Photochemical Ionic-Conductivity Switching Systems of Photochromic Crown Ethers for Information Technology

Design of two types of ion-conducting systems using photochromic crown ethers as the photocontrol agents is described; one type is based on the phase transition of azobenzene derivatives induced by their photoisomerization and the other based on the molecular control of metal ion complexation by crowned spirobenzopyrans. The photoresponsive ion-conducting systems are applicable to electrostatic imaging and photorefractive materials.     

Efficient and widely applicable method of constructing neo-proteoglycan utilizing copper(I) catalyzed 1,3-dipolar cycloaddition

Efficient constructions of two types of neo-proteoglycan are described. Enzymatically prepared alkyne containing chondroitin 6-sulfate chains and chemically synthesized azido group having compounds are linked by utilizing the copper(I) catalyzed 1,3-dipolar cycloaddition.     

Product analyses and crosslink mechanism of plasma-polymerized methyl methacrylate

Plasma-polymerized methyl methacrylate (PPMMA) film was produced by a radio-frequency glow discharge of methyl methacrylate (MMA) gas with argon. PPMMA deposited under a plasma of mild energy was separated into a soluble fraction (sol-PPMMA) and an insoluble matrix (insol-PPMMA), which is highly crosslinked, by solvent-extraction and filtration. The chemical structure of the sol-PPMMA was determined by pyrolysis/gas chromatography, IR spectroscopy, ¹H-NMR, ¹³C-NMR, and elemental analysis techniques. On the other hand, the structure of the insol-PPMMA was examined with IR spectroscopy, ¹³C-NMR with CP/MAS method, and elemental analysis. The crosslinking mechanism in the plasma polymerization of MMA is discussed on the basis of product analyses of the sol-PPMMA and the insol-PPMMA.     

Kinetics of catalytic combustion in air over Pt/Al2O3/Al catalyst

Summary Catalytic combustion of toluene, propylene and CO over Pt/Al₂O₃ /Al catalyst was investigated. Strong inhibition effects are observed when the mixture of toluene, propylene and CO is oxidized. A reaction mechanism of catalytic combustion over Pt/Al₂O/Al is proposed. The results from kinetic models are in good agreement with the experimental data.     

The flameless atomic absorption spectrometric determination of aluminum with a carbon atomization system

The atomic absorption spectrometry of aluminum with a carbon tube atomizer is described, with particular reference to the heating cycle, argon flow rate and amplifier time constant. Interferences are eliminated by pre-atomization heating or with a hydrogen-argon-entrained air flame. Under optimal conditions, the sensitivity (1 % absorbance) is 5·10^?11g, and the relative standard deviation is 2.3 for 2.5 ng Al.     

Soluble polymer-supported catalysts containing pendant quaternary onium salts for the addition reaction of oxiranes with carbon dioxide

The addition reaction of oxiranes ( 15a-d ) with carbon dioxide (CO₂) was carried out using 1 mol % of soluble polymer-supported quaternary onium salts as catalysts under atmospheric pressure. The reaction of 15a-d with CO₂ proceeded very smoothly to give the corresponding five-membered cyclic carbonates ( 16a-d ) in high yields at 90-100°C. The catalytic activity of the soluble polymer-supported quaternary onium salts was strongly affected by the following factors: kind of reaction solvent, degree of introduction of the pendant onium salt residues in the polymer chain, and type of alkyl group on the onium salts due to the balance between lipophilicity and steric hindrance of the onium salt residue. Furthermore, these soluble polymer-supported quaternary onium salts were found ordinarily to have higher catalytic activity than low molecular weight quaternary onium salts under the same reaction conditions. It was also found that the rate of reaction was proportional both to catalyst concentration and to oxirane concentration. © 1995 John Wiley & Sons, Inc.     

Ionic-conductivity switching of vinyl malachite green leuconitrile copolymers based on photoinduced carrier generation

Copolymers of bis[4-(N,N-dimethylamino)phenyl]-4-vinylphenylmethanenitrile (vinyl Malachite Green leuconitrile) with methyl methacrylate or ω-methoxyoligo(oxyethylene) methacrylate have been synthesized, aiming at designing one-component-type organic polymers for photoswitchable ion-conducting films. The triphenylmethanenitrile copolymers with ω-methoxyoligo(oxyethylene) methacrylate were found to undergo ionic-conductivity switching by turning on and off UV light at ambient temperature, owing to their low glass transition temperature. © 1993 John Wiley & Sons, Inc.     

Determination of magnesium and calcium ions in seawater by capillary zone electrophoresis

Capillary zone electrophoresis is proposed for the determination of magnesium and calcium ions in seawater. A carrier solution containing EDTA was adopted for the complexation of these ions and the effect of sodium chloride concentration in the sample solutions on the results was examined. It was found that magnesium and calcium ions could be determined without any pretreatment by injecting 100-fold diluted seawater samples. Linear calibration graphs were obtained for standard solutions containing up to 10.0 mg/l of calcium ion when both peak area and peak height were used. On the other hand, a linear calibration graph was obtained for standard solutions containing up to 20.0 mg/l of magnesium ion when the peak area was used, while a curved one was obtained when the peak height was used. Relative standard deviations were 0.8 and 1.2% when a standard solution containing 5.0 mg/l of magnesium and 8.0 mg/l of calcium ions was analysed 8 times using the peak area. Limits of detection for magnesium and calcium ions were 0.13 and 0.26 mg/l, respectively. The proposed method was applied to the determination of magnesium and calcium ions in surface and bottom seawater samples.     

1-D cobalt(II) spin transition compound with strong interchain interaction: [Co(pyterpy)Cl(2)].X

Cobalt(II) compounds [Co(pyterpy)Cl(2)].MeOH (1.(MeOH)) and [Co(pyterpy)Cl(2)].2H(2)O (1.(2H(2)O)) were synthesized. The compound 1.(MeOH) forms the quasi 3-D networks by making pi-pi stacking between the 1-D chains. The methanol molecules from 1.(MeOH) can be removed by heating, and substituted by absorption of water molecules. The MeOH molecules in 1.(MeOH) are removed by heating at 410 K, and they are substituted by water molecules to form 1.(2H(2)O). 1.(2H(2)O) exhibits a S = (3)/(2) (HS) left arrow over right arrow S = (1)/(2) (LS) spin transition with a thermal hysteresis. We have succeeded in constructing a guest dependent 1-D spin-crossover cobalt(II) compound.     

Preferential CO oxidation promoted by the presence of H2 over K-Pt/Al2O3

In preferential CO oxidation in H2-rich gas, K-Pt/Al2O3(K/Pt = 10) was very effective in decreasing CO concentration below 10 ppm in the 375-410 K range, and the turnover frequency of the K-Pt/Al2O3 was 20 times as high as that of Pt/Al2O3 at 353 K; furthermore, the activity of CO oxidation was promoted drastically by the presence of H2.