A water stable Eu(<scp>iii</scp>)–organic framework as a recyclable multi-responsive luminescent sensor for efficient detection of <i>p</i>-aminophenol in simulated urine, and Mn^VII and Cr^VI anions in aqueous solutions

A novel 3D Eu(iii) metal-organic framework (Eu-MOF-1) formulated as [Eu(L)(H2O)(DMA)] (L = 2-(2-nitro-4-carboxylphenyl)terephthalic acid) has been successfully synthesized under solvothermal conditions and characterized by structural analyses. Eu-MOF-1 displays a new 3D framework containing EuIII ions, ligand L, and coordinated DMA molecules and water molecules. The fluorescence investigations indicate that Eu-MOF-1 emits bright red luminescence, and shows relatively high water stability and outstanding chemical stability under a relatively wide range of pH conditions. It is noteworthy that Eu-MOF-1 can quantitatively detect p-aminophenol (PAP) which is a metabolite of phenylamine in human urine. More significantly, Eu-MOF-1 is the first reported multi-responsive luminescent sensor for detecting the biomarker PAP, and MnVII and CrVI anions with high selectivity, sensitivity, recyclability and relatively low detection limits in aqueous solutions. Furthermore, the possible sensing mechanisms of Eu-MOF-1 for selective sensing have also been explored in detail. Eu-MOF-1 could be an ideal candidate as a multi-responsive luminescent sensor in biological and environmental areas.