Selective Colorimetric Sensor for the Detection of Hg ²⁺ and H ₂ S in Aqueous Medium and Waste Water Samples

Dabsyl based new colorimetric sensor 1 for the selective detection of environmentally most important cation Hg 2+ and biologically important hydrogen sulfide (H 2 S) in aqueous medium have been reported. The probe 1 selectively responded to Hg 2+ among various cations and shows colour change from yellow to red with the bathochromic shift in Uv‐Vis spectrum via intramolecular charge transfer (ICT) mechanism. The limit of detection for mercury was determined as 80 μM. The possibility of using 1 to detect mercury in industrial waste water samples was also explored with good recovery value. The ensemble 1.Hg 2+ , also applicable for the detection of H 2 S (LOD = 28 μM) in water among different bio‐thiols and anions. H 2 S displaces the mercury from 1.Hg 2+ via metal displacement approach and regenerates the original probe 1 within few seconds. Regenerated receptor 1 , further used for the detection of mercury ion. Receptor 1 incorporated test paper and polymer based thin films were used as a portable kit for the selective colorimetric detection of mercury and H 2 S in water.