Solid State Complexes with Neutral Molecules

7 Complex Formation Involving Calixarenes 7.1 Solid State Complexes with Neutral Molecules 

Selective complexation has been demonstrated 132) by crystallizing p-tert-butyl-ealix[4]arene from 50 50 mixtures of two guest molecules such as benzene and p-xylene. It was found that anisole and p-xylene are complexed in preference to most other simple aromatic hydrocarbons. p-ter/-Butylcalix[4]arene has been shown to have some selectivity for mixtures of aromatic hydrocarbons when used as the immobile phase in a chromatographic column 133). 

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On the other hand, the so-called solid-state complexes of multiarmed podands (e.g., hexahosts) with neutral molecules are more likely to be classed with clathrates (crystal void inclusion compounds). ... 

Solid-state inclusion complexes of parent calixarenes with neutral molecules... 

Reaction of Au(tht)Cl with SbMes3 resulted, regardless of the molar ratio used, in the isolation of the neutral complex Au(SbMes3)Cl 118, which also contains a linear Sb-Au-Cl system (Figure 4.32d), with the shortest Au-Sb bond [2.5100(2) A] found so far in gold-stibine complexes. For none of these complexes was further association of the molecules observed in the solid state. 

Protein molecules fall within the limits of colloidal dimensions and are therefore subject to the same interfacial forces as polysaccharides. They too are amphilphilic—existing as zwitterions (internal salts) in water at neutral pH and in the solid state, and reacting chemically and physically with ionic and some nonionic molecules, often specifically (Hart et al., 1992). Their complexes have different bond strengths along with possibly different conformations (Dickinson and Euston, 1991a, b Mackie et al., 1991). 

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