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,
though surface immobilization generally diminishes their magnetic
performance. Here, we show how tailored Lewis acidic Al(III) sites
on a silica surface enable generation of a material with SMM characteristics
via chemisorption of (Cpttt)2DyCl ((Cpttt)−= 1,2,4-tri(tert-butyl)-cyclopentadienide).
Detailed studies of this system and 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 up to 8 K and an effective energy barrier
(Ueff) of 449 cm–1,
the highest reported thus far for a supported SMM.