A luminescent Eu(III)-MOF for selective sensing of Ag+ in aqueous solution

A 3D open structure FeIII(OH)[C6H2(CO2)2(CO2H)2]·xH2O(MIL-82) with carboxyl-rich groups is designed as a parent metal-organic framework (MOF). A stable lanthanide fluorescent MOF was successfully constructed by doping the Eu3+ cation on the coordination site of MIL-82. The intense luminescence of Eu3+ incorporated MIL-82 indicates that uncoordinated carboxyl group is an efficient framework for accommodating and sensitizing Eu3+ cations. The luminescent MOF can be developed as a chemical sensor for Ag+ in aqueous solution. The sensor also displays high selectivity towards Ag+, excellent sensitivity with a relatively low detection limit (0.09 μM) and fast response time within 3 min. In addition, the framework has excellent water stability and thermal stability, which provides a rare method for detecting Ag in daily water samples.