Chiral Amplification in Macromolecular Helicity Assisted by Noncovalent Interaction with Achiral Amines and Memory of the Helical Chirality

Poly[(4‐carboxyphenyl)acetylene] (poly‐ 1 ) exhibits an intense induced circular dichroism (ICD) in the UV‐visible region upon complexation with excess ( R )‐1‐(1‐naphthyl)ethylamine (( R )‐ 2 ), owing to the formation of a predominantly single‐handed helical conformation of the polymer backbone. In the presence of a small amount of ( R )‐ 2 , poly‐ 1 showed a very weak ICD due to the lack of a single‐handed helical conformation. However, we have found that the co‐addition of the excess bulky, achiral 1‐naphthylmethylamine ( 5 ) with a small amount of ( R )‐ 2 caused a dramatic increase in the ICD magnitude, comparable to the full ICD induced by excess ( R )‐ 2 . This indicates that an almost single‐handed helix can be induced on poly‐ 1 upon complexation with a small amount of ( R )‐ 2 assisted by achiral 5 . Furthermore, the induced single‐handed helical poly‐ 1 could be successfully memorized by the replacement of ( R )‐ 2 and 5 with achiral 2‐aminoethanol or n ‐butylamine.