Synthesis of Multifunctional Chemosensors for Naked Eye Detection of Cu²⁺ and Hg²⁺; Application in Paper Strips, Water, and Food Sample

Abstract Three chemosensors ISA‐1, ISA‐2, and ISA‐3 were synthesized for the detection of Cu 2+ and Hg 2+ ions in a 50% H₂O‐DMF solution. ISA‐1 is specifically designed for the detection of Cu 2+ ions, while ISA‐2 can detect both Cu 2 ⁺ and Hg 2 ⁺ ions. Upon interaction with Cu 2 ⁺, ISA‐1 undergoes a naked‐eye colorimetric transition from pink to blue. ISA‐2 exhibits a similar pink‐to‐blue color change in the presence of Cu 2+ ion, however, colorless when exposed to Hg 2+ ion. The detection limits for Cu 2+ using ISA‐1 and ISA‐2 are 0.574 ppm and 0.0074 ppm, respectively, both of which are significantly lower than the WHO guideline of ≤1.5 ppm for Cu 2+ in drinking water. These chemosensors have also been successfully integrated into paper strips and logic gate systems and applied for the analysis of water and food samples.