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through the use of dynamic covalent chemistry (DCC) [
192
]. DCC employs
dynamic, reversible (self-correcting) covalent bonds to allow a chemical reaction
to reach its energetic minimum. In the synthesis of MIMs, thiol-disulfide exchange
[
193
-
195
], olefin metathesis [
196
-
200
], imine bonds [
76
,
201
-
204
], and even
dynamic S
N
2 reactions [
205
-
207
] have been used to put template-directed reactions
into a thermodynamic regime. Likewise, the Fujita group has pioneered the use of
labile coordinative bonds to achieve thermodynamic control in MIM synthesis
[
208
]. Fig.
27
highlights some of these beautiful thermodynamically driven, near-
quantitative MIM syntheses. Elegant, one-step quantitative syntheses of simple
MIMs are now becoming fairly routine, though we should note that kinetically
controlled MIM reactions are also sometimes very high-yielding as well [
209
].
The Borromean Rings (Fig.
4
) are among the most elegant of relevant examples;
this previously elusive topology, which had been sought after in a stepwise fashion
for over a decade [
210
], was finally achieved [
156
] in one step by employing the use
of reversible imine bonds among six
exo
bidentate diaminobipyridine (DAB)
ligands and six
endo
diformylpyridine (DFP) ligands, in combination with the
templating effect of six zinc ions (Scheme
1
).
NH
2
O
6 Zn
2+
+
6
6
N
N
O
O
DFP
N
O
NH
2
DAB
BR
-
Zn
12+
Scheme 1 The elegant 18-component self-assembly of molecular Borromean rings under ther-
modynamic control [
156
], which utilizes reversible imine bonds to incite self-correction of the
iconic interlocked structure at equilibrium
4.3.4 Post-Synthesis Modification
An elegant solution to building new mechanically interlocked architectures has
been to make them amenable to further modification after their synthesis. This
category is particularly broad, as it encompasses all manner of reactions that have
been performed on MIMs, including their organization in scaffolds (e.g., MOFs,
see Fig.
15
, Sect.
3.3
) and interfaces, polymerization [
211
,
212
], and other
