Synthesis, spectroscopic and antibacterial studies of zinc(ii) and copper(ii) complexes containing amino acid thiourea ligands

The study on thiourea derivatives and its coordination complexes have been well documented with majority of the synthesized compounds have high potential to be used as antibacterial agents. In line with this interest, two thiourea ligands derived from amino acids, namely 2-(3-dodecanoyl-thioureido)-3-methylbutyric acid (L1) and 2-(3-dodecanoylthioureido)-3-phenylpropionic acid (L2) have been reacted with ZnCl2 and CuCl2, to produce three new complexes with general formula of [Zn(L1)Cl2] (1), [Zn(L2)Cl2] (2) and [Cu(L2)Cl2] (3) as suggested by elemental analysis. The complexes were characterized by spectroscopic techniques such as Fourier Transform Infrared (FTIR) and Ultraviolet-Visible (UV-Vis). The antibacterial activities of the complexes were evaluated against three common Gram-positive strains (S. aureus, S. epidermidis and B. subtilis) and two Gram-negative strains (E. coli and S. typhimurium). This study revealed that complex 3 had a good antibacterial activity towards Gram-positive strain namely S. epidermidis while complexes 1 and 2 showed moderate activities against all bacteria