Showing papers on "Ionic liquid published in 1994"

Evidence for hydrogen bonding in solutions of 1-ethyl-3-methylimidazolium halides, and its implications for room-temperature halogenoaluminate(III) ionic liquids

Abstract: Multinuclear NMR spectroscopy and conductivity measurements showed that the 1-ethyl-3-methyl-imidazolium cation, [emim]+, not only forms strong hydrogen bonds (using all three ring protons H2, H4 and H5) with halide ions in polar molecular solvents (e.g. ethanenitrile) and ionic liquids, but that it exists in a quasi-molecular state, [emim]X, in non-polar solvents (e.g. trichloro- and dichloro-methane), showing a conventional aromatic stacking phenomenon.

Cooperative Spin Transitions in Iron(II) Derivatives of 1,2,4-Triazole

Abstract: Complexes of stoichiometry Fe( trzH )2( trz )X, where trzH is 1,2,4-triazole and X = BF4, ClO4, PF6, have been prepared. All three salts display temperature-induced singlet (1A1) ↔ quintet (5T2) transitions which are generally discontinuous and associated with a broad hysteresis loop. The salts are strongly thermochromic, being white above and pink-lilac below the transition region. Several samples of each salt were obtained and the detailed behaviour varied somewhat from one sample to another. For the fluoroborate and perchlorate salts the transition is centred above room temperature while for the hexafluorophosphate salt it occurs below room temperature. The perchlorate salt was also isolated in a form which showed a continuous transition but the nature of its electronic properties changed as the sample aged. In one form of the hexafluorophosphate salt the hysteresis loop spans room temperature and it has been possible to characterize both the singlet and the quintet state species at that temperature. For all three salts the transition has been characterized by measurement of the temperature dependence of the magnetism and Mossbauer and electronic spectra. These measurements establish that the complexes all contain an FeN6 coordination core and this must be achieved through bridging of the triazole units.

X-ray diffraction analysis of ionic liquids

Abstract: X-ray diffraction analysis of liquids halides melts oxyanion melts miscellaneous melts oxides. Appendix: Digital data of Qi(Q) and G(r).

Ion complex type of novel chiral smectic C* liquid crystal having chiral hydrogentartrate counterion

Abstract: A chirally ionic liquid crystal (ICLC) was prepared by the complexation of L(+)-tartaric acid and an achiral mesogenic group (NLC) with an amine unit, and its liquid crystalline behavior was examined by DSC, polarizing microscopy, and X-ray techniques. Ionic ICLC formed smectic A and chiral smectic C* phases. Due to an ionic aggregation, ionic ICLC exhibited a higher mesomorphic-isotropic phase transition temperature when compared to nonionic NLC.

Densities, molar volumes, and thermal expansivities of 1-methyl-3-ethylimidazolium chloride + aluminum chloride + alkali-metal halide molten salts

Abstract: Density measurements are reported for 1-methyl-3-ethylimidazolium chloride + AlCl[sub 3] binary melts and for 1-methyl-3-ethylimidazolium chloride + AlCl[sub 3] + MX ternary melts, where M = Li, Na, K, Rb, or Cs and X = Cl, Br, or 1 in the temperature range 15--105 C. From these measurements molar volumes and thermal expansion coefficients were calculated. The behavior of these properties is explained by the formation of complex tetrachloro- and heptachloroaluminates in these ionic liquids and by the radii of the alkali-metal cations and halide anions. The binary and ternary melts mix ideally with respect to volume. The effective ionic radius of the 1-methyl-3-ethylimidazolium cation increases with the molar fraction of AlCl[sub 3] in the binary melt.

The Ternary HCl : ImCl : AlCl3 Ambient‐Temperature Molten Salt System Expansion of the Electrochemical Window on Proton Addition to a Weakly Basic Ionic Liquid

Abstract: The addition of 1 eq of HCl (relative to available chloride) to a 49:51 AlCl 3 :lmCl (lm + ≡1-ethyl-3-methyl-1H-imidazolium)ionic liquid results in expansion of the electrochemical window of the melt to that more characteristic of a Lewis neutral melt. This is owing to the activity of H 2 Cl 3 - or HAlCl 5 - which, being weak Lewis acids in nature, serve to maintain a low chloride ion concentration. Voltammetric results suggest that several electroactive protic species are present

A review of liquid phase systems pertinent to diamond synthesis

Abstract: The evidence from nature and from a wide range of experiments clearly indicates several routes via liquid phases for the synthesis of diamond, graphite, and poorly crystallized carbons over a range of temperatures and pressures This review of the literature summarizes the following separate carbon-liquid regimes which are closely related to synthesis of various forms of carbon: (1) carbon as soot, carbon black, amorphous carbon, and graphite from C-H liquids derived from petroleum: (2) carbon from molten metal solvents including those containing hydrogen—especially the ideas proposed for solution/catalysis synthesis of diamond from different precursor carbons; (3) carbon from C-H-O liquids—primarily in natural systems—as evidenced by inclusions in quartz and diamond, coated diamond, diamond/graphite from metamorphic rocks and kimberlites, and poorly crystallized carbons from sedimentary rocks; (4) carbon from ionic liquids such as carbonates, silicates, and halides—both natural and synthetic Also considered are the possibility of connections among these categories

Evaluation of Ionic and Solvent Components of the Liquid-Junction Potential Between Aqueous and Several Aquo-Organic Solutions

Abstract: Values of Ej,ion, the ionic component of the liquid-junction potential Ej, were calculated for the HCl,H2O |HCl,S2 and KCl,H2O | KCl,S2 junctions, where S2 was EtOH-H2O, HCONMe2- H2O and Me2SO-H2O solvents, and for the AgNO3,H2O | AgNO3,MeCN-H2O junction, over the entire mixed-solvent ranges. Both the old approximate equation for Ej,ion and our improved equation, which accounts for the variation of the ionic transport numbers t and chemical potentials Go in the interphase region, were used. Significant differences between the two equations were observed for systems where the t and ΔtG° functions dnisplayed extrema against the mixed-solvent composition. The highest Ej,ion value was 395 mV, for the HCl,H2O | HCl,Me2SO junction. Values of Ej,s,the solvent component of Ej, were calculated by subtracting the corresponding Ej,ion values from the total Ej, which was evaluated in each case from the e.m.f , of a cell with the liquid junction of interest and the transfer activity coefficient of the electroactive ion, estimated by the tetraphenylborate assumption. The magnitude of Ej,s was significant for the junctions between H2O and most of the solvents, and was particularly large for those involving dipolar aprotic solvents and highly solvated ions. The maximum Ej,s value was -201 mV, observed for the junction HCl,H2O|HCl,100% Me2SO.

Lithium ionic conductive electrolyte

Abstract: PURPOSE: To provide a lithium conductive electrolytic substance having high conductivity at both room temperature and 100 deg.C by producing a glass formable mixture by mixing and heating two or more lithium salts and then cooling the mixture in vitreous state. CONSTITUTION: This lithium ion conductive electrolytic substance is a mixture of two or more lithium salts selected from a group of thiocyanate, iodide, bromide, chloride, nitrate, perchlorate, acetate, tetrafluoroborate, thiohalodialuminate, trifluoromethanesulfonate, haloaluminate, halodialuminate, and perfluoromethanesulfonamide. The mixture produces an ionic liquid. The electrolytic substance is produced by sufficiently heating the mixture and cooling the mixture to 100 deg.C or lower without causing crystallization.