丙醇-硫酸铵双水相体系萃取金(Ⅲ)-氯化物-罗丹明B

水溶性聚合物如聚乙二醇 (ＰＥＧ )、吐温(Ｔｗｅｅｎ) 80的水溶液在电解质存在下萃取分离贵金属离子已有报道[1] ;小分子的有机物如乙醇、丙醇在硫酸铵、氯化钠等电解质存在下也能分为两相形成双水相体系 ,可应用于金属离子的分离[2 ] ;该类体系也可以用于萃取分离贵金属络阴离子[3,4] 。我们发现金 (Ⅲ )与氯离子在碱性染料罗丹明Ｂ(ＲｈＢ)参与下所形成的三元缔合物 ,可被丙醇 硫酸铵双水相体系定量萃取而与大量常见贱金属分离 ,体系同时具有溶剂萃取法及溶剂浮选法的优点 :既可以分离简单贵金属络阴离子[3,4] ,又可以分离贵金属三元缔…     

Dynamics or Stochastic Conductance Switching of Phenylene–Ethynylene Oligomers?

Scanning tunneling microscopy (STM) studies of phenylene-ethynylene oligomers inserted in alkanethiolate self assembled monolayers (SAMs) are presented. Spontaneous changes in appearance of bundles of inserted molecules during imaging are observed. The results indicate that the appearance changes are caused by fluctuations of the number of molecules in the bundles, by diffusion and exchange of molecules, in contrast to previous reports which attribute the changes to stochastic conductance switching. The packing density of the SAM around the bundles of inserted molecules influence the fluctuations, as the fluctuations observed at 77 K all take place in bundles inserted at locally less-densely packed SAM areas. At room temperature fluctuations of bundles inserted in well-ordered areas are also observed.     

Kinetic Parameters of Gold Dissolution in Cyanide Solutions: The Effect of Complex Cyanide Ions of Mercury

The kinetics of the gold dissolution in cyanide solutions is studied at constant values of the coverage () of the gold surface by mercury atoms. The constancy of is ensured by maintaining an identical value of the duration (t) of contact of electrode with solution (after renewing its surface by cutting off a thin surface layer of metal) at a potential of –1.3 V, at which the discharge of mercury ions is limited by their diffusion to the electrode. At t = const kinetic dependences of the gold dissolution process correspond to the Tafel equation. Effective values of exchange current i ₀, transfer coefficient , and reaction order by cyanide ions P are determined. With increasing value of their magnitude increases from values 10^–5 A cm^–2, 0.1, and 0.17 that are characteristic of purely cyanide solutions (composition 0.1 M KCN, 0.1 M KOH, and 0.01 M KAu(CN)₂) to i ₀ 2 × 10^–4 A cm^–2, = 0.46, and P 1 at t = 270 s. These results are compared with the data obtained earlier during similar investigations in solutions containing thallium, lead, and bismuth. Common and individual features in the behavior of mercury-containing electrolytes are revealed. It is shown that the possible mechanism of the acceleration of the gold dissolution process in the presence of catalytically active atoms, which had been proposed in these works, may be used also for explaining the action of mercury atoms on this process.     

One-pot photoreduction to prepare NIR-absorbing plasmonic gold nanoparticles tethered by amphiphilic polypeptide copolymer for synergistic photothermal-chemotherapy

We developed one-pot photoreduction strategy to fabricate the NIR-absorbing plasmonic PLC-b-PEO@Au NPs. It possessed strong NIR absorption at 700-1100 nm, an ultrahigh photothermal conversion efficiency of 62.1%, and good photostability.     

Electrochemical Quartz Crystal Impedance Study of Glucose Oxidation on a Nickel Hydroxide Modified Au Electrode in Alkaline Solution

The electrochemical quartz crystal impedance (EQCI) technique has been applied to investigate glucose oxidation on bare and Ni(OH)₂‐modified Au electrodes in 0.2 mol L^?1 KOH aqueous solution. The EQCI responses suggest different contributions of H⁺‐release and OH^?‐incorporation reactions of the Ni(OH)₂‐film redox process in 0.2 mol L^?1 aqueous KOH at different potentials. Glucose adsorption on the Ni(OH)₂‐modified Au electrode was studied. A mechanism for potential cyclic redox process of glucose at Ni(OH)₂‐modified Au electrode is suggested, mainly based on a comparative EQCI analysis with direct glucose oxidation on bare gold and glucose ad‐/desorption on Ni(OH)₂ film.     

Conversion of nitrogen(I,II) oxides on nanodispersed [Pt(Pd)-Au]/HY zeolite catalysts

We have shown that conversion of nitrogen(I,II) oxides in reduction by carbon monoxide and light C₁, C₃–C₄ alkanes in the presence of nanodispersed [Pt(Pd)-Au]/HY catalysts is determined by the reagent activation routes in an oxidizing/reducing atmosphere. __________ Translated from Teoreticheskaya i éksperimental’naya Khimiya, Vol. 42, No. 3, pp. 156–161, May–June, 2006.     

Verbindungen in den Systemen Kalium(Rubidium)/Gold/Antimon: K3Au3Sb2, Rb3Au3Sb2 und K1,74Rb0,26RbAu3Sb2

Compounds in the Systems Potassium(Rubidium)/Gold/Antimony: K₃Au₃Sb₂, Rb₃Au₃Sb₂, and K_1,74Rb_0,26RbAu₃Sb₂ Brittle, silver coloured single crystals of K₃Au₃Sb₂, Rb₃Au₃Sb₂ and K_1,74Rb_0,26RbAu₃Sb₂ were obtainded by reaction of the alkali metal azides (KN₃, RbN₃) with gold and antimon powder at 550°C. The structures of the isotypic compounds (R3 m, Z = 3) were determined by X-ray single-crystal diffractometer data: K₃Au₃Sb₂, a = 6,198(2) Å, c = 21,520(5) Å, R/R_w (w = 1) = 0,046/0,058, Z(F) ? 3σ(F) = 175, Z(Var.) = 14; Rb₃Au₃Sb₂, a = 6,443(3), c = 21,69(2), R/R_w (w = 1) = 0,059/0,082, Z(F) ? 3σ(F₀²) = 258, Z(Var.) = 14; K_1,74Rb_0,26RbAu₃Sb₂, a = 6,288(2) Å, c = 21,617(5) Å, R/R_w (w = 1) = 0,049/0,069, Z(F) ? 3σ(F) = 390, Z(Var) = 14. The compounds crystallize with the K₃Cu₃P₂-structure type. The Au? Sb partial structures consist of [AuSb_2/3] layers with linear Sb? Au? Sb dumb-bells and SbAu₃ pyramids. The layers are separated by two crystallographically independent alkali metal atoms along [001].     

Photogeneration of nanosized gold on the surface of mesoporous silica modified by benzophenone

We have studied the photocatalytic activity of porous silicas (silica gel, mesoporous sol-gel films) modified by benzophenone molecules, in the reaction of reduction of gold from tetrachloroaurate ions. Stable colloids of nanosized gold were obtained as a result of irradiating aqueous alcoholic solutions of HAuCl₄·3H₂O in the presence of the photocatalyst SiO₂-BP using as the stabilizers: a colloidal solution of silica (Ludox) or the surfactant sodium dodecyl sulfate (SDS). We have studied the effect of the stabilizer on the kinetics of the photoreduction reaction, and also on the shape and size of the nanoparticles formed. __________ Translated from Teoreticheskaya i éksperimental’naya Khimiya, Vol. 41, No. 6, pp. 348–353, November–December, 2005.     

The simultaneous determination of gold and silver in blister copper and speiss products

A method for determination of silver and gold (concentration ranges of 0.1–0.4% and 8·10^–4–3·10^–3% respectively) in blister copper and speiss is described. Silver is determined directly in the solution after dissolution of the sample and appropriate dilution. The amount of gold is determined in an aliquot of the same solution after extraction with methyl isobutyl ketone. The relative standard deviation of the method described is 3.3% for speiss and 4.4% for blister copper for gold and 1.6% and 2.5% for silver respectively.     

Flame Atomic Absorption Spectrometric Determination of Gold and Palladium Using Microcolumn On-line Preconcentration and Separation

A microcolumn on-line preconcentration and separation system was developed for the flame atomic absorption spectrometric (FAAS) determination of trace levels of gold and palladium. The analytes were selectively adsorbed onto the microcolumn packed with 2-mercaptothiazole immobilized silica gel (MBTSG) in an acidity range of 0.1 to 6.0M HCl at a sampling flow rate of 4.0mLmin^–1. The analytes adsorbed could be desorbed by a thiourea solution with a flow rate of 2.0mLmin^–1. Most of the common coexisting metal ions at a concentration of 25.0mgmL^–1 and anions at a concentration of 50.0mgmL^–1 did not interfere with the preconcentration and determination of Au and Pd. The limits of detection (LOD), defined as three times the standard deviation of the blank (3), of Au and Pd are 10ngmL^–1 and 26ngmL^–1, respectively, with a preconcentration time of 60s. The relative standard deviation (RSD) is about 2.0% for 0.20µgmL^–1 Au and 0.30µgmL^–1 Pd. With a sample loading time of 30min, 6.7ngmL^–1 Au and 10ngmL^–1 Pd can be preconcentrated quantitatively. A geological sample, an anode slime and a secondary nickel alloy were successfully determined with the proposed method, and the results obtained showed good agreement with the certified values.Received December 23, 2002; accepted May 14, 2003 Published online August 8, 2003