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1

Room-Temperature Ionic Liquids for Electrochemical Capacitors  

NASA Technical Reports Server (NTRS)

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

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

2009-01-01

2

Electrochemical study of dialcarb "distillable" room-temperature ionic liquids.  

PubMed

Electrode-dependent potential windows (see picture, GC=glassy carbon) are determined for five dialkylammonium carbamate (dialcarb) room-temperature ionic liquids in a systematic study of their physical and electrochemical properties. The viscosity and conductivity of the dialcarb ionic liquids, which are "distillable" at low temperature, are comparable to those of some conventional room-temperature ionic liquids. The physical and electrochemical properties of five "distillable" room-temperature ionic liquids from the dialcarb family (dialkylammonium carbamates formed from CO(2) and dialkyl amines) are systematically investigated. In particular dimethyl (DIMCARB), diethyl (DIECARB), dipropyl (DIPCARB), methylethyl (MEETCARB), and methylpropyl (MEPRCARB) carbamate ionic liquids are studied. The temperature dependence of the viscosity and conductivity of MEETCARB exhibit an Arrhenius-type relationship. Except for DIPCARB, which has too high a resistance, a reference potential scale is available by using the IUPAC recommended redox system, that is the cobalticenium/cobaltocene (Cc(+)/Cc) process, which exhibits an ideal reversible voltammetric response. Oxidation of decamethylferrocene, but not ferrocene, also is ideal in DIMCARB, DIECARB, MEETCARB, and MEPRCARB. The magnitudes of the potential windows of the electrochemically viable dialcarbs are investigated and follow the order of glassy carbon>Au>Pt>Hg. Diffusion coefficients of Cc(+), DmFc, and double-layer capacitance values are compared in each dialcarb. Despite the considerable viscosity of the dialcarbs, steady-state voltammetric behavior is achieved at a rotating disk electrode for rotation rates of 1000 rpm or higher. PMID:19090511

Wang, Huan; Zhao, Chuan; Bhatt, Anand I; MacFarlane, Douglas R; Lu, Jia-Xing; Bond, Alan M

2009-02-01

3

Room temperature ionic liquid as a novel medium for liquid\\/liquid extraction of metal ions  

Microsoft Academic Search

Room temperature ionic liquids (RTILs) have been used as novel solvents to replace traditional volatile organic solvents in organic synthesis, solvent extraction, and electrochemistry. The hydrophobic character and water immiscibility of certain ionic liquids allow their use in solvent extraction of hydrophobic compounds. In this work, a typical room temperature ionic liquid, 1-butyl-3-methylimidazolium hexafluorophosphate [C4mim][PF6], was used as an alternative

Guor-Tzo Wei; Zusing Yang; Chao-Jung Chen

2003-01-01

4

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

5

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

6

Quinones electrochemistry in room-temperature ionic liquids.  

PubMed

The two-step electrochemical reduction of tetrachloro-1,2-benzoquinone (chloranil), 2-methyl-1,2-benzoquinone (toluquinone), and 9,10-anthraquinone in two room-temperature ionic liquids is addressed by means of voltammetry on a platinum electrode. For the subsequent quinone/radical anion (Q/Q(•-)) and radical anion/dianion (Q(•-)/Q(2-)) redox reactions, the experimental data on formal potentials in 1-butyl-3-methylimidazolium tetrafluoroborate ([C(4)mim][BF(4)]) and 1-butyl-3-methylimidazolium hexafluorophosphate ([C(4)mim][PF(6)]) and literature data for the same reactants in various aprotic molecular solvents are considered in the framework of a common potential sequence (Fc(+)/Fc scale) and compared with solvation energies computed at various levels. For the Q/Q(•-) couple, the agreement appeared to be satisfactory when solvation is described at the polarized continuum model (PCM) level. In contrast, for the Q(•-)/Q(2-) couple, the account for specific solvation at the molecular level is crucial. PMID:21155587

Nikitina, Viktoriya A; Nazmutdinov, Renat R; Tsirlina, Galina A

2011-02-01

7

Mesophases in nearly 2D room-temperature ionic liquids.  

PubMed

Computer simulations of (i) a [C(12)mim][Tf(2)N] 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, as well as relatively long aliphatic chains are strictly required for the mesophase formation, as confirmed by computations for two related systems made of (ii) the same [C(12)mim][Tf(2)N] adsorbed at a neutral solid surface and (iii) a shorter-chain RTIL ([C(4)mim][Tf(2)N]) 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. PMID:19886615

Manini, N; Cesaratto, M; Del Pópolo, M G; Ballone, P

2009-11-26

8

Behavior of electrogenerated bases in room-temperature ionic liquids.  

PubMed

The reductive electrochemistry of substituted benzophenones in the aprotic room-temperature ionic liquid (RTIL) 1-butyl-1-methylpyrrolidinium bistriflimide occurs via two consecutive one-electron processes leading to the radical anion and dianion, respectively. The radical anion exhibited electrochemical reversibility at all time-scales whereas the dianion exhibited reversibility at potential sweep rates of >or=10 V s(-1), collectively indicating the absence of strong ion-paring with the RTIL cation. In contrast, reduction in 1-butyl-3-methylimidazolium bistriflimide is complicated by proton-transfer from the [Bmim] cation. At low potential sweep rates, reduction involves a single two-electron process characteristic of either an electrochemical, chemical, electrochemical (ECE) or disproportion-type (DISP1) mechanism. The rate of radical anion protonation in [Bmim] is governed by basicity and conforms to the Hammett free-energy relation. At higher potential sweep rates in [Bmim][NTf2], reduction occurs via two consecutive one-electron processes, giving rise to the partially reversible generation of the radical anion and the irreversible generation of the dianion, respectively. Also, the redox potentials for the reversible parent/radical anion couples were found to be a linear function of Hammett substituent constants in both RTIL media and exhibited effectively equivalent solvent-dependent reaction constants, which are similar to those for reduction in polar molecular solvents such as acetonitrile or alcohols. PMID:17630791

O'Toole, Sarah; Pentlavalli, Sreekanth; Doherty, Andrew P

2007-08-01

9

Fluorescence characteristics of bisphenol A in room temperature ionic liquids.  

PubMed

Room temperature ionic liquids (RTILs) are emerging as a new class of 'green' solvents for use in a wide range of chemical processes. RTILs can sensitize or quench fluorescence of organic chemicals and their interactions still remain unclear, especially for weakly fluorescent chemicals. Herein, we report the effects of six RTILs on the fluorescence behavior of bisphenol A (BPA). The fluorescence intensities (FIs) of BPA in a RTIL-acetonitrile system were significantly quenched compared to acetonitrile. The quenching effect was stronger for [CnMIM]BF4 than [CnMIM]PF6. A decreasing trend of fluorescence lifetime (FL) of BPA was observed for [C6MIM]PF6 (4.26 to 3.86 ns) and [C14MIM]PF6 (4.15 to 3.78 ns) with increasing RTIL concentrations in the range of 1-10 mM. The quenching mode was consistent with a static quenching mechanism based on the consistency of FL and FI results. The emission bands of BPA and RTILs did not interfere with each other when RTILs were used as the solvent. The investigated RTILs enhanced the FIs of strongly fluorescing chemicals (12.0?~?19.0-fold for norfloxacin and 6.1?~?8.5-fold for dansyl chloride), but quenched those of weakly fluorescing chemicals (BPA). These results demonstrate that RTILs have different fluorescent effects on organic chemicals with different fluorophores. The interactions between RTILs and BPA result from many factors in addition to viscosity, such as solvent electrostatic dielectric constant, refractive index, density, polarization and molecular interaction. These results provide a theoretical foundation for application of RTILs in the analysis of weakly fluorescing chemical. PMID:23842893

Wang, Huili; Zou, Yujie; Li, Changli; Wang, Wenwei; Zhang, Minghua; Dahlgren, Randy A; Wang, Xuedong

2013-11-01

10

Determination of an acidic scale in room temperature ionic liquids.  

PubMed

The acidity scale of different Brønsted acids in ionic liquids such as [BMIM][NTf2], [BMIM][BF4], and [BMMIM][BF4] has been investigated by determination of Hammett functions, using a spectrophotometric indicator method. This scale should permit one to correlate the acidity strength of ionic liquid systems with their ability to achieve acid-catalyzed reactions. PMID:12720424

Thomazeau, Cécile; Olivier-Bourbigou, Hélène; Magna, Lionel; Luts, Stéphane; Gilbert, Bernard

2003-05-01

11

LIQUID\\/LIQUID EXTRACTION OF METAL IONS IN ROOM TEMPERATURE IONIC LIQUIDS  

Microsoft Academic Search

The search for more environmentally-friendly reaction media has prompted the development of a wide array of alternative systems that will sustain biphasic separations with aqueous solutions without the use of volatile organic compounds (VOCs). We have begun to employ Room Temperature Ionic Liquids (RTIL), specifically 1-alkyl-3-methylimidazolium hexafluorophosphate ([Cnmim][PF6]), as VOC replacements in liquid\\/liquid separations of metal ions from aqueous solutions.

Ann E. Visser; Richard P. Swatloski; Scott T. Griffin; Deborah H. Hartman; Robin D. Rogers

2001-01-01

12

Applications of room temperature ionic liquids in interfacial polymerization  

NASA Astrophysics Data System (ADS)

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

Zhu, Lining

13

Potential Applications of Room Temperature Ionic Liquids for Fission Products and Actinide Separation  

Microsoft Academic Search

Room temperature ionic liquids (RTILs) are receiving increased attention for possible applications in nuclear fuel cycle. RTILs are being investigated as possible substitutes to molecular diluents in solvent extraction, and as an alternative to high temperature molten salts in non-aqueous reprocessing applications. It is well recognized that ionic liquids often display unique extraction behavior. Unusual extraction of various metal ions

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

2011-01-01

14

Potential Applications of Room Temperature Ionic Liquids for Fission Products and Actinide Separation  

Microsoft Academic Search

Room temperature ionic liquids (RTILs) are receiving increased attention for possible applications in nuclear fuel cycle. RTILs are being investigated as possible substitutes to molecular diluents in solvent extraction, and as an alternative to high temperature molten salts in non-aqueous reprocessing applications. It is well recognized that ionic liquids often display unique extraction behavior. Unusual extraction of various metal ions

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

2012-01-01

15

Room-temperature phosphonium ionic liquids for supercapacitor application  

NASA Astrophysics Data System (ADS)

Ionic liquids (ILs) have been used as electrolytes for supercapacitors. Two phosphonium salts such as trihexyl(tetradecyl)phosphonium bis(trifluoromethylsulfonyl)imide (IL1) and trihexyl(tetradecyl) phosphonium dicyanamide (IL2) have been selected for this target. To decrease the viscosity of ILs, a small amount of acetonitrile (from 5 to 25 wt %) was added. Supercapacitor based on activated carbon (AC) as electrodes and IL1 with 25 wt % of acetonitrile supplied capacitance values of 100 F/g at a high operating voltage of 3.4 V. Such a supercapacitor reached a high energy of ~40 Wh/kg and a good cyclability.

Frackowiak, Elzbieta; Lota, Grzegorz; Pernak, Juliusz

2005-04-01

16

Characterisation and application of carbon film electrodes in room temperature ionic liquid media  

Microsoft Academic Search

Carbon film electrodes have been characterised in the room temperature ionic liquids, 1-butyl-3-methylimidazolium bis(trifluoromethane)sulfonimide (BmimNTF2), 1-butyl-1-methylpyrrolidinium bis(trifluoromethane)sulfonimide, (BpyrNTF2) and 1-butyl-3-methylimidazolium nitrate (BmimNO3), by cyclic voltammetry and electrochemical impedance spectroscopy. The electrochemical behaviour of the ionic liquids depended on both cation and anion of these electrolytes. Oxygen reduction is clearly visible at carbon film electrodes – after oxygen removal the potential

Rasa Pauliukaite; Andrew P. Doherty; Kevin D. Murnaghan; Christopher M. A. Brett

2008-01-01

17

Ordering of Triblock Copolymer Surfactants by Blending with a Room Temperature Ionic Liquid  

NASA Astrophysics Data System (ADS)

Well-ordered block copolymer microdomains were obtained by blending Pluronic PEO-PPO-PEO triblock copolymer surfactants with the room temperature ionic liquid, 1-butyl-3-methylimidazolium hexafluorophosphate. The selective association of the ionic liquid with the PEO blocks increases the segregation strength by increasing the effective interaction parameter between the blocks. The neat copolymer is phase-mixed in the melt whereas the addition of ionic liquid to the copolymer results in phase segregation, forming well-ordered microdomains. The ionic liquid was confirmed to interact with the PEO blocks by a depression in the melting point of the blends with increasing ionic liquid concentration. Further, small angle x-ray scattering experiments show a decrease in the breadth of the first order peak, as well as the appearance of higher order peaks, with increasing ionic liquid concentration. These results confirm the formation of well-ordered microdomains.

Miranda, Daniel; Watkins, James; Russell, Thomas

2009-03-01

18

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

19

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

Microsoft Academic Search

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.

Jing-Fang Huang; Gary A. Baker; Huimin Luo; Kunlun Hong; Qing-Feng Li; Niels J. Bjerrum; Sheng Dai

2006-01-01

20

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

21

Glycosylation in room temperature ionic liquid using unprotected and unactivated donors.  

PubMed

Glycosylation in room temperature ionic liquid is demonstrated using unprotected and unactivated donors. Modest yields of simple benzyl glycosides and disaccharides of glucose, mannose and N-acetylgalactosamine were obtained in 1-ethyl-3-methylimidazolium benzoate with Amberlite IR-120 (H(+)) resin or p-toluenesulfonic acid as promoters. PMID:17173880

Park, Tae-Joon; Weïwer, Michel; Yuan, Xuejun; Baytas, Sultan N; Munoz, Eva M; Murugesan, Saravanababu; Linhardt, Robert J

2007-02-26

22

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

23

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

PubMed

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 the determination of gas-liquid partition coefficients and activity coefficients as well as thermodynamic constants derived from either of these parameters and their variation with temperature. The solvation parameter model can be used to define the contribution from individual intermolecular interactions to the gas-liquid partition coefficient. Application of chemometric procedures to a large database of system constants for ionic liquids indicates their unique solvent properties: low cohesion for ionic liquids with weakly associated ions compared with non-ionic liquids of similar polarity; greater hydrogen-bond basicity than typical polar non-ionic solvents; and a range of dipolarity/polarizability that encompasses the same range as occupied by the most polar non-ionic liquids. These properties can be crudely related to ion structures but further work is required to develop a comprehensive approach for the design of ionic liquids for specific applications. Data for liquid-liquid partition coefficients is scarce by comparison with gas-liquid partition coefficients. Preliminary studies indicate the possibility of using the solvation parameter model for interpretation of liquid-liquid partition coefficients determined by shake-flask procedures as well as the feasibility of using liquid-liquid chromatography for the convenient and rapid determination of liquid-liquid partition coefficients. Spectroscopic measurements of solvatochromic and fluorescent probe molecules in room temperature ionic liquids provide insights into solvent intermolecular interactions although interpretation of the different and generally uncorrelated "polarity" scales is sometimes ambiguous. All evidence points to the ionic liquids as a unique class of polar solvents suitable for technical development. In terms of designer solvents, however, further work is needed to fill the gaps in our knowledge of the relationship between ion structures and physicochemical properties. PMID:15214660

Poole, Colin F

2004-05-28

24

Influence of water on the surface of hydrophilic and hydrophobic room-temperature ionic liquids.  

PubMed

Vibrational spectroscopy, sum frequency generation, has been used to study the gas-liquid interface of imidazolium-based, room-temperature ionic liquids. The ionic liquids are divided into two categories on the basis of their miscibility with water, as hydrophobic (immiscible) and hydrophilic (miscible). The spectroscopy results indicate that water will reorient the cations of the hydrophobic ionic liquid, while in the hydrophilic ones they remain unaffected. Thus, under low water conditions the plane of the imidazolium ring remains parallel to the surface for both types of ionic liquid. However, at high water content the ring will reorient to along the surface normal for the hydrophobic ionic liquid but remain parallel to the surface for the hydrophilic one. This is a reversible process. PMID:15382902

Rivera-Rubero, Selimar; Baldelli, Steven

2004-09-29

25

Ab initio simulations of thermal decomposition and of electron transfer reactions in room temperature ionic liquids.  

PubMed

Selected aspects of the ab initio modelling of room temperature ionic liquids are discussed in our contribution, focusing on thermal decomposition reactions, and on the determination of the electrochemical stability window of these compounds. In both cases, we emphasise the role of ab initio simulation methods, able to deal simultaneously with the ionic and electronic side of the systems and phenomena under investigation. PMID:22455031

Ballone, Pietro; Cortes-Huerto, Robinson

2012-01-01

26

Synthesis and characterization of ionic polymer networks in a room-temperature ionic liquid.  

PubMed

Ionic liquid gels (ILGs) for potential use in ion transport and separation applications were generated via a free radical copolymerization of 2-acrylamido-2-methyl-1-propanesulfonic acid (AMPS) and N,N'-methylene(bis)acrylamide (MBA) using 1-ethyl-3-methylimidazolium ethylsulfate (IL) as a room temperature ionic liquid solvent medium. The AMPS and MBA monomer solubility window in the IL in the temperature range of 25 to 65 °C was determined. In situ ATR-FTIR showed near complete conversion of monomers to a cross-linked polymer network. ILGs with glass transition temperatures (T(g)s) near -50 °C were generated with T(g) decreasing with increasing IL content. The elastic moduli in compression (200 to 6600 kPa) decreased with increasing IL content and increasing AMPS content while the conductivities (0.35 to 2.14 mS cm?¹) increased with increasing IL content and decreasing MBA content. The polymer-IL interaction parameter (?) (0.48 to 0.55) was determined via a modified version of the Bray and Merrill equation. PMID:23088450

Stanzione, Joseph F; Jensen, Robert E; Costanzo, Philip J; Palmese, Giuseppe R

2012-11-01

27

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

28

Probing anion–carbon dioxide interactions in room temperature ionic liquids: Gas phase cluster calculations  

Microsoft Academic Search

The interaction of a CO2 molecule with different anions commonly used in room temperature ionic liquids (RTILs) has been studied under isolated conditions. Minimum energy structures obtained using density functional theory based calculations suggest the dominance of Lewis acid–base interactions between the species. In the optimized configurations, the CO2 molecule is found to adopt a non-linear geometry. The extent of

B. L. Bhargava; S. Balasubramanian

2007-01-01

29

Solubility and diffusivity of 1,1,1,2-tetrafluoroethane in room-temperature ionic liquids  

Microsoft Academic Search

The solubility and diffusivity of 1,1,1,2-tetrafluoroethane (R-134a) in seven room-temperature ionic liquids (RTILs) are presented. Among them, five of the RTILs were prepared for the first time with three new fluorocarbon sulfonate anions, and two were commercially available (1-butyl-3-methylimidazolium hexafluorophosphate was previously studied with R-134a). The gas absorption measurements were made using a gravimetric microbalance. Four isotherms (283.15, 298.15, 323.15,

Mark B. Shiflett; Mark A. Harmer; Christopher P. Junk; A. Yokozeki

2006-01-01

30

Improving electrochemical properties of room temperature ionic liquid (RTIL) based electrolyte for Li-ion batteries  

Microsoft Academic Search

Room temperature ionic liquids (RTILs) with high safety characteristic usually have high viscosity and melting point, which is adverse for the application of RTIL-based electrolytes in Li-ion batteries. In this investigation, a promising RTIL, i.e. PP13TFSI consisting of N-methyl-N-propylpiperidinium (PP13) cation and bis(trifluoromethanesulfonyl)imide (TFSI) anion is synthesized. The effect of the content of Li salt in the electrolytes containing PP13TFSI

H. F. Xiang; B. Yin; H. Wang; H. W. Lin; X. W. Ge; S. Xie; C. H. Chen

2010-01-01

31

Investigation of the anodic behavior of Al current collector in room temperature ionic liquid electrolytes  

Microsoft Academic Search

We have investigated the anodic behaviors of aluminum as a cathodic current collector for lithium ion batteries in several kinds of room temperature ionic liquids (RTILs) and EC+DMC solutions containing LiN(CF3SO2)2 by cyclic voltammetry (CV), chronoamperometry (CA), scanning electron microscopy (SEM), energy dispersive X-ray (EDX) spectroscopy and X-ray photoelectron spectroscopy (XPS). Cyclic voltammetry and chronoamperometry data showed that the current

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

2008-01-01

32

Ordering of Triblock Copolymer Surfactants by Blending with a Room Temperature Ionic Liquid  

NASA Astrophysics Data System (ADS)

Well-ordered block copolymer morphologies were obtained by blending Pluronic PEO-PPO-PEO triblock copolymer surfactants with the room temperature ionic liquid 1-butyl-3-methylimidazolium hexafluorophosphate. The selective association of the ionic liquid with the PEO blocks raises the effective interaction parameter between the PEO and PPO blocks. Therefore, the copolymer/ionic liquid blends form well-ordered microdomains in the melt, whereas the neat copolymers are phase mixed in the melt. The ionic liquid was confirmed to interact with the PEO chains by a depression in the melting point of the PEO crystals with increasing ionic liquid concentration. Wide angle x-ray scattering and polarized optical microscopy also indicate disruption of PEO crystallization in the blends. Infrared spectroscopy also indicates a strong interaction between the PEO blocks and ionic liquid. The formation of well-ordered microdomains is demonstrated by small angle x-ray scattering experiments, which show the appearance of higher order peaks with increasing ionic liquid concentration.

Miranda, Daniel; Watkins, James; Russell, Thomas

2010-03-01

33

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

34

Polymer electrolytes based on room temperature ionic liquid: 2,3-dimethyl-1-octylimidazolium triflate.  

PubMed

Room temperature ionic liquid (DMOImTf) based upon 2,3-dimethyl-1-octylimidazolium cation and trifluoromethanesulfonate or triflate (CF(3)SO(3))(-) anion has been synthesized and shows conductivity of 5.68 mS/cm and viscosity of 26.4 cP at 25 degrees C. Ion conducting polymer electrolytes based on polymers (poly(ethylene oxide) (PEO) and polyvinylidenefluoride-co-hexafluoropropylene (PVdF-HFP)) and ionic liquid (DMOImTf) were prepared in film form by the casting technique. The conductivity of polymer electrolytes containing 0.5 M LiCF(3)SO(3) in PEO:DMOImTf taken in equal weight ratio increases with the addition of propylene carbonate (PC) while its mechanical stability improved by dispersing nanosize fumed silica. However, polymer electrolytes containing PVdF-HFP and ionic liquid show a high value of conductivity (10(-4)-10(-3) S/cm) alongwith better mechanical stability. PMID:16853102

Singh, Boor; Sekhon, S S

2005-09-01

35

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

36

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

37

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

PubMed Central

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

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

2012-01-01

38

SEM observation of hydrous superabsorbent polymer pretreated with room-temperature ionic liquids.  

PubMed

Room-temperature ionic liquid (RTIL), which is a liquid salt at or below room temperature, shows peculiar physicochemical properties such as negligible vapor pressure and relatively-high ionic conductivity. In this investigation, we used six types of RTILs as a liquid material in the pretreatment process for scanning electron microscope (SEM) observation of hydrous superabsorbent polymer (SAP) particles. Very clear SEM images of the hydrous SAP particles were obtained if the neat RTILs were used for the pretreatment process. Of them, tri-n-butylmethylphosphonium dimethylphosphate ([P(4, 4, 4, 1)][DMP]) provided the best result. On the other hand, the surface morphology of the hydrous SAP particles pretreated with 1-ethyl-3-methylimidazolium tetrafluoroborate ([C2mim][BF4]) and 1-butyl-3-methylimidazolium tetrafluoroborate ([C4mim][BF4]) was damaged. The results of SEM observation and thermogravimetry analysis of the hydrous SAP pretreated with the RTILs strongly suggested that most water in the SAP particles are replaced with RTIL during the pretreatment process. PMID:24621609

Tsuda, Tetsuya; Mochizuki, Eiko; Kishida, Shoko; Iwasaki, Kazuki; Tsunashima, Katsuhiko; Kuwabata, Susumu

2014-01-01

39

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

SciTech Connect

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

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

2003-01-01

40

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

SciTech Connect

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

Hussey, Charles L.

2005-06-01

41

Translation-rotation decoupling and nonexponentiality in room temperature ionic liquids  

NASA Astrophysics Data System (ADS)

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

Griffin, Philip; Agapov, Alexander; Sokolov, Alexei

2013-03-01

42

Translation-rotation decoupling and nonexponentiality in room temperature ionic liquids  

NASA Astrophysics Data System (ADS)

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, Philip J.; Agapov, Alexander L.; Sokolov, Alexei P.

2012-08-01

43

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

PubMed

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, [C(2)mim]CF(3)SO(3)) 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 [C(2)mim]CF(3)SO(3), indicating that the quasilattice of [C(2)mim]CF(3)SO(3) is somewhat disorganized. The potential ability to spectroscopically characterize the structure of the quasilattice, which governs the long-range ion-ion interactions in a RTIL, is a major step forward in understanding the interrelationship between the molecular-level interactions among the constituent ions of an ionic liquid and the important physical properties of the RTIL. PMID:21476760

Burba, Christopher M; Frech, Roger

2011-04-01

44

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

PubMed Central

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

Burba, Christopher M.; Frech, Roger

2011-01-01

45

Determination of the physical properties of room temperature ionic liquids using a Love wave device.  

PubMed

In this work, we have shown that a 100 MHz Love wave device can be used to determine whether room temperature ionic liquids (RTILs) are Newtonian fluids and have developed a technique that allows the determination of the density-viscosity product, ??, of a Newtonian RTIL. In addition, a test for a Newtonian response was established by relating the phase change to insertion loss change. Five concentrations of a water-miscible RTIL and seven pure RTILs were measured. The changes in phase and insertion loss were found to vary linearly with the square root of the density-viscosity product for values up to (??)(1/2) ~ 10 kg m(-2) s(-1/2). The square root of the density-viscosity product was deduced from the changes in either phase or insertion loss using glycerol as a calibration liquid. In both cases, the deduced values of ?? agree well with those measured using viscosity and density meters. Miniaturization of the device, beyond that achievable with the lower-frequency quartz crystal microbalance approach, to measure smaller volumes is possible. The ability to fabricate Love wave and other surface acoustic wave sensors using planar metallization technologies gives potential for future integration into lab-on-a-chip analytical systems for characterizing ionic liquids. PMID:21786814

Ouali, F Fouzia; Doy, Nicola; McHale, Glen; Hardacre, Christopher; Ge, Rile; Allen, Ray W K; MacInnes, Jordan M; Newton, Michael I

2011-09-01

46

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

47

Electrodeposition of metallic uranium at near ambient conditions from room temperature ionic liquid  

NASA Astrophysics Data System (ADS)

The electrochemical behavior of U(IV) in the room temperature ionic liquid (RTIL), N-methyl-N-propylpiperidinium bis(trifluoromethylsulfonyl)imide (MPPiNTf 2), was investigated to evaluate the feasibility of using the RTIL for non-aqueous reprocessing application. In this context, the rate of dissolution of uranium oxide (UO 2) in HNTf 2 was studied at 353 K. The dissolution of UO 2 in HNTf 2 was rapid; nearly 50% of UO 2 dissolved within 3 h and more than 95% dissolved in 25 h. The resultant solution was dried, diluted with MPPiNTf 2 and the electrochemical behavior of U(IV) in MPPiNTf 2 was studied at 373 K at platinum, glassy carbon and stainless steel electrodes. The cyclic voltammograms of U(IV) in MPPiNTf 2 at platinum and glassy carbon electrodes consisted of four cathodic waves occurring at a peak potentials of -0.7 V (Fc/Fc +), -1.4 V, -2.2 V and -2.7 V. Controlled potential electrolysis of a solution of U(IV) in MPPiNTf 2 at -2.8 V (Fc/Fc +) resulted in the deposition of metallic uranium, which was confirmed by X-ray diffraction and scanning electron microscopy.

Jagadeeswara Rao, Ch.; Venkatesan, K. A.; Nagarajan, K.; Srinivasan, T. G.; Vasudeva Rao, P. R.

2011-01-01

48

Surface tension of room temperature ionic liquids measured by dynamic light scattering.  

PubMed

Using dynamic light scattering techniques, we obtained the surface tension sigma, surface excess entropy S(sigma), surface excess enthalpy H(sigma), and viscosity eta for the following seven room temperature ionic liquids in a wide temperature range from 30 to around 140 degrees C: 1-butyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide, 1-hexyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide, N-methyl-N-propylpiperidinium bis(trifluoromethanesulfonyl)imide, N,N,N-trimethyl-N-propylammonium bis(trifluoromethanesulfonyl)imide, 1-butyl-3-methylimidazolium hexafluorophosphate, 1-hexyl-3-methylimidazolium hexafluorophosphate, and 1-octyl-3-methyl imidazolium hexafluorophosphate. We have found that sigma increases systematically with decreasing the anion size and the alkyl side chain length. On the other hand, S(sigma) and eta increase with decreasing the anion size but decrease with decreasing the alkyl chain length. H(sigma) seems to decrease with increasing the anion size, but it has no clear dependence on the alkyl chain length. We discuss the bulk and surface properties, referring to the Coulomb interactions and van der Waals interactions. PMID:19449941

Osada, R; Hoshino, T; Okada, K; Ohmasa, Y; Yao, M

2009-05-14

49

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

PubMed

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

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

2010-07-01

50

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

PubMed

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 {H(3)O(+)•CE}NO(3)(-) 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. PMID:21434622

Marin, Timothy W; Shkrob, Ilya A; Dietz, Mark L

2011-04-14

51

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

52

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

53

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

54

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

Microsoft Academic Search

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

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

2002-01-01

55

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

National Technical Information Service (NTIS)

The overall goal of this project is to develop a new ionic liquid based solvent extraction process for separation of Cs- 137 and Sr-90 from tank wastes. To synthesize new ionic liquids tailored for the extractive separation of Cs+ and Sr2+. To select opti...

H. Luo S. Dai P. V. Bonnesen A. C. Buchanan

2005-01-01

56

Antimicrobial active silver nanoparticles and silver\\/polystyrene core-shell nanoparticles prepared in room-temperature ionic liquid  

Microsoft Academic Search

Uniform silver nanoparticles and silver\\/polystyrene core-shell nanoparticles were successfully synthesized in a room temperature ionic liquid, 1-n-butyl-3-methylimidazolium tetrafluoroborate ([BMIM]·BF4). [BMIM]·BF4 plays a protective role to prevent the nanoparticles from aggregation during the preparation process. Transmission electron micrographs confirm that both silver nanoparticles and core-shell nanoparticles are regular spheres with the sizes in the range of 5–15 nm and 15–25 nm, respectively. The

Jing An; Desong Wang; Qingzhi Luo; Xiaoyan Yuan

2009-01-01

57

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

PubMed

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

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

2013-01-17

58

Differential solubility of ethylene and acetylene in room-temperature ionic liquids: a theoretical study.  

PubMed

The room-temperature ionic liquids (RTILs) have potential in realizing the ethylene (C(2)H(4)) and acetylene (C(2)H(2)) separation and avoiding solvent loss and environmental pollution compared with traditional solvents. The interaction mechanisms between gases and RTILs are important for the exploration of new RTILs for gas separation; thus, they were studied by quantum chemical calculation and molecular dynamics simulation in this work. The optimized geometries were obtained for the complexes of C(2)H(4)/C(2)H(2) with anions (Tf(2)N(-), BF(4)(-), and OAc(-)), cation (bmim(+)), and their ion pairs, and the analysis for geometry, interaction energy, natural bond orbital (NBO), and atoms in molecules (AIM) was performed. The quantum chemical calculation results show that the hydrogen-bonding interaction between the gas molecule and anion is the dominant factor in determining the solubility of C(2)H(2) in RTILs. However, the hydrogen-bonding interaction, the p-? interaction in C(2)H(4)-anion, and the ?-? interaction in C(2)H(4)-cation are weak and comparable, which all affect the solubility of C(2)H(4) in RTILs with comparable contribution. The calculated results for the distance of H(gas)···X (X = O or F in anions), the BSSE-corrected interaction energy, the electron density of H(gas)···X at the bond critical point (?(BCP)), and the relative second-order perturbation stabilization energy (E(2)) are consistent with the experimental data that C(2)H(2) is more soluble than C(2)H(4) in the same RTILs and the solubility of C(2)H(4) in RTILs has the following order: [bmim][Tf(2)N] > [bmim][OAc] > [bmim][BF(4)]. The calculated results also agree with the order of C(2)H(2) solubility in different RTILs that [bmim][OAc] > [bmim][BF(4)] > [bmim][Tf(2)N]. Furthermore, the calculation results indicate that there is strong C(2)H(2)-RTIL interaction, which cannot be negligible compared to the RTIL-RTIL interaction; thus, the regular solution theory is probably not suitable to correlate C(2)H(2) solubility in RTILs. The molecular dynamics simulation results show that the hydrogen bond between the H in C2 of the imidazolium cation and the anion will weaken the hydrogen-bonding interaction of the gas molecule and anion in a realistic solution condition, especially in the C(2)H(4)-RTIL system. PMID:22414155

Zhao, Xu; Xing, Huabin; Yang, Qiwei; Li, Rulong; Su, Baogen; Bao, Zongbi; Yang, Yiwen; Ren, Qilong

2012-04-01

59

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

60

Synthesis and electrochemical characterization of PEO-based polymer electrolytes with room temperature ionic liquids  

Microsoft Academic Search

New gel polymer electrolytes containing 1-butyl-4-methylpyridinium bis(trifluoromethanesulfonyl)imide (BMPyTFSI) ionic liquid are prepared by solution casting method. Thermal and electrochemical properties have been determined for these gel polymer electrolytes. The addition of BMPyTFSI to the P(EO)20LiTFSI electrolyte results in an increase of the ionic conductivity, and at high BMPyTFSI concentration (BMPy+\\/Li+=1.0), the ionic conductivity reaches the value of 6.9×10?4S\\/cm at 40°C.

Hu Cheng; Changbao Zhu; Bin Huang; Mi Lu; Yong Yang

2007-01-01

61

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

62

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...

63

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

64

Anion effect on radiochemical stability of room-temperature ionic liquids under gamma irradiation.  

PubMed

Radiochemical stability of imidazolium-based ionic liquids constituted of the BuMeIm(+) cation and associated with four commonly used anions (X(-): Tf(2)N(-), TfO(-), PF(6)(-) and BF(4)(-)) has been investigated under gamma irradiation for high irradiation doses (up to 2.0 MGy). The anion effect has been examined by quantifying the radiolytic yields of disappearance for cation and anions and by identifying corresponding radiolysis products with several analytical techniques. On the one hand, a large number of radiolysis products are formed throughout the irradiation in ionic liquid solutions, resulting from reactions of primary generated species of cation and anion by indirect radiolysis. Primary generated species can react together throughout the irradiation by indirect radiolysis to form numerous radiolysis products in small quantities, indicating that several complex degradation pathways are involved for these radiation doses. This degradation pattern has been confirmed by identification of numerous gaseous radiolytic products. On the other hand, quantitative studies show that radiochemical stabilities of ionic liquids are in the same range of values as systems envisioned in nuclear fuel reprocessing with relatively low hydrogen yields. Indeed, this present work emphasizes the suitability of ionic liquids for applications in the nuclear fuel cycle. PMID:20449114

Le Rouzo, G; Lamouroux, C; Dauvois, V; Dannoux, A; Legand, S; Durand, D; Moisy, P; Moutiers, G

2009-08-21

65

Anion concentration-dependent partitioning mechanism in the extraction of uranium into room-temperature ionic liquids.  

PubMed

The mode of partitioning of uranyl ion between nitrate-containing aqueous phases and various N,N'-dialkylimidazolium-based room-temperature ionic liquids (RTILs) in the presence of tri-n-butyl phosphate (TBP) is shown to change from an ion-exchange process to one involving extraction of a neutral uranyl-TBP-nitrato complex as the aqueous nitrate concentration is increased. Increasing the hydrophobicity of the RTIL cation eventually leads to nitrato complex extraction as the predominant mode of partitioning, regardless of nitrate concentration. PMID:18371927

Dietz, Mark L; Stepinski, Dominique C

2008-04-15

66

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

67

Dielectric relaxation and solvation dynamics in a room-temperature ionic liquid: temperature dependence.  

PubMed

Dielectric relaxation, related polarization and conductivity, and solvation dynamics of the ionic liquid 1-butyl-3-methylimidazolium hexafluorophosphate (BMI(+)PF6(-)) are studied via molecular dynamics computer simulations in the temperature range 300 K ? T ? 500 K. Two main bands of its dielectric loss spectrum show differing temperature behaviors. As T increases, the absorption band in the microwave region shifts to higher frequencies rapidly, whereas the location of the bimodal far-IR band remains nearly unchanged. Their respective intensities tend to decrease and increase. The static dielectric constant of BMI(+)PF6(-) is found to decrease weakly with T. The ultrafast inertial component of solvation dynamics remains largely unchanged, while their dissipative relaxation component becomes faster. Roles played by ion reorientations and translations in governing dynamic and static dielectric properties of the ionic liquid are examined. A brief comparison with available experimental results is also made. PMID:23978043

Shim, Youngseon; Kim, Hyung J

2013-10-01

68

Extraction of Azo Dyes from Aqueous Solutions with Room Temperature Ionic Liquids  

Microsoft Academic Search

In this work, ionic liquids\\/water distribution ratios (D) of azo dyes, including 1-(phenylazo)-2-naphthol, 1-(2-pyridylazo)-2-naphthol, 4-(nitrophenylazo)resorcinol, 4-(2-pyridylazo) resorcinol, and 2-(4-dimethylaminophenylazo) benzoic acid, have been determined experimentally. It was found that the D values are highly influenced by the pH of the water phase and the type of salts added. They increase with increasing alkyl chain length on the cations of the

Jing Fan; Yunchang Fan; Sheli Zhang; Jianji Wang

2011-01-01

69

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

PubMed

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

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

2014-01-30

70

Facile preparation of polysaccharide-coated capillaries using a room temperature ionic liquid for chiral separations.  

PubMed

In this study, the dissolution of polysaccharides into an ionic liquid was investigated and applied as a coating onto the capillary walls of a fused-silica capillary in open-tubular CEC. The coating was evaluated by examining the chiral separation of two analytes (thiopental, sotalol) with three cellulose derivatives (cellulose acetate, cellulose acetate phthalate, and cellulose acetate butyrate). Baseline separation of thiopental enantiomers was achieved by use of each polysaccharide coating (Rs: 7.0, 8.1, 7.1), while sotalol provided partial resolution (Rs: 0.7, 1.0, 0.9). In addition, reproducibility of the cellulose-coated capillaries was evaluated by estimating the run-to-run and capillary-to-capillary RSD values of the EOF. Both stability and reproducibility were very good with RSD values of less than 7%. PMID:23463600

Stavrou, Ioannis J; Moore, Leonard; Fernand, Vivian E; Kapnissi-Christodoulou, Constantina P; Warner, Isiah M

2013-05-01

71

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

72

Room temperature ionic liquid as matrix medium for the determination of residual solvents in pharmaceuticals by static headspace gas chromatography.  

PubMed

Using new solvent room temperature ionic liquid (IL) matrix media, testing of residual solvents in pharmaceutical preparations with static headspace gas chromatographic (SH-GC), is described. The purpose of this work was to demonstrate the feasibility of IL as diluent, six solvents utilized in synthesis of Adefovir Dipivoxil: acetonitrile, dichloromethane, N-methyl-2-pyrrolidone (NMP), toluene, dimethylformamide (DMF), n-butyl ether were dissolved in IL: 1-butyl-3-methylimidazolium tetrafluoroborate ([bmim]BF(4)). The method of external standard was used for quantitative analysis. Its performance was evaluated and validated: all the RSD were lower than 10%, the limits of detection were all of the ppm level and the method was both accurate and linear. And better sensitivities for the six solvents were gained with [bmim]BF(4) as diluent comparing with DMSO. PMID:17765909

Liu, Feng-Hua; Jiang, Ye

2007-10-01

73

Room temperature ionic liquid-mediated molecularly imprinted polymer monolith for the selective recognition of quinolones in pork samples.  

PubMed

A novel molecularly imprinted polymer monolith was prepared by the room temperature ionic liquid-mediated in situ molecular imprinting technique, using norfloxacin (NOR) as the template, methacrylic acid as the functional monomer, ethylene glycol dimethacrylate as the cross-linker. The optimal synthesis conditions and recognition properties of NOR-imprinted monolithic column were investigated. The results indicated that the imprinted monoliths exhibited good ability of selective recognition against the template and its structural analog. Using the fabricated material as solid-phase extraction sorbent, a sample pre-treatment procedure of molecularly imprinted solid-phase extraction coupling with HPLC was developed for determination of trace quinolone residues in animal tissues samples. The recoveries ranging from 78.16 to 93.50% for eight quinolones antibiotics such as marbofloxacin, NOR, ciprofloxacin, danofloxacin, difloxacin, oxolinic acid, flumequine and enrofloxacin were obtained. PMID:21082676

Sun, Xiangli; He, Jia; Cai, Guorui; Lin, Anqing; Zheng, Wenjie; Liu, Xuan; Chen, Langxing; He, Xiwen; Zhang, Yukui

2010-12-01

74

The electroreduction of benzoic acid: voltammetric observation of adsorbed hydrogen at a platinum microelectrode in room temperature ionic liquids.  

PubMed

The electrochemical reduction of benzoic acid in the presence and absence of hydrogen (H(2)) has been investigated using a 10 ?m diameter platinum microelectrode in four different room temperature ionic liquids (RTILs), namely [C(4)mim][NTf(2)], [C(4)mpyrr][NTf(2)], [C(4)mim][OTf] and [C(4)mim][BF(4)], versus Ag/Ag(+). In all cases, reductive voltammetry is observed, and is suggested to occur via a CE mechanism in which dissociation of benzoic acid is followed by electron transfer to H(+) ultimately forming adsorbed hydrogen. Furthermore, the adsorbed H atoms, formed from the reduction of benzoic acid, could be used to achieve the rapid hydrogenolysis of the organic compound (bis(benzyloxycarbonyl)-l-lysine) on the timescale of the voltammetric technique under moderate conditions (25 °C). PMID:23262562

Meng, Yao; Norman, Sarah; Hardacre, Christopher; Compton, Richard G

2013-02-14

75

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

76

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].

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

2011-01-01

77

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

78

Theoretical investigations of ferrocene/ferrocenium solvation in imidazolium-based room-temperature ionic liquids.  

PubMed

The ferrocene/ferrocenium (Fc/Fc(+)) redox couple has been deemed one of the best candidates of the standard electrochemical reference for redox reactions in ionic liquids (ILs). To fully reveal the redox reaction mechanism in the IL condensed phase, solvation, as a prerequisite, apparently needs to be understood. As a preliminary attempt to study the solvation of Fc/Fc(+) in imidazolium-based ILs, using model complexes, systematic investigations of the intrinsic pair-wise interactions between the solute and solvent ions in the gas phase are performed with B97-D, a dispersion-corrected density functional method. B97-D is carefully benchmarked with available experimental values and high-level ab initio quantum mechanical results for Fc/Fc(+) alone and the solvated structures. Present calculations demonstrate dramatically different solvation features for Fc vs. Fc(+), e.g., Fc forms direct stable interactions with both solvent cations and anions with binding energies of -11 to -14 kcal mol(-1). As an interesting observation, no ?-stacking interactions are captured between the imidazolium ring of the solvent cation and the cyclopentadienyl motif of the solute. However, due to the strong electrostatic interactions, Fc(+) can only be solvated by solvent anions in the first solvation shell with much stronger binding energies of -72 to -86 kcal mol(-1). Binding energies, structures, and electrostatic potentials are all characterized. The electronic structures are further analyzed with the Natural Bond Orbital method. The theoretical calculation results help explain several experimental observations obtained earlier or in the present work, including solubility, diffusion coefficient, and solution conductivity. Due to the involvement of the aromatic structures, the current study also sheds valuable light on ?-interactions, in general. PMID:23325150

Yang, Yang; Yu, Lei

2013-02-28

79

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

PubMed

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

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

2006-11-01

80

Orientation correlation of sulfosuccinate-based room-temperature ionic liquids studied by polarization-resolved hyper-Rayleigh scattering.  

PubMed

Hyper-Rayleigh scattering (HRS) of sulfosuccinate-based room-temperature ionic liquids (RTILs), tetraalkylammonium salts of bis(2-ethylhexyl)sulfosuccinate (BEHSS(-)) and di(isobutyl)sulfosuccinate (DIBSS(-)), shows strong orientation correlation between sulfosuccinate ions for both BEHSS(-)-based and DIBSS(-)-based RTILs. The hyperpolarizability and polarization resolved HRS, giving information at the dipolar electric order and at the quadrupolar electric order, respectively, have been measured as a function of the distance between sulfosuccinates by changing the size of the tetraalkylammonium ions constituting the ionic liquids. The variations obtained for the dipolar electric and quadrupolar electric components of the HRS intensity show the orientation correlation between sulfosuccinate ions. In particular, the weight parameter eta introduced for molecular assemblies deviates from a pure dipolar electric order that is generally expected for a homogeneous molecular solution. Nonmonotonic variations of eta with increasing the alkyl chain length of tetraalkylammonium ions indicate a transition in the organization of the anions from an homogeneous to an heterogeneous arrangement with increasing the intermolecular distance between sulfosuccinate ions due to the competition between the short- and long-range molecular interactions. PMID:19842644

Revillod, Guillaume; Nishi, Naoya; Kakiuchi, Takashi

2009-11-19

81

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

82

Efficient solvent system containing malonamides in room temperature ionic liquids: actinide extraction, fluorescence and radiolytic degradation studies.  

PubMed

Solvent extraction studies of actinide metal ions such as Am(III), U(VI), Np(IV), Np(VI), Pu(IV) were carried out in a nitric acid medium using two diamides (L) viz. (DMDBTDMA (N,N'-dimethyl-N,N'-dibutyl-2-tetradecylmalonamide) and DMDOHEMA (N,N'-dimethyl-N,N'-dioctyl-2-(2'-(hexyloxy)ethyl)-malonamide) dissolved in different room temperature ionic liquids (RTILs). The use of RTILs as the diluent significantly enhanced metal ion extraction as compared to that observed in non polar diluent such as n-dodecane. The effects of parameters such as kinetics, aqueous phase acidity (0.01-3 M HNO(3)), metal ion oxidation states, diamide concentration on the extraction of metal ions were studied. The stoichiometry of the extracted Am(III) species using these diamides varied with ligand concentration viz. (Am.3L)(3+) ([L] = 0.005-0.02 M) and (Am.2-2.5L)(3+) ([L] = 0.05-0.1 M). Time resolved laser induced fluorescence spectroscopy (TRLFS) studies showed that the extracted species of Eu(III) in an ionic liquid medium had no coordinated water molecules, in contrast to the presence of 1-2 water molecules in the extracted species in a n-dodecane medium. The radiolytic degradation behavior of the diamides/RTIL system has been studied using IR spectroscopy and gas chromatography-mass spectrometry (GC-MS). The data revealed that a significantly lower ligand concentration is required for actinide extraction in ionic liquids as the extraction media as compared to nonpolar diluents. PMID:23135734

Patil, Ajay B; Pathak, Priyanath; Shinde, Vaishali S; Godbole, Shrikant V; Mohapatra, Prasanta K

2013-02-01

83

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

84

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

PubMed

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. PMID:24919471

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

2014-07-16

85

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

86

Voltammetry of ion transfer across a polarized room-temperature ionic liquid membrane facilitated by valinomycin: theoretical aspects and application.  

PubMed

Cyclic voltammetry is used to investigate the transfer of alkali-metal cations, protons, and ammonium ions facilitated by the complex formation with valinomycin at the interface between an aqueous electrolyte solution and a room-temperature ionic liquid (RTIL) membrane. The membrane is made of a thin (approximately 112 microm) microporous filter impregnated with an RTIL that is composed of tridodecylmethylammonium cations and tetrakis[3,5-bis(trifluoromethyl)phenyl]borate anions. An extension of the existing theory of voltammetry of ion transfer across polarized liquid membranes makes it possible to evaluate the standard ion-transfer potentials for the hydrophilic cations studied, as well as the stability constants (K(i)) of their 1:1 complexes with valinomycin, as log K(i) = 9.0 (H(+)), 11.1 (Li(+)), 12.8 (Na(+)), 17.2 (K(+)), 15.7 (Rb(+)), 15.1 (Cs(+)), and 14.7 (NH(4)(+)). These data point to the remarkably enhanced stability of the valinomycin complexes within RTIL, and to the enhanced selectivity of valinomycin for K(+) over all other univalent ions studied, compared to the conventional K(+) ion-selective liquid-membrane electrodes. Selective complex formation allows one to resolve voltammetric responses of K(+) and Na(+) in the presence of an excess of Mg(2+) or Ca(2+), which is demonstrated by determination of K(+) and Na(+) in the table and tap water samples. PMID:19572695

Langmaier, Jan; Samec, Zdenek

2009-08-01

87

Highly reversible lithium metal secondary battery using a room temperature ionic liquid/lithium salt mixture and a surface-coated cathode active material.  

PubMed

For the purpose of realizing high-voltage, high-capacity, long-life and safe rechargeable batteries, a lithium secondary battery that uses high-voltage stable ZrO2-coated LiCoO2 cathode powder and a nonvolatile high-safety room temperature ionic liquid was fabricated. PMID:16432577

Seki, Shiro; Kobayashi, Yo; Miyashiro, Hajime; Ohno, Yasutaka; Usami, Akira; Mita, Yuichi; Watanabe, Masayoshi; Terada, Nobuyuki

2006-02-01

88

Acoustics as a tool for better characterization of ionic liquids: a comparative study of 1-alkyl-3-methylimidazolium bis[(trifluoromethyl)sulfonyl]imide room-temperature ionic liquids.  

PubMed

Acoustic properties of three (1-ethyl-, 1-butyl-, and 1-octyl-) 1-alkyl-3-methylimidazolium bis[(trifluoromethyl)sulfonyl] imide room-temperature ionic liquids are reported and discussed. The speeds of sound in RTILs were measured as a function of temperature in the range 288-323 K by means of a sing around method. The densities and isobaric heat capacities were determined from 288.15 to 363.15 K and from 293.15 to 323.15 K, respectively. The related properties, like isentropic and isothermal compressibilities, isobaric coefficients of thermal expansion, molar isochoric heat capacities, and internal pressures, were calculated. It was found that for some ionic liquids, temperature dependence of isobaric coefficients of thermal expansion is small and negative. All investigations were completed by the ultrasound absorption coefficient measurements in 1-ethyl- and 1-octyl-3-methylimidazolium bis[(trifluoromethyl)sulfonyl] imide as a function of frequency from 10 to 300 MHz at temperatures 293.15-298.15 K. The ultrasound absorption spectra indicate relaxation frequencies in the megahertz range. PMID:23510074

Zor?bski, Edward; Geppert-Rybczy?ska, Monika; Zor?bski, Micha?

2013-04-11

89

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

PubMed

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

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

2012-05-28

90

Room temperature ionic liquids as useful overlayers for estimating food quality from their odor analysis by quartz crystal microbalance measurements.  

PubMed

An array of quartz crystals coated with different room-temperature ionic liquids (RTILs) is proposed for the analysis of flavors by quartz crystal microbalance (QCM) measurements. Seven RTILs were adopted as sensing layers, all containing imidazolium or phosphonium cations, differing from one another in the length and branching of alkyl groups and neutralized by different anions. The array was at first applied to the analysis of 31 volatile organic compounds (VOCs), such as alcohols, phenols, aldehydes, esters, ketones, acids, amines, hydrocarbons and terpenes, chosen as representative components of a wide variety of food flavors. Multivariate data analysis by the principal component analysis (PCA) approach of the set of the corresponding responses led to separated clusters for these different chemical categories. To further prove the good performance of the RTIL-coated quartz crystal array as an "electronic nose", it was applied to the analysis of headspaces from cinnamon samples belonging to different botanical varieties ( Cinnamon zeylanicum and Cinnamon cassia ). PCA applied to responses recorded on different stocks of samples of both varieties showed that they could be fully discriminated. PMID:23808811

Toniolo, Rosanna; Pizzariello, Andrea; Dossi, Nicolò; Lorenzon, Stefano; Abollino, Ornella; Bontempelli, Gino

2013-08-01

91

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

PubMed

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

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

2012-06-30

92

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

PubMed

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. PMID:24685901

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

2014-07-15

93

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

94

The observation of dianions generated by electrochemical reduction of trans-stilbenes in ionic liquids at room temperature.  

PubMed

Three highly aprotic bis(trifluoromethylsulfonyl)amide (NTf2(-)) based ionic liquids (ILs) containing the cations trihexyl(tetradecyl)phosphonium (P6,6,6,14(+)), N-butyl-N-methylpyrrolidinium (Pyrr4,1(+)), and (trimethylamine)(dimethylethylammine)dihydroborate ((N111)(N112)BH2(+)) have been examined as media for room temperature voltammetric detection of highly basic stilbene dianions electrochemically generated by the reduction of trans-stilbene (t-Stb) and its derivatives (4-methoxy-, 2-methoxy-, 4,4'-dimethyl-, and 4-chloromethyl-). Transient and steady-state data in the ILs were compared with results obtained in the molecular solvent acetonitrile. In all media examined, the t-Stb(0/•-) process is chemically and electrochemically reversible with a heterogeneous charge transfer rate constant in CH3CN of 1.5 cm s(-1), as determined by Fourier transformed AC voltammetry. However, further reduction to the dianion was always irreversible in this molecular but weakly acidic solvent. On the other hand, a substantial level of chemical reversibility for the reduction of t-Stb(•-) to t-Stb(2-) on the time scale of cyclic voltammetry is achieved when the concentration of trans-stilbene, [t-Stb], appreciably exceeds the concentration of adventitious water or other proton sources. In particular, these conditions are met when [t-Stb] ? 0.1 M in thoroughly dehydrated and purified ILs, while in the presence of CH3CN, t-Stb(2-) still suffers fast irreversible protonation under these stilbene concentration conditions. The E0/•-(0) values (vs Fc(0/+)) for substituted trans-stilbenes in acetonitrile and (N111)(N112)BH2-NTf2 do not differ substantially, nor do the E0/•-(0) and E•-/2-(0) differences or other aspects of the voltammetric behavior. PMID:23659207

Abdul-Rahim, Omar; Simonov, Alexandr N; Rüther, Thomas; Boas, John F; Torriero, Angel A J; Collins, David J; Perlmutter, Patrick; Bond, Alan M

2013-06-18

95

Direct electron transfer of cytochrome c and its biosensor based on gold nanoparticles\\/room temperature ionic liquid\\/carbon nanotubes composite film  

Microsoft Academic Search

A robust and effective composite film based on gold nanoparticles (GNPs)\\/room temperature ionic liquid (RTIL)\\/multi-wall carbon nanotubes (MWNTs) modified glassy carbon (GC) electrode was prepared by a layer-by-layer self-assembly technique. Cytochrome c (Cyt c) was successfully immobilized on the RTIL-nanohybrid film modified GC electrode by electrostatic adsorption. Direct electrochemistry and electrocatalysis of Cyt c were investigated. The results suggested that

Cuili Xiang; Yongjin Zou; Li-Xian Sun; Fen Xu

2008-01-01

96

Theoretical and spectroscopic studies of 1-butyl-3-methylimidazolium iodide room temperature ionic liquid: Its differences with chloride and bromide derivatives  

Microsoft Academic Search

1-Butyl-3-methylimidazolium iodide (bmimI) a room temperature ionic liquid (RTIL), widely used as nonvolatile electrolyte solution in dye-sensitized photoelectrochemical cells has been synthesised and its UV–Visible and Infrared (IR) spectroscopic studies were performed. The spectral features were characterized by Density Functional Theory (DFT) calculation at B3LYP level using DGDZVP basis sets. Time-Dependent-DFT (TD-DFT) calculation on this RTIL was done at the

Madhulata Shukla; Nitin Srivastava; Satyen Saha

2010-01-01

97

Synergistic enhancement effect of room temperature ionic liquids for cloud point extraction combined with UV-vis spectrophotometric determination nickel in environmental samples  

NASA Astrophysics Data System (ADS)

A new method based on enhancement effect of room temperature ionic liquids for cloud point extraction trace amounts of nickel combined with UV-vis spectrophotometric determination was developed. Room temperature ionic liquids (RTILs) and diethyldithiocarbamate (DDTC) were used enhancement reagent and chelating reagent, respectively. The addition of room temperature ionic liquids leads to 3.0 times improvement in the determination of nickel. The nonionic surfactant Triton X-100 was used as the extractant. When the temperature of the system was higher than the cloud point of Triton X-100, Ni-DTC complex was extracted into Triton X-100 and separation of the analyte from the matrix was achieved. Some parameters that influenced cloud point extraction and subsequent determination were evaluated in detail, such as the concentrations of RTILs, DDTC and Triton X-100; pH of sample solution, as well as interferences. Under optimized conditions, an enrichment factor of 72 could be obtained, and the detection limit (LOD) for Ni was 0.5 ng mL-1. Relative standard deviations for five replicate determinations of the standard solution containing 50 ng mL-1 Ni was 3.9%. The proposed method was successfully applied to the determination of nickel in certified reference materials with satisfactory results.

Zeng, Chujie; Xu, Xili; Zhou, Neng; Lin, Yao

98

Synergistic enhancement effect of room temperature ionic liquids for cloud point extraction combined with UV-vis spectrophotometric determination nickel in environmental samples.  

PubMed

A new method based on enhancement effect of room temperature ionic liquids for cloud point extraction trace amounts of nickel combined with UV-vis spectrophotometric determination was developed. Room temperature ionic liquids (RTILs) and diethyldithiocarbamate (DDTC) were used enhancement reagent and chelating reagent, respectively. The addition of room temperature ionic liquids leads to 3.0 times improvement in the determination of nickel. The nonionic surfactant Triton X-100 was used as the extractant. When the temperature of the system was higher than the cloud point of Triton X-100, Ni-DTC complex was extracted into Triton X-100 and separation of the analyte from the matrix was achieved. Some parameters that influenced cloud point extraction and subsequent determination were evaluated in detail, such as the concentrations of RTILs, DDTC and Triton X-100; pH of sample solution, as well as interferences. Under optimized conditions, an enrichment factor of 72 could be obtained, and the detection limit (LOD) for Ni was 0.5ng mL(-1). Relative standard deviations for five replicate determinations of the standard solution containing 50ng mL(-1) Ni was 3.9%. The proposed method was successfully applied to the determination of nickel in certified reference materials with satisfactory results. PMID:22503873

Zeng, Chujie; Xu, Xili; Zhou, Neng; Lin, Yao

2012-08-01

99

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.

100

Novel Fission-Product Separation Based on Room-Temperature Ionic Liquids. (Report for September 15, 2001-September 14, 2004).  

National Technical Information Service (NTIS)

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 seco...

2004-01-01

101

A new strategy for synthesis of novel classes of room-temperature ionic liquids based on complexation reaction of cations  

Microsoft Academic Search

A novel series of ionic liquids have been synthesized with a new methodology. The essence of this methodology is to form the cations of ionic liquids through the complexation reactions of neutral organic ligands with metal ions, followed by the subsequent metathesis reactions of the resulting salts with anion donors. We chose N-lithiotrifluoromethanesulfonimide (Li{sup +} TfN) as a candidate for

Jing-Fang Huang; Huimin Luo; Sheng Dai

2006-01-01

102

Instability of actinide(IV) hexachloro complexes in room-temperature ionic liquid [BuMeIm]PF 6 due to hydrolysis of the hexafluorophosphate anion  

Microsoft Academic Search

Visible\\/NIR spectrophotometry, solid-state NMR and spectroscopy reveal the hydrolysis of the PF6? anion in the room-temperature ionic liquid [BuMeIm]PF6, where BuMeIm+ is 1-butyl-3-methylimidazolium, in the presence of water and AnCl62?, where An(IV) is Th(IV), Np(IV), and Pu(IV). Slow absorption spectra evolution of AnCl62? solutions is finished by solid products' precipitation. Solids are attributed to the mixture of An(IV) phosphates and

Sergey I. Nikitenko; Claude Berthon; Philippe Moisy

2007-01-01

103

Solvent and rotational relaxation of Coumarin-153 in a micellar solution of a room-temperature ionic liquid, 1-butyl-3-methylimidazolium octyl sulfate, in ethylammonium nitrate  

NASA Astrophysics Data System (ADS)

We have investigated the micelle formation by room-temperature ionic liquid (RTIL), 1-butyl-3-methylimidazolium octyl sulfate (bmimOs) with another RTIL, ethyl ammonium nitrate (EAN). In addition, the effect of micelle formation on the solvation and rotational relaxation dynamics have been observed using steady-state and picoseconds time-resolved spectroscopy. Both the solvent and rotational relaxations of Coumarin-153 are retarded in the micelle compared to that of neat EAN. The increase in average solvation time on going from neat EAN to bmimOs-EAN micelle is very small compared to the increase in solvation time on going from pure water to water containing micelle.

Rao, Vishal Govind; Ghatak, Chiranjib; Pramanik, Rajib; Sarkar, Souravi; Sarkar, Nilmoni

2010-10-01

104

A Protic Ionic Liquid Catalyzes CO2 Conversion at Atmospheric Pressure and Room Temperature: Synthesis of Quinazoline-2,4(1H,3H)-diones.  

PubMed

The chemical fixation of CO2 under mild reaction conditions is of significance from a sustainable chemistry viewpoint. Herein a CO2 -reactive protic ionic liquid (PIL), [HDBU(+) ][TFE(-) ], was designed by neutralization of the superbase 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU) with a weak proton donor trifluoroethanol (TFE). As a bifunctional catalyst for simultaneously activating CO2 and the substrate, this PIL displayed excellent performance in catalyzing the reactions of CO2 with 2-aminobenzonitriles at atmospheric pressure and room temperature, thus producing a series of quinazoline-2,4(1H,3H)-diones in excellent yields. PMID:24788820

Zhao, Yanfei; Yu, Bo; Yang, Zhenzhen; Zhang, Hongye; Hao, Leiduan; Gao, Xiang; Liu, Zhimin

2014-06-01

105

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

PubMed

Lipophilicity of several novel analgesic active 1-(1-arylimidazolidyn-2-ylidyn)-3-arylalkyl urea derivatives has been estimated by the use of chromatographic method. The investigated compounds were analyzed by reversed-phase high performance liquid chromatography (RP-HPLC) using mixtures of methanol or acetonitrile and water with addition of imidazolium based room temperature ionic liquids varying in an anion chaotropicity as the mobile phases. The relationships between log k values vs. concentration of organic solvent was used for determination of the log k(w) values by extrapolation technique. The partition coefficients (log P) values were calculated by means of the Pallas 3.1.1.2. and Spartan 10.0 softwares and further correlated with log k(w) measured experimentally in classical organic-aqueous eluent system and systems modified with ionic liquids addition. It was found that log k(w) values measured in eluent system modified with butyl-methyl imidazoilum chloride correlate the best with the logarithm of partition coefficient calculated by Pallas software (log P(calc.)). Furthermore, it was found that the examined compounds form H-bonding with imidazoilum cation of modifiers improving the chromatographic peak parameters (the symmetry factor, the theoretical plates number) especially when ionic liquid's anion was more chaotropic. Amphiphilic ionic liquid possessing longer alkyl chain substituent (OMIM BF(4)) can be considered as a new cationic surfactant. Micellar conditions improved separation selectivity of chloro- and methoxy substituted derivatives. PMID:22445825

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

2012-07-01

106

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

PubMed

Quantitative prediction of physical properties of room temperature ionic liquids through nonpolarizable force field based molecular dynamics simulations is a challenging task. The challenge lies in the fact that mean ion charges in the condensed phase can be less than unity due to polarization and charge transfer effects whose magnitude cannot be fully captured through quantum chemical calculations conducted in the gas phase. The present work employed the density-derived electrostatic and chemical (DDEC/c3) charge partitioning method to calculate site charges of ions using electronic charge densities obtained from periodic density functional theory (DFT) calculations of their crystalline phases. The total ion charges obtained thus range between -0.6e for chloride and -0.8e for the PF6 ion. The mean value of the ion charges obtained from DFT calculations of an ionic liquid closely matches that obtained from the corresponding crystal thus confirming the suitability of using crystal site charges in simulations of liquids. These partial charges were deployed within the well-established force field developed by Lopes et al., and consequently, parameters of its nonbonded and torsional interactions were refined to ensure that they reproduced quantum potential energy scans for ion pairs in the gas phase. The refined force field was employed in simulations of seven ionic liquids with six different anions. Nearly quantitative agreement with experimental measurements was obtained for the density, surface tension, enthalpy of vaporization, and ion diffusion coefficients. PMID:24605817

Mondal, Anirban; Balasubramanian, Sundaram

2014-03-27

107

Protonated/deprotonated properties of a room temperature ionic liquid-water system: N, N-Diethyl-N-methyl-N-2-methoxyethyl ammonium tetrafluoroborate  

NASA Astrophysics Data System (ADS)

The pH oscillations related to the protonation/deprotonation process in a room temperature ionic liquid (RTIL)-water system were observed at fixed temperatures. The RTIL was hydrophilic N, N-diethyl-N-methyl-N-2-methoxyethyl ammonium tetrafluoroborate ([DEME][BF4]). The rhythmic oscillations of pH were observed only at a water concentration of approximately 90 mol%, where the equilibrated pH value was approximately 3. In contrast, in the water-poor region from 6 to 10 mol% H2O, the pH was almost constant at approximately 8 within the investigated timeframe. The acid-base properties of the [DEME][BF4]-water mixture are related to particular aggregations in the liquid phase.

Aono, Masami; Abe, Hiroshi; Takekiyo, Takahiro; Yoshimura, Yukihiro

2014-04-01

108

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

PubMed

In the present work, we show that the autocorrelation function of the capillary-wave displacement is expressed by the sum of the ordinary oscillator and the bulk shear-mode terms. The former is expressed by a simple damped oscillator form or a sum of exponentially damping functions depending on the extent of damping. The latter is also written by superposition of exponentially damping modes, and an analytically exact formulation is obtained. We performed surface dynamic light-scattering experiment for the surface of an ionic liquid, 1-butyl- 3-methylimidazolium bis[(trifluoromethyl)sulfonyl]imide, and compared the experimental autocorrelation function with the theoretical one. We observed for the first time the bulk shear-mode contribution, and confirmed that the experimental data is well explained by the theoretical autocorrelation function. PMID:19658509

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

2009-06-01

109

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

NASA Astrophysics Data System (ADS)

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

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

2014-05-01

110

Studies on the nuances of the electrochemically induced room temperature isomerization of cis-stilbene in acetonitrile and ionic liquids.  

PubMed

Electrochemical reduction of cis-stilbene occurs by two well-resolved one-electron reduction steps in acetonitrile with (n-Bu)4NPF6 as the supporting electrolyte and in N-butyl-N-methylpyrrolidinium (Pyrr1,4(+)) and (trimethylamine)(dimethylethylamine)-dihydroborate bis(trifluoromethylsulfonyl)amide (NTf2(-)) ionic liquids (ILs). Mechanistic details of the electroreduction have been probed by dc and Fourier transformed ac voltammetry, simulation of the voltammetry, bulk electrolysis, and EPR spectroscopy. The first one-electron reduction induces fast cis to trans isomerization in CH3CN and ILs, most likely occurring via disproportionation of cis-stilbene radical anions and fast transformation of the cis-dianion to the trans-configuration. The second reduction process is chemically irreversible in CH3CN due to protonation of the dianion but chemically reversible in highly aprotic ILs under high cis-stilbene concentration conditions. Increase of the (n-Bu)4NPF6 supporting electrolyte concentration (0.01-1.0 M) in CH3CN induces substantial positive shifts in the potentials for reduction of cis-stilbene, consistent with strong ion pairing of the anion radical and dianion with (n-Bu)4N(+). However, protection by ion pairing against protonation of the stilbene dianions or electrochemically induced cis-trans-stilbene isomerization is not achieved. Differences in electrode kinetics and reversible potentials for cis-stilbene(0/•-) and trans-stilbene(0/•-) processes are less pronounced in the Pyrr1,4-NTf2 ionic liquid than in the molecular solvent acetonitrile. PMID:24558952

Abdul-Rahim, Omar; Simonov, Alexandr N; Boas, John F; Rüther, Thomas; Collins, David J; Perlmutter, Patrick; Bond, Alan M

2014-03-20

111

Preparation of room temperature ionic liquids based on aliphatic onium cations and asymmetric amide anions and their electrochemical properties as a lithium battery electrolyte  

NASA Astrophysics Data System (ADS)

The physical and electrochemical properties of room temperature ionic liquids (RTILs) based on asymmetric amide anions (TSAC: 2,2,2-trifluoro- N-(trifluoromethylsulfonyl)acetamide, C1C2: N-(trifluoromethylsulfonyl)pentafluoroethylsulfonamide) and aliphatic onium cations, such as ammonium, phosphonium, and sulfonium, were reported. The melting point of the C1C2 salts decreased compared to the corresponding TFSI salts (TFSI: bis(trifluoromethylsulfonyl)imide), however, the viscosity was about twice that of the TFSI salts. Relatively low viscosity RTILs based on aliphatic onium cations could be prepared using the TSAC anion and tetraalkylammonium cation containing an alkoxy group. The linear sweep voltammogram of these RTILs with and without Li-TFSI were investigated in order to estimate the electrochemical windows and possible use as a lithium battery electrolyte.

Matsumoto, Hajime; Sakaebe, Hikari; Tatsumi, Kuniaki

112

Small volume laboratory on a chip measurements incorporating the quartz crystal microbalance to measure the viscosity-density product of room temperature ionic liquids  

PubMed Central

A microfluidic glass chip system incorporating a quartz crystal microbalance (QCM) to measure the square root of the viscosity-density product of room temperature ionic liquids (RTILs) is presented. The QCM covers a central recess on a glass chip, with a seal formed by tightly clamping from above outside the sensing region. The change in resonant frequency of the QCM allows for the determination of the square root viscosity-density product of RTILs to a limit of ?10 kg m?2 s?0.5. This method has reduced the sample size needed for characterization from 1.5 ml to only 30 ?l and allows the measurement to be made in an enclosed system.

Doy, N.; McHale, G.; Newton, M. I.; Hardacre, C.; Ge, R.; MacInnes, J. M.; Kuvshinov, D.; Allen, R. W.

2010-01-01

113

Assembly of CeO2-TiO2 nanoparticles prepared in room temperature ionic liquid on graphene nanosheets for photocatalytic degradation of pollutants.  

PubMed

CeO(2)-TiO(2) nanoparticles were prepared by the sol-gel process using 2-hydroxylethylammonium formate as room-temperature ionic liquid and calcined at different temperatures (500-700°C). CeO(2)-TiO(2)-graphene nanocomposites were prepared by hydrothermal reaction of graphene oxide with CeO(2)-TiO(2) nanoparticles in aqueous solution of ethanol. The photocatalysts were characterized by X-ray diffraction, BET surface area, diffuse reflectance spectroscopy, scanning electron microscopy, and Fourier transformed infrared techniques. The results demonstrate that the room-temperature ionic liquid inhibits the anatase-rutile phase transformation. This effect was promoted by addition of CeO(2) to TiO(2). The addition of graphene to CeO(2)-TiO(2) nanoparticles enhances electron transport and therefore impedes the charge recombination of excited TiO(2). The photodegradation results of the pollutants in aqueous medium under UV irradiation revealed that CeO(2)-TiO(2)-graphene nanocomposites exhibit much higher photocatalytic activity than CeO(2)-TiO(2) and pure TiO(2). The photocatalytic activity of CeO(2)-TiO(2)-graphene nanocomposites decreases with additional increasing of the graphene content. Moreover, comparison of the photocatalytic activities of CeO(2)-TiO(2)-graphene with the other CeO(2)-TiO(2)-carbon demonstrates that CeO(2)-TiO(2)-graphene nanocomposites have the highest photocatalytic activity due to their unique structure and electronic properties. Chemical oxygen demand for solutions of the pollutants gave a good idea about mineralization of them. PMID:22104082

Ghasemi, S; Setayesh, S Rahman; Habibi-Yangjeh, A; Hormozi-Nezhad, M R; Gholami, M R

2012-01-15

114

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

PubMed

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

Evans, Russell G; Compton, Richard G

2006-02-13

115

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

116

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

NASA Astrophysics Data System (ADS)

Recent three-pulse photon echo peak shift (3PEPS) measurements [M. Muramatsu, Y. Nagasawa, and H. Miyasaka, J. Phys. Chem. A 115, 3886 (2011)] with several room temperature ionic liquids (RTILs) have revealed multi-exponential dynamics with ultrafast solvation timescale in the range, 20 < ?1/fs < 250, for both imidazolium and phosphonium RTILs. This is striking for two reasons: (i) the timescale is much faster than those reported by the dynamic Stokes shift (DSS) experiments [S. Arzhantsev, H. Jin, G. A. Baker, and M. Maroncelli, J. Phys. Chem. B 111, 4978 (2007)] and (ii) sub-hundered femtosecond solvation response in phosphonium ionic liquids is reported for the first time. Here, we present a mode coupling theory based calculation where such ultrafast solvation in 3PEPS measurements has been visualized to originate from the nearest neighbour solute-solvent interaction. Consideration of Lennard-Jones interaction for the nearest neighbour solute-solvent non-dipolar interaction leads to biphasic dynamics with a predicted ultrafast time constant in the ~100-250 fs range, followed by a slower one similar to that reported by the 3PEPS measurements. In addition, the calculated fast time constants and amplitudes are found to be in general agreement with those from computer simulations. Different microscopic mechanisms for ultrafast solvation response measured by the 3PEPS and DSS experiments have been proposed and relative contributions of the collective and nearest neighbour solvent modes investigated. Relation between the single particle rotation and ultrafast polar solvation in these RTILs has been explored. Our analyses suggest 3PEPS and DSS experiments are probably sensitive to different components of the total solvation energy relaxation of a laser-excited dye in a given ionic liquid. Several predictions have also been made, which may be re-examined via suitable experiments.

Daschakraborty, Snehasis; Biswas, Ranjit

2012-09-01

117

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

PubMed

Recent three-pulse photon echo peak shift (3PEPS) measurements [M. Muramatsu, Y. Nagasawa, and H. Miyasaka, J. Phys. Chem. A 115, 3886 (2011)] with several room temperature ionic liquids (RTILs) have revealed multi-exponential dynamics with ultrafast solvation timescale in the range, 20 < ?(1)?fs < 250, for both imidazolium and phosphonium RTILs. This is striking for two reasons: (i) the timescale is much faster than those reported by the dynamic Stokes shift (DSS) experiments [S. Arzhantsev, H. Jin, G. A. Baker, and M. Maroncelli, J. Phys. Chem. B 111, 4978 (2007)] and (ii) sub-hundered femtosecond solvation response in phosphonium ionic liquids is reported for the first time. Here, we present a mode coupling theory based calculation where such ultrafast solvation in 3PEPS measurements has been visualized to originate from the nearest neighbour solute-solvent interaction. Consideration of Lennard-Jones interaction for the nearest neighbour solute-solvent non-dipolar interaction leads to biphasic dynamics with a predicted ultrafast time constant in the ?100-250 fs range, followed by a slower one similar to that reported by the 3PEPS measurements. In addition, the calculated fast time constants and amplitudes are found to be in general agreement with those from computer simulations. Different microscopic mechanisms for ultrafast solvation response measured by the 3PEPS and DSS experiments have been proposed and relative contributions of the collective and nearest neighbour solvent modes investigated. Relation between the single particle rotation and ultrafast polar solvation in these RTILs has been explored. Our analyses suggest 3PEPS and DSS experiments are probably sensitive to different components of the total solvation energy relaxation of a laser-excited dye in a given ionic liquid. Several predictions have also been made, which may be re-examined via suitable experiments. PMID:22998265

Daschakraborty, Snehasis; Biswas, Ranjit

2012-09-21

118

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.

119

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

120

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

121

Deciphering the interaction of a model transport protein with a prototypical imidazolium room temperature ionic liquid: effect on the conformation and activity of the protein.  

PubMed

The present contribution reports the interaction of a prototypical surface-active room temperature ionic liquid (RTIL) viz., 1-butyl-3-methylimidazolium tetrafluoroborate ([BMIM][BF4]) with a globular transport protein bovine serum albumin (BSA). The BSA-RTIL binding isotherm constructed from conductometric measurements is found to be well reproduced from fluorescence spectroscopy and thus revealing the various interaction zones as a function of the RTIL concentration. The present work delivers particular emphasis to delineate the denaturing action of RTIL on the native protein and in complementarity the effect of RTIL binding on functionality of BSA is explored in terms of esterase-like activity of BSA. The intrinsic time-resolved fluorescence decay and rotational-relaxation dynamics of the protein suggests swelling of the protein rather than aggregation during RTIL-induced denaturation. The result of molecular modeling based on blind docking simulation is found to abet the inferences drawn from experimental results reasonably well. The molecular modeling technique reveals the favorable binding location of the RTIL to be in the hydrophobic domain IIIA (drug site 2) of BSA. The thermodynamic parameters evaluated for the RTIL-BSA binding phenomenon also identifies the pivotal role of hydrophobic force in the interaction. PMID:24721594

Paul, Bijan Kumar; Ganguly, Aniruddha; Guchhait, Nikhil

2014-04-01

122

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

123

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.

124

The role of structural and fluidic aspects of room temperature ionic liquids in influencing the morphology of CdSe nano/microstructures grown in situ.  

PubMed

RTILs as media to synthesize a variety of nanomaterials are gaining momentum owing to their unique physicochemical properties. However, the fundamental questions regarding the role of the inherent structure of the IL in directing the morphology and the growth mechanism of the nanoparticles are still unexplored. Therefore, an attempt was made in this respect wherein CdSe nanoparticles were synthesized in a neat room temperature ionic liquid (RTIL), 1-ethyl-3-methyl imidazolium ethylsulfate ([EMIM][EtSO4]), under ambient conditions. The IL was found to play three roles, as a solvent, as a stabilizing agent and as a shape directing template. The primary nanoparticles were of the sizes in the range of 2-5 nm, as determined by HR-TEM. These primary nanoparticles grow into nanoflake-like units which further self-assemble and transform into a mixture of anisotropic nanostructures (predominantly 2D sheets and flower-like 3D patterns) as revealed by the SEM studies. The co-existence as well as the stability of these nanomorphologies point towards the intrinsic microheterogeneity prevailing in the IL. Furthermore, the vibrational spectroscopic studies comprising of FT-IR and Raman spectroscopy clearly indicate a sort of accord involving the ?-? stacked aromatic geometry and the hydrogen bonding network (between the cation and the anion) of the IL with the CdSe nanoparticles. Therefore, a suitable mechanism has been provided for the resulting anisotropic nanostructures on the basis of the structural and the fluidic aspects of the IL in conjunction with the surface properties of the transient morphologies involved in the process. To further supplement this, control experiments were facilitated by diluting the IL with different amounts of water and the morphology of the CdSe nanostructures was examined at respective mole fractions of water as well as at different time intervals. PMID:24958339

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

2014-07-15

125

Determination of solute partition behavior with room-temperature ionic liquid based micellar gas-liquid chromatography stationary phases using the pseudophase model.  

PubMed

The use of micelles in ionic liquid based gas-chromatography stationary phases was evaluated using equations derived for a "three-phase" model. This model allows the determination of all three partition coefficients involved in the system, and elucidates the micellar contribution to retention and selectivity. Four types of micellar-ionic liquid columns were examined in this study: 1-butyl-3-methylimidazolium chloride with sodium dodecylsulfate or dioctyl sulfosuccinate, and 1-butyl-3-methylimidazolium hexafluorophosphate with polyoxyethylene-100-stearyl ether or polyoxyethylene-23-lauryl ether. The partition coefficients were measured for a wide range of probe molecules capable of a variety of types and magnitudes of interactions. In general, most probe molecules preferentially partitioned to the micellar pseudophase over the bulk ionic liquid component of the stationary phase. Therefore, addition of surfactant to the stationary phase usually resulted in greater solute retention. It is also shown that the selectivity of the stationary phase is significantly altered by the presence of micelles, either by enhancing or lessening the separation. The effects of surfactant on the interaction parameters of the stationary phase are determined using the Abraham solvation parameter model. The addition of sodium dodecylsulfate and dioctyl sulfosuccinate to 1-butyl-3-methylimidazolium chloride stationary phases generally increased the phase's hydrogen bond basicity and increased the level of dispersion interaction. Polyoxyethylene-100-stearyl ether and polyoxyethylene-23-lauryl ether surfactants, however, enhanced the pi-pi/n-pi, polarizability/dipolarity, and hydrogen bond basicity interactions of 1-butyl-3-methylimidazolium hexafluorophosphate to a greater degree than the ionic surfactants with 1-butyl-3-methylimidazolium chloride. However, these nonionic surfactants appeared to hinder the ability of the stationary phase to interact with solutes via dispersion forces. Therefore, it is possible to effectively predict which analytes will be most highly retained by these micellar-ionic liquid stationary phases. PMID:16569411

Lantz, Andrew W; Pino, Verónica; Anderson, Jared L; Armstrong, Daniel W

2006-05-19

126

Ion transfer processes at the room temperature ionic liquid|aqueous solution interface supported by a hydrophobic carbon nanofibers – silica composite film  

Microsoft Academic Search

A thin film of carbon nanofibers embedded into a hydrophobic sol–gel material and deposited onto tin-doped indium oxide substrate electrodes is employed as a support for liquid|liquid redox systems. The system 1-decyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide|aqueous electrolyte is studied with t-butylferrocene as an electrochemically active component in the ionic liquid phase. Redox processes within the ionic liquid are coupled to ion transfer processes

Ewa Rozniecka; Joanna Niedziolka; Juliette Sirieix-Plenet; Laurent Gaillon; Maria A. Murphy; Frank Marken; Marcin Opallo

2006-01-01

127

Supported phospholipid bilayer interaction with components found in typical room-temperature ionic liquids - a QCM-D and AFM Study.  

PubMed

Quartz crystal microbalance with dissipation (QCM-D) monitoring and atomic force microscopy (AFM) were combined to evaluate the defects created by an ionic liquid anion and a cation in a supported phospholipid bilayer composed of zwitterionic lipids on a silica surface. The cation 1-octyl-3-methyl imidazolium (OMIM(+)) was shown to remove lipids from the bilayer, increase the roughness to approximately 2.8 nm (~0.2 for stable supported bilayer) and possibly redeposit lipids with entrapped water. The anion bis(trifluoromethylsulfonyl)imide (Tf(2)N(-)) was found to leave distinct defects within the bilayer that had large pore-like interiors which left the surrounding bilayer intact. However, the ionic liquid 1-butyl-1-methyl pyrrolidinium bis(trifluoromethylsulfonyl)imide (BMP-Tf(2)N) formed a film over the supported bilayer. This work demonstrates, for the first time, the direct effects common components of ionic liquids have on a supported phospholipids bilayer. PMID:19325765

Evans, Kervin O

2008-04-01

128

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

129

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

130

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

131

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

SciTech Connect

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

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

2008-07-01

132

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

PubMed

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

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

2014-02-20

133

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

134

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

135

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

136

Synthesis of Ionic Liquids.  

National Technical Information Service (NTIS)

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 ...

H. Luo S. Dai

2003-01-01

137

Excitation wavelength dependence of excited state intramolecular proton transfer reaction of 4'-N,N-diethylamino-3-hydroxyflavone in room temperature ionic liquids studied by optical Kerr gate fluorescence measurement.  

PubMed

Excited state intramolecular proton transfer reactions (ESIPT) of 4'-N,N-diethylamino-3-hydroxyflavone (DEAHF) in ionic liquids have been studied by steady-state and time-resolved fluorescence measurements at different excitation wavelengths. Steady-state measurements show the relative yield of the tautomeric form to the normal form of DEAHF decreases as excitation wavelength is increased from 380 to 450 nm. The decrease in yield is significant in ionic liquids that have cations with long alkyl chains. The extent of the decrease is correlated with the number of carbon atoms in the alkyl chains. Time-resolved fluorescence measurements using optical Kerr gate spectroscopy show that ESIPT rate has a strong excitation wavelength dependence. There is a large difference between the spectra at a 200 ps delay from different excitation wavelengths in each ionic liquid. The difference is pronounced in ionic liquids having a long alkyl chain. The equilibrium constant in the electronic excited state obtained at a 200 ps delay and the average reaction rate are also correlated with the alkyl chain length. Considering the results of the steady-state fluorescence and time-resolved measurements, the excitation wavelength dependence of ESIPT is explained by state selective excitation due to the difference of the solvation, and the number of alkyl chain carbon atoms is found to be a good indicator of the effect of inhomogeneity for this reaction. PMID:24088033

Suda, Kayo; Terazima, Masahide; Sato, Hirofumi; Kimura, Yoshifumi

2013-10-17

138

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

139

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

140

Electrochromic properties of poly(3-chlorothiophene) film electrodeposited on a nanoporous TiO 2 surface via a room temperature ionic liquid and its application in an electrochromic device  

Microsoft Academic Search

Poly(3-chlorothiophene) (PClT) was electrochemically synthesized on a nanoporous TiO2 surface in the ionic liquid 1-butyl-3-metyllimidazolium hexafluorophosphate by galvanostat method to control charge density of 93 mC cm?2. Spectroelectrochemical analysis presented that the PClT\\/TiO2 nanocomposite film had an electronic bandgap of 1.80 eV with a bordeaux color in the reduced form and a dark blue color in the oxidized form. The switching ability

Yuehong Pang; Xiaoyu Li; Guoyue Shi; Fei Wang; Litong Jin

2008-01-01

141

Facilitated transfer of alkali-metal cations by dibenzo-18-crown-6 across the electrochemically polarized interface between an aqueous solution and a hydrophobic room-temperature ionic liquid.  

PubMed

The facilitated transfer of alkali metal cations (Li+, Na+, K+, Rb+, Cs+) by dibenzo-18-crown-6 (DB18C6) across the electrochemically polarizable interface between an aqueous solution (W) and a hydrophobic ionic liquid, N-octadecylisoquinolinium tetrakis[3,5-bis(trifluoromethyl)phenyl]borate ([C18Iq][TFPB]), has been studied using cyclic voltammetry at the interface formed at the tip of a micropipet. In cyclic voltammograms (CVs), the current due to the facilitated transfer of the cations by DB18C6 from W to [C18Iq][TFPB] can be measured within the polarized potential window of the [C(18)Iq][TFPB]|W interface. The stoichiometry of the complexes in [C18Iq][TFPB] for Li+, Na+, K+, and Rb+ are found to be 1:1 while for the Cs+ transfer both 1:1 and 1:2 complexes are likely to be formed. The formation constants of the 1:1 complexes for Li+, Na+, K+, and Rb+ in [C18Iq][TFPB], , evaluated from CVs are log = 5.0, 7.0, 8.2, and 7.3, respectively. The value for K+ is 1 order of magnitude greater than that for Na+. This higher selectivity of DB18C6 to K+ over Na+ in [C18Iq][TFPB] compared with that in molecular solvents suggests that the RTIL provides a unique solvation environment for the complexations of DB18C6 with the ions. PMID:16906727

Nishi, Naoya; Murakami, Hiroshi; Imakura, Seiichi; Kakiuchi, Takashi

2006-08-15

142

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

SciTech Connect

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

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

1994-03-28

143

Room Temperature Single-Photon Source: Single-Dye Molecule Fluorescence in Liquid Crystal Host  

SciTech Connect

OAK-(B204)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 was avoided over the course of more than 1 h of continuous 532-nm excitation. Liquid crystal hosts (including liquid crystal oligomers/polymers) permit further increase of the efficiency of the source: (1) by aligning the dye molecules along a direction preferable for the maximum excitation efficiency; (2) by tuning a one-dimensional (1-D) photonic-band-gap microcavity of planar-aligned cholesteric (chiral nematic) liquid crystal layer to the dye fluorescence band.

Lukishova, S.G.; Schmid, A.W.; McNamara, A.J.; Boyd, R.W.; Stroud, C.R.Jr.

2003-12-31

144

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

145

Experimental Investigation of Multilayer Insulation With Room Temperature Outside and Liquid Helium Temperature Inside  

Microsoft Academic Search

Experiments on multilayer insulation were conducted with the conditions of room temperature outside and liquid helium temperature (4.2K) inside. By varying the total number of radiation shields, heat trans fer rate and transverse layer-by-layer temperature distribution were measured. Experimental data with liquid nitrogen (77K) were also ob tained and the difference in heat transfer rate between from room tempera ture

N. Inai

1977-01-01

146

Liquid Phase Chemical-Enhanced Oxidation for GaAs Operated Near Room Temperature  

Microsoft Academic Search

A new chemical enhanced oxidation method for gallium arsenide (GaAs) in liquid phase near room temperature (40°C 70°C) is proposed and investigated. Featureless oxide layers with good uniformity and reliability can be grown efficiently on GaAs without any extra energy source. A relatively high oxidation rate (~=1000 Å\\/h), about 50 times higher than that obtained during oxidation in boiling water

Hwei-Heng Wang; Chien-Jung Huang; Yeong-Her Wang; Mau-Phon Houng

1998-01-01

147

Switching and characteristic dielectric parameters of a room temperature antiferroelectric liquid crystal mixture  

Microsoft Academic Search

The switching and dielectric properties of a room temperature bicomponent antiferroelectric liquid crystal mixture have been investigated as a function of temperature and frequency. Thermodynamic, optical texture, and dielectric studies carried out on the mixture show the phase sequence of CrSmIA*SmCA*SmC*SmA*Iso. Spontaneous polarization (Ps), switching time (ts), and torsional bulk viscosity (gammaphi) have been determined by using polarization reversal method.

Anil Kumar; R. Dhar; V. K. Agrawal; R. Dabrowski; M. Tykarska

2008-01-01

148

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.

149

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

Microsoft Academic Search

A quaternized diol, 3-(trimethylammonio)-1,2-propanediol neutralized with either bromine or iodine, was used to produce a polyurethane cationomer with a poly(tetramethylene oxide) soft segment and a 4,4[prime]-diphenylmethane diisocyanate hard segment. If those cationomers were annealed at room temperature for a period of approximately 1 month in a desiccator filled with dry CaSO[sub 4], differential scanning calorimetry (DSC) studies showed an endotherm

R. J. Goddard; B. P. Grady; S. L. Cooper

1994-01-01

150

Dye-doped cholesteric-liquid-crystal room-temperature single-photon source  

SciTech Connect

Fluorescence antibunching from single terrylene molecules embedded in a cholesteric-liquid-crystal host is used to demonstrate operation of a room-temperature single-photon source. One-dimensional (1-D) photonic-band-gap microcavities in planar-aligned cholesteric liquid crystals with band gaps from visible to near-infrared spectral regions are fabricated. Liquid-crystal hosts (including liquid crystal oligomers and polymers) increase the source efficiency, firstly, by aligning the dye molecules along the direction preferable for maximum excitation efficiency (deterministic molecular alignment provides deterministically polarized output photons), secondly, by tuning the 1-D photonic-band-gap microcavity to the dye fluorescence band and thirdly, by protecting the dye molecules from quenchers, such as oxygen.

Lukishova, S.G.; Schmid, A.W.; Supranowitz, C.M.; Lippa, N.; McNamara, A.J.; Boyd, R.W.; Stroud, Jr., C.R.

2004-06-15

151

Harvesting low grade heat to generate electricity with thermosyphon effect of room temperature liquid metal  

NASA Astrophysics Data System (ADS)

Based on thermosyphon effect of room temperature liquid metal, a technical strategy of harvesting low grade heat to generate electricity was proposed. A conceptual system was constructed and an open circuit voltage of 2.62 V with an electrical output power of 110 mW was yielded when the heating power was 45.6 W. This method resolves the difficulty of installing an electric generator in confined space and significantly enlarges the area for converting heat to electricity. Due to its simplicity, avoidance of moving parts, wide working temperature range, and self powering feature, this electric generation system is extremely reliable, completely silent, and flexible.

Li, Peipei; Liu, Jing

2011-08-01

152

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

ERIC Educational Resources Information Center

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

DuPre, Donald B.; Chapoy, L. Lawrence

1979-01-01

153

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

PubMed

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

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

2013-09-23

154

Factors Influencing Electrochemical Actuation of Polyaniline Fibers in Ionic Liquids  

Microsoft Academic Search

Room-temperature ionic liquids have been demonstrated to be advantageous in the development of conducting polymer electrochemical devices. In this paper, we fabricated electrochemical actuators using polyaniline fibers and ionic liquid electrolytes and investigated factors that influence their actuation performance in the ionic liquid [BMIM][BF4], such as the dopant anion, conductive and mechanical properties of the polyaniline fibers, external load, and

Wen Lu; Benjamin R. Mattes

2005-01-01

155

Switching and characteristic dielectric parameters of a room temperature antiferroelectric liquid crystal mixture  

NASA Astrophysics Data System (ADS)

The switching and dielectric properties of a room temperature bicomponent antiferroelectric liquid crystal mixture have been investigated as a function of temperature and frequency. Thermodynamic, optical texture, and dielectric studies carried out on the mixture show the phase sequence of Cr<--(12.0 °C)-->SmIA*<--(29.1 °C)-->SmCA*<--(91.5 °C)-->SmC*<--(92.9 °C)-->SmA*<--(106.7 °C)-->Iso. Spontaneous polarization (Ps), switching time (ts), and torsional bulk viscosity (??) have been determined by using polarization reversal method. Dielectric spectroscopy of the mixture in the frequency range of 0.1 Hz-10 MHz reveals, eight different modes of relaxation in the paraelectric SmA*, ferroelectric SmC*, antiferroelectric SmCA* and SmIA* phases. Origins of these modes have been identified with the help of frequency, temperature, and bias electric field dependence of various dielectric parameters.

Kumar, Anil; Dhar, R.; Agrawal, V. K.; Dabrowski, R.; Tykarska, M.

2008-09-01

156

Ionic liquid mediated magnesium ion conduction in poly(ethylene oxide) based polymer electrolyte  

Microsoft Academic Search

Magnesium ion conduction in poly(ethylene oxide) (PEO) based polymer electrolyte incorporated with room temperature ionic liquid (RTIL) is reported. The electrolyte films comprise the PEO complexed with magnesium trifluoromethanesulfonate (or magnesium triflate) added with different amount of ionic liquid, 1-ethyl-3-methylimidazolium trifluoromethanesulfonate (EMITf). The polymer electrolyte with ?50wt.% of ionic liquid offers a maximum electrical conductivity of ?5.6×10?4Scm?1 at room temperature

Yogesh Kumar; S. A. Hashmi; G. P. Pandey

2011-01-01

157

Use of the ionic liquid 1-butyl-3-methylimidazolium hexafluorophosphate in countercurrent chromatography  

Microsoft Academic Search

Room temperature ionic liquids (RTIL) are molten salts that are liquids at room temperature. Their liquid state makes them possible candidates as solvents in countercurrent chromatography (CCC), which uses solvents as both the mobile and stationary phases. The study focuses on 1-butyl-3-methylimidazolium hexafluorophosphate (BMIM PF 6), an easy to synthesize and purify RTIL whose melting point is ?8°C. It is

A. Berthod; S. Carda-Broch

2004-01-01

158

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

159

Direct Writing of Flexible Electronics through Room Temperature Liquid Metal Ink  

PubMed Central

Background Conventional approaches of making a flexible circuit are generally complex, environment unfriendly, time and energy consuming, and thus expensive. Here, we describe for the first time the method of using high-performance GaIn10-based electrical ink, a significantly neglected room temperature liquid metal, as both electrical conductors and interconnects, for directly writing flexible electronics via a rather easy going and cost effective way. Methods The new generation electric ink was made and its wettability with various materials was modified to be easily written on a group of either soft or rigid substrates such as epoxy resin board, glass, plastic, silica gel, paper, cotton, textiles, cloth and fiber etc. Conceptual experiments were performed to demonstrate and evaluate the capability of directly writing the electrical circuits via the invented metal ink. Mechanisms involved were interpreted through a series of fundamental measurements. Results The electrical resistivity of the fluid like GaIn10-based material was measured as 34.5 µ?·cm at 297 K by four point probe method and increased with addition of the oxygen quantity, which indicates it as an excellent metal ink. The conductive line can be written with features that are approximately 10 µm thick. Several functional devices such as a light emitting diode (LED) array showing designed lighting patterns and electrical fan were made to work by directly writing the liquid metal on the specific flexible substrates. And satisfactory performances were obtained. Conclusions The present method opens the way to directly and quickly writing flexible electronics which can be as simple as signing a name or drawing a picture on the paper. The unique merit of the GaIn10-based liquid metal ink lies in its low melting temperature, well controlled wettability, high electrical conductivity and good biocompability. The new electronics writing strategy and basic principle has generalized purpose and can be extended to more industrial areas, even daily life.

Gao, Yunxia; Li, Haiyan; Liu, Jing

2012-01-01

160

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

161

Development of new class of ion conductive polymers based on ionic liquids  

Microsoft Academic Search

A series of polymerizable ionic liquid was synthesized and polymerized to prepare new type polymer electrolytes. The effects of position of imidazolium cation, spacer structure and length, and anion species on the ionic conductivity have been investigated. Polycation-type ionic liquids having flexible long spacer showed the ionic conductivity of about 10?4Scm?1 at room temperature. Polyanion-type ionic liquids without spacer structure

Hiroyuki Ohno; Masahiro Yoshizawa; Wataru Ogihara

2004-01-01

162

Low-pressure CO 2 sorption in ammonium-based poly(ionic liquid)s  

Microsoft Academic Search

Ammonium-based ionic liquid monomers and their corresponding polymers [poly(ionic liquid)s] are synthesized and characterized for CO2 sorption. The polymers have much higher CO2 sorption capacities than the room-temperature ionic liquids and imidazolium-based poly(ionic liquid)s. For example, P[VBTMA][PF6] with polystyrene backbone has a CO2 sorption capacity of 10.67mol%. The CO2 sorption is selective over N2 and O2. The effects of cation,

Jianbin Tang; Huadong Tang; Weilin Sun; Maciej Radosz; Youqing Shen

2005-01-01

163

Physical and electrochemical properties of low-viscosity phosphonium ionic liquids as potential electrolytes  

Microsoft Academic Search

A new group of room temperature ionic liquids based on triethylalkylphosphonium cations together with a bis(trifluoromethylsulfonyl)imide anion as a novel electrolyte is presented in this report. It was found that phosphonium ionic liquids showed lower viscosities and higher conductivities than those of the corresponding ammonium ionic liquids. Particularly, phosphonium ionic liquids containing a methoxy group, triethyl(methoxymethyl)phosphonium bis(trifluoromethylsulfonyl)imide and triethyl(2-methoxyethyl)phosphonium bis(trifluoromethylsulfonyl)imide,

Katsuhiko Tsunashima; Masashi Sugiya

2007-01-01

164

Preparation for nitrocellulose membrane-poly (vinyl alcohol)-ionic imprinting and its application to determine trace copper by room temperature phosphorimetry  

Microsoft Academic Search

Nitrocellulose membrane-poly (vinyl alcohol)-ionic imprinting (NCM-PVA-I-I) was prepared using Cu2+ as template. The cavity in NCM-PVA-I-I matched Cu2+ very well and the selectivity was high. Cu2+ entered the cavity and then could form ionic association ([Cu2+]·[(Fin?)2]) with the anion of fluorescein (Fin?) outside the cavity by electrostatic effect. [Cu2+]·[(Fin?)2] could emit strong and stable room temperature phosphorescence on NCM-PVA-I-I. Its

Zhi-Ming Li; Jia-Ming Liu; Zhen-Bo Liu; Qin-Ying Liu; Xuan Lin; Fei-Ming Li; Min-Lan Yang; Guo-Hui Zhu; Xiao-Mei Huang

2007-01-01

165

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

166

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

167

Ionic liquids screening for desulfurization of natural gasoline by liquid–liquid extraction  

Microsoft Academic Search

Seventy five ionic liquids (ILs) were tested as a sequestering agent of sulfured compounds in natural gasoline (NG). Desulphurization\\u000a of NG was performed by means of liquid–liquid extraction method at room temperature and atmospheric pressure. Experimental\\u000a ILs containing imidazolium, pyridinium, and ammonium cations along with organic and inorganic anions were synthesized conventionally\\u000a and under microwave and sonochemical conditions. The effect

Natalya V. Likhanova; Diego Guzmán-Lucero; Eugenio A. Flores; Paloma García; Marco A. Domínguez-Aguilar; Jorge Palomeque; Rafael Martínez-Palou

2010-01-01

168

Molecular electrostatic properties of ions in an ionic liquid  

Microsoft Academic Search

We have analysed the electronic wave functions from an ab initio simulation of the ionic liquid (room temperature molten salt) dimethyl imidazolium chloride ([dmim][Cl] or [C1mim][Cl]) using localized Wannier orbitals. This allows us to assign electron density to individual ions. The probability distributions of the ionic dipole moments for an isolated ion and for ions in solution are compared. The

Carlos E. Resende Prado; Mario G. Del Pópolo; T. G. A. Youngs; Jorge Kohanoff; R. M. Lynden-Bell

2006-01-01

169

Application of Et3NHCl-AlCl3 Ionic Liquid as an Initiator in Cationic Copolymerization of 1, 3-Pentadiene with Styrene  

Microsoft Academic Search

The random copolymer poly (1, 3-pentadiene-co-styrene) formed through cationic copolymerization using the triethylamine hydrochloride and hydrous aluminium chloride (Et3NHCl-AlCl3) room temperature ionic liquid as initiating agent in toluene was analyzed using IR spectra in conjunction with gel permeation chromatography (GPC). The room temperature ionic liquid was found to have high initiatic activity for copolymerization.

Yuan Yuan WANG; Hui SUN; Juan LI; Dong JIANG; Li Yi DAI

2006-01-01

170

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

171

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

172

Room-temperature saturated ferroelectric polarization in BiFeO3 ceramics synthesized by rapid liquid phase sintering  

Microsoft Academic Search

Single-phased ferroelectromagnet BiFeO3 ceramics with high resistivity were synthesized by a rapid liquid phase sintering technique. Saturated ferroelectric hysteresis loops were observed at room temperature in the ceramics sintered at 880 °C for 450 s. The spontaneous polarization, remnant polarization, and the coercive field are 8.9 muC\\/cm2, 4.0 muC\\/cm2, and 39 kV\\/cm, respectively, under an applied field of 100 kV\\/cm.

Y. P. Wang; L. Zhou; M. F. Zhang; X. Y. Chen; J.-M. Liu; Z. G. Liu

2004-01-01

173

Ionic liquid ethanol sensor.  

PubMed

Ionic liquids containing lithium methylsulfonyl group were prepared from the precursors poly(propylene glycol)-block-(ethylene glycol)-block-(propylene glycol)-bis(2-aminopropyl ether) with different molecular weight. These liquids revealed excellent electrical conductivity in the temperature range -25 to 85 degrees C. Also, they exhibited a high boiling temperature and hence a low vapor pressure in ambient condition. Additionally, they showed a high fluidity with their viscosities being comparative with that of water. To determine the sensitivity of an ethanol sensor by using these ionic liquids, these liquids were subjected into a sequential electrochemical tests with nickel electrodes which performed a high sensitivity for the ethanol sensor. It was found that only the derivative with low molecular weight could detect ethanol. Furthermore, a linear relationship between the response current and the concentration of ethanol was constructed. The detection limit was found to be 0.13% (v/v) and its response time was 336 s. PMID:15142574

Lee, Yuan Gee; Chou, Tse-Chuan

2004-07-30

174

Spotlight on ionic liquids  

Microsoft Academic Search

Ionic liquids are an emerging class of materials with a diverse and extraordinary set of properties. Understanding the origins of these properties and how they can be controlled by design to serve valuable practical applications presents a wide array of challenges and opportunities to the chemical physics and physical chemistry community. We highlight here some of the significant progress already

Edward W. Castner; James F. Wishart

2010-01-01

175

POSS based ionic liquid as an electrolyte for hybrid electrochromic devices  

Microsoft Academic Search

The main objective of this study was to broaden the assortment of I?\\/I3? redox ionic liquids using polyhedral oligomeric silsesquioxanes (POSS) acting as nanobuilding blocks for the construction of functionalized 1,3-alkylimidazolium iodide solid (melting temperature 150–200°C) and room temperature (RT) ionic liquids.The structural characteristics of the synthesised final ionic liquids and the corresponding intermediates were determined using 1H, 29Si NMR

M. ?olovi?; I. Jerman; M. Gaberš?ek; B. Orel

2011-01-01

176

Low viscous and highly conductive phosphonium ionic liquids based on bis(fluorosulfonyl)amide anion as potential electrolytes  

Microsoft Academic Search

The physical and electrochemical properties of room-temperature ionic liquids based on quaternary phosphonium cations together with a bis(fluorosulfonyl)amide anion are presented in this report. The bis(fluorosulfonyl)amide-based phosphonium ionic liquids were relatively low-melting, low viscous and highly conductive when compared to those of the corresponding bis(trifluoromethylsulfonyl)amide-based ionic liquids. Particularly, the ionic liquids containing a methoxy group in the phosphonium cations indicated

Katsuhiko Tsunashima; Atsuko Kawabata; Masahiko Matsumiya; Shun Kodama; Ryuichi Enomoto; Masashi Sugiya; Yoshihito Kunugi

2011-01-01

177

Homopolymer Dissolution in a Hydrophilic Ionic Liquid  

NASA Astrophysics Data System (ADS)

Dissolution, structure, and dynamics of both neutral and charged polymers dissolved in a hydrophilic room temperature ionic liquid (IL), ethylmethylimidazolium ethyl sulfate [EMIM][EtSO4], have been studied by classical physicochemical methods (static and dynamic light scattering, intrinsic viscosity, refractometry) to determine differences in solution behavior from conventional aqueous and organic solvents. This IL is water miscible. Many neutral polymers and charged polymer salts molecularly dissolve, although solubility doesn't correlate with polymer hydrophilicity. Model neutral soluble polymers are polyvinylpyrrolidone and hydroroxyethyl cellulose while sodium poly(styrene sulfonate) and the iodo salt of methyl-quaternized poly(vinyl pyridine) fill the same role for charged polymers. The latter display none of the polyelectrolyte effects found in low ionic strength water, consistent with strong electrostatic screening in IL. In virial coefficient and coil size, the IL acts for these neutral and charged polymers as a classical good solvent. (Support: UMass MRSEC)

Hoagland, David; Harner, John

2010-03-01

178

Ionic liquid–polymer gel electrolytes from hydrophilic and hydrophobic ionic liquids 1 Presented at the Electrochemical Society Symposium: Processes in Polymers and Polymer?Metal Interfaces, Montreal, 4–9 May 1997. 1  

Microsoft Academic Search

Ionic liquid–polymer gels were prepared by incorporating hydrophilic EMIBF4 and EMI(triflate) (EMI+=1-ethyl-3-methylimidazolium) and hydrophobic BMIPF6 (BMI+=1-(1-butyl)-3-methylimidazolium) room-temperature ionic liquids into a poly(vinylidene fluoride)–hexafluoropropylene copolymer (PVdF(HFP)) matrix. Gel electrolytes prepared with ionic liquid:PVdF(HFP) mass ratios of 2:1 exhibited ionic conductivities of >10?3 S cm?1 at room temperature and >10?2 S cm?1 at 100°C. The BMIPF6-PVdF(HFP) gel was incorporated into electrochemical cells,

Joan Fuller; Amy C Breda; Richard T Carlin

1998-01-01

179

Mesoporous Gold and Palladium Nanoleaves from Liquid-Liquid Interface: Enhanced Catalytic Activity of the Palladium Analogue toward Hydrazine-Assisted Room-Temperature 4-Nitrophenol Reduction.  

PubMed

The importance of an interfacial reaction to obtain mesoporous leafy nanostructures of gold and palladium has been reported. A new synthetic strategy involving 1,4-dihydropyridine ester (DHPE) as a potential reducing agent performs exceptionally well for the desired morphologies of both the noble metals at room temperature. The DHPE in turn transforms into its oxidized aromatic form. The as-synthesized gold leaves exhibit high surface-enhanced Raman scattering activity with rhodamine 6G (R6G) due to their hyperbranched structure. It is worthwhile that as-synthesized porous architectures of palladium support the room-temperature hydrogenation of 4-nitrophenol (4-NP) by hydrazine hydrate (N2H4·H2O), reported for the first time. Furthermore, MPL exhibits exceptionally good catalytic activity toward electrooxidation of formic acid. Therefore, an aromaticity driven synthetic technique achieves a rationale to design leafy nanostructures of noble metals from the liquid-liquid interface for multifaceted applications. PMID:24873275

Dutta, Soumen; Sarkar, Sougata; Ray, Chaiti; Roy, Anindita; Sahoo, Ramkrishna; Pal, Tarasankar

2014-06-25

180

Criteria for solvate ionic liquids.  

PubMed

Certain concentrated mixtures of salts and solvents are not simply "solutions" anymore, but they may be described as "ionic liquids". In this perspective paper, we describe possible criteria for the new family of ionic liquids: "solvate" ionic liquids. This subclass of ionic liquids was originally proposed by Angell et al. in their recent review; however, their criteria remain to be debated. Concentrated mixtures of lithium salts and organic solvents are useful models for these solvate ionic liquids, and the effects of the salt concentration, types of solvents, and counter anions of the lithium salts on their structure and properties have been explored to enable contrast with traditional solutions, and to help determine whether a given mixture belongs to the solvate ionic liquid or not. PMID:24676567

Mandai, Toshihiko; Yoshida, Kazuki; Ueno, Kazuhide; Dokko, Kaoru; Watanabe, Masayoshi

2014-05-21

181

Liquid polystyrene: a room-temperature photocurable soft lithography compatible pour-and-cure-type polystyrene.  

PubMed

Materials matter in microfluidics. Since the introduction of soft lithography as a prototyping technique and polydimethylsiloxane (PDMS) as material of choice the microfluidics community has settled with using this material almost exclusively. However, for many applications PDMS is not an ideal material given its limited solvent resistance and hydrophobicity which makes it especially disadvantageous for certain cell-based assays. For these applications polystyrene (PS) would be a better choice. PS has been used in biology research and analytics for decades and numerous protocols have been developed and optimized for it. However, PS has not found widespread use in microfluidics mainly because, being a thermoplastic material, it is typically structured using industrial polymer replication techniques. This makes PS unsuitable for prototyping. In this paper, we introduce a new structuring method for PS which is compatible with soft lithography prototyping. We develop a liquid PS prepolymer which we term as "Liquid Polystyrene" (liqPS). liqPS is a viscous free-flowing liquid which can be cured by visible light exposure using soft replication templates, e.g., made from PDMS. Using liqPS prototyping microfluidic systems in PS is as easy as prototyping microfluidic systems in PDMS. We demonstrate that cured liqPS is (chemically and physically) identical to commercial PS. Comparative studies on mouse fibroblasts L929 showed that liqPS cannot be distinguished from commercial PS in such experiments. Researchers can develop and optimize microfluidic structures using liqPS and soft lithography. Once the device is to be commercialized it can be manufactured using scalable industrial polymer replication techniques in PS - the material is the same in both cases. Therefore, liqPS effectively closes the gap between "microfluidic prototyping" and "industrial microfluidics" by providing a common material. PMID:24887072

Nargang, Tobias M; Brockmann, Lara; Nikolov, Pavel Mitkov; Schild, Dieter; Helmer, Dorothea; Keller, Nico; Sachsenheimer, Kai; Wilhelm, Elisabeth; Pires, Leonardo; Dirschka, Marian; Kolew, Alexander; Schneider, Marc; Worgull, Matthias; Giselbrecht, Stefan; Neumann, Christiane; Rapp, Bastian E

2014-08-01

182

Room temperature compressibility and diffusivity of liquid water from first principles.  

PubMed

The isothermal compressibility of water is essential to understand its anomalous properties. We compute it by ab initio molecular dynamics simulations of 200 molecules at five densities, using two different van der Waals density functionals. While both functionals predict compressibilities within ~30% of experiment, only one of them accurately reproduces, within the uncertainty of the simulation, the density dependence of the self-diffusion coefficient in the anomalous region. The discrepancies between the two functionals are explained in terms of the low- and high-density structures of the liquid. PMID:24320334

Corsetti, Fabiano; Artacho, Emilio; Soler, José M; Alexandre, S S; Fernández-Serra, M-V

2013-11-21

183

Photodissociation of ICN in polar solvents: Evidence for long lived rotational excitation in room temperature liquids  

NASA Astrophysics Data System (ADS)

Ultrafast polarized pump-probe spectroscopy has been used to study the ICN A~ band photodissociation dynamics in several molecular liquids (water, ethanol, methanol, and chloroform). By exciting at 224 and 255 nm and probing at 385 nm near the gas phase CN B<--X transition, the population and vector correlations in the resulting products have been followed with ~150 fs time resolution. The exhaustive gas-phase reaction dynamics charted for this system indicate that a substantial torque is imparted to the CN fragment in the ground state I dissociation channel while the CN is rotationally cold in the I* channel. The fate of the highly rotationally excited fragment in a liquid environment is explored in the present study. The transient pump-probe anisotropy in ethanol and methanol shows two time scales for decay, ~400 fs and 3-7 ps depending on excitation energy; the two time scales are assigned to the two product channels. The subpicosecond time scale is characteristic of rotational diffusion of thermalized CN while the longer several picosecond time scale suggests the rotationally hot CN rotate nearly freely for several picoseconds in the plane defined by the initial dissociative event. The rotational behavior of a diatomic fragment is considered between the free rotor and small-angle rotational diffusion limits. The CN photoproduct population dynamics are quite varied in the different solvents. In alcohols and chloroform, CN undergoes abstraction reactions with the solvent while in water there is no abstraction. Caging and diffusive geminate recombination dynamics apparently vary markedly in the different solvents; these effects are compared to molecular dynamics results for this photodissociation system. A large isotope effect is observed between H2O and D2O solvents in the product recombination dynamics.

Moskun, Amy C.; Bradforth, Stephen E.

2003-08-01

184

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

185

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

186

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

187

Ionic liquids in confined geometries.  

PubMed

Over recent years the Surface Force Apparatus (SFA) has been used to carry out model experiments revealing structural and dynamic properties of ionic liquids confined to thin films. Understanding characteristics such as confinement induced ion layering and lubrication is of primary importance to many applications of ionic liquids, from energy devices to nanoparticle dispersion. This Perspective surveys and compares SFA results from several laboratories as well as simulations and other model experiments. A coherent picture is beginning to emerge of ionic liquids as nano-structured in pores and thin films, and possessing complex dynamic properties. The article covers structure, dynamics, and colloidal forces in confined ionic liquids; ionic liquids are revealed as a class of liquids with unique and useful confinement properties and pertinent future directions of research are highlighted. PMID:22301770

Perkin, Susan

2012-04-21

188

Stabilizing nanoparticle catalysts in imidazolium-based ionic liquids: A comparative study  

Microsoft Academic Search

Room temperature imidazolium-based ionic liquids such as 1-butyl-3-methylimidazolium hexafluorophosphate (BMIMPF6) have been used as effective liquid media for the synthesis of pure Au and bimetallic PdAu nanoparticles by direct synthesis and phase-transfer methods. The mode-of-stability, long-term stability, and long lifetimes of these ionic-liquid supported nanoparticle catalysts, all of which are important factors in determining the overall “greenness” of such materials,

Priyabrat Dash; Sarah M. Miller; Robert W. J. Scott

2010-01-01

189

Specialist gelator for ionic liquids.  

PubMed

Cyclo(l-beta-3,7-dimethyloctylasparaginyl-L-phenylalanyl) (1) and cyclo(L-beta-2-ethylhexylasparaginyl-L-phenylalanyl) (2), prepared from L-asparaginyl-L-phenylalanine methyl ester, have been found to be specialist gelators for ionic liquids. They can gel a wide variety of ionic liquids, including imizazolium, pyridinium, pyrazolidinium, piperidinium, morpholinium, and ammonium salts. The mean minimum gel concentrations (MGCs) necessary to make gels at 25 degrees C were determined for ionic liquids. The gel strength increased at a rate nearly proportional to the concentration of added gelator. The strength of the transparent gel of 1-butylpyridinium tetrafluoroborate ([C(4)py]BF(4)), prepared at a concentration of 60 g L(-1) (gelator 1/[C(4)py]BF(4)), was ca. 1500 g cm(-2). FT-IR spectroscopy indicated that a driving force for gelation was intermolecular hydrogen bonding between amides and that the phase transition from gel to liquid upon heating was brought about by the collapse of hydrogen bonding. The gels formed from ionic liquids were very thermally stable; no melting occurs up to 140 degrees C when the gels were prepared at a concentration of 70 g L(-1) (gelator/ionic liquid). The ionic conductivities of the gels were nearly the same as those of pure ionic liquids. The gelator had electrochemical stability and a wide electrochemical window. When the gels were prepared from ionic liquids containing propylene carbonate, the ionic conductivities of the resulting gels increased to levels rather higher than those of pure ionic liquids. The gelators also gelled ionic liquids containing supporting electrolytes. PMID:16262296

Hanabusa, Kenji; Fukui, Hiroaki; Suzuki, Masahiro; Shirai, Hirofusa

2005-11-01

190

Ionic liquids in electrochromic devices  

Microsoft Academic Search

The ionic liquid (PYR14TFSI) has proved to be the key material to make a Li-ion conducting element of a complete electrochromic device, when interposed between transparent film electrodes like WO3 and Li-charged V2O5. The key features of this ionic liquid and its mixtures with LiTFSI are the excellent transparency in the visible and NIR optical regions, the good ionic conductivity

A. Brazier; G. B. Appetecchi; S. Passerini; A. Surca Vuk; B. Orel; F. Donsanti; F. Decker

2007-01-01

191

Use of ionic liquids in a lipase-facilitated supported liquid membrane  

Microsoft Academic Search

A lipase-facilitated transport of 4-phenoxybutyric acid, 3-phenoxypropionic acid, 2-phenylpropionic acid, 2-phenoxybutyric acid, mandelic acid and 2-amino-2-phenylbutyric acid was carried out using a supported liquid membrane based on room temperature ionic liquids. There were marked differences in the permeate fluxes of various organic acids due to the substrate specificity of the lipases. The maximum permeate flux (44×10-2 mmol cm-2?×?h) was obtained using

Eijiro Miyako; Tatsuo Maruyama; Noriho Kamiya; Masahiro Goto

2003-01-01

192

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

National Technical Information Service (NTIS)

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 fl...

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

2012-01-01

193

Phase transition and decomposition temperatures, heat capacities and viscosities of pyridinium ionic liquids  

Microsoft Academic Search

Ionic liquids are organic salts with low melting points. Many of these compounds are liquid at room temperature in their pure state. Since they have negligible vapor pressure and would not contribute to air pollution, they are being intensively investigated for a variety of applications, including as solvents for reactions and separations, as non-volatile electrolytes, and as heat transfer fluids.

Jacob M. Crosthwaite; Mark J. Muldoon; JaNeille K. Dixon; Jessica L. Anderson; Joan F. Brennecke

2005-01-01

194

Dynamically coating the capillary with 1-alkyl-3-methylimidazolium-based ionic liquids for separation of basic proteins by capillary electrophoresis  

Microsoft Academic Search

Ionic substances with melting points close to room temperature are referred to as ionic liquids. Because ionic liquids are environmentally benign and are good solvents for a wide range of both organic and inorganic materials, interest for their potential uses in different chemical processes is increasing. In this paper, a capillary electrophoretic method for the analysis of basic proteins including

Ting-Fu Jiang; Yan-Long Gu; Bing Liang; Ju-Bai Li; Yan-Ping Shi; Qing-Yu Ou

2003-01-01

195

Room temperature spontaneous exfoliation of organo-clay in liquid polybutadiene: Effect of polymer end-groups and the alkyl tail number of organic modifier  

Microsoft Academic Search

Disorderly exfoliated telechelic liquid polybutadiene\\/organo-clay nanocomposite gel was, for the first time, successfully prepared at room temperature of 26°C by simply compounding of carboxyl-terminated polybutadiene (CTPB) with organo-clay containing surfactant modifier with two alkyl tails. The dispersion behavior of organo-clay in liquid polybutadiene\\/organo-clay nanocomposite gels were systematically investigated using X-ray diffraction (XRD), transmission electron microscopy (TEM), rheology and compatibility experiments,

Jianjun Zhu; Xiaoliang Wang; Fangfang Tao; Gi Xue; Tiehong Chen; Pingchuan Sun; Qinghua Jin; Datong Ding

2007-01-01

196

Novel applications of ionic liquids in materials processing  

NASA Astrophysics Data System (ADS)

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

Reddy, Ramana G.

2009-05-01

197

Pyrrolidinium Imides: Promising Ionic Liquids for Direct Capture of Elemental Mercury from Flue Gas  

Microsoft Academic Search

A new approach to vapor phase elemental mercury capture has been explored; this approach exploits an ionic liquid coating\\u000a layer to oxidize elemental mercury for subsequent immobilization by chelating ligands. The room temperature ionic liquid 1-butyl-1-methyl\\u000a pyrrolidinium bis(trifluoromethane sulfonyl)imide (P14) was selected for study based on its oxidation potential window, thermal stability, and low vapor pressure. Tests were also\\u000a completed

Lei Ji; Stephen W. Thiel; Neville G. Pinto

2008-01-01

198

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

199

Aggregation behavior of long-chain imidazolium ionic liquids in ethylammonium nitrate  

Microsoft Academic Search

The aggregation behavior of long-chain imidazolium ionic liquids, 1-alkyl-3-methyl-imidazolium bromide (CnmimBr, n?=?12, 14, 16) was studied by surface tension measurements in a room temperature ionic liquid, ethylammonium nitrate (EAN),\\u000a at various temperatures. A series of parameters including critical micelle concentration (cmc), surface tension at the cmc\\u000a (?\\u000a cmc), and the effectiveness of surface tension reduction (?cmc) were obtained. In addition,

Wenpei Kang; Bin Dong; Yanan Gao; Liqiang Zheng

2010-01-01

200

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

201

Nonconvective mixing of miscible ionic liquids.  

PubMed

Ionic liquids (ILs) are ionic compounds that are liquid at room temperature. We studied the spontaneous mixing behavior between two ILs, ethylammonium nitrate (EAN) and 1-butyl-3-methylimidazolium hexafluorophosphate ([BMIM][PF6]), and observed notable phenomena. Experimental studies showed that the interface between the two ILs was unusually long-lived, despite the ILs being miscible with one another. Molecular dynamics (MD) simulations supported these findings and provided insight into the micromixing behavior of the ILs. We found that not only did the ions experience slow diffusion as they mix but also exhibited significant ordering into distinct regions. We suspect that this ordering disrupted concentration gradients in the direction normal to the interface, thus hindering diffusion in this direction and allowing the macroscopic interface to remain for long periods of time. Intermolecular interactions responsible for this behavior included the O-NH interaction between the EAN ions and the carbon chain-carbon chain interactions between the [BMIM](+) cations, which associate more strongly in the mixed state than in the pure IL state. PMID:23855707

Frost, Denzil S; Machas, Michael; Perea, Brian; Dai, Lenore L

2013-08-13

202

Hydrophobic ionic liquids  

DOEpatents

Ionic liquids having improved properties for application in non-aqueous batteries, electrochemical capacitors, electroplating, catalysis and chemical separations are disclosed. Exemplary compounds have one of the following formulas shown in a diagram wherein R{sub 1}, R{sub 2}, R{sub 3}, R{sub 4}, R{sub 5}, and R{sub 6} are either H; F; separate alkyl groups of from 1 to 4 carbon atoms, respectively, or joined together to constitute a unitary alkylene radical of from 2 to 4 carbon atoms forming a ring structure converging on N; or separate phenyl groups; and wherein the alkyl groups, alkylene radicals or phenyl groups may be substituted with electron withdrawing groups, preferably F-, Cl-, CF{sub 3}-, SF{sub 5}-, CF{sub 3}S-, (CF{sub 3}){sub 2}CHS- or (CF{sub 3}){sub 3}CS-; and X{sup {minus}} is a non-Lewis acid-containing polyatomic anion having a van der Waals volume exceeding 100 {angstrom}{sup 3}. 4 figs.

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

1998-10-27

203

Hydrophobic ionic liquids  

DOEpatents

Ionic liquids having improved properties for application in non-aqueous batteries, electrochemical capacitors, electroplating, catalysis and chemical separations are disclosed. Exemplary compounds have one of the following formulas: ##STR1## wherein R.sub.1, R.sub.2, R.sub.3, R.sub.4, R.sub.5, and R.sub.6 are either H; F; separate alkyl groups of from 1 to 4 carbon atoms, respectively, or joined together to constitute a unitary alkylene radical of from 2 to 4 carbon atoms forming a ring structure converging on N; or separate phenyl groups; and wherein the alkyl groups, alkylene radicals or phenyl groups may be substituted with electron withdrawing groups, preferably F--, Cl--, CF.sub.3 --, SF.sub.5 --, CF.sub.3 S--, (CF.sub.3).sub.2 CHS-- or (CF.sub.3).sub.3 CS--; and X.sup.- is a non-Lewis acid-containing polyatomic anion having a van der Waals volume exceeding 100 .ANG..sup.3.

Koch, Victor R. (Lincoln, MA); Nanjundiah, Chenniah (Lynn, MA); Carlin, Richard T. (Nashua, NH)

1998-01-01

204

A Novel Ionic-Liquid Strain Sensor for Large-Strain Applications  

Microsoft Academic Search

A novel liquid strain sensor was developed by using ldquoroom-temperature ionic liquidrdquo as the piezoresistive gauge material. Polydimethylsiloxane, with microchannels, was used to form gauge structures, and carbon fibers were used as electrodes. The strain performance was examined by electrochemical impedance spectroscopy at room temperature, and curve fitting was applied for explaining the strain response. The results show that a

Yun Zhu; Chen Chao; Ching-Hsiang Cheng; Wallace Woon-Fong Leung

2009-01-01

205

Application of ionic liquids as low-volatility plasticizers for PMMA  

Microsoft Academic Search

Room temperature ionic liquids (ILs) based on imidazolium salts, were found to be excellent plasticizers for poly(methyl methacrylate), with improved thermal stability, and the ability to reduce glass transition temperatures to near 0 °C. Because ILs have environmentally benign properties, they can be used in place of traditional chemicals in numerous products and processes. In this work, PMMA was formulated

Mark P Scott; Mustafizur Rahman; Christopher S Brazel

2003-01-01

206

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

Microsoft Academic Search

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 diffusion and the five-ring structure of sulfonium was benefit for fast triiodide ion

Lei Guo; Xu Pan; Meng Wang; Changneng Zhang; Xiaqin Fang; Shuanghong Chen; Songyuan Dai

2011-01-01

207

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

208

Effect of Titanium Substitution on the Compatiblity of Electrodeswith Pyrrolidinium-Based Ionic Liquid Electrolytes  

Microsoft Academic Search

The quest for the development of rechargeable lithium-metal batteries has attracted vigorous worldwide research efforts because this system offers the highest theoretical specific energy [1]. For this to be achieved, the repetitive deposition and stripping of lithium must be close to fully reversible. Thus, alternative electrolytes have been investigated, such as the room-temperature ionic liquid (RTILs). Lithium can be cycled

Juliette A. Saint; Joon-Ho Shin; Adam Best; Anthony Hollenkamp; John Kerr; Marca M. Doeff

2007-01-01

209

Enhancing the sensitivity of ionic liquid sensors for methane detection with polyaniline template  

Microsoft Academic Search

Flammable gas sensors are essential in occupational health and safety to prevent fire or explosion in gas facilities and underground mining. Our early study demonstrated that ionic liquid (IL)\\/quartz crystal microbalance (QCM) gas sensors and sensor arrays were excellent for the detection of various organic vapors at both room temperature and elevated temperatures. In this paper, we developed a general

Xiaoxia Jin; Lei Yu; Xiangqun Zeng

2008-01-01

210

Improved ionic conductivity of nitrile rubber\\/ionic liquid composites  

Microsoft Academic Search

Polymer electrolytes with high ionic conductivity and good elasticity were prepared by mixing nitrile rubber (poly(acrylonitrile-co-butadiene) rubber; NBR) with ionic liquid, N-ethylimidazolium bis(trifluoromethanesulfonyl)imide (EImTFSI). The NBR\\/EImTFSI composites were obtained as homogeneous and transparent films when the ionic liquid content was less than 60wt%. Raman spectroscopy suggested the interaction between nitrile group of NBR and TFSI anion. Sample with ionic liquid

Edy Marwanta; Tomonobu Mizumo; Nobuhumi Nakamura; Hiroyuki Ohno

2005-01-01

211

Thermophysical properties of ionic liquids.  

PubMed

Low melting point salts which are often classified as ionic liquids have received significant attention from research groups and industry for a range of novel applications. Many of these require a thorough knowledge of the thermophysical properties of the pure fluids and their mixtures. Despite this need, the necessary experimental data for many properties is scarce and often inconsistent between the various sources. By using accurate data, predictive physical models can be developed which are highly useful and some would consider essential if ionic liquids are to realize their full potential. This is particularly true if one can use them to design new ionic liquids which maximize key desired attributes. Therefore there is a growing interest in the ability to predict the physical properties and behavior of ionic liquids from simple structural information either by using group contribution methods or directly from computer simulations where recent advances in computational techniques are providing insight into physical processes within these fluids. Given the importance of these properties this review will discuss the recent advances in our understanding, prediction and correlation of selected ionic liquid physical properties. PMID:21107798

Rooney, David; Jacquemin, Johan; Gardas, Ramesh

2010-01-01

212

Particle aggregation mechanisms in ionic liquids.  

PubMed

Aggregation of sub-micron and nano-sized polystyrene latex particles was studied in room temperature ionic liquids (ILs) and in their water mixtures by time-resolved light scattering. The aggregation rates were found to vary with the IL-to-water molar ratio in a systematic way. At the water side, the aggregation rate is initially small, but increases rapidly with increasing IL content, and reaches a plateau value. This behaviour resembles simple salts, and can be rationalized by the competition of double-layer and van der Waals forces as surmised by the classical theory of Derjaguin, Landau, Verwey, and Overbeek (DLVO). At the IL side, aggregation slows down again. Two generic mechanisms could be identified to be responsible for the stabilization in ILs, namely viscous stabilization and solvation stabilization. Viscous stabilization is important in highly viscous ILs, as it originates from the slowdown of the diffusion controlled aggregation due to the hindrance of the diffusion in a viscous liquid. The solvation stabilization mechanism is system specific, but can lead to a dramatic slowdown of the aggregation rate in ILs. This mechanism is related to repulsive solvation forces that are operational in ILs due to the layering of the ILs close to the surfaces. These two stabilization mechanisms are suspected to be generic, as they both occur in different ILs, and for particles differing in surface functionalities and size. PMID:24727976

Szilagyi, Istvan; Szabo, Tamas; Desert, Anthony; Trefalt, Gregor; Oncsik, Tamas; Borkovec, Michal

2014-04-23

213

Electrodeposition of chalcopyrite films from ionic liquid electrolytes  

Microsoft Academic Search

An air and water stable room-temperature ionic liquid based on choline chloride\\/urea eutectic mixture has been investigated as a system for the electrodeposition of CuInSe2 (CIS) and Cu(In,Ga)Se2 (CIGS) films for photovoltaic applications. Deposition potentials and bath compositions were optimized to obtain Cu–In, Cu–In–Se and Cu–In–Ga–Se precursor films, which were selenized in a tube furnace at 500 °C for 30 min to

D. D. Shivagan; P. J. Dale; A. P. Samantilleke; L. M. Peter

2007-01-01

214

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

215

Corresponding States in Solutions of Ionic Liquids  

Microsoft Academic Search

Until recently, liquid-liquid phase transitions in ionic solutions were observed only on very few systems (1). The salts used were chemically rather unstable. Now, a great number of rather stable salts with melting points below 100°C, termed ionic liquids, are available. A substantial number of solutions of ionic liquids with a critical point at ambient temperatures have been discovered recently,

Wolffram Schröer; Annamaria Butka; Vlad Vale; Jan Köser

216

Functionalized ionic liquids based on guanidinium cations with two ether groups as new electrolytes for lithium battery  

Microsoft Academic Search

Two new functionalized ionic liquids (ILs) based on guanidinium cation with two ether groups and TFSA? anion are synthesized and characterized. Their physicochemical and electrochemical properties, including melting point, thermal stability, density, viscosity, conductivity, and electrochemical window are determined. Both the ILs are liquids at room temperature, and the viscosities are about 60mPas at 25°C. Behavior of lithium redox, chemical

Yide Jin; Shaohua Fang; Li Yang; Shin-ichi Hirano; Kazuhiro Tachibana

2011-01-01

217

R&D of Energetic Ionic Liquids.  

National Technical Information Service (NTIS)

This presentation reviews current research and development of energetic ionic liquids, including state-of-the-art fuel, advanced chemical propulsion for spacecraft, history of energetic ionic liquids, and proposes 'greener' chemical propulsion via energet...

T. Hawkins

2011-01-01

218

Purification of gas with liquid ionic compounds  

US Patent & Trademark Office Database

The present invention provides a method for purifying a gas by contacting the gas with a liquid ionic compound. Natural gas may be purified, removing water and carbon dioxide, by contacting the natural gas with a liquid ionic compound.

2003-06-17

219

Ionic liquid functionalized Janus nanosheets.  

PubMed

Ionic liquid functionalized Janus nanosheets are synthesized by selective treatment of the imidazolin terminated side of Janus nanosheets while the other side is preserved. The Janus performance of the nanosheets and thus emulsion stability are reversibly triggered by anion exchange. PMID:24733114

Ji, Xuyang; Zhang, Qian; Liang, Fuxin; Chen, Qinan; Qu, Xiaozhong; Zhang, Chengliang; Wang, Qian; Li, Jiaoli; Song, Ximing; Yang, Zhenzhong

2014-06-01

220

Ambiphilic dual activation role of a task-specific ionic liquid: 2-hydroxyethylammonium formate as a recyclable promoter and medium for the green synthesis of ?-nitrostyrenes.  

PubMed

A cost-effective task-specific ionic liquid, 2-hydroxyethylammonium formate, efficiently promotes the condensation of nitroalkanes with various aldehydes to produce ?-nitrostyrenes in high to excellent yields at room temperature. This reaction does not involve any hazardous organic solvent and toxic catalyst. The ionic liquid is recovered and recycled for subsequent reactions. In addition, a novel mechanism has been proposed invoking ambiphilic dual activation influence of the ionic liquid. PMID:21047089

Alizadeh, Abdolhamid; Khodaei, Mohammad M; Eshghi, Ali

2010-12-01

221

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

222

Calculations of Hydrogen-Bonding Interactions between Ions in Room-Temperature Molten Salts.  

National Technical Information Service (NTIS)

Mixtures of 1-methyl-3-ethylimidazolium chloride (MEI)C) and A1CI3 form chloroaluminate salts that are liquid well below room temperature. These melts are of interest as electrolytes, as nonaqueous solvents for studying ionic complexes, and as catalytic s...

C. J. Dymek J. J. Stewart

1989-01-01

223

Theory of a reversible redox reaction in an ionic liquid that is coupled to an ion transfer across the aqueous electrolyte\\/ionic liquid interface  

Microsoft Academic Search

A theory is provided for a reversible electro-oxidation of a neutral redox probe dissolved in room-temperature ionic liquid,\\u000a which is sandwiched between an electrode surface and an aqueous solution as a thin film. If the peak potentials in cyclic\\u000a voltammetry depend on the bulk concentration of electrolyte in water, the oxidation is most probably coupled to the transfer\\u000a of anions

Milivoj Lovri?; Šebojka Komorsky-Lovri?; Fritz Scholz

2008-01-01

224

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

225

Characterization of PVdF(HFP) gel electrolytes based on 1-(2-Hydroxyethyl)-3-methyl imidazolium ionic liquids.  

PubMed

Poly(vinylidenefluoride)-hexafluoropropylene (PVdF(HFP))-ionic liquid gel electrolytes were prepared using ionic liquids based on 1-(2-hydroxyethyl)-3-methyl imidazolium tetrafluoroborate and 1-(2-hydroxyethyl)-3-methyl imidazolium hexafluorophosphate. A conventional metathesis reaction was used to prepare these ionic liquids, which have high purity and exhibit a liquid state at room temperature. The prepared polymer-ionic liquid gel proved to be a free-standing and rubbery film in which the degree of transparency differed according to the ratio and type of ionic liquid used. TGA and FTIR analyses confirmed that the solvent, N,N-Dimethylacetamide (DMAC), used for mixing PVdF(HFP) polymer with ionic liquid was almost totally removed during the gelling and drying processes. SEM photographs were taken of the surface structure of the PVdF(HFP)-ionic liquid gel in order to evaluate the morphology of the film's surface according to the mixing ratio and the nature of the ionic liquid. The thermal behaviors of PVdF(HFP)-ionic liquid gels were observed to be similar to those of neat ionic liquids through DSC analysis, and the compatibility between the polymer and ionic liquid was investigated by XRD analysis. The ionic conductivities of all the gels were 10(-3)-10(-5) S cm(-1) in a temperature range of 20-70 degrees C. PMID:16853301

Yeon, Sun-Hwa; Kim, Ki-Sub; Choi, Sukjeong; Cha, Jong-Ho; Lee, Huen

2005-09-29

226

Conductance modulation in topological insulator Bi2Se3 thin films with ionic liquid gating  

NASA Astrophysics Data System (ADS)

A Bi2Se3 topological insulator field effect transistor is investigated by using ionic liquid as an electric double layer gating material, leading to a conductance modulation of 365% at room temperature. We discuss the role of charged impurities on the transport properties. The conductance modulation with gate bias is due to a change in the carrier concentration, whereas the temperature dependent conductance change is originated from a change in mobility. Large conductance modulation at room temperature along with the transparent optical properties makes topological insulators as an interesting (opto)electronic material.

Son, Jaesung; Banerjee, Karan; Brahlek, Matthew; Koirala, Nikesh; Lee, Seoung-Ki; Ahn, Jong-Hyun; Oh, Seongshik; Yang, Hyunsoo

2013-11-01

227

Plastination at Room Temperature  

Microsoft Academic Search

According to the standard plastination procedures, the dehydration by freeze substitution in acetone is normally achieved at -25°C and the forced impregnation of specimens at -15 C C to -25°C in a deep freezer. Now, we have been able to modify the dehydration procedure and use room temperature for dehydration. We also developed a new silicone polymer that can be

Zheng Tianzhong; Liu Jingren; Zhu Kerming

1998-01-01

228

Charge transport in confined ionic liquids  

NASA Astrophysics Data System (ADS)

Charge transport and glassy dynamics in neat and polymerized ionic liquids confined in nanoporous silica are investigated in a wide frequency and temperature ranges by a combination of Broadband Dielectric Spectroscopy and Pulsed Field Gradient Nuclear Magnetic Resonance (PFG NMR). By applying the Einstein-Smoluchowski relations to the dielectric spectra, diffusion coefficients are obtained in quantitative agreement with independent PFG NMR. The impact of geometrical confinement as well as the pore wall-ionic liquid interactions on the overall ionic mobility is explored for diverse categories of ionic liquids. The results are discussed within the framework of dynamic glass transition assisted charge transport in ionic liquids.

Sangoro, Joshua; Iacob, Ciprian; Kipnusu, Wycliffe; Kremer, Friedrich

2011-03-01

229

Fluorescence response of coumarin-153 in N-alkyl-N-methylmorpholinium ionic liquids: are these media more structured than the imidazolium ionic liquids?  

PubMed

The fluorescence behavior of coumarin-153 (C153) has been studied in four N-alkyl-N-methylmorpholinium ionic liquids differing in the alkyl chain length attached to the N-methylmorpholinium cation as a function of the excitation wavelength and temperature to understand some of the physicochemical characteristics of these largely unexplored ionic liquids. While the polarity of the ionic liquid with the smallest alkyl chain length is found comparable to that of the commonly used imidazolium ionic liquids, the probe molecule experiences a less polar environment with increasing chain length of the alkyl group attached to the morpholinium cation. The room temperature steady-state fluorescence spectrum of C153 in these solvents is found to be dependent on the excitation wavelength, and this effect is most pronounced in long chain containing ionic liquids. A bathochromic shift of the fluorescence maximum is observed at higher temperature. The excitation wavelength and temperature dependence of the fluorescence of C153 is explained considering a domain structure of these ionic liquids. The time-resolved fluorescence anisotropy measurements indicate the microviscosity around the probe molecule to be significantly different from the bulk viscosity of the long-chain ionic liquids. The solvent reorganization dynamics, as studied by monitoring the time-dependent fluorescence Stokes shift of C153 in these ionic liquids, is found to be slow and similar to that in imidazolium ionic liquids. The time-resolved measurements under isoviscous conditions seem to provide additional support to the organized domain structure of these ionic liquids. PMID:23083398

Khara, Dinesh Chandra; Samanta, Anunay

2012-11-15

230

Recent advances in the applications of ionic liquids in protein stability and activity: a review.  

PubMed

Room temperatures ionic liquids are considered as miraculous solvents for biological system. Due to their inimitable properties and large variety of applications, they have been widely used in enzyme catalysis and protein stability and separation. The related information present in the current review is helpful to the researchers working in the field of biotechnology and biochemistry to design or choose an ionic liquid that can serve as a noble and selective solvent for any particular enzymatic reaction, protein preservation and other protein based applications. We have extensively analyzed the methods used for studying the protein-IL interaction which is useful in providing information about structural and conformational dynamics of protein. This can be helpful to develop and understanding about the effect of ionic liquids on stability and activity of proteins. In addition, the affect of physico-chemical properties of ionic liquids, viz. hydrogen bond capacity and hydrophobicity on protein stability are discussed. PMID:24599667

Patel, Rajan; Kumari, Meena; Khan, Abbul Bashar

2014-04-01

231

Supramolecular ionic liquid gels for quasi-solid-state dye-sensitized solar cells.  

PubMed

A 1-propyl-3-methylimidazolium iodide based supramolecular ionic liquid gel was prepared through the host-guest interactions between a host of ?-cyclodextrin and a room temperature ionic liquid type guest, 1-ethyl-3-methylimidazolium bis((trifluoromethyl)sulfonyl)imide, which contains bis(trifluoromethylsulfonyl)imide as the guest group. The gel-to-sol phase transition temperature of the prepared supramolecular ionic liquid gel could be tuned by the ratio of host to guest. The synthesized supramolecular ionic liquid gel was further applied in quasi-solid-state electrolyte dye-sensitized solar cells, which showed a power conversion efficiency of 4.79% under the simulated air mass 1.5 solar spectrum illumination at 100 mW cm(-2) and excellent long-term stability. PMID:24779535

Zhang, Wei; Yuan, Chao; Guo, Jiangna; Qiu, Lihua; Yan, Feng

2014-06-11

232

Proton polarization at room temperature  

SciTech Connect

We have polarized protons in naphthalene doped with pentacene at higher temperature ({ge}77 K) and lower magnetic field ({approximately}3 kG) than those for ordinary polarized proton targets. Pentacene molecules have been excited with a laser beam. Protons in naphthalene have been polarized dynamically on the intermediate state of pentacene. We obtain about 13{percent} polarization at liquid nitrogen temperature in about 3kG with a N{sub 2}-laser of about 150 mW. It has been found to be also possible to obtain high polarization at room temperature. {copyright} {ital 1995 American Institute of Physics.}

Daigo, M. [Premedical Course, Wakayama Medical College, Wakayama 649-63 (Japan); Hirota, N. [Department of Chemistry, Kyoto University, Kyoto 606 (Japan); Iinuma, M.; Masaike, A.; Shake, I. [Department of Physics, Kyoto University, Kyoto 606 (Japan); Shimizu, H.M. [National Laboratory for High Energy Physics (KEK), Ibaraki-ken 305 (Japan); Takahashi, Y.; Takizawa, R. [Department of Physics, Kyoto University, Kyoto 606 (Japan); Terazima, M. [Department of Chemistry, Kyoto University, Kyoto 606 (Japan); Yabuzaki, T. [Department of Physics, Kyoto University, Kyoto 606 (Japan)

1995-09-01

233

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

234

Copper(II)-catalyzed aerobic oxidation of primary alcohols to aldehydes in ionic liquid [bmpy]PF6.  

PubMed

A room-temperature aerobic oxidation of primary alcohols to aldehydes catalyzed by the three-component system acetamido-TEMPO/Cu(ClO(4))(2)/DMAP in the ionic liquid [bmpy]PF(6) has been developed, and the catalysts can be recycled and reused for five runs without any significant loss of catalytic activity. [reaction: see text] PMID:16092851

Jiang, Nan; Ragauskas, Arthur J

2005-08-18

235

EFFECTS OF IONIC LIQUIDS ON THE SURVIVAL, MOVEMENT, AND FEEDING BEHAVIOR OF THE FRESHWATER SNAIL, PHYSA ACUTA  

Microsoft Academic Search

Room-temperature ionic liquids (ILs) are being promoted as environmentally friendly alternatives to volatile organic solvents currently used by industry. Because ILs are novel and not yet in widespread use, their potential impact on aquatic organisms is unclear. We studied the effects of several ILs on the survivorship and behavior (movement and feeding rates) of the freshwater pulmonate snail, Physa acuta.

Randall J. Bernot; Erin E. Kennedy; Gary A. Lamberti

2005-01-01

236

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

237

Thermal and electrochemical properties of ionic liquids based on N-methyl-N-alkyl morpholinium cations  

Microsoft Academic Search

A series of ionic liquids based on morpholinium cations were prepared. N-alkyl-N-methylmorpholinium bromide, N-alkyl-N-methylmorpholinium\\u000a tetrafluoroborate, N-alkyl-N-methylmorpholinium hexafluorophosphate and N-alkyl-N-methylmorpholinium bis(trifluoromethanesulfonyl)imide\\u000a were synthesized, and then thermal and electrochemical properties of prepared ionic liquids were measured. These morpholinium\\u000a salts were found to be thermally stable near 673 K and electrochemically stable up to 6 V at room temperature. In conclusion,\\u000a these new

Sukjeong Choi; Ki-Sub Kim; Jong-Ho Cha; Huen Lee; Jae Seung Oh; Byoung-Bae Lee

2006-01-01

238

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

239

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

240

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

Microsoft Academic Search

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

Takaya Sato; Gen Masuda; Kentaro Takagi

2004-01-01

241

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 (C4 mim) 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

242

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

243

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

Microsoft Academic Search

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 I3- diffusion and the five-ring structure of sulfonium was benefit for fast triiodide ion

Lei Guo; Xu Pan; Meng Wang; Changneng Zhang; Xiaqin Fang; Shuanghong Chen; Songyuan Dai

2011-01-01

244

Immobilization of Cyphos Ionic Liquids in Alginate Capsules for Cd(II) Sorption  

Microsoft Academic Search

Four phosphonium ionic liquids (Cyphos IL-101, IL-105, IL-109, and IL-111) have been immobilized in composite biopolymer capsules (alginate\\/gelatin). The resins were tested for Cd(II) sorption in HCl solutions. Cyphos IL-111 being solid at room temperature, the phase change contributes to the formation of large vesicles in the resin particle. Sorption isotherms were not affected by the anionic counterpart (chloride, dicyanamide,

E. Guibal; A. Figuerola Piñol; M. Ruiz; T. Vincent; C. Jouannin; A. M. Sastre

2010-01-01

245

Synthesis of a Basic Imidazolide Ionic Liquid and Its Application in Catalyzing Knoevenagel Condensation  

Microsoft Academic Search

A novel basic ionic liquid paired by 1-butyl-3-methylimidazolium cation and imidazolide anion ([bmim]Im) was synthesized and its basicity was investigated. The basicity of [bmim]Im approaches to that of [bmim]OH and is much stronger than that of [bmim]OAc. In aqueous solution at room temperature, 2% of [bmim]Im showed good catalytic properties for Knoevenagel condensations between aromatic aldehyde and active methylene compounds

CHEN Xuewei; LI Xuehui; SONG Hongbing; LÜ Yangxiao; WANG Furong; HU Aixi

2008-01-01

246

Preparation and characterisation of high-density ionic liquids incorporating halobismuthate anions.  

PubMed

A range of ionic liquids containing dialkylimidazolium cations and halobismuthate anions ([BiBrxClyIz](-) and [Bi2BrxClyIz](-)) were synthesised by combining dialkylimidazolium halide ionic liquids with bismuth(iii) halide salts. The majority were room temperature liquids, all with very high densities. The neat ionic liquids and their mixtures with 1-butyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide were characterised using Densitometry, Viscometry, NMR Spectroscopy, Electrospray Ionisation Mass Spectrometry (ESI), Liquid Secondary Ion Mass Spectrometry (LSIMS), Matrix-assisted Laser Desorption/Ionization Mass Spectrometry (MALDI), X-Ray Photoelectron Spectroscopy (XPS) and Thermogravimetric Analysis (TGA), to establish their speciation and suitability for high-temperature applications. PMID:24898158

Cousens, Nico E A; Taylor Kearney, Leah J; Clough, Matthew T; Lovelock, Kevin R J; Palgrave, Robert G; Perkin, Susan

2014-06-24

247

Electronic functions of solid-to-liquid interfaces of organic semiconductor crystals and ionic liquid  

NASA Astrophysics Data System (ADS)

The environment of surface electrons at 'solid-to-liquid' interfaces is somewhat extreme, subjected to intense local electric fields or harsh chemical pressures that high-density ionic charge or polarization of mobile molecules create. In this proceedings, we argue functions of electronic carriers generated at the surface of organic semiconductor crystals in response to the local electric fields in the very vicinity of the interface to ionic liquid. The ionic liquids (ILs), or room temperature molten salts, are gaining considerable interest in the recent decade at the prospect of nonvolatile 'green solvents', with the development of chemically stable and nontoxic compounds. Moreover, such materials are also applied to electrolytes for lithium ion batteries and electric double-layer (EDL) capacitors. Our present solid-to-liquid interfaces of rubrene single crystals and ionic liquids work as fast-switching organic field-effect transistors (OFETs) with the highest transconductance, i.e. the most efficient response of the output current to the input voltage, among the OFETs ever built.

Takeya, J.

2008-10-01

248

Mixtures of ionic liquid and organic carbonate as electrolyte with improved safety and performance for rechargeable lithium batteries  

Microsoft Academic Search

In this paper we report the results of physical–chemical and electrochemical investigations performed on ternary mixtures of the room temperature ionic liquid (IL) N-butyl-N-methylpyrrolidinium bis(trifluoromethanesulfonyl)imide (PYR14TFSI), propylene carbonate (PC), and lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) as electrolyte for lithium-ion batteries. The thermal stability, ionic conductivity, viscosity and electrochemical stability windows of all considered mixtures were investigated and compared with those of electrolytes

R.-S. Kühnel; N. Böckenfeld; S. Passerini; M. Winter; A. Balducci

2011-01-01

249

Electrochemical intercalation of lithium into a natural graphite anode in quaternary ammonium-based ionic liquid electrolytes  

Microsoft Academic Search

Electrochemical intercalation of lithium into a natural graphite anode was investigated in electrolytes based on a room temperature ionic liquid consisting of trimethyl-n-hexylammonium (TMHA) cation and bis(trifluoromethanesulfone) imide (TFSI) anion. Graphite electrode was less prone to forming effective passivation film in 1M LiTFSI\\/TMHA-TFSI ionic electrolyte. Reversible intercalation\\/de-intercalation of TMHA cations into\\/from the graphene interlayer was confirmed by using cyclic voltammetry,

Honghe Zheng; Kai Jiang; Takeshi Abe; Zempachi Ogumi

2006-01-01

250

Electrochemical stability of bis(trifluoromethanesulfonyl)imide-based ionic liquids at elevated temperature as a solvent for a titanium oxide bronze electrode  

Microsoft Academic Search

Four different electrolytes are prepared by dissolving a Li salt in three different room-temperature ionic liquids (RTILs) and also in a conventional organic solvent. The cathodic (electrochemical reduction) stability of these electrolytes is compared at both ambient and elevated temperature by potential cycling on a TiO2-B electrode. At room temperature, the stability of pyrrolidinium- and piperidinium-based RTILs is comparable with

Junyoung Mun; Yoon Seok Jung; Taeeun Yim; Hyun Yeong Lee; Hyo-Jin Kim; Young Gyu Kim; Seung M. Oh

2009-01-01

251

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

252

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

PubMed

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(60 +). The setup, the charge breeding technique, breeding efficiencies as well as acceptance and emittance studies are presented. PMID:22380207

Thorn, A; Ritter, E; Ullmann, F; Pilz, W; Bischoff, L; Zschornack, G

2012-02-01

253

Ionic liquids screening for desulfurization of natural gasoline by liquid-liquid extraction.  

PubMed

Seventy five ionic liquids (ILs) were tested as a sequestering agent of sulfured compounds in natural gasoline (NG). Desulphurization of NG was performed by means of liquid-liquid extraction method at room temperature and atmospheric pressure. Experimental ILs containing imidazolium, pyridinium, and ammonium cations along with organic and inorganic anions were synthesized conventionally and under microwave and sonochemical conditions. The effect of the molecular structure of ILs on the desulfurization efficiency of NG with high sulfur content was evaluated. Analysis indicated that the anion type played a more important role than the cation on the desulphurization process. ILs based on halogen-ferrates and halogen-aluminates exhibited the highest efficiency in sulfur removal, and their efficiency is further improved when there is an excess of metallic salt in a ratio of at least 1:1.3 during the synthesis of the corresponding IL. An explanation for the ability of metallic ILs to remove sulfur-containing compounds from natural gasoline based on the ratio of the ionic charge to the atomic radius is proposed. Furthermore, a method to recover and reuse water-sensitive to halogenated precursors is described. PMID:20091120

Likhanova, Natalya V; Guzmán-Lucero, Diego; Flores, Eugenio A; García, Paloma; Domínguez-Aguilar, Marco A; Palomeque, Jorge; Martínez-Palou, Rafael

2010-11-01

254

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

255

Ionic Liquid Crystals as Universal Matrices (Solvents)  

Microsoft Academic Search

\\u000a This paper is devoted to research on ionic liquid crystals in low-melting metal alkanoate systems, which may prove to be universal\\u000a solvents. The main criteria for ionic liquid crystal formation and stability have been established.

T. A. Mirnaya; S. V. Volkov

256

Modification of cationic nanoclays with ionic liquids  

Microsoft Academic Search

As part of a broader effort to develop nanoclays functionalized with different heterocyclic aromatic structures for novel applications, preliminary data are reported on the modification of sodium montmorillonite, a cationic clay, with three low molecular weight pyridinium- and imidazolium-based ionic liquids. Commercially available unmodified clay was treated under different conditions with aqueous solutions of three ionic liquids: N-ethyl pyridinium tetrafluoroborate,

Neung Hyun Kim; Sanjay V. Malhotra; Marino Xanthos

2006-01-01

257

Tuning ionic liquids for hydrate inhibition.  

PubMed

Pyrrolidinium cation-based ionic liquids were synthesized, and their inhibition effects on methane hydrate formation were investigated. It was found that the ionic liquids shifted the hydrate equilibrium line to a lower temperature at a specific pressure, while simultaneously delaying gas hydrate formation. PMID:21547283

Kim, Ki-Sub; Kang, Jeong Won; Kang, Seong-Pil

2011-06-14

258

The Solubility Parameters of Ionic Liquids  

PubMed Central

The Hildebrand’s solubility parameters have been calculated for 18 ionic liquids from the inverse gas chromatography measurements of the activity coefficients at infinite dilution. Retention data were used for the calculation. The solubility parameters are helpful for the prediction of the solubility in the binary solvent mixtures. From the solubility parameters, the standard enthalpies of vaporization of ionic liquids were estimated.

Marciniak, Andrzej

2010-01-01

259

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

260

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

261

Ionic liquid stationary phases for gas chromatography.  

PubMed

This article provides a summary of the development of ionic liquids as stationary phases for gas chromatography beginning with early work on packed columns that established details of the retention mechanism and established working methods to characterize selectivity differences compared with molecular stationary phases through the modern development of multi-centered cation and cross-linked ionic liquids for high-temperature applications in capillary gas chromatography. Since there are many reviews on ionic liquids dealing with all aspects of their chemical and physical properties, the emphasis in this article is placed on the role of gas chromatography played in the design of ionic liquids of low melting point, high thermal stability, high viscosity, and variable selectivity for separations. Ionic liquids provide unprecedented opportunities for extending the selectivity range and temperature-operating range of columns for gas chromatography, an area of separation science that has otherwise been almost stagnant for over a decade. PMID:21290604

Poole, Colin F; Poole, Salwa K

2011-04-01

262

Thermal properties of ionic systems near the liquid-liquid critical point.  

PubMed

Isobaric heat capacity per unit volume, C(p), and excess molar enthalpy, h(E), were determined in the vicinity of the critical point for a set of binary systems formed by an ionic liquid and a molecular solvent. Moreover, and, since critical composition had to be accurately determined, liquid-liquid equilibrium curves were also obtained using a calorimetric method. The systems were selected with a view on representing, near room temperature, examples from clearly solvophobic to clearly coulombic behavior, which traditionally was related with the electric permittivity of the solvent. The chosen molecular compounds are: ethanol, 1-butanol, 1-hexanol, 1,3-dichloropropane, and diethylcarbonate, whereas ionic liquids are formed by imidazolium-based cations and tetrafluoroborate or bis-(trifluromethylsulfonyl)amide anions. The results reveal that solvophobic critical behavior-systems with molecular solvents of high dielectric permittivity-is very similar to that found for molecular binary systems. However, coulombic systems-those with low permittivity molecular solvents-show strong deviations from the results usually found for these magnitudes near the liquid-liquid phase transition. They present an extremely small critical anomaly in C(p)-several orders of magnitude lower than those typically obtained for binary mixtures-and extremely low h(E)-for one system even negative, fact not observed, up to date, for any liquid-liquid transition in the nearness of an upper critical solution temperature. PMID:22149802

Méndez-Castro, Pablo; Troncoso, Jacobo; Pérez-Sánchez, Germán; Peleteiro, José; Romaní, Luis

2011-12-01

263

Thermal properties of ionic systems near the liquid-liquid critical point  

NASA Astrophysics Data System (ADS)

Isobaric heat capacity per unit volume, Cp, and excess molar enthalpy, hE, were determined in the vicinity of the critical point for a set of binary systems formed by an ionic liquid and a molecular solvent. Moreover, and, since critical composition had to be accurately determined, liquid-liquid equilibrium curves were also obtained using a calorimetric method. The systems were selected with a view on representing, near room temperature, examples from clearly solvophobic to clearly coulombic behavior, which traditionally was related with the electric permittivity of the solvent. The chosen molecular compounds are: ethanol, 1-butanol, 1-hexanol, 1,3-dichloropropane, and diethylcarbonate, whereas ionic liquids are formed by imidazolium-based cations and tetrafluoroborate or bis-(trifluromethylsulfonyl)amide anions. The results reveal that solvophobic critical behavior--systems with molecular solvents of high dielectric permittivity--is very similar to that found for molecular binary systems. However, coulombic systems--those with low permittivity molecular solvents--show strong deviations from the results usually found for these magnitudes near the liquid-liquid phase transition. They present an extremely small critical anomaly in Cp--several orders of magnitude lower than those typically obtained for binary mixtures--and extremely low hE--for one system even negative, fact not observed, up to date, for any liquid-liquid transition in the nearness of an upper critical solution temperature.

Méndez-Castro, Pablo; Troncoso, Jacobo; Pérez-Sánchez, Germán; Peleteiro, José; Romaní, Luis

2011-12-01

264

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

2011-09-01

265

system at room temperature  

NASA Astrophysics Data System (ADS)

In this paper, the moderately and lightly doped porous silicon nanowires (PSiNWs) were fabricated by the `one-pot procedure' metal-assisted chemical etching (MACE) method in the HF/H2O2/AgNO3 system at room temperature. The effects of H2O2 concentration on the nanostructure of silicon nanowires (SiNWs) were investigated. The experimental results indicate that porous structure can be introduced by the addition of H2O2 and the pore structure could be controlled by adjusting the concentration of H2O2. The H2O2 species replaces Ag+ as the oxidant and the Ag nanoparticles work as catalyst during the etching. And the concentration of H2O2 influences the nucleation and motility of Ag particles, which leads to formation of different porous structure within the nanowires. A mechanism based on the lateral etching which is catalyzed by Ag particles under the motivation by H2O2 reduction is proposed to explain the PSiNWs formation.

Li, Shaoyuan; Ma, Wenhui; Zhou, Yang; Chen, Xiuhua; Xiao, Yongyin; Ma, Mingyu; Zhu, Wenjie; Wei, Feng

2014-04-01

266

Ionic Liquids as Catalysts for Ethylbenzene Production  

Microsoft Academic Search

\\u000a Chloroaluminate ionic liquids have been assessed as liquid acid catalysts for the alkylation of benzene with ethylene to produce\\u000a ethylbenzene. Detailed comparisons with commercial aluminium(III) chloride catalyst have been carried out, using performance\\u000a indicators such as activity, selectivity and lifetime. Results of the study indicate inferior activity but superior recyclability\\u000a with current generations of ionic liquid catalysts. Calculations suggest that

M. P. Atkins; C. Bowlas; B. Ellis; F. Hubert; A. Rubatto; P. Wasserscheid

267

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

268

Conductance modulation in topological insulator Bi{sub 2}Se{sub 3} thin films with ionic liquid gating  

SciTech Connect

A Bi{sub 2}Se{sub 3} topological insulator field effect transistor is investigated by using ionic liquid as an electric double layer gating material, leading to a conductance modulation of 365% at room temperature. We discuss the role of charged impurities on the transport properties. The conductance modulation with gate bias is due to a change in the carrier concentration, whereas the temperature dependent conductance change is originated from a change in mobility. Large conductance modulation at room temperature along with the transparent optical properties makes topological insulators as an interesting (opto)electronic material.

Son, Jaesung; Banerjee, Karan; Yang, Hyunsoo, E-mail: eleyang@nus.edu.sg [Department of Electrical and Computer Engineering, National University of Singapore, 4 Engineering Drive 3, Singapore 117576 (Singapore)] [Department of Electrical and Computer Engineering, National University of Singapore, 4 Engineering Drive 3, Singapore 117576 (Singapore); Brahlek, Matthew; Koirala, Nikesh; Oh, Seongshik [Department of Physics and Astronomy, Rutgers, The State University of New Jersey, 136 Frelinghuysen Road, Piscataway, New Jersey 08854 (United States)] [Department of Physics and Astronomy, Rutgers, The State University of New Jersey, 136 Frelinghuysen Road, Piscataway, New Jersey 08854 (United States); Lee, Seoung-Ki [School of Advanced Materials Science and Engineering, Sungkyunkwan University, Suwon 440-746 (Korea, Republic of) [School of Advanced Materials Science and Engineering, Sungkyunkwan University, Suwon 440-746 (Korea, Republic of); School of Electrical and Electronic Engineering, Yonsei University, Seoul 120-749 (Korea, Republic of); Ahn, Jong-Hyun [School of Electrical and Electronic Engineering, Yonsei University, Seoul 120-749 (Korea, Republic of)] [School of Electrical and Electronic Engineering, Yonsei University, Seoul 120-749 (Korea, Republic of)

2013-11-18

269

Ionic liquids for energy, materials, and medicine.  

PubMed

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

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

2014-07-22

270

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

NASA Astrophysics Data System (ADS)

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

Lazarus, Laura L.

271

Design and synthesis of photoactive ionic liquids.  

PubMed

Two ionic liquids with photoisomerizable p-hydroxycinnamic acid moieties were synthesized and characterized by X-ray crystallography and DSC, and their photochemistry was studied in solution and neat conditions. Irradiation at absorption maxima led to trans-cis photoisomerization and resulted in significant reduction of melting temperatures of the ionic liquids. X-ray structures of both compounds show an intricate network of supramolecular interactions before irradiation. Physical and chemical transformations are completely reversible upon irradiation at lower wavelengths of ionic liquid solutions in acetonitrile. PMID:24787141

Avó, João; Cunha-Silva, Luís; Lima, João Carlos; Jorge Parola, A

2014-05-16

272

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

273

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

NASA Astrophysics Data System (ADS)

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

Tripathi, Neha; Saha, Satyen

2014-06-01

274

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.

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

2014-01-01

275

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

276

Ionic Liquids as Hypergolic Fuels (Postprint).  

National Technical Information Service (NTIS)

After seminal work presented a decade ago, ionic liquids (IL) have now received a lot of attention as energetic materials for propellant applications. In bipropellant rocket engines, it is desirable to achieve ignition by means of a hypergolic reaction an...

G. Vaghjiani M. Rosander S. Chambreau S. Schneider T. Hawkins

2008-01-01

277

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

278

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

NASA Astrophysics Data System (ADS)

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

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

2014-05-01

279

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

280

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

281

Synthesis of benzylidenated hexopyranosides in ionic liquids.  

PubMed

The synthesis of 4,6-O-benzylidenated monosaccharides and disaccharides has been studied using ionic liquids as a unique solvent alternative. An examination of several imidazolium ionic liquids indicates that the benzylidenation of hexopyranosides in 3-butyl-1-methylimidazolium tetrafluoroborate, [bmim]BF4, gives the highest yields for most of the substrates, and that this solvent system could be readily recycled. PMID:16289411

Zhang, Jianguo; Ragauskas, Arthur J

2005-12-30

282

Study of thioglycosylation in ionic liquids.  

PubMed

A novel, green chemistry, glycosylation strategy was developed based upon the use of ionic liquids. Research studies demonstrated that thiomethyl glycosides could readily be activated with methyl trifluoromethane sulfonate, using 1-butyl-3-methylimidazolium tetrafluoroborate as a solvent. This green chemistry glycosylation strategy provided disaccharides with typical yields averaging 75%. The ionic liquid solvent could be readily reused for five sequential glycosylation reactions with no impact on product yield. PMID:16803635

Zhang, Jianguo; Ragauskas, Arthur

2006-01-01

283

Study of thioglycosylation in ionic liquids  

PubMed Central

A novel, green chemistry, glycosylation strategy was developed based upon the use of ionic liquids. Research studies demonstrated that thiomethyl glycosides could readily be activated with methyl trifluoromethane sulfonate, using 1-butyl-3-methylimidazolium tetrafluoroborate as a solvent. This green chemistry glycosylation strategy provided disaccharides with typical yields averaging 75%. The ionic liquid solvent could be readily reused for five sequential glycosylation reactions with no impact on product yield.

Zhang, Jianguo; Ragauskas, Arthur

2006-01-01

284

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

285

Synthesis of Novel Chiral Ionic Liquid and Its Application in Reduction of Prochiral Ketones to the Corresponding Chiral Alcohols Using NaBH4  

Microsoft Academic Search

A novel chiral ionic liquid (CIL) based on nicotinium salt has been synthesized and used as an efficient asymmetric chiral catalyst for reduction of acetophenone derivatives with NaBH4 in methanol at room temperature. The optically active alcohols were obtained in low to moderate enantiomeric excess in a short reaction time.

Abdol Reza Hajipour; Fatemeh Karimi

2010-01-01

286

Dissolution of wood in ionic liquids.  

PubMed

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-methylimidazolium chloride and 1-allyl-3-methylimidazolium chloride have good solvating power for Norway spruce sawdust and Norway spruce and Southern pine thermomechanical pulp (TMP) fibers. Despite the fact that the obtained solutions were not fully clear, these ionic liquids provided solutions which permitted the complete acetylation of the wood. Alternatively, transparent amber solutions of wood could be obtained when the dissolution of the same lignocellulosic samples was attempted in 1-benzyl-3-methylimidazolium chloride. This realization was based on a designed augmented interaction of the aromatic character of the cation of the ionic liquid with the lignin in the wood. After dissolution, wood can be regenerated as an amorphous mixture of its original components. The cellulose of the regenerated wood can be efficiently digested to glucose by a cellulase enzymatic hydrolysis treatment. Furthermore, completely acetylated wood was found to be readily soluble in chloroform, allowing, for the first time, detailed proton nuclear magnetic resonance (NMR) spectra and NMR diffusion measurements to be made. It was thus demonstrated that the dissolution of wood in ionic liquids now offers a variety of new possibilities for its structural and macromolecular characterization, without the prior isolation of its individual components. Furthermore, considering the relatively wide solubility and compatibility of ionic liquids with many organic or inorganic functional chemicals or polymers, it is envisaged that this research could create a variety of new strategies for converting abundant woody biomass to valuable biofuels, chemicals, and novel functional composite biomaterials. PMID:17907779

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

2007-10-31

287

Ionic liquids: new perspectives for inorganic synthesis?  

PubMed

Ionic liquids are credited with a number of unusual properties. These include a low vapor pressure, a wide liquid-phase range, weakly coordinating properties, and a high thermal/chemical stability. These properties are certainly of great interest for inorganic synthesis and the creation of novel inorganic compounds. On the other hand, the synthesis repertoire for preparing inorganic compounds has always been broad, ranging from syntheses in solutions and melts to solid-state reactions, and from crystal growth in the gas phase to high-pressure syntheses. What new aspects can ionic liquids then add to the synthesis of inorganic compounds? This Minireview uses some early examples to show that the use of ionic liquids indeed provides access to unusual inorganic compounds. PMID:21990270

Freudenmann, Dominic; Wolf, Silke; Wolff, Michael; Feldmann, Claus

2011-11-18

288

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

2014-07-01

289

Full-ionic liquid gel electrolytes: Enhanced photovoltaic performances in dye-sensitized solar cells  

NASA Astrophysics Data System (ADS)

Liquid electrolytes containing redox species have been widely used in dye-sensitized solar cells (DSSCs), whereas the volatility of organic solvents has been a tremendous obstacle for their commercial application. To assemble durable DSSCs, here we report the synthesis of full-ionic liquid electrolyte, in which 1-butyl-3-methylimidazolium nitrate is employed as solvent and 1-methyl-3-propylimidazolium iodide is iodide source. Using the imbibition performance of amphiphilic poly(acrylic acid/gelatin) [poly(AA/GR)] and poly(acrylic acid/cetyltrimethyl ammonium bromide) [poly(AA/CTAB)] matrices, full-ionic liquid electrolytes are imbibed into three-dimensional framework of poly(AA/GR) or poly(AA/CTAB) to form stable gel electrolytes. Room-temperature ionic conductivities as high as 17.82 and 18.44 mS cm-1 are recorded from full-ionic liquid imbibed poly(AA/GR) and poly(AA/CTAB) gel electrolytes, respectively. Promising power conversion efficiencies of 7.19% and 7.15% are determined from their DSSC devices in comparison with 6.55% and 6.12% from traditional acetonitrile-based poly(AA/GR) and poly(AA/CTAB) gel electrolytes, respectively. The new concept along with easy fabrication demonstrates the full-ionic liquid electrolytes to be good alternatives for robust gel electrolytes in quasi-solid-state DSSCs.

Li, Qinghua; Tang, Qunwei; He, Benlin; Yang, Peizhi

2014-10-01

290

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

291

Preparation of Superconducting (TMTSF)2NbF6 by Electrooxidation of TMTSF Using Ionic Liquid as Electrolyte  

Microsoft Academic Search

High-quality single crystals of an organic superconductor (TMTSF)2NbF6 (TMTSF: tetramethyltetraselenafulvalene) were prepared using room-temperature ionic liquid 1-ethyl-3-methylimidazolium·NbF6 as electrolyte. The crystal is isostructural to the other members of the TMTSF superconducting family, (TMTSF)2X with octahedral anions X. The crystal and band structures and temperature dependence of electrical resistivity were reported. The salt exhibited a metal–insulator transition at 12 K due to

Masafumi Sakata; Yukihiro Yoshida; Mitsuhiko Maesato; Gunzi Saito; Kazuhiko Matsumoto; Rika Hagiwara

2006-01-01

292

A Solid State Actuator Based on the PEDOT\\/NBR System: Effect of Anion Size of Imidazolium Ionic Liquid  

Microsoft Academic Search

The fabrication of a dry type conducting polymer actuator is presented using nitrile rubber (NBR) as the base material for the solid polymer electrolyte. A conducting polymer, poly(3,4-ethylenedioxythiophene) (PEDOT), was synthesized on the surface of the NBR by the chemical oxidation polymerization technique, and room temperature ionic liquids (RTIL) based on imidazolium salts, viz. 1-butyl-3-methyl imidazolium X [where X = BF4 ,

M. S. Cho; H. J. Seo; J. D. Nam; Y. Lee; Y. K. Son

2007-01-01

293

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

294

Surface Nanocrystallization of an Ionic Liquid  

NASA Astrophysics Data System (ADS)

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

Jeon, Yoonnam; Vaknin, David; Bu, Wei; Sung, Jaeho; Ouchi, Yukio; Sung, Woongmo; Kim, Doseok

2012-02-01

295

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

296

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

PubMed

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

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

2011-12-28

297

Evidence for enhancing charge collection efficiency with an alternative cost-effective binary ionic liquids electrolyte based dye-sensitized solar cells  

Microsoft Academic Search

To mitigate the mass transfer limitations of a highly viscous room temperature ionic liquid (RTIL) electrolyte, systematic characterizations of viscosity, ionic conductivity, apparent triiodide diffusion coefficient and photovoltaic response of an alternative cost-effective and highly conductive binary RTIL mixture of 1-ethyl-3-methylimidazolium trifluoroacetate (EMIATF) and 1-methyl-3-propylimidazolium iodide (PMII) were investigated. An emphasis was placed on the dynamics of electron transport and

Feng Hao; Hong Lin; Yizhu Liu; Guijun Yang; Gang Wang; Jianbao Li

2011-01-01

298

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

299

Room Temperature Ionic Liquids as Replacements for Traditional Organic Solvents and their Applications Towards “Green Chemistry” in Separation Processes  

Microsoft Academic Search

\\u000a The full effect of Green Chemistry will be realized when the words “environmentally friendly” and “chemistry” can be used\\u000a in the same sentence without seeming to be a contradiction. In an effort to comply with governmental regulations and to spruce\\u000a up the image of the chemical industry, one of the major goals of “green” chemistry is to prevent pollution and

Ann E. Visser; Richard P. Swatloski; W. Matthew Reichert; Heather D. Willauer; Jonathan G. Huddleston; Robin D. Rogers

300

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...

301

Room-Temperature Sulfur Chloride Ionic Liquids in Processes for the Isolation of Noble and other Metals  

Microsoft Academic Search

\\u000a A correlation of interatomic distances (d\\/Å), chalcogen-chlorine bond stretching frequencies (v\\/cm?1) and 35Cl NQR frequencies (MHz) has been performed for crystals of chalcogen chloride complexes of gold(III) and osmium(IV). A conclusion\\u000a has been drawn as to the functional peculiarities of chalcogen chloride molecules being part of complexes. The state of the\\u000a complexes under investigation in nonaqueous polar solvents has been

V. I. Pekhnyo; S. V. Volkov; N. G. Alexandrova

302

Fluorescence Correlation Spectroscopy Evidence for Structural Heterogeneity in Ionic Liquids  

SciTech Connect

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

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

2011-01-01

303

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

304

Unusual redox stability of neptunium in the ionic liquid [Hbet][Tf2N].  

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

2014-06-24

305

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

306

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

307

Polymer electrolyte with ionic liquid for DSSC application  

Microsoft Academic Search

We have investigated the structural and ionic conductivity properties of the polymer electrolyte PEO:KI\\/I2 doped with an ionic liquid 1-ethyl 3-methylimidazolium thio-cyanate (EMImSCN). Incorporation of the ionic liquid (IL) reduced the crystallinity, and enhanced the ionic conductivity. Optimized conductivity was found at 80 wt% of ionic liquid composition. This high electrical conductivity was suitable for dye sensitized solar cell (DSSC)

Pramod K. Singh; Ki-Il Kim; Jae-Wook Lee; Hee-Woo Rhee

2006-01-01

308

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 [C4mim][NTf2] with those for 1-butyl-3-methylimidazolium tetrafluoroborate ([C4mim][BF4]) and 1-butyl-3-methylimidazolium hexafluorophosphate ([C4mim][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

309

Studies on thermal properties of selected aprotic and protic ionic liquids  

SciTech Connect

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

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

2008-01-01

310

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

311

Soft Ionization of Thermally Evaporated Hypergolic Ionic Liquid Aerosols.  

National Technical Information Service (NTIS)

Isolated ion pairs of a conventional ionic liquid, 1-Ethyl-3-Methyl- Imidazolium Bis(trifluoromethylsulfonyl)imide (Emim+) (Tf2N-), and a reactive hypergolic ionic liquid, 1-Butyl-3-Methyl-Imidazolium Dicyanamide (Bmim+) (Dca-), are generated by vaporizin...

A. Golan C. Harmon C. Liu C. J. Koh D. Strasser

2011-01-01

312

Gelation, functionalization, and solution behaviors of nanodiamonds with ionic liquids.  

PubMed

Detonation nanodiamond particles can be formed a gel with ionic liquids, which can easily be fabricated. The imidazolium bromide-functionalized nanodiamond particles are dispersed in ionic liquids with uniform size-distribution. PMID:19753362

Park, Cho-Long; Jee, Ah Young; Lee, Minyung; Lee, Sang-gi

2009-10-01

313

Probing Local Environments in Ionic Liquids  

NASA Astrophysics Data System (ADS)

The polarity and solvation properties were investigated for four ionic liquids with non-aromatic cation. The four ionic liquids studied were: N-methyl-N-butylpyrrolidinium bis(trifluoromethylsulfonyl)-imide (Pyrr14+/NTf2-), N-methyl-N-ethoxyethylpyrrolidinium bis(trifluoromethylsulfonyl)-imide (Pyrr1(202)+/NTf2-), N-methyl-tri-N-butylammonium bis(trifluoromethylsulfonyl) -imide (N1444+/NTf2-) and N-hexyl-tri-N-butylammonium bis(trifluoromethylsulfonyl) -imide (N6444+/NTf2-). The ammonium based ILs exhibit slightly higher polarity than pyrrolidinium based ILs. The solvation dynamics of the fluorescence probe molecule Coumarin 153 exhibits multi-exponential character in all four ILs. The observed solvation dynamics occur on timescales orders of magnitude longer than for most organic solvents. The reorientational dynamics investigated by method of time-resolved fluorescence anisotropy decay is faster than predicted by hydrodynamic theory. The ionic liquid/water interaction were characterized for hydrophobic and water- miscible ionic liquids. The two ionic liquids studied were: 1-butyl-1-methylpyrrolidinium bis(trifluoromethylsulfonyl)amide (Pyrr14+ /NTf 2-) and 1-butyl-1-methylpyrrolidinium Trifloromethylsulfonate (Pyrr14+/OTf-). The concentration dependence of water proton chemical shift deltaH2O reveals different water-anion interaction in these two ILs. The diffusion properties were investigated in the system IL/water by pulse gradient DOSY experiments. The diffusional behavior of cations and anions is very similar whereas water exhibits anomalously high diffusion rate. The diffusional properties of water are different in two ILs. The ratio D H2O / Dcation is higher for more hydrophobic Pyrr14 + /NTf2- that confirms weaker water-anion interaction in this liquid.

Fadeeva, Tatiana A.

314

Ionic Transport in Liquid Silicates  

Microsoft Academic Search

OME uncertainty exists concerning the presence of semi­ conduction in the electric conduction of liquid silicates. This may be resolved only by measurements of the applicability of Faraday's Laws to the electric transport processes in the melt. Such measurements are considered to be difficult at 800°C in liquid salts.' A method has been devised in these laboratories whereby the oxygen

J. O'M. Bockris; J. A. Kitchener; A. E. Davies

1951-01-01

315

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

316

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

317

Temperature dependence of interactions between stable piperidine-1-yloxyl derivatives and an ionic liquid.  

PubMed

2,2,6,6-Tetramethylpiperidine-1-yloxyl derivatives substituted with either hydrogen bonding [-OH, -OSO(3)H] or ionic [-OSO(3) (-)Na(+), -OSO(3) (-)K(+), N(+)(CH(3))(3)I(-), N(+)(CH(3))(3) N(-)(SO(2)-CF(3))(2)] substituents are investigated in 1-butyl-3-methylimidazolium tetrafluoroborate over a wide temperature range covering both glassy and viscous states. The Vogel-Fulcher-Tammann equation describes the temperature dependence of the ionic liquid viscosity. Quantum chemical calculations of the spin probes at the UB3LYP/6-311(2d,p++) level are done to describe the dependence of the spin density on nitrogen on the substitution pattern of the 4-position of the probe. The results of these calculations are also used to understand the experimental results obtained by applying the Spernol-Gierer-Wirtz theory to analyze the viscosity dependence of the rotational correlation time of the spin probes. Significant differences are found between 2,2,6,6-tetramethylpiperidine-1-yloxyl and its derivatives containing substituents that are able to form hydrogen bonds with the ionic liquid. Moreover, derivatives substituted with ionic groups at the 4-position have a large effect on temperature-induced solvent viscosity, as this is particularly dependent on the nature of the substituent at the 4-position. These dependencies include the temperature region that can be used to describe interactions between the spin probes and the ionic liquid, diffusion into the free volume during non-activated (neutral spin probes) and activated (charged spin probes) processes. Additional parameters are the radii of the ionic liquid and the spin probes, which are calculated and measured approximately. In addition, the temperature dependence of the isotropic hyperfine coupling constants of the spin probes results in information about the micropolarity of the ionic liquid. At room temperature, this is comparable to that of the solvent dimethylsulfoxide. PMID:18470856

Strehmel, Veronika; Rexhausen, Hans; Strauch, Peter; Görnitz, Eckhard; Strehmel, Bernd

2008-06-23

318

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

PubMed Central

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

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

2011-01-01

319

Binding energies of CO2 with some ionic liquids  

NASA Astrophysics Data System (ADS)

Room temperature ionic liquids (RTILs), a novel class of materials with negligible vapor pressures and potentiality as benign solvents, may be an ideal chemical for carbon dioxide (CO2) gas sequestration. Ab initio computational modeling was used to investigate the molecular interactions of simple RTIL anions hexafluorophosphate (PF6^-) and tetrafluoroborate (BF4^-) with CO2. Electronic potential energy surface (PES) scans of a comprehensive sampling of 1:1 anion-CO2 orientations were computed using Spartan '02 with Dunning's correlation consistent basis sets. Qualitatively, the PES scans yielded deeper, more numerous and radially closer active sites surrounding BF4^- anion as compared with the PF6^- anion. Quantitatively, the binding energies of 17.87 kJ/mol and 25.24 kJ/mol were extracted from the identified global energy minima for the PF6^- and BF4^- systems, respectively. The smaller BF4^- anion was concluded to bind more strongly to the CO2. However, literature-reported experimental Henry's law constants for CO2 dissolved in imidizolium based RTILs show greater gas solvation in the PF6^- system. The discrepancy between the energetics calculation results and the experimental solvation data will be discussed.

Eucker, William; Bendler, John

2007-03-01

320

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

321

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

322

Twin-peaks absorption spectra of excess electron in ionic liquids  

NASA Astrophysics Data System (ADS)

The solvated electron in room temperature ionic liquids (RTILs) has been the subject of several investigations and several reports exist on its nature and absorption spectrum. These studies concluded that the solvated electron exhibits an absorption spectrum peaking in the 1000–1400 nm region; a second absorption band peaking in the UV region has been assigned to the hole or dication radicals simultaneously formed in the system. Here we report on the fate of the excess electron in the ionic liquid 1-butyl-1-methylpyrrolidinium bis(trifluoromethylsulfonyl)imide, P14+/NTf2? using nanosecond pulse radiolysis. Scavenging experiments allowed us to record and disentangle the complex spectrum measured in P14+/NTf2?. We identified a bi-component absorption spectrum, due to the solvated electron, the absorption maxima located at 1080 nm and around 300 nm, as predicted by previous ab-initio molecular dynamics simulations for the dry excess electron. We also measured the spectra using different ionic liquids and confirmed the same feature of two absorption peaks. The present results have important implications for the characterization of solvated electrons in ionic liquids and better understanding of their structure and reactivity.

Musat, Raluca M.; Kondoh, Takafumi; Yoshida, Yoichi; Takahashi, Kenji

2014-07-01

323

Electrofluorochromism in ?-conjugated ionic liquid crystals  

NASA Astrophysics Data System (ADS)

Materials in which photoluminescence is modulated by redox processes are known as electrofluorochromic. Intrinsically switchable fluorophores, incorporating both redox and fluorescent moieties, could be ideal electrofluorochromic materials if they possess high fluorescence quantum yields in at least one of their redox states. Fluorescent liquid crystals with redox active centres could combine the above requirements with the advantage to work in bulk anisotropic phases. However, electrofluorochromic liquid crystals have not been reported yet because their synthesis is challenging due to aggregation-caused fluorescent quenching. Here we show the first examples of electrofluorochromic ?-conjugated ionic liquid crystals based on thienoviologens. These ordered materials, combining ionic and electronic functions, are highly fluorescence in the bulk state (quantum yield>60%). Their direct electrochemical reduction leads to fast and reversible bulk electrofluorochromic response in both columnar and smectic phases allowing for fluorescence intensity modulation and colour tuning.

Beneduci, Amerigo; Cospito, Sante; La Deda, Massimo; Veltri, Lucia; Chidichimo, Giuseppe

2014-01-01

324

Molecular dynamics simulation of imidazolium-based ionic liquids. II. Transport coefficients.  

PubMed

A systematic molecular dynamics study is performed to determine the dynamics and transport properties of 12 room-temperature ionic liquids family with 1-alkyl-3-methylimidazolium cation, [amim](+) (alkyl = methyl, ethyl, propyl, and butyl), with counterions, PF(6)(-), NO(3)(-), and Cl(-). The goal of the work is to provide molecular level understanding of the transport coefficients of these liquids as guidance to experimentalists on choosing anion and cation pairs to match required properties of ionic liquid solvents. In the earlier paper (Part I), we characterized the dynamics of ionic liquids and provided a detailed comparison of the diffusion coefficients for each ion using the Einstein and Green-Kubo formulas. In this second part, other transport properties of imidazolium salts are calculated, in particular, the electrical conductivity is calculated from the Nernst-Einstein and Green-Kubo formulas. The viscosity is also determined from the Stokes-Einstein relation. The results of the calculated transport coefficients are consistent with the previous computational and experimental studies of imidazolium salts. Generally, the simulations give electrical conductivity lower than experiment while the viscosity estimate is higher than experiment. Within the same cation family, the ionic liquids with the NO(3)(-) counterion have the highest electrical conductivities: sigma[NO(3)](-)>sigma[PF(6)](-)>sigma[Cl](-). The [dmim][X] series, due to their symmetric cationic structure and good packing and the [bmim][X] series due to higher inductive van der Waals interactions of [bmim](+), have the highest viscosities in these ionic liquid series. Our simulations show that the major factors determining the magnitude of the self-diffusion, electrical conductivity, and viscosity are the geometric shape, ion size, and the delocalization of the ionic charge in the anion. PMID:19140627

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

2009-01-01

325

Molecular dynamics simulation of imidazolium-based ionic liquids. II. Transport coefficients  

NASA Astrophysics Data System (ADS)

A systematic molecular dynamics study is performed to determine the dynamics and transport properties of 12 room-temperature ionic liquids family with 1-alkyl-3-methylimidazolium cation, [amim]+ (alkyl=methyl, ethyl, propyl, and butyl), with counterions, PF6-, NO3-, and Cl-. The goal of the work is to provide molecular level understanding of the transport coefficients of these liquids as guidance to experimentalists on choosing anion and cation pairs to match required properties of ionic liquid solvents. In the earlier paper (Part I), we characterized the dynamics of ionic liquids and provided a detailed comparison of the diffusion coefficients for each ion using the Einstein and Green-Kubo formulas. In this second part, other transport properties of imidazolium salts are calculated, in particular, the electrical conductivity is calculated from the Nernst-Einstein and Green-Kubo formulas. The viscosity is also determined from the Stokes-Einstein relation. The results of the calculated transport coefficients are consistent with the previous computational and experimental studies of imidazolium salts. Generally, the simulations give electrical conductivity lower than experiment while the viscosity estimate is higher than experiment. Within the same cation family, the ionic liquids with the NO3- counterion have the highest electrical conductivities: ?[NO3]->?[PF6]->?[Cl]-. The [dmim][X] series, due to their symmetric cationic structure and good packing and the [bmim][X] series due to higher inductive van der Waals interactions of [bmim]+, have the highest viscosities in these ionic liquid series. Our simulations show that the major factors determining the magnitude of the self-diffusion, electrical conductivity, and viscosity are the geometric shape, ion size, and the delocalization of the ionic charge in the anion.

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

2009-01-01

326

Physical and electrochemical properties of 1-(2-hydroxyethyl)-3-methyl imidazolium and N-(2-hydroxyethyl)- N-methyl morpholinium ionic liquids  

Microsoft Academic Search

Various ionic liquids (ILs) were prepared via metathesis reaction from two kinds of 1-(2-hydroxyethyl)-3-methyl imidazolium ([HEMIm]+) and N-(2-hydroxyethyl)-N-methyl morphorinium ([HEMMor]+) cations and three kinds of tetrafluoroborate ([BF4]?), bis(trifluoromethanesulfonyl)imide ([TFSI]?) and hexafluorophosphate ([PF6]?) anions. All the [HEMIm]+ derivatives were in a liquid state at room temperature. In particular, [HEMIm][BF4] and [HEMIm][TFSI] showed no possible melting point from ?150°C to 200°C by

Sun-Hwa Yeon; Ki-Sub Kim; Sukjeong Choi; Huen Lee; Hoon Sik Kim; Honggon Kim

2005-01-01

327

Surface-functionalized ionic liquid crystal-supported ionic liquid phase materials: ionic liquid crystals in mesopores.  

PubMed

The influence of confinement on the ionic liquid crystal (ILC) [C(18)C(1)Im][OTf] is studied using differential scanning calorimetry (DSC), polarized optical microscopy (POM), and diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS). The ILC studied is supported on Si-based powders and glasses with pore sizes ranging from 11 to 50 nm. The temperature of the solid-to-liquid-crystalline phase transition seems mostly unaffected by the confinement, whereas the temperature of the liquid-crystalline-to-liquid phase transition is depressed for smaller pore sizes. A contact layer with a thickness in the order of 2 nm is identified. The contact layer exhibits a phase transition at a temperature 30 K lower than the solid-to-liquid-crystalline phase transition observed for the neat ILC. For applications within the "supported ionic liquid phase (SILP)" concept, the experiments show that in pores of diameter 50 nm a pore filling of ?>0.4 is sufficient to reproduce the phase transitions of the neat ILC. PMID:22069236

Kohler, Florian T U; Morain, Bruno; Weiss, Alexander; Laurin, Mathias; Libuda, Jörg; Wagner, Valentin; Melcher, Berthold U; Wang, Xinjiao; Meyer, Karsten; Wasserscheid, Peter

2011-12-23

328

Stability of alemtuzumab solutions at room temperature  

PubMed Central

Purpose The stability of alemtuzumab concentrations, 6.67 mcg/mL in glass bottles and, 40 mcg/mL, and 120 mcg/mL in polyolefin containers when stored at room temperature was evaluated. Methods Triplicate solutions of alemtuzumab in 0.9% sodium chloride were prepared in either glass bottles or polyolefin containers and stored at room temperature under normal fluorescent lightening conditions. The solutions were analyzed by a stability-indicating high-performance liquid chromatography assay at 0, 8, 14, and 24 hours after preparation. The pH of the solution was measured and the solution containers were visually inspected at these same time points. Stability was defined as retention of ?90% of the initial alemtuzumab concentration. Results All solutions retained over 90% of their initial concentration with no significant change over the time period studied. The more dilute solution, 6.67 mcg/mL showed some degradation down to 91% of the initial concentration whereas the other concentrations showed greater than 99% over the 24 hour period. The pH of the solutions varied by concentration, but did not change significantly over 24 hours for each concentration studied. No particles were detected in any solution by visual inspection. Conclusion Alemtuzumab concentrations of 6.67 mcg/mL in glass bottles and, 40 mcg/mL, and 120 mcg/mL in polyolefin containers are stable for at least 24 hours at room temperature.

Goldspiel, Justin T.; Goldspiel, Barry R.; Grimes, George; Yuan, Peng; Potti, Gopal

2013-01-01

329

Ultrafast solvation dynamics of coumarin 153 in imidazolium-based ionic liquids.  

PubMed

The dynamic Stokes shift of coumarin 153 has been measured in two room-temperature ionic liquids, 1-(3-cyanopropyl)-3-methylimidazolium bis(trifluoromethylsulfonyl)imide and 1-propyl-3-methylimidazolium tetrafluoroborate, using the fluorescence up-conversion technique with a 230 fs instrumental response function. A component of about 10-15% of the total solvation shift is found to take place on an ultrafast time scale < 10 ps. The amplitude of this component is substantially less than assumed previously by other authors. The origin of the difference in findings could be partly due to chromophore-internal conformational changes on the ultrafast time scale, superimposed to solvation-relaxation, or due to conformational changes of the chromophore ground state in polar and apolar environments. First three-pulse photon-echo peak-shift experiments on indocyanine green in room-temperature ionic liquids and in ethanol indicate a difference in the inertial component of the early solvent relaxation of <100 fs. PMID:16737250

Lang, Bernhard; Angulo, Gonzalo; Vauthey, Eric

2006-06-01

330

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

331

Ionic Conductivity of Solid and Liquid LiAlCl4.  

National Technical Information Service (NTIS)

The electrical conductivity of lithium chloroaluminate has been investigated in the temperature range between room temperature and 180 C. It is molten above 145 C. The conduction is practically purely ionic and is attributed to the transport of lithium io...

W. Weppner R. A. Huggins

1976-01-01

332

Voltammetric behavior of microparticles and thin films of neo-pentyl-ferrocene-based polyester (PmFB): Manipulation of anion uptake at the ionic liquid\\/aqueous electrolyte interface  

Microsoft Academic Search

Voltammetric oxidation of electrodes modified with microparticles and thin films of polymethylferrocene-4,4?-biphenyl dicarboxylate (PmFB) polyester has been undertaken in various room temperature ionic liquids (RTILs), aqueous media, and at the ionic liquid\\/aqueous electrolyte interface. In all cases only one redox process, corresponding to the reversible one-electron oxidation of the ferrocenyl (Fc0\\/+) sites in the PmFB polyester, is observed. The findings

Ayman Nafady

2009-01-01

333

Synthetic organic electrochemistry in ionic liquids: the viscosity question.  

PubMed

Ionic liquids are obvious candidates for use in electrochemical applications due to their ionic character. Nevertheless, relatively little has been done to explore their application in electrosynthesis. We have studied the Shono oxidation of arylamines and carbamates using ionic liquids as recyclable solvents and have noted that the viscosity of the medium is a major problem, although with the addition of sufficient co-solvent, good results and excellent recovery and recycling of the ionic liquid can be achieved. PMID:21769062

Bornemann, Steven; Handy, Scott T

2011-01-01

334

Checkerboard self-patterning of an ionic liquid film on mercury.  

PubMed

Å-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 Å-resolution x-ray study of a Langmuir film of an RTIL on mercury. At low (high) coverage [90 (50) Å2/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. PMID:21668201

Tamam, L; Ocko, B M; Reichert, H; Deutsch, M

2011-05-13

335

Electrochemical biosensing platform based on amino acid ionic liquid functionalized graphene for ultrasensitive biosensing applications.  

PubMed

In this study, a facile non-covalent method was developed for preparing water-soluble graphene with excellent electronic conductivity. Room temperature ionic liquids (ILs) with high ionic conductivity were used for the non-covalent surface functionalization of graphene through ?-? stacking interactions. Compared to other ILs used, amino acid ionic liquids (AAILs) were found to be the most effective for improving the dispersion of graphene in water phase. Electrochemical and spectroscopic results confirmed that the obtained AAIL functionalized GR can retain the excellent electronic conductivity of pristine graphene without damaging the graphene lattice. The obtained water-soluble graphene (GR-AAIL) was exemplified to fabricate an electrochemical biosensor using tyrosinase as a model enzyme, and the sensitivity (12,600mAcm(-2)M(-1)) of GR-AAIL based biosensor was about 17 times higher than that of graphene oxide and other nanomaterial based biosensor, displaying its unprecedented high sensitivity for biosensing. The detection limit for catechol (one important environmental pollutant) reached as low as 8nM with a response time of 3s and a linear range from 25nM to 11,100nM. The AAIL-GR based biosensor also demonstrated good reproducibility, repeatability, selectivity, long-term stability and high recovery for catechol detection. Amino acid ionic liquid functionalized graphene proves to be a robust and versatile electrochemical biosensing platform for fabricating biosensors with excellent performance. PMID:24997366

Lu, Xianbo; Wang, Xue; Jin, Jing; Zhang, Qing; Chen, Jiping

2014-12-15

336

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

337

Ionic liquid sensitized fluorescence determination of four isoquinoline alkaloids  

Microsoft Academic Search

The fluorescence spectra of berberine, palmatine, jatrorrhizine, and coptisine in ionic liquids were studied and found to increase significantly in ionic liquids, with [C8MIM][PF6] having the greatest increase. Further studies showed that these drugs could be extracted from an aqueous solution by [C8MIM][PF6] using the temperature-assisted ionic liquid dispersive liquid phase microextraction method. The enrichment factors were 81.8–82.3, and the

Hao Wu; Li-bing Zhang; Li-ming Du

2011-01-01

338

Room temperature electrodeposition of molybdenum sulfide for catalytic and photoluminescence applications.  

PubMed

An elegant method for the electrodeposition of MoS2 thin films using room temperature ionic liquids (RTIL) as an electrolyte was developed. Simple molecular precursors of Mo and S were added in different concentrations to tune the composition and deposition process. The electrodeposition of MoS2 was confirmed with both Raman spectroscopy and XPS. Analysis showed that the electrodeposited MoS2 films form a flower shape morphology with edge active sites that promote the hydrogen evolution reaction (HER). Furthermore, this technique enables selective tuning of the film thickness and demonstrates high photoluminescence activity with a decrease in the number of layers. PMID:23962095

Murugesan, Sankaran; Akkineni, Arunkumar; Chou, Brendan P; Glaz, Micah S; Vanden Bout, David A; Stevenson, Keith J

2013-09-24

339

Polymer-supported ionic-liquid-like phases (SILLPs): transferring ionic liquid properties to polymeric matrices.  

PubMed

The physico-chemical properties of polymers with ionic-liquid-like moieties covalently bound to their surfaces (SILLPs) have been studied by thermal and spectroscopic techniques, as well as by direct impedance and dielectric measurements, and compared to those of the corresponding bulk ionic liquids. The effective transfer of properties from ionic liquids in solution to the supported species has thereby been demonstrated. The effects of the chemical nature of these tunable "solid solvents" on their macroscopic swelling and microwave heating, as well as the stabilities and activities of different catalytic moieties immobilized on the SILLPs, have been studied. Finally, the experimental effect observed in microwave heating can be directly correlated with the values of tan ? derived from dielectric measurements. PMID:21274940

Sans, Victor; Karbass, Naima; Burguete, M Isabel; Compañ, Vicente; García-Verdugo, Eduardo; Luis, Santiago V; Pawlak, Milena

2011-02-01

340

Ionic Liquids as a Medium for Ionic Chain Polymerizations: An Environmentally Responsible Approach to Macromolecular Synthesis with Controlled Architecture.  

National Technical Information Service (NTIS)

This Short Term Innovation Research proposal set out to explore the possible advantages of using ionic liquids as a medium for ionic polymerizations. The first anionic, living polymerization in an ionic liquid medium was accomplished. Reaction conditions ...

S. Gross

2004-01-01

341

Evaporation from an ionic liquid emulsion.  

PubMed

The conditions during evaporation in a liquid crystal-in-ionic liquid microemulsion (LC/microEm) were estimated using the phase diagram of the system. The equations for selected tie lines were established and the coordinates calculated for the sites, at which the evaporation lines crossed the tie lines. These values combined with the coordinates for the phases connecting the tie lines were used to calculate the amounts and the composition of the fractions of the two phases present in the emulsion during the evaporation. One of the emulsion phases was a lamellar liquid crystal and high energy emulsification would lead to the liquid crystal being disrupted to form vesicles. Such a system tenders a unique opportunity to study the interaction between vesicles and normal micelles, which gradually change to inverse micelles over bi-continuous structures. The amount of vesicles in the liquid phase versus the fraction liquid crystal was calculated for two extreme cases of vesicle core size and shell thickness. The limit of evaporation while retaining the vesicle structure was calculated for emulsions of different original compositions assuming the minimum continuous liquid phase to be 50% of the emulsion. PMID:17207810

Friberg, Stig E

2007-03-15

342

Supramolecular gelators based on benzenetricarboxamides for ionic liquids.  

PubMed

Supramolecular gelators comprising 1,3,5-benzenetricarboxylic acids and amino acid methyl esters (glycine, l-alanine, l-valine, l-leucine, l-methionine, and l-phenylalanine) for ionic liquids were developed. Ten types of ionic liquids were gelated using the above-mentioned gelators at relatively low concentrations. Field emission-scanning electron microscopy and confocal laser scanning microscopy analyses revealed that these gelators self-assembled into an entangled fibrous structure in ionic liquids, leading to the gelation of the ionic liquids. Comparison studies, involving compounds analogous to the gelators, and Fourier transform infrared spectroscopy measurements suggested that hydrogen bonding played a key role in the self-assembly of the gelator molecules. The ionogels displayed reversible thermal transition characteristics and viscoelastic properties typical of a gel. The gelation of the ionic liquids studied under a wide range of gelator concentrations did not affect the intrinsic conductivity of the ionic liquids. PMID:24652194

Ishioka, Yumi; Minakuchi, Nami; Mizuhata, Minoru; Maruyama, Tatsuo

2014-01-22

343

Application of ionic liquid in liquid phase microextraction technology.  

PubMed

Ionic liquids (ILs) are novel nonmolecular solvents. Their unique properties, such as high thermal stability, tunable viscosity, negligible vapor pressure, nonflammability, and good solubility for inorganic and organic compounds, make them excellent candidates as extraction media for a range of microextraction techniques. Many physical properties of ILs can be varied, and the structural design can be tuned to impart the desired functionality and enhance the analyte extraction selectivity, efficiency, and sensitivity. This paper provides an overview of the applications of ILs in liquid phase microextraction technology, such as single-drop microextraction, hollow fiber based liquid phase microextraction, and dispersive liquid-liquid microextraction. The sensitivity, linear calibration range, and detection limits for a range of target analytes in the methods were analyzed to determine the advantages of ILs in liquid phase microextraction. PMID:23002004

Han, Dandan; Tang, Baokun; Lee, Yu Ri; Row, Kyung Ho

2012-11-01

344

[Determination of thermodynamic parameters for ionic liquid 1-hexyl-3-methylimidazolium trifluoromethansulfonate by inverse gas chromatography].  

PubMed

The thermodynamic parameters of ionic liquid 1-hexyl-3-methylimidazolium trifluoromethansulfonate ([HMIM] OTF) were investigated by inverse gas chromatography in the temperature range of 343.15-373.15 K. Eighteen probe solvents were used to calculate the molar enthalpy of sorption, molar enthalpy of mixing at infinite dilution, molar enthalpy of vaporization and the mass fraction activity coefficients. Furthermore, Flory-Huggins interaction parameters, the solubility parameter of the ionic liquid were calculated to judge the interactions between [HMIM] OTF and the 18 probes solvents. The results showed that among the selected solvents, n-C6-9, tetrahydrofuran, diethyl ether, cyclohexane and benzene are the poor solvents for [HMIM] OTF, while dichloromethane, acetone, chloroform, ethyl acetate, carbon tetrachloride, methyl acetate, toluene and methanol are the favorite solvents for [HMIM] OTF. In addition, the solubility parameter of [HMIM] OTF at room temperature (298.15 K), which was obtained by linear extrapolation method, was 20.74 (J/cm3)0.5. This study could be used as a reference to the application and research of the ionic liquids. PMID:24822452

Deng, Lishuang; Wang, Qiang; Zhang, Zhengfang; Tang, Jun

2014-02-01

345

Ionic Liquid Structure-Induced Effects on Organic Reactions  

NASA Astrophysics Data System (ADS)

Understanding the ways in which the constituents of ionic liquids, i.e. the type of cation, its substitution, and the type of anion chosen, interact with reactants is prerequisite to deliberately designing an ionic liquid solvent with optimum performance. Several approaches, including physico-chemical and spectroscopic measurements and computational studies of binary ionic liquid-substrate mixtures have been presented that investigate the strength of interactions.

Stark, Annegret

346

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

347

Effect of the structure of imidazolium cations in [BF 4] ?-type ionic liquids on direct electrochemistry and electrocatalysis of horseradish peroxidase in Nafion films  

Microsoft Academic Search

The direct electrochemistry and bioelectrocatalysis of horseradish peroxidase (HRP) in Nafion films at glassy carbon electrode (GCE) was investigated in three [BF4]?-type room-temperature ionic liquids (ILs) to understand the structural effect of imidazolium cations. The three ILs are 1-ethyl-3-methylimidazolium tetrafluoroborate ([Emim][BF4]), 1-butyl-3-methylimidazolium tetrafluoroborate ([Bmim][BF4]) and 1-hexyl-3-methylimidazolium tetrafluoroborate ([Hmim][BF4]). A small amount of water in the three ILs is indispensable for

Lu Lu; Xirong Huang; Yinbo Qu

2011-01-01

348

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

349

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

350

Highly luminescent and color-tunable salicylate ionic liquids.  

PubMed

High quantum yields of up to 40.5% can be achieved in salicylate-bearing ionic liquids. A range of these ionic liquids have been synthesized and their photoluminescent properties studied in detail. The differences noted can be related back to the structure of the ionic liquid cation and possible interionic interactions. It is found that shifts of emission, particularly in the pyridinium-based ionic liquids, can be related to cation-anion pairing interactions. Facile and controlled emission color mixing is demonstrated through combining different ILs, with emission colors ranging from blue to yellow. PMID:24615781

Campbell, Paul S; Yang, Mei; Pitz, Demian; Cybinska, Joanna; Mudring, Anja-Verena

2014-04-14

351

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

352

The first Cu(I)-mediated nucleophilic trifluoromethylation reactions using (trifluoromethyl)trimethylsilane in ionic liquids.  

PubMed

The new ionic liquids (5a-8a) were used as reaction media for nucleophilic trifluoromethylation reactions of trifluoromethyl(trimethyl)silane with (1) aryl, allyl, benzyl, and alkyl halides in Cu(I)-mediated C-C bond formation reactions, and (2) carbonyl functionalities catalyzed with Ph3P or CsF. In addition, conversion of benzyl bromide as a model compound to benzyl fluoride was examined in using 6a CsF as the fluorinating reagent. The morpholinium-based ionic liquid (6a) stood out as an efficient solvent system comparable to organic solvents and superior to the other new ionic liquids prepared in this work as well as to [bmim]+[PF6]-. Neat reactions of N-methyloxazolidine (1), N-methylmorpholine (2), N-methylimidazole (3) or N-methyltriazole (4) with 2-(2-ethoxyethoxy)ethyl bromide (BrCH2CH2OCH2CH2OCH2CH3, ) or 2-bromoethyl methyl ether (BrCH2CH2OCH3, 10) at 75 or 105 degrees C gave the N-(2-ethoxyethoxy)ethyl- or N-methoxyethyl-substituted oxazolidinium, morpholinium, imidazolium and triazolium quaternary bromides (1a-4a, 1b-4b) which were metathesized with LiN(SO2CF3)2 to form the respective room-temperature liquid bis(trifluoromethanesulfonyl)amides 5a-8a and 5b-8b in high yields with transition or melting points < -78 degrees C as determined by DSC. All of the ionic liquids are thermally stable to > 310 degrees C as determined by thermogravimetric analyses (TGA). Densities range between 1.29 and 1.53 g cm(-3) at 25 degrees C. PMID:15455143

Kim, Jinwi; Shreeve, Jean'ne M

2004-10-01

353

Oxygen Extraction from Regolith Using Ionic Liquids  

NASA Technical Reports Server (NTRS)

An important concern with long-duration manned space travel is the need to furnish enough materials to the vehicle, as well as the crew, for the duration of the mission. By extracting oxygen from the oxides present in regolith, propellant and life support could be supplied to the vehicle and the crew while in space, thereby limiting the amount of supplies needed prior to lift-off. Using a class of compounds known as ionic liquids, we have been able to lower the electrolysis operating temperature from 1600 C (molten oxide electrolysis) to less than 200 C, making this process much more feasible in terms of energy consumption and materials handling. To make this process ready for deployment into space, we have investigated what steps of the process would be affected by the low-gravity environment in space. In the lab, the solubilization of lunar regolith simulant in ionic liquid produces water vapor that is normally distilled out of solution and subsequently electrolyzed for oxygen production. This distillation is not possible in space, so we have tested a method known as pervaporation and have suggested a way this technique could be incorporated into a reactor design.

Barrios, Elizabeth A.; Curreri, Peter A.; Karr, Laurel J.

2011-01-01

354

Toxicity of ionic liquids prepared from biomaterials.  

PubMed

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

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

2014-06-01

355

Boundary layer charge dynamics in ionic liquid-ionic polymer transducers  

NASA Astrophysics Data System (ADS)

Ionic polymer transducers (IPTs), also known as ionic polymer-metal composites, are soft sensors and actuators which operate through a coupling of microscale 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 apply Nernst-Planck/Poisson theory to model charge transport in an ionic liquid IPT by considering a certain fraction of the ionic liquid ions as mobile charge carriers, a phenomenon which is unique to ionic liquid IPTs compared to their water-based counterparts. Numerical simulations are performed using the finite element method to examine how the introduction of another pair of mobile ions affects boundary layer charge dynamics, concentration, and charge density distributions in the electric double layer, and the overall charge transferred and current response of the IPT. Due to interactions with the Nafion ionomer, not all of the ionic liquid ions will function as mobile charge carriers; only a certain fraction will exist as ``free'' ions. The presence of mobile ionic liquid ions in the transducer will increase the overall charge transferred when a voltage is applied, and cause the current in the transducer to decay more slowly. The additional mobile ions also cause the ionic concentration profiles to exhibit a nonlinear dynamic response, characterized by nonmonotonic ionic concentration profiles in space and time. Although the presence of mobile ionic liquid ions increases the overall amount of charge transferred, this additional charge transfer occurs in a somewhat symmetric manner. Therefore, the additional charge transferred due to the ionic liquid ions does not greatly increase the net bending moment of the transducer; in fact, it is possible that ionic liquid ion movement actually decreases the observed bending response. This suggests that an optimal electromechanical conversion efficiency for bending actuation is achieved by using an ionic liquid where only a relatively small fraction of the ionic liquid ions exist as free ions. Conversely, if it is desired to increase the overall amount of charge transferred, an ionic liquid with a large fraction of free ions should be used. These theoretical considerations are found to be in good qualitative agreement with recent experimental results.

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

2011-01-01

356

Visualizing preparation using asymmetrical choline-like ionic liquids for scanning electron microscope observation of non-conductive biological samples.  

PubMed

In this study, we investigated conductivity preparation for scanning electron microscope (SEM) observation that used novel asymmetrical choline-type room temperature ionic liquids (RTIL). By immersion in only an RTIL solution, clear SEM images of several types of biological samples were successfully observed. In addition, we could visualize protozoans using RTILs without any dilution. These results suggested that the asymmetrical choline-type RTILs used in this study are suitable for visualizing of biological samples by SEM. Treatment without the need for dilution can obviate the need for adjusting the RTIL concentration and provide for a rapid and easy conductivity treatment for insulating samples. PMID:24745272

Abe, Shigeaki; Hyono, Atsushi; Kawai, Koji; Yonezawa, Tetsu

2014-03-01

357

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

358

Structural and electrochemical properties of succinonitrile-based gel polymer electrolytes: role of ionic liquid addition.  

PubMed

Experimental studies on the novel compositions of gel polymer electrolytes, comprised of plastic crystal succinonitrile (SN) dispersed with pyrrolidinium and imidazolium-based ionic liquids (ILs) entrapped in a host polymer poly(vinylidine fluoride-co-hexafluoropropylene) (PVdF-HFP), are reported. The gel electrolytes are in the form of free-standing films with excellent mechanical, thermal, and electrochemical stability. The introduction of even a small content (~1 wt %) of ionic liquid (1-butyl-1-methylpyrrolidinium bis(trifluoromethyl-sulfonyl)imide (BMPTFSI) or 1-ethyl-3-methylimidazolium trifluoromethanesulfonate (EMITf) in the PVdF-HFP/SN system (1:4 w/w) enhances the electrical conductivity by 4 orders of magnitude, that is, from ~10(-7) to ~10(-3) S cm(-1) at room temperature. The structural changes due to the entrapment of SN or SN/ILs mixtures and ion-SN-polymer interactions are examined by Fourier transform infrared (FTIR)/Raman spectroscopy, scanning electron microscopy (SEM), X-ray diffraction (XRD), and differential scanning calorimmetry (DSC). Various physicochemical properties and fast ion conduction in the gel polymer membranes show their promising characteristics as electrolytes in different ionic devices including supercapacitors. PMID:23758408

Suleman, Mohd; Kumar, Yogesh; Hashmi, S A

2013-06-20

359

Sorption of imidazolium-based ionic liquids to aquatic sediments  

Microsoft Academic Search

Ionic liquids (ILs) have received much attention as “green” alternatives to traditional solvents because they do not evaporate, eliminating concerns over fugitive emissions. However, if ionic liquids are used in industrial applications, they may enter aquatic systems via effluent, and their fate and transport may be influenced by sorption to sediments. In this study, we conducted batch mixing experiments with

J. J. Beaulieu; J. L. Tank; M. Kopacz

2008-01-01

360

Limited thermal stability of imidazolium and pyrrolidinium ionic liquids  

SciTech Connect

Ionic liquids, with their vast applications, have been touted as being thermally stable to very high temperatures. However, decomposition not detected by standard TGA and NMR techniques are observed with spectroscopic techniques sensitive enough to see small amounts of impurities. Decomposition temperatures of common ionic liquids appear to occur at hundreds of degrees below those temperatures previously reported.

Del Sesto, Rico E [Los Alamos National Laboratory (LANL); Mccleskey, T [Los Alamos National Laboratory (LANL); Macomber, Clay [Los Alamos National Laboratory (LANL); Ott, Kevin [Los Alamos National Laboratory (LANL); Koppisch, Andrew [Los Alamos National Laboratory (LANL); Baker, Gary A [ORNL; Burrell, Anthony K [ORNL

2009-01-01

361

Advances in chiral ionic liquids derived from natural amino acids  

Microsoft Academic Search

Ionic liquids (ILs) possess a number of unique properties; hence they have received much interest as green media for synthesis, analysis, catalysis, separation, and energy provision. More recently, chiral ionic liquids (CILs), which are derived from natural amino acids with chirality, biodegradability, reduced toxicity, and high biocompatibility, have also attracted interest. This report provides an overview of the design, synthesis,

Xuewei Chen; Xuehui Li; Aixi Hu; Furong Wang

2008-01-01

362

Structure and magnetic behavior of transition metal based ionic liquids  

SciTech Connect

A series of ionic liquids containing different paramagnetic anions have been prepared and all show paramagnetic behavior with potential applications for magnetic and electrochromic switching as well as novel magnetic transport; also, the tetraalkylphosphonium-based ionic liquids reveal anomalous magnetic behavior.

Del Sesto, Rico E [Los Alamos National Laboratory (LANL); Mccleskey, T [Los Alamos National Laboratory (LANL); Burrell, Anthony K [ORNL; Baker, Gary A [ORNL; Thompson, Joe D. [Los Alamos National Laboratory (LANL); Scott, Brian L. [Los Alamos National Laboratory (LANL); Wilkes, John S [United States Air Force Academy (USAFA), Colorado; Williams, Peg [United States Air Force Academy (USAFA), Colorado

2008-01-01

363

The Hildebrand Solubility Parameters of Ionic Liquids--Part 2  

PubMed Central

The Hildebrand solubility parameters have been calculated for eight ionic liquids. Retention data from the inverse gas chromatography measurements of the activity coefficients at infinite dilution were used for the calculation. From the solubility parameters, the enthalpies of vaporization of ionic liquids were estimated. Results are compared with solubility parameters estimated by different methods.

Marciniak, Andrzej

2011-01-01

364

Intramolecular electron transfer within a covalent, fixed-distance donor-acceptor molecule in an ionic liquid.  

PubMed

Intramolecular photoinduced charge separation and recombination within the donor-acceptor molecule 4-(N-pyrrolidino)naphthalene-1,8-imide-pyromellitimide, 5ANI-PI, are studied using ultrafast transient absorption spectroscopy in the room-temperature ionic liquid, 1-ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)amide [EMIM][Tf2N]. The rate constants of both photoinduced charge separation and charge recombination for 5ANI-PI in [EMIM][Tf2N] are comparable to those observed in pyridine, which has a static dielectric constant similar to that of [EMIM][Tf2N] but a viscosity that is nearly 2 orders of magnitude lower than that of [EMIM][Tf2N]. The electron-transfer dynamics of 5ANI-PI in [EMIM][Tf2N] are compared to those in pyridine as a function of temperature and are discussed in the context of recently reported ionic liquid solvation studies. PMID:17877391

Lockard, Jenny V; Wasielewski, Michael R

2007-10-11

365

Topological Insulators at Room Temperature  

SciTech Connect

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

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

2010-03-25

366

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

NASA Astrophysics Data System (ADS)

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

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

2006-11-01

367

Chemically sensitive field-effect transistor with polyaniline-ionic liquid composite gate.  

PubMed

A sensing layer for a chemically sensitive field-effect transistor (CHEMFET) based on a composite of camphorsulfonic acid (CSA)-doped polyaniline (PANI) and the room-temperature ionic liquid (IL) 1-butyl-3-methylimidazolium bis(trifluoromethanesulfonyl)-imide, BMI(Tf2N), has been developed and characterized for the sensing of ammonia gas. The work function responses of the cast films with and without IL were analyzed by "stepwise" changes of ammonia gas concentration from 0.5 to 694 ppm in air as a function of the mole fraction of IL to PANI. The PANI x CSA/BMI(Tf2N) layers showed enhanced sensitivities, lower detection limits, and shorter response times. There is experimental evidence that PANI forms a charge-transfer complex with imidazolium cation. PMID:18457415

Saheb, Amir; Josowicz, Mira; Janata, Jirí

2008-06-01

368

Magnetic nanoparticles supported ionic liquids improve firefly luciferase properties.  

PubMed

Ionic liquids as neoteric solvents, microwave irradiation, and alternative energy source are becoming as a solvent for many enzymatic reactions. We recently showed that the incubation of firefly luciferase from Photinus pyralis with various ionic liquids increased the activity and stability of luciferase. Magnetic nanoparticles supported ionic liquids have been obtained by covalent bonding of ionic liquids-silane on magnetic silica nanoparticles. In the present study, the effects of [?-Fe2O3@SiO2][BMImCl] and [?-Fe2O3@SiO2][BMImI] were investigated on the structural properties and function of luciferase using circular dichroism, fluorescence spectroscopy, and bioluminescence assay. Enzyme activity and structural stability increased in the presence of magnetic nanoparticles supported ionic liquids. Furthermore, the effect of ingredients which were used was not considerable on K(m) value of luciferase for adenosine-5'-triphosphate and also K(m) value for luciferin. PMID:24492953

Noori, Ali Reza; Hosseinkhani, Saman; Ghiasi, Parisa; Akbari, Jafar; Heydari, Akbar

2014-03-01

369

High ionicity ionic liquids (HIILs): comparing the effect of ethylsulfonate and ethylsulfate anions.  

PubMed

The subject of ionicity has been extensively discussed in the last decade, due to the importance of understanding the thermodynamic and thermophysical behaviour of ionic liquids. In our previous work, we established that ionic liquids' ionicity could be improved by the dissolution of simple inorganic salts in their milieu. In this work, a comparison between the thermophysical properties of two binary systems of ionic liquid + inorganic salt is presented. The effect of the ammonium thiocyanate salt on the ionicity of two similar ionic liquids, 1-ethyl-3-methylimidazolium ethylsulfonate and ethylsulfate, is investigated in terms of the related thermophysical properties, such as density, viscosity and ionic conductivity in the temperature range 298.15-323.15 K. In addition, spectroscopic (NMR and Raman) and molecular dynamic studies were conducted in order to better understand the interactions that occur at a molecular level. The obtained results reveal that although the two anions of the ionic liquid exhibit similar chemical structures, the presence of one additional oxygen in the ethylsulfate anion has a major impact on the thermophysical properties of the studied systems. PMID:24061089

Oliveira, Filipe S; Pereiro, Ana B; Araújo, João M M; Bernardes, Carlos E S; Canongia Lopes, José N; Todorovic, Smilja; Feio, Gabriel; Almeida, Pedro L; Rebelo, Luís P N; Marrucho, Isabel M

2013-11-01

370

Bioanalytical separation and preconcentration using ionic liquids.  

PubMed

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

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

2013-09-01

371

Intermolecular vibrations and fast relaxations in supercooled ionic liquids  

NASA Astrophysics Data System (ADS)

Short-time dynamics of ionic liquids has been investigated by low-frequency Raman spectroscopy (4 < ? < 100 cm-1) within the supercooled liquid range. Raman spectra are reported for ionic liquids with the same anion, bis(trifluoromethylsulfonyl)imide, and different cations: 1-butyl-3-methylimidazolium, 1-hexyl-3-methylimidazolium, 1-butyl-1-methylpiperidinium, trimethylbutylammonium, and tributylmethylammonium. It is shown that low-frequency Raman spectroscopy provides similar results as optical Kerr effect (OKE) spectroscopy, which has been used to study intermolecular vibrations in ionic liquids. The comparison of ionic liquids containing aromatic and non-aromatic cations identifies the characteristic feature in Raman spectra usually assigned to librational motion of the imidazolium ring. The strength of the fast relaxations (quasi-elastic scattering, QES) and the intermolecular vibrational contribution (boson peak) of ionic liquids with non-aromatic cations are significantly lower than imidazolium ionic liquids. A correlation length assigned to the boson peak vibrations was estimated from the frequency of the maximum of the boson peak and experimental data of sound velocity. The correlation length related to the boson peak (~19 A?) does not change with the length of the alkyl chain in imidazolium cations, in contrast to the position of the first-sharp diffraction peak observed in neutron and X-ray scattering measurements of ionic liquids. The rate of change of the QES intensity in the supercooled liquid range is compared with data of excess entropy, free volume, and mean-squared displacement recently reported for ionic liquids. The temperature dependence of the QES intensity in ionic liquids illustrates relationships between short-time dynamics and long-time structural relaxation that have been proposed for glass-forming liquids.

Ribeiro, Mauro C. C.

2011-06-01

372

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 (CF.sub.3SO.sub.3.sup.-), bis(trifluoromethylsulfonyl)imide ((CF.sub.3SO.sub.2).sub.2N.sup.-), bis(perfluoroethylsulfonyl)imide ((CF.sub.3CF.sub.2SO.sub.2).sub.2N.sup.-) and tris(trifluoromethylsulfonyl)methide ((CF.sub.3SO.sub.2).sub.3C.sup.-). Electroluminescent, electrochromic and photoelectrochromic devices with nanostructured electrodes include ionic liquids with bifunctional redox dyes. Some of the electrolyte solutions color to red when devices employing the solutions are powered, leading to red or neutral electrooptic devices.

Burrell, Anthony K. (Los Alamos, NM); 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)

2008-11-11

373

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 (CF.sub.3SO.sub.3.sup.-), bis(trifluoromethylsulfonyl)imide ((CF.sub.3SO.sub.2).sub.2N.sup.-), bis(perfluoroethylsulfonyl)imide ((CF.sub.3CF.sub.2SO.sub.2).sub.2N.sup.-) and tris(trifluoromethylsulfonyl)methide ((CF.sub.3SO.sub.2).sub.3C.sup.-). Electroluminescent, electrochromic and photoelectrochromic devices with nanostructured electrodes include ionic liquids with bifunctional redox dyes.

Warner, Benjamin P. (Los Alamos, NM); McCleskey, T. Mark (Los Alamos, NM); Burrell, Anthony K. (Los Alamos, NM)

2006-10-10

374

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 (CF.sub.3SO.sub.3.sup.-), bis(trifluoromethylsulfonyl)imide ((CF.sub.3SO.sub.2).sub.2N.sup.-), bis(perfluoroethylsulfonyl)imide ((CF.sub.3CF.sub.2SO.sub.2).sub.2N.sup.-) and tris(trifluoromethylsulfonyl)methide ((CF.sub.3SO.sub.2).sub.3C.sup.-). Electroluminescent, electrochromic and photoelectrochromic devices with nanostructured electrodes include ionic liquids with bifunctional redox dyes. Some of the electrolyte solutions color to red when devices employing the solutions are powered, leading to red or neutral electrooptic devices.

Burrell, Anthony K. (Los Alamos, NM); 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)

2009-12-15

375

Microwave-assisted synthesis using ionic liquids.  

PubMed

The research and application of green chemistry principles have led to the development of cleaner processes. In this sense, during the present century an ever-growing number of studies have been published describing the use of ionic liquids (ILs) as solvents, catalysts, or templates to develop more environmentally friendly and efficient chemical transformations for their use in both academia and industry. The conjugation of ILs and microwave irradiation as a non-conventional heating source has shown evident advantages when compared to conventional synthetic procedures for the generation of fast, efficient, and environmental friendly synthetic methodologies. This review focuses on the advances in the use of ILs in organic, polymers and materials syntheses under MW irradiation conditions. PMID:19507045

Martínez-Palou, Rafael

2010-02-01

376

Speciation of mercury by ionic liquid-based single-drop microextraction combined with high-performance liquid chromatography-photodiode array detection.  

PubMed

Room temperature ionic liquids can be considered as environmentally benign solvents with unique physicochemical properties. Ionic liquids can be used as extractant phases in SDME, being compatible with chromatographic systems. A single-drop microextraction method was developed for separation and preconcentration of mercury species (MeHg(+), EtHg(+), PhHg(+) and Hg(2+)), which relies on the formation of the corresponding dithizonates and microextraction of these neutral chelates onto a microdrop of an ionic liquid. Afterwards, the separation and determination were carried out by high-performance liquid chromatography with a photodiode array detector. Variables affecting the formation and extraction of mercury dithizonates were optimized. The optimum conditions found were: microextraction time, 20 min; stirring rate, 900 rpm; pH, 11; ionic liquid type, 1-hexyl-3-methylimidazolium hexafluorophosphate ([C(6)MIM][PF(6)]); drop volume, 4 microL; and no sodium chloride addition. Limits of detection were between 1.0 and 22.8 microg L(-1) for the four species of mercury, while the repeatability of the method, expressed as relative standard deviation, was between 3.7 and 11.6% (n=8). The method was finally applied to the determination of mercury species in different water samples. PMID:19203620

Pena-Pereira, Francisco; Lavilla, Isela; Bendicho, Carlos; Vidal, Lorena; Canals, Antonio

2009-04-30

377

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

PubMed

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

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

2012-04-12

378

Thermodynamic properties of ionic liquids-a cluster approach.  

PubMed

We describe a method for calculating thermodynamic properties of ionic liquids by using standard quantum statistical thermodynamics as characterized by ab initio techniques. We review briefly how thermochemical properties for different sized clusters of ionic liquids are calculated by standard ab initio programs. The cluster partition functions allow one to calculate energies, enthalpies and Gibbs energies. Assuming that the ionic liquid exists exclusively as isolated ion-pairs in the gaseous phase and regarding the largest clusters as possible liquid structures, we could estimate vapor pressures, enthalpies of vaporization and entropies of vaporization. For possible boiling points it is shown how they vary with pressure. PMID:18633554

Ludwig, Ralf

2008-08-01

379

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

NASA Astrophysics Data System (ADS)

Quantum cascade lasers coupled directly to unclad silver halide fibers were used to assemble mid-infrared fiber-optics evanescent-wave sensors suitable to measure the chemical composition of simple liquid droplets. Quantum cascade lasers can be designed to emit across a wide range of mid-infrared wavelengths by tailoring the quantum-well structure, and the wavelength can be fine tuned by a thermoelectric cooler. Here, laser wavelengths were chosen which offer the largest absorption contrast between two constituents of a droplet. The laser was coupled to an unclad silver halide fiber, which penetrates through the droplet resting on a hydrophobic surface. For the same liquid composition and droplet size, the transmitted intensity is weaker for a droplet on a 1H,1H,2H,2H-perfluoro-octyltrichlorosilane coated glass slide than for one on a hexadecanethiol (HDT) coated Au-covered glass slide because of the high reflectivity of the HDT/Au surface at mid-infrared wavelengths. The absorption coefficients of water, glycerol, ?-tocophenol acetate, and squalane were measured by varying the immersion length of the fiber; i.e. the droplet size. A pseudo-Beer-Lambert law fits well with the experimental data. We tested both aqueous liquid mixtures (acetone/water and ethanol/water) and oil-base solutions (n-dodecane/squalane and ?-tocophenol acetate/squalane); ?-tocophenol acetate and squalane are common ingredients of cosmetics, either as active ingredients or for chemical stabilization. Using a 300?m diameter silver halide fiber with a 25mm immersion length, the detection limits are 1 vol.% for ?-tocophenol in squalane and 2 vol.% for acetone in water for laser wavenumbers of 1208 cm-1 and 1363 cm-1, respectively. This work was previously been reported in J. Z. Chen et al. Optics Express 13, 5953 (2005).

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

2005-11-01

380

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

PubMed Central

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

2013-01-01

381

Probing the Structure of Ionic Liquid Surfaces by Rotationally and Electronically Inelastic Scattering of no  

NASA Astrophysics Data System (ADS)

Room temperature ionic liquids (RTIL’s) are a highly diverse class of materials with many potential technological applications. They are candidates for use in advanced electrolytes, green solvents, and supported liquid membranes for CO_2 sequestration. We present studies where inelastic scattering of high or low velocity nitric oxide provides insight into the microscopic structure of these complex surfaces. As an open shell diatomic, jet-cooled NO [^2?1/2(J = 0.5)] features both molecular and electronic collision dynamics as seen by probing scattered rotational and spin-orbit distributions respectively. These studies show substantial variation in degree of rotational and electronic excitation as ionic liquid identity is varied. Also, surface heating is found to have a strong effect on scattered spin-orbit branching, possibly due to the dependence of surface structure on temperature. This is discussed in terms of a picture where the electronic degree of freedom may serve as a sensitive measure of the cationic versus anionic nature of the top few layers of this material.

Ziemkiewicz, M. P.; Zutz, A.; Nesbitt, D. J.

2012-06-01

382

Direct write dispenser printing of a zinc microbattery with an ionic liquid gel electrolyte  

NASA Astrophysics Data System (ADS)

The need for energy dense microbatteries with miniature dimensions has prompted the development of unconventional materials, cell geometries, and processing methods. This work will highlight our materials investigations, deposition methods and the device performance of a printed zinc-manganese dioxide rechargeable microbattery utilizing an ionic liquid gel electrolyte. We have developed a direct write dispenser printing method with the ability to fabricate multilayer structures and precisely deposit and pattern these components onto any substrates. The use of a unique room-temperature ionic liquid swelled into a polymer to form a gel electrolyte with solid-like mechanical strength and liquid-like ion transport properties has enabled the simple fabrication of stacked microbattery structures with the potential to be easily integrated directly onto a microdevice substrate. Initial microbattery tests and cycle behavior are discussed, and after an initial activation of the cathode material, an experimental cell discharge capacity and energy density of 0.98 mA h cm-2 and 1.2 mW h cm-2 were measured, respectively.

Ho, C. C.; Evans, J. W.; Wright, P. K.

2010-10-01

383

Comparative study of bending characteristics of ionic polymer actuators containing ionic liquids for modeling actuation  

NASA Astrophysics Data System (ADS)

Ionic polymer metal composites (IPMCs) that can operate in air have recently been developed by incorporating an ionic liquid in ionic polymers. To understand transduction in these composites, it is important to determine the role of the ionic liquid in the ionic polymer (Nafion®), to identify the counter cation, and to investigate the interaction of IPMCs with water vapor in the air. We used Fourier-transform infrared spectroscopy to analyze three Nafion® membranes, which were soaked in mixtures of water and an ionic liquid (1-ethyl-3-methyl-imidazolium tetrafluoroborate (EMIBF4), 1-buthyl-3-methyl-imidazolium tetrafluoroborate (BMIBF4), and 1-buthyl-3-methyl-imidazolium hexafluorophosphate (BMIPF6)). The results demonstrate that only cations (EMI+ and BMI+) in the ionic liquids are taken into the Nafion® membranes as counter ions and that the water content of the membranes in air is less than ~4% that of Nafion® swollen with water. Based on the experimental results, a transduction model is proposed for an IPMC with an ionic liquid. In this model, bending is caused by local swelling due to the volume effect of the bulky counter cations. This model can explain 30-50% of the experimentally observed bending curvature.

Kikuchi, Kunitomo; Sakamoto, Takumi; Tsuchitani, Shigeki; Asaka, Kinji

2011-04-01

384

Physicochemical Studies of PMR Resins. I: Reaction Mechanism and Kinetics at Room Temperature  

Microsoft Academic Search

The reaction mechanism and kinetics of PMR 15 resin (polymerization of monomeric reactants) were studied at low and room temperature using models thoroughly characterized by nuclear magnetic resonance (1H, 13C liquid and solid state) and liquid chromatography. The results indicate a difference in reactvity of the esters at room temperature and competing reactions that lead to large variations in resin

Marie-Florence Grenier-Loustalot; Philippe Grenier

1991-01-01

385

Shear dynamics of nanoconfined ionic liquids.  

PubMed

We used molecular dynamics simulations to study the structure and shear dynamics of two ionic liquids (ILs) featuring the same cation 1-butyl-3-methyl-imidazolium or [BMIM], paired with bis(trifluoromethanesulphonyl)amide [NTF2] and tetrafluoroborate [BF4] anions, confined between two hydroxylated silica surfaces. The results demonstrate how the shape of IL molecules affects their layering structure at hydroxylated silica surfaces and how the layered structure of nanoconfined liquids determines their dynamical properties at the molecular level. When [BMIM][NTF2] is sheared, larger molecular fluctuations in the inner layers are required to stabilise the system, and the resulting dynamics is irregular. The alternating charged layers in [BMIM][BF4] allow the system to stabilise through smaller oscillations, and the layers appear to shear on top of each other in a laminar fashion. The simulated dynamics explains qualitatively the relative change in viscosity that the two ILs exhibit when confined, as has been observed in previous experiments. PMID:24562163

Canova, Filippo Federici; Matsubara, Hiroki; Mizukami, Masashi; Kurihara, Kazue; Shluger, Alexander L

2014-05-14

386

Soft ionization of thermally evaporated hypergolic ionic liquid aerosols  

SciTech Connect

Isolated ion pairs of a conventional ionic liquid, 1-Ethyl-3-Methyl-Imidazolium Bis(trifluoromethylsulfonyl)imide ([Emim+][Tf2N?]), and a reactive hypergolic ionic liquid, 1- Butyl-3-Methyl-Imidazolium Dicyanamide ([Bmim+][Dca?]), are generated by vaporizing ionic liquid submicron aerosol particles for the first time; the vaporized species are investigated by dissociative ionization with tunable vacuum ultraviolet (VUV) light, exhibiting clear intact cations, Emim+ and Bmim+, presumably originating from intact ion pairs. Mass spectra of ion pair vapor from an effusive source of the hypergolic ionic liquid show substantial reactive decomposition due to the internal energy of the molecules emanating from the source. Photoionization efficiency curves in the near threshold ionization region of isolated ion pairs of [Emim+][Tf2N?] ionic liquid vapor are compared for an aerosol source and an effusive source, revealing changes in the appearance energy due to the amount of internal energy in the ion pairs. The aerosol source has a shift to higher threshold energy (~;;0.3 eV), attributed to reduced internal energy of the isolated ion pairs. The method of ionic liquid submicron aerosol particle vaporization, for reactive ionic liquids such as hypergolic species, is a convenient, thermally ?cooler? source of isolated intact ion pairs in the gas phase compared to effusive sources.

University of California; ERC, Incorporated, Edwards Air Force Base; Air Force Research Laboratory, Edwards Air Force Base; National Synchrotron Radiation Research Center (NSRRC); Koh, Christine J.; Liu, Chen-Lin; Harmon, Christopher W.; Strasser, Daniel; Golan, Amir; Kostko, Oleg; Chambreau, Steven D.; L.Vaghjiani, Ghanshyam; Leone, Stephen R.

2012-03-16

387

Room Temperature Activates Human Blood Platelets  

Microsoft Academic Search

Temperatures ranging from room temperature (20° C) to 42° C are generally not considered to have an activating effect on platelets. However, this assumption is not supported by clinical phenomena that result in hemostatic failure related to hypothermia. In this study, we investigated the effect of temperatures between room temperature (20° C) and 42° C on human blood platelets and

Elisabeth Maurer-Spurej; Gisela Pfeiler; Norbert Maurer; Helmut Lindner; Otto Glatter; Dana V Devine

2001-01-01

388

Thermal stability, complexing behavior, and ionic transport of polymeric gel membranes based on polymer PVdF-HFP and ionic liquid, [BMIM][BF4].  

PubMed

PVdF-HFP + IL(1-butyl-3-methylimidazolium tetrafluoroborate; [BMIM][BF(4)]) polymeric gel membranes containing different amounts of ionic liquid have been synthesized and characterized by X-ray diffraction, scanning electron microscopy, Fourier transform infrared (FTIR), differential scanning calorimetry, thermogravimetric analysis (TGA), and complex impedance spectroscopic techniques. Incorporation of IL in PVdF-HFP polymer changes different physicochemical properties such as melting temperature (T(m)), thermal stability, structural morphology, amorphicity, and ionic transport. It is shown by FTIR, TGA (also first derivative of TGA, "DTGA") that IL partly complexes with the polymer PVdF-HFP and partly remains dispersed in the matrix. The ionic conductivity of polymeric gel membranes has been found to increase with increasing concentration of IL and attains a maximum value of 1.6 × 10(-2) S·cm(-1) for polymer gel membrane containing 90 wt % IL at room temperature. Interestingly, the values of conductivity of membranes with 80 and 90 wt % of IL were higher than that of pure IL (100 wt %). The polymer chain breathing model has been suggested to explain it. The variation of ionic conductivity with temperature of these gel polymeric membranes follows Arrhenius type thermally activated behavior. PMID:23167848

Shalu; Chaurasia, S K; Singh, R K; Chandra, S

2013-01-24

389

Tribological properties of Ti-doped DLC coatings under ionic liquids lubricated conditions  

NASA Astrophysics Data System (ADS)

In this paper, titanium doped diamond-like carbon (Ti-DLC) coatings were prepared onto AISI 52100 steel substrates using medium frequency magnetic sputtering process, and were analyzed using the Raman and transmission electron microscope (TEM). Two kinds of 1,3-dialkyl imidazolium ionic liquids (ILs) were synthesized and evaluated as lubricants for Ti-DLC/steel contacts at room temperature, and PFPE as comparison lubricant. The tribological properties of the ILs were investigated using a ball-on-disk type UMT reciprocating friction tester. The results indicated that the ILs have excellent friction-reducing properties, the friction coefficient kept at a relatively stable value of 0.07-0.06, which was reduced approximately by 47% compared with perfluoropolyether (PFPE). The worn surfaces of Ti-DLC coatings were observed and analyzed using a MICROXAM-3D non-contact surface profiler, scanning electron microscope (SEM) and X-ray photoelectron spectroscopy (XPS). The Ti-DLC coatings using ionic liquids lubricating systems are considered as potential lubricating system in vacuum and space moving friction pairs.

Feng, Xin; Xia, Yanqiu

2012-01-01

390

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

NASA Astrophysics Data System (ADS)

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

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

391

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

NASA Astrophysics Data System (ADS)

Effect of a room temperature ionic liquid (RTIL) and water on the ultrafast excited state proton transfer (ESPT) of pyranine (8-hydroxypyrene-1,3,6-trisulfonate, HPTS) inside a microemulsion is studied by femtosecond up-conversion. The microemulsion consists of the surfactant, triton X-100 (TX-100) in benzene (bz) and contains the RTIL, 1-pentyl-3-methyl-imidazolium tetrafluoroborate ([pmim] [BF4]) as the polar phase. In the absence of water, HPTS undergoes ultrafast ESPT inside the RTIL microemulsion (RTIL/TX-100/bz) and the deprotonated form (RO-) exhibits three rise components of 0.3, 14, and 375 ps. It is proposed that in the RTIL microemulsion, HPTS binds to the TX-100 at the interface region and participates in ultrafast ESPT to the oxygen atoms of TX-100. On addition of water an additional slow rise of 2150 ps is observed. Similar long rise component is also observed in water/TX-100/benzene reverse micelle (in the absence of [pmim] [BF4]). It is suggested that the added water molecules preferentially concentrate (trapped) around the palisade layer of the RTIL microemulsion. The trapped water molecules remain far from the HPTS both in the presence and absence of ionic liquid and gives rise to the slow component (2150 ps) of ESPT. Replacement of H2O by D2O causes an increase in the time constant of the ultraslow rise to 2350 ps.

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

2010-05-01

392

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

PubMed

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

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

2013-06-13

393

An ionic liquid-type carbon paste electrode for electrochemical investigation and determination of calcium dobesilate.  

PubMed

An ionic liquid-type carbon paste electrode (IL-CPE) had been fabricated by replacing non-conductive organic binders with a conductive room temperature ionic liquid, 1-pentyl-3-methylimidazolium hexafluorophosphate (PMIMPF(6)). The electrochemical responses of calcium dobesilate were investigated at the IL-CPE and the traditional carbon paste electrode (T-CPE) in 0.05molL(-1) H(2)SO(4), respectively. The results showed the superiority of IL-CPE to T-CPE in terms of provision of higher sensitivity, faster electron transfer and better reversibility. A novel method for determination of calcium dobesilate was proposed. The oxidation peak current was rectilinear with calcium dobesilate concentration in the range of 8.0x10(-7) to 1.0x10(-4)molL(-1), with a detection limit of 4.0x10(-7)molL(-1) (S/N=3) by differential pulse voltammetry. The proposed method was applied to directly determine calcium dobesilate in capsule and urine samples. PMID:19073121

Zheng, Jianbin; Zhang, Ya; Yang, Pingping

2007-10-31

394

The influence of silica nanoparticles on ionic liquid behavior: a clear difference between adsorption and confinement.  

PubMed

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

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

2013-01-01

395

Molecular dynamics studies on the water mixtures of pharmaceutically important ionic liquid lidocaine HCl.  

PubMed

In this paper the molecular dynamics of a common local-anesthetic drug, lidocaine hydrochloride (LD-HCl), and its water mixtures were investigated. By means of broadband dielectric spectroscopy and calorimetric measurements it was shown that even a small addition of water causes a significant effect on the relaxation dynamics of analyzed protic ionic liquid. Apart from the two well-resolved relaxations (?- and ?-processes) and the ?-mode, identified as the JG-process, observed for anhydrous LD-HCl, a new relaxation peak (?) is visible in the dielectric spectra of aqueous mixtures of this drug. Additionally, the significant effect of the water on the glass transition temperature of LD-HCl was found. The sample characterized with mole fraction of water X(w) = 0.44 reveals the glass transition temperature T(g), 42 K lower than that of anhydrous material (307 K). Finally, it was shown that by amorphization of the hydrochloride salt of lidocaine it is possible to obtain its room temperature ionic liquid form. PMID:22424553

Wojnarowska, Z; Grzybowska, K; Hawelek, L; Swiety-Pospiech, A; Masiewicz, E; Paluch, M; Sawicki, W; Chmielewska, A; Bujak, P; Markowski, J

2012-05-01

396

In situ crystallization of low-melting ionic liquid [BMIM][PF6] under high pressure up to 2 GPa.  

PubMed

To develop a new practical method of purifying and recycling ionic liquids, we performed direct microscopic observations and in situ crystallization of low-melting ionic liquid, 1-butyl-3-methylimidazolium hexafluorophosphate ([BMIM][PF(6)]), in detail by high pressure Raman spectroscopy. Compression of [BMIM][PF(6)] was measured under pressures up to about 2.0 GPa at temperatures 293-353 K by using a high pressure diamond anvil cell (DAC). At room temperature, with pressure increasing, the characteristic bands of [BMIM][PF(6)] displayed nonmonotonic pressure-induced frequency shifts, and [BMIM][PF(6)] experienced the liquid-solid phase transition at about 0.50 GPa. In separate experiments, in situ crystallization of low-melting ionic liquid [BMIM][PF(6)] were also measured at various P-T regions, in order to improve the understanding of its stability limits. Finally, the T versus P phase diagram of [BMIM][PF(6)] was constructed, and it showed that the melting point was an increase function of pressure. It was also indicated that the structure changes in the crystalline and liquid states under high pressure might also be associated with conformational changes in the butyl chain. Pressure-released Raman spectra also showed that the phase transition of [BMIM][PF(6)] was reversible. PMID:20353249

Su, Lei; Li, Min; Zhu, Xiang; Wang, Zheng; Chen, Zhenping; Li, Fangfei; Zhou, Qiang; Hong, Shiming

2010-04-22

397

A supercooled imidazolium iodide ionic liquid as a low-viscosity electrolyte for dye-sensitized solar cells.  

PubMed

A series of allyl-functionalized imidazolium salts are reported, including 1-allyl-3-ethylimidazolium iodide and 1-allyl-3-propylimidazolium iodide, which have melting points close to room temperature and show typical properties of supercooled fluids if heated above their melting points. Their viscosities in the liquid state are considerably lower than the benchmark ionic liquid used in solar cells, viz., 1-propyl-3-methylimidazolium iodide. Electrolytes containing these new liquids provide excellent efficiencies and good stability in dye-sensitized solar cells when subjected to an accelerated-light soaking test at 60 degrees C. The structures of three of the new salts have been established in the solid state by single-crystal X-ray analysis. PMID:17173385

Fei, Zhaofu; Kuang, Daibin; Zhao, Dongbin; Klein, Cedric; Ang, Wee Han; Zakeeruddin, Shaik M; Grätzel, Michael; Dyson, Paul J

2006-12-25

398

Electrokinetics of Correlated Electrolytes and Ionic Liquids  

NASA Astrophysics Data System (ADS)

Perhaps the most basic assumption of classical electrokinetic theory is the mean-field approximation, where the each ion feels only the electric field produced by the mean charge density (via Poisson's equation) rather than the fluctuating Coulomb forces with individual neighbors. Here, we present a simple continuum model for electrostatic correlations between finite-sized ions, which leads to a 4th order modified Poisson equation, convenient for the analysis of electrokinetic phenomena. When the mean-field approximation breaks down, e.g. due to large ion concentrations, large ion valences, and/or nanoscale confinement, the zeta potential loses its significance, and the model predicts that electro-osmotic flows are typically reduced - or even reversed - by correlation effects, compared to the prediction of the Helmholtz-Smoluchowski formula. This may help to explain the over-prediction of induced-charge electro-osmotic flows by classical models. An interesting limit of the model describes electro-osmosis in solvent-free ionic liquids and molten salts, which may be important in energy storage and electroactuation applications.

Storey, Brian; Bazant, Martin

2011-11-01

399

Electropolymerization of polypyrrole by bipolar electrochemistry in an ionic liquid.  

PubMed

Bipolar electrochemistry has been recently explored for the modification of conducting micro- and nanoobjects with various surface layers. So far, it has been assumed that such processes should be carried out in low-conductivity electrolytes in order to be efficient. We report here the first bipolar electrochemistry experiment carried out in an ionic liquid, which by definition shows a relatively high conductivity. Pyrrole has been electropolymerized on a bipolar electrode, either in ionic liquid or in acetonitrile. The resulting polymer films were characterized by scanning electron microscopy and by contact profilometry. We demonstrate that the films obtained in an ionic liquid are thinner and smoother than the films synthesized in acetonitrile. Furthermore, a well-defined band of polypyrrole can be obtained in ionic liquid, in contrast to acetonitrile for which the polypyrrole film is present on the whole anodic part of the bipolar electrode. PMID:24605863

Kong, Shuwei; Fontaine, Olivier; Roche, Jérôme; Bouffier, Laurent; Kuhn, Alexander; Zigah, Dodzi

2014-03-25

400

Hydrolysis of cellulose in SO?H-functionalized ionic liquids.  

PubMed

Influence of acidity and structure of ionic liquids on microcrystalline cellulose (MCC) hydrolysis was investigated. MnCl?-containing ionic liquids (ILs) were efficient catalysts and achieved MCC conversion rates of 91.2% and selectivities for 5-hydroxymethyl furfural (HMF), furfural and levulinic acid (LA) of 45.7%, 26.2% and 10.5%, respectively. X-ray diffractometry indicated that catalytic hydrolysis of MCC in ionic liquids resulted in the changes to MCC crystallinity and transformation of cellulose I into cellulose II. SO?H-functionalized ionic liquids showed higher activities than non-functionalized ILs. The simplicity of the chemical transformation of cellulose provides a new approach for the use this polymer as raw material for renewable energy and chemical industries. PMID:21757338

Tao, Furong; Song, Huanling; Chou, Lingjun

2011-10-01

401

Robust and versatile ionic liquid microarrays achieved by microcontact printing  

NASA Astrophysics Data System (ADS)

Lab-on-a-chip and miniaturized systems have gained significant popularity motivated by marked differences in material performance at the micro-to-nano-scale realm. However, to fully exploit micro-to-nano-scale chemistry, solvent volatility and lack of reproducibility need to be overcome. Here, we combine the non-volatile and versatile nature of ionic liquids with microcontact printing in an attempt to establish a facile protocol for high throughput fabrication of open microreactors and microfluidics. The micropatterned ionic liquid droplets have been demonstrated as electrochemical cells and reactors for microfabrication of metals and charge transfer complexes, substrates for immobilization of proteins and as membrane-free high-performance amperometric gas sensor arrays. The results suggest that miniaturized ionic liquid systems can be used to solve the problems of solvent volatility and slow mass transport in viscous ionic liquids in lab-on-a-chip devices, thus providing a versatile platform for a diverse number of applications.

Gunawan, Christian A.; Ge, Mengchen; Zhao, Chuan

2014-04-01

402

Atomistic simulations of the solid-liquid transition of 1-ethyl-3-methyl imidazolium bromide ionic liquid  

NASA Astrophysics Data System (ADS)

Achieving melting point around room temperature is important for applications of ionic liquids. In this work, molecular dynamics simulations are carried out to investigate the solid-liquid transition of ionic liquid 1-ethyl-3-methyl imidazolium bromide ([emim]Br) by direct heating, hysteresis, void-nucleation, sandwich, and microcanonical ensemble approaches. Variations of the non-bonded energy, density, diffusion coefficient, and translational order parameter of [emim]Br are analyzed as a function of temperature, and a coexisting solid-liquid system is achieved in the microcanonical ensemble method. The melting points obtained from the first three methods are 547 +/- 8 K, 429 +/- 8 K, and 370 +/- 6 K; while for the sandwich method, the melting points are 403 +/- 4 K when merging along the x-axis by anisotropic isothermal-isobaric (NPT) ensemble, 393 +/- 4 K when along the y-axis by anisotropic NPT ensemble, and 375 +/- 4 K when along the y-axis by isotropic NPT ensemble. For microcanonical ensemble method, when the slabs are merging along different directions (x-axis, y-axis, and z-axis), the melting points are 364 +/- 3 K, 365 +/- 3 K, and 367 +/- 3 K, respectively, the melting points we get by different methods are approximately 55.4%, 21.9%, 5.1%, 14.5%, 11.6%, 6.5%, 3.4%, 3.7%, and 4.3% higher than the experimental value of 352 K. The advantages and disadvantages of each method are discussed. The void-nucleation and microcanonical ensemble methods are most favorable for predicting the solid-liquid transition.

Feng, Haijun; Zhou, Jian; Qian, Yu

2011-10-01

403

Silica xerogels and aerogels synthesized with ionic liquids  

Microsoft Academic Search

The synthesis of silica gels with ionic liquids (IL) as either additives or co-solvents is described. The wet gels were either dried by supercritical CO2 or by evaporation to obtain aerogels or xerogels, respectively. The effects of two ionic liquids: 1-butyl-3-methyl imidazolium tetrafluororate (IL1) and 1-butyl-4-methyl pyridinium tetrafluoroborate (IL2), on the structural and textural characteristics of gels were investigated. IL2

Ali Karout; Alain. C. Pierre

2007-01-01

404

Preparation of Cellulose Nanocrystals Using an Ionic Liquid  

Microsoft Academic Search

In this paper cellulose nanocrystals were prepared by treating microcrystalline cellulose with 1-butyl-3-methylimidazolium\\u000a hydrogen sulphate ionic liquid. Cellulose nanocrystals, after separation from ionic liquid, were characterized by X-ray diffraction\\u000a (XRD), Fourier transform infrared (FTIR), Field emission scanning electron microscopy (FESEM) Transmission Electron Microscope\\u000a (TEM) and Thermogravimetric analysis. XRD results showed no changes in type of cellulose after the treatment with

Zakaria Man; Nawshad Muhammad; Ariyanti Sarwono; Mohamad Azmi Bustam; M. Vignesh Kumar; Sikander Rafiq

405

Membrane contactor assisted extraction/reaction process employing ionic liquids  

DOEpatents

The present invention relates to a functionalized membrane contactor extraction/reaction system and method for extracting target species from multi-phase solutions utilizing ionic liquids. One preferred embodiment of the invented method and system relates to an extraction/reaction system wherein the ionic liquid extraction solutions act as both extraction solutions and reaction mediums, and allow simultaneous separation/reactions not possible with prior art technology.

Lin, Yupo J. (Naperville, IL); Snyder, Seth W. (Lincolnwood, IL)

2012-02-07

406

The Pressure–Viscosity Coefficient of Several Ionic Liquids  

Microsoft Academic Search

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

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

2008-01-01

407

Stability of electrochemomechanical strains in polypyrrole films using ionic liquids  

Microsoft Academic Search

Electrochemomechanical strain (ECMS) of conducting polymers, polypyrrole (PPy) films was studied using several kinds of ionic liquids and the mixed solution with organic solvents from the view points of strain and stability. The PPy films, which were electrodeposited from lithium bis(trifluoromethanesulfonyl)imide (LiTFSI), showed porous morphology. The ECMS in the films operated in ionic liquids was less than 5%, demonstrating a

Kentaro Yamato; Kazuo Tominaga; Wataru Takashima; Keiichi Kaneto

2009-01-01

408

Carbon–ionic liquid double-layer capacitors  

Microsoft Academic Search

A series of electrochemical capacitors, based on activated carbon powders (ACP, specific surface area 870 and 2600 m2\\/g) and ionic liquids as electrolytes, were prepared and tested. The ionic liquids consisted of 1-ethyl-3-methyl imidazolium (EMIm+), 1-butyl-3-methyl imidazolium (BMIm+) and 1-methyl-1-propyl pyrrolidinium (BMPy+) cations, as well as of tetrafluoroborate, hexafluorophosphate and bis((trifluoromethyl)sulfonyl) imide anions. A typical capacitor consisted of two electrodes

A. Lewandowski; M. Galinski

2004-01-01

409

Preparation and Application of Ionic Liquid-Modified Stationary Phases in High Performance Liquid Chromatography  

Microsoft Academic Search

Ionic liquid-modified stationary phases are an important class of stationary phase. They have been shown to have a capability of separating various classes of compounds in HPLC. In this review, we focus on the preparation and application of ionic liquid-modified stationary phases in HPLC. First, two common theories of retention mechanism in the ionic liquid-modified stationary phases in HPLC were

Wentao Bi; Jun Zhou; Kyung-Ho Row

2012-01-01

410

Preparation and Application of Ionic Liquid-Modified Stationary Phases in High Performance Liquid Chromatography  

Microsoft Academic Search

Ionic liquid-modified stationary phases are an important class of stationary phase. They have been shown a capability of separating various classes of compounds in HPLC. In this review, we focus on the preparation and application of ionic liquid-modified stationary phases in HPLC. First, two common theories of retention mechanism in the ionic liquid-modified stationary phases in HPLC were discussed. Then,

Jun Zhou; Wentao Bi; Kyung-Ho Row

2011-01-01

411

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

PubMed

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

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

2014-06-23

412

Ionic-liquid-like copolymer stabilized nanocatalysts in ionic liquids I. Platinum catalyzed selective hydrogenation of o-chloronitrobenzene  

Microsoft Academic Search

An ionic-liquid-like copolymer was used to stabilize the platinum nanoclusters in ionic liquids. Catalytic performance was tested by the selective hydrogenation of o-chloronitrobenzene. Platinum catalysts Pt-I (5.1 nm) and Pt-II (1.7 nm) both exhibited excellent activity and selectivity for the reaction and were recycled with the activity and selectivity preserved. An unprecedented total turnover number (>25,900) was obtained on the

Chao-xian Xiao; Han-zhi Wang; Xin-dong Mu; Yuan Kou

2007-01-01