Helicity induction and memory of a lipophilic Brønsted acid-type poly(phenylacetylene) in non-polar solvents.

A novel lipophilic Brønsted acid-type PPA (poly-1-H) bearing a sulfonylphosphoramidic acid moiety, covered with a dynamically axially chiral biphenyl pendant, was synthesized and found to form a preferred-handed helical conformation in non-polar solvents upon complexation with non-racemic amines. This induced helicity was maintained after replacement with achiral amines ("dynamic helicity memory"). In addition, poly-1-H exhibited "static helicity memory" in which the induced helical conformation was maintained in non-polar solvents, even after acidification with a stronger acid without replacement with achiral amines.