Reversible Transformation of a One-Handed Helical Foldamer Utilizing a Planarity-Switchable Spacer and <i>C</i>₂‑Chiral Spirobifluorene Units

Polymeric quaterthiophenes containing optically active <i>C</i>₂-chiral spirobifluorene skeletons were synthesized as a new type of helical foldamers, and their higher-order structures were investigated. Oxidization of quaterthiophene moieties caused the spacer units to be in planar structure, leading the conformation of the polymer to be a coil-shaped, rigid helix. This transformation was reversibly performed