Three Lanthanide Coordination Polymers Based on Novel Rigid Tetracarboxylate Ligand： Syntheses, Crystal Structures, and Luminescence Properties

Three lanthanide coordination polymers [Ln(bcpb)0.5(NO3)(DEF)2] (Ln = Y (1), Tb (2), Eu (3), H4bcpb = 2,5-bis(2,4-dicarboxyphenyl) pyridine and DEF = N,N-diethylformamide)) have been solvothermally synthesized under hydrothermal conditions with a novel H4bcpb ligand and trivalent lanthanide nitrates. Single-crystal X-ray diffraction analysis reveals that compounds 1~3 are isostructural and crystallize in the monoclinic system, space group P21/n. Crystal data for 1: C20H26N4O9Y, Mr = 555.36, a = 13.022(9), b = 17.778(12), c = 10.861(8) A, β = 100.208(3), V = 2475(3) A, Z = 4; Crystal data for 2: C20H26N4O9Tb, Mr = 625.37, a = 13.0476(4), b = 17.8037(7), c = 10.9398(3) A, β = 100.008(4), V = 2496.4(12) A, Z = 4; Crystal data for 3: C20H26N4O9Eu, Mr = 618.41, a = 13.055(4), b = 17.833(5), c = 10.893(3) A, β = 100.133(4), V = 2496.4(12) A, Z = 4. The compounds were characterized by thermogravimetric analysis (TGA), IR spectroscopy, and X-ray single-crystal diffraction. Compounds 1~3 all feature 2D networks with -ABABfashions. The luminescent properties of compounds 1~3 and free H4bcpb ligand were investigated at room temperature. The results show that the H4bcpb ligand can efficiently transfer energy to the Tb(III) ions, while the energy is not fully transferred from the H4bcpb ligand to the Eu(III) ions.