Superhelices with Designed Helical Structures and Temperature-Stimulated Chirality Transitions

The synthesis of multicomponent superhelices with determined chirality has been realized. By adding water to polymer solution in organic solvents (tetrahydrofuran/N,N′-dimethylformamide, THF/DMF), poly­(γ-benzyl l-glutamate)-block-poly­(ethylene glycol) (PBLG-b-PEG) are able to pack orderly around the surface of PBLG homopolymer bundles with designed helical structures, e.g., right-handed and left-handed, depending on THF/DMF ratio and temperature. A systematic investigation leads to the construction of a temperature–organic solvent composition phase diagram. Before the organic solvents were totally removed, the chirality of the assemblies can be reversibly switched using temperature stimulus. This temperature-stimulated chirality transition of polypeptide superhelices is unprecedented. Circular dichroism (CD) experiments indicated that the packing mode of pending phenyl groups from PBLG chain is responsible for the determination of the helical morphologies.