A europium-based MOF fluorescent probe for efficiently detecting Co2+ and CrO42−

Abstract Cobalt is an essential trace element in the human body that is vital for metabolism in living organisms. Insufficient or excessive intake of cobalt can lead to adverse effects. We prepared a europium-based metal–organic framework (Eu-MOF), NH 4 [Eu(sal) 4 (phen) 2 ] (abbreviated as Eu-sal, sal = salicylic acid group, phen = 1,10-phenanthroline). Fluorescence investigations revealed that Eu-sal can efficiently and selectively identify Co 2+ through a fluorescence quenching effect, with a quenching efficiency K SV and limit of detection (LOD) of 2.7 × 10 4 M −1 and 0.37 μ M, respectively. In addition, Eu-sal also shows highly selective for CrO 4 2 − ( K SV : 3.6 × 10 4 M −1 ; LOD: 0.27 μ M). The quenching of Eu-sal fluorescence emission by Co 2+ and CrO 4 2 − ions may be caused by spectral overlap, energy transfer, and competition. Furthermore, Eu-sal has good thermal and chemical stability. These results indicate that Eu-sal is a promising fluorescence probe for highly selective detection of Co 2+ and CrO 4 2 − ions.