Ion-Transfer Voltammetry at a Water/1,2-Dichloroethane Interface Using Photoionization by Ultraviolet Irradiation: Detection of Cation Radicals of p-Phenylenediamine Derivatives

Abstract

We have attempted to detect electrically neutral substances by ion-transfer voltammetry at an interface between two immiscible electrolyte solutions (ITIES), such as an interface between water and 1,2-dichloroethane (a W/DCE interface), by irradiating the interface with ultraviolet light (200 - 300 nm). In the present work, while considering the facts that p-phenylenediamine derivatives are soluble in DCE, but insoluble in water, and that cation radicals of the derivatives are fairly stable in various media, we photoionized the derivatives in a DCE phase by ultraviolet irradiation, and after that carried out ion-transfer voltammetry at a W/DCE interface. As a result, we could successfully observe ion-transfer waves of cation radicals of the derivatives from the W to DCE phase. Namely, the cation radicals are generated in the DCE phase by ultraviolet irradiation, and subsequently distributed into the W phase. In addition to these ion-transfer waves, we also found that facilitated proton-transfer waves by the derivatives were shifted to a more negative potential region after ultraviolet irradiation, because of hydrogen chloride formed from photodecomposition of DCE by ultraviolet irradiation.

Interface between Two Immiscible Electrolyte Solutions Electrodes for Chemical Analysis

“…An interface between two immiscible electrolyte solutions (ITIES) is a unique electrode, capable of detecting a wide range of electroactive chemical species regardless of their classification as redox-active or redox-inactive. − ITIES electrodes have become more prevalent in analytical science due to their sensitivity beyond redox-active analytes and their ease of fabrication down to the nanoscale, , allowing for high spatial resolution which enables single-entity and nanostructure studies. − Electrochemistry at the ITIES has enabled researchers to probe fundamental mechanistic processes ,,− and a wide range of applications, including catalysis, − cellular studies, − ,,,,− heavy metal detection, − pharmacological studies, ,− …”