Special Issue "A Themed Issue of Functional Molecule-based Magnets: Dedicated to Professor Masahiro Yamashita on the Occasion of his 65th Birthday"

A special issue of Magnetochemistry (ISSN 2312-7481).

Deadline for manuscript submissions: closed (30 June 2019).

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A printed edition of this Special Issue is available here.

Special Issue Editor

Dr. Keiichi Katoh
Website
Guest Editor
Department of Chemistry, Graduate School of Science, Tohoku University, Sendai, Japan
Interests: molecule-based magnets; multifunctional molecules; molecule-based spintronic materials; single molecule chemistry and physics; spinterface science

Special Issue Information

Dear Colleagues,

Since research on molecule-based magnetic materials was systematized in the 1980s, the field has expanded greatly. In Magnetochemistry, a Special Issue focusing on molecule-based magnetic substances will be published in honor of Professor Masahiro Yamashita's 65th birthday.

Masahiro Yamashita received his D.Sc. in 1982 from Kyushu University. Then, he joined the Institute for Molecular Science (IMS). In 1985, he was appointed Assistant Professor at Kyushu University. In 1989, he was appointed Associate Professor at Nagoya University. He was a full Professor at Tokyo Metropolitan University from 2000 to 2004. He is now a full Professor in Tohoku University. He has been honored with the Inoue Scientific Award (2002), the Chemical Society of Japan Award for Creative Work (2005), and the Award of Japan Society of Coordination Chemistry (2014). He is now an Associate Member of the Science Council of Japan. He is also Associate Editor of Dalton Transactions, as well as a Fellow of the Royal Society of Chemistry (FRSC).

The field of molecule-based magnetic materials has developed across many fields, such as chemistry, physics, material chemistry, and applied physics, and the use of the various functionalities of these molecule-based magnetic substances strongly influences research on spin-based devices. Molecule-based magnetic materials include a wide variety of molecular compounds, such as organic radicals, transition metal complexes, and rare earth complexes, and exhibit magnetic properties not only as single molecules, but also in various forms, such as crystals, liquid crystals, thin films, and macromolecular polymers. Research on light, magnetic field, and electric field responsive molecule-based magnetic materials is still vigorous, and the development of multiferroic, spintronic, and molecular-based QC materials is expected. At the same time, research on the application of these materials as spin-based memories and devices by detecting and controlling the spin state at the molecular level, known as the spinterface, has been a hot topic in recent years. In other words, it is possible to combine the ideas and concepts from the study of spintronics into the development of molecular spin systems and to realize nanospintronic devices by using carefully designed molecule-based magnets.

For this Special Issue of Magnetochemistry, we are gathering contributions from various areas of functional molecule-based magnets. I would like to cordially invite you to submit an article to this Special Issue. Original research articles, perspectives, reviews, and personal accounts that fit into one of the key topics listed below are welcome. Furthermore, this Special Issue is in honor of Professor Masahiro Yamashita, who has contributed greatly to this field, on the occasion of his 65th birthday.

Dr. Keiichi Katoh
Guest Editor

Manuscript Submission Information

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Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Magnetochemistry is an international peer-reviewed open access quarterly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 1400 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Keywords

  • Molecule-based magnets
  • Multifunctional molecule-based magnets
  • Switchable molecule-based magnets
  • Molecule-based spintronic materials
  • Spin control and detection system
  • Spinterface science
  • Molecular spintronics
  • Molecular spin QC vicinity phenomenon
  • Theoretical approach of multifunctional molecule-based magnets

Published Papers (11 papers)

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Editorial

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Open AccessEditorial
Special Issue: A Themed Issue of Functional Molecule-Based Magnets: Dedicated to Professor Masahiro Yamashita on the Occasion of His 65th Birthday
Magnetochemistry 2020, 6(2), 17; https://doi.org/10.3390/magnetochemistry6020017 - 07 Apr 2020
Abstract
Research on molecule-based magnetic materials was systematized in the 1980s and expanded rapidly [...] Full article
Open AccessEditorial
Laudation: In Celebration of Masahiro Yamashita’s 65th Birthday
Magnetochemistry 2019, 5(2), 25; https://doi.org/10.3390/magnetochemistry5020025 - 10 Apr 2019
Cited by 1
Abstract
Professor Masahiro Yamashita at the Tohoku University, Japan, celebrates his 65th birthday in 2019 [...] Full article

Research

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Open AccessArticle
Theoretical Study on Magnetic Interaction in Pyrazole-Bridged Dinuclear Metal Complex: Possibility of Intramolecular Ferromagnetic Interaction by Orbital Counter-Complementarity
Magnetochemistry 2020, 6(1), 10; https://doi.org/10.3390/magnetochemistry6010010 - 26 Feb 2020
Cited by 1
Abstract
A possibility of the intramolecular ferromagnetic (FM) interaction in pyrazole-bridged dinuclear Mn(II), Fe(II), Co(II), and Ni(II) complexes is examined by density functional theory (DFT) calculations. When azide is used for additional bridging ligand, the complexes indicate the strong antiferromagnetic (AFM) interaction, while the [...] Read more.
A possibility of the intramolecular ferromagnetic (FM) interaction in pyrazole-bridged dinuclear Mn(II), Fe(II), Co(II), and Ni(II) complexes is examined by density functional theory (DFT) calculations. When azide is used for additional bridging ligand, the complexes indicate the strong antiferromagnetic (AFM) interaction, while the AFM interaction becomes very weak when acetate ligand is used. In the acetate-bridged complexes, an energy split of the frontier orbitals suggests the orbital counter-complementarity effect between the dxy orbital pair, which contributes to the FM interaction; however, a significant overlap of other d-orbital pairs also suggests an existence of the AFM interaction. From those results, the orbital counter-complementarity effect is considered to be canceled out by the overlap of other d-orbital pairs. Full article
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Open AccessArticle
Relationship between the Coordination Geometry and Spin Dynamics of Dysprosium(III) Heteroleptic Triple-Decker Complexes
Magnetochemistry 2019, 5(4), 65; https://doi.org/10.3390/magnetochemistry5040065 - 26 Nov 2019
Cited by 1
Abstract
When using single molecule magnets (SMMs) in spintronics devices, controlling the quantum tunneling of the magnetization (QTM) and spin-lattice interactions is important. To improve the functionality of SMMs, researchers have explored the effects of changing the coordination geometry of SMMs and the magnetic [...] Read more.
When using single molecule magnets (SMMs) in spintronics devices, controlling the quantum tunneling of the magnetization (QTM) and spin-lattice interactions is important. To improve the functionality of SMMs, researchers have explored the effects of changing the coordination geometry of SMMs and the magnetic interactions between them. Here, we report on the effects of the octa-coordination geometry on the magnetic relaxation processes of dinuclear dysprosium(III) complexes in the low-temperature region. Mixed ligand dinuclear Dy3+ triple-decker complexes [(TPP)Dy(Pc)Dy(TPP)] (1), which have crystallographically equivalent Dy3+ ions, and [(Pc)Dy(Pc)Dy(TPP)] (2), which have non-equivalent Dy3+ ions, (Pc2− = phthalocyaninato; TPP2− = tetraphenylporphyrinato), undergo dual magnetic relaxation processes. This is due to the differences in the ground states due to the twist angle (φ) between the ligands. The relationship between the off-diagonal terms and the dual magnetic relaxation processes that appears due to a deviation from D4h symmetry is discussed. Full article
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Open AccessFeature PaperArticle
Diversity of Coordination Modes in a Flexible Ditopic Ligand Containing 2-Pyridyl, Carbonyl and Hydrazone Functionalities: Mononuclear and Dinuclear Cobalt(III) Complexes, and Tetranuclear Copper(II) and Nickel(II) Clusters
Magnetochemistry 2019, 5(3), 39; https://doi.org/10.3390/magnetochemistry5030039 - 01 Jul 2019
Cited by 2
Abstract
Syntheses, crystal structures and characterization are reported for four new complexes [Cu4Br2(L)4]Br2 (1), [Ni4(NO3)2(L)4(H2O)](NO3)2 (2), [Co2(L)3 [...] Read more.
Syntheses, crystal structures and characterization are reported for four new complexes [Cu4Br2(L)4]Br2 (1), [Ni4(NO3)2(L)4(H2O)](NO3)2 (2), [Co2(L)3](ClO4)3 (3) and [Co(L)2](ClO4) (4), where L is the monoanion of the ditopic ligand N′-(1-(pyridin-2-yl)ethylidene)pyridine-2-carbohydrazide (LH) built on a picolinoyl hydrazone core fragment, and possessing a bidentate and a tridentate coordination pocket. The tetranuclear cation of 1·0.8H2O·MeOH is a strictly planar, rectangular [2 × 2] grid. Two 2.21011 L ligands bridge adjacent CuII atoms on the short sides of the rectangle through their alkoxide oxygen atoms, and two 2.11111 ligands bridge adjacent CuII atoms on the long sides of the rectangle through their diazine groups; two metal ions are 5-coordinate and two are 6-coordinate. The tetranuclear cation of 2·0.2H2O·3EtOH is a square [2 × 2] grid. The two 6-coordinate NiII atoms of each side of the square are bridged by the alkoxide O atom of one 2.21011 L ligand. The dinuclear cation of 3·0.8H2O·1.3MeOH contains two low-spin octahedral CoIII ions bridged by three 2.01111 L ligands forming a pseudo triple helicate. In the mononuclear cation [Co(L)2]+ of complex 4, the low-spin octahedral CoIII center is coordinated by two tridentate chelating, meridional 1.10011 ligands. The crystal structures of the complexes are stabilized by a variety of π–π stacking and/or H-bonding interactions. Compounds 2, 3 and 4 are the first structurally characterized nickel and cobalt complexes of any form (neutral or anionic) of LH. The 2.01111 and 1.10011 coordination modes of L, observed in the structures of complexes 3 and 4, have been crystallographically established for the first time in coordination complexes containing this anionic ligand. Variable-temperature, solid-state dc magnetic susceptibility and variable-field magnetization studies at 1.8 K were carried out on complexes 1 and 2. Antiferromagnetic metal ion···metal ion exchange interactions are present in both complexes. The study reveals that the cation of 1 can be considered as a practically isolated pair of strongly antiferromagnetically coupled (through the diazine group of L) dinulear units. The susceptibility data for 2 were fit to a single-J model for an S = 1 cyclic tetramer. The values of the J parameters have been rationalized in terms of known magnetostructural correlations. Spectral data (infrared (IR), ultraviolet/visible (UV/VIS), 1H nuclear magnetic resonance (NMR) for the diamagnetic complexes) are also discussed in the light of the structural features of 14 and the coordination modes of the organic and inorganic ligands that are present in the complexes. The combined work demonstrates the ligating flexibility of L, and its usefulness in the synthesis of complexes with interesting structures and properties. Full article
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Open AccessFeature PaperArticle
A Novel Family of Triangular CoII2LnIII and CoII2YIII Clusters by the Employment of Di-2-Pyridyl Ketone
Magnetochemistry 2019, 5(2), 35; https://doi.org/10.3390/magnetochemistry5020035 - 04 Jun 2019
Cited by 2
Abstract
The synthesis, structural characterization and magnetic study of novel CoII/4f and CoII/YIII clusters are described. In particular, the initial employment of di-2-pyridyl ketone, (py)2CO, in mixed metal Co/4f chemistry, provided access to four triangular clusters, [Co [...] Read more.
The synthesis, structural characterization and magnetic study of novel CoII/4f and CoII/YIII clusters are described. In particular, the initial employment of di-2-pyridyl ketone, (py)2CO, in mixed metal Co/4f chemistry, provided access to four triangular clusters, [CoII2MIII{(py)2C(OEt)(O)}4(NO3)(H2O)]2[M(NO3)5](ClO4)2 (M = Gd, 1; Dy, 2; Tb, 3; Y, 4), where (py)2C(OEt)(O) is the monoanion of the hemiketal form of (py)2CO. Clusters 14 are the first reported Co/4f (13) and Co/Y (4) species bearing (py)2CO or its derivatives, despite the fact that over 200 metal clusters bearing this ligand have been reported so far. Variable-temperature, solid-state dc and ac magnetic susceptibility studies were carried out on 14 and revealed the presence of weak ferromagnetic exchange interactions between the metal ions (JCo-Co = +1.3 and +0.40 cm−1 in 1 and 4, respectively; JCo-Gd = +0.09 cm−1 in 1). The ac susceptibility studies on 2 revealed nonzero, weak out-of-phase (χ’’M) signals below ~5 K. Full article
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Open AccessFeature PaperArticle
Chloranilato-Based Layered Ferrimagnets with Solvent-Dependent Ordering Temperatures
Magnetochemistry 2019, 5(2), 34; https://doi.org/10.3390/magnetochemistry5020034 - 04 Jun 2019
Cited by 1
Abstract
We report the synthesis and the characterization of six new heterometallic chloranilato-based ferrimagnets formulated as (NBu4)[MnCr(C6O4Cl2)3]·nG with n = 1 for G = C6H5Cl (1), C6 [...] Read more.
We report the synthesis and the characterization of six new heterometallic chloranilato-based ferrimagnets formulated as (NBu4)[MnCr(C6O4Cl2)3]·nG with n = 1 for G = C6H5Cl (1), C6H5I (3), and C6H5CH3 (4); n = 1.5 for G = C6H5Br (2) and n = 2 for G = C6H5CN (5) and C6H5NO2 (6); (C6O4Cl2)2− = 1,3-dichloro,2,5-dihydroxy-1,4-benzoquinone dianion. The six compounds are isostructural and show hexagonal honeycomb layers of the type [MnCr(C6O4Cl2)3] alternating with layers containing the NBu4+ cations. The hexagons are formed by alternating Mn(II) and Cr(III) connected by bridging bis-bidentate chloranilato ligands. The benzene derivative solvent molecules are located in the hexagonal channels (formed by the eclipsed packing of the honeycomb layers) showing π-π interactions with the anilato rings. The six compounds behave as ferrimagnets with ordering temperatures in the range 9.8–11.2 K that can be finely tuned by the donor character of the benzene ring and by the number of solvent molecules inserted in the hexagonal channels. The larger the electron density on the aromatic ring and the larger the number of solvent molecules are, the higher Tc is. The only exception is provided by toluene, where the formation of H-bonds might be at the origin of weaker π-π interactions observed in this compound. Full article
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Open AccessArticle
How to Quench Ferromagnetic Ordering in a CN-Bridged Ni(II)-Nb(IV) Molecular Magnet? A Combined High-Pressure Single-Crystal X-Ray Diffraction and Magnetic Study
Magnetochemistry 2019, 5(2), 33; https://doi.org/10.3390/magnetochemistry5020033 - 01 Jun 2019
Cited by 2
Abstract
High-pressure (HP) structural and magnetic properties of a magnetic coordination polymer {[NiII(pyrazole)4]2[NbIV(CN)8]·4H2O}n (Ni2Nb) are presented, discussed and compared with its two previously reported analogs {[MnII(pyrazole)4 [...] Read more.
High-pressure (HP) structural and magnetic properties of a magnetic coordination polymer {[NiII(pyrazole)4]2[NbIV(CN)8]·4H2O}n (Ni2Nb) are presented, discussed and compared with its two previously reported analogs {[MnII(pyrazole)4]2[NbIV(CN)8]·4H2O}n (Mn2Nb) and {[FeII(pyrazole)4]2[NbIV(CN)8]·4H2O}n (Fe2Nb). Ni2Nb shows a significant decrease of the long-range ferromagnetic ordering under high pressure when compared to Mn2Nb, where the pressure enhances the Tc (magnetic ordering temperature), or to Fe2Nb exhibiting a pressure-induced spin crossover. The different HP magnetic responses of the three compounds were rationalized and correlated with the structural models as determined by single-crystal X-ray diffraction. Full article
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Open AccessArticle
Series of Chloranilate-Bridged Dinuclear Lanthanide Complexes: Kramers Systems Showing Field-Induced Slow Magnetic Relaxation
Magnetochemistry 2019, 5(2), 30; https://doi.org/10.3390/magnetochemistry5020030 - 02 May 2019
Cited by 2
Abstract
A series of chloralilate-bridged dinuclear lanthanide complexes of formula [{LnIII(Tp)2}2(μ-Cl2An)]·2CH2Cl2, where Cl2An2− and Tp represent the chloranilate and hydrotris (pyrazolyl)borate ligands, respectively, and Ln = Gd ( [...] Read more.
A series of chloralilate-bridged dinuclear lanthanide complexes of formula [{LnIII(Tp)2}2(μ-Cl2An)]·2CH2Cl2, where Cl2An2− and Tp represent the chloranilate and hydrotris (pyrazolyl)borate ligands, respectively, and Ln = Gd (1), Tb (2), Ho (3), Er (4), and Yb (5) was synthesized. All five complexes were characterized by an elemental analysis, infrared spectroscopy, single crystal X-ray diffraction, and SQUID measurements. The complexes 15 in the series were all isostructural. A comparison of the temperature dependence of the dc magnetic susceptibility data of these complexes revealed clear differences depending on the lanthanide center. Ac magnetic susceptibility measurements revealed that none of the five complexes exhibited a slow magnetic relaxation under a zero applied dc field. On the other hand, the Kramers systems (complexes 4 and 5) clearly displayed a slow magnetic relaxation under applied dc fields, suggesting field-induced single-molecule magnets that occur through Orbach and Raman relaxation processes. Full article
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Open AccessArticle
Correlation between Slow Magnetic Relaxations and Molecular Structures of Dy(III) Complexes with N5O4 Nona-Coordination
Magnetochemistry 2019, 5(2), 27; https://doi.org/10.3390/magnetochemistry5020027 - 18 Apr 2019
Cited by 1
Abstract
A series of Dy(III) mononuclear complexes [DyA2L]+ (L denotes Schiff base N5 ligand that occupies equatorial positions and A denotes bidentate anionic O-donor ligands such as NO3 (1), AcO (2), [...] Read more.
A series of Dy(III) mononuclear complexes [DyA2L]+ (L denotes Schiff base N5 ligand that occupies equatorial positions and A denotes bidentate anionic O-donor ligands such as NO3 (1), AcO (2), and acac (3)) were synthesized to investigate the correlation between the slow magnetic relaxation phenomena and the coordination structures around Dy(III). The Dy(III) ion in each complex is in a nona-coordination with the anionic O-donor ligand occupying up- and down-side positions of the N5 equatorial plane. 2 and 3 show slow magnetic relaxation phenomena under a zero bias-field condition, and all complexes showed slow magnetic relaxation under the applied 1000-Oe bias-field conditions. Arrhenius analyses revealed that the ΔE/kB, the barrier height for magnetization flipping, increases in this order, with the values of 24.1(6), 85(3), and 140(15) K. The effects of the exchanging axial ligands on the magnetic anisotropy were discussed together with the DFT calculations. Full article
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Open AccessArticle
Pressure Effects with Incorporated Particle Size Dependency in Graphene Oxide Layers through Observing Spin Crossover Temperature
Magnetochemistry 2019, 5(2), 26; https://doi.org/10.3390/magnetochemistry5020026 - 11 Apr 2019
Cited by 1
Abstract
This research highlights the pressure effects with the particle size dependency incorporated in two-dimensional graphene oxide (GO)/reduced graphene oxide (rGO). GO and rGO composites employing nanorods (NRs) of type [Fe(Htrz)2(trz)](BF4) have been prepared, and their pressure effects in the [...] Read more.
This research highlights the pressure effects with the particle size dependency incorporated in two-dimensional graphene oxide (GO)/reduced graphene oxide (rGO). GO and rGO composites employing nanorods (NRs) of type [Fe(Htrz)2(trz)](BF4) have been prepared, and their pressure effects in the interlayer spaces through observing the changes of the spin crossover (SCO) temperature (T1/2) have been discussed. The composites show the decrease of interlayer spaces from 8.7 Å to 3.5 Å that is associated with GO to rGO transformation. The shorter interlayer spaces were induced by pressure effects, resulting in the increment of T1/2 from 357 K to 364 K. The pressure effects in the interlayers spaces estimated from the T1/2 value correspond to 24 MPa in pristine [Fe(Htrz)2(trz)](BF4) NRs under hydrostatic pressure. The pressure observed in the composites incorporating NRs (30 × 200 nm) is smaller than that observed in the composite incorporating nanoparticles (NPs) (30 nm). These results clearly demonstrated that the incorporated particle size and shape influenced the pressure effects between the GO/rGO layer. Full article
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