Non-benzenoid high-spin polycyclic hydrocarbons generated by atom manipulation

Abstract

We report the on-surface synthesis of a non-benzenoid triradical through dehydrogenation of truxene (C27H18) on coinage metal and insulator surfaces. Voltage pulses applied via the tip of a combined scanning tunneling microscope/atomic force microscope were used to cleave individual C-H bonds in truxene. The resultant final product truxene-5,10,15-triyl (1) was characterized at the single-molecule scale using a combination of atomic force microscopy, scanning tunneling microscopy and scanning tunneling spectroscopy. Our analyses show that 1 retains its open-shell quartet ground state, predicted by density functional theory, on a two monolayer-thick NaCl layer on a Cu(111) surface. We image the frontier orbital densities of 1 and confirm that they correspond to spin-split singly occupied molecular orbitals. Through our synthetic strategy, we also isolate two reactive intermediates toward the synthesis of 1 - derivatives of fluorenyl radical and indeno[1,2-a]fluorene, with predicted spin-doublet and spin-triplet ground states, respectively. Our results should have bearings on the synthesis of non-benzenoid high-spin polycyclic frameworks with magnetism beyond Lieb's theorem.

arXiv comment8 pages, 5 figures and supporting information containing additional data

References in corpus (6)

• On-surface synthesis of graphene nanoribbons with zigzag edge topology
• Emergence of magnetism in graphene materials and nanostructures
• Collective All-Carbon Magnetism in Triangulene Dimers
• On-surface synthesis and collective spin excitations of a triangulene-based nanostar
• On-surface synthesis of antiaromatic and open-shell indeno[2,1-b]fluorene polymers and their lateral fusion into porous ribbons
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Cited by in corpus (5)

• Bistability between $\pi$-diradical open-shell and closed-shell states in indeno[1,2-a]fluorene
• Conformational tuning of magnetic interactions in coupled nanographenes
• On-surface Synthesis of a Ferromagnetic Molecular Spin Trimer
• Magnetic frustration and fractionalization in oligo(indenoindenes)
• Hyperfine interactions in open-shell planar $s{p}^2$-carbon nanostructures