Vanadium Octacyanoniobate-Based Magnet with a Curie Temperature of 138 K

In this work, we prepared a three-dimensional vanadium octacyanoniobate-based magnet, K0.10VII0.54VIII1.24[NbIV(CN)8]·(SO4)0.45·6.8H2O. This compound exhibits ferrimagnetism with a Curie temperature of 138 K, in which the sublattice magnetizations of VII (S = 3/2) and VIII (S = 1) are antiparallelly ordered to that of NbIV (S = 1/2). The estimated superexchange interaction constants of VII−NbIV and VIII−NbIV are −51 and −25 cm−1, respectively

Vanadium(II) Heptacyanomolybdate(III)-Based Magnet Exhibiting a High Curie Temperature of 110 K

We prepared a vanadium heptacyanomolybdate-based magnet, VII2[MoIII(CN)7]·(pyrimidine)2·4.5H2O (VMo), with a Curie temperature (TC) of 110 K, which is the highest TC value in [MoIII(CN)7]-based magnets. Additionally, MnII2[MoIII(CN)7]·(pyrimidine)2·2H2O (MnMo) of a monoclinic structure (P21/n) with TC = 47 K was prepared to confirm the crystal structure of VMo

Vanadium(II) Heptacyanomolybdate(III)-Based Magnet Exhibiting a High Curie Temperature of 110 K

We prepared a vanadium heptacyanomolybdate-based magnet, VII2[MoIII(CN)7]·(pyrimidine)2·4.5H2O (VMo), with a Curie temperature (TC) of 110 K, which is the highest TC value in [MoIII(CN)7]-based magnets. Additionally, MnII2[MoIII(CN)7]·(pyrimidine)2·2H2O (MnMo) of a monoclinic structure (P21/n) with TC = 47 K was prepared to confirm the crystal structure of VMo

High Thermal Durability of Water-Free Copper-Octacyanotungsten-Based Magnets Containing Halogen Bonds

Two-dimensional (2-D) cyano-bridged Cu–W bimetallic assemblies that include halogen-substituted pyridine molecules, [Cu^II(3-iodopyridine)₄][Cu^II(3-iodopyridine)₂]₂[W^V(CN)₈]₂ (<b>1</b>) (triclinic crystal structure, <i>P</i>1̅ space group), [Cu^II(3-bromopyridine)₄][Cu^II(3-bromopyridine)₂]₂[W^V(CN)₈]₂ (<b>2</b>) (triclinic, <i>P</i>1̅), and [Cu^II(3-chloropyridine)₂(H₂O)₂][Cu^II(3-chloropyridine)₂]₂[W^V(CN)₈]₂·4H₂O (<b>3</b>) (monoclinic, <i>P</i>2₁/<i>c</i>), were synthesized. Thermogravimetric measurements demonstrate that <b>1</b> and <b>2</b> have high thermal durability up to ca. 150 °C (423 K) due to the lack of water molecules in the crystal and the stacked Cu–W 2-D layers with halogen bonding between halogen-substituted pyridine and the cyano nitrogen of octacyanotungstate. In contrast, <b>3</b> exhibits weight loss above ca. 50 °C (323 K) as the water molecules between the 2-D layers are removed upon heating. Magnetic measurements show that <b>1</b>–<b>3</b> are ferromagnets due to parallel ordering of the magnetic spins on Cu^II (<i>S</i> = 1/2) and W^V (<i>S</i> = 1/2) with Curie temperatures (<i>T</i>_C) of 4.7 K (<b>1</b>), 5.2 K (<b>2</b>), and 7.2 K (<b>3</b>)

Crystal Structure, Charge-Transfer-Induced Spin Transition, and Photoreversible Magnetism in a Cyano-Bridged Cobalt−Tungstate Bimetallic Assembly

This paper describes the crystal structure, magnetic properties, and photoreversible magnetic properties of CoII3[WV(CN)8]2(pyrimidine)4·6H2O. We found that complexes of this formula had two types of crystal structures ([{CoII(pyrimidine)2}2{CoII(H2O)2}{WV(CN)8}2]·4H2O (1) and [{CoII(pyrimidine)(H2O)}2{CoII(H2O)2}{WV(CN)8}2](pyrimidine)2·2H2O (2)). These two structures had similar metal−organic frameworks but differed in the coordination environment around Co1, i.e., Co1(NC)4(pyrimidine)2 in 1 and Co1(NC)4(pyrimidine)(H2O) in 2. In 1, a temperature-induced phase transition from the CoII (S = 3/2)−NC−WV (S = 1/2) [high-temperature (HT)] phase to the CoIII (S = 0)−NC−WIV (S = 0) [low-temperature (LT)] phase was observed due to a charge-transfer-induced spin transition. However, 2 did not exhibit such a phase transition. When the LT phase of 1 was irradiated by 840 nm light, ferromagnetism with a Curie temperature of 40 K and magnetic coercive field of 12 kOe were observed. UV–vis reflectance and infrared measurements suggested that the LT phase optically transited to the photoinduced (PI) phase, which had a similar valence state as the HT phase, through the metal-to-metal charge-transfer (WIV → CoIII) band. In contrast, when the back metal-to-metal charge transfer (CoII → WV) band of the PI phase was excited by 532 nm light, the reverse phase transition from the PI phase to the LT phase occurred, and the spontaneous magnetization decreased

Crystal Structure, Charge-Transfer-Induced Spin Transition, and Photoreversible Magnetism in a Cyano-Bridged Cobalt−Tungstate Bimetallic Assembly

This paper describes the crystal structure, magnetic properties, and photoreversible magnetic properties of CoII3[WV(CN)8]2(pyrimidine)4·6H2O. We found that complexes of this formula had two types of crystal structures ([{CoII(pyrimidine)2}2{CoII(H2O)2}{WV(CN)8}2]·4H2O (1) and [{CoII(pyrimidine)(H2O)}2{CoII(H2O)2}{WV(CN)8}2](pyrimidine)2·2H2O (2)). These two structures had similar metal−organic frameworks but differed in the coordination environment around Co1, i.e., Co1(NC)4(pyrimidine)2 in 1 and Co1(NC)4(pyrimidine)(H2O) in 2. In 1, a temperature-induced phase transition from the CoII (S = 3/2)−NC−WV (S = 1/2) [high-temperature (HT)] phase to the CoIII (S = 0)−NC−WIV (S = 0) [low-temperature (LT)] phase was observed due to a charge-transfer-induced spin transition. However, 2 did not exhibit such a phase transition. When the LT phase of 1 was irradiated by 840 nm light, ferromagnetism with a Curie temperature of 40 K and magnetic coercive field of 12 kOe were observed. UV–vis reflectance and infrared measurements suggested that the LT phase optically transited to the photoinduced (PI) phase, which had a similar valence state as the HT phase, through the metal-to-metal charge-transfer (WIV → CoIII) band. In contrast, when the back metal-to-metal charge transfer (CoII → WV) band of the PI phase was excited by 532 nm light, the reverse phase transition from the PI phase to the LT phase occurred, and the spontaneous magnetization decreased

High Proton Conductivity in Prussian Blue Analogues and the Interference Effect by Magnetic Ordering

High Proton Conductivity in Prussian Blue Analogues and the Interference Effect by Magnetic Orderin

Synthesis and Alcohol Vapor Sensitivity of a Ferromagnetic Copper−Tungsten Bimetallic Assembly

A copper(II) octacyanotungsten(V)-based ferromagnet, CuII3[WV(CN)8]2(pyrimidine)2·8H2O, was prepared. This magnetic material can reversibly adsorb and desorb n-propanol vapor and shows reversible variations in the crystal structure and magnetic properties. These changes are due to the coordination geometry switching of CuII between 6-coordinate and 5-coordinate

Spin Crossover by Encapsulation

Spin Crossover by Encapsulatio

Spin Crossover by Encapsulation

Spin Crossover by Encapsulatio