Influence of magnetic dilution on relaxation processes in a solid solution comprising tetrahedral Co/Zn<sup>II</sup> complexes

Ceglarska, Magdalena; Stefańczyk, Olaf; Ohkoshi, Shin‐ichi; Majcher, Anna M.

doi:10.1039/d0dt01058h

Cited by 8 publications

(11 citation statements)

References 36 publications

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“…resulted in an increase in the energy barrier to 27.1 K. SMM behavior was also reported for similar Co(II)-Y(III) benzoate or 9-anthracenecarboxylate complexes [ 111 ]. Similar results were obtained by Ceglarska et al for Co x Zn 1–x Br 2 (pyridine) 2 complexes [ 112 ]. A decrease in cobalt(II) concentration from 91 to 6 at.% resulted in an energy barrier increase from 14 to 27 K. In metal–organic frameworks, the dilution of the cobalt(II) paramagnetic centers in a diamagnetic matrix was also reported as a possible strategy for the creation of SIM or SMM porous materials.…”

Section: Resultssupporting

confidence: 90%

Aerogel-Based Single-Ion Magnets: A Case Study of a Cobalt(II) Complex Immobilized in Silica

et al. 2023

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The chemical immobilization of cobalt(II) ions in a silica aerogel matrix enabled the synthesis of the first representative example of aerogel-based single-ion magnets. For the synthesis of the lyogels, methyl-trimethoxysilane and N-3-(trimethoxysilyl)propyl ethylenediamine were co-hydrolyzed, then the ethylenediamine groups that were immobilized on the silica matrix enabled the subsequent binding of cobalt(II) ions. Lyogels with various amounts of ethylenediamine moieties (0.1–15 mol %) were soaked in isopropanol solutions of cobalt(II) nitrate and further supercritically dried in carbon dioxide to obtain aerogels with a specific surface area of 210–596 m2·g−1, an apparent density of 0.403–0.740 cm3·g−1 and a porosity of 60–78%. The actual cobalt content in the aerogels was 0.01–1.50 mmol per 1 g of SiO2, which could easily be tuned by the concentration of ethylenediamine moieties in the silica matrix. The introduction of cobalt(II) ions into the ethylenediamine-modified silica aerogel promoted the stability of the diamine moieties at the supercritical drying stage. The molecular prototype of the immobilized cobalt(II) complex, bearing one ethylenediamine ligand [Co(en)(MeCN)(NO3)2], was synthesized and structurally characterized. Using magnetometry in the DC mode, it was shown that cobalt(II)-modified silica aerogels exhibited slow magnetic relaxation in a nonzero field. A decrease in cobalt(II) concentration in aerogels from 1.5 mmol to 0.14 mmol per 1 g of SiO2 resulted in a weakening of inter-ion interactions; the magnetization reversal energy barrier likewise increased from 4 to 18 K.

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Section: Resultssupporting

confidence: 90%

Aerogel-Based Single-Ion Magnets: A Case Study of a Cobalt(II) Complex Immobilized in Silica

et al. 2023

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“…Ceglarska and co-workers also have reported very recently that the creation of the two frequency domains observed in a six-coordinated Co(II) SMM [CoBr 2 (pyridine) 2 ] is of intermolecular origin by using a similar systematic study of magnetic dilution. 47 These studies clearly indicate that the occurrence of multiple relaxation pathways is attributed to the presence of intermolecular interactions.…”

Section: ■ Results and Discussionmentioning

confidence: 88%

Water Molecule-Induced Reversible Magnetic Switching in a Bis-Terpyridine Cobalt(II) Complex Exhibiting Coexistence of Spin Crossover and Orbital Transition Behaviors

et al. 2020

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The development of molecule-based switchable materials remains an important challenge in the field of molecular science. Achievement of a structural phase transition induced by adsorption/desorption of guest molecules in spin crossover (SCO) Co(II) compounds is of significant interest because of the possibility that the spin state of the magnetic anisotropic high-spin (HS, S = 3/2) and low-spin (LS, S = 1/2) states can be switched via the induced changes in associated intermolecular interactions. In this study, we demonstrated a reversible magnetic switching associated with spin state conversion, along with a single-crystal to single-crystal (SCSC) phase transition induced by dehydration/rehydration. [Co(terpy)2](BF4)2·H2O (1·H2O; terpy = 2,2′:6′,2′′-terpyridine) assembles in the solid state via π–π and CH−π interactions involving adjacent terpyridine cores along the ab direction to form two-dimensional (2D) layered domains. 1·H2O exhibits gradual and incomplete SCO, from fully HS to ca. 0.5 HS, and the field-induced single-molecule magnet (SMM) behavior attributed to the presence of the anisotropic partial high-spin Co(II) species. 1·H2O undergoes a SCSC transformation accompanied by a change from the tetragonal space group I41/a to P42/n via a dehydration process. Dehydrated 1 exhibits a reverse thermal hysteresis behavior (T 1/2↑ = 287 K; T 1/2↓ = 270 K) in the gradual SCO region from fully HS to ca. 0.5 HS, followed by an ordinary thermal hysteresis (T′1/2↑ = 195 K; T′1/2↓ = 155 K) to fully LS Co(II). A temperature-dependent single-crystal X-ray structural analysis revealed that the reverse hysteresis can be attributed to an order/disorder structural phase transition of the BF4 – anions involving a symmetry breaking to yield the monoclinic space group P21/n and orbital (angular momentum) transition (LT). Both the SCSC phase transition and magnetic behavior are switchable by dehydration/rehydration processes; thus 1 again adsorbs water at room temperature to give both the original structure and its magnetic behavior.

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“…9–11 The anisotropic Co( ii ) complexes have been deeply studied with the results of various Co( ii )-based SIMs with different coordination geometries and environments, 12–19 among which the four-coordinate Co-SIMs are of particular interest. Most of the reported four-coordinate Co( ii )-SIMs usually contain a mixed donor set from N, P, As, O, S, Se and/or halides with the coordination moieties such as [CoN 2 N′ 2 ], 20,21 [CoNN′ 3 ], 17,22,23 [CoN 2 O 2 ], 24–26 [CoN 2 S 2 ], 27 [CoL 2 X 2 ] (L 2 = N 2 , 28,29 P 2 , 30–37 O 2 , 38 S 2 , 33,39,40 C 2 , 41 X = halide), [CoN 3 X], 42 and [CoNX 3 ]. 43 The other family includes a smaller number of homoleptic SIMs containing a CoX 4 unit (X = O, 44 S, 44,45 Se, 44 Te, 46 N, 47 Cl 48 ) with four identical donors.…”

Section: Introductionmentioning

confidence: 99%

Magnetic anisotropy of two tetrahedral Co(ii)-halide complexes with triphenylphosphine ligands

Cui

Chen

et al. 2022

Dalton Trans.

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Influence of magnetic dilution on relaxation processes in a solid solution comprising tetrahedral Co/Zn^II complexes

Abstract: Dilution with diamagnetic species in a SIM solid solution leads to an increase in relaxation times at low temperatures and monotonously reduces the probability of quantum tunneling of magnetization and the direct process.

Cited by 8 publications

References 36 publications

Aerogel-Based Single-Ion Magnets: A Case Study of a Cobalt(II) Complex Immobilized in Silica

Aerogel-Based Single-Ion Magnets: A Case Study of a Cobalt(II) Complex Immobilized in Silica

Water Molecule-Induced Reversible Magnetic Switching in a Bis-Terpyridine Cobalt(II) Complex Exhibiting Coexistence of Spin Crossover and Orbital Transition Behaviors

Magnetic anisotropy of two tetrahedral Co(ii)-halide complexes with triphenylphosphine ligands

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Influence of magnetic dilution on relaxation processes in a solid solution comprising tetrahedral Co/ZnII complexes

Abstract: Dilution with diamagnetic species in a SIM solid solution leads to an increase in relaxation times at low temperatures and monotonously reduces the probability of quantum tunneling of magnetization and the direct process.

Cited by 8 publications

References 36 publications

Aerogel-Based Single-Ion Magnets: A Case Study of a Cobalt(II) Complex Immobilized in Silica

Aerogel-Based Single-Ion Magnets: A Case Study of a Cobalt(II) Complex Immobilized in Silica

Water Molecule-Induced Reversible Magnetic Switching in a Bis-Terpyridine Cobalt(II) Complex Exhibiting Coexistence of Spin Crossover and Orbital Transition Behaviors

Magnetic anisotropy of two tetrahedral Co(ii)-halide complexes with triphenylphosphine ligands

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Influence of magnetic dilution on relaxation processes in a solid solution comprising tetrahedral Co/Zn^II complexes