The mineralization of CO32− ions on chitin- or chitosan- metal composite beads in water

The following dry composite beads (diameter 1.0-1-2 mm) were prepared: chitin-CaCO₃, chitosan-CaCl₂. chitosan-CuCl₂, partially N-acetylated chitosan-CuCl₂, chitosan-CuSO₄, chitosan-Fe₃O₄, chitin-SiO₂. Each of chitosan-CuCl₂, chitosan-CuSO₄ and chitin-CaCl₂ composite beads was treated in aqueous K₂CO₃ at room temperature to afford a mixture of metal carbonates and hydroxides on chitin or chitosan chain.     

New methods and reagents in organic synthesis, 40. Amination of aromatic and heteroaromatic organometallics using diphenyl phosphorazidate (DPPA)

Amination of aromatic and heteroaromatic organometallics is efficiently achieved by sequential treatment with diphenyl phosphorazidate (DPPA) and sodium bis(2-methoxyethoxy)aluminum hydride in a one-pot process.     

A new example of linear disiloxane: Synthesis and X-ray crystal structure of bis(2-silolyl)tetramethyldisiloxane

Bis(2-silolyl)tetramethyldisiloxane has been obtained by an attempted Wurtz-type coupling of (2-silolyl)dimethylsilyl chloride using sodium metal, and its linear Si–O–Si geometry has been demonstrated by X-ray crystallography.Dedicated to Professor E. Lukevics on the occasion of his 60th birthday.Institute for Chemical Research, Kyoto University, Uji, Kyoto 611, Japan. Rigaku Corporation, Akishima, Tokyo 196, Japan. Published in Khimiya Geterotsiklicheskikh Soedinenii, No. 2, pp. 180–185, February, 1997.     

Seeded Polymerization through the Interplay of Folding and Aggregation of an Amino‐Acid‐based Diamide

Amino acid based diamides are widely used as a substructure in supramolecular polymers and are also key components of polypeptides that help to understand protein folding. The interplay of folding and aggregation of a diamide was used to achieve seed‐initiated supramolecular polymerization. For that purpose, a pyrene‐substituted diamide was synthesized in which pyrene is used as a tracer to monitor the supramolecular polymerization. Thermodynamics and time‐dependent studies revealed that the folding of the diamide moiety, via the formation of intramolecular hydrogen bonds, effectively prevents a spontaneous nucleation that leads to supramolecular polymerization. Under such out‐of‐equilibrium conditions, the addition of seeds successfully initiates the supramolecular polymerization. These results demonstrate the utility of such amino acid based diamides in programmable supramolecular polymerizations.     

Voltammetric response of phenylboronic acid monolayer-modified gold electrode to sugars.

The surface of a gold (Au) disk electrode was modified with a self-assembled monolayer consisting of phenylboronic acid moiety to fabricate a voltammetric sensor sensitive to sugars. The modified Au electrode exhibited a voltammetric response to sugars in the presence of Fe(CN)6(3-) ion in the sample solution at neutral pH. The peak current of the cyclic voltammograms decreased depending on the type and concentration of sugars. The dynamic range of the electrode is 3 - 100 mM for glucose and mannose and 1 - 30 mM for fructose. The sugar sensor can be used repeatedly after rinsing in 10 mM acetate buffer (pH 4.5).     

Plasma Enhanced Chemical Vapor Deposition of Fluorinated Amorphous Carbon Thin Films from Tetrafluoroethylene and Tetraisocyanatesilane

Fluorinated amorphous carbon films were prepared from tetrafluoroethylene (TFE; C₂F₄) and tetraisocyanatesilane (TICS; Si(NCO)₄) using an RF plasma enhanced chemical vapor deposition method for the purpose of application to inter layer low permittivity films used in large scale integrated circuits. Structure of the deposited films was investigated by X-ray photoelectron spectroscopy and Fourier transform infrared spectroscopy. Adhesion characteristics were examined by a tape-peel method. Permittivity of the films was investigated from capacitance measurement on metal-insulator-semiconductor structure. The structural analysis revealed that the deposited films contained imide-like group in spite of the fact that TICS molecules contained isocyanate group . The films deposited under the flow ratio TICS/(TFE + TICS) = 70% showed permittivity of 2.3, good adhesion on silicon substrates, and higher thermal stability than the films deposited without TICS.     

Total synthesis of amauromine

Total synthesis of amauromine ($\text{1}$), a novel alkaloid possessing two reversed prenyl groups in its molecule, was described.     

Synthesis, structures, and photophysical properties of silicon and carbon-bridged ladder oligo(p-phenylenevinylene)s and related π-electron systems

A series of partially or fully fused ladder oligo(p-phenylenevinylene)s (LOPVs) and related π-electron systems has been synthesized. Thus, the intramolecular reductive cyclization of o-silyl-substituted bis(phenylethynyl)benzenes with lithium naphthalenide produces partially silicon-bridged bis(styryl)benzenes consisting of silaindene or disilaindacene skeletons. By combining this cyclization with the Friedel-Crafts type electrophilic cyclization, a homologous series of the fully fused LOPVs and related compounds, bearing silicon and carbon bridges, has been synthesized in fairly good yields. The longest example of the LOPVs is the 13-ring-fused system that has a nearly flat π-conjugated framework with a length of 2.9 nm, as proven by X-ray crystallography. All the produced ladder π-electron systems show intense fluorescence in the visible region with high quantum yields as well as relatively small Stokes shifts. As the silicon contents increase or the disilaindacene skeleton is incorporated, the emission maxima shift to the longer wavelengths and the fluorescent quantum yields slightly decrease. These trends can be rationalized as due to the σ* effect of silicon, wherein the silicon bridges contribute to the electronic structure through σ*-π* orbital interaction that cause the red-shifts in the emission maxima and suppress the radiative decay process from the singlet excited state.