排序方式: 共有46条查询结果,搜索用时 15 毫秒
31.
Zheng-Hua Zhang Wen-Li Meng Taka-Aki Okamura Ling-Yan Kong Norikazu Ueyama 《Supramolecular chemistry》2013,25(4):317-325
Three metal-organic frameworks (MOFs) [La(bta)(H2O)]n (1), [La(bta)(H2O)2·H2O]n (2) and [Er(bta)(H2O)2·H2O]n (3) with different structures were synthesized by reactions of 1,3,5-benzenetriacetic acid (H3bta) with the corresponding lanthanide salts under different conditions. X-ray diffraction analyses reveal that complexes 1 and 2 have the same metal atom and ligand but different structures. In 1, each bta3 ? adopts cis, cis, cis conformation and acts as a μ6-bridge linking six lanthanum atoms to form a 2D framework; while in 2, the bta3 ? has cis, trans, trans conformation and serves as a μ5-bridging ligand, which results in a 3D channel-like structure. In the case of 3, each bta3 ? also adopts cis, trans, trans conformation but acts as a μ4-bridge linking four erbium atoms to form a 3D channel-like framework. The results imply that the reaction conditions have great impact on the structure of MOFs, and the flexible triacid ligand H3bta is versatile and can adopt different conformations in the formation of MOFs. The magnetic property of complex 3 was investigated in the temperature range of 1.8–300 K. 相似文献
32.
Ling Li Jian Fan Taka-Aki Okamura Yi-Zhi Li Norikazu Ueyama 《Supramolecular chemistry》2013,25(5):361-370
Assembly of three-connecting ligands 1,3,5-tris(1-imidazolyl)benzene (tib) and 1,3,5-tris(imidazol-1-ylmethyl)-2,4,6-trimethylbenzene (titmb) with cadmium(II) and silver(I) salts provide new metal-organic frameworks, [Cd(tib)2](NO3)2·4H2O (1), [Ag(tib)(PPh3)](CF3SO3) (2) and [Ag(titmb)(PPh3)](CF3SO3)·1.5H2O (3) (PPh3=triphenylphosphine). Single-crystal X-ray diffraction studies reveal that complexes 1 and 3 are two-dimensional honeycomb networks, while complex 2 is a noninterpenetrated three-dimensional architecture with (10,3)-a topology. The results indicate that the nature (structure and flexibility) of the organic ligands and the bulky auxiliary ligand have great impact on the assembly and structure of metal-organic frameworks. The photoluminescent properties of the synthesized complexes were studied in the solid state at room temperature. 相似文献
33.
Yutaka Aoki Atsuhiko Toyama Takashi Shimada Tetsuyoshi Sugita Chikage Aoki Yukari Umino Atsushi Suzuki Daisuke Aoki Yataro Daigo Yusuke Nakamura Taka-Aki Sato 《Proceedings of the Japan Academy. Series B, Physical and biological sciences》2007,83(7):205-214
Significant advances have been made in the past decade in the field of mass spectrometry imaging (MS imaging). It is a relatively unestablished technique aimed at direct, high-sensitive and spatially exclusive detection of biological molecules from the surface of tissue sections, so that semi-quantitative distribution map of the analyte can be reconstituted from the mass spectra obtained. There is tremendous potential in its application especially in clinical field, such as biomarker discovery or pharmacokinetic study. However, vast majority of the work has been performed on frozen tissue sections, while it remains generally unpractical to produce frozen sections with clinically resected tumor samples. Here we report our novel sample preparation technique that enabled MS imaging from formalin-fixed paraffin embedded (FFPE) tissue section, including retrospective archive as old as 11 years. FFPE sections were first dewaxed with pre-warmed xylene, and exposed tissue surface was enzymatically digested in nanoliter scale droplets to retain analyte localization. As a result, we succeeded in obtaining MS images of peptide peaks derived from several proteins, identified by MS/MS analysis, using ovarian cancer FFPE sections. The qualities of mass spectra obtained by this method were not significantly different from those obtained from frozen sections. By this, we opened the door to retrospective study of past clinical cases in aim to discover molecular biomarker. 相似文献
34.
S Akatsu Y Kanematsu TA Kurihara S Sueyoshi Y Arikawa M Onishi S Ishizaka N Kitamura Y Nakao S Sakaki K Umakoshi 《Inorganic chemistry》2012,51(15):7977-7992
Heteropolynuclear Pt(II) complexes with 3,5-diphenylpyrazolate [Pt(2)Ag(4)(μ-Cl)(2)(μ-Ph(2)pz)(6)] (3), [Pt(2)Ag(2)Cl(2)(μ-Ph(2)pz)(4)(Ph(2)pzH)(2)] (4), [Pt(2)Cu(2)Cl(2)(μ-Ph(2)pz)(4)(Ph(2)pzH)(2)] (5), [Pt(2)Ag(4)(μ-Cl)(μ-Me(2)pz)(μ-Ph(2)pz)(6)] (7), and [Pt(2)Ag(4)(μ-Me(2)pz)(2)(μ-Ph(2)pz)(6)] (8) have been prepared and structurally characterized. These complexes are luminescent except for 5 in the solid state at an ambient temperature with emissions of red-orange (3), orange (4), yellow-orange (7), and green (8) light, respectively. Systematic red shift of the emission energies with the number of chloride ligands was observed for 3, 7, and 8. DFT calculations indicate that the highest occupied molecular orbital (HOMO) as well as HOMO-1 of the heterohexanuclear complexes, 3, 7, and 8, having Pt(2)Ag(4) core, mainly consist of dδ orbital of Pt(II) and π orbitals of Ph(2)pz ligands, while the lowest unoccupied molecular orbital (LUMO) of these complexes mainly consists of in-phase combination of 6p of two Pt(II) centers and 5p of four Ag(I) centers. It is likely that the emissions of 3, 7, and 8 are attributed to emissive states derived from the Pt(2)(d)/π → Pt(2)Ag(4) transitions, the emission energy of which depends on the ratio of chloride ligands to pyrazolate ligands. 相似文献
35.
Y Tobu R Ikeda TA Nihei K Gotoh H Ishida T Asaji 《Physical chemistry chemical physics : PCCP》2012,14(35):12347-12354
The temperature dependence of (35)Cl NQR frequencies and the spin-lattice relaxation times T(1) has been measured in the wide temperature range of 4.2-420 K for morpholinium hydrogen chloranilate in which a one-dimensional O-HO hydrogen-bonded molecular chain of hydrogen chloranilate ions is formed. An anomalous temperature dependence of the NQR frequencies was analyzed to deduce a drastic temperature variation of the electronic state of the hydrogen-bonded molecular chain. The hydrogen atom distribution in the OHO hydrogen bond is discussed from the results of NQR as well as multi-temperature X-ray diffraction. Above ca. 330 K, the T(1) showed a steep decrease with an activation energy of ca. 70 kJ mol(-1) and with an isotope ratio (37)Cl T(1)/(35)Cl T(1) = 0.97 ± 0.2. The orientational change of the z axis of electric field gradient tensor in conjunction with the hydrogen transfer between adjacent hydrogen chloranilate ions is suggested as a possible relaxation mechanism. 相似文献
36.
Taka-Aki Shiraishi 《Annals of the Institute of Statistical Mathematics》1984,36(1):223-237
Summary Distribution-free tests for no treatment effect against the simple order alternative in a two-way layout with equal number
of observations per cell are considered. The nonparametric test statistics are constructed by the rank analogues of the likelihood
ratio test statistic assuming normality (i) based on within-block rankings and (ii) based on combined rankings of all the
observations after alignment within each block. The exact distributions are given and large sample properties are investigated.
The asymptotic power of the test (i) as the number of observations per eell tends to infinity can be satisfied enough, and
in the case that the number of blocks tends to infinity, the asymptotic power of the test (ii) is almost higher than that
of the test (i). Also these rank tests are compared with linear rank tests and it is shown that these proposed tests are robust
by a table. 相似文献
37.
Gyrgy Szllsi Shu-Ichi Niwa Taka-Aki Hanaoka Fujio Mizukami 《Journal of molecular catalysis. A, Chemical》2005,230(1-2):91-95
Systematic variation of the substrate structure in the enantioselective hydrogenation of α,β-unsaturated carboxylic acids over cinchonidine-modified Pd catalysts indicated that aryl substituents in β position changed the adsorption mode of the substrates on the metal surface and eventually the configuration of the products formed in excess as compared to aliphatic substrates. The configuration of the products formed in excess by hydrogenation of eight α,β-unsaturated carboxylic acids, of which two have not been described yet, indicated that the substrates bearing aromatic ring in β position were adsorbed on the opposite face of the CC group compared to acids having aliphatic group in β position. 相似文献
38.
Onoda A Yamada Y Nakayama Y Takahashi K Adachi H Okamura TA Nakamura A Yamamoto H Ueyama N Vyprachticky D Okamoto Y 《Inorganic chemistry》2004,43(14):4447-4455
Novel benzoic acid ligands with bulky amide groups at the ortho position, 2,6-(MeCONH)(2)C(6)H(3)CO(2)H (1) and 2,6-(t-BuCONH)(2)C(6)H(3)CO(2)H (2), and their tris- and tetrakis(carboxylate) complexes with Ca(II) and Tb(III) ions, (NEt(4))(2)[Ca(II)[O(2)C-2,6-(t-BuCONH)(2)C(6)H(3)](4)] (4), [Tb[O(2)C-2,6-(t-BuNHCO)(2)C(6)H(3)](3)(H(2)O)(3)]] (5), and (NMe)(4)[Tb[O(2)C-2,6-(t-BuNHCO)(2)C(6)H(3)](4)(thf)] (6), were synthesized. The formation of the NH...O hydrogen bonds between the amide NH and carboxylate for 2, (NEt(4))[2,6-(t-BuCONH)(2)C(6)H(3)CO(2)] (3), and 4 was determined by (1)H NMR spectroscopy in solution and in the solid state (CRAMPS, IR). The ligand exchange reactions were attempted between 4 and a large excess of 2,4,6- Me(3)C(6)H(3)CO(2)H in chloroform-d solution; however, exchange reaction did not take place, indicating that the Ca(II) ions bound strongly to the carboxylate in 4. The Ca(II) ion binding properties with the benzoate derivatives were also examined using Tb(III) ion as a fluorescence probe. These results indicate that the NH...O hydrogen bonding between the amide NH and the oxygen atom of the carboxylate contributes to strong Ca(II) binding and prevents the dissociation of the calcium-carboxylate bond. The X-ray structural analyses of these complexes revealed that the NH.O hydrogen-bonded carboxylate ligands prefer the chelate-type coordination and create a mononuclear [Ca(O(2)CR)(4)](2)(-) or [Tb(O(2)CR)(4)](-) core with anionic charge, which is known only in the active site of calcium-binding proteins. 相似文献
39.
40.
Nano/microstructure control and electrochemical etching of aluminium substrate using a honeycomb alumina mask fabricated by anodisation with self‐assembled spheres aligned on the aluminium surface were studied to directly control the initiation sites of pits. The transfer of the hexagonally ordered pattern of self‐assembled spheres to the aluminium substrate could be achieved by substantially suppressed anodic oxide growth under the spheres where selective electrochemical etching proceeded. That is, etch pits are generated only in the thinner areas or holes of the honeycomb alumina mask with a one‐to‐one correspondence. With this process, improvements in pit distribution density and the homogeneity of pit sizes, while avoiding excessive dissolution of the aluminium surface, could be achieved easily in comparison with the conventional method. The density of pits could also be controlled by changing the diameter of spheres used as an indirect mask. Copyright © 2010 John Wiley & Sons, Ltd. 相似文献