Fast and selective detection of Cu ²⁺ by a novel chromone‐based colorimetric chemosensor

A novel colorimetric chemosensor, DCMB (2,4‐dichloro‐N′‐((4‐oxo‐4 H ‐chromen‐3‐yl) methylene) benzohydrazide), was designed to detect Cu 2+ . DCMB exhibited a rapid and highly selective colorimetric response to Cu 2+ , changing from colorless to yellowish green with negligible interference from other metal ions. The limit of detection of DCMB for Cu 2+ was 1.19 μM, and the chemosensor remained effective for Cu 2+ detection across pH 4–10. These features showed the potential of DCMB as a convenient indicator for Cu 2+ monitoring. In environmental water samples such as tap, drinking, stream, and seawater, DCMB reliably recognized Cu 2+ with good recovery. Additionally, DCMB ‐coated test strips enabled on‐site detection of Cu 2+ , and a DCMB ‐based smartphone application offered a portable and practical quantification of Cu 2+ . The detection mechanism of DCMB for Cu 2+ was proposed to be a 1:1 binding reaction by Job plot, ESI‐MS, 1 H NMR titration, and DFT calculations.