Synthesis of novel tricyclic and tetracyclic sultone scaffolds via intramolecular 1,3-dipolar cycloaddition reactions

The initially prepared 2-formylphenyl-(E)-2-phenylethenesulfonates from the condensation of (E)-2-phenylethenesulfonyl chloride with 2-hydroxybenzaldehyde derivatives underwent intramolecular [3+2] cycloaddition with methyl or phenylhydroxylamine, sarcosine, and l-proline, affording the corresponding novel isoxazolidine, pyrrolidine and pyrrolizidine-annulated γ,δ-benzo-δ-sultones, respectively, in good yields. Unambiguous assignment of the molecular structures was carried out by single-crystal X-ray diffraction.     

An efficient FeCl3/SiO2 NPs as a reusable heterogeneous catalyzed five-component reactions of tetrahydropyridines under mild conditions

A convenient, simple, and multicomponent coupling strategy has been developed for the synthesis of highly functionalized tetrahydropyridines using FeCl₃/SiO₂ NPs as catalyst. This method demonstrated five-component coupling reactions of 1,3-dicarbonyl compounds, aromatic aldehydes and amines without an inert atmosphere. Atom economy, good yields, environmentally benign, and mild reaction conditions are some of the important features of this protocol. Notably, this catalyst could be recycled and reused for several times without noticeably decreasing the catalytic activity.     

Palladium‐anchored multidentate SBA‐15/di‐urea nanoreactor: A highly active catalyst for Suzuki coupling reaction

Modification of mesoporous silica was carried out by reaction of SBA‐15 with di‐urea‐based ligand. Next, with the help of this ligand, palladium ions were anchored within the multidentate SBA‐15/di‐urea pore channels with high dispersion. The SBA‐15/di‐urea/Pd catalyst was characterized using various techniques. Theoretical calculations indicated that each palladium ion was strongly interacted with one nitrogen and two oxygen atoms from the multidentate di‐urea ligand located in SBA‐15 channels and these interactions remained during the catalytic cycle. These results are in good agreement with those of hot filtration test: the palladium ions have very high stability against leaching from the SBA‐15/di‐urea support. The catalytic performance of SBA‐15/di‐urea/Pd nanostructure was examined for the Suzuki coupling reaction of phenylboronic acid and electronically diverse aryl halides under mild conditions with a minimal amount of Pd (0.26 mol%). Compared to previous reports, this protocol afforded some advantages such as short reaction times, high yields of products, catalyst stability without leaching, easy catalyst recovery and preservation of catalytic activity for at least six successive runs.     

Polyelectrolyte Nanocomposite Membranes Using Surface Modified Nanosilica for Fuel Cell Applications

The preparation and characterization of a new type of nanocomposite polyelectrolyte membrane (PEM), based on Nafion® (E. I. du Pont de Nemours and Co., Ltd., for its copolymer of tetrafluoroethylene and perfluorinated vinyl ether) and sulfonic acid (-SO₃H) or phosphotungstic acid (PWA) modified nanosilica (Si-SO₃H or Si-PWA, respectively), for direct methanol fuel cell (DMFC) applications are described. Physical characteristics of these manufactured nanocomposite membranes were investigated by scanning electron microscopy (SEM), water uptake, methanol permeability and ion exchange capacity, as well as proton conductivity. The Nafion®/Si-PWA and Nafion®/Si-SO₃H membranes showed higher proton conductivity, lower methanol permeability and, as a consequence, a higher selectivity parameter, in comparison to the neat Nafion® or Nafion®/pristine nanosilica membranes. The obtained results indicated that both the Nafion®/Si-PWA and Nafion®/Si-SO₃H membranes could be utilized as promising polyelectrolyte membranes for direct methanol fuel cell applications.     

Erratum to: “The Influence of Solvent on the Structural Properties of trans-(NHC)PtI2Py Complex: A Platinum-Based Anticancer Drug” [Russian Journal of Physical Chemistry A92, 1219 (2018)]

Russian Journal of Physical Chemistry A - The name of the first author should read Tehereh Sadigh Vishkaee.     

Polymer ferroelectret based on polypropylene foam: piezoelectric properties prediction using dynamic mechanical analysis

Thin polypropylene (PP) foam films were produced by continuous extrusion using supercritical nitrogen (N₂) and then charged via corona discharge. The samples were characterized by dynamic mechanical analysis as a simple method to predict the piezoelectric properties of the cellular PP obtained. The results were then related to morphological analysis based on scanning electron microscopy and mechanical properties in tension. The results showed that the presence of a nucleating agent (CaCO₃) substantially improved the morphology (in terms of cell size and cell density) of the produced foam. Also, an optimization of the extrusion (screw design, temperature profile, blowing agent, and nucleating agent content) and post‐extrusion (calendering temperature and speed) conditions led to the development of a stretched eye‐like cellular structure with uniform cell size distribution. This morphology produced higher storage and loss moduli in the machine (longitudinal) direction than for the transverse direction, as well as higher piezoelectric properties. The morphological and mechanical results showed that higher cell aspect ratio led to lower Young's modulus, which is suitable to achieve higher piezoelectric properties. Finally, the best quasi‐static piezoelectric d₃₃ coefficient was 550 pC/N for a cellular PP ferroelectret having a uniform eye‐like cellular structure using N₂ as the ionizing gas inside the cells, while the highest value was only 250 pC/N when air was used. Hence, the value of d₃₃ can be improved by more than 100% just by replacing air with N₂ as the ionizing gas. Copyright © 2016 John Wiley & Sons, Ltd.     

Cis-dioxo-Mo(VI) salophen complex supported on Fe<Subscript>3</Subscript>O<Subscript>4</Subscript>@SiO<Subscript>2</Subscript> nanoparticles as an efficient magnetically separable and reusable nanocatalyst for selective epoxidation of olefins

In this work, paramagnetic Fe₃O₄/SiO₂ nanoparticles were synthesized, characterized and functionalized with dioxo-Mo(VI) tetradentate Schiff base complex and characterized using IR spectroscopy, X-ray powder diffraction spectroscopy, scanning electron microscopy, transmission electron microscopy, vibrating sample magnetometry, diffuse reflectance spectroscopy and atomic absorption spectroscopy. Catalyst was used for the selective epoxidation of cyclooctene, cyclohexene, styrene, indene, α-pinene, 1-hepten, 1-octene, 1-dodecen and trans-stilbene using tert-butyl hydroperoxide as oxidant in 1,2-dichloroethane. This catalyst is efficient for oxidation of cyclooctene with a 100% selectivity for epoxidation with 100% conversion in 1 h. After the reaction, the magnetic nanocatalyst was easily separated by simply applying an external magnetic field and was used at least five successive times without significant decrease in conversion.

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