Metformin-integrated luminescent hydrogen-bonded organic framework for rapid and selective fluorescent detection of hypochlorite.

Hypochlorite (ClO-), a widely used oxidant in disinfection and bleaching processes, requires rapid and reliable analytical detection because of its strong reactivity and widespread use. Herein, a metformin-integrated terbium-doped hydrogen-bonded organic framework (Tb@PMA-MET) was developed as a luminescent sensing platform that integrates molecular recognition with lanthanide luminescent transduction. The integrated metformin units provide electron-rich guanidine sites for selective hypochlorite recognition, while Tb3+ serves as the emissive center through the antenna effect. The sensor exhibited a rapid response within 10.3 s, high sensitivity with a detection limit of 104 ng mL-1, and a broad linear range of 0.1-100 μg mL-1. In addition, enhanced Stern-Volmer quenching behavior was observed for Tb@PMA-MET compared with the Tb@PMA reference material. Fluorescence lifetime measurements, PXRD, FT-IR, XPS, and density functional theory calculations collectively suggested that hypochlorite preferentially interacts with metformin units, accompanied by chemical transformation and excited-state deactivation. The sensing platform was further validated by spike-and-recovery analysis in diluted bleach and tap water matrices. This work demonstrates the potential of metformin-integrated luminescent HOFs as fluorescent sensing platforms for rapid hypochlorite analysis in representative aqueous matrices.