Synthesis, characterization, antioxidant evaluation, molecular docking and density functional theory studies of phenyl and naphthyl based esters

Two phenol based esters phenyl benzoate (OE₁) and 1-naphthyl benzoate (OE₂) were synthesized from phenol/1-naphthol and benzoyl chloride respectively. The structural elucidation of the synthesized compounds was accomplished by spectroscopic studies (FTIR, ¹H NMR & GC-MS) and single crystal X-ray diffraction analysis. DPPH (2, 2-diphenyl-1-picryl-hydrazyl-hydrate) free radical and hydrogen peroxide activities were performed to evaluate the antioxidant capabilities of the synthesized esters. The compounds (OE₁ & OE₂) showed DPPH scavenging activity in concentration dependent manner with IC₅₀ values 605.6 μM and 1138.7 μM correspondingly. Similarly, in hydrogen peroxide assay, OE₁ and OE₂ exhibited moderate activity with IC₅₀ values 1510.2 μM and 1069.4 μM respectively. Molecular docking of the compounds was carried out to predict their antioxidant binding mechanism against target protein using the MOE suite. The structure−activity relationship analysis showed that replacing the phenyl ring by naphthyl significantly influences their activity. Geometrical studies of the compounds have been performed by both semi-empirical and DFT methods; results reveal an excellent convergence of experimental and theoretical structural parameters. A detailed bonding investigation of each compound has been performed by NBO and Bader's AIM analysis to obtain inter and intramolecular interactions.