Coulomb repulsion between charges in the interlocked rings raises the energy required for additional oxidation, leading to four consecutive one-electron oxidation processes. This was confirmed by chemical titration of 1-Zn and 1 using NO•SbF₆, monitored by electronic absorption spectroscopy (Supplementary Figs. and). Similar titrations for OCT-1 and OCT-2 produced sequential oxidation up to the dication stage (Supplementary Figs. and).