A facile two-step synthesis of azahelicenes possessing a 6-5-6-6-6-5-6 skeleton from commercially available 2,9-dichloro-1,10-phenanthroline via double amination with aniline derivatives followed by hypervalent iodine reagent-mediated intramolecular double-NH/CH couplings was developed. Single-crystal X-ray analyses of the helicenes revealed unique structures, including both a significantly twisted center and planar terminals of the skeleton. The azahelicenes show high fluorescent quantum yields (Φs) under both neutral (Φ: 0.25–0.55) and acidic conditions (Φ: up to 0.80). An enantiomerically pure azahelicene showed high circularly polarized luminescence (CPL) activity under both neutral and acidic conditions (glum: up to 0.009).
- X-ray diffraction
- circularly polarized luminescence
- oxidative coupling
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