Materials Literature
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Der Hydroxysubstituent machts möglich! Im Gegensatz zum nichtaromatischen Benziporphyrin 1a (X H) ist beim Hydroxyderivat 1b (X OH) das durchkonjugierte, vollständig aromatische Semichinon‐Tautomer 2 begünstigt. magnified image
Formaler Austausch der Pyrrolkerne in Porphyrin durch Bipyrrol‐Einheiten führt zu der Titelverbindung 1 . Das Hexadecaethyl‐Derivat von 1 ist einziges isolierbares Produkt der MacDonald‐Kondensation sowohl geeigneter tetrapyrrolischer als auch dipyrrolischer Komponenten. Das neue Cyclooctapyrrol liegt im Kristall und…
Die Cyclooctapyrrole 1‐3 sind eindrucksvolle Beispiele dafür , daß bei der Kondensation von dipyrrolischen Bausteinen die Bildung von Cyclooctapyrrolen gegenüber der entsprechender Cyclotetrapyrrole bevorzugt sein kann, wenn die Cyclisierung zu letzteren konformativ behindert ist. Die Makrocyclen sind chiral und könnt…
The real-space structure of hard-sphere glasses quenched from colloidal liquids in thermodynamic equilibrium has been determined. Particle coordinates were obtained by combining the optical sectioning capability of confocal fluorescence microscopy with the structure of specially prepared fluorescent silica colloids. B…
Abstract A key reaction in the biological and material world is the controlled linking of simple (molecular) building blocks, a reaction with which one can create mesoscopic structures, which, for example, contain cavities and display specifically desired properties, but also compounds that exhibit typical solid‐state…
A high-intensity electron gun based on field emission from a film of aligned carbon nanotubes has been made. The gun consists of a nanotube film with a 1-millimeter-diameter grid about 20 micrometers above it. Field-emission current densities of about 0.1 milliampere per square centimeter were observed for applied vol…
X-ray diffraction (XRD) has been used for the study of bi-intercalation of ICl into the stage-5 ${\mathrm{FeCl}}_{3}$ graphite intercalation compound (GIC). The stage-5 ${\mathrm{FeCl}}_{3}$ GIC is obtained when the temperature of graphite is set at 788 K, and the temperature of ${\mathrm{FeCl}}_{3}$ at 573 K in the t…
Recent investigations of the compound NaSn (1:1) have indicated that both fast conduction of ${\mathrm{Na}}^{+}$ cations and rapid reorientations of (${\mathrm{Sn}}_{4}$${)}^{4\mathrm{\ensuremath{-}}}$ anions are present in the high-temperature solid phase, \ensuremath{\alpha}-NaSn. We have used $^{23}\mathrm{Na}$ and…
Plasmids containing the ebgAo and ebgAa genes of Escherichia coli under the control of the lac repressor and promoter have been constructed and inserted into Salmonella typhimurium CH3. This system expresses the large subunit of the ebgo and ebga beta-galactosidase in high yield (20-60% of total protein). The large su…
Luminescence associated with small PbI 2 clusters formed in Pb 1- x Cd x I 2 solid solutions has been investigated in the range of x between 0.4 and 0.9. Time-resolved measurements reveal that the luminescence at the absorption edge of crystals consists of the bands with short (sub-ns) and long (µ s ) decay times. The…
The ${\mathrm{Si}}_{28}$ and M@${\mathrm{Si}}_{28}$ (M=tetravalent atoms) clusters have been studied by the density-functional theory. We find that both ${\mathrm{Si}}_{28}$ and ${\mathrm{C}}_{28}$ clusters have similar electronic structures and the dangling bonds of the ${\mathrm{Si}}_{28}$ cluster can be stabilized…
InGaMgO4 and InGaZnO4 crystals with the YbFe2O4 layered structure have been found to be transparent conductive oxides. The band gaps of these crystals were wider than that of In2O3. Conductivity was induced by doping with electrons through introduction of oxygen vacancies. Mobility, carrier density and conductivity of…
We report on the proton spin–lattice relaxation measurements in the isotropic and nematic phases of the liquid crystal 4′-pentyl-4-cyanobiphenyl (5CB), constrained by a low-concentration polymer network. Above the nematic–isotropic transition, a relatively small impact of the network in the MHz regime and a huge incre…
Optical study of trivalent 3 d transition metal oxide compounds LaSr M O 4 ( M =Cr, Mn, Fe and Co) with layered perovskite structure has revealed fundamental features of their electronic structures. Systematic change of the charge-transfer gap ( E gap ) with the 3 d element ( M ) can be explained by a simple ionic mod…
Spectra of optical absorption (3 eV ∼ 6 eV) and emission (2.9 eV ∼ 4.1 eV) have been investigated on Ce 3+ centres in YAlO 3 :Ce 3+ single crystals at 297 K; excitation spectrum for 360 nm light in the Ce 3+ emission band region has also been measured in the region of 3.5 eV ∼ 6.2 eV. Measurement of excitation spectru…
Abstract Synthesis of 1,5‐bis(4‐fluorobenzoyl)‐2,6‐dimethylnaphthalene ( 1 ), polycondensation of 1 with Bisphenol A, and properties of the obtained polymer were studied. Friedel–Crafts acylation of 2,6‐dimethylnaphthalene with 4‐fluorobenzoyl chloride in nitrobenzene selectivity afforded 1 in 82% yield. X‐ray single…
An 18-site, three-ring model has been developed for the van der Waals system ortho-terphenyl (OTP) which has been studied extensively experimentally because of its glass forming ability. The method of constraints has been used to freeze out the fast internal modes of the molecule, but the model retains some internal m…
Atomic-scale images of the (001) surface of monoclinic ${\mathrm{WO}}_{3}$ have been obtained by scanning tunneling microscopy. Termination of the surface ${\mathrm{WO}}_{2}$ plane with half a monolayer of oxygen ions gives a surface periodicity \ensuremath{\surd}2 times that of the underlying ${\mathrm{ReO}}_{3}$-lik…
Abstract Surface graft polymerization of glycidyl methacrylate (GMA) was carried out onto a high‐ density polyethylene (PE) sheet pretreated with corona to introduce peroxides onto the PE surface. Graft polymerization of GMA was effected by UV irradiation of the coronatreated PE in the presence of monomer solution wit…
The structure of the title compound, CsLiB 6 O 10 , comprises eight-coordinate Cs atoms and four-coordinate Li atoms, and an anion network of chains formed from B 3 O 7 groups. The Cs and Li atoms occupy alternate sites in the channel along the c axis.