Sheng [ORNL



Ionic liquid-assisted synthesis of Pt nanoparticles onto exfoliated graphite nanoplatelets for fuel cells.  


Exfoliated graphite nanoplatelets (GnP) has been investigated as an electrocatalyst support for fuel cell applications. GnP-supported Pt catalysts were synthesized by a microwave process in the presence of room temperature ionic liquids (RTILs). Thermal-oxidation resistance of GnP and GnP-supported Pt catalysts was studied by thermogravimetric analysis and compared with a variety of other carbon nanostructures: carbon black, graphite nanofiber, single- and multiwalled carbon nanotubes. GnP showed the best thermal-oxidative stability. The results obtained from X-ray diffraction, X-ray photoelectron spectroscopy, electrochemical testing, scanning and transmission electron microscopy showed that the RTIL synthesis method resulted in size reduction of Pt nanoparticle, improvement of Pt dispersion on GnP, and identification of the relationships between the mean size of Pt particles with increasing RTIL content. The interaction of Pt particles-GnP is stronger than that of a commercial Pt-CB, and the Pt/GnP catalysts prepared by this method have excellent electrocatalytic activity and stability for methanol oxidation. PMID:25036977

Do, Inhwan; Drzal, Lawrence T



Room temperature creep of high strength steels  

Microsoft Academic Search

The room-temperature creep behavior of three high strength steels has been investigated. Several parameters such as creep stress, loading rate, stress history and heat treatment has been altered and their influence on the low temperature creep has been reported. The primary creep in all three alloys agreed well with the logarithmic creep law and the creep mechanism has been identified

A. Oehlert; A. Atrens



Room-temperature antiferromagnetic memory resistor  

NASA Astrophysics Data System (ADS)

The bistability of ordered spin states in ferromagnets provides the basis for magnetic memory functionality. The latest generation of magnetic random access memories rely on an efficient approach in which magnetic fields are replaced by electrical means for writing and reading the information in ferromagnets. This concept may eventually reduce the sensitivity of ferromagnets to magnetic field perturbations to being a weakness for data retention and the ferromagnetic stray fields to an obstacle for high-density memory integration. Here we report a room-temperature bistable antiferromagnetic (AFM) memory that produces negligible stray fields and is insensitive to strong magnetic fields. We use a resistor made of a FeRh AFM, which orders ferromagnetically roughly 100 K above room temperature, and therefore allows us to set different collective directions for the Fe moments by applied magnetic field. On cooling to room temperature, AFM order sets in with the direction of the AFM moments predetermined by the field and moment direction in the high-temperature ferromagnetic state. For electrical reading, we use an AFM analogue of the anisotropic magnetoresistance. Our microscopic theory modelling confirms that this archetypical spintronic effect, discovered more than 150 years ago in ferromagnets, is also present in AFMs. Our work demonstrates the feasibility of fabricating room-temperature spintronic memories with AFMs, which in turn expands the base of available magnetic materials for devices with properties that cannot be achieved with ferromagnets.

Marti, X.; Fina, I.; Frontera, C.; Liu, Jian; Wadley, P.; He, Q.; Paull, R. J.; Clarkson, J. D.; Kudrnovský, J.; Turek, I.; Kuneš, J.; Yi, D.; Chu, J.-H.; Nelson, C. T.; You, L.; Arenholz, E.; Salahuddin, S.; Fontcuberta, J.; Jungwirth, T.; Ramesh, R.