Electrochemistry of [ReIII(DIARS)2Cl2]Cl, Where DIARS=o-Phenylenebis(dimethylarsine), in Aqueous and Aqueous/Ethanol Solvents at Bare and Nafion-Modified Electrodes

Abstract

The electrochemistry of [Re III (DIARS) 2 Cl 2 ]Cl in aqueous and aqueousyethanol solvents at bare and Na®on-modi®ed electrodes has been studied by cyclic voltammetry, differential pulse voltammetry, and chronocoulometry. .93 phosphate buffer, and aqueous pH 6.93 phosphate buffer solutions gave formal reduction potentials that fall within the range of À0.319 V to À0.263 V (vs. AgyAgCl) and increase with the dielectric constant of the solvent. In 33 % ethanolyaqueous pH 6.93 phosphate buffer and aqueous pH 6.93 phosphate buffer, both the oxidized and reduced forms of the complex exhibited adsorption at the surface of gold electrodes as shown by cyclic voltammetry and chronocoulometry. An especially sharp reduction wave, which is more negative than the reduction wave in subsequent cycles, was obtained on the ®rst scan in cyclic voltammetry. By comparison, well-de®ned voltammograms were obtained at Na®on-modi®ed glassy carbon. Substantial partitioning into Na®on occurred and a detectable signal was measured for Na®on coated glassy electrodes at concentrations as low as 4X0 Â 10 À10 M by differential pulse voltammetry. Na®on also prevented uric acid, dopamine, DOPAC, and ascorbic acid from interfering with the electrochemical detection of [Re , which is potentially useful for the study of its imaging properties in nuclear medicine.

Electrochemical Investigation of Dopamine at the Water/1,2-Dichloroethane Interface

“…On one hand, the redox properties of DA are well understood. Considerable efforts have been made in development of voltammetric methods to determine its concentration either in vivo or in vitro for several decades. − However, the direct redox reaction of DA on various bare electrodes is rather irreversible and therefore requires high overpotentials . Moreover, the direct determination of DA on a bare electrode may be interfered by other coexistence species because their redox potentials are very close, which results in low selectivity and reproducibility.…”

“…For example, ascorbic acid, whose concentration is usually much higher than that of DA, is oxidized at almost the same potential as DA on bare electrodes − Other methods, such as micellar catalysis 8 and the powder microelectrode, are also effective. All the studies have been focused on (1) improvement of electrocatalysis, (2) freedom from surface fouling, and (3) prevention of side reactions, as described elsewhere .…”

Electrochemical studies on [M(diars)2X2]+ where [X = Cl, Br; M = Os, Re, Ru, Rh; diars = o-phenylenebis (dimethylarsine)] at bare and Nafion modified electrodes

“…The analogous complexes of the radioactive isotope of Rhenium, 186 Re have been investigated with regard to their potential use in nuclear medicine [7,8]. The electrochemistry of [Re(diars) 2 Cl 2 ]Cl in glassy carbon and Nafion modified glassy carbon electrodes has been studied with the aim of the development of sensor for in vivo use [9]. Recently homoleptic iron(II) and ruthenium(II) diarsine complexes have been synthesised and their redox properties evaluated [10,11].…”

Ethanol Sensor by Using the Nickel Foil Electrode

“…Because of environmental and safety concerns, many industrialized countries have formulated laws and regulations to improve their people's health and safety. Many analytical techniques have been developed to measure the concentration of ethanol, such as titration [1], spectroscopy [2±10], electrochemical analysis [11,12], chromatography [13±17] and sensors [18±22]. Among these, sensors may be the most promising method with its simplicity, precision and convenience.…”