MoO3-ZrO2 Nanocomposite Oxide: A Green Heterogeneous Catalyst Towards Environmentally Benign Synthesis of Some Bbiologically Potent Molecules

Abstract

A Series of MoO3-ZrO2nanocomposite oxide was synthesized by different methods like co-precipitation, impregnation methods and combustion synthesis method. The synthesized nanomaterials were characterized by X-ray diffraction (XRD), Scanning electron microscopy (SEM), Transmission electron microscopy (TEM) and UV-Vis spectroscopic technique. XRD study revealed selective stabilization of the tetragonal phase of zirconia in presence of MoO3. The crystallite size calculated from the Fourier line shape analysis of the broadened X-ray diffraction profiles were in line with TEM observations. Oxide nanoparticles with size in the range of 5-30 nm were observed depending upon preparation method. UV-Vis study revealed well dispersion of the molybdenum oxide component in the zirconia matrix in the form of isolated and cluster molybdates. The MoO3(20 mol%)-ZrO2nanocomposite oxide synthesized by precipitation method was exploited as an efficient heterogeneous catalyst for synthesis of biologically important molecules like amidoalkylnaphthols and β-acetamido ketones under solvent free conditions using conventional as well as microwave heating. The results obtained clearly showed that nanocomposite oxide catalyst was recyclable and highly efficient for the reaction giving good yield and purity of the products. Similarly, the MoO3-ZrO2nanocomposite oxide prepared by combustion method was explored as an efficient and environmentally benign catalyst for the synthesis of octahydroqunazolinones by multicomponent condensation reaction of dimedone, urea and arylaldehydes in aqueous media as well as under solvent free condition using microwave irradiation. The MoO3 (10 mol%)-ZrO2 catalyst was found to be highly active for the transformation with excellent yield and purity of the product in a short reaction time. The protocols developed using the MoO3-ZrO2nanocomposite oxide were found to be advantageous in terms of simple experimentation, preclusion of toxic solvents, green reaction media and high yield and purity of product.