Quaternary Ammonium Ionic Liquids Research Articles

Visualizing and Understanding the Ionic Liquid-Mediated Polybromide Electrochemistry for Aqueous Zinc-Bromine Redox Batteries.

Aqueous zinc-bromine redox systems possess multiple merits for scalable energy storage. Applying bromine complexing agents shows effectiveness in alleviating the key challenge of ubiquitous crossover of reactive liquid bromine species, while the underlying microscopic mechanism requires a deep understanding to engineer better complexing electrochemistry. Herein, taking a series of quaternary ammonium ionic liquids (methyl4NBr, ethyl4NBr, propyl4NBr, and butyl4NBr) as a redox mediator model, operando optical monitoring was used to visualize the dynamic electrochemical behaviors, unveiling the ionic liquid-mediated polybromide electrochemistry with a distinct chain length effect. A longer chain length possesses a stronger electrostatic interaction in the complexing product to effectively capture Br2. Operando results reveal the liquid nature of the reversibly electrogenerated polybromide microdroplets in the butyl4NBr-added redox system, which promoted the Br3-/Br- conversion kinetics and alleviated the self-discharge for improved battery performance. This work provides direct evidence and new insights into complexing electrochemistry for advancing Zn-Br2 batteries.

Fabrication of Core–Shell Nanohybrid-Structured Hydrogel Sensors with Desirable Mechanical and Antibacterial Properties by Quaternary Ammonium Ionic Liquids with Different Chain Lengths

Fabrication of Core–Shell Nanohybrid-Structured Hydrogel Sensors with Desirable Mechanical and Antibacterial Properties by Quaternary Ammonium Ionic Liquids with Different Chain Lengths

MCM-41 supported quaternary ammonium ionic liquids as an effective heterogeneous catalyst for CO2 cycloaddition reaction

MCM-41 supported quaternary ammonium ionic liquids as an effective heterogeneous catalyst for CO2 cycloaddition reaction

Quaternary ammonium ionic liquids based on -SO3H with different alkyl chain lengths as electrolytes for fuel cells and the mechanism for proton transfer in ionic liquid

N, N, N-trimethyl propylsulphonate ammonium hydrosulfate (NC3SO3HHSO4) and N, N, N-trimethyl butyl sulphonate ammonium hydrosulfate (NC4SO3HHSO4) have been synthesized as electrolytes for the fuel cell. The results indicate that the single cell with NC3SO3HHSO4 exhibits a higher maximum power density (MPD) compared to that of the cell with NC4SO3HHSO4. The MPD achieved using NC3SO3HHSO4 and NC4SO3HHSO4 at 50°C were 48.5 mW·cm−2 and 38.2 mW·cm−2, respectively. The diffusion of ions becomes rapid for ionic liquids (ILs) due to their low viscosity, high conductivity, and chemical structure. Furthermore, quantum chemistry calculations provide detailed insights that elucidate the mechanisms underlying the improvement of cell performance. The proton transfer mechanisms in NC3SO3HHSO4 and NC4SO3HHSO4 are further investigated, including the proton transfer between H2SO4 and HSO4−, the proton transfer between cations and their corresponding neutral molecules, as well as the proton transfer between cations and anions. The cell performance improvement mainly depends on proton transfer between cations and their corresponding neutral molecules. The activation energy barriers for the NC3SO3H+-NC3SO3 complex, between the initial structures and the transition state, and between the final structures and the transition state, are 0.67 kcal·mol−1 and 1.55 kcal·mol−1, respectively. However, proton transfer from an NC4SO3H+ to an NC4SO3 does not occur. The difficulty in proton transfer may be attributed to the steric hindrance effect of cations. Therefore, it can be inferred that the steric hindrance effect of cations significantly impacts the mechanism of proton transfer.

Study on Electric Conductivity of Quaternary Ammonium Ionic Liquids

Study on Electric Conductivity of Quaternary Ammonium Ionic Liquids

Thermal stability and flammability of several quaternary ammonium ionic liquids

With the development of potential large-scale industrial application of quaternary ammonium ionic liquids in the fields of gas separation, high-temperature lubricants and even rocket propellants, deep investigations are required to reveal the possible hazards of thermal decomposition, the flammability and the hazardous gaseous products. In this study, the thermal stability of five typical quaternary ammonium ionic liquids, [N2222][NTF2], [N2222][PF6], [N2222]Br, [N4444]Br and [N4444][PF6], were studied using thermogravimetric analyser (TGA). The results show that the thermal stability of ionic liquids follows an order of [N2222][NTF2] > [N2222][PF6] > [N4444][PF6] > [N2222]Br > [N4444]Br, indicating that the thermal stability is obviously affected by the anion, with an order of [NTF2]− > [PF6]− > Br−. Besides, increasing the alkyl chain length in the cation will reduce the thermal stability. In addition, Fire Testing Technology (FTT) cone calorimeter was used to investigate the flammability and found that the longer alkyl chains of quaternary ammonium ionic liquids make great contribution on larger the total heat release, the peak value of heat releasing rate and shorter ignition time. Moreover, with the same cation, [N2222]Br and [N4444]Br were shortened the ignition time and produced larger amount of heat than [N2222][PF6] and [N4444][PF6], respectively. It clearly shows that the risk of fire is also affected by the anion, with an order of Br− > [PF6]− > [NTF2]−. Finally, the decomposition products were measured by thermogravimetry coupled with Fourier-transform infrared spectroscopy (TG-FTIR), and it is deduced that the nucleophilic Br− from [Nmmmm]Br (m = 2,4) and F− from the [NTF2]− and [PF6]− during decomposition will attack the alkyl chain of the cation, which generated gaseous products such as fluoroalkanes, bromoalkanes, olefins, etc.

P‐11.1: The interface engineering with quaternary ammonium ionic liquid enabling efficient blue perovskite light‐emitting diode

Metal halide perovskite light-emitting diodes (PeLEDs) have become a rising star in recent years. Interface plays an important role in the development of the PeLEDs performance. In this work, we demonstrate that the interface engineering with quaternary ammonium ionic liquid that could be used to improve the efficiency of the blue PeLEDs. We find the interface engineering can balance hole and electron injection. In addition, quaternary ammonium cation promotes the growth and nucleation of the blue perovskite emitter, improving its film morphology and reducing the occurrence of defects. The use of the ionic liquid interfacial layer is also helpful to inhibit the ion migration in the perovskite under forward bias operation. In conclusion, by exploring the quaternary ammonium ionic liquid interfacial layer, the luminous efficiency can be greatly improved.

One-step DMC synthesis from CO2 under catalysis of ionic liquids prepared with 1,2-propylene glycol

Three quaternary ammonium ionic liquids with strong nucleophilicity and distinctive structures were synthesized with high yield and purity based on the 1,2-propylene glycol anion (CH3CH2OHCH2O-) derived from transesterification products. Dimethyl carbonate (DMC) was in turn produced via a one-step reaction among propylene oxide (PO), CO2, and methanol (MeOH) by using the synthesized ionic liquids. The involved two-stage catalytic reaction of PO-CO2 cycloaddition and PC-MeOH transesterification was implemented without catalyst separation. Under mild conditions, the PO conversion reached 99.0%, with a PC yield of 99.0%, and a TON value of 119.5. Following the cycloaddition, MeOH was immediately introduced to achieve a PC conversion of 71.2%, a selectivity to DMC above 99%, and a TON value of 57.4 for the transesterification reaction. The influences of temperature as well as time for cycloaddition and transesterification were investigated. Cycloaddition of CO2 with various epoxides was also examined and all showed good performance. By taking advantage of the decomposability of as-prepared ionic liquids and the recyclability of decomposition products, a new catalyst circulation process was designed to complete the full cycle without introduction of any impurities into the product system.

Insight into the oil removal mechanism of quaternary ammonium ionic liquid microemulsions for oily sludge treatment

In this research, [N1,1,16EtOH]Cl was chosen as a surfactant to prepare IL microemulsions and used for effective treatment of oily sludge, which provided theoretical guidance for the efficient treatment of oily sludge.

Thermodynamic and Kinetic Effects of Quaternary Ammonium and Phosphonium Ionic Liquids on CO2 Hydrate Formation.

The paper elaborates the effects of ionic liquids (ILs) on the phase equilibrium temperature, induction time, gas consumption, gas consumption rate, and water to hydrate conversion in the presence of 0.25, 0.63, 0.95, 1.25, 3.75, 6.25, and 10.00 wt % ethyltributylphosphonium hexafluorophosphate ([P2444][PF6]), tributylhexylphosphonium hexafluorophosphate ([P6444][PF6]), tetraethylammonium bromide ([N2222]Br), tetraethylammonium bistrifluoromethanesulfonimide ([N2222][NTf2]), and tetraethylammonium hexafluorophosphate ([N2222][PF6]) under a pressure of 2 MPa. The results indicate that all five ILs could increase CO2 consumption and enhance the water to hydrate conversion. Compared with the pure water system, [P2444][PF6] and [P6444][PF6] shifted the phase equilibrium temperature of CO2 hydrates to a slightly higher temperature with reduced induction times by boosting CO2 hydrate nucleation, showing the dual function promotion effects. In contrast, [N2222]Br, [N2222][NTf2], and [N2222][PF6] shifted the phase equilibrium temperature of CO2 hydrates to a lower temperature and prolonged the induction time by slowing down CO2 hydrate nucleation. The inhibition effects of anions on CO2 hydrates follow an order of Br- > [NTf2]- > [PF6]-. Besides, the density functional theory and molecular dynamic calculations were conducted to explain the inconsistent influences of [N2222]Br and [N4444]Br on CO2 hydrate formation. It was found that the anion-cation interaction of [N2222]Br was stronger than that of [N4444]Br, and Br- in [N2222]Br is less likely to participate in the formation of hydrate cages in the [N2222]Br + H2O + CO2 system according to the intermolecular anion-water, anion-CO2, and water-water radial distribution function in [N2222]Br + H2O + CO2 and [N4444]Br + H2O + CO2 systems.

Chiral quaternary ammonium ionic liquids derived from natural dehydroabietylamine and their potential application in chiral molecular recognition

A series of chiral ionic liquids (CILs) based on a quaternary ammonium core substituted with (+)-dehydroabietylamine (DAA) moiety have been synthesized, which are used for the chiral discrimination of non-ionic racemic carboxylic acid and derivatives. The enantioselective recognition ability of the obtained DAA-CILs was investigated using (rac)-mandelic acid and its derivatives as substrates. The results showed that the choice of the anion was crucial for the chiral discrimination of these DAA-CILs. In general, bistrifluoromethanesulfonimide anion (NTf2-) resulted in the improvement and a broad spectrum of enantioselectivity of the CILs. The alkyl chain attached to the DAA group and quaternary ammonium cation was also responsible for the chiral discrimination, and the C3 or C4 carbon chain was favorable for the chiral molecule recognition ability of the CILs. A molecular simulation of the diastereomeric interactions between the selected [DAAPrTMA]NTf2 CIL and racemic α-methoxy mandelic acid (α-MPAA) achieved a well understanding of the chiral recognition mechanism. Additionally, the optical purity of α-MPAA could be detected via NMR analysis easily and quickly. This work leads us to develop new CILs with good molecular recognition ability, DAA-based quaternary ammonium salts.

Molecular Insight into the Ionic Conduction of Quaternary Ammonium and Phosphonium Cation-Based Ionic Liquids Using Dielectric and Spectroscopy Analyses.

We analyzed the primary properties of ionic liquids (ILs) comprising quaternary phosphonium cations and bis(trifluoromethylsulfonyl) amide anions and compared them with those of corresponding quaternary-ammonium-cation-based ILs. Broadband dielectric spectroscopy was used to confirm the coupling between the translational and orientational motions of ions, and our results demonstrated that the high ionic conductivity of the phosphonium-based ILs was attributed to their fast rotational dynamics. The differences between ILs with different cations were further evaluated using vibrational (Raman and terahertz) spectroscopy. The Raman spectroscopy data revealed that the cation structure affected the conformation and flexibility (conformational change) of the anion. Furthermore, terahertz spectroscopy allowed us to evaluate the relationship between ion transport and intermolecular interactions between the cation and anion of ILs.

(Digital Presentation) Rotating Ring-Disk Electrodes Studies on Oxygen Reduction Reaction at Hydrophobic Ionic Liquids Layer Modified Pt/C Catalyst

Polymer electrolyte fuel cells (PEFCs) are expected as one of the clean, highly effective energy conversion systems, and have been actively studied. Pt nanoparticles on carbon supports (Pt/C) are commonly used as a cathode catalyst for PEFCs, because of the high activity on oxygen reduction reaction (ORR). However, its durability in long term driving and high mass activity for ORR have not sufficiently fulfilled at the present. More improvements of Pt/C catalyst for ORR activity and the durability are required for the spread of PEFCs To improve the activity and durability of Pt/C, ionic liquids (ILs) modified catalysts, called Pt/C-Solid catalysis with an IL layer (SCILL) catalysts, have recently attracted much attention [1]. ILs are liquid salts around room temperature, which have high ionic conductivity and electrochemical stability. We focused on hydrophobic ionic liquids with quaternary phosphonium cations [2]. Quaternary phosphonium cations ionic liquids have higher ionic conductivity and hydrophobicity than quaternary ammonium ionic liquids with the same structure and the same counter ions. Because of interference in the oxygen reduction reaction on platinum by water, increasing the hydrophobicity of the surface is expected to improve the activity on Pt/C catalysis. Hence, by using the quaternary phosphonium cations ILs for Pt/C-SCILL catalysts, it promises to improve the ORR activities for the catalyst. On the other hand, proton conduction and oxygen permeation rate are also important factors for ORR activity enhancement. In this study, we report the ORR activity for Pt/C-SCILL catalysts with ILs composed of highly hydrophobic cations and hydrophobic anions. Quaternary phosphonium based ILs (PXXXY+TFSA-[alkyl chain X= 4 Y= 1, 12, 16]) were used for Pt/C-SCILL modified electrodes. Commercially available 20 wt% or 30 wt% Pt/C (Cabot, Vulcan XC-72R\U0001f12c) catalyst was used for bare Pt/C modified electrodes. The ultrasonicated Pt/C catalyst suspension was dropped on the mirror polished glassy carbon disk electrodes. Pt/C-SCILL modified electrodes were prepared by recasting the ILs-2-propanol solution on the bare Pt/C modified electrodes or adding ILs to the catalyst suspension. Moreover, the mixture of the ILs and bis(trifluoromethanesulfonyl)imide (HTFSA) were also examined. The thickness of the ILs layer was calculated relative to the BET surface area of the carbon support. A platinum wire and a reversible hydrogen electrode (RHE) were used as the counter and reference electrodes, respectively. CV and LSV were carried out in 0.1 M HClO4 solution under Ar (CV) or O2 (LSV) atmosphere, respectively. The Pt/C-SCILL catalyst was prepared by recasting (thin layers, ~0.4 nm) or mixing (thick layers, 1nm~) methods. In the case of the thin layer (~0.4 nm) of ILs, the ORR activity increased as the size of the cations increased. However, for the thicker (1 nm ~) ILs layers, the ORR activity was lower than for the bare Pt/C catalysts. It seems that the aprotic ILs interfered with the proton supply, making the four-electron reduction reaction of oxygen less likely to occur. Therefore, we attempted to supply protons to the thick ILs layer by mixing an ionic liquid with a proton source. HTFSA was dissolved in P444(12)TFSA, which showed relatively good ORR activity in thin film studies. The Pt/C-SCILL catalyst was prepared by adding the mixture with a catalyst dispersion. This proton mixing Pt/C-SCILL catalyst showed a significant improvement in ORR activity compared to bare Pt/C catalyst.

Understanding the coordination behavior of quaternary ammonium and phosphonium nitrate ionic liquids under gamma irradiation: A combined spectroscopic investigation

In the process of spent nuclear fuel reprocessing, it is very essential to investigate the radiation stability of the extracting phase.From the ionic liquid (IL) family, quaternary ammonium or phosphonium based ILs: methyltrioctylammonium nitrate ([N1888][NO3]) or trihexyl(tetradecyl)phosphonium nitrate ([P66614][NO3]) have many commendable features while being used as the solvent for the extraction and separation of the target metal ions from nuclear waste solution. In this context, a comparative investigation on the irradiation effect on the stability of [N1888][NO3] and [P66614][NO3] and their coordination ability towards acid and metal ion was furnished systematically. A marginal change in the extraction ability was acquired upon irradiation. The spectroscopictechniques such as UV–Visible, ATR-FTIR and fluorescence spectroscopy were employed to deduce the intrinsic role of the applied dose. The peak at ∼ 260 nm in UV–Visible spectra is broadened and red shifted upon irradiation for both ILs with substantial shift in [P66614][NO3]. FTIR spectra suggests the appearance of new peaks at 752 cm−1 upon radiation exposure for both ILs indicating the formation of degraded products of NO3– ion (bending vibration of NO2. radical) and - CH2 group (cleavage of - H. radical). A remarkable difference in the peak intensity and shape for [P66614][NO3] as compared to [N1888][NO3] confirms the radiation tolerance level of two ILs. For both irradiated and unirradiated ILs, the presence of water coordination was confirmed due to the peak at (bending mode of H2O), which later showed blue shift upon metal (or acid) loading.Luminescence patterns of Eu(III) in the irradiated ILs realizes an adequate quenching of Eu(III) emission in [P66614][NO3] in comparison to [N1888][NO3] which was less affected by the radiation. In all the spectroscopic evidences specify the vital role of NO3– anion in altering the radiation stability of ILs.

Separation and Enrichment of Selected Polar and Non-Polar Organic Micro-Pollutants—The Dual Nature of Quaternary Ammonium Ionic Liquid

In this study, the dual nature of quaternary ammonium ionic liquid–didecyldimethylammonium perchlorate, [DDA][ClO4], was evaluated. A novel and sensitive in situ ionic liquid dispersive liquid–liquid microextraction method (in situ IL-DLLME) combined with magnetic retrieval (MR) was applied to enrich and separate selected organic micro-pollutants, both polar and non-polar. The magnetic support relied on using unmodified magnetic nanoparticles (MNPs) prepared by the co-precipitation of Fe2+/Fe3+ (Fe3O4). The separation technique was on-lined with high-performance liquid chromatography (HPLC–DAD) verified by inverse gas chromatography. An anion exchanger, NaClO4, was added to form an in situ hydrophobic IL. The fine droplets of [DDA][ClO4], molded in aqueous samples, functioned as an extractant for isolating the studied compounds. Then the carrier MNPs were added to separate the IL from the water matrix. The supernatant-free sample was desorbed in acetonitrile (MeCN) and injected into the HPLC system. The applicability of [DDA][ClO4] as an extraction solvent in the MR in situ IL-DLLME method was checked by the selectivity parameters (Sij∞) at infinite dilution. The detection limit (LOD) ranged from 0.011 to 0.079 µg L−1 for PAHs and from 0.012 to 0.020 µg L−1 for benzophenones. The method showed good linearity with correlation coefficients (r2) ranging from 0.9995 to 0.9999.

Effect and mechanism of quaternary ammonium salt ionic liquid as a collector on desulfurization and desilication from artificial mixed bauxite using flotation

An quaternary ammonium ionic liquid (1401) was synthesized through tetradecyl dimethyl benzyl ammonium chloride and sodium isobutyl xanthate. Firstly, it was used as a flotation collector for reverse flotation of silicates and sulfur from diaspore-type high-sulfur and high silicon bauxite. Results demonstrated that maximum Al2O3 recovery of 50.8% were achieved, the sulfur content and the ratio of A/S were 0.65% and 3.24. The results showed the 1401 has a stronger collecting ability and selectivity for diaspore compared with dodecyl trimethyl ammonium chloride and N-butyl xanthate. The adsorption mechanism of 1401 on the surface of diaspore, kaolinite and pyrite was studied by Fourier transform infrared spectroscopy (FTIR), zeta potential and X-ray photoelectron spectroscopy (XPS) analysis. Results indicated that physical adsorption was occurred between the 1401 and the surface of diaspore, kaolinite, and the adsorption amount on the surface of kaolinite is much greater than that of diaspore. And the chemisorption between the 1401 and pyrite was occurred and suggested that 1401 was preferred to adsorb on the surface of diaspore and pyrite. These results indicate that the quaternary ammonium ionic liquid 1401 can be used as the collector for reverse flotation of diaspore, providing new ideas for the utilization of bauxite.

Extraction Behavior and Purification of Germanium Using an Undiluted Quaternary Ammonium Ionic Liquid in Combination with a Complexing Agent

Extraction Behavior and Purification of Germanium Using an Undiluted Quaternary Ammonium Ionic Liquid in Combination with a Complexing Agent

CO2-driven surface reconstruction in quaternary ammonium ionic liquid-propanol solutions

X-ray reflectivity (XRR) examined surface structures of hydrophobic quaternary ammonium ionic liquids, and their propanol mixtures were examined by XRR. The quaternary ammonium cations were [N(n)111]+ (n = 3, 4, and 6) and an anion was commonly bis(trifluoromethanesulfonyl)imide, [TFSI]−. The surface tension of pure [N(n)111][TFSI] increased with increasing n. Pure [N(n)111][TFSI] surface structures were stable in all gas atmospheres. The XRR of [N3111][TFSI]-1-propanol equilibrated showed CO2-induced surface roughness. Time-resolved XRR under CO2 of [N(n)111][TFSI]-propanol provided surface instabilities and a reconstruction process. The addition of 2-propanol to CO2 in [N4111][TFSI] promoted specific surface layering and a large amount of CO2 capture.

One-Pot Facile Synthesis of Double-Shelled Mesoporous Silica Microcapsules with an Improved Soft-Template Method for Sustainable Pest Management.

A controlled release formulation based on silica microcapsules is an ideal selection to improve both the effective utilization and duration of pesticides to decrease ecological damage. Herein, a simple and green method for preparing double-shelled microcapsules was developed using a newly prepared quaternary ammonium ionic liquid (IL) as the functional additive to entrap avermectin (Ave) in mesoporous silica nanospheres (MSNs) and tannic acid-Cu (TA-Cu) complex as the sealing agent to form the core-shell structure (Ave-IL@MSN@TA-Cu). The obtained microcapsules with an average size of 538 nm had pH-responsive release property and good stability in soil. The half-life of microcapsules (34.66 days) was 3 times that of Ave emulsifiable concentrate (EC) (11.55 days) in a test soil, which illustrated that microcapsules could protect Ave from rapid degradation by microorganisms by releasing TA, copper, and quaternary ammonium in the soil. Ave-IL@MSN@TA-Cu microcapsules had better nematicidal activity and antibacterial activity than Ave EC due to the synergistic effect of Ave, IL, and copper incorporated in the microcapsules. Pot experiments showed that the control efficacy of microcapsules was 87.10% against Meloidogyne incognita, which is better than that of Ave EC (41.94%) at the concentration of 1.0 mg/plant by the root-irrigation method after 60 days of treatment owing to the extended duration of Ave in microcapsules. The simple and green method for the preparation of double-shelled microcapsules based on natural quaternary ammonium IL would have tremendous potential for the extensive development of controlled release pesticide formulations.

Quaternary Ammonium Compounds (QACs) and Ionic Liquids (ILs) as Biocides: From Simple Antiseptics to Tunable Antimicrobials.

Quaternary ammonium compounds (QACs) belong to a well-known class of cationic biocides with a broad spectrum of antimicrobial activity. They are used as essential components in surfactants, personal hygiene products, cosmetics, softeners, dyes, biological dyes, antiseptics, and disinfectants. Simple but varied in their structure, QACs are divided into several subclasses: Mono-, bis-, multi-, and poly-derivatives. Since the beginning of the 20th century, a significant amount of work has been dedicated to the advancement of this class of biocides. Thus, more than 700 articles on QACs were published only in 2020, according to the modern literature. The structural variability and diverse biological activity of ionic liquids (ILs) make them highly prospective for developing new types of biocides. QACs and ILs bear a common key element in the molecular structure–quaternary positively charged nitrogen atoms within a cyclic or acyclic structural framework. The state-of-the-art research level and paramount demand in modern society recall the rapid development of a new generation of tunable antimicrobials. This review focuses on the main QACs exhibiting antimicrobial and antifungal properties, commercial products based on QACs, and the latest discoveries in QACs and ILs connected with biocide development.