Anion-Induced Self-Assembly of Bis(cyclopeptides) with Rigid Linkers

The presence of sulfate anions induces the self-assembly of anion-binding bis(cyclopeptides) in which two cyclopeptide rings are connected via a rigid linker. In this way, 2:2 complexes are formed in which two anions are sandwiched between two bis(cyclopeptide) moieties. Mixed species can be formed if two bis(cyclopeptides) containing different linkers are present and the structural mismatch between the linkers can be compensated for in the self-assembled product. Sulfate complexation seems to proceed with positive cooperativity, leading primarily to the fully formed complexes. As a consequence, these bis(cyclopeptides) represent useful building blocks for the anion-mediated formation of self-assembled products with controllable structural complexity.