Ionic Liquids as Novel Reaction Media for the Synthesis of Copoly(ester-amide)s Containing 9,10-Anthraquinone Moiety

The use of ionic liquids as novel solvents for the synthesis of aromatic copoly(ester-amide)s, containing a 9,10-anthraquinone moiety in the main chain, from the polycondensation reaction of terephthaloyl chloride and various ratios of p-phenylenediamine and 1,4-dihydroxyanthraquinone is reported. 1,3-Dialkylimidazolium-based ionic liquids are suitable reaction media for the synthesis of copoly(ester-amide)s. These copolymers exhibit color characteristics and thermal stability. The presence of the amide groups in the backbone of these polymers enhances their thermal stabilities. Inherent viscosities of the polymers obtained in 1,3-dialkylimidazolium bromide range from 0.28 to 0.42 dL/g.     

Construction of Antimagic Labeling for the Cartesian Product of Regular Graphs

An antimagic labeling of a graph with p vertices and q edges is a bijection from the set of edges to the set of integers {1, 2, . . . , q} such that all vertex weights are pairwise distinct, where a vertex weight is the sum of labels of all edges incident with the vertex. A graph is antimagic if it has an antimagic labeling. In 1990, Hartsfield and Ringel conjectured that that every connected graph, except K ₂, is antimagic. Recently, using completely separating systems, Phanalasy et al. showed that for each k 3 2, q 3 \binomk+12{k\geq 2,\,q\geq\binom{k+1}{2}} with k|2q, there exists an antimagic k-regular graph with q edges and p = 2q/k vertices. In this paper we prove constructively that certain families of Cartesian products of regular graphs are antimagic.     

Quantum computation of the properties of helium using two-body and three-body intermolecular potentials: a molecular dynamics study

We have performed the molecular dynamics simulation to obtain energy, pressure, and self-diffusion coefficient of helium at different temperatures and densities using Lennard–Jones (LJ), Hartree–Fock dispersion-Individual damping (HFD-ID) potential, and the HFD-like potential which has been obtained with an inversion of viscosity data at zero pressure supplemented by quantum corrections following the Feynman–Hibbs approach. The contribution of three-body interactions using an accurate simple relationship reported by Wang and Sadus between two-body and three-body interactions has been also involved for non-effective potentials (HFD-ID and HFD-like) in simulation. Our results show a good agreement with corresponding experimental data. A comparison of our simulated results with other molecular simulations using different potentials is also included.     

Manganese(III) porphyrin anchored onto multiwall carbon nanotubes: An efficient and reusable catalyst for the heterogeneous reduction of aldehydes and ketones

Reduction of a variety of carbonyl compounds with NaBH₄, using Mn-porphyrin, meso-tetrakis(4-hydroxyphenyl)porphyrinatomanganese(III), supported onto functionalized multiwall carbon nanotubes has been investigated. The heterogeneous catalyst was characterized by powder X-ray diffraction (XRD), transmission electron microscopy (TEM), and UV–vis spectroscopy. The amount of catalyst loading on the nanotubes was determined by atomic absorption spectroscopy. Thermogravimetric analysis (TGA) demonstrated that the nanocatalyst was thermally stable to almost 300 °C, exhibiting high thermostability of the catalyst over a broad range of temperatures. This heterogeneous catalyst proved to be an efficient catalyst in the aerobic reduction of various aldehydes and ketones with NaBH₄. In the presence of the nanocatalyst, NaBH₄ can readily reduce a variety of aldehydes in good to excellent yields (50–100%) and ketones in excellent yields (100%) to their corresponding alcohols. The separation of the catalyst is very simple and economic. Also, FTIR spectra after four successive cycles showed that the catalyst was strongly anchored to the nanotubes.     

Supramolecular dispersive liquid–liquid microextraction-based solidification of floating organic drops combined with electrothermal atomic absorption spectrometry for determination of chromium species

A simple, sensitive and reliable method has been developed for separation and preconcentration of chromium (VI) from aqueous samples before determination by electrothermal atomic absorption spectrometry. The method is based on the extraction of the hydrophobic complex of chromium (VI) with ammonium pyrrolidine dithiocarbamate in the coacervates made up of decanoic acid reverse micelles in the water–tetrahydrofuran mixture. Parameters affecting the extraction efficiency of the analyte were studied and optimised. Under the optimum conditions, the linear range, enhancement factor, the limit of detection and limit of quantification were found to be 0.008–0.4 µg L^?1, 127, and 1.8 ng L^?1 and 6.0 ng L^?1, of Cr(VI), respectively. The relative standard deviation at the concentration level of 0.1 µg L^?1 Cr(VI) (n = 6) was 4.2%. Total chromium was determined after the oxidation of Cr(III) to Cr(VI) with permanganate in acidic medium. The method was successfully applied to the determination of chromium species in water and human serum samples.     

Fabrication of cerium oxide nanoparticles: characterization and optical properties

Ceria (CeO(2)) is a technologically important rare earth material because of its unique properties and various engineering and biological applications. A facile and rapid method has been developed to prepare ceria nanoparticles using microwave with the average size 7 nm in the presence of a set of ionic liquids based on the bis (trifluoromethylsulfonyl) imide anion and different cations of 1-alkyl-3-methyl-imidazolium. The structural features and optical properties of the nanoparticles were determined in depth with X-ray powder diffraction, transmission electron microscope, N(2) adsorption-desorption technique, dynamic light scattering (DLS) analysis, FTIR spectroscopy, Raman spectroscopy, UV-vis absorption spectroscopy, and Diffuse reflectance spectroscopy. The energy band gap measurements of nanoparticles of ceria have been carried out by UV-visible absorption spectroscopy and diffuse reflectance spectroscopy. The surface charge properties of colloidal ceria dispersions in ethylene glycol have been also studied. To the best of our knowledge, this is the first report on using this type of ionic liquids in ceria nanoparticle synthesis.     

A rapid, one-pot, four-component route to 2H-indazolo[2,1-b]phthalazine-triones

A new, efficient, and environmentally benign protocol for the one-pot, four-component synthesis of 2,2-dimethyl-13-phenyl-2,3-dihydro-1H-indazolo[2,1-b]phthalazine-1,6,11(13H)-trione by condensation of phthalic anhydride, hydrazinium hydroxide, aromatic aldehydes, and dimedone catalyzed by Ce(SO₄)₂·4H₂O as an ecofriendly catalyst with high catalytic activity and reusability at 125 °C under solvent-free conditions is reported. The reaction proceeds to completion within 5-10 min in 71-95% yield. To the best of our knowledge, this new procedure provides the first example of an efficient synthetic method for 2H-indazolo[2,1-b]phthalazine-1,6,11(13H)-trione via a four-component reaction.     

Influence of acidic ionic liquids as an electrolyte additive on the electrochemical and corrosion behaviors of lead-acid battery

The aim of this study is to introduce the application of some acidic ionic liquids (ILs) as an electrolyte additive in lead-acid batteries. A family of alkylammonium hydrogen sulfate ILs, which are different in the number of alkyl chain, is investigated with the aim to compare their effects on the electrochemical behavior of Pb–Sb–Sn alloy in sulfuric acid solution. The hydrogen and oxygen gas evolution potential and anodic layer characteristics were investigated employing cyclic and linear sweep voltammetric methods. The morphological changes of the PbSO₄ layer that formed on the electrode surface were confirmed using scanning electron microscopy. Also, potentiodynamic polarization curves, electrochemical impedance spectroscopy, and an equivalent circuit analysis were used to evaluate the corrosion behaviors of the Pb–Sb–Sn alloy in the presence of ILs. The obtained results indicate that hydrogen and oxygen evolution overpotential of lead–antimony–tin alloy increases in the solution containing IL and mainly depends on the number of alkyl chain in alkylammonium cation. It is clearly observed that the morphology of PbSO₄ layer changes under the influence of ILs. The corrosion studies show an increase in corrosion resistance of lead alloy in the presence of some ILs. Also, the electrochemical effects of ILs in conversion of PbSO₄ to PbO₂ and vice versa were investigated by carbon-PbO paste electrode. Cyclic voltammogram of carbon-PbO electrode shows that in the presence of ILs, oxidation and reduction peak currents increase, while reversibility decreases.     

ZrOCl2·8H2O as an efficient and recyclable catalyst for the clean synthesis of xanthenedione derivatives under solvent-free conditions

ZrOCl₂·8H₂O was found to be an efficient and recyclable catalyst for the reaction of aromatic aldehydes with dimedone to afford 1,8-dioxo-1,2,3,4,5,6,7,8-octahydroxanthenes under solvent-free conditions. Short reaction time, excellent yields and simple work-up are the advantages of this procedure. The interaction obtained from XRD studies was shown that the catalyst loses H₂O during the reaction but it did not affect catalytic activity of the catalyst and the catalyst could be reused several times.     

Solubility of bosentan in {propylene glycol + water} mixtures at various temperatures: experimental data and mathematical modelling

Solubility measurements were performed for bosentan (BST) in binary mixtures of propylene glycol (PG) and water at atmospheric pressure within the temperature range, T = 293.2 – 313.2 K by employing a shake-flask method. Generated solubility data were correlated with Jouyban-Acree-van’t Hoff model and the accuracies of the predicted solubilities and model performance were illustrated by mean relative deviations (MRD). Furthermore, the apparent thermodynamic properties of BST dissolving in all the mixed solvents were calculated, and the obtained results show that the dissolution process is endothermic. By using the inverse Kirkwood–Buff integrals, it was observed that BST is preferentially solvated by water in water-rich solvent mixtures and preferentially solvated by PG (as a cosolvent) in the composition range of 0.20 < x₁ < 1.00 at 298.2 K.