Formation and Modulation of Nanotubular Assemblies of Oligourea Foldamers in Aqueous Conditions using Alcohol Additives.

There is considerable interest in the rational design of controllable, bioinspired supramolecular systems as a potential means to create new biocompatible and functional materials able to mimic and build upon the characteristics of natural biopolymers. Here, the alcohol-controlled aqueous self-assembly of an amphiphilic helical oligourea foldamer (artificial folded oligomer) into a diverse array of tubular fibril architectures is reported. Electron microscopy studies provide details of the morphological evolution of the foldamer nanostructures from protofibrils to fibers, with high resolution X-ray crystal structures providing an atomic-scale view of these assemblies, and solution studies indicating the assembly and morphology to be affected by alcohol polarity and concentration. Overall, the results reported here highlight oligourea foldamers as suitable building blocks for the formation of a diverse range of tubular morphologies in a controllable manner.