Quadruple Switching of Pleated Foldamers of Tetrathiafulvalene–Bipyridinium Alternating Dynamic Covalent Polymers

Two dynamic covalent polymers P1 and P2 were prepared by alternately linking electron‐rich tetrathiafulvalene (TTF) and electron‐deficient bipyridinium (BIPY 2+ ) through hydrazone bonds. In acetonitrile, the polymers were induced by intramolecular donor–acceptor interactions to form pleated foldamers, which unfolded upon oxidation of the TTF units to the radical cation TTF .+ . Reduction of the BIPY 2+ units to BIPY .+ led to the formation of another kind of pleated secondary structures, which are stabilized by intramolecular dimerization of the BIPY .+ units. The diradical dicationic cyclophane cyclobis(paraquat‐ p ‐phenylene) (CBPQT 2(.+) ) could further force the folded structures to unfold by including the BIPY .+ units of the polymers. Upon oxidation of the BIPY .+ units of the cyclophane and polymers to BIPY 2+ , the first folded state was regenerated. Switching or conversion between the four conformational states was confirmed by UV/Vis spectroscopic experiments.