Kinetic Pathway Selection in Supramolecular Polymerization via Transient Helical Inversion

초록

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.

키워드