Materials Literature
按标题、摘要、年份、主题和来源检索公开元数据。结果保留作者、摘要、分类与原始来源链接。
The understanding of space charge effects depends largely on how concurrent phenomena, such as thermal and electrical aging are understood. A model describing thermal and environmental aging of dielectric polymers is discussed. The model essentially is based on the rate theory associated with the name of Eyring. One b…
A docosanuclear metal complex of nanometric size and dendritic shape made of an osmium(ii)-based core and containing 21 ruthenium(ii)-based units in the branches has been prepared. The key building blocks are the [Os(2,3-dpp) 3 ] 2+ ‘complex ligand’, and the [Ru(2,3-Medpp) 2 Cl 2 ] 2+ and [{Ru(bpy) 2 (µ-2,3-dpp)} 2 Ru…
Highly functionalized silsesquioxanes and spherosilicates of the formulae [(RCHCH) 8 Si 8 O 12 ] and [(RCHCHSiMe 2 -O) 8 Si 8 O 12 ] can be prepared by cross-metathesisreactions of alkenes with readily available vinyl-substituted silsesquioxane and spherosilicate frameworks, [(vinyl) 8 Si 8 O 12 ] 1 and [(vinylSiMe 2…
The synthesis and single-crystal X-ray structure analysis of the unusual Mo/V polyoxometalate compound Na 0.5 K 6.5 [Mo VI 8 V IV 4 O 36 (V V O 4 )(V IV O) 2 ]·12.5H 2 O which contains capped α-Keggin fragments linked to a chain is reported; this chain is an interesting object for magnetochemists and can be considered…
Synchrotron X-ray diffraction patterns for highly crystalline MCM-41 a mesoporous silicate molecular sieve are presented. The form factor observed in seven orders of diffraction is used to show the existence of a two-layer wall structure, with a narrower mesopore than previously assumed, and much void space in the wal…
Self-assembly and non-covalent interactions are employed for the preparation of a new family of cationic artificial supramolecular multiporphyrin aggregates incorporating Pd II and Pt II bisphosphane complexes as auxiliaries.
It has recently been demonstrated that hexagonal mesoporous silica films can be grown at mica/water interfaces. In this report it is established that the films can also be synthesized on cleaved pyrolytic graphite. Diffraction and microscopy studies of the growth, structure and form of the films indicate that the chan…
The application of combinatorial methods to the synthesis and characterization of novel materials is described for the case of solution‐phase synthesis of phosphors based on rare‐earth‐activated refractory metal oxides. A scanning multiinkjet system is shown to be suitable for the fabrication of a liberry such as (La…
The ionic and n‐type conductivities of ceria‐based electrolytes doped with gadolinium (10 and 20 cation %) or gadolinium and praseodymium (2% Pr and 18% Gd) were studied by impedance spectroscopy in air, between 573 and 1273 K, and by constant frequency (10 kHz) conductivity measurements as a function of the oxygen pa…
Active catalysts for the epoxidation of alkenes by tert-butyl hydroperoxide are provided by silasesquioxane titanium(IV) derivatives; a non-leaching catalyst, not prone to irreversible protic cleavage of its siloxy functions by the oxidizing agent, contains a terdentate silasesquioxane ligand.
By synthesising and structurally characterising new soluble titanosilsesquioxanes, and by following the dynamics of epoxidation of cyclohexene in their presence, the tripodally anchored TiIV active sites in Ti–SiO2 heterogeneous catalysts are modelled structurally and catalytically.
Ordered ultrafine platinum particles are expected to have properties differing from those of isolated particles, however, few measurements have been made because of the difficulty of producing monodispersed Pt particles. A method is reported for controlling the size and size distribution of polymer‐protected ultrafine…
The optical properties of rare-earth organic complexes have been studied because of their possible application to polymer optical fibers and waveguides. Er3+, Nd3+, and Sm3+ ions are encapsulated in tetrakis(benzoyltrifluoroacetonate) and tetrakis(dibenzoylmethide) chelates, and their radiative properties are evaluate…
The solid-state shape, size, and intermolecular packing of a fifth-generation dendritic macromolecule were determined by a combination of site-specific stable-isotope-labeling, rotational-echo double-resonance (REDOR) NMR and distance-constrained molecular dynamics simulations. REDOR experiments measured dipolar coupl…
Highly crystalline MCM-41 with a very narrow pore-size distribution (FWHM=1.5 Å), high surface area (1185 m2 g -1 ), large grain size and thick channel walls (ca. 17 Å) was prepared in alkali-free media. The properties of the product depend on the source and concentration of the reactants, the gel aging time, the temp…
Molecular or polymeric π-electron donors based on the association of tetrathiafulvalene (TTF) with linear π-conjugated systems are reviewed. Two main classes of materials are considered, namely electrogenerated polymers, either conjugated or not, and linearly extended TTF analogues built by insertion of different π-co…
Silanation of the internal pore surface of the mesoporous molecular sieve MCM-41 (40 Å) has yielded ethylenediamine (ED), diethylenetriamine (DET), and ethylenediaminetriacetic acid salt (EDT) functionalized sites. These grafted ligands were used for the preparation of cobalt(II) complexes covalently bound to the MCM-…
Superlattices of self‐assembled Ag nanocrystals have been prepared and the structure analyzed using a combination of techniques. It is shown that the supercrystals are hexagonally close‐packed, attributed to a high proportion of icosahedral and decahedral particles. The Figure (a TEM image of the Ag supercrystals) ill…
Testosterone (17β-hydroxy-4-androsten-3-one) was studied by the semiempirical AM1 and PM3 and ab initio STO-3G*, 3–21G*, and 6–31G* methods. The goals were to compare those methods and to know the electronic structure of the hormone. Full geometry optimization was performed, and two crystal conformers (T1 and T2), and…
Abstract Polyamide, polyester and polyoxymethylene having presently a worldwide sales volume of 2,4 million tons a year are important engineering thermoplastics. Based on their special property profiles they are mainly used in the automotive and electronic industry for high performance functional parts. This contribut…