A pH-Responsive Synthetic Receptor for Switchable Binding of Carbohydrates.

Stimuli-responsive, water-soluble synthetic receptors are key to advancing dynamic molecular recognition in aqueous environments, with implications for self-assembly, molecular machines, and biomedical systems. Herein, a macrocyclic receptor is reported that exhibits pH-dependent binding properties toward saccharides in water, in that it displays markedly different affinities between alkaline and neutral conditions. Spectroscopic and binding studies reveal that the degree of protonation of the solubilizing groups modulates the receptor self-association phenomena, together with concomitant substantial loss of binding ability. This work highlights a rare example of a pH-switchable carbohydrate receptor operating in water and underscores the potentials of such system in the design of smart, responsive molecular architectures.