Same knot, longer rope: altering ligand geometry provides control over nuclearity in self-assembled trefoil knots.

Taking advantage of the accumulation of a number of noncovalent intramolecular interactions, octanuclear and hexanuclear trefoil knots are self-assembled based on half-sandwich rhodium fragments. The selective synthesis of either the octanuclear or hexanuclear knot can be controlled by altering different dipyridyl arms.