Materials Literature
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Molecular dynamics simulations of a model main-chain liquid crystalline polymer (LCP) and of a low molecular weight analogue have been carried out using an efficient parallel algorithm. A main-chain LCP is formed with the help of Gay−Berne mesogenic units connected to each other through flexible methylene spacers. We…
Liquid-crystalline side-chain polymeric complexes with well-defined structures have been obtained by supramolecular assembly of poly(acrylic acid) and mesogenic compounds containing imidazolyl-terminated alkyl chains. Hydrogen bonds formed between carboxylic acid and N -(alkyl)imidazole moieties can function as molecu…
ADVERTISEMENT RETURN TO ISSUEPREVNoteNEXTChiral H- and J-Type Aggregates of meso-Tetrakis(4-sulfonatophenyl)porphine on α-Helical Polyglutamic Acid Induced by Cationic PorphyrinsRoberto Purrello, Luigi Monsu' Scolaro, Emanuele Bellacchio, Sergio Gurrieri, and Andrea RomeoView Author Information Dipartimento di Scienze…
Novelties and surprises in the chemistry of metal isocyanides: The synthesis and structure determination of homoleptic isocyanide metalates [M(CNXyl)m]− (M=Co, m=4; M=Mn, m=5; Xyl=2,6-Me2C6H3) indicate that we need to revise our understanding of transition metal–isocyanide interactions. Further investigations will be…
Unprecedented stabilization of the copper(I) oxidation state is demonstrated for the complex cation [Cu(bfp)2]+ (1) due to the steric and electronic effects of the CF3 groups (E1/2(CuII/CuI)=+1.55 V vs. SCE). The redox existence range of the copper(I) species is remarkably high at 2.77 V. It is emissive in solution at…
Carboxylate and ammonium functionalities-32 of each-facilitate electrostatic interaction between oppositely charged dendrimer electrolytes and porphyrin cores, which leads in protic media to a supramolecular, fluorescence-active aggregate of two chromophores that communicate and have a predictable topology (see drawin…
We have developed new transparent photochromic hybrid organic−inorganic materials in which the photochromic group belongs to the polymer network. These materials involving chemically bonded dithienylethene derivatives were prepared by the sol−gel process in the form of thin films a few microns thick. The thickness and…
We give in this letter a set of general rules which allow the prediction of the value of the glass transition temperature $T_g$ in network glasses. Starting from the Gibbs-Di Marzio law which gives a very general relationship between this temperature and the average coordination number of a system, we explain how to c…
The light-induced insulator-metal transition in the "colossal magnetoresistance" compound Pr0.7Ca0.3MnO3 is shown to generate a well-localized conducting path while the bulk of the sample remains insulating. The path can be visualized through a change of reflectivity that accompanies the phase transition. Its visibili…
The foaming of polystyrene using supercritical (SC) CO 2 has been studied to better understand the microcellular foaming process, as we plan future studies that involve the creation of composite microcellular foams. Rapid decompression of SC CO 2 -saturated polystyrene at sufficiently high temperatures (above the depr…
Independent one-, two-, and even three-dimensional nets interpenetrate each other in many solid-state structures of polymeric, hydrogen-bonded nets and coordination polymers. For example, the interpenetration of the adamantane units of two diamondlike nets is shown on the right. A detailed and systematic examination o…
Surface functionalization of poly(ethylene- alt -maleic anhydride) copolymer films with trifluoroethylamine and amine terminated polyethers (Jeffamines) to form amide linkages has been shown to proceed to high levels of conversion.
We have studied by atomic force microscopy (AFM, topographical imaging) the evolution of a single PEEK spherulite in a thin film during isothermal cold-crystallization and upon subsequent reheating to increasingly higher temperatures. To open the spherulitic microstructure, we added 30% w/w of an amorphous diluent (po…
Methylglyoxal synthase provides bacteria with an alternative to triosephosphate isomerase for metabolizing dihydroxyacetone phosphate (DHAP). In the present studies, the methylglyoxal synthase gene in Escherichia coli has been cloned and sequenced. The identified open reading frame (ORF) codes for a polypeptide of 152…
The electronic properties of a modified (Co, Fe) Prussian blue compound, which exhibits interesting photoinduced magnetic properties, are analyzed. For band structure calculations we set realistic models (for the ground and excited states) that involve interstitial potassium ions, crystal water, and lattice defects. T…
The evolution of H 2 from diamond cathodes according to the proposed mechanism H + (aq) + ⪫C−H + e - → H 2 + ⪫C • is treated with ab initio quantum mechanics. The solvated proton and diamond surface C−H bond are modeled with molecular clusters, and the electron is introduced at selected potentials by using a remote do…
Large pore MCM-41 silica with the pore diameter of 5.0 nm was chemically modified by bonding monomeric-type ligands, such as trimethylsilyl, butyldimethylsilyl, and octyldimethylsilyl, as well as polymeric-type 3-aminopropylsilyl, (hexanoyl-3-aminopropyl)silyl, and octylsilyl ligands. The obtained materials were chara…
The superelastic behavior of shape memory alloys (SMAs) provides a stress-strain relation which is characterized by large hysteresis, superelastic effect, large ductility and variation of the material properties at different level of strain. Those properties can be effectively used in a design of SMA dampers for vibra…
This work reports the relative importance of the interactions provided by three catalytic residues to individual steps in the mechanism of citrate synthase. When the side chains of any of the residues (H320, D375, and H274) are mutated, the data indicate that they are involved in the stabilization of one or more of th…
The static and frequency-dependent first hyperpolarizabilities (β) of Reichardt's betaine dye and two simplest pyridinium- N -phenoxide betaines were computed in the gas phase and in aqueous solution. The sum-over-state formalism was used to calculate individual components of the β-tensors. The solvent effect was incl…