Tetranuclear MnII, CoII, CuII and ZnII grid complexes of an unsymmetrical ditopic ligand: synthesis, structure, redox and magnetic properties

Three Gd-based magnetic refrigerant materials with high magnetic entropy: From di-nuclearity to hexa-nuclearity to octa-nuclearity

Magnetocaloric effect (MCE) is one of the most promising features of molecular-based magnetic materials. We reported three Gd-based magnetic refrigerant materials, namely, Gd₂(L)(NO₃)(H₂O)‧CH₃CN‧H₂O (1, H₂L = (Z)-N-[(1E)-(2-hydroxy-3-methphenyl)methylidene]pyrazine-2-carbohydrazonic acid), {Gd₆(L)₆(CO₃)₂(CH₃OH)₂(H₂O)₃Cl}Cl‧4CH₃CN (2), and Gd₈(L)₈(CO₃)₄(H₂O)₈‧2H₂O (3). Complex 1 contains two Gd^III ions linked by two η²:η¹:η¹:η¹:μ₂-L^2- ligands, which are seven-coordinated in a capped trigonal prism, and complex 2 possesses six Gd^III ions, contributing to a triangular prism configuration. For complex 3, eight Gd^III ions form a distorted cube arrangement. Moreover, the large values of magnetic entropy in the three complexes prove to be excellent candidates as cryogenic magnetic coolants.

Recent developments in supramolecular complexes of azabenzenes containing one to four N atoms: synthetic strategies, structures, and magnetic properties

For the last couple of decades, azabenzene-based ligands have drawn much attention from inorganic chemists due to their ability to coordinate with different metal ions to form supramolecular clusters. These azabenzenes are weak σ donors and strong π acceptors and electron-deficient. Metallogrid complexes and non-grid oligomers are well-defined supramolecular clusters, formed by appropriate chelating ligands, and can show interesting optical, magnetic, and electronic properties. Self-assembly of [n × n] metallogrid complexes is dominated by the entropic factor while the formation of oligonuclear metal ion complexes is dominated by other effects like CFSE, electrostatic factors, ligand conformational characters, etc. Herein, the present article gives an overview of six-membered heterocyclic azine-based ligands and their potential for different metal ions to form polynuclear complexes. Moreover, their temperature-dependent magnetic properties and SCO phenomena are well described and tabulated.

Magnetic Phase Transitions in a Ni4 O4 -Cubane-Based Metal-Organic Framework

An unprecedented spin cluster‐based network architecture {[Ni^II₂(pdaa)(OH)₂(H₂O)]_n (H₂pdaa=1,4‐phenylene diacetic acid)}, comprising 1D linear chains of Ni^II ions crosslinked via Ni₄O₄ cubanes, forms under hydrothermal conditions; this 3D coordination network exhibits magnetic ordering at 23.9 K as well as a second magnetic ordering process at 2.8 K likely associated with a structural phase transition.