Perfluoralkyl/Rose Bengal Functionalized Janus Silica Nanoparticles for Photocatalytic Transformations with Singlet Oxygen

A Janus mesoporous silica material with an imidazolium-based ionic liquid and perflouroalkyl motifs was synthesized using hollow Stober particles. Its morphology, chemical composition and surface properties were characterized by N2 physisorption analysis, scanning and transmission electron microscopy, elemental mapping, thermogravimetric and elemental analysis, and solid state NMR spectroscopy. The Janus nanoparticles have independent faces with fluorophilic and hydrophilic properties suitable for interaction with oxygen and Rose Bengal, which is a known photosensitizer for singlet oxygen generation. The catalytic activity of these Janus particles was evaluated in a series of transformations using singlet oxygen. They provide the desired products in high yield and selectivity. Anisotropic Janus nanosheets containing electrostatically grafted Rose Bengal and highly hydrophobic fluorinated octyl groups on opposite sides were fabricated from crushed Janus hollow spheres. The material showed excellent activity in various photochemical transformations under green LED irradiation.image