Chemistry Reference
In-Depth Information
Chapter 1
Cucurbit[
n
]uril Chemistry
Abstract
Because of their superior molecular recognition properties in aqueous
media, cucurbit[
n
]urils (Q[
n
]s or CB[
n
]s), which bear a rigid hydrophobic cavity
and two identical carbonyl fringed portals, have attracted much attention in supra-
molecular chemistry. Till date, the homologs of unfunctionalized cucurbit[
n
]urils
include 5, 6, 7, 8, 10, and 14. Meanwhile, a number of substituted cucurbit[
n
]urils
(SQ[
n
]s) and their derivates were reported during the last decade. Therefore, in
this chapter the development of cucurbit[
n
]urils and their derivates is first briefly
reviewed. Importantly, the general properties of out surface-interactions of Q[
n
]s
proposed by us recently and their roles in Q[
n
]-based coordination chemistry or
Q[
n
]-based host-guest/coordination chemistry are also highlighted in this chapter.
Keywords
Substituted cucurbit[
n
]urils
·
Homologs
·
Outer-surface interactions
·
Supramolecular assemblies
·
Host-guest chemistry
·
Coordination chemistry
1.1 Development of Cucurbit[
n
]urils and Their Derivates
Cucurbit[
n
]urils (commonly abbreviated as Q[
n
]s or CB[
n
]s) are among the mac-
rocyclic receptors known to date besides, crown ethers, cryptands, cyclodextrins,
and calixarenes. As the first reported family member, cucurbit[6]uril (Q[6]) was
originally synthesized in 1905 by Behrend and coworkers from the condensation
of glycoluril and formaldehyde under strongly acidic conditions [
1
]. However, it
was not until 1981 that Mock structurally characterized Q[6] as a structure com-
prising six pumpkin-shaped glycoluril units linked with 12 methylene bridges
(Fig.
1.1
) [
2
]. Later, the supramolecular chemistry of Q[6] continued to develop
in the 1980s and 1990s as a result of the pioneering work by Mock, Buschmann,
Kim, and their coworkers [
3
-
6
].
In 2000, the research groups of Kim and Day performed the successful isola-
tion and X-ray characterization of Q[5], Q[7], and Q[8] (Fig.
1.2
) [
7
-
9
].
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