Highly Selective and Sensitive Detection of PO ₄ ^3– Ions in Aqueous Solution by a Luminescent Terbium Metal–Organic Framework

Abstract

A luminescent terbium metal–organic framework [Tb(HPIA ^–)(PIA ^2–)(H ₂O) ₂] (Tb-MOF), synthesized by a lanthanide metal ion (Tb ³⁺) and nitric heterocyclic carboxylic acid ligands H ₂PIA (H ₂PIA = 5-(1 H-pyrazol-3-yl)isophthalic-acid), was structurally characterized as a three-dimensional skeleton structure in which layered coordination frameworks are connected by hydrogen bonds. Based on the antenna effect, Tb-MOF can emit bright green fluorescence under 254 nm excitation, and the fluorescence emission presents excellent durability in aqueous solutions among a wide pH range. Moreover, the structure of Tb-MOF also possesses outstanding thermal stabilities. In some ways, PO ₄ ^3– and its derivatives are thought to be a kind of pollutant ion causing series environmental and health problems. The as-synthesized Tb-MOF exhibits prominent selectivity and remarkable sensitivity for detecting PO ₄ ^3– as an easy-to-use fluorescent probe with low detection limit, fast response, and wide detection range. Therefore, Tb-MOF has significant applications in the fields of human health and environmental monitoring.