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Fig. 3.8
First row
the structures of the five related SQ[5]s (top view).
Second row
the corre-
sponding trigonal-planar branches constructed from SQ[5]s and K
+
ions.
Third row
2D networks
based on coordination of alkyl-substituted Q[5]s and potassium cations.
Fourth row
the six-mem-
bered “bracelets” isolated from the corresponding networks
knots [
21
-
24
]. Apart from being esthetically attractive, theses molecules offer the
potential for nanoscale applications in molecular devices and new materials [
22
].
Pioneering work by Kim and coworkers was undertaken utilizing long-chain guests
ending with active moieties. They accomplished this by first threading Q[6] to form
rotaxanes through the coordination of transition metal ions, and then using cat-
enanes, and molecular necklaces. These achievements have been reviewed by Kim
and others [
25
]. This field has since been extended to include Q[8]. The intrinsic
ability of Q[8] to encapsulate two guest molecules, i.e., a pair of electron-rich and
electron-deficient guest molecules, has been utilized to form a “molecular neck-
lace” through host-stabilized intermolecular CT complexes (Scheme
3.2
) [
26
].
These novel architectures prompted us to exploit the strategy of changing the Q[
n
]-
based 1D polymer to polydimensional architectures through the direct coordina-
tion of Q[
n
]s with metal ions. The coordination between two adjacent portals and
metal ions was anticipated to lead to the formation of a string of Q[5]s. In addition,
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