Metal Substitution Effect on a Three-Dimensional Cyanido-Bridged Fe Spin-Crossover Network

Imoto, Kenta; Takano, Shinjiro; Ohkoshi, Shin‐ichi

doi:10.3390/inorganics5040063

Cited by 5 publications

(6 citation statements)

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“…The variation of the cooperativity in SCO solids is an important focus of research and is particularly appealing in terms of controlling abruptness, hysteresis width, shape, and degree of completeness of the thermal SCO behavior and can be investigated in combination with the structural changes around the metal centers that propagates across the entire solid. ,, One of the most potent chemical tools to explore such variation is to dilute the SCO solid with diamagnetic and paramagnetic dopants (i.e., metal ions) that, on one side, control the strength of the interactions among the SCO centers ,,,,− and, on the other side, impact the HS → LS thermal equilibrium (thus, Δ E 0 HL between two spin manifolds) and the shape, width, completeness, and abruptness of the thermal hysteresis. Therefore, the influence of the metal dilution in the cooperative SCO solids is often considered significant.…”

Section: Introductionmentioning

confidence: 99%

Variation of the Cooperativity in Diluted Hofmann-Based Spin-Crossover Coordination Solids {Fe_1–xM_x(pz)[Pd(CN)₄]}

Das

Dey

Adak

et al. 2023

Crystal Growth & Design

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This work is devoted to the investigation of the influence of dopants on the cooperativity of 3D Hofmann-based spin-crossover solids {Fe 1−x M x (pz)-[Pd(CN) 4 ]}, as reflected in the abruptness, position, shape, and completeness of the thermal spin transition and on the width of accompanying hysteresis loop. We present systematic experimental studies, including FTIR, powder X-ray diffraction, energy-dispersive X-ray analysis, and magnetic susceptibility measurements for pure and diluted compounds using Zn, Ni, Mn, and Co as dopants. The shift of the thermal transition temperature toward lower temperatures is, in most cases, correlated with the dopant sizes and the effective dilution. By using a 3D mechanoelastic model considering the different sizes of dopants and the change in intermolecular interactions induced by them, we have satisfactorily reproduced the observed macroscopic experimental behavior. In addition, the microscopic scale images obtained during the HS-LS thermal transition show how the presence of the dopants prevents the spreading of the clusters, reducing the cooperativity in the system.

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Section: Introductionmentioning

confidence: 99%

Variation of the Cooperativity in Diluted Hofmann-Based Spin-Crossover Coordination Solids {Fe_1–xM_x(pz)[Pd(CN)₄]}

Das

Dey

Adak

et al. 2023

Crystal Growth & Design

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“…They indicate that the parallel configuration of coordinated pyridine rings in an FeN 6 coordination core favors the HS state. Imoto and co-workers [19] demonstrate the metal dilution effect on SCO cooperativity for the cyano-bridged Fe(II) SCO network and reveal that the decrease in cooperativity by increasing Co(II) concentration may lead to more gradual SCO transitions and lower transition temperatures. For the development of novel multifunctional SCO hybrid compounds, Kuramochi and co-workers [20] develop Fe(II) SCO hybrid molecular systems with a polyoxometalate (POM) anion, which is known as a multi-functional unit.…”

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confidence: 96%

Spin-Crossover Complexes

Takahashi

2018

Inorganics

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Spin-crossover (SCO) is a spin-state switching phenomenon between a high-spin (HS) and low-spin (LS) electronic configurations in a transition metal center. The SCO phenomenon is widely recognized as an example of molecular bistability. The SCO compounds most widely studied are six-coordinate first-row transition metal complexes with d 4 -d 7 configurations. A relative small enthalpy variation between LS and HS states can be realized by coopetition between ligand field stabilization (LFS) and spin pairing energies, which is illustrated by the Tanabe-Sugano diagrams in common coordination chemistry textbooks. Since an entropy variation in spin multiplicity from LS to HS is always positive, an increase in temperature can induce the transformation in Gibbs free energy from a positive to a negative sign, at which point SCO conversion occurs from the LS to HS state.Cambi and co-workers' pioneering work on the anomalous magnetic behaviors of mononuclear Fe(III) dithiocarbamate complexes [1] was first recognized as SCO phenomena in the early 1930s. However, progress on SCO complexes awaited the dissemination of ligand field theory into coordination chemistry. The concept of controlling LFS energies by substitution with different field strength ligands resulted in the corroboration of SCO phenomena in some Co(II) and Fe(II) complexes in the early 1960s. Moreover, subsequent findings that pressure [2] and light [3] can induce an SCO phenomenon may attract attention to SCO complexes. In the 1990s the demonstration of device applications using the SCO complex [4] illuminated the potential of SCO complexes in future practical applications in memory, display, and sensing devices. Figure 1 shows the number of published articles per year whose titles or topics contain the words "spin-crossover," "spin equilibrium," or their derivatives. Studies concerning SCO complexes have apparently increased since the 1980s; moreover, the number has more rapidly developed after the 2000s. The fundamentals and applications of SCO complexes have attracted growing interest not only in inorganic coordination chemistry but also in a wide range of relevant research fields.

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“…These chains are linked by Fe1 complexes creating the Mo–Fe1–Mo linkages positioned along both a and c crystallographic axes. Such combined intermetallic bridging modes ensure the trigonal coordination framework crystallizing in the R 3̅ c space group, which is very different from the typically observed tetragonal coordination network based on divalent transition-metal ions and [M IV (CN) 8 ] 4– (M = Mo, W, Nb) metalloligands. − This can be explained by the presence of three distinguishable six-coordinated octahedral Fe II complexes detected in FeMo (Figures b and and S2). The Fe1 centers, which combine the 12-metal rings of coordination nanotubes along the c axis, coordinate two bridging cyanides in a trans configuration and four 3-OAcpy ligands, resulting in the [Fe1(μ-NC) 2 (3-OAcpy) 4 ] composition.…”

Section: Resultsmentioning

confidence: 74%

“…The presence of Fe II centers surrounded by N atoms of cyanides and N atoms of pyridine derivatives suggests the possible occurrence of a thermal SCO effect. − Therefore, the temperature variable X-ray diffraction studies for the selected single crystal of FeMo , and the polycrystalline sample of FeNb , were performed (Tables S1 and S4, Figures S5–S6). The space group and the whole view of the 3-D coordination frameworks of FeMo and FeNb remain unchanged with decreasing temperature.…”

Section: Resultsmentioning

confidence: 99%

“…with extra functionalities, including luminescence, , optical activity, , second harmonic generation, and proton conductivity . [M(CN) 8 ]-based heterometallic frameworks have been fruitfully used for synthesis of molecule-based switches, exploring magnetic sponge-like behavior, thermo- or photoswitchable charge-transfer phase transitions, and photoinduced spin switching of [Mo/W(CN) 8 ] 4– ions. − The [M(CN) 8 ] n − building blocks have been also employed in the preparation of SCO materials based on Fe II . ,− The best results were found for the relatively rare, paramagnetic [Nb IV (CN) 8 ] 4– ion, which together with Fe II produced a series of tetragonal 3-D coordination networks, {[Fe II (L) 4 ] 2 [Nb IV (CN) 8 ]}· n (solvent) (L = pyridine derivatives or pyrazole). − They enabled the unique discoveries of a light-induced SCO magnet, pressure-induced SCO-based photomagnetism, and the 90° photoswitching of second harmonic light in a chiral SCO photomagnet . In addition, the extremely rare [Re V (CN) 8 ] 3– ion combined with Fe II enabled the observation of thermal SCO effect in the nanosized {Fe 9 [Re(CN) 8 ] 6 } coordination clusters. , Following these results, we aimed at the application of Fe II (L)–[M(CN) 8 ] n − system for the generation of multistep SCO phenomenon.…”

Section: Introductionmentioning

confidence: 99%

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In Situ Ligand Transformation for Two-Step Spin Crossover in Fe^II[M^IV(CN)₈]^4– (M = Mo, Nb) Cyanido-Bridged Frameworks

et al. 2019

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We report a unique synthetic route toward the multistep spin crossover (SCO) effect induced by utilizing the partial ligand transformation during the crystallization process, which leads to the incorporation of three different Fe II complexes into a single coordination framework. The 3acetoxypyridine (3-OAcpy) molecules were introduced to the self-assembled Fe II −[M IV (CN) 8 ] 4− (M = Mo, Nb) system in the aqueous solution which results in the partial hydrolysis of the ligand into 3-hydroxypyridine (3-OHpy). It gives two novelThey exhibit an unprecedented cyanido-bridged skeleton composed of {Fe 3 M 2 } n coordination nanotubes bonded by additional Fe complexes. These frameworks contain three types of Fe sites differing in the attached organic ligands, [Fe1(3-OAcpy) 4 (μ-NC) 2 ], [Fe2(3-OHpy) 4 (μ-NC) 2 ], and [Fe3(3-OAcpy) 3 (3-OHpy)(μ-NC) 2 ], which lead to the thermal two-step Fe II SCO, as proven by X-ray diffraction, magnetic susceptibility, UV− vis−NIR optical absorption, and 57 Fe Mossbauer spectroscopy studies. The first step of SCO, going from room temperature to the 150−170 K range with transition temperatures of 245(5) and 283(5) K for FeMo and FeNb, respectively, is related to Fe1 sites, while the second step, occurring at the 50−140 K range with transition temperatures of 70(5) and 80(5) K for FeMo and FeNb, respectively, is related to Fe2 sites. The Fe3 site with both 3-OAcpy and 3-OHpy ligands does not undergo the SCO at all. The observed two-step SCO phenomenon is explained by the differences in the ligand field strength of the Fe complexes and the role of their alignment in the coordination framework. The simultaneous application of two related pyridine derivatives is the efficient synthetic route for the multistep Fe II SCO in the cyanido-bridged framework which is a promising step toward rational design of advanced spin transition molecular switches.

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Metal Substitution Effect on a Three-Dimensional Cyanido-Bridged Fe Spin-Crossover Network

Cited by 5 publications

References 58 publications

Variation of the Cooperativity in Diluted Hofmann-Based Spin-Crossover Coordination Solids {Fe_1–xM_x(pz)[Pd(CN)₄]}

Variation of the Cooperativity in Diluted Hofmann-Based Spin-Crossover Coordination Solids {Fe_1–xM_x(pz)[Pd(CN)₄]}

Spin-Crossover Complexes

In Situ Ligand Transformation for Two-Step Spin Crossover in Fe^II[M^IV(CN)₈]^4– (M = Mo, Nb) Cyanido-Bridged Frameworks

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Metal Substitution Effect on a Three-Dimensional Cyanido-Bridged Fe Spin-Crossover Network

Cited by 5 publications

References 58 publications

Variation of the Cooperativity in Diluted Hofmann-Based Spin-Crossover Coordination Solids {Fe1–xMx(pz)[Pd(CN)4]}

Variation of the Cooperativity in Diluted Hofmann-Based Spin-Crossover Coordination Solids {Fe1–xMx(pz)[Pd(CN)4]}

Spin-Crossover Complexes

In Situ Ligand Transformation for Two-Step Spin Crossover in FeII[MIV(CN)8]4– (M = Mo, Nb) Cyanido-Bridged Frameworks

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Variation of the Cooperativity in Diluted Hofmann-Based Spin-Crossover Coordination Solids {Fe_1–xM_x(pz)[Pd(CN)₄]}

Variation of the Cooperativity in Diluted Hofmann-Based Spin-Crossover Coordination Solids {Fe_1–xM_x(pz)[Pd(CN)₄]}

In Situ Ligand Transformation for Two-Step Spin Crossover in Fe^II[M^IV(CN)₈]^4– (M = Mo, Nb) Cyanido-Bridged Frameworks