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排序方式: 共有443条查询结果,搜索用时 31 毫秒
111.
Waki M Mizoshita N Ohsuna T Tani T Inagaki S 《Chemical communications (Cambridge, England)》2010,46(43):8163-8165
Periodic mesoporous organosilica with densely packed pyridine units within the framework and crystal-like molecular-scale periodicity was synthesized. The framework pyridines were chemically active and fully accessible for protonation and Cu(2+) adsorption. 相似文献
112.
113.
Hideyuki Yoshida Fumito Kido Makoto Yoshitake Kenichiro Todoroki Hitoshi Nohta Masatoshi Yamaguchi 《Analytical sciences》2007,23(4):485-488
A liquid chromatographic (LC) determination of catecholamines and indoleamines is described. This is based on intramolecular excimer-forming fluorescence derivatization with 4-(1-pyrene)butanoyl chloride, followed by reversed-phase LC. The analytes, containing an amino moiety and phenolic hydroxyl moieties in a molecule, were converted to the corresponding polypyrene-labeled derivatives by one-step derivatization. They afforded intramolecular excimer fluorescence, which can clearly be discriminated from the normal fluorescence emitted from reagent blanks. The detection limits (S/N = 3) for catecholamines and indoleamines were femto-mole levels per 20-microL injection. Furthermore, this method was applied to a urine assay. 相似文献
114.
Two types of laser-driven dry processes for the preparation of metal phthalocyanine are reported. In the first one, laser-driven metal exchange, the excimer laser beam was focused on a copper target, and ablated copper atoms were injected onto a thin film of dilithium phthalocyanine (Li2Pc). The central metal atoms of Li2Pc were partially exchanged by copper atoms, and the blue thin film of copper phthalocyanine (CuPc) was obtained after removal of the residual Li2Pc by the hydrochloric acid treatment. In the second one, direct synthesis using the component organic molecule, CuPc was prepared by the implantation of laser-ablated copper atoms onto a thin film of 1,3-diiminoisoindoline (D I I I). 相似文献
115.
Shimazaki Y Tani F Fukui K Naruta Y Yamauchi O 《Journal of the American Chemical Society》2003,125(35):10512-10513
The one-electron oxidized species of a Ni(II)-phenolate complex has been shown to be in the Ni(II)-phenoxyl radical state at room temperature and the Ni(III)-phenolate state at < -120 degrees C, indicating that the oxidation state is temperature dependent. 相似文献
116.
The local environments and dynamics of hydrogen atoms in five samples of protonated forms of ion-exchangeable layered perovskites, Dion-Jacobson-type H[LaNb2O7] and H[LaTa2O7], Ruddlesden-Popper-type H2[SrTa2O7] and H2[La2Ti3O10], and H1.8[(Sr0.8Bi0.2)Ta2O7] derived from an Aurivillius phase, Bi2Sr2Ta2O9, have been investigated by solid-state 1H nuclear magnetic resonance spectroscopy (NMR). Solid-state 1H NMR with a magic-angle spinning technique conducted at room temperature reveals that the mean electron densities around the 1H nuclei in these protonated forms are relatively low, and that they decrease in the following order: H1.8[(Sr0.8Bi0.2)Ta2O7]>H[LaNb2O7]>H2[SrTa2O7]>H[LaTa2O7]>H2[La2Ti3O10]. The temperature-dependent solid-state 1H broad-line NMR spectra measured at 140-400 K reveal a decrease in the signal width for all of these five samples upon heating due to motional narrowing. The NMR spectra of H[LaNb2O7] and H[LaTa2O7] are different from the other three protonated forms due to the weaker dipole-dipole interactions at low temperatures and lower mobility of the hydrogen atoms at high temperatures. 相似文献
117.
Hioki K Kobayashi H Ohkihara R Tani S Kunishima M 《Chemical & pharmaceutical bulletin》2004,52(4):470-472
Weinreb amides were successfully prepared from the corresponding carboxylic acids using 4-(4,6-dimethoxy-1,3,5-triazin-2-yl)-4-methylmorpholinium chloride (DMT-MM) in the solvents, methanol, isopropyl alcohol, and acetonitrile, which can solubilize DMT-MM. A variety of carboxylic acids were converted to the corresponding Weinreb amides in excellent yields by simply mixing with DMT-MM and N,O-dimethylhydroxylamine hydrochloride. 相似文献
118.
Low-temperature polymerization of α-pyrrolidone, α-piperidone, and ?-caprolactam was examined by using the salts derived from NaAlEt4 and monomer, sodium lactamates, or the salt derived from AlEt3 and monomer as catalyst and with N-acetyl lactams, ethyl acetate, or lactones as initiator. Sodium lactamate catalyst gave unsatisfactory results in the cases of ethyl acetate or lactones initiators, and gave the following order for the relative efficiency of initiators: N-acetyl lactam > ?-caprolactone ≥ ethyl acetate > β-propiolactone. The polymerization results obtained by the salt from NaAlEt4 catalyst–ethyl acetate initiator system were nearly the same as those with N-acetyl lactam. The increases in the degree of polymerization and in the yield of polymer were observed in case of the salt from NaAlEt4 catalyst-lactone initiator system, particularly in the cases of α-piperidone and ?-caprolactam. Also an incorporation of initiator into polymer chain was observed. 相似文献
119.
Tadashi Nakata Takaaki Kuwabara Yōichirō Tani Takeshi Oishi 《Tetrahedron letters》1982,23(9):1015-1016
()-Oudemansin has been synthesized starting from -cinnamaldehyde by a route involving the stereoselective Zn(BH4)2 reduction of β-keto ester. 相似文献
120.
H. Yasuda K. Fujita S. Yamamoto H. Tani 《Journal of polymer science. Part A, Polymer chemistry》1973,11(6):1421-1434
Stereospecific polymerization of acetaldehyde was examined by using four possible purified diethylaluminum butoxides, (Et2AlOBu)2 [Bu = n-, i-, sec-, or tert-Bu], as catalyst. These catalysts gave isotactic polyacetaldehyde quantitatively irrespective of the degree of branching of the butyl group, only when an optimum amount of water (about 0.03 mole/mole of catalyst) was added to the purified acetaldehyde monomer. Quite similar results were obtained for organozinc catalysts. These results indicate that water is an indispensable cocatalyst in the polymerization reaction with organoaluminum and zinc catalysts. An novel coordinate cationic mechanism was proposed for the stereospecific polymerization of acetaldehyde with organoaluminums, based on the above phenomena and on the inactivation of the catalyst by forming a complex with a strong Lewis base. 相似文献