Thierry Brigaud

Oligomers of the achiral α ‐aminoisobutyric acid (Aib) adopt a 3 10 helical conformation in which the screw‐sense preference can be controlled by a single chiral residue. The use of the fluorinated residue α ‐Trifluoromethylalanine ( α ‐TfmAla) revealed a unique way to both induce and measure the screw‐sense preference of such oligomers acting as 19 F NMR probe. This work proposes a systematic study of the effect of this fluorinated chiral inducer on the helical screw‐sense preference of poly‐Aib oligomers. The impact of the position of the fluorinated residue into pentamers ( N ‐terminal, central or C ‐terminal) as well as the nature of the C ‐terminal capping of the peptides was thoroughly studied in light of complete structural analysis. A deeper understanding of the fluorine effect was achieved confirming the unique ability of α ‐TfmAla as a helical screw‐sense controller.