Boosting the Host–GuestBinding by Programmingthe Curvature in Geodesic Nanoribbons

The curvature of an aromatic system is an essential parameter that can be used to program the self-assembly and host–guest complementarity in geodesic polyarenes. However, the challenging synthesis of curved aromatics impedes exploration of the related effects on the binding properties. The design and synthesis of a polyarene with programmed curvature fitting to C₆₀ by a stepwise introduction of five-membered rings are presented to solve this challenge. Among several methods explored, the route utilizing cyclodehydro­fluorination proved to be the most successful, in terms of the highest product yield. The binding studies suggest that fine-tuning the curvature in acyclic systems leads to a dramatic increase in affinity, embedding specific binding modes and selectivity, as revealed from the comparative studies with C₆₀ and C₇₀. Experimental and theoretical investigations with curved polyarenes of different sizes show that the buried surface area upon binding has a linear correlation with the binding energies. The curvature complementarity appeared to play a decisive role in achieving selective recognition of C₇₀ via the formation of a 2:1 complex along the major axis with an overall constant of 10⁸ M^–2 and positive cooperativity. The developed nanoribbons bearing the curvature of C₆₀ is the first all<b>-</b>carbon host showing binding affinities for fullerenes that are comparable with macrocyclic [10]CPP. The obtained data pave the way for understanding the properties of geodesic polyarenes and the design of new self-assembled materials based on fullerenes, nanotubes, and other curved structures.