Study on the Potential of Copper(II)Tetraaza Complex as Ionophore for Detecting Iodide Ion

Abstract

Selective detection of toxic anions is important in developing colorimetric chemical sensors. Copper(II)tetraaza (CuT) complex is used for the first time as an ionophore in detecting iodide anions. The anion detection studies include colorimetric studies, binding studies using ultraviolet-visible spectroscopy (ULBN), and Density Functional Theory (DFT) calculation. Visible color changes occurred when the CuT complex was added to the iodide (I-), thiocyanate (SCN-), and cyanate (CN-) anion from purple to yellow or pink. The binding constant, Kb values for I-, SCN-, and CN- anions were 160.7, 27.1, and 21.6 M-1, respectively, demonstrating the strongest binding interaction towards Ianion. The binding mode ratio between CuT and anions (I-, SCN-, CN-) is 1:2 from the equilibrium graph. Interference studies show CuT has a higher selectivity towards the I- anion. DFT calculations showed that poly(n-butyl acrylate), [poly(nBA)] is suitable to be used as a solid support for CuT complex. A lower binding energy (binding) value of -1613.424673 eV for CuT complex [immobilized with poly(nBA)] with I- anion compared to CuT complex with I- anion alone of -1567.056909 eV indicates the formation of strong bond between CuT complex [immobilized with poly(nBA)] with I- anion. An optical sensor can be fabricated on CuT complex as an ionophore and immobilized using poly(nBA) to develop an I- ion sensor.