In helical polymers, helical sense induction is usually commanded by teleinduction mechanism, where the largest substituent of the chiral residue directly attached to the main chain is the one that commands the helical sense. In this work, different helical structures with different helical senses are induced in a helical polymer [poly‐(phenylacetylene)] when the conformational composition of two different dihedral angles of a pendant group with more than two chiral residues is tamed. Thus, while the dihedral angle at chiral residue 1 [(R)‐ or (S)‐alanine], attached to the backbone, produces an extended or bent conformation in the pendant resulting in two scaffolds with different stretching degree, the second dihedral angle at chiral residue 2 [(R)‐ or (S)‐methoxyphenylacetamide] places the substituents of this chiral center in a different spatial orientation, originating opposite helical senses at the polymer that are induced through a total control of the “chiral overpass effect”.
In helical polymers, helical sense induction is usually commanded by teleinduction mechanism, where the largest substituent of the chiral residue directly attached to the main chain is the one that commands the helical sense. In this work, different helical structures with different helical senses are induced in a helical polymer [poly-(phenylacetylene)] when the conformational composition of two different dihedral angles of a pendant group with more than two chiral residues is tamed. Thus, while the dihedral angle at chiral residue 1 [(R)-or (S)-alanine], attached to the backbone, produces an extended or bent conformation in the pendant resulting in two scaffolds with different stretching degree, the second dihedral angle at chiral residue 2 [(R)-or (S)-methoxyphenylacetamide] places the substituents of this chiral center in a different spatial orientation, originating opposite helical senses at the polymer that are induced through a total control of the "chiral overpass effect".
The design, synthesis and structure elucidation of helical polymers with a predominant helical sense have been actively studied during the last years due to the different applications that these materials can present. The helical sense of a polymer can be determined by the chirality of the pendants and is directly related to the distance from the chiral centre to the backbone. In order to achieve the best folding, the distance between the polymeric backbone and the chiral centre should be small, so the closer is the pendant to the backbone the better is the helical control. Nevertheless, few examples have demonstrated that the helical control is also possible when a spacer is placed between the pendant and the backbone. Related to this, our research group has proven that it is possible to have chiral teleinduction when the chiral centre is separated from the backbone through a flexible spacer. Recently, we have also demonstrated that the transmission of information is also possible when a long rigid and achiral spacer is employed observing that, although the chiral centre is placed in a remote position, its chirality is transmitted to the polyene backbone through a previous organization in a helical fashion of the rigid spacer. Herein we describe another family of polymers bearing an achiral rigid spacer between the pendant and the backbone, evaluating the effect that the aromatic substitution pattern of the rigid spacer has in the final folding of the polymer.
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