Metallic-based magnetic switches under confinement

Bistability is undoubtedly one of the most desired properties when designing new technological materials. Molecular magnets, including single-molecule and single-ion magnets, exhibit slow relaxation of their magnetization in addition to magnetic bistability, whereas spin crossover materials are just bistable switches that can be either in low-spin or high-spin depending on their history. These materials have received a great deal of attention because of their potential applications in ultra-high-density information storage, where each molecule can be used as a magnetic bit of information, and quantum computing, by taking advantage of long coherence intervals. For harnessing the magnetic bistability of these appealing switches, the controlled organization in different dimensionality architectures (essential for read-and-write processes) is required. However, it has proven to be a challenging task given that their chemical integrity and unique magnetic properties must be preserved during nanostructuration. This review highlights recent advances on the confinement of guest magnetic switches within host nanocontainers, such as the void cages of fullerenes and the internal cavities of carbon nanotubes and metal-organic frameworks, yielding zero-, one- and three-dimensional hybrid nanostructures. Detailed discussion of synthetic challenges, confinement methodologies and effects on the properties of the guest magnetic switches upon encapsulation is given here. In spite of the vibrant research in recent years, significant challenges lie ahead. Although spins confined within host nanocontainers can be protected from the environment and manipulated externally, control of their molecular distances has not yet been achieved. A discussion of current challenges and future perspectives in the emerging field of nanostructuration is also presented here.