Shedding Light on the Nature of Host–Guest Interactions in PAHs-ExBox<sup>4+</sup> Complexes

Host–guest (HG) systems formed by polycyclic aromatic hydrocarbons and ExBox<sup>4+</sup> are suitable models to gain a deeper understanding of π–π interactions, which are fundamental in supramolecular chemistry. The physical nature of HG interactions between ExBox<sup>4+</sup> (<b>1</b>) and polycyclic aromatic hydrocarbons (PAHs) (<b>2</b>-<b>12</b>) is investigated at the light of the energy decomposition (EDA-NOCV), noncovalent interactions (NCI), and magnetic response analyses. The EDA-NOCV results show that the dispersion forces play a crucial role in the HG interactions in PAHs⊂ExBox<sup>4+</sup> complexes. The HG interaction energies are dependent on both the size of the PAH employed and the number of π-electrons in the guest molecules. The parallel face-to-face arrangement between HG aromatic moieties is also fundamental to maximize the dispersion interaction and consequently for the attractive energy which leads to the inclusion complex formation.