Definitions and Synthesis

Carcerand 6.97 was designed by Cram s group, just as they had designed the spherands, with the aid of CPK molecular models. In his Nobel Prize address, writing just two years after the preparation of 6.97, Cram describes his interest in the host-guest chemistry of this new capsule  

The first question to be answered was what guest compound would be trapped inside during the shell closure This question is akin to asking whether two soup bowls closed rim-to-rim under the surface of a kettle of stew would net any stew. The answer was that [6.97] contained essentially every kind of component of the medium present during ring closure.  

Since the preparation of 6.97, an enormous range of carcerand and hemicarcerand species have been prepared based upon both [n]resorcarenes and calix[n]arenes (n = 4,5), all of which exhibit interesting binding behaviour and intra-cavity reactivity, as we will see in the next sections. 

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