A water-stable Y(III)-MOF as multi-responsive luminescent sensor for high-efficiency detection of Fe3+, Cu2+, and MnO4- ions in aqueous solutions

Abstract

The effective detection of pollutants in water, such as Fe3+, Cu2+, and MnO4- ions, is critical to human health and environmental protection. Two yttrium-based coordination polymers {[Y(BITA)(H2O)]NO3}n (CP-1) and {[Y(HBTA)(ox)(H2O)]·H2O}n (CP-2) based on a π-conjugated 2,5-di(1H-imidazol-1-yl)terephthalic acid (H2BITA) were successfully prepared and sufficiently characterized. CP-1 exhibits a unique cationic 3D framework with a lvt net, accompanied by the decoration of NO3- anions. Adjacent Y3+ sites are bridged by double syn-syn carboxylate to form [Y2(μ-COO)2]n chains. CP-2 shows a 3D two-fold interpenetrating network with zigzag chains of [Y2(μ-C2O2)]n formed by ancillary oxalate bridging Y3+ ions. The HBTA- linkers propagate the 1D oxalate chains into 3D frameworks. The luminescent properties of CPs were investigated. Both CPs-1 and 2 exhibit purple and green fluorescence in the solid state, respectively. Meanwhile, CP-1 demonstrates excellent luminescent emission together with good chemical stability. Intriguingly, CP-1 exhibits outstanding selective and sensitive detection of cationic Fe3+ and Cu2+ and anionic MnO4- in aqueous solutions through luminescence quenching. In particular, the luminescence intensity could be significantly decreased by existence of MnO4-, which is seldom reported among the Y(III)-based coordination polymers. The quenching mechanism for various ions has been discussed in detail.