A novel resonance fluorescence chemosensor based on the formation of heterobinuclear complex with a di-tetradentate macrocyclic ligand and europium (III) for the determination of uranium (VI)

In this paper, we synthesized and characterized a di-tetradentate macrocyclic ligand as a novel resonance fluorescence probe for the determination of uranium. The ligand contains two tetradentate ligand moieties and can chelate two cations to form binuclear complex. We found that when the ligand only chelates a uranyl ion or europium (III) ion, the formed complex can only produce weak resonance fluorescence. When the ligand chelates simultaneously uranyl and europium (III) to form heterobinuclear complex, the formed complex can produce strong resonance fluorescence due to the cation-cation interaction between uranyl and europium (III). Based on this finding, we established a resonance fluorescence chemosensor for the determination of uranium (VI) by utilizing the formation of the heterobinuclear complex. Under optimal conditions, the linear range for the determination of uranium (VI) is 0.008-1.2 nmol mL−1 with a detection limit of 0.002 nmol mL−1. The method has been applied to determine uranium (VI) in environmental water samples with the recoveries between 95.7% and 103.6%.