Dual-Functional Luminescent Sensing Properties of a 3D Rare-Earth MOF toward Hemin and Chlorophyll

In this study, a novel luminescent Eu-MOF formulated as [Eu 4 L 6 (DMA)]·2H 2 O ( 1; H 2 L = 4,4′-(ethane-1,2-diylbis(oxy))dibenzoic acid) was synthesized via the solvothermal method. SC-XRD analysis confirms that the Eu clusters in complex 1 serve as secondary building units (SBUs), which are bridged by organic linkers via carboxylate oxygen atoms to form a three-dimensional extended structure. The emission spectrum is dominated by the characteristic 5 D 0 → 7 F 2 transition of Eu 3+, peaking at 614 nm. Compound 1 functions as an efficient dual-functional sensor for Hemin and Chlorophyll (Chl) based on fluorescence quenching. It exhibits excellent sensing performance toward Hemin, with a Stern–Volmer constant ( K SV ) of 1.108 × 10 6 M –1 and an ultralow detection limit of 8.173 nM, reaching the trace level. For the detection of Chl, the sensor demonstrates a K SV of 2.748 × 10 4 M –1 and an LOD of 0.330 μM, thereby realizing rapid, sensitive, and user-friendly detection of Chl. This work not only provides a facile and efficient Eu-MOF sensor for biomolecule analysis, but also expands the application scope of MOFs in the field of fluorescence sensing.