Cyclic voltammetry (CV) and differential pulse voltammetry (DPV) measurements of cg-2 in dry CH2Cl2 revealed two successive redox waves, Ⅰ and Ⅱ with the half-wave potentials E1/2 at -0.21 V and 0 V (all values vs Fc/Fc + ), respectively (Fig. ). The redox waves Ⅰ and Ⅱ correspond to stepwise one-electron oxidations of cg-2 from its neutral diradical state to the radical cation state, then the dication state. These oxidation states were obtained by chemical oxidation with NO•SbF6 and characterized by UV-vis-NIR absorption spectroscopy (Fig. ). The neutral diradical state of cg-2 shows weak absorption bands at 675 nm and longer wavelengths region. According to timedependent DFT calculation, these weak absorption bands could be assigned to the forbidden transitions from SOMO-α to LUMO-α and SOMO-β to LUMO-β (Supplementary Fig. ). The radical cation and dication states of cg-2 exhibit similar absorption features: an intense band at 669 nm and a broad band centered at 1022 and 924 nm, respectively, indicating the structural similarity in their molecular orbitals related to electronic transitions (Supplementary Fig. ).