Synthesis, Characterization And Luminescence Properties Of Lanthanide Complexes With 2-Pyrazinecarboxylic Acid And Succinic Acid

Sixteen solid lanthanide complexes with 2-pyrazinecarboxylic acid (Hpyca) and succinic acid (BDAH) were synthesized and characterazied by elemental, IR, UV, EDTA titrition, ICP, and TG-DTA analyses. Elemental analysis, EDTA titration and TG-DTA studies show that the complexes have the compositions of Eu(Pyca)3·8H2O,Tb(Pyca)3·8H2O,Eu(Pyca) (BDA)·2H2O,Tb(Pyca) (BDA)·2H2O,Eu0.5Y0.5(Pyca)3·9H2O, Eu0.5La0.5(Pyca)3·8H2O,Eu0.5Gd0.5(Pyca)3·9H2O,Tb0.5Y0.5(Pyca)3·9H2O, Tb0.5La0.5(Pyca)3·7H2O,Tb0.5Gd0.5(Pyca)3·6H2O,Eu0.5Y0.5(Pyca) (BDA)·3H2O,Eu0.5La0.5(Pyca) (BDA)·4H2O,Eu0.5Gd0.5(Pyca) (BDA)·3H2O,Tb0.5Y0.5(Pyca) (BDA)·3H2O,Tb0.5La0.5(Pyca) (BDA)·3H2O and Tb0.5Gd0.5(Pyca) (BDA)·3H2O. IR spectra and UV spectra indicate that the lanthanide ions coordinated with the carboxylic oxygen atoms of 2-pyrazinecarboxylic acid (Hpyca) and succinic acid (BDAH).Luminescence spectra indicate that the complexes can emit characteristic fluorescence from rare earth ion (Eu3+,Tb3+). The triplet state energy level of 2-pyrazinecarboxylic acid (24000cm-1) is higher than the main emitting states of Eu3+ (17210cm-1) and Tb3+(20430cm-1). So the efficiency of ligand-to-metal energy transfer in terbium complexes would be better than in europium complexes. The doped La3+,Y3+,Gd3+ don't influence the fluorescence peak position, but increased remarkably luminescent intensity of lanthanide complexes. Luminescence spectra indicate that two ligands (2-pyrazinecarboxylic acid and succinic acid) in complexes can more effectively transfer the absorbed energy to the center lanthanide ions. Fluorescence lifetime and relative quantum efficiency of these lanthanide complexes can also indicate that the doped La3+,Y3+,Gd3+ could increase the efficiency of ligand-to-metal energy transfer.