Synthesis, crystal structure and relevant antiproliferative activity against Toxoplasma gondii of a new binuclear Co(II) complex

The crystal structure of [(HPClNOL)Co(-μ-Cl2)Co(HPClNOL)](ClO4)21 (HPClNOL: 1-(bis-pyridin-2-ylmethyl-amino)-3-chloropropan-2-ol) revealed a distorted octahedral geometry around both Co(II) centers. The coordination plane comprised one tertiary amine, one alcohol in the protonated form and two chloride which link the two Co(II) centers, resulting in the binuclear arrangement. Two pyridine nitrogen atoms are coordinated and occupy the axial sites. Investigations in solid state and in solution (dimethylformamide) carried out by electronic spectroscopy suggest that the arrangement in the solid state changes in solution. Furthermore, ESI(+)-MS and conductivimetry studies indicated the formation of mononuclear species in solution in agreement with the lability of the chloride ligands. Complex 1 reduced the growth of Toxoplasma gondii infecting LLC-MK2 host cells. After treatment this complex reduced T. gondii growth by 55%, the ligand HPClNOL had no effect on parasite growth and sulfadiazine (SDZ), traditional terapeutic compound for this parasite, was effective only after 48 h of treatment. These results suggest the relevance of the cobalt ion on the anti-toxoplasma activity.