ABSTRACT
The Zn(II) ion in the title compound, [Zn(C(24)H(28)N(2)O(6))](n), is located on a twofold rotation axis and is at the midpoint of a crown-4 moiety of 3,3'-[(1,7-dioxa-4,10-diaza-cyclo-dodecane-4,10-di-yl)bis-(methyl-ene)]dibenzoate anion. It is octahedrally coordinated by two N atoms and two O atoms of the crown moiety from one ligand and two carboxyl-ate O atoms from two bridging intra-chain ligands. Metallomacrocyclic rings are identified in the structure. The metallomacrocycle contains two Zn(II) ions and 14 atoms from the bridging ligands. Repetition of these units gives rise to an infinite zigzag chain along [101]. C-Hâ¯O hydrogen bonds occur.
ABSTRACT
Vertically aligned zinc oxide (ZnO) nanowires (NWs) have been grown by liquid injection Metal Organic Chemical Vapour Deposition, using oxygen donor adducts of Me2Zn. The growth and characterisation of the nanowires grown using [Me2Zn(L)] where L = monodentate ethers, tetrahydrofuran (C4H8O) (1), tetrahydropyran (C5H10O) (2), furan (C4H4O) (3) and the bidentate ethers, 1,2-dimethoxyethane (C4H12O2,) (4) 1,4-dioxane (C4H8O2) (5) and 1,4-thioxane (C4H8SO) (6) is discussed. Single crystal X-ray structures of (4), (5), (6) have been established and are included here. The ZnO NWs were deposited in the absence of a seed catalyst on Si(111) and F-doped SnO2/glass substrates over the temperature range 350-600 degrees C. X-ray diffraction (XRD) data shows that the nanowires grown from all adduct precursors were deposited in the wurtzitic phase.
ABSTRACT
Porous materials find widespread application in storage, separation, and catalytic technologies. We report a crystalline porous solid with adaptable porosity, in which a simple dipeptide linker is arranged in a regular array by coordination to metal centers. Experiments reinforced by molecular dynamics simulations showed that low-energy torsions and displacements of the peptides enabled the available pore volume to evolve smoothly from zero as the guest loading increased. The observed cooperative feedback in sorption isotherms resembled the response of proteins undergoing conformational selection, suggesting an energy landscape similar to that required for protein folding. The flexible peptide linker was shown to play the pivotal role in changing the pore conformation.
Subject(s)
Carbon Dioxide/chemistry , Dipeptides/chemistry , Zinc/chemistry , Adsorption , Chemical Phenomena , Crystallization , Diffusion , Hydrogen Bonding , Ligands , Magnetic Resonance Spectroscopy , Models, Molecular , Molecular Dynamics Simulation , Molecular Structure , Porosity , Pressure , Protein Conformation , Protein Folding , Solvents , Thermodynamics , X-Ray DiffractionABSTRACT
We investigate the normal state of the "11" iron-based superconductor FeSe0.42Te0.58 by angle-resolved photoemission. Our data reveal a highly renormalized quasiparticle dispersion characteristic of a strongly correlated metal. We find sheet dependent effective carrier masses between approximately 3 and 16m{e} corresponding to a mass enhancement over band structure values of m{*}/m{band} approximately 6-20. This is nearly an order of magnitude higher than the renormalization reported previously for iron-arsenide superconductors of the "1111" and "122" families but fully consistent with the bulk specific heat.
