Detection of Cu(II) ion by an electrochemical sensor made of 5,17-bis(4′-nitrophenylazo)-25,26,27,28-tetrahydroxycalix[4]arene-electromodified electrode

A novel sensitive electrochemical Cu(II) ion sensor were fabricated by the electrochemical coating of functionalized calix[4]arenes with benzoyloxy or nitrophenylazo groups onto an Au electrode on a quartz crystal substrate by cyclic voltammetry (CV). The Cu(II) ion-sensing film thus prepared was characterized by scanning electron microscopy (SEM) and electrochemical impedance spectroscopy (EIS). The response current of the prepared electrochemical Cu(II) ion sensor was measured by differential pulse voltammetry (DPV). The effects of the substituent on calix[4]arene, the number of sweep cycles and the pH of the buffer solution on the Cu(II) ion sensing properties (response) of the sensors were investigated to determine the optimal conditions for detecting Cu(II) ions in water. The electrochemical Cu(II) ion sensor that was made of the calix[4]arene that was functionalized with nitrophenylazo groups exhibited a excellent response, good selectivity, acceptable linearity, a low detection limit and favorable long-term stability.