Solvent Effects in Boronic Acid-Diol Binding

Boronic acids are notable for their ability to reversibly bind 1,2- and 1,3-diols in protic media. The utility of this reversible, selective, and covalent interaction has been exploited widely in supramolecular assemblies. However, little work has been done to explore the solvent dependence of boronic acid-diol condensations. Herein, we report an evaluation of association constants for commonly used phenylboronic acids and diols in different solvents. To this end, we employed UV-visual spectroscopy to monitor the extent of complexation using indicator-displacement assays in a series of host-guest titrations. We report multivariable correlations of the binding affinities to various solvent parameters and interpret the lessons thereof. By evaluating these binding affinities, we aim to (1) support the future design of supramolecular assemblies incorporating boronic acids and diols and (2) understand how solvent characteristics influence the association strength.