Materials Literature
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A full five-dimensional potential energy surface for the interaction of nitrogen molecules with the (110) surface plane of TiO 2 (rutile) is generated. In a first step, ab initio SCF cluster calculations are performed for various adsorption geometries of N 2 above the TiO 2 (110) surface, which is described by differe…
The triethylamine-assisted metathesis reaction of 2 equiv of Cy7Si7O9(OSiMe3)(OH)2 with 1 equiv of AlCl3 affords the novel anionic aluminosilsesquioxane complex [HNEt3][{Cy7Si7O9(OSiMe3)O2}2Al]·C6H14 (Cy = c-C6H11), 1, which was characterized by IR and 1H, 13C, and 29Si NMR spectroscopy and X-ray diffraction.
The yellow, microcrystalline compound [Cu(pymo)] (Hpymo=2-hydroxypyrimidine) has been characterized with the newly emerging technique of ab initio X-ray powder diffraction. A unique and unprecedented crystal phase containing cyclic oligomers and infinite helical polymers (see picture) of the same monomeric fragment is…
Multiarm star polymers represent a valuable model system for investigating the dynamics of tethered chains, spherical brushes, or grafted colloidal spheres. Because of their topology, the multiarm stars exhibit a nonuniform monomer density distribution leading to a core−shell morphology, which is responsible for their…
An improved synthesis of the phosphazene polymerization precursors, hexachlorocyclotriphosphazene, (NPCl 2 ) 3 ( 1 ), and Cl 3 P NSiMe 3 ( 2 ) is reported. The addition of PCl 5 to N(SiMe 3 ) 3 in methylene chloride at 40 °C produced a mixture of phosphazenes which contained 76% of 1 . However, the addition of N(SiMe…
The local structure of iron in Fe-doped cubic ZrO 2 produced by combustion synthesis was studied by Mössbauer spectroscopy and Fe-K edge extended x-ray absorption fine structure (EXAFS) and X-ray absorption near edge structure (XANES). Iron was found to be in its II oxidation state and to occupy two different sites of…
A series of 2-pyridineketoximes with paraffinic chains of different lengths (CH 3, 1a; C 8 H 17, 1b; C 13 H 27, 1c ) has been synthesized, and their complexes with Cu(II), Co(II), Zn(II), and Ni(II) have been investigated in the cleavage of p -nitrophenyl esters of carboxylic and phosphoric acids in water ( 1a ) or in…
Glucose-flips in a small cycloamylose: the molecular structure of permethylated γ-cyclodextrin, which crystallizes as the dihydrate, is characterized by 180° flips of two diametrically opposed glucose residues. This leads to an elliptical distortion of the molecule and closure of the molecular cavity on one side so th…
ADVERTISEMENT RETURN TO ISSUEPREVCommunicationNEXTAssembly of Organic Molecules on Silicon Surfaces via the Si−N LinkageW. F. Bergerson, J. A. Mulder, R. P. Hsung, and X.-Y. ZhuView Author Information Department of Chemistry, University of Minnesota Minneapolis, Minnesota 55455 Cite this: J. Am. Chem. Soc. 1999, 121,…
An unprecedented coupling reaction of heteroatom-containing tripyrranes leads to the formation of core-modified sapphyrins 1 and 2, which self-assemble in the solid state to form supramolecular ladders. Weak C-H⋅⋅⋅S and C-H⋅⋅⋅Se hydrogen-bonding interactions in addition to C-H⋅⋅⋅N hydrogen bonds are responsible for th…
Blower doors are used to measure the airtightness and air leakage of building envelopes. As existing dwellings in the United States are ventilated primarily through leaks in the building shell (i.e., infiltration) rather than by whole-house mechanical ventilation systems, quantification of airtightness data is critica…
We have studied the critical behaviour in $La_{0.5}Sr_{0.5}CoO_{3}$ near the paramagnetic-ferromagnetic transition temperature. We have analysed our dc magnetisation data near the transition temperature with the help of modified Arrott plots, Kouvel-Fisher method. We have determined the critical temperature $T_c$ and…
This book contains all the necessary information and advice for anyone wishing to obtain electron micrographs showing the most accurate ultrastructural detail in thin sections of any type of biological specimen. The guidelines for the choice of preparative methods are based on an extensive survey of current laboratory…
ADVERTISEMENT RETURN TO ISSUEPREVNoteNEXTLigand-Accelerated Catalysis of the Ullmann Condensation: Application to Hole Conducting TriarylaminesH. Bruce Goodbrand and Nan-Xing HuView Author Information Xerox Research Centre of Canada, 2660 Speakman Drive, Mississauga, Ontario, Canada L5K 2L1 Cite this: J. Org. Chem. 19…
Abstract
The compound Bi 1/2 Ag 1/2 TiO 3 has been synthesized, for the first time, at 14−14.5 GPa and 1000 °C using the uniaxial split sphere anvil type press (USSA-2000). The structure of the quenched powder sample was refined from synchrotron X-ray diffraction data using the Rietveld method. At room temperature, Bi 1/2 Ag 1…
The NH protons of the chlorins (17,18-dihydroporphyrins) and fully conjugated porphyrins can undergo tautomerization between the four central nitrogens. We have investigated the NH tautomerization process of bonellin dimethyl ester by NMR spectroscopy and molecular modeling. In this natural chlorin derivative, the tau…
Sulfur K-edge X-ray absorption spectroscopy (XAS) has been used to investigate the distribution of sulfur types in two whole blood cell samples, in selected subcellular blood fractions, and in cell-free plasma from the tunicate Ascidia ceratodes . Whole blood cells are rich in sulfate, aliphatic sulfonate, and low-val…
Photoisomerization of the azo component in the supramolecular hydrogen-bonded assembly between 4,4‘-azabipyridine and 4-alkyloxybenzoic acid brings about a marked increase in its crystal to liquid crystal phase transition temperature.
It was observed that the photolysis of 4‘-chlorostilbenecarboxylic acid (CSC) in N,N -dimethylformamide (DMF) yielded mainly a syn head-to-head dimer. The molecular alignment in hydrotalcite interlayers has been investigated by electric linear dichroism (ELD) at room temperature in order to clarify the correlation bet…