Ion-paired templates

Photochemical Functionalizations by Complexed Benzophenones and Chlorinations Directed by Ion-paired Templates... 

Scheme 6-13 The doubly ion-paired template 26 gives high regioselectivity in the photochemical functionalization of 27, whereas the single ion-pairing substrates 28 and 29 are not functionalized with high specificity.

More recently, we have extended ion pairing to template-directed chlorination [15]. Since in the chlorination reactions HCl is produced, we could not use carboxyl-ate anions. However, ion pairs of substrate cations with iodoaryl templates carrying sulfonate anion groups directed chlorination with reasonably good selectivity. Somewhat poorer selectivity, because of flexibility, was achieved when the template carried the cationic group and the substrate was a sulfate anion. The ion paired template shows turnover catalysis by moving on to another substrate molecule after... 

Ion Pair Templation Strategies for Synthesis of Interlocked Molecules... 

Integrated Ion Pair Templation Using Ionic Components.178... 

The goal of this chapter is not to present an exhaustive collection of all of the research on this topic, but to provide a clear tutorial-style overview of the fundamental concepts aided by illustrative examples and informative schematics. Three types of ion pair templation strategies are described, namely, the use of integrated ionic components, the use of discrete ion templates, and traceless ion pair templation. These approaches can produce systems capable of two different functional behaviors by virtue of their synergistic properties. 

The most conceptually simple example of an ion pair templated synthesis involves an electrostatic association of oppositely charged components (Figure 10.4). After they are associated in the correct alignment, a suitable reaction can then be used to convert the ion pair assembly into a permanently interlocked product. 

In MeCN, host structure 11 exhibited significant emission spectral changes upon chloride and bromide complexation, while a large range of other relevant anions did not induce such responses. This impressive discrimination demonstrates the potential of ion pair templated interlocked hosts for application in molecular sensing devices. 

Receptors that bind both cations and anions can be employed for interlocked structure formation using a strategy best described as traceless ion pair templation. In this approach, such a receptor binds a reactive ion pair to produce a neutral product that retains neither of the templating ion pair parmers. The product—interlocked if appropriately designed components are used—does, however, retain its ion pair binding ability. 

SCFIEME 10.10 Synthesis of salt binding rotaxane 20 using macrocycle 17 and traceless ion pair templation. 

Since research into the templated synthesis of interlocked structures began over three decades ago, many strategies have been employed to produce, in ranarkably high yields, a multitude of diverse architectures with increasing complexity and supramolecular functionality. In this chapter, we described three successful ion pair templation strategies, specifically the use of integrated cationic and anionic components, discrete ion templates, and reactive ion pairs bound by macrocyclic receptors, all to mediate interlocked structure formation. 

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