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, Gd(2)(L)(NO(3))(H(2)O)‧CH(3)CN‧H(2)O (1, H(2)L = (Z)-N-[(1E)-(2-hydroxy-3-methphenyl)methylidene]pyrazine-2-carbohydrazonic acid), {Gd(6)(L)(6)(CO(3))(2)(CH(3)OH)(2)(H(2)O)(3)Cl}Cl‧4CH(3)CN (2), and Gd(8)(L)(8)(CO(3))(4)(H(2)O)(8)‧2H(2)O (3). Complex 1 contains two Gd(III) ions linked by two η (2):η (1):η (1):η (1):μ (2)-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.