Deborah A. Gustowski

Geometrical and electronic cooperativity in cation-mediated electrochemical reductions of anthraquinone-substituted podands

Abstract Unlike their nitroaromatic counterparts, podands based upon the anthraquinone skeleton bind cations more strongly when reduced because of a combination of geometrical and electronic factors.

Lariat ethers: from cation complexation to supramolecular assemblies

Lariat ethers are now well-known as macrocycles having one or more sidearms that contain donor groups and can interact with ring bound cations. Variations in structure and donor group arrangements lead to variation in cation binding strengths and selectivities. Such systems exhibit enhanced cation complexation and generally high complexation dynamics. The binding dynamics and strength may readily be altered by reductive switching. This process has been accomplished using both reducing metals and electrochemical techniques. Cyclic voltammetry and EPR techniques confirm the redox switching and the formation of intramolecular ion pairs. Redox-switched lariats have been utilized in cation transport through bulk liquid membranes. When the sidearms are highly lipophilic systems such as cholesteryl, they readily form completely synthetic lipid bilayers or micelles and can assemble into vesicle systems of considerable size and stability.

Electrochemical switching of lariat ethers: Enhanced cation binding by one- and two-electron reduction of an anthraquinone sidearm

The first example of cation binding enhancement by electrochemical switching in a lariat ether, accomplished by one- or two-electron reduction of a quinone sidearm, is presented.

Cation effects on the cyclic voltammograms of azotoluene and the potassium cation selectivity of the electrochemically reduced azo-cryptand 7,16-azobis(1,3-phenylenemethylene)-1,4,10,13-tetraoxa-7,16-diazaoctadecane

Azobenzenes are shown for the first time to exhibit substantial Li+ and Na+ cation effects on their electrochemical behaviour, and although K+ does not interact with Ar–NN–Ar, or its reduced form, a srong interaction is observed when K+ is bound as a cryptate complex.