Structural characterization and cytotoxic evaluation of Cu(II), Co(II) and Ni(II) complexes with herbicide 4-chloro-2-methylphenoxyacetic acid

The purpose of our research was to obtain and characterize Cu(II), Co(II) and Ni(II) complexes with herbicide 4-chloro-2-methylphenoxyacetic acid (MCPA). The structural characterization of compounds in their powder form was based on various laboratory as well as synchrotron X-ray spectroscopic methods, magnetic measurements and atomistic calculations. The anhydrous [Cu(MCPA)2]n complex exhibits a distorted square-planar geometry. [Co(MCPA)2(H2O)4]·H2O and [Ni(MCPA)2(H2O)4]·H2O complexes have octahedral molecular geometry with two MCPA anions acting as monodentate ligands. The X-ray crystal structure analysis performed for Cu(II) complex after its recrystallization from N,N-dimethylformamide solution showed the formation of dinuclear complex with solvent molecules included in the coordination sphere of Cu(II). MCPA herbicide and its Cu(II), Co(II) and Ni(II) complexes showed the low cytotoxicity potential against HaCaT and V79 cells with IC50 in the range from 65 to >100 µM.