A. N. Zakharov

Zeolite included Fe(II)Phthalocyanine

The title compound was prepared by treating iron(0) or pentacarbonyl-iron(0) containing Y zeolite with the appropriate complexant. Because of steric hindrance, the phthalocyanine guest molecule, turns out to be encapsulated within the zeolite cavity.

Surface state of sacrificial copper electrode by electropolishing in hydrophobic ionic liquid 1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide.

Anodic dissolution of natural surface-oxidized, air-annealed, cathodically reduced, and cathodically deposited copper in hydrophobic ionic liquid 1-buthyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide under galvanostatic conditions by means of gravimetric measurements was studied. The resulting samples were mirror-like oxide-free copper pattern. The mechanism of the electropolishing of oxidized copper surface was considered. The consequent anodic reactions Cu2O - 1e = Cu(+) + CuO, CuO - 2e = Cu(2+) + O, and Cu - 1e = Cu(+) take place. The electropolishing itself occurs over oxygen-free copper surface due to competitive residual water discharge in the pits and copper dissolution on the roughness.

Catalytic behavior of copper(II) chelate complexes sterically held in zeolite large cavities and fixed on its outer surface by a topological anchor

Catalytic properties of copper(II) tricyclic chelate compounds based on enamino ketone of 3-acetyl-2,4-pentanedione and 1,6-hexametylenediamine fixed on NaY and CaA zeolites by the methods of topological and topologically-anchor retention, respectively, were compared. The mode of fixation of chelates on a support affects the character of the liquid-phase catalytic oxidation of cyclohexene by molecular oxygen. At the topological fixation by a steric retention of a chelate compound in a large cavity of NaY zeolite, the reaction rate related to one reaction center of a metal complex is not proportional to the filling degree that points to inaccessibility for a substrate of catalyst molecules localized in inner cavities of crystallites. In an alternative mode of the catalyst topologically-anchor fixation, when only a ligand fragment is held in CaA zeolite, and catalytically active metal center is turned to the side of the reaction medium, the linear dependence of the cyclohexene oxidation rate on the amount of the chelate on the support is retained within the whole studied range of the surface catalyst concentrations. The catalytic activity of the topologically-anchor fixed Cu(II) chelate compound coincides with its activity in the zeolite absence, which points to a pseudo-homogeneous mode of cyclohexene oxidation. At topologically-anchor fixation of a Cu(II) chelate compound on CaA zeolite diffusion limitations characteristic for the fixation by steric retention are completely eliminated.

Chemical model for dioxin destruction in aqueous medium: Electrocatalytic oxidation of dioxin-like substance simulating natural pollutant

Chemical model for destruction of dioxin in aqueous phase was suggested. Eosin being similar to dioxins in structure was chosen as a model substance. Eosin seemed to undergo destruction in electrocatalytic systems. For the first time, the adsorption of dioxin-like pollutant, eosin, was detected on platinum electrode at higher potentials than those of oxygen evolution. The kinetics of electrocatalytic oxidation was studied. A total oxidation of substrate to mineral products (carbonates, bromates) occurred over platinized-platinum catalyst. The scheme for electrocatalytic destruction of eosin was discussed. The similar behavior of dioxin in electrocatalytic systems was considered on the basis of the structural similarity and kinetic relationship in eosin and dioxin oxidation.

Iron-containing nanoparticles based on the 2-hydroxypropyl-β-cyclodextrin in aqueous solutions

The water-soluble hybrid nanoparticles based on high-substituted 2-hydroxypropyl-β-cyclodextrin were formed in situ during the reduction of iron(+2) salts by hypophosphite ion in alkaline medium. These nanoparticles are high sensitive to temperature and ultrasonication. It was established that the temperature and ultrasonication time of exposure increase leads to the successive dissociation of the nanoparticles.

Metal-free thermally-responsive pseudohybrid nanoparticles based on 2-hydroxypropyl-β-cyclodextrin

Pseudohybrid nanoparticles of 800 nm in diameter based on self-assembled high-substituted 2-hydroxypropyl-β-cyclodextrin fabricated in the presence of iron(II) salts were found to be thermally responsive within narrow range of temperature. As-prepared metal-free nanoparticles are stable in aqueous solution at room temperature. However, the increase in temperature results in break-like collapse of nanoparticles to yield species of 400 nm in diameter. On the example of phenolphthalein, it was shown that nanoparticles loaded with model drug decompose to release superficial guest-host inclusion complexes. Local hyperthermia provokes nanoparticles decomposing and drug releasing that allows recognizing focuses of pathology in human body. It might be used for diagnostic medicinal aims and be also considered as basis for the construction of intravascular drug delivery/release systems.

Thermal and spectral features of nickel compounds synthesized within the pores of photonic crystals based on SiO 2

Nanoparticles of NiC2O4 · 2H2O were obtained within the interspheric voids of synthetic opal polycrystalline samples based on SiO2. The thermal decomposition of NiC2O4 · 2H2O inclusions within the pores of crystallites was studied by means of thermal gravimetry and differential scanning calorimetry under static conditions in atmospheres of He and air. The efficient activation energy of dehydration (180 ± 10 kJ mol−1) and dehydration enthalpy of nickel oxalate crystalline hydrate (69.9 kJ mol−1) within the pores of photonic crystals based on SiO2 were calculated. Pyrolysis of the nickel oxalate led to the formation of NiO nanoparticles within the voids and on the external surface of the photonic crystallites. The behavior of polycrystalline samples of the photonic crystals in a medium of immersion liquids was studied. It was shown that the partial population of the interspheric pores of photonic crystals with NiC2O4 · 2H2O, NiO, and Ni that diffuse visible light do not lead to a total loss of light conductivity in the immersion medium. The diffuse reflection spectra of a sample of photonic crystals populated with NiC2O4 · 2H2O and NiO phases were recorded. A sample of photonic crystals with inclusions of metallic nickel particles exhibiting magnetic properties was obtained by treating nickel oxide-containing synthetic opal based on SiO2 with molecular hydrogen.

Polythermic decomposition of Co(COO)2 · 2H2O compound synthesized within pores of photonic crystals based on SiO2

Polythermic decomposition of Co(COO)2 · 2H2O synthesized within pores of photonic crystals based on SiO2 was studied by thermogravimetry and differential scanning calorimetry techniques in helium and air in flow and under static conditions. Efficient activation energies and dehydratation enthalpies of the photonic crystals based on SiO2 both in the absence and in the presence of Co(COO)2 · 2H2O phase (23.6, 41.5 and 77.6, 49.8 kJ mol-1, respectively) were calculated. Polythermic Co(COO)2 · 2H2O decomposition within pores of the photonic crystallites was found to yield CoO and Co3O4 nanoparticles in helium and air, respectively, exhibiting higher catalytic activity in CO oxidation by molecular oxygen. A conclusion was drawn that exothermic effect in the temperature range covering dehydrated oxalate decomposition is due to heterogeneously catalytic CO oxidation on the CoO and Co3O4 phases.

Catalytic properties of monomeric and oligomeric Cu(II) phenylhydrazono imine chelates immobilized on zeolite with a topological anchor

Heterogeneous catalysts for liquid-phase oxidation of cyclohexene with molecular oxygen were prepared by topological-anchor immobilization on CaA zeolite of a monomeric Cu(II) chelate with N,N′-trimethylenebis(2-methyl-1-benzoylglyoxal 1-phenylhydrazone 2-imine) and of an oligomeric product of its condensation with ethylenediamine. The samples prepared contain surface monomeric and oligomeric Cu(II) chelates oriented toward the reaction medium, which makes them accessible to reactant molecules. The catalytic properties of the above monomeric chelate are preserved in going to the oligomers. The apparent rate constants per metal center for both homogeneous (soluble monomeric chelate) and heterogeneous modes coincide, suggesting the pseudohomogeneous behavior of the supported samples. The topological-anchor immobilization of insoluble oligomeric Cu(II) polychelates on zeolite leads to their more efficient utilization as heterogeneous catalysts and can be considered as one of examples of combining advantages of homogeneous and heterogeneous catalysis.