Fluoranthene-Containing Distorted Nanographenes Exhibiting Two-Photon Absorption Response

Two distorted nanographenes combining helicenes and a fluoranthene unit within their polycyclic scaffolds were synthesized. Their structural and electronic properties were elucidated by various spectroscopic methods, and the experimental data were corroborated computationally. The optical and electrochemical properties of the nanographenes were evaluated. The compounds exhibit an improved two-photon absorption cross-section compared to their seven-membered ring-containing counterparts reported previously by us. These results provide important insights into how the incorporation of a pentagonal ring affects two-photon absorption properties of nanographenes. Moreover, one of the nanographenes is chiral and was obtained enantiomerically pure after chiral separation, allowing the study of its chiroptical properties both in absorption (electronic circular dichroism) and emission (circularly polarized luminescence).