Christianity: The Basics

Chilton, Bruce

doi:10.4324/9781315765440

Cited by 3 publications

(4 citation statements)

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“…The presence of two relaxation processes SR (slow relaxation at high temperature) and FR (fast relaxation at low temperature) could be due to the existence of two different Dy III centers in the structure. The fit of the Cole–Cole plot (Figure S8) to the Debye model with the CCFIT program afforded the temperature dependence of the relaxation times for the SR and FR relaxation processes. The fit of these data to the Arrhenius law (Figure c) led to the following parameters U eff = 54.7 K and τ 0 = 1.7(3) × 10 –6 s and U eff = 47.8 K and τ 0 = 1.5(4) × 10 –8 s for the SR and FR relaxation processes, respectively.…”

Section: Resultsmentioning

confidence: 99%

Designing a Dy₂ Single-Molecule Magnet with Two Well-Differentiated Relaxation Processes by Using a Nonsymmetric Bis-bidentate Bipyrimidine-N-Oxide Ligand: A Comparison with Mononuclear Counterparts

et al. 2018

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Herein we report a dinuclear [(μ-mbpymNO){(tmh)Dy}] (1) single-molecule magnet (SMM) showing two nonequivalent Dy centers, which was rationally prepared from the reaction of Dy(tmh) moieties (tmh = 2,2,6,6-tetramethyl-3,5-heptanedionate) and the asymmetric bis-bidentate bridging ligand 4-methylbipyrimidine (mbpymNO). Depending on whether the Dy ions coordinate to the N^O or N^N bidentate donor sets, the Dy sites present a NO ( D geometry) or NO ( D) coordination sphere. As a consequence, two different thermally activated magnetic relaxation processes are observed with anisotropy barriers of 47.8 and 54.7 K. Ab initio calculations confirm the existence of two different relaxation phenomena and allow one to assign the 47.8 and 54.7 K energy barriers to the Dy(NO) and Dy(NO) sites, respectively. Two mononuclear complexes, [Dy(tta)(mbpymNO)] (2) and [Dy(tmh)(phenNO)] (3), have also been prepared for comparative purposes. In both cases, the Dy center shows a NO coordination sphere and SMM behavior is observed with U values of 71.5 K (2) and 120.7 K (3). In all three cases, ab initio calculations indicate that relaxation of the magnetization takes place mainly via the first excited-state Kramers doublet through Orbach, Raman, and thermally assisted quantum-tunnelling mechanisms. Pulse magnetization measurements reveal that the dinuclear and mononuclear complexes exhibit hysteresis loops with double- and single-step structures, respectively, thus supporting their SMM behavior.

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Section: Resultsmentioning

confidence: 99%

Designing a Dy₂ Single-Molecule Magnet with Two Well-Differentiated Relaxation Processes by Using a Nonsymmetric Bis-bidentate Bipyrimidine-N-Oxide Ligand: A Comparison with Mononuclear Counterparts

et al. 2018

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“…In view of this, the relaxation times were extracted for each process, fitting the data in the 2.5-8.0 K range by using a sum of two modified Debye functions with the CCFIT software. 22 It is worth mentioning that the software provides τ and α values for the two processes in the whole temperature range. Nonetheless, taking into account that each process operates or predominates in a certain temperature range, Arrhenius plots were constructed individually in the 2.5-5.5 K and 5.5-8.0 K temperature ranges for SR and FR, respectively.…”

Section: Magnetic Propertiesmentioning

confidence: 99%

2D-Coordination polymers based on 1H-indazole-4-carboxylic acid and transition metal ions: magnetic, luminescence and biological properties

et al. 2020

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“…The field dependence of the χ M ″ v frequency plot (Figure S38) at 2.5 K clearly shows the presence of two relaxation processes. These data were fitted to a sum of two independent relaxation processes using the generalized Debye model and the CCFIT software, which allowed the extraction of the field dependence of the relaxation times for both processes. (Figure S38).…”

Section: Resultsmentioning

confidence: 99%

“…In the χ M ″ vs T plot, below 3000 Hz, the latter peaks overlap with those in the low-temperature region so that no clear maxima are observed in the high-temperature region. The Cole–Cole plot clearly exhibits the two relaxation processes, and therefore, these data were fitted to the sum of two independent processes using the CCFIT software, allowing extracting the temperature dependence of the relaxation times for the fast (FR) and the slow (SR) relaxation processes (Figure ). The extracted τ vs T data for the FR process were fitted to a combination of direct and Orbach processes (eq ) where the first term corresponds to the direct relaxation process.…”

Section: Resultsmentioning

confidence: 99%

Synthesis, Structure, and Zero-Field SMM Behavior of Homometallic Dy2, Dy4, and Dy6 Complexes

et al. 2022

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The synthesis, structure, and magnetic properties of three DyIII complexes of different nuclearity, [Dy2(H2L)2(NO3)] [NO3]·2H2O·CH3OH (1), [Dy4(HL)2(piv)4(OH)2] (2), and [Dy6(H2L)3(μ3–OH)(μ3–CO3)3(CH3OH)4(H2O)8] 5Cl·3H2O (3) [(H4L) = 6-((bis(2-hydroxyethyl)amino)-N′-(2-hydroxybenzylidene)picolinohydrazide)], are described. This variety of complexes with the same ligand could be obtained by playing with the metal-to-ligand molar ratio, the type of DyIII salt, the kind of base, and the presence/absence of coligand. 1 is a dinuclear complex, while 2 is a tetranuclear assembly with a butterfly-shaped topology. 3 is a homometallic hexanuclear complex that exhibits a propeller-shaped topology. Interestingly, in this complex 3, three atmospheric carbon dioxide molecules are trapped in the form of carbonate ions, which assist in holding the hexanuclear complex together. All of the complexes reveal a slow relaxation of magnetization even in zero applied field. Complex 1 is a zero-field SMM with an effective energy barrier (U eff) of magnetization reversal equal to 87(1) K and a relaxation time of τ0 = 6.4(3) × 10–9 s. Under an applied magnetic field of 0.1 T, these parameters change to U eff = 101(3) K, τ0 = 2.5(1) × 10–9 s. Complex 2 shows zero-field SMM behavior with U eff = 31(2) K, τ0 = 4.2(1) × 10–7 s or τ01 = 2(1) × 10–7 s, U eff1 = 37(8) K, τ02 = 5(6) × 10–5 s, and U eff2 = 8(4) by considering two Orbach relaxation processes, while 3, also a zero-field SMM, shows a double relaxation of magnetization [U eff1 = 62.4(3) K, τ01 = 4.6(3) × 10–8 s, and U eff1 = 2(1) K, τ02 = 4.6(2) × 10–5 s]. The ab initio calculations indicated that in these complexes, the Kramer’s ground doublet is characterized by an axial g-tensor with the prevalence of the m J = ±15/2 component, as well as that due to the weak magnetic coupling between the metal centers, the magnetic relaxation, which is dominated by the single DyIII centers rather than by the exchange-coupled states, takes place via Raman/Orbach or TA-QTM. Moreover, theoretical calculations support a toroidal magnetic state for complex 2.

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Christianity: The Basics

Cited by 3 publications

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Designing a Dy₂ Single-Molecule Magnet with Two Well-Differentiated Relaxation Processes by Using a Nonsymmetric Bis-bidentate Bipyrimidine-N-Oxide Ligand: A Comparison with Mononuclear Counterparts

Designing a Dy₂ Single-Molecule Magnet with Two Well-Differentiated Relaxation Processes by Using a Nonsymmetric Bis-bidentate Bipyrimidine-N-Oxide Ligand: A Comparison with Mononuclear Counterparts

2D-Coordination polymers based on 1H-indazole-4-carboxylic acid and transition metal ions: magnetic, luminescence and biological properties

Synthesis, Structure, and Zero-Field SMM Behavior of Homometallic Dy2, Dy4, and Dy6 Complexes

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Christianity: The Basics

Cited by 3 publications

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Designing a Dy2 Single-Molecule Magnet with Two Well-Differentiated Relaxation Processes by Using a Nonsymmetric Bis-bidentate Bipyrimidine-N-Oxide Ligand: A Comparison with Mononuclear Counterparts

Designing a Dy2 Single-Molecule Magnet with Two Well-Differentiated Relaxation Processes by Using a Nonsymmetric Bis-bidentate Bipyrimidine-N-Oxide Ligand: A Comparison with Mononuclear Counterparts

2D-Coordination polymers based on 1H-indazole-4-carboxylic acid and transition metal ions: magnetic, luminescence and biological properties

Synthesis, Structure, and Zero-Field SMM Behavior of Homometallic Dy2, Dy4, and Dy6 Complexes

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Designing a Dy₂ Single-Molecule Magnet with Two Well-Differentiated Relaxation Processes by Using a Nonsymmetric Bis-bidentate Bipyrimidine-N-Oxide Ligand: A Comparison with Mononuclear Counterparts

Designing a Dy₂ Single-Molecule Magnet with Two Well-Differentiated Relaxation Processes by Using a Nonsymmetric Bis-bidentate Bipyrimidine-N-Oxide Ligand: A Comparison with Mononuclear Counterparts