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21.
Toru Takagishi Naoki Matsui 《Journal of polymer science. Part A, Polymer chemistry》1987,25(9):2511-2520
The extent of binding of chrome violet, which is a monoazo dye and involves two hydroxyl groups in o and o′ positions to azo group, by polyvinylpyrrolidone is markedly enhanced in the presence of Co2+ ion. The amount of binding in the presence of 1 × 10?4 mol/L of Co2+ ion increases by a factor of about 10 compared to that in the absence of the metal ion. Ni2+ and Zn2+ ions do not perceptively influence the binding affinity of the dye. Cu2+ ion, in contrast, suppresses the binding. To investigate further the action of added metal ions, a cobalt–complex dye was prepared and its binding property for the polymer was compared to that of chrome violet in the presence of metal ions. Some possible mechanisms for the enhancement of chrome violet binding by the addition of Co2+ ion are described. 相似文献
22.
Ogawa T Araki M Miyamae T Okayama T Hagiwara M Sakurada S Morikawa T 《Chemical & pharmaceutical bulletin》2003,51(7):759-771
To improve the oral bioavailability of a dermorphin tetrapeptide analog, N(alpha)-1-iminoethyl-Tyr-D-MetO-Phe-MebetaAla-OH (III), which has a potent analgesic activity after oral administration, various derivatives were synthesized to increase lipophilicity by esterification of the C-terminal carboxyl group and/or acylation of the phenolic hydroxyl group on Tyr1. Antinociceptive activity was evaluated after subcutaneous or oral administration using the mouse tail pressure test. As a result, increased antinociceptive activity after oral administration as well as an improved ED50(p.o.)/ED50(s.c.) ratio, which is an indicator of oral bioavailability, were found for some compounds. With regard to the improvement of bioavailability, derivatives with acylation of the phenolic hydroxyl group on Tyr1 showed better results than derivatives with esterification of the C-terminal carboxyl group. In particular, an ED50(p.o.)/ED50(s.c.) ratio equivalent to that of morphine was found for an acetylated derivative, N(alpha)-1-iminoethyl-Tyr(COMe)-D-MetO-Phe-MebetaAla-OH (7a), as well as for a methoxycarbonylated derivative, N(alpha)-1-iminoethyl-Tyr(CO2Me)-D-MetO-Phe-MebetaAla-OH (7l). 相似文献
23.
Toru Sakaki Takaaki Harada Yohko Kawahara Seiji Shinkai 《Journal of inclusion phenomena and macrocyclic chemistry》1994,17(4):377-392
A criterion for the selection of a suitable plasticizer for calix[n]arene-based ion-selective electrodes is discussed. The cation selectivity of plasticized membranes without the ligand was first measured as a reference. The membranes can be roughly classified into two groups. The first group shows cation selectivity in the order Cs++>K+>Na+>Li+. The membranes in the second group are made of phosphorus plasticizers, which show a selectivity in the reverse order. The plasticizers in the first group featured a linear relationship between the dipole moment of the plasticizer (calculated by a PM3 method) and the ratio of cesium selectivity to lithium selectivity. The linear relationship supports the view that the polar membrane which includes a soft plasticizer with a large dipole moment shows selectivity for Cs+, whereas the nonpolar membrane including the soft plasticizer with the small dipole moment shows much lower selectivity for Cs+. Next, 2-fluorphenyl-2-nitrophenyl ether (FPNPE) which showed the highest Cs+ selectivity and tris(2-ethylhexyl)phosphate (TEHP) which showed the highest Li+ selectivity were mixed in an appropriate ratio to make membranes with a different affinity for hard ions. The metal selectivities of several crown-based and calixarene-based ionophores were examined in these membranes. Although a few exceptions exist, the polar soft membrane is favorable when the interfering metal ion is hard, whereas the hard membrane is favorable when the interfering metal ion is soft. 相似文献
24.
Toru Takagishi Sadatsugu Okuda Nobuhiko Kuroki Hiroshi Kozuka 《Journal of polymer science. Part A, Polymer chemistry》1985,23(8):2109-2116
Measurements have been made of the binding of divalent metal ions, Cu2+, Ni2+, Co2+, and Zn2+ ions, by polyethylenimine (PEI) and its acetyl or alkyl derivatives by the equilibriumdialysis technique. These metal ions, in particular the Cu2+ ion, exhibited tremendously remarkable binding affinity toward PEI. The extent of complexation of the polymer with the metal ions was decreased markedly by acetylation or alkylation of the polymer. PEI with no primary amine showed an appreciable decrease in its affinity for the metal ion. These results indicate the participation of the primary amine of the polymer in the formation of the complex. A cooperative binding isotherm was observed in PEI–metal ion complex formation, suggesting swelling or conformational change of the polymer induced by this coordination process. Binding of the Cu2+ ion by PEI was found to be essentially independent of temperature over the range 5–35°C. 相似文献
25.
Ultrasonic slurry sampling electrothermal atomic absorption spectrometry with a metal tube atomizer has been applied to the determination of lead in Bangladeshi fish samples. The slurry sampling conditions, such as slurry stabilizing agent, slurry concentration, pyrolysis temperature for the slurried fish samples, particle size and ultrasonic agitation time, were optimized for electrothermal atomic absorption spectrometry with the Mo tube atomizer. Thiourea was used as the chemical modifier for the interference of matrix elements. The detection limit was 53 fg (3S/N). The determined amount of lead in Bangladeshi fish samples was consistent with those measured in the dissolved acid-digested samples. The advantages of the proposed methods are easy calibration, simplicity, low cost and rapid analysis. 相似文献
26.
27.
Ihara M Katsumata A Setsu F Tokunaga Y Fukumoto K 《The Journal of organic chemistry》1996,61(2):677-684
[Ni(cyclam)](ClO(4))(2)-catalyzed indirect electroreduction of olefinic bromides produced six-membered compounds in low to high yields. The synthetic intermediate 49 of Ipecac and Corynanthe alkaloids was obtained in 88% yield in a highly stereoselective manner. Lactam 66, the synthetic precursor of tacamonine, was prepared in 49% yield as a mixture of two diastereoisomers. The electrolysis of the bromoacetates gave the debrominated compounds in good yields. 相似文献
28.
Toru Tachihara Susumu Ishizaki Yoshiko Kurobayashi Hiroshi Tamura Youichi Ikemoto Atsushi Onuma Keisuke Yoshikawa Tetsuya Yanai Takeshi Kitahara 《Helvetica chimica acta》2003,86(2):274-279
All possible stereoisomers of imine derivatives 1 – 4 , which have the characteristic roast odor of seafood, were synthesized. As a result of odor evaluation of all isomers, we found that each isomer has a different and characteristic odor of roasted seafood. 相似文献
29.
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