Template‐Free Self‐Assembly of Molecular Trefoil Knots and Double Trefoil Knots Featuring Cp*Rh Building Blocks

Understanding and controlling the topology of self-assembled structures plays a fundamental role in supramolecular chemistry. Herein we describe the preparation of a series of tetranuclear metallarectangles and hexanuclear trefoil knots featuring Cp*Rh building blocks by the template-free self-assembly of four different rigid and flexible ligands. Transformations between the trefoil knots and the corresponding macrocycles can be induced using concentration effects. Remarkably, the hexanuclear trefoil knot 5 was shown to assemble further, providing rare examples of [12+1] heteronuclear double trefoil knots ( 5a/5b/5c/5d ) via coordination of the amide oxygen atoms to the secondary metal ions Na+/K+/Ca2+/Cd2+. The synthetic results are supported by single-crystal X-ray diffraction analysis.