Materials Literature
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A new interpretation of the optical and energy-loss spectra of hexagonal boron nitride is provided based on first-principle calculations. We show that both spectra cannot be explained by independent-particle transitions but are strongly dominated by excitonic effects. The lowest direct and indirect gaps are much large…
Thermophilic organisms flourish in varied high-temperature environmental niches that are deadly to other organisms. Recently, genomic evidence has implicated a critical role for disulfide bonds in the structural stabilization of intracellular proteins from certain of these organisms, contrary to the conventional view…
The $\ensuremath{\pi}$-stacking interaction between various planar organic molecules is investigated within the framework of ab initio calculations. The adsorption of these molecules on the sidewall of the cylindrical carbon structure induces a small binding energy compared to conventional covalent functionalization.…
A convenient process for generating large-scale, horizontally aligned arrays of pristine, single-walled carbon nanotubes (SWNTs) is described. The approach uses guided growth, by chemical vapor deposition (CVD), of SWNTs on miscut single-crystal quartz substrates. Studies of the growth reveal important relationships b…
White light was generated from a single silica thin film made with Yb0.75La0.2Eu0.05F3, La0.45Yb0.5Er0.05F3, and La0.75Yb0.2Tm0.05F3 nanoparticles by exciting with a single source near-infrared light (980 nm CW diode laser). Eu3+ and Tm3+ ions are responsible for red and blue emission, respectively. Er3+ ion is respon…
Individual carbon nanotubes are like minute bits of string, and many trillions of these invisible strings must be assembled to make useful macroscopic articles. We demonstrated such assembly at rates above 7 meters per minute by cooperatively rotating carbon nanotubes in vertically oriented nanotube arrays (forests) a…
Rb2[AuII2][AuIIII4], dirubidium diiodoaurate(I) tetraiodoaurate(III), has a tilted and distorted perovskite-type structure which is isotypic with its bromide analogue Rb2[AuIBr2][AuIIIBr4]. The structure contains compressed and elongated [AuI6] octahedra tilted away from each other and stacked alternately along th…
Abstract For the first time we studied Raman, exciton and EPR spectra of PbI 2 layered crystals of 2H polytype doped with high concentration of Mn impurity. A novel type of Fermi resonance was found. The anomalous temperature shift of the exciton band n = 1 was registered. It was shown that this shift can be explained…
Abstract Near‐spherical dendrimers can be used as templates for bottom‐up syntheses of semiconductor clusters. Starting from methanolic solutions of Cd 2+ , sulfide, and poly(amidoamine) dendrimers, CdS clusters precipitate at the dendrimers. A preparation inside the dendrimers is only possible when the protonation of…
Crystals of CsGd(PO3)4 have been grown by the flux technique from a mixture of CsH2PO4, Gd2O3 and H3PO4. CsGd(PO3)4 crystallizes in structure type IV of the MIMIII(PO3)4 (MI = alkali metal, MIII = rare earth or Bi) family of compounds. The structure consists of a three-dimensional framework made up of spiral (PO3)n ch…
Direct 1N-amination of the triazole-fused zinc phthalocyanine 2 and oxidation of the formed amino derivative 3 resulted in the generation of the very reactive intermediate, the dehydrometallophthalocyanine 4, which was not known previously. The latter was trapped in situ with different dienes, for example, furan, tetr…
The Sparkle/AM1 model is extended to ytterbium (III) complexes. Thus, a set of 15 complexes, with various representative ligands, chosen to be representative of all complexes of high crystallographic quality (R-factor <0.05 A) in the Cambridge Crystallographic Database, and which possess oxygen and/or nitrogen as coor…
Die selektive Keimbildung von Aragonit lässt sich mit Blockcopolymer-Mikrogelen sehr niedriger Konzentration (0.1 ppm) bei Umgebungsbedingungen in Wasser erreichen. Ein Polymertemplatpartikel genügt, um die Bildung eines Rings aus Aragonit-Einkristallen zu steuern, die sich zu einer Garbenstruktur weiterentwickeln (si…
Von linear zu dendritisch: Glycin ist Teil der in Kollagenproteinen vorherrschenden Sequenz, und Aspartat ähnelt der Wiederholungseinheit von Poly(benzylglutamaten) (PBGs). Kollagen und PBGs sind lineare Peptide, die sich zu Fasern selbst organisieren, flüssigkristalline Phasen bilden und Lösungsmittel gelieren können…
The phase behavior of a two-dimensional colloidal system subject to a commensurate triangular potential is investigated. We consider the integer number of colloids in each potential minimum as rigid composite objects with effective discrete degrees of freedom. It is shown that there is a rich variety of phases includi…
A porphyrin molecule containing four meso-appended 2,2'-bipyridyl ligands has been prepared. Each bipyridine is attached to the porphyrin core at the 4-position (pseudo-para to one of the pyridine nitrogens). Subsequently, each of the four bipyridines was complexed with a RuL2(2+) moiety and iron coordinated in the po…
Recently synthesized zinc helicenocyanine (ZnHc), where four helicene groups are fused with a phthalocyanine (Pc) core through all-carbon linkages, exhibits an unusually strong tendency of forming soluble molecular aggregates in organic solvents. The aggregation results in a strong optical absorption across most of th…
The cobalt(II) and iron(II) siloxane compounds were prepared by the reaction of lipophilic N-bonded silanetriol 1 with metal silylamides M[N(SiMe3)2]2 (M = Co (2), Fe (3)) in a 1:1 and 3:4 molar ratio, respectively. A plot of 1/chi versus temperature in the range of 2-300 K indicates the paramagnetic behavior of 2 and…
Both the intermolecular interaction energies and the geometries for $M\ensuremath{\cdots}$ thiophene, $M\ensuremath{\cdots}$ pyrrole, ${M}^{n+}\ensuremath{\cdots}$ thiophene, and ${M}^{n+}\ensuremath{\cdots}$ pyrrole (with $M=\mathrm{Li}$, Na, K, Ca, and Mg; and ${M}^{n+}={\mathrm{Li}}^{+},\phantom{\rule{0.3em}{0ex}}{…
Wankelmütig: In einem einfachen elektrochemischen Prozess werden superhydrophobe leitende Polypyrrol(PPy)-Filme hergestellt. Diese Filme sind durch eine ausgedehnte poröse Struktur mit Rauigkeit auf der Grob- wie der Feinskala gekennzeichnet (siehe Bild). Über die Wahl des elektrischen Potentials können die PPy-Filme…