Bulk and supported tungstophosphoric acid as friendly,efficient, recyclable catalysts for the synthesis of bis‐indolylmethanes under solvent‐free conditions

The treatment of indole with structurally diverse aldehydes in the presence of catalytic amount of inorganic‐supported polyoxometalates, heterogeneous, reusable and efficient catalysts at room temperature gave the corresponding bis‐indolylmethanes in excellent yields and shorter reaction times under solvent‐free conditions. The catalyst can be reused for several times, but it will be less active. © 2009 Wiley Periodicals, Inc. Heteroatom Chem 20:325–331, 2009; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/hc.20554     

On Anti-Hermitian Metric Connections Preserving a Bicomplex Structure

We give a characterization of bicomplex-holomorphic anti-Hermitian manifolds by using pure metric connection     

Regioselective bromination and iodination of aromatic substrates promoted by trans-3,5-dihydroperoxy-3,5-dimethyl-1,2-dioxolane

Selective and efficient bromination and iodination of aromatic compounds by ammonium bromide and ammonium iodide, respectively, under promotion of trans-3,5-dihydroperoxy-3,5-dimethyl-1,2-dioxolane have been explored. Mild reaction conditions, high selectivity and yield, and high reaction rate are some of the major advantages of this synthetic method.     

Synthesis of gem-Dihydroperoxides from Ketones and Aldehydes Using Silica Sulfuric Acid as Heterogeneous Reusable Catalyst

Silica sulfuric acid (SSA) was found to efficiently catalyze the conversion of aldehydes and ketones directly into the corresponding gem-dihydroperoxides (DHPs) on treatment with aqueous 30% H₂O₂ at room temperature. Mild reaction conditions, good to excellent yields, short reaction times, low environmental impact, and recyclability of the catalyst are the main advantages of this synthetic method.     

Supercritical fluid extraction followed by supramolecular solvent microextraction as a fast and efficient preconcentration method for determination of polycyclic aromatic hydrocarbons in apple peels

In this work, reverse micelle‐based supramolecular solvent microextraction method coupled with supercritical fluid extraction and used for determining trace amounts of polycyclic aromatic hydrocarbons in apple peels. The extract was analyzed by high‐performance liquid chromatography equipped with a fluorescence detector. Coupling supramolecular solvent microextraction with supercritical fluid extraction method, resolve low preconcentration factor of supercritical fluid extraction method, improved limit of detection of polycyclic aromatic hydrocarbons and allow the use of supramolecular solvent microextraction in solid matrices. The effective parameters on the supramolecular solvent microextraction and supercritical fluid extraction efficiency were optimized using one variable at a time and face centered design methods, respectively. Under the optimum condition, the limits of detection and limits of quantifications were in the range of 0.34–1.27 and 1.03–3.82 µg/kg, respectively. Analysis of polycyclic aromatic hydrocarbons in apple peels showed that the supercritical fluid extraction/ supramolecular solvent microextraction method provide great potential for trace analysis of polycyclic aromatic hydrocarbons in fruit samples (RSDs < 7.7%).     

Ionic liquid promoted green synthesis of new pyridazino benzazepine derivatives: Evaluation of antioxidant activity

In this research, we investigated preparation of pyridazino benzazepine derivatives in high yields via the domino and one-pot reaction of isatoic anhydride, N-methylimidazole, alkyl bromides, activated acetylenic compounds, and hydrazine in ionic liquid as green media at 80°C. Also, antioxidation property of some prepared pyridazino benzazepines due to having pyridazin and benzazepine core is investigated by employing of trapping diphenyl-picrylhydrazine radical and ability of ferric reduction experiment. Our procedure has a few benefits relative to reported method such as good rate of reaction, product with high efficiency, and simple separation of product from mixture of reaction.     

Synthesis of magnetically modified mesoporous nanoparticles and their application in simultaneous determination of Pb(II), Cd(II) and Cu(II)

In this study, a novel adsorbent from a mesoporous family (MCM-41) coating with CoFe₂O₄ and piperazine was synthesized by a simple and easy route. Its application for simultaneous preconcentration of three heavy metals including lead, cadmium and copper in real samples followed by a flame atomic absorption spectroscopy was investigated. The central composite design was employed for investigating the most effective factors of pH, amount of adsorbent, the equilibrium time and their interactions. Under the optimum conditions, the detection limits for lead, cadmium and copper were 0.50, 0.30 and 0.25 μg L^?1, respectively, and the preconcentration factor (PF) was 33. The presented method was successfully employed for the simultaneous determination of the three mentioned heavy metals in real samples with recoveries of 90%–105%. The accuracy of the suggested methods was also investigated through spiking samples and a reasonable range for recoveries from 90.3% to 107% was acquired. The isotherm models and thermodynamic parameters have also been studied. The new adsorbent showed fast adsorption kinetics within 10 min and maximum Langmuir monolayer capacities of 238.09, 178.57 and 208.33 mg g^?1 for lead, cadmium and copper, respectively.