Undecabenzo[7]superhelicene: a helical nanographene ribbon as CPL emitter

Abstract

We report the synthesis and characterization of an enantiopure superhelicene nanographene constituted by two saddleshaped and one planar hexabenzocoronene (HBC) units arranged in a helicoidal shape. This is, to the best of our knowledge, the first undecabenzo[7]carbohelicene, i.e., the first fully π-extended [7]helicene. Racemic resolution allowed its chiroptical properties analysis revealing dissymmetry factors in the range of 2×10-3 both in the absorption and in the emission measurements. Remarkably, nonlinear photophysical analysis showed two-photon absorption crosssection of 870 GM at 800 nm and a perfect overlapping between linear, non-linear and chiral emission.