A comparative analyses of bioactive Cu(II) complexes using Hirshfeld surface and density functional theory (DFT) methods: DNA binding studies, cleavage and antibiofilm activities

Two mononuclear Copper(II) complexes, [Cu(dip)₂] (1) and [Cu(dimp)₂] (2) have been synthesized and characterized thoroughly by various spectroscopic techniques and single crystal X-ray diffraction analysis. Dispersion corrected B3LYP/DFT calculations have been carried out to elucidate the tentative assignments of N-Cu-N/O-Cu-O/O-Cu-N and other significant vibrational modes. Additionally, quantitative analysis of intra and intermolecular non-covalent interactions were carried out using Hirshfeld surface calculations to explore H-bonding, C–H/π and Cu…H–C interactions. In vitro DNA binding studies of 1 and 2 were performed by employing optical spectroscopic techniques. The cleavage activity of 1 and 2 with pBR322 plasmid DNA was carried out by gel electrophoretic assay and it was observed that both 1 and 2 cleaved DNA by oxidative pathway via ROS species viz., O₂⁻,¹O₂etc. Furthermore, antibiofilm activity of the complexes 1 and 2 was evaluated against E. Coli 25922 and it was found to interfere and inhibit the biofilm forming ability of E. Coli 25922.