Synthesis, mechanism and NMR spectra of lanthanide complexes with a novel unsymmetrical Schiff base

Owing to its two unsymmetrical-NH2 groups sited on different terminals, 2, 6-diaminocaproic acid (lysine) was used as a reactant for synthesizing a no vel unsymmetrical Schiff base with salicylaldehyde on one side and o-vanili in on the other for the first time. It is a new way to synthesize such a sp ecial unsymmetrical Schiff base. It is named "hetero bis-Schiff base" for d istinguishing it from others. The synthesis method, formation mechanism as well as twelve new lanthanide complexes with the above ligand are reported and discussed herein. They were characterized by elementary analysis, molar conductivity, IR-spectra and especially by H-1 and C-13 NMR spectra. The r esults obtained may provide a new promising method for synthesizing similar unsymmetrical Schiff bases and their complexes.