High-Fidelity,Narcissistic Self-Sorting in the Synthesis of Organometallic Assemblies from Poly-NHC Ligands

Highly selective, narcissistic self-sorting has been observed in the one-pot synthesis of three organometallic molecular cylinders of type [M₃{L-(NHC)₃}₂](PF₆)₃ (M=Ag⁺, Au⁺; L=1,3,5-benzene, triphenylamine, or 1,3,5-triphenylbenzene) from L-(NHC)₃ and silver(I) or gold(I) ions. The molecular cylinders contain only one type of tris-NHC ligand with no crossover products detectable. Transmetalation of the tris-NHC ligands from Ag⁺ to Au⁺ in a one-pot reaction with retention of the supramolecular structures is also demonstrated. High-fidelity self-sorting was also observed in the one-pot reaction of benzene-bridged tris-NHC and tetrakis-NHC ligands with Ag₂O. This study for the first time extends narcissistic self-sorting in metal–ligand interactions from Werner-type complexes to organometallic derivatives.     

A polymer regulator of enzyme activity

The reaction of the amino group of α-chymotrypsin with poly(N,N-diethylacrylamides) bearing terminal carboxyl groups which have the degree of polymerization ranging from 30 to 180 and which possess an LCST of 34–29°C affords polymer derivatives of the enzyme. It is found that, upon an increase in the temperature of the aqueous solution of the resulting derivatives to 40°C, the derivative with a degree of polymerization of 180 precipitates at 34°C, while the derivatives with a degree of polymerization of 30–80 remain in solution. The activity of α-chymotrypsin as a part of the derivatives with a degree of polymerization of 30 does not change with increasing temperature, whereas the activity of the enzyme as a part of the derivatives with degrees of polymerization of 60 and 80 decays almost to zero near the LCST of the initial polymers. Such a change in the enzyme activity is reversible (the activity fully recovers with a decrease in temperature).     

Reaction of <Emphasis Type="Italic">N</Emphasis>-chloroamines with carbanions derived from ethyl acetoacetate and diethyl malonate

Carbanions derived from ethyl 3-oxobutanoate and diethyl malonate reacted with an equimolar amount of N-chloro-N-ethylethanamine, N-chloromorpholine, or N-chloropiperidine to give diethyl 2,3-diacetylbutanedioate and tetraethyl ethane-1,1,2,2-tetracarboxylate in 68–83% yield. The possibility of heterocoupling of ethyl 3-oxobutanoate and diethyl malonate carbanions by the action of N-chloro-N-ethylethanamine and the effect of the molar reactant ratio on the selectivity of oxidative homo- and heterocoupling were studied.     

Synthesis and study of complexes of copper(II) and mercury(II) with triaryl- and diarylalkylarsine oxides

Russian Journal of General Chemistry - The interaction of copper(II) and mercury(II) nitrates with triaryl- and diarylalkylarsine oxides has been studied. The reactions in aqueous-alcoholic...     

Preparation and optical properties of composite materials based on polybenzimidazole and silver nanoparticles

Rigid-chain heat resistant polymers (with poly-2,2'-p-oxydiphenylene-5,5′-bisbenzimidazole as example) were impregnated for the first time with a silver-containing precursor in formic acid and in supercritical carbon dioxide. A procedure allowing the precursor reduction to silver nanoparticles both throughout the volume by thermal annealing of the films in the temperature interval 100–150°С and in the targeted mode using lasers operating at 405 and 532 nm was developed. It opens prospects for developing a process for production of heatresistant optical gratings and light guides. The reduces nanoparticles and their agglomerates have the size in the interval 50–200 nm and give a plasmon band in the range 450–460 nm.     

Degradation of physicomechanical properties of epoxy nanocomposites with carbon nanotubes upon heat and humidity aging

The dependence of the physicomechanical properties of epoxy nanocomposites subjected to heat and humidity aging on the type of covalently functionalized carbon nanotubes and on the uniformity of their distribution in the epoxy matrix was studied. Two types of carbon nanotubes were used: those modified with carboxy and amide groups. The elastic modulus, bending deflection, and ultimate bending strength for the initial epoxy nanocomposites with carbon nanotubes and for those subjected to heat and humidity aging were determined. The epoxy binders modified with carboxylated carbon nanotubes are more resistant to the action of aging factors. The presence of aggregates of carboxylated carbon nanotubes in the epoxy matrix positively influences the preservation of physicomechanical properties of the composite subjected to heat and humidity aging. Microscopic examination revealed structural features of the epoxy nanocomposite and their effect on the resistance of the composite to the heat and humidity aging.     

Distribution of Zinc Oxide Nanocrystals in a Polymer Film

The structure of polymer films modified with zinc oxide nanocrystals was studied by the optical absorption and small-angle X-ray scattering methods. Small-angle X-ray scattering allows determination of the nanoparticle size distribution function, which is the decisive factor in predicting the optical properties of heterophase materials, including filled polymer films. The optical absorption spectrum of an acrylate polymer film doped with 1.6 wt % zinc oxide nanocrystals approaches the ideal absorber spectrum, which allows this material to be recommended for use as a protective color filter.     

Deposition of protective-decorative coatings onto aluminum alloys

Technique for deposition of a nickel coating onto various aluminum alloys was developed. This coating can be used both independently and as a sublayer under multilayer coatings and, in particular, under those of nickel, tin–bismuth, lustrous nickel, and lustrous chromium. The technique includes anodization, chemical treatment, and electrodeposition of nickel in a special solution. The working modes of the anodization electrolyte were chosen and the necessity for a preliminary chemical treatment of the oxide film being formed was substantiated. A composition of the acid electrolyte for the subsequent nickel plating was developed with buffer and improving additives. The thus deposited electroplated nickel coatings exhibit a high adhesion to the aluminum base without additional thermal treatment. This makes it possible not only to reduce the technological time for deposition of the subsequent multilayer coatings, but also to fully automate the whole process.     

<Emphasis Type="Italic">peri</Emphasis>-cyclization of 11-aroylmethyl-2,3,4,5-tetrahydro[1,3]-diazepinobenzimidazoles into 2-aryl-3,4,5,6-tetrahydro-2a,6a,10b-triazabenzo[<Emphasis Type="Italic">a</Emphasis>]cyclopenta[<Emphasis Type="Italic">cd</Emphasis>]azulenium bromides

11-Aroylmethyl-2,3,4,5-tetrahydro[1,3]diazepinobenzimidazoles at heating in conc. HBr suffer a peri-cyclization with the closure of an additional imidazole ring involving the carbonyl group of ketone and the nitrogen atom of the diazepine ring affording previously unknown 2-aryl-3,4,5,6-tetrahydro-2a,6a,10btriazabenzo[a]cyclopenta[cd]azulenium bromides.     

New chalcones containing carbazole and 3,4-ethylenedioxythiophene fragments

Russian Journal of Organic Chemistry - Acylation of 9-(2-ethylhexyl)carbazole with acetyl bromide in the presence of tin(IV) chloride gave 3-acetyl- and 3,6-diacetyl-9-(2-ethylhexyl)carbazoles...