Three-Dimensional 3d−4f Heterometallic Coordination Polymers: Synthesis, Structures, and Magnetic Properties

Cu(II)-Ln(III) (Ln = Gd, Tb and Dy) complexes of an unsymmetrical N2O3 donor ligand: field induced SMM behaviour of Cu(II)-Tb(III) complexes

Three new hetero-metallic CuII-LnIII complexes [(CuL)Gd(NO3)3(CH3OH)]n (1), [(CuL)Tb(NO3)3(H2O)]·[CuL] (2) and [(CuL)Dy(NO3)3(H2O)]·[CuL] (3) have been synthesized using a mono-nuclear Cu(II) complex, [CuL], of an unsymmetrically di-condensed N2O3 donor Schiff base ligand, N-(3-methoxysalicylidene)-N-(salicylidene)-1,2-ethylenediamine (H2L). Single crystal X-ray crystallography revealed that complex 1 is a nitrate bridged 1D chain of dinuclear Cu(II)-Gd(III) units whereas in 2 and 3, the dinuclear Cu(II)-Ln(III) units are co-crystallized with a [CuL] unit. The Ln(III) centers are nine coordinated with the geometry of a spherical capped square antiprism for Gd and spherical tricapped trigonal prism for Tb and Dy. The geometry of the Cu(II) center is distorted octahedral for complex 1 and distorted square planar for complexes 2 and 3. Temperature-dependent molar magnetic susceptibility measurements in 1-3 revealed the presence of overall ferromagnetic coupling between the Cu(II) and Ln(III) centers. Notably, field induced single-molecule magnet behavior was witnessed in the Tb(III) derivative (2). The ab initio calculations indicated that upon application of an external magnetic field, the tunneling in the ground state of complex 2 gets reduced and thereby field-induced SMM behaviour is observed. Besides, in the case of complex 1, BS-DFT calculations were carried out to gain further insights into the magnetic exchange coupling interactions between the Cu(II) and Gd(III) centers.

Field-induced slow magnetic relaxation in mixed valence di- and tri-nuclear CoII-CoIII complexes

Two novel mixed valence Co^II-Co^III complexes, namely [Co^IICo^III(L1)(ab)(mb)₂(H₂O)]·dmf (1) and [CoCo^II(L2)₄(H₂O)₄]·2H₂O (2) [H₂L1 = (E)-2-((1-hydroxybutan-2-ylimino)methyl)-6-methoxyphenol, ab = 2-amino-butan-1-ol anion, mb = p-methyl benzoate, H₂L2 = 3-((2-hydroxy-3-methoxy-benzylidene)-amino)-propionic acid, and dmf = N,N-dimethyl-formamide], were synthesized and characterized by single crystal X-ray diffraction and magnetic studies at low temperature. The structure determination reveals that both complexes belong to the monoclinic system with P21/c (1) and I2/a (2) space groups. Complex 1 is a dinuclear Co^IIICo^II compound with distorted octahedral cobalt centers showing different coordination environments. In 2, a bent trinuclear CoCo^II complex, the coordination environments around the two terminal Co^III sites are alike, whereas they are different in the central Co^II ion. Alternating current/direct current (ac/dc) magnetic studies revealed that both complexes show field-induced slow magnetic relaxation. The dc magnetic susceptibility and magnetization data were analyzed with the following Hamiltonianwhere D and E are the axial and rhombic zero-field splitting (zfs) parameters, respectively, and a good agreement between experimental and simulated results was found using the parameters g_⊥ = 2.585, g_∥ = 2.437, D = +98.1 cm^-1, E/D = 0.008 and F = 8.2× 10^-5 for 1 and g_⊥ = 2.580, g_∥ = 2.580, D = +55.4 cm^-1, and E/D = 0.000 for 2.

SMM behaviour of heterometallic dinuclear CuIILnIII (Ln = Tb and Dy) complexes derived from N2O3 donor unsymmetrical ligands

Four heterometallic dinuclear Cu^IILn^III (Ln = Tb and Dy) complexes derived from two different N₂O₃ donor unsymmetrical Schiff base ligands exhibit SMM behaviour.

Efficient pure white light emission based on a three-component La:Eu,Tb-doped luminescent lanthanide metal–organic framework

A three-component Eu and Tb-doped La complex based on a semirigid tricarboxylate ligand is successfully constructed with high-efficiency white light emission (Φ = 11.22% at 345 nm).

Bis-phenoxido and bis-acetato bridged heteronuclear {Co(III)Dy(III)} single molecule magnets with two slow relaxation branches

Two bis-μ-phenoxido-bis-μ-acetato heterobimetallic {Co(III)Dy(III)} complexes and , formulated as [Co(III)Dy(III)L(μ-OAc)2(NO3)2] derived from the comparable hexadentate Schiff bases N,N'-ethylenebis(3-ethoxysalicylaldimine) and N,N'-ethylenebis(3-methoxysalicylaldimine) were synthesized and X-ray structure analysis confirms their nearly identical structures. These are the first examples of bis(μ-phenoxido)-bis(μ-carboxylato) {Co(III)Dy(III)} systems. The AC susceptibility measurements show that both complexes exhibit a field-induced slow magnetic relaxation with two relaxation branches. While the high-frequency process spans the usual range of the relaxation time for analogous single molecule magnets (τ0 ∼ 10(-7) s), the low-frequency branch is as slow as τ ∼ 0.1 s at T = 1.9 K and B = 0.2 T.

Syntheses, structures, and properties of a series of novel high-nuclear 3d–4f clusters with mixed amino acids as ligands: {Ln6Cu24}(Ln = Gd, Tb, Pr and Sm)

The first examples of high-nuclear 3d–4f heterometallic clusters {Ln₆Cu₂₄}(Ln = Gd, Tb, Pr and Sm) with mixed amino acid ligands are reported.

Hydrothermal synthesis, X-ray structure and DFT and magnetic studies of a (H2SiW12O40)2− based one-dimensional linear coordination polymer

In this paper, we report the synthesis and characterization of a novel POM-based inorganic–organic hybrid with an in situ transformation of pyridine-2,3-dicarboxylic acid into nicotinic acid and 2-hydroxynicotinic acid under hydrothermal conditions.

Syntheses, structures, photoluminescence and photocatalysis of chiral 3D Cd(ii) frameworks from achiral mixed flexible ligands by spontaneous resolution

Two three-interpenetrating chiral cadmium MOF enantiomers with good photocatalytic activities for degradation of dyes were constructed from achiral flexible ligands.

Two dimensional porous 3d–4f heterometallic coordination polymers constructed by pyridine-2,3-dicarboxylic acid

Four porous Co^IIILn^III 3d–4f heterometallic coordination polymers constructed by the pydcH₂ ligand were hydrothermally synthesized and characterized. The adsorption and catalytic properties of compound Co^IIIDy^III were investigated.

Temperature-controlled polymorphism of chiral CuII–LnIII dinuclear complexes exhibiting slow magnetic relaxation

A family of chiral Cu–Ln dinuclear complexes with two different space groups has been constructed. The temperature-controlled reversible conversion from one chiral single-crystal to another chiral single-crystal with slow magnetic relaxation has been achieved.

Ln–Cd heterometal organic–inorganic hybrid materials based on diverse Ln–Cd oxo-cluster chains: syntheses, structures and visible luminescence

Two types of luminescent Ln–Cd heterometal complexes, I and II, based on diverse Ln–Cd oxo-clusters have been synthesized and characterized.

Four 2D Ln–Cd heterometal–organic coordination polymers based on tetranuclear Ln–Cd oxo-cluster with highly selective luminescent sensing of organic molecules and metal cations

Two series of 2D-layered Ln–Cd heterometal–organic complexes based on tetranuclear [Ln₂Cd₂] oxo-clusters with selective luminescent sensing have been synthesized.

XPS-Characterization of Heterometallic Coordination Compounds with Optically Active Ligands

The heterometallic optical complexes [Cu2Co(S,S(+)cpse)3(H2O)3]·4H2O (1) and [Cu2Ni(S,S(+)cpse)3(H2O)3]·10H2O (2) were obtained from the mononuclear copper(II) compound by the addition of nickel(II) or cobalt(II) chlorides, where (H2cpse) is the acetyl amino alcohol derivative N-[2-hydroxy-1(R)-methyl-2(R)-phenylethyl]-N-methylglycine. In comparison with the homotrinuclear copper(II) compound [Cu3(S,S(+)cpse)3(H2O)3]·8H2O reported previously, the substitution of a copper(II) atom by one cobalt(II) ion gave place to a heterotrinuclear compound1, which presents ferromagnetic-antiferromagnetic behaviour. When substituting a copper(II) by a nickel(II) ion, the trinuclear compound2showed an antiferromagnetic coupling. The magnetic behaviour of the heterotrinuclear compounds is driven by the nature of the metal ion which was introduced in the copper(II) triangular array. The ligand and its coordination compounds were characterized by IR, UV-Vis-NIR. Their chemical was confirmed by photoelectron spectroscopy (XPS).