Materials Literature
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Licht steuert das Resultat einer stereoselektiven Reaktion. Nur in seiner offenen Form kann der gezeigte Chelat-Kupfer(I)-Komplex seine Chiralität auf die Cyclopropanierung von Styrol mit Ethyldiazoacetat übertragen. Einstrahlung von UV-Licht löst die Ringschlussreaktion des Liganden aus, die ihn wirkungslos macht.
We present a novel method for the preparation of ultrasmall Au/CdSe core/shell particles. Au-Cd bialloy particles of 4.7 nm diameter were prepared as the precursor. The Cd component in the precursor reacted with the Se source at a temperature of 205 degrees C and was heated to 250 degrees C, leading to formation of a…
Films of poly(L-lactide) [i.e., poly(L-lactic acid) (PLLA)] and L-lactide copolymers with glycolide [P(LLA-GA)(81/19)], epsilon-caprolactone [P(LLA-CL)(82/18)], D-lactide [P(LLA-DLA)(95/5), (77/23), and (50/50)] were prepared and a comparative study on the effects of comonomer type and content on alkaline and proteina…
The broad-band visible emission of codoped ZnO was studied. The codoped ZnO specimens were intentionally and simultaneously doped with IIIa elements (donors) and Li (acceptor). Broad-band emission covering nearly the whole visible range was achieved. The emission was found to be yellowish white to the naked eye. The v…
Abstract Summary: Eleven laboratory‐evolved polyhydroxyalkanoate (PHA) synthases which originated from Pseudomonas sp. 61‐3 enzyme (PhaC1 Ps ), together with the wild‐type enzyme, were applied for PHA synthesis from fructose using Ralstonia eutropha PHB ‐ 4 as a host strain. The evolved PhaC1 Ps mutants had amino acid…
The ferromagnetic interstitial iron compound Fe(3)C (cementite) is expected to have Invar properties, whereby a high-moment to low-moment transition should occur when the atomic volume is reduced below a critical value. We, therefore, examine the pressure dependence of the Fe K-edge x-ray magnetic circular dichroism i…
Abstract Polyaniline (PANI) in three ground states—emeraldine base (EB), leucoemeraldine base (LEB), and pernigraniline base (PNB)—were studied by Raman spectroscopy in the temperature scale of −195 to about 375°C. The Raman spectral results demonstrated that a crosslinking reaction occurred on EB chains at high tempe…
Two kinds of triphenylamine-containing AB 2 monomers carrying or not carrying flexible alkyl chains were synthesized and fully characterized. One-pot Suzuki polycondensation (SPC) was applied to polymerize these monomers to prepare hyperbranched polymers. Hyperbranched polymers from AB 2 monomer not carrying alkyl cha…
The mechanism responsible for liquid crystal (LC) alignment on mechanically buffed or UV exposed polymer films is poorly understood. A comprehensive study of LC alignment on variously prepared substrates unequivocally shows that the anisotropy in the surface roughness of the substrate completely determines the directi…
Abstract Summary: Three‐dimensional polyaniline (PANI) nanowire networks were synthesized in high yield using a “soft template” self‐assembled with hexadecyltrimethylammonium bromide and oxalic acid. The PANI nanowire networks had diameters from 35–100 nm depending on synthesis conditions and/or procedures. The networ…
Abstract Summary: The glass transition temperatures of conducting composites, obtained by blending carbon nanotubes (CNTs) or polypyrrole (PPy) particles with epoxy resin, were investigated by using both differential scanning calorimetry (DSC) and dynamical mechanical thermal analysis (DMTA). For both composites, dc a…
The new ligands Na[(p-IC6H4)B(3-Rpz)3] (R = H, Me) have been prepared by converting I2C6H4 to IC6H4SiMe3 with Li(t)Bu and SiMe3Cl, and then to IC6H4BBr2 with BBr3 and subsequent reaction with 3 equiv of (un)substituted pyrazole and 1 equiv of NaO(t)Bu. These new ligands react with FeBr2 to give either purple, low-spin…
[structure: see text] A urea-containing tetraphenoxy-substituted perylene bisimide has been synthesized, and its gelation ability has been studied. This functional dye forms fluorescent organogels in toluene and tetrachloromethane through self-assembly by hydrogen-bonding and pi-pi-stacking interactions. AFM and confo…
We report the structural and magnetic properties of polycrystalline ferriferricyanide, $\mathrm{Fe}[\mathrm{Fe}{(\mathrm{C}\mathrm{N})}_{6}]∙4{\mathrm{H}}_{2}\mathrm{O}$. The room temperature neutron diffraction pattern of the sample was refined with space group $Fm3m$ by the Rietveld refinement technique. The M\"ossb…
Self-assembled tapes: Adsorption and self-assembly of peptides on mica substrates produces tapes, a single molecule in thickness, with a cross-β-sheet structure (see picture). A variety of surface morphologies may be produced depending on the preparation procedure. One of these, a close-packed monolayer of parallel-al…
Tungsten oxide-organic layered hybrid materials have been studied by infrared and Raman spectroscopy and demonstrate a difference in bonding nature as the length of the interlayer organic "spacer" molecule is increased. Ethylenediamine-tungsten oxide clearly displays a lack of terminal -NH3(+) ammonium groups which ap…
We construct shells with tunable morphology and mechanical response with colloidal particles that self-assemble at the interface of emulsion droplets. Particles self-assemble to minimize the total interfacial energy, spontaneously forming a particle layer that encapsulates the droplets. We stabilize these layers to fo…
Light controls the outcome of a stereoselective reaction. Only in the ring-open form can the shown chelate copper(I) complex transfer its chirality to the cyclopropanation of styrene with ethyl diazoacetate. Irradiation with UV light triggers the ring-closing reaction of the ligand rendering it ineffective (see scheme…
Charge ordering in the low-temperature monoclinic structure of iron oxoborate (Fe2OBO3) is investigated using the local spin density approximation (LSDA)+U method. While the difference between t_{2g} minority occupancies of Fe^{2+} and Fe^{3+} cations is large and gives direct evidence for charge ordering, the static…
In this paper we give a brief review of the relation between microscopic dynamical properties and the Fourier law of heat conduction as well as the connection between anomalous conduction and anomalous diffusion. We then discuss the possibility to control the heat flow.