Effect of internal oxygen substituents on the properties of bowl-shaped aromatic hydrocarbons

Internally substituted pi-systems have remained somewhat underexplored in contrast to their peripherally functionalized counterparts. In this study, we compare a bowl-shaped aromatic hydrocarbon with internal methoxy groups to related derivatives with hydrogen, methyl, and anisyl groups, evaluating their electron-accepting properties, electronic absorption spectra, and fullerene-binding behavior. The methoxy-substituted derivative exhibits enhanced electron-accepting properties and positively shifted electrostatic potential mapping on its concave surface due to the inductive effect of the oxygen atoms. The sigma* orbitals of the internal C-O bonds participate in pi-conjugation to change the absorption properties of the bowl-shaped pi-skeleton. As hydrocarbons internally substituted with oxygen are key fragments of graphene oxide, these results can be expected to aid the understanding of the structure-property relationships in graphene oxide. Furthermore, internal substitution with oxygen atoms decreases the efficiency of fullerene-binding, thus affording fundamental insights into the design of advanced fullerene-receptors.