Microtubes with Rectangular Cross-Section by Self-Assembly of a Short β‑Peptide Foldamer

In nature, complex and well-defined structures are constructed
by the self-assembly of biomolecules. It has been shown that β-peptide
foldamers can mimic natural peptides and self-assemble into three-dimensional
molecular architectures thanks to their rigid and predictable helical
conformation in solution. Using shorter foldamers, which can be prepared
more easily than longer ones, to form such architectures is highly
desirable, but shorter foldamers have been overlooked due to the seemingly
inferior number of intramolecular hydrogen bonds to stabilize a folded
state in solution. Here we report that a β-peptide tetramer,
although it lacks full helical propensity in solution, does self-assemble
to form well-defined microtubes with rectangular cross-section by
evaporation-induced self-assembly.