Electrochemical determination of quercetin by self-assembled platinum nanoparticles/poly(hydroxymethylated-3,4-ethylenedioxylthiophene) nanocomposite modified glassy carbon electrode

A simple and sensitive platinum nanoparticles/poly(hydroxymethylated-3,4-ethylenedioxylthiophene)nanocomposite(PtNPs/PEDOT-MeOH) modified glassy carbon electrode(GCE) was successfully developed for the electrochemical determination of quercetin.Scanning electron microscopy and energy dispersive X-ray spectroscopy results indicated that the PtNPs were inserted into the PEDOTMeOH layer.Compared with the bare GCE and poly(3,4-ethylenedioxythiophene)(PEDOT) electrodes,the PtNPs/PEDOT-MeOH/GCE modified electrode exhibited a higher electrocatalytic ability toward the oxidation of quercetin due to the synergic effects of the electrocatalytic activity and strong adsorption ability of PtNPs together with the good water solubility and high conductivity of PEDOT-MeOH.The electrochemical sensor can be applied to the quantification of quercetin with a linear range covering0.04-91 μmol L~(-1) and a low detection limit of 5.2 nmol L~(-1).Furthermore,the modified electrode also exhibited good reproducibility and long-term stability,as well as high selectivity.     

Identification of the Active Sites for Low Temperature CO Oxidation over Nanocrystalline Co3O4 Catalysts

The microstructural properties of dry‐grinding derived Co₃O₄ catalysts pretreated under different atmospheres, in relation to the activities on CO oxidation were investigated. The Co₃O₄ synthesized by soft reactive grinding and pretreated with O₂ resulted in the best activity, with 100% conversion of CO at ?52 °C, superior to that of Co₃O₄ pretreated with He. To find out the active sites on Co₃O₄ for low temperature CO oxidation, the characterizations of the cobalt oxides had been investigated by means of N₂ physisorption, XRD, TEM, H₂‐TPR, CO‐titration, XPS and O₂‐TPD technologies. XPS of Co2p results show that it is difficult to ascribe the difference in catalytic performance to the surface concentration of active Co³⁺ sites. A correlation between the activity and the CO‐titration and O₂‐TPD results for Co₃O₄ reveals that a high abundance of readily accessible superficial electrophilic oxygen (O^?) species is important for achieving a high activity. Therefore, CO oxidation takes place on the surface active oxygen sites in Co₃O₄ crystallites via the suprafacial mechanism.     

A cost-effective and practical polybenzanthrone-based fluorescent sensor for efficient determination of palladium (II) ion and its application in agricultural crops and environment

A highly selective and sensitive fluorescent chemosensor suitable for practical measurement of palladium ion (Pd²⁺) in agricultural crops and environment samples has been successfully fabricated using polybenzanthrone (PBA). PBA was facilely electrosynthesized in the mixed electrolyte of acetonitrile and boron trifluoride diethyl etherate. The fluorescence intensity of PBA showed a linear response to Pd²⁺ in the concentration range of 5 nM–0.12 mM with a detection limit of 0.277 nM and quantification limit of 0.925 nM. Different compounds existing in agricultural crops and environment such as common metal ions, anions, natural amino acids, carbohydrates, and organic acids were used to examine the selectivity of the as-fabricated sensor, and no obvious fluorescence change could be observed in these interferents and their mixtures. A possible mechanism was proposed that the coordination of PBA and Pd²⁺ enhance the aggregation of polymer chains, which led to a significant quenching of PBA emission, and this was further confirmed by absorption spectra monitoring and transmission electron microscopy. The excellent performance of the proposed sensor and satisfactory results of the Pd²⁺ determination in practical samples suggested that the PBA-based fluorescent sensor for the determination of Pd²⁺ will be a good candidate for application in agriculture and environment.     

由六亚甲基四胺和柔性芳香羧酸构筑的两个一维配位聚合物的合成及晶体结构

利用六亚甲基四胺分别与苯氧乙酸、Cu(NO₃)₂·3H₂O及2,4-二氯苯氧乙酸、Zn(NO₃)₂·6H₂O反应,得到了2个新的一维配位聚合物,{[Cu₂(pa)₄](μ₂-hmt)}_n(1)和{{{[Zn₃(dcpa)₄(OH)]₂(μ₂-dcpa)₂}(μ₂-hmt)}·5H₂O}_n(2)(Hpa=苯氧乙酸,Hdcpa=2,4-二氯苯氧乙酸,hmt=六亚甲基四胺)。2个配合物均用元素分析、红外光谱、X射线单晶衍射及差热分析进行了表征。晶体结构分析表明,在配合物1中,4个苯氧乙酸根桥联2个Cu²⁺形成[Cu₂(COO)₄]双核结构,相邻的[Cu₂(COO)₄]双核单元由六亚甲基四胺桥联成一维的"zigzag"链;在配合物2中,6个2,4-二氯苯氧乙酸根和2个OH^-桥联6个Zn²⁺形成六核{[Zn₃(dcpa)₄(μ₃-OH)]₂(μ₂-dcpa)₂}结构单元,然后相邻的六核单元由2个六亚甲基四胺桥联成一维双链结构。     

支持向量回归-同步荧光光谱法预测鸭肉中克百威残留

为了满足鸭肉中克百威残留分析及快速检测的要求,基于克百威水解物在巯基乙醇存在的条件下能与邻苯二甲醛反应产生具有强荧光性衍生物的方法,建立了应用同步荧光光谱法测定鸭肉中克百威残留量的预测模型。对含有克百威鸭肉样品的三维同步荧光光谱进行分析,确定其最佳波长差Δλ为120 nm;利用遗传算法(GA)结合交互验证均方根误差(RMSECV)从240～450 nm光谱中筛选出19个波长作为定量分析模型的输入特征变量;对SVR、PCR、PLS 3种回归模型的性能进行比较,实验发现SVR模型的预测结果最好,其预测集的决定系数(r2)和预测均方根误差(RMSEP)分别为0.999 4和0.878 7。研究结果表明,采用同步荧光光谱法结合支持向量回归算法测定鸭肉中克百威的残留量,具有快速、预测精度高等特点,可为检测鸭肉中的克百威残留量提供一种可行的方法。     

Electrochemical Determination of the Anticancer Herbal Drug Shikonin at a Nanostructured Poly(hydroxymethylated‐3,4‐ethylenedioxythiophene) Modified Electrode

A simple and sensitive method is described for the electrochemical determination of shikonin, a widely used anti‐tumoral agent, based on its electrochemical oxidation at a nanostructured poly(hydroxymethylated‐3,4‐ethylenedioxy‐thiophene) (PEDOT‐MeOH) electrode, which was fabricated by a facile electropolymerization method. Compared with bare and poly(3,4‐ethylenedioxythiophene) (PEDOT) electrodes, the PEDOT‐MeOH film exhibited a distinctly higher activity for the electrooxidation of shikonin. The PEDOT‐MeOH electrode showed a wide linear response for shikonin in the concentration range from 1.0 nM to 10.0 µM with detection limit of 0.3 nM. Furthermore, the PEDOT‐MeOH electrode displayed high stability, good reproducibility and high sensitivity for the detection of shikonin.     

基于3，5-二硝基苯甲酸和2，2'-联吡啶的Cu(Ⅱ)、Zn(Ⅱ)配合物的合成及晶体结构

以3,5-二硝基苯甲酸(3,5-Hdnbc)和2,2'-联吡啶(2,2'-bipy)为配体,与Zn²⁺和Cu²⁺反应,得到了4个配合物[Zn(3,5-dnbc)₂(2,2'-bipy)(H₂O)]·(3,5-Hdnbc)(1),[Cu(3,5-dnbc)₂(2,2'-bipy)(H₂O)](2),[Cu(2,2'-bipy)₂(3,5-dnbc)](NO₃)·2(3,5-Hdnbc)(3),和[Cu(2,2'-bipy)₂Cl](3,5-dnbc)·(3,5-Hdnbc)(4)。用元素分析、红外光谱对其进行了表征,并用单晶X-射线衍射测定了配合物的晶体结构;对配合物1和2进行了热重分析。4个配合物均为单核分子。配合物1中,Zn²⁺离子是五配位的三角双锥结构;配合物2中,Cu²⁺离子是五配位的变形四方锥结构;配合物3和4中,Cu²⁺离子均是五配位的三角双锥结构;配合物中存在氢键和π-π堆积等弱的分子间作用力。     

Microwave-assisted Syntheses,Structures and Bioactivities of a-Aminophosphonates Containing Pyrazole and 2-Hydroxybenzyl Units

Using 3-amino-4-cyanopyrazole, salicylaldehyde and dialkylphosphite as materials, a series of a-aminophosphonates containing pyrazole and 2-hydroxybenzyl units were synthesized under microwave irradiation without solvents and catalysts. The structures of the compounds were verified by IR, 1H NMR, J3C NMR and elemental analysis. The crystal structure of diisobutyl {a-[3- （4-cyano-lH-pyrazol）amino）]-N-（2-hydroxylbenzyl）}phosphonate （4d, C19H27N404P） was deter- mined by single-crystal X-ray diffraction. Compound 4d crystallizes in the orthorhombic system, space group Pbcn with a = 17.329（4）, b = 20.091（5）, c = 12.433（3）/k, V = 4328.7（17） A3, M,. = 406.42, Dc = 1.247 g/cm3, Z = 8, F（000） = 1728,μ = 0.158 mm-1, MoKa radiation （2 = 0.71073 A）, the final R = 0.064 and wR = 0.0169 for observed reflections with I 〉 2σ（I）. X-ray diffraction analysis reveals that two planes lie in 4d, and the dihedral angle is 85.76°. Intermolecular O（1）-H（1B）-O（2）, N（1）-H（1）-N（4）, N（3）-H（3）.-.N（2） and N（3）-H（3）...O（1） hydrogen bonds are found in the structure. All the compounds were evaluated for their antiviral and antitumor activities respectively. Among them, 4d and 4e showed moderate anti-TMV activities at 500 gg/mL, and 4e possessed excellent antitumor activity against PC3 cells at 10 gmol/L.     

Synthesis,Bioactivity and Crystal Structure Analysis of Diisopropyl[（4-cyanopyrazol-3-ylamino）（2-hydroxyl-phenyl） methyl]phosphonate

The title compound,diisopropyl[(4-cyanopyrazol-3-ylamino)(2-hydroxylphenyl) -methyl] phosphonate was synthesized by the addition reaction of diisopropyl phosphite and N-(4-cyanopyrazole-3-yl) -2-hydroxylphenyl-imine. Its structure was characterized by IR,1H NMR,elemental analysis and single-crystal X-ray diffraction. The crystal belongs to the triclinic system,space group P1 with a = 9.1840(13) ,b = 9.2278(13),c = 12.1952(17) ,α = 93.846(2) ,β = 90.947(2) ,γ = 111.289(2) °,V = 959.9(3) 3,Dc = 1.309 g/cm3,Z = 2,μ(MoKa) = 0.173,F(000) = 400,the final R = 0.0414 and wR = 0.1196 for 2985 observed reflections(I > 2σ(I)) . The pyrazole and benzene moieties are approximately coplanar in each case. The dihedral angle between planes 1 and 2 is 82.99°. The crystal structure is stabilized by three intermolecular hydrogen bonds of O(1) -H(1) …O(2) ,N(2) -H(2) …N(3) and N(2) -H(2) …O(1) . Preliminary bioassay indicated that the title compound possessed antiviral activity to some extent.