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Ito S, Yoshitake T, Ishida T. Ferromagnetic 2p-2p and 4f-2p Couplings in a Macrocycle from Two Biradicals and Two Gadolinium(III) Ions. Molecules 2022; 27:molecules27154930. [PMID: 35956880 PMCID: PMC9370185 DOI: 10.3390/molecules27154930] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2022] [Revised: 07/28/2022] [Accepted: 07/29/2022] [Indexed: 11/25/2022] Open
Abstract
A new ground triplet biradical 2′,4′,6′-triisopropylbiphenyl-3,5-diyl bis(tert-butyl nitroxide) (iPr3BPBN) was prepared and characterized by means of room-temperature ESR spectroscopy displaying a zero-field splitting pattern together with a half-field signal. Complex formation with gadolinium(III) 1,1,1,5,5,5-hexafluoropentane-2,4-dionate (hfac) afforded a macrocycle [{Gd(hfac)3(μ-iPr3BPBN)}2]. As the X-ray crystallographic analysis clarified, the biradical serves as a bridging ligand, giving a 16-membered ring, where each nitroxide radical oxygen atom is directly bonded to a Gd3+ ion. The magnetic study revealed that the iPr3BPBN bridge behaved as a practically triplet biradical and that the Gd3+-radical magnetic coupling was weakly ferromagnetic. The exchange parameters were estimated as 2jrad-rad/kB > 300 K and 2JGd-rad/kB = 1.2 K in the H = −2J S1•S2 convention. The DFT calculation based on the atomic coordinates clarified the ground triplet nature in metal-free iPr3BPBN and the enhanced triplet character upon coordination. The calculation also suggests that ferromagnetic coupling would be favorable when the Gd-O-N-C(sp2) torsion comes around 100°. The present results are compatible with the proposed magneto-structure relationship on the nitroxide-Gd compounds.
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Affiliation(s)
| | | | - Takayuki Ishida
- Correspondence: ; Tel.: +81-42-443-5490; Fax: +81-42-443-5501
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2
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Ito S, Takano R, Hatanaka SI, Ishida T. Rare-Earth (RE = Y, Gd, Tb, Dy, Ho, and Er) Chains Bridged with a Triplet Biradical and Magnetic Hysteresis Recorded for RE = Tb. Inorg Chem 2022; 61:10619-10623. [PMID: 35775974 DOI: 10.1021/acs.inorgchem.2c01107] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Complex formation of 5-tert-butyl-1,3-phenylene bis(tert-butyl nitroxide) and rare-earth (RE) metal ions gave a linear chain where each nitroxide O atom is directly bonded to the RE ion. The bridge was proven to be a ground triplet molecule in the complexes. A hysteresis loop was recorded below 2.8 K as a single-chain magnet for the RE = Tb derivative.
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Affiliation(s)
- Saki Ito
- Department of Engineering Science, The University of Electro-Communications, Chofu, Tokyo 182-8585, Japan
| | - Rina Takano
- Department of Engineering Science, The University of Electro-Communications, Chofu, Tokyo 182-8585, Japan
| | - Shin-Ichi Hatanaka
- Department of Engineering Science, The University of Electro-Communications, Chofu, Tokyo 182-8585, Japan
| | - Takayuki Ishida
- Department of Engineering Science, The University of Electro-Communications, Chofu, Tokyo 182-8585, Japan
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3
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Răducă M, Martins DOTA, Spinu CA, Hillebrand M, Tuna F, Ionita G, Mădălan AM, Lecourt C, Sutter JP, Andruh M. A new nitronyl‐nitroxide ligand for designing binuclear LnIII complexes: syntheses, crystal structures, magnetic and EPR studies. Eur J Inorg Chem 2022. [DOI: 10.1002/ejic.202200128] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Affiliation(s)
- Mihai Răducă
- Universitatea din Bucuresti Inorganic chemistry ROMANIA
| | | | | | | | - Floriana Tuna
- University of Manchester Department of Chemistry and Photon Science Institute UNITED KINGDOM
| | - Gabriela Ionita
- Institute of Physical Chemistry Bucarest Spectroscopy ROMANIA
| | | | - Constance Lecourt
- Universite de Touluuse Laboratoire de Chimie de Coordination du CNRS FRANCE
| | - Jean-Pascal Sutter
- Universite de Toulouse Laboratoire de Chimie de Coordination du CNRS FRANCE
| | - Marius Andruh
- Fac. of Chem - Inorg. Chem Lab University of Bucharest Str. Dumbrava Rosie nr. 23 20464 Bucharest ROMANIA
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4
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[Tb4(OH)4]-Cuboid Complex Dianion Stabilized with Six Carboxylate Bridges and Four Diketonate Caps. CRYSTALS 2022. [DOI: 10.3390/cryst12030402] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
A cubane-like complex dianion [Tb4(OH)4(tfa)6(hfac)4]2− was synthesized, accompanied by two counter cations of [Ni(hfac)(2pyIN)2]+, where Htfa, Hhfac, and 2pyIN stand for trifluoroacetic acid, 1,1,1,5,5,5-hexafluoropentane-2,4-dione, and 4,4,5,5-tetramethyl-2-pyridylimidazolin-1-oxyl, respectively. In the complex anion, each Tb ion was capped with hfac, and each Tb···Tb diagonal was bridged with tfa, thus forming an approximate Td symmetry, though the whole molecular formula was crystallographically independent in an orthorhombic Pbca space group. The ionic charge was −2 in total. The magnetic study revealed that the complex ions were magnetically isolated from each other. Practically no 4f–4f superexchange interaction was operative, while the 2p–3d ferromagnetic coupling seemed to be appreciable, as anticipated from the proposed magnetostructural relationship.
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5
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Tanimoto R, Wada T, Okada K, Shiomi D, Sato K, Takui T, Suzuki S, Naota T, Kozaki M. A Molecule Having 13 Unpaired Electrons: Magnetic Property of a Gadolinium(III) Complex Coordinated with Six Nitronyl Nitroxide Radicals. Inorg Chem 2022; 61:3018-3023. [PMID: 35129334 DOI: 10.1021/acs.inorgchem.1c03764] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
A gadolinium(III) complex coordinated with six nitronyl nitroxide radicals showed intriguing temperature-dependent changes in magnetic susceptibilities. The gadolinium(III) ion in the complex is pseudo-eight-coordinated by three singlet-ground-state diradical anion species based on nitronyl nitroxide radicals. The magnetic susceptibility (χpT) of the gadolinium(III) complex at 298 K, whose value corresponded to that of a system with 13 unpaired electrons (seven-spin system), decreased upon a lowering of the temperature to 11 K but increased upon a further lowering of the temperature. Finally, the χpT value at 2 K was found to be higher than that at room temperature. The temperature-dependent magnetic behavior could be explained by a structural change in the diradical anion ligand due to its flexibility.
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Affiliation(s)
- Ryu Tanimoto
- Graduate School of Science, Osaka City University, Sumiyoshi-ku, Osaka, Osaka 558-8585, Japan
| | - Tomoyuki Wada
- Graduate School of Science, Osaka City University, Sumiyoshi-ku, Osaka, Osaka 558-8585, Japan
| | - Keiji Okada
- Graduate School of Science, Osaka City University, Sumiyoshi-ku, Osaka, Osaka 558-8585, Japan
| | - Daisuke Shiomi
- Graduate School of Science, Osaka City University, Sumiyoshi-ku, Osaka, Osaka 558-8585, Japan
| | - Kazunobu Sato
- Graduate School of Science, Osaka City University, Sumiyoshi-ku, Osaka, Osaka 558-8585, Japan
| | - Takeji Takui
- Graduate School of Science, Osaka City University, Sumiyoshi-ku, Osaka, Osaka 558-8585, Japan
| | - Shuichi Suzuki
- Department of Chemistry, Graduate School of Engineering Science, Osaka University, Toyonaka, Osaka, Osaka 560-8531, Japan
| | - Takeshi Naota
- Department of Chemistry, Graduate School of Engineering Science, Osaka University, Toyonaka, Osaka, Osaka 560-8531, Japan
| | - Masatoshi Kozaki
- Graduate School of Science, Osaka City University, Sumiyoshi-ku, Osaka, Osaka 558-8585, Japan
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Kanetomo T, Naoi Y, Enomoto M. Gadolinium‐Triradical Complex with Ground
S
= 10 State: Synthesis, Structural Characterization and Magnetic Studies. Eur J Inorg Chem 2021. [DOI: 10.1002/ejic.202001113] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Affiliation(s)
- Takuya Kanetomo
- Department of Chemistry, Faculty of Science Division 1 Tokyo University of Science 1–3 Kagurazaka, Shinjuku-ku Tokyo 162-8601 Japan
| | - Yuya Naoi
- Department of Chemistry, Faculty of Science Division 1 Tokyo University of Science 1–3 Kagurazaka, Shinjuku-ku Tokyo 162-8601 Japan
| | - Masaya Enomoto
- Department of Chemistry, Faculty of Science Division 1 Tokyo University of Science 1–3 Kagurazaka, Shinjuku-ku Tokyo 162-8601 Japan
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Lu J, Jing P, Jin C, Xie J, Li L. Modulating the magnetization dynamics in Ln-Cu-Rad hetero-tri-spin complexes through cis/ trans coordination of nitronyl nitroxide radicals around the metal center. Dalton Trans 2021; 50:3280-3288. [PMID: 33587736 DOI: 10.1039/d1dt00090j] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
Self-assembling the novel nitronyl nitroxide radical NIT-3Py-5-Ph (2-(5-phenyl-3-pyridyl)-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide) with Ln(hfac)3·2H2O and Cu(hfac)2 (hfac = hexafluoroacetylacetonate) resulted in two heterometallic complexes with formula [LnCu(hfac)5(NIT-3Py-5-Ph)2] (Ln = Gd 1, Dy 2), in which two NIT-3Py-5-Ph radicals are coordinated with the LnIII ion via their nitroxide units in the cis-arrangement manner and the CuII ion is ligated by the pyridyl N donors of the radicals. Interestingly, when the phenyl group of NIT-3Py-5-Ph was replaced with a p-pyridyl group, a new family of 2D networks, namely, {[Ln(hfac)3][Cu(hfac)2]2(NIT-3Py-5-4Py)2}n (Ln = Gd 3, Tb 4, Dy 5; NIT-3Py-5-4Py = 2-(5-(4-pyridyl)-3-pyridyl)-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide) was obtained. In the 2D sheet, each NIT-3Py-5-4Py ligand serves as a μ3-bridge to bind one LnIII center by the aminoxyl moiety and two CuII ions through two pyridine groups to form a 2D structure. The LnIII ion is coordinated by two NO units of two radicals in a trans configuration. DC magnetic measurements indicate that ferromagnetic LnIII-NO exchange occurs in 1-5. AC studies reveal that 2 displays slow relaxation of the magnetization while no such magnetic relaxation is found in complex 5. The observed different magnetic relaxation behaviors of two Dy analogues could be attributed to the different coordination modes of NO groups of the radicals, and the coordination geometry of the Dy center is from C2v in 2 to D2d in 5.
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Affiliation(s)
- Jiao Lu
- Department of Chemistry, Key Laboratory of Advanced Energy Materials Chemistry, College of Chemistry, Nankai University, Tianjin 300071, China.
| | - Pei Jing
- Department of Chemistry, Key Laboratory of Advanced Energy Materials Chemistry, College of Chemistry, Nankai University, Tianjin 300071, China.
| | - Chaoyi Jin
- Department of Chemistry, Key Laboratory of Advanced Energy Materials Chemistry, College of Chemistry, Nankai University, Tianjin 300071, China.
| | - Junfang Xie
- Department of Chemistry, Key Laboratory of Advanced Energy Materials Chemistry, College of Chemistry, Nankai University, Tianjin 300071, China.
| | - Licun Li
- Department of Chemistry, Key Laboratory of Advanced Energy Materials Chemistry, College of Chemistry, Nankai University, Tianjin 300071, China.
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8
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Molecular S = 2 High-Spin, S = 0 Low-Spin and S = 0 ⇄ 2 Spin-Transition/-Crossover Nickel(II)-Bis(nitroxide) Coordination Compounds. INORGANICS 2021. [DOI: 10.3390/inorganics9020010] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
Heterospin systems have a great advantage in frontier orbital engineering since they utilize a wide diversity of paramagnetic chromophores and almost infinite combinations and mutual geometries. Strong exchange couplings are expected in 3d–2p heterospin compounds, where the nitroxide (aminoxyl) oxygen atom has a direct coordination bond with a nickel(II) ion. Complex formation of nickel(II) salts and tert-butyl 2-pyridyl nitroxides afforded a discrete 2p–3d–2p triad. Ferromagnetic coupling is favored when the magnetic orbitals, nickel(II) dσ and radical π*, are arranged in a strictly orthogonal fashion, namely, a planar coordination structure is characterized. In contrast, a severe twist around the coordination bond gives an orbital overlap, resulting in antiferromagnetic coupling. Non-chelatable nitroxide ligands are available for highly twisted and practically diamagnetic complexes. Here, the Ni–O–N–Csp2 torsion (dihedral) angle is supposed to be a useful metric to describe the nickel ion dislocated out of the radical π* nodal plane. Spin-transition complexes exhibited a planar coordination structure in a high-temperature phase and a nonplanar structure in a low-temperature phase. The gradual spin transition is described as a spin equilibrium obeying the van’t Hoff law. Density functional theory calculation indicates that the energy level crossing of the high- and low-spin states. The optimized structures of diamagnetic and high-spin states well agreed with the experimental large and small torsions, respectively. The novel mechanism of the present spin transition lies in the ferro-/antiferromagnetic coupling switch. The entropy-driven mechanism is plausible after combining the results of the related copper(II)-nitroxide compounds. Attention must be paid to the coupling parameter J as a variable of temperature in the magnetic analysis of such spin-transition materials. For future work, the exchange coupling may be tuned by chemical modification and external stimulus, because it has been clarified that the parameter is sensitive to the coordination structure and actually varies from 2J/kB = +400 K to −1400 K.
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9
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Nakamura T, Kanetomo T, Ishida T. Strong Antiferromagnetic Interaction in a Gadolinium(III) Complex with Methoxy-TEMPO Radical: A Relation between the Coupling and the Gd-O-N Angle. Inorg Chem 2021; 60:535-539. [PMID: 33382248 DOI: 10.1021/acs.inorgchem.0c02568] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
A new compound [Gd(hfac)3(MeOTEMPO)(MeOH)] (MeOTEMPO = 4-methoxy-2,2,6,6-tetramethylpiperidin-1-oxyl) was prepared. From the X-ray crystal structure analysis, the Gd-O-N angle is 170.9(3)°. The magnetic study clarified the Gd3+-radical interaction with 2J/kB = -26.6(3) K (in the H = -2JS1·S2 convention), which corresponds to one of the strongest antiferromagnetic couplings in the Gd-nitroxide systems. Wider Gd-O-N angles seem to favor stronger antiferromagnetic couplings.
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Affiliation(s)
- Takeshi Nakamura
- Department of Engineering Science, The University of Electro-Communications, Chofu, Tokyo 182-8585, Japan
| | - Takuya Kanetomo
- Department of Chemistry, Tokyo University of Science, Kagurazaka, Shinjuku-ku, Tokyo 162-8601, Japan
| | - Takayuki Ishida
- Department of Engineering Science, The University of Electro-Communications, Chofu, Tokyo 182-8585, Japan
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10
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Vaz MG, Andruh M. Molecule-based magnetic materials constructed from paramagnetic organic ligands and two different metal ions. Coord Chem Rev 2021. [DOI: 10.1016/j.ccr.2020.213611] [Citation(s) in RCA: 29] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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11
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Gould CA, Mu E, Vieru V, Darago LE, Chakarawet K, Gonzalez MI, Demir S, Long JR. Substituent Effects on Exchange Coupling and Magnetic Relaxation in 2,2′-Bipyrimidine Radical-Bridged Dilanthanide Complexes. J Am Chem Soc 2020; 142:21197-21209. [DOI: 10.1021/jacs.0c10612] [Citation(s) in RCA: 37] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Affiliation(s)
| | | | - Veacheslav Vieru
- Theory of Nanomaterials Group, Katholieke Universiteit Leuven, Celestijnenlaan 200F, 3001 Leuven, Belgium
| | | | | | | | - Selvan Demir
- Department of Chemistry, Michigan State University, East Lansing, Michigan 48824, United States
| | - Jeffrey R. Long
- Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States
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12
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Perfetti M, Caneschi A, Sukhikh TS, Vostrikova KE. Lanthanide Complexes with a Tripodal Nitroxyl Radical Showing Strong Magnetic Coupling. Inorg Chem 2020; 59:16591-16598. [PMID: 33119277 DOI: 10.1021/acs.inorgchem.0c02477] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
A series of isomorphous mononuclear complexes of Ln(III) ions comprising one stable tripodal oxazolidine nitroxyl radical were obtained in acetonitrile media starting from nitrates. The compounds, [LnRad(NO3)3] (Ln = Gd, Tb, Dy, Tm, Y; Rad = 4,4-dimethyl-2,2-bis(pyridin-2-yl)-1,3-oxazolidine-3-oxyl), have a molecular structure. Their coordination polyhedron, LnO7N2, can be described as a tricapped trigonal prism with symmetry not far from D3h. The extracted value of 23 cm-1 for the antiferromagnetic coupling of Gd-Rad established from the DC magnetic and EPR data is a record strength for the complexes of 4f elements with nitroxyl radicals. The terbium derivative displays frequency-dependent out-of-phase signals in zero field, indicating single-molecule magnetic behavior. With an applied field of 0.1 T, an effective barrier of 57 cm-1 is found.
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Affiliation(s)
- Mauro Perfetti
- Department of Chemistry U. Schiff, University of Florence and INSTM Reseach Unit, Via della Lastruccia 3-13, Sesto Fiorentino, 50019 Firenze, Italy
| | - Andrea Caneschi
- Dipartimento di Ingegneria Industriale - DIEF, Università degli Studi di Firenze, INSTM Research Unit of Firenze, Via di Santa Marta n. 3, 50139 Firenze, Italy
| | - Taisiya S Sukhikh
- Nikolaev Institute of Inorganic Chemistry, Siberian Branch, Russian Academy of Sciences, 630090 Novosibirsk, Russia
| | - Kira E Vostrikova
- Nikolaev Institute of Inorganic Chemistry, Siberian Branch, Russian Academy of Sciences, 630090 Novosibirsk, Russia
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Kyoden Y, Ishida T. A Hidden Coordination-Bond Torsional Deformation as a Sign of Possible Spin Transition in Nickel(II)-Bis(nitroxide) Compounds. Molecules 2020; 25:E3790. [PMID: 32825395 PMCID: PMC7503645 DOI: 10.3390/molecules25173790] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2020] [Revised: 08/13/2020] [Accepted: 08/18/2020] [Indexed: 11/17/2022] Open
Abstract
Complex formation of nickel(II) tetrafluoroborate and tert-butyl 5-phenyl-2-pyridyl nitroxide (phpyNO) in the presence of sodium cyanate gave a discrete molecule [Ni(phpyNO)2(X)2] (X = NCO). The Ni-O-N-Csp2 torsion angles were reduced on heating; 33.5(5)° and 36.2(4)° at 100 K vs. 25.7(10)° and 32.3(11)° at 400 K. The magnetic behavior was almost diamagnetic below ca. 100 K, and the χmT value reached 1.04 cm3 K mol-1 at 400 K. An analysis using the van't Hoff equation indicates a possible spin transition at T1/2 >> 400 K. Density functional theory calculation shows that the singlet-quintet energy gap decreases as the structural change from 100 to 400 K. The geometry optimization results suggest that the diamagnetic state has the Ni-O-N-Csp2 torsion angles of 32.7° while the Stotal = 2 state has those of 11.9°. The latter could not be experimentally observed even at 400 K. After overviewing the results on the known X = Br, Cl, and NCS derivatives, the magnetic behavior is described in a common phase diagram. The Br and Cl compounds undergo the energy level crossing of the high-/low-spin states, but the NCS and NCO compounds do not in a conventional experimental temperature range. The spin transition mechanism in this series involves the exchange coupling switch between ferro- and antiferromagnetic interactions, corresponding to the high- and low-spin phases, respectively.
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Affiliation(s)
| | - Takayuki Ishida
- Department of Engineering Science, The University of Electro-Communications, Chofu, Tokyo 182-8585, Japan;
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14
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Kyoden Y, Ishida T. An indication of spin-transition accompanied by an order-disorder structural transformation in [Ni(phpyNO)2(NCS)2] (phpyNO = tert-butyl 5-phenyl-2-pyridyl nitroxide). RSC Adv 2020; 10:16009-16015. [PMID: 35493632 PMCID: PMC9052934 DOI: 10.1039/d0ra02041a] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2020] [Accepted: 04/03/2020] [Indexed: 11/29/2022] Open
Abstract
Reaction of nickel(ii) thiocyanate and tert-butyl 5-phenyl-2-pyridyl nitroxide (phpyNO) afforded a 2p–3d–2p heterospin triad [Ni(phpyNO)2(NCS)2]. The compound crystallizes in the orthorhombic Pbcn space group. The whole molecule is crystallographically independent. The torsion angles around Ni–O–N–C2py are 26.8(4) and 27.3(4)° at 400 K, indicating appreciable orbital overlaps of the radical π* and nickel(ii) 3dx2−y2/3dz2 orbitals. In a low-temperature region, the torsion was enhanced, and the space group changed to monoclinic P21/c with a doubled asymmetric unit volume. The χmT value was practically null below ca. 140 K and, on heating to 400 K, gradually increased and reached 1.30 cm3 K mol−1. A van't Hoff analysis suggests a spin transition at T1/2 = 530(20) K. Density functional theory calculation reproduced ground Stotal = 0 with singlet-triplet gaps of 910 and 1263 K for the 140 K structure, and the gap was reduced to 297 K at 400 K. Consequently, the present compound can be considered as an incomplete spin-crossover material, as a result of T1/2 located above the experimental temperature window. The exchange coupling in [Ni(phpyNO)2(NCS)2] is strongly antiferromagnetic in a low-temperature structure whilst moderately antiferromagnetic in a high-temperature structure.![]()
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Affiliation(s)
- Yukiya Kyoden
- Department of Engineering Science
- The University of Electro-Communications
- Chofu
- Japan
| | - Takayuki Ishida
- Department of Engineering Science
- The University of Electro-Communications
- Chofu
- Japan
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15
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Liu F, Spree L, Krylov DS, Velkos G, Avdoshenko SM, Popov AA. Single-Electron Lanthanide-Lanthanide Bonds Inside Fullerenes toward Robust Redox-Active Molecular Magnets. Acc Chem Res 2019; 52:2981-2993. [PMID: 31571482 PMCID: PMC6796827 DOI: 10.1021/acs.accounts.9b00373] [Citation(s) in RCA: 84] [Impact Index Per Article: 16.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
A characteristic phenomenon of lanthanide-fullerene interactions is the transfer of metal valence electrons to the carbon cage. With early lanthanides such as La, a complete transfer of six valence electrons takes place for the metal dimers encapsulated in the fullerene cage. However, the low energy of the σ-type Ln-Ln bonding orbital in the second half of the lanthanide row limits the Ln2 → fullerene transfer to only five electrons. One electron remains in the Ln-Ln bonding orbital, whereas the fullerene cage with a formal charge of -5 is left electron-deficient. Such Ln2@C80 molecules are unstable in the neutral form but can be stabilized by substitution of one carbon atom by nitrogen to give azafullerenes Ln2@C79N or by quenching the unpaired electron on the fullerene cage by reacting it with a chemical such as benzyl bromide, transforming one sp2 carbon into an sp3 carbon and yielding the monoadduct Ln2@C80(CH2Ph). Because of the presence of the Ln-Ln bonding molecular orbital with one electron, the Ln2@C79N and Ln2@C80(R) molecules feature a unique single-electron Ln-Ln bond and an unconventional +2.5 oxidation state of the lanthanides. In this Account, which brings together metallofullerenes, molecular magnets, and lanthanides in unconventional valence states, we review the progress in the studies of dimetallofullerenes with single-electron Ln-Ln bonds and highlight the consequences of the unpaired electron residing in the Ln-Ln bonding orbital for the magnetic interactions between Ln ions. Usually, Ln···Ln exchange coupling in polynuclear lanthanide compounds is weak because of the core nature of 4f electrons. However, when interactions between Ln centers are mediated by a radical bridge, stronger coupling may be achieved because of the diffuse nature of radical-based orbitals. Ultimately, when the role of a radical bridge is played by a single unpaired electron in the Ln-Ln bonding orbital, the strength of the exchange coupling is increased dramatically. Giant exchange coupling in endohedral Ln2 dimers is combined with a rather strong axial ligand field exerted on the lanthanide ions by the fullerene cage and the excess electron density localized between two Ln ions. As a result, Ln2@C79N and Ln2@C80(CH2Ph) compounds exhibit slow relaxation of magnetization and exceptionally high blocking temperatures for Ln = Dy and Tb. At low temperatures, the [Ln3+-e-Ln3+] fragment behaves as a single giant spin. Furthermore, the Ln-Ln bonding orbital in dimetallofullerenes is redox-active, which allows its population to be changed by electrochemical reactions, thus changing the magnetic properties because the change in the number of electrons residing in the Ln-Ln orbital affects the magnetic structure of the molecule.
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Affiliation(s)
- Fupin Liu
- Leibniz Institute for Solid State and Materials Research (IFW Dresden), Helmholtzstraße 20, 01069 Dresden, Germany
| | - Lukas Spree
- Leibniz Institute for Solid State and Materials Research (IFW Dresden), Helmholtzstraße 20, 01069 Dresden, Germany
| | - Denis S. Krylov
- Leibniz Institute for Solid State and Materials Research (IFW Dresden), Helmholtzstraße 20, 01069 Dresden, Germany
- Center for Quantum Nanoscience, Institute for Basic Science (IBS), Ewha Womans University, Seoul 03760, Republic of Korea
| | - Georgios Velkos
- Leibniz Institute for Solid State and Materials Research (IFW Dresden), Helmholtzstraße 20, 01069 Dresden, Germany
| | - Stanislav M. Avdoshenko
- Leibniz Institute for Solid State and Materials Research (IFW Dresden), Helmholtzstraße 20, 01069 Dresden, Germany
| | - Alexey A. Popov
- Leibniz Institute for Solid State and Materials Research (IFW Dresden), Helmholtzstraße 20, 01069 Dresden, Germany
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16
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Kyoden Y, Homma Y, Ishida T. High-Spin and Incomplete Spin-Crossover Polymorphs in Doubly Chelated [Ni(L) 2Br 2] (L = tert-Butyl 5-Phenyl-2-pyridyl Nitroxide). Inorg Chem 2019; 58:10743-10755. [PMID: 31368687 DOI: 10.1021/acs.inorgchem.9b00885] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Complexation of nickel(II) bromide with tert-butyl 5-phenyl-2-pyridyl nitroxide (phpyNO) gave two morphs of doubly chelated [Ni(phpyNO)2Br2] as a 2p-3d-2p heterospin triad. The α phase crystallizes in the orthorhombic space group Pbcn. An asymmetric unit involves a half-molecule. The torsion angle around Ni-O-N-C2py is as small as 6.5(3)° at 100 K and 7.0(6)° at 400 K, guaranteeing an orthogonal arrangement between the magnetic radical π* and metal 3dx2-y2 and 3dz2 orbitals. Magnetic study revealed the high-spin ground state with the exchange coupling constant 2J/kB = +288(5) K, on the basis of a symmetrical spin Hamiltonian. The β phase crystallizes in the monoclinic space group P21/n. The whole molecule is an independent unit. The Ni-O-N-C2py torsion angles are 24.2(6) and 37.2(5)° at 100 K and 10.4(7) and 25.9(6)° at 400 K. A magnetic study revealed a very gradual and nonhysteretic spin transition. An analysis based on the van't Hoff equation gave a successful fit with the spin-crossover temperature of 134(1) K, although the susceptibility did not reach the theoretical high-spin value at 400 K. Density functional theory calculation on the β phase showed ground Stotal = 0 in the low-temperature structure while Stotal = 2 in the high-temperature structure, supporting the synchronized exchange coupling switch on both sides. Consequently, the β phase can be recognized as an "incomplete spin crossover" material, as a result of conflicting thermal depopulation effects in a high-temperature region.
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Affiliation(s)
- Yukiya Kyoden
- Department of Engineering Science , The University of Electro-Communications , Chofu, Tokyo 182-8585 , Japan
| | - Yuta Homma
- Department of Engineering Science , The University of Electro-Communications , Chofu, Tokyo 182-8585 , Japan
| | - Takayuki Ishida
- Department of Engineering Science , The University of Electro-Communications , Chofu, Tokyo 182-8585 , Japan
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17
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Kashiro A, Kyoden Y, Okazawa A, Ishida T. Moving Organic Molecules in Crystalline Solids: Gradual Structural Transition and Spin Transition/Crossover. J SYN ORG CHEM JPN 2019. [DOI: 10.5059/yukigoseikyokaishi.77.684] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Affiliation(s)
| | | | | | - Takayuki Ishida
- Department of Engineering Science, The University of Electro-Communications
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18
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Cole BE, Cheisson T, Higgins RF, Nakamaru-Ogiso E, Manor BC, Carroll PJ, Schelter EJ. Redox-Driven Chelation and Kinetic Separation of Select Rare Earths Using a Tripodal Nitroxide Proligand. Inorg Chem 2019; 59:172-178. [DOI: 10.1021/acs.inorgchem.9b00975] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Affiliation(s)
- Bren E. Cole
- P. Roy and Diana T. Vagelos Laboratories, Department of Chemistry, University of Pennsylvania, 231 South 34th Street, Philadelphia, Pennsylvania 19104, United States
| | - Thibault Cheisson
- P. Roy and Diana T. Vagelos Laboratories, Department of Chemistry, University of Pennsylvania, 231 South 34th Street, Philadelphia, Pennsylvania 19104, United States
| | - Robert F. Higgins
- P. Roy and Diana T. Vagelos Laboratories, Department of Chemistry, University of Pennsylvania, 231 South 34th Street, Philadelphia, Pennsylvania 19104, United States
| | - Eiko Nakamaru-Ogiso
- Department of Biochemistry and Biophysics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania 19104, United States
| | - Brian C. Manor
- P. Roy and Diana T. Vagelos Laboratories, Department of Chemistry, University of Pennsylvania, 231 South 34th Street, Philadelphia, Pennsylvania 19104, United States
| | - Patrick J. Carroll
- P. Roy and Diana T. Vagelos Laboratories, Department of Chemistry, University of Pennsylvania, 231 South 34th Street, Philadelphia, Pennsylvania 19104, United States
| | - Eric J. Schelter
- P. Roy and Diana T. Vagelos Laboratories, Department of Chemistry, University of Pennsylvania, 231 South 34th Street, Philadelphia, Pennsylvania 19104, United States
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19
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Kanetomo T, Ichihashi K, Enomoto M, Ishida T. Ground Triplet Spirobiradical: 2,2',7,7'-Tetra( tert-butyl)-9,9'(10 H,10' H)-spirobiacridine-10,10'-dioxyl. Org Lett 2019; 21:3909-3912. [PMID: 30973232 DOI: 10.1021/acs.orglett.9b00901] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
A new spirobiradical, 2,2',7,7'-tetra( tert-butyl)-9,9'(10 H,10' H)-spirobiacridine-10,10'-dioxyl, was prepared. The crystallographic analysis clarified the D2 d molecular structure, suggesting the degeneracy of SOMOs. The magnetic study revealed that intramolecular ferromagnetic coupling was operative with 2 J/ kB = +23(1) K. To the best of our knowledge, the ferromagnetic coupling parameter is the largest ever reported for a paramagnetic spiro compound.
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Affiliation(s)
- Takuya Kanetomo
- Tokyo University of Science , 1-3 Kagurazaka , Shinjuku-ku, Tokyo 162-8601 , Japan
| | - Kana Ichihashi
- The University of Electro-Communications , 1-5-1 Chofugaoka , Chofu, Tokyo 182-8585 , Japan
| | - Masaya Enomoto
- Tokyo University of Science , 1-3 Kagurazaka , Shinjuku-ku, Tokyo 162-8601 , Japan
| | - Takayuki Ishida
- The University of Electro-Communications , 1-5-1 Chofugaoka , Chofu, Tokyo 182-8585 , Japan
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20
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Nasani R, Sidharth TNS, Roy S, Mondal A, Rawson JM, Konar S. Probing through-space and through-bond magnetic exchange couplings in a new benzotriazinyl radical and its metal complexes. Dalton Trans 2019; 48:14189-14200. [DOI: 10.1039/c9dt01918a] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
A new Blatter radical and its Zn(ii) (1), Ni(ii) (2) and Co(ii) (3) complexes were isolated. Complex 1 exhibited radical⋯radical antiferromagnetic exchange coupling, whereas complexes 2 and 3 showed ferromagnetic metal–radical coupling.
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Affiliation(s)
- Rajendar Nasani
- Department of Chemistry
- Indian Institute of Science Education and Research Bhopal
- Bhopal 462 066
- India
| | | | - Subhadip Roy
- Department of Chemistry
- Indian Institute of Science Education and Research Bhopal
- Bhopal 462 066
- India
| | - Arpan Mondal
- Department of Chemistry
- Indian Institute of Science Education and Research Bhopal
- Bhopal 462 066
- India
| | - Jeremy M. Rawson
- Department of Chemistry & Biochemistry
- The University of Windsor
- Windsor
- CANADA
| | - Sanjit Konar
- Department of Chemistry
- Indian Institute of Science Education and Research Bhopal
- Bhopal 462 066
- India
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21
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Huang G, Daiguebonne C, Calvez G, Suffren Y, Guillou O, Guizouarn T, Le Guennic B, Cador O, Bernot K. Strong Magnetic Coupling and Single-Molecule-Magnet Behavior in Lanthanide-TEMPO Radical Chains. Inorg Chem 2018; 57:11044-11057. [DOI: 10.1021/acs.inorgchem.8b01640] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Gang Huang
- Univ Rennes, INSA Rennes, CNRS, ISCR (Institut des Sciences Chimiques de Rennes) –UMR 6226, F-35000 Rennes, France
| | - Carole Daiguebonne
- Univ Rennes, INSA Rennes, CNRS, ISCR (Institut des Sciences Chimiques de Rennes) –UMR 6226, F-35000 Rennes, France
| | - Guillaume Calvez
- Univ Rennes, INSA Rennes, CNRS, ISCR (Institut des Sciences Chimiques de Rennes) –UMR 6226, F-35000 Rennes, France
| | - Yan Suffren
- Univ Rennes, INSA Rennes, CNRS, ISCR (Institut des Sciences Chimiques de Rennes) –UMR 6226, F-35000 Rennes, France
| | - Olivier Guillou
- Univ Rennes, INSA Rennes, CNRS, ISCR (Institut des Sciences Chimiques de Rennes) –UMR 6226, F-35000 Rennes, France
| | - Thierry Guizouarn
- Univ Rennes, INSA Rennes, CNRS, ISCR (Institut des Sciences Chimiques de Rennes) –UMR 6226, F-35000 Rennes, France
| | - Boris Le Guennic
- Univ Rennes, INSA Rennes, CNRS, ISCR (Institut des Sciences Chimiques de Rennes) –UMR 6226, F-35000 Rennes, France
| | - Olivier Cador
- Univ Rennes, INSA Rennes, CNRS, ISCR (Institut des Sciences Chimiques de Rennes) –UMR 6226, F-35000 Rennes, France
| | - Kevin Bernot
- Univ Rennes, INSA Rennes, CNRS, ISCR (Institut des Sciences Chimiques de Rennes) –UMR 6226, F-35000 Rennes, France
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22
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Two chain-based TbIII/DyIII complexes derived from m-nitrobenzoic acid with totally different structures and magnetic properties. J Mol Struct 2018. [DOI: 10.1016/j.molstruc.2018.03.112] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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23
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Guo J, Sun J, Sun G, Sun Z, Li L. Construction and Magnetic Study of One‐Dimensional Lanthanide–Radical Chains Involving Pyridinone‐Substituted Nitronyl Nitroxide Radicals. Eur J Inorg Chem 2018. [DOI: 10.1002/ejic.201800513] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Affiliation(s)
- Jianni Guo
- Department of Chemistry Key Laboratory of Advanced Energy Materials Chemistry and Tianjin Key Laboratory of Metal and Molecule‐based Material Chemistry College of Chemistry Nankai University 300071 Tianjin China
| | - Juan Sun
- Department of Chemistry Key Laboratory of Advanced Energy Materials Chemistry and Tianjin Key Laboratory of Metal and Molecule‐based Material Chemistry College of Chemistry Nankai University 300071 Tianjin China
| | - Guifang Sun
- Department of Chemistry Key Laboratory of Advanced Energy Materials Chemistry and Tianjin Key Laboratory of Metal and Molecule‐based Material Chemistry College of Chemistry Nankai University 300071 Tianjin China
| | - Zan Sun
- Department of Chemistry Key Laboratory of Advanced Energy Materials Chemistry and Tianjin Key Laboratory of Metal and Molecule‐based Material Chemistry College of Chemistry Nankai University 300071 Tianjin China
| | - Licun Li
- Department of Chemistry Key Laboratory of Advanced Energy Materials Chemistry and Tianjin Key Laboratory of Metal and Molecule‐based Material Chemistry College of Chemistry Nankai University 300071 Tianjin China
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24
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Velkos G, Krylov DS, Kirkpatrick K, Liu X, Spree L, Wolter AUB, Büchner B, Dorn HC, Popov AA. Giant exchange coupling and field-induced slow relaxation of magnetization in Gd 2@C 79N with a single-electron Gd-Gd bond. Chem Commun (Camb) 2018; 54:2902-2905. [PMID: 29497728 PMCID: PMC5885278 DOI: 10.1039/c8cc00112j] [Citation(s) in RCA: 30] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2018] [Accepted: 02/13/2018] [Indexed: 12/18/2022]
Abstract
Magnetic properties of the azafullerene Gd2@C79N are studied by SQUID magnetometry. The effective exchange coupling constant jGd,e between the Gd spins and the spin of unpaired electron residing on the single-electron Gd-Gd bond is determined to be 170 ± 10 cm-1. Low temperature AC measurements revealed field-induced millisecond-long relaxation of magnetization.
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Affiliation(s)
- G Velkos
- Leibniz Institute for Solid State and Materials Research, Dresden 01069, Germany.
| | - D S Krylov
- Leibniz Institute for Solid State and Materials Research, Dresden 01069, Germany.
| | - K Kirkpatrick
- Department of Chemistry, Virginia Polytechnic Institute and State University, Blacksburg, Virginia 24061, USA
| | - X Liu
- Department of Chemistry, Virginia Polytechnic Institute and State University, Blacksburg, Virginia 24061, USA
| | - L Spree
- Leibniz Institute for Solid State and Materials Research, Dresden 01069, Germany.
| | - A U B Wolter
- Leibniz Institute for Solid State and Materials Research, Dresden 01069, Germany.
| | - B Büchner
- Leibniz Institute for Solid State and Materials Research, Dresden 01069, Germany.
| | - H C Dorn
- Department of Chemistry, Virginia Polytechnic Institute and State University, Blacksburg, Virginia 24061, USA and Virginia Tech Carilion Research Institute, Roanoke, Virginia 24016, USA.
| | - A A Popov
- Leibniz Institute for Solid State and Materials Research, Dresden 01069, Germany.
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25
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Horii Y, Kishiue S, Damjanović M, Katoh K, Breedlove BK, Enders M, Yamashita M. Supramolecular Approach for Enhancing Single-Molecule Magnet Properties of Terbium(III)-Phthalocyaninato Double-Decker Complexes with Crown Moieties. Chemistry 2018; 24:4320-4327. [PMID: 29265595 DOI: 10.1002/chem.201705378] [Citation(s) in RCA: 31] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2017] [Indexed: 11/10/2022]
Abstract
A TbIII -phthalocyaninato double-decker ([1]0 ) single-molecule magnet (SMM) having four 15-crown-5 moieties in one of the ligands was synthesized, and its dimerization and magnetic properties were studied in an attempt to utilize the supramolecular aggregation for enhancing the SMM properties. Aggregation of [1]0 to form [12 K4 ]4+ in the presence of K+ ions was studied by using UV/Vis-NIR absorption and NMR spectroscopies. For the magnetic measurements, [1]0 and [12 K4 ]4+ were dispersed in poly(methyl methacrylate) (PMMA). UV/Vis-NIR absorption measurements on the PMMA dispersed samples were used to track the formation of [12 K4 ]4+ . Direct current (DC) magnetic susceptibility measurements revealed that there were ferromagnetic Tb-Tb interactions in [12 K4 ]4+ , whereas there was no indication of ferromagnetic interactions in [1]0 . Upon the formation of [12 K4 ]4+ from [1]0 and K+ ions, the temperature at which the magnetic hysteresis occurred increased from 7 to 15 K. In addition, the area of magnetic hysteresis became larger for [12 K4 ]4+ , meaning that SMM properties of [12 K4 ]4+ are superior to those of [1]0 . Alternating current (AC) magnetic measurements were used to confirm this observation. Magnetic relaxation times at 2 K increased 1000-fold upon dimerization of [1]0 to [12 K4 ]4+ , demonstrating the effectiveness of using K+ ions to induce dimer formation for the improvement of the SMM properties.
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Affiliation(s)
- Yoji Horii
- Department of Chemistry, Graduate School of Science, Tohoku University, 6-3, Aramaki-Aza-Aoba, Aoba-ku, Sendai, 980-8578, Japan
| | - Shuhei Kishiue
- Department of Chemistry, Graduate School of Science, Tohoku University, 6-3, Aramaki-Aza-Aoba, Aoba-ku, Sendai, 980-8578, Japan
| | - Marko Damjanović
- Physikalisches Institut and Institute of Nanotechnology, Karlsruhe Institute of Technology, Wolfgang-Gaede-Strasse 1, Karlsruhe, 76131, Germany.,Institute of Inorganic Chemistry, Heidelberg University, Im Neuenheimer Feld 270, 69120, Heidelberg, Germany
| | - Keiichi Katoh
- Department of Chemistry, Graduate School of Science, Tohoku University, 6-3, Aramaki-Aza-Aoba, Aoba-ku, Sendai, 980-8578, Japan
| | - Brian K Breedlove
- Department of Chemistry, Graduate School of Science, Tohoku University, 6-3, Aramaki-Aza-Aoba, Aoba-ku, Sendai, 980-8578, Japan
| | - Markus Enders
- Institute of Inorganic Chemistry, Heidelberg University, Im Neuenheimer Feld 270, 69120, Heidelberg, Germany
| | - Masahiro Yamashita
- Department of Chemistry, Graduate School of Science, Tohoku University, 6-3, Aramaki-Aza-Aoba, Aoba-ku, Sendai, 980-8578, Japan.,WPI Research Center, Advanced Institute for Materials Research, Tohoku University, 2-1-1 Katahira, Aoba-ku, Sendai, 980-8577, Japan.,School of Materials Science and Engineering, Nankai University, Tianjin, 300350, China
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26
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Sekine H, Ishida T. Unexpected Complexes of a [3+3] Cycloadduct from Biphenyl-3,5-diyl Bis( tert-butyl nitroxide) with Gadolinium(III) 1,1,1,5,5,5-Hexafluoropentane-2,4-dionate. CHEM LETT 2018. [DOI: 10.1246/cl.170933] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Affiliation(s)
- Hiroyasu Sekine
- Department of Engineering Science, The University of Electro-Communications, Chofu, Tokyo 182-8585, Japan
| | - Takayuki Ishida
- Department of Engineering Science, The University of Electro-Communications, Chofu, Tokyo 182-8585, Japan
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27
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28
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29
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Kanetomo T, Kihara T, Miyake A, Matsuo A, Tokunaga M, Kindo K, Nojiri H, Ishida T. Giant Exchange Coupling Evidenced with a Magnetization Jump at 52 T for a Gadolinium-Nitroxide Chelate. Inorg Chem 2017; 56:3310-3314. [PMID: 28281348 DOI: 10.1021/acs.inorgchem.6b02685] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The Gd-radical complex [GdIII(hfac)3(6bpyNO)] (6bpyNO = 2,2'-bipyridin-6-yl tert-butyl nitroxide; Hhfac = 1,1,1,5,5,5-hexafluoropentane-2,4-dione) showed a magnetization jump at 52 T observed in a pulsed-field facility, corresponding to an exchange coupling constant of -17.4 K. Furthermore, hysteretic behavior due to a relatively slow magnetization reversal was recorded around 2 T. From the high-frequency EPR study, the exchange coupling between Gd and radical spins accompanies an anisotropic character, which is responsible for both the broad jump and the slow magnetization reversal.
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Affiliation(s)
- Takuya Kanetomo
- Department of Engineering Science, The University of Electro-Communications , Chofu, Tokyo 182-8585, Japan
| | - Takumi Kihara
- Institute for Materials Research, Tohoku University , Sendai, Miyagi 980-8577, Japan
| | - Atsushi Miyake
- Institute for Solid State Physics, The University of Tokyo , Kashiwa, Chiba 277-8581, Japan
| | - Akira Matsuo
- Institute for Solid State Physics, The University of Tokyo , Kashiwa, Chiba 277-8581, Japan
| | - Masashi Tokunaga
- Institute for Solid State Physics, The University of Tokyo , Kashiwa, Chiba 277-8581, Japan
| | - Koichi Kindo
- Institute for Solid State Physics, The University of Tokyo , Kashiwa, Chiba 277-8581, Japan
| | - Hiroyuki Nojiri
- Institute for Materials Research, Tohoku University , Sendai, Miyagi 980-8577, Japan
| | - Takayuki Ishida
- Department of Engineering Science, The University of Electro-Communications , Chofu, Tokyo 182-8585, Japan
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30
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Karbowiak M, Rudowicz C, Nakamura T, Murakami R, Ishida T. Spectroscopic and magnetic studies of erbium(III)-TEMPO complex as a potential single-molecule magnet: Interplay of the crystal-field and exchange coupling effects. Chem Phys Lett 2016. [DOI: 10.1016/j.cplett.2016.09.033] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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