Novel synthesized azo-benzylidene-thiourea as dual naked-eye chemosensor for selective detection of Hg2+ and CN- ions

Seven novel chemosensors contain azo chromophore and phenylthiourea, were synthesized and applied as colorimetric probes in aqueous solutions of dimethyl sulfoxide. The anion recognition studies exhibited that the synthesized azo dye derivatives act as a highly dual-sensitive and selective chromogenic sensor for naked-eye detection of Hg2+ and CN- ions, with a different color change from yellow to colorless and yellow to red, respectively. The limit of detection (LOD) was found for 3c toward Hg2+ and CN- ions to be 4.89 mu M and 2.23 mu M, respectively. The result of the Job's plot indicating that the stoichiometry binding ratios of compound 3c to Hg2+ is 1:1 and to CN- is 1:2. These results were confirmed by H-1 NMR titration experiments.