Effect of diamagnetic Zn(II) ions on the SMM properties of a series of trinuclear ZnDy2 and tetranuclear Zn2Dy2 (LnIII = Dy, Tb, Gd) complexes: combined experimental and theoretical studies

To study the effect of diamagnetic ions on magnetic interactions, utilizing a compartmental ligand (Z)-2-(hydroxymethyl)-4-methyl-6-((quinolin-8-ylimino)methyl)phenol (LH2), two different series of ZnII-LnIII complexes, namely the trinuclear series of [DyZn2(L)2(μ2-OAc)2(CH3OH)2]·NO3·MeOH (1), [TbZn2(L)2(μ2-OAc)2(CH3OH)2]·NO3·5MeOH·H2O (2), and [GdZn2(L)2(μ2-OAc)2(CH3OH)2]·NO3·MeOH·CHCl3 (3) and the tetranuclear series of [Dy2Zn2(LH)4(NO3)4(μ2OAc)]·NO3·MeOH·H2O (4), [Tb2Zn2(LH)4(NO3)4(μ2-OAc)]·NO3·MeOH·2H2O (5), and [Gd2Zn2(LH)4(NO3)4(μ2-OAc)]·NO3·MeOH·2H2O (6), were synthesized. Trinuclear ZnII-LnIII complexes 1-3 consist of one LnIII ion sandwiched between two peripheral ZnII ions forming a bent type ZnII-DyIII-ZnII array with an angle of 110.64°. Tetranuclear ZnII-LnIII complexes 4-6 are basically a combination of two dinuclear moieties of [LnZn(LH)2(NO3)2]+ connected by one bidentate bridging acetate ion in μ2-OAc coordination mode. The detailed magnetic analysis reveals that complexes 1 and 4 are single molecule magnets having energy barriers of 34.98 K and 46.71 K with relaxation times (τ0) of 5.05 × 10-4 s and 5.24 × 10-4 s, respectively. Ab initio calculations were employed to analyze the magnetic anisotropy and magnetic exchange interaction between the ZnII and LnIII centers with the aim of gaining better insights into the magnetic dynamics of complexes 1-6.

Constructing an unprecedented {MnII38} matryoshka doll with a [Mn18(CO3)9] inorganic core and magnetocaloric effect

An unprecedented inner [Mn₁₈(CO₃)₉] inorganic core and [Mn₂₀] metal-organic periphery compose a high-nuclearity homometallic single-valent {Mn^II₃₈} molecular aggregate with a [Mn₆] ⊂ [Mn₁₂] ⊂ [Mn₈] ⊂ [Mn₁₂] matryoshka doll-like skeleton that displays a significant magnetocaloric effect (MCE).

Hierarchical Construction and Magnetic Difference of {Co12M12} (M = Co2+/Cd2+) Aggregates from {Co14} Cluster-Based Precursors in the Presence of Homo/Heterometal Salts

The controllable construction and function expansion of some sophisticated aggregations represent a current hot topic in scientific research. In this paper, using a prefabricated {Co₁₄} cluster as a synthetic precursor, a homometallic {Co₂₄} and a heterometallic {Co₁₂Cd₁₂} giant cluster possessing similar dual-[M₁₂] (M = Co/Cd) skeletons was prepared by reacting the precursor with excess CoCl₂ and Cd(OAc)₂ salts, respectively. The detailed structural information on {Co₂₄} and {Co₁₂Cd₁₂} was characterized by single-crystal X-ray diffraction and further analyzed by X-ray photoelectron spectroscopy, inductively coupled plasma-mass spectroscopy, and scanning electron microscopy with energy dispersive X-ray (EDX) spectroscopy in the solid state. Compared to the {Co₁₄} precursor, magnetic difference revealed that spin-canting and magnetic ordering had been enhanced in {Co₂₄} and suppressed in {Co₁₂Cd₁₂} when dotted with diamagnetic Cd²⁺ ions.

Structural characterization and magnetic property studies of a mixed-valence {CoIIICo} complex with a μ4-oxo tetrahedral {Co} motif

We have synthesized and structurally characterized a new mixed valence pentanuclear Co complex, bearing a rare μ4-O-tetrahedral CoII4 unit, by employing a pyridine-like Schiff base ligand. We have performed DC magnetic susceptibility and magnetization measurements over polycrystalline samples and chemical quantum computations in order to understand the exchange interaction pattern within Co(ii) sites and ground state magnetic anisotropy. This new complex shows an overall antiferromagnetic exchange interaction whose strength strongly depends on the local symmetry of Co(ii) sites. Also, local ion magnetic anisotropy reveals a strongly axial behaviour with the lowest Kramers doublet (KD) at each Co(ii) ion sufficiently isolated from excited states at low temperatures. Two Co(ii) sites show tetrahedral symmetry and the spin only formalism including axial zero-field splitting (ZFS) term properly described them; on the other hand, the other two Co(ii) sites have distorted octahedral and square base pyramidal coordination spheres, and a strong orbital contribution leads to a failure of the spin only formalism. A model of four Seff = 1/2 exchange interacting sites is necessary in order to account for low temperature magnetization behaviour. In view of the strongly anisotropic KD states, the exchange interactions are forced to be modelled as anisotropic ones. Overall, experimental data and quantum chemical computations are in good agreement, supporting the proposed model for magnetic behaviour.

2D lanthanide coordination polymers constructed from a semi-rigid tricarboxylic acid ligand: crystal structure, luminescence sensing and color tuning

Three lanthanide polymers {[Ln(TMCA)(DEF)(H₂O)]·(CH₃CN)}_n (Ln = Eu 1; Tb 2; Gd 3; H₃TMCA = 4′,4′,4′-[(trimethylamino)]-tris[(1,1′-biphenyl)-2-carboxylic acid]) were synthesized under solvothermal conditions.

Tetrahedral μ4-chloride and in situ generated octahedral μ6-sulfide templating Co8 complexes with different distortions of the cube

Herein two unprecedented octanuclear Co8 clusters are presented, [Cl@Co8 (TEOA)4(CH3CN)Cl3] (1) and [S@Co8(DEOA)6(NCS)2] (2) (H3TEOA = triethanolamine, H2DEOA = diethanolamine), in which tetrahedral μ4-chloride and in situ generated octahedral μ6-sulfide are used as templates. In spite of them being derivatives of cubes, eight Co atoms in 1 consist of two co-centered tetrahedra of different sizes, whereas in 2 they appear as a rhombohedron formed via elongating a cube along the C3-axis direction. Strong intra-cluster antiferromagnetic interactions were found.

Two new MOFs based on 5-((4-carboxypyridin-2-yl)oxy) isophthalic acid displaying unique selective CO2 gas adsorption and magnetic properties

The reaction of Cu(ii)/Co(ii) with a N-heterocyclic carboxylate ligand produced two new MOFs with different topologies. The Cu-MOF showed selective adsorption for CO₂ over CH₄, and the antiferromagnetic properties existed in the two MOFs.

Four new metal–organic frameworks based on diverse secondary building units: sensing and magnetic properties

Four new metal–organic frameworks based on diverse secondary building units were assembled and 1 showed high selectivity in the detection of CrO₄²⁻, Cr₂O₇²⁻, MnO₄⁻ and Fe³⁺.