Rare Earth Halogenated Benzoic Acid Complexes Synthesis, Crystal Structure And Performance

Eighteen ternary complexes of Eu(III) and Tb(â…¢), six quaternary complexes of Eu(III) and Tb(â…¢) mixed with NO3-, eight quaternary complexes of Eu(III) and Tb(â…¢) doped with Y(III) or Gd(III) have been synthesized. In these complexes, nine halogen-benzoic acids were used as the first ligand, and 1,10-phenanthroline as the second neutral ligand. The compositions of these complexes were confirmed by elemental analysis (C, H, N) and EDTA titration for rare earth.The complexes were characterized by means of IR, UV, TG-DTG and SEM methods. In these complexes, the Eu(III) and Tb(â…¢)ions were bonded to the oxygen atoms of carboxylate and the nitrogen atoms of neutral ligands. These complexes show good thermal stability. The structures of three ternary complexes Eu(p-FBA)3phen·H2O (1), Tb(o-FBA)3phen (2) and Tb(p-FBA)3phen (3) have been determined using X-ray diffraction. They exist as binuclear molecules, 1 and 3 crystallize in triclinic, space group P1. 2 crystallize in monoclinic, space group P2(1)/c. The crystallographic parameters are as follows: (1) a = 8.3682(7) (?), b = 12.7584(11) (?), c = 14.9215(13) (?);α= 96.7310(10) (?),β=103.0540(10) (?),γ= 78.7890(10) (?); (2) a = 19.9178(13) (?), b = 15.1536(10) (?), c = 20.5664(14) (?);α= 90 (?),β=109.8590(10) (?),γ= 90 (?). (3) a = 9.8875(10) (?), b = 11.7744(12) (?), c = 14.7646(16) (?);α= 111.9060(10) (?),β= 101.5230(10) (?),γ= 101.5830(10) (?).The luminescence spectra of the complexes show that the characteristic emission peaks of Eu(III) and Tb(III) remain unchanged. However, the emission intensity of the complexes changes due to the different ligands or different doped metal ions. The major works in this paper are focused on: (i) the influence of different substituents on the luminescent intensity; (ii) the best luminescent complex is figured out in each series; (â…²) cultivate single crystals to explain the relationship of the structure with the luminescence; (â…³) the influence of NO₃^- on the luminescent intensity; (v) the influence of the doped rare earth ions on the luminescent intensity. These results will provide valuable information for the synthesis of new effective rare earth luminescent materials.