Gas permeation of porous organic/inorganic hybrid membranes

Selective gas permeation of porous organic/inorganic hybrid membranes via sol-gel route and its thermal stability are described. Separation performance of the hybrid membrane was improved compared with porous membranes governed by the Knudsen flow, and gas permeability was still much higher than that through nonporous membranes. Additionally, it was shown that these membranes were applicable at higher temperatures than organic membranes.SEM observation demonstrated that the thin membrane was crack-free. Nitrogen physisorption isotherms showed the pore size was in the range of nanometers. Gas permeability through this membrane including phenyl group was in the range of 10^–8 [cc(STP) cm/(cm² s cmHg)] at 25°C. The ratios of O₂/N₂ and CO₂/N₂ were 1.5 and 6.0, respectively, showing the permeation was not governed by the Knudsen flow. The permeability decreased as the temperature increased. Furthermore, the specific affinity between gas molecules and surface was observed not only in the permeation data of the hybrid membranes but in the physisorption data. These results suggested that the gas permeation through the hybrid membrane was governed by the surface flow mechanism.Thermal analysis indicated that these functional groups were still stable at higher temperatures. The phenyl group especially remained undamaged even at 400°C.     

Production of poly(methyl methacrylate) particles by dispersion polymerization with mercaptopropyl terminated poly(dimethylsiloxane) stabilizer in supercritical carbon dioxide

Poly(methyl methacrylate) (PMMA) particles were produced by dispersion polymerization of methyl methacrylate in the presence of mercaptopropyl terminated poly(dimethylsiloxane) (MP-PDMS) in supercritical carbon dioxide at about 30 MPa for 24 h at 65 °C. The particle diameter could be controlled in a size range of submicron to micron by varying MP-PDMS concentration. The MP-PDMS worked as not only a chain transfer agent but also a colloidal stabilizer, which was named tran stab.Part CCLI of the series Studies on suspension and emulsion     

A novel redox system consisting of π-conjugated polymers and transition metals

Coordination of π-conjugated polymers to transition metals constructs a novel redox system due to interchangeable various oxidation states of the polymers, which permits transition metals to interact with each other through a π-conjugate chain. The redox characteristics were found to depend on the electronic interaction with metals and the doping. A combination of copper(II) or iron(III) chloride and polyanilines afforded the complex catalysts with the higher oxidation capability for dehydrogenative oxidation. A catalytic system was also realized in the transition-metal-induced oxidation reaction, in which π-conjugated polymers serve as redox-active ligands participating in the reversible redox cycle. The Wacker oxidation of terminal olefins proceeded catalytically in the presence of a catalytic amount of polyaniline or polypyrrole derivative under oxygen.     

Syntheses, structures, and reactivities of homometallic rare-earth-metal multimethyl methylidene and oxo complexes

Unsolvated, trinuclear, homometallic, rare-earth-metal multimethyl methylidene complexes [{(NCN)Ln(μ(2)-CH(3))}(3)(μ(3)-CH(3))(μ(3)-CH(2))] (NCN = L = [PhC{NC(6)H(4)(iPr-2,6)(2)}(2)](-); Ln = Sc (2a), Lu (2b)) have been synthesized by treatment of [(L)Ln{CH(2)C(6)H(4)N(CH(3))(2)-o}(2)] (Ln = Sc (1a), Lu (1b)) with two equivalents of AlMe(3) in toluene at ambient temperature in good yields. Treatment of 1 with three equivalents of AlMe(3) gives the heterometallic trinuclear complexes [(L)Ln(AlMe(4))(2)] (Ln = Sc (3a), Lu (3b)) in good yields. Interestingly, 2 can also be generated by recrystallization of 3 in THF/toluene, thereby indicating that the THF molecule can also induce C-H bond activation of 2. Reaction of 2 with one equivalent of ketones affords the trinuclear homometallic oxo-trimethyl complexes [{(L)Ln(μ(2) -CH(3))}(3) (μ(3)-CH(3))(μ(3)-O)] (Ln = Sc(4a), Lu(4b)) in high yields. Complex 4b reacts with one equivalent of cyclohexanone to give the methyl abstraction product [{(L)Lu(μ(2) -CH(3) )}(3) (μ(3) -OC(6)H(9))(μ(3)-O)] (5b), whereas reaction of 4b with acetophenone forms the insertion product [{(L)Lu(μ(2)-CH(3))}(3){μ(3)-OCPh(CH(3))(2)}(μ(3)-O)] (6b). Complex 4a is inert to ketone under the same conditions. All these new complexes have been characterized by elemental analysis, NMR spectroscopy, and confirmed by X-ray diffraction determination.     

Asymmetric synthesis of α,α-disubstituted α-amino alcohol derivatives

Herein we report the asymmetric synthesis of α,α-disubstituted α-amino alcohol derivatives 22, 25 and 26, key intermediates of a novel immunomodulator, using Seebach’s method. This synthetic method can be applied to the large scale synthesis of chiral sphingosine 1-phosphate-1 (S1P₁) receptor agonists, with significant improvements to the previously reported method with regard to the reaction temperature.     

QUATERNARY STRUCTURE OF PEA PHYTOCHROME I DIMER STUDIED WITH SMALL-ANGLE X-RAY SCATTERING and ROTARY-SHADOWING ELECTRON MICROSCOPY

Abstract— The quaternary structure of pea phytochrome type I (PI) dimer in the red-light-absorbing form was studied by small-angle X-ray scattering (SAXS) technique and rotary-shadowing electron microscopy. Structural parameters for PI 114 kDa chromopeptide dimer and its tryptically digested N-terminal 59 kDa chromopeptide monomer, such as average electron density, molecular volume and the second moment of electron density distribution, were determined in terms of SAXS using the contrast variation method. Furthermore, by means of model simulation for the scattering profiles of the chromopeptides, most plausible structural models for both peptides were constructed. The distance between the chromophoric domains was estimated to be about 70 A in the resultant model for 114 kDa chromopeptide dimer. Furthermore, the model was consistent with the electron-micrographic images of both the intact PI dimer and the PI 114 kDa chromopeptide dimer, so that the N-terminal 7 kDa fragment did not significantly contribute the low-resolution images of the dimer.     

Preparation of multihollow polymer particles by seeded emulsion polymerization using seed particles with incorporated nonionic emulsifier

Emulsion polymerizations of styrene using poly(oxyethylene) nonylphenyl ether nonionic emulsifier were carried out at different emulsifier and initiator (potassium persulfate, KPS) concentrations to prepare polystyrene (PS) seed particles with incorporated nonionic emulsifier. Seeded emulsion polymerizations of styrene using the PS seed particles with different amounts of incorporated emulsifier were carried out to develop a novel method for the preparation of multihollow particles. When seed particles with a small amount of incorporated emulsifier were used, non-hollow spherical particles were prepared. However, multihollow particles were obtained in the case of seed particles with a large amount of incorporated emulsifier. Moreover, the higher the initiator concentration in the preparation of seed particles, the more effectively were hollow particles prepared. On the basis of the above results, a mechanism for the formation of multihollow structure was suggested.     

Periodic change of viscosity and density in an oscillating chemical reaction

It was found that the periodic change of the solution viscosity and density was generated in the Belousov-Zhabotinsky (BZ) reaction. This rhythmic phenomenon was observed in both the iron catalyst [[Fe(Phen)(3)](2+)-[Fe(Phen)(3)](3+)] and the cerium catalyst [Ce(III)-Ce(IV)] system, where the solution viscosity and density were synchronized with the redox potential in the in-phase mode. However, the time delay existed between the redox potential and the solution viscosity and density. The behavior of the BZ reaction was also monitored in the presence of the nonionic surfactant. This experiment revealed that, beyond the critical micelle concentration, the phase between the redox potential and the solution viscosity and density was synchronized into the antiphase mode. We suggested that the variation of the catalyst drove the oscillation of the solution viscosity and density in the BZ reaction.