All azaheptalenes 1-3 could be separated by chiral HPLC on a Daicel CHIRALPAK IG (Chart S1). The 1st fraction exhibited a minus value of optical rotation (see SI), and the absolute configuration was finally determined to be P-helicity by X-ray analysis of 3 [Flack parameter:  = -0.060 (10)] (Figure ). The dihedral angle  of (P)-3 is 99.78(3) °, which is almost the same as that of (rac)-3. CD spectra of (P)-and ), which are much larger than those of helicene derivatives with a similar number of fused rings. Furthermore, the chiroptical properties can be switched upon oxidation. Indeed, by treatment of (P)-and (M)-3 with one equivalent of Magic Green, (P)-and (M)-3 +• SbCl 6 -were isolated in 42% and 52% yields, respectively. These radical cations with P-and M-helicity also displayed mirrorimage CD spectra even in the NIR region.