reestablish an equilibrium between the complexed and uncomplexed states in solution.
Therefore, Fig. 3b could be seen as a “thermal switch” though the response was very
slow. Taking advantage of the multivalency of TTF, Becher et al. [14] also synthesized a
cyclophane containing TTF as electron-rich macrocycle and linked the pyromellitic
diimide as electron acceptor to the cyclophane, thus resulting with the corresponding
pseudo[1]rotaxane (Fig. 3c). And the mechanical behavior of it was systematically
studied.
In 2006, Cooke et al. [15] reported a self-complexed donor-acceptor pseudo[1]
rotaxane system using CBPQT
4+ as acceptor and wheel part, and the electron-rich
pyrrole unit connected with CBPQT
4+ as the axle part (Fig. 4). This pseudo[1]
rotaxane system possessed excellent photoelectric property. The self-complexed
conformation of this pseudo[1]rotaxane could be disrupted thermally,
Fig. 2 (a) Pseudo[1]rotaxanes based on CBPQT
4+ [9, 10]; (b) conformation transformation of
CBPQT
4+ -viologen-based pseudo[1]rotaxane upon the addition of Zn dust [12]
Fig. 3 Pseudo[1]rotaxanes based on CBPQT
4+ and TTF with (a) rigid or (b) flexible linkage;
(c) pseudo[1]rotaxane based on cyclophane containing TTF as host and pyromellitic diimide as
guest [14]
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