Versatility in self-assembly and morphology of non-coded anthranilic acid and phenylglycine based dipeptide stereoisomers

Beauty in the self-assembly patterns of isomeric dipeptides of Boc-Ant-L-Phg-OMe (1) bearing two rigid, unnatural amino acids (Ant: anthranilic acid, Phg: phenylglycine) is demonstrated. Additionally, self-assembly and morphological variation by the incorporation of a D-amino acid, Boc-Ant-D-Phg-OMe (2), and corresponding reversed sequences of both peptides, Boc-L-Phg-Ant-OMe (3) and Boc-D-Phg-Ant-OMe (4), respectively, are explored. FT-IR study indicated the presence of conformational heterogeneity in the reverse peptides. SC-XRD suggested that 1 and 2 contain helical and beta sheet-like layer architectures, respectively, whereas 3 and 4 exhibited different kinds of helical structures, sheet-like layer architectures, and molecular channels. Optical microscopy, FESEM, FETEM, and AFM images suggested that both C-terminal L- and D-Phg containing peptides (1 and 2) self-assembled to form a vesicular morphology and their reversed sequences, i.e., N-terminal L- and D-Phg containing peptides (3 and 4), displayed a well-organized rod-like fiber structure. TGA analysis revealed that the obtained supramolecular structures have significant thermal stability.

Automated summary

The beauty of self-assembly patterns and morphological variation in isomeric dipeptides has been demonstrated. Different peptide sequences lead to conformational heterogeneity and various molecular structures, which are important for the thermal stability of the materials.