Electropolymerization of diaminofluorene and its electrochemical properties

AbstractPoly 2,7-diaminofluorene (PDAF)/Au modified electrode was prepared using 2,7-diamino fluorene (DAF) dissolved in acetonitrile (ACN) containing 0.1M LiClO4 using consecutive multisweep cyclic voltammetry (CV) and controlled potential electrolysis (CPE) techniques. Factors affecting the film formation, such as limits of potential cycling, sweep rate, number of sweeping cycles, monomer concentration, and also polymerization techniques were examined in detail. It was found that the optimum conditions, using a potentiodynamic technique on Au electrode as the working electrode, are by sweeping the potential between –200mV and 800mV at a sweep rate of 50mV/s for 10 cycles using 5mM DAF monomer solution. The obtained modified electrode was active only in acidic aqueous solutions (pH range from 0 to 2) and its activity was found to be pH dependent. PDAF was isolated and characterized using UV–vis, 1HNMR and SEM analyses. The electrical conductivity was found to be 1.5×10−5Scm−1. An electropolymerization mechanism was proposed and discussed based on the obtained experimental data and molecular orbital calculations. The obtained modified electrode has been found to improve the electrochemical reversibility and decrease the overpotential of hydroquinone. PDAF/Au was stable chemically and electrochemically both in aqueous and organic solutions, making it an excellent candidate for sensing and/ or electrocatalytic applications

Tautomerism of Some 5-Arylazo-2-thiohydantoin Derivatives as a Criterion of Their Acidity

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Electrochemical behaviour of some 1,3,4-thiadiazole derivatives: Part 2 - Effect of acid and base on electro-oxidation mechanism of 2-benzoylamino- 5-( 1-cyanoarylhydrazono )-1,3,4-thiadiazoles at a platinum anode

864-867The oxidation of the title compounds in acetonitrile containing LiClO4 as supporting electrolyte, in both acidic and basic media, has been studied by cyclic voltammetry, coulometry and preparative electrolysis. In the presence of HClO4, the compounds are oxidized in the protonated forms and the main products are the corresponding perchlorate salts, whereas in media containing γ-collidine, the anion is the oxidizable moiety and the 4-aminocinnoline derivative is the main product. Mechanism of electrochemical oxidation is proposed and discussed

Composite Films of Metal Hexacyanoferrate and Poly (1,8-diaminonaphthaline) Derivatives: Electrosynthesis and Properties

The details of a potentiodynamic preparation method for a composite nickel(II) and copper(II) hexacyanoferrate (MeHcF) and poly[8-(3-acetylimino-6-methyl-2,4-dioxopyran)-1-aminonaphthaline] (PAMDAN) on a platinum electrode, (Pt |PAMDAN|MeHcF) are reported. The cyclic voltamograms recorded the direct deposition and growth of inner layer (PAMDAN) and the outer layer (MeHcF) from their solutions. The two composite electrodes show an improvement in the redox response. The voltammetric characteristics of the composite modified electrodes were also investigated in presence of different alkali metal cations (Li+, Na+, K+ and NH4+). The heterogeneous electron transfer processes involving the composite and their stability were examined by subjecting the system to the long term cyclic voltammetric potential cycling in 0.2 M NaCl electrolyte also after exposing the modified electrode to air for about 48 h then cycled in 0.2 M NaCl solution. Bilayer composite electrodes exhibit higher ionic conductivity, higher stability in comparison with pure inorganic (MeHcF) films. The inner electroactive polymer chains in the film cause enhancement in the electric conductivity of the composite electrodes

Electrochemical Reduction and Stripping Voltammetric Determination of the Anti-Glaucoma Drug Levobunolol HCl in Formulation and Human Serum at the Mercury Electrode

Levobunolol HCl is a potent non-selective ß-adrenoceptor blocking agent used for the topical treatment of increased intraocular pressure in patients with chronic open angle glaucoma or ocular hypertension. Precise, rapid and extraction-free square-wave adsorptive cathodic stripping voltammetry (SW-AdCSV) method has been described for trace quantitation of levobunolol HCl in bulk form, commercial formulation (ophthalmologic drops) and human serum. Limits of quantification (LOQ) of 1.0 × 10-10 mol L-1 (in bulk form) and 2.5 × 10-10 mol L-1 levobunolol HCl (in spiked human serum) were achieved by the described method. Insignificant interferences from excipients associated with formulation of levobunolol HCl and from some common metal ions, co-administrated drugs, some other ß-blocker agents and its metabolite dihydrolevobunolol that are likely to be present in the biological fluids were obtained. The described SW-AdCSV method is sensitive enough to assay the drug in human serum compared to most of the reported methods