Unravelling the potential of sigma hole-assisted co-crystallization: Highlighting recent developments

Abstract

In the past several decades, the field of cocrystal engineering has developed into a vital research topic in supramolecular chemistry, holding the foremost scope in crystal engineering, medicinal chemistry, materials chemistry, and the pharmaceutical industry. The medium of cocrystallization has been through the classic non-covalent interactions. However, cocrystallization through sigma hole (σ-hole)-based modern interactions is a breakthrough in crystal engineering. This σ-hole mediated non-covalent interaction uniquely contributes to supramolecular chemistry through different subgroups viz halogen bonding (XB), chalcogen bonding (ChB), pnictogen bonding (PnB), and tetrel bonding (TB). Despite much potential, chalcogen bonding, pnictogen bonding, and tetrel bonding are yet at an infancy stage compared to halogen bonding. Hence, we attempted to address the great potential of these non-covalent interactions (intra- and inter-molecular) and enlighten the ChB, PnB, and TB, as their outstanding contribution to the supramolecular domain needs to be communicated. Through this account, we promote these cooperative σ-hole-based interaction synthons as attractive toolboxes in supramolecular chemistry by addressing the strength and directionality of σ-hole potential, the role of steric hindrance, different modes of characterizations, application in distinct fields, etc. We hope this work will be the medium of a new direction in advancing σ-hole-assisted interactions in different research areas. Also, chalcogen, pnictogen, and tetrel bonding could get out of the shadow of halogen bonding and get their recognition in supramolecular chemistry.