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R
2
R
2
R
1
O
OR
1
OR
2
R
2
O
N
N
R
2
R
2
N
R
1
O
OR
1
R
1
O
OR
1
OR
2
R
2
R
2
R
1
= dodecyl
R
2
= octyl
29
30
31
Scheme 11 Macrocycles with 9,10-anthracene units
compound having an enclosed cavity within the network often includes one or more
guest species (molecules, ions, etc.). Weak interactions between aromatic walls and
guest species as well as host-guest compatibility in size and shape play important
roles in forming inclusion complexes.
5.1 Cage Networks with Covalent Linkers
Compound 32, called spheriphane, was synthesized by macrocyclization of a 1,3,5-
tris(2-phenylethyl)benzene precursor by V¨gtle et al. (Scheme
12
)
71
].
This compound has a spherical framework, where four benzene units are clamped
by six ethylene linkers. The radius of the intramolecular cavity is 0.28
˚
, and this
space is sufficient for the inclusion of small metal ions. Several spheriphane analogs
have been studies as ion receptors and fullerene related compounds. Compounds 33
and 34 are larger spheriphane derivatives with an extra three benzene units [
72
,
73
].
Compound 34 extracted Ag
+
ion from an aqueous solution much more efficiently
than 32 and 33. This remarkable selectivity of 34 was applied to the incorporation in
ion-selective electrodes for Ag
+
and Tl
+
ions. In annelated spheriphane 35, three
ethylene linkers are annelated by benzo groups [
74
]. The fully annelated derivative
with ten benzene rings (C
60
H
36
) should be a potential precursor to C
60
. Compound
36 can be regarded as spheriphane with three-atom linkers involving heteroatoms
[
75
]. This compound recognized NH
4
+
and K
+
ions under the conditions of positive
ESI mass spectroscopy.
Cage-type compounds based on a 1,3,5-tribenzylbenzene subunit were reported
by Kim et al. (Scheme
13
)[
76
]. Compounds 37 and 38 have prismatic frameworks
with two cap benzene units and three wall benzene units connected by -CH
2
- and
-O-CH
2
- linkers. ESI-mass measurements revealed that these compounds formed
a 1:1 complex with various metal ions and NH
4
+
. In the presence of Li
+
,Na
+
,K
+
,
and NH
4
+
, 37 with
m
-phenylene walls binds Li
+
selectively, while 38 with
p
-phenylene wall units binds both Li
+
and NH
4
+
. Prismatic cage compound 39 was
constructed from enantiopure cap benzene units and three wall benzene units via
