Hollow terbium metal–organic-framework spheres: preparation and their performance in Fe3+ detection

Hollow metal-organic framework (MOF) micro/nanostructures have been attracting a great amount of research interest in recent years. However, the synthesis of hollow metal-organic frameworks (MOFs) is a great challenge. In this paper, by using 1,3,5-benzenetricarboxylic acid (H3BTC) as the organic ligand and 2,5-thiophenedicarboxylic acid (H2TDC) as the competitive ligand and protective agent, hollow terbium MOFs (Tb-MOFs) spheres were synthesized by a one-pot solvothermal method. By comparing the morphology of Tb-MOFs in the presence and absence of H2TDC, it is found that H2TDC plays a key role in the formation of the hollow spherical structure. Single crystal analyses and element analysis confirm that H2TDC is not involved in the coordination with Tb3+. Interestingly, Tb-MOFs can be used as the luminescent probes for Fe3+ recognition in aqueous and N,N-dimethylformamide (DMF) solutions. In aqueous solution, the quenching constant (K SV) is 5.8 × 10-4 M-1, and the limit of detection (LOD) is 2.05 μM. In DMF, the K SV and LOD are 9.5 × 10-4 M-1 and 0.80 μM, respectively. The sensing mechanism is that the excitation energy absorption of Fe3+ ions reduces the energy transfer efficiency from the ligand to Tb3+ ions.