Spectra Analyses of Europium Complexes with Benzoic Acid and Its Derivatives

In order to study regularity of fluorescence of complexes about rare earth with different benzoic acid,we have prepared much of BA-compiexes,RC_6H_4COOH(R=o-NH_2,H,p-NH_2,o-OH,m-Cl,o-COOH,m-COOH,p-COOH,p-OH,m-NO_2,3,5-Dinitro,p-Br,o-I,2-OH-5-SO_3H.They can be synthesized complexes with Sm~(3+),Eu~(3+),Tb~(3+),Gd~(3+).Under UV-excitation the complexes with Eu~(3+),Tb~(3+) have higher emitting(intensity) than complexes with Sm~(3+),Gd~(3+).There are some science bases about study a new luminophor.Spectra analyses of the complexes of europium with benzoic acid and its derivatives are discussed.The binary complexes of europium with benzoic acid and its derivatives(benzene carbonic acid,phthalic acid,isophthahc acid,salicylic acid,o-aminobenzoic acid sulfosalicylic acid) have been synthesized.They were characterized by(elemental) analysis,UV-Vis,IR,H NMR,fluorescence spectra and molar conductance.The UV spectra showed that the complexes' ultraviolet absorption were from the ligands(220~350 nm),so that it could transfer energy to rare earth.The measurement results of the emission spectra of the complexes indicated as follows the emission of Eu(BA)_3,Eu(m-Phth)_3·3H_2O and Eu(o-Phth)_3·3H_2O consisted of three peaks at 582,596,and 618 nm which were caused from ~5D_0→~7F_J(J=0,1,2) transition of Eu~(3+) respectively.Among these peaks the emission from ~5D_0→~7F_2 is the shrongest.But the emission of Eu o-aminobenzoic acid consisted(of three) peaks at 399,452,547 nm,and that of sulfosalicylic acid-Eu only one peak at 407 nm,which(were caused) from ligands.Fluorescence spectra show that there aren't red-characteristic emission of Eu in (Eu(o-Amino))_3 and Eu(Ssal)_3.