Argentivorous Molecules: Structural Evidence for Ag⁺–π Interactions in Solution

Tetra-armed cyclens bearing aromatic side arms were prepared by the reductive amination of cyclen with substituted benzaldehydes. When equimolar amounts of Ag+ ions were added to the ligands, the aromatic rings covered the Ag+ ions incorporated in the ligand cavities, as if the aromatic ring “petals” caught the Ag+ ions in the way an insectivorous plant (Venus flytrap) catches insects. The ligands are called “argentivorous molecules”. Evidence of intramolecular Ag+–π interactions in solution and in the solid state is reported.