Facile colorimetric sensing of Pb2Â + using bimetallic lanthanide metal-organic frameworks as luminescent probe for field screen analysis of lead-polluted environmental water

A new colorimetric sensor for Pb2 + based on bimetallic (Eu-Tb) lanthanide (Ln) metal-organic frameworks (MOFs) was developed for field screen analysis of lead-polluted environmental water. The Ln-MOFs were prepared by using a simple and fast synthetic method, with Tb3 +/Eu3 + and 1,4-benzenedicarboxylate (BDC) as precursors. The color of the luminescent Ln-MOFs could be fine-tuned from green to red by doping the MOFs with different ratios of Tb3 +/Eu3 +, and a specific MOFs Tb1.7Eu0.3(BDC)3·(H2O)4 was synthesized and employed as the sensing probe. With the existence of Pb2 + in an appropriate concentration range with a certain amount of Tb1.7Eu0.3(BDC)3·(H2O)4, the emission color of the MOFs changed from red-orange to green, which could be visually observed by the naked eyes. This colorimetric sensing method turned out to be simple, rapid, cost-effective and highly selective, without any requirement for complicated instrumentation. Furthermore, lead-polluted environmental water samples were analyzed for Pb2 +, illustrating the promising perspective of the developed method for field screen analysis.