A Coordinative Postsynthetic Modification Coupling Ion-Imprinted Strategy for Improving the Hydrothermal Stability and Selectivity of Tb-MOF

Lanthanide-based metal–organic frameworks (Ln-MOFs) have received wide attention as luminescent sensors due to their outstanding porosity and optical properties. However, the poor selectivity and instability of Ln-MOFs in a water environment limit their application in a complex sample matrix. To address this issue, a luminescent Tb–H4btc-Asp@IIP was developed through amino acid functionalization via a coordinative postsynthetic method (CPSM) combined with surface imprinting strategies. The synthesized Tb–H4btc-Asp@IIP retained 90.2% of its original fluorescence intensity after 30 days in aqueous environments and exhibited high thermal stability up to 286 °C. This improved stability was primarily attributed to a protective ion-imprinted polymer (IIP) layer measuring 90 nm in thickness. Additionally, Tb–H4btc-Asp@IIP exhibited excellent selectivity for Pb(II), benefiting from the dual recognition capabilities of the Asp functional groups and the imprinted cavity for Pb(II). The Tb–H4btc-Asp@IIP sensor effectively detected Pb(II) concentrations ranging from 5 to 300 ng/mL, achieving a low detection limit of 3.19 ng/mL. In vegetable samples, the sensor was able to quickly detect Pb(II) levels, with the average recovery ranging from 82.4 to 109.2% and RSD values of 2.0%–4.8%. The photoinduced electron-transfer (PET) effect and dynamic quenching process contributed to the sensing process of Tb–H4btc-Asp@IIP.