Synthetic studies on macrolactin A by using a (diene)Fe(CO)3 complex

The stereoselective synthesis of the two segments 3 and 4 of macrolactin A 1 is described. Macrolactin A is a 24-membered polyene macrolide antibiotic, which is of interest due to a strong activity against B16-F10 murine tumor cell and HIV-1 virus. The key step of the synthesis is the 1,2-migration reaction of a (diene)Fe(CO)₃ complex with a introduction of the thiol group to construct the unstable (E,Z)-conjugated dienic moiety (C8-C11).     

Two novel dicoumaro-p-menthanes from Gerbera piloselloides (L.) CASS

Two new type dicoumarins (dicoumaro-p-menthanes), named dibothrioclinins I (1) and II (2) were isolated from the roots and rhizomes of Gerbera piloselloides (L.) CASS., collected in Yunnan Province, China. Their structures were elucidated on the basis of MS, 1D ((1)H-NMR, (13)C-NMR, DEPT and NOE) and 2D ((1)H-(1)H COSY, HMQC, HMBC) NMR spectral analyses. The relative structures of the two compounds were established by NOE difference spectroscopy and further confirmed by single-crystal X-ray diffraction studies.     

Rational design of CH/pi interaction sites in a basic resolving agent

A novel synthetic basic resolving agent, cis-1-aminobenz[f]indan-2-ol (ABI), was rationally designed by introducing effective CH/pi interaction sites to cis-1-aminoindan-2-ol (AI), whose chiral recognition ability has been reported from our laboratory. ABI was applicable to a wide variety of racemic arylalkanoic acids and showed moderate to excellent chiral recognition ability, which was obviously higher than that of AI. The fundamental and important role of CH/pi interactions, such as tunable CH(sp(2))/pi and CH(sp(3))/pi interactions, in the chiral recognition by ABI was revealed by X-ray crystallographic study.     

Novel neuronal nitric oxide synthase (nNOS) selective inhibitor, aplysinopsin-type indole alkaloid, from marine sponge Hyrtios erecta

Two novel aplysinopsin-type indole alkaloids, 1 and 2, and three known indole alkaloids were isolated from the marine sponge Hyrtios erecta. These compounds exhibited selective inhibitory activity against the neuronal isozyme of nitric oxide synthase (nNOS). Furthermore, new quinolone 7 was also isolated from the same marine sponge. The chemical structures of these new compounds were elucidated on the basis of spectroscopic analysis.     

Hydrogen Gas Sensing of High Electrical Conducting-P2O5-SiO2 Glasses Prepared by Sol-Gel Process

High proton-conducting P₂O₅-SiO₂ glass was applied to the electrolyte of the hydrogen concentration cell for hydrogen gas sensing. 5P₂O₅·95SiO₂ glass was prepared using the sol-gel method and its electrical conductivity and electromotive force were measured at 50°C as a function of both the ambient humidity and hydrogen gas concentration. The electrical conductivities increased with increasing humidity and reached 10^–2 S/cm at 90% relative humidity. The electromotive force of the hydrogen concentration cell, where the glass was used as a membrane, showed good Nernstian response to hydrogen pressure in the high relative humidity region.     

Amphidinolide X,a novel 16-membered macrodiolide from dinoflagellate Amphidinium sp

A novel cytotoxic 16-membered macrodiolide, amphidinolide X (1), has been isolated from a marine dinoflagellate Amphidinium sp. (strain Y-42). The gross structure of 1 was elucidated on the basis of spectroscopic data including one-bond and long-range (13)C-(13)C correlations. The relative and absolute stereochemistries were determined by combined analyses of NOESY data and (1)H-(1)H and (1)H-(13)C coupling constants of 1 and NMR data of the degradation products. Amphidinolide X (1) is the first macrodiolide consisting of polyketide-derived diacid and diol units from natural sources. The biosynthetic origins of 1 were investigated by means of feeding experiments with (13)C-labeled acetates.     

Some aspects of plasma copolymerization of acetylene with N2 and/or water

Plasma polymerizations of mixture of acetylene-N₂, acetylene-H₂O, were investigated by using an electrodeless glow discharge from a 13.5-MHz radiofrequency source. Properties of plasma polymers were examined as functions of mole ratios of N₂ and/or H₂O to acetylene. The concentration of trapped free radicals and the internal stress in a plasma polymer decreased as the mole ratio of N₂ or H₂O increased. Water showed the most pronounced effects in those properties at the mole ratio of 0.3. Gas permeabilities increased by the copolymerization of N₂ and/or H₂O. Surface energies were also investigated by analysis of contact angles of liquids. Copolymerization of N₂ caused a remarkable increase in polar contribution of surface energy. Some fundamental aspects of flow-rate pressure relationship of mixed gases are presented.     

The complexation of 2,3-anthracenedicarboxylate by β- and γ-cyclodextrins in mixed solvent systems as studied by induced circular dichroism. The role of cosolvent hydrophobicity

The complexation of 2,3-anthracenedicarboxylate (ADC) by- and-cyclodextrins in water containing an organic solvent has been studied by induced circular dichroism. It has been shown that an increase of organic solvent ratio causes the degradation of the 1:1 ADC:-CD complex and the liberation of one guest molecule from the 2:1 ADC:-CD complex in water. The higher the hydrophobicity of the cosolvent, the weaker the complexation of ADC by-CD.     

Preparation and properties of aromatic copolyamides from aromatic diisocyanates and aromatic dicarboxylic acids

Wholly aromatic random copolyamides of high molecular weights were prepared by the high-temperature solution polycondensation of an aromatic diisocyanate, 4,4′-methylenedi(phenyl isocyanate) or 2,4-tolylene diisocyanate, with a mixture of isophthalic acid and 4,4′-oxydibenzoic acid. Glass transition temperatures of the polyamides and copolyamides were between 229 and 273°C; this depended on the combination of diisocyanates and dicarboxylic acids used. These aromatic copolyamides showed better solubility in various organic solvents and reduced crystallinity, compared to the corresponding homopolyamides. The copolyamides prepared from 2,4-tolylene diisocyanate had greater solubility and higher glass transition temperatures than those obtained from 4,4′-methylenedi(phenyl isocyanate).     

Three bits eight states photochromic recording and nondestructive readout by using IR light

A photochromic polymer film containing three different diarylethene derivatives, that is, 1,2-bis(3,5-dimethyl-2-thienyl)perfluorocyclopentene (1), 1,2-bis(2,5-dimethyl-3-thienyl)perfluorocyclopentene (2), and 1,2-bis(2-methyl-5-phenyl-3-thienyl)perfluorocyclopentene (3) was prepared. Upon UV irradiation, the three derivatives changed to their closed-ring isomers having different colors, yellow, red, and blue. They showed different spectra not only in UV/Vis region but also in the IR spectral region. Upon irradiation with visible light of appropriate wavelengths, each closed-ring isomer was selectively bleached, and three bits eight states recording was performed. The eight states could be read out nondestructively by using IR light of appropriate wavenumbers.