Multifunctional MOF-based probes for efficient detection and discrimination of Pb 2+ , Fe 3+ and Cr 2 O 7 2− /CrO 4 2

Developing metal–organic framework (MOF)-based fluorescent probes for efficient detection and discrimination of polluting ions in groundwater is vital for environmental protection and human health. In this paper, we prepared two luminescence-active transition MOFs, namely, Zn-MOF and Cd-MOF, and conducted sensing experiments. The results show that they both exhibit multiple-target detection for Fe 3+ , Pb 2+ and Cr( vi ) with high sensitivity, good anti-interference ability and good recyclability even with different frameworks. In addition, Eu 3+ -incorporated samples, Eu 3+ @MOFs, with dual-emission have been fabricated via efficient encapsulation of Eu 3+ ions into the MOF host. As expected, Eu 3+ @MOF hybrids also act as multi-target and self-calibrated probes to selectively detect Fe 3+ and Cr( vi ) ions. However, the quenching efficiencies of the original MOFs towards Fe 3+ are higher than those of Eu 3+ @MOFs. Thus, we could differentiate Fe 3+ , Pb 2+ and Cr( vi ) ions by comparing the changes of fluorescence emission between Eu 3+ @MOFs and the original MOFs. The recognition mechanism may be attributed to the competitive energy absorption between MOFs or Eu 3+ @MOFs and the analytes.