N, N-Bis (2,4-dihydroxy benzaldehyde) benzidine: Synthesis, characterization, DFT, and theoretical corrosion study

Abstract

In this work, a new compound, N, N-Bis (2,4-dihydroxy benzaldehyde) benzidine (III), was synthesized by utilizing acetic acid-mediated condensation of two reactants, benzidine (I) and 2,4 dihydroxybenzaldehyde (II). The synthesis method involved combining two reactants (I) and (II) in an acetic acid solution which formed a new compound that was isolated, purified, and confirmed. The structure of the molecule (III) was experimentally characterized using FT-IR (Fourier Transform Infrared Spectroscopy), as well as 1H and 13C NMR (Nuclear Magnetic Resonance) spectroscopy. To further investigate the structure (III), Density Functional Theory (B3LYP/cc-pVDZ) was used to theoretically calculate the ideal molecular structure, its vibrational frequencies, and the chemical shifts of its 1H and 13C NMR spectroscopic signals. The agreement between the theoretical and experimental spectroscopic results confirmed the validity of the synthesized molecule's structure. Furthermore, the dipole moment (µ), hardness (ɳ), softness (σ), electronegativity (χ), electrophilicity index (ω), nucleophilicity index (ε), and chemical potential (Pi) of the compound were examined to explore their correlation with corrosion inhibition efficiency. By analyzing the transferred electrons, it was possible to gain insight into the reaction between the iron surface and organic molecules. The results suggested that the corrosion inhibitors had a positive affiliation with the quantum chemical parameters processes, which indicated that it was possible to predict the performance of the corrosion inhibitors without having committed to any actual tests or experiments.