Heteroatom-bridged calixarenes have been confined into the unexplored frontier of the vast realm of the calixarene chemistry because of their synthetic difficulty. The circumstances have been changed by our facile one-step synthesis of thiacalix[4]arene, in which four methylene bridges of calix[4]arene are replaced by four sulfides, by heating a mixture of p-t-butylphenol and elemental sulfur in the presence of a base. The availability of thiacalix[4]arene in substantial amounts allowed us to engage in a project for modifications and functional developments of this cyclic entity by taking advantage of unique properties of the bridging sulfide. For example, the ready oxidizability of the bridging sulfides provided sulfinylcalix[4]arenes and sulfonylcalix[4]arenes. By stereocontrolled oxidation, all four kinds of stereo isomers of sulfinylcalix[4]arenes, imposed by configurations of four SO groups, could be obtained. Oxidation of one or two adjacent sulfides to sulfoxides in O-alkylated thiacalix[4]arenes gave novel chiral molecules. Chelation-assisted nucleophilic aromatic substitution reaction was applied to sulfinyl- and sulfonylcalix[4]-arene to lead to aminocalix[4]arenes consisting of four aniline and four bridging groups S, SO, or SO₂. In terms of functions, thiacalix[4]arene is revealed to have higher inclusion ability toward halomethanes than calix[4]arene, which was applied to the removal method of them from aqueous solutions. Solvent extraction study showed that thiacalix[4]arene has high binding ability toward soft metal ions, owing to the coordination ability of the bridging sulfur. The metal ion selectivity was conveniently controlled by the oxidation state of the bridging moiety. Chiral stationary phases for gas-chromatographic separation of enantiomers were prepared by introducing chiral substituents into thiacalix[4]arene to show higher enantio-selectivity than methylene-bridged counterparts did. Thus, we have revealed versatility of thiacalixarenes, which is not attainable by conventional calixarenes.

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We analyzed UV absorption, circular dichroism, and ¹H-NMR spectra of the 1 : 1 inclusion complexes formed between β-cyclodextrin (β-CDx) and racemic 1-(1-phenylethoxy)-2-pyridone and its methyl derivatives. The phenyl moiety in the guests turned out to be preferentially immersed into the β-CDx cavity leaving the pyridone chromophore around the rim of the secondary hydroxy group side. In addition, it was shown that the methyl substituent introduced at the 6 position of the pyridone ring exerts its effect so as to increase the stability of β-CDx inclusion complex formed. However, the β-CDx cavity exhibited a poor chiral recognition ability for racemic 1-(1-phenylethoxy)-2-pyridone, while its ability underwent methyl substituent effects to only a very small extent.

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Various radical initiators were used for investigating the hydrogen abstraction reaction on hydrogenated diamond surface. Benzophenone excited by UV light, which is one of the most popular photosensitizers, could not abstract the hydrogen atoms. Thermally excited α,α′-azobisisobutyronitrile (AIBN), which is one of the most popular radical initiators of azo compounds, could also not abstract the hydrogen atoms. On the other hand, benzoyl peroxide, which is one of the most popular radical initiators of peroxide compounds, could abstract the hydrogen atoms. The reaction rate of the hydrogen abstraction reaction by benzoyl peroxide depended on the species of solvent. The hydrogen atoms in CH₂ group on (100) face are more reactive than that in CH₃group on (111) face.

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The activated carbon, produced from sugarcane bagasse in China, has been used for decolorization of synthetic melanoidin. The melanoidin is the pigment in molasses. It is synthesized from glucose, glycine and sodium hydrogencarbonate. The bagasse, as the raw material of activated carbon, was generated from sugar manufactory’s waste. Therefore it is cheap and easy to obtain. This activated carbon has been produced by steam activation of sugarcane bagasse at the temperature of 1073 K. The produced activated carbon has the similar specific area as the commercial coconut activated carbon (878 × 10³ m²/kg). The activated carbon of bagasse in China has the same or more adsorptive capacity of melanoidin as compared with that of activated carbon of bagasse in Thailand and Brazil. Also, as the regeneration cycle increased, the capacity of the micropore decreased and the capacity of mesopore increased. Consequently, the structure of the pore changed. The experiment equation was deduced from the correlation between the regeneration cycle and regeneration yield of activated carbon of bagasse in China.

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We have studied the characteristics of glycerol type nonionic surfactant (3,3′-oxybis (1,2-propanediol) 1-dodecyl ether; R₁₂G₂E) by phase diagram. Comparing with oxyethylene type nonionic surfactant (α-dodecyl-ω-hydroxyhexa (oxyethylene); R₁₂EO₆), we have found three unique characters. First, from very low concentration of R₁₂G₂E, it could solubilize water and oil. This means these kind of surfactants have a strong lipophobicity as well as a strong hydrophobicity. Second, the amount of R₁₂G₂E to solubilize whole water and oil was very small. And third, R₁₂G₂E was less affected by the temperature change, comparing with R₁₂EO₆.
Because of these characters of R₁₂G₂E, its phase diagram on the plane of water/oil = 1/1(wt), in water/surfactant/oil system, showed “Humpback-whale” figure, while that of oxyethylene type nonionic surfactant in the same condition showed ordinary “Fish-like” figure.

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Aqueous two-phase system formed by mixing (NH₄)₂SO₄ and tetrabutylammonium bromide (TBAB) has been applied to the gentle separation of trisodium salt of copper (II) chlorophyllin (CuCL–Na). An aqueous two-phase system was obtained as follows: to a 3.0 mL of 1.0 mol/L TBAB aqueous solution, 1.0 mL of CuCL–Na aqueous solution containing less than 0.30 mg of CuCL–Na, 1.0 mL of pH 8 buffer solution and 1.1 g of (NH₄)₂SO₄ were added and the mixture was shaken for 1 min, then left at room temperature for 3 h. A 0.5 mL portion of the top phase was diluted to 10 mL with water and its absorbance was then measured at 405 nm against a reagent blank similarly prepared.
The CuCL–Na can be quantitatively extracted into the TBAB-rich upper phase at the wide pH range. It was considered that the extractable species was an ion pair complex of the type CuCL–TBA.

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Degradation of coals and chars from poly(vinyl chloride) (PVC) and mixtures of PVC with other polymers such as polyethylene glycol, poly(vinyl alcohol), polystyrene, and polyethylene using a mixture of copper(II) oxide (CuO) and aqueous potassium carbonate solution at 500 °C to give a mixture of aliphatic and aromatic hydrocarbons, carbon dioxide, potassium hydrogencarbonate, and water soluble and easily decomposable materials with dilute hydrochloric acid. It was revealed that CuO promoted the decomposition of highly aromatized materials such as chars from PVC or coals and the preferential formation of benzene in the decomposition of those materials.

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