Materials Literature
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Zinc(II) complexes of antipodal beta-tetrasubstituted meso-tetraphenylporphyrin with trifluoromethyl (Zn(TPP(CF(3))(4)) (1a)), bromine (Zn(TPPBr(4)) (2a)), and methyl groups (Zn(TPP(CH(3))(4)) (3a)) were synthesized in order to examine the steric and the electronic effects of trifluoromethyl groups on the macrocycle.…
An extensive search for stable chemisorbed SO 2 configurations on the Pt(111) surface has been performed using first-principles DFT−GGA calculations. The most energetically stable configurations, η 2 -S b,O a and η 3 -S a,O a,O a at fcc sites, where η 2 and η 3 mean that the number of atoms of the adsorbate coordinate…
Abstract Facile syntheses of hyperbranched polyimides were realized by the polymerization of A 2 + BB ′ 2 monomers, 2,2‐bis(3,4‐dicarboxylphenyl) hexafluoropropane dianhydride (6FDA) + 2,4,6‐triaminopyrimidine (TAP), performed by mixing the monomers together in N ‐methylpyrrolidone at 17% w/v concentrations with molar…
We show that the occurrence of pure photoorientation by photoisomerization of azo dye in polymers is influenced by the polymer molecular structure, as well as by the photoisomerization quantum yields and the cis → trans thermal isomerization rate. These findings are rationalized by the study of the photoorientation of…
An efficient and simple method of modification of "inverted" porphyrin is provided by reactions of 5,10,15,20-tetraaryl-2-aza-21-carbaporphyrinatonickel(II) 2 with dihalogenalkanes under basic conditions. The substituents are bound to the internal carbon or external nitrogen of the inverted pyrrole depending on dihalo…
Abstract Epoxy resins containing both phosphorous and silicon were prepared via the fusion process of reacting a phosphorous diol and a silicon diol with a bisphenol‐A‐type epoxy. With various feeding ratios of the reactants, epoxy resins with different phosphorous and silicon contents were obtained. Through curing th…
The thermal evolution, from room temperature up to 300 degrees C, of layered double hydroxides (LDHs) with (Ni, Co) or (Ni, Fe) based slabs and containing intercalated carbonate anions, was studied. A new lamellar phase, exhibiting a 6.5-6.6 A interslab distance, was observed in the 200-260 degrees C temperature range…
Abstract High‐impact polystyrene (HIPS)/nano‐TiO 2 nanocomposites were prepared by surface pretreatment of nano‐TiO 2 with special structure dispersing agent (TAS) and master batch manufacturing technology. The results show that when the nano‐TiO 2 content is 2%, the notched impact strength, tensile strength, and elas…
Recent ultrasonic experiments on single-crystal specimens of the wurtzite $(B4)$ phase of ZnO have shown that, under pressure, this material becomes softer against shear-type acoustic distortions. In the light of these results, we have performed atomistic calculations based on an interatomic pair potential within the…
Two new transition-metal tellurium oxy-chlorides of the general formula Ni 5 (TeO 3 ) 4 X 2 (X = Cl, Br) have been isolated during the investigation of the ternary phase diagram NiO−NiCl 2 −TeO 2 . They crystallize in the monoclinic system, space group C 2/ c, and for the case of Ni 5 (TeO 3 ) 4 Cl 2 the unit cell is…
Peroxidase-catalyzed template-guided polymerization of aniline has been carried out in aqueous micellar solutions of surfactants, such as sodium dodecylbenzenesulfonate, (SDBS), hexadecyltrimethylammonium bromide (CTAB), and polyoxyethylene(10) isooctylphenyl ether (Triton X-100). The properties of these enzymatically…
Accurate density-functional based calculations have been performed on the Co_4(hmp)_4(CH_3OH)_4Cl_4 molecular magnet where hmp is deprotonated hydroxymethyl pyridine. In addition to the experimentally observed staggered geometry, we identify two isomers, referred to as eclipsed and half-staggered/half-eclipsed, that a…
Using a density-functional based algorithm, the full IR and Raman spectra are calculated for the neutral Ti_8C_12 cluster assuming geometries of Th, Td, D2d and C3v symmetry. The Th pentagonal dodecahedron is found to be dynamically unstable. The calculated properties of the relaxed structure having C3v symmetry are f…
We present our density functional results of the geometry, electronic structure and dissociation energy of Ti_8C_12 dimer. We show that as opposed to the currently held view that Ti_8C_12 are highly stable monodispersed clusters, the neutral Ti_8C_12 clusters form covalent bonds and form stable dimers. We determine th…
We show that superexchange interactions in frustrated Jahn-Teller systems with transition metal ions connected by the $90\ifmmode^\circ\else\textdegree\fi{}$ metal-oxygen-metal bonds (e.g., ${\mathrm{N}\mathrm{a}\mathrm{N}\mathrm{i}\mathrm{O}}_{2}$, ${\mathrm{L}\mathrm{i}\mathrm{N}\mathrm{i}\mathrm{O}}_{2}$, and ${\ma…
We study the formation and evolution of coherent islands on lattice mismatched epitaxially strained films. Faceted islands form in films with aniostropic surface tension. Under annealing, these islands ripen until a stable array is formed, with an island density which increases with film thickness. Under deposition, a…
Ab-initio correlation results for an idealized high Tc-compound are compared to density functional (DF) calculations for the same system. It is shown that and why the DF-charge distribution is wrong. The largest deficiency arises for the Cu-d(x2-y2)-occupation, originating from strong atomic correlations but mostly fr…
We report the synthesis and characterization of nanowire−nanoribbon junction arrays of ZnO, which were grown by thermal evaporation of the mixture of ZnO and SnO 2 powders at 1300 °C through a vapor−liquid−solid process. The Sn particles produced by the reduction of SnO 2 act as the catalyst; the structure is formed d…
KMgF/sub 3/ crystals doped with Ce/sup 3+/ have been investigated as a new material for dosimetry of ionizing radiation. Earlier researches have shown their thermoluminescence (TL) properties. The present work shows that this compound can also be read out by optical stimulation with powerful blue or yellow-green light…
The porous silicon (PS) layers on the front surface of n/sup +//p monocrystalline, textured silicon solar cells were investigated with the aim to improve the performance of standard screen-printed silicon solar cells. The application of the PS layer is very promising because simultaneous, antireflection coating and su…