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Quadruple Switching of Pleated Foldamers of Tetrathiafulvalene–Bipyridinium Alternating Dynamic Covalent Polymers
Author(s) -
Chen Lan,
Wang Hui,
Zhang DanWei,
Zhou Yaming,
Li ZhanTing
Publication year - 2015
Publication title -
angewandte chemie international edition
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 5.831
H-Index - 550
eISSN - 1521-3773
pISSN - 1433-7851
DOI - 10.1002/anie.201410757
Subject(s) - tetrathiafulvalene , chemistry , intramolecular force , cyclophane , viologen , covalent bond , diradical , polymer , polymer chemistry , crystallography , electron acceptor , photochemistry , acetonitrile , tetracyanoquinodimethane , stereochemistry , crystal structure , molecule , organic chemistry , singlet state , physics , nuclear physics , excited state
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.