title: Aromatic Character of Irregular-Shaped Nanographenes.
abstract: We found that the Clar sextet formula with the maximum number of sextet rings cannot always be defined meaningfully for large irregular-shaped PAHs. It is true that edge structure is always a primary determinant of the PAH aromaticity pattern. In large PAH molecules, every edge structure modifies the aromaticity pattern near the edge, but its influence fades on going away from the edge. It follows that different textures of the aromaticity pattern appear near different edges. As a result, the entire aromaticity pattern does not always match with a single Clar formula or a single weighted superposed Clar formula. Such an unusual feature of aromaticity patterns could not have been observed distinctly if we had not explored the aromaticity patterns of large irregular-shaped PAH molecules systematically. We used the superaromatic stabilization energy (SSE) as a local aromaticity index, which is the only index of this kind not disturbed by the aromaticity of adjacent benzene rings.
authors.affiliation: Department of Chemistry, Faculty of Science, Shizuoka University , Oya, Shizuoka 422-8529, Japan.
authors.forename: Naoko
authors.initials: N
authors.lastname: Nishina
authors.affiliation: Department of Environmental and Life Sciences, School of Food and Nutritional Sciences, University of Shizuoka , Yada, Shizuoka 422-8526, Japan.
authors.forename: Masakazu
authors.initials: M
authors.lastname: Makino
authors.affiliation: Department of Chemistry, Faculty of Science, Shizuoka University , Oya, Shizuoka 422-8529, Japan.|Department of Environmental and Life Sciences, School of Food and Nutritional Sciences, University of Shizuoka , Yada, Shizuoka 422-8526, Japan.
authors.forename: Jun-ichi
authors.initials: J
authors.lastname: Aihara