Tb-MOF: a naked-eye and regenerable fluorescent probe for selective and quantitative detection of Fe3+ and Al3+ ions

Sensitivity and selection for metal ion detection are of crucial importance in protecting human health. Using 4,4',4 ''-tricarboxytriphenylamine (H(3)TCA) as the ligand, a unique terbium based metal-organic framework (Tb-MOF), [Tb-3(TCA)(2)(DMA)(0.5)(OH)(3)(H2O)(0.5)]center dot 3H(2)O (1), has been prepared, structurally identified and further employed as a fluorescent probe for selective and quantitative detection of metal ions. Compound 1 selectively detects Fe3+ and Al3+ through fluorescence quenching effects at 549 nm and fluorescence enhancement at 463 nm, respectively, from among 19 types of metal ions without interference. Most notably, compound 1 exhibits a clearly visible color change in the presence of Fe3+ from yellow to deep brown, with a detection limit of 8 x 10(-6) M. As a fluorescent probe for Al3+, 1 can be simply and quickly regenerated. Its detection limit of 7 x 10(-7) M is significantly lower than the highest limit of Al3+ in drinking water recommended by the WHO (7.41 mu M), representing a rare example in reported fluorescent sensors for Al3+. Tb-MOF 1 is an example of a fluorescent probe that features naked-eye detection, regeneration, high selectivity and quantitative detection of Fe3+ and Al3+ ions.