Nature of hydrogen atom trapped inside palladium lattice

Colloid of palladium nanoparticles has been prepared by the Solvated Metal Atom Dispersion (SMAD) method. Reaction of Pd(0) nanopowder obtained upon precipitation from the colloid, with ammonia borane (H3N center dot BH3, AB) in aqueous solutions at room temperature results in the generation of active hydrogen atoms. The active hydrogen atoms either combine with one another resulting in H-2 evolution or diffuse into the Pd lattice to afford PdHx. Diffusion of hydrogen atoms leads to an expansion of the Pd lattice. The diffused hydrogen atoms are distributed uniformly over the entire particle. These features were established using powder XRD and electron microscopy studies. The H-1 NMR spectral studies of PdHx before and after desorption of H-2 revealed that the hydrogen atoms trapped inside Pd lattice are hydridic in nature. Desorption of hydrogen from PdHx did not result in complete reversibility suggesting that some hydrogen atoms are strongly trapped inside the Pd lattice. (C) 2010 Professor T. Nejat Veziroglu. Published by Elsevier Ltd. All rights reserved.

Oxide-based bifunctional oxygen electrode for rechargeable metal/air batteries

Statistical methods for optimizing the morphology of oxide-based, bifunctional oxygen electrodes for use in rechargeable metal/air batteries are examined with regard to binder composition, compaction time, and compaction load. Results show that LaNiO3 with PTFE binder in a nickel mesh envelope provides a satisfactory electrode.

Attaching chelating ligands to polybenzimidazole via epoxidation to obtain metal selective sorbents

Microporous polybenzimidazole of 250–500 μm spherical bead size from Celanese has been reacted with epichlorohydrin and sodium hydroxide and the resulting product with pendant epoxy groups has been reacted with various chelating ligands in order to augment the metal sorption capacity and selectivity of the resin. The chelating ligands used include ethylenediamine, diethylenetriamine, diethanolamine, dimethylglyoxime, L-cysteine, thiourea, dithiooxamide, glyoxal-bis-2-hydroxyanil, salicylaldehyde-ethylenediimine, and glyoxal-bis-2-mercaptoanil. The aminolysis of the pendant epoxy groups with the oligoamines has been performed in pyridine under reflux conditions, while the addition reactions with the other ligands which are alkali soluble have been carried out at room temperature in a mixture of dioxane and aqueous KOH using tetra-n-butylammonium iodide as the phase transfer catalyst. The products are found to possess high capacity and selectivity in metal sorption depending on the ligand attached.

Crystal structure of 2-thiophene-2-yl-3(thiophene-2-carboxylideneamino)-1,2-dihydroquinazolin-4(3H)-one and the synthesis, spectral and thermal studies of its transition metal(II) complexes

The synthesis of manganese(II), cobalt(II), nickel(II), copper(II), zinc(II) and cadmium(II) complexes of a new ligand 2-thiophene-2-yl-3(thiophene-2-carboxylidene-amino)-1,2-dihydroquinazolin-4(3H)-one (TTCADQ) is described. The ligand and metal complexes were characterized by elemental analysis, conductivity measurements, spectral (u.v.-vis., i.r., 1D n.m.r., 2D hetcor and e.p.r.) and thermal studies. The formation of 1,2-dihydroquinazolin-4(3H)-one rather than hydrazone, in the reaction of aromatic aldehyde and o-aminobenzoylhydrazide is proved by single crystal X-ray diffraction and 2D hetcor n.m.r. studies. On the basis of elemental analysis, u.v.-vis.spectroscopy and magnetic moment studies, six coordinate geometry for all the complexes was proposed. The i.r. spectral studies reveal the bidentate behaviour of the ligand.