1
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Vegliante A, Fernández S, Ortiz R, Vilas-Varela M, Baum TY, Friedrich N, Romero-Lara F, Aguirre A, Vaxevani K, Wang D, Garcia Fernandez C, van der Zant HSJ, Frederiksen T, Peña D, Pascual JI. Tuning the Spin Interaction in Nonplanar Organic Diradicals through Mechanical Manipulation. ACS NANO 2024. [PMID: 39304184 DOI: 10.1021/acsnano.4c01963] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 09/22/2024]
Abstract
Open-shell polycyclic aromatic hydrocarbons (PAHs) represent promising building blocks for carbon-based functional magnetic materials. Their magnetic properties stem from the presence of unpaired electrons localized in radical states of π character. Consequently, these materials are inclined to exhibit spin delocalization, form extended collective states, and respond to the flexibility of the molecular backbones. However, they are also highly reactive, requiring structural strategies to protect the radical states from reacting with the environment. Here, we demonstrate that the open-shell ground state of the diradical 2-OS survives on a Au(111) substrate as a global singlet formed by two unpaired electrons with antiparallel spins coupled through a conformational-dependent interaction. The 2-OS molecule is a "protected" derivative of the Chichibabin's diradical, featuring a nonplanar geometry that destabilizes the closed-shell quinoidal structure. Using scanning tunneling microscopy (STM), we localized the two interacting spins at the molecular edges, and detected an excited triplet state a few millielectronvolts above the singlet ground state. Mean-field Hubbard simulations reveal that the exchange coupling between the two spins strongly depends on the torsional angles between the different molecular moieties, suggesting the possibility of influencing the molecule's magnetic state through structural changes. This was demonstrated here using the STM tip to manipulate the molecular conformation, while simultaneously detecting changes in the spin excitation spectrum. Our work suggests the potential of these PAHs as all-carbon spin-crossover materials.
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Affiliation(s)
| | - Saleta Fernández
- Centro Singular de Investigación en Química Biolóxica e Materiais Moleculares (CiQUS) and Departamento de Química Orgánica, Universidade de Santiago de Compostela 15782 Santiago de Compostela, Spain
| | - Ricardo Ortiz
- Donostia International Physics Center (DIPC), 20018 Donostia-San Sebastián, Spain
| | - Manuel Vilas-Varela
- Centro Singular de Investigación en Química Biolóxica e Materiais Moleculares (CiQUS) and Departamento de Química Orgánica, Universidade de Santiago de Compostela 15782 Santiago de Compostela, Spain
| | - Thomas Y Baum
- Kavli Institute of Nanoscience, Delft University of Technology, 2628 Delft, The Netherlands
| | | | | | - Andrea Aguirre
- Centro de Física de Materiales CSIC/UPV-EHU-Materials Physics Center, 20018 Donostia-San Sebastián, Spain
| | | | - Dongfei Wang
- CIC nanoGUNE-BRTA, 20018 Donostia-San Sebastián, Spain
| | | | - Herre S J van der Zant
- Kavli Institute of Nanoscience, Delft University of Technology, 2628 Delft, The Netherlands
| | - Thomas Frederiksen
- Donostia International Physics Center (DIPC), 20018 Donostia-San Sebastián, Spain
- IKERBASQUE, Basque Foundation for Science, 48013 Bilbao, Spain
| | - Diego Peña
- Centro Singular de Investigación en Química Biolóxica e Materiais Moleculares (CiQUS) and Departamento de Química Orgánica, Universidade de Santiago de Compostela 15782 Santiago de Compostela, Spain
| | - Jose Ignacio Pascual
- CIC nanoGUNE-BRTA, 20018 Donostia-San Sebastián, Spain
- IKERBASQUE, Basque Foundation for Science, 48013 Bilbao, Spain
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2
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Jacobse PH, Sarker M, Saxena A, Zahl P, Wang Z, Berger E, Aluru NR, Sinitskii A, Crommie MF. Tunable Magnetic Coupling in Graphene Nanoribbon Quantum Dots. SMALL (WEINHEIM AN DER BERGSTRASSE, GERMANY) 2024; 20:e2400473. [PMID: 38412424 DOI: 10.1002/smll.202400473] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/20/2024] [Indexed: 02/29/2024]
Abstract
Carbon-based quantum dots (QDs) enable flexible manipulation of electronic behavior at the nanoscale, but controlling their magnetic properties requires atomically precise structural control. While magnetism is observed in organic molecules and graphene nanoribbons (GNRs), GNR precursors enabling bottom-up fabrication of QDs with various spin ground states have not yet been reported. Here the development of a new GNR precursor that results in magnetic QD structures embedded in semiconducting GNRs is reported. Inserting one such molecule into the GNR backbone and graphitizing it results in a QD region hosting one unpaired electron. QDs composed of two precursor molecules exhibit nonmagnetic, antiferromagnetic, or antiferromagnetic ground states, depending on the structural details that determine the coupling behavior of the spins originating from each molecule. The synthesis of these QDs and the emergence of localized states are demonstrated through high-resolution atomic force microscopy (HR-AFM), scanning tunneling microscopy (STM) imaging, and spectroscopy, and the relationship between QD atomic structure and magnetic properties is uncovered. GNR QDs provide a useful platform for controlling the spin-degree of freedom in carbon-based nanostructures.
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Affiliation(s)
- Peter H Jacobse
- Department of Physics, University of California, Berkeley, Berkeley, CA, 94720, USA
| | - Mamun Sarker
- Department of Chemistry, University of Nebraska, Lincoln, NE, 68588, USA
- Nebraska Center for Materials and Nanoscience, University of Nebraska-Lincoln, Lincoln, NE, 68588, USA
| | - Anshul Saxena
- Walker Department of Mechanical Engineering, University of Texas, Austin, TX, 78712, USA
- Oden Institute for Computational Engineering and Sciences, University of Texas at Austin, Austin, TX, 78712, USA
| | - Percy Zahl
- Center for Functional Nanomaterials, Brookhaven National Laboratory, Upton, NY, 11973, USA
| | - Ziyi Wang
- Department of Physics, University of California, Berkeley, Berkeley, CA, 94720, USA
- Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA
- Kavli Energy NanoSciences Institute at the University of California Berkeley and the Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA
| | - Emma Berger
- Department of Physics, University of California, Berkeley, Berkeley, CA, 94720, USA
| | - Narayana R Aluru
- Walker Department of Mechanical Engineering, University of Texas, Austin, TX, 78712, USA
- Oden Institute for Computational Engineering and Sciences, University of Texas at Austin, Austin, TX, 78712, USA
| | - Alexander Sinitskii
- Department of Chemistry, University of Nebraska, Lincoln, NE, 68588, USA
- Nebraska Center for Materials and Nanoscience, University of Nebraska-Lincoln, Lincoln, NE, 68588, USA
| | - Michael F Crommie
- Department of Physics, University of California, Berkeley, Berkeley, CA, 94720, USA
- Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA
- Kavli Energy NanoSciences Institute at the University of California Berkeley and the Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA
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3
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Song S, Pinar Solé A, Matěj A, Li G, Stetsovych O, Soler D, Yang H, Telychko M, Li J, Kumar M, Chen Q, Edalatmanesh S, Brabec J, Veis L, Wu J, Jelinek P, Lu J. Highly entangled polyradical nanographene with coexisting strong correlation and topological frustration. Nat Chem 2024; 16:938-944. [PMID: 38374456 DOI: 10.1038/s41557-024-01453-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2023] [Accepted: 01/17/2024] [Indexed: 02/21/2024]
Abstract
Open-shell nanographenes exhibit unconventional π-magnetism arising from topological frustration or strong electron-electron interaction. However, conventional design approaches are typically limited to a single magnetic origin, which can restrict the number of correlated spins or the type of magnetic ordering in open-shell nanographenes. Here we present a design strategy that combines topological frustration and electron-electron interactions to fabricate a large fully fused 'butterfly'-shaped tetraradical nanographene on Au(111). We employ bond-resolved scanning tunnelling microscopy and spin-excitation spectroscopy to resolve the molecular backbone and reveal the strongly correlated open-shell character, respectively. This nanographene contains four unpaired electrons with both ferromagnetic and anti-ferromagnetic interactions, harbouring a many-body singlet ground state and strong multi-spin entanglement, which is well described by many-body calculations. Furthermore, we study the magnetic properties and spin states in the nanographene using a nickelocene magnetic probe. The ability to imprint and characterize many-body strongly correlated spins in polyradical nanographenes paves the way for future advancements in quantum information technologies.
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Affiliation(s)
- Shaotang Song
- Department of Chemistry, National University of Singapore, Singapore, Singapore
| | - Andrés Pinar Solé
- Institute of Physics, Czech Academy of Sciences, Prague, Czech Republic
- Regional Centre of Advanced Technologies and Materials, Czech Advanced Technology and Research Institute, Palacký University Olomouc, Olomouc, Czech Republic
| | - Adam Matěj
- Institute of Physics, Czech Academy of Sciences, Prague, Czech Republic
- Regional Centre of Advanced Technologies and Materials, Czech Advanced Technology and Research Institute, Palacký University Olomouc, Olomouc, Czech Republic
| | - Guangwu Li
- Department of Chemistry, National University of Singapore, Singapore, Singapore
- Center of Single-Molecule Sciences, Frontiers Science Center for New Organic Matter, College of Electronic Information and Optical Engineering, Nankai University, Tianjin, China
| | | | - Diego Soler
- Institute of Physics, Czech Academy of Sciences, Prague, Czech Republic
| | - Huimin Yang
- Department of Chemistry, National University of Singapore, Singapore, Singapore
| | - Mykola Telychko
- Department of Chemistry, National University of Singapore, Singapore, Singapore
| | - Jing Li
- Department of Chemistry, National University of Singapore, Singapore, Singapore
| | - Manish Kumar
- Institute of Physics, Czech Academy of Sciences, Prague, Czech Republic
| | - Qifan Chen
- Institute of Physics, Czech Academy of Sciences, Prague, Czech Republic
| | | | - Jiri Brabec
- Department of Theoretical Chemistry, J. Heyrovsky Institute of Physical Chemistry, Czech Academy of Sciences, Prague, Czech Republic
| | - Libor Veis
- Department of Theoretical Chemistry, J. Heyrovsky Institute of Physical Chemistry, Czech Academy of Sciences, Prague, Czech Republic.
| | - Jishan Wu
- Department of Chemistry, National University of Singapore, Singapore, Singapore.
| | - Pavel Jelinek
- Institute of Physics, Czech Academy of Sciences, Prague, Czech Republic.
- Regional Centre of Advanced Technologies and Materials, Czech Advanced Technology and Research Institute, Palacký University Olomouc, Olomouc, Czech Republic.
| | - Jiong Lu
- Department of Chemistry, National University of Singapore, Singapore, Singapore.
- Institute for Functional Intelligent Materials, National University of Singapore, Singapore, Singapore.
- National University of Singapore (Suzhou) Research Institute, Suzhou, China.
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4
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Spalenza PEP, de Souza FAL, Amorim RG, Scheicher RH, Scopel WL. A high density nanopore 3-triangulene kagome lattice. NANOSCALE 2024; 16:9911-9916. [PMID: 38686534 DOI: 10.1039/d4nr00910j] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/02/2024]
Abstract
Nanopore-containing two-dimensional materials have been explored for a wide range of applications including filtration, sensing, catalysis, energy storage and conversion. Triangulenes have recently been experimentally synthesized in a variety of sizes. In this regard, using these systems as building blocks, we theoretically examined 3-triangulene kagome crystals with inherent holes of ∼12 Å diameter and a greater density array of nanopores (≥1013 cm-2) compared to conventional 2D systems. The energetic, electronic, and transport properties of pristine and B/N-doped 3-triangulene kagome crystals were evaluated through a combination of density functional theory and non-equilibrium Green's function method. The simulated scanning tunneling microscopy images clearly capture electronic perturbation around the doped sites, which can be used to distinguish the pristine system from the doped systems. The viability of precisely controlling the band structure and transport properties by changing the type and concentration of doping atoms is demonstrated. The findings presented herein can potentially widen the applicability of these systems that combine unique electronic properties and intrinsically high-density pores, which can pave the way for the next generation of nanopore-based devices.
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Affiliation(s)
| | | | - Rodrigo G Amorim
- Departamento de Física, ICEx, Universidade Federal Fluminense - UFF, Volta Redonda, RJ, Brazil.
| | - Ralph H Scheicher
- Division of Materials Theory, Department of Physics and Astronomy, Uppsala University, Box 516, SE-751 20 Uppsala, Sweden.
| | - Wanderlã Luis Scopel
- Departamento de Física, Universidade Federal do Espírito Santo - UFES, Vitória, ES, Brazil.
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5
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Xu S, Zhang Y, Zang C, Liu J, Jin W, Lefkidis G, Hübner W, Li C. Unlocking Ultrafast Spin Transfer in Single-Magnetic-Center-Decorated Triangulene Systems. J Phys Chem Lett 2024; 15:3929-3937. [PMID: 38568181 DOI: 10.1021/acs.jpclett.4c00469] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/12/2024]
Abstract
Triangulene, as a typical open-shell graphene fragment, has attracted widespread attention for nanospintronics, promising to serve as building blocks in spin-logic units. Here, using ab initio calculations, we systematically study the laser-induced ultrafast spin-dynamic processes on triangulene nanoflakes, decorated with a transition-metal atom. The results reveal a competition between the induced magnetic center and the carbon edge of the triangulene, resulting in the coexistence of dual spin-density-distribution patterns on such single-magnetic-center systems, thus opening up possibilities of complex spin-dynamic scenarios beyond the spin flip. Interestingly, no matter what direction the spin points to, it is possible to achieve reversible spin-transfer processes using the same laser pulse. Increasing the pool of elementary processes to contain not only spin-direction-dependent but also spin-direction-independent scenarios allows for more versatile spin-logic operations, including classical handling of information and quantum computing. In the present work, we suggest downscaling nanospintronic devices by integrating triangulene-based nanostructures.
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Affiliation(s)
- Shuai Xu
- Department of Engineering Mechanics, Northwestern Polytechnical University, Xi'an 710072, China
- Research & Development Institute of Northwestern Polytechnical University in Shenzhen, Shenzhen 518057, China
| | - Yiming Zhang
- Department of Engineering Mechanics, Northwestern Polytechnical University, Xi'an 710072, China
- School of Science, Xi'an University of Architecture and Technology, Xi'an 710055, China
| | - Congfei Zang
- Department of Engineering Mechanics, Northwestern Polytechnical University, Xi'an 710072, China
- Research & Development Institute of Northwestern Polytechnical University in Shenzhen, Shenzhen 518057, China
| | - Jing Liu
- Institute of Theoretical Chemistry, Ulm University, 89081 Ulm, Germany
| | - Wei Jin
- School of Physics and Information Technology, Shaanxi Normal University, Xi'an 710119, China
| | - Georgios Lefkidis
- Department of Engineering Mechanics, Northwestern Polytechnical University, Xi'an 710072, China
- Department of Physics, RPTU Kaiserslautern-Landau, P.O. Box 3049, 67653 Kaiserslautern, Germany
| | - Wolfgang Hübner
- Department of Physics, RPTU Kaiserslautern-Landau, P.O. Box 3049, 67653 Kaiserslautern, Germany
| | - Chun Li
- Department of Engineering Mechanics, Northwestern Polytechnical University, Xi'an 710072, China
- Research & Development Institute of Northwestern Polytechnical University in Shenzhen, Shenzhen 518057, China
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6
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Bernhardt A, Čavlović D, Mayländer M, Blacque O, Cruz CM, Richert S, Juríček M. π-Radical Cascade to a Chiral Saddle-Shaped Peropyrene. Angew Chem Int Ed Engl 2024; 63:e202318254. [PMID: 38278766 DOI: 10.1002/anie.202318254] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2023] [Revised: 01/12/2024] [Accepted: 01/25/2024] [Indexed: 01/28/2024]
Abstract
Reactions of open-shell molecular graphene fragments are typically thought of as undesired decomposition processes because they lead to the loss of desired features like π-magnetism. Oxidative dimerization of phenalenyl to peropyrene shows, however, that these transformations hold promise as a synthetic tool for making complex structures via formation of multiple bonds and rings in a single step. Here, we explore the feasibility of using this "undesired" reaction of phenalenyl to build up strain and provide access to non-planar polycyclic aromatic hydrocarbons. To this end, we designed and synthesized a biradical system with two phenalenyl units linked via a biphenylene backbone. The design facilitates an intramolecular cascade reaction to a helically twisted saddle-shaped product, where the key transformations-ring-closure and ring-fusion-occur within one reaction. The negative curvature of the final peropyrene product, induced by the formed eight-membered ring, was confirmed by single-crystal X-ray diffraction analysis and the helical twist was validated via resolution of the product's enantiomers that display circularly polarized luminescence and high configurational stability.
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Affiliation(s)
- Annika Bernhardt
- Department of Chemistry, University of Zurich, Winterthurerstrasse 190, 8057, Zurich, Switzerland
| | - Daniel Čavlović
- Department of Chemistry, University of Zurich, Winterthurerstrasse 190, 8057, Zurich, Switzerland
| | - Maximilian Mayländer
- Institute of Physical Chemistry, University of Freiburg, Albertstraße 21, 79104, Freiburg, Germany
| | - Olivier Blacque
- Department of Chemistry, University of Zurich, Winterthurerstrasse 190, 8057, Zurich, Switzerland
| | - Carlos M Cruz
- Department of Chemistry, University of Zurich, Winterthurerstrasse 190, 8057, Zurich, Switzerland
- Department of Organic Chemistry, University of Granada, Avenida de la Fuente Nueva S/N, 18071, Granada, Spain
| | - Sabine Richert
- Institute of Physical Chemistry, University of Freiburg, Albertstraße 21, 79104, Freiburg, Germany
| | - Michal Juríček
- Department of Chemistry, University of Zurich, Winterthurerstrasse 190, 8057, Zurich, Switzerland
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7
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Henriques J, Ferri-Cortés M, Fernández-Rossier J. Designer Spin Models in Tunable Two-Dimensional Nanographene Lattices. NANO LETTERS 2024; 24:3355-3360. [PMID: 38427975 PMCID: PMC10958603 DOI: 10.1021/acs.nanolett.3c04915] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/14/2023] [Revised: 02/26/2024] [Accepted: 02/27/2024] [Indexed: 03/03/2024]
Abstract
Motivated by recent experimental breakthroughs, we propose a strategy for designing two-dimensional spin-lattices with competing interactions that lead to nontrivial emergent quantum states. We consider S = 1/2 nanographenes with C3 symmetry as building blocks, and we leverage the potential to control both the sign and the strength of exchange with first neighbors to build a family of spin models. Specifically, we consider the case of a Heisenberg model in a triangle-decorated honeycomb lattice with competing ferromagnetic and antiferromagnetic interactions whose ratio can be varied in a wide range. On the basis of the exact diagonalization of both Fermionic and spin models, we predict a quantum phase transition between a valence bond crystal of spin singlets with triplon excitations living in a Kagomé lattice and a Néel phase of effective S = 3/2 in the limit of dominant ferromagnetic interactions.
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Affiliation(s)
- João Henriques
- International
Iberian Nanotechnology Laboratory (INL), Av. Mestre José Veiga, 4715-330 Braga, Portugal
- Universidade
de Santiago de Compostela, 15782 Santiago de Compostela, Spain
| | - Mar Ferri-Cortés
- Departamento
de Física Aplicada, Universidad de
Alicante, 03690 San Vicente del Raspeig, Spain
| | - Joaquín Fernández-Rossier
- International
Iberian Nanotechnology Laboratory (INL), Av. Mestre José Veiga, 4715-330 Braga, Portugal
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8
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Zhu X, Li K, Liu J, Wang Z, Ding Z, Su Y, Yang B, Yan K, Li G, Yu P. Topological Structure Realized in Cove-Edged Graphene Nanoribbons via Incorporation of Periodic Pentagon Rings. J Am Chem Soc 2024; 146:7152-7158. [PMID: 38421279 DOI: 10.1021/jacs.4c00270] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/02/2024]
Abstract
Cove-edged zigzag graphene nanoribbons are predicted to show metallic, topological, or trivial semiconducting band structures, which are precisely determined by their cove offset positions at both edges as well as the ribbon width. However, due to the challenge of introducing coves into zigzag-edged graphene nanoribbons, only a few cove-edged graphene nanoribbons with trivial semiconducting bandgaps have been realized experimentally. Here, we report that the topological band structure can be realized in cove-edged graphene nanoribbons by embedding periodic pentagon rings on the cove edges through on-surface synthesis. Upon noncontact atomic force microscopy and scanning tunneling spectroscopy measurements, the chemical and electronic structures of cove-edged graphene nanoribbons with periodic pentagon rings have been characterized for different lengths. Combined with theoretical calculations, we find that upon inducing periodic pentagon rings the cove-edged graphene nanoribbons exhibit nontrivial topological structures. Our results provide insights for the design and understanding of the topological character in cove-edged graphene nanoribbons.
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Affiliation(s)
- Xujie Zhu
- School of Physical Science and Technology, ShanghaiTech University, 201210 Shanghai, China
| | - Kezhen Li
- School of Physical Science and Technology, ShanghaiTech University, 201210 Shanghai, China
| | - Jian Liu
- School of Physical Science and Technology, ShanghaiTech University, 201210 Shanghai, China
| | - Zhou Wang
- School of Physical Science and Technology, ShanghaiTech University, 201210 Shanghai, China
| | - Zhihao Ding
- School of Physical Science and Technology, ShanghaiTech University, 201210 Shanghai, China
| | - Yunlong Su
- School of Physical Science and Technology, ShanghaiTech University, 201210 Shanghai, China
| | - Bo Yang
- School of Physical Science and Technology, ShanghaiTech University, 201210 Shanghai, China
| | - KaKing Yan
- School of Physical Science and Technology, ShanghaiTech University, 201210 Shanghai, China
| | - Gang Li
- School of Physical Science and Technology, ShanghaiTech University, 201210 Shanghai, China
- ShanghaiTech Laboratory for Topological Physics, ShanghaiTech University, 201210 Shanghai, China
| | - Ping Yu
- School of Physical Science and Technology, ShanghaiTech University, 201210 Shanghai, China
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9
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Fang T, Zhang T, Hu T, Wang Z. Atomic-Limit Mott Insulator in [4]Triangulene Frameworks. NANO LETTERS 2024; 24:3059-3066. [PMID: 38426713 DOI: 10.1021/acs.nanolett.3c04675] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 03/02/2024]
Abstract
Triangulene, one unique class of zigzag-edged triangular graphene molecules, has attracted tremendous research interest. In this work, as an ultimate phase of the Mott insulator, we present the realization of the atomic-limit Mott insulator in experimentally synthesized [4]triangulene frameworks ([4]-TGFs) from first-principles calculations. The frontier molecular orbitals of the nonmagnetic [4]triangulene consist of three coupled corner modes. After the isolated [4]triangulene is assembled into [4]-TGF, one special enantiomorphic flat band is created through the coupling of these corner modes, which is identified to be a second-order topological insulator with half-filled topological corner states at the Fermi level. Moreover, [4]-TGF prefers an antiferromagnetic ground state under Hubbard interactions, which further splits these metallic zero-energy states into an atomic-limit Mott insulator with spin-polarized corners. Since the fractional filling of topological corner states is a smoking-gun signature of higher-order topology, our results demonstrate a universal approach to explore the atomic-limit Mott insulators in higher-order topological materials.
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Affiliation(s)
- Tiancheng Fang
- Hefei National Research Center for Physical Sciences at the Microscale, CAS Key Laboratory of Strongly-Coupled Quantum Matter Physics, Department of Physics, University of Science and Technology of China, Hefei, Anhui 230026, People's Republic of China
| | - Tingfeng Zhang
- Hefei National Research Center for Physical Sciences at the Microscale, CAS Key Laboratory of Strongly-Coupled Quantum Matter Physics, Department of Physics, University of Science and Technology of China, Hefei, Anhui 230026, People's Republic of China
| | - Tianyi Hu
- Hefei National Research Center for Physical Sciences at the Microscale, CAS Key Laboratory of Strongly-Coupled Quantum Matter Physics, Department of Physics, University of Science and Technology of China, Hefei, Anhui 230026, People's Republic of China
| | - Zhengfei Wang
- Hefei National Research Center for Physical Sciences at the Microscale, CAS Key Laboratory of Strongly-Coupled Quantum Matter Physics, Department of Physics, University of Science and Technology of China, Hefei, Anhui 230026, People's Republic of China
- Hefei National Laboratory, University of Science and Technology of China, Hefei, Anhui 230088, People's Republic of China
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10
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Zhao C, Huang Q, Valenta L, Eimre K, Yang L, Yakutovich AV, Xu W, Ma J, Feng X, Juríček M, Fasel R, Ruffieux P, Pignedoli CA. Tailoring Magnetism of Graphene Nanoflakes via Tip-Controlled Dehydrogenation. PHYSICAL REVIEW LETTERS 2024; 132:046201. [PMID: 38335341 DOI: 10.1103/physrevlett.132.046201] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/22/2023] [Revised: 11/14/2023] [Accepted: 12/15/2023] [Indexed: 02/12/2024]
Abstract
Atomically precise graphene nanoflakes called nanographenes have emerged as a promising platform to realize carbon magnetism. Their ground state spin configuration can be anticipated by Ovchinnikov-Lieb rules based on the mismatch of π electrons from two sublattices. While rational geometrical design achieves specific spin configurations, further direct control over the π electrons offers a desirable extension for efficient spin manipulations and potential quantum device operations. To this end, we apply a site-specific dehydrogenation using a scanning tunneling microscope tip to nanographenes deposited on a Au(111) substrate, which shows the capability of precisely tailoring the underlying π-electron system and therefore efficiently manipulating their magnetism. Through first-principles calculations and tight-binding mean-field-Hubbard modeling, we demonstrate that the dehydrogenation-induced Au-C bond formation along with the resulting hybridization between frontier π orbitals and Au substrate states effectively eliminate the unpaired π electron. Our results establish an efficient technique for controlling the magnetism of nanographenes.
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Affiliation(s)
- Chenxiao Zhao
- Empa-Swiss Federal Laboratories for Materials Science and Technology, Dübendorf 8600, Switzerland
| | - Qiang Huang
- Faculty of Chemistry and Food Chemistry, and Center for Advancing Electronics Dresden, Technical University of Dresden, Dresden 01062, Germany
| | - Leoš Valenta
- Department of Chemistry, University of Zurich, Zurich 8057, Switzerland
| | - Kristjan Eimre
- Empa-Swiss Federal Laboratories for Materials Science and Technology, Dübendorf 8600, Switzerland
| | - Lin Yang
- Faculty of Chemistry and Food Chemistry, and Center for Advancing Electronics Dresden, Technical University of Dresden, Dresden 01062, Germany
| | - Aliaksandr V Yakutovich
- Empa-Swiss Federal Laboratories for Materials Science and Technology, Dübendorf 8600, Switzerland
| | - Wangwei Xu
- Empa-Swiss Federal Laboratories for Materials Science and Technology, Dübendorf 8600, Switzerland
- Department of Chemistry, Biochemistry and Pharmaceutical Sciences, University of Bern, Bern 3012, Switzerland
| | - Ji Ma
- Faculty of Chemistry and Food Chemistry, and Center for Advancing Electronics Dresden, Technical University of Dresden, Dresden 01062, Germany
- Max Planck Institute of Microstructure Physics, Weinberg 2, Halle 06120, Germany
| | - Xinliang Feng
- Faculty of Chemistry and Food Chemistry, and Center for Advancing Electronics Dresden, Technical University of Dresden, Dresden 01062, Germany
- Max Planck Institute of Microstructure Physics, Weinberg 2, Halle 06120, Germany
| | - Michal Juríček
- Department of Chemistry, University of Zurich, Zurich 8057, Switzerland
| | - Roman Fasel
- Empa-Swiss Federal Laboratories for Materials Science and Technology, Dübendorf 8600, Switzerland
- Department of Chemistry, Biochemistry and Pharmaceutical Sciences, University of Bern, Bern 3012, Switzerland
| | - Pascal Ruffieux
- Empa-Swiss Federal Laboratories for Materials Science and Technology, Dübendorf 8600, Switzerland
| | - Carlo A Pignedoli
- Empa-Swiss Federal Laboratories for Materials Science and Technology, Dübendorf 8600, Switzerland
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11
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Sakr MAS, Saad MA, Abd-Elkader OH, Abdelsalam H, Zhang Q. Promising sensors for pharmaceutical pollutant adsorption using Clar's goblet-based 2D membranes. Sci Rep 2024; 14:889. [PMID: 38195577 PMCID: PMC10776697 DOI: 10.1038/s41598-023-50802-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2023] [Accepted: 12/26/2023] [Indexed: 01/11/2024] Open
Abstract
This study focuses on the design of new 2D membranes from connected Clar's Goblet as a potential sensor for pharmaceutical pollutants, specifically the painkiller drugs aspirin, paracetamol, ibuprofen, and diclofenac. The electronic, optical, and interaction properties are investigated using density functional theory calculations. The Clar's Goblet membranes (CGMs) that were chosen are semiconductors with an energy gap of around 1.5 eV, according to energy gap calculations and density of states. Molecular electrostatic potential (ESP) analysis shows that CGMs have electrophilic and nucleophilic sites, suggesting their suitability for interacting with pharmaceutical pollutants. The adsorption energies confirm the chemical adsorption of pharmaceutical pollutants with diclofenac showing the strongest adsorption. The UV-Vis absorption spectra of CGMs-drug complexes are analyzed, revealing a redshift compared to the absorption spectrum of CGMs alone, confirming the adsorption of these drugs. Further analysis using hole/electron examinations indicates that the type of excitation is local excitation rather than charge transfer excitation. This study quantitatively characterized hole and electron distribution in excited states using various indices. The analysis revealed local excitation transitions and significant charge transfer between the CGMs molecule and pharmaceutical pollutants. Additionally, non-covalent interaction analysis indicates the presence of van der Waals interactions, highlighting the adsorption behavior of the drugs. These results demonstrate the potential of CGMs as a highly sensitive sensor for pharmaceutical pollutants.
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Affiliation(s)
- Mahmoud A S Sakr
- Chemistry Department, Center of Basic Science (CBS), Misr University of Science and Technology (MUST), 6th October City, Egypt.
| | - Mohamed A Saad
- Physics Department, Center of Basic Science (CBS), Misr University of Science and Technology (MUST), 6th October City, Egypt
| | - Omar H Abd-Elkader
- Department of Physics and Astronomy, College of Science, King Saud University, P.O. Box 2455, 11451, Riyadh, Saudi Arabia
| | - Hazem Abdelsalam
- Theoretical Physics Department, National Research Centre, El-Buhouth Str., Dokki, Giza, 12622, Egypt.
- School of Materials Science and Engineering, Yancheng Institute of Technology, Yancheng, 224051, People's Republic of China.
| | - Qinfang Zhang
- School of Materials Science and Engineering, Yancheng Institute of Technology, Yancheng, 224051, People's Republic of China.
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12
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Calupitan JP, Berdonces-Layunta A, Aguilar-Galindo F, Vilas-Varela M, Peña D, Casanova D, Corso M, de Oteyza DG, Wang T. Emergence of π-Magnetism in Fused Aza-Triangulenes: Symmetry and Charge Transfer Effects. NANO LETTERS 2023; 23:9832-9840. [PMID: 37870305 PMCID: PMC10722538 DOI: 10.1021/acs.nanolett.3c02586] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/11/2023] [Revised: 10/16/2023] [Accepted: 10/17/2023] [Indexed: 10/24/2023]
Abstract
On-surface synthesis has paved the way toward the fabrication and characterization of conjugated carbon-based molecular materials that exhibit π-magnetism such as triangulenes. Aza-triangulene, a nitrogen-substituted derivative, was recently shown to display rich on-surface chemistry, offering an ideal platform to investigate structure-property relations regarding spin-selective charge transfer and magnetic fingerprints. Herein, we study electronic changes upon fusion of single molecules into larger dimeric derivatives. We show that the closed-shell structure of aza-triangulene on Ag(111) leads to closed-shell dimers covalently coupled through sterically accessible carbon atoms. Meanwhile, its open-shell structure on Au(111) leads to coupling via atoms displaying a high spin density, resulting in symmetric or asymmetric products. Interestingly, whereas all dimers on Au(111) exhibit similar charge transfer properties, only asymmetric ones show magnetic fingerprints due to spin-selective charge transfer. These results expose clear relationships among molecular symmetry, charge transfer, and spin states of π-conjugated carbon-based nanostructures.
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Affiliation(s)
- Jan Patrick Calupitan
- Centro
de Física de Materiales (CFM-MPC), CSIC-UPV/EHU, 20018 San Sebastián, Spain
- Donostia
International Physics Center, 20018 San Sebastián, Spain
| | - Alejandro Berdonces-Layunta
- Centro
de Física de Materiales (CFM-MPC), CSIC-UPV/EHU, 20018 San Sebastián, Spain
- Donostia
International Physics Center, 20018 San Sebastián, Spain
| | - Fernando Aguilar-Galindo
- Departamento
de Química, Universidad Autónoma
de Madrid, 28049 Madrid, Spain
- Institute
for Advanced Research in Chemical Sciences (IAdChem), Universidad Autónoma de Madrid, 28049 Madrid, Spain
| | - Manuel Vilas-Varela
- Centro
Singular de Investigación en Química Biolóxica
e Materiais Moleculares (CiQUS) and Departamento de Química
Orgánica, Universidade de Santiago
de Compostela, 15782 Santiago de Compostela, Spain
| | - Diego Peña
- Centro
Singular de Investigación en Química Biolóxica
e Materiais Moleculares (CiQUS) and Departamento de Química
Orgánica, Universidade de Santiago
de Compostela, 15782 Santiago de Compostela, Spain
| | - David Casanova
- Donostia
International Physics Center, 20018 San Sebastián, Spain
- Ikerbasque, Basque Foundation
for Science, 48009 Bilbao, Spain
| | - Martina Corso
- Centro
de Física de Materiales (CFM-MPC), CSIC-UPV/EHU, 20018 San Sebastián, Spain
- Donostia
International Physics Center, 20018 San Sebastián, Spain
| | - Dimas G. de Oteyza
- Centro
de Física de Materiales (CFM-MPC), CSIC-UPV/EHU, 20018 San Sebastián, Spain
- Donostia
International Physics Center, 20018 San Sebastián, Spain
- Nanomaterials
and Nanotechnology Research Center (CINN), CSIC-UNIOVI-PA, 33940 El Entrego, Spain
| | - Tao Wang
- Centro
de Física de Materiales (CFM-MPC), CSIC-UPV/EHU, 20018 San Sebastián, Spain
- Donostia
International Physics Center, 20018 San Sebastián, Spain
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13
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Krane N, Turco E, Bernhardt A, Jacob D, Gandus G, Passerone D, Luisier M, Juríček M, Fasel R, Fernández-Rossier J, Ruffieux P. Exchange Interactions and Intermolecular Hybridization in a Spin- 1/ 2 Nanographene Dimer. NANO LETTERS 2023; 23:9353-9359. [PMID: 37819646 DOI: 10.1021/acs.nanolett.3c02633] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/13/2023]
Abstract
Phenalenyl is a radical nanographene with a triangular shape hosting an unpaired electron with spin S = 1/2. The open-shell nature of the phenalenyl is expected to be retained in covalently bonded networks. As a first step, we report synthesis of the phenalenyl dimer by combining in-solution synthesis and on-surface activation and its characterization on Au(111) and on a NaCl decoupling layer by means of inelastic electron tunneling spectroscopy (IETS). IETS shows inelastic steps that are identified as singlet-triplet excitation arising from interphenalenyl exchange. Spin excitation energies with and without the NaCl decoupling layer are 48 and 41 meV, respectively, indicating significant renormalization due to exchange with Au(111) electrons. Furthermore, third-neighbor hopping-induced interphenalenyl hybridization is fundamental to explaining the position-dependent bias asymmetry of the inelastic steps and activation of kinetic interphenalenyl exchange. Our results pave the way for bottom-up synthesis of S = 1/2 spin-lattices with large exchange interactions.
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Affiliation(s)
- N Krane
- nanotech@surfaces Laboratory, Empa - Swiss Federal Laboratories for Materials Science and Technology, Ueberlandstrasse 129, 8600 Dübendorf, Switzerland
| | - E Turco
- nanotech@surfaces Laboratory, Empa - Swiss Federal Laboratories for Materials Science and Technology, Ueberlandstrasse 129, 8600 Dübendorf, Switzerland
| | - A Bernhardt
- Department of Chemistry, University of Zurich, Winterthurerstrasse 190, 8057 Zurich, Switzerland
| | - D Jacob
- Departamento de Polímeros y Materiales Avanzados: Física, Química y Tecnología, Universidad del País Vasco UPV/EHU, Av. Tolosa 72, E-20018 San Sebastián, Spain
- Basque Foundation for Science, IKERBASQUE, Plaza Euskadi 5, E-48009 Bilbao, Spain
| | - G Gandus
- Integrated Systems Laboratory, ETH Zürich, Gloriastrasse 35, 8092 Zürich, Switzerland
| | - D Passerone
- nanotech@surfaces Laboratory, Empa - Swiss Federal Laboratories for Materials Science and Technology, Ueberlandstrasse 129, 8600 Dübendorf, Switzerland
| | - M Luisier
- Integrated Systems Laboratory, ETH Zürich, Gloriastrasse 35, 8092 Zürich, Switzerland
| | - M Juríček
- Department of Chemistry, University of Zurich, Winterthurerstrasse 190, 8057 Zurich, Switzerland
| | - R Fasel
- nanotech@surfaces Laboratory, Empa - Swiss Federal Laboratories for Materials Science and Technology, Ueberlandstrasse 129, 8600 Dübendorf, Switzerland
- Department of Chemistry, Biochemistry and Pharmaceutical Sciences, University of Bern, Freiestrasse 3, 3012 Bern, Switzerland
| | - J Fernández-Rossier
- International Iberian Nanotechnology Laboratory (INL), Avenida Mestre José Veiga s/n, 4715-330 Braga, Portugal
| | - P Ruffieux
- nanotech@surfaces Laboratory, Empa - Swiss Federal Laboratories for Materials Science and Technology, Ueberlandstrasse 129, 8600 Dübendorf, Switzerland
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14
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Lawrence J, He Y, Wei H, Su J, Song S, Wania Rodrigues A, Miravet D, Hawrylak P, Zhao J, Wu J, Lu J. Topological Design and Synthesis of High-Spin Aza-triangulenes without Jahn-Teller Distortions. ACS NANO 2023; 17:20237-20245. [PMID: 37791737 DOI: 10.1021/acsnano.3c05974] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/05/2023]
Abstract
The atomic doping of open-shell nanographenes enables precise tuning of their electronic and magnetic states, which is crucial for their promising potential applications in optoelectronics and spintronics. Among this intriguing class of molecules, triangulenes stand out with their size-dependent electronic properties and spin states, which can also be influenced by the presence of dopant atoms and functional groups. However, the occurrence of Jahn-Teller distortions in such systems can have a crucial impact on their total spin and requires further theoretical and experimental investigation. In this study, we examine the nitrogen-doped aza-triangulene series via a combination of density functional theory and on-surface synthesis. We identify a general trend in the calculated spin states of aza-[n]triangulenes of various sizes, separating them into two symmetry classes, one of which features molecules that are predicted to undergo Jahn-Teller distortions that reduce their symmetry and thus their total spin. We link this behavior to the location of the central nitrogen atom relative to the two underlying carbon sublattices of the molecules. Consequently, our findings reveal that neutral centrally doped aza-triangulenes have one less radical than their undoped counterparts, irrespective of their predicted symmetry. We follow this by demonstrating the on-surface synthesis of π-extended aza-[5]triangulene, a large member of the higher symmetry class without Jahn-Teller distortions, via a simple one-step annealing process on Cu(111) and Au(111). Using scanning probe microscopy and spectroscopy combined with theoretical calculations, we prove that the molecule is positively charged on the Au(111) substrate, with a high-spin quintet state of S = 2, the same total spin as undoped neutral [5]triangulene. Our study uncovers the correlation between the dopant position and the radical nature of high-spin nanographenes, providing a strategy for the design and development of these nanographenes for various applications.
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Affiliation(s)
- James Lawrence
- Department of Chemistry, National University of Singapore, 117543 Singapore
| | - Yuanyuan He
- College of Material and Textile Engineering, Key Laboratory of Yarn Materials Forming and Composite Processing Technology of Zhejiang Province, Jiaxing University, Jiaxing 314001, Zhejiang, People's Republic of China
| | - Haipeng Wei
- Department of Chemistry, National University of Singapore, 117543 Singapore
| | - Jie Su
- Department of Chemistry, National University of Singapore, 117543 Singapore
| | - Shaotang Song
- Department of Chemistry, National University of Singapore, 117543 Singapore
| | | | - Daniel Miravet
- Department of Physics, University of Ottawa, Ottawa, Ontario K1N 6N5, Canada
| | - Pawel Hawrylak
- Department of Physics, University of Ottawa, Ottawa, Ontario K1N 6N5, Canada
- Institute for Functional Intelligent Materials, National University of Singapore, 117544 Singapore
| | - Jianwei Zhao
- College of Material and Textile Engineering, Key Laboratory of Yarn Materials Forming and Composite Processing Technology of Zhejiang Province, Jiaxing University, Jiaxing 314001, Zhejiang, People's Republic of China
| | - Jishan Wu
- Department of Chemistry, National University of Singapore, 117543 Singapore
| | - Jiong Lu
- Department of Chemistry, National University of Singapore, 117543 Singapore
- Institute for Functional Intelligent Materials, National University of Singapore, 117544 Singapore
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15
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Vilas-Varela M, Romero-Lara F, Vegliante A, Calupitan JP, Martínez A, Meyer L, Uriarte-Amiano U, Friedrich N, Wang D, Schulz F, Koval NE, Sandoval-Salinas ME, Casanova D, Corso M, Artacho E, Peña D, Pascual JI. On-Surface Synthesis and Characterization of a High-Spin Aza-[5]-Triangulene. Angew Chem Int Ed Engl 2023; 62:e202307884. [PMID: 37604782 DOI: 10.1002/anie.202307884] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2023] [Revised: 08/11/2023] [Accepted: 08/17/2023] [Indexed: 08/23/2023]
Abstract
Triangulenes are a class of open-shell triangular graphene flakes with total spin increasing with their size. In the last years, on-surface-synthesis strategies have permitted fabricating and engineering triangulenes of various sizes and structures with atomic precision. However, direct proof of the increasing total spin with their size remains elusive. In this work, we report the combined in-solution and on-surface synthesis of a large nitrogen-doped triangulene (aza-[5]-triangulene) on a Au(111) surface, and the detection of its high-spin ground state. Bond-resolved scanning tunneling microscopy images uncovered radical states distributed along the zigzag edges, which were detected as weak zero-bias resonances in scanning tunneling spectra. These spectral features reveal the partial Kondo screening of a high-spin state. Through a combination of several simulation tools, we find that the observed distribution of radical states is explained by a quintet ground state (S=2), instead of the quartet state (S=3/2) expected for the neutral species. This confirms that electron transfer to the metal substrate raises the spin of the ground state. We further provide a qualitative description of the change of (anti)aromaticity introduced by N-substitution, and its role in the charge stabilization on a surface, resulting in an S=2 aza-triangulene on Au(111).
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Affiliation(s)
- Manuel Vilas-Varela
- Centro Singular de Investigación en Química Biolóxica e Materiais Moleculares (CiQUS) and Departamento de Química Orgánica, Universidade de Santiago de Compostela, 15782-, Santiago de Compostela, Spain
| | | | | | - Jan Patrick Calupitan
- Centro de Física de Materiales CSIC/UPV-EHU-Materials Physics Center, 20018, Donostia-San Sebastián, Spain
- Donostia International Physics Center (DIPC), 20018, Donostia-San Sebastián, Spain
| | - Adrián Martínez
- Centro Singular de Investigación en Química Biolóxica e Materiais Moleculares (CiQUS) and Departamento de Química Orgánica, Universidade de Santiago de Compostela, 15782-, Santiago de Compostela, Spain
| | - Lorenz Meyer
- CIC nanoGUNE-BRTA, 20018, Donostia-San Sebastián, Spain
| | | | | | - Dongfei Wang
- CIC nanoGUNE-BRTA, 20018, Donostia-San Sebastián, Spain
| | - Fabian Schulz
- CIC nanoGUNE-BRTA, 20018, Donostia-San Sebastián, Spain
| | | | | | - David Casanova
- Donostia International Physics Center (DIPC), 20018, Donostia-San Sebastián, Spain
- Ikerbasque, Basque Foundation for Science, 48009, Bilbao, Spain
| | - Martina Corso
- Centro de Física de Materiales CSIC/UPV-EHU-Materials Physics Center, 20018, Donostia-San Sebastián, Spain
| | - Emilio Artacho
- CIC nanoGUNE-BRTA, 20018, Donostia-San Sebastián, Spain
- Ikerbasque, Basque Foundation for Science, 48009, Bilbao, Spain
- Theory of Condensed Matter, Cavendish Laboratory, University of Cambridge, J. J. Thomson Ave., Cambridge, CB3 0HE, UK
| | - Diego Peña
- Centro Singular de Investigación en Química Biolóxica e Materiais Moleculares (CiQUS) and Departamento de Química Orgánica, Universidade de Santiago de Compostela, 15782-, Santiago de Compostela, Spain
| | - José Ignacio Pascual
- CIC nanoGUNE-BRTA, 20018, Donostia-San Sebastián, Spain
- Ikerbasque, Basque Foundation for Science, 48009, Bilbao, Spain
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16
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Wu F, Barragán A, Gallardo A, Yang L, Biswas K, Écija D, Mendieta-Moreno JI, Urgel JI, Ma J, Feng X. Structural Expansion of Cyclohepta[def]fluorene towards Azulene-Embedded Non-Benzenoid Nanographenes. Chemistry 2023; 29:e202301739. [PMID: 37339368 DOI: 10.1002/chem.202301739] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2023] [Revised: 06/20/2023] [Accepted: 06/20/2023] [Indexed: 06/22/2023]
Abstract
Non-benzenoid non-alternant nanographenes (NGs) have attracted increasing attention on account of their distinct electronic and structural features in comparison to their isomeric benzenoid counterparts. In this work, we present a series of unprecedented azulene-embedded NGs on Au(111) during the attempted synthesis of cyclohepta[def]fluorene-based high-spin non-Kekulé structure. Comprehensive scanning tunneling microscopy (STM) and non-contact atomic force microscopy (nc-AFM) evidence the structures and conformations of these unexpected products. The dynamics of the precursor bearing 9-(2,6-dimethylphenyl)anthracene and dihydro-dibenzo-cyclohepta[def]fluorene units and its reaction products on the surface are analyzed by density functional theory (DFT) and molecular dynamics (MD) simulations. Our study sheds light on the fundamental understanding of precursor design for the fabrication of π-extended non-benzenoid NGs on a metal surface.
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Affiliation(s)
- Fupeng Wu
- Max Planck Institute of Microstructure Physics, Weinberg 2, 06120, Halle, Germany
- Center for Advancing Electronics Dresden (cfaed) &, Faculty of Chemistry and Food Chemistry, Technische Universität Dresden, Mommsenstrasse 4, 01062, Dresden, Germany
| | - Ana Barragán
- IMDEA Nanoscience, C/Faraday 9, Campus de Cantoblanco, 28049, Madrid, Spain
| | - Aurelio Gallardo
- IMDEA Nanoscience, C/Faraday 9, Campus de Cantoblanco, 28049, Madrid, Spain
| | - Lin Yang
- Center for Advancing Electronics Dresden (cfaed) &, Faculty of Chemistry and Food Chemistry, Technische Universität Dresden, Mommsenstrasse 4, 01062, Dresden, Germany
| | - Kalyan Biswas
- IMDEA Nanoscience, C/Faraday 9, Campus de Cantoblanco, 28049, Madrid, Spain
| | - David Écija
- IMDEA Nanoscience, C/Faraday 9, Campus de Cantoblanco, 28049, Madrid, Spain
| | - Jesús I Mendieta-Moreno
- Departamento de Física Teórica de la Materia Condensada, Universidad Autónoma de Madrid, 28049, Madrid, Spain
| | - José I Urgel
- IMDEA Nanoscience, C/Faraday 9, Campus de Cantoblanco, 28049, Madrid, Spain
| | - Ji Ma
- Max Planck Institute of Microstructure Physics, Weinberg 2, 06120, Halle, Germany
- Center for Advancing Electronics Dresden (cfaed) &, Faculty of Chemistry and Food Chemistry, Technische Universität Dresden, Mommsenstrasse 4, 01062, Dresden, Germany
| | - Xinliang Feng
- Max Planck Institute of Microstructure Physics, Weinberg 2, 06120, Halle, Germany
- Center for Advancing Electronics Dresden (cfaed) &, Faculty of Chemistry and Food Chemistry, Technische Universität Dresden, Mommsenstrasse 4, 01062, Dresden, Germany
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17
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Yu H, Heine T. Magnetic Coupling Control in Triangulene Dimers. J Am Chem Soc 2023; 145:19303-19311. [PMID: 37610306 PMCID: PMC10485925 DOI: 10.1021/jacs.3c05178] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2023] [Indexed: 08/24/2023]
Abstract
Metal-free magnetism remains an enigmatic field, offering prospects for unconventional magnetic and electronic devices. In the pursuit of such magnetism, triangulenes, endowed with inherent spin polarization, are promising candidates to serve as monomers to construct extended structures. However, controlling and enhancing the magnetic interactions between the monomers persist as a significant challenge in molecular spintronics, as so far only weak antiferromagnetic coupling through the linkage has been realized, hindering their room temperature utilization. Herein, we investigate 24 triangulene dimers using first-principles calculations and demonstrate their tunable magnetic coupling (J), achieving unprecedented strong J values of up to -144 meV in a non-Kekulé dimer. We further establish a positive correlation between bandgap, electronic coupling, and antiferromagnetic interaction, thereby providing molecular-level insights into enhancing magnetic interactions. By twisting the molecular fragments, we demonstrate an effective and feasible approach to control both the sign and strength of J by tuning the balance between potential and kinetic exchanges. We discover that J can be substantially boosted at planar configurations up to -198 meV. We realize ferromagnetic coupling in nitrogen-doped triangulene dimers at both planar and largely twisted configurations, representing the first example of ferromagnetic triangulene dimers that cannot be predicted by the Ovchinnikov rule. This work thus provides a practical strategy for augmenting magnetic coupling and open up new avenues for metal-free ferromagnetism.
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Affiliation(s)
- Hongde Yu
- Faculty
of Chemistry and Food Chemistry, Technische
Universität Dresden, Bergstraße 66c, 01062 Dresden, Germany
| | - Thomas Heine
- Faculty
of Chemistry and Food Chemistry, Technische
Universität Dresden, Bergstraße 66c, 01062 Dresden, Germany
- Institute
of Resource Ecology, Helmholtz Zentrum Dresden-Rossendorf, Permoserstraße 15, 04318 Leipzig, Germany
- Department
of Chemistry, Yonsei University, Seodaemun-gu, Seoul 120-749, Republic of Korea
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18
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Abdelsalam H, Abd-Elkader OH, Sakr MAS, Saroka VA, Zhang Q. Nanoporous Triangulene-Based Frameworks for the Separation of Petroleum Hydrocarbons: Electronic, Magnetic, Optical, and Adsorption Properties. ACS APPLIED NANO MATERIALS 2023; 6:15128-15137. [DOI: 10.1021/acsanm.3c02689] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 09/02/2023]
Affiliation(s)
- Hazem Abdelsalam
- School of Materials Science and Engineering, Yancheng Institute of Technology, Yancheng 224051, P. R. China
- Theoretical Physics Department, National Research Centre, El-Buhouth Strasse, Giza 12622, Dokki, Egypt
| | - Omar H. Abd-Elkader
- Department of Physics and Astronomy, College of Science, King Saud University, P.O. Box 2455, Riyadh 11451, Saudi Arabia
| | - Mahmoud A. S. Sakr
- Center of Basic Science, Misr University for Science and Technology, 6th October City, Giza, Governorate 3236101, Egypt
| | - Vasil A. Saroka
- Department of Physics, University of Rome Tor Vergata and Istituto Nazionale di Fisica Nucleare, Via della Ricerca Scientifica 1, Rome 00133, Italy
- Institute for Nuclear Problems, Belarusian State University, Bobruiskaya 11, Minsk 220030, Belarus
- TBpack Ltd., 27 Old Gloucester Street, London WC1N 3AX, U.K
| | - Qinfang Zhang
- School of Materials Science and Engineering, Yancheng Institute of Technology, Yancheng 224051, P. R. China
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19
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Du Q, Su X, Liu Y, Jiang Y, Li C, Yan K, Ortiz R, Frederiksen T, Wang S, Yu P. Orbital-symmetry effects on magnetic exchange in open-shell nanographenes. Nat Commun 2023; 14:4802. [PMID: 37558678 PMCID: PMC10412602 DOI: 10.1038/s41467-023-40542-0] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2022] [Accepted: 08/01/2023] [Indexed: 08/11/2023] Open
Abstract
Open-shell nanographenes appear as promising candidates for future applications in spintronics and quantum technologies. A critical aspect to realize this potential is to design and control the magnetic exchange. Here, we reveal the effects of frontier orbital symmetries on the magnetic coupling in diradical nanographenes through scanning probe microscope measurements and different levels of theoretical calculations. In these open-shell nanographenes, the exchange energy exhibits a remarkable variation between 20 and 160 meV. Theoretical calculations reveal that frontier orbital symmetries play a key role in affecting the magnetic coupling on such a large scale. Moreover, a triradical nanographene is demonstrated for investigating the magnetic interaction among three unpaired electrons with unequal magnetic exchange, in agreement with Heisenberg spin model calculations. Our results provide insights into both theoretical design and experimental realization of nanographene materials with different exchange interactions through tuning the orbital symmetry, potentially useful for realizing magnetically operable graphene-based nanomaterials.
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Affiliation(s)
- Qingyang Du
- School of Physical Science and Technology, ShanghaiTech University, 201210, Shanghai, China
| | - Xuelei Su
- School of Physical Science and Technology, ShanghaiTech University, 201210, Shanghai, China
| | - Yufeng Liu
- Key Laboratory of Artificial Structures and Quantum Control (Ministry of Education), Shenyang National Laboratory for Materials Science, School of Physics and Astronomy, Shanghai Jiao Tong University, Shanghai, 200240, China
| | - Yashi Jiang
- Key Laboratory of Artificial Structures and Quantum Control (Ministry of Education), Shenyang National Laboratory for Materials Science, School of Physics and Astronomy, Shanghai Jiao Tong University, Shanghai, 200240, China
| | - Can Li
- Key Laboratory of Artificial Structures and Quantum Control (Ministry of Education), Shenyang National Laboratory for Materials Science, School of Physics and Astronomy, Shanghai Jiao Tong University, Shanghai, 200240, China
| | - KaKing Yan
- School of Physical Science and Technology, ShanghaiTech University, 201210, Shanghai, China
| | - Ricardo Ortiz
- Donostia International Physics Center (DIPC) - UPV/EHU, 20018, San Sebastián, Spain.
| | - Thomas Frederiksen
- Donostia International Physics Center (DIPC) - UPV/EHU, 20018, San Sebastián, Spain.
- IKERBASQUE, Basque Foundation for Science, 48013, Bilbao, Spain.
| | - Shiyong Wang
- Key Laboratory of Artificial Structures and Quantum Control (Ministry of Education), Shenyang National Laboratory for Materials Science, School of Physics and Astronomy, Shanghai Jiao Tong University, Shanghai, 200240, China.
- Tsung-Dao Lee Institute, Shanghai Jiao Tong University, Shanghai, 200240, China.
| | - Ping Yu
- School of Physical Science and Technology, ShanghaiTech University, 201210, Shanghai, China.
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20
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Yu H, Sun J, Heine T. Predicting Magnetic Coupling and Spin-Polarization Energy in Triangulene Analogues. J Chem Theory Comput 2023. [PMID: 37263582 DOI: 10.1021/acs.jctc.3c00175] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
Triangulene and its analogue metal-free magnetic systems have garnered increasing attention since their discovery. Predicting the magnetic coupling and spin-polarization energy with quantitative accuracy is beyond the predictive power of today's density functional theory (DFT) due to their intrinsic multireference character. Herein, we create a benchmark dataset of 25 magnetic systems with nonlocal spin densities, including the triangulene monomer, dimer, and their analogues. We calculate the magnetic coupling (J) and spin-polarization energy (ΔEspin) of these systems using complete active space self-consistent field (CASSCF) and coupled-cluster methods as high-quality reference values. This reference data is then used to benchmark 22 DFT functionals commonly used in material science. Our results show that, while some functionals consistently correctly predict the qualitative character of the ground state, achieving quantitative accuracy with small relative errors is currently not feasible. PBE0, M06-2X, and MN15 are predicting the correct electronic ground state for all systems investigated here and also have the lowest mean absolute error for predicting both ΔEspin (0.34, 0.32, and 0.31 eV) and J (11.74, 12.66, and 10.64 meV). They may therefore also serve as starting points for higher-level methods such as the GW or the random phase approximation. As other functionals fail for the prediction of the ground state, they cannot be recommended for metal-free magnetic systems.
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Affiliation(s)
- Hongde Yu
- Faculty of Chemistry and Food Chemistry, TU Dresden, 01069 Dresden, Germany
| | - Jianwei Sun
- Department of Physics and Engineering Physics, Tulane University, New Orleans, Louisiana 70118, United States
| | - Thomas Heine
- Faculty of Chemistry and Food Chemistry, TU Dresden, 01069 Dresden, Germany
- Institute of Resource Ecology, Helmholtz-Zentrum Dresden-Rossendorf, 04316 Leipzig, Germany
- Department of Chemistry, Yonsei University and IBS CNM, Seoul 120-749, Korea
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21
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Varandas AJC. Carbon-[ n]Triangulenes and Sila-[ n]Triangulenes: Which Are Planar? J Phys Chem A 2023. [PMID: 37256705 DOI: 10.1021/acs.jpca.3c01820] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
Using our recently suggested concept of a quasi-molecule ("tile") and, in the case of the planarity here at stake, its generalization to larger than tetratomics, we explain why carbon [n]triangulenes tend to be planar, while hybrids, where just a few or even all a- or b-type carbon atoms are silicon-substituted (sila-[n]triangulenes), tend to be planar/nonplanar when compared with the unsubstituted carbon-[n]triangulenes. Because other spin states of the parent carbon- and sila-[n]triangulenes tend to correlate with the same tiles, it is conjectured that no structural changes are expected to depend on their spin state. Other polycyclic and sila-compounds are also discussed.
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Affiliation(s)
- A J C Varandas
- School of Physics and Physical Engineering, Qufu Normal University, Qufu 273165, P. R. China
- Department of Physics, Universidade Federal do Espí rito Santo, 29075-910 Vitória, Brazil
- Department of Chemistry and Coimbra Chemistry Centre, University of Coimbra 3004-535 Coimbra, Portugal
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22
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Turco E, Bernhardt A, Krane N, Valenta L, Fasel R, Juríček M, Ruffieux P. Observation of the Magnetic Ground State of the Two Smallest Triangular Nanographenes. JACS AU 2023; 3:1358-1364. [PMID: 37234116 PMCID: PMC10207087 DOI: 10.1021/jacsau.2c00666] [Citation(s) in RCA: 13] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 12/06/2022] [Revised: 02/02/2023] [Accepted: 02/02/2023] [Indexed: 05/27/2023]
Abstract
Fusion of three benzene rings in a triangular fashion gives rise to the smallest open-shell graphene fragment, the phenalenyl radical, whose π-extension leads to an entire family of non-Kekulé triangular nanographenes with high-spin ground states. Here, we report the first synthesis of unsubstituted phenalenyl on a Au(111) surface, which is achieved by combining in-solution synthesis of the hydro-precursor and on-surface activation by atomic manipulation, using the tip of a scanning tunneling microscope. Single-molecule structural and electronic characterizations confirm its open-shell S = 1/2 ground state that gives rise to Kondo screening on the Au(111) surface. In addition, we compare the phenalenyl's electronic properties with those of triangulene, the second homologue in the series, whose S = 1 ground state induces an underscreened Kondo effect. Our results set a new lower size limit in the on-surface synthesis of magnetic nanographenes that can serve as building blocks for the realization of new exotic quantum phases of matter.
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Affiliation(s)
- Elia Turco
- nanotech@surfaces
Laboratory, Empa−Swiss Federal Laboratories
for Materials Science and Technology, 8600 Dübendorf, Switzerland
| | - Annika Bernhardt
- Department
of Chemistry, University of Zurich, Winterthurerstrasse 190, 8057 Zurich, Switzerland
| | - Nils Krane
- nanotech@surfaces
Laboratory, Empa−Swiss Federal Laboratories
for Materials Science and Technology, 8600 Dübendorf, Switzerland
| | - Leoš Valenta
- Department
of Chemistry, University of Zurich, Winterthurerstrasse 190, 8057 Zurich, Switzerland
| | - Roman Fasel
- nanotech@surfaces
Laboratory, Empa−Swiss Federal Laboratories
for Materials Science and Technology, 8600 Dübendorf, Switzerland
- Department
of Chemistry, Biochemistry and Pharmaceutical Sciences, University of Bern, 3012 Bern, Switzerland
| | - Michal Juríček
- Department
of Chemistry, University of Zurich, Winterthurerstrasse 190, 8057 Zurich, Switzerland
| | - Pascal Ruffieux
- nanotech@surfaces
Laboratory, Empa−Swiss Federal Laboratories
for Materials Science and Technology, 8600 Dübendorf, Switzerland
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23
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Wang T, Angulo-Portugal P, Berdonces-Layunta A, Jancarik A, Gourdon A, Holec J, Kumar M, Soler D, Jelinek P, Casanova D, Corso M, de Oteyza DG, Calupitan JP. Tuning the Diradical Character of Pentacene Derivatives via Non-Benzenoid Coupling Motifs. J Am Chem Soc 2023; 145:10333-10341. [PMID: 37099608 PMCID: PMC10176464 DOI: 10.1021/jacs.3c02027] [Citation(s) in RCA: 7] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2023] [Indexed: 04/27/2023]
Abstract
The development of functional organic molecules requires structures of increasing size and complexity, which are typically obtained by the covalent coupling of smaller building blocks. Herein, with the aid of high-resolution scanning tunneling microscopy/spectroscopy and density functional theory, the coupling of a sterically demanded pentacene derivative on Au(111) into fused dimers connected by non-benzenoid rings was studied. The diradical character of the products was tuned according to the coupling section. In particular, the antiaromaticity of cyclobutadiene as the coupling motif and its position within the structure play a decisive role in shifting the natural orbital occupancies toward a stronger diradical electronic character. Understanding these structure-property relations is desirable not only for fundamental reasons but also for designing new complex and functional molecular structures.
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Affiliation(s)
- Tao Wang
- Donostia
International Physics Center, 20018 San Sebastián, Spain
- Centro
de Física de Materiales (CFM-MPC), CSIC-UPV/EHU, 20018 San Sebastián, Spain
| | | | - Alejandro Berdonces-Layunta
- Donostia
International Physics Center, 20018 San Sebastián, Spain
- Centro
de Física de Materiales (CFM-MPC), CSIC-UPV/EHU, 20018 San Sebastián, Spain
| | - Andrej Jancarik
- Univ.
Bordeaux, CNRS, Centre de Recherche Paul Pascal, CRPP, UMR 5031, 33600 Pessac, France
| | - André Gourdon
- CEMES-CNRS, 29 Rue J. Marvig, 31055 Toulouse, France
| | - Jan Holec
- CEMES-CNRS, 29 Rue J. Marvig, 31055 Toulouse, France
| | - Manish Kumar
- Institute
of Physics of the Czech Academy of Sciences, Cukrovarnicka 10, 162 00 Praha, Czech
Republic
| | - Diego Soler
- Institute
of Physics of the Czech Academy of Sciences, Cukrovarnicka 10, 162 00 Praha, Czech
Republic
| | - Pavel Jelinek
- Institute
of Physics of the Czech Academy of Sciences, Cukrovarnicka 10, 162 00 Praha, Czech
Republic
| | - David Casanova
- Donostia
International Physics Center, 20018 San Sebastián, Spain
- Ikerbasque,
Basque Foundation for Science, 48009 Bilbao, Spain
| | - Martina Corso
- Donostia
International Physics Center, 20018 San Sebastián, Spain
- Centro
de Física de Materiales (CFM-MPC), CSIC-UPV/EHU, 20018 San Sebastián, Spain
| | - Dimas G. de Oteyza
- Donostia
International Physics Center, 20018 San Sebastián, Spain
- Nanomaterials
and Nanotechnology Research Center (CINN), CSIC-UNIOVI-PA, 33940 El Entrego, Spain
| | - Jan Patrick Calupitan
- Donostia
International Physics Center, 20018 San Sebastián, Spain
- Centro
de Física de Materiales (CFM-MPC), CSIC-UPV/EHU, 20018 San Sebastián, Spain
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24
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Wang T, Fan Q, Zhu J. Steering On-Surface Reactions by Kinetic and Thermodynamic Strategies. J Phys Chem Lett 2023; 14:2251-2262. [PMID: 36821589 DOI: 10.1021/acs.jpclett.3c00001] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/18/2023]
Abstract
On-surface synthesis has emerged as a powerful tool to fabricate various functional low-dimensional nanostructures with atomic precision, thus becoming a promising platform for the preparation of next-generation semiconductive, magnetic, and topological nanodevices. With the aid of scanning tunneling microscopy/spectroscopy and noncontact atomic force microscopy, both the chemical structures and physical properties of the obtained products can be well characterized. A major challenge in this field is how to efficiently steer reaction pathways and improve the yield/quality of products. To address this problem, in recent years various kinetic and thermodynamic strategies have been successfully employed to control on-surface reactions. In this Perspective, we discuss these strategies in view of basic reaction steps on surfaces, including molecular adsorption, diffusion, and reaction. We hope this Perspective will help readers to deepen the understanding of the mechanisms of on-surface reactions and rationally design reaction procedures for the fabrication of high-quality functional nanomaterials on surfaces.
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Affiliation(s)
- Tao Wang
- Department of Pharmacy, The First Affiliated Hospital of USTC, Division of Life Sciences and Medicine, and National Synchrotron Radiation Laboratory, University of Science and Technology of China, Hefei 230029, P. R. China
- Donostia International Physics Center, San Sebastián 20018, Spain
| | - Qitang Fan
- Hefei National Research Center for Physical Sciences at the Microscale and Synergetic Innovation Center of Quantum Information & Quantum Physics, University of Science and Technology of China, Hefei 230026, P. R. China
| | - Junfa Zhu
- Department of Pharmacy, The First Affiliated Hospital of USTC, Division of Life Sciences and Medicine, and National Synchrotron Radiation Laboratory, University of Science and Technology of China, Hefei 230029, P. R. China
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25
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Toksabay S, Leisegang M, Christ A, Härtl P, Krebs J, Marder TB, Haldar S, Heinze S, Bode M, Krueger A. Controlled Formation of Porous 2D Lattices from C 3 -symmetric Ph 6 -Me-Tribenzotriquinacene-OAc 3. Chemistry 2023; 29:e202203187. [PMID: 36346617 DOI: 10.1002/chem.202203187] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2022] [Revised: 11/04/2022] [Accepted: 11/07/2022] [Indexed: 11/09/2022]
Abstract
The on-surface self-assembly of molecules to form holey nanographenes is a promising approach to control the properties of the resulting 2D lattice. Usually, planar molecules are utilized to prepare flat, structurally confined molecular layers, with only a few recent examples of warped precursors. However, control of the superstructures is limited thus far. Herein, we report the temperature-controlled self-assembly of a bowl-shaped, acetylated C3 -symmetric hexaphenyltribenzotriquinacene derivative on Cu(111). Combining scanning tunneling microscopy (STM) and density functional theory (DFT) confirms the formation of highly differing arrangements starting with π-stacked bowl-to-bowl dimers at low coverage at room temperature via chiral honeycomb structures, an intermediate trigonal superstructure, followed by a fully carbon-based, flattened hexagonal superstructure formed by on-surface deacetylation, which is proposed as a precursor for holey graphene networks with unique defect structures.
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Affiliation(s)
- Sinem Toksabay
- Institute for Organic Chemistry, Julius-Maximilians-Universität Würzburg, Am Hubland, 97074, Würzburg, Germany
| | - Markus Leisegang
- Physikalisches Institut Experimentelle Physik II, Julius-Maximilians-Universität Würzburg, Am Hubland, 97074, Würzburg, Germany
| | - Andreas Christ
- Physikalisches Institut Experimentelle Physik II, Julius-Maximilians-Universität Würzburg, Am Hubland, 97074, Würzburg, Germany
| | - Patrick Härtl
- Physikalisches Institut Experimentelle Physik II, Julius-Maximilians-Universität Würzburg, Am Hubland, 97074, Würzburg, Germany
| | - Johannes Krebs
- Institute for Inorganic Chemistry and Institute for Sustainable Chemistry & Catalysis with Boron, Julius-Maximilians-Universität Würzburg, Am Hubland, 97074, Würzburg, Germany
| | - Todd B Marder
- Institute for Inorganic Chemistry and Institute for Sustainable Chemistry & Catalysis with Boron, Julius-Maximilians-Universität Würzburg, Am Hubland, 97074, Würzburg, Germany
| | - Soumyajyoti Haldar
- Institute of Theoretical Physics and Astrophysics, University of Kiel, Leibnizstrasse 15, 24098, Kiel, Germany
| | - Stefan Heinze
- Institute of Theoretical Physics and Astrophysics, University of Kiel, Leibnizstrasse 15, 24098, Kiel, Germany
| | - Matthias Bode
- Physikalisches Institut Experimentelle Physik II, Julius-Maximilians-Universität Würzburg, Am Hubland, 97074, Würzburg, Germany.,Wilhelm Conrad Röntgen-Center for Complex Material Systems (RCCM), Julius-Maximilians-Universität Würzburg, Am Hubland, 97074, Würzburg, Germany
| | - Anke Krueger
- Institute for Organic Chemistry, Julius-Maximilians-Universität Würzburg, Am Hubland, 97074, Würzburg, Germany.,Institute of Organic Chemistry, University of Stuttgart, Pfaffenwaldring 55, 70569, Stuttgart, Germany
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26
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Steering Large Magnetic Exchange Coupling in Nanographenes near the Closed-Shell to Open-Shell Transition. J Am Chem Soc 2023; 145:2968-2974. [PMID: 36708335 DOI: 10.1021/jacs.2c11431] [Citation(s) in RCA: 10] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
The design of open-shell carbon-based nanomaterials is at the vanguard of materials science, steered by their beneficial magnetic properties like weaker spin-orbit coupling than that of transition metal atoms and larger spin delocalization, which are of potential relevance for future spintronics and quantum technologies. A key parameter in magnetic materials is the magnetic exchange coupling (MEC) between unpaired spins, which should be large enough to allow device operation at practical temperatures. In this work, we theoretically and experimentally explore three distinct families of nanographenes (NGs) (A, B, and C) featuring majority zigzag peripheries. Through many-body calculations, we identify a transition from a closed-shell ground state to an open-shell ground state upon an increase of the molecular size. Our predictions indicate that the largest MEC for open-shell NGs occurs in proximity to the transition between closed-shell and open-shell states. Such predictions are corroborated by the on-surface syntheses and structural, electronic, and magnetic characterizations of three NGs (A[3,5], B[4,5], and C[4,3]), which are the smallest open-shell systems in their respective chemical families and are thus located the closest to the transition boundary. Notably, two of the NGs (B[4,5] and C[4,3]) feature record values of MEC (close to 200 meV) measured on the Au(111) surface. Our strategy for maximizing the MEC provides perspectives for designing carbon nanomaterials with robust magnetic ground states.
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27
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Affiliation(s)
- P Jelínek
- Institute of Physics, Czech Academy of Sciences, Prague, Czech Republic.
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28
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Li E, Lyu CK, Chen C, Xie H, Zhang J, Lam JWY, Tang BZ, Lin N. On-surface synthesis and spontaneous segregation of conjugated tetraphenylethylene macrocycles. Commun Chem 2022; 5:174. [PMID: 36697742 PMCID: PMC9814618 DOI: 10.1038/s42004-022-00794-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2022] [Accepted: 12/07/2022] [Indexed: 12/24/2022] Open
Abstract
Creating conjugated macrocycles has attracted extensive research interest because their unique chemical and physical properties, such as conformational flexibility, intrinsic inner cavities and aromaticity/antiaromaticity, make these systems appealing building blocks for functional supramolecular materials. Here, we report the synthesis of four-, six- and eight-membered tetraphenylethylene (TPE)-based macrocycles on Ag(111) via on-surface Ullmann coupling reactions. The as-synthesized macrocycles are spontaneously segregated on the surface and self-assemble as large-area two-dimensional mono-component supramolecular crystals, as characterized by scanning tunneling microscopy (STM). We propose that the synthesis benefits from the conformational flexibility of the TPE backbone in distinctive multi-step reaction pathways. This study opens up opportunities for exploring the photophysical properties of TPE-based macrocycles.
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Affiliation(s)
- En Li
- grid.24515.370000 0004 1937 1450Department of Physics, The Hong Kong University of Science and Technology, Clear Water Bay, Hong Kong, China
| | - Cheng-Kun Lyu
- grid.24515.370000 0004 1937 1450Department of Physics, The Hong Kong University of Science and Technology, Clear Water Bay, Hong Kong, China
| | - Chengyi Chen
- grid.24515.370000 0004 1937 1450Department of Physics, The Hong Kong University of Science and Technology, Clear Water Bay, Hong Kong, China
| | - Huilin Xie
- grid.24515.370000 0004 1937 1450Department of Chemistry, Hong Kong Branch of Chinese National Engineering Research Center for Tissue Restoration and Reconstruction, The Hong Kong University of Science and Technology, Clear Water Bay, Hong Kong, China
| | - Jianyu Zhang
- grid.24515.370000 0004 1937 1450Department of Chemistry, Hong Kong Branch of Chinese National Engineering Research Center for Tissue Restoration and Reconstruction, The Hong Kong University of Science and Technology, Clear Water Bay, Hong Kong, China
| | - Jacky Wing Yip Lam
- grid.24515.370000 0004 1937 1450Department of Chemistry, Hong Kong Branch of Chinese National Engineering Research Center for Tissue Restoration and Reconstruction, The Hong Kong University of Science and Technology, Clear Water Bay, Hong Kong, China
| | - Ben Zhong Tang
- grid.24515.370000 0004 1937 1450Department of Chemistry, Hong Kong Branch of Chinese National Engineering Research Center for Tissue Restoration and Reconstruction, The Hong Kong University of Science and Technology, Clear Water Bay, Hong Kong, China ,grid.10784.3a0000 0004 1937 0482School of Science and Engineering, Shenzhen Institute of Aggregate Science and Technology, The Chinese University of Hong Kong, Shenzhen, Guangdong China
| | - Nian Lin
- grid.24515.370000 0004 1937 1450Department of Physics, The Hong Kong University of Science and Technology, Clear Water Bay, Hong Kong, China
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29
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Ni X, Huang H, Brédas JL. Organic Higher-Order Topological Insulators: Heterotriangulene-Based Covalent Organic Frameworks. J Am Chem Soc 2022; 144:22778-22786. [PMID: 36469524 DOI: 10.1021/jacs.2c11229] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
The ability to design and control the chemical characteristics of covalent organic frameworks (COFs) offers a new avenue for the development of functional materials, especially with respect to topological properties. Based on density functional theory calculations, by varying the core units through the choice of bridging groups [O, C═O, CH2, or C(CH3)2] and the linker units [acetylene, diacetylene, or benzene], we have designed heterotriangulene-based COFs that are predicted to be two-dimensional higher-order topological insulators (TIs). The higher-order TI characteristics of these COFs are identified via their topological invariants and the presence of in-gap topological corner modes and gapped edge states. The frontier molecular orbital energies of the building moieties play an important role in determining the size of the higher-order TI gap, which we find to be highly dependent on linker units. We also examined the deposition of the COFs on a boron nitride substrate to assess the feasibility of experimental observation of a higher-order TI phase in the organic layer. This work thus provides new insights into heterotriangulene-based COFs and guidance for the exploration of purely organic topological materials.
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Affiliation(s)
- Xiaojuan Ni
- Department of Chemistry and Biochemistry, The University of Arizona, Tucson, Arizona85721-0088, United States
| | - Huaqing Huang
- School of Physics, Peking University, Beijing100871, China.,Collaborative Innovation Center of Quantum Matter, Beijing100871, China
| | - Jean-Luc Brédas
- Department of Chemistry and Biochemistry, The University of Arizona, Tucson, Arizona85721-0088, United States
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30
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Martins Quintela MFC, Peres NMR. Wannier excitons confined in hexagonal boron nitride triangular quantum dots. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2022; 35:035302. [PMID: 36368044 DOI: 10.1088/1361-648x/aca24f] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/19/2022] [Accepted: 11/11/2022] [Indexed: 06/16/2023]
Abstract
With the ever-growing interest in quantum computing, understanding the behavior of excitons in monolayer quantum dots has become a topic of great relevance. In this paper, we consider a Wannier exciton confined in a triangular quantum dot of hexagonal boron nitride. We begin by outlining the adequate basis functions to describe a particle in a triangular enclosure, analyzing their degeneracy and symmetries. Afterwards, we discuss the excitonic Hamiltonian inside the quantum dot and study the influence of the quantum dot dimensions on the excitonic states.
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Affiliation(s)
- M F C Martins Quintela
- Department of Physics and Centre of Physics of the Universities of Minho and Porto (CF-UM-UP), Campus of Gualtar, 4710-057 Braga, Portugal
- International Iberian Nanotechnology Laboratory (INL), Av. Mestre José Veiga, 4715-330 Braga, Portugal
| | - N M R Peres
- Department of Physics and Centre of Physics of the Universities of Minho and Porto (CF-UM-UP), Campus of Gualtar, 4710-057 Braga, Portugal
- International Iberian Nanotechnology Laboratory (INL), Av. Mestre José Veiga, 4715-330 Braga, Portugal
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31
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Zhang H, Pink M, Wang Y, Rajca S, Rajca A. High-Spin S = 3/2 Ground-State Aminyl Triradicals: Toward High-Spin Oligo-Aza Nanographenes. J Am Chem Soc 2022; 144:19576-19591. [PMID: 36251959 PMCID: PMC10438970 DOI: 10.1021/jacs.2c09241] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
We report high-spin aminyl triradicals with near-planar triphenylene backbones. Near-planarity of the fused aminyl radicals and the 2,6,10-triphenylene ferromagnetic coupling unit (FCU), magnetically equivalent to three fused 3,4'-biphenyl FCUs, assures an effective 2pπ-2pπ overlap within the cross-conjugated π-system, leading to an S = 3/2 (quartet) ground state that is well separated from low-spin excited doublet states. Thermal populations of the low-spin (S = 1/2) excited states are detectable both by SQUID magnetometry and electron paramagnetic resonance (EPR) spectroscopy, providing doublet-quartet energy gaps, ΔEDQ, corresponding to >85% population of the quartet ground states at room temperature. Notably, EPR-based determination of ΔEDQ relies on direct detection of the quartet ground state and doublet excited states. The ΔEDQ values are 1.0-1.1 kcal mol-1, with the more sterically shielded triradical having the larger value. The half-life of the more sterically shielded triradical in 2-methyltetrahydrofuran (2-MeTHF) is about 6 h at room temperature. The less sterically shielded triradical in 2-MeTHF decomposes at 158 K with a half-life of about 4 h, while at 195 K, the half-life is still about 2 h. The dominant products of the decay of triradicals are the corresponding triamines, suggesting hydrogen atom abstraction from the solvent as the primary mechanism. This study expands the frontier of the open-shell PAHs/nanographenes, of which the unique electronic, nonlinear optical, and magnetic properties could be useful in the development of novel organic electronics, photonics, and spintronics.
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Affiliation(s)
- Hui Zhang
- Department of Chemistry, University of Nebraska, Lincoln, NE 68588-0304, United States
| | - Maren Pink
- IUMSC, Department of Chemistry, Indiana University, Bloomington, IN 47405-7102, United States
| | - Ying Wang
- Department of Chemistry, University of Nebraska, Lincoln, NE 68588-0304, United States
| | - Suchada Rajca
- Department of Chemistry, University of Nebraska, Lincoln, NE 68588-0304, United States
| | - Andrzej Rajca
- Department of Chemistry, University of Nebraska, Lincoln, NE 68588-0304, United States
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32
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Friedrich N, Menchón RE, Pozo I, Hieulle J, Vegliante A, Li J, Sánchez-Portal D, Peña D, Garcia-Lekue A, Pascual JI. Addressing Electron Spins Embedded in Metallic Graphene Nanoribbons. ACS NANO 2022; 16:14819-14826. [PMID: 36037149 PMCID: PMC9527809 DOI: 10.1021/acsnano.2c05673] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 06/09/2022] [Accepted: 08/17/2022] [Indexed: 06/15/2023]
Abstract
Spin-hosting graphene nanostructures are promising metal-free systems for elementary quantum spintronic devices. Conventionally, spins are protected from quenching by electronic band gaps, which also hinder electronic access to their quantum state. Here, we present a narrow graphene nanoribbon substitutionally doped with boron heteroatoms that combines a metallic character with the presence of localized spin 1/2 states in its interior. The ribbon was fabricated by on-surface synthesis on a Au(111) substrate. Transport measurements through ribbons suspended between the tip and the sample of a scanning tunneling microscope revealed their ballistic behavior, characteristic of metallic nanowires. Conductance spectra show fingerprints of localized spin states in the form of Kondo resonances and inelastic tunneling excitations. Density functional theory rationalizes the metallic character of the graphene nanoribbon due to the partial depopulation of the valence band induced by the boron atoms. The transferred charge builds localized magnetic moments around the boron atoms. The orthogonal symmetry of the spin-hosting state's and the valence band's wave functions protects them from mixing, maintaining the spin states localized. The combination of ballistic transport and spin localization into a single graphene nanoribbon offers the perspective of electronically addressing and controlling carbon spins in real device architectures.
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Affiliation(s)
| | - Rodrigo E. Menchón
- Donostia
International Physics Center (DIPC), 20018 Donostia-San Sebastián, Spain
| | - Iago Pozo
- CiQUS,
Centro Singular de Investigación en Química Biolóxica
e Materiais Moleculares, 15705 Santiago de Compostela, Spain
| | | | | | - Jingcheng Li
- CIC
nanoGUNE-BRTA, 20018 Donostia-San Sebastián, Spain
| | - Daniel Sánchez-Portal
- Donostia
International Physics Center (DIPC), 20018 Donostia-San Sebastián, Spain
- Centro
de Física de Materiales CSIC-UPV/EHU, 20018 Donostia-San Sebastián, Spain
| | - Diego Peña
- CiQUS,
Centro Singular de Investigación en Química Biolóxica
e Materiais Moleculares, 15705 Santiago de Compostela, Spain
| | - Aran Garcia-Lekue
- Donostia
International Physics Center (DIPC), 20018 Donostia-San Sebastián, Spain
- Ikerbasque,
Basque Foundation for Science, 48013 Bilbao, Spain
| | - José Ignacio Pascual
- CIC
nanoGUNE-BRTA, 20018 Donostia-San Sebastián, Spain
- Ikerbasque,
Basque Foundation for Science, 48013 Bilbao, Spain
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33
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Murata T, Yoshida K, Suzuki S, Ueda A, Nishida S, Kawai J, Fukui K, Sato K, Takui T, Nakasuji K, Morita Y. Double‐σ‐Bonded Close‐Shell Dimers and Peroxy‐Linked Open‐Shell Dimer Derived from a
C
3
Symmetric Trioxophenalenyl Neutral Diradical. Chemistry 2022; 28:e202201426. [DOI: 10.1002/chem.202201426] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2022] [Indexed: 11/10/2022]
Affiliation(s)
- Tsuyoshi Murata
- Department of Applied Chemistry, Faculty of Engineering Aichi Institute of Technology Yachigusa 1247, Yakusa Toyota Aichi Japan
| | - Kenta Yoshida
- Department of Chemistry Graduate School of Science Osaka University Machikaneyama 1–1 Toyonaka Osaka Japan
| | - Shuichi Suzuki
- Department of Chemistry Graduate School of Engineering Science Osaka University Machikaneyama 1–3 Toyonaka Osaka Japan
| | - Akira Ueda
- Department of Chemistry Faculty of Advanced Science and Technology Kumamoto University 2-39-1 Kurokami Chuo-ku Kumamoto Japan
| | - Shinsuke Nishida
- Department of Applied Chemistry, Faculty of Engineering Aichi Institute of Technology Yachigusa 1247, Yakusa Toyota Aichi Japan
| | - Junya Kawai
- Department of Chemistry Graduate School of Science Osaka University Machikaneyama 1–1 Toyonaka Osaka Japan
| | - Kozo Fukui
- Department of Chemistry Graduate School of Science Osaka University Machikaneyama 1–1 Toyonaka Osaka Japan
| | - Kazunobu Sato
- Department of Chemistry and Molecular Materials Science Graduate School of Science Osaka City University/Osaka Metropolitan University Sugimoto 3–3-138 Sumiyoshi-ku Osaka Japan
| | - Takeji Takui
- Department of Chemistry and Molecular Materials Science Graduate School of Science Osaka City University/Osaka Metropolitan University Sugimoto 3–3-138 Sumiyoshi-ku Osaka Japan
| | - Kazuhiro Nakasuji
- Department of Chemistry Graduate School of Science Osaka University Machikaneyama 1–1 Toyonaka Osaka Japan
| | - Yasushi Morita
- Department of Applied Chemistry, Faculty of Engineering Aichi Institute of Technology Yachigusa 1247, Yakusa Toyota Aichi Japan
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34
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de Oteyza DG, Frederiksen T. Carbon-based nanostructures as a versatile platform for tunable π-magnetism. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2022; 34:443001. [PMID: 35977474 DOI: 10.1088/1361-648x/ac8a7f] [Citation(s) in RCA: 18] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/08/2022] [Accepted: 08/17/2022] [Indexed: 06/15/2023]
Abstract
Emergence ofπ-magnetism in open-shell nanographenes has been theoretically predicted decades ago but their experimental characterization was elusive due to the strong chemical reactivity that makes their synthesis and stabilization difficult. In recent years, on-surface synthesis under vacuum conditions has provided unprecedented opportunities for atomically precise engineering of nanographenes, which in combination with scanning probe techniques have led to a substantial progress in our capabilities to realize localized electron spin states and to control electron spin interactions at the atomic scale. Here we review the essential concepts and the remarkable advances in the last few years, and outline the versatility of carbon-basedπ-magnetic materials as an interesting platform for applications in spintronics and quantum technologies.
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Affiliation(s)
- Dimas G de Oteyza
- Nanomaterials and Nanotechnology Research Center (CINN), CSIC-UNIOVI-PA, E-33940 El Entrego, Spain
- Donostia International Physics Center (DIPC)-UPV/EHU, E-20018 San Sebastián, Spain
| | - Thomas Frederiksen
- Donostia International Physics Center (DIPC)-UPV/EHU, E-20018 San Sebastián, Spain
- Ikerbasque, Basque Foundation for Science, E-48013 Bilbao, Spain
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35
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Lisiecki J, Szabelski P. Monte Carlo simulation of the surface-assisted self-assembly of metal-organic precursors comprising phenanthrene building blocks. Colloids Surf A Physicochem Eng Asp 2022. [DOI: 10.1016/j.colsurfa.2022.129177] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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36
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Wen ECH, Jacobse PH, Jiang J, Wang Z, McCurdy RD, Louie SG, Crommie MF, Fischer FR. Magnetic Interactions in Substitutional Core-Doped Graphene Nanoribbons. J Am Chem Soc 2022; 144:13696-13703. [PMID: 35867847 DOI: 10.1021/jacs.2c04432] [Citation(s) in RCA: 14] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The design of a spin imbalance within the crystallographic unit cell of bottom-up engineered 1D graphene nanoribbons (GNRs) gives rise to nonzero magnetic moments within each cell. Here, we demonstrate the bottom-up assembly and spectroscopic characterization of a one-dimensional Kondo spin chain formed by a chevron-type GNR (cGNR) physisorbed on Au(111). Substitutional nitrogen core doping introduces a pair of low-lying occupied states per monomer within the semiconducting gap of cGNRs. Charging resulting from the interaction with the gold substrate quenches one electronic state for each monomer, leaving behind a 1D chain of radical cations commensurate with the unit cell of the ribbon. Scanning tunneling microscopy (STM) and spectroscopy (STS) reveal the signature of a Kondo resonance emerging from the interaction of S = 1/2 spin centers in each monomer core with itinerant electrons in the Au substrate. STM tip lift-off experiments locally reduce the effective screening of the unpaired radical cation being lifted, revealing a robust exchange coupling between neighboring spin centers. First-principles DFT-LSDA calculations support the presence of magnetic moments in the core of this GNR when it is placed on Au.
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Affiliation(s)
- Ethan Chi Ho Wen
- Department of Chemistry, University of California, Berkeley, California 94720, United States
| | - Peter H Jacobse
- Department of Physics, University of California, Berkeley, California 94720, United States
| | - Jingwei Jiang
- Department of Physics, University of California, Berkeley, California 94720, United States.,Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States
| | - Ziyi Wang
- Department of Physics, University of California, Berkeley, California 94720, United States
| | - Ryan D McCurdy
- Department of Chemistry, University of California, Berkeley, California 94720, United States
| | - Steven G Louie
- Department of Physics, University of California, Berkeley, California 94720, United States.,Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States
| | - Michael F Crommie
- Department of Physics, University of California, Berkeley, California 94720, United States.,Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States.,Kavli Energy NanoSciences Institute at the University of California Berkeley and the Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States
| | - Felix R Fischer
- Department of Chemistry, University of California, Berkeley, California 94720, United States.,Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States.,Kavli Energy NanoSciences Institute at the University of California Berkeley and the Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States
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37
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Gu Y, Qiu Z, Müllen K. Nanographenes and Graphene Nanoribbons as Multitalents of Present and Future Materials Science. J Am Chem Soc 2022; 144:11499-11524. [PMID: 35671225 PMCID: PMC9264366 DOI: 10.1021/jacs.2c02491] [Citation(s) in RCA: 39] [Impact Index Per Article: 19.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
As cut-outs from a graphene sheet, nanographenes (NGs) and graphene nanoribbons (GNRs) are ideal cases with which to connect the world of molecules with that of bulk carbon materials. While various top-down approaches have been developed to produce such nanostructures in high yields, in the present perspective, precision structural control is emphasized for the length, width, and edge structures of NGs and GNRs achieved by modern solution and on-surface syntheses. Their structural possibilities have been further extended from "flatland" to the three-dimensional world, where chirality and handedness are the jewels in the crown. In addition to properties exhibited at the molecular level, self-assembly and thin-film structures cannot be neglected, which emphasizes the importance of processing techniques. With the rich toolkit of chemistry in hand, NGs and GNRs can be endowed with versatile properties and functions ranging from stimulated emission to spintronics and from bioimaging to energy storage, thus demonstrating their multitalents in present and future materials science.
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Affiliation(s)
- Yanwei Gu
- Max
Planck Institute for Polymer Research, Ackermannweg 10, 55128 Mainz, Germany
| | - Zijie Qiu
- Max
Planck Institute for Polymer Research, Ackermannweg 10, 55128 Mainz, Germany
- Shenzhen
Institute of Aggregate Science and Technology, School of Science and
Engineering, The Chinese University of Hong
Kong, Shenzhen 518172, China
| | - Klaus Müllen
- Max
Planck Institute for Polymer Research, Ackermannweg 10, 55128 Mainz, Germany
- Institute
for Physical Chemistry , Johannes Gutenberg
University Mainz, Duesbergweg
10-14, 55128 Mainz, Germany
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38
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Cheng S, Xue Z, Li C, Liu Y, Xiang L, Ke Y, Yan K, Wang S, Yu P. On-surface synthesis of triangulene trimers via dehydration reaction. Nat Commun 2022; 13:1705. [PMID: 35361812 PMCID: PMC8971457 DOI: 10.1038/s41467-022-29371-9] [Citation(s) in RCA: 17] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2021] [Accepted: 03/04/2022] [Indexed: 11/08/2022] Open
Abstract
Triangulene and its homologues are of considerable interest for molecular spintronics due to their high-spin ground states as well as the potential for constructing high spin frameworks. Realizing triangulene-based high-spin system on surface is challenging but of particular importance for understanding π-electron magnetism. Here, we report two approaches to generate triangulene trimers on Au(111) by using surface-assisted dehydration and alkyne trimerization, respectively. We find that the developed dehydration reaction shows much higher chemoselectivity thus resulting in significant promotion of product yield compared to that using alkyne trimerization approach, through cutting the side reaction path. Combined with spin-polarized density functional theory calculations, scanning tunneling spectroscopy measurements identify the septuple (S = 3) high-spin ground state and quantify the collective ferromagnetic interaction among three triangulene units. Our results demonstrate the approaches to fabricate high-quality triangulene-based high spin systems and understand their magnetic interactions, which are essential for realizing carbon-based spintronic devices.
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Affiliation(s)
- Suqin Cheng
- School of Physical Science and Technology, ShanghaiTech University, 201210, Shanghai, China
| | - Zhijie Xue
- School of Physical Science and Technology, ShanghaiTech University, 201210, Shanghai, China
| | - Can Li
- Key Laboratory of Artificial Structures and Quantum Control (Ministry of Education), Shenyang National Laboratory for Materials Science, School of Physics and Astronomy, Shanghai Jiao Tong University, 200240, Shanghai, China
| | - Yufeng Liu
- Key Laboratory of Artificial Structures and Quantum Control (Ministry of Education), Shenyang National Laboratory for Materials Science, School of Physics and Astronomy, Shanghai Jiao Tong University, 200240, Shanghai, China
| | - Longjun Xiang
- School of Physical Science and Technology, ShanghaiTech University, 201210, Shanghai, China
| | - Youqi Ke
- School of Physical Science and Technology, ShanghaiTech University, 201210, Shanghai, China
| | - Kaking Yan
- School of Physical Science and Technology, ShanghaiTech University, 201210, Shanghai, China
| | - Shiyong Wang
- Key Laboratory of Artificial Structures and Quantum Control (Ministry of Education), Shenyang National Laboratory for Materials Science, School of Physics and Astronomy, Shanghai Jiao Tong University, 200240, Shanghai, China.
- Tsung-Dao Lee Institute, Shanghai Jiao Tong University, 200240, Shanghai, China.
| | - Ping Yu
- School of Physical Science and Technology, ShanghaiTech University, 201210, Shanghai, China.
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39
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Wang T, Berdonces-Layunta A, Friedrich N, Vilas-Varela M, Calupitan JP, Pascual JI, Peña D, Casanova D, Corso M, de Oteyza DG. Aza-Triangulene: On-Surface Synthesis and Electronic and Magnetic Properties. J Am Chem Soc 2022; 144:4522-4529. [PMID: 35254059 PMCID: PMC8931755 DOI: 10.1021/jacs.1c12618] [Citation(s) in RCA: 32] [Impact Index Per Article: 16.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
![]()
Nitrogen
heteroatom doping into a triangulene molecule allows tuning
its magnetic state. However, the synthesis of the nitrogen-doped triangulene
(aza-triangulene) has been challenging. Herein, we report the successful
synthesis of aza-triangulene on the Au(111) and Ag(111) surfaces,
along with their characterizations by scanning tunneling microscopy
and spectroscopy in combination with density functional theory (DFT)
calculations. Aza-triangulenes were obtained by reducing ketone-substituted
precursors. Exposure to atomic hydrogen followed by thermal annealing
and, when necessary, manipulations with the scanning probe afforded
the target product. We demonstrate that on Au(111), aza-triangulene
donates an electron to the substrate and exhibits an open-shell triplet
ground state. This is derived from the different Kondo resonances
of the final aza-triangulene product and a series of intermediates
on Au(111). Experimentally mapped molecular orbitals match with DFT-calculated
counterparts for a positively charged aza-triangulene. In contrast,
aza-triangulene on Ag(111) receives an extra electron from the substrate
and displays a closed-shell character. Our study reveals the electronic
properties of aza-triangulene on different metal surfaces and offers
an approach for the fabrication of new hydrocarbon structures, including
reactive open-shell molecules.
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Affiliation(s)
- Tao Wang
- Donostia International Physics Center, 20018 San Sebastián, Spain
- Centro de Fisica de Materiales CFM/MPC, CSIC-UPV/EHU, 20018 San Sebastián, Spain
| | - Alejandro Berdonces-Layunta
- Donostia International Physics Center, 20018 San Sebastián, Spain
- Centro de Fisica de Materiales CFM/MPC, CSIC-UPV/EHU, 20018 San Sebastián, Spain
| | | | - Manuel Vilas-Varela
- Centro Singular de Investigación en Química Biolóxica e Materiais Moleculares (CiQUS) and Departamento de Química Orgánica, Universidade de Santiago de Compostela, 15782 Santiago de Compostela, Spain
| | | | - Jose Ignacio Pascual
- CIC NanoGUNE BRTA, 20018 San Sebastián, Spain
- Ikerbasque, Basque Foundation for Science, 48009 Bilbao, Spain
| | - Diego Peña
- Centro Singular de Investigación en Química Biolóxica e Materiais Moleculares (CiQUS) and Departamento de Química Orgánica, Universidade de Santiago de Compostela, 15782 Santiago de Compostela, Spain
| | - David Casanova
- Donostia International Physics Center, 20018 San Sebastián, Spain
- Ikerbasque, Basque Foundation for Science, 48009 Bilbao, Spain
| | - Martina Corso
- Donostia International Physics Center, 20018 San Sebastián, Spain
- Centro de Fisica de Materiales CFM/MPC, CSIC-UPV/EHU, 20018 San Sebastián, Spain
| | - Dimas G. de Oteyza
- Donostia International Physics Center, 20018 San Sebastián, Spain
- Centro de Fisica de Materiales CFM/MPC, CSIC-UPV/EHU, 20018 San Sebastián, Spain
- Ikerbasque, Basque Foundation for Science, 48009 Bilbao, Spain
- Nanomaterials and Nanotechnology Research Center (CINN), CSIC-UNIOVI-PA; 33940 El Entrego, Spain
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40
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Mishra S, Fatayer S, Fernández S, Kaiser K, Peña D, Gross L. Nonbenzenoid High-Spin Polycyclic Hydrocarbons Generated by Atom Manipulation. ACS NANO 2022; 16:3264-3271. [PMID: 35130690 DOI: 10.1021/acsnano.1c11157] [Citation(s) in RCA: 13] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
We report the on-surface synthesis of a nonbenzenoid 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 open-shell doublet and triplet ground states, respectively. Our results should have bearings on the synthesis of nonbenzenoid high-spin polycyclic frameworks with magnetism beyond Lieb's theorem.
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Affiliation(s)
| | | | - Saleta Fernández
- Centro Singular de Investigación en Química Biolóxica e Materiais Moleculares (CiQUS) and Departamento de Química Orgánica, Universidade de Santiago de Compostela, 15782 Santiago de Compostela, Spain
| | | | - Diego Peña
- Centro Singular de Investigación en Química Biolóxica e Materiais Moleculares (CiQUS) and Departamento de Química Orgánica, Universidade de Santiago de Compostela, 15782 Santiago de Compostela, Spain
| | - Leo Gross
- IBM Research-Zurich, 8803 Rüschlikon, Switzerland
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41
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Abstract
Triangulene is the smallest non-Kekulé graphene fragment known as Clar's hydrocarbon. Due to its open-shell electronic structure, triangulene is a promising molecular building block of carbon-based organic materials for spintronics and quantum molecular science. It comprises six benzenoid rings arranged in a triangular shape with two unpaired electrons delocalized over the entire conjugated core, making this molecule highly reactive. A triplet ground state is predicted for this hydrocarbon by Ovchinnikov's rule, or Lieb's theorem, in accord with Hund's rule. The pioneering work on triangulene was performed almost 70 years ago by Erich Clar, who attempted to prepare the pristine compound. Since then, several synthetic approaches to prepare this molecule have been exploited. The extreme reactivity of triangulene can be circumvented using on-surface techniques or by installation of sterically demanding substituents, which kinetically stabilize the diradical core against oligomerization in solution. The first two examples of a persistent derivative of triangulene were simultaneously and independently developed last year. This article presents a historical development in the synthesis of triangulene and its derivatives and outlines possible future applications in ferromagnetic materials, electrically conductive polymers or quantum computing. A historical development of synthetic efforts to “tame” triangulene—an iconic non-Kekulé graphene fragment known as a Clar's hydrocarbon—up to the most recent advancements that open new possibilities in the design of carbon-based spin materials.![]()
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Affiliation(s)
- Leoš Valenta
- Department of Chemistry, University of Zurich, Winterthurerstrasse 190, 8057 Zurich, Switzerland.
| | - Michal Juríček
- Department of Chemistry, University of Zurich, Winterthurerstrasse 190, 8057 Zurich, Switzerland.
- Prievidza Chemical Society, M. Hodžu 10/16, 971 01 Prievidza, Slovak Republic
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42
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Spin State Switching in Heptauthrene Nanostructure by Electric Field: Computational Study. Int J Mol Sci 2021; 22:ijms222413364. [PMID: 34948161 PMCID: PMC8705984 DOI: 10.3390/ijms222413364] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2021] [Revised: 11/26/2021] [Accepted: 11/29/2021] [Indexed: 11/23/2022] Open
Abstract
Recent experimental studies proved the presence of the triplet spin state in atomically precise heptauthrene nanostructure of nanographene type (composed of two interconnected triangles with zigzag edge). In the paper, we report the computational study predicting the possibility of controlling this spin state with an external in-plane electric field by causing the spin switching. We construct and discuss the ground state magnetic phase diagram involving S=1 (triplet) state, S=0 antiferromagnetic state and non-magnetic state and predict the switching possibility with the critical electric field of the order of 0.1 V/Å. We discuss the spin distribution across the nanostructure, finding its concentration along the longest zigzag edge. To model our system of interest, we use the mean-field Hubbard Hamiltonian, taking into account the in-plane external electric field as well as the in-plane magnetic field (in a form of the exchange field from the substrate). We also assess the effect of uniaxial strain on the magnetic phase diagram.
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43
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Mishra S, Catarina G, Wu F, Ortiz R, Jacob D, Eimre K, Ma J, Pignedoli CA, Feng X, Ruffieux P, Fernández-Rossier J, Fasel R. Observation of fractional edge excitations in nanographene spin chains. Nature 2021; 598:287-292. [PMID: 34645998 DOI: 10.1038/s41586-021-03842-3] [Citation(s) in RCA: 71] [Impact Index Per Article: 23.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2021] [Accepted: 07/20/2021] [Indexed: 11/09/2022]
Abstract
Fractionalization is a phenomenon in which strong interactions in a quantum system drive the emergence of excitations with quantum numbers that are absent in the building blocks. Outstanding examples are excitations with charge e/3 in the fractional quantum Hall effect1,2, solitons in one-dimensional conducting polymers3,4 and Majorana states in topological superconductors5. Fractionalization is also predicted to manifest itself in low-dimensional quantum magnets, such as one-dimensional antiferromagnetic S = 1 chains. The fundamental features of this system are gapped excitations in the bulk6 and, remarkably, S = 1/2 edge states at the chain termini7-9, leading to a four-fold degenerate ground state that reflects the underlying symmetry-protected topological order10,11. Here, we use on-surface synthesis12 to fabricate one-dimensional spin chains that contain the S = 1 polycyclic aromatic hydrocarbon triangulene as the building block. Using scanning tunnelling microscopy and spectroscopy at 4.5 K, we probe length-dependent magnetic excitations at the atomic scale in both open-ended and cyclic spin chains, and directly observe gapped spin excitations and fractional edge states therein. Exact diagonalization calculations provide conclusive evidence that the spin chains are described by the S = 1 bilinear-biquadratic Hamiltonian in the Haldane symmetry-protected topological phase. Our results open a bottom-up approach to study strongly correlated phases in purely organic materials, with the potential for the realization of measurement-based quantum computation13.
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Affiliation(s)
- Shantanu Mishra
- Empa-Swiss Federal Laboratories for Materials Science and Technology, Dübendorf, Switzerland.,IBM Research-Zurich, Rüschlikon, Switzerland
| | - Gonçalo Catarina
- International Iberian Nanotechnology Laboratory, Braga, Portugal.,University of Alicante, Sant Vicent del Raspeig, Spain
| | - Fupeng Wu
- Technical University of Dresden, Dresden, Germany
| | - Ricardo Ortiz
- University of Alicante, Sant Vicent del Raspeig, Spain
| | - David Jacob
- University of the Basque Country, San Sebastián, Spain.,IKERBASQUE, Basque Foundation for Science, Bilbao, Spain
| | - Kristjan Eimre
- Empa-Swiss Federal Laboratories for Materials Science and Technology, Dübendorf, Switzerland
| | - Ji Ma
- Technical University of Dresden, Dresden, Germany
| | - Carlo A Pignedoli
- Empa-Swiss Federal Laboratories for Materials Science and Technology, Dübendorf, Switzerland
| | - Xinliang Feng
- Technical University of Dresden, Dresden, Germany. .,Max Planck Institute of Microstructure Physics, Halle, Germany.
| | - Pascal Ruffieux
- Empa-Swiss Federal Laboratories for Materials Science and Technology, Dübendorf, Switzerland.
| | | | - Roman Fasel
- Empa-Swiss Federal Laboratories for Materials Science and Technology, Dübendorf, Switzerland.,University of Bern, Bern, Switzerland
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