A nanocomposite made from conducting organic polymers and multi-walled carbon nanotubes for the adsorption and separation of gold(III) ions

We describe a new method for the separation and preconcentration of traces of Au(III) in environmental samples. Sorbents made from modified multiwalled carbon nanotubes and conducting polymers (PANI and PEDOT) were used for solid-phase extraction. The Au(III) ions are adsorbed as a result of the interaction with the electron pairs of =N- and -S- groups. Effects of pH value, flow rate and volume of sample, type, volume and concentration of eluent, and the adsorption capacity were investigated. The maximum adsorption capacity of MWCNTs/PANI and MWCNTs/PEDOT are 159 and 176?mg?g^?1, and the detection limits of this method are below 0.3 and 0.5?ng?mL^?1, respectively. The procedure was successfully applied to the determination of traces of Au(III) in a reference material and in environmental samples.

Hydrogenation of 2,4-Dinitrotoluene to 2,4-Diaminotoluene over Platinum Nanoparticles in a High-Pressure Slurry Reactor

A practical and convenient synthesis of the fungicidal natural compound farinomalein is described starting from readily available ethyl 3-methyl-2-oxobutyrate and triethyl phosphonoacetate, employing a Horner–Wadsworth–Emmons condensation as the key step.

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Hypersurfaces with too many rational curves

We study smooth hypersurfaces of degree \(d\ge n+1\) in \(\mathbf{P}^n\) whose spaces of smooth rational curves of low degrees are larger than expected, and show that under certain conditions, the primitive part of the middle cohomology of such hypersurfaces have non-trivial Hodge substructures. As an application, we prove that the space of lines on any smooth Fano hypersurface of degree \(d \le 8\) in \(\mathbf{P}^n\) has the expected dimension \(2n-d-3\) .     

In situ-generated N-thiocyanatosuccinimide (NTS) as a highly efficient reagent for the one-pot thiocyanation or isothiocyanation of alcohols

The first application of in situ-generated N-thiocyanatosuccinimide (NTS) for the thiocyanation of alcohols is described. This method can be easily applied for the facile conversion of primary, secondary and tertiary alcohols into the corresponding alkyl thiocyanates or alkyl isothiocyanates in good to excellent yields.     

Brief syntheses of (±)-methyl shikimate, (±)-methyl epishikimate and structural variants

Two brief syntheses of (±)-methyl shikimate are described in a strategy which offers potentially flexible access to a range of analogues. New intramolecular rearrangement reactions of epoxides derived from methyl 7-oxabicyclo[2.2.1]hept-3-ene 6-carboxylate and methyl bicyclo[2.2.1]hept-3-ene 6-carboxylate are described.     

Application of N-thiocyanatosuccinimide as a reagent for the facile conversion of epoxides into thiocyanohydrines

The use of in situ generated N-thiocyanatosuccinimide with NH₄SCN offers an efficient reagent system for the conversion of epoxides into their corresponding thiocyanohydrines in good to high yields.The major advantages of this method are as follows:use of cheap reagent,high regioselectivity,simple availability of reagent,ease of workup of the reaction.     

Electronic properties of bilayer and trilayer graphyne in the presence of electric field

The influence of electric field on the electronic properties of bilayer and trilayer graphyne has been studied using the density functional theory. We have investigated alpha graphyne due to its analogous to graphene. The bilayer and trilayer graphyne with different stacking style configurations have been considered. Our results indicate that the electronic properties of alpha graphyne are insensitive to the number of graphyne layer and configuration. The bilayer and trilayer graphyne are semimetal similar to the monolayer graphyne. It is found that applying a uniform electric field perpendicular to the graphyne sheet changes the electronic properties of AB-stacked bilayer and ABC-stacked trilayer graphyne so that they become semiconductor. The band gaps of the bilayer and trilayer graphyne with these configurations are enhanced by increasing strength of the electric field. Therefore, possibility of controlling the electronic properties of graphyne by applying electric field makes graphyne as a good candidate for next generation nanoelectronic devices.     

Recent developments in microextraction techniques based on crown ethers

Sample preparation is essential for isolating desired components from complex matrices and greatly influences their reliable and accurate analysis. Microextraction techniques such as solid phase micro extraction and liquid–liquid–liquid micro extraction based on hollow fiber and also single drop micro extraction methods are new and effective sample preparation techniques. Crown ethers are heterocyclic chemical compounds that consist of a ring containing several ether groups. Recently crown ethers have been applied in these methods and increase efficiency and selectivity of these techniques. Here we review the application of crown ethers in various micro extraction techniques.     

Synthesis,spectroscopic characterization,crystal structure and thermal analyses of two zinc(II) complexes with methanolysis of 2-pyridinecarbonitrile as a chelating ligand

Zinc(II) complexes, [Zn(MPCA)₃][ZnCl₄] (1) and [Zn(MPCA)₃][ZnBr₄] (2) (where MPCA is O-methylpyridine-2-carboximidate), were synthesized from the reaction of ZnCl₂ and ZnBr₂ with 2-pyridinecarbonitrile in methanol, respectively. Both complexes were thoroughly characterized by elemental analysis, thermogravimetric analysis, differential thermal analysis and IR, UV–Vis, ¹H NMR spectroscopy, and their structures have been determined by the single-crystal X-ray diffraction. The spectroscopic investigations and X-ray structural analysis indicated that in both complexes, the nitrile group of ligand has been methoximation in methanol solvent in the presence of zinc(II) salts. The luminescence spectra of both complexes show that the intensity of their emission bands is stronger than that of the bands for the free O-methylpyridine-2-carboximidate ligands.     

An efficient synthesis of ferrocenyl imidazo[1,2-a]pyridines

Abstract  

An efficient and simple synthesis of ferrocenyl 3-aminoimidazo[1,2-a]pyridines by the three-component reaction of ferrocenecarboxaldehyde, isocyanides, and 2-aminopyridines in the presence of a catalytic amount of InCl₃ in ethanol at room temperature is reported.