Fabrication, structural, DFT, biological and molecular docking studies of Fe(III), Ni(II), and Cu(II) complexes based on Schiff-base derived from benzene-1,4-diamine and 2-hydroxy-1-naphthaldehyde

Abstract

This study presents the design & comprehensive characterization of three novel metal complexes derived from a Schiff base compound (H₂PDN) synthesized from benzene-1,4-diamine and 2-hydroxy-1-naphthaldehyde, coordinated with Fe (III) (FePDN), Ni (II) (NiPDN), & Cu (II) (CuPDN). Structures of both the H₂PDN ligand & its metal complexes were proposed utilizing various analytical methods, having elemental analysis, ultraviolet–visible spectroscopy, mass spectrospcopy, infrared spectroscopy, magnetic properties, conductivity measurement, & thermal analysis. The obtained data revealed octahedral geometries for both FePDN and CuPDN complexes, denoted as [Fe₂(PDN)(H₂O)₄(Cl)₄] and [Cu₂(PDN)(H₂O)₆(Cl)₂], respectively, while the NiPDN complex exhibited a distorted tetrahedral structure, represented as [Ni₂(PDN)(H₂O)₂(Cl)₂]. Density functional theory (DFT) computations were employed to validate the molecular structures & explore quantum chemical parameters of both H₂PDN & its metal complexes. The synthesized H₂PDN Schiff base and its metal complexes (FePDN, NiPDN, CuPDN) showcased significant antimicrobial, anti-inflammatory, and antioxidant activities. NiPDN exhibited the highest inhibition zone against P. aeruginosa (21.44 ± 0.28 mm) and S. aureus (19.37 ± 0.40 mm), while CuPDN showed strong inhibition against E. coli (18.42 ± 0.13 mm). NiPDN demonstrated excellent antibacterial efficacy with a low MIC against B. cereus (21.00 ± 0.98 μM), and CuPDN displayed potent anti-inflammatory (IC50: 121.65 μM) and antioxidant activity (IC50: 84.7 ± 0.77 μM). These results indicate the therapeutic potential of the H₂PDN complexes. Molecular docking studies targeting specific proteins (2VF5 for Escherichia coli, 3CKU for Aspergillus flavus, 5IKT for Human Cyclooxygenase-2, & 5IJT for human peroxiredoxin 2) were performed to assess the binding affinities & interactions of H₂PDN & its metal complexes. The results propose promising potential for the application of H₂PDN and its metal complexes as novel therapeutic agents with diverse biological activities.