A naked-eye colorimetric sensor based on chalcone for the sequential recognition of copper(ii) and sulfide ions in semi-aqueous solution: spectroscopic and theoretical approaches

Abstract

In this study, a simple colorimetric chemosensor based on the chalcone scaffold has been employed for the sequential recognition of Cu²⁺ and S²⁻ ions in a semi-aqueous solution. The chemosensor A01 displayed chromogenic selectivity for Cu²⁺ over other metal cations and exhibited naked-eye color change from colorless to pink upon the addition of Cu²⁺. Furthermore, the A01–Cu²⁺ complex can be used for the detection of S²⁻ ions through competitive complexation of S²⁻ toward Cu²⁺. The detection limit of the chemosensor A01 for Cu²⁺ and A01–Cu²⁺ complex for S²⁻ ions is 1.3 μM and 0.4 μM, respectively, which is quite below the acceptable detection limit suggested by the WHO guidelines for drinking water. The chemosensor A01 binds reversibly to Cu²⁺, and the UV-vis changes induced by Cu²⁺ could be reverted via treatment with EDTA. To further enhance the applicability of the colorimetric chemosensor A01, the Cu²⁺ ions concentration was measured in real environmental water samples.