Synthesis of Orthorhombic Mo‐V‐Sb Oxide Species by Assembly of Pentagonal Mo6O21 Polyoxometalate Building Blocks

Mix and match : The pentagonal [Mo₆O₂₁]^n? polyoxomolybdate building block assembles with other sources of Mo, V, and Sb ions to form an orthorhombic Mo‐V‐Sb oxide. The first single‐crystal X‐ray analysis of an orthorhombic Mo–V‐based oxide, a promising catalyst for light alkane selective oxidation known as the “M1 phase”, revealed the structure of the compound.

     

The Ricci tensor and structure Jacobi operator of real hypersurfaces in a complex projective space

Let M be a real hypersurface with almost contact metric structure ${(\phi, \xi, \eta, g)}$ in a complex projective space ${P_{n}\mathbb{C}}$ . A Real hypersurface M is said to be a Hopf hypersurface if ξ is principal. In this paper we investigate real hypersurfaces of ${P_{n}\mathbb{C}}$ whose Ricci tensors S satisfy ${\nabla_{\phi\nabla_{\xi}\xi}S = 0}$ . Under some further conditions we characterize Hopf hypersurfaces of ${P_{n}\mathbb{C}}$ .     

Studies on the chemical transformations of rotenoids. 6 Synthesis and antitumor‐promoting activity of benzofuro[2,3‐d]pyridazines fused with 1,2,4‐triazole, 1,2,4‐triazine and 1,2,4‐triazepine

[1]Benzofuro[2,3‐d]pyridazines fused with 1,2,4‐triazole ( 6 and 7 ), 1,2,4‐triazine ( 8–10 ) and 1,2,4‐tri‐azepine (12) were prepared by the ring closure of 4‐hydrazino‐[1]benzofuro[2,3‐d]pyridazine ( 5 ), derived from naturally occurring rotenone. Compounds ( la and lb ) exhibited significant inhibitory activity against 12‐O‐tetradecanoylphorbol 13‐acetate (TPA)‐induced Epstein‐Barr virus early antigen (EBA‐EA) activation in Raji cells. In contrast, the fused [1]benzofuro[2,3‐d]pyridazines except 6c and 8 were quite inactive.     

Synthesis and potential central nervous system stimulant activity of 5,8‐methanoquinazolines and bornano‐triazines fused with imidazole and pyrimidine

Starting from 3‐chloro‐5,8‐methanoquinazoline 1 and 3‐chloro‐bornano[1,2,4]triazine 7 , the novel 5,8‐methanoquinazolines 5a‐b and bornano[1,2,4]triazines 10a‐b fused with imidazole and pyrimidine were prepared. None of these compounds showed any satisfactory central nervous system stimulant activities.     

Sustained saturation in a free-electron laser oscillator at perfect synchronism of an optical cavity.

The first observation of sustained saturation in a free-electron laser (FEL) oscillator at perfect synchronism of an optical cavity is presented. A simultaneous measurement of FEL power and absolute detuning length of the optical cavity ( deltaL) has clearly shown that the FEL efficiency becomes maximum at deltaL = 0.0+/-1 microm, although it has been considered that only a transient state exists at deltaL = 0 due to the well-known laser lethargy effect. The observed efficiency detuning curve is well reproduced by our numerical simulation including a small shot-noise effect.     

Synthesis of new macro-azo-initiators having two kinds of azo linkages in repeating unit and block copolymerization by two-step radical polymerization initiated with them

Two kinds of new macro-azo-initiator (MAI) having dual decomposition temperatures were synthesized by polycondensation between 4,4′-azobis-4-cyanopentanoyl chloride (ACPC) and 2,2′-azobis-2-cyanopentanol (ACPO) (MAI [2A]), and between ACPC and 2,2′-azobis-2-methyl-N-2-hydroxyethylpropionamide (AHPA) (MAI [2B]). MAI [2A] and [2B] were compared with MAI [1] having a single decomposition temperature synthesized by polycondensation between ACPC and bisphenol-Z. Two step polymerization of styrene and methyl methacrylate initiated with MAI [1], [2A], and [2B] was carried out. It was confirmed that the new MAI [2A] and [2B] initiated effectively at each step of polymerization due to their dual decomposability, resulting in higher conversion of the comonomers to yield block copolymers than the case initiated with MAI [1]. © 1997 John Wiley & Sons, Inc.     

A novel promoter, heteropoly acid, mediated chemo- and stereoselective sulfoxide glycosidation reactions

The chemo- and stereoselective glycosidations of sulfinylglycosides and alcohols using a heteropoly acid, H₃PW₁₂O₄₀, as a new promoter have been developed.     

Synthesis of [1,2,5]selena(or thia)diazolo[3,4‐e][1,4]diazepines, [1,2,5]selena(or thia)diazolo[3,4‐e][1,4]oxazepines and [1,2,5]selena(or thia)diazolo[3,4‐c] [1,2,6]thiadiazines

Novel heterocycles [1,2,5]selenadiazolo[3,4‐e][1,4]diazepines 3a‐c , [1,2,5]thiadiazolo[3,4‐e]‐[1,4]diazepines 7a‐c , [1,2,5]selenadiazolo[3,4‐e][1,4]oxaepines 4a,b , [1,2,5]thiadiazolo[3,4‐e]‐[1,4]oxazepines 9a‐c and [1,2,5]selena(or thia)diazolo[3,4‐c][1,2,6]thiadiazines 10a,b were synthesized starting form 4,6‐dimethyl[1,2,5]se]enadiazolo[3,4‐d]pyrimidine‐5,7(4H,6H)‐dione 1 or 4,6‐dimethyl‐[1,2,5]thiadiazolo[3,4‐d]pyrimidine‐5,7(4H,6H)‐dione 5 .     

Sorption and transport of hydrocarbon and perfluorocarbon gases in poly(1‐trimethylsilyl‐1‐propyne)

Pure gas solubility and permeability of H₂, O₂, N₂, CO₂, CH₄, C₂H₆, C₃H₈, CF₄, C₂F₆, and C₃F₈ in poly(1‐trimethylsilyl‐1‐propyne) (PTMSP) were determined as a function of pressure at 35°C. Permeability coefficients of the perfluorinated penetrants are approximately an order of magnitude lower than those of their hydrocarbon analogs, and lower even than those of the permanent gases. In striking contrast to hydrocarbon penetrants, PTMSP permeability to fluorocarbon penetrants decreases with increasing penetrant size. This unusual size‐sieving behavior in PTMSP is attributed to low perfluorocarbon solubilities in PTMSP coupled with low diffusion coefficients relative to those of their hydrocarbon analogs. In general, perfluorocarbon penetrants are less soluble than their hydrocarbon analogs in PTMSP. The difference in hydrocarbon and perfluorocarbon solubilities in high free volume, hydrocarbon‐rich PTMSP is much smaller than in hydrocarbon liquids and liquidlike polydimethylsiloxane. The low solubility of perfluorocarbon penetrants is ascribed to the large size of the fluorocarbons, which inhibits their dissolution into the densified regions of the polymer matrix and reduces the number of penetrant molecules that can be accommodated in Langmuir sites. From the permeability and sorption data, diffusion coefficients were calculated as a function of penetrant concentration. With the exception of H₂ and the C₃ analogs, all of the penetrants exhibit a maximum in their concentration‐dependent diffusion coefficients. Resolution of diffusion coefficients into a mobility factor and a thermodynamic factor reveals that it is the interplay between these two terms that causes the maxima. The mobility of the smaller penetrants (H₂, O₂, N₂, CH₄, and CO₂) decreases monotonically with increasing penetrant concentration, suggesting that the net free volume of the polymer–penetrant mixture decreases as additional penetrant is added to PTMSP. For larger penetrants mobility either: (1) remains constant at low concentrations and then decreases at higher penetrant concentrations (C₂H₆, CF₄, and C₂F₆); (2) remains constant for all concentrations examined (C₃H₈); or (3) increases monotonically with increasing penetrant concentration (C₃F₈). Presumably these results reflect the varying effects of these penetrants on the net free volume of the polymer–penetrant system. © 2000 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 38: 273–296, 2000     

Synthesis of silicon‐based polymer films by excimer laser‐induced photo‐reaction of phenylsilane and methylphenylsilane

The synthesis of silicon‐based polymer films was studied by excimer laser (248 nm)‐induced photo‐reaction of phenylsilane and methyl‐phenylsilane at reduced pressure. IR and UV–VIS results showed that the films were composed of Si–C network structures with phenyl rings. Copyright © 2000 John Wiley & Sons, Ltd.