Accessing a Hidden Pathway to Supramolecular Toroid through Vibrational Strong Coupling

Control over specific intermolecular interactions is crucial to the formation of unique supramolecular assemblies. Recently, vibrational strong coupling (VSC) has emerged as a new tool for manipulating these interactions. Although VSC shows promise for controlling molecular assembly, it has not yet demonstrated the capability to open a pathway for creating structures that are inaccessible by conventional assembly methods. Here, we used VSC to control the transformation process of a naphthalenediimide supramolecular polymer induced by a click reaction. The supramolecular polymers with reactive ethynyl groups undergo a transformation from long fibers to thick fibers upon induction by an amino-yne click reaction in the absence of VSC. Under VSC of the C–H stretch, the click reaction within supramolecular polymers is accelerated; no such acceleration occurs in the reaction of individual monomers, suggesting that the acceleration is due to changes in the assembled structures. Indeed, applying the VSC to the C–H stretch uniquely altered the morphological transformation process, leading to the formation of metastable toroids instead of thick fibers. Notably, the molecular assembly cannot be directed toward a toroidal structure without a VSC. Theoretical simulations suggested that slipped packing configurations in the supramolecular polymers form the curvature necessary for toroidal structures. The experimental results, supported by theoretical simulations, suggest that intermolecular interactions among naphthalenediimide molecules are modified under VSC, leading to a slipped packing configuration of the toroidal assembly. These findings link the VSC-induced modulation of intermolecular interactions to structural outcomes, establishing VSC as a tool for manipulating molecular assembly beyond traditional assembly methods.