排序方式: 共有140条查询结果,搜索用时 9 毫秒
71.
72.
73.
Kanako Nakamae Takayuki Nakajima Yasuyuki Ura Yasutaka Kitagawa Tomoaki Tanase 《Angewandte Chemie (International ed. in English)》2020,59(6):2262-2267
By using a linear tetraphosphine, meso‐bis[(diphenylphosphinomethyl)phenylphosphino]methane (dpmppm), nona‐ and hexadecanuclear copper hydride clusters, [Cu9H7(μ‐dpmppm)3]X2 (X=Cl ( 1 a ), Br ( 1 b ), I ( 1 c ), PF6 ( 1 d )) and [Cu16H14(μ‐dpmppm)4]X2 (X2=I2 ( 2 c ), (4/3) PF6?(2/3) OH ( 2 d )) were synthesized and characterized. They form copper‐hydride cages of apex‐truncated supertetrahedral {Cu9H7}2+ and square‐face‐capped cuboctahedral {Cu16H14}2+ structures. The hydride positions were estimated by DFT calculations to be facially dispersed around the copper frameworks. A kinetically controlled synthesis gave an unsymmetrical Cu8H6 cluster, [Cu8H6(μ‐dpmppm)3]2+ ( 3 ), which readily reacted with CO2 to afford linear Cu4 complexes with formate bridges, leading to an unprecedented hydrogenation of CO2 into formate catalyzed by {Cu4(μ‐dpmppm)2} platform. The results demonstrate that new motifs of copper hydride clusters could be established by the tetraphosphine ligands, and the structures influence their reactivity. 相似文献
74.
Fukuji Higashi Takayo Shirai Kiyoshi Mitani Kanako Sugishita 《Journal of polymer science. Part A, Polymer chemistry》2001,39(22):3884-3892
A mixture of isophthalic acid (IPA) and terephthalic acid (TPA) was activated by a tosyl chloride/dimethylformamide/pyridine (Py) condensing agent in two steps via the treatment of a mixture of the initially activated IPA/TPA with additional TPA followed by the activation of TPA with the agent. The resulting mixture showed a solubility in Py different from that obtained by the activation of them all at once; the difference might be due to different structures of the aggregates of the activated IPA and TPA at the same composition of the diacids. The structures of the aggregates were evaluated on the basis of melting points and the IR spectra of a mixture of dimethyl esters of IPA and TPA produced by the quenching of the reaction mixtures with methanol. The mixture obtained by two‐step activation showed lower melting points and spectral changes due to enhanced associations of the esters with respect to the mixture prepared by the activation of them all at once. The aggregates were also examined in terms of the distributions of IPA and TPA in thermotropic copolyesters prepared from methylhydroquinone and chlorohydroquinone by their transition temperatures and 13C NMR. © 2001 John Wiley & Sons, Inc. J Polym Sci Part A: Polym Chem 39: 3884–3892, 2001 相似文献
75.
Kanno S Watanabe K Yamagishi I Hirano S Minakata K Gonmori K Suzuki O 《Analytical and bioanalytical chemistry》2011,399(3):1141-1149
A new thermoresponsive polymer separation column was applied to simultaneous analysis of four cardiac glycosides (CGs) being
widely used for the treatment of arrhythmias and heart failure in human blood and urine. This column is composed of an N-isopropylacrylamide polymer, the surface of which undergoes a reversible alteration from hydrophilic to hydrophobic by changing
temperature. The chromatographic separation and retention times can be easily be controlled by adjusting the column temperature.
As the column temperature was changed from 50 to 10 °C over 8 min, five CGs, including deslanoside, digoxin, methyldigoxin,
digitoxin, and digitoxigenin (internal standard) were better resolved. Using these LC conditions, we analyzed four CGs in
human whole blood and urine simultaneously by liquid chromatography-tandem mass spectrometry (LC-MS-MS). Validation data as
functions of recovery rates, linearity, accuracy, and precision were carefully tested; all were generally satisfactory. The
detection limits for the four CGs in both matrices were 0.2–0.3 ng/mL. The method was applied to analysis of methyldigoxin
and its main metabolite digoxin in whole blood and urine samples obtained from a deceased person in actual autopsy case. To
our knowledge, this is the first report describing an LC-MS-MS method using a thermoresponsive column for analysis of drug(s).
The inclusion of the thermoresponsive column in an LC-MS-MS technique seems to extend the possibility for simultaneous analysis
of compounds of different properties, such as hydrophobic precursors and their hydrophilic metabolites in biological samples
within limited analysis times. 相似文献
76.
Yoshinori SaitoMasato Hattori Yuko IwamotoYuriko Takashima Kanako MiharaYoko Sasaki Miho FujiwaraMisato Sakaoku Anna ShimizuXun Chao Chiaki Kuroda Xun Gong Ryo Hanai Motoo Tori 《Tetrahedron》2011,67(12):2220-2231
Root chemicals and DNA sequences were analyzed for Ligularialamarum samples collected in Yunnan and Sichuan Provinces of China and the relationship between the plant and Ligulariasubspicata, its taxonomically closest species, was examined. Both species produce furanoeremophilanes and eremophilan-8-one derivatives as the major components. Eleven new compounds, including a new seco-bakkane compound, were isolated. The two species were found to harbor overlapping intra-specific diversities with respect to the chemicals and the DNA sequences. 相似文献
77.
Motoo Tori Kanako Otose Hiroko Fukuyama Junko Murata Yasuko Shiotani Shigeru Takaoka Katsuyuki Nakashima Masakazu Sono Masami Tanaka 《Tetrahedron》2010,66(27-28):5235-5243
Eighteen new eremophilanes (dimeric lactones, lactams, carboxylic acid, methyl ester, tetranor- and dinor-ketones, furanoeremophilane, enoleremophilanolide, epoxyeremophilanolide, and hydroxy- or methoxyeremophilanolides) have been isolated from the methanol extract of fresh rhizomes of Farfugium japonicum (Compositae), and their structures have been determined on the basis of high-resolution 2D NMR and X-ray crystallographic analyses as well as by chemical transformations. 相似文献
78.
Kanako Takada Naoya Nakagawa Kunio Nikki Hiroshi Kimura 《Magnetic resonance in chemistry : MRC》1977,9(2):116-117
Aromatic solvent-induced shifts (ASIS) in 19F n.m.r. spectra of several organic fluoro compounds have been determined in several solvents. 19F n.m.r. signals of unsaturated fluoro compounds in C6F6 and C6H6 show excess high field shifts corresponding to the term σc (solvent shift caused by chemical interactions). The mechanism of this shift is discussed in connection with the presence of an F-π interaction. A thermal study also supports this idea. 相似文献
79.
Chimeric RNA Oligonucleotides with Triazole and Phosphate Linkages: Synthesis and RNA Interference 下载免费PDF全文
Dr. Tomoko Fujino Kanako Kogashi Koudai Okada Dr. Martin Mattarella Takeru Suzuki Dr. Kenichi Yasumoto Prof. Kazuhiro Sogawa Prof. Hiroyuki Isobe 《化学:亚洲杂志》2015,10(12):2683-2688
Chimeric RNA oligonucleotides with an artificial triazole linker were synthesized using solution‐phase click chemistry and solid‐phase automated synthesis. Scalable synthesis methods for jointing units for the chimeric structure have been developed, and after click‐coupling of the jointing units with triazole linkers, a series of chimeric oligonucleotides was prepared by utilizing the well‐established phosphoramidite method for the elongation. The series of chimeric 21‐mer oligonucleotides that possessed the triazole linker at different strands and positions allowed for a screening study of the RNA interference to clarify the preference of the triazole modifications in small‐interfering RNA molecules. 相似文献
80.
Inside Cover: Chimeric RNA Oligonucleotides with Triazole and Phosphate Linkages: Synthesis and RNA Interference (Chem. Asian J. 12/2015) 下载免费PDF全文