Sensing of Fe3+ and Cr2O72– in Water and White Light: Synthesis, Characterization, and Fluorescence Properties of a Crystalline Bismuth-1,3,5-benzenetricarboxylic Acid Framework

The problem of pollution caused by highly toxic ions has become the focus of global attention and has attracted the interest of many researchers. However, microdetection using a metal–organic framework remains a challenge. Here, we synthesized the Bi-polycarboxylate organic framework (Bi-MOF) compound [Bi(BTC)(H2O)]·H2O constructed by 1,3,5-benzenetricarboxylic acid. Structural analysis revealed that in our Bi-MOF structural unit, the adjacent codimers {Bi2O18} are further joined by C atoms in the H3BTC to form a three-dimensional organic framework. On the basis of the luminescent properties of this Bi-MOF, it could be used as a multifunctional test chemical sensor such as Fe3+ and Cr2O72–. In particular, it is found that Bi-MOF has also extremely high selectivity, sensitivity, and uniqueness for Fe3+ and Cr2O72–. When the Fe3+ concentration was 0.01 mol/L, the Ksv was 2.02 × 104 M–1, and the detection limit was 1.59 μM. When the concentration of Cr2O72– was 0.01 mol/L, the Ksv was 1.95 × 104 M–1, and the detection limit of Bi-MOF was calculated to be 1.64 μM. This was experimentally verified by analyzing the fluorescence spectrum and fluorescence lifetime. In addition, in a breakthrough of the traditional method of superimposing the three primary colors, we encapsulate Eu3+ in the blue emission center to obtain white light emission by the two primary colors first. This approach can reduce the number of variables that are difficult to control. Therefore, white light emission can be achieved by rationally doping different molar ratios of Eu3+.