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O
H
N
N
HN
HN
O
2
[Zn
2
(2)
2
]
N
N
N
N
R
R
(
R
,
S
)-
3
[Ag
2
{(R,S)-3}
2
]
2+
N
N
O
N
N
O
N
N
OH
O
N
N
OH
O
O
5a
4
N
N
O
O
N
N
N
N
5b
[Cu
3
(5b)
2
]
3+
Figure 4.2 First examples for artificial helicates (PM3 minimized structures).
4.2 Structural Dynamics
Usually, helicates are formed in strict self-assembly processes, meaning that the process
leads to the thermodynamic minimum structure. Therefore, reversibility of the individual
binding events between ligand units and metal centres is necessary in order not to be
kinetically trapped before reaching this minimum.
One of the first studies concerning this phenomenon was published by K.N. Raymond's
group [10]. They prepared a series of bis(catechol) ligands that form racemic mixtures of
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