A luminescent lanthanide MOF for selectively and ultra-high sensitively detecting Pb2+ ions in aqueous solution

Abstract

A luminescent lanthanide metal–organic framework [Tb(L)(H₂O)₅]_n solvents (Tb-MOF, H₂L⁻ = 3,5-dicarboxyphenol anion ligand) with a 2D network structure was synthesized. The size of the Tb-MOF single crystal can reach up to 6 mm; such large-scale single crystals of MOFs are rarely reported in the literature. Tb-MOF exhibits a strong green luminescence induced by the efficient antenna effect of the ligands. Importantly, it shows an excellent recognition ability on detecting the Pb²⁺ ion, which is a noxious inorganic pollutant and causes permanent damage to human health and living environments. The perfect linear correlation between the luminescence intensity of Tb-MOF and the concentration of the Pb²⁺ ions provides this crystal as a reliable and easy-to-use luminescent sensor, which can be applied in pollutant monitoring. As far as we know, it is the first example of a high-efficiency luminescent MOF sensor with millimeter level for detecting Pb²⁺ ions at a very low concentration with a detection limit down to 10⁻⁷ M.