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81.
Ayako Yano Nobuyuki Akai Hiroshi Ishii Chikahiro Satoh Takayuki Hironiwa Keith R. Millington Munetaka Nakata 《Polymer Degradation and Stability》2013
Thermal oxidative degradation of additive-free polypropylene pellets heated isothermally in dry air at 150 and 180 °C (below and above the melting point of 163 °C) was investigated by multichannel Fourier-transform chemiluminescence spectroscopy. The initial peak wavelength of chemiluminescence emission at 490 nm remained constant during the early stages of thermal degradation, but new emissions developed with time in the red spectral region over an extended oxidation period. The time-dependent luminescence spectra were deconvoluted into three emission bands by least-squares fitting using Gaussian curves. We concluded that at least three groups of luminescent species (luminophores), having different conjugation lengths, were generated by thermal oxidation over extended periods and show luminescence around 490, 660, and 740 nm. 相似文献
82.
Akira Kawashima Prof. Dr. Takayuki Nakanishi Prof. Dr. Tamaki Shibayama Prof. Dr. Seiichi Watanabe Prof. Dr. Koji Fujita Prof. Dr. Katsuhisa Tanaka Prof. Dr. Hitoshi Koizumi Prof. Dr. Koji Fushimi Prof. Dr. Yasuchika Hasegawa 《Chemistry (Weinheim an der Bergstrasse, Germany)》2013,19(43):14438-14445
Remarkable magneto‐optical properties of a new isolator material, that is, europium sulfide nanocrystals with gold (EuS–Au nanosystem), has been demonstrated for a future photo‐information technology. Attachment of gold particles that exhibit surface plasmon resonance leads to amplification of the magneto‐optical properties of the EuS nanocrystals. To construct the EuS–Au nanosystems, cubic EuS and spherical Au nanocrystals have been joined by a variety of organic linkers, that is, 1,2‐ethanedithiol (EDT), 1,6‐hexanedithiol (HDT), 1,10‐decanedithiol (DDT), 1,4‐bisethanethionaphthalene (NpEDT), or 1,4‐bisdecanethionaphthalene (NpDDT) . Formation of these systems was observed by XRD, TEM, and absorption spectra measurements. The magneto‐optical properties of the EuS–Au nanosystem have been characterized by using Faraday rotation spectroscopy. The Faraday rotation angle of the EuS–Au nanosystem is dependent on the Au particle size and interparticle distance between EuS and Au nanocrystals. Enhancement of the Faraday rotation of EuS–Au nanosystems was observed. The spin configuration in the excited state of the EuS–Au nanosystem was also investigated using photo‐assisted electron paramagnetic resonance. 相似文献
83.
84.
Copper‐Catalyzed CH Bond Direct Chalcogenation of Aromatic Compounds Leading to Diaryl Sulfides,Selenides, and Diselenides by Using Elemental Sulfur and Selenium as Chalcogen Sources Under Oxidative Conditions
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Prof. Fumitoshi Shibahara Takafumi Kanai Eiji Yamaguchi Akika Kamei Takayuki Yamauchi Prof. Toshiaki Murai 《化学:亚洲杂志》2014,9(1):237-244
The reactions of aromatic compounds and elemental chalcogens catalyzed by a copper salt with molecular oxygen as an oxidant were carried out. The reaction of 3‐substituted imidazo[1,5‐a]pyridines and elemental sulfur in the presence of CuTC (copper(I) thiophenecarboxylate) gave the corresponding bisimidazopyridyl sulfides in good to quantitative yields. The reaction proceeded even under aerobic oxidation conditions. The use of a polar solvent was crucial for the reaction, and DMSO (dimethyl sulfoxide) in particular stimulated the reaction. The reaction could be applied to common aromatic compounds, such as N‐methyl indole and dialkyl anilines. The reaction of indole proceeded at the nucleophilic C3 position rather than at the acidic C2 position. In addition, the reaction of dialkyl anilines proceeded with an ortho, para orientation. The reactions of imidazopyridines and elemental selenium under similar conditions gave the corresponding bisimidazopyridyl diselenides along with bisimidazopyridyl monoselenides. The resulting diselenides were readily converted to the corresponding monoselenides with unreacted imidazopyridines under the same conditions. The reaction could be applied to the copolymerization of bifunctional bisimidazopyridines and elemental sulfur to give oligomeric copolymers in quantitative yield. 相似文献
85.
Facile Insertion of Carbon Dioxide into Cu2(μ‐H) Dinuclear Units Supported by Tetraphosphine Ligands
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Kanako Nakamae Dr. Bunsho Kure Prof. Takayuki Nakajima Prof. Yasuyuki Ura Prof. Tomoaki Tanase 《化学:亚洲杂志》2014,9(11):3106-3110
Reactions of meso‐bis[(diphenylphosphinomethyl)phenylphosphino]methane (dpmppm) with CuI species in the presence of NaBH4 afforded di‐ and tetranuclear copper hydride complexes, [Cu2(μ‐H)(μ‐dpmppm)2]X ( 1 ) and [Cu4(μ‐H)2(μ4‐H)(μ‐dpmppm)2]X ( 2 ) (X=BF4, PF6). Complex 1 undergoes facile insertion of CO2 (1 atm) at room temperature, leading to a formate‐bridged dicopper complex [Cu2(μ‐HCOO)(dpmppm)2]X ( 3 ). The experimental and DFT theoretical studies clearly demonstrate that CO2 insertion into the Cu2(μ‐H) unit occurred with the flexible dicopper platform. Complex 2 also undergoes CO2 insertion to give a formate‐bridged complex, [Cu4(μ‐HCOO)3(dpmppm)2]X, during which the square Cu4 framework opened up to a linear tetranuclear chain. 相似文献
86.
Naokazu Kano Hideaki Miyake Keishi Sasaki Takayuki Kawashima 《Heteroatom Chemistry》2015,26(2):183-186
The Si Si bond of a pentacoordinated disilicate was readily cleaved by treatment with 2,3‐dichloro‐5,6‐dicyano‐p‐benzoquinone in the presence of sodium carbonate under mild conditions. The bond cleavage did not proceed under the same conditions after conversion of the disilicate into the corresponding monoanionic silylsilicate and neutral disilane by protonation. The difference in the charges of the Si Si bond compounds affects the reactivity toward an oxidant, resulting in the Si Si bond cleavage, considering that all of these compounds have a bond between pentacoordinated silicon atoms. 相似文献
87.
Takayuki Suzuki Tomohiko Kitsukawa Yasushi Hirata Satomi Tanaka Naoya Iwasaki 《先进技术聚合物》2014,25(1):123-129
The copolymer of hydroxypropyl methacrylate (HPMA) and photochromic spiropyran methacrylate (SPMA) has been synthesized. The films of the copolymer (P(HPMA‐SPMA)) in a hydrated state showed reversible swelling–shrinking behavior in response to photoreversible isomerization and metal complexation of SPMA units in spite of covalently noncross‐linked copolymers. In addition, the protonated open form of the SPMA units of the copolymer was possibly stabilized thermodynamically by the HPMA units from ultraviolet–visible absorption measurement of the hydrated P(HPMA‐SPMA) film. On the other hand, the difference in color of the hydrated films between P(HPMA‐AABMA) and P(NIPMA‐AABMA), which was a copolymer of N‐isopropyl methacryl amide (NIPMA) and azobenzene methacrylate (AABMA) as a pH indicator, was suggestive of the interference of the proximal hydroxyl groups of the immobilized HPMA units with protonation of the AABMA units. The HPMA units of the copolymers also contributed to improvement of thermodynamic stability of the metal complexes with the SPMA units. Copyright © 2013 John Wiley & Sons, Ltd. 相似文献
88.
Rhodium(I)‐Catalyzed Cyclization of Allenynes with a Carbonyl Group through Unusual Insertion of a CO Bond into a Rhodacycle Intermediate
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Dr. Yoshihiro Oonishi Takayuki Yokoe Akihito Hosotani Prof. Dr. Yoshihiro Sato 《Angewandte Chemie (International ed. in English)》2014,53(4):1135-1139
Rhodium(I)‐catalyzed cyclization of allenynes with a tethered carbonyl group was investigated. An unusual insertion of a C?O bond into the C(sp2)–rhodium bond of a rhodacycle intermediate occurs via a highly strained transition state. Direct reductive elimination from the obtained rhodacyle intermediate proceeds to give a tricyclic product containing an 8‐oxabicyclo[3.2.1]octane skeleton, while β‐hydride elimination from the same intermediate gives products that contain fused five‐ and seven‐membered rings in high yields. 相似文献
89.
90.
Toru Doi Akira Akimoto Akikazu Matsumoto Takayuki Otsu 《Journal of polymer science. Part A, Polymer chemistry》1996,34(3):367-373
Radical copolymerization of N-methylmaleimide (MeMI) as well as other N-alkylmaleimides (RMI) and isobutene (IB) was carried out with 2,2′-azobis(isobutyronitrile) as an initiator at 60°C. The initial rate of the copolymerization (Rp) was dependent on the monomer composition and was maximum at the 40 mol % of MeMI in the feed. A solvent effect on the Rp and the monomer reactivity ratio was observed in this copolymerization system, i.e., copolymerization in chloroform produced a higher Rp and an alternating tendency compared with those in dioxane (rMeMI = 0.14, r1B = 0 in chloroform and rMeMI = 0.47, r1B = 0 in dioxane). The alternating copolymer of RMI and IB shows a high glass transition temperature (Tg) and excellent thermal stability, e.g., the Tg and the thermal decomposition temperature (Td) were 152 and 363°C, respectively, for the alternating copolymer of MeMI and IB. Both the Tg and Td increased as the concentration of the MeMI unit in the copolymers increased. Colorless transparent sheets were obtained from press molding the alternating copolymers. They showed excellent mechanical and optical properties. © 1996 John Wiley & Sons, Inc. 相似文献