Bulletin of the Chemical Society of Japan

Ikeda, Osamu; Kojima, Toyosei; Tamura, Hideo

doi: 10.1246/bcsj.59.3335pmid: N/A

Electrocatalysis of the heat-treated (5,10,15,20-tetraphenylporphyrinato)manganese(III) halides (MnIII(TPP)X, X:F−, Cl−, Br−, I−) for the O2 reduction in an alkaline solution has been studied by rotating ring-disc electrode technique, and the result was correlated with properties of the heat-treated MnIII(TPP)X, such as magnetic moment and electrical resistivity. The axial ligand X showed noticeable effect on the catalytic activity. The catalytic activity estimated from the overpotential changed in the following order: F−>Cl−>Br−>I−. The catalytic activity for reducing oxygen to OH− was low, but the same order of activity as the above applies. The order was interpreted by the σ-donating ability of halide ion X to dz2 orbital. The active site of the MnIII(TPP)X heat-treated at 700 °C for O2 reduction is ascribed to the metal ion, coordinated to slightly degraded or perfect N4 center, but not degradation products of the relevant compounds.

Kataoka, Yosuke

doi: 10.1246/bcsj.59.3341pmid: N/A

Constant-temperature constant-pressure molecular dynamics simulations of a two-dimensional aqueous solution-like system are performed at many temperatures under a constant pressure. The total number of molecules in the system is 576, and the mole fraction of the solute is 0.5. The mutual diffusion coefficient, the kinetic diffusion coefficient, and the velocity correlation between different molecules are thus obtained. The reduced kinetic diffusion coefficient has a maximum at an intermediate temperature under a constant pressure. This feature is consistent with the temperature dependence of the mean-square-concentration fluctuations. The lifetime of the local structure is estimated from the cross-correlation function of displacement, which is computed from the time-averaged configurations, where the average period is several times longer than the velocity-autocorrelation time. The correlation length of the local concentration fluctuations is obtained and compared with the snapshots of the configurations at several temperatures. The dynamical properties are qualitatively in agreement with those of an alcohol–water mixture.

Ichinose, Masao; Yasuoka, Takashi; Mitsuzawa, Shunmei; Sasaki, Tsunetaka

doi: 10.1246/bcsj.59.3347pmid: N/A

An electrolytic removal of potassium and sodium sulfates from aqueous solutions was worked out by using an active-charcoal cathode and a platinum anode with a porous porcelain septum between them. Maximum removal of nearly 99% was attained for these salts. The mechanism of removal was confirmed to be based on the facts that potassium and sodium ions are entrapped and concentrated as hydroxides in the pores of the active-charcoal cathode while sulfate ions are removed from the solution and concentrated as sulfuric acid in the anode chamber.

Okuyama, Kenji; Watanabe, Hitoshi; Shimomura, Masatsugu; Hirabayashi, Kiyoshi; Kunitake, Toyoki; Kajiyama, Tisato; Yasuoka, Noritake

doi: 10.1246/bcsj.59.3351pmid: N/A

Azobenzene-linked, single-chain ammonium amphiphile (C12AzoC5N+Br−), C33H54N3O3Br, was crystallized from their solutions in water and ethanol. The crystals are triclinic with the space group P\bar1, Z=2, a=3.4243(6), b=0.8525(1), c=0.6073(1)nm, α=73.45(1), β=88.03(1), and γ=93.32(1)°. The structure was solved by the direct method and refined anisotropically by the block-diagonal least-squares procedure: R=0.06 for 2917 observed reflections (2θ<105°, Cu Kα, λ=0.154184 nm). The crystal structure consists of regularly stacking bimolecular layers in which C12AzoC5N+Br− molecules incline about 30° to the layer surface. As expected from spectroscopic analyses, the azobenzene chromophore shows a head-to-tail (J-like) aggregation between adjacent molecules. The pronounced planarity of the azobenzene chromophore found in this crystal structure enables parallel stacking of phenyl groups in the J-like aggregation.

Maruyama, Kazunori; Tanizaki, Yoshié

doi: 10.1246/bcsj.59.3357pmid: N/A

Dichroic spectra of polyenes –(CH=CH)n– produced in heat-treated poly(vinyl alcohol) [PVA] film were determined for two cases; stretch (at 85 °C) after heat (120 °C), (Δ,S), and heat after stretch, (S,Δ). The dichroic ratios Rdn of component polyenes (n=2–6) were estimated by means of simulation. In both cases (Δ,S) and (S,Δ), the relation of Rdn vs. Rs (stretch ratio) kept the theoretical equation of the dichroism analysis. The relative angles among the transition moments μn (n=2–6) were in accordance with those obtained by drawings of trans-polyenes. The idea of an azimuth vector in the stretched PVA substrate was justified. The relation of Rdn(Δ,S)>Rdn(S,Δ) was always observed at any Rs. This was explained by the thermal orientation-relaxation of polymer chains.

Esumi, Kunio; Miyata, Kazuaki; Waki, Fumio; Meguro, Kenjiro

doi: 10.1246/bcsj.59.3363pmid: N/A

Adsorption of tetrachloro-p-benzoquinone(chloranil) from basic and acidic solvents on metal oxides, such as alumina and titania was carried out to understand the acid-base interaction at the interface. The amount of chloranil adsorbed decreases with an increase of acid-base interaction between the basic solvent and chloranil and also decreases with an increase of acid-base interaction between the acidic solvent and electron donor sites of the metal oxides for both metal oxides. Furthermore, the change in concentration of chloranil radicals formed on their metal oxides by the adsorption is correlated with the acid-base interaction at the interfaces.

Shimizu, Jun; Imamura, Kengo; Nogami, Takashi; Mikawa, Hiroshi

doi: 10.1246/bcsj.59.3367pmid: N/A

Phase transitions of unsymmetric bis(quaternary alkyl bromide) salts of 1,4-diazabicyclo[2.2.2]octane (DABCO)(C10–DABCO–Cn–Br2, 11≤n≤22) were studied on the basis of measurements of differential scanning calorimetries, infrared absorption spectroscopy, and bromide-anion conductivities. The DSC measurements showed two transition temperatures (Tc1 and Tc2, Tc1>Tc2); this exhibits the existence of the metastable phase for the DABCO salts (C10–DABCO–Cn-Br2, 12≤n≤22). The metastable phase was converted to the stable phase within several days except for C10–DABCO–Cn–Br2 (n=12, 22). The temperature dependence of the infrared absorption spectra revealed that the band progressions due to two different alkyl chains disappeared at Tc1 and appeared again at Tc2. This shows that the trans-zigzag conformation of the alkyl chains in the low temperature phase is destroyed by the conformational change above Tc1 and then recovered again below Tc2. Abrupt increases in the bromide-anion conductivities by 100–1380 times were observed at around Tc2 for the samples annealed beforehand above Tc1. However, the virgin samples showed much broader increases in the conductivities below Tc1; no conductivity jump was observed. The conductivity increase was caused by the conformational change in the alkyl groups. The concomitant formations of the voids facilitate the bromide-anion transport.

Srivastava, A K; Kojima, Isao; Miyazaki, Eizo

doi: 10.1246/bcsj.59.3375pmid: N/A

Complete neglect of differential overlap (CNDO) molecular orbital calculations using the method of Anno and Sakai for the evaluation of the valence orbital ionization potential (VOIP) were performed with the aim of studying the oxidation of carbon monoxide on nickel clusters. A cluster surface was assumed to be preadsorbed with oxygen and the variation of various bond energies with the approach of a carbon monoxide molecule was studied for different models. Various possibilities for the reaction path are discussed in the light of the theoretical findings and it is suggested that at a low coverage of oxygen the reaction may follow a Langmuir–Hinshelwood path, whereas at a high coverage, an Eley–Rideal path might be more probable.

Saitô, Hazime; Tabeta, Ryoko; Kuzuhara, Akio; Asakura, Tetsuo

doi: 10.1246/bcsj.59.3383pmid: N/A

An attempt was made to prepare [Ser-3,3-2H2]- and [Ala-3,3,3-2H3]-fibroins by feeding respective amino acids Dl-[3,3-2H2]-serine (Ser) and [3,3,3-2H3]-alanine (Ala), respectively, to silkworms, Bombyx mori and Philosamia cynthia ricini together with daily artificial diet. We recorded 2H powder-pattern NMR spectra of [Ser-3,3-2H2]- and [Ala-3,3,3-2H3]-cocoons and fibroins (10–20% deuteration) by means of the quadrupole echo method. It was found that separation of the 2H quadrupole splittings is 125 and 39 kHz, respectively, for [Ser-3,3-2H2]- and [Ala-3,3,3-2H3]-cocoons and fibroins, respectively. Accordingly, it was concluded that side-cain reorientation of Ser residue is virtually frozen irrespective of differences in conformations of silk I and silk II, suggesting that the hydroxyl groups in these cases might be hydrogen-bonded to C=O or NH groups in intra or interchain. On the other hand, side-chain methyl group of Ala residue in [Ala-3,3,3-2H3]-fibroin turned out to undergo rapid three-fold rotation about the Cα–Cβ axis, as viewed from data of the quadrupole splittings.

Tanaka, Fujio; Kawasaki, Yoshiko; Yamashita, Shigeru

doi: 10.1246/bcsj.59.3389pmid: N/A

The luminescence lifetime for Eu2(SO4)3 and EuCl3 in H2O and D2O has been measured at 0.01 and 0.001 mol dm−3 of Eu3+ and at various temperatures from 5 to 45 °C. The average number of water molecules coordinated to Eu3+ ion, q, is evaluated from the difference of the luminescence decay constants in the H2O and D2O solutions. By using the q value of 8.3 for aquaeuropium(III) ion in EuCl3 solutions, q values for Eu2(SO4)3 solutions were determined as a function of concentration and temperature. The average number of water molecules released from the primary hydration sphere by the inner-sphere complexation between Eu3+ and SO42− ions is given as Δq=8.3–q, and Δq value increases with concentration and temperature. From the values of Δq and the known equilibrium constants on the overall complexation, it is revealed that for both the unis(sulfato) and bis(sulfato) complexation the ratio of inner-sphere complex to outer-sphere complex increases with temperature and that about one water molecule is released from the inner hydration sphere surrounding Eu3+ ion on the formation of an inner-sphere unis(sulfato) complex. The coordination state of the unis(sulfato) complex and the thermodynamic quantities for the equilibrium between outer- and inner-sphere complexes are discussed.