Synthesis and characterization of mixed-ligand Zn(II) and Cu(II) complexes including polyamines and dicyano-dithiolate(2-): In vitro cytotoxic activity of Cu(II) compounds

Potentially bi-, tri- and tetra-dentate polyamines (1,3-diaminopropane (pn); diethylenetriamine (tren), tris(2-aminoethyl)amine (tetraen)) react with divalent zinc and copper nitrate salts in the presence of 1,1-dicyano-2,2-ethylenedithiolate dipotassium salt (K2i-mnt) to afford a variety of mixed ligand complexes. X-ray diffraction analysis evidences that dithiolate acts as a counter di-anion in the octahedral zinc derivative [Zn(tren)2(i-mnt)] (1), or participates directly in metal coordination in the trigonal–bipyramidal complex [Zn(tetraen)(i-mnt)] (2). Various interactions in the crystal packing of 1 and 2 are substantiated by Hirshfeld Surface analysis study. The antiproliferative activity of metal complexes has been studied toward a panel of human tumor cell lines of different histology, with different cisplatin-sensitivity, grown as 2D cultures. In addition, as cell spheroids generated from 3D cell cultures are more similar to real tumors in terms of tissue morphology, biology and gene expression, a 3D cell culture efficacy study with copper complexes across colon and non-small lung cancer cells has been performed.