A ratiometric luminescence probe based on lanthanide metal–organic framework@polyethyleneimine for sensitive and selective detection of Cu2+ and Fe3+

The development of probes for the detection of multiple heavy metal ions holds the nonnegligible practical significance for ensuring public and environment safety. In this work, a ratiometric luminescence probe was proposed for the detection Cu2+ and Fe3+ based lanthanide metal–organic framework@polyethyleneimine (Ln-MOF@PEI). The formation of the complexes between PEI and Cu2+ enhances the quenching efficiency of MOF through a combination of inner filter effect and energy transfer, surpassing the observed quenching efficiency with Fe3+. The emission intensity ratio between Tb3+ and the ligands exhibits a decreasing trend with increasing Cu2+ concentration, while it rises with increasing Fe3+ concentration. It allows for the discrimination between Cu2+ and Fe3+ based on their distinct quenching mechanisms. The assay performance of Ln-MOF@PEI probes was evaluated comprehensively. The limit of detection for Cu2+ and Fe3+ reaches at 9.7 nM and 37.4 nM, respectively. The probe demonstrates acceptable selectivity by effectively avoiding interference from common cations and anions. The detection range covers a wide concentration range from nanomoles to millimoles. Overall, the luminescence probe is expected to meet the requirements of accurate quantification for Cu2+ and Fe3+ in the various application scenarios.