Iron cryptates

We only list some other redox systems which have been proposed for the construction of solvent-independent reference electrodes. In the collection of such systems, one finds tris(2,2-bipyridine)iron(I)/(0) [69], tris(phenantroline)iron(III)/(II) [72], redox systems composed of polynuclear aromatic hydrocarbons [66, 71], 13 /I2 [72], and cryptate complexes [73, 74]. The use of these systems in practice is quite limited. 

The best possibility of identifying other effective chelators would appear to depend on devising new hexadentate structures, particularly cryptate systems. An improvement in the understanding of the metabolism of these chelating agents and their iron complexes will also help optimization of the structure. 

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