Anion-Templated Assembly and Magnetocaloric Properties of a Nanoscale {Gd38} Cage versus a {Gd48} Barrel

The comprehensive study reported herein provides compelling evidence that anion templates are the main driving force in the formation of two novel nanoscale lanthanide hydroxide clusters, {Gd-38(ClO4)(6)} (1) and {Gd48Cl2(NO3)} (2), characterized by single-crystal X-ray crystallography, infrared spectroscopy, and magnetic measurements. {Gd-38(ClO4)(6)}, encapsulating six ClO4- ions, features a cage core composed of twelve vertex-sharing {Gd-4} tetrahedrons and one Gd center dot center dot center dot Gd pillar. When Cl- and NO3- were incorporated in the reaction instead of ClO4-, {Gd48Cl2(NO3)} is obtained with a barrel shape constituted by twelve vertex-sharing {Gd-4} tetrahedrons and six {Gd-5} pyramids. What is more, the cage-like {Gd-38} can be dynamically converted into the barrel-shaped {Gd-48} upon Cl- and NO3- stimulus. To our knowledge, it is the first time that the linear M-O-M' fashion and the unique mu(8)-ClO4- mode have been crystallized in pure lanthanide complex, and complex 2 represents the largest gadolinium cluster. Both of the complexes display large magnetocaloric effect in units of J kg(-1)K(-1) and mJ cm(-3) K-1 on account of the weak antiferromagnetic exchange, the high N-Gd/M-W ratio (magnetic density), and the relatively compact crystal lattice (mass density).