用石英晶体微天平研究表面活性剂在银固态表面上的动态吸附

吸附是表面活性剂的一个重要特征.迄今用于原位监测表面活性剂在固体表面上吸附重量变化的方法尚不多见.近年来压电石英晶体作为一种高灵敏的质量传感器(石英晶体微天平)已被用于大气和溶液中多种微量成分的监测.用石英晶体微天平研究I~-、Br~-和表面活性剂在金电极上的吸附行为亦有报道.本文研究了十六烷基三甲基溴化铵(CTAB)、十二烷基磺酸钠(SDSO)、十二烷基硫酸钠(SDS)在银固态表面上的吸附平衡动力学特性及其吸附机制.     

油溶性偶氮染料的合成及其性能研究

随着染料在现代科技中的广泛应用,染料的油溶性也日益受到人们的重视.如:非线性光学材料、激光盘光学信息存贮材料中使用的染料、彩色成像中的油溶性影像染料等,对染料在有机溶剂中的溶解度都有很高的要求.偶氮染料是有机染料中的主要类型,但目前对其分子结构与油溶性关系的研究甚少.本文合成了一类黄色偶氮染料(见表1),并对其色光、油溶性等性能进行了测试,发现取代基相对于偶氮基的位置,是影响偶氮染料油溶性的主要因素.     

银络合物在催化核上的还原反应

研究了尿嘧啶银络合物在胶态金属及其硫化物核上被对苯二酚还原的反应，并以Ａｇ和Ｐｔ电极代替催化核与对苯二酚显影剂和银络合物组成原电池作为电化学模型，分别测定该络合物阴极反应和对苯二酚阳极反应的电流。结果表明，原电池的电流大小与反应速度成正比关系，从而为物理显影电极理论提供实验依据。     

Determination of Labile Iron at Low nmol L−1 Levels in Estuarine and Coastal Waters by Anodic Stripping Voltammetry

A new method is presented for the determination of electrochemically labile iron in estuarine and coastal seawater. The method is based on differential pulse anodic stripping voltammetry (DPASV) at a rotating silver‐alloy disk electrode. The voltammetric parameters include a plating potential of ?1.5 V and an activation potential of ?5 V for 10s; the seawater is at the original sample pH. The main finding is the presence of a peak for low nmol L^?1 levels of iron at ?0.55 V ascribed to elemental iron deposited on the bare silver alloy electrode. The peak increased linearly with the iron concentration between <1 and 14 nmol L^?1 using a 900 s plating time. At higher concentrations an additional iron peak appeared at ?0.7 V which was also found to increase linearly with the iron concentration but at a higher concentration range from ca. 15 to 90 nmol L^?1 using a 300 s plating time. The second peak was ascribed to iron deposited on iron. Additions of chelating agents (EDTA and a siderophore) to seawater caused the iron peak to be masked indicating that this method is suitable for iron speciation as only the electrochemically labile fraction is determined. The detection limit was 0.3 nmol L^?1 using a 900 s plating time. The method was used to determine iron in the range of 5 to 50 nmol L^?1 in samples from the Mersey estuary near Liverpool and its potential use for in situ monitoring was demonstrated by using it to monitor labile iron (at 2–3 nmol L^?1) over a period of 4 days at 1 h intervals in coastal waters in the Trondheim fjord, Norway.     

过渡金属大环配合物的研究Ⅲ 4-硝基-苯并15冠-5与钴(Ⅱ)、铜(Ⅱ)和银(Ⅰ)配合物的合成及性质

有关冠醚配体与碱金属,碱土金属和稀土离子形成配合物的特性研究,国内外均有报导,但冠醚与d-过渡金属离子配合物的研究工作,则开展较晚,文献报导亦甚少。本文为探讨4-硝基-苯并15冠-5(No_2·B15C15)与过渡金属离子的配位能力,合成了Co(Ⅱ),Cu(Ⅱ),和Ag(Ⅰ)与4-硝基-苯并15冠-5配合物。并进行了元素分析,X-射线衍射,红外光谱,摩尔电导,激光拉曼光谱及差热-热失重分析的研究。     

Silver (I)-promoted asymmetric halohydrin reaction of chiral N-enoyl-2-oxazolidinones: scope and limitations

The halohydrin reaction of chiral N-enoyl-2-oxazolidinones 1 by halogen (Br₂/I₂) and water were efficiently carried out in aqueous organic solvent promoted by silver(I) with high anti- and regioselectivity and moderate to good diastereoselectivities. The alkenoyl, cinnamoyl and electron-deficient cinnamoyl substrates smoothly underwent bromohydrin reaction in aqueous acetone but no iodohydrin reaction, where as electron-rich cinnamoyl substrates preferred to undergo iodohydrin reaction in aqueous acetone with moderate diastereoselectivity and enhanced diastereoselectivity was observed in aqueous THF.     

粗糙化银电极上氰基钴胺素的电化学行为

比较研究氰基钴胺素在光滑和粗糙化银电极上的电化学行为，发现在光滑银电极上氰基钴胺素的还原为一个二电子过程，而在粗糙化银电极上则为两个一电子过程，其原因是由于粗糙化银电极对氰根的强吸附作用。     

Silver nanoparticles dispersed within amphiphilic star-block copolymers as templates for plasmon band materials

Formation of silver nanoparticles has been developed based on a template technique. Amphiphilic star-block copolymers employed as single molecule template, utilizing the coordination of Ag⁺ ions with carboxyl groups in the core of the star-block copolymer. Silver nanoparticles have been prepared by the addition of chemical reductant, e.g., NaBH₄. The solution of the resultant nanosphere composites showed yellow due to the surface plasmon resonance. These composites were soluble in organic solvents, because hydrophobic corona of the star-block copolymer protected the fabricated silver nanoparticles from aggregation.     

Synthesis and characterisation of advanced UHMWPE/silver nanocomposites for biomedical applications

A supercritical fluid (SCF) route for facile and homogeneous introduction of silver nanoparticles into polymer hosts is described. Our focus is on ultra-high molecular weight polyethylene (UHMWPE). We demonstrate that the metallic nanoparticles have a substantial effect upon the wear and tribochemical properties of the polymer substrate.     

On the Reactivity of Silver Electrodes in a Chlorine Radiofrequency Plasma — Plasma Oxidation vs. Thermal Oxidation

The plasma‐electrochemical growth of an ion‐conducting film by the oxidation of a metal in an electronegative plasma is investigated and compared with results from thermal oxidation. As model system we studied the oxidation kinetics of silver electrodes in a Cl₂ rf plasma. The electrochemical control of the reaction by external currents through the product layer using the plasma as a fluid electrode was achieved. Both potentiostatic and galvanostatic control of the reaction was applied. The morphology of the product layer and its temporal evolution was investigated using SEM. A formation of silver chloride surface patterns in the oxidation process takes place if a simple stability criterion is not fulfilled. Specific surface morphologies were found under different experimental conditions. The morphology of the product layer is influenced by the external electric current and the substrate temperature. The influence of the plasma phase on the thermodynamics and kinetics of the oxidation process is discussed. The role of excited plasma species, the electrical charging of the surface and radiation from the plasma are taken into account.