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Yang EC, Tsai YT, Chang PY, Ozerov M, Krzystek J, Chien SY, He JX, Kuo TS, Sheu HS. Cobalt(II) Single-Ion Magnet Coordinated by Double Deprotonation of 2,2'-Bipyridine-6,6'-diol Ligands. ACS OMEGA 2024; 9:26149-26158. [PMID: 38911747 PMCID: PMC11190935 DOI: 10.1021/acsomega.4c01576] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/19/2024] [Revised: 05/22/2024] [Accepted: 05/27/2024] [Indexed: 06/25/2024]
Abstract
In this study, we synthesized a new Co(II) complex, [NMe4]2[Co(bpyO2)2] (1), using deprotonated 2,2'-bipyridine-6,6'-diol ligands (bpyO2 2-). This compound exhibits a significant zero-field splitting (D) value. The far-infrared magneto spectroscopy and high-frequency and field electron paramagnetic resonance (HFEPR) measurements indicated that compound 1 possesses D = -54.8 cm-1 and E ∼ 0 cm-1. These findings were subsequently confirmed by other experimental data, including DC magnetic susceptibilities and variable temperature and variable magnetic field reduced magnetizations. Additionally, we conducted a series of AC magnetic susceptibility measurements to investigate the kinetics of magnetization relaxation. Below 6.6 K and under zero external magnetic field, fast quantum tunneling of magnetization (QTM) dominates (∼570 Hz), and temperature-independent out-of-phase signals are observed. Above 8.1 K, temperature-dependent behavior is observed. Furthermore, we examined the AC magnetic susceptibility behavior under external magnetic fields ranging from 300 to 4000 G. The effect of QTM is significantly reduced in the presence of an external magnetic field. Temperature-dependent behavior is primarily governed by Raman relaxation. Through structural analysis of compound 1 and a series of pure nitrogen-coordinated single-ion magnets (SIMs), we propose that the oxo substituents from the double-deprotonated form of the 2,2'-bipyridine-6,6'-diol ligands donate their negative charge to the pyridine ring, forming amido anion sites. This triggers a more pronounced out-of-phase signal than that observed in pure pyridine-coordinated compounds. Moreover, we observed intermolecular interactions, including intermolecular hydrogen bonding, which, to some extent, influenced the slow relaxation of molecules. Therefore, we speculate that the slow relaxation phenomenon of compound 1 may be attributed to the combination of oxo back-donating effects and intermolecular interactions.
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Affiliation(s)
- En-Che Yang
- Department
of Chemistry, Fu-Jen Catholic University
Hsinchuang, New Taipei
City 242062, Taiwan, Republic of China
| | - Yu-Tung Tsai
- Department
of Chemistry, Fu-Jen Catholic University
Hsinchuang, New Taipei
City 242062, Taiwan, Republic of China
| | - Po-Ya Chang
- National
Synchrotron Radiation Research Center, Hsinchu 300092, Taiwan, Republic of China
| | - Mykhaylo Ozerov
- National
High Magnetic Field Laboratory, Florida
State University, Tallahassee, Florida 32310, United States
| | - Jurek Krzystek
- National
High Magnetic Field Laboratory, Florida
State University, Tallahassee, Florida 32310, United States
| | - Su-Ying Chien
- Instrumentation
Centre College of Science, National Taiwan
University, Taipei 10617, Taiwan,
Republic of China
| | - Jun-Xian He
- Department
of Chemistry, Fu-Jen Catholic University
Hsinchuang, New Taipei
City 242062, Taiwan, Republic of China
| | - Ting-Shen Kuo
- Centre
of National Taiwan Normal University, Taipei 11677, Taiwan, Republic of China
| | - Hwo-Shuenn Sheu
- National
Synchrotron Radiation Research Center, Hsinchu 300092, Taiwan, Republic of China
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2
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Juráková J, Šalitroš I. Co(II) single-ion magnets: synthesis, structure, and magnetic properties. MONATSHEFTE FUR CHEMIE 2022; 153:1001-1036. [PMID: 35615113 PMCID: PMC9123880 DOI: 10.1007/s00706-022-02920-0] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/31/2021] [Accepted: 04/25/2022] [Indexed: 01/01/2023]
Abstract
Magnetoactive coordination compounds exhibiting bi- or multistability between two or more magnetic stable states present an attractive example of molecular switches. Currently, the research is focused on molecular nanomagnets, especially single molecule magnets (SMMs), which are molecules, where the slow relaxation of the magnetization based on the purely molecular origin is observed. Contrary to ferromagnets, the magnetic bistability of SMMs does not require intermolecular interactions, which makes them particularly interesting in terms of application potential, especially in the high-density storage of data. This paper aims to introduce the readers into a basic understanding of SMM behaviour, and furthermore, it provides an overview of the attractive Co(II) SMMs with emphasis on the relation between structural features, magnetic anisotropy, and slow relaxation of magnetization in tetra-, penta-, and hexacoordinate complexes.
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Affiliation(s)
- Jana Juráková
- Central European Institute of Technology, Brno University of Technology, Purkyňova 123, 61200 Brno, Czech Republic
| | - Ivan Šalitroš
- Central European Institute of Technology, Brno University of Technology, Purkyňova 123, 61200 Brno, Czech Republic
- Department of Inorganic Chemistry, Faculty of Chemical and Food Technology, Slovak University of Technology in Bratislava, Bratislava, 81237 Slovakia
- Department of Inorganic Chemistry, Faculty of Science, Palacký University, 17. listopadu 12, 771 46, Olomouc, Czech Republic
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3
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Lv W, Cui HH, Chen L, Zhang YQ, Chen XT, Wang Z, Ouyang ZW, Xue ZL. Magnetic anisotropy of two tetrahedral Co(II)-halide complexes with triphenylphosphine ligands. Dalton Trans 2022; 51:7530-7538. [PMID: 35506535 DOI: 10.1039/d2dt00121g] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Recently, the choice of ligand and geometric control of mononuclear complexes, which can affect the relaxation pathways and blocking temperature, have received wide attention in the field of single-ion magnets (SIMs). To find out the influence of the coordination environment on SIMs, two four-coordinate mononuclear Co(II) complexes [NEt4][Co(PPh3)X3] (X = Cl-, 1; Br-, 2) have been synthesized and studied by X-ray single crystallography, magnetic measurements, high-frequency and -field EPR (HF-EPR) spectroscopy and theoretical calculations. Both complexes are in a cubic space group Pa3̄ (No. 205), containing a slightly distorted tetrahedral moiety with crystallographically imposed C3v symmetry through the [Co(PPh3)X3]- anion. The direct-current (dc) magnetic data and HF-EPR spectroscopy indicated the anisotropic S = 3/2 spin ground states of the Co(II) ions with the easy-plane anisotropy for 1 and 2. Ab initio calculations were performed to confirm the positive magnetic anisotropies of 1 and 2. Frequency- and temperature-dependent alternating-current (ac) magnetic susceptibility measurements revealed slow magnetic relaxation for 1 and 2 at an applied dc field. Finally, the magnetic properties of 1 and 2 were compared to those of other Co(II) complexes with a [CoAB3] moiety.
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Affiliation(s)
- Wei Lv
- State Key Laboratory of Coordination Chemistry, School of Chemistry and Chemical Engineering, Nanjing University, Nanjing 210023, China.
| | - Hui-Hui Cui
- State Key Laboratory of Coordination Chemistry, School of Chemistry and Chemical Engineering, Nanjing University, Nanjing 210023, China.
| | - Lei Chen
- School of Environmental and Chemical Engineering, Jiangsu University of Science and Technology, Zhenjiang 212003, China
| | - Yi-Quan Zhang
- Jiangsu Key Laboratory for NSLSCS, School of Physical Science and Technology, Nanjing Normal University, Nanjing 210023, China
| | - Xue-Tai Chen
- State Key Laboratory of Coordination Chemistry, School of Chemistry and Chemical Engineering, Nanjing University, Nanjing 210023, China.
| | - Zhenxing Wang
- Wuhan National High Magnetic Field Center & School of Physics, Huazhong University of Science and Technology, Wuhan 430074, China
| | - Zhong-Wen Ouyang
- Wuhan National High Magnetic Field Center & School of Physics, Huazhong University of Science and Technology, Wuhan 430074, China
| | - Zi-Ling Xue
- Department of Chemistry, University of Tennessee, Knoxville, Tennessee 37996, USA
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4
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Bhowmick I, Newell BS, Shores MP. A systematic study of the influence of ligand field on the slow magnetic dynamics of Co(ii)-diimine compounds. Dalton Trans 2021; 50:10737-10748. [PMID: 34269774 DOI: 10.1039/d0dt01597k] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Herein we report heteroleptic Co(ii) diimine complexes [Co(H2bip)2Cl2] (1), [Co(H2bip)2Br2] (2), [Co(H2bip)3]Br2·1MeOH (3) and [Co(H2bip)2(Me2bpy)]Br2·(MeCN)0.5·(H2O)0.25 (4) (H2bip = 2,2'-bi-1,4,5,6-tetrahydropyrimidine, bpy = 2,2'-dipyridyl, Me2bpy = 4,4'-Me-2,2'-dipyridyl), purposefully prepared to enable a systematic study of magnetic property changes arising from the increase of overall ligand field from σ/π-donor chlorido (1) to π-acceptor 4,4'Me-2,2'bpy (4). The presence of axial and rhombic anisotropy (D and E) of these compounds is sufficient to allow 1-4 to show field-induced slow relaxation of magnetization. Interestingly, we found as the effective ligand field is increased in the series, rhombicity (E/D) decreases, and the magnetic relaxation profile changes significantly, where relaxation of magnetization at a specific temperature becomes gradually faster. We performed mechanistic analyses of the temperature dependence of magnetic relaxation times considering Orbach relaxation processes, Raman-like relaxation and quantum tunnelling of magnetization (QTM). The effective energy barrier of the Orbach relaxation process (Ueff) is largest in compound 1 (19.2 cm-1) and gradually decreases in the order 1 > 2 > 3 > 4 giving a minimum value in compound 4 (8.3 cm-1), where the Raman-like mechanism showed the possibility of different types of phonon activity below and above ∼2.5 K. As a precursor of 1, the tetrahedral complex [Co(H2bip)Cl2] (1a) was also synthesized and structurally and magnetically characterized: this compound exhibits slow relaxation of magnetization under an applied dc field (1800 Oe) with a record slow relaxation time of 3.39 s at 1.8 K.
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Affiliation(s)
- Indrani Bhowmick
- Department of Chemistry, Colorado State University, Fort Collins, CO 80523-1872, USA.
| | - Brian S Newell
- Department of Chemistry, Colorado State University, Fort Collins, CO 80523-1872, USA. and Analytical Resources Core, Center for Materials and Molecular Analysis, Colorado State University, Fort Collins, Colorado 80523, USA
| | - Matthew P Shores
- Department of Chemistry, Colorado State University, Fort Collins, CO 80523-1872, USA.
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Mitsuhashi R, Hosoya S, Suzuki T, Sunatsuki Y, Sakiyama H, Mikuriya M. Zero-field slow relaxation of magnetization in cobalt(ii) single-ion magnets: suppression of quantum tunneling of magnetization by tailoring the intermolecular magnetic coupling. RSC Adv 2020; 10:43472-43479. [PMID: 35519684 PMCID: PMC9058397 DOI: 10.1039/d0ra08286d] [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: 09/28/2020] [Accepted: 11/23/2020] [Indexed: 12/03/2022] Open
Abstract
The correlation between magnetic relaxation dynamics and the alignment of single-ion magnets (SIMs) in a crystal was investigated using four analogous cobalt(ii) complexes with unique hydrogen-bond networks. The hydrogen-bonding interactions in the crystals resulted in a relatively short intermolecular Co⋯Co distance, which led to non-zero intermolecular magnetic coupling. All the complexes with a Co⋯Co distance shorter than 6.5 Å exhibited zero-field slow magnetic relaxation as weak magnetic interactions split the ground ±Ms levels and suppressed quantum tunneling of magnetization (QTM). In particular, antiferromagnetically coupled one-dimensional chain SIM networks effectively suppressed QTM when the two intrachain Co⋯Co distances were non-equivalent. However, when the two distances in a chain were equivalent and each molecular symmetry axis aligned parallell within the chain, QTM suppression was insufficient because magnetic coupling from the adjacent molecules was virtually cancelled. Partial substitution of the CoII ion with the diamagnetic ZnII ion up to 33% for this complex resulted in complete QTM suppression in the absence of an external field. These results show that the manipulation of intermolecular distances and alignments is effective for suppressing undesired QTM events in SIMs. Quenching of quantum tunneling of magnetization was observed in a tetrahedral cobalt(ii) complex with 1-D chain hydrogen-bond networks by partially substituting the CoII ion with the ZnII ion, up to 33%.![]()
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Affiliation(s)
- Ryoji Mitsuhashi
- Institute of Liberal Arts and Science, Kanazawa University Kakuma Kanazawa Ishikawa 920-1192 Japan
| | - Satoshi Hosoya
- School of Science and Technology, Kwansei Gakuin University 2-1 Gakuen Sanda Hyogo 669-1337 Japan
| | - Takayoshi Suzuki
- Research Institute for Interdisciplinary Science, Okayama University 3-1-1 Tsushima-naka, Kita-ku Okayama 700-8530 Japan
| | - Yukinari Sunatsuki
- Department of Chemistry, Faculty of Science, Okayama University 3-1-1 Tsushima-naka, Kita-ku Okayama 700-8530 Japan
| | - Hiroshi Sakiyama
- Department of Science, Faculty of Science, Yamagata University 1-4-12 Kojirakawa Yamagata 990-8560 Japan
| | - Masahiro Mikuriya
- School of Science and Technology, Kwansei Gakuin University 2-1 Gakuen Sanda Hyogo 669-1337 Japan
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6
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Pan YZ, Hua QY, Lin LS, Qiu YB, Liu JL, Zhou AJ, Lin WQ, Leng JD. A slowly magnetic relaxing SmIII monomer with a D5h equatorial compressed ligand field. Inorg Chem Front 2020. [DOI: 10.1039/d0qi00326c] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
A D5h equatorial compressed ligand field of the central LnIII ion is achieved. The samarium complex is the first SmIII mono-nuclear complex with slow magnetic relaxation. The DyIII analogue, in contrast, relaxes much faster
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Affiliation(s)
- Yong-Ze Pan
- School of Chemistry and Chemical Engineering/Institute of Clean Energy and Materials/Guangzhou Key Laboratory for Clean Energy and Materials
- Guangzhou University No. 230 Wai Huan Xi Road
- Guangzhou Higher Education Mega Center
- Guangzhou 510006
- P. R. China
| | - Qiu-Yan Hua
- School of Chemistry and Chemical Engineering/Institute of Clean Energy and Materials/Guangzhou Key Laboratory for Clean Energy and Materials
- Guangzhou University No. 230 Wai Huan Xi Road
- Guangzhou Higher Education Mega Center
- Guangzhou 510006
- P. R. China
| | - Li-Shan Lin
- School of Chemistry and Chemical Engineering/Institute of Clean Energy and Materials/Guangzhou Key Laboratory for Clean Energy and Materials
- Guangzhou University No. 230 Wai Huan Xi Road
- Guangzhou Higher Education Mega Center
- Guangzhou 510006
- P. R. China
| | - Yi-Bo Qiu
- School of Chemistry and Chemical Engineering/Institute of Clean Energy and Materials/Guangzhou Key Laboratory for Clean Energy and Materials
- Guangzhou University No. 230 Wai Huan Xi Road
- Guangzhou Higher Education Mega Center
- Guangzhou 510006
- P. R. China
| | - Jun-Liang Liu
- Key Lab of Bioinorganic and Synthetic Chemistry of Ministry of Education
- School of Chemistry
- Sun Yat-Sen University
- Guangzhou 510275
- P. R. China
| | - Ai-Ju Zhou
- School of Chemistry and Chemical Engineering/Institute of Clean Energy and Materials/Guangzhou Key Laboratory for Clean Energy and Materials
- Guangzhou University No. 230 Wai Huan Xi Road
- Guangzhou Higher Education Mega Center
- Guangzhou 510006
- P. R. China
| | - Wei-Quan Lin
- School of Chemistry and Chemical Engineering/Institute of Clean Energy and Materials/Guangzhou Key Laboratory for Clean Energy and Materials
- Guangzhou University No. 230 Wai Huan Xi Road
- Guangzhou Higher Education Mega Center
- Guangzhou 510006
- P. R. China
| | - Ji-Dong Leng
- School of Chemistry and Chemical Engineering/Institute of Clean Energy and Materials/Guangzhou Key Laboratory for Clean Energy and Materials
- Guangzhou University No. 230 Wai Huan Xi Road
- Guangzhou Higher Education Mega Center
- Guangzhou 510006
- P. R. China
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7
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Das M, Basak D, Trávníček Z, Vančo J, Ray D. Entrapment of a Pseudo-Tetrahedral Co II Center by Thioether Sulfur Bound {Co 2 (μ-L)} Fragments: Synthesis, Field-Induced Single-Ion Magnetism and Catechol Oxidase Mimicking Activity. Chem Asian J 2019; 14:3898-3914. [PMID: 31545553 DOI: 10.1002/asia.201901109] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2019] [Revised: 09/22/2019] [Indexed: 11/06/2022]
Abstract
Simultaneous incorporation of both CoII and CoIII ions within a new thioether S-bearing phenol-based ligand system, H3 L (2,6-bis-[{2-(2-hydroxyethylthio)ethylimino}methyl]-4-methylphenol) formed [Co5 ] aggregates [CoII CoIII 4 L2 (μ-OH)2 (μ1,3 -O2 CCH3 )2 ](ClO4 )4 ⋅H2 O (1) and [CoII CoIII 4 L2 (μ-OH)2 (μ1,3 -O2 CC2 H5 )2 ](ClO4 )4 ⋅H2 O (2). The magnetic studies revealed axial zero-field splitting (ZFS) parameter, D/hc=-23.6 and -24.3 cm-1 , and E/D=0.03 and 0.00, respectively for 1 and 2. Dynamic magnetic data confirmed the complexes as SIMs with Ueff /kB =30 K (1) and 33 K (2), and τ0 =9.1×10-8 s (1), and 4.3×10-8 s (2). The larger atomic radius of S compared to N gave rise to less variation in the distortion of tetrahedral geometry around central CoII centers, thus affecting the D and Ueff /kB values. Theoretical studies also support the experimental findings and reveal the origin of the anisotropy parameters. In solutions, both 1 and 2 which produce {CoIII 2 (μ-L)} units, display solvent-dependent catechol oxidation behavior toward 3,5-di-tert-butylcatechol in air. The presence of an adjacent CoIII ion tends to assist the electron transfer from the substrate to the metal ion center, enhancing the catalytic oxidation rate.
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Affiliation(s)
- Manisha Das
- Department of Chemistry, Indian Institute of Technology, Kharagpur, 721 302, India
| | - Dipmalya Basak
- Department of Chemistry, Indian Institute of Technology, Kharagpur, 721 302, India
| | - Zdeněk Trávníček
- Division of Biologically Active Complexes and Molecular Magnets, Faculty of Science, Palacký University, Šlechtitelů 27, 783 71, Olomouc, Czech Republic
| | - Ján Vančo
- Division of Biologically Active Complexes and Molecular Magnets, Faculty of Science, Palacký University, Šlechtitelů 27, 783 71, Olomouc, Czech Republic
| | - Debashis Ray
- Department of Chemistry, Indian Institute of Technology, Kharagpur, 721 302, India
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