Synthesis, spectral characterization, biological and fluorescence studies of lanthanum(III) complexes with 3-substituted-4-amino-5-hydrazino-1,2,4-triazole Schiff bases

Some lanthanum(III) complexes have been synthesized by reacting lanthanum(III) nitrate with Schiff bases derived from 3-substituted-4-amino-5-hydrazino-1,2,4-triazole and substituted salicylaldehydes. All these complexes are soluble in DMF and DMSO and the low molar conductance values observed indicates that they are non-electrolytes. Elemental analyses suggest the complexes have 1:1 stoichiometry of the type La · L · NO₃ · H₂O, and they were characterized further by spectral and thermogravimetric methods. Fluorescence spectra of one of the representative Schiff bases (II) and its lanthanum(III) complex were investigated in various solvents; the complexes were evaluated for their biological activity.