Quadruple Switching of Pleated Foldamers of Tetrathiafulvalene–Bipyridinium Alternating Dynamic Covalent Polymers |
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| Authors: | Lan Chen Dr Hui Wang Prof Dr Dan‐Wei Zhang Prof Dr Yaming Zhou Prof Dr Zhan‐Ting Li |
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| Affiliation: | Department of Chemistry, Collaborative Innovation Center of Chemistry for Energy Materials (iChEM), Fudan University, 220 Handan Road, Shanghai 200433 (China) |
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| Abstract: | Two dynamic covalent polymers P1 and P2 were prepared by alternately linking electron‐rich tetrathiafulvalene (TTF) and electron‐deficient bipyridinium (BIPY2+) 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 BIPY2+ 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) (CBPQT2(.+)) 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 BIPY2+, the first folded state was regenerated. Switching or conversion between the four conformational states was confirmed by UV/Vis spectroscopic experiments. |
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| Keywords: | dynamic covalent polymers donor– acceptor interactions foldamers radical cations viologens |
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