H-Phe(3,5-DiF)-OH is a difluorophenylalanines in the L-configuration [L-(F2)Phe]. H-Phe(3,5-DiF)-OH can be incorporated into the thrombin receptor-tethered ligand peptide SFLLRNP to identify the phenyl hydrogens of the Phe-2 residue involved in the CH/π receptor interaction.