Silver Nanoparticles Engineered β-Cyclodextrin/γ-Fe2O3@ Hydroxyapatite Composite: Efficient, Green and Magnetically Retrievable Nanocatalyst for the Aqueous Reduction of Nitroarenes

Ag nanoparticles incorporated beta-cyclodextrin conjugated magnetic hydroxyapatite, gamma-Fe2O3@HAp-CD.Ag was conveniently synthesized via the grafting of beta-cyclodextrin moieties on the hydroxyapatite surface, followed by reacting of the nanocomposite, gamma-Fe2O3, with silver nitrate and then its reduction with sodium borohydride. The cavity of beta-cyclodextrin units as host material can stabilize the Ag nanoparticles (particles size: 12-14 nm) effectively and prevent their aggregation and separation from the surface. The nanocomposite obtained appears to have an organized structure, with a magnetic gamma-Fe2O3 core surrounded by a layer-structured coating shell. The structure and composition of the nanocomposite were confirmed by FT-IR, FE-SEM, TEM, TGA, XRD, EDS, BET, and VSM. This catalytic system selectively reduces the nitro group even in the presence of other sensitive functional groups in good to excellent yields (85-98%).The organometallic nanocatalyst was easily removed from solution using an external magnet and was successfully examined for five runs, with a slight loss of catalytic activity. Graphical Abstract [GRAPHICS] .