Self-complementary Dimers Based on Zwitterionic Halogen Bond Donors

Even though halogen bonding is routinely used in crystal engineering and beyond, multipoint interactions are still quite rare. This applies in particular to self-complementary systems which incorporate both halogen bond donating and accepting moieties. Herein, we present the first homodimer based on a zwitterionic halogen bond donor in which a iodolium core acts as Lewis acidic unit and a sulfonate groups acts as Lewis base. Prior experiments with a carboxylate variant had indicated that it featured too strong coordination, leading to poor solubility. The sulfonate system, in contrast, resulted in a strongly bound dimer with halogen bond distances of 2.73 Å. We anticipate that this motif will form the basis for the further development of halogen-bonding-based linkers.