Abstract:
A simple protocol to create
nanofibers and -rings through a rational
self-assembly approach is described.
Whereas the melamine–oligo(p-phenylenevinylene)
conjugate 1a self-aggregates
to form ill-defined nanostructures,
conjugate 1b, which possesses an
amide group as an additional interactive
site, self-aggregates to form 1D
nanofibers that induce gelation of the
solvent. AFM and XRD studies have
shown that dimerization through the
melamine–melamine hydrogen-bonding
interaction occurs only for 1b. Upon
complexation with 1/3 equivalents of
cyanuric acid (CA), conjugate 1a provides
well-defined, ring-shaped nanostructures
at micromolar concentrations,
which open to form fibrous assemblies
at submillimolar concentrations
and organogels in the millimolar
concentration range. Apparently, the
enhanced aggregation ability of 1a by
CA is a consequence of columnar organization
of the resulting discotic
complex 1a3·CA. In contrast, coaggregation
of 1b with CA does not provide
well-defined nanostructures, probably
due to the interference of complementary
hydrogen-bonding interactions by
the amide group.
