[Synthesis of two different structural aromatic carboxylic acid complexes with terbium by solid state reaction at low...

Two solid complexes of terbium with phenylacetic acid (L1) and phenyl-hydroxylacetic acid (L2) were synthesized by solid state reaction at low temperature, and the complexes were characterized by chemical analysis. Elemental analysis and rare earth coordination titration studies suggested that the composition of the complexes is Tb(L1)3) x H2O and Tb(L2)3 x 4H2O respectively. IR spectra and 1H NMR studies indicated that the coordination fashion of the two ligands with Tb(III) is different The ligand (L1) is bonded with Tb(III) ions by two oxygen atoms in carboxyl group which coordinate as a symmetrical chelate bidentate group. The ligand (L2) is bonded with Tb(III) ions by one oxygen atom in carboxyl group. The molar conductivity in DMSO solvent indicates that all complexes are non-electrolyte. The fluorescence spectra of complexes and phosphorescence spectra of the ligands showed that all of the two ligands were sensitized differently by Tb3+ ions for fluorescence intensity, which indicates that the triplet state energy of ligands and the different structure of complexes play an important role in the luminescence of complexes. Fluorescence intensity of Tb(L1)3 x H2O is smaller than that of Tb(L2)3 x 4H2O. So the structure of ligand carboxylic acid has an effect on Tb3+ luminescence in these complexes.