Surfactant-assisted synthesis of a novel macroporous tin organophosphonate with mesoporous walls

A novel hierarchically mesoporous–macroporous tin organophosphonate with intra-framework organic groups is successfully fabricated through a facile hydrothermal route with SnCl₄·5H₂O as tin source and diethylene triamine pentakis(methylphosphonic acid) as organophosphorus source in the presence of cetyltrimethylammonium bromide (CTAB) as the templating agent. The as-prepared hybrid had macroporous structures with the pore size in the range of 0.6–2.1 μm and a specific surface area of 170 m²/g. Besides, the pore walls had particle-aggregated mesoporous substructures, consisting of amorphous tin organophosphonates, as characterized by SEM, TEM and N₂ adsorption analysis and wide- and low-angle X-ray diffraction. FT-IR and NMR results indicated the integrity of the organophosphonate groups into the hybrid solid. It was found that the surfactant CTAB played an important role in obtaining macropores, and a possible formation route was proposed.