A new family of ionic liquids based on the 1-alkyl-2-methyl pyrrolinium cation

Five new salts based on 1-alkyl-2-methyl pyrrolinium ion are reported, two involving the iodide ion and three involving the bis(trifluoromethanesulfonyl) amide ion. The iodide salts have melting points around 100 °C, while the amide salts have melting points around room temperature. Two of the amide salts can be easily quenched into the glassy state and exhibit glass transition temperatures around −70 °C. The 2-methyl pyrrolinium cation bears structural similarities to the aromatic imidazolium cations on one hand and the cyclic ammonium cation family based on the pyrrolidinium cation on the other. The properties of the salts reported here are compared within these two related families of salts.

Air-assisted growth of tin dioxide nanoribbons

SnO₂ nanoribbons have been synthesized by annealing of a milled SnO₂ powder, which is able to evaporate efficiently at the temperature as low as 1100 °C due to the metastable structure created by ball milling treatment. When the milled powder was annealed in an assembly of two combustion boats, SnO₂ nanoribbons formed on the surface of the milled powder. The nanoribbons tend to grow along the [101] crystallographic direction and their side surfaces are represented by ±(010) and ±(101) facets. The oxygen plays an important role in enhancing their formation.

Nonadditivity of Faradaic currents and modification of capacitance currents in the voltammetry of mixtures of ferrocene and the cobaltocenium cation in protic and aprotic ionic liquids

Unexpected nonadditivity of currents encountered in the electrochemistry of mixtures of ferrocene (Fc) and cobaltocenium cation (Cc+) as the PF6 - salt has been investigated by direct current (dc) and Fourier-transformed alternating current (ac) cyclic voltammetry in two aprotic (1-butyl-3-methylimidazolium tetrafluoroborate and 1-butyl-3-methylimidazolium hexafluorophosphate) and three protic (triethylammonium formate, bis(2-hydroxyethyl)ammonium acetate, and triethylammonium acetate) ionic liquids (ILs). The voltammetry of the individual Fc0/+ and Cc+/0 couples always exhibits near-Nernstian behavior at glassy carbon and gold electrodes. As expected for an ideal process, the reversible formal potentials and diffusion coefficients at 23 ( 1 °C in each IL determined from measurement on individual Fc and Cc+ solutions were found to be independent of electrode material, concentration, and technique used for the measurement. However, when Fc and Cc+ were simultaneously present, the dc and ac peak currents per unit concentration for the Fc0/+ and Cc+/0 processes were found to be significantly enhanced in both aprotic and protic ILs. Thus, the apparent diffusion coefficient values calculated for Fc and Cc+ were respectively found to be about 25 and 35% larger than those determined individually in the aprotic ILs. A similar change in the Fc0/+ mass transport characteristics was observed upon addition of tetrabutylammonium hexafluorophosphate (Bu4NPF6), and the double layer capacitance also varied in distinctly different ways when Fc and Cc+ were present individually or in mixtures. Importantly, the nonadditivity of Faradaic current is not associated with a change in viscosity or from electron exchange as found when some solutes are added to ILs. The observation that the 1H NMR T1 relaxation times for the proton resonance in Cc+ also are modified in mixed systems implies that specific interaction with aggregates of the constituent IL ionic species giving rise to subtle structural changes plays an important role in modifying the mass transport, double layer characteristics, and dynamics when solutes of interest in this study are added to ILs. Analogous voltammetric changes were not observed in studies in organic solvent media containing 0.1 M added supporting electrolyte. Implications of the nonadditivity of Faradaic and capacitance terms in ILs are considered.

Synthesis of high surface area amorphous tin-zinc oxides by a sol-gel method

A new method to synthesize conducting oxide nanoparticles with low photocatalytic activity was investigated. Initially, the preparation of amorphous ZnO-SnO2 solid solution nanoparticles was studied using a sol-gel technique. It was found that X-ray amorphous nanopowders with low photocatalytic activity were produced when the precipitates were heat treated below 500 °C. However, FT-IR data showed that the sample may not be an oxide semiconductor. A mixture of ZnO and SnO2 crystalline nanoparticles was also produced at 800 °C and found to have much reduced photoactivity than commercial ZnO nanoparticles having a similar specific surface area.

Corrosion properties of a RF-magnetron-sputtered TiN coating deposited on 316L stainless steel

The effect of rf-power in the range from 100 to 200 W on the electrochemical properties of TiN coatings deposited on 316L stainless steel was investigated by using various electrochemical techniques in a 3.5-wt\% NaCl solution. Surface analyses were also conducted to analyze the coating characteristics. X-ray diffraction (XRD) and atomic force microscopy (AFM) analyses confirmed that increasing the rf-power led to a preferred orientation of the TiN(200) microstructure and decreased the surface roughness. The potentiodynamic test results confirmed the passive behavior of all of the specimens with low passive current densities and demonstrated that the effective pitting resistance of the TiN coatings increased with increasing rf-power. The electrochemical impedance spectroscopy (EIS) tests showed that the TiN films deposited with high rf-power had excellent corrosion resistance during an immersion time of 720 h due to their high total resistance and low porosity.

Role of cation in enhancing the conversion of the Alzheimer's peptide into amyloid fibrils using protic ionic liquids

We report on the impact of changes in the protic ionic liquid (pIL) cation on the fibrilisation kinetics and the conversion of the A 16-22 from monomers to amyloid fibrils. When we compare the use of primary, secondary, and tertiary amines we find that the primary amine results in the greatest conversion into amyloid fibrils. We show that the pIL is directly interacting with the peptide and this likely drives the difference in conversion and kinetics observed.

Synthesis and characterization of tin dioxide core-shell structure nanowires

In this study, one-dimensional and quasi-one-dimensional tin dioxide nanowires and nan-owalls were fabricated by the use of the chemical vapor deposition technique. It was demonstrated that the growth and nanostructure of tin oxide can be controlled by varying the thickness of gold layer and the partial pressure of vapor at growing sites. Nanowires with a core-shell structure, i.e., pure tin core and tin oxide shell, were synthesized from C-S_nO₂ powders at a mol ratio of C/S_nO₂=3/5 on both silicon and Lanthanum Strontium Co-balt Ferrite ceramic wafers through the vapor-solid mechanism. The conditions that are favorable to the growth of core-shell structure nanowires are investigated.

Gram-scale and template-free synthesis of ultralong tin disulfide nanobelts and their lithium ion storage performances

Ultralong SnS2 nanobelts with a high production yield up to _98% were synthesized via a gram-scale and template-free solvothermal route. The synthetic mechanism of these intriguing ultralong nanobelts was proposed to be from the synergetic effect of the layered CdI2-type structure of SnS2 and surfacemodification of the capping reagent dodecanethiol. The resulting SnS2 nanobelts showed a high specific capacity of 640 mA h g_1 and stable cycling ability (560 mA h g_1 after 50 cycles), which is much better than a graphite anode.