Supramolecular assembly of ligand-directed triangular {Cu<sup>II</sup><sub>3</sub>Cl} clusters with spin frustration and spin-chain behaviour

Seeber, Georg; Kögerler, Paul; Kariuki, Benson M.; Cronin, Leroy

doi:10.1039/b402487g

Cited by 68 publications

(52 citation statements)

References 19 publications

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“…The Lieb-Schultz-Mattis theorem [24] would suggest that the spin gap must be accompanied with at least doublydegenerate ground state with a spontaneous breaking of the translational symmetry since the unit cell consists of three spins. From the experimental point of view, 1D coordination polymers [(CuCl 2 tachH) 3 Cl]Cl 2 (tach=1,3,5-triaminocyclohexane) [25][26][27] and Cu 2 Cl 4 · D 8 C 4 SO 2 [28] provide unique experimental realizations of a spin-1/2 Heisenberg three-leg and four-leg tube, respectively.…”

Section: Introductionmentioning

confidence: 99%

Spin frustration of a spin-1/2 Ising–Heisenberg three-leg tube as an indispensable ground for thermal entanglement

Strečka

Alécio

Lyra

et al. 2016

Journal of Magnetism and Magnetic Materials

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The spin-1/2 Ising-Heisenberg three-leg tube composed of the Heisenberg spin triangles mutually coupled through the Ising inter-triangle interaction is exactly solved in a zero magnetic field. By making use of the local conservation for the total spin on each Heisenberg spin triangle the model can be rigorously mapped onto a classical composite spin-chain model, which is subsequently exactly treated through the transfer-matrix method. The ground-state phase diagram, correlation functions, concurrence, Bell function, entropy and specific heat are examined in detail. It is shown that the spin frustration represents an indispensable ground for a thermal entanglement, which is quantified with the help of concurrence. The specific heat displays diverse temperature dependences, which may include a sharp low-temperature peak mimicking a temperature-driven first-order phase transition. It is convincingly evidenced that this anomalous peak originates from massive thermal excitations from the doubly degenerate ground state towards an excited state with a high macroscopic degeneracy due to chiral degrees of freedom of the Heisenberg spin triangles.

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Section: Introductionmentioning

confidence: 99%

Spin frustration of a spin-1/2 Ising–Heisenberg three-leg tube as an indispensable ground for thermal entanglement

Strečka

Alécio

Lyra

et al. 2016

Journal of Magnetism and Magnetic Materials

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“…transTach [17] is particularly versatile owing to the rigidity of its cyclohexane backbone which prevents the interaction of all three amino donor groups with one single metal center and a bis(axial)-mono(equatorial) of the amine groups is invariably observed upon coordination to open-shell transition-metal cations. In our case, the trans-tach ligand can simultaneously act as a bis-chelating ligand while the protonated terminal trans amine group can also help anchor the complex into supramolecular hydrogen-bonded networks.…”

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confidence: 99%

Structural and Compositional Control in {M₁₂} Cobalt and Nickel Coordination Clusters Detected Magnetochemically and with Cryospray Mass Spectrometry

et al. 2007

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Full compositional and structural control in the high-nuclearity coordination clusters of transition-metal cations is a crucial synthetic target, and is motivated by these species complex electronic and magnetic properties which single them out as metalloenzyme models, [1] nanoscale containers and catalysts, [2] quantum computing components, [3] and molecular magnets.[4] Strategies for their synthesis range from the use of multifunctional organic ligands [5] to the controlled production of molecular sections of solid-state structures, such as those of transition-metal oxides.[6] In most instances the resulting metal frameworks are derived from various archetypal condensed substructures, such as (distorted) M 4 L 4 cubanes (M = metal, L = O, N, etc.). Such cubanes constitute a class of discrete compounds such as complexes based on Ni 4 O 4 or Co 4 O 4 structures, which themselves represent sections of their respective oxides. For the past four decades, these species have been studied as precursors for metal oxide nanoparticles, [7] novel magnetic materials, [8] and polymerization catalysts.[9] Coordination complexes of higher nuclearity, such as {Ni 11 }, [10] or {Co 14 } [11] frequently comprise corner-, edge-, or face-sharing aggregates of M II 4 O II 4 . As such, the generation of isostructural metalligand frameworks is especially important as they allow systematic, comparative studies of their complex magnetic phenomena and the possibility to precisely position heterometal atoms within a given architecture. However, while several almost isostructural compounds of Ni II and Co II exist, including M 4 O 4 cubane structures, because of their very similar coordination chemistry, [12] these are invariably of low nuclearity, and systems exceeding ten metal centers are rare.[13] Correspondingly, mixed-metal isostructures (i.e. structures incorporating both Ni II and Co II centers in varying ratios that are distributed over the metal framework of a coordination cluster) can be generated, yet site-specific occupation is frequently subject to binomial statistics and cannot be resolved by diffraction techniques. In such situations, as we demonstrate herein, magnetic properties can be used to discern between the possible intramolecular distribution scenarios and indicate how narrow the distribution curves are for (cocrystallizing) compositions (of the typeHerein, we demonstrate the use of templating and multifunctional ligands to facilitate the directed assembly of archetypal isostructural Ni [14]These clusters comprise three M 4 O 4 cubane units symmetrically arranged around a central templating carbonate anion and the intact clusters {M 12 } can be detected in solution using cryospray mass spectrometry.[15] Moreover, isostructural mixed Ni:Co clusters of specific composition can be accessed since the pH value of the reaction solution (i.e. an additional reaction parameter besides the stoichiometric reaction ratio of Ni and Co) is used to differentiate the relative population of the metal sites in the {M 12 } system. ...

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“…10 for Fe30 and Ref. 13 for the Cu spin tube. The NMR measurements were performed utilizing a homemade phase-coherent spinecho pulsed NMR spectrometer on 1 H nuclei (nuclear spin I = 1/2 and gyromagnetic ratio γ N /2π = 42.5774 MHz/T) and 51 V nuclei (I = 7/2 and γ N /2π = 11.193 MHz/T) in the T range 0.1 K ≤ T ≤ 300 K using a 3 He- 4 He dilution refrigerator (Kelvinox MX100, Oxford instruments) installed at the Ames Laboratory by the author.…”

Section: Methodsmentioning

confidence: 92%

Review of NMR studies of nanoscale molecular magnets composed of geometrically frustrated antiferromagnetic triangles

Furukawa

2016

IJNT

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We present a comprehensive review of nuclear magnetic resonance (NMR) studies performed on three nanoscale molecular magnets with different configurations of geometrically frustrated antiferromagnetic (AFM) triangles, new spin frustration systems with different novel structures: (1) the isolated single AFM triangle K6[V15As6O42(H2O)]·8H2O (in short V15), (2) the spin ball [Mo72Fe30O252(Mo2O7(H2O))2 (Mo2O8H2(H2O))(CH3COO)12(H2O)91]·150H2O (in short Fe30 spin ball), and (3) the twisted triangular spin tube [(CuCl2tachH)3Cl]Cl2 (in short Cu3 spin tube). In the V15 nanomagnet, from 51 V NMR spectra observed at only below ∼ 0.1 K, we directly determined the local spin configuration in both the nonfrustrated total spin ST = 3/2 state at higher magnetic fields (H ≥ 2.7 T) and the two nearly degenerate ST = 1/2 ground states at lower magnetic fields (H ≤ 2.7 T). The dynamical magnetic properties of V15 were investigated by proton spin-lattice relaxation rate (1/T1) measurements. In the ST = 3/2 state, 1/T1 shows thermally activated behavior as a function of temperature. On the other hand, a temperature independent behavior of 1/T1 at very low temperatures is observed in the frustrated ST = 1/2 ground state below 2.7 Tesla. Possible origins for the peculiar behavior of 1/T1 will be discussed in terms of magnetic fluctuations due to spin frustrations. In Fe30 spin ball, static and dynamical properties of Fe 3+ (s = 5/2) have been investigated by proton NMR spectra and 1/T1 measurements. From the temperature dependence of 1/T1, the fluctuation frequency of the Fe 3+ spins is found to decrease with decreasing temperature, indicating spin freezing at low temperatures. The spin freezing is also evidenced by the observation of a sudden broadening of 1 H NMR spectra below 0.6 K. Finally 1 H NMR data in the Cu spin tube will be described. An observation of magnetic broadening of 1 H NMR spectra at low temperatures below 1 K directly revealed a gapless ground state of the system. The 1/T1 measurements revealed an usual slow spin dynamics in the quasi one dimensional Cu3 spin tube.

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Supramolecular assembly of ligand-directed triangular {Cu^II₃Cl} clusters with spin frustration and spin-chain behaviour

Cited by 68 publications

References 19 publications

Spin frustration of a spin-1/2 Ising–Heisenberg three-leg tube as an indispensable ground for thermal entanglement

Spin frustration of a spin-1/2 Ising–Heisenberg three-leg tube as an indispensable ground for thermal entanglement

Structural and Compositional Control in {M₁₂} Cobalt and Nickel Coordination Clusters Detected Magnetochemically and with Cryospray Mass Spectrometry

Review of NMR studies of nanoscale molecular magnets composed of geometrically frustrated antiferromagnetic triangles

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Supramolecular assembly of ligand-directed triangular {CuII3Cl} clusters with spin frustration and spin-chain behaviour

Cited by 68 publications

References 19 publications

Spin frustration of a spin-1/2 Ising–Heisenberg three-leg tube as an indispensable ground for thermal entanglement

Spin frustration of a spin-1/2 Ising–Heisenberg three-leg tube as an indispensable ground for thermal entanglement

Structural and Compositional Control in {M12} Cobalt and Nickel Coordination Clusters Detected Magnetochemically and with Cryospray Mass Spectrometry

Review of NMR studies of nanoscale molecular magnets composed of geometrically frustrated antiferromagnetic triangles

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Supramolecular assembly of ligand-directed triangular {Cu^II₃Cl} clusters with spin frustration and spin-chain behaviour

Structural and Compositional Control in {M₁₂} Cobalt and Nickel Coordination Clusters Detected Magnetochemically and with Cryospray Mass Spectrometry