A Multianalyte Molecular Probe for Ultra-Sensitive Detection of Silver, Fluoride, and Cyanide Ions: Coordination Behaviour and Photophysical Insights.

A novel multianalyte molecular probe, pyrogallol aldehyde-derived semicarbazone (PSC), has been developed for the ultrasensitive and selective detection of silver (Ag⁺), fluoride (F^-), and cyanide (CN^-) ions in aqueous and DMSO media. The probe exhibits distinct coordination behavior with each analyte, leading to significant changes in its photophysical properties, including fluorescence enhancement. Spectroscopic analyses (UV-VIS and fluorescence titrations) reveal detection limits in the nanomolar range, with excellent selectivity over competing ions inducing a 50-fold fluorescence enhancement via the CHEF mechanism. The chemosensor displayed a linear response to Ag⁺ at low concentrations, achieving a detection limit of 1.36 × 10^-8 M. Upon addition of CN^-, a distinct color change from colorless to reddish-pink was observed, with a detection limit of 8.94 × 10^-8 M, and F^- ions induced a colorless-to-green transition, with a detection limit of 3.66 × 10^-7 M. Binding stoichiometry and interaction mechanisms were elucidated via Job's plot, NMR titrations, and density functional theory (DFT) calculations. This work highlights the potential of the designed probe as a powerful tool for environmental monitoring and biological applications, owing to its rapid response, high sensitivity, and multi-ion recognition capability.