Well-Defined Porphyrin Architectures From Self-Assembly and Dewetting - Molecular Self-Assembly: Advances and Applications - page 255

way. It is therefore proposed that the alignment is caused by dipole-
dipole interactions between the molecules of 5CB and the huge
dipoles present along the columnar stacks of porphyrins, caused by
the extensive alignment of the amide functions in the cores.

Figure 8.12 Application of the linear patterns of as an alignment layer

for liquid crystalline molecules. (A) Structure of the liquid
crystalline compound 5CB (top), a schematic of the porphyrin
stacks of

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(bottom), and an indication of the direction of the
dipole in both the liquid crystal molecule and the stack.

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8.3 Conclusion and Outlook

It has been demonstrated that by combining molecular self-assembly
with the dewetting of a solution on a surface, a variety of well-
defined porphyrin assemblies can be obtained over multiple length
scales, spanning from single molecule to macroscopic dimensions.
Using a very simple procedure, namely the evaporation of dilute
solutions of porphyrin derivatives on a surface, micrometre-sized
ring-shaped assemblies as well as linear assemblies with lengths up
to a millimetre can be obtained. Despite its apparent simplicity, the
underlying factors that govern the process are a complex interplay
of the rather predictable supramolecular interactions between
the self-assembling molecules, and the less understood physics of
dewetting. For this reason it remains a challenge to predict a priori

the outcome of a self-assembly/dewetting process on a surface, and
systematic studies will be needed to get a complete understanding
of the underlying principles governing the thermodynamics and
kinetics of a particular system.
As far as applications are concerned, so far only the linear
porphyrin patterns have proven to be successful as alignment layers