Spectrophotometric determination of cobalt in iron-, cobalt- and nickel-base alloys

A spectrophotometric method has been developed for the accurate determination of cobalt at milligram level, based on oxidation of the cobalt(II)-EDTA complex with gold(III) chloride at pH 4.0-6.5 and 100 degrees and measurement of the absorbance of the resultant violet cobalt(III)-EDTA complex at 535 nm. The precision is not affected by the presence of several metal ions; including coloured ones such as Cu(II), Ni(II) and Fe(III). However, chromium(III) interferes since it also forms a violet complex with EDTA, but can be removed by separation with pyridine. Practical application of the method is illustrated by the determination of cobalt in alloys based on iron, cobalt and nickel. Over the cobalt range 8-52% the error ranges from 0.1 to 0.3%.     

二吡啶甲基胺配合物修饰的肿瘤靶向性硅核壳纳米球(英文)

运用油包水微乳液方法制备了二吡啶甲基胺(dpa)及其锰(Ⅱ)和铁(Ⅲ)配合物修饰的Gd-DTPA配合物硅核壳纳米球,其中二吡啶甲基胺锰(Ⅱ)和铁(Ⅲ)配合物修饰的纳米球粒径分别为60和5nm。体外MRI成像研究表明3种纳米球能显著提高肿瘤细胞的磁共振成像效果,具备良好的肿瘤靶向性。生物活性数据显示三价铁配合物修饰的纳米球具备成像和抑制细胞生长的双重功能,而锰配合物修饰的纳米球不能抑制肿瘤细胞的生长,可作为低毒性的肿瘤成像剂。实验结果显示肿瘤靶向性配合物修饰的纳米球可发展成为新型多功能肿瘤靶向性纳米药物。     

Potentiometric estimation of sulfide ion using the Fe(III)-EDTA complex

The Fe(III)-EDTA complex reacts with sulfide ion in a fast electron transfer reaction, oxidising the latter to elemental sulfur and getting itself reduced to Fe(II). The reaction has been developed for the quantitative estimation of sulfide ion by titration against the Fe(III)-EDTA complex, measuring the redox potential of the system. Repeated use of a given quantity of the complex solution by the process of regeneration has been demonstrated. The possibility of its practical application in liquid phase oxidation processes of recovering sulfur from H₂S is emphasized.     

Zn(Ⅱ)-EDTA和Cd(Ⅱ)-EDTA在草酸根掺杂溴化银颗粒乳剂中的增感效应

使用反馈式微机控制双注乳化仪,在晶体生长过程特定时间内,加入一定量的草酸盐,制得了草酸根离子处于晶体次表面的立方体溴化银微晶乳剂,并对其进行传统的硫加金化学增感、Zn(Ⅱ)-EDTA或Cd(Ⅱ)-EDTA增感以及光谱增感.对实验过程的考察和感光性能的测试结果表明,Zn(Ⅱ)-EDTA或Cd(Ⅱ)-EDTA对细微粒溴化银颗粒乳剂均有显著的增感效应;Zn(Ⅱ)-EDTA或Cd(Ⅱ)-EDTA增感可在传统硫加金增感基础上与光谱增感协同作用,三者具有兼容和可加和性;Zn(Ⅱ)-EDTA或Cd(Ⅱ)-EDTA增感可在传统硫加金增感与光谱增感协同作用的基础上,与草酸根内部掺杂增感兼容,实现四者的协同作用,而不引起乳剂灰雾增加.     

含樟脑衍生物氰基桥联双金属配合物的合成、结构及磁性质

采用樟脑衍生物为配体，分别合成了氰基桥联Cu(Ⅱ)-Fe(Ⅲ)-Cu(Ⅱ)三核配合物[{Cu(D,L-La)₂}₂Fe(CN)₆](ClO₄) (1)和Mn(Ⅲ)-Fe(Ⅲ)双核配合物[Mn(D,L-Lb)(DMF)(Tp)Fe(CN)₃]·(H₂O)₆ (2)。晶体结构分析表明，化合物1中Cu(Ⅱ)离子处于五配位的配位环境，分别和1个D-La，1个L-La及[Fe(CN)₆]^3-中的1个氰基配位，2个Cu(Ⅱ)离子通过[Fe(CN)₆]^3-桥联。通过分子间氢键作用，化合物1形成二维超分子网络结构。化合物2中，[(Tp)Fe(CN)₃]^-通过其中的1个氰基与[Mn(D，L-Lb)]⁺桥联，其中Mn(Ⅲ)离子为六配位，分别和四齿配体Lb的2个氧原子和2个氮原子、DMF的1个氧原子及[(Tp)Fe(CN)₃]^-中的氰基氮原子配位。磁性研究表明，在化合物1中，Cu(Ⅱ)离子与Fe(Ⅲ)离子之间表现出铁磁相互作用，用哈密顿函数H=-2J(S₁·S₂+S₂·S₃)对其χ_MT-T曲线进行拟合，得到1的朗日因子g为2.190，交换常数J为0.55 cm^-1。     

Synthetic strategies for the surface functionalisation of gold nanoparticles with metals and metal clusters

The reaction of the new ditopic thiol-phosphine compound HS(CH(2))(11)OOCC(6)H(4)PPh(2) (L) with an excess of dodecanethiol-protected gold nanoparticles gave the asymmetric gold complex [CH(3)(CH(2))(11)SAuPPh(2)C(6)H(4)COO(CH(2))(11)SH] (4), but no phosphine-protected gold nanoparticles were formed. However, by blocking the phosphine function in L with metal fragments, we have been able to produce gold nanoparticles functionalised with AuCl- and cluster [Fe(2)(CO)(7)Au] units on the surface by the method of ligand-place exchange reaction.     

Interaction of 2- and 4-mercaptopyridine with pentacyanoferrates and gold nanoparticles

2-Mercapto- and 4-mercaptopyridine (2- and 4MPy) react with the [Fe(CN)(5)(H(2)O)](3-) complex, forming the S-coordinated [Fe(CN)(5)(2MPy)](3-) and the N-coordinated [Fe(CN)(5)(4MPy)](3-) complexes. The rates of formation and dissociation of the [Fe(II)(CN)(5)(2MPy)](3-) complex were determined as k(f) = 294 dm(3) mol(-1) s(-1) and k(d) = 0.019 s(-1) by means of stopped-flow technique. The equilibrium constants for the iron(II) and -(III) species were calculated as K(f)(II) = 1.5 x 10(4) mol(-1) dm(3) and K(f)(III) = 1.3 x 10(6) mol(-1) dm(3), in comparison with 2.6 x 10(5) and 3.4 x 10(4) mol(-1) dm(3), respectively, for the 4MPy isomer. In the presence of gold nanoparticles, both 2- and 4MPy can displace the stabilizing citrate species, leading to substantial aggregation in aqueous solution, as deduced from the surface-enhanced Raman spectroscopy effect and from the decay of the 520-nm plasmon band accompanied by the rise of the characteristic exciton band at 650 nm. The [Fe(CN)(5)(4MPy)](3-) complex promotes strong stabilization of the gold nanoparticles by interacting through the S atom. On the other hand, the labile [Fe(CN)(5)(2MPy)](3-) complex induces aggregation, delivering the 2MPy ligand to the gold nanoparticles.     

纳米金与磁性纳米复合物构建电流型免疫传感器的研究

制备了易于磁性分离、硫堇(Thi)包覆的四氧化三铁(Fe3O4)纳米复合物。通过静电吸附作用,将萘酚(Nafion)、Thi包覆的Fe3O4复合纳米粒子层层修饰到玻碳电极表面,再利用Thi分子中的氨基吸附纳米金,最后固载甲胎蛋白抗体,从而制得灵敏度高、稳定性好的无试剂电流型甲胎蛋白免疫传感器。实验通过透射电子显微镜(TEM)对该复合纳米粒子进行表征,并用循环伏安法考察了电极的电化学特性。结果表明,Fe3O4/Thi复合纳米粒子修饰的电极在实验过程中呈现出良好的氧化还原活性,其检测范围为0.05～20μg/L,检出限为0.03μg/L。     

金纳米粒子的阳光光化学合成和晶种媒介生长

在柠檬酸盐-HAuCl4溶液体系中, 于高原太阳紫外线辐射下光化学合成了分散良好、尺寸分布窄的胶体金纳米粒子. 研究了溶液的酸度和太阳辐射条件对Au(Ⅲ)离子光化学还原反应速率和形成金纳米粒子尺寸的影响; 采用晶种媒介生长技术, 通过改变Au(0)/Au(Ⅲ)比合成了平均直径为4.9~9.7 nm的球形金粒子. 根据紫外-可见吸收光谱和透射电子显微镜的表征和分析, 讨论了光化学反应中自由基反应、金纳米粒子成核和生长机理.     

阿霉素─铁(Ⅲ)配合物的电化学特征及其与DNA结合作用研究

采用示波极谱法和循环伏安法研究了3公铁离子Fe(Ⅲ)与阿霉素(ADM)配合物的电化学特性.在生理pH条件下,Fe(Ⅲ)与ADM形成2：1的稳定配合物,Fe(Ⅲ)的配位使ADM在更负的电势下才能还原,这与其心脏毒性减轻密切相关.采用线性扫描、吸收光谱和凝胶电泳法研究了ADM－Fe(Ⅲ)配合物与DNA的结合作用,ADM－Fe(Ⅲ)配合物仍保留了ADM插入结合的特征,并形成一种稳定的DNA－Fe(Ⅲ)－ADM的三元结合物.     

Fe(II)-EDTA chelate-induced aromatic hydroxylation of terephthalate as a new method for the evaluation of hydroxyl radical-scavenging ability.

The investigation of Fe(II)-EDTA chelate-induced aromatic hydroxylation of terephthalate in pH 7.4 phosphate buffer solution and a new method for the evaluation of hydroxyl radical-scavenging ability are reported. The method is based on attack of the hydroxyl radical on the terephthalate to produce highly fluorescent 2-hydroxyterephthalate, which is detected fluorimetrically. The formation of hydroxyl radical is believed to be the result of the reduction of molecular oxygen by Fe(II)-EDTA to form superoxide radical, which in turn dismutates to hydrogen peroxide, and then Fe(II)-EDTA catalyzes the decomposition of hydrogen peroxide to produce hydroxyl radical. The mechanism of the generation of hydroxyl radical in the proposed system was confirmed. This study established a simple and inexpensive method for the evaluation of the scavenging ability of some compounds on hydroxyl radicals.     

Iron oxide coated gold nanorods: synthesis, characterization, and magnetic manipulation

We report a simple process to generate iron oxide coated gold nanorods. Gold nanorods, synthesized by our three-step seed mediated protocol, were coated with a layer of polymer, poly(sodium 4-styrenesulfonate). The negatively charged polymer on the nanorod surface electrostatically attracted a mixture of aqueous iron(II) and iron(III) ions. Base-mediated coprecipitation of iron salts was used to form uniform coatings of iron oxide nanoparticles onto the surface of gold nanorods. The magnetic properties were studied using a superconducting quantum interference device (SQUID) magnetometer, which indicated superparamagnetic behavior of the composites. These iron oxide coated gold nanorods were studied for macroscopic magnetic manipulation and were found to be weakly magnetic. For comparison, premade iron oxide nanoparticles, attached to gold nanorods by electrostatic interactions, were also studied. Although control over uniform coating of the nanorods was difficult to achieve, magnetic manipulation was improved in the latter case. The products of both synthetic methods were monitored by UV-vis spectroscopy, zeta potential measurements, and transmission electron microscopy. X-ray photoelectron spectroscopy was used to determine the oxidation state of iron in the gold nanorod-iron oxide composites, which is consistent with Fe2O3 rather than Fe3O4. The simple method of iron oxide coating is general and applicable to different nanoparticles, and it enables magnetic field-assisted ordering of assemblies of nanoparticles for different applications.     

Colorimetric detection of Fe3+ ions using pyrophosphate functionalized gold nanoparticles

A sensitive, selective colorimetric Fe(3+) detection method has been developed by using pyrophosphate functionalized gold nanoparticles (P(2)O(7)(4-)-AuNPs). Gold nanoparticles were prepared by reducing HAuCl(4) with sodium borohydride, in the presence of Na(4)P(2)O(7). IR spectra suggested that pyrophosphates were capped on the surface of the gold nanoparticles. Aggregation of P(2)O(7)(4-)-AuNPs was induced immediately in the presence of Fe(3+) ions, yielding a color change from pink to violet. This Fe(3+)-induced aggregation of P(2)O(7)(4-)-AuNPs was monitored using first the naked eye and then UV-vis spectroscopy with a detection limit of 5.6 μM. The P(2)O(7)(4-)-AuNPs bound by Fe(3+) showed excellent selectivity compared to other metal ions (Ca(2+), Cd(2+), Co(2+), Fe(2+), Hg(2+), K(+), Mg(2+), Mn(2+), Na(+), Ni(2+), Pb(2+), and Zn(2+)). The best detection of Fe(3+) was achieved in a pH range from 3 to 9. In addition, the P(2)O(7)(4-)-AuNPs were also used to detect Fe(3+) in lake water samples, with low interference.     

Monodispersed core-shell Fe3O4@Au nanoparticles

The ability to synthesize and assemble monodispersed core-shell nanoparticles is important for exploring the unique properties of nanoscale core, shell, or their combinations in technological applications. This paper describes findings of an investigation of the synthesis and assembly of core (Fe(3)O(4))-shell (Au) nanoparticles with high monodispersity. Fe(3)O(4) nanoparticles of selected sizes were used as seeding materials for the reduction of gold precursors to produce gold-coated Fe(3)O(4) nanoparticles (Fe(3)O(4)@Au). Experimental data from both physical and chemical determinations of the changes in particle size, surface plasmon resonance optical band, core-shell composition, surface reactivity, and magnetic properties have confirmed the formation of the core-shell nanostructure. The interfacial reactivity of a combination of ligand-exchanging and interparticle cross-linking was exploited for molecularly mediated thin film assembly of the core-shell nanoparticles. The SQUID data reveal a decrease in magnetization and blocking temperature and an increase in coercivity for Fe(3)O(4)@Au, reflecting the decreased coupling of the magnetic moments as a result of the increased interparticle spacing by both gold and capping shells. Implications of the findings to the design of interfacial reactivities via core-shell nanocomposites for magnetic, catalytic, and biological applications are also briefly discussed.     

纳米金掺杂中空微胶囊的制备与表征

将表面含有双键的二氧化硅微粒分散在纳米金和聚乙烯吡咯烷酮溶液中.在此溶液中以聚乙烯吡咯烷酮为模板聚合物进行丙烯酸的模板聚合,得到二氧化硅为核、聚丙烯酸/聚乙烯吡咯烷酮/纳米金为壳层的核壳结构微粒.用氢氟酸将二氧化硅微粒去除后,得到了纳米金粒子掺杂的微胶囊.分别用扫描电子显微镜和激光共聚焦显微镜表征了微胶囊在干态和湿态下的形貌.通过电子衍射和透射电子显微镜确证了纳米金粒子在微囊壁上的存在和分布.     

STUDY ON THE DETERMINATION OF TRACE Fe(Ⅲ) BY THIN LAYER RESIN PHASE SPECTROPHOTOMETRY

A method to determine Fe(Ⅲ) by thin layer resin phase spectrophotometry has been developed in this paper. The colored complex formed by Fe(Ⅲ) and 1,2-benzendiol is concentrated on the 717# resin, then Fe(Ⅲ) can be determined directly by making thin layer. The method is sensitive with a apparent molar absorption of 4.8×104L/mol. cm, which is 16 times higher than that of liquid phase spectrophotometry, most coexisting ions do not influence the determination. The detection limit for Fe(Ⅲ) is 1.47μg/L with the precision of 3.3% [n=6, 7μg/50mL Fe(Ⅲ)]. The calibration curve is linear in the range of 0～25μg/50mL. The preposed method was applied to the determination of Fe(Ⅲ) in water sample with satisfactory results.     

Fe3O4/Polypyrrole/Au nanocomposites with core/shell/shell structure: synthesis, characterization, and their electrochemical properties

Uniform Fe3O4 nanospheres with a diameter of 100 nm were rapidly prepared using a microwave solvothermal method. Then Fe304/polypyrrole (PPy) composite nanospheres with well-defined core/shell structures were obtained through chemical oxidative polymerization of pyrrole in the presence of Fe3O4; the average thickness of the coating shell was about 25 nm. Furthermore, by means of electrostatic interactions, plentiful gold nanoparticles with a diameter of 15 nm were assembled on the surface of Fe3O4/PPy to get Fe3O4/PPy/Au core/shell/shell structure. The morphology, structure, and composition of the products were characterized by transmission electronic microscopy (TEM), scanning electronic microscopy (SEM), X-ray powder diffraction (XRD), and Fourier transform infrared (FT-IR) spectroscopy. The resultant nanocomposites not only have the magnetism of Fe3O4 nanoparticles that make the nanocomposites easily controlled by an external magnetic field but also have the good conductivity and excellent electrochemical and catalytic properties of PPy and Au nanoparticles. Furthermore, the nanocomposites showed excellent electrocatalytic activities to biospecies such as ascorbic acid (AA).     

光化学合成Au核@Pd壳复合纳米粒子及其表征

在PEG-丙酮溶液体系中, 采用紫外光辐射还原Au(Ⅲ), Pd(Ⅱ)离子混合物和以Au晶种为核、紫外光辐射还原Pd(Ⅱ)使其沉积在Au晶种表面上这两种方法, 合成了Au核@Pd壳复合纳米粒子. 通过改变Au(Ⅲ)离子或Au晶种对Pd(Ⅱ)离子的摩尔比调节复合粒子的尺寸和Pd壳厚度, 分别获得了直径范围为5.6~4.6 nm和4.6~6.2 nm的复合粒子. 利用UV-Vis吸收光谱、TEM、HR-TEM和XPS等表征手段, 证明了合成的纳米粒子为核-壳复合结构. 研究了Au@Pd纳米粒子的直径随溶液中Au(Ⅲ)/Pd(Ⅱ)摩尔比的改变而变化的规律; 对Au核向Pd壳的供电子作用以及复合粒子的光化学形成机理进行了讨论.     

Mechanistic analysis of gold(I)-catalyzed intramolecular allene hydroalkoxylation reveals an off-cycle bis(gold) vinyl species and reversible C-O bond formation

Mechanistic investigation of gold(I)-catalyzed intramolecular allene hydroalkoxylation established a mechanism involving rapid and reversible C-O bond formation followed by turnover-limiting protodeauration from a mono(gold) vinyl complex. This on-cycle pathway competes with catalyst aggregation and formation of an off-cycle bis(gold) vinyl complex.     

Facile synthesis of 4‐mercaptophenylboronic acid functionalized gold nanoparticles for selective enrichment of glycopeptides

In the work, 4‐mercaptophenylboronic acid (4‐MPBA)‐functionalized gold nanoparticles were synthesized via a facile approach. At first, gold nanoparticles (about 50 nm) were prepared by a simple and convenient hydrothermal method based on a polyol process. Then, gold nanoparticles were modified with 4‐MPBA by the well‐known reaction of Au with the thiol groups. The MPBA‐functionalized gold nanoparticles were characterized by Fourier transform infrared spectra and UV/Vis adsorption spectra. Due to the fact that the boronic acid group on the surface of 4‐MPBA‐modified gold particles can form tight yet reversible covalent bonds with glycopeptides containing cis‐1,2‐diols groups, the MPBA‐modified gold nanoparticles were successfully applied to selective enrichment of glycopeptides. Isolation and enrichment of glycopeptides in a standard protein (asialofetuin and horseradish peroxidase) digestion and a complex sample were performed using MPBA‐modified gold nanoparticles, followed by matrix‐assisted laser desorption/ionization quadruple ion trap time‐of‐flight (MALDI‐QIT‐TOF) mass spectrometric analysis. The experimental results demonstrated that MPBA‐modified gold nanoparticles synthesized by the facile approach have the powerful potential for selective enrichment of glyciopeptides, and can be an alternative tool in glycoproteomics. Copyright © 2009 John Wiley & Sons, Ltd.