Controlling the structural transition between well-defined architectures found in living system is essential in polymer chemistry as well as material science. Herein, the reversible conformational switch of a non-natural polypeptide with an aromatic ring (2,6-naphthalene spacer) on its peptide backbone, referred to as an arylopeptide, between two distinct well-defined helical structures (extended 31 -helix and contracted 41 -helix) using side chain solvation is demonstrated. The folding selectivity of the arylopeptide and found that the affinity between the solvent and side chains is an essential factor for determining the global structure is investigated. A thermoresponsive arylopeptide bearing oligoether groups (─(CH2 CH2 O)9 CH3 )) on the side chain is designed, which exhibited unique lower critical solution temperature behavior and converted from the 31 to the 41 -helix depending on the temperature. Furthermore, the solvent affinity of the entire polymer by combining substituents (─(CH2 CH2 O)3 CH3 and ─C12 H25 ) with different properties on the side chains to achieve a spring-like expansion-contraction system that allows interconversion between 31 - and 41 -helices is adjusted.
Keywords: asymmetric polymerization; helix; non-natural polypeptides; solvation; stimuli-responsible polymers.
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