Controlling hydrogen-bond preferences in bipyridines with competing binding sites

The design and synthesis of a family of supramolecular reagents (SRs) based on ethynyl-spaced substituted bipyridines are described, and their potential use as molecular ‘hubs’ for the predictable construction of binary and ternary co-crystals is explored. Each SR was synthesized in good yields through consecutive Pd-catalyzed Sonogashira cross-coupling reactions. Crystal structures of three binary co-crystals are presented with each structure clearly illustrating how accurate supramolecular assembly control can be achieved by increasing/decreasing the strength of the participating hydrogen-bond interactions.