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

Microsoft Academic Search

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

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



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.



Synthesis and characterization of new pyrrolidinium based protic ionic liquids. Good and superionic liquids.  


New pyrrolidinium-cation-based protic acid ionic liquids (PILs) were prepared through a simple and atom-economic neutralization reactions between pyrrolidine and Brønsted acids, HX, where X is NO 3 (-), HSO 4 (-), HCOO (-), CH 3COO (-) or CF 3COO (-) and CH 3(CH 2) 6COO (-). The thermal properties, densities, electrochemical windows, temperature dependency of dynamic viscosity and ionic conductivity were measured for these PILs. All protonated pyrrolidinium salts studied here were liquid at room temperature and possess a high ionic conductivity (up to 56 mS cm (-1)) at room temperature. Pyrrolidinium based PILs have a relatively low cost, a low toxicity and exhibit a large electrochemical window as compared to other protic ionic liquids (up 3 V). Obtained results allow us to classify them according to a classical Walden diagram and to determinate their "Fragility". Pyrrolidinium based PILs are good or superionic liquids and shows extremely fragility. They have wide applicable perspectives for fuel cell devices, thermal transfer fluids, and acid-catalyzed reaction media as replacements of conventional inorganic acids. PMID:18826270

Anouti, Mérièm; Caillon-Caravanier, Magaly; Dridi, Yosra; Galiano, Herve; Lemordant, Daniel



Volumetric properties, viscosity and refractive index of the protic ionic liquid, pyrrolidinium octanoate, in molecular solvents  

Microsoft Academic Search

Densities (?) and viscosities (?) of binary mixtures containing the Protic Ionic Liquid (PIL), pyrrolidinium octanoate with five molecular solvents: water, methanol, ethanol, n-butanol, and acetonitrile are determined at the atmospheric pressure as a function of the temperature and within the whole composition range. The refractive index of all mixtures (nD) is measured at 298.15K. The excess molar volumes VE

Mérièm Anouti; Annie Vigeant; Johan Jacquemin; Catherine Brigouleix; Daniel Lemordant



New functionalized ionic liquids based on pyrrolidinium and piperidinium cations with two ether groups as electrolytes for lithium battery  

Microsoft Academic Search

Four new functionalized ILs based on piperidinium and pyrrolidinium cations with two ether groups and TFSI? anion are synthesized and characterized. Physical and electrochemical properties of these ILs, including melting point, thermal stability, viscosity, conductivity and electrochemical stability, are investigated. All the ILs are liquids at room temperature, and the viscosities of P(2o1)2-TFSI and P(2o1)(2o2)-TFSI are 55 and 53mPas at

Shaohua Fang; Zhengxi Zhang; Yide Jin; Li Yang; Shin-ichi Hirano; Kazuhiro Tachibana; Shingo Katayama



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.

Domanska, Urszula



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

SciTech Connect

The quest for the development of rechargeable lithium-metal batteries has attracted vigorous worldwide research efforts because this system offers the highest theoretical specific energy [1]. For this to be achieved, the repetitive deposition and stripping of lithium must be close to fully reversible. Thus, alternative electrolytes have been investigated, such as the room-temperature ionic liquid (RTILs). Lithium can be cycled with a high degree of reversibility with efficiencies exceeding 99% using systems based on N-methyl N-alkyl pyrrolidinium (P{sub 1X}{sup +}) combined with the TFSI anion [2]. More recent efforts have been directed towards systems based on P{sub 1X}{sup +} cations with the FSI anion and appear to be even more promising [3,4]. In this work, we discuss to what extent RTILs based on P{sub 1X}{sup +} cations with TFSI or FSI anions can be used as electrolytes for rechargeable Li batteries. In particular, their physical and chemical properties are thoroughly discussed so as to explain the difference observed in their electrochemical behavior. Although these two systems seem to be stable against lithium, their compatibilities with cathode materials require full assessment as well. Thus, various manganese oxide cathodes are investigated in this study. Strategies to minimize cathode dissolution are also debated, such as the substitution of part of the manganese for titanium.

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



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.  


Room-temperature ionic liquids (RTIL, IL) are stable liquids composed of anions and cations. N-methyl-N-propyl-pyrrolidinium (P(13), Py(13), PYR(13), or mppy) is an important cation and produces stable ILs with various anions. In this study two amide-type anions, bis(trifluoromethanesulfonyl)amide [N(SO(2)CF(3))(2), TFSA, TFSI, NTf(2), or Tf(2)N] and bis(fluorosulfonyl)amide [N(SO(2)F)(2), FSA, or FSI], were investigated. In addition to P(13)-TFSA and P(13)-FSA, lithium salt doped samples were prepared (P(13)-TFSA-Li and P(13)-FSA-Li). The individual ion diffusion coefficients (D) and spin-lattice relaxation times (T(1)) were measured by (1)H, (19)F, and (7)Li NMR. At the same time, the ionic conductivity (?), viscosity (?), and density (?) were measured over a wide temperature range. The van der Waals volumes of P(13), 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 P(13)-TFSA and P(13)-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 P(13) and jump of a lithium ion are also discussed. PMID:21090866

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



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 1H, 19F, and 7Li 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



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



Photodetachment and electron reactivity in 1-methyl-1-butyl-pyrrolidinium bis(trifluoromethylsulfonyl)amide  

NASA Astrophysics Data System (ADS)

The transient absorption spectrum in the range 500 nm-1000 nm was measured with ultrafast time resolution on a flowing neat, aliphatic, room-temperature ionic liquid following anion photodetachment. In this region the spectrum was shown to be a combination of absorption from the electron and the hole. Spectrally-resolved electron quenching determined a bimodal shape for the hole spectrum in agreement with recent computational predictions on a smaller aliphatic ionic liquid [Margulis et al., J. Am. Chem. Soc. 133, 20186 (2011)]. For time delays beyond 15 ps, spectral evolution qualitatively agrees with recent radiolysis experiments [Wishart et al., Faraday Discuss. 154, 353 (2012)]. However, the shape of the spectrum is different, reflecting the contrast in ionization energy between the two methods. Previously unobserved reactivity of the electron was found with a time constant of 300 fs. The results demonstrate solvent control of the rate coefficient for reaction between the electron and proton, with a rapid decline in the rate within the first picosecond.

Molins i Domenech, Francesc; FitzPatrick, Benjamin; Healy, Andrew T.; Blank, David A.



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



An investigation into the electrophilic cyclisation of N-acyl-pyrrolidinium ions: a facile synthesis of pyrrolo-tetrahydroisoquinolones and pyrrolo-benzazepinones.  


The triflic acid-mediated cyclisation of N-arylmethyl- and N-arylethyl-acylpyrrolidinium ions gave moderate to good yields of pyrrolo-tetrahydroisoquinolones and pyrrolo-benzazepinones respectively. Electron-donating R substituents enhanced the rate of reaction and gave higher yields than electron-withdrawing substituents. Substituents on the methyl or ethyl chain in general enhanced the reaction, unless sterically encumbered. The equivalent acylpiperidinium ions cyclised much slower and in lower yield. PMID:19675913

King, Frank D; Aliev, Abil E; Caddick, Stephen; Copley, Royston C B



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



Novel room temperature molten salt electrolyte based on LiTFSI and acetamide for lithium batteries  

Microsoft Academic Search

A novel room temperature molten salt (RTMS) electrolyte composed of lithium bis(trifluoromethane sulfone)imide (LiN(SO2CF3)2, LiTFSI) and acetamide was found. Both LiTFSI and acetamide are solid at room temperature, but their mixture is a liquid at room temperature with a eutectic temperature of ?67 °C at a molar ratio of 1:4 (LiTFSI:Acetamide). The room temperature ionic conductivities of some compositions of

Yongsheng Hu; Hong Li; Xuejie Huang; Liquan Chen



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

Microsoft Academic Search

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 CO group

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



Comparative study of EC\\/DMC LiTFSI and LiPF 6 electrolytes for electrochemical storage  

Microsoft Academic Search

Lithium bis(trifluoromethane sulfonyl) imide (LiTFSI) salt are potentially a good alternative to LiPF6 since it could both improve the chemical and thermal stability as salt for electrolyte. This work presents a systematic comparative study between LiPF6 and LiTFSI in a mixture of EC\\/DMC on the basis of some of their physicochemical properties. Transport properties (viscosity and conductivity) are compared at

Mouad Dahbi; Fouad Ghamouss; François Tran-Van; Daniel Lemordant; Mérièm Anouti



Ionic liquid-based gel polymer electrolyte for LiMn 0.4Fe 0.6PO 4 cathode prepared by electrospinning technique  

Microsoft Academic Search

Two polymer electrolytes (PEs), one consisting of 1M LiPF6 in ethylene carbonate (EC)\\/dimethyl carbonate (DMC) (PEEC\\/DMC) and the other consisting of LiTFSI in room temperature ionic liquid (RTIL), 1-ethyl-3-methyl imidazolium bis(trifluoromethane sulfonyl)imide (EMITFSI) (PEIL), were prepared by using electrospun P(VdF-HFP) membranes. The PEs showed typical impedance spectroscopic responses with high conductivity and good anodic stability. The PEs were applied with

Jae-Kwang Kim; James Manuel; Ghanshyam S. Chauhan; Jou-Hyeon Ahn; Ho-Suk Ryu



Performance evaluation of PVdF gel polymer electrolytes  

Microsoft Academic Search

A series of gel polymer electrolytes containing PVdF as homo polymer, a mixture of 1:1 Ethylene Carbonate (EC) : Propylene\\u000a Carbonate (PC) as plasticizer and lithium-bistrifluoromethane sulphone imide [imide — LiN (CF3SO2)2] has been developed. Amounts of polymer (PVdF), plasticizer and the imide lithium salt have been varied as a function of\\u000a their weight ratio composition in this regard. Dimensionally

P. Periasamy; K. Tatsumi; N. Kalaiselvi; M. Shikano; T. Fiyieda; Y. Saito; T. Sakai; M. Mizukata; A. Kajinami; S. Deki



Tuning ionic liquids for hydrate inhibition.  


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

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



Synthesis of cationic dibenzosemibullvalene-based phase-transfer catalysts by di-?-methane rearrangements of pyrrolinium-annelated dibenzobarrelene derivatives  

PubMed Central

Summary Dibenzobarrelene derivatives, that are annelated with a pyrrolinium unit [N,N-dialkyl-3,4-(9',10'-dihydro-9',10'-anthraceno-3-pyrrolinium) derivatives], undergo a photo-induced di-?-methane rearrangement upon triplet sensitization to give the corresponding cationic dibenzosemibullvalene derivatives [N,N-dialkyl-3,4-{8c,8e-(4b,8b-dihydrodibenzo[a,f]cyclopropa[cd]pentaleno)}pyrrolidinium derivatives]. Whereas the covalent attachment of a benzophenone functionality to the pyrrolinium nitrogen atom did not result in an internal triplet sensitization, the introduction of a benzophenone unit as part of the counter ion enables the di-?-methane rearrangement of the dibenzobarrelene derivative in the solid-state. Preliminary experiments indicate that a cationic pyrrolidinium-annelated dibenzosemibullvalene may act as phase-transfer catalyst in alkylation reactions.

Luo, Jia



Liquid densities, heat capacities, refractive index and excess quantities for {protic ionic liquids + water} binary system  

Microsoft Academic Search

Densities, ?, of aqueous solutions of the room temperature protic ionic liquid (PIL), pyrrolidinium nitrate are determined at the atmospheric pressure over the temperature range from (283.15 to 323.15)K and within the whole composition range. The molar isobaric heat capacities, Cp, and refractive index, nD, of {PIL+water} binary system are measured at 298.15K. The excess molar volumes VE, excess molar

Mérièm Anouti; Magaly Caillon-Caravanier; Yosra Dridi; Johan Jacquemin; Christopher Hardacre; Daniel Lemordant



Electron solvation dynamics and reactivity in ionic liquids observed by picosecond radiolysis techniques.  


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. PMID:22455029

Wishart, James F; Funston, Alison M; Szreder, Tomasz; Cook, Andrew R; Gohdo, Masao



Room Temperature Ionic Liquids for Separating Organics from Produced Water  

Microsoft Academic Search

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

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



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.



Room temperature lithium polymer batteries based on ionic liquids  

Microsoft Academic Search

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

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



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


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. Compared with the AC/S composite, the NC/S composite showed enhanced activity toward sulfur reduction, as evidenced by the lower onset sulfur reduction potential, higher redox current density in the CV test, and faster charge-transfer kinetics, as indicated by EIS measurements. At room temperature under a current density of 84 mA g(-1) (C/20), the battery based on the NC/S composite exhibited a higher discharge potential and an initial capacity of 1420 mAh g(-1), whereas the battery based on the AC/S composite showed a 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; capacity fading can be improved by further cathode modification. PMID:22847977

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



An MD study of the applicability of the Walden rule and the Nernst-Einstein model for ionic liquids.  


Six different ionic liquids containing imidazolium, pyrrolidinium and ammonium cations paired with bis[(trifluoromethyl)sulfonyl]imide and bis[(perfluoroethyl)sulfonyl]imide anions were studied using molecular dynamics simulations. Ionic conductivities, shear viscosities and self-diffusivities were computed and compared to see what relationships exist between these three transport properties. The simulations suggest that these ionic liquids follow closely the Walden rule, which relates ionic conductivity to fluidity. The computed ionic conductivities agree well with those predicted from the Nernst-Einstein model, suggesting that long-time correlation among ion velocities is small, or that the "ionicity" of these ionic liquids is high. PMID:22378767

Liu, Hongjun; Maginn, Edward



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


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

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



Effect of lithium ions on oxygen reduction in ionic liquid-based electrolytes  

Microsoft Academic Search

The effect of lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) on the oxygen redox reaction (ORR) in several pyrrolidinium-based ionic liquids (ILs) is investigated by cyclic voltammetry. The results are compared to those found with LiTFSI-tetraglyme and LiTFSI-1,3-dimethyl-3,4,5,6-tetrahydro-2(1H)-pyrimidone solutions. The effect of the addition of tris(pentafluorophenyl) borane (TPFPB) to IL-LiTFSI solutions is also investigated. The results demonstrate that the presence of 0.1M Li+ renders

Francesca De Giorgio; Francesca Soavi; Marina Mastragostino



Transport properties investigation of aqueous protic ionic liquid solutions through conductivity, viscosity, and NMR self-diffusion measurements.  


We present a study on the transport properties through conductivity (?), viscosity (?), and self-diffusion coefficient (D) measurements of two pure protic ionic liquids--pyrrolidinium hydrogen sulfate, [Pyrr][HSO(4)], and pyrrolidinium trifluoroacetate, [Pyrr][CF(3)COO]--and their mixtures with water over the whole composition range at 298.15 K and atmospheric pressure. Based on these experimental results, transport mobilities of ions have been then investigated in each case through the Stokes-Einstein equation. From this, the proton conduction in these PILs follows a combination of Grotthuss and vehicle-type mechanisms, which depends also on the water composition in solution. In each case, the displacement of the NMR peak attributed to the labile proton on the pyrrolidinium cation with the PILs concentration in aqueous solution indicates that this proton is located between the cation and the anion for a water weight fraction lower than 8%. In other words, for such compositions, it appears that this labile proton is not solvated by water molecules. However, for higher water content, the labile protons are in solution as H(3)O(+). This water weight fraction appears to be the solvation limit of the H(+) ions by water molecules in these two PILs solutions. However, [Pyrr][HSO(4)] and [Pyrr][CF(3)COO] PILs present opposed comportment in aqueous solution. In the case of [Pyrr][CF(3)COO], ?, ?, D, and the attractive potential, E(pot), between ions indicate clearly that the diffusion of each ion is similar. In other words, these ions are tightly bound together as ion pairs, reflecting in fact the importance of the hydrophobicity of the trifluoroacetate anion, whereas, in the case of the [Pyrr][HSO(4)], the strong H-bond between the HSO(4)(-) anion and water promotes a drastic change in the viscosity of the aqueous solution, as well as on the conductivity which is up to 187 mS·cm(-1) for water weight fraction close to 60% at 298 K. PMID:22404286

Anouti, Mérièm; Jacquemin, Johan; Porion, Patrice



Physical Properties of Ionic Liquids Consisting of the 1-Butyl-3-Methylimidazolium Cation with Various Anions and the Bis(trifluoromethylsulfonyl)imide Anion with Various Cations  

SciTech Connect

Physical properties of 4 room-temperature ionic liquids consisting of the 1-butyl-3-methylimidazolium cation with various perfluorinated anions and the bis(trifluoromethylsulfonyl)imide (Tf2N-) anion with 12 pyrrolidinium-, ammonium-, and hydroxyl-containing cations are reported. Electronic structure methods are used to calculate properties related to the size, shape, and dipole moment of individual ions. Experimental measurements of phase-transition temperatures, densities, refractive indices, surface tensions, solvatochromic polarities based on absorption of Nile Red, 19F chemical shifts of the Tf2N- anion, temperature-dependent viscosities, conductivities, and cation diffusion coefficients are reported. Correlations among the measured quantities as well as the use of surface tension and molar volume for estimating Hildebrand solubility parameters of ionic liquids are also discussed.

Jin, Hui [Pennsylvania State University, University Park, PA; O'Hare, Bernie [Pennsylvania State University, University Park, PA; Dong, Jing [Pennsylvania State University, University Park, PA; Arzhantsev, Sergei [Pennsylvania State University, University Park, PA; Baker, Gary A [ORNL; Wishart, James F. [Brookhaven National Laboratory (BNL); Benesi, Alan [Pennsylvania State University, University Park, PA; Maroncelli, Mark [Pennsylvania State University, University Park, PA



A comparison of phosphorus and fluorine containing IL lubricants for steel on aluminium.  


Ionic liquids have been shown to be highly effective lubricants for a steel on aluminium system. This work shows that the chemistry of the anion and cation are critical in achieving maximum wear protection. The performance of the ILs containing a diphenylphosphate (DPP) anion all showed low wear, as did some of the tris(pentafluoroethyl)trifluorophosphate (FAP) and bis(trifluoromethanesulfonyl)amide (NTf(2)) anion containing ILs. However, in the case of the FAP and NTf(2) based systems, a cation dependence was observed, with relatively poor wear resistance obtained in the case of an imidazolium FAP and two pyrrolidinium NTf(2) salts, probably due to tribocorrosion caused by the fluorine reaction with the aluminium substrate. The systems exhibiting poor performance generally had a lower viscosity, which also impacts on their tribological properties. Those ILs that exhibited low wear were shown to have formed protective tribofilms on the aluminium alloy surface. PMID:22555280

Somers, Anthony E; Biddulph, Shannon M; Howlett, Patrick C; Sun, Jiazeng; MacFarlane, Douglas R; Forsyth, Maria



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

PubMed Central

Quartz crystal microbalance with dissipation (QCM-D) monitoring and atomic force microscopy (AFM) were combined to evaluate the defects created by an ionic liquid anion and a cation in a supported phospholipid bilayer composed of zwitterionic lipids on a silica surface. The cation 1-octyl-3-methyl imidazolium (OMIM+) was shown to remove lipids from the bilayer, increase the roughness to approximately 2.8 nm (~0.2 for stable supported bilayer) and possibly redeposit lipids with entrapped water. The anion bis(trifluoromethylsulfonyl)imide (Tf2N-) was found to leave distinct defects within the bilayer that had large pore-like interiors which left the surrounding bilayer intact. However, the ionic liquid 1-butyl-1-methyl pyrrolidinium bis(trifluoromethylsulfonyl)imide (BMP-Tf2N) formed a film over the supported bilayer. This work demonstrates, for the first time, the direct effects common components of ionic liquids have on a supported phospholipids bilayer.

Evans, Kervin O.



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



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.



Ionic liquids as lubricants or lubrication additives: an ecotoxicity and biodegradability assessment.  


This paper reports on the (eco)toxicity and biodegradability of ionic liquids considered for application as lubricants or lubrication additives. Ammonium- and pyrrolidinium-based cations combined with methylsulphate, methylsulphonate and/or (CF(3)SO(2))(2)N(-) anions were investigated in tests to determine their aquatic toxicity using water fleas Daphnia magna, green algae Selenastrum capricornutum and marine bacteria (Vibrio fischeri). Additional test systems with an isolated enzyme (acetylcholinesterase) and isolated leukaemia cells from rats (IPC-81) were used to assess the biological activity of the ionic liquids. These compounds generally exhibit low acute toxicity and biological activity. Their biodegradability was screened according to OECD test procedures 301 B and 301 F. For choline and methoxy-choline ionic liquids ready biodegradability was observed within 5 or 10 d, respectively. Some of the compounds selected have a considerable potential to contribute to the development of more sustainable products and processes. PMID:22749125

Stolte, Stefan; Steudte, Stephanie; Areitioaurtena, Olatz; Pagano, Francesco; Thöming, Jorg; Stepnowski, Piotr; Igartua, Amaya



Pseudocapacitive mechanism of manganese oxide in 1-ethyl-3-methylimidazolium thiocyanate ionic liquid electrolyte studied using X-ray photoelectron spectroscopy.  


The electrochemical behavior of anodically deposited manganese oxide was studied in pyrrolidinium formate (P-HCOO), 1-butyl-3-methylimidazolium hexafluorophosphate (BMI-PF6), and 1-ethyl-3-methylimidazolium thiocyanate (EMI-SCN) ionic liquids (ILs). The experimental data indicate that the Mn oxide electrode showed ideal pseudocapacitive performance in aprotic EMI-SCN IL. In a potential window of approximately 1.5 V, the oxide specific capacitance, evaluated using cyclic voltammetry and chronopotentiometry, was about 55 F/g. The electrochemical energy storage reaction was examined using X-ray photoelectron spectroscopy (XPS). It was confirmed that the SCN- anions, instead of the EMI+ cations, were the primary working species that can become incorporated into the oxide and thus compensate the Mn3+/Mn4+ valent state variation upon the charge-discharge process. According to the analytical results, a pseudocapacitive mechanism of Mn oxide in the SCN- based aprotic IL was proposed. PMID:19621902

Chang, Jeng-Kuei; Lee, Ming-Tsung; Tsai, Wen-Ta; Deng, Ming-Jay; Cheng, Hui-Fang; Sun, I-Wen



Selective quenching of 2-naphtholate fluorescence by imidazolium ionic liquids.  


The effect of addition of water-miscible ionic liquids (ILs), 1-butyl-3-methylimidazolium tetrafluoroborate ([bmim][BF(4)]), 1-butyl-3-methylimidazolium trifluoromethanesulfonate ([bmim][OTf]), and 1-butyl-1-methylpyrrolidinium trifluoromethanesulfonate ([bmpyrr][OTf]), on photophysical properties of 2-naphthol in water at various pHs is reported. Electronic absorbance behavior of 2-naphthol dissolved in aqueous mixtures of ILs is observed to be similar to that found in water at different pHs. The excited-state properties, however, are changed dramatically as the IL is added to the milieu. The presence of imidazolium IL results in significant quenching of the fluorescence emission from 2-naphtholate. On the contrary, pyrrolidinium IL does not quench the fluorescence from the anionic species. The quenching of 2-naphtholate fluorescence by aromatic imidazolium cations in aqueous IL mixtures is found to follow simple Stern-Volmer behavior. The aromatic imidazolium cation acts as an electron/charge acceptor during the quenching process where formation of a weakly fluorescent complex between the imidazolium cation and the excited 2-naphtholate anion possibly involving the acidic C2 proton of imidazolium is proposed. Because of the absence of such an acidic proton, the nonaromatic pyrrolidinium cation is not able to form a complex with the excited 2-naphtholate and cannot act as an electron/charge acceptor. Excited-state emission intensity decay data further corroborate this hypothesis as the intensity decay fits well to a single-exponential decay with no change in recovered lifetimes as [bmpyrr][OTf] is added; a double-exponential decay is required to satisfactorily fit the decay data in the presence of [bmim][BF(4)], hinting at the presence of a weakly fluorescent complex. The uniqueness of ILs in affecting excited-state properties of the 2-naphthol system is demonstrated through comparison with NaBF(4), NaCl, and polyethylene glycol with an average molecular weight of 200, respectively, as additives. PMID:22953779

Kumar, Vinod; Pandey, Siddharth



Antimicrobial membrane cellulose acetate containing ionic liquid and metal nanoparticles.  


Stable metallic Au(0), Ag(0) and Pt(0) nanoparticle-containing membrane films (20 microm thickness) were obtained by combining irregularly shaped nanoparticles of monomodal size distributions (11 +/- 1.5 nm Au(0), 8.9 +/- 2.1 nm Ag(0) and 2.8 +/- 0.4 nm Pt(0)) in the ionic liquid (IL) 1-n-butyl-3-methylimidazolium bis(trifluoromethane sulfonyl)imide (BMI x (NTf)2) with a syrup of cellulose acetate (CA) in acetone. The presence of small and stable Au(0), Ag(0) or Pt(0) nanoparticles induced an augmentation in the CA/IL film surface areas. The addition of the IL to the membrane resulted in an increase of its elasticity and a decrease in its tenacity and toughness, whereas its stress at break was not influenced. High antimicrobial activity was observed in membranes containing Au(0), Ag(0) and Pt(0) metal concentrations as low as 1 mg of metal per 5 g of CA. The CA/IL/nanoparticle combination enhanced the activity and durability of the metal nanoparticles and provided greater antimicrobial activity against E. coli and S. aureus bacteria. PMID:21770152

Scheeren, Carla W; Hermes, Vanessa; Bianchi, Otávio; Hertz, Plinho F; Dias, Silvio L P; Dupont, Jairton



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



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



Ion conduction in phosphonium-polysiloxane ionomers  

NASA Astrophysics Data System (ADS)

Low Tg ionomers with phosphonium cations covalently attached as side chains have potential application in energy conversion and storage devices. For example, alkaline fuel cells rely on membranes that transport hydroxide anions and some advanced batteries rely on membranes transporting fluoride anions. To better understand ion conduction in phosphonium-polysiloxane ionomers, allyl tributyl phosphonium bromide monomer was synthesized and, along with a vinyl ethylene oxide monomer, attached to polymethylhydrosiloxane by hydrosilylation. These ionomers maintain low Tg -74 ^oC with up to 10 mol% phosphonium and are fully water soluble, allowing easy anion exchange and purification. We report dielectric spectroscopy results for these ionomers with a variety of counter-anions. Electrode polarization at low frequencies is analyzed to determine the number density of simultaneously conducting counter ions and their mobility. This analysis reveals higher mobility and lower activation energy for conducting anions that are larger and more diffuse, such as bis(trifluoromethane sulfonyl)imide, contributing to better performance as anion-conducting membranes.

Liang, Siwei; Hyeok Choi, U.; Runt, James; Colby, Ralph



Soft glassy colloidal arrays in an ionic liquid: colloidal glass transition, ionic transport, and structural color in relation to microstructure.  


The colloidal glass transition, ionic transport, and optical properties of soft glassy colloidal arrays (SGCAs) that consist of poly(methyl methacrylate) (PMMA)-grafted silica nanoparticles (PMMA-g-NPs) and a room-temperature ionic liquid, 1-ethyl-3-methylimidazolium bis(trifluoromethane sulfonyl)amide ([C(2)mim][NTf(2)]), were investigated. At lower particle concentrations, PMMA-g-NPs were well-suspended in the IL without any aggregation or sedimentation, and the dilute suspensions showed liquid-like behavior. However, above a certain particle concentration, the suspensions became solidified and exhibited different structural colors depending on the particle concentrations. The liquid-solid transition of the SGCAs was essentially caused by colloidal glass transition. Due to the soft repulsive interaction between the particles, the effective volume fraction of the particle (?(eff)) required for colloidal glass transition was higher than that of the hard sphere system and found to be approximately 0.70-0.74. The SGCA had sufficient ionic conductivity, which was greater than 10(-3) S cm(-1) at room temperature, even in the highly concentrated region. For ionic transport of the cation and the anion in the SGCAs, the decrease in diffusivity observed with the addition of the particles (D(g)/D(0)) was slightly greater for the [NTf(2)] anion than that of the [C(2)mim] cation, suggesting that the [NTf(2)] anion preferentially interacts with the PMMA chains. The SGCAs showed homogeneous, nonbrilliant, and angle-independent structural colors above the glass transition volume fraction. In addition, the color of the SGCAs changed from red to green to blue as the particle concentration increased. A linear relationship was found between the maximum wavelength of the reflection spectra and the center-to-center distance in the SGCAs. PMID:20879726

Ueno, Kazuhide; Sano, Yuta; Inaba, Aya; Kondoh, Masashi; Watanabe, Masayoshi



Density, viscosity and electrical conductivity of protic alkanolammonium ionic liquids.  


Ionic liquids are molten salts with melting temperatures below the boiling point of water, and their qualification for applications in potential industrial processes does depend on their fundamental physical properties such as density, viscosity and electrical conductivity. This study aims to investigate the structure-property relationship of 15 ILs that are primarily composed of alkanolammonium cations and organic acid anions. The influence of both the nature and number of alkanol substituents on the cation and the nature of the anion on the densities, viscosities and electrical conductivities at ambient and elevated temperatures are discussed. Walden rule plots are used to estimate the ionic nature of these ionic liquids, and comparison with other studies reveals that most of the investigated ionic liquids show Walden rule values similar to many non-protic ionic liquids containing imidazolium, pyrrolidinium, tetraalkylammonium, or tetraalkylphosphonium cations. Comparison of literature data reveals major disagreements in the reported properties for the investigated ionic liquids. A detailed analysis of the reported experimental procedures suggests that inappropriate drying methods can account for some of the discrepancies. Furthermore, an example for the improved presentation of experimental data in scientific literature is presented. PMID:21298175

Pinkert, André; Ang, Keng L; Marsh, Kenneth N; Pang, Shusheng



Correlating the structure and composition of ionic liquids with their toxicity on Vibrio fischeri: A systematic study.  


A systematic screening of the toxicity of ionic liquids (IL) towards Vibrio fischeri, a bioluminescent marine bacteria generally used in ecotoxicological bioassays, was carried out. The objectives of this work were to find hydrophilic or hydrophobic low toxicity IL and to investigate structure-toxicity relationship of IL. Toxicity of 54 IL to V. fischeri have been measured, some referring to new IL based on quinuclidinol or tropinol and some to generic IL (i.e., imidazolium, pyridinium, pyrrolidinium or piperidinium). For 47 of them, toxicity values have not been reported elsewhere. Water-soluble IL containing hydrophilic anions halide, thiocyanate, dicyanamide, trifluoromethansulfonate were studied. Some IL were found to exhibit very low toxicity towards V. fisheri. Hydrophobic IL based on bis(trifluoromethanesulfonyl)imide, tetrafluoroborate tetraphenylborate and tetracyanoborate were also studied. Toxicity was measured in a consistent way starting from aqueous solutions saturated with IL. The least toxic hydrophobic IL found in this study was [EMIM][B(CN)(4)]. A multifactorial analysis was found to be convenient for finding relevant structure parameters influencing the toxicity of IL. From this analysis, the planarity of the cation ring appeared to be a relevant parameter. Finally, good linear correlations were found when toxicity of IL was plotted either against the number of aliphatic carbons surrounding a pyridinium cation or the total number of carbons of a cation. PMID:22417395

Viboud, Sylvie; Papaiconomou, Nicolas; Cortesi, Aurélien; Chatel, Grégory; Draye, Micheline; Fontvieille, Dominique



Comparative effects of bepridil, its quaternary derivative CERM 11888 and verapamil on caffeine-induced contracture in ferret hearts.  

PubMed Central

1. The effects of bepridil, its quaternary derivative: CERM 11888 (methyl-pyrrolidinium bromide) (10(-7)-10(-5) M), and verapamil (10(-7)-10(-6) M) were compared on caffeine-induced contracture of isolated ventricular trabeculae of the ferret. 2. Bepridil diminished the amplitude of contracture in a concentration-dependent fashion, and this effect was significantly different from that of CERM 11888 which, like verapamil, only reduced the amplitude at the highest concentration used. 3. Bepridil (10(-6) M) significantly shortened the time to peak tension and accelerated the relaxation phase of contracture. This latter effect was different from that of CERM 11888. Verapamil (10(-6) M) also tended to accelerate the relaxation phase. At 10(-5) M these actions of bepridil on the time to peak and relaxation tended to reverse. 4. At all concentrations bepridil and verapamil reduced the rate of repriming of contracture and this effect of bedpridil was significantly different from that of its quaternary derivative which only showed a significant effect at 10(-5) M. 5. These results demonstrate a clear intracellular effect of bepridil in the ferret heart. Verapamil and CERM 11888 had only weak intracellular effects even at high concentrations. 6. Analysis of the results suggests that the main sites of action of bepridil in this model are the sarcoplasmic reticulum and one or two calcium compartments in the sarcolemma.

Leboeuf, J.; Leoty, C.; Lamar, J. C.; Massingham, R.



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


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

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



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

SciTech Connect

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

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



Synthesis and Structure Solution of Zeolite SSZ-65  

SciTech Connect

This report describes the synthesis and structure solution of the new zeolite SSZ-65. SSZ-65 may be prepared as either a borosilicate (Si52.5B1.5O108) or an aluminosilicate using 1-[1-(4-chloro-phenyl)-cyclopropylmethyl]-1-ethyl-pyrrolidinium as a structure-directing agent. The structure of SSZ-65 was determined with the FOCUS Fourier recycling method. The framework of SSZ-65 possesses a two-dimensional system of intersecting 12-ring channels with pore apertures of 6.9 Angstroms x 5.9 Angstroms . The topological symmetry of SSZ-65 is P6/mmm, but improvements in the Rietveld refinement of the powder diffraction data are obtained in space group P6/m (a = 16.8009(2) Angstroms and c = 12.6154(1) Angstroms ). The agreement values improve from Rwp = 0.116, Rp = 0.094, and R(F2) = 0.142 in P6/mmm to Rwp = 0.103, Rp = 0.085, and R(F2) = 0.092 in P6/m.

Elomari,S.; Burton, A.; Ong, K.; Pradhan, A.; Chan, I.



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



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



Effects of some isomers and analogues of nicotine on junctional transmission  

PubMed Central

A number of isomers and homologues of nicotine, (2-, 3- and 4-pyridylmethyl)- and [2-(2-, 3- and 4-pyridyl)ethyl]- dialkylamines and trialkylammonium salts, have been prepared. They have been tested for their ability to act like acetylcholine in causing contracture of the chick biventer-cervicis and, some of them, for their ability to stimulate the superior cervical ganglion of the cat, causing contracture of the nictitating membrane. All the compounds have been tested for their ability to block transmission on the superior cervical ganglion of the cat and on the rat diaphragm preparation, and most of them for ability to inhibit the enzymatic hydrolysis of acetylcholine, using an acetone-powder of dog caudate nucleus as a source of acetylcholinesterase. The dissociation constants of the compounds have been measured by electrometric titration. The dissociation constants were used to compute the amount of monovalent ion present in the conditions of the biological tests, and the activities of the compounds have, accordingly, been compared on an ionic, as well as on a molecular, basis. The two sets of figures do not differ greatly. Trimethyl[2-(3-pyridyl)ethyl]ammonium (23) was the most potent compound on the chick and cat preparations. On an ionic basis (that is, compared with the monovalent nicotinium ion) this was 2.6 times as active as nicotine on the chick biventer and 11 times as active on the cat superior cervical ganglion. On the rat diaphragm it was 7.1 times as active as nicotine and less active than 1-methyl-1-(3-pyridylmethyl)-pyrrolidinium (26) (9.5 times the nicotinium ion) and trimethyl(4-pyridylmethyl)-ammonium (21) (11 times). The relationships between structure and dissociation constant, anticholinesterase activity, and activity in the pharmacological tests have been discussed.

Barlow, R. B.; Hamilton, J. T.



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



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


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. PMID:22248909

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



The Influence of receptor kinetics on the onset and duration of action and the therapeutic index of NVA237 and tiotropium.  


Studies under nonphysiological conditions suggest that long receptor residency time is responsible for the 24-h duration of action of the long-acting muscarinic antagonist (LAMA) tiotropium. Our aim was to determine how clinically relevant dissociation rates under more physiological conditions influence the differences in onset of action between tiotropium and 3-[(cyclopentylhydroxyphenylacetyl oxy]-1,1-dimethyl-pyrrolidinium bromide (NVA237), a once-daily dry-powder formulation of the LAMA glycopyrronium bromide in development for chronic obstructive pulmonary disease. In addition, we have investigated kinetic selectivity at each of the muscarinic receptor subtypes to determine whether the improved cardiovascular therapeutic index obtained with NVA237 in animal models is attributable to differences in kinetic rate constants. The binding of radioligand [3H]N-methyl-scopolamine was measured in the presence/absence of several concentrations of unlabeled competitors, and data were analyzed using a competition kinetic model to provide on/off rates for the competitor. We found shorter dissociation half-lives for NVA237 and tiotropium under physiological (11.4 and 46.2 min, respectively) versus nonphysiological conditions (173 and 462 min, respectively). NVA237 had a more rapid onset of action (3-4.8 times) versus tiotropium, determined in an vitro calcium and rat tracheal strip assay. Simulations suggested that the more rapid onset of NVA237 action could be explained by differences in kinetic parameters. NVA237 had greater equilibrium binding and kinetic selectivity for muscarinic type 3 (M3) versus muscarinic type 2 (M2) receptors, with a faster off rate from M2 versus M3 receptors than tiotropium, potentially affording it a more favorable therapeutic index. This study suggests that the 24-h duration of action of NVA237 and tiotropium is not solely the result of their slow dissociation from the M3 receptor and highlights the importance of conducting in vitro experiments in conditions reflecting those in vivo. PMID:22854200

Sykes, David A; Dowling, Mark R; Leighton-Davies, Juliet; Kent, Toby C; Fawcett, Lindsay; Renard, Emilie; Trifilieff, Alexandre; Charlton, Steven J



Aqueous biphasic systems composed of ionic liquids and sodium carbonate as enhanced routes for the extraction of tetracycline.  


Aqueous biphasic systems (ABS) using ionic liquids (ILs) offer an alternative approach for the extraction, recovery, and purification of biomolecules through their partitioning between two aqueous liquid phases. In this work, the ability of a wide range of ILs to form ABS with aqueous solutions of Na2 CO3 was evaluated. The ABS formed by IL?+?water?+?Na2 CO3 were determined at 25°C, and the respective solubility curves, tie-lines, and tie-line lengths are reported. The studied ILs share the common chloride anion, allowing the IL cation core, the cation isomerism, the presence of functionalized groups, and alkyl side chain length effects to be evaluated. An increase in the cation side alkyl chain length leads to a higher ability for liquid-liquid demixing whereas different positional isomers and the presence of an allyl group have no major influence in the phase diagrams behavior. Quaternary phosphonium- and ammonium-based fluids are more able to form an ABS when compared with imidazolium-, pyridinium-, pyrrolidinium-, and piperidium-based ILs. Moreover, the presence of an aromatic cation core has no major contribution to the formation of ABS when compared to the respective nonaromatic counterparts. Finally, to appraise on the systems applicability in downstream processing, selected systems were used for the partitioning of tetracyclines (neutral and salt forms) - a class of antibiotics produced by bacteria fermentation. Single-step extraction efficiencies for the IL-rich phase were always higher than 99% and confirm the great potential of ILs to be applied in the biotechnological field. PMID:23420737

Marques, Carlos F C; Mourão, Teresa; Neves, Catarina M S S; Lima, Alvaro S; Boal-Palheiros, Isabel; Coutinho, João A P; Freire, Mara G



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.

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