Cryptands carbon bridgeheads

A variety of other cryptand derivatives have been reported. Two systems incorporating carbon bridgeheads are (215) (Coxon Stoddart,... 

The crystal structures of a number of cryptands with bridgehead carbon, as opposed to nitrogen, atoms have also been reported (81CC729). 

Thus, it is the polyazamacrocyclic ligands developed by Lehn which have proved to be the most successful and versatile cryptands, rather than those carbon-bridgehead cryptands sought initially by Stoddart (25-27) which define a spheroidal cavity (e.g., 6). On the other hand, the bridged macrocyclic polyethers developed by Parsons (28), such as 7, show high complexing ability with alkali metal cations (28-30)... 

In the potassium cryptate with the carbon-bridgehead cryptand di-... 

The earliest molecules designed specifically to encapsulate other species were of a type now known as cryptands, including sepulchrates and sarcophagenes, and have been described in Chapter 1. These compounds make use of two bridgehead atoms, often carbon, nitrogen or boron, which are linked by three molecular strands. These molecules are intentionally quite flexible to allow small guests to enter but, once inside, donor atoms within the strands surround the guests with numerous weak... 

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