A 48-Metal Cluster Exhibiting a Large Magnetocaloric Effect

The [enPd(II)]2+ (en = ethylenediamine) unit has emerged as a versatile building block in molecular self-assembly. In particular, the 90 degrees coordination angle of the metal has been judiciously used in the design of new discrete two- and three-dimensional structures. Our last 15 years of work with the Pd(II)-cornered unit is summarized in this Account, from the spontaneous formation of a Pd4 square metal complex to a family of architectures such as cages, bowls, boxes, tubes, catenanes, and spheres.

Molecular nanomagnets are considered valid candidates for magnetic refrigeration at low temperatures. Designing these materials for enhanced cooling requires the control and optimization of the quantum properties at the molecular level, in particular: spin ground state, magnetic anisotropy, and presence of low-lying excited spin states. Herein, we present the theoretical framework together with a critical review of recent results, and perspectives for future developments.