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121.
Shigeru Sasaki 《Journal of organometallic chemistry》2011,696(21):3307-3315
The sterically crowded triarylphosphines bearing formyl and benzoyl groups were synthesized and characterized by X-ray crystallography. The benzoyl derivative was converted to the p-quinomethane conjugated with the triarylphosphine. The McMurry coupling of the formyl derivative afforded the diarylethene bearing the two sterically-crowded-triarylphosphine moieties. The cyclic voltammograms of these compounds show reversible redox waves corresponding to the oxidation to the radical cations of the triarylphosphines and irreversible or quasi-reversible waves corresponding to the reduction of the acceptor moieties. The electronic and the fluorescence spectra of these π-conjugated systems, especially push-pull substituted derivatives, exhibit bathochromic shift typical of the extended π-conjugated systems especially in the polar solvent, and the large Stokes shift typical of the crowded triarylphosphines is enhanced by conjugation with the acceptor moiety. 相似文献
122.
Shin‐Ichi Yusa Shigeki Awa Masanori Ito Takeshi Kawase Tadao Takada Kenichi Nakashima Dian Liu Shigeru Yamago Yotaro Morishima 《Journal of polymer science. Part A, Polymer chemistry》2011,49(13):2761-2770
Water‐soluble diblock copolymer, poly(N‐isopropylacrylamide)‐block‐poly(N‐vinyl‐2‐pyrroridone) (PNIPAMm‐b‐PNVPn), was found to associate with fullerene (C60), and thus C60 can be solubilized in water. The 63C60/PNIPAMm‐b‐PNVPn micelle formed a core‐shell micelle‐like aggregate comprising a C60/PNVP hydrophobic core and a thermoresponsive PNIPAM shell. The C60‐containing polymer micelle formation and its thermoresponsive behavior were characterized using light scattering and 1H NMR techniques. The hydrodynamic radius (Rh) of the C60‐bound polymer micelle increased with increasing temperature, which was ascribed to the hydrophobic association between dehydrated PNIPAM shells above lower critical solution temperature (LCST). 1H NMR data suggest that the motion of the PNIPAM block is restricted above LCST due to the dehydration of the PNIPAM shell in water. The generation of singlet oxygen by photosensitization by the C60‐bound polymer micelle was confirmed from photooxidation of 9,10‐anthracenedipropionic acid. Furthermore, DNA was found to be cleaved by visible light irradiation in the presence of the C60‐bound polymer micelle. Therefore, there may be a hope for a pharmaceutical application of the C60‐bound polymer micelle to cancer photodynamic therapy. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011. 相似文献
123.
124.
Shigeru Ohba Makoto Eishima 《Acta Crystallographica. Section C, Structural Chemistry》2000,56(12):e557-e558
In the title compound, trans‐[CoCl(NO2)(C2H8N2)2]NO3, a distorted octahedral CoIII complex shows an orientational disorder such that the positions of the nitro and chloro ligands are exchanged. The occupation factors of the major and minor orientations are 84 and 16%, respectively. The O atoms of the nitrate ion are disordered over two sites. 相似文献
125.
Nabajyoti Saikia Shigeru Kato Toshinori Kojima 《Journal of Thermal Analysis and Calorimetry》2012,109(1):273-286
Tricalcium aluminate (Ca3Al2O6, C3A) containing 0?C5% of Sn was synthesized by solid-state method, and the products were characterized by XRD technique. Differential thermo-analytical technique (DTA) along with X-ray diffraction (XRD) analysis and scanning electron microscopy (SEM) were applied to study the hydration behaviour of different C3A samples with and without the presence of gypsum. Results indicate that C3A can accommodate small amount of Sn in its structure and remaining amount forms SnO2. Hydration studies of the synthesized C3A shows that the additions of 0.5 and 1% Sn increase and 2% Sn decrease the reactivity of C3A at the initial period (<3?h) of hydration. Increasing additions of Sn also increase the amounts of amorphous phases and hexagonal calcium aluminate hydrates in the cement pastes. The stabilities of these hydration products also increase with increasing content of Sn in C3A at the experimental conditions. The presence of Sn significantly changes the hydration of C3A and gypsum solid mixture at the initial period of hydration by enhancing the formation of more amounts of AFt and AFm phases. However, at the later stage of hydration (on or after 3?days), the hydration products in C3A and gypsum pastes with and without the presence of Sn are almost similar. 相似文献
126.
We consider a convex polygonal heat conductor whose inscribed circle touches every side of the conductor. Initially, the conductor
has constant temperature and, at every time, the temperature of its boundary is kept at zero. The hot spot is the point at
which temperature attains its maximum at each given time. It is proved that, if the hot spot is stationary, then the conductor
must satisfy two geometric conditions. In particular, we prove that these geometric conditions yield some symmetries provided
the conductor is either pentagonal or hexagonal.
This research was partially supported by Grants-in-Aid for Scientific Research (B) (# 12440042) and (B) (# 15340047) of Japan
Society for the Promotion of Science, and by a Grant of the Italian MURST. 相似文献
127.
128.
Background
BIR family proteins are evolutionarily conserved anti-apoptotic molecules. One member of Xenopus BIR family proteins, xEIAP/XLX, is a weak apoptosis inhibitor and rapidly degraded in a cell-free apoptotic execution system derived from interphase egg extracts. However, unfertilized eggs are naturally arrested at the metaphase of meiosis II by the concerted activities of Mos-MEK-p42MAPK-p90Rsk kinase cascade (cytostatic factor pathway) and many mitotic kinases. Previous studies suggest that cytostatic factor-arrested egg extracts are more resistant to spontaneous apoptosis than interphase egg extracts in a p42MAPK-dependent manner. We tested whether xEIAP/XLX might be phosphorylated in cytostatic factor-arrested egg extracts, and also examined whether xEIAP/XLX could be functionally regulated by phosphorylation. 相似文献129.
Harada T Ikeda S Hashimoto F Sakata T Ikeue K Torimoto T Matsumura M 《Langmuir : the ACS journal of surfaces and colloids》2010,26(22):17720-17725
A core-shell composite consisting of a palladium (Pd) nanoparticle and a hollow carbon shell (Pd@hmC) was employed as a catalyst for aerobic oxidation of various alcohols. The core-shell structure was synthesized by consecutive coatings of Pd nanoparticles with siliceous and carbon layers followed by removal of the intermediate siliceous layer. Structural characterizations using TEM and N(2) adsorption-desorption measurements revealed that Pd@hmC thus-obtained was composed of a Pd nanoparticle core of 3-6 nm in diameter and a hollow carbon shell with well-developed mesopore (ca. 2.5 nm in diameter) and micropore (ca. 0.4-0.8 nm in diameter) systems. When compared to some Pd-supported carbons, Pd@hmC showed a high level of catalytic activity for oxidation of benzyl alcohol into benzaldehyde using atmospheric pressure of O(2) as an oxidant. The Pd@hmC composite also exhibited a high level of catalytic activity for aerobic oxidations of other primary benzylic and allylic alcohols into corresponding aldehydes. The presence of a well-developed pore system in the lateral carbon shell enabled efficient diffusion of both substrates and products to reach the central Pd nanoparticles, leading to such high catalytic activities. This core-shell structure also provided high thermal stability of Pd nanoparticles toward coalescence and/or aggregation due to the physical isolation of each Pd nanoparticle from neighboring particles by the carbon shell: this specific property of Pd@hmC resulted in possible regeneration of catalytic activity for these aerobic oxidations by a high-temperature heat treatment of the sample recovered after catalytic reactions. 相似文献
130.
Hidetaka Tsujimoto Hotaka Asuka Shigeru Ikawa Hiroyuki Nakazumi 《Journal of organometallic chemistry》2010,695(17):1972-10838
In order to develop highly emissive red phosphorescent materials for OLED application, novel bis-cyclometalated iridium(III) complexes were developed using the 1-(dibenzo[b,d]furan-4-yl)isoquinolinato-N,C3′ (dbfiq) cyclometalating ligand. When 1,3-bis(3,4-dibutoxyphenyl)propane-1,3-dionate (bdbp) is employed as an ancillary ligand, Ir(dbfiq)2(bdbp) 1 exhibits red photoluminescence (PL) at 640 nm with a quantum yield (ΦPL) of 0.61 (in toluene, 298 K). Replacement of bdbp to dipivaloylmethanate (dpm) and acetylacetonate (acac) (Ir(dbfiq)2(dpm) 2 and Ir(dbfiq)2(acac) 3, respectively) does not affect the PL spectrum, but reduces ΦPL to 0.55 and 0.49 for 2 and 3, respectively. Similar tendency is also found in the doped poly(methyl methacrylate) (PMMA) film, and 1 is more emissive (ΦPL = 0.17) than 2 and 3 (ΦPL = 0.08 and 0.06, respectively). Using 1 as a phosphorescent dopant, polymer light-emitting diodes (PLEDs) were fabricated, of which structure was ITO/PEDOT:PSS (40 nm)/PVCz:1:PBD (100 nm)/CsF (1 nm)/Al (250 nm). Pure red electroluminescence (EL) is obtained from the fabricated PLEDs, affording a CIE chromaticity coordinate of (0.68, 0.31). When 0.51 mol% of 1 is incorporated in the PVCz-based emitting layer, the PLED shows maximum luminance of 7270 cd m−2 at 16.5 V, power efficiency of 1.4 lm W−1 at 7.5 V, and external quantum efficiency of 6.4% at 9.0 V. PLEDs with the same structure and components were also fabricated using 2 and 3, and their device characteristics were investigated. In proportion to the PL quantum yields, 1 affords better device performance than 2 and 3. Owing to four butoxy groups introduced to the bdbp ligand, 1 exhibits high solubility in organic solvents such as chloroform and toluene, and thus, is an excellent red phosphorescent dopant for solution-processed OLEDs. 相似文献