PHOTO-OXIDATION OF LYSOZYME IN THE PRESENCE OF METHYLENE BLUE: A PROBABLE MECHANISM

Abstract— In order to elucidate the mechanism of the photo-oxidation of lysozyme sensitized by methylene blue this enzyme was oxidized by singlet oxygen generated by a high–frequency discharge in gaseous oxygen. The action of singlet oxygen on lysozyme gives products identical with those obtained upon dye-sensitized oxidation with respect to their affinity to chitin, their amino acid content, their UV spectra and their enzymic activity. It is concluded that photo-oxidation of lysozyme in the presence of methylene blue proceeds according to the singlet-oxygen mechanism.     

TMSCl-promoted isocyanide-based MCR of ethylenediamines: an efficient assembling of 2-aminopyrazine core

New trimethylchlorosilane (TMSCl) promoted multicomponent reaction (MCR) of ethylenediamine(s), diverse carbonyl compounds, and isocyanides is proposed for the synthesis of a variety of highly substituted 3,4,5,6-tetrahydropyrazin-2-amines including corresponding spirocyclic compounds.     

Thermal expansion of thin C60 films

The thermal expansion coefficient a and structure of C₆₀ films with thickness t∼3–10 nm were investigated in the temperature interval from room to liquid-nitrogen temperature by electron-optical methods. The thermal expansion coefficient was determined from the temperature shift of the diffraction maxima in the electron diffraction patterns. The objects of investigation were epitaxial C₆₀ films condensed in vacuum on a (100) NaCl cleavage surface and oriented in the (111) plane. A surface-induced size effect in the thermal expansion coefficient was observed. It was established that as t decreases α _f increases and is described well by the relation α _f=17·10⁻⁶ K⁻¹+8.3·10⁻⁵ nm K⁻¹ t ⁻¹. This relation was used to estimate the linear expansion coefficient α _s of the C₆₀ surface in the (111) plane as α _s=60·10⁻⁶K⁻¹, which is several times larger than the bulk value. The experimental results agree satisfactorily with the theoretical calculations of the mean-square displacements of molecules located in a region near the surface. Zh. éksp. Teor. Fiz. 114, 1868–1875 (November 1998)     

Bimetallic Rh-Co/ZrO<Subscript>2</Subscript> catalysts for ethanol steam reforming into hydrogen-containing gas

The properties of supported bimetallic Rh-Co/ZrO₂ catalysts in ethanol steam reforming into hydrogen-containing gas were studied. The particles of Rh-Co solid solutions on the catalyst surface were prepared by the thermal decomposition of the double complex salt [Co(NH₃)₆][Rh(NO₂)₆] and the solid solution Na₃[RhCo(NO₂)₆]. It was found that the bimetallic Rh-Co/ZrO₂ catalysts exhibited high activity in the reaction of ethanol steam reforming. The equilibrium composition of reaction products was attained at 500–700°C and a reaction mixture space velocity of 10000 h⁻¹.     

Deexcitation of plasma by relativistic electrons

The characteristics of the electromagnetic radiation generated as a result of the interaction of relativistic electrons with a plasma are investigated. The main attention is paid to the analysis of the effect of broadening mechanisms on the bremsstrahlung energy spectrum of the relativistic electrons propagating in a carbon plasma upon deexcitation of its components.     

Building up of Macroring in the New Synthesis of Azacrown Ethers. Structure and Complex Formation of Nitrobenzoazacrown Ethers

A cyclization of azapodand haloderivatives into nitrobenzoazacrown ethers under treatment with various bases and in their absence was investigated. The nitrobenzoazacrown ethers obtained and their complexes with metal cations were studied by X-ray diffraction method and by ¹H NMR titration. In nitrobenzoaza-15-crown-5 a capability to complex Ca²⁺ cation was found that significantly exceeded similar ability of nitrobenzocrown ether with the same size of the macroring.     

Macroring Opening in Crown Ethers. Transformation of (4′-Formylbenzo)thiacrown Ethers into Podands by the Action of Methylamine

A procedure has been developed for the synthesis of thiaaza podands from (4′-formylbenzo)thiacrown ethers via nucleophilic regioselective opening of the macroring by the action of methylamine and methylamine hydrochloride on heating.__________Translated from Zhurnal Organicheskoi Khimii, Vol. 41, No. 3, 2005, pp. 468–471.Original Russian Text Copyright © 2005 by Dmitrieva, Churakova, Gromov.     

Host-guest complexes of nitro-substituted N-alkylbenzoaza-18-crowns-6

Russian Journal of Organic Chemistry - A number of N-alkyl(nitrobenzo)aza-18-crowns-6 in which the nitrogen atom in the macroring is conjugated with the benzene ring were synthesized, and their...     

New methodology for the synthesis of benzoazacrown ethers by transformation of the macrocycle of benzocrown ethers

The review summarizes the results of studies aimed at constructing new promising macrocyclic ligands that bind metal and ammonium ions. A new approach to the synthesis of formyl and nitro derivatives of 1-aza-2,3-benzocrown ethers possessing considerable synthetic potential is described. The review presents a radically new methodology for the synthesis of such benzoazacrown ethers based on stepwise transformations of the macrocycle of readily accessible benzocrown ethers. The main structural factors and necessary conditions enabling stepwise transformations of the macrocycle of crown ethers into azacrown ethers were revealed. For the first time, the ability of N-methylbenzoazacrown ethers to form complexes was found, which is much superior to that of widely used N-phenylazacrown ethers and benzocrown ethers with the same size of the macrocycle.