Science.gov

Sample records for 1-butyl-3-methyl imidazolium room

  1. Solubilities of carbon dioxide and oxygen in the ionic liquids methyl trioctyl ammonium bis(trifluoromethylsulfonyl)imide, 1-butyl-3-methyl imidazolium bis(trifluoromethylsulfonyl)imide, and 1-butyl-3-methyl imidazolium methyl sulfate.

    PubMed

    Bahadur, Indra; Osman, Khalid; Coquelet, Christophe; Naidoo, Paramespri; Ramjugernath, Deresh

    2015-01-29

    Ionic liquids (ILs) are being considered as solvents for gas absorption processes as they have the potential, in general, for improved efficiency of gas separations, as well as lower capital and operating costs compared to current commercial processes. In this study the solvent properties of ILs are investigated for use in the absorption of carbon dioxide (CO2) and oxygen (O2). The absorption of these gases in ILs was measured in the temperature range 303.15-333.15 K and at pressures up to 1.5 MPa by gravimetric analysis. The ILs used were methyl trioctyl ammonium bis (trifluoromethylsulfonyl) imide ([MOA][Tf2N]), 1-butyl-3-methyl imidazolium bis (trifluoromethylsulfonyl) imide ([BMIM][Tf2N]), and 1-butyl-3-methyl imidazolium methyl sulfate ([BMIM][MeSO4]). The measurement technique employed in this study is fast and accurate, and requires small quantities of solvent. The results indicated that absorption of both gases increased with a decrease in operating temperature and an increase in pressure. [MOA][Tf2N] had the highest CO2 and O2 solubility. [BMIM][Tf2N] was determined to have the highest selectivity for CO2 absorption. [BMIM][MeSO4] achieved the lowest CO2 absorption with a moderate O2 absorption, revealing this IL to be the least desirable for CO2 and O2 absorption. Calculation of Henry's law constants for all systems confirmed the deductions made from absorption data analysis. Calculation of enthalpy and entropy of absorption for each system revealed CO2 absorption in [MOA][Tf2N] to be the least sensitive to temperature increases. The absorption data was modeled using the generic Redlich-Kwong cubic equation of state (RK-EOS) coupled with a group contribution method.

  2. 1-Butyl-3-Methyl Imidazolium-based Ionic Liquids Explored as Potential Solvents for Lipid Processing

    USDA-ARS?s Scientific Manuscript database

    Due to global environmental concerns, there is increasing interest in replacing the volatile solvents currently used to process commodity plant lipids. Room-temperature molten salts are one type of media receiving great attention as a possible replacement of the typical organic solvent. Molten sal...

  3. Solvation of sodium chloride in the 1-butyl-3-methyl-imidazolium bis(trifluoromethylsulfonyl)imide ionic liquid: a molecular dynamics study.

    PubMed

    Sieffert, Nicolas; Wipff, Georges

    2007-06-28

    We report molecular dynamics studies on the solvation of sodium chloride in the 1-butyl-3-methyl-imidazolium bis(trifluoromethylsulfonyl)imide ionic liquid ([BMI][Tf2N] IL). We first consider the potential of mean force for dissociating a single Na+Cl- ion pair, showing that the latter prefers to be undissociated rather than dissociated (by ca. 9 kcal/mol), with a free energy barrier of ca. 5 kcal/mol (at d approximately 5.2 A) for the association process. The preference for Na+Cl- association is also observed from a 100 ns molecular dynamics simulation of a concentrated solution, where the Na+Cl- ions tend to form oligomers and microcrystals in the IL. Conversely, the simulation of Na13Cl14- and Na14Cl13+ cubic microcrystals (with, respectively, Cl- and Na+ at the vertices) does not lead to dissolution in the IL. Among these, Na14Cl13+ is found to be better solvated than Na13Cl14-, mainly due to the stronger Na+...Tf2N- interactions as compared to the Cl-...BMI+ interactions at the vertices of the cube. We finally consider the solid/liquid interface between the 100 face of NaCl and the IL, revealing that, in spite of its polar nature, the crystal surface is solvated by the less polar IL components (CF3(Tf2N) and butyl(BMI) groups) rather than by the polar ones (O(Tf2N) and imidazolium(BMI) ring). Specific ordering at the interface is described for both Tf2N- anions and BMI+ cations. In the first IL layer, the ions are rather parallel to the surface, whereas in the second "layer" they are more perpendicular. A similar IL structure is found at the surface of the all-neutral Na0Cl0 solid analogue, confirming that the solvation of the crystal is rather "apolar", due to the mismatch between the IL and the crystal ions. Several comparisons with water, methanol, or different BMI+-based ILs as solvents are presented, allowing us to better understand the specificity of the ionic liquid-NaCl interactions.

  4. Effects of 1-butyl-3-methyl imidazolium tetrafluoroborate ionic liquid on Triton X-100 aqueous micelles: solvent and rotational relaxation studies.

    PubMed

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

    2011-06-02

    The effect of added room-temperature ionic liquids on the nature of water molecules in the palisade layer of a Triton X-100 (TX-100) micelle has been investigated using solvation and rotational relaxation studies of coumarin 153 in the presence of different wt % of [bmim][BF(4)] and thus to understand the changes in micellar palisade layer, especially the entrapped water structures in the palisade layer. It has been observed that in the presence of added [bmim][BF(4)] the solvation dynamics becomes faster. It has previously been demonstrated (Behera et al. J. Chem. Phys.2007, 127, 184501) that in the present micellar systems, in the presence of [bmim][BF(4)] micellar size and aggregation number (N(agg)) decreases giving rise to more water molecules penetrating in to the micellar phase which results in increased microfluidity. In accordance with solvation dynamics results, fluorescence anisotropy studies also indicate an increased microfluidity for the palisade layer of the TX-100 micelle with the added [bmim][BF(4)]. Wobbling-in-cone analysis of the anisotropy data also supports this finding.

  5. Infrared studies of PVC-based electrolytes incorporated with lithium triflate and 1-butyl-3-methyl imidazolium trifluoromethanesulfonate as ionic liquid

    NASA Astrophysics Data System (ADS)

    Zulkepeli, Nik A. S. Nik; Winie, Tan; Subban, R. H. Y.

    2017-09-01

    In this work, 1-butyl-3-methylimidazolium trifluoromethanesulfonate (BMIMCF3SO3) is employed as ionic liquid in PVC-based polymer electrolyte system with lithium triflate (LiCF3SO3) as doping salt. The samples in film form were prepared by quantitatively varying the concentration of BMIMCF3SO3 to a fixed ratio of PVC-LiCF3SO3 using solution cast technique. The highest room temperature ionic conductivity of 1.120 × 10-7 Scm-1 was exhibited by PVC-LiCF3SO3-BMIMCF3SO3 containing 3 wt. % BMIMCF3SO3. FTIR spectra of the polymer electrolytes were examined to study the complexation of the PVC-based polymer electrolytes. Intensity of free ions, ion pairs, and ion aggregates were obtained from FTIR deconvolution in an attempt to correlate with ionic conductivity results. The intensity of free ions was found to be high for sample with 3 wt. % BMIMCF3SO3.

  6. 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.

  7. 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.

  8. Electrochemical behaviors of polymer composite electrolytes containing imidazolium-type room-temperature molten salts.

    PubMed

    Kim, Seok; Park, Soo-Jin

    2009-12-01

    The effects of room-temperature molten salt addition on electrochemical properties of polymer composite electrolytes (PCE) based on poly(ethylene oxide) (PEO) were studied. Alkyl-imidazolium salt, 1-butyl-3-methyl-imidazolium hexafluorophosphate (BMIPF6) could influence ion transference phenomena, resulting the change of ionic conductivity of PCE. The PCE containing 1.2 mole% BMIPF6 showed the slightly lower melting temperature than PEO-LiClO4. The PCE showed the highest ion conductivity of 2.9 * 10(-4) S/cm, which is one-order-of-magnitude higher value than the pristine sample. This is probably originated from the improved ion transference and slightly decreased crystallinity. Li ion transference number was increased to 0.55 and the stable electrochemical voltage limit was upgraded to approximately 4.3 V. Consequently, the ion conducting behaviors and the electrochemical stability had been improved by BMIPF6 addition.

  9. Morphology of poly(ethylene oxide) dissolved in a room temperature ionic liquid: a small angle neutron scattering study.

    PubMed

    Triolo, Alessandro; Russina, Olga; Keiderling, Uwe; Kohlbrecher, Joachim

    2006-02-02

    Solutions of deuterated poly(ethylene oxide) (d-PEO) in 1-butyl-3-methyl imidazolium tetrafluoroborate ([bmim][BF4]), a prototype room-temperature ionic liquid (RTIL), have been studied at room temperature over a range of polymer concentrations, using small angle neutron scattering (SANS), characterizing the conformation of PEO dissolved in RTILs. [bmim][BF4] behaves as a good solvent for d-PEO, which organizes in this solvent in non entangled random coils. These findings will help in optimizing the designing of microemulsions in these potentially environmentally friendly solvents.

  10. Effect of water on the solvent relaxation dynamics in an ionic liquid containing microemulsion of 1-butyl-3-methyl imidazolium tetrafluoroborate/TritonX-100/cyclohexane

    NASA Astrophysics Data System (ADS)

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

    2010-04-01

    The dynamics of solvent and rotational relaxation have been investigated in [bmim][BF 4]/TX-100/cyclohexane microemulsions with addition of water-using steady state and time-resolved fluorescence spectroscopy as a tool and coumarin 480 (C-480) as a fluorescence probe. The added water decreases the size of the microemulsions; consequently solvent relaxation time increases. The rotational relaxation time of C-480 in microemulsions is almost unchanged with increase in amount of water in microemulsions.

  11. Terahertz and Infrared Spectroscopy of Room-Temperature Imidazolium-Based Ionic Liquids.

    PubMed

    Yamada, Toshiki; Tominari, Yukihiro; Tanaka, Shukichi; Mizuno, Maya

    2015-12-24

    The terahertz- and infrared-frequency vibrational modes of various room-temperature imidazolium-based ionic liquids with molecular anions were examined extensively. We found that the molar-concentration-normalized absorption coefficient spectra in the low-wavenumber range for imidazolium cations with different alkyl-chain lengths were nearly identical for the same anion. Regarding the overall view of a wide range of imidazolium-based ionic liquids, we found that the reduced mass of the combination of an imidazolium-ring cation and the anion and the force constant play significant roles in determining the central frequency of the broad absorption band. In addition to these findings, we also discuss the correlation between the (+)C-H stretching vibrational modes in the 3000-3300 cm(-1) range of the infrared spectra and the intermolecular vibrational band in the low-wavenumber range. Finally, we describe some interesting characteristics of the intermolecular vibrational band observed in a wide range of imidazolium-based ionic liquids.

  12. Molecular dynamics simulation studies of the influence of imidazolium structure on the properties of imidazolium/azide ionic liquids.

    PubMed

    Hooper, Justin B; Starovoytov, Oleg N; Borodin, Oleg; Bedrov, Dmitry; Smith, Grant D

    2012-05-21

    Atomistic molecular dynamics simulations were performed on 1-butyl-3-methyl-imidazolium azide [bmim][N(3)], 1-butyl-2,3-dimethylimidazolium azide [bmmim][N(3)], and 1-butynyl-3-methyl-imidazolium azide [bumim][N(3)] ionic liquids. The many-body polarizable APPLE&P force field was augmented with parameters for the azide anion and the bumim cation. Good agreement between the experimentally determined and simulated crystal structure of [bumim][N(3)] as well as the liquid-state density and ionic conductivity of [bmmim][N(3)] were found. Methylation of bmim (yielding bmmim) resulted in dramatic changes in ion structuring in the liquid and slowing of ion motion. Conversely, replacing the butyl group of bmim with the smaller 2-butynyl group resulted in an increase of ion dynamics.

  13. Effects of imidazolium room temperature ionic liquids on the fluorescent properties of norfloxacin.

    PubMed

    Zou, Yujie; Wang, Huili; Wang, Wenwei; Ma, Meiping; Wang, Ping; Wang, Chengjun; Wang, Xuedong

    2012-01-01

    The effects of 12 imidazolium room temperature ionic liquids (RTILs), including [C(n)mim]BF4, [C(n)mim]PF6, and [C(n)mim]Br (n = 4, 6, 8, 10), on the fluorescent properties of norfloxacin were examined. The fluorescence intensity of norfloxacin at 0.1 mg/L in methanol significantly increased with the addition of [C(n)mim]BF4 and [C(n)mim]PF6 into the solvent at 0.1-15.0%. The sensitizing effect may result from the higher viscosity of the RTILs-methanol mixture solvent than that of the methanol itself. However, the quenching effect on fluorescence of norfloxacin was observed in [C(n)mim]Br-methanol solvent. The fluorescence intensities of norfloxacin decreased with an increase in the alkyl chain length of the alkyl substituents of the imidazolium ring of RTILs. The main interaction between the RTILs and norfloxacin is not by hydrogen bonding. The fact, that some RTILs can significantly sensitize fluorescence of norfloxacin, indicates that RTILs could be a group of promising solvents for development of sensitive spectrofluorimetric methods for determination of norfloxacin at ultra-trace levels in environmental samples. Copyright © 2011 John Wiley & Sons, Ltd.

  14. Guide to CO{sub 2} separations in imidazolium-based room-temperature ionic liquids

    SciTech Connect

    Bara, J.E.; Carlisle, T.K.; Gabriel, C.J.; Camper, D.; Finotello, A.; Gin, D.L.; Noble, R.D.

    2009-03-18

    Room-temperature ionic liquids (RTILs) are nonvolatile, tunable solvents. The solubilities of gases, particularly CO{sub 2}, N{sub 2}, and CH{sub 4}, have been studied in a number of RTILs. Process temperature and the chemical structures of the cation and anion have significant impacts on gas solubility and gas pair selectivity. Models based on regular solution theory and group contributions are useful to predict and explain CO{sub 2} solubility and selectivity in imidazolium-based RTILs. In addition to their role as a physical solvent, RTILs might also be used in supported ionic liquid membranes (SILMs) as a highly permeable and selective transport medium. Performance data for SILMs indicates that they exhibit large permeabilities as well as CO{sub 2}/N{sub 2} selectivities that outperform many polymer membranes. Furthermore, the greatest potential of RTILs for CO{sub 2} separations might lie in their ability to chemically capture CO{sub 2} when used in combination with amines. Amines can be tethered to the cation or the anion, or dissolved in RTILs, providing a wide range of chemical solvents for CO{sub 2} capture. However, despite all of their promising features, RTILs do have drawbacks to use in CO{sub 2} separations, which have been overlooked as appropriate comparisons of RTILs to common organic solvents and polymers have not been reported. A thorough summary of the capabilities-and limitations-of imidazolium-based RTILs in CO{sub 2}-based separations with respect to a variety of materials is thus provided.

  15. π(+)-π(+) stacking of imidazolium cations enhances molecular layering of room temperature ionic liquids at their interfaces.

    PubMed

    Tang, Fujie; Ohto, Tatsuhiko; Hasegawa, Taisuke; Bonn, Mischa; Nagata, Yuki

    2017-01-25

    The interfacial structure of room temperature ionic liquids (RTILs) controls many of the unique properties of RTILs, such as the high capacitance of RTILs and the efficiency of charge transport between RTILs and electrodes. RTILs have been experimentally shown to exhibit interfacial molecular layering structures over a 10 Å length scale. However, the driving force behind the formation of these layered structures has not been resolved. Here, we report ab initio molecular dynamics simulations of imidazolium RTIL/air and RTIL/graphene interfaces along with force field molecular dynamics simulations. We find that the π(+)-π(+) interaction of imidazolium cations enhances the layering structure of RTILs, despite the electrostatic repulsion. The length scales of the molecular layering at the RTIL/air and RTIL/graphene interfaces are very similar, manifesting the limited effect of the substrate on the interfacial organization of RTILs.

  16. Molecular simulation study of dynamical properties of room temperature ionic liquids with carbon pieces

    DOE PAGES

    Feng, Guang; Zhao, Wei; Cummings, Peter T.; ...

    2016-03-29

    Room temperature ionic liquids (RTILs) with dispersed carbon pieces exhibit distinctive physiochemical properties. In order to explore the molecular mechanism, RTILs/carbon pieces mixture we investigated it by molecular dynamics (MD) simulation in this work. Rigid and flexible carbon pieces in the form of graphene with different thicknesses and carbon nanotubes in different sizes were dispersed in a representative RTIL 1-butyl-3-methyl-imidazolium dicyanamide ([Bmim][DCA]). Our study demonstrated that the diffusion coefficients of RTILs in the presence of flexible carbons are similar to those of bulk RTILs at varying temperatures, which is in contrast to the decreased diffusion of RTILs in the presencemore » of rigid carbons. In addition, interfacial ion number density at rigid carbon surfaces was higher than that at flexible ones, which is correlated with the accessible external surface area of carbon pieces. The life time of cation-anion pair in the presence of carbon pieces also exhibited a dependence on carbon flexibility. RTILs with dispersed rigid carbon pieces showed longer ion pair life time than those with flexible ones, in consistence with the observation in diffusion coefficients. Furthermore, this work highlights the necessity of including the carbon flexibility when performing MD simulation of RTILs in the presence of dispersed carbon pieces in order to obtain the reliable dynamical and interfacial structural properties.« less

  17. Molecular simulation study of dynamical properties of room temperature ionic liquids with carbon pieces

    SciTech Connect

    Feng, Guang; Zhao, Wei; Cummings, Peter T.; Li, Song

    2016-03-29

    Room temperature ionic liquids (RTILs) with dispersed carbon pieces exhibit distinctive physiochemical properties. In order to explore the molecular mechanism, RTILs/carbon pieces mixture we investigated it by molecular dynamics (MD) simulation in this work. Rigid and flexible carbon pieces in the form of graphene with different thicknesses and carbon nanotubes in different sizes were dispersed in a representative RTIL 1-butyl-3-methyl-imidazolium dicyanamide ([Bmim][DCA]). Our study demonstrated that the diffusion coefficients of RTILs in the presence of flexible carbons are similar to those of bulk RTILs at varying temperatures, which is in contrast to the decreased diffusion of RTILs in the presence of rigid carbons. In addition, interfacial ion number density at rigid carbon surfaces was higher than that at flexible ones, which is correlated with the accessible external surface area of carbon pieces. The life time of cation-anion pair in the presence of carbon pieces also exhibited a dependence on carbon flexibility. RTILs with dispersed rigid carbon pieces showed longer ion pair life time than those with flexible ones, in consistence with the observation in diffusion coefficients. Furthermore, this work highlights the necessity of including the carbon flexibility when performing MD simulation of RTILs in the presence of dispersed carbon pieces in order to obtain the reliable dynamical and interfacial structural properties.

  18. Stability of the Liquid State of Imidazolium-Based Ionic Liquids under High Pressure at Room Temperature.

    PubMed

    Yoshimura, Yukihiro; Shigemi, Machiko; Takaku, Mayumi; Yamamura, Misaho; Takekiyo, Takahiro; Abe, Hiroshi; Hamaya, Nozomu; Wakabayashi, Daisuke; Nishida, Keisuke; Funamori, Nobumasa; Sato, Tomoko; Kikegawa, Takumi

    2015-06-25

    To understand the stability of the liquid phase of ionic liquids under high pressure, we investigated the phase behavior of a series of 1-alkyl-3-methylimidazolium tetrafluoroborate ([Cnmim][BF4]) homologues with different alkyl chain lengths for 2 ≤ n ≤ 8 up to ∼7 GPa at room temperature. The ionic liquids exhibited complicated phase behavior, which was likely due to the conformational flexibility in the alkyl chain. The present results reveal that [Cnmim][BF4] falls into superpressed state around 2-3 GPa range upon compression with an implication of multiple phase or structural transitions to ∼7 GPa. Remarkably, a characteristic nanostructural organization in ionic liquids largely diminishes at the superpressed state. The behaviors of imidazolium-based ionic liquids can be classified into, at least, three patterns: (1) pressure-induced crystallization, (2) superpressurization upon compression, and (3) decompression-induced crystallization from the superpressurized glass. Interestingly, the high-pressure phase behavior was relevant to the glass transition behavior at low temperatures and ambient pressure. As n increases, the glass transition pressure (pg) decreases (from 2.8 GPa to ∼2 GPa), and the glass transition temperature increases. The results indicate that the p-T range of the liquid phase is regulated by the alkyl chain length of [Cnmim][BF4] homologues.

  19. Spectroscopic insight into the interaction of bovine serum albumin with imidazolium-based ionic liquids in aqueous solution.

    PubMed

    Satish, Lakkoji; Millan, Sabera; Sahoo, Harekrushna

    2016-11-03

    The study of protein-ionic liquid interactions is very important because of the widespread use of ionic liquids as protein stabilizer in the recent years. In this work, the interaction of bovine serum albumin (BSA) with different imidazolium-based ionic liquids (ILs) such as [1-ethyl-3-methyl-imidazolium ethyl sulfate (EmimESO4 ), 1-ethyl-3-methyl-imidazolium chloride (EmimCl) and 1-butyl-3-methyl-imidazolium chloride (BmimCl)] has been investigated using different spectroscopic techniques. The intrinsic fluorescence of BSA is quenched by ILs by the dynamic mechanism. The thermodynamic analysis demonstrates that very weak interactions exist between BSA and ILs. 8-Anilino-1-naphthalenesulfonic acid (ANS) fluorescence and lifetime measurements reveal the formation of the compact structure of BSA in IL medium. The conformational changes of BSA were monitored by CD analysis. Temperature-dependent ultraviolet (UV) measurements were done to study the thermal stability of BSA. The thermal stability of BSA in the presence of ILs follows the trend EmimESO4  > EmimCl > BmimCl and in the presence of more hydrophobic IL, destabilization increases rapidly as a function of concentration.

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

    NASA Astrophysics Data System (ADS)

    Ennis, Elliot G.

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

  1. Molecularly imprinted SPE coupled with HPLC for the selective separation and enrichment of alkyl imidazolium ionic liquids in environmental water samples.

    PubMed

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

    2013-10-01

    A novel 1-butyl-3-methylimidazolium chloride ionic liquid surface imprinted solid-phase sorbent was synthesized. The as-prepared material was characterized by SEM, Brunauer-Emmett-Teller surface area analysis and Fourier Transform IR measurements. Then its adsorption properties for alkyl imidazolium ionic liquids, including adsorption capacities, adsorption kinetics, and properties of selective separation and enrichment were studied in detail. It was shown that the ionic liquid surface imprinted polymer exhibited high selective recognition characteristics for the imidazolium chloride ionic liquids with short alkyl chains (C(n)mimCl, n = 2, 4, 6, 8) and the adsorption equilibrium was achieved within 25 min. Various parameters were optimized for the 1-butyl-3-methylimidazolium chloride ionic liquid surface imprinted polymer SPE column, such as flow rate, eluent solvent, selectivity, and reusability of the column. Then, the SPE column coupled with HPLC was used for the determination of alkyl imidazolium ionic liquids. Experimental results showed that the existence of their structural analogs and common concomitants in environmental matrices did not affect the enrichment of 1-butyl-3-methyl imidazolium chloride ionic liquid. The average recoveries of 1-butyl-3-methylimidazolium chloride ionic liquid in spiked water samples were in the range of 92.0-102.0% with the RSD lower than 5.8%.

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

    PubMed

    Klee, Andreas; Prevost, Sylvain; Gradzielski, Michael

    2014-12-15

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

  3. Solvents Polarity Governs Ion Interactions and Transport in a Solvated Room Temperature Ionic Liquid

    SciTech Connect

    Osti, Naresh C; Van Aken, Katherine; Thompson, Matthew W; Tiet, Felix; Jiang, Dr. De-en; Cummings, Peter; Gogotsi, Yury G.; Mamontov, Eugene

    2017-01-01

    We explore the influence of the solvent dipole moment on cation anion interactions and transport in 1-butyl-3-methyl-imidazolium bis-(trifluoromethylsulfonyl), [BMIM+][Tf2N ]. Free energy profiles derived from atomistic molecular dynamics (MD) simulations show a correlation of the cation anion separation and the equilibrium depth of the potential of mean force with the dipole moment of the solvent. Correlations of the ion diffusivity with the dipole moment and the concentration of the solvent were further demonstrated by classical MD simulations. Quasi-elastic neutron scattering experiments with deuterated solvents reveal a complex picture of nanophase separation into the ionic liquid-rich and solvent-rich phases. The experiment corroborates the trend of concentration- and dipole moment-dependent enhancement of ion mobility by the solvent, as suggested by the simulations. Despite the considerable structural complexity of ionic liquid solvent mixtures, we can rationalize and generalize the trends governing ionic transport in these complex electrolytes.

  4. Biodegradation, ecotoxicity and UV254/H2O2 treatment of imidazole, 1-methyl-imidazole and N,N'-alkyl-imidazolium chlorides in water.

    PubMed

    Spasiano, D; Siciliano, A; Race, M; Marotta, R; Guida, M; Andreozzi, R; Pirozzi, F

    2016-12-01

    Imidazole-based compounds are used as reagents for the manufacturing of other compounds including imidazolium-based ionic liquids, which have been recently proposed as a green alternative to conventional solvents. Since some imidazole-based compounds have been demonstrated to be harmful to aquatic organisms, the removal of imidazole, 1-methylimidazole, 1-ethyl-3-methyl-imidazolium chloride and 1-butyl-3-methyl-imidazolium chloride from aqueous solutions was attempted by biological oxidation, direct UV254 photolysis, and UV254/H2O2 process at pH 5.5 and 8.5. Results showed that UV254/H2O2 treatment is an effective tool for the removal of the selected compounds at both pHs. In fact, the kinetic constants of the reaction between the photogenerated HO radicals and the four target compounds, estimated by means of both numerical and competition kinetic method, range between 2.32·10(9) M(-1) s(-1) and 5.52 ·10(9) M(-1) s(-1). Moreover, an ecotoxicity assessment of the contaminated water before and after initial treatment without further processing was assessed by using two living aquatic organisms: Raphidocelis subcapitata and Daphnia magna. The results of this assessment not only corresponded closely to previous findings (in terms of EC50 values) reported in the literature, but also indicated that, in some cases, UV254/H2O2 oxidation by-products could be even more toxic than parent compounds.

  5. Solvents Polarity Governs Ion Interactions and Transport in a Solvated Room Temperature Ionic Liquid

    DOE PAGES

    Osti, Naresh C; Van Aken, Katherine; Thompson, Matthew W; ...

    2017-01-01

    We explore the influence of the solvent dipole moment on cation anion interactions and transport in 1-butyl-3-methyl-imidazolium bis-(trifluoromethylsulfonyl), [BMIM+][Tf2N ]. Free energy profiles derived from atomistic molecular dynamics (MD) simulations show a correlation of the cation anion separation and the equilibrium depth of the potential of mean force with the dipole moment of the solvent. Correlations of the ion diffusivity with the dipole moment and the concentration of the solvent were further demonstrated by classical MD simulations. Quasi-elastic neutron scattering experiments with deuterated solvents reveal a complex picture of nanophase separation into the ionic liquid-rich and solvent-rich phases. The experimentmore » corroborates the trend of concentration- and dipole moment-dependent enhancement of ion mobility by the solvent, as suggested by the simulations. Despite the considerable structural complexity of ionic liquid solvent mixtures, we can rationalize and generalize the trends governing ionic transport in these complex electrolytes.« less

  6. Solvent Polarity Governs Ion Interactions and Transport in a Solvated Room-Temperature Ionic Liquid.

    PubMed

    Osti, Naresh C; Van Aken, Katherine L; Thompson, Matthew W; Tiet, Felix; Jiang, De-En; Cummings, Peter T; Gogotsi, Yury; Mamontov, Eugene

    2017-01-05

    We explore the influence of the solvent dipole moment on cation-anion interactions and transport in 1-butyl-3-methyl-imidazolium bis(trifluoromethylsulfonyl), [BMIM(+)][Tf2N(-)]. Free energy profiles derived from atomistic molecular dynamics (MD) simulations show a correlation of the cation-anion separation and the equilibrium depth of the potential of mean force with the dipole moment of the solvent. Correlations of the ion diffusivity with the dipole moment and the concentration of the solvent were further demonstrated by classical MD simulations. Quasi-elastic neutron scattering experiments with deuterated solvents reveal a complex picture of nanophase separation into the ionic liquid-rich and solvent-rich phases. The experiment corroborates the trend of concentration- and dipole moment-dependent enhancement of ion mobility by the solvent, as suggested by the simulations. Despite the considerable structural complexity of ionic liquid-solvent mixtures, we can rationalize and generalize the trends governing ionic transport in these complex electrolytes.

  7. Why does a reduction in hydrogen bonding lead to an increase in viscosity for the 1-butyl-2,3-dimethyl-imidazolium-based ionic liquids?

    PubMed

    Hunt, Patricia A

    2007-05-10

    1-Butyl-3-methyl-imidazolium chloride ([C(4)C(1)im]Cl) is a prototypical ionic liquid. Substitution for a methyl group at the 2-position of the cation to form 1-butyl-2,3-dimethyl-imidazolium ([C(4)C(1)mim]+) eliminates the main hydrogen-bonding interaction between the Cl anion and the imidazolium cation. Loss of this hydrogen-bonding interaction could be expected to lead to a reduction in melting point and a decrease in viscosity; however the opposite is observed experimentally; melting points and viscosity increase. The gas-phase structure and electronic properties of ion pairs formed from [C(4)C(1)mim]+ and Cl- are investigated to offer insight into this counter-intuitive behavior. We hypothesize that the effects due to a loss in hydrogen bonding are outweighed by those due to a loss in entropy. The amount of disorder in the system is reduced in two ways: elimination of ion-pair conformers, which are stable for [C(4)C(1)im]Cl but not [C(4)C(1)mim]Cl, and an increase in the rotational barrier of the butyl chain, which limits free rotation and facilitates alkyl chain association. The reduction in entropy leads to greater ordering within the liquid raising the melting point and increasing viscosity. The relative stabilities of 15 conformers with respect to anion position and alkyl chain rotation are reported at the B3LYP/6-31++G(d,p) level for [C(4)C(1)mim]Cl. Hydrogen bonding between the cation and the anion is examined on the basis of structural criteria and the computed vibrational spectra (IR and Raman). Spectra for the substituted and unsubstituted cations and ion pairs are compared, and modes are identified for [C(4)C(1)mim]Cl that could be used to differentiate between rotational conformers. A natural bond orbital analysis has also been carried out, and the resultant charge distribution is compared with that of the unsubstituted analogue [C(4)C(1)im]Cl.

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

    PubMed

    Mondal, Anirban; Balasubramanian, Sundaram

    2014-03-27

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

  9. Microscopic solvation environments in a prototype room-temperature ionic liquid as elucidated by resonance Raman spectroscopy of iodine and bromine

    NASA Astrophysics Data System (ADS)

    Saha, Satyen; Okajima, Hajime; Homma, Osamu; Hamaguchi, Hiro-o.

    2017-04-01

    Microscopic solvation environments in a prototype ionic liquid, bmimTf2N; 1-butyl-3-methyl-imidazolium-bis(trifluoromethanesulfonyl)imide, have been studied with the use of halides, X2 and Xn- (X = I, Br; n = 3,5), as molecular probes. Resonance Raman spectroscopy has been used to detect these halogen species existing in bmimTf2N as well as in reference solvents including heptane, cyclohexane, KX/H2O and benzene. In heptane and cyclohexane, only free X2 species are detected. In KX/H2O, only Xn- and, in benzene, only benzene-X2 complexes are detected. On the contrary, free X2 and Xn- are concomitantly detected in bmimTf2N, indicating that there are two distinct solvation environments in bmimTf2N, non-polar environments that solvate free X2 and polar environments that stabilize Xn-. These two distinct solvation environments are most likely to arise from microscopic structural heterogeneity of ionic liquids.

  10. Acetonitrile boosts conductivity of imidazolium ionic liquids.

    PubMed

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

    2012-07-05

    We apply a new methodology in the force field generation (Phys. Chem. Chem. Phys.2011, 13, 7910) to study binary mixtures of five imidazolium-based room-temperature ionic liquids (RTILs) with acetonitrile (ACN). Each RTIL is composed of tetrafluoroborate (BF(4)) anion and dialkylimidazolium (MMIM) cations. The first alkyl group of MIM is methyl, and the other group is ethyl (EMIM), butyl (BMIM), hexyl (HMIM), octyl (OMIM), and decyl (DMIM). Upon addition of ACN, the ionic conductivity of RTILs increases by more than 50 times. It significantly exceeds an impact of most known solvents. Unexpectedly, long-tailed imidazolium cations demonstrate the sharpest conductivity boost. This finding motivates us to revisit an application of RTIL/ACN binary systems as advanced electrolyte solutions. The conductivity correlates with a composition of ion aggregates simplifying its predictability. Addition of ACN exponentially increases diffusion and decreases viscosity of the RTIL/ACN mixtures. Large amounts of ACN stabilize ion pairs, although they ruin greater ion aggregates.

  11. Binary room-temperature ionic liquids based electrolytes solidified with SiO 2 nanoparticles for dye-sensitized solar cells

    NASA Astrophysics Data System (ADS)

    Lee, Kun-Mu; Chen, Po-Yen; Lee, Chuan-Pei; Ho, Kuo-Chuan

    In this study, binary ionic liquids (bi-IL) of imidazolium salts containing cations with different carbon side chain lengths (C = 2, 4, 6, 8) and anions such as iodide (I -), tetrafluoroborate (BF 4 -), hexafluorophosphate (PF 6 -) and trifluoromethansulfonate (SO 3CF 3 -) were used as electrolytes in dye-sensitized solar cells (DSSCs). On increasing the side chain length of imidazolinium salts, the diffusion coefficients of I 3 - and the cell conversion efficiencies decreased; however, the electron lifetimes in TiO 2 electrode increased. As for different anions, the cell which contains 1-butyl-3-methyl imidazolium trifluoromethansulfonate (BMISO 3CF 3) electrolyte has better performance than those containing BMIBF 4 and BMIPF 6. From the impedance measurement, the cell containing BMISO 3CF 3 electrolyte has a small charge transfer resistance (R ct2) at the TiO 2/dye/electrolyte interface. Moreover, the characteristic frequency peak for TiO 2 in the cell based on BMISO 3CF 3 is less than that of BMIBF 4 and BMIPF 6, indicating the cell with bi-IL electrolyte based on BMISO 3CF 3 has higher electron lifetime in TiO 2 electrode. Finally, the solid-state composite was introduced to form solid-state electrolytes for highly efficient DSSCs with a conversion efficiency of 4.83% under illumination of 100 mW cm -2. The long-term stability of DSSCs with a solidified bi-IL electrolyte containing SiO 2 nanoparticles, which is superior to that of a bi-IL electrolyte alone, was also presented.

  12. 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.

  13. Vibration Modes at Terahertz and Infrared Frequencies of Ionic Liquids Consisting of an Imidazolium Cation and a Halogen Anion

    PubMed Central

    Yamada, Toshiki; Tominari, Yukihiro; Tanaka, Shukichi; Mizuno, Maya; Fukunaga, Kaori

    2014-01-01

    The terahertz and infrared frequency vibration modes of room-temperature ionic liquids with imidazolium cations and halogen anions were extensively investigated. There is an intermolecular vibrational mode between the imidazolium ring of an imidazolium cation, a halogen atomic anion with a large absorption coefficient and a broad bandwidth in the low THz frequency region (13–130 cm−1), the intramolecular vibrational modes of the alkyl-chain part of an imidazolium cation with a relatively small absorption coefficient in the mid THz frequency region (130–500 cm−1), the intramolecular skeletal vibrational modes of an imidazolium ring affected by the interaction between the imidazolium ring, and a halogen anion with a relatively large absorption coefficient in a high THz frequency region (500–670 cm−1). Interesting spectroscopic features on the interaction between imidazolium cations and halogen anions was also obtained from spectroscopic studies at IR frequencies (550–3300 cm−1). As far as the frequency of the intermolecular vibrational mode is concerned, we found the significance of the reduced mass in determining the intermolecular vibration frequency. PMID:28788255

  14. Synthesis and Characterization of Imidazolium Linear Bisphenol Polycarbonate Hydroxides for Anion Exchange Membrane.

    PubMed

    Jang, Hohyoun; Hossain, Md Awlad; Lee, Soonho; Ha, Jaesung; Yoo, Jihoo; Kim, Kyungchul; Kim, Whangi

    2015-11-01

    A novel anion exchange membrane of imidazolium functionalized bisphenol polycarbonate was prepared for application in alkaline fuel cell. Di-imidazolium polycarbonate anionic membrane was synthesized by sequential interfacial polymerization, chloromethylation, substitution with 1-methylimidazole and ion exchange with 1.0 M KOH. Chloromethylation reaction was quantitative to achieve a high content of hydroxide ions. Introduction of conjugated imidazole ring in polymer plays an important role to improve both thermal and chemical stability. Bisphenol polycarbonate is a flexible polymer and shows a good solubility in polar organic solvent. The alkaline imidazolium bisphenol polycarbonate rendered an elevated molecular weight with excellent solubility in polar aprotic solvent. Different levels of substitution and ion exchange were investigated; the resulting membranes showed high ion exchange capacities (IECs) of up to 2.15 mmol g(-1). The imidazolium-functionalized copolymer membranes showed lower water affinity (14.2-42.8% at 30 degrees C) that satisfied an essential criterion for fuel cell application. The chemical structure of the imidazolium functionalized polycarbonate membrane was confirmed by 1H NMR spectroscopy, and also the membrane properties were evaluated by thermogravimetric analysis (TGA) and water uptake (WU), IEC and conductivity assessment. They exhibited hydroxide conductivity above 10(-2) S cm(-1) at room temperature and good chemical stability for up to five days without significant losses of ion conductivity.

  15. Imidazolium-Based Polymeric Materials as Alkaline Anion-Exchange Fuel Cell Membranes

    NASA Technical Reports Server (NTRS)

    Narayan, Sri R.; Yen, Shiao-Ping S.; Reddy, Prakash V.; Nair, Nanditha

    2012-01-01

    Polymer electrolyte membranes that conduct hydroxide ions have potential use in fuel cells. A variety of polystyrene-based quaternary ammonium hydroxides have been reported as anion exchange fuel cell membranes. However, the hydrolytic stability and conductivity of the commercially available membranes are not adequate to meet the requirements of fuel cell applications. When compared with commercially available membranes, polystyrene-imidazolium alkaline membrane electrolytes are more stable and more highly conducting. At the time of this reporting, this has been the first such usage for imidazolium-based polymeric materials for fuel cells. Imidazolium salts are known to be electrochemically stable over wide potential ranges. By controlling the relative ratio of imidazolium groups in polystyrene-imidazolium salts, their physiochemical properties could be modulated. Alkaline anion exchange membranes based on polystyrene-imidazolium hydroxide materials have been developed. The first step was to synthesize the poly(styrene-co-(1-((4-vinyl)methyl)-3- methylimidazolium) chloride through a free-radical polymerization. Casting of this material followed by in situ treatment of the membranes with sodium hydroxide solutions provided the corresponding hydroxide salts. Various ratios of the monomers 4-chloromoethylvinylbenzine (CMVB) and vinylbenzine (VB) provided various compositions of the polymer. The preferred material, due to the relative ease of casting the film, and its relatively low hygroscopic nature, was a 2:1 ratio of CMVB to VB. Testing confirmed that at room temperature, the new membranes outperformed commercially available membranes by a large margin. With fuel cells now in use at NASA and in transportation, and with defense potential, any improvement to fuel cell efficiency is a significant development.

  16. Ionothermal synthesis and crystal structure of a luminescent bipyridine bridged Zn(II) complex

    NASA Astrophysics Data System (ADS)

    Xiong, Wei; Xu, Wentao; Zhou, Youfu; Huang, Decai; Wang, Jinyun; Hong, Maochun; Xiong, Chunrong

    2014-02-01

    A luminescent complex, [Bmim]2[(ZnBr3)2(bpy)] (1) (bpy = 4,4‧-bipyridine, bmim = 1-butyl-3-methyl imidazolium), has been synthesized through ionothermal reaction and characterized systematically. Complex 1 exhibits isolated structure of bipyridine bridged zinc bromide units, stacked with 1-butyl-3-methyl imidazolium layers. The luminescent property of 1 has been investigated and supported by density functional theory (DFT) calculations, where the emissions are assigned to the halide-to-ligand charge transfer (XLCT) mixed with some metal-to-ligand charge transfer (MLCT) and intraligand-charge-transfer (ILCT).

  17. Imidazolium compounds are active against all stages of Trypanosoma cruzi.

    PubMed

    Faral-Tello, Paula; Liang, Mary; Mahler, Graciela; Wipf, Peter; Robello, Carlos

    2014-03-01

    Imidazolium salts are best known for their applications in organic synthesis as room-temperature ionic liquids, or as precursors of stable carbenes, but they also show important biological properties such as anti-oxidative effects, induction of mitochondrial membrane permeabilisation and inhibition of the infection cycle of Plasmodium falciparum. For these reasons, and since chemotherapy for Chagas disease is inefficient, the aim of this study was to test the use of imidazolium compounds against the kinetoplastid haemoflagellate aetiological agent for this disease, namely Trypanosoma cruzi. The results show that five of the tested compounds are more effective than the reference drug benznidazole against the epimastigote and trypomastigote forms of T. cruzi. Moreover, intracellular amastigotes were also affected by the compounds, which showed lower toxicity in host cells. Transmission electron microscopy analysis demonstrated that the tested agents induced alterations of the kinetoplast and particularly of the mitochondria, leading to extraordinary swelling of the organelle. These results further demonstrate that the test agents with the best profile are those bearing symmetrical bulky substituents at N(1) and N(3), displaying promising activity against all forms of T. cruzi, interesting selectivity indexes and exceptional activity at low doses. Accordingly, these agents represent promising candidates for the treatment of Chagas disease.

  18. Structural, thermal, dielectric and phonon properties of perovskite-like imidazolium magnesium formate.

    PubMed

    Mączka, Mirosław; Marinho Costa, Nathalia Leal; Gągor, Anna; Paraguassu, Waldeci; Sieradzki, Adam; Hanuza, Jerzy

    2016-05-18

    We report the synthesis and characterisation of a magnesium formate framework templated by protonated imidazole. Single-crystal X-ray diffraction data showed that this compound crystallizes in the monoclinic structure in the P21/n space group with lattice parameters a = 12.1246(4) Å, b = 12.2087(5) Å, c = 12.4991(4) Å and β = 91.39(1)°. The antiparallel arrangement of the dipole moments associated with imidazolium cations suggests the antiferroelectric character of the room-temperature phase. The studied compound undergoes a structural phase transition at 451 K associated with a halving of the c lattice parameter and the disappearance of the antiferroelectric order. The monoclinic symmetry is preserved and the new metrics are a = 12.261(7) Å, b = 12.290(4) Å, c = 6.280(4) Å, and β = 90.62(5)°. Raman and IR data are consistent with the X-ray diffraction data. They also indicate that the disorder of imidazolium cations plays a significant role in the mechanism of the phase transition. Dielectric data show that the phase transition is associated with a relaxor nature of electric ordering. We also report high-pressure Raman scattering studies of this compound that revealed the presence of two pressure-induced phase transitions near 3 and 7 GPa. The first transition is most likely associated with a rearrangement of the imidazolium cations without any significant distortion of these cations and the magnesium formate framework, whereas the second transition leads to strong distortion of both the framework and imidazolium cations. High-pressure data also show that imidazolium magnesium formate does not show any signs of amorphization up to 11.4 GPa.

  19. Imidazolium salt ion pairs in solution.

    PubMed

    Stassen, Hubert K; Ludwig, Ralf; Wulf, Alexander; Dupont, Jairton

    2015-06-01

    The formation, stabilisation and reactivity of contact ion pairs of non-protic imidazolium ionic liquids (ILs) in solution are conceptualized in light of selected experimental evidence as well theoretical calculations reported mainly in the last ten years. Electric conductivity, NMR, ESI-MS and IR data as well as theoretical calculations support not only the formation of contact ion pairs in solution, but also the presence of larger ionic and neutral aggregates even when dissolved in solvents with relatively high dielectric constants, such as acetonitrile and DMSO. The presence of larger imidazolium supramolecular aggregates is favoured at higher salt concentrations in solvents of low dielectric constant for ILs that contain shorter N-alkyl side chains associated with anions of low coordination ability. The stability and reactivity of neutral contact species are also dependent on the nature of the anion, imidazolium substituents, and are more abundant in ILs containing strong coordinating anions, in particular those that can form charge transfer complexes with the imidazolium cation. Finally, some ILs display reactivities as contact ion pairs rather than solvent-separated ions.

  20. In Situ Synthesis of Imidazolium-Crosslinked Ionogels via Debus-Radziszewski Reaction Based on PAMAM Dendrimers in Imidazolium Ionic liquid.

    PubMed

    Zhao, Xiaomeng; Guo, Shufei; Li, Hao; Liu, Jiahang; Liu, Xinxin; Song, Hongzan

    2017-09-12

    This study reports a remarkably facile method to synthesize novel ionogels with imidazolium cycle crosslinks based on polyamidoamine (PAMAM) dendrimers via one-pot, modified Debus-Radziszewski reaction in ionic liquid 1-ethyl-3-methylimidazolium acetate ([EMIM][OAc]). High room temperature ionic conductivity (up to 6.8 mS cm(-1) ) is achieved, and more remarkably, it can still exceed 1 mS cm(-1) when the dendrimer content reached 70% because PAMAM dendrimers are completely amorphous with many cavities and the newly formed imidazolium crosslinks contains ions. The elastic modulus of these ionogels can exceed 10(6) Pa due to the newly-formed rigid imidazolium crosslinks. Crucially, these ionogels are robust gels even at temperatures up to 160 °C. Such novel ionogels with high ionic conductivity, tunable modulus, and flexibility are desirable for use in high-temperature flexible electrochemical devices. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  1. 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.

  2. Improving the alkaline stability of imidazolium cations by substitution.

    PubMed

    Dong, Huilong; Gu, Fenglou; Li, Min; Lin, Bencai; Si, Zhihong; Hou, Tingjun; Yan, Feng; Lee, Shuit-Tong; Li, Youyong

    2014-10-06

    Imidazolium cations are promising candidates for preparing anion-exchange membranes because of their good alkaline stability. Substitution of imidazolium cations is an efficient way to improve their alkaline stability. By combining density functional theory calculations with experimental results, it is found that the LUMO energy correlates with the alkaline stability of imidazolium cations. The results indicate that alkyl groups are the most suitable substituents for the N3 position of imidazolium cations, and the LUMO energies of alkyl-substituted imidazolium cations depend on the electron-donating effect and the hyperconjugation effect. Comparing 1,2-dimethylimidazolium cations (1,2-DMIm+) and 1,3-dimethylimidazolium cations (1,3-DMIm+) with the same substituents reveals that the hyperconjugation effect is more significant in influencing the LUMO energy of 1,3-DMIms. This investigation reveals that LUMO energy is a helpful aid in predicting the alkaline stability of imidazolium cations.

  3. Angle-resolved X-ray photoelectron spectroscopy of the surface of imidazolium ionic liquids.

    PubMed

    Lockett, Vera; Sedev, Rossen; Bassell, Chris; Ralston, John

    2008-03-07

    The surfaces of three imidazolium based ionic liquids with a common anion were studied with angle-resolved X-ray photoelectron spectroscopy (XPS). The room temperature ionic liquids (RTILs): 1-butyl-3-methylimidazolium (bmim), 1-hexyl-3-methylimidazolium (hmim), and 1-octyl-3-methylimidazolium (omim) tetrafluoroborates, were meticulously purified and dried under vacuum. Survey and high-resolution spectra were obtained at different take-off angles (0-84 degrees ), thus increasing the surface sensitivity of the measurement. No impurities were detected and the survey spectra at normal emission (0 degrees ) confirmed the stoichiometric composition of the liquids. However, the spectra at take-off angles of 60, 70, 80 and 84 degrees indicated a higher amount of carbon. High resolution spectra of C1s, at these angles, showed an increased amount of aliphatic carbon when compared to the spectra at normal emission. The longer the side chain (R) of the imidazolium cation (Rmim), the larger was the amount of aliphatic carbon detected. Previous studies with other surface sensitive techniques have yielded contradictory conclusions about the surface orientation of the Rmim. We conclude unequivocally that the alkyl chain of the imidazolium ring of the investigated RTILs is oriented away from the liquid. Our study demonstrates the ability of XPS to probe the structure, along with the composition, of the free liquid surface by comparing signals from different penetration depths.

  4. C-H activation of imidazolium salts by Pt(0) at ambient temperature: synthesis of hydrido platinum bis(carbene) compounds.

    PubMed

    Duin, Marcel A; Clement, Nicolas D; Cavell, Kingsley J; Elsevier, Cornelis J

    2003-02-07

    A zerovalent platinum(carbene) complex with two monoalkene ligands, which is able to activate C-H bonds of imidazolium salts at room temperature to yield isolable hydrido platinum(II) bis(carbene) compounds, has been synthesised for the first time.

  5. Luminescent ionic liquid crystals from self-assembled BODIPY disulfonate and imidazolium frameworks.

    PubMed

    Olivier, Jean-Hubert; Camerel, Franck; Ulrich, Gilles; Barberá, Joaquín; Ziessel, Raymond

    2010-06-25

    A series of modular mesogenic salts based on the combination of anionic 4,4-difluoro-4-bora-3a,4a-diaza-s-indacene (F-BODIPY) 2,6-disulfonate dyes and trialkoxybenzyl-functionalised imidazolium cations has been designed and synthesised. Each salt contains a rigid dianionic BODIPY core associated with two imidazolium cations functionalised by 1,2,3-trialkoxybenzyl (alkyl=n-C(8), n-C(12) or n-C(16)) units or, in one case, with imidazolium cations functionalised by a trialkylgallate (3,4,5-trialkoxybenzoate) unit in which the 3,5-dialkyl groups are terminated with a polymerisable acrylate entity. All these compounds were highly fluorescent in solution with quantum yields ranging from 54 to 62%. In the solid state, the width of the emission band observed at around 650 nm is a clear signature of aggregation. With the trialkoxybenzylimidazolium cations, polarised optical microscopy (POM) and X-ray scattering experiments showed that columnar mesophases were formed. Differential scanning calorimetry (DSC) studies confirmed the mesomorphic behaviour from room temperature to about 130 degrees C for salts with alkyl chains containing 8, 12 and 16 carbon atoms. The strong luminescence of the BODIPY unit was maintained in the mesophase and fluorescence measurements confirmed the presence of J aggregates in all cases. The salt containing the gallate-functionalised imidazolium cations showed no mesomorphism but the acrylate terminal units could be used to engender photoinitiated polymerisation thereby allowing the material to be immobilised on glass plates. The polymerisation process was followed by FTIR spectroscopy and the fixed and patterned films were highly fluorescent with a solid-state emission close to that of the complex in the solid state.

  6. Surface structured platinum electrodes for the electrochemical reduction of carbon dioxide in imidazolium based ionic liquids.

    PubMed

    Hanc-Scherer, Florin A; Montiel, Miguel A; Montiel, Vicente; Herrero, Enrique; Sánchez-Sánchez, Carlos M

    2015-10-07

    The direct CO2 electrochemical reduction on model platinum single crystal electrodes Pt(hkl) is studied in [C2mim(+)][NTf2(-)], a suitable room temperature ionic liquid (RTIL) medium due to its moderate viscosity, high CO2 solubility and conductivity. Single crystal electrodes represent the most convenient type of surface structured electrodes for studying the impact of RTIL ion adsorption on relevant electrocatalytic reactions, such as surface sensitive electrochemical CO2 reduction. We propose here based on cyclic voltammetry and in situ electrolysis measurements, for the first time, the formation of a stable adduct [C2mimH-CO2(-)] by a radical-radical coupling after the simultaneous reduction of CO2 and [C2mim(+)]. It means between the CO2 radical anion and the radical formed from the reduction of the cation [C2mim(+)] before forming the corresponding electrogenerated carbene. This is confirmed by the voltammetric study of a model imidazolium-2-carboxylate compound formed following the carbene pathway. The formation of that stable adduct [C2mimH-CO2(-)] blocks CO2 reduction after a single electron transfer and inhibits CO2 and imidazolium dimerization reactions. However, the electrochemical reduction of CO2 under those conditions provokes the electrochemical cathodic degradation of the imidazolium based RTIL. This important limitation in CO2 recycling by direct electrochemical reduction is overcome by adding a strong acid, [H(+)][NTf2(-)], into solution. Then, protons become preferentially adsorbed on the electrode surface by displacing the imidazolium cations and inhibiting their electrochemical reduction. This fact allows the surface sensitive electro-synthesis of HCOOH from CO2 reduction in [C2mim(+)][NTf2(-)], with Pt(110) being the most active electrode studied.

  7. Strong tendency of homeotropic alignment and anisotropic lithium ion conductivity of sulfonate functionalized zwitterionic imidazolium ionic liquid crystals.

    PubMed

    Rondla, Rohini; Lin, Joseph C Y; Yang, C T; Lin, Ivan J B

    2013-09-17

    Here, we report the first attempt to investigate the liquid crystal (LC) behavior of SO3(-) functionalized imidazolium zwitterionic (SO3(-)ImZI) salts, which display homeotropic alignment on a glass slide without the aid of any aligning approach. Doping lithium salt to ImZI salts lowers the melting temperatures and raises the clearing temperatures substantially to form room temperature ImZILCs. Excellent anisotropic lithium ion conductivity is achieved; which is strengthened by their tendency for homeotropic alignment.

  8. Novel imidazolium salt--peptide conjugates and their antimicrobial activity.

    PubMed

    Reinhardt, A; Horn, M; Schmauck, J Pieper Gen; Bröhl, A; Giernoth, R; Oelkrug, C; Schubert, A; Neundorf, I

    2014-12-17

    Our study presents innovative research dealing with the synthesis and biological evaluation of conjugates out of antimicrobial peptides (AMPs) and imidazolium cations that are derived from ionic liquids. AMPs are considered as promising alternatives to common antibiotics due to their different activity mechanisms. Antibacterial effects have also been described for ionic liquids bearing imidazolium cations . Besides single coupling of carboxy-functionalized imidazolium cations to the peptide N-terminal we also developed conjugates bearing multiple copies of imidazolium cations. The combination of both compounds resulted in synergistic effects that were most pronounced when more imidazolium cations were attached to the peptides. In addition, antibacterial activity even in drug-resistant bacterial strains could be observed. Moreover, the novel compounds showed good selectivity only against bacterial cells, an observation that was further proven by lipid interaction studies using giant unilamellar vesicles.

  9. Modified normal-phase ion-pair chromatographic methods for the facile separation and purification of imidazolium-based ionic compounds

    SciTech Connect

    Urban, ND; Schenkel, MR; Robertson, LA; Noble, RD; Gin, DL

    2012-07-04

    lmidazolium- and oligo(imidazolium)-based ionic organic compounds are important in the design of room-temperature ionic liquid materials; however, the chromatographic analysis and separation of such compounds are often difficult. A convenient and inexpensive method for effective thin-layer chromatography (TLC) analysis and column chromatography separation of imidazolium-based ionic compounds is presented. Normal-phase ion-pair TLC is used to effectively analyze homologous mixtures of these ionic compounds. Subsequent separation of the mixtures is performed using ion-pair flash chromatography on normal-phase silica gel, yielding high levels of recovery. This method also results in a complete exchange of the counter anion on the imidazolium compounds to the anion of the ion-pair reagent. (C) 2012 Elsevier Ltd. All rights reserved.

  10. Direct Synthesis of Imidazolium-Functional Polyethylene by Insertion Copolymerization.

    PubMed

    Jian, Zhongbao; Leicht, Hannes; Mecking, Stefan

    2016-06-01

    Cationic imidazolium-functionalized polyethylene is accessible by insertion copolymerization of ethylene and allyl imidazolium tetrafluoroborate (AIm-BF4 ) with phosphinesulfonato palladium(II) catalyst precursors. Imidazolium-substituted repeat units are incorporated into the main chain and the initiating saturated chain end of the linear polymers, rather than the terminating unsaturated chain end. The counterion of the allyl imidazolium monomer is decisive, with the chloride analogue (AIm-Cl) no polymerization is observed. Stoichiometric studies reveal the formation of an inactive chloride complex from the catalyst precursor. An effect of moderate densities (0.5 mol%) of ionic groups on the copolymers' physical properties is exemplified by an enhanced wetting by water.

  11. Electrocatalytic CO2 Reduction by Imidazolium-Functionalized Molecular Catalysts.

    PubMed

    Sung, Siyoung; Kumar, Davinder; Gil-Sepulcre, Marcos; Nippe, Michael

    2017-09-26

    We present the first examples of CO2 electro-reduction catalysts that feature charged imidazolium groups in the secondary coordination sphere. The functionalized Lehn-type catalysts display significant differences in their redox properties and improved catalytic activities as compared to the conventional reference catalyst. Our results suggest that the incorporated imidazolium moieties do not solely function as a charged tag but also alter mechanistic aspects of catalysis.

  12. 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.

  13. Biodegradation of imidazolium ionic liquids by activated sludge microorganisms.

    PubMed

    Liwarska-Bizukojc, Ewa; Maton, Cedric; Stevens, Christian V

    2015-11-01

    Biological properties of ionic liquids (ILs) have been usually tested with the help of standard biodegradation or ecotoxicity tests. So far, several articles on the identification of intermediate metabolites of microbiological decay of ILs have been published. Simultaneously, the number of novel ILs with unrecognized characteristics regarding biodegradability and effect on organisms and environment is still increasing. In this work, seven imidazolium ionic liquids of different chemical structure were studied. Three of them are 1-alkyl-3-methyl-imidazolium bromides, while the other four are tetra- or completely substituted imidazolium iodides. This study focused on the identification of intermediate metabolites of the aforementioned ionic liquids subjected to biodegradation in a laboratory activated sludge system. Both fully substituted ionic liquids and 1-ethyl-3-methyl-imidazolium bromide were barely biodegradable. In the case of two of them, no biotransformation products were detected. The elongation of the alkyl side chain made the IL more susceptible for microbiological decomposition. 1-Decyl-3-methyl-imidazolium bromide was biotransformed most easily. Its primary biodegradation up to 100 % could be achieved. Nevertheless, the cleavage of the imidazolium ring has not been observed.

  14. X-ray diffraction, vibrational properties, and dielectric studies of 3-ammoniumpropyl imidazolium pentabromoantimonate (III)

    NASA Astrophysics Data System (ADS)

    Taher, Marwa Ben; Chaari, Najla; Bechir, Mohamed Ben; Chaabouni, Slaheddine

    2017-04-01

    A new organic-inorganic material 3-ammoniumpropyl imidazolium pentabromoantimonate (III) was reported. The title compound was synthesized at room temperature by slow evaporation and then characterized by single-crystal and powder X-ray diffraction, spectroscopic measurements, thermal analysis, and dielectric technique. It crystallizes in the non-centrosymmetric space group P212121 with the following unit cell parameters: a = 8.7120(7), b = 12.6608(1), c = 14.3498(1) Å with Z = 4. The crystal is built up of separated SbBr5 2- polyhedra anions and 3-ammoniumpropyl imidazolium cations. The cohesion of the structure is ensured by network of N-H…Br hydrogen bonds between the 3-ammoniumpropyl imidazolium cations and [SbBr5]2- anions, in which they may be effective in the stabilization of the crystal structure. The Raman and infrared spectra confirm the presence of both cationic [C6H13N3]2+ and anionic [SbBr5]2- entities. Dielectric data were analyzed using complex permittivity ɛ* and complex electrical modulus M* for the sample at various temperatures. The conductivity follows the Arrhenius low. The Z' and Zʺ versus frequency plots are well fitted to an equivalent circuit model. The circuits consist of the parallel combination of bulk resistance Rp and constant phase elements CPE. [C6H13N3]SbBr5 crystals undergo one endothermic peak at 333 K. This transition was detected by DSC and by dielectric measurements using the impedance and modulus spectroscopy techniques.

  15. Electrostatic and non-covalent interactions in dicationic imidazolium-sulfonium salts with mixed anions.

    PubMed

    Fei, Zhaofu; Zhu, Dun-Ru; Yan, Ning; Scopelliti, Rosario; Katsuba, Sergey A; Laurenczy, Gabor; Chisholm, Danielle M; McIndoe, J Scott; Seddon, Kenneth R; Dyson, Paul J

    2014-04-07

    A series of thioether-functionalised imidazolium salts have been prepared and characterized. Subsequent reaction of the thioether-functionalised imidazolium salts with iodomethane affords imidazolium-sulfonium salts composed of doubly charged cations and two different anions. Imidazolium-sulfonium salts containing a single anion type are obtained either by a solvent extraction method or by anion exchange. The imidazolium-sulfonium salts undergo a methyl-transfer reaction on exposure to water, giving rise to a new, singly charged imidazolium salt with iodide introduced at the 2-position of the imidazolium ring. Crystal structures of some of the imidazolium-sulfonium salts were determined by X-ray crystallography providing the topology of the interactions between the dications and the anions. Electrospray ionization mass spectrometry and quantum-chemical calculations were used to rationalise the relative strength of these interactions. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  16. Tribological characteristics of aluminum alloys against steel lubricated by ammonium and imidazolium ionic liquids

    SciTech Connect

    Qu, Jun; Blau, Peter Julian; Dai, Sheng; Luo, Huimin; Meyer III, Harry M; Truhan, John J.

    2009-01-01

    Sliding friction and wear characteristics of aluminum alloys against AISI 52100 steel lubricated by ionic liquids (ILs) were investigated at both room and elevated temperatures. The tested aluminum alloys include a commercially pure aluminum Al 1100, a wrought alloy Al 6061-T6511, and a cast alloy Al 319-T6. The lubricating performance of two ILs with the same anion, one ammonium-based [C8H17]3NH.Tf2N and one imidazolium-based C10mim.Tf2N, were compared each other and benchmarked against that of a conventional fully-formulated engine oil. Significant friction (up to 35%) and wear (up to 55%) reductions were achieved by the ammonium IL when lubricating the three aluminum alloys compared to the engine oil. The imidazolium IL performed better than the oil but not as well as the ammonium IL for Al 1100 and 319 alloys. However, accelerated wear was unexpectedly observed for Al 6061 alloy when lubricated by C10mim.Tf2N. Surface chemical analyses implied complex tribochemical reactions between the aluminum surfaces and ILs during the wear testing, which has been demonstrated either beneficial by forming a protective boundary film or detrimental by causing severe tribo-corrosion. The effects of the IL cation structure, aluminum alloy composition, and tribo-testing condition on the friction and wear results have been discussed.

  17. Synthesis and properties of alkoxy- and alkenyl-substituted peralkylated imidazolium ionic liquids.

    PubMed

    Maton, Cedric; Brooks, Neil R; Van Meervelt, Luc; Binnemans, Koen; Schaltin, Stijn; Fransaer, Jan; Stevens, Christian V

    2013-10-21

    Novel peralkylated imidazolium ionic liquids bearing alkoxy and/or alkenyl side chains have been synthesized and studied. Different synthetic routes towards the imidazoles and the ionic liquids comprising bromide, iodide, methanesulfonate, bis(trifluoromethylsulfonyl)imide ([NTf2](-)), and dicyanamide {[N(CN)2](-)} as the anion were evaluated, and this led to a library of analogues, for which the melting points, viscosities, and electrochemical windows were determined. Incorporation of alkenyl moieties hindered solidification, except for cations with high symmetry. The alkoxy-derivatized ionic liquids are often crystalline; however, room-temperature ionic liquids (RTILs) were obtained with the weakly coordinating anions [NTf2](-) and [N(CN)2](-). For the viscosities of the peralkylated RTILs, an opposite trend was found, that is, the alkoxy derivatives are less viscous than their alkenyl-substituted analogues. Of the crystalline compounds, X-ray diffraction data were recorded and related to their molecular properties. Upon alkoxy substitution, the electrochemical cathodic limit potential was found to be more positive, whereas the complete electrochemical window of the alkenyl-substituted imidazolium salts was shifted to somewhat more positive potentials.

  18. Rapid and accurate estimation of densities of room-temperature ionic liquids and salts.

    PubMed

    Ye, Chengfeng; Shreeve, Jean'ne M

    2007-03-01

    Volume parameters for room-temperature ionic liquids (RTILs) and salts were developed. For 59 of the most common imidazolium, pyridinium, pyrrolidinium, tetralkylammonium, and phosphonium-based RTILs, the mean absolute deviation (MAD) of the densities is 0.007 g cm-3; for 35 imidazolium-based room-temperature salts, the MAD is 0.020 g cm-3; and for 150 energetic salts, the MAD is 0.035 g cm-3. The experimental density (Y) for an alkylated imidazolium or pyridinium-based room-temperature ionic liquid is approximately proportional to its calculated density (X) in the solid state: Y = 0.948X - 0.110 (correlation coefficient: R2 = 0.998, for BF4-, PF6-, NTf2- -containing ionic liquids); Y = 0.934X - 0.070 (correlation coefficient: R2 = 0.999, for OTf-, CF3CO2-, N(CN)2- -containing ionic liquids).

  19. Interactions in 1-ethyl-3-methyl imidazolium tetracyanoborate ion pair: Spectroscopic and density functional study

    SciTech Connect

    Mao, James X.; Lee, Anita S.; Kitchin, John R.; Nulwala, Hunaid B.; Luebke, David R.; Damodaran, Krishnan

    2013-01-25

    Density Functional Theory is used to investigate a weakly coordinating room-temperature ionic liquid, 1-ethyl-3-methyl imidazolium tetracyanoborate ([Emim]{sup +}[TCB]{sup -}). Four locally stable conformers of the ion pair were located. Atoms-in-molecules (AIM) and electron density analysis indicated the existence of several hydrogen bonds. Further investigation through the Natural Bond Orbital (NBO) and Natural Energy Decomposition Analysis (NEDA) calculations provided insight into the origin of interactions in the [Emim]{sup +}[TCB]{sup -} ion pair. Strength of molecular interactions in the ionic liquid was correlated with frequency shifts of the characteristic vibrations of the ion pair. Harmonic vibrations of the ion pair were also compared with the experimental Raman and Infrared spectra. Vibrational frequencies were assigned by visualizing displacements of atoms around their equilibrium positions and through Potential Energy Distribution (PED) analysis.

  20. Interactions in 1-ethyl-3-methyl imidazolium tetracyanoborate ion pair: Spectroscopic and density functional study

    NASA Astrophysics Data System (ADS)

    Mao, James X.; Lee, Anita S.; Kitchin, John R.; Nulwala, Hunaid B.; Luebke, David R.; Damodaran, Krishnan

    2013-04-01

    Density Functional Theory is used to investigate a weakly coordinating room-temperature ionic liquid, 1-ethyl-3-methyl imidazolium tetracyanoborate ([Emim]+[TCB]-). Four locally stable conformers of the ion pair were located. Atoms-in-molecules (AIMs) and electron density analysis indicated the existence of several hydrogen bonds. Further investigation through the Natural Bond Orbital (NBO) and Natural Energy Decomposition Analysis (NEDA) calculations provided insight into the origin of interactions in the [Emim]+[TCB]- ion pair. Strength of molecular interactions in the ionic liquid was correlated with frequency shifts of the characteristic vibrations of the ion pair. Harmonic vibrations of the ion pair were also compared with the experimental Raman and Infrared spectra. Vibrational frequencies were assigned by visualizing displacements of atoms around their equilibrium positions and through Potential Energy Distribution (PED) analysis.

  1. Hydroxide Degradation Pathways for Imidazolium Cations. A DFT Study

    SciTech Connect

    Long, H.; Pivovar, B.

    2014-05-15

    Imidazolium cations are promising candidates as covalently tetherable cations for application in anion exchange membranes. They have generated specific interest in alkaline membrane fuel cell applications where ammonium-based cations have been the most commonly applied but have been found to be susceptible to hydroxide attack. In the search for high stability cations, a detailed understanding of the degradation pathways and reaction barriers is required. In this work, we investigate imidazolium and benzimidazolium cations in the presence of hydroxide using density functional theory calculations for their potential in alkaline membrane fuel cells. Moreover, the dominant degradation pathway for these cations is predicted to be the nucleophilic addition–elimination pathway at the C-2 atom position on the imidazolium ring. Steric interferences, introduced by substitutions at the C-2, C-4, and C-5 atom positions, were investigated and found to have a significant, positive impact on calculated degradation energy barriers. Benzimidazolium cations, with their larger conjugated systems, are predicted to degrade much faster than their imidazolium counterparts. Our results provide important insight into designing stable cations for anion exchange membranes. Some of the molecules studied have significantly increased degradation energy barriers suggesting that they could possess significantly improved (several orders of magnitude) durability compared to traditional cations and potentially enable new applications.

  2. Versatile cation transport in imidazolium based polymerized ionic liquids

    NASA Astrophysics Data System (ADS)

    Evans, Christopher; Segalman, Rachel

    Polymerized ionic liquids (PIL) with tethered imidazolium groups are able to conduct a diverse array of cations relevant for energy applications. The well-known complexation of imidazolium with transition metals is exploited to bind ions such as H +, Li+, Cu2+, and Ni2+ by doping the neutral PIL with the appropriate Cation-TFSI- salt. Conductivities were first determined via AC impedance indicating that H+ salts lead to the highest conductivity (due to low ion mass and potential Grotthus mechanism) followed by Cu2+, Li+, Ag+, and Ni2+. The equilibrium constant for imidazolium complexation is larger for Cu2+ relative to Li-, Ag-, and Ni-imidazolium complexes leading to greater salt dissociation and higher conductivities. For LiTFSI and CuTFSI2 salts, metallic lithium or copper electrodes were employed in battery cells to pass a steady DC current and confirm that the cations are in fact carrying current. Interestingly, the divalent Cu2+ also ionically crosslinks the polymer leading to a plateau in the viscosity. Thus, divalent ions provide an unique route to high conductivity, high modulus polymeric electrolytes. Future studies involving ZnTFSI2 and MgTFSI2 for battery applications are proposed to examine how versatile the PIL platform is for cation transport.

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

    PubMed

    Kumar, Vinod; Pandey, Siddharth

    2012-10-04

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

  4. T-shaped ionic liquid crystals based on the imidazolium motif: exploring substitution of the C-2 imidazolium carbon atom.

    PubMed

    Goossens, Karel; Wellens, Sil; Van Hecke, Kristof; Van Meervelt, Luc; Cardinaels, Thomas; Binnemans, Koen

    2011-04-04

    In this contribution the first examples of so-called rigid-core, T-shaped imidazolium ionic liquid crystals, in which the C-2 atom of the imidazolium ring is substituted with an aryl moiety decorated with one or two alkoxy chains, are described. The length of the alkoxy chain(s) was varied from six to eighteen carbon atoms (n=6, 10, 14-18). Whereas the compounds with one long alkoxy chain display only smectic A phases, the salts containing two alkoxy chains exhibit smectic A, multicontinuous cubic, as well as hexagonal columnar phases, as evidenced by polarising optical microscopy, differential scanning calorimetry, and powder X-ray diffraction. Structural models are proposed for the self-assembly of the molecules within the mesophases. The imidazolium head groups and the iodide counterions were found to adopt a peculiar orientation in the central part of the columns of the hexagonal columnar phases. The enantiotropic cubic phase shown by the 1,3-dimethyl-2-[3,4-bis(pentadecyloxy)phenyl]imidazolium iodide salt has a multicontinuous Pm ̄3m structure. To the best of our knowledge, this is the first example of a thermotropic cubic mesophase of this symmetry.

  5. Direct exfoliation of natural graphite into micrometer size few layers graphene sheets using ionic liquids

    SciTech Connect

    Wang, Xiqing; Fulvio, Pasquale F; Baker, Gary A; Veith, Gabriel M; Unocic, Raymond R; Mahurin, Shannon Mark; Dai, Sheng

    2010-01-01

    Stable high-concentration suspensions (up to 0.95 mg mL{sup -1}) of non-oxidized few layer graphene (FLG), five or less sheets, with micrometre-long edges were obtained via direct exfoliation of natural graphite flakes in ionic liquids, such as 1-butyl-3-methyl-imidazolium bis(trifluoro-methane-sulfonyl)imide ([Bmim]-[Tf{sub 2}N]), by tip ultrasonication.

  6. Ionic liquids as a novel solvent for lanthanide extraction.

    PubMed

    Nakashima, Kazunori; Kubota, Fukiko; Maruyama, Tatsuo; Goto, Masahiro

    2003-08-01

    Octyl(phenyl)-N,N-diisobutylcarbamoylmethyl phosphine oxide (CMPO) dissolved in an ionic liquids, 1-butyl-3-methyl-imidazolium hexafluorophosphate, greatly enhances extractability and selectivity of lanthanide cations compared to that dissolved in conventional organic solvents; further, the recovery of lanthanides extracted into ionic liquids can be accomplished using several stripping solutions containing complexing agents. The possibility of utilizing ionic liquids as novel separation media in an industrial liquid-liquid extraction process was demonstrated.

  7. Direct exfoliation of natural graphite into micrometer size few layers graphene sheets using ionic liquids

    SciTech Connect

    Wang, X.; Fulvio, P. F.; Baker, G. A.; Veith, G. M.; Unocic, R. R.; Mahurin, S., M.; Chi, M.; Dai, S.

    2010-01-01

    Stable high-concentration suspensions (up to 0.95 mg mL-1) of non-oxidized few layer graphene (FLG), five or less sheets, with micrometre-long edges were obtained via direct exfoliation of natural graphite flakes in ionic liquids, such as 1-butyl-3-methyl-imidazolium bis(trifluoro-methane-sulfonyl)imide ([Bmim]-[Tf2N]), by tip ultrasonication.

  8. Chemical Kinetics Interpretation of Hypergolicity of Dicyanamide Ionic Liquid-based Systems (PREPRINT)

    DTIC Science & Technology

    2011-03-04

    REPORT DOCUMENTATION PAGE Form Approved OMB No. 0704-0188 Public reporting burden for this collection of information is estimated to average 1 ...currently valid OMB control number. PLEASE DO NOT RETURN YOUR FORM TO THE ABOVE ADDRESS. 1 . REPORT DATE (DD-MM-YYYY) 04-03-2011 2. REPORT TYPE Journal...observed during hypergolic ignition of the ionic liquid; 1 -butyl-3-methyl-imidazolium dicyanamide with WFNA. Sensitivity analyses have been

  9. Solute-solvent interactions in imidazolium camphorsulfonate ionic liquids.

    PubMed

    Nobuoka, Kaoru; Kitaoka, Satoshi; Iio, Masashi; Harran, Thomas; Ishikawa, Yuichi

    2007-11-28

    We directly observe the interaction between 1-butyl-3-methylimidazolium (bmim) or 1-butyl-2,3-dimethylimidazolium (bm(2)im) and the solute, ethyl acrylate (EA), which is the popular dienophile in the Diels-Alder reaction and an H-bonding acceptor, by using specially designed electrospray mass spectrometry. In imidazolium ionic liquids, cation-anion interactions are controlled by selecting the appropriate anion, and the naked C(2)-H of imidazolium, which loosely interacts with its counterion, can readily interact with an H-bonding acceptable solute. The ion-counterion (solvent-solvent) interaction affects the ion-solute (solvent-solute) interaction. This relation is one of the key criteria for selecting the cation-anion combination in tailoring ILs.

  10. 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.

  11. Imidazolium-based titanium substrates against bacterial colonization.

    PubMed

    Cavoue, T; Bounou Abassi, H; Vayssade, M; Nguyen Van Nhien, A; Kang, I-K; Kwon, G-W; Pourceau, G; Dubot, P; Abbad Andaloussi, S; Versace, D-L

    2017-02-28

    Nosocomial infections are often induced by the presence of pathogenic organisms on the surface of medical devices or hospital equipment. Chemical modifications of the surface are recognized as efficient strategies to prevent bacterial adhesion but they may have a negative impact on the material's interaction with living tissues. Here we have developed a photoactivated method for the modification of titanium substrates. A photoinduced technique employing a grafting-onto process has been successfully performed to covalently anchor an imidazolium-derivative siloxane onto titanium surfaces. Imidazolium surfaces showed higher bacteria-repellency performances than native titanium substrates, achieving more than 98% anti-adhesion efficiency against Escherichia coli after 24 h of incubation. In addition, these surfaces allowed for the adhesion and viability of osteoblasts cells without evidence of cytotoxicity.

  12. Small nickel nanoparticle arrays from long chain imidazolium ionic liquids

    DOE PAGES

    Yang, Mei; Campbell, Paul S.; Santini, Catherine C.; ...

    2013-11-08

    A series of six long chain alkyl mono- and bi-cationic imidazolium based salts with bis(trifluoromethylsulfonyl)imide (NTf2–) as the anion were synthesized and characterized. Single crystal structure of 1-methyl-3-octadecylimidazolium bis(trifluoromethylsulfonyl)imide could be obtained by X-ray analysis. All these long chain alkyl imidazolium based ILs were applied in the synthesis of nickel nanoparticles via chemical decomposition of an organometallic precursor of nickel. In these media, spontaneous decomposition of Ni(COD)2 (COD = 1,5-cyclooctadiene) in the absence of H2 occurred giving small NPs (≤4 nm) with narrow size distributions. Interestingly, formation of regularly interspaced NP arrays was also observed in long chain ILs. Lastly,more » such array formation could be interesting for potential applications such as carbon nanotube growth.« less

  13. Small nickel nanoparticle arrays from long chain imidazolium ionic liquids

    SciTech Connect

    Yang, Mei; Campbell, Paul S.; Santini, Catherine C.; Mudring, Anja -Verena

    2013-11-08

    A series of six long chain alkyl mono- and bi-cationic imidazolium based salts with bis(trifluoromethylsulfonyl)imide (NTf2–) as the anion were synthesized and characterized. Single crystal structure of 1-methyl-3-octadecylimidazolium bis(trifluoromethylsulfonyl)imide could be obtained by X-ray analysis. All these long chain alkyl imidazolium based ILs were applied in the synthesis of nickel nanoparticles via chemical decomposition of an organometallic precursor of nickel. In these media, spontaneous decomposition of Ni(COD)2 (COD = 1,5-cyclooctadiene) in the absence of H2 occurred giving small NPs (≤4 nm) with narrow size distributions. Interestingly, formation of regularly interspaced NP arrays was also observed in long chain ILs. Lastly, such array formation could be interesting for potential applications such as carbon nanotube growth.

  14. Irreversible thermochromism in copper chloride Imidazolium Nanoparticle Networks.

    PubMed

    Kronstein, Martin; Kriechbaum, Konstantin; Akbarzadeh, Johanna; Peterlik, Herwig; Neouze, Marie-Alexandra

    2013-08-14

    In this work Imidazolium Nanoparticle Networks (INNs) with chloride counter-ions were used to complex copper dichloride. This complexation reaction leads to the formation of a green material. The properties of the copper INN material were compared to: first, copper imidazolium complexes, without the presence of silica nanoparticles, which are not thermochromic; second, chloride-containing INN material. The copper INN material showed irreversible thermochromic behaviour, with a clear colour change from green to yellow at 180 °C, which is due to a configuration change of the copper complex from planar to tetragonal. This structural change was studied using DSC and in situ SAXS measurements during heat treatment. The thermochromic material is stable under air up to 250 °C. This preliminary study opens the door of optical sensors for INN materials.

  15. Catalytically active lead(ii)-imidazolium coordination assemblies with diversified lead(ii) coordination geometries.

    PubMed

    Naga Babu, Chatla; Suresh, Paladugu; Srinivas, Katam; Sathyanarayana, Arruri; Sampath, Natarajan; Prabusankar, Ganesan

    2016-05-10

    Five Pb(ii)-imidazolium carboxylate coordination assemblies with novel structural motifs were derived from the reaction between the corresponding flexible, semi flexible or rigid imidazolium carboxylic acid ligands and lead nitrate. The imidazolium linker present in these molecules likely plays a triple role such as the counter ion to balance the metal charge, the ligand being an integral part of the final product and the catalyst facilitating carbon-carbon bond formation reaction. These lead-imidazolium coordination assemblies exhibit, variable chemical and thermal stabilities, as well as catalytic activity. These newly prepared catalysts are highly active towards benzoin condensation reactions with good functional group tolerance.

  16. Partition coefficients of organic compounds between water and imidazolium-, pyridinium-, and phosphonium-based ionic liquids.

    PubMed

    Padró, Juan M; Pellegrino Vidal, Rocío B; Reta, Mario

    2014-12-01

    The partition coefficients, P IL/w, of several compounds, some of them of biological and pharmacological interest, between water and room-temperature ionic liquids based on the imidazolium, pyridinium, and phosphonium cations, namely 1-octyl-3-methylimidazolium hexafluorophosphate, N-octylpyridinium tetrafluorophosphate, trihexyl(tetradecyl)phosphonium chloride, trihexyl(tetradecyl)phosphonium bromide, trihexyl(tetradecyl)phosphonium bis(trifluoromethylsulfonyl)imide, and trihexyl(tetradecyl)phosphonium dicyanamide, were accurately measured. In this way, we extended our database of partition coefficients in room-temperature ionic liquids previously reported. We employed the solvation parameter model with different probe molecules (the training set) to elucidate the chemical interactions involved in the partition process and discussed the most relevant differences among the three types of ionic liquids. The multiparametric equations obtained with the aforementioned model were used to predict the partition coefficients for compounds (the test set) not present in the training set, most being of biological and pharmacological interest. An excellent agreement between calculated and experimental log P IL/w values was obtained. Thus, the obtained equations can be used to predict, a priori, the extraction efficiency for any compound using these ionic liquids as extraction solvents in liquid-liquid extractions.

  17. Effect of molecular orientation angle of imidazolium ring on frictional properties of imidazolium-based ionic liquid.

    PubMed

    Watanabe, S; Nakano, M; Miyake, K; Tsuboi, R; Sasaki, S

    2014-07-15

    Ionic liquids have significant potential as lubricants, and it is known that ionic liquids exhibit characteristic behavior at solid-liquid interfaces. Although it is believed that the structure of ionic liquids at the interface contributes to the tribological properties in the region of boundary-mixed lubrication, this contribution has not been clarified because such analysis is difficult. In this research, we clarify the lubrication mechanism of an imidazolium-based ionic liquid by comparing the results of friction tests with interfacial molecular orientation analysis using sum frequency generation spectroscopy. Consequently, we clarify that the tilt angle of the imidazolium ring affects the friction coefficient of the ionic liquid; that is, the larger tilt angle, the lower the friction coefficient.

  18. Effect of imidazolium-based ionic liquids on bacterial growth inhibition investigated via experimental and QSAR modelling studies.

    PubMed

    Ghanem, Ouahid Ben; Mutalib, M I Abdul; El-Harbawi, Mohanad; Gonfa, Girma; Kait, Chong Fai; Alitheen, Noorjahan Banu Mohamed; Leveque, Jean-Marc

    2015-10-30

    Tuning the characteristics of solvents to fit industrial requirements has currently become a major interest in both academic and industrial communities, notably in the field of room temperature ionic liquids (RTILs), which are considered one of the most promising green alternatives to molecular organic solvents. In this work, several sets of imidazolium-based ionic liquids were synthesized, and their toxicities were assessed towards four human pathogens bacteria to investigate how tunability can affect this characteristic. Additionally, the toxicity of particular RTILs bearing an amino acid anion was introduced in this work. EC50 values (50% effective concentration) were established, and significant variations were observed; although all studied ILs displayed an imidazolium moiety, the toxicity values were found to vary between 0.05 mM for the most toxic to 85.57 mM for the least toxic. Linear quantitative structure activity relationship models were then developed using the charge density distribution (σ-profiles) as molecular descriptors, which can yield accuracies as high as 95%. Copyright © 2015 Elsevier B.V. All rights reserved.

  19. Microemulsions with an ionic liquid surfactant and room temperature ionic liquids as polar pseudo-phase.

    PubMed

    Zech, Oliver; Thomaier, Stefan; Bauduin, Pierre; Rück, Thomas; Touraud, Didier; Kunz, Werner

    2009-01-15

    In this investigation we present for the first time microemulsions comprising an ionic liquid as surfactant and a room-temperature ionic liquid as polar pseudo-phase. Microemulsions containing the long- chain ionic liquid1-hexadecyl-3-methyl-imidazolium chloride ([C16mim][Cl]) as surfactant, decanol as cosurfactant, dodecaneas continuous phase and room temperature ionic liquids (ethylammonium nitrate (EAN) and 1-butyl-3-methylimidazolium tetrafluoroborate ([bmim

  20. Hydrogen fluoride capture by imidazolium acetate ionic liquid

    NASA Astrophysics Data System (ADS)

    Chaban, Vitaly

    2015-04-01

    Extraction of hydrofluoric acid (HF) from oils is a drastically important problem in petroleum industry, since HF causes quick corrosion of pipe lines and brings severe health problems to humanity. Some ionic liquids (ILs) constitute promising scavenger agents thanks to strong binding to polar compounds and tunability. PM7-MD simulations and hybrid density functional theory are employed here to consider HF capture ability of ILs. Discussing the effects and impacts of the cation and the anion separately and together, we evaluate performance of imidazolium acetate and outline systematic search guidelines for efficient adsorption and extraction of HF.

  1. Novel luminescent hybrids by incorporating rare earth β-diketonates into polymers through ion pairing with an imidazolium counter ion.

    PubMed

    Li, Qiu-Ping; Yan, Bing

    2013-09-01

    A series of luminescent polymers are synthesized by incorporating rare earth complex units into polymer matrices. Firstly, we functionalize the selected polymer matrices with the imidazolium moieties, and then introduce the rare earth tetrakis(β-diketonate) complexes into polymer matrices through a mild anion exchange method. The resulting materials are characterized by FTIR, XRD, EDAX, SEM, thermogravimetric analysis, luminescence excitation spectra and emission spectra, luminescence lifetime measurements and diffuse reflectance UV-Vis spectra. The photoluminescence measurements indicate that all these rare earth complex functionalized polymers exhibit a characteristic luminescence emission originating from the corresponding rare earth ions. Among the hybrids, the europium tetrakis(TTA) complex functionalized polymers show remarkable luminescence quantum yields and relatively long (5)D0 lifetimes at room temperature.

  2. Conformational Properties of a Polymer in an Ionic Liquid: Computer Simulations and Integral Equation Theory of a Coarse-Grained Model.

    PubMed

    Choi, Eunsong; Yethiraj, Arun

    2015-07-23

    We study the conformational properties of polymers in room temperature ionic liquids using theory and simulations of a coarse-grained model. Atomistic simulations have shown that single poly(ethylene oxide) (PEO) molecules in the ionic liquid 1-butyl 3-methyl imidazolium tetrafluoroborate ([BMIM][BF4]) are expanded at room temperature (i.e., the radius of gyration, Rg), scales with molecular weight, Mw, as Rg ∼ Mw(0.9), instead of the expected self-avoiding walk behavior. The simulations were restricted to fairly short chains, however, which might not be in the true scaling regime. In this work, we investigate a coarse-grained model for the behavior of PEO in [BMIM][BF4]. We use existing force fields for PEO and [BMIM][BF4] and Lorentz–Berthelot mixing rules for the cross interactions. The coarse-grained model predicts that PEO collapses in the ionic liquid. We also present an integral equation theory for the structure of the ionic liquid and the conformation properties of the polymer. The theory is in excellent agreement with the simulation results. We conclude that the properties of polymers in ionic liquids are unusually sensitive to the details of the intermolecular interactions. The integral equation theory is sufficiently accurate to be a useful guide to computational work.

  3. Physicochemical Properties of Imidazolium-derived Ionic Liquids with Different C-2 Substitutions

    SciTech Connect

    Liao, Chen; Shao, Nan; Han, Kee Sung; Sun, Xiao-Guang; Jiang, Deen; Hagaman, Edward {Ed} W; Dai, Sheng

    2011-01-01

    Five room temperature ionic liquids based on C-2 substituted imidazolium cations and bis(trifluoromethanesulfonyl)imide (TFSI) anion were synthesized and their physicochemical properties: thermal property, density, viscosity, ionic conductivity, self-diffusion coefficients, and electrochemical stability were systematically investigated. The temperature dependence of both viscosity and ionic conductivities of these ionic liquids can be described by Vogel-Fulcher-Tamman (VFT) equation. Compared with the reference, 1-propyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide, the introduction of functional groups at the C-2 position generally increased the viscosity and lowered the ionic conductivity. The introduction of ether group ( CH2OCH2CH2CH2CH3) at the C-2 position not only enhanced the reduction stability of the ionic liquids but also exhibited the lowest solid electrolyte interfacial resistance (RSEI). On the contrary, the introduction of a cyano group ( CN) at the C-2 position not only decreased the reduction stability but also adversely increased the SEI resistance. The effect of the C-2 substitution on the reduction stability was explained by the change of the energy level of the lowest unoccupied molecular orbital. The self-diffusion coefficients (D) of each ion were measured by pulsed field gradient nuclear magnetic resonance (PFG-NMR). The lithium transference number (tLi) of 0.5 M LiTFSI/IL solutions calculated from the self-diffusion coefficients was in the range of 0.04 and 0.09.

  4. Highly Luminescent Salts Containing Well-Shielded Lanthanide-Centered Complex Anions and Bulky Imidazolium Countercations

    SciTech Connect

    Tang, Si-Fu; Lorbeer, Chantal; Wang, Xinjiao; Ghosh, Pushpal; Mudring, Anja-Verena

    2014-09-02

    Four salts containing imidazolium cations and europium(III)- or terbium(III)-centered complex anions have been successfully synthesized from an ethanol/H2O solution. The single-crystal X-ray diffraction analyses reveal that these compounds have a common formula of [R][Ln(DETCAP)4] [R = 1-ethyl-3-methylimidazolium (C2mim), Ln = Eu (1) and Tb (2); R = 1-butyl-3-methylimidazolium (C4mim), Ln = Eu (3) and Tb (4); DETCAP = diethyl-2,2,2-trichloroacetylphosphoramidate], in which the lanthanide centers are chelated by four chelating pseudo-β-diketonate ligands (DETCAP)-, forming the respective complex anions. Their thermal behaviors and stabilities were also investigated to study the role of the length of the side chain in the cations. Fluorescence measurements at both room temperature and liquid-nitrogen temperature show that these materials show intense characteristic europium(III) or terbium(III) emissions and have long decay times. Their overall quantum yields were determined to be in the range of 30–49%.

  5. Quasielastic neutron scattering studies on glass-forming ionic liquids with imidazolium cations

    SciTech Connect

    Kofu, Maiko; Inamura, Yasuhiro; Miyazaki, Kyoko; Yamamuro, Osamu; Tyagi, Madhusudan

    2015-12-21

    Relaxation processes for imidazolium-based ionic liquids (ILs) were investigated by means of an incoherent quasielastic neutron scattering technique. In order to clarify the cation and anion effects on the relaxation processes, ten samples were measured. For all of the samples, we found three relaxations at around 1 ps, 10 ps, and 100 ps-10 ns, each corresponding to the alkyl reorientation, the relaxation related to the imidazolium ring, and the ionic diffusion. The activation energy (E{sub a}) for the alkyl relaxation is insensitive to both anion and alkyl chain lengths. On the other hand, for the imidazolium relaxation and the ionic diffusion processes, E{sub a} increases as the anion size decreases but is almost independent of the alkyl chain length. This indicates that the ionic diffusion and imidazolium relaxation are governed by the Coulombic interaction between the core parts of the cations (imidazolium ring) and the anions. This is consistent with the fact that the imidazolium-based ILs have nanometer scale structures consisting of ionic and neutral (alkyl chain) domains. It is also found that there is a clear correlation between the ionic diffusion and viscosity, indicating that the ionic diffusion is mainly associated with the glass transition which is one of the characteristics of imidazolium-based ILs.

  6. Quasielastic neutron scattering studies on glass-forming ionic liquids with imidazolium cations.

    PubMed

    Kofu, Maiko; Tyagi, Madhusudan; Inamura, Yasuhiro; Miyazaki, Kyoko; Yamamuro, Osamu

    2015-12-21

    Relaxation processes for imidazolium-based ionic liquids (ILs) were investigated by means of an incoherent quasielastic neutron scattering technique. In order to clarify the cation and anion effects on the relaxation processes, ten samples were measured. For all of the samples, we found three relaxations at around 1 ps, 10 ps, and 100 ps-10 ns, each corresponding to the alkyl reorientation, the relaxation related to the imidazolium ring, and the ionic diffusion. The activation energy (Ea) for the alkyl relaxation is insensitive to both anion and alkyl chain lengths. On the other hand, for the imidazolium relaxation and the ionic diffusion processes, Ea increases as the anion size decreases but is almost independent of the alkyl chain length. This indicates that the ionic diffusion and imidazolium relaxation are governed by the Coulombic interaction between the core parts of the cations (imidazolium ring) and the anions. This is consistent with the fact that the imidazolium-based ILs have nanometer scale structures consisting of ionic and neutral (alkyl chain) domains. It is also found that there is a clear correlation between the ionic diffusion and viscosity, indicating that the ionic diffusion is mainly associated with the glass transition which is one of the characteristics of imidazolium-based ILs.

  7. Quasielastic neutron scattering studies on glass-forming ionic liquids with imidazolium cations

    NASA Astrophysics Data System (ADS)

    Kofu, Maiko; Tyagi, Madhusudan; Inamura, Yasuhiro; Miyazaki, Kyoko; Yamamuro, Osamu

    2015-12-01

    Relaxation processes for imidazolium-based ionic liquids (ILs) were investigated by means of an incoherent quasielastic neutron scattering technique. In order to clarify the cation and anion effects on the relaxation processes, ten samples were measured. For all of the samples, we found three relaxations at around 1 ps, 10 ps, and 100 ps-10 ns, each corresponding to the alkyl reorientation, the relaxation related to the imidazolium ring, and the ionic diffusion. The activation energy (Ea) for the alkyl relaxation is insensitive to both anion and alkyl chain lengths. On the other hand, for the imidazolium relaxation and the ionic diffusion processes, Ea increases as the anion size decreases but is almost independent of the alkyl chain length. This indicates that the ionic diffusion and imidazolium relaxation are governed by the Coulombic interaction between the core parts of the cations (imidazolium ring) and the anions. This is consistent with the fact that the imidazolium-based ILs have nanometer scale structures consisting of ionic and neutral (alkyl chain) domains. It is also found that there is a clear correlation between the ionic diffusion and viscosity, indicating that the ionic diffusion is mainly associated with the glass transition which is one of the characteristics of imidazolium-based ILs.

  8. Luminescent imidazolium carboxylate supported aggregate and infinite coordination networks of copper and zinc.

    PubMed

    Suresh, Paladugu; Radhakrishnan, Soumya; Naga Babu, Chatla; Sathyanarayana, Arruri; Sampath, Natarajan; Prabusankar, Ganesan

    2013-08-14

    The new copper dimer [LCu(DMF)]2(NO3)4(H2O)(DMF)2 (4), where L = [{1,1'-(CH2)2-C14H8)-3,3'-(CH2CO2)2}{(HCN)2CH}], and porous coordination polymers [{L2Cu(OH2)2}2Br2]x (5) and [{L2Zn(OH2)2}2Br2]x (6) have been isolated from reactions of luminescent imidazolium carboxylate ligand, LH2Br2 (3) and the corresponding metal precursors. The reaction between Cu(NO3)2·3H2O and LH2Br2 (3) in DMF at 100 °C yielded bluish green crystals of tetracationic discrete copper dimer 4, the structure of which contains a rare tetracationic [(DMF)Cu(ii)]2 dimer unit that is bridged by four carboxylates of two L in a "paddle-wheel" structure. When the reaction was carried out in the presence of a water-ethanol-methanol mixture, light green crystals of 5 were obtained. Molecule 5 comprises two-dimensional (2D) porous coordination polymeric sheets consisting of unique symmetrical dinuclear [(C(O)O)Cu(OH2)2(O(O)C)2]2 building blocks, which are connected by imidazolium anthracene spacers. The infinite 2D porous coordination polymeric sheets are further linked by significant intermolecular hydrogen-bonding interactions by bromide anions to form a three-dimensional supramolecular framework. Interestingly, the reaction between zinc dust and LH2Br2 (3) in H2O at room temperature gave similar structural features to those in 5, though they differ in terms of C-O bond distances and M-O-C angles. The solution-state UV-visible absorption spectra of 2-6 in water exhibits the comparable absorption pattern with decrease in the intensity of absorption from 5, 4, 3, 6 and 2, while the solid-state UV-visible absorption spectra of 2-6 are significantly different from the solution-state UV-visible absorption spectra. The considerable change in the fluorescent emission was observed upon complexation of 3 with corresponding metal precursors and the fluorescent emission was shifted towards the red region in the order of 2, 3, 6, 4 and 5 in water.

  9. Alkyl-imidazolium glycosides: non-ionic-cationic hybrid surfactants from renewable resources.

    PubMed

    Salman, Abbas Abdulameer; Tabandeh, Mojtaba; Heidelberg, Thorsten; Hussen, Rusnah Syahila Duali; Ali, Hapipah Mohd

    2015-08-14

    A series of surfactants combining carbohydrate and imidazolium head groups were prepared and investigated on their assembly behavior. The presence of the imidazolium group dominated the interactions of the surfactants, leading to high CMCs and large molecular surface areas, reflected in curved rather than lamellar surfactant assemblies. The carbohydrate, on the other hand, stabilized molecular assemblies slightly and reduced the surface tension of surfactant solutions considerably. A comparative emulsion study discourages the use of pure alkyl imidazolium glycosides owing to reduced assembly stabilities compared with APGs. However, the surfactants are believed to have potential as component in carbohydrate based surfactant mixtures. Copyright © 2015 Elsevier Ltd. All rights reserved.

  10. Influence of substituents on cation-anion contacts in imidazolium perrhenates.

    PubMed

    Reich, Robert M; Cokoja, Mirza; Markovits, Iulius I E; Münchmeyer, Christian J; Kaposi, Marlene; Pöthig, Alexander; Herrmann, Wolfgang A; Kühn, Fritz E

    2015-05-14

    A series of imidazolium perrhenates with different substituents at the imidazolium ring were synthesised and characterised, including single crystal X-ray diffraction. The effect of the substitution pattern on the state of aggregation of the compounds, the charge delocalisation and the ion pairing interaction via hydrogen bonds was studied. Particularly the substitution at the C2 position of the imidazolium ring was shown to be crucial to fine-tune the ion contacts. Fluorinated substituents appear to exhibit enhanced interionic interactions. The ability to tune the degree of contacts of the perrhenate anion allows for adjusting the nucleophilicity of this anion.

  11. Anti-tumor activity of lipophilic imidazolium salts on select NSCLC cell lines.

    PubMed

    Wright, Brian D; Deblock, Michael C; Wagers, Patrick O; Duah, Ernest; Robishaw, Nikki K; Shelton, Kerri L; Southerland, Marie R; DeBord, Michael A; Kersten, Kortney M; McDonald, Lucas J; Stiel, Jason A; Panzner, Matthew J; Tessier, Claire A; Paruchuri, Sailaja; Youngs, Wiley J

    2015-07-01

    The anti-tumor activity of imidazolium salts is highly dependent upon the substituents on the nitrogen atoms of the imidazolium cation. We have synthesized and characterized a series of naphthalene-substituted imidazolium salts and tested them against a variety of non-smallcell lung cancer cell lines. Several of these complexes displayed anticancer activity comparable to cisplatin. These compounds induced apoptosis in the NCI-H460 cell line as determined by Annexin V staining, caspase-3, and PARP cleavage. These results strongly suggest that this class of compounds can serve as potent chemotherapeutic agents.

  12. The Wetting Behavior of Imidazolium-Containing, Room-Temperature Molten Salt.

    DTIC Science & Technology

    1984-08-28

    from horizontal to vertical . The contact angles, tilt angles, and drop dimensions were observed through the glovebox window with a Gaertner...ethylimidazolium chloride plus aluminum chloride melts on glass. The wettability of battery component materials by other molten salto , such as lithium...YLV cosO (5) The best known example of the use of the adhesion tension is probably in the calculation of the height of rise of liquid in a vertical

  13. Room Acoustics

    NASA Astrophysics Data System (ADS)

    Kuttruff, Heinrich; Mommertz, Eckard

    The traditional task of room acoustics is to create or formulate conditions which ensure the best possible propagation of sound in a room from a sound source to a listener. Thus, objects of room acoustics are in particular assembly halls of all kinds, such as auditoria and lecture halls, conference rooms, theaters, concert halls or churches. Already at this point, it has to be pointed out that these conditions essentially depend on the question if speech or music should be transmitted; in the first case, the criterion for transmission quality is good speech intelligibility, in the other case, however, the success of room-acoustical efforts depends on other factors that cannot be quantified that easily, not least it also depends on the hearing habits of the listeners. In any case, absolutely "good acoustics" of a room do not exist.

  14. Gemini imidazolium surfactants: synthesis and their biophysiochemical study.

    PubMed

    Kamboj, Raman; Singh, Sukhprit; Bhadani, Avinash; Kataria, Hardeep; Kaur, Gurcharan

    2012-08-21

    New gemini imidazolium surfactants 9-13 have been synthesized by a regioselective epoxy ring-opening reaction under solvent-free conditions. The surface properties of these new gemini surfactants were evaluated by surface tension and conductivity measurements. These surfactants have been found to have low critical micelle concentration (cmc) values as compared to other categories of gemini cationic surfactants and also showed the tendency to form premicellar aggregates in solution at sufficiently low concentration below their cmc values. The thermal degradation of these surfactants was determined by thermograviometry analysis (TGA). These new cationic surfactants have a good DNA binding capability as determined by agarose gel electrophoresis and ethidium bromide exclusion experiments. They have also been found to have low cytotoxicity by MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) assay on the C6 glioma cell line.

  15. Gold nanoparticles stabilized with sulphonated imidazolium salts in water and reverse micelles

    PubMed Central

    Monti, Gustavo A.; Fernández, Gabriela A.; Correa, N. Mariano; Falcone, R. Darío; Moyano, Fernando

    2017-01-01

    Herein we describe the synthesis of gold nanoparticles (Au-NPs) in presence of sulphonated imidazolium salts [1,3-bis(2,6-diisopropyl-4-sodiumsulfonatophenyl)imidazolium (L1), 1-mesityl-3-(3-sulfonatopropyl)imidazolium (L2) and 1-(3-sulfonatopropyl)imidazolium (L3)] in water and in a confinement environment created by reverse micelles (RMs). The Au-NPs were characterized—with an excellent agreement between different techniques—by UV-vis spectroscopy, transmission electron microscopy (TEM), dynamic light scattering (DLS) and zeta potential. In homogeneous media, the Au-NPs interact with the imidazolium ring and the sulphonate groups were directed away from the NPs' surface. This fact is responsible for the Au-NPs' stability—over three months—in water. Based on the obtained zeta potential values we assume the degree of coverage of the Au-NPs by the imidazolium salts. In n-heptane/sodium 1,4-bis (2-ethylhexyl) sulfosuccinate (AOT)/water RMs, the Au-NPs formed in presence of sulphonated imidazolium salts present different patterns depending on the ligand used as stabilizer. Interestingly, the Au-NPs are more stable in time when the salts are present in AOT RMs (three weeks) in comparison with the same RMs system but in absence of ligands (less than an hour). Clearly, the sulphonated imidazolium salts are very effective Au-NPs stabilizers in a different medium and this generates a plus to be able to use them for multiple purposes. PMID:28791171

  16. Sulfate selective anion recognition by a novel tetra-imidazolium zinc metalloporphyrin receptor.

    PubMed

    Cormode, David P; Murray, Sean S; Cowley, Andrew R; Beer, Paul D

    2006-11-21

    Imidazolium groups have been successfully incorporated into the structure of a "picket fence" porphyrin molecule to produce a novel tetra-imidazolium zinc metalloporphyrin anion receptor. UV/visible spectroscopic studies reveal that this receptor is selective for sulfate anions, capable of strongly complexing sulfate in competitive water-DMSO (5 : 95) solvent mixtures. Cyclic and square wave voltammetric studies demonstrate the receptor's ability to sense a variety of anions electrochemically.

  17. Conjugated Polyelectrolytes with Imidazolium Solubilizing Groups. Properties and Application to Photodynamic Inactivation of Bacteria.

    PubMed

    Parthasarathy, Anand; Pappas, Harry C; Hill, Eric H; Huang, Yun; Whitten, David G; Schanze, Kirk S

    2015-12-30

    This article reports an investigation of the photophysical properties and the light- and dark-biocidal activity of two poly(phenyleneethynylene) (PPE)-based conjugated polyelectrolytes (CPEs) bearing cationic imidazolium solubilizing groups. The two polymers feature the same PPE-type backbone, but they differ in the frequency of imidazoliums on the chains: PIM-4 features two imidazolium units on every phenylene repeat, whereas PIM-2 contains two imidazolium units on every other phenylene unit. Both polymers are very soluble in water and polar organic solvents, but their propensity to aggregate in water differs with the density of the imidazolium units. The polymers are highly fluorescent, and they exhibit the amplified quenching effect when exposed to a low concentration of anionic electron-acceptor anthraquinone disulfonate. The CPEs are also quenched by a relatively low concentration of pyrophosphate by an aggregation-induced quenching mechanism. The biocidal activity of the cationic imidazolium CPEs was studied against both Gram-negative Escherichia coli and Gram-positive Staphylococcus aureus bacteria in the dark and under blue-light illumination. Both polymers are effective biocides, exhibiting greater than 3 log kill with 30-60 min of light exposure at concentrations of ≤10 μg mL(-1).

  18. Calix[n]imidazolium as a new class of positively charged homo-calix compounds.

    PubMed

    Chun, Young; Singh, N Jiten; Hwang, In-Chul; Lee, Jung Woo; Yu, Seong Uk; Kim, Kwang S

    2013-01-01

    Macrocycles based on neutral calixarenes and calixpyrroles have been extensively explored for ion binding, molecular assembly and related applications. Given that only these two types of calix compounds and their analogs are available, the introduction of new forms of widely usable calix macrocycles is an outstanding challenge. Here we report the quadruply/quintuply charged imidazole-based homo-calix compounds, calix[4/5]imidazolium. The noncovalent (C-H)(+)/π(+)-anion interactions of the imidazolium rings with anions inside and outside the cone are the stabilizing factors for crystal packing, resulting in self-assembled arrays of cone-shaped calix-imidazolium molecules. Calix[4]imidazolium senses fluoride selectively even in aqueous solutions. Calix[5]imidazolium recognizes neutral fullerenes through π(+)-π interactions and makes them soluble in water, which could be useful in fullerene chemistry. Not only derivatization and ring expansion of calix[n]imidazolium, but also their utilization in ionic liquids, carbene chemistry and nanographite/graphene exfoliation could be exploited.

  19. Periodic imidazolium-bridged hybrid monolith for high-efficiency capillary liquid chromatography with enhanced selectivity.

    PubMed

    Qiao, Xiaoqiang; Zhang, Niu; Han, Manman; Li, Xueyun; Qin, Xinying; Shen, Shigang

    2017-03-01

    A novel periodic imidazolium-bridged hybrid monolithic column was developed. With diene imidazolium ionic liquid 1-allyl-3-vinylimidazolium bromide as both cross-linker and organic functionalized reagent, a new periodic imidazolium-bridged hybrid monolithic column was facilely prepared in capillary with homogeneously distributed cationic imidazolium by a one-step free-radical polymerization with polyhedral oligomeric silsesquioxane methacryl substituted. The successful preparation of the new column was verified by Fourier transform infrared spectroscopy, scanning electron microscopy, elemental analysis, and surface area analysis. Most interestingly, the bonded amount of 1-allyl-3-vinylimidazolium bromide of the new column is three times higher than that of the conventional imidazolium-embedded hybrid monolithic column and the specific surface area of the column reached 478 m(2) /g. The new column exhibited high stability, excellent separation efficiency, and enhanced separation selectivity. The column efficiency reached 151 000 plates/m for alkylbenzenes. Furthermore, the new column was successfully used for separation of highly polar nucleosides and nucleic acid bases with pure water as mobile phase and even bovine serum albumin tryptic digest. All these results demonstrate the periodic imidazolium-bridged hybrid monolithic column is a good separation media and can be used for chromatographic separation of small molecules and complex biological samples with high efficiency.

  20. Effect of composition and nanostructure on CO2/N-2 transport properties of supported alkyl-imidazolium block copolymer membranes

    SciTech Connect

    Nguyen, PT; Wiesenauer, EF; Gin, DL; Noble, RD

    2013-03-01

    Polymerized room-temperature ionic liquids (poly(RTIL)s) have garnered attention as new and interesting membrane materials for CO2/light gas separations because they combine the high CO2 affinity and thermal and chemical stability of RTILs, with the physical and mechanical properties of polymeric materials. Our group recently synthesized a new type of block copolymer (BCP) combining an imidazolium-based poly(RTIL) and an alkyl non-ionic polymer. These alkyl-b-ionic BCPs phase-separate into ordered nanostructures. Prior work investigating gas transport through phase-separated BCPs is very limited, and none has included RTIL-based BCP systems. However it has been shown that nanoscale phase-separation could facilitate gas transport via nanostructure orientation control or phase connectivity improvement. We have successfully made defect-free, thin-film composite membranes with these novel alkyl-imidazolium BCPs as a 3-20 mu m thick top layer, and determined their CO2/N-2 separation properties via single-gas permeability measurements and selectivity calculations. These new BCP materials were found to have distinct advantages over the analogous physical blends of the parent homopolymers with respect to membrane fabrication. The composition of the BCP top layer, which is directly connected to the type of nanostructure formed, was found to have a significant effect on CO2 permeability (i.e., it can increase CO2 permeability by two orders of magnitude up to an observed value of 9300 barrer). This improvement is mainly due to a large increase in the diffusion coefficient in the ordered nanostructures compared to amorphous BCP materials. (C) 2012 Elsevier B.V. All rights reserved.

  1. Local structure and molecular motions in imidazolium hydrogen malonate crystal as studied by 2H and 13C NMR

    NASA Astrophysics Data System (ADS)

    Mizuno, M.; Chizuwa, M.; Umiyama, T.; Kumagai, Y.; Miyatou, T.; Ohashi, R.; Ida, T.; Tansho, M.; Shimizu, T.

    2015-04-01

    The local structure and molecular motion of the imidazolium hydrogen malonate crystal were investigated using solid-state 2H and 13C NMR. The imidazolium ion undergoes isotropic rotation, which is correlated with a defect in the crystal, as observed by 2H NMR broadline spectra above 263 K. A 180∘ flip of the imidazolium ion in the regular site was observed from 2H NMR quadrupole Carr-Purcell-Meiboom-Gill (QCPMG) spectra. The Grotthuss mechanism was accompanied by a 180∘ flip of the imidazolium ion in regular sites. Moreover, the proton transfer associated with the imidazolium ion of the defective crystal is important for proton conductivity of the imidazolium hydrogen malonate crystal.

  2. Atomic Resolution Insights into the Structural Aggregations and Optical Properties of Neat Imidazolium-Based Ionic Liquids.

    PubMed

    Du, Likai; Geng, Cuihuan; Zhang, Dongju; Lan, Zhenggang; Liu, Chengbu

    2016-07-14

    A fundamental understanding of the structural heterogeneity and optical properties of ionic liquids is crucial for their potential applications in catalysis, optical measurement, and solar cells. Herein, a synergistic approach combining molecular dynamics simulations, excited-state calculations, and statistical analysis was used to explore the explicit correlation between the structural and optical properties of one imidazolium amino acid-based ionic liquid, 1-butyl-3-methylimidazolium glycine. The estimated absorption spectrum successfully rationalizes the unusual and non-negligible absorption band beyond 300 nm for the neat imidazolium-based ionic liquid. The absorption behavior of imidazolium-based ionic liquids is shown to be sensitive to the details of their locally heterogeneous environments. We quantitatively highlight the imidazolium moiety and its various molecular aggregations, rather than the monomeric imidazolium moiety, that are responsible for the absorption characteristics. These results would improve our understanding of the preliminary interplay between structural heterogeneity and optical properties for neat imidazolium-based ionic liquids.

  3. Dihalo(imidazolium)sulfuranes: A Versatile Platform for the Synthesis of New Electrophilic Group-Transfer Reagents.

    PubMed

    Talavera, Garazi; Peña, Javier; Alcarazo, Manuel

    2015-07-15

    The syntheses of imidazolium thiocyanates and imidazolium thioalkynes from dihalo(imidazolium) sulfuranes are reported and their reactivities as CN(+) and R-CC(+) synthons evaluated, respectively. The easy and scalable preparation of these electrophilic reagents, their operationally simple handling, broad substrate scope, and functional group tolerance clearly illustrate the potential of these species to become a reference for the direct electrophilic cyanation and alkynylation of organic substrates.

  4. Crystallization control of SrCO{sub 3} nanostructure in imidazolium-based temperature ionic liquids

    SciTech Connect

    Li, Lishuo; Lin, Rongyi; Tong, Zhangfa; Feng, Qingge

    2012-11-15

    Highlights: ► Nanowhisker, nanospindle, nanosphere, sphere, spindle, rodlike SrCO{sub 3} were obtained. ► Nanowhisker, nanospindle SrCO{sub 3} were auto-assembled in [C{sub 8}mim]BF{sub 4} and [HOEtMIm]NT{sub f2}. ► Small size and rough surface particle show low starting decomposition temperature. ► This method is simple, easy to control in large-scale producing SrCO{sub 3} nanostructure. -- Abstract: Strontium carbonate nanostructures, with unique nanowhisker, nanospindle, nanosphere, sphere, spindle, and rodlike hierarchical structure, were synthesized in imidazolium-based room temperature ionic liquids [C{sub 4}mim]PF{sub 6}, [C{sub 4}mim]Cl, [C{sub 8}mim]Br, [C{sub 8}mim]BF{sub 4}, and [HOEtMIm]NT{sub f2}. The nanostructures were characterized by X-ray diffraction, field emission scanning electron microscopy, transmission electron microscopy, and thermogravimetric analysis. The results show that the morphologies of SrCO{sub 3} were strongly dependent on the nature of the corresponding RILs, its content, and the reaction temperature. RILs can act as structure-directing agent, leading the auto-assembly of SrCO{sub 3} crystal. [C{sub 8}mim]BF{sub 4} and [HOEtMIm]NT{sub f2} favored the production of nanowhisker and nanospindle SrCO{sub 3}, respectively, whereas [C{sub 4}mim]PF{sub 6} favored the production of nanosphere. Small particles were obtained at high reaction temperature. Low starting decomposition temperature was observed. Finally, the formation mechanism of the SrCO{sub 3} crystal was preliminary presented.

  5. Experimental and Quantum Chemical Calculations of Imidazolium Appended Naphthalene Hybrid in Different Biomimicking Aqueous Interfaces.

    PubMed

    Yenupuri, Tej Varma; Mydlova, Lucia; Agarwal, Devesh S; Sharma, Ritika; Sakhuja, Rajeev; Makowska-Janusik, Malgorzata; Pant, Debi D

    2016-08-25

    The effect of solvent polarity and micellar headgroup on a newly designed imidazolium based ionic liquid (IL) conjugated with naphthalene, 1,2-dimethyl-3-((6-(octyloxy)naphthalen-2-yl)methyl)-1H-imidazol-3-ium chloride (IN-O8-Cl), was studied using steady state and time-resolved fluorescence techniques. We observed that the dipole moment in the excited state is remarkably higher than the ground state. The effect of micellar surface charge on the photophysics of IN-O8-Cl in aqueous phase at room temperature was investigated. Formation of premicellar aggregates in sodium dodecylsulfate (SDS) was perceived; further the microenvironment of IN-O8-Cl was examined using steady-state fluorescence spectroscopy. Micropolarity of the micellar environment of SDS was found to be lower than that of cetyltrimethylammonium bromide (CTAB) and triton X-100 (TX100) following the order SDS < TX-100 < CTAB. The binding constant (Kb) and edge excitation red shift (EERS) from the emission maximum suggest that the probe binds strongly to the micelles. Multiexponential behavior was observed in time-resolved fluorescence lifetime studies in all micellar environments. We have observed an increase in rotational correlation time as we move from pure aqueous phase to solution containing surfactants of different head charge. Varieties of spectral parameters were used to justify the region in which the probe is present. The experimentally obtained dipole moment data were justified and explained by the DFT calculations of the electronic properties of IN-O8-Cl molecules in gas phase and in selected solvents.

  6. Imidazolium salts with antifungal potential against multidrug-resistant dermatophytes.

    PubMed

    Dalla Lana, D F; Donato, R K; Bündchen, C; Guez, C M; Bergamo, V Z; de Oliveira, L F S; Machado, M M; Schrekker, H S; Fuentefria, A M

    2015-08-01

    To investigate the antidermatophytic action of a complementary set imidazolium salts (IMS), determining structure-activity relationships and characterizing the IMS toxicological profiles. The susceptibility evaluation of 45 dermatophytic clinical isolates, treated in vitro with eleven different IMS (ionic compounds) and commercial antifungals (nonionic compounds), was performed by broth microdilution, following the standard norm of CLSI M38-A2. All dermatophytes were inhibited by IMS, where the lowest minimum inhibitory concentration (MIC) values were observed for salts with n-hexadecyl segment in the cation side chain, containing either the chloride or methanesulfonate anion. 1-n-Hexadecyl-3-methylimidazolium chloride (C16 MImCl) and 1-n-hexadecyl-3-methylimidazolium methanesulfonate (C16 MImMeS) acted as fungicides, even in extremely low concentrations, wherein C16 MImMeS exerted this effect on 100% of the tested dermatophytes. Some of these IMS provoked evident alterations on the fungi cell morphology, causing a total cell damage of ≥ 70%. Importantly, none of the screened IMS were cytotoxic, mutagenic or genotoxic to human leucocyte cells. This report demonstrates for the first time the strong antifungal potential of IMS against multidrug-resistant dermatophytes, without presenting toxicity to human leucocyte cells at MIC. The expressive antifungal activity of IMS, combined with the in vitro nontoxicity, makes them promising compounds for the safe and effective treatment of dermatophytoses, mainly when this skin mycosis is unresponsive to conventional drugs. © 2015 The Society for Applied Microbiology.

  7. Small iron-carbonyl clusters bearing imidazolium-2-trithioperoxycarboxylate ligands.

    PubMed

    Beltrán, Tomás F; Zaragoza, Guillermo; Delaude, Lionel

    2017-10-14

    The reaction of [Fe2(CO)9] with two representative imidazolium-2-dithiocarboxylate zwitterions derived from common N-heterocyclic carbenes (NHCs) bearing mesityl (IMes) or 2,6-diisopropylphenyl substituents on their nitrogen atoms (IDip) unexpectedly afforded two small bimetallic iron-carbonyl clusters with the generic formula [Fe2(CO)6(μ-κ(2)-S,S'-κ(2)-S,S'-S3C·NHC)]. After a brief optimization of the reaction conditions, these two "sulfur-enriched" products were isolated in low yields. They were fully characterized by IR, NMR, UV/Visible, and ESI-MS techniques, and their molecular structures were determined by single crystal X-ray diffraction analysis. The two compounds adopted a butterfly-type disposition in the solid state, with an [Fe2(CO)6] core bridged by the trithioperoxycarboxylate moiety of the in situ generated NHC·CS3 ligands. Bond lengths recorded for the CS3(-) unit revealed that its negative charge was mostly located on the remote sulfur atom.

  8. Physical Properties of Substituted Imidazolium Based Ionic Liquids Gel Electrolytes

    NASA Astrophysics Data System (ADS)

    Sutto, Thomas E.; De Long, Hugh C.; Trulove, Paul C.

    2002-11-01

    The physical properties of solid gel electrolytes of either polyvinylidene diflurohexafluoropropylene or a combination of polyvinylidene hexafluoropropylene and polyacrylic acid, and the molten salts 1-ethyl-3-methylimidazolium tetrafluoroborate, 1,2-dimethyl-3-n-propylimidazolium tetrafluoroborate, and the new molten salts 1,2-dimethyl-3-n-butylimidazolium tetrafluoroborate, and 1,2-dimethyl-3-n-butylimidazolium hexafluorophosphate were characterized by temperature dependent ionic conductivity measurements for both the pure molten salt and of the molten salt with 0.5 M Li+ present. Ionic conductivity data indicate that for each of the molten salts, the highest concentration of molten salt allowable in a single component polymer gel was 85%, while gels composed of 90%molten salt were possible when using both polyvinylidene hexafluorophosphate and polyacrylic acid. For polymer gel composites prepared using lithium containing ionic liquids, the optimum polymer gel composite consisted of 85% of the 0.5 M Li+/ionic liquid, 12.75% polyvinylidene hexafluoropropylene, and 2.25% poly (1-carboxyethylene). The highest ionic conductivity observed was for the gel containing 90%1-ethyl-3-methyl-imidazolium tetrafluoroborate, 9.08 mS/cm. For the lithium containing ionic liquid gels, their ionic conductivity ranged from 1.45 to 0.05 mS/cm, which is comparable to the value of 0.91 mS/cm, observed for polymer composite gels containing 0.5 M LiBF4 in propylene carbonate.

  9. Memory's Room.

    ERIC Educational Resources Information Center

    Carruthers, Mary

    1999-01-01

    Describes the Liberal Arts Studiolo from the Ducal Palace at Guibbio, Italy. Discusses how the room's design and decoration mirrors its educational uses. Notes that the object of education was to provide the young person with a kind of mental library of materials that could be drawn upon quickly. (RS)

  10. Memory's Room.

    ERIC Educational Resources Information Center

    Carruthers, Mary

    1999-01-01

    Describes the Liberal Arts Studiolo from the Ducal Palace at Guibbio, Italy. Discusses how the room's design and decoration mirrors its educational uses. Notes that the object of education was to provide the young person with a kind of mental library of materials that could be drawn upon quickly. (RS)

  11. Ordered, microphase-separated, noncharged-charged diblock copolymers via the sequential ATRP of styrene and styrenic imidazolium monomers

    SciTech Connect

    Shi, ZX; Newell, BS; Bailey, TS; Gin, DL

    2014-12-15

    A series of imidazolium-based noncharged-charged diblock copolymers (1) was synthesized by the direct, sequential ATRP of styrene and styrenic imidazolium bis(trifluoromethyl)sulfonamide monomers with methyl, n-butyl, and n-decyl side-chains. Small-angle X-ray scattering studies on initial examples of 1 with a total of 50 repeat units and styrene:imidazolium-styrene repeat unit ratios of 25:25, 20:30, and 15:35 showed that their ability to form ordered nanostructures (i.e., sphere and cylinder phases) in their neat states depends on both the block ratio and the length of the alkyl side-chain on the imidazolium monomer. To our knowledge, the synthesis of imidazolium-based BCPs that form ordered, phase-separated nanostructures via direct ATRP of immiscible co-monomers is unprecedented. (C) 2014 Elsevier Ltd. All rights reserved.

  12. Thermally stable organically modified layered silicates based on alkyl imidazolium salts.

    PubMed

    Goswami, Shailesh K; Ghosh, Smita; Mathias, Lon J

    2012-02-15

    A series of imidazolium salts having various substituents and functional groups were synthesized and characterized by FTIR and NMR spectroscopy. Organic modification of natural and synthetic layered silicates involving montmorillonite (MMT), laponite (lap), and synthetic mica (mica) was carried out by ion-exchange reaction. The obtained organo-clays were characterized by FTIR and powder X-ray diffraction techniques. Results indicate that these organically modified clays have much higher thermal stabilities compared to their corresponding imidazolium halides. It was also observed from TGA analysis that thermal stability does not depend on the functional group present at the 3-position of the imidazolium salts. These studies strongly supports premise that the removal of halide is necessary to improve the thermal stability of the organo-clay produced.

  13. Molecular Dynamics Simulations of Amide Functionalized Imidazolium Bis(trifluoromethanesulfonyl)imide Dicationic Ionic Liquids.

    PubMed

    Khakan, Hassan; Yeganegi, Saeid

    2017-08-10

    In the present study, the structure and dynamics of three dicationic ionic liquids (DILs) with a functional amide group in the imidazolium ring with bis(trifluoromethanesulfonyl)imide, [TFSI](-) anion has been studied by molecular dynamics (MD) simulations. Densities, radial distribution functions (RDFs), combined distribution functions (CDFs), spatial distribution functions, mean-square displacements (MSD), and self-diffusivities for the ions have been calculated from the MD simulations. The calculated densities for [C4(amim)2][TFSI]2 at different temperatures agreed well with the experimental values. The calculated RDFs and CDFs show that the anions are well organized around the amide group and imidazolium rings and the favorite sites of interaction of the [TFSI](-) ion are the hydrogen atoms of the amide group and hydrogen atoms of the imidazolium ring of the cation. The calculated MSDs indicated that the diffusion coefficients of the studied DILs are 1 order of magnitude smaller than those of DILs with a comparable molar mass.

  14. Imidazolium based probes for recognition of biologically and medically relevant anions.

    PubMed

    Kumar, Rahul; Sandhu, Sana; Singh, Prabhpreet; Kumar, Subodh

    2016-10-14

    The imidazolium derivatives due to their positive charge possess one of the most polarized and positively charged proton at C2-H to form strong ionic hydrogen bond (also termed as double ionic hydrogen bond) with anions and also provide opportunities for anion - π interactions with electron-deficient imidazolium ring. In the present review article, imidazolium based molecular probes for their ability to recognize inorganic anions like halides, cyanide, perchlorate, carboxylic acids, phosphate, sulfate etc. and their derived molecules viz. nucleotides, DNA, RNA, surfactants, proteins, etc have been discussed. The review covers the literature published after year 2009 and has > 130 references. The previous literature has already been discussed by Yoon et al in two review articles published in Chem. Soc. Rev. 2006 and 2010.

  15. Imidazolium Cations with Exceptional Alkaline Stability: A Systematic Study of Structure-Stability Relationships.

    PubMed

    Hugar, Kristina M; Kostalik, Henry A; Coates, Geoffrey W

    2015-07-15

    Highly base-stable cationic moieties are a critical component of anion exchange membranes (AEMs) in alkaline fuel cells (AFCs); however, the commonly employed organic cations have limited alkaline stability. To address this problem, we synthesized and characterized the stability of a series of imidazolium cations in 1, 2, or 5 M KOH/CD3OH at 80 °C, systematically evaluating the impact of substitution on chemical stability. The substituent identity at each position of the imidazolium ring has a dramatic effect on the overall cation stability. We report imidazolium cations that have the highest alkaline stabilities reported to date, >99% cation remaining after 30 days in 5 M KOH/CD3OH at 80 °C.

  16. Neighbor-directed histidine N(τ) alkylation. A route to imidazolium-containing phosphopeptide macrocycles

    SciTech Connect

    Qian, Wen-Jian; Park, Jung-Eun; Grant, Robert; Lai, Christopher C.; Kelley, James A.; Yaffe, Michael B.; Lee, Kyung S.; Burke, Terrence R.

    2015-07-07

    Our recently discovered, selective, on-resin route to N(τ)-alkylated imidazolium-containing histidine residues affords new strategies for peptide mimetic design. In this, we demonstrate the use of this chemistry to prepare a series of macrocyclic phosphopeptides, in which imidazolium groups serve as ring-forming junctions. These cationic moieties subsequently serve to charge-mask the phosphoamino acid group that directed their formation. Furthermore, neighbor-directed histidine N(τ)-alkylation opens the door to new families of phosphopeptidomimetics for use in a range of chemical biology contexts.

  17. Imidazolium-Based Lipid Analogues and Their Interaction with Phosphatidylcholine Membranes.

    PubMed

    Wang, Da; de Jong, Djurre H; Rühling, Andreas; Lesch, Volker; Shimizu, Karina; Wulff, Stephanie; Heuer, Andreas; Glorius, Frank; Galla, Hans-Joachim

    2016-12-06

    4,5-Dialkylated imidazolium lipid salts are a new class of lipid analogues showing distinct biological activities. The potential effects of the imidazolium lipids on artificial lipid membranes and the corresponding membrane interactions was analyzed. Therefore, 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC) was employed to create an established lipid monolayer model and a bilayer membrane. Mixed monolayers of DPPC and 4,5-dialkylimidazolium lipids differing by their alkyl chain length (C7, C11, and C15) were characterized by surface pressure-area (π-A) isotherms using a Wilhelmy film balance in combination with epifluorescence microscopy. Monolayer hysteresis for binary mixtures was examined by recording triplicate consecutive compression-expansion cycles. The lipid miscibility and membrane stability of DPPC/imidazolium lipids were subsequently evaluated by the excess mean molecular area (ΔA(ex)) and the excess Gibbs free energy (ΔG(ex)) of mixing. Furthermore, the thermotropic behavior of mixed liposomes of DPPC/imidazolium lipids was investigated by differential scanning calorimetry (DSC). The C15-imidazolium lipid (C15-IMe·HI) forms a thermodynamically favored and kinetically reversible Langmuir monolayer with DPPC and exhibits a rigidification effect on both DPPC monolayer and bilayer structures at low molar fractions (X ≤ 0.3). However, the incorporation of the C11-imidazolium lipid (C11-IMe·HI) causes the formation of an unstable and irreversible Langmuir-Gibbs monolayer with DPPC and disordered DPPC liposomes. The C7-imidazolium lipid (C7-IMe·HI) displays negligible membrane activity. To better understand these results on a molecular level, all-atom molecular dynamics (MD) simulations were performed. The simulations yield two opposing molecular mechanisms governing the different behavior of the three imidazolium lipids: a lateral ordering effect and a free volume/stretching effect. Overall, our study provides the first evidence that the membrane

  18. Neighbor-directed histidine N (τ)-alkylation: A route to imidazolium-containing phosphopeptide macrocycles.

    PubMed

    Qian, Wen-Jian; Park, Jung-Eun; Grant, Robert; Lai, Christopher C; Kelley, James A; Yaffe, Michael B; Lee, Kyung S; Burke, Terrence R

    2015-11-01

    Our recently discovered, selective, on-resin route to N(τ)-alkylated imidazolium-containing histidine residues affords new strategies for peptide mimetic design. In this, we demonstrate the use of this chemistry to prepare a series of macrocyclic phosphopeptides, in which imidazolium groups serve as ring-forming junctions. Interestingly, these cationic moieties subsequently serve to charge-mask the phosphoamino acid group that directed their formation. Neighbor-directed histidine N(τ)-alkylation opens the door to new families of phosphopeptidomimetics for use in a range of chemical biology contexts.

  19. Imidazolium-based ionic liquids grafted on solid surfaces.

    PubMed

    Xin, Bingwei; Hao, Jingcheng

    2014-01-01

    Supported ionic liquids (SILs), which refer to ionic liquids (ILs) immobilized on supports, are among the most important derivatives of ILs. The immobilization process of ILs can transfer their desired properties to substrates. Combination of the advantages of ILs with those of support materials will derive novel performances while retaining properties of both moieties. SILs have been widely applied in almost all of fields involving ILs, and have brought about drastic expansion of the ionic liquid area. As green media in organic catalytic reactions, based on utilizing the ability of ILs to stabilize the catalysts, they have many advantages over free ILs, including avoiding the leaching of ILs, reducing their amount, and improving the recoverability and reusability of both themselves and catalysts. This has critical significance from both environmental and economical points of view. As novel functional materials in surface science and material chemistry, SILs are ideal surface modifying agents. They can modify and improve the properties of solids, such as wettability, lubricating property, separation efficiency and electrochemical response. With the achievements in the field of ILs, using magnetic nanoparticles (MNPs) to SILs has drawn increasing attention in catalytic reactions and separation technologies, and achieved substantial progress. The combination of MNPs and ILs renders magnetic SILs, which exhibit the unique properties of ILs as well as facile separation by an external magnetic field. In this article, we focus on imidazolium-based ILs covalently grafted to non-porous and porous inorganic materials. The excellent stability and durability of this kind of SILs offer a great advantage compared with free ILs and IL films physically adsorbed on substrates without covalent bonds. Including examples from our own research, we overview mainly the applications and achievements of covalent-linked SILs in catalytic reactions, surface modification, separation

  20. Photoinduced electron transfer in an imidazolium ionic liquid and in its binary mixtures with water, methanol, and 2-propanol: appearance of Marcus-type of inversion.

    PubMed

    Sarkar, Souravi; Mandal, Sarthak; Ghatak, Chiranjib; Rao, Vishal Govind; Ghosh, Surajit; Sarkar, Nilmoni

    2012-02-02

    The photoinduced electron transfer (PET) reaction has been investigated in a room temperature imidazolium ionic liquid (RTIL), 1-ethyl-3-methylimidazolium ethyl sulfate ([Emim][EtSO(4)]) and also in [Emim][EtSO(4)]-co-solvents mixtures from N,N-dimethyl aniline (DMA) to different Coumarin dyes using steady state and time-resolved fluorescence quenching measurements. We have used water and methanol and 2-propanol as the cosolvents of RTILs for the PET study. On going from neat ionic liquid to the RTIL-co-solvents mixtures the electron transfer rate has been largely enhanced. In neat RTIL as well as in [Emim][EtSO(4)]-co-solvents mixtures, a Marcus type of inversion in the PET rate have been observed.

  1. Effects of bis(imidazolium) molten salts with different substituents of imidazolium cations on the performance of efficient dye-sensitized solar cells.

    PubMed

    Bai, Sihang; Bu, Chenghao; Tai, Qidong; Liang, Liangliang; Liu, Yumin; You, Sujian; Yu, Zhenhua; Guo, Shishang; Zhao, Xingzhong

    2013-04-24

    Bis(imidazolium) iodides (bis-Im(+)I(-)s) are synthesized with different substituents and used as electrolytes in dye-sensitized solar cells (DSSCs). Three kinds of low-volatility electrolytes are prepared by using 1,1'-methylene bis(3-imidazolium) diiodide (MIDI), 1,1'-methylene bis(3-n-methylimidazolium) diiodide (MMIDI), and 1,1'-methylene-bis(3-n-ethylimidazolium) diiodide (MEIDI) as the iodide sources. The effects of these substituents on the photovoltaic performance of the cells are investigated. It is found that the device shows a lower short-circuit photocurrent (Jsc), higher open-voltage (Voc) and fill factor (FF) with the increased cation size in electrolyte. These results are explained by electrostatic interactions between the solvated Im(+) and the negatively charged species. Meanwhile, the explanation is supported by electrochemical impedance spectroscopy (EIS), cyclic voltammetry (CV), open circuit voltage decay (OCVD), and dark current measurements.

  2. Calorimetric and Neutron Scattering Studies on Glass Transitions and Ionic Diffusions in Imidazolium-based Ionic Liquids

    NASA Astrophysics Data System (ADS)

    Yamamuro, O.; Kofu, M.

    2017-05-01

    Glass transition is one of the central research issues of ionic liquids (ILs). In particular, the most typical ILs, imidazolium-basedones (ImILs) are readily supercooled and exhibit glass transitions below room temperature. We have measured the heat capacities of several ImILs, encoded as CnmimX (n: alkyl carbon number, n = 2-8, X: anion, X = Cl, I, FeCl4, TFSI) using an adiabatic calorimeter. We found that most of ImILs exhibit glass transitions with large Cp jumps in a temperature range between 170 K and 230 K. The large Cp jumps reflect that these ILs are fragile liquids that exhibit large structural change depending on temperature near the glass transition temperature T g. It is also revealed that T g does not depend much on n but on the anion radius. We have investigated the dynamics of CnmimX (n = 2-8, X = Cl, NO3, PF6, TF, FSI, TFSI) by means of a quasielastic neutron scattering (QENS) technique. It was clarified that the ionic diffusion is directly associated with the viscosity and glass transition. The activation energy ΔE a of the ionic diffusion increases with decreasing anion size but remains almost unchanged with n as found for T g. These systematic change of T g and ΔE a can be explained well by taking account the nano-domain structure which is the most characteristic feature of ImILs.

  3. Basement utility room (room 24; air handling room), near the ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    Basement utility room (room 24; air handling room), near the west end of the combat operations center, looking southwest towards fan system one, air ducts, and walk-in filter rooms. The exterior equipment well is visible at the left - March Air Force Base, Strategic Air Command, Combat Operations Center, 5220 Riverside Drive, Moreno Valley, Riverside County, CA

  4. Effect of water on structure of hydrophilic imidazolium-based ionic liquid.

    PubMed

    Takamuku, Toshiyuki; Kyoshoin, Yasuhiro; Shimomura, Takuya; Kittaka, Shigeharu; Yamaguchi, Toshio

    2009-08-06

    The state of water in room-temperature ionic liquid, 1-ethyl-3-methylimidazolium tetrafluoroborate (EMI(+)BF(4)(-)), has been investigated by measurements of absorption and desorption isotherms, attenuated total reflectance infrared (ATR-IR) spectroscopy, and (2)H NMR relaxation method. The absorption enthalpies of water for the ionic liquid were estimated from the absorption isotherms. The enthalpies in the water mole fraction range of x(w) approximately 0.3. In addition, the activation energies for the rotational motion of a water molecule estimated from the (2)H NMR relaxation rates have indicated that the motion of water molecules in EMI(+)BF(4)(-)-D(2)O solutions gradually becomes freer with increasing water content from x(w) = 0.10 to 0.30, but is retarded again at x(w) = 0.33. Therefore, all the present findings have suggested that the state of water molecules in EMI(+)BF(4)(-) significantly changes at x(w) approximately 0.3. On the other hand, to directly observe the effect of water on structure of EMI(+)BF(4)(-), LAXS experiments have been made on EMI(+)BF(4)(-)-water solutions. It has been suggested that the interactions between the C(2) atom within the imidazolium ring of EMI(+) and BF(4)(-) are strengthened with increasing water content, while those at the C(4) and C(5) atoms weaken. Thus, the present LAXS experiments have clarified the beginning of formation of ion pair in EMI(+)BF(4)(-) by adding water at the molecular level.

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

    NASA Astrophysics Data System (ADS)

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

    2008-12-01

    Molecular dynamics simulations are used to study the dynamics and transport properties of 12 room-temperature ionic liquids of the 1-alkyl-3-methylimidazolium [amim]+ (alkyl=methyl, ethyl, propyl, and butyl) family with PF6-, NO3-, and Cl- counterions. The explicit atom transferable force field of Canongia Lopes et al. [J. Phys. Chem. B 108, 2038 (2004)] is used in the simulations. In this first part, the dynamics of the ionic liquids are characterized by studying the mean-square displacement (MSD) and the velocity autocorrelation function (VACF) for the centers of mass of the ions at 400 K. Trajectory averaging was employed to evaluate the diffusion coefficients at two temperatures from the linear slope of MSD(t) functions in the range of 150-300 ps and from the integration of the VACF(t) functions at 400 K. Detailed comparisons are made between the diffusion results from the MSD and VACF methods. The diffusion coefficients from the integration of the VACFs are closer to experimental values than the diffusion coefficients calculated from the slope of MSDs. Both methods can show good agreement with experiment in predicting relative trends in the diffusion coefficients and determining the role of the cation and anion structures on the dynamical behavior of this family of ionic liquids. The MSD and self-diffusion of relatively heavier imidazolium cations are larger than those of the lighter anions from the Einstein results, except for the case of [bmim][Cl]. The cationic transference number generally decreases with temperature, in good agreement with experiments. For the same anion, the cationic transference numbers decrease with increasing length of the alkyl chain, and for the same cation, the trends in the cationic transference numbers are [NO3]-<[Cl]-<[PF6]-. The trends in the diffusion coefficient in the series of cations with identical anions are [emim]+>[pmim]+>[bmim]+ and those for anions with identical cations are [NO3]->[PF6]->[Cl]-. The [dmim]+ has a

  6. Imidazolium-tagged glycan probes for non-covalent labeling of live cells.

    PubMed

    Benito-Alifonso, David; Tremell, Shirley; Sadler, Joanna C; Berry, Monica; Galan, M Carmen

    2016-04-07

    Selective, bioorthogonal and fast labeling of glycoconjugates in living cells is a major challenge for synthetic and cellular biology. Here we report the use imidazolium tagged-mannosamine derivative (ITag-Man) for the non-covalent, rapid and site-specific labeling of sialic acid containing glycoproteins using commercial N-nitrilotriacetate fluorescent reagents in a range of cell lines.

  7. Imidazolium tagged acridines: Synthesis, characterization and applications in DNA binding and anti-microbial activities

    NASA Astrophysics Data System (ADS)

    Raju, Gembali; Vishwanath, S.; Prasad, Archana; Patel, Basant K.; Prabusankar, Ganesan

    2016-03-01

    New water soluble 4,5-bis imidazolium tagged acridines have been synthesized and structurally characterized by multinuclear NMR and single crystal X-ray diffraction techniques. The DNA binding and anti-microbial activities of these acridine derivatives were investigated by fluorescence and far-UV circular dichroism studies.

  8. Decomposition of Imidazolium-Based Ionic Liquids in Contact with Lithium Metal.

    PubMed

    Schmitz, Paulo; Jakelski, Rene; Pyschik, Marcelina; Jalkanen, Kirsi; Nowak, Sascha; Winter, Martin; Bieker, Peter

    2017-03-09

    Ionic liquids (ILs) are considered to be suitable electrolyte components for lithium-metal batteries. Imidazolium cation based ILs were previously found to be applicable for battery systems with a lithium-metal negative electrode. However, herein it is shown that, in contrast to the well-known IL N-butyl-N-methylpyrrolidinium bis[(trifluoromethyl)sulfonyl]imide ([Pyr14 ][TFSI]), 1-ethyl-3-methylimidazolium bis[(trifluoromethyl)sulfonyl]imide ([C2MIm][TFSI]) and 1-butyl-3-methylimidazolium bis[(trifluoromethyl)sulfonyl]imide ([C4MIm][TFSI]) are chemically unstable versus metallic lithium. A lithium-metal sheet was immersed in pure imidazolium-based IL samples and aged at 60 °C for 28 days. Afterwards, the aged IL samples were investigated to deduce possible decomposition products of the imidazolium cation. The chemical instability of the ILs in contact with lithium metal and a possible decomposition starting point are shown for the first time. Furthermore, the investigated imidazolium-based ILs can be utilized for lithium-metal batteries through the addition of the solid-electrolyte interphase (SEI) film-forming additive fluoroethylene carbonate. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  9. Alkyl imidazolium ionic-liquid-mediated formation of gold particle superstructures.

    PubMed

    Ji, Qingmin; Acharya, Somobrata; Richards, Gary J; Zhang, Shaoling; Vieaud, Julien; Hill, Jonathan P; Ariga, Katsuhiko

    2013-06-18

    The development of new methodologies for controlling the organization of quantum materials in multiple dimensions is crucial to the advancement of device fabrication. By using a self-assembly route using selected imidazolium ionic liquids bearing long alkyl chains (C(n)Imida, n = 8, 10, 12) as ligands, we have achieved a tunable assembly of quantum-sized gold nanoparticles. The initial stabilizer of the gold nanoparticles was partially or wholly substituted depending on the concentration and alkyl chain length. π-π interactions between imidazolium rings also promote the generation of spatially controlled aggregates from the nanometer to micrometer size regimes. In particular, in the case of an imidazolium ionic liquid with decyl chains, gold particles assemble into a core-shell spherical superstructure induced by the aggregation of imidazolium ionic liquid molecules during ligand exchange. Conceptually, the assemblies of nanoparticles mimic biological systems and provide strategies for the organization of single-component nanomaterials into functional assemblies for potential applications. Our approach is general and can be applied to other types of nanomaterials for facile manipulation of the assembly processes, permitting an exploration of physicochemical properties as well as technological applications.

  10. Properties of Apolar Solutes in Alkyl Imidazolium-Based Ionic Liquids: The Importance of Local Interactions.

    PubMed

    Lesch, Volker; Heuer, Andreas; Holm, Christian; Smiatek, Jens

    2016-02-03

    The solvation and the dynamic properties of apolar model solutes in alkyl imidazolium-based ionic liquids (IL) are studied by using all-atom molecular dynamics simulations. In regards to specific IL effects, we focused on the often used 1-ethyl-3-methyl imidazolium cation in combination with the anions tetrafluoroborate, acetate, and bis(trifluoromethanesulfonyl)imide. Our findings reveal that the size of the anion crucially influences the accumulation behavior of the cations, which results in modified IL solvation properties. Deviations between the different alkyl imidazolium-based IL combinations can be also observed with regard to the results for the radial distribution functions, the number of surrounding molecules, and the molecular orientation. The analysis of the van Hove function further shows pronounced differences in the dynamic behavior of the solutes. The simulations verify that the solute mobilities are mainly influenced by the composition of the local solvent shell and the properties of the underlying Lennard-Jones interactions. Additional simulations with regard to modified short-range dispersion energies for alkyl imidazolium-based ILs validate our conclusions.

  11. Dynamic response of a thin sessile drop of conductive liquid to an abruptly applied or removed electric field.

    PubMed

    Corson, L T; Mottram, N J; Duffy, B R; Wilson, S K; Tsakonas, C; Brown, C V

    2016-10-01

    We consider, both theoretically and experimentally, a thin sessile drop of conductive liquid that rests on the lower plate of a parallel-plate capacitor. We derive analytical expressions for both the initial deformation and the relaxation dynamics of the drop as the electric field is either abruptly applied or abruptly removed, as functions of the geometrical, electrical, and material parameters, and investigate the ranges of validity of these expressions by comparison with full numerical simulations. These expressions provide a reasonable description of the experimentally measured dynamic response of a drop of conductive ionic liquid 1-butyl-3-methyl imidazolium tetrafluoroborate.

  12. Dynamic response of a thin sessile drop of conductive liquid to an abruptly applied or removed electric field

    NASA Astrophysics Data System (ADS)

    Corson, L. T.; Mottram, N. J.; Duffy, B. R.; Wilson, S. K.; Tsakonas, C.; Brown, C. V.

    2016-10-01

    We consider, both theoretically and experimentally, a thin sessile drop of conductive liquid that rests on the lower plate of a parallel-plate capacitor. We derive analytical expressions for both the initial deformation and the relaxation dynamics of the drop as the electric field is either abruptly applied or abruptly removed, as functions of the geometrical, electrical, and material parameters, and investigate the ranges of validity of these expressions by comparison with full numerical simulations. These expressions provide a reasonable description of the experimentally measured dynamic response of a drop of conductive ionic liquid 1-butyl-3-methyl imidazolium tetrafluoroborate.

  13. Nonlinear absorption in ionic liquids with transition metallic atoms in the anion

    NASA Astrophysics Data System (ADS)

    Nóvoa-López, José A.; López Lago, Elena; Seijas, Julio A.; Pilar Vázquez-Tato, M.; Troncoso, Jacobo; de la Fuente, Raúl; Salgueiro, José R.; Michinel, Humberto

    2016-02-01

    Nonlinear absorption has been investigated by open aperture Z-scan in ionic liquids obtained by combination of 1-butyl-3-methyl-imidazolium cations with anions containing a transition metal (Co, Zn, Cu or Ni) and thiocyanate groups. The laser source was a Ti:Sapphire oscillator (80-fs pulses, λ = 810 nm, repetition rate of 80.75 MHz). All liquids present quite low heat capacities that favor the development of strong thermal effects. Thermal effects and nonlinear absorption make them potential materials for optical limiting purposes.

  14. Accelerated CO2 transport on surface of AgO nanoparticles in ionic liquid BMIMBF4

    NASA Astrophysics Data System (ADS)

    Ji, Dahye; Kang, Yong Soo; Kang, Sang Wook

    2015-11-01

    The AgO nanoparticles were utilized for a CO2 separation membrane. The AgO nanoparticles were successfully generated in ionic liquid 1-butyl-3-methyl imidazolium tetrafluoroborate (BMIMBF4) by favorable interaction between the surface of particles and the counteranion of BMIMBF4. The generated AgO nanoparticles were confirmed by TEM, and the average size was 20 nm. Coordinative interactions of dissociated AgO particles with BMIM+BF4- were investigated by FT-Raman spectroscopy. When the ionic liquid BMIMBF4 containing AgO nanoparticles was utilized as a CO2 separation membrane, the separation performance was largely enhanced.

  15. Accelerated CO2 transport on surface of AgO nanoparticles in ionic liquid BMIMBF4

    PubMed Central

    Ji, Dahye; Kang, Yong Soo; Kang, Sang Wook

    2015-01-01

    The AgO nanoparticles were utilized for a CO2 separation membrane. The AgO nanoparticles were successfully generated in ionic liquid 1-butyl-3-methyl imidazolium tetrafluoroborate (BMIMBF4) by favorable interaction between the surface of particles and the counteranion of BMIMBF4. The generated AgO nanoparticles were confirmed by TEM, and the average size was 20 nm. Coordinative interactions of dissociated AgO particles with BMIM+BF4− were investigated by FT-Raman spectroscopy. When the ionic liquid BMIMBF4 containing AgO nanoparticles was utilized as a CO2 separation membrane, the separation performance was largely enhanced. PMID:26549605

  16. New Insights Into the Role of Imidazolium-Based Promoters for the Electroreduction of CO2 on a Silver Electrode.

    PubMed

    Lau, Genevieve P S; Schreier, Marcel; Vasilyev, Dmitry; Scopelliti, Rosario; Grätzel, Michael; Dyson, Paul J

    2016-06-29

    The electrochemical reduction of CO2 to CO is a reaction of central importance for sustainable energy conversion and storage. Herein, structure-activity relationships of a series of imidazolium-based cocatalysts for this reaction are described, which demonstrate that the C4- and C5-protons on the imidazolium ring are vital for efficient catalysis. Further investigation of these findings led to the discovery of new imidazolium salts, which show superior activity as cocatalysts for the reaction, i.e., CO is selectively produced at significantly lower overpotentials with nearly quantitative faradaic yields for CO.

  17. Effects of substituents and substitution positions on alkaline stability of imidazolium cations and their corresponding anion-exchange membranes.

    PubMed

    Si, Zhihong; Qiu, Lihua; Dong, Huilong; Gu, Fenglou; Li, Youyong; Yan, Feng

    2014-03-26

    Imidazolium cations with butyl groups at various substitution positions (N1-, C2-, and N3-), 1-butyl-2,3-dimethylimidazolium ([N1-BDMIm](+)), 2-butyl-1,3-dimethylimidazolium ([C2-BDMIm](+)), and 3-butyl-1,2-dimethylimidazolium ([N3-BDMIm](+)), were synthesized. Quantitative (1)H NMR spectra and density functional theory calculation were applied to investigate the chemical stability of the imidazolium cations in alkaline solutions. The results suggested that the alkaline stability of the imidazolium cations was drastically affected by the C2-substitution groups. The alkaline stability of imidazolium cations with various substitution groups at the C2-position, including 2-ethyl-1-butyl-3-methylimidazolium ([C2-EBMIm](+)), 1,2-dibutyl-3-methylimidazolium ([C2-BBMIm](+)), and 2-hydroxymethyl-1-butyl-3-methylimidazolium ([C2-HMBMIm](+)), was further studied. The butyl group substituted imidazolium cation ([C2-BBMIm](+)) exhibited the highest alkaline stability at the elevated temperatures. The synthesized anion-exchange membranes based on the [C2-BBMIm](+) cation showed promising alkaline stability. These observations should pave the way to the practical application of imidazolium-based anion exchange membrane fuel cells.

  18. Identification of Structural Motifs of Imidazolium Based Ionic Liquids from Jet-Cooled Infrared Spectroscopy.

    NASA Astrophysics Data System (ADS)

    Young, Justin W.; Booth, Ryan S.; Annesley, Christopher; Stearns, Jaime A.

    2016-06-01

    Highly variable and potentially revolutionary, ionic liquids (IL) are a class of molecules with potential for numerous Air Force applications such as satellite propulsion, but the complex nature of IL structure and intermolecular interactions makes it difficult to adequately predict structure-property relationships in order to make new IL-based technology a reality. For example, methylation of imidazolium ionic liquids leads to a substantial increase in viscosity but the underlying physical mechanism is not understood. In addition the role of hydrogen bonding in ILs, especially its relationship to macroscopic properties, is a matter of ongoing research. Here, structural motifs are identified from jet-cooled infrared spectra of different imidazolium based ionic liquids, such as 1-ethyl-3-methylimidazolium bis(trifluoromethyl-sulfonyl)imide. Measurements of the C-H stretches indicate three structural families present in the gas phase.

  19. 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.

  20. Infrared and Ultraviolet Spectroscopy of Gas-Phase Imidazolium and Pyridinium Ionic Liquids.

    NASA Astrophysics Data System (ADS)

    Young, Justin W.; Booth, Ryan S.; Annesley, Christopher; Stearns, Jaime A.

    2015-06-01

    Ionic liquids (ILs) are a highly variable and potentially game-changing class of molecules for a number of Air Force applications such as satellite propulsion, but the complex nature of IL structure and intermolecular interactions makes it difficult to adequately predict structure-property relationships in order to make new IL-based technology a reality. For example, methylation of imidazolium ionic liquids leads to a substantial increase in viscosity but the underlying physical mechanism is not understood. In addition, the role of hydrogen bonding in ILs, and especially its relationship to macroscopic properties, is a matter of ongoing research. Here we describe the gas-phase spectroscopy of a series of imidazolium- and pyridinium-based ILs, using a combination of infrared spectroscopy and density functional theory to establish the intermolecular interactions present in various ILs, to assess how well they are described by theory, and to relate microscopic structure to macroscopic properties.

  1. Electrospray mass spectral fragmentation study of N,N'-disubstituted imidazolium ionic liquids.

    PubMed

    Lesimple, Alain; Mamer, Orval; Miao, Weishi; Chan, Tak Hang

    2006-01-01

    The tandem positive electrospray mass spectrometry (ESMS(n)) fragmentation of ionic liquids incorporating the 1-methyl-imidazolium ring substituted on N(II) with an alkyl chain functionalized with an alcohol, carboxylic acid, or an iodobenzyl or iodobenzoyl ester is presented for the first time. The influence of chain length and function is studied. Esterified structures led to intense CID fragments lacking the imidazolium ring allowing full characterization of the ester moiety. Fragment ion compositions for this interesting and newly important class of compounds are established through accurate mass data and deuterium labeling. The presence of the cationic ring system produces intense even electron molecular cations in electrospray that undergo multiple stages of CID to yield fragments which often are radical cations. Unusual losses of methyl and hydrogen radicals are frequently noted.

  2. Multitask Imidazolium Salt Additives for Innovative Poly(l-lactide) Biomaterials: Morphology Control, Candida spp. Biofilm Inhibition, Human Mesenchymal Stem Cell Biocompatibility, and Skin Tolerance.

    PubMed

    Schrekker, Clarissa M L; Sokolovicz, Yuri C A; Raucci, Maria G; Selukar, Balaji S; Klitzke, Joice S; Lopes, William; Leal, Claudio A M; de Souza, Igor O P; Galland, Griselda B; Dos Santos, João Henrique Z; Mauler, Raquel S; Kol, Moshe; Dagorne, Samuel; Ambrosio, Luigi; Teixeira, Mário L; Morais, Jonder; Landers, Richard; Fuentefria, Alexandre M; Schrekker, Henri S

    2016-08-24

    Candida species have great ability to colonize and form biofilms on medical devices, causing infections in human hosts. In this study, poly(l-lactide) films with different imidazolium salt (1-n-hexadecyl-3-methylimidazolium chloride (C16MImCl) and 1-n-hexadecyl-3-methylimidazolium methanesulfonate (C16MImMeS)) contents were prepared, using the solvent casting process. Poly(l-lactide)-imidazolium salt films were obtained with different surface morphologies (spherical and directional), and the presence of the imidazolium salt in the surface was confirmed. These films with different concentrations of the imidazolium salts C16MImCl and C16MImMeS presented antibiofilm activity against isolates of Candida tropicalis, Candida parapsilosis, and Candida albicans. The minor antibiofilm concentration assay enabled one to determine that an increasing imidazolium salt content promoted, in general, an increase in the inhibition percentage of biofilm formation. Scanning electron microscopy micrographs confirmed the effective prevention of biofilm formation on the imidazolium salt containing biomaterials. Lower concentrations of the imidazolium salts showed no cytotoxicity, and the poly(l-lactide)-imidazolium salt films presented good cell adhesion and proliferation percentages with human mesenchymal stem cells. Furthermore, no acute microscopic lesions were identified in the histopathological evaluation after contact between the films and pig ear skin. In combination with the good morphological, physicochemical, and mechanical properties, these poly(l-lactide)-based materials with imidazolium salt additives can be considered as promising biomaterials for use in the manufacturing of medical devices.

  3. Intramolecular general acid catalysis of the hydrolysis of 2-(2'-imidazolium)phenyl phosphate, and bond length-reactivity correlations for reactions of phosphate monoester monoanions.

    PubMed

    Brandão, Tiago A S; Orth, Elisa S; Rocha, Willian R; Bortoluzzi, Adailton J; Bunton, Clifford A; Nome, Faruk

    2007-05-11

    Rate constants for the hydrolysis of 2-(2'-imidazolium)phenyl hydrogen phosphate (IMPP) in water at pH<6 indicate that activation by the imidazolium moiety disappears with the deprotonation of the phosphate group, and the reaction involves the hydrogen-bonding of the imidazolium NH with the aryl oxygen leaving group. The reaction should involve a near-planar conformation of the imidazolium and the phenyl groups in the activated complex, which favors proton-transfer. The crystal structure of IMPP was solved, and a bond length-reactivity correlation for reactions of phosphate monoester monoanions is described.

  4. Low-frequency Raman spectra and fragility of imidazolium ionic liquids.

    PubMed

    Ribeiro, Mauro C C

    2010-07-14

    Raman spectra within the 5-200 cm(-1) range have been recorded as a function of temperature for different ionic liquids based on imidazolium cations. A correlation has been found between fragility and the temperature dependence of the strength of fast relaxational motions. Understanding quasielastic scattering as the relaxational contribution to ionic mean-squared displacement elucidates some effects on ionic liquids' fragility resulting from modifications in the chemical structure.

  5. Novel use of imidazolium ylides in an efficient synthesis of 2-substituted imidazoles.

    PubMed

    Hlasta, D J

    2001-01-25

    [figure: see text] A new reaction of imidazoles was discovered involving the formation of an imidazolium ylide, which on trapping with various electrophiles afforded diverse 2-substituted imidazoles. The facile, convenient reaction conditions when compared to the existing procedures make this reaction the method of choice in the preparation of 2-substituted imidazoles. Moreover, the reaction differs from the reported methods since the products (viz., 1) contain an alpha-substituent that is transformed by solvolysis chemistry into further functionalized derivatives.

  6. Nature of the C2-methylation effect on the properties of imidazolium ionic liquids.

    PubMed

    Rodrigues, Ana S M C; Lima, Carlos F R A C; Coutinho, João A P; Santos, Luís M N B F

    2017-02-15

    Methylation at the C2 position of 1,3-disubstituted imidazolium-based ionic liquids (ILs) is one of the structural features that has gained attention due to its drastic impact on thermophysical and transport properties. Several hypotheses have been proposed to explain this effect but there is still much discrepancy. Aiming for the rationalization of the effects of these structural features on the properties of imidazolium ILs, we present a thermodynamic and computational study of two methylated ILs at the C2 position of imidazolium, [(1)C4(2)C1(3)C1im][NTf2] and [(1)C3(2)C1(3)C1im][NTf2]. The phase behaviour (glass transition and vaporization equilibrium) and computational studies of the anion rotation around the cation and ion pair interaction energies for both ILs were explored. The results have shown that C2-methylation has no impact on the enthalpy of vaporization. However, it decreases the entropy of vaporization, which is a consequence of the change in the ion pair dynamics that affects both the liquid and gas phases. In addition, the more hindered dynamics of the ion pair are also reflected in the increase in the glass transition temperature, Tg. The entropic contribution of anion-around-cation rotation in the imidazolium [NTf2] ILs was quantified experimentally by the comparative analysis of the entropy of vaporization, and computationally by the calculation of the entropies of hindered internal rotation. The global results exclude the existence of significant H-bonding in the C2-protonated (non-methylated) ILs and explain the C2-methylation effect in terms of reduced entropy of the ion pair in the liquid and gas phases. In light of these results, the C2-methylation effect is intrinsically entropic and originates from the more hindered anion-around-cation rotation as a consequence of the substitution of the -H with a bulkier -CH3 group.

  7. Equimolar CO(2) capture by imidazolium-based ionic liquids and superbase systems

    SciTech Connect

    Dai, Sheng; Wang, Chongmin; Luo, Huimin; Luo, Xiaoyan; Li, Qing; Li, Haoran

    2010-01-01

    Imidazolium-based ionic liquids continue to attract interest in many areas of chemistry because of their low melting points, relatively low viscosities, ease of synthesis, and good stabilities against oxidative and reductive conditions. However, they are not totally inert under many conditions due to the intrinsic acidity of hydrogen at the C-2 position in the imidazolium cation. In this work, this intrinsic acidity was exploited in combination with an organic superbase for the capture of CO{sub 2} under atmospheric pressure. During the absorption of CO{sub 2}, the imidazolium-based ionic liquid containing an equimolar superbase reacted with CO{sub 2} to form a liquid carboxylate salt so that the equimolar capture of CO{sub 2} with respect to the base was achieved. The effects of ionic liquid structures, types of organic superbases, absorption times, and reaction temperatures on the capture of CO{sub 2} were investigated. Our results show that this integrated ionic liquid-superbase system is capable of rapid and reversible capture of about 1 mol CO{sub 2} per mole of ionic liquid. Furthermore, the captured CO{sub 2} can be readily released by either heating or bubbling N{sub 2}, and recycled with little loss of its capture capability. This efficient and reversible catch-and-release process using the weak acidity of the C-2 proton in nonvolatile imidazolium-based ionic liquids provides a good alternative to the current CO{sub 2} capture methods that use volatile alkanols, amines, or water.

  8. Exploiting the Imidazolium Effect in Base-free Ammonium Enolate Generation: Synthetic and Mechanistic Studies.

    PubMed

    Young, Claire M; Stark, Daniel G; West, Thomas H; Taylor, James E; Smith, Andrew D

    2016-11-07

    N-Acyl imidazoles and catalytic isothiourea hydrochloride salts function as ammonium enolate precursors in the absence of base. Enantioselective Michael addition-cyclization reactions using different α,β-unsaturated Michael acceptors have been performed to form dihydropyranones and dihydropyridinones with high stereoselectivity. Detailed mechanistic studies using RPKA have revealed the importance of the "imidazolium" effect in ammonium enolate formation and have highlighted key differences with traditional base-mediated processes.

  9. Low-frequency Raman spectra and fragility of imidazolium ionic liquids

    SciTech Connect

    Ribeiro, Mauro C. C.

    2010-07-14

    Raman spectra within the 5-200 cm{sup -1} range have been recorded as a function of temperature for different ionic liquids based on imidazolium cations. A correlation has been found between fragility and the temperature dependence of the strength of fast relaxational motions. Understanding quasielastic scattering as the relaxational contribution to ionic mean-squared displacement elucidates some effects on ionic liquids' fragility resulting from modifications in the chemical structure.

  10. Therapeutic effect of a multi-targeted imidazolium compound in hepatocellular carcinoma.

    PubMed

    Gopalan, Began; Narayanan, Karthikeyan; Ke, Zhiyuan; Lu, Ting; Zhang, Yugen; Zhuo, Lang

    2014-08-01

    Hepatocellular carcinoma (HCC) is one of the most commonly diagnosed lethal cancers in the world. We previously showed two imidazolium salts (IBN-1 and IBN-9) with a moderate efficacy for HCC. Here we report a more potent imidazolium compound IBN-65 (1-benzyl-2-phenyl-3-(4-isopropyl)-benzyl-imidazolium chloride) and the associated mechanisms of action in a mouse model of HCC. The IC50 of this compound in various liver cancer cell lines was around 5 μm. IBN-65 dose-dependently arrested cell cycle at G1 phase and was associated with the down-regulation of the cyclin-dependent kinase-4, -6, cyclin D1, and cyclin E. In addition, IBN-65 induced apoptosis by down-regulating Survivin, Bcl-2 and up-regulating Bax, leading to sequential activation of Caspase-3, Caspase-9 and the cleavage of poly(ADP-ribose) polymerase (PARP). Dysregulation of the epidermal growth factor receptor (EGFR) signaling network has been frequently reported in HCC. We found that IBN-65 displayed a profound inhibitory effect on the EGFR/Raf/MEK/ERK signaling at the phosphorylation level. In Huh7 or Hep3B cells, pretreatment with IBN-65 attenuated EGF-induced phosphorylation of both EGFR and the downstream p44/42 MAPK. A siRNA knockdown of EGFR also proved that IBN-65 induced apoptosis mostly through inhibiting downstream EGFR pathway signaling, much less at the receptor level. Infrequent administration of IBN-65 (i.p., 5 mg/kg once weekly for four weeks) to mice bearing the Huh7 cells significantly reduced the tumor volume by 65% without affecting the body weight. Critically, many of the anti-tumor signaling features observed in the HCC cell lines were recaptured in the xenografted tissues. Thus, the metal-free imidazolium compound IBN-65 could be a potential candidate towards therapeutic development for HCC.

  11. Carbon dioxide capture by aminoalkyl imidazolium-based ionic liquid: a computational investigation.

    PubMed

    Chen, Jie-Jie; Li, Wen-Wei; Li, Xue-Liang; Yu, Han-Qing

    2012-04-07

    Efficient technologies/processes for CO(2) capture are greatly desired, and ionic liquids are recognized as promising materials for this purpose. However, the mechanisms for selectively capturing CO(2) by ionic liquids are unclear. In this study, the interactions between CO(2) and 1-n-amino-alkyl-3-methyl-imidazolium tetrafluoroborate, an amino imidazolium ionic liquid (AIIL), in its CO(2) capturing process, are elucidated with both quantum chemistry and molecular dynamics approaches on the molecular level. The effects of the straight aminoalkyl chain length in imidazolium-based cations on CO(2) capture are explored, and thereby the factors governing CO(2) capture for this ionic liquid family, e.g., ionic liquid structure, charge distribution, intermolecular interactions, thermodynamic properties and absorption kinetics, are analyzed. Molecular dynamics simulations are used to study the diffusion of the involved compounds and liquid structures of the CO(2)-AIIL systems. The results show that the amino-alkyl chain length plays an important role in governing the absorption properties of AIILs, including the free energies of absorption, equilibrium constants, desorption temperature, absorption rate constants, diffusion coefficients, and organization of CO(2) around cations and anions. This study provides useful information about rational design of ionic liquids for efficient CO(2) capture.

  12. Thermal properties and ionic conductivity of imidazolium bis(trifluoromethanesulfonyl)imide dicationic ionic liquids.

    PubMed

    Pitawala, Jagath; Matic, Aleksandar; Martinelli, Anna; Jacobsson, Per; Koch, Victor; Croce, Fausto

    2009-08-06

    We report on the thermal and transport properties of new dicationic ionic liquids. The new ionic liquids are based on the bis(trifluoromethanesulfonyl)imide [NTf(2)](-) anion and a cation that contains two imidazolium rings, connected by either a pentane or a decane hydrocarbon chain and different side groups. We have investigated the conductivity and the thermal properties by dielectric spectroscopy and differential scanning calorimetry, respectively. Our results show that the length of the alkyl chain on the cation has no, or weak, influence on the glass transition temperature, T(g), whereas the presence of rigid aromatic side groups has a strong influence increase T(g). The highest ionic conductivity is 5.9 x 10(-4) S cm(-1) at 298 K for an ionic liquid with a decane chain and one methyl group on each imidazolium ring. The conductivity results correlate well with the glass transition temperatures. This shows that the flexibility of the geminal cations is very important for the conductivity. However, the presence of nonflexible aromatic side groups on the imidazolium ring decreases the flexibility and hence the mobility.

  13. A Highly Reactive Imidazolium-Bridged Dinucleotide Intermediate in Nonenzymatic RNA Primer Extension.

    PubMed

    Walton, Travis; Szostak, Jack W

    2016-09-14

    Because of its importance for the origin of life, the nonenzymatic copying of RNA templates has been the subject of intense study for several decades. Previous characterizations of template-directed primer extension using 5'-phosphoryl-2-methylimidazole-activated nucleotides (2-MeImpNs) as substrates have assumed a classical in-line nucleophilic substitution mechanism, in which the 3'-hydroxyl of the primer attacks the phosphate of the incoming monomer, displacing the 2-methylimidazole leaving group. However, we have found that the initial rate of primer extension depends on the pH and concentration at which the activated monomer is maintained prior to the primer extension reaction. These and other results suggest an alternative mechanism, in which two monomers react with each other to form an imidazolium-bridged dinucleotide intermediate, which then binds to the template. Subsequent attack of the 3'-hydroxyl of the primer displaces an activated nucleotide as the leaving group and results in extension of the primer by one nucleotide. Analysis of monomer solutions by NMR indicates formation of the proposed imidazolium-bridged dinucleotide in the expected pH-dependent manner. We have used synthetic methods to prepare material that is enriched in this proposed intermediate and show that it is a highly reactive substrate for primer extension. The formation of an imidazolium-bridged dinucleotide intermediate provides a mechanistic interpretation of previously observed catalysis by an activated nucleotide located downstream from the site of primer extension.

  14. An internal fluorescent probe based on anthracene to evaluate cation-anion interactions in imidazolium salts.

    PubMed

    Fei, Zhaofu; Zhu, Dun-Ru; Yang, Xue; Meng, Lingjie; Lu, Qinghua; Ang, Wee Han; Scopelliti, Rosario; Hartinger, Christian G; Dyson, Paul J

    2010-06-11

    A series of fluorescent imidazolium-based salts containing the cation [AnCH(2)MeIm](+) (in which An = anthracene and Im = the imidazolium cation) with Cl(-), BF(4)(-), PF(6)(-), SO(3)CF(3)(-), [N(CN)(2)](-), [N(SO(2)CF(3))(2)](-), or PhBF(3)(-) anions have been prepared and characterized. X-ray diffraction analysis of four of the salts reveals a number of C-H...X-type (X = O, N, F) hydrogen bonds between the hydrogen atoms from the imidazolium ring and in some cases from the anthracene ring with the electronegative atoms of the anions. Additionally, C-H...pi interactions can be found in all the salts analyzed by X-ray diffraction, whereas pi-pi stacking is observed only in the salt containing the phenyltrifluoroborate anion. Fluorescence emission analysis in acetonitrile shows that the fluorescence of these salts varies significantly according to the nature of the anion, and correlates to the extent of ion pairing present in solution. Photodimerization of these salts was observed, and in one case a dimer has been isolated and characterized by X-ray crystallography.

  15. Synthesis of Water-Soluble Imidazolium Polyesters as Potential Nonviral Gene Delivery Vehicles.

    PubMed

    Nelson, Ashley M; Pekkanen, Allison M; Forsythe, Neil L; Herlihy, John H; Zhang, Musan; Long, Timothy E

    2017-01-09

    The inherent hydrolytic reactivity of polyesters renders them excellent candidates for a variety of biomedical applications. Incorporating ionic groups further expands their potential impact, encompassing charge-dependent function such as deoxyribonucleic acid (DNA) binding, antibacterial properties, and pH-responsiveness. Catalyst-free and solvent-free polycondensation of a bromomethyl imidazolium-containing (BrMeIm) diol with neopentylglycol (NPG) and adipic acid (AA) afforded novel charged copolyesters with pendant imidazolium sites. Varying ionic content influenced thermal properties and offered a wide-range, -41 to 40 °C, of composition-dependent glass transition temperatures (Tgs). In addition to desirable melt and thermal stability, polyesters with ionic concentrations ≥15 mol % readily dispersed in water, suggesting potential as nonviral gene delivery vectors. An electrophoretic gel shift assay confirmed the novel cationic copolyesters successfully bound DNA at an N/P ratio of 4 for 50 mol % and 75 mol % charged copolyesters (P(NA50-co-ImA50) and P(NA25-co-ImA75)), and an N/P ratio of 5 for 100 mol % Im (PImA). Polyplexes exhibited insignificant cytotoxicity even at high concentrations (200 μg/mL), and a Luciferase transfection assay revealed the ionic (co)polyesters transfected DNA significantly better than the untreated controls. The successful transfection of these novel (co)polyesters inspires future imidazolium-containing polyester design.

  16. Evaluations of imidazolium ionic liquids as novel skin permeation enhancers for drug transdermal delivery.

    PubMed

    Zhang, Ding; Wang, Huai-Ji; Cui, Xiu-Ming; Wang, Cheng-Xiao

    2016-01-13

    In this work, imidazolium ionic liquids (imidazolium ILs) were employed as the novel chemical permeation enhancers (CPEs) and their performances and mechanisms of action were deeply investigated. Testosterone was used as a model drug to investigate the transdermal delivery enhancement of twenty imdidazolium ILs. The results suggested that the promotion activity connected to the structure and composition of the ILs. The quantitative structure-activity relationship (QSAR) model revealed a good linearity between the electronic properties of ILs and their enhancements. Furthermore, the transepidermal water loss (TEWL) and scanning laser confocal microscope (CLSM) examinations showed the strong improvement of ILs on skin barrier permeability, which were well correlated with the drug penetration profiles. The total reflection-Fourier transform infrared spectroscopy (ATR-FTIR) and atomic force microscope (AFM) evaluations of skins indicated that the ILs can disrupt the regular and compact arrangements of the corneocytes, change the surface properties of stratum corneum, and make the skin structure more permeable. Our work demonstrated the significant skin permeation promotion profiles of the imidazolium ILs, which are of great potential in transdermal drug delivery systems.

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

    NASA Astrophysics Data System (ADS)

    Feng, Haijun; Zhou, Jian; Qian, Yu

    2011-10-01

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

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

    EPA Science Inventory

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

  19. A general halide-to-anion switch for imidazolium-based ionic liquids and oligocationic systems using anion exchange resins (A- form).

    PubMed

    Alcalde, Ermitas; Dinarès, Immaculada; Ibáñez, Anna; Mesquida, Neus

    2011-03-21

    Further studies on the application of an AER (A(-) form) method broadened the anion exchange scope of representative ionic liquids and bis(imidazolium) systems. Depending on the hydrophobicity nature of the targeted imidazolium species and counteranions, different organic solvents were used to swap halides for assorted anions, proceeding in excellent to quantitative yields.

  20. Locker Room Talk.

    ERIC Educational Resources Information Center

    Fickes, Michael

    1999-01-01

    Examines the trends in college and university sports and recreation center locker rooms as envisioned by a specialist. Features of the modern locker room and the different levels of locker room design are explained. Final comments discuss whether college and university facility managers are inclined to move to high-end locker rooms. (GR)

  1. In situ observation of multiple phase transitions in low-melting ionic liquid [BMIM][BF4] under high pressure up to 30 GPa.

    PubMed

    Su, Lei; Zhu, Xiang; Wang, Zheng; Cheng, Xuerui; Wang, Yongqiang; Yuan, Chaosheng; Chen, Zhenping; Ma, Chunli; Li, Fangfei; Zhou, Qiang; Cui, Qiliang

    2012-02-23

    In situ characterization of phase transitions and direct microscopic observations of a low-melting ionic liquid, 1-butyl-3-methyl imidazolium tetrafluoroborate ([BMIM][BF(4)]), has been performed in detail by Raman spectroscopy. Compression of [BMIM][BF(4)] was measured under hydrostatic pressure up to ~30.0 GPa at room temperature by using a high-pressure diamond anvil cell. With pressure increasing, the characteristic bands of [BMIM][BF(4)] displayed nonmonotonic pressure-induced frequency shifts, and it is found to undergo four successive phase transitions at around 2.25, 6.10, 14.00, and 21.26 GPa. Especially, above a pressure of 21.26 GPa, luminescence of the sample occurs, which is connected with the most significant phase transition at around this pressure. It was indicated that the structure change under high pressure might be associated with a conformational change in the butyl chain. Upon releasing pressure, the spectrum was not recovered under a pressure up to 1.16 GPa, thereby indicating that this high-pressure phase remains stable over a large pressure range between 30 and 1.16 GPa in low-melting ionic liquid [BMIM][BF(4)]. Although the sample was kept under the normal pressure for 24 h, the spectrum was recovered, and it showed that the phase transition of [BMIM][BF(4)] was reversible. In other words, such a low-melting ionic liquid [BMIM][BF(4)] remains stable even after being treated under so a high pressure of up to 30 GPa. © 2012 American Chemical Society

  2. An imidazolium based ionic liquid electrolyte for lithium batteries

    NASA Astrophysics Data System (ADS)

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

    An electrolyte for lithium batteries based on the ionic liquid 3-methy-1-propylimidazolium bis(trifluoromethysulfony)imide (PMIMTFSI) complexed with lithium bis(trifluoromethysulfony)imide (LiTFSI) at a molar ratio of 1:1 has been investigated. The electrolyte shows a high ionic conductivity (∼1.2 × 10 -3 S cm -1) at room temperature. Over the whole investigated temperature range the ionic conductivity is more than one order of magnitude higher than for an analogue electrolyte based on N-butyl-N-methyl-pyrrolidinium bis(trifluoromethanesulfonyl)imide (Py 14TFSI) complexed with LiTFSI and used here as a benchmark. Raman results indicate furthermore that the degree of lithium coordinated TFSI is slightly lower in the electrolyte based on PMIMTFSI and thus that the Li + charge carriers should be higher than in electrolytes based on Py 14TFSI. An ionic liquid gel electrolyte membrane was obtained by soaking a fibrous fully interconnected membrane, made of electrospun P(VdF-HFP), in the electrolyte. The gel electrolyte was cycled in Li/ionic liquid polymer electrolyte/Li cells over 15 days and in Li/LiFePO 4 cells demonstrating good interfacial stability and highly stable discharge capacities with a retention of >96% after 50 cycles (∼146 mAh g -1).

  3. Crystal structure of the tetra-gonal polymorph of bis-(1-ethyl-3-methyl-imidazolium) tetra-bromido-cadmate.

    PubMed

    Đorđević, Tamara; Gerger, Sabrina; Karanović, Ljiljana

    2016-07-01

    Both unique Cd atoms in the tetra-gonal polymorph of bis-(1-ethyl-3-methyl-imidazolium) tetra-bromido-cadmate, (C6H11N2)2[CdBr4], occupy special positions (site symmetry -4). The crystal structure consists of isolated tetra-hedral [CdBr4](2-) anions which are surrounded by 1-ethyl-3-methyl-imidazolium cations. The methyl and ethyl side chains of the cations show positional disorder in a 0.590 (11):0.410 (11) ratio. In the crystal, (C6H11N2)(+) cations display three weak C-H⋯Br hydrogen-bond inter-actions through the imidazolium ring H atoms with the Br(-) ligands of the surrounding complex anions. The alkyl groups of the side chains are not involved in hydrogen bonding.

  4. Synthesis and characterization of a helicene-based imidazolium salt and its application in organic molecular electronics.

    PubMed

    Storch, Jan; Zadny, Jaroslav; Strasak, Tomas; Kubala, Martin; Sykora, Jan; Dusek, Michal; Cirkva, Vladimir; Matejka, Pavel; Krbal, Milos; Vacek, Jan

    2015-02-02

    Herein we demonstrate the synthesis of a helicene-based imidazolium salt. The salt was prepared by starting from racemic 2-methyl[6]helicene, which undergoes radical bromination to yield 2-(bromomethyl)[6]helicene. Subsequent treatment with 1-butylimidazole leads to the corresponding salt 1-butyl-3-(2-methyl[6]helicenyl)-imidazolium bromide. The prepared salt was subsequently characterized by using NMR spectroscopy and X-ray analysis, various optical spectrometric techniques, and computational chemistry tools. Finally, the imidazolium salt was immobilized onto a SiO2 substrate as a crystalline or amorphous deposit. The deposited layers were used for the development of organic molecular semiconductor devices and the construction of a fully reversible humidity sensor.

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

    SciTech Connect

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

    2013-01-01

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

  6. Enantioselective toxicities of chiral ionic liquids 1-alkyl-3-methyl imidazolium tartrate on Scenedesmus obliquus.

    PubMed

    Liu, Huijun; Zhang, Xiaoqiang; Dong, Ying; Chen, Caidong; Zhu, Shimin; Ma, Xiangjuan

    2015-12-01

    Ionic liquids (ILs) are being used in various industries during the last few decades, while the good solubility and high stability of ILs may pose a potential threat to the aquatic environment. Effect of chiral ionic liquids (CILs) 1-alkyl-3-methyl imidazolium tartrate (RMIM T) on Scenedesmus obliquus (S.obliquus) was studied. The growth rate inhibition and cell membrane permeability increased with increasing RMIM T concentration and increasing alkyl chain lengths. The IC50 values of D-(-)-tartrate 1-hexyl-3-methyl imidazolium (D-(-)-HMIM T) were 28.30, 12.23,10.15 and 14.41 mg/L, respectively, at 24, 48, 72 and 96h. While that of L-(+)-tartrate 1-hexyl-3-methyl imidazolium (L-(+)-HMIM T) were 15.97, 7.91, 9.43 and 12.04 mg/L respectively. The concentration of chl a, chl b and chl (a+b) decreased with increasing RMIM T concentration. The chlorophyll fluorescence parameters (F0, Fv/Fm, Fv/F0, Y(II), ETR and NPQ) were affected by RMIM T, indicating that the RMIM T will damage the PSII, inhibit the transmission of excitation energy, decrease the efficiency of photosynthesis. The results showed that there were enantioselective toxicity of RMIM T to algae, and the toxicity of L-(+)-RMIM T was greater than that of D-(-)-RMIM T, but the enantioselective difference becomes smaller with increasing exposure time, and with the increasing carbon chain length of cation, indicating that cation properties may have a larger effect on toxicity than anion properties. Copyright © 2015 Elsevier B.V. All rights reserved.

  7. Thermal Stability Limits of Imidazolium Ionic Liquids Immobilized on Metal-Oxides.

    PubMed

    Babucci, Melike; Akçay, Aslı; Balci, Volkan; Uzun, Alper

    2015-08-25

    Thermal stability limits of 33 imidazolium ionic liquids (ILs) immobilized on three of the most commonly used high surface area metal-oxides, SiO2, γ-Al2O3, and MgO, were investigated. ILs were chosen from a family of 13 cations and 18 anions. Results show that the acidity of C2H of an imidazolium ring is one of the key factors controlling the thermal stability. An increase in C2H bonding strength of ILs leads to an increase in their stability limits accompanied by a decrease in interionic energy. Systematic changes in IL structure, such as changes in electronic structure and size of anion/cation, methylation on C2 site, and substitution of alkyl groups on the imidazolium ring with functional groups have significant effects on thermal stability limits. Furthermore, thermal stability limits of ILs are influenced strongly by acidic character of the metal-oxide surface. Generally, as the point of zero charge (PZC) of the metal-oxide increases from SiO2 to MgO, the interactions of IL and metal-oxide dominate over interionic interactions, and metal-oxide becomes the significant factor controlling the stability limits. However, thermal stability limits of some ILs show the opposite trend, as the chemical activities of the cation functional group or the electron donating properties of the anion alter IL/metal-oxide interactions. Results presented here can help in choosing the most suitable ILs for materials involving ILs supported on metal-oxides, such as for supported ionic liquid membranes (SILM) in separation applications or for solid catalyst with ionic liquid layer (SCILL) and supported ionic liquid phase (SILP) catalysts in catalysis.

  8. Selective Activation of Fluoroalkenes with N-Heterocyclic Carbenes: Synthesis of N-Heterocyclic Fluoroalkenes and Polyfluoroalkenyl Imidazolium Salts.

    PubMed

    Leclerc, Matthew C; Gorelsky, Serge I; Gabidullin, Bulat M; Korobkov, Ilia; Baker, R Tom

    2016-06-06

    Selective reactions between nucleophilic N,N'-diaryl-heterocyclic carbenes (NHCs) and electrophilic fluorinated alkenes afford NHC fluoroalkenes in high yields. These stable compounds undergo efficient and selective fluoride abstraction with Lewis acids to give polyfluoroalkenyl imidazolium salts. These salts react at Cβ with pyrrolidine to give ammonium fluoride-substituted salts, which give rise to conjugated imidazolium-enamine salts through loss of HF. Alternatively, reaction with 4-(dimethylamino)-pyridine provides a Cα-pyridinium-substituted NHC fluoroalkene. These compounds were studied using multinuclear NMR spectroscopy, mass spectrometry, and X-ray crystallography. Insight into their electronic structure and reactivity was gained through the use of DFT calculations.

  9. Neighbor-directed Histidine N(τ)–Alkylation: A Route to Imidazolium-containing Phosphopeptide Macrocycles

    PubMed Central

    Qian, Wen-Jian; Park, Jung-Eun; Grant, Robert; Lai, Christopher C.; Kelley, James A.; Yaffe, Michael B.; Lee, Kyung S.; Burke, Terrence R.

    2016-01-01

    Our recently discovered, selective, on-resin route to N(τ)-alkylated imidazolium-containing histidine residues affords new strategies for peptide mimetic design. In our current work, we demonstrate the use of this chemistry to prepare a series of macrocyclic phosphopeptides, in which imidazolium groups serve as ring-forming junctions. Interestingly, these cationic moieties subsequently serve to charge-mask the phosphoamino acid group that directed their formation. Neighbor-directed histidine N(τ)-alkylation opens the door to new families of phosphopeptidomimetics for use in a range of chemical biology contexts. PMID:26152807

  10. Solvent Extraction Separation of La3+ and Ba2+ using Imidazolium Ionic Liquids and TODGA Extractant

    SciTech Connect

    Bell, Jason R; Dai, Sheng; Luo, Huimin

    2012-01-01

    Solvent extractions of La3+ and Ba2+ by N,N,N ,N -tetra(n-octyl)diglycolamide (TODGA) from aqueous solutions in twelve imidazolium-based ionic liquids (ILs), 1-alkyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide / bis(perfluoroethylsulfonyl)imide ([Cnmim][NTf2]/[BETI], n = 2,3, 4, 6, 8, 10) were investigated. The corresponding extraction efficiencies were found to be dependent on concentration of TODGA used, the acidity of aqueous phase, alkyl chain length on IL cation, and IL anion as well.

  11. Nature of hydrogen bonding in charged hydrogen-bonded complexes and imidazolium-based ionic liquids.

    PubMed

    Izgorodina, Ekaterina I; MacFarlane, Douglas R

    2011-12-15

    The nature of hydrogen bonding was compared in neutral complexes and negatively charged complexes consisting of either the HF molecule or the halide anion (fluoride and chloride) and the C-H bond in the methane molecule with a varying degree of fluorination (such as CH(4), CH(2)F(2), and CHF(3)). Both linear (C(3v) symmetry) and nonlinear (C(2v) symmetry) hydrogen-bonded complexes were studied. Symmetry-adapted perturbation theory was used to decompose interaction energies into fundamental components such as Coulomb, repulsion, induction and dispersion to analyze the interplay among these forces in stabilizing hydrogen bonding. In the linear charged complexes, both Coulomb attraction and induction significantly contributed to the stabilization of hydrogen bonding. In the nonlinear charged complexes, mainly Coulomb attraction contributed to the HB complex stabilization, with the inductive forces playing a less important role. Contrary to the neutral complexes, dispersion forces played only a marginal role in the charged complexes. Interplay between the fundamental forces was also investigated in the ion pairs of the imidazolium-based ionic liquid, [C(2)mim]Cl, that were categorized as either (1) typical ion-ion interaction, with the anion interacting from above or below the imidazolium plane; or (2) hydrogen-bonding interaction, with the anion interacting with the C2-H bond of the imidazolium cation. Both types of interactions were found to induce similar charge transfers, and the analysis of the energetic components revealed only a slight difference in the ion pairs studied: (1) both interactions were electrostatically driven, between 86% and 88% of the overall attractive energy, with the electrostatic component being slightly lower in the hydrogen-bonded ion pairs by ~8 kJ mol(-1); and (2) dispersion forces were found to be stronger in the typical ion-ion interactions by ~15 kJ mol(-1) and could be possible only due to the fact that the anion was able to move

  12. Crystal structure of 1-benzyl-3-methyl-1H-imidazolium hexa-fluorido-phosphate.

    PubMed

    Hillesheim, Patrick C; Scipione, Kent A

    2014-12-01

    In the title salt, C11H13N2 (+)·PF6 (-), the dihedral angle between the planes of the imidazole and benzene rings is 84.72 (4)°. In the crystal, C-H⋯F inter-actions connect the cation and anion pairs into a three-dimensional network. Weak π-π inter-actions are observed between the imidazolium ring and the aromatic benzene ring of an adjacent mol-ecule with C⋯C and C⋯N distances ranging from 3.3714 (16) to 3.4389 (15) Å.

  13. 1,3-Bis[(6-methyl-2-pyrid-yl)meth-yl]imidazolium bromide.

    PubMed

    Kim, Ga Young; Park, Sang-Kyu; Lee, Dong-Heon; Park, Gyungse

    2009-02-28

    The title compound, C(17)H(19)N(4) (+)·Br(-), is built up from 1,3-bis-[(6-methyl-2-pyridin-yl)meth-yl]imidazolium cations and bromide anions. Each of two 6-methyl-2-pyridyl rings is rotated out of the imidazole plane, making dihedral angles of 79.90 (9) and 86.40 (9)°. The packing is consolidated by aromatic π-π inter-actions between the pyridine rings of neighbouring mol-ecules [centroid-centroid distance = 3.554 (2) Å] and by weak C-H⋯N and C-H⋯Br hydrogen bonds.

  14. Improving operating room safety

    PubMed Central

    2009-01-01

    Despite the introduction of the Universal Protocol, patient safety in surgery remains a daily challenge in the operating room. This present study describes one community health system's efforts to improve operating room safety through human factors training and ultimately the development of a surgical checklist. Using a combination of formal training, local studies documenting operating room safety issues and peer to peer mentoring we were able to substantially change the culture of our operating room. Our efforts have prepared us for successfully implementing a standardized checklist to improve operating room safety throughout our entire system. Based on these findings we recommend a multimodal approach to improving operating room safety. PMID:19930577

  15. Imidazolium-Based Poly(Ionic Liquid)s Featuring Acetate Counter Anions: Thermally Latent and Recyclable Precursors of Polymer-Supported N-Heterocyclic Carbenes for Organocatalysis.

    PubMed

    Lambert, Romain; Coupillaud, Paul; Wirotius, Anne-Laure; Vignolle, Joan; Taton, Daniel

    2016-07-01

    Statistical copoly(ionic liquid)s (coPILs), namely, poly(styrene)-co-poly(4-vinylbenzylethylimidazolium acetate) are synthesized by free-radical copolymerization in methanolic solution. These coPILs serve to in situ generate polymer-supported N-heterocyclic carbenes (NHCs), referred to as polyNHCs, due to the noninnocent role of the weakly basic acetate counter-anion interacting with the proton in C2-position of pendant imidazolium rings. Formation of polyNHCs is first evidenced through the quantitative formation of NHC-CS2 units by chemical postmodification of acetate-containing coPILs, in the presence of CS2 as electrophilic reagent (= stoichiometric functionalization of polyNHCs). The same coPILs are also employed as masked precursors of polyNHCs in organocatalyzed reactions, including a one-pot two-step sequential reaction involving benzoin condensation followed by addition of methyl acrylate, cyanosilylation, and transesterification reactions. The catalytic activity can be switched on and off successively upon thermal activation, thanks to the deprotonation/reprotonation equilibrium in C2-position. NHC species are thus in situ released upon heating at 80 °C (deprotonation), while regeneration of the coPIL precursor occurs at room temperature (reprotonation), triggering its precipitation in tetrahydrofuran. This also allows recycling the coPIL precatalyst by simple filtration, and reusing it for further catalytic cycles. The different organocatalyzed reactions tested can thus be performed with excellent yields after several cycles.

  16. 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.

  17. Effect of unsaturation on the absorption of ethane and ethylene in imidazolium-based ionic liquids.

    PubMed

    Moura, Leila; Mishra, Manas; Bernales, Varinia; Fuentealba, Patricio; Padua, Agilio A H; Santini, Catherine C; Costa Gomes, Margarida F

    2013-06-20

    The influence of the presence of imidazolium side chain unsaturation on the solubility of ethane and ethylene was studied in three ionic liquids: 1-butyl-3-methylimidazolium bis(trifluoromethanesulfonyl)amide-saturated alkyl side-chain in the cation; 1-methyl-3-(buten-3-yl)imidazolium bis(trifluorosulfonyl)imide-double bond in the side-chain of the cation; and 1-methyl-3-benzylimidazolium bis(trifluorosulfonyl)imide-benzyl group in the side-chain of the cation. The solubility of both gases decreases when the side-chain of the cations is functionalized with an unsaturated group. This can be explained by a less favorable enthalpy of solvation. The difference of solubility between ethane and ethylene can be explained from a balance of enthalpic and entropic factors: for the ionic liquid with the saturated alkyl side-chain and the benzyl-substituted side-chain, it is the favorable entropy of solvation that explains the larger ethylene solubility, whereas in the case of the saturated side-chain, it is the more favorable enthalpy of solvation. Molecular simulation allowed the identification of the mechanisms of solvation and the preferential solvation sites for each gas in the different ionic liquids. Simulations have shown that the entropy of solvation is more favorable when the presence of the gas weakens the cation-anion interactions or when the gas can be solvated near different sites of the ionic liquid.

  18. Influence of oxygen functionalities on the environmental impact of imidazolium based ionic liquids.

    PubMed

    Deng, Yun; Besse-Hoggan, Pascale; Sancelme, Martine; Delort, Anne-Marie; Husson, Pascale; Gomes, Margarida F Costa

    2011-12-30

    Several physico-chemical properties relevant to determine the environmental impact of ionic liquids - aqueous solubility, octanol-water partition coefficient and diffusion coefficients in water at infinite dilution - together with toxicity and biodegradability of ionic liquids based on 1-alkyl-3-methylimidazolium cations with or without different oxygenated functional groups (hydroxyl, ester and ether) are studied in this work. The presence of oxygen groups on the imidazolium cation reduces the toxicity of ionic liquids 1-alkyl-3-methylimidazolium with bis(trifluoromethylsulfonyl)imide or octylsulfate anions and simultaneously decreases the value of their octanol-water partition coefficient. The presence of ester functions renders the ionic liquids more easily biodegradable, especially for long alkyl side-chains in the cation but leads to hydrolysis with the formation of reaction products that accumulate. The imidazolium ring is resistant to biodegradability and to abiotic degradation. The oxygen functionalised ionic liquids are more soluble in water and, diffuse more slowly in this medium. Copyright © 2011 Elsevier B.V. All rights reserved.

  19. High viscosity of imidazolium ionic liquids with the hydrogen sulfate anion: a Raman spectroscopy study.

    PubMed

    Ribeiro, Mauro C C

    2012-06-21

    Ionic liquids based on 1-alkyl-3-methylimidazolium cations and the hydrogen sulfate (or bisulfate) anion, HSO(4)(-), are much more viscous than ionic liquids with alkyl sulfates, RSO(4)(-). The structural origin of the high viscosity of HSO(4)(-) ionic liquids is unraveled from detailed comparison of the anion Raman bands in 1-ethyl-3-methylimidazolium hydrogen sulfate and 1-butyl-3-methylimidazolium hydrogen sulfate with available data for simple HSO(4)(-) salts in crystalline phase, molten phase, and aqueous solution. Two Raman bands at 1046 and 1010 cm(-1) have been assigned as symmetric stretching modes ν(s)(S═O) of HSO(4)(-), the latter being characteristic of chains of hydrogen-bonded anions. The intensity of this component increases in the supercooled liquid phase. For comparison purposes, Raman spectra of 1-ethyl-3-methylimidazolium ethyl sulfate and 1-butyl-3-methylimidazolium methyl sulfate have been also obtained. There is no indication of difference in the strength of hydrogen bond interactions of imidazolium cations with HSO(4)(-) or RSO(4)(-) anions. Raman spectra at high pressures, up to 2.6 GPa, are also discussed. Raman spectroscopy provides evidence that hydrogen-bonded anions resulting in anion-anion interaction is the reason for the high viscosity of imidazolium ionic liquids with HSO(4)(-). If the ionic liquid is exposed to moisture, these structures are disrupted upon absorption of water from the atmosphere.

  20. Molecular simulations of imidazolium-based tricyanomethanide ionic liquids using an optimized classical force field.

    PubMed

    Vergadou, Niki; Androulaki, Eleni; Hill, Jörg-Rüdiger; Economou, Ioannis G

    2016-03-07

    Imidazolium-based ionic liquids (ILs) incorporating the tricyanomethanide ([TCM(-)]) anion are studied using an optimized classical force field. These ILs are very promising candidates for use in a wide range of cutting-edge technologies and, to our knowledge, it is the first time that this IL family is subject to a molecular simulation study with the use of a classical atomistic force field. The [C4mim(+)][TCM(-)] ionic liquid at 298.15 K and at atmospheric pressure was used as the basis for force field optimization which primarily involved the determination of the Lennard-Jones parameters of [TCM(-)] and the implementation of three quantum mechanical schemes for the calculation of the partial charge distribution and the identification of the appropriate scaling factor for the reduction of the total ionic charge. The optimized force field was validated by performing simulations of the 1-alkyl-3-methylimidazolium tricyanomethanide ([Cnmim(+)][TCM(-)], n = 2, 4, 6, and 8) IL family at various temperatures. The results for density, self-diffusivity and viscosity are in very good agreement with the available experimental data for all ILs verifying that the force field reliably reproduces the behaviour of the imidazolium-based [TCM(-)] IL family in a wide temperature range. Furthermore, a detailed analysis of the microscopic structure and the complex dynamic behaviour of the ILs under study was performed.

  1. Synthesis and antitumor activity of novel N-substituted carbazole imidazolium salt derivatives

    PubMed Central

    Liu, Lan-Xiang; Wang, Xue-Quan; Zhou, Bei; Yang, Li-Juan; Li, Yan; Zhang, Hong-Bin; Yang, Xiao-Dong

    2015-01-01

    A series of novel N-substituted carbazole imidazolium salt derivatives has been prepared and investigated for their cytotoxic activity against five human tumor cell lines by MTS assay. The results indicated that the existence of 5,6-dimethyl-benzimidazole ring, substitution of the imidazolyl-3-position with a 2-bromobenzyl or naphthylacyl group, as well as alkyl chain length between carbazole and imidazole ring were important for the antitumor activity. Compound 61, bearing a 2-bromobenzyl substituent at position-3 of the 5,6-dimethyl-benzimidazole, showed powerful inhibitory activities and was more selective to HL-60, SMMC-7721, MCF-7 and SW480 cell lines with IC50 values 0.51–2.48 μM. Mechanism of action studies revealed that this new compound could remarkably induce cell cycle arrest and apoptosis in SMMC-7721 cells. This work provides alternative novel way for future drug development based on carbazole and imidazolium salt scaffolds. PMID:26287982

  2. Why single-walled carbon nanotubes can be dispersed in imidazolium-based ionic liquids.

    PubMed

    Wang, Jinyong; Chu, Haibin; Li, Yan

    2008-12-23

    Spectroscopic and molecular modeling studies were performed to investigate the underlying dispersion mechanism of single-walled carbon nanotubes (SWCNTs) in imidazolium-based ionic liquids. Both the experimental and the simulation evidence indicate that the ionic liquids interact with SWCNTs through weak van der Waals interaction other than the previous assumed "cation-pi" interaction. Therefore the electronic structure of SWCNTs in the dispersions can be kept intrinsically. The SWCNTs do not significantly influence the local structure of the imidazolium cations, though the local environment of anions adjacent to SWCNTs is somewhat perturbed because of the interfacial effect. The ionic liquids basically keep their overall bulk phase organization. A pi-pi interaction-shielding model is proposed to account for the dispersion of SWCNTs in the ionic liquids. The ionic liquids, which possess very high dielectric constants, can effectively shield the strong pi-pi stacking interaction among SWCNTs and thus evidently disperse the SWCNTs. The retaining of SWCNTs' intrinsic property and the higher SWCNT content make the ionic liquids ideal media for the study and application of SWCNTs.

  3. Carbon Dioxide Transformation in Imidazolium Salts: Hydroaminomethylation Catalyzed by Ru-Complexes.

    PubMed

    Ali, Meher; Gual, Aitor; Ebeling, Gunter; Dupont, Jairton

    2016-08-23

    The catalytic species generated by dissolving Ru3 (CO)12 in the ionic liquids 1-n-butyl-3-methyl-imidazolium chloride or 1-n-butyl-2,3-dimethyl-imidazolium chloride are efficient multifunctional catalysts for: (a) reverse water-gas shift, (b) hydroformylation of alkenes, and (c) reductive amination of aldehydes. Thus the reaction of alkenes with primary or secondary amines (alkene/amine, 1:1) under CO2 /H2 (1:1) affords the hydroaminomethylations products in high alkene conversions (up to 99 %) and selectivities (up to 96 %). The reaction proceeds under relatively mild reaction conditions (120 °C, 60 bar=6 MPa) and affords selectively secondary and tertiary amines. The presence of amine strongly reduces the alkene hydrogenation competitive pathway usually observed in the hydroformylation of terminal alkenes by Ru complexes. The catalytic system is also highly active for the reductive amination of aldehydes and ketones yielding amines in high yields (>90 %). © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  4. Antibacterial Activity of Imidazolium-Based Ionic Liquids Investigated by QSAR Modeling and Experimental Studies.

    PubMed

    Hodyna, Diana; Kovalishyn, Vasyl; Rogalsky, Sergiy; Blagodatnyi, Volodymyr; Petko, Kirill; Metelytsia, Larisa

    2016-09-01

    Predictive QSAR models for the inhibitors of B. subtilis and Ps. aeruginosa among imidazolium-based ionic liquids were developed using literary data. The regression QSAR models were created through Artificial Neural Network and k-nearest neighbor procedures. The classification QSAR models were constructed using WEKA-RF (random forest) method. The predictive ability of the models was tested by fivefold cross-validation; giving q(2) = 0.77-0.92 for regression models and accuracy 83-88% for classification models. Twenty synthesized samples of 1,3-dialkylimidazolium ionic liquids with predictive value of activity level of antimicrobial potential were evaluated. For all asymmetric 1,3-dialkylimidazolium ionic liquids, only compounds containing at least one radical with alkyl chain length of 12 carbon atoms showed high antibacterial activity. However, the activity of symmetric 1,3-dialkylimidazolium salts was found to have opposite relationship with the length of aliphatic radical being maximum for compounds based on 1,3-dioctylimidazolium cation. The obtained experimental results suggested that the application of classification QSAR models is more accurate for the prediction of activity of new imidazolium-based ILs as potential antibacterials. © 2016 John Wiley & Sons A/S.

  5. Imidazolium Ionic Liquids as Potential Anti-Candida Inhibitors: QSAR Modeling and Experimental Studies.

    PubMed

    Hodyna, Diana; Kovalishyn, Vasyl; Rogalsky, Sergiy; Blagodatnyi, Volodymyr; Metelytsia, Larisa

    2016-01-01

    Quantitative structure-activity relationships (QSAR) of imidazolium ionic liquids (ILs) as inhibitors of C. albicans collection strains (IOA-109, KCTC 1940, ATCC 10231) have been studied. Predictive QSAR models were built using different descriptor sets for a set of 88 ionic liquids with known minimum inhibitory concentrations (MIC) against C. albicans. We applied the state-of-the-art QSAR methodologies such as WEKA Random Forest (RF) as a binary classifier, Associative Neural Networks (ASNN) and k-Nearest Neighbors (k-NN) to build continuum non-linear regression models. The obtained models were validated using a 5-fold cross-validation approach and resulted in the prediction accuracies of 80% ± 5.0 for the classification models and q2 = 0.73-0.87 for the non-linear regression models. Biological testing of newly synthesized 1,3-dialkylimidazolium ionic liquids with predicted activity was performed by disco-diffusion method against C. albicans ATCC 10231 M885 strain and clinical isolates C. albicans, C. krusei and C. glabrata strains. The high percentage of coincidence between the QSAR predictions and the experimental results confirmed the high predictive power of the developed QSAR models within the applicability domain of new imidazolium ionic liquids.

  6. Mobility and association of ions in aqueous solutions: the case of imidazolium based ionic liquids.

    PubMed

    Bešter-Rogač, Marija; Fedotova, Marina V; Kruchinin, Sergey E; Klähn, Marco

    2016-10-19

    The mobility and the mechanism of ion pairing of 1,1 electrolytes in aqueous solutions were investigated systematically on nine imidazolium based ionic liquids (ILs) from 1-methylimidazolium chloride, [MIM][Cl], to 1-dodecyl-3-methylimidazolium chloride, [1,3-DoMIM][Cl], with two isomers 1,2-dimethylimidazolium chloride, [1,2-MMIM][Cl], and 1,3-dimethylimidazolium chloride, [1,3-MMIM][Cl]. Molecular dynamics (MD) simulations, statistical mechanics calculations in the framework of the integral equation theory using one-dimensional (1D-) and three-dimensional (3D-) reference interaction site model (RISM) approaches as well as conductivity measurements were applied. From experiment and MD simulations it was found that the mobility/diffusion coefficients of cations in the limit of infinite dilution decrease with an increasing length of the cation alkyl chain, but not linearly. The aggregation tendency of cations with long alkyl chains at higher IL concentrations impedes their diffusivity. Binding free energies of imidazolium cations with the chloride anion estimated by RISM calculations, MD simulations and experiments reveal that the association of investigated ILs as model 1,1 electrolytes in water solutions is weak but evidently dependent on the molecular structure (alkyl chain length), which also strongly affects the mobility of cations.

  7. Growth inhibition and effect on photosystem by three imidazolium chloride ionic liquids in rice seedlings.

    PubMed

    Liu, Huijun; Zhang, Shuxian; Zhang, Xiaoqiang; Chen, Caidong

    2015-04-09

    The effects of three imidazolium chloride ionic liquids (ILs) including 1-octyl-3-methylimidazolium chloride ionic liquid ([OMIM]Cl), 1-decyl-3-methylimidazolium chloride ionic liquid ([DMIM]Cl) and 1-dodecyl-3-methylimidazolium chloride ionic liquid ([C12MIM]Cl) were studied in hydroponically grown rice seedlings. The growth inhibition rate increased and the Hill reaction activity of isolated rice chloroplasts decreased with increasing ILs concentrations. The IC50,5d for stem length was 0.70 mg/L of [OMIM]Cl, 0.15 mg/L of [DMIM]Cl, and 0.055 mg/L of [C12MIM]Cl, respectively. The SOD, POD and CAT activities of chloroplast exhibited initial increases followed by decreases in activity with increasing ILs concentrations. Chlorophyll fluorescence parameters such as the maximum effective quantum yield of PSII(Fv/Fm), the potential activity of PSII(Fv/F0), the yield of photochemical quantum [Y(II)], the photochemical quenching coefficient (qP), the non-photochemical quenching coefficient (NPQ) and the relative electron transport ratio (rETR) were affected, showing that ILs will damage the PSII. The results demonstrated that imidazolium chloride ILs are phytotoxic to rice growth and their photosystem, the toxicity increased as the alkyl chain length increased with the following order: [OMIM]Cl<[DMIM]Cl<[C12MIM]Cl. The results will help to better understand the possible role of the defense mechanism in rice caused by ILs exposure.

  8. Synthesis and investigation of anticancer potential of radiolabeled naphthalene monoimide bearing imidazolium salt.

    PubMed

    Yurt Lambrecht, Fatma; Ocakoglu, Kasim; Gokhan Colak, Suleyman; Alp Ersoz, Onur; Er, Ozge

    2017-01-09

    Imidazolium salts and derivatives have antitumor efficacy and toxic effects in different micro-organisms. In this study, an imidazolium bromide salt (NMI) was synthesized, and its antitumor potential was investigated by in vitro studies. Radiolabeling of synthesized NMI was carried out by iodogen method using (131) I radionuclide. The yield of radiolabeling was determined as 98.5 ± 0.1%. After that, cytotoxicity and intracellular uptake studies were evaluated in various cell lines. The cytotoxicity of NMI was determined as 35, 20, 10, and 1 μm for HEK-293, PC-3, CaCo-2, and MCF-7 cells, respectively. In addition, the intracellular uptake of (131) I-NMI was investigated in the cell lines, and the uptake was significantly found as 4 hr for MCF-7 and 6 hr for PC-3. In future studies, antitumor efficacy of (131) I-NMI on tumor-bearing animal model might be studied in light of these results.

  9. Functionalized imidazolium and benzimidazolium salts as paraoxonase 1 inhibitors: Synthesis, characterization and molecular docking studies.

    PubMed

    Karataş, Mert Olgun; Uslu, Harun; Alıcı, Bülent; Gökçe, Başak; Gencer, Nahit; Arslan, Oktay; Arslan, N Burcu; Özdemir, Namık

    2016-03-15

    Paraoxonase (PON) is a key enzyme in metabolism of living organisms and decreased activity of PON1 was acknowledged as a risk for atherosclerosis and organophosphate toxicity. The present study describes the synthesis, characterization, PON1 inhibitory properties and molecular docking studies of functionalized imidazolium and benzimidazolium salts (1a-5g). The structures of all compounds were elucidated by IR, NMR, elemental analysis and structures of compounds 2b and 2c were characterized by single-crystal X-ray diffraction. Compound 1c, a coumarin substituted imidazolium salt showed the best inhibitory effect on the activity of PON1 with good IC50 value (6.37 μM). Kinetic investigation was evaluated for this compound and results showed that this compound is competitive inhibitor of PON1 with Ki value of 2.39 μM. Molecular docking studies were also performed for most active compound 1c and one of least active compound 2c in order to determine the probable binding model into active site of PON1 and validation of the experimental results.

  10. On the Extraction of Aromatic Compounds from Hydrocarbons by Imidazolium Ionic Liquids

    PubMed Central

    Cassol, Cláudia C.; Umpierre, Alexandre P.; Ebeling, Günter; Ferrera, Bauer; Chiaro, Sandra S. X.; Dupont, Jairton

    2007-01-01

    The liquid-liquid equilibrium for the ternary system formed by n-octane and aromatic (alkylbenzenes) and heteroaromatic compounds (nitrogen and sulfur containing heterocyles) and 1-alkyl-3-methylimidazolium ionic liquids (ILs) associated with various anions has been investigated. The selectivity on the extraction of a specific aromatic compound is influenced by anion volume, hydrogen bond strength between the anion and the imidazolium cation and the length of the 1-methyl-3-alkylimidazolium alkyl side chain. The interaction of alkylbenzenes and sulfur heterocyles with the IL is preferentially through CH-π hydrogen bonds and the quantity of these aromatics in the IL phase decreases with the increase of the steric hindrance imposed by the substituents on the aromatic nucleus. In the case of nitrogen heterocycles the interaction occurs preferentially through N(heteroaromatic)-H(imidazolium) hydrogen bonds and the extraction process is largely controlled by the nitrogen heterocycle pKa. Competitive extraction experiments suggest that benzene, pyridine and dibenzothiophene do not compete for the same hydrogen bond sites of the IL.

  11. The role of the anion in the toxicity of imidazolium ionic liquids.

    PubMed

    Biczak, Robert; Pawłowska, Barbara; Bałczewski, Piotr; Rychter, Piotr

    2014-06-15

    From the environmental protection point of view, the growing interest of ionic liquids in various industrial branches has raised concerns for the toxicity assessment of these compounds. The paper discusses the effect of salts containing the shared 1-ethyl-3-methylimidazolium [EMIM] cation as coupled with five different anions: bromide [Br], nitrate [NO3], p-toluenesulfonate (tosylate) [Ts], dimethylphosphate [dMP] and methanesulfonate [MS] on the growth and development of higher land plants - spring barley and common radish. The experiment was done according to the ISO Standard 11269-2:1995 and the OECD/OCDE Guide 208/2006. As the indications of phytotoxicity, the percentage of sprouts and the level of dry and fresh plant mass were used; in addition, the visual assessment of any signs of damage to the examined plant species, such as growth inhibition and chlorotic changes, was also made. Results of our study has proved the negative impact of ILs on the tested plants and the toxic effect of imidazolium salts was dependent primarily on the applied ionic liquids concentration. The common radish revealed the higher tolerance to the imidazolium as compared to spring barley. The anion type of ionic liquid was crucial for the toxicity against common radish.

  12. Locker Room Design Trends.

    ERIC Educational Resources Information Center

    Wiens, Janet

    2001-01-01

    Examines how today's college and university athletic locker rooms have become sophisticated recruiting tools that rival many professional facilities. Locker room design and location and their level of furniture, finishes, and equipment are discussed as is the trend for more environmentally friendly locker rooms. (GR)

  13. Locker Room Design Trends.

    ERIC Educational Resources Information Center

    Wiens, Janet

    2001-01-01

    Examines how today's college and university athletic locker rooms have become sophisticated recruiting tools that rival many professional facilities. Locker room design and location and their level of furniture, finishes, and equipment are discussed as is the trend for more environmentally friendly locker rooms. (GR)

  14. Magnetic nanoparticles supported imidazolium-based ionic liquids as nanocatalyst in microwave-mediated solvent-free Biginelli reaction

    NASA Astrophysics Data System (ADS)

    Zarnegar, Zohre; Safari, Javad

    2014-08-01

    The magnetic Fe3O4 nanoparticles supported imidazolium-based ionic liquids (MNPs-IILs), namely 1-methyl-3-(3-trimethoxysilylpropyl) imidazolium hydrogen sulfate (MNPs-IIL-HSO4), 1-methyl-3-(3-trimethoxysilylpropyl) imidazolium acetate (MNPs-IIL-OAc) and 1-methyl-3-(3-trimethoxysilylpropyl) imidazolium chloride (MNPs-IIL-Cl) were used as efficient new catalysts for the one-pot synthesis of 3,4-dihydropyrimidin-2(1 H)-ones under microwave irradiation and solvent-free conditions in excellent yields. Utilization of easy reaction conditions, catalyst with high catalytic activity and good reusability, and simple magnetically work-up, makes this green protocol as an interesting option for the economic synthesis of Biginelli compounds. Microwave technology as an eco-friendly green synthetic approach has gradually been used in this organic procedure. Combining the advantages of microwave irradiation and magnetically nanocatalyst, this method provides an efficient and much improved modification of the original Biginelli reaction. We believe that this procedure appears to have a broad scope with respect to variation in the 3,4-dihydropyrimidin-2(1 H)-ones (thiones).

  15. In vitro cytotoxicity assessment of imidazolium ionic liquids: biological effects in fish Channel Catfish Ovary (CCO) cell line.

    PubMed

    Radošević, Kristina; Cvjetko, Marina; Kopjar, Nevenka; Novak, Rudjer; Dumić, Jerka; Srček, Višnja Gaurina

    2013-06-01

    Increasing interest in the application of ionic liquids as green replacement for volatile organic solvents emphasized the need for the evaluation of their toxic effects at different biological systems in order to reduce the risk for human health and environment. To our knowledge, effects of imidazolium ionic liquids on cellular level of fish cell lines have not been studied yet. The cytotoxicity of imidazolium ionic liquids containing different anions and alkyl chain lengths as the substituent at the cation ring towards the fish CCO cell line was determined by WST-1 proliferation assay. Morphological alterations were examined by fluorescent microscopy using acridine orange/ethidium bromide staining and flow cytometry analysis was also performed. The results showed concentration-dependent cytotoxicity of ionic liquids in CCO cells, related to the type of anion and alkyl chain length, while EC50 values showed moderate to high cytotoxicity of tested imidazolium ionic liquids. Distinct morphological changes observed under fluorescence microscope and data obtained by flow cytometry suggest that the toxicity of imidazolium ionic liquids with longer alkyl chains could be related to necrosis. Results presented in here may be helpful for filling existing gaps of knowledge about ionic liquids toxicity and their impact on aquatic environment.

  16. Alkyl-bis(imidazolium) salts: a new amphiphile platform that forms thermotropic and non-aqueous lyotropic bicontinuous cubic phases

    SciTech Connect

    Robertson, LA; Schenkel, MR; Wiesenauer, BR; Gin, DL

    2013-01-01

    New ionic amphiphiles with a hexyl-bridged bis(imidazolium) headgroup; Br-, BF4-, or Tf2N- anions; and a long n-alkyl tail can form thermotropic bicontinuous cubic liquid crystal phases in neat form and/or lyotropic bicontinuous cubic phases with several non-aqueous solvents or water.

  17. Radiation induced redox reactions and fragmentation of constituent ions in ionic liquids II. Imidazolium cations.

    SciTech Connect

    Shkrob, I. A.; Marin, T. W.; Chemerisov, S. D.; Hatcher, J.; Wishart, J.

    2011-04-14

    In part 1 of this study, radiolytic degradation of constituent anions in ionic liquids (ILs) was examined. The present study continues the themes addressed in part 1 and examines the radiation chemistry of 1,3-dialkyl substituted imidazolium cations, which currently comprise the most practically important and versatile class of ionic liquid cations. For comparison, we also examined 1,3-dimethoxy- and 2-methyl-substituted imidazolium and 1-butyl-4-methylpyridinium cations. In addition to identification of radicals using electron paramagnetic resonance spectroscopy (EPR) and selective deuterium substitution, we analyzed stable radiolytic products using {sup 1}H and {sup 13}C nuclear magnetic resonance (NMR) and tandem electrospray ionization mass spectrometry (ESMS). Our EPR studies reveal rich chemistry initiated through 'ionization of the ions': oxidation and the formation of radical dications in the aliphatic arms of the parent cations (leading to deprotonation and the formation of alkyl radicals in these arms) and reduction of the parent cation, yielding 2-imidazolyl radicals. The subsequent reactions of these radicals depend on the nature of the IL. If the cation is 2-substituted, the resulting 2-imidazolyl radical is relatively stable. If there is no substitution at C(2), the radical then either is protonated or reacts with the parent cation forming a C(2)-C(2) {sigma}{sigma}*-bound dimer radical cation. In addition to these reactions, when methoxy or C{sub {alpha}}-substituted alkyl groups occupy the N(1,3) positions, their elimination is observed. The elimination of methyl groups from N(1,3) was not observed. Product analyses of imidazolium liquids irradiated in the very-high-dose regime (6.7 MGy) reveal several detrimental processes, including volatilization, acidification, and oligomerization. The latter yields a polymer with m/z of 650 {+-} 300 whose radiolytic yield increases with dose (0.23 monomer units per 100 eV for 1-methyl-3-butylimidazolium

  18. Optimizing the electrochemical performance of imidazolium-based polymeric ionic liquids by varying tethering groups

    NASA Astrophysics Data System (ADS)

    Jia, Zhe

    Increasing efforts have been made in the area of sustainable alternative energy devices in the past few decades in order to develop high efficiency, low-cost electrochemical devices with sufficient long-term stability. Due to the drawbacks of conventional organic liquid electrolytes, such as leakage, volatility, flammability, and toxicity, the synthesis of solvent-free electrolyte materials has been studied world-wide. Among all the alternatives, polymer electrolytes are of great interest and have attracted many research groups. Solid-state polymer electrolytes and in particular, polymer ionic liquids (PILs), considered to be promising candidates, have been under studied widely. Ionic Liquids (ILs), defined as organic/inorganic salts with m.p. lower than 100 °C, offer good chemical stability, low flammability, negligible vapor pressure and high ionic conductivity. PILs, as the polymerized state of ILs, not only present some of the unique properties of ILs, but also benefit from the intrinsic properties of polymers, such as better thermal and chemical stability, enhanced mechanical properties, and tunable solution properties. The constrained structure of PILs may help to overcome fabrication and leakage problems associated with simple liquid electrolytes, but typically also leads to lower ionic conductivity. Once polymerized, the ionic conductivity of PILs drops substantially, usually by several orders of magnitude compared to the corresponding monomers. Therefore, to improve PILs chain mobilitiy is crucial. Previous studies suggest that a flexible tethering group should make the polymer backbone less rigid and increase electrolyte ion mobility. To investigate how tethering groups affect both electrochemical performance and physical properties of free ILs and PILs, we first report the synthesis and characterization of a novel class of imidazolium (Im) based IL model compounds and their corresponding PILs. Poly(ethylene oxide)s (PEOs), considered to be promising

  19. Radiation induced redox reactions and fragmentation of constituent ions in ionic liquids. 2. Imidazolium cations.

    PubMed

    Shkrob, Ilya A; Marin, Timothy W; Chemerisov, Sergey D; Hatcher, Jasmine L; Wishart, James F

    2011-04-14

    In part 1 of this study, radiolytic degradation of constituent anions in ionic liquids (ILs) was examined. The present study continues the themes addressed in part 1 and examines the radiation chemistry of 1,3-dialkyl substituted imidazolium cations, which currently comprise the most practically important and versatile class of ionic liquid cations. For comparison, we also examined 1,3-dimethoxy- and 2-methyl-substituted imidazolium and 1-butyl-4-methylpyridinium cations. In addition to identification of radicals using electron paramagnetic resonance spectroscopy (EPR) and selective deuterium substitution, we analyzed stable radiolytic products using (1)H and (13)C nuclear magnetic resonance (NMR) and tandem electrospray ionization mass spectrometry (ESMS). Our EPR studies reveal rich chemistry initiated through "ionization of the ions": oxidation and the formation of radical dications in the aliphatic arms of the parent cations (leading to deprotonation and the formation of alkyl radicals in these arms) and reduction of the parent cation, yielding 2-imidazolyl radicals. The subsequent reactions of these radicals depend on the nature of the IL. If the cation is 2-substituted, the resulting 2-imidazolyl radical is relatively stable. If there is no substitution at C(2), the radical then either is protonated or reacts with the parent cation forming a C(2)-C(2) σσ*-bound dimer radical cation. In addition to these reactions, when methoxy or C(α)-substituted alkyl groups occupy the N(1,3) positions, their elimination is observed. The elimination of methyl groups from N(1,3) was not observed. Product analyses of imidazolium liquids irradiated in the very-high-dose regime (6.7 MGy) reveal several detrimental processes, including volatilization, acidification, and oligomerization. The latter yields a polymer with m/z of 650 ± 300 whose radiolytic yield increases with dose (~0.23 monomer units per 100 eV for 1-methyl-3-butylimidazolium trifluorosulfonate). Gradual

  20. Electrochemical reduction of CO2 to ethylene glycol on imidazolium ion-terminated self-assembly monolayer-modified Au electrodes in an aqueous solution.

    PubMed

    Tamura, Jun; Ono, Akihiko; Sugano, Yoshitsune; Huang, Chingchun; Nishizawa, Hideyuki; Mikoshiba, Satoshi

    2015-10-21

    Imidazolium ion-terminated self-assembled monolayer (SAM)-modified electrodes achieve CO2 conversion while suppressing hydrogen evolution. Immobile imidazolium ion on gold (Au) electrodes reduce CO2 at low overpotential. The distance between electrode and imidazolium ion separated by alkane thiol affects CO2 reduction activity. CO2 reduction current depends on the tunnel current rate. Although the product of CO2 reduction at the bare Au electrode is CO, SAM-modified electrodes produce ethylene glycol in aqueous electrolyte solution without CO evolution. The faradaic efficiency reached a maximum of 87%. CO2 reduction at SAM-modified electrodes is unaffected by reduction activity of Au electrode. This phenomenon shows that the reaction field of CO2 reduction is not the electrode surface but the imidazolium ion monolayer.

  1. Fe-containing ionic liquids as effective and recoverable oxidants for dissolution of UO2 in the presence of imidazolium chlorides.

    PubMed

    Yao, Aining; Chu, Taiwei

    2013-06-21

    Imidazolium-based Fe-containing ionic liquids (ILs) can directly dissolve UO2 in the presence of their corresponding imidazolium chlorides without additional oxidants. The dissolution process follows pseudo first-order kinetics initially. Raman spectroscopic studies indicate that FeCl4(2-) is the predominant reduction product after UO2 dissolution, and attenuated total reflection-Fourier transform infrared spectroscopy indicates that the UO2(2+) complex is the principal product in the ILs. The dissolved uranyl species can be successfully separated from the Fe-containing ILs via a combination of centrifugation and solvent extraction, and also, the Fe-containing ILs can be recovered easily. In conclusion, imidazolium-based Fe-containing ionic liquids in the presence of imidazolium chlorides could be used as effective and recoverable oxidants for the dissolution of UO2.

  2. In situ determination of lignin phenolics and wood solubility in imidazolium chlorides using (31)P NMR.

    PubMed

    King, Alistair W T; Zoia, Luca; Filpponen, Ilari; Olszewska, Anna; Xie, Haibo; Kilpeläinen, Ilkka; Argyropoulos, Dimitris S

    2009-09-23

    Corn stover, Norway spruce, and Eucalyptus grandis were pulverized to different degrees. These samples were subjected to quantitative analyses, upon the basis of predissolution into the imidazolium chloride-based ionic liquids [amim]Cl and [bnmim]Cl followed by labeling of hydroxyl groups as phosphite esters and quantitative (31)P NMR analysis. Analysis of different pulverization degrees provided semiempirical data to chart the solubility of Norway spruce in these ionic liquids. Further method refinment afforded an optimized method of analysis of the lignin phenolic functionalities, without prior isolation of the lignin from the fiber. The lignin in these samples was further enriched using cellulase and acidolysis treatments, allowing for comparison with the fibrous samples. Analysis of all samples charts the polymerized-monomer availability for each stage of the treatment. Conditions required for adequate signal-to-noise ratios in the (31)P NMR analysis were established with a notable improvement observed upon the lignin enrichment steps.

  3. Imidazolium-based ionic liquids for cellulose pretreatment: recent progresses and future perspectives.

    PubMed

    Cao, Yujin; Zhang, Rubing; Cheng, Tao; Guo, Jing; Xian, Mo; Liu, Huizhou

    2017-01-01

    As the most abundant biomass in nature, cellulose is considered to be an excellent feedstock to produce renewable fuels and fine chemicals. Due to its hydrogen-bonded supramolecular structure, cellulose is hardly soluble in water and most conventional organic solvents, limiting its further applications. The emergence of ionic liquids (ILs) provides an environmentally friendly, biodegradable solvent system to dissolve cellulose. This review summarizes recent advances concerning imidazolium-based ILs for cellulose pretreatment. The structure of cations and anions which has an influence on the solubility is emphasized. Methods to assist cellulose pretreatment with ILs are discussed. The state of art of the recovery, regeneration, and reuse aspects of ILs is also presented in this work. The current challenges and development directions of cellulose dissolution in ILs are put forward. Although further studies are still much required, commercialization of IL-based processes has made great progress in recent years.

  4. Highly Efficient Catalysis of Retro-Claisen Reactions: From a Quinone Derivative to Functionalized Imidazolium Salts.

    PubMed

    Visbal, Renso; Laguna, Antonio; Gimeno, M Concepción

    2016-03-14

    A new and efficient method for the preparation of several imidazolium salts containing an ester group in the C4 position of the aromatic ring through a retro-Claisen reaction pathway between a quinone derivative and several alcohols is described. This new organic transformation proceeds in the absence of a catalyst, but it is greatly catalyzed by different Lewis acids, especially with AgOAc at a very low catalyst loading and in very short reaction times. The process takes place by the nucleophilic attack of the carbonyl groups by the alcohol functionality, thus promoting a double C-C bond cleavage and C-H and C-O bond formation. This reaction represents the first example of this type between a quinone derivative and alcohols.

  5. Supramolecular ionogel lubricants with imidazolium-based ionic liquids bearing the urea group as gelator.

    PubMed

    Yu, Qiangliang; Wu, Yang; Li, DongMei; Cai, Meirong; Zhou, Feng; Liu, Weimin

    2017-02-01

    A new class of ionic liquid gels (ionogels) is prepared through the supramolecular self-assembly of imidazolium-based ionic liquids (ILs) bearing the urea group as gelators in normal ILs. The ILs gelator can self-assemble through hydrogen bonding and hydrophobic interaction to form analogous lamellar structures and solidify base ILs. The obtained ionogels exhibit superior anticorrosion and conductivity characteristics. Moreover, ionogels show fully thermoreversible and favorable thixotropic characteristics, such that they can be used as high-performance semisolid conductive lubricants. The tribological tests reveal that these ionogels lubricants can effectively reduce the friction of sliding pairs effectively and have better tribological performance than the pure ILs under harsh conditions. Ionogel lubricants not only maintain the excellent tribological properties and conductivity of ILs, but also prevent base liquids from creeping and leakage. Therefore, ionogel lubricants can be potentially used in the conductive parts of electrical equipments.

  6. Green Imidazolium Ionics-From Truly Sustainable Reagents to Highly Functional Ionic Liquids.

    PubMed

    Tröger-Müller, Steffen; Brandt, Jessica; Antonietti, Markus; Liedel, Clemens

    2017-09-04

    We report the synthesis of task-specific imidazolium ionic compounds and ionic liquids with key functionalities of organic molecules from electro-, polymer-, and coordination chemistry. Such products are highly functional and potentially suitable for technology applications even though they are formed without elaborate reactions and from cheap and potentially green reagents. We further demonstrate the versatility of the used synthetic approach by introducing different functional and green counterions to the formed ionic liquids directly during the synthesis or after metathesis reactions. The influence of different cation structures and different anions on the thermal and electrochemical properties of the resulting ionic liquids is discussed. Our goal is to make progress towards economically competitive and sustainable task-specific ionic liquids. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  7. Structural diversity, physicochemical properties and application of imidazolium surfactants: Recent advances.

    PubMed

    Bhadani, Avinash; Misono, Takeshi; Singh, Sukhprit; Sakai, Kenichi; Sakai, Hideki; Abe, Masahiko

    2016-05-01

    The current review covers recent advances on development and investigation of cationic surfactants containing imidazolium headgroup, which are being extensively investigated for their self-aggregation properties and are currently being utilized in various conventional and non-conventional application areas. These surfactants are being used as: soft template for synthesis of mesoporous/microporous materials, drug and gene delivery agent, stabilizing agent for nanoparticles, dispersants for single/multi walled carbon nanotubes, antimicrobial and antifungal agent, viscosity modifiers, preparing nanocomposite materials, stabilizing microemulsions, corrosion inhibitors and catalyst for organic reactions. Recently several structural derivatives of these surfactants have been developed having many interesting physicochemical properties and they have demonstrated enormous potential in the area of nanotechnology, material science and biomedical science.

  8. Neighbor-Directed Histidine N (s)–Alkylation: A Route to Imidazolium-Containing Phosphopeptide Macrocycles-Biopolymers | Center for Cancer Research

    Cancer.gov

    Our recently discovered, selective, on-resin route to N(s)-alkylated imidazolium-containing histidine residues affords new strategies for peptide mimetic design. In this, we demonstrate the use of this chemistry to prepare a series of macrocyclic phosphopeptides, in which imidazolium groups serve as ring-forming junctions. Interestingly, these cationic moieties subsequently serve to charge-mask the phosphoamino acid group that directed their formation.

  9. High-Performance Ruthenium Sensitizers Containing Imidazolium Counterions for Efficient Dye Sensitization in Water.

    PubMed

    Li, Xiaoyu; Li, Shiqing; Gao, Ge; Wu, Di; Lan, Jingbo; Wang, Ruilin; You, Jingsong

    2017-07-21

    A new type of water-soluble ruthenium sensitizers incorporating imidazolium counterions, denoted [DMPI]2 -Ru and [DMHI]2 -Ru, has been developed, which can be efficiently adsorbed onto TiO2 photoanodes in aqueous solution. Owing to the good thermal stability of imidazolium, [DMPI]2 -Ru adsorbed on TiO2 has a higher decomposition temperature than N719 dye [di(tetrabutylammonium) cis-di(thiocyanato)bis(2,2'-bipyridine-4,4'-dicarboxylato)ruthenium(II)]. When using organic solvent-based I(-) /I3(-) electrolytes, solars cell based on [DMPI]2 -Ru-sensitized TiO2 in water show high power conversion efficiencies (PCE) of up to 10.2 %, which is higher than that of N719 (9.9 %) under the common conditions for dye sensitization in organic solvent. [DMHI]2 -Ru, with poorer water solubility than [DMPI]2 -Ru, gives a smaller dye-adsorption amount on TiO2 and thus a lower PCE of 9.4 %. From the viewpoint of safety and environmental impact, the fabrication of dye-sensitized solar cells (DSSCs) by using water as solvent is undoubtedly a preferable strategy. Although the [DMPI]2 -Ru-based device fabricated by using water as the solvent for both the dye-sensitization process and the electrolyte gives a relatively low efficiency, it provides a promising approach for the practical application of DSSCs. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  10. Dissolution and regeneration of hide powder/cellulose composite in Gemini imidazolium ionic liquid.

    PubMed

    Wang, Guowei; Guo, Jiarong; Zhuang, Linghua; Wang, Yan; Xu, Bin

    2015-05-01

    Gemini imidazolium ionic liquid, 3,3'-[1,2-ethanediylbis (oxy-2,1-ethanediyl)]-bis[1-methyl-imidazolium]-dibromide ([C6O2(mim)2][Br]2), was used for the dissolution and regeneration of white hide powder (from pigskin), and blend white hide powder with cellulose for the easy production of white hide powder/cellulose composite. Dissolution performance of white hide powder in [C6O2(mim)2][Br]2 was studied. The native white hide powder and [C6O2(mim)2][Br]2 regenerated white hide powder were characterized by FT-IR, XRD, DSC-TG and FE-SEM. The results showed that [C6O2(mim)2][Br]2 was a good solvent to white hide powder. The dissolution time was 55 min when the white hide powder was 8% at 120°C. The dissolution time of [C6O2(mim)2][Br]2 for white hide powder was shorter than those of common ionic liquids. The triple helical structure of white hide powder was partly destroyed during [C6O2(mim)2][Br]2 dissolution. The possible mechanism of white hide powder dissolution in [C6O2(mim)2][Br]2 and the regeneration of white hide powder in methanol had been proposed. White hide powder/cellulose composites were successfully dissolved in [C6O2(mim)2][Br]2. The performance of white hide powder/cellulose film was measured by FT-IR and TG. The tensile strength, and elongation at break of white hide powder/cellulose composite films were tested. This work demonstrated that the white hide powder/cellulose composite exhibited some potential in collagen-based tissue engineering.

  11. The role of hydrogen atoms in interactions involving imidazolium-based ionic liquids

    NASA Astrophysics Data System (ADS)

    Kempter, V.; Kirchner, B.

    2010-05-01

    In the first part of this report experimental results are discussed which focus onto the importance of hydrogen atoms in the interaction of imidazolium-based ionic liquids. These include examples for the cation-anion interaction in neat ionic liquids as well as the interactions between ionic liquids and their molecular environment, water in particular. Most of the studies emphasize the importance of the C(2)-H group of the imidazolium ring for the intra- and intermolecular interactions; commonly, the interactions of the type C-H … X (X =: O, halide) are attributed to "hydrogen bonding". In the second part it is analyzed whether these interactions and their consequences fulfill the criteria set by standard definitions of hydrogen bonding. Two cation-anion co-conformations at the C(2)-H group are found. One co-conformer (in-plane) often resembles a hydrogen bond while the other one (on-top) points to a non-hydrogen bonding behavior. Furthermore, the degree of hydrogen bonding for the in-plane structure is very dependent on the anion. Spatial distribution functions show that, in general, both co-conformations are occupied. However, the question of how long a particular co-conformer is populated in the liquid state has yet to be answered. Therefore, it is concluded that the term "hydrogen bond" should, at present, be treated with care to characterize the cation-anion contacts, because of the above-mentioned difficulties. Once more it must be stressed that oversimplifications and generalizations, even for this subclass of ionic liquids have to be avoided, because these liquids are more complicated than it appears from first sight.

  12. Solubility of CO2 and N2O in an Imidazolium-Based Lipidic Ionic Liquid.

    PubMed

    Langham, Jacob V; O'Brien, Richard A; Davis, James H; West, Kevin N

    2016-10-13

    Imidazolium-based ionic liquids have been extensively studied for their ability to dissolve a wide variety of gases and for their potential to be used as separation agents in industrial processes. For many short chain 1-alkyl-3-methylimidazolium bistriflimde salts, CO2 and N2O solublities are very similar. In this work, the solubility of CO2 and N2O has been measured in the lipidic ionic liquid 1-methyl-3-(Z-octadec-9-enyl)imidazolium bistriflimide ([oleyl-mim][NTf2]) at 298 K, 310 and 323 K up to ∼2 MPa. N2O was found to have higher solubility than CO2 under the same conditions, similar to the behavior observed when olive oil, a natural lipid, was the liquid solvent. However, the solubility of each gas on a mole fraction basis is lower in the ionic liquid than in olive oil. Comparison of the gas solubilities on a mass fraction basis demonstrates that CO2 solubility is nearly identical in both liquids; N2O solubility is higher than CO2 for both liquids, but more so in the olive oil. The difference is attributed to the high mass fraction of the olive oil that is lipid-like in character. The differential solubility of N2O/CO2 in this ionic liquid, in contrast to that of shorter chain 1-alkyl-3-methylimidazolium bistriflimide salts, gives physical insight into the solvent properties of this class of ionic liquids and provides further support for their lipid-like character.

  13. The Upstairs Room - Room for Controversy?

    ERIC Educational Resources Information Center

    Poole, Mary F.

    1973-01-01

    Doubtless everyone is tired of the subject of censorship; but I do have to give vent to my feelings when they are as intense as they are over the selection of a book as full of profanity as a Newbery honor book ( The Upstairs Room''). (Author/SM)

  14. Strengthening Weight Rooms.

    ERIC Educational Resources Information Center

    Sherman, Rachel M.

    1997-01-01

    Examines ways of giving an existing weight-training room new life without spending a lot of time and money. Tips include adding rubber floor coverings; using indirect lighting; adding windows, art work, or mirrors to open up the room; using more aesthetically pleasing ceiling tiles; upgrading ventilation; repadding or painting the equipment; and…

  15. Computer Room Water Protection.

    ERIC Educational Resources Information Center

    Price, Bennett J.

    1990-01-01

    Addresses the protection of computer rooms from water. Sources of water and potentially vulnerable areas in computer rooms are described. Water detection is then discussed, and several detection systems are detailed. Prices and manufacturers' telephone numbers for some of the systems are included. Water cleanup is also briefly considered. (MES)

  16. Strengthening Weight Rooms.

    ERIC Educational Resources Information Center

    Sherman, Rachel M.

    1997-01-01

    Examines ways of giving an existing weight-training room new life without spending a lot of time and money. Tips include adding rubber floor coverings; using indirect lighting; adding windows, art work, or mirrors to open up the room; using more aesthetically pleasing ceiling tiles; upgrading ventilation; repadding or painting the equipment; and…

  17. Unlocking the Locker Room.

    ERIC Educational Resources Information Center

    St. Clair, Dean

    1996-01-01

    Discusses locker-room design standards and common challenges when complying with the Americans with Disabilities Act. Accessibility and safety considerations for shower, toilet, and locker areas are addressed, as are entrance vestibules, drying and grooming areas, and private dressing rooms. (GR)

  18. Clean room wiping liquids

    SciTech Connect

    Harding, W.B.

    1991-12-01

    A water-based liquid containing isopropyl alcohol, ammonium hydroxide, and surfactants was developed to replace 1,1,2-trichlorotrifluoroethane for the dampening of clean room wiping cloths used to wipe clean benches, clean room equipment, and latex finger cots and gloves.

  19. Imidazolium-Functionalized Carbon Nanohorns for the Conversion of Carbon Dioxide: Unprecedented Increase of Catalytic Activity after Recycling.

    PubMed

    Calabrese, Carla; Liotta, Leonarda F; Carbonell, Esther; Giacalone, Francesco; Gruttadauria, Michelangelo; Aprile, Carmela

    2017-03-22

    Six new hybrid materials composed of carbon nanohorns (CNHs) and highly cross-linked imidazolium salts were easily synthesized using a one-step procedure based on the radical oligomerization of bis-vinylimidazolium salts (bVImiX) in the presence of pristine CNHs. The hybrid materials were characterized and employed as the sole catalysts for the conversion of carbon dioxide into cyclic carbonate by reaction with epoxides. The solids displayed excellent turnover number and productivity. Moreover, four catalysts were investigated in recycling experiments. Two catalysts containing an octyl linker between the imidazolium units and a bromide or an iodide anion showed no loss in activity after three cycles. The other two catalysts containing a p-xylyl linker and a bromide anion and different CNHs/bVImiX ratios showed an unprecedented increase of activity after recycling. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  20. Synthesis, spectroscopic and molecular docking studies of imidazolium and pyridinium based ionic liquids with HSA as potential antimicrobial agents

    NASA Astrophysics Data System (ADS)

    Trush, Maria M.; Semenyuta, Ivan V.; Vdovenko, Sergey I.; Rogalsky, Sergiy P.; Lobko, Evgeniya O.; Metelytsia, Larisa O.

    2017-06-01

    The interaction between human serum albumin (HSA) and synthesized imidazolium and pyridinium based ionic liquids (ILs), as good potential microbial growth inhibitors, was investigated by spectroscopic techniques combined with molecular docking analysis. All compounds were significant active against the tested bacterial and fungal strains. FT-IR spectroscopy indicated that the interaction of HSA with ILs generates considerable changes in protein secondary structure. The results of the molecular docking study showed that the studied ILs are able to firmly bind in the subdomain IIA of HSA with almost equal binding affinity (about -6.23 kcal/mol). Investigated HSA-ILs complex binds through hydrogen bonding or/and cation-π interactions. This study provides a better understanding of the binding of imidazolium and pyridinium based ILs to HSA and opens the way for their further biological and pharmaceutical investigations as candidates with antimicrobial properties.

  1. Modeling the solubility of carbon dioxide in imidazolium-based ionic liquids with the PC-SAFT equation of state.

    PubMed

    Chen, Yushu; Mutelet, Fabrice; Jaubert, Jean-Noël

    2012-12-13

    The goal of this work was to check the ability of the PC-SAFT equation to represent the solubility of carbon dioxide (CO(2)) in ionic liquids. Parameters of pure imidazolium-based ionic liquids were estimated using experimental densities over a large range of temperatures and then correlated with respect to the molecular weight and structure of the solvents. It was found that such a correlation is able to predict the density with high accuracy. The solubility of carbon dioxide in such ionic liquids was then studied. The binary interaction parameter k(ij) needed for the representation of such binary systems was first fitted to experimental liquid-vapor equilibria data. In a second step, a correlation based on the group contribution concept was developed to determine this temperature-dependent parameter. The ability of the model to describe accurately carbon dioxide solubility in imidazolium-based ionic liquids is demonstrated.

  2. Synthesis, characterization, and in vitro SAR evaluation of N,N'-bis(arylmethyl)-C(2)-alkyl substituted imidazolium salts.

    PubMed

    DeBord, Michael A; Wagers, Patrick O; Crabtree, Steven R; Tessier, Claire A; Panzner, Matthew J; Youngs, Wiley J

    2017-01-15

    A series of C(2)-alkyl substituted N,N'-bis(arylmethyl)imidazolium salts were synthesized, characterized, and tested for their in vitro anti-cancer activity against multiple non-small cell lung cancer cell lines by our group and the National Cancer Institute's-60 human tumor cell line screen to establish a structure-activity relationship. Compounds are related to previously published N,N'-bis(arylmethyl)imidazolium salts but utilize the historical quinoline motif and anion effects to increase the aqueous solubility. Multiple derivatives displayed high anti-cancer activity with IC50 values in the nanomolar to low micromolar range against a panel of non-small cell lung cancer cell lines. Several of these derivatives have high aqueous solubilities with potent anti-proliferative properties and are ideal candidates for future in vivo xenograft studies and have high potential to progress into clinic use.

  3. Crystal structure of 1-butyl-2,3-di-methyl-imidazolium dicarba-7,8-nido-undeca-borate.

    PubMed

    Klemes, M J; Soderstrom, L; Hunting, J L; Larsen, A S

    2015-03-01

    In the title mol-ecular salt, C9H17N2 (+)·C2H12B9 (-), the carborane cage has a bridging B-H-B bond on the open B3C2 face. The butyl side chain of the cation adopts an extended conformation [C-C-C-C = 179.6 (1)°]. In the crystal, the imidazolium ring is almost coplanar with the open face of the carborane anion. The cations stack in the [010] direction and the dihedral angle between the imidazolium rings of adjacent cations is 68.45 (6)°. The butyl chains extend into the space between carborane anions.

  4. Density and molar volumes of imidazolium-based ionic liquid mixtures and prediction by the Jouyban-Acree model

    NASA Astrophysics Data System (ADS)

    Ghani, Noraini Abd; Sairi, Nor Asrina; Mat, Ahmad Nazeer Che; Khoubnasabjafari, Mehry; Jouyban, Abolghasem

    2016-11-01

    The density of imidazolium-based ionic liquid, 1-ethyl-3-methylimidazolium diethylphosphate with sulfolane were measured at atmospheric pressure. The experiments were performed at T= (293 - 343) K over the complete mole fractions. Physical and thermodynamic properties such as molar volumes, V0, and excess molar volumes, VE for this binary mixtures were derived from the experimental density data. The Jouyban-Acree model was exploited to correlate the physicochemical properties (PCPs) of binary mixtures at various mole fractions and temperatures.

  5. An XAFS study of nickel chloride in the ionic liquid 1-ethyl-3-methyl imidazolium chloride/ aluminum chloride

    SciTech Connect

    D Roeper; G Cheek; K Pandya; W OGrady

    2011-12-31

    Nickel chloride was studied with cyclic voltammetry and X-ray absorption spectroscopy in acidic and basic aluminum chloride/1-ethyl-3-methyl imidazolium chloride (EMIC) ionic liquids. Acidic melts display metal stripping peaks which are not observed in the basic melt. EXAFS analysis shows that the nickel is tetrahedrally coordinated with chloride ions in the basic solution. In the acidic solution the nickel is coordinated by six chloride ions that are also associated with aluminum ions.

  6. Encapsulation of a catalytic imidazolium salt into avidin: towards the development of a biohybrid catalyst active in ionic liquids.

    PubMed

    Gauchot, Vincent; Branca, Mathieu; Schmitzer, Andreea

    2014-02-03

    Herein, we report the development of biohybrid catalysts that are capable of catalyzing the aldol reaction. The use of biotinylated imidazolium salts in combination with racemic or enantiomerically pure catalytic anions allowed us to study the adaptive and cooperative positioning of the anionic catalyst inside the protein. Supramolecular encapsulation of the biotinylated catalyst into avidin resulted in good selectivity for the aldol reaction performed in ionic liquid/water mixtures.

  7. Novel polystyrene microspheres functionalized by imidazolium and the electrocatalytic activity towards H2O2 of its Prussian blue composite

    NASA Astrophysics Data System (ADS)

    Mao, Hui; Song, Jinling; Zhang, Qian; Liu, Daliang; Gong, Naiqi; Li, Ying; Wu, Qiong; Verpoort, Francis; Song, Xi-Ming

    2013-05-01

    Copolymerization of styrene (St) and 1-vinyl-3-ethylimidazolium bromide (VEIB), novel poly(St-co-VEIB) microspheres were generated. Owing to the presence of imidazolium groups, such microspheres having an average diameter of 125 nm, behave electropositively when dispersed in aqueous solution. Furthermore, due to the presence of imidazolium groups, having a capacity of ion-exchange and weak reducibility on the surface of the PS microspheres, [Fe(CN)6]3- was absorbed on the surface of poly(St-co-VEIB) microspheres, and simultaneously, Fe3+ was reduced to Fe2+. Thus, in situ growth of Prussian blue (PB) nanoparticles could occur on the surface of poly(St-co-VEIB) microspheres without the addition of any other reducing agent. This methodology, utilizing the ion-exchange and weak reducibility properties of the imidazolium groups on the surface of micro-/nanostructures is a novel general method for assembling hierarchical nanostructured materials. Finally, the electrochemical property of the strawberry-like PS/PB composite microspheres was also investigated by applying a glassy carbon electrode. A good repeatability of the cyclic voltammetry responses, having a good linearity and sensitivity, for the electrocatalytic reduction of H2O2 was obtained.

  8. Shape-Controllable Formation of Poly-imidazolium Salts for Stable Palladium N-Heterocyclic Carbene Polymers

    NASA Astrophysics Data System (ADS)

    Zhao, Huaixia; Li, Liuyi; Wang, Yangxin; Wang, Ruihu

    2014-06-01

    The imidazolium-based main-chain organic polymers are one of promising platforms in heterogeneous catalysis, the size and outer morphology of polymer particles are known to have important effects on their physical properties and catalytic applications, but main-chain ionic polymers usually generate amorphous or spherical particles. Herein, we presented a versatile and facile synthetic route for size- and shape-controllable synthesis of main-chain poly-imidazolium particles. The wire-shaped, spherical and ribbon-shaped morphologies of poly-imidazolium particles were readily synthesized through quaternization of bis-(imidazol-1-yl)methane and 2,4,6-tris(4-(bromomethyl)phenyl)-1,3,5-triazine, and the modification of their size and morphology were realized through adjusting solvent polarity, solubility, concentration and temperatures. The direct complexation of the particles with Pd(OAc)2 produced ionic polymers containing palladium N-heterocyclic carbene units (NHCs) with intactness of original morphologies. The particle morphologies have a significant effect on catalytic performances. Wire-shaped palladium-NHC polymer shows excellent catalytic activity and recyclabilty in heterogeneous Suzuki-Miyaura cross-coupling reaction.

  9. Degradation of imidazolium- and quaternary ammonium-functionalized poly(fluorenyl ether ketone sulfone) anion exchange membranes.

    PubMed

    Chen, Dongyang; Hickner, Michael A

    2012-11-01

    Imidazolium and quaternary ammonium-functionalized poly(fluorenyl ether ketone sulfone)s were synthesized successfully with the same degree of cationic functionalization and identical polymer backbones for a comparative study of anion exchange membranes (AEMs) for solid-state alkaline membrane fuel cells (AMFCs). Both anion exchange membranes were synthesized using a new methyl-containing monomer that avoided the use of toxic chloromethylation reagents. The polymer chemical structures were confirmed by ¹H NMR and FTIR. The derived AEMs were fully characterized by water uptake, anion conductivity, stability under aqueous basic conditions, and thermal stability. Interestingly, both the cationic groups and the polymer backbone were found to be degraded in 1 M NaOH solution at 60 °C over 48 h as measured by changes of ion exchange capacity and intrinsic viscosity. Imidazolium-functionalized poly(fluorenyl ether ketone sulfone)s had similar aqueous alkaline stability to quaternary ammonium-functionalized materials at 60 °C but much lower stability at 80 °C. This work demonstrates that quaternary ammonium and imidazolium cationic groups are not stable on poly(arylene ether sulfone) backbones under relatively mild conditions. Additionally, the poly(arylene ether sulfone) backbone, which is one of the most common polymers used in ion exchange membrane applications, is not stable in the types of molecular configurations analyzed.

  10. Shape-Controllable Formation of Poly-imidazolium Salts for Stable Palladium N-Heterocyclic Carbene Polymers

    PubMed Central

    Zhao, Huaixia; Li, Liuyi; Wang, Yangxin; Wang, Ruihu

    2014-01-01

    The imidazolium-based main-chain organic polymers are one of promising platforms in heterogeneous catalysis, the size and outer morphology of polymer particles are known to have important effects on their physical properties and catalytic applications, but main-chain ionic polymers usually generate amorphous or spherical particles. Herein, we presented a versatile and facile synthetic route for size- and shape-controllable synthesis of main-chain poly-imidazolium particles. The wire-shaped, spherical and ribbon-shaped morphologies of poly-imidazolium particles were readily synthesized through quaternization of bis-(imidazol-1-yl)methane and 2,4,6-tris(4-(bromomethyl)phenyl)-1,3,5-triazine, and the modification of their size and morphology were realized through adjusting solvent polarity, solubility, concentration and temperatures. The direct complexation of the particles with Pd(OAc)2 produced ionic polymers containing palladium N-heterocyclic carbene units (NHCs) with intactness of original morphologies. The particle morphologies have a significant effect on catalytic performances. Wire-shaped palladium-NHC polymer shows excellent catalytic activity and recyclabilty in heterogeneous Suzuki-Miyaura cross-coupling reaction. PMID:24969738

  11. A conformational change in the peripheral anionic site of Torpedo californica acetylcholinesterase induced by a bis-imidazolium oxime.

    PubMed

    Legler, Patricia M; Soojhawon, Iswarduth; Millard, Charles B

    2015-09-01

    As part of ongoing efforts to design improved nerve agent antidotes, two X-ray crystal structures of Torpedo californica acetylcholinesterase (TcAChE) bound to the bis-pyridinium oxime, Ortho-7, or its experimental bis-imidazolium analogue, 2BIM-7, were determined. Bis-oximes contain two oxime groups connected by a hydrophobic linker. One oxime group of Ortho-7 binds at the entrance to the active-site gorge near Trp279, and the second binds at the bottom near Trp84 and Phe330. In the Ortho-7-TcAChE complex the oxime at the bottom of the gorge was directed towards the nucleophilic Ser200. In contrast, the oxime group of 2BIM-7 was rotated away from Ser200 and the oxime at the entrance induced a significant conformational change in the peripheral anionic site (PAS) residue Trp279. The conformational change alters the surface of the PAS and positions the imidazolium oxime of 2BIM-7 further from Ser200. The relatively weaker binding and poorer reactivation of VX-inhibited, tabun-inhibited or sarin-inhibited human acetylcholinesterase by 2BIM-7 compared with Ortho-7 may in part be owing to the unproductively bound states caught in crystallo. Overall, the reactivation efficiency of 2BIM-7 was comparable to that of 2-pyridine aldoxime methyl chloride (2-PAM), but unlike 2-PAM the bis-imidazolium oxime lacks a fixed charge, which may affect its membrane permeability.

  12. Degradation of Imidazolium- and Quaternary Ammonium-Functionalized Poly(fluorenyl ether ketone sulfone) Anion Exchange Membranes

    SciTech Connect

    Chen, DY; Hickner, MA

    2012-11-01

    Imidazolium and quaternary ammonium-functionalized poly(fluorenyl ether ketone sulfone)s were synthesized successfully with the same degree of cationic functionalization and identical polymer backbones for a comparative study of anion exchange membranes (AEMs) for solid-state alkaline membrane fuel cells (AMFCs). Both anion exchange membranes were synthesized using a new methyl-containing monomer that avoided the use of toxic chloromethylation reagents. The polymer chemical structures were confirmed by H-1 NMR and FTIR. The derived AEMs were fully characterized by water uptake, anion conductivity, stability under aqueous basic conditions, and thermal stability. Interestingly, both the cationic groups and the polymer backbone were found to be degraded in 1 M NaOH solution at 60 degrees C over 48 h as measured by changes of ion exchange capacity and intrinsic viscosity. Imidazolium-functionalized poly(fluorenyl ether ketone sulfone)s had similar aqueous alkaline stability to quaternary ammonium-functionalized materials at 60 degrees C but much lower stability at 80 degrees C. This work demonstrates that quaternary ammonium and imidazolium cationic groups are not stable on poly(arylene ether sulfone) backbones under relatively mild conditions. Additionally, the poly(arylene ether sulfone) backbone, which is one of the most common polymers used in ion exchange membrane applications, is not stable in the types of molecular configurations analyzed.

  13. Performance enhancement of dye-sensitized solar cells using an ester-functionalized imidazolium iodide as the solid state electrolyte.

    PubMed

    Xu, Xin; Wang, Hong; Gong, Feng; Zhou, Gang; Wang, Zhong-Sheng

    2013-04-24

    Linking an ester group to the imidazolium ring has been demonstrated to improve solar cell performance in terms of short-circuit photocurrent (Jsc), open-circuit photovoltage (Voc), and fill factor (FF) in particular, when the imidazolium iodide mixed with iodine and LiI is used as a solid state electrolyte of dye-sensitized solar cells. Herein, the effect of ester group on solar cell performance has been investigated by means of intensity modulated photocurrent/photovoltage and electrochemical impedance spectroscopy. From the alkyl- to ester-functionalized imidazolium iodide, the increase in Jsc is attributed to the increased charge collection efficiency due to the enhanced conductivity, the increase in Voc is caused by the upward shift of conduction band edge of TiO2, which compensates for the voltage loss arising from the higher charge recombination rate, and the remarkable increase in FF is attributed to the decreased series resistance along with the increased Voc and decreased diode quality factor.

  14. Operating Room Fire Safety

    PubMed Central

    Hart, Stuart R.; Yajnik, Amit; Ashford, Jeffrey; Springer, Randy; Harvey, Sherry

    2011-01-01

    Operating room fires are a rare but preventable danger in modern healthcare operating rooms. Optimal outcomes depend on all operating room personnel being familiar with their roles in fire prevention and fire management. Despite the recommendations of major safety institutes, this familiarity is not the current practice in many healthcare facilities. Members of the anesthesiology and the surgery departments are commonly not actively involved in fire safety programs, fire drills, and fire simulations that could lead to potential delays in prevention and management of intraoperative fires. PMID:21603334

  15. [Single-patient rooms].

    PubMed

    Jensen, Elisabeth Brøgger

    2009-05-18

    The Danish government has allocated funding to achieve the goal of replacing 50% of all existing hospital buildings by new facilities. Facing such a building boom, the debate for and against single-patient rooms is in progress. A review of the literature shows that single-patient rooms have a direct impact on patient safety. Patient Safety Leadership Walkrounds and failure modes and effects analysis can be used for identifying risks before designing single rooms in future hospitals. The acuity adaptability model needs to be revised.

  16. Transformer room fire tests

    NASA Astrophysics Data System (ADS)

    Fustich, C. D.

    1980-03-01

    A series of transformer room fire tests are reported to demonstate the shock hazard present when automatic sprinklers operate over energized electrical equipment. Fire protection was provided by standard 0.5 inch pendent automatic sprinklers temperature rated at 135 F and installed to give approximately 150 sq ft per head coverage. A 480 v dry transformer was used in the room to provide a three phase, four wire distribution system. It is shown that the induced currents in the test room during the various tests are relatively small and pose no appreciable personnel shock hazard.

  17. Effect of -OH functionalization, C2 methylation, and high radiation fields on the non-linear optical response of imidazolium ionic liquids

    NASA Astrophysics Data System (ADS)

    Namboodiri, Vinu V.; Guleria, Apurav; Singh, Ajay K.

    2017-04-01

    Considering the impending applications of room temperature ionic liquids (RTILs) in various areas involving high optical and radiation fields, it is pertinent to probe the structure-property correlation of these solvents exposed to such conditions. Herein, femtosecond Z-scan technique (at high pulse repetition rate, 80 MHz) was employed to investigate the non-linear optical response of imidazolium RTILs in 3 scenarios: (1) -OH functionalization, (2) C2 methylation, and (3) influence of high radiation fields. Large negative non-linear refractive values ( n 2) were observed in all the RTIL samples and have been attributed predominantly due to the thermal effects. In order to isolate and determine the contribution of electronic Kerr effect, the Z-scan experiments were also carried out at low pulse repetition rate (i.e. 500 Hz) by means of a mechanical chopper. The closed aperture transmittance profile showed the valley-peak pattern, which signifies positive non-linearity. Nonetheless, the variation in the n2 values of the RTILs follows the same trend in low pulse repetition rate as was observed in case of high pulse repetition rate. The trend in the n 2 values clearly showed the decrease in the non-linearity in the first two cases and has been attributed to the weakening of the ion-pair formation, which adversely affects the charge transfer between the ionic moieties via C2 position. However, an increase in the n 2 values was observed in case of ILs irradiated to high radiation doses. This enhancement in the non-linearity has been assigned to the formation of double bond order radiolytic products. These results clearly indicate a strong correlation between the non-linearity and the strength of cation-anion interaction amongst them. Therefore, such information about these solvents may significantly contribute to the fundamental understanding of their structure-property relationships.

  18. 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. Copyright © 2011 Elsevier B.V. All rights reserved.

  19. Central room (delivery room on plan) between the east and ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    Central room (delivery room on plan) between the east and west reading rooms, showing built-in card catalog drawers. View to south. - Sacramento Junior College, Library, 3835 Freeport Boulevard, Sacramento, Sacramento County, CA

  20. Men's toilet (room 207, representing rooms 306, 406, and 506; ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    Men's toilet (room 207, representing rooms 306, 406, and 506; also women's toilets, rooms 102, 104, 204, 204A, 303, 403, and 503), looking north. - California State Office Building No. 1, 915 Capitol Mall, Sacramento, Sacramento County, CA

  1. Interior. Balance room for chemistry laboratory. Storage room for glassware ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    Interior. Balance room for chemistry laboratory. Storage room for glassware and reference room with frequently used chemistry and chemical engineering texts. - Thomas A. Edison Laboratories, Building No. 2, Main Street & Lakeside Avenue, West Orange, Essex County, NJ

  2. QUARTERS B, DINING ROOM. LIVING ROOM ON LEFT AND KITCHEN ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    QUARTERS B, DINING ROOM. LIVING ROOM ON LEFT AND KITCHEN TO RIGHT SHOWING DOORS TO LIVING ROOM. - Naval Magazine Lualualei, West Loch Branch, Warrant Officers & Civilian Quarters, B Avenue, Pearl City, Honolulu County, HI

  3. Interior. Balance room for chemistry laboratory. Storage room for glassware ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    Interior. Balance room for chemistry laboratory. Storage room for glassware and reference room with frequently used chemistry and chemical engineering texts. - Thomas A. Edison Laboratories, Building No. 2, Main Street & Lakeside Avenue, West Orange, Essex County, NJ

  4. Carpenter in White Room

    NASA Technical Reports Server (NTRS)

    1962-01-01

    Inside Hangar S at the White Room Facility at Cape Canaveral, Florida, Mercury astronaut M. Scott Carpenter examines the honeycomb protective material on the main pressure bulkhead (heat shield) of his Mercury capsule nicknamed 'Aurora 7.'

  5. 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.

  6. Thickness-dependent structural arrangement in nano-confined imidazolium-based ionic liquid films

    SciTech Connect

    Rouha, Michael; Cummings, Peter T.

    2014-12-24

    Here we report that a fundamental understanding of interfacial processes in nano-confined ionic liquids is crucial to increase the performance of modern energy storage devices. It is well-known that interfaces between electrodes and ionic liquids exhibit structures distinct from that of the bulk liquid. Following the recent interest in these systems, we studied the structure of thin ionic liquid films confined in flexible uncharged carbon nano-pores by using fully-atomistic molecular dynamics simulations. We show that the interfacial ions self-assemble into a closely-packed chequerboard-like pattern, formed by both cations and anions in direct contact with the pore wall, and that within this structure we find changes dependent on the thickness of the confined films. At low coverages a dense layer is formed in which both the imidazolium-ring and its alkyl-tail lie parallel to the pore wall. With increasing coverage the alkyl-chains reorient perpendicular to the surface, making space for additional ions until a densified highly ordered layer is formed. This wall-induced self-patterning into interfacial layers with significantly higher than bulk density is consistent with recent experimental and theoretical studies of similar systems. Lastly, this work reveals additional molecular-level details on the effect of the film-thickness on the structure and density of the ionic liquid.

  7. Thickness-dependent structural arrangement in nano-confined imidazolium-based ionic liquid films

    DOE PAGES

    Rouha, Michael; Cummings, Peter T.

    2014-12-24

    Here we report that a fundamental understanding of interfacial processes in nano-confined ionic liquids is crucial to increase the performance of modern energy storage devices. It is well-known that interfaces between electrodes and ionic liquids exhibit structures distinct from that of the bulk liquid. Following the recent interest in these systems, we studied the structure of thin ionic liquid films confined in flexible uncharged carbon nano-pores by using fully-atomistic molecular dynamics simulations. We show that the interfacial ions self-assemble into a closely-packed chequerboard-like pattern, formed by both cations and anions in direct contact with the pore wall, and that withinmore » this structure we find changes dependent on the thickness of the confined films. At low coverages a dense layer is formed in which both the imidazolium-ring and its alkyl-tail lie parallel to the pore wall. With increasing coverage the alkyl-chains reorient perpendicular to the surface, making space for additional ions until a densified highly ordered layer is formed. This wall-induced self-patterning into interfacial layers with significantly higher than bulk density is consistent with recent experimental and theoretical studies of similar systems. Lastly, this work reveals additional molecular-level details on the effect of the film-thickness on the structure and density of the ionic liquid.« less

  8. A green approach for starch modification: Esterification by lipase and novel imidazolium surfactant.

    PubMed

    Adak, Sunita; Banerjee, Rintu

    2016-10-05

    Starch being one of the most abundant polysaccharides in nature has been subjected to modification to enhance its applicability. Modification by esterification involves acylation of hydroxyl groups of glucose units to form starch esters. Lipases, as catalysts have emerged as a promising alternative to chemical processes. Although ionic liquids and microwave assisted heating are emerging as green technology yet their use along with lipases for starch modification has not been probed. In the present study esterification of corn starch employing Rhizopus oryzae lipase, microwave irradiation and novel imidazolium surfactants has been attempted. At 80% irradiation, 1:3 starch/oleic acid molar ratio, 150 IU enzyme, and 50μmol of [C16-3-C16im]Br2 maximum degree of substitution (DS=2.75) was attained. The modified starch showed better hydrophobicity and thermoplasticity with corresponding structural changes depicted by FTIR, XRD and SEM. These properties advocate the usefulness of the modified starch in food and biopolymer sectors.

  9. Pyrazolium- versus imidazolium-based ionic liquids: structure, dynamics and physicochemical properties.

    PubMed

    Chiappe, Cinzia; Sanzone, Angelo; Mendola, Daniele; Castiglione, Franca; Famulari, Antonino; Raos, Guido; Mele, Andrea

    2013-01-17

    Ionic liquids (ILs) composed of two different pyrazolium cations with dicyanamide and bis(trifluoromethanesulfonyl)imide anions have been synthesized and characterized by NMR, Kamlet-Taft solvatochromic parameters, conductivity and rheological measurements, as well as ab initio calculations. Density functional calculations for the two pyrazolium cations, 1-butyl-2-methylpyrazolium [bmpz] and 1-butyl-2,3,5-trimethylpyrazolium [bm(3)pz], provide a full picture of their conformational states. Homo- and heteronuclear NOE show aggregation motives sensitive to steric hindrance and the anions' nature. Self-diffusion coefficients D for the anion and the cation have been measured by pulsed field gradient spin-echo NMR (PGSE-NMR). The ionic diffusivity is influenced by their chemical structure and steric hindrance, giving the order D(cation) > D(anion) for all of the examined compounds. The measured ion diffusion coefficients, viscosities, and ionic conductivity follow the Vogel-Fulcher-Tammann (VFT) equation for the temperature dependencies, and the best-fit parameters have been determined. Solvatochromic parameters indicate an increased ion association upon going from bis(trifluoromethanesulfonyl)imide to dicyanamide-based pyrazolium salts, as well as specific hydrogen bond donor capability of H atoms on the pyrazolium ring. All of these physical properties are compared to those of an analogous series of imidazolium-based ILs.

  10. CO2 capture on NiO supported imidazolium-based ionic liquid

    NASA Astrophysics Data System (ADS)

    Marliza, Tengku Sharifah; Yarmo, Mohd Ambar; Hakim, Azizul; Tahari, Maratun Najiha Abu; Hisham, Mohamed Wahab Mohamed; Taufiq-Yap, Yun Hin

    2017-05-01

    CO2 capture on NiO supported imidazolium-based ionic liquid, NiO/[emim][HSO4]/SiO2 as an adsorbent was investigated using gas adsorption analyzer and physicochemical properties of the adsorbent were characterized using X-ray powder diffraction (XRD), surface area analyzer (BET method) and temperature-program-desorption analysis (TPD). Immobilization of ionic liquid on silica, [emim][HSO4]/SiO2 slightly decreased the surface area compared to bare silica from 266 to 256 m2/g due to the pore blocking by the confinement of IL in SiO2 pore. Interestingly, introduction of NiO on supported ionic liquid, NiO/[emim][HSO4]/SiO2 was increased the surface area as well as pore volume from 256 to 356 m2/g and 0.14 to 0.38 cm3/g, respectively. The enhancement of surface area and pore volume was significantly increased the CO2 adsorption performance with capacity of 48.8 mg CO2/g adsorbent compared to [emim][HSO4]/SiO2 27.3 mg CO2/g adsorbent).

  11. The role of the cation in the solvation of cellulose by imidazolium-based ionic liquids.

    PubMed

    Rabideau, Brooks D; Agarwal, Animesh; Ismail, Ahmed E

    2014-02-13

    We present a systematic molecular dynamics study examining the roles of the individual ions of different alkylimidazolium-based ionic liquids in the solvation of cellulose. We examine combinations of chloride, acetate, and dimethylphosphate anions paired with cations of increasing tail length to elucidate the precise role of the cation in solvating cellulose. In all cases we find that the cation interacts with the nonpolar domains of cellulose through dispersion interactions, while interacting electrostatically with the anions bound at the polar domains of cellulose. Furthermore, the structure and dimensions of the imidazolium head facilitate the formation of large chains and networks of alternating cations and anions that form a patchwork, satisfying both the polar and nonpolar domains of cellulose. A subtle implication of increasing tail length is the dilution of the anion concentration in the bulk and at the cellulose surface. We show how this decreased concentration of anions in the bulk affects hydrogen bond formation with cellulose and how rearrangements from single hydrogen bonds to multiple shared hydrogen bonds can moderate the loss in overall hydrogen bond numbers. Additionally, for the tail lengths examined in this study we observe only a very minor effect of tail length on the solvation structure and overall interaction energies.

  12. Role of spacer length in interaction between novel gemini imidazolium surfactants and Rhizopus oryzae lipase.

    PubMed

    Adak, Sunita; Datta, Sougata; Bhattacharya, Santanu; Banerjee, Rintu

    2015-11-01

    An insight into the effects of new ionic liquid-type gemini imidazolium cationic surfactants on the structure and function of the lipases is of prime importance for their potential application. Changes in the activity, stability and structure of Rhizopus oryzae lipase in the presence of novel gemini surfactants, [C16-3-C16im]Br2 and [C16-12-C16im]Br2 were probed in the present study. Surfactant with shorter spacer length, [C16-3-C16im]Br2 was found to be better in improving the hydrolytic activity and thermal stability of the lipase. For both the surfactants, activation was concentration dependent. CD spectroscopy results showed a decrease in α-helix and an increase in β-sheet content in the presence of these surfactants. A higher structural change observed in presence of [C16-12-C16im]Br2 correlated with lower enzyme activity. Isothermal titration calorimetric studies showed the binding to be spontaneous in nature based on sequential two site binding model. The forces involved in binding were found to differ for the two surfactants proving that the spacer length is an important factor which governs the interaction. These surfactants could be used as promising components both in enzyme modification and media engineering for attaining the desired goals in biocatalytic reactions. Copyright © 2015 Elsevier B.V. All rights reserved.

  13. Investigation on growth and characterization of imidazolium picrate: An organic salt

    NASA Astrophysics Data System (ADS)

    Anandhi, S.; Shyju, T. S.; Srinivasan, T. P.; Gopalakrishnan, R.

    2011-11-01

    Organic crystal of imidazolium picrate (IP) was synthesized and successfully grown by the slow cooling solution growth method using ethanol and acetone as solvents. The structural, thermal, optical and mechanical properties were studied for the grown crystal. Cell parameters were determined using X-ray diffraction studies. HRXRD study shows the crystalline perfection. FT-IR and laser Raman studies confirm the functional groups present in the title material. The optical properties such as optical bandgap and refractive index of the title material were obtained from the UV-visible spectrum. The PL spectrum of the title compound shows green emission. The thermal stability of the crystal has been determined using TG/DTA studies. Vicker's microhardness studies were carried out to understand the mechanical properties of the grown crystal. The hardness of the title compound increases on increasing the load. Theoretical factor group analysis enumerates the possible modes of vibrations. The dielectric tensor, dielectric loss and conductivity over a range of frequencies and temperatures have been presented. Dielectric tensor components have been determined theoretically using the DFT theory.

  14. Preparation and evaluation of a novel hybrid monolithic column based on pentafluorobenzyl imidazolium bromide ionic liquid.

    PubMed

    Shan, Yuanhong; Qiao, Lizhen; Shi, Xianzhe; Xu, Guowang

    2015-01-02

    To develop a novel hybrid monolithic column based on pentafluorobenzyl imidazolium bromide ionic liquid, a new ionic liquid monomer was synthesized from 1-vinylimidazole and pentafluorobenzyl bromide. By employing a facile one-step copolymerization of polyhedral-oligomeric-silsesquioxane-type (POSS) cross-linking agent and the home-made ionic liquid monomer, the hybrid monolithic columns were in situ fabricated in fused-silica capillary. The morphology of monolithic column was characterized by scanning electron microscope (SEM) and the chemical composition was confirmed by Fourier-transform infrared spectroscopy (FT-IR) and elemental analysis. Excellent mechanical stability and slight swelling propensity were exhibited which was ascribed to the rigid hybrid monolithic skeleton. Reproducibility results of run-to-run, column-to-column, batch-to-batch and day-to-day were investigated and the RSDs were less than 0.46%, 1.84%, 3.96% and 3.17%, respectively. The mixed-mode retention mechanism with hydrophobic interaction, π-π stacking, ion-exchange, electrostatic interaction and dipole-dipole interaction was explored systematically using analytes with different structure types. Satisfied separation capability and column efficiency were achieved for the analysis of small molecular compounds such as alkylbenzenes, polycyclic aromatic hydrocarbons, nucleosides and halogenated compounds. Copyright © 2014 Elsevier B.V. All rights reserved.

  15. [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.

  16. Effects of imidazolium chloride ionic liquids and their toxicity to Scenedesmus obliquus.

    PubMed

    Liu, Huijun; Zhang, Xiaoqiang; Chen, Caidong; Du, Shaoting; Dong, Ying

    2015-12-01

    The low volatility of ionic liquids effectively eliminates a major pathway for environmental release and contamination; however, the good solubility, low degree of environmental degradation and biodegradation of ILs may pose a potential threat to the aquatic environment. The growth inhibition of the green alga Scenedesmus obliquus by five 1-alkyl-3-methylimidazolium chloride ionic liquids (ILs) ([Cnmim]Cl, n=6, 8, 10, 12, 16) was investigated, and the effect on cellular membrane permeability and the ultrastructural morphology by ILs ([Cnmim]Cl, n=8, 12, 16) were studied. The results showed that the growth inhibition rate increased with increasing IL concentration and increasing alkyl chain lengths. The relative toxicity was determined to be [C6mim]Cl<[C8mim]Cl<[C10mim]Cl<[C12mim]Cl<[C16mim]Cl. The algae were most sensitive to imidazolium chloride ILs at 48 h according to the results from the growth inhibition rate and cellular membrane permeability tests. The ultrastructural morphology showed that the ILs had negative effects on the cellular morphology and structure of the algae. The cell wall of treated algae became wavy and separated from the cell membrane. Chloroplast grana lamellae became obscure and loose, osmiophilic material was deposited in the chloroplast, and mitochondria and their cristae swelled. Additionally, electron-dense deposits were observed in the vacuoles.

  17. Imidazolium ionic liquids as solvents of pharmaceuticals: influence on HSA binding and partition coefficient of nimesulide.

    PubMed

    Azevedo, Ana M O; Ribeiro, Diogo M G; Pinto, Paula C A G; Lúcio, Marlene; Reis, Salette; Saraiva, M Lúcia M F S

    2013-02-25

    In this work, the influence of imidazolium ionic liquids (ILs) on bio-chemical parameters that influence the in vivo behavior of nimesulide was evaluated. In this context, the binding of nimesulide to human serum albumin (HSA), in IL media, was studied. In parallel, the evaluation of the interaction of drug-IL systems, with micelles of hexadecylphosphocholine (HDPC), enabled the calculation of partition coefficients (K(p)). Both assays were performed in buffered media in the absence and in the presence of emim [BF(4)], emim [Ms] and emim [TfMs] 1%. Even though there was an increase of the dissociation constant (K(d)) in IL media, nimesulide still binds to HSA by means of strong interactions. The thermodynamic analysis indicates that the interaction is spontaneous for all the tested systems. Moreover, the studied systems exhibited properties that are favorable to the interaction of the drug with biological membranes, with K(p) values 2.5-3.5 higher than in aqueous environment. The studied nimesulide-IL systems presented promising characteristics regarding the absorption and distribution of the drug in vivo, so that the studied solvents seem to be good options for drug delivery.

  18. The Biginelli reaction with an imidazolium-tagged recyclable iron catalyst: kinetics, mechanism, and antitumoral activity.

    PubMed

    Ramos, Luciana M; Guido, Bruna C; Nobrega, Catharine C; Corrêa, José R; Silva, Rafael G; de Oliveira, Heibbe C B; Gomes, Alexandre F; Gozzo, Fábio C; Neto, Brenno A D

    2013-03-25

    The present work describes the synthesis, characterization, and application of a new ion-tagged iron catalyst. The catalyst was employed in the Biginelli reaction with impressive performance. High yields have been achieved when the reaction was carried out in imidazolium-based ionic liquids (BMI⋅PF6, BMI⋅NTf2, and BMI⋅BF4), thus showing that the ionic-liquid effects play a role in the reaction. Moreover, the ion-tagged catalyst could be recovered and reused up to eight times without any noticeable loss in activity. Mechanistic studies performed by using high-resolution electrospray-ionization quadrupole-time-of-flight mass (HR-EI-QTOF) spectrometry and kinetic experiments indicate only one reaction pathway and rule out the other two possibilities under the development conditions. The theoretical calculations are in accordance with the proposed mechanism of action of the iron catalyst. Finally, the 37 dihydropyrimidinone derivatives, products of the Biginelli reaction, had their cytotoxicity evaluated in assays against MCF-7 cancer cell linages with encouraging results of some derivatives, which were virtually non-toxic against healthy cell linages (fibroblasts).

  19. Catalyst life in imidazolium-based ionic liquids for palladium-catalysed asymmetric allylic alkylation.

    PubMed

    Guerrero-Ríos, I; Martin, E

    2014-05-28

    A Pd/(S)-BINAP system was successfully applied to the asymmetric allylic alkylation of rac-1,3-diphenyl-3-acetoxyprop-1-ene () using imidazolium-based ionic liquids (ILs) attaining up to 225 h(-1) TOF and 88% ee of the (R)-product. Although the system was barely active in the recycling experiments, the catalyst life was confirmed after recharging the system with substrate/reactants resulting in an alkylated product. In the latter case, the conversion rates and enantiomeric excesses were similar or lower compared to those in the first cycle. In order to explain the observed catalyst performance in the recycling as well as in the recharging experiments, we investigated the reactivity between the catalyst precursors, substrate and reactants in ILs. We were able to identify the species involved in the catalytic reactions under various conditions by means of (31)P NMR analyses. Allylpalladium intermediates () were found to be the active and selective species at a high substrate concentration. When the substrate was consumed, competing reactions took place leading to different palladium complexes. [PdCl(NHC(Bu,Me))((S)-BINAP)]Cl (), together with [Pd((S)-BINAP)2] (), were recognised as the species responsible for the loss of activity, meanwhile, the decrease in enantioselectivity was accounted for by the formation of mixed (NHC)(monophosphine)-palladium species.

  20. DFT study of the energetic and noncovalent interactions between imidazolium ionic liquids and hydrofluoric acid.

    PubMed

    Velarde, Marco V; Gallo, Marco; Alonso, P A; Miranda, A D; Dominguez, J M

    2015-04-16

    In this work, we evaluated the energetic interactions between imidazolium ionic liquids (ILs) and hydrofluoric acid, as well as the cation-anion interactions in ILs. We used DFT calculations that include dispersion corrections employing the PBE and M06 functionals. We tested 22 ILs, including [C4MIM][PF6], [C4MIM][NTf2], and [C4MIM][CH3COO], obtaining interaction energies in the range of -27 to -13 kcal/mol with the PBE functional. The NCI (noncovalent interaction) index developed by Yang and collaborators ( J. Am. Chem. Soc. 2010 , 132 , 6498 - 6506 ; J. Chem. Theory Comput. 2011 , 7 , 625 - 632 ) also was used for mapping the key noncovalent interactions (hydrogen bonds, van der Waals, and steric repulsions) between the anions and cations of ILs and also for interactions of ILs with hydrofluoric acid (HF). The results obtained show that the anions have a stronger effect with respect to cations in their capacity for interacting with hydrofluoric acid, and the strongest interaction energies occur in systems where the key noncovalent interactions are mainly hydrogen bonds. The [C4MIM][PF6], [C4MIM][NTf2], and [C4MIM][BF4] ionic liquids displayed the weakest cation-anion interactions.

  1. Thickness-dependent structural arrangement in nano-confined imidazolium-based ionic liquid films.

    PubMed

    Rouha, Michael; Cummings, Peter T

    2015-02-14

    A fundamental understanding of interfacial processes in nano-confined ionic liquids is crucial to increase the performance of modern energy storage devices. It is well-known that interfaces between electrodes and ionic liquids exhibit structures distinct from that of the bulk liquid. Following the recent interest in these systems, we studied the structure of thin ionic liquid films confined in flexible uncharged carbon nano-pores by using fully-atomistic molecular dynamics simulations. We show that the interfacial ions self-assemble into a closely-packed chequerboard-like pattern, formed by both cations and anions in direct contact with the pore wall, and that within this structure we find changes dependent on the thickness of the confined films. At low coverages a dense layer is formed in which both the imidazolium-ring and its alkyl-tail lie parallel to the pore wall. With increasing coverage the alkyl-chains reorient perpendicular to the surface, making space for additional ions until a densified highly ordered layer is formed. This wall-induced self-patterning into interfacial layers with significantly higher than bulk density is consistent with recent experimental and theoretical studies of similar systems. This work reveals additional molecular-level details on the effect of the film-thickness on the structure and density of the ionic liquid.

  2. Imidazolium-based poly(ionic liquid)s as new alternatives for CO2 capture.

    PubMed

    Privalova, Elena I; Karjalainen, Erno; Nurmi, Mari; Mäki-Arvela, Päivi; Eränen, Kari; Tenhu, Heikki; Murzin, Dmitry Yu; Mikkola, Jyri-Pekka

    2013-08-01

    Solid imidazolium-based poly(ionic liquid)s with variable molecular weights that contain the poly[2-(1-butylimidazolium-3-yl)ethyl methacrylate] (BIEMA) cation and different counter anions were evaluated in terms of CO2 capture and compared with classical ionic liquids with similar counter anions. In addition to poly(ionic liquid)s with often-applied ions such as BF4 (-) , PF6 (-) , NTf2 (-) , trifluoromethanesulfonate (OTf(-) ) and Br(-) , for the first time [BIEMA][acetate] was synthesised, which revealed a remarkably high CO2 sorption performance that exceeded the poly(ionic liquid)s studied previously on average by a factor of four (12.46 mg gPIL (-1) ). This study provides an understanding of the factors that affect CO2 sorption and a comparison of the CO2 capture efficiency with the frequently used sorbents. Moreover, all the studied sorbents were reusable if regenerated under carefully selected conditions and can be considered as suitable candidates for CO2 sorption. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  3. Thermodynamical and structural properties of imidazolium based ionic liquids from molecular simulation

    NASA Astrophysics Data System (ADS)

    Raabe, Gabriele; Köhler, Jürgen

    2008-04-01

    We have performed molecular dynamics simulations to determine the densities and heat of vaporization as well as structural information for the 1-alkyl-3-methyl-imidazolium based ionic liquids [amim][Cl] and [amim][BF4] in the temperature range from 298to363K. In this simulation study, we used an united atom model of Liu et al. [Phys. Chem. Chem. Phys. 8, 1096 (2006)] for the [emim+] and [bmim+] cations, which we have extended for simulation in [hmim]-ILs and combined with parameters of Canongia Lopes et al. [J. Phys. Chem. B 108, 2038 (2004)] for the [Cl-] anion. Our simulation results prove that both the original united atoms approach by Liu et al. and our extension yield reasonable predictions for the ionic liquid with a considerably reduced computational expense than that required for all atoms models. Radial distribution functions and spatial distribution functions where employed to analyze the local structure of this ionic liquid, and in which way it is influenced by the type of the anion, the size of the cation, and the temperature. Our simulations give evidence for the occurrence of tail aggregations in these ionic liquids with increasing length of the side chain and also increasing temperature.

  4. Growth, crystalline perfection, spectral, thermal and theoretical studies on imidazolium L-tartrate crystals.

    PubMed

    Meena, K; Muthu, K; Meenatchi, V; Rajasekar, M; Bhagavannarayana, G; Meenakshisundaram, S P

    2014-04-24

    Transparent optical quality single crystals of imidazolium L-tartrate (IMLT) were grown by conventional slow evaporation solution growth technique. Crystal structure of the as-grown IMLT was determined by single crystal X-ray diffraction analysis. Thermal analysis reveals the purity of the crystal and the sample is stable up to the melting point. Good transmittance in the visible region is observed and the band gap energy is estimated using diffuse reflectance data by the application of Kubelka-Munk algorithm. The powder X-ray diffraction study reveals the crystallinity of the as-grown crystal and it is compared with that of the experimental one. An additional peak in high resolution X-ray diffraction (HRXRD) indicates the presence of an internal structural low angle boundary. Second harmonic generation (SHG) activity of IMLT is significant as estimated by Kurtz and Perry powder technique. HOMO-LUMO energies and first-order molecular hyperpolarizability of IMLT have been evaluated using density functional theory (DFT) employing B3LYP functional and 6-31G(d,p) basis set. The optimized geometry closely resembles the ORTEP. The vibrational patterns present in the molecule are confirmed by FT-IR coinciding with theoretical patterns.

  5. Partitioning of acidic, basic and neutral amino acids into imidazolium-based ionic liquids.

    PubMed

    Absalan, Ghodratollah; Akhond, Morteza; Sheikhian, Leila

    2010-06-01

    In this paper, partitioning behaviors of typical neutral (Alanine), acidic (Glutamic acid) and basic (Lysine) amino acids into imidazolium-based ionic liquids [C(4)mim][PF(6)], [C(6)mim][PF(6)], [C(8)mim][PF(6)], [C(6)mim][BF(4)] and [C(8)mim][BF(4)] as extracting solvents were examined. [C(6)mim][BF(4)] showed the best efficiency for partitioning of amino acids. The partition coefficients of amino acids in ionic liquids were found to depend strongly on pH of the aqueous solution, amino acid and ionic liquid chemical structures. Different chemical forms of amino acids in aqueous solutions were pH dependent, so the pH value of the aqueous phase was a determining factor for extraction of amino acids into ionic liquid phase. Both water content of ionic liquids and charge densities of their anionic and cationic parts were important factors for partitioning of cationic and anionic forms of amino acids into ionic liquid phase. Extracted amino acids were back extracted into phosphate buffer solutions adjusted on appropriate pH values. The results showed that ionic liquids could be used as suitable modifiers on the stationary phase of an HPLC column for efficient separation of acidic, basic, and neutral amino acids.

  6. Electrical conductivity study on micelle formation of long-chain imidazolium ionic liquids in aqueous solution.

    PubMed

    Inoue, Tohru; Ebina, Hayato; Dong, Bin; Zheng, Liqiang

    2007-10-01

    Electrical conductivity was measured for aqueous solutions of long-chain imidazolium ionic liquids (IL), 1-alkyl-3-methylimidazolium bromides with C(12)-C(16) alkyl chains. The break points appeared in specific conductivity (kappa) vs concentration (c) plot indicates that the molecular aggregates, i.e., micelles, are formed in aqueous solutions of these IL species. The critical micelle concentration (cmc) determined from the kappa vs c plot is somewhat lower than those for typical cationic surfactants, alkyltrimethylammonium bromides with the same hydrocarbon chain length. The electrical conductivity data were analyzed according to the mixed electrolyte model of micellar solution, and the aggregation number, n, and the degree of counter ion binding, beta, were estimated. The n values of the present ILs are somewhat smaller than those reported for alkyltrimethylammonium bromides, which may be attributed to bulkiness of the cationic head group of the IL species. The thermodynamic parameters for micelle formation of the present ILs were estimated using the values of cmc and beta as a function of temperature. The contribution of entropy term to the micelle formation is superior to that of enthalpy term below about 30 degrees C, and it becomes opposite at higher temperature. This coincides with the picture drawn for the micelle formation of conventional ionic surfactants.

  7. Study of toxicity of imidazolium ionic liquids to watercress (Lepidium sativum L.).

    PubMed

    Studzińska, Sylwia; Buszewski, Bogusław

    2009-02-01

    The sensitivity of Lepidium sativum L. germination to three imidazolium ionic liquids was investigated in solutions and soils artificially contaminated with mixtures of those compounds. In case of aquatic solutions, the toxic character of analyzed compounds is connected with their hydrophobicity. The seedling growth is increasing with the decrease in ionic liquid hydrophobicity. The novelty of those studies is the application of high-performance liquid chromatography, which was used for the determination of ionic liquid quantity absorbed by cress. There was almost linear relationship between decrease in root germination and amount of ionic liquid uptaken by cress. Furthermore, the systematic studies on the influence of total organic carbon content in soil on the toxicity of ionic liquids to cress were performed for the first time. Hazardous effects appeared to be closely connected with organic matter: with the decrease of total organic carbon quantity, the inhibition of plant growth was more significant. Visual effects of ionic liquid toxic activity to garden cress are similar as in the case of nutrient deficit in plants.

  8. Long alkyl-chain imidazolium ionic liquids: Antibiofilm activity against phototrophic biofilms.

    PubMed

    Reddy, G Kiran Kumar; Nancharaiah, Y V; Venugopalan, V P

    2017-07-01

    Biofilm formation is problematic and hence undesirable in medical and industrial settings. In addition to bacteria, phototrophic organisms are an integral component of biofilms that develop on surfaces immersed in natural waters. 1-Alkyl-3-methyl imidazolium ionic liquids (IL) with varying alkyl chain length were evaluated for their influence on the formation of monospecies (Navicula sp.) and multispecies biofilms under phototrophic conditions. An IL with a long alkyl side chain, 1-hexadecyl-3-methylimidaazolium chloride ([C16(MIM)][Cl]) retarded growth, adhesion and biofilm formation of Navicula sp. at concentrations as low as 5μM. Interestingly, [C16(MIM)][Cl] was very effective in preventing multispecies phototrophic biofilms on fibre reinforced plastic surfaces immersed in natural waters (fresh and seawater). SYTOX(®) Green staining and chlorophyll leakage assay confirmed that the biocidal activity of the IL was exerted through cell membrane disruption. The data show that [C16(MIM)][Cl] is a potent inhibitor of phototrophic biofilms at micromolar concentrations and a promising agent for biofilm control in re-circulating cooling water systems. This is the first report that ionic liquids inhibit biofilm formation by phototrophic organisms which are important members of biofilms in streams and cooling towers. Copyright © 2017 Elsevier B.V. All rights reserved.

  9. Properties of columns with several pyridinium and imidazolium ionic liquid stationary phases.

    PubMed

    Shashkov, M V; Sidelnikov, V N

    2013-09-27

    Recent advances in the development of new liquid phases (ILs) made it possible to use some classes of ILs as polar stationary liquid phases (SLP). In our days only alkylimidazolium- and alkylphosphonium-based ILs are widely used as polar SLP. In present work some other types of ILs - pyridinium and cyanopropyl/hydroxypropyl imidazolium were investigated as SLP. Columns with efficiencies 2000-2500 plates/m by high-pressure static method were prepared. Polarity and selectivity of these phases were measured. Selectivity was described in terms of intermolecular interactions by using Abraham solvatation parameter model. The set of the regularities between cation structure of ionic liquid and selectivity has been shown. The number and position of methyl groups in ionic liquid pyridinium ring were shown to have the sufficient influence on all type of molecular interactions. Finally the resolutions of test mixture for the several ionic liquid SLP were obtained. For columns with some ionic liquids the dependencies of the height equivalent to a theoretical plate (HETP) and sample loading capacity were obtained and compared with the conventional phases. It was found that the optimal efficiency for the IL columns is attained at lower carrier gas velocities in comparison with traditional phases. Nevetheless sample loading capacity of IL phases is comparable to those of conventional GC phases.

  10. The Interactions between Imidazolium-Based Ionic Liquids and Stable Nitroxide Radical Species: A Theoretical Study.

    PubMed

    Zhang, Shaoze; Wang, Guimin; Lu, Yunxiang; Zhu, Weiliang; Peng, Changjun; Liu, Honglai

    2016-08-04

    In this work, the interactions between imidazolium-based ionic liquids and some stable radicals based on 2,2,6,6-tetramethylpiperidine-1-yloxyl (TEMPO) have been systematically investigated using density functional theory calculations at the level of M06-2x. Several different substitutions, such as hydrogen bonding formation substituent (OH) and ionic substituents (N(CH3)3(+) and OSO3(-)), are presented at the 4-position of the spin probe, which leads to additional hydrogen bonds or ionic interactions between these substitutions and ionic liquids. The interactions in the systems of the radicals containing ionic substitutions with ionic liquids are predicted much stronger than those in the systems of neutral radicals, resulting in a significant reduction of the mobility of ionic radicals in ionic liquids. To further understand the nature of these interactions, the natural bond order, atoms in molecules, noncovalent interaction index, electron density difference, energy decomposition analysis, and charge decomposition analysis schemes were employed. The additional ionic interactions between ionic radicals and counterions in ionic liquids are dominantly contributed from the electrostatic term, while the orbital interaction plays a major role in other interactions. The results reported herein are important to understand radical processes in ionic liquids and will be very useful in the design of task-specific ionic liquids to make the processes more efficient.

  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. Interactions of Aqueous Imidazolium-Based Ionic Liquid Mixtures with Solid-Supported Phospholipid Vesicles

    PubMed Central

    Losada-Pérez, Patricia; Khorshid, Mehran; Renner, Frank Uwe

    2016-01-01

    Despite the environmentally friendly reputation of ionic liquids (ILs), their safety has been recently questioned given their potential as cytotoxic agents. The fundamental mechanisms underlying the interactions between ILs and cells are less studied and by far not completely understood. Biomimetic films are here important biophysical model systems to elucidate fundamental aspects and mechanisms relevant for a large range of biological interaction ranging from signaling to drug reception or toxicity. Here we use dissipative quartz crystal microbalance QCM-D to examine the effect of aqueous imidazolium-based ionic liquid mixtures on solid-supported biomimetic membranes. Specifically, we assess in real time the effect of the cation chain length and the anion nature on a supported vesicle layer of the model phospholipid DMPC. Results indicate that interactions are mainly driven by the hydrophobic components of the IL, which significantly distort the layer and promote vesicle rupture. Our analyses evidence the gradual decrease of the main phase transition temperature upon increasing IL concentration, reflecting increased disorder by weakening of lipid chain interactions. The degree of rupture is significant for ILs with long hydrophobic cation chains and large hydrophobic anions whose behavior is reminiscent of that of antimicrobial peptides. PMID:27684947

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

    SciTech Connect

    Zhang, Hongwei; Hong, Kunlun; Mays, Jimmy

    2005-01-01

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

  14. Room-temperature ionic liquids: slow dynamics, viscosity, and the red edge effect.

    PubMed

    Hu, Zhonghan; Margulis, Claudio J

    2007-11-01

    Ionic liquids (ILs) have recently attracted significant attention from academic and industrial sources. This is because, while their vapor pressures are negligible, many of them are liquids at room temperature and can dissolve a wide range of polar and nonpolar organic and inorganic molecules. In this Account, we discuss the progress of our laboratory in understanding the dynamics, spectroscopy, and fluid dynamics of selected imidazolium-based ILs using computational and analytical tools that we have recently developed. Our results indicate that the red edge effect, the non-Newtonian behavior, and the existence of locally heterogeneous environments on a time scale relevant to chemical and photochemical reactivity are closely linked to the viscosity and highly structured character of these liquids.

  15. Wash room, bunkhouse, first floor interior. This room is a ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    Wash room, bunkhouse, first floor interior. This room is a screened porch with the original sinks extant. Light and ventilation was borrowed from the wash room into the toilets and bathing rooms. - Sespe Ranch, Bunkhouse, 2896 Telegraph Road, Fillmore, Ventura County, CA

  16. Staff corridor (room 206, representing rooms 301, 305, 401, 405, ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    Staff corridor (room 206, representing rooms 301, 305, 401, 405, 501, and 505), looking south towards the staff corridor vestibule (room 206A, representing rooms 305A, 405A, and 505A). - California State Office Building No. 1, 915 Capitol Mall, Sacramento, Sacramento County, CA

  17. 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.

  18. Crystal structure of the tetra­gonal polymorph of bis­(1-ethyl-3-methyl­imidazolium) tetra­bromido­cadmate

    PubMed Central

    Đorđević, Tamara; Gerger, Sabrina; Karanović, Ljiljana

    2016-01-01

    Both unique Cd atoms in the tetra­gonal polymorph of bis­(1-ethyl-3-methyl­imidazolium) tetra­bromido­cadmate, (C6H11N2)2[CdBr4], occupy special positions (site symmetry -4). The crystal structure consists of isolated tetra­hedral [CdBr4]2− anions which are surrounded by 1-ethyl-3-methyl­imidazolium cations. The methyl and ethyl side chains of the cations show positional disorder in a 0.590 (11):0.410 (11) ratio. In the crystal, (C6H11N2)+ cations display three weak C—H⋯Br hydrogen-bond inter­actions through the imidazolium ring H atoms with the Br− ligands of the surrounding complex anions. The alkyl groups of the side chains are not involved in hydrogen bonding. PMID:27555953

  19. Ionic Liquid-Derived Imidazolium Cation Linkers for the Layer-by-Layer Assembly of Polyoxometalate-MWCNT Composite Electrodes with High Power Capability.

    PubMed

    Genovese, Matthew; Lian, Keryn

    2016-07-27

    Imidazolium cations derived from ionic liquids were demonstrated as effective linker molecules for the layer-by-layer (LbL) deposition of polyoxometalates (POMs) to increase the charge storage of multi-walled carbon nanotube (MWCNT) electrodes. MWCNTs modified with GeMo12O40(4-) (GeMo12) via an imidazolium cation linker demonstrated highly reversible redox reactions and a capacitance of 84 F cm(-3), close to 4 times larger than bare CNT. Compared to CNT-GeMo12 composites fabricated with a conventional polyelectrolyte linker poly(diallyldimethylammonium chloride), (PDDA), the imidazolium cations resulted in lower POM loading, but higher conductivity and in turn superior performance at fast charge-discharge conditions. A polymerized imidazolium linker (PIL) was also synthesized based on the ethyl-vinyl-imidazolium monomer. CNT-GeMo12 composites fabricated with this PIL achieved high POM loading comparable to PDDA, while still maintaining the good conductivity and high rate capabilities shown by the monomer imidazolium units. The high conductivity imparted by the PIL is especially valuable for the fabrication of multilayer POM composites. Dual-layer GeMo12 O40(4-)-SiMo12O40(4-) (GeMo12-SiMo12) electrodes built with this PIL demonstrated a combined contribution of the individual POMs resulting in a capacitance of 191 F cm(-3), over nine times larger than bare MWCNT. The PIL dual layer composites also maintained 72% of this capacitance at a fast rate of 2 V s(-1), compared to just over 50% retention for similar electrodes fabricated with PDDA.

  20. Computer Room Fire Protection.

    ERIC Educational Resources Information Center

    Price, Bennett J.

    1990-01-01

    Notes that economic and service factors may dictate that special fire protection measures be given to computer rooms. The discussion covers emergency planning, various types of fire detection and suppression systems, and future options, with particular attention to halon and possible halon replacements. A list of suggested readings is provided.…

  1. Romper Room: An Analysis.

    ERIC Educational Resources Information Center

    Barcus, F. Earle

    Video-tape recordings of the Romper Room program carried by TV station WEMT, Bangor, Maine were examined in an attempt to classify and describe various program elements. Tapes were monitored to obtain descriptions of program activities and to focus on some of the commercial announcements. For the total week studied, more than one-third (36%) of…

  2. Visiting Room 501

    ERIC Educational Resources Information Center

    Curwen, Margaret Sauceda

    2009-01-01

    Students in Room 501 were exploring and negotiating their lives as transnational citizens. In a globalized world of instantaneous information and communication, Latino students are shaping, morphing, and evolving into a new generation. This study highlights one group of students who were aspiring toward middle class, which is not the typical…

  3. Locker-Room Talk.

    ERIC Educational Resources Information Center

    Lowe, Jason; Noyes, Brad

    1999-01-01

    Explains how proper athletic facility locker-room design can save time and money. Design factors that address who will be using the facility are discussed as are user requirements, such as preparation areas, total storage area per user, grooming area, and security areas. Final comments address maintenance and operations issues. (GR)

  4. Technology Equipment Rooms.

    ERIC Educational Resources Information Center

    Day, C. William

    2001-01-01

    Examines telecommunications equipment room design features that allow for growth and can accommodate numerous equipment replacements and upgrades with minimal service disruption and with minimal cost. Considerations involving the central hub, power and lighting needs, air conditioning, and fire protection are discussed. (GR)

  5. Rooms with a View

    ERIC Educational Resources Information Center

    Hourihan, Peter; Berry, Millard, III

    2006-01-01

    When well-designed and integrated into a campus living or learning space, an atrium can function as the heart and spirit of a building, connecting interior rooms and public spaces with the outside environment. However, schools and universities should seek technological and HVAC solutions that maximize energy efficiency. This article discusses how…

  6. Rooms with a View

    ERIC Educational Resources Information Center

    Hourihan, Peter; Berry, Millard, III

    2006-01-01

    When well-designed and integrated into a campus living or learning space, an atrium can function as the heart and spirit of a building, connecting interior rooms and public spaces with the outside environment. However, schools and universities should seek technological and HVAC solutions that maximize energy efficiency. This article discusses how…

  7. Technology Equipment Rooms.

    ERIC Educational Resources Information Center

    Day, C. William

    2001-01-01

    Examines telecommunications equipment room design features that allow for growth and can accommodate numerous equipment replacements and upgrades with minimal service disruption and with minimal cost. Considerations involving the central hub, power and lighting needs, air conditioning, and fire protection are discussed. (GR)

  8. Significance of weak interactions in imidazolium picrate ionic liquids: spectroscopic and theoretical studies for molecular level understanding.

    PubMed

    Panja, Sumit Kumar; Dwivedi, Nidhi; Noothalapati, Hemanth; Shigeto, Shinsuke; Sikder, A K; Saha, Abhijit; Sunkari, Sailaja S; Saha, Satyen

    2015-07-21

    The effects of interionic hydrogen bonding and π-π stacking interactions on the physical properties of a new series of picrate anion based ionic liquids (ILs) have been investigated experimentally and theoretically. The existence of aromatic (C2-HO) and aliphatic (C7-HO-N22 and C6-HO-N20) hydrogen bonding and π-π stacking interactions in these ILs has been observed using various spectroscopic techniques. The aromatic and aliphatic C-HO hydrogen bonding interactions are found to have a crucial role in binding the imidazolium cation and picrate anion together. However, the π-π stacking interactions between two successive layers are found to play a decisive role in tight packing in ILs leading to differences in physical properties. The drastic difference in the melting points of the methyl and propyl derivatives (mmimPic and pmimPic respectively) have been found to be primarily due to the difference in the strength and varieties of π-π stacking interactions. While in mmimPic, several different types of π-π stacking interactions between the aromatic rings (such as picrate-picrate, picrate-imidazole and imidazolium-imidazolium cation rings) are observed, only one type of π-π stacking interaction (picrate-picrate rings) is found to exist in the pmimPic IL. NMR spectroscopic studies reveal that the interaction of these ILs with solvent molecules is different and depends on the dielectric constant of the solvent. While an ion solvation model explains the solvation in high dielectric solvents, an ion-pair solvation model is found to be more appropriate for low dielectric constant solvents. The enhanced stability of these investigated picrate ILs compared with that of inorganic picrate salts under high doses of γ radiation clearly indicates the importance of weak interionic interactions in ILs, and also opens up the possibility of the application of picrate ILs as prospective diluents in nuclear separation for advanced fuel cycling process.

  9. Local order and long range correlations in imidazolium halide ionic liquids: a combined molecular dynamics and XAS study.

    PubMed

    Migliorati, Valentina; Serva, Alessandra; Aquilanti, Giuliana; Pascarelli, Sakura; D'Angelo, Paola

    2015-07-07

    A thorough characterization of the structural properties of alkylimidazolium halide ionic liquids (ILs), namely 1-alkyl-3-methylimidazolium bromide ([Cnmim]Br with n = 5, 6, 8, 10) and iodide ([C6mim]I), has been carried out by combining molecular dynamics simulations and EXAFS spectroscopy. The existence of a local order in [Cnmim]Br ILs has been evidenced, with anions and imidazolium head groups forming a local three-dimensional bonding pattern that is common to all the [Cnmim]Br IL family, regardless of the length of the alkyl chain attached to the cation. On the other hand, upon alkyl chain elongation significant differences have been highlighted in the long-range structure of these ILs. Theoretical X-ray structure factors have been calculated from MD simulations and a low q peak has been found for all [Cnmim]Br ILs, indicating the existence of long-range structural correlations. The low q peak moves to smaller q values corresponding to longer distances, increases in intensity and sharpens with increasing alkyl chain length on the cation. Similarities and differences between the ion three-dimensional arrangements in [C6mim]Br and [C6mim]I were highlighted and the structural arrangement of Br(-) and I(-) was found to be different in the proximity of the most acidic hydrogen atom of the imidazolium ring: the I(-) ion is preferentially located above and below the ring plane, while the Br(-) ion has a high probability also to be coplanar with the imidazolium ring. A quantitative analysis of the Br and I K-edge EXAFS spectra of alkylimidazolium halide ILs has been carried out based on the microscopic description of the systems derived from MD simulations. A very good agreement between theoretical and experimental EXAFS signals has been obtained, allowing us to assess the reliability of the MD structural results for all the alkylimidazolium halide ILs investigated in this work.

  10. Bifunctional Imidazolium-Based Ionic Liquid Decorated UiO-67 Type MOF for Selective CO2 Adsorption and Catalytic Property for CO2 Cycloaddition with Epoxides.

    PubMed

    Ding, Luo-Gang; Yao, Bing-Jian; Jiang, Wei-Ling; Li, Jiang-Tao; Fu, Qi-Juan; Li, Yan-An; Liu, Zhen-Hua; Ma, Jian-Ping; Dong, Yu-Bin

    2017-02-20

    A bifunctional robust and highly porous imidazolium-based ionic liquid decorated UiO-67 type MOF (UiO-67-IL, 1) was successfully constructed via solvothermal assembly of the imidazolium-based ligand and Zr(IV) ions. It exhibits a highly selective adsorption for CO2 over CH4 and N2. Furthermore, 1 herein can be used as a highly active heterogeneous catalyst for CO2 cycloaddition with epoxides under atmospheric pressure with or without cocatalyst TBAB (n-Bu4NBr).

  11. Corrosion inhibition performance of imidazolium ionic liquids and their influence on surface ferrous carbonate layer formation

    NASA Astrophysics Data System (ADS)

    Yang, Dongrui

    Corrosion inhibitors as effective anti-corrosion applications were widely studied and drawn much attention in both academe and industrial area. In this work, a systematic work, including inhibitors selection, anti-corrosion property and characterization, influence on scale formation, testing system design and so on, were reported. The corrosion inhibition performance of four imidazolium ionic liquids in carbon dioxide saturated NaCl solution was investigated by using electrochemical and surface analysis technologies. The four compounds are 1-ethyl-3-methylimidazolium chloride (a), 1-butyl-3-methylimidazolium chloride (b), 1-hexyl-3-methylimidazolium chloride (c), 1-decyl-3-methylimidazolium chloride (d). Under the testing conditions, compound d showed the highest inhibition efficiency and selected as the main object of further study. As a selected representative formula, 1-decyl-3-methylimidazolium chloride was studied in detail about its corrosion inhibition performance on mild steel in carbon dioxide saturated NaCl brine at pH 3.8 and 6.8. Electrochemical and surface analysis techniques were used to characterize the specimen corrosion process during the immersion in the blank and inhibiting solutions. The precorrosion of specimen surface showed significant and different influences on the anti-corrosion property of DMICL at pH 3.8 and 6.8. The corrosion inhibition efficiency (IE) was calculated based on parameters obtained from electrochemical techniques; the achieved IE was higher than 98% at the 25th hour for the steel with a well-polished surface at pH 3.8. The fitting parameters obtained from electrochemical data helped to account for the interfacial changes. As proved in previous research, 1-decyl-3-methylimidazolium chloride could be used as good corrosion inhibitors under certain conditions. However, under other conditions, such chemicals, as well as other species in oil transporting system, could be a factor influencing the evolution of protective surface

  12. NMR and Rheological Study of Anion Size Influence on the Properties of Two Imidazolium-based Ionic Liquids.

    PubMed

    Green, Stephen M; Ries, Michael E; Moffat, Jamie; Budtova, Tatiana

    2017-08-21

    NMR self-diffusion and relaxation, coupled with viscosity, were used to study the properties and structure of two imidazolium-based ionic liquids, 1-ethyl-3-methylimidazolium acetate [C2MIM][OAc] and 1-ethyl-3-methylimidazolium octanoate [C2MIM][OOct]. The experimental results point to the formation of different types of aggregates in each ionic liquid. These aggregates are small and stable under flow and temperature in [C2MIM][OAc], whereas the aggregates are large and sensitive to flow and temperature in [C2MIM][OOct]. In the latter case the size of aggregates decreases both under flow and temperature increase.

  13. Design of Phosphonated Imidazolium-Based Ionic Liquids Grafted on γ-Alumina: Potential Model for Hybrid Membranes.

    PubMed

    Pizzoccaro, Marie-Alix; Drobek, Martin; Petit, Eddy; Guerrero, Gilles; Hesemann, Peter; Julbe, Anne

    2016-07-27

    Imidazolium bromide-based ionic liquids bearing phosphonyl groups on the cationic part were synthesized and grafted on γ-alumina (γ-Al₂O₃) powders. These powders were prepared as companion samples of conventional mesoporous γ-alumina membranes, in order to favor a possible transfer of the results to supported membrane materials, which could be used for CO₂ separation applications. Effective grafting was demonstrated using energy dispersive X-ray spectrometry (EDX), N₂ adsorption measurements, fourier transform infrared spectroscopy (FTIR), and special attention was paid to (31)P and (13)C solid state nuclear magnetic resonance spectroscopy (NMR).

  14. Bulk growth, structure, optical properties and laser damage threshold of organic nonlinear optical crystals of Imidazolium L-Ascorbate

    NASA Astrophysics Data System (ADS)

    Saripalli, Ravi Kiran; Bhat, H. L.; Elizabeth, Suja

    2016-09-01

    Bulk, transparent organic nonlinear optical (NLO) single-crystals of imidazolium L-Ascorbate (ImLA) were grown using slow-evaporation. Crystal structure was determined by single crystal X-ray diffraction analysis. Preliminary linear optical measurements through UV-Visible and infrared spectroscopy revealed good optical transmittance and a low near-UV cutoff wavelength at 256 nm. Kurtz and Perry powder test revealed that ImLA is a phase-matchable NLO material with a second harmonic generation (SHG) efficiency of 1.2 times larger than that of standard KH2PO4 (KDP). Laser damage thresholds were determined for ImLA.

  15. An XAFS Study of Niobium chloride in the ionic liquid 1-ethyl-3-methyl imidazolium chloride/ aluminum chloride

    SciTech Connect

    D Roeper; K Pandya; G Cheek; W OGrady

    2011-12-31

    Niobium chloride was studied with extended X-ray absorption fine structure spectroscopy (EXAFS) in acidic and basic aluminum chloride/1-ethyl-3-methyl imidazolium chloride (EMIC) ionic liquids. Although anhydrous Nb2Cl10 is more soluble in the basic melt than in the acidic melt, the EXAFS data shows that the coordination shell around the niobium does not change in the different ionic liquids. Both the acidic and basic melts show a coordination of five chlorides in the first shell. This indicates that in this series of ionic liquids, the Nb2Cl10 breaks up into two NbCl5 entities in both the acidic and the basic melts.

  16. Design of Phosphonated Imidazolium-Based Ionic Liquids Grafted on γ-Alumina: Potential Model for Hybrid Membranes

    PubMed Central

    Pizzoccaro, Marie-Alix; Drobek, Martin; Petit, Eddy; Guerrero, Gilles; Hesemann, Peter; Julbe, Anne

    2016-01-01

    Imidazolium bromide-based ionic liquids bearing phosphonyl groups on the cationic part were synthesized and grafted on γ-alumina (γ-Al2O3) powders. These powders were prepared as companion samples of conventional mesoporous γ-alumina membranes, in order to favor a possible transfer of the results to supported membrane materials, which could be used for CO2 separation applications. Effective grafting was demonstrated using energy dispersive X-ray spectrometry (EDX), N2 adsorption measurements, fourier transform infrared spectroscopy (FTIR), and special attention was paid to 31P and 13C solid state nuclear magnetic resonance spectroscopy (NMR). PMID:27472321

  17. An imidazolium-based polymerized ionic liquid via novel synthetic strategy as polymer electrolytes for lithium ion batteries

    NASA Astrophysics Data System (ADS)

    Yin, Kun; Zhang, Zhengxi; Yang, Li; Hirano, Shin-Ichi

    2014-07-01

    An imidazolium-based polymerized ionic liquid (PIL), poly(1-ethyl-3-vinylimidazolium bis(trifluoromethanesulfonylimide)) is successfully synthesized via a new three-step process comprising the direct radical polymerization of the 1-vinylimidazole monomer, and subsequent quaternization reaction followed by an anion exchange procedure. Furthermore, polymer electrolytes are prepared by blending as-obtained PIL as the polymer host with an ionic liquid and LiTFSI salt. Electrochemical measurements demonstrate that compared with polymer electrolytes containing the PIL host synthesized by the conventional route, polymer electrolytes containing the PIL host obtained by new synthetic process exhibit significantly improved capacity and cycling performance, which is due to higher ionic liquid content.

  18. Four imidazolium iodocuprates based on anion-π and π-π interactions: Structural and spectral modulation

    NASA Astrophysics Data System (ADS)

    Liu, Fang; Hao, Pengfei; Yu, Tanlai; Guan, Qi; Fu, Yunlong

    2016-09-01

    Four imidazolium iodocuprates, [(1,3-dimethylimidazole)(Cu2I3)]n (1), [(1,2,3-trimethylimidazole)(Cu2I3)]n (2), [(1,3-dimethylimidazole)(Cu3I5)]n (3) and [(1,3-dimethylbenzimidazole)(CuI2)]n (4) have been solvothermally synthesized and optically characterized. Results exhibit that cationic spatial orientation, anion-π and π-π interactions are beneficial to structural diversity and band gap modulation of iodocuprate hybrids. The UV-vis diffuse reflectance spectra show that compounds 1-4 are potential semiconductor materials.

  19. Effect of the Methylation and N-H Acidic Group on the Physicochemical Properties of Imidazolium-Based Ionic Liquids.

    PubMed

    Rodrigues, Ana S M C; Rocha, Marisa A A; Almeida, Hugo F D; Neves, Catarina M S S; Lopes-da-Silva, José A; Freire, Mara G; Coutinho, João A P; Santos, Luís M N B F

    2015-07-16

    This work presents and highlights the differentiation of the physicochemical properties of the [C1Him][NTf2], [C2Him][NTf2], [(1)C1(2)C1Him][NTf2], and [(1)C4(2)C1(3)C1im][NTf2] that is related with the strong bulk interaction potential, which highlights the differentiation on the physicochemical arising from the presence of the acidic group (N-H) as well as the methylation in position 2, C(2), of the imidazolium ring. Densities, viscosities, refractive indices, and surface tensions in a wide range of temperatures, as well as isobaric heat capacities at 298.15 K, for this IL series are presented and discussed. It was found that the volumetric properties are barely affected by the geometric and structural isomerization, following a quite regular trend. A linear correlation between the glass transition temperature, Tg, and the alkyl chain size was found; however, ILs with the acidic N-H group present a significant higher Tg than the [(1)CN-1(3)C1im][NTf2] and [(1)CN(3)CNim][NTf2] series. It was found that the most viscous ILs, ([(1)C1Him][NTf2], [(1)C2Him][NTf2], and [(1)C1(2)C1Him][NTf2]) have an acidic N-H group in the imidazolium ring in agreement with the observed increase of energy barrier of flow. The methylation in position 2, C(2), as well as the N-H acidic group in the imidazolium ring contribute to a significant variation in the cation-anion interactions and their dynamics, which is reflected in their charge distribution and polarizability leading to a significant differentiation of the refractive indices, surface tension, and heat capacities. The observed differentiation of the physicochemical properties of the [(1)C1Him][NTf2], [(1)C2Him][NTf2], [(1)C1(2)C1Him][NTf2], and [(1)C4(2)C1(3)C1im][NTf2] are an indication of the stronger bulk interaction potential, which highlights the effect that arises from the presence of the acidic group (N-H) as well as the methylation in position 2 of the imidazolium ring.

  20. Microscopic interactions of the imidazolium-based ionic liquid with molecular liquids depending on their electron-donicity.

    PubMed

    Takamuku, Toshiyuki; Hoke, Hiroshi; Idrissi, Abdenacer; Marekha, Bogdan A; Moreau, Myriam; Honda, Yusuke; Umecky, Tatsuya; Shimomura, Takuya

    2014-11-21

    Microscopic interactions of an imidazolium-based ionic liquid, 1-ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide (C2mimTFSI), with dimethyl sulfoxide (DMSO), methanol (MeOH), and acetonitrile (AN) have been analyzed by means of Raman, attenuated total reflectance infrared (ATR-IR), (1)H and (13)C NMR spectroscopy techniques. The magnitude of the red-shift of the C(2)-H vibration mode of the imidazolium ring and the deshielding of the C(2)-H hydrogen and carbon atoms, compared with that of the other atoms of the ring or the anion, indicated a strong interaction between the C(2)-H hydrogen atom and the molecular liquids in the following order; DMSO ≫ MeOH > AN. This correlates with the order of the electron donicities of these molecular liquids which allows us to suggest a hydrogen bonding character of these interactions. The behavior of S= O vibration of DMSO as a function of the DMSO molar fraction xDMSO also suggested that DMSO molecules are stoichiometrically hydrogen-bonded with the three hydrogen atoms, C(2,4,5)-H, of the ring. In contrast, the hydrogen bonding between MeOH and the C(4,5)-H atoms is much weaker than that in DMSO. AN hardly forms hydrogen bonds with the C(4,5)-H atoms. Instead, AN molecules may interact with the imidazolium ring through the π-π interaction. The interactions between the imidazolium ring and the molecular liquids lead to the loosening of the TFSI anion from the cation; this correlates with both the blue-shift of the S=O stretching vibration of TFSI and the deshielding of the trifluoromethyl carbon atoms with an increase in the molar fraction of the molecular liquid xML. The latter is weak in the MeOH solutions, and may be explained by the possible hydrogen bonding of the MeOH hydroxyl group as an electron-acceptor with the TFSI anion. Furthermore, the organization of MeOH molecules around the ethyl and methyl groups of the cation is discussed in terms of the chemical shift of the hydrogen and carbon atoms in these

  1. Study of the Imidazolium-Based Ionic Liquid - ag Electrified Interface on the CO_{2} Electroreduction by Sum Frequency Spectroscopy.

    NASA Astrophysics Data System (ADS)

    Garcia Rey, Natalia; Dlott, Dana

    2017-06-01

    Imidazolium based ionic liquids (ILs) have been used as a promising system to improve the CO_{2} electroreduction at lower overpotential than other organic or aqueous electrolytes^{1}. Although the detailed mechanism of the CO_{2} electroreduction on Ag has not been elucidated yet, we have developed a methodology to study the electrified interface during the CO_{2} electroreduction using sum frequency generation (SFG) spectroscopy in combination with cyclic voltammetry^{2}. In this work, we tuned the composition of imidazolium-based ILs by exchanging the anion or the functional groups of the imidazolium. We use the nonresonant SFG (NR-SFG) to study the IL-Ag interface and resonant SFG (RES-SFG) to identify the CO adsorbed on the electrode and monitor the Stark shift as a function of cell potential. In previous studies on CO_{2} electroreduction in the IL: 1-ethyl-3-methylimidazolium tetrafluorborate (EMIM-BF_{4}) on Ag, we showed three events occurred at the same potential (-1.33 V vs. Ag/AgCl): the current associated with CO_{2} electroreduction increased, the Stark shift of the adsorbed atop CO doubled in magnitude and the EMIM-BF_{4} underwent a structural transition^{3}. In addition, we also observed how the structural transition of the EMIM-BF_{4} electrolyte shift to lower potentials when the IL is mixed with water. It is known that water enhances the CO_{2} electroreduction producing more CO^{4}. Moreover, the CO is adsorbed in multi-bonded and in atop sites when more water is present in the electrolyte. ^{1}Lau, G. P. S.; Schreier, M.; Vasilyev, D.; Scopelliti, R.; Grätzel, M.; Dyson, P. J., New Insights into the Role of Imidazolium-Based Promoters for the Electroreduction of CO_{2} on a Silver Electrode. J. Am. Chem. Soc. 2016, 138, 7820-7823. ^{2}Garcia Rey, N.; Dlott, D. D., Studies of Electrochemical Interfaces by Broadband Sum Frequency Generation. J. Electroanal. Chem. 2016. DOI:10.1016/j.jelechem.2016.12.023. ^{3}Garcia Rey, N.; Dlott, D. D

  2. Production of 5-hydroxymethylfurfural from corn stalk catalyzed by corn stalk-derived carbonaceous solid acid catalyst.

    PubMed

    Yan, Lulu; Liu, Nian; Wang, Yu; Machida, Hiroshi; Qi, Xinhua

    2014-12-01

    A carbonaceous solid acid was prepared by hydrothermal carbonization of corn stalk followed by sulfonation and was characterized by FT-IR, XRD, SEM and elemental analysis techniques. The as-prepared corn stalk-derived carbonaceous solid acid catalyst contained SO3H, COOH, and phenolic OH groups, and was used for the one-step conversion of intact corn stalk to 5-hydroxymethylfurfural (5-HMF) in the ionic liquid 1-butyl-3-methyl imidazolium chloride ([BMIM][Cl]), where a 5-HMF yield of 44.1% was achieved at 150 °C in 30 min reaction time. The catalytic system was applicable to initial corn stalk concentration of up to ca. 10 wt.% for the production of 5-HMF. The synthesized catalyst and the developed process of using corn stalk-derived carbon catalyst for corn stalk conversion provide a green and efficient strategy for crude biomass utilization.

  3. Black liquor-derived carbonaceous solid acid catalyst for the hydrolysis of pretreated rice straw in ionic liquid.

    PubMed

    Bai, Chenxi; Zhu, Linfeng; Shen, Feng; Qi, Xinhua

    2016-11-01

    Lignin-containing black liquor from pretreatment of rice straw by KOH aqueous solution was applied to prepare a carbonaceous solid acid catalyst, in which KOH played dual roles of extracting lignin from rice straw and developing porosity of the carbon material as an activation agent. The synthesized black liquor-derived carbon material was applied in catalytic hydrolysis of the residue solid from the pretreatment of rice straw, which was mainly composed of cellulose and hemicellulose, and showed excellent activity for the production of total reducing sugars (TRS) in ionic liquid, 1-butyl-3-methyl imidazolium chloride. The highest TRS yield of 63.4% was achieved at 140°C for 120min, which was much higher than that obtained from crude rice straw under the same reaction conditions (36.6% TRS yield). Overall, this study provides a renewable strategy for the utilization of all components of lignocellulosic biomass.

  4. Regenerated cellulose/wool blend enhanced biomimetic hydroxyapatite mineralization.

    PubMed

    Salama, Ahmed; El-Sakhawy, Mohamed

    2016-11-01

    The current article investigates the effect of bioactive cellulose/wool blend on calcium phosphate biomimetic mineralization. Regenerated cellulose/wool blend was prepared by dissolution-regeneration of neat cellulose and natural wool in 1-butyl-3-methyl imidazolium chloride [Bmim][Cl], as a solvent for the two polymers. Crystalline hydroxyapatite nanofibers with a uniform size, shape and dimension were formed after immersing the bioactive blend in simulated body fluid. The cytotoxicity of cellulose/wool/hydroxyapatite was studied using animal fibroblast baby hamster kidney cells (BHK-21) and the result displayed good cytocompatability. This research work presents a green processing method for the development of novel cellulose/wool/hydroxyapatite hybrid materials for tissue engineering applications.

  5. 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.

  6. Aluminium Electrodeposition from Ionic Liquid: Effect of Deposition Temperature and Sonication †

    PubMed Central

    Berretti, Enrico; Giaccherini, Andrea; Martinuzzi, Stefano M.; Innocenti, Massimo; Schubert, Thomas J.S.; Stiemke, Frank M.; Caporali, Stefano

    2016-01-01

    Since their discovery, ionic liquids (ILs) have attracted a wide interest for their potential use as a medium for many chemical processes, in particular electrochemistry. As electrochemical media they allow the electrodeposition of elements that are impossible to reduce in aqueous media. We have investigated the electrodeposition of aluminium from 1-butyl-3-methyl-imidazolium chloride ((Bmim)Cl)/AlCl3 (40/60 mol %) as concerns the effect of deposition parameters on the quality of the deposits. Thick (20 μm) aluminium coatings were electrodeposited on brass substrates at different temperatures and mixing conditions (mechanical stirring and sonication). These coatings were investigated by means of scanning electron microscope, roughness measurements, and X-ray diffraction to assess the morphology and the phase composition. Finally, electrochemical corrosion tests were carried out with the intent to correlate the deposition parameters to the anti-corrosion properties. PMID:28773839

  7. Ionic Liquid Assisted Exfoliation of Layered Magnesium Diboride

    NASA Astrophysics Data System (ADS)

    Ratnam, Devina; Das, Saroj Kumar; Jasuja, Kabeer

    2017-08-01

    The discovery of graphene showcased anability to isolate atomic thin sheet from layered graphite, and presented a precedent to the scientific community for exploring a similar possibility in other layered materials. Magnesium diboride (MgB2), which has metal atoms sandwiched in between boron honeycomb planes, represents an ionic layered material isostructural to intercalated graphite. We show that ultrasonication of MgB2 in ionic liquid (1-butyl-3-methyl imidazolium tetrafluoroborate)results in a stable dispersion of few-layer-thick boron based nanosheets. Furthermore, these nanosheets (∼3-6 µm wide, ∼2 nm thick) are found to exhibit an optical band-gap of ∼3.3eV alongwith excitation wavelength dependent photoluminescence.

  8. 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.

  9. STS-127 Firing Room

    NASA Image and Video Library

    2009-07-11

    NASA mission managers watch the latest weather radar on a monitor in Firing Room Four of the Launch Control Center at NASA's Kennedy Space Center in Cape Canaveral, Florida, Sunday, July 12, 2009. Endeavour is set to launch at 7:13p.m. EDT with the crew of STS-127 and start a 16-day mission that will feature five spacewalks and complete construction of the Japan Aerospace Exploration Agency's Kibo laboratory. Photo Credit: (NASA/Bill Ingalls)

  10. STS-127 Firing Room

    NASA Image and Video Library

    2009-07-11

    NASA Associate Administrator for Space Operations William Gerstenmaier watches the latest weather radar from Firing Room Four of the Launch Control Center at NASA's Kennedy Space Center in Cape Canaveral, Florida, Sunday, July 12, 2009. Endeavour is set to launch at 7:13p.m. EDT with the crew of STS-127 and start a 16-day mission that will feature five spacewalks and complete construction of the Japan Aerospace Exploration Agency's Kibo laboratory. Photo Credit: (NASA/Bill Ingalls)

  11. STS-127 Firing Room

    NASA Image and Video Library

    2009-07-11

    John P. Shannon, Manager, NASA Space Shuttle Program Office watches the latest weather radar in Firing Room Four of the Launch Control Center at NASA's Kennedy Space Center in Cape Canaveral, Florida, Sunday, July 12, 2009. Endeavour is set to launch at 7:13p.m. EDT with the crew of STS-127 and start a 16-day mission that will feature five spacewalks and complete construction of the Japan Aerospace Exploration Agency's Kibo laboratory. Photo Credit: (NASA/Bill Ingalls)

  12. STS-127 Firing Room

    NASA Image and Video Library

    2009-07-11

    NASA Shuttle Launch Director Michael Leinbach talks on the phone from Firing Room Four of the Launch Control Center at NASA's Kennedy Space Center in Cape Canaveral, Florida, Sunday, July 12, 2009. THe space shuttle Endeavour is set to launch at 7:13p.m. EDT with the crew of STS-127 and start a 16-day mission that will feature five spacewalks and complete construction of the Japan Aerospace Exploration Agency's Kibo laboratory. Photo Credit: (NASA/Bill Ingalls)

  13. Clean room wiping cloths

    SciTech Connect

    Harding, W.B.

    1981-01-01

    The suitability of various fabrics for use as clean room wiping cloths was investigated. These fabrics included knit polyester, knit nylon, urethane foam, woven cotton, nonwoven polyester, nonwoven rayon, nonwoven polyethylene and polypropylene, and woven nylon. These materials were tested for detachable lint and fibers, deterioration, and oil content which could leave contaminating films on wiped surfaces. Well-laundered nylon and polyester cloths knitted from filamentary yarn, with hems, were found to be suitable. (LCL)

  14. MACHINE ROOM FROM DOORWAY TO COMMUNICATIONS ROOM, VIEW FACING SOUTHWEST. ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    MACHINE ROOM FROM DOORWAY TO COMMUNICATIONS ROOM, VIEW FACING SOUTHWEST. - Naval Air Station Barbers Point, World War II Command Center, Midway Street east of Lexington Avenue, Ewa, Honolulu County, HI

  15. DETAIL VIEW OF OPERATIONS MANAGEMENT ROOM, FIRING ROOM NO. 4, ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    DETAIL VIEW OF OPERATIONS MANAGEMENT ROOM, FIRING ROOM NO. 4, FACING WEST - Cape Canaveral Air Force Station, Launch Complex 39, Launch Control Center, LCC Road, East of Kennedy Parkway North, Cape Canaveral, Brevard County, FL

  16. DETAIL VIEW OF OPERATIONS MANAGEMENT ROOM, FIRING ROOM NO. 3, ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    DETAIL VIEW OF OPERATIONS MANAGEMENT ROOM, FIRING ROOM NO. 3, FACING EAST - Cape Canaveral Air Force Station, Launch Complex 39, Launch Control Center, LCC Road, East of Kennedy Parkway North, Cape Canaveral, Brevard County, FL

  17. DETAIL VIEW OF OPERATIONS MANAGEMENT ROOM, FIRING ROOM NO. 3, ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    DETAIL VIEW OF OPERATIONS MANAGEMENT ROOM, FIRING ROOM NO. 3, FACING SOUTHEAST - Cape Canaveral Air Force Station, Launch Complex 39, Launch Control Center, LCC Road, East of Kennedy Parkway North, Cape Canaveral, Brevard County, FL

  18. DETAIL VIEW OF OPERATIONS MANAGEMENT ROOM, FIRING ROOM NO. 3, ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    DETAIL VIEW OF OPERATIONS MANAGEMENT ROOM, FIRING ROOM NO. 3, FACING NORTH - Cape Canaveral Air Force Station, Launch Complex 39, Launch Control Center, LCC Road, East of Kennedy Parkway North, Cape Canaveral, Brevard County, FL

  19. INTERIOR VIEW OF A TYPICAL ROOM (ROOM NO. 209), FACING ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    INTERIOR VIEW OF A TYPICAL ROOM (ROOM NO. 209), FACING NORTH. THE SINK AND MIRROR MAY HAVE BEEN FROM THE ORIGINAL CONSTRUCTION. - U.S. Naval Base, Pearl Harbor, Bachelor Officer Quarters, Dealy Circle, Pearl City, Honolulu County, HI

  20. Interior of Room 163, looking northwest in Generator Room ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    Interior of Room 163, looking northwest in Generator Room - Over-the-Horizon Backscatter Radar Network, Bangor Air National Guard Base Operations Building, At the end of Maine Road, Bangor, Penobscot County, ME

  1. Interior of Room 127, looking southsoutheast in Display Controller's Room ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    Interior of Room 127, looking south-southeast in Display Controller's Room - Over-the-Horizon Backscatter Radar Network, Bangor Air National Guard Base Operations Building, At the end of Maine Road, Bangor, Penobscot County, ME

  2. Interior of Room T120, looking northnortheast at pump room ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    Interior of Room T120, looking north-northeast at pump room - Over-the-Horizon Backscatter Radar Network, Moscow Radar Site Transmit Sector One Transmitter Building, At the end of Steam Road, Moscow, Somerset County, ME

  3. Interior of Room 126, looking southsoutheast in Tactical Operations Room ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    Interior of Room 126, looking south-southeast in Tactical Operations Room - Over-the-Horizon Backscatter Radar Network, Bangor Air National Guard Base Operations Building, At the end of Maine Road, Bangor, Penobscot County, ME

  4. View from window of southeast room (bed room no. 1), ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    View from window of southeast room (bed room no. 1), second floor, commandant's house, looking east across parade ground. - Fort Simcoe, Commandant's House & Blockhouse, Fort Simcoe Road, White Swan, Yakima County, WA

  5. 8. GROUND FLOOR, NORTH ROOM, NORTH WALL, VIEW OF ROOM ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    8. GROUND FLOOR, NORTH ROOM, NORTH WALL, VIEW OF ROOM LOOKING TOWARDS FIREPLACE, SHOWING PROJECTING CHIMNEY, WINDOW EMBRASURES ON EITHER SIDE AND PANELING - Ocean Hall, Bushwood, St. Mary's County, MD

  6. 21. Perimeter acquisition radar building room #200, electrical equipment room ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    21. Perimeter acquisition radar building room #200, electrical equipment room - Stanley R. Mickelsen Safeguard Complex, Perimeter Acquisition Radar Building, Limited Access Area, between Limited Access Patrol Road & Service Road A, Nekoma, Cavalier County, ND

  7. 24. Perimeter acquisition radar building room #203, communications room ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    24. Perimeter acquisition radar building room #203, communications room - Stanley R. Mickelsen Safeguard Complex, Perimeter Acquisition Radar Building, Limited Access Area, between Limited Access Patrol Road & Service Road A, Nekoma, Cavalier County, ND

  8. 34. Perimeter acquisition radar building room #325, tape handler room ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    34. Perimeter acquisition radar building room #325, tape handler room - Stanley R. Mickelsen Safeguard Complex, Perimeter Acquisition Radar Building, Limited Access Area, between Limited Access Patrol Road & Service Road A, Nekoma, Cavalier County, ND

  9. 23. Perimeter acquisition radar building room #202, mechanical equipment room ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    23. Perimeter acquisition radar building room #202, mechanical equipment room no. 2 - Stanley R. Mickelsen Safeguard Complex, Perimeter Acquisition Radar Building, Limited Access Area, between Limited Access Patrol Road & Service Road A, Nekoma, Cavalier County, ND

  10. Supreme Court Room (room 573), looking westsouthwest (bearing 250). Not ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    Supreme Court Room (room 573), looking west-southwest (bearing 250). Not that missing scones are to be returned and presently obscured ceiling is proposed for restoration. - California State Library & Courts Building, 914 Capitol Mall, Sacramento, Sacramento County, CA

  11. 7. October 1969 SOUTHWEST ROOM, FIRST FLOOR, 'CAPTAINS' ROOM' (Note: ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    7. October 1969 SOUTHWEST ROOM, FIRST FLOOR, 'CAPTAINS' ROOM' (Note: Furnace has replaced pot-bellied stove, cribbage board on table) - William Rotch Warehouse, Main & South Water Streets, Nantucket, Nantucket County, MA

  12. FACILITY 713, DINING ROOM WITH LIVING ROOM IN LEFT BACKGROUND, ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    FACILITY 713, DINING ROOM WITH LIVING ROOM IN LEFT BACKGROUND, VIEW FACING EAST. - Schofield Barracks Military Reservation, Central-Entry Single-Family Housing Type, Between Bragg & Grime Streets near Ayres Avenue, Wahiawa, Honolulu County, HI

  13. FACILITY 728, LIVING ROOM FROM DINING ROOM, OBLIQUE VIEW FACING ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    FACILITY 728, LIVING ROOM FROM DINING ROOM, OBLIQUE VIEW FACING SOUTH. - Schofield Barracks Military Reservation, Corner-Entry Single-Family Housing Type, Between Bragg & Grime Streets near Williston Avenue, Wahiawa, Honolulu County, HI

  14. FACILITY 809, DINING ROOM WITH LIVING ROOM ON RIGHT, VIEW ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    FACILITY 809, DINING ROOM WITH LIVING ROOM ON RIGHT, VIEW FACING NORTH-NORTHWEST. - Schofield Barracks Military Reservation, Corner-Entry Single-Family Housing Type, Between Hamilton & Tidball Streets, & between Williston & Ayres Avenues, Wahiawa, Honolulu County, HI

  15. 8. VIEW OF ROOM 101 (ASSEMBLY ROOM) FROM NORTHEAST CORNER ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    8. VIEW OF ROOM 101 (ASSEMBLY ROOM) FROM NORTHEAST CORNER SHOWING FLEXIBLE AIR-CONDITIONING DUCT - Vandenberg Air Force Base, Space Launch Complex 3, Vehicle Support Building, Napa & Alden Roads, Lompoc, Santa Barbara County, CA

  16. Interior view, representative groundfloor resident room, looking west. The room ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    Interior view, representative ground-floor resident room, looking west. The room is located on the west side of the south wing. - U. S. Naval Asylum, Biddle Hall, Gray's Ferry Avenue, Philadelphia, Philadelphia County, PA

  17. 175. STORAGE ROOM, SOUTH WALL OF STORAGE ROOM, ADDED WITH ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    175. STORAGE ROOM, SOUTH WALL OF STORAGE ROOM, ADDED WITH ELEVATOR ADDITION OF 1905. WALL IS EXTERIOR OF ORIGINAL WAGON WORKS OF 1883. - Gruber Wagon Works, Pennsylvania Route 183 & State Hill Road at Red Bridge Park, Bernville, Berks County, PA

  18. 44. Launch Control Equipment Room, taken from rear of room. ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    44. Launch Control Equipment Room, taken from rear of room. Lyon - Whiteman Air Force Base, Oscar O-1 Minuteman Missile Alert Facility, Southeast corner of Twelfth & Vendenberg Avenues, Knob Noster, Johnson County, MO

  19. 42. Launch Control Equipment Room, rear of room. Lyon ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    42. Launch Control Equipment Room, rear of room. Lyon - Whiteman Air Force Base, Oscar O-1 Minuteman Missile Alert Facility, Southeast corner of Twelfth & Vendenberg Avenues, Knob Noster, Johnson County, MO

  20. 8. CONTROL AND EQUIPMENT ROOM INTERIOR. MECHANICAL EQUIPMENT ROOM AT ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    8. CONTROL AND EQUIPMENT ROOM INTERIOR. MECHANICAL EQUIPMENT ROOM AT RIGHT AND ENTRANCE AT LEFT. Looking east. - Edwards Air Force Base, South Base Sled Track, Firing Control Blockhouse, South of Sled Track at east end, Lancaster, Los Angeles County, CA

  1. Interior. Storage room for glassware and reference room with frequentlyused ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    Interior. Storage room for glassware and reference room with frequently-used chemistry and chemical engineering texts. - Thomas A. Edison Laboratories, Building No. 2, Main Street & Lakeside Avenue, West Orange, Essex County, NJ

  2. 12. "TAPE ROOM" LOCATED AT SOUTHEAST CORNER OF MAIN ROOM. ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    12. "TAPE ROOM" LOCATED AT SOUTHEAST CORNER OF MAIN ROOM. - Edwards Air Force Base, Air Force Rocket Propulsion Laboratory, Instrumentation & Control Building, Test Area 1-115, northwest end of Saturn Boulevard, Boron, Kern County, CA

  3. Console Room, looking southwesterly into Highbay Generator Room Beale ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    Console Room, looking southwesterly into Highbay Generator Room - Beale Air Force Base, Perimeter Acquisition Vehicle Entry Phased-Array Warning System, Power Plant, End of Spencer Paul Road, north of Warren Shingle Road (14th Street), Marysville, Yuba County, CA

  4. Tribological properties of novel imidazolium ionic liquids bearing benzotriazole group as the antiwear/anticorrosion additive in poly(ethylene glycol) and polyurea grease for steel/steel contacts.

    PubMed

    Cai, Meirong; Liang, Yongmin; Zhou, Feng; Liu, Weimin

    2011-12-01

    The imidazolium ionic liquids (ILs) bearing benzotriazole group were synthesized and evaluated as antiwear (AW) and anticorrosion additive in poly(ethylene glycol) (PEG) and polyurea grease for steel/steel contacts at room temperature and 150 °C. The physical properties of the synthetic ILs and PEG with the additive were measured. The anticorrosion property of the synthetic ILs was assessed via the accelerated corrosion test and copper strip corrosion test, which reveals the excellent anticorrosion properties in comparison with pure PEG and the selected conventional ILs having no benzotriazole group. Tribological results indicated that these ILs as the additives could effectively reduce friction and wear of sliding pairs in PEG and also in polyurea grease. The tribological properties were generally better than the normally used zincdialkyldithiophosphate-based additive package (T204) in polyurea grease. The wear mechanisms are tentatively discussed according to the morphology observation of worn surfaces of steel discs by scanning electron microscope (SEM) and the surface composition analysis by X-ray photoelectron spectroscopy (XPS).

  5. [Virtual room of gastroenterology].

    PubMed

    Spinelli, Osvaldo Mateo; Fittipaldi, Mónica Elsa; Henderson, Eduardo; Krabshuis, Justus Hendrik

    2010-12-01

    The amount of published information and its continuing growth can no longer be managed by an individual searcher. One of today's great challenges for the academic researcher and clinician is to find a relevant scientific article using bibliographic search strategies. We aimed to design and build a Virtual Room of Gastroenterology (VRG) generating real-time automated search strategies and producing bibliographic and full text search results. These results update and complement with the latest evidence the Clinical Guideline Program of the World Gastroenterology Organisation. The HTML driven interface provides a series of pre-formulated MeSH based search strategies for each Aula. For each topic between 10 and 20 specific terms, qualifiers and subheadings are identified. The functionality of the VRG is based on the PubMed's characteristic that allows a search strategy to be captured as a web address. The VRG is available in Spanish and English, and the access is free. There are 28 rooms currently available. All together these rooms provide an advanced bibliographic access using more than 900 pre-programmed MeSH driven strategies. In a further very recent development some of the topics of VRG now allow cascade based searches. These searches look at resource sensitive options and possible ethnic difference per topic. The VRG allows significant reductions in time required to design and carry out complex bibliographic searches in the areas of gastroenterology, hepatology and endoscopy. The system updates automatically in real-time thus ensuring the currency of the results.

  6. Commander's conference room (room 202), closet and hallway to bathroom ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    Commander's conference room (room 202), closet and hallway to bathroom and bedroom, leading to conference room 211. Viewing windows look down on the display area. View to north - March Air Force Base, Strategic Air Command, Combat Operations Center, 5220 Riverside Drive, Moreno Valley, Riverside County, CA

  7. 45. 1915 CLOTH ROOM ADJACENT TO PICKER ROOM, SECOND FLOOR, ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    45. 1915 CLOTH ROOM ADJACENT TO PICKER ROOM, SECOND FLOOR, NORTH END OF MILL NO. 2, WALL ON LEFT DIVIDING CLOTH ROOM ADDED LATER (PROBABLY C. 1970s). - Prattville Manufacturing Company, Number One, 242 South Court Street, Prattville, Autauga County, AL

  8. Room with a View: Ethical Encounters in Room 13

    ERIC Educational Resources Information Center

    Grube, Vicky

    2012-01-01

    In this article, the author describes ethical encounters in Room 13, a schoolroom where children made what they wanted, posed their own questions, and ran an art room like a small business. In Room 13 children had the responsibility to maintain all aspects of the art studio. Specific decisions fell to an annually elected management team, a small…

  9. INTERIOR, FROM DINIG ROOM TO LIVING ROOM AND FRONT LANAI, ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    INTERIOR, FROM DINIG ROOM TO LIVING ROOM AND FRONT LANAI, SHOWING POCKET DOORS BETWEEN LIVING AND DINING ROOMS. VIEW FACING NORTH-NORTHWEST. - U.S. Naval Base, Pearl Harbor, Naval Housing Area Makalapa, Senior Officers' Quarters Type E, 37 Halawa Drive, Pearl City, Honolulu County, HI

  10. The role of hydrogen bonding propensity in tuning the morphology of crystals obtained from imidazolium based ionic liquids

    NASA Astrophysics Data System (ADS)

    Karthika, S.; Radhakrishnan, T. K.; Kalaichelvi, P.

    2017-04-01

    The pharmaceutical crystallization is quite challenging in terms of the target properties like desired habit or morphology, size and the size distribution of the resultant crystals. Controlling the dimensions along the crystallographic axes, especially for the crystals with needle shape, is desired for operational flexibility. There has been a great interest in using Ionic Liquids (ILs) as a novel crystallization media, but inter molecular interaction between ILs and pharmaceutical solids are quite complex. Interactions in ionic media can be tuned to achieve target physical properties. In this study, ibuprofen is crystallized using imidazolium based IL with PF6 anion, which produces needle shaped crystals with high aspect ratio. It is found that aspect ratio is significantly altered when a small quantity of organic solvents is added to the crystallizing media. These organic solvents prefer to interact with certain domain of IL and this interaction can be utilized in achieving the objective of reduction in aspect ratio. Use of methanol and 2-ethoxy ethyl acetate is found to provide a significant reduction in aspect ratio. The role of hydrogen bonding ability of C2 hydrogen of imidazolium ionic liquid in steering the crystal shape is discussed.

  11. Influence of ester functional groups on the liquid-phase structure and solvation properties of imidazolium-based ionic liquids.

    PubMed

    Pensado, Alfonso S; Pádua, Agílio A H; Costa Gomes, Margarida F

    2011-04-14

    The incorporation of ester functions in the side chains in 1-alkyl-3-methylimidazolium cations seems to increase the biodegradability of these ionic liquids. We study here how the presence of ester functional groups affects the liquid-state structure (namely, the microphase segregation between polar and nonpolar domains in these ionic liquids) and the way in which the solvation of gases can be understood in these solvents. We use molecular simulation to study the structure of the ionic liquids 3-methyl-1-(pentoxycarbonylmethyl)imidazolium octylsulfate, [C(1)COOC(5)C(1)im][C(8)SO(4)]; and 3-methyl-1-(pentoxycarbonylmethyl)imidazolium bis(trifluoromethylsulfonyl)imide, [C(1)COOC(5)C(1)im][NTf(2)] in the liquid phase and to assess the molecular mechanisms of solvation of carbon dioxide and ethane. The presence of ester functions influences the relative size of the polar and nonpolar domains in the ionic liquids, but does not significantly affect the solvation of gases.

  12. The Inhibition of Aluminum Corrosion in Sulfuric Acid by Poly(1-vinyl-3-alkyl-imidazolium Hexafluorophosphate).

    PubMed

    Arellanes-Lozada, Paulina; Olivares-Xometl, Octavio; Guzmán-Lucero, Diego; Likhanova, Natalya V; Domínguez-Aguilar, Marco A; Lijanova, Irina V; Arce-Estrada, Elsa

    2014-08-07

    Compounds of poly(ionic liquid)s (PILs), derived from imidazole with different alkylic chain lengths located in the third position of the imidazolium ring (poly(1-vinyl-3-dodecyl-imidazolium) (PImC12), poly(1-vinyl-3-octylimidazolium) (PImC₈) and poly(1-vinyl-3-butylimidazolium) (PImC₄) hexafluorophosphate) were synthesized. These compounds were tested as corrosion inhibitors on aluminum alloy AA6061 in diluted sulfuric acid (0.1-1 M H₂SO₄) by weight loss tests, polarization resistance measurements and inductively coupled plasma optical emission spectroscopy. Langmuir's isotherms suggested film formation on bare alloy while standard free energy indicated inhibition by a physisorption process. However, compound efficiencies as inhibitors ranked low (PImC12 > PImC₈ > PImC₄) to reach 61% for PImC12 in highly diluted acidic solution. Apparently, the high mobility of sulfates favored their adsorption in comparison to PILs. The surface film displayed general corrosion, and pitting occurred as a consequence of PILs' partial inhibition along with a continuous dissolution of defective patchy film on formation. A slight improvement in efficiency was displayed by compounds having high molecular weight and a long alkyl chain, as a consequence of steric hindrance and PIL interactions.

  13. The Inhibition of Aluminum Corrosion in Sulfuric Acid by Poly(1-vinyl-3-alkyl-imidazolium Hexafluorophosphate)

    PubMed Central

    Arellanes-Lozada, Paulina; Olivares-Xometl, Octavio; Guzmán-Lucero, Diego; Likhanova, Natalya V.; Domínguez-Aguilar, Marco A.; Lijanova, Irina V.; Arce-Estrada, Elsa

    2014-01-01

    Compounds of poly(ionic liquid)s (PILs), derived from imidazole with different alkylic chain lengths located in the third position of the imidazolium ring (poly(1-vinyl-3-dodecyl-imidazolium) (PImC12), poly(1-vinyl-3-octylimidazolium) (PImC8) and poly(1-vinyl-3-butylimidazolium) (PImC4) hexafluorophosphate) were synthesized. These compounds were tested as corrosion inhibitors on aluminum alloy AA6061 in diluted sulfuric acid (0.1–1 M H2SO4) by weight loss tests, polarization resistance measurements and inductively coupled plasma optical emission spectroscopy. Langmuir’s isotherms suggested film formation on bare alloy while standard free energy indicated inhibition by a physisorption process. However, compound efficiencies as inhibitors ranked low (PImC12 > PImC8 > PImC4) to reach 61% for PImC12 in highly diluted acidic solution. Apparently, the high mobility of sulfates favored their adsorption in comparison to PILs. The surface film displayed general corrosion, and pitting occurred as a consequence of PILs’ partial inhibition along with a continuous dissolution of defective patchy film on formation. A slight improvement in efficiency was displayed by compounds having high molecular weight and a long alkyl chain, as a consequence of steric hindrance and PIL interactions. PMID:28788156

  14. Characterization of compounds derived from copper-oxamate and imidazolium by X-ray absorption and vibrational spectroscopies

    NASA Astrophysics Data System (ADS)

    do Nascimento, Gustavo M.; do Pim, Walace D.; Reis, Daniella O.; Simões, Tatiana R. G.; Pradie, Noriberto A.; Stumpf, Humberto O.

    2015-05-01

    In this work, compounds derived from copper-oxamate anions (ortho, meta, and para)-phenylenebis (oxamate) and imidazolium cations (1-butyl-3-methylimidazolium) were synthesized. The compounds were characterized by Raman and FTIR spectroscopies and the band assignments were supported by DFT calculations. Strong IR bands from 1610 to 1700 cm-1 dominated the spectra of the complex and can be assigned to νCdbnd O vibrations of the [Cu(opba)]2- anions by the comparison with the DFT data. In opposition to the FTIR spectra, the main vibrational bands in the Raman spectra are observed in the 1350-1600 cm-1 range. All bands in this region are associated to the modified benzene vibrations of the copper-phenylenebis(oxamate) anions. X-ray absorption near edge (XANES) at different energies (NK and Cu L2,3 edges) was also used to probe the interionic interactions. XANES data show that anion-cation interaction in the Cu-oxamate-imidazolium changes the electronic structure around the sbnd Cusbnd Nsbnd sites in the oxamate anion.

  15. The effect of cation structure on the mesophase architecture of self-assembled and polymerized imidazolium-based ionic liquids.

    SciTech Connect

    Batra, D.; Seifert, S.; Firestone, M. A.; Materials Science Division

    2007-01-01

    The binary phase behavior of a series of imidazolium-based ionic liquids (ILs) has been investigated. In particular, the effect of two structural modifications of the imidazolium cation, alkyl chain length, and the introduction of a polymerizable acryloyl group at the alkyl chain terminus, has been studied using small angle X-ray scattering. Upon increasing water content, the non-polymerizable IL, 1-decyl-3-methylimidazolium chloride, adopts mesophase structures of predominately two-dimensional (2D) hexagonal symmetry, including structures intermediate in character between lamellae and 2D hexagonal micelles. Introduction of a photopolymerizable acryloyl functional group to form 1-(10-(acryloyloxy)decyl)-3-methylimidazolium chloride produces a rod-coil IL cation that yields self-assembled mesophases in which the formation of tetragonal morphologies is favored. Covalent linking of the IL cations by UV-induced polymerization converts the lyotropic mesophase into three-dimensional biocontinuous chemical gels. Reducing the alkyl chain length, as in the polymerizable IL cation 1-(8-(acryloyloxy)octyl)-3-methylimidazolium chloride, severely reduces the self-assembled mesophase order, and triggers the formation of only weakly ordered one-dimensional lamellar structures.

  16. Characterization of compounds derived from copper-oxamate and imidazolium by X-ray absorption and vibrational spectroscopies.

    PubMed

    do Nascimento, Gustavo M; do Pim, Walace D; Reis, Daniella O; Simões, Tatiana R G; Pradie, Noriberto A; Stumpf, Humberto O

    2015-05-05

    In this work, compounds derived from copper-oxamate anions (ortho, meta, and para)-phenylenebis (oxamate) and imidazolium cations (1-butyl-3-methylimidazolium) were synthesized. The compounds were characterized by Raman and FTIR spectroscopies and the band assignments were supported by DFT calculations. Strong IR bands from 1610 to 1700cm(-1) dominated the spectra of the complex and can be assigned to νCO vibrations of the [Cu(opba)](2-) anions by the comparison with the DFT data. In opposition to the FTIR spectra, the main vibrational bands in the Raman spectra are observed in the 1350-1600cm(-1) range. All bands in this region are associated to the modified benzene vibrations of the copper-phenylenebis(oxamate) anions. X-ray absorption near edge (XANES) at different energies (NK and Cu L2,3 edges) was also used to probe the interionic interactions. XANES data show that anion-cation interaction in the Cu-oxamate-imidazolium changes the electronic structure around the CuN sites in the oxamate anion.

  17. Fluorescent charge-assisted halogen-bonding macrocyclic halo-imidazolium receptors for anion recognition and sensing in aqueous media.

    PubMed

    Zapata, Fabiola; Caballero, Antonio; White, Nicholas G; Claridge, Tim D W; Costa, Paulo J; Félix, Vítor; Beer, Paul D

    2012-07-18

    The synthesis and anion binding properties of a new family of fluorescent halogen bonding (XB) macrocyclic halo-imidazolium receptors are described. The receptors contain chloro-, bromo-, and iodo-imidazolium motifs incorporated into a cyclic structure using naphthalene spacer groups. The large size of the iodine atom substituents resulted in the isolation of anti and syn conformers of the iodo-imidazoliophane, whereas the chloro- and bromo-imidazoliophane analogues exhibit solution dynamic conformational behavior. The syn iodo-imidazoliophane isomer forms novel dimeric isostructural XB complexes of 2:2 stoichiometry with bromide and iodide anions in the solid state. Solution phase DOSY NMR experiments indicate iodide recognition takes place via cooperative convergent XB-iodide 1:1 stoichiometric binding in aqueous solvent mixtures. (1)H NMR and fluorescence spectroscopic titration experiments with a variety of anions in the competitive CD(3)OD/D(2)O (9:1) aqueous solvent mixture demonstrated the bromo- and syn iodo-imidazoliophane XB receptors to bind selectively iodide and bromide respectively, and sense these halide anions exclusively via a fluorescence response. The protic-, chloro-, and anti iodo-imidazoliophane receptors proved to be ineffectual anion complexants in this aqueous methanolic solvent mixture. Computational DFT and molecular dynamics simulations corroborate the experimental observations that bromo- and syn iodo-imidazoliophane XB receptors form stable cooperative convergent XB associations with bromide and iodide.

  18. Imidazolium embedded C8 based stationary phase for simultaneous reversed-phase/hydrophilic interaction mixed-mode chromatography.

    PubMed

    Qiao, Xiaoqiang; Zhang, Lu; Zhang, Niu; Wang, Xin; Qin, Xinying; Yan, Hongyuan; Liu, Haiyan

    2015-06-26

    A new imidazolium embedded C8 based stationary phase (SIL-MPS-VOL) was facilely prepared by two steps and characterized by Fourier transform infrared spectrometry and thermogravimetric analysis. Due to the introduction of quaternary imidazolium group to the traditional C8 stationary phase, the developed SIL-MPS-VOL column demonstrated both reversed-phase liquid chromatography (RPLC) and hydrophilic interaction liquid chromatography (HILIC) retention mechanisms. A series of hydrophobic and hydrophilic test samples, including benzene homologues, anilines, positional isomers, nucleosides and nucleotides, were used to evaluate the developed SIL-MPS-VOL stationary phase. A rapid separation time, high separation efficiency and planar selectivity were achieved, compared with the commercially available C8 column. Moreover, the developed stationary phase was further used to detect and separate of melamine in powdered infant formula and high polar component of secondary metabolites of Trichoderma, and improved separation efficiency was achieved, indicating the potential merits of the developed SIL-MPS-VOL stationary phase for simultaneous separation of complex hydrophobic and hydrophilic samples with high selectivity.

  19. Coupling dispersive liquid-liquid microextraction to inductively coupled plasma atomic emission spectrometry: An oxymoron?

    PubMed

    Martínez, David; Torregrosa, Daniel; Grindlay, Guillermo; Gras, Luis; Mora, Juan

    2018-01-01

    Coupling dispersive liquid-liquid micro-extraction (DLLME) to inductively coupled plasma atomic emission spectrometry (ICP-AES) is usually troublesome due to the limited plasma tolerance to the organic solvents usually employed for metal extraction. This work explores different coupling strategies allowing the multi-element determination by ICP-AES of the solutions obtained after DLLME procedures. To this end, three of the most common extractant solvents in DLLME procedures (1-undecanol, 1-butyl-3-methyl-imidazolium hexafluorophosphate and chloroform) have been selected to face most of the main problems reported in DLLME-ICP-AES coupling (i.e., those arising from the high solvent viscosity and volatility). Results demonstrate that DLLME can be successfully coupled to ICP-AES after a careful optimization of the experimental conditions. Thus, elemental analysis in 1-undecanol and 1-butyl-3-methyl-imidazolium hexafluorophosphate extracts can be achieved by ICP-AES after a simple dilution step with methanol (1:0.5). Chloroform can be directly introduced into the plasma with minimum changes in the ICP-AES configuration usually employed when operating with aqueous solutions. Diluted inorganic acid solutions (1% w w(-1) either nitric or hydrochloric acids) have been successfully tested for the first time as a carrier for the introduction of organic extractants in ICP-AES. The coupling strategies proposed have been successfully applied to the multi-element analysis (Al, Cu, Fe, Mn, Ni and Zn) of different water samples (i.e. marine, tap and river) by DLLME-ICP-AES. Copyright © 2017 Elsevier B.V. All rights reserved.

  20. One Room Schools in Iowa.

    ERIC Educational Resources Information Center

    Ruth, Amy, Ed.

    1994-01-01

    This issue focuses on one-room school houses in Iowa. At one time, almost 14,000 one-room schools dotted Iowa's rural landscape. Articles explore Native American schools of the past and present, segregation of black students, and Amish schools. An article remembering one-room schools describes the early schools from 1830 to 1858, township schools…

  1. Thermophysical properties of imidazolium tricyanomethanide ionic liquids: experiments and molecular simulation.

    PubMed

    Zubeir, Lawien F; Rocha, Marisa A A; Vergadou, Niki; Weggemans, Wilko M A; Peristeras, Loukas D; Schulz, Peter S; Economou, Ioannis G; Kroon, Maaike C

    2016-08-17

    The low-viscous tricyanomethanide ([TCM](-))-based ionic liquids (ILs) are gaining increasing interest as attractive fluids for a variety of industrial applications. The thermophysical properties (density, viscosity, surface tension, electrical conductivity and self-diffusion coefficient) of the 1-alkyl-3-methylimidazolium tricyanomethanide [Cnmim][TCM] (n = 2, 4 and 6-8) IL series were experimentally measured over the temperature range from 288 to 363 K. Moreover, a classical force field optimized for the imidazolium-based [TCM](-) ILs was used to calculate their thermodynamic, structural and transport properties (density, surface tension, self-diffusion coefficients, viscosity) in the temperature range from 300 to 366 K. The predictions were directly compared against the experimental measurements. The effects of anion and alkyl chain length on the structure and thermophysical properties have been evaluated. In cyano-based ILs, the density decreases with increasing molar mass, in contrast to the behavior of the fluorinated anions, being in agreement with the literature. The contribution per -CH2- group to the increase of the viscosity presents the following sequence: [PF6](-) > [BF4](-) > [Tf2N](-) > [DCA](-) > [TCB](-) > [TCM](-). [TCM](-)-based ILs show lower viscosity than dicyanamide ([DCA](-))- and tetracyanoborate ([TCB](-))-based ILs, while the latter two exhibit a crossover which depends both on temperature and the alkyl chain length of the cation. The surface tension of the investigated ILs decreases with increasing alkyl chain length. [C2mim][TCM] shows an outlier behavior compared to other members of the homologous series. The surface enthalpies and surface entropies for all the studied systems have been calculated based on the experimentally determined surface tensions. The relationship between molar conductivity and viscosity was analyzed using the Walden rule. The experimentally determined self-diffusion coefficients of the cations are in good

  2. Prediction of (1)H NMR chemical shifts for clusters of imidazolium-based ionic liquids.

    PubMed

    Chen, Su; Izgorodina, Ekaterina I

    2017-07-05

    Nuclear magnetic resonance (NMR) has been widely used to elucidate the bulk structure of ionic liquids. In this work, we calculated (1)H NMR chemical shifts of 1-ethyl-3-methylimidazolium (C2mim(+)) ionic liquids combined with various anions such as chloride (Cl), tetrafluoroborate (BF4), hexafluorophosphate (PF6), acetate (OAc), trifluoroacetate (TFA), and dicyanamide (DCA). The previously established level of theory, HF/6-311G+(3df,2p), was used for the accurate prediction of NMR chemical shifts both in gas phase and in solvents with varying dielectric constant such as CHCl3 and ethanol. The following factors affecting the predicted proton chemical shifts were considered. Firstly, ionic clusters consisting of 2, 8 and 16 ion pairs were optimized to model interionic interactions present in the bulk of ionic liquids. In larger clusters the distribution of the calculated chemical shifts of individual protons in the C2mim(+) cation was examined with respect to the position of the cation in the cluster. We further confirmed that electronic properties of ionic liquids such as magnetic shielding had local nature, thus allowing us to accurately predict proton NMR chemical shifts of ionic liquids from relatively small-sized clusters. Secondly, solvent effects in single ion pairs as well as larger ionic clusters were accounted through a Conductor-like Polarisable Continuum Model (CPCM). Solvent effects generated through a dielectric constant of either chloroform or ethanol were found to be important in single ion pairs due to improved description of interionic distances. With increasing cluster size the difference between gas-phase and CPCM optimized structures became minimal, thus resulting in similar values for calculated (1)H NMR chemical shifts. We also established that the model size that produced the best results for imidazolium ionic liquids strongly depended on the anion type. Strongly coordinating anions such as chloride and acetate require calculations of

  3. Sugarcane bagasse pretreatment using three imidazolium-based ionic liquids; mass balances and enzyme kinetics.

    PubMed

    Karatzos, Sergios Kimon; Edye, Leslie Alan; Doherty, William Orlando Sinclair

    2012-08-24

    the three IL studied [C2mim]OAc gave the best saccharification yield, material recovery and delignification. The effects of [C2mim]OAc pretreatment resemble those of aqueous alkali pretreatments while those of [C2mim]Cl and [C4mim]Cl resemble aqueous acid pretreatments. The use of imidazolium IL solvents with shorter alkyl chains results in accelerated dissolution, pretreatment and degradation.

  4. Sugarcane bagasse pretreatment using three imidazolium-based ionic liquids; mass balances and enzyme kinetics

    PubMed Central

    2012-01-01

    in the aqueous IL solution. Of the three IL studied [C2mim]OAc gave the best saccharification yield, material recovery and delignification. The effects of [C2mim]OAc pretreatment resemble those of aqueous alkali pretreatments while those of [C2mim]Cl and [C4mim]Cl resemble aqueous acid pretreatments. The use of imidazolium IL solvents with shorter alkyl chains results in accelerated dissolution, pretreatment and degradation. PMID:22920045

  5. STS-127 Firing Room

    NASA Image and Video Library

    2009-07-11

    NASA Johnson Space Center Director Michael Coats monitors the launch team discussions on his headset from Firing Room Four of the Launch Control Center at NASA's Kennedy Space Center in Cape Canaveral, Florida, Sunday, July 12, 2009. The space shuttle Endeavour is set to launch at 7:13p.m. EDT with the crew of STS-127 and start a 16-day mission that will feature five spacewalks and complete construction of the Japan Aerospace Exploration Agency's Kibo laboratory. Photo Credit: (NASA/Bill Ingalls)

  6. Carbene-anchored/pendent-imidazolium species as precursors to di-N-heterocyclic carbene-bridged mixed-metal complexes.

    PubMed

    Zamora, Matthew T; Ferguson, Michael J; McDonald, Robert; Cowie, Martin

    2009-09-21

    Reaction of a series of linked diimidazolium dibromide salts with one-half equivalent of [Rh(mu-OAc)(COD)](2) under reflux conditions generates a series of carbene-anchored/pendent-imidazolium complexes, [RhBr(COD)((R)C(H)-eta(1)-C(eth))][Br] ((Me)C(H)-eta(1)-C(eth) = ethylene[(N-methyl)imidazolium][(N-methyl)imidazole-2-ylidene] and (tBu)C(H)-eta(1)-C(eth) = ethylene[(N-tert-butyl)imidazolium][(N-tert-butyl)imidazole-2-ylidene]) via deprotonation of one end of the diimidazolium salt and coordination of the resulting carbene to Rh. Reaction of these complexes with carbon monoxide or the appropriate diphosphine yields either [RhBr(CO)(2)((R)C(H)-eta(1)-C(eth))][Br] (R = Me, (t)Bu) or [RhBr(P( intersection)P)((Me)C(H)-eta(1)-C(eth))][Br] (P( intersection)P = Ph(2)PCH(2)PPh(2), Ph(2)PCH(2)CH(2)PPh(2), Et(2)PCH(2)PEt(2)), respectively. The resulting diphosphine complexes readily decompose in solution. A series of palladium complexes [PdI(3-n)(PR(3))(n)(L)][I](n) (n = 1,2) and [PdI(P( intersection)P)(L)][I](2) (L = (tBu)C(H)-eta(1)-C(meth), (tBu)C(H)-eta(1)-C(eth); (tBu)C(H)-eta(1)-C(meth) = methylene[(N-tert-butyl)imidazolium][(N-tert-butyl)imidazole-2-ylidene]), containing the linked NHC-imidazolium moiety, have also been prepared by reacting the triiodo complexes, [PdI(3)((tBu)C(H)-eta(1)-C(meth))] and [PdI(3)((tBu)C(H)-eta(1)-C(eth))] with several mono- and diphosphines. Attempts to generate mixed Rh/Pd complexes using Pd(OAc)(2) to deprotonate the pendent arm of several of the above carbene-anchored/pendent-imidazolium complexes of Rh have proven unsuccessful. However, a targeted di-NHC-bridged heterobimetallic complex [PdI(2)(PEt(3))(mu-(tBu)CC(meth))RhI(COD)] ((tBu) CC(meth) = 1,1'-methylene-3,3'-di-tert-butyldiimidazol-2,2'-diylidene) can be generated by deprotonation of the imidazolium group in [PdI(2)(PEt(3))((tBu)C(H)-eta(1)-C(meth))][I] using half an equivalent of [Rh(mu-OAc)(COD)](2). The X-ray structure determination of this Pd/Rh complex confirms the

  7. Self-assembly of imidazolium-based rodlike ionic liquid crystals: transition from lamellar to micellar organization.

    PubMed

    Cheng, Xiaohong; Bai, Xueqing; Jing, Shan; Ebert, Helgard; Prehm, Marko; Tschierske, Carsten

    2010-04-19

    By using aryl-amination chemistry, a series of rodlike 1-phenyl-1H-imidazole-based liquid crystals (LCs) and related imidazolium-based ionic liquid crystals (ILCs) has been prepared. The number and length of the C-terminal chains (at the noncharged end of the rodlike core) and the length of the N-terminal chain (on the imidazolium unit in the ILCs) were modified and the influence of these structural parameters on the mode of self-assembly in LC phases was investigated by polarizing microscopy, differential scanning calorimetry, and X-ray diffraction. For the single-chain imidazole derivatives nematic phases (N) and bilayer SmA2 phases were found, but upon increasing the number of alkyl chains the LC phases were lost. For the related imidazolium salts LC phases were preserved upon increasing the number and length of the C-terminal chains and in this series it leads to the phase sequence SmA-columnar (Col)-micellar cubic (CubI /Pm3n). Elongation of the N-terminal chain gives the reversed sequence. Short N-terminal chains prefer an end-to-end packing of the mesogens in which these chains are separated from the C-terminal chains. Elongation of the N-terminal chain leads to a mixing of N- and C-terminal chains, which is accompanied by complete intercalation of the aromatic cores. In the smectic phases this gives rise to a transition from bilayer (SmA2) to monolayer smectic (SmA) phases. For the columnar and cubic phases the segregated end-to-end packing leads to core-shell aggregates. In this case, elongation of the N-terminal chains distorts core-shell formation and removes CubI and Col phases in favor of single-layer SmA phases. Hence, by tailoring the length of the N-terminal chain, a crossover from taper-shaped to polycatenar LC tectons was achieved, which provides a powerful tool for control of self-assembly in ILCs.

  8. Dynamics and structure of room temperature ionic liquids

    NASA Astrophysics Data System (ADS)

    Fayer, Michael D.

    2014-11-01

    Room temperature ionic liquids (RTIL) are intrinsically interesting because they simultaneously have properties that are similar to organic liquids and liquid salts. In addition, RTILs are increasingly being considered for and used in technological applications. RTILs are usually composed of an organic cation and an inorganic anion. The organic cation, such as imidazolium, has alkyl chains of various lengths. The disorder in the liquid produced by the presence of the alkyl groups lowers the temperature for crystallization below room temperature and can also result in supercooling and glass formation rather than crystallization. The presence of the alkyl moieties also results in a segregation of the liquid into ionic and organic regions. In this article, experiments are presented that address the relationship between RTIL dynamics and structure. Time resolved fluorescence anisotropy measurements were employed to study the local environments in the organic and ionic regions of RTILs using a nonpolar chromophore that locates in the organic regions and an ionic chromophore that locates in the ionic regions. In the alkyl regions, the in plane and out of plane orientational friction coefficients change in different manners as the alkyl chains get longer. Both friction coefficients converge toward those of a long chain length hydrocarbon as the RTIL chains increase in length, which demonstrates that for sufficiently long alkyl chains the RTIL organic regions have properties similar to a hydrocarbon. However, putting Li+ in the ionic regions changes the friction coefficients in the alkyl regions, which demonstrates that changes of the ion structural organization influences the organization of the alkyl chains. Optical heterodyne detected optical Kerr effect (OHD-OKE) experiments were used to examine the orientational relaxation dynamics of RTILs over times scales of a hundred femtoseconds to a hundred nanoseconds. Detailed temperature dependent studies in the liquid and

  9. CEBAF Control Room Renovation

    SciTech Connect

    Michael Spata; Thomas Oren

    2005-05-01

    The Machine Control Center (MCC) at Jefferson Lab's Continuous Electron Beam Accelerator Facility (CEBAF) was initially constructed in the early 1990s and based on proven technology of that era. Through our experience over the last 15 years and in our planning for the facility's 12 GeV upgrade we reevaluated the control room environment to capitalize on emerging visualization and display technologies and improve workflow processes and ergonomic attributes. This effort also sets the foundation for the redevelopment of the accelerator's control system to deliver high reliability performance with improvements in beam specifications management and information flow. The complete renovation was performed over a three-week maintenance period with no interruption to beam operations. We present the results of this effort.

  10. CEBAF Control Room Renovation

    SciTech Connect

    Michael Spata; Thomas Oren

    2005-05-01

    The Machine Control Center at Jefferson Lab's Continuous Electron Beam Accelerator Facility was initially constructed in the early 1990s and based on proven technology of that era. Through our experience over the last 15 years and in our planning for the facilities 12 GeV upgrade we reevaluated the control room environment to capitalize on emerging visualization and display technologies and improve on workflow processes and ergonomic attributes. This effort also sets the foundation for the redevelopment of the accelerator's control system to deliver high reliability performance with improvements in beam specifications management and information flow. The complete renovation was performed over a three-week period with no interruption to beam operations. We present the results of this effort.

  11. CEBAF Control Room Renovation

    SciTech Connect

    Michael Spata; Anthony Cuffe; Thomas Oren

    2005-03-22

    The Machine Control Center (MCC) at Jefferson Lab's Continuous Electron Beam Accelerator Facility (CEBAF) was constructed in the early 1990s and based on proven technology of that era. Through our experience over the last 15 years and in our planning for the facilities 12 GeV upgrade we reevaluated the control room environment to capitalize on emerging visualization and display technologies and improve on work-flow processes and ergonomic attributes. The renovation was performed in two phases during the summer of 2004, with one phase occurring during machine operations and the latter, more extensive phase, occurring during our semi-annual shutdown period. The new facility takes advantage of advances in display technology, analog and video signal management, server technology, ergonomic workspace design, lighting engineering, acoustic ceilings and raised flooring solutions to provide a marked improvement in the overall environment of machine operations.

  12. Binaural room simulation

    NASA Technical Reports Server (NTRS)

    Lehnert, H.; Blauert, Jens; Pompetzki, W.

    1991-01-01

    In every-day listening the auditory event perceived by a listener is determined not only by the sound signal that a sound emits but also by a variety of environmental parameters. These parameters are the position, orientation and directional characteristics of the sound source, the listener's position and orientation, the geometrical and acoustical properties of surfaces which affect the sound field and the sound propagation properties of the surrounding fluid. A complete set of these parameters can be called an Acoustic Environment. If the auditory event perceived by a listener is manipulated in such a way that the listener is shifted acoustically into a different acoustic environment without moving himself physically, a Virtual Acoustic Environment has been created. Here, we deal with a special technique to set up nearly arbitrary Virtual Acoustic Environments, the Binaural Room Simulation. The purpose of the Binaural Room Simulation is to compute the binaural impulse response related to a virtual acoustic environment taking into account all parameters mentioned above. One possible way to describe a Virtual Acoustic Environment is the concept of the virtual sound sources. Each of the virtual sources emits a certain signal which is correlated but not necessarily identical with the signal emitted by the direct sound source. If source and receiver are non moving, the acoustic environment becomes a linear time-invariant system. Then, the Binaural Impulse Response from the source to a listener' s eardrums contains all relevant auditory information related to the Virtual Acoustic Environment. Listening into the simulated environment can easily be achieved by convolving the Binaural Impulse Response with dry signals and representing the results via headphones.

  13. Phosphoric acid doped polybenzimidazole/imidazolium-modified silsesquioxane hybrid proton conducting membranes for anhydrous proton exchange membrane application

    NASA Astrophysics Data System (ADS)

    Lin, Bencai; Chu, Fuqiang; Yuan, Ningyi; Shang, Hui; Ren, Yurong; Gu, Zongzong; Ding, Jianning; Wei, Yingqiang; Yu, Xiaomin

    2014-04-01

    Phosphoric acid doped polybenzimidazole (PBI)/imidazolium-modified silsesquioxane (Im-SiO3/2) hybrid membranes with high proton conductivity at high temperature under anhydrous conditions are synthesized and characterized. The presence of Im-SiO3/2 is confirmed by FT-IR and energy-dispersive X-ray spectroscopy (EDS) mapping of silicon element. The phosphoric acid uptake and proton conductivity of the hybrid membranes increase with the Im-SiO3/2 content, and the conductivity of PBI/Im-SiO3/2-20 reaching 6.3 × 10-2 S cm-1 at 180 °C. Compared with pure PBI membranes, the introduction of Im-SiO3/2 is effective in preventing the release of the phosphoric acid component from the hybrid membranes. The properties of the prepared hybrid membranes indicate their promising prospects in anhydrous proton exchange membrane applications.

  14. Structural studies of the formation of lipoplexes between siRNA and selected bis-imidazolium gemini surfactants.

    PubMed

    Andrzejewska, W; Pietralik, Z; Skupin, M; Kozak, M

    2016-10-01

    Dicationic (gemini) surfactants are agents that can be used for the preparation of stable complexes of nucleic acids, particularly siRNA for therapeutic purposes. In this study, we demonstrated that bis-imidazolium gemini surfactants with variable lengths of dioxyalkyl linker groups (from dioxyethyl to dioxydodecyl) and dodecyl side chains are excellent for the complexation of siRNA. All of these compounds effectively complexed siRNA in a charge ratio range (p/n) of 1.5-10. The low resolution structure of siRNA oligomers was characterised by small angle scattering of synchrotron radiation (SR-SAXS) and ab initio modelling. The structures of the formed complexes were also analysed using SR-SAXS, circular dichroism studies and electrophoretic mobility tests. The most promising agents for complexation with siRNA were the surfactants that contained dioxyethyl and dioxyhexyl spacer groups. Copyright © 2016 Elsevier B.V. All rights reserved.

  15. Syntheses, characterization and energetic properties of closo-(B12H12)2- salts of imidazolium derivatives.

    PubMed

    Hanumantha Rao, Muddamarri; Muralidharan, Krishnamurthi

    2013-06-28

    The diimidazolium derivative of acetylene and its salt 3,3'-(but-2-yne-1,4-diyl)bis(1-methyl-1H-imidazol-3-ium)chloride (1) was synthesized by a solvent free sonochemical method and then the counter chloride ions were replaced by closo-dodecaborate [(B12H12)(2-)] and perchlorate (ClO4(-)) anions respectively. Along with these two ionic salts, a series of salts with closo-dodecaborate and alkyl imidazolium cations were also synthesized. All the compounds were characterized by NMR and MASS spectral data, elemental analyses and thermogravimetric analyses. In addition to that enthalpy of combustion, enthalpy of formation and heat of explosion of all the compounds were experimentally determined. Based on the properties of these compounds, they can be used as insensitive energetic materials in various fields in propellant research and technology such as solid rocket propellants and burn rate accelerators.

  16. Selenium containing imidazolium salt in designing single source precursors for silver bromide and selenide nano-particles.

    PubMed

    Joshi, Hemant; Sharma, Kamal Nayan; Singh, Ved Vati; Singh, Pradhumn; Singh, Ajai Kumar

    2013-02-21

    The AgBr and Ag(2)Se nanoparticles (NPs) have been synthesized for the first time from two single source precursors ([Ag(2)(L)(2)Br(2)] (1) and [Ag(L-HBr)(2)]BF(4) (2) respectively) designed using the same ligand 3-benzyl-1-(2-phenylselanyl-ethyl)-3H-imidazolium bromide (L). The ODE-ODA-OA (1 : 1 : 2) and TOP-OA (1 : 2) are most suitable solvents for thermolysis of 1 and 2 respectively, resulting in the NPs. The composition of the solvent used in thermolysis affects the purity of NPs. The bonding of L in 1 is unique, as it has a pre-carbene site intact.

  17. Thermophysical and Rheological Properties of Imidazolium-Based Ionic Liquids: The Effect of Aliphatic versus Aromatic Functionality

    NASA Astrophysics Data System (ADS)

    Tao, Ran; Xue, Lianjie; Tamas, George; Quitevis, Edward; Simon, Sindee

    2014-03-01

    As a material class, ionic liquids possess attractive properties and have a wide range of potential uses. In this work, a series of imidazolium-based ionic liquids with the same carbon number varying from aliphatic to aromatic functionalities are investigated. The effects of cation symmetry and larger aromatic polycyclic functionality are studied. The thermal properties, including the glass transition temperature, melting temperature, and decomposition temperature, are characterized, and the density and the ionic conductivity are measured as a function of temperature. Rheological studies are performed using both steady-state and dynamic shear modes. The Cox-Merz relationship between the steady shear viscosity and the dynamic viscosity is examined. The temperature dependence of viscosity is described by the Vogel-Fulcher-Tammann equation and the dynamic fragility is calculated for each ionic liquid and compared to the fragility obtained from calorimetry. Master curves of dynamic shear responses are also constructed and will be discussed.

  18. An XAFS Study of Tantalum Chloride in the Ionic Liquid 1-ethyl-3-methyl Imidazolium Chloride/ aluminum Chloride

    SciTech Connect

    D Roeper; K Pandya; G Cheek; W OGrady

    2011-12-31

    Tantalum chloride was studied with extended X-ray absorption fine structure spectroscopy (XAFS) in acidic and basic aluminum chloride/1-ethyl-3-methyl imidazolium chloride ionic liquids (ILs). Anhydrous Ta2Cl10 is more soluble in the basic solution than in the acidic solution and the X-ray absorption data shows that the coordination shell of chlorides around the tantalum is larger in the basic solution. In the acidic solution, tantalum has five chlorides in its coordination shell while in the basic solution; the tantalum is coordinated by seven chlorides. This indicates that the Lewis acidity of the tantalum chloride causes the Ta to coordinate differently in the acidic and the basic solutions.

  19. Imidazolium-containing, hydrophobic-ionic-hydrophilic ABC triblock copolymers: synthesis, ordered phase-separation, and supported membrane fabrication

    SciTech Connect

    Wiesenauer, EF; Nguyen, PT; Newell, BS; Bailey, TS; Nobleb, RD; Gin, DL

    2013-01-01

    Novel ABC triblock copolymers containing hydrophobic, imidazolium ionic liquid (IL)-based ionic, and non-charged hydrophilic blocks were synthesized by direct sequential, ring-opening metathesis polymerization (ROMP) of three chemically immiscible norborene monomers. The resulting ABC triblock copolymers were found by small-angle X-ray scattering to phase-separate into different nanostructures in their pure melt states, depending on their block sequence and compositions. Supported composite membranes of these triblock copolymers were successfully fabricated with defect-free, <= 20 microns thick top coatings. Preliminary CO2/light gas transport studies demonstrated the potential of this new type of IL-based block copolymer material for gas separation applications.

  20. Bis(1,3-dimethyl-1H-imidazolium) hexa-fluoro-silicate: the second monoclinic polymorph.

    PubMed

    Tian, Chong; Nie, Wanli; Borzov, Maxim V

    2013-01-01

    The title compound, 2C5H9N2 (+)·SiF6 (2-), (I), crystallized as a new polymorph, different from the previously reported one (Ia) [Light et al. (2007 ▶) private communication (refcode: NIQFAV). CCDC, Cambridge, England]. The symmetry [space groups P21/n for (I) and C2/c for(Ia)] and crystal packing patterns are markedly different for this pair of polymorphs. In (I), all imidazolium cations in the lattice are nearly parallel to each other, whereas a herringbone arrangement can be found in (Ia). In (I), each SiF6 (2-) dianion forms four short C-H⋯F contacts with adjacent C5H9N2 (+) cations, resulting in the formation of layers parallel to the ac plane. In (Ia), the C-H⋯F contacts are generally longer and result in the formation of layers along the bc plane.

  1. Synthesis and Biological Evaluation of New Imidazolium and Piperazinium Salts of Pyropheophorbide-a for Photodynamic Cancer Therapy

    PubMed Central

    Sengee, Gerelt-Ireedui; Badraa, Narangerel; Shim, Young Key

    2008-01-01

    We have designed imidazolium and piperazinium salts of pyropheophorbide-a in order to develop effective photosensitizers which have good solubility in polar and non polar media and to reveal the possible influences of the piperazine and imidazole moieties on the biological activities of pyropheophorbide-a. The phototoxicity of those pyropheophorbide-a salts against A549 cells was studied in vitro and compared with that of pyropheophorbide-a. The result showed that complexing piperazine and imidazole into pyropheophorbide-a decreases its dark toxicity without greatly decreasing phototoxicity and, enhances its phototoxicity without greatly increasing dark toxicity, respectively. This work not only describes novel amphiphilic salt complexes of pyropheophobide-a which retain the biological activities of the parent compound pyropheophorbide-a and could be effective candidate for PDT, but also reveals the possibility of developing effective photosensitizers by complexing imidazole and piperazine into other hydrophobic photosensitizers. PMID:19325811

  2. Mechanism of imidazolium ionic liquids toxicity in Saccharomyces cerevisiae and rational engineering of a tolerant, xylose-fermenting strain

    DOE PAGES

    Dickinson, Quinn; Bottoms, Scott; Hinchman, Li; ...

    2016-01-20

    In this study, imidazolium ionic liquids (IILs) underpin promising technologies that generate fermentable sugars from lignocellulose for future biorefineries. However, residual IILs are toxic to fermentative microbes such as Saccharomyces cerevisiae, making IIL-tolerance a key property for strain engineering. To enable rational engineering, we used chemical genomic profiling to understand the effects of IILs on S. cerevisiae. As a result, we found that IILs likely target mitochondria as their chemical genomic profiles closely resembled that of the mitochondrial membrane disrupting agent valinomycin. Further, several deletions of genes encoding mitochondrial proteins exhibited increased sensitivity to IIL. High-throughput chemical proteomics confirmed effectsmore » of IILs on mitochondrial protein levels. IILs induced abnormal mitochondrial morphology, as well as altered polarization of mitochondrial membrane potential similar to valinomycin. Deletion of the putative serine/threonine kinase PTK2 thought to activate the plasma-membrane proton efflux pump Pma1p conferred a significant IIL-fitness advantage. Conversely, overexpression of PMA1 conferred sensitivity to IILs, suggesting that hydrogen ion efflux may be coupled to influx of the toxic imidazolium cation. PTK2 deletion conferred resistance to multiple IILs, including [EMIM]Cl, [BMIM]Cl, and [EMIM]Ac. An engineered, xylose-converting ptk2Δ S. cerevisiae (Y133-IIL) strain consumed glucose and xylose faster and produced more ethanol in the presence of 1 % [BMIM]Cl than the wild-type PTK2 strain. We propose a model of IIL toxicity and resistance. In conclusion, this work demonstrates the utility of chemical genomics-guided biodesign for development of superior microbial biocatalysts for the ever-changing landscape of fermentation inhibitors.« less

  3. Effect of imidazolium-based ionic liquids on the photosynthetic activity and growth rate of Selenastrum capricornutum.

    PubMed

    Pham, Thi Phuong Thuy; Cho, Chul-Woong; Vijayaraghavan, Kuppusamy; Min, Jiho; Yun, Yeoung-Sang

    2008-07-01

    Ionic liquids (ILs) are low-melting organic salts that are being researched intensively as possible environmentally friendly replacements for volatile organic solvents. Despite their nonmeasurable vapor pressure, some quantities of ILs soon will be present in effluent discharges because solubility of ILs in water is small, but far from negligible. Therefore, it is important to understand how ILs will influence aquatic ecosystems. In the present study, the toxic effects of imidazolium-based ILs (1-butyl-3-methylimidazolium cation associated with bromide [BMIM] [Br] and tetrafluoroborate [BMIM] [BF4]) to the freshwater green alga Selenastrum capricornutum were investigated. Two approaches were followed to quantify toxicity of these compounds: Analyses of photosynthetic activity and cell proliferation. The obtained data showed that the relative declines of growth rates generally were more pronounced than those of photosynthetic activity. The ecotoxicity of a range of common organic solvents also was examined. It was revealed that both imidazolium-based ILs studied were some orders of magnitude more toxic than methanol, isopropanol, and dimethylformamide. In addition, with respect to IL incorporating perfluorinated anion, EC50 values (concentrations which lead to a 50% reduction of the exposed organisms relative to control) of the previously prepared stock solution were significantly lower compared to those of the freshly made one. This might be due to hydrolytic effects of [BMIM][BF4] leading to fluoride formation, which was confirmed by ion chromatography analysis. This indicates that, after ILs are discharged into the aqueous system, they can become more toxic than expected by laboratory data with fresh ILs.

  4. Nanostructures in ionic liquids: correlation of iridium nanoparticles' size and shape with imidazolium salts' structural organization and catalytic properties.

    PubMed

    Migowski, Pedro; Zanchet, Daniela; Machado, Giovanna; Gelesky, Marcos A; Teixeira, Sérgio R; Dupont, Jairton

    2010-07-07

    Hydrogen reduction of cationic or neutral Ir(i) compounds, namely [Ir(COD)(2)]BF(4) and [Ir(COD)Cl](2)respectively. in the ionic liquid (IL) 1-alkyl-3-methylimidazolium tetrafluoroborate affords either irregularly sized spherical (from 1.9 +/- 0.4 to 3.6 +/- 0.9 nm) or worm-like metal nanoparticles, depending on the nature of the imidazolium alkyl group and the type of iridium precursor. The ionic Ir(i) precursor tends to be dissolved and concentrated on the IL polar domains (populated by the imidazolium nucleus and tetrafluoroborate anions) while the neutral precursor dissolves preferentially in the non-polar region of the IL (populated mainly by N-alkyl side chains). The size, or volume, of the nano-region where the Ir(i) precursor is dissolved and reduced, determines the size and, probably, the shape of the formed nanoparticles. The HR-TEM image shows that the Ir(0) with worm-like shape are polycrystalline and formed from aggregation individual "spherical" nanoparticles of around 1.9 nm. The catalytic activity of Ir(0) NPs on the hydrogenation of cyclohexene (0.01 mol L(-1) of Ir atoms in IL, 75 degrees C, 8 bar of H(2), 500 rpm stirring, 1/1000 Ir(0)/cyclohexene ratio) is always greater in C(1)C(10)I.BF(4) than C(1)C(4)I.BF(4), regardless of the nature of Ir(i) precursor. Moreover, the cyclohexene hydrogenations performed with Ir(0) nanocatalysts made from ionic Ir(i) precursor are approximately twice faster than those NPs obtained from the neutral Ir(i) precursor, in the same IL.

  5. 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.

  6. Ion-Pair Halogen Bonds in 2-Halo-Functionalized Imidazolium Chloride Receptors: Substituent and Solvent Effects.

    PubMed

    Nunes, Rafael; Costa, Paulo J

    2017-03-02

    The interaction of 2-halo-functionalized imidazolium derivatives (n-X(+) ; X=Cl, Br, I) with a chloride anion through ion-pair halogen bonds (n-X⋅Cl) was studied by means of DFT and ab initio calculations. A method benchmark was performed on 2-bromo-1H-imidazol-3-ium in association with chloride (1-Br⋅Cl); MP2 yielded the best results when compared with CCSD(T) calculations. The interaction energies (ΔE) in the gas phase are high and, although the electrostatic interaction is strong owing to the ion-pair nature of the system, large X⋅⋅⋅Cl(-) Wiberg bond orders and contributions from charge transfer (nCl- →σ*C-X) are obtained. These values drop considerably in chloroform and water; this shows that solvent plays a role in modulating the interaction and that gas-phase calculations are particularly unrealistic for experimental applications. The introduction of electron-withdrawing groups in the 4,5-positions of the imidazolium (e.g., -NO2 , -F) increases the halogen-bond strength in both the gas phase and solvent, including water. The effect of the substituents on the 1,3-positions (N-H groups) also depends on the solvent. The variation of ΔE can be predicted through a two-parameter linear regression that optimizes the weights of charge-transfer and electrostatic interactions, which are different in vacuum and in solvent (chloroform and water). These results could be used in the rational design of efficient chloride receptors based on halogen bonds that work in solution, in particular, in an aqueous environment.

  7. The protonated 2-halogenated imidazolium cation as the noncovalent interaction donor: the σ-hole and π-hole interactions.

    PubMed

    Wang, Jingjing; Mo, Lixin; Li, Xiaoyan; Geng, Zongke; Zeng, Yanli

    2016-12-01

    The σ-hole and π-hole of the protonated 2-halogenated imidazolium cation (XC3H4N2(+); X = F, Cl, Br, I) were investigated and analyzed. The monomers of (CH3)3SiY(Y=F, Cl, Br, I), considered as the Lewis base, were combined with the σ-hole and π-hole of XC3H4N2(+) to form the σ-hole and π-hole interactions in the bimolecular complexes (CH3)3SiY · · · XC3H4N2(+) and (CH3)3SiY · · · C3(X)H4N2(+)(X/Y=F, Cl, Br, I), respectively. For both the σ-hole and π-hole interactions, the equilibrium geometries of complexes show regular changes according to the sequence of heavy sequence of the noncovalent interaction acceptors and donors. The electrostatic energy is the main contribution in the formation of both kinds of interactions, it has linear relations with the V S,max values of σ-hole and the V' S,max values of π-hole. Both the σ-hole and π-hole interactions belong to the closed-shell and noncovalent interactions. The π-hole interactions are stronger than the σ-hole interactions. For the π-hole interactions, the contribution percents of the dispersion energies are somewhat greater than those of the σ-hole interactions, while it is contrary for the polarization energy. Graphical Abstract The protonated 2-halogenated imidazolium cation as the noncovalent interaction donor: the σ-hole and π-hole interactionsᅟ.

  8. Identification and characterization of an imidazolium by-product formed during the synthesis of 4-methylmethcathinone (mephedrone).

    PubMed

    Power, John D; Kavanagh, Pierce; McLaughlin, Gavin; O'Brien, John; Talbot, Brian; Barry, Michael; Twamley, Brendan; Dowling, Geraldine; Brandt, Simon D

    2015-10-01

    4-Methylmethcathinone (2-methylamino-1-(4-methylphenyl)propan-1-one, mephedrone) is a psychoactive substance that has been associated with recreational use worldwide. Analytical data related to mephedrone are abundantly available but the characterization of by-products obtained during organic synthesis remains to be explored. This study presents the identification of a 1,2,3,5-tetramethyl-4-(4-methylphenyl)-1H-imidazol-3-ium salt (TMMPI), which was formed during the synthesis of mephedrone. When diethyl ether was added to the crude reaction product, solid material precipitated from the solution. Analytical characterization of TMMPI employed a range of analytical techniques including chromatographic analysis in combination with various mass spectrometric detection methods, nuclear magnetic resonance spectroscopy, and crystal structure analysis. Additional confirmation was obtained from organic synthesis of the imidazolium by-product. When TMMPI was subjected to analysis by gas chromatography-mass spectrometry (GC-MS), isomerization and degradation into two distinct compounds were observed, which pointed towards thermal instability under GC conditions. A liquid chromatography-mass spectrometry (LC-MS) based investigation into a micro-scale synthesis of mephedrone and three additional analogues revealed that the corresponding TMMPI analogue was formed. Interestingly, storage of mephedrone freebase in a number of organic solvents also gave rise to TMMPI and it appeared that its formation during storage was significantly reduced in the absence of air. The present study aimed to support clandestine forensic investigations by employing analytical strategies that are applicable to manufacturing sites. The imidazolium salts will most likely be found amongst the waste products of any clandestine lab site under investigation rather than with the desired product.

  9. The room acoustic rendering equation.

    PubMed

    Siltanen, Samuel; Lokki, Tapio; Kiminki, Sami; Savioja, Lauri

    2007-09-01

    An integral equation generalizing a variety of known geometrical room acoustics modeling algorithms is presented. The formulation of the room acoustic rendering equation is adopted from computer graphics. Based on the room acoustic rendering equation, an acoustic radiance transfer method, which can handle both diffuse and nondiffuse reflections, is derived. In a case study, the method is used to predict several acoustic parameters of a room model. The results are compared to measured data of the actual room and to the results given by other acoustics prediction software. It is concluded that the method can predict most acoustic parameters reliably and provides results as accurate as current commercial room acoustic prediction software. Although the presented acoustic radiance transfer method relies on geometrical acoustics, it can be extended to model diffraction and transmission through materials in future.

  10. 16. Perimeter acquisition radar building room #102, electrical equipment room; ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    16. Perimeter acquisition radar building room #102, electrical equipment room; the prime power distribution system. Excellent example of endulum-types shock isolation. The grey cabinet and barrel assemble is part of the polychlorinated biphenyl (PCB) retrofill project - Stanley R. Mickelsen Safeguard Complex, Perimeter Acquisition Radar Building, Limited Access Area, between Limited Access Patrol Road & Service Road A, Nekoma, Cavalier County, ND

  11. 37. DINING ROOM FROM BALCONY. THE DINING ROOM ROOF IS ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    37. DINING ROOM FROM BALCONY. THE DINING ROOM ROOF IS SUPPORTED BY A SCISSOR TRUSS SYSTEM REINFORCED WITH TURNBUCKLE IRON RODS AND GUSSET PLATES (NOTE: THIS SYSTEM DIFFERS FROM THE LOBBY). - Old Faithful Inn, 900' northeast of Snowlodge & 1050' west of Old Faithful Lodge, Lake, Teton County, WY

  12. LIVING ROOM WITH THE SLIDING DOORS TO DINING ROOM ON ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    LIVING ROOM WITH THE SLIDING DOORS TO DINING ROOM ON THE LEFT. SHOWING THE WOOD GRILLE TO THE FOYER. VIEW FACING SOUTHEAST - Camp H.M. Smith and Navy Public Works Center Manana Title VII (Capehart) Housing, U-Shaped Two-Bedroom Duplex Type 1, Acacia Road, Birch Circle, and Cedar Drive, Pearl City, Honolulu County, HI

  13. 10. CONTROL ROOM INTERIOR. Looking into southwest corner. CONTROL ROOM ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    10. CONTROL ROOM INTERIOR. Looking into southwest corner. CONTROL ROOM INTERIOR, SHOWING ESCAPE HATCH. Looking north along east wall. - Edwards Air Force Base, Air Force Rocket Propulsion Laboratory, Instrumentation & Control Building, Test Area 1-115, northwest end of Saturn Boulevard, Boron, Kern County, CA

  14. 12. INTERIOR OF LIVING ROOM FROM DINING ROOM SHOWING OPEN ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    12. INTERIOR OF LIVING ROOM FROM DINING ROOM SHOWING OPEN FRONT DOOR AT PHOTO CENTER AND OPEN DOOR TO BEDROOM NO. 1 AT PHOTO LEFT. VIEW TO NORTH. - Bishop Creek Hydroelectric System, Plant 4, Worker Cottage, Bishop Creek, Bishop, Inyo County, CA

  15. 2. ENGINE ROOM AND CHIPPY ENGINE ROOM OF THE DIAMOND ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    2. ENGINE ROOM AND CHIPPY ENGINE ROOM OF THE DIAMOND MINE, LOOKING NORTH. THE MAIN HOIST USED A FLAT CABLE, WHICH WAS SCRAPPED IN THE 1950s. THE ORIGINAL DIXON CABLE STILL EXISTS IN THE CHIPPY HOIST HOUSE. - Butte Mineyards, Diamond Mine, Butte, Silver Bow County, MT

  16. 49. Machinery rooms on north tower. Facing north. Machinery rooms ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    49. Machinery rooms on north tower. Facing north. Machinery rooms contain all motors, motor controllers, and gears for operating one span, in this case, the north span. Note bell with continuous operating clapper for use as fog signals. - Henry Ford Bridge, Spanning Cerritos Channel, Los Angeles-Long Beach Harbor, Los Angeles, Los Angeles County, CA

  17. 35. VIEW OF TELEMETRY ROOM (ROOM 106) FROM ITS NORTHWEST ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    35. VIEW OF TELEMETRY ROOM (ROOM 106) FROM ITS NORTHWEST CORNER SHOWING TM-ISE-3 TELEMETRY CHECKOUT SYSTEM AND HONEYWELL TAPE RECORDER - Vandenberg Air Force Base, Space Launch Complex 3, Launch Operations Building, Napa & Alden Roads, Lompoc, Santa Barbara County, CA

  18. Looking west in the basement utility room, room 24, overview ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    Looking west in the basement utility room, room 24, overview of air handling system, large walk-in filter, large ducts, pipes, and gauges - March Air Force Base, Strategic Air Command, Combat Operations Center, 5220 Riverside Drive, Moreno Valley, Riverside County, CA

  19. From living room through french doors toward room in southeast ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    From living room through french doors toward room in southeast corner of south unit - Fitzsimons General Hospital, Civilian Employees' Quarters, North Hickey Street, West side, 150 feet North of intersection of North Hickey Street & West Loosley Avenue, Aurora, Adams County, CO

  20. 17. Perimeter acquisition radar building room #105, mechanical equipment room ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    17. Perimeter acquisition radar building room #105, mechanical equipment room no. 1; sign reads: Heat exchangers (shell and tube type). Provide precise temperature control of water for cooling critical electronic equipment - Stanley R. Mickelsen Safeguard Complex, Perimeter Acquisition Radar Building, Limited Access Area, between Limited Access Patrol Road & Service Road A, Nekoma, Cavalier County, ND

  1. 16. Bus Room (also known as Switch Gear Room), view ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    16. Bus Room (also known as Switch Gear Room), view to the southeast. An air circuit breaker compressor (visible in photograph number 2) was once attached to the main bus relay visible in the background of the photograph. - Washington Water Power Clark Fork River Cabinet Gorge Hydroelectric Development, Powerhouse, North Bank of Clark Fork River at Cabinet Gorge, Cabinet, Bonner County, ID

  2. Room temperature polyesterification

    SciTech Connect

    Moore, J.S.; Stupp, S.I. . Dept. of Materials Science and Engineering)

    1990-01-01

    A new room temperature polymerization method has been developed for the synthesis of high molecular weight polyesters directly from carboxylic acids and phenols. The solution polymerization reaction proceeds under mild conditions, near neutral pH, and also avoids the use of preactivated acid derivatives for esterification. The reaction is useful in the preparation of isoregic ordered chains with translational polar symmetry and also in the polymerization of functionalized or chiral monomers. The conditions required for polymerization in the carbodiimide-based reaction included catalysis by the 1:1 molecular complex formed by 4-(dimethylamino)pyridine and p-toluenesulfonic acid. These conditions were established through studies on a model system involving esterification of p-toluic acid and p-cresol. Self-condensation of several hydroxy acid monomers by this reaction has produced routinely good yields of polyesters with molecular weights greater than 15,000. It is believed that the high extents of reaction required for significant degrees of polymerization result from suppression of the side reaction leading to N-acylurea. The utility of this reaction in the formation of polar chains from sensitive monomers is demonstrated hereby the polycondensation of a chiral hydroxy acid.

  3. system at room temperature

    NASA Astrophysics Data System (ADS)

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

    2014-04-01

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

  4. Recurarization in the recovery room.

    PubMed

    Albaladejo, P; Kinirons, B; Brocas, E; Benhamou, D; Samii, K

    1999-07-01

    A case of recurarization in the recovery room is reported. Accumulation of atracurium in the intravenous line led to recurarization after flushing the line in the recovery room. A respiratory arrest with severe desaturation and bradycardia occurred. Circumstances leading to this event and the mechanisms enabling a neuromuscular blockade to occur, following the administration of a small dose of relaxant, are discussed.

  5. Children and the Emergency Room

    ERIC Educational Resources Information Center

    Resnick, Rene; Hergenroeder, Elizabeth

    1975-01-01

    Describes a pilot study on emergency room treatment for children 3-13 years of age. The study focuses on children, parents, and their interactions under stress. Results indicate several areas of emergency room care which should be investigated and improved. (ED)

  6. Cytotoxicity towards CCO cells of imidazolium ionic liquids with functionalized side chains: preliminary QSTR modeling using regression and classification based approaches.

    PubMed

    Bubalo, Marina Cvjetko; Radošević, Kristina; Srček, Višnja Gaurina; Das, Rudra Narayan; Popelier, Paul; Roy, Kunal

    2015-02-01

    Within this work we evaluated the cytotoxicity towards the Channel Catfish Ovary (CCO) cell line of some imidazolium-based ionic liquids containing different functionalized and unsaturated side chains. The toxic effects were measured by the reduction of the WST-1 dye after 72 h exposure resulting in dose- and structure-dependent toxicities. The obtained data on cytotoxic effects of 14 different imidazolium ionic liquids in CCO cells, expressed as EC50 values, were used in a preliminary quantitative structure-toxicity relationship (QSTR) study employing regression- and classification-based approaches. The toxicity of ILs towards CCO was chiefly related to the shape and hydrophobicity parameters of cations. A significant influence of the quantum topological molecular similarity descriptor ellipticity (ε) of the imine bond was also observed.

  7. Metallosurfactant Ionogels in Imidazolium and Protic Ionic Liquids as Precursors To Synthesize Nanoceria as Catalase Mimetics for the Catalytic Decomposition of H2 O2.

    PubMed

    Wang, Xiaolin; Yang, Qiao; Cao, Yixue; Hao, Haibin; Zhou, Junhan; Hao, Jingcheng

    2016-12-05

    The gelation behavior of cationic surfactants with different counterions, Br(-) , [FeCl3 Br](-) , and [CeCl3 Br](-) , in imidazolium ionic liquids (ILs) and protic ethylammonium nitrate was investigated. Small-angle X-ray scattering measurements and freeze-fracture transmission electron microscopy observations revealed the lamellar phases of metallosurfactant ionogels. The characteristics of imidazolium ILs, including the size and type, have effects on metallosurfactant ionogel properties, such as transformation temperatures, interlayer spacing, and mechanical strength. Cubic fluorite structured cerium oxide nanoparticles (CeO2 NPs) were produced by using metallosurfactant ionogels as precursors. Cubic fluorite CeO2 exhibited good catalase mimetic activity toward H2 O2 to generate O2 , providing more multiple mimetic enzyme activities of CeO2 NPs for H2 O2 .

  8. Infrared Spectroscopy of Ionic Liquids Consisting of Imidazolium Cations with Different Alkyl Chain Lengths and Various Halogen or Molecular Anions with and Without a Small Amount of Water.

    PubMed

    Yamada, Toshiki; Tominari, Yukihiro; Tanaka, Shukichi; Mizuno, Maya

    2017-03-27

    Infrared spectroscopy was performed on ionic liquids (ILs) that had imidazolium cations with different alkyl chain lengths and various halogen or molecular anions with and without a small amount of water. The molar concentration normalized absorbance due to +C-H vibrational modes in the range of 3000 to 3200 cm-1 was nearly identical for ILs that had imidazolium cations with different alkyl chain lengths and the same anions. A close correlation was found between the red-shifted +C-H vibrational modes, the chemical shift of +C(2)-H proton, and the energy stabilization of hydrogen-bonding interaction. The vibrational modes of the water molecules interacting with anions in the range between 3300 and 3800 cm-1 was examined. The correlation between the vibrational frequencies of water, the frequencies of +C-H vibrational modes, and the center frequency of intermolecular vibrational modes due to ion pairs was discussed.

  9. Imidazolium Sulfonates as Environmental-Friendly Catalytic Systems for the Synthesis of Biologically Active 2-Amino-4H-chromenes: Mechanistic Insights.

    PubMed

    Velasco, Jacinto; Pérez-Mayoral, Elena; Calvino-Casilda, Vanesa; López-Peinado, Antonio J; Bañares, Miguel A; Soriano, Elena

    2015-09-10

    Ionic Liquids (ILs) are valuable reaction media extremely useful in industrial sustainable organic synthesis. We describe here the study on the multicomponent reaction (MCR) between salicylaldehyde (2) and ethyl cyanoacetate (3), catalyzed by imidazolium sulfonates, to form chromenes 1, a class of heterocyclic scaffolds exhibiting relevant biological activity. We have clarified the reaction mechanism by combining the experimental results with computational studies. The results reported herein suggest that both the imidazolium core and the sulfonate anions in the selected ILs are involved in the reaction course acting as hydrogen bond donors and acceptors, respectively. Contrarily to the most widely accepted mechanism through initial Knoevenagel condensation, the most favorable reaction pathway consists of an aldolic reaction between reagents followed by heterocyclization, subsequent dehydration, and, finally, the Michael addition of the second molecule of ethyl cyanoacetate (3) to yield the chromenes 1.

  10. Pairing heterocyclic cations with closo-icosahedral borane and carborane anions. i. benchtop aqueous synthesis of binary triazolium and imidazolium salts with limited water solubility.

    PubMed

    Shackelford, Scott A; Belletire, John L; Boatz, Jerry A; Schneider, Stefan; Wheaton, Amanda K; Wight, Brett A; Hudgens, Leslie M; Ammon, Herman L; Strauss, Steven H

    2009-06-18

    Ten new salts that pair triazolium and imidazolium cations with closo-icosahedral anions [B(12)H(12)](2-) and [CB(11)H(12)](-) were synthesized in water solvent using an open-air, benchtop method. These unreported [Heterocyclium](2)[B(12)H(12)] and [Heterocyclium][CB(11)H(12)] salts extend reports of [Imidazolium][CB(11)H(12)] and [Pyridinium][CB(11)H(12)] salts that were synthesized in anhydrous organic solvents under an inert atmosphere with glovebox or Schlenk techniques. Spectroscopic data, melting points, and densities are reported for each salt. Single-crystal X-ray structures are provided for the five new [B(12)H(12)](2-) salts.

  11. Diverse manganese(II) coordination polymers derived from achiral/chiral imidazolium-carboxylate zwitterions and azide: structure and magnetic properties.

    PubMed

    Wang, Xuan; Li, Xiu-Bing; Yan, Ren-He; Wang, Yan-Qin; Gao, En-Qing

    2013-07-21

    Five Mn(II) coordination polymers containing azide and carboxylate as simultaneous bridges have been derived from different imidazolium-carboxylate zwitterionic ligands: 1-methyl-3-(carboxylatomethyl)imidazolium (L(1)), 1,3-bis(carboxylatomethyl)imidazolium (L(2)), (S,S)-, (R,R)-, and (R,S)-1,3-bis(1-carboxylatoethyl)imidazolium (S,S-L(3), R,R-L(3) and R,S-L(3)). The compounds are formulated as [Mn(L(1))(N3)2] (1), [Mn(L(2))(N3)] (2), [Mn(R,R-L(3))(N3)]·0.5CH3OH (3-R), [Mn(S,S-L(3))(N3)]·0.5CH3OH (3-S), [Mn(R,S-L(3))(N3)] (4). In compound 1, the neutral monocarboxylate zwitterion ligand (L(1)) leads to uniform chains with bis(azide)(carboxylate) bridges. For compounds 2-4, the anionic dicarboxylate zwitterions L(2) and L(3) lead to (azide)bis(carboxylate) bridges, but the overall coordination networks are different. In 2 and 3-S (or 3-R), chains with the (azide)bis(carboxylate) bridges are connected by L(2) and S,S-L(3) (or R,R-L(3)), respectively, to give achiral and chiral 2D coordination networks with different connecting topologies. In compounds 4, which is derived from the mesomeric ligand R,S-L(3), linear trinuclear units with the (azide)bis(carboxylate) bridges are linked by μ-1,3 azides to give 2D layers, and the layers are pillared into a 3D framework by the 1,3-dimethyleneimidazolium tethers. Magnetic analyses suggested that compounds 1-3 behave as 1D antiferromagnetic systems, while 4 shows canted antiferromagnetism with weak ferromagnetic ordering below T(C) = 12.4 K.

  12. Physically Gelled Room-Temperature Ionic Liquid-Based Composite Membranes for CO2/N-2 Separation: Effect of Composition and Thickness on Membrane Properties and Performance

    SciTech Connect

    Nguyen, PT; Voss, BA; Wiesenauer, EF; Gin, DL; Nobe, RD

    2013-07-03

    An aspartame-based, low molecular-weight organic gelator (LMOG) was used to form melt-infused and composite membranes with two different imidazolium-based room-temperature ionic liquids (RTILs) for CO2 separation from N-2. Previous work demonstrated that LMOGs can gel RTILs at low, loading levels, and this aspartame-based LMOG was selected because it has been reported to gel a large number of RTILs. The imidazolium-based RTILs were used because of their inherent good properties for CO2/light gas separations. Analysis of the resulting bulk RTIL/LMOG physical gels showed that these materials have high sol-gel transition temperatures (ca. 135 degrees C) suitable for flue gas applications. Gas permeabilities and burst pressure measurements of thick, melt infused membranes revealed a trade-off between high CO2 permeabilities and good mechanical stability as a function of the LMOG loading. Defect-free, composite membranes of the gelled RTILs were successfully fabricated by choosing an appropriate porous membrane support (hydrophobic PTFE) using a suitable coating technique (roller coating). The thicknesses of the applied composite gel layers ranged from 10.3 to 20.7 mu m, which represents an order of magnitude decrease in active layer thickness, compared to the original melt-infused gel RTIL membranes.

  13. Probing electron density of H-bonding between cation-anion of imidazolium-based ionic liquids with different anions by vibrational spectroscopy.

    PubMed

    Gao, Yan; Zhang, Liqun; Wang, Yong; Li, Haoran

    2010-03-04

    Attenuated total reflection infrared spectroscopy and density functional theory calculation have been employed to study the spectral properties of imidazolium-based ionic liquids (ILs) with different anions. ILs based on 1-butyl-3-methylimidazolium cation with different anions, OH(-), CF(3)CO(2)(-), HSO(4)(-), H(2)PO(4)(-), Cl(-), PF(6)(-), and BF(4)(-), are investigated in the present work. It has been shown that the C(2)-H stretching vibration of the imidazolium ring is closely related to the electron density of H-bonding between the two closest cations and anions for pure ILs. The electron density of H-bonding between cation and anion with different anions decreases in the order [OH](-) > [H(2)PO(4)](-) > [HSO(4)](-) > [CF(3)CO(2)](-) > [Cl](-) > [BF(4)](-) > [PF(6)](-). For aqueous ILs, with increasing water content, the aromatic C-H stretching vibration of the imidazolium cation showed systematic blue-shifts. Especially for BmimOH, the nu(C(2))(-H) undergoes a drastic blue-shift by 58 cm(-1), suggesting that the formation of the strong hydrogen bonds O-H...O may greatly weaken the electron density of H-bonding between the cation and anion of ILs.

  14. Indirect ultraviolet detection of alkaline earth metal ions using an imidazolium ionic liquid as an ultraviolet absorption reagent in ion chromatography.

    PubMed

    Liu, Yong-Qiang; Yu, Hong

    2017-02-20

    A convenient and versatile method was developed for the separation and detection of alkaline earth metal ions by ion chromatography with indirect UV detection. The chromatographic separation of Mg(2+) , Ca(2+) , and Sr(2+) was performed on a carboxylic acid base cation exchange column using imidazolium ionic liquid/acid as the mobile phase, in which the imidazolium ionic liquid acted as an UV-absorption reagent. The effects of imidazolium ionic liquids, detection wavelength, acids in the mobile phase, and column temperature on the retention of Mg(2+) , Ca(2+) , and Sr(2+) were investigated. The main factors influencing the separation and detection were the background UV absorption reagent and the concentration of hydrogen ion in ion chromatography with indirect UV detection. The successful separation and detection of Mg(2+) , Ca(2+) , and Sr(2+) within 14 min were achieved using the selected chromatographic conditions, and the detection limits (S/N = 3) were 0.06, 0.12, and 0.23 mg/L, respectively. A new separation and detection method of alkaline earth metal ions by ion chromatography with indirect UV detection was developed, and the application range of ionic liquids was expanded.

  15. Imidazolium-Based Porous Organic Polymers: Anion Exchange-Driven Capture and Luminescent Probe of Cr2O7(2.).

    PubMed

    Su, Yanqing; Wang, Yangxin; Li, Xiaoju; Li, Xinxiong; Wang, Ruihu

    2016-07-27

    A series of imidazolium-based porous organic polymers (POP-Ims) was synthesized through Yamamoto reaction of 1,3-bis(4-bromophenyl)imidazolium bromide and tetrakis(4-bromophenyl)ethylene. Porosities and hydrophilicity of such polymers may be well tuned by varying the ratios of two monomers. POP-Im with the highest density of imidazolium moiety (POP-Im1) exhibits the best dispersity in water and the highest efficiency in removing Cr2O7(2-). The capture capacity of 171.99 mg g(-1) and the removal efficiency of 87.9% were achieved using an equivalent amount of POP-Im1 within 5 min. However, no Cr2O7(2-) capture was observed using nonionic analogue despite its large surface area and abundant pores, suggesting that anion exchange is the driving force for the removal of Cr2O7(2-). POP-Im1 also displays excellent enrichment ability and remarkable selectivity in capturing Cr2O7(2-). Cr(VI) in acid electroplating wastewater can be removed completely using excess POP-Im1. In addition, POP-Im1 can serve as a luminescent probe for Cr2O7(2-) due to the incorporation of luminescent tetraphenylethene moiety.

  16. DFT Study of the Reaction Mechanisms of Carbon Dioxide and its Isoelectronic Molecules CS2 and OCS Dissolved in Pyrrolidinium and Imidazolium Acetate Ionic Liquids.

    PubMed

    Danten, Y; Cabaço, M I; Coutinho, J A P; Pinaud, Noël; Besnard, M

    2016-06-16

    The reaction mechanisms of CO2 and its isoelectronic molecules OCS and CS2 dissolved in N-butyl-N-methylpyrrolidinium acetate and in 1-butyl-3-methylimidazolium acetate were investigated by DFT calculations in "gas phase". The analysis of predicted multistep pathways allowed calculating energies of reaction and energy barriers of the processes. The major role played by the acetate anion in the degradation of the solutes CS2 and OCS as well as in the capture of OCS and CO2 by the imidazolium ring is highlighted. In both ionic liquids, this anion governs the conversion of CS2 into OCS and of OCS into CO2 through interatomic S-O exchanges between the anion and the solutes with formation of thioacetate anions. In imidazolium acetate, the selective capture of CS2 and OCS by the imidazolium ring competes with the S-O exchanges. From the calculated values of the energy barriers a basicity scale of the anions is proposed. The (13)C NMR chemical shifts of the predicted adducts were calculated and agree well with the experimental observations. It is argued that the scenario issued from the calculated pathways is shown qualitatively to be independent from the functionals and basis set used, constitute a valuable tool in the understanding of chemical reactions taking place in liquid phase.

  17. New Insight into the Formation Mechanism of Imidazolium-Based Ionic Liquids from N-Alkyl Imidazoles and Halogenated Hydrocarbons: A Polar Microenvironment Induced and Autopromoted Process.

    PubMed

    Mu, Xueli; Jiang, Nan; Liu, Chengbu; Zhang, Dongju

    2017-02-09

    To illustrate the formation mechanism of imidazolium-based ionic liquids (ILs) from N-alkyl imidazoles and halogenated hydrocarbons, density functional theory calculations have been carried out on a representative system, the reaction of N-methyl imidazole with chloroethane to form 1-ethyl-3-methyl imidazolium chloride ([Emim]Cl) IL. The reaction is shown to proceed via an SN2 transition state with a free energy barrier of 34.4 kcal/mol in the gas phase and 27.6 kcal/mol in toluene solvent. The reaction can be remarkably promoted by the presence of ionic products and water molecules. The calculated barriers in toluene are 22.0, 21.7, and 19.9 kcal/mol in the presence of 1-3 ionic pairs of [Emim]Cl and 23.5, 21.3, and 19.4 kcal/mol in the presence of 1-3 water molecules, respectively. These ionic pairs and water molecules do not participate directly in the reaction but provide a polar environment that favors stabilizing the transition state with large charge separation. Hence, we propose that the synthesis of imidazolium-based ILs from N-alkyl imidazoles and halogenated hydrocarbons is an autopromoted process and a polar microenvironment induced reaction, and the existence of water molecules (a highly polar solvent) in the reaction may be mainly responsible for the initiation of reaction.

  18. Theoretical Insight into the Conversion Mechanism of Glucose to Fructose Catalyzed by CrCl2 in Imidazolium Chlorine Ionic Liquids.

    PubMed

    Jing, Yaru; Gao, Jun; Liu, Chengbu; Zhang, Dongju

    2017-02-22

    To better understand the efficient transformation of glucose to fructose catalyzed by chromium chlorides in imidazolium-based ionic liquids (ILs), density functional theory calculations have been carried out on a model system which describes the catalytic reaction by CrCl2 in 1,3-dimethylimidazolium chlorine (MMImCl) ionic liquid (IL). The reaction is shown to involve three fundamental processes: ring opening, 1,2-H migration, and ring closure. The reaction is calculated to exergonic by 3.8 kcal/mol with an overall barrier of 37.1 kcal/mol. Throughout all elementary steps, both CrCl2 and MMImCl are found to play substantial roles. The Cr center, as a Lewis acid, coordinates to two hydroxyl group oxygen atoms of glucose to bidentally rivet the substrate, and the imidazolium cation plays a dual role of proton shuttle and H-bond donor due to its intrinsic acidic property, while the Cl(-) anion is identified as a Bronsted/Lewis base and also a H-bond acceptor. Our present calculations emphasize that in the rate-determining step the 1,2-H migration concertedly occurs with the deprotonation of O2-H hydroxyl group, which is in nature different from the stepwise mechanism proposed in the early literature. The present results provide a molecule-level understanding for the isomerization mechanism of glucose to fructose catalyzed by chromium chlorides in imidazolium chlorine ILs.

  19. Solvation Structure of Imidazolium Cation in Mixtures of [C4mim][TFSA] Ionic Liquid and Diglyme by NMR Measurements and MD Simulations.

    PubMed

    Shimomura, Takuya; Kodama, Daisuke; Kanakubo, Mitsuhiro; Tsuzuki, Seiji

    2017-04-06

    Interactions of 1-butyl-3-methylimidazolium cation ([C4mim](+)) with bis(trifluoromethanesulfonyl)amide anion ([TFSA](-)) and diethyleneglycol dimethyl ether (diglyme) in mixtures of [C4mim][TFSA] ionic liquid and diglyme have been investigated using (1)H and (13)C NMR spectroscopy and molecular dynamics (MD) simulations. The results of NMR chemical shift measurements and MD simulations showed that the diglyme oxygen atoms have contact with the imidazolium hydrogen atoms of [C4mim](+) in the mixtures. The contact between the hydrogen atoms of imidazolium and the oxygen atoms of [TFSA](-) remains even when the diglyme mole fraction (xdiglyme) increases up to 0.9. However, the coordination numbers of the hydrogen atoms of [C4mim](+) with oxygen atoms of diglyme increase with xdiglyme. The [TFSA](-) anions around [C4mim](+) are not completely replaced by diglyme even at xdiglyme > 0.9. The MD simulations revealed that the diglymes also have contact with the butyl group of [C4mim](+). The methyl groups of diglyme prefer to have contact with the terminal methyl group of the butyl group, whereas the diglyme oxygen atoms prefer to have contact with the methylene group connected to the imidazolium ring of [C4mim](+).

  20. Crystal structure, vibrational and magnetic properties of the monohydrated cobalt (II) complex with 1-(4-Nitrophenyl)-1H-imidazolium cation, (C9H8N3O2)2CoCl4·H2O

    NASA Astrophysics Data System (ADS)

    Amamou, W.; Chniba-Boudjada, N.; Zouari, F.

    2017-01-01

    Single crystals of organic-inorganic hybrid compound Bis(1-(4-Nitrophenyl)-1H-imidazolium) tetrachlorocobaltate monohydrate, was obtained by slow evaporation of an aqueous solution at room temperature and characterized by a single-crystal X-ray diffraction, an elemental and thermal analysis, UV-Vis spectra, FT-IR and FT-Raman spectroscopies as well as magnetic measurements. The entitled compound crystallizes into triclinic system of P-1 space group. The Co(II) ion of the [CoCl4]2- anion shows a tetrahedral coordinating geometry. The atomic arrangement can be described as an alternation of organic and inorganic layers along the c-axis. The different components are connected by Nsbnd H⋯Cl, Osbnd H⋯Cl and Osbnd H⋯O hydrogen bonds. The differential scanning calorimetry (DSC) of the title compound revealed an endothermic peak at 52 °C related with a phase transformation caused by a slight deformation of the inorganic group. The room temperature IR and Raman spectra were recorded and analyzed on the basis of literary data to gain more information about the entitled compound. The magnetic susceptibility measurements in the temperature range 2-100 K shows that the complex displays a weak antiferromagnetic exchange interaction at very low temperatures.

  1. 33. ROOM A (WEST ROOM) LOOKING SOUTHWEST. The windows above ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    33. ROOM A (WEST ROOM) LOOKING SOUTHWEST. The windows above the original Ministers' Gallery were raised in 1888 when inside toilet facilities were added on the other side of the west wall. Note the sloped window sills which provided more light. Also at the rear of the Meeting House a caretaker's apartment was added in 1908. - Twelfth Street Meeting House, 20 South Twelfth Street, Philadelphia, Philadelphia County, PA

  2. Solution processable semiconductor thin films: Correlation between morphological, structural, optical and charge transport properties

    NASA Astrophysics Data System (ADS)

    Isik, Dilek

    strategies for low power consuming solution based electronics and capitalizing on the expertise of the group in the synthesis of solution deposited WO3 films the electrolyte gating approach was explored in ARTICLE 3. Ionic liquids, that are molten salts at room temperature, were employed as the electrolyte. Ionic liquids are attractive for their low volatility, non-flammability, ionic conductivity and thermal and electrochemical stability. Thin films of WO3 were deposited onto pre-patterned ITO substrates (source-drain interelectrode distance, 1 mm) prepared by wet chemical etching. SEM and AFM showed an interconnected film nanostructure. Electrolyte gated WO3 thin film transistors making use of 1-butyl-3-methyl imidazolium bis(trifluoromethylsulfonyl)imide ([BMIM][TFSI]), 1-butyl-3-methyl imidazolium hexafluoro phosphate ([BMIM][PF6]), and 1-ethyl-3-methyl imidazolium bis(trifluoromethylsulfonyl)imide ([EMIM][TFSI]) showed an n-type transistor behavior. The possibility to obtain WO3 electrolyte gated transistors represents an opportunity to fabricate electronic devices working at relatively low operating voltages (about 1 V) by using simple fabrication techniques.

  3. Operating room design and its impact on operating room economics.

    PubMed

    Krupka, Dan C; Sandberg, Warren S

    2006-04-01

    Operating rooms are high-cost/high-revenue environments. In an era of rising costs and declining reimbursement, it is essential to optimize the effectiveness of the operating room suite, maximizing throughput of profitable cases while minimizing the costs of necessary, but unprofitable, procedures. Operating room management focuses on reducing wasted time in order to perform more cases in regular business hours, reduce overtime, or provide a better experience for staff and patients. It has been difficult to improve perioperative efficiency enough to reliably add cases during regular hours because the required time savings are so large, while most interventions can save only a few minutes per case. Recent work, however, has changed the basic paradigms for turning over operating rooms, dramatically reducing nonproductive time and increasing operating room throughput. In some situations, the additional expense required to achieve throughput improvements is more than offset by financial gains. Redesigning perioperative systems can increase operating room throughput, but not all case mixes benefit from the required additional resources. Thus hospitals should choose judiciously if, and to what degree, high throughput environments are implemented. Once implemented, access to these environments can be used as an incentive for improved surgical performance.

  4. 32 CFR 518.9 - Reading room.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 32 National Defense 3 2013-07-01 2013-07-01 false Reading room. 518.9 Section 518.9 National... RELATIONS THE FREEDOM OF INFORMATION ACT PROGRAM FOIA Reading Rooms § 518.9 Reading room. (a) Reading room... the records described, DA may elect to place other records in their reading room, and also make...

  5. 32 CFR 518.9 - Reading room.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 32 National Defense 3 2011-07-01 2009-07-01 true Reading room. 518.9 Section 518.9 National... RELATIONS THE FREEDOM OF INFORMATION ACT PROGRAM FOIA Reading Rooms § 518.9 Reading room. (a) Reading room... the records described, DA may elect to place other records in their reading room, and also make...

  6. What's New in Locker Rooms?

    ERIC Educational Resources Information Center

    Rittner-Heir, Robbin M.

    2001-01-01

    Discusses athletic facility design and renovation issues that exist because of increasing numbers of female athletes. Outlines renovation issues such as locker room facilities, space for sports equipment, and additional athletic fields. (GR)

  7. Nuclear reactor control room construction

    DOEpatents

    Lamuro, Robert C.; Orr, Richard

    1993-01-01

    A control room 10 for a nuclear plant is disclosed. In the control room, objects 12, 20, 22, 26, 30 are no less than four inches from walls 10.2. A ceiling 32 contains cooling fins 35 that extend downwards toward the floor from metal plates 34. A concrete slab 33 is poured over the plates. Studs 36 are welded to the plates and are encased in the concrete.

  8. Nuclear reactor control room construction

    DOEpatents

    Lamuro, R.C.; Orr, R.

    1993-11-16

    A control room for a nuclear plant is disclosed. In the control room, objects labelled 12, 20, 22, 26, 30 in the drawing are no less than four inches from walls labelled 10.2. A ceiling contains cooling fins that extend downwards toward the floor from metal plates. A concrete slab is poured over the plates. Studs are welded to the plates and are encased in the concrete. 6 figures.

  9. Influence of Reactive Oxygen Species on the Enzyme Stability and Activity in the Presence of Ionic Liquids

    PubMed Central

    Attri, Pankaj; Choi, Eun Ha

    2013-01-01

    In this paper, we have examined the effect of ammonium and imidazolium based ionic liquids (ILs) on the stability and activity of proteolytic enzyme α-chymotrypsin (CT) in the presence of cold atmospheric pressure plasma jet (APPJ). The present work aims to illustrate the state of art implementing the combined action of ILs and APPJ on the enzyme stability and activity. Our circular dichroism (CD), fluorescence and enzyme activity results of CT have revealed that buffer and all studied ILs {triethylammonium hydrogen sulphate (TEAS) from ammonium family and 1-butyl-3-methyl imidazolium chloride ([Bmim][Cl]), 1-methylimidazolium chloride ([Mim][Cl]) from imidazolium family} are notable to act as protective agents against the deleterious action of the APPJ, except triethylammonium dihydrogen phosphate (TEAP) ammonium IL. However, TEAP attenuates strongly the deleterious action of reactive oxygen species (ROS) created by APPJ on native structure of CT. Further, TEAP is able to retain the enzymatic activity after APPJ exposure which is absent in all the other systems.This study provides the first combined effect of APPJ and ILs on biomolecules that may generate many theoretical and experimental opportunities. Through this methodology, we can utilise both enzyme and plasma simultaneously without affecting the enzyme structure and activity on the material surface; which can prove to be applicable in various fields. PMID:24066167

  10. Gutmann's Donor Numbers Correctly Assess the Effect of the Solvent on the Kinetics of SN Ar Reactions in Ionic Liquids.

    PubMed

    Alarcón-Espósito, Jazmín; Contreras, Renato; Tapia, Ricardo A; Campodónico, Paola R

    2016-09-05

    We report an experimental study on the effect of solvents on the model SN Ar reaction between 1-chloro-2,4-dinitrobenzene and morpholine in a series of pure ionic liquids (IL). A significant catalytic effect is observed with reference to the same reaction run in water, acetonitrile, and other conventional solvents. The series of IL considered include the anions, NTf2 (-) , DCN(-) , SCN(-) , CF3 SO3 (-) , PF6 (-) , and FAP(-) with the series of cations 1-butyl-3-methyl-imidazolium ([BMIM](+) ), 1-ethyl-3-methyl-imidazolium ([EMIM](+) ), 1-butyl-2,3-dimethyl-imidazolium ([BM2 IM](+) ), and 1-butyl-1-methyl-pyrrolidinium ([BMPyr](+) ). The observed solvent effects can be attributed to an "anion effect". The anion effect appears related to the anion size (polarizability) and their hydrogen-bonding (HB) abilities to the substrate. These results have been confirmed by performing a comparison of the rate constants with Gutmann's donicity numbers (DNs). The good correlation between rate constants and DN emphasizes the major role of charge transfer from the anion to the substrate. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  11. Isolation of a C5-Deprotonated Imidazolium, a Crystalline “Abnormal” N-Heterocyclic Carbene

    PubMed Central

    Aldeco-Perez, Eugenia; Rosenthal, Amos J.; Donnadieu, Bruno; Parameswaran, Pattiyil; Frenking, Gernot; Bertrand, Guy

    2010-01-01

    The discovery two decades ago of metal-free stable carbenes, especially imidazol-2-ylidenes [N-heterocyclic carbenes (NHCs)], has led to numerous breakthroughs in organic and organometallic catalysis. More recently, a small range of complexes has been prepared in which alternative NHC isomers, namely imidazol-5-ylidenes (also termed abnormal NHCs or aNHCs, because the carbene center is no longer located between the two nitrogens), coordinate to a transition metal. Here we report the synthesis of a metal-free aNHC that is stable at room temperature, both in the solid state and in solution. Calculations show that the aNHC is more basic than its normal NHC isomer. Because the substituent at the carbon next to the carbene center is a nonbulky phenyl group, a variety of substitution patterns should be tolerated without precluding the isolation of the corresponding aNHC. PMID:19900893

  12. The 'Room within a Room' Concept for Monitored Warhead Dismantlement

    SciTech Connect

    Tanner, Jennifer E.; Benz, Jacob M.; White, Helen; McOmish, Sarah; Allen, Keir; Tolk, Keith; Weeks, George E.

    2014-12-01

    Over the past 10 years, US and UK experts have engaged in a technical collaboration with the aim of improving scientific and technological abilities in support of potential future nuclear arms control and non-proliferation agreements. In 2011 a monitored dismantlement exercise provided an opportunity to develop and test potential monitoring technologies and approaches. The exercise followed a simulated nuclear object through a dismantlement process and looked to explore, with a level of realism, issues surrounding device and material monitoring, chain of custody, authentication and certification of equipment, data management and managed access. This paper focuses on the development and deployment of the ‘room-within-a-room’ system, which was designed to maintain chain of custody during disassembly operations. A key challenge for any verification regime operating within a nuclear weapon complex is to provide the monitoring party with the opportunity to gather sufficient evidence, whilst protecting sensitive or proliferative information held by the host. The requirement to address both monitoring and host party concerns led to a dual function design which: • Created a controlled boundary around the disassembly process area which could provide evidence of unauthorised diversion activities. • Shielded sensitive disassembly operations from monitoring party observation. The deployed room-within-a-room was an integrated system which combined a number of chain of custody technologies (i.e. cameras, tamper indicating panels and enclosures, seals, unique identifiers and radiation portals) and supporting deployment procedures. This paper discusses the bounding aims and constraints identified by the monitoring and host parties with respect to the disassembly phase, the design of the room-within-a-room system, lessons learned during deployment, conclusions and potential areas of future work. Overall it was agreed that the room-within-a-room approach was effective but

  13. Sputtering-deposition of Ru nanoparticles onto Al2O3 modified with imidazolium ionic liquids: synthesis, characterisation and catalysis.

    PubMed

    Foppa, Lucas; Luza, Leandro; Gual, Aitor; Weibel, Daniel E; Eberhardt, Dario; Teixeira, Sérgio R; Dupont, Jairton

    2015-02-14

    Well-distributed Ru nanoparticles (Ru-NPs) were produced over Al(2)O(3) supports modified with covalently anchored imidazolium ionic liquids (ILs) containing different anions and cation lateral alkyl chain lengths by simple sputtering from a Ru foil. These Ru-NPs were active catalysts for the hydrogenation of benzene. Furthermore, depending on the nature of the IL used to modify the support (hydrophilic or hydrophobic), different catalytic behaviours were observed. Turnover numbers (TON) as high as 27 000 with a turnover frequency (TOF) of 2.73 s(-1) were achieved with Ru-NPs of 6.4 nm supported in Al(2)O(3) modified with an IL containing the N(SO(2)CF(3))2(-) anion, whereas higher initial cyclohexene selectivities (ca. 20% at 1% benzene conversion) were attained for Ru-NPs of 6.6 nm in the case where Cl(-) and BF(4)(-) anions were used. Such observations strongly suggest that thin layers of ILs surround the NP surface, modifying the reactivity of these catalytic systems. These findings open a new window of opportunity in the development of size-controlled Ru-NPs with tuneable reactivity.

  14. Fabrication of optical element from unidirectional grown imidazole-imidazolium picrate monohydrate (IIP) organic crystals for nonlinear optical applications

    NASA Astrophysics Data System (ADS)

    Vivek, P.; Murugakoothan, P.

    2014-12-01

    Nonlinear optical bulk single crystal of Imidazole-imidazolium picrate monohydrate (IIP) has been grown by Sankaranarayanan-Ramasamy (SR) method using acetonitrile as solvent. First time we report the bulk growth of IIP crystal by SR method. The transparent IIP single crystal of maximum diameter 21 mm and length 46 mm was obtained by employing SR method. The grown crystal was subjected to high resolution X-ray diffraction, UV-vis-NIR transmittance, refractive index, hardness, dielectric and laser damage threshold studies. The crystalline perfection of the grown crystal was analyzed using HRXRD. Cut off wavelength and optical transmission window of the crystal was assessed by UV-vis-NIR and the refractive index of the crystal was found. The mechanical property of the crystal was estimated by Vicker's hardness test. The dielectric property of the crystal was measured as a function of frequency. The laser damage threshold value was determined. The particle size dependent second harmonic generation efficiency for IIP was evaluated with standard reference material potassium dihydrogen phosphate (KDP) by Kurtz-Perry powder method using Nd:YAG laser, which established the existence of phase matching. The second harmonic generation (SHG) of IIP crystal was investigated by the SHG Maker fringes technique. The mechanism of growth is revealed by carrying out chemical etching using acetonitrile as etchant.

  15. 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].

  16. Effect of alkyl chain length and hydroxyl group functionalization on the surface properties of imidazolium ionic liquids.

    PubMed

    Pensado, Alfonso S; Costa Gomes, Margarida F; Canongia Lopes, José N; Malfreyt, Patrice; Pádua, Agílio A H

    2011-08-14

    Properties of the surface of ionic liquids, such as surface tension, ordering, and charge and density profiles, were studied using molecular simulation. Two types of modification in the molecular structure of imidazolium cations were studied: the length of the alkyl side chain and the presence of a polar hydroxyl group at the end of the side chain. Four ionic liquids were considered: 1-ethyl-3-methylimidazolium tetrafluoroborate, [C(2)C(1)im][BF(4)]; 1-(2-hydroxyethyl)-3-methylimidazolium tetrafluoroborate, [C(2)OHC(1)im][BF(4)]; 1-octyl-3-methylimidazolium tetrafluoroborate, [C(8)C(1)im][BF(4)] and 1-(8-hydroxyoctyl)-3-methylimidazolium tetrafluoroborate, [C(8)OHC(1)im][BF(4)]. The surface tension was calculated using both mechanical and thermodynamic definitions, with consistent treatment of the long-range corrections. The simulations reproduce the available experimental values of surface tension with a maximum deviation of ±10%. This energetic characterization of the interface is completed by microscopic structural analysis of orientational ordering at the interface and density profiles along the direction normal to the interface. The presence of the hydroxyl group modifies the local structure at the interface, leading to a less organized liquid phase. The results allow us to relate the surface tension to the structural ordering at the liquid-vacuum interface.

  17. Biomedical Exploitation of Chitin and Chitosan via Mechano-Chemical Disassembly, Electrospinning, Dissolution in Imidazolium Ionic Liquids, and Supercritical Drying

    PubMed Central

    Muzzarelli, Riccardo A. A.

    2011-01-01

    Recently developed technology permits to optimize simultaneously surface area, porosity, density, rigidity and surface morphology of chitin-derived materials of biomedical interest. Safe and ecofriendly disassembly of chitin has superseded the dangerous acid hydrolysis and provides higher yields and scaling-up possibilities: the chitosan nanofibrils are finding applications in reinforced bone scaffolds and composite dressings for dermal wounds. Electrospun chitosan nanofibers, in the form of biocompatible thin mats and non-wovens, are being actively studied: composites of gelatin + chitosan + polyurethane have been proposed for cardiac valves and for nerve conduits; fibers are also manufactured from electrospun particles that self-assemble during subsequent freeze-drying. Ionic liquids (salts of alkylated imidazolium) are suitable as non-aqueous solvents that permit desirable reactions to occur for drug delivery purposes. Gel drying with supercritical CO2 leads to structures most similar to the extracellular matrix, even when the chitosan is crosslinked, or in combination with metal oxides of interest in orthopedics. PMID:22131955

  18. Synthesis and performance of novel anion exchange membranes based on imidazolium ionic liquids for alkaline fuel cell applications

    NASA Astrophysics Data System (ADS)

    Fang, Jun; Lyu, Ming; Wang, Xin; Wu, Yongbin; Zhao, Jinbao

    2015-06-01

    Novel anion exchange membranes (AEMs) based on two types of imidazolium ionic liquids, 1-vinyl-3-methylimidazolium iodide [VMI]I and 1-vinyl-3-butylimidazolium bromide [VBI]Br, have been synthesized by copolymerization. The obtained membranes are characterized in terms of water uptake, ion exchange capacity (IEC), ionic conductivity as well as thermal and chemical stability. The conductivity reaches 0.0226 Scm-1 at 30 °C. All the membranes show excellent thermostability. The membranes are stable in 10 mol L-1 NaOH solution at 60 °C for 120 h without obvious changes in ion conductivity. Fuel cell performance using the resulting membrane has been investigated. The open circuit voltage (OCV) of the H2/O2 fuel cell is 1.07 V. A peek power density of 116 mW cm-2 is obtained at a current density of 230 mA cm-2 at 60 °C. The results demonstrate the brilliant prospect of the developed membranes for alkaline fuel cell applications.

  19. Tribological properties of self-assembled monolayers of catecholic imidazolium and the spin-coated films of ionic liquids.

    PubMed

    Liu, Jianxi; Li, Jinlong; Yu, Bo; Ma, Baodong; Zhu, Yangwen; Song, Xinwang; Cao, Xulong; Yang, Wu; Zhou, Feng

    2011-09-20

    A novel compound of an imidazolium type of ionic liquid (IL) containing a biomimetic catecholic functional group normally seen in mussel adhesive proteins was synthesized. The IL can be immobilized on a silicon surface and a variety of other engineering material surfaces via the catecholic anchor, allowing the tribological protection of these substrates for engineering applications. The surface wetting and adhesive properties and the tribological property of the synthesized self-assembled monolayers (SAMs) are successfully modulated by altering the counteranions. The chemical composition and wettability of the IL SAMs were characterized by means of X-ray photoelectron spectroscopy (XPS) and contact angle (CA) measurements. The adhesive and friction forces were measured with an atomic force microscope (AFM) on the nanometer scale. IL composite films were prepared by spin coating thin IL films on top of the SAMs. The macrotribological properties of these IL composite films were investigated with a pin-on-disk tribometer. The results indicate that the presence of IL SAMs on a surface can improve the wettability of spin-coated ionic liquids and thus the film quality and the tribological properties. These films registered a reduced friction coefficient and a significantly enhanced durability and load-carrying capacity. The tribological properties of the composite films are better than those of pure IL films because the presence of the monolayers improves the adhesion and compatibility of spin-coated IL films with substrates.

  20. Effects of imidazolium-based ionic surfactants on the size and dynamics of phosphatidylcholine bilayers with saturated and unsaturated chains.

    PubMed

    Lee, Hwankyu

    2015-07-01

    Imidazolium-based ionic surfactants of different sizes were simulated with 1,2-dimyristoyl-sn-glycero-3-phosphocholine (DMPC), 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine (POPC), and 1,2-dioleoyl-sn-glycero-3-phosphocholine (DOPC) bilayers. Regardless of the phospholipid type, larger surfactants at higher concentrations more significantly insert into the bilayer and increase the bilayer-surface size, in agreement with experiments and previous simulations. Insertion of surfactants only slightly decreases the bilayer thickness, as also observed in experiments. Although the surfactant insertion and its effect on the bilayer size and thickness are similar in different types of bilayers, the volume fractions of surfactants in the bilayer are higher for DMPC bilayers than for POPC and DOPC bilayers. In particular, ionic surfactants with four hydrocarbons yield their volume fractions of 4.6% and 8.7%, respectively, in POPC and DMPC bilayers, in quantitative agreement with experimental values of ∼5% and ∼10%. Also, the inserted surfactants increase the lateral diffusivity of the bilayer, which depends on the bilayer type. These findings indicate that although the surfactant insertion does not depend on the bilayer type, the effects of surfactants on the volume fraction and bilayer dynamics occur more significantly in the DMPC bilayer because of the smaller area per lipid and shorter saturated tails, which helps explain the experimental observations regarding different volume fractions of surfactants in POPC and DMPC bilayers.

  1. Analysis of the heterogeneous dynamics of imidazolium-based [Tf2N-] ionic liquids using molecular simulation

    NASA Astrophysics Data System (ADS)

    Androulaki, Eleni; Vergadou, Niki; Economou, Ioannis G.

    2014-10-01

    The complex dynamic behaviour of the imidazolium-based ionic liquids [Cnmim+][Tf2N-], n = 4, 8, 12 is examined at various temperatures and at atmospheric pressure using molecular dynamics simulation. An existing all-atom force field is further optimised in order to attain reasonable agreement with experimental data for transport properties, such as self-diffusivities and viscosities. Dynamical heterogeneity phenomena are quantified through the calculation of the non-Gaussian parameter and the deviation of the self-part of the van Hove correlation function from the expected normal distribution. From this analysis, ions that move faster or slower than expected are detected in the system. These subsets of 'fast' and 'slow' ions form individual clusters consisting of either mobile or immobile ions. Detailed analysis of the ions' diffusion reveals preferential motion along the direction of the alkyl tail for the cation and along the vector that connects the two sulphur atoms for the anion. For the longest alkyl tails, the heterogeneity in the dynamics becomes more pronounced and is preserved for several nanoseconds, especially at low temperatures.

  2. 1H, 13C NMR and DFT Study of Hydrogen Bonding in Imidazolium-based Ionic Liquids.

    PubMed

    Balevičius, Vytautas; Gdaniec, Zofia; Džiaugys, Lukas; Kuliešius, Feliksas; Maršalka, Arūnas

    2011-09-01

    The ionic liquid 1-decyl-3-methyl-imidazolium bromide [C10mim][Br], the neat material, and also dissolved (~0.01 mole fraction) in various dielectric media (acetonitrile, benzene, chloroform, dichloromethane, methanol, 2-butanol and H2O) was studied using 1H and 13C NMR spectroscopy. The most important interaction in this compound is considered to be the Br-...H-C2+ hydrogen bond, which is formed between the anions and cations. The obtained results show that dielectric medium influence mostly the behavior of the Br-...H-C2+ bridge proton. The changes observed in 1H and 13C NMR spectra of [C10mim][Br] with increasing solvents polarity and temperature can be explained applying the model of the lengthening of the H2...Br- bond with the accompanying thickening of the solvation shell of bromine anion and C2-H bond contraction. The short-range order effects related to the configuration of neighboring dipoles of solvent molecules are more important for the solvation ability of small anions than the bulk solvent field effect. However, the solvents, molecules of which tend to associate via hydrogen bonding, can significantly affect the dynamics of anions.

  3. Synthesis of novel chiral imidazolium stationary phases and their enantioseparation evaluation by high-performance liquid chromatography.

    PubMed

    Wang, Tao; Yang, Haiyan; Qiu, Ruchen; Huang, Shaohua

    2016-11-09

    Two novel chiral stationary phases (CSPs) were prepared by bonding chiral imidazoliums on the surface of silica gel. The chiral imidazoles were derivatized from chiral amines, 1-phenylethylamine and 1-(1-naphthyl)ethylamine. The obtained CSPs were characterized by Fourier Transform Infrared (FT-IR) spectroscopy and elemental analysis (EA), demonstrating the bonding densities of CSP 1 and CSP 2 were 0.43 mmol g(-1) and 0.40 mmol g(-1), respectively. These two CSPs could be used to availably separate 8 pharmaceuticals, 7 mandelic acid/its derivatives, 2 1-phenylethylamine derivatives, 1 1,1'-bi-2-naphthol, and 1 camphorsulfonic acid in high-performance liquid chromatography (HPLC). It is found that CSP 1 could effectively enantioseparate most chiral analytes, especially the acidic components, while CSP 2 could enantiorecognize all chiral analytes, although a number of components did not achieve baseline separation. Additionally, the effects of mobile phase composition, mobile phase pH and salt content, chiral selector structures, and analyte structures on the enantiorecognitions of the two CSPs were investigated. It is found that high acetonitrile content in mobile phases was conducive to enantiorecognition. Mobile phase pH and salt content could alter the retention behaviors of different enantiomers of the same chiral compound, resulting in better enantioresolution. Moreover, both chiral selector structures and substituted groups of analytes played a significant role in the separation of chiral solutes.

  4. Effects of imidazolium ionic liquids on growth, photosynthetic efficiency, and cellular components of the diatoms Skeletonema marinoi and Phaeodactylum tricornutum.

    PubMed

    Samorì, Chiara; Sciutto, Giorgia; Pezzolesi, Laura; Galletti, Paola; Guerrini, Franca; Mazzeo, Rocco; Pistocchi, Rossella; Prati, Silvia; Tagliavini, Emilio

    2011-03-21

    This article describes the toxic effects of imidazolium ionic liquids bearing alkyl (BMIM), monoethoxy (MOEMIM), and diethoxy (M(OE)(2)MIM) side chains toward two marine diatoms, Skeletonema marinoi and Phaeodactylum tricornutum. MOEMIM and M(OE)(2)MIM cations showed a lower inhibition of growth and photosynthetic efficiency with respect to their alkyl counterpart, with both algal species. However, a large difference in sensitivity was found between S. marinoi and P. tricornutum, the first being much more sensitive to the action of ionic liquids than the second one. The effects of salinity on BMIM Cl toxicity toward S. marinoi revealed that a decrease from salinity 35 to salinity 15 does not influence the biological effects toward the alga. Finally, Fourier transform infrared (FT-IR) microscopy of algal cells after ionic liquids exposure allowed us to detect an alteration of the organic cellular components related to silica uptake and organization. On the basis of these results, the different behavior of the two diatom species can be tentatively ascribed to different silica uptake and organization in outer cell walls.

  5. Water-in-ionic liquid microemulsion formation in solvent mixture of aprotic and protic imidazolium-based ionic liquids.

    PubMed

    Kusano, Takumi; Fujii, Kenta; Hashimoto, Kei; Shibayama, Mitsuhiro

    2014-10-14

    We report that water-in-ionic liquid microemulsions (MEs) are stably formed in an organic solvent-free system, i.e., a mixture of aprotic (aIL) and protic (pIL) imidazolium-based ionic liquids (ILs) containing the anionic surfactant dioctyl sulfosuccinate sodium salt (AOT). Structural investigations using dynamic light, small-angle X-ray, and small-angle neutron scatterings were performed for MEs formed in mixtures of aprotic 1-octyl-3-methylimidazolium ([C8mIm(+)]) and protic 1-alkylimidazolium ([CnImH(+)], n = 4 or 8) IL with a common anion, bis(trifluoromethanesulfonyl)amide ([TFSA(-)]). It was found that the ME structure strongly depends on the mixing composition of the aIL/pIL in the medium. The ME size appreciably increases with increasing pIL content in both [C8mIm(+)][TFSA(-)]/[C8ImH(+)][TFSA(-)] and [C8mIm(+)][TFSA(-)]/[C4ImH(+)][TFSA(-)] mixtures. The size is larger for the n = 8 system than that for the n = 4 system. These results indicate that the shell part of MEs is composed of both AOT and pIL cation, and the ME size can be tuned by pIL content in the aIL/pIL mixtures.

  6. Effect of Imidazolium-Based Silver Nanoparticles on Root Dentin Roughness in Comparison with Three Common Root Canal Irrigants

    PubMed Central

    Farshad, Melika; Abbaszadegan, Abbas; Ghahramani, Yasamin; Jamshidzadeh, Akram

    2017-01-01

    Introduction: The aim of this study was to evaluate the effect of a nanosilver-based irrigant on dentin roughness in comparison with three commonly used root canal irrigation solutions. Methods and Materials: Three common irrigants including 5.25% sodium hypochlorite (NaOCl), 17% ethylenediaminetetraacetic acid (EDTA) and 2% chlorhexidine (CHX) and also an imidazolium-based silver nanoparticle solution (ImSNP) (5.7×10 -8 mol/L), were used. Distilled water was used as control. Roots of 25 human anterior teeth were sectioned longitudinally to obtain 50 dentin samples. Roughness values were evaluated by atomic force microscopy analysis on 5 groups (n=10) after each group was treated in one of the tested irrigant solutions for 10 min. Values were statistically analyzed by One-way analysis of variance, followed by a post hoc Tukey’s test for pair-wise comparison. Results: Dentin roughness significantly increased from 95.82 nm (control) to 136.02 nm, 187.07 nm, 142.29 nm and 150.92 nm with NaOCl, CHX, ImSNP and EDTA, respectively. CHX demonstrated a significantly higher roughness value compared to the other tested irrigants while no significant differences were seen in NaOCl, ImSNP and EDTA groups (P>0.242). Conclusion: ImSNP affected the physicochemical properties of dentin and raised its surface roughness; thus, this irrigant could impact bacterial and restorative material adhesion to root canal dentin walls. PMID:28179931

  7. Anion effects on anti-microbial activity of poly[1-vinyl-3-(2-sulfoethyl imidazolium betaine)].

    PubMed

    Garg, Godawari; Chauhan, Ghanshyam S; Gupta, Reena; Ahn, J-H

    2010-04-01

    Recent investigations in the anti-microbial properties of the functional polymers are predominantly focused on the structure of the cationic moieties. In the present study, we investigated that the nature of the anion present in polysulfobetaines affects activity against certain microorganisms and their anti-microbial properties have been rationalized in terms of the structure-activity relationship. Vinyl imidazolium-based polysulfobetaines were prepared by the quaternization of poly(N-vinyl imidazole) with sodium salt of 2-bromo ethanesulfonic acid. The bromide counter anion of the resulting polymer was exchanged with different anions to generate a series of polymers. These were characterized by FTIR, DSC, XRD, SEM, elemental analysis (C, H, N and S) and viscosity measurements. The anti-microbial activity studies were carried against three fungi (Aspergillus niger, Byssochlamys fulva and Mucor circenelliods) and two bacteria (Bacillus coagulans BTS-3 and Pseudomonas aeruginosa BTS-2). The nature of the anion affects the structure of polysulfobetaine by realignment of polymer chains. The anion-dependent anti-microbial properties of polysulfobetaines result from the interaction of the microbes at the polymer interface.

  8. 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.

  9. Effects of alkyl-imidazolium ionic liquid [Omim]Cl on the functional diversity of soil microbial communities.

    PubMed

    Guo, Pengpeng; Zhu, Lusheng; Wang, Jinhua; Wang, Jun; Liu, Tong

    2015-06-01

    As low-temperature molten salts, ionic liquids (ILs) were considered to be "green" solvents and have begun to see large-scale applications in the chemical reactions, in separation processes, in electrochemistry studies, etc. In recent years, the toxicity of ILs has started to draw attention. To evaluate the effects of the ionic liquid [Omim]Cl on indigenous microbial community in soil, Biolog-ECO plate method were used with the addition of four different concentrations of [Omim]Cl after four different incubation periods (7, 14, 21, 28 days). The present results showed that the average well color development (AWCD) was strongly activated when the soil was contaminated with [Omim]Cl in the early stages of the incubation. However, the activation effect disappeared with extended incubation time. Therefore, the toxic effects of the alkyl-imidazolium ionic liquid ([Omim]Cl) on the functional diversity of soil microbial communities may be reversible. In addition, the kinetic characteristics of microorganisms that used different categories of carbon sources indicated that phenolic compounds were the main C source in the sample soil.

  10. New insight into the environmental impact of two imidazolium ionic liquids. Effects on seed germination and soil microbial activity.

    PubMed

    Salgado, J; Parajó, J J; Teijeira, T; Cruz, O; Proupín, J; Villanueva, M; Rodríguez-Añón, J A; Verdes, P V; Reyes, O

    2017-10-01

    The next generation of ionic liquids must be synthetized taking into account structures that guarantee the suitable properties for a defined application as well as ecological data. Thus, searching of the right methodologies to know, quickly and efficiently, the ecological effects of these compounds is a preliminary task. The effects of two imidazolium based ionic liquids with different anions, 1-butyl-3-methylimidazolium tetrafluoroborate, [C4C1Im][BF4], and 1-propyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide, [C3C1Im][NTf2], on seedling emergence of six tree species and on the microbial behaviour of two soils were determined in this work. Results showed that the highest doses of both ionic liquids caused the total inhibition of germination for almost all the species studied and that the seeds are more sensitive to the presence of these compounds than soil microbial activity. Nevertheless, signals of stress and death are observed from the results of heat released by microorganisms after the addition of the highest doses of both ionic liquids. The novelty of this work resides in the enlargement of knowledge of toxicity of ILs on complex organisms such as arboreal species and microbial activity of soils studied for the first time through a microcalorimetric technique. Copyright © 2017 Elsevier Ltd. All rights reserved.

  11. Effect of Imidazolium-Based Silver Nanoparticles on Root Dentin Roughness in Comparison with Three Common Root Canal Irrigants.

    PubMed

    Farshad, Melika; Abbaszadegan, Abbas; Ghahramani, Yasamin; Jamshidzadeh, Akram

    2017-01-01

    The aim of this study was to evaluate the effect of a nanosilver-based irrigant on dentin roughness in comparison with three commonly used root canal irrigation solutions. Three common irrigants including 5.25% sodium hypochlorite (NaOCl), 17% ethylenediaminetetraacetic acid (EDTA) and 2% chlorhexidine (CHX) and also an imidazolium-based silver nanoparticle solution (ImSNP) (5.7×10 (-8) mol/L), were used. Distilled water was used as control. Roots of 25 human anterior teeth were sectioned longitudinally to obtain 50 dentin samples. Roughness values were evaluated by atomic force microscopy analysis on 5 groups (n=10) after each group was treated in one of the tested irrigant solutions for 10 min. Values were statistically analyzed by One-way analysis of variance, followed by a post hoc Tukey's test for pair-wise comparison. Dentin roughness significantly increased from 95.82 nm (control) to 136.02 nm, 187.07 nm, 142.29 nm and 150.92 nm with NaOCl, CHX, ImSNP and EDTA, respectively. CHX demonstrated a significantly higher roughness value compared to the other tested irrigants while no significant differences were seen in NaOCl, ImSNP and EDTA groups (P>0.242). ImSNP affected the physicochemical properties of dentin and raised its surface roughness; thus, this irrigant could impact bacterial and restorative material adhesion to root canal dentin walls.

  12. Synthesis, growth, optical and anisotropic mechanical behaviour of organic nonlinear optical imidazolium 2-chloro-4-nitrobenzoate single crystals

    NASA Astrophysics Data System (ADS)

    Krishnakumar, Varadharajan; Jayaprakash, Jeyaram; Boobas, Singaram; Komathi, Muniraj

    2016-10-01

    The title compound, imidazolium 2-chloro-4-nitrobenzoate (I2C4NB), has been synthesized and optical quality single crystals were grown with a dimension of 4 × 2 × 1 mm3 using an ethanol and acetone (1:1) mixed solvent by slow evaporation solution growth technique. The powder XRD analysis confirmed the crystal structure and found that it is crystallized in the non-centrosymmetric space group P21 with the monoclinic system. The symmetries of molecular vibrations were confirmed by FT-IR spectrum. The CHN(S) analysis confirmed the stoichiometric composition of the grown crystal. It also exhibits a good transparency in the entire visible region (300-800nm) and it was thermally stable up to 131.1 °C. The microhardness measurement shows the anisotropic nature of I2C4NB and also that it belongs to a soft material category. Photoconductivity studies reveal a linear increase of the photocurrent with respect to the applied electric field. HOMO LUMO studies were carried out for the crystal. The second harmonic generation test by the Kurtz powder method shows that the crystal exhibits phase matching and a conversion efficiency which is 2 times that of KDP.

  13. An abnormal N-heterocyclic carbene-carbon dioxide adduct from imidazolium acetate ionic liquids: the importance of basicity.

    PubMed

    Kelemen, Zsolt; Péter-Szabó, Barbara; Székely, Edit; Hollóczki, Oldamur; Firaha, Dzmitry S; Kirchner, Barbara; Nagy, József; Nyulászi, László

    2014-09-26

    In the reaction of 1-ethyl-3-methylimidazolium acetate [C2C1Im][OAc] ionic liquid with carbon dioxide at 125 °C and 10 MPa, not only the known N-heterocyclic carbene (NHC)-CO2 adduct I, but also isomeric aNHC-CO2 adducts II and III were obtained. The abnormal NHC-CO2 adducts are stabilized by the presence of the polarizing basic acetate anion, according to static DFT calculations and ab initio molecular dynamics studies. A further possible reaction pathway is facilitated by the high basicity of the system, deprotonating the initially formed NHC-CO2 adduct I, which can then be converted in the presence of the excess of CO2 to the more stable 2-deprotonated anionic abnormal NHC-CO2 adduct via the anionic imidazolium-2,4-dicarboxylate according to DFT calculations on model compounds. This suggests a generalizable pathway to abnormal NHC complex formation.

  14. Thermodynamic Insights into the Binding of Mono- and Dicationic Imidazolium Surfactant Ionic Liquids with Methylcellulose in the Diluted Regime.

    PubMed

    Ziembowicz, Francieli Isa; Bender, Caroline Raquel; Frizzo, Clarissa Piccinin; Martins, Marcos Antonio Pinto; de Souza, Thiane Deprá; Kloster, Carmen Luisa; Santos Garcia, Irene Teresinha; Villetti, Marcos Antonio

    2017-08-25

    Alkylimidazolium salts are an important class of ionic liquids (ILs) due to their self-assembly capacity when in solution and due to their potential applications in chemistry and materials science. Therefore, detailed knowledge of the physicochemical properties of this class of ILs and their mixtures with natural polymers is highly desired. This work describes the interactions between a homologous series of mono- (CnMIMBr) and dicationic imidazolium (Cn(MIM)2Br2) ILs with cellulose ethers in aqueous medium. The effects of the alkyl chain length (n = 10, 12, 14, and 16), type, and concentration range of ILs (below and above their cmc) on the binding to methylcellulose (MC) were evaluated. The thermodynamic parameters showed that the interactions are favored by the increase of the IL hydrocarbon chain length, and that the binding of monocationic ILs to MC is driven by entropy. The monocationic ILs bind more effectively on the methoxyl group of MC when compared to dicationic ILs, and this outcome may be rationalized by considering the structural difference between the conventional (CnMIMBr) and the bolaform (Cn(MIM)2Br2) surfactant ILs. The C16MIMBr interacts more strongly with hydroxypropylcellulose when compared to methylcellulose, indicating that the strength of the interaction also depends on the hydrophobicity of the cellulose ethers. Our findings highlight that several parameters should be taken into account when designing new complex formulations.

  15. Synthesis, growth, structure, mechanical and optical properties of a new semi-organic 2-methyl imidazolium dihydrogen phosphate single crystal

    SciTech Connect

    Nagapandiselvi, P.; Baby, C.; Gopalakrishnan, R.

    2016-09-15

    Highlights: • 2MIDP crystals were grown by slow evaporation solution growth technique. • Single crystal XRD revealed self-assembled supramolecular framework. • Z scan technique is employed for third order nonlinear optical susceptibility. • Structure-property correlation is established. - Abstract: A new semi-organic compound, 2-methyl imidazolium dihydrogen phosphate (2MIDP), was prepared and good quality single crystals of 2MIDP were grown by slow evaporation solution growth technique. Crystal structure elucidated using Single crystal XRD showed that 2MIDP crystallizes in monoclinic system with P2{sub 1}/c space group. FT-IR, UV-Vis-NIR, Fluorescence and FT-NMR spectra confirm the molecular structure of 2MIDP. The UV-Vis-NIR spectra established the suitability of the compound for NLO applications. TG-DSC showed that 2MIDP is thermally stable up to 200 °C. Mechanical characteristics like hardness number (H{sub v}), stiffness constant (C{sub 11}), yield strength (σ{sub v}), fracture toughness (K{sub c}) and brittleness index (B{sub i}) were assessed using Vicker’s microhardness tester. Third order nonlinear optical properties determined from Z-scan measurement using femto and picosecond lasers showed two photon reverse saturable absorption. The enhancement of nonlinear optical properties in femto second laser, revealed the suitability of 2MIDP for optical limiting applications.

  16. Imidazolium Ionic Liquid Functionalized Carbon Nanotubes for Improved Interfacial Charge Transfer and Simultaneous Determination of Dihydroxybenzene Isomers.

    PubMed

    Wei, Huan; Wu, Xiao-Shuai; Wen, Guo-Yun; Qiao, Yan

    2016-05-14

    In this paper; an imidazolium ionic liquid (IL) is used to functionalize multi-walled carbon nanotubes (MWNTs) by covalent bonding on the MWNT surface. The functionalization not only provides a hydrophilic surface for ion accessibility but also prevents the aggregation of MWNTs. The IL-functionalized MWNTs were then applied for the electrochemical determination of the dihydroxybenzene isomers hydroquinone (HQ); catechol (CC); and resorcinol (RC), exhibiting excellent recognition ability towards the three compounds. The linear calibration ranges for HQ; CC and RC are 0.9-150 μM; 0.9-150 μM and 1.9-145 μM and the detection limits are found to be 0.15 μM for HQ; 0.10 μM for CC and 0.38 μM for RC based on S/N of 3. The proposed electrochemical sensor was also found to be useful for the determination of the dihydroxybenzene isomers in Yellow River water with reliable recovery.

  17. Effectiveness and potential of straw- and wood-based biochars for adsorption of imidazolium-type ionic liquids.

    PubMed

    Shi, Kaishun; Qiu, Yuping; Ben Li; Stenstrom, Michael K

    2016-08-01

    The growing industrial application of imidazolium-type ionic liquids (ITILs) is likely to result in their release to the environment. Water-soluble ITILs are difficult to remove from wastewaters using traditional adsorbents. In this work, we developed different biochars derived from straw and wood (named as SBB and WBB, respectively) to improve the adsorption effectiveness for removal of ITILs from wastewaters. SBB had high O/C element ratio (0.143), while WBB had high ratio of Vmicro/Vtotal (61.5%) compared with commercial activated carbon (AC). Both of them showed greater adsorption of ITILs than AC with different adsorption mechanisms. FTIR spectra revealed that electrostatic interactions were the dominant driving force in SBB adsorption, while high micropore volume promoted adsorption in WBB. The adsorption of [C2mim][BF4] on SBB and WBB was strongly enhanced by trivalent PO4(3-) anions, suggesting that PO4(3-) anions could be used as promoter to increase the removal efficiency of ITILs from wastewater. Using HCl solution (pH=0.5) as regenerant, SBB and WBB were regenerated with nearly 100% recovery of adsorption capacity over ten consecutive adsorption-desorption cycles. Straw-based biochar and wood-based biochar are efficient sorbents for removal of water-soluble ionic liquids from aqueous solutions.

  18. 26. A typical outer rod room, or rack room, showing ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    26. A typical outer rod room, or rack room, showing the racks for the nine horizontal control rods (HCRs) that would be inserted or withdrawn from the pile to control the rate of reaction. In this case, it is the 105-F Reactor in February 1945. The view is looking away from the pile, which is out of the picture on the left. Several of the cooling water hose reels for the rods can be seen at the end of the racks near the wall. D-8323 - B Reactor, Richland, Benton County, WA

  19. 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.

  20. 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.

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

    SciTech Connect

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

    2011-01-01

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

  2. Ideal gas solubilities and solubility selectivities in a binary mixture of room-temperature ionic liquids

    SciTech Connect

    Finotello Alexia; Bara Jason E.; Narayan Suguna; Campder Dean; Noble Richard D.

    2008-07-01

    This study focuses on the solubility behaviors of CO{sub 2}, CH{sub 4}, and N{sub 2} gases in binary mixtures of imidazolium-based room-temperature ionic liquids (RTILs) using l-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)-imide ((C{sub 2}mim)(Tf{sub 2}N)) and l-ethyl-3-methylimidazolium tetrafluoroborate ((C{sub 2}mim)(BF{sub 4})) at 40{sup o}C and low pressures (about 1 atm). The mixtures tested were 0, 25, 50, 75, 90, 95, and 100 mol % (C{sub 2}mim)(BF{sub 4}) in (C{sub 2}-mim)(Tf2{sub N}). Results show that regular solution theory (RST) can be used to describe the gas solubility and selectivity behaviors in RTIL mixtures using an average mixture solubility parameter or an average measured mixture molar volume. Interestingly, the solubility selectivity, defined as the ratio of gas mole fractions in the RTIL mixture, of CO{sub 2} with N{sub 2} or CH{sub 4} in pure (C{sub 2}mim)(BF4) can be enhanced by adding 5 mol% (C{sub 2}-mim)(Tf{sub 2}N).

  3. Effects of Room-Temperature Ionic Liquids on Zebra Mussels (Dreissena polymorpha)

    NASA Astrophysics Data System (ADS)

    Costello, D. M.; Bernot, R. J.; Lamberti, G. A.

    2005-05-01

    Zebra mussels (Dreissena polymorpha) are exotic bivalves that are widely distributed in eastern North America. We propose that this nuisance organism could serve as a model species for studies of aquatic toxicology. We tested zebra mussels response to room-temperature ionic liquids (ILs), which are being synthesized as environmentally friendly alternatives to volatile organic solvents. Volatile organic solvents contribute to atmospheric pollution and ozone depletion, whereas ILs are non-volatile and less harmful to the atmosphere. Although ILs would contribute significantly less to air pollution, little is known about their potential effects on aquatic ecosystems. In 72-hour toxicity tests, we determined the acute effects of three imidazolium-based ILs (1-butyl-3-methylimidazolium bromide (bmimBr), 1-hexyl-3-methylimidazolium bromide (hmimBr), and 1-octyl-3-methylimidazolium bromide (omimBr)) on the survival of zebra mussels. As alkyl chain length decreased, median lethal concentration (LC50) decreased from 1291 mg L-1 for bmimBr, to 105 mg L-1 for hmimBr, and 21.2 mg L-1 for omimBr. For bivalve mussels, the toxicities of these ILs are comparable to the toxicities of commonly used industrial solvents (e.g., toluene, benzene). This study presents a foundation for using zebra mussels in toxicity studies as well as possible models for less common Unionid mussels.

  4. Ideal gas solubilities and solubility selectivities in a binary mixture of room-temperature ionic liquids.

    PubMed

    Finotello, Alexia; Bara, Jason E; Narayan, Suguna; Camper, Dean; Noble, Richard D

    2008-02-28

    This study focuses on the solubility behaviors of CO2, CH4, and N2 gases in binary mixtures of imidazolium-based room-temperature ionic liquids (RTILs) using 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ([C2mim][Tf2N]) and 1-ethyl-3-methylimidazolium tetrafluoroborate ([C2mim][BF4]) at 40 degrees C and low pressures (approximately 1 atm). The mixtures tested were 0, 25, 50, 75, 90, 95, and 100 mol % [C2mim][BF4] in [C2mim][Tf2N]. Results show that regular solution theory (RST) can be used to describe the gas solubility and selectivity behaviors in RTIL mixtures using an average mixture solubility parameter or an average measured mixture molar volume. Interestingly, the solubility selectivity, defined as the ratio of gas mole fractions in the RTIL mixture, of CO2 with N2 or CH4 in pure [C2mim][BF4] can be enhanced by adding 5 mol % [C2mim][Tf2N].

  5. 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.

  6. Translation-rotation decoupling and nonexponentiality in room temperature ionic liquids

    SciTech Connect

    Griffin, Phillip; Agapov, Alexander L; Sokolov, Alexei P

    2012-01-01

    Using a combination of light scattering techniques and broadband dielectric spectroscopy, we have measured the temperature dependence of structural relaxation time and self diffusion in three imidazolium-based room temperature ionic liquids: [bmim][NTf2], [bmim][PF6], and [bmim][TFA]. A detailed analysis of the results demonstrates that self diffusion decouples from structural relaxation in these systems as the temperature is decreased toward Tg. The degree to which the dynamics are decoupled, however, is shown to be surprisingly weak when compared to other supercooled liquids of similar fragility. In addition to the weak decoupling, we demonstrate that the temperature dependence of the structural relaxation time in all three liquids can be well described by a single Vogel-Fulcher-Tamann function over 13 decades in time from 10 11 s up to 102 s. Furthermore, the stretching of the structural relaxation is shown to be temperature independent over the same range of time scales, i.e., time temperature superposition is valid for these ionic liquids from far above the melting point down to the glass transition temperature.We suggest that these phenomena are interconnected and all result from the same underlying mechanism strong and directional intermolecular interactions.

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

    PubMed

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

    2012-10-11

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

  8. Ozone decontamination of bioclean rooms.

    PubMed Central

    Masaoka, T; Kubota, Y; Namiuchi, S; Takubo, T; Ueda, T; Shibata, H; Nakamura, H; Yoshitake, J; Yamayoshi, T; Doi, H; Kamiki, T

    1982-01-01

    To establish a convenient method for decontaminating bioclean rooms, the effect of ozone at 80 mg/m3 for 72 h was compared with formaldehyde vaporization at an initial concentration of 150 mg/m3 with a gradual decrease to 20 mg/m3 during 72 h. Ozone was found to be inferior to formaldehyde in activity. When the bioclean room was decontaminated twice with ozone, the mean colony count per 10 cm2 was decreased to about the same level as when formaldehyde was used. Ozone had a strong caustic effect upon rubber materials. Despite these disadvantages, ozone decontamination was demonstrated to be superior to formaldehyde vaporization because of convenience, insignificant inhalation of the disinfectant by the hospital staff, and very rapid expulsion of the gas after ventilation. Because the disadvantages of ozone can be easily controlled, this study suggests that ozone decontamination is a promising method for maintaining bioclean rooms. PMID:6803668

  9. Complex soundproofing of industrial rooms

    NASA Technical Reports Server (NTRS)

    Pocsa, V.; Veres, A.; Biborosch, L.

    1974-01-01

    Some structures treated for sound absorption are described that are used to soundproof industrial rooms with a very high noise level. Soundproofing treatments for the walls and coilings or only for the ceilings are considered. In the case of relatively small rooms having a noise source with a high level, complex treatments involve, in addition to soundproofing of the walls and ceiling, suspended panels specially oriented with respect to the noise source. The efficiency of the adopted solutions is compared with calculated damping values.

  10. Complex soundproofing of industrial rooms

    NASA Technical Reports Server (NTRS)

    Pocsa, V.; Veres, A.; Biborosch, L.

    1974-01-01

    Some structures treated for sound absorption are described that are used to soundproof industrial rooms with a very high noise level. Soundproofing treatments for the walls and coilings or only for the ceilings are considered. In the case of relatively small rooms having a noise source with a high level, complex treatments involve, in addition to soundproofing of the walls and ceiling, suspended panels specially oriented with respect to the noise source. The efficiency of the adopted solutions is compared with calculated damping values.

  11. Room temperature terahertz polariton emitter

    SciTech Connect

    Geiser, Markus; Scalari, Giacomo; Castellano, Fabrizio; Beck, Mattias; Faist, Jerome

    2012-10-01

    Terahertz (THz) range electroluminescence from intersubband polariton states is observed in the ultra strong coupling regime, where the interaction energy between the collective excitation of a dense electron gas and a photonic mode is a significant portion of the uncoupled excitation energy. The polariton's increased emission efficiency along with a parabolic electron confinement potential allows operation up to room temperature in a nonresonant pumping scheme. This observation of room temperature electroluminescence of an intersubband device in the THz range is a promising proof of concept for more powerful THz sources.

  12. Hygiene and room climate in the operating room.

    PubMed

    Scherrer

    2003-11-01

    The ventilation system is not the most important source to cause surgical site infections via the air. More important is the skin of both staff and patients. The literature did not reveal any reduction of the risk of surgical site infections resulting from the employment of ultra-clean air-systems during surgical procedures, the one exception being high risk operations such as orthopaedic implant surgery. Both ultra-clean air and antimicrobial prophylaxis can reduce the incidence of surgical site infections. If HEPA filters are used, they are only necessary directly in the operating rooms. Other rooms such as the washroom, the anaesthesia preparation room or corridors which are connected to the OR do not have to be treated with HEPA filters. If a laminar air-flow system is installed, there are some factors which have to be considered. The number of operating lamps and the heads of the operating team affect the function of the air ceiling as they form thermic and air-flow resistance and create turbulences. Also, forced air-warming systems, which are used to maintain normal body temperatures for patients during surgery, disturb the ultra-clean field through the air emitted from the blankets used. Moreover, any medical equipment which is cooled by integrated cooling blowers can influence an ultra-clean air system. Existing ventilation systems are not able to create good room conditions for all persons inside the OR. Therefore new ways have to be found to create a room climate taking into account the level of activity.

  13. 39 CFR 3004.12 - Reading room.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 39 Postal Service 1 2010-07-01 2010-07-01 false Reading room. 3004.12 Section 3004.12 Postal... Reading room. (a) The Commission maintains a public reading room at its offices (901 New York Avenue, NW., Suite 200, Washington, DC 20268-0001) and an electronic reading room at http://www.prc.gov. The...

  14. 39 CFR 3004.12 - Reading room.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 39 Postal Service 1 2012-07-01 2012-07-01 false Reading room. 3004.12 Section 3004.12 Postal... Reading room. (a) The Commission maintains a public reading room at its offices (901 New York Avenue, NW., Suite 200, Washington, DC 20268-0001) and an electronic reading room at http://www.prc.gov. The...

  15. 39 CFR 3004.12 - Reading room.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 39 Postal Service 1 2011-07-01 2011-07-01 false Reading room. 3004.12 Section 3004.12 Postal... Reading room. (a) The Commission maintains a public reading room at its offices (901 New York Avenue, NW., Suite 200, Washington, DC 20268-0001) and an electronic reading room at http://www.prc.gov. The...

  16. 39 CFR 3004.12 - Reading room.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 39 Postal Service 1 2014-07-01 2014-07-01 false Reading room. 3004.12 Section 3004.12 Postal... Reading room. (a) The Commission maintains a public reading room at its offices (901 New York Avenue, NW., Suite 200, Washington, DC 20268-0001) and an electronic reading room at http://www.prc.gov. The...

  17. 32 CFR 296.6 - Reading room.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 32 National Defense 2 2012-07-01 2012-07-01 false Reading room. 296.6 Section 296.6 National... Reading room. (a) The NRO shall provide a reading room equipped with hard copy and electronic records as required in the “Electronic Freedom of Information Act Amendments of 1996”. The NRO Reading Room is...

  18. 32 CFR 296.6 - Reading room.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 32 National Defense 2 2014-07-01 2014-07-01 false Reading room. 296.6 Section 296.6 National... Reading room. (a) The NRO shall provide a reading room equipped with hard copy and electronic records as required in the “Electronic Freedom of Information Act Amendments of 1996”. The NRO Reading Room is...

  19. 32 CFR 296.6 - Reading room.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 32 National Defense 2 2013-07-01 2013-07-01 false Reading room. 296.6 Section 296.6 National... Reading room. (a) The NRO shall provide a reading room equipped with hard copy and electronic records as required in the “Electronic Freedom of Information Act Amendments of 1996”. The NRO Reading Room is...

  20. 39 CFR 3004.12 - Reading room.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 39 Postal Service 1 2013-07-01 2013-07-01 false Reading room. 3004.12 Section 3004.12 Postal... Reading room. (a) The Commission maintains a public reading room at its offices (901 New York Avenue, NW., Suite 200, Washington, DC 20268-0001) and an electronic reading room at http://www.prc.gov. The...

  1. A simple guiding principle for the temperature dependence of the solubility of light gases in imidazolium-based ionic liquids derived from molecular simulations.

    PubMed

    Kerlé, Daniela; Namayandeh Jorabchi, Majid; Ludwig, Ralf; Wohlrab, Sebastian; Paschek, Dietmar

    2017-01-18

    We have determined the temperature dependence of the solvation behavior of a large collection of important light gases in imidazolium-based ionic liquids with the help of extensive molecular dynamics simulations. The motivation of our study is to unravel common features of the temperature dependent solvation under well controlled conditions, and to provide a guidance for cases, where experimental data from different sources disagree significantly. The solubility of molecular hydrogen, oxygen, nitrogen, methane, krypton, argon, neon and carbon dioxide in the imidazolium based ionic liquids of type 1-n-alkyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ([Cnmim][NTf2]) with varying alkyl side chain lengths n = 2, 4, 6, 8 is computed for a temperature range between 300 K and 500 K at 1 bar. By applying Widom's particle insertion technique and Bennet's overlapping distribution method, we are able to determine the temperature dependent solvation free energies of those selected light gases in simulated imidazolium based ionic liquids with high statistical accuracy. Our simulations demonstrate that the magnitude of the solvation free energy of a gas molecule at a chosen reference temperature and that of its temperature-derivatives are intimately related to one another. We conclude that this "universal" behavior is rooted in a solvation entropy-enthalpy compensation effect, which seems to be a defining feature of the solvation of small molecules in ionic liquids. The observations lead to simple analytical relations, determining the temperature dependence of the solubility data based on the absolute solubility at a certain reference temperature. By comparing our results with available experimental data from many sources, we can show that our approach is particularly helpful for providing reliable estimates for the solvation behavior of very light gases, such as hydrogen, where conflicting experimental data exist.

  2. Radiation induced physicochemical changes in FAP (fluoro alkyl phosphate) based imidazolium ionic liquids and their mechanistic pathways: influence of hydroxyl group functionalization of the cation.

    PubMed

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

    2014-01-14

    Future applications of ionic liquids (ILs) in a variety of areas, especially those having high radiation fields such as the nuclear fuel cycle and in space technology, are under serious consideration nowadays. For such applications to be possible, however, radiation stability of the ILs is an important issue that needs to be addressed. We envisaged that the ultra-hydrophobic, bulky and hydrolytically stable FAP (tris(perfluoroalkyl)trifluorophosphate) anion might shield the radiolytically vulnerable imidazolium cations from degradation and our result shows that these anions indeed enhance their radiolytic stability. However, introduction of a hydroxyl group into the alkyl side chain of the imidazolium moiety resulted in significant changes in the physical properties of the IL with respect to onset temperatures, conductivity and the electrochemical window. Furthermore, a nonlinear trend in absorbance with an increase in radiation dose accompanied by NMR (nuclear magnetic resonance) and mass spectrometry studies clearly demonstrated that the presence of the hydroxyl group promotes various degradation channels. Interestingly, a perturbation of the hydrogen bond between the hydroxyl group (present in the side chain of the cation) and the fluorine atom of the anion (OHF) was evident in the case of irradiated hydroxyl functionalized FAP ILs. Besides, the hydrogen gas yields of the ILs were determined and found to be comparable to those of a radiolytically stable aromatic compound, benzene. Finally, through transient spectroscopic studies we could delineate the mechanism of the radiation induced changes in the physicochemical properties of the non-hydroxyl and hydroxyl containing FAP ILs. We have clearly demonstrated that a simple functionalization of the molecular structure of the FAP based imidazolium ILs might cause marked differences in the reactivity, reaction center and the nature of the radiolytic products, which eventually lead to significant changes in their

  3. Self-diffusion and interactions in mixtures of imidazolium bis(mandelato)borate ionic liquids with polyethylene glycol: (1) H NMR study.

    PubMed

    Filippov, Andrei; Azancheev, Nail; Taher, Mamoun; Shah, Faiz Ullah; Rabét, Pauline; Glavatskih, Sergei; Antzutkin, Oleg N

    2015-07-01

    We used (1) H nuclear magnetic resonance pulsed-field gradient to study the self-diffusion of polyethylene glycol (PEG) and ions in a mixture of PEG and imidazolium bis(mandelato)borate ionic liquids (ILs) at IL concentrations from 0 to 10 wt% and temperatures from 295 to 370 K. PEG behaves as a solvent for these ILs, allowing observation of separate lines in (1) H NMR spectra assigned to the cation and anion as well as to PEG. The diffusion coefficients of PEG, as well as the imidazolium cation and bis(mandelato)borate (BMB) anion, differ under all experimental conditions tested. This demonstrates that the IL in the mixture is present in at least a partially dissociated state, while the lifetimes of the associated states of the ions and ions with PEG are less than ~30 ms. Generally, increasing the concentration of the IL leads to a decrease in the diffusion coefficients of PEG and both ions. The diffusion coefficient of the anion is less than that of the cation; the molecular mass dependence of diffusion of ions can be described by the Stokes-Einstein model. NMR chemical shift alteration analysis showed that the presence of PEG changes mainly the chemical shifts of protons belonging to imidazole ring of the cation, while chemical shifts of protons of anions and PEG remain unchanged. This demonstrated that the imidazolium cation interacts mainly with PEG, which most probably occurs through the oxygen of PEG and the imidazole ring. The BMB anion does not strongly interact with PEG, but it may be indirectly affected by PEG through interaction with the cation, which directly interacts with PEG.

  4. 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.

  5. Epitope mapping of imidazolium cations in ionic liquid-protein interactions unveils the balance between hydrophobicity and electrostatics towards protein destabilisation.

    PubMed

    Silva, Micael; Figueiredo, Angelo Miguel; Cabrita, Eurico J

    2014-11-14

    We investigated imidazolium-based ionic liquid (IL) interactions with human serum albumin (HSA) to discern the level of cation interactions towards protein stability. STD-NMR spectroscopy was used to observe the imidazolium IL protons involved in direct binding and to identify the interactions responsible for changes in Tm as accessed by differential scanning calorimetry (DSC). Cations influence protein stability less than anions but still significantly. It was found that longer alkyl side chains of imidazolium-based ILs (more hydrophobic) are associated with a higher destabilisation effect on HSA than short-alkyl groups (less hydrophobic). The reason for such destabilisation lies on the increased surface contact area of the cation with the protein, particularly on the hydrophobic contacts promoted by the terminus of the alkyl chain. The relevance of the hydrophobic contacts is clearly demonstrated by the introduction of a polar moiety in the alkyl chain: a methoxy or alcohol group. Such structural modification reduces the degree of hydrophobic contacts with HSA explaining the lesser extent of protein destabilisation when compared to longer alkyl side chain groups: above [C2mim](+). Competition STD-NMR experiments using [C2mim](+), [C4mim](+) and [C2OHmim](+) also validate the importance of the hydrophobic interactions. The combined effect of cation and anion interactions was explored using (35)Cl NMR. Such experiments show that the nature of the cation has no influence on the anion-protein contacts, still the nature of the anion modulates the cation-protein interaction. Herein we propose that more destabilising anions are likely to be a result of a partial contribution from the cation as a direct consequence of the different levels of interaction (cation-anion pair and cation-protein).

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

    PubMed

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

    2010-01-19

    Clean energy production has become one of the most prominent global issues of the early 21st century, prompting social, economic, and scientific debates regarding energy usage, energy sources, and sustainable energy strategies. The reduction of greenhouse gas emissions, specifically carbon dioxide (CO(2)), figures prominently in the discussions on the future of global energy policy. Billions of tons of annual CO(2) emissions are the direct result of fossil fuel combustion to generate electricity. Producing clean energy from abundant sources such as coal will require a massive infrastructure and highly efficient capture technologies to curb CO(2) emissions. Current technologies for CO(2) removal from other gases, such as those used in natural gas sweetening, are also capable of capturing CO(2) from power plant emissions. Aqueous amine processes are found in the vast majority of natural gas sweetening operations in the United States. However, conventional aqueous amine processes are highly energy intensive; their implementation for postcombustion CO(2) capture from power plant emissions would drastically cut plant output and efficiency. Membranes, another technology used in natural gas sweetening, have been proposed as an alternative mechanism for CO(2) capture from flue gas. Although membranes offer a potentially less energy-intensive approach, their development and industrial implementation lags far behind that of amine processes. Thus, to minimize the impact of postcombustion CO(2) capture on the economics of energy production, advances are needed in both of these areas. In this Account, we review our recent research devoted to absorptive processes and membranes. Specifically, we have explored the use of room-temperature ionic liquids (RTILs) in absorptive and membrane technologies for CO(2) capture. RTILs present a highly versatile and tunable platform for the development of new processes and materials aimed at the capture of CO(2) from power plant flue gas and

  7. The Effect of the Methylation and N-H Acidic Group on the Physicochemical Properties of Imidazolium-Based Ionic Liquids

    PubMed Central

    Rodrigues, Ana S.M.C.; Rocha, Marisa A. A.; Almeida, Hugo F. D.; Neves, Catarina M. S. S.; Lopes-da-Silva, José A.; Freire, Mara G.; Coutinho, João A. P.; Santos, Luís M. N. B. F.

    2017-01-01

    This work presents and highlights the differentiation of the physicochemical properties of the [C1Him][NTf2], [C2Him][NTf2], [1C12C1Him][NTf2], and [1C42C13C1im][NTf2] that are related with the strong bulk interaction potential, which highlights the differentiation on the physicochemical arising from the presence of the acidic group (N-H) as well as the methylation in position 2 (C(2)) of the imidazolium ring. Densities, viscosities, refractive indices and surface tensions in a wide range of temperatures, as well as, isobaric heat capacities at 298.15 K, for this IL series are presented and discussed. It was found that the volumetric properties are barely affected by the geometric and structural isomerization, following a quite regular trend. A linear correlation between the glass transition temperature, Tg, and the alkyl chain size was found; however, ILs with the acidic N-H group present a significant higher Tg than the [1CN-13C1im][NTf2] and [1CN3CNim][NTf2] series. It was found that the most viscous ILs, ([1C1Him][NTf2], [1C2Him][NTf2] and [1C12C1Him][NTf2]) have an acidic N-H group in the imidazolium ring in agreement with the observed increase of energy barrier of flow. The methylation in position 2, C(2), as well as, the N-H acidic group in the imidazolium ring, contribute to a significant variation in the cation-anion interactions and their dynamics, which is reflected in their charge distribution and polarizability leading to a significant differentiation of the refractive indices, surface tension and heat capacities. The observed differentiation of the physicochemical properties of the [1C1Him][NTf2], [1C2Him][NTf2], [1C12C1Him][NTf2], and [1C42C13C1im][NTf2] are an indication of the stronger bulk interaction potential, which highlights the effect that arises from the presence of the acidic group (N-H) as well as the methylation in position 2 of the imidazolium ring. PMID:26082427

  8. Anticholinesterase therapeutics. Preparation and in vivo evaluation of side-chain substituted quaternary imidazolium salts as pretreatment agents for organophosphonate intoxication

    SciTech Connect

    Harris, R.N.; Koolpe, G.A.; Sanderson, R.A.; Musallam, H.A.; Engle, R.R.

    1993-05-13

    Several quaternary imidazolium salts of the general formula 1 below, with R = CH3 or CH=NOH, n = 1 or 2, and X = sulfonamide, sulfamide, amide, urea, carbamate, or phosphonamide substituent were prepared, characterized, and evaluated intramuscularly in the mouse as pretreatment agents for protection against soman. Many of the compounds exhibited activity that was comparable to or better than pyridostigmine in the 15- to 60-minute pretreatment regimen indicating a rapid onset of protection. The analog of 1 with X = (N,N-dimethylamino)carbonyloxy provided significant protection at the 120 min time point distinguishing this substituent from the others and identifying it for further study.

  9. Expedient syntheses of the N-heterocyclic carbene precursor imidazolium salts IPr·HCl, IMes·HCl and IXy·HCl

    PubMed Central

    Hintermann, Lukas

    2007-01-01

    The 1,3-diaryl-imidazolium chlorides IPr·HCl (aryl = 2,6-diisopropylphenyl), IMes·HCl (aryl = 2,4,6-trimethylphenyl) and IXy·HCl (aryl = 2,6-dimethylphenyl), precursors to widely used N-heterocyclic carbene (NHC) ligands and catalysts, were prepared in high yields (81%, 69% and 89%, respectively) by the reaction of 1,4-diaryl-1, 4-diazabutadienes, paraformaldehyde and chlorotrimethylsilane in dilute ethyl acetate solution. A reaction mechanism involving a 1,5-dipolar electrocyclization is proposed. PMID:17725838

  10. Specific heat anomaly in ferroelectric: Bis(imidazolium) pentachloroantimonate(III) (C3 N2 H5)2[SbCl5

    NASA Astrophysics Data System (ADS)

    Przesławski, J.; Piecha-Bisiorek, A.; Jakubas, R.

    2016-04-01

    Single crystals of ferroelectric bis(imidazolium) pentachloroantimonate(III) (C3N2H5)2 [SbCl5 ] have been grown and the heat capacity was measured by the use of AC calorimetric method. The temperature dependence of excess heat capacity and excess entropy in the ferroelectric phase can be described in the frame of the classical Landau-Devonshire theory of phase transitions. The results of experimental studies were analyzed and the α, γ and δ values of the Landau potential coefficients were calculated. The temperature dependence of the order parameter was also evaluated from the heat capacity data.

  11. Locker Room Maintenance Made Easy.

    ERIC Educational Resources Information Center

    Theel, James

    1998-01-01

    Provides examples on ways to make locker room maintenance easier and their use more student-friendly. Improvements include use of indoor-outdoor carpeting with numerous floor drains to cut mildew buildup, adequate ventilation to reduce musty smells, better hot water management, ceramic tiles to reduce water-damage repair and painting needs, and…

  12. Locker Rooms: The Durable Design.

    ERIC Educational Resources Information Center

    Viklund, Roy; Coons, John

    1997-01-01

    Offers advice on heavy-use locker-room design that provides easier maintenance and vandal resistance. Design features and materials used for flooring, ceilings, and walls are addressed as are built-in systems and equipment, toilet and shower fixtures and partitions, lockers, and mechanical and electrical systems. (GR)

  13. Hotels Make Room for Fitness.

    ERIC Educational Resources Information Center

    Koszuta, Laurie Einstein

    1986-01-01

    Hotels, in hopes of gaining a competitive edge, are offering workout rooms, exercise equipment, fitness trails, and jogging tracks, but no standards have been set for safety of the facilities or staff preparedness in exercise screening, equipment use, injury prevention, or first aid. (MT)

  14. A Comparison of the Effects of Prenatal Exposure of CD-1 Mice to Three Imidazolium-Based Ionic Liquids

    PubMed Central

    Bailey, Melissa M.; Jernigan, Peter L.; Henson, Megan B.; Sturdivant, John; Rasco, Jane F.; Lovich, Ashley N.; Lockhard, Jarrett E.; Hough, Whitney; Di Bona, Kristin R.; Beaird, Janis; Sherrill, Jonathan; Swatloski, Richard P.; Rogers, Robin D.; Hood, Ronald D.

    2015-01-01

    BACKGROUND Ionic liquids (ILs; salts with melting points below 100 °C) exhibit wide liquid ranges, non-flammability, and thermal stability among other properties. These unique salts are best known as ‘green’ alternatives to traditional volatile organic solvents, which are utilized in both academia and industry. Our current study compares the developmental toxicity potential of three representative ionic liquids, with various chain lengths: 1-ethyl-3-methylimidazolium chloride ([C2mim]Cl), 1-butyl-3-methylimidazolium chloride ([C4mim]Cl), and 1-decyl-3methylimidazolium chloride ([C10mim]Cl). METHODS From gestation days (GD) 6-16, mated CD-1 mice were orally dosed with one of the following: 1000, 2000, or 3000 mg/kg/day [C2mim]Cl; 113, 169, or 225 mg/kg/day [C4mim]Cl; 50, 75, or 100 mg/kg/day [C10mim]Cl; or the vehicle only. Dams were sacrificed on GD 17, and their litters were examined for adverse effects. RESULTS Fetal weight was significantly decreased in the two highest dosage groups exposed to [C4mim]Cl and [C10mim]Cl in comparison with their controls, but the [C2mim]Cl treated groups were not affected. An apparent teratogenic effect was associated with both [C4mim]Cl and [C10mim]Cl, as the offspring exhibited certain uncommon morphological defects. However, the incidences of malformations were low and no correlation between incidence and dosage could be made. No morphological defects were observed in any of the [C2mim]Cl-treated groups, despite maternal morbidity at the highest dosage level. CONCLUSIONS This study indicates that [C4mim]Cl and [C10mim]Cl may have adverse effects on development at high maternal exposures and strongly supports the supposition that the toxicity of imidazolium-based ILs is influenced by alkyl chain length. PMID:20540104

  15. Systematic study of the thermophysical properties of imidazolium-based ionic liquids with cyano-functionalized anions.

    PubMed

    Neves, Catarina M S S; Kurnia, Kiki Adi; Coutinho, João A P; Marrucho, Isabel M; Lopes, José N Canongia; Freire, Mara G; Rebelo, Luís Paulo N

    2013-09-05

    In the past few years, ionic liquids (ILs) with cyano-functionalized anions have shown to be improved candidates for electrochemical and separation applications. Nevertheless, only scattered data exist hitherto and a broad analysis of their structure-property relationship has yet to be attempted. Therefore, in this work, a systematic study of the densities, viscosities and refractive indices of imidazolium-based ILs with cyano-functionalized anions was carried out at 0.1 MPa within a broad temperature range (from 278 to 363 K). The ILs under study are based on 1-alkyl-3-methylimidazolium cations (alkyl = ethyl, butyl and hexyl) combined with the [SCN](-), [N(CN)2](-), [C(CN)3](-) and [B(CN)4](-) anions. The selected matrix of cation/anion combinations allows us to provide a detailed and comprehensive investigation of the influence of the -CN group through an analysis of the thermophysical properties of the related ILs. The results show that, regardless of the cation, the densities decrease with an increase in the number of cyano groups or anion molecular weight. Moreover, for a fixed cation and temperature, the refractive index of the ILs decreases according to the rank: [SCN](-) > [N(CN)2](-) ≈ [C(CN)3](-) > [B(CN)4](-). On the other hand, no clear trend was observed for the viscosity of ILs and the respective number of -CN groups. The viscosity dependence on the cyano-functionalized anions decreases in the order: [SCN](-) > [B(CN)4](-) > [N(CN)2](-) > [C(CN)3](-). The isobaric thermal expansion coefficient, the derived molar refraction, the free volume, and the viscosity energy barrier of all compounds were estimated from the experimental data and are presented and discussed. Finally, group contribution models were applied, and new group contribution parameters are presented, extending these methods to the prediction of the ILs properties.

  16. Enantioselective oxidative stress caused by chiral ionic liquids forms of 1-alkyl-3-methyl imidazolium tartrate on Scenedesmus obliquus.

    PubMed

    Liu, Huijun; Wu, Jian; Zhang, Xiaoqiang; Xia, Yilu; Li, Yue; Du, Shaoting

    2017-10-01

    Ionic liquids (ILs) are widely used, but their potential threat to the environment has recently gained more attention. The enantioselective oxidative stress caused by chiral ionic liquids (CILs), such as 1-alkyl-3-methyl imidazolium tartrate (RMIM T), on Scenedesmus obliquus was demonstrated in this study. Stronger green fluorescence was observed in response to l-(+)-RMIM T treatment than to d-(+)-RMIM T treatment, which suggested that more reactive oxygen species (ROS) were stimulated by l-(+)-RMIM T. Significantly higher ROS levels were recorded during the RMIM T treatments than in the control. There were 1.13-, 1.25-, 1.43-, 1.68-, and 1.96-fold increases over levels in the control in the 3, 5, 10, 15, and 25mg/L d-(-)-HMIM T treatments, respectively, and 1.26-, 1.37-, 1.58-, 1.86- and 2.08-fold increases over levels in the control in the 3, 5, 10, 15, and 25mg/L l-(+)-HMIM T treatments, respectively. The total soluble protein content decreased as the RMIM T concentration increased. The SOD and CAT activities were stimulated at lower concentrations, but were inhibited at higher concentrations. Regression analysis implied that ROS is the major factor responsible for the oxidative damage caused by RMIM T. The ultrastructural morphology analysis showed that plasmolysis and damage to the chloroplasts, starch granule decreases, and lipid granule increased, and pyrenoid and nucleoid damage had occurred. These results showed that enantioselective oxidative stress and oxidative damage were caused by d-(+)-RMIM T and l-(+)-RMIM T, and that l-(+)-RMIM T caused more damage than d-(+)-RMIM T. Copyright © 2017 Elsevier B.V. All rights reserved.

  17. Facile one-pot preparation of a novel imidazolium-based monolith by thiol-ene click chemistry for capillary liquid chromatography.

    PubMed

    Zhang, Peng; Yang, Haiguan; Chen, Tao; Qin, Yuemei; Ye, Fanggui

    2016-11-09

    In this work, a novel imidazolium-based monolith was fabricated through a simple route. With 1-vinyl-3-octadecylimidazolium bromide and ethylene dimethacrylate as monomers, pentaerythritol tetra-(3-mercaptopropionate) as crosslinker, AIBN as thermal initiator, the monolith was facilely fabricated by one-pot thiol-ene click chemistry. The influences of both the content of monomer/crosslinker and porogenic systems on the morphology, and permeability of the monolith were studied. The optimal reaction conditions were used to prepare a homogeneous and permeable monolith. The optimal preparation of monolithic column was characterized by scanning electron microscopy, Fourier transform infrared spectrometry, X-ray photoelectron spectroscopy, and thermogravimetric analysis. High efficiency and quick separation of alkylbenzenes, styrene and ethylbenzene, polycyclic aromatic hydrocarbon, phenols, anilines, and aromatic acids were achieved. The minimum plate height of this monolith were determined as 11.42 μm for thiourea and 13.26 μm for benzene. All results indicated that thiol-ene click chemistry provides a quick way for the fabrication of imidazolium-based monolith.

  18. Alkyl-imidazolium based organosilica supported Fe/porphyrin complex: As novel, highly efficient and reusable catalyst for the unsymmetrical Hantzsch reaction.

    PubMed

    Elhamifar, Dawood; Badin, Parvin; Karimipoor, Gholamreza

    2017-08-01

    A noble alkyl-imidazolium ionic liquid based organosilica supported Fe/meso-tetrakis(4-sulfonatophenyl)porphyrin complex (ILOS@Fe/TSPP) is prepared, characterized and its catalytic efficiency is studied in the unsymmetrical Hantzsch reaction. The ILOS@Fe/TSPP was prepared by hydrolysis and co-condensation of 1,3-bis(3-trimethoxysilylpropyl)imidazolium chloride under acidic conditions followed by treatment with Fe/meso-tetrakis(4-sulfonatophenyl)porphyrin complex at ambient temperature. The material was characterized with TGA, EDX, SEM, TEM, XRD and DRIFT analyses. The ILOS@Fe/TSPP was successfully applied as powerful catalyst in the Hantzsch reaction for the preparation of a set of different derivatives of polyhydroquinolines in high to excellent yields. This catalyst was recovered and reused several times without important decrease in its activity. Furthermore, compared to the classical studies, this study consistently demonstrated the advantages of low catalyst loading, free-solvent media, short reaction times and simple purification of products. Copyright © 2017 Elsevier Inc. All rights reserved.

  19. Toxicity of two imidazolium ionic liquids, [bmim][BF4] and [omim][BF4], to standard aquatic test organisms: Role of acetone in the induced toxicity.

    PubMed

    Tsarpali, Vasiliki; Dailianis, Stefanos

    2015-07-01

    The main goal of this study was to investigate the toxicity of the imidazolium-based ionic liquids (ILs), [bmim][BF4] (1-butyl-3-methylimidazolium tetrafluoroborate) and [omim][BF4] (1-octyl-3-methylimidazolium tetrafluoroborate), in battery of standard aquatic toxicity test organisms. Specifically, exposure of the algae Scenedesmus rubescens, crustaceans Thamnocephalus platyurus and Artemia franciscana, rotifers Brachionus calyciflorus and Brachionus plicatilis and bivalve Mytilus galloprovincialis to different concentrations of [bmim][BF4], [omim][BF4] and/or a binary mixture of [bmim][BF4]-[omim][BF4] (1:1) with or without acetone (carrier solvent), revealed that solvent can differentially mediate ILs' toxic profile. Acetone's ability to differentially affect ILs' cation's alkyl chain length, as well as the hydrolysis of [BF4(-)] anions was evident. Given that the toxic potency of the tested ILs seemed to be equal or even higher (in some cases) than those of conventional organic solvents, the present study revealed that the characterization of imidazolium-based ILs as "green solvents" should not be generalized, at least in case of their natural occurrence in mixtures with organic solvents, such as acetone. Copyright © 2015 Elsevier Inc. All rights reserved.

  20. Imidazolium-Functionalized Poly(arylene ether sulfone) Anion-Exchange Membranes Densely Grafted with Flexible Side Chains for Fuel Cells.

    PubMed

    Guo, Dong; Lai, Ao Nan; Lin, Chen Xiao; Zhang, Qiu Gen; Zhu, Ai Mei; Liu, Qing Lin

    2016-09-28

    With the intention of optimizing the performance of anion-exchange membranes (AEMs), a set of imidazolium-functionalized poly(arylene ether sulfone)s with densely distributed long flexible aliphatic side chains were synthesized. The membranes made from the as-synthesized polymers are robust, transparent, and endowed with microphase segregation capability. The ionic exchange capacity (IEC), hydroxide conductivity, water uptake, thermal stability, and alkaline resistance of the AEMs were evaluated in detail for fuel cell applications. Morphological observation with the use of atomic force microscopy and small-angle X-ray scattering reveals that the combination of high-local-density-type and side-chain-type architectures induces distinguished nanophase separation in the AEMs. The as-prepared membranes have advantages in effective water management and ionic conductivity over traditional main-chain polymers. Typically, the conductivity and IEC were in the ranges of 57.3-112.5 mS cm(-1) and 1.35-1.84 mequiv g(-1) at 80 °C, respectively. Furthermore, the membranes exhibit good thermal and alkaline stability and achieve a peak power density of 114.5 mW cm(-2) at a current density of 250.1 mA cm(-2). Therefore, the present polymers containing clustered flexible pendent aliphatic imidazolium promise to be attractive AEM materials for fuel cells.