the immobilized ni(ii) species on thiourea functionalized copper ferrite: a reusable nanocatalyst for synthesis of biscoumarins under solvent-free conditions

In this study, nanoparticles of cufe2o4@sio2@ptms@tu@ni(ii) as the reusable magnetic catalyst were prepared. synthesis of the ni(ii)–cufe2o4 system was carried out through a five-step procedure including the preparation of cufe2o4 as the prime magnetic core, layering of silica, 3-chloropropyltrimethoxysilane and thiourea and finally the immobilization of ni(oac)2·4h2o. the prepared nanocomposite system was then characterized using ft-ir, sem, edx, xrd, vsm, icp-oes and tga/dsc analyses. catalytic activity of cufe2o4@sio2@ptms@tu@ni(ii) was further studied toward synthesis of biscoumarin materials by a domino knoevenagel–michael reaction of 4-hydroxycoumarin with aromatic and heterocyclic aldehydes under solvent-free conditions (70 °c) within 15–30 min. the applied nanocomposite system was easily and magnetically separated from the reaction mixture and reused for six consecutive cycles without the significant loss of its catalytic activity.