Structure Of Ionic Liquids Research Articles

Ionic Liquids as Promisingly Multi-Functional Participants for Electrocatalyst of Water Splitting: A Review.

Ionic liquids (ILs), as one of the most concerned functional materials in recent decades, have opened up active perspectives for electrocatalysis. In catalyst preparation, ILs act as characteristic active components besides media and templates. Compared with catalysts obtained using ordinary reagents, IL-derived catalysts have a special structure and catalytic performance due to the influence of IL's special physicochemical properties and structures. This review mainly describes the use of ILs as modifiers and reaction reagents to prepare electrocatalysts for water splitting. The designability of ILs provides opportunities for the ingenious composition of cations or anions. ILs containing heteroatoms (N, O, S, P, etc.) and transition metal anion (FeCl4-, NiCl3-, etc.) can be used to directly prepare metal phosphides, sulfides, carbides and nitrides, and so forth. The special physicochemical properties and supramolecular structures of ILs can provide growth conditions for catalysts that are different from the normal media environment, inducing special structure and high performance. ILs as heteroatom sources are safe, green and easy to operate compared with traditional heteroatom sources. The strategy for using ILs as reagents is expected to realize 100% atomic transformation of reactants, in line with the concept of green chemistry. This review reflects the discovered work with the best findings from the literature. It will offer readers a deeper understanding on the development of IL-derived electrocatalysts and inspire them to ingeniously design high-performance electrocatalysts for water splitting.

Infrared reflection absorption spectroscopy of the adsorbed structures of a protic ionic liquid on the low-index planes of Pt

Modification with a protonic ionic liquid containing [7-methyl-1,5,7-triazabicyclo[4.4.0]dec-5-ene (MTBD)][bis(pentafluoroethanesulfonyl)imide (beti)] enhanced the activities of the cathodic reactions of fuel cells (oxygen reduction reactions (ORR)) on Pt(111) and Pt(110), whereas it deactivated Pt(100). To elucidate the reaction mechanism, the ORR inhibiting species (PtOH) and the adsorption geometries of [MTBD][beti] on the low-index planes of Pt were studied using infrared reflection absorption spectroscopy (IRRAS). After modification with [MTBD][beti], the intensity of the bands representing PtOH decreased in the spectra of all the low-index planes. The adsorbed MTBD was tilted toward Pt(111) and vertically adsorbed onto Pt(110). On Pt(100), MTBD was adsorbed with its molecular plane parallel to the surface. Bands representing adsorbed beti were observed in the spectra of all surfaces. The increased ORR activities of the Pt(111) and Pt(110) surfaces were attributed to the decrease in PtOH formation after [MTBD][beti] modification and the low steric hindrance of the vertically adsorbed MTBD. Meanwhile, the deactivation of Pt(100) can be attributed to the increased steric hindrance of the parallel adsorption geometry of MTBD.

Morpholine-Based Novel Ionic Liquid for Synthesis and Characterization of Triazolidinethiones and Their Biological Properties

Keeping the green chemistry approach in mind we have synthesized a novel morpholine-based ionic liquid [NBMMorph]<sup>+</sup>Br<sup>-</sup>. The structure of Ionic liquid was confirmed by spectral techniques <em>viz</em>. IR, <sup>1</sup>H NMR, and<sup> 13</sup>C NMR, analysis. The synthesized novel IL [NBMMorph]<sup>+</sup>Br<sup>-</sup> was utilized to prepare 1,2,4-triazolidine-3-thiones of biological significance. The [NBMMorph]<sup>+</sup>Br<sup>- </sup>IL shows excellent catalytic activity, and a simple filtration technique can separate the thiazolidinedione products. The structure of the synthesized compounds were confirmed using IR and NMR techniques. All the synthesized compounds were screened for their antimicrobial activity. All compounds shows outstanding biological activity.

Thermodynamic model for CO2 absorption in imidazolium-based ionic liquids using cubic plus association equation of state

In order to achieve efficient capture of carbon dioxide (CO2) by ionic liquids (ILs), IL with good performance of high CO2 absorption capacity and low energy consumption need to be explored. Density, heat capacity, CO2 solubility and absorption enthalpy are key properties for the performance evaluation of IL solvents. In this work, the cubic plus association equation of state (CPA EoS) was applied for the integrated modelling of above properties in CO2 physical and chemical absorption by 22 imidazolium-based ILs. The results show that the density, heat capacity of pure ILs and CO2 solubility in a broad range of temperature (281–403 K) and pressure (0.1–23 MPa) were accurately calculated with deviations less than 1.27%, 0.54% and 3.73%, respectively. CO2 chemisorption was satisfactorily described by CPA EoS with an error of 0.12% considering interactions for the reactive sites between CO2 and amino groups in IL. Furthermore, the prediction capabilities of CPA EoS were verified with results showing good quantitative agreement with density and solubility data in literature. The effects of structures of ILs studied in this work on the CO2 solubility and absorption enthalpy were analyzed. [NH2emim][BF4], [Omim][Tf2N] and [Emim][eFAP] were found to have better performance of CO2 absorption. This model provides a feasible approach to determine synthetically the key properties of CO2-IL systems for the selection of proper ILs, design and simulation of the CO2 capture process.

New Mn(III)/Fe(III) complexes with thiohydantoin-supported imidazolium ionic liquids for breast cancer therapy

This study offers, for the first time, the design and synthesis of hybrids integrating imidazolium ionic liquids (IMILs) and thiohydantoins (THs) motifs and their Mn/Fe(III) complexes for cancer therapeutic applications. The molecular structures of thiohydantoin-supported imidazolium ionic liquids (THIMILs) (4a-c) and their complexes were proposed based on microanalytical and spectroscopic investigations. On the other hand, the UV–Vis spectroscopic and magnetic measurements, as well as comparisons with previously reported comparable complexes, led to the postulation of square pyramidal and octahedral geometries for Mn(III)THIMIL and Fe(III)THIMIL complexes, respectively. According to the MTT cytotoxicity assay results, the new hybrids inhibited MCF-7 cell proliferation more effectively than HepG2 and selectively as well. The anti-breast cancer performance varies depending on the hybrid structure, dose, and treatment duration. Among the compounds tested, Fe(III)THIMIL analog (6b) was the most active and selective anti-MCF-7 agent (IC50 1.98±0.56 μM, SI 34.92). It was found that 6b has the capacity to trigger G2/M cell cycle arrest and apoptosis in MCF-7 cells, presumably through a p50 route. Meanwhile, the molecular docking of 6b with Bcl-2 and p50 proteins showed great promise in the field of cancer treatment by modulating the levels of expression in these proteins.

Lubricity of chelated orthoborate-phosphonium ionic liquids on tetrahedral amorphous carbon and steel surfaces

In boundary lubrication, formation of tribofilms and subsequent friction and wear properties are strongly influenced by lubricant affinity to the lubricating surfaces. Ionic liquids (ILs), which are composed of ions, are expected to provide enhanced surface affinity compared to molecular liquids. This is also of interest for non-ferrous surfaces such as diamond-like carbon (DLC) coatings. DLC technology is widely utilised for sliding components, but DLC performance with conventional lubricants does not always fulfil the requirements. In this study, we compare lubricating performance of two non–halogenated ILs with a common cation, trihexyl(tetradecyl)phosphonium, but different anions, bis(oxalato)borate and bis(mandelato)borate, in the steel/steel and steel/DLC contacts. The tribofilms formed and their lubrication mechanism are investigated using a wide range of surface analysis techniques: Atomic Force Microscopy (AFM), nano-indentation, SEM-EDX and X-ray Photoelectron Spectroscopy (XPS). It is demonstrated that both ILs exhibited better lubricating performance than PAO oils of similar viscosity. It is also shown that the lubricating performance is controlled by the chemical stability of ILs, surface hardness and topography. The phosphonium bis(oxalato)borate IL exhibited excellent lubricity but its performance was adversely affected by the rough and very hard DLC surface that disrupted a delicate balance between the rates of tribofilm formation and removal. A higher chemical stability of the phosphonium bis(mandelato)borate IL facilitated formation of a non-sacrificial ionic tribofilm that reduced friction to a lower extent than the phosphonium bis(oxalato)borate IL but without accelerated tribochemical wear. The results demonstrate the potential for controlling lubrication properties by tuning functional groups of anion structure and subsequent chemical reactivity of ILs with lubricated surfaces.

Linking Molecular Structure and Lubrication Mechanisms in Tetraalkylammonium Orthoborate Ionic Liquids

While ionic liquids (ILs) have gained wide interest as potential alternative lubricants able to meet the requirements of next-generation tribological systems owing to their unique physico-chemical properties and promising lubricating behavior, our understanding of the mechanisms by which ILs reduce friction and/or wear is still elusive. Here, we combine macroscale tribological experiments with surface-analytical measurements to shed light on the lubrication mechanisms of a class of halogen-free ILs, namely tetraalkylammonium orthoborate ILs, at steel/steel sliding contacts. The tribological results indicate an improvement of the friction-reducing properties of these ILs as the length of the alkyl chains attached to ammonium cations increases. X-ray photoelectron spectroscopy analyses provide further evidence for the dependence of the lubrication mechanism of tetraalkylammonium orthoborate ILs on the IL structure. In the case of tetraalkylammonium orthoborate ILs with asymmetric ammonium cations containing a long alkyl chain, no sacrificial tribofilms were formed on steel surfaces, thus suggesting that the friction-reducing ability of these ILs originates from their propensity to undergo a pressure-induced morphological change at the sliding interface that leads to the generation of a lubricious, solid-like layered structure. Conversely, the higher friction response observed in tribological tests performed with tetraalkylammonium orthoborate ILs containing more symmetric ammonium cations and short alkyl chains is proposed to be due to the inability of this IL to create a transient interfacial layer owing to the reduced van der Waals interactions between the cationic alkyl chains. The resulting hard/hard contact between the sliding surfaces is proposed to lead to the cleavage of boron-oxygen bonds in the presence of water to form species that then adsorb onto the steel surface, including trivalent borate esters and oxalic acid from the decomposition of orthoborate anions, as well as tertiary amines from the degradation of alkylammonium cations induced by hydroxides released during the orthoborate decomposition reaction. The results of this work not only establish links between the molecular structure of a class of halogen-free ILs, their lubricating performance, and lubrication mechanism, but also provide evidence for the existence of multiple mechanisms underpinning the promising lubricating properties of ILs in general.

Prediction of the Solubility of Acid Gas Hydrogen Sulfide in Green Solvent Ionic Liquids via Quantitative Structure–Property Relationship Models Based on the Molecular Structure

Ionic liquids (ILs) can be used as capturing acidic gases that damage the environment. By establishing a quantitative structure–property relationship (QSPR) model of the IL structure, temperature, pressure, and H2S solubility, it can be used to screen ILs with excellent properties. In this study, molecular descriptors (MD), molecular identifiers (MI), and combinations of MD and MI (MD_MI) are used to represent the structure of ILs, combining pressure and temperature as the input of the model; the QSPR model is built by coupling the two models of the deep neural network (DNN) and random forest (RF). We find that the model constructed by using MI to represent ILs and DNN has the best performance. The Shapley additive explanation (SHAP) method is used to analyze features to obtain the most valuable molecular structure information for prediction. The results show that the contribution degree and direction of different MD and MI in the prediction of H2S solubility are different and correctly identify the impact of environmental factors (temperature and pressure). Finally, the electrostatic potential (ESP) between H2S and ILs was calculated to study the influence of different carbon chain lengths on the solubility of H2S.

Evaluation of Solubility, Physicochemical Properties, and Cytotoxicity of Naproxen-Based Ionic Liquids.

To solve the problems associated with poorly water-soluble nonsteroidal anti-inflammatory drugs (NSAIDs), naproxen-based ionic liquids (ILs) containing naproxen as an active pharmaceutical ingredient (API) anion were prepared with benzalkonium (tetradecyldimethylbenzyl ammonium), choline, and 1-octyl-3-methylimidazole as the cation. The structures and thermal properties were analyzed. Through the conductivity method, the solubility at 25 and 37 °C and the critical micelle concentration (CMC) at 25 °C were determined in water and ethanol. The octanol-water partition coefficients (K ow) at 25 °C were measured with the shake-flask method. The cytotoxicity was evaluated with the MTT method. The results showed that the conversion of naproxen into the API-ILs increased the API's solubility in water by more than 850 times compared with the original API, and the thermostability was satisfactory with a lower glass transition temperature (t g). Moreover, the variation trends of solubility, hydrophilicity, and K ow were consistent with the different structures of naproxen-based ILs, except for benzalkonium naproxen. The CMC (10-5-10-6 M) in water and ethanol demonstrated that the naproxen-based ILs were surface activite ILs. The IC50 values exhibited the low cytotoxicity of the naproxen-based ILs, which was better than 100 μM. The results provide essential information and a research basis for future topical and transdermal administration and oral administration of naproxen-based ILs.

Quantification of the impact of water on the wetting behavior of hydrophilic ionic liquid: a molecular dynamics study

ABSTRACT We have used molecular dynamics (MD) simulations to investigate the effect of water on the wetting behaviour and the interfacial structure of ionic liquid (IL) 1-ethyl-3-methylimidazolium tetrafluoroborate [EMIM][BF4] droplets on graphite surfaces which, is a prerequisite for the IL-based applications where the solid-fluid interface is involved. A slight decrement in the value of the contact angle has been found while adding water up to 17 wt% (∼0.68) afterward, the contact angle increases. The non-monotonic behaviour in the contact angle of IL-water droplet with the addition of water molecules was examined through several key parameters, such as solid-fluid interaction energy, the density profile of each species, cluster formation, and the number of formed hydrogen bonds (HBs) for the different weight percentages of water molecules. The results indicate that the hydrogen bond network and the cluster formation among the water molecules play a vital role during the transition from IL rich medium to water rich medium of the droplet.

Structure of ionic liquids and concentrated electrolytes from a mesoscopic theory

Recently, underscreening in concentrated electrolytes was discovered in experiments and confirmed in simulations and theory. It was found that the correlation length of the charge-charge correlations, λs, satisfies the scaling relation λs/λD∼(a/λD)n, where λD is the Debye screening length and a is the ionic diameter. However, different values of n were found in different studies. In this work we solve this puzzle within the mesocopic theory that yielded n = 3 in agreement with experiments, but only very high densities of ions were considered [A. Ciach and O. Patsahan, J.Phys.: Condens. Matter33, 37LT01 (2021)]. Here we apply the theory to a broader range of density of ions and find that different values of n in the above scaling can yield a fair approximation for λs/λD for different ranges of a/λD. The experimentally found scaling holds for 2<a/λD<4, and we find n = 3 for the same range of the reduced Debye length. For smaller a/λD, we find n = 2 obtained earlier in several simulation and theoretical studies, and still closer to the Kirkwood line we obtain n = 1.5 that was also predicted in different works. It follows from our theory that n = 3 (i.e. λs is proportional to the density of ions) when the variance of the local charge density is large, and λs is proportional to this variance times the Bjerrum length. Detailed derivation of the theory is presented.

Synthesis of Zinc Sulfide Nanoparticles Using Pyridinium Ionic Liquids

Zinc sulfide nanoparticles (quantum dots) were synthesized from aqueous solutions of sodium sulfide and zinc sulfate using pyridinium ionic liquids. The average sizes of zinc sulfide nanoparticles were determined by UV spectroscopy, X-ray diffraction, probe and scanning electron microscopy. The influence of the structure and concentration of pyridinium ionic liquids with the tetrafluoroborate anion of the same name on the size of zinc sulfide nanoparticles has been studied. The effect of the precursor concentration on the size of the nanoparticles formed in the ash was established.

Correction to “Electrical Double Layer Structure in Ionic Liquids and Its Importance for Supercapacitor, Battery, Sensing, and Lubrication Applications”

Correction to “Electrical Double Layer Structure in Ionic Liquids and Its Importance for Supercapacitor, Battery, Sensing, and Lubrication Applications”

The effect of alkyl chain length on imidazole chloroaluminate ionic liquid/Pt(1 1 1) interface and aluminum deposition: A DFT-D3 study

The structure, active sites, and adsorption mechanism of imidazole-based ionic liquids ([CnMIM]Al2Cl7) (n = 1, 2, 4, or 6) on the Pt(111) surface and their effects on aluminum electrodeposition were evaluated by first-principles approaches. The active sites of imidazolium ILs were on the cationic imidazole ring. The adsorption order was [HMIM]Al2Cl7 >[BMIM]Al2Cl7 >[EMIM]Al2Cl7 > [C1MIM]Al2Cl7. The electrostatic interaction, electrostatic induction, and the interfacial dipole effect made the ionic liquids with longer alkyl chain increase the coverage of cations on the Pt(111) surface as well as the number of charge transfers from ionic liquids to the Pt(111) surface, and decrease the distance between chlorine atoms and the Pt(111) surface. This is beneficial to suppress the dendrite formation during the electrochemical process and deposit aluminum in smaller sizes. These results will provide a basis for the selection of efficient ionic liquids of aluminum electrodeposition.

Effect of Surface Characteristics of Graphene Aerogels and Hydrophilicity of Ionic Liquids on the CO2/CH4 Separation Performance of Ionic Liquid/Reduced Graphene Aerogel Composites

Two ionic liquids (ILs) having the same cation with different anions offering opposite hydrophilic/hydrophobic characters, 1-n-butyl-1-methylpyrrolidinium dicyanamide ([BMPyr][DCA]) and 1-n-butyl-1-methylpyrrolidinium hexafluorophosphate ([BMPyr][PF6]), were impregnated onto two different reduced graphene aerogels (rGAs) prepared by the thermal treatment of GAs at 300 and 500 °C to investigate the consequences of the changes in the hydrophilic character of ILs and the reduction temperature of the GAs on the corresponding gas sorption and separation performance of the IL/rGAs. The structural analyses of nanoporous rGAs and IL/rGAs pointed to a change in the quantity of oxygenated functional groups upon thermal treatment and a change in the direct interactions between IL molecules and the host rGA surface upon IL deposition. Single-component CO2 and CH4 sorption measurements were performed for each rGA and IL/rGA composite, and both ideal and mixture CO2/CH4 selectivities were calculated. The samples prepared by reducing the GA at 300 and 500 °C yielded ideal CO2/CH4 selectivities of 3.6 and 18 at 1 mbar and 25 °C, respectively. Among IL/rGA composites, the one prepared at 300 °C displayed a remarkable CO2/CH4 separation performance when combined with the hydrophobic [BMPyr][PF6], offering an ideal selectivity of 450.9 at 1 mbar and 25 °C, whereas the composite prepared with rGA500 yielded a substantially high CO2/CH4 selectivity of 173.5 after the incorporation of the hydrophilic [BMPyr][DCA] at 1 mbar and 25 °C. The ideal CO2/CH4 selectivities of [BMPyr][PF6]/rGA300 and [BMPyr][DCA]/rGA500 surpassed most of the previously reported selectivities of carbon-based materials in the literature. These results demonstrate the broad potential of IL/rGAs in sorption-based gas separations owing to the highly tunable nature of both the structure of IL and the surface characteristics of rGA.

BMIm][BARF] imidazolium salt solutions in alkyl carbonate solvents: Structure and interactions

Solutions of weakly coordinating ionic liquids (ILs) in alkyl carbonates are gaining growing attention, as the latter are “green” solvents with high solvation power, but the phase behavior and structure of ILs in organic polar solvents are still poorly understood. Here, we study the interactions and nanoscale structure of 1‑butyl‑3-methylimidazolium tetrakis[3,5-bis(trifluoromethyl)phenyl]borate, [BMIm][BARF], in three symmetrical alkyl carbonate solvents with increasing alkyl chain-length. Electrical conductivity and nuclear magnetic resonance measurements showed that [BMIm][BARF] was mostly undissociated in these solvents, especially at lower IL concentration. Small angle X-ray scattering patterns evidenced the presence of rod-like nanostructures in the IL/solvent mixtures. At higher IL concentration, [BMIm][BARF] is increasingly more dissociated in solvents with lower dielectric constant, as confirmed by analysis of the solvents’ carbonyl stretching band via Fourier transform infrared spectroscopy. This trend is opposite to that exhibited by BMIm ILs with less bulky counterions. The bulky BARF− is weakly coordinating and has no ability to give strong H-bonding, thus short-range anisotropic van der Waals forces are likely key in the interaction of the ion pairs. The slower self-diffusion of the ions in alkyl carbonates with lower dielectric constants might partially hinder close contact needed for self-assembly into local nano-sized structures. Overall, our results shed light on interactions and self-organization in imidazolium salt-alkyl carbonate mixtures, with potential impact in applicative fields spanning from batteries, catalysis and extraction, up to bio-applications (antimicrobial and bioengineering).

Design of sustainable ionic liquids based on l-phenylalanine and l-alanine dipeptides: Synthesis, toxicity and biodegradation studies

A series of dipeptide ionic liquids (ILs) with l-phenylalanine and l-alanine fragments in structure were synthesized and their possible degradation pathways were analyzed. Based on this analysis, potential transformation products (PTPs) were proposed and synthesized. All of these compounds (25 in total) went through microbial toxicity screening and aerobic biodegradation testing. Obtained results demonstrated that by investigating ILs and PTPs with a dipeptide fragment (in tandem with single amino acid analogues), the design of ILs with high biodegradation values in closed bottle test can be accomplished. One finding was that within the scope of the compounds studied, l-phenylalanine containing compounds were more biodegradable than l-alanine derivatives. In addition to the choice of amino acid residue, its position in the dipeptide IL structure also had a significant effect on biodegradability. PyCH2CO-Phe-Ala-OEt IL, where l-phenylalanine was in close proximity to the positively charged pyridinium sub-unit, gave higher biodegradation percentages compared to PyCH2CO-Ala-Phe-OEt IL, where alanine was closer to pyridinium than the phenylalanine residue. Analysis of PTPs data showed that the presence of an alanine residue resulted in undesirable (less green) PTPs more often compared to PTPs containing phenylalanine, especially when alanine was in close proximity to the pyridinium headgroup. Based on both toxicity and biodegradation testing results preferable and less preferable subunits can be chosen for the design of new sustainable chemicals based on amino acids. Results from this study demonstrate a potential of designing new sustainable chemicals using amino acid moieties as part of their structure.

Investigation of dihydroxyl ionic liquids as high-performance shale inhibitors and their inhibition mechanism

Ionic liquids (ILs) are incredibly efficient additives to solve wellbore instability resulting from shale hydration. The influence of the molecular structure of ILs on their inhibition performance has been investigated intensively, and hydroxyl is regarded as the significant group to improve their inhibition performances. In this study, three novel dihydroxyl ionic liquids (DHILs) including [C4DIPA]Br, [C8DIPA]Br, and [C12DIPA]Br were successfully synthesized. Then their thixotropy and inhibition properties were evaluated via three-interval thixotropy tests (3ITTs), hot-rolling recovery tests, immersion tests, and linear swelling tests. [C12DIPA]Br exhibited the optimal inhibition ability at a low concentration (0.5 wt%) and was more effective than the conventional inhibitor KCl (2 wt%). Various techniques were used to analyze the inhibition mechanism of DHILs including contact angle measurements, zeta potential, X-ray diffraction, and Flourier transform infrared spectroscopy. The results demonstrated that the synergistic effects of hydrogen bonding, electrostatic interaction, and hydrophobic shield should be responsible for the excellent inhibition performance and great thermal stability of [C12DIPA]Br. Finally, the proposed mechanism was supported by the control experiments using other three ILs inhibitors and molecular dynamics simulation. Our work provided unique perspectives on developing rationally designed and efficient ILs inhibitors.

Electrochemical Properties and Local Structure of the TEMPO/TEMPO+ Redox Pair in Ionic Liquids.

Redox-active organic species play an important role in catalysis, energy storage, and biotechnology. One of the representatives is the 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO) radical, used as a mediator in organic synthesis and considered a safe alternative to heavy metals. In order to develop a TEMPO-based system with well-controlled electrochemical and catalytic properties, a reaction medium should be carefully chosen. Being highly conductive, stable, and low flammability fluids, ionic liquids (ILs) seem to be promising solvents with easily adjustable physical and solvation properties. In this work, we give an insight into the local structure of ILs around TEMPO and its oxidized form, TEMPO+, underlining striking differences in the solvation of these two species. The analysis is coupled with a study of thermodynamics and kinetics of oxidation in the frame of Marcus theory. Our systematic investigation includes imidazolium, pyrrolydinium, and phosphonium families combined with anions of different size, polarity, and flexibility, opting to provide a clear and comprehensive picture of the impact of the nature of IL ions on the behavior of radical/cation redox pairs. The obtained results will help to explain experimentally observed effects and to rationalize the design of TEMPO/IL systems.

Experiment and Molecular Mechanism of Two Chlorinated Volatile Organic Compounds in Ionic Liquids

The structure–property relationship between ionic liquids (ILs) and two chlorinated volatile organic compounds (CVOCs), dichloromethane (DCM) and 1,2-dichloroethane (DCE), was systematically investigated. The suitable IL was screened using the COSMO-RS model, and 1-ethyl-3-methylimidazolium acetate [EMIM][Ac] was considered the optimal absorbent to capture the two CVOCs. The vapor–liquid equilibrium experiment demonstrates that the addition of the IL significantly reduces the vapor pressures of the IL + DCM (or DCE) systems. The structure of ILs on the absorption performance was investigated by absorption capacity experiments. Then, the absorption mechanism was investigated through QC calculations and wavefunction analysis. The consistency between the experiments and the molecular mechanism reveals that the formation of the hydrogen bond between the IL and CVOC enhances the absorption process.