Receptor heterotopic

The stability of the polypyridyl rhenium(I) compounds mentioned above stimulated applications of this coordination chemistry. Thus, new heterotopic bis(calix[4]arene)rhenium(I) bipyridyl receptor molecules have been prepared and shown to bind a variety of anions at the upper rim and alkali metal cations at the lower rim. A cyclodextrin dimer, which was obtained by connecting two permethylated /3-cyclodextrins with a bipy ligand, was used for the preparation of a luminescent rhenium(I) complex. The system is discussed as a model conipound to study the energy transfer between active metal centers and a bound ditopic substrate. The fluorescence behavior of rhenium(I) complexes containing functionalized bipy ligands has been applied for the recognition of glucose. ... 

Heterotopic Coreceptors — Cyclophane Receptors, Amphiphilic Receptors, Large Molecular Cages... 

Reetz et al. have published a heterotopic receptor, which in addition to a crown ether moiety for complexation of potassium cations, contains a g-bonded Lewis acidic boron center that is able to form a tetracoordinated adduct with anions and with a selectivity for fluoride anions [ref 31]. Novel artificial polytopic receptors for binding of zwitterionic aminocarboxylates have been also published [ref 32]. 

Given that counterions must be extracted along with ions of interest into the membrane, efforts have been made to provide macrocyclic structures with the ability to associate directly with ions of both charges. Another example of a heterotopic receptor (31) from Smith s group is shown in... 

Figure 29 Cooperative inclusion of a cation and an anion in a heterotopic receptor. (Reproduced from Ref. 96. American Chemical Society, 2004.)...

The following part focuses on a number of heterotopic ion-pair receptors reported in the literature that feature simultaneous complexation of both cationic and anionic species. The combination of structural motifs used to coordinate the ionic species is the interpretative key that is principle to this session. 

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