Materials Literature
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Three significant modifications to existing methods for the preparation of the important 5,10,15,20-tetrakisarylporphyrins have improved isolated yields, simplified work-up and made large-scale synthesis feasible.Two teuakisalkylporphyrins were also produced.A two-stage approach using hydrogen peroxide in acetic acid…
The heterometallic complex (NH(3))(2)YbFe(CO)(4) was prepared from the reduction of Fe(3)(CO)(12) by Yb in liquid ammonia. Ammonia was displaced from (NH(3))(2)YbFe(CO)(4) by acetonitrile in acetonitrile solution, and the crystalline compounds {[(CH(3)CN)(3)YbFe(CO)(4))](2).CH(3)CN}(infinity) and [(CH(3)CN)(3)YbFe(CO)…
Control over the shapes of biologically formed crystals is generally not well understood. We have studied the morphogenesis of the different-shaped calcareous sponge spicules using high-resolution synchrotron X-ray diffraction. We show that a remarkable correlation exists between the distribution of defects within spi…
Described here is a QSPR equation for calculating glass transition temperatures for acrylate and methacrylate polymers, especially those with bulky ester substituents. This approach is based on molecular mechanics calculations and exclusively involves a force field to describe a particular polymer system; i.e., no gro…
Conventional quenching methods were used to prepare (50-x/2)Na 2 O.xBi 2 O 3 . (50-x/2) P 2 O 5 system phosphate glasses for x≤16.0. The glass structure was then analysed with infrared and 31 P MAS NMR spectroscopy. The main phosphate species formed by the depolymerisation of the sodium metaphosphate chains by Bi 2 O…
We examine the surface segregation behavior of binary polymer blends with architecturally asymmetric components. Particular attention is given to molten blends containing linear and branched polymers composed of the same type of monomer. If the branches are sufficiently long and the branch points (joints) dilute, we a…
In an attempt to improve on the properties of PEDOT (poly(3,4-ethylenedioxythiophene)) as a stable, conducting, and transparent coating we synthesized four different alkoxy-substituted poly(thienylene−vinylene)s, 1 − 4, using the Stille coupling reaction. The oligomers and polymers obtained were characterized and thei…
An all-aromatic thermosetting copolyester has been prepared using hydroquinone, hydroxybenzoic acid, isophthalic acid, trimesic acid, and/or 1,3,5-triacetoxybenzene as key building blocks. The preparation and characterization of these materials are described. Cured resins based on these structures exhibit thermal stab…
In this paper, the authors deal with the effects of inverter characteristics on iron losses in induction motors fed by pulsewidth modulation (PWM) controlled power converters. Laboratory tests based on no-load input power measurements were carried out and in order to avoid the influence of mechanical losses and rotor…
ADVERTISEMENT RETURN TO ISSUEPREVCommunicationNEXTMolecular UmbrellasVaclav Janout, Marion Lanier, and Steven L. RegenView Author Information Department of Chemistry and Zettlemoyer Center for Surface Studies Lehigh University, Bethlehem, Pennsylvania 18015 Cite this: J. Am. Chem. Soc. 1996, 118, 6, 1573–1574Publicati…
Second-order hyperpolarizabilities (β), electron distribution, dipole moment, and excitation energy together with oscillator strength of stilbazolium cations have been investigated by a semiempirical calculation with PM3 parametrization of the MNDO Hamiltonian. Since stilbazoliums were found to generally have several…
We have synthesized amorphous sp 2 -bonded carbon nitrides at high pressure. A precursor composed of carbon and nitrogen, tetracyanoethylene, was compressed in a diamond anvil cell and laser heated to approximately 2000 °C. Transmission electron microscopy, electron diffraction, electron energy loss spectroscopy, and…
High tensile ductility may be achieved in metallic alloys over a limited range of strain rates at elevated temperatures when the grain size is very small (typically less than ∼10μm). These superplastic materials are often suitable for industrial forming operations. This paper considers the possibility of attaining a s…
A series of monofunctionalized triphenylene-based discotic liquid crystals were synthesized starting from 2-hydroxy-3,6,7,10,11-pentakis(pentyloxy)triphenylene. These compounds are unique in that they possess a single electron-withdrawing group (and consequently a large dipole moment) connected directly to the polyaro…
ADVERTISEMENT RETURN TO ISSUEPREVCommunicationNEXTSynthesis of Tetraphenyltetraacenaphthoporphyrin: A New Highly Conjugated Porphyrin System with Remarkably Red-Shifted Electronic Absorption SpectraTimothy D. Lash and Pushpa ChandrasekarView Author Information Department of Chemistry Illinois State University Normal,…
Mechanism of the oxidative dimerization of DTF (dithiafulvenes) to form TTF vinylogues (tetrathiafulvalenes) has been investigated by cyclic voltammetry at low and high scan rates for a series of substituted DTF. It involves first the formation of the cation radical which couples to form the protonated dication. This…
In this study, the authors investigated the tribological performance of diamond and diamondlike carbon (DLC) films as a function of temperature. Both films were deposited on silicon carbide (SiC) by microwave plasma chemical vapor deposition and ion-beam deposition processes. Tribological tests were performed on a rec…
The dielectric relaxation processes of a ferroelectric liquid crystal material with a first order phase transition (chiral-nematic to smectic-${\mathit{C}}^{\mathrm{*}}$) have been investigated using thin, gold coated electrode cells in the frequency range of 10 Hz to 13 MHz. The results have been reported for planar…
A new phenyltin tungstosilicate derivative, [(PhSnOH(2))(2)(gamma-SiW(10)O(36))(2)](10)(-) (1), has been prepared by reaction of phenyltin trichloride with K(8)[gamma-SiW(10)O(36)].xH(2)O. The new heteropolyanion was characterized by elemental analysis, infrared spectroscopy, multinuclear NMR, and X-ray crystallograph…
We have prepared Lactobacillus casei dihydrofolate reductase containing biosynthetically incorporated (2 S,4 S )-5-fluoroleucine ([5-F]-Leu DHFR) and have obtained its 1 H and 19 F NMR spectra at 9.4 Tesla. The 19 F spectrum of [5-F]-Leu DHFR showed 12 fairly sharp peaks (one containing two overlapped signals) for the…