Kinetic Pathway Selection in Supramolecular Polymerization via Transient Helical Inversion

Abstract

Designing the organization of supramolecular systems with high-precision self-assembly along diverse pathways is a crucial strategy for optimizing functional properties. However, achieving such control remains a significant challenge in the field. Here, we report the selective pathway dynamics of platinum(II) terpyridine-based complexes with (R)-chiral side chains, which exhibit three distinct states (Agg-A, -DH, and -SH) in different pathways during the self-assembly process. The assembly is initiated by the formation of metastable helical structures (Agg-A) with concentration-dependent handedness, which subsequently undergo a transient helical inversion. Kinetic evaluations reveal that Agg-A diverges into two distinct pathways governed by the thermal energy landscape. At 308 K, Agg-A acts as an on-pathway intermediate, forming a kinetically trapped superhelix (Agg-DH) via interfiber interactions. Conversely, at 333 K, Agg-A serves as an off-pathway intermediate, directly transforming into a thermodynamically stable single helix (Agg-SH). Ultimately, all metastable and kinetically trapped states converge toward the thermodynamically favored Agg-SH. Notably, this structural divergence enables the selective regulation of chiroptical functions. Specifically, the thermodynamically stable Agg-SH state exhibits a distinct circularly polarized luminescence (CPL) signal, whereas the kinetically trapped Agg-DH state displays a negligible CPL response. Furthermore, we successfully demonstrated precise pathway control utilizing seeded living supramolecular polymerization. This study highlights how morphological evolution driven by transient helical inversion and intermolecular Pt–Pt interactions can be utilized as a rational design strategy to program the specific optical functions of chiral supramolecular materials.