Ferromagnetic Coupling of Mononuclear Fe Centers in a Self-Assembled Metal-Organic Network on Au(111)

Umbach, Tobias Reinhard; Bernien, Matthias; Hermanns, Christian Felix; Krüger, Alex; Sessi, Violetta; Fernández-Torrente, I.; Stoll, P.; Pascual, José; Franke, Katharina J.; Kuch, W.

doi:10.1103/physrevlett.109.267207

Cited by 64 publications

(69 citation statements)

References 34 publications

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“…33 Thus, on-surface coordination complexes provide a very important configurable material to tune spin-bearing layers employing on-surface magnetochemistry.…”

Section: The Journal Of Physical Chemistry Lettersmentioning

confidence: 99%

Emergence of On-Surface Magnetochemistry

Ballav

Wäckerlin

Siewert

et al. 2013

J. Phys. Chem. Lett.

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The control of exchange coupling across the molecule−substrate interface is a key feature in molecular spintronics. This Perspective reviews the emerging field of on-surface magnetochemistry, where coordination chemistry is applied to surface-supported metal porphyrins and metal phthalocyanines to control their magnetic properties. The particularities of the surface as a multiatomic ligand or "surface ligand" are introduced. The asymmetry involved in the action of a chemical ligand and a surface ligand on the same planar complexes modifies the well-established "trans effect" to the notion of the "surface-trans effect". As ad-complexes on ferromagnetic substrates are usually exchange-coupled, the magnetochemical implications of the surface-trans effect are of particular interest. The combined action of the different ligands allows for the reproducible control of spin states in on-surface supramolecular architectures and opens up new ways toward building and operating spin systems at interfaces. Notably, spin-switching has been demonstrated to be controlled collectively via the interaction with a ligand (chemical selectivity) and individually via local addressing at the interface.A century ago, Alfred Werner laid the foundation of modern coordination chemistry, an achievement for which he was awarded the Nobel Prize in Chemistry in 1913. The innovative concept of primary and secondary valences in coordination complexes that he introduced has since then developed into oxidation states and coordination numbers and become textbook knowledge for introductory chemistry. 1 Briefly, the transition-metal ion in a given coordination complex with a fixed oxidation state can be either diamagnetic or paramagnetic, depending on the number of the ligands as well as their nature. It is the ligands that are responsible for the splitting of the d orbitals of the metal ion into t 2g and e g levels, which are at the heart of ligand field theory (LFT). 1 Thereby, ligand coordination directly alters the magnetic properties. Among the existing coordination complexes, particularly spin-bearing four-coordinated square-planar porphyrins and phthalocyanines have received much attention during the last six decades. Here, the coordination number of the metal ion and hence its magnetic properties can be easily modified by coordination with external axial ligands leading to five/six-fold coordination complexes. 2 Recently, on-surface coordination chemistry of metal porphyrins and metal phthalocyanines has raised increasing attention. 3−5 In this field of research, coordination chemistry of the planar molecules is studied in the presence of a surface ligand and an optional axial ligand binding to the free on-top site. A central issue is whether the known gas-phase coordination chemistry concepts remain valid for ligand coordination of spin-bearing planar metal−organic molecules assembled on (magnetic) surfaces. Emerging evidence shows that due to the surface−molecule interaction, novel magnetochemical effects arise beyond those known...

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“…33 Thus, on-surface coordination complexes provide a very important configurable material to tune spin-bearing layers employing on-surface magnetochemistry.…”

Section: The Journal Of Physical Chemistry Lettersmentioning

confidence: 99%

Emergence of On-Surface Magnetochemistry

Ballav

Wäckerlin

Siewert

et al. 2013

J. Phys. Chem. Lett.

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“…In the light of these findings, we then perform calculations based on density functional theory (DFT) to establish the structure of the synthetic Fe-T4PT MOF supported on a Au(111) surface. 30 We show that the most stable structure consists of FeN 3 Au 3 units rather than on the expected FeN 6 building blocks. Beyond the interpretation of experimental results, a chemical modification of the ligand is proposed to generate a FeN 6 candidate for spin-crossover behavior.…”

mentioning

confidence: 99%

“…26 With this goal in mind, a promising route might come from the use of self-assembled metalorganic framework (MOF). 27 Indeed, magnetic couplings 28 were reported in several 2D MOF based on 3d ions such as Fe, 29,30 Ni, 31 Mn 32,33 or Cu. 34 Recently, Umbach et al have investigated a Au(111)-supported MOF based on Fe(II) ions and 2,4,6-tris(4-pyridyl)-1,3,5-triazine (T4PT) ligand.…”

mentioning

confidence: 99%

“…This picture is also supported by X-ray absorption spectroscopy (XAS) and X-ray magnetic circular dichroism (XMCD) measurements. 30 Around this cationic center, the top T4PT layer shows typical molecular levels with no hybridization either with the bottom organic layer or the metallic center. On the other hand, the bottom layer shows large hybridization with a modest charge transfer (0.28 e − ) to the lowest unoccupied molecular orbital 8 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 A c c e p t e d m a n u s c r i p t Page 9 of 15 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 A c c e p t e d m a n u s c r i p...…”

mentioning

confidence: 99%

“…34 Recently, Umbach et al have investigated a Au(111)-supported MOF based on Fe(II) ions and 2,4,6-tris(4-pyridyl)-1,3,5-triazine (T4PT) ligand. 30 Interestingly, in addition to the observation of a weakly ferromagnetic behaviour, the speculated structure of the system consists in FeN 6 units, an archetype arrangement of SCO systems. 35 In this letter, we use a model based on Fe(II) transiting unit to investigate the effect of dimensionality reduction and surface deposition.…”

mentioning

confidence: 99%

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Enhanced Cooperativity in Supported Spin-Crossover Metal–Organic Frameworks

Groizard

Papior

Guennic

et al. 2017

J. Phys. Chem. Lett.

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A c c e p t e d m a n u s c r i p t Molecular electronics originally proposed in the 1950s and reinvigorated by the founding proposition of Aviram and Ratner 1 has led to intense activity on the study of electronic transport through single molecules, supported by the advent of scanning tunneling microscopy (STM) and break junction setups. 2,3 More recently, molecules entered the field of spintronics, i.e. the control and manipulation of spins, 4 and gave birth to molecular spintronics, [5][6][7][8] where the working principle of the targeted devices relies on bistability. Molecular bistability has been best served by molecular magnetism with two distinct families: spin-crossover (SCO) compounds and single molecule magnets (SMM). 9,10 Whereas SMM display bistability at rather low temperatures, 9,10 higher temperature regimes are reached for SCO materials. 11 In order to bridge the gap between functional molecules and practical devices, one has to deposit the objects on a surface while retaining the bistability property. With respect to the intense activity in the field of adsorbed SMM, 8,[12][13][14][15] SCO supported compounds have received much less attention. It is only recently that supported examples have emerged, starting from 3-dimensional (3D) materials with thin-films grown on gold. 11,16,17 0D systems followed based on single SCO molecules, [18][19][20][21][22][23][24] or molecular junctions. 25 However, 2D monolayer organized networks exhibiting SCO behavior have not been reported so far. Not only should low-dimensional SCO patterns offer new insights into the spin transition phenomenon, but such organized networks may also offer the opportunity to control the intermolecular interactions dictating the collective behavior of transiting centers (a.k.a. cooperativity). 26 With this goal in mind, a promising route might come from the use of self-assembled metalorganic framework (MOF). 27 Indeed, magnetic couplings 28 were reported in several 2D MOF based on 3d ions such as Fe, 29,30 Ni, 31 Mn 32,33 or Cu. 34 Recently, Umbach et al. have investigated a Au(111)-supported MOF based on Fe(II) ions and 2,4,6-tris(4-pyridyl)-1,3,5-triazine (T4PT) ligand. 30 Interestingly, in addition to the observation of a weakly ferromagnetic behaviour, the speculated structure of the system consists in FeN 6 units, an archetype arrangement of SCO systems. 35 In this letter, we use a model based on Fe(II) transiting unit to investigate the effect of dimensionality reduction and surface deposition. Our thermodynamic model shows that a metallic A c c e p t e d m a n u s c r i p t substrate is likely to enhance cooperativity by an order of magnitude. In the light of these findings, we then perform calculations based on density functional theory (DFT) to establish the structure of the synthetic Fe-T4PT MOF supported on a Au(111) surface. 30 We show that the most stable structure consists of FeN 3 Au 3 units rather than on the expected FeN 6 building blocks. Beyond the interpretation of experimental results, a chemical mo...

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Complexity in Two‐Dimensional Assembly: Using Coordination Bonds

Lin¹,

Liu²

2021

Supramolecular Chemistry on Surfaces

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Ferromagnetic Coupling of Mononuclear Fe Centers in a Self-Assembled Metal-Organic Network on Au(111)

Cited by 64 publications

References 34 publications

Emergence of On-Surface Magnetochemistry

Emergence of On-Surface Magnetochemistry

Enhanced Cooperativity in Supported Spin-Crossover Metal–Organic Frameworks

Complexity in Two‐Dimensional Assembly: Using Coordination Bonds

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