Intercalation of [Fe8(μ3-O)2(μ2-OH)12(tacn)6] 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.