The electronic structure of a series of dibenzofurane and dibenzothiophene derivatives has been studied by means of hybrid density functional theory. The molecular structures of these compounds were obtained through full geometry optimization and then characterized as potential energy surface minima through the pertinent vibrational analysis. The analysis of the frontier orbitals together with the study of aromaticity allows us to make predictions about the reactivity of these molecules and to compare them to the recent findings on carbazole derivatives. Since dibenzofurane, dibenzothiophene, and carbazole are likely to be molecular moieties present in crude oil, their possible role in the formation of asphaltene-like molecules is discussed.