Sensitive and Anti-Interference Al³⁺ Sensing with a Luminescent Eu-MOF

A luminescent lanthanide metal-organic framework, [(TD)₅Eu₄(HCO₂)₂(DMF)₄] (Eu-TD, TD/H₂BTDB = 4,4'-(benzo[c][1,2,5] thiadiazole-4,7-diyl)dibenzoic acid), was synthesized via a solvothermal method by coordinating Eu³⁺ ions with the strongly emissive ligand H₂BTDB. Single-crystal X-ray diffraction analysis reveals that the Eu-TD is in the hexagonal system with space group P6₄22. Eu-TD demonstrated exceptional selectivity toward Al³⁺ ions, exhibiting remarkable sensitivity with a low detection limit (limit of detection (LOD) = 0.04 μM) and excellent anti-interference properties. Eu-TD exhibits a pronounced Al³⁺-triggered luminescent turn-on response across varied aqueous environments, underscoring its viability for environmental monitoring applications. The selective Al³⁺ recognition in Eu-TD originates from Lewis basic N sites that strongly coordinate with Al³⁺ through acid-base interactions, concurrently enhancing the absorbance and amplifying the luminescence.