有序介孔材料SBA-15吸附Ru（bpy）3^2＋修饰电极的电化学发光研究

制备了具有高比表面积且二维六方高度有序的介孔分子筛SBA-15,并采用TEM和氮气吸附实验对其结构性质进行了表征.利用静电作用将三联吡啶钌[Ru(bpy)32 ]固定到表面带负电荷的SBA-15上,并将吸附有Ru(bpy)32 的SBA-15修饰到玻碳电极表面,研究了该固定化的Ru(bpy)32 的电化学发光行为.结果表明,随着三丙胺(TPA)的加入,氧化电流增加而还原电流减小,表明TPA对三价吡啶钌有催化作用,同时TPA的加入显著增强了发光强度.随着扫描速率的增加,发光强度逐渐降低.SBA-15较大的孔径和开放交联的孔结构体系促进了电极表面膜内的物质扩散和电子运动扩散.该修饰电极在5.0×10-5~1.0×10-2mol/LTPA浓度范围内,发光强度与浓度具有良好的线性关系,线性方程为y=71.7 41.2x,检出限为9.5×10-6mol/L.该电极在连续扫描下具有较好的稳定性.     

银（Ⅰ）－硫脲－四正丁基溴化铵体系电致化学发光法测定水中痕量银

本文研究了银（Ⅰ）－硫脲－四正丁基溴化铵体系的电致化学发光（ＥＣＬ）。发现在正矩形脉冲下，银对含有硫脲的ＴＢＡＢｒ溶液的ＥＣＬ有明显催化作用，银（Ⅰ）的浓度在１．４×１０￣（－８）～３．５×１０￣（－６）ｍｏｌ／Ｌ范围内与ＥＣＬ强度呈良好线性关系。检出限为９．０×１０￣（－９）ｍｏｌ／Ｌ相对标准偏差为５％。用于天然水中银的测定，获得较满意的结果。     

Tris(2,2′-bipyridyl)ruthenium(II) electrogenerated chemiluminescence sensor based on carbon nantube dispersed in sol-gel-derived titania-Nafion composite films

A highly sensitive and stable tris(2,2′-bipyridyl)ruthenium(II) (Ru(bpy)₃²⁺) electrogenerated chemiluminescence (ECL) sensor was developed based on carbon nanotube (CNT) dispersed in mesoporous composite films of sol-gel titania and perfluorosulfonated ionomer (Nafion). Single-wall (SWCNT) and multi-wall carbon nanotubes (MWCNT) can be easily dispersed in the titania-Nafion composite solution. The hydrophobic CNT in the titania-Nafion composite films coated on a glassy carbon electrode certainly increased the amount of Ru(bpy)₃²⁺ immobilized in the ECL sensor by adsorption of Ru(bpy)₃²⁺ onto CNT surface, the electrocatalytic activity towards the oxidation of hydrophobic analytes, and the electronic conductivity of the composite films. Therefore, the present ECL sensor based on the CNT-titania-Nafion showed improved ECL sensitivity for tripropylamine (TPA) compared to the ECL sensors based on both titania-Nafion composite films without CNT and pure Nafion films. The present Ru(bpy)₃²⁺ ECL sensor based on the MWCNT-titania--Nafion composite gave a linear response (R² = 0.999) for TPA concentration from 50 nM to 1.0 mM with a remarkable detection limit (S/N = 3) of 10 nM while the ECL sensors based on titania-Nafion composite without MWCNT, pure Nafion films, and MWCNT-Nafion composite gave a detection limit of 0.1 μM, 1 μM, and 50 nM, respectively. The present ECL sensor showed outstanding long-term stability (no signal loss for 4 months).     

Energy Transfer Electrogenerated Chemiluminescence for the Determination of Sulfite

A simple and novel electrogenerated chemiluminescence (ECL) method for the determination of sulfite has been developed based on the energy transfer ECL process. It was found that a weak ECL signal of sulfite was electrochemically generated on a platinum electrode in neutral aqueous solution. The signal was strongly enhanced by rhodamine B as an energy receptor and further enhanced by the neutral surfactant Tween 80. In 0.10M phosphate buffer solution (pH=7.5) containing 2.0×10^–6gmL^–1 rhodamine B and 0.4% (v/v) Tween 80, the ECL response to the concentration of sulfite at a potential of 0.82V was linear over a range of 1.0×10^–7gmL^–1 to 8.0×10^–6gmL^–1, and the detection limit was 5×10^–8gmL^–1. The relative standard deviation (n=11, 1.0×10^–6gmL^–1) was 3.8%. The proposed method has been successfully applied to the determination of sulfite in pharmaceutical injections and white sugar samples.     

Heterogeneous and homogeneous electrochemiluminoimmunoassays of hTSH at disposable oxide-covered aluminum electrodes

Heterogeneous and homogeneous immunoassays of human thyroid stimulating hormone (hTSH) were developed on immunometric basis using aromatic Tb(III) chelates as electrochemiluminescent labels and varied types of disposable oxide-covered aluminum electrodes as the solid phase of the immunoassays. The long luminescence lifetime of the present labels allows the use of time-resolved electrochemiluminescence detection and provide the low detection limits of these labels and, thus, sensitive immunoassays. The primary antibody of immunometric immunoassays was coated upon aluminum oxide surface by physical absorption. In homogeneous immunoassays using 66 μl cell and 15 min incubation time, a linear calibration range of 0.25-324 μU/ml was obtained by applying only a single cathodic excitation pulse in the detection step of the assay.     

Determination of sophoridine and related lupin alkaloids using tris(2,2′-bipyridine)ruthenium electrogenerated chemiluminescence

Electrogenerated chemiluminescences (ECLs) based on tris(2,2′-bipyridine)ruthenium(II) (Ru(bpy)₃²⁺) and lupin alkaloids, for instance, sophoridine (SRI), matrine (MT), sophoranol (SR) and sophocarpine (SC) in an aqueous alkaline buffer solution (pH 9.0) are studied. The light emission is mainly caused by an electro-oxidation reaction between tertiary amino group on the alkaloid compounds and Ru(bpy)₃²⁺ in a thin layer flow cell equipped with a glassy carbon disc electrode (22.1 mm²) at the potential of +1.50 V (versus Ag/AgCl). The luminescence wavelength of 610 nm confirmed that ECL is caused by Ru(bpy)₃^2+∗ to its ground state. ECL intensities of these lupin alkaloids are affected by the substituent character, three-dimensional conformation of hydrogen on β-carbon atom. Ionization potentials taken from calculation data further confirm the experimental results. In addition, the factors affecting the determination and HPLC separation of the four alkaloids are also investigated.     

Electrogenerated Fe(I) Porphyrins: Efficient Electrocatalysts for Reductive Dechlorination of DDT in N,N′‐Dimethylformamide

Two iron(I) porphyrins were electrogenerated and then utilized as catalysts for the reductive dechlorination of 1,1‐bis(4‐chlorophenyl)‐2,2,2‐trichloroethane (DDT) in N,N′‐dimethylformamide. No reaction is observed between DDT and the Fe(III) or Fe(II) forms of the porphyrin, but the electrogenerated Fe(I) porphyrin efficiently catalyzes the electroreduction of DDT to give (1,1‐bis(4‐chlorophenyl)‐2,2‐dichloroethane) DDD, (1,1‐bis(4‐chlorophenyl)‐2,2‐dichloroethylene) DDE and (1,1‐bis(4‐chlorophenyl)‐2‐dichloroethane) DDMU as determined by GC‐MS analysis. The reductive dechlorination was monitored by electrochemistry, controlled potential electrolysis and spectroelectrochemistry and a mechanism for the reaction involving the reduced porphyrins and DDT is proposed. Comparisons are also made between the catalytic properties of metalloporphyrins containing iron, cobalt and manganese central metal ions under the same solution conditions.     

Electrogenerated acetonitrile anions/tetrabutylammonium cations: an effective catalytic system for the synthesis of novel chromeno[3′,4′:5,6]pyrano[2,3-d]pyrimidines

An efficient and convenient synthesis of novel chromeno[3′,4′:5,6]pyrano[2,3-d]pyrimidines is described, using the electrogenerated anion of acetonitrile as the base in the presence of tetrabutylammonium fluoride as an effective supporting electrolyte in a one-pot, three-component condensation of barbituric acid, an aromatic aldehyde or isatin, and 4-hydroxycoumarin. The reaction is carried out in an undivided cell containing an iron electrode as the cathode and a Pt electrode as the anode, at a constant current at room temperature.     

Highly Sensitive Electrochemiluminescent Insecticide Sensor Based on ZnO Nanocrystals Anchored Nickel Foam for Determination of Imidacloprid in Real Samples

In this work, a novel electrochemiluminescent (ECL) pesticide sensor based on zinc oxide nanocrystals decorated nickel foam is proposed for determination of imidacloprid for the first time. The silica film was used as a morphology‐controlling factor for modification of the electrode with zinc oxide nanocrystals. Zinc oxide was selected as luminescent material due to its cheapness, non‐toxicity, high thermal stability and excellent luminescence properties which truly adhered on the surface of nickel foam. The K₂S₂O₈ was used as strong co‐reactant for this purpose. The silica template plays an important role in controlling the size of ZnO nanocrystals. The Physical morphology of the ZnO/Ni‐foam electrode was performed by electrochemical impedance spectroscopy, Brunauer‐Emmett‐Teller (BET), X‐Ray diffraction analysis, field emission scanning electron microscopy, and energy‐dispersive X‐ray analysis. The ultra‐sensitive electrochemiluminescence method was successfully used for ultra‐trace determination of imidacloprid. The linear dynamic range and low detection limit were obtained 3×10^?14 ?8×10^?8 M and 4.4×10^?15 M, respectively. Also, the relative standard deviation for 15 repetitive optical signals was calculated 1.09 %.The present ECL sensor exhibited superior performance toward the accurate determination of imidacloprid with good reproducibility and stability.     

Facile preparation of 3-substituted 2-quinazolinones via electrogenerated base

A new series of 3,4-disubstituted quinazolin-2-ones, with potential T-type calcium channel antagonist activity, and new 4-methylene-quinazolin-2-ones, promising catalysts as N-heterocyclic olefins, have been prepared in good yield by a simple reaction between 2-aminobenzophenone, or 2-aminoacetophenone, and cyanomethyl anion electrogenerated by acetonitrile reduction at a graphite electrode, followed by the addition of different organic isocyanates and subsequent heterocyclization.