Aryl carbazole-based macrocycles: synthesis, their remarkably stable radical cations and host–guest complexation with fullerenes

Abstract

A series of fully conjugated macrocycles M_n (n = 4–7) consisting of N-(3,5-di-tert-butyl-4-methoxyphenyl) substituted carbazole (Cz-Ar) were successfully synthesized. The aryl carbazole and macrocycle M₄ can be readily oxidized and the corresponding radical cation species were found to be highly stable. Moreover, macrocycle M₅ was found to form 1 : 1 stoichiometric complexes with fullerenes C₆₀ and C₇₀ with association constants as high as (8.38 ± 0.33) × 10⁴ M⁻¹ and (7.64 ± 0.26) × 10⁴ M⁻¹, respectively.