Incorporation of Lewis acids into heterobimetallic complexes has emerged as an attractive strategy for modulating the thermochemical properties of redox-active compounds. In recent work, we demonstrated that such Lewis acid effects can be effectively leveraged to modulate the redox properties of the uranyl ion (UO22+) through the use of tailored macrocyclic ligands. Work with a series of compounds containing homologous UVI(μ-OAr)2Mn+ cores assembled with a range of Lewis acids (Mn+) contained in a pendant 18-crown-6-like site showed that the UVI/UV reduction potential shifts positive and that the rate of electron transfer decreases with increasing Lewis acidity. The role of the crown ether site’s structure has not previously been explored, however, offering the opportunity to better understand how Lewis acid coordination drives these important effects. In this talk, new findings for tailored macrocyclic ligands that present either an 18-crown-6- or 15-crown-5-like site will be discussed. The results suggest that the supramolecular preference for ion binding in these receptors has a profound influence over the redox chemistry of the nearby UO22+ moiety, and that supramolecular effects could be usefully considered for the development of next-generation approaches to uranium handling and redox cycling.

Using supramolecular preferences and Lewis acidity to influence uranium redox cycling

ACS Spring Meeting 2021

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