Molecular Lanthanide Switches for Magnetism and Photoluminescence

Solvation of [(CNT)Ln(η8 -COT)] (Ln=La, Ce, Nd, Tb, Er; CNT=cyclononatetraenyl, i.e., C9 H9- ; COT=cyclooctatetraendiid, i.e., C8 H82- ) complexes with tetrahydrofuran (THF) gives rise to neutral [(η4 -CNT)Ln(thf)2 (η8 -COT)] (Ln=La, Ce) and ionic [Ln(thf)x (η8 -COT)][CNT] (x=4 (Ce, Nd, Tb), 3 (Er)) species in a solid-to-solid transformation. Due to the severe distortion of the ligand sphere upon solvation, these species act as switchable luminophores and single-molecule magnets. The desolvation of the coordinated solvents can be triggered by applying a dynamic vacuum, as well as a temperature gradient stimulus. Raman spectroscopic investigations revealed fast and fully reversible solvation and desolvation processes. Moreover, we also show that a Nd:YAG laser can induce the necessary temperature gradient for a self-sufficient switching process of the Ce(III) analogue in a spatially resolved manner.