Influence of solvent coordination on crystal structure and luminescent property in lanthanide MOFs

Two isomorphous Ln-MOFs with pyridine-2, 4, 6-tricarboxylic acid (H₃PTC), Eu-PTC-DMF and Tb-PTC-DMF, were prepared by solvothermal synthesis method and characterized by IR spectroscopy, and thermogravimetric analysis, and powder X-ray diffraction techniques. Single-crystal structural analyses indicate that the Ln1 and Ln2 coordination polyhedra are connected by sharing corners of polyhedra to construct 1D chain, which further form a 3D coordination framework through the connection of PTC^3- ligands, and the solvent molecules of DMF and H₂O, as the terminal ligands, are bound to polyhedra of Ln³⁺ ions. Investigation of the photophysical property at ambient conditions revealed that both Ln-MOFs emit characteristic luminescence of Ln³⁺ ions. Eu-PTC-DMF and Tb-PTC-DMF possess microsecond scale emission lifetime with absolute quantum yields as high as 33.1% and 50.8%, respectively.