Unusual Non-Kasha Photophysical Behavior of Aggregates of Push–Pull Donor–Acceptor Chromophores

Unlike the Frenkel exciton model, the essential state model (ESM) for aggregates of donor–acceptor (DA) chromophores accounts self-consistently for the effect of the reaction field on the ground and excited states of the individual chromophores, an effect that can lead to divergences from Kasha’s H- and J-aggregate classification schemes for highly polarizable molecules. In this work, two slip-stack dimer geometries of DA chromophores are...