Superstructures of diketopyrrolopyrrole donors and perylenediimide acceptors formed by hydrogen-bonding and π···π stacking

Synthetic supramolecular systems can provide insight into how complex biological systems organize as well as produce self-organized systems with functionality comparable to their biological counterparts. Herein, we study the assembly into superstructures of a system composed of diketopyrrolopyrrole (DPP) donors with chiral and achiral side chains that can form triple hydrogen bonds with perylene diimide (PDI) acceptors into superstructures. The homoaggregation of the individual components as well as the heteroaggregate formation, as a result of π···π stacking and H-bonding, were studied by variable-temperature UV/vis and CD spectroscopies and electronic structure theory calculations. It was found that, upon cooling, the achiral PDIs bind to disordered DPP stacks, which drives the formation of chiral superstructures. A new thermodynamic model was developed for this unprecedented assembly that is able to isolate the thermodynamic binding parameters (ΔH, ΔS) for all the different noncovalent contacts that drive the assembly. This novel assembly as well as the quantitative model described in this work may help researchers develop complex self-assembled systems with emergent properties that arise as a direct result of their supramolecular structures.