Synthesis, Characterization and Bioactivity of Two Rare-Earth Complexes with Schiff Base from Lysine-Salicylaldehyde

Abstract

Two novel rare earth complexes with Schiff base from Lysine-Salicylaldehyde were synthesized by using the drop by drop reaction. On the basis of molar conductance and elemental analysis, a formula of the target complex was given. Moreover, the target complexes were also characterized by IR and UVvisible. The antibacterial experiments indicated that the target complexes have good antibacterial activities against S. aureus, E. coli, B. subtillis and P. aeruginosa. Keywords—Lysine-Salicylaldehyde ;Schiff base; Rare-Earth Complexes; Synthesis; Bioactivity. Introduction Schiff bases and their metal complexes have been widely Used in medicines, industrial catalysis, chemical analysis, metal corrosion and photochromism , due to their special biological functions. Early in the middle of the twentieth century, Rasenberg have found that amino acid-Schiff bases could inhibit cell division of E. coli. And then, a new field in the drug discovery research has been inaugurated since the antibacterial and anticancer activities of amino acid-Schiff bases were confirmed in 1969 .In recent years, with the development of functional complexes and bioinorganic chemistry, transition metal complexes of amino acid-Schiff bases also have made considerable progress. For example, they can be used as anticarcinogen, catalyzer of transamination of vitamin B6, carrier of biotic ligand model, antioxidant, and so on. Therefore, to study the amino acidSchiff base complex is very significant. In this study, two novel of Rare-Earth (indium and thorium) Complexes with Schiff base from LysineSalicylaldehyde (Lys-Sal) were synthesized via the drop by drop reaction. The title complexes were confirmed by molar conductance, elemental analysis, IR and UV-visible. The bioassay revealed that the title complexes displayed good antibacterial activities. For example, they were effective in controlling S. aureus, E. coli, B. subtillis and P. aeruginosa. And to our knowledge, indium and thorium complexes with Lys-Sal Schiff base have not been reported.