Synthesis, Antibacterial Evaluation, and Prediction of the Ability of Corrosion Inhibition by Density Functional Theory of Azo-dyes of Folic Acid

In this study, new folic acid (B9) derivatives (a–d) were synthesized by reacting diazonium salt (of folic acid) with different aromatic compounds including 1-naphthol, 2-naphthol, pyrocatechol, or resorcinol. One of Schiff bases (I) was prepared by reacting folic acid with 4-amino benzaldehyde. Then, azo compound (e) was synthesized by coupling Schiff base with 1-naphthol. The new azo compounds (a–e) were identified by FTIR, 1HNMR spectroscopy, and by measurements of some physical properties. The current work investigated the physical characteristics of compounds (a–e) in order to select the best corrosion inhibitor. 6-311G+/(d, p) base set and Density Functional Theory (DFT) were employed to evaluate inhibition effectiveness. Physical features including ionization energy, dipole moment, softness, and hardness were calculated for compounds occupied orbitals (energy gap). It is found that compound e is the most effective corrosion inhibitor, followed by compounds c, and then d with medium efficiency. The (HOMO-LUMO) state was discussed. Also, antibacterial activity of compounds (a–e) against four kinds of bacteria including Escherichia coli, Klebsiella pneumonia, Salmonella, and Staphylococcus aureus was evaluated. Compounds a and b were found highly active against all these types of bacteria, whereas c and e were moderately active against bacteria.