Toroidal inclusion complex

Similarily, toroidal inclusion complex (NH4) C [Co(OMe)2(02CMe)]g[PF5]) is isolated from the reaction between cobalt(III) acetate and methanol in the presence ofNH4PFe [59]. 

Cyclodextrins are bucketlike or conelike toroid molecules, with a rigid structure and a central cavity, the size of which varies according to the cyclodextrin type see Section 8. The internal surface of the cavity is hydrophobic and the outside of the torus is hydrophilic this is due to the arrangement of hydroxyl groups within the molecule. This arrangement permits the cyclodextrin to accommodate a guest molecule within the cavity, forming an inclusion complex. 

FIGURE 10.9 Cyclodextrin inclusion complexes. Toroidal units arranged with axes (a) parallel, (b) perpendicular to Zr(HP04)2 H2O layers and (c) nucleotide chain inside cycloamylose toroidal units. 

Cycloamyloses (cyclic a-l,4-linked oligomers of D-glucose) have a toroidal or doughnuf -shaped structure. The primary hydroxy groups are located on one side of the torus while the secondary ones lie on the other side. Relative to water the interior of the cycloamylose torus is apolar. The catalytic properties of cycloamyloses depend on the formation of inclusion complexes with the substrate and subsequent catalysis by either the hydroxy, or other groups, located around the circumference of the cavity (Komiyama and Bender, 1984 Page and Crombie, 1984). 

CyD is more or less toroidal in shape, i.e., shaped like a (thick-walled) bucket, with a hydrophobic cavity and hydrophihc exterior. This unique structure enables CyDs to form an inclusion complex, entrapping the whole, or part, of a guest molecule inside its cavity, principally by means of weak forces such as van der Waals forces, dipole-dipole interactions, and hydrogen bonding. The dimensions of the inner cavity of a-, P-, and y-CyDs are 5.7, 7.8, and 9.5A, respectively, thus potentially acconunodating a range of sizes of guest molecule [26]. 

This chapter reports and demonstrates, through inclusion of additional accurate numerical results of Greenspan [27] for complex body shapes such as cubes, ellipsoids, and circular and elliptical toroids, a lens that is formed by the intersection of two spheres such that Svj is a relatively weak function of the body shape and its aspect ratios. 

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