Generalized 'one-pot' preparative strategy to obtain highly functionalized silica-based mesoporous spherical particles

In this work we present a synthesis strategy for the preparation of Stöber-type mesoporous particles functionalized with inorganic species. The procedure is based on a combination of the Atrane and the Stöber methods. Both as a source of silicon and of the incorporated heteroelements (Fe, Zn, Al, Ti) the corresponding atrane complexes are used as hydrolytic reagents. These complexes are easily formed by reaction with triethanolamine. Mesoporosity is achieved using surfactant micelles as templates. Obtaining uniform spherical particles is achieved by optimizing the amount of water-ethanol in the reaction medium. The particle sizes have been modulated by controlling simple parameters such as reaction time or temperature. The incorporation of inorganic species is on many occasions incompatible with the preservation of spherical morphology, resulting in heterogeneous particles in shape and size and even phase segregation for high functionalization degrees. The methodology that we propose makes it possible to achieve a high concentration of highly dispersed heteroelements (even at molecular level), maintaining, to a large extent, both sphericity and particle size homogeneity. The Si/M molar ratios achieved are significantly lower (greater functionalization) than those usually reported in the literature. The strategy is generalizable for the incorporation of a great variety of elements, and specially for first row transition elements.