CuI-functionalized halloysite nanoclay as an efficient heterogeneous catalyst for promoting click reactions: Combination of experimental and computational chemistry

Amine-functionalized halloysite nanotubes (HNTs-2N) were prepared and further modified by introduction of salicylaldehyde and formation of imine functionality (HNTs-2N-Sal). The latter was subsequently used for immobilization of CuI and formation of CuI@HNTs-2N-Sal, which could effectively promote click reactions of terminal alkynes, sodium azide and -haloketones or alkyl halides in aqueous media and under mild reaction conditions to afford 1,2,3-triazoles in relatively short reaction times. Notably, the catalyst could be recycled in up to six reaction runs with negligible loss of catalytic activity and CuI leaching. Also, the geometry of CuI adsorption on the modified HNTs surface was explored by molecular simulation with density functional theory. Furthermore, topographic steric maps of possible coordination modes were obtained using the recently released SambVca2 web application tool. Based on obtained results, a catalytic site with superior performance was suggested.