Materials Literature
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Enge Bandlücken und hohe Elektronenaffinitäten zeichnen konjugierte Oligomere aus, die Thiophen-1-oxid- und Thiophen-1,1-dioxid-Einheiten enthalten und durch Zirconocen-vermittelte Kupplungsreaktionen synthetisiert wurden. Eine Reihe von Oligomeren mit drei bis elf Ringen (X=2 H, S=O, S(=O)2; siehe Bild) ermöglichte e…
N,N'-Bis(2-propenyl)-2,7-diazapyrenium salts are synthesized in good yield from the reaction of 1,4,5,8-naphthalenetetracarboxylic dianhydride with allylamine, followed by LiAlH(4) reduction and subsequent oxidation with 2,3-dichloro-5,6-dicyano-1,4-benzoquinone (DDQ). The nature of the counteranion depends on the sol…
The stretching-induced alpha−beta polymorphic transition in the crystalline regions of poly(butylene terephthalate) (PBT) is studied by small-angle X-ray scattering (SAXS), instead of by the wide-angle X-ray scattering (WAXS) usually used for this purpose. An expression for the increase of the long spacing upon the tr…
A Cayley tree is the structural motif of the dendrimerlike supramolecular structure that is formed by self-assembly of the bile salt sodium deoxycholate (NaDC) with the β-cyclodextrin trimer T (see schematic picture). This is the first example of dendritic growth by a cyclodextrin complex.
Optical components, such as miniature spectrometer gratings working in the infrared range for environmental monitoring or physical analytics, contribute appeciably to the price of Micro Electro Opto Mechanical Systems (MOEMS). These optical components could be a part of a miniature functional package produced with an…
Pig heart CoA transferase (EC 2.8.3.5) has been shown previously to adopt a homodimeric structure, in which each subunit has a molecular weight of 52 197 and consists of N- and C-domains linked by a hydrophilic linker or "hinge". Here we identify and characterize a second oligomeric form constituent in purified enzyme…
NO and NO2 associated as the asymmetric N2O3 conformer compete with water molecules for coordination with sodium cations of the sodium–water clusters in supercages of the Na-Y zeolite. This reactive NOx adsorption is reversible (see picture), not sensitive to SO2, and presents an alternative method for the removal of…
Crystalline stereocomplex formation of isotactic poly(methyl methacrylate) ( it -PMMA) and syndiotactic poly(methyl methacrylate) ( st -PMMA) induced by high-pressure CO 2 at pressures in the 5−35 MPa range and at temperatures in the 30−110 °C range was demonstrated by means of differential scanning calorimetry (DSC)…
A high-spin ground state S>8 is obtained through ferromagnetic coupling in a FeIIFe complex that models the electronic properties of Prussian blue. The picture shows the postulated core structure for this heptanuclear complex.
Clusters of lithium atoms ranging in size from Li4 to Li40 and bulk metallic solids, including surfaces, are investigated through first principles electronic structure calculations, which are based upon density functional theory and the electron localization function (ELF). It is found that large lithium ppi-type cont…
Chromium acetyl acetonate [Cr(acac)3] complexes have been grafted onto the surface of two mesoporous crystalline materials; pure silica MCM-41 (SiMCM-41) and Al-containing silica MCM-41 with an Si:Al ratio of 27 (AlMCM-41). The materials were characterized with X-ray diffraction, N2 adsorption, thermogravimetrical ana…
ADVERTISEMENT RETURN TO ISSUEPREVCommunicationNEXTUmpolung of a Metal−Carbon Bond: A Potential Route to Porphyrin-Based Methane Functionalization CatalystsAndrew P. Nelson and Stephen G. DiMagnoView Author Information Department of Chemistry, University of Nebraska-Lincoln Lincoln, Nebraska 68588-0304 Cite this: J. Am…
Note : No abstract
Transmission electron micrographs (TEM) of UO 2 2+ -negatively stained starburst dendrimers (SBDs), members of the family of dendritic macromolecules, have been analyzed in the absence and in the presence of dimyristoyl-phosphatidylcoline (DMPC) liposomes and mixed DMPC/DMPA-Na (the sodium salt of DMP-colate) liposome…
Enzymatic ring-opening copolymerization of 5-methyl-5-benzyloxycarbonyl-1,3-dioxan-2-one (MBC) with trimethylene carbonate (TMC) was investigated. A route to aliphatic polycarbonates decorated with pendent carboxylic acid groups is demonstrated. Lipase from Pseudomonas fluorescens (AK) was selected to perform the copo…
Lineare, polymere Polyanionen entstehen aus lakunären Polyoxowolframat-Einheiten und Lanthanoid-Ionen (siehe Bild). Angesichts der vielen Lanthanoide und lakunären Polyoxoanionen ist damit eine beträchtliche Zahl an neuen Materialien zugänglich.
Adjusting the pore size and volume of molecular sieve MCM-41 over a very wide range is possible through simple hydrothermal treatment of “off the shelf”, as-synthesized materials in a decyldimethylamine (DMDA)–water emulsion (see schematic representation). The amine/silica ratio as well as the time and temperature of…
ADVERTISEMENT RETURN TO ISSUEPREVCommunicationNEXTHigh Efficiency Near-IR Emission of Nd(III) Based on Low-Vibrational Environment in Cages of Nanosized ZeolitesYuji Wada, Tatsuya Okubo, Munenori Ryo, Toru Nakazawa, Yasuchika Hasegawa, and Shozo YanagidaView Author Information Material and Life Science, Graduate Schoo…
The square hole for the round peg: The first two members of a new family of tetrametallic cyclophanes (1; M=MnI, ReI), which feature rectangular cavities, have been synthesized and characterized. Both of the luminescent compounds behave as mesoporous materials in a thin film and display high capacities and substantial…
The first purely organic BEDT-TTF spin-Peierls system, b'-(ET)2SF5CF2SO3, has been confirmed using a high-frequency electron spin resonance (EPR) cavity perturbation technique. The material exhibits the characteristics of a quasi-one-dimensional (1D) Heisenberg antiferromagnetic spin system above 30 K, but undergoes a…