Lanthanide Template Synthesis of a Molecular Trefoil Knot

We report on a complex featuring three 2,6-pyridinedicarboxamide ligands entwined around a lanthanide (Ln3+) ion. The ligand strands can be cyclized by ring-closing olefin metathesis to form a molecular trefoil knot in 58% yield. Demetalation with tetraethylammonium fluoride quantitatively generates the wholly organic 81-atom-loop trefoil knot.