Structural characterization and cytotoxic activity of tioconazole coordination compounds with cobalt(II), copper(II), zinc(II) and cadmium(II)

Coordination compounds of CoII, CuII, ZnII and CdII with tioconazole (tcnz) have been synthesized and fully characterized by different techniques such as IR, UV–Vis–NIR, elemental analysis, molar conductivity, magnetic susceptibility and X-ray diffraction for the halide complexes. Different coordination geometries were stabilized by the metal ions in the obtained compounds. In all complexes the ligand is coordinated to the metal ions by the imidazolic nitrogen atom. The chloro and bromo [M(tcnz)2X2] compounds of CoII, ZnII, CuII and CdII presented a tetrahedral geometry with two ligands and two halides in the coordination sphere. In the CuII compounds with four ligands, [Cu(tcnz)4X2], a trans-octahedral geometry was acquired with the halides in axial positions. For the CuII and ZnII nitrato compounds [M(tcnz)2(NO3)2], a bidentate coordination mode of the nitrato groups stabilized a distorted cis-octahedral geometry, while in the pentacoordinated. [Cd(tcnz)3(NO3)2] compound a monodentate coordination was proposed. Additionally a binuclear [Cu2(tcnz)4(OAc)2) complex was obtained. In vitro cell growth inhibition on HCT-15 (colon), HeLa (cervix-uterine) and MCF-7 (breast) of the coordination compounds, as well for the free ligand, was investigated. Upon coordination, the IC50 value of the transition-metal compounds was improved compared to that of the free ligand. The copper(II) choro compounds showed the best cytotoxic activities on the HCT-15 cell line, being the most promising candidates for further in vitro and in vivo studies.