Ferrocene polyaza Oxa coronands and cryptands

A broad variety of aza-oxa coronands is known with ferrocene units bonded as side groups to the macrocycle in various modes. The ferrocene units can be connected by hydrocarbon bridges, 32-35, or by functional groups, 36-38 [80-84]. 

These ligands form different host-guest complexes, 39, and the redox potential of the ferrocene-ferricinium couple is sensitive to coronand complexation by alkali metals [84a]. 

Selective electrochemical recognition of mercury in water can be achieved with a ferrocene-functionalized 12-azacrown-4 derivative [84b]. 

Simultaneous cation-anion complexation, 40, is possible with appropriately constructed receptors. 

A tris-ferrocenyl coronand recognizes the ammonium cation in the presence of potassium X-ray diffraction analysis of the ammonium complex has revealed a host-guest relationship [81], 

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