Macrocyclic amides as ionophores for lead-selective membrane electrodes

A series of ionophores based on diaza 18-crown-6 units possessing amide and sulfonamide functions were prepared. Their complexing properties were inve stigated in solvent polymeric membrane electrodes. The influence of the str ucture of ligands, prepared on the selectivity of complexation, was examine d with special respect to lead ions. Substantial changes were observed, whe n methyl substituent in benzene rings was replaced with hydrogen, bromometh yl or nitro group. All results were rationalized on basis of steric and ele ctronic effects.