Self-Complementary Dimers Based on Zwitterionic Halogen Bond Donors

Even though halogen bonding is routinely used in crystal engineering and beyond, motifs offering multipoint interactions are still rare. This applies in particular to self-complementary systems which incorporate both halogen bond donating and accepting moieties. In this study, we present the first isolated homodimers based on a zwitterionic halogen bond donor, in which an iodolium core acts as Lewis acidic unit and a sulfonate group acts as Lewis base. Initial experiments with a carboxylate variant featured too strong coordination, leading to poor solubility. The optimized sulfonate systems, in contrast, resulted in strongly bound dimers with halogen bond distances of up to 2.73 Å. We anticipate this motif to form the basis for the further development of halogen-bonding-based linkers.