On-Surface Synthesis and Characterization of Super-nonazethrene

Beginning with the early work of Clar et al. in 1955, zethrenes and their laterally extended homologues, super-zethrenes, have been intensively studied solution phase widely investigated as optical charge transport materials. Superzethrenes are also considered to exhibit an open-shell ground state may thus serve model compounds investigate nanoscale π-magnetism. However, synthesis is extremely challenging due high reactivity. We report here on-surface hitherto largest zethrene homologue—super-nonazethrene—on Au(111). Using single-molecule scanning tunneling microscopy spectroscopy, we show that super-nonazethrene exhibits singlet featuring a large spin polarization-driven electronic gap 1 eV. Consistent emergence state, high-resolution spectroscopy reveals singlet–triplet excitations super-nonazethrene, characterized by strong intramolecular magnetic exchange coupling 51 meV. Given paucity chemistry on surfaces, our results therefore provide unprecedented access large, amenable probe measurements, potential application molecular spintronics.