Biology Reference
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Scheme 11.1
Schematic representation of the NMR experiment used to
show the dynamic interconversion between dimer, trimer,
and tetramer.
11.4
Inclusion Complexes
The geometrical characteristics of the central cavity and the electronic
and structural elements of the
-bipydinium-based
metallocycles described earlier make them potentially useful
as receptors in the molecular inclusion processes. This section
describes the self-assembly of inclusion complexes between some of
our metallocyclic receptors with aromatic substrates.
N
-monoalkyl-4,4
11.4.1
Inclusion Complexes with 1:1 Stoichiometry
The
calculated
distance
between
the
bipyridine
moieties
in
metallocycles
is very close to the ideal value for the
inclusion, by means of π-π stacking, of an aromatic guest within the
inner cavity (Fig. 11.3). Therefore, the inclusion of hydroquinone,
1,5-dihydroxynaphthalene, and its derivatives was studied (Fig.
11.4) [21,22]. Alcoxy or hydroxy groups attached to the aromatic
system increase the electron density of
M2
-
M4
the guest, allowing the
establishment of stronger π-donor/π-acceptor interactions with
the bipyridinium moieties. As a consequence of these interactions, a
new intense charge-transfer band appears on the UV
vis spectrum.
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