Simple naked-eye colorimetric chemosensors based on Schiff-base for selective sensing of cyanide and fluoride ions
The present work describes the design and synthesis of simple colorimetric chemosensors based on Schiff-base for highly selective sensing of cyanide and fluoride ions. The chemosensor S2, containing an electron withdrawing group (EWG), displayed selective sensing properties for both cyanide and fluoride ions. The interaction of S2 with F– and CN– ions provides remarkable colorimetric responses from yellow to purple, enabling naked-eye sensing without any spectroscopic instrumentation. The mechanism of anion binding with chemosensor S2 showed one-to-one stoichiometry by Job’s plot. The mechanism of interaction between the S2 and CN– ions has been confirmed by the 1H NMR titration experiments. Furthermore, the detection limits of chemosensor S2 towards F– and CN– ions were found to be 3.7 and 1.2 μmol/L, respectively.