(Z)-4-oxo-4-(phenylamino)but-2-enoic acid and its solid lanthanide complexes LnL3· nH2O(Ln = La,Eu,Tb,Yb) were synthesized and characterized by means of elemental analysis, FTIR,1H NMR and13C NMR spectra. The results show that the carboxylic groups in the complexes coordinated to the lanthanide ions in the form of a bidentate ligand, but the amide carbonyl group and amino N have not taken part in the coordination. The fluorescence spectra exhibits that the Eu3 + complex display characteristic metal-centered fluorescence in solid state while Tb3 + fluorescence is completely quenched, which is attributed to being especially effectively in transferring energy from the lowest triplet energy level of the ligands onto the excited state (5D0) of Eu3 + than that (5D4) of Tb 3 +. [ABSTRACT FROM AUTHOR]