Small Organic Molecule‐Assisted Mesoscopic Self‐Assembly of SnO 2 Nanoparticles: An Efficient Catalyst for the Synthesis of β‐Nitroaldol

Over the past few decades, huge number of mesoporous materials have been synthesized by using supramolecular assembly of ionic/non‐ionic surfactants as structure‐directing agents (SDAs). Here, we report a facile synthetic strategy to fabricate self‐assembled SnO 2 nanoparticles with well‐defined nanocrystalline spherical morphology and mesoporosity using sodium salicylate as a SDA and stabilizing agent. The mesophases of the materials were investigated by powder X‐ray diffraction, TEM and N 2 sorption studies. TEM results show that the mesopores are formed by the assembly of ultrasmall SnO 2 NPs with broad range of interparticle voids and N 2 sorption studies agreed well with this TEM data. This synthesis strategy facilitated the generation of SnO 2 NPs with increased surface area and pores of nanoscale dimensions with a large number of exposed surface‐active sites. The photoinduced electron transfer in these materials was investigated by the fluorescence quenching study with pyranine, which suggested the presence of surface Lewis basicity. The materials showed excellent catalytic activity for the synthesis of β‐nitroaldol through the reaction of benzaldehyde and nitromethane. The heterogeneous nature of the catalyst could be attributed to the high surface area, presence of numerous surface active sites, and structural robustness of the self‐assembled SnO 2 nanostructure. The catalysts exhibited negligible loss in activity after several catalytic cycles.