Phenanthroline and hydroxyurea-based Co(iii) complexes: synthesis, characterization and investigation of biological potential†

Abstract

It is undeniable that society has made significant advances in developing products and technologies to treat and remedy various diseases affecting the population. However, some neglected diseases still have few treatment options. Therefore, conducting studies to develop treatment options for this group is relevant. To leverage the versatile properties of coordination compounds, this study focuses on the development of cobalt(III)-based coordination compounds using hydroxyurea (HU) and o-phenanthroline (phen) as ligands. The complexes cis-[CoCl₂(phen)₂]Cl·3H₂O and cis-[Co(HU)₂(phen)₂]Cl₃·2H₂O were synthesized and characterized using various analytical techniques. The ¹³C NMR spectrum confirmed that hydroxyurea is part of the composition of cis-[Co(HU)₂(phen)₂]Cl₃·2H₂O. Based on the vibrational spectrum (FTIR), HU coordinates to Co(III) through the oxygen atom (carbonyl). Elemental and thermal analyses supported the proposed compositions, and the X-ray powder diffraction data indicated a strong similarity in the crystal structures between both compounds. Additionally, UV-vis and chromatographic data indicated reactivity in water for cis-[Co(HU)₂(phen)₂]Cl₃·2H₂O, with the release of the HU ligand. Once well-characterized, the compounds were evaluated against T. cruzi protozoa, as well as bacterial and fungal strains. As a result, cis-[CoCl₂(phen)₂]Cl·3H₂O exhibited trypanocidal activity, similar to benznidazole, against the trypomastigote and amastigote forms of T. cruzi, in non-toxic concentrations for cardiomyocytes. The antiparasitic activity of cis-[CoCl₂(phen)₂]Cl·3H₂O is linked to the formation of membrane blebs, body deformation, and the loss of plasma membrane integrity in the parasites. Furthermore, cis-[Co(HU)₂(phen)₂]Cl₃·2H₂O demonstrated antimicrobial activity against two bacterial strains (Staphylococcus aureus and Bacillus subtilis). Given that the compounds exhibit expected characteristics and demonstrate multiple types of biological activity, it is important to continue studying them to elucidate their mechanisms of action and identify other potential activities.