Self-Assembly of Coordination Polyhedra with Highly Entangled Faces Induced by Metal-Acetylene Interactions

The self-assembly of nanostructures is dominated by a limited number of strong coordination elements. Herein, we show that metal-acetylene π-coordination of a tripodal ligand (L) with acetylene spacers gave an M₃ L₂ double-propeller motif (M=Cu^I or Ag^I ), which dimerized into an M₆ L₄ interlocked cage (M=Cu^I ). Higher (M₃ L₂ )_n oligomers were also selectively obtained: an M₁₂ L₈ truncated tetrahedron (M=Cu^I ) and an M₁₈ L₁₂ truncated trigonal prism (M=Ag^I ), both of which contain the same double-propeller motif. The higher oligomers exhibit multiply entangled facial structures that are classified as a trefoil knot and a Solomon link. The inner cavities of the structures encapsulate counteranions, revealing a potential new strategy towards the synthesis of functional hollow structures that is powered by molecular entanglements.