Effect of the replacement of tripodal 4N donors by two 2N chelators on the redox and cytotoxic activity of maltolato and deferipronato containing Co(III) complexes

Fourteen novel Co-III ternary complexes with the general formula [Co(4N)(2O)]X-2 or [Co(2N)(2)(2O)]X-2 where 4N = tris(2-aminoethyl)amine (tren) or tris(2-pyridylmethyl)amine (tpa); 2N = 1,10-phenantroline (phen), 2,2'-bipyridine (bipy), 1,2-diaminoethane (en) or 2-(aminomethyl)pyridine (ampy) and 2O = 1,2-dimethyl-3-hydroxy-4(1H)-pyridinone (dhpH), 3-hydroxy-2-methyl-4-pyrone (maltH) or 2-ethyl-3-hydroxy-4H-pyran-4-one (etmaltH) were synthesized, characterized and their redox features explored. Molecular structure of some selected [Co(2N)(2)(2O)](ClO4)(2) (2N = phen, bipy, en; 2O = dhp, malt) or [Co(4N)(2O)](ClO4)(2) (4N = tpa; 2O = etmalt) type complexes were assessed by X-ray diffraction and showed the expected octahedral geometry. Replacement of the 4N donor ligands by two 2N donor ligands resulted in the decrease of the cathodic peak potential of the complexes indicating easier reduction and allowing therefore the tailoring of the redox properties of the complexes. Screening of selected compounds against a human derived cancer cell line, HeLa, showed that, unlike the [Co(4N)(2O)]X-2 derivatives, the complexes containing 2N = bipy or phen ligands have better anticancer activity than cisplatin or carboplatin.

Automated summary

Fourteen novel Co-III ternary complexes with different ligands were synthesized and characterized, revealing their molecular structures and redox properties. X-ray diffraction analysis showed the expected octahedral geometry, and the replacement of 4N donor ligands with 2N donor ligands resulted in easier reduction of the complexes, indicating tailoring of their redox properties. Screening against a human derived cancer cell line demonstrated that complexes containing bipy or phen ligands have better anticancer activity than cisplatin or carboplatin.