Metal ion separations by proton-ionizable macrocylic and acyclic polyether ligands

Separation science is the part of chemical science that is concerned with separating different components of a mixture. Host-guest chemistry is a branch of chemistry that is concerned with the interaction between two or more entities that are held together by intermolecular forces. The larger entity, which normally accommodates the smaller one, is called the host and the smaller entity is referred to as the guest. For their pioneering work in the field of host-guest chemistry, C. J. Pedersen along with D. J. Cram and J.-M. Lehn were awarded the Nobel Prize in Chemistry in 1987.; Since their discovery by C. J. Pedersen in 1967, crown ethers have been employed in solvent extraction studies by many researchers during the past three decades. Crown ethers and related compounds are used for selective separation of metal cations. Structural modifications have led to crown ethers with improved selectivity and efficiency in metal ion separations. The solvent extraction results analyzed in this dissertation provide new insight into the influence of structural variations within proton-ionizable lariat ethers on the selectivity and efficiency of solvent extraction of alkali metal cations.; The polymeric inclusion membrane is a recent addition to the liquid membrane family. These membranes were first used by Sugiura and coworkers for the study of carrier-mediated transport of zinc ions in 1987. The application of proton-ionizable lariat ethers as metal ion carriers in polymer inclusion membranes has been pioneered by the Bartsch Research Group. The proton-ionizable lariat ethers analyzed in this dissertation shed light on several factors which affect the selectivity and efficiency of a carrier in competitive transport of alkali metal cations across polymeric inclusion membranes.; Acyclic polyethers have been used in the separation of alkali metal, alkaline earth metal, transition metal, and rare earth cations, as well as cationic species of many main group elements, such as lead, copper, mercury, bismuth, and cadmium. In this dissertation, it is shown that the acidity and structural variations within di-ionizable acyclic polyethers influence the selectivity and efficiency of a carrier in competitive transport of alkaline earth metal cations across polymeric inclusion membranes.