Electro-activity and magnetic switching in lanthanide-based single-molecule magnets
The control of the single-molecule magnet (SMM) behaviour is highly challenging but crucial to design molecular materials suitable for potential applications in molecular devices. To switch the SMM behaviour, a plethora of external stimuli can be employed such as electro-activity, solvents, protonation, magnetic and electric fields, and light. All these stimuli induce structural modifications and thus, to some degree, changes in the electronic properties. Lanthanide ions are elements extremely sensitive to crystal field effects i.e. they are sensitive to any structural changes making them ideal candidates for the design of molecular switches. This article reviews both the pool of electro-active lanthanide SMMs and the various switching modes such as redox-, solvato-, photo- and proton-switching lanthanide SMM behaviours. These examples highlight the importance of inducing electronic distribution changes close to the lanthanide centre to reach a complete ON–OFF switching but also the preponderance of further structural changes and intermolecular interactions to modulate the magnetic properties. The present review should convince scientific communities that the use of lanthanide ions in the design of molecular switches is a promising strategy.