Synthesis and Aggregation‐Dependent Luminescence of Cyanostilbene‐Pyridone Hybrids as Tunable Hg ² ⁺ /Ag ⁺ Chemosensors

ABSTRACT A series of novel 6‐amino‐4‐(1‐cyano‐2‐arylvinyl)‐2‐oxo‐1,2‐dihydropyridine‐3,5‐dicarbonitriles were synthesized via the reaction of functionalized 2‐chloropyridines with salicylaldoxime. These cyanostilbene‐pyridone hybrids are of significant interest as tunable fluorophores for the development of chemosensors targeting toxic heavy metal ions. The photophysical properties of compounds were studied, and structure‐specific fluorescence sensing of both mercury(II) and silver(I) ions governed by distinct aggregation mechanisms was observed. Specifically, the p ‐dimethylamino‐substituted derivative exhibited aggregation‐caused quenching (ACQ) in the presence of Hg 2 + and Ag + ions, with higher affinity for mercury(II). In contrast, the p ‐diethylamino‐substituted cyanostilbazole showed significant aggregation‐induced emission (AIE) enhancement in aqueous media. The pH‐dependence studies and interference ion screening were performed to establish optimal sensing conditions, enabling successful metal detection at sub‐micromolar levels.