A Water-Stable Hydrogen-Bonded Organic Framework (HOF) for Selective Sensing of Antibiotics in Aqueous Medium

Although metal organic frameworks (MOFs) and covalent organic frameworks (COFs) have been extensively used as fluorescent-based antibiotic sensors, newly developed hydrogen-bonded organic frameworks (HOFs) are largely unexplored toward this direction. To realize this, the luminescent HOFs must be stable in water as the analytes are mostly found in water-based effluents in environments. In addition, HOFs should be equipped with specific recognition sites in order to direct the discrimination among the antibiotics. Herein, we report a 3D porous HOF, IITKGP-HOF-6, constructed from an aromatic-rich tetratopic carboxylic acid (H₄L), which exhibits excellent hydro and prolonged open-air stability (7 and 15 days, respectively). IITKGP-HOF-6 was explored for the highly selective detection of nitrofurans (NFs) family of antibiotics in aqueous medium exhibiting a remarkably low detection limit of 0.75 μM for nitrofurazone (NFZ) through luminescence quenching. Photoinduced electron transfer driven by the presence of low-lying charge-transfer excited state below to the $$ and Forster energy transfer between H₄L donor and NFZ acceptor are confirmed to be responsible for observed quenching using detailed quantum-chemical studies. This work demonstrates the usage of HOFs as sensory materials toward antibiotics in aqueous medium along with a clear understanding into the sensing mechanism at the molecular level.