Hieulle, JeremyCastro Fernández, SilviaFriedrich, NiklasVegliante, AlessioRomero-Lara, FranciscoSanz, SofíaRey Vieites, Dulce MaríaCorso, MartinaFrederiksen, ThomasPascual, Jose IgnacioPeña Gil, Diego2022-08-112022-08-112021Angew. Chem. Int. Ed. 2021, 60, 25224 – 25229. https://doi.org/10.1002/anie.2021083011433-7851http://hdl.handle.net/10347/29053Triangulene 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 a macrocycle formed by six [3]triangulenes, which was obtained by combining the solution synthesis of a dimethylphenyl-anthracene cyclic hexamer and the on-surface cyclodehydrogenation of this precursor over a gold substrate. The resulting triangulene nanostar exhibits a collective spin state generated by the interaction of its 12 unpaired π-electrons along the conjugated lattice, corresponding to the antiferromagnetic ordering of six S=1 sites (one per triangulene unit). Inelastic electron tunneling spectroscopy resolved three spin excitations connecting the singlet ground state with triplet states. The nanostar behaves close to predictions from the Heisenberg model of an S=1 spin ring, representing a unique system to test collective spin modes in cyclic systemseng©2021 The Authors. Angewandte Chemie International Edition published by Wiley-VCH GmbH. This is an open access article under the terms of the Creative Commons Attribution Non-Commercial NoDerivs License, which permits use and distribution in any medium, provided the original work is properly cited, the use is noncommercial and no modifications or adaptations are made.http://creativecommons.org/licenses/by-nc-nd/4.0/Bond-resolved STMOn-surface synthesisOpen-shellSpin excitationTriangulenejournal article10.1002/anie.2021083011521-3773open access