Molybdenum Schiff base-polyoxometalate hybrid compound: A heterogeneous catalyst for alkene epoxidation with tert-BuOOH

The hybrid compound consisting of molybdenum(salen) [salen = N,N′-bis(salicylidene)ethylnediamine] complex covalently linked to a lacunary Keggin-type polyoxometalate, K₈[SiW₁₁O₃₉] (POM), was synthesized and characterized by elemental analysis, FT-IR, ¹H NMR and diffuse reflectance UV–Vis spectroscopic methods and BET analysis. The complex, [Mo(O)₂(salen)–POM], was studied, for the first time, in the epoxidation of various alkenes with tert-BuOOH and in 1,2-dichloroethane as solvent. This catalyst can catalyze epoxidation of various olefins including non-activated terminal olefins. The effect of the other parameters such as solvent, oxidant and temperature on the epoxidation of cyclooctene was also investigated. The interesting characteristic of this catalyst is that, in addition to being a heterogeneous catalyst, it gives higher yields towards epoxidation of olefins in comparison to the corresponding homogeneous [Mo(O)₂(salen)] complex.     

Silica supported Ru(salophen)Cl: An efficient and robust heterogeneous catalyst for epoxidation of alkenes with sodium periodate

In the present work, heterogenization of Ru(salophen)Cl via its axial ligation to silica-bound imidazole, SiIm, is reported. The heterogeneous catalyst, [Ru(salophen)Cl–SiIm], was characterized by elemental analysis, SEM, TEM, FT-IR and diffuse reflectance UV–Vis spectroscopic techniques. The catalyst, which is not soluble in water and common organic solvents, was used for efficient epoxidation of cyclic and linear alkenes with NaIO₄ under agitation with magnetic stirring. This new heterogenized catalyst is of high stability and reusability in the oxidation reactions. The effect of reaction parameters such as solvent and oxidant in the epoxidation of cis-cyclooctene were also investigated.     

Computation of some thermodynamic properties of helium–neon and helium–krypton fluid mixtures using molecular dynamics simulation

We have performed molecular dynamics simulations to obtain internal energy and pressure of helium–neon and helium–krypton mixtures at different densities using accurate recently two-body ab initio potentials supplemented by quantum corrections following the Feynman–Hibbs approach. The significance of this work is that the three-body expression of Wang and Sadus [22] was used to improve prediction of the pressures and internal energies of helium + krypton and helium + neon mixtures without requiring an expensive three-body calculation. Our results show a good agreement with the corresponding experimental data.     

Thermal decomposition route for synthesis of Mn3O4 nanoparticles in presence of a novel precursor

The synthesis of manganese oxide (Mn₃O₄) nanoparticles by using thermal decomposition and its physicochemical characterization are being reported in present investigation. As a new precursor, [bis(2-hydroxy-1-naphthaldehydato)manganese(II)] complex was used in the presence of oleylamine (C₁₈H₃₇N) as both surfactant and solvent to control the size of resulting nanoparticle. The products were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), Fourier transform infrared (FT-IR) spectroscopy, thermogravimetric analysis (TGA), X-ray photoelectron spectroscopy (XPS) and Raman spectrum. Synthesized manganese oxide nanoparticles have a tetragonal structure with average size of 9–24 nm. The phase pure samples were characterized by using X-ray photoelectron spectroscopy (XPS) for Mn 2p level. The values of binding energies are consistent with the relative values are reported in the literature. As a comparison between two methods, the novel precursor thermally was treated in solid state reaction in different temperature, 400, 500, and 600 °C and the products were characterized by SEM images. Magnetic property of the as-prepared Mn₃O₄ nanoparticle shows a ferromagnetic behavior with high saturation magnetization and coercivity.     

On Water: Brφnsted Acidic Ionic Liquid[(CH2)4SO3HMIM][HSO4]Catalysed Synthesis of Oxindoles Derivatives

Some oxindoles derivatives are synthesized from the condensation of indoles with isatins in the presence of green and recycable catalyst [(CH₂)₄SO₃HMIM][HSO₄] in water at room temperature.     

Dyadic Green’s function of a PEMC cylinder

The dyadic Green’s function of a PEMC cylinder is derived with the aid of the principle of scattering superposition and Ohm–Rayleigh method. The PEMC boundary conditions are presented in dyadic form and it shows that how the impedance parameter of PEMC and cross-polarized fields appear in the Green’s function. The asymptotic expansions of the dyadic function is calculated in order to attain a closed form for the electrical field.     

High‐Selective Tramadol Sensor Based on Modified Molecularly Imprinted Polymer?Carbon Paste Electrode with Multiwalled Carbon Nanotubes

We report here a novel carbon paste electrode (CPE) which is able to quantitatively sense tramadol under physiological conditions without sample preparation step. The selectivity of CPE is modified by applying molecularly imprinted polymer (MIP) technology. Multiwalled carbon nanotubes (MWCNTs) are incorporated in the structure of CPE to improve the conductivity and the ion‐to‐electron transduction. The electrode shows a wide dynamic linear range for tramadol from 10^?7 to 10^?3 M. The observed limit of detection and % RSD are 5×10^?7 M and 1.8 %, respectively. Finally, the proposed method is applied to determine tramadol in urine and medicinal tablets.