Anion Of Ionic Liquid Research Articles

One-pot sustainable synthesis of tetrabutylammonium bis(trifluoromethanesulfonyl)imide ionic liquid

Tetrabutylammonium bis(trifluoromethanesulfonyl)imide (TBA TFSI) and tetrafluororate-based anion ionic liquids (ILs) were obtained simultaneously by using a fast, versatile, cheap, low cost, and one-pot process. The process relies on dissolving tetrabutylammonium tetrafluoroborate salt, an organic-based bis(trifluoromethanesulfonyl) imide, ILs, such as 1-ethyl-3-methylimidazolium, N-trimethyl-N-butylammonium, 1-butyl-1-methylpyrrolidinium, 1-methyl-1-propylpiperidinium derivatives in dimethylformamide. A further extraction process using water and ether allows the selective recovery of the TBA TFSI in the organic phase, and the organic-based tetrafluoroborate IL in the aqueous phase. All the ionic liquids synthetized were characterized using Infrared Spectroscopy and Nuclear Magnetic Resonance, and compared with commercially available samples.

Catalytic hydrogenation of levulinic acid in ionic liquid mixtures using hydrogen gas in high-pressure CO2

Hydrogenation of levulinic acid (LA) to γ-valerolactone (GVL) in ionic liquid (IL) mixtures with hydrogen gas in high-pressure CO2 was studied to demonstrate tuning of product selectivity. Ethyl- or butyl- imidazolium-based cation with Cl, acetate [OAc], diethylphosphate, bis(trifluoro-methanesulfonyl)imide or tetrafluoroborate anion IL mixtures were used as the reaction phase with Pd/C, Pd/Al2O3 or Ru/Al2O3 commercial catalysts. Experiments were performed with batch reactors using (1 to 5) MPa partial pressure H2 at nominal pressures of 8 MPa at 110 °C. GVL selectivities as high as 88% at 50% conversion were obtained in [EMIM]Cl-[EMIM][OAc] using 3 MPa partial pressure H2 in presence of CO2 at 4 h reaction time. Specific interactions of LA with Cl anion IL and CO2 with [OAc] anion IL are key to the reaction mechanism. Reaction systems containing Cl anion - [OAc] anion IL mixtures with H2 gas and CO2 have wide application to hydrogenation of biomass-related compounds.

Adjusting the chromatographic properties of poly(ionic liquid)‐modified stationary phases by substitution on the imidazolium cation

Poly(ionic liquid)-modified stationary phases can have multiple interactions with solutes. However, in most stationary phases, separation selectivity is adjusted by changing the poly(ionic liquid) anions. In this work, two poly(ionic liquid)-modified silica stationary phases were prepared by introducing the cyano or tetrazolyl group on the pendant imidazolium cation on the polymer chains. Various analytes were selected to investigate their mechanism of retention in the stationary phases using different mobile phases. Two poly(ionic liquid)-modified stationary phases can provide various interactions toward solutes. Compared to the cyano-functionalized poly(ionic liquid) stationary phase, the tetrazolyl-functionalized poly(ionic liquid) stationary phase provides additional cation-exchange and π-π interactions, resulting in different separation selectivity toward analytes. Finally, applicability of the developed stationary phases was demonstrated by the efficient separation of nonsteroidal anti-inflammatory drugs.

Solvent extraction of intra-lanthanides using a mixture of TBP and TODGA in ionic liquid

The recovery and separation of trivalent lanthanides into individual elements is difficult owing to their similar chemical behaviours. In this study, the solvent extraction of trivalent lanthanide ions from nitric acid solutions in an organic phase comprising a mixture of two electrically neutral extractants, viz. tri(n-butyl)phosphate (TBP) and N,N,N′,N′-tetra(n-octyl)diglycolamide (TODGA), is investigated. The hydrophobic room-temperature ionic liquid (IL), 1-methyl-3-butyl-imidazolium bis(trifluoromethanesulfonyl)imide, is employed as a more environmentally benign diluent compared to the conventional molecular solvents. The results reveal that the addition of TBP as a co-extractant with TODGA not only significantly enhances the metal ion extraction but also affords high intra-lanthanide ion selectivity. This is attributed to the formation of complex lanthanide species with both TBP and TODGA. In addition, when IL is used as a diluent, the cationic exchange between metal–organic ligand species and IL cations, as well as neutral complex extraction result in a more efficient extraction. Moreover, the hydrophobic anionic IL entities can also be involved in the extraction mechanism, affording lipophilic metal–organic ligand complexes. The synergistic solvent combination of TODGA, TBP, and IL can afford an excellent separation of the lanthanide(III) ions.

Comprehensive analysis of chloroaluminate and composite ionic liquids using direct analysis in real time mass spectrometry

<p indent=0mm>A composite chloroaluminate ionic liquid (IL) modified with copper(I) chloride has attracted considerable attention due to its high catalytic activity and selectivity for isobutane alkylation, where the bimetallic anions of Cu(I)-Al(III) have been proposed to play important roles. Characterization of chloroaluminate and composite ionic liquids (CIL) is crucial for a better understanding of alkylation mechanism and catalysts design. In this work, a plasma-based ion source, direct analysis in real time (DART), was introduced to achieve soft but effective ionization of chloroaluminate IL and CIL with minimized hydrolysis, fragmentation and salt effects. Combined with the isotope patterns strategy and high-energy collision dissociation (HCD) technology, this developed high resolution mass spectrometry (HRMS) method, DART-Orbitrap-HRMS, was not only able to identify the accurate chemical composition of chloroaluminate IL and CIL, but also capable of structure analysis. Based on the comparison of chloroaluminate IL and CIL, it showed that similar acidic anions in both ILs were [AlCl₄]⁻, [Al₂Cl₇]⁻ and [Al₃Cl₁₀]⁻. The remarkable difference was the verification of Cu(I)-Al(III) bimetallic anions as [CuAlCl₅]⁻ and [CuAl₂Cl₈]⁻ merely in CIL, which were proposed to count for the high catalytic activity. Moreover, Cu(I) cation ion that might be related to the alkylation selectivity was characterized as [(Et₃NH)₂CuCl₂]⁺ in CIL. Structure analysis of the two bimetallic anions were then achieved by HCD technology. All the results have provided substantial support for the structure-activity study of CIL, setting the stage for in-depth research on IL-catalyzed isobutane alkylation.

Assessing the ecotoxicity of ionic liquids on Vibrio fischeri using electrostatic potential descriptors

Ionic liquids (ILs) have attracted increasing attention both in the scientific community and the industry in the past two decades. Their risk of being inevitable released to ecosystem lights up the urgent research on their toxicity to the environment. To reduce the time and capital consumption on testing tremendous ILs ecotoxicity experimentally, it is essential to construct predictive models for estimating their toxicity. The objective of this study is to provide a new approach for evaluating the ecotoxicity of ILs. A comprehensive ecotoxicity dataset for Vibrio fischeri involving 142 ILs, was collected and investigated. The electrostatic potential surface areas (SEP) of separate cations and anions of ILs were firstly applied to develop predictive models for ecotoxicity on Vibrio fischeri. In addition, an intelligent algorithm named extreme learning machine (ELM) was employed to establish the predictive model. The squared correlation coefficients (R2), the average absolute error (AAE%) and the root-mean-square error (RMSE) of the developed model are 0.9272, 0.2101 and 0.3262 for the entire set, respectively. The proposed approach based on the high R2 and low deviation has remarkable potential for predicting ILs ecotoxicity on Vibrio fischeri.

Synthesis of silver nanoparticles in green binary solvent for degradation of 2,4-D herbicide: Optimization and kinetic studies

In this study, well-dispersed and diminutive Ag nanoparticles have been successfully synthesized in binary solvent of Orthosiphon stamineus (OS) leaves extract and ionic liquids (ILs) via electrochemical method. ILs namely [BMIM Tf2N], [BMIM BF4] and [EMIM EtSO4] were used as solvent in the synthesis process to produce AgTf2N, AgBF4, and AgEtSO4. The characterization of Ag nanoparticles revealed that the particle size of the silver nanoparticles can be easily altered depending on the size of IL alkyl chain and anion, to produce ultrafine particles ranging from 8 to 25nm. Meanwhile, the photocatalytic activity of AgTf2N nanoparticles effectively degraded the highest amount of 2,4-dichlorophenoxyacetic acid (2,4-D) herbicide at 65.61%. The optimized model gave high removal percentage of 2,4-D at 97.80% (pH=3.24; catalyst dosage=0.009g/L; 2,4-D concentration=8.15mgL−1) with validation experiments of 1.28% error. Investigation of kinetic reaction showed the applicability of pseudo-first order kinetic to the process of 2,4-D degradation (R2>0.98) which positively predicted the constant elimination amount of 2,4-D throughout the photocatalytic process. Overall, the studies construed the crucial role of binary solvent in synthesizing and controlling the size of Ag nanoparticles for pollutant degradation.

Ultrafast vibrational dynamics of a trigonal planar anionic probe in ionic liquids (ILs): A two-dimensional infrared (2DIR) spectroscopic investigation.

A major impediment limiting the widespread application of ionic liquids (ILs) is their high shear viscosity. Incorporation of a tricyanomethanide (TCM-) anion in ILs leads to low shear viscosity and improvement of several characteristics suitable for large scale applications. However, properties including interactions of TCM- with the local environment and dynamics of TCM- have not been thoroughly investigated. Herein, we have studied the ultrafast dynamics of TCM- in several imidazolium ILs using linear IR and two-dimensional infrared spectroscopy techniques. The spectral diffusion dynamics of the CN stretching modes of TCM- in all ILs exhibit a nonexponential behavior with a short time component of ∼2 ps and a long time component spanning ∼9 ps to 14 ps. The TCM- vibrational probe reports a significantly faster relaxation of ILs compared to those observed previously using linear vibrational probes, such as thiocyanate and selenocyanate. Our results indicate a rapid relaxation of the local ion-cage structure embedding the vibrational probe in the ILs. The faster relaxation suggests that the lifetime of the local ion-cage structure decreases in the presence of TCM- in the ILs. Linear IR spectroscopic results show that the hydrogen-bonding interaction between TCM- and imidazolium cations in ILs is much weaker. Shorter ion-cage lifetimes together with weaker hydrogen-bonding interactions account for the low shear viscosity of TCM- based ILs compared to commonly used ILs. In addition, this study demonstrates that TCM- can be used as a potential vibrational reporter to study the structure and dynamics of ILs and other molecular systems.

Inhibition of hyperthermostable xylanases by superbase ionic liquids

The use of enzymes in aqueous solutions of ionic liquids (ILs) could be useful for the enzymatic treatment of lignocellulose. Hydrophilic ILs that dissolve lignocellulose are harmful to enzymes. The toleration limits and enzyme-friendly superbase IL combinations were investigated for the hyperthermophilic Thermopolyspora flexuosa GH10 xylanase (endo-1,4-β-xylanase EC 3.2.1.8) TfXYN10A and Dictyoglomus thermophilum GH11 xylanase DtXYN11B. TfXYN10A was more tolerant than DtXYN11B to acetate or propionate-based ILs. However, when the anion of the ILs was bigger (guaiacolate), GH11 xylanase showed higher tolerance to ILs. 1-Ethyl-3-methylimidazolium acetate ([EMIM]OAc), followed by 1,1,3,3-tetramethylguanidine acetate ([TMGH]OAc), were the most enzyme-friendly ILs for TfXYN10A and [TMGH]+-based ILs were tolerated best by DtXYN11B. Double-ring cations and a large size anion were associated with the strongest enzyme inhibition. Competitive inhibition appears to be a general factor in the reduction of enzyme activity. However, with guaiacolate ILs, the denaturation of proteins may also contribute to the reduction in enzyme activity. Molecular docking with IL cations and anions indicated that the binding mode and shape of the active site affect competitive inhibition, and the co-binding of cations and anions to separate active site positions caused the strongest enzyme inhibition.

Electromechanically active polymer actuators based on biofriendly choline ionic liquids

Smart and soft electroactive polymer actuators have many beneficial properties, making them attractive for biomimetic and biomedical applications. However, the selection of components to fabricate biofriendly composites has been limited. Although biofriendly options for electrodes and membranes are available, the conventional ionic liquids (ILs) often used as the electrolytes in the actuators have been considered toxic in varying degrees. Here we present a smart electroactive composite with carefully designed and selected components that have shown low toxicity and a biofriendly nature. In the present study, polypyrrole-PVdF trilayer actuators using six different choline ILs were prepared and characterized. Choline ILs have shown promise in applications where low environmental and biological impact is critical. Despite this, the anions in ILs have a strong impact on toxicity. To evaluate how the anions effect the bioactivity of the ILs used to prepare the actuators, the ILs were tested on different microbial cultures (Escherichia coli, Staphylococcus aureus, Shewanella oneidensis MR-1) and HeLa cells. All of the selected choline ILs showed minimal toxic effects even at high concentrations. Electro-chemo-mechanical characterization of the actuators indicated that polypyrrole-PVdF actuators with choline ILs are viable candidates for soft robotic applications. From the tested ILs, choline acetate showed the highest strain difference and outperformed the reference system containing an imidazolium-based IL.

Asymmetric effects of anions in magnetic ionic liquids

Phase behaviors and magnetic properties of magnetic ionic liquids (mILs) were investigated at low temperature. The mILs were [C4mim][FeCl4], [C4mim][FeCl3Br], [C4mim][FeCl2Br2], [C4mim][FeClBr3], and [C4mim] [FeBr4], where [C4mim]+ is 1-butyl-3-methylimidazolium. The formation of symmetric and asymmetric anions was identified using Raman spectroscopy. In addition, [C4mim][FeCl4], [C4mim][FeCl3Br], and [C4mim][FeCl2Br2] indicated a paramagnetic behavior of magnetic susceptibility, which obeyed the Curie-Weiss law. In [FeClBr3]−-, and [FeBr4]−-based mILs, crystallization was induced at a low temperature upon cooling. Moreover, nonparamagnetic magnetic susceptibility was observed in [C4mim][FeClBr3], and [C4mim][FeBr4].

The highly stable air-operating ionic polymer metal composite actuator with consecutive channels and its potential application in soft gripper

In this study, a highly stable air-operating ionic polymer–metal composite (IPMC) actuator with consecutive channels suitable for transportation of the cations and anions of ionic liquids was prepared by introducing and removing copper foam. The electromechanical properties of this novel porous IPMC were investigated. Scanning electron microscopy observation showed that channels and pores ranging in size from ∼100 nm to ∼50 μm were distributed in the Nafion membrane. The porous IPMC was doped with 1-ethyl-3-methylimidazolium thiocyanate ionic liquid. A larger capacitance (285.00 mF cm−2) was obtained, which can be attributed to the electric double layer generated at the interface between the ionic polymer membrane and platinum electrode under the input voltage. The fast ion migration channels, high conductivity, and large capacitance enabled high strain of 0.051%–0.666%, a relatively large blocking force of 17.63 mN, and excellent actuation durability for more than 180 000 cycles to be achieved. Furthermore, a soft gripper consisting of a bio-inspired micropillar dry adhesive glued on one surface of the porous IPMC assembled with a mobile mechanical arm was fabricated, and the soft gripper successfully grabbed objects with various features.

Harnessing Ionic Interactions and Hydrogen Bonding for Nucleophilic Fluorination.

We review recent works for nucleophilic fluorination of organic compounds in which the Coulombic interactions between ionic species and/or hydrogen bonding affect the outcome of the reaction. SN2 fluorination of aliphatic compounds promoted by ionic liquids is first discussed, focusing on the mechanistic features for reaction using alkali metal fluorides. The influence of the interplay of ionic liquid cation, anion, nucleophile and counter-cation is treated in detail. The role of ionic liquid as bifunctional (both electrophilic and nucleophilic) activator is envisaged. We also review the SNAr fluorination of diaryliodonium salts from the same perspective. Nucleophilic fluorination of guanidine-containing of diaryliodonium salts, which are capable of forming hydrogen bonds with the nucleophile, is exemplified as an excellent case where ionic interactions and hydrogen bonding significantly affect the efficiency of reaction. The origin of experimental observation for the strong dependence of fluorination yields on the positions of -Boc protection is understood in terms of the location of the nucleophile with respect to the reaction center, being either close to far from it. Recent advances in the synthesis of [18F]F-dopa are also cited in relation to SNAr fluorination of diaryliodonium salts. Discussions are made with a focus on tailor-making promoters and solvent engineering based on ionic interactions and hydrogen bonding.

The Effect of Concentration of Lithium Salt on the Structural and Transport Properties of Ionic Liquid-Based Electrolytes.

Ionic liquids (ILs) are used as electrolytes in high-performance lithium-ion batteries, which can effectively improve battery safety and energy storage capacity. All atom molecular dynamics simulation and experiment were combined to investigate the effect of the concentration of lithium salt on the performance of electrolytes of four IL solvents ([Cnmim][TFSI] and [Cnmim][FSI], n = 2, 4). The IL electrolytes exhibit higher density and viscosity; meanwhile, larger lithium ion transfer numbers as the concentration of LiTFSI increases. Furthermore, in order to explore the effect of the concentration of lithium salt on the ionic associations of Li+ and anion of IL, the microstructures of the lithium salt in various IL electrolytes at different concentrations were investigated. The structural analysis indicated that strong bidentate and monodentate coordination was found between Li+ and anion of all IL electrolytes. Both cis and trans isomerism of [FSI]− were observed in [FSI]−-type IL electrolyte systems. Furthermore, the existence of the ion cluster [Li[anion]x](x−1)− in IL electrolytes and the cluster became more closed and compact as the concentration of LiTFSI increases.

Acute toxicity, oxidative stress and DNA damage of three task-specific ionic liquids ([C2NH2MIm]BF4, [MOEMIm]BF4, and [HOEMIm]BF4) to zebrafish (Danio rerio)

The addition of different functional groups to ionic liquid anions or cations to synthesize task-specific ionic liquids (TSILs) according to specific needs has become a research hotspot. However, there are few studies on the toxicity of TSILs. We selected zebrafish (Danio rerio) to assess the toxicity of three TSILs 1-aminoethyl-3-methylimidazolium tetrafluoroborate ([C2NH2MIm]BF4), 1-methoxyethyl-3-methylimidazolium tetrafluoroborate ([MOEMIm]BF4) and 1-hydroxyethyl-3-methylimidazolium tetrafluoroborate ([HOEMIm]BF4). The 96 h median lethal concentration (96 h LC50) of the three TSILs [C2NH2MIm]BF4, [MOEMIm]BF4 and [HOEMIm]BF4 on zebrafish determined by an acute toxicity test were 143.8 mg/L, 2492.5 mg/L and 3086.7 mg/L, respectively. In the oxidative damage and DNA damage research experiments, zebrafish were exposed to [C2NH2MIm]BF4 (0, 5, 10, 20 and 40 mg/L), [MOEMIm]BF4 and [HOEMIm]BF4 (0, 1, 10, 50 and 100 mg/L) for 28 days, and levels of reactive oxygen species (ROS), superoxide dismutase (SOD), catalase (CAT), glutathione S-transferase (GST), malondialdehyde (MDA) and olive tail moment (OTM) in zebrafish liver were tested on days 7, 14, 21 and 28 after the exposure test. During the experiment, increased contents of ROS and MDA were detected; enzymatic activities especially SOD were inhibited; and DNA damage occurred in zebrafish. The toxicity of the three TSILs was compared by the integrated biomarker response (IBR). The toxicity order of three TSILs was: [MOEMIm]BF4 > [HOEMIm]BF4 > [C2NH2MIm]BF4. In addition, this study can provide a toxicological basis for application research and the evaluation of functionalized ionic liquids with low toxicity in the future.

Recent progress in self-healable ion gels

ABSTRACT Ion gels, soft materials that contain ionic liquids (ILs), are promising gel electrolytes for use in electrochemical devices. Due to the recent surge in demand for flexible and wearable devices, highly durable ion gels have attracted significant amounts of attention. In this review, we address recent advances in the development of ion gels that can heal themselves when mechanically damaged. Light- and thermally induced healing of ion gels are discussed as stimuli-responsive healing strategies, after which self-healable ion gels based on supramolecular and dynamic covalent chemistry are addressed. Tough, highly stretchable, and self-healable ion gels have recently been fabricated through the judicious design of polymer nanostructures in ILs in which polymer chains and IL cations and anions interact. The applications of self-healable ion gels to electrochemical devices are also briefly discussed.

Effect of temperature, nature of anion and alkyl chain length on the volumetric and acoustic properties of ionic liquid [C4C1im][MeSO4] with alkyl nitriles

Densities (ρ) and speeds of sound (u) of 1-butyl-3-methylimidazolium methyl sulphate, [C4C1im][MeSO4] with acetonitrile (ACN), propionitrile (PCN) and n-butyronitrile (n-BCN) in the complete composition range at temperatures between 298.15 K and 313.15 K with 5 K intervals and atmospheric pressure is reported. Solute-solvent interactions have been evaluated in the mixtures of [C4C1im][MeSO4] with alkyl nitriles by calculating excess volumes (VE) and excess isentropic compressibilities (κsE). The VE and κsE values as a function of mole fraction are correlated using a Redlich-Kister type expression. The excess functions (VE and κsE) are found to be negative over the complete range of mole fraction for the investigated binary solutions. The studied excess properties are found to increase with the increase in the alkyl chain length of alkyl nitriles. The excess thermodynamic properties of the mixed solvents are discussed in relation to intermolecular interactions and structural effects existing between the component molecules. In addition, the effect of the nature of anion of ionic liquid and temperature on the excess thermodynamic properties has been investigated.

Probing the ionic transport dynamics in ionic liquid incorporated CuBTC-Metal-Organic Framework based PVdF-HFP nanocomposite membranes

CuBTC-Metal-Organic Framework (MOF) has been prepared by solvothermal synthesis method and ionic liquid (IL) 1-butyl-3 methylimidazolium tetrafluoroborate (BMIMBF4) has been incorporated at different wt% into the CuBTC-MOF. The composite nanofiller has been dispersed in poly (vinylidene fluoride-co-hexafluoropropylene) (PVdF-HFP) polymer electrolyte system. Shifting of FTIR vibrational modes of carboxylate group is due to metal-ligand bond elongation upon interaction of ions of IL with CuBTC-MOF. The binding energy of Cu spin-orbit peak increases with incorporation of IL as obtained from XPS spectra suggesting motion of BF4− anions of IL towards the Cu metal nodes of MOF. Periodic oscillation and coordination structure of Cu K-edge are observed in k-space and R-space scanning EXAFS data. Non-Debye dielectric relaxation dynamics is observed from dielectric permittivity and modulus spectra with ionic conductivity of 8.7 × 10−3 Scm−1at 50 wt% of IL incorporation in the composite polymer electrolyte at 380 K. The electrochemical stability profile increases with increasing IL concentration and attains 6.1 V at 50 wt% of IL.

Conformational design concepts for anions in ionic liquids.

The identification of specific design concepts for the in silico design of ionic liquids (ILs) has been accomplished using theoretical methods. Molecular building blocks, such as interchangeable functional groups, are used to design a priori new ILs which have subsequently been experimentally investigated. The conformational design concepts are developed by separately and systematically changing the central (imide), bridging (sulfonyl) and end (trifluoromethyl) group of the bis(trifluoromethanesulfonyl)imide [N(Tf)2]− anion and examining the resultant potential energy surfaces. It is shown that these design concepts can be used to tune separately the minimum energy geometry, transition state barrier height and relative stability of different conformers. The insights obtained have been used to design two novel anions for ILs, trifluoroacetyl(methylsulfonyl)imide [N(Ms)(TFA)]− and acetyl(trifluoromethanesulfonyl)imide [N(Tf)(Ac)]−. The computationally predicted structures show excellent agreement with experimental structures obtained from X-ray crystallography. [C4C1im][N(Tf)(Ac)] and [C4C1im][N(Ms)(TFA)] ILs have been synthesised and ion diffusion coefficients examined using pulsed field gradient stimulated echo NMR spectroscopy. Significantly increased diffusion was observed for the more flexible [N(Tf)(Ac)]− compared with the more rigid [N(Ms)(TFA)]− analogue. Furthermore, a pronounced impact on the fluidity was observed. The viscosity of the IL with the rigid anion was found to be twice as high as the viscosity of the IL with the flexible anion. The design concepts presented in this work will enable researchers in academia and industry to tailor anions to provide ILs with specific desired properties.

Expanding the design space of gel materials through ionic liquid mediated mechanical and structural tuneability

The mechanical strength of ionogels correlates with polymer structure, which is dependent on the basicity of the ionic liquid anion.