Electrical and magnetic properties of nanodiamond and pyrocarbon composites

The electrical and magnetic properties of the nanodiamond composites comprising nanodiamond, pyrolytic carbon, and nanosized pores were studied. The composites are p-type semiconductors and their resistance decreases by 12 orders of magnitude as the pyrocarbon-to-diamond ratio γ increases from 0 to 80 wt %. Evidence for paramagnetic properties of the nanodiamond composites was obtained. The observed properties are explained by increased concentration of surface Tamm states. The paramagnetic properties are explained in terms of the electron spins localized on the nanodiamond surface in the composite.     

Oxidation and reductive bromination of Bis(4-tert-butylphenyl)aminoxyl

One-electron oxidation of bis(4-tert-butylphenyl)aminoxyl with antimony pentachloride and bromine leads to the formation of oxoammonium salts with anions SbCl ₆ ^? and Br ₃ ^? respectively. The salt with the Br ₃ ^? anion converted at heating into a mixture of bromodiphenylamines which formed also from the aminoxyl as a result of previously unknown reaction of three-electron reductive bromination. The mechanisms of these reactions were assumed.     

Benzoid-quinoid tautomerism of Schiff bases and their structural analogs: LV. Crown-containing N-phenylimines derived from ortho-hydroxycarbaldehydes of the coumarin series

Schiff bases were synthesized from 3-hydroxy-6-oxo-6H-benzo[c]chromene-4-carbaldehyde, 5-hydroxy-4,7-dimethyl-2-oxo-2H-chromene-6-carbaldehyde, 6,7-dihydroxy-4-methyl-2-oxo-2H-chromene-8-carbaldehyde, 5,7-dihydroxy-4-methyl-2-oxo-2H-chromene-6,8-dicarbaldehyde, and 5-hydroxy-4,7-dimethyl-2-oxo-2H-chromene-6,8-dicarbaldehyde and (¹⁵N)aniline or aminobenzo-15-crown-5 (2,3,5,6,8,9,11,12-octahydrobenzo[b][1,4,7,10,13]pentaoxacyclopentadecin-15-amine), and tautomeric equilibrium between the hydroxy enimino and keto enamino forms of the 4- and 8-iminomethyl derivatives in solution was revealed by 1H NMR and electronic spectroscopy. Addition of alkaline earth cations to their solutions in acetonitrile displaced the tautomeric equilibrium toward the hydroxy enimino structure due to complex formation with the crown ether fragment.     

Synthesis and fungicidal activity of the quaternary ammonium salts of the 1,3,7-substituted dibenzothiophene-5,5-diones

A series of novel double quaternary ammonium salts based on 5,5-dioxo-5H-dibenzo[b,d]thiophene has been prepared via quaternization of the corresponding 3,7-bis(chloromethyl)dibenzothiophene-5,5-diones with various N,N-dimethylalkylamines. Pronounced fungicidal activity of the C¹-substituted quaternary ammonium salts has been observed.     

Reaction of unsymmetrical α,β-unsaturated ketones with thiobarbituric acid

Carbocyclization of unsymmetrical 1,5-diarylpenta-1,4-dien-3-ones with thiobarbituric acid afforded previously unknown 7,11-diaryl-3-thioxo-2,4-diazaspiro[5.5]undecane-1,5,9-triones with high regio- and stereoselectivity. The same spiro compounds were also synthesized by three-component condensation of thiobarbituric acid with the corresponding aromatic aldehydes and 4-arylbut-3-en-2-ones.     

Synthesis of 3-hetaryl-1,5,3-dithiazepanes and 3-hetaryl-1,5,3-dithiazocanes in the presence of catalysts based on transition metals

Efficient procedure was developed for 3-hetaryl-1,5,3-dithiazepanes and 3-hetaryl-1,5,3-dithiazocanes preparation from hetarylamines, N,N,N′,N′-tetramethylmethanediamine, and α,ω-alkanedithiols (ethane-1,2-dithiol, propane-1,3-dithiol), and also by the reaction of the latter with N,N-bis(methoxymethyl)hetarylamines in the presence of catalytic quantities of transition metals salts.     

Electrochemical properties of Ebonex®/Pt anodes

The electrochemical behavior of platinized Ebonex® was studied. The electrochemical and semiconductor properties of electrodes can be varied within wide limits by thermal treatment of Ebonex®/Pt, which selectively affects the electrocatalytic activity of anodes in the oxygen evolution reaction. The reduction peak of platinum oxides on the cyclic voltammetry (CV) curves can be used as a correlation parameter when evaluating the electrocatalytic activity of Ebonex®/Pt electrodes in the oxygen evolution reaction.     

Conducting properties of a gel ionite modified with zirconium hydrophosphate nanoparticles

The organo-inorganic composites based on a strongly acid gel resin including zirconium hydro-phosphate nanoparticles and their aggregates were studied by impedance spectroscopy, electron microscopy, and standard contact porosimetry. The porous structure of the polymer was transformed under the action of the inorganic filler. The nanoparticles in the transport pores provided a three- to fivefold increase in the electric conductivity of the nanocomposites compared with the conductivity of the nonmodified ionite and a decrease in the percolation threshold. The nanocomposite ionites demonstrated stability against the accumulation of organic substances during electrodeionization to extract Na⁺ from low-concentrated solutions.     

A new method for the synthesis of sulfonated polynaphthylimides

A new method for the synthesis of sulfonated polynaphthylimides has been developed on the basis of the postsulfonation of high-molecular-mass polynaphthylimides with a sulfuric acid-oleum mixture. Sulfonated polymers of this type have been obtained from the polycondensation products of 5-phenylthiophenylene-1,3-diamine with dianhydrides of 1,4,5,8-naphthalenetetracarboxylic acid and 4,4′-(1,4-phenylenedicarbonyl)-bis-naphthalene-1,8-dicarboxylic acid. It has been shown that hydrogen peroxide oxidation of sulfide bridge groups of these polymers in an acidic medium yields high-molecular-mass compounds that contain sulfonic bridge fragments and, therefore, have increased thermal stabilities and enhanced proton conductivities.