Strong Antiferromagnetic Coupling Research Articles

Three Reversible Redox States of Thiolate-Bridged Dirhodium Complexes without Metal–Metal Bonds

An unusual dinuclear rhodium complex with the anionic 2-mercapto-6-methylpyridinate (mmp) bridging ligand is reported which is capable of undergoing significant variations in its structural and coordination environments as a result of two reversible redox events at accessible potentials (E1/2 = 0.014, 0.52 V vs. Ag/AgCl). The large degree of separation between these redox states (ΔE = 0.51 V, KC = 4.17x108) allows for the chemical isolation of three distinct complexes 1, 2, and 3, in which the oxidation states of each Rh center are described as Rh2I,I, Rh2I,II, and Rh2II,II, respectively, and whose structures were elucidated by single crystal X-ray diffraction studies. Complex 2 is an unprecedented type of mixed valence dirhodium species whose EPR spectrum revealed a delocalization of the unpaired electron through the thiolate bridging ligand. Intervalence charge transfer (IVCT) occurs between the Rh centers as evidenced by a broad absorption in the near-infrared region (λmax¬=1187 nm). The structure of 3 is quite rare in that it lacks the typical RhII-RhII σ bond but significant orbital overlap between the Rh 4dz2 and S 3pz orbitals results in strong antiferromagnetic coupling (computed J = -1516.9 cm-1). Complex 3 also absorbs low energy light (λmax¬ = 779 nm) and spectroscopic and magnetic measurements are supported by DFT methods which further elucidate the nature of the ground state energies, frontier orbital characters, excitated state transitions, and the presence of weak Rh-Rh NBO interactions.

Robust half-metallicity and magnetic phase transition in Sr2CrReO6 via strain engineering

Using ab-initio calculations, the electronic and magnetic properties of double perovskite oxide {text{Sr}}_2 {text{CrReO}}_6 with two type of strains: biaxial (along the [110]-direction) and hydrostatic (along [111]-direction) are investigated. The ground state of the unstrained system is half-metallic ferrimagnetic, due to a strong antiferromagnetic (AFM) coupling between Cr and Re atoms within both (GGA and GGA+U) exchange-correlation potentials. It is demonstrated that the robustness of half-metallicity can be preserved under the influence of both biaxial and hydrostatic strains. Interestingly, a transition from ferri-to-ferromagnetic is established due to Re spin flipping to that of the Cr ion (i.e. Cr and Re spin becomes parallel) within the GGA+U method for both biaxial and hydrostatic tensile strains of ge +2%. The strong confinement of orbitals due to tensile strain results in the decrease of electron hopping which further reduced the AFM coupling strength between Cr and Re atoms, this leads to a ferri-to-ferromagnetic transition. However, the GGA scheme holds the ferrimagnetic state with both kinds of strains. This work shows that tensile strain is a feasible way to optimize the magnetic properties of perovskite oxides, which are presumed to be beneficial for spintronic technology.

Optimizing the Proton Conductivity of Fe-Diphosphonates by Increasing the Relative Number of Protons and Carrier Densities.

Proton conductive materials have attracted extensive interest in recent years due to their fascinating applications in sensors, batteries, and proton exchange membrane fuel cells. Herein, two Fe-diphosphonate chains (H4-BAPEN)0.5·[FeIII(H-HEDP)(HEDP)0.5(H2O)] (1) and (H4-TETA)2·[FeIII2FeII(H-HEDP)2(HEDP)2(OH)2]·2H2O (2) (HEDP = 1-hydroxyethylidenediphosphonate, BAPEN = 1,2-bis(3-aminopropylamino)ethane, and TETA = triethylenetetramine) with different templating agents were prepared by hydrothermal reactions. The valence states of the Fe centers were demonstrated by 57Fe Mössbauer spectra at 100 K, with a high-spin FeIII state for 1 and mixed high-spin FeIII/FeII states for 2. Their magnetic properties were determined, which featured strong antiferromagnetic couplings in the chain. Importantly, the proton conductivity of both compounds at 100% relative humidity was explored at different temperatures, with 2.79 × 10-4 S cm-1 at 80 °C for 1 and 7.55 × 10-4 S cm-1 at 45 °C for 2, respectively. This work provides an opportunity for improving proton conductive properties by increasing the relative number of protons and the carrier density using protonated flexible aliphatic amines.

Multiferroic properties of three-layer Aurivillius compound Bi[formula omitted]TiFeNbO12: A first-principles and experimental study

We present a first-principles and experimental study of the structural, ferroelectric, and magnetic properties of the potentially multiferroic three-layer Aurivillius compound Bi4TiFeNbO12. This system can be realized by inserting a BiFeO3 formula unit into the two-layer Aurivilius Bi3TiNbO9 matrix. The calculations are performed using the PBEsol exchange–correlation functional within the DFT+U framework. First we search for potential cation site preference by comparing the relative stability of different Fe, Nb and Ti arrangements. We find a preference for the Fe3＋ ions to occupy the inner site within the pseudoperovskite block. This configuration exhibits a band gap of 1.2 eV (UFe=4eV) and ferroelectric and magnetic orders. A value of 66 μC/cm2 is obtained for the spontaneous polarization, which is similar to the one obtained for Bi4Ti3O12 (BIT). The magnetic ground state of this system is characterized by a strong antiferromagnetic coupling between the Fe3＋ ions located in the central layer. By mapping to a Heisenberg model, the superexchange antiferromagnetic coupling between nearest-neighbor Fe3＋ cations is estimated to be J=53 meV. Finally, we synthesize Bi3.25La0.75TiFeNbO12 ceramics by the solid-state reaction method. Their structural, electric and magnetic properties are confronted with the theoretical predictions.

Current-induced CrI3 surface spin-flop transition probed by proximity magnetoresistance in Pt

By exploiting proximity coupling, we probe the spin state of the surface layers of CrI3, a van der Waals magnetic semiconductor, by measuring the induced magnetoresistance (MR) of Pt in Pt/CrI3 nano-devices. We fabricate the devices with clean and stable interfaces by placing freshly exfoliated CrI3 flake atop pre-patterned thin Pt strip and encapsulating the Pt/CrI3 heterostructure with hexagonal boron nitride (hBN) in a protected environment. In devices consisting of a wide range of CrI3 thicknesses (30–150 nm), we observe that an abrupt upward jump in Pt MR emerge at a 2 T magnetic field applied perpendicularly to the layers when the current density exceeds 2.5 × 1010 A m−2, followed by a gradual decrease over a range of 5 T. These distinct MR features suggest a spin-flop transition which reveals strong antiferromagnetic interlayer coupling in the surface layers of CrI3. We study the current dependence by holding the Pt/CrI3 sample at approximately the same temperature to exclude the joule heating effect, and find that the MR jump increases with the current density, indicating a spin current origin. This spin current effect provides a new route to control spin configurations in insulating antiferromagnets, which is potentially useful for spintronic applications.

Two new copper(II) binuclear complexes with 2-[(E)-(pyridine-2yl-hydrazono)methyl]phenol: Molecular structures, quantum chemical calculations, cryomagnetic properties and catalytic activity

The Schiff base is synthesized by the reaction of 2-hydrazinopyridine and salicylaldehyde. The copper(II) binuclear complexes [Cu2(µ-ClO4)(L)2(H2O)2](ClO4)·H2O(1) and [Cu2(µ-pyrazine)(L)2](ClO4)2(2)with 2-[(E)-(pyridine-2yl-hydrazono)methyl]phenol (HL), were synthesized and characterized using various physicochemical techniques. The molecular structures of both binuclear complexes were evaluated by single-crystal X-ray analysis. Analysis of the supramolecular synthons and their effect on crystal packing is conferred in the context of crystal engineering. The electron paramagnetic spectra are reported as well. The electrochemical behavior of both complexes was explored using cyclic voltammetry (CV) and differential pulse voltammetry (DPV) techniques. The electronic and spectral properties are described by quantum chemical calculations (TD and DFT).The cryomagnetic investigation (2–300 K) reveal antiferromagnetic exchange coupling between two copper(II) centres of different strength: JCuCu = −21.6 and JCuCu = -6.8 cm−1 for 1 and 2, respectively. The strong antiferromagnetic coupling between the copper centers found in 1 could be explained not only by magnetic exchange through hydrogen bonds but also through the π-π stacking of the Schiff base ligands. Both binuclear complexes exhibit catalytic activity toward the dismutation of superoxide anion at physiological pH. Although the activity in both complexes is lower than the native enzyme, they have potential as antioxidant SOD model for pharmaceutical applications.

Entanglement entropy in the spin-1/2 Heisenberg chain with hexamer modulation of exchange

The spin-1/2 isotropic alternating Heisenberg chains with hexamer modulation of exchange are considered. Recently, the ground state phase diagram of the model was obtained for different patterns of modulations in the limit of strong antiferromagnetic exchange coupling on odd links. In addition to the zero and saturated-magnetization plateaus, two gapped plateau states were recognized in the presence of a uniform magnetic field. Here, using the numerical Lanczos method, the ground state of finite chain systems is calculated and the behavior of the entanglement entropy (EE) and the concurrence is studied. First, we divided the chain system into two subsystems A and B and focus on EE which shows how much subsystems A and B are entangled. Results show that a pair of spins located on a strong antiferromagnetic link is entangled in the gapped mid plateau states. On the other hand, a pair of spins located on a weak link is completely entangled with the rest of the chain in the zero-magnetization plateau state. Second, we focused on the entanglement between nearest neighbor pair spins and the concurrence is calculated numerically. Pair spins on non-modulated links will be entangled only in the first or the second gapped plateau phases.

Synthesis and Magnon Thermal Transport Properties of Spin Ladder Sr14Cu24O41 Microstructures

AbstractThe spin ladder compound (Sr,Ca,La)14Cu24O41 exhibits an incommensurate layered structure with strong antiferromagnetic coupling. Besides intriguing superconducting behavior, recent experiments on bulk Sr14Cu24O41 single crystals have revealed a remarkable magnon thermal conductivity, which is the largest above 100 K among all known quantum magnets. Although bulk (Sr,Ca,La)14Cu24O41 crystals have been synthesized and studied extensively, there have been few reports on the synthesis and magnon thermal transport investigation of their microstructures. Here, the synthesis and thermal transport properties of Sr14Cu24O41 microrods are reported. Electron microscopy studies indicate that these microrods synthesized by a coprecipitation method are single crystals grown preferentially along the ladder axis. Based on a four‐probe thermal transport measurement, the thermal conductivity of the microrods reveals appreciable magnon transport in the microstructures. According to a kinetic model analysis, magnon transport in the microrods is suppressed mainly by increased point defect scattering compared to the bulk crystals, whereas surface scattering is negligible for anisotropic 1D magnon transport along the ladder. Moreover, the thermal conductivity is enhanced after annealing as a result of reduced oxygen vacancies. These results help to build the foundation for future heterogeneous integration of magnetic microstructures in microscale devices for the transport of energy and quantum information.

Gate modulation of the long-range magnetic order in a vanadium-doped WSe2 semiconductor

Generation of spin-charge coupling by doping semiconductors with magnetic dopants is a promising approach for gate-tunable spintronic devices without applying an external magnetic field. Here, we demonstrate that the magnetic orders in V-doped WSe2 can be modulated by tuning carrier densities using ab initio calculations. We found that at a low V-doping concentration limit, the long-range ferromagnetic order is enhanced by increasing the hole density. In contrast, this long-range ferromagnetic order is suppressed at high electron density by compensating the p-type V dopant, originating from the strong localized antiferromagnetic coupling between V and W atoms and between V and Se atoms. The hole-mediated long-range magnetic exchange is ∼70 meV, thus strongly suggesting the ferromagnetism in V-doped WSe2 at room temperature. Our findings on strong coupling between charge and spin order in V-doped WSe2 provide plenty of room for multifunctional gate-tunable spintronics.

Stepwise Oxidations in a Cofacial Copper(II) Porphyrin Dimer: Through-Space Spin-Coupling and Interplay between Metal and Radical Spins.

cis and trans-copper(II) porphyrin dimers have been synthesized, in which two CuII porphyrin macrocycles are bridged through a rigid ethene linker for possible through-space and through-bond spin-couplings between the paramagnetic CuII centers. It has been found that the two macrocycles come closer after 1 e- oxidation, however, they move far apart upon further 1 e- oxidation leading to transformation of the cis to the trans isomer. Detailed investigations are performed here on the interactions between the two porphyrin macrocycles, between two unpaired spins of closely spaced CuII centers, and also between the unpaired spins of metal and porphyrin π-cation radicals. Spectroscopic investigations along with the X-ray structure of the 2 e- -oxidized complex displayed strong electronic communications through the bridge between two porphyrin π-cation radicals. The counterion I9 - is stabilized in an unusual trigonal-pyramidal structure in the 2 e- -oxidized complex in which the central iodide ion is bound with four iodine (I2 ) molecules. Variable-temperature magnetic study revealed strong antiferromagnetic coupling between the two porphyrin π-cation radical spins (Jr-r ) in the 2 e- -oxidized complex. DFT calculations suggest stabilization of the triplet state, which is also in good agreement with the experiment. Ab initio molecular dynamics allowed the variation of the structural details to be followed upon stepwise oxidations and also the final isomerization process including its associated energy barrier.

New maximally disordered – High entropy intermetallic phases (MD-HEIP) of the Gd1-xLaxSn2-ySbyMz (M=Li, Na, Mg): Synthesis, structure and some properties

Abstract A new concept to prepare Maximally Disordered – High Entropy Intermetallic Phases (MD-HEIP) with the general formula of Gd1-xLaxSn2-ySbyMz (M = Li, Na, Mg) based on two mechanisms of substitution and insertion is proposed. As a result of the substitution of Gd by La and Sn by Sb in the binary GdSn2 compound, a maximally disordered (MD) phase of Gd1-xLaxSn2-ySby was formed. The formation of Gd1-xLaxSn2-ySbyLiz and Gd1-xLaxSn2-ySbyMgz HD-HEIP phases as the result of additionally inserting Li/Mg into tetragonal antiprismatic voids is observed during the electrochemical lithiation and magnesiation, respectively. The Gd1-xLaxSn2-ySbyNaz phase was formed by partial substitution of Sn atoms by Na atoms. The Gd1-xLaxSn2-ySby and Gd1-xLaxSn2-ySbyMz phases have been studied by XRD, SEM, EPMA, Sn Mossbauer spectroscopy, 7Li NMR, electrochemical techniques, magnetization and heat capacity measurements. The electrochemical studies of cyclic characteristics show that the MD-HEIP electrodes are rapidly activated (5–6 cycles) and continue to work steadily, almost without losing capacity. The MD phases of Gd1-xLaxSn2-ySby and Gd1-xLaxSn2-ySbyNaz show very similar behaviour of physical properties. Both MD phases of Gd1-xLaxSn2-ySby and Gd1-xLaxSn2-ySbyNaz have a comparably strong mean field antiferromagnetic coupling (θ around −41 K) and show typical Currie-Weiss paramagnetic behaviour of localized Gd magnetic moments down to ∼20 K. Both MD – HEIP Gd1-xLaxSn2-ySbyMz (M = Li and Mg) samples show a lowered antiferromagnetic mean field coupling (θ around −13 K) compared to MD phases.

Cathecol and Naphtol Groups in Salphen-Type Schiff Bases for the Preparation of Polynuclear Complexes.

In this paper, we show a strategy to modify salphen-type Schiff base ligands with naphtol (SYML1) and pyrocathecol (2,3-dihydroxyphenyl) groups (SYML2), or a combination of both (ASYML). Each of these ligands can be used to obtain polynuclear metal complexes following two different strategies. One relies on using metals that are either too large for the N2O2 cavity or not fond of coordination number 4 and the other one relies on forcing the polynuclear species by adding functional groups to the hydroxybenzaldehayde in order to have extra coordination sites in the ligand. We report and characterize the mononuclear complexes SYML1-Cu and SYML1-Ce, along with the dinuclear complex SYML1-Fe and the tetranuclear species SYML2-Mn. The asymmetric ligand ASYML routinely hydrolyzes into the symmetric ligands in the reaction mixtures. SYML1-Fe displays a nearly linear Fe-O-Fe bridge with very strong antiferromagnetic coupling between the Fe(III) ions.

First-principles study of magnetism and phase stabilities of V2 based antiferromagnetic Heusler alloys

We investigate the phase stability and magnetism of V2 based antiferromagnetic semiconductors by first-principles calculations. We first analyze the phase stability of the designed alloys by calculating the convex hull and find that keeping Al atoms in the Z sites is crucial to guarantee the stability against the segregation. The V2YAl (Y=V, Nb, and Ta) systems have relatively small hull distances and Néel temperatures higher than 1000 K are evaluated. The strong antiferromagnetic coupling between V atoms is rapidly decreasing with increasing the number of electrons due to the appearance of ferromagnetic double-exchange interaction. By applying a uniaxial strain to induce tetragonal distortion, a relatively large magneto-crystalline anisotropy energy is obtained for V2TaAl. It is claimed that V2YAl are thought to be good candidates for antiferromagnetic spintronics including gate-tunable magnetic properties.

(FeCoB/Ru/FeCoB)/ZnO]n superlattice multilayer: A real optical mode ferromagnetic resonance thick-film

A pure optical mode (OM) resonance with ultrahigh resonance frequency (frO) and permeability μ at zero bias field was observed in 50-nm FeCoB/Ru/FeCoB sandwich trilayers due to the presence of strong antiferromagnetic interlayer exchange coupling. However, the necessary thickness for creating practical microwave devices cannot be readily achieved by increasing the FeCoB layer thickness or stacking FeCoB/Ru units due to dramatically deteriorated high-frequency performance. In this study, several 50-nm FeCoB/Ru/FeCoB OM units were stacked to form a superlattice structure, with 10-nm ZnO insulator spacers separating the units. It is interesting that the superlattice multilayers not only retain excellent high-frequency OM resonance performance comparable to the single OM unit but also increase the effective magnetic film thickness by a factor of 5. This can be attributed to the positive superposition of the almost identical OM units as well as the effective decoupling between them by thick ZnO spacers. This study provides a promising way to fabricate thicker films while still maintaining excellent OM resonance performance.

Spin reorientation by Ni doping in Cu1−xNixCr2O4 spinels with x = 0 and 0.1, and evidence for canted magnetic Cr order above the onset of a ferromagnetic Cu

In ferrimagnetic spinels AB2O4 the magnetic structure is strongly influenced by lattice distortions, geometric frustration and the electronic properties of the cations at the A and B sites. Here, we report a comprehensive study on the temperature dependence of the magnetic structure of CuCr2O4 and Cu0.9Ni0.1Cr2O4 using neutron diffraction. CuCr2O4 undergoes a first continuous magnetic transition around 155 K into a canted long-range spin order on the Cr sublattice established by an antiferromagnetic and a ferromagnetic mode. Below 130 K a second transition occurs into a ferromagnetic order on the Cu sublattice resulting in a ferrimagnetic spin arrangement. Correlations between the appearance of magnetic modes and changes in the lattice geometry at different temperatures are discussed giving insight to magnetoelastic coupling. The occurrence of a ferromagnetic Cr mode above 130 K questions the common interpretation that a strong antiferromagnetic coupling between A and B spins in ferrimagnetic AB2O4 spinels is responsible for spin canting. From our neutron diffraction measurements of Cu1−xNixCr2O4 we identify a spin reorientation for the ferromagnetic modes with a nickel content between x = 0 and 0.1.

Insensitivity of Magnetic Coupling to Ligand Substitution in a Series of Tetraoxolene Radical-Bridged Fe2 Complexes.

The elucidation of magnetostructural correlations between bridging ligand substitution and strength of magnetic coupling is essential to the development of high-temperature molecule-based magnetic materials. Toward this end, we report the series of tetraoxolene-bridged FeII2 complexes [(Me3TPyA)2Fe2(RL)]n+ (Me3TPyA = tris(6-methyl-2-pyridylmethyl)amine; n = 2: OMeLH2 = 3,6-dimethoxy-2,5-dihydroxo-1,4-benzoquinone, ClLH2 = 3,6-dichloro-2,5-dihydroxo-1,4-benzoquinone, Na2[NO2L] = sodium 3,6-dinitro-2,5-dihydroxo-1,4-benzoquinone; n = 4: SMe2L = 3,6-bis(dimethylsulfonium)-2,5-dihydroxo-1,4-benzoquinone diylide) and their one-electron-reduced analogues. Variable-temperature dc magnetic susceptibility data reveal the presence of weak ferromagnetic superexchange between FeII centers in the oxidized species, with exchange constants of J = +1.2(2) (R = OMe, Cl) and +0.3(1) (R = NO2, SMe2) cm-1. In contrast, X-ray diffraction, cyclic voltammetry, and Mössbauer spectroscopy establish a ligand-centered radical in the reduced complexes. Magnetic measurements for the radical-bridged species reveal the presence of strong antiferromagnetic metal-radical coupling, with J = -57(10), -60(7), -58(6), and -65(8) cm-1 for R = OMe, Cl, NO2, and SMe2, respectively. The minimal effects of substituents in the 3- and 6-positions of RLx-• on the magnetic coupling strength is understood through electronic structure calculations, which show negligible spin density on the substituents and associated C atoms of the ring. Finally, the radical-bridged complexes are single-molecule magnets, with relaxation barriers of Ueff = 50(1), 41(1), 38(1), and 33(1) cm-1 for R = OMe, Cl, NO2, and SMe2, respectively. Taken together, these results provide the first examination of how bridging ligand substitution influences magnetic coupling in semiquinoid-bridged compounds, and they establish design criteria for the synthesis of semiquinoid-based molecules and materials.

Spiral order from orientationally correlated random bonds in classical XY models

We discuss the stability of ferromagnetic long-range order in three-dimensional classical XY ferromagnets upon substitution of a small subset of equally oriented bonds by impurity bonds, on which the ferromagnetic exchange J_perp > 0 is replaced by a strong antiferromagnetic coupling J_imp < 0. In the presence of a single impurity bond, once the absolute value of the frustrating coupling J_imp < 0 exceeds a threshold J_c > 0, the ground state becomes two-fold degenerate, corresponding to either clockwise or anticlockwise canting of the spins in the vicinity of the impurity bond. In the presence of a small concentration of impurity bonds, the effective low-energy Hamiltonian is that of Ising variables encoding the sense of rotation of the local canting around the impurities. Those degrees of freedom interact through a dipolar interaction mediated by spin waves. A ferromagnetic Ising ground state indicates the instability of the XY ferromagnet towards a spiral state with a wave vector proportional to the concentration of impurity bonds. To analyze under which circumstances such a ground state arises, we study first impurities forming superlattices. For a subclass of those, we can rigorously establish the existence of spiral order. For another class of superlattices, the Ising variables order ferromagnetically in planes perpendicular to the orientation of impurity bonds, but antiferromagnetically parallel to it, which results in a fan-like XY ground state. Second, we consider the case when the impurity bonds are randomly distributed on the three-dimensional host lattice according to a Poisson process. We show the phenomenon of spiral order by disorder with an ordering wave vector proportional to the impurity concentration. The analytical predictions are confirmed by Monte Carlo simulations and are relevant for magnetic materials such as YBaCuFeO_5.

Magnetocaloric effect in ercu-based metallic glass composite

In order to reduce the worsen effects of strong antiferromagnetic coupling between Er and Fe, Co, Ni elements on the magnetocaloric effect of Er based amorphous alloys, an Er45Cu45Al10 metallic glass composite is fabricated and its magnetocaloric effect is studied. The alloy exhibits large magnetic entropy change (14.6 Jkg−1K−1) and high refrigerant capacity (330 Jkg−1) under a magnetic field of 5 T, which is a promising candidate for a magnetic refrigerant in helium liquefaction temperature range. It is intriguing that the entropy change normalized to the rare earth elements for this Er45Cu45Al10 alloy is much higher than other Er-based metallic glasses, which is attributed to the weaker antiferromagnetic interactions between Er and Cu. These results are helpful for designing advanced rare earth-based magnetocaloric materials.

Quinoxaline radical-bridged transition metal complexes with very strong antiferromagnetic coupling.

A new family of radical-bridged compounds, (Cp*2Co)[M2Cl4(dpq)] (M = Fe (1), Co (2), Zn (3)), (dpq = 2,3-di(2-pyridyl)-quinoxaline) is reported. Magnetic studies, DFT and ab initio calculations reveal strong antiferromagnetic metal-radical interactions with coupling constants of J = -213.1 and -218.8 cm-1 for 1 and 2, respectively.

Two New Copper(Ii) Binuclear Complexes with Azo Functionalized 2-[(E)-(Pyridine-2yl-Hydrazono)Methyl]Phenol: Characterization, Molecular Structures, Quantum Chemical Calculations, Cryomagnetic Properties and Catalytic Activity

The Schiff base is synthesized by the reaction of 2-hydrazinopyridine and salicylaldehyde. The copper(II) binuclear complexes [Cu 2 (µ 2 -ClO 4 )(L) 2 (H 2 O) 2 ](ClO 4 )·H 2 O (1) and [Cu 2 (µ 2 -pyrazine)(L) 2 ](ClO 4 ) 2 (2) with 2-[(E)-(pyridine-2yl-hydrazono)methyl]phenol (HL), were synthesized and characterized using various physicochemical techniques. The molecular structures of both binuclear complexes were evaluated by single-crystal X-ray analysis. Analysis of the supramolecular synthons and their effect on crystal packing is conferred in the context of crystal engineering. The electron paramagnetic spectra are reported as well. The electrochemical behavior of both complexes was explored using cyclic voltammetry (CV) and differential pulse voltammetry (DPV) techniques. The electronic and spectral properties are described by quantum chemical calculations (TD and DFT).The cryomagnetic investigation (2-300 K) reveal antiferromagnetic exchange coupling between two copper(II) centres of different strength: J CuCu = -21.6 and J CuCu = -6.8 cm -1 for 1 and 2 , respectively. The strong antiferromagnetic coupling between the copper centers found in 1 could be explained not only by magnetic exchange through hydrogen bonds but also through the π-π stacking of the Schiff base ligands. Both binuclear complexes exhibit catalytic activity toward the dismutation of superoxide anion at physiological pH. Although the activity in both complexes is lower than the native enzyme, they have potential as antioxidant SOD model for pharmaceutical applications.