Controlled Supramolecular Self‐Assembly Pathways by Intramolecular Rotation of D–A Molecular System toward the Signal Differentiation Detection of Toxic Vapors

Abstract Revealing the structural evolution mechanisms of supramolecular self‐assembly can facilitate the exploitation of new self‐assembly pathways and various functional materials. Here, this work reports a unique intramolecular rotation‐induced structural evolution of supramolecular assemblies from a metastable state to a thermodynamically stable state using a twisting D–A molecule. These self‐assemblies are applied to the signal differentiation detection of toxic dimethylsulfide (DMS) vapors. The F161BT monomer of the inactive state is trapped in off‐pathway metastable nanospheres, which can disassemble and induce the transformation of the F161BT monomer into an active state by crossing the energy barrier. Subsequently, the active monomer goes through the processes of nucleation and elongation, forming thermodynamically stable on‐pathway microribbons. Adding seeds can accelerate the molecular conformational transformation, generating microribbons with controlled lengths. Opposite fluorescent responses are obtained when exposing the two aggregates to the DMS vapors, allowing the sensitive detection of DMS with enhanced selectivity, which offers tremendous potential in practical applications.