SnTUD-1: a solid acid catalyst for three component coupling reactions at room temperature

Abstract

A novel wormhole structured mesoporous material containing tin, SnTUD-1, was prepared by a direct hydrothermal synthesis method using triethanolamine (TEA) as an organic inexpensive mesoporous structure directing agent. XRD and N₂ sorption studies of SnTUD-1 confirmed the amorphous mesoporous nature of SnTUD-1, which possessed a large surface area of 555 m² g⁻¹ and a pore diameter of 7.4 nm. HR-TEM further ascertained the disordered pores in their morphology and the presence of nano-domains of SnO₂ species. The nature of the Sn⁴⁺ ion co-ordination with the silica matrix was evaluated by using different techniques including diffuse reflectance UV-Vis, FTIR, ²⁹Si MAS NMR and XPS. SnTUD-1 had an interesting Lewis acidity as measured by FTIR of pyridine adsorption which provided excellent activities in one-pot three-component Mannich-type reactions of ketones with aldehydes and amines at room temperature.