A bridged triptycene-intramolecular diels-alder reaction of 16,19-dimethoxy-[2](9,10)anthraceno[2]paracyclophane

A bridged triptycene was obtained by intramolecular cycloaddition reaction of 16,19-dimethoxy[2](9,10)anthraceno[2]paracyclophane followed by acid-catalyzed elimination of methanol. Internal strain in this molecule was disclosed by X-ray crystallographic analysis.     

Syntheses of some 2-hydroxypyrazine 1-oxides

A series of 2-hydroxypyrazine 1-oxides were prepared from the corresponding chloropyrazines by two methods, including oxidation processes in satisfactory yields. The treatment of 2,3-diphenylpyrazine 1,4-dioxide ( 6 ) led to 2,3-dichloro-5,6-diphenylpyrazine ( 7 ) and 2-chloro-5,6-diphenylpyrazine 1-oxide ( 8 ), and the latter was converted to 5,6-diphenyl-2-hydroxypyrazine 1-oxide ( 9 ) by an alkaline hydrolysis.     

Five new steroidal glycosides,pregnedioside-A, -B,and their three monoacetates,from an Okinawan soft coral of Alcyonium sp.

Five new pregnene-type steroidal glycosides, named pregnedioside -a ($\text{1}$), 4′-O-acetyl-pregnedioside-a ($\text{2}$), 3′-O-acetyl-pregnedioside-a ($\text{3}$), pregnedioside-b ($\text{5}$), and 4′-O-acetyl-pregnedioside-b ($\text{6}$), were isolated from an Okinawan soft coral of Alcyonium sp. and their structures were elucidated. These are rare examples of steroidal gylcosides from soft coral.     

ESR study of linear aliphatic oligoesters under γ-irradiation. I. Paramagnetic species produced in the material by irradiation at 77°K

Paramagnetic species produced in a series of linear aliphatic oligoesters $ [\bond;{\rm O}\bond;({\rm CH}_{\rm 2} {\rm )}_m\bond;{\rm O}\bond;{\rm CO}\bond;({\rm CH}_{\rm 2} {\rm )}_n\bond;{\rm CO\rlap{--} ]}_P $ by γ-irradiation at 77°K was investigated by an ESR method. A predominant doublet observed immediately after γ-irradiation, which has hyperfine splitting of 20–23 gauss, is attributed to a radical anion III. Slight decay of this radical anion is observed by illuminating the sample with visible light at 77°K. A small amount of the radical anion is converted to double triplet, which is assigned to ? (ES)? CH? CH₂? (where ES denotes the ester group), from the result of heat treatment. The conformational angles for the two β-protons in the (6,2) oligoester are determined to be θ₁ = θ₂ = 30°.     

Nano-matrix structure formed by graft-copolymerization of styrene onto natural rubber

Nano-matrix structure was formed by graft-copolymerization of styrene onto urea-deproteinized natural rubber (U-DPNR) latex. The grafted U-DPNR was characterized by FT-IR spectroscopy, ¹H NMR spectroscopy and transmission electron microscopy. Conversion and grafting efficiency of styrene were more than 90% under the best condition of the graft-copolymerization. In transmission electron micrograph of film specimen stained by OsO₄, it was found that natural rubber particle of about 0.5 μm in diameter was dispersed in polystyrene matrix of about 15 nm in thickness. The conversion and grafting efficiency for the grafted U-DPNR were compared with those for a control sample prepared from enzymatic deproteinized natural rubber (E-DPNR) with styrene.     

LASER PHOTOLYSIS STUDIES OF SUPEROXIDE ADDUCTS OF COBALT(II) AND ZINC(II) PORPHYRINS IN DIMETHYLFORMAMIDE

Abstract— Photochemistry of superoxide adducts of cobalt(II) and zinc(II) porphyrins has been studied by laser photolysis. It was found that the former in dimethlformamide photodissociates the superoxide anion radical, O₂^-, with the quantum yield of 0.5 ± 0.05 at the excitation wavelenths 355 and 532 nm, and the latter gives flurescence and the triple state without giving rise to the photodissociation of O₂^-     

Mössbauer spectroscopic study of gamma-ray irradiated potassium phosphate glasses

A Mössbauer spectroscopic study was performed to investigate the effect of γ-ray irradiation on the formation of non-bridging oxygens in the potassium phosphate glasses denoted by the formula x K₂O · (100 ? x)P₂O₅ · 7 Fe₂O₃ (0 ? x ? 50 mol.%). Mössbauer spectra for these glass samples consisted of two kinds of doublets due to Fe²⁺ and Fe³⁺ ions of octahedral symmetries. Only small changes occurred in the Mössbauer parameters as a result of irradiation at room temperature in a dry nitrogen atmosphere, except for the decrease in the absorption area for the Fe²⁺ ions. The decrease in the absorption area was attributed to the electron transfer from the Fe²⁺ ions to the neighboring oxygens. Thermal annealing experiments for a few non-irradiated glass samples indicated that the decrease in the absorption area was confirmed to be due to γ-rays rather than heating during the irradiation.     

Visualization of a Phase Object by Two-Wave Coupling in a Photorefractive Bismuth Silicon Oxide Crystal

We propose a method to visualize a phase object using a locally-controllable image amplification scheme we developed earlier which is based on two-wave coupling in a bismuth silicon oxide (Bi₁₂SiO₂₀, or BSO) crystal. In this method the BSO crystal is used as a phase plate in the configuration of Zernike’s phase contrast imaging system. The principle of the phase-visualization with two-wave coupling is presented. An experimental result to verify the proposed method is shown.     

Photoreactive particle prepared from natural rubber and 1,9‐nonandioldimethacrylate

Photoreactive particle was prepared by graft copolymerization of 1,9‐nonandioldimethacrylate (NDMA) onto deproteinized natural rubber (DPNR) particles in latex stage. First, NDMA was mixed with α‐cyclodextrin (α‐CD) as a coupling agent to form an inclusion complex to stabilize a carbon–carbon double bond of NDMA as a bifunctional monomer. Second, the inclusion complex was graft‐copolymerized onto natural rubber (NR) in latex stage with potassium persulfate (KPS) as an initiator, after deproteinization with urea in the presence of surfactant. A terminal vinyl group of NDMA was used for the graft copolymerization, while the other remained in the resulting polymer, due to the coupling effect of the α‐CD. The products, after washing α‐CD out, were characterized by FTIR, X‐ray diffraction (XRD), ¹H NMR and solid‐state ¹³C NMR measurements. The amount of residual carbon–carbon double bond after graft copolymerization was investigated in relation to the amount of rubber and reaction temperature. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 4111–4118, 2009