Imidazolium Ionic Liquids Research Articles

Impact of emerging pollutants mixtures on marine and brackish phytoplankton: diatom Phaeodactylum tricornutum and cyanobacterium Microcystis aeruginosa

Pharmaceuticals and ionic liquids (ILs) are emerging as significant micropollutants with environmental presence and potential ecological impacts. The possible simultaneous occurrence of these two groups of pollutants in aquatic environments raises complex challenges due to their diverse chemical properties and potential for interactive effects. Given the documented widespread presence of pharmaceuticals and the emerging concerns about ILs, the study aims to evaluate the adverse effects of binary mixtures of imidazolium ionic liquid IM1-8C(CN)3 and two representatives of pharmaceuticals: antibiotic oxytetracycline (OXTC) and metabolite carbamazepine 10,11 epoxide (CBZ-E) on the brackish cyanobacterium Microcystis aeruginosa and the marine diatom Phaeodactylum tricornutum during chronic exposure experiments. A comprehensive approach was employed, incorporating various endpoints including oxidative stress, chlorophyll a fluorescence, detailed photoprotective and photosynthetic pigment profiles of target microorganisms to assess modes of action and identify the mixture effects of the selected substances.The observed alterations in pigment production affecting carotenoids synthesis in both selected species may be attributed to the differential impacts of these substances on the photosynthetic pathways and metabolic processes in the cyanobacterial and diatom cells. Changes in chlorophyll a fluorescence-specific parameters suggest impairment of the photosynthetic activity, particularly affecting the efficiency of photosystem II.The application of Concentration Addition (CA) and Independent Action (IA) mathematical models, complemented by the evaluation of Model Deviation Ratios (MDR), revealed predominantly antagonistic interactions within the studied mixtures. The findings of this study provide important insights into the effects of mixtures of organic micropollutants and their potential impact on environment including brackish and marine waters.

Catalytic behavior, electronic structure and spectroscopic (FT-IR, Raman, UV–vis) properties for the new ionic liquid imidazolium hydrogen sulfate

Catalytic performance, chemical reactivity, vibrational modes and electronic transitions of the ion pair [H–Im]+[HSO4]– were investigated in the current paper. Hence, a combined experimental (Hammett acidity function, infrared, Raman and ultraviolet-visible spectroscopies) and theoretical (molecular electrostatic potential surface, reduced density gradient, frontier molecular orbital analysis, quantum theory of atoms in molecules, net atomic charges, global and local reactivity descriptors) study was conducted. In terms of the catalytic performance, the acetic acid esterification with butanol was evaluated. Important kinetic (rate constant, activation energy, pre-exponential factor) and thermodynamic (enthalpy, entropy, Gibbs free energy barrier) factors for ester production as a function of the temperature and catalyst loading have been determined. Results revealed intensive electron density distribution in [H–Im]+[HSO4]– due to chemical interactions between the cationic and anionic moieties. These bonds were established as electrostatic in nature. The pronounced charge transfers within [H–Im]+[HSO4]– managed the title compound acidity (H0) and its catalytic behavior towards butyl acetate synthesis. Using the thermodynamic and kinetic measurements, a mechanism for acetic acid esterification with butanol in the presence of imidazolium hydrogen sulfate ionic liquid was offered.

Separation of ethanol/n-hexane azeotrope by imidazolium ionic liquids: Experimental study and mechanism analysis

In the process of producing low-carbon alcohols from coal, azeotropic waste containing ethanol and n-hexane is generated. To prevent environmental risks and resource waste from solvent loss, this study selected green solvent ionic liquids (ILs) for their separation. First, we screened five anions with high selectivity based on the conductor-like screening model for realistic solvents (COSMO-RS), and through various quantum chemical calculations, we found that the anions play a significant role in the separation of the two components, with [HSO4]− showing the best separation performance. Second, we predicted the phase equilibrium data for ILs containing [HSO4] − in the azeotropic system, considering practical factors such as price and viscosity, and selected [EMIM][HSO4], [BMIM][HSO4], and [HMIM][HSO4] for experiments. The results indicated that simpler cation side chains enhance the separation capability of the system. Then, a toxicity analysis of the ILs ensured their biocompatibility and feasibility. Finally, we established the extraction distillation process and visualized the interactions between the ILs and the azeotropic system through molecular dynamics simulations. This work provides theoretical guidance for the separation of alcohols and alkanes in the industry.

Key Roles of Free Cations in Modulating the Reaction Rate in Imidazolium Ionic Liquid-Dimethyl Sulfoxide Mixtures.

Imidazolium ionic liquids (ILs) are widely utilized in various fields due to their distinctive properties. However, their high viscosity limits their application in specific reactions, and mixing ILs with organic components is a way to solve this problem. While previous studies mainly focused on the structural changes of ILs after adding organic molecules, no studies elucidated the influence of their existing species on chemical reactions. In this study, aerobic α-hydroxylation of 2-methylcyclohexanone was chosen as a model reaction, and the reaction rate was found to be adjusted by varying imidazolium concentration in its mixtures with dimethyl sulfoxide. To elucidate the mechanism, the distribution of species in an IL solution and its change with concentration were studied by molecular dynamics simulations, and the results revealed the significant impact of the concentration of free cations on the reaction rate. The interaction between the ionic species and reaction intermediate, as calculated by density functional theory, highlighted the crucial role of free cations in this reaction. This study demonstrates the feasibility of tuning the concentration of free cations by varying the concentration of the IL solution, establishing the relationship between its microstructure and chemical reaction efficiency, thus providing vital information for the design and application of ILs.

In-depth exploration of the interface mechanism of aqueous ammonium-ion batteries with ionic liquids

Aqueous ammonium-ion batteries have emerged as a research focus in recent years because of their distinctive advantages. Nevertheless, issues such as the side reaction of water, electrode element dissolution and others have an impact on their stability. The experimental findings demonstrate that the system incorporating ionic liquids (ILs) exhibits gratifying electrochemical performance. The Molecular Dynamics (MD) simulation approach was employed to investigate the alterations of NH4Cl aqueous batteries prior to and subsequent to the addition of imidazolium ionic liquids (ILs), with a focus on the impact on the anode's interface. It is found that the addition of ILs can reduce the interfacial water’s content at low charge. Interestingly, in the case of high charge, the water content at the interface didn’t decrease; instead, it increased. This phenomenon is associated with the initial increase followed by a decrease in the number of ionic liquid (IL) cations. Three conformations for IL cations were found near the interface, which are “parallel”, “slant” and “vertical”, and the proportion of the three had a certain influence on the content of interfacial water. The "parallel" configuration is more effective in reducing the interfacial water content, establishing it as the dominant conformation. The findings reported above will offer new theoretical support for the design and modification of aqueous ammonium ion electrolytes.

Investigation of the physicochemical and thermodynamic characteristics of imidazole ionic liquids with water and ethanol mixtures

Investigation of the physicochemical and thermodynamic characteristics of imidazole ionic liquids with water and ethanol mixtures

Predicting imidazolium ionic liquid properties with a simple molecular volume-based SAFT-VR Mie approach

Each thermodynamic model requires a distinct set of parameters for each component and these parameters must be transferable beyond their original estimation domain to accurately predict a variety of thermodynamic properties. Previous work introduced and evaluated a novel parametrization method for the solubility of ionic liquids in CO2 or CH4 [Chem. Eng. Sci. 2024, 285, 119610]. This methodology provides a fast and efficient way to evaluate ionic liquids by requiring only their molecular volume. In this study, the approach is extended to include both pure ionic liquids, examining properties such as density, isobaric heat capacity, isobaric expansivity, isothermal compressibility, and speed of sound, as well as their mixtures with ethanol or water, focusing on speed of sound, and excess enthalpy. Ionic liquids are modeled as both non-associating and associating components. Overall, the approach demonstrates good estimates and holds potential for extension to other models and systems.

Customizing Ionic Liquids Functionalized MOFs Composites with Hydrophobic Interface for Electrochemical CO2 Reduction.

The electrochemical carbon dioxide reduction reaction (CO2RR) to generate feedstocks for chemical products (e.g., carbon monoxide, CO) offers a highly attractive method for achieving the closure of the carbon cycle. Ionic liquids (ILs)-functionalized Cu-based catalyst Cu2O-HKUST-1/IL1/PTFE was developed, configuring metal-organic frameworks(MOFs) based materials with high adsorption and multiple active sites. The modified electrocatalysts exhibited high specific surface area, strong CO2 adsorption capacity, abundant active sites, and fast charge transfer rate. The nucleophilic active site of deprotonation at the C2 site in imidazole ILs further improved the selectivity of proton migration and CO product generation, which was verified through DFT calculations for the low Gibbs free energy of the generated intermediate interactions. In addition, the hydrophobic interface constructed by PTFE facilitated the inhibition of the hydrogen evolution reaction (HER) and significantly improved the efficiency of CO2 electroreduction. The Cu2O-HKUST-1/IL1/PTFE catalyst manifested a high C1 Faraday efficiency (FE) up to 96.5% and in particular 92.7% for FECO at -1.7 V vs RHE. The present work provides an efficient strategy for configuring ILs-functionalized MOFs-based materials with good hydrophobic interfaces to enhance the efficiency of CO2 electroreduction to C1 products.

Role of Multiple Intermolecular H-Bonding Interactions in Molecular Cluster of Hydroxyl-Functionalized Imidazolium Ionic Liquid: An Experimental, Topological, and Molecular Dynamics Study

Role of Multiple Intermolecular H-Bonding Interactions in Molecular Cluster of Hydroxyl-Functionalized Imidazolium Ionic Liquid: An Experimental, Topological, and Molecular Dynamics Study

Electrolytes from Alkoxyalkyl-substituted Imidazolium ionic liquids. Synthesis, characterization, properties and cell performance in LiFePO4 half-cells

Electrolytes based on lithium bis(trifluoromethane)sulfonimide (LiTFSI) salt and alkoxyalkyl-substituted imidazolium ionic liquids (ILs) have been studied. We have synthesized three different 1-alkoxyalkyl-3-methylimidazolium TFSI salts with different chain lengths (from 4 to 10 atoms) and with one to three oxygen atoms at position 1- of the imidazole ring. Both the neat ILs as well as the cognate lithium doped electrolytes have been structurally and physicochemically characterized and electrochemically evaluated.Thermal analyses indicate that the glass transition temperature of the electrolytes is displaced to higher temperatures than those of the corresponding neat ILs, being also higher (more positive) upon increasing the number of oxyethylene units. On the other hand, all 1 M LiTFSI doped synthesized electrolytes are thermally stable up to 300 °C.Raman spectroscopy results indicate that the fraction of TFSI anions coordinated to lithium ion decreases on increasing the number of alkoxy units. This finding implies that there is more “free” lithium ion available to link to the ethereal oxygen of the side chain of the imidazolium ring system. This fact influences the ionic conductivity of the neat ILs and their cognate electrolytes.The electrochemical properties —namely high room temperature conductivities as well as wide electrochemical stability windows— indicate that these materials are promising electrolytes for lithium-ion batteries (LIBs). Lithium half-cells using LiFePO4 (LFP) olivine have been assembled in order to assess the electrochemical performance by means of both cyclic voltammetry and galvanostatic charge/discharge tests. Overall, we have found that the electrochemical performance of these cells is better than that reported 1 M LiTFSI [Pyr14][TFSI], a common electrolyte in LIBs. The generated half-cell from the 1-alkoxyalkyl-3-methylimidazolium TFSI salts possess a high capacity up to 145 mAh∙g−1 at a current of 2C.The results reported herein show a striking relationship between structure and properties.

Cationic effect study in acetate-based ionic liquids/ZIF-8 composites for CO2 sorption

Several strategies can be considered for the mitigation of carbon dioxide (CO2) emissions to the atmosphere, and among them is its post-combustion capture/separation from flue gas emitted from coal-fired power plants. In this work, six imidazolium, ammonium- and DABCO-based ionic liquids (ILs) containing the acetate anion were used to impregnate the metal-organic framework (MOF) ZIF-8. The cationic effect was studied to determine how the different cationic families and side alkyl chain size influence the gas sorption performance of the produced IL@MOF composites. The combination of different characterization techniques confirmed IL impregnation, and that the composite materials were microporous and crystalline. Single-component CO2 and nitrogen (N2) sorption-desorption equilibrium measurements were performed at 303 K for ZIF-8 and the IL@ZIF-8 materials. At the low-pressure regime (0–1 bar), synergy was observed for the imidazolium-based composites, especially for the one with the long-side alkyl chain. The ideal CO2/N2 selectivity was calculated for post-combustion composition, and, at 1 bar, [C10MIM][Ac]@ZIF-8 was over four times more selective than ZIF-8, while the selectivity of [C2MIM][Ac]@ZIF-8 at this pressure almost tripled when compared to the MOF. A chemical reaction between CO2 and the imidazolium ILs explained the results.

Vinyl-containing covalent organic frameworks co-polymerized with imidazolium ionic liquids for the efficient cycloaddition of CO2 with epoxides

The chemical fixation of CO2 into high value-added cyclic carbonates over metal- and cocatalyst-free heterogeneous catalyst has attracted considerable attention and is still a challenge. Rationally integrating multifunctional units into porous materials has been regarded as a promising strategy to enhance catalytic efficiency. In this study, the poly (ionic liquid)-hierarchical covalent organic framework (R-PIL-COF, R refers to CH2NH2/CH2OH/COOH/CH3) hybrids were successfully fabricated via in situ copolymerization of vinyl-containing covalent organic framework and hydrogen bond donors (HBDs)-functionalized imidazolium ionic liquids. Among, CH2NH2-PIL-COF hybrid bearing acidic and basic sites possess moderate CO2 adsorption ability and hierarchical pore structure which promoted the activation of CO2 and epichlorohydrin. Furthermore, the influence on the catalytic activity of various HBD groups and grafting amounts of poly (ionic liquid)s were systematically investigated, and CH2NH2-PIL–COF–45 % exhibited an exceptional catalytic performance under mild conditions (100 °C and 1 MPa CO2 pressure). Additionally, CH2NH2-PIL–COF–45 % had broad substrate tolerance and excellent stability. Finally, a synergistic catalytic mechanism was proposed based on the experimental and characterization results. The strategy of co-polymerizing ionic liquids to COF provides a new way to develop efficient COF-based hybrids by the integration of nucleophilic units into the COF skeleton for CO2 fixation under cocatalyst-free and mild conditions.

Influence of imidazole-based ionic liquid surfactants on the wetting effect of long-flame coals

In order to study the wetting effect of C12MImBF4, C12MImBr and C12MImCl on long-flame coal, and their mechanism of action on coal-water bonding, physical experiments, molecular dynamics simulation and DFT theoretical calculation were combined in this work. It is confirmed that the imidazole ionic liquid surfactant optimizes the wetting effect by forming hydrogen bonds, reducing the surface tension of water, and increasing the number of free hydroxyl groups in coal. After the wettability test, the concentration of 4 g/L of the three ionic liquid surfactants had the best wetting effect on long-flame coal, and the contact angle at this concentration was reduced by more than 40 % compared with water within 0.2 s after dripping on the coal. Due to the difference in the anionic head group of the three surfactants, there are differences in the number and strength of hydrogen bonds formed between the three surfactants and water molecules, the results of wettability C12MImBF4 > C12MImCl > C12MImBr were presented. Combined with these characteristics of imidazole ionic liquids on long-flame coal, the reasonable application in the wet dust removal process of actual coal mine production can optimize the efficiency of droplet capture of coal particles, so as to effectively improve the dust removal capacity.

Ruthenium nanoparticle immobilised on ionic liquid polymer as efficient catalyst for the hydrolysis of NaBH4

Development of heterogeneous catalyst is significant key for achieving high performance of NaBH4 hydrolysis to produce hydrogen. The stability of sodium borohydride in the presence of suitable catalyst is the efficient method to generate hydrogen. In this work, styrene-imid PIILP, polymer 1 decorated styrene, imidazolium ionic liquid, and cross-coupling is successfully synthesised by AIBN initiated radical polymerisation, then precipitation with 3,3′,3″phosphinetriyltribenzene sulfonate with ratio (1:0.3) to isolate the first styrene-imid- sulphonated PIILP, polymer 2. RuNP@styrene-imid-sulphonated PIILP, RuNPs catalyst 3 was synthesised by impregnation with RuCl3, then reduction by NaBH4. Moreover, several analytical techniques such as, 31P, 1H, 13C solid-state NMR, CHN, IR, XPS, TEM, TGA-DTA, and SEM were examined to explore the obtained catalyst 3. The hydrogen generation from NaBH4 utilizing catalyst 3 was exhibited the catalytic behaviour studying several parameters such as, temperature, catalytic loading, and NaBH4 concentrations this work was deducted the activation energy (30.32 kJmol-1), and the turnover frequency (TOF) reached up 134.9, 112.77, and 98.38 moleH2.molcat−1.min−1 at 40, 35 and 30 °C. The effectiveness of Ruthenium nanoparticle catalyst 3 for the hydrolysis reaction of NaBH4 was examined in H2O and D2O resulting kinetic isotope effect (KIE) kH/kD = 3. In addition, RuNPs demonstrated a promising efficient for reuse catalyst 3 after five cycles for the catalytic hydrolysis.

Ti[sbnd]F bridged IL-CuCQDs-F/TiO2 inverse opal composite for boosting CO2 visible-photo reduction via slow photon effect

Photocatalytic reduction of CO2 exhibits unsatisfactory photocatalytic performance owing to the inefficient separation of photogenerated electron-hole pairs, low CO2 capture efficiency and limited visible light absorption on most photo-catalysts. Herein, TiF bridged IL-CuCQDs-F/TiO2 inverse opal composite (IO-CFTi) was constructed for boosting CO2 visible-photo reduction via slow photo effect. In this work, ethylenediaminetetraacetic acid (EDTA(Cu)) and imidazole ionic liquid 1-(2-Hydroxyethyl)-3-methylimidazolium tetrafluoroborate ([HOEtMIM][BF4]) were employed to confine grow of IL-CuCQDs-F within TiO2 inverse opal supporter via TiF bonds connection. Unique IL-CuCQDs-F efficiently expended light absorption towards visible region, and the confined growth of IL-CuCQDs-F within the TiO2 inverse opal cavity achieved the photoelectric conversion and efficient CO2 capture. Moreover, their TiF bonding interface of IO-CFTi assisted photogenerated electron transportation from TiO2 to CO2 for its reduction in this system. Consequently, IO-CFTi achieved a substantially increased CO production rate of 78.1 μmol·h−1·g−1 with 98 % selectivity. This improved performance in CO2 photoreduction positions the nanocomposite as a promising material for preservation of the environment and conversion of energy.

Effect of ionic liquid on soft epoxy-amine electroactuators

Energy conversion represents a challenge in various fields of applications such as soft robotics or microfluidics technologies, particularly in terms of electromechanical coupling for actuators. The dielectric elastomers are a variety of electroactive polymers (EAP) which require high electric fields to be used as actuators. It is well-known that the presence of ionic impurities can have an influence of their electro-mechanical response under high electric field (i.e. above 1 MV/m). More precisely, it can be responsible for the bending of the sample under constant electric field. Here, we investigate the impact of a small content, i.e. from 0.1 wt% to 10 wt% of an imidazolium Ionic Liquid (IL) on the electromechanical response of a soft epoxy-amine network. The interest of this study therefore lies in its position at the frontier between dielectric polymers and ionic polymers. Dielectric spectroscopy revealed a significant increase of electric conductivity (≈2 orders of magnitude) when adding only 0.1 wt% of IL and up to 4 orders of magnitude with 10 wt% of IL at T = 20 °C for f = 10 Hz. It also evidenced the presence of the electrode polarization for all the samples doped with IL. The bending test carried out at E = 0.1 MV/m revealed no bending for pure epoxy-amine and a slow kinetics of bending for all the samples doped with IL with displacement evolving throughout the experiment (i.e. over 4 h). As evidenced by dielectric spectroscopy and bending tests, it is clear that the presence of a small quantity of ionic moieties (whether doping agent or impurity) can strongly modify the electromechanical behavior of elastomer commonly described as dielectric.

Imidazole ionic liquid effects on coal swelling behavior and pyrolysis characteristics: Experiment and molecular simulation

In view of low-rank coal conventional swelling solvent large pollution and the clean efficient utilization of coal, the effects of imidazole ionic liquid (IL) pretreatment with different anion groups as green solvent on coal thermal expansion and pyrolysis performance were investigated. IL interacts with coal molecules, destroying the hydrogen bonds, resulting coal expansion. Different anion groups have different modification effects, [Bmim]Cl has the best swelling effect, which is 17.37 % higher than raw coal, and the best modification time is 24 h. In addition, IL modification has a catalytic effect on coal pyrolysis, which can significantly reduce the maximum weight loss temperature and increase tar content. Coal solvent pretreatment provides a good theoretical basis for application of swelling and pyrolysis. The reduction of thermochemical reaction temperature not only reduces the content of heavy groups in pyrolysis products, but also provides new ideas for carbon emission reduction.

The design of molecularly dispersed tungstovanadate catalyst via ionic liquid linkers for oxidative desulfurization

The sulfur removal process in diesel is one of the key technologies to produce clean energy using polyoxometalate (POM)-based catalyst with excellent catalytic active sites. Herein, a molecularly dispersed POM supported catalyst CNT@(C4mim)4VW12O40 (CNT@C4VW12) was designed by introducing imidazole ionic liquids (IL) [C4mim]Br as counterionic linkers for oxidation desulfurization (ODS). For the model oil, 100 % desulfurization rate and product selectivity can be achieved within 30 min, and it can be recycled for 5 times without obviously decrease. Moreover, CNT@C4VW12 also displayed excellent performance in real hydrotreated diesel with a removal rate of 97.4 %. Overall, a stable and molecularly dispersed catalyst was constructed by the cooperative effect of π-π stacking, hydrogen bonding and electrostatic force interaction among the CNT, [C4mim]+ and [VW12O40]4−, which would provide new inspirations for design of heterogeneous catalyst towards excellent ODS process.

Zwitterionic and vinyl-N-imidazolium ionic liquids

In this paper, we present employing our own and literature data the results of investigation of the thermal behavior and ion transport properties of vinyl and alkyl imidazolium zwitterions containing an alkane sulfonic acid group and salts on their basis. For comparison, we present the results of investigation the respective vinyl and alkyl imidazolium ILs without these functional groups. The phase behavior of zwitterionic and vinyl imidazolium ionic liquids is studied by differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA).

Preparation of imidazolium ionic liquid functionalized paper membrane for selective extraction of caffeic acid and its structural and functional analogues from Taraxaci Herba.

In the search for pharmaceutically active compounds from natural products, it is crucial and challenging to develop separation or purification methods that target not only structurally similar compounds but also those with specific pharmaceutical functions. The adsorption-based method is widely employed in this field and holds potential for this application, given the diverse range of functional monomers that can be chosen based on structural or functional selectivity. In this work, an imidazolium ionic liquid (IL) modified paper membrane was synthesized via microwave reaction. Caffeic acid (CA), with potential interactions with imidazolium IL and a representative component of phenolic acids in Taraxaci Herba, was chosen as a target compound. After optimization of synthesis and extraction parameters, the resulting extraction membrane could be used to quantitatively analyze CA at ng/ml level, and to extract CA's analogues from the sample matrix. Cheminformatics confirmed the presence of structural and functional similarity among these extracted compounds. This study offers a novel approach to preparing a readily synthesized extraction membrane capable of isolating compounds with structural and functional analogies, as well as developing a membrane solid-phase extraction-based analytical method for natural products.