Camphoric acid and 2,5-bis(pyrid-4-yl)pyridine laden Cd(II)-coordination polymer as reversible turn-off-on sensor for...

Coordination polymers (CPs) represent versatile platforms for the design of luminescent sensors owing to their structural tunability and photophysical properties. In this work, a cadmium(II)-based CP with the formula [Cd(BPYP)(CPA)·0.5DMF·H₂O] (1) is synthesized via a solvothermal route and comprehensively characterized. The rigid bicyclic-camphoric acid imparts structural robustness, while 2,5-bis(pyrid-4-yl)pyridine promotes extended π-conjugation and directional connectivity, leading to high framework stability and pronounced photoluminescent behavior. The material functions as a selective fluorescent probe for glutamate (glu), exhibiting a LOD of 7.44 × 10^-4 M and strong tolerance against interference from other biomolecules. The quenching response arises from a synergistic interplay of static quenching, resonance energy transfer, and photo-induced electron transfer, governed by favorable orbital overlap between glutamate and the excited framework. Remarkably, luminescence is restored in the glu@1 system upon addition of salicylic acid, attributable to competitive displacement of bound glutamate.