Materials Literature
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BIOMATERIALSNo one knows how the glasslike silica laceworks within the cell walls of diatoms are formed, but on page [1129][1], biochemists report new clues--silica-forming proteins dubbed silaffins that, when added to solutions of silicic acid, a silicon-containing organic compound, precipitate to form networks of mi…
Two oxothiophosphato anions are obtained from solutions containing the [Mo2S2O2]2+ precursor and phosphate ions. The monophosphato anion reveals a Mo10 decameric structure and the diphosphato anion, a Mo12 dodecameric one. Both compounds exhibit an open cavity containing the phosphate ions. A 31P NMR study in solution…
The hydrothermal reactions of V 2 O 5, H 2 C 2 O 4, Ni(NO 3 ) 2, ethylenediamine(en) or 1,2-diaminopropane(enMe) and water yield layered vanadium oxides with interlayer metal coordination complexes [Ni(en) 2 ] 0.5 [V 3 O 7 ] ( 1 ) and [Ni(enMe) 2 ] 0.5 [H 2 enMe] 0.5 [V 6 O 14 ] ( 2 ). 1 crystallizes in an orthorhombi…
Long alkyl-chain quaternary ammonium salts bearing two hydroxyethyl groups at the polar head group form smectic A mesophases at high temperatures and ordered smectic T mesophases of tetragonal symmetry at lower temperatures. The latter phase resembles a supermolecular grid (figure); it is formed by a hydrogen-bonding…
Lewis and Brønsted acidic aluminosilsesquioxanes have been synthesized and utilized as homogeneous models for the corresponding acidic aluminum sites found in aluminosilicates and zeolites.
A reversible reaction with dioxygen is observed for the copper(I) complex [Cu(Me6tren)]+ (Me6tren=tris(2-dimethylaminoethyl)amine) at low temperatures. This complex displays an interesting crystal structure (depicted) and the interaction with dioxygen in solution was investigated by low-temperature UV/Vis spectroscopi…
Traditionally, magnetic materials have been metals or, if inorganic compounds such as oxides, of continuous lattice type. However, in recent years chemists have synthesized increasing numbers of crystalline solids based on molecular building blocks in the form of coordination and organometallic complexes or purely org…
Many ceramics are resistant to heat, corrosion, and wear, and they are used in applications ranging from coffee mugs to dental implants to protective tiles on the space shuttle. But they also break easily, and the maximum stress they can withstand varies unpredictably from component to component. Promising new approac…
Simple peroxomolybdenum Mimoun complexes become catalytically active in phase-transfer epoxidations with hydrogen peroxide, if the active oxenoid is extracted from the water into the organic phase by surfactant-type ligands OER3 (E = N, P, As; R = long-chain alkyl; see scheme). Mechanistic studies, Raman spectroscopy,…
A novel and efficient method for the production of enantiomerically pure (R)-(-)-hydroxycarboxylic acids by in vivo depolymerization of microbial polyester polyhydroxyalkanoates (PHAs) was developed. Using this method, several model compounds, (R)-(-)-3-hydroxyalkanoic acids, consisting of 4 to 12 carbon atoms, and (R…
Novel perfluorocyclopentene-derived metallic complexes exhibit pronounced photochromic properties that can form the basis of nondestructive read-out models in optical memory devices. The methodology is described, discussed, and illustrated here by a scheme that represents the interconversion between the open form and…
We report a first-principles description of the induced wake potential and density in real solids. The linear-response formalism is used to obtain the potential and density induced by an external charge penetrating through an inhomogeneous periodic system. The linear dynamical response of the system is evaluated in th…
An elegant and flexible synthesis of pyrene-based dyads bearing ruthenium or osmium chromophoric moieties connected through a single C≡C bond or a Pt(C≡C)2 spacer is described (see picture). Photophysical properties reveal that the two Ru-based units enter into reversible triplet energy transfer with the appended pyre…
Diatom cell walls are regarded as a paradigm for controlled production of nanostructured silica, but the mechanisms allowing biosilicification to proceed at ambient temperature at high rates have remained enigmatic. A set of polycationic peptides (called silaffins) isolated from diatom cell walls were shown to generat…
Masses of single-walled carbon nanotubes (SWNTs) with a large mean diameter of about 1.85 nanometers, synthesized by a semicontinuous hydrogen arc discharge method, were employed for hydrogen adsorption experiments in their as-prepared and pretreated states. A hydrogen storage capacity of 4.2 weight percent, or a hydr…
ADVERTISEMENT RETURN TO ISSUEPREVNoteNEXTReversible Cell Aggregation Induced by Specific Ligand−Receptor CouplingWolfgang MeierView Author Information Institut für Physikalische Chemie, Departement Chemie, Universität Basel, Klingelbergstrasse 80, CH-4056 Basel, Switzerland Cite this: Langmuir 2000, 16, 3, 1457–1459Pu…
Recently, a number of research groups have found that dendrimers are effective templates for the synthesis of inorganic nanomaterials (Sooklal, K.; Hanus, L. H.; Ploehn, H. J.; Murphy, C. J. Adv. Mater . 1998, 10, 1083. Balogh, L.; Tomalia, D. A. J. Am. Chem. Soc. 1998, 120, 7355. Zhao, M.; Sun, L.; Crooks, R. M. J. A…
NMR data have revealed that γ-alumina surfaces do not contain any three-coordinated Al atoms, despite the fact that their presence is expected on the basis of the bulk structure of the material. We report density-functional calculations of γ-alumina (110) surfaces that reveal a massive spontaneous reconstruction of th…
Pathways and generated surface species of adsorption and consequent surface reactions of acetone vapor on characterized silica, alumina, and ∼5 wt % silica−alumina were examined by in-situ infrared (IR) spectroscopy, following degassing at room (RT) and higher temperatures (100−400 °C). For reference and confirmatory…
We report on the synthesis and characterization of rod-shaped PbS nanocrystals dispersed in a polymer film using a functionalized lead(II) salt of the surfactant anion AOT -, Pb(AOT) 2, as the precursor. Essentially all the PbS nanocrystallites prepared using this method have been oriented with their (100) lattice pla…