Self-Assembly of [3]Catenane and [4]Catenane Based on Neutral Organometallic Scaffolds

The mechanical interlocked structures of [3]catenane were clearly demonstrated by X-ray crystallographic analysis. The single crystals of [3]catenane were grown by slow evaporation of its dichloromethane solution. Mesomeric [3]catenane crystallizes in P-1 space group with two asymmetric [Cu(phen)₂]⁺ units, threading two polyether phenanthroline macrocycles onto the main Pt(II)-O coordinated rhombic metallacycles. The exterior length of [3]catenane is approximately 2.5 nm, resulting in the large cavity with a diameter of approximately 0.8 nm. In addition, the phenyl ring of adjacent molecules exhibited the strong π-π interactions with a centroid-to-centroid distance of 3.86 Å , leading to a liner packing of rhombic motifs and thus generating an interconnected 1D pore channel. Thus, such kinds of catenanes based on organometallic skeletons are expected to be useful in host-guest chemistry.