Simple,rapid, and clean condensation of sulfonamide and maleic anhydride derivatives: Synthesis of novel 1H- Pyrrole-2,5-diones under heterogeneous conditions

H₆P₂W₁₈O₆₂ is used as an efficient catalyst for the synthesis of novel N-substituted sulfonyl maleimides (1H-Pyrrole-2,5-diones) via the condensation of sulfonamide and maleic anhydride derivatives. The Dawson heteropolyacid was used with a catalytic amount of 2 mmol% in acetonitrile at reflux. The reuse of H₆P₂W₁₈O₆₂ as heterogeneous catalyst several times without decrease in their activity, short reaction times, easy isolation of desired products with good to excellent yields shows the advantages of this novel methodology.     

An efficient green synthesis of new benzothiazoles containing sulfonamide or cyclic imide moieties

An efficient and convenient protocol for the one-pot synthesis of new benzothiazoles bearing sulfonamide or cyclic imide moieties using Cesium salt of Wells-Dawson heteropolyacid (Cs₅HP₂W₁₈O₆₂) as solid catalyst and water as solvent under ultrasound irradiation was reported. The reaction speed was remarkably catalyzed with the aid of ultrasound irradiation. Moreover, this approach prepares multiple other benefits such as operational ease, higher yields, and energy performance.     

Quantum chemical investigations on hydrogen bonding interactions established in the inclusion complex β-cyclodextrin/benzocaine through the DFT,AIM and NBO approaches

Structure and stability of an inclusion complex formed by Benzocaine (BZC) and β-cyclodextrin (β-CD) were investigated computationally using different levels of theory. The conformational research based on PM6 method allowed reach two minimum-energy structures: model A and model B. The lowest conformers have been exposed to fully geometry optimization employing four DFT functionals: B3LYP, CAM-B3LYP, M05-2X and M06-2X. The performed DFT calculations have identified the model B, in which the amino group is located at the primary face of β-CD, as the most stable complex by an amount up to ?40 kcal/mol. Further, the greater stabilization of model B in respect to model A, has been ascertained through AIM and NBO analyses which clarified the main hydrogen bonds HBs interactions governing the reactivity of BZC inside the hydrophobic cavity of β-CD. Finally, the estimated isotropic ¹H nuclear magnetic shielding constants generated from the gauge-including-atomic-orbital calculation have been analyzed and then compared with the available experimental data.     

Suspension Polymerization of Vinyl Chloride with Programmed Temperature: Morphological Characteristics and Thermal Stability of Polyvinyl Chloride)

Polyvinyl chloride) obtained by intermittent polymerization in suspension with temperature programming, has been characterized from the point of view of morphological properties and of thermal stability. The data have been compared with the values of the morphological characteristics and thermal stability for the PVC samples obtained under identical polymerization conditions, but at constant temperature. The polyvinyl chloride) obtained by polymerization with temperature programming has the same properties as the polyvinyl chloride) obtained by simple polymerization at constant temperature, with an identical average molecular weight. However, the former polymer shows improved thermal stability, as well as a decrease in the volumetric properties.     

Cooperativity of copper and molybdenum centers in polyoxometalate-based electrocatalysts: cyclic voltammetry, EQCM, and AFM characterization

Electrochemical behaviors of selected Dawson-type polytungstates including 2-K10[P2W15Mo2O61box] where the symbol [box] designates a vacant site, alpha2-K7[Fe(OH2)P2W15Mo2O61], alpha2-K8[Cu(OH2)P2W15Mo2O61], alpha1- and alpha2-K8[Cu(OH2)P2W17O61], alpha2-K8[Cu(OH2)P2W13Mo4O61], and alpha2-K8[Cu(OH2)P2W12Mo5O61] were investigated by cyclic voltammetry (CV) coupled with the electrochemical quartz microbalance (EQCM), and the results were completed by atomic force microscopy (AFM) observations of the electrodeposited films. The electrocatalytic abilities of these polyoxometalates (POMs) in the reduction of dioxygen, hydrogen peroxide, and NOx were also assessed by CV and EQCM. It turns out that the remarkable electrocatalysis obtained at the reduction potential of Mo centers within alpha2-K8[Cu(OH2)P2W15Mo2O61], but in a domain where Cu2+ is not deposited, benefits from the assistance of the copper center because such catalysis could not be observed in the absence of Cu2+. EQCM confirms that no copper deposition occurs under the experimental conditions used. Analogous behaviors are encountered in the electrocatalytic reduction of nitrite where assistance by the presence of the Cu2+ center induced the observation of catalysis at the potential location of Mo centers. Finally, the reduction of nitrate is triggered by electrodeposited copper but was remarkably favored by the presence of molybdenum atoms within these polyoxometalates (POMs). All of the results converge to indicate a cooperative effect between the Mo and Cu centers within these POMs. The various results suggest that copper deposition from these POMs should give morphologically different surfaces. AFM studies confirm this expectation, and the observed morphologies and sizes of particles were rationalized by taking into account the role of the POM skeleton and its atomic composition in the electrodeposition process.