Materials Literature
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High specific surface areas and adjustable pore sizes are outstanding characteristics of nanoporous silicon nitride based materials prepared by using oxygen-free molecular precursors in a novel template-assisted sol-gel approach. The nitrides represent a new class of shape-selective superbase catalysts (see, for examp…
The tripodal ligand (alpha,alpha',alpha' 'nitrilotri(6-methyl-2-pyridinecarboxylic acid)) (H(3)tpaa) forms a Gd(III) complex which has a relaxivity (r(1p) = 13.3 mM(-1) s(-1) at 25 degrees C and at 60 MHz) remarkably higher than those of the currently clinically used contrast agents based on octacoordinate polyaminoca…
A bis-chelating ligand (L1), made of two 7-(p-anisyl)-1,10-phenanthroline (phen) subunits connected with a p-(CH(2))(2)C(6)H(4)(CH(2))(2) spacer through their 4 positions, has been prepared, using Skraup syntheses and reaction of the anion of 4-methyl-7-anisyl-1,10-phenanthroline with alpha,alpha'-dibromo-p-xylene. It…
The self-complementary coordination unit [Cu(H2sabhea)]+ with a pentadentate amino alcohol as ligand enables the synthesis of the first triply hydrogen-bridged dinuclear copper(II) complex (see picture). Proton transfer allows the reversible transformation between this triply and the corresponding doubly hydrogen-brid…
The structure of (1- x )[Pb(Mg 1/3 Nb 2/3 )O 3 ]- x PbTiO 3 is tetragonal and rhombohedral for x ⩾0.35 and x ⩽0.30, respectively. The intrinsic width of the morphotropic phase boundary region (0.30< x <0.35) is an order of magnitude smaller than hitherto believed. The structure of the morphotropic phase for x = 0.34 i…
Through a simple gas reaction, single-crystalline β-Ga 2 O 3 nanoribbons, nanosheets and nanowires were synthesized on a large scale at 700 °C. They were characterized by means of x-ray powder diffraction (XRD), field emission scanning electron microscopy (FE-SEM), energy-dispersive x-ray spectroscopy (EDS), transmiss…
Self-aggregation of water-soluble pyridinium-substituted porphyrins with functionalized calixarenes leads to well-defined pH-tunable stoichiometries. Two assemblies with different porphyrin:calixarene ratios that crystallized at pH 2 and 6 have been structurally characterized. The Job plots of Soret band broadenings i…
ADVERTISEMENT RETURN TO ISSUEPREVCommunicationNEXTFirst Unequivocal Observation of the Whole Bell-Shaped Energy Gap Law in Intramolecular Charge Separation from S2 Excited State of Directly Linked Porphyrin−Imide Dyads and Its Solvent-Polarity DependenciesNoboru Mataga, Haik Chosrowjan, Yutaka Shibata, Naoya Yoshida,…
complex of an N-alkyloxysalicylidenyl-N'-ethyl-N-ethylenediamine ligand, shown as a computer model in the picture, is the first compound in which spin-crossover (SC) and liquid-crystalline (LC) properties coexist. This synergy should allow the magnetic and optical properties of SC compounds to be combined with the sen…
ADVERTISEMENT RETURN TO ISSUEPREVNoteNEXTSelective Aerobic Oxidation of Alcohols with a Combination of a Polyoxometalate and Nitroxyl Radical as CatalystsRevital Ben-Daniel, Paul Alsters, and Ronny NeumannView Author Information Department of Organic Chemistry, Weizmann Institute of Science, Israel, 76100, and DSM Res…
The transparent, double bridged-(R)-spiral three-dimensional polymeric complex K0.4[Cr(CN)6][Mn(S)-pn](S)-pnH0.6 ((S)-pn=(S)-1,2-diaminopropane) has been synthesized and characterized (see X-ray structure; Cr: brown, Mn: red, C: gray, N: blue, K: green). Magnetic measurements on the complex show that the MnII and CrII…
This paper reports the application of ligand-field electronic absorption spectroscopy to probe Co(2+) dopant ions in diluted magnetic semiconductor quantum dots. It is found that standard inverted micelle coprecipitation methods for preparing Co(2+)-doped CdS (Co(2+):CdS) quantum dots yield dopant ions predominantly b…
Enforced ligand dissociation as a result of steric interactions between ZnII porphyrin units and the N atoms of pyridylphosphane ligands determines the catalytic properties of the encapsulated transition metal complexes (see picture). These assemblies show increased catalytic activity in the palladium-catalyzed Heck r…
Lanthanide complexes of europium and terbium ions with hydrogen phthalate [Eu(Hphth) 3 and Tb(Hphth) 3, respectively, Hphth = hydrogen phthalate] were incorporated into poly(vinyl pyrrolidone) (PVP) matrix. Transmission electron microscopy (TEM) results showed that the lanthanide complexes, with a mean diameter about…
The phase behavior of a set of high hard block content (50% to 100% hard segment by weight) linear thermoplastic polyurethanes has been investigated mainly via differential scanning calorimetry (DSC). The soft segment was based on a polypropylene oxide polyol end-capped with ethylene oxide and the hard segment on a 4,…
The uniaxial elastic-plastic deformation process is considered. Mathematical model of this process was built. According to this model all stable static states form the lattice, which is called the delta-lattice.
The kp method is used to analyze the problem of intervalley Γ-X_z interaction of conduction band states in the (001) lattice-matched III-V semiconductor heterostructures. A convenient basis for expansion of the wave function is systematically selected and a multiband system of equations is derived for the envelope fun…
In this review article we briefly summarize the main experimental properties of (III,Mn)V ferromagnets and outline several different but related approaches that have been explored in an effort to gain insight into these materials. The main body of the paper deals with the development of the semi-phenomenological model…
In this paper we review the latest achievements of density functional theory in understanding the physics of diluted magnetic semiconductors. We focus on transition metal doped III-V semiconductors, which show spontaneous ferromagnetic order at relatively high temperature and good structural compatibility with existin…
Mixed-valence perovskite manganites (Re 1- x A x MnO 3 where Re = rare earth, A = alkaline earth) provide a unique opportunity to study the relationships between the structure and the magnetotransport properties due to an interplay among charge carriers, magnetic coupling, orbital ordering and structural distortion. T…