Abstract
Heterogeneous and versatile NiO–SiO
2
NCs were synthesized by a sol–gel technique and used as a catalyst for the one-pot multicomponent synthesis of benzodiazepine derivatives (
4a–u
) from a mixture of
o
-phenylenediamine, aromatic aldehydes and dimedone under microwave irradiation. Tetraethyl orthosilicate (TEOS) was used as a source of SiO
2
for the creation of the NiO–SiO
2
NCs. This catalytic protocol has many advantages, such as simple work up, inexpensive precursors, short reaction time, high yield and high surface area. The structure and morphology of the prepared nanocatalyst was characterized by using elemental analysis, scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), energy-dispersive X-ray spectroscopy (EDAX) and Fourier transform infrared (FTIR) spectroscopy.
1
H NMR,
13
C NMR and MS analyses were performed to confirm the synthesized compounds (
4a–u
). Moreover, the remarkable catalytic properties of the NiO–SiO
2
NCs permit easy separation of the catalyst from the reaction mixture without significant loss of catalytic activity.