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Owing to the diversity of structure and potential applications in the field of electrics, sensors, and light-emitting diodes, lead halide perovskites have attracted great attention in recent years. Especially those lead halide perovskites with non-centrosymmetric crystal structures usually exhibit nonlinear optical (NLO) characteristics, which may endow them photoelectricity switching functionality. In this work, a lead-based hybrid organic-inorganic perovskite (HOIP) material, trimethyliodomethylammonium lead trichloride (TMIM·PbCl3), is obtained on the basis of tetramethylammonium lead chloride through halogen substitution on the cation part. It shows dual-phase-transition behavior around 345 and 358 K, which is significantly improved. TMIM·PbCl3 crystallizes in the chiral space group, P212121, and shows a well-defined second harmonic generation (SHG) response, and good switching endurance, which makes it an excellent candidate for SHG switching material. This work highlights the importance of halogen substitution for crystal engineering and may pave way for the further exploration of the optoelectronic devices.

The effect of a series of tetramethylammonium salts with different counter anions on the photophysical properties of a chiral Eu(III) complex (Eu( D -facam) 3 ) was investigated. The aniondependent luminescence of the Eu(III) complex was observed, and particularly in the presence of acetate ions, an outstanding luminescence enhancement (>300 times) and induced circularly polarized luminescence ( g lum = -0.63) were obtained. The energy transfer process was then evaluated using key photophysical parameters, and it was found that the sensitisation efficiency of the Eu(III) complex significantly increased in the presence of tetramethylammonium acetate (TMAOAc). The interactions between Eu( D -facam) 3 and TMAOAc were confirmed by luminescence analysis, circular dichroism spectroscopy, Fourier transform infrared spectroscopy and mass spectral measurements.

A new metal–organic single crystals of tetramethylammonium cadmium nitrate (TMACN) have been grown by solution growth method. The grown TMACN crystals have been characterized by single-crystal X-ray diffraction (SCXRD) and powder X-ray diffraction analyses. Furthermore, TMACN crystals have been subjected to scanning electron microscope (SEM), Fourier transform infra-red, Fourier transform Raman, UV–Visible, and Vickers microhardness studies. The surface morphology has been investigated by SEM analysis. From UV–Visible analysis, the grown crystals have been optically transparent from 200 to 900 nm. The mechanical stability has been investigated by Vickers microhardness study. Time-dependent dielectric studies have been measured by LCR meter. The dielectric constant varies with increasing frequency observed using dielectric study. Photoluminescence spectral study give the information about the crystal which emits green emission.

Methoxy-prism[5]arene PrS[5]Me is demethylated by a supramolecularly assisted reaction. In the presence of a tetramethylammonium cation, PrS[5]Me is demethylated by BBr3 in high yield, while in its absence a 55/40 mixture of PrS[5]OH/PrS[6]OH is formed. The dealkylation of prismarenes, such as PrS[6]R (R = Et, nPr) and c-PrS[5]Me, can be easily obtained in high yields in the presence of BBr3.

Interaction of trimethylamine N-oxide (TMAO) with charged/uncharged moieties of proteins and lipids is an important elementary step toward the multifaceted biofunctions of TMAO. Using minimum area Raman difference spectroscopy (MA-RDS) of aqueous TMAO (1.0 M) in the presence of deuterated molecular hydrophobes (e.g., deuterated tetramethylammonium cation (d-TMA+) and tert-butylalcohol (d-TBA)), we show that TMAO exhibits two distinct motifs of interaction with the cationic (d-TMA+) and uncharged (d-TBA) hydrophobes. Specifically, the trimethylammonium moiety of TMAO undergoes van der Waals attraction with the tert-butyl group of d-TBA, which is governed by their mutual hydrophobic interaction with water. This makes their methyl groups less exposed to water. In contrast, for the cationic hydrophobe (d-TMA+), TMAO interacts electrostatically via its negatively charged-oxygen, which in turn orients the TMAO-methyls away from the hydrophobe (d-TMA+), keeping them exposed to water.

Crystal structures of tetramethylammonium salts of [XW18O60]9– anions (X = As3+, Sb3+) are described for the first time. The structures of ((CH3)4N)6H3[AsW18O60]·3.8H2O (1) and ((CH3)4N)6H2.5Na0.5[SbW18O60]· 7.7H2O (2) are determined by single crystal X-ray diffraction. In the structure of complex 2, the [β-SbW18O60]9– isomer is discovered for the first time.

Amine-containing adsorbents have been widely investigated for capturing CO₂ but suffer from rapid oxidative degradation. We recently reported that ppm-level metal impurities (Fe and Cu) in commercial amine polymers can accelerate the oxidative degradation of these amine-containing adsorbents, which can be suppressed by adding chelators such as phosphate. In the present study, we investigated the amine-stabilization effects of monocationic phosphate salts containing cations of different charge densities, such as Li⁺, Na⁺, tetramethylammonium (TMA⁺), and tetraethylammonium (TEA⁺). The results showed that phosphate salts containing organophilic cations of low charge densities can effectively stabilize amine polymers. Such organophilic phosphate salts might be better dispersed within the organic amine polymers and have a loosely associated ion-pair form, which is beneficial for binding with metal impurities. Consequently, the adsorbent stabilized with the most organophilic TEAH₂PO₄ exhibited unprecedentedly high stability; specifically, it showed a very minor decrease in CO₂ capacity (

The ambiguity in the behavior of water molecules around hydrophobic solutes is a matter of interest for many studies. Motivated by the earlier results on the dynamics of water molecules around tetramethylammonium (TMA) cation, we present the effect of temperature on the structure and angular jumps of water due to hydrophobicity using first principles molecular dynamics simulations. The average intermolecular distance between the central oxygen and four nearest neighbors is found to be the highest for water molecules in the solvation shell of TMA at 400 K, followed by the same at 330 K. The hydrogen bond (HB) donor–acceptor count, HB per water molecule, and tetrahedral order parameter suggests the loss of tetrahedrality in the solvation shell. Elevated temperature affects the tetrahedral parameter in local regions. The HB jump mechanism is studied for methyl hydrogen and water molecules in the solvation shell. Observations hint at the presence of dangling water molecules in the vicinity of the hydrophobic cation, and no evidence is found for the enhanced structural ordering of nearby water molecules.

Supramolecular derivatives of chlorostannate(IV) and -plumbate(IV) with {Cl2} units, Cat2{[MCl6](Cl2)x} (1–5; M = Sn, Pb, cat = 1-methylpyridinium (1-MePy), tetramethylammonium (TMA)) were prepared...

Mesoporous materials have been widely used in the adsorption of air pollutants because of their uniform pore structure and large specific surface area. In this study, hexadecyltrimethylammonium chloride and tetramethylammonium hydroxide pentahydrate were used as structure-directing agents, silica as a silicon source, and tetramethylammonium silicate as a functional group to prepare a mesoporous silica-based material (MSBM) by a designed hydrothermal reaction. The synthetic materials were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), Brunner-Emmet-Teller (BET), Fourier-transform infrared spectroscopy (FITR), and thermogravimetric analysis (TGA). The adsorption efficiency of MSBM for SO2 in simulated flue gas under different conditions was studied. The results showed that the structure of the MSBM was the hexagonally ordered MCM-41 structure. It had the characteristics of uniform appearance, large specific surface area, rich surface groups, and strong thermal stability. The static activity of SO2 in flue gas could reach 32.1 mg/g under optimal conditions, which was slightly inferior to activated carbon. Therefore, MSBM has great practical application potential in the treatment of SO2 in flue gas.

Mechanistic investigations on the intramolecular direct arylation of an indole-containing aryl bromide en route to the HCV NS5B inhibitor beclabuvir are reported. A combination of stoichiometric, k...

The crystal structures of methylammonium and dimethylammonium dihydrogenphosphite (MA⋅H2PO3, I2/a and DMA⋅H2PO3, P 2 1 / c $P{2}_{1}/c$ ) are built of infinite chains of hydrogen bonded H 2 P O 3 − ${\mathrm{H}}_{\mathrm{2}}\mathrm{P}{\mathrm{O}}_{\mathrm{3}}^{-}$ anions. The chains are connected by the ammonium cations via hydrogen bonding to di- (DMA⋅H2PO3) and triperiodic (MA⋅H2PO3) networks. Tetramethylammonium dihydrogenphosphite monohydrate (TMA⋅H2PO3⋅H2O) features temperature dependent dimorphism. The crystal structure of the high-temperature (HT, cubic P213) and low-temperature (LT, orthorhombic P212121) phases were determined at 150 and 100 K, respectively. The hydrogen bonding network in the HT phase is disordered, with H 2 P O 3 − ${\mathrm{H}}_{\mathrm{2}}\mathrm{P}{\mathrm{O}}_{\mathrm{3}}^{-}$ and H2O being located on a threefold axis and is ordered in the LT phase. On cooling, the point symmetry is reduced by an index of 3. The lost symmetry is retained as twin operations, leading to threefold twinning by pseudo-merohedry. The hydrogen-bonding networks of the HT and LT phases can be represented by undirected and directed quotient graphs, respectively.

Stimulus responsive materials can provide a variety of desirable properties in one equipment unit, such as optoelectronic devices, data communications, actuators, memories, sensors and capacitors. However, it remains a large challenge to design such stimulus responsive materials, especially functional materials having both dielectric switch and second harmonic generation (SHG). Here, a new stimuli-responsive switchable material [(CH3)3N(CH2)2Cl]2[Mn(SCN)4(H2O)2] was discovered as a potential second-harmonic generation (SHG) dielectric switch. It is worth noting that it has SHG characteristics before and after undergoing reversible high-temperature phase transitions. In this work, we successfully refined the tetramethylammonium cation to obtain a quasi-spherical cation, which is tetramethylchloroethylamine (TMCEM) cation. By substituting H with a halogen, the increased steric hindrance of the molecular makes energy barrier increased, resulting in the reversible high-temperature phase transition. At the same time, the interactions of quasi-spherical cations and [Mn(SCN)4(H2O)2]2− anions affect a non-centrosymmetric structure to induce the SHG effect. These findings provide a new approach to design novel functional switch materials.

Tetramethylammonium trifluoromethylselenate ([Me4N][SeCF3]) has been confirmed as an excellent precursor of selenofluorophosgene for amines in the preparation of selenocarbamoyl fluorides, selenoureas, and heterocycles under catalyst- and additive-free conditions. Reactions of [Me4N][SeCF3] with secondary amines at room temperature provided exclusively selenocarbamoyl fluorides in moderate to high yields, while the same reactions with primary amines afforded selenoureas in good yields. When [Me4N][SeCF3] was similarly mixed with amines containing adjacent amino, hydroxyl or thiol groups, five- and six-membered heterocycles were produced. The reaction featured simplicity, rapidness, high efficiency, a broad substrate scope, and good functional group tolerance, offering a convenient access to a variety of selenocarbonylated compounds, which were otherwise difficult to synthesize by other approaches.

For flow assurance applications, various chemicals are used in the oil and gas industry in order to mitigate corrosion. Among corrosion suppressing compounds, quaternary ammonium salts (QASs) find an exceptional usage as these relatively long chain compounds adsorb onto the surface of the pipeline. The formation of protective layer by adsorbing on the surface prevents corrosion. In this work, tetramethylammonium acetate (TMAAc) which is QAS is evaluated as a corrosion controlling compound in saline environment using weight loss method. The weight loss experiments are performed with the solution concentrations of TMAAc at 0.01, 0.5, 1, 2, 5 and 10 wt%. Corrosion rate values are determined at these concentrations. It is observed that the corrosion with the increase in concentration of TMAAc, corrosion rate is also increased. Rate of metal corrosion varies from 0.068 mm/yr to 0.176 mm/yr in the range of 0.01–10 wt%. The minimum value of corrosion rate is found to be 0.068 mm/yr at the sample concentration of 100 ppm. It is concluded that at lower concentrations, TMAAc can find its application as a commercial corrosion inhibitor.

So far, several publications have discussed the bonding concepts in polyhalides on a theoretical basis. In particular, the trichlorine monoanion is of great interest because its structure should be symmetrical and show two equidistant Cl−Cl bonds. However, apart from matrix‐isolation studies, only asymmetric trichlorine anions have been reported so far. Herein, the trichlorine monoanions in 2‐chloroethyltrimethylammonium trichloride [NMe3EtCl][Cl3], 1, tetramethylammonium trichloride [NMe4][Cl3], 2, and tetrapropylammonium trichloride [NnPr4][Cl3], 3, are analysed. High‐resolution X‐ray structures and experimental charge density analyses supported by periodic quantum‐chemical calculations provide insight into the influence of the crystalline environment on the structure of these [Cl3]− anions as well as into the progress of the bond formation between a dichlorine molecule and a Cl− anion., For the first time, the 3c–4e bond of a symmetric trichlorine anion [Cl]− was characterized by experimental charge density investigations and compared to two asymmetric cases. Quantum‐chemical DFT calculations for both periodic crystals and isolated molecules/ions flank those studies. There appears to be a smooth transition from the asymmetric to the symmetric compound.

Cube‐like double four‐ring (d4r) cages are among the most frequent building units of zeolites and zeotypes. In materials synthesised in fluoride‐containing media, the fluoride anions are preferentially incorporated in these cages. In order to study the impact of framework composition and organic structure‐directing agents (OSDAs) on the possible occurrence of local distortions of fluoride‐containing d4r cages, density functional theory (DFT) calculations and DFT‐based molecular dynamics simulations were performed for AST‐type zeotypes, considering four different compositions (SiO2, GeO2, AlPO4, GaPO4) and two different OSDA cations (tetramethylammonium [TMA] and quinuclidinium [QNU]). All systems except SiO2‐AST show significant deformations, with a pyritohedron‐like distortion of the d4r cages occurring in GeO2‐ and GaPO4‐AST, and a displacement of the fluoride anions towards one of the corners of the cage in AlPO4‐ and GaPO4‐AST. While the distortions occur at random in TMA‐containing zeotypes, they exhibit a preferential orientation in systems that incorporate QNU cations. In addition to providing detailed understanding of the local structure of a complex host‐guest system on the picosecond timescale, this work indicates the possibility to stabilise ordered distortions through a judicious choice of the OSDA, which might enable a tuning of the material's properties., Dynamic ions in small cages: The equilibrium position and dynamic behaviour of fluoride anions encapsulated in double four‐ring cages are investigated using ab initio molecular dynamics simulations. While the occurrence of local distortions depends on the framework composition, the organic cation determines whether they are randomly oriented or ordered.

The binding energies for cation-π complexation are underestimated by traditional fixed-charge force fields owing to their lack of explicit treatment of ion-induced dipole interactions. To address this deficiency, an explicit treatment of cation-π interactions has been introduced into the OPLS-AA force field. Following prior work with atomic cations, it is found that cation-π interactions can be handled efficiently by augmenting the usual 12-6 Lennard-Jones potentials with 1/r4 terms. Results are provided for prototypical complexes as well as protein-ligand systems of relevance for drug design. Alkali cation, ammonium, guanidinium, and tetramethylammonium were chosen for the representative cations, while benzene and six heteroaromatic molecules were used as the π systems. The required nonbonded parameters were fit to reproduce structure and interaction energies for gas-phase complexes from density functional theory (DFT) calculations at the ωB97X-D/6-311++G(d,p) level. The impact of the solvent was then examined by computing potentials of mean force (pmfs) in both aqueous and tetrahydrofuran (THF) solutions using the free-energy perturbation (FEP) theory. Further testing was carried out for two cases of strong and one case of weak cation-π interactions between druglike molecules and their protein hosts, namely, the JH2 domain of JAK2 kinase and macrophage migration inhibitory factor. FEP results reveal greater binding by 1.5-4.4 kcal/mol from the addition of the explicit cation-π contributions. Thus, in the absence of such treatment of cation-π interactions, errors for computed binding or inhibition constants of 101-103 are expected.

Organoboron compounds are essential reagents in modern C−C coupling reactions. Their synthesis via catalytic C−H borylation by main group elements is emerging as a powerful tool alternative to transition metal based catalysis. Herein, a straightforward metal‐free synthesis of aryldifluoroboranes from BF3 and heteroarenes is reported. The reaction is assisted by sterically hindered amines and catalytic amounts of thioureas. According to computational studies the reaction proceeds via frustrated Lewis pair (FLP) mechanism. The obtained aryldifluoroboranes are further stabilized against destructive protodeborylation by converting them to the corresponding air stable tetramethylammonium organotrifluoroborates., C−H activation: Indoles, pyrroles and indolenines undergo C−H borylation by boron trifluoride with assistance of base and thiourea additives.

To high efficiently remove H2S from low partial pressure coke oven gas (COG), a novel activator (tetramethylammonium arginine, [N1111][Arg]) was used to blend with N-methyldiethanolamine (MDEA) for the absorption of H2S. High concentrated [N1111][Arg]-MDEA aqueous solution was used as absorbent. Thermodynamic properties including absorption amount and H2S loading values were measured, then the kinetic apparent absorption rate was calculated based on the change of absorption amount with time. The removal efficiency of H2S in simulated COG was verified in tray towers. Compared with monoethanolamine (MEA)-MDEA and tetramethylammonium glycinate ([N1111][Gly])-MDEA aqueous solutions, [N1111][Arg]-MDEA aqueous solution takes advantages of higher absorption capacity, absorption rate and removal efficiency. Our results showed that the proposed absorbent has good industrial application prospect in coke oven gas desulfurization, because it achieved 100% removal of H2S in the tray tower containing only 4 sieve plates under high concentrated condition (water content < 45%), which may significantly decrease the energy consumption.

The heterobimetallic metallacrown (MC), (TMA)$_2${Mn(OAc)$_2$[12-MC$_{Mn(III)Cu(II)N(shi)}$-4](CH$_3$OH)}$\cdot$2.90CH$_3$OH, 1, where TMA$^+$ is tetramethylammonium, $^-$OAc is acetate, and shi$^{3-}$ is salicylhydroximate, consists of a Mn$^{II}$ ion captured in the central cavity and alternating unambiguous and ordered manganese(III) and copper(II) sites about the MC ring, a first for the archetypal MC structure design. DC-magnetometry characterization and subsequent simulation with the Spin Hamiltonian $$H = -J_1(\mathbf{s}_1+\mathbf{s}_3)\cdot\mathbf{s}_5-J_2(\mathbf{s}_2+\mathbf{s}_4)\cdot\mathbf{s}_5-J_3\sum_{i=1}^{4}\mathbf{s}_i\cdot\mathbf{s}_{i+1} + d(s_{z,1}^2 + s_{z,3}^2) + \mu_B\sum_{j=1}^5 g_j\mathbf{s}_j\cdot\mathbf{B}$$ indicates an S = 5/2 ground state and a sizable axial zero-field splitting on Mn$^{III}$. AC-susceptibility measurements reveal that 1 displays slow magnetization relaxation akin to single-molecule magnet (SMM) behavior.

A novel dual-template strategy was first proposed for the fabrication of mesoporous silica with hollow triangular prism morphology, using amino acid ionic liquid tetramethylammonium glycine ([N1111...

An improved kilogram-scale process of synthesis of nalbuphine was developed by investigating the critical parameters. Ten process-related impurities were identified, of which the source and control strategy was elucidated. Moreover, tetramethylammonium triacetoxyborohydride (Me4NBH­(OAc)3) was developed to reduce the imine and ketone in one pot. As a result, 6-β-epimer was significantly controlled to only 0.08% in the crude nalbuphine. The improved process was robust at kilogram scale in 60.4% overall yield with 99.95% high-performance liquid chromatography (HPLC) purity.

In this paper the objectives were not only to investigate new promising methods leading to a deep structural rearrangement of carboranes and metallacarboranes but also to try to fix, to isolate and to characterize the intermediates. At the same time considerable atten-tion is paid to the so-called "anti-wade" clusters formed during the reactions, the elec-tronic structure of which does not correspond to their actually observed geometry. It is shown that the interaction of 11-vertex monocarbon closo-carboundecaborane with tris(triphenylphosphine)ruthenium dichloride leads to a series of new metallacarborane complexes. For the first time it was possible to control the process of "polyhedral contrac-tion" of carborane {CB10} → (RuCB10} → {RuCB9} → {RuCB8} → {RuCB6} on the example of ruthenium complex and also to confirm experimentally each stage of the whole process. As a result of the reaction clusters of classical type and electron-deficient isocloso-/hypercloso-rutenacarborans {RuCB8}, {RuCB9} with 2n skeletal electrons were isolated.

The energy storage of supercapacitors can be enhanced by utilizing porous carbon electrodes with nanometer or even sub-nanometer sized pores that exhibit close match of the pore and ion size. In these highly confined regimes, ion diffusion barriers may be substantial, leading to a tradeoff between power output and energy storage. In this work, we utilize molecular dynamics simulations to quantify free energy barriers for ion diffusion through nanometer and sub-nanometer sized pores in carbon electrodes. We focus on prototypical electrolytes composed of trimethylethylammonium (TMEA+) and tetramethylammonium (TMA+) cations, and tetrafluoroborate ( BF 4 - ) anions, with both acetonitrile and 1,2-dichloroethane solvents. We quantify the dependence of diffusion barriers on nanopore width and pore length as a function of solvent and ion type. Our overarching conclusion is that sub-nanometer sized pores of 7.5–10 A diameter, as previously demonstrated to be optimal for energy storage, lie exactly at the limit of diffusion accessibility at low voltage. We show that nanopore accessibility depends sensitively on the solvent dielectric strength, and that for low dielectric solvents, barriers are dictated by diffusion of ion pairs rather than single ions.

The acidolysis of epoxides is an important series reaction applied in the polymer industry including coating and rubber. Glycidyl neodecanoate, which is a green material of environmentally friendly coatings, is synthesized through the acidolysis reaction of epichlorohydrin (ECH) with neodecanoic acid. We developed a green catalyst named tetramethylammonium neodecanoate (TMAN) for this reaction. TMAN is totally recyclable and the reaction system can be homogeneous, thus combining the advantages of tertiary amines and quaternary ammonium salts, meanwhile eliminating their drawbacks. Comparing with tetramethylammonium chloride (TMAC) which is a traditional industrial catalyst, the amount of side product dichlorohydrin can be reduced by more than 50%, effective utilization of ECH and yield of the main product can be increased by 5% and 2% respectively, and the reaction time can be reduced by 20% or more. We suggested a main catalytic reaction network including the conversion of TMAN to TMAC at the late stage of the reaction, and TMAC can be easily recycled and reused to prepare TMAN. More importantly, after the replacement of material acid and the carboxylic anion of catalyst, this efficient catalytic system and the mechanism network can be applied to other acidolysis reactions of epoxides.

In this paper the objectives were not only to investigate new promising methods leading to a deep structural rearrangement of carboranes and metallacarboranes but also to try to fix, to isolate and to characterize the intermediates. At the same time considerable attention is paid to the so-called "anti-wade" clusters formed during the reactions, the electronic structure of which does not correspond to their actually observed geometry. It is shown that the interaction of 11-vertex monocarbon closo-carboundecaborane with tris(triphenylphosphine)ruthenium dichloride leads to a series of new metallacarborane complexes. For the first time it was possible to control the process of "polyhedral contraction" of carborane {CB10} → (RuCB10} → {RuCB9} → {RuCB8} → {RuCB6} on the example of ruthenium complex and also to confirm experimentally each stage of the whole process. As a result of the reaction clusters of classical type and electron-deficient isocloso-/hypercloso-rutenacarborans {RuCB8}, {RuCB9} with 2n skeletal electrons were isolated. It is found that the interaction of tetramethylammonium closo-carboundecaborate with tris(triphenylphosphine)ruthenium dichloride proceeds in several stages. The first intermediate 12-vertex cluster is formed by mixing the initial reagents under heterogeneous conditions (methanol-THF, K2CO3, triethylbenzylammonium chloride) at room temperature for 10 hours. When the resulting complex is stirred in a mixture of methanol-THF solvents for 7 days at 20 °C, its almost quantitative transition to 11-vertex rutenacarborane was observed. Further transformation with the formation of a 10-vertex isocloso-rutenacarborane occurs when the methanol solution of this complex is boiled for 15 minutes. When the complex is boiled in methanol for 8 hours we obtained another extraordinary metallacarborane belonging to the rare 8-vertex pileo-clusters with a boron vertex built over the triangular face.

This work studied polyphenylene oxide tetramethylammonium (PPO-TMA) anion exchange membrane by dissipative particle dynamics (DPD) simulations. The simulation method is validated by semiquantitativ...

The interlayer condensation of layered silicates is a unique method for synthesizing zeolites and is effective for the introduction of metal species into platy zeolite frameworks. Layered silicate RUB-15 is a useful starting material because metal ions can be introduced between the layers and zeolite frameworks (all-silica SOD-type zeolite; silica sodalite) can be formed through interlayer condensation. In this study, Cu ions were intercalated into layered silicate RUB-15, and metal Cu nanoparticles were formed in the nanovoids of silica sodalite by a simple heat treatment in an inert atmosphere. Both interlayer condensation and the reduction of Cu2+ ions were confirmed by in situ XRD analysis performed during the heat treatment. The residual interlayer tetramethylammonium ions played two roles: the control of stacking sequence in the interlayer condensation and the reduction of Cu2+ ions. The formed Cu nanoparticles were stable in air atmosphere because of their confinement in the nanovoids of the sodalite frameworks.

Ionic plastic crystals are part of an emerging class of hybrid organic–inorganic ferroelectrics. The combination of low dielectric constants ( 100 pC N−1) and low temperature synthesis make ferroelectric plastic crystals strong candidates for sensing and energy harvesting applications so more research of the electrical properties, such as dielectric loss and super-coercive hysteresis is needed. Tetramethylammonium bromotrichloroferrate(III) was studied as a prototypical material and a non-centrosymmetric orthorhombic Amm2 structure was confirmed by X-ray diffraction at room temperature. The relative permittivity was below 20 at high frequencies (105 Hz) but high dielectric losses at frequencies 80 to 30 kV cm−1 and 0.046 to 0.017% respectively between 100 and 0.1 Hz. At 100 Hz the material exhibited a strong asymmetric hysteresis that was reversible depending on the electric field direction. The observed behavior was consistent with a defect pinning model of ferroelectric switching behavior and thus some likely point defect species were proposed and thought to result from solution non-stoichiometry or residual moisture and solvent.

As Bronsted acid sites in different types of channels exhibit distinct catalytic behaviors in the dimethyl ether (DME) carbonylation reaction over acidic mordenite (H-MOR) zeolites (e.g. acid sites in 8-membered ring channels for carbonylation reaction, acid sites in 12-membered ring channels for methanol-to-hydrocarbons reactions), the identification and regulation of acid site distribution in mordenite zeolites are of great importance to improve the catalytic performance. In this work, we employ the selective ion-exchange method to identify and control the acid site distribution in mordenite zeolites, and the chemical properties of acid sites in different channels are investigated by NH3-TPD and CD3CN FT-IR. Additionally, the effect of selective ion-exchange on the catalytic performance of DME carbonylation reaction is also discussed. The selective ion-exchange is realized by using tetramethylammonium (TMA+) ions, which can selectively remove the counter ions in the 12-membered ring channels but are inaccessible to the counter ions in 8-membered ring channels due to the steric hindrance. The selective ion-exchange reveals that the relative amounts of acid sites in 12-membered ring channels and 8-membered ring channels are 68% and 32%, respectively. Interestingly, it is found that introducing TMA+ into H-MOR zeolites significantly improves the catalytic activity and stability in DME carbonylation reaction as a result of depressing the methanol-to-hydrocarbons reactions. The 3TMA-H-MOR catalyst shows high stability for 210 hours on stream. The present work opens a new avenue for designing carbonylation catalysts with excellent stability in DME carbonylation reaction.

Tetrabutylammonium ions (TBA+) have commonly been used to exfoliate RuO2 into monolayers via ion exchange reactions. However, the low production yield of RuO2 exfoliation, which originates from the large molecular size of TBA+, limits wider utilisation of RuO2 monolayers in optoelectronic applications. We introduce a rapid and efficient dual-step exfoliation process beginning with intercalation of small organic molecules (tetramethylammonium ions) into RuO2, which is followed by the addition of TBA+ as a second intercalant to realize RuO2 monolayer production. Our dual-step intercalation process increases the RuO2 monolayer exfoliation yield from 9.9% to 60% after 14 days. Density functional theory calculations reveal that the activation energy of dual-step intercalation is much lower than that of direct intercalation of TBA+ ions into the RuO2 structure. The experimental and theoretical results of dual-step intercalation suggest that it is a facile and general approach for the production of metal oxide monolayers, and could widen the use of metal oxide monolayer nanosheets.

Reaction of SeO2 , tetramethylammonium (TMA) chloride, aqueous HCl and Cl2 yields oxochloroselenate with incorporated Cl2 units, TMA3 {[Se2 O2 Cl7 ](Cl2 )}. The main feature of this compound is the strong (up to 3.5 kcal mol-1 , according to DFT calculations) Cl⋅⋅⋅Cl bonding, which is also detected by Raman spectroscopy.

Niobium oxide thin films have been prepared by spin-coating aqueous solutions of tetramethylammonium salts of the isostructural polyoxometalate clusters [Nb10O28]6−, [TiNb9O28]7− and [Ti2Nb8O28]8− onto silicon wafers, and annealing them. The [Nb10O28]6− cluster yields films of Nb2O5 in the orthorhombic and monoclinic crystal phases when annealed at 800 °C and 1000 °C, respectively, whereas the [TiNb9O28]7− and [Ti2Nb8O28]8− clusters yield the monoclinic crystal phases of Ti2Nb12O29 and TiNb2O7 (titanium–niobium oxides) in different ratios. We also demonstrate a protocol for depositing successive layers of metal oxide films. Finally, we explore factors affecting the roughness of the films.

Racemic and enantiopure nickel(II) bis(dithiolene) anionic and neutral complexes based on the methyl-5,6-dihydro-1,4-dithiin-2,3-dithiolate (me-dddt) and dimethyl-5,6-dihydro-1,4-dithiin-2,3-dithiolate (dm-dddt) ligands have been experimentally and theoretically investigated with a special focus on their chiroptical properties. According to the time-dependent density-functional theory (TD-DFT) calculations, the strong near-infrared absorption bands typical for such complexes are only weakly active in circular dichroism (CD), and moreover, they have opposite signs for the axial and equatorial conformations, due to the variation of the angle between the transition electric and magnetic dipole moments, thus leading to the mutual cancellation of their contributions and the absence of these bands in the experimental CD spectra. The influence of the number of stereogenic centers and of the oxidation state of the complexes on their chiroptical properties is highlighted. The solid-state structure of the complex (TMA)[Ni(rac-me-dddt)2 ] (TMA = tetramethylammonium), determined by single-crystal X-ray diffraction analysis, shows a rather unusual cis arrangement of the two dithiolene ligands, with the methyl substituents adopting an axial conformation, which is not the most stable one in the gas phase.

Recent years have seen many specific applications of polyhalide ionic liquids (ILs) such as oxidizing solvents for metals and alloys, immersion fluids for optical mineralogy, and electrolyte components for dye-sensitized solar cells. In this work, interhalogen interactions in a set of polyhalide ILs composed of polyhalide anions, [X3]−, [X5]− and [X7]− (X = I or Br), with two typical cations, tetramethylammonium [NMe4]+ and 1,3-dimethylimidazolium [DMIM]+, were thoroughly studied from a computational point of view. In addition, a halogen-bonded supramolecular anion, [C6F13-I∙∙∙I∙∙∙I-C6F13]−, was also taken into account for comparison. Unlike those in bare polyhalide ions, halogen-halogen interactions in ionic pairs for the investigated ILs are somewhat asymmetric caused by the interactions between the cations and the anions. Most interhalogen contacts in ionic pairs have some covalent content, while I∙∙∙I interactions in the complexes of the supramolecular anion are purely noncovalent. In general, there are two classes of interhalogen bonds in ionic pairs: one class with longer X∙∙∙X distances shows primarily ionic character, while the other with shorter distances has a larger degree of covalency, i.e. intermediate ionic/covalent nature.

Unlike polyhalides of heavier halogens, polychlorides still remain exotic curiosities. Herein, we report preparation and investigation of complexes Cat2 {[TeCl6 ](Cl2 )} (cat=1-methylpyridinium (1) and tetramethylammonium (2)) where dichlorine units are "trapped" by chlorotellurate(IV) anions via a system of non-covalent Cl⋅⋅⋅Cl interactions. Complex 2 reveals a record thermal stability (>100 °C) for inclusion compounds with Cl2 , indications that such compounds can be used as solid Cl2 source.