Alignment of twisted nanoribbons formed by C17H35CO-Val-Ala sodium salts.

ABSTRACT

C17H35CO-l-Val-l-Ala and C17H35CO-d-Val-d-Ala sodium salts can form physical gels in water, and self-assemble into right- and left-handed twisted nanoribbons, respectively. FT-IR and 1H NMR spectra indicate that the H-bonding between the neighboring valine residues and electrostatic interactions of carboxylate groups play important roles in the formation of helical nanoribbons. Circular dichroism characterization and theoretical chemical calculations indicate that the dipeptide segments pack in a helical manner. X-ray diffraction patterns and theoretical chemical simulations indicate an interdigitated bilayer structure. The hydrogels exhibit a thixotropic behavior. The twisted nanoribbons are able to align under directional force.