DNA/protein interaction, cytotoxic activity and magnetic properties of amino-alcohol Schiff base derived Cu(II)/Ni(II) metal complexes: influence of the nuclearity and metal ions

Four coordination complexes based on two amino-alcohol derived Schiff base ligands, namely, [Cu(H2L1)(Cl)].CH3OH (1), [Cu-4(HL2)(2)(H2L2)(2)(H2O)(C2H5OH)].2(ClO4).2(C2H5OH) (2), [Ni-2(H2L1)(2)(OAc)(2)(C2H5OH)(2)](2) (3) and [Ni-4(HL2)(3)(mu(3)-O)(H2O)(3)].9H(2)O (4) (H3L1 = {2-ethyl-2-((2-hydroxybenzylideneamino)propane-1,3-diol), and H3L2 = 2-ethyl-2-((2-hydroxy-3-methoxybenzylideneamino)propane-1,3-diol)}), were synthesized and characterized. Alkoxo and phenoxo groups of the Schiff base ligands bridge the metal atoms in diverse modes, leading to interesting mononuclear (1), dinuclear (3), and tetranuclear (2 and 4) complexes, respectively. The in vitro cytotoxic effect of these complexes on cancerous cell lines, including the human lung carcinoma cell line (A549), human colon carcinoma cell lines (HCT-116), human promyelocytic leukemia cells (HL-60) and the chronic myelogenous leukemia cell line (K-562) showed that all these complexes exhibited substantial cytotoxic activity. Their interactions with calf thymus DNA (CT-DNA) and bovine serum albumin (BSA) were also investigated using UV-visible, fluorescence and synchronous fluorescence spectroscopic methods. All complexes could quench the intrinsic fluorescence of BSA in a static quenching process. Variable temperature magnetic properties of these complexes were investigated in details. The nuclearity and metal centers play an important role in the properties of the complexes.