Optically active helical random copoly­(phenylacetylene)­s were prepared from structurally similar monomers, (+)-3-hexadecyl­carbamoyl-5-[((S)-1-phenylethyl)­carbamoyl]­phenyl­acetylene and 3-hexadecyl­carbamoyl-5-(benzyl­carbamoyl)­phenyl­acetylene, under the catalysis of Rh­[C­(C6H5)C­(C6H5)2]­(nbd)­(4-FC6H4)3P (nbd = 2,5-norbornadiene). The chiral amplification followed either normal or abnormal “sergeants-and-soldiers” rule depending on the solvent nature. In apolar solvents (i.e., CHCl3 and THF), contracted cis-cisoid M- and P-helices were selectively induced for the copolymers containing chiral units below or above 74 mol %, respectively. In polar solvent (i.e., CHCl3/CH3OH, 70/30, v/v), a cis-cisoid to cis-transoid transition occurred and stretched M-helices were dominantly formed, the optical activity of which scaled up nonlinearly with increasing chiral component. This unusual phenomenon was rationalized by the distinct competing interactions between the vicinal chiral/achiral and chiral/chiral unit pairs in the contracted and stretched helices according to the modified Ising model. It offers a promising design strategy to control macromolecular helicity.

Allostery can regulate protein self‐assembly which further affects biological activities, and achieving precise control over the chiral suprastructures during self‐assembly remains challenging. Herein, to mimic the allosterical nature of proteins, the poly(phenylacetylene) block copolymers PPA‐b‐PsmNap with the dynamic helical backbone were synthesized to investigate their conformational‐transition‐induced self‐assembly. As the helical conformation of the block PsmNap spontaneously transforms from cis‐transiod to cis‐cisoid, the decreasing solubility of PsmNap blocks in THF induced self‐assembly of PPA‐b‐PsmNap. The self‐assembly structures of copolymers can sequentially evolve from vesicles to nanobelts to helical strands during the process of conformation transformation. The screw sense of final helical strands was strictly correlated to the helicity of the block PsmNap. This is helpful to understand the mechanism of allostery‐modulated self‐assembly.

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