Cation Effects On The Electrochemistry Of Crown Ethers, Lariat Ethers And Podands

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Degree Name

Doctor of Philosophy (Ph.D.)




Molecular switching in macrocyclic polyether systems has been the subject of intense study during the past decade. The work conducted here utilizes a redox switching mechanism. The concept of redox or electrochemical switching in macrocyclic polyethers involves altering the cation binding properties of a ligand by electrochemical reduction of an electron deficient moiety attached to the ligand. Enhanced cation binding results from the intramolecular ion-pairing of the reduced moiety with the polyether-bound cation.This study was conducted on a series of anthraquinone-substituted podands (compounds 21-24, 27-29, 33-34), lariat ethers (compounds 25-26) and crown ethers (compounds 30-31) in the presence of Li('+), Na('+) and K('+). The electrochemical behavior of these systems in anhydrous acetonitrile was determined by cyclic voltammetric techniques. The anthraquinone moiety can undergo discrete one- and two-electron reductions. Cation effects were observed in both the anion radical and the dianion. The enhanced cation binding follows the order Li('+) > Na('+) > K('+).Binding studies were also performed on a variety of neutral nitrogen-pivot lariat ethers and bibracchial lariat ethers (compounds 9, 10, 13, 35-55) in acetonitrile. Silver, Li('+) and Na('+) binding constants (K(,S)) were determined by the potentiometric titration method. Some of the factors controlling Ag('+), Li('+) and Na('+) binding have been assessed.


Chemistry, Physical

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