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arXiv · 2107.02198

On-surface synthesis and collective spin excitations of a triangulene-based nanostar

Jeremy Hieulle·Silvia Castro·Niklas Friedrich·Alessio Vegliante·Francisco Romero Lara·Sofía Sanz·Dulce Rey·Martina Corso·Thomas Frederiksen·Jose Ignacio Pascual·Diego Peña
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Abstract

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 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 {\pi}-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 a S = 1 spin ring, representing a unique system to test collective spin modes in cyclic systems.

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Jeremy Hieulle, Silvia Castro, Niklas Friedrich, Alessio Vegliante, Francisco Romero Lara, Sofía Sanz, Dulce Rey, Martina Corso, Thomas Frederiksen, Jose Ignacio Pascual, Diego Peña. 2021-07-05. On-surface synthesis and collective spin excitations of a triangulene-based nanostar. https://doi.org/10.1002/anie.202108301

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