The synthesis and characterization of an enantiopure superhelicene nanographene is reported in which two saddle-shaped and one planar hexabenzocoronene (HBC) units are arranged in a helicoidal shape to form an undecabenzo[7]carbohelicene. The described compound is the first fully π-extended [7]helicene. Racemic resolution of the helical nanographene permitted analysis of the chiroptical properties and revealed dissymmetry factors in the range of 2×10-3 both in the absorption and in the emission measurements. Remarkably, non-linear photophysical analysis demonstrated a two-photon absorption cross-section of 870 GM at 800 nm and a perfect overlap between linear, non-linear, and chiral emissions.
Keywords: circularly polarized luminescence; helicenes; nanostructures; nonlinear optics; photophysics.
© 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.