Neutral Molecules as Supramolecular Templates

An example of r-stacking as the driving force in a template synthesis is that by Hiinig et al. [15] of the cationic host molecule (cf. 11), which displays r-acceptor properties. In this case an increase in yield from 3-5% to 16% was observed when an excess of phenanthrene (as 7r-donor guest, see 11) was added to the reaction mixture. This example may even be considered as the first template effect 

New catenane (cf. 17) and rotaxane (cf. 20) types have been obtained via supramolecular template syntheses The amide-based interlocked structures can be designed by appropriate choice of building units (cf. 13, 14) to form stable out/out, in/in and in/out isomers (cf. 17a, 17b), which can be separated [19]. It can be demonstrated that one of the two macromonocycles (cf. 15) of the 

On the basis of the hypothesis of the intertwining mechanism described above, the syntheses of the first amide-based rotaxanes (Structures 20a, 20b) were successful as well [21], Their (supramolecular template) syntheses were strikingly simple. The central part of the axle 13a is added to a tetralactam wheel and subsequently capped with triphenylmethane stoppers. The macromonocycle ( wheel ) provides the receptor cavity for the axle and the stoppers confirm the mechanical bond between wheel and axle . 

Zinc(II) complexes of monomers and dimers derived from 1,4,7-triazacyclodo-decane 24 were recently examined by Breslow and co-workers [23] as catalysts 

The involvement of passive template effects and active acid-base interactions in catalyses of organic reactions is also described by Rebek and co-workers [24], 

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