Two isomorphic rare earth coordination polymer based on 1-imidazol-1-yl-2,4,6-phenyltricarboxylic acid ligand: Synthesis, structure, fluorescence sensing and practical applications

Abstract

Two three-dimensional metal organic framework {[Ln2 (ttc)3]∙1.5 DMF}n{Ln3+=Tb3+(1), Sm3+(2)} was synthesized by solvothermal reaction of rare earth metal Ln3+ ions and 1-imidazol-1-yl-2,4,6-benzene-tricarboxylic acid (H3ttc). The crystal characteristics and composition of the two compounds were confirmed by powder X-ray diffraction (PXRD) and thermogravimetric analysis (TG), and the single crystal X-ray diffraction confirmed that they are isomorphic. The luminescence and sensing properties of the two compounds were investigated in detail, the Tb-MOF exhibits characteristic emission of Tb3+ through effective sensitization by antenna effect and emits bright green fluorescence under excitation light of 254 nm. Fluorescence experiments show that Tb-MOF has high selectivity and sensitivity for the detection of TNP, Cr2O72−, and Al3+ with the limit of detection of 2.89×10−8 mol·L−1, 2.35×10−8 mol·L−1 and 2.69×10−8 mol·L−1, respectively. In addition, possible luminescence quenching mechanisms are discussed. As a result, such a Tb-MOF will be a promising candidate and applies to the field of fluorescent ink and fingerprint retrieval.