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=CuI or AgI ), which dimerized into an M6 L4 interlocked cage (M=CuI ). Higher (M3 L2 )n oligomers were also selectively obtained: an M12 L8 truncated tetrahedron (M=CuI ) and an M18 L12 truncated trigonal prism (M=AgI ), 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.