Syntheses, Structures and Cytotoxicity of Cu(II) Complexes with α-Amino acid derived Benzamidines

N-(diethylthiocarbamoyl)benzimidoyl chloride reacts with methyl esters of glycine, L-alanine, L-valine under formation of proligands 1 which undergo de-esterification in reactions with Cu(CH3COO)(2) and finally form complexes 2 with the compositions of [{Cu(L-gly)}(4)] (2 a), [{Cu(L-ala)}(infinity)] (2b) and [{Cu(L-val)}(infinity)] (2c). In all complexes, Cu(II) ion is coordinated by a dianion {L-2(-)} via its (O,N,S) donor set and a bridging carboxylate 0 atom, and thus, adopts a distorted square-planar coordination sphere. Treatment of complexes 2 with equimolar amounts of o-phenanthroline results in the formation of square pyramidal ternary complexes with the compositions of [Cu(L)phen] (L=L-gly, L-ala, L-val) (3). Antiproliferative effects of the compounds on MCF-7 and Hep-G2 cancer cells were studied. Generally, the ternary complexes 3 are more active than the complexes 2 and the pro-ligands 1. In each series of compounds, the derivatives of L-valine show higher cytotoxicity than those of L-alanine and glycine.