Gold electrodes functionalized by methyl-naphthyl substituted cyclam films for the detection of metal ions

Abstract A methyl-naphthyl functionalized cyclam (1,4,8,11-tetraazacyclotetradecane) (N-MNC) was deposited on gold electrodes and characterized by means of infrared spectroscopy in ATR mode, wettability, morphology and an electrochemical study. The proton conductivity of the N-MNC film was brought out, for the first time, by electrochemical impedance spectroscopy (EIS) and by cyclic voltammetry (CV); the anodic peaks located at 0.15 V and at 0.45–0.50 V, due to proton exchange, were shown to increase when electrolyte pH decreases. The chemical sensor based on an n-MNC functionalized gold electrode was studied in the presence of divalent (Cu 2+ , Ni 2+ , Zn 2+ ) and trivalent (Fe 3+ ) metallic ions. The influence of the metallic ion concentration on the ion-exchange resistance of the film and on the proton-exchange anodic peak was quantified. The highest sensitivity was obtained for Ni 2+ and Fe 3+ , with a detection limit of 10 −8  M.