Theoretical study of π-hole bonding

Abstract

Non-covalent π-hole interactions have been of great scientific interest in recent years given their contribution to the formation of crystalline structures. Several studies have recently been conducted in order to comprehend and characterize such interactions. This work aims to understand the nature of π-hole contacts in lactam crystalline structures, since they are molecules known for their key role in the field of medicine and antibiotics. This project has carried out both a structural and a theoretical analysis of such interactions for various lactam systems, both experimental and computational model based. A first search in the Cambridge Structural Database (CSD) has given us a first notion of the interaction nature and possible contributions involved in it, such as the orbital contribution. Analyses using Density Theory Functional (DFT) and Natural Bond Orbital (NBO) calculations have allowed us to see the orbital contribution implicated in the π-hole contact and studies using Molecular Electrostatic Potential (MEP) and Atoms In Molecules (AIM) calculations have shown us the electrostatic contribution present in such interaction. From the data recollected it has been possible to see how these interactions present bond values that are not negligible in terms of the formation of crystalline structures. It has also been observed that their nature is not merely electrostatic because, despite being small, the orbital contribution governs some interaction parameters such as the attack angle between the donor atom and the acceptor atom