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Sorace L, Raju N, O'Shaughnessy J, Kachel S, Jansz K, Yang N, Lim RP. Assessment of inspiration and technical quality in anteroposterior thoracic radiographs using machine learning. Radiography (Lond) 2024; 30:107-115. [PMID: 37918335 DOI: 10.1016/j.radi.2023.10.014] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2023] [Revised: 10/16/2023] [Accepted: 10/17/2023] [Indexed: 11/04/2023]
Abstract
INTRODUCTION Chest radiographs are the most performed radiographic procedure, but suboptimal technical factors can impact clinical interpretation. A deep learning model was developed to assess technical and inspiratory adequacy of anteroposterior chest radiographs. METHODS Adult anteroposterior chest radiographs (n = 2375) were assessed for technical adequacy, and if otherwise technically adequate, for adequacy of inspiration. Images were labelled by an experienced radiologist with one of three ground truth labels: inadequate technique (n = 605, 25.5 %), adequate inspiration (n = 900, 37.9 %), and inadequate inspiration (n = 870, 36.6 %). A convolutional neural network was then iteratively trained to predict these labels and evaluated using recall, precision, F1 and micro-F1, and Gradient-weighted Class Activation Mapping analysis on a hold-out test set. Impact of kyphosis on model accuracy was assessed. RESULTS The model performed best for radiographs with adequate technique, and worst for images with inadequate technique. Recall was highest (89 %) for radiographs with both adequate technique and inspiration, with recall of 81 % for images with adequate technique and inadequate inspiration, and 60 % for images with inadequate technique, although precision was highest (85 %) for this category. Per-class F1 was 80 %, 81 % and 70 % for adequate inspiration, inadequate inspiration, and inadequate technique respectively. Weighted F1 and Micro F1 scores were 78 %. Presence or absence of kyphosis had no significant impact on model accuracy in images with adequate technique. CONCLUSION This study explores the promising performance of a machine learning algorithm for assessment of inspiratory adequacy and overall technical adequacy for anteroposterior chest radiograph acquisition. IMPLICATIONS FOR PRACTICE With further refinement, machine learning can contribute to education and quality improvement in radiology departments.
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Affiliation(s)
- L Sorace
- Department of Radiology, Austin Hospital, Heidelberg, Australia.
| | - N Raju
- Department of Radiology, Austin Hospital, Heidelberg, Australia
| | - J O'Shaughnessy
- Department of Radiology, Austin Hospital, Heidelberg, Australia
| | - S Kachel
- Department of Radiology, Austin Hospital, Heidelberg, Australia; The University of Melbourne, Parkville, Australia; Columbia University, New York, NY, USA
| | - K Jansz
- Department of Radiology, Austin Hospital, Heidelberg, Australia
| | - N Yang
- Department of Radiology, Austin Hospital, Heidelberg, Australia; The University of Melbourne, Parkville, Australia
| | - R P Lim
- Department of Radiology, Austin Hospital, Heidelberg, Australia; The University of Melbourne, Parkville, Australia
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Bonizzoni C, Ghirri A, Atzori M, Sorace L, Sessoli R, Affronte M. Coherent coupling between Vanadyl Phthalocyanine spin ensemble and microwave photons: towards integration of molecular spin qubits into quantum circuits. Sci Rep 2017; 7:13096. [PMID: 29026118 PMCID: PMC5638858 DOI: 10.1038/s41598-017-13271-w] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2017] [Accepted: 09/21/2017] [Indexed: 11/13/2022] Open
Abstract
Electron spins are ideal two-level systems that may couple with microwave photons so that, under specific conditions, coherent spin-photon states can be realized. This represents a fundamental step for the transfer and the manipulation of quantum information. Along with spin impurities in solids, molecular spins in concentrated phases have recently shown coherent dynamics under microwave stimuli. Here we show that it is possible to obtain high cooperativity regime between a molecular Vanadyl Phthalocyanine (VOPc) spin ensemble and a high quality factor superconducting YBa2Cu3O7 (YBCO) coplanar resonator at 0.5 K. This demonstrates that molecular spin centers can be successfully integrated in hybrid quantum devices.
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Affiliation(s)
- C Bonizzoni
- Dipartimento di Scienze Fisiche, Informatiche e Matematiche, Università di Modena e Reggio Emilia, via G. Campi 213/A, 41125, Modena, Italy. .,Istituto Nanoscienze S3, CNR via G. Campi 213/A, 41125, Modena, Italy.
| | - A Ghirri
- Istituto Nanoscienze S3, CNR via G. Campi 213/A, 41125, Modena, Italy
| | - M Atzori
- Dipartimento di Chimica "Ugo Schiff" & INSTM RU, Università degli Studi di Firenze, Via della Lastruccia 3, 50019, Sesto Fiorentino (Firenze), Italy
| | - L Sorace
- Dipartimento di Chimica "Ugo Schiff" & INSTM RU, Università degli Studi di Firenze, Via della Lastruccia 3, 50019, Sesto Fiorentino (Firenze), Italy
| | - R Sessoli
- Dipartimento di Chimica "Ugo Schiff" & INSTM RU, Università degli Studi di Firenze, Via della Lastruccia 3, 50019, Sesto Fiorentino (Firenze), Italy
| | - M Affronte
- Dipartimento di Scienze Fisiche, Informatiche e Matematiche, Università di Modena e Reggio Emilia, via G. Campi 213/A, 41125, Modena, Italy.,Istituto Nanoscienze S3, CNR via G. Campi 213/A, 41125, Modena, Italy
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Amjad A, Figuerola A, Sorace L. Tm(iii) complexes undergoing slow relaxation of magnetization: exchange coupling and aging effects. Dalton Trans 2017; 46:3848-3856. [PMID: 28322380 DOI: 10.1039/c6dt04691f] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The present study focuses on the dynamic magnetic behaviour of exchange coupled 3d-4f complexes containing the scarcely investigated non-Kramers Tm3+ center, the 3d metal ions being either the low-spin Fe3+ (1) or the diamagnetic Co3+ (2) ion. Both complexes display field-induced slow relaxation of magnetization. The field and temperature dependences of the relaxation rate provided indication of relevant contributions from quantum tunnelling, direct, Orbach and Raman processes, with only minor effects from exchange coupling interactions. Furthermore, the aged sample of 2 exhibited an additional relaxation process, possibly due to structural modifications accompanied by solvent loss, highlighting the importance of a careful consideration of this factor when analysing the magnetization dynamics in solvated systems.
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Affiliation(s)
- A Amjad
- INSTM Research unit & Dipartimento di Chimica "U. Schiff", Università degli Studi di Firenze, Via della Lastruccia 3, 50019 Sesto Fiorentino, Fl, Italy.
| | - A Figuerola
- Departament de Química Inorgànica i Orgànica, Secció de Química Inorgànica, i Institut de Nanociència i Nanotecnologia (IN2UB), Universitat de Barcelona, Martí i Franquès 1-11, E-08028 Barcelona, Spain
| | - L Sorace
- INSTM Research unit & Dipartimento di Chimica "U. Schiff", Università degli Studi di Firenze, Via della Lastruccia 3, 50019 Sesto Fiorentino, Fl, Italy.
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Tesi L, Lunghi A, Atzori M, Lucaccini E, Sorace L, Totti F, Sessoli R. Giant spin–phonon bottleneck effects in evaporable vanadyl-based molecules with long spin coherence. Dalton Trans 2016; 45:16635-16643. [DOI: 10.1039/c6dt02559e] [Citation(s) in RCA: 64] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The smaller the ligand the slower the low temperature magnetization dynamics of the crystals of vanadyl complexes.
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Affiliation(s)
- L. Tesi
- Dipartimento di Chimica “U. Schiff” and INSTM UdR Firenze
- Università degli Studi di Firenze
- I50019 Sesto Fiorentino
- Italy
| | - A. Lunghi
- Dipartimento di Chimica “U. Schiff” and INSTM UdR Firenze
- Università degli Studi di Firenze
- I50019 Sesto Fiorentino
- Italy
- School of Physics
| | - M. Atzori
- Dipartimento di Chimica “U. Schiff” and INSTM UdR Firenze
- Università degli Studi di Firenze
- I50019 Sesto Fiorentino
- Italy
| | - E. Lucaccini
- Dipartimento di Chimica “U. Schiff” and INSTM UdR Firenze
- Università degli Studi di Firenze
- I50019 Sesto Fiorentino
- Italy
| | - L. Sorace
- Dipartimento di Chimica “U. Schiff” and INSTM UdR Firenze
- Università degli Studi di Firenze
- I50019 Sesto Fiorentino
- Italy
| | - F. Totti
- Dipartimento di Chimica “U. Schiff” and INSTM UdR Firenze
- Università degli Studi di Firenze
- I50019 Sesto Fiorentino
- Italy
| | - R. Sessoli
- Dipartimento di Chimica “U. Schiff” and INSTM UdR Firenze
- Università degli Studi di Firenze
- I50019 Sesto Fiorentino
- Italy
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Bonizzoni C, Ghirri A, Bader K, van Slageren J, Perfetti M, Sorace L, Lan Y, Fuhr O, Ruben M, Affronte M. Coupling molecular spin centers to microwave planar resonators: towards integration of molecular qubits in quantum circuits. Dalton Trans 2016; 45:16596-16603. [DOI: 10.1039/c6dt01953f] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
Strong coupling meets coordination chemistry: hints in the design of molecular qubits in hybrid quantum circuits.
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Affiliation(s)
- C. Bonizzoni
- Dipartimento FIM
- Università di Modena e Reggio Emilia
- 411125 Modena
- Italy
- Istituto Nanoscienze - CNR
| | - A. Ghirri
- Istituto Nanoscienze - CNR
- 411125 Modena
- Italy
| | - K. Bader
- Institut für Physikalische Chemie
- Universität Stuttgart
- 70569 Stuttgart
- Germany
| | - J. van Slageren
- Institut für Physikalische Chemie
- Universität Stuttgart
- 70569 Stuttgart
- Germany
| | - M. Perfetti
- Dipartimento di Chimica “U. Schiff” and UdR INSTM
- Università di Firenze
- 50019 Sesto Fiorentino(FI)
- Italy
| | - L. Sorace
- Dipartimento di Chimica “U. Schiff” and UdR INSTM
- Università di Firenze
- 50019 Sesto Fiorentino(FI)
- Italy
| | - Y. Lan
- Institute of Nanotechnology
- Karlsruhe Institute of Technology (KIT)
- D-76344 Eggenstein-Leopoldshafen
- Germany
| | - O. Fuhr
- Institute of Nanotechnology
- Karlsruhe Institute of Technology (KIT)
- D-76344 Eggenstein-Leopoldshafen
- Germany
| | - M. Ruben
- Institute of Nanotechnology
- Karlsruhe Institute of Technology (KIT)
- D-76344 Eggenstein-Leopoldshafen
- Germany
- Institut de Physique et Chimie des Matériaux de Strasbourg
| | - M. Affronte
- Dipartimento FIM
- Università di Modena e Reggio Emilia
- 411125 Modena
- Italy
- Istituto Nanoscienze - CNR
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Cornia A, Rigamonti L, Boccedi S, Clérac R, Rouzières M, Sorace L. Magnetic blocking in extended metal atom chains: a pentachromium(ii) complex behaving as a single-molecule magnet. Chem Commun (Camb) 2014; 50:15191-4. [DOI: 10.1039/c4cc06693f] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Collauto A, Mannini M, Sorace L, Barbon A, Brustolon M, Gatteschi D. A slow relaxing species for molecular spin devices: EPR characterization of static and dynamic magnetic properties of a nitronyl nitroxide radical. ACTA ACUST UNITED AC 2012. [DOI: 10.1039/c2jm35076a] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
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Allão RA, Jordão AK, Resende JALC, Cunha AC, Ferreira VF, Novak MA, Sangregorio C, Sorace L, Vaz MGF. Determination of the relevant magnetic interactions in low-dimensional molecular materials: the fundamental role of single crystal high frequency EPR. Dalton Trans 2011; 40:10843-50. [PMID: 21860868 DOI: 10.1039/c1dt10780a] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
A new one-dimensional copper(II) complex with formula [Cu(hfac)(2)(N(3)TEMPO)](n) (hfac = hexafluoroacetylacetonate and N(3)TEMPO = 4-azido-2,2,6,6-tetramethylpiperidine-1-oxyl) has been synthesized and investigated by X-ray crystallography, magnetometry and multifrequency single crystal EPR. The system crystallizes in the P1 space group with two non equivalent copper(II) ions in the unit cell, the two nitroxide radicals being coordinated to Cu(1) in axial positions. The copper(II) ions are bridged by N(3)TEMPO radicals resulting in a zig-zag chain structure. The magnetic susceptibility data were at first satisfactorily modeled assuming an alternating spin chain along the monodimensional covalent skeleton, with a ferromagnetic interaction between Cu(1) and the nitroxide moieties and a weaker antiferromagnetic interaction between these and Cu(2) (J(1) = -13.8 cm(-1), J(2) = +2.4 cm(-1)). However, single crystal EPR studies performed at the X- and W-band clearly demonstrate that the observed magnetic monodimensional character of the complex is actually due to the intermolecular contacts involving N(3)TEMPO ligands. This prompted us to fit the magnetic data using a consistent model, pointing out the fundamental role of single crystal EPR data in defining a correct model to describe the magnetic properties of molecular low dimensional systems.
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Affiliation(s)
- R A Allão
- Instituto de Química, Universidade Federal Fluminense, 24020-141, Niterói, RJ, Brazil
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9
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Castelli L, Fittipaldi M, Powell AK, Gatteschi D, Sorace L. Single crystal EPR study at 95 GHz of a large Fe based molecular nanomagnet: toward the structuring of magnetic nanoparticle properties. Dalton Trans 2011; 40:8145-55. [PMID: 21637875 DOI: 10.1039/c1dt10311c] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
A W-band single-crystal EPR study has been performed on a molecular cluster comprising 19 iron(III) ions bridged by oxo- hydroxide ions, Fe(19), in order to investigate magnetic nanosystems with a behavior in between the one of Magnetic NanoParticles (MNP) and that of Single Molecule Magnets (SMM). The Fe(19) has a disk-like shape: a planar Fe(7) core with a brucite (Mg(OH)(2)) structure enclosed in a "shell" of 12 Fe(III) ions. EPR and magnetic measurements revealed an S = 35/2 ground state with an S = 33/2 excited state lying ∼ 8 K above. The presence of other low-lying excited states was also envisaged. Rhombic Zero Field Splitting (ZFS) tensors were determined, the easy axes lying in the Fe(19) plane for both the multiplets. At particular temperatures and orientations, a partially resolved fine structure could be observed which could not be distinguished in powder spectra, due to orientation disorder. The similarities of the EPR behavior of Fe(19) and MNP, together with the accuracy of single crystal analysis, helped to shed light on spectral features observed in MNP spectra, that is a sharp line at g = 2 and a low intensity transition at g = 4. Moreover, a theoretical analysis has been used to estimate the contribution to the total magnetic anisotropy of core and surface; this latter is crucial in determining the easy axis-type anisotropy, alike that of MNP surface.
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Affiliation(s)
- L Castelli
- Dipartimento di Chimica U. Schiff and UdR INSTM, Università di Firenze, Via della Lastruccia 3-13, 50019, Sesto Fiorentino, Italy
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Dei A, Poneti G, Sorace L. Metal dilution effects on entropy and light-induced valence tautomeric interconversion in a 1:1 cobalt-dioxolene complex. Inorg Chem 2010; 49:3271-7. [PMID: 20196549 DOI: 10.1021/ic902255j] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The entropy and the light-induced valence tautomeric interconversions of solid solutions of the [Co(Me(2)tpa)(diox)](PF(6)).C(6)H(5)CH(3) complex [Me(2)tpa = bis(6-methyl-(2-pyridylmethyl))(2-pyridylmethyl)amine and diox = catecholato (DBCat) or semiquinonato (DBSQ) forms of 3,5-ditert-butylquinone] in the electronically innocent [Zn(Me(2)tpa)(DBSQ)](PF(6)).C(6)H(5)CH(3) host, in four different molar ratios, have been investigated. It has been found that the entropy driven transition is strongly affected by the Co:Zn molar ratio, whereas the relaxation rates of the optically induced high-spin Co(II)-DBSQ metastable state at cryogenic temperatures are nearly independent of the degree of solid dilution. These results are discussed in the framework of the Jortner theory for adiabatic radiationless multiphonon relaxation processes. It is suggested that the optical bistability in these systems is related to the single molecule properties rather than to the cooperative effects active in the lattice.
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Affiliation(s)
- A Dei
- Laboratory of Molecular Magnetism (LAMM), Department of Chemistry, Ugo Schiff and INSTM Research Unit, University of Florence, Via della Lastruccia, 3-13, 50019 Sesto Fiorentino, Florence, Italy.
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Fittipaldi M, Sorace L, Barra AL, Sangregorio C, Sessoli R, Gatteschi D. Molecular nanomagnets and magnetic nanoparticles: the EMR contribution to a common approach. Phys Chem Chem Phys 2009; 11:6555-68. [PMID: 19639130 DOI: 10.1039/b905880j] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The current status and future developments of the use of electron magnetic resonance (EMR) for the investigation of magnetic nano-systems is here reviewed. The aim is to stimulate efforts to provide a unified view of the properties of magnetic nanoparticles (MNP) comprising a few hundred magnetic centres, and molecular nanomagnets which contain up to ca. one hundred magnetic centres (MNM). The size of the systems is becoming the same but the approaches to the interpretation of their properties are still different, being bottom up for the latter and top down for the former. We make the point here of the need for a common viewpoint, highlighting the status of the two fields and giving some hints for the future developments. EMR has been a powerful tool for the investigation of magnetic nano-objects and it can provide a tool of fundamental importance for the development of a unified view.
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Affiliation(s)
- M Fittipaldi
- Department of Chemistry, University of Florence, via della Lastruccia, 3 50019 Sesto Fiorentino, Italy.
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Barra AL, Gatteschi D, Sessoli R, Sorace L. High-field/high-frequency EPR studies of spin clusters with integer spin: the multi-frequency approach. Magn Reson Chem 2005; 43 Spec no.:S183-91. [PMID: 16235216 DOI: 10.1002/mrc.1695] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/04/2023]
Abstract
In this paper a rapid overview of the main results obtained from the study with multi-frequency HF-EPR of molecular spin clusters possessing integer spin values is presented. In the first part, two antiferromagnetic rings with zero ground spin state are reported. It is illustrated how the HF-EPR study of the first excited states allows obtaining important information on this kind of spin clusters. In the second part, selected examples of single-molecule magnets (SMM) are treated, starting with complexes involving only a few magnetic ions and going on to more complex systems. Indeed, because of their large zero-field energy gaps, EPR studies of SMM deserve the use of high frequencies and high fields. The approach presented here is twofold. First the interest of studying a series of 'simple' SMM in order to understand the subtle mechanisms underlying their properties is stressed. Then a summary of our HF-EPR studies of the most investigated SMM, Mn12ac and Fe8 is presented.
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Affiliation(s)
- A-L Barra
- Grenoble High Magnetic Field Laboratory, CNRS, B.P. 166, 38042 Grenoble Cedex 9, France.
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Cornia A, Sessoli R, Sorace L, Gatteschi D, Barra AL, Daiguebonne C. Origin of second-order transverse magnetic anisotropy in Mn12-acetate. Phys Rev Lett 2002; 89:257201. [PMID: 12484911 DOI: 10.1103/physrevlett.89.257201] [Citation(s) in RCA: 67] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/06/2001] [Indexed: 05/24/2023]
Abstract
The symmetry breaking effects for quantum tunneling of the magnetization in Mn12-acetate, a molecular nanomagnet, represent an open problem. We present structural evidence that the disorder of the acetic acid of crystallization induces sizable distortion of the Mn(III) sites, giving rise to six different isomers. Four isomers have symmetry lower than tetragonal and a nonzero second-order transverse magnetic anisotropy, which has been evaluated using a ligand field approach. The result of the calculation leads to an improved simulation of electron paramagnetic resonance spectra and justifies the tunnel splitting distribution derived from the field sweep rate dependence of the hysteresis loops.
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Affiliation(s)
- A Cornia
- Dipartimento di Chimica and INSTM, Università di Modena e Reggio Emilia, via G. Campi 183, Italy
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Brunel LC, Caneschi A, Dei A, Friselli D, Gatteschi D, Hassan AK, Lenci L, Martinelli M, Massa CA, Pardi LA, Popescu F, Ricci I, Sorace L. How and why the characterization of magnetic materials can give directions in the methodological development in high field–high frequency EPR. Res Chem Intermed 2002. [DOI: 10.1163/156856702320267127] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
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Caneschi A, Gatteschi D, Lalioti N, Sessoli R, Sorace L, Tangoulis V, Vindigni A. Ising-type magnetic anisotropy in a cobalt(II) nitronyl nitroxide compound: a key to understanding the formation of molecular magnetic nanowires. Chemistry 2002; 8:286-92. [PMID: 11822459 DOI: 10.1002/1521-3765(20020104)8:1<286::aid-chem286>3.0.co;2-d] [Citation(s) in RCA: 97] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
The compound [Co(hfac)2-(NITPhOMe)2] (2) (hfac = hexafluoroacetylacetonate, NITPhOMe = 4'-methoxyphenyl-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide) crystallizes in the triclinic P1 space group, a= 10.870(5), b = 11.520(5), c = 19.749(5) A, alpha = 78.05(5), beta = 84.20(5), gamma = 64.51(5) degrees, Z = 2. It can be considered a model system for studying the nature of the magnetic anisotropy of [Co(hfac)2(NITPhOMe)] (1), which was recently reported to behave as a molecular magnetic wire. The magnetic anisotropy of 2 was investigated by EPR spectroscopy and SQUID magnetometry both in the polycrystalline powder and in a single crystal. The experimental magnetic anisotropy was related to the anisotropy of the central ion and to the exchange interaction between the cobalt(II) ion and the radicals.
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Affiliation(s)
- A Caneschi
- Dipartimento di Chimica, Università degli Studi di Firenze and INSTM, U.d.R. Firenze, Italy
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Caneschi A, Gatteschi D, Lalioti N, Sessoli R, Sorace L, Tangoulis V, Vindigni A. Ising-Type Magnetic Anisotropy in a Cobalt(II) Nitronyl Nitroxide Compound: A Key to Understanding the Formation of Molecular Magnetic Nanowires. Chemistry 2002. [DOI: 10.1002/1521-3765(20020104)8:1%3c286::aid-chem286%3e3.0.co;2-d] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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Lee D, Sorace L, Caneschi A, Lippard SJ. Hydroxo-bridged Cubane-type tetrairon(II) clusters supported by sterically-hindered carboxylate ligands. Inorg Chem 2001; 40:6774-81. [PMID: 11735490 DOI: 10.1021/ic010726b] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
A series of hydroxo-bridged cubane-type tetrairon(II) clusters, [Fe(4)(mu-OH)(4)(mu-O(2)CAr(4)(-)t(BuPh))(2)(mu-OTf)(2)L(4)] (L = C(5)H(5)N (1), 4-(t)BuC(5)H(4)N (2), 3-FC(5)H(4)N (3)), were synthesized by using a sterically hindered carboxylate ligand, 2,6-di(4-tert-butylphenyl)benzoate (Ar(4)(-)t(BuPh)CO(2)(-)). Three different bridging units that mediate weak antiferromagnetic coupling interactions between the metal centers support the unprecedented cubane-type [Fe(4)(mu-OH)(4)](4+) cores in 1-3. The solution structures of 1 and 3 probed by FT-IR and (19)F NMR spectroscopy are consistent with the solid-state geometry determined by X-ray crystallography. Zero-field Mössbauer spectra of 1-3 at 4.2 K are characteristic of high-spin iron(II) centers in nearly identical coordination environments. Compound 1 undergoes two irreversible oxidation processes at ca -10 and +880 mV (vs Fc/Fc(+)), the former approaching quasi-reversible behavior with increased scan rates and a narrow potential sweep range. Comparisons are made with analogous known [Fe(4)X(4)](n)()(+) (X = O, S) units, and the structural integrity of tetrairon fragments upon a change in oxidation state is discussed together with some possible biological implications.
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Affiliation(s)
- D Lee
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
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Bodnar SH, Caneschi A, Dei A, Shultz DA, Sorace L. A bis-bidentate dioxolene ligand induces thermal hysteresis in valence tautomerism interconversion processes. Chem Commun (Camb) 2001:2150-1. [PMID: 12240207 DOI: 10.1039/b106192p] [Citation(s) in RCA: 49] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The use of a bis-bidentate ligand in a solid cobalt dioxolene complex affords the necessary cooperative properties that lead to thermal hysteresis in a valence tautomeric interconversion equilibrium.
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Affiliation(s)
- S H Bodnar
- Department of Chemistry, North Carolina State University, Raleigh, North Carolina, USA
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Bencini A, Daul CA, Dei A, Mariotti F, Lee H, Shultz DA, Sorace L. Charge distribution in bis-dioxolene radical metal complexes. synthesis and DFT characterization of dinuclear Co(III) and Cr(III) complexes with a mixed-valent, S = 1/2 semiquinone-catecholate ligand. Inorg Chem 2001; 40:1582-90. [PMID: 11261968 DOI: 10.1021/ic0007052] [Citation(s) in RCA: 50] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Bis-dioxolene bridged dinuclear metal complexes of general formula M2(CTH)2(diox-diox)(PF6)n (n = 2, 3; M = Co(III), Cr(III); CTH = tetraazamacrocycle) have been synthesized using the bis-bidentate ligand 5,5'-di-tert-butyl-3,3',4,4'-tetrahydroxybiphenyl. These complexes were characterized by means of ESR, UV-vis, temperature dependent magnetic susceptibility, and cyclic voltammetry. Our results unambiguously suggest that the tripositive dimetal cations can be described as containing a fully delocalized bis-dioxolene trinegative radical ligand (Cat-Sq) bridging two tripositive metal cations. In this frame the sextet electronic ground state characterizes the Cr2(CTH)2(Cat-SQ)3+ as a result of the antiferromagnetic coupling of the radical bridging ligand with the two equivalent paramagnetic metal centers. The electronic and geometrical structure and the magnetic properties of Cat-Sq and of its complexes have been studied with density functional theory.
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Affiliation(s)
- A Bencini
- Dipartimento di Chimica, Università di Firenze, Firenze, Italy
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Caneschi A, Dei A, Lee H, Shultz DA, Sorace L. Ferromagnetically coupled bis(semiquinone) ligand enforces high-spin ground states in bis-metal complexes. Inorg Chem 2001; 40:408-11. [PMID: 11170550 DOI: 10.1021/ic000440r] [Citation(s) in RCA: 53] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- A Caneschi
- Dipartimento di Chimica dell'Università, Via Maragliano 75-50144, Firenze, Italy
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21
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Dei A, Gatteschi D, Massa CA, Pardi LA, Poussereau S, Sorace L. Spontaneous symmetry breaking in the formation of a dinuclear gadolinium semiquinonato complex: synthesis, high-field EPR studies, and magnetic properties. Chemistry 2000; 6:4580-6. [PMID: 11192091 DOI: 10.1002/1521-3765(20001215)6:24<4580::aid-chem4580>3.0.co;2-b] [Citation(s) in RCA: 53] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
The synthesis and characterisation of an asymmetric dinuclear gadolinium(III) semiquinonato complex, namely [Gd2(HBPz3)2(dtbsq)4] CHCl3 (1; HBPz3 = hydrotris(pyrazolyl)borate, dtbsq = 3,5-di-tert-butyl-O-semiquinone), is reported. The crystal structure of 1 was determined at room temperature. It crystallises in the triclinic system P1, with a = 16.735(5) A, b = 17.705(5) A, c = 19.553(5) A, alpha = 99.680(5) degrees, beta = 109.960(5), gamma = 107.350(5) degrees, Z = 2 and R = 9.96. The structure of 1 consists of a dinuclear asymmetric unit in which the two gadolinium(III) ions have coordination numbers of eight and nine. Three of the dioxolene molecules act as asymmetric bridging ligands, while the fourth molecule behaves as a bidentate ligand towards a single metal ion. The magnetic properties of 1 were investigated by means of susceptibility measurements and high-field electron paramagnetic resonance (HF-EPR) spectroscopy. They revealed an S = 0 ground spin state with excited states of higher spin very close in energy and a small negative zero-field splitting with a transverse anisotropy term for a S = 7 state.
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Affiliation(s)
- A Dei
- Dipartimento di Chimica università di Firenze, Italy
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Barra AL, Caneschi A, Cornia A, Fabrizi de Biani F, Gatteschi D, Sangregorio C, Sessoli R, Sorace L. Single-Molecule Magnet Behavior of a Tetranuclear Iron(III) Complex. The Origin of Slow Magnetic Relaxation in Iron(III) Clusters. J Am Chem Soc 1999. [DOI: 10.1021/ja9818755] [Citation(s) in RCA: 402] [Impact Index Per Article: 16.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- A. L. Barra
- Contribution from the Department of Chemistry, University of Florence, Via Maragliano 77, I-50144 Firenze, Italy, Department of Chemistry, University of Modena, Via G. Campi 183, I-41100 Modena, Italy, and High Magnetic Field Laboratory, MPI-CNRS, B.P. 166, 38042 Grenoble, France
| | - A. Caneschi
- Contribution from the Department of Chemistry, University of Florence, Via Maragliano 77, I-50144 Firenze, Italy, Department of Chemistry, University of Modena, Via G. Campi 183, I-41100 Modena, Italy, and High Magnetic Field Laboratory, MPI-CNRS, B.P. 166, 38042 Grenoble, France
| | - A. Cornia
- Contribution from the Department of Chemistry, University of Florence, Via Maragliano 77, I-50144 Firenze, Italy, Department of Chemistry, University of Modena, Via G. Campi 183, I-41100 Modena, Italy, and High Magnetic Field Laboratory, MPI-CNRS, B.P. 166, 38042 Grenoble, France
| | - F. Fabrizi de Biani
- Contribution from the Department of Chemistry, University of Florence, Via Maragliano 77, I-50144 Firenze, Italy, Department of Chemistry, University of Modena, Via G. Campi 183, I-41100 Modena, Italy, and High Magnetic Field Laboratory, MPI-CNRS, B.P. 166, 38042 Grenoble, France
| | - D. Gatteschi
- Contribution from the Department of Chemistry, University of Florence, Via Maragliano 77, I-50144 Firenze, Italy, Department of Chemistry, University of Modena, Via G. Campi 183, I-41100 Modena, Italy, and High Magnetic Field Laboratory, MPI-CNRS, B.P. 166, 38042 Grenoble, France
| | - C. Sangregorio
- Contribution from the Department of Chemistry, University of Florence, Via Maragliano 77, I-50144 Firenze, Italy, Department of Chemistry, University of Modena, Via G. Campi 183, I-41100 Modena, Italy, and High Magnetic Field Laboratory, MPI-CNRS, B.P. 166, 38042 Grenoble, France
| | - R. Sessoli
- Contribution from the Department of Chemistry, University of Florence, Via Maragliano 77, I-50144 Firenze, Italy, Department of Chemistry, University of Modena, Via G. Campi 183, I-41100 Modena, Italy, and High Magnetic Field Laboratory, MPI-CNRS, B.P. 166, 38042 Grenoble, France
| | - L. Sorace
- Contribution from the Department of Chemistry, University of Florence, Via Maragliano 77, I-50144 Firenze, Italy, Department of Chemistry, University of Modena, Via G. Campi 183, I-41100 Modena, Italy, and High Magnetic Field Laboratory, MPI-CNRS, B.P. 166, 38042 Grenoble, France
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