A ratiometric fluorescent probe based on a dual-ligand lanthanide metal–organic framework (MOF) for sensitive detection of aluminium and fluoride ions in river and tap water

Abstract

In this study, a ratiometric fluorescent probe towards Al³⁺ and F⁻ using a lanthanide metal–organic framework material, Eu-BDC-NH₂/TDA, is employed, which is composed of a metal centre Eu³⁺, BDC-NH₂ and a TDA dual ligand. This three-dimensional frame structure selectively detects Al³⁺ and F⁻ with a low limit of detection of 0.14 and 0.46 μM, respectively, accompanied by a naked-eye identification specificity in the range of 0–1000 μM. The detection mechanism of Eu-BDC-NH₂/TDA towards Al³⁺ is due to the collapse of the framework and coordination interaction between Al³⁺ and the ligand, and that towards F⁻ is due to a hydrogen-bond interaction, as evidenced by powder X-ray diffraction, Fourier-transform infrared spectroscopy, X-ray photoelectron spectroscopy and N₂ adsorption–desorption analysis. Furthermore, practical application of Eu-BDC-NH₂/TDA is successful for the detection of Al³⁺ and F⁻ in river and tap water samples.