Pleated polymeric foldamers driven by donor–acceptor interaction and conjugated radical cation dimerization

Two naphthalene (NP) and bipyridinium (BIPY2+) alternately incorporated polymers P1 and P2 have been prepared through the formation of dynamic hydrazone bonds. The polymers formed NP–BIPY2+ donor–acceptor interaction-induced pleated secondary structure. Upon reducing the BIPY2+ units to radical cation BIPY+, intramolecular dimerization of the BIPY+ units induced the backbones to afford another pleated secondary structure. Adding electron-rich macrocyclic polyether bis-1,5-dinaphtho[38]crown-10 or electron-deficient cyclobis(paraquat-p-phenylene) cyclophane did not break the first foldamer by complexing the BIPY2+ or NP units of the polymers, whereas the di(radical cationic) ring of the second cyclophane could break the second foldamer by forming threading complexes with the BIPY+ units of the polymers.

Intramolecular donor–acceptor interaction and conjugated radical cation dimerization have been utilized to drive naphthalene–bipyridinium alternately incorporated polymers to form two different pleated conformations.Figure optionsDownload as PowerPoint slide