Lipophilic Diamides as Ionophores for Alkali and Alkaline Earth Metal Cations

A series of lipophilic N, N, N′,N′‐tetrasubstituted diamides were prepared and their selectivity in solvent polymeric membranes was studied, cis‐N, N, N′, N′‐Tetraisobutylcyclohexane‐1,2‐dicarboxamide induces a selectivity in membranes for Li+over alkaline earth metal cations and other alkali metal cations by a factor of about 1000 and 100 respectively. The ionophore N, N′‐diheptyl‐N,N′‐dimethylethylmalonamide is an attractive candidate for the use in microelectrodes for the determination of intracellular Mg2+‐activities.