Alkylimidazolium Ionic Liquids Research Articles

High-sensitivity liquid chromatography-tandem mass spectrometry quantitative for alkyl imidazolium ionic liquids in human serum: Advancing biomonitoring of human exposure concerns

Alkyl imidazolium ionic liquids (Cn[MIM]), initially heralded as eco-friendly green solvents for diverse industrial applications, have increasingly been recognized fortheir biodegradability challenges and multiple biotoxicity. Despite potential health risks, research into the effects of Cn[MIM] on human health remains scarce, particularly regarding their detection in biological serum samples. This study validated a matrix-matched calibration quantitative method that utilizes solid-phase extraction (SPE) coupled with ultrahigh-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS). The method was used to analyze the presence of 10 ionic liquids (ILs) with varying alkyl carbon chain lengths (C2–C12) across 300 human serum samples. Efficient separation was achieved using optimized SPE conditions and a BEH C18 column with an appropriate mobile phase. Results demonstrated a strong linear relationship (0.05–100 ng/mL; R2 = 0.995–0.999), with detection and quantification limits with detection and quantification limits ranging from 0.001 to 0.107 ng/mL and 0.003–0.355 ng/mL, respectively. Intraday and inter-day precisions were 0.85–6.99 % and 1.50–7.46 %, with recoveries between 82 and 113 %. The validated method detected C6MIM in 19 % of samples and C8MIM in 8.3 % of samples, with concentrations ranging from 0.02 to 111.70 μg/L and 0.09–16.99 μg/L, respectively, suggesting a potential risk of human exposure. This underscores the importance of robust detection methods in monitoring environmental and human health impacts of alkyl imidazolium compounds.

Effect of dispersants on the hydroxyapatite‐filled natural rubber biocomposites with enhanced functional properties

AbstractThe aim of this work was application of the hydroxyapatite (HAP) in various amounts by weight as a filler of natural rubber (NR) biocomposites. Innovatively, silanes, that is, (3‐aminopropyl)‐triethoxysilane (APTES) and bis[3‐(triethoxysilyl)propyl] tetrasulfide (TESPTS), surfactant, that is, cetyltrimethylammonium bromide (CTAB), and alkylimidazolium ionic liquids (ILs) with halide anions, that is, 1‐butyl‐3‐methylimidazolium chloride (BmiCl) and 1‐decyl‐3‐methylimidazolium bromide (DmiBr), were used to improve the dispersion of the HAP and curatives particles in the rubber matrix, and consequently the curing characteristics and properties of NR biocomposites. The influence of HAP and dispersants on the crosslink density, tensile properties, thermal stability, resistance to thermo‐oxidative aging, and ability to damp vibration of vulcanizates were investigated. It has been proven, that HAP can be efficiently used as a filler of NR biocomposites alternatively to commercial inactive or active fillers, for example, chalk, talc, or silica. The optimal HAP content is 30 phr. HAP did not detrimentally affect the curing characteristics of NR composites, crosslink density, and damping properties of the vulcanizates, while significantly raised their tensile strength, thermal stability, and resistance to thermo‐oxidative aging. Most importantly, CTAB and ILs considerably improved the dispersion of HAP and curatives particles in the NR matrix and consequently lowered the vulcanization temperature by approximately 25°C and enhanced by approximately 50% the crosslink density and tensile strength of the NR biocomposites.

Ionic Liquids as Potential Cleaning and Restoration Agents for Cellulosic Artefacts

This study explores the efficacy of 1-hexyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide and 1-hexyl-3-methylimidazolium chloride as cleaning agents for aged cellulosic artifacts. A 10% v/v acetone solution of these ionic liquids (ILs) effectively removes the brownish-yellow color of aged paper in a 10 min immersion treatment. Colorimetric analysis shows a remarkable increase in lightness (L*) by up to 40% and a decrease in red/brownish tones (b*) after IL treatment. The cleaning process also deacidifies the paper, shifting the pH to neutral-slightly basic levels and enhancing its long-term stability. Optimal pH outcomes are achieved, with ionic liquid consumption values of 0.4–0.6 g/g of paper. The FTIR analysis revealed structural changes in cellulose induced by the washing step, which is mainly due to the reorganization effect imparted by the ionic liquids. Furthermore, ILs mobilized degraded compounds and acidic species, aiding in their extraction during the restoration process. Mechanical testing indicated an enhancement in the overall tensile strength and strain at break values for IL-treated papers by up to 33%. This study demonstrates the multiple benefits of alkylimidazolium ionic liquids for preserving and restoring cultural heritage artifacts made of cellulosic materials.

Unveiling the molecular interactions between alkyl imidazolium ionic liquids and human serum albumin: Implications for toxicological significance

Alkyl imidazolium-based ionic liquids (ILs) are promising for diverse industrial applications; however, their growing prevalence has raised concerns regarding human exposure and potential health implications. A critical aspect to be clarified to address the adverse health effects associated with ILs exposure is their binding mode to human serum albumin (HSA). In this study, we delved into the binding interactions between three alkyl imidazolium ILs (1-hexyl-3-methyl-imidazolium (C6[MIM]), 1-ethyl-3-methyl-imidazolium chloride (C8[MIM]) and 1-decyl-3-methyl-imidazolium (C10[MIM]) and human serum albumins (HSAs) using a comprehensive approach encompassing molecular docking and multi-spectroscopy (UV–visible, Fluorescence, Circular Dichroism, FTIR). Furthermore, for the first time, we developed an ultra-performance liquid chromatography–tandem mass spectrometry (UPLC-MS/MS) approach time to quantify plasma protein binding rates. Our results revealed that the ILs primarily bind to the hydrophobic cavity of HSA through hydrogen bonding and van der Waals forces, forming stable complexes via static quenching. This affected HSA's secondary structure, reducing α-helical content, particularly around specific residues. Equilibrium dialysis and ultrafiltration coupled with UPLC-MS/MS analysis showed modest plasma protein binding rates (17.84%–31.85%) for the three ILs, with no significant influence from alkyl chain effects or concentration relationship. Lower plasma protein binding rates can affect bioavailability and distribution of ILs, potentially influencing their toxicity. These findings provide critical insights into the potential toxicological implications at the molecular level, thereby contributing to continuous efforts to evaluate the risk profiles and ensure the safe utilization of these compounds.

Photocatalytic degradation of alkyl imidazole ionic liquids by TiO2 nanospheres under simulated solar irradiation: Transformation behavior, DFT calculations and promoting effects of alkali and alkaline earth metal ions

In this study, TiO2 nanospheres prepared by the sol-gel method were found to efficiently catalyze the photodegradation of 1-butyl-2,3-dimethylimidazolium bromide salt ([BMMIm]Br) under simulated solar irradiation through the main attack of hydroxyl radicals (•OH). The promoting effect of alkali metal (Li+→Cs+) and alkaline earth metal ions (Mg2+→Ba2+) was particularly emphasized. In-situ EPR tests showed that the introduction of alkali and alkaline earth metal ions could enhance the formation of •OH thus leading to a 7%−30.3% increase in the degradation efficiency of. [BMMIm]+. Moreover, the removal efficiency of [BMMIm]+ still reached > 96.19% in four real waters. A total of 23 products of [BMMIm]Br were detected, and hydroxyl substitution, bond breaking, direct oxidation and ring opening were considered as the main reactions during the photocatalytic degradation process. The results of toxicity evaluation showed that hydroxylation was a reaction process of increasing toxicity, while the bond breaking reaction had great detoxification capacity for [BMMIm]+. These findings may enhance our understanding on the effects of alkali or alkaline earth metal ions on the photocatalytic activity of TiO2, which could also provide reference for the efficient and green removal of alkylimidazolium ionic liquids in waters.

New Ionic Liquid Microemulsion-Mediated Synthesis of Silver Nanoparticles for Skin Bacterial Infection Treatments.

This work reports a new approach for the synthesis of extremely small monodispersed silver nanoparticles (AgNPs) (2.9-1.5) by reduction of silver nitrate in a new series of benzyl alkyl imidazolium ionic liquids (BAIILs)-based microemulsions (3a-f) as media and stabilizing agents. Interestingly, AgNPs isolated from the IILMEs bearing the bulkiest substituents (tert-butyl and n-butyl) (3f) displayed almost no nanoparticle agglomeration. In an in vitro antibacterial test against ESKAPE pathogens, all AgNPs-BAIILs had potent antibiotic activity, as reflected by antibacterial efficiency indices. Furthermore, when compared to other nanoparticles, these were the most effective in preventing biofilm formation by the tested bacterial strains. Moreover, the MTT assay was used to determine the cytotoxicity of novel AgNPs-BAIILs on healthy human skin fibroblast (HSF) cell lines. The MTT assay revealed that novel AgNPs-BAIILs showed no significant toxic effects on the healthy cells. Thus, the novel AgNPs-BAIILs microemulsions could be used as safe antibiotics for skin bacterial infection treatments. AgNPs isolated from BAIIL (3c) was found to be the most effective antibiotic of the nanoparticles examined.

Cyclic carbonate synthesis via cycloaddition of CO2 and epoxides catalysed by beta zeolites containing alkyl imidazolium ionic liquids used as structure-directing agents

Cyclic carbonates were synthesized via CO2 cycloaddition and epoxides, allyl-glycidyl-ether (AGE) and propylene oxide (PO), using hybrid materials formed by beta zeolites and ionic liquids, 1‑butyl‑3-methylimidazolium chloride (BMI.Cl) or 1-decyl-3-methylimidazolium chloride (DMI.Cl), as structure-directing agents which remained in their porosity. The beta zeolites, β-BMI.Cl and β-DMI.Cl, were used to convert AGE to AGC (allyl-glycidyl-carbonate), and β-BMI.Cl was also used to convert PO to PC (propylene carbonate). The optimal condition for β-BMI.Cl in which there was the total CO2 conversion was 50 bar pCO2 at 145 °C using AGE and 30 bar pCO2 at 130 °C using PO, being better than the catalyst β-DMI.Cl. The reuse of β-BMI.Cl led to a 95% yield of AGC after 5 h of reaction at 145 °C, showing the good stability of this catalytic system. The activation energy (Ea) of 97 kJ/mol was obtained through kinetic experiments conducted with AGE and β-BMI.Cl. Comparing experiments performed only with ionic liquids and hybrid materials, the last ones enabled the CO2 conversion with higher efficiency and were thermally more resistant. The results demonstrate that the β-BMI.Cl and β-DMI.Cl hybrid materials are promising catalytic systems to produce cyclic carbonates through CO2 conversion.

Surface active alkyl-imidazolium ionic liquids studied as templates to form vertically oriented pores in silica thin films

In this study, thin films of mesoporous silica with vertically oriented and hexagonally ordered pores have been synthetized and investigated. A variety of alkyl-imidazolium ionic liquids have been used as the template, with the aim to understand how changing the chain length on the imidazolium cation from hexadecyl (C16) to dodecyl (C12) or the protic character of the imidazolium head affects the film formation and the order of the pores. In addition, different types of metal substrates have been used for the film deposition, i.e. indium titanium oxide (ITO) and gold. Complementary experimental methods, including GISAXS, Infrared spectroscopy, and cyclic voltammetry have been employed for a thorough investigation of the morphology and permeability of the deposited thin films.

Tunable thermoresponsive UCST-type alkylimidazolium ionic liquids as a draw solution in the forward osmosis process

Recently, forward osmosis (FO) has been attracting attention as a new energy-saving water treatment technology. To put the FO process to practical use, it is indispensable to develop the optimum draw solution (DS) and construct its low energy regeneration process. In this study, various types of alkylimidazolium tetrafuluoroborate salts were synthesized, and their capabilities as novel thermoresponsive DSs for the FO desalination process were assessed using solution parameters such as phase diagram and osmotic pressure. The carbon number of a cation tunables the upper critical solution temperature (UCST)-point of alkylimidazolium-based ionic liquids' phase transition temperature. Considering the effect on the membrane material, the cooling temperature according to the climate, and the temperature range of low-grade waste heat in FO process, the ionic liquids having UCST points in the range of 25 °C to 50 °C, 1-pentyl-3-methylimidazolium tetrafluoroborate ([C5mim][BF4]), 1-pentyl-2,3-dimethylimidazolium tetrafluoroborate ([C5dmim][BF4]), 1-butyl-3-ethylimidazolium tetrafluoroborate ([C4eim][BF4]) and 1,3-dipropylidazolium tetrafluoroborate ([C3pim][BF4]), were judged to be suitable. The osmolalities of its water mixture varied with temperature, with a larger value at 50 °C than at 25 °C, with ILs with a lower UCST point exhibiting higher osmolality. The concentrated phase of [C4eim][BF4], which was phase-separated at 25 °C, had an osmotic pressure at 50 °C that was 1.6 times that of seawater, implying that it might be used as a DS in the FO seawater desalination process. Moreover, the osmolality at 25 °C dilutive phases of the [C5mim][BF4], [C5dmim][BF4], and [C4eim][BF4] aqueous solutions were all extremely low, these indicating that the osmotic resistance in the post-treatment membrane process can be minimized. The tunable thermoresponsive materials enabled a flexible process design, depending on the environmental and waste heat temperatures. Further, they can be used in various reaction solvents, extraction solvents, and other ingredients of the process.

Effect of the cation structure on the properties of homobaric imidazolium ionic liquids.

In this work we investigate the structure-property relationships in a series of alkylimidazolium ionic liquids with almost identical molecular weight. Using a combination of theoretical calculations and experimental measurements, we have shown that re-arranging the alkyl side chain or adding functional groups results in quite distinct features in the resultant ILs. The synthesised ILs, although structurally very similar, cover a wide spectrum of properties ranging from highly fluid, glass forming liquids to high melting point crystalline salts. Theoretical ab initio calculations provide insight on minimum energy orientations for the cations, which then are compared to experimental X-ray crystallography measurements to extract information on hydrogen bonding and to verify our understanding of the studied structures. Molecular dynamics simulations of the simplest (core) ionic liquids are used in order to help us interpret our experimental results and understand better why methylation of C2 position of the imidazolium ring results in ILs with such different properties compared to their non-methylated analogues.

Functionalized Imidazolium Bis(trifluoromethylsulfonyl)imide Ionic Liquids for Gas Sensors: Solubility of H2, O2 and SO2

Gas solubilities of non-polar (hydrogen and oxygen) and polar (sulphur dioxide) gases in a set of functionalized alkyl imidazolium ionic liquids with the bis(trifluoromethylsulfonyl)imide ([NTFf2]−) anion are reported between 303 and 333 K at 1 bar. The alkyl side-chains in the imidazolium cations include different functional groups, such as –OH, –CN and benzyl; their effects on gas solubilities were studied. The solubility decreases with temperature for all gases, as expected for an exothermic dissolution. Sulphur dioxide is by far the most soluble gas, with mole fractions between 0.29 and 0.41 in the ionic liquids at 313 K and 1 bar, approximately 2–3 orders of magnitude higher than the two other gases studied. Oxygen is generally more soluble in the ionic liquids than hydrogen with mole fractions ranging from 9 × 10−4 to 21 × 10−4 and 5 × 10−4 to 15 × 10−4 at 313 K and 1 bar for oxygen and hydrogen, respectively. In the case of hydrogen, the solubility increases when the molar volume of the ionic liquid increases, whereas for oxygen, the presence of polar groups in the cation causes a reduction in the solubility. None of the three gases is chemically absorbed in the ionic liquids.

Performance and Mechanism of Alkylimidazolium Ionic Liquids as Corrosion Inhibitors for Copper in Sulfuric Acid Solution.

The addition of corrosion inhibitors is an economic and environmental protection method to prevent the corrosion of copper. The adsorption, performance, and mechanism of three 1-alkyl-3-methylimidazolium hydrogen sulfate ([BMIM]HSO4, [HMIM]HSO4, and [OMIM]HSO4) ionic liquids (ILs) on the copper surface in 0.5 M H2SO4 solutions were studied by quantum chemical calculation, quantitative structure-activity relationship (QSAR), and molecular dynamics simulation. It is found that the main reactive site is located on the imidazolium ring (especially the C2, N4, and N7 groups). When the alkyl chain of the imidazolium ring is increasing, the molecular reactivity of the ILs and the interaction between the ILs inhibitor and copper surface are enhanced. The imidazole ring of the ILs tends to be adsorbed on Cu (111) surface in parallel through physical adsorption. The order of adsorption energy is [Bmim]HSO4 < [Hmim]HSO4 < [OMIM]HSO4, which is in agreement with the experimental order of corrosion efficiency. On the imidazole ring, the interaction between the copper surface and the C atom is greater than that between the copper surface and the N atom. It is found that ILs addition can hinder the diffusion of corrosion particles, reduce the number density of corrosion particles and slow down the corrosion rate. The order of inhibition ability of three ILs is [Bmim]HSO4 < [Hmim]HSO4 < [OMIM]HSO4,which agree well with experimental results. A reliable QSAR correlation between the inhibition corrosion efficiency and molecular reactivity parameters of the ILs was established.

Alkylimidazolium ionic liquids for biofilm control: Experimental studies on controlling multispecies biofilms in natural waters

Biofilm associated problems and inherent resistance of biofilm-bacteria to antimicrobial agents drives the need for alternate agents with potent antibiofilm activities. Alkylimidazolium ionic liquids were reported as novel antimicrobial and antibiofilm agents for preventing single species biofilms. However, naturally occurring biofilms are multispecies in nature constituting diverse organisms and have high prevalence, significance in medical, industrial and ecological perspective. In this study, the effect of three alkylimidazolium ionic liquids ([CnMIM]+[X]−, n = 4, 12 and 16) were evaluated against formation of natural and multispecies biofilms in freshwater and seawater. In 96-well biofilm assays, [C4MIM][Cl] with –butyl alkyl group did not exert antibiofilm activity even at 500 µM. [C12MIM][I] with –dodecyl alkyl group showed antibiofilm activity at 32 and 250 µM, in natural freshwater and seawater, respectively. Among the tested ionic liquids, [C16MIM][Cl] with –hexadecyl group showed superior antibiofilm activity. Presence of [C16MIM][Cl] in freshwater and seawater, respectively, at 8 and 125 µM caused complete inhibition in biofilm formation. Among the tested compounds, only [C16MIM][Cl] showed biofilm dispersal activity on pre-formed biofilms. Biofilm dispersal was near complete at 125 and 250 µM for freshwater and seawater biofilms, respectively. Potent antimicrobial ionic liquid ([C16MIM][Cl]) was further evaluated for biofilm prevention under dynamic conditions in a laboratory scale recirculation system. Over a period of 12 d of operation, biofilm formation was retarded in the presence of 100 μM and 250 μM of [C16MIM][Cl], in freshwater and seawater, respectively. The results suggest that antimicrobial [C16MIM][Cl] may find potential application for preventing multispecies biofilms in cooling water systems.

Viscosity and Ionic Conductivity of Imidazolium based Ionic Liquids bearing Triiodide Anion

In the electrolyte application for dye sensitized solar cells, utilization of ionic liquids is getting the highlights to replace volatile organic solvent thanks to their low volatility, thermal and electrochemical stability. The iodide/triiodide redox electrolyte is the preferred choice for this application, hence numerous iodide-based ionic liquids have been explored and reported. On the contrary, the transport properties of triiodide based ionic liquid is often lack of reporting despite of having an equal influence on the overall viscosity and ionic conductivity of the electrolyte. In this study, three alkylimidazolium triiodide ionic liquids were synthesized from the respective alkylimidazolium iodide ionic liquids precursors and their physicochemical and conductivity properties are reported. 1H NMR analysis showed a slight shifting of position of the resonances of triiodide based alkylimidazolium ionic liquids as compared to their precursors due to less electronegativity nature of triiodide anion. The formation of triiodide-based imidazolium ILs have dramatically altered the transport properties in which the ionic liquids obtained are of low viscosity and high ionic conductivity.

Polar/apolar domains' dynamics in alkylimidazolium ionic liquids unveiled by the dual receiver NMR 1H and 19F relaxation experiment

The dual receiver 1H/19F inversion-recovery NMR method is applied to measure simultaneously the spin-lattice relaxation times, T1, of both cation and anion forming ionic liquid (ILs) materials. Two representative classes of ILs comprising 1-alkyl-3-methylimidazolium [CnMIm]+ (n = 2, 12) as cation and bis(trifluoromethylsulfonyl)imide [TFSI]− or tetrafluoroborate [BF4]− as anions have been considered. The experimental data, acquired on a wide range of temperature (278–333 K), have been analysed according to the Bloembergen, Purcell, and Pound model and provide the rotational dynamic parameters, such as the activation energy and the correlation time τc of the rotational segmental motion. The overall dynamic behaviour is dictated by the length of the alkyl chain and the capability of the anion to disrupt or stabilize the apolar domain structure.

Core–shell structured Fe3O4@SiO2-supported IL/[Mo6O19]: A novel and magnetically recoverable nanocatalyst for the preparation of biologically active dihydropyrimidinones

The synthesis and catalytic application of a novel magnetic silica-nanomaterial-supported ionic liquid/hexamolybdate (Fe3O4@SiO2-IL/[Mo6O19]) are reported. The Fe3O4@SiO2-IL/[Mo6O19] nanocatalyst was prepared through modification of magnetic Fe3O4@SiO2 nanoparticles with alkyl-imidazolium ionic liquids followed by treatment with hexamolybdate anions. The Fe3O4@SiO2-IL/[Mo6O19] was characterized using FTIR, EDX, TGA, SEM, TEM, PXRD, and VSM techniques. This nanocatalyst exhibited excellent activity in the one-pot synthesis of biologically active dihydropyrimidinones through the Biginelli reaction. Furthermore, this magnetically recoverable nanocatalyst could be reused at least seven times without a significant loss of efficiency.

Alkylimidazolium Ionic Liquids as Antifungal Alternatives: Antibiofilm Activity Against Candida albicans and Underlying Mechanism of Action.

Candida albicans is an opportunistic pathogen causes fungal infections that range from common skin infections to persistent infections through biofilm formation on tissues, implants and life threatening systemic infections. New antifungal agents or therapeutic methods are desired due to high incidence of infections and emergence of drug-resistant strains. The present study aimed to evaluate (i) the antifungal and antibiofilm activity of 1-alklyl-3-methyl imidazolium ionic liquids ([CnMIM]+[X]–, n = 4, 12 and 16) against Candida albicans ATCC 10231 and two clinical C. albicans strains and (ii) the mechanism of action of promising antifungal ionic liquid on C. albicans. Two of the tested compounds were identified as more effective in preventing growth and biofilm formation. These ionic liquid compounds with –dodecyl and –hexadecyl alkyl groups effectively prevented biofilm formation by fluconazole resistant C. albicans 10231 and two other clinical C. albicans strains. Although both the compounds caused viability loss in mature C. albicans biofilms, an ionic liquid with –hexadecyl group ([C16MIM]+[Cl]–) was more effective in dispersing mature biofilms. This promising ionic liquid compound ([C16MIM]+[Cl]–) was chosen for determining the underlying mode of action on C. albicans cells. Light microscopy showed that ionic liquid treatment led to a significant reduction in cell volume and length. Increased cell membrane permeability in the ionic liquid treated C. albicans cells was evident in propidium iodide staining. Leakage of intracellular material was evident in terms of increased absorbance of supernatant and release of potassium and calcium ions into extracellular medium. A decrease in ergosterol content was evident when C. albicans cells were cultured in the presence of antifungal ionic liquid. 2′,7′-Dichlorodihydrofluorescein acetate assay revealed reactive oxygen species generation and accumulation in C. albicans cells upon treatment with antifungal ionic liquid. The effect of antifungal ionic liquid on mitochondria was evident by decreased membrane potential (measured by Rhodamine 123 assay) and loss of metabolic activity (measured by MTT assay). This study demonstrated that imidazolium ionic liquid compound exert antifungal and antibiofilm activity by affecting various cellular processes. Thus, imidazolium ionic liquids represent a promising antifungal treatment strategy in lieu of resistance development to common antifungal drugs.

Thermodynamics and selectivity of separation based on activity coefficients at infinite dilution of various solutes in ionic liquid [DMIM][Tf2N

The activity coefficients at infinite dilution (γi∞) is an important thermodynamic parameter for ionic liquids. By analyzing and calculating them, the possibility of ionic liquids as extractants can be estimated. The infinite dilution activity coefficients of 32 kinds of organic solutes (eg. alkyl benzenes, acetonitrile, tetrahydrofuran, n-alkanes, ethyl acetate, etc.) in ionic liquid 1-decyl-3-methylimidazole bis (trifluoromethylsulfonyl)imide [DMIM][Tf2N] were measured by gas chromatography (GLC) at six temperatures: 313.15 K, 323.15 K, 333.15 K, 343.15 K, 353.15 K, 363.15 K. Calculated some basic thermodynamic parameters such as the partial molar excess enthalpies at infinite dilution (H-iE,∞) , Gibbs free energies (G-iE,∞) and entropies (TrefS-iE,∞) were calculated at a reference temperature Tref = 298.15 K. At 323.15 K, the selectivity (Sij∞) of n-hexane (i)/benzene (j), cyclohexane/benzene, and capacity factor (kj∞) at infinite dilution of benzene have been determined. The results were analyzed in comparison to literature data for alkylimidazolium ionic liquids with [Tf2N]−.

Antibiofouling potential of 1-alkyl-3-methylimidazolium ionic liquids: Studies against biofouling barnacle larvae

Development of novel and environmental-friendly antifouling compounds is desirable due to the ban on use of tributyltin and concerns on copper and co-biocides. In the current study, antimacrofouling effects of alkylimidazolium ionic liquids on Amphibalanus (=Balanus) reticulatus, a dominant fouling barnacle were assessed. The effect of three alkylimidazolium ionic liquids ([CnMIM]+[X]−, n = 4, 12 and 16) on survival, metamorphosis and settlement of barnacle larvae (nauplii and cypris) was determined in laboratory bioassays. Among the tested ionic liquids, [C12MIM][I] exhibited superior antibiofouling activity with a cypris mortality (LC50) and settlement inhibition (EC50) concentrations of 0.35 μM and 0.39 nM, respectively. [C16MIM][Cl] showed moderate activity with LC50 and EC50 values of 0.63 μM and 1.56 nM, respectively. However, [C4MIM][Cl] exhibited lowest activity on survival and settlement with LC50 and EC50 values of 2.28 μM and 80.2 nM, respectively. The anion (Cl− or I−) did not contribute to the biological activity of ionic liquids. Antifouling activity of the tested ionic liquids on larvae decreased in the following order: [C12MIM][I] > [C16MIM][Cl] > [C4MIM][Cl]. Therapeutic ratios (TR = LC50/EC50) of the tested compounds at >28 to 900 were found to be much higher than the reference value (>15) qualifying them as promising non-toxic or environmentally benign antifoulants. Tested ionic liquids exhibited activity in the similar order ([C12MIM][I] > [C16MIM][Cl] > [C4MIM][Cl]) on survival and metamorphosis of nauplius larvae. EC50 and LC50 concentrations of all the three compounds had no lethal effect on non-target organism, Artemia salina. These data presents possibilities for designing effective and environmental friendly antifouling strategies.

Tribological properties of spherical and mesoporous NiAl particles as ionic liquid additives

In this study, spherical and mesoporous NiAl particles (abbreviated as sNiAl and mNiAl) were introduced as lubricant additives into two alkyl-imidazolium ionic liquids (ILs) (1-butyl-3-methylimidazolium tetrafluoroborate (LB104) and 1-butyl-3-methyl imidazolium hexafluorophosphate (LP104)) to explore their tribological properties. The sNiAl and mNiAl particles were modified in-situ by anion and cation moieties of ILs through chemical interaction, thereby enhancing their dispersibility and stability in ILs. The mNiAl particles have better dispersibility than the sNiAl ones in ILs because of high specific surface area. LP104-modified sNiAl particles show better friction reduction and wear resistance, mainly relying on the synergy of the hybrid lubricant. These particles form a protective layer that prevents friction pairs from straight asperity contact and improves the tribological behaviors.