Materials Literature
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A series of phthalocyanines containing four dendritic substituents with terminal ester or carboxylate functionalities have been synthesized. These compounds having bulky substituents are essentially nonaggregated in organic solvents (for the ester series) or water (for the [G 1 ] and [G 2 ] carboxylate series) as demo…
The sorption of Zn vapor at 480 °C onto fully dehydrated fully Cd 2+ -exchanged zeolite X (Cd 46 Si 100 Al 92 O 384 per unit cell) has been studied at 23 °C by single-crystal X-ray diffraction in the cubic space group Fd 3̄ ( a 0 = 24.895(3) Å). In this structure, Cd 46 Si 100 Al 92 O 384 ·20Zn, Cd 2+ ions are found a…
Recent photoabsorption measurements have revealed a rich fine structure in the collective charge-density excitation spectrum of few-electron quantum dots in the presence of magnetic fields. We have performed systematic computational studies of the far-infrared density response of quantum dots, using time-dependent den…
The effect of annealing polycarbonate at 125 °C (≈ T g − 20 K) for aging times up to almost 2000 h has been investigated by differential scanning calorimetry, and the kinetics of the enthalpy relaxation process are compared with the effects of aging at the same temperature on the creep response and on the yield behavi…
The resistivity and thermopower of Na$_{1+x}$Co$_2$O$_4$ and Na$_{1.1-x}$Ca$_x$Co$_2$O$_4$ are measured and analyzed. In Na$_{1+x}$Co$_2$O$_4$, whereas the resistivity increases with $x$, the thermopower is nearly independent of $x$. This suggests that the excess Na is unlikely to supply carriers, and decreases effect…
Die Umlagerung der Ag4-Clusterkerne der lumineszierenden Silber(I)-Komplexe mit Bis(diphenylphosphanyl)bipyridin (P2-bpy), die bei der Bindung von zusätzlichen Liganden an die Ag-Zentren erfolgt (siehe Bild), führt zur Löschung der Emission. Die Löschung tritt mit O2, CO, NO und mit koordinierenden Lösungsmitteln wie…
Materials that develop large shape changes in the magnetic field at a short response time provide a new method of producing motion and force in electromechanical devices. The strains are based on the magnetic-field-induced reorientation of the twin variants of the material. This effect is called magnetic shape memory…
Die stufenweise Desalkylierung von meso-Octaethylporphyrinogen 1 liefert Porphomethen 2 und Porphodimethen 3, wodurch große Mengen dieser wertvollen Zwischenprodukte zugänglich werden. Die Synthesesequenz beruht auf der Reaktion mit SnCl4⋅2 THF, Li und H2O; das Ausmaß der Desalkylierung hängt von der eingesetzten Meng…
Despite the high neutron absorption of natural europium, the crystal structures of two Eu hydrides could be solved from powder diffraction data. EuMg2D6 crystallizes in a novel AB2X6 structure type (see picture), EuMgD4 is isotypic to BaZnF4. The mean Eu−D distances are 258 and 253 pm, respectively.
... This paper describes a practical engineering approach and compares predictions with the results from several experimental studies.
Large magnetic field induced strain shave been reported in ferromagnetic shape memory alloys. two such alloys, Ni-Mn-Ga and Fe-Ni-Co-Ti are explored. A single crystal of Ni-Mn-Ga is shown to deformed by bending approximately six degrees under the influence of an applied field. This deformation is caused by the motion…
Lanthanide, main group, and transition metal ion templates provide different polynuclear cages from [M(L)] (M=Ni, Mn; (L)2−=CH2[CH2N=C(CH3)COO−]2). Templating with lanthanum results in a 12-coordinate LaIII ion encapsulated by six [Ni(L)] units, whereas with sodium four Na+ ions are trapped inside a tricapped trigonal…
A new type of heterogeneous, polystyrene-bound catalyst is introduced: A cross-linking, dendritic ligand, the TADDOL 1, is copolymerized with styrene, loaded with titanate, and used for the enantioselective catalysis of the addition of Et2Zn to PhCHO. The polymer-bound catalyst has an unprecedented efficiency and stab…
We have observed the electronic states at conducting polymer/conducting oxide interfaces using a low-energy photoelectron spectroscopic method. The electronic states of conducting polymer/indium tin oxide (ITO) interfaces were different from those of conducting polymer/metal interfaces. The electron transfer from a co…
The acid-catalyzed ammonolysis of the hitherto unknown compound tris(dimethylamino)silylamine (1), which is prepared from SiCl4 in high yield and purity, results in the preparation of a silicon diimide gel. The probable first step in this process is the acid-catalyzed self-condensation of 1 to the cyclic trimer [{(CH3…
⋅2 THF employed.
Hydrothermal synthesis provides new vanadium borophosphates. BP2O10 trimers and V2O8 dimers are connected by common oxygen atoms to give a building unit of composition (VO)2BP2O10. Four-, five-, and six-rings are formed by further connection of these units; the first case is shown schematically. The ring size of the a…
Based on density functional theory the influence of curvature on the depletion potential of a single big hard sphere immersed in a fluid of small hard spheres with packing fraction ${\ensuremath{\eta}}_{s}$ either inside or outside of a hard spherical cavity of radius ${R}_{c}$ is calculated. The relevant features of…
First model-independent measurements of the hydrogen diffusivity $D$ in lanthanum trihydrides ${\mathrm{LaH}}_{x}$ $(2.00\ensuremath{\le}x\ensuremath{\le}3.0)$ have been performed by PFG-NMR. At a fixed concentration $x\ensuremath{\le}2.92$, $D(T)$ shows single Arrhenius behavior over wide temperature ranges. The acti…
The popular “high-electric-field” technique to determine the polar anchoring coefficient W of a nematic–substrate interface requires the simultaneous measurement of the capacitance and optical phase retardation of a liquid crystal cell as a function of applied voltage. We develop a generalized model that makes it poss…