1
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Trommer C, Kuhlemann E, Engesser TA, Walter M, Thakur S, Kuch W, Tuczek F. Spin crossover in dinuclear iron(II) complexes bridged by bis-bipyridine ligands: dimer effects on electronic structure, spectroscopic properties and spin-state switching. Dalton Trans 2024; 53:9909-9920. [PMID: 38808483 DOI: 10.1039/d4dt00707g] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/30/2024]
Abstract
Inspired by the well-studied mononuclear spin crossover compound [Fe(H2B(pz)2)2(bipy)], the bipyridine-based bisbidentate ligands 1,2-di(2,2'-bipyridin-5-yl)ethyne (ac(bipy)2) and 1,4-di(2,2'-bipyridine-5-yl)-3,5-dimethoxybenzene (Ph(OMe)2(bipy)2) are used to bridge two [Fe(H2B(pz)2)2] units, leading to the charge-neutral dinuclear iron(II) compounds [{Fe(H2B(pz)2)2}2 μ-(ac(bipy)2)] (1) and [{Fe(H2B(pz)2)2}2 μ-(Ph(OMe)2(bipy)2)] (2), respectively. The spin-crossover properties of these molecules are investigated by temperature-dependent PPMS measurements, Mössbauer, vibrational and UV/Vis spectroscopy as well as X-ray absorption spectroscopy. While compound 1 undergoes complete SCO with T1/2 = 125 K, an incomplete spin transition is observed for 2 with an inflection point at 152 K and a remaining high-spin fraction of 40% below 65 K. The spin transitions of the dinuclear compounds are also more gradual than for the parent compound [Fe(H2B(pz)2)2(bipy)]. This is attributed to steric hindrance between the molecules, limiting intermolecular interactions such as π-π-stacking.
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Affiliation(s)
- Clara Trommer
- Institut für Anorganische Chemie, Christian-Albrechts-Universität zu Kiel, Max-Eyth-Straße 2, D-24118 Kiel, Germany.
| | - Eike Kuhlemann
- Institut für Anorganische Chemie, Christian-Albrechts-Universität zu Kiel, Max-Eyth-Straße 2, D-24118 Kiel, Germany.
| | - Tobias A Engesser
- Institut für Anorganische Chemie, Christian-Albrechts-Universität zu Kiel, Max-Eyth-Straße 2, D-24118 Kiel, Germany.
| | - Marcel Walter
- Institut für Experimentalphysik, Freie Universität Berlin, Arnimallee 14, D-14195 Berlin, Germany.
| | - Sangeeta Thakur
- Institut für Experimentalphysik, Freie Universität Berlin, Arnimallee 14, D-14195 Berlin, Germany.
| | - Wolfgang Kuch
- Institut für Experimentalphysik, Freie Universität Berlin, Arnimallee 14, D-14195 Berlin, Germany.
| | - Felix Tuczek
- Institut für Anorganische Chemie, Christian-Albrechts-Universität zu Kiel, Max-Eyth-Straße 2, D-24118 Kiel, Germany.
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2
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Gavara-Edo M, Valverde-Muñoz FJ, Muñoz MC, Elidrissi Moubtassim S, Marques-Moros F, Herrero-Martín J, Znovjyak K, Seredyuk M, Real JA, Coronado E. Design and Processing as Ultrathin Films of a Sublimable Iron(II) Spin Crossover Material Exhibiting Efficient and Fast Light-Induced Spin Transition. CHEMISTRY OF MATERIALS : A PUBLICATION OF THE AMERICAN CHEMICAL SOCIETY 2023; 35:9591-9602. [PMID: 38047182 PMCID: PMC10687866 DOI: 10.1021/acs.chemmater.3c01704] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/07/2023] [Revised: 10/17/2023] [Accepted: 10/18/2023] [Indexed: 12/05/2023]
Abstract
Materials based on spin crossover (SCO) molecules have centered the attention in molecular magnetism for more than 40 years as they provide unique examples of multifunctional and stimuli-responsive materials, which can be then integrated into electronic devices to exploit their molecular bistability. This process often requires the preparation of thermally stable SCO molecules that can sublime and remain intact in contact with surfaces. However, the number of robust sublimable SCO molecules is still very scarce. Here, we report a novel example of this kind. It is based on a neutral iron(II) coordination complex formulated as [Fe(neoim)2], where neoimH is the ionogenic ligand 2-(1H-imidazol-2-yl)-9-methyl-1,10-phenanthroline. In the first part, a comprehensive study, which covers the synthesis and magnetostructural characterization of the [Fe(neoim)2] complex as a bulk microcrystalline material, is reported. Then, in the second part, we investigate the suitability of this material to form thin films through high-vacuum sublimation. Finally, the retainment of all present SCO capabilities in the bulk when the material is processed is thoroughly studied by means of X-ray absorption spectroscopy. In particular, a very efficient and fast light-induced spin transition (LIESST effect) has been observed, even for ultrathin films of 15 nm.
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Affiliation(s)
- Miguel Gavara-Edo
- Instituto
de Ciencia Molecular, Universidad de Valencia, Catedrático José Beltrán
2, Paterna 46980, Spain
| | | | - M. Carmen Muñoz
- Departamento
de Fisica Aplicada, Universitat Politècnica
de València, Camino de Vera s/n, Valencia 46022, Spain
| | - Safaa Elidrissi Moubtassim
- Instituto
de Ciencia Molecular, Universidad de Valencia, Catedrático José Beltrán
2, Paterna 46980, Spain
| | - Francisco Marques-Moros
- Instituto
de Ciencia Molecular, Universidad de Valencia, Catedrático José Beltrán
2, Paterna 46980, Spain
| | | | - Kateryna Znovjyak
- Department
of Chemistry, Taras Shevchenko National
University of Kyiv, 64/13,
Volodymyrska Street, Kyiv 01601, Ukraine
| | - Maksym Seredyuk
- Instituto
de Ciencia Molecular, Universidad de Valencia, Catedrático José Beltrán
2, Paterna 46980, Spain
- Department
of Chemistry, Taras Shevchenko National
University of Kyiv, 64/13,
Volodymyrska Street, Kyiv 01601, Ukraine
| | - José Antonio Real
- Instituto
de Ciencia Molecular, Universidad de Valencia, Catedrático José Beltrán
2, Paterna 46980, Spain
| | - Eugenio Coronado
- Instituto
de Ciencia Molecular, Universidad de Valencia, Catedrático José Beltrán
2, Paterna 46980, Spain
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3
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Sundaresan S, Brooker S. Solution Spin Crossover Versus Speciation Effects: A Cautionary Tale. Inorg Chem 2023. [PMID: 37482662 DOI: 10.1021/acs.inorgchem.3c00186] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 07/25/2023]
Abstract
Two acyclic tetradentate Schiff base ligands, HLX-OH (X = H and Br), were synthesised by 2:1 condensation of either 2-pyridinecarboxaldehyde or 5-bromo-2-pyridinecarboxaldehyde and 1,3-diamino-2-propanol and then used to prepare six mononuclear complexes, [FeII(HLX-OH)(NCE)2], with three different NCE co-ligands (E = BH3, Se, and S). The apparent solution spin crossover switching temperature, T1/2, of these 6 complexes, determined by Evans method NMR studies, is tuned by several factors: (a) substituent X present at the 5 position of the pyridine ring of the ligand, (b) E present in the NCE co-ligand, (c) solvent employed (P'), and (d) potentially also by speciation effects. In CD3CN, for the pair of NCE = NCBH3 complexes, when X = H, the complex is practically LS (extrapolated T1/2 ∼624 K), whereas when X = Br, it is far lower (373 K), which implies a higher field strength when X = H than when it is Br. The same trend, X = H results in a higher apparent T1/2 than X = Br, is seen for the other two pairs of complexes, with E = Se (429 > 351 K, ΔT1/2 = 78 K) or S (361 > 342 K, ΔT1/2 = 19 K). For the family of three X = Br complexes, the change of E from BH3 (373 K) to Se (351 K) to S (342 K) leads to an overall ΔT1/2(apparent) = 31 K, whereas the decreases are far more pronounced in the X = H family (BH3 ∼624 > Se 429 > S 361 K). Changing the solvent used from CD3CN to (CD3)2CO and CD3NO2, for [FeII(HLBr-OH)(NCE)2] with either E = BH3 or S, revealed excellent, and very similar, positive linear correlations (R2 = 0.99) of increasing solvent polarity index P' (from 5 to 7) with increasing apparent T1/2 of the complex (E = BH3 gave T1/2 300 < 373 < 451 K , ΔT1/2 = 151 K; E = S gave T1/2 288 < 342 < 427 K, ΔT1/2 = 147 K). Several other solvent parameters were also correlated with the apparent T1/2 of these complexes (R2 = 0.74-0.96). Excellent linear correlations (R2 = 0.99) are also obtained with the coordination ability (aTM) of the three NCE co-ligands with the apparent T1/2 in both families of compounds, [FeII(HLX-OH)(NCE)2] where X = H or Br. The 15N NMR chemical shifts of the nitrogen atom in the three NCE co-ligands (direct measurement) show modest correlations (R2 = 0.74 for LH-OH family and 0.80 for LBr-OH family) with the apparent T1/2 values of the corresponding complexes.
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Affiliation(s)
- Sriram Sundaresan
- Department of Chemistry and the MacDiarmid Institute for Advanced Materials and Nanotechnology, University of Otago, P.O. Box 56, Dunedin 9054, New Zealand
| | - Sally Brooker
- Department of Chemistry and the MacDiarmid Institute for Advanced Materials and Nanotechnology, University of Otago, P.O. Box 56, Dunedin 9054, New Zealand
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4
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Grunwald J, Torres J, Buchholz A, Näther C, Kämmerer L, Gruber M, Rohlf S, Thakur S, Wende H, Plass W, Kuch W, Tuczek F. Defying the inverse energy gap law: a vacuum-evaporable Fe(ii) low-spin complex with a long-lived LIESST state. Chem Sci 2023; 14:7361-7380. [PMID: 37416721 PMCID: PMC10321519 DOI: 10.1039/d3sc00561e] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2023] [Accepted: 05/25/2023] [Indexed: 07/08/2023] Open
Abstract
The novel vacuum-evaporable complex [Fe(pypypyr)2] (pypypyr = bipyridyl pyrrolide) was synthesised and analysed as bulk material and as a thin film. In both cases, the compound is in its low-spin state up to temperatures of at least 510 K. Thus, it is conventionally considered a pure low-spin compound. According to the inverse energy gap law, the half time of the light-induced excited high-spin state of such compounds at temperatures approaching 0 K is expected to be in the regime of micro- or nanoseconds. In contrast to these expectations, the light-induced high-spin state of the title compound has a half time of several hours. We attribute this behaviour to a large structural difference between the two spin states along with four distinct distortion coordinates associated with the spin transition. This leads to a breakdown of single-mode behaviour and thus drastically decreases the relaxation rate of the metastable high-spin state. These unprecedented properties open up new strategies for the development of compounds showing light-induced excited spin state trapping (LIESST) at high temperatures, potentially around room temperature, which is relevant for applications in molecular spintronics, sensors, displays and the like.
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Affiliation(s)
- Jan Grunwald
- Institut für Anorganische Chemie, Christian-Albrechts-Universität zu Kiel 24098 Kiel Germany +49 431 880 1520 +49 431 880 1410
| | - Jorge Torres
- Institut für Experimentalphysik, Freie Universität Berlin Arnimallee 14 14195 Berlin Germany +49 30 838 452098 +49 30 838 52098
| | - Axel Buchholz
- Institut für Anorganische und Analytische Chemie, Friedrich-Schiller-Universität Jena 07743 Jena Germany
| | - Christian Näther
- Institut für Anorganische Chemie, Christian-Albrechts-Universität zu Kiel 24098 Kiel Germany +49 431 880 1520 +49 431 880 1410
| | - Lea Kämmerer
- Fakultät für Physik and CENIDE, Universität Duisburg-Essen 47048 Duisburg Germany
| | - Manuel Gruber
- Fakultät für Physik and CENIDE, Universität Duisburg-Essen 47048 Duisburg Germany
| | - Sebastian Rohlf
- Institut für Experimentelle und Angewandte Physik, Christian-Albrechts-Universität zu Kiel 24098 Kiel Germany
| | - Sangeeta Thakur
- Institut für Experimentalphysik, Freie Universität Berlin Arnimallee 14 14195 Berlin Germany +49 30 838 452098 +49 30 838 52098
| | - Heiko Wende
- Fakultät für Physik and CENIDE, Universität Duisburg-Essen 47048 Duisburg Germany
| | - Winfried Plass
- Institut für Anorganische und Analytische Chemie, Friedrich-Schiller-Universität Jena 07743 Jena Germany
| | - Wolfgang Kuch
- Institut für Experimentalphysik, Freie Universität Berlin Arnimallee 14 14195 Berlin Germany +49 30 838 452098 +49 30 838 52098
| | - Felix Tuczek
- Institut für Anorganische Chemie, Christian-Albrechts-Universität zu Kiel 24098 Kiel Germany +49 431 880 1520 +49 431 880 1410
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5
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Yazdani S, Phillips J, Ekanayaka TK, Cheng R, Dowben PA. The Influence of the Substrate on the Functionality of Spin Crossover Molecular Materials. Molecules 2023; 28:molecules28093735. [PMID: 37175145 PMCID: PMC10180229 DOI: 10.3390/molecules28093735] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2023] [Revised: 04/18/2023] [Accepted: 04/18/2023] [Indexed: 05/15/2023] Open
Abstract
Spin crossover complexes are a route toward designing molecular devices with a facile readout due to the change in conductance that accompanies the change in spin state. Because substrate effects are important for any molecular device, there are increased efforts to characterize the influence of the substrate on the spin state transition. Several classes of spin crossover molecules deposited on different types of surface, including metallic and non-metallic substrates, are comprehensively reviewed here. While some non-metallic substrates like graphite seem to be promising from experimental measurements, theoretical and experimental studies indicate that 2D semiconductor surfaces will have minimum interaction with spin crossover molecules. Most metallic substrates, such as Au and Cu, tend to suppress changes in spin state and affect the spin state switching process due to the interaction at the molecule-substrate interface that lock spin crossover molecules in a particular spin state or mixed spin state. Of course, the influence of the substrate on a spin crossover thin film depends on the molecular film thickness and perhaps the method used to deposit the molecular film.
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Affiliation(s)
- Saeed Yazdani
- Department of Physics, Indiana University-Purdue University Indianapolis, Indianapolis, IN 46202, USA
| | - Jared Phillips
- Department of Physics, Indiana University-Purdue University Indianapolis, Indianapolis, IN 46202, USA
| | - Thilini K Ekanayaka
- Department of Physics and Astronomy, Jorgensen Hall, University of Nebraska, Lincoln, NE 68588-0299, USA
| | - Ruihua Cheng
- Department of Physics, Indiana University-Purdue University Indianapolis, Indianapolis, IN 46202, USA
| | - Peter A Dowben
- Department of Physics and Astronomy, Jorgensen Hall, University of Nebraska, Lincoln, NE 68588-0299, USA
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6
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Nikovskiy I, Aleshin DY, Novikov VV, Polezhaev AV, Khakina EA, Melnikova EK, Nelyubina YV. Selective Pathway toward Heteroleptic Spin-Crossover Iron(II) Complexes with Pyridine-Based N-Donor Ligands. Inorg Chem 2022; 61:20866-20877. [PMID: 36511893 DOI: 10.1021/acs.inorgchem.2c03270] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
A new synthetic pathway is devised to selectively produce previously elusive heteroleptic iron(II) complexes of terpyridine and N,N'-disubstituted bis(pyrazol-3-yl)pyridines that stabilize the opposite spin states of the metal ion. Such a combination of the ligands in a series of the heteroleptic complexes induces the spin-crossover (SCO) not experienced by the homoleptic complexes of these ligands or shifts it to lower/higher temperatures respective to the SCO-active homoleptic complex. The midpoint temperatures of the resulting SCO span from ca. 200 K to the ambient temperature and beyond the highest temperature accessible by NMR spectroscopy and SQUID magnetometry. The proposed "one-pot" approach is applicable to other N-donor ligands to selectively produce heteroleptic complexes─including those inaccessible by alternative synthetic pathways─with highly tunable SCO behaviors for practical applications in sensing, switching, and multifunctional devices.
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Affiliation(s)
- Igor Nikovskiy
- Nesmeyanov Institute of Organoelement Compounds, Russian Academy of Sciences, Vavilova Str., 28, 119991Moscow, Russia.,Bauman Moscow State Technical University, 2nd Baumanskaya Str., 5, 105005Moscow, Russia
| | - Dmitry Yu Aleshin
- Nesmeyanov Institute of Organoelement Compounds, Russian Academy of Sciences, Vavilova Str., 28, 119991Moscow, Russia
| | - Valentin V Novikov
- Bauman Moscow State Technical University, 2nd Baumanskaya Str., 5, 105005Moscow, Russia.,Moscow Institute of Physics and Technology, Institutskiy per., 9, 141700Dolgoprudny, Russia
| | - Alexander V Polezhaev
- Bauman Moscow State Technical University, 2nd Baumanskaya Str., 5, 105005Moscow, Russia
| | - Ekaterina A Khakina
- Nesmeyanov Institute of Organoelement Compounds, Russian Academy of Sciences, Vavilova Str., 28, 119991Moscow, Russia.,HSE University, Miasnitskaya Str., 20, 101000Moscow, Russia
| | - Elizaveta K Melnikova
- Nesmeyanov Institute of Organoelement Compounds, Russian Academy of Sciences, Vavilova Str., 28, 119991Moscow, Russia
| | - Yulia V Nelyubina
- Nesmeyanov Institute of Organoelement Compounds, Russian Academy of Sciences, Vavilova Str., 28, 119991Moscow, Russia.,Bauman Moscow State Technical University, 2nd Baumanskaya Str., 5, 105005Moscow, Russia
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7
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Mirzanejad A, Varganov SA. The role of the intermediate triplet state in iron-catalyzed multi-state C-H activation. Phys Chem Chem Phys 2022; 24:20721-20727. [PMID: 36018581 DOI: 10.1039/d2cp02733j] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Efficient activation and functionalization of the C-H bond under mild conditions are of a great interest in chemical synthesis. We investigate the previously proposed spin-accelerated activation of the C(sp2)-H bond by a Fe(II)-based catalyst to clarify the role of the intermediate triplet state in the reaction mechanism. High-level electronic structure calculations on a small model of a catalytic system utilizing the coupled cluster with the single, double, and perturbative triple excitations [CCSD(T)] are used to select the density functional for the full-size model. Our analysis indicates that the previously proposed two-state quintet-singlet reaction pathway is unlikely to be efficient due to a very weak spin-orbit coupling between these two spin states. We propose a more favorable multi-state quintet-triplet-singlet reaction pathway and discuss the importance of the intermediate triplet state. This triplet state facilitates a spin-accelerated reaction mechanism by strongly coupling to both quintet and singlet states. Our calculations show that the C-H bond activation through the proposed quintet-triplet-singlet reaction pathway is more thermodynamically favorable than the single-state quintet and two-state singlet-quintet mechanisms.
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Affiliation(s)
- Amir Mirzanejad
- Department of Chemistry, University of Nevada, Reno, 1664 N. Virginia Street, Reno, NV 89557-0216, USA.
| | - Sergey A Varganov
- Department of Chemistry, University of Nevada, Reno, 1664 N. Virginia Street, Reno, NV 89557-0216, USA.
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8
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Hao G, Dale AS, N'Diaye AT, Chopdekar RV, Koch RJ, Jiang X, Mellinger C, Zhang J, Cheng R, Xu X, Dowben PA. Intermolecular interaction and cooperativity in an Fe(II) spin crossover molecular thin film system. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2022; 34:295201. [PMID: 35508146 DOI: 10.1088/1361-648x/ac6cbc] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/22/2022] [Accepted: 05/04/2022] [Indexed: 06/14/2023]
Abstract
Compact domain features have been observed in spin crossover [Fe{H2B(pz)2}2(bipy)] molecular thin film systems via soft x-ray absorption spectroscopy and photoemission electron microscopy. The domains are in a mixed spin state that on average corresponds to roughly 2/3 the high spin occupation of the pure high spin state. Monte Carlo simulations support the presence of intermolecular interactions that can be described in terms of an Ising model in which interactions beyond nearest-neighbors cannot be neglected. This suggests the presence of short-range order to permit interactions between molecules beyond nearest neighbor that contribute to the formation of largely high spin state domains structure. The formation of a spin state domain structure appears to be the result of extensive cooperative effects.
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Affiliation(s)
- Guanhua Hao
- Department of Physics and Astronomy, Jorgensen Hall, University of Nebraska, Lincoln, NE 68588, United States of America
- Advanced Light Source, Lawrence Berkeley National Lab, One Cyclotron Rd, Berkeley, CA 94720, United States of America
| | - Ashley S Dale
- Department of Physics, Indiana University-Purdue University Indianapolis, Indianapolis, Indiana 46202, United States of America
| | - Alpha T N'Diaye
- Advanced Light Source, Lawrence Berkeley National Lab, One Cyclotron Rd, Berkeley, CA 94720, United States of America
| | - Rajesh V Chopdekar
- Advanced Light Source, Lawrence Berkeley National Lab, One Cyclotron Rd, Berkeley, CA 94720, United States of America
| | - Roland J Koch
- Advanced Light Source, Lawrence Berkeley National Lab, One Cyclotron Rd, Berkeley, CA 94720, United States of America
| | - Xuanyuan Jiang
- Department of Physics and Astronomy, Jorgensen Hall, University of Nebraska, Lincoln, NE 68588, United States of America
| | - Corbyn Mellinger
- Department of Physics and Astronomy, Jorgensen Hall, University of Nebraska, Lincoln, NE 68588, United States of America
| | - Jian Zhang
- The Molecular Foundry, Lawrence Berkeley National Laboratory, One Cyclotron Road, Berkeley, CA 94720, United States of America
| | - Ruihua Cheng
- Department of Physics, Indiana University-Purdue University Indianapolis, Indianapolis, Indiana 46202, United States of America
| | - Xiaoshan Xu
- Department of Physics and Astronomy, Jorgensen Hall, University of Nebraska, Lincoln, NE 68588, United States of America
| | - Peter A Dowben
- Department of Physics and Astronomy, Jorgensen Hall, University of Nebraska, Lincoln, NE 68588, United States of America
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9
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Johannsen S, Ossinger S, Grunwald J, Herman A, Wende H, Tuczek F, Gruber M, Berndt R. Spin Crossover in a Cobalt Complex on Ag(111). Angew Chem Int Ed Engl 2022; 61:e202115892. [PMID: 35032345 PMCID: PMC9303790 DOI: 10.1002/anie.202115892] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2021] [Indexed: 12/05/2022]
Abstract
The Co‐based complex [Co(H2B(pz)(pypz))2] (py=pyridine, pz=pyrazole) deposited on Ag(111) was investigated with scanning tunneling microscopy at ≈5 K. Due to a bis(tridentate) coordination sphere the molecules aggregate mainly into tetramers. Individual complexes in these tetramers undergo reversible transitions between two states with characteristic image contrasts when current is passed through them or one of their neighbors. Two molecules exhibit this bistability while the other two molecules are stable. The transition rates vary linearly with the tunneling current and exhibit an intriguing dependence on the bias voltage and its polarity. We interpret the states as being due to S=1/2 and 3/2 spin states of the Co2+ complex. The image contrast and the orders‐of‐magnitude variations of the switching yields can be tentatively understood from the calculated orbital structures of the two spin states, thus providing first insights into the mechanism of electron‐induced excited spin‐state trapping (ELIESST).
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Affiliation(s)
- Sven Johannsen
- Institut für Experimentelle und Angewandte Physik, Christian-Albrechts-Universität, 24098, Kiel, Germany
| | - Sascha Ossinger
- Institut für Anorganische Chemie, Christian-Albrechts-Universität, 24098, Kiel, Germany.,Department of Chemistry, University of Basel, St. Johanns-Ring 19, 4056, Basel, Switzerland
| | - Jan Grunwald
- Institut für Anorganische Chemie, Christian-Albrechts-Universität, 24098, Kiel, Germany
| | - Alexander Herman
- Faculty of Physics and CENIDE, University of Duisburg-Essen, 47057, Duisburg, Germany
| | - Heiko Wende
- Faculty of Physics and CENIDE, University of Duisburg-Essen, 47057, Duisburg, Germany
| | - Felix Tuczek
- Institut für Anorganische Chemie, Christian-Albrechts-Universität, 24098, Kiel, Germany
| | - Manuel Gruber
- Institut für Experimentelle und Angewandte Physik, Christian-Albrechts-Universität, 24098, Kiel, Germany.,Faculty of Physics and CENIDE, University of Duisburg-Essen, 47057, Duisburg, Germany
| | - Richard Berndt
- Institut für Experimentelle und Angewandte Physik, Christian-Albrechts-Universität, 24098, Kiel, Germany
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10
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Johannsen S, Ossinger S, Grunwald J, Herman A, Wende H, Tuczek F, Gruber M, Berndt R. Spin Crossover in a Cobalt Complex on Ag(111). Angew Chem Int Ed Engl 2022. [DOI: 10.1002/ange.202115892] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Affiliation(s)
- Sven Johannsen
- Institut für Experimentelle und Angewandte Physik Christian-Albrechts-Universität 24098 Kiel Germany
| | - Sascha Ossinger
- Institut für Anorganische Chemie Christian-Albrechts-Universität 24098 Kiel Germany
- Department of Chemistry University of Basel St. Johanns-Ring 19 4056 Basel Switzerland
| | - Jan Grunwald
- Institut für Anorganische Chemie Christian-Albrechts-Universität 24098 Kiel Germany
| | - Alexander Herman
- Faculty of Physics and CENIDE University of Duisburg-Essen 47057 Duisburg Germany
| | - Heiko Wende
- Faculty of Physics and CENIDE University of Duisburg-Essen 47057 Duisburg Germany
| | - Felix Tuczek
- Institut für Anorganische Chemie Christian-Albrechts-Universität 24098 Kiel Germany
| | - Manuel Gruber
- Institut für Experimentelle und Angewandte Physik Christian-Albrechts-Universität 24098 Kiel Germany
- Faculty of Physics and CENIDE University of Duisburg-Essen 47057 Duisburg Germany
| | - Richard Berndt
- Institut für Experimentelle und Angewandte Physik Christian-Albrechts-Universität 24098 Kiel Germany
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11
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Investigation of a Tetrathiafulvalene-Based Fe2+ Thermal Spin Crossover Assembled on Gold Surface. MAGNETOCHEMISTRY 2022. [DOI: 10.3390/magnetochemistry8020014] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
A thick film and a monolayer of tetrathiafulvalene-based Fe2+ spin-crossover complex have been deposited by solution on a Au (111) substrate, attempting both self-assembling monolayer protocol and a simpler drop-casting procedure. The thermally induced spin transition has been investigated using X-ray photoelectron spectroscopy (XPS) and X-ray absorption spectroscopy (XAS). Temperature-dependent investigations demonstrated the retention of the switching behavior between the two spin states in thick molecular films obtained by drop-casting, while in the monolayer sample, the loss of the spin-crossover properties appears as a possible consequence of the strong interaction between the sulfur atoms of the ligand and the gold substrate.
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12
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Krebs C, Jess I, Näther C. Comparison of the crystal structures of the low- and high-temperature forms of bis-[4-(di-methyl-amino)-pyridine]-dithio-cyanato-cobalt(II). Acta Crystallogr E Crystallogr Commun 2021; 77:1120-1125. [PMID: 34868648 PMCID: PMC8587972 DOI: 10.1107/s2056989021010422] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2021] [Accepted: 10/07/2021] [Indexed: 11/11/2022]
Abstract
Single crystals of the high-temperature form I of [Co(NCS)2(DMAP)2] (DMAP = 4-di-methyl-amino-pyridine, C7H10N2) were obtained accidentally by the reaction of Co(NCS)2 with DMAP at slightly elevated temperatures under kinetic control. This modification crystallizes in the monoclinic space group P21/m and is isotypic with the corresponding Zn compound. The asymmetric unit consists of one crystallographically independent Co cation and two crystallographically independent thio-cyanate anions that are located on a crystallographic mirror plane and one DMAP ligand (general position). In its crystal structure the discrete complexes are linked by C-H⋯S hydrogen bonds into a three-dimensional network. For comparison, the crystal structure of the known low-temperature form II, which is already thermodynamically stable at room temperature, was redetermined at the same temperature. In this polymorph the complexes are connected by C-H⋯S and C-H⋯N hydrogen bonds into a three-dimensional network. At 100 K the density of the high-temperature form I (ρ = 1.462 g cm-3) is higher than that of the low-temperature form II (ρ = 1.457 g cm-3), which is in contrast to the values determined by XRPD at room temperature. Therefore, these two forms represent an exception to the Kitaigorodskii density rule, for which extensive inter-molecular hydrogen bonding in form II might be responsible.
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Affiliation(s)
- Christoph Krebs
- Institute of Inorganic Chemistry, University of Kiel, Max-Eyth.-Str. 2, 24118 Kiel, Germany
| | - Inke Jess
- Institute of Inorganic Chemistry, University of Kiel, Max-Eyth.-Str. 2, 24118 Kiel, Germany
| | - Christian Näther
- Institute of Inorganic Chemistry, University of Kiel, Max-Eyth.-Str. 2, 24118 Kiel, Germany
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13
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Johannsen S, Ossinger S, Markussen T, Tuczek F, Gruber M, Berndt R. Electron-Induced Spin-Crossover in Self-Assembled Tetramers. ACS NANO 2021; 15:11770-11778. [PMID: 34133115 DOI: 10.1021/acsnano.1c02698] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
The spin crossover compound Fe(H2B(pyrazole)(pyridylpyrazole))2 was investigated in detail on Ag(111) with scanning tunneling microscopy (STM). A large fraction of the deposited molecules condenses into gridlike tetramers. Two molecules of each tetramer may be converted between two states by current injection. We attribute this effect to a spin transition. This interpretation is supported by control experiments on the analogous, magnetically passive Zn compound that forms virtually identical tetramers but exhibits no switching. The switching yields were studied for various electron energies, and the resulting values exceed those reported from other SCO systems by 2 orders of magnitude. The other two molecules of a tetramer were immutable. However, they may be used as contacts for current injection that leads to conversion of one of their neighbors. This "remote" switching is fairly efficient with yields reduced by only one to two orders of magnitude compared to direct excitation of a switchable molecule. We present a model of the tetramer structure that reproduces key observations from the experiments. In particular, sterical blocking prevents spin crossover of two molecules of a tetramer. Density functional theory calculations show that the model indeed represents a minimum energy structure. They also reproduce STM images and corroborate a remote-switching mechanism that is based on electron transfer between molecules.
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Affiliation(s)
- Sven Johannsen
- Institut für Experimentelle und Angewandte Physik, Christian-Albrechts-Universität, 24098 Kiel, Germany
| | - Sascha Ossinger
- Institut für Anorganische Chemie, Christian-Albrechts-Universität, 24098 Kiel, Germany
| | - Troels Markussen
- Synopsys Denmark, Fruebjergvej 3, Postbox 4, DK-2100 Copenhagen, Denmark
| | - Felix Tuczek
- Institut für Anorganische Chemie, Christian-Albrechts-Universität, 24098 Kiel, Germany
| | - Manuel Gruber
- Institut für Experimentelle und Angewandte Physik, Christian-Albrechts-Universität, 24098 Kiel, Germany
- Faculty of Physics, University of Duisburg-Essen, 47057 Duisburg, Germany
| | - Richard Berndt
- Institut für Experimentelle und Angewandte Physik, Christian-Albrechts-Universität, 24098 Kiel, Germany
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14
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Guo Y, Rotaru A, Müller-Bunz H, Morgan GG, Zhang S, Xue S, Garcia Y. Auxiliary alkyl chain modulated spin crossover behaviour of [Fe(H 2Bpz 2) 2(C n-bipy)] complexes. Dalton Trans 2021; 50:12835-12842. [PMID: 34309614 DOI: 10.1039/d1dt01787j] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Three new alkyl chain substituted complexes [Fe(H2Bpz2)2(Cn-bipy)] (pz = pyrazolyl, Cn-bipy = bipyridine alkyl chain diester, n = 3 (3), 4 (4) and 5 (5)) show versatile spin state switching behaviour with different "tail" lengths as revealed by structural and magnetic analyses. The most striking phenomenon is observed for 5 which undergoes an abrupt spin transition accompanied by thermal hysteresis of ca. 10 K, which is attributed to crystal packing effects derived from the competition between ππ and C-HO interactions. Interestingly, each of the complexes exhibits similar gradual and complete spin crossover in methanol solution with a transition temperature around 249 K, as deduced from temperature-dependent UV-vis spectroscopy. This highlights the differences between the solid state (ligand field; crystal packing) and solution (ligand field; solvation) effects on spin crossover. This work demonstrates that the length of the complex's alkyl chain substituents on the complex can have a large impact on the transition temperature and profile of solid state spin crossover, offering a potential path to the fabrication of soft matter spin crossover materials.
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Affiliation(s)
- Yunnan Guo
- Department of Chemistry, Key Laboratory of Surface & Interface Science of Polymer Materials of Zhejiang Province, Zhejiang Sci-Tech University, Hangzhou 310018, China. and Institute of Condensed Matter and Nanosciences, Molecular Chemistry, Materials and Catalysis (IMCN/MOST), Université catholique de Louvain, Place L. Pasteur 1, Louvain-la-Neuve 1348, Belgium.
| | - Aurelian Rotaru
- Department of Electrical Engineering and Computer Science & MANSiD Research Center, "Stefan cel Mare" University, University Street, 13, Suceava 720229, Romania
| | - Helge Müller-Bunz
- School of Chemistry, University College Dublin, Belfield, Dublin 4, Ireland
| | - Grace G Morgan
- School of Chemistry, University College Dublin, Belfield, Dublin 4, Ireland
| | - Shishen Zhang
- Department of Chemistry, Key Laboratory of Surface & Interface Science of Polymer Materials of Zhejiang Province, Zhejiang Sci-Tech University, Hangzhou 310018, China.
| | - Shufang Xue
- Department of Chemistry, Key Laboratory of Surface & Interface Science of Polymer Materials of Zhejiang Province, Zhejiang Sci-Tech University, Hangzhou 310018, China. and Institute of Condensed Matter and Nanosciences, Molecular Chemistry, Materials and Catalysis (IMCN/MOST), Université catholique de Louvain, Place L. Pasteur 1, Louvain-la-Neuve 1348, Belgium.
| | - Yann Garcia
- Institute of Condensed Matter and Nanosciences, Molecular Chemistry, Materials and Catalysis (IMCN/MOST), Université catholique de Louvain, Place L. Pasteur 1, Louvain-la-Neuve 1348, Belgium.
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15
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Heras Ojea MJ, Van Raden JM, Louie S, Collins R, Pividori D, Cirera J, Meyer K, Jasti R, Layfield RA. Spin‐Crossover Properties of an Iron(II) Coordination Nanohoop. Angew Chem Int Ed Engl 2021. [DOI: 10.1002/ange.202013374] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Affiliation(s)
| | - Jeff M. Van Raden
- Department of Chemistry and Biochemistry and Materials Science Institute University of Oregon Eugene OR 97403 USA
| | - Shayan Louie
- Department of Chemistry and Biochemistry and Materials Science Institute University of Oregon Eugene OR 97403 USA
| | - Richard Collins
- Department of Chemistry University of Sussex Brighton BN1 9QJ UK
| | - Daniel Pividori
- Department of Chemistry and Pharmacy Inorganic Chemistry Friedrich-Alexander University Erlangen-Nürnberg (FAU) Egerlandstrasse 1 91058 Erlangen Germany
| | - 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
| | - Karsten Meyer
- Department of Chemistry and Pharmacy Inorganic Chemistry Friedrich-Alexander University Erlangen-Nürnberg (FAU) Egerlandstrasse 1 91058 Erlangen Germany
| | - Ramesh Jasti
- Department of Chemistry and Biochemistry and Materials Science Institute University of Oregon Eugene OR 97403 USA
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16
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Heras Ojea MJ, Van Raden JM, Louie S, Collins R, Pividori D, Cirera J, Meyer K, Jasti R, Layfield RA. Spin-Crossover Properties of an Iron(II) Coordination Nanohoop. Angew Chem Int Ed Engl 2020; 60:3515-3518. [PMID: 33112017 DOI: 10.1002/anie.202013374] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2020] [Indexed: 12/20/2022]
Abstract
Addition of the bipyridyl-embedded cycloparaphenylene nanohoop bipy[9]CPP to [Fe{H2 B(pyz)2 }] (pyz=pyrazolyl) produces the distorted octahedral complex [Fe(bipy[9]CPP){H2 B(pyz)2 }2 ] (1). The molecular structure of 1 shows that the nanohoop ligand contains a non-planar bipy unit. Magnetic susceptibility measurements indicate spin-crossover (SCO) behaviour with a T1/2 of 130 K, lower than that of 160 K observed with the related compound [Fe(bipy){H2 B(pyz)2 }2 ] (2), which contains a conventional bipy ligand. A computational study of 1 and 2 reveals that the curvature of the nanohoop leads to the different SCO properties, suggesting that the SCO behaviour of iron(II) can be tuned by varying the size and diameter of the nanohoop.
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Affiliation(s)
| | - Jeff M Van Raden
- Department of Chemistry and Biochemistry and Materials Science Institute, University of Oregon, Eugene, OR, 97403, USA
| | - Shayan Louie
- Department of Chemistry and Biochemistry and Materials Science Institute, University of Oregon, Eugene, OR, 97403, USA
| | - Richard Collins
- Department of Chemistry, University of Sussex, Brighton, BN1 9QJ, UK
| | - Daniel Pividori
- Department of Chemistry and Pharmacy, Inorganic Chemistry, Friedrich-Alexander University Erlangen-Nürnberg (FAU), Egerlandstrasse 1, 91058, Erlangen, Germany
| | - 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
| | - Karsten Meyer
- Department of Chemistry and Pharmacy, Inorganic Chemistry, Friedrich-Alexander University Erlangen-Nürnberg (FAU), Egerlandstrasse 1, 91058, Erlangen, Germany
| | - Ramesh Jasti
- Department of Chemistry and Biochemistry and Materials Science Institute, University of Oregon, Eugene, OR, 97403, USA
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17
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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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18
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Ossinger S, Näther C, Tuczek F. Crystal structure of bis-{(3,5-di-methyl-pyrazol-1-yl)di-hydro-[3-(pyridin-2-yl)pyrazol-1-yl]-borato}iron(II). Acta Crystallogr E Crystallogr Commun 2020; 76:1266-1270. [PMID: 32844011 PMCID: PMC7405558 DOI: 10.1107/s2056989020009214] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2020] [Accepted: 07/06/2020] [Indexed: 11/10/2022]
Abstract
The structure determination of [Fe(C13H15BN5)2] was undertaken as part of a project on the modification of the recently published spin-crossover (SCO) complex [Fe{H2B(pz)(pypz)}2] (pz = pyrazole, pypz = pyridyl-pyrazole). To this end, a new ligand was synthesized in which two additional methyl groups are present. Its reaction with iron tri-fluoro-methane-sulfonate led to a pure sample of the title compound, as proven by X-ray powder diffraction. The asymmetric unit consists of one complex mol-ecule in a general position. The FeII atom is coordinated by two tridentate N-binding {H2B(3,5-(CH3)2-pz)(pypz)}- ligands. The Fe-N bond lengths range between 2.1222 (13) and 2.3255 (15) Å, compatible with FeII in the high-spin state, which was also confirmed by magnetic measurements. Other than a very weak C-H⋯N non-classical hydrogen bond linking individual mol-ecules into rows extending parallel to [010], there are no remarkable inter-molecular inter-actions.
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Affiliation(s)
- Sascha Ossinger
- Institut für Anorganische Chemie, Christian-Albrechts-Universität Kiel, Max-Eyth-Str. 2, D-24118 Kiel, Germany
| | - Christian Näther
- Institut für Anorganische Chemie, Christian-Albrechts-Universität Kiel, Max-Eyth-Str. 2, D-24118 Kiel, Germany
| | - Felix Tuczek
- Institut für Anorganische Chemie, Christian-Albrechts-Universität Kiel, Max-Eyth-Str. 2, D-24118 Kiel, Germany
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19
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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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20
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Cini A, Poggini L, Chumakov AI, Rüffer R, Spina G, Wattiaux A, Duttine M, Gonidec M, Fittipaldi M, Rosa P, Mannini M. Synchrotron-based Mössbauer spectroscopy characterization of sublimated spin crossover molecules. Phys Chem Chem Phys 2020; 22:6626-6637. [PMID: 32159166 DOI: 10.1039/c9cp04464g] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
The spin crossover (SCO) efficiency of [57Fe(bpz)2(phen)] (where bpz = bis(pyrazol-1-yl)borohydride and phen = 9,10-phenantroline) molecules deposited on gold substrates was investigated by means of synchrotron Mössbauer spectroscopy. The spin transition was driven thermally, or light induced via the LIESST (light induced excited spin-state trapping) effect. Both sets of measurements show that, once deposited on a gold substrate, the efficiency of the SCO mechanism is modified with respect to molecules in the bulk phase. A correlation in the distribution of hyperfine parameters in the sublimated films, not evidenced so far in the bulk phase, is reported. This translates into geometrical distortions of the first coordination sphere of the iron atom that seem to correlate with the decreased spin conversion. The work reported clearly shows the potentiality of synchrotron Mössbauer spectroscopy for the characterization of nanostructured Fe-based SCO systems, thus resulting as a key tool in view of their applications in innovative nanoscale devices.
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Affiliation(s)
- Alberto Cini
- Department of Physics and Astronomy, University of Florence and INSTM Research Unit of Florence, via Sansone 1, I-50019 Sesto Fiorentino (FI), Italy.
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