Materials Literature
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An immensely broad scope of structural motifs is covered by the intriguing chemistry of boron–sulfur and boron–selenium compounds. Characteristic structural features of the binary boron sulfides can be applied to understand and rationalize the three-dimensional atomic arrangement in macromolecular anionic frameworks s…
Self-organization is the key. A series of dendritic pseudorotaxanes were efficiently constructed from complementary building blocks-namely, a three-armed, triply charged ammonium salt and the first, second, and third generations of benzyl ether dendrons bearing the dibenzo[24]crown-8 moiety. The pseudorotaxane arising…
ADVERTISEMENT RETURN TO ISSUEPREVCommunication to the...Communication to the EditorNEXTNovel Starlike Poly(methyl methacrylate)s by Controlled Dendritic Free Radical InitiationAndreas Heise, James L. Hedrick, Mikael Trollsås, Robert D. Miller, and Curtis W. FrankView Author Information IBM Research Center, 650 Harry R…
The direct benzene hydroxylation by an iron−oxo species is discussed from density-functional-theory (DFT) calculations. The proposed reaction pathway is FeO + + C 6 H 6 → OFe + (C 6 H 6 ) → [TS1] → HO−Fe + −C 6 H 5 → [TS2] → Fe + (C 6 H 5 OH) → Fe + + C 6 H 5 OH, in which TS means transition state. This reaction is in…
Da hätten wohl auch Platon und Kepler ihre Freude gehabt! Trotz der großen Zahl an Atomen weist das Cluster-Anion 1 eine ikosaedrische Struktur auf – sicherlich ein Novum in der Geschichte der Chemie! Es setzt sich derart aus 12 {Mo11}-Fragmenten zusammen, daß im resultierenden kugelförmigen Gebilde die fünfzähligen D…
By illumination with white light porous silicon surfaces can be functionalized with alkynes and alkenes (see scheme). The hydrosilylation reactions are very simple to perform and lead to stable, patterned surfaces. This methodology opens new opportunities in the technological applications of porous silicon in both int…
The rational synthesis and the structural and magnetic characterization of three different nickel clusters encapsulated in Keggin trivacant fragments are presented. The three complexes show how it is possible to increase the nuclearity of the clusters (from 3 and 4 to 9) by slightly changing the synthetic conditions.…
Incarcerated in a helical prison: The encapsulation of a PF6− ion within a quadruply stranded helicate (shown schematically) results from the self-assembly of four molecules of 1,4-bis(3-pyridyloxy)benzene and two PdII ions. This represents not only the first example of a coordinatively saturated quadruple helicate, b…
We performed coarse-grained simulations of thin polyethylene films of different thicknesses at 509 K. The films, which present two surfaces to vacuum, are formed from monodisperse melts of C 100 H 202 . The mobility increases toward the free surfaces at the scale of individual beads and chains due to the decrease in d…
The preparation and characterization of several (nitro)(nitrosyl)iron(III) complexes, [Fe(Porph)(NO 2 )(NO)], where Porph = tetraphenylporphyrin, octaethylporphyrin, tetra- p -methoxyphenylporphyrin, or picket fence porphyrin, are described. Crystal data: [Fe(T p -OCH 3 PP)(NO 2 )(NO)]·CH 2 Cl 2, tetragonal, space gro…
A new procedure is described for the formation of a hyperbranched poly(ether ketone) with carboxylic acid terminal groups. This preparation was based on the one-step synthesis of an AB 2 -type monomer 5-phenoxyisophthalic acid using phosphorus pentoxide/methanesulfonic acid as the condensing agent and solvent. The ele…
Surface modifications of Ar plasma-pretreated poly(tetrafluoroethylene) (PTFE) film via UV light-induced graft copolymerization with 1-vinylimidazole (VIDz) and glycidyl methacrylate (GMA) were carried out to improve the adhesion with evaporated copper. The surface compositions of the graft-copolymerized PTFE films we…
Enhanced luminescence resulting from energy transfer (EnT) from nucleic acids to Tb 3+ has been utilized to investigate the binding of the ions to the bases and nucleotides, as well as in the detection of single mismatches in duplexes. Cytosine enhances the Tb 3+ emission, but dCMP does not, indicating that the lantha…
Syntheses and characterization of two polymorphs of Cu(TCNQ) have been carried out and the results correlated to films of the materials. Reactions of CuI with TCNQ or [Cu(CH 3 CN) 4 ][BF 4 ] with TCNQ - lead to blue-purple needles of Cu(TCNQ) phase I ( 1 ). A slurry of this kinetic product in CH 3 CN yields a second c…
The reduction-diffusion process was developed for the production of rare earth - transition metal intermetallics for magnetic purposes. The process consists in the formation of the intermetallic through the diffusion of the rare earth formed by the reduction of its oxide with metallic calcium and the transition metal.…
The reaction of K2S3, Ta and S yields single crystals of tripotassium tetrathiotantalate, K3TaS4. The compound crystallizes with the K3VS4-type structure [van den Berg & de Vries (1964). Proc. K. Ned. Akad. Wet. Ser. B, 67, 178–180]. The structure is based on discrete tetrahedral TaS43− anions, which are connected via…
In the title compound, C3H8NO2+.C2HO4.H2O, the amino acid molecule exists with a protonated amino group and an uncharged carboxylic acid group. The oxalic acid molecule is found to exist in the monoionized state. The structure is stabilized by an extensive network of hydrogen bonds.
A new vanadium phthalocyanine complex with the formula [VI(C32H16N8)], or PcVI (Pc=C32H16N8), has been obtained by the reaction of pure V powder with 1,2-dicyanobenzene under iodine vapour. The V atom is bonded to one apical iodide ligand and four Nisoindole atoms, and has a square pyramidal coordination geometry. The…
The phytoplankton of lake Zempoala was studied from April 1996 to July 1997. The taxonomy, ecology and geographical distribution of species show that their presence is more common in temperate than tropical areas. Seasonal variations in patching, density and dominant species of the phytoplankton are corresponding with…
The crystal structure of α-Sr2P2O7, distrontium diphosphate, has been refined by X-ray diffraction using single crystals grown from a SrLiPO4-P2O5 melt cooled between 1323 and 1073 K. The fully anisotropic refinement confirms the centrosymmetric Pnma space group, but also reveals a strong anisotropy along the b direct…