Copper(II) pseudohalide complexes with isomeric N2O donor Schiff base ligands: Synthesis, characterization and molecular dynamics simulations of interactions with DNA

Two new square planar copper(II) complexes, [Cu(L-1)(NCO)] (1) and [Cu(L-2)(N-3)] (2), where HL1 = 1-(- 1-(2-(diethylamino) ethylimino) ethyl) naphthalen- 2- ol and HL2 = 2-(-(2-(diethylamino) ethylimino) methyl) naphthalen-1-ol, have been synthesized and characterized by elemental analysis, IR, UV-VIS and single-crystal X-ray diffraction studies. Interaction of the complexes with calf thymus DNA (c t DNA) was studied by UV-VIS spectroscopy that revealed complex 2 had a slightly greater affinity for DNA. The mode of binding for both complexes was by the process of intercalation as confirmed by monitoring the fluorescence during a reverse titration on calf thymus DNA earlier saturated with ethidium bromide (a well-established DNA intercalator). The overall binding constant (K*) were 5.36 x 10(4) and 17.91 x 10(4) for complexes 1 and 2 respectively. The binding mode for complex 1, using a generic dodecamer fragment of the DNA used was modeled using molecular dynamics (MD), with results that were consistent with experimental observations.