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1.
Hayate Saito Keita Yamamoto Yosuke Sumiya Ling‐Jun Liu Keisuke Nogi Satoshi Maeda Hideki Yorimitsu 《化学:亚洲杂志》2020,15(16):2442-2446
C?H iodination of aromatic compounds has been accomplished with the aid of sulfinyl directing groups under palladium catalysis. The reaction proceeds selectively at the peri‐position of polycyclic aryl sulfoxides or at the ortho‐position of phenyl sulfoxides. The iodination products can be further converted via iterative catalytic cross‐coupling at the expense of the C?I and C?S bonds. Computational studies suggest that peri‐C?H palladation would proceed via a non‐directed pathway, wherein neither of the sulfur nor oxygen atom of the sulfinyl group coordinates to the palladium before and at the transition state. 相似文献
2.
Kenji Sumiya Tsunetaka Matsumoto Seiji Watatani Fumttada Hayama 《Journal of Physics and Chemistry of Solids》1979,40(12):1097-1102
Highly coercive magnetic powder was obtained by growing cobalt ferrite on the surface of γ-Fe2O3 particles in highly alkaline suspensions containing cobalt and ferrous ions in a Co/Fe molar ratio = . The mechanism of the growth and the structure of cobalt ferrite on γ-Fe2O3 were studied by X-ray diffraction and electron diffraction techniques. Results show that crystals of cobalt ferrite CoFe2O4 with a spinel type crystal structure of lattice constant 8.415 Å grew epitaxially on γ-Fe2O3. The acicular direction of the epitaxially grown Co-γ-Fe2O3 as well as γ-Fe2O3 was in the [01] direction. It was found that from the lattice constant value and the half width of X-ray diffraction peaks, the lattice constant epitaxially grown Co γ-Fe2O3 may be attributed to two kinds of crystals, viz., seed γ-Fe2O3 () which was partly reduced to Fe3O4, and surface layer CoFe2O4 (). The crystal growth in the interface between the seed crystals and the growth layer was affected by the crystal structure of the seed crystals. The lattice constant of CoFe2O4 which was located in the vicinity of the interface was almost equal to that of the seed crystals. 相似文献
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Yu Shibata Haruki Nagae Shiki Sumiya Rapha?l Rochat Hayato Tsurugi Kazushi Mashima 《Chemical science》2015,6(10):5394-5399
An alkylyttrium complex supported by an N,N′-bis(2,6-diisopropylphenyl)ethylenediamido ligand, (ArNCH2CH2NAr)Y(CH2SiMe3)(THF)2 (1, Ar = 2,6-iPr2C6H3), activated an ortho-phenyl C–H bond of 2-phenylpyridine (2a) to form a (2-pyridylphenyl)yttrium complex (3a) containing a five-membered metallacycle. Subsequently, a unique C(sp2)–C(sp2) coupling of 2-phenylpyridine proceeded through a bimetallic yttrium intermediate, derived from an intramolecular shift of the yttrium center to an ortho-position of the pyridine ring in 3a, to yield a bimetallic yttrium complex (4a) bridged by two-electron reduced 6,6′-diphenyl-2,2′-bipyridyl. Aryl substituents at the ortho-position of the pyridine ring were key in order to destabilize the μ,κ2-(C,N)-pyridyldiyttrium intermediate prior to the C(sp2)–C(sp2) bond formation. 相似文献
6.
It has been experimentally shown that an O(-c)-polar ZnO surface is more stable than a Zn(+c)-polar surface in H(2) ambient. We applied first-principles calculations to investigating the polarity dependence on the stability at the electronic level. The calculations revealed that the -c surface terminated with H atom was stable maintaining a wurtzite structure, whereas the +c surface was unstable due to the change of coordination numbers of Zn at the topmost surface from four (wurtzite) to six (rock salt). This causes the generation of O(2) molecules, resulting in instability at the +c surface. 相似文献
7.
D Yamamoto K Matsumoto T Ishida M Inoue S Sumiya K Kitamura 《Chemical & pharmaceutical bulletin》1989,37(10):2577-2581
In order to elucidate the conformational characteristics of cysteine protease inhibitors contributing to their inhibitory activities, the conformation of E-64 (N-[N-(L-3-trans-carboxyoxiran-2-carbonyl)-L-leucyl]-agmatine), a potent inhibitor of papain, was determined by X-ray crystal structure analysis. The molecules were packed in the crystal through electrostatic forces and hydrogen bonding between the oppositely charged terminal groups and between the amide groups. Two crystallographically independent E-64 molecules both took a flattened and slightly curved structure, which is similar to that of loxistatin, a related cysteine protease inhibitor. Based on the present results, a possible inhibitory mechanism of E-64 is proposed, with reference to the binding mode observed in the crystal structure of papain-substrate analogue complex. 相似文献
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Masatomo Sumiya Yutaro Kamo Masaki Takeguchi Hideki Yoshikawa Keisuke Kobayashi Minoru Hagino Shunro Fuke 《Applied Surface Science》2010,256(14):4442-4446
Photocathode devices operating in reflection-mode, where the photoemission is detected on the same side as the light irradiation, were developed for the detection of deep ultraviolet light by using p-AlxGa1−xN films grown on Si(1 1 1) substrates. The external quantum efficiencies were as high as 20-15% at 200 nm and 280 nm, while the value was as low as 10−2% at 310 nm. The on-off ratio was more than four orders of magnitude, which represents high solar-blind sensitivity. The escape probability of AlxGa1−xN photocathode was decreased with increase of AlN mole fraction. The effective barrier potential against the photoelectron emission near the surface was reduced due to the upward shift of conduction band of AlxGa1−xN. The photoemission from the AlxGa1−xN films terminated with Cs-O adatoms will be discussed in terms of band diagrams that were evaluated by hard X-ray photoelectron spectroscopy. 相似文献
10.
Oriented growth of large size calcium fluoride single crystals for optical lithography 总被引:2,自引:0,他引:2
We report (1 1 1), (1 1 0) and (1 0 0) growth of CaF2 by the vertical Bridgman method. Crystals up to 250 mm diameter were grown and various growth parameters such as growth rate, temperature gradient and post-growth cooling rate were studied. It was found that the growth rate and the cooling rate are slower for the larger diameter crystals with a fixed temperature gradient. These growth parameters were optimized for growing the crystals along specific orientation after realizing that CaF2 has a tendency to grow along an orientation close to 1 1 0. Degradation in optical transmittance was evaluated by irradiating the crystal to γ-rays up to a dose of 105 rad. Optimized scavenger addition resulted in crystals with better radiation resistance and excellent VUV transmittance. 相似文献