Dual-emission Tb-based coordination polymer as a ratiometric fluorescence probe for the detection of phosphate

A simple, sensitive dual-emission probe was developed for the detection of phosphate (Pi). The probe Tb-BTB/DPA was synthesized by mixing dual-ligand, 1,3,5-tri(4-carboxyphenyl) benzene (H₃BTB) and dipicolinic acid (DPA), with metal ions Tb³⁺ in ethanol–water solution at 40℃ for 2 h. Tb-BTB/DPA exhibits two emission peaks, the emission at 362 nm is attributed to H₃BTB, an energy transfer between Tb³⁺ nodes, and DPA further enhances the fluorescence of Tb³⁺ at 544 nm. Pi competes with ligand H₃BTB to coordinate Tb³⁺, resulting in partial collapse of the Tb-BTB/DPA structure and interrupting the electron transfer between H₃BTB and Tb³⁺. Therefore, the emission at 362 nm is enhanced, while the emission at 544 nm is unchanged, and a ratiometric fluorescence method is developed to detect Pi. Tb-BTB/DPA exhibits good linearity within the Pi concentration range (0.1–50 µmol/L), and the detection limit was 25.8 nmol/L. This study provides a new way to prepare probes with dual emission sensing properties.