Intercalation of [Fe8(μ3-O)2(μ2-OH)12(tacn)6]8+ single molecule magnets in saponite clay

We have contacted Na-saponite with aqueous solutions containing a well-defined iron polycation with structuring ligands [Fe8(μ3-O)2(μ2-OH2)12(tacn)6]8+, which is known as a promising candidate for molecular magnets. When the resulting suspensions were activated with either microwaves or ultrasound, macroscopic-level characterization of the solid phases obtained after centrifugation (elemental analysis, surface area, XRD) suggested the intercalation of stoichiometrically intact polycations in the interlayer space by cation exchange. Furthermore, 57Fe Mössbauer spectroscopy and Fe K-edge EXAFS are compatible with a conservation of the structure of the polycations inorganic core: connectivity seems to be maintained, while the polycations must be somewhat flattened by strain due to intercalation. Magnetization curves also appear compatible with a conservation of the polycation nuclearity, although experiments with a magnetically clean clay sample are necessary to confirm this point.