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。
Tailored microcavities with good size and shape selectivity can be created within long-chain molecular layers assembled in ordered nanoporous channels by using a molecular imprinting technique. The microcavities can be opened or closed by changing the conformations of the molecular chains (see picture).
Porphyrins react readily with organolithium reagents, preferentially in the meso positions. The overall reaction is a nucleophilic substitution and proceeds via initial reaction of the organic nucleophile with a meso carbon yielding an anionic species which is hydrolyzed to a porphodimethene (5,15-dihydroporphyrin), f…
Particles in the nanometer size range are attracting increasing attention with the growth of interest in nanotechnological disciplines. Nanoparticles display fascinating electronic and optical properties as a consequence of their dimensions and they may be easily synthesized from a wide range of materials. The dimensi…
An octanuclear supramolecular assembly comprising La ions in a square antiprismatic array is found in [La8L]. The eight nine-coordinate lanthanum centers are coordinated here by eight rigid C3-symmetric pyrazolone ligands L1 to give an extraordinary ring architecture (see picture).
Ten defined chiral centers are present in the [15]metallacrown-5 complex that is assembled in a one-step reaction from L-tyrosinehydroxamic acid, CuII, and GdIII. Nitrate ions bind selectively to this complex in a cavity of dimension 776 Å3, while chloride binds to the outer face (see picture).
Ein Monooxygenase-Mimetikum: Ein Cytochrom-P-450-Modell mit vier Cyclodextrin-Einheiten an einem Mangan-Porphyrin-Komplex kann mit katalytischem Turnover in eine nichtaktivierte C-H-Bindung ein Sauerstoffatom einschieben (siehe Bild). Die Hydroxylierung eines über zwei Bindungsstellen gebundenen Androstan-3,17-dioldie…
A mimic of monooxygenase enzymes: An artificial cytochrome P-450 with four cyclodextrins linked to a manganese/porphyrin complex can insert an oxygen atom into unactivated C−H bonds with catalytic turnovers (see picture). Hydroxylation of a doubly bound diester of androstane-3,17-diol at C-6 is possible; further oxida…
The controlled construction of a microporous/macroporous materials from diatomaceous earth and a high silica zeolite by a simple method is reported. The picture shows scanning electron microscopy images of the material at two scales (left and center) and the arrangement of the zeolite crystals precipitated onto it (ri…
Coupling agents in wood fiber and polymer composites (WFPC) play a very important role in improving the compatibility and adhesion between polar wood fibers and non-polar polymeric matrices. In this paper, we review coupling agents, pretrcatment, and mixing technology for wood fiber and polymer currently used in the m…
The aggregation of nanocrystals has long been believed to result in disordered solids. In his Perspective, Alivisatos discusses recent evidence that nanocrystals may also form oriented assemblies. He highlights the work by Banfield et al. in this issue, who show that such alignment can also occur in natural systems. T…
The radiation performance of a variety of complex oxides is predicted on the basis of a material's propensity to accommodate lattice point defects. The calculations indicate that a particular class of oxides possessing the fluorite crystal structure should accept radiation-induced defects into their lattices far more…
Particles in the nanometer size range are attracting increasing attention with the growth of interest in nanotechnological disciplines. Nanoparticles display fascinating electronic and optical properties as a consequence of their dimensions and they may be easily synthesized from a wide range of materials. The dimensi…
Certain biopolymers, such as DNA, have a double-stranded twisted structure and frequently exhibit a supercoiled conformation. Over the past decade, extensive conformational analyses of different biopolymers have been performed using atomic force microscopy. In this technique, a necessary step in sample preparation is…
The total vapor pressures of cerium trihalides CeCl 3, CeBr 3, and CeI 3 were measured by the torsion method, and their temperature dependence can be expressed by the following equations over the given temperature ranges: CeCl 3 (s), log( p /kPa) = (12.21 ± 0.20) − (16443 ± 150)K/ T, (955−1070) K; CeBr 3 (s), log( p /…
The poly(3-hydroxybutyrate) (PHB) synthase of Ralstonia eutropha, which was produced by a recombinant strain of Escherichia coli and purified in one step with a methyl-HIC column to a purity of more than 90%, was used to polymerize 3-hydroxypropionyl-CoA (3HPCoA) and to copolymerize 3HPCoA with 3-hydroxybutyryl-CoA (3…
Enzymatic copolymerization of lactones, divinyl esters, and glycols has been performed using lipase as catalyst to produce ester copolymers. The monomers used in this study were 12-, 13-, and 16-membered lactones, divinyl esters of adipic and sebasic acids, and alpha,omega-glycols. Candida antarctica and Pseudomonas c…
Triblock copolymer micelles have been used successfully as templates to form porous, highly uniform, and hollow MoO 3 nanospheres, with their diameter being equivalent to the micellar core size. By use of a combination of static and dynamic light scattering, small-angle X-ray scattering, and wide-angle X-ray diffracti…
In previous studies of capillary condensation of water between mica surfaces using the surface force apparatus (SFA) it has not been possible to obtain agreement with the Kelvin equation. The condensates in these studies exhibited refractive index values larger than that of bulk water and often deposited residues of i…
Organized mesoporous silica (OMS) constitutes new materials with many potential applications. These materials with very well organized pores can be obtained by lowering the pH of precursor systems, i.e., highly alkaline silicate solutions containing cationic surfactants such as cetyltrimethylammonium bromide (CTAB) or…
Reduction of a chiral cerium bisporphyrinate double-decker complex Ce(MOFPP) 2 (MOFPP = 5,15-bis(3,5-dimethoxyphenyl)- 10,20-bis(pentafluorophenyl)porphyrin dianion) with sodium anthracenide in dioxane at 20 °C resulted in acceleration of the porphyrin ligand rotation (= racemization) by a factor of more than 300. Pho…