[Synthesis and fluorescence properties of the complexes [(Tb(x)Y(1-x)) (HL)L'Cl x 1/2H2O]]

By replacing a part of terbium ions with yttrium ions using doping method, a series of dinuclear complexes of 1,3,5-benzene tricarboxylic acid (H3BTC) and phenanthroline (phen) with different molar ratios of Tb3+ to Y3+ were synthesized in the present paper. Their elemental analysis, rare earth complexometric titration, molar conductivity, IR spectra and UV spectra were studied, and the contents of terbium and yttrium of three doped complexes were measured by a plasma emission spectrophotometer. Their chemical formula is inferred to be (Tb(x)Y(1-x)) (HL)L'Cl x 1/2H2O (x = 0.10, 0.30, 0.50, 0.70, 0.90, L = BTC3-, L' = phen). The infrared spectra and ultraviolet spectra were determined, the results showed that the rare earth ions are bounded with the oxygen atoms of trimesic acid, and with the nitrogen atoms of phenanthroline. The fluorescence spectra of the complexes were determined at the room temperature (the exit and entrance slits are both 1.5 nm). The fluorescence intensity of terbium doped yttrium complexes is stronger than those of the terbium complex; it was showed that the fluorescence intensity of Tb3+ ion is greatly enhanced by Y3+ ion in the complexes. The fluorescence intensity of (Tb0.7 Y0.3)(HL)L'C1 x 1/2H2O complex is the strongest among the six complexes. The lowest excitation state energy level of Tb3+ ion and the triplet state energy level of the ligands (H3BTC and phen) match well each other, and the absorbing energy of the ligands is effectively transferred to Tb3+ ion.