An Adenine‐Based Chromone‐Coupled ‘Off‐On‐Off’ Fluorogenic Dyad for Cascade Detection of Zn 2+ and HSO₄ − Ions or Zn 2+ Ions and Picric Acid

A chromone‐coupled adenine‐based fluorogenic chemosensor ( BD1 ) has been introduced for cascade detection of Zn 2+ and HSO 4 − ions or Zn 2+ and picric acid (PA) based on the fluorescence ‘OFF‐ON‐OFF’ mechanism. A momentous fluorescence improvement has been observed due to the accumulation of Zn 2+ ions in the BD1 solution because of the formation of the Zn 2+ chelated BD1 complex. A cyan color fluorescence enhancement is visible under the exposure of a 365 nm UV lamp, which is also manifested in the CIE diagram. The detection limit of our developed sensor BD1 and Zn 2+ − BD1 complex towards the identification of Zn 2+ and HSO 4 − ions are in the nM and μM range, respectively, in the solution phase. Among the several explosive nitroaromatic compounds (NACs), only PA quenches the fluorescence of the Zn 2+ chelated BD1 complex, and the nature of quenching is both static and dynamic. A paper strips‐based test kit experiment is performed for on‐spot identification of Zn 2+ ions and PA. Based on these chemically encoded inputs and the fluorescence intensity as optical output, we have constructed an INHIBIT molecular logic circuit. The present report evokes a new approach for the development of new chemosensors from bioinspired materials such as adenine, a purine nucleobase.