Fabrication of palladium nanoparticle decorated silica nanotubes for olefination of aryl iodides

Abstract

Preparation of anisotropic material with various functionality has been widely studied and the applications of these fascinating materials in micro/nano size have advantages distinguished from traditional bulk materials. The anisotropic nano material having different in-and-out functional groups can be utilized as selective nanocarrier and smart nanocatalyst. In this paper, silica nanotube was fabricated by vapor phase synthesis (VPS) method using anodic aluminum oxide (AAO) as hard template for olefination of aryl iodide and carboxylic group was introduced inside the silica nanotube by vapor deposition polymerization (VDP) method. Then, silica nanotube with in-and-out bifunctionality was successfully fabricated by additional hydrophobic silane treatment. Furthermore, palladium nanoparticle can be introduced to silica nanotube with different in-and-out bifunctional group selectively. Then, palladium ion was inserted inside of the nanotube and the palladium ion was reduced by hydrogen gas. The palladium ion can be coordinated with the carboxyl group of bifunctional silica nanotube. Heck reaction for 3 types of olefination of aryl iodides was conducted by Pd-inserted bifunctional silica nanotube and the highest olefination efficiency of 99% was obtained. Our novel approach may open up a new method for fabrication of an anisotropic carrier for nano-catalytic application.