Solid-phase extraction of iron(III) with an ion-imprinted functionalized silica gel sorbent prepared by a surface imprinting technique

A new Fe(III)-imprinted amino-functionalized silica gel sorbent was prepared by a surface imprinting technique for selective solid-phase extraction (SPE) of Fe(III) prior to its determination by inductively coupled plasma atomic emission spectrometry (ICP-AES). Compared with non-imprinted polymer particles, the ion-imprinted polymers (IIPs) had higher selectivity and adsorption capacity for Fe(III). The maximum static adsorption capacity of the ion-imprinted and non-imprinted sorbent for Fe(III) was 25.21 and 5.10 mg g⁻¹, respectively. The largest selectivity coefficient of the Fe(III)-imprinted sorbent for Fe(III) in the presence of Cr(III) was over 450. The relatively selective factor (α_r) values of Fe(III)/Cr(III) were 49.9 and 42.4, which were greater than 1. The distribution ratio (D) values of Fe(III)-imprinted polymers for Fe(III) were greatly larger than that for Cr(III). The detection limit (3σ) was 0.34 μg L⁻¹. The relative standard deviation of the method was 1.50% for eight replicate determinations. The method was validated by analyzing two certified reference materials (GBW 08301 and GBW 08303), the results obtained is in good agreement with standard values. The developed method was also successfully applied to the determination of trace iron in plants and water samples with satisfactory results.     

有机试剂结构与性质的研究XII有机试剂的pKa与改进的Swain－Lupton参数

有机试剂的ｐＫ０ａ是其重要的物化参数，它是有机试剂酸碱性的度量，决定其配合物的稳定性．根据Ｓｗａｉｎ－Ｌｕｐｔｏｎ的工作，每个取代基的效应可用两个参数：场／诱导效应参数与共振效应参数来描述．本文应用Ｈａｎｓｃｈ改进的参数值研究了ｐＫａ与取代基常数的相关性，建立了下式．ｐＫａ＝ｐＫ０ａ＋ｒ１Ｆ＋ｒ２Ｒ     

1,5-苯并硫氮杂-α-苯基-β-内酰胺的合成及晶体结构

1，5-苯并硫氮杂与苯乙酰氯反应生成1，5-苯并硫氮杂-α-苯基-β-内酰胺（Ⅱ）。X-射线单晶衍射测定结果表明，该化合物分子式为C29H22CINOS，M=467.5，晶体属单斜晶系，P21／c空间群，a＝12．864（3），b=9．511（2），c=19．489（4）A，β=92.41（3）°，V=2382（1）A3，Dc=1．305g／cm3，Z=4，F（000）=976，μ=0．2636mm－1，R=0．068，Rw=0.068。该反应具有立体专一性，四员环上的2个苯基位于同一侧为顺式。产物分子中的七员环为类椅式构象。     

Biopolymer and carbon nanotubes interface prepared by self-assembly for studying the electrochemistry of microperoxidase-11

Stable films of biopolymer chitosan and carbon nanotubes were prepared by a layer-by-layer self-assembly technique. Atomic force microscopy, scanning electron microscopy, cyclic voltammetry, and UV-vis spectroscopy were used to characterize the film assembly. Atomic force microscopy and scanning electron microscopy showed that an even, stable film was formed. The UV-vis spectroscopy and cyclic voltammetry study indicated the uniform growth of the film. The property of the self-assembled multilayer film in promoting protein electron transfer was demonstrated by incorporating microperoxidase-11 in the film. Microperoxidase-11 in the multilayer film could transfer electrons with the electrode indicating that carbon nanotubes could wire the protein to the electrode. The electrocatalytic activity of the microperoxidase-11 containing multilayer film-modified electrode toward H(2)O(2) and O(2) was investigated. The results showed that along with the increase in the assembled layers the electrocatalytic reduction potentials of H(2)O(2) and O(2) shifted positively. The prepared multilayer film of chitosan and carbon nanotubes containing protein was a sensitive interface for electrocatalytic study.     

含金鸡纳碱的光活性聚合物──Ⅰ．金鸡纳碱／丙烯酰胺共聚物的合成与表征

研究了金鸡纳碱与丙烯酰胺的自由基共聚反应。发现在氯仿／乙醇混合溶剂中采用硫酸奎宁作为金鸡纳碱共聚单体可以合成收率和金鸡纳碱含量均较高的新型水溶性共聚物。对共聚物用元素分析、核磁共振、粘度和旋光度测定等方法进行表征，发现在假定丙烯酰胺链节为非光活性的条件下共聚物中金鸡纳碱链节的比旋光度随聚合配方中金鸡纳碱含量的增加而增加。     

Dual‐Amplification of Antigen–Antibody Interactions via Backfilling Gold Nanoparticles on (3‐Mercaptopropyl) Trimethoxysilane Sol‐Gel Functionalized Interface

A new dual‐amplification strategy of electrochemical signaling from antigen–antibody interactions was proposed via backfilling gold nanoparticles on (3‐mercaptopropyl) trimethoxysilane sol‐gel (MPTS) functionalized interface. The MPTS was employed not only as a building block for the electrode surface modification but also as a matrix for ligand functionalization with first amplification. The second signal amplification strategy introduced in this study was based on the backfilling immobilization of nanogold particles to the immunosensor surface. Several coupling techniques, such as with nanogold but not MPTS or with MPTS but not nanogold, were investigated for the determination of carcinoembryonic antigen (CEA) as a model, and a very good result was obtained with nanogold and MPTS coupling immunosensor. With the noncompetitive format, the formation of the antigen–antibody complex by a simple one‐step immunoreaction between the immobilized anti‐CEA and CEA in sample solution introduced membrane potential change before and after the antigen–antibody interaction. Under optimal conditions, the proposed immunosensor exhibited a good electrochemical behavior to CEA in a dynamic concentration range of 4.4 to 85.7 ng/mL with a detection limit of 1.2 ng/mL (at 3 δ). Moreover, the precision, reproducibility and stability of the as‐prepared immunosensor were acceptable. Importantly, the proposed methodology would be valuable for diagnosis and monitoring of carcinoma and its metastasis.     

Effect of additives on the stereochemical integrity and reactivity of alpha-alkoxycarbonyl alkenylcopper intermediates. Optimal conditions for the synthesis of isomerically pure tetrasubstituted alkenes

A systematic study on the effect of additives on the isomerizability of 1-alkoxycarbonyl alkenylcopper(I) intermediates revealed that the lithium chelator 12-crown-4 is significantly more efficient than HMPA at retarding isomerization. On the other hand, 12-crown-4 alone is unable to promote effective coupling with alkyl halides. The combination of 12-crown-4 and a reduced amount of HMPA, however, led to an improved procedure for the preparation of useful, isomerically pure tetrasubstituted alkenes such as allylation reagents and skipped dienes.     

Synthetic enantiopure aziridinomitosenes: preparation, reactivity, and DNA alkylation studies

An enantiocontrolled route to aziridinomitosenes had been developed from l-serine methyl ester hydrochloride. The tetracyclic target ring system was assembled by an internal azomethine ylide cycloaddition reaction based on silver ion-assisted intramolecular oxazole alkylation and cyanide-induced ylide generation via a labile oxazoline intermediate (62 to 66). Other key steps include reductive detritylation of 26, methylation of the N-H aziridine 56, oxidation of the sensitive cyclohexenedione 68 to quinone 70, and carbamoylation using Fmoc-NCO. Although the aziridinomitosene tetracycle is sensitive, a range of protecting group manipulations and redox chemistry can be performed if suitable precautions are taken. A study of DNA alkylation by the first C-6,C-7-unsubstituted aziridinomitosene 11a has been carried out, and evidence for DNA cross-link formation involving nucleophilic addition to the quinone subunit is described.     

Copper‐Bismuth Bimetallic Microspheres for Selective Electrocatalytic Reduction of CO2 to Formate

Electrocatalytic carbon dioxide reduction holds great promise for reducing the atmospheric CO₂ level and alleviating the energy crisis. High‐performance electrocatalysts are often required in order to lower the high overpotential and expedite the sluggish reaction kinetics of CO₂ electroreduction. Copper is a promising candidate metal. However, it usually suffers from the issues of poor stability and low product selectivity. In this work, bimetallic Cu‐Bi is obtained by reducing the microspherical copper bismuthate (CuBi₂O₄) for selectively catalyzing the CO₂ reduction to formate (HCOO^–). The bimetallic Cu‐Bi electrocatalyst exhibits high activity and selectivity with the Faradic efficiency over 90% in a wide potential window. A maximum Faradaic efficiency of ~95% is obtained at –0.93 V versus reversible hydrogen electrode. Furthermore, the catalyst shows high stability over 6 h with Faradaic efficiency of ~95%. This study provides an important clue in designing new functional materials for CO₂ electroreduction with high activity and selectivity.     

可交联聚甲基丙烯酸甲酯的合成、表征及在阵列式波导光栅中的应用

合成了含环氧基团的可交联的甲基丙烯酸甲酯和甲基丙烯酸环氧丙酯的共聚物[Poly(MMA-co-GMA)],通过FTIR,NMR,GPC,DSC和AFM等技术对其进行了表征. 结果表明,所合成的聚合物材料具有较好的成膜性; 通过热固化使引入的环氧基团开环交联,该聚合物的玻璃化转变温度(Tg)比固化前提高了24 K,同时有效地降低了聚合物的双折射率. 用Poly(MMA-co-GMA)作为包层材料,双酚A型环氧化合物作为高折射率材料, 将其引入到包层材料中形成芯层材料的折射率在波长1.55 μm处可调,其范围是1.483~1.588. 采用旋涂、 铝掩膜和氧反应离子刻蚀的方法(RIE)制得了阵列式光波导. 测试结果表明,制作的波导在1.55 μm处实现了光的单模传输,光损小于3.0 dB/cm.