Chemistry Reference
In-Depth Information
Figure 4.4
Finite and infi nite supramolecules can be achieved by combination of ditopic
linear and angular building blocks, or by combining different linear building blocks
4.1.2 Metal ions and Complexes as Building Blocks
Coordination of transition metal ions or complex fragments to nucleobases permits
the assembly of either discrete geometric entities or polymeric structures. The selec-
tion of metal ions, or complex fragments, is based on several factors. Most important
is the ability to display the appropriate coordination geometry for the desired archi-
tecture of the fi nal supramolecule. These geometries may be considered broadly as
either linear or angular, as exemplifi ed by the use of
cis
- and
trans
- amine complexes
of platinum, with angular (90°) and linear (180°) geometries. Figure 4.4 gives a
summary of infi nite architectures of coordination supramolecules obtained by com-
bination of linear and angular subunits.
4.2 Discrete Architectures
Many metal fragments offer a variety of specifi c angles for construction as a conse-
quence of their known coordination geometries. However, metal fragments with
bond angles at 90 or 180 ° are the most used with nucleobases, to form discrete, or
closed, structures.
Formation of fi nite architectures require the self-assembly of either angular or
a combination of angular and linear building blocks. Figure 4.5 provides a summary
of discrete supramolecules that have been formed using nucleobases and metal ions
as building blocks.
