A new bio‐active Schiff base ligand and its Ni(II), Cu(II), Ag(I), Zn(II), Cd(II), and La(III) binuclear complexes: synthesis, DFT analysis, antimicrobial, DNA interaction, COXII inhibition, and molecular docking studies

Abstract

In the present work, 2‐hydroxy‐1‐naphthaldhyde and 2‐hydrazino‐N‐phenyl‐2‐thioxo‐acetamide are combined to create a new Schiff base. The novel ligand and its six new binuclear complexes with Ni(II), Cu(II), Ag(I), Zn(II), Cd(II), and La(III) are characterized via spectroscopic and analytical techniques, such as ultraviolet‐visible (UV–vis), infrared (IR), 1H NMR, 13C NMR, mass spectra, powder X‐ray diffraction (XRD), and thermogravimetric (TG) analysis. The spectral analysis indicated that the novel Schiff base may coordinate with the two metal ions. Additionally, the results indicated a square planar geometry for NiL, CuL, and AgL complexes and an octahedral geometry for ZnL, CdL, and LaL complexes. In contrast to the Schiff base ligand, different complex crystallinities were displayed in the powder XRD patterns. Significant thermodynamic parameter values were computed using the Coats–Redfern method which revealed high thermal stabilities of the complexes in the TG analysis. In vitro antibacterial, DNA‐binding, and anti‐inflammatory techniques were used for the biological evaluation. Moreover, to visualize the anti‐inflammatory action of complexes employing the cyclooxygenase enzyme receptor (PDB ID: 6COX), in silico docking was used. The serial dilution method evaluated the new compounds' in vitro antibacterial efficacy against three bacterial and one fungal strain. The results showed that the novel complexes showed remarkable efficiency against the bacterial growth of gram (+ve) Staphylococcus aureus compared to the parent ligand and the control. On the other hand, the ZnL, CdL, and AgL complexes showed excellent bactericidal activity. The inhibition of protein denaturation followed the following sequence: Ibuprofen > ZnL ˃ NiL ˃ AgL ˃ CuL > CdL > LaL > H2L. UV–visible and gel electrophoresis methods were used to examine the metal complexes and their ligand's affinity for binding DNA. An intercalative binding mechanism was suggested by the findings.