ultrasounds, which constitutes a reversible process ( 271 ).
Figure 20 shows our findings based on the use of substituted
terpyridine ligands which are able to gelate in water even in
the presence of metal ions which can coordinate the tridentate
ligand. Emission can be observed from the gel depending on the
nature of the metal ions.
As supramolecular gels provide fibrous aggregates with long-
range order, they are heavily used in biology and medicine as
extracellular matrix, drug delivery, and cosmetics, but they could
be also of interest in the fields of optoelectronic devices and
sensors. In this context, organometallic gelators can display
multiple functionalities and properties which combine ligands
or organic fragments and metal ions which further can lead to
metal–metal interactions influencing their properties( 272 ).
NOH–2HBrGelON NFIG. 20. Stable hydrogel is formed with terpyridine-type systems
upon application of ultrasound to the water solution. Left: picture of
the gel; right: SEM image of the gel and cartoon representation of pos-
sible stacking of the molecules to form 3D networks. The nature of the
gels can be modulated by the addition of metal ions. Reproduced with
the permission of the Royal Society of Chemistry ( 271 ).
82 CRISTIAN A. STRASSERTet al.