Concurrent helix extension and chirality enhancement for an artificial helical foldamer complexed with sterically hindered chiral molecules

Constructing and regulating the helical structures of artificial foldamers have been constantly pursued because of their wide applications in chiral recognition, asymmetric catalysis , circularly polarized luminescence , etc. On the one hand, stabilizing the helical structures of foldamers can usually enhance the chirality by decreasing the pitches. On the other hand, the extended helix can be obtained when the π-π stacking interaction in the main chain is weakened. In general, the former aspect is inconsistent with the later. Herein, chiral 1-phenylethylamines, 2-phenylglycinols and leucinols are used as the guests to modulate the folded helix of an artificial poly(phenylenediethynylene)-based foldamer . With the aid of chiral center, the steric hindrance of the chiral guests can increase the distances between the pitches. Meanwhile, a more ordered chain arrangement is induced by such steric effect . As a result, we successfully endow the foldamers with an extended helix and enhanced chirality at the same time.