Clathrates applications

Krypton clathrates have been prepared with hydroquinone and phenol. 85Kr has found recent application in chemical analysis. By imbedding the isotope in various solids, kryptonates are formed. The activity of these kryptonates is sensitive to chemical reactions at the surface. Estimates of the concentration of reactants are therefore made possible. Krypton is used in certain photographic flash lamps for high-speed photography. Uses thus far have been limited because of its high cost. Krypton gas presently costs about 30/1. 

Within this approach, clathrates (for a definition see Chapter 1 in Vol. 140 of this series) and related lattice-type aggregates may be considered as multi-supramolecular systems where guest molecules are included in a crystal matrix. They allow a great many applications which have been specified in Vol. 140, first of all the separation of enantiomers by enantioselective recognition and inclusion of racemic guest molecules. 

The possibility to resolve the two enantiomers of 27a (or 26) by crystalline complexa-tion with optically active 26 (or 27a) is mainly due to differences in topological complementarity between the H-bonded chains of host and guest molecules. In this respect, the spatial relationships which affect optical resolution in the above described coordination-assisted clathrates are similar to those characterizing some optically resolved molecular complexes S4). This should encourage additional applications of the lattice inclusion phenomena to problems of chiral recognition. 

To probe the range of application of the new inclusion strategy (coordination-assisted clathrate formation) in different ways, directed structural modifications were undertaken starting from the basic constitution 1, for instance as to the molecular skeleton (basic structure) and/or the sensor section (functional groups). The formulae 7-24 show different possibilities of such variations. 

Lunine, J.I., Stephenson, D.J. (1985). Thermodynamics of Clathrate Hydrate at Low and High Pressures with Application to the Outer Solar System. Astrophys. J. Suppl. Ser. 58,493-531. 

Carbajo, J.J., Mixed Clathrates for Cool Storage Applications, ONRL/TM-9530, pp. 1-24 (1985a). 

Cross-metathesis applications, 11, 200 enynes, 11, 282 in ethenolysis, 11, 198 Lewis-basic substrates, 11, 193 in one-pot reactions, 11, 197 for reagent synthesis, 11, 188 as simple metathesis reaction, 1, 171 Crotyltributyltins, with aldehydes, 9, 352 Crown ether clathrates, diorganozinc compounds, 2, 335 Crown ether-pendant polysilanes, preparation, 3, 577 Crown-ethers, as hosts, 12, 813... 

In addition to the use of existing hydrates, it has also been suggested that clathrate hydrates could find applications in storage and separation technology. Bardhun showed in 1962 the viable application of hydrates in desalination of sea water, while hydrates have also been investigated as a method for the storage and transport of methane without the use of high-pressure containers. 

Prussian blue was the first coordination polymer and has found extensive applications as a dye and ink. It has inspired the related Hoffman clathrates which are also CN bridged coordination polymers. In contrast Werner clathrates are based on discrete coordination complexes as the host but they do display some of the robustness of coordination polymers. 

The majority of the interest in liquid clathrates has centred around their potential applications in separation science, particularly in the separation of closely related species such as benzene and toluene, or xylene isomers (cf. zeolite-based methods, Section 9.2). Separation occurs as a result of the greater ability of one organic solvent over another to stabilise the liquid clathrate phase. Hence, in a... 

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