Synthesis, structure, and cytotoxicity of complexes of zinc(II), palladium(II), and copper(I) chlorides with (-)-camphor thiosemicarbazone

Complexes [Zn(L-2)(2)Cl-2], [Pd-2(L-2)(2)Cl-4], and (CuLCI)-C-2, where L-2 is (-)-camphor thiosemicarbazone, were synthesized. The structures of complexes [Zn(L-2)(2)Cl-2] and [Pd-2(L-2)(2)Cl-4] were determined by X-ray diffraction. The crystal structure of complex [Zn(L-2)(2)Cl-2] contains mononuclear molecules with distorted tetrahedral (ZnCl2S2) coordination units and monodentate L-2 ligands. Complex [Pd-2(L-2)(2)Cl-4] has binuclear structure with Pd metal centers linked by L-2 ligands via mu(2)-S atoms. Complex (CuLCI)-C-2, according to IR and NMR spectra contains S and Cl atoms in the coordination sphere of ion Cu+. Complexes [Pd(tsc)Cl-2] and Zn(tsc)(2)Cl-2 (where tsc is thiosemicarbazide) were also obtained to determine the influence of the terpene moiety on cytotoxic properties of these compounds. Mononuclear complex [Pd(tsc)Cl-2] contains an NSCl2 planar square coordination polyhedron, and tsc is a bidentate chelate ligand. The effects of tsc, L-2, and the complexes with tsc and L-2 on viability of the MCF-7 cell line were investigated next. The results showed that tsc and L-2 are nontoxic at the tested concentrations (1-50 mu M). All the complexes exerted a significant dose-dependent cytotoxic effect, whereas complex (CuLCI)-C-2 was found to have the lowest half-maximal inhibitory concentration (IC50). (C) 2019 Elsevier Ltd. All rights reserved.