Influence of ion structure on thermal runaway behaviour of aprotic and protic ionic liquids.

Accelerated rate calorimetric studies have been employed to study the exothermic and thermal runaway behaviour of some aprotic and protic ionic liquids based on several families of ions including the bis(flurorsulfonyl)imide anion ([FSI]-); it was found that the protic salts are safer than aprotic salts of the [FSI]- anion.

Thermo-electrochemical cells for waste heat harvesting - progress and perspectives.

Thermo-electrochemical cells (also called thermocells) are promising devices for harvesting waste heat for the sustainable production of energy. Research into thermocells has increased significantly in recent years, driven by advantages such as their ability to continuously convert heat into electrical energy without producing emissions or consuming materials. Until relatively recently, the commercial viability of thermocells was limited by their low power output and conversion efficiency. However, there have lately been significant advances in thermocell performance as a result of improvements to the electrode materials, electrolyte and redox chemistry and various features of the cell design. This article overviews these recent developments in thermocell research, including the development of new redox couples, the optimisation of electrolytes for improved power output and high-temperature operation, the design of high surface area electrodes for increased current density and device flexibility, and the optimisation of cell design to further enhance performance.

Electrochemical and physicochemical properties of small phosphonium cation ionic liquid electrolytes with high lithium salt content.

Electrolytes of a room temperature ionic liquid (RTIL), trimethyl(isobutyl)phosphonium (P111i4) bis(fluorosulfonyl)imide (FSI) with a wide range of lithium bis(fluorosulfonyl)imide (LiFSI) salt concentrations (up to 3.8 mol kg(-1) of salt in the RTIL) were characterised using a combination of techniques including viscosity, conductivity, differential scanning calorimetry (DSC), electrochemical impedance spectroscopy (EIS), nuclear magnetic resonance (NMR) and cyclic voltammetry (CV). We show that the FSI-based electrolyte containing a high salt concentration (e.g. 1 : 1 salt to IL molar ratio, equivalent to 3.2 mol kg(-1) of LiFSI) displays unusual transport behavior with respect to lithium ion mobility and promising electrochemical behavior, despite an increase in viscosity. These electrolytes could compete with the more traditionally studied nitrogen-based ionic liquids (ILs) in lithium battery applications.

Ionic liquids and ultrasound in combination: synergies and challenges.

Ionic liquids, as reaction media, and sonochemistry are two recently developing fields of chemistry that present some similarities. Firstly, they constitute separately unconventional approaches to reaction chemistry that, in many cases, generate improvements in yield, rate and selectivity compared to classical chemistry, or even change the mechanisms or products expected. In addition, both are often associated with green chemistry concepts as a result of their properties and their possible eco-friendly uses. A recent trend has been to combine these two technologies in a range of different applications and the results demonstrate very significant and occasionally surprising synergetic effects. Here we critically review the advantages and limitations of the ionic liquid/ultrasound combination in different applications in chemistry, to understand how, and in which respects, it could become an essential tool of sustainable chemistry in the future. Many practical and theoretical aspects associated with this combination of techniques are not understood or resolved and we discus where fundamental studies might further advance this field.

Ionic liquids for energy, materials, and medicine.

As highlighted by the recent ChemComm web themed issue on ionic liquids, this field continues to develop beyond the concept of interesting new solvents for application in the greening of the chemical industry. Here some current research trends in the field will be discussed which show that ionic liquids research is still aimed squarely at solving major societal issues by taking advantage of new fundamental understanding of the nature of these salts in their low temperature liquid state. This article discusses current research trends in applications of ionic liquids to energy, materials, and medicines to provide some insight into the directions, motivations, challenges, and successes being achieved with ionic liquids today.

Influence of Zn2+ and water on the transport properties of a pyrrolidinium dicyanamide ionic liquid.

In order to expand our understanding of a potential zinc-based battery electrolyte, we have characterized the physical and transport properties of the ionic liquid (IL) 1-butyl-1-methylpyrrolidinium dicyanamide ([C4mpyr][dca]) containing various levels of both Zn(2+) and H2O. Detailed measurements of density, viscosity, conductivity, and individual anion and cation diffusion coefficients using pulsed-field-gradient (PFG) NMR combined with NMR chemical shifts and spin-lattice relaxation (T1) NMR experiments provide insights into the motion and chemical environment of all molecular species. We find that the various techniques for probing ion transport and dynamics form a coherent picture as a function of electrolyte composition. Zn(2+) addition causes a moderate reduction in the self-diffusion of the IL anion and cation, whereas the addition of H2O increases ion mobility by increasing the liquid's overall fluidity. Temperature-dependent (13)C T1 experiments of the dca carbon analyzed using Bloembergen-Purcell-Pound fits show monotonic slowing of anion dynamics with Zn(2+) addition, suggesting increased Zn(2+)/dca(-) association. T1 experiments show minimal change in the spin-lattice relaxation of cation or anion upon H2O addition, suggesting that H2O is playing no significant role in Zn(2+) speciation. Finally, we employ a novel electrophoretic NMR technique to directly determine the electrophoretic mobility of the C4mpyr cation, which we discuss in the context of impedance-based conductivity measurements.

Curcumin loaded poly(2-hydroxyethyl methacrylate) nanoparticles from gelled ionic liquid--in vitro cytotoxicity and anti-cancer activity in SKOV-3 cells.

The main focus of this study is to encapsulate hydrophobic drug curcumin in hydrophilic polymeric core such as poly(2-hydroxyethyl methacrylate) [PHEMA] nanoparticles from gelled ionic liquid (IL) to improve its efficacy. We have achieved 26.4% drug loading in a biocompatible hydrophilic polymer. Curcumin loaded PHEMA nanoparticles (C-PHEMA-NPs) were prepared by nano-precipitation method. Scanning electron microscopy (SEM) and atomic force microscopy (AFM) analysis showed that the prepared nanoparticles were spherical in shape and free from aggregation. The size and zeta potential of prepared C-PHEMA-NPs were about 300 nm and -33.4 mV respectively. C-PHEMA-NPs were further characterized by FT-IR spectroscopy which confirmed the existence of curcumin in the nanoparticles. X-ray diffraction and differential scanning calorimetry studies revealed that curcumin present in the PHEMA nanoparticles were found to be amorphous in nature. The anticancer activity of C-PHEMA-NPs was measured in ovarian cancer cells (SKOV-3) in vitro, and the results revealed that the C-PHEMA-NPs had better tumor cells regression activity than free curcumin. Flow cytometry showed the significant reduction in G0/G1 cells after treatment with C-PHEMA-NPs and molecular level of apoptosis were also studied using western blotting. Toxicity of PHEMA nanoparticles were studied in zebrafish embryo model and results revealed the material to be highly biocompatible. The present study demonstrates the curcumin loaded PHEMA nanoparticles have potential therapeutic values in the treatment of cancer.

Bioenergetics for the growth of Staphylococcus lentus in biocompatible choline salts.

Choline-based biocompatible salts were used as "nutrients" for the growth of Staphylococcus lentus bacteria. Increase in the growth rate of bacteria was observed, compared to conventional carbon sources. In the case of the ionic liquid, choline lactate, the increase was pronounced. Bacterial growth was correlated with power-time curve in an investigation monitored online by reaction calorimetry. From the power-time curve, three phases of the growth can be distinctly seen. Heat yield coefficients estimated for the growth of S. lentus were found to match well with those reported hitherto. A comparative study of heat yields (catabolic) between glucose and choline lactate revealed significant information; the heat yield due to choline lactate (Y (Q/S)) consumption and oxygen (Y (Q/O)) were 23.4 kJ/g and 435 kJ/mol and whereas that for glucose with oxygen were 9.6 kJ/g and 427 kJ/mol, respectively, showing clearly the preferential affinity of choline lactate by the bacteria rather than glucose. This study also established that the use of ionic liquids as nutrients can be monitored using bioreaction calorimetry.

An organic ionic plastic crystal electrolyte based on the triflate anion exhibiting high proton transport.

A novel organic ionic plastic crystal (OIPC) electrolyte based on a quaternary ammonium cation and the triflate anion has been synthesized, which shows fast proton transport and high thermal stability in the solid state when doped with triflic acid.

The effect of coordinating and non-coordinating additives on the transport properties in ionic liquid electrolytes for lithium batteries.

In the present study we expand our analysis of using two contrasting organic solvent additives (toluene and THF) in an ionic liquid (IL)/Li NTf(2) electrolyte. Multinuclear Pulsed-Field Gradient (PFG) NMR, spin-lattice (T(1)) relaxation times and conductivity measurements over a wide temperature range are discussed in terms of transport properties and structuring of the liquid. The conductivity of both additive samples is enhanced the most at low temperatures, with THF slightly more effective than toluene. Both the anion and lithium self-diffusivity are enhanced in the same order by the additives (THF > toluene) while that of the pyrrolidinium cation is marginally enhanced. (1)H spin-lattice relaxation times indicate a reasonable degree of structuring and anisotropic motion within all of the samples and both (19)F and (7)Li highlight the effectiveness of THF at influencing the lithium coordination within these systems.

Biocompatibility of choline salts as crosslinking agents for collagen based biomaterials.

A series of novel choline based salts, some of which can be described as ionic liquids, are prepared and evaluated for their biocompatibility; when combined with collagenous biomaterials they exhibit good cell viability and adhesion properties as required for biomedical implant applications.

Exothermic and thermal runaway behaviour of some ionic liquids at elevated temperatures.

The exothermic behaviour and intrinsic safety of a number of ionic liquids being considered for battery and solar cell applications have been investigated at elevated temperatures by analysing data from accelerated rate calorimetric (ARC) studies.

Protic ionic liquids based on the dimeric and oligomeric anions: [(AcO)xH(x-1)]-.

We describe a fluidity and conductivity study as a function of composition in N-methylpyrrolidine-acetic acid mixtures. The simple 1 : 1 acid-base mixture appears to form an ionic liquid, but its degree of ionicity is quite low and such liquids are better thought of as poorly dissociated mixtures of acid and base. The composition consisting of 3 moles acetic acid and 1 mole N-methylpyrrolidine is shown to form the highest ionicity mixture in this binary due to the presence of oligomeric anionic species [(AcO)(x)H(x-1)](-) stabilised by hydrogen bonds. These oligomeric species, being weaker bases than the acetate anion, shift the proton transfer equilibrium towards formation of ionic species, thus generating a higher degree of ionicity than is present at the 1 : 1 composition. A Walden plot analysis, thermogravimetric behaviour and proton NMR data, as well as ab initio calculations of the oligomeric species, all support this conclusion.

On the electrodeposition of titanium in ionic liquids.

The ability to electrodeposit titanium at low temperatures would be an important breakthrough for making corrosion resistant layers on a variety of technically important materials. Ionic liquids have often been considered as suitable solvents for the electrodeposition of titanium. In the present paper we have extensively investigated whether titanium can be electrodeposited from its halides (TiCl(4), TiF(4), TiI(4)) in different ionic liquids, namely1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)amide ([EMIm]Tf(2)N), 1-butyl-1-methylpyrrolidinium bis(trifluoromethyl-sulfonyl)amide ([BMP]Tf(2)N), and trihexyltetradecyl-phosphonium bis(trifluoromethylsulfonyl)amide ([P(14,6,6,6)]Tf(2)N). Cyclic voltammetry and EQCM measurements show that, instead of elemental Ti, only non-stoichiometric halides are formed, for example with average stoichiometries of TiCl(0.2), TiCl(0.5) and TiCl(1.1). In situ STM measurements show that-in the best case-an ultrathin layer of Ti or TiCl(x) with thickness below 1 nm can be obtained. In addition, results from both electrochemical and chemical reduction experiments of TiCl(4) in a number of these ionic liquids support the formation of insoluble titanium cation-chloride complex species often involving the solvent. Solubility studies suggest that TiCl(3) and, particularly, TiCl(2) have very limited solubility in these Tf(2)N based ionic liquids. Therefore it does not appear possible to reduce Ti(4+) completely to the metal in the presence of chloride. Successful deposition processing for titanium in ionic liquids will require different maybe tailor-made titanium precursors that avoid these problems.

Coral larvae conservation: physiology and reproduction.

Coral species throughout the world's oceans are facing severe environmental pressures. We are interested in conserving coral larvae by means of cryopreservation, but little is known about their cellular physiology or cryobiology. These experiments examined cryoprotectant toxicity, dry weight, water and cryoprotectant permeability using cold and radiolabeled glycerol, spontaneous ice nucleation temperatures, chilling sensitivity, and settlement of coral larvae. Our two test species of coral larvae, Pocillopora damicornis (lace coral), and Fungia scutaria (mushroom coral) demonstrated a wide tolerance to cryoprotectants. Computer-aided morphometry determined that F. scutaria larvae were smaller than P. damicornis larvae. The average dry weight for P. damicornis was 24.5%, while that for F. scutaria was 17%, yielding osmotically inactive volumes (V(b)) of 0.22 and 0.15, respectively. The larvae from both species demonstrated radiolabeled glycerol uptake over time, suggesting they were permeable to the glycerol. Parameter fitting of the F. scutaria larvae data yielded a water permeability 2 microm/min/atm and a cryoprotectant permeability = 2.3 x 10(-4) cm/min while modeling indicated that glycerol reached 90% of final concentration in the larvae within 25 min. The spontaneous ice nucleation temperature for F. scutaria larvae in filtered seawater was -37.8+/-1.4 degrees C. However, when F. scutaria larvae were chilled from room temperature to -11 degrees C at various rates, they exhibited 100% mortality. When instantly cooled from room temperature to test temperatures, they showed damage below 10 degrees C. These data suggest that they are sensitive to both the rate of chilling and the absolute temperature, and indicate that vitrification may be the only means to successfully cryopreserve these organisms. Without prior cryopreservation, both species of coral settled under laboratory conditions.

Extraction and recovery of azo dyes into an ionic liquid.

The azo dyes are commonly used in the leather and textile industries as they are quite versatile in nature. However, they are neither totally utilised during the process, nor are they recovered at the end of the process. In fact, in the leather industry, typically about 10-15% of the dye is discharged with the effluent creating both environmental and economic issues. Hence, there is a need to remove the residual dye from the large volume of aqueous effluent. In this study, for the first time, azo dyes employed in the leather industry have been successfully extracted into a neutral ionic liquid, with an extraction efficiency of 98%, potentially providing a method of minimizing pollution of waste-waters. The extraction of the dye into the ionic liquid also provides a potential analytical approach to determination of these dyes.

Living cationic polymerisation of styrene in an ionic liquid.

For the first time, living cationic polymerisation of styrene has been carried out in room temperature ionic liquids under mild reaction conditions and using mild acid catalysts (e.g. organoborate acids) to obtain polymers of narrow polydispersity.

Reversible self-polymerizing high T(g) lyoprotectants.

One mode of action of protectants in the storage of biological materials is by promoting the formation of a vitrified state on cooling or drying. In the case of preservation by drying, the glassy material comprises a low water content mixture of protectant and organic material. The protectant must on drying form a glassy state of glass transition temperature (T(g)) above the desired storage temperature. However, in some applications it must also be easily transported through cell membranes and this restricts the choice to a relatively limited number of small molecules, which typically exhibit very low glass transition temperatures. In this work we describe a self-polymerizing protectant comprising an inorganic salt and a small hydroxy functional molecule such as glycerol. This forms co-ordinate polymer chains of high T(g) on drying but rapidly depolymerizes into the original components on rehydration. The polymerization process is general for polyhydroxy compounds including glucose and related compounds.

Sugars exert a major influence on the vitrification properties of ethylene glycol-based solutions and have low toxicity to embryos and oocytes.

A systematic approach was taken to assess the vitrification properties of ethylene glycol-based solutions supplemented with carbohydrates. Solutions were prepared by weight (gravimetrically) using ethylene glycol as the cryoprotectant, 0.9% NaCl in water, and six different sugars: d-glucose, d(-)-fructose, d-sorbitol, sucrose, d(+)-trehalose, and raffinose. Sugars were added on a molal basis (0. 1, 0.5, and 1 m). Characteristics of the solutions were measured during warming by differential scanning calorimetry using a cooling rate of 100 degrees C/min and a warming rate of 10 degrees C/min. In the absence of carbohydrates a 59 wt% EG-saline solution formed a stable glass. When EG was replaced by an equimolal concentration of glucose, fructose, or sorbitol (monosaccharides) at 0.1, 0.5, or 1.0 m there was no change in the total solute concentration at which vitrification occurred, but the glass transition (Tg) occurred at a higher temperature than in EG-saline alone. When EG was replaced by an equimolal concentration of sucrose or trehalose (disaccharides) both the Tg and the lowest total solute concentration required for vitrification became progressively higher as the molecular weight, or the ratio of sugar to EG in the solutions, increased. At the highest tested disaccharide concentration (1 m) vitrification was achieved at a total solute concentration of 65 wt% (sucrose) and 67 wt% (trehalose). The polysaccharide raffinose significantly modified the vitrification properties of ethylene glycol solutions. When 0.5 or 0.1 m raffinose replaced EG on an equimolal basis the glass transition point was raised more than with either the monosaccharides or the disaccharides. Raffinose allowed vitrification at a total solute concentration of 67 wt% (0.5 m) and 63 wt% (0.1 m). The maturation of immature mouse oocytes, and the development of embryos in media containing 5-7 mM of any sugar was comparable to controls, indicating that they are not toxic. Exposure of freshly collected GV or MII oocytes to sugar concentrations between 0.5 and 1.0 M, for up to 10 min had no significant effect on the proportion which subsequently formed two cells. We conclude that added sugars do contribute to a solutions overall vitrification properties, and their properties should be taken into consideration when vitrification solutions are being designed or modified.