Materials Literature
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A new class of saturated hydrocarbons, in which a spiropentane-type unit is bound by a cyclic hydrocarbon, has been investigated by using ab initio molecular orbital calculations at the B3-LYP and MP2 levels. These molecules have been given the trivial name hemispiroalkaplanes. Hemialkaplanes, which are analogous mole…
Polyglutamic dendritic porphyrins of the general formula H2PophGlu(N)OR (H2Porph = free-base meso-tetra-4-carboxyphenylporphyrin (H2TCPP), Glu=dendrimer layer composed of L-glutamates, N= 1-3: dendrimer generation number, R = terminal group (All, H)) were synthesized and characterized with NMR and MALDI-TOF mass spect…
The synthesis of the shape-persistent macrocycles 10a and 10b with two bipyridine units in opposing sides by Hagihara/Sonogashira cross-coupling chemistry of suitably functionalized building blocks is reported. X-ray analysis of single crystals of 10b shows a layered structure with channels filled with solvent molecul…
It is found that an icosahedral quasicrystalline phase is directly formed in a Zr80Pt20 binary alloy during rapid solidification from the melt. The size of the icosahedral particles lies in the diameter range below 10 nm, and the particles are distributed homogeneously. The formation of the nanoscale icosahedral phase…
Zweizähnig verbrückendes molekulares Diiod wurde erstmals in [Rh2(O2CCF3)4I2]⋅I2 nachgewiesen, das durch Abscheidung aus der Gasphase erhalten wurde. Einer Kristallsturktuanalyse zufolge liegt eine Zickzack-Polymerkette aus alternierenden [Rh2(O2CCF3)4]- und I2-Molekülen vor (siehe Bild); ein weiteres Diiod-Molekül is…
The degradation behavior of integrated Pt/SrBi2Ta2O9/Pt capacitors by hydrogen impregnation during the intermetal dielectric deposition and passivation is investigated. The hydrogen ions generated as a reaction byproduct from the SiH4-based deposition processes of the dielectric films induce reduction in the remanent…
Investigations of the frequency dependence of the P–E (polarization versus field) and ε–E (strain versus field) behavior have been performed on soft 0.7Pb(Mg1/3Nb2/3)O3–0.3PbTiO3 polycrystalline ferroelectrics at various maximum field strengths below and above that of the coercive field (Ec). For E<Ec, a strong…
A precious metal cartwheel is one way to describe the novel heteronuclear compound [Au6Ag(μ-C6H2iPr3)6]CF3SO3 (see picture, isopropyl groups are omitted) which displays an unusual planar hexacoordination for the silver(I) center. A convenient and simple synthesis of new gold heterometallic clusters is presented.
The surface Debye temperature of the NiMnSb (100) epitaxial films has been obtained using low energy electron diffraction, inverse photoemission, and core-level photoemission. The normal dynamic motion of the (100) surface results in a value for the effective surface Debye temperature of 145±13 K. This is far smaller…
CdSe quantum dots, in the form of colloidal nanocrystals, are bound to the surface of a gold electrode by bisulfide spacer molecules. The distance dependance of the electron transfer rate between the CdSe and the electrode was investigated by a time-resolved optoelectronic method and related to the length r of the spa…
An experimental method based on the 3ω technique has been developed to measure thermal conductivity of porous Xerogel films as a function of porosity. The results show that the thermal conductivity of these porous dielectric films can be an order of magnitude smaller than that of SiO2. To account for the porosity depe…
The postulated low thermal conductivity and the possibility of altering the electronic conductivity of metal-doped clathrates with semiconducting host elements have stimulated great interest in exploring these compounds as promising thermoelectric materials. The electronic and thermal properties of the prototypical Na…
The first five generations of the stilbenoid dendrimers 1(n) (n = 1-5) have been prepared by a combined coupled synthesis (between the generations of the dendrons 8-12) and convergent synthesis. Wittig-Horner reactions together with a protecting group technique yield monodisperse compounds of high constitutional and c…
We report that Co metal nanoparticles (an average diameter of 4 nm) chemically synthesized by a reverse micelle method catalyzes the growth of multiwall carbon nanotubes (MWNTs) aligned perpendicular to a substrate. The surface of the nanoparticles is covered with surfactants so that the nanoparticles can be dispersed…
Electronic properties of heterojunctions between metallic and semiconducting single-wall carbon nanotubes are investigated. Ineffective screening of the long-range Coulomb interaction in one-dimensional nanotube systems drastically modifies the charge transfer phenomena compared to conventional semiconductor heterostr…
The thinnest possible boron polymer strand is found in LiBx (0.82<x<1.0, see picture) and can be described by the two mesomeric forms =[B−=]nB−= or −[B−. The compound LiBx consists of an aligned array of such boron wires embedded in a lithium matrix. Furthermore, each boron atom yields one negative charge and, thus, b…
For a solid in which the interactions have a hard core plus a simple soft repulsive tail we show, using a perturbation theory, that the possible stable crystalline structures give rise to a rich phase behavior. We find two concomitant critical points each corresponding to phase transitions separating bcc and fcc struc…
A bidentate bridging coordination of molecular diiodine has been found for the first time in [Rh2(O2CCF3)4I2]⋅I2, which was obtained by deposition from the vapor phase. An X-ray structure reveals a zigzag chain polymer (shown in the picture) formed by alternating [Rh2(O2CCF3)4] and I2 molecules; another diiodine molec…
Small organic gelling agents very efficiently self-assemble into an entangled network in a wide variety of organic solvents, thereby turning the liquid into a gel. Recent progress in the design of organogelators led to tailor-made gelling agents for supercritical CO2. Furthermore, such agents can be used as templates…
That flexible side groups pointing to the outside are not essential for the formation of discotic liquid crystals is displayed by the structure of 1, in which the rigid core functions as the periphery and the alkyl chains point toward the inside.