Synthesis of novel crown ether compounds and ionomer modification of Nafion
Lee, Jong Chan
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During the past two decades, much attention has been given to the design and synthesis of macrocyclic compounds capable of selective recognition for ionic species. Among them, crown ethers are finding many practical applications due to their unique metal ion complexation and transport ability. The major portion of this dissertation encompasses the development of new efficient cyclization methods for monobenzo- or dibenzocrown ethers as well as the synthesis of lariat ethers and the preparation of acyclic polyether compounds. A new cyclization method for aromatic ring containing crown ethers with various ring sizes is to be developed and evaluated by comparison with reported methods. Lariat ethers possessing high potential for complexation of either alkali or transition metal ions are to be synthesized by introduction of carefully chosen pendant side arm groups. Acyclic polyether carboxylic acids with methoxy donor groups which are useful for preparation of metal ion selective condensation polymers are to be prepared. The second portion of this dissertation is the chemical modification of Nafion® ionomer membrane which may be used to separate one ionic species from the others. The goal is to provide barrier layers on each side of the membrane through which metal ion permeation will be controlled by the identify of the ionic species. To achieve this goal, the feasibility of attaching ionophore molecules onto the surface of Nafion® perfluorosulfonic acid will be examined.