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排序方式: 共有454条查询结果,搜索用时 15 毫秒
91.
Hayashi Y Obata N Tamaru M Yamaguchi S Matsuo Y Saeki A Seki S Kureishi Y Saito S Yamaguchi S Shinokubo H 《Organic letters》2012,14(3):866-869
A biphenyl-fused BODIPY was synthesized through a facile oxidative cyclization of peripheral aryl-substituents at the β-position of the BODIPY unit. The extended π-system of the fused BODIPY induces near-infrared (NIR) absorption and strong π-π interactions in the solid state. These features are beneficial for the application of the dye as a functional material. The biphenyl-fused BODIPY dye was demonstrated to exhibit photocurrent conversion ability on the basis of its n-type semiconducting property. 相似文献
92.
Subclinical mastitis is a common infectious disease affecting dairy cows. To develop an early diagnostic device for this disease, we focused on measuring an increase in the number of neutrophils in raw milk of mastitic cows. Superoxide anions (O(2)(-)), secreted by neutrophils, can be a good indicator of neutrophil concentration, and therefore, the seriousness of the mastitis. In this study, neutrophils in raw milk samples were separated from fat globules in a flow channel using differences in specific gravity and specific adhesion of neutrophils to P-selectin. Neutrophils trapped in the flow channel were subsequently concentrated in an array of micropillars of a working electrode modified with P-selectin and superoxide dismutase. The O(2)(-) secreted from the trapped neutrophils was electrochemically detected. A difference in the detection current was observed between normal and mastitic milk samples. A clear linear relationship between the electric current and cell density was observed. 相似文献
93.
Yousuke Ooyama Naoya Yamaguchi Shogo Inoue Tomoya Nagano Eigo Miyazaki Hiroshi Fukuoka Ichiro Imae Kenji Komaguchi Joji Ohshita Yutaka Harima 《Tetrahedron》2012,68(2):529-533
We have newly designed and synthesized unsymmetrical carbazole-type D–π–A fluorescent dyes. The dyes show a bathochromic shift-type mechanofluorochromism (MFC): grinding of as-recrystallized dyes induces a bathochromic shift of fluorescent color and the fluorescent color is recovered by heating or exposure to solvent vapor. In order to clarify the MFC mechanism for the carbazole-type D–π–A fluorescent dyes, time-resolved fluorescence spectroscopy, X-ray powder diffractometry, single-crystal X-ray structural analysis, IR spectroscopy, and differential scanning calorimetry are performed before and after grinding of the solids. On the basis of experimental results and semi-empirical molecular orbital calculations (AM1 and INDO/S), we have revealed that the MFC is attributed to a reversible switching between crystalline and amorphous states with changes of intermolecular hydrogen bonding and π–π interaction. 相似文献
94.
Polysiloxanes are useful materials because of their functionality, such as high thermal stability, electrical resistance, and hydrophobicity. In this regard, we studied palladium-catalyzed formation of iodo- and bromopolysiloxanes from two types of hydrosiloxanes, α,ω-dihydropoly(dimethylsiloxane) (1) and cyclotetra(hydromethylsiloxane) (2), and their reactions. Treatment of 1 with mixtures of cyclic ethers or lactones and MeI or allylBr in the presence of a catalytic amount of PdCl2 gave the corresponding α,ω-bis(haloalkoxy and haloalkanoyloxy)poly(dimethylsiloxane)s in good yields, via iodo- and bromopoly(dimethylsiloxane) intermediates. Transformation of the iodobutoxy-terminal units in the resulting poly(dimethylsiloxane) into aminoalkoxy groups was examined. The formation of α,ω-diiodo- and dibromopoly(dimethylsiloxane)s from 1 was confirmed by spectrometric analysis as well as by quenching experiments with ethanol. A reaction of α,ω-dibromopoly(dimethylsiloxane) with 2,5-dilithiothiophene gave a polydimethylsiloxane-thiophene alternating polymer. Similar palladium-catalyzed reactions of 2 with THF/MeI, THF/allylBr, and δ-valerolactone/allylBr afforded cyclo-(halobutoxy- and bromobutanoyloxymethylsiloxane)s in moderate yields. This would provide a new strategy for the introduction of various substituents to the terminal positions of linear polysiloxane and to the cyclosiloxane core. 相似文献
95.
Planar-chiral palladium complexes {[[N,N'-[1,4-butanediylbis(oxy-7,1-naphthalenediyl)]bis(2-pyridinecarboxamidato)](2-)-κN(1),κN(1)',κN(2),κN(2)']palladium (PdL(4)) and [[2,2'-[1,4-butanediylbis[[(oxy-7,1-naphthalenediyl)imino]methyl]]dipyrrolato](2-)-κN(1),κN(1)',κN(2),κN(2)']palladium (PdL(5))} were synthesized from achiral tetradentate ligands N,N'-[1,4-butanediylbis(oxy-7,1-naphthalenediyl)]bis(2-pyridinecarboxamide) (H(2)L(4)) and N,N'-bis[(1H-pyrrol-2-yl)methylidene]-7,7'-(1,4-butanediyldioxy)bis(1-naphthalenamine) (H(2)L(5)) bearing two dissymmetric bidentate units at both ends and a Pd(II) ion, respectively. The palladium complexes were crystallized in the monoclinic space group P2(1)/n with the unit cell parameters a = 16.5464(6) ?, b = 11.3534(4) ?, c = 17.6697(7) ?, β = 115.5300(10)°, and Z = 4 for PdL(4) and a = 17.2271(8) ?, b = 10.1016(5) ?, c = 17.9361(9) ?, β = 105.6310(10)°, and Z = 4 for PdL(5). The planar-chiral structures of PdL(4) and PdL(5) were confirmed by single-crystal X-ray analyses, resulting in the fact that the crystals were racemic mixtures. The racemic mixtures were successfully resolved by using chiral high-performance liquid-chromatography techniques. Racemizations of the complexes were found to be drastically dependent on the arrangement of the charged or uncharged metal-binding N atoms of the ligands. 相似文献
96.
Dr. Shohei Yamashita Tatsuya Sudo Prof. Dr. Hidehiro Kamiya Prof. Dr. Yohei Okada 《Chemistry (Weinheim an der Bergstrasse, Germany)》2022,28(50):e202201560
Surface ligands are essential tools for the stabilization of colloidal nanoparticles (NPs) in solvents. However, knowledge regarding the effects of the ligand shell, especially the ligand length, is insufficient and controversial. Here we demonstrate solution-based experiments on n-alkylphosphonate-capped TiO2 NPs to investigate the effects of ligand length and solution temperature on colloidal stability. A robust ligand-exchange process is achieved that draws free ligands and impurities away from the colloidal solution. In the case of 8 nm anatase NPs in toluene, the dodecylphosphonate ligand provided better colloidal stability than all the other n-alkylphosphonate ligands. In addition, relaxation studies suggested there is kinetic hysteresis in the dispersion/agglomeration transition. The proposed method is applicable to a wide range of surface ligands designed to maximize the colloidal stability of NPs. 相似文献
97.
Shohei Makita Hiroto Kudo Tadatomi Nishikubo 《Journal of polymer science. Part A, Polymer chemistry》2004,42(15):3697-3707
Hyperbranched polyimides (HBPI)s with high glass‐transition temperatures and excellent thermal stability were synthesized through the reaction of commercially available carboxylic acid dianhydrides with tris[4‐(4‐aminophenoxy)phenyl]ethane (TAPE). In particular, hyperbranched polyimide HBPI(TAPE‐DSDA), prepared through the reaction of TAPE with 3,3′,4,4′‐diphenylsulfonetetracarboxylic dianhydride (DSDA), showed higher thermal stability and good solubility. Furthermore, alkaline‐developable, photosensitive HBPI(TAPE‐DSDA)‐MA‐CA was prepared through the reaction of HBPI(TAPE‐DSDA) with glycidyl methacrylate with tetrabutylammonium bromide as a catalyst in N‐methyl‐2‐pyrrolidinone (NMP) followed by the addition reaction of cis‐1,2,3,6‐tetrahydrophthalic anhydride with triphenylphosphine as a catalyst in NMP. The glass‐transition temperatures of HBPI(TAPE‐DSDA)‐MA‐CA were greater than 300 °C. A resist composed of 74 wt % HBPI(TAPE‐DSDA)‐MA‐CA, 22.2 wt % trimethylpropane triacrylate, and 3.8 wt % Irgacure 907 as a photoinitiator achieved a resolution of a 55‐μm line pattern and a 275‐μm space pattern by UV irradiation (1000 mJ/cm2). © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 3697–3707, 2004 相似文献
98.
Ohno H Hamaguchi H Ohata M Kosaka S Tanaka T 《Journal of the American Chemical Society》2004,126(28):8744-8754
We have developed a highly regio- and stereoselective synthesis of medium-sized heterocycles containing one or two heteroatoms via cyclization of bromoallenes bearing an oxygen, nitrogen, or carbon nucleophilic functionality in the presence of a palladium(0) catalyst and alcohol. In this reaction, bromoallenes act as an allyl dication equivalent, and the intramolecular nucleophilic attack takes place exclusively at the central carbon atom of the allene moiety. Interestingly, bromoallenes having a carbon nucleophile with a five-atom tether afford eight-membered rings with trans-configuration, while those having an oxygen or a nitrogen nucleophile give the corresponding cis-rings selectively. This is the first example that demonstrates the synthesis of medium-sized rings via cyclization of bromoallenes, and this reaction provides a very useful method for a catalytic synthesis of seven- and eight-membered heterocycles without using high dilution conditions. 相似文献
99.
Kunishima M Yamamoto K Watanabe Y Hioki K Tani S 《Chemical communications (Cambridge, England)》2005,(21):2698-2700
A novel immobilized dehydrocondensing reagent comprised of a triazine-type dehydrocondensing reagent itself in a polymerized form was synthesized by copolymerization between tetra(ethylene glycol) bis(dichlorotriazinyl) ether and tris(2-aminoethyl)amine. 相似文献
100.
Kiyoshi Shibata Hiroshi Kimura Akira Tsuchida Tsuneo Okubo Shohei Sato Kohji Yoshinaga 《Colloid and polymer science》2006,284(4):372-379
Electro-optic responses of colloidal crystals consist of poly(maleic anhydride-co-styrene)-modified silica spheres (P(MA-ST)/SiO2) in acetonitrile and the crystals immobilized with a gelator, N-benzyloxycarbonyl-L-isoleucilaminooctadecane (Z-L-Ile-C-18), are studied by reflected-light intensity measurements and time-resolved reflection spectroscopy. Application of
an alternating electric field deforms P(MA-ST)/SiO2 crystal lattices reversibly. The response waveforms from the crystals are dependent on the frequency and strength of the
applied electric field; similar dependencies have been qualitatively observed for the colloidal crystals consisting of polystyrene
or silica spheres in aqueous media in our previous studies. Both gelated and ungelated P(MA-ST)/SiO2 crystals change the reflection intensity, however, the amplitude is larger for the latter. The small response for the gelated
P(MA-ST)/SiO2 crystals is attributed to the higher elastic modulus (G). The G value of the gelated P(MA-ST)/SiO2 crystals in acetonitrile is estimated from the change in the inter-sphere distance to be 8.0 Pa, which is about 2.3 and 2.4
times larger than that for ungelated P(MA-ST)/SiO2 crystals in acetonitrile and colloidal silica crystals in aqueous media, respectively. 相似文献