1.D.172. The Acyclic αγα-Tripeptide with Fluorinated-Furanoid Sugar Framework (ATFFF) Family
Acyclic αγα-tripeptides derived from fluorinated-furanoid sugar amino acid frameworks act as reverse-turn inducers with a U-shaped conformation, whereas the corresponding nonfluorinated αγα-tripeptides show random peptide conformations (Roy et al. 2015). NMR studies showed the presence of bifurcated weak intramolecular hydrogen bonding (F···HN) and N+···Fδ- charge-dipole attraction compel the amide carbonyl groups to orient antiperiplanar to the C-F bond, thus, demonstrating the role of the fluorine substituent in stabilizing the U-shaped conformation. U-shaped tripeptide self-assembly is stabilized by the intermolecular hydrogen bonding between C═O···HN with antiparallel orientation. The morphological analysis by FE-SEM, on solid samples, showed arrangement of fibers into nanorods. The antiparallel self-assembled pore of the fluorinated tripeptides illustrates the selective ion-transport activity (Roy et al. 2015). These systems were reviewed by Malla et al. 2021.