Guest-mediated networks

The conversion from apohost to clathrate structure requires that the diol molecules can reversibly switch from a situation in which the host molecules interact with themselves (self-mediated network) to another in which they interact with the guests (guest-mediated network), with a concomitant rearrangement of geometric parameters d and A. 

As described earlier under "Analysis of apohost structures, the assembly of waad molecules is based on OH... X (X=N, anion, tt) or hydrogen bonds between host molecules, or can be mediated by the guest (G) via OH... G interactions. In the former case we define the strucmre as a self-mediated network, in the latter as a guest-mediated network (Scheme 4.4). 

Inorganic waad fran.y-[M(LOH)2X2] (M=Pd, Pt, X=C1, I, CH3COO, CH3) exploit this Venetian-blind mechanism to convert between the anion-mediated network of the apohost, sustained by OH... X hydrogen bonds, and the guest-mediated network based on OH... G hydrogen bonds [17], [25] . 

In this system it was found that all 72 hydrogen bonds are used to form the network that holds the capsule together (Fig. 31.4b). In this capsule there are 48 intermolecular hydrogen bonds and the capsule is formed without the mediation of water molecules. It was claimed that the fact that all the hydrogen bonds take part in the capsular network contribute to the observation that the guest is disordered in such capsules [24]. 

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