Pyrrolidinium Cations Research Articles

Microscopic study of binary mixtures between pyrrolidinium bis(triflorosulfonyl)imide and dimethyl sulfoxide/acetonitrile

Molecular interactions of a representative pyrrolidinium-based ionic liquid 1-butyl-1-methyl-pyrrolidinium bis(triflorosulfonyl)- imide ([BMPyrr][TFSI]) with dimethyl sulfoxide (DMSO) and acetonitrile (AN) have been analyzed in this work. Attenuated total reflection Fourier transform infrared spectroscopy (ATR-FTIR) and density functional theory (DFT) calculations are used in the investigation, while excess infrared spectra and two-dimensional correlation spectroscopy are used to explore the data in detail. It has been found that the molecular solvents can interact with TFSI- (mainly with S=O and weakly with S–N–S group). AN interacts feebly with BMPyrr+ as compared with the strong interaction of DMSO. The strength of the interactions depends on the electron donating ability of the solvent. Upon mixing, hydrogen bonds regarding C−Hs in cation and S–N–S in anion are weakened, while that regarding S=O in anion is strengthened. Among the C−Hs which are connected directly with the N of the cation, C1−H is the main interaction site for both DMSO and AN. This means that C1−H is the most acidic hydrogen in pyrrolidinium cation.

Performance of solid state supercapacitors based on polymer electrolytes containing different ionic liquids

Abstract Four Ionic Liquid based Polymer Electrolytes (IL-b-PE) were prepared by blending a Polymeric Ionic Liquid, Poly(diallyldimethylammonium) bis(trifluoromethanesulfonyl)imide (PILTFSI), with four different ionic liquids: 1-butyl-1-methylpyrrolidinium bis(trifluoromethanesulfonyl)imide (PYR14TFSI) (IL-b-PE1), 1-butyl-1-methylpyrrolidinium bis(fluorosulfonyl)imide (PYR14FSI) (IL-b-PE2), 1-(2-hydroxy ethyl)-3-methylimidazolium bis(trifluoromethylsulfonyl)imide (HEMimTFSI) (IL-b-PE3), and 1-Butyl-1-methylpyrrolidinium dicyanamide, (PYR14DCA) (IL-b-PE4). Physicochemical properties of IL-b-PE such as ionic conductivity, thermal and electrochemical stability were found to be dependent on the IL properties. For instance, ionic conductivity was significantly higher for IL-b-PE2 and IL-b-PE4 containing IL with small size anions (FSI and DCA) than IL-b-PE1 and IL-b-PE3 bearing IL with bigger anion (TFSI). On the other hand, wider electrochemical stability window (ESW) was found for IL-b-PE1 and IL-b-PE2 having ILs with electrochemically stable pyrrolidinium cation and FSI and TFSI anions. Solid state Supercapacitors (SCs) were assembled with activated carbon electrodes and their electrochemical performance was correlated with the polymer electrolyte properties. Best performance was obtained with SC having IL-b-PE2 that exhibited a good compromise between ionic conductivity and electrochemical window. Specific capacitance (Cam), real energy (Ereal) & real power densities (Preal) as high as 150 F g−1, 36 Wh kg−1 & 1170 W kg−1 were found at operating voltage of 3.5 V.

Further property of ionic liquids: Hildebrand solubility parameter from new molecular thermodynamic model

A molecular thermodynamic-based approach has been previously employed to correlate the surface tension of ionic liquids (ILs). This paper aims to calculate further property of ILs, the solubility parameter of 27 ILs having imidazolium, pyrrolidinium, pyridinium, phosphonium, piperidinium and ammonium cations by the help of that approach along with an ion contribution-based equation of state (EOS). The proposed model calculates the internal pressure of ILs using a statistical mechanical expression and subsequently their solubility parameters through a simple relation. In this respect, contributions to internal pressure from the hard-sphere repulsion, Lennard-Jones dispersion force, and columbic interactions are considered and assumed to be additive in the development of the model. The performance of the proposed model is checked against the literature solubility parameters of ILs over temperature range within 298–358K. The proposed model has a sound basis of statistical-mechanics which incorporates contributions arising from the hard-sphere repulsion, Lennard-Jones dispersion forces. Further, the electrostatic interaction is taken into account using the mean spherical approximation (MSA). The outcomes of our model are also compared with those obtained based on the vaporization enthalpies and molar volumes, for which their values are available in literature. Generally, the new molecular model represents accurately the solubility parameters of studied ILs with uncertainty of the order of ±2.33%. The miscibility of some non-polar and polar hydrocarbons in ILs is also investigated by the use of their solubility parameters and Flory–Huggins interaction parameter.

Automated cytochrome c oxidase bioassay developed for ionic liquids’ toxicity assessment

A fully automated cytochrome c oxidase assay resorting to sequential injection analysis (SIA) was developed for the first time and implemented to evaluate potential toxic compounds. The bioassay was validated by evaluation of 15 ionic liquids (ILs) with distinct cationic head groups, alkyl side chains and anions. The assay was based on cytochrome c oxidase activity reduction in presence of tested compounds and quantification of inhibitor concentration required to cause 50% of enzyme activity inhibition (EC50). The obtained results demonstrated that enzyme activity was considerably inhibited by BF4 anion and ILs incorporating non-aromatic pyrrolidinium and tetrabutylphosphonium cation cores. Emim [Ac] and chol [Ac], on contrary, presented the higher EC50 values among the ILs tested.The developed automated SIA methodology is a simple and robust high-throughput screening bioassay and exhibited good repeatability in all the tested conditions (rsd<3.7%, n=10). Therefore, it is expected that due to its simplicity and low cost, the developed approach can be used as alternative to traditional screening assays for evaluation of ILs toxicity and identification of possible toxicophore structures. Additionally, the results presented in this study provide further information about ILs toxicity.

Preparation, Characterization, and Structure Trends for Graphite Intercalation Compounds Containing Pyrrolidinium Cations

New graphite intercalation compounds (GICs) containing N,N-n-alkyl substituted pyrrolidinium cation intercalates (Pyn.m, n, m = alkyl chain lengths) are obtained via cationic exchange from stage-1 donor-type GIC [Na(ethylenediamine)1.0]C15. Powder X-ray diffraction and thermogravimetric analyses are used to determine the GIC structures and compositions. [Py4.8]C47·0.71DMSO and [Py8.8]C48 with intercalate monolayers are obtained as stage-1 GICs with gallery expansions of 0.48 nm, whereas [Py1.18]C47 and [Py12.12]C80·0.25DMSO form stage-1 GICs with intercalate bilayers and gallery expansions of 0.81 nm. The gallery dimensions require that alkyl chain substituents orient parallel to the encasing graphene sheets. Smaller intercalate cations such as Py1.4, Py4.4, and Py1.8 either form high-stage GICs or do not form stable intercalation compounds. These results, along with those reported for graphite intercalation of other quaternary ammonium cations, indicate trends in graphite chemistry where larger intercala...

Designer Ionic Liquids for Reversible Electrochemical Deposition/Dissolution of Magnesium.

Chelating ionic liquids (ILs), in which polyether chains are pendent from the organic pyrrolidinium cation of the ILs (PEGylated ILs), were prepared that facilitate reversible electrochemical deposition/dissolution of Mg from a Mg(BH4)2 source. Mg electrodeposition processes in two specific PEGylated-ILs were compared against that in the widely studied N-butyl-N-methylpyrrolidinium bis(trifluoromethylsulfonyl)imide ionic liquid (BMPyrTFSI). The two chelating IL systems (one with a pendent polyether chain with three ether oxygens, MPEG3PyrTFSI, and the other with a seven-ether chain, MPEG7PyrTFSI) showed substantial improvement over BMPyrTFSI for Mg electrodeposition/dissolution. The best overall electrochemical performance was in MPEG7PyrTFSI. X-ray diffraction (XRD), scanning electron microscopy (SEM), and energy dispersive X-ray spectroscopy (EDS) were used to characterize galvanostatically deposited Mg, revealing production of pure, dendrite-free Mg deposits. Reversible Mg electrodeposition was achieved with high Coulombic efficiency (CE) of 90% and high current density (ca. 2 mA/cm(2) for the stripping peak). Raman spectroscopy was used to characterize Mg(2+) speciation in the PEGylated ILs and BMPyrTFSI containing Mg(BH4)2 by study of Raman modes of the coordinated and free states of borohydride, TFSI(-), and polyether COC groups. Quantitative analysis revealed that the polyether chains can displace both TFSI(-) and BH4(-) from the coordination sphere of Mg(2+). Comparison of the different IL electrolytes suggested that these displacement reactions may play a role in enabling Mg deposition/dissolution with high CE and current density in these PEGylated IL media. These results represent the first demonstration of reversible electrochemical deposition/dissolution of Mg in an ionic liquid specifically designed with this task in mind.

ChemInform Abstract: Ionic Liquids as an Electrolyte for the Electro Synthesis of Organic Compounds

AbstractReview: 160 refs.

Physicochemical and electrochemical properties of a new series of protic ionic liquids with N-chloroalkyl functionalized cations

Six new protic ionic liquids (PILs) based on N-chloroalkyl functionalized morpholinium, piperidinium, pyrrolidinium and alkylammonium cations, with bis[(trifluoromethyl)sulfonyl]imide as counter-ion, were synthesized by a metathesis reaction.

Hydrophilic interaction liquid chromatography for separation and determination of pyrrolidinium ionic liquid cations

The separation and detection of pyrrolidinium cations by hydrophilic interaction liquid chromatography with indirect ultraviolet detection.

Novel functionalized ionic liquid with a sulfur atom in the aliphatic side chain of the pyrrolidinium cation

A novel ionic liquid, never reported in literature until now, was properly designed, synthesized and preliminary investigated. This material was prepared combining the N-methylpyrrolidinium cation (PYR1(2S1))+, exhibiting a sulfur atom in the alkyl side chain, with the bis(trifluoromethanesulfonyl)imide anion, (TFSI)−, to be addressed as safer electrolyte component for sulfur-based battery systems. The presence of sulfur within the cation side chain was found to prevent the crystallization of the ionic liquid even in the presence of lithium salt. Cyclic voltammetries have clearly indicated that Li+ cation exhibits good mobility and is reversibly plated/stripped in PYR1(2S1)TFSI–LiTFSI electrolytes with high efficiency.

Alkaline Chemical Stability of Polymerized Ionic Liquids with Various Cations

The success of long-lasting low-cost (nonplatinum) alkaline fuel cells is dependent on the development of anion exchange membranes (electrolyte separator) with high alkaline chemical stability. In this study, a series of methacrylate-based polymerized ionic liquids (PILs) were synthesized with various covalently attached cations: butylimidazolium, butylmethylimidazolium, trimethylammonium, pentamethylguanidinium, butylpyrrolidinium, and trimethylphosphonium. The alkaline chemical stability of these PILs was examined in tandem with their analogous ionic salts: 1-butyl-3-methylimidizolium chloride, 1-butyl-2,3-dimethylimidazolium chloride, tetramethylammonium chloride, benzyltrimethylammonium chloride, hexamethylguanidinium chloride, 1,1-butylmethylpyrrolidinium chloride, and tetramethylphosphonium chloride. The degradation mechanisms and extent of degradation were quantified using 1H NMR spectroscopy at various pHs (in D2O), and temperature. The PILs with imidazolium and pyrrolidinium cations showed enhanc...

Hydrophilic interaction liquid chromatography with indirect ultraviolet detection for the separation and quantification of pyrrolidinium ionic liquid cations

Abstract A method of hydrophilic interaction liquid chromatography with indirect ultraviolet detection was developed to determine three pyrrolidinium ionic liquid cations, i.e . N -methyl- N -ethyl pyrrolidinium cation ([MEPy] + ), N -methyl- N -propyl pyrrolidinium cation ([MPPy] + ) and N -methyl- N -butyl pyrrolidinium cation ([MBPy] + ). Chromatographic separation was achieved on a hydrophilic column using imidazolium ionic liquids and organic solvents as the mobile phase. The effects of the background ultraviolet absorption reagents, the imidazolium ionic liquids, detection wavelength, organic solvents, column temperature and the pH value of the mobile phase on the separation and determination of pyrrolidinium cations were investigated and the retention behaviors in hydrophilic interaction chromatography were discussed. The optimized chromatographic conditions were selected. Under the optimal conditions, the detection limits ( S / N = 3) for [MEPy] + , [MPPy] + and [MBPy] + were 0.59, 0.53 and 0.46 mg/L, respectively. The method has been successfully applied to the determination of the three ionic liquids synthesized in our chemistry laboratory. This research results may improve the analytical method of ionic liquid cations.

On the Mechanism of Electrochemical Reduction of Niobium Halides in Ionic Liquids

In this paper we will discuss possible mechanisms of the charge transfer for the reduction of Nb halides in ionic liquids with pyrrolidinium cations. The reduction sequence starts from Nb(V) and seems to be relatively complex. Our experimental approach is mainly based on voltammetry combined with in-situ microgravimetry (quartz crystal microbalance) to study the mass-charge balance of the reduction process. There is strong indication for the occurance of at least one intermediate species, probably Nb(III). This intermediate can be detected in rotating ring disk electrode experiments. The rate constants of the individual charge transfer steps can be estimated from square wave voltammetry.

Electrochemical Model for Ionic Liquid Electrolytes in Lithium Batteries

ABSTRACT Room temperature ionic liquids are considered as potential electrolytes for high performance and safe lithium batteries due to their very low vapor pressure and relatively wide electrochemical and thermal stability windows. Unlike organic electrolytes, ionic liquid electrolytes are molten salts at room temperature with dissociated cations and anions. These dissociated ions interfere with the transport of lithium ions in lithium battery. In this study, a mathematical model is developed for transport of ionic components to study the performance of ionic liquid based lithium batteries. The mathematical model is based on a univalent ternary electrolyte frequently encountered in ionic liquid electrolytes of lithium batteries. Owing to the very high concentration of components in ionic liquid, the transport of lithium ions is described by the mutual diffusion phenomena using Maxwell-Stefan diffusivities, which are obtained from atomistic simulation. The model is employed to study a lithium-ion battery where the electrolyte comprises ionic liquid with mppy + (N-methyl-N-propyl pyrrolidinium) cation and TFSI − (bis trifluoromethanesulfonyl imide) anion. For a moderate value of reaction rate constant, the electric performance results predicted by the model are in good agreement with experimental data. We also studied the effect of porosity and thickness of separator on the performance of lithium-ion battery using this model. Numerical results indicate that low rate of lithium ion transport causes lithium depleted zone in the porous cathode regions as the porosity decreases or the length of the separator increases. The lithium depleted region is responsible for lower specific capacity in lithium-ion cells. The model presented in this study can be used for design of optimal ionic liquid electrolytes for lithium-ion and lithium-air batteries.

Effects of variation in chain length on ternary polymer electrolyte – Ionic liquid mixture – A molecular dynamics simulation study

Molecular dynamics (MD) simulations of ternary polymer electrolyte – ionic liquid mixtures are conducted using an all-atom model. N-alkyl-N-methylpyrrolidinium bis(trifluoromethylsulfonyl)imide ([CnMPy][TFSI], n = 1, 3, 6, 9) and polyethylene oxide (PEO) are used. Microscopic structure, energetics and dynamics of ionic liquid (IL) in these ternary mixtures are studied. Properties of these four pure IL are also calculated and compared to that in ternary mixtures. Interaction between pyrrolidinium cation and TFSI is stronger and there is larger propensity of ion-pair formation in ternary mixtures. Unlike the case in imidazolium IL, near neighbor structural correlation between TFSI reduces with increase in chain length on cation in both pure IL and ternary mixtures. Using spatial density maps, regions where PEO and TFSI interact with pyrrolidinium cation are identified. Oxygens of PEO are above and below the pyrrolidinium ring and away from the bulky alkyl groups whereas TFSI is present close to nitrogen atom of CnMPy. In pure IL, diffusion coefficient (D) of C3MPy is larger than of TFSI but D of C9MPy and C6MPy are larger than that of TFSI. The reasons for alkyl chain dependent phenomena are explored.

Probing the Physical Properties, Synthesis and Cellulose Dissolution Ability of Dialkyl Phosphate Ionic Liquids

GRAPHICAL ABSTRACT

Crystal Structure and Magnetic Property Studies of a Novel Hybrid Compound (C6H16N2) CoCl4

1-(2Aminoethyl) pyrrolidinium tetrachlorocobaltat (C6H16N2) CoCl4 has been prepared and analyzed by X-ray diffraction. The compound crystallizes in the orthorhombic system with space group P212121. The unit cell dimensions are a= 7.3279(13), b= 13.051(2) and c= 13.831(2) A with Z= 4. The crystal structure of this salt was solved by Patterson methods and refined by full-matrix least squares on F 2 to the final values of R=0.0486 and wR =0.1347. The structure consists of diprotonated 1-(2aminoethyl) pyrrolidinium cations and monomeric CoCl $_{4}^{2-}$ These entities are interconnected by means of hydrogen bonding contacts forming a threedimensional network. Magnetization was used to investigate the magnetic properties. This compound exhibits an antiferromagnetic (AFM) to paramagnetic (PM) phase transition at a temperature (T N) lower than 2 K. The values of paramagnetic Curie–Weiss temperature (𝜃 cw) and the exchange parameter (J/ K B) emphasize the existence of an antiferromagnetic interaction between the neighboring cobaltions.

Discovering less toxic ionic liquids by using the Microtox® toxicity test

New Microtox® toxicity data of 16 ionic liquids of different cationic and anionic composition were determined. The ionic liquids 1-butyl-1-methylpyrrolidinium trifluoromethanesulfonate, [BMPyr+][TFO-], 1-butyl-1-methylpyrrolidinium chloride, [BMPyr+][Cl−], hydroxypropylmethylimidazolium fluoroacetate, [HOPMIM+][FCH2COO−], and hydroxypropylmethylimidazolium glycolate [HOPMIM+][glycolate−] were found to be less toxic than conventional organic solvent such as chloroform or toluene, accoding the Microtox® toxicity assays. The toxicity of pyrrolidinium cation was lower than the imidazolium and pyridinium ones. It was found that the inclusion of an hydroxyl group in the alkyl chain length of the cation also reduce the toxicity of the ionic liquid. To sum up, the Microtox® toxicity assays can be used as screening tool to easily determined the toxicity of a wide range of ionic liquids and the toxicity data obtained could allow the obtention of structure–toxicity relationships to design less toxic ionic liquids.

Electrochemical preparation of palladium nanoparticles in bis(trifluoromethylsulfonyl)amide ionic liquids consisting of pyrrolidinium cations with different alkyl chain lengths

Electrochemical preparation of palladium nanoparticles has been investigated in the bis(trifluoromethylsulfonyl) amide (TFSA–) ionic liquids composed of 1-butyl-1-methypyrrolidinium (BMP+), 1-hexyl-1-methylpyrrolidinium (HMP+) and 1-decyl-1-methylpyrrolidinium (DMP+) containing [PdBr4]2–. Cathodic reduction of [PdBr4]2– on a carbon electrode below –2.2V vs. Ag|Ag(I) in the ionic liquids resulted in formation of palladium nanoparticles, which were confirmed by transmission electron microscopy and electron diffraction. The average particle sizes of the nanoparticles obtained at –2.6V in BMPTFSA, HMPTFSA and DMPTFSA were 2.9±0.6, 3.0±0.8 and 3.2±0.8nm, respectively, indicating the average particle size was slightly dependent on the ionic liquid. The nanoparticles dispersed in the ionic liquids are considered to form by inhibition of crystal growth with the organic cations accumulated on the negatively polarized electrode surface.

Ionic liquids as an electrolyte for the electro synthesis of organic compounds.

The use of ionic liquids (ILs) as a solvent and an electrolyte for electro organic synthesis has been reviewed. To date several ILs exist, however the ILs based on tetraalkylammonium, pyrrolidinium, piperidinium and imidazolium cations with BF4(-), PF6(-), and TFSI anions have been widely used and explored the most. Electro organic synthesis in ionic liquid media leading to the synthesis of a wide range of organic compounds has been discussed. Anodic oxidation or cathodic reduction will generate radical cation or anion intermediates, respectively. These radicals can undergo self coupling or coupling with other molecules yielding organic compounds of interest. The cation of the IL is known to stabilize the radical anion extensively. This stabilization effect has a specific impact on the electrochemical CO2 reduction and coupling to various organics. The relative stability of the intermediates in IL leads to the formation of specific products in higher yields. Electrochemical reduction of imidazolium or thiazolium based ILs generates N-heterocyclic carbenes that have been shown to catalyze a wide range of base or nucleophile catalyzed organic reactions in IL media, an aspect that falls into the category of organocatalysis. Electrochemical fluorination or selective electrochemical fluorination is another fascinating area that delivers selectively fluorinated organic products in Et3N·nHF or Et4NF·nHF adducts (IL) via anodic oxidation. Oxidative polymerization in ILs has been explored the most; although morphological changes were observed compared to the conventional methods, polymers were obtained in good yields and in some cases ILs were used as dopants to improve the desired properties.