One of the ultimate research goals of materials science would be the construction of molecular machines, where one molecule mechanically works as a machine by external energy sources. Recently we have first succeeded in the construction of a light-powered chiral molecular motor, which photochemically rotates only in one-direction reflecting the chirality of the motor molecule. The motor rotation is also controlled by the “ratchet effect” due to the irreversible isomerization. In this paper, we account for the unique chemistry of motor molecules, chiral and helical olefins of 1, 1′, 2, 2′, 3, 3′, 4, 4′-octahydro-3, 3′-dimethyl-4, 4′-biphenanthrylidene(E)-(3) and(Z)-isomer(4), and also report the irreversible thermal isomerization of unstable(3R, 3′R)-(M, M)-(E)-3 to stable(3R, 3′R)-(P, P)-(E)-(−)-3, which works as the “ratchet effect” of the motor. The stereochemistry and rotation mechanism of the motor are explained.

View full abstract

A nano-composit organic polymer with clay minerals, which was developed by Toyota Central R & D Labs, Toyota Motor Co. and Ube Industry Ltd., is reviewed. A cation exchange of montmorillonite for amino-acid cations and polymerization of ε-caprolactam in interlayer regions produced a novel nano-composite; NCH(Nylon Clay Hybrid), materials, in which silicate layers of the clay minerals with about 1nm in thickness are dispersed in the nylon 6 matrix. The NCH shows not only excellent mechanical and heat resistant properties but also a good gas barrier effect, which is essential for envelop films. The properties made it possible to industrial uses of the NCH as parts for automobile and wrapping films for foods. The success of the NCH has awoke us importance of a nano-meter scale structure control, and an organic/inorganic interaction for the preparation of materials. This work has initiated following many researches and developments concerning nano-composits, hybrids, mesoporous materials and bio-mineralization.

View full abstract

The reforming reactions of CH₄ with CO₂ diluted with He were carried out over the cobalt catalysts prepared from the perovskite structural oxides, LnCoO₃(Ln=La, Pr, Nd, Sm, Eu, Gd, Er, Tb) and the relationship between the reaction activity and the surface properties of the catalysts were examined. The reaction activity at 873K of the catalysts containing the rear earth element of higher atomic number than Eu was remarkably higher than that of the catalysts having lower atomic number than Eu.
The surface properties of the Co/La₂O₃, Co/Sm₂O₃ and Co/Eu₂O₃ catalysts decomposed from LaCoO₃, SmCoO₃ and EuCoO₃ were particularly examined. EuCoO₃ was reduced much easier to metallic cobalt and europium oxide than LaCoO₃ and SmCoO₃. The decomposed products by reduction were led to the catalyst with high activity. On the other hand, LaCoO₃ and SmCoO₃ were not fully and easily reduced and very small amount of cobalt oxides remained on the surface. The difficulty of reducibility of LaCoO₃ and SmCoO₃ caused the lost or low activity. The decomposed Co/Eu₂O₃ catalyst had two kinds of active sites which operated at relatively low(873K) and high temperature(1073K) regions. The other two kinds of catalysts had only one active site which operated at high temperature. This caused the lost or low activity at low temerature such as 873K in the case of the latter. Especially the decomposed Co/La₂O₃ catalyst had a strong affinity to CO₂ and easily produced a lanthanum carbonate which was decomposed at high temperature(>973K). The formation of the carbonate inhibited the reaction, probably by the oxidation of the metallic cobalt on the catalyst surface.

View full abstract

Nickel(II) sulfate supported on γ-Al₂O₃(NiSO₄/Al₂O₃) was prepared and its catalytic activity for low temperature selective reduction of NO_x with ammonia was examined.
The catalyst(NiSO₄/Al₂O₃) was effective for the catalytic reduction of NO_x at high concentration of NH₃ and of SO₂. Thus, it exhibited about 80% NO_x conversion under the following conditions: NO:250ppm, NH₃:1000ppm, SO₂:800ppm, O₂:4%, CO₂:14%, and N₂ balance and GHSV 750h^-1 at 90°C. It is inferred that the high NO_x reduction activity of NiSO₄ catalyst resulted from the presence of the Brönsted acidity and oxidation ability of ammonia. The catalytic activity of NiSO₄ was stable for 100h, but gradually decreased by further reaction. The characterization by XRD revealed that the reason of catalytic deactivation was accumulation of ammonium sulfates and ammonium nitrate plugged the pores of the catalyst. The activity of deactivated catalyst was easily regenerated by water washing treatment.

View full abstract

Spectroscopic behavior of the coumarinyl-substituted sulfonium-salt pendants attached to the methionine-192 residue of α-chymotrypsin was compared with that of the corresponding reference sulfonium salts.It was suggested that a spatial arrangement of the coumarin ring and a water molecule immobilized in this enzyme binding site play critical roles in determining the acidity of the pendants in the ground and excited singlet states, respectively.

View full abstract

In recent years, organic nonlinear optical materials have become of considerable interest for potential applications in optoelectronics. An organic salt 4-(4-dimethylaminostyryl)-1-methylpyridinium tosylate(DAST) crystal has extremely large optical nonlinearities and is a promising material for optical switching and frequency conversion. DAST crystal grown in b direction with sufficient length is necessary to utilize the largest electro-optic coefficient r₁₁ and the crystal should take waveguide structure in order to fabricate highly efficient optical devices.
In methanol solution, growth rate of[100] direction of DAST crystal is faster than that of[-100] direction and growth rate of[001] direction is faster than that of[00-1] direction. In this paper, crystal growth from a seed crystal was performed by temperature lowering method and the crystal with ridge structure parallel to b axis was grown successfully by using a substrate with a grooved structure and applying the growth behavior of the crystal.

View full abstract

A new activated carbon production process from scrap tire using a fluidizing bed was proposed. The apparatus used for the laboratory test was as follows; a reaction tube made of quartz was 30mmφ×300mm long and was set in a vertical electric furnace. On the distribution plate placed at the center of the reaction tube, a raw material mixture of 5g of rubber tip with 2-4mmφ and 10g of sand with<1mmφ was fed. The furnace was heated at 10°C/min under N₂ stream of 200mL/min. Water of 1.2mL/min was introduced to the stream at 600°C. Activated carbon was produced at the reaction temperatures of 800-850°C during reaction period in the range of 30-120min. Medium sand mixing promoted the activation, and activated carbon with the BET surface area of 708m²/g was obtaind. Additionally, from a TG test and a gas chromatogram it was found that thermal decomposition of tire is completed below 500°C. The residual carbon was processed as the raw material for next activation process. A new activated carbon production process using a fluidizing bed was presented. This medium sand fluidizing bed consists of two stages: upper stage; decomposition, and lower stage; activation.

View full abstract

Three strains(Haliclona permolis, Halichlona sp. white and Halichondria japonica)of sponge collected from Akinada in Seto Inland Sea were tested for their ability to collect metal ions. A 50mL solution containing Cd, Co, Cu and Ni was mixed with 100mg of the sponge under stirring for 30min. The concentrations of metal ions in the solution were determined with an atomic absorption spectrometer. Haliclona permolis tested was found to collect larger amounts of Cd, Cu, Ni and Co than Halichlona sp. white. The adsorption order of metals by sponge(boiling water-treated) was Cd>Cu, Ni>Co.

View full abstract

Solid solutions of La₂(SO₄)₃ and Al₂(SO₄)₃ were prepared by rapidly drying mixed aqueous solutions using micro-wave heating. The La³⁺ion is soluble into the anhydrous aluminum sulfate crystal lattice up to about 6mol%. On heating the thermal decomposition starts at 830°C for the pure Al₂(SO₄)₃, while at 760°C for 6mol% La₂(SO₄)₃ contained Al₂(SO₄)₃. The anhydrous aluminum sulfate solid solution thermally decomposes into the η-Al₂O₃ without any other crystalline phases. The LaAl₁₁O₁₈ is formed after heating the desulfurized product at 1300°C without forming LaAlO₃ when the content of La₂O₃ is less than 6mol%.The La³⁺ doping increases the stability of η-Al₂O₃ at high temperatures. The phase transformation of alumina takes place above 1350°C when the amount of La₂O₃ is 5mol%.

View full abstract

Algae in water was separated by using superconducting high gradient magnet after magnetization of algae by means of attaching the colloidal particles of hydrous iron(III) oxide. It is found that the percentage of recovery of algae depends on the added amount of oxide particles. The percentage of recovery was also found to reach almost 100% when the very small amount of particles was added to the algae suspension.These results demonstrate the feasibility of the magnetic separation of algae with no addition of polymer surfactant.

View full abstract