Synthesis of a bistriazolyl-phenanthroline–Cu(II) complex immobilized on nanomagnetic iron oxide as a novel green catalyst for synthesis of imidazoles via annulation reactions† R

We designed and prepared a novel N-heterocycle-based nanocatalyst by a post synthetic method, namely
the [Fe3O4@DAA-BTrzPhen–Cu(II)] composite. In this method, bistriazolyl-phenanthroline groups were
stepwise synthesized on an Fe3O4 substrate and used as a tetradentate nitrogenous ligand for
coordinating to copper ions. The obtained nanocomposite was well characterized using FT-IR, PXRD,
TGA, EDAX, ICP-OES, EDX-mapping, SEM, TEM, VSM and BET analyses, which confirm the formation of
a thermostable crystalline spherical particle morphology with the particle size in the range of 17 nm to
25 nm and a magnetization value of 42 emu g−1
. Also, the catalytic activity of [Fe3O4@DAA-BTrzPhen–
Cu(II)] as a novel and magnetically separable heterogeneous nanocatalyst was evaluated in preparing
various tetrasubstituted imidazole derivatives from one-pot four-component condensation of anilines,
aldehydes, 1,2-diketones and ammonium acetate, and favorable products were produced with excellent
yields. The stability, low Cu leaching, and heterogenous nature of the nanocatalyst were confirmed by
hot-filtration and leaching tests. The copper based nanocatalyst could be easily recovered by magnetic
field separation and recycled at least 8 times in a row without noticeable loss in its catalytic activit