Anion sensors containing imidazole and anthraquinone derivatives

Abstract

An anthraquinone derivative containing imidazolium salt L1 was synthesized and then covalently attached to the surface of multi-walled carbon nanotubes. Complexation studies of the modified nanotubes supported on glassy carbon electrodes with anions including F-, Cl-, Br-, I-, and H₂PO₄- and amino acids, such as glycine, D-alanine, D-leucine, D-phenylalanine and D-tryptophan were carried out by cyclic voltammetry. However, no changes in CV were observed. Conversely, the prepared electrodes showed promising electrocatalytic activities for hydrazine oxidation. The catalytic behavior of the reaction between L1 modified nanotubes acting as a mediator and hydrazine was analyzed by cyclic voltammetry in pH 7.0 buffer solution (HEPES + NaCl). It was found that the catalytic currents proportionally increased to the concentration of hydrazine, leading to calibration plots for the determination of hydrazine. The modified electrode as a hydrazine sensor exhibited the detection limit 1.01 µM obtaining from the linear range over hydrazine concentration 0.0-10.0 µM. Herein, we proposed the mechanism of the electrocatalytic oxidation of hydrazine at glassy carbon electrodes functionalized with L1/MWNTs.