W0151

The Role of Host-Guest Interactions in Determining the Structure of Simple Calixarene Inclusion Compounds. G. D. Enright, K. A. Udachin, J. A. Ripmeester, National Research Council, Ottawa, Canada.

Calixarenes have been shown to be versatile materials that can serve as hosts for a wide variety of guest molecules. In particular, t-butylcalix[4]arene, one of the simplest calixarenes, has been shown to have a number of guest-directed structural motifs. By far the most common are the 1:1 (P4/n) and 2:1 (P4/nnc) tetragonal crystal forms. In the present study we examine the structural variety that is encountered as various fluorinated benzene guests are included in the t-butylcalix[4]arene host. In addition to the commonly observed 1:1 tetragonal bilayer structure (P4/n) a couple of monoclinic distortions of this motif are observed where the guest alignment in adjacent host molecules are correlated. In addition two unexpected structural arrangements were observed. With one isomer of tetrafluorobenzene, the guest molecules are intercalated between layers of self-included host dimers and with hexaflurobenzene a 1:2 host guest material forms with a π-stacked three-dimensional framework where columns of self-included host dimers are connected together by guest molecules.