Chemistry Reference
In-Depth Information
8+
4+
H
N
H
N
N
N
H
N
H
N
Pt
Pt
N
N
H
2
N
N
H
2
H
N
H
N
2
Pt
Pt
N
N
H
2
N
N
H
2
Pt
Pt
H
2
N
N
H
2
4 NO
3
-
8 NO
3
-
60
61
Scheme 22 Equilibrium between monomer ring 60 and catenane 61
O
O
SH
O
O
N
N
HOOC
HS
COOH
N
N
O
O
O
O
63
SH
O
O
H
COOH
N
HOOC
O
O
HS
62
64
Scheme 23 Template dynamic synthesis of [3]catenane
(naphthalenediimides) and 64 with one donor unit (2,6-dimethoxynaphthalene),
were mixed in a high-polarity medium or in the presence of spermine. Then
spontaneous self-assembly and cyclization via disulfide bond formation gave
[3]catenane 62. This example provides an alternative route to the efficient synthesis
of various catenanes.
Doubly interlocked [2]catenanes, Solomon links, are fascinating synthetic
targets because their synthesis is more difficult than that of simple [2]catenanes
(Hopf links) [
129
]. A Solomon link has four crossings, whereas a Hopf link has two
crossings. In 1999, Fujita and Sauvage's group jointly reported formation of a
Solomon link by combination of metal-template and self-assembly strategies
(Scheme
24
)[
130
]. When ligand 66 was treated with Cu(I) and Pt(II) ions, a doubly
interlocking [2]catenane 65 formed quantitatively. Covalently linked Solomon link
69 was readily prepared by mixing diaminobipyridine 67 and diformylpyridine 68
with a 1:1 amount of Zn(II)/Cu(II) (Scheme
25
)[
129
]. The linked structure was
confirmed by X-ray analysis, and each link 70 contains four benzene units and six
pyridine units. A new type of molecular Solomon link was constructed by self-
assembly of three units, two bipyridinium units and one macrocycle, with Pd(II) or
Pt(II) ions [
131
]. It is notable that
interactions, hydrogen bonds, and metal
coordination cooperatively lead to an unusual cyclization mode.
p
p
