Stable Double and Quadruple [5]Helicene Derivatives: Synthesis, Structural Analysis, and Physical Properties.

Two novel [5]helicene derivatives (labeled 5 and 8) have been successfully synthesized and characterized. The structural analyses, photophysical properties, along with density functional theory calculations for unveiling the helicity inversion and equilibrium of the diastereomers, were investigated in a comparative manner. In addition, chemical oxidation of them indicated that molecule 8 exhibited the formation of the radical cation at room temperature.