A Close Look at the Molecular Structure, Prototropic Behavior and Supramolecular Architecture of (E)-4-Bromo-2-[(phenylimino)methyl]-5-methoxyphenol by Spectroscopic, Crystallographic, and Computational Methods

Abstract

In this study, the molecular structure, prototropic behavior and supramolecular architecture of a new Schiff base have been studied in depth using spectroscopic (UV-vis), crystallographic (XRD) and computational (HOMA and DFT) methods. Regarding the molecular structure and prototropy, the XRD, DFT and HOMA results show that the compound exists in phenol-imine form. The HOMA indices for the structural evaluation show that the compound has a pure aromatic structure in solid state. UV-vis spectra of the compound dissolved in four different solvents were investigated in order to determine which tautomeric form of the compound is dominant in the solution. It is found that the compound prefers only phenol-imine form in apolar solvents while both phenol-imine and keto amine forms appear in polar solvents. This is because polar solvent decrease the activation energy, and thus, it becomes possible to observe both forms in the solution. For an energetic approach, the tautomeric conversion between two forms of the compound was investigated by a PES scan process and close energy values were obtained for two tautomers. Investigation of non-covalent interactions underlines the active roles of C–H···O H-bonds and C···Br interactions in constructing the supramolecular network of the compound.