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Co-doped ZnO films were synthesized by ion beam sputtering using multilayer (ZnO/Co) growth. Both the distribution and the chemical states of Co in ZnO can be well controlled by varying the ratio of the nominal layer thickness of ZnO to Co. Transmission electron microscopy indicated that all of the as-deposited Zn1-x(Co)xO films were polycrystalline with a (0002) preferred orientation. The local microstructures and chemical states were identified by Z-contrast imaging and electron energy loss spectroscopy. In ZnO (1.5 nm)/Co (0.1 nm), homogeneous Co-doped ZnO was observed to have been formed through interdiffusion. However, decreasing or increasing the thickness of ZnO leads to the formation of Co clusters in the ZnO matrix or Zn1-x(Co)xO multilayers, respectively. For ZnO thickness≧1.5 nm, Co is substituted for Zn, and its valence state is 2+. All Co-doped ZnO films show room-temperature ferromagnetic behavior, which appears to depend strongly on the Co distribution. [ABSTRACT FROM AUTHOR]

A cobalt-catalyzed dual annulation reaction for the synthesis of variously substituted indenoisoquinolinones from 2-bromobenzaldehydes, amines, and methyl 2-(ethynyl)benzoates has been developed. This method could also be applied to the synthesis of an array of highly functionalized bioactive indenoisoquinolinones and their derivatives. A possible mechanism of the cobalt catalysis is proposed, involving imine formation from bromobenzaldehyde and the amine, followed by a series of oxidative addition, alkyne insertion, cyclization reactions, and carbon-carbon double-bond migration. The regioselective alkyne insertion plays an important role for the success of the second annulation. [ABSTRACT FROM AUTHOR]

Abstract: The role of cobalt in oxide-mediated silicidation is studied in terms of diffusion and nucleation by varying annealing conditions, oxide thickness and implantation in Si substrate. Electroscopic imaging in transmission electron microscopy shows that SiO x act as a one-way diffusion barrier reducing the Co effective concentration at the cobalt silicide growth interface leading to CoSi2 as the first formation phase during silicidation. X-ray photoelectron spectroscopy analysis shows that unreacted Co coexists with CoSi2 at the interface between the SiO x layer and Si substrate, implying that Co diffusion rate is faster than CoSi2 nucleation rate. An Si-implanted substrate can increase the CoSi2 nucleation rate and reduce the Co accumulation. [Copyright &y& Elsevier]

A novel metal-organic framework Co(bnbc)(C5H5N)3(complex1) (H2bnbc = 2,2′-dibenzyl-1,1′-binaphthyl- 3,3′-dicarboxylic acid) has been synthesized under mild conditions and structurally characterized. IR spectra indicates that the coordination mode of carboxyl group of complex1is chelating bidentate with the Co2+ion. Crystal structural analysis reveals that complex1adopts a one-dimensional (1D) infinite line structure, and the distance between two carbon atoms of the pair carboxyl groups is 8.226 Å which is longer than other analogs. The complex1is further assembled into a 2D supramolecular network through the hydrogen bonds. Thermogravimetric analysis (TGA) shows that complex1is highly thermally stable up to 150°C. X-ray powder diffraction (PXRD) of complex1shows that single crystalline structure is as the same as the huge mass small crystalline structure confirming its purity of phase. Meanwhile, the photoluminescent property of the complex1is investigated. [ABSTRACT FROM AUTHOR]

A novel metal-organic framework Co(bnbc)(C5H5N)3(complex1) (H2bnbc = 2,2′-dibenzyl-1,1′-binaphthyl- 3,3′-dicarboxylic acid) has been synthesized under mild conditions and structurally characterized. IR spectra indicates that the coordination mode of carboxyl group of complex1is chelating bidentate with the Co2+ion. Crystal structural analysis reveals that complex1adopts a one-dimensional (1D) infinite line structure, and the distance between two carbon atoms of the pair carboxyl groups is 8.226 Å which is longer than other analogs. The complex1is further assembled into a 2D supramolecular network through the hydrogen bonds. Thermogravimetric analysis (TGA) shows that complex1is highly thermally stable up to 150°C. X-ray powder diffraction (PXRD) of complex1shows that single crystalline structure is as the same as the huge mass small crystalline structure confirming its purity of phase. Meanwhile, the photoluminescent property of the complex1is investigated. [ABSTRACT FROM PUBLISHER]