Selective and recyclable tandem sensing of PO and Al by a water-stable terbium-based metal-organic framework.

Herein, a luminescent water-stable terbium-based metal-organic framework (MOF) {Tb(Cmdcp)(HO)·5HO} (1, HCmdcpBr = N-carboxymethyl-(3,5-dicarboxyl)pyridinium bromide) has been synthesized and used for the recyclable sensing of PO and Al in tandem. MOF 1 acts as a fluorescent sensor for PO by the luminescence "turn-off" mechanism with high selectivity over other anions, such as F, Cl, Br, I, NO, HPO, HSO, HCO, HSO, SO, CO and HPO. The formed PO@1 complex further acts as the Al sensor with the luminescence "turn-on" mechanism, also with high selectivity over diverse inorganic cations of Fe, Mn, Co, Ni, Hg, Na, K, Li, Ag, Mg, Ca, Cd, Pb, Cu, and Zn. The detection process for both PO and Al can be directly observed with naked eyes under the UV light at 365 nm. The detection limits for PO and Al are 1.1 μM and 6.6 μM, respectively. Such a sensing cycle is further transferable to urine and serum samples with a satisfactory near-quantitative recovery, highlighting its good potential in biologically relevant applications.