Ionic Liquid Assisted Synthesis of Au–Pd Bimetallic Particles with Enhanced Electrocatalytic Activity

Morphology‐ and composition‐controlled synthesis of Au–Pd bimetallic particles was realized by a facile ionic liquid assisted route at room temperature. The morphologies of the synthesized particles, such as nanoflake‐constructed spheres with a core–shell structure, nanoparticle‐constructed spheres, and nanoparticle‐constructed dendrites, could be well controlled by the present route. The ionic liquid was found to play a key role in the formation of these interesting particles. Moreover, the composition (Au:Pd) of the particles could be modulated by means of the molar ratio of the metal precursors in the feeding solutions. The Au–Pd bimetallic particles exhibit high electrocatalytic activity toward oxidation of ethanol and formic acid. Furthermore, cyclic voltammetric studies on the as‐prepared Au–Pd bimetallic particles revealed good electroactivity for H₂O₂, which results in an effective amperometric H₂O₂ sensor.     

Elucidation of the Electrochemical Oxidation Pathway of Ammonia in Dimethylformamide and the Room Temperature Ionic Liquid, 1‐Ethyl‐3‐methylimidazolium bis(trifluoromethylsulfonyl)imide

The direct electrochemical oxidation of ammonia has been examined in both the organic solvent dimethylformamide (DMF) and the room temperature ionic liquid 1‐ethyl‐3‐methylimidazolium bis(trifluoromethylsulfonyl)imide [EMIM][N(Tf)₂]. The corresponding voltammetric responses have been shown to be similar in each solvent with a broad oxidative wave occurring upon the introduction of ammonia to the solution and the appearance of a new reductive wave following the oxidation. The oxidative reaction process has been examined and a suitable reaction pathway has been deduced, corresponding to the formation of ammonium cations after oxidation of the ammonia. A linear response of limiting current against vol% ammonia was observed in both DMF and [EMIM][N(Tf)₂], suggesting potential application for analytical methods.     

Quantitative Analysis of Alpha‐D‐glucose in an Ionic Liquid by Using Infrared Spectroscopy

The applicability of infrared (IR) spectroscopy for quantitative concentration measurements in mixtures of carbohydrates and ionic liquids (ILs) is investigated. The compound 1‐ethyl‐3‐methylimidazolium acetate, [EMIM][OAc]—an “enzyme‐friendly” ionic liquid with great application potential in the dissolution of various biomasses—is used as solvent in combination with alpha‐D ‐glucose. Our study establishes a new way to monitor the concentration of sugars in ILs, thus providing a convenient method to follow the kinetics of, for example, enzymatic reactions in [EMIM][OAc]. As a first step, we present the IR spectrum of pure [EMIM][OAc] (this constitutes the first vibrational study of this particular IL). Although numerous lines overlap in the fingerprint region of the spectrum, characteristic features can be assigned to the corresponding vibrational modes of both ions. Secondly, we study different mixtures of the IL with alpha‐D ‐glucose (in the concentration range: 0–20 mass % glucose) and analyze them by means of IR spectroscopy, followed by computational methods, thus demonstrating the great potential of this spectroscopic technique in quantitative measurements.     

The performance of 1‐ethyl‐3‐methylimidazolium tetrafluoroborate ionic liquid as mobile phase additive in HPLC‐based lipophilicity assessment

Ionic liquids have been widely used as green alternative mobile phase additives to shield the residuals silanols groups and modify the stationary/mobile phase HPLC systems. The present study aimed to evaluate the performance of the ionic liquid 1‐ethyl‐3‐methylimidazolium tetrafluoroborate ([EMIM][BF4]) in producing extrapolated logk_w indices suitable to substitute for octanol–water logP or logD values. The effect of [EMIM][BF4] was investigated for a set of basic and neutral drugs using two different columns, BDS and ABZ⁺. [EMIM][BF4] was added simply alone or in combination with n‐octanol and was compared with the conventional masking agent n‐decylamine. [EMIM][BF4] reduced the retention by suppressing silanophilic interactions, althoug to a lower extent than n‐decylamine. Addition of n‐octanol further decreased the retention by shielding silanol sites on BDS and/or interacting with polar groups through hydrogen bonding on ABZ⁺. Logk_w/logD_7.4 relationships proved moderate compared with those derived upon addition of n‐decylamine. They were considerably improved upon the introduction of protonated fraction F⁺ in the correlation, reflecting ion pair formation between the chaotropic anion [BF4]^‐ and the protonated basic compounds. In this aspect, the ionic liquid [EMIM][BF4], although efficient as a masking agent, cannot be recommended as mobile phase additive to reproduce octanol–water partitioning. Copyright © 2010 John Wiley & Sons, Ltd.     

离子液体[EMIM][PF6]负载纳米SiOx表面的熔点及结构

制备了离子液体(1-乙基-3-甲基咪唑六氟磷酸 [EMIM][PF₆])负载量不同的多孔纳米氧化硅(SiO_x), 并采用差式扫描量热分析(DSC)、X射线衍射(XRD)、激光Raman光谱、傅里叶变换红外(FTIR)光谱分析等手段研究离子液体负载纳米氧化硅后的熔点变化及相行为. 研究表明负载于纳米氧化硅表面的离子液体熔点明显下降, 且负载于不同表面羟基含量的氧化硅表面熔点下降幅度不同. 纯离子液体[EMIM][PF₆]熔点为62 ℃, 在纳米氧化硅表面负载量为35%时熔点为52 ℃, 比负载前下降10 ℃; 负载于另两种不同羟基含量的纳米氧化硅表面后熔点分别下降20和17 ℃. 而同一种纳米氧化硅(比表面积为640 m²·g^-1)在负载量小于50%时, 熔点下降明显; 进一步增大负载量, 熔点逐渐趋于本体. XRD和Raman光谱分析显示, 离子液体负载于氧化硅表面后其衍射峰或吸收峰相对强度发生明显改变. 分析负载前后纳米氧化硅的结构变化, 推断离子液体熔点下降的主要原因是离子液体分子与纳米氧化硅表面之间存在强烈的界面相互作用, 而表面羟基的密度及比表面积是影响负载后[EMIM][PF₆]离子液体相行为的主要因素.     

Task‐specific Ionic Liquid Mediated Eco‐compatible Approach for the Synthesis of Spirooxindole Derivatives and Their DNA Cleavage Activity

Guanidine‐based task‐specific ionic liquid 1,1,3,3‐tetramethylguanidine acetate [TMG][Ac]was found to be a very effective solvent for the synthesis of pharmaceutically important spirooxindole derivatives through one‐pot multicomponent reaction of substituted isatin, thiazolidine‐4‐carboxylic acid and naphthoquinone followed by the spontaneous dehydrogenation in excellent yields without using any reagent and catalyst. The TMG‐based ionic liquid could be recovered and used at least four times without considerable reduction in its activity. The advantageous features of the developed synthetic protocol are high atom economy, operational simplicity, shorter reaction time, easily handling, and environmentally benign. The structure and relative stereochemistry of final products was established by single crystal X‐ray structure and spectroscopic techniques. The synthesized compounds were subjected for DNA cleavage activity.     

Spontaneous phase transfer of thermosensitive hairy particles between water and an ionic liquid

This article describes the temperature-induced phase transfer behavior of a series of thermosensitive polymer brush-grafted particles between water and a hydrophobic ionic liquid, 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ([EMIM][TFSI]). Six samples were made by surface-initiated atom transfer radical polymerization: silica particles grafted with poly(methoxypoly(ethylene glycol) methacrylate) (PPEGMMA) with two different molecular weights, poly(methoxytri(ethylene glycol) methacrylate) (PTEGMMA), poly(methoxydi(ethylene glycol) methacrylate) (PDEGMMA), and two copolymers of PEGMMA and TEGMMA with different compositions (P(PEGMMA-co-TEGMMA)-82 and P(PEGMMA-co-TEGMMA)-74). The cloud points of free PPEGMMA with M(n,SEC) of 23 and 40 kDa, P(PEGMMA-co-TEGMMA)-82, P(PEGMMA-co-TEGMMA)-74, and PTEGMMA in [EMIM][TFSI]-saturated water were 95, 94, 80, 72, and 43 °C, respectively. PDEGMMA was not soluble in the ionic liquid-saturated water. PPEGMMA brush-grafted particles moved spontaneously and completely from water to the [EMIM][TFSI] phase upon heating at 80 °C. When cooled to 22 °C, all particles returned to the water layer. From UV-vis absorbance measurements, the transfer temperature (T(tr)) of PPEGMMA-grafted particles from water to the ionic liquid was 42 °C. Thermodynamic analysis showed that the particle transfer was an entropically driven process. P(PEGMMA-co-TEGMMA)-82, P(PEGMMA-co-TEGMMA)-74, and PTEGMMA brush-grafted particles also underwent reversible and quantitative transfer between the two phases upon heating at 70 °C and cooling at 0 °C; their transfer temperatures from water to [EMIM][TFSI] were 36, 30, and 16 °C, respectively. T(tr) was a linear function of the cloud point of the corresponding free polymer in ionic liquid-saturated water. In contrast, PDEGMMA-grafted particles moved spontaneously to the ionic liquid layer upon heating but did not return to water even after prolonged stirring at 0 °C.     

Ionothermal synthesis and characterization of two new heteropolytungstates with 1-ethyl-3-methylimidazolium bromide ionic liquid as solvent

In this article, we have synthesized two new heteropolytungstate-based compounds [EMIM]₄[SiW₁₂O₄₀] (1) and [EMIM]₆[P₂W₁₈O₆₂] · 4H₂O (2) using the ionic liquid (IL) [EMIM]Br (EMIM = 1-ethyl-3-methylimidazolium) as a solvent and characterized them by infrared (IR) and ultraviolet (UV) spectra, thermogravimetric (TG) and elemental analyses, electrochemistry, and single-crystal X-ray analyses. Compound 1 is constructed from one [SiW₁₂O₄₀]^4? and four [EMIM]⁺. In the structure, [SiW₁₂O₄₀]^4? and [EMIM]⁺ are connected by hydrogen bonds with the surface oxygens of the polyoxoanion to form a 3-D supramolecular framework. The heteropolyanion of 2 is a classical Dawson-type structure [P₂W₁₈O₆₂]^6? and connected with six cations through hydrogen bonds. The structures of these two heteropolyanions are consistent with those synthesized by traditional methods, indicating that ionothermal synthesis is an effective method for the preparation of heteropolyoxometalates. The photocatalytic properties of these compounds have also been investigated.     

A facile synthesis of 3-allyl-4-hydrazinocyclopentenes by the palladium/Lewis acid mediated ring opening of bicyclic hydrazines with allyltributyltin and allyltrimethylsilane

A facile method for the synthesis of 3-allyl-4-hydrazinocyclopentenes from bicyclic hydrazines by the Pd/Lewis acid catalyzed reaction of allyltributyltin and allyltrimethylsilane is described. The role of ionic liquid [bmim]PF₆ as a solvent as well as a promoter is also demonstrated by carrying out the reactions in ionic liquid without Lewis acid.     

A novel one step synthesis of silver nanoparticles using room temperature ionic liquid and their biocidal activity

This article reports the synthesis of silver Nan particles (SNPs) using 1-(dodecyl) 2 amino-pyridinium bromide ionic liquid. This is a new one phase method for the synthesis of uniform monodispersed crystalline silver nanoparticles in a water-ionic liquid system. In this work, the functionalized room temperature IL acts as stabilizing agent and solvent. Hydrazine hydrate acts as reducing agent. To the best of our knowledge, there is no report of the synthesis of metal nanoparticles using this ionic liquid. The synthesis of silver nanoparticles is very primarily studied by UV-Visible spectroscopic analysis. The TEM and particle size distribution was used to study morphology and size of the particles. The charge on synthesized SNPs was determined by Zeta potential. The silver nanoparticles have been known to have inhibitory and bactericidal effect. The investigation of antibacterial activities of ionic liquid stabilized silver nanoparticles was performed by measurement of the minimum inhibitory concentration.     

Intramolecular electron transfer within a covalent, fixed-distance donor-acceptor molecule in an ionic liquid

Intramolecular photoinduced charge separation and recombination within the donor-acceptor molecule 4-(N-pyrrolidino)naphthalene-1,8-imide-pyromellitimide, 5ANI-PI, are studied using ultrafast transient absorption spectroscopy in the room-temperature ionic liquid, 1-ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)amide [EMIM][Tf2N]. The rate constants of both photoinduced charge separation and charge recombination for 5ANI-PI in [EMIM][Tf2N] are comparable to those observed in pyridine, which has a static dielectric constant similar to that of [EMIM][Tf2N] but a viscosity that is nearly 2 orders of magnitude lower than that of [EMIM][Tf2N]. The electron-transfer dynamics of 5ANI-PI in [EMIM][Tf2N] are compared to those in pyridine as a function of temperature and are discussed in the context of recently reported ionic liquid solvation studies.     

An Efficient One‐Pot Regioselective Approach Towards the Synthesis of Thiopyrano[2,3‐d]thiazole‐2‐thiones Catalyzed by Basic Ionic Liquid under Microwave Irradiation

A green, regioselective protocol for the synthesis of thiopyrano[2,3‐d]thiazole‐2‐thiones catalyzed by basic ionic liquid [bmIm]OH has been developed. The reaction proceeds smoothly under microwave irradiation, and high yields of the products are obtained in very short reaction times (5–11 min). The ionic liquid plays a dual solvent‐catalyst role.     

Vapor pressure measurement for water,methanol, ethanol,and their binary mixtures in the presence of an ionic liquid 1-ethyl-3-methylimidazolium dimethylphosphate

Vapor pressure data were measured for water, methanol and ethanol as well as their binary mixtures with an ionic liquid (IL) 1-ethyl-3-methylimidazolium dimethylphosphate ([EMIM][DMP]) at varying temperature and IL-content ranging from mass fraction of 0.10–0.70 by a quasi-static method. The vapor pressure data for the IL-containing binary systems were correlated using NRTL equation with average absolute relative deviation (ARD) within 0.0076, and the binary NRTL parameters was used for predicting the vapor pressure of the IL-containing ternary systems with reasonable accuracy. In addition, the infinite activity coefficients of solvents in [EMIM][DMP] and isobaric vapor–liquid equilibrium for IL-containing ternary systems at 101.325 kPa and mass fraction of IL being 0.5 were predicted with the regressed NRTL parameters. The results indicate that ionic liquid [EMIM][DMP] can depress the volatility of the solvents of water, methanol and ethanol but to a varying degree, leading to the variation of relative volatility of a solvent and even removal of azeotrope for water–ethanol mixture.     

An efficient and highly selective approach for the construction of novel dispiro heterocycles in guanidine-based task-specific [TMG][Ac] ionic liquid

A simple, efficient and highly selective one-pot approach for the synthesis of biologically important novel dispiro heterocycles assembling three pharmacophoric moieties such as piperidinone, 1,3-indanedione, and pyrrolidine in a single molecular framework by means of three-component reaction between ninhydrin, sarcosine, and 1-benzyl/methyl-3,5-bis[(E)-arylidene]-piperidin-4-one is reported in task-specific 1,1,3,3-tetramethylguanidine acetate [TMG][Ac] ionic liquid as a environmentally benign solvent in excellent yields without using any catalyst. The TMG-based ionic liquid could be recovered and used at least four times without considerable reduction in its activity and selectivity. Good functional group tolerance and broad scope of usable substrates are other prominent features of the present methodology with high degree of chemo-, regio-, and stereoselectivity. The structure and relative stereochemistry of final products were established by single crystal X-ray structure and spectroscopic techniques.     

Temperature- and pH-triggered reversible transfer of doubly responsive hairy particles between water and a hydrophobic ionic liquid

This article reports on the synthesis of thermo- and pH-sensitive polymer-brush-grafted silica particles ("hairy" particles) and the study of their phase-transfer behavior between water and a hydrophobic ionic liquid, 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)amide ([EMIM][TFSA]), in response to temperature and pH changes. The hairy particles were made by the surface-initiated atom transfer radical polymerization of methoxytri(ethylene glycol) methacrylate (TEGMMA) and tert-butyl methacrylate with a molar ratio of 100:11 in the presence of a free initiator and the subsequent removal of tert-butyl groups. The cloud points (CPs) of poly(TEGMMA-co-methacrylic acid), obtained after the treatment of the free polymer with trifluoroacetic acid, in both water and [EMIM][TFSA]-saturated water increased with the increase in pH and can be tuned over a wide temperature range. The hairy particles moved spontaneously from the aqueous phase to the [EMIM][TFSA] phase upon heating at 80 °C and returned to the aqueous layer upon cooling at 10 °C. This process can be repeated many times regardless of whether the pH of the aqueous phase is 2.99, 5.00, or 7.02. UV-vis absorbance measurements showed that the transfer temperature (T(tr)) of hairy particles from water to [EMIM][TFSA] increased with the increase in the pH of the aqueous phase. A linear relationship was observed between the T(tr) of hairy particles and the CP of the corresponding free polymer. By taking advantage of the tunability of the T(tr) of hairy particles, we demonstrated the pH-driven reversible transfer of hairy particles at a fixed temperature by changing the pH of the aqueous phase and multiple phase-transfer processes by controlling both the temperature and pH.     

Determination of ammonia based on the electro-oxidation of hydroquinone in dimethylformamide or in the room temperature ionic liquid, 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide

The results detail a novel methodology for the electrochemical determination of ammonia based on its interaction with hydroquinone in DMF. It has been shown that ammonia reversibly removes protons from the hydroquinone molecules, thus facilitating the oxidative process with the emergence of a new wave at less positive potentials. The analytical utility of the proposed methodology has been examined with a linear range from 10 to 95 ppm and corresponding limit-of-detection of 4.2 ppm achievable. Finally, the response of hydroquinone in the presence of ammonia has been examined in the room temperature ionic liquid 1-ethyl-3-methylimidazolium bis(trifluormethylsulfonyl)imide, [EMIM][N(Tf)₂]. Analogous voltammetric waveshapes to that observed in DMF were obtained, thereby confirming the viability of the method in either DMF or [EMIM][N(Tf)₂] as solvent.     

离子液体中卤素交换氟化合成七氟醚

在离子液体作为反应介质的条件下,以六氟异丙基氯甲基醚的氟代反应合成了七氟醚。 探讨了氟代反应机理,考察了[bpy]BF4、[bmim]BF4、[bepy]BF4、[bmim]PF6对反应产率的影响,研究了氟化剂、水和温度对反应产率的影响。 结果表明,以[bepy]BF4为反应介质,高比表面积的KF和微量的水有利于固态KF的部分离解进入有机相形成高活性的F-从而减少副产物,收率达到94.6%。 离子液体可重复使用3次以上,其活性没有明显下降。     

Liquid–Liquid Equilibrium Data for 1-Ethyl-3-methylimidazolium Acetate–Thiophene–Diesel Compound: Experiments and Correlations

Extraction of thiophene from cyclohexane, isooctane and toluene were performed using the ionic liquid 1-ethyl-3-methylimidazolium acetate ([EMIM][OAc]) at T=298.15 K. The liquid?Cliquid equilibrium (LLE) experiments were performed on three systems, namely: [EMIM][OAc]?Cthiophene?Ccyclohexane, [EMIM][OAc]?Cthiophene?Cisooctane and [EMIM][OAc]?Cthiophene?Ctoluene. The LLE data showed that [EMIM][OAc] has a higher selectivity at low concentration of thiophene and also showed that the hydrocarbon-rich phase is free of ionic liquid. This implies that there will be no cross contamination and the ionic liquid will be a non-pollutant in fuel after extraction. Further, the amount of hydrocarbon in the ionic-liquid-rich phase is very small. This implies that ionic liquid can be regenerated with negligible loss of fuel. LLE data was then correlated using the NRTL and UNIQUAC models. These showed root mean square deviation (RMSD) values of 0.82?% and 1.46?% for the isooctane system, 1.37?% and 1.57?% for the cyclohexane system and 1.39?% and 1.53?% for the toluene system.     

Benzimidazolyl based Schiff base palladium complex in an ionic liquid: an effective combination for Suzuki coupling

A new benzimidazole based Pd(II) Schiff base complex was prepared and its catalytic activity was evaluated for Suzuki cross-coupling reactions in ethyl-methyl imidazolium hexafluorophosphate [EMIM PF₆] ionic liquid at ambient temperature. The system provides a stable and reusable method for coupling reactions. Optimization for suitable reaction conditions were studied with respect to the effect of catalyst concentration, effects of additives, solvent and substituents on boronic acid. Good to excellent yields were achieved using a modest amount of the catalyst. The reaction time was less and the yield was more compared to previously reported results. In addition, the catalyst can be easily reused and recycled for six times without much loss in activity; this is an example of sustainable and green methodology.     

Polymersomes with ionic liquid interiors dispersed in water

We describe polymersomes with ionic liquid interiors dispersed in water. The vesicles are prepared via a simple and spontaneous migration of poly(butadiene-b-ethylene oxide) (PB-PEO) block copolymer vesicles from a hydrophobic ionic liquid, 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ([EMIM][TFSI]), to water at room temperature. As PB is insoluble in both water and [EMIM][TFSI] and PEO is well solvated in both media, the vesicles feature a PB membrane with PEO brushes forming both interior and exterior coronas. The robust and stable PB-PEO vesicles migrate across the liquid-liquid interface with their ionic liquid interiors intact and form a stabilized aqueous dispersion of vesicles enclosing microscopic ionic liquid pools. The nanostructure of the vesicles with ionic liquid interiors dispersed in water is characterized by direct visualization using cryogenic transmission electron microscopy. Upon heating, the vesicles can be quantitatively transferred back to [EMIM][TFSI], thus enabling facile recovery. The reversible transport capability of the shuttle system is demonstrated by the use of distinct hydrophobic dyes, which are selectively and simultaneously loaded in the vesicle membrane and interior. Furthermore, the fluorescence of the loaded dyes in the vesicles enables probing of the microenvironment of the vesicular ionic liquid interior through solvatochromism and direct imaging of the vesicles using laser scanning confocal microscopy. This vesicle system is of particular interest as a nanocarrier or nanoreactor for reactions, catalysis, and separations using ionic liquids.