Multiple structures in supramolecular solids:: Benzophenone embedded in three different C-methylcalix[4]resorcinarene/bipyridine frameworks

Three different supramolecular frameworks based on C-methylealix[4]resorcinarene (CMCR) and 4,4'-bipyridine are described. All contain benzophenone molecules as guests and are prepared by almost identical hydrothermal procedures, indicating that variations during the cooling process, rather than templating, can lead to different phases. The benzophenone molecules show significantly different conformations, with energies calculated to be 10-17 kJ/Mol higher than that of the isolated benzophenone molecule. CMCR exhibits chair, boat, and crown-like conformations in the three solid phases.