Shining new light on multifunctional lanthanide single-molecule magnets.

Single-molecule magnets (SMMs) are at the forefront of new technological advances in quantum information processing and spintronics. Despite the recent impressive breakthroughs in extending the magnetic blocking temperatures beyond liquid nitrogen temperatures, significant challenges await in terms of integrating and addressing such compounds in devices. With this ultimate goal in mind, the design of multifunctional SMMs not only allows to imbue molecules of interest with specific properties that would allow for in-situ monitoring of the SMM operation in real-time, but can also provide critical insights into our understanding of the magnetic behaviour. In this Review, we highlight how magnetism and luminescence can be harmoniously combined within single molecules in order to achieve these objectives. The key design principles to attain the simultaneous combination of photoluminescence and slow relaxation of the magnetization are discussed, keeping a keen eye on the future for how such molecules could be beneficial to emerging next-generation spintronics devices.