1,4-Addition of benzene to a dihydrocyclopent[a]indene diradical: synthesis and DFT study

Photochemical cyclization of compound 1, a homoenediyne (-CCC=CCH2CC-) bearing two ethynylanthracene chromophores, yields two isomeric dihydrocyclopent[a]indene ring systems, spiro-fused to the 9-position of a 9,10-dihydroanthracene moiety. Evidence of a photochemically initiated diradical cyclization pathway is proposed on the basis of (i) hydrogen abstraction from reaction with 1,4-cyclohexadiene (1,4-CHD) and (ii) the observation of 1,4-addition of benzene (solvent). The reaction was further analyzed by a complete density functional theory (DFT) study, using an unrestricted approach (UBLYP) with a 6-31G* basis set for the open-shell triplet states of the reactants, products, and diradical intermediates to model the photochemical nature of observed transformation. A mechanism detailing the observed cyclization/addition reaction is proposed.     

A Pauson-Khand-type reaction between alkynes and olefinic aldehydes catalyzed by rhodium/cobalt heterobimetallic nanoparticles: an olefinic aldehyde as an olefin and CO source

Co/Rh (Co:Rh = 2:2) heterobimetallic nanoparticles derived from Co(2)Rh(2)(CO)(12) react with alkynes and alpha,beta-unsaturated aldehydes such as acrolein, crotonaldehyde, and cinnamic aldehyde and release products resulting from [2 + 2 + 1]cycloaddition of alkyne, carbon monoxide, and alkene. alpha,beta-Unsaturated aldehydes act as a CO and alkene source. These reactions produce 2-substituted cyclopentenones.     

Photochemical and photocatalytic properties of zeolites containing titanium(iv) complexes and metallic palladium

An attempt has been made to create organized, highly efficient photocatalytic systems in the example of composite materials consisting of blocks of a metallocomplex photocatalyst and a dark-stage catalyst, assembled on a zeolite matrix. The spectral and photochemical properties of these systems have been investigated, and also their use in catalysis of hydrogen evolution from alcohol-water media. L. V. Pisarzhevskii Institute of Physical Chemistry, National Academy of Sciences of the Ukraine, 31 Nauka Prospect, Kiev 252039, Ukraine. Translated from Teoreticheskaya i éksperimental’naya Khimiya, Vol. 34, No. 2, pp. 103–108, March–April, 1998.     

Alkaline Decomposition of Cyclic Nitramines

Treatment of 1,3,5-trinitro-1,3,5-triazacyclohexane and 1,3,5,7-tetranitro-1,3,5,7-tetrazacyclo-octane with potassium hydroxide gives dipotassium salt of methylenedinitramine.__________Translated from Zhurnal Obshchei Khimii, Vol. 75, No. 1, 2005, pp. 130–132.Original Russian Text Copyright © 2005 by Il’yasov, Lobanova.     

Fabrication of nanocapsules with Au particles trapped inside carbon and silica nanoporous shells

Carbon capsules with hollow cores and mesoporous shells (HCMS) containing entrapped Au particles were prepared by template replication from solid core/mesoporous shell silica spheres with encapsulated Au particles. The resulting HCMS carbon capsules were then nanocast one step further to generate Au-trapping hollow core silica capsules with nanostructured shells.     

Transformations of epoxide derived from nopol over askanite-bentonite clay

Transformations of epoxide derived from nopol in the presence of natural askanite-bentonite clay were studied. The major products of the isomerization in the cold are diols possessing a p-menthane skeleton, which are readily converted into bicyclic ethers when the reaction is carried out at room temperature.Translated from Zhurnal Organicheskoi Khimii, Vol. 40, No. 10, 2004, pp. 1483–1487.Original Russian Text Copyright © 2004 by Ilina, Volcho, Korchagina, Salakhutdinov, Barkhash.     

Behavior of protein-like N-vinylcaprolactam and N-vinylimidazole copolymers in aqueous solutions

The free-radical copolymerization of N-vinylcaprolactam and N-vinylimidazole (at an initial comonomer ratio of 85: 15, mol/mol) initiated by a persulfate-tertiary amine redox system in 10% aqueous DMSO at 25 and 65°C (at temperatures below and above the temperature of phase separation in the reaction system, respectively) yielded macromolecular products that were subsequently separated into thermally precipitating and nonprecipitating fractions. Investigations of these fractions by capillary viscometry, static and dynamic laser light scattering, and high-sensitivity DSC showed that macromolecules of both types of copolymers are strongly associated in aqueous solutions. Upon heating of solutions of thermally nonprecipitating fractions, additional aggregation takes place and this phenomenon is accompanied by a decrease in the size of particles without loss in their solubility until at least 70°C is reached. As for the set of properties exhibited in aqueous solutions, the thermally nonprecipitating fraction of the copolymer synthesized at 65°C may be assigned to protein-like macromolecules.     

Effect of the nature of the metal oxide on selective transformation of methane under unsteady conditions in the absence of oxidant in the gaseous phase

The catalytic transformation of methane into higher hydrocarbons was studied under unsteady conditions on oxides of various metals (Pb, Fe, Nb, Ti, Cd, Mo, Mg, Zn, Zr, Bi, Mn), and also on Sr-, La-, Y-, and Mn-containing oxides of perovskite structure. It is shown that the effectiveness of the catalysts not only depends on their chemical composition, but also is determined to a considerable degree by the specific surface of the oxides. L. V. Pisarzhevskii Institute of Physical Chemistry, Academy of Sciences of Ukraine, 252039 Kiev, Prosp. Nauki, 31, Ukraine. Translated from Teoreticheskaya i éksperimental’naya Khimiya, Vol. 33, No. 2, pp. 91–95, March–April, 1997.     

Immobilized cobalt/rhodium heterobimetallic nanoparticle-catalyzed silylcarbocylization and carbonylative silylcarbocyclization of 1,6-enynes

Reaction of 1,6-enynes with a hydrosilane in the presence of immobilized cobalt/rhodium bimetallic nanoparticles gives 2-methyl-1-silylmethylidene-2-cyclopentanes in the absence of carbon monoxide and 2-formylmethyl-1-silylmethylidene-2-cyclopentanes under 1 atm of carbon monoxide, respectively. [reaction: see text]     

Cavitands bearing four fluorophores

The synthesis of novel cavitands containing four fluorophores [tert-butoxycarbonyl protected 2,2′-bis(furyl)benzidine (t-BOC FurylBz) or 5,5′-bis(4-aminophenyl)-2,2′-bifuryl (t-BOC PFDA)] and ionophoric functional groups on the upper rim is reported. The cavitands bearing the four fluorophores emit blue light photoluminescence. In particular, the cavitand containing PFDA moieties exhibits a high photoluminescence quantum yield.