Lanthanide(III)-Modified MIL-125(Ti-Ln) (Ln = Eu or Tb) for the Detection of Cu(II) and Fe(III) Ions

Heavy metal pollution has become a worldwide concern of environmental problems. The replacement of partial Ti(IV) centers with Eu(III) or Tb(III) yielded a couple of lanthanide(III)-modified MIL-125(Ti) materials, MIL-125(Ti-Ln) [Ln = Eu(III) or Tb(III)]. MIL-125(Ti-Ln) series were explored as fluorescent probes toward a series of metal ions based on the fluorescence properties of lanthanide(III) centers. Heterometallic MIL-125(Ti-Ln) series exhibited highly selective fluorescence quenching responses toward Cu(II) and Fe(III) ions. Moreover, the possible mechanism of fluorescence quenching was also studied.