Scrutinizing the two new o-hydroxy Schiff bases from the point of tautomeric behavior and non-covalent interactions (H-bond, Br⋯Br, π⋯π and C[sbnd]H⋯π) in their supramolecular architectures

Abstract

Two new Schiff bases, (E)-4,6-dibromo-2-[(5-chloro-2-methylphenylimino)methyl]-3-methoxyphenol (1) and (E)-4-bromo-2-[(4-bromophenylimino)methyl]-5-methoxyphenol (2), have been investigated by focusing on the prototropy-related-changes in the geometric parameters, the molecular planarity and the way of crystal packing. X-ray diffraction (XRD), density functional theory (DFT), Hartree-Fock theory (HF) and Møller–Plesset perturbation theory (MP2) and harmonic oscillator model of aromaticity (HOMA) studies show the preference of phenol-imine form by the compounds. The crystal packings of the compounds have been studied in detail by noting the importance of the substituent type and position in regulating the non-covalent interactions, thus, the formation of supramolecular networks. The results underline the fact that the halogen atoms of high polarizability and their presence in the appropriate position dominate the construction of supramolecular structure in Schiff bases.