On?Surface Synthesis and Collective Spin Excitations of a Triangulene?Based Nanostar

Triangulene nanographenes are open-shell molecules with predicted high spin state due to the frustration of their conjugated network. Their long-sought synthesis became recently possible over a metal surface. Here, we present macrocycle formed by six [3]triangulenes, which was obtained combining solution dimethylphenyl-anthracene cyclic hexamer and on-surface cyclodehydrogenation this precursor gold substrate. The resulting triangulene nanostar exhibits collective generated interaction its 12 unpaired ?-electrons along lattice, corresponding antiferromagnetic ordering S=1 sites (one per unit). Inelastic electron tunneling spectroscopy resolved three excitations connecting singlet ground triplet states. behaves close predictions from Heisenberg model an ring, representing unique system test modes in systems.