Construction of macrocycles via 1,3-position cyclization of carbazoles

A series of novel macrocyclic compounds containing 1,3-linked carbazole groups were synthesized via Friedel-Crafts reactions between 9-substituted difluorene diols with phenyl spacers and 9H-carbazoles. The photophysical and electrochemical properties of these macrocycles were briefly investigated. It is noteworthy that: (a) macrocyclic compounds featuring 1,3-linked carbazole groups have not been previously reported in the literature; (b) the cyclization of 9H-carbazoles at the 1,3 positions was facilitated by N–H···π interactions, as confirmed by single crystal X-ray analysis and control experiments; (c) the reactions were catalyzed by trifluoromethanesulfonic acid, resulting in moderate yields, demonstrating a simple and rapid synthetic route.