[Study on photoluminescence of 2-(4-chloro-benzoyl)benzoic acid complexes]

Eight complexes of europium and terbium were synthesized, with 2-(4-chloro-benzoyl)benzoic acid as an essential ligand and other three distinct ligands, including 1, 10-phenanthroline, triphenylphosphine oxide and diphenyl sulfoxide, as selective ligands. They were Eu(CBBA)3 (H2O)4, Eu(CBBA)3 (Phen) (H2O)6, Eu(CBBA)3 (TPPO) (H2O)4, Eu(CBBA)3 (DPSO) (H2O)5, Tb(CBBA)3 (H2O)4, Tb(CBBA)3 (Phen)(H2O)3, Tb(CBBA)3(TPPO)(H2O)2 and Tb(CBBA)3 (DPSO)(H2O)4, respectively. Then their excitation and emission spectra were measured, and that how the central ions were differently impacted by the three second ligands was also compared. It was easily to be seen that from the spectra all the complexes luminesced with the similar special peaks. However, the luminescence intensity was evidently distinct, because 1, 10-phenanthroline, triphenylphosphine oxide and diphenyl sulfoxide were coordinated with them, and exerted different effects on transferring energy to the central ions. In the complexes of europium, Eu(CBBA) (Phen) (H2O) 6 and Eu(CBBA) (DPSO) (H2O) 5 each luminesced more strongly than Eu(CBBA)3 (H2O)4, however, Eu(CBBA)3(TPPO) (H2O)4 luminesced more weakly than Eu(CBBA)3 (H2O)4. Moreover, Eu(CBBA) (DPSO)(H2O)5 luminesced more intensely than Eu(CBBA)3 (Phen)(H2O)6. So 1,10-phenanthroline and diphenyl sulfoxide could sensitize the luminescence, whereas triphenylphosphine oxide could quench the luminescence in the certain Eu complexes. In Tb complexes, diphenyl sulfoxide sensitized the luminescence of Tb(CBBA)3 (DPSO)(H2O)4, and reversely, 1,10-phenanthroline and triphenylphosphine oxide quenched differently the luminescence of Tb(CBBA)3 (Phen)(H2O)3 and Tb(CBBA) (TPPO)(H2O)2. 1,10-phenanthroline quenched more strongly than triphenylphosphine. From IR spectra, the structure of the complexes was conjectured approximately. In the region of 3 200-3 600 cm(-1), there were some weak vibrant peaks owed to hydroxyl of water, a good proof that there were water molecules in the complexes themselves.