Materials Literature
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In classical enzymology, intermediates and transition states in a catalytic mechanism are usually inferred from a series of biochemical experiments. Here, we derive an enzyme mechanism from true atomic-resolution x-ray structures of reaction intermediates. Two ultra-high resolution structures of wild-type and mutant d…
Novel organic/inorganic hybrid copolymers have been prepared using single site catalysis. Ethylene copolymers incorporating a norbornylene-substituted polyhedral oligomeric silsesquioxane (POSS) macromonomer have been prepared using a metallocene/methylaluminoxane (MAO) cocatalyst system. Isotactic polypropylene-conta…
Red emitting cubic Y 2 O 3:Eu 3+ nanophosphor with an average particle size in the range of 10−20 nm was synthesized using a more facile gel−polymer pyrolysis process. The maximum relative luminescence yield obtained for the nanophosphor prepared with a urea and PVA combination is about 30% in relation to the bulk Y 2…
A series of poly(ethylene oxide) (PEO)/organoclay nanocomposites have been prepared via a solvent casting method. Using three different organoclays modified with the alkylammonium salts, the effect of surfactants on organoclay surfaces in polymer/organoclay nanocomposites was investigated by focusing on two major aspe…
The formation of a new kind of biocompatible film based on poly( l -lysine) and hyaluronic acid (PLL/HA) by alternate deposition of PLL and HA was investigated. Optical waveguide lightmode spectroscopy, streaming potential measurements, atomic force microscopy, and quartz crystal microbalance (QCM) were used to analyz…
The polychalcogenide compound AuCuSe(4) crystallizes in the monoclinic space group P2(1)/m with a = 4.318(2) A, b = 7.447(1) A, c = 8.099(1) A, beta = 93.33(2)(o), and Z = 2. The structure of AuCuSe(4) is a unique three-dimensional framework assembled from formally Au(3+) and Cu(+) ions and Se(3)(2-) and Se(2-) fragme…
We present results of density-functional tight-binding calculations on small titanium carbohedrene clusters (Ti metcars) TimCn with m = 7, 8 and n = 10–14. The structure optimization was performed within our newly developed genetic algorithm, which operates on a given (randomly chosen) population of clusters to genera…
Excited state phthalocyanine complexes comprising (tetra-tert-butylphthalocyaninato)zinc (ZnPc) coordinated by nitroxide radicals have been studied by time-resolved electron paramagnetic resonance (TREPR). Five ZnPc complexes coordinated by an axial ligand containing a nitroxide radical NRX (where X (= 4, 5, 6, 8 or 1…
Infrared optical spectra have been investigated for a charge-transfer complex of tetrathiafulvalene and 2-bromo-3,5,6-trichloro- $p$-benzoquinone, which undergoes a neutral-ionic ( $N\ensuremath{-}I$) transition at ${T}_{c}\phantom{\rule{0ex}{0ex}}=\phantom{\rule{0ex}{0ex}}68\mathrm{K}$. With the decrease of temperatu…
We analyse a simplified dynamical model that emulates the overall process of self-assembly of amphiphilic molecules into micelles under non-equilibrium conditions. The study is motivated by a review of experimental evidence in the literature for the occurrence of bistability and hysteresis in diverse self-assembling m…
The cation distribution in dehydrated NaX was predicted using appropriate interatomic potentials and (N,V,T) simulations, considering the cations as 'guest' particles and the framework as a 'host'; the simulations not only yield the expected different types of sites, but also highlight the cooperative placement of sup…
Five-layered nanocrystals have been prepared that consist of a CdS core covered by a shell of HgS followed by several monolayers of CdS that are covered by again a shell of HgS and an outer cladding layer of CdS. The resulting quantum dots, thus, contain a double well electronic structure. Both HgS wells are either as…
The non-emissive platinum(II)–quaterpyridine complex shows strong photoluminescence at room temperature upon incorporation into Nafion membrane; this complex is stabilized toward photochemical decomposition in Nafion even in the presence of oxygen, and can be used as a sensitizer to generate singlet oxygen to oxidize…
Mesoporosu (MCM-41 type) silica containing surfactant-embedded Congo Red has been prepared and tested against gas phase HCl and ammonia, as well as solutions of ionic species; it is shown that the hybrid (organic-inorganic) material is permeable to both gases and ionic species, and can act as a pH indicator and as a s…
ADVERTISEMENT RETURN TO ISSUEPREVCommunicationNEXTMeta-Activated Nucleophilic Aromatic Substitution Reaction: Poly(biphenylene oxide)s with Trifluoromethyl Pendent Groups via Nitro DisplacementIm Sik Chung and Sang Youl KimView Author Information Center for Advanced Functional Polymers Department of Chemistry and Scho…
The first, single-step, hydrothermal synthetic process has been developed, whereby phase-pure polycrystalline samples of CuAlO2 can be synthesized at low temperature (<215 °C) and pressure (<10 atm). Furthermore, the solid solution CuAl1-yGayO2 (where 0 ≤ y ≤ 1), which has, to date, not been reported, was also synthes…
Hybrid organo-silica materials possessing uniform nanoscale porosity in the super-micropore size range (1.0-2.0 nm diameter) have been prepared using neutral alkylamine and non-ionic alkyl(phenyl)polyethylene oxide surfactants as structure-directing agents.
An Aurivillius phase, Bi(2)SrTa(2)O(9), which consists of perovskite-like slabs and bismuth oxide sheets, was treated with 3 M hydrochloric acid for 72 h, and the resultant product was characterized. Scanning electron microscopy investigation indicated that no morphological change occurred during the acid treatment. X…
New polynuclear molybdenum(VI) and tungsten(VI) complexes with 3-hydroxypicolinic acid (HpicOH) (nBu4N)2[Mo4O12(picOH)2] 1, (nHex4N)2[Mo2O6(picOH)2] 2, (BezPh3P)2[W2O6(picOH)2] 3 (Bez = benzyl) and [M2O5(picOH)2]·nH2O (M = Mo(VI), n = 2 4 or W(VI), n = 8 5) have been prepared. The crystal structures of 1 and 2 were de…
A variety of new cellulose solvents was investigated toward their potential as media for the functionalization of the polyglucane. Thus, mixtures of dimethyl sulfoxide (DMSO)/tetrabutylammonium fluoride trihydrate (TBAF), N-methylmorpholine-N-oxide (NMMNO)/DMSO, melts of LiClO(4).3H(2)O, and aqueous solutions of Ni(tr…