Circularly Polarized Luminescence (CPL)-Active Homo- and Heterostructures by Surface-Catalyzed Secondary Supramolecular Polymerization.

Surface-catalyzed secondary nucleation is well-known in protein aggregation but underexplored in supramolecular polymerization of π-systems. Herein, we report a unique example of multistep secondary nucleation-dominated controlled supramolecular polymerization of an amide-functionalized naphthalene monoimide derivative (O-NMI-1) in a methylcyclohexane:decane mixture, undergoing a stepwise transformation from a metastable particle to crystalline nanorods via intermediate nanotapes over 48 h. The resulting hydrogen-bonded nanorods display enhanced emission, a high quantum yield (34%) and strong circularly polarized luminescence (CPL), revealing an unprecedented correlation between their structural evolution and the time-dependent increment in the CPL intensity, reaching an appreciably high luminescence dissymmetry factor (g) of ∼0.088 in the film state. Contrastingly, the seeded polymerization of O-NMI-1 follows a fragmentation-dominated mechanism, yielding unexpected fragmented nanorods in multi-seeding cycles. Control experiments with a structurally similar analogue (O-NMI-2), lacking a methylene spacer, revealed no CPL, highlighting the spacer's crucial role in controlling the excited-state chiral emission. The contrasting behavior between the two monomers enabled hetero-seeded polymerization of O-NMI-1 nanorods from O-NMI-2 fibrillar seeds, producing CPL-active unique heterostructures under kinetic control from two initial CPL-silent components. The present findings unveil the overlooked impact of secondary nucleation in temporal control of supramolecular chirality and CPL-activity in homo- and heterostructures of supramolecular polymers.