A reversible dual mode chemodosimeter for the detection of cyanide ions in natural sources

Herein, we report the synthesis of two indolium probes 1 and 2 based on anthracene and pyrene derivatives and their interactions with various anions. Of these probes, the pyrene conjugate 2 acts as a dual colorimetric and fluorescent chemodosimeter for the selective and sensitive detection of cyanide ions. The detection limit of probe 2 for CN(-) ions was found to be 10 ppb (30 nM). The nature of interaction has been thoroughly studied through various techniques such as (1)H NMR and IR spectroscopy, HRMS, and isothermal calorimetric (ITC) studies. These studies confirm that probe 2 forms a 1,2-adduct in the presence of CN(-) ions. Kinetic studies using probe 2 showed the completion of the reaction within 15 s with a rate constant of k' = 0.522±0.063 s(-1). This probe can be coated on a solid surface (dipstick) and a polymer matrix for the on-site analysis and quantification of endogenous cyanide ions in natural sources such as Indian almonds.