Surprising Formation of Chlorinated Butenolides from Dialkyl Acetylenedicarboxylates and Hexachloro­acetone in the Presence of Triphenyl Phosphite

Triphenyl phosphite reacts smoothly with dialkyl acetylenedicarboxylates and hexachloroacetone to produce alkyl 2‐(dichloromethylene)‐2,5‐dihydro‐5‐oxo‐4‐(trichloromethyl)furan‐3‐carboxylates in good yields.     

Efficient functionalizations of a pyranosido-pyrimidine scaffold

Efficient reaction conditions have been developed to prepare highly functionalized chiral pyranosido-pyrimidine by regioselective alkylation of the pyranoside ring and palladium-catalyzed cross-coupling reaction on the pyrimidine ring under microwave activation. Such scaffold contains three different functions suitable for selective derivatization and could find applications in the design of peptidomimetics.     

Reaction of benzoyl chlorides with Huisgen's zwitterion: synthesis of functionalized 2,5-dihydro-1H-pyrroles and tetrasubstituted furans

The 1:1 intermediate generated by the addition of alkyl(aryl) isocyanides to dimethyl acetylenedicarboxylate is trapped by benzoyl chloride to yield functionalized 2,5-dihydro-1H-pyrroles. The presence of electron-withdrawing groups at the para position of benzoyl chloride leads to tetrasubstituted furans. The structures of these products were confirmed by single-crystal X-ray diffraction studies.     

Reaction between benzoyl isothiocyanate and 2,6-dimethylphenyl isocyanide: synthesis of a sterically congested ten-membered ring containing the S–S–S moiety

Abstract  

2,6-Dimethylphenyl isocyanide reacts with benzoyl isothiocyanate in a clean one-pot reaction to afford a sterically congested ten-membered ring containing the S–S–S moiety in nearly quantitative yield. Dynamic effects are observed in the ¹H nuclear magnetic resonance (NMR) spectrum of this compound for the restricted rotation around two of the Ar–N single bonds.     

Electrical conductivity studies on some dibenzoylmethane arylhydrazones (DBMAH)

Electrical conductivity of some dibenzoylmethane arylhydrazones (DBMAH) were measured during heating and reheating runs. The observed variation of the conductance of the polycrystalline sample during thermal agitation was found to depend on the ordering and disordering of molecules which in turn cause the lattice dipole to distort. A semiconducting behavior was detected for these systems as it was deduced from their conductance values (1.7 × 10⁻⁶ − 8.25 × 10⁻⁷ ohm⁻¹ cm⁻¹). The presence of substituents affects markedly the measured electrical conductivity and calculated activation energy values.     

Self-assembly of CuSO4 nanoparticles and bending multi-wall carbon nanotubes on few-layer graphene surfaces

When a colloidal suspension is allowed to wet a suitable substrate, various patterns emerge that can be varied from isolated island-like structures to fractal patterns. In this work we investigate the patterns arising from the interplay of colloidal copper sulfate suspensions containing carbon nanotubes with few-layer graphene substrates. The compositions of the thin film samples were investigated using X-ray photoelectron spectroscopy, surface topography and the nanostructure of the thin films were probed with atomic force microscope and transmission electron microscope respectively. The colloidal suspensions were characterized using contact angle and viscosity measurements. The colloidal suspensions when dip coated on few-layer graphene substrates exhibited fractal like morphology with the aggregation of copper sulfate crystallites to hexagonal platelets. This aggregation is explained invoking the depletion attraction theory. The various patterns observed experimentally were reproduced using a Monte Carlo simulation.     

Convergence analysis of the Wolf method for Coulombic interactions

A rigorous proof for convergence of the Wolf method (Wolf et al., 1999 [9]) for calculating electrostatic energy of a periodic lattice is presented. In particular, we show that for an arbitrary lattice of unit cells, the lattice sum obtained via Wolf method converges to the one obtained via Ewald method.