Gaseous adsorption properties of a silica-pillared layered manganese oxide

Adsorptions of N(2), H(2)O, and organic vapors including CH(2)Cl(2), CCl(4), c-C(6)H(12), C(6)H(6), n-C(6)H(14), and n-C(9)H(20) on a silica-pillared layered manganese oxide (SiHMnO) and nonane-preadsorbed SiHMnO were examined. It is found that SiHMnO has a microporosity with a wide pore width distribution showing different pore wall affinities. Micropores with smaller width preferentially accommodate the nonane preadsorbate while the surface hydrophilicity of pore wall leads to an easier detachment of the adsorbed nonane molecules. H(2)O adsorption influences both the porosity and the surface properties by accelerating a sufficient hydrolysis of the remained TEOS molecules in SiHMnO. Examinations using Dubinin-Radeshkevich (DR) equation and isosteric heat of adsorption of organic molecules provide evidences that the wall surface of micropores with smaller and larger width have less affinity toward nonpolar and polar organic vapors, respectively.     

5-Fluorouracil derivatives with serum protein binding potencies

To develop an optimal delivery system for 5-fluorouracil (5FU) using serum protein as a drug carrier, a series of its benzyl derivatives was synthesized. Then their binding to the serum protein was investigated by equilibrium dialysis. The benzyl derivatives of 5FU were strongly bound to rat plasma protein or human serum albumin. The bound percentage increased with increasing hydrophobicity. It was suggested that the benzyl derivative of 5FU existed in the blood as a complex with serum albumin and circulated for a long time as a polymeric drug does.     

The first total synthesis of (+/-)-linderol A, a tricyclic hexahydrodibenzofuran constituent of Lindera umbellata bark, with potent inhibitory activity on melanin biosynthesis of cultured B-16 melanoma cells

[reaction in text] The first total synthesis of (+/-)-linderol A, a hexahydrodibenzofuran isolated from Lindera umbellata bark, with potent inhibitory activity on melanin biosynthesis of cultured B-16 melanoma cells was achieved via a 20-step of reaction in 7.64% overall yield starting from 4,6-dimethoxysalicylaldehyde.     

Application of an Ion Beam Technique for the Design of Visible Light-Sensitive, Highly Efficient and Highly Selective Photocatalysts: Ion-Implantation and Ionized Cluster Beam Methods

As a new concept for the design of effective photocatalysts, an ion beam technology using accelerated metal ions, a metal ion implantation and an ionized cluster beam (ICB) method, have been applied to design unique photocatalysts. The metal ion implantation of TiO₂ and Ti-containing zeolites with highly accelerated metal ions (V⁺, Cr⁺, etc.) is useful in designing photocatalysts that can operate efficiently under visible light irradiation. Also, an ICB method with a low acceleration energy is useful in preparing transparent TiO₂ thin films on various types of substrates for the efficient photocatalytic degradation of pollutants diluted in water and air. The combination of the ICB method and metal ion implantation can develop the TiO₂ thin films that are able to operate not only under UV light but also under visible light irradiation.     

Preparation and separation of all possible rotamers of a stereochemical analog of meso-tartaric acid: optically inactive and optically active isomers of (R,S)-2,2′-bis(methoxycarbonyl)-6,6′-dimethyl-9,9′-bitriptycyl

All the three possible rotamers of the title compound were separated by chromatography, and unambiguously identified by NMR and X-ray analysis. One of the isomers was optically inactive C_i conformation. The other optical active forms were resolved to give a pair of enantiomers, which were characterized by optical rotation and CD spectra. Thus the optical inactivity of a compound such as meso-tartaric acid that can take C_i conformation in solution, is now ascribed to that the molecule has an optically inactive C_i conformer and equal amounts of optically active conformers, that are enantiomers, in solution.     

Novel Knöevenagel-type reaction via titanium enolate derived from Ti(O-i-Pr)4 and diketene

Knöevenagel-type reaction between diketene and aldehydes proceeded in the presence of Ti(O-i-Pr)₄. This reaction proceeded via titanium enolate derived from Ti(O-i-Pr)₄ and diketene. As for the stereoselectivity of the products, E-isomers were produced predominantly in the case of aromatic aldehydes.     

Heterometallic hexanuclear cluster with an S = 8 spin ground state: MnII[MnII(hfac)2]3[NiII(pao)3]2 (hfac- = hexafluoroacetylacetonate,pao- = pyridine-2-aldoximate)

The heterometallic Mn(II)(4)Ni(II)(2) title compound has been synthesized and characterized by X-ray crystallography. The compound consists of a Ni-Mn-Ni linear moiety, [[Ni-(mu-NO)(3)](2)-Mn], linked by oximate bridges and three Mn(II) hfac terminal units attached by oximate oxygens in a di-mu-oxo fashion, forming a novel heterometallic cluster: Mn[Mn(hfac)(2)](3)[Ni(pao)(3)](2) (1). Magnetic measurements reveal the antiferromagnetic nature of the oximate pathway between Mn(II) and Ni(II) metal ions, which imposes an unusual high-spin ground state (S = 8) for 1.     

Synthesis, characterization and FET properties of novel dithiazolylbenzothiadiazole derivatives

Dithiazolylbenzothiadiazoles easily obtained have high electron affinity and the FET device of a trifluoromethylphenyl derivative exhibited a good n-type performance with high electron mobility.     

Cationic polymerization of vinyl monomers initiated by phosphorus compounds containing halogens

Polymerization of vinyl monomers having large negative e values in the presence of phosphorus compounds containing halogens was studied in order to examine the cationic initiation ability of phosphorus compounds. N-Vinylcarbazole was effectively polymerized by phosphorus compounds such as PCI₃, PBr₃, PCI₂C₆H₅, PCI(C₆H₅)₂, POCI₃, and POCI₂C₆H₅ even in benzene. The initiation ability of phosphorus compounds decreased in the order; PCI₂ ? PBr₃ > PCI₂C₆H₅ > PCI(C₆H₅)₂, and also POCI₃ > POCI₂₆₅. On the other hand, PCI₃ and PBr₃, which were less effective than POCI₃, showed initiation ability for the polymerizations of styrene and α-methylstyrene in nitrobenzene as a solvent. The results of the copolymerization of styrene with methyl methacrylate by PCI₃ in nitrobenzene, the result of solvent dielectric constant effect, and the effect of additives such as water, tert-butyl chloride, triethylamine, and hydroquinone, indicate the polymerization of styrene by PCI₃ to proceed by a cationic mechanism.     

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.