IL Structure Research Articles

Ionic liquid effects on the redox potential of ferrocene

The ionic liquid, IL, dependence of the mid-point potential of the ferrocene|ferrocenium, Fc0/+, couple versus the decamethylferrocene|decamethylferrocenium, DmFc0/+, couple was studied in eleven ILs and in dichloromethane with added IL as the supporting electrolyte. The difference in mid-point potential between Fc and DmFc indicates that Fc0/+ couple is clearly dependent on the IL structure. A variation of about 0.100V over the range of ILs studied under neat conditions and by ca. 0.050V when studied in dichloromethane is reported. Meanwhile, a variable potential shift ranging from 0.014 to 0.082V was observed when data was compared in these two systems (ILs vs. dichloromethane). The effect of water and lithium ion on the Fc0/+ and DmFc0/+ redox potential was also evaluated and found to be minimal.

Long term stability of superoxide ion in piperidinium, pyrrolidinium and phosphonium cations-based ionic liquids and its utilization in the destruction of chlorobenzenes

Investigation of the chemical generation and long term stability of superoxide ion, O 2 · - , in three bis (trifluoromethylsulfonyl) imide [TFSI −] anion based ionic liquids, ILs, with cations of 1-(3-methoxypropyl)-1-methylpiperidinium [MOPMPip +], 1-hexyl-1-methyl-pyrrolidinium [HMPyrr +] and trihexyl (tetradecyl) phosphonium [P14,666 +] has been conducted. The chemical generation of O 2 · - in ILs was carried out by dissolving potassium superoxide, KO 2, in the corresponding IL, while electrochemical generation was carried out by reduction of O 2 to O 2 · - in ILs followed by analysis using cyclic voltammetry technique. It was found the solubility of KO 2 in the studied ILs depends on the structure of ILs in addition to the temperature. However, in all cases the solubility was high enough for many applications. The Long term stability of the generated O 2 · - was carried out by the application of KO 2 in aprotic solvent, dimethyl sulfoxide, in the presence of the corresponding IL. UV–visible spectrophotometry at an absorbance range of 190–400 nm was used to determine the stability of O 2 · - . It was found that ILs containing [MOPMPip +] and [HMPyrr +] cations offer a promising long term stability of O 2 · - for various reactions and applications, while consumption of O 2 · - in [P14,666 +][TFSI −] with a rate constant of 16.2 × 10 −5 s −1 indicates that the generated O 2 · - in this IL is not stable enough for practical applications. To our best knowledge this is the first time a piperidinium and pyrrolidinium based ILs were used as media for the chemical generation of O 2 · - . The chemically generated O 2 · - by dissolving KO 2 was then used for the destruction of chlorobenzenes in [MOPMPip +][TFSI −] and [HMPyrr +][TFSI −] at ambient conditions. This work presents the first attempt to use KO 2 for the destruction of chlorinated aromatic hydrocarbons in ILs media.

Microwave‐Assisted Derivatization of Cellulose, 2 – The Surprising Effect of the Structure of Ionic Liquids on the Dissolution and Acylation of the Biopolymer

AbstractThe relevance of the structure of ILs for the dissolution and microwave‐assisted acylation of eucalyptus cellulose is reported. The 1‐R‐3‐methylimizadolium‐X ILs with X = Cl, Ac and R = 1‐butyl, 2‐methoxyethyl, 1‐heptyl, and 3,6‐dioxa‐(1‐heptyl) are studied: C4MeImX, C3OMeImX, C7MeImX, and C5O2MeImX. The dissolution efficiencies are C3OMeImAc > C4MeImAc and C7MeImAc > C5O2MeImAc, i.e., they depend on the length of the side chain. This surprising result is corroborated by (i) cellulose acylation by ethanoic, butanoic, and hexanoic anhydride; (ii) the energy of viscous flow of the ILs; (iii) the solvatochromic properties of the ILs. Our results show that C3OMeImAc and C4MeImAc are distinct from C7MeImAc and C5O2MeImAc, due to chain‐dependent hydrogen bonding and hydrophobic interactions.

Supported ionic liquids in Burkholderia cepacia lipase-catalyzed asymmetric acylation

▶ The preparation of support/ionic liquid/lipase (SILE) catalysts is described. ▶ [EMIM][NTf 2 ] on Kynol™ ACC 507-15 active carbon cloth stabilizes Burkholderia cepacia lipase (lipase PS) against reuse and temperature. ▶ ACC 507-15/[EMIM][NTf 2 ]/lipase PS works enantioselectively on the acylation of secondary alcohols. Lipase PS from Burkholderia cepacia was successfully immobilized on Kynol™ ACC 507-15 active carbon cloth with and without ionic liquids as SILE catalysts. Activity, enantioselectivity and reuse of the catalysts were evaluated in the acylation of 1-phenylethanol with vinyl acetate in toluene and in hexane over the temperature range 25–60 °C. The presence of [EMIM][NTf 2 ] clearly stabilized the enzyme against inactivation and preserved enantioselectivity in reuse in a process which is affected by the nature of the IL, solvent and substrate structure.

ChemInform Abstract: Study on Rh(I)‐Catalyzed Cycloisomerization of Dienes with Alkenes in Ionic Liquids: Effects of the Structure of ILs on Catalyst Recyclability.

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

Toxicity of imidazolium and pyridinium based ionic liquids towards algae. Bacillaria paxillifer (a microphytobenthic diatom) and Geitlerinema amphibium (a microphytobenthic blue green alga)

Many studies done so far on the aquatic ecotoxicity of ionic liquids have dealt with phytoplankton organisms. Nonetheless, benthic organisms are just as important if we are to fully understand the prospective fate and effects of ionic liquids in the aquatic environment. An investigation was therefore undertaken into the toxicity of 1-alkyl-3-methylimidazolium ionic liquids towards the diatom Bacillaria paxillifer and the cyanobacteriumGeitlerinema amphibium, species characteristic of the benthic environment. As in the first part of this study (A. Latala, M. Nedzi and P. Stepnowski, Green Chem., 2009, 11, 580–588), five 1-alkyl-3-methylimidazolium chlorides (from ethyl to decyl) were chosen as the test kit compounds for examining the expected alkyl chain length effect, together with 1-butyl-3-methylimidazolium tetrafluoroborate, dicyanamide, trifluoromethanesulfonate and methyl sulfate and α-methyl[poly(oxy-1,2-ethanediyl)]sulfate for investigating the influence of anions on the toxicity of ionic liquids towards the algal species under investigation. A pronounced alkyl chain effect was found with both organisms. The results indicate that P. amphibium is more sensitive than B. paxillifer. It was also found that the use of trifluoromethanesulfonate and dicyanamide as counteranions in the IL structure gave rise to the most pronounced toxic effects in comparison with the other anions tested. It is assumed that the greater toxicities of long alkyl chain ILs will most probably not pose a greater threat to benthic organisms, since these compounds will undergo rapid and very strong adsorption to sedimentary matter. Short-chain compounds, which are known to be reversibly bound to sediments, may still pose a significant risk to benthic ecosystems, however.

Stability of the Infinite Layer Structure with Iron Square Planar Coordination

The recently discovered SrFeO2 prepared by a soft chemical route from a precursor SrFeO3 has the "infinite layer" (IL) structure with an unprecedented FeO4 square-planar coordination. We show that the IL structure has significant solubility to yield Sr1-xCaxFeO2 (0 <or= x <or= 1) and is thermally stable (at least as high as 1000 K for SrFeO2). These results demonstrate that the IL structure, once it is formed at low temperatures, is surprisingly robust owing to the extremely covalent nature of the Fe-O bond, thereby opening a door to chemical tuning of properties and to possible high-temperature applications.

Aqueous Biphasic Systems of Hydrophilic Ionic Liquids + Sucrose for Separation

In this work, we proposed a new aqueous biphasic system (ABS) composed of hydrophilic ionic liquids (ILs, namely, 1-allyl-3-methylimidazolium chloride, [Amim]Cl, 1-allyl-3-methylimidazolium bromide, [Amim]Br, and 1-butyl-3-methylimidazolium tetrafluoroborate, [Bmim]BF4) and sucrose, forming an upper IL-rich phase and a lower sucrose-rich phase. The effects of IL structure on the phase equilibrium were investigated. It was found that the formation of ABS could be promoted by the increase of the side-chain length of ILs, but the effect was weaker than that of the anion. On the basis of phase diagrams we described, it was concluded that the chaotropicity decreased in the order [Bmim]BF4 > [Amim]Br > [Amim]Cl. This is consistent with IL + salt systems with which they were compared; however, the proposed systems are more environmentally benign for separating ILs from the aqueous phase.

Molecular Dynamics Simulations of Ionic Liquids: Influence of Polarization on IL Structure and Ion Transport

ABSTRACTMany-body polarizable force field has been developed and validated for a wide class of ionic liquids. Classical molecular dynamics (MD) simulations have been performed on 29 ionic liquids. This presentation will focus on ability of developed force fields to predict condensed phase properties and on understanding the influence of many-body polarizable interactions on the ionic liquid structure and transport.

Solvation of Sodium Chloride in the 1-Butyl-3-methyl-imidazolium Bis(trifluoromethylsulfonyl)imide Ionic Liquid: A Molecular Dynamics Study

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.

Studies on low temperature structure of infinite-layered superconductor Sr 1− xLa xCuO 2 (0 ≤ x ≤ 0.12)

Low temperature structure was investigated on infinite-layered Sr 1− x La x CuO 2 (0 ≤ x ≤ 0.12, La-IL) superconductor by X-ray absorption fine structure (XAFS), X-ray diffraction (XRD) and Raman spectroscopy. XAFS showed that CuO bond distance slightly expanded with lowering temperature down to 20 K, and the expansion was remarkable below T c(onset) = 43 K. Tetragonal lattice parameters shrank with lowering temperature but the shrinkage of the a-parameter seemed to be almost saturated below T c(onset). Resonance Raman peaks were observed at 151 cm −1 and 304 cm −1 in the La-doped samples, although the ideal IL structure should be Raman inactive. The peak intensities increased with lowering temperature. The variation may be related to the change observed with both XAFS and XRD in local structure with temperature. It is assumed that the CuO 2 plane may buckle with shifting oxygen ion positions above and below the CuO 2 plane, as reported in another electron-doped superconductor Nd 2− x Ce x CuO 4 (T′-214).

Growth of CaCuO2and SrxCa1 –xCuO2epitaxial films on NdGaO3substrates by pulsed laser deposition

High quality epitaxial films of the ‘infinite layer’(IL) compound SrxCa1 –xCuO2(x= 0–1) have been grown by pulsed laser deposition on NdGaO3(110) substrates, thus including the last member of this series CaCuO2, for the first time, to our knowledge. The quality of films varied with the composition: higher quality films were obtained for x= 0 and 0.1. The experimental results have been explained by taking into account the lattice match between film and substrate: a better match results in a better film quality. A very good match is obtained on NdGaO3 substrates for IL films with small or zero Sr content. Attempts to grow IL films were also carried out on SrTiO3 and LaAlO3 substrates. On SrTiO3 substrates it was not possible to grow IL films in the absence of Sr, while on LaAlO3 substrates no IL films could be grown at all. In the case of SrTiO3, the lattice match is good only for Sr-rich films, while in the case of LaAlO3, no good match can be obtained for any composition. Such substrate effects are not unexpected due to the importance of the substrate for the pseudomorphic stabilization of the otherwise unstable IL structure.

Molecular evolution of interleukin-3

Chimpanzee, tamarin, and marmoset interleukin-3 (IL-3) genes were cloned, sequenced, and expressed. Western blot analysis demonstrated that functional genes were isolated. IL-3 sequences were compared with those of mouse, rat, rhesus monkey, gibbon, and man. Multiple alignment of the IL-3 coding regions showed that only a few regions had been conserved during mammalian evolution, which are likely associated with functional domains of the IL-3 protein. Substitution rates for the various lineages were calculated and the numbers of synonymous and nonsynonymous substitutions were estimated separately. Distance matrices of the IL-3 coding regions were used to construct phylogenetic trees which revealed large differences in IL-3 evolution rate as well as a more rapid substitution rate for rodents and a rate slowdown during hominoid evolution. Extremes were rhesus monkey IL-3, which accumulated few synonymous substitutions, and gibbon IL-3, which had almost exclusively synonymous substitutions. In rhesus monkey IL-3, nonsynonymous substitutions outnumbered synonymous substitutions, which could not be readily explained by a random process of substitutions. We assume that during evolution of IL-3, the majority of the amino acid replacements and the impaired interspecies functional cross-reactivity originate from selection mechanisms with the most likely selective force being the structure of the heterodimeric IL.3 cell-surface receptor. Insight into IL-3 architecture and structural analysis of the IL-3 receptor are needed to analyze the unusually fast evolution of IL-3 in more detail.

Crystallization of Recombinant Human Interleukin–2

Recombinant human interleukin–2 (IL–2) was crystallized from a mixture of dilute ammonium acetate buffer (pH 5.0) and saturated sodium chloride solution. These crystals should provide the foundation for the X–ray analysis of the three dimension al structure of IL–2.