Shedding Light on the Nature of Host-Guest Interactions in PAHs-ExBox⁴⁺ Complexes

Host-guest (HG) systems formed by polycyclic aromatic hydrocarbons and ExBox⁴⁺ 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 ExBox⁴⁺ (1) and polycyclic aromatic hydrocarbons (PAHs) (2-12) 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⊂ExBox⁴⁺ 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.