A Zn-Based Fluorescent Coordination Polymer as Bifunctional Sensor: Sensitive and Selective Aqueous-Phase Detection of Picric Acid and Heavy Metal Ion

In contrast to the traditionally exploited cages, organic chromophores and metal organic frameworks (MOFs) as a sensing model, the chemistry of 1D coordination polymers as promising sensors is still under explored and needs special attention. Herein, a zinc 1D coordination polymer, {[Zn(HPydc)₂]·2H₂O}_n (1) has been synthesized using 2,3-Pyridinedicarboxylic acid (H₂Pydc) and characterized employing FT-IR, single crystal X-ray, PXRD, TG, CV, spectral studies, time resolved fluorescence and Hirshfeld surface analysis. The 1 displayed intermolecular O⋯H, Cl⋯H and others interactions, which create a supramolecular network. These interactions have been substantiated by Hirshfeld surface analyses. 1 exhibit promising dual functional sensing behaviour for recognition of picric acid (PA) and Pd²⁺ ions over other nitroaromatic compounds (NACs) and metal ions via fluorescence quenching with high selectivity and sensitivity in the aqueous phase. The unique properties of 1 as a potential bi-functional chemosensor for the detection of both PA and Pd²⁺ in the aqueous medium has been estabilished as confirmed by its high quenching efficiency, selectivity and superior detection limit. The sensing mechanism is explored by spectral titrations, time decay and also by the DFT (B3LYP/def2-SVP) studies. The present investigation adds to the advancement of MOF or CP materials research, particularly in their application as biological and environmental fluorescent chemosensors.