排序方式: 共有64条查询结果,搜索用时 14 毫秒
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Myunghee Kim Jitsuo Ohta Atsushi Kobayashi Hiroshi Fujioka Masaharu Oshima 《固体物理学:研究快报》2008,2(1):13-15
AlN films have been grown on atomically flat carbon face 6H‐SiC (000 ) substrates by pulsed laser deposition and their structural properties have been investigated. In‐situ reflection high‐energy electron diffraction observations have revealed that growth of AlN at 710 °C proceeds in a Stranski–Krastanov mode, while typical layer‐by‐layer growth occurs at room temperature (RT) with atomically flat surfaces. It has been revealed that the crystalline quality of the AlN film is dramatically improved by the reduction in growth temperature down to RT and the full width at half maximum values in the X‐ray rocking curves for 0004 and 10 2 diffractions of the RT‐grown AlN film are 0.05° and 0.07°, respectively. X‐ray reciprocal space mapping has revealed that the introduction of misfit dislocations is suppressed in the case of RT growth, which is probably responsible for the improvement in crystalline quality. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
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Synthesis and Characterization of Heterobimetallic Tantalum–Rhodium and Tantalum–Iridium Complexes Connected by a Tantalacyclopentadiene Fragment
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Keishi Yamamoto Kosuke Higashida Haruki Nagae Hayato Tsurugi Kazushi Mashima 《Helvetica chimica acta》2016,99(11):848-858
We report the synthesis of heterobimetallic Ta–Rh and Ta–Ir complexes bridged by a 2,5‐di‐tert‐butyltantalacyclopentadiene fragment. A mononuclear 2,5‐di‐tert‐butyltantalacyclopentadiene complex 2 was prepared by the reaction of (η2‐Me3SiC≡CSiMe3)TaCl3(dme) ( 1 ) with excess amounts of 3,3‐dimethylbut‐1‐yne in the presence of AlCl3. The tantalacyclopentadiene moiety of complex 2 served as a η4‐diene unit for coordinating the Rh and Ir centers; treatment of 2 with [M(μ‐Cl)(cod)]2 (M = Rh and Ir; cod = cycloocta‐1,5‐diene) in toluene gave TaRh(μ‐C4H2tBu2)Cl4(cod) ( 3 ) and [TaIr(μ‐C4H2tBu2)Cl4]2 ( 5 ), respectively. The X‐Ray diffraction study of 3 revealed a dative bond from an electron‐rich Rh toward an electron‐deficient Ta. Upon dissolving 3 in THF, [(thf)TaRh(μ‐C4H2tBu2)Cl3]2(μ‐Cl)2 ( 4 ) was isolated together with free cycloocta‐1,5‐diene. When complex 5 was treated with 1,2‐bis‐(diphenylphosphino)ethane (dppe), a monomeric Ta–Ir complex, TaIr(μ‐C4H2tBu2)Cl4(dppe) ( 6 ), was isolated. Ta–Rh and Ta–Ir heterobimetallic complexes 3 and 6 were reduced by a two‐electron process upon reaction with 2,3,5,6‐tetramethyl‐1,4‐bis(trimethylsilyl)‐1,4‐dihydropyrazine ( 7a : Si‐Me4‐DHP) or 2,5‐dimethyl‐1,4‐bis(trimethylsilyl)‐1,4‐dihydropyrazine ( 7b : Si‐Me2‐DHP) to afford the corresponding complexes TaM(μ‐C4H2tBu2)Cl2(L) ( 8 : M = Rh, L = cod; 9 : M = Ir, L = dppe), where the metallacycle moiety was assigned to have a tantalacyclopentadiene fragment with a large contribution of a tantalacyclopentatriene canonical form. 相似文献
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Tamon Okano Teruyuki Kobayashi Hisatoshi Konishi Jitsuo Kiji 《Tetrahedron letters》1982,23(47):4967-4968
The addition of formaldehyde to olefins is efficiently catalyzed by RhH2(O2COH)[P(i-Pr)3]2 and gives the corresponding aldehydes in neutral solution. 相似文献
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Lanthanide Complexes Supported by a Trizinc Crown Ether as Catalysts for Alternating Copolymerization of Epoxide and CO2: Telomerization Controlled by Carboxylate Anions
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Dr. Haruki Nagae Ryota Aoki Shin‐nosuke Akutagawa Julian Kleemann Risa Tagawa Tobias Schindler Dr. Gyeongshin Choi Dr. Thomas P. Spaniol Prof. Dr. Hayato Tsurugi Prof. Dr. Jun Okuda Prof. Dr. Kazushi Mashima 《Angewandte Chemie (International ed. in English)》2018,57(9):2492-2496
A new family of heterometallic catalysts based on trimetalated macrocyclic tris(salen) ligands and rare‐earth metals was prepared and structurally characterized. The LaZn3 system containing anionic ligands such as acetate plays a critical role in catalyzing the alternating copolymerization of cyclohexene oxide (CHO) and CO2 with a high proportion of carbonate linkages. Among the lanthanide metals, the CeZn3 system exhibits high catalytic activity with a turnover frequency (TOF) of over 370 h?1. NMR analysis of the complex and end‐group analysis of the polymer suggest that the acetate ligands are rapidly exchanged, not only among coordinated acetates, but also between coordinated acetates and added carboxylate anions. These unique properties make this the first example of telomerization for the copolymerization of CHO and CO2. 相似文献
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Promotion of photodynamic therapy-induced apoptosis by the mitochondrial protein Smac/DIABLO: dependence on Bax 总被引:11,自引:0,他引:11
Usuda J Chiu SM Azizuddin K Xue LY Lam M Nieminen AL Oleinick NL 《Photochemistry and photobiology》2002,76(2):217-223
Photodynamic therapy (PDT) using the second-generation photosensitizer phthalocyanine (Pc) 4 causes mitochondrial damage and induces apoptosis through the release of cytochrome c to the cytosol. Another protein of the mitochondrial intermembrane space, Smac/DIABLO (second mitochondria-derived activator of caspase/direct inhibitor of apoptosis-binding protein with low pI), is also released to the cytosol in response to apoptotic stimuli and promotes caspase activation by binding IAP. To investigate the possible role of Smac/DIABLO in apoptosis induced by Pc 4-PDT, we transfected Smac/DIABLO (tagged at its C-terminus with green fluorescent protein [GFP]) into MCF-7c3 cells (human breast cancer MCF-7 cells stably transfected with procaspase-3) and DU-145 cells (human prostate cancer cells that express no Bax because of a frameshift insertion mutation). Confocal microscopy showed that recombinant Smac/DIABLO, like cytochrome c, localized to mitochondria and colocalized with MitoTracker Red. Three hours after exposure of MCF-7c3 cells to PDT (200 nM Pc 4 and 150 mJ/cm2 red light), Smac/DIABLO-GFP, as well as cytochrome c, was found largely in the cytosol. In contrast, for DU-145 cells, both Smac/DIABLO-GFP and cytochrome c remained in the mitochondria after PDT. By staining with Hoechst 33,342, typical apoptotic nuclei were observed in MCF-7c3 cells, but not in DU-145 cells, after Pc 4-PDT. These results suggest that the release of Smac/DIABLO from mitochondria may be regulated by a Bax-mediated mechanism and that Smac/DIABLO may cooperate with the cytochrome c-dependent apoptosis pathway. In addition, in MCF-7c3 cells transfected by Smac/DIABLO-GFP, apoptosis induced by Pc 4-PDT was greater than in cells transfected with the GFP vector alone or in untransfected cells, as determined by flow cytometry. Thus, Smac/DIABLO promotes apoptosis after Pc 4-PDT in a Bax-dependent manner and may facilitate the passage of PDT-treated cells through the late steps of apoptosis. 相似文献
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3-thiophene- and 3-furancarboxylic acids efficiently undergo perarylation accompanied by cleavage of the three C-H bonds and decarboxylation upon treatment with excess aryl bromides in the presence of a palladium catalyst to give the corresponding tetraarylated products in good yields. 相似文献
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Darryl F. Nater Christoph J. Kaul Lukas Lätsch Hayato Tsurugi Kazushi Mashima Christophe Copéret 《Chemistry (Weinheim an der Bergstrasse, Germany)》2022,28(22):e202200559
Tailored molybdenum(VI)-oxo complexes of the form MoOCl2(OR)2(OEt2) catalyse olefin metathesis upon reaction with an organosilicon reducing agent at 70 °C, in the presence of olefins. While this reactivity parallels what has recently been observed for the corresponding classical heterogeneous catalysts based on supported metal oxide under similar conditions, the well-defined nature of our starting molecular systems allows us to understand the influence of structural, spectroscopic and electronic characteristics of the catalytic precursor on the initiation and catalytic proficiency of the final species. The catalytic performances of the pre-catalysts are determined by the highly electron withdrawing (σ-donation) character of alkoxide ligands, OtBuF9 being the best. This activity correlates with both the 95Mo chemical shift and the reduction potential that follows the same trend: OtBuF9>OtBuF6>OtBuF3. 相似文献