Tailored Lewis Acid Sites for High-Temperature Supported Single-Molecule Magnetism

Generating or even retaining slow magnetic relaxation in surface immobilized single-molecule magnets (SMMs) from promising molecular precursors remains a great challenge. Illustrative examples are organolanthanide compounds that show promising SMM properties in molecular systems while surface immobilization generally diminishes their magnetic performance. Here, we show how tailored Lewis acidic Al(III) sites on silica surface enable the synthesis of a material with SMM characteristics via chemisorption of (Cpttt)2DyCl ((Cpttt)= 1,2,4-tri(tert-butyl)- cyclopentadienide). Detailed studies of this system that also include its diamagnetic Y analogue indicate that the interaction of the metal chloride with surface Al sites results in a change of the coordination sphere around the metal center inducing for the dysprosium-containing material slow magnetic relaxation up to 51 K with hysteresis till 8 K and an effective energy barrier (Ueff) of 449 cm-1, the highest reported thus far for a supported SMM.