1
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Gómez-Coca S, Ruiz E. Benchmarking Periodic Density Functional Theory Calculations for Spin-State Energies in Spin-Crossover Systems. Inorg Chem 2024; 63:13338-13345. [PMID: 38976861 PMCID: PMC11270997 DOI: 10.1021/acs.inorgchem.4c01094] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2024] [Revised: 06/14/2024] [Accepted: 06/17/2024] [Indexed: 07/10/2024]
Abstract
Spin energetics is one of the biggest challenges associated with energy calculations for electronic structure methods. The energy differences of the spin states in spin-crossover compounds are very small, making them one of the most difficult systems to calculate. Few methods provide accurate results for calculating these energy differences. In addition, studies have usually focused on calculating energetics of single molecules, while spin-crossover properties are usually experimentally studied in the solid phase. In this paper, we have used periodic boundary conditions employing methods based on density functional theory to calculate the high- and low-spin energy differences for a test case of 20 extended systems. Compounds with different metals and ligands have been selected, and the results indicate that a semiquantitative description of the energy differences can be obtained with the combination of geometry optimization using the PBE functional including many-body dispersion approach and the use of meta-GGA functionals, such as r2SCAN but especially KTBM24, for the energy calculation. Other hybrid functionals, such as TPSSh, give generally good results, but the calculation of the exact exchange with periodic boundary conditions involves a huge increase in computer time and computational resources. It makes the proposed nonhybrid functional approach (KTBM24//PBE+MB) a great advantage for the study of periodic systems.
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Affiliation(s)
- Silvia Gómez-Coca
- Departament de Química
Inorgànica i Orgànica and Institut de Recerca de Química
Teòrica i Computacional, Universitat
de Barcelona, Barcelona 08028, Spain
| | - Eliseo Ruiz
- Departament de Química
Inorgànica i Orgànica and Institut de Recerca de Química
Teòrica i Computacional, Universitat
de Barcelona, Barcelona 08028, Spain
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2
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Jin H, Merz KM. Modeling Fe(II) Complexes Using Neural Networks. J Chem Theory Comput 2024; 20:2551-2558. [PMID: 38439716 PMCID: PMC10976644 DOI: 10.1021/acs.jctc.4c00063] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2024] [Revised: 02/18/2024] [Accepted: 02/22/2024] [Indexed: 03/06/2024]
Abstract
We report a Fe(II) data set of more than 23000 conformers in both low-spin (LS) and high-spin (HS) states. This data set was generated to develop a neural network model that is capable of predicting the energy and the energy splitting as a function of the conformation of a Fe(II) organometallic complex. In order to achieve this, we propose a type of scaled electronic embedding to cover the long-range interactions implicitly in our neural network describing the Fe(II) organometallic complexes. For the total energy prediction, the lowest MAE is 0.037 eV, while the lowest MAE of the splitting energy is 0.030 eV. Compared to baseline models, which only incorporate short-range interactions, our scaled electronic embeddings improve the accuracy by over 70% for the prediction of the total energy and the splitting energy. With regard to semiempirical methods, our proposed models reduce the MAE, with respect to these methods, by 2 orders of magnitude.
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Affiliation(s)
- Hongni Jin
- Department
of Chemistry, Michigan State University, East Lansing, Michigan 48824, United States
| | - Kenneth M. Merz
- Department
of Chemistry, Michigan State University, East Lansing, Michigan 48824, United States
- Department
of Biochemistry and Molecular Biology, Michigan
State University, East Lansing, Michigan 48824, United States
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3
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Rabelo R, Toma L, Julve M, Lloret F, Pasán J, Cangussu D, Ruiz-García R, Cano J. How the spin state tunes the slow magnetic relaxation field dependence in spin crossover cobalt(II) complexes. Dalton Trans 2024; 53:5507-5520. [PMID: 38416047 DOI: 10.1039/d4dt00059e] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/29/2024]
Abstract
A novel family of cobalt(II) compounds with tridentate pyridine-2,6-diiminephenyl type ligands featuring electron-withdrawing substituents of general formula [Co(n-XPhPDI)2](ClO4)2·S [n-XPhPDI = 2,6-bis(N-n-halophenylformimidoyl)pyridine with n = 4 (1-3) and 3 (4); X = I (1), Br (2 and 4) and Cl (3); S = MeCN (1 and 2) and EtOAc (3)] has been synthesised and characterised by single-crystal X-ray diffraction, electron paramagnetic resonance, and static (dc) and dynamic (ac) magnetic measurements combined with theoretical calculations. The structures of 1-4 consist of mononuclear bis(chelating) cobalt(II) complex cations, [CoII(n-XPhPDI)2]2+, perchlorate anions, and acetonitrile (1 and 2) or ethyl acetate (3) molecules of crystallisation. This unique series of mononuclear six-coordinate octahedral cobalt(II) complexes displays both thermally-induced low-spin (LS)/high-spin (HS) transition and field-induced slow magnetic relaxation in both LS and HS states. A complete LS ↔ HS transition occurs for 1 and 2, while it is incomplete for 4, one-third of the complexes being HS at low temperatures. In contrast, 3 remains HS in all the temperature range. 1 and 2 show dual spin relaxation dynamics under the presence of an applied dc magnetic field (Hdc), with the occurrence of faster- (FR) and slower-relaxing (SR) processes at lower (Hdc = 1.0 kOe) and higher fields (Hdc = 2.5 kOe), respectively. On the contrary, 3 and 4 exhibit only SR and FR relaxations, regardless of Hdc. Overall, the distinct field-dependence of the single-molecule magnet (SMM) behaviour along with this family of spin-crossover (SCO) cobalt(II)-n-XPhPDI complexes is dominated by Raman mechanisms and, occasionally, with additional temperature-independent Intra-Kramer [LS or HS (D > 0)] or Quantum Tunneling of Magnetisation mechanisms [HS (D < 0)] also contributing.
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Affiliation(s)
- Renato Rabelo
- Instituto de Ciencia Molecular (ICMol), Universitat de València, 46980 Paterna, València, Spain.
- Instituto de Química, Universidade Federal de Goiás, Av. Esperança Campus Samambaia, Goiânia, GO, Brazil
| | - Luminita Toma
- Instituto de Ciencia Molecular (ICMol), Universitat de València, 46980 Paterna, València, Spain.
| | - Miguel Julve
- Instituto de Ciencia Molecular (ICMol), Universitat de València, 46980 Paterna, València, Spain.
| | - Francesc Lloret
- Instituto de Ciencia Molecular (ICMol), Universitat de València, 46980 Paterna, València, Spain.
| | - Jorge Pasán
- Laboratorio de Materiales para Análisis Químico (MAT4LL), Departamento de Química, Facultad de Ciencias, Universidad de La Laguna, 38200 Tenerife, Spain
| | - Danielle Cangussu
- Instituto de Química, Universidade Federal de Goiás, Av. Esperança Campus Samambaia, Goiânia, GO, Brazil
| | - Rafael Ruiz-García
- Instituto de Ciencia Molecular (ICMol), Universitat de València, 46980 Paterna, València, Spain.
| | - Joan Cano
- Instituto de Ciencia Molecular (ICMol), Universitat de València, 46980 Paterna, València, Spain.
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4
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Vennelakanti V, Kilic IB, Terrones GG, Duan C, Kulik HJ. Machine Learning Prediction of the Experimental Transition Temperature of Fe(II) Spin-Crossover Complexes. J Phys Chem A 2024; 128:204-216. [PMID: 38148525 DOI: 10.1021/acs.jpca.3c07104] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2023]
Abstract
Spin-crossover (SCO) complexes are materials that exhibit changes in the spin state in response to external stimuli, with potential applications in molecular electronics. It is challenging to know a priori how to design ligands to achieve the delicate balance of entropic and enthalpic contributions needed to tailor a transition temperature close to room temperature. We leverage the SCO complexes from the previously curated SCO-95 data set [Vennelakanti et al. J. Chem. Phys. 159, 024120 (2023)] to train three machine learning (ML) models for transition temperature (T1/2) prediction using graph-based revised autocorrelations as features. We perform feature selection using random forest-ranked recursive feature addition (RF-RFA) to identify the features essential to model transferability. Of the ML models considered, the full feature set RF and recursive feature addition RF models perform best, achieving moderate correlation to experimental T1/2 values. We then compare ML T1/2 predictions to those from three previously identified best-performing density functional approximations (DFAs) which accurately predict SCO behavior across SCO-95, finding that the ML models predict T1/2 more accurately than the best-performing DFAs. In addition, we study ML model predictions for a set of 18 SCO complexes for which only estimated T1/2 values are available. Upon excluding outliers from this set, the RF-RFA RF model shows a strong correlation to estimated T1/2 values with a Pearson's r of 0.82. In contrast, DFA-predicted T1/2 values have large errors and show no correlation to estimated T1/2 values over the same set of complexes. Overall, our study demonstrates slightly superior performance of ML models in comparison with some of the best-performing DFAs, and we expect ML models to improve further as larger data sets of SCO complexes are curated and become available for model training.
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Affiliation(s)
- Vyshnavi Vennelakanti
- Department of Chemical Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States
| | - Irem B Kilic
- Department of Chemical Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States
| | - Gianmarco G Terrones
- Department of Chemical Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States
| | - Chenru Duan
- Department of Chemical Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States
| | - Heather J Kulik
- Department of Chemical Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States
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5
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Amamizu N, Nishida M, Sasaki K, Kishi R, Kitagawa Y. Theoretical Study on the Open-Shell Electronic Structure and Electron Conductivity of [18]Annulene as a Molecular Parallel Circuit Model. NANOMATERIALS (BASEL, SWITZERLAND) 2023; 14:98. [PMID: 38202553 PMCID: PMC10781064 DOI: 10.3390/nano14010098] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/21/2023] [Revised: 12/19/2023] [Accepted: 12/21/2023] [Indexed: 01/12/2024]
Abstract
Herein, the electron conductivities of [18]annulene and its derivatives are theoretically examined as a molecular parallel circuit model consisting of two linear polyenes. Their electron conductivities are estimated by elastic scattering Green's function (ESGF) theory and density functional theory (DFT) methods. The calculated conductivity of the [18]annulene does not follow the classical conductivity, i.e., Ohm's law, suggesting the importance of a quantum interference effect in single molecules. By introducing electron-withdrawing groups into the annulene framework, on the other hand, a spin-polarized electronic structure appears, and the quantum interference effect is significantly suppressed. In addition, the total current is affected by the spin polarization because of the asymmetry in the coupling constant between the molecule and electrodes. From these results, it is suggested that the electron conductivity as well as the quantum interference effect of π-conjugated molecular systems can be designed using their open-shell nature, which is chemically controlled by the substituents.
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Affiliation(s)
- Naoka Amamizu
- Department of Materials Engineering Science, Graduate School of Engineering Science, Osaka University, Toyonaka, Osaka 560-8531, Japan; (M.N.); (K.S.); (R.K.)
| | - Mitsuhiro Nishida
- Department of Materials Engineering Science, Graduate School of Engineering Science, Osaka University, Toyonaka, Osaka 560-8531, Japan; (M.N.); (K.S.); (R.K.)
| | - Keisuke Sasaki
- Department of Materials Engineering Science, Graduate School of Engineering Science, Osaka University, Toyonaka, Osaka 560-8531, Japan; (M.N.); (K.S.); (R.K.)
| | - Ryohei Kishi
- Department of Materials Engineering Science, Graduate School of Engineering Science, Osaka University, Toyonaka, Osaka 560-8531, Japan; (M.N.); (K.S.); (R.K.)
- Center for Quantum Information and Quantum Biology (QIQB), International Advanced Research Institute (IARI), Osaka University, Toyonaka, Osaka 560-0043, Japan
- Research Center for Solar Energy Chemistry (RCSEC), Graduate School of Engineering Science, Osaka University, Toyonaka, Osaka 560-8531, Japan
- Innovative Catalysis Science Division, Institute for Open and Transdisciplinary Research Initiatives (ICS-OTRI), Osaka University, Suita, Osaka 565-0871, Japan
| | - Yasutaka Kitagawa
- Department of Materials Engineering Science, Graduate School of Engineering Science, Osaka University, Toyonaka, Osaka 560-8531, Japan; (M.N.); (K.S.); (R.K.)
- Center for Quantum Information and Quantum Biology (QIQB), International Advanced Research Institute (IARI), Osaka University, Toyonaka, Osaka 560-0043, Japan
- Research Center for Solar Energy Chemistry (RCSEC), Graduate School of Engineering Science, Osaka University, Toyonaka, Osaka 560-8531, Japan
- Innovative Catalysis Science Division, Institute for Open and Transdisciplinary Research Initiatives (ICS-OTRI), Osaka University, Suita, Osaka 565-0871, Japan
- Spintronics Research Network Division, Institute for Open and Transdisciplinary Research Initiatives (SRN-OTRI), Osaka University, Toyonaka, Osaka 560-8531, Japan
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6
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Albavera-Mata A, Hennig RG, Trickey SB. Transition Temperature for Spin-Crossover Materials with the Mean Value Ensemble Hubbard- U Correction. J Phys Chem A 2023; 127:7646-7654. [PMID: 37669434 DOI: 10.1021/acs.jpca.3c03520] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 09/07/2023]
Abstract
Calculation of transition temperatures T1/2 for thermally driven spin-crossover in condensed phases is challenging, even with sophisticated state-of-the-art density functional approximations. The first issue is the accuracy of the adiabatic crossover energy difference ΔEHL between the low- and high-spin states of the bistable metal-organic complexes. The other is the proper inclusion of entropic contributions to the Gibbs free energy from the electronic and vibrational degrees of freedom. We discuss the effects of treatments of both contributions upon the calculation of thermochemical properties for a set of 20 spin-crossover materials using a Hubbard-U correction obtained from a reference ensemble spin-state. The U values obtained from a simplest bimolecular representation may overcorrect, somewhat, the ΔEHL values, hence giving somewhat excessive reduction of the T1/2 results with respect to their U = 0 values in the crystalline phase. We discuss the origins of the discrepancies by analyzing different sources of uncertainties. By use of a first-coordination-sphere approximation and the assumption that vibrational contributions from the outermost atoms in a metal-organic complex are similar in both low- and high-spin states, we achieve T1/2 results with the low-cost, widely used PBE generalized gradient density functional approximation comparable to those from the more costly, more sophisticated r2SCAN meta-generalized gradient approximation. The procedure is promising for use in high-throughput materials screening, because it combines rather low computational effort requirements with freedom from user manipulation of parameters.
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Affiliation(s)
- Angel Albavera-Mata
- Center for Molecular Magnetic Quantum Materials, Quantum Theory Project, University of Florida, Gainesville, Florida 32611, United States
- Department of Materials Science and Engineering, University of Florida, 1885 Stadium Road, Gainesville, Florida 32611, United States
| | - Richard G Hennig
- Center for Molecular Magnetic Quantum Materials, Quantum Theory Project, University of Florida, Gainesville, Florida 32611, United States
- Department of Materials Science and Engineering, University of Florida, 1885 Stadium Road, Gainesville, Florida 32611, United States
| | - S B Trickey
- Center for Molecular Magnetic Quantum Materials, Quantum Theory Project, University of Florida, Gainesville, Florida 32611, United States
- Department of Physics and Department of Chemistry, University of Florida, P.O. Box 118435, Gainesville, Florida 32611, United States
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7
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Review of Fe-based spin crossover metal complexes in multiscale device architectures. Inorganica Chim Acta 2023. [DOI: 10.1016/j.ica.2022.121168] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
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8
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Dynamics of Spin Crossover Molecular Complexes. NANOMATERIALS 2022; 12:nano12101742. [PMID: 35630963 PMCID: PMC9144206 DOI: 10.3390/nano12101742] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/31/2022] [Revised: 05/09/2022] [Accepted: 05/16/2022] [Indexed: 02/04/2023]
Abstract
We review the current understanding of the time scale and mechanisms associated with the change in spin state in transition metal-based spin crossover (SCO) molecular complexes. Most time resolved experiments, performed by optical techniques, rely on the intrinsic light-induced switching properties of this class of materials. The optically driven spin state transition can be mediated by a rich interplay of complexities including intermediate states in the spin state transition process, as well as intermolecular interactions, temperature, and strain. We emphasize here that the size reduction down to the nanoscale is essential for designing SCO systems that switch quickly as well as possibly retaining the memory of the light-driven state. We argue that SCO nano-sized systems are the key to device applications where the “write” speed is an important criterion.
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9
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Nadeem M, Cruddas J, Ruzzi G, Powell BJ. Toward High-Temperature Light-Induced Spin-State Trapping in Spin-Crossover Materials: The Interplay of Collective and Molecular Effects. J Am Chem Soc 2022; 144:9138-9148. [PMID: 35546521 DOI: 10.1021/jacs.2c03202] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
Spin-crossover (SCO) materials display many fascinating behaviors including collective phase transitions and spin-state switching controlled by external stimuli, e.g., light and electrical currents. As single-molecule switches, they have been fêted for numerous practical applications, but these remain largely unrealized-partly because of the difficulty of switching these materials at high temperatures. We introduce a semiempirical microscopic model of SCO materials combining crystal field theory with elastic intermolecular interactions. For realistic parameters, this model reproduces the key experimental results including thermally induced phase transitions, light-induced spin-state trapping (LIESST), and reverse-LIESST. Notably, we reproduce and explain the experimentally observed relationship between the critical temperature of the thermal transition, T1/2, and the highest temperature for which the trapped state is stable, TLIESST, and explain why increasing the stiffness of the coordination sphere increases TLIESST. We propose strategies to design SCO materials with higher TLIESST: optimizing the spin-orbit coupling via heavier atoms (particularly in the inner coordination sphere) and minimizing the enthalpy difference between the high-spin (HS) and low-spin (LS) states. However, the most dramatic increases arise from increasing the cooperativity of the spin-state transition by increasing the rigidity of the crystal. Increased crystal rigidity can also stabilize the HS state to low temperatures on thermal cycling yet leave the LS state stable at high temperatures following, for example, reverse-LIESST. We show that such highly cooperative systems offer a realistic route to robust room-temperature switching, demonstrate this in silico, and discuss material design rationale to realize this.
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Affiliation(s)
- M Nadeem
- School of Mathematics and Physics, The University of Queensland, Brisbane, Queensland 4072, Australia
| | - Jace Cruddas
- School of Physical Sciences, The University of Adelaide, Adelaide, SA 5005, Australia
| | - Gian Ruzzi
- School of Mathematics and Physics, The University of Queensland, Brisbane, Queensland 4072, Australia
| | - Benjamin J Powell
- School of Mathematics and Physics, The University of Queensland, Brisbane, Queensland 4072, Australia
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10
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Kuppusamy SK, Mizuno A, García-Fuente A, van der Poel S, Heinrich B, Ferrer J, van der Zant HSJ, Ruben M. Spin-Crossover in Supramolecular Iron(II)-2,6-bis(1 H-Pyrazol-1-yl)pyridine Complexes: Toward Spin-State Switchable Single-Molecule Junctions. ACS OMEGA 2022; 7:13654-13666. [PMID: 35559184 PMCID: PMC9088905 DOI: 10.1021/acsomega.1c07217] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/22/2021] [Accepted: 03/21/2022] [Indexed: 05/27/2023]
Abstract
Spin-crossover (SCO) active iron(II) complexes are an integral class of switchable and bistable molecular materials. Spin-state switching properties of the SCO complexes have been studied in the bulk and single-molecule levels to progress toward fabricating molecule-based switching and memory elements. Supramolecular SCO complexes featuring anchoring groups for metallic electrodes, for example, gold (Au), are ideal candidates to study spin-state switching at the single-molecule level. In this study, we report on the spin-state switching characteristics of supramolecular iron(II) complexes 1 and 2 composed of functional 4-([2,2'-bithiophen]-5-ylethynyl)-2,6-di(1H-pyrazol-1-yl)pyridine (L1) and 4-(2-(5-(5-hexylthiophen-2-yl)thiophen-2-yl)ethynyl)-2,6-di(1H-pyrazol-1-yl)pyridine (L2) ligands, respectively. Density functional theory (DFT) studies revealed stretching-induced spin-state switching in a molecular junction composed of complex 1, taken as a representative example, and gold electrodes. Single-molecule conductance traces revealed the unfavorable orientation of the complexes in the junctions to demonstrate the spin-state dependence of the conductance.
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Affiliation(s)
- Senthil Kumar Kuppusamy
- Institute
for Quantum Materials and Technologies (IQMT), Karlsruhe Institute of Technology (KIT), Hermann-von-Helmholtz-Platz 1, 76344 Eggenstein-Leopoldshafen, Germany
| | - Asato Mizuno
- Institute
of Nanotechnology, Karlsruhe Institute of
Technology (KIT), Hermann-von-Helmholtz-Platz 1, 76344 Eggenstein-Leopoldshafen, Germany
| | - Amador García-Fuente
- Departamento
de Física, Universidad de Oviedo, ES-33007 Oviedo, Spain
- Centro
de Investigación en Nanotecnología y Nanomateriales
(CINN, CSIC), El Entrego ES-33940, Spain
| | - Sebastiaan van der Poel
- Kavli
Institute of Nanoscience, Delft University of Technology, PO Box 5046, 2600 GA Delft, The Netherlands
| | - Benoît Heinrich
- Institut
de Physique et Chimie des Matériaux de Strasbourg (IPCMS), CNRS-Université de Strasbourg,
23, rue du Loess, BP 43, 67034 cedex
2 Strasbourg, France
| | - Jaime Ferrer
- Departamento
de Física, Universidad de Oviedo, ES-33007 Oviedo, Spain
- Centro
de Investigación en Nanotecnología y Nanomateriales
(CINN, CSIC), El Entrego ES-33940, Spain
| | - Herre S. J. van der Zant
- Kavli
Institute of Nanoscience, Delft University of Technology, PO Box 5046, 2600 GA Delft, The Netherlands
| | - Mario Ruben
- Institute
for Quantum Materials and Technologies (IQMT), Karlsruhe Institute of Technology (KIT), Hermann-von-Helmholtz-Platz 1, 76344 Eggenstein-Leopoldshafen, Germany
- Institute
of Nanotechnology, Karlsruhe Institute of
Technology (KIT), Hermann-von-Helmholtz-Platz 1, 76344 Eggenstein-Leopoldshafen, Germany
- Université
de Strasbourg (Unistra), Institute de Science et d′Ingénierie
Supramoléculaire (ISIS), Centre Européen de Science
Quantique (CESQ), 8,
Allée Gaspard Monge, F-67000 Strasbourg, France
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11
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Bondì L, Garden AL, Totti F, Jerabek P, Brooker S. Quantitative Assessment of Ligand Substituent Effects on σ‐ and π‐Contributions to Fe−N Bonds in Spin Crossover Fe
II
Complexes. Chemistry 2022; 28:e202104314. [PMID: 35224791 PMCID: PMC9310619 DOI: 10.1002/chem.202104314] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2021] [Indexed: 11/24/2022]
Abstract
The effect of para‐substituent X on the electronic structure of sixteen tridentate 4‐X‐(2,6‐di(pyrazol‐1‐yl))‐pyridine (bppX) ligands and the corresponding solution spin crossover [FeII(bppX)2]2+ complexes is analysed further, to supply quantitative insights into the effect of X on the σ‐donor and π‐acceptor character of the Fe‐NA(pyridine) bonds. EDA‐NOCV on the sixteen LS complexes revealed that neither ΔEorb,σ+π (R2=0.48) nor ΔEorb,π (R2=0.31) correlated with the experimental solution T1/2 values (which are expected to reflect the ligand field imposed on the iron centre), but that ΔEorb,σ correlates well (R2=0.82) and implies that as X changes from EDG→EWG (Electron Donating to Withdrawing Group), the ligand becomes a better σ‐donor. This counter‐intuitive result was further probed by Mulliken analysis of the NA atomic orbitals: NA(px) involved in the Fe−N σ‐bond vs. the perpendicular NA(pz) employed in the ligand aromatic π‐system. As X changes EDG→EWG, the electron population on NA(pz) decreases, making it a better π‐acceptor, whilst that in NA(px) increases, making it a better σ‐bond donor; both increase ligand field, and T1/2 as observed. In 2016, Halcrow, Deeth and co‐workers proposed an intuitively reasonable explanation of the effect of the para‐X substituents on the T1/2 values in this family of complexes, consistent with the calculated MO energy levels, that M→L π‐backdonation dominates in these M−L bonds. Here the quantitative EDA‐NOCV analysis of the M−L bond contributions provides a more complete, coherent and detailed picture of the relative impact of M−L σ‐versus π‐bonding in determining the observed T1/2, refining the earlier interpretation and revealing the importance of the σ‐bonding. Furthermore, our results are in perfect agreement with the ΔE(HS‐LS) vs. σp+(X) correlation reported in their work.
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Affiliation(s)
- Luca Bondì
- Department of Chemistry MacDiarmid Institute of Advanced Materials and Nanotechnology University of Otago PO Box 56 Dunedin 9054 New Zealand
- Department of Chemistry ‘Ugo Schiff' and INSTM Research Unit University of Florence 50019 Sesto Fiorentino Italy
| | - Anna L. Garden
- Department of Chemistry MacDiarmid Institute of Advanced Materials and Nanotechnology University of Otago PO Box 56 Dunedin 9054 New Zealand
| | - Federico Totti
- Department of Chemistry ‘Ugo Schiff' and INSTM Research Unit University of Florence 50019 Sesto Fiorentino Italy
| | - Paul Jerabek
- Institute of Hydrogen Technology Helmholtz-Zentrum Hereon Max-Planck-Straße 1 21502 Geesthacht Germany
| | - Sally Brooker
- Department of Chemistry MacDiarmid Institute of Advanced Materials and Nanotechnology University of Otago PO Box 56 Dunedin 9054 New Zealand
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12
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Xie X, Li P, Xu Y, Zhou L, Yan Y, Xie L, Jia C, Guo X. Single-Molecule Junction: A Reliable Platform for Monitoring Molecular Physical and Chemical Processes. ACS NANO 2022; 16:3476-3505. [PMID: 35179354 DOI: 10.1021/acsnano.1c11433] [Citation(s) in RCA: 21] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
Monitoring and manipulating the physical and chemical behavior of single molecules is an important development direction of molecular electronics that aids in understanding the molecular world at the single-molecule level. The electrical detection platform based on single-molecule junctions can monitor physical and chemical processes at the single-molecule level with a high temporal resolution, stability, and signal-to-noise ratio. Recently, the combination of single-molecule junctions with different multimodal control systems has been widely used to explore significant physical and chemical phenomena because of its powerful monitoring and control capabilities. In this review, we focus on the applications of single-molecule junctions in monitoring molecular physical and chemical processes. The methods developed for characterizing single-molecule charge transfer and spin characteristics as well as revealing the corresponding intrinsic mechanisms are introduced. Dynamic detection and regulation of single-molecule conformational isomerization, intermolecular interactions, and chemical reactions are also discussed in detail. In addition to these dynamic investigations, this review discusses the open challenges of single-molecule detection in the fields of physics and chemistry and proposes some potential applications in this field.
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Affiliation(s)
- Xinmiao Xie
- Center for Molecular Systems and Organic Devices (CMSOD), Key Laboratory for Organic Electronics and Information Displays and Institute of Advanced Materials (IAM), Nanjing University of Posts and Telecommunications, Nanjing 210023, PR China
| | - Peihui Li
- Center of Single-Molecule Sciences, Institute of Modern Optics, Frontiers Science Center for New Organic Matter, Tianjin Key Laboratory of Micro-scale Optical Information Science and Technology, College of Electronic Information and Optical Engineering, Nankai University, 38 Tongyan Road, Jinnan District, Tianjin 300350, PR China
| | - Yanxia Xu
- Center of Single-Molecule Sciences, Institute of Modern Optics, Frontiers Science Center for New Organic Matter, Tianjin Key Laboratory of Micro-scale Optical Information Science and Technology, College of Electronic Information and Optical Engineering, Nankai University, 38 Tongyan Road, Jinnan District, Tianjin 300350, PR China
| | - Li Zhou
- Center of Single-Molecule Sciences, Institute of Modern Optics, Frontiers Science Center for New Organic Matter, Tianjin Key Laboratory of Micro-scale Optical Information Science and Technology, College of Electronic Information and Optical Engineering, Nankai University, 38 Tongyan Road, Jinnan District, Tianjin 300350, PR China
| | - Yong Yan
- Center for Molecular Systems and Organic Devices (CMSOD), Key Laboratory for Organic Electronics and Information Displays and Institute of Advanced Materials (IAM), Nanjing University of Posts and Telecommunications, Nanjing 210023, PR China
| | - Linghai Xie
- Center for Molecular Systems and Organic Devices (CMSOD), Key Laboratory for Organic Electronics and Information Displays and Institute of Advanced Materials (IAM), Nanjing University of Posts and Telecommunications, Nanjing 210023, PR China
| | - Chuancheng Jia
- Center of Single-Molecule Sciences, Institute of Modern Optics, Frontiers Science Center for New Organic Matter, Tianjin Key Laboratory of Micro-scale Optical Information Science and Technology, College of Electronic Information and Optical Engineering, Nankai University, 38 Tongyan Road, Jinnan District, Tianjin 300350, PR China
- Beijing National Laboratory for Molecular Sciences, National Biomedical Imaging Center, College of Chemistry and Molecular Engineering, Peking University, 292 Chengfu Road, Haidian District, Beijing 100871, PR China
| | - Xuefeng Guo
- Center of Single-Molecule Sciences, Institute of Modern Optics, Frontiers Science Center for New Organic Matter, Tianjin Key Laboratory of Micro-scale Optical Information Science and Technology, College of Electronic Information and Optical Engineering, Nankai University, 38 Tongyan Road, Jinnan District, Tianjin 300350, PR China
- Beijing National Laboratory for Molecular Sciences, National Biomedical Imaging Center, College of Chemistry and Molecular Engineering, Peking University, 292 Chengfu Road, Haidian District, Beijing 100871, PR China
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13
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Kumar KS, Ruben M. Sublimable Spin-Crossover Complexes: From Spin-State Switching to Molecular Devices. Angew Chem Int Ed Engl 2021; 60:7502-7521. [PMID: 31769131 PMCID: PMC8048919 DOI: 10.1002/anie.201911256] [Citation(s) in RCA: 122] [Impact Index Per Article: 40.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2019] [Indexed: 11/10/2022]
Abstract
Spin-crossover (SCO) active transition metal complexes are an important class of switchable molecular materials due to their bistable spin-state switching characteristics at or around room temperature. Vacuum-sublimable SCO complexes are a subclass of SCO complexes suitable for fabricating ultraclean spin-switchable films desirable for applications, especially in molecular electronics/spintronics. Consequently, on-surface SCO of thin-films of sublimable SCO complexes have been studied employing spectroscopy and microscopy techniques, and results of fundamental and technological importance have been obtained. This Review provides complete coverage of advances made in the field of vacuum-sublimable SCO complexes: progress made in the design and synthesis of sublimable functional SCO complexes, on-surface SCO of molecular and multilayer thick films, and various molecular and thin-film device architectures based on the sublimable SCO complexes.
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Affiliation(s)
- Kuppusamy Senthil Kumar
- Institut de Physique et Chimie des Matériaux de Strasbourg (IPCMS)CNRS-Université de Strasbourg23, rue du Loess, BP 4367034Strasbourg cedex 2France
| | - Mario Ruben
- Institut de Physique et Chimie des Matériaux de Strasbourg (IPCMS)CNRS-Université de Strasbourg23, rue du Loess, BP 4367034Strasbourg cedex 2France
- Institute of NanotechnologyKarlsruhe Institute of Technology (KIT)Hermann-von-Helmholtz-Platz 176344Eggenstein-LeopoldshafenGermany
- Institute of Quantum Materials and -TechnologyKarlsruhe Institute of Technology (KIT)Hermann-von-Helmholtz-Platz 176344Eggenstein-LeopoldshafenGermany
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14
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Kobylarczyk J, Liberka M, Stanek JJ, Sieklucka B, Podgajny R. Tuning of the phase transition between site selective SCO and intermetallic ET in trimetallic magnetic cyanido-bridged clusters. Dalton Trans 2020; 49:17321-17330. [PMID: 33206068 DOI: 10.1039/d0dt03340e] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
A series of crystalline phases composed of trimetallic 3d-5d-5d' {Fe9[Re(CN)8]6-x[W(CN)8]x(MeOH)24}·yMeOH (x = 1 (1), 2 (2), 3 (3), 4 (4) and 5 (5); y = 10-15) clusters were obtained by altering the octacyanidometalate composition. The temperature dependent studies involving SC XRD, SQUID magnetic measurements, IR spectroscopy and 57Fe Mössbauer spectroscopy revealed reversible phase transition with the retention of single crystal character in each congener. The transition was assisted by reversible spin-crossover (SCO) HSFeII↔LSFeII transition at the central Fe1(ii) site for Fe9Re5W1 (1), Fe9Re4W2 (2), Fe9Re3W3 (3) and Fe9Re2W4 (4). In contrast, the tungsten-rich congener Fe9Re1W5 (5) exhibited nontrivial behavior with the SCO transition being stopped halfway through the cooling process, to be completed with single electron transfer (ET) from the external Fe2(ii) center towards one of the neighboring W(v) sites. The critical temperature Tc of SCO has been systematically increased from 193 K (1) to 247 K (4). All experimental data indicate the domination of the Fe(ii)-W(v) valence states in all crystals 1-5, however, with increasing quantity of [W(CN)8]3- (and decreasing quantity of [Re(CN)8]3-), the valence equilibrium Fe(ii)-W(v) ↔ Fe(iii)-W(iv) was systematically shifted to the right, starting from congener 3. The overall electronic configuration at low temperatures and variable amounts and location of spin carriers along the whole series suggest the remarkable competition between magnetic super-exchange Fe(ii)-CN-W(v) interactions and intermolecular interactions. The observed behavior is in line with the information collected previously for the bimetallic congeners Fe9Re6 and Fe9W6, to shed light on the role of the mixed tri-metallic composition in changing the properties observed for the relevant bimetallic cyanido-bridged skeletons.
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Affiliation(s)
- Jedrzej Kobylarczyk
- Faculty of Chemistry, Jagiellonian University, Gronostajowa 2, 30-387 Krakow, Poland.
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15
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Dixon IM, Rat S, Sournia-Saquet A, Molnár G, Salmon L, Bousseksou A. On the Spin-State Dependence of Redox Potentials of Spin Crossover Complexes. Inorg Chem 2020; 59:18402-18406. [PMID: 33284611 DOI: 10.1021/acs.inorgchem.0c03043] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
Resistance switching properties of nanoscale junctions of spin crossover molecules have received recently much interest. In many cases, this property has been traced back to the variation of molecular orbital energies upon spin transition. However, one can also expect a substantial reorganization of the molecular structure due to charge localization, which calls for a better understanding of the relationship between the redox potential and the spin state of the molecule. To investigate this issue, we carried out a detailed density functional theory and variable temperature cyclic voltammetry investigation of the benchmark compound [Fe(HB(1,2,4-triazol-1-yl)3)2] in solution. We show that, for a correct thermodynamical picture, it is necessary to take into account the charge transfer-induced electronic and structural reorganization as well as spin equilibria in the oxidized and reduced species.
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Affiliation(s)
- Isabelle M Dixon
- Laboratoire de Chimie et Physique Quantiques, UMR 5626 CNRS/Université Toulouse 3-Paul Sabatier, Université de Toulouse, 118 route de Narbonne, 31062 Toulouse, France
| | - Sylvain Rat
- Laboratoire de Chimie de Coordination, UPR 8241, CNRS and Université de Toulouse, UPS, INP, 205 route de Narbonne, 31077 Toulouse, France
| | - Alix Sournia-Saquet
- Laboratoire de Chimie de Coordination, UPR 8241, CNRS and Université de Toulouse, UPS, INP, 205 route de Narbonne, 31077 Toulouse, France
| | - Gábor Molnár
- Laboratoire de Chimie de Coordination, UPR 8241, CNRS and Université de Toulouse, UPS, INP, 205 route de Narbonne, 31077 Toulouse, France
| | - Lionel Salmon
- Laboratoire de Chimie de Coordination, UPR 8241, CNRS and Université de Toulouse, UPS, INP, 205 route de Narbonne, 31077 Toulouse, France
| | - Azzedine Bousseksou
- Laboratoire de Chimie de Coordination, UPR 8241, CNRS and Université de Toulouse, UPS, INP, 205 route de Narbonne, 31077 Toulouse, France
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16
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Kumar KS, Ruben M. Sublimierbare Spin‐Crossover‐Komplexe: Vom Schalten des Spinzustands zu molekularen Bauelementen. Angew Chem Int Ed Engl 2020. [DOI: 10.1002/ange.201911256] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Affiliation(s)
- Kuppusamy Senthil Kumar
- Institut de Physique et Chimie des Matériaux de Strasbourg (IPCMS) CNRS-Université de Strasbourg 23, rue du Loess, BP 43 67034 Strasbourg cedex 2 Frankreich
| | - Mario Ruben
- Institut de Physique et Chimie des Matériaux de Strasbourg (IPCMS) CNRS-Université de Strasbourg 23, rue du Loess, BP 43 67034 Strasbourg cedex 2 Frankreich
- Institut für Nanotechnologie Karlsruher Institut für Technologie (KIT) Hermann-von-Helmholtz-Platz 1 76344 Eggenstein-Leopoldshafen Deutschland
- Institut für Quantenmaterialien und -technologien Karlsruher Institut für Technologie (KIT) Hermann-von-Helmholtz-Platz 1 76344 Eggenstein-Leopoldshafen Deutschland
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17
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Rabelo R, Toma L, Moliner N, Julve M, Lloret F, Pasán J, Ruiz-Pérez C, Ruiz-García R, Cano J. Electroswitching of the single-molecule magnet behaviour in an octahedral spin crossover cobalt(ii) complex with a redox-active pyridinediimine ligand. Chem Commun (Camb) 2020; 56:12242-12245. [PMID: 32926022 DOI: 10.1039/d0cc03357j] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Thermal-assisted spin crossover and field-induced slow magnetic relaxation coexist in the solid state for the mononuclear cobalt(ii) complex with the non-innocent 2,6-bis(N-4-methoxyphenylformimidoyl)pyridine ligand. One-electron oxidation of the paramagnetic low-spin CoII ion (SCo = 1/2) to the diamagnetic low-spin CoIII ion (SCo = 0) leads to the electroswitching of the slow magnetic relaxation in acetonitrile solution.
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Affiliation(s)
- Renato Rabelo
- Instituto de Ciencia Molecular (ICMol), Universitat de València, 46980 Paterna, València, Spain.
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18
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Mosey A, Dale AS, Hao G, N'Diaye A, Dowben PA, Cheng R. Quantitative Study of the Energy Changes in Voltage-Controlled Spin Crossover Molecular Thin Films. J Phys Chem Lett 2020; 11:8231-8237. [PMID: 32878433 DOI: 10.1021/acs.jpclett.0c02209] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Voltage-controlled nonvolatile isothermal spin state switching of a [Fe{H2B(pz)2}2(bipy)] (pz = tris(pyrazol-1-1y)-borohydride, bipy = 2,2'-bipyridine) film, more than 40 to 50 molecular layers thick, is possible when it is adsorbed onto a molecular ferroelectric substrate. Accompanying this high-spin and low-spin state switching, at room temperature, we observe a remarkable change in conductance, thereby allowing not only nonvolatile voltage control of the spin state ("write") but also current sensing of the molecular spin state ("read"). Monte Carlo Ising model simulations of the high-spin state occupancy, extracted from X-ray absorption spectroscopy, indicate that the energy difference between the low-spin and high-spin state is modified by 110 meV. Transport measurements demonstrate that four terminal voltage-controlled devices can be realized using this system.
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Affiliation(s)
- Aaron Mosey
- Department of Physics, Indiana University-Purdue University Indianapolis, Indianapolis, Indiana 46202, United States
| | - Ashley S Dale
- Department of Physics, Indiana University-Purdue University Indianapolis, Indianapolis, Indiana 46202, United States
| | - Guanhua Hao
- Department of Physics and Astronomy, University of Nebraska Lincoln, Lincoln, Nebraska 68588, United States
- Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States
| | - Alpha N'Diaye
- Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States
| | - Peter A Dowben
- Department of Physics and Astronomy, University of Nebraska Lincoln, Lincoln, Nebraska 68588, United States
| | - Ruihua Cheng
- Department of Physics, Indiana University-Purdue University Indianapolis, Indianapolis, Indiana 46202, United States
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19
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Anomalous Pressure Effects on the Electrical Conductivity of the Spin Crossover Complex [Fe(pyrazine){Au(CN)2}2]. MAGNETOCHEMISTRY 2020. [DOI: 10.3390/magnetochemistry6030031] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
We studied the spin-state dependence of the electrical conductivity of two nanocrystalline powder samples of the spin crossover complex [Fe(pyrazine){Au(CN)2}2]. By applying an external pressure (up to 3 kbar), we were able to tune the charge transport properties of the material from a more conductive low spin state to a crossover point toward a more conductive high spin state. We rationalize these results by taking into account the spin-state dependence of the activation parameters of the conductivity.
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20
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Cucinotta G, Poggini L, Giaconi N, Cini A, Gonidec M, Atzori M, Berretti E, Lavacchi A, Fittipaldi M, Chumakov AI, Rüffer R, Rosa P, Mannini M. Space Charge-Limited Current Transport Mechanism in Crossbar Junction Embedding Molecular Spin Crossovers. ACS APPLIED MATERIALS & INTERFACES 2020; 12:31696-31705. [PMID: 32551478 PMCID: PMC8008390 DOI: 10.1021/acsami.0c07445] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 04/22/2020] [Accepted: 06/18/2020] [Indexed: 06/11/2023]
Abstract
Spin crossover complexes are among the most studied classes of molecular switches and have attracted considerable attention for their potential technological use as active units in multifunctional devices. A fundamental step toward their practical implementation is the integration in macroscopic devices adopting hybrid vertical architectures. First, the physical properties of technological interest shown by these materials in the bulk phase have to be retained once they are deposited on a solid surface. Herein, we describe the study of a hybrid molecular inorganic junction embedding the spin crossover complex [Fe(qnal)2] (qnal = quinoline-naphthaldehyde) as an active switchable thin film sandwiched within energy-optimized metallic electrodes. In these junctions, developed and characterized with the support of state of the art techniques including synchrotron Mössbauer source (SMS) spectroscopy and focused-ion beam scanning transmission electron microscopy, we observed that the spin state conversion of the Fe(II)-based spin crossover film is associated with a transition from a space charge-limited current (SCLC) transport mechanism with shallow traps to a SCLC mechanism characterized by the presence of an exponential distribution of traps concomitant with the spin transition temperature.
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Affiliation(s)
- Giuseppe Cucinotta
- Department of Chemistry
“U. Schiff” and INSTM Research Unit, University of Florence, Via della Lastruccia 3-13, Sesto Fiorentino, FI 50019, Italy
| | - Lorenzo Poggini
- Department of Chemistry
“U. Schiff” and INSTM Research Unit, University of Florence, Via della Lastruccia 3-13, Sesto Fiorentino, FI 50019, Italy
- CNRS, University of Bordeaux, ICMCB, UMR 5026, Pessac 33600, France
| | - Niccolò Giaconi
- Department of Chemistry
“U. Schiff” and INSTM Research Unit, University of Florence, Via della Lastruccia 3-13, Sesto Fiorentino, FI 50019, Italy
| | - Alberto Cini
- Department of Physics and Astronomy and
INSTM Research Unit, University of Florence, Via Sansone 1, Sesto Fiorentino, FI 50019, Italy
| | - Mathieu Gonidec
- CNRS, University of Bordeaux, ICMCB, UMR 5026, Pessac 33600, France
| | - Matteo Atzori
- Department of Chemistry
“U. Schiff” and INSTM Research Unit, University of Florence, Via della Lastruccia 3-13, Sesto Fiorentino, FI 50019, Italy
| | - Enrico Berretti
- Institute for Chemistry of OrganoMetallic
Compounds (ICCOM-CNR), Via Madonna del Piano, Sesto Fiorentino, FI 50019, Italy
| | - Alessandro Lavacchi
- Institute for Chemistry of OrganoMetallic
Compounds (ICCOM-CNR), Via Madonna del Piano, Sesto Fiorentino, FI 50019, Italy
| | - Maria Fittipaldi
- Department of Physics and Astronomy and
INSTM Research Unit, University of Florence, Via Sansone 1, Sesto Fiorentino, FI 50019, Italy
| | | | - Rudolf Rüffer
- ESRF-The European Synchrotron, Avenue des Martyrs 71, Grenoble 38000, France
| | - Patrick Rosa
- CNRS, University of Bordeaux, ICMCB, UMR 5026, Pessac 33600, France
| | - Matteo Mannini
- Department of Chemistry
“U. Schiff” and INSTM Research Unit, University of Florence, Via della Lastruccia 3-13, Sesto Fiorentino, FI 50019, Italy
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21
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Soroceanu I, Lupu SL, Rusu I, Piedrahita-Bello M, Salmon L, Molnár G, Demont P, Bousseksou A, Rotaru A. Ligand substitution effects on the charge transport properties of the spin crossover complex [Fe(Htrz) 1+y-x (trz) 2-y (NH 2trz) x ](BF 4)y·nH 2O. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2020; 32:264002. [PMID: 32120350 DOI: 10.1088/1361-648x/ab7ba2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
The complex dielectric permittivity of a series of spin crossover complexes, with variable ligand stoichiometry [Fe(Htrz)1+y-x (trz)2-y (NH2trz) x ](BF4) y ·nH2O, has been investigated as a function of temperature in a wide frequency range. In each compound, a substantial drop of the conductivity and permittivity is evidenced when going from the low spin to the high spin state, albeit with decreasing amplitude for increasing ligand substitution (i.e. for increasing x). The deconvolution of the dielectric spectra using the Havriliak-Negami equation allowed to extract the dipole and conductivity relaxation times, their distributions as well as the dielectric strengths in both spin states. Remarkably, no clear correlation appears between the conductivity changes and the lattice properties (Debye temperature) in the dilution series. We rationalize these results by considering the dimensionality of the system (1D), wherein the charge transport occurs most likely by hopping along the [Fe(Rtrz)3] n n+ chains.
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Affiliation(s)
- Ion Soroceanu
- Faculty of Electrical Engineering and Computer Science and MANSiD Research Center, Stefan cel Mare University, Suceava, Romania
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22
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Hao G, Cheng R, Dowben PA. The emergence of the local moment molecular spin transistor. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2020; 32:234002. [PMID: 32045894 DOI: 10.1088/1361-648x/ab74e4] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Local moment molecular systems have now been used as the conduction channel in gated spintronics devices, and some of these three terminal devices might even be considered molecular spin transistors. In these systems, the gate voltage can be used to tune the molecular level alignment, while applied magnetic fields have an influence on the spin state, altering the magnetic properties, and providing insights to the magnetic anisotropy. More recently, the use of molecular spin crossover complexes, as the conduction channel, has led to devices that are both nonvolatile and have functionality at higher temperatures. Indeed, some devices have now been demonstrated to work at room temperature. Here, several molecular transistors, including those claiming to use single molecule magnets (SMM), are reviewed.
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Affiliation(s)
- Guanhua Hao
- Department of Physics and Astronomy, University of Nebraska, Lincoln, NE, 68588-0299, United States of America
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23
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Ostrovsky SM, Klokishner SI. Modeling of Electron Transfer in a Linear Trinuclear Fe-Co-Fe Complex: Magnetic and Polarizability Properties. J Phys Chem A 2020; 124:3618-3625. [PMID: 32279495 DOI: 10.1021/acs.jpca.0c01717] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
A microscopic approach to the problem of charge transfer-induced spin transitions in a system of interacting trinuclear Fe-Co-Fe clusters, which takes into account the switching of polarization during the transformation FelsII-ColsIII-FelsIII→ FelsIII-CohsII-FelsIII (ls-low spin, hs-high spin), has been developed. The cooperative electron-deformational and dipole-dipole interactions and the intracluster electron transfer have been proved to govern the observed significant changes in the magnetic and polarization characteristics of the examined system. The role of intra- and intercluster interactions in the spin transformation has been elucidated. On the basis of the developed approach, an explanation of the temperature dependence of the magnetic susceptibility and of the polar-nonpolar transformation in the {[FeTp(CN)3]2Co(Meim)4}·6H2O compound in response to thermal stimuli has been given.
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Affiliation(s)
- S M Ostrovsky
- Institute of Applied Physics, Chisinau MD-2028, Moldova
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24
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Usmani S, Mikolasek M, Gillet A, Sanchez Costa J, Rigoulet M, Chaudret B, Bousseksou A, Lassalle-Kaiser B, Demont P, Molnár G, Salmon L, Carrey J, Tricard S. Spin crossover in Fe(triazole)-Pt nanoparticle self-assembly structured at the sub-5 nm scale. NANOSCALE 2020; 12:8180-8187. [PMID: 32248213 DOI: 10.1039/d0nr02154g] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
A main goal of molecular electronics is to relate the performance of devices to the structure and electronic state of molecules. Among the variety of possibilities that organic, organometallic and coordination chemistries offer to tune the energy levels of molecular components, spin crossover phenomenon is a perfect candidate for elaboration of molecular switches. The reorganization of the electronic state population of the molecules associated to the spin crossover can indeed lead to a significant change in conductivity. However, molecular spin crossover is very sensitive to the environment and can disappear once the molecules are integrated into devices. Here, we show that the association of ultra-small 1.2 nm platinum nanoparticles with FeII triazole-based spin crossover coordination polymers leads to self-assemblies, extremely well organized at the sub-3 nm scale. The quasi-perfect alignment of nanoparticles observed by transmission electron microscopy, in addition to specific signature in infrared spectroscopy, demonstrates the coordination of the long-chain molecules with the nanoparticles. Spin crossover is confirmed in such assemblies by X-ray absorption spectroscopic measurements and shows unambiguous characteristics both in magnetic and charge transport measurements. Coordinating polymers are therefore ideal candidates for the elaboration of robust, well-organized, hybrid self-assemblies with metallic nanoparticles, while maintaining sensitive functional properties, such as spin crossover.
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Affiliation(s)
- Suhail Usmani
- Laboratoire de Physique et Chimie des Nano-Objets, INSA, CNRS, Université de Toulouse, Toulouse, France.
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25
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Kobylarczyk J, Liberka M, Konieczny P, Baran S, Kubicki M, Korzeniak T, Podgajny R. Bulky ligands shape the separation between the large spin carriers to condition field-induced slow magnetic relaxation. Dalton Trans 2020; 49:300-311. [PMID: 31774091 DOI: 10.1039/c9dt03903a] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Crystal engineering of magnetic relaxation in supramolecular networks based on almost isotropic cyanido-bridged {Mn9[W(CN)8]6L8(solv)8} clusters decorated by bulky 4,4'-di-tert-butyl-2,2'-bipyridine (But2bpy) and 4,7-diphenyl-1,10-phenanthroline (Ph2phen) ligands is presented. The three new compounds {MnII9[WV(CN)8]6(But2bpy)8(MeOH)8}·Pri2O·13MeOH (1), {MnII9[WV(CN)8]6(But2bpy)8(MeOH)6(H2O)2}·4Pri2O·2H2O (1a), and {MnII9[WV(CN)8]6(Ph2phen)8(MeOH)8}·29MeOH·6H2O (2) were characterized structurally and magnetically. Compound 1 exhibits unequivocal domination of repulsive intercluster contacts operating between the side But groups leading to intercluster distances exceeding 10 Å in all three dimensions. Compound 1a reveals a 1-dimensional (1D) supramolecular chain structure with very close intercluster distances of 6.7 Å realized through the direct W-CNHO-Mn hydrogen bonds along the chain, further isolated by the above repulsive ButBut synthons. Compound 2 shows significant separation in all three directions with the intercluster distances close to 10, 12 and 13.5 Å. However, in contrast to 1, these separations are accompanied by indirect hydrogen bond arrays and local π-π interactions of potential to assist in the transfer of weak magnetic interactions. The dc magnetic data show the signature of S = 39/2 in the ground state, which is typical in this group of compounds. The high-spin clusters are accompanied by different intercluster interactions, illustrated by the effective zJ' values of +0.010 cm-1 (1), +0.008 cm-1 (1a) and +0.001 cm-1 (2). The low temperature ac susceptibility measurements revealed a temperature- and field-dependent magnetic relaxation time for all 1, 1a and 2 compounds (τ1, τ1a-fast, and τ2-fast in the range 10-3-10-4 s). In contrast and only in the case of 1a and 2, an additional temperature independent slow process was detected (τ1a-slow and τ2-slow located between 0.1 s and 1 s). The magnetic relaxations were correlated with the obtained supramolecular networks, indicating the significant role of dipolar fields, weak non-covalent interactions, hydrogen bonds and π-π interactions.
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Affiliation(s)
- Jedrzej Kobylarczyk
- Faculty of Chemistry, Jagiellonian University, Gronostajowa 2, 30-387 Kraków, Poland.
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Senthil Kumar K, Vela S, Heinrich B, Suryadevara N, Karmazin L, Bailly C, Ruben M. Bi-stable spin-crossover in charge-neutral [Fe(R-ptp) 2] (ptp = 2-(1H-pyrazol-1-yl)-6-(1H-tetrazol-5-yl)pyridine) complexes. Dalton Trans 2019; 49:1022-1031. [PMID: 31859300 DOI: 10.1039/c9dt04411f] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Bi-stable charge-neutral iron(ii) spin-crossover (SCO) complexes are a class of switchable molecular materials proposed for molecule-based switching and memory applications. In this study, we report on the SCO behavior of a series of iron(ii) complexes composed of rationally designed 2-(1H-pyrazol-1-yl)-6-(1H-tetrazol-5-yl)pyridine (ptp) ligands. The powder forms of [Fe2+(R-ptp-)2]0 complexes tethered with less-bulky substituents-R = H (1), R = CH2OH (2), and R = COOCH3 (3; previously reported)-at the 4-position of the pyridine ring of the ptp skeleton showed abrupt and hysteretic SCO at or above room temperature (RT), whereas complex 5 featuring a bulky pyrene substituent showed incomplete and gradual SCO behavior. The role of intermolecular interactions, lattice solvent, and electronic nature of the chemical substituents (R) in tuning the SCO of the complexes is elucidated.
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Affiliation(s)
- Kuppusamy Senthil Kumar
- Institut de Physique et Chimie des Matériaux de Strasbourg (IPCMS), CNRS-Université de Strasbourg, 23, rue du Loess, BP 43, 67034 Strasbourg Cedex 2, France.
| | - Sergi Vela
- Laboratoire de Chimie Quantique, Institut de Chimie, UMR 7177 CNRS-Université de Strasbourg, 4 rue Blaise Pascal, 67081 Strasbourg, France.
| | - Benoît Heinrich
- Institut de Physique et Chimie des Matériaux de Strasbourg (IPCMS), CNRS-Université de Strasbourg, 23, rue du Loess, BP 43, 67034 Strasbourg Cedex 2, France.
| | - Nithin Suryadevara
- Institute of Nanotechnology (INT), Karlsruhe Institute of Technology (KIT), Hermann-von-Helmholtz-Platz 1, 76344, Eggenstein-Leopoldshafen, Germany.
| | - Lydia Karmazin
- Service de Radiocristallographie, Fédération de Chimie Le Bel, FR2010 CNRS-Université de Strasbourg, 1 rue Blaise Pascal, BP 296/R8, 67008 Strasbourg Cedex, France
| | - Corinne Bailly
- Service de Radiocristallographie, Fédération de Chimie Le Bel, FR2010 CNRS-Université de Strasbourg, 1 rue Blaise Pascal, BP 296/R8, 67008 Strasbourg Cedex, France
| | - Mario Ruben
- Institut de Physique et Chimie des Matériaux de Strasbourg (IPCMS), CNRS-Université de Strasbourg, 23, rue du Loess, BP 43, 67034 Strasbourg Cedex 2, France. and Institute of Nanotechnology (INT), Karlsruhe Institute of Technology (KIT), Hermann-von-Helmholtz-Platz 1, 76344, Eggenstein-Leopoldshafen, Germany.
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Soroceanu I, Graur A, Coca E, Salmon L, Molnar G, Demont P, Bousseksou A, Rotaru A. Broad-Band Dielectric Spectroscopy Reveals Peak Values of Conductivity and Permittivity Switching upon Spin Crossover. J Phys Chem Lett 2019; 10:7391-7396. [PMID: 31714791 DOI: 10.1021/acs.jpclett.9b02678] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
We use broad-band dielectric spectroscopy to investigate the spin-state dependence of electrical properties of the [Fe(Htrz)2(trz)](BF4) spin crossover complex. We show that the Havriliak-Negami theory can fully describe the variation of the complex dielectric permittivity of the material across the pressure-temperature phase diagram. The analysis reveals three dielectric relaxation processes, which we attribute to electrode/interface polarization, dipole relaxation, and charge transport relaxation. The contribution of the latter appears significant to the dielectric strength. Remarkably, the permittivity and conductivity changes between the high spin and low spin states are amplified at the corresponding relaxation frequencies.
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Affiliation(s)
- Ion Soroceanu
- Faculty of Electrical Engineering and Computer Science and MANSiD Research Center , Stefan cel Mare University , 13, Strada Universitatii , Suceava 720229 , Romania
| | - Adrian Graur
- Faculty of Electrical Engineering and Computer Science and MANSiD Research Center , Stefan cel Mare University , 13, Strada Universitatii , Suceava 720229 , Romania
| | - Eugen Coca
- Faculty of Electrical Engineering and Computer Science and MANSiD Research Center , Stefan cel Mare University , 13, Strada Universitatii , Suceava 720229 , Romania
| | - Lionel Salmon
- LCC, CNRS and Université de Toulouse , F-31077 Toulouse , France
| | - Gabor Molnar
- LCC, CNRS and Université de Toulouse , F-31077 Toulouse , France
| | - Philippe Demont
- CIRIMAT, CNRS and Université de Toulouse , F-31068 Toulouse , France
| | | | - Aurelian Rotaru
- Faculty of Electrical Engineering and Computer Science and MANSiD Research Center , Stefan cel Mare University , 13, Strada Universitatii , Suceava 720229 , Romania
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Jiang X, Hao G, Wang X, Mosey A, Zhang X, Yu L, Yost AJ, Zhang X, DiChiara AD, N'Diaye AT, Cheng X, Zhang J, Cheng R, Xu X, Dowben PA. Tunable spin-state bistability in a spin crossover molecular complex. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2019; 31:315401. [PMID: 30995634 DOI: 10.1088/1361-648x/ab1a7d] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
The spin crossover (SCO) transitions at both the surface and over the entire volume of the [Fe{H2B(pz)2}2(bipy)] polycrystalline films on Al2O3 substrates have been studied, where pz = pyrazol-1-yl and bipy = 2,2'-bipyridine. For [Fe{H2B(pz)2}2(bipy)] films of hundreds of nm thick, magnetometry and x-ray absorption spectroscopy measurements show thermal hysteresis in the SCO transition with temperature, although the transition in bulk [Fe{H2B(pz)2}2(bipy)] occurs in a non-hysteretic fashion at 157 K. While the size of the crystallites in those films are similar, the hysteresis becomes more prominent in thinner films, indicating a significant effect of the [Fe{H2B(pz)2}2(bipy)]/Al2O3 interface. Bistability of spin states, which can be inferred from the thermal hysteresis, was directly observed using temperature-dependent x-ray diffraction; the crystallites behave as spin-state domains that coexist during the transition. The difference between the spin state of molecules at the surface of the [Fe{H2B(pz)2}2(bipy)] films and that of the molecules within the films, during the thermal cycle, indicates that both cooperative (intermolecular) effects and coordination are implicated in perturbations to the SCO transition.
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Affiliation(s)
- Xuanyuan Jiang
- Department of Physics and Astronomy, University of Nebraska, Lincoln, NE 68588, United States of America
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29
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Kitagawa Y, Tada H, Era I, Fujii T, Ikenaga K, Nakano M. Theoretical Study on the Difference in Electron Conductivity of a One-Dimensional Penta-Nickel(II) Complex between Anti-Ferromagnetic and Ferromagnetic States-Possibility of Molecular Switch with Open-Shell Molecules. Molecules 2019; 24:molecules24101956. [PMID: 31117287 PMCID: PMC6571866 DOI: 10.3390/molecules24101956] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2019] [Revised: 05/16/2019] [Accepted: 05/17/2019] [Indexed: 11/21/2022] Open
Abstract
The electron conductivity of an extended metal atom chain (EMAC) that consisted of penta-nickel(II) ions bridged by oligo-α-pyridylamino ligands was examined by density functional theory (DFT) and elastic scattering Green’s functions (ESGF) calculations. The calculated results revealed that an intramolecular ferromagnetic (FM) coupling state showed a higher conductivity in comparison with an anti-ferromagnetic (AFM) coupling state. The present results suggest the potential of the complex as a molecular switch as well as a molecular wire.
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Affiliation(s)
- Yasutaka Kitagawa
- Department of Materials Engineering Science, Graduate School of Engineering Science, Osaka University, Toyonaka, Osaka 560-8531, Japan.
- Center for Spintronics Research Network (CSRN), Graduate School of Engineering Science, Osaka University, Toyonaka, Osaka 560-8531, Japan.
| | - Hayato Tada
- Department of Materials Engineering Science, Graduate School of Engineering Science, Osaka University, Toyonaka, Osaka 560-8531, Japan.
| | - Iori Era
- Department of Materials Engineering Science, Graduate School of Engineering Science, Osaka University, Toyonaka, Osaka 560-8531, Japan.
| | - Takuya Fujii
- Department of Materials Engineering Science, Graduate School of Engineering Science, Osaka University, Toyonaka, Osaka 560-8531, Japan.
| | - Kazuki Ikenaga
- Department of Materials Engineering Science, Graduate School of Engineering Science, Osaka University, Toyonaka, Osaka 560-8531, Japan.
| | - Masayoshi Nakano
- Department of Materials Engineering Science, Graduate School of Engineering Science, Osaka University, Toyonaka, Osaka 560-8531, Japan.
- Center for Spintronics Research Network (CSRN), Graduate School of Engineering Science, Osaka University, Toyonaka, Osaka 560-8531, Japan.
- Quantum Information and Quantum Biology Division, Institute for Open and Transdisciplinary Research Initiatives, Osaka University, Toyonaka, Osaka 560-8531, Japan.
- Institute for Molecular Science, 38 Nishigo-Naka, Myodaiji, Okazaki 444-8585, Japan.
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Saiki R, Miyamoto H, Sagayama H, Kumai R, Newton GN, Shiga T, Oshio H. Substituent dependence on the spin crossover behaviour of mononuclear Fe(ii) complexes with asymmetric tridentate ligands. Dalton Trans 2019; 48:3231-3236. [PMID: 30720038 DOI: 10.1039/c9dt00204a] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Three mononuclear iron(ii) complexes of the formula [FeII(H2L1-3)2](BF4)2·x(solv.) (H2L1-3 = 2-[5-(R-phenyl)-1H-pyrazole-3-yl] 6-benzimidazole pyridine; H2L1: R = 4-methylphenyl, H2L2, R = 2,4,6-trimethylphenyl, H2L3, R = 2,3,4,5,6-pentamethylphenyl) (1, H2L1; 2, H2L2; 3, H2L3) with asymmetric tridentate ligands (H2L1-3) were synthesized and their structures and magnetic behaviour investigated. Significant structural distortions of the dihedral angles between phenyl and pyrazole groups were observed and found to depend on the nature of the substituent groups. Cryomagnetic studies reveal that 1 and 2 show gradual spin crossover behavior, while 3 remains in the high spin state between 1.8 and 300 K.
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Affiliation(s)
- Ryo Saiki
- Graduate School of Pure and Applied Sciences, University of Tsukuba, Tennodai 1-1-1, Tsukuba, Ibaraki 305-8571, Japan.
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31
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Baldé C, Sylla MS, Desplanches C, Chastanet G. High-spin → low-spin relaxation kinetics and metal dilution effects in 1D spin-crossover chain compounds. Polyhedron 2019. [DOI: 10.1016/j.poly.2018.11.046] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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32
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Vela S, Paulsen H. Deciphering crystal packing effects in the spin crossover of six [FeII(2-pic)3]Cl2 solvatomorphs. Dalton Trans 2019; 48:1237-1245. [DOI: 10.1039/c8dt04394a] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
Six isostructural solvatomorphs of the same Fe(ii) complex have been reported to display completely different SCO transitions due to tiny differences in their crystal environments. In this paper, we unravel the reasons.
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Affiliation(s)
- Sergi Vela
- Laboratoire de Chimie Quantique
- UMR 7111
- CNRS-Université de Strasbourg
- F-67000 Strasbourg
- France
| | - Hauke Paulsen
- Institut für Physik
- Universität zu Lübeck
- D-23562 Lübeck
- Germany
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34
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Shiga T, Sato Y, Tachibana M, Sato H, Matsumoto T, Sagayama H, Kumai R, Murakami Y, Newton GN, Oshio H. Carboxylic Acid Functionalized Spin-Crossover Iron(II) Grids for Tunable Switching and Hybrid Electrode Fabrication. Inorg Chem 2018; 57:14013-14017. [PMID: 30379073 DOI: 10.1021/acs.inorgchem.8b01856] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Two carboxyl-substituted iron(II) grids, one protonated, [Fe4(HL)4](BF4)4·4MeCN·AcOEt (1), and the other deprotonated, [Fe4(L)4]·DMSO·EtOH (2), where H2L = 4-{4,5-bis[6-(3,5-dimethylpyrazol-1-yl)pyrid-2-yl]-1 H-imidazol-2-yl}benzoic acid, were synthesized. Single-crystal X-ray structure analyses reveal that both complexes have a tetranuclear [2 × 2] grid structure. 1 formed one-dimensional chains through intermolecular hydrogen bonds between the carboxylic acid units of neighboring grids, while 2 formed two-dimensional layers stabilized by π-π-stacking interactions. 1 showed spin transition between the 3HS-1LS and 1.5HS-2.5LS states around 200 K, while 2 showed spin-crossover between the 4LS and 2LS-2HS states above 300 K. A modified indium-tin oxide (ITO) electrode was fabricated by soaking the ITO in a solution of 1. The resultant electrode showed reversible redox waves attributed to the original redox processes of iron(II)/iron(III).
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Affiliation(s)
- Takuya Shiga
- Graduate School of Pure and Applied Sciences , University of Tsukuba , Tennodai 1-1-1 , Tsukuba , Ibaraki 305-8571 , Japan
| | - Yamato Sato
- Graduate School of Pure and Applied Sciences , University of Tsukuba , Tennodai 1-1-1 , Tsukuba , Ibaraki 305-8571 , Japan
| | - Minami Tachibana
- Graduate School of Pure and Applied Sciences , University of Tsukuba , Tennodai 1-1-1 , Tsukuba , Ibaraki 305-8571 , Japan
| | - Hiroki Sato
- Graduate School of Pure and Applied Sciences , University of Tsukuba , Tennodai 1-1-1 , Tsukuba , Ibaraki 305-8571 , Japan
| | - Takuto Matsumoto
- Graduate School of Pure and Applied Sciences , University of Tsukuba , Tennodai 1-1-1 , Tsukuba , Ibaraki 305-8571 , Japan
| | - Hajime Sagayama
- Photon Factory and Condensed Matter Research Center, Institute of Materials Structure Science , High Energy Accelerator Research Organization , Oho 1-1 , Tsukuba , Ibaraki 305-0801 , Japan
| | - Reiji Kumai
- Photon Factory and Condensed Matter Research Center, Institute of Materials Structure Science , High Energy Accelerator Research Organization , Oho 1-1 , Tsukuba , Ibaraki 305-0801 , Japan
| | - Youichi Murakami
- Photon Factory and Condensed Matter Research Center, Institute of Materials Structure Science , High Energy Accelerator Research Organization , Oho 1-1 , Tsukuba , Ibaraki 305-0801 , Japan
| | - Graham N Newton
- GSK Carbon Neutral Laboratories for Sustainable Chemistry , The University of Nottingham , Nottingham NG7 2TU , U.K
| | - Hiroki Oshio
- Graduate School of Pure and Applied Sciences , University of Tsukuba , Tennodai 1-1-1 , Tsukuba , Ibaraki 305-8571 , Japan
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Cirera J, Via-Nadal M, Ruiz E. Benchmarking Density Functional Methods for Calculation of State Energies of First Row Spin-Crossover Molecules. Inorg Chem 2018; 57:14097-14105. [DOI: 10.1021/acs.inorgchem.8b01821] [Citation(s) in RCA: 90] [Impact Index Per Article: 15.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Affiliation(s)
- Jordi Cirera
- Departament de Química Inorgànica i Orgànica and Institut de Recerca de Química Teòrica i Computacional, Universitat de Barcelona, Diagonal 645, 08028 Barcelona, Spain
| | - Mireia Via-Nadal
- Departament de Química Inorgànica i Orgànica and Institut de Recerca de Química Teòrica i Computacional, Universitat de Barcelona, Diagonal 645, 08028 Barcelona, Spain
| | - Eliseo Ruiz
- Departament de Química Inorgànica i Orgànica and Institut de Recerca de Química Teòrica i Computacional, Universitat de Barcelona, Diagonal 645, 08028 Barcelona, Spain
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Vela S, Paulsen H. Cooperativity in Spin Crossover Systems. An Atomistic Perspective on the Devil's Staircase. Inorg Chem 2018; 57:9478-9488. [PMID: 30040398 DOI: 10.1021/acs.inorgchem.8b01463] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Cooperativity is key in defining the shape (i.e., gradual, abrupt, or hysteretic) of thermally driven spin transitions in magnetic switches. Despite its importance, there is very little information on its atomistic origin, which hinders the rational design of materials displaying a bistability region (i.e., hysteresis). In this paper, we investigate the spin transition of two solvatomorphs of [Fe(2-pic)3]Cl2, an Fe(II)-complex displaying thermal spin crossover (SCO) from a low-spin (LS) to a high-spin (HS) state with either gradual or abrupt two-step character. To do it, we apply a novel computational protocol to study the cooperativity of SCO compounds from DFT calculations, which does not rely on a priori assumptions on the studied system. The distinct shape of the spin transition is successfully captured, and the atomistic origin of cooperativity is traced back to geometrical distortions of the Fe-N6 core in case of the solvatomorph exhibiting an abrupt transition. According to our calculations, HS and LS molecules contribute differently to cooperativity, which results in a complex energetic evolution of the spin transition that cannot be described by the common Slichter-Drickamer model. The present work opens new avenues for the study of cooperativity of SCO systems having a chemically oriented perspective and demonstrates that quantum chemistry calculations can discriminate the shape of a spin transition, while providing insight into the atomistic underlying factors that contribute to its cooperative behavior.
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Affiliation(s)
- Sergi Vela
- Laboratoire de Chimie Quantique, UMR 7111 , CNRS-Université de Strasbourg , 4 rue Blaise Pascal , F-67000 Strasbourg , France
| | - Hauke Paulsen
- Institut für Physik , Universität zu Lübeck , Ratzeburger Allee 160 , D-23562 Lübeck , Germany
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Vela S, Verot M, Fromager E, Robert V. Electron transport through a spin crossover junction. Perspectives from a wavefunction-based approach. J Chem Phys 2018; 146:064112. [PMID: 28201891 DOI: 10.1063/1.4975327] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
The present paper reports the application of a computational framework, based on the quantum master equation, the Fermi's golden Rule, and conventional wavefunction-based methods, to describe electron transport through a spin crossover molecular junction (Fe(bapbpy) (NCS)2, 1, bapbpy = N-(6-(6-(Pyridin-2-ylamino)pyridin-2-yl)pyridin-2-yl)-pyridin-2-amine). This scheme is an alternative to the standard approaches based on the relative position and nature of the frontier orbitals, as it evaluates the junction's Green's function by means of accurate state energies and wavefunctions. In the present work, those elements are calculated for the relevant states of the high- and low-spin species of 1, and they are used to evaluate the output conductance within a given range of bias- and gate-voltages. The contribution of the ground and low-lying excited states to the current is analyzed, and inspected in terms of their 2S + 1 Ms-states. In doing so, it is shown the relevance of treating not only the ground state in its maximum-Ms projection, as usually done in most computational-chemistry packages, but the whole spectrum of low-energy states of the molecule. Such improved representation of the junction has a notable impact on the total conductivity and, more importantly, it restores the equivalence between alpha and beta transport, which means that no spin polarization is observed in the absence of Zeeman splitting. Finally, this work inspects the strong- and weak-points of the suggested theoretical framework to understand electron transport through molecular switchable materials, identifies a pathway for future improvement, and offers a new insight into concepts that play a key role in spintronics.
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Affiliation(s)
- Sergi Vela
- Laboratoire de Chimie Quantique, UMR 7177, CNRS-Université de Strasbourg, 4 rue Blaise Pascal, F-67000 Strasbourg, France
| | - Martin Verot
- Laboratoire de Chimie, École Normale Supérieure de Lyon, CNRS, 46 allée d'Italie, F-69364 Lyon, France
| | - Emmanuel Fromager
- Laboratoire de Chimie Quantique, UMR 7177, CNRS-Université de Strasbourg, 4 rue Blaise Pascal, F-67000 Strasbourg, France
| | - Vincent Robert
- Laboratoire de Chimie Quantique, UMR 7177, CNRS-Université de Strasbourg, 4 rue Blaise Pascal, F-67000 Strasbourg, France
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Baldé C, Paradis N, Desplanches C, Chastanet G. Switchable Heteroleptic Mononuclear Iron(II) Complexes as Versatile Molecular Building Block. Eur J Inorg Chem 2018. [DOI: 10.1002/ejic.201800053] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Affiliation(s)
- Chérif Baldé
- Laboratoire de Chimie et Physique des Matériaux (LCPM) Université Assane Seck de Ziguinchor 523 Ziguinchor Sénégal
| | - Nicolas Paradis
- CNRS Université de Bordeaux ICMCB 87 avenue du Dr. A. Schweitzer 33608 Pessac France
| | - Cédric Desplanches
- CNRS Université de Bordeaux ICMCB 87 avenue du Dr. A. Schweitzer 33608 Pessac France
| | - Guillaume Chastanet
- CNRS Université de Bordeaux ICMCB 87 avenue du Dr. A. Schweitzer 33608 Pessac France
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Slusarski T, Kostyrko T, García-Suárez VM. Effects of acceptor doping on a metalorganic switch: DFT vs. model analysis. Phys Chem Chem Phys 2018; 20:13588-13597. [PMID: 29736537 DOI: 10.1039/c8cp01283k] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
We propose a molecular switch based on copper dioxolene molecules with valence tautomeric properties. We study the system using density functional theory and a model Hamiltonian that can properly account for electronic correlations in these complex molecular systems. We compute the transport properties of the junction with a Cu-dioxolene unit sandwiched between gold electrodes and analyze its dependence on the valence tautomeric state of the molecule. We also study the effects of doping with ICl2 acceptor molecules on the magnetic and electronic features of the device. We find that in the absence of dopants, the Cu-dioxolene unit is weakly charged in a S = 1/2 spin state. However, the acceptors increase the charge state of the molecule and make possible a transition between the high-spin (S = 1) triplet and the low-spin (S = 0) singlet. The I-V dependence shows a manifestation of spin filtering and a voltage-induced multistable behavior that can have several applications in nanoscale electronic devices.
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Affiliation(s)
- Tomasz Slusarski
- Faculty of Chemistry, A. Mickiewicz University, ul. Umultowska 89b, 61-614 Poznań, Poland
| | - Tomasz Kostyrko
- Faculty of Physics, A. Mickiewicz University, ul. Umultowska 85, 61-614 Poznań, Poland.
| | - V M García-Suárez
- Departamento de Física, Universidad de Oviedo, 33007 Oviedo, Spain and Nanomaterials and Nanotechnology Research Center (CINN), Oviedo, Spain
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Siig OS, Kepp KP. Iron(II) and Iron(III) Spin Crossover: Toward an Optimal Density Functional. J Phys Chem A 2018; 122:4208-4217. [PMID: 29630380 DOI: 10.1021/acs.jpca.8b02027] [Citation(s) in RCA: 63] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
Spin crossover (SCO) plays a major role in biochemistry, catalysis, materials, and emerging technologies such as molecular electronics and sensors, and thus accurate prediction and design of SCO systems is of high priority. However, the main tool for this purpose, density functional theory (DFT), is very sensitive to applied methodology. The most abundant SCO systems are Fe(II) and Fe(III) systems. Even with average good agreement, a functional may be significantly more accurate for Fe(II) or Fe(III) systems, preventing balanced study of SCO candidates of both types. The present work investigates DFT's performance for well-known Fe(II) and Fe(III) SCO complexes, using various design types and customized versions of GGA, hybrid, meta-GGA, meta-hybrid, double-hybrid, and long-range-corrected hybrid functionals. We explore the limits of DFT performance and identify proficient Fe(II)-Fe(III)-balanced functionals. We identify and quantify remarkable differences in the DFT description of Fe(II) and Fe(III) systems. Most functionals become more accurate once Hartree-Fock exchange is adjusted to 10-17%, regardless of the type of functionals involved. However, this typically introduces a clear Fe(II)-Fe(III) bias. The most accurate functionals measured by mean absolute errors <10 kJ/mol are CAMB3LYP-17, B3LYP*, and B97-15 with 15-17% Hartree-Fock exchange, closely followed by CAMB3LYP and CAMB3LYP-15, OPBE, rPBE-10, and B3P86-15. While GGA functionals display a small Fe(II)-Fe(III) bias, they are generally inaccurate, except the O exchange functional. Hybrid functionals (including B2PLYP double hybrids and meta hybrids) tend to favor HS too much in Fe(II) vs Fe(III), which is important in many studies where the oxidation state of iron can vary, e.g. rational SCO design and studies of catalytic processes involving iron. The only functional with a combined bias <5 kJ/mol and a decent MAE (15 kJ/mol) is our customized PBE0-12 functional. Alternatively one has to sacrifice Fe(II)-Fe(III) balance to use the best functionals for each group separately. We also investigated the precision (measured as the standard deviation of errors) and show that the target accuracy for iron SCO is 10 kJ/mol for accuracy and 5 kJ/mol for precision, and DFT is probably not going to break this limit in the near future. Importantly, all four types of functional behavior (accurate/precise, accurate/imprecise, inaccurate/precise, inaccurate/imprecise) are observed. More generally, our work illustrates the importance not only of overall accuracy but also of balanced accuracy for systems likely to occur in context.
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Affiliation(s)
- Oliver S Siig
- DTU Chemistry , Technical University of Denmark , Building 206 , 2800 Kgs. Lyngby , Denmark
| | - Kasper P Kepp
- DTU Chemistry , Technical University of Denmark , Building 206 , 2800 Kgs. Lyngby , Denmark
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41
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Wen Z, Zhou L, Cheng JF, Li SJ, You WL, Wang X. Spin crossover and high spin filtering behavior in Co-Pyridine and Co-Pyrimidine molecules. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2018; 30:105301. [PMID: 29447124 DOI: 10.1088/1361-648x/aaab7c] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
We present a theoretical study on a series of cobalt complexes, which are constructed with cobalt atoms and pyridine/pyrimidine rings, using density functional theory. We investigate the structural and electric transport properties of spin crossover (SCO) Co complex with two spin states, namely low-spin configuration [LS] and high-spin configuration [HS]. Energy analyses of the two spin states imply that the SCO Co-Pyridine2 and Co-Pyrimidine2 complexes may display a spin transition process accompanied by a geometric modification driven by external stimuli. A nearly perfect spin filtering effect is observed in the Co-Pyrimidine2 complex with [HS] state. In addition, we also discover the contact-dependent transmission properties of Co-Pyridine2. These findings indicate that SCO Co complexes are promising materials for molecular spintronic devices.
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Affiliation(s)
- Zhongqian Wen
- College of Physics, Optoelectronics and Energy, Soochow University, Suzhou 215006, People's Republic of China
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42
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Karan S, García C, Karolak M, Jacob D, Lorente N, Berndt R. Spin Control Induced by Molecular Charging in a Transport Junction. NANO LETTERS 2018; 18:88-93. [PMID: 29232947 DOI: 10.1021/acs.nanolett.7b03411] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
The ability of molecules to maintain magnetic multistability in nanoscale-junctions will determine their role in downsizing spintronic devices. While spin-injection from ferromagnetic leads gives rise to magnetoresistance in metallic nanocontacts, nonmagnetic leads probing the magnetic states of the junction itself have been considered as an alternative. Extending this experimental approach to molecular junctions, which are sensitive to chemical parameters, we demonstrate that the electron affinity of a molecule decisively influences its spin transport. We use a scanning tunneling microscope to trap a meso-substituted iron porphyrin, putting the iron center in an environment that provides control of its charge and spin states. A large electron affinity of peripheral ligands is shown to enable switching of the molecular S = 1 ground state found at low electron density to S = 1/2 at high density, while lower affinity keeps the molecule inactive to spin-state transition. These results pave the way for spin control using chemical design and electrical means.
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Affiliation(s)
- Sujoy Karan
- Institut für Experimentelle und Angewandte Physik, Christian-Albrechts-Universität zu Kiel , 24098 Kiel, Germany
- Institute of Experimental and Applied Physics, University of Regensburg , 93053 Regensburg, Germany
| | - Carlos García
- Donostia International Physics Center (DIPC), Paseo Manuel de Lardizabal 4, 20018 Donostia-San Sebastián, Spain
| | - Michael Karolak
- Institut für Theoretische Physik und Astrophysik, Universität Würzburg , Am Hubland, 97074 Würzburg, Germany
| | - David Jacob
- Departamento de Física de Materiales, Universidad del País Vasco, UPV/EHU , Av. Tolosa 72, 20018 San Sebastián, Spain
- IKERBASQUE, Basque Foundation for Science, Maria Diaz de Haro 3, 48013 Bilbao, Spain
| | - Nicolás Lorente
- Donostia International Physics Center (DIPC), Paseo Manuel de Lardizabal 4, 20018 Donostia-San Sebastián, Spain
- Centro de Física de Materiales CFM/MPC, CSIC-UPV/EHU , Paseo Manuel de Lardizabal 5, 20018 Donostia-San Sebastián, Spain
| | - Richard Berndt
- Institut für Experimentelle und Angewandte Physik, Christian-Albrechts-Universität zu Kiel , 24098 Kiel, Germany
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43
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Zhang X, N'Diaye AT, Jiang X, Zhang X, Yin Y, Chen X, Hong X, Xu X, Dowben PA. Indications of magnetic coupling effects in spin cross-over molecular thin films. Chem Commun (Camb) 2018; 54:944-947. [DOI: 10.1039/c7cc08246k] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Room temperature isothermal reversible spin crossover switching of [Fe(H2B(pz)2)2(bipy)] thin films by external magnetic fields is demonstrated.
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Affiliation(s)
- Xin Zhang
- Department of Physics and Astronomy
- University of Nebraska
- Lincoln
- USA
| | - Alpha T. N'Diaye
- Advanced Light Source
- Lawrence Berkeley National Laboratory
- Berkeley
- USA
| | - Xuanyuan Jiang
- Department of Physics and Astronomy
- University of Nebraska
- Lincoln
- USA
| | - Xiaozhe Zhang
- Department of Physics and Astronomy
- University of Nebraska
- Lincoln
- USA
| | - Yuewei Yin
- Department of Physics and Astronomy
- University of Nebraska
- Lincoln
- USA
| | - Xuegang Chen
- Department of Physics and Astronomy
- University of Nebraska
- Lincoln
- USA
| | - Xia Hong
- Department of Physics and Astronomy
- University of Nebraska
- Lincoln
- USA
| | - Xiaoshan Xu
- Department of Physics and Astronomy
- University of Nebraska
- Lincoln
- USA
| | - Peter A. Dowben
- Department of Physics and Astronomy
- University of Nebraska
- Lincoln
- USA
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44
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Senthil Kumar K, Šalitroš I, Boubegtiten-Fezoua Z, Moldovan S, Hellwig P, Ruben M. A spin crossover (SCO) active graphene-iron(ii) complex hybrid material. Dalton Trans 2018; 47:35-40. [DOI: 10.1039/c7dt03623j] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
A graphene-spin crossover (SCO) complex hybrid (Gr-SCO-A), prepared by non-covalently anchoring a pyrene tethered iron(ii)-SCO complex 1 with single/few layer graphene sheets, shows persistent thermal and light induced SCO.
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Affiliation(s)
- Kuppusamy Senthil Kumar
- Institut de Physique et Chimie des Matériaux de Strasbourg (IPCMS)
- CNRS-Université de Strasbourg
- 67034 Strasbourg cedex 2
- France
| | - Ivan Šalitroš
- Institute of Inorganic Chemistry
- Technology and Materials
- Faculty of Chemical and Food Technology
- Slovak University of Technology
- Bratislava
| | - Zahia Boubegtiten-Fezoua
- Laboratoire de Bioélectrochimie et Spectroscopie
- UMR 7140
- Chimie de la Matière Complexe
- Université de Strasbourg CNRS
- 67081 Strasbourg
| | - Simona Moldovan
- Institut de Physique et Chimie des Matériaux de Strasbourg (IPCMS)
- CNRS-Université de Strasbourg
- 67034 Strasbourg cedex 2
- France
- Groupe de Physique des Matériaux (GPM)
| | - Petra Hellwig
- Laboratoire de Bioélectrochimie et Spectroscopie
- UMR 7140
- Chimie de la Matière Complexe
- Université de Strasbourg CNRS
- 67081 Strasbourg
| | - Mario Ruben
- Institut de Physique et Chimie des Matériaux de Strasbourg (IPCMS)
- CNRS-Université de Strasbourg
- 67034 Strasbourg cedex 2
- France
- Institute of Nanotechnology
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45
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Mörtel M, Witt A, Heinemann FW, Bochmann S, Bachmann J, Khusniyarov MM. Synthesis, Characterization, and Properties of Iron(II) Spin-Crossover Molecular Photoswitches Functioning at Room Temperature. Inorg Chem 2017; 56:13174-13186. [DOI: 10.1021/acs.inorgchem.7b01952] [Citation(s) in RCA: 30] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Affiliation(s)
- Max Mörtel
- Department of Chemistry and Pharmacy, Friedrich-Alexander University Erlangen-Nürnberg, Egerlandstrasse 1, 91058 Erlangen, Germany
| | - Alexander Witt
- Department of Chemistry and Pharmacy, Friedrich-Alexander University Erlangen-Nürnberg, Egerlandstrasse 1, 91058 Erlangen, Germany
| | - Frank W. Heinemann
- Department of Chemistry and Pharmacy, Friedrich-Alexander University Erlangen-Nürnberg, Egerlandstrasse 1, 91058 Erlangen, Germany
| | - Sebastian Bochmann
- Department of Chemistry and Pharmacy, Friedrich-Alexander University Erlangen-Nürnberg, Egerlandstrasse 1, 91058 Erlangen, Germany
| | - Julien Bachmann
- Department of Chemistry and Pharmacy, Friedrich-Alexander University Erlangen-Nürnberg, Egerlandstrasse 1, 91058 Erlangen, Germany
| | - Marat M. Khusniyarov
- Department of Chemistry and Pharmacy, Friedrich-Alexander University Erlangen-Nürnberg, Egerlandstrasse 1, 91058 Erlangen, Germany
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Zhang X, Costa PS, Hooper J, Miller DP, N'Diaye AT, Beniwal S, Jiang X, Yin Y, Rosa P, Routaboul L, Gonidec M, Poggini L, Braunstein P, Doudin B, Xu X, Enders A, Zurek E, Dowben PA. Locking and Unlocking the Molecular Spin Crossover Transition. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2017; 29:1702257. [PMID: 28846811 DOI: 10.1002/adma.201702257] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/21/2017] [Revised: 06/19/2017] [Indexed: 06/07/2023]
Abstract
The Fe(II) spin crossover complex [Fe{H2 B(pz)2 }2 (bipy)] (pz = pyrazol-1-yl, bipy = 2,2'-bipyridine) can be locked in a largely low-spin-state configuration over a temperature range that includes temperatures well above the thermal spin crossover temperature of 160 K. This locking of the spin state is achieved for nanometer thin films of this complex in two distinct ways: through substrate interactions with dielectric substrates such as SiO2 and Al2 O3 , or in powder samples by mixing with the strongly dipolar zwitterionic p-benzoquinonemonoimine C6 H2 (-⋯ NH2 )2 (-⋯ O)2 . Remarkably, it is found in both cases that incident X-ray fluences then restore the [Fe{H2 B(pz)2 }2 (bipy)] moiety to an electronic state characteristic of the high spin state at temperatures of 200 K to above room temperature; that is, well above the spin crossover transition temperature for the pristine powder, and well above the temperatures characteristic of light- or X-ray-induced excited-spin-state trapping. Heating slightly above room temperature allows the initial locked state to be restored. These findings, supported by theory, show how the spin crossover transition can be manipulated reversibly around room temperature by appropriate design of the electrostatic and chemical environment.
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Affiliation(s)
- Xin Zhang
- Department of Physics and Astronomy, University of Nebraska, Lincoln, NE, 68588-0299, USA
| | - Paulo S Costa
- Department of Physics and Astronomy, University of Nebraska, Lincoln, NE, 68588-0299, USA
| | - James Hooper
- Department of Theoretical Chemistry, Faculty of Chemistry, Jagiellonian University, Krakow, 30-060, Poland
| | - Daniel P Miller
- Department of Chemistry, University of Buffalo, Buffalo, NY, 14260-3000, USA
| | - Alpha T N'Diaye
- Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA
| | - Sumit Beniwal
- Department of Physics and Astronomy, University of Nebraska, Lincoln, NE, 68588-0299, USA
| | - Xuanyuan Jiang
- Department of Physics and Astronomy, University of Nebraska, Lincoln, NE, 68588-0299, USA
| | - Yuewei Yin
- Department of Physics and Astronomy, University of Nebraska, Lincoln, NE, 68588-0299, USA
| | - Patrick Rosa
- CNRS, Univ. Bordeaux, ICMCB, UPR 9048, F-33600, Pessac, France
| | - Lucie Routaboul
- Université de Strasbourg, CNRS, CHIMIE UMR 7177, Laboratoire de Chimie de Coordination, 4 rue Blaise Pascal, 67081, Strasbourg, France
| | - Mathieu Gonidec
- CNRS, Univ. Bordeaux, ICMCB, UPR 9048, F-33600, Pessac, France
| | - Lorenzo Poggini
- CNRS, Univ. Bordeaux, ICMCB, UPR 9048, F-33600, Pessac, France
| | - Pierre Braunstein
- Université de Strasbourg, CNRS, CHIMIE UMR 7177, Laboratoire de Chimie de Coordination, 4 rue Blaise Pascal, 67081, Strasbourg, France
| | - Bernard Doudin
- University of Strasbourg, CNRS, IPCMS UMR 7504, 23 rue du Loess, 67034, Strasbourg, France
| | - Xiaoshan Xu
- Department of Physics and Astronomy, University of Nebraska, Lincoln, NE, 68588-0299, USA
| | - Axel Enders
- Department of Physics and Astronomy, University of Nebraska, Lincoln, NE, 68588-0299, USA
- Physikalisches Institut, Universität Bayreuth, 95440, Bayreuth, Germany
| | - Eva Zurek
- Department of Chemistry, University of Buffalo, Buffalo, NY, 14260-3000, USA
| | - Peter A Dowben
- Department of Physics and Astronomy, University of Nebraska, Lincoln, NE, 68588-0299, USA
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47
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Senthil Kumar K, Ruben M. Emerging trends in spin crossover (SCO) based functional materials and devices. Coord Chem Rev 2017. [DOI: 10.1016/j.ccr.2017.03.024] [Citation(s) in RCA: 503] [Impact Index Per Article: 71.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
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48
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Spin crossover in iron(II) complexes of 3,4,5-tri-substituted-1,2,4-triazole (Rdpt), 3,5-di-substituted-1,2,4-triazolate (dpt − ), and related ligands. Coord Chem Rev 2017. [DOI: 10.1016/j.ccr.2016.10.006] [Citation(s) in RCA: 69] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
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49
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Kuang G, Zhang Q, Lin T, Pang R, Shi X, Xu H, Lin N. Mechanically-Controlled Reversible Spin Crossover of Single Fe-Porphyrin Molecules. ACS NANO 2017; 11:6295-6300. [PMID: 28498652 DOI: 10.1021/acsnano.7b02567] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/04/2023]
Abstract
Spin-crossover (SCO) molecules are thought to be ideal systems for molecular spintronics when SCO can be precisely controlled at the single-molecule level. This is demonstrated here in the single-molecule junctions of Fe-porphyrin formed in a scanning tunneling microscope. Experimentally, we find that the junctions feature a zero-bias resonance in molecular conductance associated with the Fe spin center. When mechanically stretching or squeezing the junctions by adjusting the tip height, the line shape of the zero-bias resonance varies reversibly. First-principles calculations reveal that widening the junction gap by 2 Å transforms the macrocyclic core hosting the Fe center from a saddle to a planar conformation. This conformational change shortens the Fe-N bonds by 3%, which changes the Fe spin state from S = 2 to S = 1.
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Affiliation(s)
- Guowen Kuang
- Department of Physics, The Hong Kong University of Science and Technology , Hong Kong, China
| | - Qiushi Zhang
- Department of Physics, The Hong Kong University of Science and Technology , Hong Kong, China
| | - Tao Lin
- Department of Physics, The Hong Kong University of Science and Technology , Hong Kong, China
| | - Rui Pang
- Department of Physics, Southern University of Science and Technology of China , Nanshan District, Shenzhen, Guangdong 518055, China
| | - Xingqiang Shi
- Department of Physics, Southern University of Science and Technology of China , Nanshan District, Shenzhen, Guangdong 518055, China
| | - Hu Xu
- Department of Physics, Southern University of Science and Technology of China , Nanshan District, Shenzhen, Guangdong 518055, China
| | - Nian Lin
- Department of Physics, The Hong Kong University of Science and Technology , Hong Kong, China
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50
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Molecular magnetism, quo vadis? A historical perspective from a coordination chemist viewpoint☆. Coord Chem Rev 2017. [DOI: 10.1016/j.ccr.2017.03.004] [Citation(s) in RCA: 240] [Impact Index Per Article: 34.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
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