1
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Van Stappen C, Van Kuiken BE, Mörtel M, Ruotsalainen KO, Maganas D, Khusniyarov MM, DeBeer S. Correlating Valence and 2p3d RIXS Spectroscopies: A Ligand-Field Study of Spin-Crossover Iron(II). Inorg Chem 2024; 63:7386-7400. [PMID: 38587408 DOI: 10.1021/acs.inorgchem.4c00435] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/09/2024]
Abstract
The molecular spin-crossover phenomenon between high-spin (HS) and low-spin (LS) states is a promising route to next-generation information storage, sensing applications, and molecular spintronics. Spin-crossover complexes also provide a unique opportunity to study the ligand field (LF) properties of a system in both HS and LS states while maintaining the same ligand environment. Presently, we employ complementing valence and core-level spectroscopic methods to probe the electronic excited-state manifolds of the spin-crossover complex [FeII(H2B(pz)2)2phen]0. Light-induced excited spin-state trapping (LIESST) at liquid He temperatures is exploited to characterize magnetic and spectroscopic properties of the photoinduced HS state using SQUID magnetometry and magnetic circular dichroism spectroscopy. In parallel, Fe 2p3d RIXS spectroscopy is employed to examine the ΔS = 0, 1 excited LF states. These experimental studies are combined with state-of-the-art CASSCF/NEVPT2 and CASCI/NEVPT2 calculations characterizing the ground and LF excited states. Analysis of the acquired LF information further supports the notion that the spin-crossover of [FeII(H2B(pz)2)2phen]0 is asymmetric, evidenced by a decrease in eπ in the LS state. The results demonstrate the power of cross-correlating spectroscopic techniques with high and low LF information content to make accurate excited-state assignments, as well as the current capabilities of ab initio theory in interpreting these electronic properties.
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Affiliation(s)
- Casey Van Stappen
- Max Planck Institute for Chemical Energy Conversion, Stiftstrasse 34-36, 45470 Mülheim an der Ruhr, Germany
| | - Benjamin E Van Kuiken
- Max Planck Institute for Chemical Energy Conversion, Stiftstrasse 34-36, 45470 Mülheim an der Ruhr, Germany
- European XFEL, Holzkoppel 4, 22869 Schenefeld, Germany
| | - Max Mörtel
- Department of Chemistry and Pharmacy, Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), Egerlandstrasse 1, 91058 Erlangen, Germany
| | - Kari O Ruotsalainen
- Synchrotron SOLEIL, L'Orme des Merisiers, Départementale 128, 91190 Saint-Aubin, France
| | - Dimitrios Maganas
- Max-Planck-Institut für Kohlenforschung, Kaiser-Wilhelm-Platz 1, 45470 Mülheim an der Ruhr, Germany
| | - Marat M Khusniyarov
- Department of Chemistry and Pharmacy, Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), Egerlandstrasse 1, 91058 Erlangen, Germany
| | - Serena DeBeer
- Max Planck Institute for Chemical Energy Conversion, Stiftstrasse 34-36, 45470 Mülheim an der Ruhr, Germany
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2
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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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3
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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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4
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Magnetic molecules on surfaces: SMMs and beyond. Coord Chem Rev 2023. [DOI: 10.1016/j.ccr.2022.214858] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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5
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Gavara-Edo M, Córdoba R, Valverde-Muñoz FJ, Herrero-Martín J, Real JA, Coronado E. Electrical Sensing of the Thermal and Light-Induced Spin Transition in Robust Contactless Spin-Crossover/Graphene Hybrid Devices. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2022; 34:e2202551. [PMID: 35766419 DOI: 10.1002/adma.202202551] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/19/2022] [Revised: 05/26/2022] [Indexed: 06/15/2023]
Abstract
Hybrid devices based on spin-crossover (SCO)/2D heterostructures grant a highly sensitive platform to detect the spin transition in the molecular SCO component and tune the properties of the 2D material. However, the fragility of the SCO materials upon thermal treatment, light irradiation, or contact with surfaces and the methodologies used for their processing have limited their applicability. Here, an easily processable and robust SCO/2D hybrid device with outstanding performance based on the sublimable SCO [Fe(Pyrz)2 ] molecule deposited over chemical vapor deposition (CVD) graphene is reported, which is fully compatible with electronics industry protocols. Thus, a novel methodology based on growing an elusive polymorph of [Fe(Pyrz)2 ] (tetragonal phase) over graphene is developed that allows a fast and effective light-induced spin transition in the devices (≈50% yield in 5 min) to be detected electrically. Such performance can be enhanced even more when a flexible polymeric layer of poly(methyl methacrylate) is inserted in between the two active components in a contactless configuration, reaching a ≈100% yield in 5 min.
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Affiliation(s)
- Miguel Gavara-Edo
- Institute of Molecular Science, University of Valencia, Catedrático José Beltrán 2, Paterna, 46980, Spain
| | - Rosa Córdoba
- Institute of Molecular Science, University of Valencia, Catedrático José Beltrán 2, Paterna, 46980, Spain
| | | | | | - José Antonio Real
- Institute of Molecular Science, University of Valencia, Catedrático José Beltrán 2, Paterna, 46980, Spain
| | - Eugenio Coronado
- Institute of Molecular Science, University of Valencia, Catedrático José Beltrán 2, Paterna, 46980, Spain
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6
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Gamage EH, Kamali S, Clark JK, Lee Y, Yox P, Shafer P, Yaroslavtsev AA, Ke L, Shatruk M, Kovnir K. As-Se Pentagonal Linkers to Induce Chirality and Polarity in Mixed-Valent Fe-Se Tetrahedral Chains Resulting in Hidden Magnetic Ordering. J Am Chem Soc 2022; 144:11283-11295. [PMID: 35700396 DOI: 10.1021/jacs.2c02936] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
A novel mixed-valent hybrid chiral and polar compound, Fe7As3Se12(en)6(H2O), has been synthesized by a single-step solvothermal method. The crystal structure consists of 1D [Fe5Se9] chains connected via [As3Se2]-Se pentagonal linkers and charge-balancing interstitial [Fe(en)3]2+ complexes (en = ethylenediamine). Neutron powder diffraction verified that interstitial water molecules participate in the crystal packing. Magnetic polarizability of the produced compound was confirmed by X-ray magnetic circular dichroism (XMCD) spectroscopy. X-ray absorption spectroscopy (XAS) and 57Fe Mössbauer spectroscopy showed the presence of mixed-valent Fe2+/Fe3+ in the Fe-Se chains. Magnetic susceptibility measurements reveal strong antiferromagnetic nearest neighbor interactions within the chains with no apparent magnetic ordering down to 2 K. Hidden short-range magnetic ordering below 70 K was found by 57Fe Mössbauer spectroscopy, showing that a fraction of the Fe3+/Fe2+ in the chains are magnetically ordered. Nevertheless, complete magnetic ordering is not achieved even at 6 K. Analysis of XAS spectra demonstrates that the fraction of Fe3+ in the chain increases with decreasing temperature. Computational analysis points out several competing ferrimagnetic ordered models within a single chain. This competition, together with variation in the Fe oxidation state and additional weak intrachain interactions, is hypothesized to prevent long-range magnetic ordering.
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Affiliation(s)
- Eranga H Gamage
- Department of Chemistry, Iowa State University, Ames, Iowa 50011, United States.,Ames Laboratory, U.S. Department of Energy, Ames, Iowa 50011, United States
| | - Saeed Kamali
- Mechanical, Aerospace & Biomedical Engineering Department, University of Tennessee Space Institute, Tullahoma, Tennessee 37388, United States.,Department of Physics and Astronomy, Middle Tennessee State University, Murfreesboro, Tennessee 37132, United States
| | - Judith K Clark
- Department of Chemistry and Biochemistry, Florida State University, Tallahassee, Florida 32306, United States
| | - Yongbin Lee
- Ames Laboratory, U.S. Department of Energy, Ames, Iowa 50011, United States
| | - Philip Yox
- Department of Chemistry, Iowa State University, Ames, Iowa 50011, United States.,Ames Laboratory, U.S. Department of Energy, Ames, Iowa 50011, United States
| | - Padraic Shafer
- Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States
| | | | - Liqin Ke
- Ames Laboratory, U.S. Department of Energy, Ames, Iowa 50011, United States
| | - Michael Shatruk
- Department of Chemistry and Biochemistry, Florida State University, Tallahassee, Florida 32306, United States.,National High Magnetic Field Laboratory, 1800 E Paul Dirac Dr, Tallahassee, Florida 32310, United States
| | - Kirill Kovnir
- Department of Chemistry, Iowa State University, Ames, Iowa 50011, United States.,Ames Laboratory, U.S. Department of Energy, Ames, Iowa 50011, United States
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7
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Hao G, Dale AS, N'Diaye AT, Chopdekar RV, Koch RJ, Jiang X, Mellinger C, Zhang J, Cheng R, Xu X, Dowben PA. Intermolecular interaction and cooperativity in an Fe(II) spin crossover molecular thin film system. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2022; 34:295201. [PMID: 35508146 DOI: 10.1088/1361-648x/ac6cbc] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/22/2022] [Accepted: 05/04/2022] [Indexed: 06/14/2023]
Abstract
Compact domain features have been observed in spin crossover [Fe{H2B(pz)2}2(bipy)] molecular thin film systems via soft x-ray absorption spectroscopy and photoemission electron microscopy. The domains are in a mixed spin state that on average corresponds to roughly 2/3 the high spin occupation of the pure high spin state. Monte Carlo simulations support the presence of intermolecular interactions that can be described in terms of an Ising model in which interactions beyond nearest-neighbors cannot be neglected. This suggests the presence of short-range order to permit interactions between molecules beyond nearest neighbor that contribute to the formation of largely high spin state domains structure. The formation of a spin state domain structure appears to be the result of extensive cooperative effects.
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Affiliation(s)
- Guanhua Hao
- Department of Physics and Astronomy, Jorgensen Hall, University of Nebraska, Lincoln, NE 68588, United States of America
- Advanced Light Source, Lawrence Berkeley National Lab, One Cyclotron Rd, Berkeley, CA 94720, United States of America
| | - Ashley S Dale
- Department of Physics, Indiana University-Purdue University Indianapolis, Indianapolis, Indiana 46202, United States of America
| | - Alpha T N'Diaye
- Advanced Light Source, Lawrence Berkeley National Lab, One Cyclotron Rd, Berkeley, CA 94720, United States of America
| | - Rajesh V Chopdekar
- Advanced Light Source, Lawrence Berkeley National Lab, One Cyclotron Rd, Berkeley, CA 94720, United States of America
| | - Roland J Koch
- Advanced Light Source, Lawrence Berkeley National Lab, One Cyclotron Rd, Berkeley, CA 94720, United States of America
| | - Xuanyuan Jiang
- Department of Physics and Astronomy, Jorgensen Hall, University of Nebraska, Lincoln, NE 68588, United States of America
| | - Corbyn Mellinger
- Department of Physics and Astronomy, Jorgensen Hall, University of Nebraska, Lincoln, NE 68588, United States of America
| | - Jian Zhang
- The Molecular Foundry, Lawrence Berkeley National Laboratory, One Cyclotron Road, Berkeley, CA 94720, United States of America
| | - Ruihua Cheng
- Department of Physics, Indiana University-Purdue University Indianapolis, Indianapolis, Indiana 46202, United States of America
| | - Xiaoshan Xu
- Department of Physics and Astronomy, Jorgensen Hall, University of Nebraska, Lincoln, NE 68588, United States of America
| | - Peter A Dowben
- Department of Physics and Astronomy, Jorgensen Hall, University of Nebraska, Lincoln, NE 68588, United States of America
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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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Magnetic Field Perturbations to a Soft X-ray-Activated Fe (II) Molecular Spin State Transition. MAGNETOCHEMISTRY 2021. [DOI: 10.3390/magnetochemistry7100135] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
The X-ray-induced spin crossover transition of an Fe (II) molecular thin film in the presence and absence of a magnetic field has been investigated. The thermal activation energy barrier in the soft X-ray activation of the spin crossover transition for [Fe{H2B(pz)2}2(bipy)] molecular thin films is reduced in the presence of an applied magnetic field, as measured through X-ray absorption spectroscopy at various temperatures. The influence of a 1.8 T magnetic field is sufficient to cause deviations from the expected exponential spin state transition behavior which is measured in the field free case. We find that orbital moment diminishes with increasing temperature, relative to the spin moment in the vicinity of room temperature.
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11
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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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12
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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: 32] [Impact Index Per Article: 10.7] [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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13
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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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14
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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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15
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Iglesias S, Gamonal A, Abudulimu A, Picón A, Carrasco E, Écija D, Liu C, Luer L, Zhang X, Costa JS, Moonshiram D. Tracking the Light-Induced Excited-State Dynamics and Structural Configurations of an Extraordinarily Long-Lived Metastable State at Room Temperature. Chemistry 2020; 26:10801-10810. [PMID: 32452581 DOI: 10.1002/chem.202001393] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2020] [Revised: 05/22/2020] [Indexed: 11/11/2022]
Abstract
Time-resolved X-ray (Tr-XAS) and optical transient absorption (OTA) spectroscopy on the pico-microsecond timescale coupled with density functional theory calculations are applied to study the light-induced spin crossover processes of a Fe-based macrocyclic complex in solution. Tr-XAS analysis after light illumination shows the formation of a seven-coordinated high-spin quintet metastable state, which relaxes to a six-coordinated high-spin configuration before decaying to the ground state. Kinetic analysis of the macrocyclic complex reveals an unprecedented long-lived decay lifetime of approximately 42.6 μs. Comparative studies with a non-macrocyclic counterpart illustrate a significantly shortened approximately 568-fold decay lifetime of about 75 ns, and highlight the importance of the ligand arrangement in stabilizing the reactivity of the excited state. Lastly, OTA analysis shows the seven-coordinated high-spin state to be formed within approximately 6.2 ps. These findings provide a complete understanding of the spin crossover reaction and relaxation pathways of the macrocyclic complex, and reveal the importance of a flexible coordination environment for their rational design.
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Affiliation(s)
- Sirma Iglesias
- Instituto Madrileño de Estudios Avanzados en, Nanociencia (IMDEA Nanociencia), Calle Faraday 9, 28049, Madrid, Spain
| | - Arturo Gamonal
- Instituto Madrileño de Estudios Avanzados en, Nanociencia (IMDEA Nanociencia), Calle Faraday 9, 28049, Madrid, Spain
| | - Abasi Abudulimu
- Instituto Madrileño de Estudios Avanzados en, Nanociencia (IMDEA Nanociencia), Calle Faraday 9, 28049, Madrid, Spain
| | - Antonio Picón
- Departamento de Química, Universidad Autónoma de Madrid, 28049, Madrid, Spain
| | - Esther Carrasco
- Instituto Madrileño de Estudios Avanzados en, Nanociencia (IMDEA Nanociencia), Calle Faraday 9, 28049, Madrid, Spain
| | - David Écija
- Instituto Madrileño de Estudios Avanzados en, Nanociencia (IMDEA Nanociencia), Calle Faraday 9, 28049, Madrid, Spain
| | - Cunming Liu
- X-ray Science Division, Argonne National Laboratory, 9700 S. Cass Avenue, Lemont, IL, 60439, USA
| | - Larry Luer
- Instituto Madrileño de Estudios Avanzados en, Nanociencia (IMDEA Nanociencia), Calle Faraday 9, 28049, Madrid, Spain.,Institute of Materials for Electronics and Energy Technology (i-MEET), Friedrich-Alexander University Erlangen-Nürnberg, Martensstraße 7, 91058, Erlangen, Germany
| | - Xiaoyi Zhang
- X-ray Science Division, Argonne National Laboratory, 9700 S. Cass Avenue, Lemont, IL, 60439, USA
| | - José Sánchez Costa
- Instituto Madrileño de Estudios Avanzados en, Nanociencia (IMDEA Nanociencia), Calle Faraday 9, 28049, Madrid, Spain
| | - Dooshaye Moonshiram
- Instituto Madrileño de Estudios Avanzados en, Nanociencia (IMDEA Nanociencia), Calle Faraday 9, 28049, Madrid, Spain
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16
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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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17
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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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18
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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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19
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Ossinger S, Näther C, Buchholz A, Schmidtmann M, Mangelsen S, Beckhaus R, Plass W, Tuczek F. Spin Transition of an Iron(II) Organoborate Complex in Different Polymorphs and in Vacuum-Deposited Thin Films: Influence of Cooperativity. Inorg Chem 2020; 59:7966-7979. [PMID: 32036663 DOI: 10.1021/acs.inorgchem.9b03354] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
Two polymorphic modifications (1-I and 1-II) of the new spin crossover (SCO) complex [Fe{H2B(pz)(pypz)}2] (pz = pyrazole, pypz = pyridylpyrazole; 1) were prepared and investigated by differential scanning calorimetry (DSC), magnetic measurements, Mößbauer, vibrational, and absorption spectroscopy as well as single-crystal and X-ray powder diffraction. DSC measurements reveal that upon heating the thermodynamically metastable form 1-II to ∼178 °C it transforms into 1-I in an exothermic reaction, which proves that these modifications are related by monotropism. Both forms show thermal SCO with T1/2 values of 390 K (1-II) and 270 K (1-I). An analysis of the crystal structures of 1-II and the corresponding Zn(II) (2) and Co(II) (3) complexes that are isotypic with 1-I reveals that form II consists of dimers coupled by strong intramolecular π···π interactions, which is not the case for 1-I. In agreement with these findings, investigations of thin films of 1, where significant π···π interactions should be absent, reveal SCO behavior similar to that of 1-I. These results underscore the importance of cooperativity for the spin-transition behavior of this class of complexes.
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Affiliation(s)
- Sascha Ossinger
- Institute of Inorganic Chemistry, Christian-Albrechts-University Kiel, Max-Eyth-Str.2, 24118 Kiel, Germany
| | - Christian Näther
- Institute of Inorganic Chemistry, Christian-Albrechts-University Kiel, Max-Eyth-Str.2, 24118 Kiel, Germany
| | - Axel Buchholz
- Institute of Inorganic and Analytical Chemistry, Friedrich-Schiller-University, 07743 Jena, Germany
| | - Marc Schmidtmann
- Institute for Chemistry, Carl von Ossietzky University Oldenburg, 26111 Oldenburg, Germany
| | - Sebastian Mangelsen
- Institute of Inorganic Chemistry, Christian-Albrechts-University Kiel, Max-Eyth-Str.2, 24118 Kiel, Germany
| | - Rüdiger Beckhaus
- Institute for Chemistry, Carl von Ossietzky University Oldenburg, 26111 Oldenburg, Germany
| | - Winfried Plass
- Institute of Inorganic and Analytical Chemistry, Friedrich-Schiller-University, 07743 Jena, Germany
| | - Felix Tuczek
- Institute of Inorganic Chemistry, Christian-Albrechts-University Kiel, Max-Eyth-Str.2, 24118 Kiel, Germany
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20
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Ossinger S, Naggert H, Bill E, Näther C, Tuczek F. Electronic Structure, Vibrational Spectra, and Spin-Crossover Properties of Vacuum-Evaporable Iron(II) Bis(dihydrobis(pyrazolyl)borate) Complexes with Diimine Coligands. Origin of Giant Raman Features. Inorg Chem 2019; 58:12873-12887. [DOI: 10.1021/acs.inorgchem.9b01813] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Sascha Ossinger
- Institute of Inorganic Chemistry, Christian-Albrechts-University Kiel, Max-Eyth-Strasse 2, 24118 Kiel, Germany
| | - Holger Naggert
- Institute of Inorganic Chemistry, Christian-Albrechts-University Kiel, Max-Eyth-Strasse 2, 24118 Kiel, Germany
| | - Eckhard Bill
- Max Planck Institute for Chemical Energy Conversion, Stiftstrasse 34-36, 45470 Mülheim an der Ruhr, Germany
| | - Christian Näther
- Institute of Inorganic Chemistry, Christian-Albrechts-University Kiel, Max-Eyth-Strasse 2, 24118 Kiel, Germany
| | - Felix Tuczek
- Institute of Inorganic Chemistry, Christian-Albrechts-University Kiel, Max-Eyth-Strasse 2, 24118 Kiel, Germany
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21
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Kipgen L, Bernien M, Ossinger S, Nickel F, Britton AJ, Arruda LM, Naggert H, Luo C, Lotze C, Ryll H, Radu F, Schierle E, Weschke E, Tuczek F, Kuch W. Evolution of cooperativity in the spin transition of an iron(II) complex on a graphite surface. Nat Commun 2018; 9:2984. [PMID: 30061654 PMCID: PMC6065309 DOI: 10.1038/s41467-018-05399-8] [Citation(s) in RCA: 52] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2018] [Accepted: 07/05/2018] [Indexed: 11/09/2022] Open
Abstract
Cooperative effects determine the spin-state bistability of spin-crossover molecules (SCMs). Herein, the ultimate scale limit at which cooperative spin switching becomes effective is investigated in a complex [Fe(H2B(pz)2)2(bipy)] deposited on a highly oriented pyrolytic graphite surface, using x-ray absorption spectroscopy. This system exhibits a complete thermal- and light-induced spin transition at thicknesses ranging from submonolayers to multilayers. On increasing the coverage from 0.35(4) to 10(1) monolayers, the width of the temperature-induced spin transition curve narrows significantly, evidencing the buildup of cooperative effects. While the molecules at the submonolayers exhibit an apparent anticooperative behavior, the multilayers starting from a double-layer exhibit a distinctly cooperative spin switching, with a free-molecule-like behavior indicated at around a monolayer. These observations will serve as useful guidelines in designing SCM-based devices.
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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
| | - Sascha Ossinger
- Institut für Anorganische Chemie, Christian-Albrechts-Universität zu Kiel, Max-Eyth-Straße 2, 24118, Kiel, Germany
| | - Fabian Nickel
- Institut für Experimentalphysik, Freie Universität Berlin, Arnimallee 14, 14195, Berlin, Germany
| | - Andrew J Britton
- Institut für Experimentalphysik, Freie Universität Berlin, Arnimallee 14, 14195, Berlin, Germany
| | - Lucas M Arruda
- Institut für Experimentalphysik, Freie Universität Berlin, Arnimallee 14, 14195, Berlin, Germany
| | - Holger Naggert
- Institut für Anorganische Chemie, Christian-Albrechts-Universität zu Kiel, Max-Eyth-Straße 2, 24118, Kiel, Germany
| | - Chen Luo
- Institut für Experimentelle and Angewandte Physik, Universität Regensburg, Universitätsstrasse 31, 93053, Regensburg, Germany
| | - Christian Lotze
- Institut für Experimentalphysik, Freie Universität Berlin, Arnimallee 14, 14195, Berlin, Germany
| | - Hanjo Ryll
- Helmholtz-Zentrum Berlin für Materialien und Energie, Albert-Einstein-Straße 15, 12489, Berlin, Germany
| | - Florin Radu
- Helmholtz-Zentrum Berlin für Materialien und Energie, Albert-Einstein-Straße 15, 12489, Berlin, Germany
| | - Enrico Schierle
- Helmholtz-Zentrum Berlin für Materialien und Energie, Albert-Einstein-Straße 15, 12489, Berlin, Germany
| | - Eugen Weschke
- Helmholtz-Zentrum Berlin für Materialien und Energie, Albert-Einstein-Straße 15, 12489, 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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Rohlf S, Gruber M, Flöser BM, Grunwald J, Jarausch S, Diekmann F, Kalläne M, Jasper-Toennies T, Buchholz A, Plass W, Berndt R, Tuczek F, Rossnagel K. Light-Induced Spin Crossover in an Fe(II) Low-Spin Complex Enabled by Surface Adsorption. J Phys Chem Lett 2018; 9:1491-1496. [PMID: 29510617 DOI: 10.1021/acs.jpclett.8b00338] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
Understanding and controlling the spin-crossover properties of molecular complexes can be of particular interest for potential applications in molecular spintronics. Using near-edge X-ray absorption fine structure spectroscopy, we investigated these properties for a new vacuum-evaporable Fe(II) complex, namely [Fe(pypyr(CF3)2)2(phen)] (pypyr = 2-(2'-pyridyl)pyrrolide, phen = 1,10-phenanthroline). We find that the spin-transition temperature, well above room temperature for the bulk compound, is drastically lowered for molecules arranged in thin films. Furthermore, while within the experimentally accessible temperature range (2 K < T < 410 K) the bulk material shows indication of neither light-induced excited spin-state trapping nor soft X-ray-induced excited spin-state trapping, these effects are observed for molecules within thin films up to temperatures around 100 K. Thus, by arranging the molecules into thin films, a nominal low-spin complex is effectively transformed into a spin-crossover complex.
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Affiliation(s)
- Sebastian Rohlf
- Institut für Experimentelle und Angewandte Physik , Christian-Albrechts-Universität zu Kiel , 24098 Kiel , Germany
| | - Manuel Gruber
- Institut für Experimentelle und Angewandte Physik , Christian-Albrechts-Universität zu Kiel , 24098 Kiel , Germany
| | - Benedikt M Flöser
- Institut für Anorganische Chemie , Christian-Albrechts-Universität zu Kiel , 24098 Kiel , Germany
| | - Jan Grunwald
- Institut für Anorganische Chemie , Christian-Albrechts-Universität zu Kiel , 24098 Kiel , Germany
| | - Simon Jarausch
- Institut für Experimentelle und Angewandte Physik , Christian-Albrechts-Universität zu Kiel , 24098 Kiel , Germany
| | - Florian Diekmann
- Institut für Experimentelle und Angewandte Physik , Christian-Albrechts-Universität zu Kiel , 24098 Kiel , Germany
| | - Matthias Kalläne
- Institut für Experimentelle und Angewandte Physik , Christian-Albrechts-Universität zu Kiel , 24098 Kiel , Germany
- Ruprecht-Haensel-Labor , Christian-Albrechts-Universität zu Kiel und Deutsches Elektronen-Synchrotron DESY , 24098 Kiel und 22607 Hamburg , Germany
| | - Torben Jasper-Toennies
- Institut für Experimentelle und Angewandte Physik , Christian-Albrechts-Universität zu Kiel , 24098 Kiel , Germany
| | - Axel Buchholz
- Institut für Anorganische und Analytische Chemie, Friedrich-Schiller-Universität , 07743 Jena , Germany
| | - Winfried Plass
- Institut für Anorganische und Analytische Chemie, Friedrich-Schiller-Universität , 07743 Jena , Germany
| | - Richard Berndt
- Institut für Experimentelle und Angewandte Physik , Christian-Albrechts-Universität zu Kiel , 24098 Kiel , Germany
| | - Felix Tuczek
- Institut für Anorganische Chemie , Christian-Albrechts-Universität zu Kiel , 24098 Kiel , Germany
| | - Kai Rossnagel
- Institut für Experimentelle und Angewandte Physik , Christian-Albrechts-Universität zu Kiel , 24098 Kiel , Germany
- Ruprecht-Haensel-Labor , Christian-Albrechts-Universität zu Kiel und Deutsches Elektronen-Synchrotron DESY , 24098 Kiel und 22607 Hamburg , Germany
- Deutsches Elektronen-Synchrotron DESY , 22607 Hamburg , Germany
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23
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Kumar KS, Studniarek M, Heinrich B, Arabski J, Schmerber G, Bowen M, Boukari S, Beaurepaire E, Dreiser J, Ruben M. Engineering On-Surface Spin Crossover: Spin-State Switching in a Self-Assembled Film of Vacuum-Sublimable Functional Molecule. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2018; 30:1705416. [PMID: 29356142 DOI: 10.1002/adma.201705416] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/19/2017] [Revised: 11/12/2017] [Indexed: 06/07/2023]
Abstract
The realization of spin-crossover (SCO)-based applications requires study of the spin-state switching characteristics of SCO complex molecules within nanostructured environments, especially on surfaces. Except for a very few cases, the SCO of a surface-bound thin molecular film is either quenched or heavily altered due to: (i) molecule-surface interactions and (ii) differing intermolecular interactions in films relative to the bulk. By fabricating SCO complexes on a weakly interacting surface, the interfacial quenching problem is tackled. However, engineering intermolecular interactions in thin SCO active films is rather difficult. Here, a molecular self-assembly strategy is proposed to fabricate thin spin-switchable surface-bound films with programmable intermolecular interactions. Molecular engineering of the parent complex system [Fe(H2 B(pz)2 )2 (bpy)] (pz = pyrazole, bpy = 2,2'-bipyridine) with a dodecyl (C12 ) alkyl chain yields a classical amphiphile-like functional and vacuum-sublimable charge-neutral FeII complex, [Fe(H2 B(pz)2 )2 (C12 -bpy)] (C12 -bpy = dodecyl[2,2'-bipyridine]-5-carboxylate). Both the bulk powder and 10 nm thin films sublimed onto either quartz glass or SiOx surfaces of the complex show comparable spin-state switching characteristics mediated by similar lamellar bilayer like self-assembly/molecular interactions. This unprecedented observation augurs well for the development of SCO-based applications, especially in molecular spintronics.
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Affiliation(s)
- Kuppusamy Senthil Kumar
- Institut de Physique et Chimie des Matériaux (IPCMS), Université de Strasbourg, F-67034, Strasbourg, France
| | - Michał Studniarek
- Institut de Physique et Chimie des Matériaux (IPCMS), Université de Strasbourg, F-67034, Strasbourg, France
- Swiss Light Source, Paul Scherrer Institut (PSI), CH-5232, Villigen, Switzerland
| | - Benoît Heinrich
- Institut de Physique et Chimie des Matériaux (IPCMS), Université de Strasbourg, F-67034, Strasbourg, France
| | - Jacek Arabski
- Institut de Physique et Chimie des Matériaux (IPCMS), Université de Strasbourg, F-67034, Strasbourg, France
| | - Guy Schmerber
- Institut de Physique et Chimie des Matériaux (IPCMS), Université de Strasbourg, F-67034, Strasbourg, France
| | - Martin Bowen
- Institut de Physique et Chimie des Matériaux (IPCMS), Université de Strasbourg, F-67034, Strasbourg, France
| | - Samy Boukari
- Institut de Physique et Chimie des Matériaux (IPCMS), Université de Strasbourg, F-67034, Strasbourg, France
| | - Eric Beaurepaire
- Institut de Physique et Chimie des Matériaux (IPCMS), Université de Strasbourg, F-67034, Strasbourg, France
| | - Jan Dreiser
- Swiss Light Source, Paul Scherrer Institut (PSI), CH-5232, Villigen, Switzerland
| | - Mario Ruben
- Institut de Physique et Chimie des Matériaux (IPCMS), Université de Strasbourg, F-67034, Strasbourg, France
- Institute of Nanotechnology (INT), Karlsruhe Institute of Technology (KIT), Hermann-von-Helmholtz-Platz 1, D-76344, Eggenstein-Leopoldshafen, Germany
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