A naked-eye chemosensor for simultaneous detection of iron and copper ions and its copper complex for colorimetric/fluorescent sensing of cyanide

A new prototype of multifunctional chemosensor 1 has been synthesized for Fe^2+/3+, Cu²⁺ and CN^- in aqueous solution. This sensor could simultaneously detect biologically important metal ions (iron and copper) through colorimetric methods over most other competitive cations. The detection limit (2.9 μM) of 1 for Cu²⁺ is lower than WHO guideline (31.5 μM) in drinking water. Interestingly, the resulting 1-Cu²⁺ complex sensed cyanide in colorimetric and fluorometric ways, showing recovery from 1-Cu²⁺ to 1, over other common interference anions. These results demonstrate a novel type of versatile chemosensor for multiple target ions using two different sensing methods, simple colorimetric and sequential detections.