Copper(I) Oxide Nanoparticles Supported on Magnetic Casein as a Bio-Supported and Magnetically Recoverable Catalyst for Aqueous Click Chemistry Synthesis of 1,4-Disbustituted 1,2,3-Triazoles

As is well known, nanoparticles with small sizes tend to aggregate in solution. To avoid uncontrolled growth or aggregation in the preparation of nanoparticles, the stabilizer such as polymers, surfactants or small organic molecules is often used[1]. Casein, a proline rich globular protein which is readily available in milk, can be thought as block copolymers consisting of blocks with high levels of hydrophobic or hydrophilic amino acid residues[2]. As a part of our ongoing research program on the development of new catalytic systems with emphasise on green and natural supports[3], herein, we present a successful preparation and excellent catalytic activity of copper(I) oxide nanoparticles supported on magnetic casein (Cu2O/Casein@Fe3O4NPs). One-Pot three-component reaction of various alkyl halides, sodium azide and various alkynes was carried out under environmentally-friendly conditions with excellent yields in short reaction time at room temperature (Figure 1). To the best of our knowledge, this work is presented as the first example to demonstrate the usefulness of casein as a support for copper(I) oxide nanoparticles and it is a novel catalyst with unique properties for the Huisgen 1,3-dipolar cycloaddition to prepare 1,4-disubstituted-1,2,3-triazoles.