Macromolecular Helicity Inversion of Poly(phenylacetylene) Derivatives Induced by Various External Stimuli

摘要

Unique macromolecular helicity inversion of stereoregular,optically active poly(phenylacetylene)derivatives induced by external achiral and chiral stimuli is briefly reviewed.Stereoregular,cis-transoidal poly(phenylacetylene)s bearing an optically active substituent,such as(1R,2S)-norephedrine(poly-1)and beta-cyclodextrin residues(poly-2),show an induced circular dichroism(ICD)in the UV-visible region of the polymer backbone in solution due to a predominantly one-handed helical conformation of the polymers.However,poly-1 undergoes a helix- helix transition upon complexation with chiral acids having an R configuration,and the complexes exhibit a dramatic change in the ICD of poly-1.Poly-2 also shows the inversion of macromolecular helicity responding to molecular and chiral recognition events that occurred at the remote cyclodextrin residues from the polymer backbone;the helicity inversion is accompanied by a visible color change.A similar helix-helix transition of poly((R)-or(S)-(4-((1-(1-naphthyl)ethyl)carbamoyl)phenyl)acetylene)is also briefly described.