ScholarWorks@UNO

Studies directed toward the development of transition metal@halloysite nanocomposite materials for organic transformations

A reliable method for the encapsulation of copper nanoparticles (2-4 nm) in halloysite nanoscrolls (Cu@Hal) has been developed. The nanocomposite was prepared using a green wet chemical synthetic method which involved reduction of Cu(NO3)2•3H2O with NaBH4 in the presence of trisodium citrate and halloysite. The new Cu@Hal nanocomposite was employed in the azide-alkyne Huisgen "Click" cycloaddition reaction to afford 1,2,3-triazoles. The Cu@Hal nanocomposite was found to be a highly efficient room temperature catalyst for the synthesis of a diverse array of triazoles in water within 1-2 hours. Cu@Hal was used in catalytic amounts and demonstrated high selectivity for the 1,4 disubstituted triazole isomer with the absence of byproducts. The Cu@Hal catalyst has remarkable stability in water and air and can be easily recovered. Details of the synthesis of the nanocomposite Cu@Hal and the scope of the Cu@Hal catalyzed azide-alkyne Huisgen "Click" cycloaddition reaction will be presented.