Heterogeneously catalyzed supramolecular polymerization: essential roles of nucleation and fragmentation-induced autocatalysis in chiral transfer

Abstract

The complexity of multi-component molecular assembly demands precise control strategies to enhance both efficiency and selectivity. Heterogeneous nucleation and the autocatalytic secondary pathway, as key regulatory strategies, have attracted widespread attention for their crucial roles in crystal growth and amyloid protein aggregation. Here, we apply a heterogeneous nucleation strategy to supramolecular polymer systems and report the first direct observation of surface-enrichment-induced primary nucleation and a spontaneous fragmentation-driven autocatalytic secondary process. A heterogeneous nucleating agent promotes primary nucleation, facilitating supramolecular chiral induction. The resulting chiral polymers undergo a catalytic cycle of fragmentation and re-growth at their termini, with the fragments also acting as seeds for nucleation and growth. These pathways play a crucial role in the polymerization process and are essential for chiral transfer and asymmetry amplification, enabling the achievement of maximum enantioselectivity with as little as 0.5% molar equivalent of the heterogeneous nucleating agent. Furthermore, we reveal the existence of an optimal equivalent in their catalytic kinetics, arising from a surface assembly mechanism. In this mechanism, monomers adsorbed on the surface of the heterogeneous nucleating agent assemble with those in solution, rather than through surface diffusion and assembly. This process resembles the surface-catalyzed Eley–Rideal mechanism. Our study highlights the potential of heterogeneous nucleation as an effective strategy for controlling supramolecular polymerization and offers new insights into its underlying mechanism.