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141.
Xiao-Xiang Li Jun-Wen Wang Yu-Jing Guo Ling-Hong Kong Jing-Hao Pan 《Journal of inclusion phenomena and macrocyclic chemistry》2007,58(3-4):307-315
In phosphate buffer solution of pH5.4, the interaction of meso-tetrakis(2-thienyl)porphyrin(H2TTP) and Cu-meso-tetrakis(2-thienyl)porphyrin(Cu-TTP) with α-cyclodextrin(α-CD), β-CD, γ-CD, heptakis(2,3,6-tri-O-methyl)-β-CD(TM-β-CD)
has been studied by means of UV-vis, fluorescence and 1HNMR spectroscopy, respectively. The H2TTP and Cu-TTP can form 1:2 inclusion complexes with TM-β-CD and 1:1 inclusion complexes with the other three cyclodextrins.
In this paper, the inclusion constants (K) of H2TTP and Cu-TTP for the formation of the inclusion complexes have been estimated from the changes of absorbance and fluorescence
intensity in phosphate buffer solution. The inclusive capabilities of different kinds of cyclodextrins are compared. The result
shows that the inclusion ability of α-CD with H2TTP and Cu-TTP is the strongest among the three native CDs. The inclusion ability of modified β-CD with H2TTP and Cu-TTP is stronger, compared to the native β-CD, which indicates that the capacity matching plays a crucial role in
the inclusion procedure except for the hydrophobic effect. In addition 1HNMR spectra supports the inclusion conformation of the TM-β-CD-Cu-TTP inclusion complex, indicating the interaction mechanism
of inclusion processes. 相似文献
142.
根据在自由基引发剂存在下,8,9-苯并-2-亚甲基-1,4,6-三氧螺(4,4)壬烷(Ⅰ)可能存在的竞争反应,推导了动力学方程式。用红外光谱法测定了单体的消失速率和苯酞的生成速率。实验结果与推导动力学方程式相符。进一步证明了单体(Ⅰ)的增长反应由加成聚合和开环—异构化—加成这两个反应组成。这两个反应对总速率的相对贡献与单体浓度有关。得到了共聚物的结构。 相似文献
143.
144.
Zr(Y)O2衬底上大面积YBCO薄膜表面组织状态的研究 总被引:1,自引:0,他引:1
使用配备有EDS和ECP附件的SEM、AEM、和STM研究在750和800℃的Zr(Y)O2衬底上磁控溅射沉积的大面积YBCO超导薄膜的表面组织。YBCO薄膜为c轴取向单晶,但衬底温度为800℃时,膜表面的突出组织多为CuO颗粒,小坑较多,表面粗糙;衬底温度为750℃时,突出组织多为棒状和多边形123结构,很少小坑,表面较平整。 相似文献
145.
146.
147.
148.
Yong-Jiang Xu Weitao Pan Xin Chen Wai C. Wong Marc Labelle 《Tetrahedron letters》2005,46(44):7523-7526
Novel synthetic approaches toward 5,6-dihydro-pyrimido[4,5-b][1,4]oxazepines were reported that led to successful introduction of poorly reactive anilines and various 2-hydroxybenzaldehydes to this therapeutically relevant scaffold. More extensive SAR studies on this scaffold hence became possible. 相似文献
149.
Capillary electrophoresis with amperometric detection was applied to separate and determine protocatechuic aldehyde and protocatechuic acid in Salivia miltorrhrza preparations. The electrode used was a 0.3 mm diameter carbon disk electrode fixed in a wall-jet with amperometric detection. Under the optimum conditions, the two analytes were separated completely within 8 min. Excellent linearity was obtained in the concentration ranges of 0.25-100.0 microg ml(-1) and 0.50-100.0 microg ml(-1) for protocatechuic aldehyde and protocatechuic acid, respectively. The detection limits were 0.10 microg ml(-1) of protocatechuic aldehyde and 0.25 microg ml(-1) of protocatechuic acid, which were found to be lower than those of other methods that determine protocatechuic aldehyde (3,4-dihydroxybenzaldehyde) and protocatechuic acid (3,4-dihydrobenzoic acid) simultaneously. The mean recoveries of protocatechuic aldehyde and protocatechuic acid were 97.4% and 103.3%. This method has been successfully applied to monitor these two components in real samples such as Salivia miltorrhrza and its two traditional Chinese medicinal preparations. 相似文献
150.
Aqueous two-phase extraction as an effective tool for isolation of geniposide from gardenia fruit 总被引:5,自引:0,他引:5
Natural products are normally obtained by organic solvent extraction and many subsequent chromatographic separations. Compounds of interest are often isolated with very low yield and limited purity. An aqueous two-phase extraction process combined with a simple ethanol treatment, for removing excess inorganic salt, has been developed for preparation of geniposide from gardenia. The system was comprised of PE62, a random copolymer composed of 20% ethylene oxide and 80% propylene oxide, KH2PO4 and ethanol. To find optimal conditions, the partition behavior of geniposide under an aqueous two-phase system was investigated. Various factors were considered, including the concentration of salt, the concentration of polymer, the sample loading, and the addition of ethanol. The experimental results demonstrated that increasing salt concentration or decreasing PE62 concentration results in enhancement of the geniposide partition in the salt-rich phase. The addition of ethanol and higher sample loading also promoted the partition efficiency of geniposide. Based on this study, an optimized system containing 5% PE62, 7.5% KH2PO4, and 10% ethanol was tested on a large-scale extraction. A 39.0-g aliquot of final product (in powder form) with 77% purity of geniposide can be effectively extracted from 500 g of gardenia fruit. This process is proved to be useful for industrial application of geniposide preparation. 相似文献