Synthesis, molecular modeling and antioxidant activity of new phenolic bis-azobenzene derivatives

Abstract New phenolic bis-azobenzene derivatives have been synthesized through reaction of 4-((2,4-dihydroxyphenyl)azo)-2-hydroxybenzoic acid with various diazotized anilines. The chemical structures of the prepared compounds were characterized by elemental and spectral analyses (IR, NMR and UV–Visible). The DFT geometry optimization of the bis-azobenezenes was carried out at B3LYP/6–311++G (d,p) level to indicate that they have a planar structure. The geometrical parameters, bond length and bond angle were in good agreement with those obtained from x-ray crystal structure of analogue compounds. The TD-DFT is used to obtain λ max and compared with the experimental UV–Visible absorption spectra. The HOMO-LUMO energy gap and other chemical reactivity descriptors were calculated. The antioxidant activity of the investigated compounds was screened. The data indicated that the methoxy derivative 5c exhibited higher activity than their corresponding derivatives with IC 50  = 23.01 μg/mL which close to the reference (Ascorbic acid, IC 50  = 22.03 μg/mL).