Diene complexes of early transition metals: ideas and progresses at Osaka University

Historical perspectives for the chemistry of diene complexes of early transition metals developed at Osaka University in the period after 1970s were reviewed briefly and personally. Preparative chemistry of this field commenced from the magnesium-diene 1:1 compounds and quickly extended to almost all the early transition metals. By the studies operated together with other researchers, unique features of these diene complexes, especially their bonding and structure, selective reactions, and catalysis performances are described.     

Permeability,permselectivity, and penetrant‐induced plasticization in fluorinated polyimides studied by positron lifetime measurements

The ortho‐positronium (o‐Ps) lifetime τ₃ and its intensity I₃ in various fluorinated polyimides were determined by the positron annihilation technique and were studied with the spin–lattice relaxation time T₁ and the propylene permeability, solubility, diffusivity, and permselectivity for propylene/propane in them. τ₃, I₃, and the distribution of τ₃ changed when the bulky moieties in the polyimides were changed. The polyimides, having both large τ₃ and I₃ values, exhibited a short T₁ and a high permeability with a low permselectivity. The propylene permeability and diffusivity were exponentially correlated with the product of I₃ and the average free‐volume hole size estimated from τ₃. In highly plasticized states induced by the sorption of propylene, the permeability increased with the propylene pressure in excellent agreement with the change in the free‐volume hole properties probed by o‐Ps. The large and broad distribution of the free‐volume holes and increased local chain mobility for the 2,2‐bis(3,4‐decarboxyphenyl) hexafluoropropane dianhydride‐based polyimides are thought to be important physical properties for promoting penetrant‐induced plasticization. These results suggest that o‐Ps is a powerful probe of not only the free‐volume holes but also the corresponding permeation mechanism and penetrant‐induced plasticization phenomenon. © 2003 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 41: 308–318, 2003     

Synthesis and characterization of model 3‐miktoarm star copolymers of poly(dimethylsiloxane) and poly(2‐vinylpyridine)

3‐Miktoarm star copolymers, 3μ‐D₂V, with two poly(dimethylsiloxane) (PDMS) and one poly(2‐vinylpyridine) (P2VP) arm, were synthesized by using anionic polymerization–high vacuum techniques and (chloromethylphenylethyl)methyl dichlorosilane, heterofunctional linking agent, with two SiCl groups and one CH₂Cl group. The synthetic strategy involves the selective reaction of the two ? SiCl groups with PDMSOLi living chains, followed by reaction of the remaining chloromethyl group with P2VPLi. Combined molecular characterization results (size exclusion chromatography, membrane osmometry, and ¹H NMR spectroscopy) revealed a high degree of structural and compositional homogeneity. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 614–619, 2006     

Lithographic design of photosensitive polyarylates based on reaction development patterning

The factors affecting pattern‐forming properties in reaction development patterning were examined with polyarylates with various bisphenol moieties. The developability of the photosensitive polyarylates was dependent on the properties of the subtituent (R) in the bisphenol moieties. The development time decreased in the following order: R?C(CH₃)₂ > fluorenyl unit ? phenolphthalein unit > C(CF₃)₂ > SO₂. This order agreed with that of the reactivity between the polyarylates and ethanolamine, and these orders can be explained by pK_a of the bisphenol used to prepare the polyarylates. The development with NH₂? R′? OH resulted in successful positive‐tone pattern formation. However, pattern formation with the developers containing NH₂? R′? OCH₃ was unsuccessful. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 2694–2706, 2006     

Preparation and certification of the new reference materials; plastics (disk form, JSAC 0621-0625) for determination of mercury using x-ray fluorescent analysis.

The Japan Society for Analytical Chemistry has developed some new plastic certified reference materials (CRMs) for the analysis of mercury in polyester disks using XRF analysis. These CRMs (named as JSAC 0621-0625) were prepared by casting polyesters including a toluene solution of organometallic compounds as a standard. Concentrations of the five levels of mercury ranged from 0 to 250 mg/kg. Homogeneity tests of prepared disks had shown excellent results. Interlaboratory comparison study for the certification was performed by 15 laboratory participants. The z-scores in robust statistical method was applied for the evaluation of outliers. The certified values were assigned after discarding outliers. The uncertainties of certified values were determined as the confidence levels of 95%.     

Diastereoselective synthesis of new psi[(E)-CH=CMe]- and psi[(Z)-CH=CMe]-type alkene dipeptide isosteres by organocopper reagents and application to conformationally restricted cyclic RGD peptidomimetics

Diastereoselective synthesis of new psi[(E)-CH=CMe]- and psi[(Z)-CH=CMe]-type alkene dipeptide isosteres corresponding to dipeptides having one N-methylamino acid, and application to bioactive peptides, are described. In a key reaction introducing the chiral alpha-alkyl group of the isosteres, organocopper-mediated alkylation of syn-beta-methylated gamma-mesyloxy-alpha,beta-enoate 26a afforded E- and Z-isomers of anti-S(N)2' products in a solvent-dependent manner. The resulting two isosteres, D-Phe-psi[(E)-CH=CMe]-L-Val 27a and D-Phe-psi[(Z)-CH=CMe]-L-Val 28b, which corresponded to trans- and cis-conformers of D-Phe-L-MeVal, respectively, were utilized in a structure-activity relationship study on cyclic RGD peptides 1 and 2, in company with a psi[(E)-CH=CH]-type alkene dipeptide isostere, D-Phe-psi[(E)-CH=CH]-L-Val. The cyclic isostere-containing pseudopeptides 3, 4, and 40 were synthesized and biological activity against integrin alpha(V)beta(3) and alpha(IIb)beta(3) receptors were also evaluated.     

Construction of a new multi-turn time-of-flight mass spectrometer

A new type of multi-turn time-of-flight mass spectrometer was constructed, consisting of four cylindrical electric sectors and 28 electric quadrupole lenses, the size of the vacuum chamber being 60 x 70 x 20 cm. It was demonstrated that the mass resolution can be increased according to the number of cycles of the ions through the ion optical system.     

Dielectric behavior of polyethyleneoxide (polyox)

Ohne Zusammenfassung     

Regiospecific cycloaddition reactions using functionalized isoprenylsilane and related compounds

1-Alkoxy-3-trimethylsilylmethyl- and 1-alkoxy-3-trimethylsilyl-l,3-butadienes ($\text{1}$) were newly prepared. The cycloaddition reactions of $\text{1}$ with various dienophiles including heterodienophiles were found to proceed very smoothly in a perfectly regiospecific mode.