Water soluble Cu(II) and Zn(II) complexes of bidentate-morpholine based ligand: synthesis, spectral, DFT calculation, biological activities and molecular docking studies

Abstract

Copper(II) and zinc(II) complexes of the type [ML(AcO)2.H2O] were synthesized from bidentate-morpholine based Schiff base ligand (L - morpholinopropylimino)methyl)-6-methoxyphenol). The prepared ligand, copper(II) and zinc(II) complexes were characterized by elemental analysis, ESI-MS, 1H-NMR, FT-IR, UV-Visible, ESR and spectrometric methods. The elemental and ESI-MS results have been established that the prepared ligand and complexes possess 1:1 stoichiometric ratio. 1H-NMR and FT-IR results have been suggested that azomethine nitrogen and morpholine ring nitrogen atoms are coordinated with Cu(II) and Zn(II) metal ions. UV-Visible, ESI-MS and ESR spectroscopic results have been supported that the proposed structure of Cu(II) and Zn(II) complexes possess square pyramidal geometry. In order to confirm the proposed square pyramidal geometry of prepared complexes by DFT calculation has been studied. DNA binding ability of Cu(II) and Zn(II) complexes have been studied by electronic absorption and viscometric methods. These results reveal that Cu(II) and Zn(II) complexes interact with CT-DNA by the way of groove binding mode. Molecular docking studies result shows that synthesized compounds has better binding ability. The in vitro antioxidant activities of ligand, Cu(II) and Zn(II) complexes have been investigated by using the DPPH assay. The result shows that synthesized compounds have good radical scavenging activity against DPPH radical. Antimicrobial activities of synthesized ligand and its complexes have been tested against selected bacterial (gram positive & gram negative) and fungal species. The results reveal that Cu(II) and Zn(II) have good antimicrobial activity than ligand. Communicated by Ramaswamy H. Sarma