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Sample records for 1-hexyl-3-methylimidazolium hexafluorophosphate c6mimpf6

  1. Dynamical properties of alcohol + 1-hexyl-3-methylimidazolium ionic liquid mixtures: a computer simulation study.

    PubMed

    Méndez-Morales, Trinidad; Carrete, Jesús; García, Manuel; Cabeza, Oscar; Gallego, Luis J; Varela, Luis M

    2011-12-29

    In this work, extensive molecular dynamics simulations of the dynamics of mixtures of ionic liquids (ILs) composed of the cation 1-hexyl-3-methylimidazolium and several anions of different hydrophobicity degrees (Cl(-), BF(4)(-), PF(6)(-)) with alcohols of different chain lengths (methanol and ethanol) are reported. We evaluated the influence of the nature of the anion, the length of the molecular chain of the alcohol, and the alcohol concentration on some dynamical properties of the mixtures, such as self-diffusion coefficients of all the species, mean square displacements (with an analysis of both ballistic and diffusive regimes), and velocity autocorrelation functions of alcohol molecules. The diffusivity of the mixtures was found to be highly dependent on the nature of the anion since the interaction between chloride and alcohols is greater than that with fluorinated anions and leads to slower dynamics. Additionally, our results show that self-diffusion coefficients increase with alcohol concentration. On the other hand, a subdiffusive regime over thousands of picoseconds was detected at intermediate times through analysis of the center-of-mass mean square displacements of alcohol molecules, a region that becomes narrower as alcohol concentration increases. Finally, the study of the role of the anion and of solvent concentration on velocity autocorrelation functions reflects an increase in mean collision times as the amount of alcohol increases until the value of pure alcohols is reached. These collision times are smaller in mixtures with halogenated ILs.

  2. Low-temperature heat capacity of room-temperature ionic liquid, 1-hexyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide.

    PubMed

    Shimizu, Yoshitaka; Ohte, Yoko; Yamamura, Yasuhisa; Saito, Kazuya; Atake, Tooru

    2006-07-20

    Heat capacities of liquid, stable crystal, and liquid-quenched glass of a room-temperature ionic liquid (RTIL), 1-hexyl-3-methylimidazolium bis(trifluromethylsulfonyl)imide were measured between 5 and 310 K by adiabatic calorimetry. Heat capacity of the liquid at 298.15 K was determined for an IUPAC project as (631.6 +/- 0.5) J K(-1) mol(-1). Fusion was observed at T(fus) = 272.10 K for the stable crystalline phase, with enthalpy and entropy of fusion of 28.34 kJ mol(-1) and 104.2 J K(-1) mol(-1), respectively. The purity of the sample was estimated as 99.83 mol % by the fractional melting method. The liquid could be supercooled easily and the glass transition was observed around T(g) approximately 183 K, which was in agreement with the empirical relation, T(g) approximately ((2)/(3)) T(fus). The heat capacity of the liquid-quenched glass was larger than that of the crystal as a whole. In the lowest temperature region, however, the difference between the two showed a maximum around 6 K and a minimum around 15 K, at which the heat capacity of the glass was a little smaller than that of crystal.

  3. Molecular dynamics simulations of the liquid surface of the ionic liquid 1-hexyl-3-methylimidazolium bis(trifluoromethanesulfonyl)amide: structure and surface tension.

    PubMed

    Sanmartín Pensado, Alfonso; Malfreyt, Patrice; Pádua, Agílio A H

    2009-11-05

    Molecular dynamics simulations of the liquid-vacuum interface of the ionic liquid 1-hexyl-3-methylimidazolium bis(trifluoromethylsulfonyl)amide were performed with an all-atom force field. Structural properties of the interface, such as orientational ordering and density profiles, were calculated. The hexyl side chain of the cation is likely to protrude outward from the surface layer. There is a region with enhanced density from that of the bulk where the cation preferably slants with the imidazolium ring tending to be perpendicular to the interface. The surface tensions are calculated using mechanical and thermodynamic definitions via profiles along the direction normal to the interface. We also discuss the different contributions to the surface tension due to the repulsion-dispersion and electrostatic interactions. The use of local pressure profiles provides an explanation to the systematic problems encountered by several researchers to obtain accurate values of the surface tension at low temperature. Even when macroscopically the system looks in equilibrium, locally this is not accomplished.

  4. Ultrafast transient absorption spectrum of the room temperature Ionic liquid 1-hexyl-3-methylimidazolium bromide: Confounding effects of photo-degradation

    NASA Astrophysics Data System (ADS)

    Musat, Raluca M.; Crowell, Robert A.; Polyanskiy, Dmitriy E.; Thomas, Marie F.; Wishart, James F.; Katsumura, Yosuke; Takahashi, Kenji

    2015-12-01

    The photochemistry of the charge transfer (CT) band of the room temperature ionic liquid (RTIL) 1-hexyl-3-methylimidazolium bromide (HMIm+/Br-) is investigated using near-IR to vis ultrafast transient absorption (TA) and steady-state UV absorption spectroscopies. Continuous irradiation of the CT band at 266 nm results in the formation of photo-products that absorb strongly at 266 nm. It is shown that these photo-products, which are apparently very stable, adversely affect ultrafast TA measurements. Elimination of these effects reveals at least two transient species that exist within the TA detection window of 100 fs to 3 ns and 500-1250 nm. One of the components is a short-lived (<1 ps) species that absorbs at 1080 nm. The second band exhibits a multicomponent spectrum that is very broad with an absorption maximum around 600 nm and a lifetime that is longer than the 3 ns window of our TA spectrometer. Within the signal to noise ratio of the TA spectrometer little to no solvated electron is generated by the CT mechanism.

  5. Thermodynamic Properties at Saturation Derived from Experimental Two-Phase Isochoric Heat Capacity of 1-Hexyl-3-methylimidazolium bis[(trifluoromethyl)sulfonyl]imide

    NASA Astrophysics Data System (ADS)

    Polikhronidi, Nikolai G.; Batyrova, Rabiyat G.; Abdulagatov, Ilmutdin M.; Magee, Joseph W.; Wu, Jiangtao

    2016-11-01

    New measurements are reported for the isochoric heat capacity of the ionic liquid substance 1-hexyl-3-methylimidazolium bis[(trifluoromethyl)sulfonyl]imide ([C6mim][NTf2]). These measurements extend the ranges of our earlier study (Polikhronidi et al. in Phys Chem Liq 52:657, 2014) by 5 % of the compressed liquid density and by 75 K. An adiabatic calorimeter was used to measure one-phase (C_{V1}) liquid and two-phase (C_{V2}) liquid + vapor isochoric heat capacities, densities (ρ _s), and phase-transition temperatures (T_s) of the ionic liquid (IL) substance. The combined expanded uncertainty of the density ρ and isochoric heat capacity C_V measurements at the 95 % confidence level with a coverage factor of k = 2 is estimated to be 0.15 % and 3 %, respectively. Measurements are concentrated in the immediate vicinity of the liquid + vapor phase-transition curve, in order to closely observe phase transitions. The present measurements and those of our earlier study are analyzed together and are presented in terms of thermodynamic properties (T_s, ρ _s, C_{V1} and C_{V2}) evaluated at saturation and in terms of key-derived thermodynamic properties C_P, C_S, W_S^' }}, K_{TS}^' }}, ( {partial P/partial T} ) V^' }, and ( {partial V/partial T} ) _{P}^' }) on the liquid + vapor phase-transition curve. A thermodynamic relation by Yang and Yang is used to confirm the internal consistency of measured two-phase heat capacities C_{V2} , which are observed to fall perfectly on a line as a function of specific volume at a constant temperature. The observed linear behavior is exploited to evaluate contributions to the quantity C_{V2} = f(V, T) from chemical potential C_{{Vμ}} =-Td^{{2}}μ /dT2 and from vapor pressure C_{VP} =VTd2PS /dT2. The physical nature and specific details of the temperature and specific volume dependence of the two-phase isochoric heat capacity and some features of the other derived thermodynamic properties of IL at liquid saturation curve are considered

  6. Ionic association and solvation of the ionic liquid 1-hexyl-3-methylimidazolium chloride in molecular solvents revealed by vapor pressure osmometry, conductometry, volumetry, and acoustic measurements.

    PubMed

    Sadeghi, Rahmat; Ebrahimi, Nosaibah

    2011-11-17

    A systematic study of osmotic coefficient, conductivity, volumetric and acoustic properties of solutions of ionic liquid 1-hexyl-3-methylimidazolium chloride ([C(6)mim][Cl]) in various molecular solvents has been made at different temperatures in order to study of ionic association and solvation behavior of [C(6)mim][Cl] in different solutions. Precise measurements on electrical conductances of solutions of [C(6)mim][Cl] in water, methanol, ethanol, 1-propanol, 2-propanol, 1-butanol, and acetonitrile at 293.15, 298.15, and 303.15 K are reported and analyzed with Barthel's low-concentration chemical model (lcCM) to obtain the limiting molar conductivities and association constants of this ionic liquid in the investigated solvents. Strong ion pairing was found for the ionic liquid in 2-propanol, 1-butanol, and 1-propanol, whereas ion association in acetonitrile, methanol and ethanol is rather weak and in water the ionic liquid is fully dissociated. In the second part of this work, the apparent molar volumes and isentropic compressibilities of [C(6)mim][Cl] in water, methanol, ethanol, acetonitrile, 1-propanol, 2-propanol, and 1-butanol are obtained at the 288.15-313.15 K temperature range at 5 K intervals at atmospheric pressure from the precise measurements of density and sound velocity. The infinite dilution apparent molar volume and isentropic compressibility values of the free ions and ion pairs of [C(6)mim][Cl] in the investigated solvents as well as the excess molar volume of the investigated solutions are determined and their variations with temperature and type of solvents are also studied. Finally, the experimental measurements of osmotic coefficient at 318.15 K for binary solutions of [C(6)mim][Cl] in water, methanol, ethanol, 2-propanol, and acetonitrile are taken using the vapor pressure osmometry (VPO) method and from which the values of the solvent activity, vapor pressure, activity coefficients, and Gibbs free energies are calculated. The results are

  7. A new 1-hexyl-3-methylimidazolium tris(pentafluoroethyl)trifluorophosphate ionic liquid based ultrasound-assisted emulsification microextraction for the determination of organic ultraviolet filters in environmental water samples.

    PubMed

    Ge, Dandan; Lee, Hian Kee

    2012-08-17

    A novel microextraction approach termed ionic liquid based ultrasound-assisted emulsification microextraction (IL-USAEME) combined with high-performance liquid chromatography-ultraviolet (HPLC-UV) was developed for the preconcentration and detection of organic ultraviolet (UV) filters in environmental water samples. An ionic liquid (IL) was used in place of an organic solvent as in conventional USAEME. In the study, orthogonal array designs (OAD) were employed for the optimization of the extraction parameters: type of IL, pH of the sample, extraction volume, ultrasonic time and salt concentration. In the first step, a mixed level OAD matrix, OA(16) (4(1) × 2(12)) was employed for the initial optimization. Based on the results of the first step, an ultra-hydrophobic IL, 1-hexyl-3-methylimidazolium tris(pentafluoroethyl)trifluorophosphate was chosen as the IL extractant and sample pH was set at a value of 3. Ultrasonic time, extraction volume and salt concentration were further optimized in the second step by an OA(16) (4(5)) matrix. Under the latter optimized conditions, calibration curves with coefficients of estimation higher than 0.997 over the concentration range of 5 and 1000 ng/ml, and the relative standard deviations for six replicates of the extraction from 2.6 to 6.6% were obtained. The limits of detection for four organic UV filters were between 0.5 and 1 ng/ml. The validated technique was applied to the analysis of organic UV filters in environmental water samples.

  8. Dispersive liquid-liquid microextraction of pesticides and metabolites from soils using 1,3-dipentylimidazolium hexafluorophosphate ionic liquid as an alternative extraction solvent.

    PubMed

    Asensio-Ramos, María; Hernández-Borges, Javier; Ravelo-Pérez, Lidia M; Afonso, María M; Palenzuela, J Antonio; Rodríguez-Delgado, Miguel Ángel

    2012-05-01

    In this work, the use of the ionic liquid (IL) 1,3-dipentylimidazolium hexafluorophosphate ([PPIm][PF₆]) as an alternative extractant for IL dispersive liquid-liquid microextraction (IL-DLLME) of a group of pesticides and metabolites (2-aminobenzimidazole, carbendazim/benomyl, thiabendazole, fuberidazole, carbaryl, 1-naphthol, and triazophos) from soils is described. After performing an initial ultrasound-assisted extraction (USE), the IL-DLLME procedure was applied for the extraction of these organic analytes from soil extracts. Separation and quantification was achieved by high-performance liquid chromatography (HPLC) with fluorescence detection (FD). Calibration, precision, and accuracy of the described USE-IL-DLLME-HPLC-FD method using [PPIm][PF₆] as an alternative extractant was evaluated with two soils of different physicochemical properties. Accuracy percentages were in the range 93-118% with RSD values below 20%. A comparison of the performance of [PPIm][PF₆] versus that of the so-common 1-hexyl-3-methylimidazolium hexafluorophosphate ([HMIm][PF₆]) was accomplished. Results indicate a comparable extraction efficiency with both ILs, being slightly higher with [HMIm][PF₆] for the metabolite 2-aminobenzimidazole, and slightly higher with [PPIm][PF₆] for triazophos. In all cases, LODs were in the low ng/g range (0.02-14.2 ng/g for [HMIm][PF₆] and 0.02-60.5 ng/g for [PPIm][PF₆]). As a result, the current work constitutes a starting point for the use of the IL [PPIm][PF₆] for further analytical approaches.

  9. Electrophilic nitration of alkanes with nitronium hexafluorophosphate

    PubMed Central

    Olah, George A.; Ramaiah, Pichika; Prakash, G. K. Surya

    1997-01-01

    Nitration of alkanes such as methane, ethane, propane, n-butane, isobutane, neopentane, and cyclohexane was carried out with nitronium hexafluorophosphate in methylene chloride or nitroethane solution. Nitration of methane, albeit in poor yield, required protolytic activation of the nitronium ion. The results indicate direct electrophilic insertion of NO2+ into C 000000000000 000000000000 000000000000 000000000000 111111111111 000000000000 000000000000 000000000000 000000000000 H and CC σ-bonds. PMID:11038587

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

    PubMed

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

    2009-05-14

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

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

    NASA Astrophysics Data System (ADS)

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

    2009-05-01

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

  12. Application of thermogravimetric studies for optimization of lithium hexafluorophosphate production

    NASA Astrophysics Data System (ADS)

    Smagin, A. A.; Matyukha, V. A.; Korobtsev, V. P.

    Lithium hexafluorophosphate, isolated from hydrogen fluoride solution (anhydrous) by decanting and filtering, is an adduct of composition LiPF 6*HF. By thermogravimetric investigations the dynamics of HF removal from LiPF 6 by LiPF 6*HF thermal decomposition was studied. Based on the experimental data the constants entering into the equations as C = C0*exp( t*K0* exp(- E/RT)) were calculated, explaining the thermal decomposition processes of LiPF 6*HF and LiPF 6.

  13. Rapid determination of alkaloids in Macleaya cordata using ionic liquid extraction followed by multiple reaction monitoring UPLC-MS/MS analysis.

    PubMed

    Li, Linqiu; Huang, Mingyuan; Shao, Junli; Lin, Bokun; Shen, Qing

    2017-02-20

    The ultrasonic-assisted extraction (UAE) and ionic liquid based dispersive liquid-liquid microextraction (IL-DLLME) have been successfully applied in extracting of six alkaloids from M. cordata. 1-hexyl-3-methylimidazolium tetrafluoroborate ([C6MIM][BF4]) aqueous solution was used as extraction solvent. The target analytes in raw material were deposited into a single drop of 1-hexyl-3-methylimidazolium hexafluorophosphate ([C6MIM][PF6]), which was in situ formed by mixing [C6MIM][BF4] and potassium hexafluorophosphate ([K][PF6]. Afterwards, the extract was analyzed by ultra-performance liquid chromatography tandem mass spectrometry (UPLC-MS/MS) in multiple-reaction monitoring (MRM) mode. The proposed method was fully validated in terms of linearity (0.9983-0.9992), LOD (0.080ngmL(-1)), LOQ (0.25ngmL(-1)), intra-day precision (<5.46%), inter-day precision (<6.36%), and recovery (86.42-112.48%). The results indicate that the approach of combining IL-DLLME with UPLC-MS/MS is powerful and practical for analyzing alkaloids in M. cordata., and it also has great potential for comprehensive quality control of other herbal medicines.

  14. TX-100/water/1-butyl-3-methylimidazolium hexafluorophosphate microemulsions.

    PubMed

    Gao, Yanan; Han, Shuaibing; Han, Buxing; Li, Ganzuo; Shen, Dong; Li, Zhonghao; Du, Jimin; Hou, Wanguo; Zhang, Gaoyong

    2005-06-21

    Both ionic liquids and water are typical green solvents. In this work, the phase behavior of the ternary system consisting of ionic liquid 1-butyl-3-methylimidazolium hexafluorophosphate (bmimPF6), TX-100, and water was determined at 25.0 degrees C. The water-in-bmimPF6, bicontinuous, and bmimPF6-in-water microregions of the microemulsions were identified by cyclic voltammetry method using potassium ferrocyanide K4Fe(CN)6 as the electroactive probe. Dynamic light scattering (DLS) and the UV-vis method were used to characterize the microemulsions. It was demonstrated that the hydrodynamic diameter (Dh) of the bmimPF6-in-water microemulsions is nearly independent of the water content but increases with increasing bmimPF6 content due to the swelling of the micelles by the ionic liquid. The UV-vis further confirmed the existence of water domains in the water-in-bmimPF6 microemulsions, and the salt potassium ferricyanide K3Fe(CN)6 could be dissolved in the water domains.

  15. Thermal decomposition and vibrational spectroscopic aspects of pyridinium hexafluorophosphate (C5H5NHPF6)

    NASA Astrophysics Data System (ADS)

    Lekgoathi, M. D. S.; Kock, L. D.

    2016-12-01

    Thermal decomposition and vibrational spectroscopic properties of pyridinium hexafluorophosphate (C5H5NHPF6) have been studied. The structure of the compound is better interpreted as having a cubic space group, based on Raman and infrared vibrational spectroscopy experiments and group theoretical correlation data between site symmetry species and the spectroscopic space group. The 13C NMR data shows three significant signals corresponding to the three chemical environments expected on the pyridinium ring i.e. γ, β and α carbons, suggesting that the position of the anion must be symmetrical with respect to the pyridinium ring's C2v symmetry. The process of thermal decomposition of the compound using TGA methods was found to follow a contracting volume model. The activation energy associated with the thermal decomposition reaction of the compound is 108.5 kJ mol-1, while the pre exponential factor is 1.51 × 109 sec-1.

  16. Phase behavior and microstructure of microemulsions containing the hydrophobic ionic liquid 1-butyl-3-methylimidazolium hexafluorophosphate.

    PubMed

    Anjum, Nishat; Guedeau-Boudeville, Marie-Alice; Stubenrauch, Cosima; Mourchid, Ahmed

    2009-01-08

    The phase behavior and microstructure of the ternary system water/1-butyl-3-methylimidazolium hexafluorophosphate (bmimPF(6))/Triton X-100 was studied as a function of temperature and ionic liquid (IL) mass fraction alpha. In the present study, a hydrophobic IL instead of commonly used organic solvents such as n-alkanes is used. The fish-shaped region is distorted at low and high values of alpha, whereas it is symmetric at intermediate alpha. With increasing alpha, the extension of the three-phase region decreases regarding the surfactant concentration range, whereas it increases regarding the temperature range. For comparison the phase behavior of two ternary water/bmimPF(6)/alkyl oligoethyleneoxide (C(i)E(j)) systems has been investigated. Our results are compared with those obtained for water/n-alkane/C(i)E(j) and IL/n-alkane/C(i)E(j) systems, respectively.

  17. Synthesis of Bis(1,2-Dimethylimidazole)Copper(I)Hexafluorophosphate: An Experiment Using a Glove Box

    ERIC Educational Resources Information Center

    Niewahner, J. H.; Walters, Keith A.

    2007-01-01

    A detailed description of the synthesis of bis(1,2-dimethylimidazole)copper(I) hexafluorophosphate by using techniques in a glove box is presented. The results shows that the synthesis of the copper complex has a distinct color change indicating by-product oxidation by oxygen.

  18. Surfactant-free microemulsions of 1-butyl-3-methylimidazolium hexafluorophosphate, propylamine nitrate, and water.

    PubMed

    Xu, Jie; Deng, Huanhuan; Fu, Yunlei; Chen, Yuquan; Zhang, Jing; Hou, Wanguo

    2017-03-08

    Generally, surfactants (or amphiphiles) are believed to be necessary components of microemulsions. However, it has been demonstrated that, in the absence of traditional surfactants, microemulsions can also form from a ternary system of two immiscible fluids (i.e., oil and water phases) and an amphi-solvent, but the current understanding of such surfactant-free microemulsions (SFMEs) is very limited. Herein, we report an SFME consisting of the hydrophobic ionic liquid (IL) 1-butyl-3-methylimidazolium hexafluorophosphate (bmimPF6), the protic IL propylamine nitrate (PAN), and water, in which bmimPF6 and PAN are used as the oil phase and the amphi-solvent, respectively. The microstructures and structural transitions of the SFME were investigated using cyclic voltammetry, fluorescence spectroscopy, and ultraviolet-visible spectroscopy. The SFME exhibited water-in-bmimPF6 (W/IL), bicontinuous (BC), and bmimPF6-in-water (IL/W) microstructures, depending on the composition of the ternary system, similar to the case of traditional surfactant-based microemulsions (SBMEs). The three kinds of microstructures were confirmed by cryogenic transmission electron microscopy (cryo-TEM) observations. To the best of our knowledge, this is the first report on SFMEs composed of two ILs as components, especially where one is used as the amphi-solvent.

  19. Electrochemically-Induced Reactions of Hexafluorophosphate Anions with Water in Negative Ion Electrospray Mass Spectrometry of Undiluted Ionic Liquids

    SciTech Connect

    Lu, Yuchen; Duckworth, Douglas {Doug} C; King, Fred L

    2006-01-01

    The influence of water on the observed gas-phase population of negative ions in electrospray mass spectrometry was studied for the undiluted ionic liquid 1,3-butyl-methyl-imidazolium hexafluorophosphate (BMIMPF6 ). During the electrospray process, electrolytic reduction of water enhances the production of tetrafluorophosphate (F4PO), which undergoes further reactions to produce difluorophosphate (F2PO2 ) anions. These anions are observed in addition to the pre-existing hexafluorophosphate anion. The apparent substitution of two fluorine atoms with one oxygen is attributed to a series of reactions initiated by hydrolysis of hexafluorophosphate. This hydrolysis reaction was enhanced by the addition of hydroxide, formed via the hydrolysis of water or through the addition of ammonium hydroxide. The formation of FxPOy was studied as a function of the electrospray current and solution flow rate. The mass spectral response shows a quantitative logarithmic relationship between FxPOy signal intensities (adjusted for mole equivalents of H2O required) and the amount of water present, against which the water content could be rapidly assessed. Results were found to be comparable to Karl Fischer titration data

  20. Solid state vibrational spectroscopy of anhydrous lithium hexafluorophosphate (LiPF6)

    NASA Astrophysics Data System (ADS)

    Kock, L. D.; Lekgoathi, M. D. S.; Crouse, P. L.; Vilakazi, B. M.

    2012-10-01

    Raman and infrared studies of solid anhydrous lithium hexafluorophosphate (LiPF6) have been carried out. The studies were complemented by X-ray powder diffraction (XRD) and Thermogravimetric (TG) analysis techniques. The results indicate that when solid LiPF6 is studied in a strictly anhydrous environment, more consistent thermal stability data can be obtained. TG analysis, using a scan rate of 10 °C min-1, indicate the onset of thermal decomposition of the anhydrous LiPF6 occurring at about 134.84 °C while the partially hydrolysed compound starts at 114.46 °C. The Raman spectra of anhydrous MPF6 (M = Li+, Na+ and K+) are best interpreted in terms of a cubic space group Fm3m(Ohs), (ZB = 1), giving rise to 21 vibrational modes (A1g(R)+Eg(R)+T1g+T2g(R)+3T1u(1R)+T2u) and as such, LiPF6 may be considered isostructural with NaPF6 and KPF6. Crystal symmetry distortions in the anhydrous LiPF6 give rise additional bands in the Raman spectrum due to T1u infrared active modes and the ν1 (A1g) Raman band appears in the infrared spectrum in violation of the mutual exclusion selection rule for centro-symmetric sites. When these observations are considered, the Raman spectrum of LiPF6 is similar to those of NaPF6 and KPF6, with observations of the expected shifts due to cation size and/or electronegativity effects.

  1. Photoisomerization of cyanine derivatives in 1-butyl-3-methylimidazolium hexafluorophosphate and aqueous glycerol: Influence of specific interactions

    SciTech Connect

    Mali, K. S.; Dutt, G. B.; Mukherjee, T.

    2008-03-28

    Photoisomerization of two cyanine derivatives, 3,3{sup '}-diethyloxadicarbocyanine iodide (DODCI) and merocyanine 540 (MC 540), has been investigated in an ionic liquid, 1-butyl-3-methylimidazolium hexafluorophosphate and aqueous glycerol (93 wt % glycerol +7 wt % water) by measuring fluorescence lifetimes and quantum yields. The aim of this work is to understand how the rates of photoisomerization of DODCI and MC 540 are influenced by specific solute-solvent interactions besides the viscosity of the medium. For DODCI, it has been observed that the nonradiative rate constants, which represent the rates of photoisomerization, are almost identical in the ionic liquid and aqueous glycerol at given temperature, indicating that viscosity is the sole parameter that governs the rate of photoisomerization. In contrast, the photoisomerization rate constants of MC 540 have been found to be a factor of 2 higher in aqueous glycerol compared to the ionic liquid. The observed behavior is due to the zwitterionic character of MC 540, a consequence of which, the twisted state gets stabilized by the solute-solvent hydrogen bonding interactions in aqueous glycerol, thus lowering the barrier for isomerization.

  2. Dispersive liquid-liquid microextraction of silver nanoparticles in water using ionic liquid 1-octyl-3-methylimidazolium hexafluorophosphate.

    PubMed

    Chen, Sha; Sun, Yuanjing; Chao, Jingbo; Cheng, Liping; Chen, Yun; Liu, Jingfu

    2016-03-01

    Using the ionic liquid (IL) 1-octyl-3-methylimidazolium hexafluorophosphate as the extractant and methanol as the dispersion solvent, a dispersive liquid-liquid microextraction method was developed to extract silver nanoparticles (AgNPs) from environmental water samples. Parameters that influenced the extraction efficiency such as IL concentration, pH and extraction time were optimized. Under the optimized conditions, the highest extraction efficiency for AgNPs was above 90% with an enrichment factor of >90. The extracted AgNPs in the IL phase were identified by transmission electron microscopy and ultraviolet-visible spectroscopy, and quantified by inductively coupled plasma mass spectrometry after microwave digestion, with a detection limit of 0.01μg/L. The spiked recovery of AgNPs was 84.4% with a relative standard deviation (RSD) of 3.8% (n=6) at a spiked level of 5μg/L, and 89.7% with a RSD of 2.2% (n=6) at a spiked level of 300μg/L, respectively. Commonly existed environmental ions had a very limited influence on the extraction efficiency. The developed method was successfully applied to the analysis of AgNPs in river water, lake water, and the influent and effluent of a wastewater treatment plant, with recoveries in the range of 71.0%-90.9% at spiking levels of 0.11-4.7μg/L.

  3. Temperature-controlled ionic liquid dispersive liquid-phase microextraction for the sensitive determination of triclosan and triclocarban in environmental water samples prior to HPLC-ESI-MS/MS.

    PubMed

    Zhao, Ru-Song; Wang, Xia; Sun, Jing; Yuan, Jin-Peng; Wang, Shan-Shan; Wang, Xi-Kui

    2010-06-01

    A novel dispersive liquid-phase microextraction method without dispersive solvents has been developed for the enrichment and sensitive determination of triclosan and triclocarban in environmental water samples prior to HPLC-ESI-MS/MS. This method used only green solvent 1-hexyl-3-methylimidazolium hexafluorophosphate as extraction solvent and overcame the demerits of the use of toxic solvents and the instability of the suspending drop in single drop liquid-phase microextraction. Important factors that may influence the enrichment efficiencies, such as volume of ionic liquid, pH of solutions, extraction time, centrifuging time and temperature, were systematically investigated and optimized. Under optimum conditions, linearity of the method was observed in the range of 0.1-20 microg/L for triclocarban and 0.5-100 microg/L for triclosan, respectively, with adequate correlation coefficients (R>0.9990). The proposed method has been found to have excellent detection sensitivity with LODs of 0.04 and 0.3 microg/L, and precisions of 4.7 and 6.0% (RSDs, n=5) for triclocarban and triclosan, respectively. This method has been successfully applied to analyze real water samples and satisfactory results were achieved.

  4. Double dispersant-assisted ionic liquid dispersive liquid-liquid microextraction coupled with capillary electrophoresis for the determination of benzophenone-type ultraviolet filters in sunscreen cosmetic product.

    PubMed

    Ma, Teng; Li, Zheng; Niu, Qian; Li, Yuanyuan; Zhou, Weihong

    2015-10-01

    In this work, double dispersant-assisted ionic liquid dispersive liquid-liquid microextraction coupled with micellar electrokinetic chromatography was developed to determine four UV filters (benzophenone, 4-hydroxybenzophenone, 2,4-dihydroxybenzophenone, and 2-hydroxy-4-methoxybenzophenone). 1-Hexyl-3-methylimidazolium hexafluorophosphate was used as the extraction solvent. The main novelty of the present work was that acetonitrile-Triton X-114 was used as double disperser solvent. Parameters affected the extraction efficiency were investigated and optimized. Under the optimum conditions, enrichment factors were in the range of 25.3-40.5. The limits of detection and quantitation, calculated at a S/N of three and ten, were 3.9-6.7 ng/mL and 13.0-22.3 ng/mL. The linearity of the method was in the range of 0.02-2 μg/mL for 2, 4-dihydroxybenzophenone and 4-hydroxybenzophenone, 0.01-2 μg/mL for benzophenone and 2-hydroxy-4-methoxybenzophenone, with correlation coefficient (R(2)) of 0.9984-0.9991. The proposed method was successfully applied to the determination of four benzophenone-type UV filters in six kinds of sunscreen cosmetic products, with yielded relative recoveries ranging from 80.2 to 117.7%.

  5. Recombination of Photogenerated Lophyl Radicals in Imidazolium-Based Ionic Liquids

    SciTech Connect

    Strehmel, V.; Wishart, J.; Polyansky, D.E.; Strehmel, B.

    2009-10-20

    Laser flash photolysis is applied to study the recombination reaction of lophyl radicals in ionic liquids in comparison with dimethylsulfoxide as an example of a traditional organic solvent. The latter exhibits a similar micropolarity as the ionic liquids. The ionic liquids investigated are 1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide (1), 1-hexyl-3-methylimidazolium hexafluorophosphate (2), and 1-butyl-3-methylimidazolium tetafluoroborate (3). The recombination of the photolytic generated lophyl radicals occur significantly faster in the ionic liquids than expected from their macroscopic viscosities and is a specific effect of these ionic liquids. On the other hand, this reaction can be compared with the macroscopic viscosity in the case of dimethylsulfoxide. Activation parameters obtained for lophyl radical recombination suggest different, anion-dependent mechanistic effects. Quantum chemical calculations based on density functional theory provide a deeper insight of the molecular properties of the lophyl radical and its precursor. Thus, excitation energies, spin densities, molar volumes, and partial charges are calculated. Calculations show a spread of spin density over the three carbon atoms of the imidazolyl moiety, while only low spin density is calculated for the nitrogens.

  6. Combination of ultrasound-assisted ionic liquid dispersive liquid-phase microextraction and high performance liquid chromatography for the sensitive determination of benzoylureas pesticides in environmental water samples.

    PubMed

    Zhou, Qingxiang; Zhang, Xiaoguo

    2010-12-01

    This paper describes a new method for rapid and sensitive determination of diflubenzuron, flufenoxuron, triflumuron and chlorfluazuron in water samples by ultrasound-assisted ionic liquid dispersive liquid-phase microextraction in combination with HPLC. Ionic liquid 1-hexyl-3-methylimidazolium hexafluorophosphate ([C(6)MIM][PF(6)]) was used as the extraction solvent for the enrichment of four benzoylurea (BU) pesticides. Factors such as volume of [C(6)MIM][PF(6)], sonication time, sample pH, extraction time, centrifuging time and salting-out effect were systematically investigated. Under the optimum conditions, an excellent linear relationship was achieved in the range of 1.0-100 μg/L. The detection limits varied from 0.21 to 0.45 μg/L and the precision of the method was below 6.9% (RSD, n=6). The proposed method was successfully applied for the determination of these BU pesticides in water samples and excellent spiked recoveries were achieved. All these results demonstrated that this procedure provided a new simple, rapid, easy to operate, efficient and sensitive method for the analysis of BU pesticides in aqueous samples.

  7. Chromium speciation in human blood samples based on acetyl cysteine by dispersive liquid-liquid biomicroextraction and in-vitro evaluation of acetyl cysteine/cysteine for decreasing of hexavalent chromium concentration.

    PubMed

    Shirkhanloo, Hamid; Ghazaghi, Mehri; Mousavi, Hassan Z

    2016-01-25

    A rapid and efficient method based on ionic liquid dispersive liquid-liquid biomicroextraction (IL-DLLBME) was used for speciation and preconcentration of Chromium (III, VI) in human blood samples before determination by electro-thermal atomic absorption spectrometer (ET-AAS). In this method, 1-hexyl-3-methylimidazolium hexafluorophosphate as a ionic liquid was dissolved in acetone as a dispersant solvent and then the binary solution was rapidly injected by a syringe into the blood samples containing Cr(III), which have already complexed by acetyl cysteine (NAC) at optimized pH. Under the optimal conditions, the linear range (LR), limit of detection (LOD) and preconcentration factor (PF) were obtained 0.03-4.4 μg L(-1), 0.005 μg L(-1) and 10 respectively (RSD <5%). In vitro study show us, the cysteine (Cys) as a prodrug of NAC can decrease the concentration of Cr(VI) in blood samples and human body. Validation of methodology was confirmed by standard reference material (SRM).

  8. Speciation analysis of mercury in sediments using ionic-liquid-based vortex-assisted liquid-liquid microextraction combined with high-performance liquid chromatography and cold vapor atomic fluorescence spectrometry.

    PubMed

    Leng, Geng; Chen, Wenjin; Wang, Yong

    2015-08-01

    An improved novel method based on ionic liquid vortex-assisted liquid-liquid microextraction has been developed for the extraction of methylmercury, ethylmercury and inorganic mercury in sediment samples prior to analysis by high-performance liquid chromatography with cold vapor atomic fluorescence spectrometry. In this work, mercury species were firstly complexed with dithizone, and the complexes were extracted into 1-hexyl-3-methylimidazolium hexafluorophosphate. Key factors that affect the extraction efficiency of mercury species, such as type and amount of ionic liquid and chelatants, extraction time, sample pH, salt effect and matrix effect were investigated. Under the optimum conditions, linearity was found in the concentration range from 0.1-70 ng/g. Limits of detection ranged from 0.037-0.061 ng/g. Reproducibility and recoveries were assessed by extracting a series of six independent sediment samples that were spiked with different concentration levels. Finally, the proposed method was successfully applied in analysis of real sediment samples. In this work, ionic liquids vortex-assisted liquid-liquid microextraction was for the first time used for the extraction of mercury species in sediment samples. The proposed method was proved to be much simpler and more rapid, as well as more environmentally friendly and efficient compared with the previous methods.

  9. Ionic-liquid-based surfactant-emulsified microextraction procedure accelerated by ultrasound radiation followed by high-performance liquid chromatography for the simultaneous determination of antidepressant and antipsychotic drugs.

    PubMed

    Zare, Fahimeh; Ghaedi, Mehrorang; Daneshfar, Ali

    2015-03-01

    In the present work, an efficient and environmental friendly method of ionic-liquid-based emulsified microextraction procedure accelerated by ultrasound radiation has been developed. Subsequently, its performance was compared with dispersive liquid-liquid microextraction and ultrasound-assisted surfactant-based emulsification microextraction methods. The optimization of experimental conditions was carried out by combination of central composite design and response surface methodology. The optimum conditions of variables were set as follows: 50 μL of 1-hexyl-3-methylimidazolium hexafluorophosphate (extracting solvent), 10 min ultrasound time, and 10 min vortex time for agitating 6 mL sample solution in pH 3 in the presence of 4 mg sodium dodecyl sulfate without addition of salt and 200 μL of methanol as diluent solvent. Under these conditions, the responses are linear for doxepin and perphenazine in the range of 0.3-1000 and 5-1000 μg/L, respectively. The limits of detection were 0.1 μg/L for doxepin and 1 μg/L for perphenazine. Relative standard deviations were lower than 3.5 for the determination of both species. Finally, the method was used for the preconcentration and determination of doxepin and perphenazine in urine sample with relative recoveries in the range of 89-98%.

  10. Vortex-assisted ionic liquid dispersive liquid-liquid microextraction for the determination of sulfonylurea herbicides in wine samples by capillary high-performance liquid chromatography.

    PubMed

    Gure, Abera; Lara, Francisco J; García-Campaña, Ana M; Megersa, Negussie; del Olmo-Iruela, Monsalud

    2015-03-01

    A new sample treatment, namely vortex-assisted ionic liquid dispersive liquid-liquid microextraction (VA-IL-DLLME), followed by capillary liquid chromatography has been developed for the determination of four sulfonylurea herbicides (SUHs): flazasulfuron (FS), prosulfuron (PS), primisulfuron-methyl (PSM) and triflusulfuron-methyl (TSM) in wine samples. The ionic liquid (IL) 1-hexyl-3-methylimidazolium hexafluorophosphate ([C6MIM][PF6]) was used as extraction solvent and was dispersed using methanol into the sample solution, assisted by a vortex mixer. Various parameters influencing the extraction efficiency, such as type and amount of IL, type and volume of disperser solvent, sample pH, salting-out effect, vortex and centrifugation time were studied. Under the optimum conditions, the limits of detection and quantification of the proposed method were in the ranges of 3.2-6.6 and 10.8-22.0 μg kg(-1), respectively; lower than the maximum residue limits set by the EU for these matrices. The proposed method was successfully applied to different wine samples and satisfactory recoveries were obtained.

  11. Binary-solvent-based ionic-liquid-assisted surfactant-enhanced emulsification microextraction for the determination of four fungicides in apple juice and apple vinegar.

    PubMed

    Chen, Xiaochu; Zhang, Xu; Liu, Fengmao; Hou, Fan

    2017-02-01

    A binary-solvent-based ionic-liquid-assisted surfactant-enhanced emulsification microextraction method was developed for the separation/preconcentration and determination of four fungicides (pyrimethanil, fludioxonil, cyprodynil, pyraclostrobin) in apple juice and apple vinegar. A nonchlorinated solvent amyl acetate, which has a lower density than water, was used as the extraction solvent, and an ionic liquid 1-hexyl-3-methylimidazolium hexafluorophosphate, which has a high density and low toxicity, was used as a secondary solvent mixed with the extraction solvent. After centrifugation, the binary solvent drop with a relatively high density was deposited on the bottom of the tube. Some parameters influencing the extraction efficiency of analytes such as type of extraction solvent, ratio of ionic liquid, volume of mixed solvent, type and concentration of surfactant, sample pH, NaCl concentration, and vortex time were investigated and optimized. Under the optimized conditions, the proposed method provided a good linearity in the range of 5-200 μg/L. The limits of quantification of the method were in the range of 2-5 μg/L. The relative standard deviations for interday assays were 1.7-11.9%. The method was applied to the determination of pyrimethanil, fludioxonil, cyprodynil, and pyraclostrobin in apple juice and apple vinegar samples, and the accuracy was evaluated through recovery experiments.

  12. Determination of diflubenzuron and chlorbenzuron in fruits by combining acetonitrile-based extraction with dispersive liquid-liquid microextraction followed by high-performance liquid chromatography.

    PubMed

    Ruan, Chunqiang; Zhao, Xiang; Liu, Chenglan

    2015-09-01

    In this study, a simple and low-organic-solvent-consuming method combining an acetonitrile-partitioning extraction procedure followed by "quick, easy, cheap, effective, rugged and safe" cleanup with ionic-liquid-based dispersive liquid-liquid microextraction and high-performance liquid chromatography with diode array detection was developed for the determination of diflubenzuron and chlorbenzuron in grapes and pears. Ionic-liquid-based dispersive liquid-liquid microextraction was performed using the ionic liquid 1-hexyl-3-methylimidazolium hexafluorophosphate as the extractive solvent and acetonitrile extract as the dispersive solvent. The main factors influencing the efficiency of the dispersive liquid-liquid microextraction were evaluated, including the extractive solvent type and volume and the dispersive solvent volume. The validation parameters indicated the suitability of the method for routine analyses of benzoylurea insecticides in a large number of samples. The relative recoveries at three spiked levels ranged between 98.6 and 109.3% with relative standard deviations of less than 5.2%. The limit of detection was 0.005 mg/kg for the two insecticides. The proposed method was successfully used for the rapid determination of diflubenzuron and chlorbenzuron residues in real fruit samples.

  13. Salting-out homogenous extraction followed by ionic liquid/ionic liquid liquid-liquid micro-extraction for determination of sulfonamides in blood by high performance liquid chromatography.

    PubMed

    Liu, Zhongling; Yu, Wei; Zhang, Hanqi; Gu, Fanbin; Jin, Xiangqun

    2016-12-01

    Salting-out homogenous extraction followed by ionic liquid/ionic liquid dispersive liquid-liquid micro-extraction system was developed and applied to the extraction of sulfonamides in blood. High-performance liquid chromatography was applied to the determination of the analytes. The blood sample was centrifuged to obtain the serum. After the proteins in the serum were removed in the presence of acetonitrile, ionic liquid 1-butyl-3-methylimidazolium tetrafluoroborate, dipotassium hydrogen phosphate, ionic liquid 1-Hexyl-3-methylimidazolium hexafluorophosphate were added into the resulting solution. After the resulting mixture was ultrasonically shaken and centrifuged, the precipitate was separated. The acetonitrile was added in the precipitate and the analytes were extracted into the acetonitrile phase. The parameters affecting the extraction efficiency, such as volume of ionic liquid, amount of dipotassium hydrogen phosphate, volume of dispersant, extraction time and temperature were investigated. The limits of detection of sulfamethizole (STZ), sulfachlorpyridazine (SCP), sulfamethoxazole (SMX) and Sulfisoxazole (SSZ) were 4.78, 3.99, 5.21 and 3.77μgL(-1), respectively. When the present method was applied to the analysis of real blood samples, the recoveries of analytes ranged from 90.0% to 113.0% and relative standard deviations were lower than 7.2%.

  14. Ultrasound-assisted ionic liquid-based microextraction combined with least squares support vector machines regression for the simultaneous determination of aluminum, gallium, and indium in water and coal samples.

    PubMed

    Ghasemi, Jahan B; Zolfonoun, Ehsan

    2012-06-01

    A new simple and rapid ultrasound-assisted ionic liquid-based microextraction method was applied to preconcentrate aluminum(III), gallium(III), and indium(III) ions from water samples as a prior step to their simultaneous spectrophotometric determination using least squares support vector machines regression. In the novel procedure, 1-hexyl-3-methylimidazolium hexafluorophosphate [C(6)MIM][PF(6)] was dispersed into the aqueous sample solution as fine droplets by ultrasonication, and the analytes were extracted into the ionic liquid phase after complexation with 1,2,5,8-tetrahydroxy anthraquinone (quinalizarine). After centrifuging, the fine droplets of extractant phase were settled to the bottom of the conical-bottom glass centrifuge tube. The detection limits for Al(III), Ga(III), and In(III) were 1.70, 2.02, and 2.06 ng mL(-1), respectively. The precision of the method, evaluated as the relative standard deviation obtained by analyzing a series of ten replicates, was below 3.2% for all elements. The method was successfully applied for the determination of Al(III), Ga(III), and In(III) in real samples.

  15. A novel electrochemical aptasensor for ultrasensitive detection of kanamycin based on MWCNTs-HMIMPF6 and nanoporous PtTi alloy.

    PubMed

    Guo, Wenjuan; Sun, Na; Qin, Xiaoli; Pei, Meishan; Wang, Luyan

    2015-12-15

    A novel aptasensor based on a novel composite film consisting of multi-walled carbon nanotubes (MWCNTs), ionic liquid (IL) of 1-hexyl-3-methylimidazolium hexafluorophosphate (HMIMPF6), and nanoporous PtTi (NP-PtTi) alloy was constructed for ultrasensitive detection of kanamycin. The NP-PtTi alloy was successfully fabricated by a simple dealloying of PtTiAl source alloy in HCl solution. The NP-PtTi alloy has uniform interconnected network structure with specific surface area and was used to immobilize aptamer. After modified with the composite material, current signal was amplified obviously, which attributed to the larger specific surface area and excellent electrical conductivity of NP-PtTi and MWCNTs. A number of factors affecting the activity of the aptasensor have been discussed and optimized. Under the optimized conditions, the proposed aptasensor provided a linear range of 0.05-100 ng mL(-1) with a low detection limit of 3.7 pg mL(-1). This aptasensor displayed high sensitivity, stability and reproducibility. In addition, the as-prepared aptasensor was successfully used for the determination of kanamycin in a real sample.

  16. Ionic liquids influence on the surface properties of electron beam irradiated wood

    NASA Astrophysics Data System (ADS)

    Croitoru, Catalin; Patachia, Silvia; Doroftei, Florica; Parparita, Elena; Vasile, Cornelia

    2014-09-01

    In this paper, the influence of three imidazolium-based ionic liquids (1-butyl-3-methylimidazolium tetrafluoroborate, 1-butyl-3-methylimidazolium hexafluorophosphate and 1-hexyl-3-methylimidazolium chloride) on the structure and surface properties of sycamore maple (Acer pseudoplatanus) veneers submitted to electron beam irradiation with a dose of 50 kGy has been studied by using Fourier transform infrared spectroscopy, as well as image, scanning electron microscopy/SEM/EDX, atomic force microscopy and contact angle analysis. The experimental results have proven that the studied ionic liquids determine a better preservation of the structural features of wood (cellulose crystallinity index and lignin concentration on the surface) as well as some of surface properties such as surface energy, roughness, color upon irradiation with electron beam, in comparison with the reference wood, but surface composition is changed by treatment with imidazolium-based ionic liquids mainly with 1-butyl-3-methylimidazolium tetrafluoroborate. Also, under electron beam irradiation covalent bonding of the imidazolium moiety to wood determines a higher resistance to water penetration and spreading on the surface.

  17. Quantitative analysis of piroxicam using temperature-controlled ionic liquid dispersive liquid phase microextraction followed by stopped-flow injection spectrofluorimetry

    PubMed Central

    2013-01-01

    Background Piroxicam (PXM) belongs to the wide class of non-steroidal anti-inflammatory drugs (NSAIDs). PXM has been widely applied in the treatment of rheumatoid arthritis, gonarthrosis, osteoarthritis, backaches, neuralgia, mialgia. In the presented work, a green and benign sample pretreatment method called temperature-controlled ionic liquid dispersive liquid phase microextraction (TCIL-DLPME) was followed with stopped-flow injection spectrofluorimetry (SFIS) for quantitation of PXM in pharmaceutical formulations and biological samples. Methods Temperature-controlled ionic liquid dispersive liquid phase microextraction (TCIL-DLPME) was applied as an environmentally friendly sample enrichment method to extract and isolate PXM prior to quantitation. Dispersion of 1-hexyl-3-methylimidazolium hexafluorophosphate ([Hmim][PF6]) ionic liquid (IL) through the sample aqueous solution was performed by applying a relatively high temperature. PXM was extracted into the extractor, and after phase separation, PXM in the final solution was determined by stopped-flow injection spectrofluorimetry (SFIS). Results and Major Conclusion Different factors affecting the designed method such as IL amount, diluting agent, pH and temperature were investigated in details and optimized. The method provided a linear dynamic range of 0.2-150 μg l-1, a limit of detection (LOD) of 0.046 μg l-1 and a relative standard deviation (RSD) of 3.1%. Furthermore, in order to demonstrate the analytical applicability of the recommended method, it was applied for quantitation of PXM in real samples. PMID:23895461

  18. Surface structures of equimolar mixtures of imidazolium-based ionic liquids using high-resolution Rutherford backscattering spectroscopy

    NASA Astrophysics Data System (ADS)

    Nakajima, Kaoru; Oshima, Shinichi; Suzuki, Motofumi; Kimura, Kenji

    2012-11-01

    Surface structures of equimolar mixtures of imidazolium-based ionic liquids (ILs) having a common cation (1-butyl-3-methylimidazolium ([C4MIM]) or 1-hexyl-3-methylimidazolium ([C6MIM])) and different anions (bis(trifluoromethanesulfonyl)imide ([TFSI]), hexafluorophosphate ([PF6]) or chlorine) are studied using high-resolution Rutherford backscattering spectroscopy (HRBS). Both cations and anions have the same preferential orientations at the surface as in the pure ILs. In the mixture, the larger anion is located shallower than the smaller anion. The [TFSI] anion is slightly enriched at the surface relative to [PF6] with coverage of ~ 60% for the equimolar mixtures of [C4(6)MIM] [TFSI] and [C4(6)MIM] [PF6]. No surface segregation is observed for [C6MIM] [TFSI]0.5[Cl]0.5 and [C6MIM] [PF6]0.5[Cl]0.5. These results are different from the recent TOF-SIMS measurement where very strong surface segregation of [TFSI] was concluded for the mixture of [C4MIM] [TFSI] and [C4MIM] [PF6].

  19. Ionic liquid-impregnated agarose film two-phase micro-electrodriven membrane extraction (IL-AF-μ-EME) for the analysis of antidepressants in water samples.

    PubMed

    Mohamad Hanapi, Nor Suhaila; Sanagi, Mohd Marsin; Ismail, Abd Khamim; Wan Ibrahim, Wan Aini; Saim, Nor'ashikin; Wan Ibrahim, Wan Nazihah

    2017-03-01

    The aim of this study was to investigate and apply supported ionic liquid membrane (SILM) in two-phase micro-electrodriven membrane extraction combined with high performance liquid chromatography-ultraviolet detection (HPLC-UV) for pre-concentration and determination of three selected antidepressant drugs in water samples. A thin agarose film impregnated with 1-hexyl-3-methylimidazolium hexafluorophosphate, [C6MIM] [PF6], was prepared and used as supported ionic liquid membrane between aqueous sample solution and acceptor phase for extraction of imipramine, amitriptyline and chlorpromazine. Under the optimized extraction conditions, the method provided good linearity in the range of 1.0-1000μgL(-1), good coefficients of determination (r(2)=0.9974-0.9992) and low limits of detection (0.1-0.4μgL(-1)). The method showed high enrichment factors in the range of 110-150 and high relative recoveries in the range of 88.2-111.4% and 90.9-107.0%, for river water and tap water samples, respectively with RSDs of ≤7.6 (n=3). This method was successfully applied to the determination of the drugs in river and tap water samples. It is envisaged that the SILM improved the perm-selectivity by providing a pathway for targeted analytes which resulted in rapid extraction with high degree of selectivity and high enrichment factor.

  20. Ionic-liquid-impregnated resin for the microwave-assisted solid-liquid extraction of triazine herbicides in honey.

    PubMed

    Wu, Lijie; Song, Ying; Hu, Mingzhu; Yu, Cui; Zhang, Hanqi; Yu, Aimin; Ma, Qiang; Wang, Ziming

    2015-09-01

    Microwave-assisted ionic-liquid-impregnated resin solid-liquid extraction was developed for the extraction of triazine herbicides, including cyanazine, metribuzin, desmetryn, secbumeton, terbumeton, terbuthylazine, dimethametryn, and dipropetryn in honey samples. The ionic-liquid-impregnated resin was prepared by immobilizing 1-hexyl-3-methylimidazolium hexafluorophosphate in the microspores of resin. The resin was used as the extraction adsorbent. The extraction and enrichment of analytes were performed in a single step. The extraction time can be shortened greatly with the help of microwave. The effects of experimental parameters including type of resin, type of ionic liquid, mass ratio of resin to ionic liquid, extraction time, amount of the impregnated resin, extraction temperature, salt concentration, and desorption conditions on the extraction efficiency, were investigated. A Box-Behnken design was applied to the selection of the experimental parameters. The recoveries were in the range of 80.1 to 103.4% and the relative standard deviations were lower than 6.8%. The present method was applied to the analysis of honey samples.

  1. Separation and preconcentration system based on ultrasonic probe-assisted ionic liquid dispersive liquid-liquid microextraction for determination trace amount of chromium(VI) by electrothermal atomic absorption spectrometry.

    PubMed

    Chen, Hao; Du, Ping; Chen, Jie; Hu, Shenghua; Li, Shengqing; Liu, Hanlan

    2010-04-15

    A novel method of ultrasonic probe-assisted ionic liquid dispersive liquid-liquid microextraction combined with electrothermal atomic absorption spectrometry (ETAAS) was developed for the determination of chromium(VI) species in water samples. In this procedure, the hydrophobic chelate of chromium(VI) with ammonium pyrrolidinedithiocarbamate (APDC) was extracted into the fine droplets of 1-hexyl-3-methylimidazolium hexafluorophosphate ([Hmim][PF(6)]), which was dispersed into the aqueous sample solution by ultrasonication using an ultrasonic probe. Several variables such as the volume of [Hmim][PF(6)], sample pH, concentration of APDC, and extraction time were investigated in detail. Under the optimum conditions, the limit of detection of the proposed method was 0.07 ng mL(-1) for Cr(VI) and the relative standard deviation for five-replicated determination of 2.0 ng mL(-1) Cr(VI) was 9.2%. The proposed method has been also successfully applied to the determination of chromium(VI) species in lake and tap water samples.

  2. Ionic-liquid-based hollow-fiber liquid-phase microextraction method combined with hybrid artificial neural network-genetic algorithm for speciation and optimized determination of ferro and ferric in environmental water samples.

    PubMed

    Saeidi, Iman; Barfi, Behruz; Asghari, Alireza; Gharahbagh, Abdorreza Alavi; Barfi, Azadeh; Peyrovi, Moazameh; Afsharzadeh, Maryam; Hojatinasab, Mostafa

    2015-10-01

    A novel and environmentally friendly ionic-liquid-based hollow-fiber liquid-phase microextraction method combined with a hybrid artificial neural network (ANN)-genetic algorithm (GA) strategy was developed for ferro and ferric ions speciation as model analytes. Different parameters such as type and volume of extraction solvent, amounts of chelating agent, volume and pH of sample, ionic strength, stirring rate, and extraction time were investigated. Much more effective parameters were firstly examined based on one-variable-at-a-time design, and obtained results were used to construct an independent model for each parameter. The models were then applied to achieve the best and minimum numbers of candidate points as inputs for the ANN process. The maximum extraction efficiencies were achieved after 9 min using 22.0 μL of 1-hexyl-3-methylimidazolium hexafluorophosphate ([C6MIM][PF6]) as the acceptor phase and 10 mL of sample at pH = 7.0 containing 64.0 μg L(-1) of benzohydroxamic acid (BHA) as the complexing agent, after the GA process. Once optimized, analytical performance of the method was studied in terms of linearity (1.3-316 μg L(-1), R (2) = 0.999), accuracy (recovery = 90.1-92.3%), and precision (relative standard deviation (RSD) <3.1). Finally, the method was successfully applied to speciate the iron species in the environmental and wastewater samples.

  3. Nanofluid of zinc oxide nanoparticles in ionic liquid for single drop liquid microextraction of fungicides in environmental waters prior to high performance liquid chromatographic analysis.

    PubMed

    Amde, Meseret; Tan, Zhi-Qiang; Liu, Rui; Liu, Jing-Fu

    2015-05-22

    Using a nanofluid obtained by dispersing ZnO nanoparticles (ZnO NPs) in 1-hexyl-3-methylimidazolium hexafluorophosphate, new single drop microextraction method was developed for simultaneous extraction of three fungicides (chlorothalonil, kresoxim-methyl and famoxadone) in water samples prior to their analysis by high performance liquid chromatography (HPLC-VWD). The parameters affecting the extraction efficiency such as amount of ZnO NPs in the nanofluid, solvent volume, extraction time, stirring rate, pH and ionic strength of the sample solution were optimized. Under the optimized conditions, the limits of detection were in the range of 0.13-0.19ng/mL, the precision of the method assessed with intra-day and inter-day relative standard deviations were <4.82% and <7.04%, respectively. The proposed method was successfully applied to determine the three fungicides in real water samples including lake water, river water, as well as effluent and influent of wastewater treatment plant, with recoveries in the range of 74.94-96.11% at 5ng/mL spiking level. Besides to being environmental friendly, the high enrichment factor and the data quality obtained with the proposed method demonstrated its potential for application in multi residue analysis of fungicides in actual water samples.

  4. Highly selective ionic liquid-based microextraction method for sensitive trace cobalt determination in environmental and biological samples.

    PubMed

    Berton, Paula; Wuilloud, Rodolfo G

    2010-03-10

    A simple and rapid dispersive liquid-liquid microextraction procedure based on an ionic liquid (IL-DLLME) was developed for selective determination of cobalt (Co) with electrothermal atomic absorption spectrometry (ETAAS) detection. Cobalt was initially complexed with 1-nitroso-2-naphtol (1N2N) reagent at pH 4.0. The IL-DLLME procedure was then performed by using a few microliters of the room temperature ionic liquid (RTIL) 1-hexyl-3-methylimidazolium hexafluorophosphate [C(6)mim][PF(6)] as extractant while methanol was the dispersant solvent. After microextraction procedure, the Co-enriched RTIL phase was solubilized in methanol and directly injected into the graphite furnace. The effect of several variables on Co-1N2N complex formation, extraction with the dispersed RTIL phase, and analyte detection with ETAAS, was carefully studied in this work. An enrichment factor of 120 was obtained with only 6 mL of sample solution and under optimal experimental conditions. The resultant limit of detection (LOD) was 3.8 ng L(-1), while the relative standard deviation (RSD) was 3.4% (at 1 microg L(-1) Co level and n=10), calculated from the peak height of absorbance signals. The accuracy of the proposed methodology was tested by analysis of a certified reference material. The method was successfully applied for the determination of Co in environmental and biological samples.

  5. Determination of phthalate esters in edible oils by use of QuEChERS coupled with ionic-liquid-based dispersive liquid-liquid microextraction before high-performance liquid chromatography.

    PubMed

    Xie, Qilong; Liu, Shuhui; Fan, Yingying; Sun, Jianzhi; Zhang, Xiaoke

    2014-07-01

    A selective and low organic-solvent-consuming method of sample preparation combined with high-performance liquid chromatography with diode-array detection is introduced for analysis of phthalic acid esters in edible oils. Sample treatment involves initial liquid-liquid partitioning with acetonitrile, then QuEChERS cleanup by dispersive solid-phase extraction with primary secondary amine as sorbent. Preconcentration of the analytes is performed by ionic-liquid-based dispersive liquid-liquid microextraction, with the cleaned-up extract as disperser solvent and 1-hexyl-3-methylimidazolium hexafluorophosphate as extraction solvent. Under the optimized conditions, correlation coefficients (r) were 0.998-0.999 and standard errors (S y/x ) were 2.67-3.37 × 10(3) for calibration curves in the range 50-1000 ng g(-1). Detection limits, at a signal-to-noise ratio of 3, ranged from 6 to 9 ng g(-1). Intra-day and inter-day repeatability, expressed as relative standard deviation, were in the ranges 1.0-6.9 % and 2.4-9.4 %, respectively. Recovery varied between 84 % and 106 %. The developed method was successfully used for analysis of the analytes in 28 edible oils. The dibutyl phthalate content of four of the 28 samples (14 %) exceeded the specific migration limit established by domestic and international regulations.

  6. Quantitation of antioxidants in water samples using ionic liquid dispersive liquid-liquid microextraction followed by high-performance liquid chromatography-ultraviolet detection.

    PubMed

    Sobhi, Hamid Reza; Kashtiaray, Amir; Farahani, Hadi; Farahani, Mohammad Reza

    2011-01-01

    A simple and efficient method, ionic liquid-based dispersive liquid-liquid microextraction combined with high-performance liquid chromatography-ultraviolet detection (HPLC-UV), has been applied for the extraction and determination of some antioxidants (Irganox 1010, Irganox 1076 and Irgafos 168) in water samples. The microextraction efficiency factors were investigated and optimized: 1-hexyl-3-methylimidazolium hexafluorophosphate [C(6)MIM][PF(6)] (0.06 g) as extracting solvent, methanol (0.5 mL) as disperser solvent without salt addition. Under the selected conditions, enrichment factors up to 48-fold, limits of detection (LODs) of 5.0-10.0 ng/mL and dynamic linear ranges of 25-1500 ng/mL were obtained. A reasonable repeatability (RSD≤11.8%, n=5) with satisfactory linearity (r(2)≥0.9954) of the results illustrated a good performance of the presented method. The accuracy of the method was tested by the relative recovery experiments on spiked samples, with results ranging from 85 to 118%. Finally, the method was successfully applied for determination of the analytes in several real water samples.

  7. Ionic liquid-based microwave-assisted surfactant-improved dispersive liquid-liquid microextraction and derivatization of aminoglycosides in milk samples.

    PubMed

    Xu, Xu; Liu, Zhuang; Zhao, Xin; Su, Rui; Zhang, Yupu; Shi, Jiayuan; Zhao, Yajing; Wu, Lijie; Ma, Qiang; Zhou, Xin; Zhang, Hanqi; Wang, Ziming

    2013-02-01

    A green and simple method, ionic liquid-based microwave-assisted surfactant-improved dispersive liquid-liquid microextraction and derivatization was developed for the determination of aminoglycosides in milk samples. Nonionic surfactant Triton X-100 and ionic liquid 1-hexyl-3-methylimidazolium hexafluorophosphate were used as the disperser and extraction solvent, respectively. Extraction, preconcentration, and derivatization of aminoglycosides were carried out in a single step. Several experimental parameters, including type and volume of extraction solvent, type and concentration of surfactant, microwave power and irradiation time, concentration of derivatization reagent, and pH value and volume of buffer were investigated and optimized. Under the optimum experimental conditions, the linearities for determining the analytes were in the range 0.4-10.0 ng/mL for tobramycin, 1.0-25.0 ng/mL for neomycin, and 2.0-50.0 ng/mL for gentamicin, with the correlation coefficients ranging from 0.9991 to 0.9998. The LODs for the analytes were between 0.11 and 0.50 ng/mL. The present method was applied to the analysis of different milk samples, and the recoveries of aminoglycosides obtained were in the range 96.4-105.4% with the RSDs lower than 5.5%. The results showed that the present method was a rapid, convenient, and environmentally friendly method for the determination of aminoglycosides in milk samples.

  8. Predicting the partitioning of biological compounds between room-temperature ionic liquids and water by means of the solvation-parameter model.

    PubMed

    Padró, Juan M; Ponzinibbio, Agustín; Mesa, Leidy B Agudelo; Reta, Mario

    2011-03-01

    The partition coefficients, P(IL/w), for different probe molecules as well as for compounds of biological interest between the room-temperature ionic liquids (RTILs) 1-butyl-3-methylimidazolium hexafluorophosphate, [BMIM][PF(6)], 1-hexyl-3-methylimidazolium hexafluorophosphate, [HMIM][PF(6)], 1-octyl-3-methylimidazolium tetrafluoroborate, [OMIM][BF(4)] and water were accurately measured. [BMIM][PF(6)] and [OMIM][BF(4)] were synthesized by adapting a procedure from the literature to a simpler, single-vessel and faster methodology, with a much lesser consumption of organic solvent. We employed the solvation-parameter model to elucidate the general chemical interactions involved in RTIL/water partitioning. With this purpose, we have selected different solute descriptor parameters that measure polarity, polarizability, hydrogen-bond-donor and hydrogen-bond-acceptor interactions, and cavity formation for a set of specifically selected probe molecules (the training set). The obtained multiparametric equations were used to predict the partition coefficients for compounds not present in the training set (the test set), most being of biological interest. Partial solubility of the ionic liquid in water (and water into the ionic liquid) was taken into account to explain the obtained results. This fact has not been deeply considered up to date. Solute descriptors were obtained from the literature, when available, or else calculated through commercial software. An excellent agreement between calculated and experimental log P(IL/w) values was obtained, which demonstrated that the resulting multiparametric equations are robust and allow predicting partitioning for any organic molecule in the biphasic systems studied.

  9. Lipase-catalyzed esterification of ferulic Acid with oleyl alcohol in ionic liquid/isooctane binary systems.

    PubMed

    Chen, Bilian; Liu, Huanzhen; Guo, Zheng; Huang, Jian; Wang, Minzi; Xu, Xuebing; Zheng, Lifei

    2011-02-23

    Lipase-catalyzed synthesis of ferulic acid oleyl alcohol ester in an ionic liquid (IL)/isooctane system was investigated. Considerable bioconversion and volumetric productivity were achieved in inexpensive 1-hexyl-3-methylimidazolium hexafluorophosphate ([Hmim][PF(6)]) and 1-methyl-3-octylimidazolium hexafluorophosphate ([Omim][PF(6)]) mediated systems, and thus, the two types of ILs were selected for further optimization of variables. The results showed that, before reaching a maximum, the increase of ferulic acid concentration, temperature, or enzyme dosage led to an increase in volumetric productivity. Variations of the ratios of IL/isooctane and concentrations of oleyl alcohol also profoundly affected the volumetric productivity. To a higher extent, [Hmim][PF(6)]/isooctane and [Omim][PF(6)]/isooctane show similar reaction behaviors. Under the optimized reaction conditions (60 °C, 150 mg of Novozym 435 and 100 mg of molecular sieves), up to 48.50 mg/mL productivity of oleyl feruleate could be achieved for the [Hmim][PF(6)]/isooctane (0.5 mL/1.5 mL) system with a substrate concentration of ferulic acid of 0.08 mmol/mL and oleyl alcohol of 0.32 mmol; while an optimum volumetric productivity of 26.92 mg/mL was obtained for the [Omim][PF(6)]/ isooctane (0.5 mL/1.5 mL) system under a similar reaction condition other than the substrate concentrations of ferulic acid at 0.05 mmol/mL and oleyl alcohol at 0.20 mmol.

  10. Femtosecond Raman-Induced Kerr Effect Study of Temperature-Dependent Intermolecular Dynamics in Imidazolium-Based Ionic Liquids: Effects of Anion Species and Cation Alkyl Groups.

    PubMed

    Kakinuma, Shohei; Ishida, Tateki; Shirota, Hideaki

    2017-01-12

    The temperature dependence of the intermolecular vibrational dynamics in imidazolium-based ionic liquids (ILs) with 10 different anions was studied by femtosecond Raman-induced Kerr effect spectroscopy. For all ILs investigated in this study, the intensity in the low-frequency region below 50 cm(-1) increases, and the spectral density in the high-frequency region above 80 cm(-1) decreases (and shows a redshift) with increasing temperature. The first phenomenon would be attributed to the activation of the translational vibrational motions, whereas the second one is ascribed to the slowing librational motion of the imidazolium ring with increasing temperature. Calculated spectra of the density of states for the intermolecular vibrations of 1-butyl-3-methylimidazolium hexafluorophosphate, which is one of the experiment samples studied here, obtained by molecular dynamics simulation agreed well with the experimental results and confirmed the spectral assignments. When we compared the difference spectra between spectra measured at various temperatures and the spectrum measured at 293 K, a clear difference was found in the ∼50 cm(-1) region of the Kerr spectra of 1-butyl-3-methylimidazolium thiocyanate and 1-butyl-3-methylimidazolium dicyanamide from those of the other ILs. The difference might have originated from the librational motions of the corresponding anions. We also compared the temperature-dependent Kerr spectra of hexafluorophosphate salts of 1-butyl-3-methylimidazolium, 1-hexyl-3-methylimidazolium, and 1-heptyl-3-methylimidazolium cations. These ILs showed a similar temperature dependence, which was not affected by the alkyl group length. The temperature-dependent viscosities and glass transition temperatures of the ILs were also estimated to determine their fragilities.

  11. Modified ionic liquid cold-induced aggregation dispersive liquid-liquid microextraction combined with spectrofluorimetry for trace determination of ofloxacin in pharmaceutical and biological samples

    PubMed Central

    Zeeb, M.; Ganjali, M.R.; Norouzi, P.

    2011-01-01

    Background and the purpose of the study Ofloxacin is a quinolone synthetic antibiotic, which acts against resistant mutants of bacteria by inhibiting DNA gyrase. This antibacterial agent is widely used in the treatment of respiratory tract, urinary tract and tissue-based infections, which are caused by Gram-positive and Gram-negative bacteria. In this work, an efficient modified ionic liquid cold-induced aggregation dispersive liquid-liquid microextraction (M-IL-CIA-DLLME) was combined with spectrofluorimetry for trace determination of ofloxacin in real samples. Methods In this microextraction method, hydrophobic 1-hexyl-3-methylimidazolium hexafluorophosphate ([Hmim] [PF6]) ionic liquid (IL) as a microextraction solvent was dispersed into a heated sample solution containing sodium hexafluorophosphate (NaPF6) (as a common ion) and the analyte of interest. Afterwards, the resultant solution was cooled in an ice-water bath and a cloudy condition was formed due to a considerable decrease of IL solubility. After centrifuging, the enriched phase was introduced to the spectrofluorimeter for the determination of ofloxacin. Results and major conclusion In this technique, the performance of the microextraction method was not influenced by variations in the ionic strength of the sample solution (up to 30% w/v). Furthermore, [Hmim][PF6] IL was chosen as a green microextraction phase and an alternative to traditional toxic organic solvents. Different parameters affecting the analytical performance were studied and optimized. At optimum conditions, a relatively broad linear dynamic range of 0.15-125 µg l-1 and a limit of detection (LOD) of 0.029 µg l-1 were obtained. The relative standard deviation (R.S.D.) obtained for the determination of five replicates of the 10 ml solution containing 50 µg l-1 ofloxacin was 2.7%. Finally, the combined methodology was successfully applied to ofloxacin determination in actual pharmaceutical formulations and biological samples. PMID

  12. Synergistic Effect of 1-Butyl-3-methylimidazolium Hexafluorophosphate and DMSO in the SARA ATRP at Room Temperature Affording Very Fast Reactions and Polymers with Very Low Dispersity

    PubMed Central

    2015-01-01

    An unusual synergistic effect between 1-butyl-3-methylimidazolium hexafluorophosphate (BMIM-PF6) and dimethyl sulfoxide (DMSO) mixtures is reported for the supplemental activator and reducing agent atom transfer radical polymerization (SARA ATRP) of methyl acrylate (MA) using a catalytic system composed by sodium dithionate (Na2S2O4) and CuBr2/Me6TREN (Me6TREN: tris[2-(dimethylamino)ethyl]amine) at room temperature. To the best of our knowledge, the use of ionic liquids (IL) has never been reported for the SARA ATRP. The kinetic data obtained for a broad range of target molecular weights revealed very fast polymerization rates, low dispersity values (Đ < 1.05) and well-defined chain-end functionalities. PMID:25068078

  13. Ion chromatography electrospray ionization mass spectrometry method development and investigation of lithium hexafluorophosphate-based organic electrolytes and their thermal decomposition products.

    PubMed

    Kraft, Vadim; Grützke, Martin; Weber, Waldemar; Winter, Martin; Nowak, Sascha

    2014-08-08

    A method based on the coupling of ion chromatography (IC) and electrospray ionization mass spectrometry (ESI-MS) for the separation and determination of thermal decomposition products of LiPF6-based organic electrolytes is presented. The utilized electrolytes, LP30 and LP50, are commercially available and consist of 1mol/l LiPF6 dissolved in ethylene carbonate/dimethyl carbonate and ethylene carbonate/ethyl methyl carbonate, respectively. For the separation method development three ion chromatographic columns with different capacity and stationary phase were used and compared. Besides the known hydrolysis products of lithium hexafluorophosphate, several new organophosphates were separated and identified with the developed IC-ESI-MS method during aging investigations of the electrolytes. The chemical structures were elucidated with IC-ESI-MS/MS.

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

    PubMed Central

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

    2011-01-01

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

  15. Liquid structure of 1-alkyl-3-methylimidazolium-hexafluorophosphates by wide angle x-ray and neutron scattering and molecular dynamics

    NASA Astrophysics Data System (ADS)

    Macchiagodena, Marina; Gontrani, Lorenzo; Ramondo, Fabio; Triolo, Alessandro; Caminiti, Ruggero

    2011-03-01

    We report for the first time joined energy dispersed x-ray and neutron diffraction experiments on a series of (both protiated and selectively deuteriated) 1-alkyl-3-methylimidazolium hexafluorophosphate salts (alkyl = butyl, hexyl, octyl) at ambient conditions. The x-ray experimental data are used to optimize the interaction potential used for running molecular dynamics simulations on these systems. Such a potential leads to a good description of neutron scattering data from the samples without additional refinement, thus further validating the potential definition. The molecular dynamics simulations were used to access microscopic information on the morphology of the proposed systems, thus probing the role played by alkyl chain length on the structure. The comparison of x-ray weighted and neutron-weighted computed diffraction patterns allows the rationalization of several diffraction features. Further insight into cation-anion coordination and alkyl chain conformational equilibrium is provided on the basis of the MD-derived snapshots, confirming and extending previously obtained results on these issues.

  16. Comparison of the effect of ionic liquids containing hexafluorophosphate and trifluoroacetate anions on the inhibition of growth and oxidative stress in spring barley and common radish.

    PubMed

    Biczak, Robert; Pawłowska, Barbara; Feder-Kubis, Joanna; Telesiński, Arkadiusz

    2017-02-01

    Ionic liquids are a group of chemical compounds with chemical properties that are of great interest to various fields of science and industry. However, commercial use of these substances raises concern because they may threaten the natural ecosystems. The present study used 2 types of (-)-menthol-containing imidazolium chiral ionic liquids: 1-[(1R,2S,5R)-(-)-menthoxymethyl]-3-methylimidazolium hexafluorophosphate [Im-Men][PF6 ] and 1-[(1R,2S,5R)-(-)-menthoxymethyl]-3-methylimidazolium trifluoroacetate [Im-Men][CF3 CO2 ]. The effects of these compounds on growth and development of spring barley (Hordeum vulgare) and common radish (Raphanus sativus L. subvar. radicula Pers.) were investigated. The present study demonstrated that chiral ionic liquids produced a relatively high phytotoxicity, by shortening the plants' lengths and roots, thus causing a decline in the experimental plants' fresh weights. The investigated ionic liquids also led to a reduction in photosynthetic pigment levels, changes in hydrogen peroxide and malondialdehyde content, and changes in the activities of superoxide dismutase, catalase, and peroxidase in both plants. Changes in these enzymes were used to indicate oxidative stress levels in spring barley and common radish. It was demonstrated that imidazolium ionic liquid-induced phytotoxicity depended largely on the type of anion. The liquid [Im-Men][PF6 ] exhibited higher toxicity toward spring barley and common radish seedlings. Common radish was more resistant to chiral ionic liquids. Environ Toxicol Chem 2017;9999:1-11. © 2017 SETAC.

  17. Mechanical exfoliation of graphite in 1-butyl-3-methylimidazolium hexafluorophosphate (BMIM-PF6) providing graphene nanoplatelets that exhibit enhanced electrocatalysis

    NASA Astrophysics Data System (ADS)

    Hayes, William Ignatius; Lubarsky, Gennady; Li, Meixian; Papakonstantinou, Pagona

    2014-12-01

    A novel production method for graphene nanoplatelets (GPs) with enhanced electrocatalytic behaviour is presented. GPs show improvement in their oxygen reduction reaction (ORR) catalysis after prolonging the grinding of graphite in 1-butyl-3-methylimidazolium hexafluorophosphate (BMIM-PF6). Nitrogen doping of the GPs has inferred a further increase in ORR. The ORR onset potential, cathodic current magnitude and electron transfer efficiency have all improved as a direct consequence of increasing the graphite grinding duration from 30 min to 4 h. Atomic force microscopy has confirmed a decrease in the GP diameter and height as the grinding increases. Raman spectroscopy indicates a higher level of defects present after prolonging the graphite grinding in BMIM-PF6, most likely a result of the increased edge plane exposure. This increased edge plane appears to promote a higher level of nitrogen incorporation as the graphite grinding duration increases, as confirmed by X-ray photoelectron spectroscopy analysis. The stability of the cathodic current assessed by chronoamperometry analysis is higher for the GP and nitrogen doped graphene nanoplatelet (N-GP) samples than the platinum on carbon black (Pt/C). This study presents a novel process for the production of nitrogen doped graphene nanoplatelets, constituting a strategy for the up-scaled production of electrocatalysts.

  18. Ionic liquid-based ultrasound-assisted dispersive liquid-liquid microextraction combined with electrothermal atomic absorption spectrometry for a sensitive determination of cadmium in water samples

    NASA Astrophysics Data System (ADS)

    Li, Shengqing; Cai, Shun; Hu, Wei; Chen, Hao; Liu, Hanlan

    2009-07-01

    A new method was developed for the determination of cadmium in water samples using ionic liquid-based ultrasound-assisted dispersive liquid-liquid microextraction (IL-based USA-DLLME) followed by electrothermal atomic absorption spectrometry (ETAAS). The IL-based USA-DLLME procedure is free of volatile organic solvents, and there is no need for a dispersive solvent, in contrast to conventional DLLME. The ionic liquid, 1-hexyl-3-methylimidazolium hexafluorophosphate (HMIMPF 6), was quickly disrupted by an ultrasonic probe for 1 min and dispersed in water samples like a cloud. At this stage, a hydrophobic cadmium-DDTC complex was formed and extracted into the fine droplets of HMIMPF 6. After centrifugation, the concentration of the enriched cadmium in the sedimented phase was determined by ETAAS. Some effective parameters of the complex formation and microextraction, such as the concentration of the chelating agent, the pH, the volume of the extraction solvent, the extraction time, and the salt effect, have been optimized. Under optimal conditions, a high extraction efficiency and selectivity were reached for the extraction of 1.0 ng of cadmium in 10.0 mL of water solution employing 73 µL of HMIMPF 6 as the extraction solvent. The enrichment factor of the method is 67. The detection limit was 7.4 ng L - 1 , and the characteristic mass ( m0, 0.0044 absorbance) of the proposed method was 0.02 pg for cadmium (Cd). The relative standard deviation (RSD) for 11 replicates of 50 ng L - 1 Cd was 3.3%. The method was applied to the analysis of tap, well, river, and lake water samples and the Environmental Water Reference Material GSBZ 50009-88 (200921). The recoveries of spiked samples were in the range of 87.2-106%.

  19. Ionic liquid based dispersive liquid-liquid microextraction for the extraction of pesticides from bananas.

    PubMed

    Ravelo-Pérez, Lidia M; Hernández-Borges, Javier; Asensio-Ramos, María; Rodríguez-Delgado, Miguel Angel

    2009-10-23

    This paper describes a dispersive liquid-liquid microextraction (DLLME) procedure using room temperature ionic liquids (RTILs) coupled to high-performance liquid chromatography with diode array detection capable of quantifying trace amounts of eight pesticides (i.e. thiophanate-methyl, carbofuran, carbaryl, tebuconazole, iprodione, oxyfluorfen, hexythiazox and fenazaquin) in bananas. Fruit samples were first homogenized and extracted (1g) with acetonitrile and after suitable evaporation and reconstitution of the extract in 10 mL of water, a DLLME procedure using 1-hexyl-3-methylimidazolium hexafluorophosphate ([C(6)MIM][PF(6)]) as extraction solvent was used. Experimental conditions affecting the DLLME procedure (sample pH, sodium chloride percentage, ionic liquid amount and volume of disperser solvent) were optimized by means of an experimental design. In order to determine the presence of a matrix effect, calibration curves for standards and fortified banana extracts (matrix matched calibration) were studied. Mean recovery values of the extraction of the pesticides from banana samples were in the range of 69-97% (except for thiophanate-methyl and carbofuran, which were 53-63%) with a relative standard deviation lower than 8.7% in all cases. Limits of detection achieved (0.320-4.66 microg/kg) were below the harmonized maximum residue limits established by the European Union (EU). The proposed method, was also applied to the analysis of this group of pesticides in nine banana samples taken from the local markets of the Canary Islands (Spain). To the best of our knowledge, this is the first application of RTILs as extraction solvents for DLLME of pesticides from samples different than water.

  20. Pesticide extraction from table grapes and plums using ionic liquid based dispersive liquid-liquid microextraction.

    PubMed

    Ravelo-Pérez, Lidia M; Hernández-Borges, Javier; Herrera-Herrera, Antonio V; Rodríguez-Delgado, Miguel Angel

    2009-12-01

    Room temperature ionic liquids (RTILs) have been used as extraction solvents in dispersive liquid-liquid microextraction (DLLME) for the determination of eight multi-class pesticides (i.e. thiophanate-methyl, carbofuran, carbaryl, tebuconazole, iprodione, oxyfluorfen, hexythiazox, and fenazaquin) in table grapes and plums. The developed method involves the combination of DLLME and high-performance liquid chromatography with diode array detection. Samples were first homogenized and extracted with acetonitrile. After evaporation and reconstitution of the extract in water containing sodium chloride, a quick DLLME procedure that used the ionic liquid 1-hexyl-3-methylimidazolium hexafluorophosphate ([C(6)MIM][PF(6)]) and methanol was developed. The RTIL dissolved in a very small volume of acetonitrile was directed injected in the chromatographic system. The comparison between the calibration curves obtained from standards and from spiked sample extracts (matrix-matched calibration) showed the existence of a strong matrix effect for most of the analyzed pesticides. A recovery study was also developed with five consecutive extractions of the two types of fruits spiked at three concentration levels. Mean recovery values were in the range of 72-100% for table grapes and 66-105% for plum samples (except for thiophanate-methyl and carbofuran, which were 64-75% and 58-66%, respectively). Limits of detection (LODs) were in the range 0.651-5.44 microg/kg for table grapes and 0.902-6.33 microg/kg for plums, representing LODs below the maximum residue limits (MRLs) established by the European Union in these fruits. The potential of the method was demonstrated by analyzing 12 commercial fruit samples (six of each type).

  1. Amplified electrochemical sensor employing CuO/SWCNTs and 1-butyl-3-methylimidazolium hexafluorophosphate for selective analysis of sulfisoxazole in the presence of folic acid.

    PubMed

    Karimi-Maleh, Hassan; Amini, Fatemeh; Akbari, Ahmad; Shojaei, Moein

    2017-06-01

    In the present work, CuO nanoparticle decorated on single wall carbon nanotubes (CuO/SWCNTs) nanocomposite was successfully synthesized by chemical precipitation method and used for modification of carbon paste electrode (CPE) in the presence of 1-butyl-3-methylimidazolium hexafluorophosphate (1-B-3-MIHFP) liquid as binder. The novel voltammetric sensor was used as first electrochemical sensor for determination of sulfisoxazole (SFX). CuO/SWCNTs nanocomposite characterized by scanning electron microscopy (SEM) and X-ray powder diffraction (XRD) methods. Voltammetric methods such as cyclic voltammetry, square wave voltammetry (SWV), electrochemical impedance spectroscopy (EIS) and chronoamperometry were performed to assess the electrochemical performance of CuO/SWCNTs/1-B-3-MIHFP/CPE towards SFX in aqueous solution. The voltammetric obtained data confirm the significant enhancement of oxidation current and reduction overvoltage for electro-oxidation of SFX at a surface of CuO/SWCNTs/1-B-3-MIHFP/CPE. The square wave voltammetric response shows the linear increment of oxidation signals with an increase in the concentration of SFX in the range of 0.08-650μM with limit of detection 0.04μM. Using CuO/SWCNTs/1-B-3-MIHFP/CPE the SFX and folic acid peaks are separated ca. 0.72 and 0.895V, respectively; hence SFX can be detected in the presence of folic acid. Finally, the CuO/SWCNTs/1-B-3-MIHFP/CPE was used as high sensitive tools for analysis of SFX and folic acid in real samples.

  2. Two-dimensional ion chromatography for the separation of ionic organophosphates generated in thermally decomposed lithium hexafluorophosphate-based lithium ion battery electrolytes.

    PubMed

    Kraft, Vadim; Grützke, Martin; Weber, Waldemar; Menzel, Jennifer; Wiemers-Meyer, Simon; Winter, Martin; Nowak, Sascha

    2015-08-28

    A two-dimensional ion chromatography (IC/IC) technique with heart-cutting mode for the separation of ionic organophosphates was developed. These analytes are generated during thermal degradation of three different commercially available Selectilyte™ lithium ion battery electrolytes. The composition of the investigated electrolytes is based on 1M lithium hexafluorophosphate (LiPF6) dissolved in ethylene carbonate/dimethyl carbonate (50:50wt%, LP30), ethylene carbonate/diethyl carbonate (50:50wt%, LP40) and ethylene carbonate/ethyl methyl carbonate (50:50wt%, LP50). The organophosphates were pre-separated from PF6(-) anion on the low capacity A Supp 4 column, which was eluted with a gradient step containing acetonitrile. The fraction containing analytes was retarded on a pre-concentration column and after that transferred to the high capacity columns, where the separation was performed isocratically. Different stationary phases and eluents were applied on the 2nd dimension for the investigation of retention times, whereas the highly promising results were obtained with a high capacitive A Supp 10 column. The organophosphates generated in LP30 and LP40 electrolytes could be separated by application of an aqueous NaOH eluent providing fast analysis time within 35min. For the separation of the organophosphates of LP50 electrolyte due to its complexity a NaOH eluent containing a mixture of methanol/H2O was necessary. In addition, the developed two dimensional IC method was hyphenated to an inductively coupled plasma mass spectrometer (ICP-MS) using aqueous NaOH without organic modifiers. This proof of principle measurement was carried out for future quantitative investigation regarding the concentration of the ionic organophosphates. Furthermore, the chemical stability of several ionic organophosphates in water and acetonitrile at room temperature over a period of 10h was investigated. In both solvents no decomposition of the investigated analytes was observed and

  3. Design and Evaluation of Ionic Liquids as Novel CO2 Absorbents

    SciTech Connect

    Edward J. Maginn

    2006-01-12

    Progress from the fourth quarter 2005 activity on the project ''Design and Evaluation of Ionic Liquids as Novel CO{sub 2} Absorbents'' is provided. Major activities in three areas are reported: compound synthesis, property measurement and molecular modeling. Last quarter we reported the first ever experimental measurement of SO{sub 2} solubility in an ionic liquid. We showed that SO{sub 2} was very soluble in the ionic liquid 1-hexyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide ([hmim][Tf{sub 2}N]). This quarter, we have measured SO{sub 2} solubility in two more ionic liquids: 1-hexyl-3-methylpyridinium bis(trifluoromethanesulfonyl)imide ([hmpy][Tf{sub 2}N]) and 1-hexyl-3-methylimidazolium lactate ([hmim][lactate]). As with [hmim][Tf{sub 2}N], we find very high solubility of SO{sub 2} in these ionic liquids, but the lactate compounds shows the highest affinity for SO{sub 2} at low pressure. CO{sub 2} solubility was measured in three new compounds: [boronium][Tf{sub 2}N], 1-hexyl-3-methylimidazolium acesulfumate ([hmim][ace]), and 1-hexyl-3-methylimidazolium saccharinate ([hmim][sac]). We find relatively poor solubility of CO{sub 2} in the latter two compounds, and solubility comparable to [hmim][Tf{sub 2}N] in the boronium compound. We also synthesized four new ionic liquids this quarter and continued refinement of our molecular simulation technique for measuring gas solubility.

  4. X-ray and Synchrotron Diffraction Studies of 2-(Pyridin-2-yl)-1,10- Phenanthroline in the Role of Ligand for Two Copper Polymorphs or Hydrogen bonded with 2,2,6,6-Tetramethyl-4-oxopiperidinium Hexafluorophosphate

    SciTech Connect

    Krause, Jeanette A.; Zhao, Daoli; Chatterjee, Sayandev; Yeung, Bonnie M.; Connick, William B.; Collins, Sibrina N.

    2013-12-01

    Different extended packing motifs of dichloro-[2-(pyridin-2-yl)-1,10-phenanthroline]copper(II), CuCl2 (C17H11N3Cl2) are obtained depending on the crystallization conditions. A triclinic form (I) is obtained from dimethylformamide-diethyl ether or methanol whereas crystallization from dimethylformamide-water yields a monoclinic form (II). In each case, the CuII center is in a 5-coordinate, distorted square-pyramidal geometry. The extended packing for both forms can be described as a highly-offset π stacking arrangement with interlayer distances of 3.674 (3) and 3.679 (3) Å for (I) and (II), respectively. The reaction of diprotonated Pt(tmpip2NCN)Cl (tmpip2NCN = 2,6-bis(2,2,6,6-tetramethylpiperidylmethyl)- benzyl) with AgPF6 under acidic conditions followed by the addition of 2-(pyridin-2-yl)-1,10-phenanthroline, results in a hydrogen bonded co-crystal, 2,2,6,6-tetramethyl-4-oxopiperidinium hexafluorophosphate- 2-(pyridin-2-yl)-1,10-phenanthroline (1/1),C9H18NO+.PF6-.C17H11N3.(III). The extended packing maximizes π-π interactions in a parallel, faceto-face arrangement with an interlayer stacking distance of 3.4960 (14) Å.

  5. Dynamics of solvent and rotational relaxation of coumarin 153 in room-temperature ionic liquid 1-butyl-3-methylimidazolium hexafluorophosphate confined in Brij-35 micelles: a picosecond time-resolved fluorescence spectroscopic study.

    PubMed

    Chakraborty, Anjan; Seth, Debabrata; Chakrabarty, Debdeep; Setua, Palash; Sarkar, Nilmoni

    2005-12-15

    The dynamics of solvent and rotational relaxation of Coumarin 153 (C-153) in ionic liquid (IL) 1-butyl-3-methylimidazolium hexafluorophosphate ([bmim][PF6]) and in the ionic liquid confined in Brij-35 micellar aggregates have been investigated using steady-state and time-resolved fluorescence spectroscopy. We observed slower dynamics in the presence of micellar aggregates as compared to the pure IL. However, the slowing down in the solvation time on going from neat IL to IL-confined micelles is much smaller compared to that on going from water to water-confined micellar aggregates. The increase in solvation and rotational time in micelles is attributed to the increase in viscosity of the medium. The slow component is assumed to be dependent on the viscosity of the solution and involves large-scale rearrangement of the anions and cations while fast component is assumed to originate from the initial response of the anions during excitation. The slow component increases due to the increase in the viscosity of the medium and increase in fast component is probably due to the hydrogen bonding between the anions and polar headgroup of the surfactant. The dynamics of solvent relaxation was affected to a small extent due to the micelle formation.

  6. Use of a novel medium, the ionic liquid 1-butyl-3-trimethylsilylimidazolium hexafluorophosphate, for liquid-liquid extraction of lead in water and its determination by graphite furnace atomic absorption spectrometry.

    PubMed

    Zaijun, Li; Qiping, Peng; Haixia, Shan

    2007-01-01

    The ionic liquid 1-butyl-3-trimethylsilylimidazolium hexafluorophosphate, abbreviated as [C4tmsim][PF6], was developed as a novel medium for liquid-liquid extraction of lead(II) in water, in which dithizone was used as a metal chelator to form a neutral lead-dithizone complex. Under optimal conditions, the complex was extracted into the [C4tmsim][PF6] phase from aqueous solution and back-extracted with nitric acid solution into the aqueous phase that was used directly for the subsequent determination of Pb. The system using the ionic liquid demonstrated good extraction performance; the extraction and back-extraction efficiencies were 99.8 and 99.7%, respectively, for Pb(II) at 20 microg/L. The above procedure, including the extraction and back-extraction, was used to enrich trace levels of Pb(ll) in a relatively large volume of water samples (1000 mL water), and an enrichment factor of 400 was obtained. The enrichment coupled with graphite furnace atomic absorption spectrometry was successfully applied to the determination of Pb in water. The calibration graph was linear at levels near the detection limits up to > or = 100 ng/L Pb(II). The limits of quantitation and detection for lead in real water samples were 2.5 and 1.0 ng/L, respectively. Lead recoveries of 96.2-103.8% from spiked samples demonstrate the accuracy of the proposed method.

  7. A new 1,3-dibutylimidazolium hexafluorophosphate ionic liquid-based dispersive liquid-liquid microextraction to determine organophosphorus pesticides in water and fruit samples by high-performance liquid chromatography.

    PubMed

    He, Lijun; Luo, Xianli; Jiang, Xiuming; Qu, Lingbo

    2010-07-30

    The paper described a new ionic liquid, 1,3-dibutylimidazolium hexafluorophosphate, as extraction solvent for extraction and preconcentration of organophosphorus pesticides (fenitrothion, parathion, fenthion and phoxim) from water and fruit samples by dispersive liquid-liquid microextraction combined with high-performance liquid chromatography. The effects of experimental parameters, such as extraction solvent volume, disperser solvent and its volume, extraction and centrifugal time, sample pH, extraction temperature and salt addition, on the extraction efficiency were investigated. An extraction recovery of over 75% and enrichment factor of over 300-fold were obtained under the optimum conditions. The linearity relationship was also observed in the range of 5-1000 microgL(-1) with the correlation coefficients (r(2)) ranging from 0.9988 to 0.9999. Limits of detection were 0.01-0.05 microgL(-1) for four analytes. The relative standard deviations at spiking three different concentration levels of 20, 100 and 500 microgL(-1) varied from 1.3-2.7, 1.4-1.9 and 1.1-1.7% (n=7), respectively. Three real samples including tap water, Yellow River water and pear spiked at three concentration levels were analyzed and yielded recoveries ranging from 92.7-109.1, 95.0-108.2 and 91.2-108.1%, respectively.

  8. Interaction of ionic liquid with water in ternary microemulsions (Triton X-100/water/1-butyl-3-methylimidazolium hexafluorophosphate) probed by solvent and rotational relaxation of coumarin 153 and coumarin 151.

    PubMed

    Seth, Debabrata; Chakraborty, Anjan; Setua, Palash; Sarkar, Nilmoni

    2006-08-29

    The interaction of ionic liquid with water in 1-butyl-3-methylimidazolium hexafluorophosphate ([bmim][PF6])/Triton X-100 (TX-100)/H2O ternary microemulsions, i.e., "[bmim][PF6]-in-water" microregions of the microemulsions, has been studied by the dynamics of solvent and rotational relaxation of coumarin 153 (C-153) and coumarin 151 (C-151). The variation of the time constants of solvent relaxation of C-153 is very small with an increase in the [bmim][PF6]/TX-100 ratio (R). The rotational relaxation time of C-153 also remains unchanged in all micremulsions of different R values. The invariance of solvation and rotational relaxation times of C-153 indicates that the position of C-153 remains unaltered with an increase in R and probably the probe is located at the interfacial region of [bmim][PF6] and TX-100 in the microemulsions. On the other hand, in the case of C-151, with an increase in R the fast component of the solvation time gradually increases and the slow component gradually decreases, although the change in solvation time is small in comparison to that of microemulsions containing common polar solvents such as water, methanol, acetonitrile, etc. The rotational relaxation time of C-151 increases with an increase in R. This indicates that with an increase in the [bmim][PF6] content the number of C-151 molecules in the core of the microemulsions gradually increases. In general, the solvent relaxation time is retarded in this room temperature ionic liquid/water-containing microemulsion compared to that of a neat solvent, although retardation is very small compared to that of the solvent relaxation time of the conventional solvent in the core of the microemulsions.

  9. Structure of salts of lithium chloride and lithium hexafluorophosphate as solvates with pyridine and vinylpyridine and structural comparisons: (C5H5N)LiPF6, [p-(CH2=CH)C5H4N]LiPF6, [(C5H5N)LiCl]n, and [p-(CH2=CH)C5H4N]2Li(μ-Cl)2Li[p-(CH2=CH)C5H4N]2.

    PubMed

    Jalil, AbdelAziz; Clymer, Rebecca N; Hamilton, Clifton R; Vaddypally, Shivaiah; Gau, Michael R; Zdilla, Michael J

    2017-03-01

    Due to the flammability of liquid electrolytes used in lithium ion batteries, solid lithium ion conductors are of interest to reduce danger and increase safety. The two dominating general classes of electrolytes under exploration as alternatives are ceramic and polymer electrolytes. Our group has been exploring the preparation of molecular solvates of lithium salts as alternatives. Dissolution of LiCl or LiPF6 in pyridine (py) or vinylpyridine (VnPy) and slow vapor diffusion with diethyl ether gives solvates of the lithium salts coordinated by pyridine ligands. For LiPF6, the solvates formed in pyridine and vinylpyridine, namely tetrakis(pyridine-κN)lithium(I) hexafluorophosphate, [Li(C5H5N)4]PF6, and tetrakis(4-ethenylpyridine-κN)lithium(I) hexafluorophosphate, [Li(C7H7N)4]PF6, exhibit analogous structures involving tetracoordinated lithium ions with neighboring PF6(-) anions in the I-4 and Aea2 space groups, respectively. For LiCl solvates, two very different structures form. catena-Poly[[(pyridine-κN)lithium]-μ3-chlorido], [LiCl(C5H5N)]n, crystalizes in the P212121 space group and contains channels of edge-fused LiCl rhombs templated by rows of π-stacked pyridine ligands, while the structure of the LiCl-VnPy solvate, namely di-μ-chlorido-bis[bis(4-ethenylpyridine-κN)lithium], [Li2Cl2(C7H7N)4], is described in the P21/n space group as dinuclear (VnPy)2Li(μ-Cl)2Li(VnPy)2 units packed with neighbors via a dense array of π-π interactions.

  10. Structure and physical properties of [micro-tris(1,4-bis(tetrazol-1-yl)butane-N4,N4')iron(II)] bis(hexafluorophosphate), a new Fe(II) spin-crossover compound with a three-dimensional threefold interlocked crystal lattice.

    PubMed

    Grunert, C Matthias; Schweifer, Johannes; Weinberger, Peter; Linert, Wolfgang; Mereiter, Kurt; Hilscher, Gerfried; Müller, Martin; Wiesinger, Günter; van Koningsbruggen, Petra J

    2004-01-12

    [micro-Tris(1,4-bis(tetrazol-1-yl)butane-N4,N4')iron(II)] bis(hexafluorophosphate), [Fe(btzb)(3)](PF(6))(2), crystallizes in a three-dimensional 3-fold interlocked structure featuring a sharp two-step spin-crossover behavior. The spin conversion takes place between 164 and 182 K showing a discontinuity at about T(1/2) = 174 K and a hysteresis of about 4 K between T(1/2) and the low-spin state. The spin transition has been independently followed by magnetic susceptibility measurements, (57)Fe-Mössbauer spectroscopy, and variable temperature far and midrange FTIR spectroscopy. The title compound crystallizes in the trigonal space group P3 (No. 147) with a unit cell content of one formula unit plus a small amount of disordered solvent. The lattice parameters were determined by X-ray diffraction at several temperatures between 100 and 300 K. Complete crystal structures were resolved for 9 of these temperatures between 100 (only low spin, LS) and 300 K (only high spin, HS), Z = 1 [Fe(btzb)(3)](PF(6))(2): 300 K (HS), a = 11.258(6) A, c = 8.948(6) A, V = 982.2(10) A(3); 100 K (LS), a = 10.989(3) A, c = 8.702(2) A, V = 910.1(4) A(3). The molecular structure consists of octahedral coordinated iron(II) centers bridged by six N4,N4' coordinating bis(tetrazole) ligands to form three 3-dimensional networks. Each of these three networks is symmetry related and interpenetrates each other within a unit cell to form the interlocked structure. The Fe-N bond lengths change between 1.993(1) A at 100 K in the LS state and 2.193(2) A at 300 K in the HS state. The nearest Fe separation is along the c-axis and identical with the lattice parameter c.

  11. Ionic liquid foam floatation coupled with ionic liquid dispersive liquid-liquid microextraction for the separation and determination of estrogens in water samples by high-performance liquid chromatography with fluorescence detection.

    PubMed

    Zhang, Rui; Wang, Chuanliu; Yue, Qiaohong; Zhou, Tiecheng; Li, Na; Zhang, Hanqi; Hao, Xiaoke

    2014-11-01

    An ionic liquid foam floatation coupled with ionic liquid dispersive liquid-liquid microextraction method was proposed for the extraction and concentration of 17-α-estradiol, 17-β-estradiol-benzoate, and quinestrol in environmental water samples by high-performance liquid chromatography with fluorescence detection. 1-Hexyl-3-methylimidazolium tetrafluoroborate was applied as foaming agent in the foam flotation process and dispersive solvent in microextraction. The introduction of the ion-pairing and salting-out agent NH4 PF6 was beneficial to the improvement of recoveries for the hydrophobic ionic liquid phase and analytes. Parameters of the proposed method including concentration of 1-hexyl-3-methylimidazolium tetrafluoroborate, flow rate of carrier gas, floatation time, types and concentration of ionic liquids, salt concentration in samples, extraction time, and centrifugation time were evaluated. The recoveries were between 98 and 105% with relative standard deviations lower than 7% for lake water and well water samples. The isolation of the target compounds from the water was found to be efficient, and the enrichment factors ranged from 4445 to 4632. This developing method is free of volatile organic solvents compared with regular extraction. Based on the unique properties of ionic liquids, the application of foam floatation, and dispersive liquid-liquid microextraction was widened.

  12. An EQCM study of the electropolymerization of benzene in an ionic liquid and ion exchange characteristics of the resulting polymer film.

    PubMed

    Schneider, O; Bund, A; Ispas, A; Borissenko, N; Zein El Abedin, S; Endres, F

    2005-04-21

    The direct electropolymerization of benzene dissolved in the ionic liquid 1-hexyl-3-methylimidazolium tris(pentafluoroethyl)trifluorophosphate was studied at room temperature applying the electrochemical quartz-crystal microbalance technique. Analysis of the damping changes showed that the Sauerbrey equation could be applied for data evaluation. In the polymer, every third to fourth benzene ring carried a positive charge in the oxidized state. During electropolymerization, some ionic liquid was absorbed in the growing polymer. The redox behavior was characterized by wide peaks typical for conducting polymers. Charge neutrality of the polymer during redox cycling was maintained by anion and cation exchange with the ionic liquid. With increasing scan rate, cation exchange became more and more important.

  13. Electrosynthesis of poly(para)phenylene in an ionic liquid: cyclic voltammetry and in situ STM/tunnelling spectroscopy studies.

    PubMed

    Carstens, T; El Abedin, S Zein; Endres, F

    2008-02-22

    The electropolymerization of benzene in the air and water-stable ionic liquid 1-hexyl-3-methylimidazolium tris(pentafluoroethyl)trifluorophosphate (HMIm)FAP is investigated. The study comprises cyclic voltammetry, IR and in situ STM/tunnelling spectroscopy measurements. The IR results indicate that poly(para)phenylene is the end product of the electropolymerization of benzene in the employed ionic liquid. The resulting conjugation lengths of the product fall between 19 and 21. A polymer reference electrode is used successfully for the electrochemical polymerization of benzene. The first in situ STM results show that the electropolymerization of benzene in the ionic liquid can be probed on the nanoscale and the band gap of the prepared polymer can be determined. The electrodeposited polymer film obtained at a constant potential of 1.0 V vs PPP (polyparaphenylene) exhibits a band gap of 2.9+/-0.2 eV.

  14. Radiation stability of some room temperature ionic liquids

    NASA Astrophysics Data System (ADS)

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

    2011-05-01

    Radiation stability of some room temperature ionic liquids (RTILs) that find useful electrochemical applications in nuclear fuel cycle has been evaluated. The ionic liquids such as protonated betaine bis(trifluoromethylsulfonyl)imide (HbetNTf 2), aliquat 336 (tri-n-octlymethylammonium chloride), 1-butyl-3-methylimidazolium chloride (bmimCl), 1-hexyl-3-methylimidazolium chloride (hmimCl), N-butyl-N-methylpyrrolidinium bis(trifluoromethylsulfonyl)imide (BMPyNTf 2) and N-methyl-N-propylpiperidinium bis(trifluoromethylsulfonyl)imide (MPPiNTf 2) have been irradiated to various absorbed dose levels, up to 700 kGy. The effect of gamma radiation on these ionic liquids has been evaluated by determining the variations in the physical properties such as color, density, viscosity, refractive index and electrochemical window. The changes in density, viscosity and refractive index of these ionic liquids upon irradiation were insignificant; however, the color and electrochemical window varied significantly with increase of absorbed dose.

  15. Screen-printed electrode-based electrochemical detector coupled with in-situ ionic-liquid-assisted dispersive liquid-liquid microextraction for determination of 2,4,6-trinitrotoluene.

    PubMed

    Fernández, Elena; Vidal, Lorena; Iniesta, Jesús; Metters, Jonathan P; Banks, Craig E; Canals, Antonio

    2014-03-01

    A novel method is reported, whereby screen-printed electrodes (SPELs) are combined with dispersive liquid-liquid microextraction. In-situ ionic liquid (IL) formation was used as an extractant phase in the microextraction technique and proved to be a simple, fast and inexpensive analytical method. This approach uses miniaturized systems both in sample preparation and in the detection stage, helping to develop environmentally friendly analytical methods and portable devices to enable rapid and onsite measurement. The microextraction method is based on a simple metathesis reaction, in which a water-immiscible IL (1-hexyl-3-methylimidazolium bis[(trifluoromethyl)sulfonyl]imide, [Hmim][NTf2]) is formed from a water-miscible IL (1-hexyl-3-methylimidazolium chloride, [Hmim][Cl]) and an ion-exchange reagent (lithium bis[(trifluoromethyl)sulfonyl]imide, LiNTf2) in sample solutions. The explosive 2,4,6-trinitrotoluene (TNT) was used as a model analyte to develop the method. The electrochemical behavior of TNT in [Hmim][NTf2] has been studied in SPELs. The extraction method was first optimized by use of a two-step multivariate optimization strategy, using Plackett-Burman and central composite designs. The method was then evaluated under optimum conditions and a good level of linearity was obtained, with a correlation coefficient of 0.9990. Limits of detection and quantification were 7 μg L(-1) and 9 μg L(-1), respectively. The repeatability of the proposed method was evaluated at two different spiking levels (20 and 50 μg L(-1)), and coefficients of variation of 7 % and 5 % (n = 5) were obtained. Tap water and industrial wastewater were selected as real-world water samples to assess the applicability of the method.

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

    PubMed

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

    2013-10-21

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

  17. Low-temperature heat capacities of 1-alkyl-3-methylimidazolium bis(oxalato)borate ionic liquids and the influence of anion structural characteristics on thermodynamic properties.

    PubMed

    Yang, Miao; Zhao, Jun-Ning; Liu, Qing-Shan; Sun, Li-Xian; Yan, Pei-Fang; Tan, Zhi-Cheng; Welz-Biermann, Urs

    2011-01-07

    Two chelated orthoborate ionic liquids (ILs), 1-butyl-3-methylimidazolium bis(oxalato)borate ([Bmim][BOB]) and 1-hexyl-3-methylimidazolium bis(oxalato)borate ([Hmim][BOB]), were prepared and characterized. Their thermodynamic properties were studied using adiabatic calorimetry and differential scanning calorimetry (DSC). The thermodynamic properties of the two ILs were evaluated and compared with each other, and then with those of other [Bmim] type ILs. The results clearly indicate that for a given cation (or anion) and at a certain temperature, the more atoms in the anion (or cation), the higher the heat capacity; the higher glass-transition temperatures of [BOB] type ILs than others are mainly caused by the higher symmetry of the orthoborate anion structure. It is suggested that a high content of strong electronegative atoms and C(n) or C(nv) (n = 1,2,3,…,∞) point group symmetry in the anion are favorable for the design and synthesis of room temperature ILs with a wide liquid range.

  18. The acute toxic effects of imidazolium-based ionic liquids with different alkyl-chain lengths and anions on zebrafish (Danio rerio).

    PubMed

    Zhang, Cheng; Zhu, Lusheng; Wang, Jinhua; Wang, Jun; Zhou, Tongtong; Xu, Yaqi; Cheng, Chao

    2017-06-01

    With the increasing applications of ionic liquids (ILs), the toxicity of ILs has drawn increasing attention in recent years, especially the influences of different anions and alkyl-chain lengths on the acute toxicity to aquatic organisms. We performed a study on the acute toxicity of 1-alkyl-3-methylimidazolium nitrate ([Cnmim]NO3 (n=2, 4, 6, 8, 10, 12)), 1-hexyl-3-methylimidazolium ILs ([C6mim]R (R=Cl(-), Br(-), BF4(-), PF6(-))) to zebrafish (Danio rerio). We also evaluated the sensibility of the investigated animals and the stability of ILs in water via high performance liquid chromatography (HPLC, Agilent 1260, Agilent Technologies Inc., USA) to prove the reliability of the present study. The results illustrated that the test zebrafish (Danio rerio) were sensitive to the reference toxicant and that the investigated ILs in water were stable. The 50% lethal concentration (LC50) was used to represent the acute toxicity to zebrafish (Danio rerio). The present study showed that the highest toxic IL is [C12mim]NO3 and the lowest toxic IL is [C2mim]NO3 on Danio rerio. The LC50s for ILs with different anions had similar values. Accordingly, we believe that ILs with different alkyl-chain lengths cause greater effects than other anions on acute toxicity to aquatic organisms. Furthermore, the present study can also provide scientific methods for future studies to select and assess ILs.

  19. [Effects of imidazolium chloride ionic liquids on the acute toxicity and weight of earthworm].

    PubMed

    Huang, Ruo-Nan; Fan, Jun-Jie; Tu, Hong-Zhi; Tang, Ling-Yan; Liu, Hui-Jun; Xu, Dong-Mei

    2013-04-01

    Standard contact filter paper test of OECD and artificial soil test were used to study the acute lethal effect of three imidazolium chloride ionic liquids, 1-butyl- 3-methylimidazolium chloride ([Bmim] Cl), 1-hexyl- 3-methylimidazolium chloride ([Hmim] Cl), and 1-octyl- 3-methylimidazolium chloride ([Omim] Cl) on earthworm (Eisenia fetida), and the weight of the earthworms was measured after subtle exposure. The 24 h-LC50 values of [Bmim] Cl, [Hmim] Cl and [Omim] Cl using the contact filter paper method were 109.60, 50.38 and 7.94 microg x cm(-2), respectively. The 48 h-LC50 values were 98.52, 39.14 and 3.61 microg x cm(-2), respectively. Using the artificial soil method, the 7 d-LC50 values of [Bmim] Cl, [Hmim] Cl and [Omim] Cl were 447.78, 245.56 and 180.51 mg x kg(-1), respectively, and the 14 d-LC50 values were 288.42, 179.75, 150.35 mg x kg(-1), respectively. There were differences in poisoning symptoms of the three ionic liquids on earthworms. The growth of Eisenia fetida was inhibited and declined with increasing ionic liquid concentration. The toxicity of ionic liquids on Eisenia fetida increased with the length of carbon chain.

  20. Molecular dynamics simulations of the structural and thermodynamic properties of imidazolium-based ionic liquid mixtures.

    PubMed

    Méndez-Morales, T; Carrete, J; Cabeza, O; Gallego, L J; Varela, L M

    2011-09-29

    In this work, extensive molecular dynamics simulations of mixtures of alcohols of several chain lengths (methanol and ethanol) with the ionic liquids (ILs) composed of the cation 1-hexyl-3-methylimidazolium and several anions of different hydrophobicity degrees (Cl(-), BF(4)(-), PF(6)(-)) are reported. We analyze the influence of the nature of the anion, the length of the molecular chain of the alcohol, and the alcohol concentration on the thermodynamic and structural properties of the mixtures. Densities, excess molar volumes, total and partial radial distribution functions, coordination numbers, and hydrogen bond degrees are reported and analyzed for mixtures of the ILs with methanol and ethanol. The aggregation process is shown to be highly dependent on the nature of the anion and the size of the alcohol, since alcohol molecules tend to interact predominantly with the anionic part of the IL, especially in mixtures of the halogenated IL with methanol. Particularly, our results suggest that the formation of an apolar network similar to that previously reported in mixtures of ILs with water does not take place in mixtures with alcohol when the chloride anion is present, the alcohol molecules being instead homogeneously distributed in the polar network of IL. Moreover, the alcohol clusters formed in mixtures of [HMIM][PF(6)] with alcohol were found to have a smaller size than in mixtures with water. Additionally, we provide a semiquantitative analysis of the dependence of the hydrogen bonding degree of the mixtures on the alcohol concentration.

  1. Synthesis of surface molecularly imprinted polymer and the selective solid phase extraction of imidazole from its structural analogs.

    PubMed

    Zhu, Guifen; Fan, Jing; Gao, Yanbu; Gao, Xia; Wang, Jianji

    2011-05-30

    A surface molecularly imprinted polymer (MIP) was synthesized by using imidazole as the template and modified silica particles as the support material. The static adsorption, solid phase extraction (SPE) and high-performance liquid chromatography (HPLC) experiments were performed to investigate the adsorption properties and selective recognition characteristics of the polymer for imidazole and its structural analogs. It was shown that the maximum binding capacities of imidazole on the MIP and the non-imprinted polymer (NIP) were 312 and 169 μmol g(-1), respectively. The adsorption was fast and the adsorption equilibrium was achieved in 30 min. The binding process could be described by pseudo-second order kinetics. Compared with the corresponding non-imprinted polymer, the molecularly imprinted polymer exhibited much higher adsorption performance and selectivity for imidazole. The selective separation of imidazole from a mixture of 1-hexyl-3-methylimidazolium bromide ([C(6)mim][Br]) and 2,4-dichlorophenol could be achieved on the MIP-SPE column. The recoveries of imidazole and [C(6)mim][Br] were 97.6-102.7% and 12.2-17.3%, respectively, but 2,4-dichlorophenol could not be retained on the column. The surface molecularly imprinted polymer presented here may find useful application as a solid phase absorbent to separate trace imidazole in environmental water samples. This may also form the basis for our research program on the preparation and application of alkyl-imidazolium imprinted polymers.

  2. Binary diffusion coefficients for mixtures of ionic liquids [EMIM][N(CN)2], [EMIM][NTf2], and [HMIM][NTf2] with acetone and ethanol by dynamic light scattering (DLS).

    PubMed

    Rausch, Michael H; Hopf, Lisa; Heller, Andreas; Leipertz, Alfred; Fröba, Andreas P

    2013-02-28

    Mutual diffusivities for binary mixtures of the ionic liquids (ILs) [EMIM][N(CN)2] (1-ethyl-3-methylimidazolium dicyanimide), [EMIM][NTf2] (1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide), and [HMIM][NTf2] (1-hexyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide) with acetone and ethanol were studied in dependence on composition in the temperature range from 283.15 to 323.15 K, applying dynamic light scattering (DLS). The influence of experimental parameters on the achievable uncertainties was analyzed to ensure the acquisition of accurate data in adequate measurement times. For all probed systems, increasing binary diffusion coefficients were found for increasing temperatures. The systematic variation of anion and cation of the investigated ILs as well as a comparison with the literature data demonstrates the considerable influence of different ions on the resulting binary diffusion coefficients. Mutual diffusivities were found to be lower for the mixtures with ethanol than for those with acetone, which could be related to the formation of hydrogen bonds between ethanol and the ions. Most of the investigated IL solvent mixtures show increasing binary diffusion coefficients with increasing solvent concentration. For the mixtures of [EMIM][NTf2] with ethanol, however, a minimum of the mutual diffusivities was found in the ethanol mole fraction range from 0.7 to 0.8, which may hint at the vicinity of a critical demixing point. The viscosity of the pure ILs turned out to be no reliable indicator for the mutual diffusivity in mixtures with the same solvent.

  3. Double layer in room temperature ionic liquids: influence of temperature and ionic size on the differential capacitance and electrocapillary curves.

    PubMed

    Costa, Renata; Pereira, Carlos M; Silva, Fernando

    2010-09-28

    Differential capacity-potential curves, C(E), were obtained from electrochemical impedance spectra (12 kHz-2 Hz) for the interfaces between Hg and a series of alkyl imidazolium-based room temperature ionic liquids having the same anion, bis(trifluoromethanesulfonyl) imide: 1-ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl) imide [EMIM][Tf(2)N], 1-butyl-3-methylimidazolium bis(trifluoromethanesulfonyl) imide [BMIM][Tf(2)N], 1-hexyl-3-methylimidazolium bis(trifluoromethanesulfonyl) imide [HMIM][Tf(2)N]. The electrocapillary curves were obtained from drop time measurements and the values of the pzc were calculated. The pzc apparently becomes more negative as the imidazolium alkyl chain length increases. A small effect of the cation is seen on the C(E) curves at negative potentials. The effect of the aromatic nature of the cation is assessed by comparing 1-butyl-1-methylimidazolium bis(trifluoromethanesulfonyl) imide, with 1-butyl-3-methylpyrrolidinium bis(trifluoromethanesulfonyl) imide [BMPyr][Tf(2)N]. The effects of temperature on the capacitance, drop time electrocapillary curve and on the pzc were also obtained. The capacity was found to increase with increasing temperature in the whole range of accessible potentials.

  4. Successive disorder to disorder phase transitions in ionic liquid [HMIM][BF4] under high pressure

    NASA Astrophysics Data System (ADS)

    Zhu, Xiang; Yuan, Chaosheng; Li, Haining; Zhu, Pinwen; Su, Lei; Yang, Kun; Wu, Jie; Yang, Guoqiang; Liu, Jing

    2016-02-01

    In situ high-pressure Raman spectroscopy and synchrotron X-ray diffraction have been employed to investigate the phase behavior of ionic liquid, 1-hexyl-3-methylimidazolium tetrafluoroborate ([HMIM][BF4]) under high pressure up to 20 GPa at room temperature. With increasing pressure, some characteristic bands of [HMIM][BF4] disappear, and some characteristic bands of [HMIM][BF4] display non-monotonic pressure-induced frequency shift and non-monotonic variation of full width at half-maximum. Two successive phase transitions at ˜1.7 GPa and 7.3 GPa have been corroborated by the results above. The glass transition pressure (Pg) of [HMIM][BF4] at ˜7.3 GPa has been obtained by ruby R1 line broadening measurements and analysis of synchrotron X-ray diffraction patterns, and its glass transition mechanism is also analyzed in detail. These facts are suggestive of two successive disorder to disorder phase transitions induced by compression, that is, [HMIM][BF4] serves as a superpressurized glass under the pressure above 7.3 GPa, which is similar to the glassy state at low temperature, and a compression-induced liquid to liquid phase transition in [HMIM][BF4] occurs at ˜1.7 GPa. Besides, the conformational equilibrium of the GAAA conformer and AAAA conformer was converted easily in liquid [HMIM][BF4], while it was difficult to be influenced in glassy state.

  5. Molecular Functionalization of Graphene Oxide for Next-Generation Wearable Electronics.

    PubMed

    Zarrin, Hadis; Sy, Serubbabel; Fu, Jing; Jiang, Gaopeng; Kang, Keunwoo; Jun, Yun-Seok; Yu, Aiping; Fowler, Michael; Chen, Zhongwei

    2016-09-28

    Acquiring reliable and efficient wearable electronics requires the development of flexible electrolyte membranes (EMs) for energy storage systems with high performance and minimum dependency on the operating conditions. Herein, a freestanding graphene oxide (GO) EM is functionalized with 1-hexyl-3-methylimidazolium chloride (HMIM) molecules via both covalent and noncovalent bonds induced by esterification reactions and electrostatic πcation-π stacking, respectively. Compared to the commercial polymeric membrane, the thin HMIM/GO membrane demonstrates not only slightest performance sensitivity to the operating conditions but also a superior hydroxide conductivity of 0.064 ± 0.0021 S cm(-1) at 30% RH and room temperature, which was 3.8 times higher than that of the commercial membrane at the same conditions. To study the practical application of the HMIM/GO membranes in wearable electronics, a fully solid-state, thin, flexible zinc-air battery and supercapacitor are made exhibiting high battery performance and capacitance at low humidified and room temperature environment, respectively, favored by the bonded HMIM molecules on the surface of GO nanosheets. The results of this study disclose the strong potential of manipulating the chemical structure of GO to work as a lightweight membrane in wearable energy storage devices, possessing highly stable performance at different operating conditions, especially at low relative humidity and room temperature.

  6. Temperature Dependence of Low-Frequency Spectra in Molten Bis(trifluoromethylsulfonyl)amide Salts of Imidazolium Cations Studied by Femtosecond Raman-Induced Kerr Effect Spectroscopy.

    PubMed

    Shirota, Hideaki; Kakinuma, Shohei

    2015-07-30

    In this study, the temperature dependence of the low-frequency spectra of liquid bis(trifluoromethylsulfonyl)amide salts of the monocations 1-methyl-3-propylimidazolium and 1-hexyl-3-methylimidazolium and the dications 1,6-bis(3-methylimidazolium-1-yl)hexane and 1,12-bis(3-methylimidazolium-1-yl)dodecane has been investigated by means of femtosecond optical heterodyne-detected Raman-induced Kerr effect spectroscopy. The intensity in the low-frequency region below 20 cm(-1) in the spectra of the four ionic liquids increases with rising temperature. From a line-shape analysis of the broadened low-frequency spectra of the ionic liquids, it is clear that the lowest-frequency component, which peaks at approximately 5 cm(-1), contributes to the temperature dependence of the spectra. This implies that the activity of the intermolecular translational vibrational motion is increasing with rising temperature. It is also possible that decoupling in the crossover process between intermolecular vibrational motion and structural relaxation occurs as a result of a deterioration of the non-Markovian feature or the loss of memory caused by the higher temperature. The peak of the highest-frequency component, which is due mainly to the imidazolium ring libration, shifts to lower frequency with increasing temperature. This is attributed to weaker interactions of the ionic liquids at higher temperatures. Temperature-dependent viscosities from 293 to 353 K of the four ionic liquids have also been characterized.

  7. Use of magnetic effervescent tablet-assisted ionic liquid dispersive liquid-liquid microextraction to extract fungicides from environmental waters with the aid of experimental design methodology.

    PubMed

    Yang, Miyi; Wu, Xiaoling; Jia, Yuhan; Xi, Xuefei; Yang, Xiaoling; Lu, Runhua; Zhang, Sanbing; Gao, Haixiang; Zhou, Wenfeng

    2016-02-04

    In this work, a novel effervescence-assisted microextraction technique was proposed for the detection of four fungicides. This method combines ionic liquid-based dispersive liquid-liquid microextraction with the magnetic retrieval of the extractant. A magnetic effervescent tablet composed of Fe3O4 magnetic nanoparticles, sodium carbonate, sodium dihydrogen phosphate and 1-hexyl-3-methylimidazolium bis(trifluoromethanesulfonimide) was used for extractant dispersion and retrieval. The main factors affecting the extraction efficiency were screened by a Plackett-Burman design and optimized by a central composite design. Under the optimum conditions, good linearity was obtained for all analytes in pure water model and real water samples. Just for the pure water, the recoveries were between 84.6% and 112.8%, the limits of detection were between 0.02 and 0.10 μg L(-1) and the intra-day precision and inter-day precision both are lower than 4.9%. This optimized method was successfully applied in the analysis of four fungicides (azoxystrobin, triazolone, cyprodinil, trifloxystrobin) in environmental water samples and the recoveries ranged between 70.7% and 105%. The procedure promising to be a time-saving, environmentally friendly, and efficient field sampling technique.

  8. CO2 Absorption Using Fluorine Functionalized Ionic Liquids: Interplay of Hydrogen and σ-Hole Interactions.

    PubMed

    Rao, Soniya S; Gejji, Shridhar P

    2016-03-03

    Use of ionic liquids (ILs) for CO2 capture offers certain advantages over currently used methodologies and is of growing interest. With this perspective, ILs composed of S-ethyl-N,N,N',N'-tetramethylthiouronium ([ETT]) and 1-hexyl-3-methylimidazolium ([Hmim]) cations and tris(pentafluoroethyl)trifluorophosphate ([FEP]) anion have been investigated. The present work unravels the noncovalent interactions accompanying CO2 capture by these ILs. Electronic structure of ion pairs and their CO2 absorbed [ETT][FEP]·n(CO2) and [Hmim][FEP]·n(CO2) (n up to 30) complexes are derived. The anisotropy in molecular electrostatic potential dictates the binding of CO2 through the interplay of (i) halogen bonding (O···F) between electron deficient σ-holes on fluorines, (ii) electrostatic C···F interactions between electron deficient carbons of CO2 and the electron-rich fluorine atoms, and the (iii) hydrogen bonding (O···H) interactions from the cation. The manifestations of these interactions on binding energies, polarizabilities, and vibrational spectra of CO2 absorbed complexes are presented. Consequent "frequency shift" accompanying hydrogen and halogen bonding exhibit complementary characteristics in the infrared spectra of CO2 absorbed complexes. Correlation of binding energies to absorbed CO2 molecules further demonstrate that [Hmim] based ILs are more efficient for CO2 capture applications.

  9. The Overriding Roles of Concentration and Hydrophobic Effect on Structure and Stability of Heme Protein Induced by Imidazolium-Based Ionic Liquids.

    PubMed

    Jha, Indrani; Kumar, Awanish; Venkatesu, Pannuru

    2015-07-02

    Spectroscopic and molecular docking investigations were carried out to characterize the effect of imidazolium-based ionic liquids (ILs) with varying chain length of the cation on the thermal stability as well as spectroscopic behavior of heme protein hemoglobin (Hb). The goal of this work is to investigate the role of concentration of ILs, the effect of alkyl chain length of the cation, and the related Hofmeister series on the structure of Hb. To achieve this goal, a series of ILs possessing same Cl(-) anion and a set of cation [Cnmim](+) with increasing chain length such as 1-ethyl-3-methylimidazolium chloride ([Emim][Cl]), 1-butyl-3-methylimidazolium chloride ([Bmim][Cl]), 1-hexyl-3-methylimidazolium chloride ([Hmim][Cl]), and 1-decyl-3-methylimidazolium chloride ([Dmim][Cl]) were used in this study. It was observed that the stability of the protein was concentration dependent as well as the hydrophobic interactions between [Cnmim](+) of ILs, and the amino acid residues in the protein played a major role in protein unfolding. As a consequence, the destabilization tendency of the ILs toward the Hb increases with increasing chain length of the cation of ILs. Additionally, the cations of the ILs obeyed the Hofmeister series when arranged in the order of providing stability to Hb structure.

  10. CO2 capture in alkanolamine-RTIL blends via carbamate crystallization: route to efficient regeneration.

    PubMed

    Hasib-ur-Rahman, Muhammad; Larachi, Faïçal

    2012-10-16

    One of the major drawbacks of aqueous alkanolamine based CO(2) capture processes is the requirement of significantly higher energy of regeneration. This weakness can be overcome by separating the CO(2)-captured product to regenerate the corresponding amine, thus avoiding the consumption of redundant energy. Replacing aqueous phase with more stable and practically nonvolatile imidazolium based room-temperature ionic liquid (RTIL) provided a viable approach for carbamate to crystallize out as supernatant solid. In the present study, regeneration capabilities of solid carbamates have been investigated. Diethanolamine (DEA) carbamate as well as 2-amino-2-methyl-1-propanol (AMP) carbamate were obtained in crystalline form by bubbling CO(2) in alkanolamine-RTIL mixtures. Hydrophobic RTIL, 1-hexyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ([hmim][Tf(2)N]), was used as aqueous phase substituent. Thermal behavior of the carbamates was observed by differential scanning calorimetry and thermogravimetric analysis, while the possible regeneration mechanism has been proposed through (13)C NMR and FTIR analyses. The results showed that decomposition of DEA-carbamate commenced at lower temperature (∼55 °C), compared to that of AMP-carbamate (∼75 °C); thus promising easy regeneration. The separation of carbamate as solid phase can offer two-way advantage by letting less volume to regenerate as well as by narrowing the gap between CO(2) capture and amine regeneration temperatures.

  11. Ionic liquid-based totally organic solvent-free emulsification microextraction coupled with high performance liquid chromatography for the determination of three acaricides in fruit juice.

    PubMed

    Zhang, Jiaheng; Liang, Zhe; Guo, Hao; Gao, Peng; Lu, Runhua; Zhou, Wenfeng; Zhang, Sanbing; Gao, Haixiang

    2013-10-15

    A novel, totally organic solvent-free emulsification microextraction (TEME) technique using ionic liquids (ILs) is proposed in this study. Seven bis(trifluoromethylsulfonyl)imide ionic liquids were synthesized. After comparing the physicochemical properties of the ionic liquids and their application to microextraction experiments, 1-hexyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ([C6MIM][NTf2]), which has moderate surface tension and viscosity, was selected as the extraction solvent. The dispersion of ILs and mass transfer were accelerated by ultrasound irradiation and temperature control processes. Therefore, no dispersive organic solvent was needed. Several variables, such as ionic liquid volume, duration of the ultrasound extraction, dispersion temperature, ionic strength and centrifugation time were investigated and optimized. Under the optimum conditions, the calibration curve was linear in the range of 0.1-600 μg L(-1) for chlorfenapyr and fenpyroximate and 0.5-600 μg L(-1) for spirodiclofen, with correlation coefficients of 0.9994-0.9999. The enrichment factors were between 261 and 285. The limits of detection (LODs) were 0.02-0.06 μg L(-1). Real fruit juice samples (at fortified levels of 10 μg L(-1) and 30 μg L(-1)) were successfully analyzed using the proposed method. The relative recoveries and enrichment factors were in the range of 92-104%.

  12. Ionic liquid-assisted bidirectional regulation strategy for carbon quantum dots (CQDs)/Bi4O5I2 nanomaterials and enhanced photocatalytic properties.

    PubMed

    Ji, Mengxia; Xia, Jiexiang; Di, Jun; Wang, Bin; Yin, Sheng; Xu, Li; Zhao, Junze; Li, Huaming

    2016-09-15

    In this study, novel visible-light-driven carbon quantum dots (CQDs)/Bi4O5I2 material has been prepared via a reactable ionic liquid 1-hexyl-3-methylimidazolium iodide ([Hmim]I) assisted bidirectional regulation solvothermal method. This is the first time for the preparation of CQDs/Bi4O5I2 material with halogen and CQDs bidirectional regulation at the same time. With CQDs modified on the surface of Bi4O5I2, fast transfer of photogenerated charges and low recombination of photo-induced electron-hole pairs facilitated the enhancement of photodegradation activity. At the same time, the introduction of CQDs made the electrons occupied in high-energy potential on the conduction band of Bi4O5I2 transfer to the reaction center CQDs and the molecular oxygen can be thus activated. The enhanced mechanisms for the active species (holes, hydroxyl and superoxide radicals) during the photocatalytic reaction under visible irradiation were analyzed using DRS analysis, electron spin resonance (ESR) technique and free radicals trapping experiments.

  13. Effect of the environmental humidity on the bulk, interfacial and nanoconfined properties of an ionic liquid.

    PubMed

    Jurado, L Andres; Kim, Hojun; Rossi, Antonella; Arcifa, Andrea; Schuh, Jonathon K; Spencer, Nicholas D; Leal, Cecilia; Ewoldt, Randy H; Espinosa-Marzal, Rosa M

    2016-08-10

    With reference to our previous surface-force study on 1-hexyl-3-methylimidazolium ethylsulfate ([HMIM] EtSO4) using an extended surface forces apparatus, which showed an ordered structure within the nanoconfined dry ionic liquid (IL) between mica surfaces that extended up to ∼60 nm from the surface, this work focuses on the influence of the environmental humidity on the bulk, interfacial and nanoconfined structure of [HMIM] EtSO4. Infrared spectroscopy and rheometry reflect the changes in chemical and physical properties of the bulk IL due to the uptake of water when exposed to ambient humidity, while wide-angle X-ray scattering shows a mild swelling of the bulk nanostructure, and the AFM sharp tip reveals an additional surface layer at the mica-IL interface. When the water-containing [HMIM] EtSO4 is nanoconfined between two mica surfaces, no long-range order is detected, in contrast to the results obtained for the dry IL, which demonstrates that the presence of water can prevent the liquid-to-solid transformation of this IL. A combination of techniques and the calculated Bjerrum length indicate that water molecules weaken interionic electrostatic and hydrogen-bonding interactions, which lessens ion-ion correlations. Our work shows that the solid-like behavior of the nanoconfined IL strongly depends on the presence of absorbed water and hence, it has implications with regard to the correct interpretation of laboratory studies and their extension to real applications in lubrication.

  14. Magnetic ionic liquid-based dispersive liquid-liquid microextraction for the determination of triazine herbicides in vegetable oils by liquid chromatography.

    PubMed

    Wang, Yuanpeng; Sun, Ying; Xu, Bo; Li, Xinpei; Jin, Rui; Zhang, Hanqi; Song, Daqian

    2014-12-19

    Magnetic ionic liquid-based dispersive liquid-liquid microextraction (MIL-based DLLME) was developed for extracting triazine herbicides from vegetable oils. The MIL, 1-hexyl-3-methylimidazolium tetrachloroferrate ([C6mim] [FeCl4]), was used as the microextraction solvent. The magnetic separation time was shortened by simply mixing carbonyl iron powder with the MIL in the sample after DLLME. The effects of several important experimental parameters, including the amount of MIL, the time of ultrasonic extraction, the type and the volume of cleanup solvent were investigated. The MIL-based DLLME coupled with liquid chromatography gave the limits of detection of 1.31-1.49ngmL(-1) and limits of quantification of 4.33-4.91 ng mL(-1) for triazine herbicides. When the present method was applied to the analysis of vegetable oil samples, the obtained recoveries were in the range of 81.8-114.2% and the relative standard deviations were lower than 7.7%. Compared with existing methods, the performances achieved by the present method were acceptable.

  15. Video-microscopic observation of ionic liquid/alcohol interface and the corresponding molecular simulation study

    NASA Astrophysics Data System (ADS)

    Zhu, Peixi

    This research is aimed at studying the ionic liquid/n-pentanol interface via video-microscopy and molecular dynamic simulations. Understanding the interfacial phenomena and interfacial transport between ionic liquids and other liquids is of interest to the development and application of ionic liquids in a number of areas. One such area is the biphasic hydroformylation of alkenes to obtain alcohol and aldehyde, in which case ionic liquid is the reaction medium where a catalyst resides. The dissolution of an ionic liquid into an alcohol was studied by microscopically observing and measuring the shrinking of a micropipette-produced droplet in real time. Although microscopic investigation of droplet dissolution has been studied before, no attempt had been made to measure the diffusion coefficient D of the droplet species in the surrounding medium. A key finding of this work is that the Epstein-Plesset mathematical model, which describes the dissolution of a droplet/bubble in another fluid medium, can be used to measure D. Other experimental studies of the ionic liquid/alcohol system include electrical conductivity and UV-visible spectroscopy measurements of solutions of 1-hexyl-3-methylimidazolium tetrafluoroborate in n-pentanol. Those experiments were done in order to understand the molecular state of the particular ionic liquid in n-pentanol, as well as obtaining the dissociation constant K of such weak electrolyte solution. The experimental results provide an entry to the assessment of ionic liquid interaction with n-pentanol at molecular scale. Subsequently, molecular dynamics simulation was implemented for the investigation of such interaction. The computation started with simulation of the bulk phase of 1-butyl-3-methylimidazolium tetrafluoroborate, an affine ionic liquid on which molecular simulations had already been reported. A generalized probability based on Fuoss approximation for the closest ion to a distinguished countercharge ion was developed. In

  16. Effect of the structure of imidazolium cations in [BF4](-)-type ionic liquids on direct electrochemistry and electrocatalysis of horseradish peroxidase in Nafion films.

    PubMed

    Lu, Lu; Huang, Xirong; Qu, Yinbo

    2011-10-01

    The direct electrochemistry and bioelectrocatalysis of horseradish peroxidase (HRP) in Nafion films at glassy carbon electrode (GCE) was investigated in three [BF(4)](-)-type room-temperature ionic liquids (ILs) to understand the structural effect of imidazolium cations. The three ILs are 1-ethyl-3-methylimidazolium tetrafluoroborate ([Emim][BF(4)]), 1-butyl-3-methylimidazolium tetrafluoroborate ([Bmim][BF(4)]) and 1-hexyl-3-methylimidazolium tetrafluoroborate ([Hmim][BF(4)]). A small amount of water in the three ILs is indispensable for maintaining the electrochemical activity of HRP in Nafion films, and the optimum water contents decrease with the increase of alkyl chain length on imidazole ring. Analysis shows that the optimum water contents are primarily determined by the hydrophilicity of ILs used. In contrast to aqueous medium, ILs media facilitate the direct electron transfer of HRP, and the electrochemical parameters obtained in different ILs are obviously related to the nature of ILs. The direct electron transfer between HRP and GCE is a surface-confined quasi-reversible single electron transfer process. The apparent heterogeneous electron transfer rate constant decreases gradually with the increase of alkyl chain length on imidazole ring, but the changing extent is relatively small. The electrocatalytic reduction current of H(2)O(2) at the present electrode decreases obviously with the increase of alkyl chain length, and the mass transfer of H(2)O(2) via diffusion in ILs should be responsible for the change. In addition, the modified electrode has good stability and reproducibility; the ability to tolerate high levels of F(-) has been greatly enhanced due to the use of Nafion film. When an appropriate mediator is included in the sensing layer, a sensitive nonaqueous biosensor could be fabricated.

  17. Thermal Conductivity of Ionic Liquids: Measurement and Prediction

    NASA Astrophysics Data System (ADS)

    Fröba, A. P.; Rausch, M. H.; Krzeminski, K.; Assenbaum, D.; Wasserscheid, P.; Leipertz, A.

    2010-12-01

    This study reports thermal-conductivity data for a series of [EMIM] (1-ethyl-3-methylimidazolium)-based ionic liquids (ILs) having the anions [NTf2] (bis(trifluoromethylsulfonyl)imide), [OAc] (acetate), [N(CN)2] (dicyanimide), [C(CN)3] (tricyanomethide), [MeOHPO2] (methylphosphonate), [EtSO4] (ethylsulfate), or [OcSO4] (octylsulfate), and in addition for ILs with the [NTf2]-anion having the cations [HMIM] (1-hexyl-3-methylimidazolium), [OMA] (methyltrioctylammonium), or [BBIM] (1,3-dibutylimidazolium). Measurements were performed in the temperature range between (273.15 and 333.15) K by a stationary guarded parallel-plate instrument with a total measurement uncertainty of 3 % ( k = 2). For all ILs, the temperature dependence of the thermal conductivity can well be represented by a linear equation. While for the [NTf2]-based ILs, a slight increase of the thermal conductivity with increasing molar mass of the cation is found at a given temperature, the [EMIM]-based ILs show a pronounced, approximately linear decrease with increasing molar mass of the different probed anions. Based on the experimental data obtained in this study, a simple relationship between the thermal conductivity, molar mass, and density is proposed for the prediction of the thermal-conductivity data of ILs. For this, also densities were measured for [EMIM][OAc], [EMIM][C(CN)3], and [HMIM][NTf2]. The mean absolute percentage deviation of all thermal-conductivity data for ILs found in the literature from the proposed prediction is about 7 %. This result represents a convenient simplification in the acquisition of thermal conductivity information for the enormous amount of structurally different IL cation/anion combinations available.

  18. Understanding Structure-Property Correlation in Monocationic and Dicationic Ionic Liquids through Combined Fluorescence and Pulsed-Field Gradient (PFG) and Relaxation NMR Experiments.

    PubMed

    Kumar Sahu, Prabhat; Ghosh, Arindam; Sarkar, Moloy

    2015-11-05

    Steady state, time-resolved fluorescence and NMR experiments are carried out to gain deeper insights into the structure-property correlation in structurally similar monocationic and dicationic room-temperature ionic liquids (RTILs). The excitation wavelength dependent fluorescence response of fluorophore in 1-methy-3-propyllimidazolium bis(trifluoromethylsulfonyl)amide [C3MIm][NTf2] is found to be different from that of 1,6-bis(3-methylimidazolium-1-yl)hexane bis(trifluoromethylsulfonyl)amide [C6(MIm)2][NTf2]2 and 1-hexyl-3-methylimidazolium bis(trifluoromethylsulfonyl)amide [C6MIm][NTf2]. The outcomes of the present solvent dynamics study in [C3MIm][NTf2] when compared with those in [C6(MIm)2][NTf2]2 and in [C6MIm][NTf2] from our previous studies (Phys. Chem. Chem. Phys. 2014, 16, 12918-12928) indicate the involvement of dipolar rotation of imidazolium cation during solvation. To correlate the findings of solvation dynamics study with the dipolar rotation of the imidazolium ring, pulsed-field gradient (PFG)-NMR technique for translational diffusion coefficient measurement and (1)H as well as (19)F spin-lattice relaxation measurements are employed. NMR investigation reveals that an ultrafast component of solvation can be related to the dipolar rotation of imidazolium cation; hence, the role of dipolar rotation of cations in governing the dynamics of solvation in ILs cannot be ignored. Analysis of the rotational relaxation dynamics data by the Stokes-Einstein-Debye hydrodynamic theory unveils distinctive features of solute-solvent interaction in [C3MIm][NTf2] and [C6(MIm)2][NTf2]2.

  19. Evaluation of the Capability of Ionic Liquid-Amino Acid Aqueous Systems for the Formation of Aqueous Biphasic Systems and Their Applications in Extraction.

    PubMed

    Noshadi, Sajjad; Sadeghi, Rahmat

    2017-03-03

    In order to obtain further experimental evidence for better understanding of the molecular mechanisms responsible for the soluting-out effect phenomena in the ternary systems composed of ionic liquid (IL), amino acid and water, systematic studies on the vapor-liquid, liquid-liquid and solid-liquid equilibrium behavior of aqueous solutions of several ILs were carried out in the presence of a range of amino acids. Water activities for binary and ternary aqueous solutions containing 1-butyl-3-methylimidazolium chloride, [C4mim]Cl, 1-hexyl-3-methylimidazolium chloride, [C6mim]Cl, 1-butyl-3-methyl-imidazolium trifluoromethanesulfonate, [C4mim][CF3SO3], l-serine, glycine, alanine, and l-proline were measured using both vapor pressure osmometry and isopiestic methods. All the ternary IL + amino acid + water systems show the negative deviations from the semi-ideal behavior and therefore the soluting-out effects have been seen in these systems. In the case of [C4mim][CF3SO3] + amino acids aqueous systems, the IL is soluted-out by the amino acids and the soluting-out effect appears by aqueous biphasic systems formation. For these systems, the phase diagram and partition coefficient of caffeine were measured at 298.15 K. However, for the [C4mim]Cl and [C6mim]Cl containing systems, the amino acids are soluted-out by the ILs and the soluting-out effect appears by precipitation of the amino acids from the solution and solubilities of the amino acids in aqueous solutions decrease in the presence of [C4mim]Cl and [C6mim]Cl.

  20. Thermodynamical and structural properties of binary mixtures of imidazolium chloride ionic liquids and alcohols from molecular simulation

    NASA Astrophysics Data System (ADS)

    Raabe, Gabriele; Köhler, Jürgen

    2008-10-01

    We have performed molecular dynamics simulations to determine the densities, excess energies of mixing, and structural properties of binary mixtures of the 1-alkyl-3-methylimidazolium chloride ionic liquids (ILs) [amim][Cl] and ethanol and 1-propanol in the temperature range from 298.15to363.15K. As in our previous work [J. Chem. Phys. 128, 154509 (2008)], our simulation studies are based on a united atom model from Liu et al. [Phys. Chem. Chem. Phys. 8, 1096 (2006)] for the 1-ethyl- and 1-butyl-3-methylimidazolium cations [emim+] and [bmim+], which we have extended to the 1-hexyl-3-methylimidazolium [hmim+] cation and combined with parameters of Canongia Lopes et al. [J. Phys. Chem. B 108, 2038 (2004)] for the chloride anion [Cl-] and the force field by Khare et al. for the alcohols [J. Phys. Chem. B 108, 10071 (2004)]. With this, we provide both prediction for the densities of the mixtures that have mostly not been investigated experimentally yet and a molecular picture of the interactions between the alcohol molecules and the ions. The negative excess energies of all mixtures indicate an energetically favorable mixing of [amim][Cl] ILs and alcohols. To gain insight into the nonideality of the mixtures on the molecular level, we analyzed their local structures by radial and spatial distribution functions. These analyses show that the local ordering in these mixtures is determined by strong hydrogen-bond interactions between the chloride anion and the hydroxyls of the alcohols, enhanced interactions between the anion and the charged domain of the cation, and an increasing aggregation of the nonpolar alkyl tails of the alcohols and the cations with increasing cation size, which results in a segregation of polar and nonpolar domains.

  1. Ionic liquid based dispersive liquid-liquid microextraction coupled with micro-solid phase extraction of antidepressant drugs from environmental water samples.

    PubMed

    Ge, Dandan; Lee, Hian Kee

    2013-11-22

    Ionic liquid-dispersive liquid-liquid microextraction combined with micro-solid phase extraction (IL-DLLME-μ-SPE), and high-performance liquid chromatography (HPLC) was developed for the determination of tricyclic antidepressants (TCAs) in water samples. Two hundred microliters of an organic solvent (as disperser solvent) and 20 μl of 1-hexyl-3-methylimidazolium tris(pentafluoroethyl)trifluorophosphate were injected into a 5.0 ml sample for sonication-assisted DLLME. After this, a μ-SPE device, containing a novel material zeolite imidazolate framework 4 (ZIF-4), was added into the sample solution and 1 min of vortex-assisted extraction was performed. After 5 min of sonication-assisted desorption, 10 μl of desorption solvent was injected into a HPLC system for analysis. A characteristic property of DLLME-VA-μ-SPE is that any organic solvent and solid sorbent immiscible with water can be used. Special apparatus, or conical-bottom test tubes, and tedious procedures conventionally associated with DLLME such as centrifugation, or refrigeration of solvent are not necessary in the present approach. A novel material, ZIF-4 was employed as μ-SPE sorbent. Under the optimized conditions, the calibration curves were linear in the range of 1-1000 μg/L. The relative standard deviations and the limits of detection were in the range of 1.5% and 7.8% and 0.3 and 1 μg/L, respectively. The relative recoveries of canal water samples, spiked with drugs, were in the range of 94.3% and 114.7%. The results showed that IL-DLLME-μ-SPE was suitable for the determination of TCAs in water samples.

  2. Separation of carbon dioxide and sulfur dioxide gases using room-temperature ionic liquid (hmim)(Tf2N)

    SciTech Connect

    A. Yokozeki; Mark B. Shiflett

    2009-09-15

    To understand capturing and/or enhanced gaseous selectivity of industrial flue gases containing CO{sub 2} and SO{sub 2} using room-temperature ionic liquids, we have developed a ternary equation of state (EOS) model for a CO{sub 2}/SO{sub 2}/1-hexyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ((hmim)(Tf2N)) system. The present model is based on a generic RK (Redlich-Kwong) EOS, with empirical binary interaction parameters of each binary system. These interaction parameters have been determined using our measured VLE (vapor-liquid-equilibrium) data for SO{sub 2}/(hmim)(Tf2N) and CO{sub 2}/(hmim)(Tf2N) and literature data for CO{sub 2}/SO{sub 2}. The validity of the present EOS has been checked by conducting ternary VLE experiments for the present system. With this EOS, isothermal ternary phase diagrams and solubility (VLE) behaviors have been calculated for various (T, P, and feed compositions) conditions. For large and equimolar CO{sub 2}/SO{sub 2} mole ratios, the gaseous selectivity is nearly independent of the amount of the ionic liquid addition. However, for small CO{sub 2}/SO{sub 2} mole ratios the addition of the ionic liquid significantly increases the selectivity. The strong absorption of CO{sub 2} and SO{sub 2} in this ionic liquid may be practical for the simultaneous capture of these acid gases. 39 refs., 8 figs., 4 tabs.

  3. Molecular modeling of imidazolium-based [Tf2N-] ionic liquids: microscopic structure, thermodynamic and dynamic properties, and segmental dynamics.

    PubMed

    Logotheti, Georgia-Evangelia; Ramos, Javier; Economou, Ioannis G

    2009-05-21

    The microscopic structure, thermodynamic properties, local segmental dynamics, and self-diffusion coefficients of three ionic liquids (ILs) with a common anion, namely, the bis(trifluoromethylsulfonyl) imide ([Tf2N-]), and imidazolium-based cations that differ in the alkyl tail length, namely, the 1-butyl-3-methylimidazolium ([C4mim+]), the 1-hexyl-3-methylimidazolium ([C6mim+]), and the 1-octyl-3-methylimidazolium ([C8mim+]), are calculated over the temperature range of 298.15-333.15 K and pressure range of 0.1-60 MPa. Quantum calculations based on density functional theory are performed on isolated ion pairs, and minimum energy conformers are identified. Electronic density results are used to estimate the electrostatic potential of a molecular force field that is used subsequently for long molecular dynamics (MD) simulations of bulk ILs. Thermodynamic properties calculated from MD are shown to be in excellent agreement for the bulk density and good agreement for derivative properties when compared to experimental data. The new force field is an improvement over earlier ones for the same ILs. The microscopic structure as expressed through the radial distribution function is thoroughly calculated, and it is shown that the bulk structure characteristics are very similar to those obtained from the quantum calculations on isolated ion pairs. The segmental dynamics expressed in terms of bond and torsion angle decorrelation is shown to assume a broad range of characteristic times. Molecular segments in the alkyl tail of the cations are significantly faster than segments in the vicinity of the imidazolium ring. Finally, the new force field predicts accurately the self-diffusion coefficients of the cations and the anions over the entire temperature range examined, thus confirming its validity for a broad range of physical properties.

  4. Ionic liquid-assisted separation and determination of selenium species in food and beverage samples by liquid chromatography coupled to hydride generation atomic fluorescence spectrometry.

    PubMed

    Castro Grijalba, Alexander; Fiorentini, Emiliano F; Wuilloud, Rodolfo G

    2017-03-31

    Different ionic liquids (ILs) were assayed as mobile phase modifiers for the separation and determination of selenite [Se(IV)], selenate [Se(VI)], selenomethionine (SeMet) and Se-methylselenocysteine (SeMeSeCys) by reversed-phase high-performance liquid chromatography coupled to hydride generation atomic fluorescence spectrometry (RP-HPLC-HG-AFS). The use of several ILs: 1-butyl-3-methylimidazolium chloride, 1-hexyl-3-methylimidazolium chloride ([C6mim]Cl), 1-octyl-3-methylimidazolium chloride, 1-dodecyl-3-methylimidazolium bromide, 1-hexadecyl-3-methylimidazolium bromide and tributyl(methyl)phosphonium methylsulphate was evaluated. Also, the effect of pH, buffer type and IL concentration on the separation of Se species was studied. Complete separation was attained within 12min using a C8 column and a gradient performed with a mobile phase containing 0.1% (v/v) [C6mim]Cl at pH 6.0. The proposed method allows the separation of inorganic and organic Se species in a single chromatographic run, adding further benefits over already reported methods based on RP-HPLC. In addition, the influence of ILs on the AFS signals of each Se species was evaluated and a multivariate methodology was used for optimization of AFS sensitivity. The limits of detection were 0.92, 0.86, 1.41 and 1.19μgL(-1) for Se(IV), Se(VI), SeMet and SeMeSeCys, respectively. The method was successfully applied for speciation analysis of Se in complex samples, such as wine, beer, yeast and garlic.

  5. Generation of volatile copper species after in situ ionic liquid formation dispersive liquid-liquid microextraction prior to atomic absorption spectrometric detection.

    PubMed

    Stanisz, Ewa; Zgoła-Grześkowiak, Agnieszka; Matusiewicz, Henryk

    2014-11-01

    The new procedure using in situ synthesis of ionic liquid extractant for dispersive liquid-liquid microextraction (in situ IL DLLME) combined with generation of volatile species prior to electrothermal atomic absorption spectrometry (ET AAS) for the determination of copper in soil samples was developed. Analytical signals were obtained without the back-extraction of copper from the IL phase prior to its determination. Under optimal conditions, the extraction in 10 mL of sample solution employing 8 μL of 1-hexyl-3-methylimidazolium bis[(trifluoromethyl)sulfonyl]imide (HmimNTf2) (as the extraction solvent) was conducted. The ionic liquid served as two-task reagent: the efficient extractant and enhancement substance for generation step. The chemical generation of volatile species was performed by reduction of acidified copper solution (HCl 0.8 mol L(-1)) with NaBH4 (1.5%). Some essential parameters of the chemical generation such as NaBH4 and HCl concentrations, the kind and concentration of ionic liquid, carrier gas (Ar) flow rate, reaction and trapping time as well as pyrolysis and atomization temperatures were studied. For photogeneration the effect of the parameters such as the kind and concentration of low molecular weight organic acids and ionic liquid, carrier gas (Ar) flow rate, UV irradiation and ultrasonication time on the analytical signals were studied. The detection limit was found as 1.8 ng mL(-1) and the relative standard deviation (RSD) for seven replicate measurements of 100 µg mL(-1) in sample solution was 7%. The accuracy of the proposed method was evaluated by analysis of the certified reference materials. The measured copper contents in the reference materials were in satisfactory agreement with the certified values. The method was successfully applied to analysis of the soil and sediment samples.

  6. Intermolecular vibrations and fast relaxations in supercooled ionic liquids

    NASA Astrophysics Data System (ADS)

    Ribeiro, Mauro C. C.

    2011-06-01

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

  7. Viscosity Measurements on Ionic Liquids: A Cautionary Tale

    NASA Astrophysics Data System (ADS)

    Diogo, João C. F.; Caetano, Fernando J. P.; Fareleira, João M. N. A.; Wakeham, William A.

    2014-10-01

    The vibrating-wire viscometer has proven to be an exceedingly effective means of determining the viscosity of liquids over a wide range of temperature and pressure. The instrument has a long history but a variety of technological and theoretical developments over a number of years have improved its precision and most recently have enabled absolute measurements of high accuracy. However, the nature of the electrical measurements required for the technique has inhibited its widespread use for electrically conducting liquids so that there have been only a limited number of measurements. In the particular context of ionic liquids, which have themselves attracted considerable attention, this is unfortunate because it has meant that one primary measurement technique has seldom been employed for studies of their viscosity. In the last 2 years systematic efforts have been made to explore the applicability of the vibrating-wire technique by examining a number of liquids of increasing electrical conductivity. These extensions have been successful. However, in the process we have had cause to review previous studies of the viscosity and density of the same liquids at moderate temperatures and pressures and significant evidence has been accumulated to cause concern about the application of a range of viscometric techniques to these particular fluids. Because the situation is reminiscent of that encountered for a new set of environmentally friendly refrigerants at the end of the last decade, in this paper the experimental methods employed with these liquids have been reviewed which leads to recommendations for the handling of these materials that may have consequences beyond viscometric measurements. In the process new viscosity and density data for 1-hexyl-3-methylimidazolium bis[(trifluoromethyl)sulfonyl]imide [mim][], 1-ethyl-3-methylimidazolium ethyl sulfate [mim][], and 1-ethyl-3-methylpyridinium ethyl sulfate [mpy][] have been obtained.

  8. Surface effects on the structure and mobility of the ionic liquid C6C1ImTFSI in silica gels.

    PubMed

    Nayeri, Moheb; Aronson, Matthew T; Bernin, Diana; Chmelka, Bradley F; Martinelli, Anna

    2014-08-14

    We report on how the dynamical and structural properties of the ionic liquid 1-hexyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide (C6C1ImTFSI) change upon different degrees of confinement in silica gels. The apparent diffusion coefficients of the individual ions are measured by (1)H and (19)F pulsed field gradient nuclear magnetic resonance (PFG-NMR) spectroscopy, while the intermolecular interactions in the ionogels are elucidated by Raman spectroscopy. In addition, the local structure of the ionic liquid at the silica interface is probed by solid-state NMR spectroscopy. Importantly, we extend this study to a wider range of ionic liquid-to-silica molar ratios (x) than has been investigated previously, from very low (high degree of confinement) to very high (liquid-like gels) ionic liquid contents. Diffusion NMR measurements indicate that a solvation shell, with a significantly lower mobility than the bulk ionic liquid, forms at the silica interface. Additionally, the diffusion of the C6C1Im(+) and TFSI(-) ions decreases more rapidly below an observed molar ratio threshold (x < 1), with the intrinsic difference in the self-diffusion coefficient between the cation and anion becoming less pronounced. For ionic liquid molar ratio of x < 1, Raman spectroscopy reveals a different conformational equilibrium for the TFSI(-) anions compared to the bulk ionic liquid, with an increased population of the cisoid isomers with respect to the transoid. Concomitantly, at these high degrees of confinement the TFSI(-) anion experiences stronger ion-ion interactions as indicated by the evolution of the TFSI(-) characteristic vibrational mode at ∼740 cm(-1). Furthermore, solid-state 2D (29)Si{(1)H} HETCOR NMR measurements establish the interactions of the ionic liquid species with the silica surface, where the presence of adsorbed water results in weaker interactions between (29)Si surface moieties and the hydrophobic alkyl protons of the cationic C6C1Im(+) molecules.

  9. Application of response surface methodology for optimization of ionic liquid-based dispersive liquid-liquid microextraction of cadmium from water samples.

    PubMed

    Rajabi, M; Kamalabadi, M; Jamali, M R; Zolgharnein, J; Asanjarani, N

    2013-06-01

    A new, rapid, and simple method for the determination of cadmium in water samples was developed using ionic liquid-based dispersive liquid-liquid microextraction (IL-DLLME) coupled to flame atomic absorption spectrometry (FAAS). In the proposed approach, 2-(5-boromo-2-pyridylazo)-5-(diethyamino) phenol was used as a chelating agent and 1-hexyl-3-methylimidazolium bis(trifluoro methylsulfonyl)imide and acetone were selected as extraction and dispersive solvents, respectively. Sample pH, concentration of chelating agent, amount of ionic liquid (extraction solvent), disperser solvent volume, extraction time, salt effect, and centrifugation speed were selected as interested variables in IL-DLLME process. The significant variables affecting the extraction efficiency were determined using a Placket-Burman design. Thereafter, the significant variables were optimized using a Box-Behnken design and the quadratic model between the dependent and the independent variables was built. The optimum experimental conditions obtained from this statistical evaluation included: pH: 6.7; concentration of chelating agent: 1.1 10(-) (3) mol L(-1); and ionic liquid: 50.0 mg. Under the optimum conditions, the preconcentration factor obtained was 100. Calibration graph was linear in the range of 0.2-60 µg L(-1) with correlation coefficient of 0.9992. The limit of detection was 0.06 µg L(-) (1), which is lower than other reported approaches applied to the determination of cadmium using FAAS. The relative SD (n = 8) was 2.4%. The proposed method was successfully applied to the determination of trace amounts of cadmium in the real water samples with satisfactory results.

  10. Ionic liquid-based ultrasound-assisted dispersive liquid-liquid microextraction followed high-performance liquid chromatography for the determination of ultraviolet filters in environmental water samples.

    PubMed

    Zhang, Yufeng; Lee, Hian Kee

    2012-10-31

    In the present study, a rapid, highly efficient and environmentally friendly sample preparation method named ionic liquid-based ultrasound-assisted dispersive liquid-liquid microextraction (IL-USA-DLLME), followed by high performance liquid chromatography (HPLC) has been developed for the extraction and preconcentration of four benzophenone-type ultraviolet (UV) filters (viz. benzophenone (BP), 2-hydroxy-4-methoxybenzophenone (BP-3), ethylhexyl salicylate (EHS) and homosalate (HMS)) from three different water matrices. The procedure was based on a ternary solvent system containing tiny droplets of ionic liquid (IL) in the sample solution formed by dissolving an appropriate amount of the IL extraction solvent 1-hexyl-3-methylimidazolium tris(pentafluoroethyl)trifluorophosphate ([HMIM][FAP]) in a small amount of water-miscible dispersive solvent (methanol). An ultrasound-assisted process was applied to accelerate the formation of the fine cloudy solution, which markedly increased the extraction efficiency and reduced the equilibrium time. Various parameters that affected the extraction efficiency (such as type and volume of extraction and dispersive solvents, ionic strength, pH and extraction time) were evaluated. Under optimal conditions, the proposed method provided good enrichment factors in the range of 354-464, and good repeatability of the extractions (RSDs below 6.3%, n=5). The limits of detection were in the range of 0.2-5.0 ng mL(-1), depending on the analytes. The linearities were between 1 and 500 ng mL(-1) for BP, 5 and 500 ng mL(-1) for BP-3 and HMS and 10 and 500 ng mL(-1) for EHS. Finally, the proposed method was successfully applied to the determination of UV filters in river, swimming pool and tap water samples and acceptable relative recoveries over the range of 71.0-118.0% were obtained.

  11. Water-free rare-earth-metal ionic liquids/ionic liquid crystals based on hexanitratolanthanate(III) anion.

    PubMed

    Ji, Shun-Ping; Tang, Meng; He, Ling; Tao, Guo-Hong

    2013-04-02

    The hexanitratolanthanate anion (La(NO(3))(6)(3-)) is an interesting symmetric anion suitable to construct the component of water-free rare-earth-metal ionic liquids. The syntheses and structural characterization of eleven lanthanum nitrate complexes, [C(n)mim](3)[La(NO(3))(6)] (n=1, 2, 4, 6, 8, 12, 14, 16, 18), including 1,3-dimethylimidazolium hexanitratolanthanate ([C(1)mim](3)[La(NO(3))(6)], 1), 1-ethyl-3-methylimidazolium hexanitratolanthanate ([C(2)mim](3)[La(NO(3))(6)], 2), 1-butyl-3-methylimidazolium hexanitratolanthanate ([C(4)mim](3)[La(NO(3))(6)], 3), 1-isobutyl-3-methylimidazolium hexanetratolanthanate ([isoC(4)mim](3)[La(NO(3))(6)], 4), 1-methyl-3-(3'-methylbutyl)imidazolium hexanitratolanthanate ([MC(4)mim](3)[La(NO(3))(6)], 5), 1-hexyl-3-methylimidazolium hexanitratolanthanate ([C(6)mim](3)[La(NO(3))(6)], 6), 1-methyl-3-octylimidazolium hexanitratolanthanate ([C(8)mim](3)[La(NO(3))(6)], 7), 1-dodecyl-3-methylimidazolium hexanitratolanthanate ([C(12)mim](3)[La(NO(3))(6)], 8), 1-methyl-3-tetradecylimidazolium hexanitratolanthanate ([C(14)mim](3)[La-(NO(3))(6)], 9), 1-hexadecyl-3-methylimid-azolium hexanitratolanthanum ([C(16)dmim](3)[La(NO(3))(6)], 10), and 1-methyl-3-octadecylimidazolium hexanitratolanthanate ([C(18)mim](3)[La(NO(3))(6)], 11) are reported. All new compounds were characterized by (1)H and (13)C NMR, and IR spectroscopy as well as elemental analysis. The crystal structure of compound 1 was determined by using single-crystal X-ray diffraction, giving the following crystallographic information: monoclinic; P2(1)/c; a=15.3170 (3), b=14.2340 (2), c=13.8954(2) Å; β=94.3453(15)°, V=3020.80(9) Å(3), Z=4, ρ=1.764 g cm(-3). The coordination polyhedron around the lanthanum ion is rationalized by six nitrate anions with twelve oxygen atoms. No hydrogen-bonding network or water molecule was found in 1. The thermodynamic stability of the new complexes was investigated by using thermogravimetric analysis (TGA). The water

  12. Excess enthalpy of monoethanolamine + ionic liquid mixtures: how good are COSMO-RS predictions?

    PubMed

    Gonzalez-Miquel, Maria; Massel, Marjorie; DeSilva, Aruni; Palomar, Jose; Rodriguez, Francisco; Brennecke, Joan F

    2014-10-02

    Mixtures of ionic liquids (ILs) and molecular amines have been suggested for CO2 capture applications. The basic idea is to replace water, which volatilizes in the amine regeneration step and increases the parasitic energy load, with a nonvolatile ionic liquid solvent. To fully understand the thermodynamics of these systems, here experimental excess enthalpies for binary mixtures of monoethanolamine (MEA) and two ILs: 1-hexyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide, [hmim][NTf2], and 1-(2-hydroxyethyl)-3-methylimidazolium bis(trifluoromethylsulfonyl)imide, [OHemim][NTf2], were obtained by calorimetry, using a Setaram C80 calorimeter, over the whole range of compositions at 313.15 K. Since it is the temperature derivative of the Gibbs energy, enthalpy is a sensitive measure of intermolecular interactions. MEA + [hmim][NTf2] is endothermic and MEA + [OHemim][NTf2] is exothermic. The reliability of COSMO-RS to predict the excess enthalpy of the (MEA+IL) systems was tested based on the implementation of two different molecular models to define the structure of the IL: the IL as separate cation and anion [C+A] and the IL as a bonded single specie [CA]. Quantum-chemical calculations were performed to gain additional insight into the intermolecular interactions between the components of the mixture. For MEA + [hmim][NTf2] both the [C+A] and [CA] models predict endothermic behavior, but the [CA] model is in better agreement with the experimental results. For MEA + [OHemim][NTf2] the [C+A] model provides the best match to the experimental exothermic results. However, what is really surprising is that two different conformations of the cation-anion pair with nearly identical energies in the [CA] model result in completely different (exothermic vs endothermic) predictions of the excess enthalpy. Nonetheless, the results do show that the influence of the structure of the IL on the thermodynamic behavior of the mixture (endothermic vs exothermic) can be attributed

  13. Interaction of ionic liquid with water with variation of water content in 1-butyl-3-methyl-imidazolium hexafluorophosphate ([bmim][PF6])/TX-100/water ternary microemulsions monitored by solvent and rotational relaxation of coumarin 153 and coumarin 490.

    PubMed

    Seth, Debabrata; Chakraborty, Anjan; Setua, Palash; Sarkar, Nilmoni

    2007-06-14

    The interaction of water with room temperature ionic liquid (RTIL) [bmim][PF6] has been studied in [bmim][PF6]/TX-100/water ternary microemulsions by solvent and rotational relaxation of coumarin 153 (C-153) and coumarin 490 (C-490). The rotational relaxation and average solvation time of C-153 and C-490 gradually decrease with increase in water content of the microemulsions. The gradual increase in the size of the microemulsion with increase in w0 (w0=[water]/[surfactant]) is evident from dynamic light scattering measurements. Consequently the mobility of the water molecules also increases. In comparison to pure water the retardation of solvation time in the RTIL containing ternary microemulsions is very less. The authors have also reported the solvation time of C-490 in neat [bmim][PF6]. The solvation time of C-490 in neat [bmim][PF6] is bimodal with time constants of 400 ps and 1.10 ns.

  14. Interaction of ionic liquid with water with variation of water content in 1-butyl-3-methyl-imidazolium hexafluorophosphate ([bmim][PF6])/TX-100/water ternary microemulsions monitored by solvent and rotational relaxation of coumarin 153 and coumarin 490

    NASA Astrophysics Data System (ADS)

    Seth, Debabrata; Chakraborty, Anjan; Setua, Palash; Sarkar, Nilmoni

    2007-06-01

    The interaction of water with room temperature ionic liquid (RTIL) [bmim][PF6] has been studied in [bmim][PF6]/TX-100/water ternary microemulsions by solvent and rotational relaxation of coumarin 153 (C-153) and coumarin 490 (C-490). The rotational relaxation and average solvation time of C-153 and C-490 gradually decrease with increase in water content of the microemulsions. The gradual increase in the size of the microemulsion with increase in w0 (w0=[water]/[surfactant]) is evident from dynamic light scattering measurements. Consequently the mobility of the water molecules also increases. In comparison to pure water the retardation of solvation time in the RTIL containing ternary microemulsions is very less. The authors have also reported the solvation time of C-490 in neat [bmim][PF6]. The solvation time of C-490 in neat [bmim][PF6] is bimodal with time constants of 400ps and 1.10ns.

  15. {2,6-Bis[(2,6-diisopropyl-phosphan-yl)-oxy]-4-fluoro-phenyl-κ(3)P,C(1),P'}(1H-pyrazole-κN(2))nickel(II) hexa-fluoro-phosphate.

    PubMed

    Kwan, Man-Lung; Conry, Sara J; Carfagna, Charles S; Press, Loren P; Ozerov, Oleg V; Hoffman, Norris W; Sykora, Richard E

    2012-10-01

    The title compound, [Ni(C(18)H(30)FO(2)P(2))(C(3)H(4)N(2))]PF(6), was prepared by halide abstraction with TlPF(6) in the presence of CH(3)CN in CDCl(3) from the respective neutral pincer chlorido analogue followed by addition of pyrazole. The PO-C-OP pincer ligand acts in typical trans-P(2) tridentate fashion to generate a distorted square-planar nickel structure. The Ni-N(pyrazole) distance is 1.925 (2) Å and the plane of the pyrazole ligand is rotated 56.2 (1)° relative to the approximate square plane surrounding the Ni(II) center in which the pyrazole is bound to the Ni(II) atom through its sp(2)-hybridized N atom. This Ni-N distance is similar to bond lengths in the other reported Ni(II) pincer-ligand square-planar pyrazole complex structures; however, its dihedral angle is significantly larger than any of those for the latter set of pyrazole complexes.

  16. trans-Diaqua{5,5'-[(E,E)-pyridine-2,6-diylbis(methylidynenitrilo)]bis[pyrimidine-2,4(1H,3H)-dione]}zinc(II) nitrate hexafluorophosphate trihydrate.

    PubMed

    Ozdemir, Namik; Dinçer, Muharrem; Doğaner, Gamze; Astley, Demet; Astley, Stephen T

    2007-04-01

    The title compound, [Zn(C(15)H(11)N(7)O(4))(H(2)O)(2)](NO(3))(PF(6)).3H(2)O, contains a mononuclear zinc(II) complex. The Zn(2+) centre is seven-coordinated in a slightly distorted pentagonal-bipyramidal geometry, with the two water O atoms located in the apical positions, and the pyridine N atom, the two imine N atoms and two carbonyl O atoms of the uracil groups located in the equatorial plane. The charge is balanced by PF(6)(-) and NO(3)(-) anions.

  17. Ionic Liquid Membranes for Carbon Dioxide Separation

    SciTech Connect

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

    2008-07-12

    Recent scientific studies are rapidly advancing novel technological improvements and engineering developments that demonstrate the ability to minimize, eliminate, or facilitate the removal of various contaminants and green house gas emissions in power generation. The Integrated Gasification Combined Cycle (IGCC) shows promise for carbon dioxide mitigation not only because of its higher efficiency as compared to conventional coal firing plants, but also due to a higher driving force in the form of high partial pressure. One of the novel technological concepts currently being developed and investigated is membranes for carbon dioxide (CO2) separation, due to simplicity and ease of scaling. A challenge in using membranes for CO2 capture in IGCC is the possibility of failure at elevated temperatures or pressures. Our earlier research studies examined the use of ionic liquids on various supports for CO2 separation over the temperature range, 37°C-300°C. The ionic liquid, 1-hexyl-3methylimidazolium Bis(trifluoromethylsulfonyl)imide, ([hmim][Tf2N]), was chosen for our initial studies with the following supports: polysulfone (PSF), poly(ether sulfone) (PES), and cross-linked nylon. The PSF and PES supports had similar performance at room temperature, but increasing temperature caused the supported membranes to fail. The ionic liquid with the PES support greatly affected the glass transition temperature, while with the PSF, the glass transition temperature was only slightly depressed. The cross-linked nylon support maintained performance without degradation over the temperature range 37-300°C with respect to its permeability and selectivity. However, while the cross-linked nylon support was able to withstand temperatures, the permeability continued to increase and the selectivity decreased with increasing temperature. Our studies indicated that further testing should examine the use of other ionic liquids, including those that form chemical complexes with CO2 based on

  18. Liquid clathrate formation in ionic liquid-aromatic mixtures.

    PubMed

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

    2003-02-21

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

  19. The effect of C2 substitution on melting point and liquid phase dynamics of imidazolium based-ionic liquids: insights from molecular dynamics simulations

    SciTech Connect

    Zhang, Y; Maginn, EJ

    2012-01-01

    Using molecular dynamics simulations, the melting points and liquid phase dynamic properties were studied for four alkyl-imidazolium-based ionic liquids, 1-n-butyl-3-methylimidazolium hexafluorophosphate ([BMIM][PF6]), 1-n-butyl-2,3-dimethylimidazolium hexafluorophosphate ([BMMIM][PF6]), 1-ethyl-3-methylimidazolium hexafluorophosphate ([EMIM][PF6]), and 1-ethyl-2,3-dimethylimidazolium hexafluorophosphate ([EMMIM][PF6]), respectively. Experimentally it has been observed that the substitution of a methyl group for a hydrogen at the C2 position of the cation ring leads to an increase in both the melting point and liquid phase viscosity, contrary to arguments that had been made regarding associations between the ions. The melting points of the four ionic liquids were accurately predicted using simulations, as were the trends in viscosity. The simulation results show that the origin of the effect is mainly entropic, although enthalpy also plays an important role.

  20. Novel microemulsions: ionic liquid-in-ionic liquid.

    PubMed

    Cheng, Siqing; Zhang, Jianling; Zhang, Zhaofu; Han, Buxing

    2007-06-28

    The hydrophobic IL 1-butyl-3-methylimidazolium hexafluorophosphate ([bmim][PF(6)]) can be dispersed in hydrophilic IL propylammonium formate (PAF) with the aid of surfactant AOT, and [bmim][PF(6)]-in-PAF microemulsions are formed.

  1. Participation in CAPPS/IUCRC

    DTIC Science & Technology

    2013-04-17

    upon reaction with peroxyl radicals. Oxygen sensitive fluorescent dye tris (4,7-diphenyl-1,10- phenanthroline) ruthenium bis (hexafluorophosphate...distribution of SLN and NLC particles containing ruthenium based oxygen sensitive dye was also measured using DLS. Based on these measurements, the...canola oil, tris (4,7-diphenyl-1,10- phenanthroline) ruthenium (II) bis (hexafluorophosphate) complex for measuring oxygen transport across nanoparticle or

  2. Operationally Simple Synthesis of N,N-Diethyl-3-Methylbenzamide (DEET) Using COMU as a Coupling Reagent

    ERIC Educational Resources Information Center

    Withey, Jonathan M.; Bajic, Andrea

    2015-01-01

    A novel procedure is described where students use COMU [(1-cyano-2-ethoxy-2-oxoethylidenaminooxy)dimethylamino-morpholino-carbenium hexafluorophosphate], as a nonhazardous partner, in the one-pot coupling of a carboxylic acid and amine producing N,N-diethyl-3-methylbenzamide (DEET). Fundamental principles of carbonyl reactivity are understood,…

  3. Surfactant solvation effects and micelle formation in ionic liquids.

    PubMed

    Anderson, Jared L; Pino, Verónica; Hagberg, Erik C; Sheares, Valerie V; Armstrong, Daniel W

    2003-10-07

    The formation of micelles in 1-butyl-3-methyl imidazolium chloride (BMIM-Cl) and hexafluorophosphate (BMIM-PF6) were explored using different surfactants and the solvation behavior of the new micellar-ionic liquid solutions examined using inverse gas chromatography.

  4. Vibrational Spectroscopic Study of Imidazolium Dicationic Ionic Liquids: Effect of Cation Alkyl Chain Length

    NASA Astrophysics Data System (ADS)

    Moumene, T.; Belarbi, E. H.; Haddad, B.; Villemin, D.; Abbas, O.; Khelifa, B.; Bresson, S.

    2016-05-01

    Two new dicationic ionic liquids were synthesized: bis-methyl imidazolium methylidene hexafluorophosphate [M(CH2)IM2 +][2PF 6 - ] and bis-methyl imidazolium propylidene hexafluorophosphate [M(CH2)3IM2 +][2PF 6 - ]. Their structures were identified by H, C, P, F NMR, FTIR/ATR, and FT-Raman spectroscopies in order to study the effect of cation alkyl chain length on vibration behaviors. Several changes were recorded, which were related to alkyl chain length. A frequency shift was observed in some modes while others remained insensitive. A greater number of peaks was found in the FTIR/ATR spectra and the FT-Raman spectra with increasing alkyl chain length, which indicated that chain length influences the N-C connection twisting. More peaks with strong intensity appeared for longer alkyl chain lengths.

  5. Photonics of a conjugated organometallic Pt-Ir polymer and its model compounds exhibiting hybrid CT excited states.

    PubMed

    Soliman, Ahmed M; Fortin, Daniel; Zysman-Colman, Eli; Harvey, Pierre D

    2012-04-13

    Trans- dichlorobis(tri-n-butylphosphine)platinum(II) reacts with bis(2- phenylpyridinato)-(5,5'-diethynyl-2,2'-bipyridine)iridium(III) hexafluorophosphate to form the luminescent conjugated polymer poly[trans-[(5,5'-ethynyl-2,2'-bipyridine)bis(2- phenylpyridinato)-iridium(III)]bis(tri-n-butylphosphine)platinum(II)] hexafluorophosphate ([Pt]-[Ir])n. Gel permeation chromatography indicates a degree of polymerization of 9 inferring the presence of an oligomer. Comparison of the absorption and emission band positions and their temperature dependence, emission quantum yields, and lifetimes with those for models containing only the [Pt] or the [Ir] units indicates hybrid excited states including features from both chromophores.

  6. Surface segregation in binary mixtures of imidazolium-based ionic liquids

    NASA Astrophysics Data System (ADS)

    Souda, Ryutaro

    2010-09-01

    Surface composition of binary mixtures of room-temperature ionic liquids has been investigated using time-of-flight secondary ion mass spectrometry at room temperature over a wide composition range. The imidazolium cations with longer aliphatic groups tend to segregate to the surface, and a bis(trifluoromethanesulfonyl)imide anion (Tf 2N -) is enriched at the surface relative to hexafluorophosphate (PF 6-). The surface of an equimolar mixture of Li[Tf 2N] and 1-butyl-3-methylimidazolium hexafluorophosphate ([bmim][PF 6]) has a nominal composition of [bmim][Tf 2N] because of surface segregation and ligand exchange. The surface segregation of cations and anions is likely to result from alignment of specific ligand-exchanged molecules at the topmost surface layer to exclude more hydrophobic part of the molecules.

  7. Amide and Peptide Bond Formation in Water at Room Temperature.

    PubMed

    Gabriel, Christopher M; Keener, Megan; Gallou, Fabrice; Lipshutz, Bruce H

    2015-08-21

    A general and environmentally responsible method for the formation of amide/peptide bonds in an aqueous micellar medium is described. Use of uronium salt (1-cyano-2-ethoxy-2-oxoethylidenaminooxy)dimethylaminomorpholinocarbenium hexafluorophosphate (COMU) as a coupling reagent, 2,6-lutidine, and TPGS-750-M represents mild conditions associated with these valuable types of couplings. The aqueous reaction medium is recyclable leading to low E Factors.

  8. Performance Loss of Lithium Ion Polymer Batteries Subjected to Overcharge and Overdischarge Abuse

    DTIC Science & Technology

    2012-11-16

    hexafluorophosphate EC: ethylene carbonate DEC: diethyl carbonate DMC: dimethyl carbonate PC: propylene carbonate     2    2. Introduction  Lithium -ion...Naval Research Laboratory Washington, DC 20375-5320 NRL/MR/6110--12-9455 Performance Loss of Lithium Ion Polymer Batteries Subjected to Overcharge...ABSTRACT c. THIS PAGE 18. NUMBER OF PAGES 17. LIMITATION OF ABSTRACT Performance Loss of Lithium Ion Polymer Batteries Subjected to Overcharge and

  9. Photointercalating Semiconductor/Solid Electrolyte Junctions for Storage and Chemical Detection. Phase 2.

    DTIC Science & Technology

    1988-05-31

    Typical thermal gradients used were between 750C and 8000 C. Crystal growth occurred over 25 days. In all 4cases the relatively large crystals obtained...mixture together with 5mg 12/ml of the quartz transport tube volume. This was performed in a three temperature zone furnace. Typical thermal gradients...character- isti, s of single crystal n-HfS 2 in liquid non-aqueous electrolyte (acetonitrile containing O.1M tetrabutylammonium hexafluorophosphate

  10. Magnetic solid phase extraction using ionic liquid-coated core-shell magnetic nanoparticles followed by high-performance liquid chromatography for determination of Rhodamine B in food samples.

    PubMed

    Chen, Jieping; Zhu, Xiashi

    2016-06-01

    Three hydrophobic ionic liquids (ILs) (1-butyl-3-methylimidazole hexafluorophosphate ([BMIM]PF6), 1-hexyl-3-methyl-imidazole hexafluoro-phosphate ([HMIM]PF6), and 1-octyl-3-methylimidazole hexafluorophosphate ([OMIM]PF6)) were used to coat Fe3O4@SiO2 nanoparticles (NPs) with core-shell structures to prepare magnetic solid phase extraction (MSPE) agents (Fe3O4@SiO2@IL). A novel method of MSPE coupled with high-performance liquid chromatography for the separation/analysis of Rhodamine B was then established. The results showed that Rhodamine B was adsorbed rapidly on Fe3O4@SiO2@[OMIM]PF6 and was released using ethanol. Under optimal conditions, the pre-concentration factor for the proposed method was 25. The linear range, limit of detection (LOD), correlation coefficient (R), and relative standard deviation (RSD) were found to be 0.50-150.00 μgL(-1), 0.08 μgL(-1), 0.9999, and 0.51% (n=3, c=10.00 μgL(-1)), respectively. The Fe3O4@SiO2 NPs could be re-used up to 10 times. The method was successfully applied to the determination of Rhodamine B in food samples.

  11. Why Is CO2 so soluble in imidazolium-based ionic liquids?

    PubMed

    Cadena, Cesar; Anthony, Jennifer L; Shah, Jindal K; Morrow, Timothy I; Brennecke, Joan F; Maginn, Edward J

    2004-04-28

    Experimental and molecular modeling studies are conducted to investigate the underlying mechanisms for the high solubility of CO2 in imidazolium-based ionic liquids. CO2 absorption isotherms at 10, 25, and 50 degrees C are reported for six different ionic liquids formed by pairing three different anions with two cations that differ only in the nature of the "acidic" site at the 2-position on the imidazolium ring. Molecular dynamics simulations of these two cations paired with hexafluorophosphate in the pure state and mixed with CO2 are also described. Both the experimental and the simulation results indicate that the anion has the greatest impact on the solubility of CO2. Experimentally, it is found that the bis(trifluoromethylsulfonyl)imide anion has the greatest affinity for CO2, while there is little difference in CO2 solubility between ionic liquids having the tetrafluoroborate or hexafluorophosphate anion. The simulations show strong organization of CO2 about hexafluorophosphate anions, but only small differences in CO2 structure about the different cations. This is consistent with the experimental finding that, for a given anion, there are only small differences in CO2 solubility for the two cations. Computed and measured densities, partial molar volumes, and thermal expansion coefficients are also reported.

  12. Ionic liquid coated magnetic core/shell Fe3O4@SiO2 nanoparticles for the separation/analysis of linuron in food samples

    NASA Astrophysics Data System (ADS)

    Chen, Jieping; Zhu, Xiashi

    2015-02-01

    Three hydrophobic ionic liquids (ILs) including 1-butyl-3-methylimidazole hexafluorophosphate ([BMIM]PF6), 1-hexyl-3-methyl-imidazole hexafluorophosphate ([HMIM]PF6), and 1-octyl-3-methylimidazole hexafluoro-phosphate ([OMIM]PF6) coated Fe3O4@SiO2 nanoparticles with core-shell structure to prepare magnetic solid phase extraction agent (Fe3O4@SiO2@ILs) and establish a new method of magnetic solid phase extraction (MSPE) coupled with UV spectrometry for separation/analysis of linuron. The results showed that linuron was adsorbed rapidly by Fe3O4@SiO2@[OMIM]PF6 and eluanted by ethanol. Under the optimal conditions, preconcentration factor of the proposed method was 10-fold. The linear range, detection limit, correlation coefficient (R) and relative standard deviation (RSD) were found to be 0.04-20.00 μg mL-1, 5.0 ng mL-1, 0.9993 and 2.8% (n = 3, c = 4.00 μg mL-1), respectively. The Fe3O4@SiO2 nanoparticles could be used repeatedly for 10 times. This proposed method has been successfully applied to the determination of linuron in food samples.

  13. Stereoselective Alkane Oxidation with meta-Chloroperoxybenzoic Acid (MCPBA) Catalyzed by Organometallic Cobalt Complexes.

    PubMed

    Shul'pin, Georgiy B; Loginov, Dmitriy A; Shul'pina, Lidia S; Ikonnikov, Nikolay S; Idrisov, Vladislav O; Vinogradov, Mikhail M; Osipov, Sergey N; Nelyubina, Yulia V; Tyubaeva, Polina M

    2016-11-22

    Cobalt pi-complexes, previously described in the literature and specially synthesized and characterized in this work, were used as catalysts in homogeneous oxidation of organic compounds with peroxides. These complexes contain pi-butadienyl and pi-cyclopentadienyl ligands: [(tetramethylcyclobutadiene)(benzene)cobalt] hexafluorophosphate, [(C₄Me₄)Co(C₆H₆)]PF₆ (1); diiodo(carbonyl)(pentamethylcyclopentadienyl)cobalt, Cp*Co(CO)I₂ (2); diiodo(carbonyl)(cyclopentadienyl)cobalt, CpCo(CO)I₂ (3); (tetramethylcyclobutadiene)(dicarbonyl)(iodo)cobalt, (C₄Me₄)Co(CO)₂I (4); [(tetramethylcyclobutadiene)(acetonitrile)(2,2'-bipyridyl)cobalt] hexafluorophosphate, [(C₄Me₄)Co(bipy)(MeCN)]PF₆ (5); bis[dicarbonyl(B-cyclohexylborole)]cobalt, [(C₄H₄BCy)Co(CO)₂]₂ (6); [(pentamethylcyclopentadienyl)(iodo)(1,10-phenanthroline)cobalt] hexafluorophosphate, [Cp*Co(phen)I]PF₆ (7); diiodo(cyclopentadienyl)cobalt, [CpCoI₂]₂ (8); [(cyclopentadienyl)(iodo)(2,2'-bipyridyl)cobalt] hexafluorophosphate, [CpCo(bipy)I]PF₆ (9); and [(pentamethylcyclopentadienyl)(iodo)(2,2'-bipyridyl)cobalt] hexafluorophosphate, [Cp*Co(bipy)I]PF₆ (10). Complexes 1 and 2 catalyze very efficient and stereoselective oxygenation of tertiary C-H bonds in isomeric dimethylcyclohexanes with MCBA: cyclohexanols are produced in 39 and 53% yields and with the trans/cis ratio (of isomers with mutual trans- or cis-configuration of two methyl groups) 0.05 and 0.06, respectively. Addition of nitric acid as co-catalyst dramatically enhances both the yield of oxygenates and stereoselectivity parameter. In contrast to compounds 1 and 2, complexes 9 and 10 turned out to be very poor catalysts (the yields of oxygenates in the reaction with cis-1,2-dimethylcyclohexane were only 5%-7% and trans/cis ratio 0.8 indicated that the oxidation is not stereoselective). The chromatograms of the reaction mixture obtained before and after reduction with PPh₃ are very similar, which testifies that alkyl

  14. Synthesis and Photophysical and Electrochemical Properties of Functionalized Mono-, Bis-, and Trisanthracenyl Bridged Ru(II) Bis(2,2′:6′,2″-terpyridine) Charge Transfer Complexes

    PubMed Central

    Adeloye, Adewale O.; Ajibade, Peter A.

    2014-01-01

    With the aim of developing new molecular devices having long-range electron transfer in artificial systems and as photosensitizers, a series of homoleptic ruthenium(II) bisterpyridine complexes bearing one to three anthracenyl units sandwiched between terpyridine and 2-methyl-2-butenoic acid group are synthesized and characterized. The complexes formulated as bis-4′-(9-monoanthracenyl-10-(2-methyl-2-butenoic acid) terpyridyl) ruthenium(II) bis(hexafluorophosphate) (RBT1), bis-4′-(9-dianthracenyl-10-(2-methyl-2-butenoic acid) terpyridyl) ruthenium(II) bis(hexafluorophosphate) (RBT2), and bis-4′-(9-trianthracenyl-10-(2-methyl-2-butenoic acid) terpyridyl) ruthenium(II) bis(hexafluorophosphate) (RBT3) were characterized by elemental analysis, FT-IR, UV-Vis, photoluminescence, 1H and 13C NMR spectroscopy, and electrochemical techniques by elemental analysis, FT-IR, UV-Vis, photoluminescence, 1H and 13C NMR spectroscopy, and electrochemical techniques. The cyclic voltammograms (CVs) of (RBT1), (RBT2), and (RBT3) display reversible one-electron oxidation processes at E1/2 = 1.13 V, 0.71 V, and 0.99 V, respectively (versus Ag/AgCl). Based on a general linear correlation between increase in the length of π-conjugation bond and the molar extinction coefficients, the Ru(II) bisterpyridyl complexes show characteristic broad and intense metal-to-ligand charge transfer (MLCT) band absorption transitions between 480–600 nm, ε = 9.45 × 103 M−1 cm−1, and appreciable photoluminescence spanning the visible region. PMID:24883408

  15. Partition coefficients of organic compounds in new imidazolium based ionic liquids using inverse gas chromatography.

    PubMed

    Revelli, Anne-Laure; Mutelet, Fabrice; Jaubert, Jean-Noël

    2009-06-05

    Partition coefficients of organic compounds in four ionic liquids: 1-ethanol-3-methylimidazolium tetrafluoroborate, 1-ethanol-3-methylimidazolium hexafluorophosphate, 1,3-dimethylimidazolium dimethylphosphate and 1-ethyl-3-methylimidazolium diethylphosphate were measured using inverse gas chromatography from 303.3 to 332.55K. The influence of gas-liquid and gas-solid interfacial adsorption of different solutes on ionic liquids was also studied. Most of the polar solutes were retained largely by partition while light hydrocarbons were retained predominantly by interfacial adsorption on the ionic liquids studied in this work. The solvation characteristics of the ionic liquids were evaluated using the Abraham solvation parameter model.

  16. Silver(I) complexes of mono- and bidentate N-heterocyclic carbene ligands: synthesis, crystal structures, and in vitro antibacterial and anticancer studies.

    PubMed

    Haque, Rosenani A; Choo, Sze Yii; Budagumpi, Srinivasa; Iqbal, Muhammad Adnan; Al-Ashraf Abdullah, Amirul

    2015-01-27

    A series of benzimidazole-based N-heterocyclic carbene (NHC) proligands {1-benzyl-3-(2-methylbenzyl)-benzimidazolium bromide/hexafluorophosphate (1/4), 1,3-bis(2-methylbenzyl)-benzimidazolium bromide/hexafluorophosphate (2/5) and 1,3-bis(3-(2-methylbenzyl)-benzimidazolium-1-ylmethylbenzene dibromide/dihexafluorophosphate (3/6)} has been synthesized by the successive N-alkylation method. Ag complexes {1-benzyl-3-(2-methylbenzyl)-benzimidazol-2-ylidenesilver(I) hexafluorophosphate (7), 1,3-bis(2-methylbenzyl)-benzimidazol-2-ylidenesilver(I) hexafluorophosphate (8) and 1,3-bis(3-(2-methylbenzyl)-benzimidazol-2-ylidene)-1-ylmethylbenzene disilver(I) dihexafluorophosphate (9)} of NHC ligands have been synthesized by the treatment of benzimidazolium salts with Ag2O at mild reaction conditions. Both, NHC proligands and Ag-NHC complexes have been characterized by (1)H and (13)C{(1)H} NMR and FTIR spectroscopy and elemental analysis technique. Additionally, the structure of the NHC proligand 5 and the mononuclear Ag complexes 7 and 8 has been elucidated by the single crystal X-ray diffraction analysis. Both the complexes exhibit the same general structural motif with linear coordination geometry around the Ag centre having two NHC ligands. Preliminary in vitro antibacterial potentials of reported compounds against a Gram negative (Escherichia coli) and a Gram positive (Bacillus subtilis) bacteria evidenced the higher activity of mononuclear silver(I) complexes. The anticancer studies against the human derived colorectal cancer (HCT 116) and colorectal adenocarcinoma (HT29) cell lines using the MTT assay method, revealed the higher activity of Ag-NHC complexes. The benzimidazolium salts 4-6 and Ag-NHC complexes 7-9 displayed the following IC50 values against the HCT 116 and HT29 cell lines, respectively, 31.8 ± 1.9, 15.2 ± 1.5, 4.8 ± 0.6, 10.5 ± 1.0, 18.7 ± 1.6, 1.20 ± 0.3 and 245.0 ± 4.6, 8.7 ± 0.8, 146.1 ± 3.1, 7.6 ± 0.7, 5.5 ± 0.8, 103.0 ± 2.3 μM.

  17. Multi-scale modelling of supercapacitors: From molecular simulations to a transmission line model

    NASA Astrophysics Data System (ADS)

    Pean, C.; Rotenberg, B.; Simon, P.; Salanne, M.

    2016-09-01

    We perform molecular dynamics simulations of a typical nanoporous-carbon based supercapacitor. The organic electrolyte consists in 1-ethyl-3-methylimidazolium and hexafluorophosphate ions dissolved in acetonitrile. We simulate systems at equilibrium, for various applied voltages. This allows us to determine the relevant thermodynamic (capacitance) and transport (in-pore resistivities) properties. These quantities are then injected in a transmission line model for testing its ability to predict the charging properties of the device. The results from this macroscopic model are in good agreement with non-equilibrium molecular dynamics simulations, which validates its use for interpreting electrochemical impedance experiments.

  18. A study of the time-resolved fluorescence spectrum and red edge effect of ANF in a room-temperature ionic liquid.

    PubMed

    Hu, Zhonghan; Margulis, Claudio J

    2006-06-15

    In a recent article, we have analyzed using molecular dynamics simulations the steady-state red edge effect (REE) observed by Samanta and co-workers when the fluorescent probe 2-amino-7-nitrofluorene (ANF) is photoexcited at different wavelengths in 1-butyl-3-methylimidazolium ([BMIM+]) hexafluorophosphate ([PF6-]). In this letter, we predict the time- and wavelength-dependent emission spectra of ANF in the same ionic solvent. From the analysis of our simulated data, we are able to derive an approximate time scale for reorganization of the solvent around the solute probe. The effect that slow varying local liquid environments have on the overall time-dependent signal is also discussed.

  19. Electrochemical determination of hydroquinone using hydrophobic ionic liquid-type carbon paste electrodes

    PubMed Central

    2010-01-01

    Three types of carbon paste electrodes (CPEs) with different liquid binders were fabricated, and their electrochemical behavior was characterized via a potassium hexacyanoferrate(II) probe. 1-Octyl-3-methylimidazolium hexafluorophosphate ionic liquid (IL) as a hydrophobic conductive pasting binder showed better electrochemical performance compared with the commonly employed binder. The IL-contained CPEs demonstrated excellent electroactivity for oxidation of hydroquinone. A diffusion control mechanism was confirmed and the diffusion coefficient (D) of 5.05 × 10-4 cm2 s-1 was obtained. The hydrophobic IL-CPE is promising for the determination of hydroquinone in terms of high sensitivity, easy operation, and good durability. PMID:20977733

  20. Triply-Bridged Diboron Species of the Pyrazabole Type.

    DTIC Science & Technology

    1985-07-01

    100 mL of a 0.2 M solution of 5 ethylboryl ditosylate in toluene was refluxed with stirring for 3 h. After cooling to room temperature, the solid...03SC6H4 -4-CH 3 ), with pz ion and was isolated as the 5hexafluorophosphate salt; no experimental details were given. The structure 1 5 1 of the...OTs or S 3 SCF3 = OTf) in 3 :2 molar ratio, the desired cation [C 2HsB(p-pz) 3 BC2H + 5 1 was obtained in about 20 (X = OTs) or 40 (X = OTf) % yield

  1. Targeting PCNA Phosphorylation in Breast Cancer

    DTIC Science & Technology

    2011-04-01

    Ninhydrin test (Kaiser’s test ; described below). A solution of 2.1 ml 0.45M O-Benzotriazole-N,N,N’,N’-tetramethyl-uronium- hexafluoro-phosphate (HBTU...Residue coupling is confirmed via a Ninhydrin test . The deprotection and coupling steps are repeated until the entire peptide has been synthesized...and the remaining residue is dissolved in acetonitrile/water (1:1). Ninhydrin (Kaiser’s) Test Solutions used:  5g ninhydrin in 100ml ethanol

  2. Development of Bitter Taste Sensor Using Ionic-Liquid/Polymer Membranes

    NASA Astrophysics Data System (ADS)

    Akutagawa, Nobuyuki; Toida, Jinichi; Amano, Yoshihiko; Ikezaki, Hidekazu; Toko, Kiyoshi; Arikawa, Yukihiko

    A taste sensor is composed of several kinds of lipid/polymer membranes as transducers which convert taste information to electric signal. Thus, the role of membranes is very important to detect various taste components. In this paper, we developed novel membranes which specifically respond to quinine that is typical bitter substances. These membranes were composed of hydrophobic ionic liquid such as N, N, N-trimethyl-N-propylammonium bis(trifluoromethansulfonyl)imide, 1-butyl-3-methylimidazolium hexafluorophosphate and 1-butylpyridinium hexafluorophosphate, a plasticizer, 2-nitrophenyl octyl ether and a polymer, polyvinyl chloride. In addition to quinine, they also showed response to both several kinds of alkaloids such as caffeine and strychnine, and non-alkaloid such as phenylthiocarbamide. The order of these responses was equal to that of the tongue glossopharyngeal nerve of flog. Furthermore, there were the other alkaloids which response to these membranes. Especially in these alkaloids, they showed high response to denatonium benzoate and berberin chloride which have a strong bitter taste.

  3. Ionic liquid-linked dual magnetic microextraction of lead(II) from environmental samples prior to its micro-sampling flame atomic absorption spectrometric determination.

    PubMed

    Yilmaz, Erkan; Soylak, Mustafa

    2013-11-15

    A novel and rapid microextraction approach termed as ionic liquid-linked dual magnetic microextraction (IL-DMME), was developed for the atomic absorption spectrometric determination of lead. The developed method based on a combination of dispersive liquid-liquid microextraction (DLLME) and dispersive micro solid-phase extraction (D-μ-SPE). In the first DLLME step, 1-butyl-3-methylimidazolium hexafluorophosphate [C4mim][PF6], was selected to extract the lead-pyrrolidine-dithiocarbamate (Pb-PDC) complex from sample solution by the assistance of vortex agitator. After the first step, fifty milligrams of Fe3O4 magnetic nanoparticles (MNPs) were added to extraction of the ionic liquid and Pb-PDC complex in aqueous solution. The effective factors in proposed IL-DMME procedure, including volume of 1-butyl-3-methylimidazolium hexafluorophosphate, amount of Fe3O4 magnetic nanoparticles, vortex time, amount of ammonium pyrrolidinedithiocarbamate, sample volume and matrix effect were optimized in details. Under the optimal conditions, the method present has low detection limit (0.57 μg L(-1)), high preconcentration factor (160) and good repeatability (<7.5%, n=10). The accuracy of the developed method was evaluated by the analysis of the certified reference materials and addition-recovery tests. The method was successfully applied to the determination of lead in water, plant and hair samples.

  4. Binding of fluoroanions by a cationic cobalt(III) complex: Syntheses, characterization and single crystal X-ray structure determination of [Co(phen) 2CO 3]BF 4 and [Co(phen) 2CO 3]PF 6·3H 2O

    NASA Astrophysics Data System (ADS)

    Sharma, Raj Pal; Singh, Ajnesh; Venugopalan, Paloth; Harrison, William T. A.

    2011-05-01

    In an effort to utilize the cationic cobalt(III) complex as a binding agent for fluoroanions, the reaction of carbonatobis(1,10-phenanthroline)cobalt(III) chloride with sodium tetrafluoroborate and sodium hexafluorophosphate in water (1:1 M ratio) leads to the formation of [Co(phen) 2CO 3]BF 4 ( 1) and [Co(phen) 2CO 3]PF 6·3H 2O ( 2). These cobalt(III) complex salts have been characterized by elemental analyses, spectroscopic techniques (multinuclear NMR, UV/Visible and FT-IR), solubility product and conductance measurements. X-ray structure determination of these complex salts revealed the presence of ionic structures i.e., one complex cation [Co(phen) 2CO 3] + and one BF4- anion in 1 and one complex cation [Co(phen) 2CO 3] +, one PF6- anion and three water molecules of crystallisation in 2. The packings in both complex salts are stabilized by C sbnd H⋯F, C sbnd H⋯O(carbonato) hydrogen bonds and anion⋯π interactions beside electrostatic forces of attraction. In addition to these non-covalent interactions, O sbnd H⋯O(water) and π-π stacking interactions are also observed in 2. The formation of complex salts of definite composition with tetrafluoroborate and hexafluorophosphate ions suggest that [Co(phen) 2CO 3] + may be used as binding agent for weakly coordinating fluoroanions i.e. BF4- and PF6-.

  5. Studies on structural, thermal and AC conductivity scaling of PEO-LiPF6 polymer electrolyte with added ionic liquid [BMIMPF6

    NASA Astrophysics Data System (ADS)

    Chaurasia, S. K.; Saroj, A. L.; Shalu, Singh, V. K.; Tripathi, A. K.; Gupta, A. K.; Verma, Y. L.; Singh, R. K.

    2015-07-01

    Preparation and characterization of polymer electrolyte films of PEO+10wt.% LiPF6 + xwt.% BMIMPF6 (1-butyl-3-methylimidazolium hexafluorophosphate) containing dopant salt lithium hexafluorophosphate (LiPF6) and ionic liquid (BMIMPF6) having common anion PF6 - are reported. The ionic conductivity of the polymer electrolyte films has been found to increase with increasing concentration of BMIMPF6 in PEO+10 wt.% LiPF6 due to the plasticization effect of ionic liquid. DSC and XRD results show that the crystallinity of polymer electrolyte decreases with BMIMPF6 concentration which, in turn, is responsible for the increase in ionic conductivity. FTIR spectroscopic study shows the complexation of salt and/or ionic liquid cations with the polymer backbone. Ion dynamics behavior of PEO+LiPF6 as well as PEO+LiPF6 + BMIMPF6 polymer electrolytes was studied by frequency dependent conductivity, σ(f) measurements. The values σ(f) at various temperatures have been analyzed in terms of Jonscher power law (JPL) and scaled with respect to frequency which shows universal power law characteristics at all temperatures.

  6. Electrochemical studies of hydrogen chloride gas in several room temperature ionic liquids: mechanism and sensing.

    PubMed

    Murugappan, Krishnan; Silvester, Debbie S

    2016-01-28

    The electrochemical behaviour of highly toxic hydrogen chloride (HCl) gas has been investigated in six room temperature ionic liquids (RTILs) containing imidazolium/pyrrolidinium cations and range of anions on a Pt microelectrode using cyclic voltammetry (CV). HCl gas exists in a dissociated form of H(+) and [HCl2](-) in RTILs. A peak corresponding to the oxidation of [HCl2](-) was observed, resulting in the formation of Cl2 and H(+). These species were reversibly reduced to H2 and Cl(-), respectively, on the cathodic CV scan. The H(+) reduction peak is also present initially when scanned only in the cathodic direction. In the RTILs with a tetrafluoroborate or hexafluorophosphate anion, CVs indicated a reaction of the RTIL with the analyte/electrogenerated products, suggesting that these RTILs might not be suitable solvents for the detection of HCl gas. This was supported by NMR spectroscopy experiments, which showed that the hexafluorophosphate ionic liquid underwent structural changes after HCl gas electrochemical experiments. The analytical utility was then studied in 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ([C2mim][NTf2]) by utilising both peaks (oxidation of [HCl2](-) and reduction of protons) and linear calibration graphs for current vs. concentration for the two processes were obtained. The reactive behaviour of some ionic liquids clearly shows that the choice of the ionic liquid is very important if employing RTILs as solvents for HCl gas detection.

  7. Cu(I)-N heterocyclic carbene complexes: Synthesis, catalysis and DFT studies

    NASA Astrophysics Data System (ADS)

    Dinda, Joydev; Roymahapatra, Gourisankar; Sarkar, Deblina; Mondal, Tapan K.; Al-Deyab, Salem S.; Sinha, Chittaranjan; Hwang, Wen-Shu

    2017-01-01

    The structural, spectroscopic and catalytic properties of the two Cu(I) complexes [Cu2(L1)2](PF6)2;(1) and [Cu2(L2)2](PF6)2; (2), bearing proligands 2,6-bis-(N-methylimidazolium)pyrazine hexafluorophosphate (L1) and 2,6-bis-(N-methylbenzimidazolium)pyrazine hexafluorophosphate (L2), have been investigated. The solid state structure of 1 has been determined by X-ray diffraction studies, while DFT computation technique has been used to optimize structure 2. From molecular orbital calculations using TD-DFT, the absorption bands are assigned to metal to ligand charge transfer(MLCT) along with some inter ligand charge transfer (ILCT) transitions. Complexes 1 and 2 possess very weak Cu(I)sbnd Cu(I) interactions within the reported distance 2.947-3.020 Å. They are expected to have luminescent properties due to Cu(I)sbnd Cu(I) interactions. Preliminary studies revealed both complexes to possess catalytic efficiency in general hydrosilylation reactions.

  8. The effect of the number of alkyl substituents on imidazolium ionic liquids phytotoxicity and oxidative stress in spring barley and common radish seedlings.

    PubMed

    Biczak, Robert; Pawłowska, Barbara; Telesiński, Arkadiusz; Ciesielski, Wojciech

    2016-12-01

    Increasing amounts of two ILs: 1-butyl-3-methylimidazolium hexafluorophosphate [BMIM][PF6] and 1-butyl-2,3-dimethylimidazolium hexafluorophosphate [BMMIM][PF6], were introduced to soil in which spring barley (Hordeum vulgare) and common radish (Raphanus sativus L. subvar. radicula Pers.) seedlings were cultivated, in order to evaluate the phytotoxicity of ionic liquids with imidazolium cation with two or three alkyl substituents attached. The results of the study i.e. the inhibition of the length of plants and their roots, as well as the yield of fresh weight of plants, clearly showed that differences in the number of substituents did not affect the toxicity of these ILs. Although, radish was more resistant to the applied ionic liquids than barley. Ionic liquids led to a decrease in the content of all assimilation pigments and induced oxidative stress in the plants, as showed by an increase in malondialdehyde (MDA) content, and changes in the level of H2O2 and antioxidant enzymes: superoxide dismutase (SOD), catalase (CAT) and peroxidase (POD). The best biomarkers of oxidative stress in both plants were the changes in chlorophyll content and the increase in POD activity. Both spring barley and radish exposed to [BMIM][PF6] and [BMMIM][PF6] accumulated a large amount of fluoride ions, which further increased the toxicity of these compounds for both plants.

  9. Ionic liquid-based dispersive liquid-liquid microextraction followed by RP-HPLC determination of saquinavir in rat serum: application to pharmacokinetics.

    PubMed

    Ramisetti, Nageswara Rao; Nimmu, Narendra Varma; Challa, Gangu Naidu

    2014-12-01

    An ionic liquid-based dispersive liquid-liquid microextraction followed by RP-HPLC determination of the most commonly prescribed protease inhibitor, saquinavir, in rat plasma was developed and validated. The effects of different ionic liquids, dispersive solvents, extractant/disperser ratio and salt concentration on sample recovery and enrichment were studied. Among the ionic liquids investigated, 1-butyl-3-methylimidazolium hexafluorophosphate was found to be most effective for extraction of saquinavir from rat serum. The recovery was found to be 95% at an extractant/disperser ratio of 0.43 using 1-butyl-3-methylimidazolium hexafluorophosphate and methanol as extraction and dispersive solvents. The recovery was further enhanced to 99.5% by addition of 5.0% NaCl. A threefold enhancement in detection and quantification limits was achieved, at 0.01 and 0.03 µg/mL, compared with the conventional protein precipitation method. A linear relationship was observed in the range of 0.035-10.0 µg/mL with a correlation coefficient (r(2) ) of 0.9996. The method was validated and applied to study pharmacokinetics of saquinavir in rat serum.

  10. Immobilization of pectinase on silica-based supports: Impacts of particle size and spacer arm on the activity.

    PubMed

    Alagöz, Dilek; Tükel, S Seyhan; Yildirim, Deniz

    2016-06-01

    The pectinase was separately immobilized onto Florisil and nano silica supports through both glutaraldehyde and 3-glyoxypropyltrietoxysilane spacer arms. The effects of spacer arm, particle size of support and ionic liquids on the activities of pectinase preparations were investigated. The immobilization of pectinase onto Florisil and nano silica through 3-glyoxypropyltrietoxysilane spacer arm completely led to inactivation of enzyme; however, 10 and 75% pectinase activity were retained when it was immobilized through glutaraldehyde spacer arm onto Florisil and nano silica, respectively. The pectinase immobilized onto nano silica through glutaraldehyde spacer arm showed 6.3-fold higher catalytic efficiency than that of the pectinase immobilized onto Florisil through same spacer arm. A 2.3-fold increase in thermal stability of pectinase was provided upon immobilization onto nano silica at 35°C. The effects of IL/buffer mixture and volume ratio of IL/buffer mixture on the catalytic activities of free and immobilized pectinase preparations were also tested. All the pectinase preparations showed highest activity in 10% (v/v) 1-butyl-3-methylimidazolium hexafluorophosphate containing medium and their activities significantly affected from the concentration of 1-butyl-3-methylimidazolium hexafluorophosphate.

  11. Determination of rifaximin in rat serum by ionic liquid based dispersive liquid-liquid microextraction combined with RP-HPLC.

    PubMed

    Rao, Ramisetti Nageswara; Vali, Rajavarapu Mastan; Rao, Alamanda Vara Prasada

    2012-08-01

    An efficient and environmental friendly ionic liquid based dispersive liquid-liquid microextraction procedure was optimized for determination of rifaximin in rat serum by reverse phase high-performance liquid chromatography. The effect of ionic liquids, dispersive solvents, extractant/disperser ratio, and salt concentrations on sample recovery and enrichment factors were studied. Among the five ionic liquids studied in the present investigation, 1-butyl-3-methylimidazolium hexafluorophosphate was found to be most effective for extraction of rifaximin. The recovery was found to be more than 98% using 1-butyl-3-methylimidazolium hexafluorophosphate and methanol as extraction and dispersive solvents, at an extractant/disperser ratio of 0.43. The recovery was further enhanced to 99.5% by the addition of 5.0% NaCl solution. A threefold enhancement in detection limit was achieved when compared to protein precipitation. The ionic liquid containing the extracted rifaximin was directly injected into HPLC system. The linear relationship was observed in the range of 0.03-10.0 μg/mL with the correlation coefficient (r(2)) 0.9998. Limits of detection and quantification were found to be 0.01 and 0.03 μg/mL, respectively. The relative standard deviation was 2.5%. The method was validated and applied to study pharmacokinetics of rifaxmin in rat serum.

  12. Electrochemical Investigation of Adsorption of Single‐Wall Carbon Nanotubes at a Liquid/Liquid Interface

    PubMed Central

    Rabiu, Aminu K.; Toth, Peter S.; Rodgers, Andrew N. J.

    2016-01-01

    Abstract There is much interest in understanding the interfacial properties of carbon nanotubes, particularly at water/oil interfaces. Here, the adsorption of single‐wall carbon nanotubes (SWCNTs) at the water/1,2‐dichloroethane (DCE) interface, and the subsequent investigation of the influence of the adsorbed nanotube layer on interfacial ion transfer, is studied by using the voltammetric transfer of tetramethylammonium (TMA+) and hexafluorophosphate (PF6 −) as probe ions. The presence of the interfacial SWCNT layer significantly suppresses the transfer of both ions across the interface, with a greater degree of selectivity towards the PF6 − ion. This effect was attributed both to the partial blocking of the interface by the SWCNTs and to the potential dependant adsorption of background electrolyte ions on the surface of the SWCNTs, as confirmed by X‐ray photoelectron spectroscopy, which is caused by an electrostatic interaction between the interfacial SWCNTs and the transferring ion. PMID:28168151

  13. Standard Thermodynamic Functions of Some Isolated Ions at 100{endash}1000 K

    SciTech Connect

    Loewenschuss, A.; Marcus, Y.

    1996-11-01

    The standard thermodynamic functions ({ital C}{sub {ital p}}{degree}, {ital S}{degree}, {ital H}{degree} and ({ital G}{degree}{minus}{ital H}{sub 0}{degree})/{ital T}) at 100 to 1000 K of 24 polyatomic gaseous ions are reported, based on structural and spectroscopic data from the literature. These ions supplement the 130 ions previously studied and are: zirconyl, hydrotelluride, amide, selenocyanate, tellurocyanate, orthoborate, metaphosphate, arsenite, orthosilicate, tetrachloropalladate(II), tetrabromopalladate(II), tetrachloroplatinate(II), tetrabromoplatinate(II), hexafluorophosphate, hexafluoroarsenate, hexafluoroantimonate, hexabromoplatinate(IV), tetracyanonickelate, tetracyanomercurate, octacyanomolybdate(IV), sulfamate, benzoate, guanidinium, and glycine as cation, zwitterion, and anion. {copyright} {ital 1996 American Institute of Physics and American Chemical Society.}

  14. Anion-tunable properties and electrochemical performance of functionalized ferrocene compounds

    SciTech Connect

    Cosimbescu, Lelia; Wei, Xiaoliang; Vijayakumar, M.; Xu, Wu; Helm, Monte L.; Burton, Sarah D.; Sorensen, Christina M.; Liu, Jun; Sprenkle, Vincent; Wang, Wei

    2015-09-16

    We report a series of ionically modified ferrocene compounds for hybrid lithium-organic non-aqueous redox flow batteries, based on the ferrocene/ferrocenium redox couple as the active catholyte material. Tetraalkylammonium ionic moieties were incorporated into the ferrocene structure, in order to enhance the solubility of the otherwise relatively insoluble ferrocene. The effect of various counter anions of the tetraalkylammonium ionized species appended to the ferrocene, such as bis(trifluoromethanesulfonyl)imide, hexafluorophosphate, perchlorate, tetrafluoroborate, and dicyanamide on the solubility of the ferrocene was investigated. The solution chemistry of the ferrocene species was studied, in order to understand the mechanism of solubility enhancement. Lastly, the electrochemical performance of these ionized ferrocene species was evaluated and shown to have excellent cell efficiency and superior cycling stability.

  15. Effect of anions on the electrochemistry of zinc tetraphenylporphyrin

    SciTech Connect

    Seely, G.R.; Gust, D.; Moore, T.A.; Moore, A.L. )

    1994-10-13

    Accurate measurements of porphyrin redox potentials are essential for the prediction and rationalization of the rates of electron transfer reactions involving these biologically important electron-donating and accepting chromophores. The present work describes a survey of redox potentials of zinc tetraphenylporphyrin obtained by cyclic voltammetry in dichloromethane, with tetrabutylammonium salts containing a variety of anions as electrolytes. Of the anions tested, hexafluorophosphate appears to have the least ability to ligate the metal, so that potentials measured in its presence as electrolyte should most closely approach those of the unligated porphyrin. With perchlorate electrolyte, the potential for one-electron oxidation is approximately 80 mV lower, enough to affect the interpretation of photochemical electron transfer rates. In general, anions bind much more strongly to the cation radical than to zinc tetraphenylporphyrin itself. The use of reference redox systems based on thymoquinone and ferrocene carboxylate enabled comparison of potentials measured with different electrolytes. 30 refs., 2 tabs.

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

    SciTech Connect

    Zuo, Y.; Chen, J.; Bai, Y.; Li, D.Q.

    2008-07-01

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

  17. Ionic-liquid-assisted synthesis of YF{sub 3} with different crystalline phases and morphologies

    SciTech Connect

    Zhong Haoxiang; Hong Jianming; Cao Xiaofeng; Chen Xuetai Xue Ziling

    2009-03-05

    YF{sub 3} with different crystalline phases and morphologies have been prepared via a facile hydrothermal route assisted by imidazolium ionic liquids 1-butyl-3-methylimidazolium tetrafluoroborate (C{sub 4}mimBF{sub 4}) or 1-butyl-3-methylimidazolium hexafluorophosphate (C{sub 4}mimPF{sub 6}). The microstructures and morphologies of YF{sub 3} particles were characterized by X-ray powder diffraction, X-ray photoelectron spectra (XPS), transmission electron microscopy (TEM), high resolution electron microscopy (HRTEM) and field emission scanning electron microscopy (FESEM). Cubic and orthorhombic YF{sub 3} were selectively synthesized by adjusting the molar ratio of the reagents and using C{sub 4}mimBF{sub 4} as the fluoride source, while only orthorhombic YF{sub 3} was obtained using C{sub 4}mimPF{sub 6}, indicating that the crystalline phases and morphologies of the products were significantly influenced by fluoride source and reaction media.

  18. Anion Solvation in Carbonate-Based Electrolytes

    SciTech Connect

    von Wald Cresce, Arthur; Gobet, Mallory; Borodin, Oleg; Peng, Jing; Russell, Selena M.; Wikner, Emily; Fu, Adele; Hu, Libo; Lee, Hung-Sui; Zhang, Zhengcheng; Yang, Xiao-Qing; Greenbaum, Steven; Amine, Khalil; Xu, Kang

    2015-11-16

    The correlation between Li+ solvation and interphasial chemistry on anodes firmly established in Li-ion batteries, the effect of cation–solvent interaction has gone beyond bulk thermodynamic and transport properties and become an essential element that determines the reversibility of electrochemistry and kinetics of Li-ion intercalation chemistries. Now, most studies are dedicated to the solvation of Li+, and the solvation of anions in carbonate-based electrolytes and its possible effect on the electrochemical stability of such electrolytes remains little understood. Moreover, as a mirror effort to prior Li+ solvation studies, this work focuses on the interactions between carbonate-based solvents and two anions (hexafluorophosphate, PF6–, and tetrafluoroborate, BF4–) that are most frequently used in Li-ion batteries. The possible correlation between such interaction and the interphasial chemistry on cathode surface is also explored.

  19. Incorporation of quaternary ammonium salts containing different counterions to improve the performance of inverted perovskite solar cells

    NASA Astrophysics Data System (ADS)

    Yan, Po-Ruei; Huang, Wei-Jie; Yang, Sheng-Hsiung

    2017-02-01

    In this research, three quaternary ammonium salts containing different counterions, including tetrabutylammonium bromide (TBABr), tetrabutylammonium tetrafluoroborate (TBABF4), and tetrabutylammonium hexafluorophosphate (TBAPF6), were incorporated into [6,6]-phenyl-C61 butyric acid methyl ester (PCBM) as electron transporting layer (ETL). These salts-doped PCBM films revealed higher electron mobility and Fermi levels compared with the un-doped one. Better charge transfer at the interface between perovskite and salts-doped PCBM was also obtained from PL quenching experiments. Inverted perovskite solar cells with the configuration of ITO/PEDOT:PSS/CH3NH3PbI3/PCBM + salts/Ag were fabricated, and the JSC and FF of devices were significantly enhanced using salts-doped PCBM as ETL. The best device based on TBABF4-doped PCBM delivered a power conversion efficiency (PCE) up to 13.41%, which was superior to the one with undoped PCBM layer (PCE = 8.77%).

  20. Effect of simultaneous electrical and thermal treatment on the performance of bulk heterojunction organic solar cell blended with organic salt

    SciTech Connect

    Sabri, Nasehah Syamin; Yap, Chi Chin; Yahaya, Muhammad; Salleh, Muhamad Mat

    2013-11-27

    This work presents the influence of simultaneous electrical and thermal treatment on the performance of organic solar cell blended with organic salt. The organic solar cells were composed of indium tin oxide as anode, poly[2-methoxy-5-(2-ethylhexyloxy)-1,4-phenylenevinylene]: (6,6)-phenyl-C61 butyric acid methyl ester: tetrabutylammonium hexafluorophosphate blend as organic active layer and aluminium as cathode. The devices underwent a simultaneous fixed-voltage electrical and thermal treatment at different temperatures of 25, 50 and 75 °C. It was found that photovoltaic performance improved with the thermal treatment temperature. Accumulation of more organic salt ions in the active layer leads to broadening of p-n doped regions and hence higher built-in electric field across thin intrinsic layer. The simultaneous electrical and thermal treatment has been shown to be able to reduce the electrical treatment voltage.

  1. Piperidinium, piperazinium and morpholinium ionic liquid crystals.

    PubMed

    Lava, Kathleen; Binnemans, Koen; Cardinaels, Thomas

    2009-07-16

    Piperidinium, piperazinium and morpholinium cations have been used for the design of ionic liquid crystals. These cations were combined with several types of anions, namely bromide, tetrafluoroborate, hexafluorophosphate, dodecylsulfate, bis(trifluoromethylsulfonyl)imide, dioctylsulfosuccinate, dicyclohexylsulfosuccinate, and dihexylsulfosuccinate. For the bromide salts of piperidinium containing one alkyl chain, the chain length was varied, ranging from 8 to 18 carbon atoms (n = 8, 10, 12, 14, 16, 18). The compounds show a rich mesomorphic behavior. High-ordered smectic phases (crystal smectic E and T phases), smectic A phases, and hexagonal columnar phases were observed, depending on the type of cation and anion. The morpholinium compounds with sulfosuccinate anions showed hexagonal columnar phases at room temperature and a structural model for the self-assembly of these morpholinium compounds into hexagonal columnar phases is proposed.

  2. Surface Nanocrystallization of an Ionic Liquid

    SciTech Connect

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

    2012-03-26

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

  3. Anion Solvation in Carbonate Electrolytes

    SciTech Connect

    Zhang, Zhengcheng

    2015-11-16

    With the correlation between Li+ solvation and interphasial chemistry on anodes firmly established in Li-ion batteries, the effect of cation–solvent interaction has gone beyond bulk thermodynamic and transport properties and become an essential element that determines the reversibility of electrochemistry and kinetics of Li-ion intercalation chemistries. As of now, most studies are dedicated to the solvation of Li+, and the solvation of anions in carbonate-based electrolytes and its possible effect on the electrochemical stability of such electrolytes remains little understood. As a mirror effort to prior Li+ solvation studies, this work focuses on the interactions between carbonate-based solvents and two anions (hexafluorophosphate, PF6–, and tetrafluoroborate, BF4–) that are most frequently used in Li-ion batteries. The possible correlation between such interaction and the interphasial chemistry on cathode surface is also explored.

  4. Electronic influence of β-diketonato-type ligands on the coordination of 1,5-cyclooctadiene to palladium(II) as defined by 'Venus fly trap' geometric parameters.

    PubMed

    Hill, Tania N; Roodt, Andreas; Steyl, Gideon

    2013-02-01

    A range of single-crystal structures of the type [Pd(cod)(LL'-Bid)]A, where LL'-Bid = acetylacetonato (acac), thenoyltrifluoroactetonato (thtfac) and hexafluoroacetylacetonato (hfacac), and A = tetrafluoroborate (BF(4)(-)) and hexafluorophosphate (PF(6)(-)), are reported. The complexes [Pd(cod)(acac)]PF(6) (I), [Pd(cod)(thtfac)]PF(6) (III), [Pd(cod)(thtfac)]BF(4) (IV) and [Pd(cod)(hfacac)]PF(6) (V) are isostructural in the monoclinic space group P2(1)/c. The influence of the variation of the β-diketonato-type ligands on the coordination geometry of cis,cis-1,5-cycloocta-1,5-diene (cod) was investigated and found that no significant changes to the Pd-C and C=C bond distances were observed. The `Venus fly trap' parameters vary by 7.8° for the 'jaw' angle (ψ), while the `bite' angle (χ) remains virtually constant.

  5. Thermophysical properties of LiFePO4 cathodes with carbonized pitch coatings and organic binders: Experiments and first-principles modeling

    NASA Astrophysics Data System (ADS)

    Nanda, Jagjit; Martha, Surendra K.; Porter, Wallace D.; Wang, Hsin; Dudney, Nancy J.; Radin, Maxwell D.; Siegel, Donald J.

    2014-04-01

    We report heat capacity, thermogravimetry and thermal diffusivity data for carbonized mesophase pitch coated LiFePO4 (LFP) cathodes. The results are compared with the thermophysical properties of a conventional LFP-based electrode having a poly (vinylene) difluoride (PVDF) binder and conductive carbon diluents. The measured heat capacity of LFP as a function of temperature is in good agreement with model calculations based on first-principles methods. Thermal diffusivity data indicate that the mesophase pitch coated LFP compositions have a factor of two higher thermal diffusivity than the conventional electrode composition, suggesting that the coatings improve heat transfer. In the presence of an electrolyte mixture (1.2 M lithium hexa-fluorophosphate), differential scanning calorimetry (DSC) analysis of the LFP-pitch composite and LFP-PVDF-carbon composites showed similar onset temperature and heat evolution.

  6. Radiofrequency attenuator and method

    DOEpatents

    Warner, Benjamin P.; McCleskey, T. Mark; Burrell, Anthony K.; Agrawal, Anoop; Hall, Simon B.

    2009-11-10

    Radiofrequency attenuator and method. The attenuator includes a pair of transparent windows. A chamber between the windows is filled with molten salt. Preferred molten salts include quarternary ammonium cations and fluorine-containing anions such as tetrafluoroborate (BF.sub.4.sup.-), hexafluorophosphate (PF.sub.6.sup.-), hexafluoroarsenate (AsF.sub.6.sup.-), trifluoromethylsulfonate (CF.sub.3SO.sub.3.sup.-), bis(trifluoromethylsulfonyl)imide ((CF.sub.3SO.sub.2).sub.2N.sup.-), bis(perfluoroethylsulfonyl)imide ((CF.sub.3CF.sub.2SO.sub.2).sub.2N.sup.-) and tris(trifluoromethylsulfonyl)methide ((CF.sub.3SO.sub.2).sub.3 C.sup.-). Radicals or radical cations may be added to or electrochemically generated in the molten salt to enhance the RF attenuation.

  7. Radiofrequency attenuator and method

    DOEpatents

    Warner, Benjamin P.; McCleskey, T. Mark; Burrell, Anthony K.; Agrawal, Anoop; Hall, Simon B.

    2009-01-20

    Radiofrequency attenuator and method. The attenuator includes a pair of transparent windows. A chamber between the windows is filled with molten salt. Preferred molten salts include quarternary ammonium cations and fluorine-containing anions such as tetrafluoroborate (BF.sub.4.sup.-), hexafluorophosphate (PF.sub.6.sup.-), hexafluoroarsenate (AsF.sub.6.sup.-), trifluoromethylsulfonate (CF.sub.3SO.sub.3.sup.-), bis(trifluoromethylsulfonyl)imide ((CF.sub.3SO.sub.2).sub.2N.sup.-), bis(perfluoroethylsulfonyl)imide ((CF.sub.3CF.sub.2SO.sub.2).sub.2N.sup.-) and tris(trifluoromethylsulfonyl)methide ((CF.sub.3SO.sub.2).sub.3C.sup.-). Radicals or radical cations may be added to or electrochemically generated in the molten salt to enhance the RF attenuation.

  8. FTIR studies of organometalcarbonyl-tagged enzymes

    NASA Astrophysics Data System (ADS)

    Anson, Christopher E.; Creaser, Colin S.; Egyed, Orsolya; Stephenson, G. Richard

    1997-10-01

    Attachment of organometaltricarbonyl tags to enzymes is revealed by changes in the vibrational modes of the carbonyl groups. Shoulders on νsym( CO) and νasym( CO) bands in the FTIR spectrum of an organometallic tag derived from tricarbonyl[1-{(2,3,4,5-η)-2,4-cyclohexadien-1-yl}pyridinium]iron(1 +) hexafluorophosphate(1 -) were detected on binding to enzymes (α-chymotrypsin, ribonuclease A, alkaline phosphatase and a triacylglycerol lipase). By comparison with tagging reactions between the tricarbonyliron moiety and model compounds, the new spectral features were attributed to an iron complex covalently bonded to the NH 2 groups of the amino acid residues of the enzymes. FTIR spectroscopy was used to monitor deprotonation of tagged amino groups on the enzyme surface. Interactions between the organometalcarbonyl tag and other side-chain groups of the amino acid residues were also investigated.

  9. Lithium Ethylene Dicarbonate Identified as the Primary Product ofChemical and Electrochemical Reduction of EC in EC:EMC/1.2M LiPF6Electrolyte

    SciTech Connect

    Zhuang, Guorong V.; Xu, Kang; Yang, Hui; Jow, T. Richard; RossJr., Philip N.

    2005-05-11

    Lithium ethylene dicarbonate (CH2OCO2Li)2 was chemically synthesized and its Fourier Transform Infrared (FTIR) spectrum was obtained and compared with that of surface films formed on Ni after cyclic voltammetry (CV) in 1.2M lithium hexafluorophosphate(LiPF6)/ethylene carbonate (EC): ethyl methyl carbonate (EMC) (3:7, w/w) electrolyte and on metallic lithium cleaved in-situ in the same electrolyte. By comparison of IR experimental spectra with that of the synthesized compound, we established that the title compound is the predominant surface species in both instances. Detailed analysis of the IR spectrum utilizing quantum chemical (Hartree-Fock) calculations indicates that intermolecular association through O...Li...O interactions is very important in this compound. It is likely that the title compound in passivation layer has a highly associated structure, but the exact intermolecular conformation could not be established based on analysis of the IR spectrum.

  10. An electrochemical fungicide pyrimethanil sensor based on carbon nanotubes/ionic-liquid construction modified electrode.

    PubMed

    Yang, Jichun; Wang, Qiong; Zhang, Minhui; Zhang, Shuming; Zhang, Lei

    2015-11-15

    In this study, a simple, rapid, sensitive and environmentally friendly electroanalytical detection method for pyrimethanil (PMT) was developed, which was based on multi-walled carbon nanotubes (MWCNTs) and ionic liquids (IL) 1-butyl-3-methylimidazolium hexafluorophosphate ([BMIM][PF6]) modified glassy carbon electrode (GCE). MWCNTs-IL modified electrode significantly enhanced the oxidation peak current of PMT by combining the excellent electrochemical properties of MWCNTs and IL, suggesting that the modified electrode can remarkably improve the sensitivity of PMT detection. Under the optimum conditions, this electrochemical sensor exhibited a linear concentration range for PMT of 1.0 × 10(-7)-1.0 × 10(-4) mol L(-1) and the detection limit was 1.6 × 10(-8) mol L(-1) (S/N = 3). The fabricated electrode showed good reproducibility, stability and anti-interference, and also it was successfully employed to detect PMT in real samples.

  11. X-ray diffraction and vibrational spectroscopic study of trans-bis(acetylacetonato)-bis(4-methylpyridine)cobalt(III)

    NASA Astrophysics Data System (ADS)

    Tayyari, Sayyed Faramarz; Habibi, Mohammad Hossien; Shojaee, Elahe; Jamialahmadi, Mina; Sammelson, Robert Erik; Wada, Koki; Suzuki, Takayoshi

    2015-03-01

    Trans-bis(acetylacetonato)-bis(4-methylpyridine)cobalt(III)hexafluorophosphate, [AMPC]PF6, was synthesized and characterized by X-ray diffraction and vibrational spectroscopy. The title compound C22H28N2O4Co crystallizes with Z = 2 in space group P-1 (#2). The molecular structure and vibrational spectra of this compound were investigated by means of density functional theory (DFT) calculations and the results were compared with the experimental data. The measured IR bands were interpreted in terms of the calculated vibrational normal modes and compared with the tris(acetylacetonate)Co(III) (Co(acac)3) and 4-methylpyridine (4-Mepy) vibrational spectra. The scaled theoretical wavenumbers and the structural parameters were in excellent agreement with the experimental data.

  12. Anion-tunable properties and electrochemical performance of functionalized ferrocene compounds

    DOE PAGES

    Cosimbescu, Lelia; Wei, Xiaoliang; Vijayakumar, M.; ...

    2015-09-16

    We report a series of ionically modified ferrocene compounds for hybrid lithium-organic non-aqueous redox flow batteries, based on the ferrocene/ferrocenium redox couple as the active catholyte material. Tetraalkylammonium ionic moieties were incorporated into the ferrocene structure, in order to enhance the solubility of the otherwise relatively insoluble ferrocene. The effect of various counter anions of the tetraalkylammonium ionized species appended to the ferrocene, such as bis(trifluoromethanesulfonyl)imide, hexafluorophosphate, perchlorate, tetrafluoroborate, and dicyanamide on the solubility of the ferrocene was investigated. The solution chemistry of the ferrocene species was studied, in order to understand the mechanism of solubility enhancement. Lastly, the electrochemicalmore » performance of these ionized ferrocene species was evaluated and shown to have excellent cell efficiency and superior cycling stability.« less

  13. Peptide bond-forming reagents HOAt and HATU are not mutagenic in the bacterial reverse mutation test.

    PubMed

    Nicolette, John; Neft, Robin E; Vanosdol, Jessica; Murray, Joel

    2016-04-01

    The peptide bond-forming reagents 1-hydroxy-7-azabenzotriazole (HOAt, CAS 39968-33-7) and O-(7-Azabenzotriazol-1-yl)-N,N,N',N'-tetramethyluronium hexafluorophosphate (HATU, CAS 148893-10-1) either have structural alerts, unclassified features or are considered out of domain when evaluated for potential mutagenicity with in silico programs DEREK and CaseUltra. Since they are commonly used reagents in pharmaceutical drug syntheses, they may become drug substance or drug product impurities and would need to be either controlled to appropriately safe levels or tested for mutagenicity. Both reagents were tested in the bacterial reverse mutation (Ames) test at Covance, under GLP conditions, following the OECD test guideline and ICH S2(R1) recommendations and found to be negative. Our data show that HOAt and HATU-common pharmaceutical synthesis reagents-are not mutagenic, and can be treated as ordinary drug impurities.

  14. Lithium insertion in graphite from ternary ionic liquid-lithium salt electrolytes: II. Evaluation of specific capacity and cycling efficiency and stability at room temperature

    NASA Astrophysics Data System (ADS)

    Lux, Simon F.; Schmuck, Martin; Appetecchi, Giovanni B.; Passerini, Stefano; Winter, Martin; Balducci, Andrea

    In this paper we report the results about the use of ternary room temperature ionic liquid-lithium salt mixtures as electrolytes for lithium-ion battery systems. Mixtures of N-methyl- N-propyl pyrrolidinium bis(fluorosulfonyl) imide, PYR 13FSI, and N-butyl- N-methylpyrrolidinium bis(trifluoromethansulfonyl) imide, PYR 14TFSI, with lithium hexafluorophosphate, LiPF 6 and lithium bis(trifluoromethansulfonyl) imide, LiTFSI, containing 5 wt.% of vinylene carbonate (VC) as additive, have been used in combination with a commercial graphite, KS6 TIMCAL. The performance of the graphite electrodes has been considered in term of specific capacity, cycling efficiency and cycling stability. The results clearly show the advantage of the use of ternary mixtures on the performance of the graphite electrode.

  15. Lithium salts for advanced lithium batteries: Li-metal, Li-O2, and Li-S

    DOE PAGES

    Younesi, Reza; Veith, Gabriel M.; Johansson, Patrik; ...

    2015-06-01

    Presently lithium hexafluorophosphate (LiPF6) is the dominant Li-salt used in commercial rechargeable lithium-ion batteries (LIBs) based on a graphite anode and a 3-4 V cathode material. While LiPF6 is not the ideal Li-salt for every important electrolyte property, it has a uniquely suitable combination of properties (temperature range, passivation, conductivity, etc.) rendering it the overall best Li-salt for LIBs. However, this may not necessarily be true for other types of Li-based batteries. Indeed, next generation batteries, for example lithium-metal (Li-metal), lithium-oxygen (Li-O2), and lithium sulphur (Li-S), require a re-evaluation of Li-salts due to the different electrochemical and chemical reactions andmore » conditions within such cells. Furthermore, this review explores the critical role Li-salts play in ensuring in these batteries viability.« less

  16. Lithium salts for advanced lithium batteries: Li-metal, Li-O2, and Li-S

    SciTech Connect

    Younesi, Reza; Veith, Gabriel M.; Johansson, Patrik; Edstrom, Kristina; Vegge, Tejs

    2015-06-01

    Presently lithium hexafluorophosphate (LiPF6) is the dominant Li-salt used in commercial rechargeable lithium-ion batteries (LIBs) based on a graphite anode and a 3-4 V cathode material. While LiPF6 is not the ideal Li-salt for every important electrolyte property, it has a uniquely suitable combination of properties (temperature range, passivation, conductivity, etc.) rendering it the overall best Li-salt for LIBs. However, this may not necessarily be true for other types of Li-based batteries. Indeed, next generation batteries, for example lithium-metal (Li-metal), lithium-oxygen (Li-O2), and lithium sulphur (Li-S), require a re-evaluation of Li-salts due to the different electrochemical and chemical reactions and conditions within such cells. Furthermore, this review explores the critical role Li-salts play in ensuring in these batteries viability.

  17. Performance of Liquid Phase Exfoliated Graphene As Electrochemical Double Layer Capacitors Electrodes

    NASA Astrophysics Data System (ADS)

    Huffstutler, Jacob; Wasala, Milinda; Richie, Julianna; Winchester, Andrew; Ghosh, Sujoy; Kar, Swastik; Talapatra, Saikat

    2014-03-01

    We will present the results of our investigations of electrochemical double layer capacitors (EDLCs) or supercapacitors (SC) fabricated using liquid-phase exfoliated graphene. Several electrolytes, such as aqueous potassium hydroxide KOH (6M), ionic 1-Butyl-3-methylimidazolium hexafluorophosphate [BMIM][PF6], and ionic 1-butyl-1-methylpyrrolidinium tris(pentafluoroethyl)trifluorophosphate[BMP][FAP] were used. These EDLC's show good performance compared to other carbon nanomaterials based EDLC's devices. We found that the liquid phase exfoliated graphene based devices possess specific capacitance values as high as 262 F/g, when used with ionic liquid electrolyte[BMP][FAP], with power densities (~ 454 W/kg) and energy densities (~ 0.38Wh/kg). Further, these devices indicated rapid charge transfer response even without the use of any binders or specially prepared current collectors. A detailed electrochemical impedance spectroscopy analysis in order to understand the phenomenon of charge storage in these materials will be presented.

  18. Measurement of conductivity and permittivity on samples sealed in nuclear magnetic resonance tubes

    SciTech Connect

    Huang, W.; Angell, C. A.; Yarger, J. L.; Richert, R.

    2013-07-15

    We present a broadband impedance spectroscopy instrument designed to measure conductivity and/or permittivity for samples that are sealed in glass tubes, such as the standard 5 mm tubes used for nuclear magnetic resonance experiments. The calibrations and corrections required to extract the dielectric properties of the sample itself are outlined. It is demonstrated that good estimates of the value of dc-conductivity can be obtained even without correcting for the effects of glass or air on the overall impedance. The approach is validated by comparing data obtained from samples sealed in nuclear magnetic resonance tubes with those from standard dielectric cells, using glycerol and butylmethylimidazolium-hexafluorophosphate as respective examples of a molecular and an ionic liquid. This instrument and approach may prove useful for other studies of permittivity and conductivity where contact to the metal electrodes or to the ambient atmosphere needs to be avoided.

  19. Application of a nanostructured sensor based on NiO nanoparticles modified carbon paste electrode for determination of methyldopa in the presence of folic acid

    NASA Astrophysics Data System (ADS)

    Fouladgar, Masoud; Ahmadzadeh, Saeid

    2016-08-01

    A new method for determination of methyldopa in the presence of folic acid has been described in this work. This method is based on modification of carbon paste electrode with NiO nanoparticles and an ionic liquid (1-Butyl-3-methylimidazolium hexafluorophosphate). Electrochemical studies showed that on the surface of modified electrode, oxidation current of methyldopa has been enhanced and shifted to negative potentials. The fabricated electrode exhibited a linear response to concentration of methyldopa from 0.1 to 700.0 μmol L-1. The sensitivity of the modified electrode to methyldopa not changed in the presence of folic acid and simultaneous or independent measurements of them are possible. The performance of proposed method was investigated by determination of methyldopa in real samples.

  20. Anion-Tunable Properties and Electrochemical Performance of Functionalized Ferrocene Compounds

    PubMed Central

    Cosimbescu, Lelia; Wei, Xiaoliang; Vijayakumar, M.; Xu, Wu; Helm, Monte L.; Burton, Sarah D.; Sorensen, Christina M.; Liu, Jun; Sprenkle, Vincent; Wang, Wei

    2015-01-01

    We report a series of ionically modified ferrocene compounds for hybrid lithium-organic non-aqueous redox flow batteries, based on the ferrocene/ferrocenium redox couple as the active catholyte material. Tetraalkylammonium ionic moieties were incorporated into the ferrocene structure, in order to enhance the solubility of the otherwise relatively insoluble ferrocene. The effect of various counter anions of the tetraalkylammonium ionized species appended to the ferrocene, such as bis(trifluoromethanesulfonyl)imide, hexafluorophosphate, perchlorate, tetrafluoroborate, and dicyanamide on the solubility of the ferrocene was investigated. The solution chemistry of the ferrocene species was studied, in order to understand the mechanism of solubility enhancement. Finally, the electrochemical performance of these ionized ferrocene species was evaluated and shown to have excellent cell efficiency and superior cycling stability. PMID:26374254

  1. Light-assisted delithiation of lithium iron phosphate nanocrystals towards photo-rechargeable lithium ion batteries.

    PubMed

    Paolella, Andrea; Faure, Cyril; Bertoni, Giovanni; Marras, Sergio; Guerfi, Abdelbast; Darwiche, Ali; Hovington, Pierre; Commarieu, Basile; Wang, Zhuoran; Prato, Mirko; Colombo, Massimo; Monaco, Simone; Zhu, Wen; Feng, Zimin; Vijh, Ashok; George, Chandramohan; Demopoulos, George P; Armand, Michel; Zaghib, Karim

    2017-04-10

    Recently, intensive efforts are dedicated to convert and store the solar energy in a single device. Herein, dye-synthesized solar cell technology is combined with lithium-ion materials to investigate light-assisted battery charging. In particular we report the direct photo-oxidation of lithium iron phosphate nanocrystals in the presence of a dye as a hybrid photo-cathode in a two-electrode system, with lithium metal as anode and lithium hexafluorophosphate in carbonate-based electrolyte; a configuration corresponding to lithium ion battery charging. Dye-sensitization generates electron-hole pairs with the holes aiding the delithiation of lithium iron phosphate at the cathode and electrons utilized in the formation of a solid electrolyte interface at the anode via oxygen reduction. Lithium iron phosphate acts effectively as a reversible redox agent for the regeneration of the dye. Our findings provide possibilities in advancing the design principles for photo-rechargeable lithium ion batteries.

  2. Development of Ionic Liquid Modified Disposable Graphite Electrodes for Label-Free Electrochemical Detection of DNA Hybridization Related to Microcystis spp.

    PubMed

    Sengiz, Ceren; Congur, Gulsah; Erdem, Arzum

    2015-09-09

    In this present study, ionic liquid (1-butyl-3-methylimidazolium hexafluorophosphate (IL)) modified pencil graphite electrode (IL-PGEs) was developed for electrochemical monitoring of DNA hybridization related to Microcystis spp. (MYC). The characterization of IL-PGEs was performed using microscopic and electrochemical techniques. DNA hybridization related to MYC was then explored at the surface of IL-PGEs using differential pulse voltammetry (DPV) technique. After the experimental parameters were optimized, the sequence-selective DNA hybridization related to MYC was performed in the case of hybridization between MYC probe and its complementary DNA target, noncomplementary (NC) or mismatched DNA sequence (MM), or and in the presence of mixture of DNA target: NC (1:1) and DNA target: MM (1:1).

  3. Development of Ionic Liquid Modified Disposable Graphite Electrodes for Label-Free Electrochemical Detection of DNA Hybridization Related to Microcystis spp.

    PubMed Central

    Sengiz, Ceren; Congur, Gulsah; Erdem, Arzum

    2015-01-01

    In this present study, ionic liquid (1-butyl-3-methylimidazolium hexafluorophosphate (IL)) modified pencil graphite electrode (IL-PGEs) was developed for electrochemical monitoring of DNA hybridization related to Microcystis spp. (MYC). The characterization of IL-PGEs was performed using microscopic and electrochemical techniques. DNA hybridization related to MYC was then explored at the surface of IL-PGEs using differential pulse voltammetry (DPV) technique. After the experimental parameters were optimized, the sequence-selective DNA hybridization related to MYC was performed in the case of hybridization between MYC probe and its complementary DNA target, noncomplementary (NC) or mismatched DNA sequence (MM), or and in the presence of mixture of DNA target: NC (1:1) and DNA target: MM (1:1). PMID:26371004

  4. Self-Assembly of Block Copolymers in an Ionic Liquid

    NASA Astrophysics Data System (ADS)

    He, Yiyong; Li, Zhibo; Lodge, Timothy P.

    2006-03-01

    Amphiphilic diblock copolymers poly((1,2-butadiene)-b-ethylene oxide) (PB-PEO) were shown to aggregate and form well-defined micelles in an ionic liquid, 1-butyl-3-methyl imidazolium hexafluorophosphate ([BMIM][PF6]). The universal sequence of micellar structures (spherical micelle, wormlike micelle, and bilayered vesicle) were all resolved by varying the block copolymer composition. For the first time, the nanostructures of PB-PEO micelles formed in an ionic liquid were directly visualized by cryogenic transmission electron microscopy (cryo-TEM). The detailed micelle structure information was extracted from cryo-TEM and dynamic light scattering (DLS) measurements, and compared to their aqueous counterparts. The work demonstrates the feasibility of controlling micellar nanostructures of amphiphilic block copolymers in ionic liquids, and also provides important knowledge for further applications of copolymers for forming microemulsions and ion gels.

  5. Lithium insertion in graphite from ternary ionic liquid-lithium salt electrolytes. I. Electrochemical characterization of the electrolytes

    NASA Astrophysics Data System (ADS)

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

    In this paper we report the results of chemical-physical investigation performed on ternary room temperature ionic liquid-lithium salt mixtures as electrolytes for lithium-ion battery systems. The ternary electrolytes were made by mixing N-methyl- N-propyl pyrrolidinium bis(fluorosulfonyl) imide (PYR 13FSI) and N-butyl- N-methylpyrrolidinium bis(trifluoromethanesulfonyl) imide (PYR 14TFSI) ionic liquids with lithium hexafluorophosphate (LiPF 6) or lithium bis(trifluoromethanesulfonyl)imide (LiTFSI). The mixtures were developed based on preliminary results on the cyclability of graphite electrodes in the IL-LiX binary electrolytes. The results clearly show the beneficial synergic effect of the two ionic liquids on the electrochemical properties of the mixtures.

  6. Anion-Tunable Properties and Electrochemical Performance of Functionalized Ferrocene Compounds

    NASA Astrophysics Data System (ADS)

    Cosimbescu, Lelia; Wei, Xiaoliang; Vijayakumar, M.; Xu, Wu; Helm, Monte L.; Burton, Sarah D.; Sorensen, Christina M.; Liu, Jun; Sprenkle, Vincent; Wang, Wei

    2015-09-01

    We report a series of ionically modified ferrocene compounds for hybrid lithium-organic non-aqueous redox flow batteries, based on the ferrocene/ferrocenium redox couple as the active catholyte material. Tetraalkylammonium ionic moieties were incorporated into the ferrocene structure, in order to enhance the solubility of the otherwise relatively insoluble ferrocene. The effect of various counter anions of the tetraalkylammonium ionized species appended to the ferrocene, such as bis(trifluoromethanesulfonyl)imide, hexafluorophosphate, perchlorate, tetrafluoroborate, and dicyanamide on the solubility of the ferrocene was investigated. The solution chemistry of the ferrocene species was studied, in order to understand the mechanism of solubility enhancement. Finally, the electrochemical performance of these ionized ferrocene species was evaluated and shown to have excellent cell efficiency and superior cycling stability.

  7. Time Scales of Ion Transport in Imidazolium-based Polymers

    NASA Astrophysics Data System (ADS)

    Choi, U. Hyeok; Ye, Yuesheng; Lee, Minjae; Gibson, Harry; Elabd, Yossef; Runt, James; Colby, Ralph

    2011-03-01

    We synthesize and characterize ionic polymers with imidazolium cations covalently attached to the polymer chain and various ionic liquid counterions for ionic actuators. The imidazolium cations are attached to the polymers with flexible alkyl spacer chains and also have a variety of alkyl and alkyl ether termini. The anionic counterions are also varied; tetrafluoroborate (BF4) , hexafluorophosphate (PF6) and bis(trifluoromethanesulfonyl)imide (TFSI) were mainly used in this study. Dielectric relaxation spectroscopy (DRS) is utilized to measure the dielectric constant and conductivity, as a function of temperature. The 1953 Macdonald model is applied to estimate the number density of conducting ions and their mobility, from electrode polarization at low frequencies in DRS. The 1988 Dyre model is used to determine ion hopping times from the frequency-dependent conductivity at higher frequencies. The consequence of polymer structural variations will be elucidated for these vital characteristics.

  8. Application of multiwalled carbon nanotubes/ionic liquid modified electrode for amperometric determination of sulfadiazine.

    PubMed

    Hong, Xiaoping; Zhu, Yan; Ma, Jingying

    2012-12-01

    A highly sensitive amperometric sulfadiazine sensor based on coating multiwalled carbon nanotubes (MWCNTs) and N-octyl-pyridinium-hexafluorophosphate (OPPF(6)) ionic liquid composite on a glassy carbon (GC) electrode is described. The MWCNTs/OPPF(6) composite contributed new properties to electrochemical sensors by combining the advantages of both ionic liquids and MWCNTs. Compared with bare GC electrode, the electrocatalytic activity of MWCNTs/OPPF(6) generated a greatly improved electrochemical detection of sulfadiazine including low oxidation potential, high current responses, and good anti-fouling performance. The oxidation peak currents of sulfadiazine obtained on the MWCNTs/OPPF(6) coated GC electrode were proportional to the concentration of sulfadiazine within the range of 3.3-35.4 μM with a detection limit of 0.21 μM.

  9. Optimization of covalent immobilization of Trichoderma reesei cellulase onto modified ReliZyme HA403 and Sepabeads EC-EP supports for cellulose hydrolysis, in buffer and ionic liquids/buffer media.

    PubMed

    Bilgin, Ramazan; Yalcin, M Serkan; Yildirim, Deniz

    2016-08-01

    The covalent immobilization of Trichoderma reesei cellulase onto modified ReliZyme HA403 and Sepabeads EC-EP supports were carried out. The optimal immobilization conditions were determined using response surface methodology. The hydrolysis of cellulose using the free and immobilized cellulase preparations in ionic liquids (IL) using cosolvents was investigated. The hydrolytic activities in buffer medium containing 25% (v/v) of 1-butyl-3-methylimidazolium hexafluorophosphate were around 2.6-, 1.6-, and 5.5-fold higher than the activities in buffer medium. The retained initial activities were 32% and 57%, respectively for cellulase preparations immobilized onto Sepabeads EC-EP support and onto modified ReliZyme HA403 support after 5 reuses.

  10. Mixed ionic liquid as electrolyte for lithium batteries

    NASA Astrophysics Data System (ADS)

    Diaw, M.; Chagnes, A.; Carré, B.; Willmann, P.; Lemordant, D.

    Ionic liquids like 1-butyl-3-methylimidazolium tetrafluoroborate (IMIBF 4) or hexafluorophosphate (IMIPF 6) and 1-butyl-4-methylpyridinium tetrafluoroborate (PyBF 4) were mixed with organic solvents such as butyrolactone (BL) and acetonitrile (ACN). A lithium salt (LiBF 4 or LiPF 6) was added to these mixtures for possible application in the field of energy storage (batteries or supercapacitors). Viscosities, conductivities and electrochemical windows at a Pt electrode of these electrolytes were investigated. All studied electrolytes are stable toward oxidation and exhibit a vitreous phase transition, which has been determined by application of the VTF theory to conductivity measurements. Mixtures containing the BF 4- anion exhibit the lowest viscosity and the highest conductivity. Two mixtures have been optimized in terms of conductivity: BL/IMIBF 4 (60/40, v/v) and ACN/IMIBF 4 (70/30, v/v).

  11. Depth profiling the solid electrolyte interphase on lithium titanate (Li4Ti5O12) using synchrotron-based photoelectron spectroscopy

    NASA Astrophysics Data System (ADS)

    Nordh, Tim; Younesi, Reza; Brandell, Daniel; Edström, Kristina

    2015-10-01

    The presence of a surface layer on lithium titanate (Li4Ti5O12, LTO) anodes, which has been a topic of debate in scientific literature, is here investigated with tunable high surface sensitive synchrotron-based photoelectron spectroscopy (PES) to obtain a reliable depth profile of the interphase. Li||LTO cells with electrolytes consisting of 1 M lithium hexafluorophosphate dissolved in ethylene carbonate:diethyl carbonate (LiPF6 in EC:DEC) were cycled in two different voltage windows of 1.0-2.0 V and 1.4-2.0 V. LTO electrodes were characterized after 5 and 100 cycles. Also the pristine electrode as such, and an electrode soaked in the electrolyte were analyzed by varying the photon energies enabling depth profiling of the outermost surface layer. The main components of the surface layer were found to be ethers, P-O containing compounds, and lithium fluoride.

  12. Influence of carbon nanotubes on the optical properties of plasticized solid polymer electrolytes

    NASA Astrophysics Data System (ADS)

    Ibrahim, Suriani; Yasin, Siti Mariah Mohd; Johan, Mohd Rafie

    2013-07-01

    Polyethylene oxide (PEO) based solid polymer electrolyte films complexed with lithium hexafluorophosphate (LiPF6), ethylene carbonate (EC) and carbon nanotubes (CNTs) are prepared by solution-casting technique. The complexation of doping materials with polymer is confirmed by X-ray diffraction and infrared studies. The incorporation of LiPF6, EC and CNTs into the host polymer shows a significant increase in conductivity of 10-10 and 10-3 S cm-1. The optical properties such as direct and indirect band gaps are investigated for pure and doped polymer films within a wavelength range of 200-400 nm. It is found that the energy gaps and band edge values shift towards lower energies upon doping. It is shown that LiPF6, EC and CNTs are responsible for the formation of defects in polymer electrolytes, which increases the degree of disorder in the films.

  13. The Effect of Microporous Polymeric Support Modification on Surface and Gas Transport Properties of Supported Ionic Liquid Membranes

    PubMed Central

    Akhmetshina, Alsu A.; Davletbaeva, Ilsiya M.; Grebenschikova, Ekaterina S.; Sazanova, Tatyana S.; Petukhov, Anton N.; Atlaskin, Artem A.; Razov, Evgeny N.; Zaripov, Ilnaz I.; Martins, Carla F.; Neves, Luísa A.; Vorotyntsev, Ilya V.

    2015-01-01

    Microporous polymers based on anionic macroinitiator and toluene 2,4-diisocyanate were used as a support for 1-butyl-3-methylimidazolium hexafluorophosphate ([bmim][PF6]) and 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ([emim][Tf2N]) immobilization. The polymeric support was modified by using silica particles associated in oligomeric media, and the influence of the modifier used on the polymeric structure was studied. The supported ionic liquid membranes (SILMs) were tested for He, N2, NH3, H2S, and CO2 gas separation and ideal selectivities were calculated. The high values of ideal selectivity for ammonia-based systems with permanent gases were observed on polymer matrixes immobilized with [bmim][PF6] and [emim][Tf2N]. The modification of SILMs by nanosize silica particles leads to an increase of NH3 separation relatively to CO2 or H2S. PMID:26729177

  14. Factors influencing high voltage performance of coconut char derived carbon based electrical double layer capacitor made using acetonitrile and propylene carbonate based electrolytes

    NASA Astrophysics Data System (ADS)

    Hu, Changzheng; Qu, Weiguo; Rajagopalan, Ramakrishnan; Randall, Clive

    2014-12-01

    Symmetric EDLCs made using high purity carbon electrodes derived from coconut char were tested using 1 M Tetraethylammonium hexafluorophosphate dissolved in two different solvents namely acetonitrile and propylene carbonate. The cell voltage of the capacitor made using propylene carbonate can be extended to 3.5 V and it exhibited good cycling and thermal stability upto 70 °C while the voltage was limited to below 3.0 V in acetonitrile. XPS analysis of the positive and negative electrodes of EDLCs post cycling showed that the primary degradation products were related to ring opening reactions in propylene carbonate based electrolytes while water played a key role in degradation of acetonitrile based EDLCs.

  15. Physicochemical study of solution behavior of ionic liquid prevalent in diverse solvent systems at different temperatures

    NASA Astrophysics Data System (ADS)

    Datta, Biswajit; Roy, Mahendra Nath

    2016-11-01

    Electrolytic conductivity, density, viscosity and FTIR study of an ionic liquid, 1-butyl-4-methylpyridinium hexafluorophosphate ([bmpy]PF6) have been measured in diverse industrially significant solvents viz. acetonitrile, tetrahydrofuran and 1,3 dioxolane at various temperatures. In acetonitrile, the ion-pair formation of the IL was analyzed by Fuoss conductance equation. In Tetrahydrofuran and 1,3 Dioxolane systems, triple-ion formation analyzed by the Fuoss-Kraus theory. Ion-solvent interactions have been inferred in terms of limiting apparent molal volumes and viscosity B-coefficients. The results obtained from the experimental study, have been conferred in terms of ion-dipole interactions, structural aspect, configurational theory and solvatochromic effect.

  16. Temperature effects on the capacitance of an imidazolium-based ionic liquid on a graphite electrode: a molecular dynamics simulation.

    PubMed

    Liu, Xiaohong; Han, Yining; Yan, Tianying

    2014-08-25

    Temperature-dependent electric double layer (EDL) and differential capacitance-potential (C(d)-U) curves of the ionic liquid 1-butyl-3-methylimidazolium hexafluorophosphate (BMIM(+)/PF6(-)) were studied on a graphite electrode by molecular dynamics simulations. It was found that all C(d)-U curves were asymmetric camel-shaped with higher C(d) at negative polarization, attributed to the specific adsorption of BMIM(+). In addition, the maxima of Cd at the negative polarization decrease monotonically with temperature due to the thicker EDL, whereas at the positive polarization they gradually increase from 450 to 550 K and decrease at 600 K. Such temperature effects at positive polarization may be understood in terms of the competition between two aspects: the weakening specific adsorption of BMIM(+) allows more effective screening to the positive charge and overall increasing EDL thickness. Although the former dominates from 450 to 550 K, the latter becomes dominant at 600 K.

  17. Total chemical synthesis and chemotactic activity of human S100A12 (EN-RAGE).

    PubMed

    Miranda, L P; Tao, T; Jones, A; Chernushevich, I; Standing, K G; Geczy, C L; Alewood, P F

    2001-01-12

    Human S100A12 (extracellular newly identified RAGE (receptor for advanced glycosylation end products)-binding protein), a new member of the S100 family of EF-hand calcium-binding proteins, was chemically synthesised using highly optimised 2-(1H-benzotriazol-1-yl)-1,1,3,3-tetramethyluronium hexafluorophosphate/tert-butoxycarbonyl in situ neutralisation solid-phase chemistry. Circular dichroism studies indicated that CaCl(2) decreased the helical content by 27% whereas helicity was marginally increased by ZnCl(2). The propensity of S100A12 to dimerise was examined by electrospray ionisation time-of-flight mass spectrometry which clearly demonstrated the prevalence of the non-covalent homodimer (20890 Da). Importantly, synthetic human S100A12 in the nanomolar range was chemotactic for neutrophils and macrophages in vitro.

  18. 1,1'-[(1,3-Dihydroxypropane-2,2-diyl)dimethylene]dipyridinium bis-(hexa-fluoro-phosphate).

    PubMed

    Yuan, Ai-Lin; Zheng, Chun-Ling; Zhuang, Ling-Hua; Wang, Chang-Sheng; Wang, Guo-Wei

    2011-05-01

    The title compound, C(15)H(20)N(2)O(2) (2+)·2PF(6) (-), was prepared by anion exchange of two bromide ions in the ionic liquid 2,2'-bis-(pyridinium-1-ylmeth-yl)-propane-1,3-diol dibromide with potassium hexa-fluoro-phosphate. The two pyridine rings are planar (r.m.s. deviations = 0.008 and 0.00440 Å) and make a dihedral angle of 44.0 (2)°. Intermolecular O-H⋯F and C-H⋯F interactions occur. The four F atoms in each anion were refined as disordered over two sets of sites with an occupancy ration of 0.700 (19):0.300 (19).

  19. A multicolor photoinitiator for cationic polymerization and interpenetrated polymer network synthesis: 2,7-di-tert-butyldimethyldihydropyrene.

    PubMed

    Tehfe, Mohamad-Ali; Dumur, Frédéric; Vilà, Neus; Graff, Bernadette; Mayer, Cédric R; Fouassier, Jean Pierre; Gigmes, Didier; Lalevée, Jacques

    2013-07-12

    For polymer synthesis upon visible light, actual photoinitiator operates in a restricted part of the spectrum. As a consequence, several photoinitiators are necessary to harvest all of the emitted visible photons. Herein, 2,7-di-tert-butyldimethyldihydropyrene is used for the first time as a multicolor photoinitiator for the cationic polymerization of epoxides. Upon addition of diphenyliodonium hexafluorophosphate and optionally N-vinylcarbazole, the originality of this approach is to allow efficient monomer conversions under various excitation light sources in the 360-650 nm wavelength range: halogen lamps, and light-emitting and laser diodes. The synthesis of an interpenetrated polymer network from an epoxide/acrylate blend using a red light at 635 nm is also feasible. The formed polymer material exhibits a photochromic character.

  20. Theoretical investigation of polarization effects in solution: Importance of solvent collective motions

    SciTech Connect

    Ishida, Tateki

    2015-01-22

    Recent theoretical studies on interesting topics related to polarization effects in solutions are presented. As one of interesting topics, ionic liquids (ILs) solvents are focused on. The collective dynamics of electronic polarizability through interionic dynamics and the effect of polarization in ILs, 1-butyl-3-methylimidazolium hexafluorophosphate ([BMIm][PF{sub 6}]), are studied with molecular dynamics simulation. Also, the time-dependent polarization effect on the probe betaine dye molecule, pyridinium N-phenoxide, in water is investigated by a time-dependent reference interaction site model self-consistent field (time-dependent RISM-SCF) approach. The importance of considering polarization effects on solution systems related to solvent collective motions is shown.

  1. Theoretical investigation of polarization effects in solution: Importance of solvent collective motions

    NASA Astrophysics Data System (ADS)

    Ishida, Tateki

    2015-01-01

    Recent theoretical studies on interesting topics related to polarization effects in solutions are presented. As one of interesting topics, ionic liquids (ILs) solvents are focused on. The collective dynamics of electronic polarizability through interionic dynamics and the effect of polarization in ILs, 1-butyl-3-methylimidazolium hexafluorophosphate ([BMIm][PF6]), are studied with molecular dynamics simulation. Also, the time-dependent polarization effect on the probe betaine dye molecule, pyridinium N-phenoxide, in water is investigated by a time-dependent reference interaction site model self-consistent field (time-dependent RISM-SCF) approach. The importance of considering polarization effects on solution systems related to solvent collective motions is shown.

  2. Synthesis and Anchoring of Antineoplastic Ferrocene and Phthalocyanine Derivatives on Water-Soluble Polymeric Drug Carriers Derived from Lysine and Aspartic Acid

    PubMed Central

    Maree, M. David; Neuse, Eberhard W.; Erasmus, Elizabeth; Swarts, Jannie C.

    2008-01-01

    The general synthetic strategy towards water-soluble biodegradable drug carriers and the properties that they must have are discussed. The syntheses of water-soluble biodegradable copolymers of lysine and aspartic acid as potential drug-delivering devices, having amine-functionalised side chains are then described. Covalent anchoring of carboxylic acid derivatives of the antineoplastic ferrocene and photodynamically active phthalocyanine moieties to the amine-containing drug carrier copolymers under mild coupling conditions has been achieved utilising the coupling reagent O-benzotriazolyl-N,N,N′,N′-tetramethyluronium hexafluorophosphate to promote formation of the biodegradable amide bond. Even though the parent antineoplastic ferrocene and phthalocyanine derivatives are themselves insoluble in water at pH < 7, the new carrier-drug conjugates that were obtained are well water-soluble. PMID:18288243

  3. Electrochemical Investigation of Adsorption of Single-Wall Carbon Nanotubes at a Liquid/Liquid Interface.

    PubMed

    Rabiu, Aminu K; Toth, Peter S; Rodgers, Andrew N J; Dryfe, Robert A W

    2017-02-01

    There is much interest in understanding the interfacial properties of carbon nanotubes, particularly at water/oil interfaces. Here, the adsorption of single-wall carbon nanotubes (SWCNTs) at the water/1,2-dichloroethane (DCE) interface, and the subsequent investigation of the influence of the adsorbed nanotube layer on interfacial ion transfer, is studied by using the voltammetric transfer of tetramethylammonium (TMA(+)) and hexafluorophosphate (PF6(-)) as probe ions. The presence of the interfacial SWCNT layer significantly suppresses the transfer of both ions across the interface, with a greater degree of selectivity towards the PF6(-) ion. This effect was attributed both to the partial blocking of the interface by the SWCNTs and to the potential dependant adsorption of background electrolyte ions on the surface of the SWCNTs, as confirmed by X-ray photoelectron spectroscopy, which is caused by an electrostatic interaction between the interfacial SWCNTs and the transferring ion.

  4. Sensitive determination of Amaranth in drinks by highly dispersed CNT in graphene oxide "water" with the aid of small amounts of ionic liquid.

    PubMed

    Wang, Meiling; Sun, Yinlu; Yang, Xiongbo; Zhao, Jianwei

    2015-07-15

    Graphene oxide (GO) is a pH-dependent amphiphile. In this paper, it was found that carbon nanotubes (CNTs) can be highly dispersed in graphene oxide "water" with the aid of prototype ionic liquid of 1-butyl-3-methylimidazolium hexafluorophosphate ([BMIM][PF6]). The introduction of [BMIM][PF6] not only can minimize the defects of poor electrical conductivity of GO, but also can improve the dispersibility of CNT in water. Hence, a new composite of CNT/GO-[BMIM][PF6] with high dispersibility and strong conductivity was presented for the first time and employed in the sensitive determination of Amaranth in soft drinks. The detection limit achieved (0.1 nM) is much lower than the guideline values in soft drinks. The ease of preparation, low background current, high sensitivity and stability can create novel avenues and applications for fabricating robust sensors for determination of other azo dyes in foods.

  5. Anion Solvation in Carbonate-Based Electrolytes

    DOE PAGES

    von Wald Cresce, Arthur; Gobet, Mallory; Borodin, Oleg; ...

    2015-11-16

    The correlation between Li+ solvation and interphasial chemistry on anodes firmly established in Li-ion batteries, the effect of cation–solvent interaction has gone beyond bulk thermodynamic and transport properties and become an essential element that determines the reversibility of electrochemistry and kinetics of Li-ion intercalation chemistries. Now, most studies are dedicated to the solvation of Li+, and the solvation of anions in carbonate-based electrolytes and its possible effect on the electrochemical stability of such electrolytes remains little understood. Moreover, as a mirror effort to prior Li+ solvation studies, this work focuses on the interactions between carbonate-based solvents and two anions (hexafluorophosphate,more » PF6–, and tetrafluoroborate, BF4–) that are most frequently used in Li-ion batteries. The possible correlation between such interaction and the interphasial chemistry on cathode surface is also explored.« less

  6. The Effect of Microporous Polymeric Support Modification on Surface and Gas Transport Properties of Supported Ionic Liquid Membranes.

    PubMed

    Akhmetshina, Alsu A; Davletbaeva, Ilsiya M; Grebenschikova, Ekaterina S; Sazanova, Tatyana S; Petukhov, Anton N; Atlaskin, Artem A; Razov, Evgeny N; Zaripov, Ilnaz I; Martins, Carla F; Neves, Luísa A; Vorotyntsev, Ilya V

    2015-12-30

    Microporous polymers based on anionic macroinitiator and toluene 2,4-diisocyanate were used as a support for 1-butyl-3-methylimidazolium hexafluorophosphate ([bmim][PF₆]) and 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ([emim][Tf₂N]) immobilization. The polymeric support was modified by using silica particles associated in oligomeric media, and the influence of the modifier used on the polymeric structure was studied. The supported ionic liquid membranes (SILMs) were tested for He, N₂, NH₃, H₂S, and CO₂ gas separation and ideal selectivities were calculated. The high values of ideal selectivity for ammonia-based systems with permanent gases were observed on polymer matrixes immobilized with [bmim][PF₆] and [emim][Tf₂N]. The modification of SILMs by nanosize silica particles leads to an increase of NH₃ separation relatively to CO₂ or H₂S.

  7. Ultrasound-assisted ionic liquid-based dispersive liquid-liquid microextraction for preconcentration of patent blue V and its determination in food samples by UV-visible spectrophotometry.

    PubMed

    Unsal, Yunus Emre; Soylak, Mustafa; Tuzen, Mustafa

    2015-04-01

    Ultrasound-assisted ionic liquid-based dispersive liquid-liquid microextraction procedure (UA-IL-DLLME) was developed for determination of trace levels of patent blue V prior to its determination by UV-visible spectrophotometry. Patent blue V was extracted from 25-mL sample into a 100-μL volume of ionic liquid, 1-butyl-3-methylimidazolium hexafluorophosphate ([bmim][PF6]), with the aid of sonication in an ultrasonic bath. Several variables affecting microextraction efficiency were optimized. Under the optimum experimental conditions, the detection limit (3 s) was 0.68 μg L(-1), and the preconcentration factor was 100. The relative standard deviation for six replicate determinations of patent blue V was 4.5%. The method was applied to the determination of patent blue V in food samples. The proposed procedure is effective, very simple, and fast.

  8. The self-assembled Ru(bpy)3(PF6)2 nanoparticle on polystyrene microfibers and its application for ECL sensing.

    PubMed

    Luo, Jiaojiao; Zhou, Cuisong; Shi, Yalin; Zhang, Lei; Xiao, Dan

    2013-10-21

    Ruthenium nanoparticle tris(2,2'-bipyridyl)ruthenium(II) bis(hexafluorophosphate) (Ru(bpy)3(PF6)2, RuNP) was self-assembled on polystyrene (PS) electrospun microfibers. The formation of RuNP is attributed to the sulfonated PS (SPS) microfibers' high adsorptive capability of 94% for Ru(bpy)3(2+), as well as the strong interaction between the Ru(bpy)3(2+) and ionic liquid (1-butyl-3-methylimidazolium hexafluorophosphate, BMIMPF6). The RuNP/SPS microfibers exhibited an enhanced electrochemiluminescence (ECL) emission, 2.3 times higher than that from Ru(bpy)3(2+)/SPS microfibers and 6.6 times higher than that from Ru(bpy)3(2+)/SPS continuous thin films. It is worthy of note that, as a result of the hydrophobic nature of the RuNP, the transfer of water-insoluble α-naphthol is accelerated, and thus the α-naphthol ECL quenching efficiency is enhanced. An ECL sensor based on the RuNP/SPS microfibers was fabricated and used to detect low concentrations of α-naphthol. The detection limit was of 1.0 nM (S/N > 3), and the linear response ranged from 0 to 18 μM. This sensor has been successfully applied to measure the α-naphthol content in pesticide carbaryl samples. Our work provides a very simple and cost-effective method to fabricate RuNP on polymer microfibers with great potential in the field of chemo/biosensors.

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

    PubMed

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

    2006-05-19

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

  10. New solvents designed on the basis of the molecular-microscopic properties of binary mixtures of the type (protic molecular solvent + 1-butyl-3-methylimidazolium-based ionic liquid).

    PubMed

    Fortunato, Graciela G; Mancini, Pedro M; Bravo, M Virginia; Adam, Claudia G

    2010-09-16

    The main purpose of this work is to analyze the microscopic feature of solvent systems resulting from the basis of binary mixtures formed by a protic molecular solvent (methanol, ethanol, propan-1-ol, propan-2-ol, and 2-ethoxyethanol) and a 1-butyl-3-methylimidazolium (bmim)-based ionic liquid (IL) cosolvent composed of different anions (tetrafluoroborate, hexafluorophosphate, chloride, and bromide). At the same time, a complementary aim is to evaluate the incidence of anion type on the solvation pattern. The empirical solvatochromic parameters E(T)(N), π*, β, and α were determined from the UV-vis solvatochromic shifts of adequate probes. The behavior of the solvent systems was analyzed according to their deviation from ideality. E(T)(N) polarity and π* dipolarity/polarizability exhibit positive deviation from ideal behavior in all binary mixtures at the explored compositions. Moreover, E(T)(N) and α parameters display synergetic effects in some binary mixtures composed of tetrafluoroborate and hexafluorophosphate anions. The influence of anion nature on the response patterns is clearly manifested in the basicity β and acidity α of the media. This is connected with the degree and type of interaction between the anions and the 1-butyl-3-methylimidazolium cation. The ion-pair character of the ionic liquids affects their interactions with a solute or a molecular solvent. The application of an appropriate preferential solvation model allowed us to obtain valuable information about solute-solvent and solvent-solvent interactions of the selected ionic liquid mixtures. It is possible to identify relevant mixtures paying particular attention to the most remarkable microscopic properties, the acidity and the basicity, in order to propose "new solvents". Thus, the solvating feature can be tailored selecting the molecular and/or the ionic component at a particular composition. A simplified combined nearly ideal binary solvent/Redlich-Kister (CNIBS/R-K) equation is

  11. In situ metathesis reaction combined with liquid-phase microextraction based on the solidification of sedimentary ionic liquids for the determination of pyrethroid insecticides in water samples.

    PubMed

    Hu, Lu; Zhang, Panjie; Shan, Wanyu; Wang, Xuan; Li, Songqing; Zhou, Wenfeng; Gao, Haixiang

    2015-11-01

    A novel dispersion liquid-liquid microextraction method based on the solidification of sedimentary ionic liquids (SSIL-DLLME), in which an in situ metathesis reaction forms an ionic liquid (IL) extraction phase, was developed to determine four pyrethroid insecticides (i.e., permethrin, cyhalothrin, fenpropathrin, and transfluthrin) in water followed by separation using high-performance liquid chromatography. In the developed method, in situ DLLME was used to enhance the extraction efficiency and yield. After centrifugation, the extraction solvent, tributyldodecylphosphonium hexafluorophosphate ([P44412][PF6]), was easily collected by solidification in the bottom of the tube. The effects of various experimental parameters, the quantity of tributyldodecylphosphonium bromide ([P44412]Br), the molar ratio of [P44412]Br to potassium hexafluorophosphate (KPF6), the ionic strength, the temperature of the sample solution, and the centrifugation time, were optimized using a Plackett-Burman design to identify the significant factors that affected the extraction efficiency. These significant factors were then optimized using a central composite design. Under the optimized conditions, the recoveries of the four pyrethroid insecticides at four spiked levels ranged from 87.1% to 101.7%, with relative standard deviations (RSDs) ranging from 0.1% to 5.5%. At concentration levels between 1 and 500 µg/L, good linearity was obtained, with coefficients of determination greater than 0.9995. The limits of detection (LODs) for the four pyrethroid insecticides were in the range of 0.71-1.54 µg/L. The developed method was then successfully used for the determination of pyrethroid insecticides in environmental samples.

  12. A novel electrochemical immunosensor based on magnetosomes for detection of staphylococcal enterotoxin B in milk.

    PubMed

    Wu, Longyun; Gao, Bo; Zhang, Fang; Sun, Xiulan; Zhang, Yinzhi; Li, Zaijun

    2013-03-15

    In this paper, a novel electrochemical immunosensor to detect staphylococcal enterotoxin B based on bio-magnetosomes, polyaniline nano-gold composite and 1,2-dimethyl-3-butylimidazolium hexafluorophosphate ionic liquid, was developed, and found to exhibit high sensitivity and stability. The specific antibody to staphylococcal enterotoxin B conjugated with the magnetosomes showed rapid immunoreactions and good dispersion, which contributed to the formation of a nanostructurally smooth and dense film on the surface of a gold electrode. Polyaniline nano-gold composite and 1,2-dimethyl-3-butylimidazolium hexafluorophosphate ionic liquid were used to modify the electrode as mediators to improve the electron transfer and offer an excellent biocompatible microenvironment for the antibody to retain its activity to enhance the response of the electrochemical sensor. Under optimal conditions, the developed immunosensor showed a good linear response in the range from 0.05 to 5 ng/mL (R(2)=0.9957) with a detection limit as low as 0.017 ng/mL, compared with the one without magnetosomes (0.05-5 ng/mL, 0.033 ng/mL), this developed immunosensor showed a wider response range and a reduced detection limit. And a good specificity with little adsorption to staphylococcal enterotoxin A, C and Na(+), K(+), Ca(2+) was obtained. Moreover, the immunosensor exhibited a good long-time stability at 4 °C reaching up to 60 days, which showed a relatively long working life. Meanwhile the immunosensor could be regenerated four times using NaOH elution. The sensor also displayed a good repeatability with a relative standard deviation of 5.02% for staphylococcal enterotoxin B detection (1 ng/mL, n=9). Furthermore, high recoveries in milk samples from 81% to 118% were achieved and successfully applied to milk sample detection. The obtained results demonstrate that the developed electrochemical immunosensor is a promising tool for the detection of staphylococcal enterotoxin B in food.

  13. Electrochemical Characterization and Catalytic Application of Gold-Supported Ferrocene-Containing Diblock Copolymer Thin Films in Ethanol Solution

    DOE PAGES

    Ghimire, Govinda; Coceancigh, Herman; Yi, Yi; ...

    2017-01-25

    This study reports the electrochemical behavior and catalytic property of electrode-supported thin films of polystyrene-block-poly(2-(acryloyloxy)ethyl ferrocenecarboxylate) (PS-b-PAEFc) in an ethanol (EtOH) solution. The electrochemical properties of PS-b-PAEFc films with different PAEFc volume fractions (fPAEFc = 0.47, 0.30, and 0.17) in 0.1 M ethanolic sodium hexafluorophosphate were compared with those in an acetonitrile (MeCN) solution of 0.1 M tetrabutylammonium hexafluorophosphate. Pristine PS-b-PAEFc films did not afford significant faradaic currents in the EtOH solution because EtOH is a nonsolvent for both PS and PAEFc. However, the films could be rendered redox-active in the EtOH solution by applying potentials in the MeCN solutionmore » to induce the redox-associated incorporation of the supporting electrolytes into the films. Atomic force microscopy images verified the stability of PAEFc microdomains upon electrochemical measurements in these solutions. Cyclic voltammograms measured in the EtOH solution for PS-b-PAEFc with the larger fPAEFc were diffusion-controlled regardless of ellipsometric film thickness (23 – 152 nm) at relatively slow scan rates, in contrast to those in the MeCN solution that were controlled by surface-confined redox species. The electron propagation efficiency in the EtOH solution was significantly lower than that in the MeCN solution due to the poorer swelling of the films, which limited the migration of counter ions and the collisional motions of the ferrocene moieties. PS-b-PAEFc films were applied as electrochemically-responsive heterogeneous catalysts based on the ferrocenium moieties for Michael addition reaction between methyl vinyl ketone and ethyl 2-oxocyclopentanecarboxylate (E2OC) in 0.1 M NaPF6/EtOH. The catalytic activities of thin films were similar regardless of fPAEFc, suggesting that the catalytic reaction took place for the reactants that could penetrate through the film and reach PAEFc microdomains

  14. Degradable polymeric nanoparticles by aggregation of thermoresponsive polymers and ``click'' chemistry

    NASA Astrophysics Data System (ADS)

    Dworak, Andrzej; Lipowska, Daria; Szweda, Dawid; Suwinski, Jerzy; Trzebicka, Barbara; Szweda, Roza

    2015-10-01

    This study describes a novel approach to the preparation of crosslinked polymeric nanoparticles of controlled sizes that can be degraded under basic conditions. For this purpose thermoresponsive copolymers containing azide and alkyne functions were obtained by ATRP of di(ethylene glycol) monomethyl ether methacrylate (D) and 2-aminoethyl methacrylate (A) followed by post polymerization modification. The amino groups of A were reacted with propargyl chloroformate or 2-azido-1,3-dimethylimidazolinium hexafluorophosphate, which led to two types of copolymers. Increasing the temperature of aqueous solutions of the mixed copolymers caused their aggregation into spherical nanoparticles composed of both types of chains. Their dimensions could be controlled by changing the concentration and heating rate of the solutions. Covalent stabilization of aggregated chains was performed by a ``click'' reaction between the azide and alkyne groups. Due to the presence of a carbamate bond the nanoparticles undergo pH dependent degradation under mild basic conditions. The proposed procedure opens a route to new carriers for the controlled release of active species.This study describes a novel approach to the preparation of crosslinked polymeric nanoparticles of controlled sizes that can be degraded under basic conditions. For this purpose thermoresponsive copolymers containing azide and alkyne functions were obtained by ATRP of di(ethylene glycol) monomethyl ether methacrylate (D) and 2-aminoethyl methacrylate (A) followed by post polymerization modification. The amino groups of A were reacted with propargyl chloroformate or 2-azido-1,3-dimethylimidazolinium hexafluorophosphate, which led to two types of copolymers. Increasing the temperature of aqueous solutions of the mixed copolymers caused their aggregation into spherical nanoparticles composed of both types of chains. Their dimensions could be controlled by changing the concentration and heating rate of the solutions. Covalent

  15. Electrochemical characterization and catalytic application of gold-supported ferrocene-containing diblock copolymer thin films in ethanol solution

    SciTech Connect

    Ghimire, Govinda; Coceancigh, Herman; Yi, Yi; Ito, Takashi

    2016-12-26

    This study reports the electrochemical behavior and catalytic property of electrode-supported thin films of polystyrene-block-poly(2-(acryloyloxy)ethyl ferrocenecarboxylate) (PS-b-PAEFc) in an ethanol (EtOH) solution. The electrochemical properties of PS-b-PAEFc films with different PAEFc volume fractions (fPAEFc = 0.47, 0.30, and 0.17) in 0.1 M ethanolic sodium hexafluorophosphate were compared with those in an acetonitrile (MeCN) solution of 0.1 M tetrabutylammonium hexafluorophosphate. Pristine PS-b-PAEFc films did not afford significant faradaic currents in the EtOH solution because EtOH is a nonsolvent for both PS and PAEFc. However, the films could be rendered redox-active in the EtOH solution by applying potentials in the MeCN solution to induce the redox-associated incorporation of the supporting electrolytes into the films. Atomic force microscopy images verified the stability of PAEFc microdomains upon electrochemical measurements in these solutions. Cyclic voltammograms measured in the EtOH solution for PS-b-PAEFc with the larger fPAEFc were diffusion-controlled regardless of ellipsometric film thickness (23 – 152 nm) at relatively slow scan rates, in contrast to those in the MeCN solution that were controlled by surface-confined redox species. The electron propagation efficiency in the EtOH solution was significantly lower than that in the MeCN solution due to the poorer swelling of the films, which limited the migration of counter ions and the collisional motions of the ferrocene moieties. PS-b-PAEFc films were applied as electrochemically-responsive heterogeneous catalysts based on the ferrocenium moieties for Michael addition reaction between methyl vinyl ketone and ethyl 2-oxocyclopentanecarboxylate (E2OC) in 0.1 M NaPF6/EtOH. The catalytic activities of thin films were similar regardless of fPAEFc, suggesting that the catalytic reaction took place for the

  16. Influence of the counteranion on the ability of 1-dodecyl-3-methyltriazolium ionic liquids to form mesophases

    DOE PAGES

    Stappert, Kathrin; Unal, Derya; Spielberg, Eike T.; ...

    2014-11-25

    The influence of the counteranion on the ability of the mesogenic cation 1-methyl-3-dodecyl-triazolium to form mesophases is explored. To that avail, salts of the cation with anions of different size, shape, and hydrogen bonding capability such as Cl–, Br–, I–, I3–, PF6–, and Tf2N– [bis(trifluorosulfonyl)amide] were synthesized and characterized. The crystal structures of the bromide, the iodide, and the triiodide reveal that the cations form bilayers with cations oriented in opposite directions featuring interdigitated alkyl tails. Within the layers, the cations are separated by anions. The rod-shaped triiodide anion forces the triazolium cation to align with it in this crystalmore » structure but due to its space requirement reduces the alkyl chain interdigitation which prevents the formation of a mesophase. Rather the compound transforms directly from a crystalline solid to an (ionic) liquid like the analogous bis(trifluorosulfonyl)amide. In contrast, the simple halides and the hexafluorophosphate form liquid crystalline phases. As a result, their clearing points shift with increasing anion radius to lower temperatures.« less

  17. A High Molar Extinction Coefficient Bisterpyridyl Homoleptic Ru(II) Complex with trans-2-Methyl-2-butenoic Acid Functionality: Potential Dye for Dye-Sensitized Solar Cells

    PubMed Central

    Adeloye, Adewale O.; Olomola, Temitope O.; Adebayo, Akinbulu I.; Ajibade, Peter A.

    2012-01-01

    In our continued efforts in the synthesis of ruthenium(II) polypyridine complexes as potential dyes for use in varied applications, such as the dye-sensitized solar cells (DSSCs), this work particularly describes the synthesis, absorption spectrum, redox behavior and luminescence properties of a new homoleptic ruthenium(II) complex bearing a simple trans-2-methyl-2-butenoic acid functionality as the anchoring ligand on terpyridine moiety. The functionalized terpyridine ligand: 4′-(trans-2-methyl-2-butenoic acid)-terpyridyl (L1) was synthesized by aryl bromide substitution on terpyridine in a basic reaction condition under palladium carbide catalysis. In particular, the photophysical and redox properties of the complex formulated as: bis-4′-(trans-2-methyl-2-butenoic acid)-terpyridyl ruthenium(II) bis-hexafluorophosphate [Ru(L1)2(PF6)2] are significantly better compared to those of [Ru(tpy)2]2+ and compare well with those of the best emitters of Ru(II) polypyridine family containing tridentate ligands. Reasons for the improved photophysical and redox properties of the complex may be attributed partly to the presence of a substituted α,β-unsaturated carboxylic acid moiety leading to increase in the length of π-conjugation bond thereby enhancing the MLCT-MC (Metal-to-ligand-charge transfer-metal centred) energy gap, and to the reduced difference between the minima of the excited and ground states potential energy surfaces. PMID:22489165

  18. Where is the lithium? Quantitative determination of the lithium distribution in lithium ion battery cells: Investigations on the influence of the temperature, the C-rate and the cell type

    NASA Astrophysics Data System (ADS)

    Vortmann-Westhoven, Britta; Winter, Martin; Nowak, Sascha

    2017-04-01

    With lithium being the capacity determining species in lithium-ion battery (LIB) cells, the local quantification is of enormous importance for understanding of the cell performance. The investigation of the lithium distribution in LIB full cells is performed with two different cell types, T-cells of the Swagelok® type and pouch bag cells with lithium nickel cobalt manganese oxide and mesocarbon microbead graphite as the active materials as well as a lithium hexafluorophosphate based organic carbonate solvent electrolyte. The lithium content of/at the individual components of the cells is analyzed for different states of charge (SOCs) by inductively coupled plasma-optical emission spectrometry (ICP-OES) and the lithium distribution as well as the loss of active lithium within the cells is calculated after cycling. With increasing the SOC, the lithium contents decrease in the cathodes and simultaneously increase in the anodes. The temperature increase shows a clear shift of the lithium content in the direction of the anode for the T-cells. The comparison of the C-rate influence shows that the lower the C-rate, the more the lithium content on the electrodes is shifted into the direction of the anode.

  19. Synthesis of gold nanoparticles by laser ablation of an Au foil inside and outside ionic liquids.

    PubMed

    Wender, Heberton; Andreazza, Marcos L; Correia, Ricardo R B; Teixeira, Sérgio R; Dupont, Jairton

    2011-03-01

    Stable gold nanoparticles (AuNPs) were prepared by simple laser ablation of an Au foil placed inside or outside four ionic liquids (ILs), without the addition of any external chemical reagent. Irregular spherical AuNPs with a diameter range of 5 to 20 nm were produced after laser ablation of an Au foil located inside or outside the ILs 1-n-butyl-3-methylimidazolium tetrafluoroborate (BMI·BF4), 1-n-butyl-3-methylimidazolium hexafluorophosphate (BMI·PF6) and 1-(3-cyanopropyl)-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ((BCN)MI·NTf2). Additionally, whereas laser ablation inside the IL 1-n-butyl-3-methylimidazolium dicyanamide BMI·N(CN)2 produced flower-like shaped nanoparticles of about 50 nm in size, ablation outside this IL presented similar results to the others ILs studied, as determined by TEM and UV-Vis. The size and shape of the prepared NPs were related to where NP nucleation and growth occurred, i.e., at the IL surface or within the IL. Indeed, the chemical composition of the IL/air interface and surface ion orientation played important roles in the stabilization of the AuNPs formed by laser ablation outside the ILs.

  20. Superior Electrocatalytic Activity of a Robust Carbon-Felt Electrode with Oxygen-Rich Phosphate Groups for All-Vanadium Redox Flow Batteries.

    PubMed

    Kim, Ki Jae; Lee, Heon Seong; Kim, Jeonghun; Park, Min-Sik; Kim, Jung Ho; Kim, Young-Jun; Skyllas-Kazacos, Maria

    2016-06-08

    A newly prepared type of carbon felt with oxygen-rich phosphate groups is proposed as a promising electrode with good stability for all-vanadium redox flow batteries (VRFBs). Through direct surface modification with ammonium hexafluorophosphate (NH4 PF6 ), phosphorus can be successfully incorporated onto the surface of the carbon felt by forming phosphate functional groups with -OH chemical moieties that exhibit good hydrophilicity. The electrochemical reactivity of the carbon felt toward the redox reactions of VO(2+) /VO2 (+) (in the catholyte) and V(3+) /V(2+) (in the anolyte) can be effectively improved owing to the superior catalytic effects of the oxygen-rich phosphate groups. Furthermore, undesirable hydrogen evolution can be suppressed by minimizing the overpotential for the V(3+) /V(2+) redox reaction in the anolyte of the VRFB. Cell-cycling tests with the catalyzed electrodes show improved energy efficiencies of 88.2 and 87.2 % in the 1(st) and 20(th)  cycles compared with 83.0 and 81.1 %, respectively, for the pristine electrodes at a constant current density of 32 mA cm(-2) . These improvements are mainly attributed to the faster charge transfer allowed by the integration of the oxygen-rich phosphate groups on the carbon-felt electrode.

  1. Electrochemical characterization of sub-micro-gram amounts of organic semiconductors using scanning droplet cell microscopy.

    PubMed

    Gasiorowski, Jacek; Mardare, Andrei I; Sariciftci, Niyazi S; Hassel, Achim Walter

    2013-02-15

    Scanning droplet cell microscopy (SDCM) uses a very small electrolyte droplet at the tip of a capillary which comes in contact with the working electrode. This method is particularly interesting for studies on organic semiconductors since it provides localized electrochemical investigations with high reproducibility. One clear advantage of applying SDCM is represented by the very small amounts of material necessary (less than 1 mg). Organic materials can be investigated quickly and inexpensively in electrochemical studies with a high throughput. In the present study, thin layers of poly(3-hexylthiophene) (P3HT), which is one of the most often used material for organic solar cells, were deposited on ITO/glass as working electrodes in SDCM studies. The redox reactions in 0.1 M tetra(n-butyl)ammonium hexafluorophosphate (TBAPF6) dissolved in propylene carbonate were studied by cyclic voltammetry and by electrochemical impedance spectroscopy. Two reversible, distinct oxidation steps of the P3HT were detected and their kinetics were studied in detail. The doping of P3HT increased due to the electrochemical oxidation and had resulted in a decrease of the film resistance by a few orders of magnitude. Due to localization on the sample various parameter combinations can be studied quantitatively and reproducibly.

  2. Study on characteristics of PVDF/nano-clay composite polymer electrolyte using PVP as pore-forming agent

    SciTech Connect

    Dyartanti, Endah R. E-mail: endah-rd@uns.ac.id; Purwanto, Agus; Widiasa, I. Nyoman; Susanto, Heru E-mail: endah-rd@uns.ac.id

    2016-02-08

    Polyvinylidene fluoride (PVDF) based polymer electrolytes have a high dielectric constant, which can assist in greater ionization of lithium salts. The main advantages of PVDF are its durability in long battery operation and its ability to be a good ion conductor. However, the limitation of this polymer is its crystalline molecular structure. Dispersing nano-particles in the polymer matrix may improve the characteristics of the PVDF polymer. This paper aims to investigate the impact of nano-clay addition on the characteristics of PVDF polymer to be used as a polymer electrolyte membrane. In addition, the effect of poly(vinyl pyrrolidone) (PVP) is also investigated. The membrane was prepared by phase separation method whereas the polymer electrolyte membranes was prepared by immersing into 1 M lithium hexafluorophosphate (LiPF{sub 6}) in ethylene carbonate/dimethyl carbonate (EC/DMC) electrolytes for 1 h. The membranes were characterized by scanning electron microscope (SEM), porosity and electrolyte uptake and performance in battery cell. The results showed that both nano-clay and PVP have significant impacts on the improvement of PVDF membranes to be used as polymer electrolyte.

  3. Ultrasound-assisted temperature-controlled ionic liquid emulsification microextraction coupled with capillary electrophoresis for the determination of parabens in personal care products.

    PubMed

    Ma, Teng; Li, Zheng; Jia, Qiong; Zhou, Weihong

    2016-07-01

    We developed a CE and ultrasound-assisted temperature-controlled ionic liquid emulsification microextraction method for the determination of four parabens (methyl paraben, ethyl paraben, propyl paraben, and butyl paraben) in personal care products including mouthwash and toning lotion. In the proposed extraction procedure, ionic liquid (IL, 1-octyl-3-methylimidazolium hexafluorophosphate) was used as extraction solvent, moreover, no disperser solvent was needed. Parameters affecting the extraction efficiency including volume of IL, heating temperature, ultrasonic time, extraction time, sample pH, ionic strength, and centrifugation time were optimized. Under the optimized conditions, the method was found to be linear over the range of 3-500 ng/mL with coefficient of determination (R(2) ) in the range of 0.9990-0.9998. The LODs and LOQs for the four parabens were 0.45-0.72 ng/mL and 1.50-2.40 ng/mL, respectively. Intraday and interday precisions (RSDs, n = 5) were in the range of 5.4-6.8% and 7.0-8.7%, respectively. The recoveries of parabens at different spiked levels ranged from 71.9 to 119.2% with RSDs less than 9.5%.

  4. The glass-liquid transition of water on hydrophobic surfaces.

    PubMed

    Souda, Ryutaro

    2008-09-28

    Interactions of thin water films with surfaces of graphite and vitrified room-temperature ionic liquid [1-butyl-3-methylimidazolium hexafluorophosphate ([bmim][PF(6)])] were investigated using time-of-flight secondary ion mass spectrometry as a function of temperature and annealing time to elucidate the glass-liquid transition of water at the molecular level. Surface diffusion of water occurs at temperatures higher than 120 K, thereby forming three-dimensional clusters (a two-dimensional layer) on the [bmim][PF(6)] (graphite) surface. The hydrophobic effect of the surface decreases with increasing coverage of water; the bulklike properties evolve up to 40 ML, as evidenced by the occurrence of film dewetting at around the conventional glass transition temperature (140 K). Results also showed that aging is necessary for the water monolayer (a 40 ML water film) to dewet the graphite ([bmim][PF(6)]) surface. The occurrence of aging is explainable by the successive evolution of two distinct liquids during the glass-liquid transition: low density liquid is followed by supercooled liquid water. The water monolayer on graphite is characterized by the preferred orientation of unpaired OH groups toward the surface; this structure is arrested during the aging time despite the occurrence of surface diffusion. However, the water monolayer formed on the [bmim][PF(6)] surface agglomerates immediately after the commencement of surface diffusion. The structure of low density liquid tends to be arrested by the attractive interaction with the neighbors.

  5. Electrochemical properties of imidazolium salt electrolytes for electrochemical capacitor applications

    SciTech Connect

    McEwen, A.B.; Ngo, H.L.; LeCompte, K.; Goldman, J.L.

    1999-05-01

    The specific ionic conductivity, dynamic viscosity, and electrochemical stability of several imidazolium salts are reported as neat ionic liquids and their solutions in several organic solvents. The temperature dependence of conductivity and viscosity are analyzed for 1-ethyl-3-methylimidazolium (EMI{sup +}) and 1,2-dimethyl-3-n-propylimidazolium (DMPI{sup +}) salts, and the influence of the anions bis(trifluoromethylsulfonyl)imide (Im{sup {minus}}), bis(perfluoroethylsulfonyl)imide (Beti{sup {minus}}), hexafluoroarsenate (AsF{sub 6}{sup {minus}}), hexafluorophosphate (PF{sub 6}{sup {minus}}), and tetrafluoroborate (BF{sub 4}{sup {minus}}) on these properties are discussed. These imidazolium salts make possible electrolytes with high concentration (>3 M), high room temperature conductivity (up to 60 mS/cm), and a wide window of stability (>4 V at 20 {micro}A/cm{sup 2}). Differential scanning calorimetric results confirm a large glass phase for the ionic liquids, with substantial (>80 C) supercooling. Thermal gravimetric results indicate the imidazolium salts with Im{sup {minus}} and Beti{sup {minus}} anions to be thermally more stable than the lithium salt analogs. The Vogel-Tammann-Fulcher interpretation accurately describes the conductivity temperature dependence.

  6. Use of paired, bonded NdFeB magnets in redox magnetohydrodynamics.

    PubMed

    Arumugam, Prabhu U; Clark, Emily A; Fritsch, Ingrid

    2005-02-15

    Bonded neodymium-iron-boron (NdFeB) permanent magnets in a paired configuration were successfully used to control mass transport in redox-based, magnetohydrodynamics (MHD). Control of fluid flow based on magnetic fields has potential for use in portable lab-on-a-chip (LOAC) and analytical devices. Bonded magnets, composed of magnetic powder and organic binder materials, are less expensive and easier to fabricate and pattern than electromagnets and sintered permanent magnets, which have been previously used in MHD studies on electrochemical systems. The ability to pattern bonded magnets near and around the electrodes is expected to allow for better control over the magnetic field distribution and solution flow. Current was generated at an 800-microm-radius platinum disk electrode in a solution of 0.06 M nitrobenzene and 0.5 M tetra-n-butylammonium hexafluorophosphate in acetonitrile. Increases in limiting current in the presence of the magnetic field, which indicate enhancement in mass transport, for sintered (210+/-14%, N = 4, where B(r) = 1.23 T and magnetic field strength is 0.55 T) and bonded (94+/-8%, N = 4, where B(r) = 0.41 T and magnetic field strength is 0.20 T) magnets, were similar to those obtained using an electromagnet with the same magnetic flux densities. The magnetic field strength and not the magnet type is important in controlling fluid flow, which is encouraging for integration of bonded permanent magnets into LOAC devices.

  7. Photophysics of a ruthenium 4H-imidazole panchromatic dye in interaction with titanium dioxide.

    PubMed

    Schindler, Julian; Kupfer, Stephan; Wächtler, Maria; Guthmuller, Julien; Rau, Sven; Dietzek, Benjamin

    2015-04-07

    The photophysics of bis(4,4'-di-tert-butyl-2,2'-bipyridine-κ(2)N,N')[2-(4-carboxyphenyl)-4,5-bis(p-tolylimino-κN)imidazolato]ruthenium(II) hexafluorophosphate is investigated, both in solution and attached to a nanocrystalline TiO2 film. The studied substitution pattern of the 4H-imidazole ligand is observed to block a photoinduced structural reorganization pathway within the 4H-imidazole ligand that has been previously investigated. Protonation at the 4H-imidazole ring decreases the excited-state lifetime in solution. When the unprotonated dye is anchored to TiO2, photoinduced electron injection occurs from thermally nonrelaxed triplet metal-to-ligand charge transfer ((3)MLCT) states with a characteristic time constant of 0.5 ps and an injection efficiency of roughly 25%. Electron injection from the subsequently populated thermalized (3)MLCT state of the dye does not take place. The energy of this state seems to be lower than the conduction band edge of TiO2.

  8. Preparation of porous aromatic framework/ionic liquid hybrid composite coated solid-phase microextraction fibers and their application in the determination of organochlorine pesticides combined with GC-ECD detection.

    PubMed

    Wu, Mingxue; Chen, Gang; Liu, Ping; Zhou, Weihong; Jia, Qiong

    2016-01-07

    A novel hybrid material incorporating porous aromatic frameworks and an ionic liquid, 1-(triethoxy silyl)propyl-3-aminopropyl imidazole hexafluorophosphate, was prepared as solid-phase microextraction coating and employed for the extraction of organochlorine pesticides. Combining the advantages of porous aromatic frameworks and an ionic liquid, the fiber exhibited a high adsorption capacity for organochlorine pesticides. Under optimized experimental conditions, enhancement factors of 247-1696 were obtained with good linearity in the range of 1-500 μg L(-1). The detection limits and quantification limits were determined to be in the range of 0.11-0.29 μg L(-1) and 0.35-0.93 μg L(-1). The relative standard deviations for six replicates of organochlorine pesticides were in the range of 4.4%-7.2% and 5.7%-10.1% for one fiber and fiber-to-fiber, respectively. By coupling with a gas chromatography-electron capture detector, the novel fiber was successfully used for the determination of organochlorine pesticides in juice and milk samples with recoveries of 76.1%-121.3%.

  9. Ionic liquids for improving the extraction of NSAIDs in water samples using dispersive liquid-liquid microextraction by high performance liquid chromatography-diode array-fluorescence detection.

    PubMed

    Toledo-Neira, Carla; Álvarez-Lueje, Alejandro

    2015-03-01

    A rapid, sensitive and efficient analytical method based on the use of ionic liquids for determination of non-steroidal anti-inflammatory drugs (NSAIDs) in water samples was developed. High-performance liquid chromatography equipped with a diode array and fluorescence detector was used for quantification of ketoprofen, ibuprofen and diclofenac in tap and river water samples. This new method relies on the use of two ionic liquids with multiple functionalities: one functions as an extraction solvent (1-butyl-3-methylimidazolium hexafluorophosphate ([BMIM][PF6]), and the other changes the polarity in the aqueous medium (1-butyl-3-methylimidazolium tetrafluoroborate, ([BMIM][BF4]). Factors such as the type and volume of the ILs and dispersive solvent, sample volume, and centrifugation time were investigated and optimized. The optimized method exhibited good precision, with relative standard deviation values between 2% and 3%, for the three NSAIDs. Limits of detection achieved for all of the analytes were between 17 and 95 ng mL(-1), and the recoveries ranged from 89% to 103%. Furthermore, the enrichment factors ranged from 49 to 57. The proposed method was successfully applied to the analysis of NSAIDs in tap and river water samples.

  10. The Use of Spray-Dried Mn3O4/C Composites as Electrocatalysts for Li–O2 Batteries

    PubMed Central

    Yang, Hong-Kai; Chin, Chih-Chun; Chen, Jenn-Shing

    2016-01-01

    The electrocatalytic activities of Mn3O4/C composites are studied in lithium–oxygen (Li–O2) batteries as cathode catalysts. The Mn3O4/C composites are fabricated using ultrasonic spray pyrolysis (USP) with organic surfactants as the carbon sources. The physical and electrochemical performance of the composites is characterized by X-ray diffraction, scanning electron microscopy, particle size analysis, Brunauer–Emmett–Teller (BET) measurements, elemental analysis, galvanostatic charge–discharge methods and rotating ring-disk electrode (RRDE) measurements. The electrochemical tests demonstrate that the Mn3O4/C composite that is prepared using Trition X-114 (TX114) surfactant has higher activity as a bi-functional catalyst and delivers better oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) catalytic performance in Li–O2 batteries because there is a larger surface area and particles are homogeneous with a meso/macro porous structure. The rate constant (kf) for the production of superoxide radical (O2•−) and the propylene carbonate (PC)-electrolyte decomposition rate constant (k) for M3O4/C and Super P electrodes are measured using RRDE experiments and analysis in the 0.1 M tetrabutylammonium hexafluorophosphate (TBAPF6)/PC electrolyte. The results show that TX114 has higher electrocatalytic activity for the first step of ORR to generate O2•− and produces a faster PC-electrolyte decomposition rate. PMID:28335331

  11. Effect of a room-temperature ionic liquid on the structure and properties of electrospun poly(vinylidene fluoride) nanofibers.

    PubMed

    Xing, Chenyang; Guan, Jipeng; Li, Yongjin; Li, Jingye

    2014-03-26

    Novel anti-static nanofibers based on blends of poly(vinylidene fluoride) (PVDF) and a room-temperature ionic liquid (RTIL), 1-butyl-3-methylimidazolium hexafluorophosphate [BMIM][PF6], were fabricated using an electrospinning approach. The effects of the RTIL on the morphology, crystal structure, and physical properties of the PVDF nanofibers were investigated. Incorporation of RTIL leads to an increase in the mean fiber diameter and the rough fiber surface of the PVDF/RTIL composite nanofibers compared with the neat PVDF nanofibers. The PVDF in the PVDF/RTIL nanofibers exhibits an extremely high content (almost 100%) of β crystals, in contrast to the dominance of PVDF γ crystals in bulk melt-blended PVDF/RTIL blends. Nonwoven fabrics produced from the electrospun PVDF/RTIL composite nanofibers show better stretchability and higher electrical conductivity than those made from neat PVDF without RTIL, and are thus excellent antielectrostatic fibrous materials. In addition, RTIL greatly improved the hydrophobicity of the PVDF fibers, enabling them to effectively separate a mixture of tetrachloromethane (CCl4) and water. The extremely high β content, excellent antielectrostatic properties, better stretchability, and hydrophobicity of the present PVDF/RTIL nanofibers make them a promising candidate for micro- and nanoscale electronic device applications.

  12. Self-assembled thin film of imidazolium ionic liquid on a silicon surface: Low friction and remarkable wear-resistivity

    NASA Astrophysics Data System (ADS)

    Gusain, Rashi; Kokufu, Sho; Bakshi, Paramjeet S.; Utsunomiya, Toru; Ichii, Takashi; Sugimura, Hiroyuki; Khatri, Om P.

    2016-02-01

    Imidazolium-hexafluorophosphate (ImPF6) ionic liquid thin film is prepared on a silicon surface using 3-chloropropyltrimethoxysilane as a bifunctional chemical linker. XPS result revealed the covalent grafting of ImPF6 thin film on a silicon surface. The atomic force microscopic images demonstrated that the ImPF6 thin film is composed of nanoscopic pads/clusters with height of 3-7 nm. Microtribological properties in terms of coefficient of friction and wear-resistivity are probed at the mean Hertzian contact pressure of 0.35-0.6 GPa under the rotational sliding contact. The ImPF6 thin film exhibited low and steady coefficient of friction (μ = 0.11) along with remarkable wear-resistivity to protect the underlying silicon substrate. The low shear strength of ImPF6 thin film, the covalent interaction between ImPF6 ionic liquid thin film and underlying silicon substrate, and its regular grafting collectively reduced the friction and improved the anti-wear property. The covalently grafted ionic liquid thin film further shows immense potential to expand the durability and lifetime of M/NEMS based devices with significant reduction of the friction.

  13. Screening of lignan patterns in Schisandra species using ultrasonic assisted temperature switch ionic liquid microextraction followed by UPLC-MS/MS analysis.

    PubMed

    Dong, Wei; Yu, Shuijing; Deng, Yangwu; Pan, Tao

    2016-01-01

    The ultrasonic assisted temperature-switch ionic liquid microextraction (UATS-ILME) has been successfully applied in extracting of seven lignans from Schisandra. 1-Butyl-3-methylimidazolium tetrafluoroborate ([C4MIM][BF4]) aqueous solution was selected for extracting the target analytes in raw material at 80°C. The lignans were deposited into a single drop by in situ forming 1-butyl-3-methylimidazolium hexafluorophosphate ([C4MIM][PF6]) by cooling down to 0°C and centrifuging for 10min. The extracts were analyzed by ultra-performance liquid chromatography tandem mass spectrometry (UPLC-MS/MS) in a robust multiple-reaction monitoring (MRM) mode in five minutes. Meanwhile, the proposed method was validated and successfully applied to the determination of seven lignans in twelve Schisandra species. The results indicated that UATS-ILME combined with UPLC-MS/MS is a powerful and practical tool, which has great potential for comprehensive quality control of herbal medicines.

  14. Field Effect Transistors Using Atomically Thin Layers of Copper Indium Selenide (CuInSe)

    NASA Astrophysics Data System (ADS)

    Patil, Prasanna; Ghosh, Sujoy; Wasala, Milinda; Lei, Sidong; Vajtai, Robert; Ajayan, Pulickel; Talapatra, Saikat

    We will report fabrication of field-effect transistors (FETs) using few-layers of Copper Indium Selenide (CuInSe) flakes exfoliated from crystals grown using chemical vapor transport technique. Our transport measurements indicate n-type FET with electron mobility µ ~ 3 cm2 V-1 s-1 at room temperature when Silicon dioxide (SiO2) is used as a back gate. Mobility can be further increased significantly when ionic liquid 1-Butyl-3-methylimidazolium hexafluorophosphate (BMIM-PF6) is used as top gate. Similarly subthreshold swing can be further improved from 103 V/dec to 0.55 V/dec by using ionic liquid as a top gate. We also found ON/OFF ratio of ~ 102 for both top and back gate. Comparison between ionic liquid top gate and SiO2 back gate will be presented and discussed. This work is supported by the U.S. Army Research Office through a MURI Grant # W911NF-11-1-0362.

  15. Pyrrolidinium ionic liquid crystals.

    PubMed

    Goossens, Karel; Lava, Kathleen; Nockemann, Peter; Van Hecke, Kristof; Van Meervelt, Luc; Driesen, Kris; Görller-Walrand, Christiane; Binnemans, Koen; Cardinaels, Thomas

    2009-01-01

    N-alkyl-N-methylpyrrolidinium cations have been used for the design of ionic liquid crystals, including a new type of uranium-containing metallomesogen. Pyrrolidinium salts with bromide, bis(trifluoromethylsulfonyl)imide, tetrafluoroborate, hexafluorophosphate, thiocyanate, tetrakis(2- thenoyltrifluoroacetonato)europate(III) and tetrabromouranyl counteranions were prepared. For the bromide salts and tetrabromouranyl compounds, the chain length of the alkyl group C(n)H(2n+1) was varied from eight to twenty carbon atoms (n = 8, 10-20). The compounds show rich mesomorphic behaviour: highly ordered smectic phases (the crystal smectic E phase and the uncommon crystal smectic T phase), smectic A phases, and hexagonal columnar phases were observed, depending on chain length and anion. This work gives better insight into the nature and formation of the crystal smectic T phase, and the molecular requirements for the appearance of this highly ordered phase. This uncommon tetragonal mesophase is thoroughly discussed on the basis of detailed powder X-ray diffraction experiments and in relation to the existing literature. Structural models are proposed for self-assembly of the molecules within the smectic layers. In addition, the photophysical properties of the compounds containing a metal complex anion were investigated. For the uranium-containing mesogens, luminescence can be induced by dissolving them in an ionic liquid matrix. The europium-containing compound shows intense red photoluminescence with high colour purity.

  16. Improved Low-Temperature Performance of Li-Ion Cells Using New Electrolytes

    NASA Technical Reports Server (NTRS)

    Smart, Marshall C.; Buga, Ratnakumar V.; Gozdz, Antoni S.; Mani, Suresh

    2010-01-01

    As part of the continuing efforts to develop advanced electrolytes to improve the performance of lithium-ion cells, especially at low temperatures, a number of electrolyte formulations have been developed that result in improved low-temperature performance (down to 60 C) of 26650 A123Systems commercial lithium-ion cells. The cell type/design, in which the new technology has been demonstrated, has found wide application in the commercial sector (i.e., these cells are currently being used in commercial portable power tools). In addition, the technology is actively being considered for hybrid electric vehicle (HEV) and electric vehicle (EV) applications. In current work, a number of low-temperature electrolytes have been developed based on advances involving lithium hexafluorophosphate-based solutions in carbonate and carbonate + ester solvent blends, which have been further optimized in the context of the technology and targeted applications. The approaches employed, which include the use of ternary mixtures of carbonates, the use of ester co-solvents [e.g., methyl butyrate (MB)], and optimized lithium salt concentrations (e.g., LiPF6), were compared with the commercial baseline electrolyte, as well as an electrolyte being actively considered for DoE HEV applications and previously developed by a commercial enterprise, namely LiPF6 in ethylene carbonate (EC) + ethyl methyl carbonate (EMC)(30:70%).

  17. Ultrasensitive electrochemical biosensor based on reduced graphene oxide-tetraethylene pentamine-BMIMPF6 hybrids for the detection of α2,6-sialylated glycans in human serum.

    PubMed

    Li, Yuliang; He, Junlin; Niu, Yazhen; Yu, Chao

    2015-12-15

    In this paper, a simple, ultrasensitive and label-free electrochemical α2,6-sialylated glycans biosensor based on reduced graphene oxide-tetraethylene pentamine-1-butyl-3-methylimidazolium hexafluorophosphate (BMIMPF6) hybrids was developed. Due to the abundance of amino groups from reduced graphene oxide-tetraethylene pentamine (rGO-TEPA) and the electrostatic interaction of BMIMPF6, bimetallic gold platinum alloy nanoparticles (AuPtNPs) were densely adsorbed onto the surface of the nanocomposite, providing a large surface area available for the immobilization of Sambucus nigra agglutinin (SNA). AuPtNPs have excellent conductivity and catalytic activity, which can promote electron transfer between the electrolyte solution and the surface of electrode and can enhance the sensitivity of biosensor. SNA, which specifically binds α2,6-sialylated glycans, was covalently immobilized on AuPtNPs for specific detection of α2,6-sialylated glycans in human serum. Under optimal experimental conditions, amperometric response changes were used to detect α2,6-sialylated glycans with a broad linear range of 10 fg mL(-1) -1 μg mL(-1) and a low detection limit of 3 fg mL(-1) (S/N=3). When applied to spiked serum samples, the recovery of the developed biosensor ranged from 100.8% to 101.4%, suggesting that the electrochemical biosensor would be suitable for the practical detection of α2,6-sialylated glycans.

  18. Comparative ecotoxicology study of two neoteric solvents: Imidazolium ionic liquid vs. glycerol derivative.

    PubMed

    Perales, Eduardo; García, Cristina Belén; Lomba, Laura; Aldea, Luis; García, José Ignacio; Giner, Beatriz

    2016-10-01

    In this study we have compared the acute ecotoxicity of two solvents, with very different structure and origin, but sharing many physical-chemical properties, so they can be used for similar purposes; a well-known ionic liquid 1-butyl-3-methylimidazolium hexafluorophosphate ([BMIM][PF6]) and a solvent partially derived from biomass, 3-bis(2,2,2-trifluoroethoxy)propan-2-ol (BTFIP). We have used three biomodels (Vibrio fischeri, Daphnia magna and Danio rerio) and performed the comparison applying the Environmental, Health and Safety (EHS) hazard assessment. According to the results, ecotoxicity of [BMIM][PF6] and BTFIP is quite similar in the simplest model Vibrio fischeri, while in Daphnia magna [BMIM][PF6] is clearly more toxic. However, in Danio rerio, toxicity of these chemicals is again quite similar and both can be classified as "nontoxic". The higher index value of [BMIM][PF6] in water mediate effect in the EHS assessment indicates that this ionic liquid is more dangerous than BTFIP, although accumulation and degradation properties have not been taken into account. Further studies will be necessary to ascertain these conclusions.

  19. Ion and gas chromatography mass spectrometry investigations of organophosphates in lithium ion battery electrolytes by electrochemical aging at elevated cathode potentials

    NASA Astrophysics Data System (ADS)

    Weber, Waldemar; Wagner, Ralf; Streipert, Benjamin; Kraft, Vadim; Winter, Martin; Nowak, Sascha

    2016-02-01

    The electrochemical aging of commercial non-aqueous lithium hexafluorophosphate (LiPF6)/organic carbonate solvent based lithium ion battery electrolyte has been investigated in view of the formation of ionic and non-ionic alkylated phosphates. Subject was a solvent mixture of ethylene carbonate/ethyl methyl carbonate EC:EMC (1:1, by wt.) with 1 M LiPF6 (LP50 Selectilyte™, BASF). The analysis was carried out by ion chromatography coupled with electrospray ionization mass spectrometry (ESI-MS) for ionic compounds and (headspace) gas chromatography mass spectrometry ((HS)-GC-MS) for non-ionic compounds. The electrochemical aging was performed by galvanostatic charge/discharge cycling and potentiostatic experiments with LiNi0.5Mn1.5O4 (LMNO) as cathode material at increased cut-off potentials (>4.5 V vs. Li/Li+). A strong dependence of the formation of organophosphates on the applied electrode potential was observed and investigated by quantitative analysis of the formed phosphates. In addition, new possible "fingerprint" compounds for describing the electrolyte status were investigated and compared to existing compounds.

  20. Ionic liquid supported acid/base-catalyzed production of biodiesel.

    PubMed

    Lapis, Alexandre A M; de Oliveira, Luciane F; Neto, Brenno A D; Dupont, Jairton

    2008-01-01

    The transesterification (alcoholysis) reaction was successfully applied to synthesize biodiesel from vegetable oils using imidazolium-based ionic liquids under multiphase acidic and basic conditions. Under basic conditions, the combination of the ionic liquid 1-n-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide (BMINTf2), alcohols, and K2CO3 (40 mol %) results in the production of biodiesel from soybean oil in high yields (>98%) and purity. H2SO4 immobilized in BMINTf2 efficiently promotes the transesterification reaction of soybean oil and various primary and secondary alcohols. In this multiphase process the acid is almost completely retained in the ionic liquid phase, while the biodiesel forms a separate phase. The recovered ionic liquid containing the acid could be reused at least six times without any significant loss in the biodiesel yield or selectivity. In both catalytic processes (acid and base), the reactions proceed as typical multiphasic systems in which the formed biodiesel accumulates as the upper phase and the glycerol by-product is selectively captured by the alcohol-ionic liquid-acid/base phase. Classical ionic liquids such as 1-n-butyl-3-methylimidazolium tetrafluoroborate and hexafluorophosphate are not stable under these acidic or basic conditions and decompose.

  1. Heterogeneity in a room-temperature ionic liquid: persistent local environments and the red-edge effect.

    PubMed

    Hu, Zhonghan; Margulis, Claudio J

    2006-01-24

    In this work, we investigate the slow dynamics of 1-butyl-3-methylimidazolium hexafluorophosphate, a very popular room-temperature ionic solvent. Our study predicts the existence of heterogeneity in the liquid and shows that this heterogeneity is the underlying microscopic cause for the recently reported "red-edge effect" (REE) observed in the study of fluorescence of the organic probe 2-amino-7-nitrofluorene. This theoretical work explains in microscopic terms the relation between REE and dynamic heterogeneity in a room-temperature ionic liquid (IL). The REE is typical of micellar or colloidal systems, which are characterized by microscopic environments that are structurally very different. In contrast, in the case of this room-temperature IL, the REE occurs because of the long period during which molecules are trapped in quasistatic local solvent cages. This trapping time, which is longer than the lifetime of the excited-state probe, together with the inability of the surroundings to adiabatically relax, induces a set of site-specific spectroscopic responses. Subensembles of fluorescent molecules associated with particular local environments absorb and emit at different frequencies. We describe in detail the absorption wavelength-dependent emission spectra of 2-amino-7-nitrofluorene and show that this dependence on lambda(ex) is characteristic of the IL and, as is to be expected, is absent in the case of a normal solvent such as methanol.

  2. Excitation-energy dependence of solvation dynamics in room-temperature ionic liquids

    NASA Astrophysics Data System (ADS)

    Kim, Daekeon; Park, Sang-Won; Shim, Youngseon; Kim, Hyung J.; Jung, YounJoon

    2016-07-01

    Influence of the excitation energy of a probe solute molecule on its solvation dynamics and emission spectrum in 1-ethyl-3-methylimidazolium hexafluorophosphate (EMI+PF6-) is studied via molecular dynamics simulations using a coarse-grained model description. By exciting the probe at different energies, each with an extremely narrow distribution, ensuing solvent relaxation and its dynamic variance are monitored using the isoconfigurational ensemble method. Resulting Stokes shift function, S(t), indicates that long-time solvent relaxation becomes slower with the decreasing excitation energy and approaches the equilibrium correlation function, C(t), of solvent fluctuations. This suggests that the system excited at the red-edge of the spectrum observes linear response better than that at the blue-edge. A detailed analysis of nonequilibrium trajectories shows that the effect of initial configurations on variance of relaxation dynamics is mainly confined to short times; it reaches a maximum around 0.1 ≲ t ≲ 1 ps and diminishes as time further increases. The influence of the initial velocity distribution, on the other hand, tends to grow with time and dominates the long-time variations of dynamics. The emission spectrum shows the red-edge effect in accord with previous studies.

  3. A novel ionic liquid/micro-volume back extraction procedure combined with flame atomic absorption spectrometry for determination of trace nickel in samples of nutritional interest.

    PubMed

    Dadfarnia, Shayesteh; Shabani, Ali Mohammad Haji; Bidabadi, Mahboubeh Shirani; Jafari, Abbas Ali

    2010-01-15

    A simple, highly sensitive and environment-friendly method for the determination of trace amount of nickel ion in different matrices is proposed. In the preconcentration step, the nickel from 10 mL of an aqueous solution was extracted into 500 microL of ionic liquid, 1-butyl-3-methylimidazolium hexafluorophosphate [C(4)MIM][PF(6)], containing PAN as complexing agent. Subsequently, the PAN complex was back-extracted into 250 microL of nitric acid solution, and 100 microL of it was analyzed by flow injection flame atomic absorption spectrometry (FI-FAAS). The main parameter influencing the extraction and determination of nickel, such as pH, concentration of PAN, extraction time and temperature, ionic strength, and concentration of stripping acid solution, were optimized. An enhancement factor of 40.2 was achieved with 25 mL sample. The limit of detection (LOD) and quantification obtained under the optimum conditions were 12.5 and 41.0 microg L(-1), respectively. To validate the proposed methods two certified reference materials 681-I and BCR No. 288 were analyzed and the results were in good agreement with the certified values. The proposed method was successfully applied to determination of nickel in water samples, rice flour and black tea.

  4. Syntheses and crystal structures of benzene-sulfonate and -carboxylate copper polymers and their application in the oxidation of cyclohexane in ionic liquid under mild conditions.

    PubMed

    Hazra, Susanta; Ribeiro, Ana P C; Guedes da Silva, M Fátima C; Nieto de Castro, Carlos A; Pombeiro, Armando J L

    2016-09-21

    The syntheses, crystal structures and catalytic activities of the polymers derived from 2-(2-pyridylmethyleneamino)benzenesulfonic acid (HL), viz. [CuL(H2tma)]n (1) and [{Cu2L2(H2pma)}·(8H2O)]n (2) [H3tma = benzene-1,3,5-tricarboxylic (trimesic) acid and H4pma = benzene-1,2,4,5-tetracarboxylic (pyromellitic) acid], are presented. Despite the comparable combinations and compositions of ligands (sulfonate and carboxylate) in these two polymers the bridging moiety in 1 is sulfonate while in 2 it is carboxylate. Complexes 1 and 2 act as catalysts in the peroxidative oxidation of cyclohexane under mild conditions using either the ionic liquid 1-butyl-3-methylimidazolium hexafluorophosphate [bmim][PF6] or acetonitrile as the solvent. The ionic liquid medium leads to increases in the yields and in the turnover numbers, achieved in shorter reaction times in comparison with those when using the conventional acetonitrile solvent. A simple recycling of the catalysts in the ionic liquid medium is achieved without loss of activity and selectivity.

  5. Nonaqueous electrolyte for electrical storage devices

    DOEpatents

    McEwen, Alan B.; Yair, Ein-Eli

    1999-01-01

    Improved nonaqueous electrolytes for application in electrical storage devices such as electrochemical capacitors or batteries are disclosed. The electrolytes of the invention contain salts consisting of alkyl substituted, cyclic delocalized aromatic cations, and their perfluoro derivatives, and certain polyatomic anions having a van der Waals volume less than or equal to 100 .ANG..sup.3, preferably inorganic perfluoride anions and most preferably PF.sub.6.sup.-, the salts being dissolved in organic liquids, and preferably alkyl carbonate solvents, or liquid sulfur dioxide or combinations thereof, at a concentration of greater than 0.5M and preferably greater than 1.0M. Exemplary electrolytes comprise 1-ethyl-3-methylimidazolium hexafluorophosphate dissolved in a cyclic or acylic alkyl carbonate, or methyl formate, or a combination therof. These improved electrolytes have useful characteristics such as higher conductivity, higher concentration, higher energy storage capabilities, and higher power characteristics compared to prior art electrolytes. Stacked capacitor cells using electrolytes of the invention permit high energy, high voltage storage.

  6. Ligandless ultrasonic-assisted and ionic liquid-based dispersive liquid-liquid microextraction of copper, nickel and lead in different food samples.

    PubMed

    Jalbani, N; Soylak, M

    2015-01-15

    A simple and rapid ultrasonic assisted-ionic liquid based-liquid-liquid microextraction (UA-IL-DLLME) method has been developed for the enrichment and separation of Cu(II), Ni(II) and Pb(II). A two level factorial design was used to determine the effect of key factors such as pH, volume of ionic liquid (IL), carbon tetra chloride (CCl4) and sonication time (St). 1-Butyl-3-methylimidazolium hexafluorophosphate ([C4MIM][PF6]) and CCl4 were used as an extractant and dispersant solvent, respectively. The accuracy of the proposed method was evaluated by analysing of SRM Apple Leaves 1515 certified reference material. The limits of detections (LODs) were 0.17 μg/L, 0.49 μg/L and 0.95 μg/L for Cu, Ni and Pb, respectively. The enrichment factor (EF) was 100. The method has been successfully applied for the analysis of the content of Cu, Ni and Pb in spice, vegetable and fruit samples by flame atomic absorption spectrometry (FAAS).

  7. Self-Assembled Functional Nanostructure of Plasmid DNA with Ionic Liquid [Bmim][PF₆]: Enhanced Efficiency in Bacterial Gene Transformation.

    PubMed

    Soni, Sarvesh K; Sarkar, Sampa; Mirzadeh, Nedaossadat; Selvakannan, P R; Bhargava, Suresh K

    2015-04-28

    The electrostatic interaction between the negatively charged phosphate groups of plasmid DNA and the cationic part of hydrophobic ionic liquid 1-butyl-3-methylimidazolium hexafluorophosphate ([Bmim][PF6]), initiates spontaneous self-assembly to form the functional nanostructures made up of DNA and ionic liquid (IL). These functional nanostructures were demonstrated as promising synthetic nonviral vectors for the efficient bacterial pGFP gene transformation in cells. In particular, the functional nanostructures that were made up of 1 μL of IL ([Bmim][PF6]) and 1 μg of plasmid DNA can increase the transformation efficiency by 300-400% in microbial systems, without showing any toxicity for E. coli DH5α cells. (31)P nuclear magnetic resonance (NMR), Fourier transform infrared (FTIR) spectroscopy, and X-ray photoelectron (XPS) spectroscopic analysis revealed that the electrostatic interaction between negatively charged phosphate oxygen and cationic Bmim(+) tends to initiate the self-assembly process. Thermogravimetric analysis of the DNA-IL functional nanostructures showed that these nanostructures consist of ∼16 wt % ionic liquid, which is considered to provide the stability to the plasmid DNA that eventually enhanced the transformation efficiency.

  8. Preparation and characterization of new low melting ammonium-based ionic liquids with ether functionality

    NASA Astrophysics Data System (ADS)

    Kärnä, Minna; Lahtinen, Manu; Valkonen, Jussi

    2009-03-01

    Eighteen new and three previously known but insufficiently characterized RŔ 3N +A - and R 2Ŕ 2N +A - type ( R = 2-ethoxyethyl or 4-methoxybenzyl, Ŕ = methyl, ethyl, n-propyl, n-butyl, n-pentyl or n-hexyl, A = Br, BF 4 or PF 6) quaternary ammonium (QA) salts were synthesized and characterized by using 1H and 13C NMR techniques, mass spectroscopy and elemental analysis. The bromide salts were synthesized either by treating dimethyl formamide with an ether functionalized alkyl bromide in the presence of potassium carbonate or by treating a tertiary amine with an ether functionalized alkyl bromide. The QA tetrafluoroborates and hexafluorophosphates were synthesized by metathesis reaction between a prepared QA bromide and HBF 4 or KPF 6. The crystal structures of four compounds were determined by X-ray single crystal diffraction and powder diffraction was used to study the crystallinity of the solid compounds and to compare the structural similarities between the single crystals and the microcrystalline bulk form. Thermal properties of all compounds were studied by using TG/DTA and DSC methods. The anion exchange had a clear lowering effect on the melting points and enhanced the thermal stability of the BF4- and PF6- salts compared to the analogous bromides. Most of the compounds melted clearly below 100 °C, of which four are liquid at room temperature.

  9. Influence of the counteranion on the ability of 1-dodecyl-3-methyltriazolium ionic liquids to form mesophases

    SciTech Connect

    Stappert, Kathrin; Unal, Derya; Spielberg, Eike T.; Mudring, Anja -Verena

    2014-11-25

    The influence of the counteranion on the ability of the mesogenic cation 1-methyl-3-dodecyl-triazolium to form mesophases is explored. To that avail, salts of the cation with anions of different size, shape, and hydrogen bonding capability such as Cl, Br, I, I3, PF6, and Tf2N [bis(trifluorosulfonyl)amide] were synthesized and characterized. The crystal structures of the bromide, the iodide, and the triiodide reveal that the cations form bilayers with cations oriented in opposite directions featuring interdigitated alkyl tails. Within the layers, the cations are separated by anions. The rod-shaped triiodide anion forces the triazolium cation to align with it in this crystal structure but due to its space requirement reduces the alkyl chain interdigitation which prevents the formation of a mesophase. Rather the compound transforms directly from a crystalline solid to an (ionic) liquid like the analogous bis(trifluorosulfonyl)amide. In contrast, the simple halides and the hexafluorophosphate form liquid crystalline phases. As a result, their clearing points shift with increasing anion radius to lower temperatures.

  10. Tyrosine-Based Ionic Liquid Crystals: Switching from a Smectic A to a Columnar Mesophase by Exchange of the Spherical Counterion.

    PubMed

    Neidhardt, Manuel M; Wolfrum, Manpreet; Beardsworth, Stuart; Wöhrle, Tobias; Frey, Wolfgang; Baro, Angelika; Stubenrauch, Cosima; Giesselmann, Frank; Laschat, Sabine

    2016-11-07

    Synthetic strategies were developed to prepare l-tyrosine-based ionic liquid crystals with structural variations at the carboxylic and phenolic OH groups as well as the amino functionality. Salt metathesis additionally led to counterion variation. The liquid-crystalline properties were investigated by differential scanning calorimetry (DSC), polarizing optical microscopy (POM) and X-ray diffraction (WAXS, SAXS). The symmetrical ILC chlorides bearing the same alkyl chain at both the ester and ether but either an acyclic or cyclic guanidinium group displayed enantiotropic SmA2 mesophases with phase widths of 31-88 K irrespective of the head group. It was particularly the replacement of chloride in the acyclic guanidinium ILC by hexafluorophosphate that induced a phase change from SmA2 to Colr . This phase change was attributed to a higher curvature of the interface due to the larger anion, which increased the effective head group cross-sectional area of the amphiphilic ILC. The unsymmetrical acyclic guanidinium chlorides, bearing a constant C14 ester and variable alkyl chains on the phenolic position, formed enantiotropic SmA2 phases. The derivative with the largest difference in chain lengths, however, displayed a Colr phase, resulting from discoid aggregates of the cone-shaped guanidinium chloride. The results are discussed in terms of the packing parameters, which indicate that the phase behaviour of the thermotropic tyrosine-based ILCs shows analogies to those of lyotropic liquid crystals.

  11. A kinetic study of ferrocenium cation decomposition utilizing an integrated electrochemical methodology composed of cyclic voltammetry and amperometry.

    PubMed

    Singh, Archana; Chowdhury, Debarati Roy; Paul, Amit

    2014-11-21

    A novel, easy, quick, and inexpensive integrated electrochemical methodology composed of cyclic voltammetry and amperometry has been developed for the determination of the kinetic stability of higher oxidation states for inorganic complexes. In this study, ferrocene and its derivatives have been used as model systems and the corresponding ferrocenium cations were generated in situ during the electrochemical experiments to determine their kinetic stabilities. The study found that the ferrocenium cations decompose following the first-order kinetics at 27 ± 3 °C in the presence of ambient oxygen and water. The half-lives of the ferrocenium, carboxylate ferrocenium, and decamethyl ferrocenium cations were found to be 1.27 × 10(3), 1.52 × 10(3), and ≫11.0 × 10(3) s, respectively, in acetonitrile solvent having a 0.5 M tetrabutylammonium hexafluorophosphate electrolyte. These results are in agreement with the previous reports, i.e. the ferrocenium cation is unstable whereas the decamethyl ferrocenium cation has superior stability. The new methodology has been established by performing various experiments using different concentrations of ferrocene, variable scan rates in cyclic voltammetry, different time periods for amperometry, and in situ spectroelectrochemical experiments.

  12. Activated carbon and single-walled carbon nanotube based electrochemical capacitor in 1 M LiPF{sub 6} electrolyte

    SciTech Connect

    Azam, M.A.; Jantan, N.H.; Dorah, N.; Seman, R.N.A.R.; Manaf, N.S.A.; Kudin, T.I.T.; Yahya, M.Z.A.

    2015-09-15

    Highlights: • Activated carbon and single-walled CNT based electrochemical capacitor. • Electrochemical analysis by means of CV, charge/discharge and impedance. • 1 M LiPF{sub 6} non-aqueous solution as an electrolyte. • AC/SWCNT electrode exhibits a maximum capacitance of 60.97 F g{sup −1}. - Abstract: Carbon nanotubes have been extensively studied because of their wide range of potential application such as in nanoscale electric circuits, textiles, transportation, health, and the environment. Carbon nanotubes feature extraordinary properties, such as electrical conductivities higher than those of copper, hardness and thermal conductivity higher than those of diamond, and strength surpassing that of steel, among others. This research focuses on the fabrication of an energy storage device, namely, an electrochemical capacitor, by using carbon materials, i.e., activated carbon and single-walled carbon nanotubes, of a specific weight ratio as electrode materials. The electrolyte functioning as an ion carrier is 1 M lithium hexafluorophosphate. Variations in the electrochemical performance of the device, including its capacitance, charge/discharge characteristics, and impedance, are reported in this paper. The electrode proposed in this work exhibits a maximum capacitance of 60.97 F g{sup −1} at a scan rate of 1 mV s{sup −1}.

  13. Preconcentration and determination of lead and cadmium levels in blood samples of adolescent workers consuming smokeless tobacco products in Pakistan.

    PubMed

    Arain, Sadaf Sadia; Kazi, Tasneem Gul; Afridi, Hassan Imran; Brahman, Kapil Dev; Naeemullah; Khan, Sumaira; Panhwar, Abdul Haleem; Kamboh, Muhammad Afzal; Memon, Jamil R

    2015-05-01

    The present study was aimed to evaluate the cadmium (Cd) and lead (Pb) levels in the blood samples of adolescent boys, chewing different smokeless tobacco (SLT) products in Pakistan. For comparative purpose, boys of the same age group (12-15 years), not consumed any SLT products were selected as referents. To determine trace levels of Cd and Pb in blood samples, a preconcentration method, vortex-assisted liquid-liquid microextraction (VLLME) has been developed, prior to analysis by flame atomic absorption spectrometry. The hydrophobic chelates of Cd and Pb with ammonium pyrrolidinedithiocarbamate were extracted into the fine droplets of ionic liquid (IL) 1-butyl-3-methylimidazolium hexafluorophosphate, while nonionic surfactant, Triton X-114 was used as a dispersing medium. The main factors affecting the recoveries of Cd and Pb, such as concentration of APDC, centrifugation time, volume of IL and TX-114, were investigated in detail. It was also observed that adolescent boys who consumed different SLT products have 2- to 3-fold higher levels of Cd and Pb in their blood samples as compared to referent boys (p < 0.001).

  14. Laser desorption from a room temperature ionic liquid

    NASA Astrophysics Data System (ADS)

    Harris, Peter Ronald

    We report laser desorption from a Room Temperature Ionic Liquid (RTIL) as a novel source for time of flight mass spectrometry. We use the 2nd harmonic of an Nd:YAG laser to deposit intensities of 1-50 MW/cm2 via backside illumination onto our RTIL desorption sample. A microstructured metal grid situated on top of a glass microscope slide coated with RTIL serves as our desorption sample. The RTIL we use, 1-Butyl, 3-Methylimidazolium Hexafluorophosphate, remains liquid at pressures below 10-8 torr. The use of liquid desorption sample allows for improved surface conditions, homogeneity and sample life as compared to Matrix Assisted Laser Desorption Ionization (MALDI) techniques. Our desorption technique is also unique as it allows the study of both multiphoton and acoustic desorption processes within the same time of flight spectra. Our technique yields intrinsically high resolution, low noise data. We observe differences between ion species in their preference for desorption by a particular desorption method. Specifically, we observe desorption solely by acoustic means of an entire RTIL molecule adducted with an RTIL cation. Finally, we report the applicability of this technique for the desorption of biomolecules.

  15. Development of biosensor for phenolic compounds containing PPO in β-cyclodextrin modified support and iridium nanoparticles.

    PubMed

    da Silva, Cristiano P; Franzoi, Ana C; Fernandes, Suellen C; Dupont, Jairton; Vieira, Iolanda C

    2013-04-10

    A biosensor based on the iridium nanoparticles dispersed in ionic liquid (IL) 1-butyl-3-methylimidazolium hexafluorophosphate (Ir-BMI·PF6) and a celery (Apium graveolens) extract as a source of polyphenol oxidase (PPO) was constructed. A modified support based on β-cyclodextrin (β-CDEP) was used for enzyme immobilization. The behavior of phenolic compounds was investigated by square-wave voltammetry and rutin was selected by presenting the greatest signal. The best performance was obtained with a composition of 70:10:10:10% (w/w/w/w) of the graphite powder:β-CDEP:Nujol:Ir-BMI·PF6 composition, a PPO concentration of 500unitsmL(-1), in 0.1M phosphate buffer solution (pH 6.0) with frequency, pulse amplitude and scan increment at 100Hz, 60mV, and 3.0mV, respectively. Under optimized conditions, the cathodic currents increased linearly for the rutin concentration range of 1.3×10(-7)-2.0×10(-6)M with a detection limit of 7.9×10(-8)M. This sensor demonstrated acceptable repeatability and reproducibility and the results for the rutin recovery ranged from 92.8 to 103.4%. A relative error of 0.7% was obtained in the rutin determination in simulated samples.

  16. Ionic liquid-based vortex-assisted dispersive liquid-liquid microextraction of organophosphorus pesticides in apple and pear.

    PubMed

    Zhang, Lijin; Chen, Fang; Liu, Shaowen; Chen, Biyu; Pan, Canping

    2012-09-01

    An ionic liquid-based vortex-assisted dispersive liquid-liquid microextraction (DLLME) was developed for the analysis of trace amounts of six organophosphorus pesticides (OPPs) in apple and pear coupled with high-performance liquid chromatography. During the DLLME, the effect of some experimental factors including extraction solvent and its volume, dispersion solvent and its volume, vortex time, salt addition, and pH on the extraction procedure were investigated. Under the chosen extraction conditions, the analytes were enriched more than 300-fold and the limits of detections were greatly dropped to 0.061-0.73 μg/kg. The linearity relationship was observed in the range of 2-100 μg/kg with the correlation coefficients (R(2)) ranging from 0.9967 to 0.9983. The relative standard deviations varied from 2.3 to 5.7% (n = 6). Mean recovery values of the OPPs were in the range of 69.8-109.1% with a relative standard deviation lower than 7.0%. Based on these above, it could be concluded that 1-octyl-3-methylimidazolium hexafluorophosphate ([C(8)MIM][PF(6)]) was a good extraction solvent and the proposed [C(8)MIM][PF(6)]-based vortex-assisted DLLME method was suitable for the effective extraction of the OPPs in apple and pear.

  17. Vortex-assisted ionic liquid microextraction coupled to flame atomic absorption spectrometry for determination of trace levels of cadmium in real samples

    PubMed Central

    Chamsaz, Mahmoud; Atarodi, Atefe; Eftekhari, Mohammad; Asadpour, Saeid; Adibi, Mina

    2012-01-01

    A simple and rapid vortex assisted ionic liquid based liquid–liquid microextraction technique (VALLME) was proposed for preconcentration of trace levels of cadmium. According to this method, the extraction solvent was dispersed into the aqueous samples by the assistance of vortex agitator. Cadmium preconcentration was mediated by chelation with the 8-hydroxyquinoline (oxine) reagent and an IL, 1-octyl-3-methylimidazolium hexafluorophosphate ([Omim][PF6]) was chosen as the extraction solvent to extract the hydrophobic complex. Several variables such as sample pH, concentration of oxine, volume of [Omim][PF6] and extraction time were investigated in details and optimum conditions were selected. Under the optimum conditions, the limit of detection (LOD) was 2.9 μg L−1 for Cd (ІІ) and relative standard deviation (RSD%) for five replicate determinations of 125 μg L−1 was 4.1%. The method was successfully applied to the determination of cadmium in tap water, apple and rice samples. PMID:25685399

  18. Vortex-assisted ionic liquid microextraction coupled to flame atomic absorption spectrometry for determination of trace levels of cadmium in real samples.

    PubMed

    Chamsaz, Mahmoud; Atarodi, Atefe; Eftekhari, Mohammad; Asadpour, Saeid; Adibi, Mina

    2013-01-01

    A simple and rapid vortex assisted ionic liquid based liquid-liquid microextraction technique (VALLME) was proposed for preconcentration of trace levels of cadmium. According to this method, the extraction solvent was dispersed into the aqueous samples by the assistance of vortex agitator. Cadmium preconcentration was mediated by chelation with the 8-hydroxyquinoline (oxine) reagent and an IL, 1-octyl-3-methylimidazolium hexafluorophosphate ([Omim][PF6]) was chosen as the extraction solvent to extract the hydrophobic complex. Several variables such as sample pH, concentration of oxine, volume of [Omim][PF6] and extraction time were investigated in details and optimum conditions were selected. Under the optimum conditions, the limit of detection (LOD) was 2.9 μg L(-1) for Cd (ІІ) and relative standard deviation (RSD%) for five replicate determinations of 125 μg L(-1) was 4.1%. The method was successfully applied to the determination of cadmium in tap water, apple and rice samples.

  19. Separation and pre-concentration of glucocorticoids in water samples by ionic liquid supported vortex-assisted synergic microextraction and HPLC determination.

    PubMed

    Qin, Hui; Li, Bi; Liu, Mou Sheng; Yang, Ya Ling

    2013-04-01

    We have developed a synergic microextraction procedure based on ionic liquid for the pre-concentration and determination of glucocorticoids in water samples. Using nonionic surfactant Triton X-100 (TX-100) as synergic reagent, 1-butyl-3-methylimidazolium hexa-fluorophosphate accomplished extraction rapidly without heating in water bath. One key property of ionic liquids that highlights their potential is their wide liquid temperature range. The improved extraction was named as ionic liquid supported vortex-assisted synergic microextraction. Compared with the traditional liquid-liquid extraction and cloud point extraction, ionic liquid supported vortex-assisted synergic microextraction was accomplished in 8 min with considerably high recovery. The proposed method greatly improved the sensitivity of HPLC for the determination of glucocorticoids. The results obtained indicated a good linearity with the correlation coefficient of 0.997 over the range of 0.6-300 ng/mL and high sensitivity with LODs of 4.11, 9.19, and 7.50 ng/mL for hydrocortisone butyrate, beclomethasone dipropionate, and nandrolone phenylpropionate, respectively. The RSD of the method was 1.57-1.81% (n = 6) with enrichment factor of 99.85, and good recovery (≥97.24%). The method was successfully applied to the determination of glucocorticoids in mineral water, water of Dianchi lake, and tap water samples.

  20. Temperature-controlled ionic liquid-based ultrasound-assisted microextraction for preconcentration of trace quantity of cadmium and nickel by using organic ligand in artificial saliva extract of smokeless tobacco products

    NASA Astrophysics Data System (ADS)

    Arain, Sadaf Sadia; Kazi, Tasneem Gul; Arain, Asma Jabeen; Afridi, Hassan Imran; Baig, Jameel Ahmed; Brahman, Kapil Dev; Naeemullah; Arain, Salma Aslam

    2015-03-01

    A new approach was developed for the preconcentration of cadmium (Cd) and nickel (Ni) in artificial saliva extract of dry snuff (brown and black) products using temperature-controlled ionic liquid-based ultrasound-assisted dispersive liquid-liquid microextraction (TIL-UDLLμE) followed by electrothermal atomic absorption spectrometry (ETAAS). The Cd and Ni were complexed with ammonium pyrrolidinedithiocarbamate (APDC), extracted in ionic liquid drops, 1-butyl-3-methylimidazolium hexafluorophosphate [C4MIM][PF6]. The multivariate strategy was applied to estimate the optimum values of experimental variables influence the % recovery of analytes by TIL-UDLLμE method. At optimum experimental conditions, the limit of detection (3s) were 0.05 and 0.14 μg L-1 while relative standard deviations (% RSD) were 3.97 and 3.55 for Cd and Ni respectively. After extraction, the enhancement factors (EF) were 87 and 79 for Cd and Ni, respectively. The RSD for six replicates of 10 μg L-1 Cd and Ni were 3.97% and 3.55% respectively. To validate the proposed method, certified reference material (CRM) of Virginia tobacco leaves was analyzed, and the determined values of Cd and Ni were in good agreement with the certified values. The concentration of Cd and Ni in artificial saliva extracts corresponds to 39-52% and 21-32%, respectively, of the total contents of both elements in dry brown and black snuff products.

  1. Easy parallel screening of reagent stability, quality control, and metrology in solid phase peptide synthesis (SPPS) and peptide couplings for microarrays.

    PubMed

    Achyuthan, Komandoor E; Wheeler, David R

    2015-10-01

    Evaluating the stability of coupling reagents, quality control (QC), and surface functionalization metrology are all critical to the production of high quality peptide microarrays. We describe a broadly applicable screening technique for evaluating the fidelity of solid phase peptide synthesis (SPPS), the stability of activation/coupling reagents, and a microarray surface metrology tool. This technique was used to assess the stability of the activation reagent 1-{[1-(Cyano-2-ethoxy-2-oxo-ethylidenaminooxy)dimethylamino-morpholinomethylene]}methaneaminiumHexafluorophosphate (COMU) (Sigma-Aldrich, St. Louis, MO, USA) by SPPS of Leu-Enkephalin (YGGFL) or the coupling of commercially synthesized YGGFL peptides to (3-aminopropyl)triethyoxysilane-modified glass surfaces. Coupling efficiency was quantitated by fluorescence signaling based on immunoreactivity of the YGGFL motif. It was concluded that COMU solutions should be prepared fresh and used within 5 h when stored at ~23 °C and not beyond 24 h if stored refrigerated, both in closed containers. Caveats to gauging COMU stability by absorption spectroscopy are discussed. Commercial YGGFL peptides needed independent QC, due to immunoreactivity variations for the same sequence synthesized by different vendors. This technique is useful in evaluating the stability of other activation/coupling reagents besides COMU and as a metrology tool for SPPS and peptide microarrays.

  2. The fluorescence of a chelating two-photon-absorbing dye is enhanced with the addition of transition metal ions but quenched in the presence of acid

    NASA Astrophysics Data System (ADS)

    Stewart, David J.; Long, Stephanie L.; Yu, Zhenning; Kannan, Ramamurthi; Mikhailov, Alexandr; Rebane, Aleksander; Tan, Loon-Seng; Haley, Joy E.

    2016-09-01

    A pseudo-symmetric two-photon absorbing dye (1) containing a central piperazine unit substituted with (benzothiazol-2- yl)-9,9-diethylfluoren-2-yl pendant groups has been synthesized and characterized. The molecule has a two-photonabsorption cross-section of σ2 = 140 GM in tetrahydrofuran at 740 nm and shows significant solvatochromism in the excited-state fluorescence spectra. The emission spectra broaden and the maxima bathochromically shift from 411 nm to 524 nm in n-hexane and acetonitrile, respectively. Moreover, the central piperazine moiety serves as a potential chelation site for ions. Addition of copper(I) hexafluorophosphate and zinc(II) triflate in acetonitrile indicate ground-state complexation with a shift in the emission maximum from 524 nm to 489 nm and 487 nm, respectively. Interestingly, the newly formed Cu and Zn complexes are more strongly emissive than the free dye. Finally, addition of p-toluenesulfonic acid in tetrahydrofuran also blue-shifts the emission maximum, but the intensity is quenched. Due to the photophysical changes induced by addition of metal ions and protons, the dye shows promise as a potential sensor.

  3. Application of graphene-copper sulfide nanocomposite modified electrode for electrochemistry and electrocatalysis of hemoglobin.

    PubMed

    Shi, Fan; Zheng, Weizhe; Wang, Wencheng; Hou, Fei; Lei, Bingxin; Sun, Zhenfan; Sun, Wei

    2015-02-15

    In this paper a graphene (GR) and copper sulfide (CuS) nanocomposite was synthesized by hydrothermal method and used for the electrode modification with a N-butylpyridinium hexafluorophosphate based carbon ionic liquid electrode (CILE) as the substrate electrode. Hemoglobin (Hb) was immobilized on the modified electrode to get a biocompatible sensing platform. UV-vis absorption spectroscopic results confirmed that Hb retained its native secondary structure in the composite. Direct electron transfer of Hb incorporated into the nanocomposite was investigated with a pair of well-defined redox waves appeared on cyclic voltammogram, indicating the realization of direct electrochemistry of Hb on the modified electrode. The results can be ascribed to the presence of GR-CuS nanocomposite on the electrode surface that facilitates the electron transfer rate between the electroactive center of Hb and the electrode. The Hb modified electrode showed excellent electrocatalytic activity to the reduction of trichloroacetic acid in the concentration range from 3.0 to 64.0 mmol L(-1) with the detection limit of 0.20 mmol L(-1) (3σ). The fabricated biosensor displayed the advantages such as high sensitivity, good reproducibility and long-term stability.

  4. Development of a novel gene silencer pyrrole-imidazole polyamide targeting human connective tissue growth factor.

    PubMed

    Wan, Jian-Xin; Fukuda, Noboru; Ueno, Takahiro; Watanabe, Takayoshi; Matsuda, Hiroyuki; Saito, Kosuke; Nagase, Hiroki; Matsumoto, Yoshiaki; Matsumoto, Koichi

    2011-01-01

    Pyrrole-imidazole (PI) polyamide can bind to specific sequences in the minor groove of double-helical DNA and inhibit transcription of the genes. We designed and synthesized a PI polyamide to target the human connective tissue growth factor (hCTGF) promoter region adjacent to the Smads binding site. Among coupling activators that yield PI polyamides, 1-[bis(dimethylamino)methylene]-5-chloro-1H-benzotriazolium 3-oxide hexafluorophosphate (HCTU) was most effective in total yields of PI polyamides. A gel shift assay showed that a PI polyamide designed specifically for hCTGF (PI polyamide to hCTGF) bound the appropriate double-stranded oligonucleotide. A fluorescein isothiocyanate (FITC)-conjugated PI polyamide to CTGF permeated cell membranes and accumulated in the nuclei of cultured human mesangial cells (HMCs) and remained there for 48 h. The PI polyamide to hCTGF significantly decreased phorbol 12-myristate acetate (PMA)- or transforming growth factor-β1 (TGF-β1)-stimulated luciferase activity of the hCTGF promoter in cultured HMCs. The PI polyamide to hCTGF significantly decreased PMA- or TGF-β1-stimulated expression of hCTGF mRNA in a dose-dependent manner. The PI polyamide to hCTGF significantly decreased PMA- or TGF-β1-stimulated levels of hCTGF protein in HMCs. These results indicate that the developed synthetic PI polyamide to hCTGF could be a novel gene silencer for fibrotic diseases.

  5. Synthesis and biological activity of novel amino acid-(N'-benzoyl) hydrazide and amino acid-(N'-nicotinoyl) hydrazide derivatives.

    PubMed

    Khattab, Sherine N

    2005-09-30

    The coupling reaction of benzoic acid and nicotinic acid hydrazides with N- protected L-amino acids including valine, leucine, phenylalanine, glutamic acid and tyrosine is reported. The target compounds, N-Boc-amino acid-(N;-benzoyl)- and N- Boc-amino acid-(N;-nicotinoyl) hydrazides 5a-5e and 6a-6e were prepared in very high yields and purity using N-[(dimethylamino)-1H-1,2,3-triazolo[4,5-b]pyridin-1-yl- methylene]-N-methyl-methanaminium hexafluorophosphate N-oxide (HATU) as coupling reagent. The antimicrobial activity of the Cu and Cd complexes of the designed compounds was tested. The products were deprotected affording the corresponding amino acid-(N;-benzoyl) hydrazide hydrochloride salts (7a-7e) and amino acid-(N;- nicotinoyl) hydrazide hydrochloride salts (8a-8e). These compounds and their Cu and Cd complexes were also tested for their antimicrobial activity. Several compounds showed comparable activity to that of ampicillin against S. aureus and E. coli.

  6. (R)-PAC biosynthesis in [BMIM][PF₆]/aqueous biphasic system using Saccharomyces cerevisiae BY4741 cells.

    PubMed

    Kandar, Smita; Suresh, A K; Noronha, Santosh B

    2015-02-01

    (R)-phenylacetylcarbinol or (R)-PAC is a pharmaceutical precursor of (1R, 2S) ephedrine and (1S, 2S) pseudoephedrine. Biotransformation of benzaldehyde and glucose by pyruvate decarboxylase produces (R)-PAC. This biotransformation suffers from toxicity of the substrate, product [(R)-PAC] and by-product (benzyl alcohol). In the present study, ionic liquid/aqueous biphasic system was employed to enhance (R)-PAC production. Fermented broth was the reaction medium in which Saccharomyces cerevisiae BY4741 was the source of pyruvate decarboxylase. Hydrophobic ionic liquid 1-butyl-3-methylimidazolium hexafluorophosphate ([BMIM][PF6]) was the non-aqueous phase in which toxic compounds reside. Biocompatibility of [BMIM][PF6] and adequate distribution coefficients of benzaldehyde, (R)-PAC and benzyl alcohol were determined. A Box-Behnken design and response surface methodology were used for the optimization of biotransformation variables in order to maximize (R)-PAC yield and productivity. The results showed higher (R)-PAC yield and productivity of ∼1.5-fold each in the biphasic biotransformation of phase volume ratio 0.05 as compared to the monophasic (conventional) biotransformation. Moreover, the level of major by-product benzyl alcohol was also 3.5-fold lower in biphasic biotransformation. [BMIM][PF6]/aqueous biphasic system is a new approach which could intensify the (R)-PAC production.

  7. A novel impedimetric nanobiosensor for low level determination of hydrogen peroxide based on biocatalysis of catalase.

    PubMed

    Shamsipur, Mojtaba; Asgari, Mehdi; Maragheh, Mohammad Ghannadi; Moosavi-Movahedi, Ali Akbar

    2012-02-01

    A robust and effective nanocomposite film-glassy carbon modified electrode based on multi-walled carbon nanotubes and a room temperature ionic liquid 1-butyl-3-methylimidazolium hexafluorophosphate was prepared by a layer-by-layer self-assembly method. The fabricated modified electrode was used as a novel impedimetric catalase nanobiosensor for the determination of H(2)O(2). Direct electron transfer and electrocatalysis of catalase were fully investigated. The results suggested that catalase could be firmly adsorbed at the modified electrode. A pair of quasi-reversible redox peaks of catalase was observed in a 0.20 M degassed phosphate buffer solution of pH 7.0. The nanocomposite film showed a pronounced increase in direct electron transfer between catalase and the electrode. The immobilized catalase exhibited an excellent electrocatalytic activity towards the reduction of H(2)O(2). The electrochemical impedance spectroscopy measurements revealed that the charge transfer resistance decreases significantly after enzymatic reaction with hydrogen peroxide, so that the prepared modified electrode can be used for the detection of ultra traces of H(2)O(2) (5-1700 nM).

  8. Binding energies of CO2 with some ionic liquids

    NASA Astrophysics Data System (ADS)

    Eucker, William; Bendler, John

    2007-03-01

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

  9. Determination of atenolol in human plasma using ionic-liquid-based ultrasound-assisted in situ solvent formation microextraction followed by high-performance liquid chromatography.

    PubMed

    Zeeb, Mohsen; Farahani, Hadi; Papan, Mohammad Kazem

    2016-06-01

    An efficient analytical method called ionic-liquid-based ultrasound-assisted in situ solvent formation microextraction followed by high-performance liquid chromatography was developed for the determination of atenolol in human plasma. A hydrophobic ionic liquid (1-butyl-3-methylimidazolium hexafluorophosphate) was formed by the addition of a hydrophilic ionic liquid (1-butyl-3-methylimidazolium tetrafluoroborate) to a sample solution containing an ion-pairing agent during microextraction. The analyte was extracted into the ionic liquid phase while the microextraction solvent was dispersed throughout the sample by utilizing ultrasound. The sample was then centrifuged, and the extracting phase retracted into the microsyringe and injected to liquid chromatography. After optimization, the calibration curve showed linearity in the range of 2-750 ng/mL with the regression coefficient corresponding to 0.998. The limits of detection (S/N = 3) and quantification (S/N = 10) were 0.5 and 2 ng/mL, respectively. A reasonable relative recovery range of 90-96.7% and satisfactory intra-assay (4.8-5.1%, n = 6) and interassay (5.0-5.6%, n = 9) precision along with a substantial sample clean-up demonstrated good performance of the procedure. It was applied for the determination of atenolol in human plasma after oral administration and some pharmacokinetic data were obtained.

  10. Ionic-liquid-based dispersive liquid-liquid microextraction coupled with high-performance liquid chromatography for the forensic determination of methamphetamine in human urine.

    PubMed

    Wang, Ruifeng; Qi, Xiujuan; Zhao, Lei; Liu, Shimin; Gao, Shuang; Ma, Xiangyuan; Deng, Youquan

    2016-07-01

    Determination of methamphetamine in forensic laboratories is a major issue due to its health and social harm. In this work, a simple, sensitive, and environmentally friendly method based on ionic liquid dispersive liquid-liquid microextraction combined with high-performance liquid chromatography was established for the analysis of methamphetamine in human urine. 1-Octyl-3-methylimidazolium hexafluorophosphate with the help of disperser solvent methanol was selected as the microextraction solvent in this process. Various parameters affecting the extraction efficiency of methamphetamine were investigated systemically, including extraction solvent and its volume, disperser solvent and its volume, sample pH, extraction temperature, and centrifugal time. Under the optimized conditions, a good linearity was obtained in the concentration range of 10-1000 ng/mL with determination coefficient >0.99. The limit of detection calculated at a signal-to-noise ratio of 3 was 1.7 ng/mL and the relative standard deviations for six replicate experiments at three different concentration levels of 100, 500, and 1000 ng/mL were 6.4, 4.5, and 4.7%, respectively. Meanwhile, up to 220-fold enrichment factor of methamphetamine and acceptable extraction recovery (>80.0%) could be achieved. Furthermore, this method has been successfully employed for the sensitive detection of a urine sample from a suspected drug abuser.

  11. Ionic liquid crystalline phases in 3-hexadecylimidazolium bromide and binary mixtures with 1-decanol.

    PubMed

    Li, Cuihua; He, Jinhua; Chen, Jiahui; Liu, Jianhong; Zhang, Qianling; Yu, Zhenqiang

    2011-07-15

    3-Hexadecylimidazolium bromide was synthesized and characterized showing formation of thermotropic smectic liquid crystals at temperatures above its melting point from 48.5 to 150.9°C. With decreasing temperature, the peak intensities in XRD patterns increase and full widths at half-maximum decrease, suggesting structural order increases with decreasing temperature. Compared with 1,2-dimethyl-3-hexadecyl-imidazolium bromide and hexafluorophosphate, the IL shows a lower melting point and less degree of chain interdigitation. The main reason is due to a more symmetrical structure and denser assembly of the IL molecules, which results in more steric resistance for the alkyl chain to interdigitate. The self-assembly behavior of the hydrophobic IL in an organic solvent was investigated showing SmA(2) lyotropic liquid crystalline phases. The first-order scattering peak shifts to lower q values with increasing IL content, which is opposite to the shift directions of the binary mixtures of the soluble imidazolium IL and water, indicating a different packing behavior of the hydrophobic IL in 1-decanol.

  12. Thermodynamic modeling of the phase behavior of binary systems of ionic liquids and carbon dioxide with the group contribution equation of state.

    PubMed

    Breure, Bianca; Bottini, Susana B; Witkamp, Geert-Jan; Peters, Cor J

    2007-12-27

    The group contribution equation of state (GC-EOS) was applied to predict the phase behavior of binary systems of ionic liquids of the homologous families 1-alkyl-3-methylimidazolium hexafluorophosphate and tetrafluoroborate with CO2. Pure group parameters for the new ionic liquid functional groups [-mim][PF6] and [-mim][BF4] and interaction parameters between these groups and the paraffin (CH3, CH2) and CO2 groups were estimated. The GC-EOS extended with the new parameters was applied to predict high-pressure phase equilibria in binary mixtures of the ionic liquids [emim][PF6], [bmim][PF6], [hmim][PF6], [bmim][BF4], [hmim][BF4], and [omim][BF4] with CO2. The agreement between experimental and predicted bubble point data for the ionic liquids was excellent for pressures up to 20 MPa, and even for pressures up to about 100 MPa, the agreement was good. The results show the capability of the GC-EOS to describe phase equilibria of systems consisting of ionic liquids.

  13. Investigation of binary and ternary systems of ionic liquids with water and/or supercritical CO2 by in situ attenuated total reflection infrared spectroscopy.

    PubMed

    Andanson, Jean-Michel; Jutz, Fabian; Baiker, Alfons

    2010-02-18

    Two commonly used ionic liquids (ILs), 1-butyl-3-methylimidazolium tetrafluoroborate ([bmim][BF(4)]) and 1-butyl-3-methylimidazolium hexafluorophosphate ([bmim][PF(6)]), as well as binary and ternary mixtures of them with water and/or supercritical CO(2) (scCO(2)) were investigated by means of infrared spectroscopy at high pressure. The experiments were performed using attenuated total reflection (ATR) infrared spectroscopy on dry and wet ILs at 40 degrees C and pressures up to 150 bar of scCO(2). The studies indicate that the content of water does not change significantly the solubility of CO(2) in the ionic liquids tested. Furthermore, the presence of water does not change significantly the interaction between the IL anion and CO(2), which explains why the presence of water in IL does not modify the solubility of CO(2) in the system, even in the case of an initial molar ratio of approximately 50/50 of water in [bmim][BF(4)]. We show that despite the limited solubility of water in supercritical CO(2) an ionic liquid can be efficiently dried using scCO(2) extraction even in the case of a hydrophilic ionic liquid (e.g., [bmim][BF(4)]). During the scCO(2) extraction, the concentration of water was followed in situ using attenuated total reflection (ATR) infrared spectroscopy. After extraction, no residual water could be detected by this technique, which corresponds approximately to a water concentration of below 320 ppm.

  14. Segregation of ions at the interface: molecular dynamics studies of the bulk and liquid-vapor interface structure of equimolar binary mixtures of ionic liquids.

    PubMed

    Palchowdhury, Sourav; Bhargava, B L

    2015-08-14

    The structures of three different equimolar binary ionic liquid mixtures and their liquid-vapor interface have been studied using atomistic molecular dynamics simulations. Two of these binary mixtures were composed of a common cation 1-n-butyl-3-methylimidazolium and varying anions (chloride and hexafluorophosphate in one of the mixtures and chloride and trifluoromethanesulfonate in the other) and the third binary mixture was composed of a common anion, trifluoromethanesulfonate and two imidazolium cations with ethyl and octyl side chains. Binary mixtures with common cations are found to be homogeneous. The anions are preferentially located near the ring hydrogen atoms due to H-bonding interactions. Segregation of ions is observed at the interface with an enrichment of the liquid-vapor interface layer by longer alkyl chains and bigger anions with a distributed charge. The surface composition is drastically different from that of the bulk composition, with the longer alkyl tail groups and bigger anions populating the outermost layer of the interface. The longer alkyl chains of the cations and trifluoromethanesulfonate anions with a smaller charge density show orientational ordering at the liquid-vapor interface.

  15. Interactions of Ionic Liquids with Uranium and its Bioreduction

    SciTech Connect

    Zhang, C.; Francis, A.

    2012-09-18

    We investigated the influence of ionic liquids (ILs) 1-butyl-3-methylimidazolium hexafluorophosphate [BMIM]{sup +}[PF{sub 6}]{sup -}, N-ethylpyridinium trifluoroacetate [EtPy]{sup +}[CF{sub 3}COO]{sup -} and N-ethylpyridinium tetrafluoroborate [Et-Py]{sup +}[BF{sub 4}]{sup -} on uranium reduction by Clostridium sp. under anaerobic conditions. Potentiometric titration, UV-vis spectrophotometry, LC-MS and EXAFS analyses showed monodentate complexation between uranyl and BF{sub 4}{sup -} PF{sub 6}{sup -}; and bidentate complexation with CF{sub 3}COO{sup -}. Ionic liquids affected the growth of Clostridium sp. as evidenced by decrease in optical density, changes in pH, gas production, and the extent of U(VI) reduction and precipitation of U(IV) from solution. Reduction of U(VI) to U(IV) was observed in the presence of [EtPy][BF{sub 4}] and [BMIM][PF{sub 6}] but not with [EtPy][CF{sub 3}COO].

  16. Improvement of the cloud point extraction of uranyl ions by the addition of ionic liquids.

    PubMed

    Gao, Song; Sun, Taoxiang; Chen, Qingde; Shen, Xinghai

    2013-12-15

    The cloud point extraction (CPE) of uranyl ions by different kinds of extractants in Triton X-114 (TX-114) micellar solution was investigated upon the addition of ionic liquids (ILs) with various anions, i.e., bromide (Br(-)), tetrafluoroborate (BF4(-)), hexafluorophosphate (PF6(-)) and bis[(trifluoromethyl)sulfonyl]imide (NTf2(-)). A significant increase of the extraction efficiency was found on the addition of NTf2(-) based ILs when using neutral extractant tri-octylphosphine oxide (TOPO), and the extraction efficiency kept high at both nearly neutral and high acidity. However, the CPE with acidic extractants, e.g., bis(2-ethylhexyl) phosphoric acid (HDEHP) and 8-hydroxyquinoline (8-HQ) which are only effective at nearly neutral condition, was not improved by ILs. The results of zeta potential and (19)F NMR measurements indicated that the anion NTf2(-) penetrated into the TX-114 micelles and was enriched in the surfactant-rich phase during the CPE process. Meanwhile, NTf2(-) may act as a counterion in the CPE of UO2(2+) by TOPO. Furthermore, the addition of IL increased the separation factor of UO2(2+) and La(3+), which implied that in the micelle TOPO, NTf2(-) and NO3(-) established a soft template for UO2(2+). Therefore, the combination of CPE and IL provided a supramolecular recognition to concentrate UO2(2+) efficiently and selectively.

  17. o-, m-, and p-Pyridyl isomer effects on construction of 1D loop-and-chains: Silver(I) coordination polymers with Y-type tridentate ligands

    NASA Astrophysics Data System (ADS)

    Kim, Jeong Gyun; Cho, Yoonjung; Lee, Haeri; Lee, Young-A.; Jung, Ok-Sang

    2016-10-01

    Self-assembly of silver(I) hexafluorophosphate with unique Y-type tridentate ligands (2,6-bis[(2-picolinoyloxy-5-methylphenyl)methyl]-p-tolylpicolinate (o-L), 2-nicotinoyloxy- (m-L), and 2-isonicotinoyloxy- (p-L)) produces single crystals consisting of 1D loop-and-chain coordination polymers of [Ag(o-L)](PF6)·Me2CO·CHCl3, [Ag(m-L)](PF6)·Me2CO, and [Ag3(p-L)2](PF6)3·2H2O·2C2H5OH·4CH2Cl2 with quite different trigonal prismatic, trigonal, and linear silver(I) coordination geometry, respectively. Coordinating ability of the three ligands for AgPF6 is in the order of p-L > o-L > m-L. The solvate molecules of [Ag(o-L)](PF6)·Me2CO·CHCl3 can be removed, and be replaced reversibly in the order of acetone ≫ chloroform ≈ dichloromethane ≫ benzene, without destruction of its skeleton.

  18. Redox-Robust Pentamethylferrocene Polymers and Supramolecular Polymers, and Controlled Self-Assembly of Pentamethylferricenium Polymer-Embedded Ag, AgI, and Au Nanoparticles.

    PubMed

    Gu, Haibin; Ciganda, Roberto; Castel, Patricia; Vax, Amélie; Gregurec, Danijela; Irigoyen, Joseba; Moya, Sergio; Salmon, Lionel; Zhao, Pengxiang; Ruiz, Jaime; Hernández, Ricardo; Astruc, Didier

    2015-12-07

    We report the first pentamethylferrocene (PMF) polymers and the redox chemistry of their robust polycationic pentamethylferricenium (PMFium) analogues. The PMF polymers were synthesized by ring-opening metathesis polymerization (ROMP) of a PMF-containing norbornene derivative by using the third-generation Grubbs ruthenium metathesis catalyst. Cyclic voltammetry studies allowed us to determine confidently the number of monomer units in the polymers through the Bard-Anson method. Stoichiometric oxidation by using ferricenium hexafluorophosphate quantitatively and instantaneously provided fully stable (even in aerobic solutions) blue d(5) Fe(III) metallopolymers. Alternatively, oxidation of the PMF-containing polymers was conducted by reactions with Ag(I) or Au(III) , to give PMFium polymer-embedded Ag and Au nanoparticles (NPs). In the presence of I2 , oxidation by using Ag(I) gave polymer-embedded Ag/AgI NPs and AgNPs at the surface of AgI NPs. Oxidation by using Au(III) also produced an Au(I) intermediate that was trapped and characterized. Engineered single-electron transfer reactions of these redox-robust nanomaterial precursors appear to be a new way to control their formation, size, and environment in a supramolecular way.

  19. Antibody Conjugation Approach Enhances Breadth and Potency of Neutralization of Anti-HIV-1 Antibodies and CD4-IgG

    PubMed Central

    Gavrilyuk, Julia; Ban, Hitoshi; Uehara, Hisatoshi; Sirk, Shannon J.; Saye-Francisco, Karen; Cuevas, Angelica; Zablowsky, Elise; Oza, Avinash; Seaman, Michael S.; Burton, Dennis R.

    2013-01-01

    Broadly neutralizing antibodies PG9 and PG16 effectively neutralize 70 to 80% of circulating HIV-1 isolates. In this study, the neutralization abilities of PG9 and PG16 were further enhanced by bioconjugation with aplaviroc, a small-molecule inhibitor of virus entry into host cells. A novel air-stable diazonium hexafluorophosphate reagent that allows for rapid, tyrosine-selective functionalization of proteins and antibodies under mild conditions was used to prepare a series of aplaviroc-conjugated antibodies, including b12, 2G12, PG9, PG16, and CD4-IgG. The conjugated antibodies blocked HIV-1 entry through two mechanisms: by binding to the virus itself and by blocking the CCR5 receptor on host cells. Chemical modification did not significantly alter the potency of the parent antibodies against nonresistant HIV-1 strains. Conjugation did not alter the pharmacokinetics of a model IgG in blood. The PG9-aplaviroc conjugate was tested against a panel of 117 HIV-1 strains and was found to neutralize 100% of the viruses. PG9-aplaviroc conjugate IC50s were lower than those of PG9 in neutralization studies of 36 of the 117 HIV-1 strains. These results support this new approach to bispecific antibodies and offer a potential new strategy for combining HIV-1 therapies. PMID:23427154

  20. Density functional and neutron diffraction studies of lithium polymer electrolytes.

    SciTech Connect

    Baboul, A. G.

    1998-06-26

    The structure of PEO doped with lithium perchlorate has been determined using neutron diffraction on protonated and deuterated samples. The experiments were done in the liquid state. Preliminary analysis indicates the Li-O distance is about 2.0 {angstrom}. The geometries of a series of gas phase lithium salts [LiCF{sub 3}SO{sub 3}, Li(CF{sub 3}SO{sub 2}){sub 2}N, Li(CF{sub 3}SO{sub 2}){sub 2}CH, LiClO{sub 4}, LiPF{sub 6}, LiAsF{sub 6}] used in polymer electrolytes have been optimized at B3LYP/6-31G(d) density functional level of theory. All local minima have been identified. For the triflate, imide, methanide, and perchlorate anions, the lithium cation is coordinated to two oxygens and have binding energies of ca 141 kcal/mol at the B3LYP/6-311+G(3df,2p)/B3LYP/6-31G* level of theory. For the hexafluoroarsenate and hexafluorophosphate the lithium cation is coordinated to three oxygens and have binding energies of ca. 136 kcal/mol.

  1. Asymmetric hydrolytic kinetic resolution with recyclable macrocyclic Co(III)-salen complexes: a practical strategy in the preparation of (R)-mexiletine and (S)-propranolol.

    PubMed

    Sadhukhan, Arghya; Khan, Noor-ul H; Roy, Tamal; Kureshy, Rukhsana I; Abdi, Sayed H R; Bajaj, Hari C

    2012-04-23

    A chiral cobalt(III) complex (1e) was synthesized by the interaction of cobalt(II) acetate and ferrocenium hexafluorophosphate with a chiral dinuclear macrocyclic salen ligand that was derived from 1R,2R-(-)-1,2-diaminocyclohexane with trigol bis-aldehyde. A variety of epoxides and glycidyl ethers were suitable substrates for the reaction with water in the presence of chiral macrocyclic salen complex 1e at room temperature to afford chiral epoxides and diols by hydrolytic kinetic resolution (HKR). Excellent yields (47% with respect to the epoxides, 53% with respect to the diols) and high enantioselectivity (ee>99% for the epoxides, up to 96% for the diols) were achieved in 2.5-16 h. The Co(III) macrocyclic salen complex (1e) maintained its performance on a multigram scale and was expediently recycled a number of times. We further extended our study of chiral epoxides that were synthesized by using HKR to the synthesis of chiral drug molecules (R)-mexiletine and (S)-propranolol.

  2. Grafting of ionic liquids on stainless steel surface for antibacterial application.

    PubMed

    Pang, Li Qing; Zhong, Li Juan; Zhou, Hui Fang; Wu, Xue E; Chen, Xiao Dong

    2015-02-01

    Stainless steel (SS) is favored for many uses due to its excellent chemical resistance, thermal stability and mechanical properties. Biofilms can be formed on stainless steel and may lead to serious hygiene problems and economic losses in many areas, e.g. food processing, public infrastructure and healthcare. For the first time, our work endeavored to make SS having antibacterial properties, ionic liquids (ILs) were grafted on SS surface via silane treatment followed by thiol-ene click reaction. The chemical structure and composition of the ILs grafted stainless-steel coupon surfaces were characterized by X-ray photoelectron spectroscopy (XPS) and attenuated total reflection-Fourier transform infrared (ATR-FTIR) spectroscopy. The antibacterial activity has been investigated, and the results showed that the ILs grafted SS surface exhibited significant antibacterial effects against Gram-negative Escherichia coli. Additionally, the results obtained here indicated that the ILs used here having bromide anion showed much better antibacterial activity against E. coli than the corresponding ILs with tetrafluoroborate and hexafluorophosphate as anions. These results obtained here can help to design novel and more efficient stainless steel having antibacterial surface.

  3. A Series of Imidazole Derivatives: Synthesis, Two-Photon Absorption, and Application for Bioimaging

    PubMed Central

    Zhu, Yingzhong; Xiao, Lufei; Zhao, Meng; Zhou, Jiazheng; Zhang, Qiong; Wang, Hui; Li, Shengli; Zhou, Hongping; Wu, Jieying; Tian, Yupeng

    2015-01-01

    A new series of D-π-A type imidazole derivatives have been synthesized and characterized. Two corresponding imidazolium salts (iodine and hexafluorophosphate) were prepared from the imidazole compound. Their electron-withdrawing ability can be largely tunable by salt formation reaction or ion exchange. UV-vis absorption and single-photon fluorescence spectra have been systematically investigated in different solvents. The two-photon cross sections (δ2PA) of the imidazole derivatives are measured by two-photon excited fluorescence (2PEF) method. Compared with those of T-1 (107 GM) and T-3 (96 GM), T-2 (imidazolium iodine salt) has a large two-photon absorption (2PA) cross section value of 276 GM. Furthermore, the cytotoxicity and applications in bioimaging for the imidazole derivatives were carried out. The results showed that T-1 can be used as a lysosomal tracker with high stability and water solubility within pHs of 4–6, while T-2 and T-3 can be used as probes for cell cytoplasm. PMID:26579544

  4. Highly Functionalized Cyclopentane Derivatives by Tandem Michael Addition/Radical Cyclization/Oxygenation Reactions.

    PubMed

    Holan, Martin; Pohl, Radek; Císařová, Ivana; Klepetářová, Blanka; Jones, Peter G; Jahn, Ullrich

    2015-06-26

    Densely functionalized cyclopentane derivatives with up to four consecutive stereocenters are assembled by a tandem Michael addition/single-electron transfer oxidation/radical cyclization/oxygenation strategy mediated by ferrocenium hexafluorophosphate, a recyclable, less toxic single-electron transfer oxidant. Ester enolates were coupled with α-benzylidene and α-alkylidene β-dicarbonyl compounds with switchable diastereoselectivity. This pivotal steering element subsequently controls the diastereoselectivity of the radical cyclization step. The substitution pattern of the radical cyclization acceptor enables a switch of the cyclization mode from a 5-exo pattern for terminally substituted olefin units to a 6-endo mode for internally substituted acceptors. The oxidative anionic/radical strategy also allows efficient termination by oxygenation with the free radical 2,2,6,6-tetramethyl-1-piperidinoxyl, and two C-C bonds and one C-O bond are thus formed in the sequence. A stereochemical model is proposed that accounts for all of the experimental results and allows the prediction of the stereochemical outcome. Further transformations of the synthesized cyclopentanes are reported.

  5. Magnetic stirrer induced dispersive ionic-liquid microextraction for the determination of vanadium in water and food samples prior to graphite furnace atomic absorption spectrometry.

    PubMed

    Naeemullah; Kazi, Tasneem Gul; Tuzen, Mustafa

    2015-04-01

    A new dispersive liquid-liquid microextraction, magnetic stirrer induced dispersive ionic-liquid microextraction (MS-IL-DLLME) was developed to quantify the trace level of vanadium in real water and food samples by graphite furnace atomic absorption spectrometry (GFAAS). In this extraction method magnetic stirrer was applied to obtained a dispersive medium of 1-butyl-3-methylimidazolium hexafluorophosphate [C4MIM][PF6] in aqueous solution of (real water samples and digested food samples) to increase phase transfer ratio, which significantly enhance the recovery of vanadium - 4-(2-pyridylazo) resorcinol (PAR) chelate. Variables having vital role on desired microextraction methods were optimised to obtain the maximum recovery of study analyte. Under the optimised experimental variables, enhancement factor (EF) and limit of detection (LOD) were achieved to be 125 and 18 ng L(-1), respectively. Validity and accuracy of the desired method was checked by analysis of certified reference materials (SLRS-4 Riverine water and NIST SRM 1515 Apple leaves). The relative standard deviation (RSD) for 10 replicate determinations at 0.5 μg L(-1) of vanadium level was found to be <5.0%. This method was successfully applied to real water and acid digested food samples.

  6. Development of a new green non-dispersive ionic liquid microextraction method in a narrow glass column for determination of cadmium prior to couple with graphite furnace atomic absorption spectrometry.

    PubMed

    Naeemullah; Kazi, Tasneem Gul; Tuzen, Mustafa; Shah, Faheem; Afridi, Hassan Imran; Citak, Demirhan

    2014-02-17

    Easy and innovative non-dispersive ionic liquid based microextraction (NDILME) has been developed for preconcentration of trace level of cadmium (Cd) in aqueous real surface water samples prior to couple with graphite furnace atomic absorption spectrometry (GFAAS). A 200 cm long narrow glass column containing aqueous solution of standard/sample was used to increase phase transfer ratio by providing more contact area between two medium (aqueous and extractive), which drastically improve the recoveries of labile hydrophobic chelate of Cd ammonium pyrrolidinedithiocarbamate (APDC), into ionic liquid 1-butyl-3-methylimidazolium hexafluorophosphate [C4mim][PF6]. Different aspect of the desire method have been investigated and optimized. Under the optimized key experimental variables, limit of detection (LOD) and enhancement factor (EF) were achieved to be 0.5 ng L(-1) and 150, respectively. Reliability of the model method was checked by relative standard deviation (%RSD), which was found to be <5%. Validity and accuracy of the developed method was checked by analysis of certified reference water samples (SLRS-4 Riverine water) using standard addition method. Application of the model method was productively performed by analysis of Cd in real surface water samples (tap and sea).

  7. Monitoring charge storage processes in nanoscale oxides using electrochemical scanning probe microscopy.

    SciTech Connect

    Zavadil, Kevin Robert; Lu, Ping; Huang, Jian Yu

    2010-11-01

    Advances in electrochemical energy storage science require the development of new or the refinement of existing in situ probes that can be used to establish structure - activity relationships for technologically relevant materials. The drive to develop reversible, high capacity electrodes from nanoscale building blocks creates an additional requirement for high spatial resolution probes to yield information of local structural, compositional, and electronic property changes as a function of the storage state of a material. In this paper, we describe a method for deconstructing a lithium ion battery positive electrode into its basic constituents of ion insertion host particles and a carbon current collector. This model system is then probed in an electrochemical environment using a combination of atomic force microscopy and tunneling spectroscopy to correlate local activity with morphological and electronic configurational changes. Cubic spinel Li{sub 1+x}Mn{sub 2-x}O{sub 4} nanoparticles are grown on graphite surfaces using vacuum deposition methods. The structure and composition of these particles are determined using transmission electron microscopy and Auger microprobe analysis. The response of these particles to initial de-lithiation, along with subsequent electrochemical cycling, is tracked using scanning probe microscopy techniques in polar aprotic electrolytes (lithium hexafluorophosphate in ethylene carbonate:diethylcarbonate). The relationship between nanoparticle size and reversible ion insertion activity will be a specific focus of this paper.

  8. A Highly Reversible Room-Temperature Sodium Metal Anode

    PubMed Central

    2015-01-01

    Owing to its low cost and high natural abundance, sodium metal is among the most promising anode materials for energy storage technologies beyond lithium ion batteries. However, room-temperature sodium metal anodes suffer from poor reversibility during long-term plating and stripping, mainly due to formation of nonuniform solid electrolyte interphase as well as dendritic growth of sodium metal. Herein we report for the first time that a simple liquid electrolyte, sodium hexafluorophosphate in glymes (mono-, di-, and tetraglyme), can enable highly reversible and nondendritic plating–stripping of sodium metal anodes at room temperature. High average Coulombic efficiencies of 99.9% were achieved over 300 plating–stripping cycles at 0.5 mA cm–2. The long-term reversibility was found to arise from the formation of a uniform, inorganic solid electrolyte interphase made of sodium oxide and sodium fluoride, which is highly impermeable to electrolyte solvent and conducive to nondendritic growth. As a proof of concept, we also demonstrate a room-temperature sodium–sulfur battery using this class of electrolytes, paving the way for the development of next-generation, sodium-based energy storage technologies. PMID:27163006

  9. Cladribine Analogues via O6-(Benzotriazolyl) Derivatives of Guanine Nucleosides

    PubMed Central

    Satishkumar, Sakilam; Vuram, Prasanna K.; Relangi, Siva Subrahmanyam; Gurram, Venkateshwarlu; Zhou, Hong; Kreitman, Robert J.; Montemayor, Michelle M. Martínez; Yang, Lijia; Kaliyaperumal, Muralidharan; Sharma, Somesh; Pottabathini, Narender; Lakshman, Mahesh K.

    2016-01-01

    Cladribine, 2-chloro-2′-deoxyadenosine, is a highly efficacious clinically used nucleoside for the treatment of hairy cell leukemia. It is also being evaluated against other lymphoid malignancies and has been a molecule of interest for well over half a century. In continuation of our interest on the amide bond-activation in purine nucleosides via the use of (benzotriazol-1yl-oxy)tris(dimethylamino)phosphonium hexafluorophosphate, we have evaluated the use of O6-(benzotriazol-1-yl)-2′-deoxyguanosine as a potential precursor to cladribine and its analogues. These compounds, after appropriate deprotection, were assessed for their biological activities and the data are presented herein. Against hairy cell leukemia (HCL), T-cell lymphoma (TCL), and chronic lymphocytic leukemia (CLL) cladribine was the most active against all. The bromo analogue of cladribine showed comparable activity to the ribose analogue of cladribine against HCL, but was more active against TCL and CLL. The bromo ribo analogue of cladribine possessed activity, but was least active among the C6-NH2-containing compounds. Substitution with alkyl groups at the exocyclic amino group appears detrimental to activity, and only the C6 piperidinyl cladribine analogue demonstrated any activity. Against adenocarcinoma MDA-MB-231 cells, only cladribine and its ribose analogue were most active. PMID:26556315

  10. Towards more thermally stable Li-ion battery electrolytes with salts and solvents sharing nitrile functionality

    NASA Astrophysics Data System (ADS)

    Kerner, Manfred; Lim, Du-Hyun; Jeschke, Steffen; Rydholm, Tomas; Ahn, Jou-Hyeon; Scheers, Johan

    2016-11-01

    The overall safety of Li-ion batteries is compromised by the state-of-the-art electrolytes; the thermally unstable lithium salt, lithium hexafluorophosphate (LiPF6), and flammable carbonate solvent mixtures. The problem is best addressed by new electrolyte compositions with thermally robust salts in low flammability solvents. In this work we introduce electrolytes with either of two lithium nitrile salts, lithium 4,5-dicyano-1,2,3-triazolate (LiDCTA) or lithium 4,5-dicyano-2-trifluoromethylimidazolide (LiTDI), in solvent mixtures with high flashpoint adiponitrile (ADN), as the main component. With sulfolane (SL) and ethylene carbonate (EC) as co-solvents the liquid temperature range of the electrolytes are extended to lower temperatures without lowering the flashpoint, but at the expense of high viscosities and moderate ionic conductivities. The anodic stabilities of the electrolytes are sufficient for LiFePO4 cathodes and can be charged/discharged for 20 cycles in Li/LiFePO4 cells with coulombic efficiencies exceeding 99% at best. The excellent thermal stabilities of the electrolytes with the solvent combination ADN:SL are promising for future electrochemical investigations at elevated temperatures (> 60 °C) to compensate the moderate transport properties and rate capability. The electrolytes with EC as a co-solvent, however, release CO2 by decomposition of EC in presence of a lithium salt, which potentially makes EC unsuitable for any application targeting higher operating temperatures.

  11. Ionic liquid-based dispersive liquid-liquid microextraction with back-extraction coupled with capillary electrophoresis to determine phenolic compounds.

    PubMed

    Zhou, Caihong; Tong, Shanshan; Chang, Yunxia; Jia, Qiong; Zhou, Weihong

    2012-04-01

    Ionic liquid (IL) based dispersive liquid-liquid microextraction (DLLME) with back-extraction coupled with capillary electrophoresis ultraviolet detection was developed to determine four phenolic compounds (bisphenol-A, β-naphthol, α-naphthol, 2, 4-dichlorophenol) in aqueous cosmetics. The developed method was used to preconcentrate and clean up the four phenolic compounds including two steps. The analytes were transferred into room temperature ionic liquid (1-octyl-3-methylimidazolium hexafluorophosphate, [C(8) MIM][PF(6) ]) rich-phase in the first step. In the second step, the analytes were back-extracted into the alkaline aqueous phase. The effects of extraction parameters, such as type and volume of extraction solvent, type and volume of disperser, extraction and centrifugal time, sample pH, salt addition, and concentration and volume of NaOH in back-extraction were investigated. Under the optimal experimental conditions, the preconcentration factors were 60.1 for bisphenol-A, 52.7 for β-naphthol, 49.2 for α-naphthol, and 18.0 for 2, 4-dichlorophenol. The limits of detection for bisphenol-A, β-naphthol, α-naphthol and 2, 4-dichlorophenol were 5, 5, 8, and 100 ng mL(-1), respectively. Four kinds of aqueous cosmetics including toner, soften lotion, make-up remover, and perfume were analyzed and yielded recoveries ranging from 81.6% to 119.4%. The main advantages of the proposed method are quick, easy, cheap, and effective.

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

    PubMed

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

    2013-03-21

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

  13. Lattice dynamics, phase transitions and spin relaxation in [Fe(C5H5)2] PF6

    NASA Astrophysics Data System (ADS)

    Herber, R. H.; Felner, I.; Nowik, I.

    2016-12-01

    The organometallic compound ferrocenium hexafluorophosphate, [Fe(C5H5)2] PF6, has been studied by Mössbauer spectroscopy in the past, mainly to determine the crystal structure at high temperatures. Here we present studies at 95 K to 305 K and analyze the spectra in terms of spin relaxation theory which yields accurately the hyperfine interaction parameters and the spin-spin and spin-lattice relaxation rates in this paramagnetic compound. The spectral area under the resonance curve yields the recoil free fraction and thus the mean square of the vibration amplitude . One observes a large discontinuity in the slope of versus T at ˜210 K, indicative of a phase transition. The analysis of the spectra proves that the quadrupole interaction is small but certainly negative, ½e2qQ = -0.12(2) mm/s, and causes the asymmetry observed in the spectra. The detailed analysis yields also, for the first time, the fluctuating effective magnetic hyperfine field, H eff = 180(50) kOe.

  14. Conducting-polymer-driven actively shaped propellers and screws

    NASA Astrophysics Data System (ADS)

    Madden, John D.; Schmid, Bryan; Lafontaine, Serge R.; Madden, Peter G. A.; Hover, Franz S.; McLetchie, Karl; Hunter, Ian W.

    2003-07-01

    Conducting polymer actuators are employed to create actively shaped hydrodynamic foils. The active foils are designed to allow control over camber, much like the ailerons of an airplane wing. Control of camber promises to enable variable thrust in propellers and screws, increased maneuverability, and improved stealth. The design and fabrication of the active foils are presented, the forces are measured and operation is demonstrated both in still air and water. The foils have a "wing" span of 240 mm, and an average chord length (width) of 70 mm. The trailing 30 mm of the foil is composed of a thin polypyrrole actuator that curls chordwise to achieve variable camber. The actuator consists of two 30 μm thick sheets of hexafluorophosphate doped polypyrrole separated from each other by a gel electrolyte. A polymer layer encapsulates the entire structure. Potentials are applied between the polymer layers to induce reversible bending by approximately 35 degrees, and generating forces of 0.15 N. These forces and displacements are expected to enable operation in water at flow rates of > 1 m/s and ~ 30 m/s in air.

  15. Chemical stability of Lithium 2-trifluoromethyl-4,5-dicyanoimidazolide, an electrolyte salt for Li-ion cells

    DOE PAGES

    Shkrob, Ilya A.; Pupek, Krzysztof Z.; Gilbert, James A.; ...

    2016-12-01

    Lithium hexafluorophosphate (LiPF6) is ubiquitous in commercial lithium-ion batteries, but it is hydrolytically unstable and corrosive on electrode surfaces. Using a more stable salt would confer multiple benefits for high-voltage operation, but many such electrolyte systems facilitate anodic dissolution and pitting corrosion of aluminum current collectors that negate their advantages. Lithium 2-trifluoromethyl-4,5-dicyanoimidazolide (LiTDI) is a new salt that was designed specifically for high-voltage cells. In this study we demonstrate that in carbonate electrolytes, LiTDI prevents anodic dissolution of Al current collectors, which places it into a select group of corrosion inhibitors. However, we also demonstrate that LiTDI becomes reduced onmore » lithiated graphite, undergoing sequential defluorination and yielding a thick and resistive solid-electrolyte interphase (SEI), which increases impedance and lowers electrode capacity. The mechanistic causes for this behavior are examined using computational chemistry methods in the light of recent spectroscopic studies. Here, we demonstrate that LiTDI reduction can be prevented by certain electrolyte additives, which include fluoroethylene carbonate, vinylene carbonate and lithium bis(oxalato)borate. This beneficial action is due to preferential reduction of these additives over LiTDI at a higher potential vs. Li/Li+, so the resulting SEI can prevent the direct reduction of LiTDI at lower potentials on the graphite electrode.« less

  16. Voltammetry of redox analytes at trace concentrations with nanoelectrode ensembles.

    PubMed

    Moretto, Ligia Maria; Pepe, Niki; Ugo, Paolo

    2004-04-19

    Gold nanoelectrodes ensembles (NEEs) have been prepared by electroless plating of Au nanoelectrode elements within the pores of a microporous polycarbonate template membrane. Cyclic voltammograms recorded in (ferrocenylmethyl) trimethylammonium hexafluorophosphate (FA(+) PF(6)(-)) solutions showed that these NEEs operate in the "total-overlap" response regime, giving well resolved peak shaped voltammograms. Experimental results show that the faradaic/background currents ratios at the NEE are independent on the total geometric area of the ensemble, so that NEE can be enlarged or miniaturized at pleasure without influencing the very favorable signal/noise ratio. Differential pulse voltammetry (DPV) at the NEE is optimized for direct determinations at trace levels. DPV at NEE allowed the determination (with no preconcentration) of trace amounts of FA(+), with a detection limit of 0.02muM. The use of NEE and DPV in cytochrome c (cyt c) solutions showed the possibility to observe the direct electrochemistry of submicromolar concentration of the protein, even without the need of adding any promoter or mediator.

  17. Surface modification using ionic liquid ion beams

    NASA Astrophysics Data System (ADS)

    Takaoka, Gikan H.; Hamaguchi, Takuya; Takeuchi, Mitsuaki; Ryuto, Hiromichi

    2014-12-01

    We developed an ionic liquid (IL) ion source using 1-butyl-3-methylimidazolium hexafluorophosphate (BMIM-PF6) and produced IL ion beams by applying a high electric field between the tip and the extractor. Time-of-flight measurements showed that small cluster and fragment ions were contained in the positive and negative ion beams. The positive and negative cluster ions were deposited on Si(1 0 0) substrates. X-ray photoelectron spectroscopy measurements showed that the composition of the deposited layers was similar to that of an IL solvent. This suggests that a cation (A+) or an anion (B-) was attached to an IL cluster (AB)n, resulting in the formation of positive cluster ions (AB)nA+ or negative cluster ions (AB)nB-, respectively. The surfaces of the IL layers deposited on Si(1 0 0) substrates were flat at an atomic level for positive and negative cluster ion irradiation. Moreover, the contact angles of the deposited layers were similar to that of the IL solvent. Thus, surface modification of Si(1 0 0) substrates was successfully demonstrated with BMIM-PF6 cluster ion beams.

  18. Environmentally friendly ionic liquid-in-water microemulsions for extraction of hydrophilic and lipophilic components from Flos Chrysanthemi.

    PubMed

    Chen, Jue; Cao, Jun; Gao, Wen; Qi, Lian-Wen; Li, Ping

    2013-10-21

    Ionic liquids (ILs) have numerous chemical applications as environmentally green solvents that are extending into microemulsion applications. In this work, a novel benign IL-in-water microemulsion system modified by an IL surfactant has been proposed for simultaneous extraction of hydrophilic and lipophilic constituents from Flos Chrysanthemi (Chrysanthemum morifolium). Constituents were analyzed by rapid-resolution liquid chromatography coupled with quadrupole time-of-flight mass spectrometry. A mixture-design approach was used to optimize the IL surfactant and the IL oil phase in the microemulsion system. Microemulsions consisting of 6.0% 1-dodecyl-3-methylimidazolium hydrogen sulfate, 0.1% 1-vinyl-3-methylimidazolium hexafluorophosphate and 93.9% water offered the acceptable extract efficiency that are comparable to or even better than conventional volatile organic solvents. This assay was fully validated with respect to the linearity of response (r(2) > 0.999 over two orders of magnitude), precision (intra-RSD < 0.49 and inter-day RSD < 2.21), and accuracy (recoveries ranging from 93.73% to 101.84%). The proposed IL-in-water microemulsion method provided an environmentally friendly alternative for efficient extraction of compounds from Flos Chrysanthemi and could be extended to complex environmental and pharmaceutical samples.

  19. Dielectric spectroscopy study on ionic liquid microemulsion composed of water, TX-100, and BmimPF6

    NASA Astrophysics Data System (ADS)

    Chen, Zhen; Nozaki, Ryusuke

    2012-06-01

    We report here a broadband dielectric spectroscopy study on an ionic liquid microemulsion (ILM) composed of water, Triton X-100 (TX-100), and 1-butyl-3-methylimidazolium hexafluorophosphate (bmimPF6). It is found that the phase behavior of this ILM can be easily identified by its dielectric response. The dielectric behavior of the ILM in the GHz range is consistent with that of TX-100/water mixtures with comparable water-to-TX-100 weight ratio. It consists of the relaxations due to ethylene oxide (EO) unit relaxation, hydration water dynamics, and/or free water dynamics. The water content dependence of the EO unit relaxation suggests that this relaxation involves dynamics of hydration water molecules. In the IL-in-water microemulsion phase, it is found that bmimPF6 molecules are preferentially dissolved in water when their concentration in water is lower than the solubility. An additional dielectric relaxation that is absent in the TX-100/water mixtures is observed in the frequency range of 107-108 Hz for this ILM. This low-frequency relaxation is found closely related to the bmimPF6 molecule and could be attributed to the hopping of its cations/anions between the anionic/cationic sites.

  20. Self-assembled inverted micelles stabilize ionic liquid domains in supercritical CO2.

    PubMed

    Chandran, Aneesh; Prakash, Karthigeyan; Senapati, Sanjib

    2010-09-08

    Molecular aggregation is a complex phenomenon that is difficult to study in detail experimentally. Here, we elucidate the formation of ionic liquid-in-carbon dioxide (IL-in-CO(2)) microemulsions via a computer simulation technique that demonstrates the entire process of self-aggregation at the atomic level. Our study reveals direct evidence of the existence of stable IL droplets within a continuous CO(2) phase through amphiphilic surfactants. The microstructure of the nanodroplets matches very well with the small-angle neutron scattering data. A detailed investigation of the structural and energetic properties explains why guanidium acetate-based IL-in-CO(2) microemulsions showed a greater stability than imidazolium hexafluorophosphate-based microemulsions in recent spectroscopic experiments. In contrast to the existing hypothesis in literature, the study reveals that the stability of the microemulsions mainly pertains to the IL anion-headgroup interactions, while the cations play a secondary role. The detailed atomic level understanding provides a deeper insight that could help in designing new surfactants for improved IL uptake in CO(2).

  1. Evidence of water-in-ionic liquid microemulsion formation by nonionic surfactant Brij-35.

    PubMed

    Rai, Rewa; Pandey, Siddharth

    2014-09-02

    Brij-35, a common and popular nonionic surfactant, is shown to form water-in-ionic liquid (w/IL) microemulsions with IL 1-butyl-3-methylimidazolium hexafluorophosphate ([bmim][PF6]) as the bulk phase. The presence of w/[bmim][PF6] microemulsions is hinted by the significantly increased solubility of water in Brij-35 solution of [bmim][PF6]. The formation of w/[bmim][PF6] microemulsions by Brij-35 is confirmed using dynamic light scattering (DLS) and small-angle X-ray scattering (SAXS) measurements. Brij-35 forms reverse micelle-type aggregates within [bmim][PF6] in the absence of added-water. These reverse micelles become w/[bmim][PF6] microemulsions as the water is added to the system. As the water loading (w0) is increased, the average diameter of the aggregates increases. Fourier transform infrared (FTIR) absorbance data reveal the presence of both "bound" and "free" water within the system. The "bound" water is associated with the water pools of the w/[bmim][PF6] microemulsions. Excited-state proton transfer (ESPT) involving probe pyranine shows deprotonation of pyranine within the water pools of the w/[bmim][PF6] microemulsions.

  2. Shape and size controlled synthesis of MOF nanocrystals with the assistance of ionic liquid mircoemulsions.

    PubMed

    Shang, Wenting; Kang, Xinchen; Ning, Hui; Zhang, Jianling; Zhang, Xiaogang; Wu, Zhonghua; Mo, Guang; Xing, Xueqing; Han, Buxing

    2013-10-29

    In this work, the La-metal-organic frameworks (La-MOFs) were synthesized using lanthanum(III) nitrate and 1,3,5-benzenetricarboxylic acid (BTC) in H2O-in-1-butyl-3-methylimidazolium hexafluorophosphate (bmimPF6), bmimPF6-in-water, and the bicontinuous microemulsions stabilized by surfactant TX-100. The MOFs prepared were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), powder X-ray diffraction (XRD), thermal gravimetric analysis (TGA), and FT-IR methods, and the microstructures of the microemulsions in the H2O/bmimPF6/TX-100 system were studied by small-angle X-ray scattering (SXAS) technique. It was shown that the dispersed droplets in the water-in-bmimPF6, bicontinuous and bmimPF6-in-water microemulsions were spherical, lamellar, and cylindrical, respectively. The shapes of the La-MOFs synthesized were similar to that of the droplets in the corresponding microemulsions. This indicated that the morphology of MOFs could be controlled by the microstructures of the microemulsions. On the basis of the systematic experimental results, the mechanism for controlling the morphology of the MOFs was proposed.

  3. Role of the surfactant structure in the behavior of hydrophobic ionic liquids within aqueous micellar solutions.

    PubMed

    Behera, Kamalakanta; Kumar, Vinod; Pandey, Siddharth

    2010-04-06

    The behavior of an ionic liquid (IL) within aqueous micellar solutions is governed by its unique property to act as both an electrolyte and a cosolvent. The influence of the surfactant structure on the properties of aqueous micellar solutions of zwitterionic SB-12, nonionic Brij-35 and TX-100, and anionic sodium dodecyl sulfate (SDS) in the presence of the "hydrophobic" IL 1-butyl-3-methylimidazolium hexafluorophosphate ([bmim][PF(6)]) is assessed along with the possibility of forming oil-in-water microemulsions in which the IL acts as the "oil" phase. The solubility of [bmim][PF(6)] within aqueous micellar solutions increases with increasing surfactant concentration. In contrast to anionic SDS, the zwitterionic and nonionic surfactant solutions solubilize more [bmim][PF(6)] at higher concentrations and the average aggregate size remains almost unchanged. The formation of IL-in-water microemulsions when the concentration of [bmim][PF(6)] is above its aqueous solubility is suggested for nonionic Brij-35 and TX-100 aqueous surfactant solutions.

  4. Transport properties of aqueous ionic liquid microemulsions: influence of the anion type and presence of the cosurfactant.

    PubMed

    Piekart, Jakub; Łuczak, Justyna

    2015-12-14

    Transport properties, viz. specific conductivity, dynamic viscosity and apparent diffusion coefficients, were measured as a function of water content in aqueous ionic liquid microemulsions containing 1-butyl-3-methylimidazolium hexafluorophosphate, [BMIM][PF6] and bis(trifluoromethanesulphonyl)imide, [BMIM][Tf2N], stabilized by the nonionic surfactant TX-100, or its mixture with a cosurfactant, i.e. butanol. The investigation covered the whole water content range through various (Winsor I-III and dissolved solution) structures of the system. The comparative approach allowed closer inspection into phenomena being on the background of observed transport properties behavior taking into account the influence of the cosurfactant. The addition of butanol offers considerable advantages, such as an increase in conductivity, especially in systems containing ionic liquids with lower conductivity. This is accompanied by a significant decrease in viscosity, even to values that are comparable with those of molecular solvents. Moreover, the reasons for the surprisingly higher conductivity of [BMIM][PF6]-based systems were provided, and the conclusions were supported by cyclic voltammetry as well as spectrophotometric and dynamic light scattering measurements.

  5. In Situ Measurement of Solid Electrolyte Interphase Evolution on Silicon Anodes Using Atomic Force Microscopy

    SciTech Connect

    Yoon, Insun; Abraham, Daniel P.; Lucht, Brett L.; Bower, Allan F.; Guduru, Pradeep R.

    2016-04-18

    In situ measurements of the growth of solid electrolyte interphase (SEI) layer on silicon and the lithiation-induced volume changes in silicon in lithium ion half-cells are reported. Thin film amorphous silicon electrodes are fabricated in a configuration that allows unambiguous separation of the total thickness change into contribution from SEI thickness and silicon volume change. Electrodes are assembled into a custom-designed electrochemical cell, which is integrated with an atomic force microscope. The electrodes are subjected to constant potential lithiation/delithiation at a sequence of potential values and the thickness measurements are made at each potential after equilibrium is reached. Experiments are carried out with two electrolytes—1.2 m lithium hexafluoro-phosphate (LiPF6) in ethylene carbonate (EC) and 1.2 m LiPF6 in propylene carbonate (PC)—to investigate the influence of electrolyte composition on SEI evolution. It is observed that SEI formation occurs predominantly during the first lithiation and the maximum SEI thickness is ≈17 and 10 nm respectively for EC and PC electrolytes. This study also presents the measured Si expansion ratio versus equilibrium potential and charge capacity versus equilibrium potential; both relationships display hysteresis, which is explained in terms of the stress–potential coupling in silicon.

  6. How the structures of salts involve in the optical properties of Pyrene (C16H10) ?

    NASA Astrophysics Data System (ADS)

    Jang, Hyun-Sook; Zhao, Jing; Nieh, Mu-Ping

    2014-03-01

    Pyrene (Py), due to its specific optical properties (i.e., long life time, excimer, polarity), has been used as a variety of sensors. It has reported that the high vapor pressure in processing the films is an important factor for the enhanced Py optical properties. In this paper, the effects of a series of tetraalkylammonium salts (with a variety of chain lengths and anions) on Py optical properties are investigated in order to identify the controlling parameters of the Py fluorescence quenching in the binary system from the solution to solid state. Several experimental approaches including steady-state fluorescence spectroscopy, 13C-NMR, and time-dependent fluorescence decay are employed in order to seek for the fundamental understanding of the optical properties of Py. The result shows that cation chain length of tetrabutylammonium (TBA +) and hexafluorophosphate (PF6-) anion play an important role in the Py optical properties. These interaction between Py and salts is mainly governed by dynamic quenching processes. The knowledge obtained in this study provides insights to the design of the molecular self-assembly for the development of sensors with high performance.

  7. Extraction behavior of divalent metal cations in ionic liquid chelate extraction systems using 1-alkyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imides and thenoyltrifluoroacetone.

    PubMed

    Kidani, Keiji; Hirayama, Naoki; Imura, Hisanori

    2008-10-01

    The extraction behavior of several divalent metal cations (M(2+)) in ionic liquid chelate extraction systems was investigated using several 1-alkyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide ionic liquids ([Rmim][Tf(2)N]) as extraction solvent and thenoyltrifluoroacetone (Htta) as extractant. The behavior was compared with that using less hydrophobic 1-alkyl-3-methylimidazolium hexafluorophosphates ([Rmim][PF(6)]). The extracted species in the [Rmim][Tf(2)N] systems were neutral M(tta)(2) for M = Cu and anionic M(tta)(3)(-) for M = Mn, Co, Ni, Zn and Cd. Conversion of ionic liquid anion from PF(6)(-) to more hydrophobic Tf(2)N(-) resulted in changing the species extracted for Ni(2+) from hydrated neutral complex to hydrophobic anionic one. Furthermore, the extractability for these metals was governed by the hydrophobicity of ionic liquid ions. Thus, in the ionic liquid chelate extraction system, selection of a suitable ionic liquid as extraction phase seems to be an important factor for enhancement of extraction selectivity.

  8. Comprehensive Insights into the Reactivity of Electrolytes Based on Sodium Ions.

    PubMed

    Eshetu, Gebrekidan Gebresilassie; Grugeon, Sylvie; Kim, Huikyong; Jeong, Sangsik; Wu, Liming; Gachot, Gregory; Laruelle, Stephane; Armand, Michel; Passerini, Stefano

    2016-03-08

    We report a systematic investigation of Na-based electrolytes that comprise various NaX [X=hexafluorophosphate (PF6 ), perchlorate (ClO4 ), bis(trifluoromethanesulfonyl)imide (TFSI), fluorosulfonyl-(trifluoromethanesulfonyl)imide (FTFSI), and bis(fluorosulfonyl)imide (FSI)] salts and solvent mixtures [ethylene carbonate (EC)/dimethyl carbonate (DMC), EC/diethyl carbonate (DEC), and EC/propylene carbonate (PC)] with respect to the Al current collector stability, formation of soluble degradation compounds, reactivity towards sodiated hard carbon (Nax -HC), and solid-electrolyte interphase (SEI) layer formation. Cyclic voltammetry demonstrates that the stability of Al is highly influenced by the nature of the anions, solvents, and additives. GC-MS analysis reveals that the formation of SEI telltales depends on the nature of the linear alkyl carbonates and the battery chemistry (Li(+) vs. Na(+) ). FTIR spectroscopy shows that double alkyl carbonates are the main components of the SEI layer on Nax -HC. In the presence of Na salts, EC/DMC and EC/DEC presented a higher reactivity towards Nax -HC than EC/PC. For a fixed solvent mixture, the onset temperature follows the sequence NaClO4

  9. Solvents and supporting electrolytes for vanadium acetylacetonate flow batteries

    NASA Astrophysics Data System (ADS)

    Shinkle, Aaron A.; Pomaville, Timothy J.; Sleightholme, Alice E. S.; Thompson, Levi T.; Monroe, Charles W.

    2014-02-01

    Properties of supporting electrolytes and solvents were examined for use with vanadium acetylacetonate - a member of the class of metal(β-diketonate) active species - in non-aqueous redox flow batteries. Twenty supporting-electrolyte/solvent combinations were screened for ionic conductivity and supporting-electrolyte solubility. Hexane, tetrahydrofuran, and dimethylcarbonate solvents did not meet minimal conductivity and solubility criteria for any of the electrolytes used, which included tetraethylammonium tetrafluoroborate, tetrabutylammonium tetrafluoroborate, tetrabutylammonium hexafluorophosphate, and (1-butyl, 3-methyl)imidazolium bis(trifluoromethanesulfonyl)imide. Ionic conductivities and solubilities for solutions of these electrolytes passed screening criteria in acetonitrile and dimethylformamide solvents, in which maximum supporting-electrolyte and active-species solubilities were determined. Active-species electrochemistry was found to be reversible in several solvent/support systems; for some systems the voltammetric signatures of unwanted side reactions were suppressed. Correlations between supporting-solution properties and performance metrics suggest that an optimal solvent for a vanadium acetylacetonate RFB should have a low solvent molar volume for active-species solubility, and a high Hansen polarity for conductivity.

  10. Rapid characterization of lithium ion battery electrolytes and thermal aging products by low-temperature plasma ambient ionization high-resolution mass spectrometry.

    PubMed

    Vortmann, Britta; Nowak, Sascha; Engelhard, Carsten

    2013-03-19

    Lithium ion batteries (LIBs) are key components for portable electronic devices that are used around the world. However, thermal decomposition products in the battery reduce its lifetime, and decomposition processes are still not understood. In this study, a rapid method for in situ analysis and reaction monitoring in LIB electrolytes is presented based on high-resolution mass spectrometry (HR-MS) with low-temperature plasma probe (LTP) ambient desorption/ionization for the first time. This proof-of-principle study demonstrates the capabilities of ambient mass spectrometry in battery research. LTP-HR-MS is ideally suited for qualitative analysis in the ambient environment because it allows direct sample analysis independent of the sample size, geometry, and structure. Further, it is environmental friendly because it eliminates the need of organic solvents that are typically used in separation techniques coupled to mass spectrometry. Accurate mass measurements were used to identify the time-/condition-dependent formation of electrolyte decomposition compounds. A LIB model electrolyte containing ethylene carbonate and dimethyl carbonate was analyzed before and after controlled thermal stress and over the course of several weeks. Major decomposition products identified include difluorophosphoric acid, monofluorophosphoric acid methyl ester, monofluorophosphoric acid dimethyl ester, and hexafluorophosphate. Solvents (i.e., dimethyl carbonate) were partly consumed via an esterification pathway. LTP-HR-MS is considered to be an attractive method for fundamental LIB studies.

  11. Thermal stability of LiPF 6 salt and Li-ion battery electrolytes containing LiPF 6

    NASA Astrophysics Data System (ADS)

    Yang, Hui; Zhuang, Guorong V.; Ross, Philip N.

    The thermal stability of the neat lithium hexafluorophosphate (LiPF 6) salt and of 1 molal (m) solutions of LiPF 6 in prototypical Li-ion battery solvents was studied with thermogravimetric analysis (TGA) and on-line Fourier transform infrared (FTIR). Pure LiPF 6 salt is thermally stable up to 107 °C in a dry inert atmosphere, and its decomposition path is a simple dissociation producing lithium fluoride (LiF) as solid and PF 5 as gaseous products. In the presence of water (300 ppm) in the carrier gas, its decomposition onset temperature is lowered as a result of direct thermal reaction between LiPF 6 and water vapor to form phosphorous oxyfluoride (POF 3) and hydrofluoric acid (HF). No new products were observed in 1 m solutions of LiPF 6 in ethylene carbonate (EC), dimethyl carbonate (DMC) and ethyl methyl carbonate (EMC) by on-line TGA-FTIR analysis. The storage of the same solutions in sealed containers at 85 °C for 300-420 h did not produce any significant quantity of new products as well. In particular, no alkylflurophosphates were found in the solutions after storage at elevated temperature. In the absence of either an impurity like alcohol or cathode active material that may (or may not) act as a catalyst, there is no evidence of thermally induced reaction between LiPF 6 and the prototypical Li-ion battery solvents EC, PC, DMC or EMC.

  12. Two-Step, One-Pot Synthesis of Inosine, Guanosine, and 2′-Deoxyguanosine O6-Ethers via Intermediate O6-(Benzotriazoly-1-yl) Derivatives

    PubMed Central

    Kokatla, Hari Prasad; Lakshman, Mahesh K.

    2013-01-01

    A simple method for the etherification at the O6-position of silyl-protected inosine, guanosine, and 2′-deoxyguanosine is described. Typically, a THF solution of the silylated nucleoside is treated with 1H-benzotriazol-1-yloxy-tris(dimethylamino)phosphonium hexafluorophosphate (BOP) and Cs2CO3, under a nitrogen atmosphere. Conversion to the O6-(benzotriazol-1-yl) ethers occurs within about 10 minutes for inosine, and within about 60 minutes for guanosine and 2′-deoxyguanosine. Then, for reaction with alcohols, the reaction mixture is evaporated and the O6-(benzotriazol-1-yl) ether is treated with Cs2CO3 and an appropriate alcohol, at room temperature. On the other hand, for reaction with phenols, Cs2CO3 and the appropriate phenol are added to the reaction mixture without evaporation, and the reaction is carried out at 70°C. Subsequently, workup, isolation, and purification lead to the requisite O6-alkyl or -aryl ethers in good to excellent yields. PMID:22700333

  13. Preparation and electrochemical characterization of ionic-conducting lithium lanthanum titanate oxide/polyacrylonitrile submicron composite fiber-based lithium-ion battery separators

    NASA Astrophysics Data System (ADS)

    Liang, Yinzheng; Ji, Liwen; Guo, Bingkun; Lin, Zhan; Yao, Yingfang; Li, Ying; Alcoutlabi, Mataz; Qiu, Yiping; Zhang, Xiangwu

    Lithium lanthanum titanate oxide (LLTO)/polyacrylonitrile (PAN) submicron composite fiber-based membranes were prepared by electrospinning dispersions of LLTO ceramic particles in PAN solutions. These ionic-conducting LLTO/PAN composite fiber-based membranes can be directly used as lithium-ion battery separators due to their unique porous structure. Ionic conductivities were evaluated after soaking the electrospun LLTO/PAN composite fiber-based membranes in a liquid electrolyte, 1 M lithium hexafluorophosphate (LiPF 6) in ethylene carbonate (EC)/ethyl methyl carbonate (EMC) (1:1 vol). It was found that, among membranes with various LLTO contents, 15 wt.% LLTO/PAN composite fiber-based membranes provided the highest ionic conductivity, 1.95 × 10 -3 S cm -1. Compared with pure PAN fiber membranes, LLTO/PAN composite fiber-based membranes had greater liquid electrolyte uptake, higher electrochemical stability window, and lower interfacial resistance with lithium. In addition, lithium//1 M LiPF 6/EC/EMC//lithium iron phosphate cells containing LLTO/PAN composite fiber-based membranes as the separator exhibited high discharge specific capacity of 162 mAh g -1 and good cycling performance at 0.2 C rate at room temperature.

  14. Thermal aging of electrolytes used in lithium-ion batteries - An investigation of the impact of protic impurities and different housing materials

    NASA Astrophysics Data System (ADS)

    Handel, Patricia; Fauler, Gisela; Kapper, Katja; Schmuck, Martin; Stangl, Christoph; Fischer, Roland; Uhlig, Frank; Koller, Stefan

    2014-12-01

    Thermal degradation products in lithium-ion batteries result mainly from hydrolysis sensitivity of lithium hexafluorophosphate (LiPF6). As organic carbonate solvents contain traces of protic impurities, the thermal decomposition of electrolytes is enhanced. Therefore, resulting degradation products are studied with nuclear magnetic resonance spectroscopy (NMR) and gas chromatography mass spectrometry (GC-MS). The electrolyte contains 1 M LiPF6 in a binary mixture of ethylene carbonate (EC) and diethylene carbonate (DEC) in a ratio of 1:2 (v/v) and is aged at ambient and elevated temperature. The impact of protic impurities, either added as deionized water or incorporated in positive electrode material, upon aging is investigated. Further, the influence of different housing materials on the electrolyte degradation is shown. Difluorophosphoric acid is identified as main decomposition product by NMR-spectroscopy. Traces of other decomposition products are determined by headspace GC-MS. Acid-base and coulometric titration are used to determine the total amount of acid and water content upon aging, respectively. The aim of this investigation is to achieve profound understanding about the thermal decomposition of one most common used electrolyte in a battery-like housing material.

  15. A Lithium-Ion Battery with Enhanced Safety Prepared using an Environmentally Friendly Process.

    PubMed

    Mueller, Franziska; Loeffler, Nicholas; Kim, Guk-Tae; Diemant, Thomas; Behm, R Jürgen; Passerini, Stefano

    2016-06-08

    A new lithium-ion battery chemistry is presented based on a conversion-alloying anode material, a carbon-coated Fe-doped ZnO (TMO-C), and a LiNi1/3 Mn1/3 Co1/3 O2 (NMC) cathode. Both electrodes were fabricated using an environmentally friendly cellulose-based binding agent. The performance of the new lithium-ion battery was evaluated with a conventional, carbonate-based electrolyte (ethylene carbonate:diethyl carbonate-1 m lithium hexafluorophosphate, EC:DEC 1 m LiPF6 ) and an ionic liquid (IL)-based electrolyte (N-butyl-N-methylpyrrolidinium bis(trifluoromethanesulfonyl)imide-0.2 m lithium bis(trifluoromethanesulfonyl)imide, Pyr14 TFSI 0.2 m LiTFSI), respectively. Galvanostatic charge/discharge tests revealed a reduced rate capability of the TMO-C/Pyr14 TFSI 0.2 m LiTFSI/NMC full-cell compared to the organic electrolyte, but the coulombic efficiency was significantly enhanced. Moreover, the IL-based electrolyte substantially improves the safety of the system due to a higher thermal stability of the formed anodic solid electrolyte interphase and the IL electrolyte itself. While the carbonate-based electrolyte shows sudden degradation reactions, the IL exhibits a slowly increasing heat flow, which does not constitute a serious safety risk.

  16. Quaternized polymeric microgels as metal free catalyst for H2 production from the methanolysis of sodium borohydride

    NASA Astrophysics Data System (ADS)

    Sahiner, Nurettin; Sengel, Sultan Butun

    2016-12-01

    Polymeric microgels derived from tris(2-amino ethyl)amine (TAEA) and glycerol diglycidyl ether as p(TAEA-co-GDE) via microemulsion polymerization techniques are protonated by 0.5 M HCl treatment as p(TAEA-co-GDE)-HCl). These microgels are then exposed to anion exchange reactions with differ ionic liquid forming salts, such as potassium thiocyanate (PTC), sodium dicyanamide (SDCA), ammonium hexafluorophosphate (AHFP), and sodium tetrafluoroborate (STFB) in aqueous medium for the preparation of p(TAEA-co-GDE) based ionic liquid colloidal microgels. These anions exchanged p(TAEA-co-GDE) ionic liquid colloids (ILCs) are directly used as catalyst for hydrogen (H2) generation from the methanol solution of sodium borohydride (NaBH4). Various parameters affecting the H2 production rate such as the catalyst types, NaBH4 amount, and the temperature are investigated. It is found that the methanolysis of NaBH4 catalyzed by p(TAEA-co-GDE)-HCl obeys the first order reaction kinetic. The activation energy, enthalpy and entropy of the protonated p(TAEA-co-GDE) microgels are calculated and found as the 30.37 kJ mol-1, 27.96 kJ mol-1, and -148.08 J mol-1 K-1, respectively. Furthermore, the hydrogen generation rate of 3018 mL min-1 g-1 catalyzed by p(TAEA-co-GDE)-HCl catalyst is attained.

  17. Novel synthesis of cyclic amide-linked analogues of angiotensins II and III.

    PubMed

    Matsoukas, J M; Hondrelis, J; Agelis, G; Barlos, K; Gatos, D; Ganter, R; Moore, D; Moore, G J

    1994-09-02

    Cyclic amide-linked angiotension II (ANGII) analogues have been synthesized by novel strategies, in an attempt to test the ring clustering and the charge relay bioactive conformation recently suggested. These analogues were synthesized by connecting side chain amino and carboxyl groups at positions 1 and 8, 2 and 8, 3 and 8, and 3 and 5, N-terminal amino and C-terminal carboxyl groups at positions 1 and 8, 2 and 8, and 4 and 8, and side chain amino to C-terminal carboxyl group at positions 1 and 8. All these analogues were biologically inactive, except for cyclic [Sar1, Asp3, Lys5]ANGII (analogue 10) which had high contractile activity in the rat uterus assay (30% of ANGII) and [Lys1, Tyr(Me)4, Glu8]ANGII (analogue 7) which had weak antagonist activity (PA2 approximately 6). Precyclic linear peptides synthesized using 2-chlorotrityl chloride resin and N alpha-Fmoc-amino acids with suitable side chain protection were obtained in high yield and purity and were readily cyclized with benzotriazol-1-yloxytris(dimethylamino)-phosphonium hexafluorophosphate as coupling reagent. Molecular modeling suggests that the ring structure of the potent analogue can be accommodated in the charge relay conformation proposed for ANGII.

  18. Sensitive determination of terazosin in pharmaceutical formulations and biological samples by ionic-liquid microextraction prior to spectrofluorimetry.

    PubMed

    Zeeb, Mohsen; Sadeghi, Mahdi

    2012-01-01

    An efficient and environmentally friendly sample preparation method based on the application of hydrophobic 1-Hexylpyridinium hexafluorophosphate [Hpy][PF(6)] ionic liquid (IL) as a microextraction solvent was proposed to preconcentrate terazosin. The performance of the microextraction method was improved by introducing a common ion of pyridinium IL into the sample solution. Due to the presence of the common ion, the solubility of IL significantly decreased. As a result, the phase separation successfully occurred even at high ionic strength, and the volume of the settled IL-phase was not influenced by variations in the ionic strength (up to 30% w/v). After preconcentration step, the enriched phase was introduced to the spectrofluorimeter for the determination of terazosin. The obtained results revealed that this system did not suffer from the limitations of that in conventional ionic-liquid microextraction. Under optimum experimental conditions, the proposed method provided a limit of detection (LOD) of 0.027 μg L(-1) and a relative standard deviation (R.S.D.) of 2.4%. The present method was successfully applied to terazosin determination in actual pharmaceutical formulations and biological samples. Considering the large variety of ionic liquids, the proposed microextraction method earns many merits, and will present a wide application in the future.

  19. Sensitive Determination of Terazosin in Pharmaceutical Formulations and Biological Samples by Ionic-Liquid Microextraction Prior to Spectrofluorimetry

    PubMed Central

    Zeeb, Mohsen; Sadeghi, Mahdi

    2012-01-01

    An efficient and environmentally friendly sample preparation method based on the application of hydrophobic 1-Hexylpyridinium hexafluorophosphate [Hpy][PF6] ionic liquid (IL) as a microextraction solvent was proposed to preconcentrate terazosin. The performance of the microextraction method was improved by introducing a common ion of pyridinium IL into the sample solution. Due to the presence of the common ion, the solubility of IL significantly decreased. As a result, the phase separation successfully occurred even at high ionic strength, and the volume of the settled IL-phase was not influenced by variations in the ionic strength (up to 30% w/v). After preconcentration step, the enriched phase was introduced to the spectrofluorimeter for the determination of terazosin. The obtained results revealed that this system did not suffer from the limitations of that in conventional ionic-liquid microextraction. Under optimum experimental conditions, the proposed method provided a limit of detection (LOD) of 0.027 μg L−1 and a relative standard deviation (R.S.D.) of 2.4%. The present method was successfully applied to terazosin determination in actual pharmaceutical formulations and biological samples. Considering the large variety of ionic liquids, the proposed microextraction method earns many merits, and will present a wide application in the future. PMID:22505920

  20. The effects of polymer molecular weight on the performance of single-layer polymer light emitting diodes

    NASA Astrophysics Data System (ADS)

    Mergani, Mostafa; Shahalizad, Afshin; Ahmadi Kandjani, Sohrab; Sadegh Zakerhamidi, Mohammad

    2013-11-01

    In this experimental study, poly(n-vinyl carbazole) (PVK)-based single-layer polymer light emitting diodes (PLED) were fabricated. We used PVK with 1 100 000 (PVK(h)) and 50 000 (PVK(l)) molecular weights as host polymers and 2-(4-biphenyl)-5-phenyl-1,3,4-oxadiazole (PBD) as an electron-transporting small molecule and also terabutylammonium hexafluorophosphate (TBAPF6) as an organic salt. The weight ratios of PBD and TBAPF6 were constant in all devices and the effects of PVK molecular weight on the performances of ITO/PVK(l):PBD:TBAPF6 /AL (device A), ITO/PVK(h):PBD:TBAPF6/AL (device B) and ITO/PVK(l):PVK(h):PBD:TBAPF6/AL (device C) structures were investigated. We found that the molecular weight of polymer (PVK) has considerable effects on the performances of these diodes, and consequently, their electrical and optical properties are completely dissimilar. We also observed a tendency for the formation of aggregates (in the EL) and excimers (in the PL) in the case of device (C).

  1. Biochemical responses and DNA damage in earthworms (Eisenia fetida) induced by ionic liquid [omim]PF6.

    PubMed

    Liu, Xiaoyan; Zhang, Shumin; Wang, Jinhua; Wang, Jun; Shao, Yuting; Zhu, Lusheng

    2016-04-01

    Ionic liquids that are not that "green" to many organisms have recently been identified. This study examined the subchronic toxicity of the ionic liquid 1-octyl-3-methylimidazolium hexafluorophosphate ([omim]PF6) to earthworms (Eisenia fetida). Earthworms were exposed for a 28-day period (sampled on days 7, 14, 21, and 28) at concentrations of 0, 5, 10, 20, and 40 mg/kg. The levels of reactive oxygen species (ROS), antioxidant enzymes (superoxide dismutase (SOD), catalase (CAT), guaiacol peroxidase (POD)), detoxifying enzyme (glutathione S-transferase (GST)), lipid peroxidation, and DNA damage were measured. ROS significantly accumulated in all the treatment groups; the maximum ROS content was 51.9% higher than the control at 40 mg/kg [omim]PF6 on day 28. Increased SOD activities attenuated over the time of exposure, while the CAT activities of the treatment groups were similar to the controls, except on day 14. Furthermore, the activities of POD and GST were stimulated. Lipid peroxidation in earthworms was not apparent at 5 and 10 mg/kg [omim]PF6 but was quite obvious at 40 mg/kg [omim]PF6. In addition, DNA damage was dose- and time-dependent. In conclusion, [omim]PF6 caused oxidative stress and genotoxicity in earthworms.

  2. Nitrogen, Phosphorus, and Fluorine Tri-doped Graphene as a Multifunctional Catalyst for Self-Powered Electrochemical Water Splitting.

    PubMed

    Zhang, Jintao; Dai, Liming

    2016-10-10

    Electrocatalysts are required for clean energy technologies (for example, water-splitting and metal-air batteries). The development of a multifunctional electrocatalyst composed of nitrogen, phosphorus, and fluorine tri-doped graphene is reported, which was obtained by thermal activation of a mixture of polyaniline-coated graphene oxide and ammonium hexafluorophosphate (AHF). It was found that thermal decomposition of AHF provides nitrogen, phosphorus, and fluorine sources for tri-doping with N, P, and F, and simultaneously facilitates template-free formation of porous structures as a result of thermal gas evolution. The resultant N, P, and F tri-doped graphene exhibited excellent electrocatalytic activities for the oxygen reduction reaction (ORR), oxygen evolution reaction (OER), and hydrogen evolution reaction (HER). The trifunctional metal-free catalyst was further used as an OER-HER bifunctional catalyst for oxygen and hydrogen gas production in an electrochemical water-splitting unit, which was powered by an integrated Zn-air battery based on an air electrode made from the same electrocatalyst for ORR. The integrated unit, fabricated from the newly developed N, P, and F tri-doped graphene multifunctional metal-free catalyst, can operate in ambient air with a high gas production rate of 0.496 and 0.254 μL s(-1) for hydrogen and oxygen gas, respectively, showing great potential for practical applications.

  3. Toward new organometallic architectures: synthesis of carbene-centered rhodium and palladium bisphosphine complexes. stability and reactivity of [PC(BIm)PRh(L)][PF6] pincers.

    PubMed

    Plikhta, Andriy; Pöthig, Alexander; Herdtweck, Eberhardt; Rieger, Bernhard

    2015-10-05

    In this article, we report the synthesis of a tridentate carbene-centered bisphosphine ligand precursor and its complexes. The developed four-step synthetic strategy of a new PC(BIm)P pincer ligand represents the derivatization of benzimidazole in the first and third positions by (diphenylphosphoryl)methylene synthone, followed by phosphine deprotection and subsequent insertion of a noncoordinating anion. The obtained ligand precursor undergoes complexation, with PdCl2 and [μ-OCH3Rh(COD)]2 smoothly forming the target organometallics [PC(BIm)PPdCl][PF6] and [PC(BIm)PRh(L)][PF6] under mild hydrogenation conditions. A more detailed study of the rhodium complexes [PC(BIm)PRh(L)][PF6] reveals significant thermal stability of the PC(BIm)PRh moiety in the solid state as well as in solution. The chemical behavior of 1,3-bis(diphenylphosphinomethylene)benzimidazol-2-ylrhodium acetonitrile hexafluorophosphate has been screened under decarbonylation, hydrogenation, and hydroboration reaction conditions. Thus, the PC(BIm)PRh(I) complex is a sufficiently stable compound, with the potential to be applied in catalysis.

  4. Dynamic Mass Transfer of Hemoglobin at the Aqueous/Ionic-Liquid Interface Monitored with Liquid Core Optical Waveguide.

    PubMed

    Chen, Xuwei; Yang, Xu; Zeng, Wanying; Wang, Jianhua

    2015-08-04

    Protein transfer from aqueous medium into ionic liquid is an important approach for the isolation of proteins of interest from complex biological samples. We hereby report a solid-cladding/liquid-core/liquid-cladding sandwich optical waveguide system for the purpose of monitoring the dynamic mass-transfer behaviors of hemoglobin (Hb) at the aqueous/ionic liquid interface. The optical waveguide system is fabricated by using a hydrophobic IL (1,3-dibutylimidazolium hexafluorophosphate, BBimPF6) as the core, and protein solution as one of the cladding layer. UV-vis spectra are recorded with a CCD spectrophotometer via optical fibers. The recorded spectra suggest that the mass transfer of Hb molecules between the aqueous and ionic liquid media involve accumulation of Hb on the aqueous/IL interface followed by dynamic extraction/transfer of Hb into the ionic liquid phase. A part of Hb molecules remain at the interface even after the accomplishment of the extraction/transfer process. Further investigations indicate that the mass transfer of Hb from aqueous medium into the ionic liquid phase is mainly driven by the coordination interaction between heme group of Hb and the cationic moiety of ionic liquid, for example, imidazolium cation in this particular case. In addition, hydrophobic interactions also contribute to the transfer of Hb.

  5. Microwave-assisted liquid-liquid microextraction based on solidification of ionic liquid for the determination of sulfonamides in environmental water samples.

    PubMed

    Song, Ying; Wu, Lijie; Lu, Chunmei; Li, Na; Hu, Mingzhu; Wang, Ziming

    2014-12-01

    An easy, quick, and green method, microwave-assisted liquid-liquid microextraction based on solidification of ionic liquid, was first developed and applied to the extraction of sulfonamides in environmental water samples. 1-Ethy-3-methylimidazolium hexafluorophosphate, which is a solid-state ionic liquid at room temperature, was used as extraction solvent in the present method. After microwave irradiation for 90 s, the solid-state ionic liquid was melted into liquid phase and used to finish the extraction of the analytes. The ionic liquid and sample matrix can be separated by freezing and centrifuging. Several experimental parameters, including amount of extraction solvent, microwave power and irradiation time, pH of sample solution, and ionic strength, were investigated and optimized. Under the optimum experimental conditions, good linearity was observed in the range of 2.00-400.00 μg/L with the correlation coefficients ranging from 0.9995 to 0.9999. The limits of detection for sulfathiazole, sulfachlorpyridazine, sulfamethoxazole, and sulfaphenazole were 0.39, 0.33, 0.62, and 0.85 μg/L, respectively. When the present method was applied to the analysis of environmental water samples, the recoveries of the analytes ranged from 75.09 to 115.78% and relative standard deviations were lower than 11.89%.

  6. Development of an ionic-liquid-based dispersive liquid-liquid microextraction method for the determination of antichagasic drugs in human breast milk: Optimization by central composite design.

    PubMed

    Padró, Juan M; Pellegrino Vidal, Rocío B; Echevarria, Romina N; Califano, Alicia N; Reta, Mario R

    2015-05-01

    Chagas disease constitutes a major public health problem in Latin America. Human breast milk is a biological sample of great importance for the analysis of therapeutic drugs, as unwanted exposure through breast milk could result in pharmacological effects in the nursing infant. Thus, the goal of breast milk drug analysis is to inquire to which extent a neonate may be exposed to a drug during lactation. In this work, we developed an analytical technique to quantify benznidazole and nifurtimox (the two antichagasic drugs currently available for medical treatment) in human breast milk, with a simple sample pretreatment followed by an ionic-liquid-based dispersive liquid-liquid microextraction combined with high-performance liquid chromatography and UV detection. For this technique, the ionic liquid 1-octyl-3-methylimidazolium hexafluorophosphate has been used as the "extraction solvent." A central composite design was used to find the optimum values for the significant variables affecting the extraction process: volume of ionic liquid, volume of dispersant solvent, ionic strength, and pH. At the optimum working conditions, the average recoveries were 77.5 and 89.7%, the limits of detection were 0.06 and 0.09 μg/mL and the interday reproducibilities were 6.25 and 5.77% for benznidazole and nifurtimox, respectively. The proposed methodology can be considered sensitive, simple, robust, accurate, and green.

  7. Synthesis, crystal structure, DFT studies and photophysical properties of a copper(I)-triphenylphosphane complex based on trans-(±)-2,4,5-tris(pyridin-2-yl)-2-imidazoline.

    PubMed

    Báez-Castro, Alberto; Baldenebro-López, Jesús; Ceballos-Mendivil, Laura; Román-Bravo, Perla P; Höpfl, Herbert; Miranda-Soto, Valentín; Glossman-Mitnik, Daniel; Cruz-Enríquez, Adriana; Campos-Gaxiola, José J

    2017-03-01

    The possibility of using less expensive and nontoxic metals, such as copper, as substitutes for more expensive heavy metals in the synthesis of new transition-metal complexes to be used as sensitizers in dye-sensitized solar cells (DSSCs) has stimulated research in this field. The novel photoluminescent copper(I) complex bis(triphenylphosphane-κP)[trans-(±)-2,4,5-tris(pyridin-2-yl)-2-imidazoline-κ(2)N(2),N(3)]copper(I) hexafluorophosphate, [Cu(I)(C18H15N5)(C18H15P)2]PF6, has been successfully synthesized and characterized by IR and (1)H NMR spectroscopy, as well as by single-crystal X-ray diffraction and thermogravimetric analysis. The complex showed interesting photophysical properties, which were studied experimentally in solution and in the solid state by UV-Vis and fluorescence spectroscopy. Density functional theory (DFT) calculations with dichloromethane as solvent reproduced reasonably well the HOMO and LUMO orbitals of the title compound.

  8. Effect of fractal silver electrodes on charge collection and light distribution in semiconducting organic polymer films

    SciTech Connect

    Chamousis, RL; Chang, LL; Watterson, WJ; Montgomery, RD; Taylor, RP; Moule, AJ; Shaheen, SE; Ilan, B; van de Lagemaat, J; Osterloh, FE

    2014-08-21

    Living organisms use fractal structures to optimize material and energy transport across regions of differing size scales. Here we test the effect of fractal silver electrodes on light distribution and charge collection in organic semiconducting polymer films made of P3HT and PCBM. The semiconducting polymers were deposited onto electrochemically grown fractal silver structures (5000 nm x 500 nm; fractal dimension of 1.71) with PEDOT:PSS as hole-selective interlayer. The fractal silver electrodes appear black due to increased horizontal light scattering, which is shown to improve light absorption in the polymer. According to surface photovoltage spectroscopy, fractal silver electrodes outperform the flat electrodes when the BHJ film thickness is large (>400 nm, 0.4 V photovoltage). Photocurrents of up to 200 microamperes cm(-2) are generated from the bulk heterojunction (BHJ) photoelectrodes under 435 nm LED (10-20 mW cm(-2)) illumination in acetonitrile solution containing 0.005 M ferrocenium hexafluorophosphate as the electron acceptor. The low IPCE values (0.3-0.7%) are due to slow electron transfer to ferrocenium ion and due to shunting along the large metal-polymer interface. Overall, this work provides an initial assessment of the potential of fractal electrodes for organic photovoltaic cells.

  9. The adsorption properties of Pb(II) and Cd(II) on functionalized graphene prepared by electrolysis method.

    PubMed

    Deng, Xiaojiao; Lü, Lili; Li, Hongwei; Luo, Fang

    2010-11-15

    The functionalized graphene (GNS(PF6)) was fabricated by simple and fast method of electrolysis with potassium hexafluorophosphate solution as electrolyte under the static potential of 15 V. The characterization results of transmission electron microscopy, atom force microscopy, X-ray photoelectron spectroscopy, X-ray powder diffraction, Raman spectroscopy and thermogravimetric analysis indicate that graphite rod was completely exfoliated to graphene layer containing 30 wt.% PF(6)- with the average thickness ca. 1.0 nm. Our sample of GNS(PF6) was developed for the removal of Pb(II) or Cd(II) ions from water, and the determined adsorption capacities are 406.6 mg/g (pH=5.1) for Pb(II) and 73.42 mg/g (pH=6.2) for Cd(II), which is much higher than that by our previous sample of GNS(C8P) and carbon nanotube. The adsorption processes reach equilibrium in just 40 min and the adsorption isotherms are described well by Langmuir and Freundlich classical isotherms models.

  10. Application of graphene-ionic liquid-chitosan composite-modified carbon molecular wire electrode for the sensitive determination of adenosine-5'-monophosphate.

    PubMed

    Shi, Fan; Gong, Shixing; Xu, Li; Zhu, Huanhuan; Sun, Zhenfan; Sun, Wei

    2013-12-01

    In this paper, a graphene (GR) ionic liquid (IL) 1-octyl-3-methylimidazolium hexafluorophosphate and chitosan composite-modified carbon molecular wire electrode (CMWE) was fabricated by a drop-casting method and further applied to the sensitive electrochemical detection of adenosine-5'-monophosphate (AMP). CMWE was prepared with diphenylacetylene (DPA) as the modifier and the binder. The properties of modified electrode were examined by scanning electron microscopy, cyclic voltammetry and electrochemical impedance spectroscopy. Electrochemical behaviors of AMP was carefully investigated with enhanced responses appeared, which was due to the presence of GR-IL composite on the electrode surface with excellent electrocatalytic ability. A well-defined oxidation peak of AMP appeared at 1.314 V and the electrochemical parameters were calculated by electrochemical methods. Under the selected conditions, the oxidation peak current of AMP was proportional to its concentration in the range from 0.01 μM to 80.0 μM with the detection limit as 3.42 nM (3σ) by differential pulse voltammetry. The proposed method exhibited good selectivity and was applied to the detection of vidarabine monophosphate injection samples with satisfactory results.

  11. Enhanced visible light photocatalytic degradation of Rhodamine B over phosphorus doped graphitic carbon nitride

    NASA Astrophysics Data System (ADS)

    Chai, Bo; Yan, Juntao; Wang, Chunlei; Ren, Zhandong; Zhu, Yuchan

    2017-01-01

    Phosphorus doped graphitic carbon nitride (g-C3N4) was easily synthesized using ammonium hexafluorophosphate (NH4PF6) as phosphorus source, and ammonium thiocyanate (NH4SCN) as g-C3N4 precursor, through a direct thermal co-polycondensation procedure. The obtained phosphorus doped g-C3N4 was characterized by X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), high-resolution transmission electron microscopy (HRTEM), X-ray photoelectron spectroscopy (XPS), Fourier transform infrared spectra (FTIR), UV-vis diffuse reflectance absorption spectra (UV-DRS), photoelectrochemical measurement and photoluminescence spectra (PL). The photocatalytic activities of phosphorus doped g-C3N4 samples were evaluated by degradation of Rhodamine B (RhB) solution under visible light irradiation. The results showed that the phosphorus doped g-C3N4 had a superior photocatalytic activity than that of pristine g-C3N4, attributing to the phosphorus atoms substituting carbon atoms of g-C3N4 frameworks to result in light harvesting enhancement and delocalized π-conjugated system of this copolymer, beneficial for the increase of photocatalytic performance. The photoelectrochemical measurements also verified that the charge carrier separation efficiency was promoted by phosphorus doping g-C3N4. Moreover, the tests of radical scavengers demonstrated that the holes (h+) and superoxide radicals (rad O2-) were the main active species for the degradation of RhB.

  12. All-boron fullerene exhibits a strong affinity to inorganic anions

    NASA Astrophysics Data System (ADS)

    Colherinhas, Guilherme; Fileti, Eudes Eterno; Chaban, Vitaly V.

    2017-03-01

    Experimentally observed all-boron fullerene, B-80, inspires systematic investigation of its physical chemical properties and search for possible applications. We hereby report density functional theory calculations to characterize interactions of B-80 with the selected imidazolium room-temperature ionic liquids (RTILs), dimethylimidazolium nitrate and dimethylimidazolium hexafluorophosphate. Whereas the imidazolium cation exhibits a rather poor affinity to B-80, the inorganic anions form polar covalent bonds with the boron atom occupying a central position within a B-6 hexagon. Attachment of the RTIL ion pairs leads to a significant alteration of the electronic spectra, charge density distribution, valence and conduction molecular orbitals. The total binding energies keeping the RTIL@B80 complexes together range 200-250 kcal mol-1, being higher than the energies of many interactions in chemistry. The observed phenomenon predicts an excellent solubility of B-80 in the considered RTILs, but may also reveal a poor stability of B-80 in the polar media. Our results motivate further efforts in studying the behavior of the all-boron fullerene in polar environments.

  13. A nonaqueous lyotropic liquid crystal fabricated by a polyoxyethylene amphiphile in protic ionic liquid.

    PubMed

    Ma, Fumin; Chen, Xiao; Zhao, Yurong; Wang, Xudong; Li, Qiuhong; Lv, Chao; Yue, Xiu

    2010-06-01

    The aggregation behaviors of oleyl polyoxyethylene (10) ether, Brij 97, in room temperature ionic liquids, ethylammonium nitrate (EAN), pyrrolidinium nitrate ([Pyrr][NO(3)]), ethylammonium butyrate (EAB), 1-butyl-3-methylimidazolium hexafluorophosphate ([Bmim][PF(6)]), and 1-butyl-3-methylimidazolium tetrafluoroborate ([Bmim][BF(4)]), have been investigated. Only in the Brij 97/EAN binary system is the hexagonal liquid crystalline phase formed, and its ordering is found to decrease with increasing temperature. The lattice spacing values measured from the small-angle X-ray scattering (SAXS) shrink with reduction of ionic liquid content at room temperature. The general rules for aggregate formation in these ionic liquids are discussed and compared with that in water. A degraded ability to produce the ordered self-assembly of Brij 97 from H(2)O to EAN to [Bmim][PF(6)], [Bmim][BF(4)], [Pyrr][NO(3)], and EAB is found and analyzed based on the molecular packing and Gordon parameters and also hydrogen-bonding or solvophobic interactions. Steady-shear rheological measurements combined with the frequency sweep data indicate the highly viscoelastic nature of this liquid crystalline phase.

  14. Influence of the organized structure of 1-alkyl-3-methylimidazolium-based ionic liquids on the rotational diffusion of an ionic solute.

    PubMed

    Gangamallaiah, V; Dutt, G B

    2013-08-29

    To understand the influence of organized structure of the ionic liquids on the rotational diffusion of a hydrogen bond donating ionic solute, reorientation times (τr) of rhodamine 110 (R110) have been measured in 1-alkyl-3-methylimidazolium ([Rmim+]) based ionic liquids with anions tetrafluoroborate ([BF4-]) and hexafluorophosphate ([PF6-]). The viscosity (η) was varied by changing the temperature (T) and also the alkyl chain length on the imidazolium cation (ethyl, butyl, hexyl, and octyl). It has been noticed that τr versus η/T plots contain two slopes corresponding to lower and higher values of η/T for ionic liquids with [BF4-] as well as [PF6-] anions. For lower values of η/T (<0.2 and <0.3 mPa s K(-1), respectively, for [Rmim+][BF4-] and [Rmim+][PF6-]), rotational diffusion of R110 follows Stokes-Einstein-Debye hydrodynamic theory with stick boundary condition due to specific interactions between the solute and the anions of the ionic liquids. In contrast, at higher η/T, the rotational diffusion of the solute is faster than the stick predictions and this trend could not be explained by the quasihydrodynamic theories of Gierer-Wirtz and Dote-Kivelson-Schwartz as well. Diminishing hydrogen bonding interactions between the solute and the anions, which transpire as a consequence of the organized structure of the ionic liquids, are responsible for the observed behavior.

  15. Photoinduced electron transfer between 2-methylanthraquinone and triethylamine in an ionic liquid: Time-resolved EPR and transient absorption spectroscopy study

    NASA Astrophysics Data System (ADS)

    Zhu, Guanglai; Wang, Yu; Fu, Haiying; Xu, Xinsheng; Cui, Zhifeng; Ji, Xuehan; Wu, Guozhong

    2015-02-01

    Photoinduced electron transfer between 2-methylanthraquinone (MeAQ) and triethylamine (TEA) in a room-temperature ionic liquid, 1-butyl-3-methylimidazolium hexafluorophosphate ([bmim][PF6]), was investigated by comparing the time-resolved electron paramagnetic resonance (TR-EPR) spectroscopy and the transient absorption spectroscopy. The results of TR-EPR spectroscopy, in which MeAQ was 8 mmol L-1 and TEA was 150 mmol L-1, indicated that the transient radical would exist longer time in [bmim][PF6] than in acetonitrile. At the delay time of 8 μs after laser excitation, the TR-EPR signal transformed from an emissive peak into an absorptive peak when the experiment was performed in [bmim][PF6]. The results of the transient absorption spectroscopy, in which MeAQ was 0.1 mmol L-1 and TEA was 2.2 mmol L-1, showed that the efficiency and the rate of the photoinduced electron transfer reaction in [bmim][PF6] were obviously lower than that in acetonitrile. It was concluded that various factors, such as concentration, viscosity and local structural transformation of the solution, have an influence on the process of photoinduced electron transfer in [bmim][PF6].

  16. Simultaneous electrochemical sensing of thallium, lead and mercury using a novel ionic liquid/graphene modified electrode.

    PubMed

    Bagheri, Hasan; Afkhami, Abbas; Khoshsafar, Hosein; Rezaei, Mosayeb; Sabounchei, Seyed Javad; Sarlakifar, Mehdi

    2015-04-22

    In the present manuscript, an electrochemical sensor for the sensitive detection of Tl(+), Pb(2+) and Hg(2+) is described. A new composite electrode has been fabricated using graphene, 1-n-octylpyridinum hexafluorophosphate (OPFP), and [2,4-Cl2C6H3C(O)CHPPh3] (L), as a new synthetic phosphorus ylide. The physicochemical and electrochemical characterizations of fabricated sensor were investigated in details. The advantages of the proposed composite electrode are its ability in simultaneous electrochemical detection of Tl(+), Pb(2+) and Hg(2+) with good selectivity, stability and no need for separating of the three species from complex mixtures prior to electrochemical measurements. The analytical performance of the proposed electrode was examined using square wave voltammetry. Tl(+), Pb(2+) and Hg(2+) can be determined in linear ranges from 1.25×10(-9) to 2.00×10(-7) mol L(-1). Low detection limits of 3.57×10(-10) mol L(-1) for Tl(+), 4.50×10(-10) mol L(-1) for Pb(2+) and 3.86×10(-10) mol L(-1) for Hg(2+) were achieved. Finally, the proposed electrochemical sensor was applied to detect trace analyte ions in various water and soil samples with satisfactory results.

  17. Highly luminescent yellow and yellowish-green light-emitting electrochemical cells based on cationic iridium complexes with phenanthroline based ancillary ligands

    NASA Astrophysics Data System (ADS)

    Sunesh, Chozhidakath Damodharan; Chandran, Midhun; Mathai, George; Choe, Youngson

    2013-01-01

    Highly luminescent light-emitting electrochemical cells (LECs) based on cationic iridium complexes [Ir(ppz)2(dpphen)]PF6 (1) and [Ir(ppz)2(tmphen)]PF6 (2) (ppz is 1-phenylpyrazole, dpphen is 4,7-diphenyl-1,10-phenanthroline and tmphen is 3,4,7,8-tetramethyl-1,10-phenanthroline) with phenanthroline based ancillary ligands were fabricated using air stable electrodes and their electroluminescent properties were investigated. LECs based on complex 1 emitted yellow electroluminescence (λmax 574 nm) with Commission Internationale de L'Eclairage (CIE) coordinates of (0.49, 0.50) while the complex 2 gave yellowish-green electroluminescence (λmax 537 nm) with CIE coordinates of (0.35, 0.58). The work done here reveals that the alkyl substituted phenanthroline ancillary ligand, tmphen shifts the light emission to the shorter wavelength region than the phenyl substituted dpphen ligand, resulting in the color tuning of the light-emitting devices. Density functional theory (DFT) calculations were performed to gain insight into the molecular surfaces of cationic iridium complexes and their electrochemical behaviors. Single layer LECs based on these complexes exhibited a high luminescence of 5199 and 4751 cd/m2 for complexes 1 and 2 respectively. The ionic liquid, 1-ethyl-3-methylimidazolium hexafluorophosphate (EMIMPF6) was added to the light emitting layer and hence higher luminances were obtained than the pristine device.

  18. Stereochemical consequences of oxygen atom transfer and electron transfer in imido/oxido molybdenum(IV, V, VI) complexes with two unsymmetric bidentate ligands.

    PubMed

    Hüttinger, Kristina; Förster, Christoph; Bund, Timo; Hinderberger, Dariush; Heinze, Katja

    2012-04-02

    Two equivalents of the unsymmetrical Schiff base ligand (L(tBu))(-) (4-tert-butyl phenyl(pyrrolato-2-ylmethylene)amine) and MoCl(2)(NtBu)O(dme) (dme = 1,2-dimethoxyethane) gave a single stereoisomer of a mixed imido/oxido Mo(VI) complex 2(tBu). The stereochemistry of 2(tBu) was elucidated using X-ray diffraction, NMR spectroscopy, and DFT calculations. The complex is active in an oxygen atom transfer (OAT) reaction to trimethyl phosphane. The putative intermediate five-coordinate Mo(IV) imido complex coordinates a PMe(3) ligand, giving the six-coordinate imido phosphane Mo(IV) complex 5(tBu). The stereochemistry of 5(tBu) is different from that of 2(tBu) as shown by NMR spectroscopy, DFT calculations, and X-ray diffraction. Single-electron oxidation of 5(tBu) with ferrocenium hexafluorophosphate gave the stable cationic imido phosphane Mo(V) complex [5(tBu)](+) as the PF(6)(-) salt. EPR spectra of [5(tBu)](PF(6)) confirmed the presence of PMe(3) in the coordination sphere. Single-crystal X-ray diffraction analysis of [5(tBu)](PF(6)) revealed that electron transfer occurred under retention of the stereochemical configuration. The rate of OAT, the outcome of the electron transfer reaction, and the stabilities of the imido complexes presented here differ dramatically from those of analogous oxido complexes.

  19. Cladribine Analogues via O⁶-(Benzotriazolyl) Derivatives of Guanine Nucleosides.

    PubMed

    Satishkumar, Sakilam; Vuram, Prasanna K; Relangi, Siva Subrahmanyam; Gurram, Venkateshwarlu; Zhou, Hong; Kreitman, Robert J; Montemayor, Michelle M Martínez; Yang, Lijia; Kaliyaperumal, Muralidharan; Sharma, Somesh; Pottabathini, Narender; Lakshman, Mahesh K

    2015-10-09

    Cladribine, 2-chloro-2'-deoxyadenosine, is a highly efficacious, clinically used nucleoside for the treatment of hairy cell leukemia. It is also being evaluated against other lymphoid malignancies and has been a molecule of interest for well over half a century. In continuation of our interest in the amide bond-activation in purine nucleosides via the use of (benzotriazol-1yl-oxy)tris(dimethylamino)phosphonium hexafluorophosphate, we have evaluated the use of O⁶-(benzotriazol-1-yl)-2'-deoxyguanosine as a potential precursor to cladribine and its analogues. These compounds, after appropriate deprotection, were assessed for their biological activities, and the data are presented herein. Against hairy cell leukemia (HCL), T-cell lymphoma (TCL) and chronic lymphocytic leukemia (CLL), cladribine was the most active against all. The bromo analogue of cladribine showed comparable activity to the ribose analogue of cladribine against HCL, but was more active against TCL and CLL. The bromo ribose analogue of cladribine showed activity, but was the least active among the C6-NH₂-containing compounds. Substitution with alkyl groups at the exocyclic amino group appears detrimental to activity, and only the C6 piperidinyl cladribine analogue demonstrated any activity. Against adenocarcinoma MDA-MB-231 cells, cladribine and its ribose analogue were most active.

  20. Electrochemical Performance of LiNi0.5Mn1.5O4 by Sol-gel Self-combustion Reaction Method in Different Kinds of Electrolyte for High-voltage Rechargeable Lithium Cells

    NASA Astrophysics Data System (ADS)

    Liang, Xinghua; Shi, Lin; Liu, Yusi; Zeng, Shuaibo; Ye, Chaochao

    2015-07-01

    LiNi0.5Mn1.5O4 cathode material was synthesized through sol-gel self-combustion reaction method. LiNi0.5Mn1.5O4 powders were subsequently characterized as cathode materials in a Li-ion coin cell comprising a Li anode with electrolyte A or electrolyte B. 1.0 mol/L Lithium Hexafluorophosphate (LiPF6) dissolved in volume ration of ethylene carbonate (EC) to ethyl methyl carbonate (EMC) to diethyl carbonate (DEC) corresponded to 4:3:3as electrolyte A, 1.0 mol/L LiPF6 dissolved in volume ration of EC to EMC to DEC corresponded to 4:2:4 as electrolyte B. Electrochemical performance of lithium cells was evaluated. These tests showed that no matter the cells with electrolyte A or electrolyte B has good discharge platform in 4.7V range (3.5V-4.75V) at the rate of 0.1C, the initial discharge capacity of cell with electrolyte B was higher than that with electrolyte A.

  1. Enzymatic Transesterification of Kraft Lignin with Long Acyl Chains in Ionic Liquids.

    PubMed

    Hulin, Lise; Husson, Eric; Bonnet, Jean-Pierre; Stevanovic, Tatjana; Sarazin, Catherine

    2015-09-09

    Valorization of lignin is essential for the economic viability of the biorefinery concept. For example, the enhancement of lignin hydrophobicity by chemical esterification is known to improve its miscibility in apolar polyolefin matrices, thereby helping the production of bio-based composites. To this end and due to its many reactive hydroxyl groups, lignin is a challenging macromolecular substrate for biocatalyzed esterification in non-conventional media. The present work describes for the first time the lipase-catalyzed transesterification of Kraft lignin in ionic liquids (ILs). Three lipases, three 1-butyl-3-methylimidazolium based ILs and ethyl oleate as long chain acyl donor were selected. Best results were obtained with a hydrophilic/hydrophobic binary IL system (1-butyl-3-methylimidazolium trifluoromethanesulfonate/1-butyl-3-methylimidazolium hexafluoro- phosphate, 1/1 v/v) and the immobilized lipase B from Candida antarctica (CALB) that afforded a promising transesterification yield (ca. 30%). Similar performances were achieved by using 1-butyl-3-methylimidazolium hexafluorophosphate as a coating agent for CALB rather than as a co-solvent in 1-butyl-3-methylimidazolium trifluoromethane-sulfonate thus limiting the use of hydrophobic IL. Structural characterization of lignin oleate was performed by spectroscopic studies (FTIR and ¹H-NMR). The synthesized lignin oleate exhibited interesting thermal and textural properties, different from those of the original Kraft lignin.

  2. What determines the rate of excited-state intramolecular electron-transfer reaction of 4-(N,N'-dimethylamino)benzonitrile in room temperature ionic liquids? A study in [bmim][PF6].

    PubMed

    Santhosh, Kotni; Samanta, Anunay

    2012-05-14

    The kinetics of excited-state intramolecular electron-transfer reaction and dynamics of solvation of the intramolecular charge transfer (ICT) state of 4-(N,N'-dimethylamino)benzonitrile (DMABN) was studied in 1-butyl-3-methylimidazloium hexafluorophosphate, [bmim][PF(6)], by monitoring the dual fluorescence of the system. The picosecond time-resolved emission spectra (TRES) of DMABN exhibit decay of the locally excited (LE) emission intensity and shift of the ICT emission peak position with time, thus capturing the kinetics of evolution of the ICT state from the LE state and solvent relaxation of the ICT state. These results show that the LE→ICT transformation rate is determined not by the slow dynamics of solvation in ionic liquid, but is controlled mainly by the rate of structural reorganization of the molecule, which accompanies the electron-transfer process in this polar viscous medium. Even though both solvent reorganization around photo-excited DMABN and structural rearrangement of the molecule are dependent on the viscosity of the medium, it is the latter process that contributes to the viscosity dependence of the LE→ICT transformation.

  3. Inkjet printing of nanoporous gold electrode arrays on cellulose membranes for high-sensitive paper-like electrochemical oxygen sensors using ionic liquid electrolytes.

    PubMed

    Hu, Chengguo; Bai, Xiaoyun; Wang, Yingkai; Jin, Wei; Zhang, Xuan; Hu, Shengshui

    2012-04-17

    A simple approach to the mass production of nanoporous gold electrode arrays on cellulose membranes for electrochemical sensing of oxygen using ionic liquid (IL) electrolytes was established. The approach, combining the inkjet printing of gold nanoparticle (GNP) patterns with the self-catalytic growth of these patterns into conducting layers, can fabricate hundreds of self-designed gold arrays on cellulose membranes within several hours using an inexpensive inkjet printer. The resulting paper-based gold electrode arrays (PGEAs) had several unique properties as thin-film sensor platforms, including good conductivity, excellent flexibility, high integration, and low cost. The porous nature of PGEAs also allowed the addition of electrolytes from the back cellulose membrane side and controllably produced large three-phase electrolyte/electrode/gas interfaces at the front electrode side. A novel paper-based solid-state electrochemical oxygen (O(2)) sensor was therefore developed using an IL electrolyte, 1-butyl-3-methylimidazolium hexafluorophosphate (BMIMPF(6)). The sensor looked like a piece of paper but possessed high sensitivity for O(2) in a linear range from 0.054 to 0.177 v/v %, along with a low detection limit of 0.0075% and a short response time of less than 10 s, foreseeing its promising applications in developing cost-effective and environment-friendly paper-based electrochemical gas sensors.

  4. Influence of the counter ion on the structure of two new copper(I) coordination polymers: Synthesis, structural characterization and thermal analysis

    NASA Astrophysics Data System (ADS)

    Beheshti, Azizolla; Nobakht, Valiollah; Carlucci, Lucia; Proserpio, Davide M.; Abrahams, Carmel

    2013-04-01

    Two new coordination polymers [Cu2(μ3-SCN)2(μ-bbd)]n (1) and {[Cu(μ-bbd)1.5](PF6)}n (2) were synthesized by the reactions of 1,4-bis(3,5-dimethylpyrazol-1-yl)butane (bbd) with the corresponding copper(I) salts, in order to evaluate the effect of the counter anion on the structure of the resulting products. The structure of these compounds were determined by X-ray crystallography; Compound 1 is a 2D coordination polymer, in which the thiocyanate ligand adopts uncommon μ3-1κ1N;2:3κ2S coordination mode to link three tetrahedrally coordinated copper centers. The fourth coordination site on each copper atom is occupied by a pyrazole nitrogen atom belonging to a μ-bbd ligand. In contrast to 1, 2 is a 1D chain coordination polymer in which the copper atoms, adopting a distorted trigonal planar geometry, are linked by bridging bbd ligands having alternately two different conformations. The results indicate that the use of a coordinating counter anion as thiocyanate which is capable of bridging more than one metal center instead of non-coordinating hexafluorophosphate anion, promotes the formation of a 2D polymer over a 1D polymeric chain. The complexes have also been characterized by elemental analysis, IR spectroscopy, XRPD and thermal analysis.

  5. Halloysite clay nanotubes and platinum nanoparticles dispersed in ionic liquid applied in the development of a catecholamine biosensor.

    PubMed

    Brondani, Daniela; Scheeren, Carla Weber; Dupont, Jairton; Vieira, Iolanda Cruz

    2012-08-21

    Halloysite clay nanotubes were used as a support for the immobilization of the enzyme peroxidase from clover sprouts (Trifolium), and employed together with platinum nanoparticles in 1-butyl-3-methylimidazolium hexafluorophosphate ionic liquid (Pt-BMI·PF(6)) in the development of a new biosensor for the determination of catecholamines by square-wave voltammetry. Under optimized conditions, the analytical curves showed detection limits of 0.05, 0.06, 0.07, 0.12 μM for dopamine, isoproterenol, dobutamine and epinephrine, respectively. The biosensor demonstrated high sensitivity, good repeatability and reproducibility, and long-term stability (18% decrease in response over 150 days). A recovery study of dopamine in pharmaceutical samples gave values from 97.5 to 101.4%. The proposed biosensor was successfully applied to the determination of dopamine in pharmaceutical samples, with a maximum relative error of ±1.0% in relation to the standard (spectrophotometric) method. The good analytical performance of the proposed method can be attributed to the efficient immobilization of the peroxidase in the nanoclay, and the facilitation of electron transfer between the protein and the electrode surface due to the presence of the Pt nanoparticles and ionic liquid.

  6. Development of an Analytical Method Based on Temperature Controlled Solid-Liquid Extraction Using an Ionic Liquid as Solid Solvent.

    PubMed

    Pan, Zhongwei; Wang, Zhengquan; Zhu, Linna; Zhu, Zhiming; Cai, Jinying; Shen, Xiaoman; Fan, Tingli; Zhang, Yingnan; Chen, Zhixiu

    2015-12-10

    At the present paper, an analytical method based on temperature controlled solid-liquid extraction (TC-SLE) utilizing a synthesized ionic liquid, (N-butylpyridinium hexafluorophosphate, [BPy]PF₆), as solid solvent and phenanthroline (PT) as an extractant was developed to determine micro levels of Fe(2+) in tea by PT spectrophotometry. TC-SLE was carried out in two continuous steps: Fe(2+) can be completely extracted by PT-[BPy]PF₆ or back-extracted at 80 °C and the two phases were separated automatically by cooling to room temperature. Fe(2+), after back-extraction, needs 2 mol/L HNO₃ as stripping agent and the whole process was determined by PT spectrophotometry at room temperature. The extracted species was neutral Fe(PT)mCl₂ (m = 1) according to slope analysis in the Fe(2+)-[BPy]PF₆-PT TC-SLE system. The calibration curve was Y = 0.20856X - 0.000775 (correlation coefficient = 0.99991). The linear calibration range was 0.10-4.50 μg/mL and the limit of detection for Fe(2+) is 7.0 × 10(-2) μg/mL. In this method, the contents of Fe(2+) in Tieguanyin tea were determined with RSDs (n = 5) 3.05% and recoveries in range of 90.6%-108.6%.

  7. Temperature Dependent Low Frequency Optical and DC Transport Near a Metal Insulator Transition

    NASA Astrophysics Data System (ADS)

    Kohlman, R. S.; Epstein, A. J.; Tanner, D. B.; Ihas, G. G.; Ishiguro, T.; Kaneko, H.; Min, Y. G.; MacDiarmid, A. G.

    1996-03-01

    We report measurements of the temperature dependent far infrared (10-100 cm-1) reflectance and milliKelvin transport of highly conducting polyaniline doped with d,1-camphorsulfonic acid (PAN-CSA) and polypyrrole doped with hexafluorophosphate (PPy-PF_6). With decreasing T (to ~ 200 K), the reflectance initially increases for ω > 20 cm-1 and decreases at lower frequencies. As T is further decreased, there is a continuous reduction in the reflection. There is no indication of a gap opening at low temperatures in contrast to earlier reports for PPy-PF_6.^1 These results will be discussed along with mK magnetotransport measurements for ``metallic'' PAN-CSA samples that have a negative magnetoresistance similar to metallic PPy-PF6 ^2 and other nonmetallic samples, indicating the importance of weak localization channels for transport in highly conducting polymers. ^*Supported in part by NIST ATP 1993-01-0149 and NSF DMR-9403894. ^1K. Lee, et al., Synth. Met. 68, 287 (1995). ^2J. C. Clark, et al., Synth. Met. 69, 215 (1995).

  8. Facile synthesis and color-tunable properties of BaLuF5:Ce,Tb,Eu(Sm) submicrospheres via a facile ionic liquid/EG two-phase system.

    PubMed

    Song, Yanhua; Li, Yi; Zhao, Tianqi; Wang, Yuexin; Cui, Tingting; Sheng, Ye; Zheng, Keyan; Zhou, Xiuqing; You, Hongpeng; Zou, Haifeng

    2017-02-01

    BaLuF5:Ce,Tb,Eu(Sm) submicrospheres were synthesized via an ILs/ethylene glycol(EG) two-phase system. The crystalline phase, size, morphology, and luminescence properties were characterized using powder X-ray diffraction (XRD), field emission-scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), photoluminescence (PL) spectra. The results show that 1-methyl-3-octylimidazolium hexafluorophosphate ([Omim]PF6) was used as fluoride source and capping agent to tune morphology and size of the crystals. The formation mechanism has been supposed. Under the excitation of ultraviolet, the BaLuF5:5%Ce(3+),5%Tb(3+), BaLuF5:Eu(3+), and BaLuF5:5%Ce(3+),5%Sm(3+) exhibit green and red emission, which was derived from Tb(3+), Eu(3+), and Sm(3+) emission. When codoping Ce(3+), Tb(3+), Sm(3+) or Eu(3+) together, multi-color emission can be realized. Furthermore, this synthetic route may have potential applications for fabricating other lanthanide fluorides.

  9. Structure and mechanisms underlying ion transport in ternary polymer electrolytes containing ionic liquids

    NASA Astrophysics Data System (ADS)

    Mogurampelly, Santosh; Ganesan, Venkat

    2017-02-01

    We use all atom molecular dynamics simulations to investigate the influence of 1-butyl-3-methylimidazolium hexafluorophosphate (BMIMPF6) ionic liquid on the structure and transport properties of poly(ethylene oxide) (PEO) polymer electrolytes doped with LiPF6 salt. We observe enhanced diffusivities of the Li+, PF6-, and BMIM+ ions with increasing loading of the ionic liquid. Interplay between the different ion-ion and ion-polymer interactions is seen to lead to a destabilization of the Li-PF6 coordination and increase in the strength of association between the Li+ cations and the polymer backbone. As a consequence, the polymer segmental relaxation times are shown to be only moderately affected by the addition of ionic liquids. The ionic-liquid induced changes in the mobilities of Li+ ions are seen to be correlated to polymer segmental relaxation times. However, the mobilities of BMIM+ ions are seen to be more strongly correlated to the BMIM-PF6 ion-pair relaxation times.

  10. Halogen-free bis(imidazolium)/bis(ammonium)-di[bis(salicylato)borate] ionic liquids as energy-efficient and environmentally friendly lubricant additives.

    PubMed

    Gusain, Rashi; Gupta, Piyush; Saran, Sandeep; Khatri, Om P

    2014-09-10

    Bis(imidazolium)- and bis(ammonium)-di[bis(salicylato)borate] ionic liquids with variable alkyl chain and cyclic ring structures, were synthesized and then evaluated them as potential lubricant additives. The copper strip test results revealed noncorrosive properties of these ionic liquids. Introduction of halogen content in bis(imidazolium) ionic liquid by replacement of bis(salicylato)borate (BScB) anion with hexafluorophosphate (PF6(-)), severely corroded the copper strip. Thermogravimetric results showed that bis(imidazolium) ionic liquids exhibited higher thermal stability than bis(ammonium) ionic liquids owing to compact structure provided by imidazolium rings, higher intermolecular interactions, smaller free volume and low steric hindrance. The lubrication properties of these ionic liquids as additives to synthetic lubricant poly(ethylene) glycol (PEG 200) were evaluated for steel balls. Results showed that bis(ammonium)- and bis(imidazolium)-(BScB)2 ionic liquids as additives significantly reduced both friction coefficient and wear of PEG 200. The structure of cations, particularly the variation in substituted alkyl chain length monitored the degree of reduction in friction and wear. The excellent lubrication properties were attributed to the formation of adsorbed tribo-thin film and tribochemical product during the tribo-contact. Being halogen-, phosphorus-, and sulfur-free, these ionic liquids (a) protects contact surfaces from tribo-corrosive events, (b) reduces the friction and wear, and (c) keep environment green and clean.

  11. Extraction of ranitidine and nizatidine with using imidazolium ionic liquids prior spectrophotometric and chromatographic detection.

    PubMed

    Kiszkiel, Ilona; Starczewska, Barbara; Leśniewska, Barbara; Późniak, Patrycja

    2015-03-15

    A new extraction medium was proposed for liquid-liquid extraction of the histamine H2 receptor antagonists ranitidine (RNT) and nizatidine (NZT). The ionic liquids with low vapor pressure and favorable solvating properties for a range of compounds such as 1-butyl-3-methylimidazolium hexafluorophosphate [C4mim][PF6] and 1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide [C4mim][Tf2N] were tested for isolation of analytes. The extraction parameters of RNT and NZT, namely, amount of ionic liquid, pH of sample solution, shaking and centrifugation time were optimized. The isolation processes were performed with 1 mL of the ionic liquids. The extracted samples (pH values near 4) were shaken at 1750 rpm. The influence of interfering substances on the efficiency of extraction process was also studied. Methods for the histamine H2 receptor antagonists (ranitidine and nizatidine) determination after their separation using imidazolium ionic liquids by high performance liquid chromatography (HPLC) combined with UV spectrophotometry were developed. The application of ionic liquids in extraction step allows for selective isolation of analytes from aqueous matrices and their preconcentration. The above methods were applied to the determination of RNT and NZT in environmental samples (river water and wastewater after treatment).

  12. Ionic liquids monolithic columns for protein separation in capillary electrochromatography.

    PubMed

    Liu, Cui-Cui; Deng, Qi-Liang; Fang, Guo-Zhen; Liu, Hui-Lin; Wu, Jian-Hua; Pan, Ming-Fei; Wang, Shuo

    2013-12-04

    A series of ionic liquids (ILs) monolithic capillary columns based on 1-vinyl-3-octylimidazolium (ViOcIm(+)) were prepared by two approaches ("one-pot" approach and "anion-exchange" approach). The effects of different anions (bromide, Br(-); tetrafluoroborate, BF4(-); hexafluorophosphate, PF6(-); and bis-trifluoromethanesulfonylimide, NTf2(-)) on chromatography performance of all the resulting columns were investigated systematically under capillary electrochromatography (CEC) mode. The results indicated that all these columns could generate a stable reversed electroosmotic flow (EOF) over a wide pH range from 2.0 to 12.0. For the columns prepared by "one-pot" approach, the EOF decreased in the order of ViOcIm(+)Br(-)>ViOcIm(+)BF4(-)>ViOcIm(+)PF6(-)>ViOcIm(+)NTf2(-) under the same CEC conditions; the ViOcIm(+)Br(-) based column exhibited highest column efficiencies for the test small molecules; the ViOcIm(+)NTf2(-) based column possessed the strongest retention for aromatic hydrocarbons; and baseline separation of four standard proteins was achieved on ViOcIm(+)NTf2(-) based column corresponding to the highest column efficiency of 479,000 N m(-1) for cytochrome c (Cyt c). These results indicated that the property of ILs based columns could be tuned successfully by changing anions, which gave these columns potential to separate both small molecules and macro biomolecules.

  13. Development of an ionic liquid based dispersive liquid-liquid microextraction method for the analysis of polycyclic aromatic hydrocarbons in water samples.

    PubMed

    Pena, M Teresa; Casais, M Carmen; Mejuto, M Carmen; Cela, Rafael

    2009-09-04

    A simple, rapid and efficient method, ionic liquid based dispersive liquid-liquid microextraction (IL-DLLME), has been developed for the first time for the determination of 18 polycyclic aromatic hydrocarbons (PAHs) in water samples. The chemical affinity between the ionic liquid (1-octyl-3-methylimidazolium hexafluorophosphate) and the analytes permits the extraction of the PAHs from the sample matrix also allowing their preconcentration. Thus, this technique combines extraction and concentration of the analytes into one step and avoids using toxic chlorinated solvents. The factors affecting the extraction efficiency, such as the type and volume of ionic liquid, type and volume of disperser solvent, extraction time, dispersion stage, centrifuging time and ionic strength, were optimised. Analysis of extracts was performed by high performance liquid chromatography (HPLC) coupled with fluorescence detection (Flu). The optimised method exhibited a good precision level with relative standard deviation values between 1.2% and 5.7%. Quantification limits obtained for all of these considered compounds (between 0.1 and 7 ng L(-1)) were well below the limits recommended in the EU. The extraction yields for the different compounds obtained by IL-DLLME, ranged from 90.3% to 103.8%. Furthermore, high enrichment factors (301-346) were also achieved. The extraction efficiency of the optimised method is compared with that achieved by liquid-liquid extraction. Finally, the proposed method was successfully applied to the analysis of PAHs in real water samples (tap, bottled, fountain, well, river, rainwater, treated and raw wastewater).

  14. Arsenic speciation analysis in mono-varietal wines by on-line ionic liquid-based dispersive liquid-liquid microextraction.

    PubMed

    Escudero, Leticia B; Martinis, Estefanía M; Olsina, Roberto A; Wuilloud, Rodolfo G

    2013-05-01

    A highly efficient separation and pre-concentration method for arsenic species determination, based on ionic liquid (IL) dispersive microextraction technique implemented in a flow analysis system, is proposed. Highly selective separation of arsenite species [As(III)] was achieved by chelation with sodium diethyldithiocarbamate (DDTC) followed by dispersion with 40 mg of 1-octyl-3-methylimidazolium hexafluorophosphate ([C(8)mim][PF(6)]) IL. Analyte extraction, retention and separation of IL phase were achieved with a packed microcolumn and As(III) was determined in eluent solution by electrothermal atomic absorption spectrometry (ETAAS). Concentration of As(V) was deduced by the difference between total inorganic arsenic and As(III). Thus, determination of total arsenic was performed by previous degradation of organo-arsenic species, followed by a reduction. Under optimal conditions, As(III) extraction efficiency was 100% and a sensitivity enhancement factor of 46 was obtained with only 4.0 ml of sample The method was successfully applied for arsenic speciation studies in mono-varietal wines.

  15. Determination of pyrethroid pesticides in tomato using ionic liquid-based dispersive liquid-liquid microextraction.

    PubMed

    Han, Dandan; Tang, Baokun; Row, Kyung Ho

    2014-03-01

    A sensitive determination method was developed for the analysis of pyrethroid pesticide residues in tomato samples using ionic liquid-based dispersive liquid-liquid microextraction. A hydrophobic ionic liquid (1-butyl-3-methylimidazolium hexafluorophosphate) and acetonitrile were used as the extraction solvent and dispersive solvent, respectively. The following experimental parameters affecting the extraction efficiency were examined: types of extraction solvent and volume of extraction solvent, types of dispersive solvent and volume of dispersive solvent and pH and ion strength of the sample solution. Under the optimum conditions, the extraction recoveries ranged from 83.9 to 96.7%. Moreover, the enrichment factors for esbiothrin, fenpropathrin and cyhalothrin were 42, 48 and 45, respectively. The calibration curves were linear with correlation coefficients ranging from 0.9997 to 0.9999 at concentrations of 0.05-1.5 µg/kg. The relative standard deviation (n = 5) was 1.7-4.5%. The limits of detection for esbiothrin, fenpropathrin and cyhalothrin were 8.1, 9.9 and 14.3 µg/kg, respectively.

  16. Temperature-controlled ionic liquid-based ultrasound-assisted microextraction for preconcentration of trace quantity of cadmium and nickel by using organic ligand in artificial saliva extract of smokeless tobacco products.

    PubMed

    Arain, Sadaf Sadia; Kazi, Tasneem Gul; Arain, Asma Jabeen; Afridi, Hassan Imran; Baig, Jameel Ahmed; Brahman, Kapil Dev; Naeemullah; Arain, Salma Aslam

    2015-03-05

    A new approach was developed for the preconcentration of cadmium (Cd) and nickel (Ni) in artificial saliva extract of dry snuff (brown and black) products using temperature-controlled ionic liquid-based ultrasound-assisted dispersive liquid-liquid microextraction (TIL-UDLLμE) followed by electrothermal atomic absorption spectrometry (ETAAS). The Cd and Ni were complexed with ammonium pyrrolidinedithiocarbamate (APDC), extracted in ionic liquid drops, 1-butyl-3-methylimidazolium hexafluorophosphate [C4MIM][PF6]. The multivariate strategy was applied to estimate the optimum values of experimental variables influence the % recovery of analytes by TIL-UDLLμE method. At optimum experimental conditions, the limit of detection (3s) were 0.05 and 0.14μgL(-1) while relative standard deviations (% RSD) were 3.97 and 3.55 for Cd and Ni respectively. After extraction, the enhancement factors (EF) were 87 and 79 for Cd and Ni, respectively. The RSD for six replicates of 10μgL(-1) Cd and Ni were 3.97% and 3.55% respectively. To validate the proposed method, certified reference material (CRM) of Virginia tobacco leaves was analyzed, and the determined values of Cd and Ni were in good agreement with the certified values. The concentration of Cd and Ni in artificial saliva extracts corresponds to 39-52% and 21-32%, respectively, of the total contents of both elements in dry brown and black snuff products.

  17. Chemical stability of Lithium 2-trifluoromethyl-4,5-dicyanoimidazolide, an electrolyte salt for Li-ion cells

    SciTech Connect

    Shkrob, Ilya A.; Pupek, Krzysztof Z.; Gilbert, James A.; Trask, Stephen E.; Abraham, Daniel P.

    2016-12-01

    Lithium hexafluorophosphate (LiPF6) is ubiquitous in commercial lithium-ion batteries, but it is hydrolytically unstable and corrosive on electrode surfaces. Using a more stable salt would confer multiple benefits for high-voltage operation, but many such electrolyte systems facilitate anodic dissolution and pitting corrosion of aluminum current collectors that negate their advantages. Lithium 2-trifluoromethyl-4,5-dicyanoimidazolide (LiTDI) is a new salt that was designed specifically for high-voltage cells. In this study we demonstrate that in carbonate electrolytes, LiTDI prevents anodic dissolution of Al current collectors, which places it into a select group of corrosion inhibitors. However, we also demonstrate that LiTDI becomes reduced on lithiated graphite, undergoing sequential defluorination and yielding a thick and resistive solid-electrolyte interphase (SEI), which increases impedance and lowers electrode capacity. The mechanistic causes for this behavior are examined using computational chemistry methods in the light of recent spectroscopic studies. Here, we demonstrate that LiTDI reduction can be prevented by certain electrolyte additives, which include fluoroethylene carbonate, vinylene carbonate and lithium bis(oxalato)borate. This beneficial action is due to preferential reduction of these additives over LiTDI at a higher potential vs. Li/Li+, so the resulting SEI can prevent the direct reduction of LiTDI at lower potentials on the graphite electrode.

  18. Study on characteristics of PVDF/nano-clay composite polymer electrolyte using PVP as pore-forming agent

    NASA Astrophysics Data System (ADS)

    Dyartanti, Endah R.; Purwanto, Agus; Widiasa, I. Nyoman; Susanto, Heru

    2016-02-01

    Polyvinylidene fluoride (PVDF) based polymer electrolytes have a high dielectric constant, which can assist in greater ionization of lithium salts. The main advantages of PVDF are its durability in long battery operation and its ability to be a good ion conductor. However, the limitation of this polymer is its crystalline molecular structure. Dispersing nano-particles in the polymer matrix may improve the characteristics of the PVDF polymer. This paper aims to investigate the impact of nano-clay addition on the characteristics of PVDF polymer to be used as a polymer electrolyte membrane. In addition, the effect of poly(vinyl pyrrolidone) (PVP) is also investigated. The membrane was prepared by phase separation method whereas the polymer electrolyte membranes was prepared by immersing into 1 M lithium hexafluorophosphate (LiPF6) in ethylene carbonate/dimethyl carbonate (EC/DMC) electrolytes for 1 h. The membranes were characterized by scanning electron microscope (SEM), porosity and electrolyte uptake and performance in battery cell. The results showed that both nano-clay and PVP have significant impacts on the improvement of PVDF membranes to be used as polymer electrolyte.

  19. N-Vinylcarbazole as Versatile Photoinaddimer of Photopolymerization under Household UV LED Bulb (392 nm).

    PubMed

    Xiao, Pu; Lalevée, Jacques; Zhao, Jiacheng; Stenzel, Martina H

    2015-09-01

    N-vinylcarbazole (NVK) can act simultaneously as a photoinitiator, an additive, and a mono-mer (photoinaddimer) of photopolymerization upon exposure to the household ultraviolet (UV) light-emitting diode (LED) bulb (emission wavelength centered at 392 nm). Even though the light absorption spectrum of NVK exhibits weak overlapping with the emission spectrum of the UV LED, the active species (i.e., radicals and cations) can be generated from the interaction between NVK and diphenyliodonium hexafluorophosphate (Iod) under irradiation of this LED device, which is investigated by steady state photolysis and electron spin resonance spin-trapping methods. Interestingly, the generated radicals and cations from the NVK/Iod system demonstrate high efficiency to initiate the free radical photopolymerization of (meth)acrylates and the cationic photopolymerization of epoxide and divinyl ether under the UV LED irradiation, and the one-step simultaneous catonic/radical photopolymerization of expoxide/acrylate blend can lead to the formation of tack free polyacrylate/polyether-based interpenetrated polymer network film within 10 min even when the polymerization process is exposed to the atmosphere highlighting the high efficiency of the system to reduce the oxygen inhibition effect. More interestingly, NVK/Iod system can also initiate the photopolymerization of NVK under the UV LED irradiation to produce polyvinylcarbazole, and NVK acts as both a photoinitiator and a monomer in the system.

  20. Determining diffusion coefficients of ionic liquids by means of field cycling nuclear magnetic resonance relaxometry.

    PubMed

    Kruk, D; Meier, R; Rachocki, A; Korpała, A; Singh, R K; Rössler, E A

    2014-06-28

    Field Cycling Nuclear Magnetic Resonance (FC NMR) relaxation studies are reported for three ionic liquids: 1-ethyl-3- methylimidazolium thiocyanate (EMIM-SCN, 220-258 K), 1-butyl-3-methylimidazolium tetrafluoroborate (BMIM-BF4, 243-318 K), and 1-butyl-3-methylimidazolium hexafluorophosphate (BMIM-PF6, 258-323 K). The dispersion of (1)H spin-lattice relaxation rate R1(ω) is measured in the frequency range of 10 kHz-20 MHz, and the studies are complemented by (19)F spin-lattice relaxation measurements on BMIM-PF6 in the corresponding frequency range. From the (1)H relaxation results self-diffusion coefficients for the cation in EMIM-SCN, BMIM-BF4, and BMIM-PF6 are determined. This is done by performing an analysis considering all relevant intra- and intermolecular relaxation contributions to the (1)H spin-lattice relaxation as well as by benefiting from the universal low-frequency dispersion law characteristic of Fickian diffusion which yields, at low frequencies, a linear dependence of R1 on square root of frequency. From the (19)F relaxation both anion and cation diffusion coefficients are determined for BMIM-PF6. The diffusion coefficients obtained from FC NMR relaxometry are in good agreement with results reported from pulsed- field-gradient NMR. This shows that NMR relaxometry can be considered as an alternative route of determining diffusion coefficients of both cations and anions in ionic liquids.

  1. Functionalization of carbon nanotubes with water-insoluble porphyrin in ionic liquid: direct electrochemistry and highly sensitive amperometric biosensing for trichloroacetic acid.

    PubMed

    Tu, Wenwen; Lei, Jianping; Ju, Huangxian

    2009-01-01

    A functional composite of single-walled carbon nanotubes (SWNTs) with hematin, a water-insoluble porphyrin, was first prepared in 1-butyl-3-methylimidazolium hexafluorophosphate ([BMIM][PF(6)]) ionic liquid. The novel composite in ionic liquid was characterized by scanning electron microscopy, ultraviolet absorption spectroscopy, and electrochemical impedance spectroscopy, and showed a pair of direct redox peaks of the Fe(III)/Fe(II) couple. The composite-[BMIM][PF(6)]-modified glassy carbon electrode showed excellent electrocatalytic activity toward the reduction of trichloroacetic acid (TCA) in neutral media due to the synergic effect among SWNTs, [BMIM][PF(6)], and porphyrin, which led to a highly sensitive and stable amperometric biosensor for TCA with a linear range from 9.0x10(-7) to 1.4x10(-4) M. The detection limit was 3.8x10(-7) M at a signal-to-noise ratio of 3. The TCA biosensor had good analytical performance, such as rapid response, good reproducibility, and acceptable accuracy, and could be successfully used for the detection of residual TCA in polluted water. The functional composite in ionic liquid provides a facile way to not only obtain the direct electrochemistry of water-insoluble porphyrin, but also construct novel biosensors for monitoring analytes in real environmental samples.

  2. Redox chemistry of the Keggin heteropolyoxotungstate anion in ionic liquids.

    SciTech Connect

    Chiang, M.-H.; Dzielawa, J. A.; Dietz, M. L.; Antonio, M. R.; Chemistry

    2004-06-01

    The solid salts of the 1-ethyl-3-methylimidazolium and the 1-n-pentyl-3-methylimidazolium cations, abbreviated [C{sub 2}mim]{sup +} and [C{sub 5}mim]{sup +}, respectively, of the Keggin heteropolyanion, {alpha}-[PW{sub 12}O{sub 40}]{sup 3-}, were prepared. Cyclic voltammetry (CV) and differential pulse voltammetry (DPV) measurements of both [C{sub n}mim]{sub 3}[{alpha}-PW{sub 12}O{sub 40}] salts (for n=2 and 5) were performed in acetonitrile containing either tetra-n-butylammonium hexafluorophosphate, abbreviated TBAPF{sub 6}, or the corresponding [C{sub n}mim]BF{sub 4} ionic liquids (ILs) as electrolytes. The results are compared with the corresponding data obtained in the neat [C{sub n}mim]BF{sub 4} ILs without addition of other electrolytes. The effects of countercation and supporting electrolyte on the voltammetry of the Keggin ion {alpha}-[PW{sub 12}O{sub 40}]{sup 3-} are interpreted as resulting from an amalgamation of isomerization, ion-association, and redox processes. The combination of the unique solvent/electrolyte properties of ILs with the well-known electrochemistry of molecular polyoxometalates (POMs) like the Keggin aanion leads to redox behavior that may have impact on the research and technology of catalytic and energy-storage phenomena.

  3. Bottom-up electrochemical preparation of solid-state carbon nanodots directly from nitriles/ionic liquids using carbon-free electrodes and the applications in specific ferric ion detection and cell imaging

    NASA Astrophysics Data System (ADS)

    Niu, Fushuang; Xu, Yuanhong; Liu, Mengli; Sun, Jing; Guo, Pengran; Liu, Jingquan

    2016-03-01

    Carbon nanodots (C-dots), a new type of potential alternative to conventional semiconductor quantum dots, have attracted numerous attentions in various applications including bio-chemical sensing, cell imaging, etc., due to their chemical inertness, low toxicity and flexible functionalization. Various methods including electrochemical (EC) methods have been reported for the synthesis of C-dots. However, complex procedures and/or carbon source-containing electrodes are often required. Herein, solid-state C-dots were simply prepared by bottom-up EC carbonization of nitriles (e.g. acetonitrile) in the presence of an ionic liquid [e.g. 1-butyl-3-methylimidazolium hexafluorophosphate (BMIMPF6)], using carbon-free electrodes. Due to the positive charges of BMIM+ on the C-dots, the final products presented in a precipitate form on the cathode, and the unreacted nitriles and BMIMPF6 can be easily removed by simple vacuum filtration. The as-prepared solid-state C-dots can be well dispersed in an aqueous medium with excellent photoluminescence properties. The average size of the C-dots was found to be 3.02 +/- 0.12 nm as evidenced by transmission electron microscopy. Other techniques such as UV-vis spectroscopy, fluorescence spectroscopy, X-ray photoelectron spectroscopy and atomic force microscopy were applied for the characterization of the C-dots and to analyze the possible generation mechanism. These C-dots have been successfully applied in efficient cell imaging and specific ferric ion detection.Carbon nanodots (C-dots), a new type of potential alternative to conventional semiconductor quantum dots, have attracted numerous attentions in various applications including bio-chemical sensing, cell imaging, etc., due to their chemical inertness, low toxicity and flexible functionalization. Various methods including electrochemical (EC) methods have been reported for the synthesis of C-dots. However, complex procedures and/or carbon source-containing electrodes are often

  4. Why is the electroanalytical performance of carbon paste electrodes involving an ionic liquid binder higher than paraffinic binders? A simulation investigation.

    PubMed

    Ghatee, M H; Namvar, S; Zolghadr, A R; Moosavi, F

    2015-10-14

    Recently, carbon paste electrodes (CPE) fabricated using an ionic liquid (IL) binder have shown enhanced electroanalytical performance over conventional paraffinic binders. Molecular dynamics (MD) simulations of graphite mixed with ionic liquid and with paraffin binder can unravel the potential atomistic factors responsible for such enhancement. Based on an experimentally optimized binder/graphite mass ratio, which has been reported to be crucial for such a performance, comprehensive simulations (at 323 K) are performed with the ensembles involving an ionic liquid binder (1-butyl-3-methylimidazolium hexafluorophosphate, [C4mim]PF6) and a paraffin binder (n-C20H42) mixed with graphite comprising large-size hexagonal-shaped double graphene plates. Structural analysis indicates both binders form only a monolayer on the graphite surface, covering the surface locally by IL but all-encompassing by paraffin. With charged and uncharged graphite, the IL monolayer tends to cover mainly the graphite center without approaching the edge planes. On the contrary, a monolayer of the paraffin binder covers uniformly the center, near the center, and the edge planes. Cations and anions of the IL form well-defined two dimensional pentagonal matrixes with characteristic high adsorption energy, almost 2.4 times higher than paraffin adsorption. The cation and anion coordination ability of the IL is responsible for such a local distribution. The simulation of these phenomena under experimental conditions unravels strong two-dimensional coordination properties inherent to the ionic liquid when distributed over the graphite surface. This direct MD simulation comparison of the IL properties with an organic liquid counterpart, made for the first time, can be used to explain the high electroanalytical performance (electron transfer) of CPEs involving an IL binder over paraffin binders.

  5. Determination of Aromatic Amines Using Solid-Phase Microextraction Based on an Ionic Liquid-Mediated Sol-Gel Technique.

    PubMed

    Abbasi, Vajihe; Sarafraz-Yazdi, Ali; Amiri, Amirhassan; Vatani, Hossein

    2016-04-01

    A headspace solid-phase microextraction (HS-SPME) method was developed for isolation of monocyclic aromatic amines from water samples followed by gas chromatography-flame ionization detector (GC-FID). In this work, the effect of the presence of ionic liquid (namely, 1-hexyl-3-methyl-imidazolium hexafluorophosphate [C6MIM][PF6]) was investigated in the sol-gel coating solutions on the morphology and extraction behavior of the resulting hybrid organic-inorganic sol-gel sorbents utilized in SPME. Hydroxy-terminated poly(dimethylsiloxane) (PDMS) was used as the sol-gel active organic component for sol-gel hybrid coatings. Two different coated fibers that were prepared are PDMS and PDMS-IL ([C6MIM][PF6]) fibers. Under the optimal conditions, the method detection limits (S/N = 3) with PDMS-IL were in the range of 0.001-0.1 ng/mL and the limits of quantification (S/N = 10) between 0.005 and 0.5 ng/mL. The relative standard deviations for one fiber (n = 5) were obtained from 3.1 up to 8.5% and between fibers or batch to batch (n = 3) in the range of 5.3-10.1%. The developed method was successfully applied to real water and juice fruits samples while the relative recovery percentages obtained for the spiked water samples at 0.1 ng/mL were from 83.3 to 95.0%.

  6. Probing structural patterns of ion association and solvation in mixtures of imidazolium ionic liquids with acetonitrile by means of relative (1)H and (13)C NMR chemical shifts.

    PubMed

    Marekha, Bogdan A; Kalugin, Oleg N; Bria, Marc; Idrissi, Abdenacer

    2015-09-21

    Mixtures of ionic liquids (ILs) with polar aprotic solvents in different combinations and under different conditions (concentration, temperature etc.) are used widely in electrochemistry. However, little is known about the key intermolecular interactions in such mixtures depending on the nature of the constituents and mixture composition. In order to systematically address the intermolecular interactions, the chemical shift variation of (1)H and (13)C nuclei has been followed in mixtures of imidazolium ILs 1-n-butyl-3-methylimidazolium tetrafluoroborate (BmimBF4), 1-n-butyl-3-methylimidazolium hexafluorophosphate (BmimPF6), 1-n-butyl-3-methylimidazolium trifluoromethanesulfonate (BmimTfO) and 1-n-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide (BmimTFSI) with molecular solvent acetonitrile (AN) over the entire composition range at 300 K. The concept of relative chemical shift variation is proposed to assess the observed effects on a unified and unbiased scale. We have found that hydrogen bonds between the imidazolium ring hydrogen atoms and electronegative atoms of anions are stronger in BmimBF4 and BmimTfO ILs than those in BmimTFSI and BmimPF6. Hydrogen atom at position 2 of the imidazolium ring is substantially more sensitive to interionic hydrogen bonding than those at positions 4-5 in the case of BmimTfO and BmimTFSI ILs. These hydrogen bonds are disrupted upon dilution in AN due to ion dissociation which is more pronounced at high dilutions. Specific solvation interactions between AN molecules and IL cations are poorly manifested.

  7. Effect of Partition of Photo-Initiator Components and Addition of Iodonium Salt on the Photopolymerization of Phase-Separated Dental Adhesive

    NASA Astrophysics Data System (ADS)

    Abedin, Farhana; Ye, Qiang; Song, Linyong; Ge, Xueping; Camarda, Kyle; Spencer, Paulette

    2016-04-01

    The polymerization kinetics of physically separated hydrophobic- and hydrophilic-rich phases of a model dental adhesive have been investigated. The two phases were prepared from neat resin containing 2-hydroxyethyl methacrylate and bisphenol A glycerolate dimethacrylate (BisGMA) in the ratio of 45:55 (wt./wt.). Neat resins containing various combinations of popular photo-initiating compounds, e.g., camphoquinone (CQ), ethyl 4-(dimethylamino)benzoate (EDMAB), 2-(dimethylamino)ethyl methacrylate (DMAEMA), and diphenyliodonium hexafluorophosphate (DPIHP), were prepared. To obtain the two phases, 33 wt.% of deuterium oxide (D2O) was added to the neat resins. This amount of D2O exceeded the miscibility limit for the resins. The concentration of each component of the photo-initiating system in the two phases was quantified by high-performance liquid chromatography (HPLC). When combined with CQ, DMAEMA is less efficient as a co-initiator compared to EDMAB. The addition of DPIHP as the third component into either CQ/EDMAB or CQ/DMAEMA photo-initiating systems led to comparable performance in both the hydrophobic- and hydrophilic-rich phases. The addition of the iodonium salt significantly improved the photopolymerization of the hydrophilic-rich phase; the latter exhibited extremely poor polymerization when the iodonium salt was not included in the formulation. The partition concentration of EDMAB in the hydrophilic-rich phase was significantly lower than that of DMAEMA or DPIHP. This study indicates the need for a combination of hydrophobic/hydrophilic photosensitizer and addition of iodonium salt to improve polymerization within the hydrophilic-rich phase of the dental adhesive.

  8. Gold-ionic liquid nanofluids with preferably tribological properties and thermal conductivity

    NASA Astrophysics Data System (ADS)

    Wang, Baogang; Wang, Xiaobo; Lou, Wenjing; Hao, Jingcheng

    2011-12-01

    Gold/1-butyl-3-methylimidazolium hexafluorophosphate (Au/[Bmim][PF6]) nanofluids containing different stabilizing agents were fabricated by a facile one-step chemical reduction method, of which the nanofluids stabilized by cetyltrimethylammonium bromide (CTABr) exhibited ultrahighly thermodynamic stability. The transmission electron microscopy, UV-visible absorption, Fourier transform infrared, and X-ray photoelectron characterizations were conducted to reveal the stable mechanism. Then, the tribological properties of these ionic liquid (IL)-based gold nanofluids were first investigated in more detail. In comparison with pure [Bmim][PF6] and the nanofluids possessing poor stability, the nanofluids with high stability exhibited much better friction-reduction and anti-wear properties. For instance, the friction coefficient and wear volume lubricated by the nanofluid with rather low volumetric concentration (1.02 × 10-3%) stabilized by CTABr under 800 N are 13.8 and 45.4% lower than that of pure [Bmim][PF6], confirming that soft Au nanoparticles (Au NPs) also can be excellent additives for high performance lubricants especially under high loads. Moreover, the thermal conductivity (TC) of the stable nanofluids with three volumetric fraction (2.55 × 10-4, 5.1 × 10-4, and 1.02 × 10-3%) was also measured by a transient hot wire method as a function of temperature (33 to 81°C). The results indicate that the TC of the nanofluid (1.02 × 10-3%) is 13.1% higher than that of [Bmim][PF6] at 81°C but no obvious variation at 33°C. The conspicuously temperature-dependent and greatly enhanced TC of Au/[Bmim][PF6] nanofluids stabilized by CTABr could be attributed to micro-convection caused by the Brownian motion of Au NPs. Our results should open new avenues to utilize Au NPs and ILs in tribology and the high-temperature heat transfer field.

  9. Simple and sensitive electrogenerated chemiluminescence peptide-based biosensor for detection of matrix metalloproteinase 2 released from living cells.

    PubMed

    Dang, Qian; Gao, Hongfang; Li, Zhejian; Qi, Honglan; Gao, Qiang; Zhang, Chengxiao

    2016-10-01

    A simple and sensitive electrogenerated chemiluminescence biosensor was developed to monitor matrix metalloproteinase 2 (MMP-2) by employing a specific peptide (CGPLGVRGK) as a molecular recognition substrate. Bis(2,2'-bipyridine)-4'-methyl-4-carboxybipyridine-ruthenium N-succinimidyl ester-bis(hexafluorophosphate) (Ru(bpy)2(mcbpy-O-Su-ester)(PF6)2 (Ru1) was used as ECL-emitting species and covalently labeled onto the peptide through NH2-containing lysine on the peptide via acylation reaction to form Ru1-peptide as an ECL probe. An ECL peptide-based biosensor was fabricated by self-assembling the ECL probe onto the surface of gold electrode. MMP-2 can specifically cleave the Ru1-peptide on the electrode surface, which led the partly Ru1-peptide to leave the electrode surface and resulted in the decrease of the ECL intensity obtained from the resulted electrode in 0.1 M phosphate-buffered saline (pH 7.4) containing tri-n-propylamine. The decreased ECL intensity was piecewise linear to the concentration of MMP-2 in the range from 1 to 500 ng/mL. Moreover, the ECL biosensor is successfully applied to detection of MMP-2 secreted by living cell, such as HeLa cells. Additionally, the biosensor was also applied to the evaluation of matrix metalloproteinase inhibitors. The strategy presented here is promising for other disease-related matrix metalloproteinase assay and matrix metalloproteinase inhibitor profiling with sensitivity and simplicity. Graphical Abstract Detection of MMP-2 released from living cells by ECL peptide-based biosensor.

  10. Modeling the formation and reactions of benzene metabolites.

    PubMed

    Golding, Bernard T; Barnes, Martine L; Bleasdale, Christine; Henderson, Alistair P; Jiang, Dong; Li, Xin; Mutlu, Esra; Petty, Hannah J; Sadeghi, Majid M

    2010-03-19

    One or more of the muconaldehyde isomers is a putative product of benzene metabolism. As muconaldehydes are highly reactive dienals and potentially mutagenic they might be relevant to the carcinogenicity of benzene. Muconaldehydes may be derived through the action of a cytochrome P450 mono-oxygenase on benzene oxide-oxepin, which are established metabolites of benzene. Oxidation of benzene oxide-oxepin either by the one-electron oxidant cerium(IV) ammonium nitrate (CAN) or by iron(III) tris(1,10-phenanthroline) hexafluorophosphate in acetone at -78 degrees C or acetonitrile at -40 degrees C gave (E,Z)-muconaldehyde, which was a single diastereoisomer according to analysis by (1)H NMR spectroscopy. Reaction of toluene-1,2-oxide/2-methyloxepin with CAN gave (2E,4Z)-6-oxo-hepta-2,4-dienal. Similarly, the action of CAN on 1,6-dimethylbenzene oxide-2,7-dimethyloxepin gave (3Z,5E)-octa-3,5-diene-2,7-dione. In vivo, benzene oxide-oxepin could suffer one-electron oxidation by cytochrome P450 mono-oxygenase giving (E,Z)-muconaldehyde. The observations presented may be relevant to the toxicology of benzene oxide-oxepin and other arene oxide-oxepins as we have previously shown that (E,Z)-muconaldehyde, analogously to (Z,Z)-muconaldehyde, affords pyrrole adducts with the exocyclic amino groups of the DNA bases adenine and guanine. Independent of their possible toxicological significance, the experiments described provide preparatively useful routes to (E,Z)-muconaldehyde and its congeners. Methods are also described for the trapping and analysis of reactive benzene metabolites, e.g. using the Diels-Alder reaction with the dienophile 4-phenyl-1,2,4-triazoline-3,5-dione to trap arene oxides and with the diene 1,3-diphenylisobenzofuran to trap enals.

  11. Ionic liquid-assisted liquid-phase microextraction based on the solidification of floating organic droplets combined with high performance liquid chromatography for the determination of benzoylurea insecticide in fruit juice.

    PubMed

    Yang, Miyi; Zhang, Panjie; Hu, Lu; Lu, Runhua; Zhou, Wenfeng; Zhang, Sanbing; Gao, Haixiang

    2014-09-19

    A green, simple, and efficient method, ionic liquid-assisted liquid-liquid microextraction based on the solidification of floating organic droplets (ILSFOD-LLME) collected via a bell-shaped collection device (BSCD) coupled to high performance liquid chromatography with a variable-wavelength detector, was developed for the preconcentration and analysis of seven benzoylurea insecticides (BUs) in fruit juice. In the proposed method, the low-density solvent 1-dodecanol and the ionic liquid trihexyl(tetradecyl)phosphonium hexafluorophosphate ([P14, 6, 6, 6]PF6) were used as extractant. The extraction solvent droplet was easily collected and separated by the BSCD without centrifugation. The experimental parameters were optimized by the one-factor-at-a-time approach and were followed using an orthogonal array design. The results indicated the different effects of each parameter for extraction efficiency. Under the optimal conditions in the water model, the limits of detection for the analytes varied from 0.03 to 0.28μgL(-1). The enrichment factors ranged from 160 to 246. Linearities were achieved for hexaflumuron and flufenoxuron in the range of 0.5-500μgL(-1), for triflumuron, lufenuron and diafenthiuron in the range of 1-500μgL(-1), and for diflubenzuron and chlorfluazuron in the range of 5-500μgL(-1); the correlation coefficients for the BUs ranged from 0.9960 to 0.9990 with recoveries of 75.6-113.9%. Finally, the developed technique was successfully applied to real fruit juice with acceptable results. The relative standard deviations (RSDs) of the seven BUs at two spiked levels (50 and 200μgL(-1)) varied between 0.1% and 7.3%.

  12. New insights into the thermal behaviour of organic ionic plastic crystals: magnetic resonance imaging of polycrystalline morphology alterations induced by solid-solid phase transitions.

    PubMed

    Romanenko, Konstantin; Pringle, Jennifer M; O'Dell, Luke A; Forsyth, Maria

    2015-07-15

    Organic ionic plastic crystals (OIPCs) show strong potential as solid-state electrolytes for lithium battery applications, demonstrating promising electrochemical performance and eliminating the need for a volatile and flammable liquid electrolyte. The ionic conductivity (σ) in these systems has recently been shown to depend strongly on polycrystalline morphology, which is largely determined by the sample's thermal history. [K. Romanenko et al., J. Am. Chem. Soc., 2014, 136, 15638]. Tailoring this morphology could lead to conductivities sufficiently high for battery applications, so a more complete understanding of how phenomena such as solid-solid phase transitions can affect the sample morphology is of significant interest. Anisotropic relaxation of nuclear spin magnetisation provides a new MRI based approach for studies of polycrystalline materials at both a macroscopic and molecular level. In this contribution, morphology alterations induced by solid-solid phase transitions in triisobutyl(methyl)phosphonium bis(fluorosulfonyl)imide (P1444FSI) and diethyl(methyl)(isobutyl)phosphonium hexafluorophosphate (P1224PF6) are examined using magnetic resonance imaging (MRI), alongside nuclear magnetic resonance (NMR) spectroscopy, diffusion measurements and conductivity data. These observations are linked to molecular dynamics and structural behaviour crucial for the conductive properties of OIPCs. A distinct correlation is established between the conductivity at a given temperature, σ(T), and the intensity of the narrow NMR signal that is attributed to a mobile fraction, fm(T), of ions in the OIPC. To explain these findings we propose an analogy with the well-studied relationship between permeability (k) and void fraction (θ) in porous media, with k(θ) commonly quantified by a power-law dependence that can also be employed to describe σ(fm).

  13. Impact of ionic liquid-modified multiwalled carbon nanotubes on the crystallization behavior of poly(vinylidene fluoride).

    PubMed

    Xing, Chenyang; Zhao, Liping; You, Jichun; Dong, Wenyong; Cao, Xiaojun; Li, Yongjin

    2012-07-19

    The impact of pristine multiwalled carbon nanotubes (MWCNTs), an ionic liquid (IL), 1-butyl-3-methylimidazolium hexafluorophosphate [BMIM][PF6], and the ionic liquid-modified MWCNTs (IL-MWCNTs) on the crystallization behavior of melt-crystallized poly(vinylidene fluoride) (PVDF) has been investigated. Pristine MWCNTs accelerate crystallization of PVDF as an efficient nucleation agent, while the formed crystals are mainly nonpolar α crystal form with few polar β crystals. Incorporation of only ionic liquid results in depression of the PVDF melt crystallization rate due to the miscibility of IL with PVDF but leads to a higher content of polar crystals (β and γ forms) than MWCNTs. The ionic liquid and MWCNTs show significant synergetic effects on both the nucleation and the formation of polar crystals for PVDF by melt crystallization. Addition of IL-MWCNTs not only improves the MWCNTs dispersion in PVDF matrix but also increases the overall crystallization rate of PVDF drastically. More important, the melt-crystallized PVDF nanocomposites with IL-MWCNTs show 100% polar polymorphs but no α crystal forms. To the best of our knowledge, this is the first report on the achievements of full polar crystal form in the melt-crystallized PVDF without mechanical deformation or electric field. The IL to MWCNTs ratio and the IL-MWCNTs loading content effects on the crystallization behavior of PVDF in the nanocomposites were also studied. It is considered that the specific interactions between >CF2 with the planar cationic imidazolium ring wrapped on the MWCNTs surface lead to the full zigzag conformations of PVDF; thus, nucleation in polar crystals (β and γ forms) lattice is achieved and full polar crystals are obtained by subsequent crystal growth from the nuclei.

  14. Aggregation behavior of Triton X-100 with a mixture of two room-temperature ionic liquids: can we identify the mutual penetration of ionic liquids in ionic liquid containing micellar aggregates?

    PubMed

    Rao, Vishal Govind; Mandal, Sarthak; Ghosh, Surajit; Banerjee, Chiranjib; Sarkar, Nilmoni

    2012-11-29

    In this manuscript, we have characterized two different micellar aggregates containing all nonvolatile components. We have shown (i) the effect of ethylammonium nitrate (EAN) addition on the properties of micellar solution of Triton X-100 in 1-butyl-3-methylimidazolium hexafluorophosphate (bmimPF(6)) and (ii) the effect of bmimPF(6) addition on the properties of micellar solution of Triton X-100 in EAN. To investigate the effect, we have used (1)H NMR, pulsed-field gradient spin-echo NMR (PFGSE NMR), and methyl orange (MO) and coumarin 153 (C-153) as absorption and emission probes, respectively. The penetration of added EAN inside the Triton X-100/bmimPF(6) micellar aggregates is indicated by (i) red shift in both the absorption spectra of MO and emission spectra of C-153 and (ii) downfield shift of proton signals of ethylene oxide units in Triton X-100. On the other hand, (1)H NMR and PFGSE NMR indicates the penetration of added bmimPF(6) inside the Triton X-100/EAN micellar aggregates. However, the constancy of both the absorption spectra of MO and emission spectra of C-153 indicates that the microenvironment around the probe molecules remains unaffected. We have also investigated the effect of micelle formation and the effect of penetration of ionic liquids (ILs) in micellar aggregates, on the solvation dynamics of C-153. The solvent relaxation around C-153 gets retarded on going from neat ILs to the micellar solution of Triton X-100 in ILs. In addition to this, we have also observed that with the addition of EAN in Triton X-100/bmimPF(6) micellar aggregates the solvation dynamics becomes faster, whereas with the addition of bmimPF(6) in Triton X-100/EAN micellar aggregates we did not observe any notable change in solvation dynamics. This observation further supports the conclusions drawn from UV-visible and NMR studies.

  15. Thiopeptide synthesis. {alpha}-amino thionoacid derivatives of nitrobenzotriazole as thioacylating agents

    SciTech Connect

    Shalaby, M.A.; Grote, C.W.; Rapoport, H.

    1996-12-13

    There has been considerable interest recently in the synthesis and properties of thiopeptides in which the -CSNH- group replaces one or more peptide bonds. These modified peptides have demonstrated increased activity in vivo as biological response modifiers, neuro-effectors, and immunomodulators due to the stability of their thioamide bonds toward enzymatic degradation as compared to that of their oxygenated counterpart. Synthetic routes employed to prepare these thiopeptides included replacement of oxygen by sulfur using P{sub 4}S{sub 10} or Lawesson`s phosphetane disulfide reagent, and thioesters or dithioesters of N-protected amino acids. Several procedures also have been reported for monothionation of peptides using N-protected amino monothioacids and benzotriazolyloxytris(pyrrolidino) phosphonium hexafluorophosphate (PYBOP) and some of its derivatives. Unfortunately, these methods displayed lack of reaction site specificity, low yields and purity because of side reactions, and loss of enantiomeric integrity in the final product, apparently because of racemization induced by the thioacylating agents. Recently, major improvement was described for the site specific incorporation of thioamide linkages into a growing peptide under mild conditions using thioacylbenzimidazolinones of amino acid derivatives as thioacylating agents. This method proceeds with about 2% loss of enantiomeric purity, as demonstrated by HPLC analysis of the reaction product 10a, formed in reaction with {alpha}-methylbenzylamine. This procedure, although superior to previous methods, still suffers from the formation of benzimidazole 2 as a significant byproduct, and the overall yield for the four-step process was only about 20%. Furthermore, recent attempt to use this procedure failed due to the limited reactivity of the benzimidazolinone 4 as a thioacylating agent. To overcome these limitations, the authors have developed a new method for thiopeptide synthesis. 12 refs.

  16. Gold-ionic liquid nanofluids with preferably tribological properties and thermal conductivity.

    PubMed

    Wang, Baogang; Wang, Xiaobo; Lou, Wenjing; Hao, Jingcheng

    2011-03-28

    Gold/1-butyl-3-methylimidazolium hexafluorophosphate (Au/[Bmim][PF6]) nanofluids containing different stabilizing agents were fabricated by a facile one-step chemical reduction method, of which the nanofluids stabilized by cetyltrimethylammonium bromide (CTABr) exhibited ultrahighly thermodynamic stability. The transmission electron microscopy, UV-visible absorption, Fourier transform infrared, and X-ray photoelectron characterizations were conducted to reveal the stable mechanism. Then, the tribological properties of these ionic liquid (IL)-based gold nanofluids were first investigated in more detail. In comparison with pure [Bmim][PF6] and the nanofluids possessing poor stability, the nanofluids with high stability exhibited much better friction-reduction and anti-wear properties. For instance, the friction coefficient and wear volume lubricated by the nanofluid with rather low volumetric concentration (1.02 × 10-3%) stabilized by CTABr under 800 N are 13.8 and 45.4% lower than that of pure [Bmim][PF6], confirming that soft Au nanoparticles (Au NPs) also can be excellent additives for high performance lubricants especially under high loads. Moreover, the thermal conductivity (TC) of the stable nanofluids with three volumetric fraction (2.55 × 10-4, 5.1 × 10-4, and 1.02 × 10-3%) was also measured by a transient hot wire method as a function of temperature (33 to 81°C). The results indicate that the TC of the nanofluid (1.02 × 10-3%) is 13.1% higher than that of [Bmim][PF6] at 81°C but no obvious variation at 33°C. The conspicuously temperature-dependent and greatly enhanced TC of Au/[Bmim][PF6] nanofluids stabilized by CTABr could be attributed to micro-convection caused by the Brownian motion of Au NPs. Our results should open new avenues to utilize Au NPs and ILs in tribology and the high-temperature heat transfer field.

  17. Direct electrochemistry with enhanced electrocatalytic activity of hemoglobin in hybrid modified electrodes composed of graphene and multi-walled carbon nanotubes.

    PubMed

    Sun, Wei; Cao, Lili; Deng, Ying; Gong, Shixing; Shi, Fan; Li, Gaonan; Sun, Zhenfan

    2013-06-05

    A graphene (GR) and multi-walled carbon nanotubes (MWCNT) hybrid was prepared and modified on a 1-hexylpyridinium hexafluorophosphate based carbon ionic liquid electrode (CILE). Hemoglobin (Hb) was immobilized on GR-MWCNT/CILE surface with Nafion as the film forming material and the modified electrode was denoted as Nafion/Hb-GR-MWCNT/CILE. Spectroscopic results revealed that Hb molecules retained its native structure in the GR-MWCNT hybird. Electrochemical behaviors of Hb were carefully investigated by cyclic voltammetry with a pair of well-defined redox peaks obtained, which indicated that direct electron transfer of Hb was realized in the hybrid modified electrode. The result could be attributed to the synergistic effects of GR-MWCNT hybrid with enlarged surface area and improved conductivity through the formation of a three-dimensional network. Electrochemical parameters of the immobilized Hb on the electrode surface were further calculated with the results of the electron transfer number (n) as 1.03, the charge transfer coefficient (a) as 0.58 and the electron-transfer rate constant (ks) as 0.97 s(-1). The Hb modified electrode showed good electrocatalytic ability toward the reduction of different substrates such as trichloroacetic acid in the concentration range from 0.05 to 38.0 mmol L(-1) with a detection limit of 0.0153 mmol L(-1) (3σ), H2O2 in the concentration range from 0.1 to 516.0 mmol L(-1) with a detection limit of 34.9 nmol/L (3σ) and NaNO2 in the concentration range from 0.5 to 650.0 mmol L(-1) with a detection limit of 0.282 μmol L(-1) (3σ). So the proposed electrode had the potential application in the third-generation electrochemical biosensors without mediator.

  18. Vortex-assisted ionic liquid-based dispersive liquid-liquid microextraction for assessment of chromium species in artificial saliva extract of different chewing tobacco products.

    PubMed

    Akhtar, Asma; Kazi, Tasneem Gul; Afridi, Hassan Imran; Musharraf, Syed Ghulam; Talpur, Farah Naz; Khan, Noman; Bilal, Muhammad; Khan, Mustafa

    2016-12-01

    A novel dispersive liquid-liquid microextraction (ILDLLμE) method using an extracting solvent (ionic liquid) and dispersant (Triton X-114) was developed for the separation and preconcentration of hexavalent chromium (Cr(6+)) in artificial saliva extract (ASE) of chewing tobacco products, gutkha, and mainpuri (n = 23). In the proposed method, the extraction of Cr(6+) was accomplished by using ammonium pyrrolidinedithiocarbamate (APDC) as complexing agent and 1-butyl-3-methylimidazolium hexafluorophosphate [C4MIM] [PF6] as extracting solvent. The tiny droplet of metal chelate was then dispersed into TX-114 emulsion, using vortex mixer. Various parameters such as concentration of APDC, pH of the solution, volume of [C4MIM] [PF6], and TX-114 as well as extraction time were studied. Under the most favorable conditions, the limit of detection was found to be 0.068 μg/L with the relative standard deviation <5 %. The enrichment factor of developed method was found as 62.5, and method has been effectively applied for the analysis of Cr species in artificial saliva extract of gutkha and mainpuri products. The Cr(6+) was quantitatively recovered (<97 %) under optimal conditions, while the recovery of trivalent specie (Cr(3+)), at the same experimental conditions, was observed to be <5 %. The Cr(3+) was determined by the difference of total Cr and Cr(6+) in artificial saliva extract of selected STP. Health risks associated with the intake of total Cr in gutkha and mainpuri were assessed in terms of estimated daily intake, such as carcinogenic and noncarcinogenic risks. Estimated daily intake of Cr via chewing 10 g/day of gutkha and mainpuri was found to be below the maximum tolerable daily intake, whereas the calculated risk of cancer for Cr was observed in the acceptable range of 10E(-6)-10E(-4), except some brands of gutkha. Graphical Abstract ᅟ.

  19. Dynamic phase change and local structures in IL-containing mixtures: classical MD simulations and experiments.

    PubMed

    Wu, Yang; Wang, Xia; Liu, Qiaozhen; Ma, Xiaoxue; Fang, Dawei; Jiang, Xuefei; Guan, Wei

    2017-01-25

    The dynamic phase change between a homogeneous mixture and a liquid-liquid biphase and separation of phases are explored in three-component mixtures composed of 1-butyl-3-methylimidazolium hexafluorophosphate ([Bmim][PF6]), 1-butyl-3-methylimidazolium tetrafluoroborate ([Bmim][BF4]), and water through a classical simulation method and experiment. Different experimental and theoretical tools, including density measurement, dynamic light scattering study, radial distribution, mean square displacement, an interstice model, and statistical function, are used to describe the structural modifications of the ions as a function of solution concentration. An analysis of the relation between the phase and the state of the component ions indicates that the phase separation pattern is governed by the hydrophilicity/hydrophobicity of anions. We proposed the existence of a critical point, that is, 1 : 3 : 8 for [Bmim][PF6]/[Bmim][BF4]/H2O (mole fraction). Before this critical point, obvious phase separation was seen in the mixtures. The separation phase became homogeneous with the addition of [Bmim][BF4] after this critical point. However, this homogeneous mixed solution was phase separated again upon the addition of [Bmim][PF6] or water. The existing nanostructures were present in the [Bmim][PF6]/[Bmim][BF4]/H2O mixtures, and their size abruptly decreased close to the critical point. We provided evidence of the formation of double salt ionic liquids of [Bmim][PF6]0.25[BF4]0.75·2H2O and discussed the interactions involved in these systems by examining their physicochemical properties. The ionic phase response of such three-component mixtures could be useful in various applications, especially in the dynamic control of extraction/separation processing.

  20. Liquid/liquid interface layering of 1-butanol and [bmim]PF6 ionic liquid: a nonlinear vibrational spectroscopy and molecular dynamics simulation study.

    PubMed

    Iwahashi, Takashi; Ishiyama, Tatsuya; Sakai, Yasunari; Morita, Akihiro; Kim, Doseok; Ouchi, Yukio

    2015-10-14

    IR-visible sum-frequency generation (IV-SFG) vibrational spectroscopy and a molecular dynamics (MD) simulation were used to study the local layering order at the interface of 1-butanol-d9 and 1-butyl-3-methylimidazolium hexafluorophosphate ([bmim]PF6), a room-temperature ionic liquid (RTIL). The presence of a local non-polar layer at the interface of the two polar liquids was successfully demonstrated. In the SFG spectra of 1-butanol-d9, we observed significant reduction and enhancement in the strength of the CD3 symmetric stretching (r(+)) mode and the antisymmetric stretching (r(-)) mode peaks, respectively. The results can be well explained by the presence of an oppositely oriented quasi-bilayer structure of butanol molecules, where the bottom layer is strongly bound by hydrogen-bonding with the PF6(-) anion. MD simulations reveal that the hydrogen-bonding of butanol with the PF6(-) anion causes the preferential orientation of the butanols; the restriction on the rotational distribution of the terminal methyl group along their C3 axis enhances the r(-) mode. As for the [bmim](+) cations, the SFG spectra taken within the CH stretch region indicate that the butyl chain of [bmim](+) points away from the bulk RTIL phase to the butanol phase at the interface. Combining the SFG spectroscopy and MD simulation results, we propose an interfacial model structure of layering, in which the butyl chains of the butanol molecules form a non-polar interfacial layer with the butyl chains of the [bmim](+) cations at the interface.

  1. Solution-Processable Ionic Liquid as an Independent or Modifying Electron Transport Layer for High-Efficiency Perovskite Solar Cells.

    PubMed

    Wu, Qiliang; Zhou, Weiran; Liu, Qing; Zhou, Pengcheng; Chen, Tao; Lu, Yalin; Qiao, Qiquan; Yang, Shangfeng

    2016-12-21

    Inorganic metal oxide, especially TiO2, has been commonly used as an electron transport layer (ETL) in regular-structure (n-i-p) planar heterojunction perovskite solar cells (PHJ-PSCs) but generally suffers from high electron recombination rate and incompatibility with low-temperature solution processability. Herein, by applying an ionic liquid (IL, 1-ethyl-3-methylimidazolium hexafluorophosphate ([EMIM]PF6)) as either a TiO2-modifying interlayer or an independent ETL, we investigated systematically IL interface engineering for PHJ-PSCs. Upon spin-coating [EMIM]PF6-IL onto TiO2 ETL as a modification layer, the average power conversion efficiency (PCE) of CH3NH3PbI3 PHJ-PSC devices reaches 18.42 ± 0.65%, which dramatically surpasses that based on commonly used TiO2 ETL (14.20 ± 0.43%), and the highest PCE (19.59%) is almost identical to that of the record PCE for planar CH3NH3PbI3 PSCs (19.62%) reported very recently. On the other hand, by applying [EMIM]PF6-IL as an independent ETL, we achieved an average PCE of 13.25 ± 0.55%, and the highest PCE (14.39%) approaches that obtained for PHJ-PSCs based on independent TiO2 ETL (14.96%). Both IL interface engineering methods reveal the effective electron transport of [EMIM]PF6-IL. The effects of [EMIM]PF6-IL on the surface morphology, crystallinity, and optical absorption of the perovskite film and the interface between the perovskite layer and substrate were investigated and compared with the case of independent TiO2 ETL, revealing the role of [EMIM]PF6-IL in efficient electron transport.

  2. Development of OPLS-AA Force Field Parameters for 68 Unique Ionic Liquids.

    PubMed

    Sambasivarao, Somisetti V; Acevedo, Orlando

    2009-04-14

    OPLS-AA force field parameters have been developed and validated for use in the simulation of 68 unique combinations of room temperature ionic liquids featuring 1-alkyl-3-methylimidazolium [RMIM] (R = Me, Et, Bu, Hex, Oct), N-alkylpyridinium [RPyr], and choline cations, along with Cl(-), PF6(-), BF4(-), NO3(-), AlCl4(-), Al2Cl7(-), TfO(-), saccharinate, and acesulfamate anions. The new parameters were fit to conformational profiles from gas-phase ab initio calculations at the LMP2/cc-pVTZ(-f)//HF/6-31G(d) theory level and compared to experimental condensed-phase structural and thermodynamic data. Monte Carlo simulations of the ionic liquids gave relative deviations from experimental densities of ca. 1-3% at 25 °C for most combinations and also yielded close agreement over a temperature range of 5 to 90 °C. Predicted heats of vaporization compared well with available experimental data and estimates. Transferability of the new parameters to multiple alkyl side-chain lengths for [RMIM] and [RPyr] was determined to give excellent agreement with charges and torsion potentials developed specific to desired alkyl lengths in 35 separate ionic liquid simulations. As further validation of the newly developed parameters, the Kemp elimination reaction of benzisoxazole via piperidine was computed in 1-butyl-3-methylimidazolium hexafluorophosphate [BMIM][PF6] using mixed quantum and molecular mechanics (QM/MM) simulations and was found to give close agreement with the experimental free energy of activation.

  3. Study on the phase behaviors, viscosities, and thermodynamic properties of CO2/[C(4)mim][PF(6)]/methanol system at elevated pressures.

    PubMed

    Liu, Zhimin; Wu, Weize; Han, Buxing; Dong, Zexuan; Zhao, Guoying; Wang, Jiaqiu; Jiang, Tao; Yang, Guanying

    2003-08-18

    An apparatus to determine the vapor-liquid equilibria of CO(2)/ionic liquid (IL)/organic solvent multisystems and the viscosity of the liquid phase at elevated pressures has been constructed. The solubility of CO(2) in 3-butyl-1-methyl-imidazolium hexafluorophosphate ([C(4)mim][PF(6)]) and the viscosity of CO(2)-saturated [C(4)mim][PF(6)] have been studied at 313.15, 323.15, and 333.15 K and at pressures up to 12.5 MPa. The phase behavior of CO(2)/[C(4)mim][PF(6)]/methanol ternary mixture and the viscosity of the liquid phases at equilibrium condition have also been determined at 313.15 K and at 7.15 and 10.00 MPa. The partition coefficients of the components in the ternary system are calculated. Peng-Robinson equation of state and some thermodynamic functions are combined to calculate the fugacity coefficients of the components in the system. It demonstrates that the viscosity of the IL-rich phase decreases significantly with increasing pressure of CO(2), and the effect of temperature on the viscosity of CO(2)/IL mixture is not noticeable at high pressure, although the viscosity of the CO(2)-free IL decreases dramatically with increasing temperature. Compressed CO(2) may become an attractive reagent for reducing the viscosity of ILs in many applications. The mole fraction of methanol in the CO(2)-rich phase is much lower than that in the IL-rich phase; this indicates that the interaction between the IL and methanol is stronger than that between CO(2) and methanol. The fugacity coefficient of CO(2) in IL-rich phase is larger than unity, while that of methanol is much small than unity, which further suggests that methanol-IL interaction is much stronger than CO(2)-IL interaction. However, the CO(2)-IL interaction is stronger than the CO(2)-methanol interaction.

  4. Ionic Liquid-Induced Unprecedented Size Enhancement of Aggregates within Aqueous Sodium Dodecylbenzene Sulfonate

    SciTech Connect

    Rai, Rewa; Baker, Gary A; Behera, Kamalakanta; Mohanty, Pravakar; Kurur, Narayanan; Pandey, Siddharth

    2010-01-01

    Physicochemical properties of aqueous micellar solutions may change in the presence of ionic liquids (ILs). Micelles help to increase the aqueous solubility of ILs. The average size of the micellar aggregates within aqueous sodium dodecylbenzene sulfonate (SDBS) is observed by dynamic light scattering (DLS) and transmission electron microscopy (TEM) to increase in a sudden and drastic fashion as the IL 1-butyl-3-methylimidazolium hexafluorophosphate ([bmim][PF6]) is added. Similar addition of [bmim][PF6] to aqueous sodium dodecyl sulfate (SDS) results in only a slow gradual increase in average aggregate size. While addition of the IL [bmim][BF4] also gives rise to sudden aggregate size enhancement within aqueous SDBS, the IL 1-ethyl-3-methylimidazolium tetrafluoroborate ([emim][BF4]), and inorganic salts NaPF6 and NaBF4, only gradually increase the assembly size upon their addition. Bulk dynamic viscosity, microviscosity, dipolarity (indicated by the fluorescent reporter pyrene), zeta potential, and electrical conductance measurements were taken to gain insight into this unusual size enhancement. It is proposed that bmim cations of the IL undergo Coulombic attractive interactions with anionic headgroups at the micellar surface at all [bmim][PF6] concentrations in aqueous SDS; in aqueous SDBS, beyond a critical IL concentration, bmim becomes involved in cation- interaction with the phenyl moiety of SDBS within micellar aggregates with the butyl group aligned along the alkyl chain of the surfactant. This relocation of bmim results in an unprecedented size increase in micellar aggregates. Aromaticity of the IL cation alongside the presence of sufficiently aliphatic (butyl or longer) alkyl chains on the IL appear to be essential for this dramatic critical expansion in self-assembly dimensions within aqueous SDBS.

  5. Molecular dynamics study of the effect of alkyl chain length on melting points of [CnMIM][PF6] ionic liquids

    SciTech Connect

    Zhang, Y; Maginn, EJ

    2014-01-01

    Based on molecular dynamics simulations, the melting points T-m of a series of 1-alkyl-3-methylimidazolium hexafluorophosphate ionic liquids [CnMIM][PF6] with n = 2, 4, 10, 12, and 14 were studied using the free energy-based pseudosupercritical path (PSCP) method. The experimental trend that the Tm decreases with increasing alkyl chain length for ILs with short alkyl chains and increases for the ones with long alkyl chains was correctly captured. Further analysis revealed that the different trends are the results of the balance between fusion enthalpy and fusion entropy. For the ILs with short alkyl chains (ethyl and butyl groups), fusion entropy plays the dominant role so that [C4MIM][PF6], which has a larger fusion entropy due to its higher liquid phase entropy has the lower melting temperature. As for the ILs with long alkyl chains, due to the enhanced van der Waals interactions brought about by the long non-polar alkyl chains, enthalpy becomes the deciding factor and the melting points increase when the alkyl chain goes from C10 to C14. While the melting points for [C2MIM][PF6] and [C4MIM][PF6] were quantitatively predicted and the trends for the long chain ILs were captured correctly, the absolute melting points for [C10MIM][PF6], [C12MIM][PF6] and [C14MIM][PF6] were systematically overestimated in the simulations. Three possible reasons for the overestimation were studied but all ruled out. Further simulation or experimental studies are needed to explain the difference.

  6. Temperature controlled ionic liquid-based dispersive micro-extraction using two ligands, for determination of aluminium in scalp hair samples of Alzheimer's patients: A multivariate study

    NASA Astrophysics Data System (ADS)

    Arain, Mariam S.; Arain, Salma A.; Kazi, Tasneem G.; Afridi, Hassan I.; Ali, Jamshaid; Naeemulllah; Arain, Sadaf S.; Brahman, Kapil Dev; Mughal, Moina Akhtar

    2015-02-01

    A green and sensitive temperature controlled dispersive liquid-liquid microextraction (TIL-DLLME) methodology based on the application of ionic liquid 1-butyl-3-methylimidazolium hexafluorophosphate, [C4mim][PF6], as an extractant solvent was proposed for the preconcentration of trace levels of aluminium (Al3+) in scalp hair samples of Alzheimer's (AD) patients, prior to analyzing by flame atomic absorption spectrometry (FAAS). The Al3+ was complexed with 8-hydrooxyquinoline (oxine) (L1) and 3,5,7,2‧-4‧ pentahydroxy flavone (morin) (L2) separately and then extracted by IL at temperature (50 ± 2.0 °C). Some effective factors that influence the TIL-DLLME efficiency such as pH, ligands concentrations, volume of IL, ionic strength, and incubation time were investigated and optimized by multivariate analysis. In the optimum experimental conditions, the limit of detection (3 s) and enhancement factor were 0.56 μg L-1, 0.64 μg L-1 and 85, 73 for both ligands, respectively. The relative standard deviation (RSD) for six replicate determinations of 100 μg L-1 Al3+ complexed with oxine and morin were found to be 3.88% and 4.74%, respectively. The developed method was validated by the analysis of certified reference material of human hair (NCSZC81002).and applied satisfactorily to the determination of Al3+ in acid digested scalp hair samples of AD patients and healthy controls. The resulted data shows significant higher level in scalp hair samples of AD male patients with related to referents of same age and socioeconomic status.

  7. Miniaturized ionic liquid dispersive liquid-liquid microextraction in a coupled-syringe system combined with UV for extraction and determination of danazol in danazol capsule and mice serum

    NASA Astrophysics Data System (ADS)

    Gong, Aiqin; Zhu, Xiashi

    2016-04-01

    In this study, for the first time, a coupled 1-mL microsyringe system was utilized to perform a miniaturized ionic liquid dispersive liquid-liquid microextraction (IL-DLLME) method. Danazol was extracted and determined via the developed method followed by micro-volume ultraviolet spectroscopy (UV). The extraction process was carried out by the injection of extraction solvent ionic liquid 1-octyl-3-methylimidazolium hexafluorophosphate [C8mimPF6] into sample solution (syringe A), and then rapid shoot the solution into syringe B. After that the shooting was repeated several times at a rate of 1 cycle/s. The extraction procedure was induced by the formation of cloudy solution, which was composed of fine drops of [C8mimPF6] dispersed entirely into sample solution with the help of shooting without any dispersive solvent, ultrasonication or high temperature. Several important parameters affecting the extraction efficiency were studied and optimized. Under the optimized conditions, the limit of detection (LOD) was 0.055 μg/mL (capsule) or 0.054 μg/mL (serum) at a signal-to-noise ratio of 3. The calibration curve was linear over the range of 0.62-25 μg/mL. The proposed method was successfully applied to danazol capsule and the real mice serum samples and good spiked recoveries in the range of 90.5-103.4% were obtained. The obtained results of this work were in good agreement with the results of HPLC.

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

    SciTech Connect

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

    2015-03-28

    Molecular dynamics simulations in the NPT ensemble have been carried out to investigate the effect of two room temperature ionic liquids (RTILs), on stacks of phospholipid bilayers in water. We consider RTIL compounds consisting of chloride ([bmim][Cl]) and hexafluorophosphate ([bmim][PF{sub 6}]) salts of the 1-buthyl-3-methylimidazolium ([bmim]{sup +}) cation, while the phospholipid bilayer is made of 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine (POPC). Our investigations focus on structural and dynamical properties of phospholipid and water molecules that could be probed by inelastic and quasi-elastic neutron scattering measurements. The results confirm the fast incorporation of [bmim]{sup +} into the lipid phase already observed in previous simulations, driven by the Coulomb attraction of the cation for the most electronegative oxygens in the POPC head group and by sizeable dispersion forces binding the neutral hydrocarbon tails of [bmim]{sup +} and of POPC. The [bmim]{sup +} absorption into the bilayer favours the penetration of water into POPC, causes a slight but systematic thinning of the bilayer, and further stabilises hydrogen bonds at the lipid/water interface that already in pure samples (no RTIL) display a lifetime much longer than in bulk water. On the other hand, the effect of RTILs on the diffusion constant of POPC (D{sub POPC}) does not reveal a clearly identifiable trend, since D{sub POPC} increases upon addition of [bmim][Cl] and decreases in the [bmim][PF{sub 6}] case. Moreover, because of screening, the electrostatic signature of each bilayer is only moderately affected by the addition of RTIL ions in solution. The analysis of long wavelength fluctuations of the bilayers shows that RTIL sorption causes a general decrease of the lipid/water interfacial tension and bending rigidity, pointing to the destabilizing effect of RTILs on lipid bilayers.

  9. Importance of dispersion forces for prediction of thermodynamic and transport properties of some common ionic liquids.

    PubMed

    Izgorodina, Ekaterina I; Golze, Dorothea; Maganti, Radha; Armel, Vanessa; Taige, Maria; Schubert, Thomas J S; MacFarlane, Douglas R

    2014-04-28

    An extensive study of interaction energies in ion pairs of pyrrolidinium and imidazolium ionic liquids is presented. The Cnmpyr and Cnmim cations with varying alkyl chains from Methyl, Ethyl, n-Propyl to n-Butyl were combined with a wide range of routinely used IL anions such as chloride, bromide, mesylate (CH3SO3 or Mes), tosylate (CH3PhSO3 or Tos), bis(trifluoromethanesulfonyl)amide (NTf2), dicyanamide (N(CN)2 or dca), tetrafluoroborate (BF4) and hexafluorophosphate (PF6). A number of energetically favourable conformations were studied for each cation-anion combination. The interaction energy and its dispersion component of the single ion pairs were calculated using a sophisticated state-of-the-art approach: a second-order of Symmetry Adapted Perturbation Theory (SAPT). A comparison of energetics depending on the cation-anion type, as well as the mode of interaction was performed. Dispersion forces were confirmed to be of importance for the overall stabilisation of ionic liquids contributing from 28 kJ mol(-1) in pyrrolidinium ion pairs to 59 kJ mol(-1) in imidazolium ion pairs. The previously proposed ratio of total interaction energy to dispersion components and melting points was assessed for this set of ionic liquids and was found to correlate with their melting points for the anionic series, producing separate trends for the Cnmim and Cmpyr series of cations. Chlorides, bromides and tetrafluoroborates formed close-to-ideal correlations when both types of cations, Cnmim and Cnmpyr, were combined in the same trend. Correlation of the dispersion component of the interaction energy with transport properties such as conductivity and viscosity was also considered. For imidazolium-based ionic liquids strong linear correlations were obtained, whereas pyrrolidinium ionic liquids appeared to be insensitive to this correlation.

  10. Second sphere coordination in binding of fluoroanions: Synthesis, spectroscopic characterization and single crystal X-ray structure determination of [Co(phen) 3](BF 4) 3·H 2O and [Co(phen) 3](PF 6) 3·CH 3COCH 3

    NASA Astrophysics Data System (ADS)

    Sharma, Raj Pal; Singh, Ajnesh; Brandão, Paula; Felix, Vitor; Venugopalan, Paloth

    2009-02-01

    In an effort to capture fluoroanions by cationic cobalt(III) complex, two new cobalt(III) complex salts of composition [Co(phen) 3](BF 4) 3·H 2O ( 1) and [Co(phen) 3](PF 6) 3·CH 3COCH 3 ( 2) have been synthesized by the reaction of tris(1,10-phenanthroline)cobalt(III)chloride with sodium salts of tetrafluorborate and hexafluorophosphate (1:3 molar ratio) in aqueous medium. Single crystals of 1 were obtained directly from the reaction mixture when the solution was allowed to evaporate slowly at room temperature and single crystals of 2 were obtained by recrystallizing the precipitated product from acetone and water solution by slow evaporation. The newly synthesized complex salts were characterized by elemental analyses, TGA spectroscopic studies (IR, UV/Visible, 1H, 13C, 19F and 11B NMR), solubility product and conductance measurements. X-ray structure determination revealed ionic structures consisting of one [Co(phen) 3] 3+, three [BF 4] - ions and one lattice water molecule in complex salt 1, one [Co(phen) 3] 3+, three [PF 6] - anions and one acetone molecule as solvent of crystallization in complex salt 2. The three 1,10-phenanthroline ligands (each bidentate) coordinated to cobalt(III) showed distorted octahedral geometry around the central metal ion. Supramolecular hydrogen bonding networks between ionic groups [Co-phenCH δ+⋯ Fanionδ-] by second sphere coordination have been observed that stabilize crystal lattice besides electrostatic forces of attraction. The structural studies suggest that [Co(phen) 3] 3+ is a promising anion receptor for the fluoroanions (BF 4) - and (PF 6) -in aqueous medium.

  11. Fabrication of gallium hexacyanoferrate modified carbon ionic liquid paste electrode for sensitive determination of hydrogen peroxide and glucose.

    PubMed

    Haghighi, Behzad; Khosravi, Mehdi; Barati, Ali

    2014-07-01

    Gallium hexacyanoferrate (GaHCFe) and graphite powder were homogeneously dispersed into n-dodecylpyridinium hexafluorophosphate and paraffin to fabricate GaHCFe modified carbon ionic liquid paste electrode (CILPE). Mixture experimental design was employed to optimize the fabrication of GaHCFe modified CILPE (GaHCFe-CILPE). A pair of well-defined redox peaks due to the redox reaction of GaHCFe through one-electron process was observed for the fabricated electrode. The fabricated GaHCFe-CILPE exhibited good electrocatalytic activity towards reduction and oxidation of H2O2. The observed sensitivities for the electrocatalytic oxidation and reduction of H2O2 at the operating potentials of +0.8 and -0.2V were about 13.8 and 18.3 mA M(-1), respectively. The detection limit (S/N=3) for H2O2 was about 1 μM. Additionally, glucose oxidase (GOx) was immobilized on GaHCFe-CILPE using two methodology, entrapment into Nafion matrix and cross-linking with glutaraldehyde and bovine serum albumin, in order to fabricate glucose biosensor. Linear dynamic rage, sensitivity and detection limit for glucose obtained by the biosensor fabricated using cross-linking methodology were 0.1-6mM, 0.87 mA M(-1) and 30 μM, respectively and better than those obtained (0.2-6mM, 0.12 mA M(-1) and 50 μM) for the biosensor fabricated using entrapment methodology.

  12. Ionic liquid templated porous nano-TiO2 particles for the selective isolation of cytochrome c

    NASA Astrophysics Data System (ADS)

    Meng, Hao; Chen, Xu-Wei; Wang, Jian-Hua

    2010-09-01

    Porous nano-titanium dioxide (TiO2) particles with anatase framework were prepared by using an effective template of hydrophobic ionic liquid, i.e., N, N-bis [2-methylbutyl] imidazolium hexafluorophosphate ([PPim][PF6]). The nano-TiO2 particles were characterized with TEM and BET, resulting in the distribution of the pore diameters centering at 7.3 nm and 26.2 nm, attributed to the template effect of the ionic liquid and the aggregation of the TiO2 particles, respectively. A much improved surface area of 68.31 m2 g - 1 and a pore volume of 0.2814 cm3 g - 1 were obtained with respect to 15.16 m2 g - 1 and 0.0402 cm3 g - 1 achieved by the non-templated nano-TiO2 counterpart. The porous nano-TiO2 particles were used as adsorbent for selective adsorption and isolation of cytochrome c (cyt-c) at certain conditions. An adsorption efficiency of 87% was achieved for 150 µg ml - 1 cyt-c in 1.0 ml of sample solution at pH 9.0 by using 2.0 mg of the nano-TiO2 particles, in comparison to 30% obtained by the non-templated nano-TiO2. In addition, an adsorption capacity of 112.6 µg mg - 1 was derived for the porous nano-TiO2 with respect to 25.1 µg mg - 1 for the normal ones. The absorbed cyt-c could be readily recovered by stripping with a 0.1 mol l - 1 Na3PO4 solution, giving rise to a recovery of ca. 90%. The porous nano-TiO2 particles have been used for the isolation of cyt-c from human whole blood, achieving satisfactory results by assay with SDS-PAGE.

  13. Nuclear magnetic resonance study on rotational dynamics of water and benzene in a series of ionic liquids: Anion and cation effects

    NASA Astrophysics Data System (ADS)

    Kimura, Hiroshi; Yasaka, Yoshiro; Nakahara, Masaru; Matubayasi, Nobuyuki

    2012-11-01

    The rotational correlation times (τ2R) for polar water (D2O) molecule and apolar benzene (C6D6) molecule were determined in ionic liquids (ILs) by means of the 2H (D) NMR spin-lattice relaxation time (T1) measurements. The solvent IL was systematically varied to elucidate the anion and cation effects separately. Five species, bis(trifluoromethylsulfonyl)imide (TFSI-), trifluoromethylsulfonate (TfO-), hexafluorophosphate (PF6-), chloride (Cl-), and formate (HCOO-), were examined for the anion effect against a fixed cation species of 1-butyl-3-methyl-imidazolium (bmim+). Four species, bmim+, N-methyl-N-butylpyrrolidinium (bmpy+), N,N,N-trimethyl-N-propylammonium (N1,1,1,3+), and P,P,P-trihexyl-P-tetradecylphosphonium (P6,6,6,14+), were employed for the cation effect against a fixed anion species of TFSI-. The τ2R ratio of water to benzene, expressed as τW/B, was used as a probe to characterize the strength of Coulombic solute-solvent interaction in ILs beyond the hydrodynamic limit based on the excluded-volume effect. The τW/B value was found to strongly depend on the anion species, and the solute dynamics are sensitive not only to the size but also to the chemical structure of the component anion. The cation effect was rather weak, in contrast. The largest and most hydrophobic P6,6,6,14+ cation was exceptional and a large τW/B was observed, indicating a unique solvation structure in [P6,6,6,14+]-based ILs.

  14. Ionic-liquid-based dispersive liquid-liquid microextraction combined with magnetic solid-phase extraction for the determination of aflatoxins B1 , B2 , G1 , and G2 in animal feeds by high-performance liquid chromatography with fluorescence detection.

    PubMed

    Zhao, Jiao; Zhu, Yan; Jiao, Yang; Ning, Jinyan; Yang, Yaling

    2016-10-01

    A novel two-step extraction technique combining ionic-liquid-based dispersive liquid-liquid microextraction with magnetic solid-phase extraction was developed for the preconcentration and separation of aflatoxins in animal feedstuffs before high-performance liquid chromatography coupled with fluorescence detection. In this work, ionic liquid 1-octyl-3-methylimidazolium hexafluorophosphate was used as the extractant in dispersive liquid-liquid microextraction, and hydrophobic pelargonic acid modified Fe3 O4 magnetic nanoparticles as an efficient adsorbent were applied to retrieve the aflatoxins-containing ionic liquid. Notably, the target of magnetic nanoparticles was the ionic liquid rather than the aflatoxins. Because of the rapid mass transfer associated with the dispersive liquid-liquid microextraction and magnetic solid phase steps, fast extraction could be achieved. The main parameters affecting the extraction recoveries of aflatoxins were investigated and optimized. Under the optimum conditions, vortexing at 2500 rpm for 1 min in the dispersive liquid-liquid microextraction and magnetic solid-phase extraction and then desorption by sonication for 2 min with acetonitrile as eluent. The recoveries were 90.3-103.7% with relative standard deviations of 3.2-6.4%. Good linearity was observed with correlation coefficients ranged from 0.9986 to 0.9995. The detection limits were 0.632, 0.087, 0.422 and 0.146 ng/mL for aflatoxins B1 , B2, G1, and G2, respectively. The results were also compared with the pretreatment method carried out by conventional immunoaffinity columns.

  15. Stokes shift dynamics in (ionic liquid + polar solvent) binary mixtures: composition dependence.

    PubMed

    Daschakraborty, Snehasis; Ranjit, Biswas

    2011-04-14

    An approximate semimolecular theory has been developed to investigate the composition dependence of Stokes shift dynamics of a fluorescent dye molecule dissolved in binary mixtures of an ionic liquid (IL) with a conventional polar solvent at different mole fractions. The theory expresses the dynamic Stokes shift as a sum of contributions from the dye-IL and the dye-polar solvent interactions and suggests substantial solute-cation dipole-dipole interaction contribution to the solvation energy relaxation. The theory, when applied to aqueous mixtures of 1-butyl-3-methylimidazolium hexafluorophosphate ([Bmim][PF(6)]) and tetrafluoroborate ([Bmim][BF(4)]), and binary mixtures of ([Bmim][BF(4)] + acetonitrile), predicts reduction of Stokes shift but acceleration of the dynamics upon increasing the polar solvent concentration for the most part of the mixture composition. The decrease in dynamic Stokes shift values has been found to occur due to decrease of the dye-IL interaction in the presence of the added polar solvent. For aqueous binary mixtures of IL, the predicted results are in semiquantitative agreement with the available experimental results. However, the calculated dynamics suggest much weaker composition dependence than that observed in experiments. In addition, the theory predicts a turn around for dynamic Stokes shift in its composition dependence for ([Bmim][BF(4)] + acetonitrile) mixtures at higher dilutions of the IL. Interestingly, effective dipolar medium calculations for Stokes shift dynamics in ([Bmim][BF(4)] + dichloromethane) binary mixtures predict a very weak or even nonexistent nonlinear composition dependence. These predictions should be reexamined in experiments.

  16. Effect of the physicochemical properties of binary ionic liquids on lipase activity and stability.

    PubMed

    Yao, Peipei; Yu, Xinxin; Huang, Xirong

    2015-01-01

    In the present study, the lipase-catalyzed hydrolysis of p-nitrophenyl butyrate is used as a model reaction to determine the activity and stability of Candida rugosa lipase in binary ionic liquids (ILs). The binary ILs consist of hydrophobic 1-butyl-3-methylimidazolium hexafluorophosphate ([Bmim]PF6) and a small amount of hydrophilic 1-butyl-3-methylimidazolium nitrate ([Bmim]NO3) or 1-butyl-3-methylimidazolium trifluoromethanesulfonate ([Bmim]CF3SO3) or 1-butyl-3-methylimidazolium tetrafluoroborate ([Bmim]BF4). The activity and the stability of lipase are first correlated with the physicochemical properties of the binary ILs. In the three binary IL systems, both the hydrophilicity and the polarity of the systems increase with the increase of the content of hydrophilic ILs (HILs). At a fixed concentration of HIL, they vary in a descending order of [Bmim]PF6/[Bmim]NO3>[Bmim]PF6/[Bmim]CF3SO3>[Bmim]PF6/[Bmim]BF4. This order is in contrast with the order of the lipase conformation stability, i.e., the higher the polarity of ILs, the more unstable the lipase conformation. However, both the activity and the stability of lipase depend on the type and the content of the HIL in binary ILs, showing a complex dependency. Analysis shows that the catalytic performance of lipase in the binary ILs is affected not only by the direct influence of the ILs on lipase conformation, but also through their indirect influence on the physicochemical properties of water. The present study helps to explore binary IL mixtures suitable for lipase-based biocatalysis.

  17. Solvation of uranyl-CMPO complexes in dry vs. humid forms of the [BMI][PF6] ionic liquid. A molecular dynamics study.

    PubMed

    Chaumont, Alain; Wipff, Georges

    2006-01-28

    The solvation of the [UO(2)(NO(3))(CMPO)](+) and [UO(2)(NO(3))(2)(CMPO)(2)] complexes (CMPO = octyl(phenyl)-N,N-diisobutylmethylcarbamoyl phosphine oxide) is investigated by molecular dynamics in the "dry" and "humid" forms of a room temperature ionic liquid (IL) based on the 1-butyl-3-methylimidazolium (BMI(+)) cation and the hexafluorophosphate (PF(6)(-)) anion. The simulations reveal the importance of the solvent anions in "dry" conditions and of water molecules in the "humid" solvent. For the [UO(2)(NO(3))(CMPO)](+) complex, the monodentate vs. bidentate coordination modes of CMPO are compared, and the first solvation shell of uranyl is completed by 1-3 PF(6)(-) anions in the dry IL and by 2-3 water molecules in the humid IL, leading to a total coordination number close to 5. The energy analysis shows that interactions with the IL stabilize the [UO(2)(NO(3))(bi)(CMPO)(mono)](+) form (with bidentate nitrate and monodentate CMPO) in the dry IL and the [UO(2)(NO(3))(mono)(CMPO)(mono)](+) form (with monodentate nitrate and CMPO) in the humid IL. The extracted compound characterized by EXAFS is thus proposed to be the [UO(2)(NO(3))(mono)(CMPO)(mono)(H(2)O)(3)](+) species. Furthermore we compare the [UO(2)(NO(3))(2)(CMPO)(2)] complex in its associated and dissociated forms ([UO(2)(NO(3))(mono)(CMPO)(mono)](+) + CMPO + NO(3)(-)) and discuss the results in the context of uranyl extraction by CMPO to ionic liquids.

  18. PVC membrane based potentiometric sensors for uranium determination.

    PubMed

    Hassan, S S; Ali, M M; Attawiya, A M

    2001-07-06

    Two novel uranyl PVC matrix membrane sensors responsive to uranyl ion are described. The first sensor incorporates tris(2-ethylhexyl)phosphate (TEHP) as both electroactive material and plasticizer and sodium tetraphenylborate (NaTPB) as an ion discriminator. The sensor displays a rapid and linear response for UO(2)(2+) ions over the concentration range 1x10(-1)-2x10(-5) mol l(-1) UO(2)(2+) with a cationic slope of 25.0+/-0.2 mV decade(-1). The working pH range is 2.8-3.6 and the life span is 4 weeks. The second sensor contains O-(1,2-dihydro-2-oxo-1-pyridyl)-N,N,N',N'-bis(tetra-methylene)uronium hexafluorophosphate (TPTU) as a sensing material, sodium tetraphenylborate as an ion discriminator and dioctyl phenylphosphonate (DOPP) as a plasticizer. Linear and stable response for 1x10(-1)-5x10(-5) mol l(-1) UO(2)(2+) with near-Nernstian slope of 27.5+/-0.2 mV decade(-1) are obtained. The working pH range is 2.5-3.5 and the life span of the sensor is 6 weeks. Interference from many inorganic cations is negligible for both sensors. However, interference caused by some ions (e.g. Th(4+), Cu(2+), Fe(3+)) is eliminated by a prior ion exchange or solvent extraction step. Direct potentiometric determination of as little as 5 mug ml(-1) uranium in aqueous solutions shows an average recovery of 97.2+/-1.3%. Application for the determination of uranium at levels of 0.01-1 wt.% in naturally occurring and certified ores gives results with good correlation with data obtained by X-ray fluorescence.

  19. Toxicity of ionic liquids to Clostridium sp. and effects on uranium biosorption.

    PubMed

    Zhang, C; Malhotra, S V; Francis, A J

    2014-01-15

    As green solvents ionic liquids (ILs) show high potential in nuclear industry for extraction and purification of actinides. However, to date relatively little information has been gained on ILs application in microbial processes, for example biosorption of radionuclides. We investigated the effects of three ILs, 1-butyl-3-methylimidazolium hexafluorophosphate (BMIMPF6), N-ethylpyridinium trifluoroacetate (EtPyCF3COO) and N-ethylpyridinium tetrafluoroborate (EtPyBF4) on the growth and biosorption of uranium by Clostridium sp. The ILs affected the growth of the bacterium as evidenced by decreases in optical density, total gas production, and organic acids production from glucose metabolism. The IC50-48h of three ILs decreased in the order of BMIMPF6 (8.26mM)>EtPyBF4 (7.04mM)>EtPyCF3COO (4.05mM). Uranium biosorption by the bacterial cells decreased by 75% in the presence of 1% (v/v) BMIMPF6 and by about 90% with 1% (v/v) EtPyBF4 or EtPyCF3COO, in comparison to the control without ILs. The diminished biosorption may be attributed to the membrane damages induced by EtPyBF4 and EtPyCF3COO, which can be visualized by Transmission Electron Microscope (TEM) analysis. Energy-dispersive X-ray spectroscopy (EDS) analysis revealed the accumulation of uranium inside peripheral membrane of the cells exposed to uranium alone or with BMIMPF6, while little or no accumulation was observed in the presence of EtPyBF4 and EtPyCF3COO. These results imply that potential toxicity of ILs towards microorganisms is a particularly important issue in limiting its biotechnological applications.

  20. Optimized syntheses of Fmoc azido amino acids for the preparation of azidopeptides.

    PubMed

    Pícha, Jan; Buděšínský, Miloš; Macháčková, Kateřina; Collinsová, Michaela; Jiráček, Jiří

    2017-03-01

    The rise of CuI-catalyzed click chemistry has initiated an increased demand for azido and alkyne derivatives of amino acid as precursors for the synthesis of clicked peptides. However, the use of azido and alkyne amino acids in peptide chemistry is complicated by their high cost. For this reason, we investigated the possibility of the in-house preparation of a set of five Fmoc azido amino acids: β-azido l-alanine and d-alanine, γ-azido l-homoalanine, δ-azido l-ornithine and ω-azido l-lysine. We investigated several reaction pathways described in the literature, suggested several improvements and proposed several alternative routes for the synthesis of these compounds in high purity. Here, we demonstrate that multigram quantities of these Fmoc azido amino acids can be prepared within a week or two and at user-friendly costs. We also incorporated these azido amino acids into several model tripeptides, and we observed the formation of a new elimination product of the azido moiety upon conditions of prolonged couplings with 2-(1H-benzotriazol-1-yl)-1,1,3,3-tetramethyluronium hexafluorophosphate/DIPEA. We hope that our detailed synthetic protocols will inspire some peptide chemists to prepare these Fmoc azido acids in their laboratories and will assist them in avoiding the too extensive costs of azidopeptide syntheses. Experimental procedures and/or analytical data for compounds 3-5, 20, 25, 26, 30 and 43-47 are provided in the supporting information. © 2017 The Authors Journal of Peptide Science published by European Peptide Society and John Wiley & Sons Ltd.

  1. Dynamics of Loop 1 of Domain I in Human Serum Albumin WhenDissolved in Ionic Liquids

    SciTech Connect

    Page, Taylor; Kraut, Nadine; Page, Phillip; Baker, Gary A; Bright, Frank

    2009-01-01

    We report on the rotational reorientation dynamics associated with loop 1 of domain I within a large multidomain protein (human serum albumin, HSA) when it is dissolved in binary mixtures of ionic liquid (1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ([C4mim][Tf2N]), 1-butyl-3-methylimidazolium tetrafluoroborate ([C4mim][BF4]), or 1-butyl-3-methylimidazolium hexafluorophosphate ([C4mim][PF6])) and distilled deionized water (ddH2O) as a function of temperature and water loading. In IL/2% ddH2O (v/v) mixtures, loop 1 of domain I is more significantly denatured in comparison to the protein dissolved in aqueous solutions containing strong chemical denaturants (e.g., 8 M guanidine HCl (Gu HCl) or urea). As water loading increases, there is evidence for progressive refolding of loop 1 of domain I followed by recoupling with domains I, II, and III in the [C4mim][BF4]/ddH2O mixtures at 20 C. Above 30% (v/v) water, where domain I appears refolded, the Ac reporter molecule s semiangle steadily decreases from 35 to 20 with increasing water loading. From the perspective of domain I in HSA, this behavior is similar to the effects of dilution from 4 to 0 M Gu HCl in aqueous solution. Overall, these results lend insight into the tangle of biocatalytic and structural/dynamical mechanisms that enzymes may undergo in ionic liquid-based systems. It will be particularly motivating to extend this work to include enzyme-attuned ionic liquids shown to improve biocatalytic performance beyond that possible in the native (predominantly aqueous) setting.

  2. Ion yields for some salts in MALDI: mechanism for the gas-phase ion formation from preformed ions.

    PubMed

    Moon, Jeong Hee; Shin, Young Sik; Bae, Yong Jin; Kim, Myung Soo

    2012-01-01

    Preformed ion emission is the main assumption in one of the prevailing theories for peptide and protein ion formation in matrix-assisted laser desorption ionization (MALDI). Since salts are in preformed ion forms in the matrix-analyte mixture, they are ideal systems to study the characteristics of preformed ion emission. In this work, a reliable method to measure the ion yield (IY) in MALDI was developed and used for a solid salt benzyltriphenylphosphonium chloride and two room-temperature ionic liquids 1-butyl-3-methylimidazolium hexafluorophosphate and trihexyltetradecylphosphonium bis(2,4,4-trimethylpentyl)phosphinate. IY for the matrix (α-cyano-4-hydroxycinnamic acid, CHCA) was also measured. Taking 1 pmol salts in 25 nmol CHCA as examples, IYs for three salts were similar, (4-8) × 10(-4), and those for CHCA were (0.8-1.2) × 10(-7). Even though IYs for the salts and CHCA remained virtually constant at low analyte concentration, they decreased as the salt concentrations increased. Two models, Model 1 and Model 2, were proposed to explain low IYs for the salts and the concentration dependences. Both models are based on the fact that the ion-pair formation equilibrium is highly shifted toward the neutral ion pair. In Model 1, the gas-phase analyte cations were proposed to originate from the same cations in the solid that were dielectrically screened from counter anions by matrix neutrals. In Model 2, preformed ions were assumed to be released from the solid sample in the form of neutral ion pairs and the anions in the ion pairs were assumed to be eliminated via reactions with matrix-derived cations.

  3. Mesoscopic simulation of a micellar poly(N-isopropyl acrylamide)-b-(polyethylene oxide) copolymer system

    NASA Astrophysics Data System (ADS)

    Bautista-Reyes, Rubén; Soto-Figueroa, César; Vicente, Luis

    2016-05-01

    In this article we studied the micellar formation of poly(N-isopropyl acrylamide)-b-polyethylene oxide (PNIPAM-b-PEO) copolymers in an aqueous system. From molecular simulations the dependence on temperature of the Flory-Huggins interaction parameter χ for PNIPAM and PEO in water is obtained and compared with available experimental results and values from other theoretical calculations. By means of dissipative particle dynamics (DPD) we then simulated the coil-globule transition for PNIPAM chains in water with a transition temperature of around 305 K. The simulations for PNIPAM-b-PEO copolymers showed that at room temperature the chains are miscible in an aqueous phase but with a temperature increase the system turns into micelles at T  =  305 K. The change in micelle anisotropy due to a different ratio PNIPAM/PEO of chains is also analyzed. What is observed is that for large PEO the large number of dissolved PEO chains gives a large corona size and the micelle is not spherical but obloide and as the number of PNIPAM is increased the micelle acquires a spherical shape. As an important application we considered the system micelle-water/anionic liquid (1-butyl-3-methylimidazolium hexafluorophosphate [BMIM]+[PF6]-). By increasing the temperature of the system from 306 K it is shown that at T  =  345 K there is a transfer of the micelle from water to the ionic liquid phase and this was due to the change in the relative affinity of PEO to water and ionic liquid expressed by the change in χ. All the simulation outcomes are qualitatively consistent with experimental results and thus to our knowledge we give the first set of χ values for the interaction between PNIPAM and water in a wide range of temperature values.

  4. Rapid ionic liquid-based ultrasound assisted dual magnetic microextraction to preconcentrate and separate cadmium-4-(2-thiazolylazo)-resorcinol complex from environmental and biological samples.

    PubMed

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

    2014-04-05

    A rapid and innovative microextraction technique named as, ionic liquid-based ultrasound-assisted dual magnetic microextraction (IL-UA-DMME) was developed for the preconcentration and extraction of trace cadmium from environmental and biological samples, prior to analyzed by flame atomic absorption spectrometry (FAAS). The proposed method has many obvious advantages, including evading the use of organic solvents and achieved high extraction yields by the combination of dispersive liquid-liquid microextraction (DLLME) and magnetic mediated-solid phase extraction (MM-SPE). In this approach ionic liquid (IL) 1-butyl-3-methylimidazolium hexafluorophosphate [C4mim][PF6] play an important role to extract the cadmium-4-(2-thiazolylazo)-resorcinol (Cd-TAR) complex from acid digested sample solutions and ultrasonic irradiation was applied to assist emulsification. After then, dispersed small amount of Fe3O4 magnetic nanoparticles (MNPs) in sample solutions to salvaged the IL and complete phase separation was attained. Some analytical parameters that influencing the efficiency of proposed (IL-UA-DMME) method, such as pH, volume of IL, ligand concentration, ultra-sonication time, amount of Fe3O4 MNPs, sample volume and matrix effect were optimized. Limit of detection (LOD) and enrichment factor (EF) of the method under optimal experimental conditions were found to be 0.40μgL(-1) and 100, respectively. The relative standard deviation (RSD) of 50μgL(-1) Cd was 4.29%. The validity and accuracy of proposed method, was assessed to analyzed certified reference materials of fortified lake water TMDA-54.4, SPS-WW2 waste water, spinach leaves 1570a and also checked by standard addition method. The obtained values showed good agreement with the certified values and sufficiently high recovery were found in the range of 98.1-101% for Cd. The proposed method was facile, rapid and successfully applied for the determination of Cd in environmental and different biological samples.

  5. Etched colloidal LiFePO4 nanoplatelets toward high-rate capable Li-ion battery electrodes.

    PubMed

    Paolella, Andrea; Bertoni, Giovanni; Marras, Sergio; Dilena, Enrico; Colombo, Massimo; Prato, Mirko; Riedinger, Andreas; Povia, Mauro; Ansaldo, Alberto; Zaghib, Karim; Manna, Liberato; George, Chandramohan

    2014-12-10

    LiFePO4 has been intensively investigated as a cathode material in Li-ion batteries, as it can in principle enable the development of high power electrodes. LiFePO4, on the other hand, is inherently "plagued" by poor electronic and ionic conductivity. While the problems with low electron conductivity are partially solved by carbon coating and further by doping or by downsizing the active particles to nanoscale dimensions, poor ionic conductivity is still an issue. To develop colloidally synthesized LiFePO4 nanocrystals (NCs) optimized for high rate applications, we propose here a surface treatment of the NCs. The particles as delivered from the synthesis have a surface passivated with long chain organic surfactants, and therefore can be dispersed only in aprotic solvents such as chloroform or toluene. Glucose that is commonly used as carbon source for carbon-coating procedure is not soluble in these solvents, but it can be dissolved in water. In order to make the NCs hydrophilic, we treated them with lithium hexafluorophosphate (LiPF6), which removes the surfactant ligand shell while preserving the structural and morphological properties of the NCs. Only a roughening of the edges of NCs was observed due to a partial etching of their surface. Electrodes prepared from these platelet NCs (after carbon coating) delivered a capacity of ∼ 155 mAh/g, ∼ 135 mAh/g, and ∼ 125 mAh/g, at 1 C, 5 C, and 10 C, respectively, with significant capacity retention and remarkable rate capability. For example, at 61 C (10.3 A/g), a capacity of ∼ 70 mAh/g was obtained, and at 122 C (20.7 A/g), the capacity was ∼ 30 mAh/g. The rate capability and the ease of scalability in the preparation of these surface-treated nanoplatelets make them highly suitable as electrodes in Li-ion batteries.

  6. Influence of the organization of water-in-ionic liquid microemulsions on the size of silver particles during photoreduction.

    PubMed

    Harada, Masafumi; Yamada, Masako; Kimura, Yoshifumi; Saijo, Kenji

    2013-09-15

    Metal particles of silver (Ag) have been synthesized by the photoreduction of silver nitrate (AgNO3) in water-in-ionic liquid (IL) microemulsions consisting of nonionic surfactant Tween 20 or Triton X-100, water and ionic liquid, 1-octyl-3-methylimidazolium hexafluorophosphate ([OMIm][PF6]). The formation of microemulsions as well as Ag particles produced by the photoreduction has been investigated by UV-vis, cryo-TEM, small-angle X-ray scattering (SAXS), and extended X-ray absorption fine structure (EXAFS) measurements. At the early stage of Ag particle formation under ambient pressure, the size of Ag particles in water/[OMIm][PF6]/TX-100 microemulsions was slightly larger than that in water/[OMIm][PF6]/Tween20 microemulsions. With an increase in photoirradiation time beyond 30 min, precipitation of larger Ag aggregates occurred. In contrast to the preparation under ambient pressure, the growth of Ag particles and aggregates was suppressed in preparing under high pressure (25 MPa) of CO2, leading to no precipitation of Ag aggregates. The average diameters of the finally-obtained metallic Ag particles prepared under high pressure of CO2 in water/[OMIm][PF6]/Tween20 and water/[OMIm][PF6]/TX-100 microemulsions were estimated from cryo-TEM to be 3.7 nm and 2.8 nm, respectively. By using Guinier plots at q (<0.16 nm(-1)), it was demonstrated that the diameter of the water droplets during Ag particle formation under high pressure of CO2 remained unchanged in the range of 33-37 nm due to their higher stability compared to water droplets, whereas under ambient pressure the diameter drastically increases from 28 nm to 40 nm during the first 60 min of photoirradiation, resulting in the precipitation of larger Ag aggregates, especially in the case of water/[OMIm][PF6]/Tween20 microemulsions.

  7. Non-covalent interactions in ionic liquid ion pairs and ion pair dimers: a quantum chemical calculation analysis.

    PubMed

    Marekha, Bogdan A; Kalugin, Oleg N; Idrissi, Abdenacer

    2015-07-14

    Ionic liquids (ILs) being composed of bulky multiatomic ions reveal a plethora of non-covalent interactions which determine their microscopic structure. In order to establish the main peculiarities of these interactions in an IL-environment, we have performed quantum chemical calculations for a set of representative model molecular clusters. These calculations were coupled with advanced methods of analysis of the electron density distribution, namely, the quantum theory of atoms in molecules (QTAIM) and the non-covalent interaction (NCI; J. Am. Chem. Soc., 2010, 132, 6499) approaches. The former allows for profound quantitative characterization of non-covalent interactions between atoms while the latter gives an overview of spatial extent, delocalization, and relative strength of such interactions. The studied systems consist of 1-butyl-3-methylimidazolium (Bmim(+)) cations and different perfluorinated anions: tetrafluoroborate (BF4(-)), hexafluorophosphate (PF6(-)), trifluoromethanesulfonate (TfO(-)), and bis(trifluoromethanesulfonyl)imide (TFSI(-)). IL ion pairs and ion pair dimers were considered as model structures for the neat ILs and large aggregates. Weak electrostatic hydrogen bonding was found between the anions and the imidazolium ring hydrogen atoms of cations. Weaker but still appreciable hydrogen bonding was also noted for hydrogen atoms adjacent to the imidazolium ring alkyl groups of Bmim(+). The relative strength of the hydrogen bonding is higher in BmimTfO and BmimBF4 ILs than in BmimPF6 and BmimTFSI, whereas BmimTfO and BmimTFSI reveal higher sensitivity of hydrogen bonding at the different hydrogen atoms of the imidazolium ring.

  8. Protein/ionic liquid/glassy carbon sensors following analyte focusing by ionic liquid micelle collapse for simultaneous determination of water soluble vitamins in plasma matrices.

    PubMed

    Abd El-Hady, D; Albishri, H M

    2015-07-01

    Two novel sensors based on human serum albumin (HSA)-ionic liquid (IL) and bovine serum albumin (BSA)-ionic liquid (IL) composites modified glassy carbon electrode (GCE) were produced for simultaneous determination of water soluble vitamins B2, B6 and C in human plasma following analytes focusing by IL micelles collapse (AFILMC). For selective and efficient extraction, vitamins were dissolved in 3.0molL(-1) micellar solution of 1-octyl-3-methyl imidazolium bromide IL. The extracted vitamins were hydrodynamically injected by 25mbar for 20s into a running buffer of 12.5mmolL(-1) phosphate at pH 6.0 followed by electrochemical detection (ECD) on protein/1-octyl-3-methyl imidazolium hexafluorophosphate IL/GC sensors. The chemical stability of proposed sensors was achieved up to 7 days without any decomposition of PF6-based IL/protein and adsorption of interfering ions. In the current work, the sensitivity enhancement factor (SEF) up to 5000-fold was achieved using the AFILMC/ECD setup compared to conventional CE/UV. Under optimal conditions, linear calibration graphs were obtained from 0.5, 0.5 and 1.0 to 1500.0µgmL(-1) of vitamins B2, B6 and C, respectively. Detection limits of analytes were ranged from 180.0 to 520.0ngmL(-1). The proposed AFILMC/ECD setup was successfully applied to the assay of trace level quantification of vitamins in human plasma samples and also their binding constants with HSA and BSA were determined. The concurrent use of IL micelles for the proposed separation and detection processes exhibited some advantages, such as, a reduction of use toxic solvents, an efficient extraction and a direct injection of samples with a short-single run. Furthermore, IL micelles, having variable possibility of interactions, facilitated the successful achievements of AFILMC/ECD setup for the quantification of vitamins in plasma matrices.

  9. Anion induced formation of supramolecular associations involving lone pair-π and anion-π interactions in Co(II) malonate complexes: experimental observations, Hirshfeld surface analyses and DFT studies.

    PubMed

    Manna, Prankrishna; Seth, Saikat Kumar; Das, Amrita; Hemming, Joanna; Prendergast, Richard; Helliwell, Madeleine; Choudhury, Somnath Ray; Frontera, Antonio; Mukhopadhyay, Subrata

    2012-03-19

    Three Co(II)-malonate complexes, namely, (C(5)H(7)N(2))(4)[Co(C(3)H(2)O(4))(2)(H(2)O)(2)](NO(3))(2) (1), (C(5)H(7)N(2))(4)[Co(C(3)H(2)O(4))(2)(H(2)O)(2)](ClO(4))(2) (2), and (C(5)H(7)N(2))(4)[Co(C(3)H(2)O(4))(2)(H(2)O)(2)](PF(6))(2) (3) [C(5)H(7)N(2) = protonated 2-aminopyridine, C(3)H(4)O(4) = malonic acid, NO(3)(-) = nitrate, ClO(4)(-) = perchlorate, PF(6)(-) = hexafluorophosphate], have been synthesized from purely aqueous media, and their crystal structures have been determined by single crystal X-ray diffraction. A thorough analysis of Hirshfeld surfaces and fingerprint plots facilitates a comparison of intermolecular interactions in 1-3, which are crucial in building supramolecular architectures. When these complexes are structurally compared with their previously reported analogous Ni(II) or Mg(II) compounds, a very interesting feature regarding the role of counteranions has emerged. This phenomenon can be best described as anion-induced formation of extended supramolecular networks of the type lone pair-π/π-π/π-anion-π/π-lone pair and lone pair-π/π-π/π-anion involving various weak forces like lone pair-π, π-π, and anion-π interactions. The strength of these π contacts has been estimated using DFT calculations (M06/6-31+G*), and the formation energy of the supramolecular networks has been also evaluated. The influence of the anion (NO(3)(-), ClO(4)(-), and PF(6)(-)) on the total interaction energy of the assembly is also studied.

  10. Facile synthesis of 1-alkoxy-1H-benzo- and 7-azabenzotriazoles from peptide coupling agents, mechanistic studies, and synthetic applications

    PubMed Central

    Singh, Manish K; Kumar, Mukesh; Chamala, Raghu Ram; Yedulla, Vijayender R; Wagner, Domenick; Leung, Evan; Yang, Lijia; Matin, Asha; Ahmad, Sadia

    2014-01-01

    Summary (1H-Benzo[d][1,2,3]triazol-1-yloxy)tris(dimethylamino)phosphonium hexafluorophosphate (BOP), 1H-benzo[d][1,2,3]triazol-1-yl 4-methylbenzenesulfonate (Bt-OTs), and 3H-[1,2,3]triazolo[4,5-b]pyridine-3-yl 4-methylbenzenesulfonate (At-OTs) are classically utilized in peptide synthesis for amide-bond formation. However, a previously undescribed reaction of these compounds with alcohols in the presence of a base, leads to 1-alkoxy-1H-benzo- (Bt-OR) and 7-azabenzotriazoles (At-OR). Although BOP undergoes reactions with alcohols to furnish 1-alkoxy-1H-benzotriazoles, Bt-OTs proved to be superior. Both, primary and secondary alcohols undergo reaction under generally mild reaction conditions. Correspondingly, 1-alkoxy-1H-7-azabenzotriazoles were synthesized from At-OTs. Mechanistically, there are three pathways by which these peptide-coupling agents can react with alcohols. From 31P{1H}, [18O]-labeling, and other chemical experiments, phosphonium and tosylate derivatives of alcohols seem to be intermediates. These then react with BtO− and AtO− produced in situ. In order to demonstrate broader utility, this novel reaction has been used to prepare a series of acyclic nucleoside-like compounds. Because BtO− is a nucleofuge, several Bt-OCH2Ar substrates have been evaluated in nucleophilic substitution reactions. Finally, the possible formation of Pd π–allyl complexes by departure of BtO− has been queried. Thus, alpha-allylation of three cyclic ketones was evaluated with 1-(cinnamyloxy)-1H-benzo[d][1,2,3]triazole, via in situ formation of pyrrolidine enamines and Pd catalysis. PMID:25246951

  11. Metal-organic framework supported ionic liquid membranes for CO2 capture: anion effects.

    PubMed

    Gupta, Krishna M; Chen, Yifei; Hu, Zhongqiao; Jiang, Jianwen

    2012-04-28

    IRMOF-1 supported ionic liquid (IL) membranes are investigated for CO(2) capture by atomistic simulation. The ILs consist of identical cation 1-n-butyl-3-methylimidazolium [BMIM](+), but four different anions, namely hexafluorophosphate [PF(6)](-), tetrafluoroborate [BF(4)](-), bis(trifluoromethylsulfonyl)imide [Tf(2)N](-), and thiocyanate [SCN](-). As compared with the cation, the anion has a stronger interaction with IRMOF-1 and a more ordered structure in IRMOF-1. The small anions [PF(6)](-), [BF(4)](-), and [SCN](-) prefer to locate near to the metal-cluster, particularly the quasi-spherical [PF(6)](-) and [BF(4)](-). In contrast, the bulky and chain-like [BMIM](+) and [Tf(2)N](-) reside near the phenyl ring. Among the four anions, [Tf(2)N](-) has the weakest interaction with IRMOF-1 and thus the strongest interaction with [BMIM](+). With increasing the weight ratio of IL to IRMOF-1 (W(IL/IRMOF-1)), the selectivity of CO(2)/N(2) at infinite dilution is enhanced. At a given W(IL/IRMOF-1), the selectivity increases as [Tf(2)N](-) < [PF(6)](-) < [BF(4)](-) < [SCN](-). This hierarchy is predicted by the COSMO-RS method, and largely follows the order of binding energy between CO(2) and anion estimated by ab initio calculation. In the [BMIM][SCN]/IRMOF-1 membrane with W(IL/IRMOF-1) = 1, [SCN](-) is identified to be the most favorable site for CO(2) adsorption. [BMIM][SCN]/IRMOF-1 outperforms polymer membranes and polymer-supported ILs in CO(2) permeability, and its performance surpasses Robeson's upper bound. This simulation study reveals that the anion has strong effects on the microscopic properties of ILs and suggests that MOF-supported ILs are potentially intriguing for CO(2) capture.

  12. Modeling viscosity and conductivity of lithium salts in γ-butyrolactone

    NASA Astrophysics Data System (ADS)

    Chagnes, A.; Carré, B.; Willmann, P.; Lemordant, D.

    Viscosity and conductivity properties of Li-salts (lithium tetrafluoroborate (LiBF 4), lithium hexafluorophosphate (LiPF 6), lithium hexafluoroarsenate (LiAsF 6), lithium bis-(trifluoromethylsulfone)-imide (LiTFSI)) dissolved in γ-butyrolactone (BL) have been investigated. The B- and D-coefficients of the Jones-Dole (JD) equation for the relative viscosity of concentrated electrolyte solutions (concentration: C=0.1-1.5 M): ηr=1+ AC1/2+ BC+ DC2, have been determined as a function of the temperature. The B-coefficient is linked to the hydrodynamic volume of the solute and remains constant within the temperature range investigated (25-55 °C). The D-coefficient, which originates mainly from long-range coulombic ion-ion interactions, is a reciprocal function of the temperature. The variations of the molar conductivity ( Λ) with C follow the cube root law Λ= Λ0'- S' C1/3 issued from quasi-lattice theory of electrolyte solutions. From the Walden product W= Λη which does not vary with C and the JD equation, the bell shape of the conductivity-concentration relationship is explained and it is shown that the concentration in salt at the maximum of conductivity is linked to the D-coefficient. Raman spectroscopy has been used as an additional tool to investigate ion pairing in BL. Ions pairs have been evidenced for LiClO 4 solutions in BL but not for LiPF 6. As little variations occur for the ions pairs dissociation coefficient when the salt concentration is increased, the cube root law remains valid, at least in the concentration range investigated.

  13. A new dispersive liquid-liquid microextraction using ionic liquid based microemulsion coupled with cloud point extraction for determination of copper in serum and water samples.

    PubMed

    Arain, Salma Aslam; Kazi, Tasneem Gul; Afridi, Hassan Imran; Arain, Mariam Shahzadi; Panhwar, Abdul Haleem; Khan, Naeemullah; Baig, Jameel Ahmed; Shah, Faheem

    2016-04-01

    A simple and rapid dispersive liquid-liquid microextraction procedure based on ionic liquid assisted microemulsion (IL-µE-DLLME) combined with cloud point extraction has been developed for preconcentration copper (Cu(2+)) in drinking water and serum samples of adolescent female hepatitits C (HCV) patients. In this method a ternary system was developed to form microemulsion (µE) by phase inversion method (PIM), using ionic liquid, 1-butyl-3-methylimidazolium hexafluorophosphate ([C4mim][PF6]) and nonionic surfactant, TX-100 (as a stabilizer in aqueous media). The Ionic liquid microemulsion (IL-µE) was evaluated through visual assessment, optical light microscope and spectrophotometrically. The Cu(2+) in real water and aqueous acid digested serum samples were complexed with 8-hydroxyquinoline (oxine) and extracted into IL-µE medium. The phase separation of stable IL-µE was carried out by the micellar cloud point extraction approach. The influence of of different parameters such as pH, oxine concentration, centrifugation time and rate were investigated. At optimized experimental conditions, the limit of detection and enhancement factor were found to be 0.132 µg/L and 70 respectively, with relative standard deviation <5%. In order to validate the developed method, certified reference materials (SLRS-4 Riverine water) and human serum (Sero-M10181) were analyzed. The resulting data indicated a non-significant difference in obtained and certified values of Cu(2+). The developed procedure was successfully applied for the preconcentration and determination of trace levels of Cu(2+) in environmental and biological samples.

  14. Microemulsions of water in supercritical carbon dioxide : an in-situ NMR investigation of micelle formation and structure.

    SciTech Connect

    Fremgen, D. E.; Smotkin, E. S.; Gerald, R. E.; Klingler, R. J.; Rathke, J. W.; Chemical Engineering; IIT

    2001-04-01

    High-pressure NMR spectroscopy was used for the first time to investigate microemulsions of water in supercritical carbon dioxide. The emulsions were formed using a family of anionic perfluoropolyether ammonium carboxylate surfactants. This system holds promise as a reaction medium for conducting homogeneous catalytic reactions within the aqueous micellular cores while, at the same time, exploiting the facile mass transfer properties of the supercritical fluid. Ammonium hexafluorophosphate was used as a water-soluble ionic guest to investigate micelle formation and structure. Under micelle-forming conditions, the PF{sub 6}{sup -} guest, surfactant, and water were uniformly dispersed throughout the CO{sub 2} phase, as demonstrated by in situ NMR imaging. In addition, the micelles were observed to form even in the absence of mechanical stirring. This spontaneous formation of micelles demonstrates that the NMR spectral properties were obtained under conditions that result in the production of thermodynamically stable microemulsions. The nuclear overhauser effect (NOE) was used to probe the micellular structure through dipole-dipole interactions between the PF{sub 6}{sup -} anion and the fluorinated backbone of the surfactant. A strong negative homonuclear NoE was observed between the PF{sub 6}{sup -} guest and the fluorine moiety that is located directly adjacent to the surfactant's carboxylate head group. This highly specific negative NOE indicates an ordered arrangement, where the PF{sub 6}{sup -} anion and carboxylate ion are located in close proximity to one another. This close association of two negatively charged ionic groups in an aqueous environment is unusual and suggests that the PF{sub 6}{sup -} guest is concentrated within the electric double layer that forms at the micellular interface.

  15. The Importance of Ion Size and Electrode Curvature on Electrical Double Layers in Ionic Liquids

    SciTech Connect

    Feng, Guang; Qiao, Rui; Huang, Jingsong; Dai, Sheng; Sumpter, Bobby G; Meunier, Vincent

    2010-01-01

    Room-temperature ionic liquids (ILs) are an emerging class of electrolytes for supercapacitors. We investigate the effects of ion size and electrode curvature on the electrical double layers (EDLs) in two ILs 1-butyl-3-methylimidazolium chloride [BMIM][Cl] and 1-butyl-3-methylimidazolium hexafluorophosphate [BMIM][PF(6)], using a combination of molecular dynamics (MD) and quantum density functional theory (DFT) simulations. The sizes of the counter-ion and co-ion affect the ion distribution and orientational structure of EDLs. The EDL capacitances near both planar and cylindrical electrodes were found to follow the order: [BMIM][Cl] (near the positive electrode) > [BMIM][PF(6)] (near the positive electrode) {approx} [BMIM][Cl] (near the negative electrode) {approx} [BMIM][PF(6)] (near the negative electrode). The EDL capacitance was also found to increase as the electrode curvature increases. These capacitance data can be fit to the Helmholtz model and the recently proposed exohedral electrical double-cylinder capacitor (xEDCC) model when the EDL thickness is properly parameterized, even though key features of the EDLs in ILs are not accounted for in these models. To remedy the shortcomings of existing models, we propose a 'Multiple Ion Layers with Overscreening' (MILO) model for the EDLs in ILs that takes into account two critical features of such EDLs, i.e., alternating layering of counter-ions and co-ions and charge overscreening. The capacitance computed from the MILO model agrees well with the MD prediction. Although some input parameters of the MILO model must be obtained from MD simulations, the MILO model may provide a new framework for understanding many important aspects of EDLs in ILs (e.g., the variation of EDL capacitance with the electrode potential) that are difficult to interpret using classical EDL models and experiments.

  16. The importance of ion size and electrode curvature on electrical double layers in ionic liquids

    SciTech Connect

    Feng, G.; Qiao, R.; Huang, J; Dai, S.; Sumpter, B. G.; Meunier, V.

    2011-01-01

    Room-temperature ionic liquids (ILs) are an emerging class of electrolytes for supercapacitors. We investigate the effects of ion size and electrode curvature on the electrical double layers (EDLs) in two ILs 1-butyl-3-methylimidazolium chloride [BMIM][Cl] and 1-butyl-3-methylimidazolium hexafluorophosphate [BMIM][PF{sub 6}], using a combination of molecular dynamics (MD) and quantum density functional theory (DFT) simulations. The sizes of the counter-ion and co-ion affect the ion distribution and orientational structure of EDLs. The EDL capacitances near both planar and cylindrical electrodes were found to follow the order: [BMIM][Cl] (near the positive electrode) > [BMIM][PF{sub 6}] (near the positive electrode) ≈ [BMIM][Cl] (near the negative electrode) ≈ [BMIM][PF{sub 6}] (near the negative electrode). The EDL capacitance was also found to increase as the electrode curvature increases. These capacitance data can be fit to the Helmholtz model and the recently proposed exohedral electrical double-cylinder capacitor (xEDCC) model when the EDL thickness is properly parameterized, even though key features of the EDLs in ILs are not accounted for in these models. To remedy the shortcomings of existing models, we propose a “Multiple Ion Layers with Overscreening” (MILO) model for the EDLs in ILs that takes into account two critical features of such EDLs, i.e., alternating layering of counter-ions and co-ions and charge overscreening. The capacitance computed from the MILO model agrees well with the MD prediction. Although some input parameters of the MILO model must be obtained from MD simulations, the MILO model may provide a new framework for understanding many important aspects of EDLs in ILs (e.g., the variation of EDL capacitance with the electrode potential) that are difficult to interpret using classical EDL models and experiments.

  17. Optimized syntheses of Fmoc azido amino acids for the preparation of azidopeptides

    PubMed Central

    Pícha, Jan; Buděšínský, Miloš; Macháčková, Kateřina; Collinsová, Michaela

    2017-01-01

    The rise of CuI‐catalyzed click chemistry has initiated an increased demand for azido and alkyne derivatives of amino acid as precursors for the synthesis of clicked peptides. However, the use of azido and alkyne amino acids in peptide chemistry is complicated by their high cost. For this reason, we investigated the possibility of the in‐house preparation of a set of five Fmoc azido amino acids: β‐azido l‐alanine and d‐alanine, γ‐azido l‐homoalanine, δ‐azido l‐ornithine and ω‐azido l‐lysine. We investigated several reaction pathways described in the literature, suggested several improvements and proposed several alternative routes for the synthesis of these compounds in high purity. Here, we demonstrate that multigram quantities of these Fmoc azido amino acids can be prepared within a week or two and at user‐friendly costs. We also incorporated these azido amino acids into several model tripeptides, and we observed the formation of a new elimination product of the azido moiety upon conditions of prolonged couplings with 2‐(1H‐benzotriazol‐1‐yl)‐1,1,3,3‐tetramethyluronium hexafluorophosphate/DIPEA. We hope that our detailed synthetic protocols will inspire some peptide chemists to prepare these Fmoc azido acids in their laboratories and will assist them in avoiding the too extensive costs of azidopeptide syntheses. Experimental procedures and/or analytical data for compounds 3–5, 20, 25, 26, 30 and 43–47 are provided in the supporting information. © 2017 The Authors Journal of Peptide Science published by European Peptide Society and John Wiley & Sons Ltd. PMID:28120383

  18. Comparison of two ionic liquid dispersive liquid-liquid microextraction approaches for the determination of benzoylurea insecticides in wastewater using liquid chromatography-quadrupole-linear ion trap-mass spectrometry: evaluation of green parameters.

    PubMed

    Vázquez, M M Parrilla; Vázquez, P Parrilla; Galera, M Martínez; Moreno, A Uclés

    2014-08-22

    Two dispersive liquid-liquid microextraction (DLLME) approaches including temperature-controlled ionic liquid dispersive liquid-liquid microextraction (TCIL-DLLME) and ultrasound-assisted ionic liquid dispersive liquid-liquid microextraction (US-IL-DLLME) were compared for the extraction of six benzoylurea insecticides (diflubenzuron, triflumuron, hexaflumuron, teflubenzuron, lufenuron and flufenoxuron) from wastewater samples prior to their determination by high-performance liquid chromatography with a hybrid triple quadrupole-linear ion trap-mass spectrometer (LC-QqLIT-MS/MS). Influential parameters affecting extraction efficiency were systematically studied and optimized and the most significant green parameters were quantified and compared. The best results were obtained using the US-IL-DLLME procedure, which employed the IL 1-octyl-3-methylimidazolium hexafluorophosphate ([C8MIM][PF6]) and methanol (MeOH) as extraction and disperser solvent, respectively. US-IL-DLLME procedure was fast, easy, low environmental toxicity and, it was also able to successfully extract all selected benzoylureas. This method was extensively validated with satisfactory results: limits of detection and quantification were in the range 0.5-1.0 ng L(-1) and 1.5-3.5 ng L(-1), respectively, whereas recovery rates ranged from 89 to 103% and the relative standard deviations were lower than 13.4%. The applicability of the method was assessed with the analysis of effluent wastewater samples from a wastewater treatment plant located in an agricultural zone of Almería (Spain) and the results indicated the presence of teflubenzuron at mean concentration levels of 11.3 ng L(-1). US-IL-DLLME sample treatment in combination with LC-QqLIT-MS/MS has demonstrated to be a sensitive, selective and efficient method to determine benzoylurea insecticides in wastewaters at ultra-trace levels.

  19. Rapid determination of phthalate esters in alcoholic beverages by conventional ionic liquid dispersive liquid-liquid microextraction coupled with high performance liquid chromatography.

    PubMed

    Fan, Yingying; Liu, Shuhui; Xie, Qilong

    2014-02-01

    A very simple, fast and environmentally friendly sample extraction method was proposed for the analysis of phthalate esters (PAEs, di-isobutyl phthalate (DIBP), dibutylphthalate (DBP), butylbenzylphthalate (BBP) and bis(2-ethylhexyl)phthalate (DEHP)) in alcoholic beverages by using conventional ionic liquid dispersive liquid-liquid microextraction. The samples were extracted by 160 μL 1-octyl-3-methylimidazolium hexafluorophosphate in the presence of appropriate amount of ethanol and 10% (w/v) sodium chloride solution; the enriched analytes in sedimented phases were analyzed by high performance liquid chromatography-diode array detector (HPLC-DAD). Under the optimum conditions, a satisfactory linearity (in the range of 0.02-1 μg mL(-1) for white spirits and 0.01-0.5 μg mL(-1) for red wines with the correlation coefficients (r) varying from 0.9983 to 1), acceptable recovery rates (88.5-103.5% for white spirits and 91.6-104.6% for red wines), good repeatability (RSD ≤ 8.0%) and low detection limits (3.1-4.2 ng mL(-1) for white spirits and 1.5-2.2 ng mL(-1) for red wines) were obtained. The developed method was successfully applied for the determination of the four PAEs in 30 white spirits and 11 red wines collected locally, and the DBP content in 63% (19:30) white spirits exceeded the specific migration limit of 0.3 mg kg(-1) established by international regulation.

  20. Polymeric ionic liquid modified graphene oxide-grafted silica for solid-phase extraction to analyze the excretion-dynamics of flavonoids in urine by Box-Behnken statistical design.

    PubMed

    Hou, Xiudan; Liu, Shujuan; Zhou, Panpan; Li, Jin; Liu, Xia; Wang, Licheng; Guo, Yong

    2016-07-22

    A solid-phase extraction method for the efficient analysis of the excretion-dynamics of flavonoids in urine was established and described. In this work, in situ surface radical chain-transfer polymerization and in situ anion exchange were utilized to tune the extraction performance of poly(1-vinyl-3-hexylimidazolium bromide)-graphene oxide-grafted silica (poly(VHIm(+)Br(-))@GO@Sil). Graphene oxide (GO) was first coated onto the silica using a layer-by-layer fabrication method, and then the anion of poly(VHIm(+)Br(-))@GO@Sil was changed into hexafluorophosphate (PF6(-)) by in situ anion exchange. The interaction energies between two PILs and four flavonoids were calculated with the Gaussian09 suite of programs. A Box-Behnken design was used for the optimization of four greatly influential parameters after single-factor experiments to obtain more accurate and precise results. Coupled to high performance liquid chromatography, the poly(VHIm(+)PF6(-))@GO@Sil method showed acceptable extraction recoveries for the four flavonoids, with limits of detection in the range of 0.1-0.5μgL(-1), and wide linear ranges with correlation coefficients (R) ranging from 0.9935 to 0.9987. Under the optimum conditions, the proposed method was applied to analyze the urines collected from a healthy volunteer. The excretion amount-time profiles revealed that 4-15h was the main excretion time for the detected flavonoids. The results indicated that the newly developed method offered the advantages of being feasible, green and cost-effective, and could be successfully applied to the extraction and enrichment of flavonoids in human body systems allowing the study of the metabolic kinetics.

  1. Synthesis and redox activity of "clicked" triazolylbiferrocenyl polymers, network encapsulation of gold and silver nanoparticles and anion sensing.

    PubMed

    Rapakousiou, Amalia; Deraedt, Christophe; Irigoyen, Joseba; Wang, Yanlan; Pinaud, Noël; Salmon, Lionel; Ruiz, Jaime; Moya, Sergio; Astruc, Didier

    2015-03-02

    The design of redox-robust polymers is called for in view of interactions with nanoparticles and surfaces toward applications in nanonetwork design, sensing, and catalysis. Redox-robust triazolylbiferrocenyl (trzBiFc) polymers have been synthesized with the organometallic group in the side chain by ring-opening metathesis polymerization using Grubbs-III catalyst or radical polymerization and with the organometallic group in the main chain by Cu(I) azide alkyne cycloaddition (CuAAC) catalyzed by [Cu(I)(hexabenzyltren)]Br. Oxidation of the trzBiFc polymers with ferricenium hexafluorophosphate yields the stable 35-electron class-II mixed-valent biferrocenium polymer. Oxidation of these polymers with Au(III) or Ag(I) gives nanosnake-shaped networks (observed by transmission electron microscopy and atomic force microscopy) of this mixed-valent Fe(II)Fe(III) polymer with encapsulated metal nanoparticles (NPs) when the organoiron group is located on the side chain. The factors that are suggested to be synergistically responsible for the NP stabilization and network formation are the polymer bulk, the trz coordination, the nearby cationic charge of trzBiFc, and the inter-BiFc distance. For instance, reduction of such an oxidized trzBiFc-AuNP polymer to the neutral trzBiFc-AuNP polymer with NaBH4 destroys the network, and the product flocculates. The polymers easily provide modified electrodes that sense, via the oxidized Fe(II)Fe(III) and Fe(III)Fe(III) polymer states, respectively, ATP(2-) via the outer ferrocenyl units of the polymer and Pd(II) via the inner Fc units; this recognition works well in dichloromethane, but also to a lesser extent in water with NaCl as the electrolyte.

  2. Properties of an ionic liquid-tolerant Bacillus amyloliquefaciens CMW1 and its extracellular protease.

    PubMed

    Kurata, Atsushi; Senoo, Humiya; Ikeda, Yasuyuki; Kaida, Hideaki; Matsuhara, Chiaki; Kishimoto, Noriaki

    2016-07-01

    An ionic liquid-tolerant bacterium, Bacillus amyloliquefaciens CMW1, was isolated from a Japanese fermented soybean paste. Strain CMW1 grew in the presence of 10 % (v/v) 1-butyl-3-methylimidazolium chloride ([BMIM]Cl), a commonly used ionic liquid. Additionally, strain CMW1 grew adequately in the presence of the hydrophilic ionic liquids 10 % (v/v) 1-ethyl-3-methylimidazolium trifluoromethanesulfonate ([EMIM]CF3SO3) or 2.5 % (v/v) 1-butyl-3-methylimidazolium trifluoromethanesulfonate ([BMIM]CF3SO3). Strain CMW1 produced an extracellular protease (BapIL) in the culture medium. BapIL was stable in the presence of 80 % (v/v) ionic liquids, [EMIM]CF3SO3, [BMIM]Cl, [BMIM]CF3SO3, 1-butyl-3-methylimidazolium tetrafluoroborate, 1-butyl-3-methylimidazolium hexafluorophosphate, and 1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide, and functioned in 10 % (v/v) these ionic liquids. BapIL was stable at pH 4.0-12.6 or in 4004 mM NaCl solution, and exhibited activity in the presence of 50 % (v/v) hydrophilic or hydrophobic organic solvents. BapIL was completely inhibited by 1 mM PMSF and partially by 5 mM EDTA. BapIL belongs to the true subtilisins according to analysis of the deduced amino acid sequence. We showed that BapIL from the ionic liquid-tolerant B. amyloliquefaciens CMW1 exhibited tolerance to ionic liquid and halo, alkaline, and organic solvents.

  3. Ultrafast vibrational spectroscopy (2D-IR) of CO{sub 2} in ionic liquids: Carbon capture from carbon dioxide’s point of view

    SciTech Connect

    Brinzer, Thomas; Berquist, Eric J.; Ren, Zhe; Dutta, Samrat; Johnson, Clinton A.; Krisher, Cullen S.; Lambrecht, Daniel S.; Garrett-Roe, Sean

    2015-06-07

    The CO{sub 2}ν{sub 3} asymmetric stretching mode is established as a vibrational chromophore for ultrafast two-dimensional infrared (2D-IR) spectroscopic studies of local structure and dynamics in ionic liquids, which are of interest for carbon capture applications. CO{sub 2} is dissolved in a series of 1-butyl-3-methylimidazolium-based ionic liquids ([C{sub 4}C{sub 1}im][X], where [X]{sup −} is the anion from the series hexafluorophosphate (PF{sub 6}{sup −}), tetrafluoroborate (BF{sub 4}{sup −}), bis-(trifluoromethyl)sulfonylimide (Tf{sub 2}N{sup −}), triflate (TfO{sup −}), trifluoroacetate (TFA{sup −}), dicyanamide (DCA{sup −}), and thiocyanate (SCN{sup −})). In the ionic liquids studied, the ν{sub 3} center frequency is sensitive to the local solvation environment and reports on the timescales for local structural relaxation. Density functional theory calculations predict charge transfer from the anion to the CO{sub 2} and from CO{sub 2} to the cation. The charge transfer drives geometrical distortion of CO{sub 2}, which in turn changes the ν{sub 3} frequency. The observed structural relaxation timescales vary by up to an order of magnitude between ionic liquids. Shoulders in the 2D-IR spectra arise from anharmonic coupling of the ν{sub 2} and ν{sub 3} normal modes of CO{sub 2}. Thermal fluctuations in the ν{sub 2} population stochastically modulate the ν{sub 3} frequency and generate dynamic cross-peaks. These timescales are attributed to the breakup of ion cages that create a well-defined local environment for CO{sub 2}. The results suggest that the picosecond dynamics of CO{sub 2} are gated by local diffusion of anions and cations.

  4. Combination of ionic liquid-based dispersive liquid-liquid micro-extraction with stopped-flow spectrofluorometry for the pre-concentration and determination of aluminum in natural waters, fruit juice and food samples.

    PubMed

    Abdolmohammad-Zadeh, H; Sadeghi, G H

    2010-05-15

    In this research, we combined ionic liquid-based dispersive liquid-liquid micro-extraction (IL-based DLLME) with stopped-flow spectrofluorometry (SFS) to evaluate the concentration of aluminum in different real samples at trace level. 1-Hexylpyridinium hexafluorophosphate [Hpy][PF(6)] ionic liquid and 8-hydroxyquinoline (oxine), which forms a highly fluorescent complex with Al(3+), were chosen as the extraction solvent and chelating agent, respectively. The hydrophobic Al-oxine complex was extracted into the [Hpy][PF(6)] and separated from the aqueous phase. Then, the concentration of the enriched aluminum in the sediment phase was determined by SFS. Some effective parameters that influence the SFS signals and the micro-extraction efficiency, such as the suction and sending time, the concentration of the chelating agent, pH, the amount of the ionic liquid, the type of disperser solvent and diluting agent, ionic strength, extraction time, equilibration temperature and centrifugation time were investigated and optimized. In the optimum experimental conditions, the limit of detection (3s) and enrichment factor were 0.05microgL(-1) and 100, respectively. The relative standard deviation (RSD) for six replicate determinations of 6microgL(-1) Al was 1.7%. The calibration graph using the pre-concentration system was linear in the range of 0.06-15microgL(-1) with a correlation coefficient of 0.9989. The developed method was validated by the analysis of certified reference materials and applied successfully to the determination of aluminum in several water, fruit juice and food samples.

  5. Temperature controlled ionic liquid-based dispersive micro-extraction using two ligands, for determination of aluminium in scalp hair samples of Alzheimer's patients: a multivariate study.

    PubMed

    Arain, Mariam S; Arain, Salma A; Kazi, Tasneem G; Afridi, Hassan I; Ali, Jamshaid; Naeemulllah; Arain, Sadaf S; Brahman, Kapil Dev; Mughal, Moina Akhtar

    2015-02-25

    A green and sensitive temperature controlled dispersive liquid-liquid microextraction (TIL-DLLME) methodology based on the application of ionic liquid 1-butyl-3-methylimidazolium hexafluorophosphate, [C4mim][PF6], as an extractant solvent was proposed for the preconcentration of trace levels of aluminium (Al(3+)) in scalp hair samples of Alzheimer's (AD) patients, prior to analyzing by flame atomic absorption spectrometry (FAAS). The Al(3+) was complexed with 8-hydrooxyquinoline (oxine) (L1) and 3,5,7,2'-4' pentahydroxy flavone (morin) (L2) separately and then extracted by IL at temperature (50±2.0°C). Some effective factors that influence the TIL-DLLME efficiency such as pH, ligands concentrations, volume of IL, ionic strength, and incubation time were investigated and optimized by multivariate analysis. In the optimum experimental conditions, the limit of detection (3s) and enhancement factor were 0.56 μg L(-1), 0.64 μg L(-1) and 85, 73 for both ligands, respectively. The relative standard deviation (RSD) for six replicate determinations of 100 μg L(-1) Al(3+) complexed with oxine and morin were found to be 3.88% and 4.74%, respectively. The developed method was validated by the analysis of certified reference material of human hair (NCSZC81002).and applied satisfactorily to the determination of Al(3+) in acid digested scalp hair samples of AD patients and healthy controls. The resulted data shows significant higher level in scalp hair samples of AD male patients with related to referents of same age and socioeconomic status.

  6. Ionic liquid-based dispersive liquid-liquid microextraction followed high-performance liquid chromatography for the determination of organophosphorus pesticides in water sample.

    PubMed

    He, Lijun; Luo, Xianli; Xie, Hongxue; Wang, Chunjian; Jiang, Xiuming; Lu, Kui

    2009-11-23

    Using 1-octyl-3-methylimidazolium hexafluorophosphate ([C(8)MIM][PF(6)]) ionic liquid as extraction solvent, organophosphorus pesticides (OPPs) (parathion, phoxim, phorate and chlorpyifos) in water were determined by dispersive liquid-liquid microextraction (DLLME) combined with high-performance liquid chromatography (HPLC). The extraction procedure was induced by the formation of cloudy solution, which was composed of fine drops of [C(8)MIM][PF(6)] dispersed entirely into sample solution with the help of disperser solvent (methanol). Parameters including extraction solvent and its volume, disperser solvent and its volume, extraction time, centrifugal time, salt addition, extraction temperature and sample pH were investigated and optimized. Under the optimized conditions, up to 200-fold enrichment factor of analytes and acceptable extraction recovery (>70%) were obtained. The calibration curves were linear in the concentration range of 10.5-1045.0 microg L(-1) for parathion, 10.2-1020.0 microg L(-1) for phoxim, 54.5-1089.0 microg L(-1) for phorate and 27.2-1089.0 microg L(-1) for chlorpyifos, respectively. The limits of detection calculated at a signal-to-noise ratio of 3 were in the range of 0.1-5.0 microg L(-1). The relative standard deviations for seven replicate experiments at 200 microg L(-1) concentration level were less than 4.7%. The proposed method was applied to the analysis of four different sources water samples (tap, well, rain and Yellow River water) and the relative recoveries of spiked water samples are 99.9-115.4%, 101.8-113.7% and 87.3-117.6% at three different concentration levels of 75, 200 and 1000 microg L(-1), respectively.

  7. Light-reducible dissipative nanostructures formed at the solid-liquid interface.

    PubMed

    Soejima, Tetsuro; Amako, Yuta; Ito, Seishiro; Kimizuka, Nobuo

    2014-12-02

    Dissipative structures are macroscopic or even larger ordered structures that emerge under conditions far from thermodynamic equilibrium. In contrast, molecular self-assembly has been investigated near at the thermodynamic equilibrium, which provides basically smaller, nano-to-micron sized structures. In terms of the formation principles, there exists an essential gap between the dissipative structures and molecular self-assemblies. To fill this gap, molecular self-assembly of light-reducible organic-inorganic ion pairs was investigated under far-from-equilibrium conditions. When solid films of tetraalkylammonium hexafluorophosphate were immersed in aqueous Au(OH)4(-) and immediately photoirradiated, gold nanowires are formed at the solid-aqueous interface. On the other hand, such nanowires were not formed when the photoirradiation was conducted for the specimens after a prolonged immersion period of 60 min. These observations indicate spontaneous growth of dissipative nanofibrous self-assemblies consisting of light-reducible ion pairs [tetraalkylammonium ion][Au(OH)4(-)] at the interface and their photoreduction to give developed nanowires. These nanowires are not available by the photoreduction of Au(OH)4(-) ions under conditions near at the thermodynamic equilibrium. A picture for the dissipative nanostructures is obtained: the formation of amphiphilic light-reducible nanowire structures is based on the static self-assembly near at the thermodynamic equilibrium, whereas their spontaneous, anisotropic growth from the interface to the aqueous phase is directed by dynamic, dissipative self-assembly phenomena under the far-from-equilibrium conditions. Thus, the both elements of dissipative self-assembly (dynamic) and static molecular self-assembly fuse together at the nanoscale, which is an essential feature of the dissipative nanostructures.

  8. Effects of electrolyte salts on the performance of Li-O2 batteries

    SciTech Connect

    Nasybulin, Eduard N.; Xu, Wu; Engelhard, Mark H.; Nie, Zimin; Burton, Sarah D.; Cosimbescu, Lelia; Gross, Mark E.; Zhang, Jiguang

    2013-02-05

    It is well known that the stability of nonaqueous electrolyte is critical for the rechargeable Li-O2 batteries. Although stability of many solvents used in the electrolytes has been investigated, considerably less attention has been paid to the stability of electrolyte salt which is the second major component. Herein, we report the systematic investigation of the stability of seven common lithium salts in tetraglyme used as electrolytes for Li-O2 batteries. The discharge products of Li-O2 reaction were analyzed by X-ray diffraction, X-ray photoelectron spectroscopy and nuclear magnetic resonance spectroscopy. The performance of Li-O2 batteries was strongly affected by the salt used in the electrolyte. Lithium tetrafluoroborate (LiBF4) and lithium bis(oxalato)borate (LiBOB) decompose and form LiF and lithium borates, respectively during the discharge of Li-O2 batteries. Several other salts, including lithium bis(trifluoromethane)sulfonamide (LiTFSI), lithium trifluoromethanesulfonate (LiTf), lithium hexafluorophosphate (LiPF6), lithium perchlorate (LiClO4) , and lithium bromide (LiBr) led to the discharge products which mainly consisted of Li2O2 and only minor signs of decomposition of LiTFSI, LiTf, LPF6 and LiClO4 were detected. LiBr showed the best stability during the discharge process. As for the cycling performance, LiTf and LiTFSI were the best among the studied salts. In addition to the instability of lithium salts, decomposition of tetraglyme solvent was a more significant factor contributing to the limited cycling stability. Thus a more stable nonaqueous electrolyte including organic solvent and lithium salt still need to be further developed to reach a fully reversible Li-O2 battery.

  9. Deep eutectic solvents based on N-methylacetamide and a lithium salt as suitable electrolytes for lithium-ion batteries.

    PubMed

    Boisset, Aurélien; Menne, Sebastian; Jacquemin, Johan; Balducci, Andrea; Anouti, Mérièm

    2013-12-14

    In this work, we present a study on the physical and electrochemical properties of three new Deep Eutectic Solvents (DESs) based on N-methylacetamide (MAc) and a lithium salt (LiX, with X = bis[(trifluoromethyl)sulfonyl]imide, TFSI; hexafluorophosphate, PF6; or nitrate, NO3). Based on DSC measurements, it appears that these systems are liquid at room temperature for a lithium salt mole fraction ranging from 0.10 to 0.35. The temperature dependences of the ionic conductivity and the viscosity of these DESs are correctly described by using the Vogel-Tammann-Fulcher (VTF) type fitting equation, due to the strong interactions between Li(+), X(-) and MAc in solution. Furthermore, these electrolytes possess quite large electrochemical stability windows up to 4.7-5 V on Pt, and demonstrate also a passivating behavior toward the aluminum collector at room temperature. Based on these interesting electrochemical properties, these selected DESs can be classified as potential and promising electrolytes for lithium-ion batteries (LIBs). For this purpose, a test cell was then constructed and tested at 25 °C, 60 °C and 80 °C by using each selected DES as an electrolyte and LiFePO4 (LFP) material as a cathode. The results show a good compatibility between each DES and LFP electrode material. A capacity of up to 160 mA h g(-1) with a good efficiency (99%) is observed in the DES based on the LiNO3 salt at 60 °C despite the presence of residual water in the electrolyte. Finally preliminary tests using a LFP/DES/LTO (lithium titanate) full cell at room temperature clearly show that LiTFSI-based DES can be successfully introduced into LIBs. Considering the beneficial properties, especially, the cost of these electrolytes, such introduction could represent an important contribution for the realization of safer and environmentally friendly LIBs.

  10. Investigations of oxygen reduction reactions in non-aqueous electrolytes and the lithium-air battery

    NASA Astrophysics Data System (ADS)

    O'Laoire, Cormac Micheal

    Unlocking the true energy capabilities of the lithium metal negative electrode in a lithium battery has until now been limited by the low capacity intercalation and conversion reactions at the positive electrodes. This is overcome by removing these electrodes and allowing lithium to react directly with oxygen in the atmosphere forming the Li-air battery. Chapter 2 discusses the intimate role of electrolyte, in particular the role of ion conducting salts on the mechanism and kinetics of oxygen reduction in non-aqueous electrolytes designed for such applications and in determining the reversibility of the electrode reactions. Such fundamental understanding of this high energy density battery is crucial to harnessing its full energy potential. The kinetics and mechanisms of O2 reduction in solutions of hexafluorophosphate salts of the general formula X+ PF6-, where, X = tetra butyl ammonium (TBA), K, Na and Li, in acetonitrile have been studied on glassy carbon electrodes using cyclic voltammetry (CV) and rotating disk electrode (RDE) techniques. Our results show that cation choice strongly influences the reduction mechanism of O2. Electrochemical data supports the view that alkali metal oxides formed via electrochemical and chemical reactions passivate the electrode surface inhibiting the kinetics and reversibility of the processes. The O2 reduction mechanisms in the presence of the different cations have been supplemented by kinetic parameters determined from detailed analyses of the CV and RDE data. The organic solvent present in the Li+-conducting electrolyte has a major role on the reversibility of each of the O2 reduction products as found from the work discussed in the next chapter. A fundamental study of the influence of solvents on the oxygen reduction reaction (ORR) in a variety of non-aqueous electrolytes was conducted in chapter 4. In this work special attention was paid to elucidate the mechanism of the oxygen electrode processes in the rechargeable Li

  11. Effect of electrolytes and temperature on dications and radical cations of carotenoids: Electrochemical, optical absorption, and high-performance liquid chromatography studies

    SciTech Connect

    He, Z.; Kispert, L.D.

    1999-11-25

    The effect of supporting electrolytes and temperature on the behavior of dications and radical cations of carotenoids is studied. Cyclic voltammograms (CVs) of canthaxanthin (I) at 23 and {minus}25 C show that Car{sup sm{underscore}bullet+} of I has similar stability during the time of the CV scan, when using tetrabutylammonium perchlorate (TBAPC), tetrabutylammonium tetrafluoroborate (TBATFB), or tetrabutylammonium hexafluorophosphate (TBAHFP) as supporting electrolyte. However, the stability of Car{sup 2+} decreases when using TBAPC or TBATFB; {beta}-carotene (II) shows similar behavior. The CV of I at {minus}25 C shows a strong cathodic wave (wave 6) near {minus}0.15 V (vs Ag) with an intensity about half that of the neutral oxidation wave when TBAPC or TBATFB is the supporting electrolyte. When TBAHFP is used, wave 6 (ca. {minus}0.05 V vs Ag) is ca. 8 times weaker than when TBAPC or TBATFB is used. This wave results from the reduction of a species that may be a decay product of Car{sup 2+} of I. Results show that these electrolytes commonly used in electrochemical studies may affect the studied systems to different extents. In simultaneous bulk electrolysis (BE) and optical absorption spectroscopic measurements, the absorption band of Car{sup 2+} of I in the presence of 0.1 M TBAHFP can be observed by lowering the BE temperature to {minus}20 C. In the presence of 0.1 M TBAPC or TBATFB, this band is not observed, even at {minus}50 C. Isomerization of neutral I (as shown by HPLC and its blue absorption band shift) is observed only when the Car{sup 2+} absorption band is absent during BE. This observation, along with an increase of the neutral absorption band after stopping BE, suggests that the equilibrium Car + Car{sup 2+} {r{underscore}equilibrium} 2Car{sup {sm{underscore}bullet}+} is shifted to the left because Car{sup 2+} decays more quickly than Car{sup {sm{underscore}bullet}+} in the presence of electrolyte and this is a major path for formation of cis

  12. Application of electrochemical methods in corrosion and battery research

    NASA Astrophysics Data System (ADS)

    Sun, Zhaoli

    Various electrochemical methods have been applied in the development of corrosion protection methods for ammonia/water absorption heat pumps and the evaluation of the stability of metallic materials in Li-ion battery electrolyte. Rare earth metal salts (REMSs) and organic inhibitors have been evaluated for corrosion protection of mild steel in the baseline solution of 5 wt% NH 3 + 0.2 wt% NaOH to replace the conventionally used toxic chromate salt inhibitors. Cerium nitrate provided at least comparable corrosion inhibition efficiency as dichromate in the baseline solution at 100°C. The cerium (IV) oxide formed on mild steel through the cerating process exhibited increasing corrosion protection for mild steel with prolonged exposure time in the hot baseline solution. The optimum cerating process was found to be first cerating in a solution of 2.3 g/L CeCl3 + 4.4 wt% H2O2 + appropriate additives for 20 minutes at pH 2.2 at room temperature with 30 minutes solution aging prior to use, then sealing in 10% sodium (meta) silicate or sodium molybdate at 50°C for 30 minutes. Yttrium salts provided less corrosion protection for mild steel in the baseline solution than cerium salts. Glycerophosphate was found to be a promising chromate-free organic inhibitor for mild steel; however, its thermostability in hot ammonia/water solutions has not been confirmed yet. The stability of six metallic materials used in Li-ion batteries has been evaluated in 1M lithium hexafluorophosphate (LiPF6) dissolved in a 1:1 volume mixture of ethylene carbonate and diethyl carbonate at 37°C in a dry-box. Aluminum is the most stable material, while Copper is active under anodic potentials and susceptible to localized corrosion and galvanic corrosion. The higher the concentration of the alloying elements Al and/or V in a titanium alloy, the higher was the stability of the titanium alloy in the battery electrolyte. 90Pt-10Ir can cause decomposition of the electrolyte resulting in a low stable

  13. LiGa(OTf)(sub 4) as an Electrolyte Salt for Li-Ion Cells

    NASA Technical Reports Server (NTRS)

    Reddy, V. Prakash; Prakash, G. K. Syria; Hu, Jinbo; Yan, Ping; Smart, Marshall; Bugga, ratnakumar; Chin, Keith; Surampudi, Subarao

    2008-01-01

    Lithium tetrakis(trifluoromethane sulfo - nato)gallate [abbreviated "LiGa(OTf)4" (wherein "OTf" signifies trifluoro - methanesulfonate)] has been found to be promising as an electrolyte salt for incorporation into both liquid and polymer electrolytes in both rechargeable and non-rechargeable lithium-ion electrochemical cells. This and other ingredients have been investigated in continuing research oriented toward im proving the performances of rechargeable lithium-ion electrochemical cells, especially at low temperatures. This research at earlier stages, and the underlying physical and chemical principles, were reported in numerous previous NASA Tech Briefs articles. As described in more detail in those articles, lithiumion cells most commonly contain nonaqueous electrolyte solutions consisting of lithium hexafluorophosphate (LiPF6) dissolved in mixtures of cyclic and linear alkyl carbonates, including ethylene carbonate (EC), propylene carbonate (PC), dimethyl carbonate (DMC), diethyl carbonate (DEC), and ethyl methyl carbonate (EMC). Although such LiPF6-based electrolyte solutions are generally highly ionically conductive and electrochemically stable, as needed for good cell performance, there is interest in identifying alternate lithium electrolyte salts that, relative to LiPF6, are more resilient at high temperature and are less expensive. Experiments have been performed on LiGa(OTf)4 as well as on several other candidate lithium salts in pursuit of this interest. As part of these experiments, LiGa(OTf)4 was synthesized by the reaction of Ga(OTf)3 with an equimolar portion of LiOTf in a solvent consisting of anhydrous acetonitrile. Evaporation of the solvent yielded LiGa(OTf)4 as a colorless crystalline solid. The LiGa(OTf)4 and the other salts were incorporated into solutions with PC and DMC. The resulting electrolyte solutions exhibited reasonably high ionic conductivities over a relatively wide temperature range down to 40 C (see figure). In cyclic

  14. Ionothermal synthesis of open-framework metal phosphates with a Kagomé lattice network exhibiting canted anti-ferromagnetism† †Electronic supplementary information (ESI) available: Cif files, atomic parameters, X-ray diffraction patterns, IR spectra, TG curves, and thermal ellipsoid plot and atomic label schemes of compound 1–4. See DOI: 10.1039/c4tc00290c Click here for additional data file.

    PubMed Central

    Wang, Guangmei; Valldor, Martin; Mallick, Bert

    2014-01-01

    Four open-framework transition-metal phosphates; (NH4)2Co3(HPO4)2F4 (1), (NH4)Co3(HPO4)2(H2PO4)F2 (2), KCo3(HPO4)2(H2PO4)F2 (3), and KFe3(HPO4)2(H2PO4)F2 (4); are prepared by ionothermal synthesis using pyridinium hexafluorophosphate as the ionic liquid. Single-crystal X-ray diffraction analyses reveal that the four compounds contain cobalt/iron–oxygen/fluoride layers with Kagomé topology composed of interlinked face-sharing MO3F3/MO4F2 octahedra. PO3OH pseudo-tetrahedral groups augment the [M3O6F4] (1)/[M3O8F2] layers on both sides to give M3(HPO4)2F4 (1) and M3(HPO4)2F2 (2–4) layers. These layers are stacked along the a axis in a sequence AA…, resulting in the formation of a layer structure for (NH4)2Co3(HPO4)2F4(1). In NH4Co3(HPO4)2(H2PO4)F2 and KM3(HPO4)2(H2PO4)F2, the M3(HPO4)2F2 layers are stacked along the a axis in a sequence AAi… and are connected by [PO3(OH)] tetrahedra, giving rise to a 3-D open framework structure with 10-ring channels along the [001] direction. The negative charges of the inorganic framework are balanced by K+/NH4 + ions located within the channels. The magnetic transition metal cations themselves form layers with stair-case Kagomé topology. Magnetic susceptibility and magnetization measurements reveal that all four compounds exhibit a canted anti-ferromagnetic ground state (T c = 10 or 13 K for Co and T c = 27 K for Fe) with different canting angles. The full orbital moment is observed for both Co2+ and Fe2+. PMID:25580250

  15. Etched Colloidal LiFePO4 Nanoplatelets toward High-Rate Capable Li-Ion Battery Electrodes

    PubMed Central

    2014-01-01

    LiFePO4 has been intensively investigated as a cathode material in Li-ion batteries, as it can in principle enable the development of high power electrodes. LiFePO4, on the other hand, is inherently “plagued” by poor electronic and ionic conductivity. While the problems with low electron conductivity are partially solved by carbon coating and further by doping or by downsizing the active particles to nanoscale dimensions, poor ionic conductivity is still an issue. To develop colloidally synthesized LiFePO4 nanocrystals (NCs) optimized for high rate applications, we propose here a surface treatment of the NCs. The particles as delivered from the synthesis have a surface passivated with long chain organic surfactants, and therefore can be dispersed only in aprotic solvents such as chloroform or toluene. Glucose that is commonly used as carbon source for carbon-coating procedure is not soluble in these solvents, but it can be dissolved in water. In order to make the NCs hydrophilic, we treated them with lithium hexafluorophosphate (LiPF6), which removes the surfactant ligand shell while preserving the structural and morphological properties of the NCs. Only a roughening of the edges of NCs was observed due to a partial etching of their surface. Electrodes prepared from these platelet NCs (after carbon coating) delivered a capacity of ∼155 mAh/g, ∼135 mAh/g, and ∼125 mAh/g, at 1 C, 5 C, and 10 C, respectively, with significant capacity retention and remarkable rate capability. For example, at 61 C (10.3 A/g), a capacity of ∼70 mAh/g was obtained, and at 122 C (20.7 A/g), the capacity was ∼30 mAh/g. The rate capability and the ease of scalability in the preparation of these surface-treated nanoplatelets make them highly suitable as electrodes in Li-ion batteries. PMID:25372361

  16. Study of poly (3-hexylthiophene) conducting polymer thin film micro-sensor for hydrazine vapor detection

    NASA Astrophysics Data System (ADS)

    Yang, Hong

    This dissertation discussed the construction and investigation of a poly (3-hexylthiophene) conducting polymer based thin film micro-sensor for a real-time detection of hydrazine vapor at ambient pressure. A type of low cost, small size, passive poly (3-hexylthiophene) thin film micro-sensor was designed and fabricated. The micro-sensor platform consisted of a rectangular shaped inert substrate and gold interdigited electrode pairs. A layer of poly (3-hexylthiophene) thin film was coated onto the sensor platform using a spin coating method, and nitrosonium hexafluorophosphate (NOPF6) was used to dope the poly (3-hexylthiophene) thin film to increase its electrical conductivity and form the finished sensor. The basic responses of the sensor to hydrazine vapor were experimentally investigated. The primary results showed that the sensor responded to hydrazine vapor in less than a few seconds; attained orders of magnitude change in normalized resistance during hydrazine exposure, and was not easily saturated. The interaction between the hydrazine gas molecules and doped poly (3-hexylthiophene) thin film was studied. The plausible mechanism was determined as: Charge carriers inside the doped poly (3-hexylthiophene) thin film were depleted during the oxidation-reduction chemical reaction between the hydrazine vapor and polymer film, resulting a reduction in the polymer film's electrical conductivity. Experiments were also conducted to find out the effects of hydrazine concentration, poly (3-hexylthiophene) thin film thickness, sensor storage time, environment temperature, and environment humidity on the sensor's performance. The response rate of the sensor under different sensing conditions was calculated and discussed. A diffusion-reaction model was applied to simulate the interaction between hydrazine molecules and doped poly (3-hexylthiophene) thin film. The profiles of hydrazine gas diffusion and positive charge carrier neutralization in the polymer film were

  17. Ionothermal synthesis of open-framework metal phosphates with a Kagome lattice network exhibiting canted anti-ferromagnetism

    SciTech Connect

    Wang, Guangmei; Valldor, Martin; Mallick, Bert; Mudring, Anja-Verena

    2014-01-01

    Four open-framework transition-metal phosphates; (NH4)2Co3(HPO4)2F4 (1), (NH4)Co3(HPO4)2(H2PO4)F2 (2), KCo3(HPO4)2(H2PO4)F2 (3), and KFe3(HPO4)2(H2PO4)F2 (4); are prepared by ionothermal synthesis using pyridinium hexafluorophosphate as the ionic liquid. Single-crystal X-ray diffraction analyses reveal that the four compounds contain cobalt/iron–oxygen/fluoride layers with Kagomé topology composed of interlinked face-sharing MO3F3/MO4F2 octahedra. PO3OH pseudo-tetrahedral groups augment the [M3O6F4] (1)/[M3O8F2] layers on both sides to give M3(HPO4)2F4 (1) and M3(HPO4)2F2 (2–4) layers. These layers are stacked along the a axis in a sequence AA…, resulting in the formation of a layer structure for (NH4)2Co3(HPO4)2F4(1). In NH4Co3(HPO4)2(H2PO4)F2 and KM3(HPO4)2(H2PO4)F2, the M3(HPO4)2F2 layers are stacked along the a axis in a sequence AAi… and are connected by [PO3(OH)] tetrahedra, giving rise to a 3-D open framework structure with 10-ring channels along the [001] direction. The negative charges of the inorganic framework are balanced by K+/NH4+ ions located within the channels. The magnetic transition metal cations themselves form layers with stair-case Kagomé topology. Magnetic susceptibility and magnetization measurements reveal that all four compounds exhibit a canted anti-ferromagnetic ground state (Tc = 10 or 13 K for Co and Tc = 27 K for Fe) with different canting angles. The full orbital moment is observed for both Co2+ and Fe2+.

  18. Synthesis and relative stability of a series of compounds of type [Fe(II)(bztpen)X]+, where bztpen=pentadentate ligand, N5, and X-=monodentate anion.

    PubMed

    Ortega-Villar, Norma; Ugalde-Saldívar, Víctor M; Muñoz, M Carmen; Ortiz-Frade, Luis A; Alvarado-Rodríguez, José G; Real, José A; Moreno-Esparza, Rafael

    2007-09-03

    The structural and solution characterization of novel Fe(II) compounds of the general formula [Fe(bztpen)X]PF6 and [Fe(bztpen)CH3CN](PF6)2 is presented, where bztpen is the pentadentate ligand N-benzyl-N,N',N'-tris(2-methylpyridyl)ethylenediamine and X- is a monodentate ligand. All complexes were characterized in solution and in the solid state, employing the usual techniques and single-crystal X-ray diffraction. The results obtained are discussed in terms of the existing information for some previously reported analogous compounds to arrive at a rationalization regarding the influence of a variation in the coordination environment of all compounds and to evaluate their relative stability. The observed magnetic response in the solid state is paramagnetic in the entire temperature range for the Cl-, Br-, I-, OCN-, and SCN- derivatives, while the N(CN)2-, CH3CN, and CN- derivatives are diamagnetic. The diamagnetic character of these last two compounds is confirmed in acetonitrile solution, while a spin transition step is observed for the N(CN)2- derivative. Diffraction data for all compounds as hexafluorophosphates shows that the I-, Br-, and OCN- derivatives crystallize in the orthorhombic space group Pbca, while the CN-, SCN-, and CH3CN compounds crystallize in the triclinic space group P. Average bond lengths and the trigonal distortion parameter can be correlated to the observed magnetic susceptibility depending on the coordinated monodentate ligand. Solution measurements of electronic properties for the compounds follow the trend established by the spectrochemical series. The relative stability of the Fe(II) complexes can be established in terms of the percentage of dissociation from the voltammetry and conductivity results, which are consistent with those obtained spectrophotometrically, mainly, the larger stability for the CN- derivative and the lower for the I- derivative. The redox potential and percentage of dissociation values allow for the estimation of

  19. Li-Ion Cells Employing Electrolytes With Methyl Propionate and Ethyl Butyrate Co-Solvents

    NASA Technical Reports Server (NTRS)

    Smart, Marshall C.; Bugga, Ratnakumar V.

    2011-01-01

    Future NASA missions aimed at exploring Mars and the outer planets require rechargeable batteries that can operate at low temperatures to satisfy the requirements of such applications as landers, rovers, and penetrators. A number of terrestrial applications, such as hybrid electric vehicles (HEVs) and electric vehicles (EVs) also require energy storage devices that can operate over a wide temperature range (i.e., -40 to +70 C), while still providing high power capability and long life. Currently, the state-of-the-art lithium-ion system has been demonstrated to operate over a wide range of temperatures (-30 to +40 C); however, the rate capability at the lower temperatures is very poor. These limitations at very low temperatures are due to poor electrolyte conductivity, poor lithium intercalation kinetics over the electrode surface layers, and poor ionic diffusion in the electrode bulk. Two wide-operating-temperature-range electrolytes have been developed based on advances involving lithium hexafluorophosphate-based solutions in carbonate and carbonate + ester solvent blends, which have been further optimized in the context of the technology and targeted applications. The approaches employed include further optimization of electrolytes containing methyl propionate (MP) and ethyl butyrate (EB), which are effective co-solvents, to widen the operating temperature range beyond the baseline systems. Attention was focused on further optimizing ester-based electrolyte formulations that have exhibited the best performance at temperatures ranging from -60 to +60 C, with an emphasis upon improving the rate capability at -20 to -40 C. This was accomplished by increasing electrolyte salt concentration to 1.20M and increasing the ester content to 60 percent by volume to increase the ionic conductivity at low temperatures. Two JPL-developed electrolytes 1.20M LiPF6 in EC+EMC+MP (20:20:60 v/v %) and 1.20M LiPF6 in EC+EMC+EB (20:20:60 v/v %) operate effectively over a wide

  20. Molecular dynamics simulations of the first charge of a Li-ion-Si-anode nanobattery.

    PubMed

    Galvez-Aranda, Diego E; Ponce, Victor; Seminario, Jorge M

    2017-04-01

    Rechargeable lithium-ion batteries are the most popular devices for energy storage but still a lot of research needs to be done to improve their cycling and storage capacity. Silicon has been proposed as an anode material because of its large theoretical capacity of ∼3600 mAh/g. Therefore, focus is needed on the lithiation process of silicon anodes where it is known that the anode increases its volume more than 300%, producing cracking and other damages. We performed molecular dynamics atomistic simulations to study the swelling, alloying, and amorphization of a silicon nanocrystal anode in a full nanobattery model during the first charging cycle. A dissolved salt of lithium hexafluorophosphate in ethylene carbonate was chosen as the electrolyte solution and lithium cobalt oxide as cathode. External electric fields are applied to emulate the charging, causing the migration of the Li-ions from the cathode to the anode, by drifting through the electrolyte solution, thus converting pristine Si gradually into Li14Si5 when fully lithiated. When the electric field is applied to the nanobattery, the temperature never exceeds 360 K due to a temperature control imposed resembling a cooling mechanism. The volume of the anode increases with the amorphization of the silicon as the external field is applied by creating a layer of LiSi alloy between the electrolyte and the silicon nanocrystal and then, at the arrival of more Li-ions changing to an alloy, where the drift velocity of Li-ions is greater than the velocity in the initial nanocrystal structure. Charge neutrality is maintained by concerted complementary reduction-oxidation reactions at the anode and cathode, respectively. In addition, the nanobattery model developed here can be used to study charge mobility, current density, conductance and resistivity, among several other properties of several candidate materials for rechargeable batteries and constitutes the initial point for further studies on the formation of the

  1. NafionxAE-based polymer actuators with ionic liquids as solvent incorporated at room temperature

    NASA Astrophysics Data System (ADS)

    Kikuchi, Kunitomo; Tsuchitani, Shigeki

    2009-09-01

    Nafion®-based ionic polymer-metal composites (IPMCs), with ionic liquids as solvent, were fabricated by exchanging counterions to ionic liquids at room temperature. Ion exchange is performed by only immersing IPMC in a mixture of de-ionized water and ionic liquids at room temperature for 48 h. The fabricated IPMCs exhibited a bending curvature the same as or larger than that of conventional IPMCs with ionic liquids, formed by ion exchange to ionic liquids at an elevated temperature up to about 100 °C, and also had long-term stability in operation in air, with a fluctuation smaller than 21% in bending curvature during a 180 min operation. The effective ion exchange to ionic liquids in the present method is probably due to an increase in diffusion speed of ionic liquids into IPMC by adsorption of water in a Nafion® membrane. It is a surprise that among IPMCs with ionic liquids 1-ethyl-3-methyl-imidazolium tetrafluoroborate, 1-buthyl-3-methyl-imidazolium tetrafluoroborate (BMIBF4), and 1-buthyl-3-methyl-imidazolium hexafluorophosphate (BMIPF6), IPMC with water-insoluble BMIPF6 exhibited a larger bending curvature than that IPMC with water-miscible BMIBF4. This might be due to effective incorporation of BMIPF6 into IPMC, since BMIPF6 has a higher affinity with IPMC than with water in the mixture of water and BMIPF6. From measurements of complex impedance and step voltage response of the driving current of IPMCs with ionic liquid, they are expressed by an equivalent circuit of a parallel combination of a serial circuit of membrane resistance of Nafion® and electric double layer capacitance at metal electrodes, with membrane capacitance of Nafion®, in a frequency range higher than about 0.1 Hz. The difference in magnitude of bending curvature in three kinds of IPMCs with ionic liquids is mainly due to the difference in bending response speed coming from the difference in the membrane resistance.

  2. Gold-ionic liquid nanofluids with preferably tribological properties and thermal conductivity

    PubMed Central

    2011-01-01

    Gold/1-butyl-3-methylimidazolium hexafluorophosphate (Au/[Bmim][PF6]) nanofluids containing different stabilizing agents were fabricated by a facile one-step chemical reduction method, of which the nanofluids stabilized by cetyltrimethylammonium bromide (CTABr) exhibited ultrahighly thermodynamic stability. The transmission electron microscopy, UV-visible absorption, Fourier transform infrared, and X-ray photoelectron characterizations were conducted to reveal the stable mechanism. Then, the tribological properties of these ionic liquid (IL)-based gold nanofluids were first investigated in more detail. In comparison with pure [Bmim][PF6] and the nanofluids possessing poor stability, the nanofluids with high stability exhibited much better friction-reduction and anti-wear properties. For instance, the friction coefficient and wear volume lubricated by the nanofluid with rather low volumetric concentration (1.02 × 10-3%) stabilized by CTABr under 800 N are 13.8 and 45.4% lower than that of pure [Bmim][PF6], confirming that soft Au nanoparticles (Au NPs) also can be excellent additives for high performance lubricants especially under high loads. Moreover, the thermal conductivity (TC) of the stable nanofluids with three volumetric fraction (2.55 × 10-4, 5.1 × 10-4, and 1.02 × 10-3%) was also measured by a transient hot wire method as a function of temperature (33 to 81°C). The results indicate that the TC of the nanofluid (1.02 × 10-3%) is 13.1% higher than that of [Bmim][PF6] at 81°C but no obvious variation at 33°C. The conspicuously temperature-dependent and greatly enhanced TC of Au/[Bmim][PF6] nanofluids stabilized by CTABr could be attributed to micro-convection caused by the Brownian motion of Au NPs. Our results should open new avenues to utilize Au NPs and ILs in tribology and the high-temperature heat transfer field. PMID:21711789

  3. How strong is hydrogen bonding in ionic liquids? Combined X-ray crystallographic, infrared/Raman spectroscopic, and density functional theory study.

    PubMed

    Katsyuba, Sergey A; Vener, Mikhail V; Zvereva, Elena E; Fei, Zhaofu; Scopelliti, Rosario; Laurenczy, Gabor; Yan, Ning; Paunescu, Emilia; Dyson, Paul J

    2013-08-01

    Hydrogen bonding in ionic liquids based on the 1-(2'-hydroxylethyl)-3-methylimidazolium cation ([C₂OHmim](+)) and various anions ([A](-)) of differing H-bond acceptor strength, viz. hexafluorophosphate [PF6](-), tetrafluoroborate [BF₄](-), bis(trifluoromethanesulfonimide) [Tf₂N](-), trifluoromethylsulfonate [OTf](-), and trifluoroacetate [TFA](-), was studied by a range of spectroscopic and computational techniques and, in the case of [C₂OHmim][PF6], by single crystal X-ray diffraction. The first quantitative estimates of the energy (E(HB)) and the enthalpy (-ΔH(HB)) of H-bonds in bulk ILs were obtained from a theoretical analysis of the solid-state electron-density map of crystalline [C₂OHmim][PF6] and an analysis of the IR spectra in crystal and liquid samples. E(HB) for OH···[PF6](-) H-bonds amounts to ~3.4-3.8 kcal·mol(-1), whereas weaker H-bonds (2.8-3.1 kcal·mol(-1)) are formed between aromatic C2H group of imidazolium ring and the [PF6](-) anion. The enthalpy of the OH···[A](-) H-bonds follows the order: [PF6] (2.4 kcal·mol(-1)) < [BF₄] (3.3 kcal·mol(-1)) < [Tf₂N] (3.4 kcal·mol(-1)) < [OTf] (4.7 kcal·mol(-1)l) < [TFA] (6.2 kcal·mol(-1)). The formation of aggregates of self-associated [C₂OHmim](+) cations is present in liquid [C₂OHmim][PF6], [C₂OHmim][BF₄], and [C₂OHmim][Tf₂N], with the energy of the OH···OH H-bonds amounting to ~6 kcal·mol(-1). Multiple secondary interactions in the bulk ILs influence their structure, vibrational spectra, and H-bond strength. In particular, these interactions can blue-shift the stretching frequencies of the CH groups of the imidazolium ring in spite of red-shifting CH···[A](-) H-bonds. They also weaken the H-bonding in the IL relative to the isolated ion pairs, with these anticooperative effects amounting to ca. 50% of the E(HB) value.

  4. Synthesis of Metal Nanoparticles and Metal Fluoride Nanoparticles from Metal Amidinate Precursors in 1‐Butyl‐3‐Methylimidazolium Ionic Liquids and Propylene Carbonate

    PubMed Central

    Schütte, Kai; Barthel, Juri; Endres, Manuel; Siebels, Marvin; Smarsly, Bernd M.; Yue, Junpei

    2016-01-01

    Abstract Decomposition of transition‐metal amidinates [M{MeC(NiPr)2}n] [M(AMD)n; M=MnII, FeII, CoII, NiII, n=2; CuI, n=1) induced by microwave heating in the ionic liquids (ILs) 1‐butyl‐3‐methylimidazolium tetrafluoroborate ([BMIm][BF4]), 1‐butyl‐3‐methylimidazolium hexafluorophosphate ([BMIm][PF6]), 1‐butyl‐3‐methylimidazolium trifluoromethanesulfonate (triflate) ([BMIm][TfO]), and 1‐butyl‐3‐methylimidazolium tosylate ([BMIm][Tos]) or in propylene carbonate (PC) gives transition‐metal nanoparticles (M‐NPs) in non‐fluorous media (e.g. [BMIm][Tos] and PC) or metal fluoride nanoparticles (MF2‐NPs) for M=Mn, Fe, and Co in [BMIm][BF4]. FeF2‐NPs can be prepared upon Fe(AMD)2 decomposition in [BMIm][BF4], [BMIm][PF6], and [BMIm][TfO]. The nanoparticles are stable in the absence of capping ligands (surfactants) for more than 6 weeks. The crystalline phases of the metal or metal fluoride synthesized in [BMIm][BF4] were identified by powder X‐ray diffraction (PXRD) to exclusively Ni‐ and Cu‐NPs or to solely MF2‐NPs for M=Mn, Fe, and Co. The size and size dispersion of the nanoparticles were determined by transmission electron microscopy (TEM) to an average diameter of 2(±2) to 14(±4) nm for the M‐NPs, except for the Cu‐NPs in PC, which were 51(±8) nm. The MF2‐NPs from [BMIm][BF4] were 15(±4) to 65(±18) nm. The average diameter from TEM is in fair agreement with the size evaluated from PXRD with the Scherrer equation. The characterization was complemented by energy‐dispersive X‐ray spectroscopy (EDX). Electrochemical investigations of the CoF2‐NPs as cathode materials for lithium‐ion batteries were simply evaluated by galvanostatic charge/discharge profiles, and the results indicated that the reversible capacity of the CoF2‐NPs was much lower than the theoretical value, which may have originated from the complex conversion reaction mechanism and residue on the surface of the nanoparticles. PMID:28168159

  5. How ion properties determine the stability of a lipase enzyme in ionic liquids: a molecular dynamics study.

    PubMed

    Klähn, Marco; Lim, Geraldine S; Wu, Ping

    2011-11-07

    The influence of eight different ionic liquid (IL) solvents on the stability of the lipase Candida antarctica lipase B (CAL-B) is investigated with molecular dynamics (MD) simulations. Considered ILs contain cations that are based either on imidazolium or guanidinium as well as nitrate, tetrafluoroborate or hexafluorophosphate anions. Partial unfolding of CAL-B is observed during high-temperature MD simulations and related changes of CAL-B regarding its radius of gyration, surface area, secondary structure, amount of solvent close to the backbone and interaction strength with the ILs are evaluated. CAL-B stability is influenced primarily by anions in the order NO(3)(-)≪ BF(4)(-) < PF(6)(-) of increasing stability, which agrees with experiments. Cations influence protein stability less than anions but still substantially. Long decyl side chains, polar methoxy groups and guanidinium-based cations destabilize CAL-B more than short methyl groups, other non-polar groups and imidazolium-based cations, respectively. Two distinct causes for CAL-B destabilization are identified: a destabilization of the protein surface is facilitated mostly by strong Coulomb interactions of CAL-B with anions that exhibit a localized charge and strong polarization as well as with polar cation groups. Surface instability is characterized by an unraveling of α-helices and an increase of surface area, radius of gyration and protein-IL total interaction strength of CAL-B, all of which describe a destabilization of the folded protein state. On the other hand, a destabilization of the protein core is facilitated when direct core-IL interactions are feasible. This is the case when long alkyl chains are involved or when particularly hydrophobic ILs induce major conformational changes that enable ILs direct access to the protein core. This core instability is characterized by a disintegration of β-sheets, diffusion of ions into CAL-B and increasing protein-IL van der Waals interactions. This

  6. Ionothermal synthesis of open-framework metal phosphates with a Kagomé lattice network exhibiting canted anti-ferromagnetism†Electronic supplementary information (ESI) available: Cif files, atomic parameters, X-ray diffraction patterns, IR spectra, TG curves, and thermal ellipsoid plot and atomic label schemes of compound 1-4. See DOI: 10.1039/c4tc00290cClick here for additional data file.

    PubMed

    Wang, Guangmei; Valldor, Martin; Mallick, Bert; Mudring, Anja-Verena

    2014-09-21

    Four open-framework transition-metal phosphates; (NH4)2Co3(HPO4)2F4 (1), (NH4)Co3(HPO4)2(H2PO4)F2 (2), KCo3(HPO4)2(H2PO4)F2 (3), and KFe3(HPO4)2(H2PO4)F2 (4); are prepared by ionothermal synthesis using pyridinium hexafluorophosphate as the ionic liquid. Single-crystal X-ray diffraction analyses reveal that the four compounds contain cobalt/iron-oxygen/fluoride layers with Kagomé topology composed of interlinked face-sharing MO3F3/MO4F2 octahedra. PO3OH pseudo-tetrahedral groups augment the [M3O6F4] (1)/[M3O8F2] layers on both sides to give M3(HPO4)2F4 (1) and M3(HPO4)2F2 (2-4) layers. These layers are stacked along the a axis in a sequence AA…, resulting in the formation of a layer structure for (NH4)2Co3(HPO4)2F4(1). In NH4Co3(HPO4)2(H2PO4)F2 and KM3(HPO4)2(H2PO4)F2, the M3(HPO4)2F2 layers are stacked along the a axis in a sequence AA i … and are connected by [PO3(OH)] tetrahedra, giving rise to a 3-D open framework structure with 10-ring channels along the [001] direction. The negative charges of the inorganic framework are balanced by K(+)/NH4(+) ions located within the channels. The magnetic transition metal cations themselves form layers with stair-case Kagomé topology. Magnetic susceptibility and magnetization measurements reveal that all four compounds exhibit a canted anti-ferromagnetic ground state (Tc = 10 or 13 K for Co and Tc = 27 K for Fe) with different canting angles. The full orbital moment is observed for both Co(2+) and Fe(2+).

  7. Ionic liquids for nano- and microstructures preparation. Part 2: Application in synthesis.

    PubMed

    Łuczak, Justyna; Paszkiewicz, Marta; Krukowska, Anna; Malankowska, Anna; Zaleska-Medynska, Adriana

    2016-01-01

    Ionic liquids (ILs) are widely applied to prepare metal nanoparticles and 3D semiconductor microparticles. Generally, they serve as a structuring agent or reaction medium (solvent), however it was also demonstrated that ILs can play a role of a co-solvent, metal precursor, reducing as well as surface modifying agent. The crucial role and possible types of interactions between ILs and growing particles have been presented in the Part 1 of this review paper. Part 2 of the paper gives a comprehensive overview of recent experimental studies dealing with application of ionic liquids for preparation of metal and semiconductor based nano- and microparticles. A wide spectrum of preparation routes using ionic liquids is presented, including precipitation, sol-gel technique, hydrothermal method, nanocasting and ray-mediated methods (microwave, ultrasound, UV-radiation and γ-radiation). It was found that ionic liquids formed of a 1-butyl-3-methylimidazolium [BMIM] combined with tetrafluoroborate [BF4], hexafluorophosphate [PF6], and bis(trifluoromethanesulfonyl)imide [Tf2N] are the most often used ILs in the synthesis of nano- and microparticles, due to their low melting temperature, low viscosity and good transportation properties. Nevertheless, examples of other IL classes with intrinsic nanoparticles stabilizing abilities such as phosphonium and ammonium derivatives are also presented. Experimental data revealed that structure of ILs (both anion and cation type) affects the size and shape of formed metal particles, and in some cases may even determine possibility of particles formation. The nature of the metal precursor determines its affinity to polar or nonpolar domains of ionic liquid, and therefore, the size of the nanoparticles depends on the size of these regions. Ability of ionic liquids to form varied extended interactions with particle precursor as well as other compounds presented in the reaction media (water, organic solvents etc.) provides nano- and

  8. The Roles of Molecular Structure and Effective Optical Symmetry in Evolving Dipolar Chromophoric Building Blocks to Potent Octopolar NLO Chromophores

    PubMed Central

    Ishizuka, Tomoya; Sinks, Louise E.; Song, Kai; Hung, Sheng-Ting; Nayak, Animesh; Clays, Koen; Therien, Michael J.

    2011-01-01

    A series of mono-, bis-, tris-, and tetrakis-(porphinato)zinc(II) (PZn)-elaborated ruthenium(II) bis(terpyridine) (Ru) complexes has been synthesized in which an ethyne unit connects the macrocycle meso carbon atom to terpyridyl (tpy) 4-, 4′-, and 4″- positions. These supermolecular chromophores, based on the ruthenium(II) [5-(4′-ethynyl-(2,2′;6′,2″-terpyridinyl))-10,20-bis(2′,6′-bis(3,3-dimethyl-1-butyloxy)phenyl)porphinato]zinc(II)-(2,2′;6′,2″-terpyridine)2+ bis-hexafluorophosphate (RuPZn) archetype, evince strong mixing of the PZn-based oscillator strength with ruthenium terpyridyl charge resonance bands. Potentiometric and linear absorption spectroscopic data indicate that for structures in which multiple PZn moieties are linked via ethynes to a [Ru(tpy)2]2+ core, little electronic coupling is manifest between PZn units, regardless of whether they are located on the same or opposite tpy ligand. Congruent with these experiments, pump-probe transient absorption studies suggest that the individual RuPZn fragments of these structures exhibit, at best, only modest excited-state electronic interactions that derive from factors other than the dipole-dipole interactions of these strong oscillators; this approximate independent character of the component RuPZn oscillators enables fabrication of NLO multipoles with extraordinary hyperpolarizabilities. Dynamic hyperpolarizability (βλ) values and depolarization ratios (ρ) were determined from hyper-Rayleigh light scattering (HRS) measurements carried out at an incident irradiation wavelength (λinc) of 1300 nm. The depolarization ratio data provide an experimental measure of chromophore optical symmetry; appropriate coupling of multiple charge-transfer oscillators produces structures having enormous averaged hyperpolarizabilities (βHRS values), while evolving the effective chromophore symmetry from purely dipolar (e.g., Ru(tpy)[4-(Znporphyrin)ethynyl-tpy](PF6)2, βHRS = 1280 × 10−30 esu, ρ = 3

  9. Electrospun Nanofiber-Coated Membrane Separators for Lithium-Ion Batteries

    NASA Astrophysics Data System (ADS)

    Lee, Hun

    separator membranes and the nanoscale fibrous polymer coatings. The polyolefin microporous membranes serve as the supporting substrate which provides the required mechanical strength for the assembling process of lithium-ion batteries. The electrospun nanofiber coatings improve the wettability of the composite membrane separators to the liquid electrolyte, which is desirable for the lithium-ion batteries with high kinetics and good cycling performance. The results show that the nanofiber-coated membranes have enhanced adhesion properties to the battery electrode which can help prevent the formation of undesirable gaps between the separators and electrodes during prolonged charge-discharge cycles, especially in large-format batteries. The improvement on adhesive properties of nanofiber-coated membranes was evaluated by peel test. Nanofiber coatings applied to polyolefin membrane substrates improve the adhesion of separator membranes to battery electrodes. Electrolyte uptakes, ionic conductivities and interfacial resistances of the nanofiber-coated membrane separators were studied by soaking the membrane separators with a liquid electrolyte solution of 1 M lithium hexafluorophosphate dissolved in ethylene carbonate/dimethylcarbonate/ethylmethyl carbonate (1:1:1 vol). The nanofiber coatings on the surface of the membrane substrates increase the electrolyte uptake capacity due to the high surface area and capillary effect of nanofibers. The nanofiber-coated membranes soaked in the liquid electrolyte solution exhibit high ionic conductivities and low interfacial resistances to the lithium electrode. The cells containing LiFePO 4 cathode and the nanofiber-coated membranes as the separator show high discharge specific capacities and good cycling stability at room temperature. The nanofiber coatings on the membrane substrates contribute to high ionic conductivity and good electrochemical performance in lithium-ion batteries. Therefore, these nanofiber-coated composite membranes can

  10. The roles of molecular structure and effective optical symmetry in evolving dipolar chromophoric building blocks to potent octopolar nonlinear optical chromophores.

    PubMed

    Ishizuka, Tomoya; Sinks, Louise E; Song, Kai; Hung, Sheng-Ting; Nayak, Animesh; Clays, Koen; Therien, Michael J

    2011-03-09

    A series of mono-, bis-, tris-, and tetrakis(porphinato)zinc(II) (PZn)-elaborated ruthenium(II) bis(terpyridine) (Ru) complexes have been synthesized in which an ethyne unit connects the macrocycle meso carbon atom to terpyridyl (tpy) 4-, 4'-, and 4''-positions. These supermolecular chromophores, based on the ruthenium(II) [5-(4'-ethynyl-(2,2';6',2''-terpyridinyl))-10,20-bis(2',6'-bis(3,3-dimethyl-1-butyloxy)phenyl)porphinato]zinc(II)-(2,2';6',2''-terpyridine)(2+) bis-hexafluorophosphate (RuPZn) archetype, evince strong mixing of the PZn-based oscillator strength with ruthenium terpyridyl charge resonance bands. Potentiometric and linear absorption spectroscopic data indicate that for structures in which multiple PZn moieties are linked via ethynes to a [Ru(tpy)(2)](2+) core, little electronic coupling is manifest between PZn units, regardless of whether they are located on the same or opposite tpy ligand. Congruent with these experiments, pump-probe transient absorption studies suggest that the individual RuPZn fragments of these structures exhibit, at best, only modest excited-state electronic interactions that derive from factors other than the dipole-dipole interactions of these strong oscillators; this approximate independent character of the component RuPZn oscillators enables fabrication of nonlinear optical (NLO) multipoles with extraordinary hyperpolarizabilities. Dynamic hyperpolarizability (β(λ)) values and depolarization ratios (ρ) were determined from hyper-Rayleigh light scattering (HRS) measurements carried out at an incident irradiation wavelength (λ(inc)) of 1300 nm. The depolarization ratio data provide an experimental measure of chromophore optical symmetry; appropriate coupling of multiple charge-transfer oscillators produces structures having enormous averaged hyperpolarizabilities (β(HRS) values), while evolving the effective chromophore symmetry from purely dipolar (e.g., Ru(tpy)[4-(Zn-porphyrin)ethynyl-tpy](PF(6))(2), β(HRS) = 1280

  11. Molecular physics of electrical double layers in electrochemical capacitors

    NASA Astrophysics Data System (ADS)

    Feng, Guang

    tetraethylammonium tetrafluoroborate (TEABF4) in the aprotic solvent of acetonitrile (ACN). Firstly, the solvation of TEA+ and BF4 - ions is found to be much weaker than that of small inorganic ions. This characteristic accounts for the rich structure of EDLs near the electrodes. In particular, near charged electrodes, the ion distribution cannot be explained by the traditional EDL models. Secondly, the computed capacitances of EDLs agree well with those inferred from experimental measurements. Finally, we probed the dynamics of EDLs in organic electrolytes by analyzing the rotational dynamics of solvent and the self diffusion coefficients of ion/solvent. For the ILs, we performed the MD simulations of EDLs at the interface between an IL of 1-butyl-3-methylimidazolium nitrate ([BMIM][NO3]) and planar electrodes. The results revealed that the structure of the EDL is significantly affected by the liquid nature of the IL, the short-range ion--electrode and ion--ion interactions, and the charge delocalization of ions. We showed that the differential capacitance is a quantitative measure of the response of the EDL structure to a change of electrode surface charge density, and the concave-shaped capacitance--potential (C--V ) curve is in good agreement with that in the literature. To further acquire the theoretical understanding of EDLs in ILs, we investigated the effects of ion size and electrode curvature on the EDLs in ILs of 1-butyl-3-methylimidazolium chloride ([BMIM][Cl]) and 1-butyl-3-methylimidazolium hexafluorophosphate ([BMIM][PF6]). The results indicated that the ion size considerably affects the ion distribution and orientational structure of EDLs, and the EDL capacitances follow a certain order of the ion size. It was also found that the EDL capacitance increases as the electrode curvature increases. Based on the insights gained from the EDL structure and capacitance, a "Multiple Ion Layers with Overscreening" (MILO) model was proposed for EDLs in ILs. The capacitance

  12. Quantification of Electrochemical Nanoscale Processes in Lithium Batteries By OperandoEC-(S)TEM

    SciTech Connect

    Mehdi, Beata L.; Qian, Jiangfeng; Nasybulin, Eduard; Welch, David A.; Park, Chiwoo; Faller, Roland; Mehta, Hardeep S.; Henderson, Wesley A.; Xu, Wu; Evans, James E.; Liu, Jun; Zhang, Jiguang; Mueller, Karl T.; Browning, Nigel D.

    2015-07-27

    Lithium (Li)-ion batteries are currently used for a wide variety of portable electronic devices, electric vehicles and renewable energy applications. In addition, extensive worldwide research efforts are now being devoted to more advanced “beyond Li-ion” battery chemistries - such as lithium-sulfur (Li-S) and lithium-air (Li-O2) - in which the carbon anode is replaced with Li metal. However, the practical application of Li metal anode systems has been highly problematic. The main challenges involve controlling the formation of a solid-electrolyte interphase (SEI) layer and the suppression of Li dendrite growth during the charge/discharge process (achieving “dendrite-free” cycling). The SEI layer formation continuously consumes the electrolyte components creating highly resistive layer, which leads to the rapid decrease of cycling performance and degradation of the Li anode. The growth of Li metal dendrites at the anode contributes to rapid capacity fading (the presence of “dead Li” created during the discharge leads to an increased overpotential) and, in the case of continuous growth, leads to internal short circuits and extreme safety issues. Here we demonstrate the application of an operando electrochemical scanning transmission electron microscopy (ec-(S)TEM) cell to study the SEI layer formation and the initial stages of Li dendrite growth - the goal is to develop a mechanism for mitigating the degradation processes and increasing safety. Bright field (BF) STEM images in Figure 1 A-C show Li metal deposition and dissolution processes at the interface between the Pt working electrode and the lithium hexafluorophosphate (LiPF6) in propylene carbonate (PC) electrolyte during three charge/discharge cycles. A contrast reversal caused by Li metal being lighter/less dense than surrounding electrolyte (Li appears brighter than the background in BF STEM images) allows Li to be uniquely identified from the other components in the system - the only solid

  13. Molecular level energy and electron transfer processes at nanocrystalline titanium dioxide interfaces

    NASA Astrophysics Data System (ADS)

    Farzad, Fereshteh

    This thesis describes photo-induced molecular electron and energy transfer processes occurring at nanocrystalline semiconductor interfaces. The Introductory Chapter provides background and describes how these materials may be useful for solar energy conversion. In Chapter 2, results describing excitation of Ru(deeb)(bpy)2 2+, bis(2,2'-bipyridine)(2,2'-bipyridine-4,4 '-diethylester)ruthenium(II) hexafluorophosphate, bound to nanocrystalline TiO2 thin films, immersed in an acetonitrile bath are presented. The data indicates that light excitation forms predominately long-lived metal-to-ligand charge-transfer, MLCT, excited states under these conditions. Modeling of the data as a function of irradiance has been accomplished assuming parallel unimolecular and bimolecular excited state deactivation processes. The quantum yield for excited state formation depends on the excitation irradiance, consistent with triplet-triplet annihilation processes that occur with k > 1 x 108 s-1. Chapter 3 extends the work described in Chapter 2 to LiClO4 acetonitrile solutions. Li+ addition results in a red shift in the MLCT absorption and photoluminescence, PL, and a concentration dependent quenching of the PL intensity on TiO2. The Li+ induced spectroscopic changes were found to be reversible by varying the electrolyte composition. A second-order kinetic model quantified charge recombination transients. A model is proposed wherein Li+ ion adsorption stabilizes TiO2 acceptor states resulting in energetically more favorable interfacial electron transfer. The photophysical and photoelectrochemical properties of porous nanocrystalline anatase TiO2 electrodes modified with Ru(deeb)(bpy)2 2+, Os(deeb)(bpy)22+, and mixtures of both are described in Chapters 4 and 5. In regenerative solar cells with 0.5 M LiI/0.05 M I2 acetonitrile electrolyte, both compounds efficiently inject electrons into TiO2 producing monochromatic incident photon-to-current efficiencies (IPCE), IPCE (460 nm) = 0.70 + 0

  14. Determination of transport properties and optimization of lithium-ion batteries

    NASA Astrophysics Data System (ADS)

    Stewart, Sarah Grace

    We have adapted the method of restricted diffusion to measure diffusion coefficients in lithium-battery electrolytes using Ultra-Violent-Visible (UV-Vis) absorption. The use of UV-Vis absorption reduces the likelihood of side reactions. Here we describe the measurement of the diffusion coefficient in lithium-battery electrolytic solutions. The diffusion coefficient is seen to decrease with increasing concentration according to the following: D = 3.018·10-5 exp(-0.357c), for LiPF 6 in acetonitrile and D = 2.582·10-5 exp(-2.856c) for LiPF6 in EC:DEC (with D in cm2/s and c in moles per liter). This technique may be useful for any liquid solution with a UV-active species of D greater than 10-6 cm2/s. Activity coefficients were measured in concentration cell and melting-point-depression experiments. Results from concentration-cell experiments are presented for solutions of lithium hexafluorophosphate (LiPF6) in propylene carbonate (PC) as well as in a 1:1 by weight solution of ethylene carbonate (EC) and ethyl methyl carbonate (EMC). Heat capacity results are also presented. The thermodynamic factor of LiPF6 solutions in EC varies between ca. 1.33 and ca. 6.10 in the concentration range ca. 0.06 to 1.25 M (which appears to be a eutectic point). We show that the solutions of LiPF6 investigated are not ideal but that an assumption of ideality for these solutions may overestimate the specific energy of a lithium-ion cell by only 0.6%. The thermodynamic and transport properties that we have measured are used in a system model. We have used this model to optimize the design of an asymmetric-hybrid system. This technology attempts to bridge the gap in energy density between a battery and supercapacitor. In this system, the positive electrode stores charge through a reversible, nonfaradaic adsorption of anions on the surface. The negative electrode is nanostructured Li4Ti 5O12, which reversibly intercalates lithium. We use the properties that we have measured in a system