Biological evaluation, molecular docking, DNA interaction and thermal studies of new bioactive metal complexes of 2‐hydroxybenzaldehyde and fluorobenzamine Schiff base ligand

Abstract

Schiff base ligand named 2‐((E)‐(2‐fluorophenylimino)methyl)phenol (HL) was prepared by the condensation of 2‐hydroxybenzaldehyde and 2‐fluorobenzamine in 1:1 molar ratio. The coordination behaviour of a series of transition metal ions with the synthesized HL ligand, [Cr(HL)2] (1), [Fe(HL)2] (2), [Co(HL)2] (3) and [Cu(HL)2] (4) is reported. The structure and bonding of the metal complexes have been deduced by analytical and spectral studies. Based on the above studies, the metal centres were found to be octahedral for all the complexes. The activation thermodynamic properties were calculated using the Coats–Redfern method. Thermal decomposition processes of complexes 1, 2, 3 and 4 are non‐spontaneous; that is, the complexes are thermally stable. The positive value of Gibbs free energy of decomposition (ΔG*) for all the complexes is non‐spontaneous processes. DNA binding properties of these metal complexes, investigated using UV–visible absorption, fluorescence and viscosity measurement studies, imply that the complexes bind to DNA by intercalation. The intrinsic binding constant Kb from the electronic absorption studies are 3.12 × 104 M−1, 1.86 × 104 M−1, 3.96 × 104 M−1 and 5.89 × 104 M−1, and the Stern–Volmer quenching constant Ksv values from fluorescence studies are 2.29 × 104 M−1, 1.92 × 104 M−1, 5.62 × 104 M−1 and 8.91 × 104 M−1, for the complexes 1, 2, 3 and 4, respectively. DNA photo cleavage activities of these complexes were studied with supercoiled pUC19 DNA, in the presence of H2O2. GOLD 3.1 program was used to evaluate binding affinities of complexes with human DNA topoisomerase I protein. in vitro cytotoxic and antimicrobial studies revealed higher activity of metal complexes, compared with the ligand.