Tetraethylammonium Cations Research Articles

Reversible storage of tetraethyl ammonium cation in CFx-based cathode

Carbon fluorides (CFx) are considered as the potential cation storage materials in alkali metal-based battery systems because of the high theoretical specific capacity (865 mAh g-1 when x = 1). However, the reversibility of cathode reaction is seriously disturbed by the strong metal-fluorine interactions among the electrode products (e.g., LiF). By contrast, the relatively weak N-F bond makes the CFx-based battery system using quaternary ammonium cation (QAA+) a promising alternate, but the electrode mechanism between CFx and QAA+is little understood yet. In this work, tetraethylammonium cation (TEA+) is employed as the charge carrier using the electrolyte solution of sulfolane (SL) for CFx cathode. The CF0.56 electrode exports 710 mAh g-1 during the initial TEA+-CF reaction, and the electrode product (TEAF) can be decomposed under elevated potential that yields amorphous carbon fluoride and a reversible capacity of ∼300 mAh g-1 can be reached in the subsequent galvanostatic charge-discharge cycles. The TEAF product is non-crystallizable that exists in a sticky form on the surface of electrode, which contributes to an improved electrode structural stability while also leads to an unsatisfactory performance of the amorphous carbon fluoride with large number of superficial active sites. The electrode mechanism and the mechanical property of electrode interface are discussed in depth by in-situ Raman and electrochemical quartz crystal microbalance (EQCM) methods.

Creation of spin switching in graphene oxide-based hybrid film materials with an anionic Fe(III) 5Cl-salicyaldehyde-thiosemicarbazone complex.

The present article describes the synthesis of hybrid composite film materials formed during the self-assembly process through non-covalent interactions of graphene oxide (GO) nanosheets with salt 1, represented by an anionic spin-crossover complex [FeIII(5Cl-thsa)2]- (5Cl-thsa - 5-chlorosalicylaldehyde thiosemicarbazone) and the organic tetraethylammonium cation [Et4N]+. The insertion of the salt 1 molecules into the interlayer space of GO nanosheets with the subsequent formation of a hybrid material GO-1 was observed. The film of the hybrid material GO-1 was characterized by scanning electron and confocal laser microscopy, EDX and XPS analysis, IR, Raman and 57Fe Mössbauer spectroscopy, dc magnetic measurements, and powder X-ray diffraction. Comparison of the magnetic properties of salt 1 and a film of the hybrid material GO-1 demonstrated a significant influence of the GO nanosheets matrix on the completeness of spin transition and showed a slight shift of the hysteresis loop by 1 K in the temperature range of 200-230 K. DFT calculations showed an important role of the organic cation [Et4N]+ in the process of adsorption of the spin-crossover anion [FeIII(5Cl-thsa)2]- on the GO nanosheet surface.

Dynamical Janus Interface Design for Reversible and Fast-Charging Zinc-Iodine Battery under Extreme Operating Conditions.

Aqueous zinc (Zn) iodine (I2) batteries have emerged as viable alternatives to conventional metal-ion batteries. However, undesirable Zn deposition and irreversible iodine conversion during cycling have impeded their progress. To overcome these concerns, we report a dynamical interface design by cation chemistry that improves the reversibility of Zn deposition and four-electron iodine conversion. Due to this design, we demonstrate an excellent Zn-plating/-stripping behavior in Zn||Cu asymmetric cells over 1000 cycles with an average Coulombic efficiency (CE) of 99.95%. Moreover, the Zn||I2 full cells achieve a high-rate capability (217.1 mA h g-1 at 40 A g-1; C rate of 189.5C) at room temperature and enable stable cycling with a CE of more than 99% at -50 °C at a current density of 0.05 A g-1. In situ spectroscopic investigations and simulations reveal that introducing tetraethylammonium cations as ion sieves can dynamically modulate the electrode-electrolyte interface environment, forming the unique water-deficient and chloride ion (Cl-)-rich interface. Such Janus interface accounts for the suppression of side reactions, the prevention of ICl decomposition, and the enrichment of reactants, enhancing the reversibility of Zn-stripping/-plating and four-electron iodine chemistry. This fundamental understanding of the intrinsic interplay between the electrode-electrolyte interface and cations offers a rational standpoint for tuning the reversibility of iodine conversion.

Two symmetric Schiff base complexes: Inhibition of cell proliferation, inducing apoptosis and suppressing migration

Two complexes [Cu4L4] (1) and [Zn2Cl4L]·2[N(CH2CH3)4] (2) are synthesized and characterized with UV–Vis, IR, PXRD and TGA using a symmetrical flexible Schiff base ligand 2,2′-(1,4-phenlenebis(nitrilomethylylidene)-bis(6- methoxyphenol) (H2L). Crystallographic analysis reveals that complex 1 is a mirror symmetric single molecule with a rhombic crossing structure linked by four Cu(II) ions and four ligands encircling each other. Complex 2 is a centrosymmetric single molecule with one ligand connecting two zinc chloride salts to form an anion framework with two tetraethylammonium cations to balance charge. Antiproliferative activity of both complexes against four cancer cells and two normal cells was investigated, and the results show that complex 2 had the strongest inhibitory effect on A549 cells with IC50 value much lower than cisplatin and lower toxicity to two normal cells. Mechanistic studies showed that complex 2 could induce apoptosis of A549 cells, and inhibit cell invasion and migration of SMMC-7721 cells and A549 cells at a low concentration effectively. This work could provide a basis for developing novel metal-based anticancer agents.

Dissolution dynamics of poly(4-hydroxystyrene) in potassium hydroxide (KOH) and sodium hydroxide (NaOH) aqueous solutions investigated by quartz crystal microbalance (QCM) method

Abstract The molecular size of alkaline cation has been reported to affect the dissolution of resist film in alkaline aqueous solution. However, the details are still unclear. In this study, the dissolution dynamics of poly(4-hydroxystyrene) (PHS) in potassium hydroxide (KOH) and sodium hydroxide (NaOH) aqueous solutions was investigated to clarify the effects of small alkaline cations on the dissolution dynamics of typical backbone polymer for chemically amplified resists by a quartz crystal microbalance (QCM) method. The temporal changes in the frequency and impedance of QCM substrates during development were measured. The maximum impedance reachable during development significantly exceeded that of the developer saturated with PHS unlike the case of tetramethylammonium and tetraethylammonium cations. This means that the PHS matrix near surface was swollen by decreasing the size of alkaline cation. By either increasing or decreasing the size of alkaline cation from tetramethylammonium and tetraethylammonium cations, the transient swelling layer became thick.

Reparameterization of Polarizable Force Fields for Studying Ion Transfer across Liquid-Liquid Interfaces.

We have developed a general scheme for refining classical polarizable molecular dynamics (MD) force fields that can accurately describe the molecular interactions in systems with liquid-liquid interfaces. While ab initio MD (AIMD) simulations can naturally describe molecular interactions, they are often so computationally expensive that simulating large system sizes and/or long time scales is usually infeasible. To resolve this, we parameterized efficient and accurate classical polarizable force fields that use AIMD reference data by minimizing both the relative entropy and the root mean squared deviation in atomic forces. We utilized our new multiscale models to study chloride ion transfer across the water-dichloromethane (DCM) interface with and without the tetraethylammonium cation as the phase-transfer catalyst. Our calculated free-energy barrier for the water-DCM interface is consistent with the other reported simulation results. We further analyzed the ion-transfer process by studying the hydration shell structures around the chloride ion and the ion-pair formation to better understand the mechanism. We observed that electronic polarizability is an important factor for the studied phase-transfer catalyst to lower the free-energy barrier of the ion transfer. Using the water-benzene interface system as an additional example, we show that our parameterization scheme provides a general route for modeling different liquid-liquid interface systems even when the experimental data or force field parameters are not readily available.

Seed-assisted crystallization of high-silica cubic and hexagonal faujasite polymorphs in the presence of the tetraethylammonium (TEA+) cation

Silica-rich Y (FAU topology) and EMC-2 (EMT topology) zeolites have been obtained in the presence of the tetraethylammonium (TEA+) cation as a structure-directing molecule and the corresponding protonic zeolites as seeds.

Mesoporous Beta zeolites with controlled distribution of Brønsted acid sites for alkylation of benzene with cyclohexene

The distribution of Brønsted acid sites in three-dimensional 12-membered pore channels of Beta zeolite was a decisive factor in the alkylation of benzene with cyclohexene. Here, the Brønsted acid site distribution in Beta zeolitic channels was precisely regulated by tuning the content of Na+ in crystallization system combined with tetraethylammonium cation, the Beta-55 with Brønsted acid sites exclusively located in straight channels (along a- and b-axis directions) was successfully synthesized by utilizing tetraethylammonium as the structure-directing agents without Na+ species, and the fraction of Brønsted acid sites in sinusoidal/straight channels of Beta zeolites can be accurately controlled by tailoring the content of Na+ in synthesis gel. Catalytic properties in the liquid alkylation between benzene and cyclohexene exhibited that Beta-55 zeolites with the Brønsted acid sites solely located in a-axis and b-axis channels showed the highest cyclohexene conversion, cyclohexylbenzene selectivity and longest lifetime in this reaction. In addition, the resultant Beta zeolites also exhibited low coke generation rate and robust regeneration performance in the alkylation reaction.

Dual-Functional Electrolyte Additive for Lithium–Sulfur Batteries Limits Lithium Dendrite Formation and Increases Sulfur Utilization Rate

Lithium–sulfur batteries (LSBs) have received great attention as promising candidates for next-generation energy-storage systems due to their high theoretical energy density. However, their practical energy density is limited by a large electrolyte-to-sulfur (E/S) ratio (>10 µL electrolyte/mg s), and their cycle performance encounters challenges from electrode passivation and Li dendrite formation. In this work, a dual-functional electrolyte additive of tetraethylammonium nitrate (TEAN) is presented to address these issues. NO3− as a high-donor-number (DN) salt anion can promote polysulfide dissolution, increase sulfur utilization, and alleviate electrode passivation. The tetraethylammonium cation can adsorb around Li protrusions to form a lithiophobic protective layer to inhibit the formation of Li dendrites. TEAN LSBs show improving capacity, cycling stability, and higher coulombic efficiency under lean electrolyte (5 μL electrolyte/mg s) conditions.

(Invited) Highly Stable, Crosslinked Polymer Membranes for Non-Aqueous Flow Batteries

Long-term energy storage is a crucial stepping stone for the introduction of renewable sources in the energy mix due to their intermittent nature. Non-aqueous Flow Batteries (NFBs) are expected to operate at higher potential differences in comparison to conventional aqueous systems, thus yielding an improved power density. However, among the several issues of NFBs, it is pivotal to develop ion-conducting separators stable in organic solvents.Here we present a new family of ionomers which proved promising as candidates to implement this crucial function. The ionomers are founded on the strong ionic interactions between the functionalities of a polyamide-based material (P) and a perfluorosulfonic acid macromolecule (N). The latter interactions establish crosslinks between the two starting macromolecules. Consequently, the polymeric structure of the final ionomer is reorganized, improving the mechanical properties and curtailing the swelling upon immersion in organic solvents.The membranes obtained from two of the proposed ionomers, labelled “P-N0.77” and “P-N0.89”, show a swelling < 7% after 1000 hours of immersion both in acetonitrile (ACN) and in a 1:1 vol./vol. mixture of ethylene carbonate and propylene carbonate (EC:PC). Upon exchanging the membranes with tetraethylammonium (TEA+) cations, a common benchmark mobile specie for NFBs, it is shown that: (i) P-N0.77 exhibits a conductivity of 0.4∙10-3 S∙cm-1 and 0.9∙10-3 S∙cm-1 at 25°C in 0.1 M TEA+ in ACN and 0.1 M TEA+ in EC:PC, respectively; and (ii) P-N0.89 shows a conductivity of 1.5∙10-3 S∙cm-1 and 0.5∙10-3 S∙cm-1 in the same conditions.These results suggest that the proposed materials are suitable for application in NFBs, opening the door to the long-term operation of these devices.

Transport of tetraethylammonium by the Malpighian tubules of Trichoplusia ni: Regional specialization and the influence of diet

Insect Malpighian tubules (MTs) play a major role in elimination of many potentially toxic compounds, including the organic cation tetraethylammonium (TEA). This paper examines transport of TEA by different segments of the MTs of the cabbage looper, Trichoplusia ni. The results show that the proximal ileac plexus (PIP) region of the MTs plays a dominant role in secretion of the organic cation TEA and that the rate of secretion is altered by feeding; principal cells of the proximal ileac plexus in tubules from larvae with full guts secreted TEA at higher rates than did the same cells in tubules of larvae in which the gut was empty. Michaelis-Menten analysis revealed that TEA secretion by the PIP was saturable and was blocked in a concentration-dependent manner by the organic cation cimetidine. For larvae reared from eggs on TEA-rich diet, higher concentrations of TEA in fluid secreted by the ileac plexus of tubules, and lower concentrations of TEA in the hemolymph, relative to larvae reared on control diet, is consistent with an upregulation of TEA transport in response to higher levels of dietary intake of an exogenous organic cation. The distal and proximal regions of the ileac plexus were also differentiated on the basis of transepithelial and basolateral membrane potentials and the influence of these electrical potentials on organic cation transport are discussed.

Multi-stimuli responsive (l-tartrato)oxovanadium(v) complex salt with ferroelectric switching and thermistor properties

A complex salt of tetraethylammonium cations and anions consisting of an inorganic {V4O8} core chelated with l-tartaric acid undergoes structural transformations triggered by changes in humidity and temperature, giving rise to switchable properties.

Supercrystal engineering of atomically precise gold nanoparticles promoted by surface dynamics.

The controllable packing of functional nanoparticles (NPs) into crystalline lattices is of interest in the development of NP-based materials. Here we demonstrate that the size, morphology and symmetry of such supercrystals can be tailored by adjusting the surface dynamics of their constituent NPs. In the presence of excess tetraethylammonium cations, atomically precise [Au25(SR)18]- NPs (where SR is a thiolate ligand) can be crystallized into micrometre-sized hexagonal rod-like supercrystals, rather than as face-centred-cubic superlattices otherwise. Experimental characterization supported by theoretical modelling shows that the rod-like crystals consist of polymeric chains in which Au25 NPs are held together by a linear SR-[Au(I)-SR]4 interparticle linker. This linker is formed by conjugation of two dynamically detached SR-[Au(I)-SR]2 protecting motifs from adjacent Au25 particles, and is stabilized by a combination of CH⋯π and ion-pairing interactions between tetraethylammonium cations and SR ligands. The symmetry, morphology and size of the resulting supercrystals can be systematically tuned by changing the concentration and type of the tetraalkylammonium cations.

Preferential and competitive role of hydrophilic/hydrophobic interactions quantifying amino acid-based ILs for papain stabilization

A plethora of amino acid based ionic liquid (AAIL) has been synthesized recently in order to thermally and structurally stabilize the proteins, however, critical impact of AAIL cations and anions hydrophilicity has been significantly ignored and subsided. Herein, the pivotal role of cations competitive hydrophilicity has been envisaged by investigating the proteolytic activity, structural stability, and alteration in microenvironment of papain in the presence of varying concentration of cholinium tryptophan ionic liquids [CHO][Trp]IL and tetraethylammonium tryptophan ionic liquids [TEA][Trp]IL. The proteolytic activity of papain in increasing concentration of [CHO][Trp]IL and [TEA][Trp]IL shows that at lower concentration of [CHO][Trp]IL more hydrophilic cholinium cation enhanced the papain activity from 100 to 131 %, however detrimental effects on the activity have been observed at lower concentration of [TEA][Trp]IL due to less hydrophilic nature of tetraethylammonium anions. Moreover, the highly interactive nature of [TEA][Trp]IL can be concluded by Fourier transmission infrared spectroscopy (FTIR). The UV–vis, steady state fluorescence and circular dichroism results also concluded the prowess of AAILs hydrophilic cation for stabilization nature. However, at higher concentration detrimental effects have been observed even for AAILs which are having hydrophilic cations. Thus, the study highlighted that [CHO][Trp]IL can enhance the activity and structure stability of papain more significantly while maintaining its surrounding microenvironment due to more hydrophilic nature of cholinium cation in contrast to [TEA][Trp]IL which consists of less hydrophilic tetraethylammonium cation. Moreover, with increase in the concentration of both AAILs, detrimental effects on the proteolytic activity and structural stability of papain have been observed. To differentiate further between the polar and non-polar interactions, protein-ligand molecular docking studies of papain and cations of both AAILs, have been performed using AutoDock Vina and AutoDock tools 1.5.7. The evaluated results corroborated the data obtained by FTIR, spectroscopic studies and enzymatic activity. From docking, activity and spectroscopic studies, it can be observed that at cholinium cation vehemently prefers polar interaction by forming hydrogen bonding with Arg-64 and Asp-158, however, tetraethylammonium cation longs for the polar interactions by forming van der Waals interactions with Ala-162, Val-133 and Val-207. Moreover, at the higher concentration of AAILs no extraordinary distinction between hydrophilic/hydrophobic natures has been observed and both AAILs denatured the papain at higher concentration irrespective of hydrophilic/hydrophobic nature of cation.

Synthesis of silica-rich chabazite using conventional Si and Al sources and the low-cost tetraethylammonium (TEA+) cation as structure directing molecule

High-silica zeolites with the CHA topology have been synthesized from conventional Si and Al sources in the presence of zeolitic seeds, and using the non-expensive tetraethylammonium (TEA+) cation as structure directing agent. Seeds with the CHA topology effectively enabled the crystallization of chabazite but the solid was difficult to obtain pure and almost systematically contaminated by zeolites with the GME framework topology. Better results were obtained when high-silica seeds with the FAU topology were added. Under those conditions, pure chabazite zeolites (CHA) with SiO2/Al2O3 > 13 could be obtained within a few days at 130 °C. Kinetic studies revealed that the zeolite chabazite was not formed directly from the D6R units of the faujasite seeds, as generally reported in the literature, but from the dissolution of an intermediate [TEA+]FAU zeolite that completely crystallized within less than 12 h. Moreover, pure chabazite zeolites (CHA) could be obtained with amounts of seeds as low as 2.5 wt %, that is, an order of magnitude lower than amounts previously reported in the literature.

Framework aluminum distribution in ZSM-5 zeolite directed by organic structure-directing agents: a theoretical investigation

The distribution of framework Al atoms in zeolite catalysts plays a significant role on dedicating the catalytic activity and product selectivity. Here, the relationship between framework Al distribution and organic structure-directing agents (OSDA) in ZSM-5 zeolite was investigated by the periodic density functional theory (DFT) and ab initio molecular dynamics (AIMD) simulations. It was found that OSDAs with alkyl chains, i.e., tetrapropylammonium (TPA+) and tetraethylammonium (TEA+) cations would lead to the Al atoms mainly distributed at the intersection. While OSDA with pyrazolium ring, i.e., 1,2,4-trimethylpyrazolium (124TMP+), would preferably direct the Al distributed at the sinusoidal channel of ZSM-5. Further energy analysis and electronic structure analysis showed that the Al distribution was not only determined by the Al intrinsic substitution ability of each T sites, but also dominated by the electrostatic interaction between OSDA and zeolite framework. These results indicated that the choice of OSDA used in the hydrothermal synthesis could strongly regulate the Al distribution in zeolite frameworks and further effectively determine the catalytic performance. Therefore, our work would provide a theoretical guidance for the precise design of zeolite catalysis.

Synthesis, structural characterization, and spectroscopic studies of bis-tetraethylammonium hexabromostannate [N(C2H5)4]2SnBr6

The structure of the new organic–inorganic hybrid compound (TEA)2SnBr6 (TEA+ = tetraethylammonium cation, [N(C2H5)4]+), synthesized by slow solvent evaporation at room temperature, has been determined by single-crystal X-ray diffraction analysis. At room temperature, it crystallizes in the trigonal-centrosymmetric space group R-3c (167) with parameters a = b = 10.7912(2) Å and c = 42.5740(11) Å, as expressed in the corresponding hexagonal cell. The structure of (TEA)2SnBr6 is built up of isolated SnBr6 octahedra (0D) arranged in a quasi-face-centered system (F).The Raman spectrum of (TEA)2SnBr6 has been acquired at room temperature in the wavenumber range 10–3600 cm−1. The results have been analyzed on the basis of group theory (predictions based on space group and compatibility relationships from free SnBr62− and TEA+ entities), comparison with studies of [N(CH3)4]2SnBr6, and ab initio calculations on TEA+, and are consistent with the structure.

Hydrophobic interaction of V12 bowl-type dodecavanadates with alkyl ammonium cations

The V12 dodecavanadate, [V12O32]4−, that is one of a dominant polyoxovanadate species in non-aqueous media, was investigated focusing on the interaction of alkyl chains on its counter cations. Although the presence of such a species is not reported in any biological system, the unique V12 bowl anions have exhibited a host-guest property to accommodate a biologically active anion such as a halide, a cyanide or an azide for its delivery to the system. The nonpolar interactions between alkyl chains and the surface oxygen atoms on the V12 is of significance in the host-guest property and the reactivity of the V12. In the solid state, a tetraethyl ammonium (TEA) cation approached 3 Å above the cavity of the V12 via non-covalent interaction showing the lid effect. This interaction induces a distortion of its flexible framework even in a solution state. From the solution state 51V NMR and IR spectra, the orientation of an azide in the cavity was altered between TEA and tetra-n-butyl ammonium (TBA) salts. The modification of the non-covalent interaction also affected an oxidative catalytic performance with H2O2. The rate of the formation of active species of a TEA salt of [V12O32(Br)]5− was shorter than that of a TBA salt.

Confinement of halide ions in Mg-Beta zeolites enables synergistic catalysis for CO2 cycloaddition

The confinement of metal-based matrix such as clusters, particles and even isolated single atoms in zeolite framework was intensively reported, while it was highly untoward to realize this goal for non-metallic ions due to the mutually-exclusive electrostatic interaction between the zeolite framework with negative charges and non-metallic anions. Herein, confinement of iodide ions in Mg-Beta zeolites (I@Mg-Beta) was successfully accomplished via the methodology of structural reconstruction, whose physicochemical property, channel connectivity as well as the location of Mg2+ and I- ions were investigated systematically. It was found that Mg2+ ions were located in the zeolitic framework and I- ions were mainly confined in Mg-Beta zeolite via the electrostatic interaction with tetraethylammonium cations. The establishment of structure–function relationship in CO2 cycloaddition reaction with epoxides indicated the presence of synergistic effect between framework Mg2+ ions and confined I- ions. The immobilisation of halide ions onto a zeolite support enabled it the recoverable ability from reaction systems, giving rise to relatively stable reusability. The catalytic transformation of CO2 cycloaddition with epoxides in this work was devoted to ameliorate environmental stress from anthropogenic greenhouse gases of CO2 by means of elaborately constructing metallosilicate zeolite confined non-metallic catalysts with dual functions.

Influence of tetraethylammonium cation on electrochemical CO2 reduction over Cu, Ag, Ni, and Fe surfaces

Enhancing the selectivity and activity of desired CO2 reduction products while suppressing hydrogen evolution reaction (HER) will facilitate the commercialization of electro-reduction of CO2 to hydrocarbons. Except for gold, polycrystalline surfaces of all transition metals used for the electrochemical CO2 reduction reaction (CO2RR) suffer from low CO2RR selectivities and activities at lower overpotentials. As ionic liquid cations stabilize key CO2RR intermediates and destabilize the HER intermediates, we studied the influence of tetraethylammonium (TEA+) cation on CO2RR and HER activities, experimentally, over transition metal electrodes (Cu, Fe, Ag, and Ni). We observed an enhancement in CO2RR activity and major CO2RR product formation in the presence of TEA+ cation on Cu and Ag. In addition, HER activity was enhanced on Ni and Fe surfaces but suppressed on Ag and Cu surfaces. Density functional theory (DFT) based computational studies were employed to rationalize these observations. Experimental and computational results suggest that the decreased activation energy for water dissociation enhanced the HER activity on Ni and Fe. Further, the increased activation energy for water dissociation suppressed HER activity on Cu and Ag. Moreover, the increase in *COO– (or CO2–⋅) binding energy in the presence of TEA+ cation is crucial for enhancing CO2RR activity and major CO2RR product formation on Cu and Ag. Thus, this study of the influence of TEA+ cation on CO2RR/HER activity over transition metal electrodes helps in exploring other ionic liquid cation-electrode combinations in terms of CO2–⋅ intermediate stabilization and water dissociation suppression for selective electrochemical CO2 reduction to fuels.