Terminal Is Important for the Helicity of the Self-Assemblies of Dipeptides Derived from Alanine

The organization of peptides and proteins attracts much attention, due to the biofunctionalities of the self-assemblies. Herein, four dipeptides derived from alanine were synthesized. It was found that the handedness of their self assemblies was controlled by the chirality of the alanines at the terminals. The organic self-assemblies were studied using circular dichroism, H-1 NMR, Fourier transform infrared, field-emission electron microscopy, transmission electron microscopy, and X-ray diffraction. The results indicated that the electrostatic interactions among the carboxylate groups and H-bondings among the amide groups at the terminals play important roles in the formation of the organic self-assemblies