Series Of New Ionic Liquids Research Articles

Alkylammonium bis(trifluoromethylsulfonyl)imide as a dopant in the hole-transporting layer for efficient and stable perovskite solar cells

We develop a new series of ionic liquids with dual functionality as a dopant for hole transport materials and a passivator for perovskite surfaces, which enables the production of large-area solar modules with efficiencies approaching 20%.

Tetraalkylammonium-based dicationic ionic liquids (ILs) for CO2 capture

This investigation includes the synthesis and characterization of a new series of ionic liquids (ILs) based on the tetraalkylammonium dication for the absorption of CO2, a step towards the development of more efficient and sustainable technologies.

Dimethylthioformamide-derived ionic liquids: Synthesis, characterization and application as supercapacitor electrolyte

Amide-derived ionic liquids (ILs), especially dimethylformamide (DMF)-derived ILs, have been recently attractive as potential electrolyte with high conductivity and decent electrochemical window, but very poor thermal stability. Here dimethylthioformamide (DMTF) that contains a sulfur atom instead of the oxygen atom in DMF was used to prepare a series of new ILs. DMTF-based ILs exhibit significantly improved thermal stability, with thermal decomposition temperature up to 351 °C, which is about 150 °C higher than that of their DMF counterparts. All of the DMTF ILs are liquid at ambient temperature and show moderate to good physicochemical properties, including density, refractive index, surface tension, viscosity and conductivity. The dynamic viscosity and conductivity obey both the Arrhenius and VFT temperature dependence. Although the electrochemical properties, i.e. conductivity and electrochemical window, of DMTF ILs are inferior to DMF ILs, [C1-DMTF]NTf2 with relatively high conductivity and wide electrochemical window gives decent performance as supercapacitor electrolyte, with specific capacitance of 90 F·g−1 at a stable operating voltage of 2.0 V.

Synthesis of Chiral Ionic Liquids from Natural Monosaccharides

AbstractThree series of new ionic liquids (ILs), namely imidazolium‐, pyrazolium‐, and bis‐benzimidazolium‐containing ILs, were prepared from low‐cost, unprotected carbohydrates. Information on anion‐cation interactions and solvation shell were obtained via diffusion NMR and heteronuclear Overhauser correlation maps (HOESY), respectively.

New series of ionic liquids based on benzalkonium chloride derivatives: Synthesis, characterizations, and applications

New series of ionic liquids based on benzalkonium chloride derivatives are presented in this work. The new ionic liquids are recognized by elemental analysis, Fourier transform infrared (FTIR), and hydrogen nuclear magnetic resonance (1H NMR). They have been considered as promising anti-corrosion and anti-microbial additives in the petroleum industry. In this paper, the anti-corrosion and anti-microbial activities of four synthesized benzalkonium chloride derivatives (BCIL) are measured for carbon steel structure immersed in the formation water and contaminated solution by sulfate-reducing bacteria (SRB). The anti-corrosion properties of BCIL are evaluated using chemical and electrochemical methods. The anti-microbial activities of BCIL were tested against SRB. Collectively, the results confirmed that the new ionic liquids (BCIL) play as anti-corrosion and anti-microbial additives. These new additives led to protect the carbon steel structure from corrosion caused by formation water and from bio-corrosion caused by SRB.

Thermophysical properties of 4-dimethylaminopyridine based ionic liquids

In this study, a molecular simulation (Gaussian03) was used to analyze the chemical structure of 4-dimethylaminopyridine (DMAP) to investigate its use for the synthesis of ionic liquids (ILs). Based on DMAP, a series of new ILs was prepared and characterized by fourier transform infrared spectroscopy (FT-IR), 1H nuclear magnetic resonance (1H-NMR), thermogravimetric analysis (TGA), and differential scanning calorimeter (DSC). The density data of the studied ILs were measured from 328.15 K to 358.15 K, p = 0.101 MPa. It is shown that density decreases with an increase in the temperature and the alkyl chain length of cations. And density is also affected by the anion type. Furthermore, the volume of ions, NBO charges, and the interactions of anions and cations were calculated by Gaussian03 to explain the obtained density results. The second-order polynomial equation was adopted to correlate the relationship of density and temperature. Then, an isobaric thermal expansion coefficient, molecular volume, and lattice potential energy were obtained from the density data. Viscosity was determined from 323.15 K to 368.15 K, p = 0.101 MPa. It is determined that the viscosity of ILs decreases with an increase in the temperature but increases with an increase in the alkyl chain length of cations. The temperature dependence of viscosity was described by the Vogel-Fulcher-Tamman (VFT) model, and the activation energy of viscous flow (Eη) was obtained. Furthermore, the decomposition temperature (Td), glass transition temperature (Tg), and melting temperature (Tm) of ILs were obtained from the results of TGA and DSC.

Toward Designing “Sweet” Ionic Liquids Containing a Natural Terpene Moiety as Effective Wood Preservatives

This study is focused on the utilization of naturally occurring terpene alcohol in the synthesis of ionic liquids (ILs) and their application potential in wood protection. A new series of ILs containing a natural, renewable source of (−)-menthol in the cation and a saccharinate derivative as the anion were obtained with a high yield under mild process conditions. The potential applications of synthesized compounds that belong to surface-active compounds were assessed for wood preservation, and they showed positive results. Laboratory tests of their activity against fungi and saccharinate-based chiral ionic liquid (CIL) bonding with Scots pine (Pinus sylvestris L.) wood are described. The biological results for salts with alkyl substituents ranging from pentyl to octyl chains are very promising, and their activity is similar to, and even higher than, that of the commonly used material benzalkonium chloride. The fungicidal values of saccharinate-based CILs against Coniophora puteana ranged from 2.75 to 4.4 ...

Synthesis, Properties, and Structures of Low‐Melting Tetraisocyanatocobaltate(II)‐Based Ionic Liquids

A series of new ionic liquids of the formula Ax[CoII(NCO)4] with the [CoII(NCO)4]2– anion and nitrogen‐based organic cations (A) were synthesized. The single‐crystal structures of all of the compounds were determined by X‐ray diffraction, and the presence of discrete ions was revealed for all cases. At room temperature, these compounds exhibit paramagnetic behavior owing to the presence of high‐spin tetrahedrally coordinated CoII ions. The melting points or glass‐transition temperatures are in the range for ionic liquids for some of the compounds with singly charged cations and above 100 °C for all compounds with doubly charged cations and the bis(triphenylphosphine)iminium ([PPN]+) salt. Each compound was characterized by elemental analysis as well as NMR, IR, and UV/Vis spectroscopy. Measurements of the density, dynamic viscosity, conductivity, and surface tension of the low‐melting substance [EMIm]2[Co(NCO)4] ([EMIm]+ = 1‐ethyl‐3‐methylimidazolium) show that they differ slightly to the corresponding values for the isothiocyanato complexes but are generally comparable.

Synthesis and characterization of novel hexafluorophosphate salts with tropine-type cations

In this study, a series of new ionic liquids (ILs) with tropine as cationic nucleus and hexafluorophosphate as anion were synthesized. As two types of functional groups, aliphatic chains and benzyl with different substituents have been linked on the tropine nucleus in order to modulate the physicochemical properties of the ILs. The whole family of ILs was comprehensively identified by FT-IR, NMR and MS. Furthermore, the thermal properties of these ILs were evaluated by different scanning calorimetry (DSC) together with their melting points and enthalpy of fusion. Then the polarities of these tropine-type ILs were investigated and discussed. Resultantly, it was proved that their polarity was comparable with that of short-chain alcohols. Moreover, the Hammett function values of these involved ILs were determined to describe their Brønsted acidities. Finally, molar conductivities (Λ) of the tropine-type ILs in dilute solutions at 298.15K were determined. The data were correlated with the Arrhenius–Ostwald model to obtain limiting molar conductivities (Λ∞) and association constants (KA). The influences of the branch chain of ILs on the ion transfer and association were also discussed. It was found that the size of cation was the main factor influencing the ion transfer. And the weak ion association of tropine-type ILs in water was proved by KA, which was less than 7L·mol−1.

Tribological and corrosive properties of ionic liquids containing triazole functional groups

Purpose – The aim of this paper was to inhibit the serious corrosion of conventional ionic liquids, a series of new ionic liquids (ILs) containing the triazole functionality, as the anti-corrosion groups were synthesized in this work. Design/methodology/approach – It is well known that nitrogen and sulfur containing organic compounds have been traditionally used as corrosion inhibitors. Among them, triazole derivatives are most often used as corrosion inhibitors. To alleviate the corrosion of the ILs and further improve the anti-wear property, the authors prepared a series of imidazolium ILs modified with the triazole functionality in the present study. Findings – The corrosion behavior of the ILs was evaluated with the iron disk corrosion test and their tribological properties were investigated on an Optimol SRV IV oscillating friction and wear tester at elevated temperatures. The results showed that the ILs with the triazole functionality could effectively reduce the corrosion and exhibit a smaller friction coefficient and wear volume than the unmodified counterpart. The ILs containing the triazole functionality can be used as the single component anti-corrosion base oils even at elevated temperatures. Originality/value – The results showed that the ILs with the triazole functionality could effectively reduce the corrosion and exhibit a smaller friction coefficient and wear volume than the unmodified counterpart. The ILs containing the triazole functionality can be used as the single component anti-corrosion base oils even at elevated temperatures.

Synthesis and Characterization ofO-Alkylated Amidium Ionic Liquids

In the present study, a new series of ionic liquids (ILs) derived from low-cost amides and lactams (cyclic amides), such as N,N-dimethylformamide (DMF), were synthesized and characterized. Unlike other nucleophiles like amines, the alkylation reaction of the amides with alkyl triflates to form cationic species takes place at the carbonyl oxygen atom, instead of the nitrogen atom. For these O-alkylated amidium ILs, the basic physicochemical properties, such as melting point, glass transition temperature, plastic crystal phase transition, thermal stability, density, surface tension, viscosity, ionic conductivity and electrochemical window, were investigated and studied. Generally, these ILs are distinguished by low viscosity and high conductivity, in particular the DMF-derived ILs with viscosity as low as 21.6 cP and conductivity up to 15.45 mS cm–1 at 25 °C. This result should be attributed to the cationic DMF structures: planar geometry, low symmetry, C2-proton and ether moiety, resulting in much lower viscosity and higher conductivity than the best-known imidazolium ILs. Meanwhile, these amidium ILs also possess wide electrochemical windows (∼4.5 V) comparable to imidazolium ILs, implying their potential in electrochemical applications. Furthermore, several of the amidium ILs can form plastic crystal with a maximum enthalpy gain of −35.7 J g–1 at the temperature range of −10–90 °C.

Ionic Liquids Based on the 7‐Azabicyclo[2.2.1]heptane Skeleton: Synthesis and Properties

AbstractBased on a previously developed method for the synthesis of epibatidine analogues, a series of new ionic liquids, based on the 7‐azabicyclo[2.2.1]heptane skeleton, have been synthesized. The chemical and physical properties of the ionic liquids with bis(trifluoromethylsulfonyl)imide (Tf2N) and dicyanamide [N(CN)2] anions were investigated and they were found to exhibit very good electrochemical and thermal stabilities.

Cycle Performance of Lithium-Ion Batteries Containing Ionic Liquids with Improved Reduction Stability

The high-temperature cycling performance of lithium-ion batteries containing a new series of ionic liquids based on an aliphatic quaternary ammonium cation and a bis(fluorosulfonyl)amide anion were investigated, by conducting charge-discharge cycling tests of graphite / LiFePO4 cells. The new series of ionic liquids were 1,3-dimethyl-1-propylpiperidinium bis(fluorosulfonyl)amide (3mPP13-FSA) and 7-methyl-5-azoniaspiro[4,5]decane bis(fluorosulfonyl)amide (7mAS45-FSA), which were obtained by introducing methyl groups to known compounds. The relationship between a change in electronic structure and reduction stability was researched. Introducing methyl group improved reduction stability as electron-donating ability. Further, melting points were lowered owing to the asymmetric structures of the cations. The electrochemical properties of these ionic liquids were evaluated by linear sweep voltammetry. The cycle performance of graphite/LiFePO4 cells containing these ionic liquids for the electrolytes was improved compared with that of cells containing organic electrolytes based on LiPF6/ECDEC, and the capacity retention ratios were more than 50% at the 500th cycle at 60°C.

POSS fillers for modulating the thermal properties of ionic liquids

We report a polyhedral oligomeric silsesquioxane (POSS)-based filler for improving the thermal properties of ionic liquids (ILs). We prepared homogeneous mixtures containing the octa-substituted carboxy-POSS as a filler via a solution process. Initially, it was found that the melting temperatures of the ionic pairs were lowered by adding the POSS filler. Based on this effect, some of ionic salts were transformed into ILs by adding the POSS filler. Reinforcement of thermal stability was also observed from the salts which have an intrinsically low decomposition temperature. According to the thermodynamic parameters in melting, the introduction of the POSS filler significantly reduces both the fusion enthalpy and entropy. Furthermore, from experiments on the substituent effect on POSS, it was found that only octa-carboxy POSS had an effect on the modulation of the thermal properties of ion salts. Considering these results, we summarized that the highly symmetrical rigid structure of the silica cage could be responsible for the improvement of the thermal properties of the ion salt matrices via the strong interaction between the carboxyl groups and the ion salt matrices. Our concept is feasible not only for the conversion of conventional ionic salts into ILs, but also for the development of new series of ILs.

Synthesis and properties of trialkyl(2,3-dihydroxypropyl)phosphonium salts, a new class of hydrophilic and hydrophobic glyceryl-functionalized ILs

A series of new ionic liquids (ILs) based on trialkylglycerylphosphonium cations have been prepared starting from 3-chloropropane-1,2-diol or (2,2-dimethyl-1,3-dioxolan-4-yl)methanol, two compounds readily obtainable from glycerol (a widely available and cheap waste product). All the new phosphonium salts were characterized by NMR, IR and DSC, and their efficacy as polar additives in a typical base-promoted Baylis–Hillman reaction was also evaluated.

Evaluation of Hydroxyalkyl-Functionalized Imidazolium-based Ionic Liquids as Solvents for the Extraction of Metal Ions

As part of a broader effort to evaluate the suitability of a variety of ionic liquids (ILs) as solvents for the extraction of actinides and fission products, a series of new ILs containing a (1-hydroxyalkyl)-functionalized imidazolium cation have been prepared and characterized. Although certain of their physicochemical properties (e.g., density, liquidus range) remain largely unaffected vs their N,N′-dialkylimidazolium analogs by hydroxyl-functionalization, other characteristics (e.g., hydrophilicity) are measurably changed. In addition, this functionalization has been found to alter the “balance of pathways” among the various routes by which a metal ion may partition between aqueous nitric acid solutions and ionic liquids containing a neutral extractant.

Effect of sulfonate-based anions on the physicochemical properties of 1-alkyl-3-propanenitrile imidazolium ionic liquids

In this paper, the physicochemical properties of a new series of ionic liquids (ILs) based on nitrile-functionalised imidazolium cations ([C2CN Cnim]+) with sulfonate-based anions were studied. The ILs were prepared by reacting imidazole with acrylonitrile, followed by butyl- and decyl bromide. The anions of the resulting bromide salts exchanged by metathesis to dioctylsulfosuccinate (DOSS), dodecylsulfate (DDS), benzenesulfonate (BS) and trifluoromethanesulfonate (TFMS). The densities of these ILs are lower compared to the those of other reported nitrile-functionalised ILs, while on the other hand, the viscosities of the ILs are higher due to the effects of the large anions and the long alkyl chain of the cations.

Dialkoxy functionalized quaternary ammonium ionic liquids as potential electrolytes and cellulose solvents

A series of new ionic liquids, based on dialkoxy-functionalized quaternary ammonium cations {side chains: 1 = CH3, 1O1 = CH3OCH2, 1O2 = CH3OC2H4, 2O2 = C2H5OC2H4; cations: [N11,1O1,1O2], [N11,1O1,2O2], [N11,1O2,1O2], [N11,1O2,2O2] and [N11,2O2,2O2]}, with BF4−, (CF3SO2)2N− (NTf2) and CH3CO2− (OAc) as counteranions, have been prepared and characterized. Their basic properties, such as spectroscopic characteristics, melting point, glass transition temperature, thermal stability, electrochemical window, density, refractive index, viscosity and conductivity, were measured and comparatively studied. The incorporation of two flexible alkoxy chains makes the quaternary ammonium salts highly qualified to be low-viscous and high-conductive room temperature ILs, and even some of them have significantly better fluidity than the popular imidazolium ILs with a similar molecular weight, e.g.[N11,1O1,2O2]BF4 (151 cP and 2.11 mS cm−1, Mw: 249) vs.[HMIm]BF4 (220 cP and 1.2 mS cm−1, Mw: 256) at 25 °C. The electrochemical windows of these ILs were evaluated up to 5.5 V. In addition, the dialkoxy OAc ILs were found to have excellent solvent power for cellulose under mild conditions, e.g. a solution of 18 wt% microcrystalline cellulose in [N11,2O2,2O2]OAc at 80 °C. By precipitation with water, the dissolved cellulose (I crystal structure) was regenerated as nanosized cellulose II particles with increased surface area and decreased crystallinity, determined by FE-SEM and XRD.

A NEW CLASS OF IONIC SOLVENTS, ELECTROLYTES AND ENGINEERING FLUIDS BASED ON 1,3-ALKYLMETHYL-1,2,3-BENZOTRIAZOLIUM SALTS

A new series of ionic liquids based on 1,3-alkylmethyl-1,2,3-benzotriazolium cation has been prepared. The spectroscopic, physical and electrochemical characteristics of this family of salts have been investigated with respect to potential usage as ionic solvents, electrolytes and engineering fluids. Incorporation of diverse anions including weak coordinating anion and pseudohalide with this benzotriazolium cation produces ionic liquids with advantageously low melting points and good thermal stability. Thermal analyses of these very stable salts included the determination of melting points (-65 to 164 oC) and decomposition temperatures (up to 291 oC). The electrochemical windows of representative benzotriazolium species has been investigated by cyclic voltammetry and determined to be ~ 3 V. The X-ray single crystal and spectroscopic studies revealed that weak hydrogen-bonding interactions between the benzotriazolium ring protons and the anions are present both in the solid state as well as in solution. Keywords: ionic liquids, X-ray single crystal, thermal analysis, electrochemical analysis, benzotriazolium salt

Phosphonium ionic liquids based on bulky phosphines: synthesis, structure and properties

A series of new ionic liquids based on sterically hindered decyl(tri-tert-butyl)phosphonium (DTBP) or decyl(tricyclohexyl)phosphonium (DCHP) cations were prepared using quaternisation of tri-tert-butyl- or tricyclohexylphosphine with decylbromide and subsequent bromide exchange with the weakly-coordinating anions BF(4)(-), PF(6)(-), SO(3)CF(3)(-), N(SO(2)CF(3))(2)(-). The salts obtained melt below 100 degrees C and possess a broad electrochemical window. Density functional theory combined with X-ray crystallography, IR and Raman spectroscopy has been used to analyze the molecular and supramolecular structures of the compounds obtained and their possible influence on their physical properties.