Supramolecular Chemistry
Ligand Design
New supramolecular assemblies of metals are currently of interest
for their potential uses in a large variety of different applications.
These range from electronic, photonic, and mechanical devices of importance
to nanotechnology to the control of redox activity, magnetic and luminescence
properties as well as anion recognition and electrochemical sensing.
Here is an example of a derivative of a new class of Schiff base ligands
which has been specifically designed with functional acetylenic groups
(-C≡C-R) in order to provide sites for additional reactivity and/or binding
or complexation. This trinuclear zinc(II) derivative contains eight
Co and three Zn atoms.
Group 13 Elements
Noncovalent attractive forces such as hydrogen bonding and
π-π interactions are now recognized as key features in the self-assembly
of multicomponent molecular architectures. For the Group 13 elements,
large supramolecular assemblies involving dative covalent interactions
between Lewis acid centers and nitrogen or oxygen donor bases or halogens
are well known.
Here is something different - two examples of Group 13 organometallics
which exhibit novel supramolecular structures, namely [AlMe(C6F5)(µ-Me)]2
(top picture) and GaMe(C6F5)2 (bottom picture).
In the top picture, intermolecular π-π stacking between pairs of offset C6F5
rings creates an unusual zig-zag one-dimensional chain. In the bottom picture, a
linear chain-like supramolecular assembly is formed via intermolecular aryl-F→Ga
interactions. These compounds raise some interesting possibilities
for the preparation of novel materials.