Designing, characterization, biological, DFT, and molecular docking analysis for new FeAZD, NiAZD, and CuAZD complexes incorporating 1-(2-hydroxyphenylazo)- 2-naphthol (H2AZD)

Herien, three new Fe(III) (FeAZD), Ni(II) (NiAZD), and Cu(II) (CuAZD) complexes were synthesized and characterized using various physicochemical and spectroscopic approaches. The H₂AZD ligand acted as a bi-basic bi-dentate NO ligand in a 1:1 molar ratio. The results revealed that the FeAZD and CuAZD complexes had octahedral geometry, while the NiAZD had a tetrahedral geometry. The optimized geometry, HOMO and LUMO analysis of the ligand and its metal complexes was determined via Density functional theory (DFT) using the B3LYP with 6-311 G(d,p), and LanL2DZ level of theory. The FeAZD, NiAZD and CuAZD had lower energy gap, 7.40, 7.93 and 7.06 eV, respectively, than the free ligand (9.58 eV), which proposed that CuAZD was more active one. The free ligand and its metal complexes were in vitro investigated for their antibacterial and antifungal activity. The results illustrated that the metal complexes had higher antibacterial and antifungal activity than the free ligand. More specifically, the CuAZD demonstrated good antibacterial activity against E. coli, P. aeruginosa, S. aureus, B. cereus, and A. flavus, T. rubrum, and C. albicans, with activity indexes of 72.22%, 65.01%, 77.78%, and 72.22%, 63.16%, 59.09%, and 61.90%, respectively. Also, the metal complexes showed lower MIC (6.25-3.125 ppm) compared to the free ligand (about 50 ppm). Finally, molecular docking was utilized to investigate the ability of the free ligand and its metal complexes to inhibit the growth of E. coli (PDB ID: 5iq9). The results showed that the CuAZD had the highest binding affinity to the receptor, with a more negative docking score of - 7.05 Kcal/mol, and lower inhibition constant (Ki) of 6.90 µM. That is indicating that it may be the most effective at inhibiting the growth of E. coli (PDB ID: 5iq9).