Structural, Computational and in Silico Studies of Schiff Bases Derived from 2,3-Dihydroxybenzaldehyde and Molecular Structure of Their Zwitterionic Forms

Abstract

Two novel Schiff bases, 3-{(E)-[(2-hydroxy-5-methylphenyl)imino]methyl}benzene-1,2-diol (SBPC) and 3-{(E)-[(3-hydroxyphenyl)imino]methyl}benzene-1,2-diol (SB3A), were synthesized by the condensation of 2,3-dihydroxybenzaldehyde with 2-amino-4-methylphenol and 3-aminophenol, respectively. The Schiff bases were characterized using elemental microanalysis, NMR, IR, and UV–visible spectroscopy, and single crystal X-ray diffraction analysis (XRD). Density functional theory method was used for computing molecular parameters and some of these were compared with experimental data. The X-ray diffraction data reveal that SBPC crystallized in the orthorhombic space group P2<inf>1</inf>2<inf>1</inf>2<inf>1</inf> with Z = 4, while SB3A crystallized in the monoclinic space group C2/c with Z = 8. The C[sbnd]O and C[sbnd]N interatomic distances in both compounds lie between single and double bond, which confirm their existence in zwitterionic form. Docking studies identified SB3A and SBPC as potential inhibitors of four essential antibacterial targets. © 2019 Elsevier B.V.