The double-armed diazacrown ethers, which have a base diazacrown ether ring with two diamide-type side chains, were designed and synthesized on the basis of the proposed molecular model for the novel neutral Ca2+ and Mg2+ ionophores. The potentiometric ion- selective electrodes were prepared with over 20 kinds of systematically synthesized diazacrown ether derivatives. The relationship between the molecular structures of the ...