14-Crown-4 ionophores, lithium selective

Many other cyclic and noncyclic organic carriers with remarkable ion selectivities have been used successfiilly as active hosts of various liquid membrane electrodes. These include the 14-crown-4-ether for lithium (30) 16-crown-5 derivatives for sodium bis-benzo-18-crown-6 ether for cesium the ionophore ETH 1001 [(R,R)-AA -bisd l-ethoxycarbonyl)undecyl-A,yVl-4,5-tctramcthyl-3,6-dioxaoctancdiamide] for calcium the natural macrocyclics nonactin and monensin for ammonia and sodium (31), respectively the ionophore ETH 1117 for magnesium calixarene derivatives for sodium (32) and macrocyclic thioethers for mercury and silver (33). 

The transport of alkali and alkaline earth metal cations by many crown ethers and their derivatives has been extensively studied. Much effort has been paid to increase their selectivity as well as their efficiency. Making highly Li selective ionophores is a primary concern in this field, because large quantities of lithium could be extracted from sea water for use to nuclear fusion generators... 

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