Synthesis, Characterization, DNA Binding, DNA Cleavage and Antimicrobial Studies of Schiff Base Ligand and its Metal Complexes

Abstract

A series of Cu(II), Ni(II), Co(II), Mn(II) and Zn(II) complexes have been synthesized from the Schiff base ligand L. The Schiff base ligand 4-chloro-2-((4-oxo-4H-chromen-3yl) methylene amino) benzoic acid (L) has been synthesized by the reaction between chromone-3-carbaldehyde and 4-chloro-2-amino benzoic acid. The nature of bonding and geometry of the transition metal complexes as well as ligand L have been deduced from elemental analysis, FT-IR, UV-vis, (1)H NMR, (13)C NMR, ESR spectral studies, mass, magnetic susceptibility and molar conductance measurements. The complexes are found to have ML2 composition and are neutral in DMSO. Based on elemental, conductance and spectral studies, six-coordinated geometry was assigned for these complexes. The ligand L acts as tridentate and coordinates through nitrogen atom of azomethine group, hydroxyl of the carboxyl group and oxygen atom of keto group of γ-pyrone ring. The interaction of Cu(II) complex with CT-DNA was carried out by UV-vis, fluorescence titrations and viscosity measurements. The complex binds to DNA through intercalative binding mode. The nuclease activity of the above metal complexes shows that Cu(II) and Co(II) complexes cleave DNA through redox chemistry. The biological activity of the ligand and its complexes have been studied on four bacteria E. coli, B. subtilis, pseudomonas and Edwardella and two fungi penicillium and trichoderma by well disc and fusion method and found that the metal complexes are more active than the free Schiff base ligand.

Antimicrobial and antibiofilm activities of Cu(II) Schiff base complexes against methicillin-susceptible and resistant Staphylococcus aureus

“…In this study, SBD2 and SBD4 showed enhanced inhibitory activities against the planktonic SA and MRSA, possibly due to complexation, improved permeability and increased molecular weight [ 13 ]. Other than S. aureus , studies have also shown that Schiff base copper complexes have enhanced antimicrobial ability against Enterococcus faecalis , E. coli , Salmonella typhi , Klebsiella pneumoniae , P. aeruginosa and B. subtilis [ 7 , 14 – 16 ].…”

Synthesis, Spectral Characterization, DNA Binding, Cleavage and Biological Evaluation on Co(II), Ni(II) and Cu(II) Complexes of Substituted Isoxazole Schiff Bases

“…12) show a which was shown by the antibacterial and . The enhancement of C=N-group and metal ion in complexes [41]. This enhanced antimicrobial activity nature of metal complexes was demonstrated by Overtone [42] and the chelation Tweedy [43].…”

“…12) show a zone of inhibition area which was shown by the test compounds against the antibacterial and antifungal strains. The enhancement of antimicrobial activity is due to -C=N chelation effect with a metal ion in complexes [41]. This enhanced antimicrobial activity nature biological screening activities of Schiff base ligands and their complexes were investigated against bacterial and fungal strains.…”

Bio-relevant complexes of novel N2O2 type heterocyclic ligand: Synthesis, structural elucidation, biological evaluation and docking studies

“…8, it is found that the activity of imine ligand is enhanced when coordinated to the metal ions. The presence of imine group (-C=N) and chelation effect with central metal enhances the anti-pathogenic actions [40]. Moreover, it has been already proved that the ligand contains nitrogen and oxygen donor systems might restrain enzyme production, since the enzymes which require these group for their activity appear to be especially more susceptible to deactivation by the metal ion upon chelation.…”