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 (K-a > 10(7) M-1). Ion-selective electrodes prepared with this naphthocage show a super-Nernstian response to acetylcholine. In addition, the highly stable complex (10(10) M-1) between ferrocenium and the naphthocage can be switched electrochemically, which lays a basis for its application in stimuli-responsive materials.