Colorimetric probes based on organic azo dyes for selective sensing of fluoride and cyanide ions

Two novel azo dye-based probes were designed and synthesized for selective inorganic ions sensing. Chemical structure of the synthesized dyes was characterized by spectroscopic techniques. In contrast to electron donating groups (EDGs), the introduction of electron withdrawing groups (EWGs) into the backbone of the probe makes the excellent sensitivity for fluoride and cyanide ions. Interaction of the prepared probes with Fˉ and CNˉ in contrast to other anions provides remarkable colorimetric responses from yellow to blue (180 nm), enabling naked-eye sensing without any spectroscopic instrumentation. The mechanism of anion binding with probes showed one-to-one stoichiometry (Receptor: Anion) by Job’s plot