Chemistry Reference
In-Depth Information
a strategy for synthesizing new types of polymers, nanoscience, surface immobili-
zation, and so on [
45
,
63
]. In particular, they have led Scherman and coworkers to
publish their first paper on Q[
n
] chemistry in
Science
in 2012 [
64
].
Compared to the significant achievements in Q[
n
]-based host-guest chemistry,
Q[
n
]-based coordination chemistry or Q[
n
]-based host-guest/coordination chem-
istry was gradually developing in the last several years [
60
]. In fact, the establish-
ment of Q[
n
] chemistry started with Q[
n
]-based coordination chemistry because
the structural characteristics of the first-characterized member of the Q[
n
] family,
Q[6], was based on the determination of the linear coordination polymer of Q[6]
molecules with Ca
2
+
cations [
2
]. ~15 % of studies (among ~1800 papers and pat-
ents before the beginning of October 2014, according to a survey by SciFinder),
are directly related to coordination of Q[
n
]s with metal ions. Moreover, recent
works have revealed that Q[
n
]-based coordination chemistry is gradually chang-
ing from simple coordination to novel Q[
n
]/metal ions complex-based polydimen-
sional coordination polymers or supramolecular assemblies. Such structures could
be useful in applications in the areas of nanotechnology, molecular sieves, sen-
sors, gas absorption and separation, ionic or molecular transport, and heterogene-
ous catalysis [
62
,
65
-
72
]. This topic mainly highlights achievements based on the
direct coordination of Q[
n
]s with metal ions, their complexes, and corresponding
coordination supramolecular assemblies in the areas of Q[
n
]-based coordination
chemistry and Q[
n
]-based host-guest/coordination chemistry.
1.2 General Properties of Outer-Surface Interactions
of Q[
n
]s
Electrostatic potential surface calculations on Q[
n
]s (Fig.
1.4
) indicated that the
regions around the portal carbonyl groups on Q[
n
]s are significantly negatively
charged, the inner surface of the cavities is close to electrostatically neutral,
whereas the outer surface of Q[
n
is is electrostatically positive. It is not surprising
that almost all research in Q[
n
] chemistry has been focused on utilizing the portals
and cavities to construct supramolecular assemblies through the strong charge-
dipole and hydrogen bonding interactions, as well as hydrophobic and hydrophilic
effect derived from the negative portals and rigid cavities of Q[
n
]s. However, few
of them focus on the interaction of outer surface of Q[
n
]s on the Q[
n
]-based coor-
dination polymer and supramolecular assemblies [
61
].
In fact, Chen and coworkers first proposed that the chemical behavior of the
convex outer walls of Q[
n
]s could be explored to develop novel structures and
functional materials when they investigated iodine-assisted supramolecular assem-
blies of helical coordination polymers of Q[
n
] and asymmetric copper(II) com-
plexes [
73
]. Further investigation reveals that the outer surface of Q[
n
] exhibits
much higher affinity to the aromatic moieties of an aromatic organic molecule or
ligand in a complex anion than to the other Q[
n
] units; we call the resulting inter-
actions as outer-surface interaction of Q[
n
]s, such as those involved in C-H
ˀ
,
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