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.
