Polyacrylamide and poly(itaconic acid) complexes

Intermolecular complex formation through hydrogen bonding between poly(itaconic acid), partially neutralized and non-neutralized, and polyacrylamide was studied by potentiometry. The complexes were obtained by template polymerization of itaconic acid and partially neutralized itaconic acid on polyacrylamide as a template. All the complexes were characterized by elemental analysis, FTIR spectroscopy and thermal analysis.     

相对滴定法的研究Ⅱ．电位滴定法测定多种弱酸的混合溶液

本实验研究了两种弱酸混合溶液中的相对滴定法。利用该法可分别检测ｐＫａ值相差１的两种弱酸混合溶液中的两种弱酸。     

Template assembled synthetic proteins: Condensation of a multifunctional peptide to a topological template via chemoselective ligation

A chemoselective ligation via oxime bond formation is used for the chemical synthesis of template assembled peptides according to the TASP (Template Assembled Synthetic Proteins) approach. Aminooxyacetylation of the multifunctional partial sequence Lys- Arg- Asp- Ser of lactoferrin and subsequent condensation in aqueous solution with a topological template containing four selectively addressable aldehyde functions as attachment sites gives readily access to the TASP molecule.     

Spectrofluorometric Determination of Hydrogen Peroxide

A Spectrofluorometric method for microdetermination of H₂O₂ has been developed. The method is based on the oxidation of hydrogen peroxide with ceric ion in acid solution and measurement of the fluorescence during titration of the Ce(III) ions produced. The fluorescent species have excitation and emission maxima at 260 and 360 nm, respectively. The detection limit of measurement by this method was 0.1 ppm hydrogen peroxide.     

贵金属的精密库仑滴定分析Ⅰ——金的纯度测定

本文用电生亚铜离子的精密库仑滴定法直接测定了金的纯度,研究了试样溶解处理条件、电极表面状态和终点电位检测精密度对滴定结果的影响。方法适用于含量为98～99.95%纯度金的分析。对于99.9%金的测定,相对标准偏差≤0.027%(n=6)。     

A novel fluorometric determination of melamine using cucurbit[7]uril

Melamine is a toxic compound to both animals and human beings, and is connected to various diseases, such as kidney stones and bladder cancer. For the efficient detection of melamine, we have developed a novel sensitive cucurbit[7]uril (CB7) sensor with a detection limit at 0.20 μg mL⁻¹, and applied it to detect melamine in tainted milk. Fluorescence studies indicate that CB7 forms complex with melamine in a 1:1 mole ratio. The binding constant at various temperatures has been calculated and the interaction mechanism has been discussed based on molecular modeling result.     

Transition-metal-complexed cyclic [3]- and [4]pseudorotaxanes containing rigid ring-and-filament conjugates: synthesis and solution studies

By using the "gathering-and-threading" effect of copper(I) with rigid ring-and-string conjugates, daisy-chain-type [3]- and [4]pseudorotaxanes could be prepared in high yields. The organic fragment used consisted of a 2,9-diphenyl-1,10-phenanthroline (dpp)-containing ring attached to a coordinating filament capable of threading through the ring of another molecule by coordination to copper(I). The bidentate chelate introduced in the axis was also a 1,10-phenanthroline (phen) derivative with two methyl groups ortho to the nitrogen atoms of the phen unit. The organic component was prepared following a multistep strategy, one of the key steps being the attachment of the ring to the lateral axis. This connection was done by a condensation reaction between an ortho dione located at the back of a ring-incorporated phen and an aromatic aldehyde, which was the end-function of the thread. An oxazole nucleus was obtained after the condensation, which provided a rigid connection between the ring and the axis. In this way, the coordination axes of the ring-incorporated bidentate chelate and of the ligand belonging to the lateral filament were approximately orthogonal to one another. The design was such that the tetrameric complex, a [4]pseudorotaxane, seemed to be the most stable species, owing to the mutual geometrical arrangement of the filament and the ring. Various spectroscopic techniques, such as (1)H NMR spectroscopy, including DOSY, and electrospray ionization mass spectroscopy (ESI-MS), clearly demonstrated that a mixture of cyclic [3]- and [4]pseudorotaxane was obtained; the proportions of both components depended on concentration and temperature. Copper(I) was not the only metal center leading to the formation of cyclic pseudorotaxanes. A similar effect was observed with silver(I) as the templating metal: quantitative formation of threaded species was observed, with a higher proportion of trimer over tetramer than in the copper(I) case. Concentration and temperature effects were investigated for both series of Cu(I) - and Ag(I) -complexed threaded species showing that formation of the trimer was favored upon dilution or heating of the solution.