Use Of Room Temperature Ionic Liquids Research Articles

Synthesis of pyranobenzopyrans from D-glucal using ionic liquids

Imidazolium room temperature ionic liquids (RTILs) were used as solvents in the Lewis acid-catalyzed cycloaddition reactions of D-glucal with substituted salicylaldehydes. These reactions selectively led to various, novel, cis-pyrano [4,3-b]benzopyrans in modest yields, different products than those isolated from analogous solution studies. Furan diol was isolated as the major byproduct from all the reactions. The use of RTILs facilitated the use of unprotected sugars in these reactions.

Raman Wavelength Conversion in Ionic Liquids

We explore the use of room-temperature ionic liquids (ILs) as Raman wavelength converters. ILs provide an engineerable framework to design suitable liquids for wavelength conversion over a broad spectral range, through careful selection of the molecular structures of the IL anions and cations so that specific characteristics can be obtained, such as a desirable Raman shift, low Brillouin scattering, and good optical transmission in the pump and Stokes wavelengths. Applying such criteria, we demonstrate that 1-ethyl-3-methylimidazolium dicyanamide (EMIM DCA) is an effective medium for conversion of 532-nm pulses from a Q-switched Nd:YAG laser to 603 nm. This corresponds to an approximate 2200 cm−1 shift, which can be used to generate mid-infrared radiation through subsequent difference frequency generation for optical pumping of CO2 lasers. Threefold-higher Raman conversion efficiency is obtained in EMIM DCA compared with water under identical conditions in a proof-of-principle single-pass conversion setup, resulting in an efficient generation of multimillijoule, <6 ns duration, high-quality orange laser pulses in a wavelength region that is difficult to access at high energies. Consequently, we examine ILs representing two other classes of Raman-active functional groups and obtain conversion up to the fifth-order Stokes shift and first anti-Stokes shift. Through the tunable selection of their components and their useful dynamical properties, ILs provide a platform for efficient, simple, and alignment-tolerant high-energy Raman shifting with numerous industrial and technological applications.Received 16 June 2022Accepted 8 December 2022DOI:https://doi.org/10.1103/PhysRevApplied.19.014052© 2023 American Physical SocietyPhysics Subject Headings (PhySH)Research AreasChemical Physics & Physical ChemistryOptical sources & detectorsStimulated Raman scatteringPhysical SystemsIonic fluidsMoleculesOrganic compoundsTechniquesInfrared techniquesAtomic, Molecular & OpticalCondensed Matter, Materials & Applied PhysicsInterdisciplinary Physics

Role of Ionic Liquid Electrolytes As a Promoter for CO2 Electrocatalysis As Revealed By Vibrational Spectroscopy

Conversion of CO2 into chemicals and materials with an higher energy content makes CO2 electrolysis interesting for sustainable energy storage. One major strategy is to use electrochemical CO2 reduction reactions (CO2RR) in order to convert CO2 into CO, alcohols and formic acid. However, high overpotentials, competitive hydrogen evolution reaction (HER), as well as low product selectivity and Faraday efficiency, impairs CO2 electrolysis for applications so far. In order to reduce existing overpotentials, the use of room-temperature ionic liquids (RTILs) as promising electrolytes has gained much attention. That is because of their wide electrochemical window, excellent electric conductivity and high CO2 solubility. However, the reaction mechanism that is responsible for the drastically lower onset potentials for CO production from CO2RR, is for imidazolium based RTIL still controversial. Using in operando IR absorption and in situ sum-frequency generation (SFG) spectroscopy, we provide new information on the role of the imidazolium cations for CO2RR. For this purpose, we have studied Pt electrodes in contact with 1-butyl-3-methylimidazolium [BMIM], 1-butyl-2,3-dimethylimidazolium [BMMIM] and 1-butyl-1-methylpyrrolidinium bis(trifluoromethylsulfonyl)imide [BMPyrr][NTf2] RTILs that contained 10 to 500 mM H2O. Although, Pt catalysts have clear disadvantages in terms of costs and catalyst performance for CO2RR, because CO forms at low overpotentials but leads to catalyst poisoning and deactivation, the resulting limited number of side reactions renders Pt catalysts interesting for spectroscopic investigations that focus on the molecular origin of the existing low overpotentials. Cyclic voltammetry shows that Pt is active for CO2RR in all three RTILs, with the highest current densities in case of [BMMIM][NTf2]. SFG spectroscopy, demonstrates that CO forms at an onset potential of -0.7 V vs SHE, when [BMMIM] or [BMPyrr] cations and [NTf2] anions are present. This onset potential is independent of the H2O concentration and we propose that CO formation can occur predominantly via an electrostatically stabilized CO2 radical anion. On the other hand, in [BMIM][NTf2] electrolytes a strong dependence on the H2O concentration is observed for potentials <-0.4 V where we show that cations with an active C2 position at the imidazolium ring can act as co-catalysts that enables CO formation through a reactive imidazolium-2-carboxylic acid intermediate.

Effect of cavitation intensity control on self-assembling of alkanethiols on gold in room temperature ionic liquids

This study investigates the effect of cavitation intensity on self-assembling of alkanethiol molecules on gold in room temperature ionic liquids (RTILs) under low frequency ultrasound irradiation (20 kHz). The use of RTILs, with low vapor pressure, enabled cavitation activity to be controlled up to quenching through pressure decrease within an argon-saturated atmosphere. This control possibility was used to acquire deeper insights into the role of cavitation on self-assembling processes. It was shown by electrochemical, contact angles and Polarization Modulation - Infrared Reflection Absorption Spectroscopy (PM-IRRAS) measurements that cavitation activates orientation and organization of self-assembled monolayers (SAM). X-ray Photoelectron Spectroscopy (XPS) revealed that, even if chemical adsorption of molecules is highly activated under ultrasound irradiation, it is not dependent on acoustic cavitation intensity.

Electron Microscopy Imaging Applications of Room Temperature Ionic Liquids in the Biological Field: A Review.

For biological imaging using electron microscopy (EM), the use of room-temperature ionic liquids (RTILs) has been proposed as an alternative to traditional lengthy preparation methods. With their low vapor pressures and conductivity, RTILs can be applied onto hard-to-image soft and/or wet samples without dehydration - allowing for a more representative, hydrated state of material and opening the possibility for visualization of in situ physiological processes using conventional EM systems. However, RTILs have yet to be utilized to their full potential by microscopists and microbiologists alike. To this end, this review aims to provide a comprehensive summary of biological applications of RTILs for EM to bridge the RTIL, in situ microscopy, and biological communities. We outline future research avenues for the use of RTILs for the EM observation of biological samples, notably i) RTIL selection and optimization, ii) applications for live cell processes and iii) electron beam and ionic liquid interaction studies.

Review—Room-Temperature Ionic Liquids for Electrochemical Application with Special Focus on Gas Sensors

Room temperature ionic liquids (RTILs) are the most common electrolyte now a day, which is usually a molten salt comprised of cationic and anionic charge, generate a neutral species having high thermal stability and exceptional chemical property. Due to these unique properties, RTILs had been used for many applications as a solvent/electrolyte for decades. There are many RTILs, which possess good conductivity, as well as an optimum electrochemical window, which, is suitable for electrochemical sensor application. Among various electrochemical sensors available in the market, the electrochemical gas sensor is a popular device for environmental monitoring. The use of RTILs to the existing technology leads us to new era of sensing where we can able to address sensitivity, stability, robustness, and ability to do multiplex array along with the fundamental behind the electrochemical gas sensor. This paper is consisted of the electrical and electrochemical properties of some popular RTILs along with its application in electrochemical sensing, with a special focus on the electrochemical gas sensor. This review will help the general audience to fabricate the next-gen electrochemical sensor using RTILs.

Silver(I) chlorides speciation and its relationship to the design, construction and evaluation of true Ag(s)/[AgCln]1−n reference electrodes for their use in bis(trifluoromethylsulfonyl)imide room temperature ionic liquids

This study describes a methodology for the design of true reference electrodes of the second kind based on the chemical speciation of the system AgCl(s)/[AgCln]1−n in both homogeneous and heterogeneous systems in bis(trifluoromethylsulfonyl)imide room temperature ionic liquids (RTIL), based on measurements of the open circuit potential (OCP) of Ag(s) or Ag(s)|AgCl(s) indicator electrodes immersed in solutions of Ag [NTf2] and [C2mim]Cl in RTIL, as well as on representative potentiometric titrations of Ag(I) or of chloride ions in the same media. The found values of the apparent equilibrium constants of the chemical equilibrium processes associated to the electrode potential at the metal|RTIL interface, lay the foundation for the design of true reference electrode systems. To test the usefulness of the information collected during the chemical speciation of these systems, four true reference electrodes were built for their use in four imidazolium-based bis(trifluoromethylsulfonyl) RTIL, and their electrode potentials were determined over time using the [Co(Cp)2]+/0 or [Fe(Cp)2]+/0 redox couples as internal redox references. The aim of this work is to provide a simple method for the development and characterization of true reference electrodes for their use in RTIL, thus averting the use of QRE and enabling the construction of comparable potential scales in RTIL.

Extraordinary Slowing of Structural Dynamics in Thin Films of a Room Temperature Ionic Liquid.

The role that interfaces play in the dynamics of liquids is a fundamental scientific problem with vast importance in technological applications. From material science to biology, e.g., batteries to cell membranes, liquid properties at interfaces are frequently determinant in the nature of chemical processes. For most liquids, like water, the influence of an interface falls off on a ∼1 nm distance scale. Room temperature ionic liquids (RTILs) are a vast class of unusual liquids composed of complex cations and anions that are liquid salts at room temperature. They are unusual liquids with properties that can be finely tuned by selecting the structure of the cation and anion. RTILs are being used or developed in applications such as batteries, CO2 capture, and liquids for biological processes. Here, it is demonstrated quantitatively that the influence of an interface on RTIL properties is profoundly different from that observed in other classes of liquids. The dynamics of planar thin films of the room temperature ionic liquid, 1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide (BmimNTf2), were investigated using two-dimensional infrared spectroscopy (2D IR) with the CN stretch of SeCN– as the vibrational probe. The structural dynamics (spectral diffusion) of the thin films with controlled nanometer thicknesses were measured and compared to the dynamics of the bulk liquid. The samples were prepared by spin coating the RTIL, together with the vibrational probe, onto a surface functionalized with an ionic monolayer that mimics the structure of the BmimNTf2. Near-Brewster’s angle reflection pump–probe geometry 2D IR facilitated the detection of the exceedingly small signals from the films, some of which were only 14 nm thick. Even in quarter micron (250 nm) thick films, the observed dynamics were much slower than those of the bulk liquid. Using a new theoretical description, the correlation length (exponential falloff of the influence of the interfaces) was found to be 28 ± 5 nm. This very long correlation length, ∼30 times greater than that of water, has major implications for the use of RTILs in devices and other applications.

Electrochemistry of hydrogen evolution in ionic liquids aqueous mixtures

Use of room-temperature ionic liquids (RTILs) as electrolyte additives for highly efficient alkaline water electrolysis at low temperatures is evaluated. The hydrogen evolution reaction (HER) was studied with platinum cathode in 8 M KOH solution with and without addition of 2 vol.% of [Emim][MeSO3] in the 25–85 °C temperature range using voltammetry, chronoamperometry and electrochemical impedance spectroscopy measurements. Catalytic effect of IL’s presence in the electrolyte is evidenced for temperatures up to 45 °C by an increase of the exchange current density values, as well as a significant decrease of the overall impedance in the entire potential range. Thus, a lower activation energy of 38 kJ mol−1 is determined for HER in IL-added KOH compared to that of 48 kJ mol−1 for HER in IL-free KOH.

Room-Temperature Ionic Liquids and Biomembranes: Setting the Stage for Applications in Pharmacology, Biomedicine, and Bionanotechnology.

Empirical evidence and conceptual elaboration reveal and rationalize the remarkable affinity of organic ionic liquids for biomembranes. Cations of the so-called room-temperature ionic liquids (RTILs), in particular, are readily absorbed into the lipid fraction of biomembranes, causing a variety of observable biological effects, including generic cytotoxicity, broad antibacterial potential, and anticancer activity. Chemical physics analysis of model systems made of phospholipid bilayers, RTIL ions, and water confirm and partially explain this evidence, quantifying the mild destabilizing effect of RTILs on the structural, dynamic, and thermodynamic properties of lipids in biomembranes. Our Feature Article presents a brief introduction to these systems and to their roles in biophysics and biotechnology, summarizing recent experimental and computational results on their properties. More importantly, it highlights the many developments in pharmacology, biomedicine, and bionanotechnology expected from the current research effort on this topic. To anticipate future developments, we speculate on (i) potential applications of (magnetic) RTILs to affect and control the rheology of cells and biological tissues, of great relevance for diagnostics and (ii) the use of RTILs to improve the durability, reliability, and output of biomimetic photovoltaic devices.

Tribological study of imidazolium and phosphonium ionic liquid-based lubricants as additives in carboxylic acid-based natural oil: Advancements in environmentally friendly lubricants

This paper highlights the potential of a new family of environmentally sustainable, functional bio-lubricants called room temperature ionic liquids (RTILs). In this investigation, a tribometer was utilized to carry out friction and wear experiments under ambient conditions to investigate the use of imidazolium and phosphonium-based RTIL's. The study investigated the tribological functionality of RTIL's as additives in plant-based avocado oil and as green sustainable fluids. The use of RTIL as additives in natural oil revealed that a higher percentage mix of RTILs can linearly improve the tribological performance. It was found that, depending on the type and percentage mix of RTIL with avocado oil, the coefficient of friction (COF) could be reduced by as much as 68.88% and the wear volume could be reduced by 73.37%. The RTILs were able to reduce the COF and wear volume not only when used as additives but also when used as base lubricating fluids. It was found that this was a result of the more resilient carboxylate acid-based monolayers that influenced the boundary lubrication regime. The present study details the influence of RTILs as additives, and the role of additive concentration in controlling the tribological performance to aid cleaner production research. Further, the study discusses their future as sustainable lubricants, and their underlying lubrication mechanisms.

Lipase Activation and Stabilization in Room-Temperature Ionic Liquids.

Widespread interest in the use of room-temperature ionic liquids (RTILs) as solvents in anhydrous biocatalytic reactions has largely been met with underwhelming results. Enzymes are frequently inactivated in RTILs as a result of the influence of solvent on the enzyme's microenvironment, be it through interacting with the enzyme or enzyme-bound water molecules. The purpose of this chapter is to present a rational approach to mediate RTIL-enzyme interactions, which is essential if we are to realize the advantages of RTILs over conventional solvents for biocatalysis in full. The underlying premise for this approach is the stabilization of enzyme structure via multipoint covalent immobilization within a polyurethane foam matrix. Additionally, the approach entails the use of salt hydrates to control the level of hydration of the immobilized enzyme, which is critical to the activation of enzymes in nonaqueous media. Although lipase is used as a model enzyme, this approach may be effective in activating and stabilizing virtually any enzyme in RTILs.

Quantum and Classical Molecular Dynamics of Ionic Liquid Electrolytes for Na/Li-based Batteries: Molecular Origins of the Conductivity Behavior.

Compositional effects on the charge-transport properties of electrolytes for batteries based on room-temperature ionic liquids (RTILs) are well-known. However, further understanding is required about the molecular origins of these effects, in particular regarding the replacement of Li by Na. In this work, we investigate the use of RTILs in batteries, by means of both classical molecular dynamics (MD), which provides information about structure and molecular transport, and ab initio molecular dynamics (AIMD), which provides information about structure. The focus has been placed on the effect of adding either Na(+) or Li(+) to 1-methyl-1-butyl-pyrrolidinium [C4 PYR](+) bis(trifluoromethanesulfonyl)imide [Tf2 N](-) . Radial distribution functions show excellent agreement between MD and AIMD, which ensures the validity of the force fields used in the MD. This is corroborated by the MD results for the density, the diffusion coefficients, and the total conductivity of the electrolytes, which reproduce remarkably well the experimental observations for all studied Na/Li concentrations. By extracting partial conductivities, it is demonstrated that the main contribution to the conductivity is that of [C4 PYR](+) and [Tf2 N](-) . However, addition of Na(+) /Li(+) , although not significant on its own, produces a dramatic decrease in the partial conductivities of the RTIL ions. The origin of this indirect effect can be traced to the modification of the microscopic structure of the liquid as observed from the radial distribution functions, owing to the formation of [Na(Tf2 N)n ]((n-1)-) and [Li(Tf2 N)n ]((n-1)-) clusters at high concentrations. This formation hinders the motion of the large ions, hence reducing the total conductivity. We demonstrate that this clustering effect is common to both Li and Na, showing that both ions behave in a similar manner at a microscopic level in spite of their distinct ionic radii. This is an interesting finding for extending Li-ion and Li-air technologies to their potentially cheaper Na-based counterparts.

Room Temperature Ionic Liquids as Green Solvent Alternatives in the Metathesis of Oleochemical Feedstocks

One of the most important areas of green chemistry is the application of environmentally friendly solvents in catalysis and synthesis. Conventional organic solvents pose a threat to the environment due to the volatility, highly flammability, toxicity and carcinogenic properties they exhibit. The recently emerged room temperature ionic liquids (RTILs) are promising green solvent alternatives to the volatile organic solvents due to their ease of reuse, non-volatility, thermal stability and ability to dissolve a variety of organic and organometallic compounds. This review explores the use of RTILs as green solvent media in olefin metathesis for applications in the oleochemical industry.

Supported UV Polymerized Ionic Liquid Membranes with Block Copolymer

In this study, the use of UV polymerizable Room Temperature Ionic Liquid (RTIL) with a block copolymer has been investigated for the generation of composite membranes for potential separation of acidic gases from natural gas streams. Use of RTILs is known to provide significant mass transportation enhancement but with significant shortcomings such as leaching. In order to avoid this limitation, UV polymerized RTIL membranes with poly(ether-bamide) have been generated with superior mechanical and thermal properties. Two different synthetic approaches were utilized in the current study to obtain the supported membranes with different structural aspects, thus, confirming the possibility to control the structure and resulting properties of the membranes.

All Solid State Carbon Based Supercapacitor with Ionogel As Electrolyte

Electrochemical Double Layer Capacitors (EDLCs), so called supercapacitors, represent a growing part of energy storage devices. Their interest lies in their ability to store more energy than conventional capacitors and to deliver more power than secondary batteries. Common supercapacitors involve activated carbon electrodes and organic solvent based electrolytes. These electrolytes have a good ionic conductivity and a broad electrochemical window (2.5 – 2.7 V in symmetric devices) but their liquid state and flammability entail safety issues. Room temperature ionic liquids (RTILs) are under consideration for the replacement of organic electrolytes since they have a fair ionic conductivity (~1-10 mS.cm-1) and a broad temperature operating range, but their main advantage is related to their safety compared to standard organic solvents. Indeed, RTIL show negligible volatility and no flammability when chosen adequately. RTILs are only composed of anions and cations (without any solvent), and are liquid around room temperature. The use of RTIL in different designs can further improve their properties. One of the most interesting examples is their confinement in a host matrix, which prevents from any possible leakage, and in which their liquid state properties are maintained. Such an electrolyte, named ionogel, could permit to increase considerably the safety of energy storage devices such as EDLCs, based on both RTIL properties as well as on their solid-like shaping. Typical activated carbon electrodes (Norit S50 as activated carbon / Super P as conductive carbon / PVDF-HFP as binder with respective proportions 80 / 10 / 10 wt%, overall ~1mg.cm-2) were deposited onto aluminium current collectors for prototyping. The ionogel was synthesized via sol-gel route with alkoxysilane as silica precursor, RTIL as solvent and formic acid as sol-gel catalyst: the resulting monolithic mesoporous silica hosts the RTIL. The reactants were mixed and casted onto carbon electrodes during a single step process. At the same time, a thick, self-standing, ionogel was made for ionic conductivity measurements. After 5 days of aging, the ionogel was dried in a Buchi (60°C, 0.5 mbar) overnight to remove the residual water. The ionic conductivity of the ionogel, measured in a Swagelok cell under argon, was 1.5 mS.cm-1 at 20 °C. A symmetric all solid state EDLC was assembled using two carbon electrodes with ionogel deposit. After drying following previous process, the device was compared with an EDLC using glass microfiber separator impregnated with the same pristine RTIL. All electrochemical measurements were performed under argon. Cyclic voltammetry experiments demonstrated no capacitance loss when the ionogel was used instead of the pristine RTIL, and the electrochemical stability was maintained up to 2.5 V. An acceptable value at 80 F.g-1 for the gravimetric capacitance was reached ();this showed a good impregnation of the activated carbon by either the pristine RTIL or by the ionogel’ sol precursors. Galvanostatic cycling were performed between 0 V and 2.5 V at 1 mA.g-1 for 10,000 cycles with efficiency above 98 % and no significant capacitance loss.

Molecularly "wired" cholesterol oxidase for biosensing.

The influence of several factors on the activity of cholesterol oxidase (ChOx) transiently exposed to a room temperature ionic liquid (RTIL) was studied. Presence of flavin adenine dinucleotide (FAD, prosthetic group of ChOx) during exposure to RTIL makes the procedure enzyme-friendly, while the use of RTIL (green reagent) makes it environmentally-friendly. Following exposure to RTIL and its subsequent removal, FAD becomes part of the molecular structure of the refolded protein (a molecular "wire"). This makes the procedure used here a molecular one. The factors studied were: FAD presence in RTIL during modification, water presence during exposure to RTIL, and ratio FAD:RTIL during "wiring". Performance parameters monitored were: enzyme activity before and after "wiring" (expressed as (dA/dt)/mg enzyme, and measured spectrophotometrically), peak current in an amperometric biosensor for cholesterol detection, and linearity of the biosensor response depending on cholesterol concentration. After RTIL removal, the modified enzyme (ME) retained a high percentage of the added FAD, which supplemented that of the native enzyme (functioning as a "wire" and enhancing electron transfer kinetics), and a fraction of the initial activity. Used in an amperometric biosensor, ME showed catalytic activity, linear behavior as a function of cholesterol concentration, and stability.

Mixed hemimicelles solid-phase extraction based on ionic liquid-coated Fe3O4/SiO2 nanoparticles for the determination of flavonoids in bio-matrix samples coupled with high performance liquid chromatography

A novel magnetic solid-phase extraction (MSPE) method based on mixed hemimicelles of room temperature ionic liquids (RTILs) coated Fe3O4/SiO2 nanoparticles (NPs) was developed for simultaneous extraction of trace amounts of flavonoids in bio-matrix samples. A comparative study on the use of RTILs (C16mimBr) and CTAB-coated Fe3O4/SiO2 NPs as sorbents was presented. Owing to bigger adsorption amounts for analytes, RTILs-coated Fe3O4/SiO2 NPs was selected as MSPE materials and three analytes luteolin, quercetin and kaempferol can be quantitatively extracted and simultaneously determined coupled with high performance liquid chromatography (HPLC) in urine samples. No interferences were caused by proteins or endogenous compounds. Good linearity (R2>0.9993) for all calibration curves was obtained, and the limits of detection (LOD) for luteolin, quercetin and kaempferol were 0.10ng/mL, 0.50ng/mL and 0.20ng/mL in urine samples, respectively. Satisfactory recoveries (93.5–97.6%, 90.1–95.4% and 93.3–96.6% for luteolin, quercetin and kaempferol) in biological matrices were achieved. It was notable that while using a small amount of Fe3O4/SiO2 NPs (4.0mg) and C16mimBr (1.0mg), satisfactory preconcentration factors and extraction recoveries for the three flavonoids were obtained. To the best of our knowledge, this is the first time a mixed hemimicelles MSPE method based on RTILs and Fe3O4/SiO2 NPs magnetic separation has ever been used for pretreatment of complex biological samples.

Applications of Surface Modified Ionic Liquid/Nanomaterial Composite in Electrochemical Sensors and Biosensors

Nanotechnology is playing an important role in the development of biosensors. The exclusive physical and chemical properties of nanomaterials make them exceptionally suitable for designing new and improved sensing devices, especially electrochemical sensors and biosensors. Room temperature ionic liquids (RTILs) are salts that exist in the liquid phase at and around 298 K and are entirely composed of ions: a bulky, asymmetric organic cation and usually an inorganic anion but some ILs also has organic anion. ILs have received much attention as a replacement for traditional volatile organic solvents as they possess many attractive properties such as intrinsic ion conductivity, low volatility, high chemical and thermal stability, low combustibility, and wide electrochemical windows, etc. Due to negligible or nonzero volatility of these solvents, they are considered “greener” for the environment in comparison to volatile organic compounds. ILs have been widely used in electrodeposition, electrosynthesis, electrocatalysis, electrochemical capacitor, lubricants, plasticizers, solvent, lithium batteries, solvents to manufacture nanomaterials, extraction, gas absorption agents etc. [1, 2, 3, 4]. This review discusses the electrochemical sensors and biosensors based on carbon nanotubes, metal oxide nanoparticles, and ionic liquid/composite modified electrodes. The main thrust of the review is to present an overview on the advantages of use of RTILs along with nanomaterials for electrochemical sensors and biosensors. Consequently, recent developments and major strategies for enhancing sensing performance have been thoroughly discussed.

Efficient solvent system containing malonamides in room temperature ionic liquids: actinide extraction, fluorescence and radiolytic degradation studies

Solvent extraction studies of actinide metal ions such as Am(III), U(VI), Np(IV), Np(VI), Pu(IV) were carried out in a nitric acid medium using two diamides (L) viz. (DMDBTDMA (N,N'-dimethyl-N,N'-dibutyl-2-tetradecylmalonamide) and DMDOHEMA (N,N'-dimethyl-N,N'-dioctyl-2-(2'-(hexyloxy)ethyl)-malonamide) dissolved in different room temperature ionic liquids (RTILs). The use of RTILs as the diluent significantly enhanced metal ion extraction as compared to that observed in non polar diluent such as n-dodecane. The effects of parameters such as kinetics, aqueous phase acidity (0.01-3 M HNO(3)), metal ion oxidation states, diamide concentration on the extraction of metal ions were studied. The stoichiometry of the extracted Am(III) species using these diamides varied with ligand concentration viz. (Am.3L)(3+) ([L] = 0.005-0.02 M) and (Am.2-2.5L)(3+) ([L] = 0.05-0.1 M). Time resolved laser induced fluorescence spectroscopy (TRLFS) studies showed that the extracted species of Eu(III) in an ionic liquid medium had no coordinated water molecules, in contrast to the presence of 1-2 water molecules in the extracted species in a n-dodecane medium. The radiolytic degradation behavior of the diamides/RTIL system has been studied using IR spectroscopy and gas chromatography-mass spectrometry (GC-MS). The data revealed that a significantly lower ligand concentration is required for actinide extraction in ionic liquids as the extraction media as compared to nonpolar diluents.