Chirality-driven molecular packing structure difference and potential application for 3D printing of a series of bola-type Ala–Phe dipeptides†
A series of bola-type dipeptides based on an Ala–Phe building block was synthesized by altering the chirality of Ala and Phe. They were able to self-assemble into right- or left-handed helical nanofibers in a mixture of methanol and water. Both the handedness of the nanofibers and that of the molecular stacking were controlled by the chirality of the phenylalanine residue. 1H NMR, circular dichroism and FT-IR characterizations indicated that the formation of the nanofibers was driven by the hydrophobic association of the hydrocarbon chains, π–π stackings of the phenyl rings and hydrogen bonds. X-ray diffraction patterns showed that the diastereoisomers packed into different structures. These bola-type Ala–Phe dipeptides can be potentially used for 3D printing.