Recently synthesized p-extended symmetrical tetraoxacirculenes that exhibit electroluminescent properties were calculated at the density functional theory (DFT) level using the quantum theory of atoms in molecules (QTAIM) approach to electron density distribution analysis. Nucleus-independent chemical shift (NICS) indices were used to characterize the aromaticity of the studied molecules. The tetraoxacirculene molecules were found to consist of two antiaromatic perimeters (according to the Hückel "4n" antiaromaticity rule) that include 8 and 24 p-electrons. Conversely, NICS calculations demonstrated the existence of a common p-extended system (distributed like a flat ribbon) in the studied tetraoxacirculene molecules. Thus, these symmetrical tetraoxacirculene molecules provide examples of diatropic systems characterized by the presence of induced diatropic ring currents.
Journal of Molecular Modeling, 2013, Vol 19, Issue 2, p. 847-850