Design and Exploration of Tubular Assemblies of Hybrid Cyclic Peptides

Self-assembling cyclic peptides are important building blocks to construct synthetic nanotubes.They can be primarily classified into cyclic -alt(D,L)-peptides, cyclic -peptides, cyclic ,-peptides, and cyclic peptides incorporating or -amino acids based on their composition. 1Our research focuses on design of novel cyclic peptides derived from (O)- 5 -amino acid residues, consisting of a hybrid structure of crown ether and peptide macrocycles.These peptides exhibit unique self-assembly, forming hollow sub-nanotubular structures with unidirectional hydrogen bonds.These cyclic dipeptides, adopting non-centrosymmetric space groups, display significant anisotropy, suggesting potential macroscopic dipole extensions. 2 Furthermore, their inherent macrodipole orientation inspires investigation into their piezoelectric properties, opening new avenues for diverse applications.Additionally, we have synthesized size-variant macrocycles featuring (O)- 5 amino acid residues which also fold into self-assembled nanotubes in solution and gas phase.This apparent supramolecular size-variant nanotube acts as an anion-selective transporter.The ion channel activity and selective transport of these structures are examples of the great potential that cyclic peptide nanotubes show for the construction of functional artificial transmembrane transporters.