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961.
Masashi Shigenobu Kazuhiro Takenaka Hiroaki Sasai 《Angewandte Chemie (International ed. in English)》2015,54(33):9572-9576
A palladium‐catalyzed direct arylation of isoxazoles with aryl iodides has been achieved. The C H bond at the 5‐position is activated selectively to give coupling products in moderate to good yields. This direct arylation was applied to the synthesis of a spiro‐type chiral ligand, which proved to be most effective to the palladium‐catalyzed tandem cyclization of a dialkenyl alcohol. 相似文献
962.
We examine a class of Grushin type operators Pk where k∈N0 defined in (1.1). The operators Pk are non-elliptic and degenerate on a sub-manifold of RN+?. Geometrically they arise via a submersion from a sub-Laplace operator on a nilpotent Lie group of step k+1. We explain the geometric framework and prove some analytic properties such as essential self-adjointness. The main purpose of the paper is to give an explicit expression of the fundamental solution of Pk. Our methods rely on an appropriate change of coordinates and involve the theory of Bessel and modified Bessel functions together with Weber's second exponential integral. 相似文献
963.
Mitsuhiro Okimoto Takashi Yoshida Masayuki Hoshi Kazuyuki Hattori Masashi Komata Kenta Tomozawa 《合成通讯》2013,43(19):3320-3328
Several ketone allylhydrazones were electrochemically oxidized in methanol in the presence of sodium methoxide and potassium iodide to afford the corresponding azines. The electro-oxidation involves formation of a new carbon–nitrogen double bond between an allylic carbon atom and the nitrogen atom of a hydrazone to afford a conjugated system. Optimal yields were obtained when 0.5 equivalents of sodium methoxide and a catalytic amount of potassium iodide were used as the supporting electrolyte at room temperature. Presumably, the electro-oxidation involves a two-electron oxidation process where the iodide ion functions as electron carrier. 相似文献
964.
Tomoya Saito Hiroshi Kakehi Yoshihiro Kato Masashi Miura Norifumi Isu Hideo Sawada 《先进技术聚合物》2013,24(6):532-540
Calcium chloride reacted with sodium carbonate in the presence of a variety of fluoroalkyl end‐capped oligomers such as fluoroalkyl end‐capped acrylic acid oligomer (RF‐[ACA]n‐RF), 2‐methacryloyloxyethanesulfonic acid oligomer (RF‐[MES]n‐RF), N,N‐dimethylacrylamide oligomer (RF‐[DMAA]n‐RF) and acryloylmorpholine oligomer (RF‐[ACMO]n‐RF) to afford the corresponding fluorinated oligomers/calcium carbonate composites. Each fluorinated oligomer/calcium carbonate composite thus obtained is nanometer size‐controlled very fine particles (25–114 nm) possessing a good dispersibility and stability in a variety of solvents including water. Thermal stability of these fluorinated calcium carbonate nanocomposites was studied by thermogravimetic analyses measurements. Fluorinated oligomes, in which the theoretical oligomer content in the composites is 19%, were able to give no weight loss corresponding to the content of oligomer in each case even after calcination at 800 °C. On the other hand, a slight weight loss corresponding to the contents of oligomers in the composites after calcination at 800 °C was observed in RF‐(MES)n‐RF/, RF‐(DMAA)n‐RF/ and RF‐(ACMO)n‐RF/calcium carbonate nanocomposites, in which the theoretical contents of the oligomers were 36–53%, although RF‐(ACA)n‐RF/calcium carbonate nanocomposites gave a clear weight loss corresponding to the contents of oligomer under similar conditions. Fluorinated oligomers/calcium carbonate nanocomposites possessing no weight loss at 800 °C were applied to the surface modification of poly(methyl methacrylate) (PMMA) to exhibit a good oleophobicity imparted by fluorines on the surfaces. Interestingly, these fluorinated calcium carbonate nanocomposites after calcination at 800 °C were found to exhibit the similar oleophobic characteristic on the modified PMMA surfaces as well as that of the nanocomposites before calcination. Copyright © 2013 John Wiley & Sons, Ltd. 相似文献
965.
966.
Masashi Nakamura Kenji Oqmhula Keishu Utimula Miharu Eguchi Kengo Oka Kenta Hongo Ryo Maezono Kazuhiko Maeda 《化学:亚洲杂志》2020,15(4):540-545
The Pb‐V oxyhalide apatite compounds Pb5(VO4)3X (X=F, Cl, Br, I) were successfully synthesized using a facile solution method and studied with respect to their structural/optical characteristics and electronic band structures. UV‐visible diffuse reflectance spectroscopy, electrochemical analysis and first‐principles calculations showed that the synthesized apatites behaved as n‐type semiconductors, with absorption bands in the UV‐visible region that could be assigned to electron transitions from the valence band to a conduction band formed by hybridized V 3d and Pb 6p orbitals. Among the apatites examined, Pb5(VO4)3I had the smallest band gap of 2.7 eV, due to an obvious contribution of I 5p orbitals to the valence band maximum. Based on its visible light absorption capability, Pb5(VO4)3I generated a continuous anodic photocurrent under visible light (λ>420 nm) in a solution of 0.1 m NaI in acetonitrile. 相似文献
967.
968.
Sujuan Guo Takahumi Ogasawara Tomoya Saito Hiroshi Kakehi Yoshihiro Kato Masashi Miura Norifumi Isu Hideo Sawada 《Colloid and polymer science》2013,291(12):2947-2957
Fluoroalkyl end-capped vinyltrimethoxysilane oligomer/anatase titanium oxide nanocomposite-encapsulated low molecular weight aromatic compounds [RF-(VM-SiO2)n-RF/an-TiO2/Ar-H] were prepared by the sol–gel reactions of the corresponding oligomer in the presence of anatase titanium oxide nanoparticles (an-TiO2) and the aromatic compounds such as bisphenol A [BPA], 1,1′-bi(2-naphthol) [BINOL], and fullerene under alkaline conditions. Thermogravimetric analyses measurements show that RF-(VM-SiO2)n-RF/an-TiO2 nanocomposite-encapsulated BPA and BINOL, in which the theoretical contents in the composites are 25?~?32 %, were found to give no weight loss corresponding to the contents of these aromatic compounds even after calcination at 800 °C. On the other hand, the corresponding nanocomposite-encapsulated fullerene exhibited weight loss behavior related to the presence of fullerene under similar conditions; however, UV–vis spectra showed the presence of the residual fullerene in the composites even after calcination. An-TiO2 in these fluorinated nanocomposites can keep its crystalline structure without phase transformation into rutile even after calcination at 1,000 °C, although the parent an-TiO2 nanoparticles underwent a complete phase transformation into rutile under similar conditions. Notably, RF-(VM-SiO2)n-RF/an-TiO2/Ar-H nanocomposites can give a good photocatalytic activity even after calcination at 1,000 °C for the decolorization of methylene blue under UV light irradiation. More interestingly, these fluorinated nanocomposites before and after calcination were found to exhibit a higher photocatalytic activity at the initial UV light irradiation from 1 to 3 min than that of the corresponding RF-(VM-SiO2)n-RF/an-TiO2 nanocomposites under similar conditions. Figure
Encapsulated BPA and BINOL in the nanocomposites exhibit no weight loss even after calcination at 800 °C, and RF-(VM-SiO2)n-RF/an-TiO2/Ar-H nanocomposites before and after calcination at 1,000 °C can give a higher photocatalytic activity than that of RF-(VM-SiO2)n-RF/an-TiO2 nanocomposites. Notably, the photocatalytic activity of RF-(VM-SiO2)n-RF/an-TiO2/C60 nanocomposites after calcination increased by about 2.5-fold, compared with that of RF-(VM-SiO2)n-RF/an-TiO2 nanocomposites. 相似文献
969.
Masashi Ito Prof. Hirotomo Nishihara Kentaro Yamamoto Dr. Hiroyuki Itoi Dr. Hideki Tanaka Akira Maki Prof. Minoru T. Miyahara Dr. Seung Jae Yang Prof. Chong Rae Park Prof. Takashi Kyotani 《Chemistry (Weinheim an der Bergstrasse, Germany)》2013,19(39):13009-13016
Nanoporous materials, such as zeolites, activated carbons, and metal–organic frameworks (MOFs), are peculiar platforms in which a variety of guest molecules are stored, reacted, and/or separated. The size of the nanopores is essential to realize advanced functions. In this work, we demonstrate a very simple but innovative method for the control of nanopore size, that is, reversible and continuous control by mechanical force loaded to soft nanoporous materials. The elastic properties of several microporous materials, including zeolites, zeolite‐templated carbon (ZTC), activated carbon, and MOFs (e.g., ZIF‐8), are examined and it is found that ZTC is a material that is suitable for the aforementioned idea thanks to its extraordinary soft properties compared to the others. The original pore size of ZTC (1.2 nm) can be contracted to 0.85 nm by using a relatively weak loading force of 135 MPa, whereas the other microporous materials barely contracted. To demonstrate the change in the physical properties induced by such artificial deformation, in situ gas adsorption measurements were performed on ZTC with and without loading mechanical force, by using CO2, CH4, and H2, as adsorbates. Upon the contraction by loading 69 or 135 MPa, CO2 adsorption amount is increased, due to the deepening of the physisorption potential well inside the micropores, as proved by the increase of the heat of adsorption. Moreover, the adsorption amount is completely restored to the original one after releasing the mechanical force, indicating the fully reversible contraction/recovery of the ZTC framework against mechanical force. The experimental results are theoretically supported by a simulation using Grand Canonical Monte Carlo method. The similar adsorption enhancement is observed also on CH4, whereas H2 is found as an exception due to the weak interaction potential. 相似文献
970.
Prof. Dr. Masakazu Iwamoto Shouta Mizuno Prof. Dr. Masashi Tanaka 《Chemistry (Weinheim an der Bergstrasse, Germany)》2013,19(22):7214-7220
Propene, one of key building blocks for manufacturing plastics and chemicals, could be directly and stably produced from ethanol in good yields. The conversion degree of ethanol to propene reached approximately 60 mol % by using a 3 atom % scandium‐loaded indium oxide catalyst at 823 K in the presence of water and hydrogen. The introduction of Sc prevented the reduction of In2O3 to In metal during the reaction, and that of water decreased the coke formation. Both additions resulted in longer lifetimes of the catalysts. The hydrogen addition increased the conversion of acetone to propene. The reaction pathways are also suggested on the basis of the product distributions and the pulse experiments, ethanol→acetaldehyde→acetone→propene, which is quite different from the shape‐selective catalysis on zeolites and the dimerization‐metathesis of ethene on nickel ion‐loaded silica catalysts. 相似文献