A La-MOF as multi-responsive fluorescence sensor for Fe3+, PO43− and p‑Nitroaniline with high sensitivity and selectivity

Excessive emissions of Fe3+, PO43−, and p-Nitroaniline in the environment pose a major threat to human health and the earth ecology. Hence, a rapid and effective detection method for these pollutants is urgently needed. Here, three kinds of three-dimensional porous lanthanide metal-organic frame materials (Ln-MOFs) have been synthesized by hydrothermal method, namely {[Ln3(NTB)3(bib)0.5(H2O)2]•nH2O}n [H3NTB = Nitrilotrisbenzoic acid, bib = 1,4-bis(1-Imidazoly)benzene, Ln = La(Ⅰ), Ce(Ⅱ), Pr(Ⅲ)]. By single crystal X-ray diffraction analysis, Ⅰ-Ⅲ are homogeneous compounds with monoclinic crystal system and P21/c space group. Peculiarly, La-MOF (Ⅰ) is an excellent multi-response luminescence sensor, which can simultaneously detect Fe3+, PO43− and p-Nitroaniline (LOD values are 1.29 × 10−6 M, 1.59 × 10−6 M, 1.32 × 10−6 M, respectively) with high selectivity, low detection limit and good anti-interference ability. It is a rare multifunctional fluorescence sensor for Fe3+, PO43− and p-Nitroaniline. In addition, La-MOF (I) has excellent chemical and thermal stability, and it can be stable in aqueous solutions with pH = 2-12 and below 240℃, which indicates that La-MOF (I) has the potential to be applied in practical complex environments. The possible mechanisms in the fluorescence sensing process are explored by X-ray powder diffraction (PXRD), X-ray photoelectron spectroscopy (XPS), UV-vis spectroscopy and density functional theory (DFT).