Investigating the effect of immobilization of yttrium-Schiff base onto magnetite nanoparticles: enhanced catalytic activity in the synthesis of dihydropyrimidinones under solvent-free conditions

摘要

A new complex of yttrium-salpr was synthesized through the reaction of Y(NO3)(3)center dot 6(H2O) and salpr Schiff base (salpr = N,N'-bis(3-salicylidenaminopropyl) amine). The prepared complex was characterized by Mid and Far-IR, C-13-NMR, H-1-NMR, UV-Vis, XRF, and CHN. The obtained data suggested a binuclear structure for this compound. To our surprise, the catalytic activity of this complex was even lower than its precursor, Y(NO3)(3)center dot 6(H2O), in one-pot synthesis of dihydropyrimidinones under solvent-free conditions. As one of the reasons of this reduced activity should pertain to the binuclear structure of the complex that reduces the availability of yttrium in the reaction, the complex was immobilized on modified Fe3O4 nanoparticles, which not only increases the surface to the volume ratio of the compound, but also hinders the formation of binuclear structure due to site (Schiff base) isolation. These prepared nanoparticles depicted noticeably high catalytic activity as well as good recyclability and very easy separation.