Synthesis, crystal structure and characterization of two terbium complexes with bromobenzoic acid

Two complexes of [Tb(2-BrBA)(2)(CH3COO)(2,2'-biPY)](2) (1) and [Tb(3-BrBA)(3)(2,2'-biPY)](2).2(3-HBrBA).2H(2)O (2) (2-BrBA=2-bromobenzoate, 3-BrBA=3-bromobenzoate, 2,2'-bipy=2,2'-bipyridine) were synthesized by solvent method and their structures were determined by X-ray single crystal diffraction method. Complexes 1 and 2 both belong to triclinic system and P (1) over bar space group. The complex 1 is a dimer with an inversion center, in which two different carboxylate ligands coordinate to Tb3+ ion simultaneously to form quaternary mixed-ligands complex. Four 2-BrBA ligands link the two Tb3+ ions by bidentate-bridging mode, two acetate ligands coordinate to two Tb3+ ions by bidentate-chelating mode, and two 2,2'-bipy molecules chelate to two Tb3+ ion, respectively. The ternary complex 2 is also a dimer with an inversion center, in which the two Tb3+ ions are linked by four bidentate-bridging 3-BrBA ligands and each Tb3+ ion is further bonded to one bidentate-chelating 3-BrBA ligand and one 2,2'-bipy molecule. The two complexes exhibit strong green fluorescence under ultraviolet light and the fluorescence spectrums of them both have four peaks at 489, 545, 585 and 621 nm corresponding to D-5(4) -> F-7(6), D-5(4) -> F-7(5), D-5(4) -> F-7(4) and D-5(4) -> F-7(3) transition emissions of the Tb3+, ion, respectively. CCDC: 631975, 1; 631976, 2.