Synthesis, structure, DNA binding, cleavage and biological activity of cobalt (III) complexes derived from triethylenetetramine and 1,10 phenanthroline ligands

•Two cobalt (III) complexes were synthesized.•These complexes bind and cleave DNA.•They are potential anti-microbial agent.•The complexes have the potential to kill human liver cancer cells.

The cobalt (III) complexes, [Co(trien)(phen)] (ClO4)2Cl, (1), [Co(trien)(phen)](NO3)3, (2) (where trien = triethylenetetramine, phen = 1,10-phenanthroline) has been synthesized and characterized by Infra-red, UV–Vis, ESI-MS and elemental analysis methods. Complex 1 was structurally characterized by single crystal X-ray crystallography. It was crystallized in a triclinic system with space group P1¯, a = 7.797(10) Å, b = 10.6584(2) Å, c = 14.889(3) Å, α = 96.83(10)°, β = 96.16(10)°, and γ = 98.88(10)°. The cobalt atom assumes a distorted octahedral geometry by coordinating to 6 nitrogen atoms from four triethylenetetramine and two 1,10-phenanthroline ligands. The binding of this cobalt (III) complex with calf thymus DNA (CT-DNA) was investigated by UV–Vis absorption, fluorescence spectroscopic, cyclic voltammetric and viscosity techniques. Also, the interactions of pBR322 DNA with these cobalt (III) complexes were studied using the gel electrophoresis method. The thermal denaturation and viscosity binding data advocates that the cobalt (III) complexes interact with DNA by groove binding. When compared to complex 2 complex 1 has more potential to the kill human liver cancer cell as revealed by the MTT assay. The cobalt (III) complexes screened for their activities in vitro on common bacteria and fungi and exhibit antimicrobial activities.

Graphical abstractTwo novel mononuclear cobalt (III) complexes, [Co(trien)(phen)] (ClO4)2Cl, (1), [Co(trien)(phen)](NO3)3, (2) were synthesized and characterized. Complex 1 was structurally characterized by single crystal X-ray crystallography. The binding property of the complexes with CT-DNA has been studied using different analytical methods. Both the complexes cleave DNA more efficiently. One of the complexes displayed higher anticancer activity (IC50 = 59.89 ± 0.2 μg/ml) against HepG2 cancer cell line.Figure optionsDownload full-size imageDownload as PowerPoint slide