The zigzag-edged triangular graphene molecules (ZTGMs) have been predicted to host ferromagnetically coupled edge states with the net spin scaling with the molecular size, which affords large spin tunability crucial for next-generation molecular spintronics. However, the scalable synthesis of large ZTGMs and the direct observation of their edge states have been long-standing challenges because of the molecules' high chemical instability. Here, we report the bottom-up synthesis of π-extended [5]triangulene with atomic precision via surface-assisted cyclodehydrogenation of a rationally designed molecular precursor on metallic surfaces. Atomic force microscopy measurements unambiguously resolve its ZTGM-like skeleton consisting of 15 fused benzene rings, while scanning tunneling spectroscopy measurements reveal edge-localized electronic states. Bolstered by density functional theory calculations, our results show that [5]triangulenes synthesized on Au(111) retain the open-shell π-conjugated character with magnetic ground states.

Centre for Advanced 2D Materials National University of Singapore 6 Science Drive 2 Singapore 117546 Singapore

Department of Chemistry National University of Singapore 3 Science Drive 3 Singapore 117543 Singapore

Department of Physics National Sun Yat sen University Kaohsiung 80424 Taiwan

Institute of Physics Academia Sinica Taipei 11529 Taiwan

Institute of Physics The Czech Academy of Sciences Prague 16200 Czech Republic

NUS Graduate School for Integrative Sciences and Engineering National University of Singapore 28 Medical Drive Singapore 117456 Singapore

Regional Centre of Advanced Technologies and Materials Palacký University Olomouc 78371 Czech Republic

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Clar E., Stewart D. G., Aromatic hydrocarbons. LXV. Triangulene derivatives. J. Am. Chem. Soc. 75, 2667–2672 (1953).

Melle-Franco M., When 1 + 1 is odd. Nat. Nanotechnol. 12, 292–293 (2017). PubMed

Morita Y., Suzuki S., Sato K., Takui T., Synthetic organic spin chemistry for structurally well-defined open-shell graphene fragments. Nat. Chem. 3, 197–204 (2011). PubMed

Lieb E., Two theorems on the Hubbard model. Phys. Rev. Lett. 62, 1201–1204 (1989). PubMed

Potasz P., Güçlü A. D., Hawrylak P., Zero-energy states in triangular and trapezoidal graphene structures. Phys. Rev. B. 81, 033403 (2010).

Fernández-Rossier J., Palacios J. J., Magnetism in graphene nanoislands. Phys. Rev. Lett. 99, 177204 (2007). PubMed

Wang W. L., Meng S., Kaxiras E., Graphene nanoflakes with large spin. Nano Lett. 8, 241–245 (2008). PubMed

Castro Neto A. H., Guinea F., Peres N. M. R., Novoselov K. S., Geim A. K., The electronic properties of graphene. Rev. Mod. Phys. 81, 109–162 (2009).

Wang W. L., Yazyev O. V., Meng S., Kaxiras E., Topological frustration in graphene nanoflakes: Magnetic order and spin logic devices. Phys. Rev. Lett. 102, 157201 (2009). PubMed

Han W., Kawakami R. K., Gmitra M., Fabian J., Graphene spintronics. Nat. Nanotechnol. 9, 794–807 (2014). PubMed

Pavliček N., Mistry A., Majzik Z., Moll N., Meyer G., Fox D. J., Gross L., Synthesis and characterization of triangulene. Nat. Nanotechnol. 12, 308–311 (2017). PubMed

Cai J., Ruffieux P., Jaafar R., Bieri M., Braun T., Blankenburg S., Muoth M., Seitsonen A. P., Saleh M., Feng X., Müllen K., Fasel R., Atomically precise bottom-up fabrication of graphene nanoribbons. Nature 466, 470–473 (2010). PubMed

Ruffieux P., Wang S., Yang B., Sánchez-Sánchez C., Liu J., Dienel T., Talirz L., Shinde P., Pignedoli C. A., Passerone D., Dumslaff T., Feng X., Müllen K., Fasel R., On-surface synthesis of graphene nanoribbons with zigzag edge topology. Nature 531, 489–492 (2016). PubMed

Chen Y.-C., Cao T., Chen C., Pedramrazi Z., Haberer D., de Oteyza D. G., Fischer F. R., Louie S. G., Crommie M. F., Molecular bandgap engineering of bottom-up synthesized graphene nanoribbon heterojunctions. Nat. Nanotechnol. 10, 156–160 (2015). PubMed

Treier M., Pignedoli C. A., Laino T., Rieger R., Müllen K., Passerone D., Fasel R., Surface-assisted cyclodehydrogenation provides a synthetic route towards easily processable and chemically tailored nanographenes. Nat. Chem. 3, 61–67 (2011). PubMed

Cai J., Pignedoli C. A., Talirz L., Ruffieux P., Söde H., Liang L., Meunier V., Berger R., Li R., Feng X., Müllen K., Fasel R., Graphene nanoribbon heterojunctions. Nat. Nanotechnol. 9, 896–900 (2014). PubMed

Nguyen G. D., Tsai H.-Z., Omrani A. A., Marangoni T., Wu M., Rizzo D. J., Rodgers G. F., Cloke R. R., Durr R. A., Sakai Y., Liou F., Aikawa A. S., Chelikowsky J. R., Louie S. G., Fischer F. R., Crommie M. F., Atomically precise graphene nanoribbon heterojunctions from a single molecular precursor. Nat. Nanotechnol. 12, 1077–1082 (2017). PubMed

Talirz L., Söde H., Cai J., Ruffieux P., Blankenburg S., Jafaar R., Berger R., Feng X., Müllen K., Passerone D., Fasel R., Pignedoli C. A., Termini of bottom-up fabricated graphene nanoribbons. J. Am. Chem. Soc. 135, 2060–2063 (2013). PubMed

Giessibl F. J., Advances in atomic force microscopy. Rev. Mod. Phys. 75, 949–983 (2003).

Mohn F., Schuler B., Gross L., Meyer G., Different tips for high-resolution atomic force microscopy and scanning tunneling microscopy of single molecules. Appl. Phys. Lett. 102, 073109 (2013).

Gross L., Mohn F., Moll N., Liljeroth P., Meyer G., The chemical structure of a molecule resolved by atomic force microscopy. Science 325, 1110–1114 (2009). PubMed

Giessibl F. J., High-speed force sensor for force microscopy and profilometry utilizing a quartz tuning fork. Appl. Phys. Lett. 73, 3956–3958 (1998).

Gross L., Recent advances in submolecular resolution with scanning probe microscopy. Nat. Chem. 3, 273–278 (2011). PubMed

Hapala P., Kichin G., Wagner C., Tautz F. S., Temirov R., Jelínek P., Mechanism of high-resolution STM/AFM imaging with functionalized tips. Phys. Rev. B. 90, 085421 (2014). PubMed

Pavlicěk N., Majzik Z., Collazos S., Meyer G., Peŕez D., Guitiań E., Peña D., Gross L., Generation and characterization of a meta-aryne on Cu and NaCl Surfaces. ACS Nano 11, 10768–10773 (2017). PubMed

Schule B., Fatayer S., Mohn F., Moll N., Pavliček N., Meyer G., Peña D., Gross L., Reversible Bergman cyclization by atomic manipulation. Nat. Chem. 8, 220–224 (2016). PubMed

Randić M., Aromaticity of polycyclic conjugated hydrocarbons. Chem. Rev. 103, 3449–3605 (2003). PubMed

Kimouche A., Ervasti M. M., Drost R., Halonen S., Harju A., Joensuu P. M., Sainio J., Liljeroth P., Ultra-narrow metallic armchair graphene nanoribbons. Nat. Commun. 6, 10177 (2015). PubMed PMC

Rizzo D. J., Veber G., Cao T., Bronner C., Chen T., Zhao F., Rodriguez H., Louie S. G., Crommie M. F., Fischer F. R., Topological band engineering of graphene nanoribbons. Nature 560, 204–208 (2018). PubMed

Ezawa M., Metallic graphene nanodisks: Electronic and magnetic properties. Phys. Rev. B 76, 245415 (2007).

Chen C. J., Tunneling matrix elements in three-dimensional space: The derivative rule and the sum rule. Phys. Rev. B 42, 8841–8857 (1990). PubMed

Krejčí O., Hapala P., Ondráček M., Jelínek P., Principles and simulations of high-resolution STM imaging with a flexible tip apex. Phys. Rev. B 95, 045407 (2017).

Ruffieux P., Cai J., Plumb N. C., Patthey L., Prezzi D., Ferretti A., Molinari E., Feng X., Müllen K., Pignedoli C. A., Fasel R., Electronic structure of atomically precise graphene nanoribbons. ACS Nano 6, 6930–6935 (2012). PubMed

Zheng Y. J., Huang Y. L., Chen Y., Zhao W., Eda G., Spataru C. D., Zhang W., Chang Y.-H., Li L.-J., Chi D., Quek S. Y., Wee A. T. S., Heterointerface screening effects between organic monolayers and monolayer transition metal dichalcogenides. ACS Nano 10, 2476–2484 (2016). PubMed

Neaton J. B., Hybertsen M. S., Louie S. G., Renormalization of molecular electronic levels at metal-molecule interfaces. Phys. Rev. Lett. 97, 216405 (2006). PubMed

Chen Y.-C., de Oteyza D. G., Pedramrazi Z., Chen C., Fischer F. R., Crommie M. F., Tuning the band gap of graphene nanoribbons synthesized from molecular precursors. ACS Nano 7, 6123–6128 (2013). PubMed

Liu Z.-F., Egger D. A., Refaely-Abramson S., Kronik L., Neaton J. B., Energy level alignment at molecule-metal interfaces from an optimally tuned range-separated hybrid functional. J. Chem. Phys. 146, 092326 (2017).

Bartels L., Meyer G., Rieder K.-H., Controlled vertical manipulation of single CO molecules with the scanning tunneling microscope: A route to chemical contrast. Appl. Phys. Lett. 71, 213–215 (1997).

Perdew J. P., Burke K., Ernzerhof M., Generalized gradient approximation made simple. Phys. Rev. Lett. 77, 3865–3868 (1996). PubMed

Kohn W., Sham L. J., Self-consistent equations including exchange and correlation effects. Phys. Rev. 140, A1133–A1138 (1965).

Kresse G., Joubert D., From ultrasoft pseudopotentials to the projector augmented-wave method. Phys. Rev. B 59, 1758–1775 (1999).

Kresse G., Hafner J., Ab initio molecular dynamics for liquid metals. Phys. Rev. B 47, 558–561 (1993). PubMed

Kresse G., Furthmüller J., Efficient iterative schemes for ab initio total-energy calculations using a plane-wave basis set. Phys. Rev. B 54, 11169–11186 (1996). PubMed

Hohenberg P., Kohn W., Inhomogeneous electron gas. Phys. Rev. 136, B864–B871 (1964).

Krukau A. V., Vydrov O. A., Izmaylov A. F., Scuseria G. E., Influence of the exchange screening parameter on the performance of screened hybrid functionals. J. Chem. Phys. 125, 224106 (2006). PubMed

Shishkin M., Kresse G., Implementation and performance of the frequency-dependent GW method within the PAW framework. Phys. Rev. B 74, 035101 (2006).

Shishkin M., Kresse G., Self-consistent GW calculations for semiconductors and insulators. Phys. Rev. B 75, 235102 (2007). PubMed

Shishkin M., Marsman M., Kresse G., Accurate quasiparticle spectra from self-consistent GW calculations with vertex corrections. Phys. Rev. Lett. 99, 246403 (2007). PubMed

Fuchs F., Furthmüller J., Bechstedt F., Shishkin M., Kresse G., Quasiparticle band structure based on a generalized Kohn-Sham scheme. Phys. Rev. B 76, 115109 (2007).

Klimeš J., Bowler D. R., Michaelides A., Chemical accuracy for the van der Waals density functional. J. Phys. Condens. Matter 22, 022201 (2010). PubMed

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