'All-in-one' strategy for metalla[3]catenanes, Borromean rings and ring-in-ring complex
Interlocked molecular species have received considerable attention recently, not only because of their intriguing structures and topological importance, but also because of their important applications as molecular machines and nanoscale devices. Benefiting from the reversible coordination bond, some complicated interlocked structure could be realized by high-yield, one-step processes, for example, [2]catenanes and Solomon knot. Molecular Borromean rings (BRs) are [3]catenanes topoisomers in which none of the component rings is linked, but also cannot be separated without breaking one of the rings (Fig. 1). Linear [3]catenanes are another fascinating interlocked three-ring motif. Several effective methods for the construction of organic linear [3]catenanes have been presented. However, the feasible strategies for the synthesis of organometallic linear metalla[3]catenanes based on coordination-driven self-assembly are still very rare. Beyond linear [3]catenanes, ring-in-ring complex are also a very rare structural motif, which can be considered as substructures of BRs and key intermediates for the preparation of...