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Zakrzewski J, Liberka M, Wang J, Chorazy S, Ohkoshi SI. Optical Phenomena in Molecule-Based Magnetic Materials. Chem Rev 2024; 124:5930-6050. [PMID: 38687182 PMCID: PMC11082909 DOI: 10.1021/acs.chemrev.3c00840] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/02/2024]
Abstract
Since the last century, we have witnessed the development of molecular magnetism which deals with magnetic materials based on molecular species, i.e., organic radicals and metal complexes. Among them, the broadest attention was devoted to molecule-based ferro-/ferrimagnets, spin transition materials, including those exploring electron transfer, molecular nanomagnets, such as single-molecule magnets (SMMs), molecular qubits, and stimuli-responsive magnetic materials. Their physical properties open the application horizons in sensors, data storage, spintronics, and quantum computation. It was found that various optical phenomena, such as thermochromism, photoswitching of magnetic and optical characteristics, luminescence, nonlinear optical and chiroptical effects, as well as optical responsivity to external stimuli, can be implemented into molecule-based magnetic materials. Moreover, the fruitful interactions of these optical effects with magnetism in molecule-based materials can provide new physical cross-effects and multifunctionality, enriching the applications in optical, electronic, and magnetic devices. This Review aims to show the scope of optical phenomena generated in molecule-based magnetic materials, including the recent advances in such areas as high-temperature photomagnetism, optical thermometry utilizing SMMs, optical addressability of molecular qubits, magneto-chiral dichroism, and opto-magneto-electric multifunctionality. These findings are discussed in the context of the types of optical phenomena accessible for various classes of molecule-based magnetic materials.
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Affiliation(s)
- Jakub
J. Zakrzewski
- Faculty
of Chemistry, Jagiellonian University, Gronostajowa 2, 30-387 Krakow, Poland
- Doctoral
School of Exact and Natural Sciences, Jagiellonian
University, Lojasiewicza
11, 30-348 Krakow, Poland
| | - Michal Liberka
- Faculty
of Chemistry, Jagiellonian University, Gronostajowa 2, 30-387 Krakow, Poland
- Doctoral
School of Exact and Natural Sciences, Jagiellonian
University, Lojasiewicza
11, 30-348 Krakow, Poland
| | - Junhao Wang
- Department
of Materials Science, Faculty of Pure and Applied Science, University of Tsukuba, 1-1-1 Tonnodai, Tsukuba, Ibaraki 305-8573, Japan
| | - Szymon Chorazy
- Faculty
of Chemistry, Jagiellonian University, Gronostajowa 2, 30-387 Krakow, Poland
| | - Shin-ichi Ohkoshi
- Department
of Chemistry, School of Science, The University
of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan
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2
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Brook DJR, DaRos J, Ponnekanti A, Agrestini S, Pellegrin E. Spectroscopic and thermodynamic characterization of a cobalt-verdazyl valence tautomeric system. influence of crystal structure, solvent and counterion. Dalton Trans 2024; 53:7536-7545. [PMID: 38597992 DOI: 10.1039/d4dt00465e] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/11/2024]
Abstract
Crystallization of the verdazyl-based valence tautomeric ion [Co(dipyvd)2]2+ (where dipyvd is the radical ligand 1-isopropyl-3,5-di(2'-pyridyl)-6-oxoverdazyl) with a variety of different counterions results in materials that show varying degrees of valence tautomeric (VT) transition in the solid state. The X-ray structure of the SbF6 salt at 150 K reveals a localized structure for the S = 1/2 tautomer, with a Co3+ cation and distinct anionic and radical ligands. Comparison with the structure of the same material at 300 K reveals large structural changes in the ligand as a result of the valence tautomeric equilibrium. Data for the S = 3/2 form is less conclusive; X-ray spectroscopy on the PF6 salt suggests a degree of low spin Co2+ character for the S = 3/2 tautomer at very low temperature though this is inconsistent with EPR data at similar temperatures and structural information at 150 K. Magnetic measurements on the [BArF4]- and triflate salts in organic solvents show that the VT equilibrium is dependent on solvent and ion pairing effects.
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Affiliation(s)
- David J R Brook
- Department of Chemistry, San Jose State University, San Jose, CA 95192, USA.
| | - Jeffrey DaRos
- Department of Chemistry, San Jose State University, San Jose, CA 95192, USA.
| | - Aamani Ponnekanti
- Department of Chemistry, San Jose State University, San Jose, CA 95192, USA.
| | - Stefano Agrestini
- ALBA Synchrotron Light Source, E-08290 Cerdanyola del Vallès, Barcelona, Spain
| | - Eric Pellegrin
- ALBA Synchrotron Light Source, E-08290 Cerdanyola del Vallès, Barcelona, Spain
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3
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Fleming C, Vu S, Brook DJR, Agrestini S, Pellegrin E, DaRos J. Metal-ligand interactions in a redox active ligand system. Electrochemistry and spectroscopy of [M(dipyvd) 2] n+ (M=Zn, Ni, n=0, 1, 2). Front Chem 2023; 11:1295289. [PMID: 38033468 PMCID: PMC10684738 DOI: 10.3389/fchem.2023.1295289] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2023] [Accepted: 10/27/2023] [Indexed: 12/02/2023] Open
Abstract
Reaction of nickel and zinc triflates with the tridentate leucoverdazyl 1-isopropyl-3,5-di (2'-pyridyl)-6-oxo-2H-tetrazine (dipyvdH) and triethylamine resulted in the neutral coordination compounds M(dipyvd)2 (M = Ni,Zn). In acetonitrile, both compounds undergo two one electron oxidation processes, Zn (dipyvd)2 at -0.28 V and -0.12 V and Ni(dipyvd)2 at -0.32 V and -0.15 V vs ferrocene/ferricenium. Oxidations are ligand based resulting in an intermediate mixed valence species and a cationic bis(verdazyl) compound respectively. Oxidation of the ligand changes a localized, antiaromatic, non-planar 8π electron anion to a planar, delocalized 7π electron radical. The change in ligand structure results in an increase in the octahedral ligand field splitting from 10,500 cm-1 to ∼13,000 cm-1, suggesting an increase in the pi acceptor character of the ligand. In the mixed valence species, spectroscopic data suggests minimal interaction between ligands mediated by the metal center; i.e., these are class I-II systems in the Robin-Day classification.
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Affiliation(s)
- Connor Fleming
- Department of Chemistry, San Jose State University, San Jose, CA, United States
| | - Son Vu
- Department of Chemistry, San Jose State University, San Jose, CA, United States
| | - David J. R. Brook
- Department of Chemistry, San Jose State University, San Jose, CA, United States
| | - Stefano Agrestini
- ALBA Synchrotron Light Source, E-08290 Cerdanyola del Vallès, Barcelona, Spain
| | - Eric Pellegrin
- ALBA Synchrotron Light Source, E-08290 Cerdanyola del Vallès, Barcelona, Spain
| | - Jeffrey DaRos
- Department of Chemistry, San Jose State University, San Jose, CA, United States
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4
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Moledo Vicente Guedes A, Sodré de Abreu L, Maldonado IAV, Fernandes WS, Cardozo TM, A Allão Cassaro R, Scarpellini M, Poneti G. Valence tautomerism in a cobalt-dioxolene complex containing an imidazolic ancillary ligand. RSC Adv 2023; 13:20050-20057. [PMID: 37409047 PMCID: PMC10318486 DOI: 10.1039/d3ra03235c] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2023] [Accepted: 06/22/2023] [Indexed: 07/07/2023] Open
Abstract
This work reports the synthesis, structural, spectroscopic and magnetic investigation of two complexes, [Co(bmimapy)(3,5-DTBCat)]PF6·H2O (1) and [Co(bmimapy)(TCCat)]PF6·H2O (2), where bmimapy is an imidazolic tetradentate ancillary ligand and 3,5-DTBCat and TCCat are the 3,5-di-tert-butyl-catecholate and tetrachlorocatecholate anions, respectively. Their structures have been elucidated using single crystal X-ray diffraction, showing a pseudo-octahedral cobalt ion bound to a chelating dioxolene ligand and the ancillary bmimapy ligand in a folded conformation. Magnetometry displayed an entropy-driven, incomplete, Valence Tautomeric (VT) process for 1 in the 300-380 K temperature range, while 2 displayed a temperature independent, diamagnetic low-spin cobalt(iii)-catecholate charge distribution. This behaviour was interpreted on the basis of the cyclic voltammetric analysis, allowing the estimation of the free energy difference associated with the VT interconversion of +8 and +96 kJ mol-1 for 1 and 2, respectively. A DFT analysis of this free energy difference highlighted the ability of the methyl-imidazole pendant arm of bmimapy favouring the onset of the VT phenomenon. This work introduces the imidazolic bmimapy ligand to the scientific community working in the field of valence tautomerism, increasing the library of ancillary ligands to prepare temperature switchable molecular magnetic materials.
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Affiliation(s)
| | - Leandro Sodré de Abreu
- Instituto de Química, Universidade Federal do Rio de Janeiro Rio de Janeiro RJ 21941-909 Brazil
| | | | - William Silva Fernandes
- Instituto de Química, Universidade Federal do Rio de Janeiro Rio de Janeiro RJ 21941-909 Brazil
| | - Thiago Messias Cardozo
- Instituto de Química, Universidade Federal do Rio de Janeiro Rio de Janeiro RJ 21941-909 Brazil
| | - Rafael A Allão Cassaro
- Instituto de Química, Universidade Federal do Rio de Janeiro Rio de Janeiro RJ 21941-909 Brazil
| | - Marciela Scarpellini
- Instituto de Química, Universidade Federal do Rio de Janeiro Rio de Janeiro RJ 21941-909 Brazil
| | - Giordano Poneti
- Instituto de Química, Universidade Federal do Rio de Janeiro Rio de Janeiro RJ 21941-909 Brazil
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Roseiro P, Yalouz S, Brook DJR, Ben Amor N, Robert V. Modifications of Tanabe-Sugano d6 Diagram Induced by Radical Ligand Field: Ab Initio Inspection of a Fe(II)-Verdazyl Molecular Complex. Inorg Chem 2023; 62:5737-5743. [PMID: 36971364 DOI: 10.1021/acs.inorgchem.3c00275] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/29/2023]
Abstract
Quantum entanglement between the spin states of a metal center and radical ligands is suggested in an iron(II) [Fe(dipyvd)2]2+ compound (dipyvd = 1-isopropyl-3,5-dipyridil-6-oxoverdazyl). Wave function ab initio (Difference Dedicated Configuration Interaction, DDCI) inspections were carried out to stress the versatility of local spin states. We named this phenomenon excited state spinmerism, in reference to our previous work (see Roseiro et al., ChemPhysChem 2022, e202200478) where we introduced the concept of spinmerism as an extension of mesomerism to spin degrees of freedom. The construction of localized molecular orbitals allows for a reading of the wave functions and projections onto the local spin states. The low-energy spectrum is well-depicted by a Heisenberg picture. A 60 cm-1 ferromagnetic interaction is calculated between the radical ligands with the Stotal = 0 and 1 states largely dominated by a local low-spin SFe = 0. In contrast, the higher-lying Stotal = 2 states are superpositions of the local SFe = 1 (17%, 62%) and SFe = 2 (72%, 21%) spin states. Such mixing extends the traditional picture of a high-field d6 Tanabe-Sugano diagram. Even in the absence of spin-orbit coupling, the avoided crossing between different local spin states is triggered by the field generated by radical ligands. This puzzling scenario emerges from versatile local spin states in compounds which extend the traditional views in molecular magnetism.
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6
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Ziółkowska A, Witwicki M. Understanding the Exchange Interaction between Paramagnetic Metal Ions and Radical Ligands: DFT and Ab Initio Study on Semiquinonato Cu(II) Complexes. Int J Mol Sci 2023; 24:ijms24044001. [PMID: 36835412 PMCID: PMC9959031 DOI: 10.3390/ijms24044001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2022] [Revised: 02/10/2023] [Accepted: 02/13/2023] [Indexed: 02/18/2023] Open
Abstract
The exchange coupling, represented by the J parameter, is of tremendous importance in understanding the reactivity and magnetic behavior of open-shell molecular systems. In the past, it was the subject of theoretical investigations, but these studies are mostly limited to the interaction between metallic centers. The exchange coupling between paramagnetic metal ions and radical ligands has hitherto received scant attention in theoretical studies, and thus the understanding of the factors governing this interaction is lacking. In this paper, we use DFT, CASSCF, CASSCF/NEVPT2, and DDCI3 methods to provide insight into exchange interaction in semiquinonato copper(II) complexes. Our primary objective is to identify structural features that affect this magnetic interaction. We demonstrate that the magnetic character of Cu(II)-semiquinone complexes are mainly determined by the relative position of the semiquinone ligand to the Cu(II) ion. The results can support the experimental interpretation of magnetic data for similar systems and can be used for the in-silico design of magnetic complexes with radical ligands.
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Affiliation(s)
- Aleksandra Ziółkowska
- Faculty of Chemistry, Wroclaw University of Science and Technology, Wybrzeże Wyspiańskiego 27, 50-370 Wroclaw, Poland
| | - Maciej Witwicki
- Faculty of Chemistry, Wroclaw University, F. Joliot-Curie 14, 50-283 Wroclaw, Poland
- Correspondence:
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7
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Teslenko FE, Fershtat LL. Unlocking Kuhn Verdazyls: New Synthetic Approach and Useful Mechanistic Insights. Int J Mol Sci 2023; 24:ijms24032693. [PMID: 36769015 PMCID: PMC9916651 DOI: 10.3390/ijms24032693] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2022] [Revised: 01/20/2023] [Accepted: 01/20/2023] [Indexed: 02/04/2023] Open
Abstract
An optimized synthetic protocol toward the assembly of Kuhn verdazyls based on an azo coupling of arenediazonium salts with readily available hydrazones followed by the base-mediated cyclization of in situ formed formazans with formalin was developed. The scope and limitations of the presented method were revealed. Some new mechanistic insights on the formation of Kuhn verdazyls were also conducted. It was found that in contradiction with previously assumed hypotheses, the synthesis of verdazyls was accomplished via an intermediate formation of verdazylium cations which were in situ reduced to leucoverdazyls. The latter underwent deprotonation under basic conditions to generate corresponding anions which coproportionate with verdazylium cations to furnish the formation of Kuhn verdazyls. The spectroscopic and electrochemical behavior of the synthesized verdazyls was also studied. Overall, our results may serve as a reliable basis for further investigation in the chemistry and applications of verdazyls.
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8
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Roseiro P, Petit L, Robert V, Yalouz S. Emergence of Spinmerism for Molecular Spin-Qubits Generation. Chemphyschem 2023; 24:e202200478. [PMID: 36161748 DOI: 10.1002/cphc.202200478] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2022] [Revised: 09/20/2022] [Indexed: 01/20/2023]
Abstract
Molecular platforms are regarded as promising candidates in the generation of units of information for quantum computing. Herein, a strategy combining spin-crossover metal ions and radical ligands is proposed from a model Hamiltonian first restricted to exchange interactions. Unusual spin states structures emerge from the linkage of a singlet/triplet commutable metal centre with two doublet-radical ligands. The ground state nature is modulated by charge transfers and can exhibit a mixture of triplet and singlet local metal spin states. Besides, the superposition reaches a maximum for 2 K M = K 1 + K 2 ${2{K}_{M}={K}_{1}+{K}_{2}}$ , suggesting a necessary competition between the intramolecular K M ${{K}_{M}}$ and inter-metal-ligand K 1 ${{K}_{1}}$ and K 2 ${{K}_{2}}$ direct exchange interactions. The results promote spinmerism, an original manifestation of quantum entanglement between the spin states of a metal centre and radical ligands. The study provides insights into spin-coupled compounds and inspiration for the development of molecular spin-qubits.
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Affiliation(s)
- Pablo Roseiro
- Laboratoire de Chimie Quantique, Institut de Chimie, CNRS/, Université de Strasbourg, 4 rue Blaise Pascal, 67000, Strasbourg, France
| | - Louis Petit
- Laboratoire de Chimie Quantique, Institut de Chimie, CNRS/, Université de Strasbourg, 4 rue Blaise Pascal, 67000, Strasbourg, France
| | - Vincent Robert
- Laboratoire de Chimie Quantique, Institut de Chimie, CNRS/, Université de Strasbourg, 4 rue Blaise Pascal, 67000, Strasbourg, France
| | - Saad Yalouz
- Laboratoire de Chimie Quantique, Institut de Chimie, CNRS/, Université de Strasbourg, 4 rue Blaise Pascal, 67000, Strasbourg, France
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9
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Hay MA, Janetzki JT, Kumar VJ, Gable RW, Clérac R, Starikova AA, Low PJ, Boskovic C. Modulation of Charge Distribution in Cobalt-α-Diimine Complexes toward Valence Tautomerism. Inorg Chem 2022; 61:17609-17622. [DOI: 10.1021/acs.inorgchem.2c02659] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Moya A. Hay
- School of Chemistry, University of Melbourne, Parkville, Victoria 3010, Australia
| | - Jett T. Janetzki
- School of Chemistry, University of Melbourne, Parkville, Victoria 3010, Australia
| | - Varshini J. Kumar
- School of Molecular Sciences, University of Western Australia, 35 Stirling Highway, Crawley, Western Australia 6009, Australia
| | - Robert W. Gable
- School of Chemistry, University of Melbourne, Parkville, Victoria 3010, Australia
| | - Rodolphe Clérac
- University of Bordeaux, CNRS, CRPP, UMR 5031, F-33600 Pessac, France
| | - Alyona A. Starikova
- Institute of Physical and Organic Chemistry, Southern Federal University, 344090 Rostov-on-Don, Russian Federation
| | - Paul J. Low
- School of Molecular Sciences, University of Western Australia, 35 Stirling Highway, Crawley, Western Australia 6009, Australia
| | - Colette Boskovic
- School of Chemistry, University of Melbourne, Parkville, Victoria 3010, Australia
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10
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Lipunova GN, Fedorchenko TG, Chupakhin ON. Verdazyls in Coordination Chemistry. RUSS J COORD CHEM+ 2022. [DOI: 10.1134/s1070328422070065] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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11
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Roseiro P, Ben Amor N, Robert V. Combining Open-Shell Verdazyl Environment and Co(II) Spin-Crossover: Spinmerism in Cobalt Oxoverdazyl Compound. Chemphyschem 2022; 23:e202100801. [PMID: 35212147 DOI: 10.1002/cphc.202100801] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2021] [Revised: 02/11/2022] [Indexed: 11/07/2022]
Abstract
The spin states of a Co(II) oxoverdazyl compound are investigated by means of wavefunction-based calculations. Within a ca. 233 K energy window, the ground state and excited states display a structure-sensitive admixture of low-spin SM = 1/2 in a dominant high-spin SM = 3/2 Co(II) ion as read from localized molecular orbitals. This puzzling spins zoology that results from the coupling between open-shell radical ligands and a spin-crossover metal ion gives rise to this unusual scenario which extends the views in molecular magnetism. In agreement with experimental observation, the low-energy spectroscopy is very sensitive to deformations of the coordination sphere, and a growing admixture of Co(II) low-spin is evidenced from the calculations. In analogy with mesomerism that accounts for charge delocalization, entanglement combines different local spin states to generate a given total spin multiplicity, a spinmerism phenomenon.
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Affiliation(s)
- Pablo Roseiro
- UMR7177: Institut de Chimie de Strasbourg, Laboratoire de Chimie Quantique, 4 rue Blaise Pascal, 67000, Strasbourg, FRANCE
| | - Nadia Ben Amor
- UMR5626: Laboratoire de Chimie et Physique Quantique, Laboratoire de Chimie et Physique Quantiques, 118 route de Narbonne, 31062, Toulouse, FRANCE
| | - Vincent Robert
- Laboratoire de Chimie Quantique, Universit� de Strasbourg, Department of Chemistry, 4 rue Blaise Pascal, 67000, Strasbourg, FRANCE
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12
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Witwicki M, Lewińska A, Ozarowski A. o-Semiquinone radical anion isolated as an amorphous porous solid. Phys Chem Chem Phys 2021; 23:17408-17419. [PMID: 34351330 DOI: 10.1039/d1cp01596f] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The use of metal cations is a commonly applied strategy to create S > 1/2 stable molecular systems containing semiquinone radicals. Persistent mono-semiquinonato complexes of diamagnetic metal ions (S = 1/2) have been hitherto less common and mostly limited to the complexes of heavy metal ions. In this work, a mono-semiquinonato complex of aluminum, derived from 1,2-dihydroxybenzene, is obtained using a surprisingly short and uncomplicated procedure. The isolated product is an amorphous and porous solid that exhibits very good stability under ambient conditions. To characterise its molecular and electronic structure, 9.7, 34 and 406 GHz EPR spectroscopy was used in concert with computational techniques (DFT and DLPNO-CCSD). It was revealed that the radical complex is composed of two chemically equivalent aluminum cations and two catechol-like ligands with the unpaired electron uniformly distributed between the two organic molecules. The good stability and porous structure make this complex applicable in heterogeneous aerobic reactions.
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Affiliation(s)
- Maciej Witwicki
- Faculty of Chemistry, Wroclaw University, Joliot-Curie 14, 50-383 Wroclaw, Poland.
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13
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Lohmeyer L, Kaifer E, Enders M, Himmel H. Switching from Metal- to Ligand-Based Oxidation in Cobalt Complexes with Redox-Active Bisguanidine Ligands. Chemistry 2021; 27:11852-11867. [PMID: 34101917 PMCID: PMC8457109 DOI: 10.1002/chem.202101364] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2021] [Indexed: 11/19/2022]
Abstract
The control of the redox reactivity, magnetic and optical properties of the different redox states of complexes with redox‐active ligands permits their rational use in catalysis and materials science. The redox‐chemistry of octahedrally coordinated high‐spin CoII complexes (three unpaired electrons) with one redox‐active bisguanidine ligand and two acetylacetonato (acac) co‐ligands is completely changed by replacing the acac by hexafluoro‐acetylacetonato (hfacac) co‐ligands. The first one‐electron oxidation is metal‐centered in the case of the complexes with acac co‐ligands, giving diamagnetic CoIII complexes. By contrast, in the case of the less Lewis‐basic hfacac co‐ligands, the first one‐electron oxidation becomes ligand‐centered, leading to high‐spin CoII complexes with a radical monocationic guanidine ligand unit (four unpaired electrons). Ferromagnetic coupling between the spins on the metal and the organic radical in solution is evidenced by temperature‐dependent paramagnetic NMR studies, allowing to estimate the isotropic exchange coupling constant in solution. Second one‐electron oxidation leads to high‐spin CoII complexes with dicationic guanidine ligand units (three unpaired electrons) in the presence of hfacac co‐ligands, but to low‐spin CoIII complexes with radical monocationic, peralkylated guanidine ligand (one unpaired electron) in the presence of acac co‐ligands. The analysis of the electronic structures is complemented by quantum‐chemical calculations on the spin density distributions and relative energies of the possible redox isomers.
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Affiliation(s)
- Lukas Lohmeyer
- Inorganic ChemistryRuprecht-Karls University of HeidelbergIm Neuenheimer Feld 27069120HeidelbergGermany
| | - Elisabeth Kaifer
- Inorganic ChemistryRuprecht-Karls University of HeidelbergIm Neuenheimer Feld 27069120HeidelbergGermany
| | - Markus Enders
- Inorganic ChemistryRuprecht-Karls University of HeidelbergIm Neuenheimer Feld 27069120HeidelbergGermany
| | - Hans‐Jörg Himmel
- Inorganic ChemistryRuprecht-Karls University of HeidelbergIm Neuenheimer Feld 27069120HeidelbergGermany
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14
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Bonanno NM, Watts Z, Mauws C, Patrick BO, Wiebe CR, Shibano Y, Sugisaki K, Matsuoka H, Shiomi D, Sato K, Takui T, Lemaire MT. Valence tautomerism in a [2 × 2] Co 4 grid complex containing a ditopic arylazo ligand. Chem Commun (Camb) 2021; 57:6213-6216. [PMID: 34059865 DOI: 10.1039/d1cc01991k] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
We describe the structural and magnetic properties of a tetranuclear [2 × 2] Co4 grid complex containing a ditopic arylazo ligand. At low temperatures and in solution the complex is comprised of Co3+ and singly reduced trianion-radical ligands. In the solid state we demonstrate the presence of valence tautomerization via variable temperature magnetic susceptibility experiments and powder-pattern EPR spectroscopy. Valence tautomerism in polynuclear complexes is very rare and to our knowledge is unprecedented in [2 × 2] grid complexes.
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Affiliation(s)
- Nico M Bonanno
- Department of Chemistry, Brock University, St. Catharines, ON L2S 3A1, Canada.
| | - Zackery Watts
- Department of Chemistry, Brock University, St. Catharines, ON L2S 3A1, Canada.
| | - Cole Mauws
- Department of Chemistry, University of Manitoba, Winnipeg, MB R3T 2N2, Canada
| | - Brian O Patrick
- Department of Chemistry, University of British of Columbia, Vancouver, BC V6T 1Z1, Canada
| | - Christopher R Wiebe
- Department of Chemistry, University of Manitoba, Winnipeg, MB R3T 2N2, Canada and Department of Chemistry, University of Winnipeg, Winnipeg, MB R3B 2E9, Canada
| | - Yuki Shibano
- Department of Chemistry and Molecular Materials Science, Graduate School of Science, Osaka City University, Osaka 558 8585, Japan
| | - Kenji Sugisaki
- Department of Chemistry and Molecular Materials Science, Graduate School of Science, Osaka City University, Osaka 558 8585, Japan
| | - Hideto Matsuoka
- Department of Chemistry and Molecular Materials Science, Graduate School of Science, Osaka City University, Osaka 558 8585, Japan
| | - Daisuke Shiomi
- Department of Chemistry and Molecular Materials Science, Graduate School of Science, Osaka City University, Osaka 558 8585, Japan
| | - Kazunobu Sato
- Department of Chemistry and Molecular Materials Science, Graduate School of Science, Osaka City University, Osaka 558 8585, Japan
| | - Takeji Takui
- Department of Chemistry and Molecular Materials Science, Graduate School of Science, Osaka City University, Osaka 558 8585, Japan
| | - Martin T Lemaire
- Department of Chemistry, Brock University, St. Catharines, ON L2S 3A1, Canada.
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15
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Casper LA, Linseis M, Demeshko S, Azarkh M, Drescher M, Winter RF. Tailoring Valence Tautomerism by Using Redox Potentials: Studies on Ferrocene-Based Triarylmethylium Dyes with Electron-Poor Fluorenylium and Thioxanthylium Acceptors. Chemistry 2021; 27:10854-10868. [PMID: 33901313 PMCID: PMC8361958 DOI: 10.1002/chem.202101032] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2021] [Indexed: 01/31/2023]
Abstract
Three new electrochromic ferrocenyl triarylmethylium dyes with fluorenylium (1 a+ , 1 b+ ) or thioxanthylium (1 c+ ) residues were selected in order to keep the intrinsic differences of redox potentials for ferrocene oxidation and triarylmethylium reduction small and to trigger valence tautomerism (VT). UV/Vis/NIR and quantitative EPR spectroscopy identified paramagnetic diradical isomers 1 a..+ -1 c..+ alongside diamagnetic forms 1 a+ -1 c+ , which renders these complexes magnetochemical switches. The diradical forms 1 a..+ -1 c..+ as well as the one-electron-reduced triarylmethyl forms of the complexes were found to dimerize in solution. For radical 1 a. , dimerization occurs on the timescale of cyclic voltammetry; this allowed us to determine the kinetics and equilibrium constant for this process by digital simulation. Mößbauer spectroscopy indicated that 1 a+ and 1 b+ retain VT even in the solid state. UV/Vis/NIR spectro-electrochemistry revealed the poly-electrochromic behaviour of these complexes by establishing the distinctly different electronic absorption profiles of the corresponding oxidized and reduced forms.
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Affiliation(s)
- Larissa A Casper
- Fachbereich Chemie, Universität Konstanz, Universitätsstraße 10, 78457, Konstanz, Germany
| | - Michael Linseis
- Fachbereich Chemie, Universität Konstanz, Universitätsstraße 10, 78457, Konstanz, Germany
| | - Serhiy Demeshko
- Institut für Anorganische Chemie, Georg-August-Universität Göttingen, Tammannstraße 4, 37077, Göttingen, Germany
| | - Mykhailo Azarkh
- Fachbereich Chemie, Universität Konstanz, Universitätsstraße 10, 78457, Konstanz, Germany
| | - Malte Drescher
- Fachbereich Chemie, Universität Konstanz, Universitätsstraße 10, 78457, Konstanz, Germany
| | - Rainer F Winter
- Fachbereich Chemie, Universität Konstanz, Universitätsstraße 10, 78457, Konstanz, Germany
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Lecourt C, Izumi Y, Maryunina K, Inoue K, Bélanger-Desmarais N, Reber C, Desroches C, Luneau D. Hypersensitive pressure-dependence of the conversion temperature of hysteretic valence tautomeric manganese-nitronyl nitroxide radical 2D-frameworks. Chem Commun (Camb) 2021; 57:2376-2379. [PMID: 33537684 DOI: 10.1039/d0cc08144b] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
Valence tautomeric manganese(ii)-radical lamellar compounds {[Mn2(NITIm)3]X}n with NITIm a nitronyl nitroxide radical and X = ClO4- (1) or BF4- (2) show a pressure-induced increase of their conversion temperature by approximately 40 K at a mild external pressure of 0.1 GPa, shifting the transition from near room temperature to hot temperature regions.
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Affiliation(s)
- Constance Lecourt
- Univ Lyon, Université Claude Bernard Lyon 1, CNRS, Laboratoire des Multimatériaux et Interfaces, F-69622 Villeurbanne, France.
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17
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Nadurata VL, Boskovic C. Switching metal complexes via intramolecular electron transfer: connections with solvatochromism. Inorg Chem Front 2021. [DOI: 10.1039/d0qi01490g] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
Solvent-induced color-changing phenomena exhibited by some metal complexes can illuminate key aspects of their switchable behavior.
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Lecourt C, Izumi Y, Khrouz L, Toche F, Chiriac R, Bélanger-Desmarais N, Reber C, Fabelo O, Inoue K, Desroches C, Luneau D. Thermally-induced hysteretic valence tautomeric conversions in the solid state via two-step labile electron transfers in manganese-nitronyl nitroxide 2D-frameworks. Dalton Trans 2020; 49:15646-15662. [PMID: 33156311 DOI: 10.1039/d0dt03243c] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Near room temperature hysteretic thermo-induced valence tautomerism was discovered in a layered 2D-coordination polymer of manganese(ii) with nitronyl nitroxide radicals separated by ClO4- anions (1). This opens a novel approach towards switchable materials with hysteresis and under ambient conditions with prospects for applications and for investigating solid-state intramolecular electron transfers. Herein, two new compounds with similar layered structures where the anions (X) are BF4- (2) or PF6- (3) are presented. Their magnetic behaviors also reveal hysteretic thermo-induced valence tautomeric conversions but in two steps and evidencing a strong effect of the anion. This occurs near room temperature (278-220 K) for 2 and higher for 3 (380-330 K). Their single crystal structures at different temperatures show that this involves two successive thermally-triggered electron transfers with switching between three redox tautomers formulated as {[MnII2-yMnIIIy(NITIm)3-y(NITRed)y]X}n, where y is temperature dependent. Upon cooling from the high-temperature redox-tautomer (y = 0) to the intermediate one (y = 1), half of the manganese(ii) centers are oxidized to manganese(iii) and 1/3 of the nitronyl nitroxide radicals (NITIm-) are reduced to the aminoxyl form (NITRed2-). On further cooling, the second half of the manganese(ii) centers are oxidized and another 1/3 of the radicals are reduced to reach the low-temperature redox-tautomer (y = 2). Upon reheating, reverse electron transfers occur. This is complementarily supported by X-ray powder measurements, differential scanning calorimetry, and electron paramagnetic resonance and Raman spectroscopies. These multi-stable compounds in which manganese ions exchange reversibly their electron with the nitronyl nitroxide radical are outstanding rare examples of two-step valence tautomerism in the solid state promoted by the polymeric structure.
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Affiliation(s)
- Constance Lecourt
- Laboratoire des Multimatériaux et Interfaces, UMR CNRS 5615, Univ Lyon, Université Claude Bernard Lyon 1, F-69622 Villeurbanne, France.
| | - Yuuta Izumi
- Department of Chemistry, Graduate School of Science and Chirality Research Center (CResCent), Hiroshima University, 1-3-1, Kagamiyama, Higashi Hiroshima, Hiroshima, 739-8526, Japan
| | - Lhoussain Khrouz
- Univ Lyon, ENS de Lyon, CNRS UMR 5182, Université Claude Bernard Lyon 1, Laboratoire de Chimie, F69342, Lyon, France
| | - François Toche
- Laboratoire des Multimatériaux et Interfaces, UMR CNRS 5615, Univ Lyon, Université Claude Bernard Lyon 1, F-69622 Villeurbanne, France.
| | - Rodica Chiriac
- Laboratoire des Multimatériaux et Interfaces, UMR CNRS 5615, Univ Lyon, Université Claude Bernard Lyon 1, F-69622 Villeurbanne, France.
| | | | - Christian Reber
- Département de chimie, Université de Montréal, Montréal, Québec H3C 3J7, Canada
| | - Oscar Fabelo
- Institut Laue-Langevin, 71 avenue des Martyrs, 38042 Grenoble Cedex 9, France
| | - Katsuya Inoue
- Department of Chemistry, Graduate School of Science and Chirality Research Center (CResCent), Hiroshima University, 1-3-1, Kagamiyama, Higashi Hiroshima, Hiroshima, 739-8526, Japan
| | - Cédric Desroches
- Laboratoire des Multimatériaux et Interfaces, UMR CNRS 5615, Univ Lyon, Université Claude Bernard Lyon 1, F-69622 Villeurbanne, France.
| | - Dominique Luneau
- Laboratoire des Multimatériaux et Interfaces, UMR CNRS 5615, Univ Lyon, Université Claude Bernard Lyon 1, F-69622 Villeurbanne, France.
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