Hexa--benzocoronene with two extra K-regions in an -configuration.

There are three possible isomers for hexa--hexabenzocoronene (HBC) with two extra K-regions, but only two of them have been reported, namely with the - and -configurations. Herein, we describe the synthesis of HBC with two extra K-regions in the -configuration, forming a longer zigzag edge compared with the other two isomers. The structure of was validated by laser desorption/ionization time-of-flight mass analysis and nuclear magnetic resonance spectra, as well as Raman and infrared spectroscopies supported by density functional theory calculations. The optical properties of were investigated by UV/vis absorption and ultrafast transient absorption spectroscopy. Together with the analysis of aromaticity, the influence of the zigzag edge on the π-conjugation pathway and HOMO-LUMO gaps of the three isomers were investigated.