Preparation of novel organic‐inorganic nanoporous membranes

In this study, the water permeability, the rejection property of sucrose and glucose, the fouling property of humic acid as the foulant for a novel porous fluorinated polyimide membrane made by combining the ion irradiation and plasma treatment have been reported. First, an asymmetric polyimide membrane with a defect‐free and thin skin layer was prepared, then ions on the skin layer were irradiated and the ion‐irradiated layer was treated by plasma to form nanopores in the layer. The asymmetric polyimide membranes with a defect‐free skin layer were irradiated with 50 keV He⁺ at 1 × 10¹⁵ ions/cm², and the irradiated polyimide surfaces were treated by Ar glow discharge. The porous polyimide membrane showed a high water flux and excellent rejection properties and fouling resistance when compared with NTR‐7250, which is commercially available. These findings indicated that the pore size formed on the porous polyimide membrane was effectively controlled by the plasma treatment time and the skin layer thickness. Copyright © 2005 John Wiley & Sons, Ltd.     

“Mössbauer spectroscopic microscope”

A newly developed mapping-technique, “Mössbauer microscopy”, for ⁵⁷Fe probes using a multi capillary X-ray lens (MCX) is tested by observing the two dimensional images of ⁵⁷Fe deposited Si crystals and a stainless steel. The space resolution is reached down to about 20 μm. A possibility of three dimensional microscope is also mentioned.     

The Structure of Zirconium Oxide in Silica Matrix and its Epoxidation Activity

Zirconia-silica composite oxides were prepared by a sol-gel method, and the state of Zr in the silica matrix was analyzed in relation to its activity in the epoxidation of oct-1-ene with t-butyl hydroperoxide. XAFS analysis suggested that Zr in the composite oxides with low Zr content was in the coordinatively less saturated state compared with those in the oxides with higher Zr contents. Epoxidation of oct-1-ene proceeded effectively on the oxides with low Zr contents. The first step of the epoxidation was assumed to be the interaction of t-butyl hydroperoxide with the coordinatively unsaturated site of Zr.     

Synthesis and Crystallochromy of 1,4,7,10‐Tetraalkyltetracenes: Tuning of Solid‐State Optical Properties of Tetracenes by Alkyl Side‐Chain Length

We synthesized a series of 1,4,7,10‐tetraalkyltetracenes using a new 2,6‐naphthodiyne precursor and 2,5‐dialkylfurans as starting materials (alkyl=methyl to hexyl). Surprisingly, the solid‐state color of the tetracenes ranges through yellow, orange, and red. Both yellow and red solids are obtained for the butyl derivative. Optical properties in solution show no marked differences; however, those in the solid state show characteristics that vary with alkyl side‐chain length: methyl, propyl, and pentyl derivatives are orange; ethyl and butyl derivatives are yellow; and another butyl and hexyl derivative are red. X‐ray analyses reveal that the molecular structures are planar, semi‐chair, or chair forms; the chair form takes a herringbone‐like arrangement and the other forms take slipped parallel arrangements. The mechanism of crystallochromy is discussed in terms of molecular structure, crystal packing, and calculations that take account of exciton coupling.     

Chiral arylnickel complexes as highly active initiators for screw‐sense selective living polymerization of 1,2‐diisocyanobenzenes

Optically active chiral organonickel complexes served as efficient chiral initiators for living aromatizing polymerization of 1,2‐diisocyanobenzene derivatives, which afford optically active helical poly(quinoxaline‐2,3‐diyl)s up to 84% s.e. (screw‐sense excess). In comparison with asymmetric polymerization with the corresponding organopalladium initiators, the nickel initiators show a much greater polymerization rate, while the selectivity remains high. The organonickel initiators can be generated in situ from nickel(0) precursors with the corresponding enantiopure (S,S)‐2‐(4,5‐diphenylimidazolin‐2‐yl)phenyl chloride, leading to the convenient synthesis of highly stereo‐controlled poly(quinoxaline‐2,3‐diyl)s. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 898–904, 2010     

Preparation of a Highly Functionalized Cyclopentane Derivative Suitable for the Synthesis of Allosamidin Analogs

Abstract

Methyl 3,6-di-O-benzyl-4-O-benzoyl-2-deoxy-2-methoxycarbonylamino-α-D-glucopyranoside (8) was prepared form D-glucosamine via its 4,6-O-benzylidene derivative. The methyl glycoside moiety of 8 was hydrolyzed in the presence of d-camphorsulfonic acid in acetic acid to give hemiacetal 12. The oxime 14 derived from the latter was subjected to the radical cyclization mediated by tributyltin hydride, providing three types of cyclopentane derivatives. One isomer, 15, having an allosamizoline (2)-like configuration was converted into the N,N′-isopropylidene derivative 3, which is a potential intermediate for the syntheses of analogs of chitinase inhibitor allosamidin (1).     

Small-angle neutron scattering study on the miscibility and concentration fluctuation of hydrogen-bonded polymer blends

Thermal concentration fluctuation in the blends of deuterated poly(ethylene oxide) (dPEO) and poly(vinyl acetate-co-vinyl alcohol) [P(VAc-VOH)] with various VOH contents f_OH were examined by small angle neutron scattering techniques at a fixed blend composition, dPEO/P(VAc-VOH) = 20/80 which is close to the critical composition. Blends at the highest f_OH (=0.35) showed a non-Lorentzian scattering profile: specifically the scattering intensities at the low q (angle) region were suppressed compared to those expected from the random phase approximation (RPA) theory. However, for the blends at lower f_OH (≤0.28), the profiles could be represented by the RPA. Using the RPA we determined effective values of the Flory-Huggins interaction parameter χ_eff as a function of f_OH (=0–0.28). The χ_eff showed the minimum around f_OH = 0.1–0.18 meaning the highest miscibility of the blend at these f_OH. On the basis of the random copolymer theory, we evaluated the three interaction parameters χ_Ac–EO, χ_EO–OH, and χ_Ac–OH separately from the χ_eff(f_OH) and found the order of magnitude; χ_Ac–EO < 0 < χ_EO–OH < χ_Ac–OH. The largest positive χ_Ac–OH showing intrachain interaction in the P(VAc-VOH) copolymer was concluded to be the origin of the enhanced miscibility at around f_OH = 0.1–0.18. On the basis of the Coleman and Painter's theory, the effects of hydrogen bonding on these three χ_A-B were discussed. © 2008 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 46: 2556–2565, 2008     

Magnetic moment and high-field susceptibility of amorphous FeB Invar-type alloys

The saturation magnetization and high-field susceptibility of amorphous Fe_100?xB_x (11 ? x ? 22) alloys have been measured at 4.2 K, 77 K and room temperature in magnetic fields up to 100 kOe. The concentration dependence of the saturation moment per iron atom shows a maximum around 14% boron, while the high-field susceptibility increases remarkably with decreasing boron content. The features are similar to those of crystalline FeNi Invar alloys.