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101.
Toru Takagishi Kimio Nakagami Koichi Imajo Nobuhiko Kuroki 《Journal of polymer science. Part A, Polymer chemistry》1976,14(4):923-929
The binding of methyl orange, ethyl orange, propyl orange, and butyl orange by poly(vinylpyrrolidone) has been examined by a technique of equilibrium dialysis over a high temperature range (60–90°C). The first binding constants and the thermodynamic parameters in the course of the binding were evaluated. The results obtained at these temperatures were compared to those at lower ones (5–35°C) described previously in order to estimate the contribution of hydrophobic bonds to the binding. It was found that at the 60–90°C range complex formation between the dye and the macromolecule is associated with an exothermic enthalpy change and a positive entropy change. The enthalpy and entropy changes of the binding are of the order of ?4.5 kcal/mole and 6 eu, respectively, for each dye measured. Thus the binding is mainly enthalpy-controlled. Furthermore the effect of the alkyl chain length of the dye on both the ΔH° and ΔS° values is not pronounced. Also temperature dependences of the ΔH° and ΔS° terms were not observed. All these observations in the higher temperature range can be explained as a result of the disruption of water structure in the binding environment and hence a decrease in hydrophobic bond formation between the dye and the polymer. 相似文献
102.
103.
Three polymethine dyes, which fluoresce at 780–820 nm, are separated by reversed-phase chromatography and detected fluorimetrically with a semiconductor laser for excitation. The detection limit for anhydro-3,3,3′,3′-tetramethyl-1,1′-bis(4-sulfomethyl)-4,5,4′,5′-dibenzoindotricarbocyanine hydroxide (sodium salt) is 0.3 pg, which is almost three orders of magnitude better than the value obtained by conventional fluorimetry. 相似文献
104.
105.
106.
Local densities of states are calculated by use of a cluster model. Resonant states due to Cl 3p orbitals appears in the valence band. The calculated energy-splittings between non-bonding px(py) and bonding pz orbitals agree well with the observed ones. 相似文献
107.
Noriyoshi Kon Nobuhiko Iki Yusuke Yamane Shin Shirasaki Sotaro Miyano 《Tetrahedron letters》2004,45(1):207-211
2,14-Dithiacalix[4]arene 34 was conveniently prepared in 16% yield by acid-catalyzed cyclocondensation of 2,2′-thiobis[4-tert-butylphenol] with formaldehyde. The present method also afforded the first isolation of the analogues with six and eight phenol units, 36 (10%) and 38 (5%), respectively. Solvent extraction showed that 34 had high selectivity toward Cu2+ ion at pH 5.5 by coordination of the bridging sulfur with cooperative donation of the adjacent phenolate oxygens. 相似文献
108.
109.
Funabiki T Sugio D Inui N Maeda M Hitomi Y 《Chemical communications (Cambridge, England)》2002,(5):412-413
Catechol dioxygenase model oxygenations have been performed for the first time in water by using water-soluble nonheme iron(III) complexes, enabling the oxygenation of protocatechuic acid and other catechols. 相似文献
110.
Takeshi Sakaizumi Hirotaka Imajo Ryo Sekiya Nobuhiko Kuze Osamu Ohashi 《Journal of Analytical and Applied Pyrolysis》2001,60(2):131-144
The pyrolysis products of CH2=C(CH3)---NO (syn form) have been determined by microwave spectroscopy. The pyrolysis products of CH2=C(CH3)---NO (syn form) and its 15N isotopic species were found to be CH2=O, CH3CN, and CH3C15N. The produce of formaldehyde and methyl cyanide suggests that the C=C and N=O double bonds of CH2=C(CH3)---N=O (syn form) were broken. To explain the generation of the two molecules, a four-membered ring molecule (9) as an intermediate, is proposed. The four-membered ring molecule as an intermediate is also supported by ab initio MO calculation. Applying the pyrolysis mechanism obtained for 2-nitrosopropene (syn form) to that of 1,1,2-trichloronitrosoethane, one of its complicated pyrolysis mechanisms was explained. The rotational constants and geometrical parameters of two intermediates, 9 and CH2=CCl---NO (13), were obtained by ab initio MO calculation (MP2/6-31G**) to predict their microwave spectra. 相似文献