Modulating the Macroscopic Helicity of Poly(m-phenylenediamine) by Achiral Monomer Copolymerization

Designing artificial systems to mimic chiral superstructures and exploring how achiral molecules precisely modulate their chirality is crucial to understand the origin of homochirality in nature. Herein, the tunability nature of supramolecular chirality is subtly applied to fabricate robust chiral covalent polymers with controlled macroscopic helicity. When using conventional supramolecular transcription methods to prepare chiral poly(m-phenylenediamine), simply introducing various small amounts of achiral diaminopyridines (DAPs) to copolymerize with m-phenylenediamine (MPD) enables the resulting chiral copolymers with adjustable helical configurations and chiroptical activities in an enantiopure template system. The strong hydrogen bonds between DAPs and the template molecules ((S)/(R)-PhgC(16)) proved to be the driving force for guiding the chiral polymerization mode of MPD. Impressively, the exquisite self-sorting phenomenon is observed by tuning the stoichiometric ratio of DAP and (R)-PhgC(16), where the as-prepared copolymers with opposite helicity can exist simultaneously to form a double network structure and their chiroptical activity can be well regulated. In addition, based on such a copolymerization strategy, a conceptual library of helical functional copolymers is built with editable polymer types including conducting polymers and designable amine-aldehyde condensation-based polymers. This copolymerization-mediated synthetic strategy may facilitate the development of chiral polymers with controlled morphologies and dynamic compositions.

Automated summary

Designing artificial systems to mimic chiral superstructures and investigating the modulation of chirality by achiral molecules is important for understanding the origin of homochirality in nature. In this study, the tunability of supramolecular chirality is applied to fabricate chiral covalent polymers with controlled helicity. By introducing small amounts of achiral diaminopyridines (DAPs) during the copolymerization process, chiral copolymers with adjustable helical configurations and chiroptical activities can be obtained. The hydrogen bonding between DAPs and template molecules is found to be the driving force for the chiral polymerization. Additionally, a library of helical functional copolymers, including conducting polymers and condensation-based polymers, can be built using this copolymerization strategy.