Synthesis of Three Different Structural Aromatic Carboxylic Acid Complexes with Europium with Solid State Reaction at Low Temperature and Studies on Luminescence Property

Three solid complexes of europium with 1-naphthoic acid(L1),benzoic acid(L2) and phenylacetic acid(L3) have been synthesized by method of solid state reaction at low temperature.Elemental analysis,rare earth coordination titration studies suggest that the compositions of the complexes are Eu(L1)3,Eu(L2)3·1.5H2O,Eu(L3)3·1.5H2O respectively.IR spectra and 1HNMR studies indicated that the coordination fashion of three ligands with Eu(Ⅲ) is different.The ligand(L1) is bonded with Eu(Ⅲ) by two oxygen atoms in carboxyl group which coordinate as an asymmetrical bridging bidentate group.The ligand(L2) is bonded with Eu(Ⅲ) by two oxygen atoms in carboxyl group which coordinate as a chelate-bridging tridentate group.The ligand(L3) is bonded with RE(Ⅲ) by two oxygen atoms in carboxyl group which coordinate as a symmetrical chelate bidentate group.The Molar conductivity in DMSO solvent indicates that all complexes are nonelectrolyte.Fluorescence spectra of complexes and phosphorescence spectra of ligands show that all of three ligands have sensitized differently Eu3+ in fluorescence intensity.It indicates that the triplet state energy of ligands and the different structure play an important role in luminescence of complexes.Fluorescence intensity of three complexes is Eu(L1)3Eu(L2)3·1.5H2OEu(L3)3·1.5H2O.So structure of carboxylic acid has an effect on Eu3+ luminescence in this complexes.