Pathway Complexity in Supramolecular Copolymerization and Blocky Star Copolymers by a Hetero-Seeding Effect.

This study unravels the intricate kinetic and thermodynamic pathways involved in the supramolecular copolymerization of the two chiral dipolar naphthalene monoimide (NMI) building blocks ( and ), differing merely by a single heteroatom (oxygen vs sulfur). exhibits distinct supramolecular polymerization features as compared to in terms of its pathway complexity, hierarchical organization, and chiroptical properties. Two distinct self-assembly pathways in occur due to the interplay between the competing dipolar interactions among the NMI chromophores and amide-amide hydrogen (H)-bonding that engenders distinct nanotapes and helical fibers, from its antiparallel and parallel stacking modes, respectively. In contrast, the propensity of to form only a stable spherical assembly is ascribed to its much stronger amide-amide H-bonding, which outperforms other competing interactions. Under the thermodynamic route, an equimolar mixture of the two monomers generates a temporally controlled chiral statistical supramolecular copolymer that autocatalytically evolves from an initially formed metastable spherical heterostructure. In contrast, the sequence-controlled addition of the two monomers leads to the kinetically driven hetero-seeded block copolymerization. The ability to trap in a metastable state allows its secondary nucleation from the surface of the thermodynamically stable spherical "seed", which leads to the core-multiarmed "star" copolymer with reversibly and temporally controllable length of the growing "arms" from the "core". Unlike the one-dimensional self-assembly of and its random co-assembly with , which are both chiral, unprecedentedly, the preferred helical bias of the nucleating fibers is completely inhibited by the absence of stereoregularity of the "seed" in the "star" topology.