New palladium nanoclusters. Synthesis,structure, and catalytic properties

The reduction of palladium(ii) carboxylates Pd₃(OCOR)₆ (R = Me, Et, CHMe₂, CMe₃) with hydrogen in alcohol solutions containing 1,10-phenanthroline (phen) and subsequent oxidation with oxygen gave new palladium nanoclusters, mainly particles with a nearly spherical metal core and an average size of 18 . Based on elemental analysis, NMR, X-ray photoelectron spectroscopy, and EXAFS, nanoclusters were described by the idealized formula Pd₁₄₇phen₃₂O₆₀(OCOR)₃₀. The specimens contained up to 25% smaller 55-atomic Pd clusters with a 10 metal core. New nanoclusters catalyze hydrogenation of alkynes and alkenes, reduction of nitriles with formic acid, oxidation of aliphatic and benzylic alcohols, oxidative esterification of ethylene and propylene, and disproportionation of benzyl alcohol into toluene and benzaldehyde.     

Effect of mechanical activation on the catalytic, physical and chemical properties of copper oxide

Mechano-chemical activation of copper oxide powders leads to structural disordering of the near-surface layers of particles and, thus, to considerable variations in the catalytic properties of copper oxide.

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Synthetic Cu0.507(5)Pb8.73(9)Sb8.15(8)I1.6S20.0(2) nanowires

Nanowires of an iodine containing Pb-Sb-sulfosalt have been synthesized by chemical vapor transport. Their structure was studied using high-resolution transmission electron microscopy and X-ray powder diffraction. The lattice parameters show values equal to a=4.9801(4) nm, b=0.41132(8) nm (with two-fold superstructure), c=2.1989(1) nm and β=99.918(6)°. These parameters and the results of a multislice simulation are in good agreement with the mineral pillaite, Cu_0.10Pb_9.16Sb_9.84S_22.94Cl_1.06O_0.5 (space group C2/m, a=4.949(1) nm, b=0.41259(8) nm, c=2.1828(4) nm, and β=99.62(3)°). Microprobe and EDX analyses yielded a chemical composition of Cu_0.507(5)Pb_8.73(9)Sb_8.15(8)I_1.6S_20.0(2) which is close to natural pillaite but contains no oxygen and iodine instead of chlorine. The structure of the investigated material is based on chains of M-S polyhedra (M=Pb or Sb) typical for the architecture of sulfosalts implying iodine atoms in trigonal prismatic coordination with Pb atoms from the M-S polyhedra of neighboring chains. The [010] superstructure of the specimen was found to be unstable under electron beam irradiation with a rapid decrease of the b lattice parameter from 0.8 to 0.4 nm within 5 min.     

Formation of supported size-controlled nanoparticles of sulfated zirconia

Methods of the preparation of catalysts for alkane skeletal isomerization based on uniform nanoparticles of sulfated zirconia anchored to different supports were investigated. These catalysts were characterized by using the ICP, HRTEM and BET techniques. The activities of the catalysts in the reaction of n-butane isomerization were measured and compared with those of bulk catalysts.     

Intergrowth between V2O5 and TiO2 (anatase): High resolution electron microscopy evidence

V₂O₅/TiO₂ (anatase) with 5 and 20 wt.% loadings of V₂O₅ have been studied using high resolution electron microscopy. This has provided the first direct evidence for the formation of a coherent interfacial boundary between two crystalline TiO₂ and V₂O₅ phases. The type of the interfacial stacking was found to be similar for all the samples, whereas the length of the boundary formed depended on the V₂O₅ loading. A model for the atomic arrangement of this boundary based on a comparison of structural positions of oxygen and metal atoms in the crystal lattices of both phases is proposed.     

Nature of extended defects of CuO

For the first time, using high-resolution electron microscopy, extended defects (twins, screw dislocations and microdistortions) of disperse CuO have been found. Their structure is described.

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A study of the effect of kaolin fibers on properties of elastomeric heat-protection materials

Russian Journal of Applied Chemistry - The effect of kaolin fibers on the physicomechanical, thermal, and fire-and-heat-protective characteristics of elastomeric composites based on...     

Synthesis,X-ray and DFT Studies of 6-halo-3-(hydroxymethyl)cinnolin-4(1H)-ones

Chemistry of Heterocyclic Compounds - The Richter cyclization was used for the synthesis of 6-halo-3-(hydroxymethyl)cinnolin-4(1H)-ones. X-ray analysis revealed that these compounds exist as dimers...     

Small-angle X-ray scattering study of the influence of solvent replacement (from H<Subscript>2</Subscript>O to D<Subscript>2</Subscript>O) on the initial crystallization stage of tetragonal lysozyme

The composition of lysozyme solutions in D₂O under conditions favorable for the formation of tetragonal crystals has been investigated at different protein concentrations by small-angle X-ray scattering using the synchrotron radiation. In addition to lysozyme monomers, dimeric and octameric species are found in the crystallization solutions; the octamer content increases with an increase in the protein concentration. A comparison of the data with those obtained under similar conditions but with H₂O used as a solvent has shown that the replacement of light water with heavy one leads to increase of octamer volume fraction in solution.