Synthesis and spectra properties of europium complexes with 2-hydroxyquinoline-4-carboxylic acid

Three novel europium complexes,Eu(Hhqc)3(H2O),Eu(Hhqc)3Phen(H2O)5 and Eu(Hhqc)3TPPO(H2O)5 were synthesized using 2-Hydroxyquinoline-4-carboxylic acid(H2hqc),1,10-phenanthroline(Phen)and triphenyl phosphine oxide(TPPO)as the ligands.The complexes were characterized by elemental analysis and infrared spectrum.The IR spectra indicated that the complex Eu(Hhqc)3Phen(H2O)5 has a largerΔνthan that of NaHhqc,and carboxylate ions in the phenylglyoxyate are coordinated as monodentate ligands.TheΔνvalues of the Eu(Hhqc)3(H2O)and Eu(Hhqc)3TPPO-(H2O)5 are smaller than that of NaHhqc,the carboxylate ions coordinate to Eu3+ with bidentate chelating mode.The fluorescence properties of the complexes were studied at room temperature.Each complex shows five emission bands at 581,594,615,654 and 703nm,which are assigned to the characteristic emission 5D0→7FJ(J=0,1,2,3,4)transitions of Eu3+,respectively.The fluorescence intensity becomes stronger after the additions of Phen and TPPO,and Phen is better.