A NOVEL SUPRAMOLECULAR ASSEMBLY: SWITCHABLE ENCAPSULATION OF A GUEST MOLECULE BETWEEN TWO BOWL-SHAPED MOLECULE. Gunnar Olovsson, Robert G. Chapman, John C. Sherman and James Trotter, Department of Chemistry, 2036 Main Mall, University of British Columbia, Vancouver, British Columbia, Canada, V6T 1Z1

The highly stable self-assembled complex 1(pyrazine is formed via charged hydrogen bonds between the bowls, and van der Waals and electrostatic interactions between the bowls and the pyrazine guest molecule. The reaction is reversible (by adjusting the pH) and strongly guest-selective^1,2. Larger assemblies are being developed with potential of nanotechnological applications, like for example drug delivery devices etc. Crystal structure: Tetragonal P4cc, a=b=22.661(3), c=30.209(2), V=15513(3)³. The pyrazine guest molecule sits on the 4-fold axis and is thus disordered. Each of the two crystallographically independent complexes of 1(pyrazine is surrounded by 4 molecules of the counterion DBU ([C₉H₁₇N₂]⁺). Nitrobenzene solvent and water are also present in the crystal.

(1) Chapman, R.G. and Sherman, J.C. (1995) J. Am. Chem. Soc. 117, 9081-9082.

(2) Grotzfeld, R.M., Branda, N. and Rebek, J. Jr. (1996) Science, 271, 487-489.

1Guest