Rational Design of Stable Dianions by Functionalizing Polycyclic Aromatic Hydrocarbons.

Using density functional theory, we have carried out a systematic study of the stability and electronic properties of neutral and multiply charged molecules B C X (n=0, 1, 2; X=H, F, CN). Our main objective is to explore if the replacements of core C atoms and/or H atoms in naphthalene (C H ) can enhance the stability of their dianions. Indeed, we find that the dianions of B C (CN) are more stable than their monoanions with energies of 0.61 eV, 0.57 eV, and 1.97 eV for n=0, 1, 2, respectively. In addition, polycyclic aromatic hydrocarbons become stable as dianions only when H atoms are substituted by more electronegative species. Thus, a rational design approach by tailoring composition and ligands can lead to a new class of organic molecules that are capable of carrying multiple charges.