A theoretical study of the global and local electrophilicity, nucleophilicity, polarizability and QTAIM theory for calix[4]arene-gas interaction

The calix[4]arene molecule, abbreviated as CX[4], is known by the four phenolic groups and a hydrophobic cavity able to enclose small molecules. The interactions between CX[4] and NO(3,) NO(2), CO(2), and N(2) gas molecules have been studied. These guest species are placed inside and outside the cavity of the host molecule CX[4]. The formation of H-bonding has been deeply discussed based on the infrared spectrum and the polarizability analysis. Global and local indices have been calculated for a series of gas (NO(3,) NO(2), CO(2) and N(2)) in interaction with the CX[4] molecule to explain the electrophilic or nucleophilic activations in endo-vs. exo-cavity interaction zone. As expected, there is a correlation between the proposed global electrophilicity and global nucleophilicity together for an explanation of the chemo-selectivity region. Finally, the topological parameter analyses of the host-guests interactions have been estimated by using DFT calculations.