Probing the Solvent-Assisted Nucleation Pathway in Chemical Self-Assembly

TLDR

Hierarchical self‑assembly is a powerful strategy for creating molecular nanostructures, yet its mechanistic details remain poorly understood. The authors spectroscopically monitored nucleation of p‑conjugated molecules into helical fibrillar structures and showed that an organized solvent shell rigidifies aggregates and directs further bundle or gel assembly. The data reveal a nucleation‑growth pathway with high cooperativity and a helical transition in the nucleating species, driven by solvent‑mediated aggregation.

Abstract

Hierarchical self-assembly offers a powerful strategy for producing molecular nanostructures. Although widely used, the mechanistic details of self-assembly processes are poorly understood. We spectroscopically monitored a nucleation process in the self-assembly of p-conjugated molecules into helical supramolecular fibrillar structures. The data support a nucleation-growth pathway that gives rise to a remarkably high degree of cooperativity. Furthermore, we characterize a helical transition in the nucleating species before growth. The self-assembly process depends strongly on solvent structure, suggesting that an organized shell of solvent molecules plays an explicit role in rigidifying the aggregates and guiding them toward further assembly into bundles and/or gels.