By the reaction with aromatic diamines, π-extended open-[60]fullerenes were synthesized, in which the nucleophilicity of the diamine switched annulation and orifice-cutting modes, thus generating a fused pyrazine or imidazole. Employing this method for [70]fullerene analogues, we synthesized the first π-extended [70]fullerenes exhibiting strong absorption behavior owing to the fused azaacene and 10π-elongation from the [60]fullerene core. The thus-formed 20-membered ring orifice realized the encapsulation of argon within the [70]fullerene cavity.