Theoretical study of microscopic molecular structure of helicenebisquinone aggregates

Molecular level studies of intermolecular interaction forces and microscopic structures are essential to understand molecular aggregates and self-assembly phenomena. Recently, fibrous helicenebisquinone (HBQ) aggregates have been of great interest because of their strongly enhanced nonlinear optical (NLO) properties. The intermolecular interaction force and microscopic structure of HBQ aggregates were proposed to be donor-acceptor interaction and a columnar stack, respectively. However, our present study suggests that the intermolecular interaction force of HBQ aggregates would be the paired hydrogen bonding between quinone moieties, and its molecular structure would be one-dimensional hydrogen bond chain. Though the information from the experiments is somewhat limited, our prediction of molecular level structure is consistent with the experimentally observed macroscopic structure.