[Synthesis and fluorescence characteristics of Eu-TB complexes with trimesic acid]

A series of mixed rare earth complexes Eu(1-x)Tb(x) (BTC) x nH2O(H3BTC=1,3,5-H3BTC, x = 0.1, 0.3, 0.5, 0.7, 0.9, 1.0) were synthesized by the reaction of trivalent rare earth chlorides with trimesic acid. The contents of rare earth were mearsured by using EDTA titration method, the element analyses of C and H were performed by Vario EL elemental analyzer. Their infrared spectra were recorded by FTIR-8900 infrared spectrophotometer with KBr pellet, and the fluorescence spectra were recorded by using a Hitachi F-4500 fluorescence spectrophotometer at room temperature. These results show that these complexes Eu(1-x) Tb(x) (BTC) x nH2O can emit intense fluorescence from europium ion, the intensity of the fluorescence of the series complexes is greater in (5)D0-->7F(1,2), and both the positions ((5)D0-->7F(1,2)) show splitting emission peaks, but the peak positions of their emission spectra basically remain unchanged. These may be caused by the different coordinating pattern of the carboxylate groups. Additionally, the fluorescence intensity of europium ions was sensitized by terbium ions and that of terbium ions was quenched by europium ions. in these complexes. It was attributed to efficient energy transfer from the strongly absorbing ligand to the rather poorly absorbing lanthanide ion. and from Tb3+ to Eu3+. Moreover, the fluorescence emission of terbium ions increased markedly in these complexes.