Graph-theoretical analysis of tunneling electron transfer in large polycyclic aromatic hydrocarbon networks

Effect of a single nitrogen atom substitution to a number of large polycycl ic aromatic hydrocarbon (PAH) molecules was calculated systematically, and it was found that especially in parallelogram-type PAH abnormal electron tr ansfer (called tunneling electron transfer, TET) was observed. That is, fai rly large amount of pi -electron is withdrawn to an electronegative nitroge n atom from almost the farthest end of a conjugated aromatic hydrocarbon mo lecule, leaving almost no change in the interior of the molecule. This chan ge can be simulated by the Kekule structure counting for subgraphs of the p arent molecule.