Meltable, Glass-Forming, Iron Zeolitic Imidazolate Frameworks

We describe the first meltable iron-based zeolitic imidazolate framework (ZIF), denoted MUV-24. This material, elusive from direct synthesis, is obtained from the thermal treatment of [Fe3(im)6(Him)2], which yields Fe(im)2 upon loss of the neutral imidazole molecules. Different crystalline phase transformations are observed upon further heating, until the material melts at 482 °C. Vitrification upon cooling of the liquid phase gives rise to the first Fe-metal-organic framework glass. X-ray total scattering experiments show that the tetrahedral environment of the crystalline solids is maintained in the glass, whereas nanoindentation measurements reveal an increase in Young's modulus, in agreement with stiffening upon vitrification

Growth mechanism of solution-deposited layers of the charge-transfer salt CuDDQ

Charge-transfer (CT) salts such as copper-2,3-dichloro-5,6-dicyano-p-benzoquinone (CuDDQ) are promising components of reversible resistive memory switching devices. In the study presented here, we report on the composition of CuDDQ layers grown from acetonitrile containing solution onto copper-coated silicon substrates. According to Rutherford Backscattering Spectrometry (RBS) experiments, the CuDDQ film is homogeneously composed of copper and DDQ across its whole thickness, and the ratio between copper and DDQ is 1:1. A complex between copper and acetonitrile has been identified by Electro Spray Ionization (ESI) time-of-flight mass spectrometry as the main source of copper ions for the CuDDQ layer formation. In contrast, if ethanol is used as solvent, no copper-ethanol complex can be discerned from the ESI mass spectrum. This finding underlines the vital role of acetonitrile as the main copper source for the complexation reaction with DDQ. The continuous availability of the copper-acetonitrile complex in solution during the growth of the CuDDQ layers explains their homogeneity as determined by RBS. (c) 2007 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim

White light-emitting electrochemical cells based on the langmuir-blodgett technique

Light-emitting electrochemical cells (LECs) showing a white emission have been prepared with Langmuir-Blodgett (LB) films of the metallosurfactant bis[2-(2,4-difluorophenyl)pyridine][2-(1-hexadecyl-1H-1,2,3-triazol-4-yl)pyridine]iridium(III) chloride (1), which work with an air-stable Al electrode. They were prepared by depositing a LB film of 1 on top of a layer of poly(N,N\u2032-diphenyl-N,N\u2032-bis(4-hexylphenyl)-[1,1\u2032-biphenyl]-4,4\u2032-diamine (pTPD) spin-coated on indium tin oxide (ITO). The white color of the electroluminescence of the device contrasts with the blue color of the photoluminescence of 1 in solution and within the LB films. Furthermore, the crystal structure of 1 is reported together with the preparation and characterization of the Langmuir monolayers (\u3c0-A compression isotherms and Brewster angle microscopy (BAM)) and LB films of 1 (IR, UV-vis and emission spectroscopy, X-ray photoelectron spectroscopy (XPS), specular X-ray reflectivity (SXR), and atomic force microscopy (AFM))

Electrochemically modified single-walled carbon nanotubes

p s s basic solid state physics b s

Isolated Mn-12 single-molecule magnets grafted on gold surfaces via electrostatic interactions

Electrostatic interactions drive the adsorption of polycationic single-molecule magnets onto anionic monolayers self-assembled on gold surfaces. Well-isolated magnetic clusters have been deposited and characterized using scanning tunneling microscopy and X-ray photoemission spectroscopy