Ring-Expansion Strategy for α-Aryl Azahelicene Construction: Building Blocks for Optoelectronic Materials

An acid-mediated rapid synthesis of alpha-aryl azahelicenes via C-C bond cleavage of helical 9H-fluoren-9-ols is reported. The newly introduced aryl ring and pyridine moieties provide an excellent opportunity to further tune the properties of azahelicences: i.e., photoluminescence. The novel alpha-aryl azahelicenes showcase high circularly polarized luminescence (CPL) efficiencies (4.5 x 10(-3)) as well as CPL brightness (BCPL), reaching 7.39 M-1 cm(-1), which indicates a potential application as chiral emitters.

Automated summary

This research reports a method of rapid synthesis of alpha-aryl azahelicenes through C-C bond cleavage of helical 9H-fluoren-9-ols, providing an excellent opportunity to further adjust the photoluminescence properties through the introduction of new aryl rings and pyridine moieties. The novel alpha-aryl azahelicenes exhibit high circularly polarized luminescence efficiencies and brightness, indicating a potential application as chiral emitters.