A 2D Eu‐Based Metal–Organic Framework for Detection of Rifampicin in Aqueous Solutions Through Fluorescence Quenching

ABSTRACT The synthesis and characterization of a two‐dimensional lanthanide‐based metal–organic framework, [Eu 2 (HL) 2 (H 2 O) 4 ]·5H 2 O ( 1 ), constructed using 5,5′‐(pyridazine‐3,6‐diyl)diisophthalic acid (H 4 L) as the organic ligand, are reported. Compound 1 exhibits remarkable structural stability across a broad pH range (2–12) and in various solvents, along with intense red fluorescence at 613 nm attributed to Eu 3+ ions. Notably, this work presents the first fluorescent sensor based on Ln‐MOFs for the detection of rifampicin (RIF), which operates via a fluorescence quenching mechanism. The sensor exhibits exceptional selectivity and sensitivity, achieving an ultra‐low detection limit of 0.068 μM, comparable to the most effective fluorescent sensors reported for RIF. Furthermore, 1 can be recycled up to four times, enhancing its cost‐effectiveness and sustainability. This study highlights the potential of rare‐earth MOFs in the development of advanced sensing materials for pharmaceutical applications.