Solid-state host-guest compounds

The host in a clathrate is the entire (usually crystalline) solid and the gnest binding cavity does not need to be an intrinsic property of the individual host molecules. 

Clathrates can often be non-stoichiometric corresponding to cases in which not all of the voids in the crystal are filled by guests. 

Supramolecular Chemistry, 2nd edition J. W. Steed and J. L. Atwood 2009 John Wiley Sons, Ltd ISBN 978-0-470-51233-3 

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Solid state host-guest compounds or clathrates are examples of co-crystals where the host packs in such a way as to leave a gap in the crystal lattice suitable for inclusion of the guest. 

Clathrates solid state host-guest compounds, consisting of a network of self-associating molecules forming cavities or charmels in which guest species can reside. They are usually only stable in the presence of guest species. 

In solid-state host-guest or clathrate compounds the guest is included within a gap in the packing of... 

Solvates are solid-state host-guest complexes in which solvent molecules are included into the interstitial spaces, cavities, and channels of other molecules as a result of crystallization. When the included solvent is water, the term hydrate applies. The ability of a compound to form solvates... 

Numerous channel structures of host-guest compounds are known that owe their channel structure to the inclusion. Filled channels are not the subjects of this section, but displacement of guests by reagents followed by solid-state reaction might also be envisioned in channels that are engineered by inclusion. 

The predominant importance of the cations in zeolites is that they form so-called active sites for selective interaction with guest molecules in sorption and catalytic processes. From the point of view of advanced material science [47] they play a significant role in the formation of quantum-sized clusters with novel optical or semiconducting properties. As they give rise to cationic conductivity, zeolites can be used as solid electrolytes, membranes in ion-selective electrodes and as host structures in solid-state batteries. Organometallic compounds and coordination complexes can be readily formed on these cations within the larger cages or channels and applied to gas separation, electron-transport relays and hybrid as well as shape-selective catalysis [48]. 

The previous hosts produced host-guest compounds that usually exist in solution and in the solid state. By way of contrast inclusion compounds of a so-called solid-state host are only in existence in the solid state. As stated... 

Solid-state inclusion chemistry concerns the formation of host-guest compounds, their characterization by means of an extensive arsenal of analytical techniques, and their description. In most cases, guest molecules occupy lattice sites in crystals and it is therefore possible to obtain accurate crystallographic information regarding their locations within the guest-accessible spaces formed by the host framework. These spaces may consist of cavities or channels, and a number of computer programs are now able to map the surfaces that define the boundaries of the guest-accessible volume. Channels can be one-, two-, or three-dimensional (two- and three-dimensional channels... 

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