Missing-linker engineering of Eu (III)-doped UiO-MOF for enhanced detection of heavy metal ions

The creation of defects into luminescent MOFs allows for manipulation of fluorescent properties and thus leads to the enhanced detection performance for technological applications. Herein, a modulator-induced defect formation strategy was proposed to introduce missing-linker defect into lanthanide-based metal–organic framework (Eu@UiO-MOFs) and the enhanced detection properties was investigated. Notably, the missing-linker numbers in per Zr 6 cluster were calculated to facilitate comparison and quantitively interpretation. By elaborately tailoring defect numbers, the resultant Eu@UiO-MOFs-2 sensor with 0.53 missing linkers per Zr-O cluster showed a remarkably enhanced response slope and realized excellent trace detection under the range of 0–10 ppm with ultralow detection limit to 5.67 × 10 −7 M (114 ppb), acting as a powerful signal amplifier for trace detection of Cd 2+ . Moreover, the relationship between structural change and defect numbers of Eu@UiO-MOFs-X has been studied to understand the positive effect of the improved enrichment for the optical behavior. As far as we know, this is the first experimental demonstration of missing-linker defects in luminescent MOFs for regulation of optical sensing, offering a unique approach to explore innovative technologies for precisely detecting of heavy metal ion pollutants.