Effect Of Imidazolium Ionic Liquids Research Articles

Structure effects of imidazolium ionic liquids on integrated CO2 absorption and transformation to dimethyl carbonate

The integration of chemical absorption of CO2 and in situ transformation to highly valuable chemicals is a promising process as an alternative toward fossil fuels. Here, three imidazolium ionic liquids (ILs), 1-butyl-3-methylimidazolium acetate, 1-butyl-3-methylimidazolium 1,2,4-triazole ([Bmim][Tz]), and 1-butyl-2,3-dimethylimidazolium 1,2,4-triazole were synthesized to absorb and activate CO2 by the formation of CO2-adducts, which can be in situ converted into dialkyl carbonates with alcohols (ROH, R = CH3, C2H5, and C4H9) in solvent diiodomethane under ambient temperature and pressure. The results show [Bmim][Tz] exhibits the best CO2 absorption capacity and dimethyl carbonates (DMC) yield, where CO2 capacity is up to 0.216 gCO2/gIL and DMC yield (based on methanol) is as high as 20.2 %. The structures of imidazolium ILs have significant effects on the absorption of CO2 and subsequent transformation process. Fourier transform infrared and carbon nuclear magnetic resonance spectroscopies demonstrate ILs structures influence binding sites for CO2 absorption, which can combine with CO2 to form CO2-adducts, zwitterion [Bmim-CO2], and [Tz-CO2]−. Furthermore, density functional theory calculations verify the structure effects (binding sites and steric hindrance) of ILs on the activation of CO2 and methanol, through the elongated CO bond lengths of CO2-adducts and O-H bond lengths of methanol in IL-methanol complexes, respectively, leading to different DMC yields. The integrated process is promising for the energy-efficient capture and utilization of CO2 under ambient conditions.

Effects of imidazolium ionic liquids on skin barrier lipids – Perspectives for drug delivery

Ionic liquids (ILs) have great potential to facilitate transdermal and topical drug delivery. Here, we investigated the mechanism of action of amphiphilic ILs 1-methyl-3-octylimidazolium bromide (C8MIM) and 3-dodecyl-1-methylimidazolium bromide (C12MIM) in skin barrier lipid models in comparison to their complex effects in human skin. C8MIM incorporated in a skin lipid model was a better permeation enhancer than C12MIM for water and model drugs, theophylline and diclofenac. Solid state 2H NMR and X-ray diffraction indicated that both ILs prefer the cholesterol-rich regions in skin lipids without significantly perturbing their lamellar arrangement and that C8MIM induces the formation of an isotropic lipid phase to a greater extent compared to C12MIM. C12MIM applied topically to the lipid model or human skin as a pretreatment was more potent than C8MIM. When co-applied with the drugs to human skin, aqueous C12MIM was more potent than C8MIM in enhancing theophylline permeation, but neither IL affected (even decreased) diclofenac permeation. Thus, the IL’s ability to permeabilize skin lipid barrier is strongly modulated by its ability to reach the site of action and its interactions with drug and solvent. Such an interplay is far from trivial and requires detailed investigation to realize the full potential of ILs.

Alkyl Chain Length Effects of Imidazolium Ionic Liquids on Electrical and Mechanical Performances of Polyacrylamide/Alginate-Based Hydrogels.

Conductive hydrogels with stretchable, flexible and wearable properties have made significant contributions in the area of modern electronics. The polyacrylamide/alginate hydrogels are one of the potential emerging materials for application in a diverse range of fields because of their high stretch and toughness. However, most researchers focus on the investigation of their mechanical and swelling behaviors, and the adhesion and effects of the ionic liquids on the conductivities of polyacrylamide/alginate hydrogels are much less explored. Herein, methacrylated lysine and different alkyl chain substituted imidazole-based monomers (IMCx, x = 2, 4, 6 and 8) were introduced to prepare a series of novel pAMAL-IMCx-Ca hydrogels. We systematically investigated their macroscopic and microscopic properties through tensile tests, electrochemical impedance spectra and scanning electron microscopy, as well as Fourier transform infrared spectroscopy, and demonstrated that an alkyl chain length of the IMCx plays an important role in the designing of hydrogel strain sensors. The experiment result shows that the hexyl chains of IMC6 can effectively entangle with LysMA through hydrophobic and electrostatic interactions, which significantly enhance the mechanical strength of the hydrogels. Furthermore, the different strain rates and the durability of the pAMAL-IMC6-Ca hydrogel were investigated and the relative resistance responses remain almost the same in both conditions, making it a potential candidate for wearable strain sensors.

Ionic Liquid Modified Electrochemical Capacitor with Long‐Term Performance

AbstractIonic liquids are used, for example, as corrosion inhibitors for metals, steel, and metal alloys. The method of preventing corrosion through the whole group of these kinds of compounds, called inhibitors, is to use them as additives to aggressive environments, including aqueous electrolytes. In this article, we present the inhibitive effect of imidazolium ionic liquids with 2,5‐dihydroxybenzenesulfonate anion on the corrosion of 316L stainless steel in neutral medium. In addition, we demonstrate that when the ionic liquid is used as an additive to the electrolyte solution (1 M Na2SO4) of a symmetric carbon/carbon electrochemical capacitor with 316L stainless‐steel current collectors, the capacitor lifetime is significantly extended. The ionic‐liquid additive inhibits corrosion of the current collector surface and, in effect, prevents activated carbon porous space from being blocked by corrosion products.

Effect of imidazolium ionic liquids as microwave absorption media for the intensification of microwave-assisted extraction of Citrus sinensis peel essential oils

Ionic liquid-based microwave-assisted extraction (MAE-IL) has been applied for the separation of essential oils (EOs) from Citrus sinensis var. Valencia peels. Two imidazolium ionic liquids, 1-ethyl-3-methyl imidazolium acetate ([C2mim]OAc) and 1-butyl-3-methyl imidazolium chloride ([C4mim]Cl), were investigated for extraction efficiency, thermal behavior of the process, and chemical composition of the EOs obtained. During extractions, two different concentrations of ionic liquids (ILs) were studied (5% or 10 %), and the proposed MAE-IL was evaluated in comparison with usual microwave-assisted extraction (MAE) using water as solvent. Results indicated that both concentrations of ILs influenced EO extraction, thermal behavior, and chemical composition. However, [C2mim]OAc was more efficient, increasing extraction velocity by 10 times, enhancing extraction efficiency of EOs (39 %), and increasing the presence of oxyterpene compounds in the EOs. However, the great ability of ILs to interact with microwaves had an impact on the thermal history of the sample, reaching almost 110 °C, promoting the presence of compounds related to thermal effect.

Enhancing Cerium Recovery from Leaching Solution of Glass Polishing Powder Waste Using Imidazolium Ionic Liquid

One of the high-tech industries is glass polishing, which is associated with the release of large volumes of wastewater, a rich source of rare-earth metals, especially cerium. In this study, cerium ion recovery from glass polishing powder waste using green solvents for extraction was investigated. Reaction time, temperature, organic to aqueous ratio, extractant concentrations, and the synergistic effects of imidazolium ionic liquids and trioctylphosphine oxide and tributylphosphate as extractants were optimized. The co-extraction of lanthanum, a significant problem in extracting cerium, was reduced by enhancement of their separation factor (~ 17). The cerium-bearing organic solvent was stripped with 0.5 mol/L HNO3 to attain a recovery of cerium by 99.98%. The ionic liquids are useful in the extraction process, enabling higher yields of cerium and reducing the consumption of acids in the stripping stage.

Determining mushroom tyrosinase inhibition by imidazolium ionic liquids: A spectroscopic and molecular docking study

The inhibition effects of imidazolium ionic liquids (ILs) on the enzyme kinetics of mushroom tyrosinase is reported. A simple UV-VIS spectrophotometric assay was used to measure the reaction kinetics of the reaction between mushroom tyrosinase and L-dopa. Seven different imidazolium ILs, comprised of 1-alkyl-3-methylimidazolium ([Imn1+], n=2, 4, 6) cations paired with several anions that included Cl−, [NO3−], methanesulfonate ([MeSO3−]), trifluoromethanesulfonate (or triflate, [TFMS−]), and bis(trifluoromethylsulfonyl)imide ([Tf2N−]). Lineweaver-Burk plots were generated from the recovered kcat and Km parameters using four to six substrate concentrations per measurement. The results show that mushroom tyrosinase activity was consistently inhibited by all of the ILs and that the type of inhibition was non-competitive in nearly all cases. Only the data for [Im21+][Tf2N−] suggested that the inhibition mechanism was competitive with the substrate. Molecular docking simulations were performed using AutoDock4.2 and AutoDock Vina and revealed that all cations docked in the L-dopa active site. Anions showed varied results that included locations both within and outside of the active site.

Imidozolium Ionic Liquids as Mobile Phase Additives in Reversed Phase Liquid Chromatography for the Analysis of Anions

An analytical method was developed for the simultaneous determination of bromide, thiosulfate, thiocyanate, hexafluorophosphate, trifluoroacetate and trifluoromethanesulfonate anions by reversed phase liquid chromatography with indirect ultraviolet detection using imidazolium ionic liquids as mobile phase additives. The effects of imidazolium ionic liquids, organic solvent, column temperature and detection wavelength on separation and detection of the anions were investigated and the mechanism was discussed, in which imidazolium ionic liquids acted as ion pair reagent and background ultraviolet absorption reagent of indirect ultraviolet detection. The suitable chromatographic conditions were methanol/0.5 mmol L−1 1-ethyl-3-methyl imidazolium tetrafluoroborate aqueous solution (10/90, v/v) as mobile phase, column temperature of 35 °C and flow rate of 1.0 mL min−1. The results indicated that the successful separation of the six anions within 10 min was achieved and the symmetry of peaks was satisfactory. Under these conditions, the detection limits of anions ranged from 0.02 to 0.52 mg L−1. Relative standard deviations for peak area and retention time were less than 0.24 and 0.46%, respectively. The method was applied to the determination of ionic liquid samples synthesized by chemistry laboratory. The results were accurate and reliable, and could meet the requirements for quantitative analysis.

Indirect ultraviolet detection of alkaline earth metal ions using an imidazolium ionic liquid as an ultraviolet absorption reagent in ion chromatography.

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 Mg2+ , Ca2+ , and Sr2+ 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 Mg2+ , Ca2+ , and Sr2+ 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 Mg2+ , Ca2+ , and Sr2+ within 14min were achieved using the selected chromatographic conditions, and the detection limits (S/N = 3) were 0.06, 0.12, and 0.23mg/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.

High Amorphous Vinyl Alcohol-Silica Bionanocomposites: Tuning Interface Interactions with Ionic Liquids

Herein, we demonstrate the effect of imidazolium ionic liquids (IL) applied as additives in the in situ formation of high amorphous vinyl alcohol (HAVOH)-silica bionanocomposites, using a simple sol–gel process approach. A complementary set of alkyl-, ether-, and carboxy-functionalized IL was used, allowing silica structure control and polymer–silica interphase tuning. Consequently, hybrids with diverse morphologies, as well as improved thermo-mechanical and barrier properties, were obtained. This diversity also highlighted the systems’ dependency on the IL’s molecular structure, where both the cation and anion influenced the hybrids’ final properties. This could be evidenced as the polar group functionalized-IL (ether- and carboxy-functionalized IL) allowed the formation of multiple hydrogen bonds at the organic–inorganic interphase, inducing a fine hybrid morphology with well-dispersed silica nanodomains. This significantly increased the storage (∼50%) and tensile moduli (∼20%), extensibility (up to 300...

Investigation of toxic effects of imidazolium ionic liquids, [bmim][BF4] and [omim][BF4], on marine mussel Mytilus galloprovincialis with or without the presence of conventional solvents, such as acetone

This study investigated the cytotoxic, oxidative and genotoxic effects of two commonly used imidazolium ionic liquids (ILs), [bmim][BF4] (1-butyl-3-methylimidazolium) and [omim][BF4] (1-methyl-3-octylimidazolium tetrafluoroborate), on the marine mussel Mytilus galloprovincialis, as well as whether acetone could mediate their toxic profile. In this context, mussels were firstly exposed to different concentrations of [bmim][BF4] or [omim][BF4], with or without the presence of acetone (at a final concentration of 0.06% v/v), for a period of 96h, in order to determine the concentration that causes 50% mussel mortality (LC50 values) in each case. Thereafter, mussels were exposed to sub- and non-lethal concentrations of ILs for investigating their ability to cause lysosomal membrane impairment (with the use of neutral red retention assay/NRRT), superoxide anion and lipid peroxidation byproduct (malondialdehyde/MDA) formation, as well as DNA damage and formation of nuclear abnormalities in hemocytes. The results showed that [omim][BF4] was more toxic than [bmim][BF4] in all cases, while the presence of acetone resulted in a slight attenuation of its toxicity. The different toxic behavior of ILs was further revealed by the significantly lower levels of NRRT values observed in [omim][BF4]-treated mussels, compared to those occurring in [bmim][BF4] in all cases. Similarly, [bmim][BF4]-mediated oxidative and genotoxic effects were observed only in the highest concentration tested (10mgL−1), while [omim][BF4]-mediated effects were enhanced at lower concentrations (0.01–0.05mgL−1). Overall, the present study showed that [bmim][BF4] and [omim][BF4] could induce not only lethal but also nonlethal effects on mussel M. galloprovincialis. The extent of [bmim][BF4] and/or [omim][BF4]-mediated effects could be ascribed to the length of each IL alkyl chain, as well as to their lipophilicity. Moreover, the role of acetone on the obtained toxic effects of the specific ILs was reported for the first time, giving evidence for its interaction with the ILs and the modulation of their toxicity.

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

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.

Effect of imidazolium ionic liquids on the hydrolytic activity of lipase

The effect of 1-alkyl-3-methylimidazolium ionic liquids (ILs) on the hydrolysis activityof Candida rugosa lipase (CRL) toward triacylglycerol was investigated. The critical micelle concentrations (CMC) of ILs with Br − , Cl − , and [BF 4 ] − anions and the solubility of ILs with [PF 6 ] − anions were determined in phosphate buffer. Results suggested that the content of the ILs, not kosmotropicity, highly influenced the effects of anions and cations of ILs on CRL activity. As the length of alkyl chain of the cation [C n MIM] + increased, lower IL content was required to achieve high enzyme activity. Once the concentrations of the ILs with Br − , Cl − , and [BF 4 ] − anions exceeded the CMC value, enzyme activity was suppressed. The positive promotion effect of anions on enzyme activity was in the order of Br − Cl − [BF 4 ] − [PF 6 ] − . The effect of ionic liquid on enzyme activity was highly dependent on the pH and temperature of the system, with the optimum pH being 7.000. Under optimal conditions of pH 7.000, 30 °C, and 47.6 mmol/L of [C 8 MIM]Br, the highest relative activity of CRL (1734%) was achieved, with a specific activity of 54.4 U/mg protein. 考察了1-烷基-3-甲基咪唑类离子液体对柱状假丝酵母脂肪酶(CRL)催化橄榄油水解反应活性的影响, 14;利用电导法确定了磷酸盐缓冲液中Br − , 14;Cl − , 14;[BF 4 ] − 系列咪唑离子液体的临界胶束浓度(CMC)和[PF 6 ] − 系列咪唑离子液体的溶解度. 结果显示, 14;离子液体的阴、阳离子对酶活性的影响规律与离子液体的Kosmotropicity性质无明显关联, 14;但与离子液体在体系中的含量密切相关, 14;在最适离子液体含量时, 14;酶活性达到最高; 阳离子[C n MIM] + 中的 n 越大, 14;可促进酶活性的离子液体适宜含量越低; Br − , 14;[BF 4 ] − 系列离子液体的浓度超过CMC时则抑制酶活; 阴离子对酶活性的最大促进作用顺序为Br − >Cl − >[BF 4 ] − >[PF 6 ] − . 离子液体对酶活性的影响随体系pH和温度的不同而改变, 14;在最适离子液体浓度时的最适pH均为7.000. 在pH 7.000, 14;30°C以及[C 8 MIM]Br离子液体浓度为47.6 mmol/L的最佳条件下, 14;最高相对酶活力和比活力分别达到1734%和54.4 U/mg protein. Lipase hydrolytic activity was strongly affected by the concentrations, cation structure and anion type of the ILs. The beneficial effect of the IL on lipase activity was eliminated as the IL approached its CMC.

Accelerating effect of imidazolium ionic liquids on the singlet oxygen promoted oxidation of thioethers: A theoretical study

A computational study of the catalytic activity exhibited by imidazolium based ionic liquids on the singlet oxygen promoted oxidation of thioethers is presented. The reaction of singlet oxygen with thioanisole and diethyl sulfide, in the absence and in the presence of 1-butyl-3-methylimidazolium cation, was followed along the reaction coordinate up to the formation of the persulfoxide intermediate that is widely recognized as the key intermediate in this process. In line with previous experimental observations, the results obtained show that the imidazolium cation strongly stabilizes the persulfoxide intermediate by hydrogen bonding thus depressing the unproductive intersystem crossing and favoring product formation. Evidence for a significant role played by exciplex intermediates in this reaction was also found. Surprisingly, the results for the singlet oxygen-sulfide system in the absence of imidazolium show that whereas diethyl sulfide can readily form the persulfoxide intermediate, from which S-oxidation products ensue, for thioanisole the persulfoxide formation is characterized by a high activation energy. A detailed investigation on the role played by the aromatic ring in this dramatic activation energy increase is presented suggesting, for the first time, a rationale for the well known low reactivity exhibited by aromatic sulfides in reactions with singlet oxygen.

Trypsin activity in imidazolium based ionic liquids: evaluation of free and immobilized enzyme

This work aimed the evaluation of ionic liquids as an alternative to conventional organic solvents in the enzymatic synthesis of peptides. For this, the effect of imidazolium ionic liquids on the activity and stability of immobilized trypsin was studied. Enzyme activity was studied by means of a model reaction, the hydrolysis of N-α-benzoyl-DL-arginine-p-nitroanilide (BAPNA), optimized by means of batch and flow methodologies. The activity of the enzyme was studied in strictly aqueous media and in the presence of increasing concentrations of emim [BF4], emim [Ms], emim [OTf] and bmim [BF4]. It was observed that bmim [BF4] seemed to be the less inhibiting IL, leading to a maximum enzyme inhibition of 69.3% when presented in a concentration of 85%, in the assays with free enzyme. The results were similar on both batch and flow assays. Moreover, an enhanced catalytic efficiency of immobilized trypsin in IL media was observed when compared with that of free enzyme. These observations evidence the compatibility between ILs and the utilization of enzymes immobilized in glass beads. The results gathered from this work can be of most importance for the large-scale industrial implementation of the trypsin catalysed peptide synthesis since enzyme stabilization through immobilization showed to be adequate to high yield synthetic biotransformations in biphasic media (IL-water). There were no evidences of enzyme leakage from the glass beads during its continued use in ionic liquid media.The SIA methodologies showed to be interesting tools for the evaluation of trypsin's activity in ionic liquids as they proved to be robust and exhibited good repeatability in all the assay conditions leading also to a reduction of the consumption of solvents as well as of effluent production.

Cytotoxic Effects of Imidazolium Ionic Liquids on Fish and Human Cell Lines

Ionic liquids bring a promise of a wide range of "green" applications that could replace conventional volatile solvents. However, before these applications become large-scale, their toxicity needs to be investigated in order to predict the impact on human health and environment. In this study we assessed the cytotoxicity of imidazolium ionic liquids (in the concentrations between 0.1 mmol L-1 and 10 mmol L-1) in the ovarian fish cell line CCO and the human tumour cell line HeLa using the MTT cell viability assay. Our results showed that the most cytotoxic ionic liquid was 1-n-butyl-3-methylimidazolium bis(trifluoro methylsulphonyl)imide, [BMIM][Tf2N], followed by 1-n-butyl-3-methylimidazolium tetrafluoroborate [BMIM][BF4], 1-n-butyl-3-methylimidazolium hexafluorophosphate [BMIM][PF6], and 1,3-dimethylimidazolium hexafluorophosphate [MMIM][PF6]. Generally, the effects were concentration-dependent. They also depended on the type of anion and the n-alkyl chain length. The comparison between the fish CCO and human HeLa cell lines suggests that CCO cells provide a good biological system for initial toxicity testing of ionic liquids that could replace in vivo bioassays.

Influence of Imidazolium Ionic Liquids on Dehydrogenase Activity of Activated Sludge Microorganisms

Imidazolium salts are one of the most often used and investigated groups of ionic liquids (ILs). The research concerning their ecotoxicity comprised many test organisms representing different trophic levels; however, their impact on mixed cultures of microorganisms such as activated sludge has been hardly ever investigated. Thus, in this work, the effect of imidazolium ionic liquids on dehydrogenase activity of activated sludge was estimated. Three activated sludges of different properties and origin were tested. It occurred that 1-alkyl-3-methyl imidazolium bromides do not inhibit dehydrogenase activity of sludge, if the alkyl chain contains up to six carbon atoms. The values of IC50 for these ILs were above 100 mg l−1. At the same time, the inhibitory effect on dehydrogenase activity of activated sludge increases with the increase in chain length of the alkyl substituent. The degree of inhibition of dehydrogenase activity of sludge microorganisms is dependent on activated sludge properties.

Effects of Imidazolium Ionic Liquids on Growth, Photosynthetic Efficiency, and Cellular Components of the Diatoms Skeletonema marinoi and Phaeodactylum tricornutum

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.

The dramatic acceleration effect of imidazolium ionic liquids on electron transfer reactions

Imidazolium ionic liquids (ILs) exhibited a dramatic acceleration effect on the electron transfer from metal complexes such as (C(5)Me(5))(2)Fe(II) and (C(5)Me(5))(2)Co(II) to the oxygen molecule; this acceleration effect can be ascribed to the stabilization of the oxygen radical anions by coordinating with the acidic C2-H of imidazolium ILs.

Highly Selective Electrochemical Fluorination of Organic Compounds in Ionic Liquids

AbstractFor Abstract see ChemInform Abstract in Full Text.