High-Pressure Synthesis and Crystal Structure of B2S3

Two new high-pressure phases of binary boron-sulfur compounds, B₂S₃-II and B₂S₃-III, were synthesized at 3-6.2 GPa. A single crystal of B₂S₃-III was grown and the structure was determined (tetragonal, space group I4₁/a, a=16.086(2) Å, c=30.488(4) Å; V=7888(1) ų, Z=100, R=3.0% and R_w=2.8% for 3047 observed data [I>3.00σ(I)]. The structure of B₂S₃-III consists of two kinds of macrotetrahedra built up from 20 and 34 BS₄-tetrahedra. These macrotetrahedra connect each other to form an interpenetrating zincblende-type structure by sharing BS₄-tetrahedra at the corners of those. B₂S₃-III is anticipated having a rather disordered structure. From the UV-Vis diffuse reflectance spectrum, the optical band gap of B₂S₃-III was estimated to be 3.7 eV.     

Synthesis of acryloyl-type polymer fixing 5-fluorouracil residues through D-glucofuranoses and its antitumor activity

Acryloyl-type polymer fixing 1-β-carbonylethyl-5-fluorouracil residues through D -glucofuranoses via ester bonds was synthesized by means of polymerization of the corresponding monomer and polymer reaction. In order to provide the water-soluble objective polymer, the copolymerization of the acryloyl-type monomer with acrylamide was carried out. The extent of release of 5-FU residues from the copolymer was investigated in the enzyme or nonenzyme system in vitro. Furthermore, the antitumor activities of the water-insoluble homopolymer and water-soluble copolymer obtained were tested in vivo.     

FLAVIN-PHOTOSENSITIZED MONOMERIZATION OF DIMETHYLTHYMINE CYCLOBUTANE DIMER IN THE PRESENCE OF MAGNESIUM PERCHLORATE

We have investigated the photosensitized monomerization of the cis,syn -cyclobutane dimer of 1,3-di-methylthymine using riboflavin tetraacetate and a 5-deazaflavin derivative as photosensitizer. Although little monomerization of the dimer is induced by photoexcitation of the flavins in the absence of any additives, the flavins can function as an efficient photosensitizer in the presence of magnesium perchlorate. Mechanistic studies involving spectroscopic, quantum-yield and flash-photolysis measurements demonstrated that the photosensitized monomerization exclusively proceeds through electron transfer from the dimer to the triplet flavins complexed with Mg²⁺. The effects of magnesium perchlorate are compared with those on the chloranil-photosensitized monomerization and also with the effects of HClO₄ on the flavin-photosensitized reaction.     

Novel polycationic biocides: Synthesis and antibacterial activity of polymeric phosphonium salts

Various polymeric phosphonium salts and the corresponding low-molecular-weight model compounds were prepared and their antibacterial activities against Staphylococcus aureus and Escherichia coli were explored by the viable cell counting method in sterile distilled water. Antibacterial activity of the polymers was found to be higher than that of the corresponding model compounds, particularly against S. aureus. Furthermore, the polymeric phosphonium salt exhibited a higher activity by 2 orders of magnitude than the polymeric quaternary ammonium salt with the same structure except the cationic part. Compounds with the longest alkyl chain (octyl) studied were found to exhibit particularly high activity, and this finding may be ascribed to the contribution of the increased hydrophobicity of the compounds to the cidal activity. © 1993 John Wiley & Sons, Inc.     

New formation of a 1,3-dipole in the reaction of adamantanone azine with triazolinediones: In connection with reactivity toward singlet oxygen

Tricyclo[3.3.1.1]decanone azine ( adamantanone azine ) reacts with 4-substituted 1,2,4-triazoline-3,5-diones under elimination of diazo adamantane to give a 1,3-dipole ( “azomethinimine” ), which on treatment with dipolahophiles affords the [ 2 + 3] -cycloadducts. The reaction is compared with singlet oxygen oxidation.     

Cyclopalladation of the indole ring in palladium(II) complexes of 2N1O-donor ligands and its dependence on the O-donor properties

Synthetic, structural, spectroscopic, and kinetic studies have been carried out on the Pd(II) complexes of new 2N1O-donor ligands containing a pendent indole, 3-(N-2-pyridylmethyl-N-2-hydroxy-5-methoxybenzylamino)ethylindole (HMeO-iepp), 3-(N-2-pyridylmethyl-N-2-hydroxy-5-nitrobenzylamino)ethylindole (HNO2-iepp), and (N-2-pyridylmethyl-3-indolylethylamino)acetic acid (Hiepc) (H denotes a dissociable proton). [Pd(MeO-iepp)Cl] (2), [Pd(NO2-iepp)Cl] (3), and [Pd(iepc)Cl] (4) were prepared and revealed by X-ray analysis to have a pyridine nitrogen, an amine nitrogen, a phenolate or carboxylate oxygen, and a chloride ion in the coordination plane. UV absorption and 1H NMR spectral changes indicated that all the complexes could be converted to the indole-binding complexes where the O donor was replaced by the indole C2 atom by cyclopalladation in DMSO or DMF in the temperature range of 40-60 degrees C. Formation of the indole-binding complex species obeyed the first-order kinetics, from which the activation parameters were estimated. The formation rate was dependent on the properties of the O-donor group, a lower pKa value of its conjugate acid causing faster conversion to the indole-binding species in the order 2 (methoxyphenolate) < 3 (nitrophenolate) < 4 (carboxylate). On the other hand, the ratio of the indole-binding complex to the O-donor complex as a result of the conversion was greater for the complexes with a higher pKa value of the ligand OH group, the order being 2 > 3 > 4.     

Molecular Recognition of Nucleic Acid Bases in Water by Hydrogen Bonding of Poly(vinyldiaminotriazine)

Poly(2-vinyl-4,6-diamino-1,3,5-triazine) efficiently binds nucleic acid bases and nucleosides in water by using complementary hydrogen bonding. The binding activity decreases in the order: U, T > A C, G. The corresponding monomer shows virtually no activity, indicating a predominant role of polymer effect for the molecular recognition in water.     

Synthesis of spirodienones by intramolecular ipso-cyclization of N-methoxy-(4-halogenophenyl)amides using [hydroxy(tosyloxy)iodo]benzene in trifluoroethanol

Spirodienones bearing the 1-azaspiro[4.5]decane ring system have been synthesized from N-methoxy-(4-halogenophenyl)amides by the intramolecular ipso attack of a nitrenium ion generated with [hydroxy(tosyloxy)iodo]benzene in trifluoroethanol.     

Simultaneous application of two or more supported liquid-phase organometallic catalysts: heterogeneous multifunctional reaction systems

Using the form of supported liquid-phase catalysts, two or more homogeneous catalysts can simultaneously be used with retaining their own activities and taking the advantage of catalyst-product separation and catalyst recycling.     

Circular Dichroism Study of the Inclusion-Dissociation Behavior of Complexes between a Molecular Nanotube and Azobenzene Substituted Linear Polymers

We have investigated the inclusion properties of molecular nanotubes composed ofcrosslinked -cyclodextrin. Induced circular dichroism was used to probe theformation and dissociation of complexes between the nanotubes and azobenzenemodified linear polymers. The polymer was poly(ethylene glycol) (PEG), either withor without a hydrophobic alkyl chain.It was found that the inclusion complex betweenthe nanotubes and polymers formed at room temperature, and that the polymers dissociated from the nanotubes with increasing temperature. Further, the polymer with hydrophobic alkyl chain was bound inside the nanotube more strongly and dissociated more abruptly with increasing temperature than its hydrophilic counterpart as expected theoretically.