Multifunctional Lanthanide MOFs for Smartphone-Assisted Ratiometric Luminescent Sensing of Pymetrozine and Tunable Multicolor Luminescence

Lanthanide metal–organic frameworks (Ln-MOFs) possess excellent optical properties and structural diversity, offering a versatile platform for luminescence sensing and optical applications. Herein, a novel europium metal–organic framework, namely, [(CH 3 ) 2 NH 2 ] 2 ·[Eu 2 (L)(C 2 O 4 ) 2 (H 2 O) 2 ] ( Eu-MOF ), was solvothermally constructed via a rational dual-ligand strategy with 5-(phosphonomethyl)isophthalic acid (H 4 L) and oxalic acid (H 2 C 2 O 4 ) as ligands. The obtained MOF exhibits excellent water, acid–base, and thermal stability, providing a robust foundation for luminescence sensing applications. Eu-MOF served as a ratiometric luminescent sensor for the insecticide pymetrozine (PYM), exhibiting a low detection limit of 2.82 μmol L –1 with high selectivity and a distinct color change from red to dark red. Meanwhile, the sensor was successfully employed for detecting PYM in real samples (river water, apple, broccoli, and tomato) with good recoveries of 92.61–109.17%. Moreover, an integrated smartphone-based platform was developed, allowing for the precise on-site monitoring of PYM. Furthermore, in combination with the high quantum yield of Eu-MOF, a series of Eu x Tb 1– x -MOF materials ( x = 0–0.099) with tunable multicolor luminescence were prepared via doping with Tb 3+ ions. These materials exhibit multifunctionality, serving as luminescent films for decoration, color-tunable LED devices, and excitation-dependent anticounterfeiting films. This work provides a strategy for developing multifunctional Ln-MOFs with integrated ratiometric sensing capabilities and tunable luminescence properties.