Materials Literature
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A series of 11 chiral dopants with an atropisomeric core derived from 4,4‘-dihydroxy-2,2‘,6,6‘-tetramethyl-3,3‘-dinitrobiphenyl were synthesized in optically pure form. These compounds were doped into five different smectic C (S C ) liquid crystal hosts to induce a ferroelectric S C * liquid crystal phase, and the red…
High-level ab initio calculations with a variety of G2-based methods have been used to determine the structures and heats of formation of the alkali and alkaline earth oxides and hydroxides (M 2 O, MOH with M = Li, Na, and K; M‘O, M‘(OH) 2 with M‘ = Be, Mg, and Ca). Standard G2 theory, which is normally very reliable…
A new series of side-group liquid-crystal polymers, the poly[ω-(4-methoxybiphenyl-4‘-yloxy)alkyl acrylate]s, has been synthesized in which the spacer length is varied from 3 to 12 methylene units. The thermal behavior of the polymers has been characterized using differential scanning calorimetry and polarized light mi…
A series of merocyanine dye dimers tethered at different sites with spacers ranging from 0 to 5 methylene groups and the corresponding monomer have been synthesized. The formation, structure, and excited-state properties of the consequent merocyanine dye “aggregates” in solutions and in rigid glass have been studied b…
Metallophthalocyanines have been prepared with 18-crown-6 residues at the four peripheral benzo sites (McrPc). Metal centers employed have been H 2 (free base), Zn(II), and Cu(II). In ethanol solution containing potassium acetate, such species incorporate K + cations into the crowns, one K + per crown, and are monomer…
MCM-48 and SBA-1 samples were characterized using powder X-ray diffraction and nitrogen adsorption in a wide range of relative pressures. X-ray diffraction provided direct evidence for the high degree of pore structure ordering for the materials under study. Nitrogen adsorption showed that highly ordered MCM-48 materi…
Self-assembled natural and synthetic clay−polymer films have been prepared by sequential adsorption of poly(diallyldimethylammonium chloride) (PDDA) and clay particles onto mica. The influence of pH, polymer concentration, and clay particle size on the building and roughness of mono- and multicycle depositions was inv…
Semiconductor nanoparticles of cadmium sulfide were synthesized in ammonium perfluoropolyether (PFPE-NH 4 ) stabilized water-in-CO 2 microemulsions. The particle size was tuned by varying the water-to-surfactant molar ratio ( w 0 ): w 0 ratios of 5 and 10 yielded nanocrystals with exciton energies of 3.86 and 3.09 eV,…
Formate dehydrogenase (FDH) from Pseudomonas sp. 101 is a homodimeric enzyme that catalyzes oxidation of formate and the concomitant reduction of NAD + to produce NADH and CO 2 . The dynamic motions and distances between functional groups in the active site of the formate dehydrogenase including the NAD + cofactor and…
Density functional theory with relativistic corrections has been used to calculate the 195 Pt chemical shifts for a series of Pt(II) complexes. Good agreement with experimental values is observed with two different relativistic correction methods. Deconvolution of the parameters leading to the overall shielding of the…
ADVERTISEMENT RETURN TO ISSUEPREVNoteNEXTA Heterogeneous Tungsten Catalyst for Epoxidation of Terpenes and Tungsten-Catalyzed Synthesis of Acid-Sensitive Terpene EpoxidesAída L. Villa de P, Bert F. Sels, Dirk E. De Vos, and Pierre A. JacobsView Author Information Center for Surface Chemistry and Catalysis, Katholieke…
We present the results of quantitative variable-temperature neutron powder diffraction experiments performed on the OSIRIS instrument at the ISIS facility on the pure silica zeolites chabazite and ITQ-4. Chabazite has been found to be one of the most strongly contracting materials known, with a linear expansion coeffi…
Functional devices through self-assembly is the goal of the research presented here. Recent progress in the self-assembly of ultrathin films into layered nanoarchitectures and functional assemblies, such as the chemically modified electrode shown in the Figure, is concentrated on. Other devices examined include enzyme…
We report extensive calculations of the imaginary part of the electron self-energy in the vicinity of the (100) and (111) surfaces of Cu. The quasiparticle self-energy is computed by going beyond a free-electron description of the metal surface, either within the GW approximation of many-body theory or with inclusion,…
A quantitative comparison between the experimental microstructure of a sedimentary rock and three theoretical models for the same rock is presented. The microstructure of the rock sample (Fontainebleau sandstone) was obtained by microtomography. Two of the models are stochastic models based on correlation function rec…
The thermal degradation of poly(methyl methacrylate) (PMMA) has been studied in both pure nitrogen and oxygen-containing atmospheres. The presence of oxygen increases the initial decomposition temperature by 70 °C. The stabilizing effect of oxygen may be explained by forming thermally stable radical species that suppr…
Time-resolved small-angle x-ray scattering was used to measure the radius of gyration of cytochrome c after initiation of folding by a pH jump. Submillisecond time resolution was obtained with a microfabricated diffusional mixer and synchrotron radiation. The results show that the protein first collapses to compact de…
ADVERTISEMENT RETURN TO ISSUEPREVCommunicationNEXTZinc Phosphate with Gigantic Pores of 24 TetrahedraGuo-Yu Yang and Slavi C. SevovView Author Information Department of Chemistry and Biochemistry University of Notre Dame, Notre Dame, Indiana 46556 Cite this: J. Am. Chem. Soc. 1999, 121, 36, 8389–8390Publication Date (…
A method for synthesizing hollow nanoscopic polypyrrole and poly( N -methylpyrrole) capsules is described. The method employs gold nanoparticles as templates for polymer nucleation and growth. Etching the gold leaves a structurally intact hollow polymer capsule with a shell thickness governed by polymerization time (c…
Vanadium oxide nanotubes were obtained as the main product in a sol−gel reaction followed by hydrothermal treatment from vanadium(V) alkoxide precursors and primary amines (C n H 2 n +1 NH 2 with 4 ≤ n ≤ 22) or α,ω-diamines (H 2 N[CH 2 ] n NH 2 with 14 ≤ n ≤ 20). The structure of the nanotubes has been characterized b…