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1-Methyl-1-propyl-pyrrolidinium chloride  

PubMed Central

The aymmetric unit of the title compound, C8H18N+·Cl?, consists of one crystallographically independent 1-methyl-1-propyl­pyrrolidinium cation and one chloride anion, both of which lie in general positions. Minor hydrogen-bonded C—H?Cl inter­actions occur. However, no classical hydrogen bonding is observed. PMID:21201968

Dean, Pamela M.; Pringle, Jennifer M.; MacFarlane, Douglas R.



Study of a Li-air battery having an electrolyte solution formed by a mixture of an ether-based aprotic solvent and an ionic liquid  

NASA Astrophysics Data System (ADS)

Recent studies have clearly demonstrated that cyclic and linear carbonates are unstable when used in rechargeable Li-air batteries employing aprotic solvents mostly due to the cathodic formation of superoxide during the oxygen reduction reaction. In particular, it has been ascertained that nucleophilic attack by superoxide anion radical, O2-rad , at O-alkyl carbon is a common mechanism of decomposition of organic carbonates. Moreover, theoretical calculations showed that ether chemical functionalities are stable against nucleophilic substitution induced by superoxide. Aim of this study is to report on a new electrolyte solution for Li-air battery formed by a mixture of an ether-based aprotic solvent with an ionic liquid (IL). The IL-based electrolyte was obtained by mixing the pure ionic liquid N-methyl-(n-butyl) pyrrolidinium bis(trifluoromethane sulfonyl) imide (here denoted as PYR14TFSI) to a 0.91 M solution of lithium triflate (LiCF3SO3) in tetra ethylene glycol dimethyl etcher (TEGDME). We observed that the presence of IL beneficially affects the kinetics and the reversibility of the oxygen reactions involved at the cathode. The most significant result being a lower overvoltage for the charge reaction, compared to a Li/air cell containing the same electrolyte solution without IL.

Cecchetto, Laura; Salomon, Mark; Scrosati, Bruno; Croce, Fausto



Synthesis and physicochemical characterization of pyrrolidinium based surfactants.  


Three new pyrrolidinium based surfactants were synthesized and characterized as pure aggregate components and in mixtures with 1,2-dimyristoyl-sn-glycero-3-phosphocholine to understand how the molecular structure of the cationic amphiphile and its mole percentage might affect the physicochemical properties of the resulting aggregates. The thermotropic behavior of the mixed liposomes was investigated by differential scanning calorimetry on multilamellar vesicles, whereas their size and surface potential were investigated on large unilamellar vesicles by dynamic laser light scattering and fluorescence experiments, respectively. The presence of either methoxy or hydroxy groups in the positions 3 and 4 of the pyrrolidinium ring as well as the presence of a second alkyl chain on pyrrolidinium nitrogen, controls the aggregates features. PMID:23141699

Bartoloni, Alessandra; Bombelli, Cecilia; Borocci, Stefano; Bonicelli, Maria Grazia; Galantini, Luciano; Giansanti, Luisa; Ierino, Marco; Mancini, Giovanna; Muschietti, Alessandra; Sperduto, Claudio



Physicochemical properties and toxicities of hydrophobicpiperidinium and pyrrolidinium ionic liquids  

SciTech Connect

Some properties are reported for hydrophobic ionic liquids (IL) containing 1-methyl-1-propyl pyrrolidinium [MPPyrro]{sup +}, 1-methyl-1-butyl pyrrolidinium [MBPyrro]{sup +}, 1-methyl-1-propyl piperidinium [MPPip]{sup +}, 1-methyl-1-butyl piperidinium [MBPip]{sup +}, 1-methyl-1-octylpyrrolidinium [MOPyrro]{sup +} and 1-methyl-1-octylpiperidinium [MOPip]{sup +} cations. These liquids provide new alternatives to pyridinium and imidazolium ILs. High thermal stability of an ionic liquid increases safety in applications like rechargeable lithium-ion batteries and other electrochemical devices. Thermal properties, ionic conductivities, viscosities, and mutual solubilities with water are reported. In addition, toxicities of selected ionic liquids have been measured using a human cancer cell-line. The ILs studied here are sparingly soluble in water but hygroscopic. We show some structure-property relationships that may help to design green solvents for specific applications. While ionic liquids are claimed to be environmentally-benign solvents, as yet few data have been published to support these claims.

Salminen, Justin; Papaiconomou, Nicolas; Kumar, R. Anand; Lee,Jong-Min; Kerr, John; Newman, John; Prausnitz, John M.



Electrical conductivity and glass formation in nitrile-functionalized pyrrolidinium bis(trifluoromethylsulfonyl)imide ionic liquids: chain length and odd-even effects of the alkyl spacer between the pyrrolidinium ring and the nitrile group.  


The electrical conductivity of a series of pyrrolidinium bis(trifluoromethylsulfonyl)imide ionic liquids, functionalized with a nitrile (cyano) group at the end of an alkyl chain attached to the cation, was studied in the temperature range between 173 K and 393 K. The glass formation of the ionic liquids is influenced by the length of the alkyl spacer separating the nitrile function from the pyrrolidinium ring. The electrical conductivity and the viscosity do not show a monotonic dependence on the alkyl spacer length, but rather an odd-even effect. An explanation for this behavior is given, including the potential energy landscape picture for the glass transition. PMID:24740743

Leys, Jan; Tripathi, Chandra Shekhar Pati; Glorieux, Christ; Zahn, Stefan; Kirchner, Barbara; Longuemart, Stéphane; Lethesh, Kallidanthiyil Chellappan; Nockemann, Peter; Dehaen, Wim; Binnemans, Koen



Combined measurement of translational and rotational diffusion in quaternary acyclic ammonium and cyclic pyrrolidinium ionic liquids.  


The translational self-diffusion coefficients (D(T)) for a series of tetra-alkyl acyclic ammonium and cyclic pyrrolidinium ionic liquids (ILs) were measured using (1)H pulse field gradient (PFG) NMR spectroscopy over various temperatures. These NMR diffusion results were combined with previously measured rotational diffusion coefficients (D(R)) obtained from (14)N NMR relaxation measurements for the same ILs (Alam, T. M.; et al. J. Phys. Chem. A 2011, 115, 4307- 4316). The D(T)/D(R) ratio was then used to estimate the effective hydrodynamic radius and corresponding volumes without the need to directly measure the viscosities of the ILs. The generality, validity, and performance of using this D(T)/D(R) ratio is discussed and compared to the effective hydrodynamic volumes obtained using classic D(T)/viscosity and D(R)/viscosity relationships. The temperature variation observed for the molecular volumes obtained using the D(T)/D(R) ratio is argued to be a signature for the breakdown or decoupling of the Stokes-Einstein and Stoke-Einstein-Debye relationships in these neat IL systems, consistent with recent molecular dynamic simulations. PMID:23327476

Alam, Todd M; Dreyer, Daniel R; Bielawski, Christopher W; Ruoff, Rodney S



Physico-Chemical Properties and Phase Behaviour of Pyrrolidinium-Based Ionic Liquids  

PubMed Central

A review of the relevant literature on 1-alkyl-1-methylpyrrolidinium-based ionic liquids has been presented. The phase diagrams for the binary systems of {1-ethyl-1-methylpyrrolidinium trifluoromethanesulfonate (triflate) [EMPYR][CF3SO3] + water, or + 1-butanol} and for the binary systems of {1-propyl-1-methylpyrrolidinium trifluoromethanesulfonate (triflate) [PMPYR][CF3SO3] + water, or + an alcohol (1-butanol, 1-hexanol, 1-octanol, 1-decanol)} have been determined at atmospheric pressure using a dynamic method. The influence of alcohol chain length was discussed for the [PMPYR][CF3SO3]. A systematic decrease in the solubility was observed with an increase of the alkyl chain length of an alcohol. (Solid + liquid) phase equilibria with complete miscibility in the liquid phase region were observed for the systems involving water and alcohols. The solubility of the ionic liquid increases as the alkyl chain length on the pyrrolidinium cation increases. The correlation of the experimental data has been carried out using the Wilson, UNIQUAC and the NRTL equations. The phase diagrams reported here have been compared to the systems published earlier with the 1-alkyl-1-methylpyrrolidinium-based ionic liquids. The influence of the cation and anion on the phase behaviour has been discussed. The basic thermal properties of pure ILs, i.e., melting temperature and the enthalpy of fusion, the solid-solid phase transition temperature and enthalpy have been measured using a differential scanning microcalorimetry technique. PMID:20480044

Domanska, Urszula



Pyrrolidinium-based ionic liquids doped with lithium salts: how does li(+) coordination affect its diffusivity?  


We present the characterization of LiX-doped room-temperature ionic liquids (ILs) based on the N-butyl-N-methyl pyrrolidinium (PYR14) cation with two fluorinated anions: (trifluoromethanesulfonyl)-(nonafluorobutanesulfonyl)imide (X?IM14) and bis(pentafluoroethanesulfonyl)imide (X?BETI). The new data are also compared with previous results on PYR14TFSI (bis(trifluoromethanesulfonyl)imide). Their local organization has been investigated via NMR nuclear Overhauser effect (NOE) experiments for {(1)H-(19)F} and {(1)H-(7)Li} that give us details on PYR14(+)/X(-) and PYR14(+)/Li(+) contacts. We confirm the presence of [Li(X)2](-) coordinated species in all systems. The long-range, intermolecular NOEs have been detected and provide information on the ions' organization beyond the first solvation sphere. The ionic conductivity, viscosity and self-diffusion coefficients of the ionic mixtures have also been measured. The activation energies for the diffusion of the individual ions and for the fluidity are compared with those for the pure ILs. Finally, density functional calculations on [Li(BETI)2](-), [Li(IM14)2](-), and [Li(TFSI)2](-) complexes demonstrate that the minimum energy structures for all systems correspond to a tetrahedral coordination of the Li-ion by four oxygen atoms of the anions. Assuming very simple key steps for the Li(+) diffusion process (i.e., the concerted breaking and formation of Li-O bonds or the rearrangement around a tetrahedrally coordinated Li(+)), we calculate activation barriers that agree well with the experimental results (approximately 46 kJ/mol, in all systems). PMID:25368963

Castiglione, Franca; Famulari, Antonino; Raos, Guido; Meille, Stefano V; Mele, Andrea; Appetecchi, Giovanni Battista; Passerini, Stefano



A pyrrolidinium nitrate protic ionic liquid-based electrolyte for very low-temperature electrical double-layer capacitors.  


This study describes the use of the pyrrolidinium nitrate ([Pyrr][NO3]) protic ionic liquid (PIL) in a mixture with gamma butyrolactone (?-BL) as an electrolyte for carbon-based supercapacitors with an operating voltage of 2.0 V and at very low temperature. Thermal and transport properties of this electrolyte were firstly evaluated from -40 °C to 80 °C. The evolution of conductivity with the addition of ?-BL rendered it possible to determine the optimal composition for electrochemical application, with a molar fraction of ?-BL of 0.6. This mixture shows a Newtonian behavior with a low viscosity value of 5 mPa s at 25 °C, and exhibits high conductivity values of up to 65 mS cm(-1) at 80 °C. At the same time, exceptional residual conductivity was measured for this composition at -40 °C (9 mS cm(-1)), thanks to the superionic character of pyrrolidinium nitrate PIL. Electrochemical characterization of this electrolyte demonstrated, at first, a passivation on the aluminum collector, secondly good cycling performances with an activated carbon electrode from 50 °C to -40 °C with capacitance up to 132 F g(-1) at room temperature and a wide voltage window (2.0 V). Finally at very low temperature (-40 °C), this system demonstrates an unprecedented combination of high specific capacitance (up to 117 F g(-1)), and rapid charging-discharging even at high current density, which is very promising for the progress of energy storage systems with environmentally friendly electrolytes at such very low temperatures. PMID:23532057

Anouti, Mérièm; Timperman, Laure



Growth of Gold Nanosheets and Nanopolyhedra in Pyrrolidinium-Based Ionic Liquids: Investigation of the Cation Effect on the Resulting Morphologies  

SciTech Connect

Large gold nanosheets and small gold polyhedra have been successfully synthesized in room-temperature ionic liquids (ILs) by an ionothermal reduction of HAuCl{sub 4} under N{sub 2} atmosphere, without using any additives. The effect of the organic cation on the final morphologies of the gold particles has been studied, and a series of pyrrolidinium-, imidazolium-, and quaternary amine-based ionic liquids have been investigated by scanning electron microscopy (SEM) and X-ray diffraction (XRD) measurements. Our results show that these ILs favor the anisotropic growth of gold by acting as template agents and that only gold microspheres can be obtained with the IL containing a reductive functionality.

Bouvy, Claire [ORNL; Baker, Gary A [ORNL; Yin, Hongfeng [ORNL; Dai, Sheng [ORNL



Rotational and Translational Dynamics of Rhodamine 6G in a Pyrrolidinium Ionic Liquid: A Combined Time-Resolved Fluorescence Anisotropy Decay and NMR Study  

SciTech Connect

NMR spectroscopy and time-resolved fluorescence anisotropy decay (TRFAD) are two of the most commonly used methods to study solute-solvent interactions. However, only a few studies have been reported to date using a combined NMR and TRFAD approach to systematically investigate the overall picture of diffusional and rotational dynamics of both the solute and solvent. In this paper, we combined NMR and TRFAD to probe fluorescent rhodamine dyes in a pyrrolidinium-based room temperature ionic liquid (RTIL), an emergent environmentally-friendly solvent type used in several energy-related applications. A specific interaction of the R6G cation and [Tf2N]- anion was identified, resulting in near-stick boundary condition rotation of R6G in this RTIL. The diffusional rates of the R6G solute and [C4mpyr][Tf2N] solvent derived from 1H NMR suggest the rates are proportional to their corresponding hydrodynamic radii. The 1H and 13C NMR studies of self-rotational dynamics of [C4mpyr][Tf2N] showed that the self-rotational correlation time of [C4mpyr]+ is 47 2 ps at 300 K. At the same temperature, we find that the correlation time for N-CH3 rotation in [C4mpyr]+ is 77 2 ps, comparable to overall molecular reorientation. This slow motion is attributed to properties of the cation structure.

Guo, Jianchang [ORNL; Han, Kee Sung [ORNL; Mahurin, Shannon Mark [ORNL; Baker, Gary A [ORNL; Hillesheim, Patrick C [ORNL; Dai, Sheng [ORNL; Hagaman, Edward {Ed} W [ORNL; Shaw, Robert W [ORNL



Studies on the translational and rotational motions of ionic liquids composed of N-methyl-N-propyl-pyrrolidinium (P13) cation and bis(trifluoromethanesulfonyl)amide and bis(fluorosulfonyl)amide anions and their binary systems including lithium salts  

NASA Astrophysics Data System (ADS)

Room-temperature ionic liquids (RTIL, IL) are stable liquids composed of anions and cations. N-methyl-N-propyl-pyrrolidinium (P13, Py13, PYR13, or mppy) is an important cation and produces stable ILs with various anions. In this study two amide-type anions, bis(trifluoromethanesulfonyl)amide [N(SO2CF3)2, TFSA, TFSI, NTf2, or Tf2N] and bis(fluorosulfonyl)amide [N(SO2F)2, FSA, or FSI], were investigated. In addition to P13-TFSA and P13-FSA, lithium salt doped samples were prepared (P13-TFSA-Li and P13-FSA-Li). The individual ion diffusion coefficients (D) and spin-lattice relaxation times (T1) were measured by H1, F19, and L7i NMR. At the same time, the ionic conductivity (?), viscosity (?), and density (?) were measured over a wide temperature range. The van der Waals volumes of P13, TFSA, FSA, Li(TFSA)2, and Li(FSA)3 were estimated by molecular orbital calculations. The experimental values obtained in this study were analyzed by the classical Stokes-Einstein, Nernst-Einstein (NE), and Stokes-Einstein-Debye equations and Walden plots were also made for the neat and binary ILs to clarify physical and mobile properties of individual ions. From the temperature-dependent velocity correlation coefficients for neat P13-TFSA and P13-FSA, the NE parameter 1-? was evaluated. The ionicity (electrochemical molar conductivity divided by the NE conductivity from NMR) and the 1-? had exactly the same values. The rotational and translational motions of P13 and jump of a lithium ion are also discussed.

Hayamizu, Kikuko; Tsuzuki, Seiji; Seki, Shiro; Fujii, Kenta; Suenaga, Masahiko; Umebayashi, Yasuhiro



In situ electrochemical SFG/DFG study of CN- and nitrile adsorption at Au from 1-butyl-1-methyl-pyrrolidinium bis(trifluoromethylsulfonyl) amide ionic liquid([BMP][TFSA]) containing 4-{2-[1-(2-cyanoethyl)-1,2,3,4-tetrahydroquinolin-6-yl]diazenyl} benzonitrile (CTDB) and K[Au(CN)?].  


In this paper we report an in situ electrochemical Sum-/Difference Frequency Generation (SFG/DFG) spectroscopy investigation of the adsorption of nitrile and CN? from the ionic liquid 1-butyl-1-methyl-pyrrolidinium bis(trifluoromethylsulfonyl) amide ([BMP][TFSA]) containing 4-{2-[1-(2-cyanoethyl)-1,2,3,4-tetrahydroquinolin-6-yl]-diazenyl}benzonitrile (CTDB) at Au electrodes in the absence and in the presence of the Au-electrodeposition process from K[Au(CN)?]. The adsorption of nitrile and its coadsorption with CN? resulting either from the cathodic decomposition of the dye or from ligand release from the Au(I) cyanocomplex yield potential-dependent single or double SFG bands in the range 2,125-2,140 cm?¹, exhibiting Stark tuning values of ca. 3 and 1 cm?¹ V?¹ in the absence and presence of electrodeposition, respectively. The low Stark tuning found during electrodeposition correlates with the cathodic inhibiting effect of CTDB, giving rise to its levelling properties. The essential insensitivity of the other DFG parameters to the electrodeposition process is due to the growth of smooth Au. PMID:22732885

Bozzini, Benedetto; Busson, Bertrand; Gayral, Audrey; Humbert, Christophe; Mele, Claudio; Six, Catherine; Tadjeddine, Abderrahmane



Surface properties of Gemini surfactants with pyrrolidinium head groups.  


Gemini surfactants C(n)-4-(n)PB (where n represents the alkyl chain length of 10, 12, 14 and 16) were synthesized and characterized. Their surface activity, thermodynamic properties, and aggregation behavior were investigated by means of surface tension, electrical conductivity, and steady-state fluorescence. It was found that the Gemini surfactants C(n)-4-(n)PB have superior surface activity to their corresponding monomer surfactants C(n)MPB as expected. Additionally, these compounds have lower cmc and surface tension in comparison with conventional cationic Gemini surfactants m-4-m. Thermodynamic parameters (?G(m)(0),?H(m)(0),T?S(m)(0)) show that the micellization is an entropy driven process with shorter hydrophobic chain lengths but instead is enthalpy driven for longer hydrophobic chain lengths. The effect of the hydrophobic alkyl chain length and the addition of inorganic salt NaBr on the surface activity and micellization are in line with the conventional cationic Gemini surfactants. PMID:22261268

Cai, Bo; Li, Xuefeng; Yang, Yi; Dong, Jinfeng



Magnesium(II) bis(trifluoromethane sulfonyl) imide-based electrolytes with wide electrochemical windows for rechargeable magnesium batteries.  


We present a promising electrolyte candidate, Mg(TFSI)2 dissolved in glyme/diglyme, for future design of advanced magnesium (Mg) batteries. This electrolyte shows high anodic stability on an aluminum current collector and allows Mg stripping at the Mg electrode and Mg deposition on the stainless steel or the copper electrode. It is clearly shown that nondendritic and agglomerated Mg secondary particles composed of ca. 50 nm primary particles alleviating safety concern are formed in glyme/diglyme with 0.3 M Mg(TFSI)2 at a high rate of 1C. Moreover, a Mg(TFSI)2-based electrolyte presents the compatibility toward a Chevrel phase Mo6S8, a radical polymer charged up to a high voltage of 3.4 V versus Mg/Mg(2+) and a carbon-sulfur composite as cathodes. PMID:24559269

Ha, Se-Young; Lee, Yong-Won; Woo, Sang Won; Koo, Bonjae; Kim, Jeom-Soo; Cho, Jaephil; Lee, Kyu Tae; Choi, Nam-Soon



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

Microsoft Academic Search

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

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



Influence of Zn2+ and water on the transport properties of a pyrrolidinium dicyanamide ionic liquid.  


In order to expand our understanding of a potential zinc-based battery electrolyte, we have characterized the physical and transport properties of the ionic liquid (IL) 1-butyl-1-methylpyrrolidinium dicyanamide ([C4mpyr][dca]) containing various levels of both Zn(2+) and H2O. Detailed measurements of density, viscosity, conductivity, and individual anion and cation diffusion coefficients using pulsed-field-gradient (PFG) NMR combined with NMR chemical shifts and spin-lattice relaxation (T1) NMR experiments provide insights into the motion and chemical environment of all molecular species. We find that the various techniques for probing ion transport and dynamics form a coherent picture as a function of electrolyte composition. Zn(2+) addition causes a moderate reduction in the self-diffusion of the IL anion and cation, whereas the addition of H2O increases ion mobility by increasing the liquid's overall fluidity. Temperature-dependent (13)C T1 experiments of the dca carbon analyzed using Bloembergen-Purcell-Pound fits show monotonic slowing of anion dynamics with Zn(2+) addition, suggesting increased Zn(2+)/dca(-) association. T1 experiments show minimal change in the spin-lattice relaxation of cation or anion upon H2O addition, suggesting that H2O is playing no significant role in Zn(2+) speciation. Finally, we employ a novel electrophoretic NMR technique to directly determine the electrophoretic mobility of the C4mpyr cation, which we discuss in the context of impedance-based conductivity measurements. PMID:24712560

Simons, T J; Bayley, P M; Zhang, Z; Howlett, P C; MacFarlane, D R; Madsen, L A; Forsyth, M



Communication: X-ray Scattering from Ionic Liquids with Pyrrolidinium Cations  

SciTech Connect

We report the structure functions obtained from x-ray scattering experiments on a series of four homologous ionic liquids. The ionic liquids are 1-alkyl-1-methylpyrrolidinium cations paired with the bis(trifluoromethylsulfonyl)amide anion, with alkyl chain lengths of n = 4, 6, 8, and 10. The structure functions display two intense diffraction peaks for values of the scattering vector q in the range from 0.6 to 1.5 {angstrom}{sup -1} for all samples. Both diffraction peaks shift to lower values of q for increasing temperature. First sharp diffraction peaks are observed in the structure functions for q < 0.5 {angstrom}{sup -1} for liquids with n = 6, 8, and 10.

C Santos; N Murthy; G Baker; E Castner



'Bucky gel' of multiwalled carbon nanotubes as electrodes for high performance, flexible electric double layer capacitors.  


We report the preparation of a gelled form of multiwalled carbon nanotubes (MWCNTs) with an ionic liquid 1-butyl-1-methyl pyrrolidinium bis(trifluoromethane sulfonyl)imide (BMPTFSI)), referred to as 'bucky gel', to be used as binderless electrodes in electrical double layer capacitors (EDLCs). The characteristics of gelled MWCNTs are compared with pristine MWCNTs using transmission electron microscopy, x-ray diffraction and Raman studies. A gel polymer electrolyte film consisting of a blend of poly(vinylidene fluoride-co-hexafluoropropylene) and BMPTFSI, exhibiting a room temperature ionic conductivity of 1.5 × 10(-3) S cm(-1), shows its suitability as an electrolyte/separator in flexible EDLCs. The performance of EDLCs, assembled with bucky gel electrodes, using impedance spectroscopy, cyclic voltammetry and charge-discharge analyses, are compared with those fabricated with pristine MWCNT-electrodes. An improvement in specific capacitance (from 19.6 to 51.3 F g(-1)) is noted when pristine MWCNTs are replaced by gelled MWCNT-binderless electrodes. Although the rate performance of the EDLCs with gelled MWCNT-electrodes is reduced, the pulse power of the device is sufficiently high (~10.5 kW kg(-1)). The gelled electrodes offer improvements in energy and power densities from 2.8 to 8.0 Wh kg(-1) and 2.0 to 4.7 kW kg(-1), respectively. Studies indicate that the gel formation of MWCNTs with ionic liquid is an excellent route to obtain high-performance EDLCs. PMID:24157648

Singh, Manoj K; Kumar, Yogesh; Hashmi, S A




SciTech Connect

Ionic liquids are often cited for their excellent thermal stability, a key property for their use as solvents and in the chemical processing of biofuels. However, there has been little supporting data on the long term aging effect of temperature on these materials. Imizadolium, quaternary ammonium, pyridinium, and pyrrolidnium-based ionic liquids with the bis(trifluoromethylsulfonyl)imide and bis(perfluoroethylsulfonyl)imide anions were aged for 2520 hours (15 weeks) at 200?C in air to determine the effects of an oxidizing environment on their chemical structure and thermal stability over time. It was found that the minor changes in the cation chemistry could greatly affect the properties of the ILs over time.

Fox, E.



Alkyl Chain Length and Temperature Effects on Structural Properties of Pyrrolidinium-Based Ionic Liquids: A Combined Atomistic Simulation and Small-Angle X-ray Scattering Study.  

SciTech Connect

Molecular dynamics (MD) simulations of 1-alkyl-1-methylpyrrolidinium 12 bis(trifluoromethanesulfonyl)imide ([CnMPy][Tf2N], n = 3, 4, 6, 8, 10) were conducted 13 using an all-atom model. Radial distribution functions (RDF) were computed and structure 14 functions were generated to compare with new X-ray scattering experimental results, 15 reported herein. The scattering peaks in the structure functions generally shift to lower Q 16 values with increased temperature for all the liquids in this series. However, the first sharp 17 diffraction peak (FSDP) in the longer alkyl chain liquids displays a marked shift to higher Q 18 values with increasing temperature. Alkyl chain-dependent ordering of the polar groups and 19 increased tail aggregation with increasing alkyl chain length were observed in the partial pair 20 correlation functions and the structure functions. The reasons for the observed alkyl chain- 21 dependent phenomena and temperature effects were explored.

Li, Song [ORNL] [ORNL; Banuelos, Jose Leo [ORNL] [ORNL; Guo, Jianchang [ORNL] [ORNL; Anovitz, Lawrence {Larry} M [ORNL; Rother, Gernot [ORNL] [ORNL; Shaw, Robert W [ORNL] [ORNL; Hillesheim, Patrick C [ORNL] [ORNL; Dai, Sheng [ORNL] [ORNL; Baker, Gary A [ORNL] [ORNL; Cummings, Peter T [ORNL] [ORNL



FTIR and Raman Study of the LixTiyMn1-yO2 (y = 0, 0.11) Cathodes in Methylpropyl Pyrrolidinium Bis(fluoro-sulfonyl)imide, LiTFSI Electrolyte  

SciTech Connect

This work demonstrates the protective effect of partial titanium substitution in Li{sub x}Ti{sub 0.11}Mn{sub 0.89}O{sub 2} against surface decomposition in room-temperature ionic liquid (RTILs) cells. Raman microscopy and reflectance Fourier transform IR (FTIR) spectroscopy were used to analyze electrodes recovered from cycled Li/Li{sub x}Ti{sub y}Mn{sub 1-y}O{sub 2} (y=0, 0.11) cells containing the 0.5 mol/kg LiTFSI in P{sub 13}FSI RTIL electrolyte. [TFSI=bis(trifluoromethanesulfonyl)imide.] Raman and FTIR spectra of cycled Li{sub x}MnO{sub 2} cathodes showed many distinct bands that can be attributed to both the electrolyte and electrode decomposition products. The thickness of the amorphous porous layer on the Li{sub x}MnO{sub 2} cathode increased during cycling. The surface degradation of Li{sub x}MnO{sub 2} and precipitation of electrolyte decomposition products contributed to the film growth. Improved cycling behavior was observed in cells containing Li{sub x}Ti{sub 0.11}Mn{sub 0.89}O{sub 2}, yet Raman spectroscopy also showed possible surface degradation. The FTIR spectra of cycled Li{sub x}MnO{sub 2} and Li{sub x}Ti{sub 0.11}Mn{sub 0.89}O{sub 2} cathodes displayed bands characteristic for LiSO{sub 3}CF{sub 3} and Li{sub 2}NSO{sub 2}CF{sub 3}, which originate from the reaction of the TFSI anion with traces of water present in the cell.

Hardwick, L.J.; Lucas, I.T.; Doeff, M.M.; Kostecki, R.; Saint, J.A.



Bicyclic imidazolium ionic liquids as potential electrolytes for rechargeable lithium ion batteries  

SciTech Connect

A bicyclic imidazolium ionic liquids, 1-ethyl-2,3-trimethyleneimidazolium bis(tri fluoromethane sulfonyl)imide ([ETMIm][TFSI]), and reference imidazolium compounds, 1-ethyl-3-methylimidazolium bis(trifluoromethane sulfonyl)imide ([EMIm][TFSI]) and 1, 2-dimethyl-3-butylimidazolium bis(trifluoromethane sulfonyl)imide ([DMBIm][TFSI]), were synthesized and investigated as solvents for lithium ion batteries. Although the alkylation at the C-2 position of the imidazolium ring does not affect the thermal stability of the ionic liquids, with or without the presence of 0.5 molar lithium bis(trifluoromethane sulfonyl)imide (LiTFSI), the stereochemical structure of the molecules has shown profound influences on the electrochemical properties of the corresponding ionic liquids. [ETMIm][TFSI] shows better reduction stability than do [EMIm][TFSI] and [DMBIm][TFSI], as confirmed by both linear sweep voltammery (LSV) and theoretical calculation. The Li||Li cell impedance of 0.5M LiTFSI/[ETMIm][TFSI] is stabilized, whereas that of 0.5M LiTFSI/[DMBIm][TFSI] is still fluctuating after 20 hours, indicating a relatively stable solid electrolyte interphase (SEI) is formed in the former. Furthermore, the Li||graphite half-cell based on 0.5M LiTFSI/[BTMIm][TFSI] exhibits reversible capacity of 250mAh g-1 and 70mAh g-1 at 25 C, which increases to 330 mAh g-1 and 250 mAh g-1 at 50 C, under the current rate of C/20 and C/10, respectively. For comparison, the Li||graphite half-cell based on 0.5M LiTFSI/[DMBIm][TFSI] exhibits poor capacity retention under the same current rate at both temperatures.

Liao, Chen [ORNL; Shao, Nan [ORNL; Bell, Jason R [ORNL; Guo, Bingkun [ORNL; Luo, Huimin [ORNL; Jiang, Deen [ORNL; Dai, Sheng [ORNL



Lithium-sulfur batteries based on nitrogen-doped carbon and ionic liquid electrolyte  

SciTech Connect

Nitrogen-doped mesoporous carbon (NC) and sulfur were used to prepare an NC/S composite cathode, which was evaluated in an ionic liquid electrolyte of 0.5 M lithium bis(trifluoromethane sulfonyl)imide (LiTFSI) in methylpropylpyrrolidinium bis(trifluoromethane sulfonyl)imide (MPPY.TFSI) by cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), and cycle testing. To facilitate the comparison, a C/S composite based on activated carbon (AC) without nitrogen doping was also fabricated under the same conditions as those for the NC/S composite. Compared with the AC/S composite, the NC/S composite showed enhanced activity toward sulfur reduction, as evidenced by the early onset sulfur reduction potential, higher redox current density in the CV test, and faster charge transfer kinetics as indicated by EIS measurement. At room temperature under a current density of 84 mA g-1 (C/20), the battery based on the NC/S composite exhibited higher discharge potential and an initial capacity of 1420 mAh g-1 whereas that based on the AC/S composite showed lower discharge potential and an initial capacity of 1120 mAh g-1. Both batteries showed similar capacity fading with cycling due to the intrinsic polysulfide solubility and the polysulfide shuttle mechanism; the capacity fading can be improved by further modification of the cathode.

Sun, Xiao-Guang [ORNL; Wang, Xiqing [ORNL; Mayes, Richard T [ORNL; Dai, Sheng [ORNL



In situ FTIR spectroscopy of the Zn–Br battery bromine storage complex at glassy carbon electrodes  

Microsoft Academic Search

In situ reflection absorption FTIR spectroscopy (in situ FTIR) and small spot X-ray electron emission spectroscopy (XPS) of emersed electrodes were used to examine the electrochemical double layer on glassy carbon (GC) and the anodic storage reactions of the zinc bromine battery which are the formation of a non-aqueous N-methyl-ethyl-pyrrolidinium (MEP+) and\\/or N-methyl-ethyl-morpholinium (MEM+) polybromide phase. Oxidative conversion of the

W Kautek; A Conradi; Ch Fabjan; G Bauer



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

Microsoft Academic Search

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

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



Electron Solvation Dynamics and Reactivity in Ionic Liquids Observed by Picosecond RadiolysisTechniques  

SciTech Connect

On time scales of a nanosecond or less, radiolytically-generated excess electrons in ionic liquids undergo solvation processes and reactions that determine all subsequent chemistry and the accumulation of radiolytic damage. Using picosecond pulse radiolysis detection methods, we observed and quantified the solvation response of the electron in 1-methyl-1-butyl-pyrrolidinium bis(trifluoromethylsulfonyl)amide and used it to understand electron scavenging by a typical solute, duroquinone.

Wishart J. F.; Funston, A.M.; Szreder, T.; Cook, A.R.; Gohdo, M.



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



Development and Characterization of Poly(1-vinylpyrrolidone-co-vinyl acetate) Copolymer Based Polymer Electrolytes  

PubMed Central

Gel polymer electrolytes (GPEs) are developed using poly(1-vinylpyrrolidone-co-vinyl acetate) [P(VP-co-VAc)] as the host polymer, lithium bis(trifluoromethane) sulfonimide [LiTFSI] as the lithium salt and ionic liquid, and 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl) imide [EMImTFSI] by using solution casting technique. The effect of ionic liquid on ionic conductivity is studied and the optimum ionic conductivity at room temperature is found to be 2.14?×?10?6?S?cm?1 for sample containing 25?wt% of EMImTFSI. The temperature dependence of ionic conductivity from 303?K to 353?K exhibits Arrhenius plot behaviour. The thermal stability of the polymer electrolyte system is studied by using thermogravimetric analysis (TGA) while the structural and morphological properties of the polymer electrolyte is studied by using Fourier transform infrared (FTIR) spectroscopy and X-ray diffraction analysis (XRD), respectively.

Sa'adun, Nurul Nadiah; Subramaniam, Ramesh; Kasi, Ramesh



Environmentally-friendly lithium recycling from a spent organic li-ion battery.  


A simple and straightforward method using non-polluting solvents and a single thermal treatment step at moderate temperature was investigated as an environmentally-friendly process to recycle lithium from organic electrode materials for secondary lithium batteries. This method, highly dependent on the choice of electrolyte, gives up to 99?% of sustained capacity for the recycled materials used in a second life-cycle battery when compared with the original. The best results were obtained using a dimethyl carbonate/lithium bis(trifluoromethane sulfonyl) imide electrolyte that does not decompose in presence of water. The process implies a thermal decomposition step at a moderate temperature of the extracted organic material into lithium carbonate, which is then used as a lithiation agent for the preparation of fresh electrode material without loss of lithium. PMID:25170568

Renault, Stéven; Brandell, Daniel; Edström, Kristina



Method for measuring surface temperature  


The present invention relates to a method for measuring a surface temperature using is a fluorescent temperature sensor or optical thermometer. The sensor includes a solution of 1,3-bis(1-pyrenyl)propane within a 1-butyl-1-1-methyl pyrrolidinium bis(trifluoromethylsulfonyl)imide ionic liquid solvent. The 1,3-bis(1-pyrenyl)propane remains unassociated when in the ground state while in solution. When subjected to UV light, an excited state is produced that exists in equilibrium with an excimer. The position of the equilibrium between the two excited states is temperature dependent.

Baker, Gary A. (Los Alamos, NM); Baker, Sheila N. (Los Alamos, NM); McCleskey, T. Mark (Los Alamos, NM)



Sol–gel synthesis of vanadium pentoxide nanoparticles in air- and water-stable ionic liquids  

Microsoft Academic Search

Vanadium pentoxide (V2O5) nanoparticles were synthesized at moderate reaction temperatures by hydrolysis of VO[OCH(CH3)2]3 in two different air- and water-stable ionic liquids with the same anion: 1-butyl-1-methyl pyrrolidinium bis(trifluoromethylsulfonyl)amide\\u000a ([Py1,4]Tf2N) and 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)amide ([EMIM]Tf2N) via the sol–gel method using acetone and isopropanol either as refluxing solvents or as co-solvents. The cation type of\\u000a the ionic liquid affects the crystallinity, morphology,

Mohammad Al Zoubi; Hala K. Farag; Frank Endres



Role of Succinonitrile in a Poly(ethylene oxide)/LiTFSI membrane for lithium batteries  

NASA Astrophysics Data System (ADS)

In designing novel flexible lithium battery membranes, high conductivity, peel strength and processability are the main targets for a successful product. Crystallinity of poly(ethylene oxide) (PEO) and lithium salts represent an obstacle to accomplish each of these specifications. We present a systematic study of ternary phase diagrams of PEO, bis(trifluoromethane) sulfonimide (LiTFSI) and succinonitrile (SCN) (i.e., solid plasticizer/co-solvent) mixtures by using DSC and polarized optical microscopy and map out various coexistence regions bound by the liquidus and solidus lines. The eutectic phase diagram of PEO/SCN system was calculated self-consistently using Flory-Huggins theory in conjunction with Landau-type phase field free energy for crystal solidification. Specific interactions such as hydrogen bonding were examined by FTIR. In lieu of PEO, poly(ethylene glycol) diacrylate (PEGDA) were used to completely eliminate all crystals. Further, photopolymerization of PEGDA affords a solid network containing LiTFSI and SCN that shows promising improvements with a conductivity value of 10-4S/cm at 25 C.

Echeverri, Mauricio; Kyu, Thein



Spectroscopic and DFT studies to understand the liquid formation mechanism in the LiTFSI/acetamide complex system.  


It is interesting that although both lithium bis(trifluoromethane sulfone) imide (LiN(SO2CF3)2, LiTFSI) and acetamide (CH3CONH2) are solid, their mixture is a liquid in an appropriate molar ratio range at room temperature. The liquid formation mechanism of the LiTFSI/acetamide complex has been investigated by FT-IR and FT-Raman spectroscopy. The spectroscopic studies show that the Li+ ions coordinate with the C=O group of acetamide whereas the SO2 group in TFSI- anions interacts with the NH2 group of acetamide via hydrogen bonding. These interactions lead to the breakage of the hydrogen bonds between acetamide molecules and to the dissociation of LiTFSI, resulting in the formation of this molten salt. Furthermore, it has been found that moderate interaction between LiX and RCONH2 (R = -NH2, -CH3 and -CF3) is favorable for forming a LiX/RCONH2 molten salt system with low eutectic temperature and high conductivity based on density functional theory (DFT) calculational and experimental comparison for different R groups in RCONH2 and different lithium salts. PMID:15911385

Hu, Yongsheng; Wang, Zhaoxiang; Li, Hong; Huang, Xuejie; Chen, Liquan



Polarizable force field development and molecular dynamics simulations of ionic liquids.  


A many-body polarizable force field has been developed and validated for ionic liquids (ILs) containing 1-methyl-3-alkylimidazolium, 1-alkyl-2-methyl-3-alkylimidazolium, N-methyl-N-alkylpyrrolidinium, N-alkylpyridinium, N-alkyl-N-alkylpiperidinium, N-alkyl-N-alkylmorpholinium, tetraalkylammonium, tetraalkylphosphonium, N-methyl-N-oligoetherpyrrolidinium cations and BF(4)(-), CF(3)BF(3)(-), CH(3)BF(3)(-), CF(3)SO(3)(-), PF(6)(-), dicyanamide, tricyanomethanide, tetracyanoborate, bis(trifluoromethane sulfonyl)imide (Ntf(2)(-) or TFSI(-)), bis(fluorosulfonyl)imide (FSI(-)) and nitrate anions. Classical molecular dynamics (MD) simulations have been performed on 30 ionic liquids at 298, 333, and 393 K. The IL density, heat of vaporization, ion self-diffusion coefficient, conductivity, and viscosity were found in a good agreement with available experimental data. Ability of the developed force field to predict ionic crystal cell parameters has been tested on four ionic crystals containing Ntf(2)(-) anions. The influence of polarization on the structure and ion transport has been investigated for [emim][BF(4)] IL. A connection between the structural changes in IL resulting from turning off polarization and slowing down of ion dynamics has been found. Developed force field has also provided accurate description/prediction of thermodynamic and transport properties of alkanes, fluoroalkanes, oligoethers (1,2-dimethoxyethane), ethylene carbonate, propylene carbonate, dimethyl carbonate, hydrazine, methyhydrazine, dimethylhydrazine, acetonitrile, dimethyl amine, and dimethyl ketone. PMID:19637900

Borodin, Oleg



Gas Permeation through Polystyrene-Poly(ethylene oxide) Block Copolymers  

NASA Astrophysics Data System (ADS)

Lithium air batteries are a potential technology for affordable energy storage. They consist of a lithium metal anode and a porous air cathode separated by a solid polymer electrolyte membrane, such as PEO/LiTFSI (PEO = poly(ethylene oxide), LiTFSI = lithium bis-trifluoromethane sulfonimide). For extended operation of such a battery, the polymer electrolyte must conduct lithium ions while blocking electrons and gases present in air. In order to maintain a pressure difference the membrane must be mechanically robust, which can be achieved by incorporating the PEO into a block copolymer with a glassy block such as PS (PS = polystyrene). To protect the lithium electrode, the membrane must have low permeability to gases in air such as CO2, N2, and O2. We have therefore studied the permeation of pure gases through a PS-PEO block copolymer. A high molecular weight, symmetric block copolymer with a lamellar morphology was used to cast free-standing membranes. Gas permeability was measured through these membranes with a standard, pressure-based technique. A model was developed to account for transport through the polymer membrane consisting of semi-crystalline PEO lamellae and amorphous PS lamellae. PEO crystallinity was extracted from the permeation model and compares well with values from differential scanning calorimetry measurements.

Hallinan, Daniel, Jr.; Minelli, Matteo; Giacinti-Baschetti, Marco; Balsara, Nitash



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

SciTech Connect

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

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



The effect of coordinating and non-coordinating additives on the transport properties in ionic liquid electrolytes for lithium batteries.  


In the present study we expand our analysis of using two contrasting organic solvent additives (toluene and THF) in an ionic liquid (IL)/Li NTf(2) electrolyte. Multinuclear Pulsed-Field Gradient (PFG) NMR, spin-lattice (T(1)) relaxation times and conductivity measurements over a wide temperature range are discussed in terms of transport properties and structuring of the liquid. The conductivity of both additive samples is enhanced the most at low temperatures, with THF slightly more effective than toluene. Both the anion and lithium self-diffusivity are enhanced in the same order by the additives (THF > toluene) while that of the pyrrolidinium cation is marginally enhanced. (1)H spin-lattice relaxation times indicate a reasonable degree of structuring and anisotropic motion within all of the samples and both (19)F and (7)Li highlight the effectiveness of THF at influencing the lithium coordination within these systems. PMID:21279209

Bayley, Paul M; Best, A S; MacFarlane, D R; Forsyth, M



Melting-Point Estimation of Ionic Liquids by a Group Contribution Method  

NASA Astrophysics Data System (ADS)

Based on experimental data collected from the literature, a group contribution method for estimating the melting points of imidazolium-, pyridinium-, pyrrolidinium-, ammonium-, phosphonium-, and piperidinium-based ionic liquids (ILs) with common anions is proposed. The method considers the contributions of ionic groups and methylene groups, as additive parameters, and two nonadditive characteristic geometric parameters of cations such as symmetry and flexibility. A total of 293 data points for 136 ILs were used in this study. The average relative deviation and the average absolute deviation of the proposed model are 7.8% and 22.6 K, respectively. It is concluded that the proposal is useful for the prediction of the melting points for a wide range of ILs.

Aguirre, Claudia L.; Cisternas, Luis A.; Valderrama, José O.



Benzene solubility in ionic liquids: working toward an understanding of liquid clathrate formation.  


The solubility of benzene in 15 imidazolium, pyrrolidinium, pyridinium, and piperidinium ionic liquids has been determined; the resulting, benzene-saturated ionic liquid solutions, also known as liquid clathrates, were examined with (1) H and (19) F nuclear magnetic resonance spectroscopy to try and understand the molecular interactions that control liquid clathrate formation. The results suggest that benzene interacts primarily with the cation of the ionic liquid, and that liquid clathrate formation (and benzene solubility) is controlled by the strength of the cation-anion interactions, that is, the stronger the cation-anion interaction, the lower the benzene solubility. Other factors that were determined to be important in the final amount of benzene in any given liquid clathrate phase included attractive interactions between the anion and benzene (when significant), and larger steric or free volume demands of the ions, both of which lead to greater benzene solubility. PMID:25297708

Pereira, Jorge F B; Flores, Luis A; Wang, Hui; Rogers, Robin D



Mixtures of protic ionic liquids and propylene carbonate as advanced electrolytes for lithium-ion batteries.  


In this study we investigated the chemical-physical properties of mixtures containing the protic ionic liquid (PIL) N-butyl-pyrrolidinium bis(trifluoromethanesulfonyl)imide (PYRH4TFSI), propylene carbonate (PC) and lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) in view of their use as electrolytes for lithium-ion batteries (LIBs). We showed that these electrolytic solutions might display conductivity and viscosity comparable to those of conventional electrolytes. Depending on the amount of PIL present inside the mixtures, such mixtures might also display the ability to suppress the anodic dissolution of Al. Furthermore, we showed that the coordination of lithium ions by TFSI in PIL-PC mixtures appears to be different than the one observed for mixtures of PC and aprotic ionic liquids (AILs). When used in combination with a battery electrode, e.g. lithium iron phosphate (LFP), these mixtures allow the achievement of high performance also at a very high C-rate. PMID:25328075

Vogl, T; Menne, S; Balducci, A



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


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

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



Factors stabilizing the gas-phase ionic species of crystals of organic salts - Experimental and theoretical study  

NASA Astrophysics Data System (ADS)

The paper studied factors of the gas phase (GP) ionic stabilization of molecular organic crystals of salts. The single crystal X-ray diffraction, electrospray ionization (ESI) and matrix-assisted laser desorption/ionization (MALDI) mass spectrometric (MS) methods are employed. The GP phenomena are explained by the comprehensive quantum-chemical theoretical models, providing significant information for the electronic structures and thermodynamics of the observed MS species. The n-chloro-alkyl aliphatic heterocyclic 5-sulfosalicylates i.e. 1-(2-chloroethyl) pyrrolidinium 5-sulfosalicylicilate (1), 1-(2-chloroethyl)-piperidinium 5-sulfosalicylicilate (2), and 1-(3-chloropropyl) piperidinium 5-sulfosalicylicilate (3) are examined. The ionic systems that contain N+H-heterocyclic fragments, a complex MS image variety of monocations, quaternary ammonium dications and hydrogen bonded molecular complexes revealed. Their stabilization is explained by proton transfer (PT), charge-transfer (CT) and Jahn-Teller (JT) effects. The 4-(2-chloroethyl) morpholinium hydrochloride crystals (4) yielded quaternary ammonium adduct which structure is crystallographically determined. In parallel the GP stabilized ions of 4 are analyzed. The complementary application of the single-crystal X-ray diffraction and MS methods provided unique structural evidences in condenses and in the GP able to understand the competitive intramolecular and environmental factors contributing to the thermodynamics stability of the ionic species. Therefore, the data reported are helped for more comprehensive knowledge of the basic mass spectrometric GP and phase transition phenomena with both its methodological development and used robust analytical technique application.

Ivanova, Bojidarka B.; Spiteller, Michael



Extraction Separation of Rare-Earth Ions via Competitive Ligand Complexations between Aqueous and Ionic-Liquid Phases  

SciTech Connect

The extraction separation of rare earth elements is the most challenging separation processes in hydrometallurgy and advanced nuclear fuel cycles. The TALSPEAK process (Trivalent Actinide Lanthanide Separations by Phosphorus-reagent Extraction from Aqueous Komplexes) is a prime example of these separation processes. The objective of this paper is to explore the use of ionic liquids (ILs) for the TALSPEAK-like process, to further enhance its extraction efficiencies for lanthanides, and to investigate the potential of using this modified TALSPEAK process for separation of lanthanides among themselves. Eight imidazolium ILs ([Cnmim][NTf2] and [Cnmim][BETI], n=4,6,8,10) and one pyrrolidinium IL ([C4mPy][NTf2]) were investigated as diluents using di(2-ethylhexyl)phosphoric acid (HDEHP) as an extractant for separation of lanthanide ions from aqueous solutions of 50 mM glycolic acid or citric acid and 5 mM diethylenetriamine pentaacetic acid (DTPA). The extraction efficiencies were studied in comparison with diisopropylbenzene (DIPB), an organic solvent used as diluent for the conventional TALSPEAK extraction system. Excellent extraction efficiencies and selectivities were found for a number of lanthanide ions using HDEHP as an extractant in these ILs. The effects of different alkyl chain lengths in the cations of ILs and anions on extraction efficiencies and selectivities of lanthanide ions are also presented in this paper.

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



Characteristics of aggregation in aqueous solutions of dialkylpyrrolidinium bromides.  


Three pyrrolidinium-based ionic liquids-N-dodecyl-N-methylpyrrolidinium bromide, N-butyl-N-octylpyrrolidinium bromide, and N-butyl-N-dodecylpyrrolodinium bromide-were synthesized and characterized by their decomposition temperatures (T(d)) measured by thermogravimetric analysis, and by their melting point (T(m)), glass transition (T(g)) and crystallization temperatures (T(cryst)) determined by differential scanning calorimetry. Their self-aggregation properties in aqueous solution were studied and their behavior is compared with that of analogous conventional cationic surfactants, namely tetra-alkylammonium bromide salts. The critical micellar concentration, cmcs were obtained by isothermal titration calorimetry (ITC); which were further validated by measurements of interfacial tension, fluorescence and NMR spectroscopy. Enthalpies of micellization were measured at three different temperatures using ITC. The Taylor dispersion method and DOSY NMR were used to determine diffusion coefficients of the ionic liquid surfactants in aqueous solution at 298.15K. Several correlations between structural features of the surfactant species, such as the number and size of their alkyl chains, and the thermodynamic quantities of micellization-expressed by experimental values of cmc, counter-ion binding fraction, ?(mic)G°, ?(mic)°, and ?(mic)S°-are established. We could interpret the different contributions of the two alkyl side chains to the aggregation properties in terms of the balance of interactions in homogeneous and micellar phases, contributing to understanding the aggregation behavior of ionic liquids in water and the parallel between these systems and traditional ionic surfactants. PMID:21601215

Tariq, M; Podgoršek, A; Ferguson, J L; Lopes, A; Costa Gomes, M F; Pádua, A A H; Rebelo, L P N; Canongia Lopes, J N



Ionic liquids for rechargeable lithium batteries  

SciTech Connect

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

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



Methane-oxygen electrochemical coupling in an ionic liquid: a robust sensor for simultaneous quantification.  


Current sensor devices for the detection of methane or natural gas emission are either expensive and have high power requirements or fail to provide a rapid response. This report describes an electrochemical methane sensor utilizing a non-volatile and conductive pyrrolidinium-based ionic liquid (IL) electrolyte and an innovative internal standard method for methane and oxygen dual-gas detection with high sensitivity, selectivity, and stability. At a platinum electrode in bis(trifluoromethylsulfonyl)imide (NTf2)-based ILs, methane is electro-oxidized to produce CO2 and water when an oxygen reduction process is included. The in situ generated CO2 arising from methane oxidation was shown to provide an excellent internal standard for quantification of the electrochemical oxygen sensor signal. The simultaneous quantification of both methane and oxygen in real time strengthens the reliability of the measurements by cross-validation of two ambient gases occurring within a single sample matrix and allows for the elimination of several types of random and systematic errors in the detection. We have also validated this IL-based methane sensor employing both conventional solid macroelectrodes and flexible microfabricated electrodes using single- and double-potential step chronoamperometry. PMID:25093213

Wang, Zhe; Guo, Min; Baker, Gary A; Stetter, Joseph R; Lin, Lu; Mason, Andrew J; Zeng, Xiangqun



Nonaborane and decaborane cluster anions can enhance the ignition delay in hypergolic ionic liquids and induce hypergolicity in molecular solvents.  


The dissolution of nido-decaborane, B10H14, in ionic liquids that are hypergolic (fuels that spontaneously ignite upon contact with an appropriate oxidizer), 1-butyl-3-methylimidazolium dicyanamide, 1-methyl-4-amino-1,2,4-triazolium dicyanamide, and 1-allyl-3-methylimidazolium dicyanamide, led to the in situ generation of a nonaborane cluster anion, [B9H14](-), and reductions in ignition delays for the ionic liquids suggesting salts of borane anions could enhance hypergolic properties of ionic liquids. To explore these results, four salts based on [B10H13](-) and [B9H14](-), triethylammonium nido-decaborane, tetraethylammonium nido-decaborane, 1-ethyl-3-methylimidazolium arachno-nonaborane, and N-butyl-N-methyl-pyrrolidinium arachano-nonaborane were synthesized from nido-decaborane by reaction of triethylamine or tetraethylammonium hydroxide with nido-decaborane in the case of salts containing the decaborane anion or via metathesis reactions between sodium nonaborane (Na[B9H14]) and the corresponding organic chloride in the case of the salts containing the nonaborane anion. These borane cluster anion salts form stable solutions in some combustible polar aprotic solvents such as tetrahydrofuran and ethyl acetate and trigger hypergolic reactivity of these solutions. Solutions of these salts in polar protic solvents are not hypergolic. PMID:24716643

McCrary, Parker D; Barber, Patrick S; Kelley, Steven P; Rogers, Robin D



Ionic liquid mixtures--an analysis of their mutual miscibility.  


The use of ionic liquid mixtures (IL-IL mixtures) is being investigated for fine solvent properties tuning of the IL-based systems. The scarce available studies, however, evidence a wide variety of mixing behaviors (from almost ideal to strongly nonideal), depending on both the structure of the IL components and the property considered. In fact, the adequate selection of the cations and anions involved in IL-IL mixtures may ensure the absence or presence of two immiscible liquid phases. In this work, a systematic computational study of the mixing behavior of IL-IL systems is developed by means of COSMO-RS methodology. Liquid-liquid equilibrium (LLE) and excess enthalpy (H(E)) data of more than 200 binary IL-IL mixtures (including imidazolium-, pyridinium-, pyrrolidinium-, ammonium-, and phosphonium-based ILs) are calculated at different temperatures, comparing to literature data when available. The role of the interactions between unlike cations and anions on the mutual miscibility/immiscibility of IL-IL mixtures was analyzed. On the basis of proposed guidelines, a new class of immiscible IL-IL mixtures was reported, which only is formed by imidazolium-based compounds. PMID:24521179

Omar, Salama; Lemus, Jesus; Ruiz, Elia; Ferro, Víctor R; Ortega, Juan; Palomar, Jose



Composition and structural effects on the adsorption of ionic liquids onto activated carbon.  


The applications and variety of ionic liquids (ILs) have increased during the last few years, and their use at a large scale will require their removal/recovery from wastewater streams. Adsorption on activated carbons (ACs) has been recently proposed for this aim and this work presents a systematic analysis of the influence of the IL chemical structures (cation side chain, head group, anion type and the presence of functional groups) on their adsorption onto commercial AC from water solution. Here, the adsorption of 21 new ILs, which include imidazolium-, pyridinium-, pyrrolidinium-, piperidinium-, phosphonium- and ammonium-based cations and different hydrophobic and hydrophilic anions, has been experimentally measured. This contribution allows an expansion of the range of IL compounds studied in previous works, and permits a better understanding of the influence of the IL structures through the adsorption on AC. In addition, the COSMO-RS method was used to analyze the measured adsorption isotherms, allowing the understanding of the role of the cationic and anionic structures in the adsorption process, in terms of the different interactions between the IL compound and AC surface/water solvent. The results of this work provide new insights for the development of adsorption as an effective operation to remove/recover ILs with very different chemical nature from water solution. PMID:23896624

Lemus, Jesús; Neves, Catarina M S S; Marques, Carlos F C; Freire, Mara G; Coutinho, João A P; Palomar, Jose



Effect of cationic head group on micellization behavior of new amide-functionalized surface active ionic liquids.  


Amide-functionalized surface active ionic liquids (SAILs), 1-methyl-1-dodecyl piperidinium chloride, [C12APip][Cl]; 1-methyl-1-dodecyl pyrrolidinium chloride, [C12APyrr][Cl]; 1-methyl-3-dodecyl imidazolium chloride, [C12Amim][Cl], and 1-methyl-1-dodecyl morpholinium chloride, [C12AMorph][Cl], have been synthesized, characterized and investigated for thermal stability, and micellization behavior in aqueous medium. The introduction of an amide moiety in the alkyl chain decreased the thermal stability of the functionalized SAILs compared to non-functionalized SAILs bearing a simple alkyl chain. A variety of state of the art techniques, viz. tensiometry, conductometry, steady-state fluorescence, isothermal titration calorimetry (ITC), dynamic light scattering (DLS) and atomic force microscopy (AFM), have been employed to investigate the micellization behavior. Amide-functionalized SAILs have shown much lower critical micelle concentration, cmc, and better surface active properties as compared to homologous non-functionalized SAILs. Steady-state fluorescence has provided information about cmc, aggregation number (Nagg) and polarity of the cybotactic region of the micelles, whereas ITC has provided insights into the thermodynamics of micellization. Furthermore, the size and shape of the micelles have been investigated using DLS and AFM techniques. PMID:25361232

Kamboj, Raman; Bharmoria, Pankaj; Chauhan, Vinay; Singh, Gurbir; Kumar, Arvind; Singh, Sukhprit; Kang, Tejwant Singh



LDI and ESI MS as well as low energy CID of a self-assembling nanorod-forming fullerene derivative.  


An amphiphatic fullerene derivative (8-(N-Methyl-Fullero-Pyrrolidinium-1-yl-chloride)-3,6-Dioxaoctan-1-Ammonium Chloride (MFPDAC)), which is of great interest in nanotechnology due to the fact that it forms self-assembling fullerenic nanorods, has been structurally characterized with emphasis to its purity and thermal treatment of a formed nanorod film (on a LDI target) by means of laser desorption/ionization (LDI) coupled with high-resolution curved field reflectron time-of-flight (TOF) mass spectrometry, and by low energy MS/MS as well as in-source fragmentation experiments applying an quadrupole ion trap (QIT) combined with a two-stage reflectron TOF analyzer. The interpretation of LDI results has been supplemented by ESI QIT MS(n) (n = 1-3), as well as high-resolution ESI reflectron TOF mass spectrometric experiments. Based on the experimental data obtained by both desorption/ionization techniques, various types of analyzers and sample treatments, we could completely characterize MFPDAC and further found out that the investigated sample was not entirely free of impurities. Furthermore, the envisaged loss of the derivative sidechain upon the heat treatment in vacuum of the self-assembled nanorod sample film on a metallic substrate could be successfully monitored by LDI MS. PMID:22124981

Rechthaler, Justyna; Pelzing, Matthias; Ingendoh, Arndt; Kukovecz, Akos; Prato, Maurizio; Kuzmany, Hans; Allmaier, Günter



Electrochemical reduction of O2 in 1-butyl-1-methylpyrrolidinium bis(trifluoromethanesulfonyl)imide ionic liquid containing Zn2+ cations: deposition of non-polar oriented ZnO nanocrystalline films.  


The influence of the Zn(2+) concentration and temperature on the electrochemical reduction of O(2) in a solution of zinc bis(trifluoromethanesulfonyl)imide (Zn(TFSI)(2)) salt in 1-butyl-1-methylpyrrolidinium bis(trifluoromethanesulfonyl)imide (PYR(14)TFSI) ionic liquid is presented. ZnO nanocrystalline films were then electrodeposited, under enhanced O(2) reduction, at temperatures in the 75-150 °C range. Their morphology, chemical composition, structural and optical properties were analyzed. In contrast to the polar-oriented ZnO usually obtained from aqueous and conventional solvent based electrolytes, nanocrystalline films oriented along non-polar directions, (11 ?10) and (11 ?20), were obtained from this ionic liquid electrolyte. A significant content of carbon was detected in the films, pointing to the active participation and crucial effect of pyrrolidinium cation (and/or byproducts) during the electrodeposition. The films showed semiconducting behavior with an optical gap between 3.43 and 3.53 eV as measured by optical transmittance. Their room temperature photoluminescence spectra exhibited two different bands centered at ?3.4 and ?2.2 eV. The intensity ratio between both bands was found to depend on the deposition temperature. This work demonstrates the great potential of ionic liquids based electrolytes for the electrodeposition of ZnO nanocrystalline thin films with innovative microstructural and optoelectronic properties. PMID:21709895

Azaceta, Eneko; Marcilla, Rebeca; Mecerreyes, David; Ungureanu, Mariana; Dev, Apurba; Voss, Tobias; Fantini, Sebastian; Grande, Hans-Jurgen; Cabañero, German; Tena-Zaera, Ramon



One-step hydrothermal synthesis of mesoporous anatase TiO? microsphere and interfacial control for enhanced lithium storage performance.  


Mesoporous TiO(2) anatase microspheres consisting of self-assembled nanocrystals have been synthesized by a one-step hydrothermal method at 120 (o)C using titanium-peroxo complex, without a post-calcination process. Transmission and scanning electron microscopic imaging reveal that diamond-shaped nanocrystals as primary particles, which are 20 nm in average width and 50 nm in length and oriented with (101) plane of anatase phase, are aggregated to form a secondary microsphere particle with 0.5-1 ?m in diameter. BET analysis data show that the TiO(2) anatase particles possess significantly large surface area of 254 m(2) g(-1) with the pore size of ?14 nm. Mesoporous TiO(2) anatase anode shows an enhanced lithium storage performance in pyrrolidinium-based ionic liquid electrolyte diluted with ethyl methyl carbonate, delivering 195 - 150 mAhg(-1) at the C/2 rate with 77 % capacity retention and 98-99 % Coulombic efficiencies over 50 cycles despite the absence of surface carbon-coating. AC impedance analysis results reveal that the formation of a stable solid electrolyte interphase (SEI) layer in diluted ionic liquid electrolyte induces the enhanced cycling performance. Control of electrode-electrolyte interfacial compatibility enables the enhancement of cycling performance and the preservation of microstructure. The data contribute to provide cost-efficient synthetic method for the TiO(2) and the interfacial control aspect of performance control for safer batteries. PMID:21848346

Lee, Kyung-Ho; Song, Seung-Wan



Cationic gemini surfactants as pseudostationary phases in micellar electrokinetic chromatography. Part I: effect of head group.  


Two cationic gemini surfactants with pyrrolidinium or alkyl ammonium head groups with but-2-yne spacers, but with the same length hydrocarbon chain have been characterized with respect to their aggregation behaviors and separation power as pseudostationary phases (PSPs) for micellar electrokinetic chromatography (MEKC). They were compared with a commonly used PSP, sodium dodecylsulfate (SDS). The results suggest that the head groups of the surfactants have some effect on physicochemical properties such as critical micelle concentration (CMC), C(20), gamma(CMC), partial specific volume, methylene selectivity and mobilities of the surfactants. CMC values of G1, G2 and SDS in pure water were found to be 0.82, 0.71, and 8.08 mM, respectively; they were reduced to 0.21, 0.11, and 3.0 mM when measured in 10 mM phosphate buffer at pH 7.0. G1 (alphaCH2 = 2.74) and G2 (alphaCH2 = 2.48) provided the most and the least hydrophobic environment, respectively. According to their partial specific volumes, geminis were found to have more flexible structures as compared with sodium dodecylsulfate. The effects of the head group structure were also characterized with the linear solvation energy relationship (LSER) model, which was able to evaluate the role of solute size, polarity/polarizability, and hydrogen bonding on retention and selectivity. The cohesiveness, hydrogen bond acidic and basic character of the surfactant systems were found to have the most significant influence on selectivity and MEKC retention of the gemini surfactants. It should be noted that with their large positive coefficient a values, G1 and G2 were found to be stronger HB acceptors than anionic and most of the cationic surfactants studied in the literature. PMID:20598697

Akbay, Cevdet; Hoyos, Yatzka; Hooper, Edward; Arslan, Hakan; Rizvi, Syed A A



Electrodeposition of Al in 1-butyl-1-methylpyrrolidinium bis(trifluoromethylsulfonyl)amide and 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)amide ionic liquids: in situ STM and EQCM studies.  


In the present paper, the electrodeposition of Al on flame-annealed Au(111) and polycrystalline Au substrates in two air- and water-stable ionic liquids namely, 1-butyl-1-methyl-pyrrolidinium bis(trifluoromethylsulfonyl)amide, [Py(1,4)]Tf(2)N, and 1-ethyl-3-methyl-imidazolium bis(trifluoromethylsulfonyl)amide, [EMIm]Tf(2)N, has been investigated by in situ scanning tunneling microscopy (STM), electrochemical quartz crystal microbalance (EQCM), and cyclic voltammetry. The cyclic voltammogram of aluminum deposition and stripping on Au(111) in the upper phase of the biphasic mixture of AlCl(3)/[EMIm]Tf(2)N at room temperature (25 degrees C) shows that the electrodeposition process is completely reversible as also evidenced by in situ STM and EQCM studies. Additionally, a cathodic peak at an electrode potential of about 0.55 V vs Al/Al(III) is correlated to the aluminum UPD process that was evidenced by in situ STM. A surface alloying of Al with Au at the early stage of deposition occurs. It has been found that the Au(111) surface is subject to a restructuring/reconstruction in the upper phase of the biphasic mixture of AlCl(3)/[Py(1,4)]Tf(2)N at room temperature (25 degrees C) and that the deposition is not fully reversible. Furthermore, the underpotential deposition of Al in [Py(1,4)]Tf(2)N is not as clear as in [EMIm]Tf(2)N. The frequency shift in the EQCM experiments in [Py(1,4)]Tf(2)N shows a surprising result as an increase in frequency and a decrease in damping with bulk aluminum deposition at potentials more negative than -1.8 V was observed at room temperature. However, at 100 degrees C there is a frequency decrease with ongoing Al deposition. At -2.0 V vs Al/Al(III), a bulk aluminum deposition sets in. PMID:17388503

Moustafa, E M; El Abedin, S Zein; Shkurankov, A; Zschippang, E; Saad, A Y; Bund, A; Endres, F



CNT loading into cationic cholesterol suspensions show improved DNA binding and serum stability and ability to internalize into cancer cells  

NASA Astrophysics Data System (ADS)

Methods which disperse single-walled carbon nanotubes (SWNTs) in water as ‘debundled’, while maintaining their unique physical properties are highly useful. We present here a family of cationic cholesterol compounds (Chol+) {Cholest-5en-3?-oxyethyl pyridinium bromide (Chol-PB+), Cholest-5en-3?-oxyethyl N-methyl pyrrolidinium bromide (Chol-MPB+), Cholest-5en-3?-oxyethyl N-methyl morpholinium bromide (Chol-MMB+) and Cholest-5en-3?-oxyethyl diazabicyclo octanium bromide (Chol-DOB+)}. Each of these could be easily dispersed in water. The resulting cationic cholesterol (Chol+) suspensions solubilized single-walled carbon nanotubes (SWCNTs) by the non-specific physical adsorption of Chol+ to form stable, transparent, dark aqueous suspensions at room temperature. Electron microscopy reveals the existence of highly segregated CNTs in these samples. Zeta potential measurements showed an increase in potential of cationic cholesterol aggregates on addition of CNTs. The CNT-Chol+ suspensions were capable of forming stable complexes with genes (DNA) efficiently. The release of double-helical DNA from such CNT-Chol+ complexes could be induced upon the addition of anionic micellar solution of SDS. Furthermore, the CNT-based DNA complexes containing cationic cholesterol aggregates showed higher stability in fetal bovine serum media at physiological conditions. Confocal studies confirm that CNT-Chol+ formulations adhere to HeLa cell surfaces and get internalized more efficiently than the cationic cholesterol suspensions alone (devoid of any CNTs). These cationic cholesterol-CNT suspensions therefore appear to be a promising system for further use in biological applications.

Chhikara, Bhupender S.; Misra, Santosh K.; Bhattacharya, Santanu



Facile synthesis of carbon-11-labeled cholesterol-based cationic lipids as new potential PET probes for imaging of gene delivery in cancer.  


Gene therapy based on gene delivery is a promising strategy for the treatment of various human diseases such as cancer. Cationic lipids represent one of the important synthetic gene delivery systems. There is a great interest in imaging of gene therapy using the biomedical imaging technique positron emission tomography (PET). Carbon-11-labeled cholesterol-based cationic lipids were first designed and synthesized as new potential PET probes for imaging of gene delivery in cancer. The [(11)C-methyl]quaternary amine target tracers, N-[(11)C]methyl-N-[4-(cholest-5-en-3beta-yloxycarbonyl)butyl]pyrrolidinium iodide ([(11)C]4a), N-[(11)C]methyl-N'-[4-(cholest-5-en-3beta-yloxycarbonyl)butyl]imidazolium iodide ([(11)C]4b), N-[(11)C]methyl-N-[4-(cholest-5-en-3beta-yloxycarbonyl)butyl]piperidinium iodide ([(11)C]4c), N-[(11)C]methyl-N-[4-(cholest-5-en-3beta-yloxycarbonyl)butyl]-4-methylpiperidinium iodide ([(11)C]4d), and N-[(11)C]methyl-N-[4-(cholest-5-en-3beta-yloxycarbonyl)butyl]morpholinium iodide ([(11)C]4e), were prepared from their corresponding tertiary amine precursors with [(11)C]methyl iodide ([(11)C]CH(3)I) through N-[(11)C]methylation and isolated by a simplified solid-phase extraction (SPE) method using a Silica Sep-Pak cartridge in 50-60% radiochemical yields decay corrected to end-of-bombardment (EOB), based on [(11)C]CO(2), and 111-185GBq/mumol specific activity at the end of synthesis (EOS). PMID:20451540

Gao, Mingzhang; Wang, Min; Miller, Kathy D; Sledge, George W; Hutchins, Gary D; Zheng, Qi-Huang



Li+ cation environment, transport, and mechanical properties of the LiTFSI doped N-methyl-N-alkylpyrrolidinium+TFSI- ionic liquids.  


Molecular dynamics (MD) simulations have been performed on N-methyl-N-propylpyrrolidinium bis(trifluoromethanesulfonyl)imide (mppy(+)TFSI(-)) and N,N-dimethyl- pyrrolidinium bis(trifluoromethanesulfonyl)imide (mmpy(+)TFSI(+)) ionic liquids (ILs) doped with 0.25 mol fraction LiTFSI salt at 303-500 K. The liquid density, ion self-diffusion coefficients, and conductivity predicted by MD simulations were found to be in good agreement with experimental data, where available. MD simulations reveal that the Li(+) environment is similar in mppy(+)TFSI(-) and mmpy(+)TFSI(+) ILs doped with LiTFSI. The Li(+) cations were found to be coordinated on average by slightly less than four oxygen atoms with each oxygen atom being contributed by a different TFSI(-) anion. Significant lithium aggregation by sharing up to three TFSI(-) anions bridging two lithiums was observed, particularly at lower temperatures where the lithium aggregates were found to be stable for tens of nanoseconds. Polarization of TFSI(-) anions is largely responsible for the formation of such lithium aggregates. Li(+) transport was found to occur primarily by exchange of TFSI(-) anions in the first coordination shell with a smaller (approximately 30%) contribution also due to Li(+) cations diffusing together with their first coordination shell. In both ILs, ion self-diffusion coefficients followed the order Li(+) < TFSI(-) < mmpy(+) or mppy(+) with all ion diffusion in mmpy(+)TFSI(-) being systematically slower than that in mppy(+)TFSI(-). Conductivity due to the Li(+) cation in LiTFSI doped mppy(+)TFSI(-) IL was found to be greater than that for a model poly(ethylene oxide)(PEO)/LiTFSI polymer electrolyte but significantly lower than that for an ethylene carbonate/LiTFSI liquid electrolyte. Finally, the time-dependent shear modulus for the LiTFSI doped ILs was found to be similar to that for a model poly(ethylene oxide)(PEO)/LiTFSI polymer electrolyte on the subnanosecond time scale. PMID:16927976

Borodin, Oleg; Smith, Grant D; Henderson, Wesley



Functionalized fullerenes mediate photodynamic killing of cancer cells: Type I versus Type II photochemical mechanism  

PubMed Central

Photodynamic therapy (PDT) employs the combination of non-toxic photosensitizers (PS) and harmless visible light to generate reactive oxygen species (ROS) and kill cells. Most clinically studied PS are based on the tetrapyrrole structure of porphyrins, chlorins and related molecules, but new non-tetrapyrrole PS are being sought. Fullerenes are soccer-ball shaped molecules composed of sixty or seventy carbon atoms and have attracted interest in connection with the search for biomedical applications of nanotechnology. Fullerenes are biologically inert unless derivatized with functional groups, whereupon they become soluble and can act as PS. We have compared the photodynamic activity of six functionalized fullerenes with 1, 2, or 3 hydrophilic or 1, 2, or 3 cationic groups. The octanol-water partition coefficients were determined and the relative contributions of Type I photochemistry (photogeneration of superoxide in the presence of NADH) and Type II photochemistry (photogeneration of singlet oxygen) were studied by measurement of oxygen consumption, 1270-nm luminescence and EPR spin-trapping of the superoxide product. We studied three mouse cancer cell lines: (J774, LLC and CT26) incubated for 24 h with fullerenes and illuminated with white light. The order of effectiveness as PS was inversely proportional to the degree of substitution of the fullerene nucleus for both the neutral and cationic series. The mono-pyrrolidinium fullerene was the most active PS against all cell lines and induced apoptosis 4–6 hours after illumination. It produced diffuse intracellular fluorescence when dichlorodihydrofluorescein was added as an ROS probe suggesting a Type I mechanism for phototoxicity. We conclude that certain functionalized fullerenes have potential as novel PDT agents and phototoxicity may be mediated both by superoxide and by singlet oxygen. PMID:17664135

Mroz, Pawel; Pawlak, Anna; Satti, Minahil; Lee, Haeryeon; Wharton, Tim; Gali, Hariprasad; Sarna, Tadeusz; Hamblin, Michael R.



The effect of the cation alkyl chain branching on mutual solubilities with water and toxicities.  


The design of ionic liquids has been focused on the cation-anion combinations but other more subtle approaches can be used. In this work the effect of the branching of the cation alkyl chain on the design of ionic liquids (ILs) is evaluated. The mutual solubilities with water and toxicities of a series of bis(trifluoromethylsulfonyl)-based ILs, combined with imidazolium, pyridinium, pyrrolidinium, and piperidinium cations with linear or branched alkyl chains, are reported. The mutual solubility measurements were carried out in the temperature range from (288.15 to 323.15) K. From the obtained experimental data, the thermodynamic properties of the solution (in the water-rich phase) were determined and discussed. The COnductor like Screening MOdel for Real Solvents (COSMO-RS) was used to predict the liquid-liquid equilibrium. Furthermore, molecular dynamic simulations were also carried out aiming to get a deeper understanding of these fluids at the molecular level. The results show that the increase in the number of atoms at the cation ring (from five to six) leads to a decrease in the mutual solubilities with water while increasing their toxicity, and as expected from the well-established relationship between toxicities and hydrophobicities of ILs. The branching of the alkyl chain was observed to decrease the water solubility in ILs, while increasing the ILs solubility in water. The inability of COSMO-RS to correctly predict the effect of branching alkyl chains toward water solubility on them was confirmed using molecular dynamic simulations to be due to the formation of nano-segregated structures of the ILs that are not taken into account by the COSMO-RS model. In addition, the impact of branched alkyl chains on the toxicity is shown to be not trivial and to depend on the aromatic nature of the ILs. PMID:25119425

Kurnia, Kiki A; Sintra, Tânia E; Neves, Catarina M S S; Shimizu, Karina; Canongia Lopes, José N; Gonçalves, Fernando; Ventura, Sónia P M; Freire, Mara G; Santos, Luís M N B F; Coutinho, João A P



Symposium Report. Battery materials : amorphous carbons and polymer electrolytes.  

SciTech Connect

The motivation for research in battery materials lies in the expanding consumer demand for compact, high-energy density power sources for portable electronic devices, and environmental issues such as global warming and air pollution that have provided the impetus for mass transportation by electric vehicles. The Battery Materials Symposium, chaired by Jacqueline Johnson (ANL), focused on three topics: the structure and electrochemical properties of new and existing electrolytes, devices for fabricating and investigating thin films, and large-scale computer simulations. The symposium opened with a presentation by the author on a recently invented device for in situ investigations of batteries using nuclear magnetic resonance. Joop Schoonman (Delft University) described several methods for preparing and analyzing thin films made of solid electrolytes. These methods included chemical vapor deposition, electrostatic spray deposition and the Solufill process. Aiichiro Nakano discussed large-scale (10 million to 2 billion atoms) computer simulations of polymer and ceramic systems. An overview was given of a DOE Cooperative Research 2000 program, in the initial stages, that was set up to pursue these atomistic simulations. Doug MacFarlane (Monash University) described conductive plastic crystals based on pyrrolidinium imides. Joseph Pluth (U of Chicago) presented his recent crystallographic studies of Pb compounds found in the ubiquitous lead-acid battery. He showed the structures of tribasic lead sulfate and tetrabasic lead sulfate. Austen Angell (Arizona State Univ.) discussed the general problem of electrolyte polarization in Li-ion battery systems with cation transference numbers less than unity. Steven Greenbaum (Hunter College) provided an introduction of NMR interactions that are useful for investigations of lithium-ion battery materials. Analysis by NMR is nuclear specific, probes local environments and dynamics, and is non-destructive. He discussed {sup 7}Li NMR results of a solid electrolyte system composed of LiI dissolved in PEO. Work on oriented polymer electrolyte samples is ongoing. Yuri Andreev (U. of St. Andrews) gave a historical overview of a number of crystal structures of polymer electrolytes solved using XRD in the group of Peter Bruce. The last speaker of the symposium was Peter Papanek (U. of Pennsylvania). He spoke about various disordered carbon materials used as anodes in Li-ion batteries. He also described his inelastic neutron scattering studies of carbon materials derived from pyrolyzed epoxy novolak resins. His data supports the graphene sheet model and is also consistent with calculations of interior and edge carbon atoms in pyrene that chemically reacted with lithium.

Gerald, R. E., II; Chemical Engineering



Designed Chemical Intervention with Thiols for Prophylactic Contraception  

PubMed Central

Unlike somatic cells, sperm have several-fold more available-thiols that are susceptible to redox-active agents. The present study explains the mechanism behind the instant sperm-immobilizing and trichomonacidal activities of pyrrolidinium pyrrolidine-1-carbodithioate (PPC), a novel thiol agent rationally created for prophylactic contraception by minor chemical modifications of some known thiol drugs. PPC, and its three derivatives (with potential active-site blocked by alkylation), were synthesized and evaluated against live human sperm and metronidazole-susceptible and resistant Trichomonas vaginalis, in vitro. Sperm hexokinase activity was evaluated by coupled enzyme assay. PPC irreversibly immobilized 100% human sperm in ?30 seconds and totally eliminated Trichomonas vaginalis more efficiently than nonoxynol-9 and metronidazole. It significantly inhibited (P<0.001) thiol-sensitive sperm hexokinase. However, the molecule completely lost all its biological activities once its thiol group was blocked by alkylation. PPC was subsequently formulated into a mucoadhesive vaginal film using GRaS excipients and evaluated for spermicidal and microbicidal activities (in vitro), and contraceptive efficacy in rabbits. PPC remained fully active in quick-dissolving, mucoadhesive vaginal-film formulation, and these PPC-films significantly reduced pregnancy and fertility rates in rabbits. The films released ?90% of PPC in simulated vaginal fluid (pH 4.2) at 37°C in 5 minutes, in vitro. We have thus discovered a common target (reactive thiols) on chiefly-anaerobic, redox-sensitive cells like sperm and Trichomonas, which is susceptible to designed chemical interference for prophylactic contraception. The active thiol in PPC inactivates sperm and Trichomonas via interference with crucial sulfhydryl-disulfide based reactions, e.g. hexokinase activation in human sperm. In comparison to non-specific surfactant action of OTC spermicide nonoxynol-9, the action of thiol-active PPC is apparently much more specific, potent and safe. PPC presents a proof-of-concept for prophylactic contraception via manipulation of thiols in vagina for selective targeting of sperm and Trichomonas, and qualifies as a promising lead for the development of dually protective vaginal-contraceptive. PMID:23826278

Jain, Ashish; Verma, Vikas; Sharma, Vikas; Kushwaha, Bhavana; Lal, Nand; Kumar, Lalit; Rawat, Tara; Dwivedi, Anil K.; Maikhuri, Jagdamba P.; Sharma, Vishnu L.; Gupta, Gopal