Fabrication and characterization of copper nanoparticles using thermal reduction: The effect of nonionic surfactants on size and yield of nanoparticles

Thermal reduction has been applied to the preparation of copper nanoparticles (Cu-NPs) using three kinds of nonionic surfactants (Triton X-100, Tween-80, and dodecylamine). The Cu-NPs were formed by decomposition of copper(II) oxalate in presence of triphenylphosphine. The effect of the surfactants on the formation of the Cu-NPs was studied via X-ray diffraction, scanning electron microscopy, energy dispersive analysis of X-rays, transmission electron microscopy, thermogravimetric differential thermal analyses, and Fourier transform infra-red spectroscopy. It is shown that the Cu-NPs have an fcc crystal structure. Depending on the surfactant used, Cu-NPs with diameters between 8 and 20 nm can be prepared. The smallest Cu-NPs (8 nm) were formed in the presence of micelles of dodecylamine (yield 49%), while the largest particles (20 nm) were obtained with Triton X-100 (yield 99%). The use of Triton X-100 results in the highest yield and most uniform Cu-NPs.     

Optical Emission and Raman Spectroscopy Studies of Reactivity of Low-Pressure Glow Discharges in Ar–O<Subscript>2</Subscript> and He–O<Subscript>2</Subscript> Gas Mixtures with Coked Catalysts

We demonstrate that low-pressure glow discharges in He–O₂ gas mixture are effective in removing carbonaceous surface layers from coked catalysts. These discharges contain a number of reactive species including O, O₃, and O₂*, and all these could contribute in the decoking process. However, an evolving understanding is that the O atoms in the discharge have a predominant role in this. A working hypothesis is that the O atoms react with the coke to form CO, CO₂ and other carbon complexes. Online measurements using emission spectra from O, H, and CO in the discharges are compared for the cases of He–O₂ and Ar–O₂ gas mixtures. Under the reported experimental conditions the estimated reactivity of the He–O₂ discharges is considerably higher compared with discharges in the Ar–O₂ gas mixture. Raman spectroscopy is used to confirm the removal of the coke from the surface of Pt/Alumina catalyst.     

l-Proline-catalysed one-pot synthesis of tetrahydrobenzo[c]acridin-8(7H)-ones at room temperature

Only 10 mol% of l-Proline in ethanol proved to be a very efficient catalyst for the one-pot synthesis of a wide variety of highly substituted tetrahydrobenzo[c]acridin-8(7H)-ones at room temperature. The key advantages of this process are high yields, cost effectiveness of the catalyst, easy work-up and the products can be directly recrystallized from hot ethanol.     

Toward a practical and waste-free synthesis of thioureas in water

An operationally simple and entirely green protocol for the synthesis of thiourea derivatives by the reaction of carbon disulfide with primary amines in pure water is developed. This reaction is a highly atom-economic process for production of highly pure, hindered thioureas without any catalyst and tedious work-up.     

Template-based growth of titanium dioxide nanorods by a particulate sol-electrophoretic deposition process

TiO 2 nanorods have been successfully grown into a track-etched polycarbonate (PC) membrane by a particulate sol-electrophoretic deposition from an aqueous medium.The prepared sols had a narrow particle size distribution around 17 nm and excellent stability against aging,with zeta potentials in the range of 47-50 mV at pH 2.It was found that TiO 2 nanorods were grown from dilute aqueous sol with a low,0.1-M concentration.Fourier transform infrared spectroscopy (FT-IR) analysis confirmed that a full conversi...     

Aromatic poly(amide-ether)s containing naphthalene and methylene unites

1,5-Naphthene dioxy diacetic acid was synthesized from the reaction of 1,5-naphthalene diol and chloroacetic acid. It was used then as a bi-functiona l monomer in polycondensation reaction with aromatic diamines in the presence of tripnenylphosphite to produce poly(amide-ether)s. All the obtained polymers were characterized by IR and elemental analysis; their solubility behaviour was evaluated in polar organic solvents as well as in concentrated H₂SO₄. The extent of thermal stability and phase transitions of poly(amide- ether)s were investigated by thermogravimetric analysis and differential scanning calorimetry respectively; while the morphology was estimated by X-ray powder diffraction patterns. Besides, the fu-fu stacking character of polymer chain interactions in the solid state was confirmed by absorption spectra of solid thin films.     

An unusual bioactive oleanane triterpenoid from Rhododendron campanulatum D.Don

An unusual oleanane triterpene(1) was isolated from aerial parts of Rhododendron campanulatum.The compound had shown prominent antibacterial and immunomodulatory activities.The structure of the compound was determined by spectroscopic data including 1D and 2D NMR spectral analysis.