A simple fluorophore-imine ensemble for colorimetric and fluorescent detection of CN- and HS- in aqueous solution.

Colorimetric and fluorescent detection of cyanide and hydrogen sulfide ions has been effected using a simple organic probe in H₂O:DMSO (20:80, v/v) medium. The probe exhibits a colour change from pale-yellow to red upon addition of these analytes under normal light and fluorescent change from green to red under UV lamp. Other competitive ions show no observable colour or fluorescence change. The binding constants of cyanide and hydrogen sulfide ions with the probe determined using fluorescence titration data are found to be 2.1 × 10⁴ and 1.6 × 10⁴ M^-1, respectively. The probe fluorimetrically detects the analytes in a wide pH range (4-10). ¹H and ¹³C NMR studies suggest that the probe senses cyanide ion through deprotonation and nucleophilic addition mechanism and hydrogen sulfide ion via deprotonation mechanism. Detection limits of cyanide and hydrogen sulfide are determined to be 0.15 and 1 μM, respectively. The practical utility of the probe has been demonstrated by same dual mode detection of cyanide in food materials like bitter almond, cassava flour and sprouting potato.