Naphthocage: A Flexible yet Extremely Strong Binder for Singly Charged Organic Cations

We report a quite flexible naphthol-based cage (so-called “naphthocage”) which adopts a self-inclusion conformation in its free state and is able to bind singly charged organic cations extremely strongly (Ka > 107 M–1). Ion-selective electrodes prepared with this naphthocage show a super-Nernstian response to acetylcholine. In addition, the highly stable complex (1010 M–1) between ferrocenium and the naphthocage can be switched electrochemically, which lays a basis for its application in stimuli-responsive materials.