In collabration with Lu Jiong's group at NUS we reported the synthesis of an open-shell [7]triangulene quantum ring ([7]TQR) molecule on Au(111) through the surface-assisted cyclodehydrogenatio. Bond-resolved scanning tunneling microscopy (BR-STM) unambiguously imaged the molecular backbone of a single [7]TQR with a triangular zigzag edge topology, which can be viewed as [7]triangulene decorated with a coronene-like antidot in the center. Additionally, dI/dV mapping reveals that both inner and outer zigzag edges contribute to the edge-localized and spin-polarized electronic states of [7]TQR. Both experimental results and spin-polarized DFT and DMRG calculations indicate that [7]TQR retains its open-shell septuple ground state (S = 3) on Au(111). 
 

J. Su, W. Fan, P. Mutombo, X. Peng, Sh. Song, M. Ondráček, P. Golub, J. Brabec, L. Veis, M. Telychko, P. Jelínek, J. Wu, J. Lu
On-Surface Synthesis and Characterization of [7]Triangulene Quantum Ring

Nano Lett. 21 (2021) 861 - 867.