A lanthanide coordination polymer as a ratiometric fluorescent probe for rapid and visual sensing of phosphate based on the target-triggered competitive effect

Abstract

Developing novel luminescent materials for sensitive and rapid detection of phosphate (Pi) is vital in clinical diagnoses and water-quality monitoring. Herein, a lanthanide coordination polymer (NH₂-BDC–TbGMP CPs)-based ratiometric fluorescent probe is designed for quick and visual detection of Pi. The NH₂-BDC–TbGMP CPs are prepared via the self-assembly of 2-aminoterephthalic acid (NH₂-BDC) and guanine monophosphate (GMP) with terbium ions (Tb³⁺). After the formation of NH₂-BDC–TbGMP CPs, the inherent fluorescence of NH₂-BDC is quenched via static quenching, while the nonluminous Tb³⁺ can emit strong green fluorescence due to the antenna effect between Tb³⁺ and GMP. In the presence of Pi, Pi can competitively combine with Tb³⁺ to interrupt the interaction of the NH₂-BDC–TbGMP CP system, further causing a decrease in the fluorescence of Tb³⁺ and an increase in the emission of NH₂-BDC. Accordingly, the ratiometric fluorescence sensing of Pi can be achieved by continuously recording the variations of two fluorescence signals. The corresponding fluorescence intensity ratio of Tb³⁺ to NH₂-BDC (F₅₄₇/F₄₂₅) is linearly correlated with the Pi concentration in the range of 0.5 to 100 μM, with a detection limit of 0.13 μM. This strategy offers a simple, rapid, and sensitive method for the ratiometric fluorescence and visual sensing of Pi, which shows great application potential for water-quality monitoring.