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51.
Akimoto Tachibana Masahiko Koizumi Iwao Okazaki Hiroyuki Teramae Tokio Yamabe 《Theoretical chemistry accounts》1987,71(1):7-19
The non- and fluorine-substituted singlet carbonyl ylides are studied by using ab initio MCSCF calculations. The thermodynamic stability of the carbonyl ylides and the intramolecular stability to isomerization or fragmentation reaction coordinates is demonstrated in terms of the topological structure of the ab initio potential energy surfaces. The allylic resonance is found to be dynamically unstable, considering out-of-plane vibrational mode. The instability is studied by the symmetries of the low-lying excitations out of the MCSCF wave function. 相似文献
52.
Naoki Asao 《Tetrahedron letters》2005,46(1):27-30
The HfCl4 catalyzed polymerization of allyl(4-ethynylphenyl)dimethylsilane (1a) proceeded smoothly to give poly[dimethyl-(1,4-pentadienyl)phenylsilane] (2a), and the HfCl4 catalyzed reaction of 1-allyl-2-(4-ethynyphenyl)-1,1,2,2-tetramethyldisilane (1b) afforded poly[1,1,2,2-tetramethyl-1-(1,4-pentadienyl)-2-phenyldisilane] (2b). These polymerization reactions proceeded via the stereoselective trans-allylsilylation of the 4-ethynyl group attached to the aromatic ring. 相似文献
53.
54.
Qi ZM Matsuda N Santos J Yoshida T Takatsu A Kato K 《Journal of colloid and interface science》2004,271(1):249-253
Broadband, time-resolved optical waveguide (OWG) spectroscopy has been used for in situ, real-time investigation into the self-assembly of metal nanoparticle monolayers. The OWG spectroscopy makes it possible to use the transverse electric (TE) and transverse magnetic (TM) modes to measure surface plasmon absorption of immobilized metal nanoparticles in two directions, parallel and normal to the waveguide surface. Therefore, this technique can provide direction-dependent information on the metal nanoparticles at the interface. In this paper, a 50-microm-thick glass plate was used as a slab waveguide and the kinetics of Au nanoparticle adsorption on a hemoglobin-functionalized glass substrate was examined in the early stage of self-assembly. The findings show that with the TE mode the surface plasmon resonance (SPR) behavior for immobilized Au nanoparticles is different from that with the TM mode. 相似文献
55.
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57.
Ikuta A Mizuta N Kitahata S Murata T Usui T Koizumi K Tanimoto T 《Chemical & pharmaceutical bulletin》2004,52(1):51-56
Six novel branched beta-cyclodextrins (betaCDs) having beta-D-galactose residues on the non-reducing terminal of the sugar side chains, namely 6(1),6(4)-di-O-(beta-D-galactosyl)-betaCD (10), 6-O-(beta-D-galactosyl)-betaCD (11), 6(1),6(4)-di-O-(beta-lactosyl)-betaCD (14), 6-O-(beta-lactosyl)-betaCD (15), 6(1),6(4)-di-O-(4'-O-beta-D-galactosyl-beta-lactosyl)-betaCD (18), and 6-O-(4'-O-beta-D-galactosyl-beta-lactosyl)-betaCD (19), were chemically synthesized using the trichloroacetimidate method. The reaction products were separated by HPLC on an amino column into dibranched and monobranched betaCDs. Their structures were confirmed by mass spectrometry (MS) and two-dimensional (2D) NMR spectroscopic analysis. To study the length of the sugar side chains attached to the CD ring, which leads to differences in the functions of the branched CDs, interactions of these compounds with peanut (Arachis hypogaea) agglutinin (PNA) were investigated using an optical biosensor and an inhibition assay based on hemagglutination. The results showed that all branched betaCDs interacted with PNA, and the binding affinity was 18>14>10 and 19>15>11 when the derivatives were compared on the basis of side chain length. 相似文献
58.
Oscillating frequencies of a piezoelectric crystal were measured in various solutions. One side of the crystal surface was coated with a silicon sealant. This coating was useful for measuring the oscillation of crystals in solutions for a wide range of products of density (?) and viscosity (η) and in electrolyte solutions. For measurement in solutions, the frequency change depended on the circuit used, whereas for measurements in air the circuit did not influence the frequency change. All experimental data showed that the frequency change from pure water, ΔFw, followed ΔFw = ? K(√?η ? √?wηw) except for electrolyte and polymer solutions, where K is a proportionality constant, ηw the density of pure water and ηw the viscosity of water. 相似文献
59.
Naoki Noma Saori Yamazaki Noboru Tohge 《Journal of Sol-Gel Science and Technology》2004,31(1-3):253-256
ZrO2 gel films were prepared from zirconium tetra-n-butoxide chemically modified with one of hydroxyl-substituted aromatic ketones and 1′-hydroxy-2′-acetonaphthone, by the sol-gel method. The obtained gel film showed an absorption band, characteristic of the π-π* transition of chelate ring, at around 410 nm. The band was shifted to longer wavelength region than those for the gel films using β-diketones. The reason is thought that the hydroxyl-substituted aromatic ketone has π-electron system to form the condensed chelate ring. The absorption band associated with the chelate ring gradually decreased in intensity with UV-irradiation using a high pressure mercury lamp. This indicates that the chelate ring dissociates by the UV-irradiation and that the gel film exhibits photosensitivity. Utilizing the photosensitivity, fine patterns (about 1 μm) could be fabricated by UV-irradiation through a mask and leaching. 相似文献
60.
Yoshitsugu Arai Shū-ichi Kuwayama Yoshio Takeuchi Toru Koizumi 《Tetrahedron letters》1985,26(50):6205-6208
The Diels-Alder reaction of a novel chiral dienophile, alkyl ()-2--tolylsulfinylacrylates 1 with anthracene and cyclopentadiene showed high diastereoselectivity under the chelation controlled condition. 相似文献