The research groups of J. F. Stoddart, Northwestern University, USA, and O. M. Yaghi, University of California, Los Angeles, USA, have reported mechanically interlocked molecules incorporated into a three-dimensional metal–organic framework (MOF).

These collaborators have carried out the synthesis of a donor–acceptor [2]catenane-containing strut, as well as its assembly into a metal–organic framework (see picture for an example). Because of the length of the struts (3.3 nm) there is considerable openness to accommodate the bulky mechanically interlocked molecules in the framework, and therefore are precisely attached with uniform relative orientations throughout the framework.

Figure: Hexagons are formed with six Cu⁺ ions as vertices. A ball-and-stick representation of a hexagonal array of catenanes with six of them inserted into the six edges. Organic struts: gray; crown ethers: red; cyclobis(paraquat-p-phenylene)⁴⁺: blue; Cu: orange.

• A Catenated Strut in a Catenated Metal–Organic Framework
  Q. Li, C.-H. Sue, S. Basu, A. K. Shveyd, W. Zhang,G. Barin, L. Fang, A. A. Sarjeant, J. F. Stoddart, O. M. Yaghi,
  Angew. Chem. Int. Ed. 2010, 49.
  DOI: 10.1002/anie.201003221
• Q. Li, C.-H. Sue, S. Basu, A. K. Shveyd, W. Zhang,G. Barin, L. Fang, A. A. Sarjeant, J. F. Stoddart, O. M. Yaghi,
  Angew. Chem. 2010, 122.
  DOI: 10.1002/ange.201003221