Heteropoly acids (HPAs), especially the Keggin-type, as multi-electron oxidants or strong acids have attracted much attention in the last three decades [1-3]. Their acid strength is mostly higher than many mineral or conventional solid acids. Supported HPAs catalysts are important since they can easily be recovered from reaction mixtures and reused. Nanoparticles have also come into view as high surface area heterogeneous catalysts and catalyst supports; however, they are frequently difficult to be removed from the product mixture. Recent studies show that magnetic nanoparticles are excellent supports for various catalysts and can easily be separated and recycled from the products by an external magnet.In this article, we report the synthesis and characterization of diamine modified silica coated magnetite-polyoxometalate nanoparticles as a novel nanomagnetically-recoverable catalyst and evaluate its catalytic activity in the synthesis of xanthene derivatives.
