Synthesis, spectral characterization and DNA bindings of tridentate N2O donor Schiff base metal(II) complexes

• Synthesis of metal(II) complexes with N, N and O donor Schiff base ligand.
• Ligand and its metal(II) complexes have been completely characterized.
• These metal(II) complexes may bound on the grooves of HS-DNA.
• All the complexes shows significant cleavage of pBR322 DNA.
• AFM study displayed a ruptured cell wall morphology of E. Coli by Co(II) complex.

To evaluate the biological preference of synthetic small drugs towards DNA target, new metal based chemotherapeutic agents of Cu(II), Co(II), Ni(II) and Zn(II), 2,4-diiodo-6-((pyridin-2-ylmethylimino)methyl)phenol (L) Schiff base complexes (1, 2, 3 & 4) having N,N,O donor system respectively were synthesized and thoroughly characterized. The IR results confirmed the tridentate binding of the ligand with metal centre during complexation and reflects the proposed structure. The density function theory calculations were also used to further investigate the electronic structure and properties of ligand and complexes. The preliminary investigation of herring Sperm (HS-DNA) interaction propensity of complexes 1–4 were carried out in Tris–HCl buffer at pH 7.1 to demonstrate their mode of interactions. The obtained results reveal that these complexes significantly interact with DNA on the grooves, further, this observed mode of interactions was also confirmed by molecular docking evaluations. The complexes 1–4 were also screened for antimicrobial evaluations which demonstrated that their significant activity against various human pathogens. The cleavage studies with pBR322 plasmid DNA revealed higher nuclease activity of 1 as compared to other complexes.

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