Physicochemical properties of the three-cavity form of calix[n = 4, 6, 8]aren molecules: DFT investigation

The shape, size and diameter of the cavities are one of the main factors which control the interactions of the calix[n]arene molecules with cation, anion or neutral guests in sensor applications. In this work, vibrational spectroscopy analysis, molecular electrostatic potential (MEP) surface, atom in molecules (AIM) and thermochemical properties were used to check the reorganizations of hydrogen bonds in such cavity shape for the improvement of physical proprieties of CX[n] molecules. We have demonstrated that the hydrogen bonds O···H and the angles O–H···O of CX[n = 4, 6, 8] play the role of the moderator or modifier of the cavity. MEP topography reveals that the cavity form of CX[8] is less hydrophilic as compared to those of CX[4] cavity. The QTAIM theory showed that CX[4] and CX[8] has a more symmetric and well-organized cavity than CX[6]. It was also shown that the hydrogen bond enhanced the topographic parameters in CX[n] at the lower edge levels.