Materials Literature
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Raman spectra of oligo-p-phenylenes, oligorylenes, and oligoacenes of different chain lengths have been obtained in the solid state and in solution. Among the properties studied, particular attention is devoted to frequency and intensity dispersion of the Raman bands with increasing conjugation length and to the vibra…
1,7-dithia (12-crown-4)-bridged phthalocyanine network polymers were prepared from tetracyanodibenzo-[1,7-dithia(12-crown-4)]. In addition, the synthesis of two 1,7-dithia (12-crown-4) linked peripherally octa-substituted dimeric phthalocyanines, which contain a combination of hexakis(alkylthia) side chains, is descri…
New discusses the ways in which Canadian writing, through images of land and space, expresses various assumptions about social values. In addition to wide range of literary texts, he also draws upon geography, the social sciences, and the visual arts.
Reaction of 3-(2-pyridyl)pyrazole with POBr 3 in toluene–NEt 3 afforded not the expected tris(pyrazolyl)phosphine oxide but the partially hydrolysed compound bis[3-(2-pyridyl)pyrazol-1-yl]phosphinate (as its triethylammonium salt). This compound has two potentially chelating N,N′-bidentate arms linked by an apical PO…
Molecule‐based ferromagnets that exhibit strong second‐harmonic generation (SHG) are presented here for the first time. The strategy for producing such materials—replace the “innocent” bulky cations (C) in the C[M′M(ox) 3 ] family of bimetallic magnets (M′ is e.g. Mn and M = Cr III or Fe III ; the Figure shows the str…
The sonochemical formation of Q-state CdS colloids and the dissolution of larger colloidal CdS particles are described. In systems containing mercaptopropionic acid, the action of ultrasound produces H 2 S and in the presence of Cd 2+ (aq) ions, colloidal CdS is formed. The mechanism for the production of H 2 S appear…
Molecular charge-transfer salts that consist of alternating layers of organic donor molecules and inorganic anions offer the opportunity of bringing together in the same crystal lattice conduction electrons localised on the donor sublattice and magnetic moments localised on the inorganic anions. A wide range of such c…
The amorphous phase formed on melting the crystalline polymer electrolyte PEO 3 :LiCF 3 SO 3 has a short-range structure in which all of the lithium ions are located within the poly(ethylene oxide) helix.
Solution scattering curves evaluated from the crystal structures of the T and R states of the allosteric enzyme aspartate transcarbamylase from Escherichia coli were compared with the experimental x-ray scattering patterns. Whereas the scattering from the crystal structure of the T state agrees with the experiment, la…
Giant magnetoresistance, and spin‐, charge‐, and orbital‐ordering are some of the properties displayed by manganates that make these materials of interest in magnetic recording, sensor, and actuator technology. New and significant results on the giant magnetoresistance found in films as well as polycrystalline and sin…
The crystal structures of two CN - bridged bimetallic copper(II)−chromiun(III) complexes, [{(Cu(dien)) 2 Cr(CN) 6 } n ][Cu(dien)(H 2 O)Cr(CN) 6 ] n ·4 n H 2 O ( 1 ) and [(Cu(edma)) 3 Cr(CN) 6 ] ( 2 ) (where dien and edma are diethylenetriamine and ethylenediaminemonoacetate respectively), have been determined. Complex…
The characteristics of infrared (IR) microbolometer arrays utilizing semiconducting YBaCuO and operating at room temperature are presented. Surface-micromachined structures in the form of 1/spl times/10 arrays of pixel size 40 /spl mu/m/spl times/40 /spl mu/m and 60 /spl mu/m/spl times/60 /spl mu/m as well as single p…
Кристаллические структуры в плазме с сильным взаимодействием макрочастиц, Нефедов А.П., Петров О.Ф., Фортов В.Е.
Equilibrium O 2 and CO binding behaviour of two dendritic iron(II) porphyrin systems is reported.
The acid properties of Al-, Ga- and Fe-substituted mesoporous silicates have been investigated using ammonia as a probe molecule. Substitution leads to the formation of Brønsted and Lewis acid sites of different type and strength. The IR spectra of ammonia-loaded samples show bending vibration bands near 1450 cm -1 (a…
The production of triplet states in basic solution of tetrakis(tetrasulfonated-phenyl)porphyrin (TPPS 4 ) is accompanied by a contraction of (10 ± 3) mL/mol as determined by laser-induced optoacoustic spectroscopy (LIOAS) at different temperatures. The contraction is reverted as the triplet decays. The volume changes…
The mesoporous silicate, MCM-41 is modified by grafting the chiral alkene polymerisation catalyst rac-ethenebis(indenyl)zirconium dichloride onto the surfaces of the mesopore and used to produce highly isotactic polypropene with a unique spherulite morphology.
Adsorption of nitrogen oxides (NO, NO2) and their coadsorption with oxygen on Co2+/SiO2 samples has been investigated by IR spectroscopy with a view to elucidating the mechanism of selective catalytic reduction (SCR) of NOx with hydrocarbons. A Co2+/SiO2 sample synthesized by ion exchange is characterized by a highly…
A facile divergent synthesis of monodisperse polyphenylene dendrimers having diameters of 21–55 Å is presented. These nanoparticles have been preparedvia a [2+4]cycloaddition–deprotection sequence using an excess of tetraphenylcyclopentadienone 1a as monomer and the tetraethynylbiphenyl 2 as core. Due to the dense pac…
Benzyl aryl ether dendrimers with azobenzene central linkers undergo reversible cis/trans isomerization of the azobenzene moiety upon exposure to ultraviolet light.