Terbium metal organic framework hollow spheres: Sensing properties for trace water in organic solvents and iron ions in water

Abstract

Terbium metal organic frameworks (Tb-MOFs) hollow spheres were synthesized by solvothermal method, using 5-aminoisophthalic acid (H2AIP) as organic ligand, 2-methylimidazole (2-MI) as competitive ligand and protective agent. Tb-MOFs exhibit excellent luminescent sensing properties to water in organic solvents, and the limit of detections (LODs) in N, N-dimethylformamide and ethanol are 0.000515% and 0.000422%, respectively. Water can not only enhance the luminescent properties of Tb-MOFs, and also a new emission peak at 418 nm (or 427 nm) appears. The enhancement and new peak are quenched by the Fe3+ in water, and the LODs of Tb-MOFs for Fe3+ at 402 nm and 545 nm are 0.45 μM and 0.71 μM, respectively. The sensing mechanism for water is water can replace part of the coordination of H2AIP with Tb3+, and the sensing mechanism for Fe3+ is that the competitive absorption between Fe3+ and H2AIP inhibits the energy absorption of the organic ligand.