Hollow terbium metal–organic-framework spheres: preparation and their performance in Fe(3+) 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 (H(3)BTC) as the organic ligand and 2,5-thiophenedicarboxylic acid (H(2)TDC) 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 H(2)TDC, it is found that H(2)TDC plays a key role in the formation of the hollow spherical structure. Single crystal analyses and element analysis confirm that H(2)TDC is not involved in the coordination with Tb(3+). Interestingly, Tb-MOFs can be used as the luminescent probes for Fe(3+) 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 Fe(3+) ions reduces the energy transfer efficiency from the ligand to Tb(3+) ions.