Host-guest complexes with a range of different structures

2 HOST-GUEST COMPLEXES WITH A RANGE OF DIFFERENT STRUCTURES 

Unique structures for host-guest systems are rare. In the examples given above, the position of guest within the host is sufficiently specific to persist in solution and in the solid state. The calculations described above were carried out in the gas phase but it is unlikely that the inclusion of solvent or of crystal packing will make any significant difference to the calculation as the structures investigated have uniquely low energy. 

In the general system, this is much less likely to be true and the neglect of solvent is likely to produce significant differences. However inclusion of specific solvent molecules leads to an enormous increase in computer time and while there are known methods for the inclusion of solvent effects in calculations [e.g. by including a distance related 

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