A water-stable europium-MOF as a multifunctional luminescent sensor for some trivalent metal ions (Fe, Cr, Al), PO ions, and nitroaromatic explosives.

A luminescent Eu-MOF, namely, [Eu(ppda)(npdc)(HO)]·HO (1) based on the mixed ligands 4-(pyridin-3-yloxy)-phthalic acid (Hppda) and naphthalene-1,4-dicarboxylic acid (Hnpdc) was synthesized under solvothermal conditions. Compound 1 was initially constructed from the 1D binuclear chains of [Ln(npdc)] and further connected by ppda ligands, forming a 2D layered structure. It is worth noting that compound 1 exhibited excellent fluorescence stability in the pH range of 2-13 in an aqueous solution. It was found that compound 1 could not only detect trivalent Fe, Cr and Al ions with high selectivity and recyclability but also serve as an excellent selective sensing material for PO ions among some anions. The detection of NACs demonstrated that compound 1 could also behave as a functional probe with high selectivity, sensitivity, and recyclability, and the detection limit of TNP was 2.97 × 10 M. Furthermore, the luminescent sensing mechanisms for different analytes were speculated.