Palladium–Polypyrrole Nanoparticles-Catalyzed Sonogashira Coupling

Palladium nanoparticles were encapsulated into polypyrrole globules via one-step one-pot redox reaction between tetraamminepal- ladium(ii) dichloride and pyrrole in water. Such a material is an active catalyst for the Sonogashira coupling of iodo- and bromo- arenes.     

Oligomerization of 3,5-dimethyl benzyl alcohol promoted by clay: experimental and theoretical study

Linear oligomerization of 3,5-dimethyl benzyl alcohol is induced by a montmorillonite clay (Tonsil Optimum Extra), producing 1,3,5,7-tetramethyl-9,10-dihydro-anthracene, which, by loss of protons results in the product 1,3,5,7-tetramethylanthracene. It was also found that the compounds 4-(3′,5′-dimethylbenzyl)-1,3,5,7-tetramethyl-9,10-dihydroanthracece and 4-(3′,5′-dimethylbenzyl)-1,3,5,7-tetra-methylanthracene were formed from 1,3,5,7-tetramethyl-9,10-dihydroanthracene. 1,3,5,7-Tetramethylanthryl radical cation was formed from 1,3,5,7-tetramethyl-9,10-dihydroanthracene; it was characterized by Electronic Paramagnetic Resonance (EPR). On the other hand, a theoretical analysis was performed, allowing the rationalization of the observed products and some of the key reaction steps.     

Synthesis and study of new indoline spiropyran and its derivative with α-lipoic acid exhibiting low cytotoxicity

Russian Chemical Bulletin - New indoline spiropyran was synthesized by the cyclocondensation of 5-chlorine-substituted Fischer base with 2,7-dihydroxy-1-naphthaldehyde. This spiropyran was used to...     

Kinetics and Mechanism of the Pudovik Reaction in the Series of Shiff Bases. Addition of Dialkylphosphites to Substituted N-Alkyl(Aryl)Benzylideneamines

Abstract

Kinetic and preparative investigation of the reaction of addition of dialkylphosphites to a serias of Shiff bases of the type Ar-CH?N-R (R = Alk, Ar₃) (1) is investigated. On the basis of kinetic data obtained (Table) the nucleophilic addition mechanism is suggested.     

Stacking of main chain-crown ether polymers in thin films

Thin films (9-70 nm) of a series of polymers containing in the main chain dibenzo-18-crown-6 ether unit (DB18C6) linked to an aliphatic spacer of different length (10C and 14C) and nature have been prepared, from chloroform solutions, by spin coating on a silicon substrate. The quality and homogeneity of the polymer coatings was revealed by their reflectivity spectra and atomic force microscopy (AFM). The grazing incidence small-angle X-ray scattering (GISAXS) patterns show an out-of-plane structure correlation (interference maximum near the horizon) of scale size related to the polymer repeating unit length. Above this Bragg reflection, the shape of the scattering observed, in the GISAXS pattern, reveals an orientation of the stacked molecular columns in the coated polymer. A thermal treatment of the samples improves the nanostructure by increasing the lamellar coherence size (in y-direction) as well as the vertical orientation of the molecular columns.     

Formation of nanostructured carbon films in gas-discharge plasmas

Deposition of carbon materials from methane-hydrogen gas mixtures in a DC gas discharge is investigated. Parameters ensuring stable discharge conditions and synthesis of diamond and graphite-like films are determined. Optical emission spectroscopy is used to analyze the composition of the activated gas phase in the course of carbon film deposition. Synthesis of graphite-like carbon nanotubes and nanocrystallites is shown to correlate with the presence of C₂ dimers in the plasma. A noncatalytic mechanism of synthesis of nanostructured graphite in a carbon-containing gas phase is proposed.     

Spontaneous Ring‐Opening Polymerization of Macrocyclic Aromatic Thioether Ketones under Transient High‐Temperature Conditions

Summary: Spontaneous ring‐opening polymerization of macrocyclic aromatic thioether ketones [ 1,4‐SC₆H₄COC₆H₄ ]_n (n = 3 and 4), in which the thioether linkages are para to the ketone, occurs during rapid, transient heating to 480 °C, to afford a soluble, semi‐crystalline poly(thioether ketone) of high molar mass (η_inh > 1.0 dL · g⁻¹). Corresponding macrocyclic ether ketones, and a macrocyclic thioether ether ketone in which the thioether linkage is para to the ether rather than to the ketone, show no evidence of polymerization under analogous conditions.

The uncatalysed ring‐opening polymerization of macrocycle 1 , within the pores of an alumina microfiltration membrane, leads to formation of polymer 3 with the microstructure shown in the above scanning electron micrograph.     

DFT and local MP2 study of switching process in a pH controllable molecular “shuttle”

A pH controllable molecular “shuttle,” comprising of dibenzo 24 crown‐8 (DB24C8) macroring bound to a “finger” molecule possessing two different recognition sites has been studied at the density functional theory (DFT) and Møller‐Plesset second‐order (MP2) levels of theory. The calculation confirmed experimental results that translational conformer with DB24C8 located around NH station has the lowest energy, while the conformer with DB24C8 located around NH station shows the highest energy. It has been found that Bpym2+ unit consists of two “substations” separated by an energy barrier of 3–17 kcal/mol depending on the state of the NH–NH station. The translational conformers are stabilized by NH…O, ⁺NH…O, ⁺NCH…OH‐bonds, and π–π stacking with different contributions, depending on the conformer type. © 2006 Wiley Periodicals, Inc. Int J Quantum Chem 2007