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Sojka A, Price BD, Sherwin MS. Order-of-magnitude SNR improvement for high-field EPR spectrometers via 3D printed quasi-optical sample holders. SCIENCE ADVANCES 2023; 9:eadi7412. [PMID: 37729398 PMCID: PMC10511183 DOI: 10.1126/sciadv.adi7412] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/18/2023] [Accepted: 08/18/2023] [Indexed: 09/22/2023]
Abstract
Here, we present a rapidly prototyped, cost-efficient, and 3D printed quasi-optical sample holder for improving the signal-to-noise ratio (SNR) in modern, resonator-free, and high-field electron paramagnetic resonance (HFEPR) spectrometers. Such spectrometers typically operate in induction mode: The detected EPR ("cross-polar") signal is polarized orthogonal to the incident ("co-polar") radiation. The sample holder makes use of an adjustable sample positioner that allows for optimizing the sample position to maximize the 240-gigahertz magnetic field B1 and a rooftop mirror that allows for small rotations of the microwave polarization to maximize the cross-polar signal and minimize the co-polar background. When optimally tuned, the sample holder was able to improve co-polar isolation by ≳20 decibels, which is proven beneficial for maximizing the SNR in rapid-scan, pulsed, and continuous-wave EPR experiments. In rapid-scan mode, the improved SNR enabled the recording of entire EPR spectra of a narrow-line radical in millisecond time scales, which, in turn, enabled real-time monitoring of a sample's evolving line shape.
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Affiliation(s)
- Antonín Sojka
- Department of Physics, University of California, Santa Barbara, Santa Barbara, CA, USA
- Institute for Terahertz Science and Technology, University of California, Santa Barbara, Santa Barbara, CA 93106, USA
| | - Brad D. Price
- Department of Physics, University of California, Santa Barbara, Santa Barbara, CA, USA
- Institute for Terahertz Science and Technology, University of California, Santa Barbara, Santa Barbara, CA 93106, USA
| | - Mark S. Sherwin
- Department of Physics, University of California, Santa Barbara, Santa Barbara, CA, USA
- Institute for Terahertz Science and Technology, University of California, Santa Barbara, Santa Barbara, CA 93106, USA
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2
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Nehrkorn J, Greer SM, Malbrecht BJ, Anderton KJ, Aliabadi A, Krzystek J, Schnegg A, Holldack K, Herrmann C, Betley TA, Stoll S, Hill S. Spectroscopic Investigation of a Metal-Metal-Bonded Fe 6 Single-Molecule Magnet with an Isolated S = 19/ 2 Giant-Spin Ground State. Inorg Chem 2021; 60:4610-4622. [PMID: 33683105 DOI: 10.1021/acs.inorgchem.0c03595] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The metal-metal-bonded molecule [Bu4N][(HL)2Fe6(dmf)2] (Fe6) was previously shown to possess a thermally isolated spin S = 19/2 ground state and found to exhibit slow magnetization relaxation below a blocking temperature of ∼5 K [J. Am. Chem. Soc. 2015, 137, 13949-13956]. Here, we present a comprehensive spectroscopic investigation of this unique single-molecule magnet (SMM), combining ultrawideband field-swept high-field electron paramagnetic resonance (EPR) with frequency-domain Fourier-transform terahertz EPR to accurately quantify the spin Hamiltonian parameters of Fe6. Of particular importance is the near absence of a 4th-order axial zero-field splitting term, which is known to arise because of quantum mechanical mixing of spin states on account of the relatively weak spin-spin (superexchange) interactions in traditional polynuclear SMMs such as the celebrated Mn12-acetate. The combined high-resolution measurements on both powder samples and an oriented single crystal provide a quantitative measure of the isolated nature of the spin ground state in the Fe6 molecule, as well as additional microscopic insights into factors that govern the quantum tunneling of its magnetization. This work suggests strategies for improving the performance of polynuclear SMMs featuring direct metal-metal bonds and strong ferromagnetic spin-spin (exchange) interactions.
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Affiliation(s)
- Joscha Nehrkorn
- National High Magnetic Field Laboratory, Florida State University, Tallahassee, Florida 32310, United States.,Department of Chemistry, Institute for Inorganic and Applied Chemistry, University of Hamburg, Martin-Luther-King-Platz 6, 20146 Hamburg, Germany.,Department of Chemistry, University of Washington, Box 351700, Seattle, Washington 98195, United States.,Max Planck Institute for Chemical Energy Conversion, Stiftstraße 34-36, 45470 Mülheim an der Ruhr, Germany
| | - Samuel M Greer
- National High Magnetic Field Laboratory, Florida State University, Tallahassee, Florida 32310, United States.,Department of Chemistry and Biochemistry, Florida State University, Tallahassee, Florida 32306, United States
| | - Brian J Malbrecht
- Department of Chemistry and Chemical Biology, Harvard University, 12 Oxford Street, Cambridge, Massachusetts 02138, United States
| | - Kevin J Anderton
- Department of Chemistry and Chemical Biology, Harvard University, 12 Oxford Street, Cambridge, Massachusetts 02138, United States
| | - Azar Aliabadi
- Berlin Joint EPR Laboratory, Institut für Nanospektroskopie, Helmholtz-Zentrum Berlin für Materialien und Energie, Kekuléstraße 5, Berlin 12489, Germany
| | - J Krzystek
- National High Magnetic Field Laboratory, Florida State University, Tallahassee, Florida 32310, United States
| | - Alexander Schnegg
- Max Planck Institute for Chemical Energy Conversion, Stiftstraße 34-36, 45470 Mülheim an der Ruhr, Germany.,Berlin Joint EPR Laboratory, Institut für Nanospektroskopie, Helmholtz-Zentrum Berlin für Materialien und Energie, Kekuléstraße 5, Berlin 12489, Germany
| | - Karsten Holldack
- Institut für Methoden und Instrumentierung der Forschung mit Synchrotronstrahlung, Helmholtz-Zentrum Berlin für Materialen und Energie, Albert-Einstein-Straße 15, Berlin 12489, Germany
| | - Carmen Herrmann
- Department of Chemistry, Institute for Inorganic and Applied Chemistry, University of Hamburg, Martin-Luther-King-Platz 6, 20146 Hamburg, Germany
| | - Theodore A Betley
- Department of Chemistry and Chemical Biology, Harvard University, 12 Oxford Street, Cambridge, Massachusetts 02138, United States
| | - Stefan Stoll
- Department of Chemistry, University of Washington, Box 351700, Seattle, Washington 98195, United States
| | - Stephen Hill
- National High Magnetic Field Laboratory, Florida State University, Tallahassee, Florida 32310, United States.,Department of Physics, Florida State University, Tallahassee 32306, Florida, United States
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Das Gupta S, Stewart RL, Chen DT, Abboud KA, Cheng HP, Hill S, Christou G. Long-Range Ferromagnetic Exchange Interactions Mediated by Mn-Ce IV-Mn Superexchange Involving Empty 4f Orbitals. Inorg Chem 2020; 59:8716-8726. [PMID: 32573216 DOI: 10.1021/acs.inorgchem.0c00332] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Reactions involving reductive aggregation of MnO4- in methanol in the presence of CeIV and an excess of carboxylic acid have led to the synthesis of structurally related Ce/Mn clusters, [Ce3Mn5O8(OMe)(O2CBut)13(MeOH)] (1) and [Ce2Mn3O5(O2CPh)9(MeOH)3] (2), containing at least one {Mn2Ce2O4} cubane unit. The cores of both clusters contain Mnx units separated by three (1) or two (2) CeIV ions. Fits of variable-temperature, solid-state dc and ac magnetic susceptibility data reveal dominant ferromagnetic interactions within 1 and 2, resulting in the maximum S = 17/2 and S = 5 ground state spins, respectively, and thus suggesting significant ferromagnetic (F) interactions between the Mnx units that are ≥6 Å apart and separated by four intervening bonds through diamagnetic CeIV. Fits of magnetic susceptibility data also revealed unusual long-range F interactions, and this finding was further supported by high-field EPR measurements and simulations. Density functional theory calculations and a Wannier function analysis confirm long-range interactions and indicate a Mn-Ce-Mn superexchange pathway via Mn-d/Ce-f orbital overlap/hybridization.
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Affiliation(s)
- Sayak Das Gupta
- Department of Chemistry, University of Florida, Gainesville, Florida 32611, United States
| | - Robert L Stewart
- National High Magnetic Field Laboratory and Department of Physics, Florida State University, Tallahassee, Florida 32310, United States
| | - Dian-Teng Chen
- Department of Physics, University of Florida, Gainesville, Florida 32611, United States
| | - Khalil A Abboud
- Department of Chemistry, University of Florida, Gainesville, Florida 32611, United States
| | - Hai-Ping Cheng
- Department of Physics, University of Florida, Gainesville, Florida 32611, United States
| | - Stephen Hill
- National High Magnetic Field Laboratory and Department of Physics, Florida State University, Tallahassee, Florida 32310, United States
| | - George Christou
- Department of Chemistry, University of Florida, Gainesville, Florida 32611, United States
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4
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Kalofolias DA, Flamourakis AG, Siczek M, Lis T, Milios CJ. A bulky oxime for the synthesis of Mn(III) clusters. J COORD CHEM 2015. [DOI: 10.1080/00958972.2015.1075014] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
Affiliation(s)
| | | | - Milosz Siczek
- Faculty of Chemistry, University of Wroclaw, Wroclaw, Poland
| | - Tadeusz Lis
- Faculty of Chemistry, University of Wroclaw, Wroclaw, Poland
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5
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Milios CJ, Winpenny REP. Cluster-Based Single-Molecule Magnets. MOLECULAR NANOMAGNETS AND RELATED PHENOMENA 2014. [DOI: 10.1007/430_2014_149] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
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Martínez-Lillo J, Mastropietro TF, Lhotel E, Paulsen C, Cano J, De Munno G, Faus J, Lloret F, Julve M, Nellutla S, Krzystek J. Highly Anisotropic Rhenium(IV) Complexes: New Examples of Mononuclear Single-Molecule Magnets. J Am Chem Soc 2013; 135:13737-48. [DOI: 10.1021/ja403154z] [Citation(s) in RCA: 91] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Affiliation(s)
- José Martínez-Lillo
- Departament
de Química Inorgànica/Instituto de Ciencia Molecular
(ICMol), Universitat de València, C/Catedrático José
Beltrán 2, 46980 Paterna (València), Spain
| | - Teresa F. Mastropietro
- Centro
di Eccellenza CEMIF.CAL, Dipartimento di Chimica, Università della Calabria, 87030 Arcavacata di Rende, Cosenza, Italy
| | - Elsa Lhotel
- Institut Néel-CNRS, BP
166, 25 Avenue des Martyrs, 38042 Grenoble Cedex 9, France
| | - Carley Paulsen
- Institut Néel-CNRS, BP
166, 25 Avenue des Martyrs, 38042 Grenoble Cedex 9, France
| | - Joan Cano
- Departament
de Química Inorgànica/Instituto de Ciencia Molecular
(ICMol), Universitat de València, C/Catedrático José
Beltrán 2, 46980 Paterna (València), Spain
- Fundació
General de la Universitat de València (FGUV), Universitat de València, 46010 València, Spain
| | - Giovanni De Munno
- Centro
di Eccellenza CEMIF.CAL, Dipartimento di Chimica, Università della Calabria, 87030 Arcavacata di Rende, Cosenza, Italy
| | - Juan Faus
- Departament
de Química Inorgànica/Instituto de Ciencia Molecular
(ICMol), Universitat de València, C/Catedrático José
Beltrán 2, 46980 Paterna (València), Spain
| | - Francesc Lloret
- Departament
de Química Inorgànica/Instituto de Ciencia Molecular
(ICMol), Universitat de València, C/Catedrático José
Beltrán 2, 46980 Paterna (València), Spain
| | - Miguel Julve
- Departament
de Química Inorgànica/Instituto de Ciencia Molecular
(ICMol), Universitat de València, C/Catedrático José
Beltrán 2, 46980 Paterna (València), Spain
| | - Saritha Nellutla
- National
High Magnetic Field Laboratory, Florida State University, Tallahassee, Florida 32310, United States
| | - J. Krzystek
- National
High Magnetic Field Laboratory, Florida State University, Tallahassee, Florida 32310, United States
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Martínez-Lillo J, Tomsa AR, Li Y, Chamoreau LM, Cremades E, Ruiz E, Barra AL, Proust A, Verdaguer M, Gouzerh P. Synthesis, crystal structure and magnetism of new salicylamidoxime-based hexanuclear manganese(III) single-molecule magnets. Dalton Trans 2012; 41:13668-81. [PMID: 22930397 DOI: 10.1039/c2dt31443f] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
Salicylamidoxime was used to synthesize 13 new polynuclear Mn(III) complexes. We present the crystallographic structures, the magnetic susceptibility and the magnetization measurements of eight of them (1-8) with the general formula [Mn(6)O(2)(H(2)N-sao)(6)(L)(2)(solvent)(4-6)] (L = carboxylate, chloride, 2-cyanophenolate; solvent = H(2)O, MeOH, EtOH, py). These complexes consist of two trinuclear {Mn(III)(3)(μ(3)-O)(H(2)N-sao)(3)}(+) cationic units linked together via two oximate and two phenolate oxygen atoms. All behave as single-molecule magnets, with the spin ground state varying from 4 to 12 and anisotropy energy barriers from 24 to 86 K, the latter being as high as the present record barrier in the Mn(6) complexes. DFT calculations were performed to compute the exchange magnetic coupling constants J between the metallic ions and to provide an orbital interpretation of exchange. Our results are in line with previously reported results with the parent salicylaldoxime derivatives. The Mn-N-O-Mn torsion angle appears as the main parameter controlling the J values. The critical angle where the exchange coupling between two Mn(III) switches from antiferromagnetic to ferromagnetic is 27°, less than the one found in related complexes with salicylaldoxime (30°). We propose a structural classification of the {Mn(6)} complexes in four classes depending on the coordination of the axial carboxylate. The work points out the structural flexibility of such systems, their sensitivity to solvent effects and their ability to achieve high anisotropy energy barriers by simple desolvation.
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Affiliation(s)
- José Martínez-Lillo
- Institut Parisien de Chimie Moléculaire, UMR CNRS 7201, UPMC Université Paris 06, Case courrier 42, 4 Place Jussieu, 75252 Paris Cedex 05, France
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Inglis R, Milios CJ, Jones LF, Piligkos S, Brechin EK. Twisted molecular magnets. Chem Commun (Camb) 2011; 48:181-90. [PMID: 21892459 DOI: 10.1039/c1cc13558a] [Citation(s) in RCA: 87] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The use of derivatised salicylaldoximes in manganese chemistry has led to the synthesis of a family of approximately fifty hexanuclear ([Mn(III)(6)]) and thirty trinuclear ([Mn(III)(3)]) Single-Molecule Magnets (SMMs). Deliberate, targeted structural distortion of the metallic core afforded family members with increasingly puckered configurations, leading to a switch in the pairwise magnetic exchange from antiferromagnetic to ferromagnetic. Examination of both the structural and magnetic data revealed a semi-quantitative magneto-structural correlation, from which the factors governing the magnetic properties could be extracted and used for predicting the properties of new family members and even more complicated structures containing analogous building blocks. Herein we describe an overview of this extensive body of work and discuss its potential impact on similar systems.
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Affiliation(s)
- Ross Inglis
- EaStChem School of Chemistry, The University of Edinburgh, The Kings Buildings, West Mains Road, Edinburgh, EH9 3JJ, UK
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Lampropoulos C, Hill S, Christou G. A Caveat for Single-Molecule Magnetism: Non-linear Arrhenius Plots. Chemphyschem 2009; 10:2397-400. [DOI: 10.1002/cphc.200900420] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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Inglis R, Taylor SM, Jones LF, Papaefstathiou GS, Perlepes SP, Datta S, Hill S, Wernsdorfer W, Brechin EK. Twisting, bending, stretching: strategies for making ferromagnetic [Mn(III)3] triangles. Dalton Trans 2009:9157-68. [PMID: 20449192 DOI: 10.1039/b911820a] [Citation(s) in RCA: 85] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The synthesis and characterisation of a large family of trimetallic [Mn(III)(3)] Single-Molecule Magnets is presented. The complexes reported can be divided into three categories with general formulae (type 1) [Mn(III)(3)O(R-sao)(3)(X)(sol)(3-4)] (where R = H, Me, (t)Bu; X = (-)O(2)CR (R = H, Me, Ph etc); sol = py and/or H(2)O), (type 2) [Mn(III)(3)O(R-sao)(3)(X)(sol)(3-5)] (where R = Me, Et, Ph, (t)Bu; X = (-)O(2)CR (R = H, Me, Ph etc); sol = MeOH, EtOH and/or H(2)O), and (type 3) [Mn(III)(3)O(R-sao)(3)(sol)(3)(XO(4))] (where R = H, Et, Ph, naphth; sol = py, MeOH, beta-pic, Et-py, (t)Bu-py; X = Cl, Re). We show that deliberate structural distortions of the molecule can be used to tune the observed magnetic properties. In the crystals the ferromagnetic triangles are involved in extensive inter-molecular H-bonding which is clearly manifested in the magnetic behaviour, producing exchange-biased SMMs. These interactions can be removed by ligand replacement to give "simpler" SMMs.
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Affiliation(s)
- Ross Inglis
- School of Chemistry, The University of Edinburgh, West Mains Road, Edinburgh, UK EH9 3JJ
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Inglis R, Jones LF, Milios CJ, Datta S, Collins A, Parsons S, Wernsdorfer W, Hill S, Perlepes SP, Piligkos S, Brechin EK. Attempting to understand (and control) the relationship between structure and magnetism in an extended family of Mn6 single-molecule magnets. Dalton Trans 2009:3403-12. [DOI: 10.1039/b822235e] [Citation(s) in RCA: 141] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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