A turn-on luminescence probe based on amino-functionalized metal-organic frameworks for the selective detections of Cu2+, Pb2+ and pyrophosphate.

A "turn-on" fluorescent probe based on amino-functionalized metal-organic frameworks (MOF-5-NH2) is developed for the detection of Cu2+, Pb2+ and pyrophosphate (P2O74-, PPi). The fluorescence emission of fluorescent materials obtained by one-step synthesis is attributed to organic ligands. Cu2+ and Pb2+ coordinate with the amino group on the surface of the MOF-5-NH2, which is ascribed to the host-guest electron transfer between analyte and probe, giving rise to the fluorescence quenching. After adding PPi, the intense affinity between Cu2+ and PPi remove Cu2+ from the MOF-5-NH2, blocking of the electron transfer process, and the fluorescence can be recovered. The limit of detection is 0.057, 0.25 and 0.32 μmol L-1 for the detection of Cu2+, Pb2+ and PPi, respectively. This turn-on mode based fluorescent probe shows preferable sensitivity and specificity to detect Cu2+, Pb2+ and PPi. These results demonstrate that the fluorescent MOF-5-NH2 as a sensing platform displays remarkably performance.