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1

IMPROVED SYNTHESIS OF ROOM TEMPERATURE IONIC LIQUIDS  

EPA Science Inventory

Room temperature ionic liquids (RTILs), molten salts comprised of N-alkylimidazolium cations and various anions, have received significant attention due to their commercial potential in a variety of chemical applications especially as substitutes for conventional volatile organic...

2

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

1997-01-01

3

Electrochemical Generation of Superoxide in Room-Temperature Ionic Liquids  

E-print Network

Electrochemical 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 aprotic solvents such as dimethyl formamide and acetonitrile. However, ionic liquids are nonvolatile

Weidner, John W.

4

Room-temperature ionic liquid battery electrolytes  

SciTech Connect

The 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 the ionic liquids have excellent characteristics, the chemical and electrochemical properties of desirable battery electrode materials are not well understood in these electrolytes. The research has focused on rechargeable electrodes and has included work on metallic lithium and sodium anodes in buffered neutral chloroaluminate melts, graphite-intercalation electrodes in neutral chloroaluminate and non-chloroaluminate melts, and silane-imidazole polymeric cathodes in acidic chloroaluminate melts. This paper will provide an overview of the research in these areas.

Carlin, R.T.; Fuller, J. [Covalent Associates, Inc., Woburn, MA (United States)

1997-12-01

5

Room temperature ionic liquids and their mixtures—a review  

Microsoft Academic Search

Room temperature ionic liquids are salts that are liquid at room temperature and their use as catalysts and catalytic support has been studied extensively. They are also being considered as “green solvents” for various separation processes. Recent measurements reported on the properties of pure ionic liquids and their mixtures, including gas and liquid solubility in common organic solvents will be

K. N Marsh; J. A Boxall; R Lichtenthaler

2004-01-01

6

Are Room Temperature Ionic Liquids Dilute Electrolytes?  

E-print Network

An important question in understanding the structure of ionic liquids is whether ions are truly "free" and mobile which would correspond to a concentrated ionic melt, or are rather "bound" in ion pairs, that is a liquid of ion pairs with a small concentration of free ions. Recent surface force balance experiments from different groups have given conflicting answers to this question. We propose a simple model for the thermodynamics and kinetics of ion pairing in ionic liquids. Our model takes into account screened ion-ion, dipole-dipole and dipole-ion interactions in the mean field limit. The results of this model suggest that almost two thirds of the ions are free at any instant, and ion pairs have a short lifetime comparable to the characteristic timescale for diffusion. These results suggest that there is no particular thermodynamic or kinetic preference for ions residing in pairs. We therefore conclude that ionic liquids are concentrated, rather than dilute, electrolytes.

Lee, Alpha A; Perkin, Susan; Goriely, Alain

2014-01-01

7

Are Room Temperature Ionic Liquids Dilute Electrolytes?  

E-print Network

An important question in understanding the structure of ionic liquids is whether ions are truly "free" and mobile which would correspond to a concentrated ionic melt, or are rather "bound" in ion pairs, that is a liquid of ion pairs with a small concentration of free ions. Recent surface force balance experiments from different groups have given conflicting answers to this question. We propose a simple model for the thermodynamics and kinetics of ion pairing in ionic liquids. Our model takes into account screened ion-ion, dipole-dipole and dipole-ion interactions in the mean field limit. The results of this model suggest that almost two thirds of the ions are free at any instant, and ion pairs have a short lifetime comparable to the characteristic timescale for diffusion. These results suggest that there is no particular thermodynamic or kinetic preference for ions residing in pairs. We therefore conclude that ionic liquids are concentrated, rather than dilute, electrolytes.

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

2014-12-26

8

Structure of Ionic Liquids The Structure of a Room-Temperature Ionic  

E-print Network

Structure of Ionic Liquids The Structure of a Room-Temperature Ionic Liquid with and without Trace Tetrafluoroborate** Andrea Mele,* Chieu D. Tran, and Silvia H. De Paoli Lacerda Room temperature ionic liquids of a given cross peak in 1a (pure ionic liquid) and V=integrated volume of the same cross peak in the sample

Reid, Scott A.

9

Room temperature lithium polymer batteries based on ionic liquids  

Microsoft Academic Search

In this manuscript are reported the results of an investigation performed on rechargeable, all-solid-state, solvent-free, Li\\/LiFePO4 polymer batteries incorporating N-butyl-N-methyl-pyrrolidinium bis(trifluoromethanesulfonyl)imide, PYR14TFSI, ionic liquid (IL). The tests show clearly the beneficial effect due to the incorporation of ionic liquids on room temperature battery performance that, conversely, results extremely poor in IL-free lithium polymer batteries. The theoretical capacity is delivered at

G. B. Appetecchi; G. T. Kim; M. Montanino; F. Alessandrini; S. Passerini

2011-01-01

10

Room Temperature Ionic Liquids for Separating Organics from Produced Water  

Microsoft Academic Search

The distribution of polar organic compounds typical of water contaminants (organic acids, alcohols, and aromatic compounds) associated with oil and gas production was measured between water and nine hydrophobic, room?temperature ionic liquids. The ionic liquids used in this study were 1?butyl?3?methylimidazolium bistrifluoromethanesulfonylimide, 1?hexyl?3?methylimidazolium bistrifluoromethanesulfonylimide, 1?octyl?3?methylimidazolium bistrifluoromethanesulfonylimide, 1?butyl?3?methylimidazolium hexafluorophosphate, trihexyltetradecylphosphonium bistrifluoromethanesulfonylimide, 1?butyl?1?methyl?pyrrolidinium bistrifluoromethanesulfonylimide, trihexyltetradecylphosphonium dodecylbenzenesulfonate, tributyltetradecylphosphonium dodecylbenzenesulfonate, and trihexyltetradecylphosphonium methanesulfonate. Sensitivity

J. McFarlane; W. B. Ridenour; H. Luo; R. D. Hunt; D. W. DePaoli; R. X. Ren

2005-01-01

11

Application of room temperature ionic liquids to Li batteries  

Microsoft Academic Search

Novel electrolyte materials, room temperature ionic liquids (RTILs) were applied to the Li battery system and their characteristics in Li-metal batteries are discussed, partly reviewing authors work in the past. Quaternary ammonium (QA) cation-imide RTIL was focused on because of the excellent stability in cathodic environment of Li. Li\\/LiCoO2 cell performance and Li cycling efficiency using the selected QA-imide RTIL

Hikari Sakaebe; Hajime Matsumoto; Kuniaki Tatsumi

2007-01-01

12

Dissolution of cellulose in room temperature ionic liquids: anion dependence.  

PubMed

The dissolution of cellulosic biomass in room temperature ionic liquids (RTILs) is studied through free energy calculations of its monomer, viz., cellobiose, within a molecular dynamics simulation approach. The solvation free energy (SFE) of cellobiose in ionic liquids containing any of seven different anions has been calculated. The ranking of these liquids based on SFE compares well with experimental data on the solubility of cellulose. The dissolution is shown to be enthalpically dominated, which is correlated with the strength of intermolecular hydrogen bonding between cellobiose and the anions of the IL. Large entropic changes upon solvation in [CF3SO3](-) and [OAc](-) based ionic liquids have been explained in terms of the solvent-aided conformational flexibility of cellobiose. PMID:25535797

Payal, Rajdeep Singh; Bejagam, Karteek K; Mondal, Anirban; Balasubramanian, Sundaram

2015-01-29

13

Dynamics and structure of room temperature ionic liquids  

NASA Astrophysics Data System (ADS)

Room temperature ionic liquids (RTIL) are intrinsically interesting because they simultaneously have properties that are similar to organic liquids and liquid salts. In addition, RTILs are increasingly being considered for and used in technological applications. RTILs are usually composed of an organic cation and an inorganic anion. The organic cation, such as imidazolium, has alkyl chains of various lengths. The disorder in the liquid produced by the presence of the alkyl groups lowers the temperature for crystallization below room temperature and can also result in supercooling and glass formation rather than crystallization. The presence of the alkyl moieties also results in a segregation of the liquid into ionic and organic regions. In this article, experiments are presented that address the relationship between RTIL dynamics and structure. Time resolved fluorescence anisotropy measurements were employed to study the local environments in the organic and ionic regions of RTILs using a nonpolar chromophore that locates in the organic regions and an ionic chromophore that locates in the ionic regions. In the alkyl regions, the in plane and out of plane orientational friction coefficients change in different manners as the alkyl chains get longer. Both friction coefficients converge toward those of a long chain length hydrocarbon as the RTIL chains increase in length, which demonstrates that for sufficiently long alkyl chains the RTIL organic regions have properties similar to a hydrocarbon. However, putting Li+ in the ionic regions changes the friction coefficients in the alkyl regions, which demonstrates that changes of the ion structural organization influences the organization of the alkyl chains. Optical heterodyne detected optical Kerr effect (OHD-OKE) experiments were used to examine the orientational relaxation dynamics of RTILs over times scales of a hundred femtoseconds to a hundred nanoseconds. Detailed temperature dependent studies in the liquid and supercooled state and analysis using schematic mode coupling theory (MCT) show that RTILs have bulk liquid orientational relaxation dynamics that are indistinguishable in their nature from common nonpolar organic liquids that supercool. This behavior of the RTILs occurs in spite of the segregation into ionic and organic regions. However, when small amounts of water are added to RTILs at room temperature, novel dynamics are observed for the RTILs with long alkyl chains that have not been observed in OHD-OKE experiments on organic liquids. The results are interpreted as water induced structure in the ionic regions that causes the long alkyl chains to organize and 'lock up.' The dynamical measurements indicate that this lock up is involved in the formation of RTIL gels that occur over a narrow range of water concentrations.

Fayer, Michael D.

2014-11-01

14

Oligoether carboxylates: task-specific room-temperature ionic liquids.  

PubMed

Recently, a new family of ionic liquids based on oligoether carboxylates was introduced. 2,5,8,11-Tetraoxatridecan-13-oate (TOTO) was shown to form room-temperature ionic liquids (RTILs) even with small alkali ions such as lithium and sodium. However, the alkali TOTO salts suffer from their extremely high viscosities and relatively low conductivities. Therefore, we replaced the alkali cations by tetraalkylammonium (TAA) ions and studied the TOTO salts of tetraethyl- (TEA), tetrapropyl- (TPA), and tetrabutylammonium (TBA). In addition, the environmentally benign quaternary ammonium ion choline (Ch) was included in the series. All salts were found to be ionic liquids at ambient temperatures with a glass transition typically at around -60 °C. Viscosities, conductivities, solvent polarities, and Kamlet-Taft parameters were determined as a function of temperature. When using quaternary ammonium ions, the viscosities of the resulting TOTO ionic liquids are >600 times lower, whereas conductivities increase by a factor of up to 1000 compared with their alkali counterparts. Solvent polarities further reveal that choline and TAA cations yield TOTO ionic liquids that are more polar than those obtained with the, per se, highly polar sodium ion. Results are discussed in terms of ion-pairing and structure-breaking concepts with regard to a possible complexation ability of the TOTO anion. PMID:21682314

Klein, Regina; Zech, Oliver; Maurer, Eva; Kellermeier, Matthias; Kunz, Werner

2011-07-28

15

Chromatographic and spectroscopic methods for the determination of solvent properties of room temperature ionic liquids  

Microsoft Academic Search

Room temperature ionic liquids are novel solvents with favorable environmental and technical features. Synthetic routes to over 200 room temperature ionic liquids are known but for most ionic liquids physicochemical data are generally lacking or incomplete. Chromatographic and spectroscopic methods afford suitable tools for the study of solvation properties under conditions that approximate infinite dilution. Gas–liquid chromatography is suitable for

Colin F. Poole

2004-01-01

16

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

E-print Network

From molten salts to room temperature ionic liquids: Simulation studies on chloroaluminate systems chloride, which forms a room temperature ionic liquid EMI+ -AlCl- 4 . The structure yielded. INTRODUCTION When monovalent chloride salts are dissolved in liquid AlCl3, ionic liquids with low melting

Paris-Sud XI, Université de

17

Room temperature ionic liquids as replacements for conventional solvents – A review  

Microsoft Academic Search

Room temperature ionic liquids are salts that are liquids at ambient temperature. They are excellent solvents for a broad\\u000a range of polar organic compounds and they show partial miscibility with aromatic hydrocarbons. Typical room temperature ionic\\u000a liquids have a stable liquid range of over 300 K and have a very low vapor pressure at room temperature. Ionic liquids that\\u000a are

Kenneth N. Marsh; Alex Deev; Alex C. T. Wu; Emma Tran; A. Klamt

2002-01-01

18

The Influence of Lithium Cations on Dynamics and Structure of Room Temperature Ionic Liquids  

E-print Network

The Influence of Lithium Cations on Dynamics and Structure of Room Temperature Ionic Liquids ionic liquid (RTIL) 1-butyl-3-methylimida- zolium bis(trifluoromethyl)sulfonyl imide were studied the structure of the alkyl regions of the RTIL. I. INTRODUCTION Room temperature ionic liquids (RTIL) have

Fayer, Michael D.

19

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 ionic liquids (RTIL), such as 1-butyl-3- methylimidazolium hexafluorophosphate (BmImPF6), are salts

Fayer, Michael D.

20

Contracting cardiomyocytes in hydrophobic room-temperature ionic liquid  

SciTech Connect

Highlights: Black-Right-Pointing-Pointer Biocompatible room-temperature ionic liquid was applied on beating cardiomyocyte. Black-Right-Pointing-Pointer The lifetime of beating cardiomyocytes was depended on anion functional group. Black-Right-Pointing-Pointer A longer lifetime was recorded for no functional group on alkyl chain on their anion. Black-Right-Pointing-Pointer Amino group on alkyl chain and fluorine in anion induced fatal condition changes. Black-Right-Pointing-Pointer We reported liquid electrolyte interface to stimulate cardiomyocytes. -- Abstract: Room-temperature ionic liquids (RTILs) are drawing attention as a new class of nonaqueous solvents to replace organic and aqueous solvents for chemical processes in the liquid phase at room temperature. The RTILs are notable for their characteristics of nonvolatility, extremely low vapor pressure, electric conductivity, and incombustibility. These distinguished properties of RTILs have brought attention to them in applications with biological cells and tissue in vacuum environment for scanning electron microscopy, and in microfluidic devices for micro-total analysis system (micro-TAS). Habitable RTILs could increase capability of nonaqueous micro-TAS for living cells. Some RTILs seemed to have the capability to replace water in biological applications. However, these RTILs had been applied to just supplemental additives for biocompatible test, to fixed cells as a substitute for an aqueous solution, and to simple molecules. None of RTILs in which directly soaks a living cell culture. Therefore, we demonstrated the design of RTILs for a living cell culture and a liquid electrolyte to stimulate contracting cardiomyocytes using the RTILs. We assessed the effect of RTILs on the cardiomyocytes using the beating lifetime to compare the applicability of RTILs for biological applications. Frequent spontaneous contractions of cardiomyocytes were confirmed in amino acid anion RTILs [P{sub 8,8,8,8}][Leu] and [P{sub 8,8,8,8}][Ala], phosphoric acid derivatives [P{sub 8,8,8,8}][MeO(H)PO{sub 2}], and [P{sub 8,8,8,8}][C{sub 7}CO{sub 2}]. The anion type of RTILs had influence on applicable characteristics for the contracting cardiomyocyte. This result suggested the possibility for biocompatible design of hydrophobic group RTILs to achieve biological applications with living cells.

Hoshino, Takayuki [Department of Mechanical Engineering, Osaka University, 2-1 Yamadaoka, Suita, Osaka 565-0871 (Japan) [Department of Mechanical Engineering, Osaka University, 2-1 Yamadaoka, Suita, Osaka 565-0871 (Japan); Department of Bio-Application and System Engineering, Tokyo University of Agriculture and Technology, 2-24-16 Naka-cho, Koganei-shi, Tokyo 184-8588 (Japan); Fujita, Kyoko [Department of Biotechnology, Tokyo University of Agriculture and Technology, 2-24-16 Naka-cho, Koganei-shi, Tokyo 184-8588 (Japan)] [Department of Biotechnology, Tokyo University of Agriculture and Technology, 2-24-16 Naka-cho, Koganei-shi, Tokyo 184-8588 (Japan); Higashi, Ayako; Sakiyama, Keiko [Department of Bio-Application and System Engineering, Tokyo University of Agriculture and Technology, 2-24-16 Naka-cho, Koganei-shi, Tokyo 184-8588 (Japan)] [Department of Bio-Application and System Engineering, Tokyo University of Agriculture and Technology, 2-24-16 Naka-cho, Koganei-shi, Tokyo 184-8588 (Japan); Ohno, Hiroyuki [Department of Biotechnology, Tokyo University of Agriculture and Technology, 2-24-16 Naka-cho, Koganei-shi, Tokyo 184-8588 (Japan)] [Department of Biotechnology, Tokyo University of Agriculture and Technology, 2-24-16 Naka-cho, Koganei-shi, Tokyo 184-8588 (Japan); Morishima, Keisuke, E-mail: morishima@mech.eng.osaka-u.ac.jp [Department of Mechanical Engineering, Osaka University, 2-1 Yamadaoka, Suita, Osaka 565-0871 (Japan) [Department of Mechanical Engineering, Osaka University, 2-1 Yamadaoka, Suita, Osaka 565-0871 (Japan); Department of Bio-Application and System Engineering, Tokyo University of Agriculture and Technology, 2-24-16 Naka-cho, Koganei-shi, Tokyo 184-8588 (Japan)

2012-10-19

21

Phosphonium chloromercurate room temperature ionic liquids of variable composition.  

PubMed

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

2013-12-16

22

Ultrafast solvation response in room temperature ionic liquids: Possible origin and importance of the collective and the nearest neighbour solvent  

E-print Network

Ultrafast solvation response in room temperature ionic liquids: Possible origin and importance OF CHEMICAL PHYSICS 137, 114501 (2012) Ultrafast solvation response in room temperature ionic liquids temperature ionic liquids (RTILs) have revealed multi-exponential dynamics with ultrafast solvation timescale

Biswas, Ranjit

23

Pronounced structure in confined aprotic room-temperature ionic liquids.  

PubMed

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

2009-05-21

24

Synthesis of tin nanocrystals in room temperature ionic liquids.  

PubMed

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

2014-12-28

25

Mesophases in Nearly 2D Room-Temperature Ionic Liquids  

E-print Network

Computer simulations of (i) a [C12mim][Tf2N] film of nanometric thickness squeezed at kbar pressure by a piecewise parabolic confining potential reveal a mesoscopic in-plane density and composition modulation reminiscent of mesophases seen in 3D samples of the same room-temperature ionic liquid (RTIL). Near 2D confinement, enforced by a high normal load, relatively long aliphatic chains are strictly required for the mesophase formation, as confirmed by computations for two related systems made of (ii) the same [C12mim][Tf2N] adsorbed at a neutral solid surface and (iii) a shorter-chain RTIL ([C4mim][Tf2N]) trapped in the potential well of part i. No in-plane modulation is seen for ii and iii. In case ii, the optimal arrangement of charge and neutral tails is achieved by layering parallel to the surface, while, in case iii, weaker dispersion and packing interactions are unable to bring aliphatic tails together into mesoscopic islands, against overwhelming entropy and Coulomb forces. The onset of in-plane mesophases could greatly affect the properties of long-chain RTILs used as lubricants.

N. Manini; M. Cesaratto; M. G. Del Popolo; P. Ballone

2009-10-27

26

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.

2011-01-01

27

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

E-print Network

Room Temperature Ionic Liquid-Lithium Salt Mixtures: Optical Kerr Effect Dynamical Measurements to ionic liquids causes an increase in viscosity and a decrease in ionic mobility that hinders relaxation, caused by the addition of lithium bis(trifluoromethylsulfonyl)imide to the ionic liquid 1-butyl-3

Fayer, Michael D.

28

Dipolar Solvation Dynamics in Room Temperature Ionic Liquids: An Effective Medium Calculation Using Dielectric Relaxation Data  

E-print Network

Dipolar Solvation Dynamics in Room Temperature Ionic Liquids: An Effective Medium Calculation Using to a laser-excited probe molecule in an ionic liquid is approximated by that in an effective dipolar medium, no probe dependence has been found for the average solvation times in these ionic liquids. In addition

Biswas, Ranjit

29

Electrochemical Windows of Room-Temperature Ionic Liquids from Molecular Dynamics and Density Functional Theory Calculations  

E-print Network

We investigated the cathodic and anodic limits of six room-temperature ionic liquids (ILs) formed from a combination of two common cations, 1-butyl-3-methylimidazolium (BMIM) and N,N-propylmethylpyrrolidinium (P13), and ...

Ong, Shyue Ping

30

Heparin-cellulose-charcoal composites for drug detoxification prepared using room temperature ionic liquids.  

PubMed

We report novel heparin-cellulose-charcoal composites prepared using room temperature ionic liquids (RTILs) to enhance the biocompatibility and blood compatibility of activated charcoal beads while decreasing the size of their active pores. PMID:18931773

Park, Tae-Joon; Lee, Sang-Hyun; Simmons, Trevor J; Martin, Jeffrey G; Mousa, Shaker A; Snezhkova, Elisaveta A; Sarnatskaya, Veronika V; Nikolaev, Vladimir G; Linhardt, Robert J

2008-10-28

31

Formic acid electro-synthesis from carbon dioxide in a room temperature ionic liquid.  

PubMed

The novel synthesis of formic acid has been achieved in a room temperature ionic liquid via the reaction of electro-activated carbon dioxide and protons on pre-anodised platinum. Only mild reaction conditions of room temperature and 1 atm CO(2) were used. This work highlights the effect of pre-anodisation on Pt surfaces. PMID:22622393

Martindale, Benjamin C M; Compton, Richard G

2012-07-01

32

The room temperature ionic liquid 1-ethyl-3-methylimidazolium tetrafluoroborate: Electrochemical couples and physical properties  

Microsoft Academic Search

Room temperature molten salts composed of the 1-ethyl-3-methylimidazolium cation and a chloroaluminate anion have received much attention for use in a variety of commercial applications such as batteries, photovoltaics, metal deposition, and capacitors. The room temperature ionic liquid 1-ethyl-3-methylimidazolium tetrafluoroborate (EMIBFâ) was demonstrated as a versatile electrolyte by examining three representative electrochemical couples: ferrocene and tetrathiafulvalene oxidations and lithium ion

Joan Fuller; R. T. Carlin; R. A. Osteryoung

1997-01-01

33

Static and transport properties of alkyltrimethylammonium cation-based room-temperature ionic liquids.  

PubMed

We have measured physicochemical properties of five alkyltrimethylammonium cation-based room-temperature ionic liquids and compared them with those obtained from computational methods. We have found that static properties (density and refractive index) and transport properties (ionic conductivity, self-diffusion coefficient, and viscosity) of these ionic liquids show close relations with the length of the alkyl chain. In particular, static properties obtained by experimental methods exhibit a trend complementary to that by computational methods (refractive index ? [polarizability/molar volume]). Moreover, the self-diffusion coefficient obtained by molecular dynamics (MD) simulation was consistent with the data obtained by the pulsed-gradient spin-echo nuclear magnetic resonance technique, which suggests that computational methods can be supplemental tools to predict physicochemical properties of room-temperature ionic liquids. PMID:24702446

Seki, Shiro; Tsuzuki, Seiji; Hayamizu, Kikuko; Serizawa, Nobuyuki; Ono, Shimpei; Takei, Katsuhito; Doi, Hiroyuki; Umebayashi, Yasuhiro

2014-05-01

34

Evaluation of a Ag?Ag + reference electrode for use in room temperature ionic liquids  

Microsoft Academic Search

Interest continues to grow in the use of room temperature ionic liquids (RTILs) as electrolytes in a range of electrochemical applications, such as lithium batteries, supercapacitors and dye-sensitized solar cells. Underpinning this growth, investigations into the electrochemical behaviour of RTILs and RTIL-based systems rely on accurate and precise data on the potentials of redox processes. While most researchers have continued

G. A. Snook; A. S. Best; A. G. Pandolfo; A. F. Hollenkamp

2006-01-01

35

New room temperature ionic liquids with interesting ecotoxicological and antimicrobial properties  

Microsoft Academic Search

A new set of room temperature ionic liquids (RTIL), tetrabutylammonium (TBA) salts: formate, acetate, propionate, butyrate, benzoate, nitrobenzoate, cinnamate, salicylate, sulfanilate, linoleate, and oleate, were prepared by neutralization of tetrabutylammonium hydroxide (TBA OH) and the corresponding acid. The compounds showed interesting chemical and biological properties. They are soluble in water and organic solvents producing conducting solutions and are effective against

Salman M. Saadeh; Zeyad Yasseen; Fadel A. Sharif; Hazem M. Abu Shawish

2009-01-01

36

Study on the reaction of chlorophenols in room temperature ionic liquids with ionizing radiation  

Microsoft Academic Search

The effects of cations and anions of room temperature ionic liquids (RTILs) on the decomposition of chlorophenols and formation of phenol were investigated by gamma and pulse radiolyses. Absorption bands were observed for aliphatic RTILs just after pulsed electron irradiation, and were assigned as solvated electrons. The decomposition yield of chlorophenol (CP), G(-CP), and the formation yield of phenol, G(Phenol),

Atsushi Kimura; Mitsumasa Taguchi; Takafumi Kondoh; Jinfeng Yang; Yoichi Yoshida; Koichi Hirota

2008-01-01

37

Aromatic iodination using N-iodosaccharin in room temperature ionic liquids  

Microsoft Academic Search

More reactive iodination conditions have been developed that combine the use of room temperature ionic liquids with N-iodosaccharin. Using these reaction conditions, even very modestly activated arenes such as toluene can be iodinated in good yield under very mild conditions.

Lindsey Bailey; Scott T. Handy

2011-01-01

38

Room temperature ionic liquids (RTILs): A new and versatile platform for cellulose processing and derivatization  

Microsoft Academic Search

Recent studies on the application of room temperature ionic liquids (RTILs) in cellulose chemistry have made great progresses. This has been providing a new and versatile platform for the wide utilization of cellulose resources and creation of novel functional materials. In this paper, the research progress in the field of dissolution, regeneration and derivatization of cellulose with RTILs are reviewed.

Yan Cao; Jin Wu; Jun Zhang; Huiquan Li; Yi Zhang; Jiasong He

2009-01-01

39

Bronsted acidic room temperature ionic liquids derived from N, N-dimethylformamide and similar protophilic amides.  

SciTech Connect

We herein describe a convenient and efficient one-pot route to a new family of cost-effective, highly proton conductive room temperature ionic liquids based on N,N-dimethylformamide and structural analogues thereof, thereby opening up potential in the fuel cell industry and other areas.

Huang, Jing-Fang [ORNL; Baker, Gary A [ORNL; Luo, Huimin [ORNL; Hong, Kunlun [ORNL; Li, Qing [ORNL; Bjerrum, Neils [University of Denmark; Dai, Sheng [ORNL

2006-01-01

40

Fast diffusion in a room-temperature ionic liquid confined in mesoporous carbon  

SciTech Connect

We report a quasielastic neutron scattering study in the temperature range of 290 to 350 K of a room temperature ionic liquid, [bmim+][Tf2N-], in the bulk form and confined in the 8.8 2.1 nm diameter pores of a mesoporous carbon matrix. In both bulk and confined liquids, our measurements, which are sensitive to the dynamics of the hydrogen-bearing cations, detect two distinct relaxation processes related to the diffusion of the cations. We have found that the cations that do not become immobilized near the pore walls exhibit an enhanced rather than suppressed diffusivity compared to the cation diffusivity in bulk liquid. Our results provide first experimental observation of molecular diffusion in a room temperature ionic liquid in confinement which is faster than diffusion in the bulk liquid.

Mamontov, Eugene [ORNL; Wesolowski, David J [ORNL; Fulvio, Pasquale F [ORNL; Dai, Sheng [ORNL

2012-01-01

41

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

SciTech Connect

A new solvent extraction process for separation of cesium-137 and strontium-90 from high-level wastes based on room-temperature ionic liquids has been studied. Room-temperature ionic liquids that are liquid at ambient temperatures can act as solvents for a broad spectrum of chemical species. A very unique intrinsic property of these melts is that they consist only of ions and that they can be made hydrophobic. The dual properties of these new ionic liquids make them efficient solvents for the extraction of ionic species from aqueous solutions. In this presentation, we will discuss our recent results on the solvent extraction of Na+, K+, Cs+ and Sr2+ by ionic liquids containing calix[4]arene-bis(tert-octylbenzo-crown-6)(BoBcalixC6) and dicyclohexano-18-crown-6 (DCH18C6). We will also present the synthesis of several new DCH18C6 derivatives with one of the oxygen atoms replaced by an azo group. With these new crown ethers, we are able to recycle crown ethers after the extraction experiments for metal cations in ionic liquids by pH modulation.

Luo, Huimin; Dai, Sheng

2003-09-10

42

Transport properties of room temperature ionic liquids from classical molecular dynamics  

E-print Network

Room Temperature Ionic Liquids (RTILs) have attracted much of the attention of the scientific community in the past decade due the their novel and highly customizable properties. Nonetheless their high viscosities pose serious limitations to the use of RTILs in practical applications. To elucidate some of the physical aspects behind transport properties of RTILs, extensive classical molecular dynamics (MD) calculations are reported. Bulk viscosities and ionic conductivities of butyl-methyl-imidazole based RTILs are presented over a wide range of temperatures. The dependence of the properties of the liquids on simulation parameters, e.g. system size effects and choice of the interaction potential, is analyzed.

Oliviero Andreussi; Nicola Marzari

2012-03-24

43

Transport properties of room temperature ionic liquids from classical molecular dynamics  

E-print Network

Room Temperature Ionic Liquids (RTILs) have attracted much of the attention of the scientific community in the past decade due the their novel and highly customizable properties. Nonetheless their high viscosities pose serious limitations to the use of RTILs in practical applications. To elucidate some of the physical aspects behind transport properties of RTILs, extensive classical molecular dynamics (MD) calculations are reported. Bulk viscosities and ionic conductivities of butyl-methyl-imidazole based RTILs are presented over a wide range of temperatures. The dependence of the properties of the liquids on simulation parameters, e.g. system size effects and choice of the interaction potential, is analyzed.

Andreussi, Oliviero

2012-01-01

44

Li\\/LiFePO 4 batteries with room temperature ionic liquid as electrolyte  

Microsoft Academic Search

Room temperature ionic liquid (RTIL) was prepared on basis of N-methyl-N-butylpiperidinium bis(trifluoromethanesulfonyl)imide (PP14TFSI), which showed a wide electrochemical window (?0.1–5.2V vs. Li+\\/Li) and is theoretically feasible as an electrolyte for batteries with metallic Li as anodes. The addition of vinylene carbonate (VC) improved the compatibility of PP14TFSI-based electrolyte towards lithium anodes and enhanced the formation of solid electrolyte interphase film

J. Jin; H. H. Li; J. P. Wei; X. K. Bian; Z. Zhou; J. Yan

2009-01-01

45

UV-cured polymer electrolytes encompassing hydrophobic room temperature ionic liquid for lithium batteries  

Microsoft Academic Search

We demonstrate herewith the application of in situ one-shot free radical photo-polymerisation (UV-curing) process to incorporate room temperature ionic liquids (RTILs) into polymer membranes which can be used as electrolytes for lithium-based batteries. The reactive formulation for the preparation of the polymer membranes was based on a dimethacrylic oligomer (BEMA). The polymer electrolyte membranes were synthesized by UV radiating a

C. Gerbaldi; J. R. Nair; Shahzada Ahmad; G. Meligrana; R. Bongiovanni; S. Bodoardo; N. Penazzi

2010-01-01

46

Application of nonflammable electrolyte with room temperature ionic liquids (RTILs) for lithium-ion cells  

Microsoft Academic Search

A mixture of flammable organic solvent and nonflammable room temperature ionic liquid (RTIL) has been investigated as a new concept electrolyte to improve the safety of lithium-ion cells. This study focused on the use of N-methyl-N-propylpiperidinium bis (trifluoromethanesulfonyl) imide (PP13-TFSI) as the RTIL for the flame-retardant additive. It was found that a carbon negative electrode, both graphite and hard carbon,

Hiroe Nakagawa; Yukiko Fujino; Suguru Kozono; Yoshihiro Katayama; Toshiyuki Nukuda; Hikari Sakaebe; Hajime Matsumoto; Kuniaki Tatsumi

2007-01-01

47

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.

2014-01-01

48

Analytical applications of room-temperature ionic liquids: A review of recent efforts  

Microsoft Academic Search

Room-temperature ionic liquids (RTILs) are solvents that may have great potential in chemical analysis. Recent surge in the number of publications\\/reports\\/books\\/monographs clearly indicate an increasing interest of scientific and engineering community toward these exciting and unique solvents. Consequently, a variety of analytical applications of RTILs have started to emerge. This review presents an account of some of the recent reports

Siddharth Pandey

2006-01-01

49

Sonochemistry and Sonoluminescence of Room-Temperature Ionic Liquids James D. Oxley, Tanya Prozorov, and Kenneth S. Suslick*  

E-print Network

Sonochemistry and Sonoluminescence of Room-Temperature Ionic Liquids James D. Oxley, Tanya Prozorov on such ionic liquids. We report here the sonochemical and sonoluminescent properties of several ionic liquids. Sonochemistry and sonoluminescence are a result of acoustic cavitation: the formation, growth, and implosive

Suslick, Kenneth S.

50

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

E-print Network

-Temperature Ionic Liquids by the Transient Grating Technique Clifford Frez* and Gerald J. Diebold Department measurements of thermal diffusivity of several room-temperature ionic liquids (RTILs) using the transient grating method. Measurements are carried out using ionic liquids with small concentrations of an inert dye

Reid, Scott A.

51

DEVELOPMENT OF ROOM TEMPERATURE IONIC LIQUIDS FOR APPLICATIONS IN ACTINIDE CHEMISTRY  

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.

W. OLDHAM; D. COSTA; W. SMITH

2001-05-01

52

Room temperature imidazolium ionic liquid: a solvent for extraction of carbamates prior to liquid chromatographic analysis.  

PubMed

A simple and rapid method for preconcentration of carbamate insecticides, including methomyl, propoxur, carbofuran, carbaryl, isoprocarb, methiocarb and promecarb, has been developed. It was based on a liquid-liquid microextraction using a [C(4)MIM][PF(6)] room temperature ionic liquid as an extraction solvent prior to analysis by high performance liquid chromatography with UV detection. Experimental parameters affecting the extraction performance, such as the volumes of sample, extractant and dissolving solvent, and extraction time, were studied. Under the selected conditions, the enrichment factors in the range between 10 and 25 could be achieved with the limit of detection in the range of 2-40 ?g L(-1), and with the relative standard deviations of lower than 0.6 and 10.2% for retention time and peak area, respectively. The proposed method offers advantages in reduction of the exposure danger to toxic solvents used in the conventional liquid-liquid extraction, simplicity of the extraction processes, rapidity, and sensitivity enhancement. The method was demonstrated to apply to the analysis of fruit and natural surface water samples. PMID:21641434

Vichapong, Jitlada; Burakham, Rodjana; Srijaranai, Supalax; Grudpan, Kate

2011-06-15

53

Supported Room Temperature Ionic Liquid Membranes for CO{sub 2}/CH{sub 4} Separation  

SciTech Connect

Room temperature ionic liquids (RTILs) are organic salts which are liquid at or around room temperature. These compounds exhibit many outstanding physical properties such as great thermal stability and no measurable vapor pressure. In this work supported ionic liquid membranes (SILMs) were prepared by impregnating pores of ?-alumina inorganic supports with various ionic liquids. In addition to membranes prepared with pure RTILs we were able to synthesize membranes with RTIL mixtures using 1-aminopyridinium iodide dissolved in 1-butyl-4-methylpyridinium tetrafluoroborate or methyltrioctylammonium bis(trifluoromethylsulfonyl)imide. This combination of an RTIL with an organic salt containing an amine group dramatically improved the membrane separation properties. The SILMs displayed CO{sub 2} permeance on the order of 5 × 10{sup ?10} to 5 × 10{sup ?9} mol m{sup ?2} s{sup ?1} Pa{sup ?1} combined with CO{sub 2}/CH{sub 4} selectivity of 5–30. Although these values are comparable with the current systems for CO{sub 2} purification, CO{sub 2} permeance is still rather low for these compounds.

Iarikov, D. D.; Hacarlioglu, P.; Oyama, S. T.

2011-01-01

54

Benzyl-Functionalized Room Temperature Ionic Liquids for CO2/N2 Separation  

SciTech Connect

In this work, three classes of room temperature ionic liquids (RTILs), including imidazolium, pyridinium, and pyrrolidinium ionic liquids with a benzyl group appended to the cation, were synthesized and tested for their performance in separating CO{sub 2} and N{sub 2}. All RTILs contained the bis(trifluoromethylsulfonyl)imide anion, permitting us to distinguish the impact of the benzyl moiety attached to the cation on gas separation performance. In general, the attachment of the benzyl group increased the viscosity of the ionic liquid compared with the unfunctionalized analogs and decreased the CO{sub 2} permeability. However, all of the benzyl-modified ionic liquids exhibited enhanced CO{sub 2}/N{sub 2} selectivities compared with alkyl-based ionic liquids, with values ranging from 22.0 to 33.1. In addition, CO{sub 2} solubilities in the form of Henry's constants were also measured and compared with unfunctionalized analogs. Results of the membrane performance tests and CO{sub 2} solubility measurements demonstrate that the benzyl-functionalized RTILs have significant potential for use in the separation of carbon dioxide from combustion products.

Mahurin, Shannon Mark [ORNL; Dai, Thomas N [ORNL; Yeary, Joshua S [ORNL; Luo, Huimin [ORNL; Dai, Sheng [ORNL

2011-01-01

55

Electrospun polymer membrane activated with room temperature ionic liquid: Novel polymer electrolytes for lithium batteries  

Microsoft Academic Search

A new class of polymer electrolytes (PEs) based on an electrospun polymer membrane incorporating a room-temperature ionic liquid (RTIL) has been prepared and evaluated for suitability in lithium cells. The electrospun poly(vinylidene fluoride-co-hexafluoropropylene) P(VdF-HFP) membrane is activated with a 0.5M solution of LiTFSI in 1-butyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide (BMITFSI) or a 0.5M solution of LiBF4 in 1-butyl-3-methylimidazolium tetrafluoroborate (BMIBF4). The resulting PEs

Gouri Cheruvally; Jae-Kwang Kim; Jae-Won Choi; Jou-Hyeon Ahn; Yong-Jo Shin; James Manuel; Prasanth Raghavan; Ki-Won Kim; Hyo-Jun Ahn; Doo Seong Choi; Choong Eui Song

2007-01-01

56

Equilibrium and dynamic charge storage in nanopores with room temperature ionic liquids  

NASA Astrophysics Data System (ADS)

Electrochemical capacitors store electrical energy physically in the electrical double layers at the electrode/electrolyte interfaces. In spite of their high power density and extraordinary cyclability, the widespread deployment of electrochemical capacitors is limited by their moderate energy density. The current surge in interest in electrochemical capacitors is driven by recent breakthroughs in developing novel electrode and electrolyte materials. In particular, electrodes featuring sub-nanometer pores and room-temperature ionic liquids are promising materials for next-generation electrochemical capacitors. To realize the full potential of these materials, a basic understanding of the charge storage mechanisms in them is essential. In this dissertation, using atomistic simulations, we investigated the charge storage in sub-nanometer pores using room-temperature ionic liquids as electrolytes. These simulations of the equilibrium charge storage in slit-shaped nanopores in contact with room-temperature ionic liquids showed that the capacitance of the nanopores exhibits a U-shaped scaling behavior in pores with width from 0.75 to 1.26 nm. The left branch of the capacitance scaling curve directly corresponds to the anomalous capacitance increase and thus confirms prior experimental observations. The right branch of the curve indirectly agrees with experimental findings that so far have received little attention. We also found that the charge storage in sub-nanometer pores follows a distinct voltage dependent behavior. At low voltages, charge storage is achieved by swapping co-ions in the pore with counter-ions in the bulk electrolytes. As voltage increases, further charge storage is due mainly to the removal of co-ions from the pore, leading to a capacitance increase. The capacitance eventually reaches a maximum when all co-ions are expelled from the pore. At even higher electrode voltages, additional charge storage is realized by counter-ion insertion into the pore, accompanied by a reduction of capacitance. The molecular origins of these phenomena were elucidated by a new theoretical framework we developed specifically for the charge storage in nanopores using solvent-free electrolytes. These simulations of the charging dynamics of sub-nanometer pores in contact with room-temperature ionic liquids showed that the charging of ionophilic pores, of width comparable to the size of ion, is a diffusive process. Such a process is often accompanied by overfilling and followed by de-filling. In sharp contrast to conventional expectations, charging is fast because ion diffusion during charging can be an order of magnitude faster than in the bulk, and charging itself is accelerated by the onset of collective modes. Further acceleration can be achieved using ionophobic pores by eliminating overfilling/de-filling and thus leading to charging behavior qualitatively different from that in conventional, ionophilic pores. Overall, our studies indicated that electrodes with sub-nanometer pores and room-temperature ionic liquids can potentially enable the development of electrochemical capacitors with concurrently high power and energy densities. The fundamental insights gained in our studies help guide the rational design and optimization of these materials to realize their full potentials.

Wu, Peng

57

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

E-print Network

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-AlCl 4. 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 Al2Cl 7- in small amounts. The calculated transport properties (diffusion coefficients, electrical conductivity and viscosity) of EMI-AlCl4 are in good ag...

Salanne, Mathieu; Seitsonen, Ari P; Madden, Paul A; Kirchner, Barbara; 10.1039/C1FD00053E

2013-01-01

58

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

2012-01-01

59

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

NASA Astrophysics Data System (ADS)

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.

Burba, Christopher M.; Frech, Roger

2011-04-01

60

Electrodeposition at room temperature of amorphous silicon and germanium nanowires in ionic liquid  

NASA Astrophysics Data System (ADS)

The electrodeposition at room temperature of silicon and germanium nanowires from the air- and water-stable ionic liquid 1-butyl-1-methylpyrrolidinium bis(trifluoromethanesulfonyl)imide (P1,4) containing SiCl4 as Si source or GeCl4 as Ge source is investigated by cyclic voltammetry. By using nanoporous polycarbonate membranes as templates, it is possible to reproducibly grow pure silicon and germanium nanowires of different diameters. The nanowires are composed of pure amorphous silicon or germanium. The nanowires have homogeneous cylindrical shape with a roughness of a few nanometres on the wire surfaces. The nanowires' diameters and lengths well match with the initial membrane characteristics. Preliminary photoluminescence experiments exhibit strong emission in the near infrared for the amorphous silicon nanowires.

Martineau, F.; Namur, K.; Mallet, J.; Delavoie, F.; Endres, F.; Troyon, M.; Molinari, M.

2009-11-01

61

EXAFS investigations of the mechanism of facilitated ion transfer into a room-temperature ionic liquid.  

SciTech Connect

The Sr(II)-crown ether complexes formed in a room-temperature ionic liquid (RTIL), 1-methyl-3-pentylimidazolium bis[(trifluoromethyl)sulfonyl]amide, have been studied by X-ray absorption fine structure measurements at the Sr K-edge. When a Sr(NO{sub 3}){sub 2}-crown ether complex is directly dissolved in a water-saturated RTIL, both nitrate ligands and the crown ether coordinate the Sr, as observed in a conventional two-phase water-octanol system. When the cationic Sr-crown ether complex is created in a two-phase water-RTIL system, however, only cationic Sr-crown ether complexes are observed in the RTIL phase. This difference in the coordination complexes arises from differences in the mechanism of cation extraction between the RTIL and conventional molecular organic solvents, a finding with important implications for synthesis, catalysis, and ion separations using two-phase water-RTIL systems.

Jensen, M. P.; Dzielawa, J. A.; Rickert, P.; Dietz, M. L.; Chemistry

2002-09-11

62

Ion transport and structural dynamics in homologous ammonium and phosphonium-based room temperature ionic liquids.  

PubMed

Charge transport and structural dynamics in a homologous pair of ammonium and phosphonium based room temperature ionic liquids (ILs) have been characterized over a wide temperature range using broadband dielectric spectroscopy and quasi-elastic light scattering spectroscopy. We have found that the ionic conductivity of the phosphonium based IL is significantly enhanced relative to the ammonium homolog, and this increase is primarily a result of a lower glass transition temperature and higher ion mobility. Additionally, these ILs exhibit pronounced secondary relaxations which are strongly influenced by the atomic identity of the cation charge center. While the secondary relaxation in the phosphonium IL has the expected Arrhenius temperature dependence characteristic of local beta relaxations, the corresponding relaxation process in the ammonium IL was found to exhibit a mildly non-Arrhenius temperature dependence in the measured temperature range-indicative of molecular cooperativity. These differences in both local and long-range molecular dynamics are a direct reflection of the subtly different inter-ionic interactions and mesoscale structures found in these homologous ILs. PMID:25725739

Griffin, Philip J; Holt, Adam P; Tsunashima, Katsuhiko; Sangoro, Joshua R; Kremer, Friedrich; Sokolov, Alexei P

2015-02-28

63

Ion transport and structural dynamics in homologous ammonium and phosphonium-based room temperature ionic liquids  

NASA Astrophysics Data System (ADS)

Charge transport and structural dynamics in a homologous pair of ammonium and phosphonium based room temperature ionic liquids (ILs) have been characterized over a wide temperature range using broadband dielectric spectroscopy and quasi-elastic light scattering spectroscopy. We have found that the ionic conductivity of the phosphonium based IL is significantly enhanced relative to the ammonium homolog, and this increase is primarily a result of a lower glass transition temperature and higher ion mobility. Additionally, these ILs exhibit pronounced secondary relaxations which are strongly influenced by the atomic identity of the cation charge center. While the secondary relaxation in the phosphonium IL has the expected Arrhenius temperature dependence characteristic of local beta relaxations, the corresponding relaxation process in the ammonium IL was found to exhibit a mildly non-Arrhenius temperature dependence in the measured temperature range—indicative of molecular cooperativity. These differences in both local and long-range molecular dynamics are a direct reflection of the subtly different inter-ionic interactions and mesoscale structures found in these homologous ILs.

Griffin, Philip J.; Holt, Adam P.; Tsunashima, Katsuhiko; Sangoro, Joshua R.; Kremer, Friedrich; Sokolov, Alexei P.

2015-02-01

64

Standard and absolute pKa scales of substituted benzoic acids in room temperature ionic liquids.  

PubMed

Equilibrium acidity (pKa) scales of 15 substituted benzoic acids in four room temperature ionic liquids (RTILs), BmimOTf, BmimNTf2, BmpyNTf2, and Bm2imNTf2, were established under standard conditions using a modified indicator overlapping method. The effect of homo hydrogen bonding on equilibrium acidity was calibrated, and the derived pKa values were evidenced to be free from ion-paring complication. Regression analyses demonstrated that all of the pKa scales obtained in four RTILs are linearly correlated to each other with an R value better than 0.996. These scales are also correlated well with the pKa values in DMSO and with the corresponding gas-phase acidities with regression coefficients of 0.993 and 0.992, respectively. In addition, both the cation and anion of the ionic liquids were found to play a role in affecting the acidity of carboxylic acid. PMID:24303780

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

2013-12-20

65

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 9.0.2.3 (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.

2009-11-25

66

Room-temperature ionic liquids enhanced green synthesis of ?-glycosyl 1-ester.  

PubMed

We herein report an efficient synthesis of ?-glycosyl 1-ester in room-temperature ionic liquids (RTILs) promoted via silver salt and quaternary ammonium salt (PTC) with good or excellent yields. All products were isolated exclusively as the ?-anomers. Four different RTILs, eight metal salts and four quaternary ammonium salts were screened in the glycosylation reaction. The synergistic effect of C6mim·OTf, Ag2O and tetrabutylammonium iodine gave the best results. Their promotion to the system was integral. Thorough study provided insight into the catalytic activity of ionic liquid structure, metal salts and quaternary ammonium salt to these reactions. It is worth mentioning that the yield of aliphatic compound 2,3,4,6-tetra-O-acetyl-?-d-galactopyranosyl butyrate (3l) was highly improved when using C6mim·OTf as solvent compared with the normal volatile solvents under the same catalysts. This green approach has been proved to be practical and compatible with a wide range from aliphatic to aromatic substrates. PMID:25704198

Cui, Yanli; Xu, Minghan; Yao, Weirong; Mao, Jianwei

2015-04-30

67

Electrochemical study and electrodeposition of manganese in the hydrophobic butylmethylpyrrolidinium bis((trifluoromethyl)sulfonyl)imide room-temperature ionic liquid  

Microsoft Academic Search

The electrochemistry of manganese was investigated at solid disk electrodes in the hydrophobic room-temperature ionic liquid butylmethylpyrrolidinium bis((trifluoromethyl)sulfonyl)imide (BuMePy-TFSI) by using staircase cyclic voltammetry and chronoamperometry. The Mn(II) species was introduced into the ionic liquid by anodic dissolution of the metallic manganese electrode. The reduction of Mn(II) ions at tungsten and platinum electrodes accompanies with nucleation mechanism and the coupled

Ming-Jay Deng; Po-Yu Chen; I-Wen Sun

2007-01-01

68

Ionic liquid pretreatment of poplar wood at room temperature: swelling and incorporation of nanoparticles  

SciTech Connect

Lignocellulosic biomass represents a potentially sustainable source of liquid fuels and commodity chemicals. It could satisfy the energy needs for transportation and electricity generation, while contributing substantially to carbon sequestration and limiting the accumulation of greenhouse gases in the atmosphere. Potential feedstocks are abundant and include crops, agricultural wastes, forest products, grasses, and algae. Among those feedstocks, wood is mainly constituted of three components: cellulose, hemicellulose, and lignin. The conversion process of lignocellulosic biomass typically consists of three steps: (1) pretreatment; (2) hydrolysis of cellulose and hemicellulose into fermentable sugars; and (3) fermentation of the sugars into liquid fuels (ethanol) and other commodity chemicals. The pretreatment step is necessary due to the complex structure of the plant cell wall and the chemical resistance of lignin. Most current pretreatments are energy-intensive and/or polluting. So it is imperative to develop new pretreatments that are economically viable and environmentally friendly. Recently, ionic liquids have attracted considerable interest, due to their ability to dissolve biopolymers, such as cellulose, lignin, native switchgrass, and others. Ionic liquids are also considered green solvents, since they have been successfully recycled at high yields for further use with limited efficiency loss. Also, a few microbial cellulases remain active at high ionic liquid concentration. However, all studies on the dissolution of wood in ionic liquids have been conducted so far at high temperatures, typically above 90 C. Development of alternative pretreatments at room temperature is desirable to eliminate the additional energy cost. In this study, thin sections of poplar wood were swollen at room temperature by a 3 h ionic liquid (1-ethyl-3-methylimidazolium acetate or EMIMAc) pretreatment. The pretreated sample was then exposed to an aqueous suspension of nanoparticles that resulted in the sample contraction and the deposition of nanoparticles onto the surface and embedded into the cell wall. To date, both silver and gold particles ranging in size from 40-100 nm have been incorporated into wood. Penetration of gold nanoparticles of 100 nm diameter in the cell walls was best confirmed by near-infrared confocal Raman microscopy, since the deposition of gold nanoparticles induces a significant enhancement of the Raman signal from the wood in their close proximity, an enhancement attributed to the surface-enhanced Raman effect (SERS). After rinsing with water, scanning electron microscopy (SEM) and Raman images of the same areas show that most nanoparticles remained on the pretreated sample. Raman images at different depths reveal that a significant number of nanoparticles were incorporated into the wood sample, at depths up to 4 {micro}m, or 40 times the diameter of the nanoparticles. Control experiments on an untreated wood sample resulted in the deposition of nanoparticles only at the surface and most nanoparticles were removed upon rinsing. This particle incorporation process enables the development of new pretreatments, since the nanoparticles have a high surface-to-volume ratio and could be chemically functionalized. Other potential applications for the incorporated nanoparticles include isotope tracing, catalysis, imaging agents, drug-delivery systems, energy-storage devices, and chemical sensors.

Lucas, Marcel [Los Alamos National Laboratory; Macdonald, Brian A [Los Alamos National Laboratory; Wagner, Gregory L [Los Alamos National Laboratory; Joyce, Steven A [Los Alamos National Laboratory; Rector, Kirk D [Los Alamos National Laboratory

2010-01-01

69

Magnetomotive room temperature dicationic ionic liquid: a new concept toward centrifuge-less dispersive liquid-liquid microextraction.  

PubMed

A new centrifuge-less dispersive liquid-liquid microextraction technique based on application of magnetomotive room temperature dicationic ionic liquid followed by electrothermal atomic absorption spectrometry (ETAAS) was developed for preconcentration and determination of trace amount of gold and silver in water and ore samples, for the first time. Magnetic ionic liquids not only have the excellent properties of ionic liquids but also exhibit strong response to an external magnetic field. These properties provide more advantages and potential application prospects for magnetic ionic liquids than conventional ones in the fields of extraction processes. In this work, thio-Michler's ketone (TMK) was used as chelating agent to form Ag/Au-TMK complexes. Several important factors affecting extraction efficiency including extraction time, rate of vortex agitator, pH of sample solution, concentration of the chelating agent, volume of ionic liquid as well as effects of interfering species were investigated and optimized. Under the optimal conditions, the limits of detection (LOD) were 3.2 and 7.3ngL(-1) with the preconcentration factors of 245 and 240 for Au and Ag, respectively. The precision values (RSD%, n=7) were 5.3% and 5.8% at the concentration level of 0.05?gL(-1) for Au and Ag, respectively. The relative recoveries for the spiked samples were in the acceptable range of 96-104.5%. The results demonstrated that except Hg(2+), no remarkable interferences are created by other various ions in the determination of Au and Ag, so that the tolerance limits (WIon/WAu or Ag) of major cations and anions were in the range of 250-1000. The validated method was successfully applied for the analysis of Au and Ag in some water and ore samples. PMID:25528072

Beiraghi, Asadollah; Shokri, Masood; Seidi, Shahram; Godajdar, Bijan Mombani

2015-01-01

70

Understanding and Optimizing Microemulsions with Magnetic Room Temperature Ionic Liquids (MRTILs).  

PubMed

Nonaqueous microemulsions containing the magnetic room temperature ionic liquid (MRTIL) bmimFeCl4 as polar phase were studied with respect to their macroscopic phase behavior and structure by means of small angle neutron scattering (SANS). The phase behavior was studied in detail for different alcohols as cosurfactant and different oils as nonpolar phase and mainly by varying the chain length of the used ionic surfactant (CnmimCl with n = 14, 16, 18). In general, phase behavior and structural ordering in the mesophases were found to be comparable to water systems where with increasing content of MRTIL the microemulsions seems to become less and less structured leading to a rough and softer interface with less long-range ordering. The extent of structuring increases with increasing chain length of the surfactant. However, the pure surfactant is not able to form microemulsions and a rather large amount of alcohol is required for stabilization, where the effectiveness of the alcohol increases with increasing chain length of the alcohol. From this comprehensive investigation systematic trends can be deduced in order to formulate correspondingly structured microemulsions with MRTIL as polar phase. PMID:25679318

Klee, Andreas; Prevost, Sylvain; Gasser, Urs; Gradzielski, Michael

2015-03-12

71

Ultrafast solvation dynamics and charge transfer reactions in room temperature ionic liquids.  

PubMed

Room temperature ionic liquids (ILs) are a new type of solvent with peculiar properties. ILs are usually composed of an anion and a bulky cation with one or more alkyl chains to decrease the melting point. These structural peculiarities lead to the high viscosity and the heterogeneity of ILs, which could affect chemical reactions. In the present perspective, we will first introduce the experimentally observed nature of the heterogeneous liquid structure and then introduce recent developments in the study on electron transfer (ET) and charge transfer (CT) reactions in relation with the solvation and the heterogeneity of ILs. Because of the high viscosity of ILs, diffusive solvation is expected to be slow which could be the rate-limiting factor for ET and CT processes. However, ILs could provide a unique reaction field depending on the location of the solute within the heterogeneous liquid structure and the reaction could be faster than that expected from the bulk viscosity due to the fast fluctuation of the local environment. PMID:24879120

Nagasawa, Yutaka; Miyasaka, Hiroshi

2014-07-14

72

Supported Phospholipid Bilayer Defects Created by a Cation or Anion of a Room-Temperature Ionic Liquid  

Technology Transfer Automated Retrieval System (TEKTRAN)

In this work, the independent effects on a supported phospholipid bilayer (SPB) caused by a cation and anion of a room-temperature ionic liquid (RT-IL) were studied via atomic force microscopy (AFM). The supported phospholipid bilayer was composed only of 1,2-dielaidoylphosphatidylcholine (DEPC) an...

73

Poly(ethylene oxide)-based polymer electrolyte incorporating room-temperature ionic liquid for lithium batteries  

Microsoft Academic Search

The effect of incorporating a room temperature ionic liquid, 1-butyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide (BMITFSI), in the polymer electrolyte (PE) based on poly(ethylene oxide)-(lithium bis(trifluoromethanesulfonyl) imide) [PEO-LiTFSI] was investigated. BMITFSI content was varied between 20 and 80 parts by weight (pbw) in 100 pbw of PEO-LiTFSI and the influence on ionic conductivity, electrochemical stability and interfacial properties on lithium electrode was studied. A remarkable

Jae-Won Choi; Gouri Cheruvally; Yeon-Hwa Kim; Jae-Kwang Kim; James Manuel; Prasanth Raghavan; Jou-Hyeon Ahn; Ki-Won Kim; Hyo-Jun Ahn; Doo Seong Choi; Choong Eui Song

2007-01-01

74

Fission-Product Separation Based on Room-Temperature Ionic Liquids  

SciTech Connect

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 extraction systems based on ionic liquids; (c) to develop efficient processes to recycle ionic liquids and crown ethers; and (d) to investigate chemical stabilities of ionic liquids under strong acid, strong base, and high-level-radiation conditions.

Luo, Huimin; Hussey, Charles L.

2005-09-30

75

Fission-Product Separation Based on Room-Temperature Ionic Liquids  

SciTech Connect

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 extraction systems based on ionic liquids; (c) to develop efficient processes to recycle ionic liquids and crown ethers; and (d) to investigate chemical stabilities of ionic liquids under strong acid, strong base, and high-level-radiation conditions.

Luo, Huimin

2006-11-15

76

Correlation between hydrogen bond basicity and acetylene solubility in room temperature ionic liquids.  

PubMed

Room temperature ionic liquids (RTILs) are proposed as the alternative solvents for the acetylene separation in ethylene generated from the naphtha cracking process. The solubility behavior of acetylene in RTILs was examined using a linear solvation energy relationship based on Kamlet-Taft solvent parameters including the hydrogen-bond acidity or donor ability (?), the hydrogen-bond basicity or acceptor ability (?), and the polarity/polarizability (?*). It is found that the solubility of acetylene linearly correlates with ? value and is almost independent of ? or ?*. The solubility of acetylene in RTILs increases with increasing hydrogen-bond acceptor (HBA) ability of the anion, but is little affected by the nature of the cation. Quantum mechanical calculations demonstrate that the acidic proton of acetylene specifically forms hydrogen bond with a basic oxygen atom on the anion of a RTIL. On the other hand, although C-H···? interaction is plausible, all optimized structures indicate that the acidic protons on the cation do not specifically associate with the ? cloud of acetylene. Thermodynamic analysis agrees well with the proposed correlation: the higher the ? value of a RTIL is, the more negative the enthalpy of acetylene absorption in the RTIL is. PMID:21218815

Palgunadi, Jelliarko; Hong, Sung Yun; Lee, Jin Kyu; Lee, Hyunjoo; Lee, Sang Deuk; Cheong, Minserk; Kim, Hoon Sik

2011-02-10

77

Islands of CdSe nanoparticles within Se nanofibers: a room temperature ionic liquid templated synthesis.  

PubMed

Herein, we present the formation of cadmium selenide (CdSe) islands embedded in a porous structure of entangled selenium (Se) nanofibers in the host matrix of a room temperature ionic liquid (RTIL). Electron beam irradiation has been employed to initiate the formation of the nanostructure while RTIL simultaneously played the role of a solvent, stabilizer and a shape guiding template for such morphology. UV-Vis absorption spectra of the irradiated samples exhibited an excitonic absorption feature in the visible region. The as-obtained nanostructure was characterized by TEM, SEM, XRD and EDX studies. Raman spectroscopic analysis of as-grown nanomaterials provided significant information about the formation of CdSe as well as distinct features of different forms of Se which further substantiated the results obtained from the above mentioned studies. Interestingly, an equivalent dose of ?-radiation led to the formation of predominantly nanosheet like structures in conjunction with a relatively homogeneous distribution of CdSe nanoparticles in the same matrix. The possible mechanism behind the obtained structures in these two methods has been proposed, and was rationalized in terms of dose rate difference and the existence of inherent heterogeneity in the structure of the IL. Finally, the implications of such a structure in various fields such as catalysis, sensing and photovoltaics have been discussed. PMID:24005564

Guleria, Apurav; Singh, Ajay K; Rath, Madhab C; Adhikari, Soumyakanti; Sarkar, Sisir K

2013-11-14

78

Rotational and translational diffusion of spin probes in room-temperature ionic liquids.  

PubMed

We have studied the rotational and translational diffusion of the spin probe 4-hydroxy-2,2,6,6-tetramethyl-1-piperidinyloxy (TEMPOL) in five imidazolium-based room-temperature ionic liquids (RTILs) and glycerol by means of X-band electron paramagnetic resonance (EPR) spectroscopy. Rotational correlation times and rate constants of intermolecular spin exchange have been determined by analysis of the EPR line shape at various temperatures and spin probe concentrations. The model of isotropic rotational diffusion cannot account for all spectral features of TEMPOL in all RTILs. In highly viscous RTILs, the rotational mobility of TEMPOL differs for different molecular axes. The translational diffusion coefficients have been calculated from spin exchange rate constants. To this end, line shape contributions stemming from Heisenberg exchange and from the electron-electron dipolar interaction have been separated based on their distinct temperature dependences. While the Debye-Stokes-Einstein law is found to apply for the rotational correlation times in all solvents studied, the dependence of the translational diffusion coefficients on the Stokes parameter T/? is nonlinear; i.e., deviations from the Stokes-Einstein law are observed. The effective activation energies of rotational diffusion are significantly larger than the corresponding values for translational motion. Effects of the identity of the RTIL cations and anions on the activation energies are discussed. PMID:22928518

Mladenova, Boryana Y; Chumakova, Natalia A; Pergushov, Vladimir I; Kokorin, Alexander I; Grampp, Günter; Kattnig, Daniel R

2012-10-11

79

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)

2011-04-14

80

Why Is the Partial Molar Volume of CO2 So Small When Dissolved in a Room Temperature Ionic Liquid? Structure and  

E-print Network

Why Is the Partial Molar Volume of CO2 So Small When Dissolved in a Room Temperature Ionic Liquid is dissolved in an ionic liquid, its partial molar volume is much smaller than that observed in most other and dynamics occurring across the boundary of the CO2 ionic liquid interface. We find that the liquid structure

Berne, Bruce J.

81

Synthesis and Characterization of Thiazolium-Based Room Temperature Ionic Liquids for Gas Separations  

SciTech Connect

A series of novel thiazolium-bis(triflamide) based ionic liquids has been synthesized and characterized. Physicochemical properties of the ionic liquids such as thermal stability, phase transitions, and infrared spectra were analysed and compared to the imidazolium-based congeners. Several unique classes of ancillary substitutions are examined with respect to impacts on overall structure, in addition to their carbon dioxide absorption properties in supported ionic-liquid membranes for gas separation.

Hillesheim, Patrick C [ORNL; Mahurin, Shannon Mark [ORNL; Fulvio, Pasquale F [ORNL; Yeary, Joshua S [ORNL; Oyola, Yatsandra [ORNL; Jiang, Deen [ORNL; Dai, Sheng [ORNL

2012-01-01

82

Electrochemical synthesis and in situ spectroelectrochemical characterization of poly(3,4-ethylenedioxythiophene) (PEDOT) in room temperature ionic liquids  

Microsoft Academic Search

The electrochemical synthesis and the charging–discharging reactions of poly(3,4-ethylenedioxythiophene) (PEDOT) in two room-temperature ionic liquids, 1-butyl-3-methyl-imidazolium tetrafluoroborate (BMIMBF4) and 1-butyl-3-methyl-imidazolium hexafluorophosphate (BMIMPF6) were studied with cyclic voltammetry, in situ attenuated total reflection Fourier transform infrared (ATR–FTIR) spectroscopy and by in situ UV–Vis spectroelectrochemistry. The structures of the films prepared in ionic liquids was compared to PEDOT films prepared in common

P. Damlin; C. Kvarnström; A. Ivaska

2004-01-01

83

Microscopic diffusion dynamics of silver complex-based room temperature ionic liquids probed by quasielastic neutron scattering  

SciTech Connect

Using quasielastic neutron scattering, we have probed the diffusion dynamics of the hydrogen-bearing cations of two different silver complex-derived room temperature ionic liquids, [Ag(propylamine)2+][Tf2N ] and [Ag(1-pentene)+][Tf2N ]. In the temperature range from 300 to 340 K, analysis of the scattering momentum transfer dependence of the data provides evidence for three distinct diffusion components. The slowest component describes the long-range cationic translational diffusion. We discuss a possible link between the diffusion parameters and the structural features of the cations comprising these two ionic liquids.

Mamontov, Eugene [ORNL; Baker, Gary A [ORNL; Luo, Huimin [ORNL; Dai, Sheng [ORNL

2011-01-01

84

Structure and dynamics of POPC bilayers in water solutions of room temperature ionic liquids  

NASA Astrophysics Data System (ADS)

Molecular dynamics simulations in the NPT ensemble have been carried out to investigate the effect of two room temperature ionic liquids (RTILs), on stacks of phospholipid bilayers in water. We consider RTIL compounds consisting of chloride ([bmim][Cl]) and hexafluorophosphate ([bmim][PF6]) salts of the 1-buthyl-3-methylimidazolium ([bmim]+) cation, while the phospholipid bilayer is made of 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine (POPC). Our investigations focus on structural and dynamical properties of phospholipid and water molecules that could be probed by inelastic and quasi-elastic neutron scattering measurements. The results confirm the fast incorporation of [bmim]+ into the lipid phase already observed in previous simulations, driven by the Coulomb attraction of the cation for the most electronegative oxygens in the POPC head group and by sizeable dispersion forces binding the neutral hydrocarbon tails of [bmim]+ and of POPC. The [bmim]+ absorption into the bilayer favours the penetration of water into POPC, causes a slight but systematic thinning of the bilayer, and further stabilises hydrogen bonds at the lipid/water interface that already in pure samples (no RTIL) display a lifetime much longer than in bulk water. On the other hand, the effect of RTILs on the diffusion constant of POPC (DPOPC) does not reveal a clearly identifiable trend, since DPOPC increases upon addition of [bmim][Cl] and decreases in the [bmim][PF6] case. Moreover, because of screening, the electrostatic signature of each bilayer is only moderately affected by the addition of RTIL ions in solution. The analysis of long wavelength fluctuations of the bilayers shows that RTIL sorption causes a general decrease of the lipid/water interfacial tension and bending rigidity, pointing to the destabilizing effect of RTILs on lipid bilayers.

Benedetto, Antonio; Bingham, Richard J.; Ballone, Pietro

2015-03-01

85

Structure and dynamics of POPC bilayers in water solutions of room temperature ionic liquids.  

PubMed

Molecular dynamics simulations in the NPT ensemble have been carried out to investigate the effect of two room temperature ionic liquids (RTILs), on stacks of phospholipid bilayers in water. We consider RTIL compounds consisting of chloride ([bmim][Cl]) and hexafluorophosphate ([bmim][PF6]) salts of the 1-buthyl-3-methylimidazolium ([bmim](+)) cation, while the phospholipid bilayer is made of 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine (POPC). Our investigations focus on structural and dynamical properties of phospholipid and water molecules that could be probed by inelastic and quasi-elastic neutron scattering measurements. The results confirm the fast incorporation of [bmim](+) into the lipid phase already observed in previous simulations, driven by the Coulomb attraction of the cation for the most electronegative oxygens in the POPC head group and by sizeable dispersion forces binding the neutral hydrocarbon tails of [bmim](+) and of POPC. The [bmim](+) absorption into the bilayer favours the penetration of water into POPC, causes a slight but systematic thinning of the bilayer, and further stabilises hydrogen bonds at the lipid/water interface that already in pure samples (no RTIL) display a lifetime much longer than in bulk water. On the other hand, the effect of RTILs on the diffusion constant of POPC (DPOPC) does not reveal a clearly identifiable trend, since DPOPC increases upon addition of [bmim][Cl] and decreases in the [bmim][PF6] case. Moreover, because of screening, the electrostatic signature of each bilayer is only moderately affected by the addition of RTIL ions in solution. The analysis of long wavelength fluctuations of the bilayers shows that RTIL sorption causes a general decrease of the lipid/water interfacial tension and bending rigidity, pointing to the destabilizing effect of RTILs on lipid bilayers. PMID:25833602

Benedetto, Antonio; Bingham, Richard J; Ballone, Pietro

2015-03-28

86

Room temperature ionic liquid as solvent for in situ Pd/H formation: hydrogenation of carbon-carbon double bonds.  

PubMed

This work undertakes mechanistic studies of H(+) reduction on a palladium microelectrode in a room temperature ionic liquid. It was found that the electrode was initially in a partially passivated state in [NTf(2)](-) based RTILs and that pre-anodisation of the electrode surface has a dramatic effect on the reversibility of the system, also triggering a change from hydrogen evolution to hydrogen absorption. Theoretical modelling supported the idea of Pd/H formation under these conditions. Utilising Pd/H as an activated hydrogen source, a proof-of-concept method for hydrogenation of multiple bond containing organic molecules by in situ generation of Pd/H via reduction of H(+) on palladium in a room temperature ionic liquid has been demonstrated. PMID:23223389

Martindale, Benjamin C M; Menshykau, Dzianis; Ernst, Sven; Compton, Richard G

2013-01-28

87

Electrolyte properties of 1-alkyl-2,3,5-trimethylpyrazolium cation-based room-temperature ionic liquids for lithium secondary batteries  

Microsoft Academic Search

The physicochemical and electrochemical properties of three 1-alkyl-2,3,5-trimethylpyrazolium cation-based room-temperature ionic liquids with various alkyl chain lengths were investigated. The temperature dependences of density, viscosity, and ionic conductivity were obtained by precise measurements. Electrolyte properties of these room-temperature ionic liquids were also examined from the viewpoint of their uses in lithium secondary batteries ([LiCoO2 positive electrode|electrolyte|lithium metal negative electrode]). It

Shiro Seki; Takeshi Kobayashi; Nobuyuki Serizawa; Yo Kobayashi; Katsuhito Takei; Hajime Miyashiro; Kikuko Hayamizu; Seiji Tsuzuki; Takushi Mitsugi; Yasuhiro Umebayashi; Masayoshi Watanabe

2010-01-01

88

Room-temperature ionic liquids and composite materials: platform technologies for CO(2) capture.  

PubMed

Clean energy production has become one of the most prominent global issues of the early 21st century, prompting social, economic, and scientific debates regarding energy usage, energy sources, and sustainable energy strategies. The reduction of greenhouse gas emissions, specifically carbon dioxide (CO(2)), figures prominently in the discussions on the future of global energy policy. Billions of tons of annual CO(2) emissions are the direct result of fossil fuel combustion to generate electricity. Producing clean energy from abundant sources such as coal will require a massive infrastructure and highly efficient capture technologies to curb CO(2) emissions. Current technologies for CO(2) removal from other gases, such as those used in natural gas sweetening, are also capable of capturing CO(2) from power plant emissions. Aqueous amine processes are found in the vast majority of natural gas sweetening operations in the United States. However, conventional aqueous amine processes are highly energy intensive; their implementation for postcombustion CO(2) capture from power plant emissions would drastically cut plant output and efficiency. Membranes, another technology used in natural gas sweetening, have been proposed as an alternative mechanism for CO(2) capture from flue gas. Although membranes offer a potentially less energy-intensive approach, their development and industrial implementation lags far behind that of amine processes. Thus, to minimize the impact of postcombustion CO(2) capture on the economics of energy production, advances are needed in both of these areas. In this Account, we review our recent research devoted to absorptive processes and membranes. Specifically, we have explored the use of room-temperature ionic liquids (RTILs) in absorptive and membrane technologies for CO(2) capture. RTILs present a highly versatile and tunable platform for the development of new processes and materials aimed at the capture of CO(2) from power plant flue gas and in natural gas sweetening. The desirable properties of RTIL solvents, such as negligible vapor pressures, thermal stability, and a large liquid range, make them interesting candidates as new materials in well-known CO(2) capture processes. Here, we focus on the use of RTILs (1) as absorbents, including in combination with amines, and (2) in the design of polymer membranes. RTIL amine solvents have many potential advantages over aqueous amines, and the versatile chemistry of imidazolium-based RTILs also allows for the generation of new types of CO(2)-selective polymer membranes. RTIL and RTIL-based composites can compete with, or improve upon, current technologies. Moreover, owing to our experience in this area, we are developing new imidazolium-based polymer architectures and thermotropic and lyotropic liquid crystals as highly tailorable materials based on and capable of interacting with RTILs. PMID:19795831

Bara, Jason E; Camper, Dean E; Gin, Douglas L; Noble, Richard D

2010-01-19

89

Metal-air cell comprising an electrolyte with a room temperature ionic liquid and hygroscopic additive  

DOEpatents

An electrochemical cell comprising an electrolyte comprising water and a hydrophobic ionic liquid comprising positive ions and negative ions. The electrochemical cell also includes an air electrode configured to absorb and reduce oxygen. A hydrophilic or hygroscopic additive modulates the hydrophobicity of the ionic liquid to maintain a concentration of the water in the electrolyte is between 0.001 mol % and 25 mol %.

Friesen, Cody A.; Krishnan, Ramkumar; Tang, Toni; Wolfe, Derek

2014-08-19

90

81929 - Fission-Product Separation Based on Room - Temperature Ionic Liquids  

SciTech Connect

This project has demonstrated that Sr2+ and Cs+ can be selectively extracted from aqueous solutions into ionic liquids using crown ethers and that unprecedented large distribution coefficients can be achieved for these fission products. The volume of secondary wastes can be significantly minimized with this new separation technology. Through the current EMSP funding, the solvent extraction technology based on ionic liquids has been shown to be viable and can potentially provide the most efficient separation of problematic fission products from high level wastes. The key results from the current funding period are the development of highly selective extraction process for cesium ions based on crown ethers and calixarenes, optimization of selectivities of extractants via systematic change of ionic liquids, and investigation of task-specific ionic liquids incorporating both complexant and solvent characteristics.

Robin D. Rogers

2004-12-09

91

Lithium-air batteries using hydrophobic room temperature ionic liquid electrolyte  

Microsoft Academic Search

Lithium-air batteries using hydrophobic ionic liquid consisting of 1-alkyl-3-methyl imidazolium cation and perfluoroalkylsulfonyl imide anion were investigated. 1-Ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)amide, which has high conductivity and prevents hydrolysis of the lithium anode, showed the best electrolyte performance. The cell worked for 56 days in air, and the cathode carbon materials showed high discharge capacity of 5360mAhg?1. In addition to hydrophobic ionic liquids

Takashi Kuboki; Tetsuo Okuyama; Takahisa Ohsaki; Norio Takami

2005-01-01

92

Dynamic Solvation in Room-Temperature Ionic Liquids P. K. Chowdhury, M. Halder, L. Sanders, T. Calhoun, J. L. Anderson, D. W. Armstrong,  

E-print Network

solvation of the fluorescent probe, coumarin 153, is measured in five room-temperature ionic liquids using of coumarin 153 are nearly superimposable at all temperatures in a given solvent unless they are obtained

Song, Xueyu

93

NOVEL FISSION PRODUCT SEPARATION BASED ON ROOM-TEMPERATURE IONIC LIQUIDS  

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.

2004-06-01

94

Determination of trace silver in environmental samples by room temperature ionic liquid-based preconcentration and flame atomic absorption spectrometry  

Microsoft Academic Search

We report on a new method for preconcentration of silver ion at trace level in environmental samples, and its subsequent determination\\u000a by flame atomic absorption spectrometry (FAAS). The room temperature ionic liquid (RTIL) 1-butyl-3-methylimidazolium hexafuorophosphate\\u000a and the chelator 5-(4-dimethylaminobenzylidene)-rhodanine were used for extraction. Ag(I) was back-extracted from the organic\\u000a phase into thiosulfate solution and then determined via FAAS. The effects

Chun-Gang Yuan; Ping Liang; Yang-Yang Zhang

95

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.

2005-11-13

96

Solvent extraction separation of Th-227 and Ac-225 in room temperature ionic liquids  

SciTech Connect

The solvent extractions of Th-227 and Ac-225 from the aqueous phase into ionic liquids (ILs) were investigated by using N,N,N ,N - tetraoctyldiglycolamide (TODGA) or di(2-ethylhexyl)phosphoric acid (HDEHP) as an extractant. Four ionic liquids, 1-butyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide ([C4mim][NTf2]), 1-butyl-3-methylimidazolium bis(perfluoroethanesulfonyl)imide ([C4mim][BETI]), 1-butyl-2,3-trimethyleneimidazolium (trifluoromethanesulfonyl)imide [BuI5][NTf2], and 1-benzyl pyridinium bis(trifluoromethanesulfonyl)imide ([PhCH2Py][NTf2]) were used as extraction solvents for separation of Th-227 and Ac-225 in this study. Excellent extraction efficiencies and selectivities were found for Th-227/Ac-225 when HDEHP was used as an extractant in these ionic liquids. The effects of different extractant concentrations in ionic liquids and acidities of the aqueous phase on extraction efficiencies and selectivities of Th-227/Ac-225 are also presented in this article.

Bell, Jason R [ORNL; Boll, Rose Ann [ORNL; Dai, Sheng [ORNL; Luo, Huimin [ORNL

2012-01-01

97

DETERMINATION OF HENRY'S LAW CONSTANTS FOR VOCS IN ROOM TEMPERATURE IONIC LIQUIDS  

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...

98

FISSION-PRODUCT SEPARATION BASED ON ROOM-TEMPERATURE IONIC LIQUIDS  

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...

99

Characterization of a novel intrinsic luminescent room-temperature ionic liquid based on [P6,6,6,14 ][ANS].  

PubMed

Intrinsically luminescent room-temperature ionic liquids (RTILs) can be prepared by combining a luminescent anion (more common) or cation with appropriate counter ions, rendering new luminescent soft materials. These RTILs are still new, and many of their photochemical properties are not well known. A novel intrinsic luminescent RTIL based on the 8-anilinonaphthalene-1-sulfonate ([ANS]) anion combined with the trihexyltetradecylphosphonium ([P6,6,6,14 ]) cation was prepared and characterized by spectroscopic techniques. Detailed photophysical studies highlight the influence of the ionic liquid environment on the ANS fluorescence, which together with rheological and (1) H?NMR experiments illustrate the effects of both the viscosity and electrostatic interactions between the ions. This material is liquid at room temperature and possesses a glass transition temperature (Tg ) of 230.4?K. The fluorescence is not highly sensitive to factors such as temperature, but owing to its high viscosity, dynamic Stokes shift measurements reveal very slow components for the IL relaxation. PMID:25124894

Delgado, Joana M; Raymundo, Anabela; Vilarigues, Márcia; Branco, Luís C; Laia, César A T

2015-01-01

100

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

101

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

PubMed

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

2007-03-01

102

Separation of N2O and CO2 using room-temperature ionic liquid [bmim][BF4].  

PubMed

We have developed a ternary equation of state (EOS) model for the N(2)O/CO(2)/1-butyl-3-methylimidazolium tetrafluoroborate ([bmim][BF(4)]) system in order to understand separation of these gases using room-temperature ionic liquids (RTILs). The present model is based on a generic RK (Redlich-Kwong) EOS, with empirical interaction parameters for each binary system. The interaction parameters have been determined using our measured VLE (vapor-liquid equilibrium) data for N(2)O/[bmim][BF(4)] and CO(2)/[bmim][BF(4)] and literature data for N(2)O/CO(2). The binary EOS models for the N(2)O/[bmim][BF(4)] and CO(2)/[bmim][BF(4)] systems correctly predicted the liquid-liquid phase separation found in VLLE experiments. The validity of the ternary EOS model has been checked by conducting VLE experiments for the N(2)O/CO(2)/[bmim][BF(4)] system over a range in temperature from 296 to 315 K. With this EOS model, solubility (VLE) behavior has been calculated for various (T, P, and feed compositions) conditions. For both large and small N(2)O/CO(2) feed ratios, the N(2)O/CO(2) gas selectivity [?(N(2)O/CO(2)) = (y(N(2)O)/x(N(2)O))/(y(CO(2))/x(CO(2)))] is ? = 1.4-1.5, compared with (? = 0.96-0.98) in the absence of ionic liquid. While the concentration of the ionic liquid does not affect the selectivity, the addition of an ionic liquid provides the only practical means of separating CO(2) and N(2)O. PMID:21405135

Shiflett, Mark B; Niehaus, Anne Marie S; Yokozeki, A

2011-04-01

103

Structure and dynamics of room temperature ionic liquids with bromide anion: results from (81) Br NMR spectroscopy.  

PubMed

We report the results of a comprehensive (81) Br NMR spectroscopic study of the structure and dynamics of two room temperature ionic liquids (RTILs), 1-butyl-3-methylimidazolium bromide ([C4 mim]Br) and 1-butyl-2,3-dimethylimidazolium bromide ([C4 C1 mim]Br), in both liquid and crystalline states. NMR parameters in the gas phase are also simulated for stable ion pairs using quantum chemical calculations. The combination of (81) Br spin-lattice and spin-spin relaxation measurements in the motionally narrowed region of the stable liquid state provides information on the correlation time of the translational motion of the cation. (81) Br quadrupolar coupling constants (CQ ) of the two RTILs were estimated to be 6.22 and 6.52?MHz in the crystalline state which were reduced by nearly 50% in the liquid state, although in the gas phase, the values are higher and span the range of 7-53?MHz depending on ion pair structure. The CQ can be correlated with the distance between the cation-anion pairs in all the three states. The (81) Br CQ values of the bromide anion in the liquid state indicate the presence of some structural order in these RTILs, the degree of which decreases with increasing temperature. On the other hand, the ionicity of these RTILs is estimated from the combined knowledge of the isotropic chemical shift and the appropriate mean energy of the excited state. [C4 C1 mim]Br has higher ionicity than [C4 mim]Br in the gas phase, while the situation is reverse for the liquid and the crystalline states. Copyright © 2015 John Wiley & Sons, Ltd. PMID:25783567

Endo, Takatsugu; Imanari, Mamoru; Hidaka, Yuki; Seki, Hiroko; Nishikawa, Keiko; Sen, Sabyasachi

2015-05-01

104

Differential scanning calorimetric study of nonionic surfactant mixtures with a room temperature ionic liquid, bmimBF4.  

PubMed

The melting behavior of polyethyleneglycol dodecyl ethers (C(12)E(6), C(12)E(7), and C(12)E(8)) in a room temperature ionic liquid, 1-butyl-3-methylimidazolium tetrafluoroborate (bmimBF(4)), was investigated by means of differential scanning calorimetry (DSC). The melting temperature as a function of the surfactant concentration, combined with the cmc curve and cloud point curve, provided phase diagrams for the surfactant/bmimBF(4) mixtures in solvent-rich region. The characteristic feature of the mixtures is an existence of the Krafft temperature which is usually not observed with aqueous solutions of nonionic surfactants. The heat of fusion as a function of the surfactant concentration provided the interaction energy between the surfactant and bmimBF(4). The interaction energy shows a linear dependence on the length of polyoxyethylene (POE) chain of the surfactants, which suggests that the solvation takes place around the POE chain. PMID:19501832

Inoue, Tohru; Higuchi, Yuka; Misono, Takeshi

2009-10-01

105

Biodiesel synthesis and conformation of lipase from Burkholderia cepacia in room temperature ionic liquids and organic solvents.  

PubMed

Biodiesel synthesis and conformation of Burkholderia cepacia lipase (BCL) were studied in 19 different room temperature ionic liquids (RTLLs) with a range of cation and anion structures. Overall, anion selection had a greater influence on biodiesel conversion than cation choice. RTILs containing Tf2N- and PF6- anions were suitable reaction media, while RTIL of [OmPy][BF4] was the best reaction medium with a biodiesel yield of 82.2±1.2%. RTILs with strong water miscible properties showed very low biodiesel yields. Conformational analysis by FT-IR revealed that higher biodiesel conversion in RTILs was correlated with a low tendency in ?-helix content of BCL. An ultrasound-assisted biocatalysis process in RTILs was used to improve mass transfer rate, leading to 83% reduction of the reaction time for biodiesel production. PMID:21955878

Liu, Yun; Chen, Dawei; Yan, Yunjun; Peng, Cheng; Xu, Li

2011-11-01

106

Electrochemistry of room temperature protic ionic liquids: a critical assessment for use as electrolytes in electrochemical applications.  

PubMed

Ten room temperature protic ionic liquids (RTPILs) have been prepared from low-molecular-weight Brønsted acids and amines with high purity and minimal water content, and their electrochemical characteristics determined using cyclic, microelectrode, and rotating disk electrode voltammetries. Potential windows of the 10 RTPILs were established at glassy carbon, gold, and platinum electrodes, where the largest potential window is generally observed with glassy carbon electrodes. The two IUPAC recommended internal potential reference systems, ferrocene/ferrocenium and cobaltocenium/cobaltocene, were determined for the 10 RTPILs, and their merits as well as limitations are discussed. Other electrochemical properties such as mass transport and double layer capacitances were also investigated. The potential applications of these RTPILs as electrolytes for electrochemical energy devices were discussed, and two novel applications using PILs for metal deposition and water electrolysis were demonstrated. PMID:22784243

Lu, Xunyu; Burrell, Geoff; Separovic, Frances; Zhao, Chuan

2012-08-01

107

Ion-exchange as a mode of cation transfer into room-temperature ionic liquids containing crown ethers : implications for the "greenness" of ionic liquids as diluents in liquid-liquid extraction.  

SciTech Connect

The transfer of strontium ion from acidic nitrate media into a series of 1-alkyl-3-methylimidazolium-based room-temperature ionic liquids containing dicyclohexano-18-crown-6 is shown to proceed via cation-exchange, in contrast to conventional solvents such as alkan-1-ols, in which extraction of a strontium nitrato-crown ether complex is observed.

Dietz, M.L.; Dzielawa, J.A.; Chemistry

2001-10-15

108

Highly Efficient Extraction of Phenolic Compounds by Use of Magnetic Room Temperature Ionic Liquids for Environmental Remediation  

PubMed Central

A hydrophobic magnetic room temperature ionic liquid (MRTIL), trihexyltetradecylphosphonium tetrachloroferrate(III) ([3C6PC14][FeCl4]), was synthesized from trihexyltetradecylphosphonium chloride and FeCl3·6H2O. This MRTIL was investigated as a possible separation agent for solvent extraction of phenolic compounds from aqueous solution. Due to its strong paramagnetism, [3C6PC14][FeCl4] 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 substitutents exhibited higher distribution ratios. For example, the distribution ratio of phenol (DPh) was 107. In contrast, 3,5-dichlorophenol distribution ratio (D3,5-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 [3C6PC14][FeCl4] 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 [3C6PC14][FeCl4] 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 [3C6PC14][FeCl4]. PMID:21783320

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

2011-01-01

109

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

PubMed

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

2011-09-15

110

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

Microsoft Academic Search

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

David Martin Ryan

2000-01-01

111

Dynamics of electrical double layer formation in room-temperature ionic liquids under constant-current charging conditions  

SciTech Connect

We report detailed simulation results on the formation dynamics of an electrical double layer (EDL) inside an electrochemical cell featuring room-temperature ionic liquids (RTILs) enclosed between two planar electrodes. Under relatively small charging currents, the evolution of cell potential during charging can be suitably predicted by the Landau-Ginzburg-type continuum model proposed recently (M. Z. Bazant, B. D. Storey, and A. A. Kornyshev, Phys. Rev. Lett., 106, 046102, 2011). Under very large charging currents, the cell potential shows pronounced oscillation during the initial stage of charging, a feature not captured by the continuum model. Such oscillation originates from the sequential growth of the ionic space charge layers near the electrode surface, allowing the evolution of EDLs in RTILs with time, an atomistic process difficult to visualize experimentally, to be studied by analyzing the cell potential under constant current charging conditions. While the continuum model cannot predict the potential oscillation under such far-from-equilibrium charging conditions, it can nevertheless qualitatively capture the growth of cell potential during the later stage of charging. Improving the continuum model by introducing frequency-dependent dielectric constant and density-dependent ion diffusion coefficients may help to further extend the applicability of the model. Keywords: ionic

Jiang, Xikai [ORNL] [ORNL; Huang, Jingsong [ORNL] [ORNL; Zhao, Hui [University of Nevada, Las Vegas] [University of Nevada, Las Vegas; Sumpter, Bobby G [ORNL] [ORNL; Qiao, Rui [Clemson University] [Clemson University

2014-01-01

112

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.  

PubMed

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

2012-10-30

113

Competitive complexation of nitrates and chlorides to uranyl in a room temperature ionic liquid.  

PubMed

By coupling EXAFS, UV-vis spectroscopy, and molecular dynamics and quantum mechanical calculations, we studied the competitive complexation of uranyl cations with nitrate and chloride ions in a water immiscible ionic liquid (IL), C(4)mimTf(2)N (C(4)mim(+): 1-butyl-3-methyl-imidazolium; Tf(2)N(-) = (CF(3)SO(2))(2)N)(-): bis(trifluoromethylsulfonyl)imide). Both nitrate and chloride are stronger ligands for uranyl than the IL Tf(2)N(-) or triflate anions and when those anions are simultaneously present, neither the limiting complex UO(2)(NO(3))(3)(-) nor UO(2)Cl(4)(2-) alone could be observed. At a U/NO(3)/Cl ratio of 1/2/2, the dominant species is likely UO(2)Cl(NO(3))(2)(-). When chloride is in excess over uranyl with different nitrate concentrations (U/NO(3)/Cl ratio of 1/2/6, 1/4/4, and 1/12/4) the solution contains a mixture of UO(2)Cl(4)(2-) and UO(2)Cl(3)(NO(3))(2-) species. Furthermore, it is shown that the experimental protocol for introducing these anions to the solution (either as uranyl counterion, as added salt, or as IL component) influences the UV-vis spectra, pointing to the formation of different kinetically equilibrated complexes in the IL. PMID:20557035

Gaillard, C; Chaumont, A; Billard, I; Hennig, C; Ouadi, A; Georg, S; Wipff, G

2010-07-19

114

Electrochemical gas sensors based on paper-supported room-temperature ionic liquids for improved analysis of acid vapours.  

PubMed

A prototype of a fast-response task-specific amperometric gas sensor based on paper-supported room-temperature ionic liquids (RTILs) is proposed here for improved analysis of volatile acid species. It consists of a small filter paper foil soaked with a RTIL mixture containing an ionic liquid whose anion (acetate) displays a basic character, upon which three electrodes are screen printed by carbon ink profiting from a suitable mask. It takes advantage of the high electrical conductivity and negligible vapour pressure of RTILs and of their easy immobilization into a porous and inexpensive supporting material such as paper. The performance of this device, used as a wall-jet amperometric detector for flow injection analyses of headspace samples in equilibrium with aqueous solutions at controlled concentrations, was evaluated for phenol and 1-butanethiol vapours which were adopted as model acid gaseous analytes. The results obtained showed that the quite high potentials required for the detection of these analytes are lowered significantly, thanks to the addition of the basic acetate RTIL. In such a way, overlap with the medium discharge is avoided, and the possible adverse effect of interfering species is minimised. The sensor performance was quite satisfactory (detection limits, ca. 0.3 ?M; dynamic range, ca. 1-200 ?M, both referred to solution concentrations; correlation coefficients in the range 0.993-0.997; repeatability, ± 6% RSD; long-term stability, 9%); thus suggesting the possible use of this device for manifold applications. PMID:23232956

Toniolo, Rosanna; Dossi, Nicolò; Pizzariello, Andrea; Casagrande, Alice; Bontempelli, Gino

2013-04-01

115

Room-temperature ionic liquid-amine solutions: tunable solvents for efficient and reversible capture of CO{sub 2}  

SciTech Connect

Solutions of room-temperature ionic liquids (RTILs) and commercially available amines were found to be effective for the capture of CO{sub 2} as carbamate salts. RTIL solutions containing 50 mol % (16% v/v) monoethanolamine (MEA) are capable of rapid and reversible capture of 1 mol of CO{sub 2} per 2 moles MEA to give an insoluble MEA-carbamate precipitate that helps to drive the capture reaction (as opposed to aqueous amine systems). Diethanolamine (DEA) can also be used in the same manner for CO{sub 2} capture in RTILs containing a pendant hydroxyl group. The captured CO{sub 2} in the resulting RTIL-carbamate salt mixtures can be readily released by either heating and/or subjecting them to reduced pressure. Using this unprecedented and industrially attractive mixing approach, the desirable properties of RTILs (i.e., nonvolatility, enhancedCO{sub 2} solubility, lower heat capacities) can be combined with the performance of amines for CO{sub 2} capture without the use of specially designed, functionalized 'task-specific' ionic liquids. By mixing RTILs with commercial amines, reactive solvents with a wide range of amine loading levels can be tailored to capture CO{sub 2} in a variety of conditions and processes. These RTIL-amine solutions behave similarly to their water-based counterparts but may offer many advantages, including increased energy efficiency, compared to current aqueous amine technologies.

Dean Camper; Jason E. Bara; Douglas L. Gin; Richard D. Noble [University of Colorado, Boulder, CO (United States). Department of Chemical and Biological Engineering

2008-11-05

116

Facile pretreatment of lignocellulosic biomass at high loadings in room temperature ionic liquids.  

PubMed

Ionic liquids (ILs) have emerged as attractive solvents for lignocellulosic biomass pretreatment in the production of biofuels and chemical feedstocks. However, the high cost of ILs is a key deterrent to their practical application. Here, we show that acetate based ILs are effective in dramatically reducing the recalcitrance of corn stover toward enzymatic polysaccharide hydrolysis even at loadings of biomass as high as 50% by weight. Under these conditions, the IL serves more as a pretreatment additive rather than a true solvent. Pretreatment of corn stover with 1-ethyl-3-methylimidizolium acetate ([Emim] [OAc]) at 125 ± 5°C for 1 h resulted in a dramatic reduction of cellulose crystallinity (up to 52%) and extraction of lignin (up to 44%). Enzymatic hydrolysis of the IL-treated biomass was performed with a common commercial cellulase/xylanase from Trichoderma reesei and a commercial ?-glucosidase, and resulted in fermentable sugar yields of ?80% for glucose and ?50% for xylose at corn stover loadings up to 33% (w/w) and 55% and 34% for glucose and xylose, respectively, at 50% (w/w) biomass loading. Similar results were observed for the IL-facilitated pretreatment of switchgrass, poplar, and the highly recalcitrant hardwood, maple. At 4.8% (w/w) corn stover, [Emim][OAc] can be readily reused up to 10 times without removal of extracted components, such as lignin, with no effect on subsequent fermentable sugar yields. A significant reduction in the amount of IL combined with facile recycling has the potential to enable ILs to be used in large-scale biomass pretreatment. PMID:21769858

Wu, Hong; Mora-Pale, Mauricio; Miao, Jianjun; Doherty, Thomas V; Linhardt, Robert J; Dordick, Jonathan S

2011-12-01

117

Dynamics of electrical double layer formation in room-temperature ionic liquids under constant-current charging conditions  

NASA Astrophysics Data System (ADS)

We report detailed simulation results on the formation dynamics of an electrical double layer (EDL) inside an electrochemical cell featuring room-temperature ionic liquids (RTILs) enclosed between two planar electrodes. Under relatively small charging currents, the evolution of cell potential from molecular dynamics (MD) simulations during charging can be suitably predicted by the Landau-Ginzburg-type continuum model proposed recently (Bazant et al 2011 Phys. Rev. Lett. 106 046102). Under very large charging currents, the cell potential from MD simulations shows pronounced oscillation during the initial stage of charging, a feature not captured by the continuum model. Such oscillation originates from the sequential growth of the ionic space charge layers near the electrode surface. This allows the evolution of EDLs in RTILs with time, an atomistic process difficult to visualize experimentally, to be studied by analyzing the cell potential under constant-current charging conditions. While the continuum model cannot predict the potential oscillation under such far-from-equilibrium charging conditions, it can nevertheless qualitatively capture the growth of cell potential during the later stage of charging. Improving the continuum model by introducing frequency-dependent dielectric constant and density-dependent ion diffusion coefficients may help to further extend the applicability of the model. The evolution of ion density profiles is also compared between the MD and the continuum model, showing good agreement.

Jiang, Xikai; Huang, Jingsong; Zhao, Hui; Sumpter, Bobby G.; Qiao, Rui

2014-07-01

118

Characterization of uranyl(VI) nitrate complexes in a room temperature ionic liquid using attenuated total reflection-Fourier transform infrared spectrometry.  

PubMed

Room temperature ionic liquids form potentially important solvents in novel nuclear waste reprocessing methods, and the solvation, speciation, and complexation behaviors of actinides and lanthanides in room temperature ionic liquids is of current interest. In this study, the coordination environment of uranyl(VI) in solutions of the room temperature ionic liquid 1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide containing either tetrabutylammonium nitrate or nitric acid was characterized using attenuated total reflection-Fourier transform infrared spectrometry. Both UO(2)(NO(3))(2) and UO(2)(NO(3))(3)(-) species were detected in solutions containing tetrabutylammonium nitrate. ?(as)(UO(2)) for these two species were found to lie at 951 and 944 cm(-1), respectively, while ?(as)(UO(2)) arising from uranyl(VI) coordinated by bis(trifluoromethylsulfonyl)imide anions in 1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide was found to lie at 968 cm(-1). In solutions containing nitric acid, only UO(2)(NO(3))(2) was detected, due to the high water content. The UO(2)(NO(3))(+) species was not detected under the conditions used in this study. From the results shown here, we conclude that infrared spectroscopy forms a valuable addition to the suite of tools currently used to study the chemical behavior of uranyl(VI) in room temperature ionic liquids. PMID:20722398

Quach, Donna L; Wai, Chien M; Pasilis, Sofie P

2010-09-20

119

A task-specific ionic liquid [bmim]SCN for the conversion of alkyl halides to alkyl thiocyanates at room temperature  

Microsoft Academic Search

A new “task-specific” ionic liquid (TSIL), 1-n-butyl-3-methylimidazolium thiocyanate ([bmim]SCN), has been prepared and used for the first time as the medium as well as reactant for the synthesis of alkyl thiocyanates from the corresponding alkyl halides by thiocyanate-halide exchange at room temperature. The alkyl thiocyanate products can be easily isolated from the reaction mixture by simple extraction and the ionic

Ahmed Kamal; Gagan Chouhan

2005-01-01

120

Room temperature ionic liquid 1-ethyl-3-hexylimidazolium-bis(trifluoromethylsulfonyl)-imide as lubricant for steel–steel contact  

Microsoft Academic Search

The ionic liquid 1-ethyl-3-hexylimidazolium-bis(trifluoromethylsulfonyl)-imide was synthesized and evaluated as lubricant for the contact of steel\\/steel. The tribological properties of the ionic liquid as lubricant were investigated on an Optimol SRV oscillating friction and wear tester in ambient condition. The synthetic ionic liquid shows excellent tribological performance and is superior to the ionic liquid of alkylimidazolium tetrafluoroborate and the conventional high

Qiming Lu; Haizhong Wang; Chengfeng Ye; Weimin Liu; Qunji Xue

2004-01-01

121

Optical properties of irradiated imidazolium based room temperature ionic liquids: new microscopic insights into the radiation induced mutations.  

PubMed

Considering the future perspectives of room temperature ionic liquids (RTILs) in areas involving high radiation fields (such as the nuclear fuel cycle and space applications), it is essential to probe and have a microscopic understanding of the radiation induced perturbations in the molecular structures and the intrinsic bonding interactions existing in the ILs. Herein, a focused investigation concerning the photophysical behavior of post-irradiated FAP (fluoroalkyl phosphate) imidazolium ILs revealed considerable rearrangements and bonding realignments of the ionic moieties in the ILs on irradiation, however, their physicochemical properties do not change significantly even at high absorbed doses. Most interestingly, the well-established excitation wavelength dependent fluorescence (FL) behavior of the ILs was considerably perturbed on irradiation and this is attributed to the radiation induced decoupling of pre-existing different associated structures of ions, and the subsequent formation of oligomers and other species containing multiple bond order groups. This was further substantiated by vibrational studies, where peaks appearing in the range 1600-1800 cm(-1) indicated the formation of double bonded products. Furthermore, for the hydroxyl functionalized (in the alkyl side chain of the imidazolium cation) IL, a blue shift in the O-H stretching frequency was observed for the -OH group H-bonded to the FAP anion (?OH[FAP](-)), while a red shift was observed for the H-bonded -OH groups in the cationic clusters. The FL lifetime values were found to increase with irradiation, which clearly indicates the enhancement in the rigidity level in the vicinity of the ions, thereby hindering the non-radiative decay processes. Such studies could contribute to the fundamental understanding of the radiation driven perturbations in the structure-property relationships, which eventually affect the radiolytic degradation pathways and the product distribution in RTILs. PMID:25824481

Guleria, Apurav; Singh, Ajay K; Adhikari, Soumyakanti

2015-04-01

122

Ultraslow dynamics at crystallization of a room-temperature ionic liquid, 1-butyl-3-methylimidazolium bromide.  

PubMed

We studied the crystallization process of 1-butyl-3-methylimidazolium bromide ([C(4)mim]Br) using measurements of supersensitive scanning calorimetry, free induction decay (FID) signals of (1)H NMR, and direct observation. These three methods provided consistent, complementary results, which showed extremely slow dynamics at crystallization. This sample does not crystallize during the cooling process, loses mobility, and changes to a coagulated state, which is not the thermodynamic glass state. The FID signals and direct observation in the heating process indicate that the coagulated sample liquefies just before crystallization. The crystallization of [C(4)mim]Br does not occur from specialized locations such as the surface or wall of the sample tube but randomly in the liquid. The calorimetric measurements show that it takes 150 min for approximately 3 mg of this sample to crystallize perfectly. Conformational changes of the butyl group continue for approximately 330 min after crystallization. Such slow dynamics are thought to be due to the cooperative linking of crystallization and complex conformational changes in dense fields with high viscosity. PMID:22409655

Imanari, Mamoru; Fujii, Kozo; Endo, Takatsugu; Seki, Hiroko; Tozaki, Ken-ichi; Nishikawa, Keiko

2012-04-01

123

The joint effects of room temperature ionic liquids and ordered media on fluorescence characteristics of estrogens in water and methanol  

NASA Astrophysics Data System (ADS)

This study investigated the steady-state and time-resolved fluorescence properties of 17?-ethinylestradiol (EE2) and 17?-estradiol (E2) in the presence of ordered media (?-cyclodextrins (?-CD) and cetyltrimethylammonium bromide (CTAB)). In addition, we analyzed the effects of four room temperature ionic liquids (RTILs) on the fluorescence intensities (FIs) of EE2/?-CD and E2/?-CD inclusion complexes in methanol. Both ?-CD and CTAB enhanced the fluorescence of EE2 and E2. The FIs of EE2 and E2 with ?-CD or CTAB in methanol were greater than those in water, possibly resulting from decreased oxygen-quenching in H2O molecules. ?-CD and CTAB may form inclusion complexes with estrogen in both water and methanol. The inclusion ratio of the complex was 1:1 and the inclusion constant (K) values in water were greater than those in methanol. The fluorescence lifetimes were 2.50 and 4.13 ns for EE2 and 2.58 and 4.03 ns for E2 in aqueous solution and methanol, respectively. The changing trend of fluorescence lifetimes for EE2 and E2 in ?-CD or CTAB was similar to the steady-state FIs. The four RTILs had a significant quenching effect on the FIs of EE2/?-CD and E2/?-CD, and the quenching process for EE2/?-CD and E2/?-CD by RTILs was demonstrated to be a dynamic quenching mechanism. Fluorescent data obtained from these complex systems provide a theoretical foundation for understanding the interaction mechanisms between ordered media and RTILs in the analysis of estrogens.

Wang, Huili; Duan, Ailian; Dahlgren, Randy A.; Li, Yanyan; Li, Changli; Wang, Wenwei; Zeng, Aibing; Wang, Xuedong

2014-07-01

124

Direct electrochemistry and electrocatalysis of hemoglobin immobilized into poly (lactic- co-glycolic acid)\\/room temperature ionic liquid composite film  

Microsoft Academic Search

A promising material of poly(lactic-co-glycolic acid) (PLGA) and, room temperature ionic liquid (ILs) (1-butyl-3-methylimidazolium tetrafluoroborate ([BMIM]BF4) was firstly used as an immobilization matrix to entrap proteins and its bioelectrochemical properties were studied. Direct electrochemistry and electrocatalytic behaviors of hemoglobin (Hb) entrapped in the PLGA\\/ILs composite film on the surface of glass carbon electrode were investigated. UV–vis spectroscopy, cyclic voltammetry (CV)

Yao Zhang; Xiumei Sun; Nengqin Jia

2011-01-01

125

Effect of nitrate, perchlorate, and water on uranyl(VI) speciation in a room-temperature ionic liquid: a spectroscopic investigation.  

PubMed

Room-temperature ionic liquids form potentially important solvents in novel nuclear waste reprocessing methods, and the solvation, speciation, and complexation behaviors of lanthanides and actinides in these solvents are of great current interest. In the study reported here, the coordination environment of uranyl(VI) in solutions of the room-temperature ionic liquid 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ([EMIM][Tf(2)N]) containing perchlorate, tetrabutylammonium nitrate, and water was investigated using Raman, ATR-FTIR, and NMR spectroscopies in order to better understand the role played in uranyl(VI) solution chemistry in room-temperature ionic liquids by water and other small, weakly complexing ligands. The (2)H NMR chemical shift for water in a solution of uranyl perchlorate hexahydrate in [EMIM][Tf(2)N] appears at 6.52 ppm, indicating that water is coordinated to uranyl(VI). A broad ?(OH) stretching mode at 3370 cm(-1) in the ATR-FTIR spectrum shows that this coordinated water is engaged in hydrogen bonding with water molecules in a second coordination sphere. A significant upfield shift in the (2)H NMR signal for water and the appearance of distinct ?(as)(HOH) (at 3630 cm(-1)) and ?(s)(HOH) (at 3560 cm(-1)) vibrational bands in the ATR-FTIR spectra show that coordinated water is displaced by nitrate upon formation of the UO(2)(NO(3))(2) and UO(2)(NO(3))(3)(-) complexes. The Raman spectra indicate that perchlorate complexed to uranyl(VI) is also displaced by nitrate. Our results indicate that perchlorate and water, though weakly complexing ligands, do have a role in uranyl(VI) speciation in room-temperature ionic liquids and that Raman, infrared, and NMR spectroscopies are valuable additions to the suite of tools currently used to study the chemical behavior of uranyl(VI)-ligand complexes in these solvents. PMID:21786806

Pasilis, Sofie P; Blumenfeld, Alexander

2011-09-01

126

High Power Electric Double-Layer Capacitors based on Room-Temperature Ionic Liquids and Nanostructured Carbons  

NASA Astrophysics Data System (ADS)

The efficient storage of electrical energy constitutes both a fundamental challenge for 21st century science and an urgent requirement for the sustainability of our technological civilization. The push for cleaner renewable forms of energy production, such as solar and wind power, strongly depends on a concomitant development of suitable storage methods to pair with these intermittent sources, as well as for mobile applications, such as vehicles and personal electronics. In this regard, Electrochemical Double-Layer Capacitors (supercapacitors) represent a vibrant area of research due to their environmental friendliness, long lifetimes, high power capability, and relative underdevelopment when compared to electrochemical batteries. Currently supercapacitors have gravimetric energies one order of magnitude lower than similarly advanced batteries, while conversly enjoying a similar advantage over them in terms of power. The challenge is to increase the gravimentric energies and conserve the high power. On the material side, research focuses on highly porous supports and electrolytes, the critical components of supercapacitors. Through the use of electrolyte systems with a wider electrochemical stability window, as well as properly tailored carbon nanomaterials as electrodes, significant improvements in performance are possible. Room Temperature Ionic Liquids and Carbide-Derived Carbons are promising electrolytes and electrodes, respectively. RTILs have been shown to be stable at up to twice the voltage of organic solvent-salt systems currently employed in supercapacitors, and CDCs are tunable in pore structure, show good electrical conductivity, and superior demonstrated capability as electrode material. This work aims to better understand the interplay of electrode and electrolyte parameters, such as pore structure and ion size, in the ultimate performance of RTIL-based supercapacitors in terms of power, energy, and temperature of operation. For this purpose, carbon nanomaterials such as nanoporous CDC nanopowders, vertically aligned carbon nanotube arrays, and single wall carbon nanotube aerogels, were synthesized and used as electrodes, alongside RTIL electrolytes with systematically varying ion sizes and compositions. While electrode/electrolyte development can take place along parallel lines, both must be properly matched to the device's ultimate operating conditions and specific application. The resulting devices exhibit good performance characteristics, and the best temperature range of any electrochemical storage device to date.

Perez, Carlos R.

127

Lithium secondary batteries using an asymmetric sulfonium-based room temperature ionic liquid as a potential electrolyte  

Microsoft Academic Search

A new asymmetric sulfonium-based ionic liquid, 1-butyldimethylsulfonium bis(trifluoromethylsulfonyl) imide (S114TFSI), was developed as electrolyte material for lithium secondary battery. Its cathodic potential was a little more positive\\u000a against the Li\\/Li+, so vinylene carbonate (VC) was added into the LiTFSI\\/S114TFSI ionic liquid electrolyte to ensure the formation of a solid electrolyte interface (SEI), which effectively prevented\\u000a the decomposition of the electrolyte.

ShiChun Luo; ZhengXi Zhang; Li Yang

2008-01-01

128

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

129

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

2006-01-01

130

Using room temperature ionic liquid to fabricate PEDOT\\/TiO 2 nanocomposite electrode-based electrochromic devices with enhanced long-term stability  

Microsoft Academic Search

In this work, poly(3,4-ethylenedioxythiophene)(PEDOT) was electrochemically incorporated with nano- and mesoporous TiO2 films to form PEDOT\\/TiO2 nanocomposite electrochromic electrodes. TiO2 films were introduced to enhance the interfacial adhesion of the polymers to the substrates and thus increase the long-term stability of electrodes of electrochromic devices (ECDs). Room temperature ionic liquid (RTIL)- 1-butyl-3-methyl-imidazolium tetrafluoroborate ([BMIM]BF4) was employed to serve as electrolyte

LongJian Ma; YongXiang Li; XiaoFeng Yu; QunBao Yang; Chang-Ho Noh

2008-01-01

131

Green and moisture-stable Lewis acidic ionic liquids (choline chloride · xZnCl 2) catalyzed protection of carbonyls at room temperature under solvent-free conditions  

Microsoft Academic Search

Choline chloride·xZnCl2 (x=1–3) or benzyltrimethylammonium chloride·2ZnCl2 have been used as efficient and recyclable catalysts for protection of carbonyls to 1,3-dioxolanes and 1,3-dioxanes at room temperature under solvent-free conditions. FT-IR investigation demonstrates the four ionic liquids have similar Lewis acid strength, which is in agreement with the activities observed in the acetalization reaction. The catalytic system choline chloride·2ZnCl2 can be reused

Zhiying Duan; Yanlong Gu; Youquan Deng

2006-01-01

132

One electron oxygen reduction in room temperature ionic liquids: A comparative study of Butler-Volmer and Symmetric Marcus-Hush theories using microdisc electrodes  

E-print Network

The voltammetry for the reduction of oxygen at a microdisc electrode is reported in two room temperature ionic liquids: 1-butyl-1-methylpyyrolidinium bis(trifluoromethylsulfonyl) imide ([Bmpyrr][NTf2]) and trihexyltetradecylphosphonium bis9trifluoromethylsulfonyl) imide ([P14,6,6,6][NTf2]) at 298 K. Simulated voltammograms using Butler-Volmer theory and Symmetric Marcus-Hush (SMH) theory were compared with experimental data. Butler-Volmer theory consistently provided experimental parameters with a higher level of certainty than SMH theory. A value of solvent reorganisation energy for oxygen reduction in ionic liquids was inferred for the first time as 0.4-0.5 eV, which is attributable to inner-sphere reorganisation with a negligible contribution from solvent reorganisation. The developed Butler-Volmer and Symmetric Marcus-Hush programs are also used to theoretically study the possibility of kinetically limited steady state currents, and to establish an approximate equivalence relationship between microdisc el...

Tanner, Eden E L; Barnes, Edward O; Compton, Richard G

2015-01-01

133

Production of CNT-taxol-embedded PCL microspheres using an ammonium-based room temperature ionic liquid: as a sustained drug delivery system.  

PubMed

We describe a one-pot method for the mass production of polymeric microspheres containing water-soluble carbon-nanotube (w-CNT)-taxol complexes using an ammonium-based room temperature ionic liquid. Polycaprolactone (PCL), trioctylmethylammonium chloride (TOMAC; liquid state from -20 to 240°C), and taxol were used, respectively, as a model polymer, room temperature ionic liquid, and drug. Large quantities of white colored PCL powder without w-CNT-taxol complexes and gray colored PCL powders containing w-CNT-taxol (1:1 or 1:2 wt/wt) complexes were produced by phase separation between the hydrophilic TOMAC and the hydrophobic PCL. Both microsphere types had a uniform, spherical structure of average diameter 3-5?m. The amount of taxol embedded in PCL microspheres was determined by HPLC and (1)H NMR to be 8-12?g per 1.0mg of PCL (loading capacity (LC): 0.8-1.2%; entrapment efficiency (EE): 16-24%). An in vitro HPLC release assay showed sustain release of taxol without an initial burst over 60days at an average rate of 0.003-0.0073mg per day. The viability patterns of human breast cancer cells (MCF-7) for PCTx-1 and -2 showed dose-dependent inhibitory effects. In the presence of PCTx-1 and -2, the MCF-7 cells showed high viability in the concentration level of, respectably, <70 and <5?g/mL. PMID:25527087

Kim, Seong Yeol; Hwang, Ji-Young; Seo, Jae-Won; Shin, Ueon Sang

2015-03-15

134

Self-assembly of imidazolium-based surfactants in magnetic room-temperature ionic liquids: binary mixtures.  

PubMed

The phase behaviour of binary mixtures of ionic surfactants (1-alkyl-3-imidazolium chloride, C(n)mimCl with n=14, 16 and 18) and imidazolium-based ionic liquids (1-alkyl-3-methylimidazolium tetrachloroferrate, C(n)mimFeCl4, with n=2 and 4) over a broad temperature range and the complete range of compositions is described. By using many complementary methods including differential scanning calorimetry (DSC), polarised microscopy, small-angle neutron and X-ray scattering (SANS/SAXS), and surface tension, the ability of this model system to support self-assembly is described quantitatively and this behaviour is compared with common water systems. The existence of micelles swollen by the solvent can be deduced from SANS experiments and represent a possible model for aggregates, which has barely been considered for ionic-liquid systems until now, and can be ascribed to the rather low solvophobicity of the surfactants. Our investigation shows that, in general, C(n)mimCl is a rather weak amphiphile in these ionic liquids. The amphiphilic strength increases systematically with the length of the alkyl chain, as seen from the phase behaviour, the critical micelle concentration, and also the level of definition of the aggregates formed. PMID:25314359

Klee, Andreas; Prevost, Sylvain; Gradzielski, Michael

2014-12-15

135

Ionic liquid-based single drop microextraction and room-temperature gas chromatography for on-site ion mobility spectrometric analysis.  

PubMed

The combination of ionic liquid-based headspace single drop microextraction (IL-HS-SDME) and room-temperature gas chromatography/ion mobility spectrometry (RTGC-IMS) is presented for the first time using the direct determination of trihalomethanes in waters as model analytical problem. The ionic liquid allows the transference of the analytes from the sample to the analytical system, at the same time that it provides an increase of the sensitivity and selectivity of the determination. An injection unit has been designed to permit the efficient volatilization of the analytes at room temperature and to avoid the entering of IL in the system. The direct combination allows the determination of the halocompounds in a rapid and simple way taking advance of their characteristic IMS spectra. The limits of the detection range between 0.1 ng mL(-1) (bromoform) and 0.9 ng mL(-1) (chloroform), the reproducibility of the system being better than 7.1% (RSD). The proposed coupling opens up a new horizon in IMS-based applications. PMID:19523638

Aguilera-Herrador, Eva; Lucena, Rafael; Cárdenas, Soledad; Valcárcel, Miguel

2009-07-17

136

Room temperature ionic liquid with silver salt as efficient reaction media for propylene\\/propane separation: Absorption equilibrium  

Microsoft Academic Search

In this study the selective absorption of propylene from their mixtures with propane by chemical complexation with silver ions in ionic liquid solutions has been performed.The solubilities of propylene and propane in the reactive medium, silver tetrafluoroborate dissolved in 1-butyl-3-methylimidazolium tetrafluoroborate (silver salt concentration=0.25M), were investigated as functions of temperature and pressure. The temperature range was between 278 and 318K

Alfredo Ortiz; Alicia Ruiz; Daniel Gorri; Inmaculada Ortiz

2008-01-01

137

1/f spectrum and memory function analysis of solvation dynamics in a room-temperature ionic liquid  

E-print Network

To understand the non-exponential relaxation associated with solvation dynamics in the ionic liquid 1-ethyl-3-methylimidazolium hexafluorophosphate, we study power spectra of the fluctuating Franck-Condon energy gap of a diatomic probe solute via molecular dynamics simulations. Results show 1/f dependence in a wide frequency range over 2 to 3 decades, indicating distributed relaxation times. We analyze the memory function and solvation time in the framework of the generalized Langevin equation using a simple model description for the power spectrum. It is found that the crossover frequency toward the white noise plateau is directly related to the time scale for the memory function and thus the solvation time. Specifically, the low crossover frequency observed in the ionic liquid leads to a slowly-decaying tail in its memory function and long solvation time. By contrast, acetonitrile characterized by a high crossover frequency and (near) absence of 1/f behavior in its power spectra shows fast relaxation of the memory function and single-exponential decay of solvation dynamics in the long-time regime.

Daun Jeong; M. Y. Choi; YounJoon Jung; Hyung J. Kim

2008-03-31

138

Protein Crystallization Using Room Temperature Ionic Fluids  

NASA Technical Reports Server (NTRS)

The ionic liquids (ILs) 1-butyl-3-methylimidizolium chloride (C4mim-C1), 1-butyl-3- methylimidizolium diethyleneglycol monomethylethersulfate ([C4mim]DEMGS), and 1-butyl-1 -methylpyrollidinium dihydrogenphosphate ([p1,4]dhp) were tested for their effects on the crystallization of the proteins canavalin, beta-lactoglobulin B, xylanase, and glucose isomerase, using a standard high throughput screen. The crystallization experiments were set up with the ILs added to the protein solutions at 0.2 and 0.4 M final concentrations. Crystallization droplets were set up at three proteixprecipitant ratios (1:1, 2:1, and 4:l), which served to progressively dilute the effects of the screen components while increasing the equilibrium protein and IL concentrations. Crystals were obtained for all four proteins at a number of conditions where they were not obtained from the IL-free control experiment. Over half of the protein-IL combinations tested had more successful outcomes than negative, where the IL-free crystallization was better than the corresponding IL-containing outcome, relative to the control. One of the most common causes of a negative outcome was solubilization of the protein by the IL, resulting in a clear drop. In one instance, we were able to use the IL-induced solubilizing to obtain beta-lactoglobulin B crystals from conditions that gave precipitated protein in the absence of IL. The results suggest that it may be feasible to develop ILs specifically for the task of macromolecule crystallization.

Pusey, Marc L.; Paley, Mark Steve; Turner, Megan B.; Rogers, Robin D.

2006-01-01

139

Solvation of uranyl(II), europium(III) and europium(II) cations in "basic" room-temperature ionic liquids: a theoretical study.  

PubMed

We report a molecular dynamics study of the solvation of UO2(2+), Eu3+ and Eu2+ ions in two "basic" (Lewis acidity) room-temperature ionic liquids (IL) composed of the 1-ethyl-3-methylimidazolium cation (EMI+) and a mixture of AlCl4- and Cl- anions, in which the Cl-/AlCl4- ratio is about 1 and 3, respectively. The study reveals the importance of the [UO2Cl4]2- species, which spontaneously form during most simulations, and that the first solvation shell of europium is filled with Cl- and AlCl4- ions embedded in a cationic EMI+ shell. The stability of the [UO2Cl4]2- and [Eu(III)Cl6]3- complexes is supported by quantum mechanical calculations, according to which the uranyl and europium cations intrinsically prefer Cl- to the AlCl4- ion. In the gas phase, however, [Eu(III)Cl6]3- and [Eu(II)Cl6]4- complexes are predicted to be metastable and to lose two to three Cl- ions. This contrasts with the results of simulations of complexes in ILs, in which the "solvation" of the europium complexes increases with the number of coordinated chlorides, leading to an equilibrium between different chloro species. The behavior of the hydrated [Eu(OH2)8]3+ complex is considered in the basic liquids; the complex exchanges H2O molecules with Cl- ions to form mixed [EuCl3(OH2)4] and [EuCl4(OH2)3]- complexes. The results of the simulations allow us to better understand the microscopic nature and solvation of lanthanide and actinide complexes in "basic" ionic liquids. PMID:15317055

Chaumont, Alain; Wipff, Georges

2004-08-20

140

Part I. Synthesis and characterization of C2 substituted imidazolium room temperature ionic liquids. Part II. Survey and analysis of organic chemistry textbooks  

NASA Astrophysics Data System (ADS)

Part I. Among room temperature ionic liquids (RTILs), those derived from the imidazolium cation are the most common. RTILs have generally been viewed solely as solvents, but they are able to participate in certain types of reactions, particularly due to the relatively high acidity at the imidazolium C2. Deprotonation affords N-heterocyclic carbenes (NHCs), which can cause unwanted side reactions. Consequently, the major limitation of imidazolium RTILs is that they cannot be used as solvents in highly basic reactions such as the Baylis-Hillman and Grignard reactions. This work reveals a convenient route for the preparation of C2-substituted imidazolium ionic liquids. This method involves the alkylation of N-heterocyclic carbenes, which are readily generated from the C2-unsubstituted imidazolium ionic liquids. It works well for nonfunctionalized alkyl chlorides and less well for alkyl bromides and iodides, likely due to competing elimination reactions. The resulting C2-substituted salts can be transformed into ionic liquids via standard anion metathesis reactions. Part II. Recent advances in media and the increasingly encyclopedic nature of traditional textbooks have made their role in college classes uncertain. In an effort to discover what is really being taught in organic chemistry courses across the US, a survey of organic chemistry professors in all 50 states was conducted to determine what material is covered in their organic chemistry courses for science majors. Survey Monkey, an online survey program, was used to construct a short 10-item survey which was sent to organic chemistry professors at various types of institutions across the nation. We sent out 2417 surveys and received 489 responses. The results of this survey revealed what topics the professors believe is core material and what they feel is extraneous. Additionally, this research identifies the things these professors would like to see changed in the organic chemistry texts. From the open-ended portion of the survey data, an analysis of organic chemistry textbooks was created. Books were analyzed for number and types of problems, number of example problems, and number of problems containing answers in the back of the book. The analysis of the thirteen books revealed there was a statistically significant difference between the books in number and types of problems. This work will reveal the findings of the analysis.

Ennis, Elliot G.

141

Electrochemistry and spectroelectrochemistry of 1,4-dinitrobenzene in acetonitrile and room-temperature ionic liquids: ion-pairing effects in mixed solvents.  

PubMed

Room-temperature ionic liquids (RTILs) have been shown to have a significant effect on the redox potentials of compounds such as 1,4-dinitrobenzene (DNB), which can be reduced in two one-electron steps. The most noticeable effect is that the two one-electron waves in acetonitrile collapsed to a single two-electron wave in a RTIL such as butylmethyl imidazolium-BF4 (BMImBF4). In order to probe this effect over a wider range of mixed-molecular-solvent/RTIL solutions, the reduction process was studied using UV-vis spectroelectrochemistry. With the use of spectroelectrochemistry, it was possible to calculate readily the difference in E°'s between the first and second electron transfer (?E12° = E1° - E2°) even when the two one-electron waves collapsed into a single two-electron wave. The spectra of the radical anion and dianion in BMImPF6 were obtained using evolving factor analysis (EFA). Using these spectra, the concentrations of DNB, DNB(-•), and DNB(2-) were calculated, and from these concentrations, the ?E12° values were calculated. Significant differences were observed when the bis(trifluoromethylsulfonyl)imide (NTf2) anion replaced the PF6(-) anion, leading to an irreversible reduction of DNB in BMImNTf2. The results were consistent with the protonation of DNB(2-), most likely by an ion pair between DNB(2-) and BMIm(+), which has been proposed by Minami and Fry. The differences in reactivity between the PF6(-) and NTf2(-) ionic liquids were interpreted in terms of the tight versus loose ion pairing in RTILs. The results indicated that nanostructural domains of RTILs were present in a mixed-solvent system. PMID:24884098

Atifi, Abderrahman; Ryan, Michael D

2014-07-01

142

Electrochemical detection of arsenic(III) completely free from noble metal: Fe3O4 microspheres-room temperature ionic liquid composite showing better performance than gold.  

PubMed

In recent decades, electrochemical detection of arsenic(III) has been undergoing revolutionary developments with higher sensitivity and lower detection limit. Despite great success, electrochemical detection of As(III) still depends heavily on noble metals (predominantly Au) in a strong acid condition, thus increasing the cost and hampering the widespread application. Here, we report a disposable platform completely free from noble metals for electrochemical detection of As(III) in drinking water under nearly neutral condition by square wave anodic stripping voltammetry. By combining the high adsorptivity of Fe3O4 microspheres toward As(III) and the advantages of room temperature ionic liquid (RTIL), the Fe3O4-RTIL composite modified screen-printed carbon electrode (SPCE) showed even better electrochemical performance than commonly used noble metals. Several ionic liquids with different viscosities and surface tensions were found to have a different effect on the voltammetric behavior toward As(III). Under the optimized conditions, the Fe3O4-RTIL composites offered direct detection of As(III) within the desirable range (10 ppb) in drinking water as specified by the World Health Organization (WHO), with a detection limit (3? method) of 8 × 10(-4) ppb. The obtained sensitivity was 4.91 ?A ppb(-1), which is the highest as far as we know. In addition, a possible mechanism for As(III) preconcentration based on adsorption has been proposed and supported by designed experiments. Finally, this platform was successfully applied to analyzing a real sample collected from Inner Mongolia, China. PMID:23374085

Gao, Chao; Yu, Xin-Yao; Xiong, Shi-Quan; Liu, Jin-Huai; Huang, Xing-Jiu

2013-03-01

143

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

PubMed

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

2014-10-23

144

Exploring the photophysics of curcumin in zwitterionic micellar system: an approach to control ESIPT process in the presence of room temperature ionic liquids (RTILs) and anionic surfactant.  

PubMed

In this manuscript, we have modulated the photophysical properties of curcumin in a zwitterionic (N-hexadecyl-N,N-dimethylammonio-1-propanesulfonate (SB-16)) micellar aggregates with addition of room temperature ionic liquids (RTILs) as well as commonly used anionic surfactant (SDS), using steady-state and time-resolved spectroscopic techniques. To modulate the photophysics, first we studied its interaction with an SB-16 micellar system, then to further exploit its photophysics, three RTILs (EmimES, EmimBS, EmimHS) with variation of alkyl chain lengths as well as SDS were used. It is observed that the rate of degradation of curcumin is drastically decreased after partitioning into the zwitterionic micellar system. It is shown that the dynamics of excited state intramolecular proton transfer (ESIPT) processes can be controlled by using those RTILs and SDS. Our study also reveals that the hindrance of nonradiative processes of curcumin, i.e., ESIPT is more pronounced in the case of RTIL containing a long alkyl chain compared to a small one. However, most interestingly the addition of long chain (dodecyl) anionic surfactant (SDS) promotes the ESIPT process of curcumin. We have also studied the effect of the addition of inorganic salt and compared the results with RTILs. The present work demonstrates an effort to decipher the photophysics of curcumin in zwitterionic micellar systems by monitoring its excited state dynamics. PMID:24617495

Banerjee, Chiranjib; Ghosh, Surajit; Mandal, Sarthak; Kuchlyan, Jagannath; Kundu, Niloy; Sarkar, Nilmoni

2014-04-01

145

Electrodeposition of aluminium and aluminium-copper alloys from a room temperature ionic liquid electrolyte containing aluminium chloride and triethylamine hydrochloride  

NASA Astrophysics Data System (ADS)

The electrodeposition of Al and Al-Cu binary alloys on to gold substrates from a room temperature ionic liquid electrolyte containing AlCl3-Et3NHCl was studied. The electrochemical behavior of the electrolyte and the mechanism of deposition were investigated through cyclic voltammetry (CV), and the properties of deposits obtained were assessed by scanning electron microscopy with energy dispersive X-ray spectroscopy (SEM-EDS) and X-ray diffraction (XRD). Al of 70 ?m in thickness and an Al-Cu alloy of 30 ?m in thickness with 8at% copper were deposited from the electrolyte. SEM images of the deposits indicate that the Al deposit was smooth and uniform, whereas the Al-Cu deposit was nodular. The average crystalline size, as determined by XRD patterns, was found to be (30 ± 5) and (29 ± 5) nm, respectively, for Al and Al-Cu alloys. Potentiodynamic polarization (Tafel plots) and electrochemical impedance spectroscopic (EIS) measurements showed that Al-Cu alloys are more corrosion resistant than Al.

Suneesh, P. V.; Satheesh Babu, T. G.; Ramachandran, T.

2013-09-01

146

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

PubMed

A novel biosensor based on the silica-coated gold nanorods (GNRs@SiO(2)) and hydrophilic room temperature ionic liquid (RTIL) 1-butyl-3-methylimidazolium tetrafluroborate ([bmim][BF(4)]) was fabricated for the determination of hydrogen peroxide (H(2)O(2)) and nitrite. GNRs@SiO(2) can not only act as a binder to hinder [bmim][BF(4)] (RTIL) leaking from the electrode surface, but also provide a favorable microenvironment for direct electrochemistry of myoglobin (Mb). A pair of well-defined and quasi-reversible redox peaks of Mb was obtained at the GNRs@SiO(2)-Mb/RTIL-sol-gel composite film modified GCE (GNRs@SiO(2)-Mb/RTIL-sol-gel/GCE) through direct electron transfer between Mb and the underlying electrode. This biosensor showed an excellent electrocatalytic activity towards hydrogen peroxide and nitrite. The linear range for the determination of H(2)O(2) was from 0.2 to 180 microM with a detection limit of 0.12 microM based on the signal-to-noise ratio of 3. In addition, the biosensor also exhibited high selectivity, good reproducibility, and long-term stability. Therefore, this kind of composite film can provide an ideal matrix for protein immobilization and biosensor fabrication. PMID:19782218

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

2009-11-15

147

Theinfluence of a hierarchical porous carbon network on the coherent dynamics of a nanoconfined room temperature ionic liquid: A neutron spin echo and atomistic simulation investigation  

SciTech Connect

The molecular-scale dynamic properties of the room temperature ionic liquid (RTIL) 1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide, or [C4mim+ ][Tf2N ], confined in hierarchical microporous mesoporous carbon, were investigated using neutron spin echo (NSE) and molecular dynamics (MD) simulations. Both NSE and MD reveal pronounced slowing of the overall collective dynamics, including the presence of an immobilized fraction of RTIL at the pore wall, on the time scales of these approaches. A fraction of the dynamics, corresponding to RTIL inside 0.75 nm micropores located along the mesopore surfaces, are faster than those of RTIL in direct contact with the walls of 5.8 nm and 7.8 nm cylindrical mesopores. This behavior is ascribed to the near-surface confined-ion density fluctuations resulting from the ion ion and ion wall interactions between the micropores and mesopores as well as their confinement geometries. Strong micropore RTIL interactions result in less-coordinated RTIL within the micropores than in the bulk fluid. Increasing temperature from 296 K to 353 K reduces the immobilized RTIL fraction and results in nearly an order of magnitude increase in the RTIL dynamics. The observed interfacial phenomena underscore the importance of tailoring the surface properties of porous carbons to achieve desirable electrolyte dynamic behavior, since this impacts the performance in applications such as electrical energy storage devices.

Banuelos, Jose Leo [ORNL; Feng, Guang [ORNL; Fulvio, Pasquale F [ORNL; Li, Song [Vanderbilt University, Nashville; Rother, Gernot [ORNL; Arend, Nikolas [ORNL; Faraone, Antonio [National Institute of Standards and Technology (NIST); Dai, Sheng [ORNL; Cummings, Peter T [ORNL; Wesolowski, David J [ORNL

2014-01-01

148

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.

149

Temperature-dependent electronic and vibrational structure of the 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)amide room-temperature ionic liquid surface: a study with XPS, UPS, MIES, and HREELS.  

PubMed

The near-surface structure of the room-temperature ionic liquid 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)amide has been investigated as a function of temperature between 100 and 620 K. We used a combination of photoelectron spectroscopies (XPS and UPS), metastable induced electron spectroscopy (MIES), and high-resolution electron energy loss spectroscopy (HREELS). The valence band and HREELS spectra are interpreted on the basis of density functional theory (DFT) calculations. At room temperature, the most pronounced structures in the HREELS, UPS, and MIES spectra are related to the CF3 group in the anion. Spectral changes observed at 100 K are interpreted as a change of the molecular orientation at the outermost surface, when the temperature is lowered. At elevated temperatures, early volatilization, starting at 350 K, is observed under reduced pressure. PMID:17474703

Krischok, S; Eremtchenko, M; Himmerlich, M; Lorenz, P; Uhlig, J; Neumann, A; Ottking, R; Beenken, W J D; Höfft, O; Bahr, S; Kempter, V; Schaefer, J A

2007-05-10

150

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.

2012-03-01

151

Room temperature ionic liquid-based dispersive liquid phase microextraction for the separation/preconcentration of trace Cd(2+) as 1-(2-pyridylazo)-2-naphthol (PAN) complex from environmental and biological samples and determined by FAAS.  

PubMed

The current work develops a new green methodology for the separation/preconcentration of cadmium ions (Cd(2+)) using room temperature ionic liquid-dispersive liquid phase microextraction (RTIL-DLME) prior to analysis by flame atomic absorption spectrometry with microsample introduction system. Room temperature ionic liquids (RTIL) are considered "Green Solvents" for their thermally stable and non-volatile properties, here 1-butyl-3-methylimidazolium hexafluorophosphate [C4mim][PF6] was used as an extractant. The preconcentration of Cd(2+) in different waters and acid digested scalp hair samples were complexed with 1-(2-pyridylazo)-2-naphthol and extracted into the fine drops of RTILs. Some significant factors influencing the extraction efficiency of Cd(2+) and its subsequent determination, including pH, amount of ligand, volume of RTIL, dispersant solvent, sample volume, temperature, and incubation time were investigated in detail. The limit of detection and the enhancement factor under the optimal conditions were 0.05 ?g/L and 50, respectively. The relative standard deviation of 100 ?g/L Cd(2+) was 4.3 %. The validity of the proposed method was checked by determining Cd(2+) in certified reference material (TM-25.3 fortified water). The sufficient recovery (>98 %) of Cd(2+) with the certified value. The mean concentrations of Cd in lake water 13.2, waste water 15.7 and hair sample 16.8 ?g/L, respectively and the developed method was applied satisfactorily to the preconcentration and determination of Cd(2+) in real samples. PMID:24197606

Khan, Sumaira; Soylak, Mustafa; Kazi, Tasneem Gul

2013-12-01

152

Cycling and rate performance of Li–LiFePO 4 cells in mixed FSI–TFSI room temperature ionic liquids  

Microsoft Academic Search

A study is conducted of the performance of lithium iron(II) phosphate, LiFePO4, as a cathode material in a lithium secondary battery that features an ionic liquid electrolyte solution and a metallic lithium anode. The electrolyte solution comprises an ionic liquid of a N-methyl-N-alkyl-pyrrolidinium (alkyl=n-propyl or n-butyl) cation and either the bis(fluorosulfonyl)imide [(FSO2)2N?] or bis(trifluoromethanesulfonyl)imide [(F3CSO2)2N?] anion, together with 0.5molkg?1 of

A. P. Lewandowski; A. F. Hollenkamp; S. W. Donne; A. S. Best

2010-01-01

153

The formation of high-order polybromides in a room-temperature ionic liquid: from monoanions ([Br5 ](-) to [Br11 ](-) ) to the isolation of [PC16 H36 ]2 [Br24 ] as determined by van der Waals Bonding Radii.  

PubMed

An unprecedented diversity of high-order bromine catenates (anionic polybromides) was generated in a tetraalkylphosphonium-based room temperature ionic liquid system. Raman spectroscopy was used to identify polybromide monoanions ranging from [Br5 ](-) to [Br11 ](-) in the bulk solution, while single-crystal X-ray diffraction identified extended networks of linked [Br11 ](-) units, forming a previously unknown polymeric [Br24 ](2-) dianion. This represents the largest polybromide species identified to date. In combination with recent work, this suggests that other, higher order molecular polybromide ions might be isolated. PMID:25487061

Easton, Max E; Ward, Antony J; Hudson, Toby; Turner, Peter; Masters, Anthony F; Maschmeyer, Thomas

2015-02-01

154

Photoinduced electron transfer (PET) from N, N-dimethylaniline to 7-amino Coumarin dyes in a room temperature ionic liquid (RTIL): Slowing down of electron transfer rate compared to conventional solvent  

NASA Astrophysics Data System (ADS)

In this Letter we have investigated the photoinduced electron transfer (PET) in a protic room temperature ionic liquid (PRTIL) comprised of non-aromatic cation and anion, N, N-dimethyl ethanol ammonium formate (DAF) to investigate how the dynamics of PET is affected in RTIL compared to other solvents. The photoinduced electron transfer rate in the ionic liquid DAF decreases by an order of magnitude upon going from the conventional solvent acetonitrile. We have observed saturation, i.e., a Rehm-Weller type of behaviour in the electron transfer rate. The ET rate ( k q) vs. -?G 0 plot shows saturation to a diffusion-controlled value at the higher exergonicity region.

Sarkar, Souravi; Pramanik, Rajib; Seth, Debabrata; Setua, Palash; Sarkar, Nilmoni

2009-07-01

155

Ionic liquids as novel solvents for ionic polymer transducers  

Microsoft Academic Search

The use of ionic liquids as solvents for ionic polymer (specifically, Nafion) transducers is demonstrated. Ionic liquids are attractive for this application because of their high inherent stability. Ionic liquids are salts that exist as liquids at room temperature and have no measureable vapor pressure. Therefore, the use of ionic liquids as solvents for ionic polymer transducers can eliminate the

Matthew D. Bennett; Donald J. Leo

2004-01-01

156

Biocatalytic transformations in ionic liquids  

Microsoft Academic Search

Room temperature ionic liquids are non-volatile, thermally stable and highly polar; they are also moderately hydrophilic solvents. Here, we discuss their use as reaction media for biocatalysis. Enzymes of widely diverging types are catalytically active in ionic liquids or aqueous biphasic ionic liquid systems. Lipases, in particular, maintain their activity in anhydrous ionic liquid media; the (enantio)selectivity and operational stability

Fred van Rantwijk; Rute Madeira Lau; Roger A Sheldon

2003-01-01

157

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

2011-01-01

158

Ionic Liquids in Chemical Analysis  

Microsoft Academic Search

Room-temperature ionic liquids are salts with a melting point close to or below room temperature. They form liquids composed in the majority of ions. This gives these materials the potential to behave very differently when they are used as solvents compared to conventional molecular liquids. The search for their application is growing in every area of analytical chemistry—electrochemistry, chromatography, electrophoresis,

Mihkel Koel

2005-01-01

159

Synthesis of ionic liquids  

DOEpatents

Ionic compounds which are liquids at room temperature are formed by the method of mixing a neutral organic ligand with the salt of a metal cation and its conjugate anion. The liquids are hydrophobic, conductive and stable and have uses as solvents and in electrochemical devices.

Dai, Sheng (Knoxville, TN); Luo, Huimin (Knoxville, TN)

2011-11-01

160

Synthesis of ionic liquids  

DOEpatents

Ionic compounds which are liquids at room temperature are formed by the method of mixing a neutral organic liqand with the salt of a metal cation and its conjugate anion. The liquids are hydrophobic, conductive and stable and have uses as solvents and in electrochemical devices.

Dai, Sheng [Knoxville, TN; Luo, Huimin [Knoxville, TN

2008-09-09

161

Synthesis of room-temperature ionic liquids with the weakly coordinating [Al(ORF)4]- anion (RF=C(H)(CF3)2) and the determination of their principal physical properties.  

PubMed

A large series of ionic liquids (ILs) based on the weakly coordinating alkoxyaluminate [Al(hfip)(4)](-) (hfip: hexafluoroisopropoxy) with classical as well as functionalized cations were prepared, and their principal physical properties determined. Melting points are between 0 ([C(4)MMIM][Al(hfip)(4)]) and 69 °C ([C(3)MPip][Al(hfip)(4)]); three qualify as room-temperature ILs (RTILs). Crystal structures for six ILs were determined; their structural parameters and anion-cation contacts are compared here with known ILs, with a special focus on their influence on physical properties. Moreover, the biodegradability of the compounds was investigated by using the closed-bottle and the manometric respirometry test. Temperature-dependent viscosities and conductivities were measured between 0 and 80 °C, and described by either the Vogel-Fulcher-Tammann (VFT) or the Arrhenius equations. Moreover, conductivities and viscosities were investigated in the context of the molecular volume, V(m). Physical property-V(m) correlations were carried out for various temperatures, and the temperature dependence of the molecular volume was analyzed by using crystal structure data and DFT calculations. The IL ionicity was investigated by Walden plots; according to this analysis, [Al(hfip)(4)](-) ILs may be classified as "very good to good ILs"; while [C(2)MIM][Al(hfip)(4)] is a better IL than [C(2)MIM][NTf(2)]. The dielectric constants of ten [Al(hfip)(4)](-) ILs were determined, and are unexpectedly high (?(r)=11.5 to 16.8). This could be rationalized by considering additional calculated dipole moments of the structures frozen in the solid state by DFT. The determination of hydrogen gas solubility in [Al(hfip)(4)](-) RTILs by high-pressure NMR spectroscopy revealed very high hydrogen solubilities at 25 °C and 1 atm. These results indicate the significant potential of this class of ILs in manifold applications. PMID:20886467

Bulut, Safak; Klose, Petra; Huang, Mian-Mian; Weingärtner, Hermann; Dyson, Paul J; Laurenczy, Gábor; Friedrich, Christian; Menz, Jakob; Kümmerer, Klaus; Krossing, Ingo

2010-11-22

162

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.  

PubMed

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 ± 6.27 nm) with high density (682 particles µm(-2)) were obtained. Under optimized conditions, a linear range from 2.0 to 44.0 × 10(-9) mol L(-1) and a limit of detection (LOD) of 0.6 × 10(-9) mol L(-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

2015-01-01

163

New Insight of Coordination and Extraction of Uranium(VI) with N-Donating Ligands in Room Temperature Ionic Liquids: N,N'-Diethyl-N,N'-ditolyldipicolinamide as a Case Study.  

PubMed

Room temperature ionic liquids (RTILs) represent a recent new class of solvents applied in liquid/liquid extraction based nuclear fuel reprocessing, whereas the related coordination chemistry and detailed extraction processes are still not well understood and remain of deep fundamental interest. The work herein provides a new insight of coordination and extraction of uranium(VI) with N-donating ligands, e.g., N,N'-diethyl-N,N'-ditolyldipicolinamide (EtpTDPA), in commonly used RTILs. Exploration of the extraction mechanism, speciation analyses of the extracted U(VI), and crystallographic studies of the interactions of EtpTDPA with U(VI) were performed, including the first structurally characterized UO2(EtpTDPA)2(NTf2) and UO2(EtpTDPA)2(PF6)2 compounds and a first case of crystallographic differentiation between the extracted U(VI) complexes in RTILs and in molecular solvents. It was found that in RTILs two EtpTDPA molecules coordinate with one U(VI) ion through the carbonyl and pyridine nitrogen moieties, while NTf2(-) and PF6(-) act as counterions. The absence of NO3(-) in the complexes is coincident with a cation-exchange extraction. In contrast, both the extracted species and extraction mechanisms are greatly different in dichloromethane, in which UO2(2+) coordinates in a neutral complex form with one EtpTDPA molecule and two NO3(-) cations. In addition, the complex formation in RTILs is independent of the cation exchange since incorporating UO2(NO3)2, EtpTDPA, and LiNTf2 or KPF6 in a solution also produces the same complex as that in RTILs, revealing the important roles of weakly coordinating anions on the coordination chemistry between U(VI) and EtpTDPA. These findings suggest that cation-exchange extraction mode for ILs-based extraction system probably originates from the supply of weakly coordinating anions from RTILs. Thus the coordination of uranium(VI) with extractants as well as the cation-exchange extraction mode may be potentially changed by varying the counterions of uranyl or introducing extra anions. PMID:25629464

Yuan, Li-Yong; Sun, Man; Mei, Lei; Wang, Lin; Zheng, Li-Rong; Gao, Zeng-Qiang; Zhang, Jing; Zhao, Yu-Liang; Chai, Zhi-Fang; Shi, Wei-Qun

2015-02-16

164

Electrically Switchable Capillarity of Ionic Liquids  

Microsoft Academic Search

Electrocapillarity is the basis of modern electrowetting. And room temperature ionic liquids, an increasingly important set of electrolytes and organic salts that are liquid at room temperature, are considered a novel class of electrowetting agents, because of non-significant vapor pressure, nonflammability, good thermal stability, and a wide useable temperature range. In this paper, a simple device has been fabricated to

Xiaodong Hu; Shiguo Zhang; Chao Qu; Qinghua Zhang; Liujin Lu; Xiangyuan Ma; Xiaoping Zhang; Youquan Deng

2012-01-01

165

Ionic liquids: applications in catalysis  

Microsoft Academic Search

The use of room temperature ionic liquids as either solvents or catalysts has been the subject of considerable recent attention because of the prospects for “green” catalysis. This paper presents a review of the potential applications of these unique liquid materials in industrial catalysis.

Dongbin Zhao; Min Wu; Yuan Kou; Enze Min

2002-01-01

166

3-Methylpiperidinium ionic liquids.  

PubMed

A wide range of room temperature ionic liquids based on the 3-methylpiperdinium cation core were produced from 3-methylpiperidine, which is a derivative of DYTEK® A amine. First, reaction with 1-bromoalkanes or 1-bromoalkoxyalkanes generated the corresponding tertiary amines (Rm?pip, R = alkyl or alkoxyalkyl); further quaternisation reactions with the appropriate methylating agents yielded the quaternary [Rmm?pip]X salts (X(-) = I(-), [CF3CO2](-) or [OTf](-); Tf = -SO2CF3), and [Rmm?pip][NTf2] were prepared by anion metathesis from the corresponding iodides. All [NTf2](-) salts are liquids at room temperature. [Rmm?pip]X (X(-) = I(-), [CF3CO2](-) or [OTf](-)) are low-melting solids when R = alkyl, but room temperature liquids upon introduction of ether functionalities on R. Neither of the 3-methylpiperdinium ionic liquids showed any signs of crystallisation, even well below 0 °C. Some related non-C-substituted piperidinium and pyrrolidinium analogues were prepared and studied for comparison. Crystal structures of 1-hexyl-1,3-dimethylpiperidinium tetraphenylborate, 1-butyl-3-methylpiperidinium bromide, 1-(2-methoxyethyl)-1-methylpiperidinium chloride and 1-(2-methoxyethyl)-1-methylpyrrolidinium bromide are reported. Extensive structural and physical data are collected and compared to literature data, with special emphasis on the systematic study of the cation ring size and/or asymmetry effects on density, viscosity and ionic conductivity, allowing general trends to be outlined. Cyclic voltammetry shows that 3-methylpiperidinium ionic liquids, similarly to azepanium, piperidinium or pyrrolidinium counterparts, are extremely electrochemically stable; the portfolio of useful alternatives for safe and high-performing electrolytes is thus greatly extended. PMID:25669485

Belhocine, Tayeb; Forsyth, Stewart A; Gunaratne, H Q Nimal; Nieuwenhuyzen, Mark; Nockemann, Peter; Puga, Alberto V; Seddon, Kenneth R; Srinivasan, Geetha; Whiston, Keith

2015-04-01

167

Phosphonium-based ionic liquids and uses  

DOEpatents

Phosphonium-based room temperature ionic liquids ("RTILs") were prepared. They were used as matrices for Matrix-Assisted Laser Desorption Ionization (MALDI) mass spectrometry and also for preparing samples of dyes for analysis.

Del Sesto, Rico E; Koppisch, Andrew T; Lovejoy, Katherine S; Purdy, Geraldine M

2014-12-30

168

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

2011-01-01

169

Ionic Liquids  

Microsoft Academic Search

Ionic liquids are receiving an upsurge of interest as green solvents; primarily as replacements for conventional media in\\u000a chemical processes. This review presents an overview of the chemistry that has been developed utilising ionic liquids as either\\u000a catalyst and\\/or solvent, with particular emphasis on processes that have been taken beyond the pre-competetive laboratory\\u000a stage and represent clean industrial technology with

J. D. Holbrey; K. R. Seddon

1999-01-01

170

THE JOURNAL OF CHEMICAL PHYSICS 139, 214701 (2013) The liquid surface of chiral ionic liquids as seen from molecular dynamics  

E-print Network

THE JOURNAL OF CHEMICAL PHYSICS 139, 214701 (2013) The liquid surface of chiral ionic liquids room-temperature ionic liquids (RTILs) derived from 1-n-butyl-3-methylimidazolium bromide ([bmim.1063/1.4833335] I. INTRODUCTION Room-temperature ionic liquids (RTILs) typically con- sist of bulky and asymmetric

Lisal, Martin

2013-01-01

171

Room temperature single-photon Source:Single-dye molecule fluorescence in Liquid Crystal host  

Microsoft Academic Search

We report on new approaches toward an implementation of an efficient, room temperature, deterministically polarized, single-photon source (SPS) on demand-a key hardware element for quantum information and quantum communication. Operation of a room temperature SPS is demonstrated via photon antibunching in the fluorescence from single terrylene-dye molecules embedded in a cholesteric liquid crystal host. Using oxygen-depleted liquid crystal hosts, dye-bleaching

Svetlana G. Lukishova; Ansgar W. Schmid; Andrew J. McNamara; Robert W. Boyd; Carlos R. Stroud

2003-01-01

172

Electrochemical transistors with ionic liquids for enzymatic sensing  

E-print Network

Electrochemical transistors with ionic liquids for enzymatic sensing Kevin J. Frasera , Sang Yoon and lactate. Room temperature ionic liquids (RTILs) are organic salts, which are liquid at ambient temperature to ionic liquids (ILs), IL ­ enzyme mixtures and a combination of these novel materials being used on OECTs

Lee, Hyowon

173

Sonochemistry and sonoluminescence in ionic liquids, molten salts, and concentrated electrolyte solutions  

E-print Network

Review Sonochemistry and sonoluminescence in ionic liquids, molten salts, and concentrated interesting liquids for studies involving sonochemistry, acoustic cavitation, and sonoluminescence. Recent on the effects of cavitation on some room-temperature ionic liquids, including the sonoluminescence spectra

Suslick, Kenneth S.

174

Biocatalysis in ionic liquids – advantages beyond green technology  

Microsoft Academic Search

In recent years researchers have started to explore a particular class of organic solvents called room temperature ionic liquids — or simply ionic liquids – to identify their unique advantages for biocatalysis. Because they lack vapour pressure, ionic liquids hold potential as green solvents. Furthermore, unlike organic solvents of comparable polarity, they often do not inactivate enzymes, which simplifies reactions

Romas J Kazlauskas

2003-01-01

175

ELECTROCHEMICAL STUDIES OF HEMIN IN IONIC LIQUIDS  

Technology Transfer Automated Retrieval System (TEKTRAN)

Ionic liquids (ILs), room temperature liquid organic salts, have gained prominence as alternative media for volatile organic solvents. Recent studies have shown that some enzymes tolerate ILs and have catalytic activities comparable to those obtained in molecular organic solvents. We have investig...

176

Application of Task-specific Ionic Liquids for Intensified Separations  

Microsoft Academic Search

Summary.  Ionic liquids offer tremendous opportunities to intensify reactions and separations in process technologies by tuning their\\u000a physical and chemical properties. Several ionic liquids are suitable for the separation of aromatic and aliphatic hydrocarbons.\\u000a CO2 absorption behavior was influenced by the functionalized chains appended to the room temperature ionic liquid (RTIL) cation.\\u000a Ionic liquids seem able to combine the chemical features

G. Wytze Meindersma; Lara M. Galán Sánchez; Antje R. Hansmeier; André B. de Haan

2007-01-01

177

Externally Wetted Ionic Liquid Thruster  

NASA Astrophysics Data System (ADS)

This paper presents initial developments of an electric propulsion system based on ionic liquid ion sources (ILIS). Propellants are ionic liquids, which are organic salts with two important characteristics; they remain in the liquid state at room temperature and have negligible vapor pressure, thus allowing their use in vacuum. The working principles of ILIS are similar to those of liquid metal ion sources (LMIS), in which a Taylor cone is electrostatically formed at the tip of an externally wetted needle while ions are emitted directly from its apex. ILIS have the advantage of being able to produce negative ions that have similar masses than their positive counterparts with similar current levels. This opens up the possibility of achieving plume electrical neutrality without electron emitters. The possible multiplexing of these emitters is discussed in terms of achievable thrust density for applications other than micro-propulsion.

Lozano, P.; Martinez-Sanchez, M.; Lopez-Urdiales, J. M.

2004-10-01

178

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.

179

Ionic Liquids to Replace Hydrazine  

NASA Technical Reports Server (NTRS)

A method for developing safe, easy-to-handle propellants has been developed based upon ionic liquids (ILs) or their eutectic mixtures. An IL is a binary combination of a typically organic cation and anion, which generally produces an ionic salt with a melting point below 100 deg C. Many ILs have melting points near, or even below, room temperature (room temperature ionic liquids, RTILs). More importantly, a number of ILs have a positive enthalpy of formation. This means the thermal energy released during decomposition reactions makes energetic ILs ideal for use as propellants. In this specific work, to date, a baseline set of energetic ILs has been identified, synthesized, and characterized. Many of the ILs in this set have excellent performance potential in their own right. In all, ten ILs were characterized for their enthalpy of formation, density, melting point, glass transition point (if applicable), and decomposition temperature. Enthalpy of formation was measured using a microcalorimeter designed specifically to test milligram amounts of energetic materials. Of the ten ILs characterized, five offer higher Isp performance than hydrazine, ranging between 10 and 113 seconds higher than the state-of-the-art propellant. To achieve this level of performance, the energetic cations 4- amino-l,2,4-triazolium and 3-amino-1,2,4-triazolium were paired with various anions in the nitrate, dicyanamide, chloride, and 3-nitro-l,2,4-triazole families. Protonation, alkylation, and butylation synthesis routes were used for creation of the different salts.

Koelfgen, Syri; Sims, Joe; Forton, Melissa; Allan, Barry; Rogers, Robin; Shamshina, Julia

2011-01-01

180

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

2009-01-01

181

Dynamics in Organic Ionic Liquids in Distinct Regions Using Charged and Uncharged Orientational Relaxation Probes  

E-print Network

, and therefore influence "task-specific" organic ionic liquids.13 The design of task-specific organic ionicDynamics in Organic Ionic Liquids in Distinct Regions Using Charged and Uncharged Orientational(trifluoromethanesulfonyl)imide (alkyl ) ethyl, butyl, hexyl, octyl) organic room temperature ionic liquids (RTIL). The two fluorescent

Fayer, Michael D.

182

Adsorption of imidazolium and pyridinium ionic liquids onto montmorillonite : characterization and thermodynamic calculations  

E-print Network

1 Adsorption of imidazolium and pyridinium ionic liquids onto montmorillonite : characterization generation ionic liquids (RTILs : BMImCl, OMImCl, AMImCl, BPyBr and OPyBr) were intercalated into the layered: Montmorillonite; Ionic liquids; Adsorption; Thermodynamic parameters 1. Introduction Room Temperature Ionic

Paris-Sud XI, Université de

183

Electronic dephasing in nonpolar room temperature liquids: UV photon echo pulse duration dependent measurements  

E-print Network

of liquid solvent­solute interactions using dye mol- ecules that absorb in the visible or near IR between the chromophore and the solvent. The dipoles may be permanent or induced. Ionic dye chromophores

Fayer, Michael D.

184

Aqueous, Room Temperature Electrochemical Deposition of Compact Si Films  

E-print Network

electrodeposition have employed either organic solvents,7­12 room temperature ionic liquids (RTILs),13­18 or high and photovoltaic devices, Li ion battery anodes, and corrosion-resistant coatings.1­4 Unfortunately, Si thin film

Suni, Ian Ivar

185

Use of ionic liquids as coordination ligands for organometallic catalysts  

DOEpatents

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)

2009-11-10

186

AN ELECTROSTATIC INTERPRETATION OF STRUCTURE-PROPERTY RELATIONSHIPS IN IONIC LIQUIDS  

E-print Network

AN ELECTROSTATIC INTERPRETATION OF STRUCTURE-PROPERTY RELATIONSHIPS IN IONIC LIQUIDS Mark N. Kobrak University of New York 2900 Bedford Ave. Brooklyn, NY 11210 ABSTRACT Room-temperature ionic liquids represent in molecular liquid theory, that of a molecular dipole moment, is in fact ill-defined for ionic materials

Kobrak, Mark N.

187

Double Layer in Ionic Liquids: Overscreening versus Crowding Martin Z. Bazant,1  

E-print Network

Double Layer in Ionic Liquids: Overscreening versus Crowding Martin Z. Bazant,1 Brian D. Storey,2 of solvent-free ionic liquids and use it to predict the structure of the electrical double layer. The model simulations and experiments on room-temperature ionic liquids, using a correlation length of order the ion

Bazant, Martin Z.

188

Ionic liquids in catalysis  

Microsoft Academic Search

The current state of the art of the application of ionic liquids in catalysis is reviewed. The review selects examples of the different ways in which ionic liquids have been applied in catalysis, i.e. as the catalyst itself, as a co-catalyst or catalyst activator, as the source of a new ligand for a catalytic metal centre, or just as the

Tom Welton

2004-01-01

189

An imidazolium based ionic liquid electrolyte for lithium batteries  

Microsoft Academic Search

An electrolyte for lithium batteries based on the ionic liquid 3-methy-1-propylimidazolium bis(trifluoromethysulfony)imide (PMIMTFSI) complexed with lithium bis(trifluoromethysulfony)imide (LiTFSI) at a molar ratio of 1:1 has been investigated. The electrolyte shows a high ionic conductivity (?1.2×10?3Scm?1) at room temperature. Over the whole investigated temperature range the ionic conductivity is more than one order of magnitude higher than for an analogue electrolyte

Jae-Kwang Kim; Aleksandar Matic; Jou-Hyeon Ahn; Per Jacobsson

2010-01-01

190

Novel imidazolium chiral ionic liquids that contain a urea functionality  

Microsoft Academic Search

Nine chiral room temperature ionic liquids (RTILs), which contain a chiral moiety and a urea functionality bonded to a imidazolium 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 1-(3-aminopropyl)imidazole and amino acid ester derived isocyanates. We

Bukuo Ni; Allan D. Headley

2006-01-01

191

hal-00132485,version1-21Feb2007 Liquid nitrogen to room temperature thermometry using niobium nitride thin films  

E-print Network

hal-00132485,version1-21Feb2007 Liquid nitrogen to room temperature thermometry using niobium´eel, CNRS-UJF, 25 avenue des Martyrs, 38042 Grenoble, France (Dated: February 21, 2007) Niobium nitride thin, the interesting properties of niobium nitride (NbN) as well as amorphous Nb-Si have been ex- tensively used

Boyer, Edmond

192

For session on "Structure and Properties of Ionic Liquids and Molten Salts" Ionic Liquids, quasi-ionic liquids, and quasi-liquid ionics, all with high  

E-print Network

For session on "Structure and Properties of Ionic Liquids and Molten Salts" Ionic Liquids, quasi-ionic liquids, and quasi-liquid ionics, all with high ionic liquids are prepared by proton transfer from a Bronsted acid

Angell, C. Austen

193

Chiral Ionic Liquid that Functions as Both Solvent and Chiral Selector for the Determination of  

E-print Network

Chiral Ionic Liquid that Functions as Both Solvent and Chiral Selector for the Determination synthesized both enantiomers of a novel chiral ionic liquid, (R)- and (S)-[(3-chloro-2-hy- droxypropyl), is liquid at room temperature (glass transition temperature of -58.4 °C), and exhibits strong enantiomeric

Reid, Scott A.

194

Acetonitrile Drastically Boosts Conductivity of Ionic Liquids  

E-print Network

We apply a new methodology in the force field generation (PCCP 2011, 13, 7910) to study the binary mixtures of five imidazolium-based room-temperature ionic liquids (RTILs) with acetonitrile (ACN). The investigated RTILs are composed of tetrafluoroborate (BF4) anion and dialkylimidazolium cations, where one of the alkyl groups is methyl for all RTILs, and the other group is different for each RTILs, being ethyl (EMIM), butyl (BMIM), hexyl (HMIM), octyl (OMIM), and decyl (DMIM). Specific densities, radial distribution functions, ionic cluster distributions, heats of vaporization, diffusion constants, shear viscosities, ionic conductivities, and their correlations are discussed. Upon addition of ACN, the ionic conductivity of RTILs is found to increase by more than 50 times, that significantly exceeds an impact of most known solvents. Remarkably, the sharpest conductivity growth is found for the long-tailed imidazolium-based cations. This new fact motivates to revisit an application of these binary systems as a...

Chaban, Vitaly V; Kalugin, Oleg N; Prezhdo, Oleg V

2012-01-01

195

A room-temperature processed parylene-patterned helical ionic polymer-metal composite spring actuator with selectable active region  

NASA Astrophysics Data System (ADS)

This paper presents a novel helical ionic polymer metal composite (IPMC) spring actuator. A room-temperature fabrication process is developed to selectively grow in situ nickel metal electrode on a coiled Nafion strip, which is patterned with parylene as a masking layer to delineate the inactive region. This method allows the helical spring actuator to be shaped in a near-constant temperature environment and minimizes the residual stress effect on the Nafion polymer, compared to other processes using thermal treatment. The developed process ensures that short-circuiting never occurs between the outer and inner electrodes of the actuator, and the active region can be designed via parylene patterning. The motion of the fabricated spring actuator is measured, and the maximal displacement reaches 1 mm at the endpoint of the spring under a 0.1 Hz 6 V square wave actuation. A microtensile experiment is performed for characterizing the stress and strain relation. The resulting Young’s moduli of the Nafion and fabricated IPMC strips are 183 and 227 MPa, respectively. Analysis based on Castigliano’s theorem is executed to derive equations related to the moment, force output, strain energy, and displacement of an arbitrary point of the fabricated spring actuator. Results show the produced moment, force, and strain energy of the operated spring actuator are in the level of 1.5 ?N m, 300 mN, and 20-100 ?J, respectively.

Feng, Guo-Hua; Zhan, Zhen-Hua

2014-04-01

196

Photochemistry in Ionic Liquids  

Microsoft Academic Search

\\u000a The use of ionic liquids in applications such as electrochemistry [1], organic synthesis [2, 3], and separation science [4] is fast becoming a mature area of study, and many data have now been accumulated. In contrast, study of the physical properties\\u000a of ionic liquids has lagged behind the advances made in these more applied areas of chemistry. To this end,

Charles M. Gordon

197

Applications of ionic liquids.  

PubMed

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

2012-06-01

198

Low Temperature Reduction of Alumina Using Fluorine Containing Ionic Liquids  

Microsoft Academic Search

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

R. G. Reddy

2007-01-01

199

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

2010-01-01

200

Sulfonium-based Ionic Liquids Incorporating the Allyl Functionality  

PubMed Central

A series of sulfonium halides bearing allyl groups have been prepared and characterized. Anion metathesis with Li[Tf2N] and Ag[N(CN)2] resulted in sulfonium-based ionic liquids which exhibit low viscosities at room temperature. The solid state structure of one of the halide salts was determined by single crystal X-ray diffraction.

Zhao, Dongbin; Fei, Zhaofu; Ang, Wee Han; Dyson, Paul J.

2007-01-01

201

Revisiting ether-derivatized imidazolium-based ionic liquids.  

PubMed

A series of ether-derivatized imidazolium halides have been prepared and characterized. Contrary to literature reports, they are all crystalline solids and have melting points well above room temperature (50-100 degrees C). Single crystals of the imidazolium salts, obtained in situ by slow cooling from their molten state to room temperature, were analyzed by X-ray crystallography, revealing various anion-cation interactions in the solid state. Exchange of the halides with [Tf(2)N]- yielded room temperature ionic liquids with viscosities that are comparable to related 1-alkyl-3-methylimidazolium ionic liquids. Density functional theory combined with IR spectroscopy has been used to analyze the role of functionalization of the imidazolium side chain on the formation of the molecular and supramolecular structure of the compounds and its possible impact on their physical properties. PMID:17676796

Fei, Zhaofu; Ang, Wee Han; Zhao, Dongbin; Scopelliti, Rosario; Zvereva, Elena E; Katsyuba, Sergey A; Dyson, Paul J

2007-08-30

202

Superoxide Electrochemistry in an Ionic Liquid Inas M. AlNashef, Matthew L. Leonard, Michael A. Matthews,* and  

E-print Network

Superoxide Electrochemistry in an Ionic Liquid Inas M. AlNashef, Matthew L. Leonard, Michael A) as the supporting electrolyte at elevated pressure and (2) in a room-temperature ionic liquid, 1-n-butyl- 3-temperature ionic liquids (RTILs) as substitute solvents in Green chemistry, with the emphasis on organic synthesis

Weidner, John W.

203

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.

None

2010-07-01

204

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

2013-12-01

205

FINAL REPORT: Room Temperature Hydrogen Storage in Nano-Confined Liquids  

SciTech Connect

DOE continues to seek solid-state hydrogen storage materials with hydrogen densities of ?6 wt% and ?50 g/L that can deliver hydrogen and be recharged at room temperature and moderate pressures enabling widespread use in transportation applications. Meanwhile, development including vehicle engineering and delivery infrastructure continues for compressed-gas hydrogen storage systems. Although compressed gas storage avoids the materials-based issues associated with solid-state storage, achieving acceptable volumetric densities has been a persistent challenge. This project examined the possibility of developing storage materials that would be compatible with compressed gas storage technology based on enhanced hydrogen solubility in nano-confined liquid solvents. These materials would store hydrogen in molecular form eliminating many limitations of current solid-state materials while increasing the volumetric capacity of compressed hydrogen storage vessels. Experimental methods were developed to study hydrogen solubility in nano-confined liquids. These methods included 1) fabrication of composites comprised of volatile liquid solvents for hydrogen confined within the nano-sized pore volume of nanoporous scaffolds and 2) measuring the hydrogen uptake capacity of these composites without altering the composite composition. The hydrogen storage capacities of these nano-confined solvent/scaffold composites were compared with bulk solvents and with empty scaffolds. The solvents and scaffolds were varied to optimize the enhancement in hydrogen solubility that accompanies confinement of the solvent. In addition, computational simulations were performed to study the molecular-scale structure of liquid solvent when confined within an atomically realistic nano-sized pore of a model scaffold. Confined solvent was compared with similar simulations of bulk solvent. The results from the simulations were used to formulate a mechanism for the enhanced solubility and to guide the experiments. Overall, the combined experimental measurements and simulations indicate that hydrogen storage based on enhanced solubility in nano-confined liquids is unlikely to meet the storage densities required for practical use. Only low gravimetric capacities of < 0.5 wt% were achieved. More importantly, solvent filled scaffolds had lower volumetric capacities than corresponding empty scaffolds. Nevertheless, several of the composites measured did show significant (>~ 5x) enhanced hydrogen solubility relative to bulk solvent solubility, when the hydrogen capacity was attributed only to dissolution in the confined solvent. However, when the hydrogen capacity was compared to an empty scaffold that is known to store hydrogen by surface adsorption on the scaffold walls, including the solvent always reduced the hydrogen capacity. For the best composites, this reduction relative to an empty scaffold was ~30%; for the worst it was ~90%. The highest capacities were obtained with the largest solvent molecules and with scaffolds containing 3- dimensionally confined pore geometries. The simulations suggested that the capacity of the composites originated from hydrogen adsorption on the scaffold pore walls at sites not occupied by solvent molecules. Although liquid solvent filled the pores, not all of the adsorption sites on the pore walls were occupied due to restricted motion of the solvent molecules within the confined pore space.

VAJO, JOHN

2014-06-12

206

Ionic liquids as electrolytes for Li-ion batteries—An overview of electrochemical studies  

Microsoft Academic Search

The paper reviews properties of room temperature ionic liquids (RTILs) as electrolytes for lithium and lithium-ion batteries. It has been shown that the formation of the solid electrolyte interface (SEI) on the anode surface is critical to the correct operation of secondary lithium-ion batteries, including those working with ionic liquids as electrolytes. The SEI layer may be formed by electrochemical

Andrzej Lewandowski; Agnieszka ?widerska-Mocek

2009-01-01

207

Confinement driven effects in a room temperature ferroelectric liquid crystal: X-ray, linear and non-linear dielectric investigations  

Microsoft Academic Search

We present results of X-ray, linear and non-linear dielectric constant measurements on a room temperature ferroelectric liquid crystalline phase in its bulk form and upon confinement in an Anopore membrane. The used material exhibits smectic C* (SmC*) helical pitch of p???200?nm, which is comparable to the pore dimension of the membrane. X-ray measurements show several interesting results including unusually strong

M. Vijay Kumar; S. Krishna Prasad; D. S. Shankar Rao; E. P. Pozhidaev

2012-01-01

208

Ionic liquids behave as dilute electrolyte solutions.  

PubMed

We combine direct surface force measurements with thermodynamic arguments to demonstrate that pure ionic liquids are expected to behave as dilute weak electrolyte solutions, with typical effective dissociated ion concentrations of less than 0.1% at room temperature. We performed equilibrium force-distance measurements across the common ionic liquid 1-butyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide ([C4mim][NTf2]) using a surface forces apparatus with in situ electrochemical control and quantitatively modeled these measurements using the van der Waals and electrostatic double-layer forces of the Derjaguin-Landau-Verwey-Overbeek theory with an additive repulsive steric (entropic) ion-surface binding force. Our results indicate that ionic liquids screen charged surfaces through the formation of both bound (Stern) and diffuse electric double layers, where the diffuse double layer is comprised of effectively dissociated ionic liquid ions. Additionally, we used the energetics of thermally dissociating ions in a dielectric medium to quantitatively predict the equilibrium for the effective dissociation reaction of [C4mim][NTf2] ions, in excellent agreement with the measured Debye length. Our results clearly demonstrate that, outside of the bound double layer, most of the ions in [C4mim][NTf2] are not effectively dissociated and thus do not contribute to electrostatic screening. We also provide a general, molecular-scale framework for designing ionic liquids with significantly increased dissociated charge densities via judiciously balancing ion pair interactions with bulk dielectric properties. Our results clear up several inconsistencies that have hampered scientific progress in this important area and guide the rational design of unique, high-free-ion density ionic liquids and ionic liquid blends. PMID:23716690

Gebbie, Matthew A; Valtiner, Markus; Banquy, Xavier; Fox, Eric T; Henderson, Wesley A; Israelachvili, Jacob N

2013-06-11

209

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

2007-05-29

210

Chemical propulsion using ionic liquids.  

PubMed

Chemical propulsion generates motion by directly converting locally stored chemical energy into mechanical energy. Here, we describe chemically driven autonomous motion generated by using imidazolium-based ionic liquids on a water surface. From measurements of the driving force of a locomotor loaded with an ionic liquid and observations of convection on the water surface originating from the ionic liquid container of the locomotor, the driving mechanism of the motion is found to be due to the Marangoni effect that arises from the anisotropic distribution of ionic liquids on the water surface. The maximum driving force and the force-generation duration are determined by the surface activity of the ionic liquid and the solubility of the ionic liquid in water, respectively. Because of the special properties of ionic liquids, a chemical locomotor driven by ionic liquids is promising for realizing autonomous micromachines and nanomachines that are safe and environmentally friendly. PMID:23398242

Tsuchitani, Shigeki; Takagi, Nobuhiro; Kikuchi, Kunitomo; Miki, Hirobumi

2013-03-01

211

Task-specific ionic liquids.  

PubMed

In recent years, ionic liquids have attracted the attention of many chemists as a result of their unique properties as solvents for chemical transformations. The focus of this Minireview is on applications of so-called "task-specific" ionic liquids, whereby the role of the ionic liquid goes beyond that of a solvent. Such ionic liquids find application in a wide range of areas, including catalysis, synthesis, gas absorption, and analysis. PMID:20229544

Giernoth, Ralf

2010-04-01

212

Electrically switchable multi-stable cholesteric liquid crystal based on chiral ionic liquid.  

PubMed

A multi-stable and electrically switchable cholesteric liquid crystal based on chiral ionic liquid is demonstrated. The cholesteric liquid crystal can be switched among the planar texture, focal conic texture, wide-band reflected state, and fingerprint texture by applying specific electric fields. Each of these four states exists stably for several hours without any obvious change observed at room temperature. The electro-optical properties and driving scheme of the cholesteric liquid crystal are also reported. PMID:25502999

Lu, Hongbo; Xu, Wei; Song, Zhigang; Zhang, Shanna; Qiu, Longzhen; Wang, Xianghua; Zhang, Guobing; Hu, Juntao; Lv, Guoqiang

2014-12-15

213

Enzyme catalysis in ionic liquids  

Microsoft Academic Search

Ionic liquids offer new possibilities for the application of solvent engineering to biocatalytic reactions. Although in many cases ionic liquids have simply been used to replace organic solvents, they have often led to improved process performance. Unlike conventional organic solvents, ionic liquids possess no vapor pressure, are able to dissolve many compounds, and can be used to form two-phase systems

Udo Kragl; Marrit Eckstein; Nicole Kaftzik

2002-01-01

214

Ionic liquids to the rescue? Overcoming the ionic conductivity limitations of polymer electrolytes  

Microsoft Academic Search

Polymer electrolytes – solid polymeric membranes with dissolved salts – are being intensively studied for use in all-solid-state lithium-metal-polymer (LMP) batteries to power consumer electronic devices. The low ionic conductivity at room temperature of existing polymer electrolytes, however, has seriously hindered the development of such batteries for many applications. The incorporation of salts molten at room temperature (room temperature ionic

Joon-Ho Shin; Wesley A. Henderson; Stefano Passerini

2003-01-01

215

Solubility and Aggregation of Charged Surfactants in Ionic Liquids Lang G. Chen and Harry Bermudez*  

E-print Network

, a connection between the solubility of the surfactant and the physical properties of the underlying ionic the synthesis and characterization of many new IL compounds to build and validate structure-property relation Supporting Information ABSTRACT: Room-temperature ionic liquids (ILs) exhibit a unique set of properties

216

Synthesis and characterization of two ionic liquids with emphasis on their chemical stability towards metallic lithium  

Microsoft Academic Search

Two room temperature ionic liquids (RTILs) without acidic protons, based on different cationic species (1-n-butyl-2,3-dimethylimidazolium) (BMMI) and N-n-butyl-N-methylpiperidinium (BMP) using (CF3SO2)2N? (TFSI) as anion, were prepared by quaternization of their respective amines with an appropriate alkyl halide, followed by ion exchange reaction. All relevant properties of these ionic liquids, such as, thermal stability, density, viscosity, electrochemical behavior, ionic conductivity and

Fernanda F. C. Bazito; Yoshio Kawano; Roberto M. Torresi

2007-01-01

217

This journal is c The Royal Society of Chemistry 2011 Chem. Soc. Rev., 2011, 40, 13471357 1347 Multicomponent reactions and ionic liquids: a perfect synergy  

E-print Network

of task-specific ionic liquids (ILs), used not only as environmentally benign reaction media, but also Multicomponent reactions and ionic liquids: a perfect synergy for eco-compatible heterocyclic synthesis Nicolas growing interest in the use of room temperature ionic liquids (RTILs).8,9 Furthermore, thanks

Boyer, Edmond

218

Ionic liquid based sodium ion conducting gel polymer electrolytes  

Microsoft Academic Search

A novel thermally and electrochemically stable sodium ion conducting gel polymer electrolyte has been reported, which comprises a solution of NaCF3SO3 (sodium triflate or NaTf) in a room temperature ionic liquid 1-ethyl 3-methyl imidazolium trifluoro-methane sulfonate (EMI-triflate or EMITf) immobilized in poly (vinylidine fluoride-co-hexafluoropropylene) (PVdF-HFP). Different structural, thermal, electrical and electrochemical studies demonstrate promising characteristics of the polymer films, suitable

Deepak Kumar; S. A. Hashmi

2010-01-01

219

1Octanol\\/Water Partition Coefficient of Ionic Liquids  

Microsoft Academic Search

Room temperature ionic liquids are nonvolatile, they can only disperse into the aquatic environment. 1-octanol-water partition coefficient is a measure of the bioconcentration tendency of a chemical in a hydrologic cycle. In this work, 1-octanol-water partition coefficient of 1-ethyl-3-methylimidazolium hexafluoro- phosphate ((emim)(PF6)) and 1-butyl-3-methylimidazolium hexafluorophosphate ((bmim)(PF6)) at 303 K were measured using ultraviolet spectrometer and Karl-Fischer analysis. The 1-octanol\\/water partition

Cheng-Huang Choua; Fu-Shan Perng; David Shan; Hill Wong; Wen Cheng Su

220

Influence of Ionic Liquids in Quasi-Solid State Electrolyte on Dye-Sensitized Solar Cell Performance  

Microsoft Academic Search

Room temperature ionic liquids have been used as electrolytes to investigate the performance and the characteristics in dye-sensitized solar cells (DSSCs). We focused on quasi-solid state electrolyte using ionic liquids, which are non-volatile liquids having relatively high conductivities. We studied the performance of the DSSC device with different anion or cation structures of ionic liquids. The power conversion efficiency of

Hyun-Jeong Lee; Jin-Kook Lee; Mi-Ra Kim; Won Suk Shin; Sung-Ho Jin; Kyong-Hoon Kim; Dae-Won Park; Sang-Wook Park

2006-01-01

221

Properties of ionic liquid solvents for catalysis  

Microsoft Academic Search

Ionic liquids are good solvents for catalytic reactions. The rational selection of the appropriate ionic liquid solvent for a particular reaction requires general knowledge of the properties of ionic liquids, and the details of some properties of the specific ionic liquid solvents being considered. The solvent properties of ionic liquids that are relevant to catalysis are discussed, and sources of

John S Wilkes

2004-01-01

222

Carboxyl-functionalized task-specific ionic liquids for solubilizing metal oxides.  

PubMed

Imidazolium, pyridinium, pyrrolidinium, piperidinium, morpholinium, and quaternary ammonium bis(trifluoromethylsulfonyl)imide salts were functionalized with a carboxyl group. These ionic liquids are useful for the selective dissolution of metal oxides and hydroxides. Although these hydrophobic ionic liquids are immiscible with water at room temperature, several of them form a single phase with water at elevated temperatures. Phase separation occurs upon cooling. This thermomorphic behavior has been investigated by (1)H NMR, and it was found that it can be attributed to the temperature-dependent hydration and hydrogen-bond formation of the ionic liquid components. The crystal structures of four ionic liquids and five metal complexes have been determined. PMID:18841931

Nockemann, Peter; Thijs, Ben; Parac-Vogt, Tatjana N; Van Hecke, Kristof; Van Meervelt, Luc; Tinant, Bernard; Hartenbach, Ingo; Schleid, Thomas; Ngan, Vu Thi; Nguyen, Minh Tho; Binnemans, Koen

2008-11-01

223

Low-melting mixtures based on choline ionic liquids.  

PubMed

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

2014-11-01

224

Liquid-liquid extraction of neodymium(III) by dialkylphosphate ionic liquids from acidic medium: the importance of the ionic liquid cation.  

PubMed

The ionic liquids 1-hexyl-3-methylimidazolium bis(2-ethylhexyl)phosphate, [C6mim][DEHP], 1-hexyl-1-methylpyrrolidinium bis(2-ethylhexyl)phosphate, [C6mpyr][DEHP], and tetrabutylammonium bis(2-ethylhexyl)phosphate, [N4444][DEHP], were prepared and characterized using (1)H and (13)C NMR spectroscopy. The extraction behavior of neodymium(iii) from nitrate medium by these ionic liquids, diluted with the room temperature ionic liquids 1-hexyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide, [C6mim][NTf2], 1-hexyl-3-methylpyrrolidinium bis(trifluoromethylsulfonyl)imide, [C6mpyr][NTf2], and tributylmethylammonium bis(trifluoromethylsulfonyl)imide, [N1444][NTf2], was studied. The distribution ratio of neodymium(iii) was measured as a function of various parameters, such as pH, concentration of the ionic liquid extractant, nature of diluents, concentration of ionic liquid cations and nitrate anions in the aqueous phase. The extraction behavior was compared with that obtained for a solution of the molecular extractant bis(2-ethylhexyl)phosphoric acid (DEHPA) in an ionic liquid diluent. The extraction of neodymium(iii) in the ionic liquids [C6mim][DEHP] and [C6mpyr][DEHP] showed markedly different extraction properties in comparison with that of the quaternary ammonium analogue [N4444][DEHP], especially concerning the pH dependence of the extraction process. These results show that the extraction process can be tuned by the selection of the ionic liquid cation. The extraction experiments also included the trivalent rare-earth ions lanthanum(iii), cerium(iii), praseodymium(iii), ytterbium(iii) and yttrium(iii). Studies of the stripping behavior and the reusability of the ionic liquids were carried out, which indicate that the ionic liquids can be reused with no loss in activity. PMID:23949284

Rout, Alok; Kotlarska, Justyna; Dehaen, Wim; Binnemans, Koen

2013-10-21

225

Synthesis and properties of chiral ammonium-based ionic liquids.  

PubMed

New chiral ammonium-based ionic liquids containing the (1R,2S,5R)-(-)-menthyl group can be easily and efficiently prepared under ambient conditions. The preparation and characterization of trialkyl[(1R,2S,5R)-(-)-menthoxymethyl]ammonium salts is reported. The salts have been demonstrated to be air- and moisture-stable under ambient conditions and can be readily used in a variety of standard experimental procedures. The single-crystal X-ray structure of butyldimethyl[(1R,2S,5R)-(-)-menthoxymethyl]ammonium chloride has been determined. The chiral, room-temperature ionic liquids have been characterized by physical properties such as specific rotation, density, viscosity, thermal degradation, and glass transition temperature. Trialkyl[(1R,2S,5R)-(-)-menthoxymethyl]ammonium chloride prototype ionic liquids have also been found to exhibit strong antimicrobial and high antielectrostatic activities. PMID:15883984

Pernak, Juliusz; Feder-Kubis, Joanna

2005-07-18

226

Synthesis and characterization of new class of ionic liquids containing phenolate anion  

NASA Astrophysics Data System (ADS)

In these manuscript novel ionic liquids containing a new class of "phenolate" anions was synthesized and characterized. 1-methylmidazole with different alkyl chains such as butyl, hexyl and octyl groups was used as the cationic part. All the ionic liquids were obtained as liquids at room temperature. The synthesized ionic liquids were characterized using 1H NMR and 13C NMR spectroscopy. The thermal stability of the ionic liquids was studied using thermo gravimetric analysis (TGA). The effect of temperature on the density and viscosity of the ionic liquids were studied over a temperature range from 293.15 K to 373.15K at atmospheric pressure. From the experimental values of density, the molecular volume, standard molar entropy and the lattice energy of the ionic liquids were calculated.

Lethesh, Kallidanthiyil Chellappan; Wilfred, Cecilia Devi; Taha, M. F.; Thanabalan, M.

2014-10-01

227

Synthesis and characterization of new class of ionic liquids containing phenolate anion  

SciTech Connect

In these manuscript novel ionic liquids containing a new class of 'phenolate' anions was synthesized and characterized. 1-methylmidazole with different alkyl chains such as butyl, hexyl and octyl groups was used as the cationic part. All the ionic liquids were obtained as liquids at room temperature. The synthesized ionic liquids were characterized using {sup 1}H NMR and {sup 13}C NMR spectroscopy. The thermal stability of the ionic liquids was studied using thermo gravimetric analysis (TGA). The effect of temperature on the density and viscosity of the ionic liquids were studied over a temperature range from 293.15 K to 373.15K at atmospheric pressure. From the experimental values of density, the molecular volume, standard molar entropy and the lattice energy of the ionic liquids were calculated.

Lethesh, Kallidanthiyil Chellappan, E-mail: lethesh.chellappan@petronas.com.my [PETRONAS Ionic Liquids Center, Universiti Teknologi PETRONAS (Malaysia); Wilfred, Cecilia Devi; Taha, M. F. [Department of Chemical Engineering, Universiti Teknologi PETRONAS (Malaysia); Thanabalan, M. [Fundamental and Applied Sciences, Universiti Teknologi PETRONAS (Malaysia)

2014-10-24

228

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

2009-01-01

229

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

2005-01-01

230

Task-specific ionic liquid trioctylmethylammonium salicylate as extraction solvent for transition metal ions  

Microsoft Academic Search

A quaternary ammonium-based room temperature ionic liquid trioctylmethylammonium salicylate (TOMAS) has been studied as an extractant of transition metal ions (Fe3+, Cu2+, Ni2+, Mn2+) in aqueous solutions. The effect of pH value on the recovery of metal ions has been investigated. The mechanism of extraction into the ionic liquid has been proposed. The possibility of stripping voltammetric determination of transition

Vladimir M. Egorov; Dmitry I. Djigailo; Dmitry S. Momotenko; Denis V. Chernyshov; Irina I. Torocheshnikova; Svetlana V. Smirnova; Igor V. Pletnev

2010-01-01

231

Dialkylimidazolium ionic liquids as electrolytes for hydrogen production from water electrolysis  

Microsoft Academic Search

Imidazolium ionic liquids (ILs) such as BMI·BF4 and BMI·PF6 were studied by cyclic voltammetry (CV). BMI·BF4 was used as an electrolyte for hydrogen production through water electrolysis. The system using this ionic liquid in a conventional electrochemical cell with platinum electrodes at room temperature and atmospheric pressure gives current densities (j) higher than 20mAcm?2 and efficiencies of more than 94.5%.

Roberto F. de Souza; Janine C. Padilha; Reinaldo S. Gonçalves; Joëlle Rault-Berthelot

2006-01-01

232

Electrokinetic Transport in Ionic Liquids  

E-print Network

A key difficulty in understanding electrokinetic transport in ionic liquids lies in the construction of an appropriate reference dynamics. The common assumption of modelling ion dynamics as a Langevin process is not warranted for solvent-free ionic liquids. The electrokinetic transport of ionic liquids obtained by coarse graining a simple exclusion process defined on a lattice is considered. The resulting dynamical equations can be written as a gradient flow with a degenerate mobility function. This form of the mobility function gives rise to charging behaviours that are different to the ones known in electrolytic solutions; the predicted behaviours agree qualitatively with the phenomenology observed in simulations.

Lee, Alpha A; Goriely, Alain

2015-01-01

233

Electrokinetic Transport in Ionic Liquids  

E-print Network

A key difficulty in understanding electrokinetic transport in ionic liquids lies in the construction of an appropriate reference dynamics. The common assumption of modelling ion dynamics as a Langevin process is not warranted for solvent-free ionic liquids. The electrokinetic transport of ionic liquids obtained by coarse graining a simple exclusion process defined on a lattice is considered. The resulting dynamical equations can be written as a gradient flow with a degenerate mobility function. This form of the mobility function gives rise to charging behaviours that are different to the ones known in electrolytic solutions; the predicted behaviours agree qualitatively with the phenomenology observed in simulations.

Alpha A. Lee; Dominic Vella; Alain Goriely

2015-02-13

234

Ionic Liquid Epoxy Resin Monomers  

NASA Technical Reports Server (NTRS)

Ionic liquid epoxide monomers capable of reacting with cross-linking agents to form polymers with high tensile and adhesive strengths. Ionic liquid epoxide monomers comprising at least one bis(glycidyl) N-substituted nitrogen heterocyclic cation are made from nitrogen heterocycles corresponding to the bis(glycidyl) N-substituted nitrogen heterocyclic cations by a method involving a non-nucleophilic anion, an alkali metal cation, epichlorohydrin, and a strong base.

Paley, Mark S. (Inventor)

2013-01-01

235

Brønsted Acidic Ionic Liquids: Fast, Mild, and Efficient Catalysts for Solvent?Free Tetrahydropyranylation of Alcohols  

Microsoft Academic Search

Brønsted acidic ionic liquids as efficient and reusable catalysts for the protection of alcohols as tetrahydropyranyl (THP) ethers under solvent?free conditions at room temperature was investigated. Good to excellent yields were obtained at a faster rate over [BMIm][HSO4] or [BMIm][H2PO4].

Zhiying Duan; Yanlong Gu; Youquan Deng

2005-01-01

236

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

2000-01-01

237

Efficient esterification of carboxylic acids and phosphonic acids with trialkyl orthoacetate in ionic liquid  

Microsoft Academic Search

An operationally simple, inexpensive, efficient, and environmentally friendly esterification of various carboxylic acids, phosphonic acids, and phosphinic acids with triethyl orthoacetate or trimethyl orthoacetate under neutral conditions in a typical room temperature ionic liquid, 1-butyl-3-methylimidazolium hexafluorophosphate, was successfully carried out to provide the corresponding ethyl esters or methyl esters in high yields.

Tomonori Yoshino; Satomi Imori; Hideo Togo

2006-01-01

238

Novel bipyridinium ionic liquids as liquid electrochromic devices.  

PubMed

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

2014-04-01

239

Room temperature superconductors  

Microsoft Academic Search

If the Holy Grail of room temperature superconductivity could be achieved, the impact on could be enormous. However, a useful room temperature superconductor for most applications must possess a {Tc} somewhat above room temperature and must be capable of sustaining superconductivity in the presence of magnetic fields while carrying a significant current load. The authors will return to the subject

Arthur W. Sleight

1995-01-01

240

Room-Temperature Superconductivity  

Microsoft Academic Search

This is the first book on the subject of room-temperature superconductivity. The main purpose of the book is twofold. First, to show that, under suitable conditions, superconductivity can occur above room temperature. Secondly, to present general guidelines on how to synthesize a room temperature superconductor. The book begins with an introduction into the physics of the superconducting state and superconducting

A. Mourachkine

2006-01-01

241

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.

2008-07-12

242

Importance of glassy fragility for energy applications of ionic liquids  

E-print Network

Ionic liquids (ILs) are salts that are liquid close to room temperature. Their possible applications are numerous, e.g., as solvents for green chemistry in various electrochemical devices, and even for such "exotic" purposes as spinning-liquid mirrors for lunar telescopes. Here we concentrate on their use for new advancements in energy-storage and -conversion devices: Batteries, supercapacitors or fuel cells using ILs as electrolytes could be important building blocks for the sustainable energy supply of tomorrow. Interestingly, ILs show glassy freezing and the universal, but until now only poorly understood dynamic properties of glassy matter, dominate many of their physical properties. We show that the conductivity of ILs, an essential figure of merit for any electrochemical application, depends in a systematic way not only on their glass temperature but also on the so-called fragility, characterizing the non-canonical super-Arrhenius temperature dependence of their ionic mobility.

P. Sippel; P. Lunkenheimer; S. Krohns; E. Thoms; A. Loidl

2015-02-24

243

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.

2007-06-25

244

Applications of Ionic Liquid Technologies to Nuclear Separations  

SciTech Connect

Room temperature Ionic Liquids (ILs), organic salts that are liquid at, or close to room temperature have great potential application for uses in liquid-liquid separations processes. As a class of liquids, ILs typically have wide liquid ranges, are non-volatile, and have solvent characteristics (hydro- and lipophilicity, hydrogen-bond donor and acceptor ability etc) that can be controlled and modified by suitable changes to either the cation or anionic components of the IL. We have begun the exploration of actinide separations using a variety of technologies based upon the use of ILs including, liquid/liquid extraction using traditional extractants; incorporating an extractant functionality into an IL; immobilizing IL extractant phases on solid supports; and utilization of the solubilizing power of ILs to prepare cellulose-based materials for f-element separations. ILs can thus be considered as a new class of materials for nuclear separations, distinct from molecular solvents a nd from high temperature molten salts, with adjustable solvent characteristics, unique properties, and the potential for enhancing the principles of ''green'' chemistry in various chemical processes.

Rogers, Robin D.; Holbrey, John D.; Spear, Scott K.; Gutowski, Keith E.; Bridges, Nicholas J.; Cocalia, Violina A.; Swatloski, Richard P.

2003-09-10

245

Efficient and green synthesis of tetrasubstituted pyrroles promoted by task-specific basic ionic liquids as catalyst in aqueous media.  

PubMed

Synthesis of tetrasubstituted pyrroles by the three-component condensation reaction of acid chlorides, dialkyl acetylenedicarboxylates, and amino acids in the presence of various room-temperature ionic liquids (RTILs) as catalysts in water is reported. Among the ionic liquids used, the basic functionalized ionic liquid, butyl methyl imidazolium hydroxide [bmim]OH, was the most effective catalyst. The influence of reaction temperature, reaction time, and amount of ionic liquid on the reaction was investigated. The [bmim]OH/H(2)O catalyst system could be reused for at least five recycles without appreciable loss of efficiency. PMID:19381850

Yavari, Issa; Kowsari, Elaheh

2009-11-01

246

Synthesis and anti-microbial activity of hydroxylammonium ionic liquids.  

PubMed

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

2011-06-01

247

Additive-containing ionic liquid electrolytes for secondary lithium battery  

Microsoft Academic Search

Room temperature ionic liquid (RTIL) consisting of N-methyl-N-propylpiperidinium (PP13) cation and bis(trifluoromethanesulfonyl)imide (TFSI) anion was synthesized and its electrochemical stability was investigated in comparison with 1-butyl-3-methylimidazolium tetrafluoroborate (BMIBF4) and 1-butyl-3-methylimidazolium hexafluorophosphate (BMIPF6). The electrochemical window of PP13-TFSI (5.8V versus Li\\/Li+) is wider than that of BMIBF4 (4.7V) and BMIPF6 (4.5V). The cathodic limit of the PP13-TFSI is about ?0.3V versus

Jinqiang Xu; Jun Yang; Yanna NuLi; Jiulin Wang; Zongshuang Zhang

2006-01-01

248

Application of Headspace Liquid-Phase Microextraction Using Ionic Liquid as Extractant Combined with Gas Chromatography-Hydrogen Flame Ionization Detector to the Determination of BTEXs in Water  

Microsoft Academic Search

This paper presents a new headspace-liquid-phase microextraction (HS-LPME) strategy for extraction and preconcentration of benzene, toluene, ethyl- benzene, and o-, m- and p-xylenes (BTEXs) from aqueous samples. A typical room temperature ionic liquid, 1-butyl-3-methylimidazolium hexafluorophosphate ([BMIM]PF6), was used as extractant, and the extract was subsequently determined by gas chromatography-hydrogen flame ionization detection (GC-FID). Parameters such as ionic liquid volume, sampling

Minghua Huang; Xiaoguo Ma

2009-01-01

249

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

2009-08-01

250

Solubility and aggregation of charged surfactants in ionic liquids.  

PubMed

Room-temperature ionic liquids (ILs) exhibit a unique set of properties, leading to opportunities for numerous applications. To obtain a better understanding of IL interfaces at a molecular level, we combined charged surfactants with ILs and studied their interfacial behavior. The critical micelle concentration (cmc) of each surfactant-IL pair was determined from both solubility phase diagrams and isotherms. Because the cmc is equivalent to the solubility at the Krafft temperature, a connection between the solubility of the surfactant and the physical properties of the underlying ionic liquid was established. Interfacial energy was found to be the major factor affecting the surfactant aggregation process, although its magnitude depends strongly on the IL structure. The results here give insight into explaining the nature of self-assembly of surfactants at IL interfaces and the interaction between solutes and IL solvents. PMID:22168452

Chen, Lang G; Bermudez, Harry

2012-01-17

251

Synthesis and characterization of 5-cyanotetrazolide-based ionic liquids.  

PubMed

New salts based on imidazolium, pyrrolidinium, phosphonium, guanidinium, and ammonium cations together with the 5-cyanotetrazolide anion [C2 N5 ](-) are reported. Depending on the nature of cation-anion interactions, characterized by XRD, the ionic liquids (ILs) have a low viscosity and are liquid at room temperature or have higher melting temperatures. Thermogravimetric analysis, cyclic voltammetry, viscosimetry, and impedance spectroscopy display a thermal stability up to 230?°C, an electrochemical window of 4.5?V, a viscosity of 25?mPa?s at 20?°C, and an ionic conductivity of 5.4 mS cm(-1) at 20?°C for the IL 1-butyl-1-methylpyrrolidinium 5-cyanotetrazolide [BMPyr][C2 N5 ]. On the basis of these results, the synthesized compounds are promising electrolytes for lithium-ion batteries. PMID:25504790

Bergholz, Timm; Oelkers, Benjamin; Huber, Benedikt; Roling, Bernhard; Sundermeyer, Jörg

2015-02-01

252

Hydrogen bonding in ionic liquids.  

PubMed

Ionic liquids (IL) and hydrogen bonding (H-bonding) are two diverse fields for which there is a developing recognition of significant overlap. Doubly ionic H-bonds occur when a H-bond forms between a cation and anion, and are a key feature of ILs. Doubly ionic H-bonds represent a wide area of H-bonding which has yet to be fully recognised, characterised or explored. H-bonds in ILs (both protic and aprotic) are bifurcated and chelating, and unlike many molecular liquids a significant variety of distinct H-bonds are formed between different types and numbers of donor and acceptor sites within a given IL. Traditional more neutral H-bonds can also be formed in functionalised ILs, adding a further level of complexity. Ab initio computed parameters; association energies, partial charges, density descriptors as encompassed by the QTAIM methodology (?BCP), qualitative molecular orbital theory and NBO analysis provide established and robust mechanisms for understanding and interpreting traditional neutral and ionic H-bonds. In this review the applicability and extension of these parameters to describe and quantify the doubly ionic H-bond has been explored. Estimating the H-bonding energy is difficult because at a fundamental level the H-bond and ionic interaction are coupled. The NBO and QTAIM methodologies, unlike the total energy, are local descriptors and therefore can be used to directly compare neutral, ionic and doubly ionic H-bonds. The charged nature of the ions influences the ionic characteristics of the H-bond and vice versa, in addition the close association of the ions leads to enhanced orbital overlap and covalent contributions. The charge on the ions raises the energy of the Ylp and lowers the energy of the X-H ?* NBOs resulting in greater charge transfer, strengthening the H-bond. Using this range of parameters and comparing doubly ionic H-bonds to more traditional neutral and ionic H-bonds it is clear that doubly ionic H-bonds cover the full range of weak through to very strong H-bonds. PMID:25582457

Hunt, Patricia A; Ashworth, Claire R; Matthews, Richard P

2015-02-23

253

Solvent-free aza-Markovnikov and aza-Michael additions promoted by a catalytic amount of imidazolide basic ionic liquids  

Microsoft Academic Search

A family of imidazolide ionic liquids were synthesized and characterized. These ionic liquids combined the virtues of strong basicity and relatively good thermal stability. Catalytic properties of these imidazolide ionic liquids were investigated and satisfactory yield was achieved when 2.0mol% of [Bmim]Im was used as catalyst for aza-Markovnikov addition under solvent-free condition at room temperature in one hour. Experimental results

Xuewei Chen; Xuehui Li; Hongbing Song; Yu Qian; Furong Wang

2011-01-01

254

Synthesis of new solid polymer electrolyte and actuator based on PEDOT/NBR/ionic liquid  

NASA Astrophysics Data System (ADS)

The conducting polymer actuator was presented. The solid polymer electrolyte based on nitrile rubber (NBR) activated with different ionic liquids was prepared. The three different grades of NBR films were synthesized by emulsion polymerization with different amount of acrylonitrile, 23, 35, and 40 mol. %, respectively. The effect of acrylonitrile content on the ionic conductivity and dielectric constant of solid polymer electrolytes was characterized. A conducting polymer, poly(3,4-ethylenedioxythiophene) (PEDOT), was synthesized on the surface of the NBR layer by using a chemical oxidation polymerization technique, and room temperature ionic liquids (RTIL) based on imidazolium salts, e.g. 1-butyl-3-methyl imidazolium X [where X= BF 4 -, PF 6 -, (CF 3SO II) IIN -], were absorbed into the composite film. The effects of the anion size of the ionic liquids on the displacement of the actuator were examined. The displacement increased with increasing the anion-size of the ionic liquids.

Cho, M. S.; Seo, H. J.; Nam, J. D.; Choi, H. R.; Koo, J. C.; Lee, Y.

2006-03-01

255

Room-Temperature-Cured Copolymers for Lithium Battery Gel Electrolytes  

NASA Technical Reports Server (NTRS)

Polyimide-PEO copolymers (PEO signifies polyethylene oxide) that have branched rod-coil molecular structures and that can be cured into film form at room temperature have been invented for use as gel electrolytes for lithium-ion electric-power cells. These copolymers offer an alternative to previously patented branched rod-coil polyimides that have been considered for use as polymer electrolytes and that must be cured at a temperature of 200 C. In order to obtain sufficient conductivity for lithium ions in practical applications at and below room temperature, it is necessary to imbibe such a polymer with a suitable carbonate solvent or ionic liquid, but the high-temperature cure makes it impossible to incorporate and retain such a liquid within the polymer molecular framework. By eliminating the high-temperature cure, the present invention makes it possible to incorporate the required liquid.

Meador, Mary Ann B.; Tigelaar, Dean M.

2009-01-01

256

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

2009-01-01

257

The distillation and volatility of ionic liquids  

Microsoft Academic Search

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

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

2006-01-01

258

Ionic liquids: Green solvents for nonaqueous biocatalysis  

Microsoft Academic Search

Ionic liquids hold potential as green solvents because of their lack of vapour pressure, and are opening up a burgeoningly new field of nonaqueous enzymology. As compared to those observed in conventional organic solvents, enzymes in ionic liquids have presented enhanced activity, stability, and selectivity. Advantages of using ionic liquids over the use of normal organic solvents as reaction medium

Zhen Yang; Wubin Pan

2005-01-01

259

Towards Molecular Dynamics Simulations of Chiral Room-Temperature Ionic Liquids  

E-print Network

of [bmim][Br] which differ in the position of the binding site of the bromine anion. According to the ChelpG charges, the C16-C19 bond is strongly polarized if the bromine anion binds above the imidazolium ring while being non-polar when the bromine anion is coplanar with the imidazolium ring; see Fig. 2 of main

Lisal, Martin

260

Room-Temperature Ionic Liquids and Protective Phospholipid Membranes: Interactions on Surfaces  

Technology Transfer Automated Retrieval System (TEKTRAN)

Green chemistry is a growing area of research that involves reducing or eliminating hazardous materials (products and solvents) from chemical processes. An area of green chemistry that is quite interesting to us is bioelectrocatalytic transformation of lipids in non-aqueous solvents called room-tem...

261

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

2007-09-01

262

Application of Ionic Liquids in Liquid Chromatography  

Microsoft Academic Search

Interest in ionic liquids (ILs) for their potential application in analytical chemistry continues to grow. Their usefulness can be due to favourable physicochemical properties, like the lack of vapour pressure, good thermal and chemical stability as well as very good dissolution properties regarding both organic and inorganic compounds. A specific feature of ILs is that these compounds provide strong proton

Micha? Piotr Marsza??; Roman Kaliszan

2007-01-01

263

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.

2013-03-01

264

Ionic Liquids in Biomass Processing  

Microsoft Academic Search

\\u000a Ionic liquids have been studied for their special solvent properties in a wide range of processes, including reactions involving\\u000a carbohydrates such as cellulose and glucose. Biomass is a widely available and renewable resource that is likely to become\\u000a an economically viable source of starting materials for chemical and fuel production, especially with the price of petroleum\\u000a set to increase as

Suzie Tan; Douglas MacFarlane

265

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

2014-01-01

266

Application of ionic liquids in hydrometallurgy.  

PubMed

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

2014-01-01

267

[Cu(I)(bpp)]BF4: the first extended coordination network prepared solvothermally in an ionic liquid solvent  

E-print Network

a solvothermal route. In the past few years, room temperature ionic liquids (RTILs), especially those based dimensional framework via weak inter-chain interactions of copper pairs. The Cu(I)­Cu(I) weak interactions is the only structure found similar to 1, which was prepared by slow diffusion using silver per- chlorate

Li, Jing

268

Regioselective Iodination of Arenes Using Iodine\\/NaBO3 · 4H2O System in Ionic Liquid  

Microsoft Academic Search

A mild, efficient, and simple protocol was developed for iodination of arenes and heterocyclic compounds with molecular iodine catalyzed by sodium perborate in ionic liquid. The methodology offered iodoarenes in good to excellent yields at room temperature. The protocol proved to be highly selective, as a single isomer was formed exclusively in most of the substrates.

Sachin V. Bhilare; Amol R. Deorukhkar; Nitin B. Darvatkar; Manikrao M. Salunkhe

2008-01-01

269

COMPARISON OF PEROXIDASE ACTIVITIES OF HEMIN, CYTOCHROME C AND MICROPEROXIDASE-11 IN MOLECULAR SOLVENTS AND IMIDAZOLIUM-BASED IONIC LIQUIDS  

Technology Transfer Automated Retrieval System (TEKTRAN)

The ability of ferriprotoporphyrin(IX) chloride (hemin), microperoxidase-11 (MP-11), and cytochrome c (cyt-c) to oxidize guaiacol (2-methoxyphenol) was examined in the room-temperature ionic liquids (IL) 1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide and the hexafluorophosphates of 1-...

270

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.

2014-06-01

271

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.

2010-12-01

272

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

2005-01-01

273

Experimental investigations of an ionic-liquid-based, magnesium ion conducting, polymer gel electrolyte  

Microsoft Academic Search

Studies on a novel magnesium ion conducting gel polymer electrolyte based on a room temperature ionic liquid (RTIL) is reported. It comprises a Mg-salt, Mg(CF3SO3)2 [or magnesium triflate, Mg(Tf)2] solution in an ionic liquid, 1-ethyl-3-methylimidazolium trifluoro-methanesulfonate (EMITf), immobilized with poly(vinylidene fluoride-hexafluoropropylene) (PVdF-HFP), which is a freestanding, semitransparent and flexible film with excellent mechanical strength. Physical and electrochemical analyses demonstrate promising

G. P. Pandey; S. A. Hashmi

2009-01-01

274

Lithium insertion in graphite from ternary ionic liquid-lithium salt electrolytes  

Microsoft Academic Search

In this paper we report the results of chemical-physical investigation performed on ternary room temperature ionic liquid–lithium salt mixtures as electrolytes for lithium-ion battery systems. The ternary electrolytes were made by mixing N-methyl-N-propyl pyrrolidinium bis(fluorosulfonyl) imide (PYR13FSI) and N-butyl-N-methylpyrrolidinium bis(trifluoromethanesulfonyl) imide (PYR14TFSI) ionic liquids with lithium hexafluorophosphate (LiPF6) or lithium bis(trifluoromethanesulfonyl)imide (LiTFSI). The mixtures were developed based on preliminary results

Giovanni B. Appetecchi; Maria Montanino; Andrea Balducci; Simon F. Lux; Martin Winterb; Stefano Passerini

2009-01-01

275

Electrochemical behavior of copper current collector in imidazolium-based ionic liquid electrolytes  

Microsoft Academic Search

The electrochemical behaviors of copper current collector in 1-alkyl-3-methylimidazolium bis[(trifluoromethyl)sulfonyl] imide\\u000a ionic liquid electrolytes were investigated and compared with that in ethylene carbonate\\/dimethyl carbonate solutions. Cyclic\\u000a voltammetry results showed that large oxidation–reduction current of the copper foil appeared in ethylene carbonate\\/dimethyl\\u000a carbonate solutions, while a much smaller current in the room temperature ionic liquid electrolytes decreased gradually, indicating\\u000a that the

Chengxin Peng; Li Yang; Shaohua Fang; Jixian Wang; Zhengxi Zhang; Kazuhiro Tachibana; Yong Yang; Shiyong Zhao

2010-01-01

276

Ionic liquid enabled FeS2 for high-energy-density lithium-ion batteries.  

PubMed

High-energy-density FeS2 cathodes en-abled by a bis(trifluoromethanesulfonyl)imide (TFSI-) anion-based room temperature ionic liquid (RTIL) electrolyte are demonstrated. A TFSI-based ionic liquid (IL) significantly mitigates polysulfide dissolution, and therefore the parasitic redox shuttle mechanism, that plagues sulfur-based electrode chemistries. FeS2 stabilization with a TFSI(-) -based IL results in one of the highest energy density cathodes, 542 W h kg(-1) (normalized to cathode composite mass), reported to date. PMID:25236752

Evans, Tyler; Piper, Daniela Molina; Kim, Seul Cham; Han, Sang Sub; Bhat, Vinay; Oh, Kyu Hwan; Lee, Se-Hee

2014-11-19

277

A new class of room temperature molten salts for battery applications  

NASA Astrophysics Data System (ADS)

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 the class shows that the material is liquid below room temperature over its entire composition range. A proof of concept battery cell using the new electrolyte was demonstrated. Electrochemical tests show that battery anodes and cathodes will operate in the new electrolytes. By varying the ratio of the components of the new melts, the chemical and physical properties can be changed over a very wide range.

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

1981-10-01

278

Unexpected decomposition of the bis (trifluoromethylsulfonyl) amide anion during electrochemical copper oxidation in an ionic liquid  

Microsoft Academic Search

In this letter we report on the decomposition of the bis (trifluoromethylsulfonyl) amide (TFSA) anion under quite mild electrochemical conditions. The results show clearly that the TFSA anion can easily be decomposed during anodic oxidation of copper in the ionic liquid 1-butyl-1-methylpyrrolidinium bis (trifluoromethylsulfonyl) amide [BMP] TFSA at 70°C leading to the formation of CuF2. At room temperature, however, no

A. S. Ismail; S. Zein El Abedin; O. Höfft; F. Endres

2010-01-01

279

Molecular dynamics simulation of imidazolium-based ionic liquids. I. Dynamics and diffusion coefficient  

Microsoft Academic Search

Molecular dynamics simulations are used to study the dynamics and transport properties of 12 room-temperature ionic liquids of the 1-alkyl-3-methylimidazolium [amim]+ (alkyl=methyl, ethyl, propyl, and butyl) family with PF6-, NO3-, and Cl- counterions. The explicit atom transferable force field of Canongia Lopes et al. [J. Phys. Chem. B 108, 2038 (2004)] is used in the simulations. In this first part,

M. H. Kowsari; Saman Alavi; Mahmud Ashrafizaadeh; Bijan Najafi

2008-01-01

280

Molybdenum electrodes for hydrogen production by water electrolysis using ionic liquid electrolytes  

Microsoft Academic Search

The hydrogen production by water electrolysis was tested with different electrocatalysts (molybdenum, nickel, iron alloys containing chromium, manganese and nickel) using aqueous solutions of ionic liquid (IL) like 1-butyl-3-methylimidazolium tetrafluoroborate (BMI.BF4). The hydrogen evolution reaction (HER) was performed at room temperature in a potential of ?1.7V (PtQRE). A Hoffman cell apparatus was used to water electrolysis with current density values,

Roberto F. de Souza; Gabriel Loget; Janine C. Padilha; Emilse M. A. Martini; Michele O. de Souza

2008-01-01

281

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

2007-01-01

282

A roadmap to uranium ionic liquids: anti-crystal engineering.  

PubMed

In the search for uranium-based ionic liquids, tris(N,N-dialkyldithiocarbamato)uranylates have been synthesized as salts of the 1-butyl-3-methylimidazolium (C4mim) cation. As dithiocarbamate ligands binding to the UO2(2+) unit, tetra-, penta-, hexa-, and heptamethylenedithiocarbamates, N,N-diethyldithiocarbamate, N-methyl-N-propyldithiocarbamate, N-ethyl-N-propyldithiocarbamate, and N-methyl-N-butyldithiocarbamate have been explored. X-ray single-crystal diffraction allowed unambiguous structural characterization of all compounds except N-methyl-N-butyldithiocarbamate, which is obtained as a glassy material only. In addition, powder X-ray diffraction as well as vibrational and UV/Vis spectroscopy, supported by computational methods, were used to characterize the products. Differential scanning calorimetry was employed to investigate the phase-transition behavior depending on the N,N-dialkyldithiocarbamato ligand with the aim to establish structure-property relationships regarding the ionic liquid formation capability. Compounds with the least symmetric N,N-dialkyldithiocarbamato ligand and hence the least symmetric anions, tris(N-methyl-N-propyldithiocarbamato)uranylate, tris(N-ethyl-N-propyldithiocarbamato)uranylate, and tris(N-methyl-N-butyldithiocarbamato)uranylate, lead to the formation of (room-temperature) ionic liquids, which confirms that low-symmetry ions are indeed suitable to suppress crystallization. These materials combine low melting points, stable complex formation, and hydrophobicity and are therefore excellent candidates for nuclear fuel purification and recovery. PMID:24737451

Yaprak, Damla; Spielberg, Eike T; Bäcker, Tobias; Richter, Mark; Mallick, Bert; Klein, Axel; Mudring, Anja-Verena

2014-05-19

283

Ionic liquids for rechargeable lithium batteries  

Microsoft Academic Search

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, BMIMBF, and BMIMTf. Thermal stabilities were measured for neat ionic liquids and for BMIMBF-LiBF, BMIMTf-LiTf, BMIMTFSI-LiTFSI mixtures. Conductivities have been measured

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

2005-01-01

284

Dissolution of Wood in Ionic Liquids  

Microsoft Academic Search

The present paper demonstrates that both hardwoods and softwoods are readily soluble in various imidazolium-based ionic liquids (ILs) under gentle conditions. More specifically, a variety of ionic liquids can only partially dissolve wood chips, whereas ionic liquids such as 1-butyl-3-methylimida- zolium chloride and 1-allyl-3-methylimidazolium chloride have good solvating power for Norway spruce sawdust and Norway spruce and Southern pine thermomechanical

Ilkka Kilpeläinen; Haibo Xie; Alistair King; Mari Granstrom; Sami Heikkinen; Dimitris S. Argyropoulos

2007-01-01

285

Early Events in Ionic Liquid Radiation Chemistry  

SciTech Connect

Ionic liquids are interesting and useful materials whose solvation time scales are up to thousands of times longer than in conventional solvents. The extended lifetimes of pre-solvated electrons and other energetic species in ionic liquids has profound consequences for the radiolytic product distributions and reactivity patterns. We use a newly developed, multiplexed variation of pulse-probe spectroscopy to measure the kinetics of the early dynamical and reactive events in ionic liquids.

Wishart, J.F.; Cook, A.; Rimmer, R.D.; Gohdo, M.

2010-09-14

286

A binary ionic liquid system composed of N-methoxyethyl- N-methylpyrrolidinium bis(trifluoromethanesulfonyl)-imide and lithium bis(trifluoromethanesulfonyl)imide: A new promising electrolyte for lithium batteries  

Microsoft Academic Search

Room temperature ionic liquids are nowadays the most appealing research target in the field of liquid electrolytes for lithium batteries, due to their high thermal stability, ionic conductivity and wide electrochemical windows. The cation structure of such solvents strictly influences their physical and chemical properties, in particular the viscosity and conductivity.In this paper we report on the preparation and characterization

S. Ferrari; E. Quartarone; P. Mustarelli; A. Magistris; S. Protti; S. Lazzaroni; M. Fagnoni; A. Albini

2009-01-01

287

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

PubMed

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

2014-04-01

288

Coherence time of the nuclear spin of ionized phosphorus donors in ^28Si at liquid He and room temperature  

NASA Astrophysics Data System (ADS)

Remarkable coherence times have recently been reported for the nuclear spin of dilute neutral ^31P in highly enriched ^28Si [1]. For ionized ^31P, the removal of the hyperfine-coupled electron should result in a nuclear spin even more decoupled from the environment, and hence even longer coherence times at cryogenic temperatures. The coherence time of ionized ^31P was recently observed in natural Si, and while the nuclear coherence time was indeed much longer than the electron coherence time measured in the same device, it was limited to 18 ms due to both the presence of ^29Si as well as the readout mechanism being employed [2]. Here we report on coherence time measurements for ionized ^31P in the same ^28Si samples used for the previous [1] neutral donor study. In addition to the promise of longer cryogenic coherence times, the removal of the hyperfine-coupled electron should result in a profound change in the temperature dependence of T2. For the neutral donor, the electron T1 decreases very rapidly with increasing temperature, and even at 4.2 K the nuclear T2 is limited by the electron T1 [1]. This mechanism is absent for the ionized donor, and we will report on nuclear coherence time measurements for ionized ^31P at room temperature.[4pt] [1] M. Steger et al., Science 336, 1280 (2012).[0pt] [2] L. Dreher et al., Phys. Rev. Lett. 108, 027602 (2012).

Thewalt, Michael L. W.; Saeedi, Kamyar; Simmons, Stephanie; Morton, John J. L.

2013-03-01

289

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

2013-01-01

290

Protein Structure and Stability in Neat Ionic Liquid  

NASA Astrophysics Data System (ADS)

Ionic liquid (IL) as a medium for room temperature preservation of biomacromolecules has been proposed, and to investigate the possibility, we studied physicochemical and enzymatic properties of several proteins in the neat hydrophilic IL, ethylmethyl imidazolium ethyl sulfate [EMIM][EtSO4]. Molecular dissolution of ?-chymotypsin, cytochrome-c and other proteins could be achieved with moderate heating (60C). Dynamic light scattering and dilute solution viscometry typically reveal protein size slightly larger than in buffer, suggesting different solvation or protein unfolding. Spectroscopic methods (UV-Vis, fluorescence, FTIR, CD) show largely unchanged secondary structure but significantly changed tertiary structure. IL-dissolved cytochrome-c has heightened peroxidase activity, supporting the same conclusions. Transfer of dissolved protein from IL to buffer and ensuing alterations to protein conformation/activity will be discussed.

Bihari, Malvika; Russell, Thomas P.; Hoagland, David A.

2010-03-01

291

New ionic liquids as innovative reaction media  

NASA Astrophysics Data System (ADS)

New ionic liquids were developed based on triazolium salts and guanidinium salts. By introduction of functions, such as organocatalytic units, into these units task-specific ionic liquids could be obtained. These products can be used as efficient catalysts in asymmetric syntheses.

Liebscher, J.; Shah, J.; Yacob, Z.; Sadiq, S.; Hanelt, S.; Blumenthal, H.

2009-08-01

292

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

2008-01-01

293

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.

2013-02-01

294

Chiral discrimination by ionic liquids: impact of ionic solutes.  

PubMed

Chiral ionic liquids hold promise in many asymmetric applications. This study explores the impact of ionic solutes on the chiral discrimination of five amino acid methyl ester-based ionic liquids, including L- and D-alanine methyl ester, L-proline methyl ester, L-leucine methyl ester, and L-valine methyl ester cations combined with bis(trifluoromethanesulfonimide) anion. Circularly polarized luminescence spectroscopy was used to study the chiral discrimination by measuring the racemization equilibrium of a dissymmetric europium complex, Eu(dpa)3 (3-) (where dpa = 2,6-pyridinedicarboxylate). The chiral discrimination measured was dependent on the concentration of Eu(dpa)3 (3-) and this concentration-dependence was different in each of the ionic liquids. Ionic liquids with L-leucine methyl ester and L-valine methyl ester even switched enantiomeric preference based on the solute concentration. Changing the cation of the Eu(dpa)3 (3-) salt from tetrabutylammonium to tetramethylammonium ion also affected the chiral discrimination demonstrated by the ionic liquids. Chirality 27:320-325, 2015. © 2015 Wiley Periodicals, Inc. PMID:25727925

Brown, Christopher J; Hopkins, Todd A

2015-04-01

295

Ionic liquid incorporating thiosalicylate for metal removal  

NASA Astrophysics Data System (ADS)

Ionic liquids are a class of organic molten salts "designer solvents" that are composed totally of anions (inorganic and organic polyatomic) and organic cations. The replacement of volatile organic solvents from a separation process is of utmost importance since the use of a large excess of these solvents is hazardous and creates ecological problem. The new method for metal ion extraction is by using task-specific ionic liquids such as ionic liquids which incorporate thiosalicylate functionality. This paper looks at producing a new cluster of ionic liquids which incorporates thiosalicylate with pyridinium cation. Its thermophysical properties such as density and viscosity in single and binary mixtures are studied. The ionic liquids' capability in metal removal processes is evaluated.

Wilfred, Cecilia Devi; Mustafa, Fadwa Babiker; Romeli, Fatimah Julia

2012-09-01

296

Electrochemical transistors with ionic liquids for enzymatic sensing  

NASA Astrophysics Data System (ADS)

Over the past decade conducting polymer electrodes have played an important role in bio-sensing and actuation. Recent developments in the field of organic electronics have made available a variety of devices that bring unique capabilities at the interface with biology. One example is organic electrochemical transistors (OECTs) that are being developed for a variety of bio-sensing applications, including the detection of ions, and metabolites, such as glucose and lactate. Room temperature ionic liquids (RTILs) are organic salts, which are liquid at ambient temperature. Their nonvolatile character and thermal stability makes them an attractive alternative to conventional organic solvents. Here we report an enzymatic sensor based on an organic electro-chemical transistor with RTIL's as an integral part of its structure and as an immobilization medium for the enzyme and the mediator. Further investigation shows that these platforms can be incorporated into flexible materials such as carbon cloth and can be utilized for bio-sensing. The aim is to incorporate the overall platform in a wearable sensor to improve athlete performance with regards to training. In this manuscript an introduction to ionic liquids (ILs), IL - enzyme mixtures and a combination of these novel materials being used on OECTs are presented.

Fraser, Kevin J.; Yang, Sang Yoon; Cicoira, Fabio; Curto, Vincenzo F.; Byrne, Robert; Benito-Lopez, Fernando; Khodagholy, Dion; Owens, Róisín M.; Malliaras, George G.; Diamond, Dermot

2011-10-01

297

Marcus-like inversion in electron transfer in neat ionic liquid and ionic liquid-mixed micelles.  

PubMed

Ultrafast photoinduced electron transfer (PET) from N,N-dimethylaniline (DMA) to coumarin dyes in a room-temperature ionic liquid (RTIL, [pmim][BF(4)]) and in a mixed micelle containing the RTIL and a triblock copolymer, (PEO)(20)-(PPO)(70)-(PEO)(20), (Pluronic P123) is studied using femtosecond upconversion. A Marcus-like inversion in the rate of PET is observed in neat RTIL. This is attributed to high viscosity and nanostructuring of the RTIL. Diffusion and the rate of PET in the neat RTIL are slower than those in the RTIL-P123 mixed micelle. The coumarin dyes exhibit faster electron transfer and translational diffusion (anisotropy decay) in the RTIL-P123 mixed micelle compared to that in the P123 micelle. PMID:21466177

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

2011-04-28

298

Electrolyte-gated polymer thin film transistors making use of ionic liquids and ionic liquid-solvent mixtures  

NASA Astrophysics Data System (ADS)

Electrolyte-Gated (EG) transistors, making use of electrolytes as the gating medium, are interesting for their low operation voltage. Furthermore, EG polymer transistors offer the advantage of solution processing, low cost, and mechanical flexibility. Despite the intense research activity in EG transistors, clear guidelines to correlate the properties of the materials used for the transistor channel and electrolytes with the doping effectiveness of the transistor channel are yet to be clearly established. Here, we investigate the use of room temperature ionic liquids (RTILs) based on the [TFSI] anion (namely, [EMIM][TFSI], [BMIM][TFSI], and [PYR14][TFSI]), to gate transistors making use of MEH-PPV as the channel material. Morphological studies of MEH-PPV and RTIL films showed a certain degree of segregation between the two components. All the EG transistors featured clear drain-source current modulations at voltages below 1 V. Polar solvent additives as propylene carbonate were used to improve the transistor response time.

Sayago, Jonathan; Meng, Xiang; Quenneville, Francis; Liang, Shuang; Bourbeau, Étienne; Soavi, Francesca; Cicoira, Fabio; Santato, Clara

2015-03-01

299

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)

2007-09-03

300

Actinide chemistry in ionic liquids.  

PubMed

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

2013-04-01

301

Theoretical reconstruction and elementwise analysis of photoelectron spectra for imidazolium-based ionic liquids.  

PubMed

We have recently measured core level and valence band XPS, UPS, and MIES spectra of two room temperature ionic liquids composed of bis(trifluoromethylsulfonyl)imide anions ([Tf(2)N](-)) and either 1-ethyl-3-methyl-imidazolium ([EMIm](+)) or 1-octyl-3-methyl-imidazolium cations ([OMIm](+)). [T. Ikari, A. Keppler, M. Reinmöller, W. J. D. Beenken, S. Krischok, M. Marschewski, W. Maus-Friedrichs, O. Höfft and F. Endres, e-J. Surf. Sci. Nanotechnol., 2010, 8, 241.] In the present work we analyze these spectra by means of partial density of states (pDOS) as calculated from a single ion pair of the respective ionic liquid using density functional theory (DFT). Subsequently we reconstruct the XPS and UPS spectra by considering photoemission cross sections and analyze the MIES spectra by pDOS, which provides us decisive hints to the ionic liquid surface structure. PMID:21971301

Reinmöller, Markus; Ulbrich, Angela; Ikari, Tomonori; Preiss, Julia; Höfft, Oliver; Endres, Frank; Krischok, Stefan; Beenken, Wichard J D

2011-11-21

302

Novel halogen-free chelated orthoborate-phosphonium ionic liquids: synthesis and tribophysical properties.  

PubMed

We report on the synthesis, characterisation, and physical and tribological properties of halogen-free ionic liquids based on various chelated orthoborate anions with different phosphonium cations, both without halogen atoms in their structure. Important physical properties of the ILs including glass transition temperatures, density, viscosity and ionic conductivity were measured and are reported here. All of these new halogen-free orthoborate ionic liquids (hf-BILs) are hydrophobic and hydrolytically stable liquids at room temperature. As lubricants, these hf-BILs exhibit considerably better antiwear and friction reducing properties under boundary lubrication conditions for steel-aluminium contacts as compared with fully formulated (15W-50 grade) engine oil. Being halogen free these hf-BILs offer a more environmentally benign alternative to ILs being currently developed for lubricant applications. PMID:21687897

Shah, Faiz Ullah; Glavatskih, Sergei; MacFarlane, Douglas R; Somers, Anthony; Forsyth, Maria; Antzutkin, Oleg N

2011-07-28

303

Novel hydrophobic ionic liquids electrolyte based on cyclic sulfonium used in dye-sensitized solar cells  

SciTech Connect

A novel series of hydrophobic room temperature ionic liquids based on six cyclic sulfonium cations were first time synthesized and applied in dye-sensitized solar cells as pure solvents for electrolyte system. The chronoamperograms result showed that the length of substituent on sulfonium cations could inhibit the I{sub 3}{sup -} diffusion and the five-ring structure of sulfonium was benefit for fast triiodide ion diffusion. The electrochemical impendence spectra measurement of dye-sensitized solar cells with these ionic liquid electrolytes was carried out and the result indicated that the cations' structure had indeed influence on the cells' performance especially for the fill factor, which was further proved by the measurement result of I-V curves of these dye-sensitized solar cells. The conclusion was obtained that the electron exchange reaction on Pt counter electrode/electrolyte interface dominated the cells' performance for these ionic liquid electrolyte-based DSCs. (author)

Guo, Lei; Pan, Xu; Wang, Meng; Zhang, Changneng; Fang, Xiaqin; Chen, Shuanghong; Dai, Songyuan [Key Lab of Novel Thin Film Solar Cells, Institute of Plasma Physics, Chinese Academy of Sciences, P.O. Box 1126, Hefei, Anhui 230031 (China)

2011-01-15

304

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

2005-06-01

305

Room-temperature single-photon sources with definite circular and linear polarizations based on single-emitter fluorescence in liquid crystal hosts  

NASA Astrophysics Data System (ADS)

Definite circular and linear polarizations of room-temperature single-photon sources, which can serve as polarization bases for quantum key distribution, are produced by doping planar-aligned liquid crystal hosts with single fluorescence emitters. Chiral 1-D photonic bandgap microcavities for a single handedness of circularly polarized light were prepared from both monomeric and oligomeric cholesteric liquid crystals. Fluorescent emitters, such as nanocrystal quantum dots, nitrogen vacancy color centers in nanodiamonds, and rare-earth ions in nanocrystals, were doped into these microcavity structures and used to produce circularly polarized fluorescence of definite handedness. Additionally, we observed circularly polarized resonances in the spectrum of nanocrystal quantum dot fluorescence at the edge of the cholesteric microcavity's photonic stopband. For this polarization we obtained a ~4.9 enhancement of intensity compared to the polarization of the opposite handedness that propagates without photonic bandgap microcavity effects. Such a resonance is indicative of coupling of quantum dot fluorescence to the cholesteric microcavity mode. We have also used planar-aligned nematic liquid crystal hosts to align DiI dye molecules doped into the host, thereby providing a single-photon source of linear polarization of definite direction. Antibunching is demonstrated for fluorescence of nanocrystal quantum dots, nitrogen vacancy color centers, and dye molecules in these liquid crystal structures.

Winkler, Justin M.; Lukishova, Svetlana G.; Bissell, Luke J.

2013-02-01

306

The preparation of quaternary ammonium-based ionic liquid containing a cyano group and its properties in a lithium battery electrolyte  

Microsoft Academic Search

A room temperature ionic liquid consisting of N,N,N,N-cyanomethyl trimethyl ammonium (CTMA) cation and bis(trifluoromethane sulfone)imide (TFSI) anion was newly synthesized, and its electrochemical properties were investigated. This ionic liquid has a melting point of 35°C and an order of conductivity of 10?4Scm?1. Lithium deposition\\/dissolution tests in 0.2moldm?3 LiTFSI\\/CTMATFSI electrolytes showed an improved cycle behavior compared with that of a Li

Minato Egashira; Shigeto Okada; Jun-ichi Yamaki; Diego Alejandro Dri; Francesco Bonadies; Bruno Scrosati

2004-01-01

307

Lithium cation conducting TDI anion-based ionic liquids.  

PubMed

In this paper we present the synthesis route and electrochemical properties of new class of ionic liquids (ILs) obtained from lithium derivate TDI (4,5-dicyano-2-(trifluoromethyl)imidazolium) anion. ILs synthesized by us were EMImTDI, PMImTDI and BMImTDI, i.e. TDI anion with 1-alkyl-3-methylimidazolium cations, where alkyl meant ethyl, propyl and butyl groups. TDI anion contains fewer fluorine atoms than LiPF6 and thanks to C-F instead of P-F bond, they are less prone to emit fluorine or hydrogen fluoride due to the rise in temperature. Use of IL results in non-flammability, which is making such electrolyte even safer for both application and environment. The thermal stability of synthesized compounds was tested by DSC and TGA and no signal of decomposition was observed up to 250 °C. The LiTDI salt was added to ILs to form complete electrolytes. The structures of tailored ILs with lithium salt were confirmed by X-ray diffraction patterns. The electrolytes showed excellent properties regarding their ionic conductivity (over 3 mS cm(-1) at room temperature after lithium salt addition), lithium cation transference number (over 0.1), low viscosity and broad electrochemical stability window. The ionic conductivity and viscosity measurements of pure ILs are reported for reference. PMID:24803282

Niedzicki, Leszek; Karpierz, Ewelina; Zawadzki, Maciej; Dranka, Maciej; Kasprzyk, Marta; Zalewska, Aldona; Marcinek, Marek; Zachara, Janusz; Doma?ska, Urszula; Wieczorek, W?adys?aw

2014-06-21

308

Modeling Liquid-Liquid Equilibrium of Ionic Liquid Systems with NRTL, Electrolyte-NRTL, and UNIQUAC  

E-print Network

Modeling Liquid-Liquid Equilibrium of Ionic Liquid Systems with NRTL, Electrolyte-NRTL, and UNIQUAC: markst@nd.edu #12;Abstract Characterization of liquid-liquid equilibrium (LLE) in system containing ionic; Ionic liquids; Octanol-water partition coefficients; Excess Gibbs energy models; Electrolyte models #12

Stadtherr, Mark A.

309

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.

2007-01-01

310

Fragility, Stokes-Einstein violation, and correlated local excitations in a coarse-grained model of an ionic liquid  

E-print Network

Dynamics of a coarse-grained model for the room-temperature ionic liquid, 1-ethyl-3-methylimidazolium hexafluorophosphate, couched in the united-atom site representation are studied via molecular dynamics simulations. The dynamically heterogeneous behavior of the model resembles that of fragile supercooled liquids. At or close to room temperature, the model ionic liquid exhibits slow dynamics, characterized by nonexponential structural relaxation and subdiffusive behavior. The structural relaxation time, closely related to the viscosity, shows a super-Arrhenius behavior. Local excitations, defined as displacement of an ion exceeding a threshold distance, are found to be mainly responsible for structural relaxation in the alternating structure of cations and anions. As the temperature is lowered, excitations become progressively more correlated. This results in the decoupling of exchange and persistence times, reflecting a violation of the Stokes-Einstein relation.

Daun Jeong; M. Y. Choi; Hyung. J. Kim; YounJoon Jung

2010-02-03

311

Effect of Embedded Pd Microstructures on the Flat-Band-Voltage Operation of Room Temperature ZnO-Based Liquid Petroleum Gas Sensors  

PubMed Central

Three methods were used to fabricate ZnO-based room temperature liquid petroleum gas (LPG) sensors having interdigitated metal-semiconductor-metal (MSM) structures. Specifically, devices with Pd Schottky contacts were fabricated with: (1) un-doped ZnO active layers; (2) Pd-doped ZnO active layers; and (3) un-doped ZnO layers on top of Pd microstructure arrays. All ZnO films were grown on p-type Si(111) substrates by the sol-gel method. For devices incorporating a microstructure array, Pd islands were first grown on the substrate by thermal evaporation using a 100 ?m mesh shadow mask. We have estimated the sensitivity of the sensors for applied voltage from –5 to 5 V in air ambient, as well as with exposure to LPG in concentrations from 500 to 3,500 ppm at room temperature (300 K). The current-voltage characteristics were studied and parameters such as leakage current, barrier height, reach-through voltage, and flat-band voltage were extracted. We include contributions due to the barrier height dependence on the electric field and tunneling through the barrier for the studied MSM devices. The Pd-enhanced devices demonstrated a maximum gas response at flat-band voltages. The study also revealed that active layers consisting of Pd microstructure embedded ZnO films resulted in devices exhibiting greater gas-response as compared to those using Pd-doped ZnO thin films or un-doped active layers.

Ali, Ghusoon M.; Thompson, Cody V.; Jasim, Ali K.; Abdulbaqi, Isam M.; Moore, James C.

2013-01-01

312

Surface confined ionic liquid as a stationary phase for HPLC  

SciTech Connect

Trimethoxysilane ionosilane derivatives of room temperature ionic liquids based on alkylimidazolium bromides were synthesized for attachment to silica support material. The derivatives 1-methyl-3-(trimethoxysilylpropyl)imidazolium bromide and 1-butyl-3-(trimethoxysilylpropyl)imidazolium bromide were used to modify the surface of 3 {micro}m diameter silica particles to act as the stationary phase for HPLC. The modified particles were characterized by thermogravimetric analysis (TGA) and {sup 13}C and {sup 29}Si NMR spectroscopies. The surface modification procedure rendered particles with a surface coverage of 0.84 {micro}mol m{sup -2} for the alkylimidazolium bromide. The ionic liquid moiety was predominantly attached to the silica surface through two siloxane bonds of the ionosilane derivative (63%). Columns packed with the modified silica material were tested under HPLC conditions. Preliminary evaluation of the stationary phase for HPLC was performed using aromatic carboxylic acids as model compounds. The separation mechanism appears to involve multiple interactions including ion exchange, hydrophobic interaction, and other electrostatic interactions.

Wang, Qian [University of Buffalo, The State University of New York; Baker, Gary A [ORNL; Baker, Sheila N [ORNL; Colon, Luis [Los Alamos National Laboratory (LANL)

2006-01-01

313

Spatial-decomposition analysis of electrical conductivity in ionic liquid  

NASA Astrophysics Data System (ADS)

The electrical conductivity of room temperature ionic liquid (IL) is investigated with molecular dynamics simulation. A trajectory of 1 ?s in total is analyzed for the ionic liquid [C4mim][NTf2] (1-n-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide, and the anion is also called TFSI or TFSA), and the ion motions are examined in direct connection to the conductivity within the framework formulated previously [K.-M. Tu, R. Ishizuka, and N. Matubayasi, J. Chem. Phys. 141, 044126 (2014)]. As a transport coefficient, the computed electrical conductivity is in fair agreement with the experiment. The conductivity is then decomposed into the autocorrelation term of Nernst-Einstein form and the cross-correlation term describing the two-body motions of ions, and the cross-correlation term is further decomposed spatially to incorporate the structural insights on ion configurations into the dynamic picture. It is observed that the ion-pair contribution to the conductivity is not spatially localized and extends beyond the first coordination shell. The extent of localization of the cross-correlation effect in the conductivity is in correspondence to that of the spatial correlation represented by radial distribution function, which persists over nanometer scale.

Tu, Kai-Min; Ishizuka, Ryosuke; Matubayasi, Nobuyuki

2014-12-01

314

Alkaline ionic liquids applied in supported ionic liquid catalyst for selective hydrogenation of citral to citronellal  

PubMed Central

The challenge in preparation of ionic liquids containing a strong alkaline anion is to identify a suitable cation which can tolerate the harsh conditions induced by the anion. In this study, a commercial quaternary ammonium compound (quat) benzalkonium [ADBA] (alkyldimethylbenzylammonium) was used as a cation in the synthesis of different alkaline ionic liquids. In fact, the precursor, benzalkonium chloride, is a mixture of alkyldimethylbenzylammonium chlorides of various alkyl chain lengths and is commonly used in the formulation of various antiseptic products. The prepared ionic liquids were utilized as Supported Ionic Liquid Catalysts (SILCAs). Typically, a SILCA contains metal nanoparticles, enzymes, or metal complexes in an ionic liquid layer which is immobilized on a solid carrier material such as an active carbon cloth (ACC). The catalysts were applied in the selective hydrogenation of citral to citronellal which is an important perfumery chemical. Interestingly, 70% molar yield toward citronellal was achieved over a catalyst containing the alkaline ionic liquid benzalkonium methoxide. PMID:24790972

Salminen, Eero; Virtanen, Pasi; Mikkola, Jyri-Pekka

2014-01-01

315

Alkaline ionic liquids applied in supported ionic liquid catalyst for selective hydrogenation of citral to citronellal.  

PubMed

The challenge in preparation of ionic liquids containing a strong alkaline anion is to identify a suitable cation which can tolerate the harsh conditions induced by the anion. In this study, a commercial quaternary ammonium compound (quat) benzalkonium [ADBA] (alkyldimethylbenzylammonium) was used as a cation in the synthesis of different alkaline ionic liquids. In fact, the precursor, benzalkonium chloride, is a mixture of alkyldimethylbenzylammonium chlorides of various alkyl chain lengths and is commonly used in the formulation of various antiseptic products. The prepared ionic liquids were utilized as Supported Ionic Liquid Catalysts (SILCAs). Typically, a SILCA contains metal nanoparticles, enzymes, or metal complexes in an ionic liquid layer which is immobilized on a solid carrier material such as an active carbon cloth (ACC). The catalysts were applied in the selective hydrogenation of citral to citronellal which is an important perfumery chemical. Interestingly, 70% molar yield toward citronellal was achieved over a catalyst containing the alkaline ionic liquid benzalkonium methoxide. PMID:24790972

Salminen, Eero; Virtanen, Pasi; Mikkola, Jyri-Pekka

2014-01-01

316

Alkaline ionic liquids applied in supported ionic liquid catalyst for selective hydrogenation of citral to citronellal  

NASA Astrophysics Data System (ADS)

The challenge in preparation of ionic liquids containing a strong alkaline anion is to identify a suitable cation which can tolerate the harsh conditions induced by the anion. In this study, a commercial quaternary ammonium compound (quat) benzalkonium [ADBA] (alkyldimethylbenzylammonium) was used as a cation in the synthesis of different alkaline ionic liquids. In fact, the precursor, benzalkonium chloride, is a mixture of alkyldimethylbenzylammonium chlorides of various alkyl chain lengths and is commonly used in the formulation of various antiseptic products. The prepared ionic liquids were utilized as Supported Ionic Liquid Catalysts (SILCAs). Typically, a SILCA contains metal nanoparticles, enzymes or metal complexes in an ionic liquid layer which is immobilized on a solid carrier material such as an active carbon cloth (ACC). The catalysts were applied in the selective hydrogenation of citral to citronellal which is an important perfumery chemical. Interestingly, 70 % molar yield towards citronellal was achieved over a catalyst containing the alkaline ionic liquid benzalkonium methoxide.

Salminen, Eero; Virtanen, Pasi; Mikkola, Jyri-Pekka

2014-02-01

317

Task-Specific Ionic Liquids for Mars Exploration (Green Chemistry for a Red Planet)  

NASA Technical Reports Server (NTRS)

Ionic Liquids (ILs) are organic salts with low melting points that are liquid at or near room temperature. The combinations of available ions and task-specific molecular designability make them suitable for a huge variety of tasks. Because of their low flammability, low vapor pressure, and stability in harsh environments (extreme temperatures, hard vacuum) they are generally much safer and "greener" than conventional chemicals and are thus suitable for a wide range of applications that support NASA exploration goals. This presentation describes several of the ongoing applications that are being developed at MSFC.

Karr, L. J.; Curreri, P. A.; Paley, M. S.; Kaukler, W. F.; Marone, M. J.

2012-01-01

318

Liquid metal alloy ion source based metal ion injection into a room-temperature electron beam ion source  

SciTech Connect

We have carried out a series of measurements demonstrating the feasibility of using the Dresden electron beam ion source (EBIS)-A, a table-top sized, permanent magnet technology based electron beam ion source, as a charge breeder. Low charged gold ions from an AuGe liquid metal alloy ion source were injected into the EBIS and re-extracted as highly charged ions, thereby producing charge states as high as Au{sup 60+}. The setup, the charge breeding technique, breeding efficiencies as well as acceptance and emittance studies are presented.

Thorn, A.; Ritter, E.; Zschornack, G. [Fachrichtung Physik, Technische Universitaet Dresden, Helmholtzstrasse 10, D-01069 Dresden (Germany); Ullmann, F. [DREEBIT GmbH, Zur Wetterwarte 50, D-01109 Dresden (Germany); Pilz, W.; Bischoff, L. [Helmholtzzentrum Dresden-Rossendorf, Bautzner Landstrasse 400, D-01328 Dresden (Germany)

2012-02-15

319

Room TemperatureRoom Temperature Superconductivity ND'05Superconductivity ND'05  

E-print Network

Room TemperatureRoom Temperature Superconductivity ND'05Superconductivity ND'05 Probing Room Temperature SuperconductivityProbing Room Temperature Superconductivity In A Parallel, Wiser Universe #12;Room TemperatureRoom Temperature Superconductivity ND'05Superconductivity ND'05 #12;Room

Islam, M. Saif

320

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

2012-02-22

321

Ab initio study of EMIM-BF4 crystal interaction with a Li (100) surface as a model for ionic liquid\\/Li interfaces in Li-ion batteries  

Microsoft Academic Search

We examined the atomic and electronic structures of an interface between a 1-ethyl-3-methyl imidazolium tetrafluoroborate (EMIM-BF4) ionic-liquid crystal and a Li(100) surface by periodic density-functional calculations, as a model for a room-temperature ionic-liquid (RTIL) electrolyte\\/Li interface at a Li-ion battery electrode. Results are compared with our previous theoretical study of the EMIM-BF4 molecular adsorption on Li surfaces [H. Valencia et

Hubert Valencia; Masanori Kohyama; Shingo Tanaka; Hajime Matsumoto

2009-01-01

322

Ionic Liquids as Extracting Agents for Heavy Metals  

Microsoft Academic Search

The development of applications of ionic liquids in extraction processes stretches back to the mid-1960s when the first studies on ionic liquid- based extractions were published. Since then, the interest of both academics and the industrial community on the development of ionic liquids-based technologies is continuously growing. The main driving force of ionic liquid engineering is to combine their “environmentally

Anja Stojanovic; Bernhard K. Keppler

2012-01-01

323

Friedel-Crafts Acylation of Aromatic Compounds in Ionic Liquids  

Microsoft Academic Search

This article first reviews the application of ionic liquids in Friedel-Crafts acylation reactions. Ionic liquids can be used as catalyst solvents, the active component on solid carriers, or just as the solvent. One advantage of using ionic liquids in acylation reactions is the enhanced reaction rates, conversion, and selectivity. The acylation mechanisms of aromatic compounds in ionic liquids are also

Z. C. Liu; X. H. Meng; R. Zhang; C. M. Xu

2009-01-01

324

Ionic liquid ultrasound assisted dispersive liquid-liquid microextraction method for preconcentration of trace amounts of rhodium prior to flame atomic absorption spectrometry determination.  

PubMed

In this article, we consider ionic liquid based ultrasound-assisted dispersive liquid-liquid microextraction of trace amounts of rhodium from aqueous samples and show that this is a fast and reliable sample pre-treatment for the determination of rhodium ions by flame atomic absorption spectrometry. The Rh(III) was transferred into its complex with 2-(5-bromo-2-pyridylazo)-5-diethylamino phenol as a chelating agent, and an ultrasonic bath with the ionic liquid, 1-octyl-3-methylimidazolium bis (trifluoromethylsulfonyl) imide at room temperature was used to extract the analyte. The centrifuged rhodium complex was then enriched in the form of ionic liquid droplets and prior to its analysis by flame atomic absorption spectrometry, 300 ?L ethanol was added to the ionic liquid-rich phase. Finally, the influence of various parameters on the recovery of Rh(III) was optimized. Under optimum conditions, the calibration graph was linear in the range of 4.0-500.0 ng mL(-1), the detection limit was 0.37 ng mL(-1) (3S(b)/m, n = 7) and the relative standard deviation was ±1.63% (n = 7, C = 200 ng mL(-1)). The results show that ionic liquid based ultrasound assisted dispersive liquid-liquid microextraction, combined with flame atomic absorption spectrometry, is a rapid, simple, sensitive and efficient analytical method for the separation and determination of trace amounts of Rh(III) ions with minimum organic solvent consumption. PMID:20971554

Molaakbari, Elaheh; Mostafavi, Ali; Afzali, Daryoush

2011-01-30

325

High current density electrodeposition from silver complex ionic liquids.  

PubMed

Liquid metal salts are electrolytes with the highest possible metal concentration for electrodeposition, because the metal ion is an integral part of the solvent. This paper introduces the new ionic silver complexes [Ag(MeCN)(4)](2)[Ag(Tf(2)N)(3)], [Ag(MeCN)][Tf(2)N] and [Ag(EtIm)(2)][Tf(2)N], where MeCN stands for acetonitrile, EtIm for 1-ethylimidazole and Tf(2)N is bis(trifluoromethylsulfonyl)imide. These complexes have been characterized by differential scanning calorimetry, single crystal X-ray crystallography, thermogravimetrical analysis, Raman spectroscopy and cyclic voltammetry. [Ag(MeCN)(4)](2)[Ag(Tf(2)N)(3)] is a room temperature ionic liquid. Smooth silver layers of good quality could be deposited from it, at current densities of up to 25 A dm(-2) in unstirred solutions. [Ag(EtIm)(2)][Tf(2)N] melts at 65 °C and can be used as an electrolyte for silver deposition above this temperature. [Ag(MeCN)][Tf(2)N] has a melting point that is too high to be useful in electrodeposition. Addition of thiourea or 1H-benzotriazole to the electrolyte decreased the surface roughness of the silver coatings. The morphology of the metal layers was investigated by atomic force microscopy (AFM). Adsorption of 1H-benzotriazole on the silver metal surface has been proven by Raman spectroscopy. This work shows the usefulness of additives in improving the quality of metal films electrodeposited from ionic liquids. PMID:22193991

Schaltin, Stijn; Brooks, Neil R; Stappers, Linda; Van Hecke, Kristof; Van Meervelt, Luc; Binnemans, Koen; Fransaer, Jan

2012-02-01

326

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

2008-01-01

327

Superbase-derived protic ionic liquids  

DOEpatents

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.

2013-09-03

328

Ionic liquids in the synthesis of nanoobjects  

NASA Astrophysics Data System (ADS)

Data on the usage of the novel green solvents, ionic liquids, in the synthesis of nanoobjects and their stabilization are considered. The information is structured according to the resulting products of the synthetic processes: nanoparticles of noble metals, nanoparticles of non-metals, nanoparticles of metal oxides and chalcogenides, nanocomposites, and highly dispersed polymers. The conclusion is made that the ionic liquids might determine the structure and the properties of the nanoobjects, thus opening new fundamental and technological horizons in nanochemistry.

Tarasova, Natalia P.; Smetannikov, Yurii V.; Zanin, A. A.

2010-08-01

329

Enzymatic ester synthesis in ionic liquids  

Microsoft Academic Search

Six different ionic liquids based on dialkylimidazolium or quaternary ammonium cations associated with perfluorinated or bis(trifluoromethyl)sulfonyl amide anions were used as reaction media for ester synthesis catalyzed by both free Candida antarctica lipase B and ?-chymotrypsin at 2% (v\\/v) water content and 50°C. All the assayed ionic liquids proved adequate media for enzyme-catalyzed transesterification, and in the case of lipase,

Pedro Lozano; Teresa De Diego; Daniel Carrié; Michel Vaultier; José L Iborra

2003-01-01

330

Synthesis of esters in ionic liquids  

Microsoft Academic Search

Free Candida antarctica lipase B (CALB) was successfully applied to catalyzing the synthesis of alkyl esters by transesterification from vinyl esters and alcohols in ionic liquids based on 1-alkyl-3-methylimidazolium cations ([bmim+] and [omim+]) and the hexafluorophosphate anion ([PF6?]). First, the variables affecting the performance of CALB in transesterification reactions in ionic liquids, temperature and pH, were studied, choosing the synthesis

Antonia P. de los Ríos; Francisco J. Hernández-Fernández; F. Tomás-Alonso; Demetrio Gómez; Gloria Víllora

2008-01-01

331

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.

2005-01-01

332

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.

2006-02-01

333

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

2014-01-01

334

A novel CMPO-functionalized task specific ionic liquid: synthesis, extraction and spectroscopic investigations of actinide and lanthanide complexes.  

PubMed

A novel CMPO (carbamoylmethylphosphine oxide) based task specific ionic liquid (TSIL) with an NTf(2)(-) counter anion was synthesized and evaluated for actinide/lanthanide extraction from acidic feed solutions using several room temperature ionic liquids (RTILs). The extraction data were compared with those obtained with CMPO in the same set of RTILs and also in the molecular diluent, n-dodecane. The extracted species were analyzed by the conventional slope analysis method and the extraction followed an ion-exchange mechanism. The nature of bonding in the extracted complexes was investigated by various spectroscopic techniques such as FT-IR and UV-visible spectroscopy. PMID:23403959

Mohapatra, Prasanta K; Kandwal, Pankaj; Iqbal, Mudassir; Huskens, Jurriaan; Murali, Mallekav S; Verboom, Willem

2013-04-01

335

Separation of plutonium(IV) from uranium(VI) using phosphonate-based task-specific ionic liquid  

Microsoft Academic Search

The extraction behavior of plutonium(IV) and uranium(VI) from nitric acid medium by a solution of diethyl-2-(3-methylimidazolium)ethylphosphonate bis(trifl uoromethanesulfonyl)imide (ImPNTf2) ionic liquid in the room temperature ionic liquid (RTIL), 1-alkyl-3-methylimidazolium bis(trifl uoromethanesulfonyl)imide (alkyl = butyl, hexyl or octyl) was studied. The distribution ratio of Pu(IV) in ImPNTf2\\/amimNTf2 increased with increase in the concentration of nitric acid reached a maximum at 0.5

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

2012-01-01

336

Computer Simulation of a "Green Chemistry" Room-Temperature Ionic Solvent C. J. Margulis, H. A. Stern, and B. J. Berne*  

E-print Network

describes preparation and handling techniques. Physical and chemical properties of some of these solvents scanning calorimetry of some of these ionic organic compounds. Noda and co-workers3 measured H and F NMR. As far as we know, the X-ray crystal structure is available only for a few compounds.4,5 UV-vis, IR6

Berne, Bruce J.

337

Stimuli-responsive block copolymers in ionic liquids  

NASA Astrophysics Data System (ADS)

Ionic liquids (ILs) are room temperature molten salts and have attracted much attention because of their unique properties. The characteristics of ILs (non-volatility, non-flammability, chemical stability, high ionic conductivity) can contribute to high performance energy-conversion materials. On the other hand, some polymers greatly change their solubility in ILs in response to external stimuli such as temperature and light. We have found that poly(N-isopropylacrylamide) (PNIPAm) and poly(benzyl methacrylate) (PBnMA) show upper critical solution temperature (UCST)-type phase behavior and lower critical solution temperature (LCST)-type phase behavior in an ILs, respectively. Most recently, we also discovered that certain polymers change their solubility induced by photo stimuli. In this study, we describe temperature and photo stimuli responsive self-assembly of AB type block copolymers having at least one stimuli-responsive segment in IL solution. Based on the results, we will aply to construct stimuli-responsive physical gels by using ABA tribock copolymer self assembly in an IL.

Ueki, Takeshi; Watanabe, Masayoshi; Lodge, Tim

2008-03-01

338

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

2009-01-11

339

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

PubMed

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

2014-08-14

340

Thermal decomposition mechanisms of alkylimidazolium ionic liquids with cyano-functionalized anions.  

PubMed

Because of the unusually high heats of vaporization of room-temperature ionic liquids (RTILs), volatilization of RTILs through thermal decomposition and vaporization of the decomposition products can be significant. Upon heating of cyano-functionalized anionic RTILs in vacuum, their gaseous products were detected experimentally via tunable vacuum ultraviolet photoionization mass spectrometry performed at the Chemical Dynamics Beamline 9.0.2 at the Advanced Light Source. Experimental evidence for di- and trialkylimidazolium cations and cyano-functionalized anionic RTILs confirms thermal decomposition occurs primarily through two pathways: deprotonation of the cation by the anion and dealkylation of the imidazolium cation by the anion. Secondary reactions include possible cyclization of the cation and C2 substitution on the imidazolium, and their proposed reaction mechanisms are introduced here. Additional evidence supporting these mechanisms was obtained using thermal gravimetric analysis-mass spectrometry, gas chromatography-mass spectrometry, and temperature-jump infrared spectroscopy. In order to predict the overall thermal stability in these ionic liquids, the ability to accurately calculate both the basicity of the anions and their nucleophilicity in the ionic liquid is critical. Both gas phase and condensed phase (generic ionic liquid (GIL) model) density functional theory calculations support the decomposition mechanisms, and the GIL model could provide a highly accurate means to determine thermal stabilities for ionic liquids in general. PMID:25381899

Chambreau, Steven D; Schenk, Adam C; Sheppard, Anna J; Yandek, Gregory R; Vaghjiani, Ghanshyam L; Maciejewski, John; Koh, Christine J; Golan, Amir; Leone, Stephen R

2014-11-26

341

Amorphous silicon thin films as a high capacity anodes for Li-ion batteries in ionic liquid electrolytes  

Microsoft Academic Search

High lithiation capacity at low red-ox potentials in combination with good safety characteristics makes amorphous Si as a very promising anode material for rechargeable Li batteries.Thin film silicon electrodes were prepared by DC magnetron sputtering of silicon on stainless steel substrates. Their behavior as Li insertion\\/extraction electrodes was studied by voltammetry and chronopotentiometry at room temperature in the ionic liquid

V. Baranchugov; E. Markevich; E. Pollak; G. Salitra; D. Aurbach

2007-01-01

342

Anodic behavior of Al current collector in 1-alkyl-3-methylimidazolium bis[(trifluoromethyl)sulfonyl] amide ionic liquid electrolytes  

Microsoft Academic Search

The anodic behaviors of aluminum current collector for lithium ion batteries were investigated in a series of 1-alkyl-3-methylimidazolium bis[(trifluoromethyl)sulfonyl] amide room temperature ionic liquids (RTILs) and EC+DMC electrolytes. It was found that the aluminum corrosion, which occurred in EC+DMC electrolytes containing LiTFSI, was not observed in the RTIL electrolytes. Further research showed that a passive film with amide compounds as

Chengxin Peng; Li Yang; Zhengxi Zhang; Kazuhiro Tachibana; Yong Yang

2007-01-01

343

Room-temperature stabilization of nanoscale superionic Ag?Se.  

PubMed

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 Ag?Se 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 Ag?Se in devices where high ionic conductivity at room temperature is required. PMID:25249347

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

2014-10-17

344

Terpenes to Ionic Liquids: Synthesis and Characterization of Citronellal-Based Chiral Ionic Liquids  

Microsoft Academic Search

A series of new chiral ionic liquids have been prepared and characterized starting from a simple, economical, and commercially available monoterpene, citronellal. The aldehyde functionality in citronellal is converted into a Schiff base using an amine, followed by reduction with Raney nickel to give the desired quaternary amine. Most of the ionic liquids generated using this procedure are found to

D. Nageshwar; D. Muralimohan Rao; Palle V. R. Acharyulu

2009-01-01

345

Ab initio study of EMIM-BF4 molecule adsorption on Li surfaces as a model for ionic liquid\\/Li interfaces in Li-ion batteries  

Microsoft Academic Search

The adsorption of 1-ethyl-3-methyl imidazolium tetrafluoroborate (EMIM-BF4) molecules onto Li (100), (110), and (111) surfaces is investigated by means of periodic density-functional theory calculations as a model for room-temperature ionic liquid\\/Li-metal anode interfaces in a Li-ion battery. We examined the atomic and electronic structures of isolated EMIM+ and BF4- molecules, a pair of [EMIM]+[BF4]- , and Li bulk and surfaces,

Hubert Valencia; Masanori Kohyama; Shingo Tanaka; Hajime Matsumoto

2008-01-01

346

On-line ionic liquid-based preconcentration system coupled to flame atomic absorption spectrometry for trace cadmium determination in plastic food packaging materials  

Microsoft Academic Search

A novel on-line preconcentration method based on liquid–liquid (L–L) extraction with room temperature ionic liquids (RTILs) coupled to flame atomic absorption spectrometry (FAAS) was developed for cadmium determination in plastic food packaging materials. The methodology is based on the complexation of Cd with 2-(5-bromo-2-pyridylazo)-5-diethylaminophenol (5-Br-PADAP) reagent after sample digestion followed by extraction of the complex with the RTIL 1-butyl-3-methylimidazolium hexafluorophosphate

Estefanía M. Martinis; Roberto A. Olsina; Jorgelina C. Altamirano; Rodolfo G. Wuilloud

2009-01-01

347

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

2011-01-01

348

Ionic liquid droplet as e-microreactor.  

PubMed

A powerful approach combining a droplet-based, open digital microfluidic lab-on-a-chip using task-specific ionic liquids as soluble supports to perform solution-phase synthesis is reported as a new tool for chemical applications. The negligible volatility of ionic liquids enables their use as stable droplet reactors on a chip surface under air. The concept was validated with different ionic liquids and with a multicomponent reaction. Indeed, we showed that different ionic liquids can be moved by electrowetting on dielectric (EWOD), and their displacement was compared with aqueous solutions. Furthermore, we showed that mixing ionic liquids droplets, each containing a different reagent, in "open" systems is an efficient way of carrying supported organic synthesis. This was applied to Grieco's tetrahydroquinolines synthesis with different reagents. Analysis of the final product was performed off-line and on-line, and the results were compared with those obtained in a conventional reaction flask. This technology opens the way to easy synthesis of minute amounts of compounds ad libitum without the use of complex, expensive, and bulky robots and allows complete automation of the process for embedded chemistry in a portable device. It offers several advantages, including simplicity of use, flexibility, and scalability, and appears to be complementary to conventional microfluidic lab-on-a-chip devices usually based on continuous-flow in microchannels. PMID:16841910

Dubois, Philippe; Marchand, Gilles; Fouillet, Yves; Berthier, Jean; Douki, Thierry; Hassine, Fatima; Gmouh, Said; Vaultier, Michel

2006-07-15

349

Hydrogen production by water electrolysis using tetra-alkyl-ammonium-sulfonic acid ionic liquid electrolytes  

NASA Astrophysics Data System (ADS)

Triethylammonium-propanesulfonic acid tetrafluoroborate (TEA-PS·BF4) is used as an electrolyte in the water electrolysis. The electrolysis of water with this ionic conductor produces high current densities with high efficiencies, even at room temperatures. A system using TEA-PS·BF4 in an electrochemical cell with platinum electrodes has current densities (i) up to 1.77 A cm-2 and efficiencies between 93 and 99% in temperatures ranging from 25 °C to 80 °C. The activation energy observed with TEA-PS·BF4 is ca. 9.3 kJ mol-1, a low value that can be explained by the facilitation of proton transport in the organised aqueous ionic liquid media. The unexpectedly high efficiency of this system is discussed by taking into account the high conductivities associated with the Brönsted and Lewis acidity characteristics associated with these ionic conductive materials.

Fiegenbaum, Fernanda; Martini, Emilse M.; de Souza, Michèle O.; Becker, Márcia R.; de Souza, Roberto F.

2013-12-01

350

The use of new ionic liquids in two-phase catalytic hydrogenation reaction by rhodium complexes  

Microsoft Academic Search

The reaction of 1-n-butyl-3-methylimidazolium chloride (BMIC) with sodium tetrafluoroborate or sodium hexafluorophosphate produced the room temperature-, air- and water-stable molten salts (BMI+)(BF4?) (1) and (BMI+)(PF6?) (2), respectively, in almost quantitative yield. The rhodium complexes RhCl(PPh3)3 and [Rh(cod)2][BF4] are completely soluble in these ionic liquids and they are able to catalyse the hydrogenation of cyclohexene at 10 atm and 25°C in

Paulo A. Z. Suarez; Jeane E. L. Dullius; Sandra Einloft; Roberto F. De Souza; Jairton Dupont

1996-01-01

351

Single-walled carbon nanotubes modified by ionic liquid as antiwear additives of thermoplastics  

Microsoft Academic Search

Pristine single-walled carbon nanotubes (CNTs) were dispersed in the room-temperature ionic liquid (IL) 1-octyl, 3-methylimidazolium tetrafluoroborate ([OMIM]BF4) by grinding and ultrasounds. Excess IL was removed to obtain single-walled carbon nanotubes modified by [OMIM]BF4 (mCNTs). mCNTs were added in a 1wt.% to polystyrene (PS), polymethylmethacrylate (PMMA) and polycarbonate (PC) to obtain PS+mCNT, PMMA+mCNT and PC+mCNT. The dry tribological performance of the

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

2010-01-01

352

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

PubMed

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

2014-07-25

353

A theoretical analysis of a Diels-Alder reaction in ionic liquids.  

PubMed

The Diels-Alder reaction of cyclopentadinene (CP) with methyl acrylate (MA) in room-temperature ionic liquids (RTILs) is theoretically examined. In the present study, quantum molecular orbital theory is combined with a multicomponent reference interaction site model (RISM). Because RISM is free from statistical error, it is possible to overcome the serious difficulty in the description of the strong Coulombic interaction in RTILs. We focused on the origin of the relatively moderate solvation effects of RTILs and the mechanism of endo-exo selectivity. PMID:19463005

Hayaki, Seigo; Kido, Kentaro; Yokogawa, Daisuke; Sato, Hirofumi; Sakaki, Shigeyoshi

2009-06-18

354

Knoevenagel condensation reaction catalyzed by task-specific ionic liquid under solvent-free conditions  

Microsoft Academic Search

A task-specific ionic liquid, [H3N+–CH2–CH2–OH][CH3COO?] was synthesized and used as catalyst in the Knoevenagel condensation reaction of various kinds of aromatic aldehydes with ethyl cyanoacetate or malononitrile. ?,?-Unsaturated carbonyl compounds were obtained in reasonable yields when the [H3N+–CH2–CH2–OH][CH3COO?] catalyzed Knoevenagel reaction was carried out at room temperature for several to 60min under solvent-free conditions. Only E-isomers were detected. The task-specific

Caibo Yue; Aiqin Mao; Yunyang Wei; Minjie Lü

2008-01-01

355

The thiocyanate anion is a primary driver of carbon dioxide capture by ionic liquids  

NASA Astrophysics Data System (ADS)

Carbon dioxide, CO2, capture by room-temperature ionic liquids (RTILs) is a vivid research area featuring both accomplishments and frustrations. This work employs the PM7-MD method to simulate adsorption of CO2 by 1,3-dimethylimidazolium thiocyanate at 300 K. The obtained result evidences that the thiocyanate anion plays a key role in gas capture, whereas the impact of the 1,3-dimethylimidazolium cation is mediocre. Decomposition of the computed wave function on the individual molecular orbitals confirms that CO2-SCN binding extends beyond just expected electrostatic interactions in the ion-molecular system and involves partial sharing of valence orbitals.

Chaban, Vitaly

2015-01-01

356

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.

2008-01-01

357

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

2008-01-01

358

Stabilization of superionic ?-Agl at room temperature in a glass matrix  

NASA Astrophysics Data System (ADS)

SINCE the discovery1 that the high-temperature phase of silver iodide (?-AgI) has an ionic conductivity comparable to that of the best liquid electrolytes, solid electrolytes have attracted wide interest. Possible applications of these materials range from solid-state batteries to electrochromic displays and sensors2. Although ?-AgI displays conductivities of more than 10 S cm-1 (ref. 3), owing to the almost liquid-like mobility of Ag+ ions, the crystal transforms below 147 °C to the ?-phase with a conductivity of only ~10-5 S cm-1 at room temperature. Efforts to achieve good conductivities at lower temperatures have focused on the addition of a second component to AgI to form solid solutions or new compounds such as RbAg4I5 and Ag2HgI4 (refs 4-7). Here we report our success in depressing the ?-->? transformation temperature so as to stabilize ?-AgI itself at room temperature. We use a melt-quenching technique to prepare crystallites of ?-AgI frozen into a silver borate glass matrix. The quenched material showed diffraction peaks characteristic of ?-AgI and displayed ionic conductivities of about 10-1 S cm-1. Further development of these glass/crystal composites may make the high ionic conductivity of ?-AgI available for room-temperature solid-state applications.

Tatsumisago, Masahiro; Shinkuma, Yoshikane; Minami, Tsutomu

1991-11-01

359

TETRAALKYLPHOSPHONIUM POLYOXOMETALATES AS NOVEL IONIC LIQUIDS.  

SciTech Connect

The pairing of a Lindqvist or Keggin polyoxometalate (POM) anion with an appropriate tetraalkylphosphonium cation, [R{sub 3}R{prime}P]{sup +}, has been shown to yield an original family of ionic liquids (POM-ILs), among them salts liquid at or near ambient temperature. The physicochemical properties of several such 'inorganic liquids', in particular their thermal properties, suggests the possible application of these compounds as robust, thermally-stable solvents for liquid-liquid extraction. A preliminary evaluation of the potential of POM-ILs in this application is presented.

DIETZ,M.L.; RICKERT, P.G.; ANTONIO, M.R.; FIRESTONE, M.A.; WISHART, J.F.; SZREDER, T.

2007-11-30

360

Enzyme activity in dialkyl phosphate ionic liquids.  

PubMed

The activity of four metagenomic enzymes and an enzyme cloned from the straw mushroom, Volvariella volvacea 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. PMID:22001053

Thomas, Marie F; Li, Luen-Luen; Handley-Pendleton, Jocelyn M; van der Lelie, Daniel; Dunn, John J; Wishart, James F

2011-12-01

361

Desulfurization of oxidized diesel using ionic liquids  

NASA Astrophysics Data System (ADS)

The extraction of oxidized sulfur compounds from diesel were carried out using ten types of ionic liquids consisting of different cation and anion i.e. 1-ethyl-3-methylimidazolium tetrafluoroborate, 1-butyl-3-methylimidazoium thiocyanate, 1-butyl-3-methylimidazoium dicyanamide, 1-butyl-3-methylimidazolium trifluoromethanesulfonate, 1-butyl-3-methylimidazoliumhexafluorophosphate, 1-hexyl-3-methylimidazolium trifluoromethanesulfonate, trioctylmethylammonium chloride, 1-propionitrile-3-butylimidazolium thiocyanate, 1-propionitrile-3-butylimidazolium dicyanamide and 1-butyl-6-methylquinolinium dicyanamide. The oxidation of diesel was successfully done using phosphotungstic acid as the catalyst, hydrogen peroxide (H2O2) as the oxidant and trioctylmethylammonium chloride as the phase transfer agent. The oxidation of diesel changes the sulfur compounds into sulfone which increases its polarity and enhances the ionic liquid's extraction performance. Result showed that ionic liquid [C4mquin][N(CN)2] performed the highest sulfur removal (91% at 1:5 diesel:IL ratio) compared to the others.

Wilfred, Cecilia D.; Salleh, M. Zulhaziman M.; Mutalib, M. I. Abdul

2014-10-01

362

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.

2011-12-01

363

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

2008-11-30

364

Ionic liquids as active pharmaceutical ingredients.  

PubMed

Ionic liquids (ILs) are ionic compounds that possess a melting temperature below 100 °C. Their physical and chemical properties are attractive for various applications. Several organic materials that are now classified as ionic liquids were described as far back as the mid-19th century. The search for new and different ILs has led to the progressive development and application of three generations of ILs: 1) The focus of the first generation was mainly on their unique intrinsic physical and chemical properties, such as density, viscosity, conductivity, solubility, and high thermal and chemical stability. 2) The second generation of ILs offered the potential to tune some of these physical and chemical properties, allowing the formation of "task-specific ionic liquids" which can have application as lubricants, energetic materials (in the case of selective separation and extraction processes), and as more environmentally friendly (greener) reaction solvents, among others. 3) The third and most recent generation of ILs involve active pharmaceutical ingredients (API), which are being used to produce ILs with biological activity. Herein we summarize recent developments in the area of third-generation ionic liquids that are being used as APIs, with a particular focus on efforts to overcome current hurdles encountered by APIs. We also offer some innovative solutions in new medical treatment and delivery options. PMID:21557480

Ferraz, Ricardo; Branco, Luís C; Prudêncio, Cristina; Noronha, João Paulo; Petrovski, Zeljko

2011-06-01

365

Performance of Nitrile-Containing Anions in Task-Specific Ionic Liquids for Improved CO2/N2 Separation  

SciTech Connect

This work explores the performance of a series of ionic liquids that incorporate a nitrile-containing anion paired to 1-alkyl-3-methylimidazolium cations in tailoring the selectivity and permeance of supported ionic liquid membranes for CO2/N2 separations. The permeance and selectivity of three ionic liquids, each with an increasing number of nitrile groups in the anion (i.e., two, three, and four), were measured using a non-steady-state permeation method. By predictably varying the molar volume and viscosity of the ionic liquids, we show that the solubility, selectivity, and permeance can be optimized for CO2/N2 separation through controlled introduction of the nitrile functionality into the anion. Of the three nitrile-based ionic liquids studied, 1-ethyl-3-methylimidazolium tetracyanoborate, [emim][B(CN)4], showed the highest permeance with a value of 2.55 10 9 mol/(m2 Pa s), a magnitude 30% higher than that of the popular ionic liquid [emim][Tf2N]. This same nitrile-bearing ionic liquid also exhibited a high CO2/N2 selectivity of approximately 53. Additionally, the carbon dioxide solubility for each ionic liquid was measured at room temperature with [emim][B(CN)4] again exhibiting the highest CO2 solubility. Results from our study of the nitrile-based ionic liquids can be rationalized in terms of regular solution theory wherein the selectivity and permeance of a given SILM system are largely determined by the molar volume and viscosity of the corresponding ionic liquid phase.

Mahurin, Shannon Mark [ORNL; Lee, Jeseung [ORNL; Baker, Gary A [ORNL; Luo, Huimin [ORNL; Dai, Sheng [ORNL

2010-01-01

366

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

PubMed

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

2014-12-01

367

A novel mechanism for the extraction of metals from water to ionic liquids.  

PubMed

We present a novel mechanism for the extraction of metals from aqueous phases to room-temperature ionic liquids (ILs) by use of a high-temperature salt as an extraction agent. The mechanism capitalizes on the fact that charged metal complexes are soluble in ILs; this allows for extraction of charged complexes rather than the neutral species, which are formed by conventional approaches. The use of a well-chosen extraction agent also suppresses the competing ion-exchange mechanism, thus preventing degradation of the ionic liquid. The approach permits the use of excess extractant to drive the recovery of metals in high yield. This work presents both a thermodynamic framework for understanding the approach and experimental verification of the process in a range of different ILs. The method has great potential value in the recovery of metals, water purification and nuclear materials processing. PMID:24590618

Janssen, Camiel H C; Sánchez, Antonio; Witkamp, Geert-Jan; Kobrak, Mark N

2013-11-11

368

Synthesis and characterisations of Aliquat 336® and cetylpyridinium ionic liquids incorporated with sulfonate-based anions  

NASA Astrophysics Data System (ADS)

A novel series of ionic liquids based on the tricaprylmethylammonium cation [C25H54N+], in Aliquat 336® and cetylpyridinium cation [C21H38N+] in cetylpyridinium chloride incorporating sulfonate-based anions were elegantly prepared by means of ion exchange between the Cl- cation with two different anions, namely, dioctylsulfosuccinate [DOSS-] and dihexylsulfosuccinate [HOSS-]. These ionic liquids were characterised using FTIR-ATR and NMR in order to identify the molecular structures of these compounds. The physical properties of these compounds, namely refractive index and thermal properties were measured at room temperature and are reported herein. ILs incorporating cetylpyridinium cations show higher thermal stability and refractive index values as compared to Aliquat ILs due to the effects of the aromatic ring on the cetylpyridinium cation as well as the longer alkyl chain on the anion of DOSS.

Wilfred, Cecilia Devi; Nair, G. Divya; Ziyada, Abobakr Khidir

2012-09-01

369

Electrochemical and physicochemical properties of small phosphonium cation ionic liquid electrolytes with high lithium salt content.  

PubMed

Electrolytes of a room temperature ionic liquid (RTIL), trimethyl(isobutyl)phosphonium (P111i4) bis(fluorosulfonyl)imide (FSI) with a wide range of lithium bis(fluorosulfonyl)imide (LiFSI) salt concentrations (up to 3.8 mol kg(-1) of salt in the RTIL) were characterised using a combination of techniques including viscosity, conductivity, differential scanning calorimetry (DSC), electrochemical impedance spectroscopy (EIS), nuclear magnetic resonance (NMR) and cyclic voltammetry (CV). We show that the FSI-based electrolyte containing a high salt concentration (e.g. 1?:?1 salt to IL molar ratio, equivalent to 3.2 mol kg(-1) of LiFSI) displays unusual transport behavior with respect to lithium ion mobility and promising electrochemical behavior, despite an increase in viscosity. These electrolytes could compete with the more traditionally studied nitrogen-based ionic liquids (ILs) in lithium battery applications. PMID:25820549

Girard, G M A; Hilder, M; Zhu, H; Nucciarone, D; Whitbread, K; Zavorine, S; Moser, M; Forsyth, M; MacFarlane, D R; Howlett, P C

2015-04-14

370

Tunable amphiphilicity and multifunctional applications of ionic-liquid-modified carbon quantum dots.  

PubMed

During the past decade, increasing attention has been paid to photoluminescent nanocarbon materials, namely, carbon quantum dots (CQDs). It is gradually accepted that surface engineering plays a key role in regulating the properties and hence the applications of the CQDs. In this paper, we prepared highly charged CQDs through a one-pot pyrolysis with citric acid as carbon source and a room-temperature imidazolium-based ionic liquid as capping agent. The as-prepared CQDs exhibit high quantum yields up to 25.1% and are stable under various environments. In addition, the amphiphilicity of the CQDs can be facilely tuned by anion exchange, which leads to a spontaneous phase transfer between water and oil phase. The promising applications of the CQDs as ion sensors and fluorescent inks have been demonstrated. In both cases, these ionic-liquid-modified CQDs were found to possess novel characteristics and/or superior functions compared to existing ones. PMID:25774972

Wang, Baogang; Song, Aixin; Feng, Lei; Ruan, Hong; Li, Hongguang; Dong, Shuli; Hao, Jingcheng

2015-04-01

371

Saturation properties of 1-alkyl-3-methylimidazolium based ionic liquids.  

PubMed

We study the liquid-vapor saturation properties of room temperature ionic liquids (RTILs) belonging to the homologous series 1-alkyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ([Cnmim][NTf2]) using Monte Carlo simulation. We examine the effect of temperature and cation alkyl chain length n on the saturated densities, vapor pressures, and enthalpies of vaporization. These properties are explicitly calculated for temperatures spanning from 280 to 1000 K for RTILs with n = 2, 4, 6, 8, 10, and 12. We also explore how the identity of the anion influences saturation properties. Specifically, we compare results for [C(4)mim][NTf2] with those for 1-butyl-3-methylimidazolium tetrafluoroborate ([C(4)mim][BF4]) and 1-butyl-3-methylimidazolium hexafluorophosphate ([C(4)mim][PF6]). Simulations are completed with a recently developed realistic united-atom force field. A combination of direct grand canonical and isothermal-isobaric temperature expanded ensemble simulations are used to construct phase diagrams. Our results are compared with experimental data and Gibbs ensemble simulation data. Overall, we find good agreement between our results and those measured experimentally. We find that the vapor pressures and enthalpies of vaporization show a strong dependence on the size of the alkyl chain at low temperatures, whereas no particular trend is observed at high temperatures. Finally, we also discuss the effect of temperature on liquid phase nanodomains observed in RTILs with large hydrophobic groups. We do not observe a drastic change in liquid phase structure upon variation of the temperature, which suggests there is not a sharp phase transition between a nanostructured and homogeneous liquid, as has been suggested in earlier studies. PMID:24986360

Rane, Kaustubh S; Errington, Jeffrey R

2014-07-24

372

Unravelling Nanoconfined Films of Ionic Liquids  

E-print Network

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 relative to thermal energy, 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; Perkin, Susan; Goriely, Alain

2014-01-01

373

Unravelling Nanoconfined Films of Ionic Liquids  

E-print Network

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 relative to thermal energy, 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.

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

2014-08-01

374

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

2006-01-01

375

Improved adhesive for cryogenic applications cures at room temperature  

NASA Technical Reports Server (NTRS)

Adhesive cured at room temperature provides an effective adhesive bond over the range from room temperature down to the temperature of liquid hydrogen. The adhesive consists of one part of 200-mesh powdered nylon filler to two parts of an epoxy-polyamine resin.

Klinger, H. J.; Smith, M. B.

1966-01-01

376

Transparent ionic liquid-phenol resin hybrids with high ionic conductivity  

Microsoft Academic Search

We report transparent ion conductive ionic liquid-phenol resin hybrids prepared by in situ polymerization\\/crosslinking of phenol monomer in ionic liquid. As ionic liquid, we used highly ion conductive ionic liquid 1-ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)amide ([EMI][TFSA]). Simultaneous polymerization and crosslinking of phenol with paraformaldehyde in [EMI][TFSA] yielded a highly transparent film. From a field emission scanning electron microscope (FE-SEM) image at 5000 magnification,

Tomoki Ogoshi; Takeshi Onodera; Tada-aki Yamagishi; Yoshiaki Nakamoto; Akihito Kagata; Noriyoshi Matsumi; Keigo Aoi

2011-01-01

377

EXPEDITIOUS SYNTHESIS OF IONIC LIQUIDS USING ULTRASOUND AND MICROWAVE IRRADIATION  

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...

378

Ionic Liquids and New Proton Exchange Membranes for Fuel Cells  

NASA Technical Reports Server (NTRS)

There is currently a great surge of activity in fuel cell research as laboratories across the world seek to take advantage of the high energy capacity provided by &el cells relative to those of other portable electrochemical power systems. Much of this activity is aimed at high temperature fie1 cells, and a vital component of such &el cells must be the availability of a high temperature stable proton-permeable membrane. NASA Glenn Research Center is greatly involved in developing this technology. Other approaches to the high temperature fuel cell involve the use of single- component or almost-single-component electrolytes that provide a path for protons through the cell. A heavily researched case is the phosphoric acid fuel cell, in which the electrolyte is almost pure phosphoric acid and the cathode reaction produces water directly. The phosphoric acid fie1 cell delivers an open circuit voltage of 0.9 V falling to about 0.7 V under operating conditions at 170 C. The proton transport mechanism is mainly vehicular in character according to the viscosity/conductance relation. Here we describe some Proton Transfer Ionic Liquids (PTILs) with low vapor pressure and high temperature stability that have conductivities of unprecedented magnitude for non-aqueous systems. The first requirement of an ionic liquid is that, contrary to experience with most liquids consisting of ions, it must have a melting point that is not much above room temperature. The limit commonly suggested is 100 C. PTILs constitute an interesting class of non-corrosive proton-exchange electrolyte, which can serve well in high temperature (T = 100 - 250 C) fuel cell applications. We will present cell performance data showing that the open circuit voltage output, and the performance of a simple H2(g)Pt/PTIL/Pt/O2(g) fuel cell may be superior to those of the equivalent phosphoric acid electrolyte fuel cell both at ambient temperature and temperatures up to and above 200 C. My work at NASA Glenn Research Center during this summer is to develop and characterize proton exchange membranes doped with ionic liquids. The main techniques used to characterize these materials are: Impedance Spectroscopy, NMR, DSC, TGA, DMA, IR, and SEM ...

Belieres, Jean-Philippe

2004-01-01

379

Task-specific microextractions using ionic liquids.  

PubMed

Ionic liquids (ILs) have been the focus of many scientific investigations including the field of analytical microextractions. ILs have many advantages over traditional organic solvents making them excellent candidates as extraction media for a variety of microextraction techniques. Many physical properties of ILs can be varied, and the structural design and make-up can be tuned to impart desired functionality for enhancement of analyte extraction selectivity, efficiency, and sensitivity. This paper provides a brief overview of ionic liquids and highlights trends in three important sample-preparation techniques, namely, single drop microextraction, solid-phase microextraction, and dispersive liquid-liquid microextraction in terms of performing task-specific extractions using these highly versatile solvents. PMID:21400073

Zhao, Qichao; Anderson, Jared L

2011-06-01

380

Thermal properties of imidazolium ionic liquids  

Microsoft Academic Search

We investigated the thermal properties of several imidazolium salts using DSC and TGA\\/SDTA data. Many of these salts are liquids at sub-ambient temperatures. These ionic liquids form glasses at low temperatures and have minimal vapor pressure up to their thermal decomposition temperature (>400°C). Thermal decomposition is endothermic with the inorganic anions and exothermic with the organic anions investigated. Halide anions

Helen L Ngo; Karen LeCompte; Liesl Hargens; Alan B McEwen

2000-01-01

381

1,2,3-triazolium ionic liquids  

DOEpatents

The present invention relates to compositions of matter that are ionic liquids, the compositions comprising substituted 1,2,3-triazolium cations combined with any anion. Compositions of the invention should be useful in the separation of gases and, perhaps, as catalysts for many reactions.

Luebke, David; Nulwala, Hunaid; Tang, Chau

2014-12-09

382

New developments in catalysis using ionic liquids  

Microsoft Academic Search

Ionic liquids are low melting point salts that represent an exciting new class of reaction solvents for catalysis. Being composed entirely of ions, they possess negligible vapour pressures, and the wide range of possible cations and anions means that other solvent properties may be easily controlled. There is currently great interest in the use of these materials as solvents for

Charles M. Gordon

2001-01-01

383

Reactions of Starch in Ionic Liquids  

Technology Transfer Automated Retrieval System (TEKTRAN)

We found that starches are found to be soluble at 80 ºC in ionic liquids such as 1-butyl-3-methylimidazolium chloride (BMIMCl) and 1-butyl-3-methylimidazolium dicyanamide (BMIMdca) in concentration up to 10% (w/w). Higher concentrations of biopolymers in these novel solvents resulted in solutions w...

384

Esterification of Starch in Ionic Liquids  

Technology Transfer Automated Retrieval System (TEKTRAN)

We shall discuss the use of various ionic liquids in the preparation of starch esters. Starch was reacted with vinyl acetate in different 1-butyl-3-methylimidazolium (bmim) salts as solvents in an effort to produce starches with different acetylation patterns. Overall degree of substitution (DS) w...

385

Nanostructure of mixtures of protic ionic liquids and lithium salts: effect of alkyl chain length.  

PubMed

The bulk structure of mixtures of two protic ionic liquids, propylammonium nitrate and butylammonium nitrate, with a salt with a common anion, is analyzed at room temperature by means of small angle X-ray scattering and classical molecular dynamics simulations. The study of several structural properties, such as density, radial distribution functions, spatial distribution functions, hydrogen bonds, coordination numbers and velocity autocorrelation functions, demonstrates that increasing the alkyl chain length of the alkylammonium cation results in more segregated, better defined polar and apolar domains, the latter having a larger size. This increase, ascribed to the erosion of the H-bond network in the ionic liquid polar regions as salt is added, is confirmed by means of small angle X-ray scattering measurements, which show a clear linear increase of the characteristic spatial sizes of the studied protic ionic liquids with salt concentration, similar to that previously reported for ethylammonium nitrate (J. Phys. Chem. B, 2014, 118, 761-770). In addition, larger ionic liquid cations lead to a lower degree of hydrogen bonding and to more sparsely packed three-dimensional structures, which are more easily perturbed by the addition of lithium salts. PMID:25609558

Méndez-Morales, Trinidad; Carrete, Jesús; Rodríguez, Julio R; Cabeza, Óscar; Gallego, Luis J; Russina, Olga; Varela, Luis M

2015-02-21

386

Supercapacitors based on modified graphene electrodes with poly(ionic liquid)  

NASA Astrophysics Data System (ADS)

The improved accessibility of the electrolyte to the surface of carbon nanomaterials is a challenge to be overcome in supercapacitors based on ionic liquid electrolytes. In this study, we report the preparation of supercapacitors based on reduced graphene oxide (RGO) electrodes and ionic liquid as the electrolyte (specifically, 1-methyl-1-propylpyrrolidinium bis(trifluoromethylsulfonyl)imide or [MPPy][TFSI]). Two types of electrodes were compared: the RGO-based electrode and a poly(ionic liquid)-modified RGO electrode (PIL:RGO). The supercapacitor produced with the PIL:RGO electrode and [MPPy][TFSI] showed an electrochemical stability of 3 V and provided a capacitance of 71.5 F g-1 at room temperature; this capacitance is 130% higher with respect to the RGO-based supercapacitor. The decrease of the specific capacitance after 2000 cycles is only 10% for the PIL:RGO-based device. The results revealed the potential of the PIL:RGO material as an electrode for supercapacitors. This composite electrode increases the compatibility with the ionic liquid electrolyte compared to an RGO electrode, promoting an increase in the effective surface area of the electrode accessible to the electrolyte ions.

Trigueiro, João Paulo C.; Lavall, Rodrigo L.; Silva, Glaura G.

2014-06-01

387

Determination of local effects for chloroaluminate ionic liquids on Diels-Alder reactions.  

PubMed

Room temperature ionic liquids are an exciting class of solvents that have the potential to accelerate and control a vast range of reactions. The Diels-Alder reaction, paradigm in organic synthesis, highlights the advantages provided by ionic liquids as the reaction between cyclopentadiene and methyl acrylate in 1-ethyl-3-methylimidazolium tetrachloroaluminate and heptachlorodialuminate [EMIM][AlCl(4)] and [EMIM][Al(2)Cl(7)], respectively, has been reported to react with rates over 200 times faster and endo selectivity 10 times greater than commonly used reaction conditions. Density functional theory (DFT) calculations at the B3LYP/6-311+G(2d,p) theory level have been employed to determine the origin of the reported rate accelerations. The DFT simulations find that specific hydrogen bonding between the ionic liquid cations and the dienophile at the transition state is primarily responsible, however, the rate of reaction was found to be moderated by the solvent's hydrogen bond accepting ability (anion effect). Different anion-to-cation ratios were tested and a 1:1 ratio was determined to give the best agreement with experimental observations. The computed DFT activation barriers were within reasonable agreement of the reported rates, however it is clear that a full microenvironment featuring hundreds of ions is necessary for proper computational treatment of the solvent effects delivered by the ionic liquids. PMID:19419891

Acevedo, Orlando

2009-09-01

388

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)

2011-05-12

389

Functionalized imidazolium ionic liquids as electrolyte components of lithium batteries  

Microsoft Academic Search

Some basic properties and compatibility toward lithium electrode for electrolytes based on substituted imidazolium ionic liquid have been investigated. The ionic liquids having imidazolium cation substituted by methylcarboxyl or cyano group suffers from low conductivity. However, reversible lithium deposition–dissolution process was observed in electrolytes based on these electrolytes. In particular, lithium salt solution in cyanomethyl-substituted imidazolium ionic liquid provided similar

Minato Egashira; Hirotaka Todo; Nobuko Yoshimoto; Masayuki Morita; Jun-Ichi Yamaki

2007-01-01

390

Purification of imidazolium ionic liquids for spectroscopic applications  

Microsoft Academic Search

Ionic liquids are often contaminated by colored impurities. These impurities can be problematic for spectroscopic studies or for monitoring organic reactions by UV\\/Vis spectroscopy. The effect of different purification methods on the optical quality of colored ionic liquids was studied and compared. Yellowish ionic liquids can partially be decolorized by treatment with active charcoal or by recrystallization. Our experiments show

Peter Nockemann; Koen Binnemans; Kris Driesen

2005-01-01

391

Hypergolic Ionic Liquids DOI: 10.1002/anie.201101247  

E-print Network

Hypergolic Ionic Liquids DOI: 10.1002/anie.201101247 Generation of Melamine Polymer Condensates upon Hypergolic Ignition of Dicyanamide Ionic Liquids** Konstantin Chingin, Richard H. Perry, Steven D costs and safety require- ments associated with handling hydrazine.[2] Ionic liquids (ILs)[3] have

Zare, Richard N.

392

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

2011-01-01

393

Chiral Ionic Liquids: Synthesis, Properties, and Enantiomeric Recognition  

E-print Network

Chiral Ionic Liquids: Synthesis, Properties, and Enantiomeric Recognition Shaofang Yu, Sergey of structurally novel chiral ionic liquids which have a either chiral cation, chiral anion, or both. Cations and achiral cation toward another chiral molecule such as a quinine derivative. Introduction Ionic liquids

Reid, Scott A.

394

Electrospray from an Ionic Liquid Ferrofluid utilizing the Rosensweig Instability  

E-print Network

Electrospray from an Ionic Liquid Ferrofluid utilizing the Rosensweig Instability Edmond J. Meyer Technological University. This thruster utilized an ionic liquid ferrofluid that was synthesized by suspending magnetic nanoparticles in an ionic liquid carrier solution so that the resulting fluid is superparamagnetic

King, Lyon B.

395

Ionic Liquid Catalyzed the Internal Redox Esterification Reaction  

Microsoft Academic Search

The internal redox esterification of ?, ?-unsaturated aldehydes and alcohols was carried out using different ionic liquids (ILs) as catalysts and reaction solvent. The basic ionic liquid, 1-butyl-3-methylimidazolium acetate ([bmim]OAc) exhibited highest activity for this reaction among them. The influences of the amount of ionic liquid catalyst, and reaction time on yield of saturated ester have been investigated subsequently. The

Yinyin Yu; Li Hua; Wenwen Zhu; Yu Shi; Ting Cao; Yunxiang Qiao; Zhenshan Hou

2012-01-01

396

Ultrafast vibrational dynamics and energy transfer in imidazolium ionic liquids.  

PubMed

Femtosecond time-resolved coherent anti-Stokes Raman scattering (CARS) is used as a probe for monitoring the vibrational dynamics of room temperature ionic liquids (ILs). The experiments are performed on a series of 1,3-dialkylimidazolium ILs containing the bis(trifluoromethylsulfonyl)imide [NTf2] anion. The effect of methylation of the cationic C2 position on the dephasing time is studied analyzing [NTf2]-ILs of 1-ethyl-3-methylimidazolium [EMIM], 1-ethyl-2,3-dimethylimidazolium [EMMIM], 1-butyl-3-methylimidazolium [BMIM], and 1-butyl-2,3-dimethylimidazolium [BMMIM]. Raman coherences are excited around ?1400 cm(-1), and the vibrational dephasing of the modes in the fingerprint region is monitored as a function of time. The results indicate that vibrational energy transfer occurs governed by the interionic interactions. This is suggested by mode beating involving vibrations beyond the excitation spectrum as well as systematic differences in the temporal dephasing behavior. In contrast, the length of the cationic alkyl side chain has a negligible impact on the vibrational dynamics. PMID:24697246

Namboodiri, Mahesh; Kazemi, Mehdi Mohammad; Zeb Khan, Tahir; Materny, Arnulf; Kiefer, Johannes

2014-04-23

397

Interfacial Ionic Liquids: Connecting Static and Dynamic Structures  

E-print Network

It is well-known that room temperature ionic liquids (RTILs) often adopt a charge-separated layered structure, i.e., with alternating cation- and anion-rich layers, at electrified interfaces. However, the dynamic response of the layered structure to temporal variations in applied potential is not well understood. We used in situ, real-time X-ray reflectivity (XR) to study the potential-dependent electric double layer (EDL) structure of an imidazolium-based RTIL on charged epitaxial graphene during potential cycling as a function of temperature. The results suggest that the graphene-RTIL interfacial structure is bistable in which the EDL structure at any intermediate potential can be described by the combination of two extreme-potential structures whose proportions vary depending on the polarity and magnitude of the applied potential. This picture is supported by the EDL structures obtained by fully atomistic molecular dynamics (MD) simulations at various static potentials. The potential-driven transition between the two structures is characterized by an increasing width but with an approximately fixed hysteresis magnitude as a function of temperature. The results are consistent with the coexistence of distinct anion and cation adsorbed structures separated by an energy barrier (~0.15 eV).

Ahmet Uysal; Hua Zhou; Guang Feng; Sang Soo Lee; Song Li; Peter T. Cummings; Pasquale F. Fulvio; Sheng Dai; John K. McDonough; Yury Gogotsi; Paul Fenter

2014-12-06

398

Interfacial ionicliquids’: connecting static and dynamic structures  

NASA Astrophysics Data System (ADS)

It is well known that room temperature ionic liquids (RTILs) often adopt a charge-separated layered structure, i.e. with alternating cation- and anion-rich layers, at electrified interfaces. However, the dynamic response of the layered structure to temporal variations in applied potential is not well understood. We used in situ, real-time x-ray reflectivity to study the potential-dependent electric double layer (EDL) structure of an imidazolium-based RTIL on charged epitaxial graphene during potential cycling as a function of temperature. The results suggest that the graphene–RTIL interfacial structure is bistable in which the EDL structure at any intermediate potential can be described by the combination of two extreme-potential structures whose proportions vary depending on the polarity and magnitude of the applied potential. This picture is supported by the EDL structures obtained by fully atomistic molecular dynamics simulations at various static potentials. The potential-driven transition between the two structures is characterized by an increasing width but with an approximately fixed hysteresis magnitude as a function of temperature. The results are consistent with the coexistence of distinct anion- and cation-adsorbed structures separated by an energy barrier (˜0.15 eV).

Uysal, Ahmet; Zhou, Hua; Feng, Guang; Lee, Sang Soo; Li, Song; Cummings, Peter T.; Fulvio, Pasquale F.; Dai, Sheng; McDonough, John K.; Gogotsi, Yury; Fenter, Paul

2015-01-01

399

Ionic liquids in refinery desulfurization: comparison between biphasic and supported ionic liquid phase suspension processes.  

PubMed

The desulfurization of fuel compounds in the presence of ionic liquids is reported. For this purpose, the desulfurization efficiency of a variety of imidazolium phosphate ionic liquids has been tested. Dibenzothiophene/dodecane and butylmercaptan/decane mixtures were used as model systems. Single-stage extractions reduced the sulfur content from 500 ppm to 200 ppm. In multistage extractions the sulfur content could be lowered to less than 10 ppm within seven stages. Regeneration of the ionic liquid was achieved by distillation or re-extraction procedures. Supported ionic liquid phase (SILP) materials, obtained by dispersing the ionic liquid as a thin film on highly porous silica, exhibited a significantly higher extraction performance owing to their larger surface areas, reducing the sulfur content to less than 100 ppm in one stage. Multistage extraction with these SILP materials reduced the sulfur level to 50 ppm in the second stage. The SILP technology offers very efficient utilization of ionic liquids and circumvents mass transport limitations because of the small film thickness and large surface area, and allows application of the simple packed-bed column extraction technique. PMID:19798713

Kuhlmann, Esther; Haumann, Marco; Jess, Andreas; Seeberger, Andreas; Wasserscheid, Peter

2009-01-01

400

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

2014-02-01

401

CHARACTERIZATION AND COMPARISON OF HYDROPHILIC AND HYDROPHOBIC ROOM TEMPERATURE IONIC LIQUIDS INCORPORATING THE IMIDAZOLIUM CATION. (R828257)  

EPA Science Inventory

The perspectives, information and conclusions conveyed in research project abstracts, progress reports, final reports, journal abstracts and journal publications convey the viewpoints of the principal investigator and may not represent the views and policies of ORD and EPA. Concl...

402

Influence of the binder types on the electrochemical characteristics of natural graphite electrode in room-temperature ionic liquid  

Microsoft Academic Search

To improve the electrochemical characteristics of the natural graphite (NG-3) negative electrode in the LiCl saturated AlCl3-1-ethyl-3-methylimizadolium chloride+thionyl chloride (SOCl2) melt as the electrolyte for non-flammable lithium-ion batteries, we examined the influence of the binder types on its electrochemical characteristics. The cyclic voltammograms showed that the reduction current at 1.2–3.2V vs. Li\\/Li(I) was repressed using polyacrylic acid (PAA) as the

Koichi Ui; Jun Towada; Sho Agatsuma; Naoaki Kumagai; Keigo Yamamoto; Hiroshi Haruyama; Ken Takeuchi; Nobuyuki Koura

2011-01-01

403

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

2010-04-15

404

Phase behavior of ionic liquid crystals  

NASA Astrophysics Data System (ADS)

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.

Kondrat, S.; Bier, M.; Harnau, L.

2010-05-01

405

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: s.tsuzuki@aist.go.jp [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)

2013-11-07

406

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

2011-12-31

407

Probing the importance of ionic liquid structure: a general ionic liquid effect on an S(N)Ar process.  

PubMed

The effect of a range of ionic liquids, with systematic variations in the cation and anion, on the rate constant of an aromatic substitution process was investigated. Temperature-dependent kinetic data allowed calculation of activation parameters for the process in each solvent. These data demonstrate a generalised ionic liquid effect, with an increase in rate constant observed in each ionic solvent, though the microscopic origins of the rate constant enhancement differ with the nature of the ionic liquid. PMID:24088815

Tanner, Eden E L; Hawker, Rebecca R; Yau, Hon Man; Croft, Anna K; Harper, Jason B

2013-11-21

408

Dissolution enthalpies of cellulose in ionic liquids.  

PubMed

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

2014-11-26

409

Research on the Synthesis of Aromatic Hydrazone in Ionic Liquids  

Microsoft Academic Search

Aromatic hydrazones are important intermediates for pesticides cibenzoline and cefxime. The methodology of synthesis of aromatic hydrazone from aromatic ketone and hydrazine hydrate in ionic liquid, was described and various aromatic hydrazones were prepared by the reaction of aromatic ketone with hydrazine hydrate in ionic 1iquid at 100 °C with good yields. The ionic liquids could be recycled and reused after

Haibin Wang; Li Sun; Xiaonian Li; Jiangli Duan; Wen Pei

2011-01-01

410

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.

2011-01-01

411

Wetting and tribological properties of ionic liquids.  

PubMed

A phenomenological study of the surface-wetting and tribological properties of various ionic liquids was conducted using molecular dynamics simulations. The surface-wetting capabilities of the liquids were studied by simulating the morphological transformation of an isolated liquid drop in vacuum to its equilibrium state on solid surface. The tribological properties of the liquids were probed examining their flow behaviors and viscosities in computational lubrication experiments. All liquids exhibited good surface-wetting properties, as demonstrated by the hemispherical shape of the droplets at equilibrium and the surface contact angles. Contact angles for all liquids were much lower than 90°. Lubrication experiments demonstrated a flow behavior for the liquids that depended on the magnitude of the applied shear rate. Three distinctive flow regimes were observed: Newtonian, thixotropic (non-Newtonian), and oversheared. The liquids' viscosities were determined in the Newtonian regime and agree well with experimental results and with previously reported values calculated using equilibrium simulations. The phenomenological approach implemented in this study allowed for the calculation of the transport properties of the liquids and produced values within the appropriate order of magnitude without the use of calculational artifacts. These results corroborate previous reports indicating that nonequilibrium techniques represent a more robust approach for the calculation of transport properties than do equilibrium methods based on time-correlation functions. PMID:24641326

Castejón, Henry J; Wynn, Troy J; Marcin, Zachary M

2014-04-01

412

Corneal storage at room temperature.  

PubMed

Short-term eye banking is based mainly on moist chamber and McCarey-Kaufman medium (M-K medium) preservation. Both involve a controlled 4 C temperature for storage. Warming the cornea to room temperature, however, drastically affects the endothelial viability. On enzymatic staining and histological study, the M-K medium-stored rabbit corneas had more normal endothelium than did "moist chamber" eyes when storage was prolonged for seven days at room temperature. In human corneas that were kept at 4 C for 24 hours and then exposed to a temperature of 25 C, destruction of organelles had occurred by six hours and was increased by 12 hours. Corneas that were kept in M-K medium had relatively intact endothelium after four days, but cell disruption and vacuolation was present by the seventh day. The M-K medium, therefore, affords protection to tissue warmed to room temperature, where metabolic activity is resumed. PMID:350203

Sachs, U; Goldman, K; Valenti, J; Kaufman, H E

1978-06-01

413

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

PubMed

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

2013-01-01

414

Anharmonicity and Fragility of Protic Ionic Liquids  

NASA Astrophysics Data System (ADS)

Supercooled liquids are often characterized by their fragility which is associated with physicochemical properties. However, the origin of fragility is still controversial. Superfragile liquid, decahydroisoquinoline (DHiQ) is chosen as a parent molecule to systematically investigate the relationship between anharmonicity and fragility of supercooled liquids. Earlier study by Ueno et al. (J. Phys. Chem. B 2012, 116) demonstrated that the protonation of DHiQ by different Bronsted acids results in the loss of superfragility. To understand the nature of fragile liquids, we conducted inelastic/quasielastic (IE/QE) neutron scattering measurements to examine low frequency vibrational dynamics (boson peak) and the relaxation behavior of DHiQ (high fragility) and DHiQ-based ionic liquids with intermediate (formate, Fm) and low (trifluoromethansulfonimide, TFSI) fragilities. With the protonation, molecular acids will be hydrogen-deficient and the scattering will be dominated by cation, [DHiQ^+]. This strategy simplifies our interpretation in terms of understanding the fitting result from IENS/QENS spectra. By protonating DHiQ with stronger acids, large shift in low frequency vibrational modes and smaller mean square displacements were examined at temperatures higher than Tg. We illustrate how the degree of protonation and ionicity plays a role in the loss in superfragility of DHiQ.

Kim, Jenny; Angell, Austen; Ueno, Kazuhide; Tyagi, Madhu; Soles, Christopher; Masser, Kevin

2013-03-01

415

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)

2012-10-01

416

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

2011-01-01

417

Maleimide-modified phosphonium ionic liquids: a template towards (multi)task-specific ionic liquids.  

PubMed

The synthesis and characterization of several compounds representing a new class of multitask-specific phosphonium ionic liquids that contain a maleimide functionality is reported. The maleimide moiety of the ionic liquid (IL) is shown to undergo Michael-type additions with substrates containing either a thiol or amine moiety, thus, serving as a template to introduce wide structural diversity into the IL. Multitask-specific ILs are accessible by reaction of the maleimide with Michael donors that are capable of serving some function. As a model example to illustrate this concept, a redox active ferrocenyl thiol was incorporated and examined by cyclic voltammetry. Because the maleimide moiety is highly reactive to additions, the task-specific ionic liquids (TSILs) are prepared as the furan-protected Diels-Alder maleimide. The maleimide moiety can then be liberated when required by simple heating. PMID:20572165

Tindale, Jocelyn J; Hartlen, Kurtis D; Alizadeh, Abdolhamid; Workentin, Mark S; Ragogna, Paul J

2010-08-01

418

Chelated orthoborate ionic liquid as a reactant for the synthesis of a new cobalt borophosphate containing extra-large 16-ring channels.  

PubMed

1-Ethyl-3-methylimidazolium bis(oxalato)borate ([Emim][BOB]), a room-temperature ionic liquid, has been prepared and used for the first time to develop new borate-containing material. A new open-framework cobalt borophosphate, (NH(4))(7)Co(4)(H(2)O)[B(2)P(4)O(15)(OH)(2)](2)[H(2)PO(4)][HPO(4)], with peanut shaped extra-large 16-ring channels has been obtained. PMID:20830394

Yang, Miao; Xu, Feifei; Liu, Qingshan; Yan, Peifang; Liu, Xiumei; Wang, Chang; Welz-Biermann, Urs

2010-11-28

419

Diffusion and structure in complex fluids: I. Axial diffusion in membranes II. Proteins in ionic liquids  

NASA Astrophysics Data System (ADS)

Geometrically hindered motions of a single large solute (particle or polymer) can be imaged in real time via optical microscopy. The dynamics of fluorescent colloidal particles near surfaces and in porous membranes were monitored using confocal microscopy. A method of analysis to estimate diffusivity of particles in the axial direction by observing their intensity fluctuations was developed. The intensity fluctuations correspond to the Brownian motion of the particles in the axial direction. The method was successful in capturing the hindered diffusion of particles close to surfaces and in pores. This study provides a novel route to monitor the dynamics of particles, including biomacromolecules, near surfaces, through porous substrates and biological tissues. Ionic liquid (IL) as a medium for room temperature preservation of biomacromolecules has been proposed and, to investigate the possibility, physicochemical and enzymatic properties of proteins in the neat hydrophilic IL, ethylmethyl imidazolium ethyl sulfate [EMIM][EtSO4] were studied. Spectroscopic techniques were employed to probe the secondary and tertiary structure of proteins whereas light scattering and viscometry were used to estimate the hydrodynamic size. The secondary structure of the protein was retained in the ionic liquid but the tertiary structure was found to change. Alterations in protein conformation/activity were investigated after transfer of the dissolved protein from the IL to buffer. Further, suitability of ionic liquid gels as protein encapsulation and preservation media was assessed.

Bihari, Malvika

420

Pressure effect on vibrational frequency and dephasing of 1-alkyl-3-methylimidazolium hexafluorophosphate ionic liquids  

NASA Astrophysics Data System (ADS)

Raman spectra in the range of the totally symmetric stretching mode of the [PF6]- anion, ?s(PF6), have been measured for 1-alkyl-3-methylimidazolium ionic liquids [CnC1im][PF6], for n = 4, 6, and 8, as a function of pressure at room temperature. The ionic liquids [C6C1im][PF6] and [C8C1im][PF6] remain in an amorphous phase up to 3.5 GPa, in contrast to [C4C1im][PF6], which crystallizes above ˜0.5 GPa. Equations of state based either on a group contribution model or Carnahan-Starling-van der Waals model have been used to estimate the densities of the ionic liquids at high pressures. The shifts of the vibrational frequency of ?s(PF6) with density observed in [C6C1im][PF6] and in [C8C1im][PF6] have been calculated by a hard-sphere model of a pseudo-diatomic solute under short-range repulsive interactions with the neighboring particles. The stochastic model of Kubo for vibrational dephasing has been used to obtain the amplitude of vibrational frequency fluctuation, ???2?, and the relaxation time of frequency fluctuation, ?c, as a function of density by Raman band shape analysis of the ?s(PF6) mode of [C6C1im][PF6] and [C8C1im][PF6].

Pison, L.; Costa Gomes, M. F.; Pádua, A. A. H.; Andrault, D.; Norman, S.; Hardacre, C.; Ribeiro, M. C. C.

2013-08-01

421

SUPPLEMENTARY INFORMATION Double layer in ionic liquids: Overscreening vs. crowding  

E-print Network

SUPPLEMENTARY INFORMATION Double layer in ionic liquids: Overscreening vs. crowding Martin Z the relationship between D and E = -. To model the field energy in an ionic liquid, we assume linear dielectric energy cost for adding a charge in the bulk liquid volume V or qs on the metal surface S is, Gel = V dr

Bazant, Martin Z.

422

Application of ionic liquids as solvents for polymerization processes  

Microsoft Academic Search

Ionic liquids are organic salts that are liquid at ambient temperatures. They are non-volatile, highly polar solvents that dissolve several organic, inorganic and metaloorganic compounds. Although there is an increasing number of reports dealing with the application of ionic liquids as solvents for organic synthesis, their use in polymer synthesis is still limited. In the last few years, however, it

Przemyslaw Kubisa

2004-01-01

423

Oxidative enzymes possess catalytic activity in systems with ionic liquids  

Microsoft Academic Search

Oxidative enzymes, laccase C from Trametes sp. and horseradish and soybean peroxidases, catalyzed oxidation reactions in systems with ionic liquids whose content varied from several volume percent to almost total non-aqueous ionic liquids. Similar to the effects produced by standard organic solvents used in non-aqueous enzymology, catalytic activity of the enzymes was decreased by adding a water-miscible ionic liquid, 4-methyl-N-butylpyridinium

Glen Hinckley; Vadim V. Mozhaev; Cheryl Budde; Yuri L. Khmelnitsky

2002-01-01

424

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)

2011-04-14

425

Electrotunable Lubricity with Ionic Liquid Nanoscale Films  

NASA Astrophysics Data System (ADS)

One of the main challenges in tribology is finding the way for an in situ control of friction without changing the lubricant. One of the ways for such control is via the application of electric fields. In this respect a promising new class of lubricants is ionic liquids, which are solvent-free electrolytes, and their properties should be most strongly affected by applied voltage. Based on a minimal physical model, our study elucidates the connection between the voltage effect on the structure of the ionic liquid layers and their lubricating properties. It reveals two mechanisms of variation of the friction force with the surface charge density, consistent with recent AFM measurements, namely via the (i) charge effect on normal and in-plane ordering in the film and (ii) swapping between anion and cation layers at the surfaces. We formulate conditions that would warrant low friction coefficients and prevent wear by resisting ``squeezing-out'' of the liquid under compression. These results give a background for controllable variation of friction.

Fajardo, O. Y.; Bresme, F.; Kornyshev, A. A.; Urbakh, M.

2015-01-01

426

Electrotunable Lubricity with Ionic Liquid Nanoscale Films  

PubMed Central

One of the main challenges in tribology is finding the way for an in situ control of friction without changing the lubricant. One of the ways for such control is via the application of electric fields. In this respect a promising new class of lubricants is ionic liquids, which are solvent-free electrolytes, and their properties should be most strongly affected by applied voltage. Based on a minimal physical model, our study elucidates the connection between the voltage effect on the structure of the ionic liquid layers and their lubricating properties. It reveals two mechanisms of variation of the friction force with the surface charge density, consistent with recent AFM measurements, namely via the (i) charge effect on normal and in-plane ordering in the film and (ii) swapping between anion and cation layers at the surfaces. We formulate conditions that would warrant low friction coefficients and prevent wear by resisting “squeezing-out” of the liquid under compression. These results give a background for controllable variation of friction. PMID:25572127

Fajardo, O. Y.; Bresme, F.; Kornyshev, A. A.; Urbakh, M.

2015-01-01

427

Electrotunable lubricity with ionic liquid nanoscale films.  

PubMed

One of the main challenges in tribology is finding the way for an in situ control of friction without changing the lubricant. One of the ways for such control is via the application of electric fields. In this respect a promising new class of lubricants is ionic liquids, which are solvent-free electrolytes, and their properties should be most strongly affected by applied voltage. Based on a minimal physical model, our study elucidates the connection between the voltage effect on the structure of the ionic liquid layers and their lubricating properties. It reveals two mechanisms of variation of the friction force with the surface charge density, consistent with recent AFM measurements, namely via the (i) charge effect on normal and in-plane ordering in the film and (ii) swapping between anion and cation layers at the surfaces. We formulate conditions that would warrant low friction coefficients and prevent wear by resisting "squeezing-out" of the liquid under compression. These results give a background for controllable variation of friction. PMID:25572127

Fajardo, O Y; Bresme, F; Kornyshev, A A; Urbakh, M

2015-01-01

428

Lipid extraction from microalgae using a single ionic liquid  

DOEpatents

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

2013-05-28

429

Ionic Liquids and Ionizing Radiation: Reactivity of Highly Energetic Species  

SciTech Connect

Due to their unique properties, ionic liquids present many opportunities for basic research on the interactions of radiation with materials under conditions not previously available. At the same time, there are practical applied reasons for characterizing, understanding, and being able to predict how ionic-liquid-based devices and industrial-scale systems will perform under conditions of extreme reactivity, including radiation. This perspective discusses current issues in ionic liquid physical chemistry, provides a brief introduction to radiation chemistry, draws attention to some key findings in ionic liquid radiation chemistry, and identifies some current hot topics and new opportunities.

Wishart, J.F.

2010-11-04

430

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

2013-06-01

431

Durable electrooptic devices comprising ionic liquids  

DOEpatents

Electrolyte solutions for electrochromic devices such as rear view mirrors and displays with low leakage currents are prepared using inexpensive, low conductivity conductors. Preferred electrolytes include bifunctional redox dyes and molten salt solvents with enhanced stability toward ultraviolet radiation. The solvents include lithium or quaternary ammonium cations, and perfluorinated sulfonylimide anions selected from trifluoromethylsulfonate (CF3SO3-), bis(trifluoromethylsulfonyl)imide ((CF3SO2)2N-), bis(perfluoroethylsulfonyl)imide ((CF3CF2SO2)2N-) and tris(trifluoromethylsulfonyl)methide ((CF3SO2)3C-). Electroluminescent, electrochromic and photoelectrochromic devices with nanostructured electrodes include ionic liquids with bifunctional redox dyes.

Agrawal, Anoop (Tucson, AZ); Cronin, John P. (Tucson, AZ); Tonazzi, Juan C. L. (Tucson, AZ); Warner, Benjamin P. (Los Alamos, NM); McCleskey, T. Mark (Los Alamos, NM); Burrell, Anthony K. (Los Alamos, NM)

2005-11-01

432

Ionic liquid assisted electrospinning of quantum dots/elastomer composite Jiahua Zhu a  

E-print Network

Ionic liquid assisted electrospinning of quantum dots/elastomer composite nanofibers Jiahua Zhu wt%) of ionic liquid. Without ionic liquid, polymer solution underwent an electrospraying process between ionic liquid and the polymer chains, which well explains the function of the ionic liquid

Guo, John Zhanhu

433

Nonlinear capacitance and electrochemical behavior of ionic liquid-ionic polymer transducers  

NASA Astrophysics Data System (ADS)

Ionic polymer transducers (IPTs) are soft sensors and actuators which operate through a coupling of micro-scale chemical, electrical, and mechanical interactions. The use of an ionic liquid as solvent for an IPT has been shown to dramatically increase transducer lifetime in free-air use, while also allowing for higher applied voltages without electrolysis. In this work we model charge transport in an ionic liquid IPT by considering both the cation and anion of the ionic liquid as mobile charge carriers, a phenomenon which is unique to ionic liquid IPTs compared to their water-based counterparts. The electrochemical behavior of the large ionic liquid ions is described through a modification of the Nernst-Planck equation given by Kornyshev which accounts for steric effects in double layer packing. The method of matched asymptotic expansions is applied to solve the resulting system of equations, and analytical expressions are derived for the nonlinear charge transferred and capacitance of the IPT as a function of the applied voltage. The influence of the fraction of mobile ionic liquid ions and steric effects on the capacitance of an ionic liquid IPT is shown and compared to water-based IPTs. These results show the fundamental charge transport differences between water-based and ionic liquid IPTs and give considerations for future transducer development.

Davidson, Jacob D.; Goulbourne, N. C.

2010-04-01

434

Radiation stability of cations in ionic liquids. 4. Task-specific antioxidant cations for nuclear separations and photolithography.  

PubMed

Three families of "task-specific" antioxidant organic cations that include designated sites to facilitate deprotonation following electronic excitation and ionization have been introduced. The deprotonation from the excited state is reversible, leading to minimal damage of the cation, whereas the deprotonation from the oxidized cation yields persistent aroxyl and trityl radicals. This protection improves radiation stability of ionic compounds in 2.5 MeV electron beam radiolysis. Apart from the use of such cations as structural components of room temperature ionic liquid (IL) diluents for nuclear separations, their ionic compounds involving bases of superacids are well suited for use as chemically amplified acid generator resists in electron beam lithography and extreme ultraviolet photolithography. PMID:24245685

Shkrob, Ilya A; Marin, Timothy W

2013-11-27

435

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

2011-01-01

436

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

2014-09-01