Secondary Structure Control and Functionalization of Synthetic Polymers by Ladderization

Biomacromolecules, such as DNA and proteins, form characteristic secondary structures, represented by α-helix and β-sheets, which are further assembled into tertiary and quaternary structures through specific intra- and intermolecular interactions. Such higher-order structures play a key role in the expression of the sophisticated biological functions. While advances in polymerization technologies have made it possible to precisely control the primary structures of synthetic polymers, the design and construction of higher-order structures, even secondary structures, remains a major challenge in polymer science. Recently, the author's group has developed a novel synthetic methodology called “defect-free ladderization” and combined it with “chiral molecular design” to realize the tailored construction of diverse secondary structures to meet specific functional requirements. In this article, we present our recent results with emphasis on the efficient synthesis of defect-free ladder polymers with specific secondary structures via alkyne benzannulations and the development of functional materials based on the rational design of artificial secondary structures. We anticipate that these results will provide new directions for advancing the field of organic synthesis and polymer science.