A Luminescent Sensor for Trace Uranyl in Nature Water Systems Using a Terbium(III)-Organic Framework

Here, we have demonstrated a terbium(III)-organic framework ([Tb₂(H₂BTC)(BTC)(H₂O)₂]·4H₂O, denoted as 1) synthesized from 1,2,4,5-benzenetetracarboxylic acid (H₄BTC) and TbCl₃·6H₂O under hydrothermal conditions. Notably, 1 exhibits a highly efficient uranyl sensing capability in complex natural water systems such as lake water and seawater, featuring high sensitivity (K_SV = 1.13 × 10⁵ and 1.06 × 10⁵ M^-1, respectively), ultralow limit of detection (LOD = 17.47 and 18.62 nM, respectively) and excellent anti-interference ability. FTIR and XPS analyses revealed that uranyl ions coordinate with the free -COOH groups on the H₂BTC^2- ligand. Density functional theory (DFT) calculations unveiled that photoelectron transfer from H₂BTC^2- to UO₂²⁺ causes luminescence quenching of 1.