Evidence of Nanotubular Self-Organization in Solution and Solid States of Heterochiral Cyclo 1:1 [α/α‑Nα‑Bn-hydrazino]mers Series

The cyclization of heterochiral 1:1 [α/α-Nα-Bn-hydrazino]­mers leads to the corresponding cyclotetramer and cyclohexamer 3 and 4. X-ray crystallographic analysis of 3 unveils its ability to self-assemble into nanotubular structures. Further experiments conducted in the solid state through SEM analyses demonstrate the capability of 3 and 4 to form aerogels consisting of a network of nontwisted fibers, thus confirming the presence of self-organization within this series of mixed-hydrazinopeptides. Subsequent FTIR and NMR studies demonstrate the presence of an equilibrium between monomeric (intramolecular H-bonds) and nanotubular (intermolecular H-bonds) forms in solution. This equilibrium can be modified by varying the solvent.