N-Terminal Hydrogen Bonding Initiates Morphology Transition from Flat to Twisted Ribbon in an Amphiphilic Dipeptide...

Abundant reversible noncovalent interactions contribute greatly to the anisotropy of supramolecular morphologies and the transformation across multiple structures. However, the trigger (group) to drive the transformation remains obscure. Herein, H-bonding between free N-terminal amines of l-tryptophan derivatives (GTC_n) and DMSO, triggering a morphological transition is revealed from flat to twisted nanoribbons by tuning DMSO/H₂O ratios. Corresponding dynamic macroscopic morphology evolution from an aggregated cluster to a flower-like sphere of gel is observed under an optical microscope. Combined experiments and molecular dynamics (MD) simulations establish this H-bonding as the submolecular trigger, which simultaneously induces the change of π-π stacking, from the J-type to H-type. Alkyl chains at the C-terminus modulate structural dimensions, while gel thixotropy is governed by chiral morphology. These results provide a molecular strategy for precisely triggering twisted ribbon formation in self-assembly alongside the injectable chiral gel systems visible under optical microscopy.