Synthesis, crystal structure and fluorescence of a new europium complex with 2-bromobenzoate and 2,2′-bipyridine

A new complex of {[Eu2(2-BrBA)6(2,2′-bpy)2]2·CH3CH2OH·H2O} (2-BrBA=2-bromobenzoate; 2,2′-bpy=2,2′-bipyridine) was prepared by solvent method and characterized with X-ray single-crystal diffraction, IR spectroscopy, UV spectroscopy, and fluorescence spectroscopy. The complex crystallized in triclinic crystal system, Pī space group, with a=1.17196(4) nm, b=2.36142(9) nm, c=2.59151(9) nm, α=113.266(2)°, β=101.100(2)°, and γ=94.400(2)°. Two independent dinuclear molecules were contained in the asymmetric unit. The two molecules were similar to each other. Each Eu(III) ion was nine-coordinated with seven oxygen atoms from five 2-BrBA ligands and two nitrogen atoms from 2,2′-bpy molecule. The carboxylate groups acted as bidentate-chelating, bidentate-bridging and chelating-bridging coordination modes. The complex adopted a distorted monocapped square-antiprism coordination geometry. Five peaks at 579, 591, 613, 652, and 697 nm appeared in the fluorescence spectrum, corresponding to 5D0→7F0, 5D0→7F1, 5D0→7F2, 5D0→7F3, and 5D0→7F4 transition emissions of the Eu(III) ion, respectively.