Catalytically active, magnetically separable, and water-soluble FePt nanoparticles modified with cyclodextrin for aqueous hydrogenation reactions

A new multifunctional FePt nanoparticle (NP) exhibiting catalytic activity, magnetic properties, and water-compatibility, has been developed. The initial thermal decomposition of iron carbonyl (Fe(CO)₅), followed by reduction of platinum acetylacetonate (Pt(acac)₂) in the presence of oleic acid and oleylamine produced FePt NPs with Fe-rich core and Pt-rich shell. The hydrophobic NPs were subsequently treated with γ-cyclodextrin (γ-CD), which renders them water-dispersible rather than in organic solvents. Characterization by means of X-ray diffraction (XRD), transmission electron microscopy (TEM), superconducting quantum interface device (SQUID), and X-ray absorption fine structure (XAFS) measurements were performed. The FePt NPs capped with γ-CD (FePt-γ-CD) had a mean diameter of ca. 2.5 nm, which exhibited superparamagnetic behavior at 300 K with zero remanence and coercivity. The FePt-γ-CD was successfully employed as an efficient nanocatalyst for the aqueous hydrogenation reactions with the easy recovering from the reaction mixture by applying an external magnet. Moreover, the FePt-γ-CD prefers the hydrogenation of allyl alcohol over sterically hindered 3-cyclohexene-1-methanol in the competitive reaction due to the molecular recognition property imposed by the surface attached γ-CD.