Spectroelectrochemical Sensing Based on Multimode Selectivity Simultaneously Achievable in a Single Device. 13. Detection of Aqueous Iron by in Situ Complexation with 2,2‘-Bipyridine

Abstract

A spectroelectrochemical sensor with attenuated total reflectance at an indium-doped tin oxide (ITO) optically transparent electrode coated with a thin film of Nafion has been demonstrated for the determination of aqueous iron ion. The novelty of this sensor stems from its ability to take up colorless iron ion (Fe2+) from solution and complex it with an organic ligand, 2,2'-bipyridine (bipy), that has been previously loaded in the optically transparent charge-selective Nafion film coating the electrode. The resulting complex ion, tris(2,2'-bipyridyl)iron(II), Fe(bipy)3(2+), absorbs strongly, making it easily detectable via optical spectroscopy. Fe(bipy)3(2+) loaded into the selective film is oxidized to colorless Fe(bipy)3(3+), which gives rise to an absorbance change for quantifying iron. This paper maps the development of this sensor, from the spectroelectrochemical characterization of the complex ion at an ITO optically transparent electrode to an analysis of the uptake, retention, and optical response of the complex ion in the Nafion film. Finally, an evaluation of the uptake of aqueous Fe2+ by the bipy-loaded Nafion film is reported. These data include preliminary results illustrating the dependence of the sensor response on differing concentrations of Fe2+ in solution.

Electrochemistry and Spectroelectrochemistry of Luminescent Europium Complexes

“…It is therefore necessary to select ligands that not only have the appropriate energetics to sensitize Eu fluorescence but also are electrochemically inactive in the potential range of interest [4,18]. To satisfy electrochemical needs, 2,2'-bipyridine (bpy) and bpy derivatives were chosen as the focus of this work [18].…”

“…It is therefore necessary to select ligands that not only have the appropriate energetics to sensitize Eu fluorescence but also are electrochemically inactive in the potential range of interest [4,18]. To satisfy electrochemical needs, 2,2'-bipyridine (bpy) and bpy derivatives were chosen as the focus of this work [18]. Additionally, significant spectroscopic characterization has been completed on Eu complexes with bpy and many bpy derivatives, which have been shown to successfully sensitize Eu fluorescence [19,20].…”

Dual-nanomaterial based electrode for voltammetric stripping of trace Fe(II) in coastal waters

“…S5a, the peak current was low when the accumulation potential was set to 0 V, indicating the Fe(II)-Bp complex can be adsorbed on the surface without the attract of negatively charged electrode which may owing to Nafion film would adsorb positively charged cation ions-ligand complex in acidic solution [24]. The peak current was increased when the potential varied from 0 to À 0.1 V and then decreased in the potential range of À 0.1 to À 0.4 V due to the complex might be too strongly adsorbed on the negatively charged surface.…”

Polymer‐coated Boron Doped Diamond Optically Transparent Electrodes for Spectroelectrochemical Sensors

“…Spectroelectrochemical sensing offers unique advantages, including three modes of selectivity: spectroscopy, electrochemistry, and selective partitioning [6][7][8]. To be detected, analytes must partition into a charge selective film.…”

“…To be detected, analytes must partition into a charge selective film. Within this film, the analyte must electrochemically oxidize or reduce at a certain potential and absorb or fluoresce in the oxidized or reduced form [5][6][7][8]. Many different electrode materials suffice for spectroelectrochemical measurements, however, optically transparent electrodes (OTEs) such as indium tin oxide (ITO), and gold minigrids are amongst the most commonly used [9,10].…”