1
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Johannsen S, Gruber M, Barreteau C, Seredyuk M, Antonio Real J, Markussen T, Berndt R. Spin-Crossover and Fragmentation of Fe(neoim) 2 on Silver and Gold. J Phys Chem Lett 2023; 14:7814-7823. [PMID: 37623823 DOI: 10.1021/acs.jpclett.3c01551] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 08/26/2023]
Abstract
The neutral spin crossover complex Fe(neoim)2, neoim being the deprotonated form of the ionogenic ligand 2-(1H-imidazol-2-yl)-9-methyl-1,10-phenanthroline (neoimH), is investigated on the (111) surfaces of Au and Ag using scanning tunneling microscopy and density functional theory calculations. The complex sublimates and adsorbs intact on Ag(111), where it exhibits an electron-induced spin crossover. However, it fragments on Au. According to density functional theory calculations, the adsorbed complex is drastically distorted by the interactions with the substrates, in particular by van der Waals forces. Dispersion interaction is also decisive for the relative stabilities of the low- and high-spin states of the adsorbed complex. The unexpected instability of the complex on the gold substrate is attributed to enhanced covalent bonding of the fragments to the substrate.
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Affiliation(s)
- Sven Johannsen
- Institut für Experimentelle und Angewandte Physik, Christian-Albrechts-Universität, 24098 Kiel, Germany
| | - Manuel Gruber
- Faculty of Physics and CENIDE, University of Duisburg-Essen, 47057 Duisburg, Germany
| | - Cyrille Barreteau
- Université Paris-Saclay CEA, CNRS SPEC, 91191 Gif-sur-Yvette, France
| | - Maksym Seredyuk
- Instituto de Ciencia Molecular (ICMol)/Departamento de Química Inorgánica, Universidad de Valencia, 46980 Paterna, Valencia, Spain
- Department of Chemistry, Taras Shevchenko National University of Kyiv, 64/13 Volodymyrska Street 01601 Kyiv, Ukraine
| | - José Antonio Real
- Instituto de Ciencia Molecular (ICMol)/Departamento de Química Inorgánica, Universidad de Valencia, 46980 Paterna, Valencia, Spain
| | | | - Richard Berndt
- Institut für Experimentelle und Angewandte Physik, Christian-Albrechts-Universität, 24098 Kiel, Germany
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2
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Grunwald J, Torres J, Buchholz A, Näther C, Kämmerer L, Gruber M, Rohlf S, Thakur S, Wende H, Plass W, Kuch W, Tuczek F. Defying the inverse energy gap law: a vacuum-evaporable Fe(ii) low-spin complex with a long-lived LIESST state. Chem Sci 2023; 14:7361-7380. [PMID: 37416721 PMCID: PMC10321519 DOI: 10.1039/d3sc00561e] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2023] [Accepted: 05/25/2023] [Indexed: 07/08/2023] Open
Abstract
The novel vacuum-evaporable complex [Fe(pypypyr)2] (pypypyr = bipyridyl pyrrolide) was synthesised and analysed as bulk material and as a thin film. In both cases, the compound is in its low-spin state up to temperatures of at least 510 K. Thus, it is conventionally considered a pure low-spin compound. According to the inverse energy gap law, the half time of the light-induced excited high-spin state of such compounds at temperatures approaching 0 K is expected to be in the regime of micro- or nanoseconds. In contrast to these expectations, the light-induced high-spin state of the title compound has a half time of several hours. We attribute this behaviour to a large structural difference between the two spin states along with four distinct distortion coordinates associated with the spin transition. This leads to a breakdown of single-mode behaviour and thus drastically decreases the relaxation rate of the metastable high-spin state. These unprecedented properties open up new strategies for the development of compounds showing light-induced excited spin state trapping (LIESST) at high temperatures, potentially around room temperature, which is relevant for applications in molecular spintronics, sensors, displays and the like.
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Affiliation(s)
- Jan Grunwald
- Institut für Anorganische Chemie, Christian-Albrechts-Universität zu Kiel 24098 Kiel Germany +49 431 880 1520 +49 431 880 1410
| | - Jorge Torres
- Institut für Experimentalphysik, Freie Universität Berlin Arnimallee 14 14195 Berlin Germany +49 30 838 452098 +49 30 838 52098
| | - Axel Buchholz
- Institut für Anorganische und Analytische Chemie, Friedrich-Schiller-Universität Jena 07743 Jena Germany
| | - Christian Näther
- Institut für Anorganische Chemie, Christian-Albrechts-Universität zu Kiel 24098 Kiel Germany +49 431 880 1520 +49 431 880 1410
| | - Lea Kämmerer
- Fakultät für Physik and CENIDE, Universität Duisburg-Essen 47048 Duisburg Germany
| | - Manuel Gruber
- Fakultät für Physik and CENIDE, Universität Duisburg-Essen 47048 Duisburg Germany
| | - Sebastian Rohlf
- Institut für Experimentelle und Angewandte Physik, Christian-Albrechts-Universität zu Kiel 24098 Kiel Germany
| | - Sangeeta Thakur
- Institut für Experimentalphysik, Freie Universität Berlin Arnimallee 14 14195 Berlin Germany +49 30 838 452098 +49 30 838 52098
| | - Heiko Wende
- Fakultät für Physik and CENIDE, Universität Duisburg-Essen 47048 Duisburg Germany
| | - Winfried Plass
- Institut für Anorganische und Analytische Chemie, Friedrich-Schiller-Universität Jena 07743 Jena Germany
| | - Wolfgang Kuch
- Institut für Experimentalphysik, Freie Universität Berlin Arnimallee 14 14195 Berlin Germany +49 30 838 452098 +49 30 838 52098
| | - Felix Tuczek
- Institut für Anorganische Chemie, Christian-Albrechts-Universität zu Kiel 24098 Kiel Germany +49 431 880 1520 +49 431 880 1410
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3
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Chen H, Yang HH, Frauhammer T, You H, Sun Q, Nagel P, Schuppler S, Gaspar AB, Real JA, Wulfhekel W. Observation of Exchange Interaction in Iron(II) Spin Crossover Molecules in Contact with Passivated Ferromagnetic Surface of Co/Au(111). SMALL (WEINHEIM AN DER BERGSTRASSE, GERMANY) 2023; 19:e2300251. [PMID: 36828799 DOI: 10.1002/smll.202300251] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/02/2023] [Indexed: 06/02/2023]
Abstract
Spin crossover (SCO) complexes sensitively react on changes of the environment by a change in the spin of the central metallic ion making them ideal candidates for molecular spintronics. In particular, the composite of SCO complexes and ferromagnetic (FM) surfaces would allow spin-state switching of the molecules in combination with the magnetic exchange interaction to the magnetic substrate. Unfortunately, when depositing SCO complexes on ferromagnetic surfaces, spin-state switching is blocked by the relatively strong interaction between the adsorbed molecules and the surface. Here, the Fe(II) SCO complex [FeII (Pyrz)2 ] (Pyrz = 3,5-dimethylpyrazolylborate) with sub-monolayer thickness in contact with a passivated FM film of Co on Au(111) is studied. In this case, the molecules preserve thermal spin crossover and at the same time the high-spin species show a sizable exchange interaction of > 0.9 T with the FM Co substrate. These observations provide a feasible design strategy in fabricating SCO-FM hybrid devices.
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Affiliation(s)
- Hongyan Chen
- Physikalisches Institut, Karlsruhe Institute of Technology (KIT), 76131, Karlsruhe, Germany
| | - Hung-Hsiang Yang
- Physikalisches Institut, Karlsruhe Institute of Technology (KIT), 76131, Karlsruhe, Germany
| | - Timo Frauhammer
- Physikalisches Institut, Karlsruhe Institute of Technology (KIT), 76131, Karlsruhe, Germany
| | - Haoran You
- Physikalisches Institut, Karlsruhe Institute of Technology (KIT), 76131, Karlsruhe, Germany
| | - Qing Sun
- Laboratory for Electron Microscopy, Karlsruhe Institute of Technology (KIT), 76131, Karlsruhe, Germany
| | - Peter Nagel
- Electron Spectroscopy Group, Institute for Quantum Materials and Technologies (IQMT), Karlsruhe Institute of Technology (KIT), 76021, Karlsruhe, Germany
- Karlsruhe Nano Micro Facility (KNMFi), Karlsruhe Institute of Technology (KIT), 76344, Eggenstein-Leopoldshafen, Germany
| | - Stefan Schuppler
- Electron Spectroscopy Group, Institute for Quantum Materials and Technologies (IQMT), Karlsruhe Institute of Technology (KIT), 76021, Karlsruhe, Germany
- Karlsruhe Nano Micro Facility (KNMFi), Karlsruhe Institute of Technology (KIT), 76344, Eggenstein-Leopoldshafen, Germany
| | - Ana Belén Gaspar
- Institut de Ciència Molecular (ICMol), Universitat de València, C/Catedrático José Beltrán Martínez 2, 46980, Paterna, Valencia, Spain
| | - José Antonio Real
- Institut de Ciència Molecular (ICMol), Universitat de València, C/Catedrático José Beltrán Martínez 2, 46980, Paterna, Valencia, Spain
| | - Wulf Wulfhekel
- Physikalisches Institut, Karlsruhe Institute of Technology (KIT), 76131, Karlsruhe, Germany
- Quantum Control Group, Institute for Quantum Materials and Technologies (IQMT), Karlsruhe Institute of Technology (KIT), 76021, Karlsruhe, Germany
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4
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Yazdani S, Phillips J, Ekanayaka TK, Cheng R, Dowben PA. The Influence of the Substrate on the Functionality of Spin Crossover Molecular Materials. Molecules 2023; 28:molecules28093735. [PMID: 37175145 PMCID: PMC10180229 DOI: 10.3390/molecules28093735] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2023] [Revised: 04/18/2023] [Accepted: 04/18/2023] [Indexed: 05/15/2023] Open
Abstract
Spin crossover complexes are a route toward designing molecular devices with a facile readout due to the change in conductance that accompanies the change in spin state. Because substrate effects are important for any molecular device, there are increased efforts to characterize the influence of the substrate on the spin state transition. Several classes of spin crossover molecules deposited on different types of surface, including metallic and non-metallic substrates, are comprehensively reviewed here. While some non-metallic substrates like graphite seem to be promising from experimental measurements, theoretical and experimental studies indicate that 2D semiconductor surfaces will have minimum interaction with spin crossover molecules. Most metallic substrates, such as Au and Cu, tend to suppress changes in spin state and affect the spin state switching process due to the interaction at the molecule-substrate interface that lock spin crossover molecules in a particular spin state or mixed spin state. Of course, the influence of the substrate on a spin crossover thin film depends on the molecular film thickness and perhaps the method used to deposit the molecular film.
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Affiliation(s)
- Saeed Yazdani
- Department of Physics, Indiana University-Purdue University Indianapolis, Indianapolis, IN 46202, USA
| | - Jared Phillips
- Department of Physics, Indiana University-Purdue University Indianapolis, Indianapolis, IN 46202, USA
| | - Thilini K Ekanayaka
- Department of Physics and Astronomy, Jorgensen Hall, University of Nebraska, Lincoln, NE 68588-0299, USA
| | - Ruihua Cheng
- Department of Physics, Indiana University-Purdue University Indianapolis, Indianapolis, IN 46202, USA
| | - Peter A Dowben
- Department of Physics and Astronomy, Jorgensen Hall, University of Nebraska, Lincoln, NE 68588-0299, USA
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5
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Kelai M, Tauzin A, Railean A, Repain V, Lagoute J, Girard Y, Rousset S, Otero E, Mallah T, Boillot ML, Enachescu C, Bellec A. Interface versus Bulk Light-Induced Switching in Spin-Crossover Molecular Ultrathin Films Adsorbed on a Metallic Surface. J Phys Chem Lett 2023; 14:1949-1954. [PMID: 36787373 DOI: 10.1021/acs.jpclett.2c03733] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/18/2023]
Abstract
Spin-crossover molecules present the unique property of having two spin states that can be controlled by light excitation at low temperature. Here, we report on the photoexcitation of [FeII((3, 5-(CH3)2Pz)3BH)2] (Pz = pyrazolyl) ultrathin films, with thicknesses ranging from 0.9 to 5.3 monolayers, adsorbed on Cu(111) substrate. Using X-ray absorption spectroscopy measurements, we confirm the anomalous light-induced spin-state switching observed for sub-monolayer coverage and demonstrate that it is confined to the first molecular layer in contact with the metallic substrate. For higher coverages, the well-known light-induced excited spin-state trapping effect is recovered. Combining continuous light excitation with thermal cycling, we demonstrate that at low temperature light-induced thermal hysteresis is measured for the thicker films, while for sub-monolayer coverage, the light enables extension of the thermal conversion over a large temperature range. Mechanoelastic simulations underline that, due to the intermolecular interactions, opposite behaviors are observed in the different layers composing the films.
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Affiliation(s)
- Massine Kelai
- Université Paris Cité, CNRS, Laboratoire Matériaux et Phénomènes Quantiques, F-75013 Paris, France
| | - Arthur Tauzin
- Université Paris-Saclay, Institut de Chimie Moléculaire et des Matériaux d'Orsay, CNRS, UMR 8182, 91400 Orsay, France
| | - Anastasia Railean
- Faculty of Physics, Alexandru Ioan Cuza University of Iasi, Iasi 700506, Romania
| | - Vincent Repain
- Université Paris Cité, CNRS, Laboratoire Matériaux et Phénomènes Quantiques, F-75013 Paris, France
| | - Jérôme Lagoute
- Université Paris Cité, CNRS, Laboratoire Matériaux et Phénomènes Quantiques, F-75013 Paris, France
| | - Yann Girard
- Université Paris Cité, CNRS, Laboratoire Matériaux et Phénomènes Quantiques, F-75013 Paris, France
| | - Sylvie Rousset
- Université Paris Cité, CNRS, Laboratoire Matériaux et Phénomènes Quantiques, F-75013 Paris, France
| | - Edwige Otero
- Synchrotron SOLEIL, L'Orme des Merisiers, Saint-Aubin, 91192 Gif sur Yvette, France
| | - Talal Mallah
- Université Paris-Saclay, Institut de Chimie Moléculaire et des Matériaux d'Orsay, CNRS, UMR 8182, 91400 Orsay, France
| | - Marie-Laure Boillot
- Université Paris-Saclay, Institut de Chimie Moléculaire et des Matériaux d'Orsay, CNRS, UMR 8182, 91400 Orsay, France
| | - Cristian Enachescu
- Faculty of Physics, Alexandru Ioan Cuza University of Iasi, Iasi 700506, Romania
| | - Amandine Bellec
- Université Paris Cité, CNRS, Laboratoire Matériaux et Phénomènes Quantiques, F-75013 Paris, France
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6
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Montenegro-Pohlhammer N, Palomino CM, Calzado CJ. Exploring the potential as molecular quantum-dot cellular automata of a mixed-valence Ru2 complex deposited on a Au(111) surface. Inorg Chem Front 2023. [DOI: 10.1039/d2qi02647c] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/05/2023]
Abstract
A Ru2+ complex deposited on a Au(111) surface in the presence of a counterion presents excess charge localized on one side of the molecule. The switching can be promoted by an applied electric field, E, stronger than the critical field strength Ec.
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Affiliation(s)
- Nicolás Montenegro-Pohlhammer
- Laboratory of Theoretical Chemistry, Faculty of Chemistry and Biology, University of Santiago de Chile (USACH), 9170022, Santiago, Chile
| | - Carlos M. Palomino
- Departamento de Química Física, Universidad de Sevilla, c/ Prof. García González, s/n 41012, Sevilla, Spain
| | - Carmen J. Calzado
- Departamento de Química Física, Universidad de Sevilla, c/ Prof. García González, s/n 41012, Sevilla, Spain
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7
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Ndiaye M, Boukheddaden K. Pressure-induced multi-step and self-organized spin states in an electro-elastic model for spin-crossover solids. Phys Chem Chem Phys 2022; 24:12870-12889. [PMID: 35583047 DOI: 10.1039/d2cp01285e] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Spin transition materials are known to exhibit a rich variety of behaviors under several stimuli, among which pressure leads to major changes in their electronic and elastic properties. From an experimental point of view, thermal spin transitions under isotropic pressure showed transformations from (i) hysteretic to continuous transformations where the hysteresis width vanishes beyond some threshold pressure value; this is the conventional case. In several other cases very pathological and unexpected behaviours emerged, like (ii) persistent hysteresis under pressure; (iii) non-uniform behavior of the thermal hysteresis width which first increases with pressure and then decreases and vanishes at higher pressures; (iv) furthermore, double step transitions induced by pressure are also often obtained, where the pressure triggers the appearance of a plateau during the thermal transition, leading to two-step transitions, and finally (v) other non-conventional re-entrant transitions, where the thermal hysteresis vanishes at some pressure and then reappears at higher pressure values are also observed. In the present theoretical study, we investigate this problem with an electro-elastic description of the spin-crossover phenomenon by solving the Hamiltonian using a Monte Carlo technique. The pressure effect is here introduced directly in the lattice parameters, the elastic constants and ligand field energy. By considering spin state-dependent compressibility, we demonstrate that a large panel of experimental observations can be qualitatively described with this model. Among them, we quote (i) the conventional pressure effect decreasing the hysteresis width, (ii) the unconventional cases with pressure causing a non-monotonous behavior of the hysteresis width, (iii) re-entrant, as well as (iv) double step transitions accompanied with various types of spin state self-organization in the plateau regions.
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Affiliation(s)
- Mamadou Ndiaye
- Université Paris-Saclay, UVSQ, CNRS, GEMaC, 45 Avenue des Etats Unis, 78035 Versailles, France. .,Département de Physique, Université Cheikh Anta Diop de Dakar, FST, BP 5005, Fann, Dakar, Senegal
| | - Kamel Boukheddaden
- Université Paris-Saclay, UVSQ, CNRS, GEMaC, 45 Avenue des Etats Unis, 78035 Versailles, France.
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8
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Johannsen S, Ossinger S, Grunwald J, Herman A, Wende H, Tuczek F, Gruber M, Berndt R. Spin Crossover in a Cobalt Complex on Ag(111). Angew Chem Int Ed Engl 2022; 61:e202115892. [PMID: 35032345 PMCID: PMC9303790 DOI: 10.1002/anie.202115892] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2021] [Indexed: 12/05/2022]
Abstract
The Co‐based complex [Co(H2B(pz)(pypz))2] (py=pyridine, pz=pyrazole) deposited on Ag(111) was investigated with scanning tunneling microscopy at ≈5 K. Due to a bis(tridentate) coordination sphere the molecules aggregate mainly into tetramers. Individual complexes in these tetramers undergo reversible transitions between two states with characteristic image contrasts when current is passed through them or one of their neighbors. Two molecules exhibit this bistability while the other two molecules are stable. The transition rates vary linearly with the tunneling current and exhibit an intriguing dependence on the bias voltage and its polarity. We interpret the states as being due to S=1/2 and 3/2 spin states of the Co2+ complex. The image contrast and the orders‐of‐magnitude variations of the switching yields can be tentatively understood from the calculated orbital structures of the two spin states, thus providing first insights into the mechanism of electron‐induced excited spin‐state trapping (ELIESST).
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Affiliation(s)
- Sven Johannsen
- Institut für Experimentelle und Angewandte Physik, Christian-Albrechts-Universität, 24098, Kiel, Germany
| | - Sascha Ossinger
- Institut für Anorganische Chemie, Christian-Albrechts-Universität, 24098, Kiel, Germany.,Department of Chemistry, University of Basel, St. Johanns-Ring 19, 4056, Basel, Switzerland
| | - Jan Grunwald
- Institut für Anorganische Chemie, Christian-Albrechts-Universität, 24098, Kiel, Germany
| | - Alexander Herman
- Faculty of Physics and CENIDE, University of Duisburg-Essen, 47057, Duisburg, Germany
| | - Heiko Wende
- Faculty of Physics and CENIDE, University of Duisburg-Essen, 47057, Duisburg, Germany
| | - Felix Tuczek
- Institut für Anorganische Chemie, Christian-Albrechts-Universität, 24098, Kiel, Germany
| | - Manuel Gruber
- Institut für Experimentelle und Angewandte Physik, Christian-Albrechts-Universität, 24098, Kiel, Germany.,Faculty of Physics and CENIDE, University of Duisburg-Essen, 47057, Duisburg, Germany
| | - Richard Berndt
- Institut für Experimentelle und Angewandte Physik, Christian-Albrechts-Universität, 24098, Kiel, Germany
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9
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Johannsen S, Ossinger S, Grunwald J, Herman A, Wende H, Tuczek F, Gruber M, Berndt R. Spin Crossover in a Cobalt Complex on Ag(111). Angew Chem Int Ed Engl 2022. [DOI: 10.1002/ange.202115892] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Affiliation(s)
- Sven Johannsen
- Institut für Experimentelle und Angewandte Physik Christian-Albrechts-Universität 24098 Kiel Germany
| | - Sascha Ossinger
- Institut für Anorganische Chemie Christian-Albrechts-Universität 24098 Kiel Germany
- Department of Chemistry University of Basel St. Johanns-Ring 19 4056 Basel Switzerland
| | - Jan Grunwald
- Institut für Anorganische Chemie Christian-Albrechts-Universität 24098 Kiel Germany
| | - Alexander Herman
- Faculty of Physics and CENIDE University of Duisburg-Essen 47057 Duisburg Germany
| | - Heiko Wende
- Faculty of Physics and CENIDE University of Duisburg-Essen 47057 Duisburg Germany
| | - Felix Tuczek
- Institut für Anorganische Chemie Christian-Albrechts-Universität 24098 Kiel Germany
| | - Manuel Gruber
- Institut für Experimentelle und Angewandte Physik Christian-Albrechts-Universität 24098 Kiel Germany
- Faculty of Physics and CENIDE University of Duisburg-Essen 47057 Duisburg Germany
| | - Richard Berndt
- Institut für Experimentelle und Angewandte Physik Christian-Albrechts-Universität 24098 Kiel Germany
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10
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Sánchez-de-Armas R, Calzado CJ. Spin-crossover Fe(ii) complexes on a surface: a mixture of low-spin and high-spin molecules at low temperature from quantum-chemistry calculations. Inorg Chem Front 2022. [DOI: 10.1039/d1qi01487k] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The deposition of a 2D monolayer of an Fe(ii) SCO complex on Au(111) is studied by quantum chemistry calculations. The results indicate that there exists thermodynamic and kinetic factors favoring the presence of the mixed HS/LS state at low temperature.
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Affiliation(s)
- Rocío Sánchez-de-Armas
- Departamento de Química Física, Universidad de Sevilla, calle Prof. García González, s/n, 41012 Sevilla, Spain
| | - Carmen J. Calzado
- Departamento de Química Física, Universidad de Sevilla, calle Prof. García González, s/n, 41012 Sevilla, Spain
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11
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Tong Y, Kelaï M, Bairagi K, Repain V, Lagoute J, Girard Y, Rousset S, Boillot ML, Mallah T, Enachescu C, Bellec A. Voltage-Induced Bistability of Single Spin-Crossover Molecules in a Two-Dimensional Monolayer. J Phys Chem Lett 2021; 12:11029-11034. [PMID: 34743521 DOI: 10.1021/acs.jpclett.1c03271] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
Bistable spin-crossover molecules are particularly interesting for the development of innovative electronic and spintronic devices as they present two spin states that can be controlled by external stimuli. In this paper, we report the voltage-induced switching of the high spin/low spin electronic states of spin-crossover molecules self-assembled in dense 2D networks on Au(111) and Cu(111) by scanning tunneling microscopy at low temperature. On Au(111), voltage pulses lead to the nonlocal switching of the molecules from any─high or low─spin state to the other followed by a spontaneous relaxation toward their initial state within minutes. On the other hand, on Cu(111), single molecules can be addressed at will. They retain their new electronic configuration after a voltage pulse. The memory effect demonstrated on Cu(111) is due to an interplay between long-range intermolecular interaction and molecule/substrate coupling as confirmed by mechanoelastic simulations.
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Affiliation(s)
- Yongfeng Tong
- Université de Paris, Laboratoire Matériaux et Phénomènes Quantiques (MPQ), CNRS-UMR7162, 75013, Paris, France
| | - Massine Kelaï
- Université de Paris, Laboratoire Matériaux et Phénomènes Quantiques (MPQ), CNRS-UMR7162, 75013, Paris, France
| | - Kaushik Bairagi
- Université de Paris, Laboratoire Matériaux et Phénomènes Quantiques (MPQ), CNRS-UMR7162, 75013, Paris, France
| | - Vincent Repain
- Université de Paris, Laboratoire Matériaux et Phénomènes Quantiques (MPQ), CNRS-UMR7162, 75013, Paris, France
| | - Jérôme Lagoute
- Université de Paris, Laboratoire Matériaux et Phénomènes Quantiques (MPQ), CNRS-UMR7162, 75013, Paris, France
| | - Yann Girard
- Université de Paris, Laboratoire Matériaux et Phénomènes Quantiques (MPQ), CNRS-UMR7162, 75013, Paris, France
| | - Sylvie Rousset
- Université de Paris, Laboratoire Matériaux et Phénomènes Quantiques (MPQ), CNRS-UMR7162, 75013, Paris, France
| | - Marie-Laure Boillot
- Institut de Chimie Moléculaire et des Matériaux d'Orsay, Université Paris-Saclay, CNRS, UMR 8182, 91405 Orsay Cedex, France
| | - Talal Mallah
- Institut de Chimie Moléculaire et des Matériaux d'Orsay, Université Paris-Saclay, CNRS, UMR 8182, 91405 Orsay Cedex, France
| | - Cristian Enachescu
- Faculty of Physics, Alexandru Ioan Cuza University of Iasi, Iasi 700506, Romania
| | - Amandine Bellec
- Université de Paris, Laboratoire Matériaux et Phénomènes Quantiques (MPQ), CNRS-UMR7162, 75013, Paris, France
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12
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Zhang Y. Fe(phen) 2(NCS) 2 on Al(100): influence of AlN layer on spin crossover barrier. Phys Chem Chem Phys 2021; 23:23758-23767. [PMID: 34643204 DOI: 10.1039/d1cp03782j] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
We study how a nitride layer affects spin crossover (SCO) in a single Fe(phen)2(NCS)2 (Fephen) molecule adsorbed on the Al(100) surface using ab initio calculations. The Coulomb correlation of the open-shell 3d electrons has been considered using a Hubbard-U correction within different exchange-correlation approximations, including the van der Waals density functional. We determine the SCO energy barrier by computing the minimum energy path between the high-spin (HS) and low-spin (LS) states via direct constraint relaxations. It is shown that the HS-LS energy difference is slightly increased once deposited on Al(100), and thus LS states tend to be stabilized, as usually observed on metallic substrates. The oxidation of metallic Al to aluminum ions in the AlN layer promotes molecular adsorption, while it decreases HS-LS splitting, making Fephen switchable between its two spin states. Due to enhanced molecule-substrate bonding, the SCO barrier height is considerably increased, which may promote cooperativity. This effect is consistent with the AlN facilitated charge transfer at the interface that results from a reduction in surface work function. Our findings reveal the crucial role that surface electronic structure plays in maintaining spin bistability of the molecular adsorbate.
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Affiliation(s)
- Yachao Zhang
- Guizhou Provincial Key Laboratory of Computational Nano-Material Science, Guizhou Education University, Guiyang 550018, China.
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13
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Johannsen S, Ossinger S, Markussen T, Tuczek F, Gruber M, Berndt R. Electron-Induced Spin-Crossover in Self-Assembled Tetramers. ACS NANO 2021; 15:11770-11778. [PMID: 34133115 DOI: 10.1021/acsnano.1c02698] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
The spin crossover compound Fe(H2B(pyrazole)(pyridylpyrazole))2 was investigated in detail on Ag(111) with scanning tunneling microscopy (STM). A large fraction of the deposited molecules condenses into gridlike tetramers. Two molecules of each tetramer may be converted between two states by current injection. We attribute this effect to a spin transition. This interpretation is supported by control experiments on the analogous, magnetically passive Zn compound that forms virtually identical tetramers but exhibits no switching. The switching yields were studied for various electron energies, and the resulting values exceed those reported from other SCO systems by 2 orders of magnitude. The other two molecules of a tetramer were immutable. However, they may be used as contacts for current injection that leads to conversion of one of their neighbors. This "remote" switching is fairly efficient with yields reduced by only one to two orders of magnitude compared to direct excitation of a switchable molecule. We present a model of the tetramer structure that reproduces key observations from the experiments. In particular, sterical blocking prevents spin crossover of two molecules of a tetramer. Density functional theory calculations show that the model indeed represents a minimum energy structure. They also reproduce STM images and corroborate a remote-switching mechanism that is based on electron transfer between molecules.
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Affiliation(s)
- Sven Johannsen
- Institut für Experimentelle und Angewandte Physik, Christian-Albrechts-Universität, 24098 Kiel, Germany
| | - Sascha Ossinger
- Institut für Anorganische Chemie, Christian-Albrechts-Universität, 24098 Kiel, Germany
| | - Troels Markussen
- Synopsys Denmark, Fruebjergvej 3, Postbox 4, DK-2100 Copenhagen, Denmark
| | - Felix Tuczek
- Institut für Anorganische Chemie, Christian-Albrechts-Universität, 24098 Kiel, Germany
| | - Manuel Gruber
- Institut für Experimentelle und Angewandte Physik, Christian-Albrechts-Universität, 24098 Kiel, Germany
- Faculty of Physics, University of Duisburg-Essen, 47057 Duisburg, Germany
| | - Richard Berndt
- Institut für Experimentelle und Angewandte Physik, Christian-Albrechts-Universität, 24098 Kiel, Germany
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14
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Kelai M, Repain V, Tauzin A, Li W, Girard Y, Lagoute J, Rousset S, Otero E, Sainctavit P, Arrio MA, Boillot ML, Mallah T, Enachescu C, Bellec A. Thermal Bistability of an Ultrathin Film of Iron(II) Spin-Crossover Molecules Directly Adsorbed on a Metal Surface. J Phys Chem Lett 2021; 12:6152-6158. [PMID: 34184899 DOI: 10.1021/acs.jpclett.1c01366] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
Spin-crossover molecules are very attractive compounds to realize multifunctional spintronic devices. Understanding their properties when deposited on metals is therefore crucial for their future rational implementation as ultrathin films in such devices. Using X-ray absorption spectroscopy, we study the thermal transition of the spin-crossover compound FeII((3,5-(CH3)2Pz)3BH)2 from submonolayer to multilayers on a Cu(111) substrate. We determine how the residual fraction of high spin molecules at low temperature, as well as the bistability range and the temperature of switching, depends on the layer thickness. The most spectacular effect is the clear opening of a 35 ± 9 K thermal hysteresis loop for a 3.0 ± 0.7 monolayers thick film. To better understand the role played by the substrate and the dimensionality on the thermal bistability, we have performed Monte Carlo Arrhenius simulations in the framework of a mechanoelastic model that include a molecule-substrate interaction. This model reproduces well the main features observed experimentally and can predict how the spin-crossover transition is modified by the thickness and the substrate interaction.
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Affiliation(s)
- Massine Kelai
- Matériaux et Phénomènes Quantiques, Université de Paris, CNRS UMR 7162, 75013 Paris, France
| | - Vincent Repain
- Matériaux et Phénomènes Quantiques, Université de Paris, CNRS UMR 7162, 75013 Paris, France
| | - Arthur Tauzin
- Institut de Chimie Moléculaire et des Matériaux d'Orsay, Univ Paris Sud, Université Paris-Saclay, CNRS, UMR 8182, 91405 Orsay Cedex, France
| | - Weibin Li
- Institut de Minéralogie, de Physique des Matériaux et de Cosmochimie, CNRS UMR7590, Sorbonne Université, MNHN, 75252 Paris Cedex 5, France
| | - Yann Girard
- Matériaux et Phénomènes Quantiques, Université de Paris, CNRS UMR 7162, 75013 Paris, France
| | - Jérôme Lagoute
- Matériaux et Phénomènes Quantiques, Université de Paris, CNRS UMR 7162, 75013 Paris, France
| | - Sylvie Rousset
- Matériaux et Phénomènes Quantiques, Université de Paris, CNRS UMR 7162, 75013 Paris, France
| | - Edwige Otero
- Synchrotron SOLEIL, L'Orme des Merisiers, Saint-Aubin, 91192 Gif sur Yvette, France
| | - Philippe Sainctavit
- Institut de Minéralogie, de Physique des Matériaux et de Cosmochimie, CNRS UMR7590, Sorbonne Université, MNHN, 75252 Paris Cedex 5, France
- Synchrotron SOLEIL, L'Orme des Merisiers, Saint-Aubin, 91192 Gif sur Yvette, France
| | - Marie-Anne Arrio
- Institut de Minéralogie, de Physique des Matériaux et de Cosmochimie, CNRS UMR7590, Sorbonne Université, MNHN, 75252 Paris Cedex 5, France
| | - Marie-Laure Boillot
- Institut de Chimie Moléculaire et des Matériaux d'Orsay, Univ Paris Sud, Université Paris-Saclay, CNRS, UMR 8182, 91405 Orsay Cedex, France
| | - Talal Mallah
- Institut de Chimie Moléculaire et des Matériaux d'Orsay, Univ Paris Sud, Université Paris-Saclay, CNRS, UMR 8182, 91405 Orsay Cedex, France
| | - Cristian Enachescu
- Faculty of Physics, Alexandru Ioan Cuza University of Iasi, Iasi, 700506, Romania
| | - Amandine Bellec
- Matériaux et Phénomènes Quantiques, Université de Paris, CNRS UMR 7162, 75013 Paris, France
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15
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Kipgen L, Bernien M, Tuczek F, Kuch W. Spin-Crossover Molecules on Surfaces: From Isolated Molecules to Ultrathin Films. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2021; 33:e2008141. [PMID: 33963619 DOI: 10.1002/adma.202008141] [Citation(s) in RCA: 30] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/02/2020] [Revised: 01/22/2021] [Indexed: 06/12/2023]
Abstract
Molecular spintronics seeks to use single or few molecules as functional building blocks for spintronic applications, directly relying on molecular properties or properties of interfaces between molecules and inorganic electrodes. Spin-crossover molecules (SCMs) are one of the most promising classes of candidates for molecular spintronics due to their bistability deriving from the existence of two spin states that can be reversibly switched by temperature, light, electric fields, etc. Building devices based on single or few molecules would entail connecting the molecule(s) with solid surfaces and understanding the fundamental behavior of the resulting assemblies. Herein, the investigations of SCMs on solid surfaces, ranging from isolated single molecules (submonolayers) to ultrathin films (mainly in the sub-10 nm range) are summarized. The achievements, challenges and prospects in this field are highlighted.
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Affiliation(s)
- Lalminthang Kipgen
- Institut für Experimentalphysik, Freie Universität Berlin, Arnimallee 14, 14195, Berlin, Germany
| | - Matthias Bernien
- Institut für Experimentalphysik, Freie Universität Berlin, Arnimallee 14, 14195, Berlin, Germany
| | - Felix Tuczek
- Institut für Anorganische Chemie, Christian-Albrechts-Universität zu Kiel, Max-Eyth-Straße 2, 24118, Kiel, Germany
| | - Wolfgang Kuch
- Institut für Experimentalphysik, Freie Universität Berlin, Arnimallee 14, 14195, Berlin, Germany
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16
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Nonvolatile Voltage Controlled Molecular Spin-State Switching for Memory Applications. MAGNETOCHEMISTRY 2021. [DOI: 10.3390/magnetochemistry7030037] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
Abstract
Nonvolatile, molecular multiferroic devices have now been demonstrated, but it is worth giving some consideration to the issue of whether such devices could be a competitive alternative for solid-state nonvolatile memory. For the Fe (II) spin crossover complex [Fe{H2B(pz)2}2(bipy)], where pz = tris(pyrazol-1-yl)-borohydride and bipy = 2,2′-bipyridine, voltage-controlled isothermal changes in the electronic structure and spin state have been demonstrated and are accompanied by changes in conductance. Higher conductance is seen with [Fe{H2B(pz)2}2(bipy)] in the high spin state, while lower conductance occurs for the low spin state. Plausibly, there is the potential here for low-cost molecular solid-state memory because the essential molecular thin films are easily fabricated. However, successful device fabrication does not mean a device that has a practical value. Here, we discuss the progress and challenges yet facing the fabrication of molecular multiferroic devices, which could be considered competitive to silicon.
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17
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Palomino CM, Sánchez-de-Armas R, Calzado CJ. Theoretical inspection of the spin-crossover [Fe(tzpy) 2(NCS) 2] complex on Au(100) surface. J Chem Phys 2021; 154:034701. [PMID: 33499621 DOI: 10.1063/5.0036612] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
We explore the deposition of the spin-crossover [Fe(tzpy)2(NCS)2] complex on the Au(100) surface by means of density functional theory (DFT) based calculations. Two different routes have been employed: low-cost finite cluster-based calculations, where both the Fe complex and the surface are maintained fixed while the molecule approaches the surface; and periodic DFT plane-wave calculations, where the surface is represented by a four-layer slab and both the molecule and surface are relaxed. Our results show that the bridge adsorption site is preferred over the on-top and fourfold hollow ones for both spin states, although they are energetically close. The LS molecule is stabilized by the surface, and the HS-LS energy difference is enhanced by about 15%-25% once deposited. The different Fe ligand field for LS and HS molecules manifests on the composition and energy of the low-lying bands. Our simulated STM images indicate that it is possible to distinguish the spin state of the deposited molecules by tuning the bias voltage of the STM tip. Finally, it should be noted that the use of a reduced size cluster to simulate the Au(100) surface proves to be a low-cost and reliable strategy, providing results in good agreement with those resulting from state-of-the-art periodic calculations for this system.
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Affiliation(s)
- Carlos M Palomino
- Departamento de Química Física, c/Profesor García González, s/n 41012 Sevilla, Spain
| | | | - Carmen J Calzado
- Departamento de Química Física, c/Profesor García González, s/n 41012 Sevilla, Spain
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18
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Kelai M, Cahier B, Atanasov M, Neese F, Tong Y, Zhang L, Bellec A, Iasco O, Rivière E, Guillot R, Chacon C, Girard Y, Lagoute J, Rousset S, Repain V, Otero E, Arrio MA, Sainctavit P, Barra AL, Boillot ML, Mallah T. Robust magnetic anisotropy of a monolayer of hexacoordinate Fe( ii) complexes assembled on Cu(111). Inorg Chem Front 2021. [DOI: 10.1039/d1qi00085c] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The tris pyrazolyl borate ligand imposes a rigid scaffold around Fe(ii) ensuring a robust magnetic anisotropy when the molecules assembled as monolayers suffer from the dissymmetric environment of the substrate/vacuum interface.
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19
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Montenegro‐Pohlhammer N, Sánchez‐de‐Armas R, Calzado CJ. Deposition of the Spin Crossover Fe
II
–Pyrazolylborate Complex on Au(111) Surface at the Molecular Level. Chemistry 2020; 27:712-723. [DOI: 10.1002/chem.202003520] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2020] [Revised: 08/21/2020] [Indexed: 01/01/2023]
Affiliation(s)
| | - Rocío Sánchez‐de‐Armas
- Departamento de Química Física Universidad de Sevilla, c/ Profesor García González, s/n. 41012 Sevilla Spain
| | - Carmen J. Calzado
- Departamento de Química Física Universidad de Sevilla, c/ Profesor García González, s/n. 41012 Sevilla Spain
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20
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Zhang Y. Surface effects on temperature-driven spin crossover in Fe(phen) 2(NCS) 2. J Chem Phys 2020; 153:134704. [DOI: 10.1063/5.0027641] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Affiliation(s)
- Yachao Zhang
- Guizhou Provincial Key Laboratory of Computational Nano-Material Science, Guizhou Education University, Guiyang 550018, China
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21
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Abstract
The transfer of the inherent bistability of spin crossover compounds to surfaces has attracted considerable interest in recent years. The deposition of the complexes on surfaces allows investigating them individually and to further understand the microscopic mechanisms at play. Moreover, it offers the prospect of engineering switchable functional surfaces. We review recent progress in the field with a particular focus on the challenges and limits associated with the dominant experimental techniques used, namely near-edge X-ray absorption fine structure (NEXAFS) spectroscopy and scanning tunneling microscopy (STM). One of the main difficulties in NEXAFS-based experiments is to ascertain that the complexes are in direct contact with the surfaces. We show that molecular coverage determination based on the amplitude of the edge-jump of interest is challenging because the latter quantity depends on the substrate. Furthermore, NEXAFS averages the signals of a large number of molecules, which may be in different states. In particular, we highlight that the signal of fragmented molecules is difficult to distinguish from that of intact and functional ones. In contrast, STM allows investigating individual complexes, but the identification of the spin states is at best done indirectly. As quite some of the limits of the techniques are becoming apparent as the field is gaining maturity, their detailed descriptions will be useful for future investigations and for taking a fresh look at earlier reports.
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22
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Zhang L, Tong Y, Kelai M, Bellec A, Lagoute J, Chacon C, Girard Y, Rousset S, Boillot M, Rivière E, Mallah T, Otero E, Arrio M, Sainctavit P, Repain V. Anomalous Light‐Induced Spin‐State Switching for Iron(II) Spin‐Crossover Molecules in Direct Contact with Metal Surfaces. Angew Chem Int Ed Engl 2020. [DOI: 10.1002/ange.202003896] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Affiliation(s)
- Luqiong Zhang
- Institut de Minéralogie, de Physique des Matériaux et, de Cosmochimie, CNRS UMR7590 Sorbonne Université, MNHN 75252 Paris Cedex 5 France
| | - Yongfeng Tong
- Université de Paris Laboratoire Matériaux et Phénomènes Quantiques, CNRS 75013 Paris France
| | - Massine Kelai
- Université de Paris Laboratoire Matériaux et Phénomènes Quantiques, CNRS 75013 Paris France
| | - Amandine Bellec
- Université de Paris Laboratoire Matériaux et Phénomènes Quantiques, CNRS 75013 Paris France
| | - Jérôme Lagoute
- Université de Paris Laboratoire Matériaux et Phénomènes Quantiques, CNRS 75013 Paris France
| | - Cyril Chacon
- Université de Paris Laboratoire Matériaux et Phénomènes Quantiques, CNRS 75013 Paris France
| | - Yann Girard
- Université de Paris Laboratoire Matériaux et Phénomènes Quantiques, CNRS 75013 Paris France
| | - Sylvie Rousset
- Université de Paris Laboratoire Matériaux et Phénomènes Quantiques, CNRS 75013 Paris France
| | - Marie‐Laure Boillot
- Institut de Chimie Moléculaire et des Matériaux d'Orsay Univ Paris Sud Université Paris-Saclay CNRS, UMR 8182 91405 Orsay Cedex France
| | - Eric Rivière
- Institut de Chimie Moléculaire et des Matériaux d'Orsay Univ Paris Sud Université Paris-Saclay CNRS, UMR 8182 91405 Orsay Cedex France
| | - Talal Mallah
- Institut de Chimie Moléculaire et des Matériaux d'Orsay Univ Paris Sud Université Paris-Saclay CNRS, UMR 8182 91405 Orsay Cedex France
| | - Edwige Otero
- Synchrotron SOLEIL L'Orme des Merisiers Saint-Aubin 91192 Gif sur Yvette France
| | - Marie‐Anne Arrio
- Institut de Minéralogie, de Physique des Matériaux et, de Cosmochimie, CNRS UMR7590 Sorbonne Université, MNHN 75252 Paris Cedex 5 France
| | - Philippe Sainctavit
- Institut de Minéralogie, de Physique des Matériaux et, de Cosmochimie, CNRS UMR7590 Sorbonne Université, MNHN 75252 Paris Cedex 5 France
- Synchrotron SOLEIL L'Orme des Merisiers Saint-Aubin 91192 Gif sur Yvette France
| | - Vincent Repain
- Université de Paris Laboratoire Matériaux et Phénomènes Quantiques, CNRS 75013 Paris France
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Zhang L, Tong Y, Kelai M, Bellec A, Lagoute J, Chacon C, Girard Y, Rousset S, Boillot M, Rivière E, Mallah T, Otero E, Arrio M, Sainctavit P, Repain V. Anomalous Light‐Induced Spin‐State Switching for Iron(II) Spin‐Crossover Molecules in Direct Contact with Metal Surfaces. Angew Chem Int Ed Engl 2020; 59:13341-13346. [DOI: 10.1002/anie.202003896] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2020] [Revised: 04/22/2020] [Indexed: 01/11/2023]
Affiliation(s)
- Luqiong Zhang
- Institut de Minéralogie, de Physique des Matériaux et, de Cosmochimie, CNRS UMR7590 Sorbonne Université, MNHN 75252 Paris Cedex 5 France
| | - Yongfeng Tong
- Université de Paris Laboratoire Matériaux et Phénomènes Quantiques, CNRS 75013 Paris France
| | - Massine Kelai
- Université de Paris Laboratoire Matériaux et Phénomènes Quantiques, CNRS 75013 Paris France
| | - Amandine Bellec
- Université de Paris Laboratoire Matériaux et Phénomènes Quantiques, CNRS 75013 Paris France
| | - Jérôme Lagoute
- Université de Paris Laboratoire Matériaux et Phénomènes Quantiques, CNRS 75013 Paris France
| | - Cyril Chacon
- Université de Paris Laboratoire Matériaux et Phénomènes Quantiques, CNRS 75013 Paris France
| | - Yann Girard
- Université de Paris Laboratoire Matériaux et Phénomènes Quantiques, CNRS 75013 Paris France
| | - Sylvie Rousset
- Université de Paris Laboratoire Matériaux et Phénomènes Quantiques, CNRS 75013 Paris France
| | - Marie‐Laure Boillot
- Institut de Chimie Moléculaire et des Matériaux d'Orsay Univ Paris Sud Université Paris-Saclay CNRS, UMR 8182 91405 Orsay Cedex France
| | - Eric Rivière
- Institut de Chimie Moléculaire et des Matériaux d'Orsay Univ Paris Sud Université Paris-Saclay CNRS, UMR 8182 91405 Orsay Cedex France
| | - Talal Mallah
- Institut de Chimie Moléculaire et des Matériaux d'Orsay Univ Paris Sud Université Paris-Saclay CNRS, UMR 8182 91405 Orsay Cedex France
| | - Edwige Otero
- Synchrotron SOLEIL L'Orme des Merisiers Saint-Aubin 91192 Gif sur Yvette France
| | - Marie‐Anne Arrio
- Institut de Minéralogie, de Physique des Matériaux et, de Cosmochimie, CNRS UMR7590 Sorbonne Université, MNHN 75252 Paris Cedex 5 France
| | - Philippe Sainctavit
- Institut de Minéralogie, de Physique des Matériaux et, de Cosmochimie, CNRS UMR7590 Sorbonne Université, MNHN 75252 Paris Cedex 5 France
- Synchrotron SOLEIL L'Orme des Merisiers Saint-Aubin 91192 Gif sur Yvette France
| | - Vincent Repain
- Université de Paris Laboratoire Matériaux et Phénomènes Quantiques, CNRS 75013 Paris France
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Ossinger S, Kipgen L, Naggert H, Bernien M, Britton AJ, Nickel F, Arruda LM, Kumberg I, Engesser TA, Golias E, Näther C, Tuczek F, Kuch W. Effect of ligand methylation on the spin-switching properties of surface-supported spin-crossover molecules. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2020; 32:114003. [PMID: 31778990 DOI: 10.1088/1361-648x/ab5c92] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
X-ray absorption spectroscopy investigations of the spin-state switching of spin-crossover (SCO) complexes adsorbed on a highly-oriented pyrolytic graphite (HOPG) surface have shown so far that HOPG is a promising candidate to realize applications such as spintronic devices because of the stability of SCO complexes on HOPG and the possibility of highly efficient thermal and light-induced spin-state switching. Herein, we present the spin switching of several Fe(II) SCO complexes adsorbed on an HOPG surface with particular emphasis on the thermally induced spin transition behaviour with respect to different structural modifications. The complexes of the type [Fe(bpz)2(L)] (bpz = dihydrobis(pyrazolyl)borate, L = 1,10-phenanthroline, 2,2'-bipyridine) and their methylated derivatives exhibit SCO in the solid state with some differences regarding cooperative effects. However, in the vacuum-deposited thick films on quartz, complete and more gradual spin transition behavior is observable via UV/vis spectroscopy. In contrast to that, all complexes show large differences upon direct contact with HOPG. Whereas the unmodified complexes show thermal and light-induced SCO, the addition of e.g. two or four methyl groups leads to a partial or a complete loss of the SCO on the surface. The angle-dependent measurement of the N K-edge compared to calculations indicates that the complete SCO and HS-locked molecules on the surface exhibit a similar preferential orientation, whereas complexes undergoing an incomplete SCO exhibit a random orientation on the surface. These results are discussed in the light of molecule-substrate interactions.
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Affiliation(s)
- Sascha Ossinger
- Institut für Anorganische Chemie, Christian-Albrechts-Universität zu Kiel, Max-Eyth-Straße 2, 24118 Kiel, Germany
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