Self-assembly of Multitopic Macrocyclic Complexes

While the design and formation of self-assembled coordination cages described in the previous sections have received much attention, the corresponding metal-directed self-assembly of open multitopic receptors has been almost neglected so far. One reason is related to the need for partially derivatized precursors, which are synthetically more demanding than the corresponding fully derivatized ones. 

The first approach to the formation of a ditopic cavitand complex has been reported by Sorrell et al. [56]. They identified the tri-bridged resorcinarene as a 

To overcome this problem we switched to [Re(CO)5Br] as the metal precursor, because it is one of the few octahedral complexes that undergoes an exclusive cis ligand exchange, because of the remarkable trans effect of the carbonyl ligands. The replacement of two equatorial cis-CO groups gave the desired neutral 

Reduction of the exchange rate of the alkyldiammonium guest B compared to the alkylammonium A 

The inclusion of B takes place with a positive cooperative effect gained from the preorganization of the host 54. 

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