An azonia derivative of hexahelicene

In 8a-azonia[6]helicene hexafluorophosphate or 8a-azoniaphenanthro[3,4-c]phenanthrene hexafluorophosphate, C25H16N+.PF6- , replacement of an outer bridgehead carbon of hexahelicene by a quaternary Nsp(2) atom results in a geometrical change in the helical structure. The racemic heterohelicene forms homochiral columnar stacks through intermolecular pi-pi donor-acceptor interactions in the crystalline state.