Terbium-based dual-ligand metal organic framework by diffusion method for selective and sensitive detection of danofloxacin in aqueous medium

A water-dispersible Tb(III)-based metal organic framework (TBP) was produced by diffusion technique using benzene-1,3,5-tricarboxylic acid (BTC) and pyridine as easily accessible ligands at low cost. The as-synthesized TBP with a crystalline structure and rod-shaped morphology has exhibited thermal stability up to 465 °C. Elemental analysis confirmed the presence of carbon, oxygen, nitrogen, and terbium in the synthesized MOF. TBP was used as a fluorescent probe for detection of danofloxacin (DANO) in an aqueous medium with significant enhancement of fluorescence intensity as compared to various fluoroquinolone antibiotics (levofloxacin (LEVO), ofloxacin (OFLO), norfloxacin (NOR), and ciprofloxacin (CIPRO)) with a low detection limit of 0.45 ng/mL (1.25 nm). The developed method has successfully detected DANO rapidly (i.e., response time = 1 min) with remarkable recovery (97.66-101.96%) and a relative standard deviation (RSD) of less than 2.2%. Additionally, TBP showcased good reusability up to three cycles without any significant performance decline. The in-depth mechanistic studies of the density functional theory (DFT) calculations and mode of action revealed that hydrogen bonding interactions and photo-induced electron transfer (PET) are the major factors for the turn-on enhancement behavior of TBP towards DANO. Thus, the present work provides the quick and precise identification of DANO using a new fluorescent MOF (TBP) synthesized via a unique and facile diffusion technique.