Intermolecular Toroidal Conjugation: Circularly Stacked 16 π‐Planes Formed by Supramolecular Assembly Enabling Cyclic Charge and Energy Delocalization

Abstract Toroidal conjugation is a unique mechanism for charge and exciton delocalization via through‐space overlap among circularly stacked π‐orbitals, but the examples have been limited to intramolecular phenomena, where π‐planes are arranged around a hub molecule. In this study, we extend this concept to intermolecular phenomena and provide strong evidence for intermolecular toroidal conjugation in designed systems, in which a circular π‐stacked array is formed by molecular self‐assembly. X‐ray single‐crystal analysis unequivocally revealed a toroidal array of 16 π‐planes formed by the supramolecular dimerization of phthalocyanines substituted with eight pillar‐like diazapentacenes interdigitating their π‐pillars. The experimentally determined interplanar distances in the toroidal π‐stacking array were close enough to realize through‐space conjugation. Various steady‐state and time‐resolved spectroscopies, supported by theoretical calculations, indicated the possibility of positive charge migration within the toroidal π‐stacking array in the cationic and photoexcited states.