Structure–Property Relationship of Supramolecular Rotators of Coronene in Charge-Transfer Solids

Single crystals of charge-transfer (CT) complexes composed of the polyaromatic hydrocarbon, coronene, as an electron donor (D) and 7,7,8,8-tetracyanoquinodimethane (TCNQ) analogues as electron acceptor (A) were obtained. Elucidation of crystal structures of CT complexes enables a systematic investigation of dynamic properties of coronene molecules lying in different types of crystalline environments. Solid-state 2H NMR spectra of CT complexes formed with deuterated coronene confirmed the in-plane 6-fold flipping motion of the coronene molecules. The dihedral angle between adjacent coronene and TCNQ analogue within the DA-type alternating π-column is closely correlated with the dynamic properties, such as rotational rate and activation energy. Side-by-side intermolecular hydrogen-bonding also seems to have an effect in ways that lead to the suppressed rotation. These findings would provide an initial step toward the selection, design, and engineering of counter components of supramolecular rotators in the CT solids.