Metal‐Free γ,δ ‐Unsaturated β ‐Ketothiolester: Solvatochromism, AIEE and Detection of Picric Acid

A synthesis of γ,δ ‐unsaturated β ‐ketothiolester depend on the properties of solvent and their relative humidity. γ,δ ‐unsaturated β ‐ketothiolester shows solvent dependent emission due to excited state intramolecular proton transfer (ESIPT). Increasing solvent polarity makes larger Stokes’ shifts ranging from 4072 to 6459 cm −1 . γ , δ ‐unsaturated β ‐ketothiolester exhibit red‐shifted emission (591 nm) in the solid state than the solution. In THF‐H 2 O mixture, solvent polarity parameter (Δ f ) increases by increasing H 2 O ratio (0‐90%) where aggregation‐induced emission enhancement (AIEE) of γ,δ ‐unsaturated β ‐ketothiolester enhanced by increasing Δ f . The Intermolecular interaction by polar protic solvent with γ,δ ‐unsaturated β ‐ketothiolester is the response for decrease in emission above 60% H 2 O in THF‐H 2 O mixture. Picric acid detection of γ,δ ‐unsaturated β ‐ketothiolester enhanced by AIEE with a detection limit of 2  μ M. Emission quenching mechanism was identified using NMR technique. Selective detection of picric acid is high when with compared to other nitroaromatic compounds and act as a inexpensive test strip detector for picric acid.