Figure 1

Schematic representation of NDI-L-Glu (1) aggregation pathways, showing the stacking of dimers bound using two hydrogen bonds at (A) acidic pH resulting in left-handed helix, (B) the self-assembly of 1 in the range of physiological pH which is initiated by both left- and right-handed oligomers due to the equilibrium between these two conformations at the molecular level, resulting in both left- and right-handed twisted superstructures, and (C) alkaline pH which resulted in right-handed helical superstructures. This morphology dependency of these self-assemblies on pH shows the importance of the hydrogen bonding between two molecules of 1 among other interactions in the self-assembly process. The conformation of 1 changes dihedral angular twist direction resulting in opposite direction helical superstructures.