QM calculations of TbPTR1-ligand interaction energy. To evaluate the halogen interactions in a systematic, non-empirical manner, the inhibitor was truncated to the substituted benzene (Fig. in SI). Together with compound I (mClpCl), shown in Fig. , 18 ligand fragments were analyzed. The meta-and para-substitutions (also referred to as 'm' and 'p', respectively) with a halogen series (Cl, F, Br, CF 3 ), methyls, and unsubstituted variants, were considered. The compound variant naming is shown in Fig. ; e.g., the fragment with both para and meta positions of phenyl is named mClpCl, while the fragment with a substitution only at the meta position is named mCl.