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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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Tubau À, Zinna F, Di Bari L, Font-Bardía M, Vicente R. Luminescence, CPL and magnetic properties of 1D enantiopure Ln 3+ complexes with ( S-) and ( R-) α-methoxyphenylacetate ligand. Dalton Trans 2023; 52:1122-1132. [PMID: 36606358 DOI: 10.1039/d2dt03356a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
The reaction of Ln(NO3)2·6H2O (Ln = Eu, Tb, Dy and Sm) with (R)-(-)-α-methoxyphenylacetic acid (R-HMPA) and 1,10-phenanthroline (phen) in EtOH/H2O allows the isolation of 1D chiral compounds of formula [Ln(μ-R-MPA)(R-MPA)2(phen)]n in which Ln = Eu (R-Eu), Tb (R-Tb), Dy (R-Dy) and Sm (R-Sm). The same synthesis by using (S)-(+)-α-methoxyphenylacetic acid (S-HMPA) instead of (R)-(-)-α-methoxyphenylacetic acid allows the isolation of the enantiomeric compounds with formula [Ln(μ-S-MPA)(S-MPA)2(phen)]n where Ln = Eu (S-Eu), Tb (S-Tb), Dy (S-Dy) and Sm (S-Sm). Single crystal X-Ray diffraction measurements were performed for compounds R/S-Eu, R/S-Tb, S-Dy and S-Sm. The luminescence and the circular dichroism measured in the solid state are reported. All compounds show sensitized luminescence, notably the Eu3+ and Tb3+ ones, whose emission color can be perceived by the naked eye. For the Eu3+ and Tb3+ derivatives the quantum yield and the circular polarized luminescence have been measured. For the magnetic allowed transition 5D0 → 7F1 of the Eu3+ compound, the anisotropy factor glum is ±0.013 (+for S-Eu). Also, magnetic properties of all compounds were studied with the Dy3+ analogue showing slow relaxation of the magnetization under a direct current magnetic field of 1000 Oe.
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Affiliation(s)
- Ànnia Tubau
- Departament de Química Inorgànica i Orgànica, Secció de Química Inorgànica, Universitat de Barcelona, Martí i Franquès 1-11, 08028 Barcelona, Spain.
| | - Francesco Zinna
- Dipartimento di Chimica e Chimica Industriale, Università di Pisa, via Moruzzi 13, I 56124 Pisa, Italy.
| | - Lorenzo Di Bari
- Dipartimento di Chimica e Chimica Industriale, Università di Pisa, via Moruzzi 13, I 56124 Pisa, Italy.
| | - Mercè Font-Bardía
- Departament de Mineralogia, Cristal lografia i Dipòsits Minerals and Unitat de Difracció de Raigs X. Centres Científics i Tecnològics de la Universitat de Barcelona (CCiTUB). Universitat de Barcelona, Solé i Sabarís 1-3, 08028 Barcelona, Spain
| | - Ramon Vicente
- Departament de Química Inorgànica i Orgànica, Secció de Química Inorgànica, Universitat de Barcelona, Martí i Franquès 1-11, 08028 Barcelona, Spain.
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Dunstan MA, Brown DS, Sorace L, Mole RA, Boskovic C. Modulation of Slow Magnetic Relaxation in Gd(III)-Tetrahalosemiquinonate Complexes. Chem Asian J 2022; 17:e202200325. [PMID: 35644855 PMCID: PMC9400849 DOI: 10.1002/asia.202200325] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2022] [Revised: 05/26/2022] [Indexed: 11/20/2022]
Abstract
Incorporating lanthanoid(III)-radical magnetic exchange coupling is a possible route to improving the performance of lanthanoid (Ln) single-molecule magnets (SMMs), molecular materials that exhibit slow relaxation and low temperature quantum tunnelling of the magnetization. Complexes of Gd(III) can conveniently be used as model systems to study the Ln-radical exchange coupling, thanks to the absence of the orbital angular momentum that is present for many Ln(III) ions. Two new Gd(III)-radical compounds of formula [Gd(18-c-6)X4 SQ(NO3 )].I3 (18-c-6=18-crown-6, X4 SQ⋅- =tetrahalo-1,2-semiquinonate, 1: X=Cl, 2: X=Br) have been synthesized, and the presence of the dioxolene ligand in its semiquinonate form confirmed by X-ray crystallography, UV-Visible-NIR spectroscopy and voltammetry. Static magnetometry and EPR spectroscopy indicate differences in the low temperature magnetic properties of the two compounds, with antiferromagnetic exchange coupling of JGd-SQ ∼-2.0 cm-1 (Hex =-2JGd-SQ (SGd SSQ )) determined by data fitting. Interestingly, compound 1 exhibits slow magnetic relaxation in applied magnetic fields while 2 relaxes much faster, pointing to the major role of packing effects in modulating slow relaxation of the magnetization.
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Affiliation(s)
- Maja A. Dunstan
- School of ChemistryThe University of MelbourneParkvilleVIC3010Australia
| | - Dominic S. Brown
- School of ChemistryThe University of MelbourneParkvilleVIC3010Australia
| | - Lorenzo Sorace
- Department of Chemistry, “Ugo Schiff”Universita Degli Studi FirenzeVia della Lastruccia, 1350019Sesto FiorentinoItaly
| | - Richard A. Mole
- Australian Centre for Neutron ScatteringAustralian Nuclear Science and Technology OrganisationLocked Bag 2001Kirrawee DC2232Australia
| | - Colette Boskovic
- School of ChemistryThe University of MelbourneParkvilleVIC3010Australia
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One-Dimensional Gadolinium (III) Complexes Based on Alpha- and Beta-Amino Acids Exhibiting Field-Induced Slow Relaxation of Magnetization. INORGANICS 2022. [DOI: 10.3390/inorganics10030032] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
Gadolinium (III) complexes exhibiting slow relaxation of magnetization are uncommon and have been much less studied than other compounds based on anisotropic lanthanide (III) ions. We prepared two one-dimensional gadolinium (III) complexes based on α-glycine (gly) and β-alanine (β-ala) amino acids, with the formula {[Gd2(gly)6(H2O)4](ClO4)6·5H2O}n (1) and {[Gd2(β-ala)6(H2O)4](ClO4)6·H2O}n (2), which were magneto-structurally characterized. Compounds 1 and 2 crystallize in the triclinic system (space group Pī). In complex 1, two Gd (III) ions are eight-coordinate and bound to six oxygen atoms from six gly ligands and two oxygen atoms from two water molecules, the metal ions showing different geometries (bicapped trigonal prism and square antiprism). In complex 2, two Gd (III) ions are nine-coordinate and bound to seven oxygen atoms from six β-ala ligands and two oxygen atoms from two water molecules in the same geometry (capped square antiprism). Variable-temperature dc magnetic susceptibility measurements performed on microcrystalline samples of 1 and 2 show similar magnetic behavior for both compounds, with antiferromagnetic coupling between the Gd (III) ions connected through carboxylate groups. Ac magnetic susceptibility measurements reveal slow relaxation of magnetization in the presence of an external dc field in both compounds, hence indicating the occurrence of the field-induced single-molecule magnet (SMM) phenomenon in both 1 and 2.
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Slow magnetic relaxation in a 3D dysprosium(III)-fluoro-oxalate framework containing zig-zag [Dy-F] chains. J RARE EARTH 2022. [DOI: 10.1016/j.jre.2022.02.019] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
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Leng JD, Hua QY, Liu WT, Tao ZX, Tan NW, Wang YF, Lin WQ. Slow magnetic relaxation of mononuclear complexes based on uncommon Kramers lanthanide ions CeIII, SmIII and YbIII. Dalton Trans 2022; 51:12661-12669. [DOI: 10.1039/d2dt00766e] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Based on uncommon Kramers ions CeIII, SmIII and YbIII, complexes [Ce(dppbO2)2Cl3] (1, dppbO2 = 1,2-bis(diphenylphosphino)benzene dioxide), [Sm(dppbO2)2Cl3] (2) and [Yb(dppbO2)2Cl2]Cl (3) toward single-ion magnets were obtained and fully characterized. Complexes...
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The Underexplored Field of Lanthanide Complexes with Helicene Ligands: Towards Chiral Lanthanide Single Molecule Magnets. MAGNETOCHEMISTRY 2021. [DOI: 10.3390/magnetochemistry7100138] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
The effective combination of chirality and magnetism in a single crystalline material can lead to fascinating cross-effects, such as magneto-chiral dichroism. Among a large variety of chiral ligands utilized in the design and synthesis of chiral magnetic materials, helicenes seem to be the most appealing ones, due to the exceptionally high specific rotation values that reach thousands of deg·cm3·g−1·dm−1, which is two orders of magnitude higher than for compounds with chiral carbon atoms. Despite the sizeable family of transition metal complexes with helicene-type ligands, there are only a few examples of such complexes with lanthanide ions. In this mini-review, we describe the most recent developments in the field of lanthanide-based complexes with helicene-type ligands and summarize insights regarding the further exploration of this family of compounds towards multifunctional chiral lanthanide single molecule magnets (Ln-SMMs).
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Brzozowska M, Handzlik G, Kurpiewska K, Zychowicz M, Pinkowicz D. Pseudo-tetrahedral vs. pseudo-octahedral Er III single molecule magnets and the disruptive role of coordinated TEMPO radical. Inorg Chem Front 2021. [DOI: 10.1039/d1qi00262g] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Tetrahedral ErIII complexes are potential candidates for high-performance single molecule magnets (SMMs).
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Affiliation(s)
| | | | | | | | - Dawid Pinkowicz
- Jagiellonian University
- Faculty of Chemistry
- 30-387 Kraków
- Poland
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Lu F, Ding MM, Li JX, Wang BL, Zhang YQ. Why lanthanide ErIII SIMs cannot possess huge energy barriers: a theoretical investigation. Dalton Trans 2020; 49:14576-14583. [DOI: 10.1039/d0dt02868a] [Citation(s) in RCA: 30] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
It is difficult for ErIII-based SIMs to possess energy barriers as high as DyIII through enhancing the surrounding equatorially coordinated ligand field.
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Affiliation(s)
- Fang Lu
- Jiangsu Key Lab for NSLSCS
- School of Physical Science and Technology
- Nanjing Normal University
- Nanjing 210023
- P. R. China
| | - Man-Man Ding
- Jiangsu Key Lab for NSLSCS
- School of Physical Science and Technology
- Nanjing Normal University
- Nanjing 210023
- P. R. China
| | - Jia-Xin Li
- Jiangsu Key Lab for NSLSCS
- School of Physical Science and Technology
- Nanjing Normal University
- Nanjing 210023
- P. R. China
| | - Bao-Lin Wang
- Jiangsu Key Lab for NSLSCS
- School of Physical Science and Technology
- Nanjing Normal University
- Nanjing 210023
- P. R. China
| | - Yi-Quan Zhang
- Jiangsu Key Lab for NSLSCS
- School of Physical Science and Technology
- Nanjing Normal University
- Nanjing 210023
- P. R. China
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