Molecular selectivity and cooperativity in the clathrate-type complexation of cephradine
Kemperman GJ, de Gelder R, Dommerholt FJ, Klunder AJH, Zwanenburg B
EUROPEAN JOURNAL OF ORGANIC CHEMISTRY (2): 345-350 JAN 2002

Abstract:
The cephalosporin antibiotic cephradine can form clathrate-type complexes with appropriate guest molecules. When a mixture of o- and p-disubstituted benzene derivatives is subjected to complexation with cephradine, a high preference and in some cases complete selectivity for one isomer is shown by the host molecule. It is demonstrated that clathration with cephradine is an effective method for the separation of o and p isomers. Another interesting feature is observed when a cocktail of appropriate guest molecules is used in the complexation with cephradine. The observed preference for inclusion of more than one type of complexing agent strongly points to a cooperative effect of guest molecules in the resulting complex. This cooperative effect, however, does not result in more efficient complexation - that is, a lower residual concentration of the antibiotic - which is desirable for industrial applications.