Water‐Stable Lanthanide Coordination Polymers with Triple Luminescent Centers for Tunable Emission and Efficient Self‐Calibration Sensing Wastewater Pollutants

Abstract Conventional luminescent sensors relying on single emission responsive to analytes demonstrate limited sensitivity and selectivity and developing novel self‐calibration probes is highly required. A series of water‐stable coordination polymers (CPs) with three emitting centers for tunable emissions is reported. They are facilely synthesized by simultaneously doping red‐emitting Eu³⁺ and green‐emitting Tb³⁺ into the same framework. The versatile Eu_0.67Tb_0.33–CP is applied to conveniently distinguishing different nitroaromatics pollutants and multidimensional ratiometric sensing CrO₄²⁻/Cr₂O₇²⁻. Specific nitroaromatics can cause unique changes to the ligand→Eu³⁺/Tb³⁺ energy transfer efficiency, while CrO₄²⁻/Cr₂O₇²⁻ intriguingly quench the three emissions at different rates. Each nitroaromatic exhibits notably correlation to a unique combination of the two ligand→Eu³⁺/Tb³⁺ emission intensity ratios, enabling a 2D fingerprint recognition. Furthermore, the concentration‐dependent evolution of the two ratios upon exposure to CrO₄²⁻/Cr₂O₇²⁻ can be mapped out, achieving a 3D code recognition. As a result, the sensor demonstrates selective recognition of 4‐nitrophenol and CrO₄²⁻/Cr₂O₇²⁻ with high sensitivity and selectivity as well as great recycling ability. Both the synthetic and sensing strategies present a promising strategy to develop facile and effective ratiometric sensors.