A highly selective and sensitive quinoline-based fluorescent turn-off chemosensor for the detection of picric acid

A simple turn-off quinoline-based fluorescent chemosensor, 1-(6-amino-2-methyl-4-phenylquinolin-3-yl)ethan-1one ( QN ) has been developed, synthesized, and characterized by various spectroscopic methods. This probe is selective for the sequential recognition of picric acid (PA), using a fluorescent turn-off method. QN exhibits a broad emission band at 504 nm, but fluorescence quenching occurs upon the addition of picric acid over other nitro compounds. The binding stoichiometric ratio between QN and picric acid was calculated to be 1:1 through Job 's plot analysis, and the binding constant was determined. The limit of detection towards picric acid was found to be 9.33 mu M. Further, the mechanistic approach for binding has been investigated by spectroscopic methods like 1 H NMR titration, FT-IR studies, and density functional theory (DFT) studies.