Reflectance chemosensor based on bis-thiourea derivative as ionophore for copper(II) ion detection

Abstract

A reagentless, rapid and facile optical reflectance sensor has been fabricated based on immobilization of novel bis-thiourea (BT) ligand compound, N,N′-(((3,3′-dimethoxy-[1,1′-biphenyl]-4,4′-diyl)bis(azanediyl))bis(carbonothioyl))bis(4-methoxybenzamide) onto acrylic poly(n-butyl acrylate) [poly(nBA)] microspheres for sensitive and selective determination of Cu2+ ion in aqueous solution. Binding study of BT ionophore toward Cu2+ ions was performed via colorimetric detection and UV–Vis titration experiments. The stoichiometric binding ratio and binding constant (Ka) of BT to Cu2+ ion was determined to be 1:2 and 5.2 × 104 M−1, respectively, based upon Job's plot and Benesi–Hildebrand analyses. The optical reflectance chemosensor based on BT derivative element responded exclusively to Cu2+ ion while being almost irresponsive to the other interfering ions, and exhibited a dynamic linear response range from 7.80 × 10−7–1.60 × 10−4 M Cu2+ ion with a limit of detection (LOD) of 6.12 × 10−7 M, and fast response time of <1 min. The developed reflectometric Cu2+ ion-selective sensor yielded promising reversibility and reproducibility performance with the respective RSD values of 2.3% and 2.6%, which signifies highly reproducible fabrication technique of the Cu2+ ion sensor. Real sample application of the proposed optical sensor provided excellent results of Cu2+ ion concentration detection in river water samples, which were in good agreement with those obtained by ICP-OES standard method.