[Synthesis, characterization and fluorescence of Eu3+, Tb3+ complexes with 2-thiophencarboxylic acid and 2,2'-bipyridine].

Two binary complexes of Eu3+ and Tb3+ with 2-thiophene carboxylic acid and two ternary complexes of Eu3+ and Tb3+ with 2-thiophene carboxylic acid(L)-2, 2'-bipyridine were synthesized. By elemental analysis, rare earth coordination titration, and molar conductivities studies, the compositions of the complexes were suggested as REL3 x 2H2O and REL3L' x C2H5OH(RE=Eu, Tb, L = 2-thiophene carboxylic acid, L' = 2, 2'-bipyridine) respectively. The ligands and coordination compounds were studied by means of IR spectra, 1H NMR and fluorescence excitation and emission spectra. IR spectra and 1H NMR studies indicate that 2-thiophene carboxylic acid was bonded with RE(III) through oxygen atoms in the carboxyl group, and 2, 2'-bipyridine ligand was bonded to RE(III) through nitrogen atoms. The fluoresence spectra showed that the fluorescence emission intensity of ternary complexes was stronger than that of the binary complexes.