Synthesis, structure, DNA/protein binding, molecular docking and in vitro anticancer activity of two Schiff base coordinated copper(II) complexes

Two Schiff bases HL and HL′, having potential tridentate O,N,N′ donor sets, have been used for the synthesis of two copper(II) complexes, namely [Cu(HL)(pdc)]2 (1) and [Cu(L′)2]2 (2′), where HL = 2-([2-(piperazin-yl)ethylimino]methyl)phenol, pdc = py-2,5-dicarboxylate and HL′ = 2-(((2-(di-isopropylamino)ethyl)imino)methyl)phenol. X-ray single crystal analysis of complex 1 shows a centro-symmetric dimer. It crystallizes with a number of lattice water molecules that form a network of H-bonds, also involving the protonated piperazinium fragment, giving rise to a 3D supramolecular architecture. Complex 2′ also crystallizes as dinuclear, formed through mutual bridging phenol oxygen atoms as [Cu(L′)2]2, whilst an ESI mass spectrometry study evidences that in solution the complex exists as mononuclear [Cu(L′)2] (2). The interaction of complexes 1 and 2 with calf thymus DNA (CT-DNA) and with bovine serum albumin (BSA) was investigated using electronic absorption and fluorescence spectroscopic techniques. In both studies the results show a higher binding affinity of complex 1 in comparison to 2. The anticancer activity of the complexes against human breast (MCF7) cancer cell lines reveals that complex 1 has moderate growth suppression activity against these cells with an IC50 value of 24 ± 6.24 μM.