preparation, characterization and application of a novel organic-inorganic hybrid magnetic nanomaterial as a highly efficient catalyst for the synthesis of bis-coumarins

a novel organic-inorganic hybrid magnetic nanomaterial, namely nano-[fe3o4@sio2@r-nme2][fecl4] (nano-[fsrn][fecl4]) was prepared, and characterized by edx, elemental mapping, fe-sem, ft-ir, xrd, vsm, tg and dtg analyses. then, it was applied as a highly efficient and magnetically recyclable catalyst for the solvent-free synthesis of bis-coumarins from 4-hydroxycoumarin (2 eq.) and arylaldehydes (1 eq.). nme2 is a basic group, and fecl4− is a lewis acid; thus, nano-[fsrn][fecl4] can act as a dual-functional catalyst; based on this and the literature, a plausible mechanism was proposed for the reaction.