微量法测定有机锡化合物中锡的含量

随着金属有机化学的不断发展,金属有机化合物中金属元素的分析显得日益重要。本微量法是用混合酸快速分解有机锡化合物,以EDTA络合剂和四价锡离子所生成的稳定的Sn~(+4)-EDTA络合物为依据,其过量的EDTA,用Pb(NO_3)_2、CuSO_4、ZnAc_2或La(NO_3)_3为滴定剂进行回滴,均得到准确的分析结果。此方法简单、快速、极易掌握操作技术;滴定     

Coumarins from campylotropis hirtella (FRANCH.) SCHINDL. and their inhibitory activity on prostate specific antigen secreted from LNCaP cells

Campylotropis hirtella (FRANCH.) SCHINDL. was used as a folk medicine for the treatment of benign prostate hyperplasia (BPH) in China. In this study, two new coumarins, 7,2',4'-trihydroxy-5-methoxy-3-arylcoumarin (1), 6-[(1S,2S)-2-angeloyloxy-1,3-dihydroxy-3-methylbutyl]-7-methoxycoumarin, named angelol M (2), together with eleven known related compounds (3-13) were isolated from this plant under the bioassay guided fractionation. All the compounds showed activity with different levels in inhibiting prostate specific antigen (PSA) secreted from androgen dependent prostate cancer cell line, LNCaP cells, using ELISA method.     

New Fluorescent Labels: 4- and 7-Chlorofluorescein

A new mixture of 4- and 7-chlorofluorescein were synthesized by condensation of resorcinol with 3-chlorophthalic anhydride in the presence of methanesulfonic acid or zinc chloride. These regioisomers were successfully separated by chromatography. The photophysical properties were examined and their absorption and emission maxima at long wavelength, high fluorescence quantum yield, and narrow emission bandwidth were found, highly favorable for detecting multiple target substances in the same sample. Furthermore, 4(7)-chlorofluorescein was found to be strongly pH-dependent between 4.0 and 8.0, and could be used as pH-sensitive fluorescent probe to measure intracellular pH.     

DFT Studies on the Isomerization of Butene Double Bond Catalyzed by 1-Butyl-3-methyl-imidazolium in Ionic Liquid

1 INTRODUCTION Butene and its isomers are important petroleum raw materials. Isomerization reaction of butene plays a key role in the course of C4 alkylation and its reaction mechanism has captured the attention of chemists all along[1, 2]. As a green so…     

氨基荧光素的合成、分离和表征

氨基荧光素的合成、分离和表征;氨基荧光素;硝基荧光素;还原;分离     

用紫外光谱和X射线光电子能谱研究金属卟啉自组装膜

金属卟啉化合物由于具有丰富的电子结构和特殊的物理化学性质,因而在光电材料、分子器件和非线性光学等领域具有广阔的应用前景．有机硅可用于提高高分子化合物在氧化物基底表面的附着力;在气相和液相色谱中可作为固定相;在生物传感器中可用于蛋白质的固定．     

Structural characterization of nanoparticles from thermoresponsive poly(N-isopropylacrylamide)-DNA conjugate

Poly(N-isopropylacrylamide) (PNIPAAm) grafted with single-stranded (ss) DNA conjugate (PNIPAAm-g-DNA) self-assembles above its lower critical solution temperature to form colloidal particles. When the ssDNA within the particle hybridizes with its complementary DNA, the particles aggregate above a certain threshold of salt concentration with drastically increased turbidity in solution. Detailed structural information of the particle was obtained mainly by small-angle X-ray scattering. The influence of copolymer composition on the morphology of particle and non-crosslinking aggregation was examined. The particle consists of hydrophobic PNIPAAm core surrounded by hydrophilic DNA strands. The increase in DNA fraction brought about a significant decrease in core size, whereas the shell thickness little changed and corresponded to the length of DNA. A structural model with a sticky potential was applied to the analysis of particle aggregate. This analysis provided that the particles aggregate while the coronal layers interpenetrate each other. The interaction between the particles was quantified in terms of the sticky potential and showed a trend to be influenced by the particle size rather than the graft density of DNA strands on the particle.     

298.15和308.15 K时1,2-丙二醇+MCl (M=Na,K, Rb,Cs)+H2O三元体系的溶解度、密度和折光率

系统研究了1,2-丙二醇+MCl (M=Na, K, Rb, Cs)+H₂O三元体系在298.15 和308.15 K时的等温相平衡. 采用硝酸汞滴定法测定了体系中无机盐的含量, 采用安东帕RXA170 折光率仪及DMA4500 密度计测定了所有体系的折光率和密度数值. 报道了1,2-丙二醇质量分数从0增加到0.9过程中饱和及不饱和三元溶液体系的等温溶解度、密度和折光率数据. 实验结果发现, 随着1,2-丙二醇的不断加入, 饱和溶液的溶解度和密度均呈现出减小的趋势, 而折光率的变化则呈现出相反的趋势. 采用经验方程关联了不同醇水比条件下不饱和溶液的密度和折光率实验数据, 获得了较为理想的拟合结果. 本研究的开展充实了碱金属盐在混合溶剂中的热力学数据, 为相关溶液化学研究奠定了基础.     

Combustion synthesis and electrochemical properties of the small hydrofullerene C50H10

The hydrofullerene C(50)H(10) is synthesized by low-pressure benzene-oxygen diffusion combustion. The structure of C(50)H(10) is identified through NMR, mass spectrometry, and IR and Raman spectroscopy as a D(5h) symmetric closed-cage molecule with five pairs of fused pentagons stabilized by ten hydrogen atoms. UV/Vis and fluorescence spectrometric analyses disclose its optical properties as comparable with those of its chloride cousin (C(50)Cl(10)). Cyclic and square-wave voltammograms reveal that the first reduction potential of C(50)H(10) is more negative than that of C(50)Cl(10) as well as C(60), with implications for the utilization of C(50)H(10) as a promising electron acceptor for photovoltaic applications.     

Aromatic annulation strategy for naphthalenes fused at 1,2- and 3,4-positions with two heterocycles

An efficient regioselective naphthoannulation strategy able to fuse a newly formed naphthalene ring at its 1,2- and 3,4- positions to two different heterocycles has been developed.