Topological description of the non-covalent interactions present within 2-(2-Hydroxyphenyl)benzothiazole analogues: An “Atoms in Molecules” investigation

Abstract

“Atoms in Molecules” formalism has been exploited to highlight the non-covalent interactions present within the molecular frameworks of a series of compounds structurally analogous to 2-(2-Hydroxyphenyl)benzothiazole and to critically assess the energetics of the interaction lines towards the conformational preference as well as the global stabilization of the said structures. Moreover, for a comprehensive scrutiny of the regulatory role of the aromatic stabilization of the rings present within the frameworks in governing the preferred conformation as well as to study its modulations in the presence of the non-covalent communications; Nucleus independent chemical shift (NICS) descriptor has also been employed. The hydrogen bonds associated with the Closed conformations of the concerned structures are distinguished by closed shell synergy with a credible degree of covalency and the corresponding energetics is found to have no discernible dependence on the substitutions in the aromatic nuclei. On the other hand, the Open conformations are found to have either an H····H or an N····H interaction lines; topologically identified as closed-shell interaction. For the systems with an N12 substitution (vide Scheme 1), the difference between the energies of the Closed and the Open conformations is found to significantly decrease which has been attributed to the enhanced stability of the N12 and the Hd atoms in the Open conformations, corroborated by a marginal increase in the aromaticity of the allied Open conformations as compared to the Closed conformations.