Cavities, layers, and channels in the hosting framework of molecular complexes derived from cephradine
Kemperman GJ, de Gelder R, Dommerholt FJ, Raemakers-Franken PC, Klunder AJH, Zwanenburg B
EUROPEAN JOURNAL OF ORGANIC CHEMISTRY (19): 3641-3650 OCT 2001

Abstract:
The cephalosporin-type antibiotics Cephradine, Cephalexin, and Cefaclor form clathrate-type complexes with a variety of naphthalene derivatives. The crystal structures of these complexes are isomorphous. Interestingly, the hosting framework formed by these cephalosporins can adapt to the guest molecule. This phenomenon of induced-fit appears to have a much larger potential, with the consequence that a series of smaller compounds (such as benzene derivatives) as well as bulkier compounds can also be hosted by Cephradine. When benzene derivatives were used as guests, pronounced deviations in the antibiotic framework were observed, and it is possible to induce deviations strikingly different from those found for the complexes with the naphthalene derivatives. Evidently, the hosting structure formed by Cephradine is highly flexible. Hosting frameworks containing layers, channels, and various other types of cavities can be obtained by selection of an appropriate guest molecule. Remarkably, a number of structural features and interactions remain unaffected in all these antibiotic frameworks. These persistent features seem to delineate the boundaries of framework formation for these antibiotics, thus defining the scope of complex formation.