Two Unusual Nanocage‐Based Ln‐MOFs with Triazole Sites: Highly Fluorescent Sensing for Fe³⁺ and Cr₂O₇²⁻, and Selective CO₂ Capture

Luminescent metal–organic frameworks (LMOFs) containing fluorescent probes for the detection of pollutants such as organic solvents and heavy metals are becoming increasingly important, with lanthanide‐MOF (Ln‐MOF) materials receiving greater attention owing to the possibility of achieving fine‐tuned luminescent properties. Herein, two unusual isostructural nanocage‐based three‐dimensional Ln‐MOFs, 1 ‐Ln (Ln=Tb, Eu), are constructed, using a new diisophthalate ligand with active Lewis basic triazole sites. Selective gas adsorption, especially the removal of CO 2 from CH 4 , a primary component of natural gas and biogas, is desirable in terms of both economic and environmental considerations. 1 ‐Eu is found to exhibit highly efficient luminescent sensing for Fe 3+ cations and Cr 2 O 7 2− anions, as well as selective CO 2 capture over CH 4 .