The Topological Transformation of 4₁ Knot to 4₁² Link through Supramolecular Fusion

Realizing topological transformation through supramolecular fusion is particularly challenging, as the self-assembly of disparate components often results in the orthogonal assembly of building blocks into distinct structures rather than the formation of a heteroleptic architecture. This study introduces a topological transformation, transitioning from a figure-eight knot (4₁ knot) to a Solomon link (4₁² link) through a supramolecular fusion process. By employing two structurally similar amino acid ligands (<b>L1</b> and <b>L3</b>) of varying lengths as bridge ligands, we obtained figure-eight knot <b>1</b> and a molecular tweezer-like compound <b>3</b> when individually complexed with binuclear Cp*Rh acceptor <b>B1</b>. Our results revealed that subtle modifications to bridge ligands can lead to dramatic changes in their structures and recognition properties. Moreover, we successfully achieved the targeted formation of a heteroleptic Solomon link <b>4</b> by blending figure-eight knot <b>1</b> and compound <b>3</b> in a 1:1 ratio without the need for templates. This procedure effortlessly converted the 4₁ knot into a 4₁² link, thus marking a significant advancement in the topological transformation. This work not only marks the construction of the first heteroleptic Solomon link comprising two distinct metallamacrocycles but also demonstrates a process of supramolecular fusion-based topological transformation involving three distinct topological structures.