Selective construction and stability studies of a molecular trefoil knot and Solomon link.

Two novel compounds, a molecular trefoil knot and a Solomon link, were constructed successfully through the cooperation of multiple π-π stacking interactions. A reversible transformation between the trefoil knot and corresponding [2+2] macrocycle could be achieved by solvent- and guest-induced effects. However, the Solomon link maintains its stability in different concentrations, solvents and guest molecules. Single-crystal X-ray crystallographic data, NMR spectroscopic experiments and ESI-MS support the synthesis and structural assignments. These synthesis methods open an inroad into the further development of smart materials, which will push the advance of rational design of biomaterials.