These azaheptalenes 1-3 were characterized by NMR spectroscopy and mass spectrometry and finally determined by single-crystal X-ray diffraction. X-ray analyses revealed that all azaheptalenes 1-3 adopt a highly distorted geometry with a dihedral angle [/° = 103.89 (11) for 1, 103.9(6) and 102.1 (7) for 2, and 100.3(5) for 3, respectively] between benzene rings on both sides (Figure ). These values were well-reproduced in optimized structures [/° = 104.0 for 1, 103.9 for 2, and 103.9 for 3, respectively] by density functional theory (DFT) calculations at the B3LYP/6-31G(d,p) level (Figure ). Since the dihedral angle  of helical nanographene C is 57.51(3) °, these helical azaheptalenes with much larger angles are expected to have higher racemization barriers to enable the successful isolation of both enantiomers of these azaheptalenes (vide infra). To investigate the redox properties of these azaheptalenes 1-3, we conducted cyclic voltammetry in CH 2 Cl 2 . A reversible one-electron oxidation wave was observed for all derivatives (Figure ), whereas both parent triphenylamine and N-phenyl tribenzoazepine gave an irreversible oxidation wave (Figure ). These results indicate that double ethenylene bridges certainly contribute to the stability of radical cation species. Next, we generated radical cation salts of these azaheptalenes. In fact, by treatment of dibromoazaheptalene 3 with one equivalent of (2,4-Br 2 C 6 H 3 ) 3 N +• SbCl 6 -(Magic Green), 3 +• SbCl 6 -was isolated in 79% yield as a dark green powder (Figure ). The structure of radical cation 3 +• was determined by X-ray analysis, where the dihedral angle  decreased from 100.3(5) ° to 92.95(10) ° upon oxidation (Figure ). The decrease in the dihedral angle can be accounted for by an effective delocalization of the spin and positive charge over the whole molecule. For non-and monobrominated derivatives 1 and 2, a generated radical cation was too reactive to be isolated. These results indicate that the introduction of bromine atoms into reactive sites is more effective for kinetic stabilization of radical cation species despite its electron-withdrawing properties (E 1/2 /V vs SCE: +1.39 for 1, +1.45 for 2, and +1.51 for 3). ).