Self-assembled Helical Tetramer Stack of Terrylene Bisimide in Solution and Crystalline State

A terrylene bisimide (TBI) derivative 1 bearing bulky meta-terphenyl imide substituents is shown to self-assemble into helical [1₄] tetramer stacks in solution. Driven by strong dispersion and electrostatic forces, a direct transition from monomers into defined tetramers is already observed in the micromolar concentration range (∼10^-6 M) in methylcyclohexane at room temperature, corresponding to a π-π-interaction strength of ΔG = -40.1 kJ mol^-1 for the respective π-π-stacking interaction between two neighboring TBIs. Upon addition of perylene (P), a further growth of the stacks toward [P^.1₄ ^.P] hexalayers is observed where the guest molecules are stacked at the peripheral positions. In contrast, upon addition of the larger coronene (C), the equilibrium shifts toward 1:2 complexes [C^.1^.C] where each TBI is surrounded by two coronene neighbors. Single crystal X-ray analyses of the pristine [1₄] tetramer stack as well as the [P^.1₄ ^.P] hexalayer stack and the 1:2 trilayer [C^.1^.C] unambiguously confirm the unique stacking arrangements.