There have been many studies of crown compounds as neutral carriers of ion-selective electrodes. The investigations of these complexing agents have focused mainly upon obtaining high affinity and selectivity for given metal ions. When considering the coordination features of heavy metal cations such as Ag+, it is known that soft donor atoms in the host lonophores are more effective than just hard atom donors based on the hard-soft acid and base (HSAB) concept. One aspect of this thesis is to investigate the influence of nonionizable side arm which contain soft atom donor sites in sym-dibenzo- 16-crown lariat ethers upon their complexation and selectivities for silver ion versus alkali, alkaline-earth, transition, and heavy metal cations in solvent polymeric membrane electrodes. The second goal of this thesis is to obtain highly efficient Ag+ selective lonophores.