Chiral Amine-Induced Assembly of Toroidal Structures with a Carboxylic Acid-Functionalized, Polymerizable Macrocyclic Diacetylene

Abstract

Forming toroidal structures through self-assembly strategies on a small scale poses significant challenges due to the bending energy barriers involved. Herein, we present the chiral amine-induced fabrication of toroidal structures assembled with a carboxylic acid-functionalized macrocyclic diacetylene (MCDA-COOH/PEA). The formation of microtoroids follows an interesting, heat-induced morphological transition pathway, starting from seeds to the sphere and eventually forming stable microtoroids. The structural arrangements of the microtoroids were analyzed through spectroscopic techniques and X-ray diffraction. These microtoroids further undergo topochemical polymerization upon UV light irradiation, resulting in a blue-phase polymeric PDA structure. This study demonstrates the role of chiral control, intermolecular interactions, and molecular rearrangement via energy minimization in a heat-induced morphological transition pathway. This process induces curvature between adjacent building blocks, promoting the formation of stable toroidal structures with minimized free energy. This study presents a promising self-assembly approach to constructing highly organized functional architectures.