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As important building blocks in natural products and organic synthesis, thioethers have a wide range of potential applications. Herein, polyoxometalate-based ionic liquids (POM-ILs-SO3H) derived from N-alkyl imidazole were synthesized and used for the first time for the thiolation of alcohols to construct C–S bonds in a series of benzyl thioethers. This type of POM-ILs-SO3H catalyst exhibited high catalytic activity, providing up to 98% yield of thioether within 1 h at 70 °C. The alkyl chain length of the imidazole had a certain effect on the solubility of the POM-ILs-SO3H catalysts in the reaction solvent, and then affected their catalytic activity. The catalytic system had a wide substrate scope and was suitable for the reaction of tertiary and secondary benzyl alcohols with thiophenols or cycloalkyl thiols. In particular, [PIMPS]3PW12O40 (PIM = 1-propylimidazole, PS = propane sulfonate) as a reversible phase transformation-type catalyst, combining the advantages of homogeneous and heterogeneous catalysts, exhibited high activity and good recyclability with only a slight decrease in the yield after five runs. Additionally, a carbocation mechanism was proposed for the thiolation reaction of alcohols. [ABSTRACT FROM AUTHOR]

In this paper, we have demonstrated the facile synthesis of stable gold nanoparticles (AuNPs) using imidazolium ionic liquids (ImILs) as a stabilizer as well as a surfactant and their surface plasmon resonance (SPR) in different molecular solvents with varying dielectric properties. The preparation of AuNPs capped with N,N′-dialkyl ImILs of different chain lengths (denoted as [C4,Cn-im]Br, n = carbon number of the alkyl chain) has been investigated. With one long alkyl chain (n≥ 14), these AuNPs could be stably dispersed in solution over a month. The amphiphilic nature of the imidazolium salt dictates the stability and dispersion of these AuNPs in organic or aqueous solvents. Alkyl chain lengths (n≥ 14) and the amount of ImILs have insignificant effect on the size of AuNPs and they possess an average size of 5 nm. These ionic liquid stabilized AuNPs were exploited to examine their optical properties when exposed to various solvent systems by measuring the change in the SPR spectrum. It was seen that the position of the SPR band of AuNPs is greatly influenced by the solvents under consideration. The shift in the SPR absorption band is observed to be in the range of 520 nm to 605 nm for AuNP@[C4,C16-im]Br from nonpolar to highly polar solvents. The considerable discovery presented here is that the λSPR of the SPR shifts to the blue with the increase of carbon atom in the alcohol chain from methanol to 1-decanol. Also for polyethylene glycols (PEGs), the λSPR shifts to the blue with the increase in molecular weight from PEG 200 to PEG 600. In above both cases, the variation in SPR of AuNPs is observed according to the dielectric properties of the medium in addition to the steric factor of alcohols and PEGs during their interaction with AuNP surfaces. [ABSTRACT FROM AUTHOR]

The simultaneous achievement of large surface areas and high IL contents in porous materials are highly beneficial for efficient carbon dioxide (CO2) capture and atmospheric fixation. Herein, a series of porous hypercrosslinked poly(ionic liquid)s (HPILs) are successfully developed through a two-step synthetic strategy, including free radical self-polymerization of a specific benzyl bromide-tethered imidazole ionic liquid (IL) to fabricate a linear PIL as a precursor, and a subsequent Friedel–Crafts alkylation between the precursor and the crosslinker for hypercrosslinking. The HPILs featured large surface areas of up to 855 m2 g−1 along with a hierarchically nanoporous structure, high IL contents (2.19–2.91 mmol g−1) and satisfactory CO2-philic properties. By virtue of the combined advantages, HPILs served as metal-free heterogeneous catalysts for solvent-additive-free CO2 cycloaddition with epichlorohydrin at 80 °C and 0.1 MPa CO2 for 24 h, presenting high catalytic activity and stable reusability. A high yield of 99.0% coupled with a turnover frequency (TOF) of 6.0 h−1 was achieved, much higher than most of the reported metal-free heterogeneous catalysts, even superior to homogeneous analogues. Furthermore, various epoxides, including large-sized epoxides, were effectively converted into carbonates with high yields, affording good substrate applicability. This work reports a facile and universal approach for the construction of porous HPILs with both great porosities and high IL contents towards efficient chemical fixation of CO2 under mild conditions. [ABSTRACT FROM AUTHOR]

It is necessary to recover precious metals from aqueous solutions because they have a wide range of applications. In this work, a poly(ionic liquid) (PIL) gel containing an imidazole group was fabricated using a radiation method and utilized for the capture of Au(III), Pt(IV), and Pd(II) ions. It was discovered that the PIL gel exhibited high adsorption efficiency for Au(III), Pt(IV), and Pd(II) in a wide pH range. The adsorption processes for target ions all reached equilibrium within 4 min. Meanwhile, the isotherm experiments revealed that the adsorption was in accordance with the Langmuir model, and the maximum adsorption capacities were 854.7 mg g−1 for Au(III), 420.2 mg g−1 for Pt(IV), and 277.8 mg g−1 for Pd(II). Furthermore, the PIL gel could selectively adsorb Au(III), Pt(IV), and Pd(II) from simulated acidic waste effluent containing Cu(II), Zn(II), Fe(III), and Ni(II). In particular, the PIL gel demonstrated its ability to selectively recover trace Au(III) from real gold slag leaching solution. FTIR and XPS analyses revealed that anion exchange was the dominant adsorption mechanism. [ABSTRACT FROM AUTHOR]

By adding different proportions of N-butylimidazole and carboxyethylthiosuccinic acid (CETSA), three hybrid systems of ionic liquids were synthesized and named ILHS1, ILHS2 and ILHS3. Using the weight loss method, electrochemical impedance spectroscopy (EIS), scanning electron microscopy (SEM) and contact angle test, it was determined that ILHS2 had the best corrosion inhibition among the three ionic liquid systems, and that the inhibition efficiency reached up to 90.63% when the concentration was 10 mM in 1 M HCl at 308 K. The adsorption isotherm was consistent with Langmuir adsorption, and combined with molecular dynamics simulation (MD), it was proved that mixed adsorption occurred on the metal interface. Polarization curves showed that the ionic liquid mixture systems could inhibit the corrosion of both poles, meaning that the anions and cations could act synergistically, and that the anions played a major role. The elemental and molecular structures of ILHS1, ILHS2 and ILHS3 were investigated using 1H NMR, which indicated that the three carboxyl groups on CETSA were regionally selective and combined with imidazole cations to form ionic liquid mixture systems. [ABSTRACT FROM AUTHOR]

Bismuth SBA-16 catalyst was synthesized by the hydrothermal method. Four kinds of p-toluenesulfonic acid functionalized imidazole ionic liquids were prepared by a two-step method and their molecular structures were characterized by 1H NMR and MS. The post-synthesis impregnation method was used to functionalize the Bi(10)-SBA-16 silicon mesoporous material with the ionic liquids and the obtained materials were characterized by FT-IR, XRD, BET, XPS, and TG. The results show that the volume and pore size of SBA-16 were changed by loading Bi and ionic liquids, while the three-dimensional cubic pore structure of SBA-16 was not destroyed. The composite catalyst was evaluated in Friedel–Crafts acylation of anisole with acetic anhydride. The effects of reaction temperature and the ratio of anisole and acylating agent on the acylation of anisole were investigated by experimental design. The results showed that 1.2ILc@Bi(10)-SBA-16 was used as the catalyst, the conversion of anisole was 85.41% and the yield of aromatic ketone was 69.19% under the conditions of a reaction temperature of 100 °C, a catalyst dosage of 0.5 g, a time period of 4 h and a molar ratio of 1 : 1.5. After 5 recycling runs, the reduction in the overall ratio of reactant conversion and product yield did not exceed 7.5%, indicating that 1.2ILc@Bi(10)-SBA-16 has good stability and reusability. [ABSTRACT FROM AUTHOR]

Ionic liquids (ILs) are receiving growing interest as highly tunable, multifunctional materials. Remarkably for liquids, they tend to display a high level of structural order. This structural order may even lead to the formation of mesophases such as liquid crystals (LCs). Imidazolium compounds are by far the most popular ILs, because they offer a widely versatile platform for property tuning. To investigate what is driving structural order in imidazolium-based ILs a series of asymmetrical 1-dodecyl-2-methyl-3-alkylimidazolium bromides, [C12C1Cnim][Br] with n = 0–12 have been synthesized, fully characterized and their structures and properties compared with the analogous 1-dodecyl-3-alkylimidazolium as well as the 1,2,3-triazolium bromides. The aim is to examine the influence of the replacement of the most acidic 2-H proton on the imidazolium head group by methylation on the properties and structure of ILs. For all compounds, except for compounds with butyl- and hexyl-chains as well as the protonated species, mesophase formation can be observed. Obviously, the simple presence of long alkyl chains such as dodecyl (a design concept frequently put forward in the literature) is not sufficient to support mesophase formation alone. Rather, for the formation of a liquid crystalline phase, a balance between attractive van der Waals forces, hydrogen bonds, and electrostatic interactions is required. Data from temperature-dependent small-angle X-ray scattering (SAXS) and polarizing optical microscopy (POM) suggest three different cation conformations for the studied [C12C1Cnim][Br]: cations with 0 ≤ n ≤ 4 exhibit a near-linear conformation; for 5 ≤ n ≤ 10 a V-shape is adopted, and for n = 11 or 12 a U-shape is found. We demonstrated that the structural possibility for an interdigitation of the long chains is an influential factor for the formation of a mesophase. [ABSTRACT FROM AUTHOR]

Alcoholysis is a potential method for the degradation of polyesters to their precursor building blocks, which can then be polymerized again to form new qualified polyester materials. This method therefore makes recycling possible in a permanent polymer–monomer–polymer loop. In this study, a series of metal-free tetrabutylphosphonium-based ionic liquids (ILs) were prepared as catalysts for the methanolysis of poly(ethylene 2,5-furandicarboxylate) (PEF), which is well known as an ideal alternative to the petroleum-based plastic poly(ethylene terephthalate) (PET). It was found that anions with stronger electronegativity were more efficient for the methanolysis of PEF. By adjusting the structures of the anions and cations of ILs, 1-butyl-3-methylimidazole acetate ([BMIm][OAc]) exhibited excellent catalytic activity in the methanolysis of PEF. The optimization of reaction parameters enabled the [BMIm][OAc]-catalyzed methanolysis of PEF with nearly 100% PEF degradation and a 77.6% dimethyl furan-2,5-dicarboxylate (DMFD) yield at 130 °C for 30 min. Furthermore, [BMIm][OAc] could keep high-activity after using for six times under the optimum conditions. Assisting with 1H NMR, FT-IR and density functional theory (DFT) calculations, an in-depth study was performed on the feasible synergetic catalytic mechanism of [BMIm][OAc] for the methanolysis of PEF, induced by hydrogen bonds formed between reactants and [BMIm][OAc]. Finally, on the basis of experimental results and scanning electron microscopy (SEM), it was confirmed that PEF with the spiral motif could be degraded under milder conditions than PET. Therefore, this strategy of using adjustable cation and anion structures in ILs provides an opportunity to develop other more efficient ILs for the alcoholysis of furan-based polymers via a green and mild pathway. [ABSTRACT FROM AUTHOR]

In this study, a series of high-activity imidazole-based dicationic ionic liquids (DILs) were designed and prepared as efficient catalysts for balancing the reactivity between the endo-hydroxyl group (endo-OH) and the exo-hydroxyl group (exo-OH) of isosorbide (ISO) to synthesize high molecular weight poly(isosorbide carbonate) (PIC). Meanwhile, the thermal performance of PIC was precisely optimized by regulating the chain configuration. The results showed that when the trace amounts (4.5 × 10−5 based on the ISO molar amount) of bis-(3-methyl-1-imidazole)-ethylene dibromide ([C2(Min)2][Br]2) were used, the weight average molecular weight (Mw) of PIC reached 98 700 g mol−1. It could be concluded from the results of the experiment and the stimulation that the high catalytic activity of DILs was attributed to the strong electrostatic interaction between the cation and the substrate and the effective balance of the reactivity of the endo-OH and the exo-OH. Furthermore, we found that the reduction of hydroxyl groups in the terminal groups and the increase of endo–endo (a1) structure in the repeating unit improved the thermal properties of PIC. Finally, 1H NMR, Fourier infrared spectroscopy, and density functional theory (DFT) calculations were used to verify the reaction process through anion and cation multi-site synergistic effect and a possible electrophilic–nucleophilic reaction mechanism was successfully obtained. [ABSTRACT FROM AUTHOR]

The synthesis of a novel poly(ionic liquid) adsorbent (PIL-APIBCl) through the modification of poly(styrene-co-maleic anhydride) (PSMA) composites with N-(3-aminopropyl)imidazole (API) and benzyl chloride (BCl) is presented. The structural analysis was carried out by nuclear magnetic resonance (NMR), X-ray photoelectron spectroscopy (XPS), field emission scanning electron microscopy (FESEM) and Fourier transform infrared (FT-IR). Batch adsorption experiments revealed that the investigated adsorbent exhibited good selectivity and a high adsorption capacity of 236.68 mg g−1 towards tetrachloroaurate (Au(III)) ions at pH 1.0 over a wide temperature range. The adsorption isotherms and kinetics of Au(III) on the PIL-APIBCl were fitted well by the Langmuir isotherm model and pseudo-second-order model, respectively, indicating successful chemical adsorption of Au(III) ions on the adsorbent surfaces. According to FESEM, FT-IR, XPS and NMR analysis, the adsorption mechanisms of Au(III) on PIL-APIBCl could be ascribed to electrostatic and intermolecular interactions. Therefore, due to its good cyclability and low cost, PIL-APIBCl is a promising adsorbent for Au(III) recovery from wastewater on a large scale. [ABSTRACT FROM AUTHOR]

The immobilization of two titanocene complexes on SBA-15 has been accomplished following post-synthetic procedures. The ionic liquid, 1-methyl-3-[(triethoxysilyl)propyl]imidazolium chloride, has also been incorporated into the titanium containing materials to determine its influence on the interaction with molecules of biological interest. Cyclic voltammetry has been used to study the influence of the ionic liquid on the mechanism of reduction of titanocene derivatives. The interaction of titanocene and titanocene/ionic liquid-containing mesoporous silica SBA-15 materials, with molecules of biological interest associated with important processes of metallodrug action against cancer cells, has been studied. Thus, we have carried out hydrolysis experiments on the materials functionalized with titanocene derivatives in physiological media to determine their stability and the interaction with serum/transport proteins such as transferrin and BSA and with target molecules such as guanosine, single-stranded DNA and double-stranded DNA by means of solid state voltammetry techniques. A qualitative analysis of the data based on peak current and reduction potential value changes of the couple Ti(iv)/Ti(iii) in the presence of biomolecules at physiological pH, has revealed that grafted titanocene complexes show higher affinity for serum/transport proteins than for nucleic acids, indicating that the transport steps to the cells may be easier than the subsequent attack on DNA. [ABSTRACT FROM AUTHOR]

The separation of aromatics from aliphatics is challenging and energy-consuming because of the very close boiling points among these compounds and the possibility of forming azeotropes. In this work, we designed two imidazolium-based dicationic ionic liquids, [C5(MIM)2][NTf2]2 (DIL1) and [C6(MIM)2][NTf2]2 (DIL2), and found that they could highly efficiently extract aromatics from aliphatics. Three different aromatic and aliphatic mixtures, toluene/n-heptane, benzene/n-hexane and benzene/cyclohexane, were used to investigate the universality of DILs. The extractive performance of both DILs was compared with those of other promising ILs and sulfolane. The mixtures of toluene and aliphatics with different chain lengths were also investigated. The results showed that the two DILs had relatively high selectivity and distribution coefficients for different aromatic and aliphatic mixtures. At 30 °C, the highest values of selectivity and distribution coefficient for toluene/n-heptane, benzene/n-hexane and benzene/cyclohexane systems were 50.4, 64.8, and 24.9 and 1.44, 2.44, and 2.25, respectively. The performance of DILs at 30 °C was better than that at 40 °C. Besides, a higher selectivity could be obtained when toluene is used with a longer chain aliphatic, such as a selectivity of 61.4 could be obtained when the aliphatic was n-nonane. The study of the physicochemical properties of DILs showed that they were more stable than the previous ones. In a word, the two DILs were evaluated as potential solvents for the separation of aromatics from aliphatics. [ABSTRACT FROM AUTHOR]

We present an efficient Ullmann-type synthesis methodology enabling the preparation of imidazolium compounds with an extended aromatic core in three steps. This procedure begins with a microwave-assisted, heterogeneously catalysed cross-coupling reaction in the presence of Cu(ii)-doped NaY zeolite to obtain imidazole-aromatic derivatives directly in good yield. The innovation is that this reaction does not require solvent, ligand or an inert atmosphere. Subsequently, these derivatives have been alkylated with bromoalkanes and the bromide of the imidazolium products exchanged for [BF4]− or [PF6]− anions. We have studied the influence of the methyl group (inductive effect) on the aromatic unit during the coupling reaction as well as its impact on different arrangements in the crystalline state. We have been able to extend this synthesis to ionic liquid crystal compounds which display lamellar self-organization (smectic A). The mesomorphic behavior and phase transition temperatures were investigated by polarizing optical microscopy (POM), differential scanning calorimetry (DSC) and small-angle X-ray scattering (SAXS). [ABSTRACT FROM AUTHOR]

In this article, the preparation of bis-imidazolium hydrogen sulfate and bis-imidazolium perchlorate as two new bis-dicationic Brönsted acidic ionic liquids based on imidazole is reported. After characterization by FT-IR, mass and NMR spectroscopy and pH titration, the applicability of these reagents is studied in the promotion of the synthesis of 5-arylidene barbituric acids and pyrano[2,3-d] pyrimidinone derivatives. These methods possess some advantages such as ease of preparation of the catalyst, simple work-up procedure, short reaction times, excellent yields, and use of nonorganic solvents during all steps of the reactions and good reusability of the catalysts. [ABSTRACT FROM AUTHOR]

In the present study, heterogenization of amine-functionalized ionic liquids was developed via covalent immobilization of 2-chloroethylamine on imidazole modified graphene oxide (GO) sheets. The prepared material was characterized by various physicochemical techniques such as Fourier transform infrared spectroscopy (FT-IR), powder X-ray diffraction (XRD), thermogravimetric analysis (TGA), transmission electron microscopy (TEM), scanning electron microscopy (SEM) and energy-dispersive X-ray (EDX) spectroscopy. The prepared material was employed as an efficient heterogeneous catalyst for the synthesis of 3-substituted indoles via Yonemitsu-type reaction. The catalyst could be easily separated from the reaction mixture through centrifugation and could be reused for seven consecutive cycles without any appreciable loss in its catalytic activity. [ABSTRACT FROM AUTHOR]

A new, versatile, and green route to access ionic liquids containing carbonate groups, including 1-[2-(propyloxycarbonyloxy)ethyl]-3-methyl imidazolium and N-methyl-N-[2-(propyl-oxcarbonyl) ethyl] pyrrolidinium associated with a bis(trifluoromethane)sulfonimide anion, [C1(C2O(CO)OC3)Im][NTf2] (4) and [C1(C2O(CO)OC3)Py][NTf2] (5), has been developed and characterized. The key point of this route is to avoid the metathesis reaction step with LiNTf2, which could result in ionic liquids that are highly contaminated with LiCl salt through the coordination of lithium ions by the carbonate group. [ABSTRACT FROM AUTHOR]

Fluoroquinolones (FQs) and Non-Steroidal Anti-Inflammatory Drugs (NSAIDs) are two classes of Active Pharmaceutical Ingredients (APIs) in widespread use in human healthcare and as veterinary drugs, and that have been found throughout the water cycle in the past years. These two classes of APIs are commonly present in aqueous streams in concentrations ranging from ng L−1 to μg L−1. Despite such low concentrations, these contaminants tend to bioaccumulate, leading to serious environmental and health issues after chronic exposure. The low concentrations of FQs and NSAIDs in aqueous media also render difficult identification and quantification, which may result in an inefficient evaluation of their environmental impact and persistence. Therefore, the development of alternative pre-treatment techniques for their extraction and preconcentration from aqueous samples is a crucial requirement. In this work, liquid–liquid systems, namely ionic-liquid-based aqueous biphasic systems (IL-based ABS), were tested as simultaneous extraction and preconcentration platforms for FQs and NSAIDs. ABS composed of imidazolium-, ammonium- and phosphonium-based ILs and a citrate-based salt (C6H5K3O7) were evaluated for the single-step extraction and enrichment of three FQs (ciprofloxacin, enrofloxacin and norfloxacin) and three NSAIDs (diclofenac, naproxen and ketoprofen) from aqueous samples. Outstanding one-step extraction efficiencies of APIs close to 100% were obtained. Furthermore, the preconcentration factors of both FQs and NSAIDs were optimized by an appropriate manipulation of the phase-forming components compositions to tailor the volumes of the coexisting phases. Preconcentration factors of 1000-fold of both FQS and NSAIDs were obtained in a single-step process, without reaching the saturation of the IL-rich phase. The preconcentration of APIs up to mg L−1 allowed their easy and straightforward identification and quantification by a High-Performance Liquid Chromatography (HPLC) system coupled to an UV detector, as shown for both model systems (distilled water) and real effluent samples from a wastewater treatment plant. [ABSTRACT FROM AUTHOR]

An imidazolium based ionic liquid, 1-methyl-3-(3-triethoxysilylpropyl) imidazolium chloride, could be immobilized on the surface of silica-coated ferrite nanoparticles (Fe3O4@SiO2-IL) and could be evaluated as a recyclable catalyst for the N-formylation of amines using formic acid under solvent-free conditions. The prepared organic–inorganic hybrid material could be characterized by various techniques such as Fourier Transform Infrared Spectroscopy (FT-IR), X-Ray Diffraction (XRD), Transmission Electron Microscopy (TEM), Scanning Electron Microscopy (SEM), Energy Dispersive X-Ray Spectroscopy (EDS) and Vibrating Sample Magnetometer (VSM) studies. Utilizing the ferromagnetic nature of Fe3O4, the prepared catalyst could be easily recovered after completion of the reaction by using an external magnetic field. The catalyst could be reused for up to five runs with remarkable catalytic activity. The described methodology has various advantages when compared with other methods that rely on homogeneous catalysts. [ABSTRACT FROM AUTHOR]

In this study, two biological template molecules and two common short-chain imidazolium ionic liquids with amphipathy were selected to synthesize four different types of metal nanoclusters (MNCs), which were templated on a biological molecule/imidazolium ionic liquids (ILs) complex with properties enhancement. The fluorescence intensity and stability of the MNCs were improved in different degrees via this simple and fast protocol. The fluorescence intensity of AgNCs was significantly enhanced primarily due to aggregation-induced emission (AIE), and it was attributed to the shrinking size and donation of delocalized electrons for other MNCs. Different template molecule must match with appropriate ILs to form a steady complex that stabilizes the MNCs. The stability of the MNCs was improved, especially for AuNCs, because biological molecule/imidazolium ILs complex was found to be an effective barrier in protecting the MNCs from quenching interactions. Compared to conventional cationic surfactant (sodium dodecyl sulfate, SDS), these imidazolium ILs exhibited superior properties enhancement of the nanomaterials. MNCs with excellent properties could be applied in bioanalysis, especially in fluorescence imaging in vitro, because of their undisturbed and durable optical signal. [ABSTRACT FROM AUTHOR]

Eight imidazolium-based salts with the weakly-coordinating anions [BArF]− and [Al(OtC4F9)4]− ([BArF]− = tetrakis{3,5-bis(trifluoromethyl)phenyl}borate) have been synthesized. Characterization by 1H NMR spectroscopy shows that the salts are fully dissociated in solution. Six examples have been further characterized by X-ray crystallography, revealing that weak hydrogen bonds do occur in the solid phase between the imidazolium cations and weakly coordinating anions. Comparison with the bulky [IDiPPH] imidazolium cation (IDiPPH = 1,3-bis{2,6-bis(diisopropyl)phenyl}imidazolium) shows that large steric bulk close to the imidazolium protons can preclude hydrogen bonds from forming. Differential scanning calorimetry of the salts reveal that all are thermally stable up to 200 °C which renders them as potentially suitable background electrolytes for electrochemical processes which take place at elevated temperatures. [ABSTRACT FROM AUTHOR]

A facile aromatic nucleophilic substitution (SNAr) reaction in recyclable [Omim]Br under relatively mild conditions has been described. An electrophile–nucleophile dual activation by [Omim]Br is also discovered based on control experiments, 1H NMR and IR spectroscopies. This chemistry provides an efficient and metal-free approach for the generation of Caryl–X (X=S, N, O) bonds, many of which are significant synthetic intermediates or drugs, making this methodology attractive to both synthetic and medicinal chemistry. [ABSTRACT FROM AUTHOR]

Sixteen new ionic liquids (ILs) with tetraethylammonium, 1-butyl-3-methylimidazolium, 3-methyl-1-octylimidazolium and tetrabutylphosphonium cations paired with 2-substituted 4,5-dicyanoimidazolate anions (substituent at C2 = methyl, trifluoromethyl, pentafluoroethyl, N,N′-dimethyl amino and nitro) have been synthesized and characterized by using differential scanning calorimetry (DSC), thermogravimetric analysis (TGA). The effects of cation and anion type and structure of the resulting ILs, including several room temperature ionic liquids (RTILs), are reflected in the crystallization, melting points and thermal decomposition of the ILs. ILs exhibited large liquid and crystallization ranges and formed glasses on cooling with glass transition temperatures in the range of −22 to −71 °C. We selected one of the newly designed ILs due to its bigger size, compared to the common conventional IL anion and high electron-withdrawing nitrile group leads to an overall stabilization anion that may stabilize the metal nanoparticles. Stable and better separated iron and silver nanoparticles are obtained by the decomposition of corresponding Fe2(CO)9 and AgPF6, respectively, under N2-atmosphere in newly designed nitrile functionalized 4,5-dicyanoimidazolate anion based IL. Very small and uniform size for Fe-nanoparticles of about 1.8 ± 0.6 nm were achieved without any additional stabilizers or capping molecules. Comparatively bigger size of Ag-nanoparticles was obtained through the reduction of AgPF6 by hydrogen gas. Additionally, the AgPF6 precursor was decomposed under microwave irradiation (MWI), fabricating nut-in-shell-like, that is, core-separated-from-shell Ag-nano-structures. [ABSTRACT FROM AUTHOR]

A series of temperature-dependent gel-type ionic liquid compounds have been synthesized from 1-(3-sulfonic group) propyl-3-methyl imidazolium (abbreviated as MIMPS) and three vanadium-substituted heteropoly acids H5SiW11VO40, H5SiMo11VO40 and H7SiW9V3O40. The designed and synthesized gel-type polyoxometalate ionic liquids (POM-ILs) have demonstrated a tendency to exhibit a layered structure. Moreover, they can undergo a phase transformation from a viscous gel-state to a liquid-state below 100 °C, and ionic conductivity up to 10−3 S cm−1 was observed at 120 °C. Cyclic voltammetry was carried out to study their electrochemical properties in organic solutions, and it was found that the oxidizability of the three POM-ILs decreases in the order: [MIMPS]7SiW9V3O40 ＞ [MIMPS]5SiMo11VO40 ＞ [MIMPS]5SiW11VO40. This result indicates that the redox behavior can be tuned by changing the chemical composition of the heteropolyanions. [ABSTRACT FROM AUTHOR]

Vitamin E (VE) has significant biological activities and thus its acylation to increase its stability is of extreme interest. We developed an efficient and sustainable approach using imidazolium-based ionic liquids as dual solvent-catalysts for the esterification between α-tocopherol (the most active form of VE) and succinic anhydride. Although in literature it is reported that lipase can catalyze this reaction, hereby we demonstrate that the reaction observed in DMSO and DMF is catalyzed by the histidyl residues of the protein. Histidine and its analogue containing an imidazole ring were tested as organocatalysts for the production of α-tocopherol succinate. In light of the imidazole organocatalysis, commercially-available 3-alkyl-1-methyl imidazolium ILs [CnC1Im][X−] were investigated as dual solvent-catalysts for the esterification of α-tocopherol with succinic anhydride, and provided satisfactory yields and reaction rates. [C5C1Im][NO3−] can be recycled by water extraction, instead of organic solvent extraction to separate α-tocopherol succinate from [C5C1Im][NO3−], with an average yield of 94.1% for 4 subsequent batches, while the catalytic activity of the recycled ILs showed almost no loss after 4 batches. The developed protocol for the synthesis of α-tocopherol esters and IL recycling bears industrial potential due to the ease of use and the efficient recycling. [ABSTRACT FROM AUTHOR]

Novel multi-SO3H functionalized strong Brønsted acidic ionic liquid coated magnetite nanoparticles have been prepared and applied as catalyst for the synthesis of 2,4,5-trisubstituted imidazoles. The results showed that a novel catalyst was very efficient for the reaction and could be magnetically separated and reused at least 6 times with less reduction in its catalytic activity. Operational simplicity, low cost of the catalyst used, high yields, environmental friendliness, wide applicability, reusability and easy recovery of the catalyst using an external magnet are the most important features of this methodology. The catalyst was characterized by Fourier transform infrared spectroscopy (FT-IR), X-Ray diffraction analysis (XRD), field emission scanning electron microscopy (FE-SEM), energy dispersive X-ray analysis (EDX), dynamic laser scattering (DLS) and vibrating sample magnetometry (VSM). [ABSTRACT FROM AUTHOR]

Coralloid Fe3O4 nanoclusters stacked by nanosheets are successfully synthesized using ferric nitrate as a precursor with an ionic liquid-assisted solvothermal method. For comparison, spherical Fe3O4 nanoclusters assembled by nanospheres are synthesized in the absence of ILs. The morphologies and structures of the products are further characterized by field emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), X-ray power diffraction (XRD), and X-ray photoelectron spectroscopy (XPS). The results indicate that the ionic liquid 1-n-decyl-3-methylimidazolium chloride ([Dmim]Cl) plays an important role in controlling the growth orientation of building blocks via selectively adsorbing on a specific crystal plane. A formation mechanism has been proposed based on the interaction between ILs and Fe3O4 crystal planes. The catalytic activity of nanoclusters has been evaluated with the Fenton reaction under UVA irradiation. The coralloid nanoclusters show the highest catalytic activity for the degradation of phenol due to their special morphology and unique surface properties. The synthesis strategy may provide a new way to construct nanomaterials with novel morphologies and excellent properties. [ABSTRACT FROM AUTHOR]

An investigation on a process designed for separating Pt(iv) and Pd(ii) dissolved in acidic aqueous solution containing HCl using two ionic liquids, 1-octyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ([OMIM][NTf2]) and trihexyltetradecylphosphonium bromide (Cyphos 102), is presented. To this end, the single extraction of platinum in [OMIM][NTf2] has been investigated as a function of the initial concentration of Pt(iv) ions dissolved in 1 M HCl. The distribution coefficient for Pt(iv), present in water as a PtCl62− anion, decreases with the concentration of Pt(iv). The extraction of Pd(ii) towards [OMIM][NTf2] or Cyphos 102 as a function of the concentration of HCl in the aqueous phase is also reported. Pd(ii), present as PdCl42− in water, is not extracted using [OMIM][NTf2]. On the other hand, the distribution coefficients of Pd(ii) using Cyphos 102 are above 2000. In this ionic liquid, Pd(ii) is extracted as a PdBr42− anion. Separation of Pt(iv) from Pd(ii) was then carried out starting from aqueous phases containing 1 M HCl and various initial concentrations of Pt(iv). The influence of the number of extraction steps using [OMIM][NTf2] on the extraction of Pt(iv) was also studied. Unlike the results obtained from single extraction experiments of Pt(iv), consecutive extraction of Pt(iv) in water using [OMIM][NTf2] does not improve significantly the extraction of this metal ion. The second step of the extraction process carried out using Cyphos 102 leads to the quantitative extraction of Pd(ii) and Pt(iv) remaining in the aqueous phase. [ABSTRACT FROM AUTHOR]

Two types of 2D [RMI]2[Zn3(BDC)3X2] (Type A) and 3D [Zn(BDC)(H2O)] (Type B) (H2BDC = 1,4-benzenedicarboxylate acid) compounds were synthesized with three kinds of 1-alkyl-3-methyl imidazolium halide ([RMI]X) ionic liquids. Type A is the primary structure model showing a (3,6) network. Type B can be obtained from [BMI]Cl, [AMI]Cl and [AMI]Br media, showing a 4,4-connected {42·84} network. The structure, TG, and fluorescence analyses demonstrate the combination effect of the RMI+ templating effect and X− controlling the structure types. The boundary between Types A and B is from [PMI]Cl, via [BMI]Br, to [AMI]I as the reaction media. The decomposition temperatures of the compounds in Type A decrease with increased RMI+, while X− anions exert the influence that compounds containing Br− supply the highest thermal stability. Similarly, with increased RMI+, or X = I−, the compounds show red shifts compared to the emissions of the ligand. [ABSTRACT FROM AUTHOR]

In the current study, a novel ionic liquid-based zwitterionic organic polymer monolithic column was developed by copolymerizing 1-vinyl-3-(butyl-4-sulfonate) imidazolium, acrylamide and N,N′-methylenebisacrylamide in a quaternary porogenic solvent consisting of formamide, dimethyl sulphoxide, polyethylene glycol 8000 and polyethylene glycol 10 000 for capillary hydrophilic interaction chromatography. The monolithic stationary phase was optimized by adjusting the amount of monomer in the polymerization solution along with the composition of porogenic solvent. The optimized monolith exhibited excellent selectivity and favorable retention for nucleosides and benzoic acid derivatives. The primary factors affecting the separation efficiency of the monolithic column (including acetonitrile content, pH, and buffer salt concentration in the mobile phase) have been thoroughly evaluated. Excellent reproducibility of the retention times for five nucleosides was achieved, with relative standard deviations of run-to-run (n = 3), column-to-column (n = 3) and batch-to-batch (n = 3) in the range of 0.18–0.48%, 2.33–4.20% and 3.07–6.50%, respectively. [ABSTRACT FROM AUTHOR]

Well-distributed Ru nanoparticles (Ru-NPs) were produced over Al2O3 supports modified with covalently anchored imidazolium ionic liquids (ILs) containing different anions and cation lateral alkyl chain lengths by simple sputtering from a Ru foil. These Ru-NPs were active catalysts for the hydrogenation of benzene. Furthermore, depending on the nature of the IL used to modify the support (hydrophilic or hydrophobic), different catalytic behaviours were observed. Turnover numbers (TON) as high as 27 000 with a turnover frequency (TOF) of 2.73 s−1 were achieved with Ru-NPs of 6.4 nm supported in Al2O3 modified with an IL containing the N(SO2CF3)2− anion, whereas higher initial cyclohexene selectivities (ca. 20% at 1% benzene conversion) were attained for Ru-NPs of 6.6 nm in the case where Cl− and BF4− anions were used. Such observations strongly suggest that thin layers of ILs surround the NP surface, modifying the reactivity of these catalytic systems. These findings open a new window of opportunity in the development of size-controlled Ru-NPs with tuneable reactivity. [ABSTRACT FROM AUTHOR]

In this article, we have compared the anions of sodium salts (Is) and ionic liquids (ILs) with the stability and structure of α-chymotrypsin (CT), through fluorescence, thermal fluorescence analysis and circular dichroism (CD) spectroscopy. The experimental results revealed that the Hofmeister series of anions such as SCN−, SO42−, Cl−, Br−, CH3COO− and I− of Is destabilized the native structure of CT. On the contrary, the anions such as CH3COO−, Cl− and Br− of imidazolium-based IL with a fixed cation such as 1-butyl-3-methylimidazolium, [Bmim]+, stabilized the native structure of CT. The remaining anions of ILs such as SCN−, HSO4−, and I− acted as denaturing agents for the native structure of CT. Furthermore, molecular docking results show that the imidazolium-cation of the IL enters the sub-domains of CT and interacts with the ionic residues of CT, that is, Ser217 close to Trp215. This interaction is in well agreement with the fluorescence quenching observed for CT in the presence of [Bmim]+. On the other hand, the destabilizing anion such as SO42− was observed to be directly interacting with Ser195 in the active site of CT. We have observed that the Hofmeister series effects of anions of either Is or ILs are entirely based on the interaction of the anions with their counterions, that is, cations, with solvent molecules, as well as with the protein surface. Evidently, these interactions vary with the co-solvent system and the type of protein. Hence, the stability of a biomolecule in the presence of the anions may or may not obey the Hofmeister series. [ABSTRACT FROM AUTHOR]

Tri- and tetra-alkylimidazoles are quaternised into their corresponding ionic liquids with dimethyl carbonate. Upon metathesis of the obtained methyl carbonate salts, only gaseous by-products are generated. These methyl carbonate salts can be transformed into hydrogen carbonate salts by reaction with water. The salts containing a carbonate anion are very alkaline, which results in a hydrogen/deuterium exchange on the anion and some of the cation protons, depending on the substitution. Moreover, the crystalline 1-ethyl- 3,4,5-trimethylimidazolium hydrogen carbonate formed carboxylate species upon dissolution. In particular, the carboxylate was able to regenerate the carbene and in the presence of chloroform, this led to the formation of the chloride salt. [ABSTRACT FROM AUTHOR]

In this work a 1-(2-hydroxyethyl)-3-methylimidazolium nitrate ionic liquid, [HO(CH2)2mim]NO3, has been synthesized in order to serve as a new thermochromic material upon addition of cobalt(II) ions. Spectrophotometric measurements of a series of cobalt(II) nitrate and cobalt(II) chloride solutions in [HO(CH2)2mim]NO3 at 298.15, 308.15, 318.15, 328.15, and 338.15 K, were performed. Based on the recorded spectra, the overall stability constants and thermodynamic parameters for the cobalt(II) associations with chloride and nitrate ions were calculated. The thermodynamic calculations suggest that thermochromism is not observed in the ionic medium due to a small entropy change during the replacement of nitrate with chloride ions in the co-ordination sphere of cobalt(II). The absence of the molecular solvent was also the reason for the lack of thermochromism. Thus, cobalt(II) solutions in [HO(CH2)2mim]NO3 and water mixtures were studied as a new and green medium that can be used for the auto-regulation of the light intensity and shade protection. The investigated system with water upon addition of cobalt(II) was found to be a far more efficient and responsive thermochromic medium for all of the studied systems up until now. The structure of [HO(CH2)2mim]NO3 was confirmed by both ¹H NMR and IR spectroscopy. Also, the efficiency of different advanced oxidation processes (UV-induced photolysis, UV/H2O2 photolysis, heterogeneous photocatalysis using TiO2 Degussa P25 and TiO2 with 7.24%, w/w Fe catalysts) for [HO(CH2)2mim]NO3 degradation were investigated. The reaction intermediates formed during the photo-oxidation process were identified using LC-ESI-MS/MS and ¹H NMR techniques. [ABSTRACT FROM AUTHOR]

A series of novel heterogeneous catalysts were developed by immobilizing imidazolium-based functionalized ionic liquids on an FDU-type mesoporous polymer. Various techniques such as X-ray diffraction, N2 adsorption-desorption, and high resolution transmission electron microscopywere used to characterize the physicochemical properties of the catalysts. Ionic liquid-functionalized mesoporous polymers serve as efficient catalysts in the solvent free cycloaddition reactions of CO2 with epoxides without the use of any co-catalyst. The catalysts can be easily recovered and reused without a significant loss of activity. In comparison with the polystyrene (PS) and mesosilica SBA-15 supports, the FDU mesopolymer possesses both the mesoporous organic framework and abundant phenolic hydroxyl groups, which are key factors in improving the catalytic performance of supported ionic liquids. [ABSTRACT FROM AUTHOR]

An air stable, water soluble, and efficient ionic liquid-tagged Schiff base palladium complex was prepared. The synthesized complex was well characterized by NMR, mass spectrometry, FT-IR, UV-visible spectroscopy and powder X-ray diffraction. The complex was used as a catalyst for the Suzuki and Heck cross-coupling reactions in water. Good to excellent yields were achieved using a modest amount of the catalyst. In addition, the catalyst can be easily reused and recycled for six steps without much loss in activity, exhibiting an example of sustainable and green methodology. [ABSTRACT FROM AUTHOR]

Exploring ultrafast igniting and hydrolytically stable ionic liquids (ILs) has a wide scope in hypergolic rocket fuels. The hydrophobicities of ILs, induced by a smart change in alkyl substituents of imidazolium cations with energy-rich cyanoborohydride, [BH3CN]− and dicyanamide, [DCA]− anions were examined for the first time. The physico-chemical properties and performance of ILs were also studied. Consequently, hydrolytic stability in terms of moisture study of all the ILs was thoroughly investigated under standard environmental conditions. The analysis indicates that the IL 14, 1-allyl-3-octyl imidazolium cyanoborohydride is most hydrophobic and hydrolytically stable. Studies evaluating the role of the cationic hydrocarbon chain and the nature of anions of ILs on the properties of hypergolic fuel were carried out. All the ILs are liquid at room temperature and exhibit a positive heat of formation. IL 10, 1,3-diallyl-imidazolium cyanoborohydride exhibited the shortest ignition delay of 1.9 ms with WFNA and IL 11, 1-allyl-3-ethyl imidazolium cyanoborohydride presented the lowest viscosity of 16.62 mPa s. Therefore, these ILs can be suggested as potential candidates for replacing acutely toxic and carcinogenic hydrazine and its methylated derivatives as hypergolic fuels. [ABSTRACT FROM AUTHOR]

Imidazolium ionic liquid functionalized magnetic multiwalled carbon nanotubes (CNTs–Fe3O4–IL) were synthesized and the structure, morphology and properties of nanocomposites were investigated using different characterization techniques such as FT-IR, VSM, SEM, TEM, XRD, TGA and DTA. In order to synthesize CNT–Fe3O4–IL, magnetite supported on CNTs (CNT–Fe3O4) was modified with 1-methyl-3-(3-trimethoxysilylpropyl)-1H-imidazol-3-ium chloride. This nanocomposite was found to be an efficient organocatalyst for the synthesis of 2-amino-chromenes via a microwave-assisted multicomponent strategy in aqueous media. The attractive features of this simple method include easy isolation of products, milder and cleaner reaction conditions, higher yields and purity of the product and an easier work-up procedure. This heterogeneous catalyst was easily separated by simply applying an external magnetic field and the recyclable organocatalyst was reused several times without any significant loss of activity. A combination of the advantages of ionic liquids and magnetic solid support nanomaterials provides an environmentally benign procedure for carrying out catalytic processes. [ABSTRACT FROM AUTHOR]

A novel method to fabricate chemically linked conducting polymer–biopolymer composites that are intrinsically flexible and conducting for functional electrode applications is presented. Polypyrrole was synthesised in situ during the cellulose regeneration process using the 1-butyl-3-methylimidazolium chloride ionic liquid as a solvent medium. The obtained polypyrrole–cellulose composite was chemically blended and showed flexible polymer properties while retaining the electronic properties of a conducting polymer. Addition of an ionic liquid such as trihexyl(tetradecyl)phosphonium bis(trifluoromethylsulfonyl)imide, enhanced the flexibility of the composite. The functional application of these materials in the electrochemically controlled release of a model drug has been demonstrated. This strategy opens up a new design for a wide spectrum of materials for smart electronic device applications wherein the functionality of doping and de-doping of conducting polymers is retained and their processability issue is addressed by exploiting an ionic liquid route. [ABSTRACT FROM AUTHOR]

The solvothermal reaction of thorium nitrate and tris-(4-carboxylphenyl)phosphine oxide in DMF affords a centrosymmetric porous thorium organic framework compound [Th(TPO)(OH)(H2O)]·8H2O (1). In contrast, the ionothermal reaction of the same reagents in the ionic liquid 1-butyl-2,3-dimethylimidazolium chloride results in the formation of a rare example of a chiral and porous thorium organic framework compound, [C9H17N2][Th(TPO)Cl2]·18H2O (2), which is derived solely from achiral starting materials. The geometries of the Th(iv) centers in compounds 1 and 2 are both atypical for low valent actinides, which can be best described as a ten-coordinate spherical sphenocorona and an irregular muffin, respectively. A large cavity of 17.5 Å (max. face to face) × 8 Å (min. face to face) with a BET surface area of 623 m2 g−1 in compound 2 is observed. The poor stability indicated by thermal gravimetric analysis and the water-resistance test for compound 2 may be due to the unique anisotropic coordination geometry for thorium. Temperature-dependent luminescence studies for both compounds indicate that the trends in the intensity vary as the Th–Th distance and the coordination environments of Th(iv) centers change. [ABSTRACT FROM AUTHOR]

The article discusses a study that examined the use of aqueous ionic liquid buffer systems for fast and efficient DNA extraction from meat and meat derived products. Topics discussed include some of the ionic liquids used in the process are imidazolium, choline and guanidinium derivatives and results from the environmentally benign ionic liquid choline hexanoate-phosphate buffer mixture.