Dual-Responsive Benzo-Hemicyanine-Based Fluorescent Probe for Detection of Cyanide and Hydrogen Sulfide: Real-Time Application in Identification of Food Spoilage.

Colorimetric and fluorescent probes have received a lot of attention for detecting lethal analytes in realistic systems and in living things. Herein, a dual-approachable Benzo-hemicyaninebased red-emitting fluorescent probe PBiSMe, for distinct and instantaneous detection of CN - and HS - was synthesized. The PBiSMe emitted red fluorescence (570 nm) can switch to turn-off (570 nm) and blue fluorescence (465 nm) in response to CN - and HS - , respectively. Other nucleophilic reagents, such as reactive sulfur species (RSS) and anions, have no contact or interference with the probe; instead, a unique approach is undertaken to exclusively interact with CN - and HS - over a wide pH range. The measured detection limits for CN - (0.43 μM) and HS - (0.22 μM) ions are lower than the World Health Organization's (WHO) recommended levels in drinking water. We confirmed 1:1 stoichiometry ratio using Job's plot and observed good quantum yield for both analytes. The probe-coated paper strips were used to detect the H 2 S gas produced by food spoilage (such as eggs, raw meat, and fish) via an eye-catching visual response. Moreover, fluorescence bioimaging studies of living cells was done to confirm the probe's potential by monitoring the presence of CN - and HS - in a living system.