Group clathrates

One important difference between the present and the previous case should be noted. For the hydroquinone clathrates, where the wall of a cavity consists of 12 OH groups, 6 adjacent carbon atoms, and 6 CH groups in ortho position to the OH groups, it seemed best to consider the product z qjk) as one unknown. For hydrates one may not do this the walls of both types of cavities consist exclusively of tetrahedrally-coordinated water molecules. Hence, one should use the same value of (,eg/k) —characteristic for a water molecule in a hydrate lattice—for both types of cavities and multi-... 

Carbon tetrachloride-hydrogen sulfide-water ternary system, 49, 51, 52 Carboniuin ion polymerization, 158 Carboxylic groups initiator, 174 Catalyst clathrates equilibrium, 35 Cell partition function, in calculation of thermodynamic quantities of clathrates, 26... 

Table 1 Types of Cd(CN)2 and related clathrates, space groups and examples.

Clathrate Host lattice Space group Examples for G... 

Further exploitation of the molecular shape feature has led more recently to the design of another series of clathrate hosts by substituting on the allene rigid backbone bulky groups 22>, Representative compounds of this new host family are 20 and 21. The allene 20 (R = t-butyl) shows an interesting clathration behaviour upon crystallization from various environments, including alicyclic and aromatic compounds, heterocycles, cyclic ketones and eyclohexaneamine 26>. 

Fig. 30. Schematic illustration of the 2 1 clathrate between N-tritylurea and dimethyl-formamide, showing the self-association of the host molecules along the b axis of the crystal (crystal data a — 29.614, b = 8.906, c = 16.127 A, p — 121.04°, space group Cc)23)...

Functional Group Assisted Clathrate Formation — Scissor-Like and Roof-Shaped Host Molecules... 

Functional Group Assisted Clathrate Formation 2.1 An Old Matter or a Missing Event ... 

Fig. 1. Constitutions of well-known clathrate (lattice inclusion) hosts equipped with polar (H-bond-active) functional groups...

Combining features typical of both complexes and clathrates (coordinatoclathrate) should provide new possibilities of host-guest control2). They are indicated by the relations specified in Fig. 8, e.g. chemoselectivity or selectivity for functional groups on the one hand, caused by the complex part, and on the other hand constitutional selectivity or selectivity for molecular size and expanse due to the clathrate branche of the diagrammatic family tree of a coordinatoclathrate shown in Fig. 8. 

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. 

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