Highly contorted superhelicene hits near-infrared circularly polarized luminescence

Herein we describe a novel superhelicene structure consisting of three hexa-peri-hexabenzocoronene (HBC) units arranged in a helical geometry and creating two carbo[5]helicenes and a carbo[7]helicene. The central HBC bears a tropone moiety, which induces a saddle-helix hybrid geometry into the 3D structure of the prepared nanographene. The introduction of multiple helicenes and the position of the tropone unit trigger near-infrared circularly polarized luminescence (NIR-CPL, up to 850 nm, jglumj ¼ 3.0 10 3) combined with good photoluminescence quantum yields (fF ¼ 0.43) and upconverted emission based on two-photon absorption (TPA). Compared to previously reported superhelicenes of similar size, higher quantum yields, CPL brightness, and red-shifted absorption and emission spectra are achieved. Besides, chiroptical properties of enantiopure thin films were evaluated. These findings place this novel superhelicene as the first NIR-CPL superhelicene ever reported and make it a promising candidate for use as a chiral luminescent material in optoelectronic devices.European Research Council (ERC) 677023MCIN/AEI FEDER "Una manera de hacer Europa" PGC2018-101181-B-I00Spanish Government BES-2016-076371Fundacao para a Ciencia e a Tecnologiags UIDB/00100/2020 LA/P/0056/2020 PTDC/NAN-MAT/29317/2017 2020.01763.CEECIN