3D water stable Eu(III)-organic framework as recyclable multi-responsive luminescent sensor for efficient detection of lead ion, permanganate anion and para-nitrophenol in aqueous medium

Abstract

Using a mixed ligand strategy a novel 3D Eu(III) metal–organic framework with tetranuclear SBUs formulated as [Eu2(NTA)2(Ada)(DMF)2] (Cj-1) was solvothermally synthesized by employing 2-nitroterepthalic acid (NTA) as antenna and adipic acid (Ada) as bridging spacer. Multiple coordination modes and bright fluorescence characteristics make Cj-1 ideal as fluorescent probe. Fluorescence studies reveal that Cj-1 emits intense red luminescence and displays excellent water stability and outstanding chemical stability over broad pH range (pH = 2–10). The Cj-1 exhibits strong luminous sensing response against inorganic ions Pb2+, MnO4−, and para-nitrophenol in water with high sensitivity, selectivity, rapid reaction and an outstanding recycle usage. It is interesting to note that the solid sample's color changes from white to brown upon detection of the MnO4− ions. This color change signifies luminescence induction, making the method for detecting MnO4− ions simple and more practical to everyday life. Powder X-ray diffraction, infrared spectroscopy, elemental analysis, and luminescence methods were used to characterize the compound. The potential sensing mechanisms of Cj-1for selective sensing have been thoroughly investigated.