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Updated: Jul 31, 2025

Self-assembling Morphologies Obtained from Helical Polycarbodiimide Copolymers and Their Triazole Derivatives
Published on: February 7, 2017
Switchable Double Inversion of Chirality in a Helical Polyelectrolyte
Yang Zhao1,2, Jingfa Yang1,2, Minghua Liu1,2
1Beijing National Laboratory for Molecular Sciences, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, China.
Abstract:
Switchable inversion of chirality between opposite handedness by varying pH is discovered for a histidine pendant polymer, polymethyl (4-vinylbenzoyl) histidinate (PBHis), as demonstrated by the circular dichroism as well as the changes of hydrodynamic radius measured by fluorescence correlation spectroscopy at the single molecular level. The polyelectrolyte is found to take an M-helicity below pH 8.0 and change into P-helicity above pH 8.0. Such helicity further inverses into M-chirality above pH 10.6. All these helical structures with opposite handedness can be switched using pH variations. The mechanism of such a unique phenomenon is attributed to the protonation and deprotonation of the imidazole group and the hydroxide-ion-mediated hydrogen bonding, which determine the mutual orientation between the adjacent side groups under the hydrogen bonds and π-π stacking and therefore the handedness of the helical structure.
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