Architecting a Bismacrocycle through a Single C-C Bond Connection

The covalent linkage of preformed supramolecular entities represents a powerful yet synthetically challenging strategy for constructing sophisticated functional systems, crucial for advances in enzyme mimicry, catalysis, and materials. Addressing the core difficulty of precise, site-selective coupling, we report a direct one-step C-C coupling of carbazole-based macrocycles 2 under Scholl reaction conditions to afford bismacrocycle 1. Interestingly, when using the smaller ring precursor 4 under similar reaction conditions, we obtain the intermolecular dehydrogenative product 3. DFT computations provide insight into the distinct formation pathways of monomacrocycle 3 and bismacrocycle 1. Moreover, we investigated the photophysical properties of compounds 1-4, confirming that all are suitable hosts for C₇₀, with their binding constants determined. Notably, bismacrocycle 1 demonstrates exceptional photocatalytic activity for debrominative borylation, outperforming other macrocycles (2-4) in catalytic efficiency. Finally, we also examined the anticancer activities of these newly synthesized macrocycles. Collectively, this work provides a versatile synthetic strategy for a complex bismacrocycle and establishes its significant dual potential as a selective host, a powerful photocatalyst, and a photocytotoxic anticancer candidate.