Morphological transformation of Co(OH)2 microspheres from solid to flowerlike hollow core-shell structures.

We report, for the first time, a detailed investigation into the formation of highly uniform, 3D, flowerlike, hollow, spherical architectures of cobalt hydroxide through a facile solvothermal process. Various controlling parameters were examined, such as water content in starting materials, reaction time, cobalt(II) precursor concentration, and reaction temperature. On the basis of the experimental results, the formation mechanism of these flowerlike cobalt hydroxide hollow spheres involves aggregation of cobalt hydroxide building clusters into solid spheres and hollowing effect through subsequent dissolution, diffusion, and re-deposition of the smaller crystallites under the surface layer driven by an Ostwald ripening process. Metallic cobalt hollow spheres have also been obtained by thermal decomposition of cobalt hydroxide flowers in a mixed gas of Ar+4 % H(2) at 400 degrees C. The morphology and composition of the products were characterized by X-ray diffraction, field-emission scanning electron microscopy, energy-dispersive X-ray spectroscopy, and (high resolution) transmission electron microscopy.

Characterization of Ag nanoparticle superlattice structure prepared using two carboxylic acids.

One-step hydrothermal process is introduced for the synthesis of highly ordered self-assembled Ag nanoparticles. Ag nanoparticles with same diameter and narrow size distribution are synthesized in the presence of the mixture of two capping molecules, the combination of sodium oleate and aromatic carboxylic acid. Self-assembled 3D superlattice structures of Ag nanoparticles are synthesized in aqueous system without any post-procedure. Effects of aromatic carboxylic acid to sodium oleate and the nature of interaction between nanoparticles in superlattices are characterized with TEM examinations and FT-IR spectra.

Isolation and characterization of the first stable bicarbonato complex in a nickel(II) system: identification of unusual monodentate coordination.

The stable monodentate Lindskog type bicarbonate nickel(ii) complex and its isomer have been prepared and fully characterized.

Ketene-forming eliminations from aryl bis(4'-chlorophenyl)acetates promoted by R2NH-R2NH2+ in aqueous MeCN. Change of mechanism.

Elimination reactions of (4'-ClC6H4)2CHCO2C6H3-2-X-4-NO2 promoted by R2NH-R2NH2+ in 70 mol% MeCN (aq.) have been studied kinetically. The reactions are second-order and exhibit Brönsted beta = 0.44-0.86 and /beta(lg)/ = 0.41-0.71. The Brönsted beta decreased with a poorer leaving group and /beta(lg)/ increased with a weaker base. The results are consistent with an E2 mechanism. When X=H, the reaction proceeded by the concurrent E2 and Elcb mechanism.