[Synthesis and spectral characterization of rare earth complexes of acylpyrazolone-beta-alanine].

ABSTRACT

In non-aqueous solvent, a new amino-acid schiff base, 1-phenyl-3-methyl-4-benzoyl pyrazolone-5-beta-alanine (HL) was synthesized by a reaction of beta-alanine with benzoylpyrazolone, and its ten rare earth complexes were obtained from refluxing a solution of schiff base and rare earth nitrates. On the basis of elemental analysis and molar conductance, the general formula of the complexes, [REL2NO3] nH2O (RE=La, Sm, Eu, Tb, Y, n=2; RE=Pr, Nd, n = 1; RE=Dy, Er, Yb, n=3), is given. These were characterized by IR, UV-Visible, 1H NMR, 13C NMR and fluorescence. The results show that the schiff base is a tridentate ligand, and the rare earth ions exhibit a coordination of eight in the complexes. In visible spectra, the supersensitive transitions of the Er complex at 522 nm (4 I15/2 -->2 H11/2, 4 S3/2 ) and that of the Nd complex at 573, 584 nm (4I9/2 -->2 G7/2 + 4G5/2) can be observed. Fluorescence of the complexes was produced principally by f-f transition of central ion RE3+, and the ligand has little influence on lightening role. The order of relative intensity of fluorescence of the complexes is ITb > ISm > IEu > IDy.