Lanthanide-Functionalized Metal−Organic Framework as Ratiometric Probe for Selective Detection of 4-NA and Fe3+

Luminescent MOFs with dual or multiple emission centers can act as multi-target and self-calibrating probes to selectively detect environment pollutants with high precision. In this paper, we synthesized Ln3+@Zn-MOF (Ln3+ = Eu3+ and Tb3+) with dual emission characteristics by post-encapsulation Ln3+ ions into Zn-MOF. The fluorescence sensing experiments show that Eu3+@Zn-MOF can be used as a multi-functional and self-calibrating probe to selectively detect 4-nitroaniline (4-NA) and Fe3+ ions with high sensitivity, good anti-interference and repeatability. The LOD is 6.01 μM and 60.99 μM for 4-NA and Fe3+ ions, respectively. Compared to the pristine Zn-MOF, Eu3+@Zn-MOF exhibits the higher sensitivity and accuracy in detection application. Further studies on UV–vis adsorption spectra show that the possible fluorescence quenching mechanism are the competitive absorption of excitation light between MOF and the analytes. And this work presents a promising strategy to prepare dual emissions probes for effective detection of environment pollutants.