Exploring the supramolecular chemistry of cyclopropeniums: halogen-bonding-induced electrostatic assembly of polymers.

Exploring new noncovalent synthons for supramolecular assembly is essential for material innovation. Accordingly, we herein report a unique type of cyclopropenium-based supramolecular motif and demonstrate its applications to polymer self-assembly. Because of the "ion pair strain" effect, trisaminocyclopropenium iodides complex strongly with fluoroiodobenzene derivatives, forming stable adducts. Crystal structure analysis reveals that halogen-bonding between the iodide anion and the iodo substituent of the fluoroiodobenzene is the driving force for the formation of these electrostatically complexed adducts. Such halogen-bonding-induced electrostatic interactions were further successfully applied to drive the assembly of polymers in solution, on surfaces, and in bulk, demonstrating their potential for constructing supramolecular polymeric materials.