New copper(II) cyclam complexes with aminocarboxylate co-ligands: Synthesis, characterization, and in vitro antiproliferative and antibacterial studies

Abstract

Two new cationic Cu(II) complexes of cyclam (1,4,8,11-tetraazacyclotetradecane) and aminocarboxylate coligands glycine or alanine have been synthesized. The complexes were characterized by elemental analysis (C, H and N), molar electrical conductivity, magnetic susceptibility measurement at room temperature, spectral methods (UV/Vis and Fourier transform infrared), as well as by thermogravimetric (TG) and differential thermal analysis (DTA). The analytical data of the complexes show the formation of mononuclear complexes with general formula [Cu(L)cyc](ClO4)2·nH2O, A) L = glycine, n = 1.5 and B) L = alanine, n = 2.5. The tetradentate ligand cyclam was coordinated to metals through four N donors. The spectroscopic data suggested that the amino carboxylate ligands coordinated via their carboxylate ion moieties. The six- -coordinate octahedral geometry around Cu(II) in both complexes was presumed. TG-DTA analysis indicated that complex B decomposed exothermally in a single step in the range of 310–400°C. The cytotoxic activity of Cu(II) complexes and the starting ligands were tested against human cervix adenocarcinoma cell line (HeLa), human melanoma (FemX) and human colon carcinoma (LS174). The IC50 values for the Cu(II) complexes were from 48.35–82.25 μM. Both complexes were tested for their antimicrobial activity against Staphylococcus aureus, Bacillus subtilis, Escherichia coli and the yeast Candida albicans.

Keywords

• copper(ii) complexes
• cyclam
• glycine
• alanine
• antimicrobial and cytotoxic activity