Cryptands classification

Vogtle has suggested that synthetic ionophores be classified as follows (21) cor-onands are macromonocyclic compounds with any heteroatoms cryptands are bi- and polymacrocyclic ligands with any heteroatoms and podands are acyclic coronand and cryptand analogs. The term crown ether is reserved for coronands with only oxygens as heteroatoms. Such a classification will be used hereafter. 

Shape selective reactions are typically carried out over zeolites, molecular sieves and other porous materials. There are three major classifications of shape selectivity including (1) reactant shape selectivity where reactants of sizes less than the pore size of the support are allowed to enter the pores to react over active sites, (2) product shape selectivity where products of sizes smaller than the pore dimensions can leave the catalyst and (3) transition state shape selectivity where sizes of pores can influence the types of transition states that may form. Other materials like porphyrins, vesicles, micelles, cryptands and cage complexes have been shown to control product selectivities by shape selective processes. 

Zhang, X.X. Izatt. R.M. Bradshaw. J.S. Krakowiak, K.E. Approaches to improvement of metal ion selectivity by cryptands. Coord. Chem. Rev. 1998. 174, 179-189. MacGillivray, L.R. Atwood, J.L. Stmctural classification and general principle for the design of spherical molecular hosts. Angew. Chem. Int. Ed. 1999, 38. 1018-1033. 

Classification and Nomenclature of Supramolecular Compounds, p. 261 Concave Reagents, p. 3II Cryptands, p. 334... 

Carbohydrates, Recognition of, p. 169 Carbonic Anhydrase Models, p. 178 Carcerands and Hernicarcerands. p. 189 Cation-n Interactions, p. 214 Cavitands, p. 219 Chiral Guest Recognition, p. 236 Classical Descriptions of Inclusion Compounds, p. 253 Classification and Nomenclature of Supramolecular Compounds, p. 261 Clathrate Hydrates, p. 274 Conzplexation of Fullerenes, p. 302 Concepts in Ciystal Engineering, p. 319 Crown Ethers, p. 326 Cryptands, p. 334 Cryptophanes, p. 340 Cyclodextrins, p. 398... 

Weber. E. Vogtle, F. Classification and nomenclature of coronands, cryptands, podands. and their complexes. Inorg. Chim. Acta 1980. 45. L65-L67. 

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