A europium MOF-based turn-off fluorescent sensor for Cr2O72−, L-tryptophan, Dimethylnidazole detection in water

Various pollutants in water are a serious threat to human health. It is very important to identify and detect harmful substances in water. In this paper, an unprecedented new coordination polymer of luminescent sensor, [[Eu(L)2] Cl·H2O] n, (Eu-MOF), with excellent fluorescence sensing abilities for anions, amino acid and antibiotics was developed. It was synthesized by N-heterocyclic carboxylic acid ligands 1, 3-bis (4-carboxylbenzyl) triazole chloride and lanthanide metal ion Eu3+ under solvothermal conditions. The fluorescence results indicate that Eu-MOF has excellent fluorescence sensing abilities for Cr2O72−, l-tryptophan, and Dimethylnidazole via fluorescence quenching. The limit of detection (LOD) is 8.98 × 10−6 mol·L−1, 4.94 × 10−5 mol·L−1 and 5.50 × 10−5 mol·L−1, respectively. Furthermore, the possible mechanisms of fluorescence quenching in the sensing process were systematically studied by UV–vis and DFT. It is revealed that the rational design and utilization of such one multifunctional Eu-MOF can offer guidance for fluorescence detection with wide applications.