Title

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

Date of Award

1987

Availability

Article

Degree Name

Doctor of Philosophy (Ph.D.)

Department

Chemistry

Abstract

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.

Keywords

Chemistry, Physical

Link to Full Text

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